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Genome-wide sequencing of multiple sectors in glioblastoma
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Diagnostic workflows for glioblastoma (GBM) patients increasingly include DNA sequencing-based analysis of a single tumor site following biopsy or resection. We hypothesized that sequencing of multiple sectors within a given tumor would provide a more comprehensive representation of the molecular landscape and potentially inform therapeutic strategies.
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"The Cancer Genome Atlas (TCGA) has used the latest sequencing and analysis methods to identify somatic variants across thousands of tumours. Here we present data and analytical results for point mutations and small insertions/deletions from 3,281 tumours across 12 tumour types as part of the TCGA Pan-Cancer effort. We illustrate the distributions of mutation frequencies, types and contexts across tumour types, and establish their links to tissues of origin, environmental/carcinogen influences, and DNA repair defects. Using the integrated data sets, we identified 127 significantly mutated genes from well-known (for example, mitogen-activated protein kinase, phosphatidylinositol-3-OH kinase, Wnt/β-catenin and receptor tyrosine kinase signalling pathways, and cell cycle control) and emerging (for example, histone, histone modification, splicing, metabolism and proteolysis) cellular processes in cancer. The average number of mutations in these significantly mutated genes varies across tumour types; most tumours have two to six, indicating that the number of driver mutations required during oncogenesis is relatively small. Mutations in transcriptional factors/regulators show tissue specificity, whereas histone modifiers are often mutated across several cancer types. Clinical association analysis identifies genes having a significant effect on survival, and investigations of mutations with respect to clonal/subclonal architecture delineate their temporal orders during tumorigenesis. Taken together, these results lay the groundwork for developing new diagnostics and individualizing cancer treatment.",
"The World Health Organization (WHO) classification and grading system attempts to predict the clinical course of meningiomas based on morphological parameters. However, because of high interobserver variation of some criteria, more reliable prognostic markers are required. Here, we assessed the TERT promoter for mutations in the hotspot regions C228T and C250T in meningioma samples from 252 patients. Mutations were detected in 16 samples (6.4% across the cohort, 1.7%, 5.7%, and 20.0% of WHO grade I, II, and III cases, respectively). Data were analyzed by t test, Fisher's exact test, log-rank test, and Cox proportional hazard model. All statistical tests were two-sided. Within a mean follow-up time in surviving patients of 68.1 months, TERT promoter mutations were statistically significantly associated with shorter time to progression (P < .001). Median time to progression among mutant cases was 10.1 months compared with 179.0 months among wild-type cases. Our results indicate that the inclusion of molecular data (ie, analysis of TERT promoter status) into a histologically and genetically integrated classification and grading system for meningiomas increases prognostic power. Consequently, we propose to incorporate the assessment of TERT promoter status in upcoming grading schemes for meningioma.",
"TERT promoter gene mutations are highly recurrent in malignant glioma. However, little information exists regarding their presence in experimental brain tumor models. To better characterize systems in which TERT mutation studies could be appropriately modeled experimentally, the TERT promoter was examined by conventional sequencing in primary brain tumor initiating cells (BTIC), two matched recurrent BTIC lines, a panel of established malignant glioma cell lines, and two meningioma cell lines. Telomerase gene expression was examined by quantitative PCR. We found that all glioblastoma BTIC lines harbored a TERT mutation, which was retained in two patient-matched recurrent BTIC. The TERT C228T or C250T mutation was found in 33/35 (94 %) of established malignant glioma cell lines and both meningioma cell lines examined. Brain tumor cell lines expressed variably high telomerase levels. Thus, a high percentage of glioma cell lines, as well as two meningioma cell lines, harbors TERT mutations. These data characterize tractable, accessible models with which to further explore telomerase biology in these tumor types.",
"To understand the relationships between the non-GCIMP glioblastoma (GBM) subgroups, we performed mathematical modeling to predict the temporal sequence of driver events during tumorigenesis. The most common order of evolutionary events is 1) chromosome (chr) 7 gain and chr10 loss, followed by 2) CDKN2A loss and/or TP53 mutation, and 3) alterations canonical for specific subtypes. We then developed a computational methodology to identify drivers of broad copy number changes, identifying PDGFA (chr7) and PTEN (chr10) as driving initial nondisjunction events. These predictions were validated using mouse modeling, showing that PDGFA is sufficient to induce proneural-like gliomas and that additional NF1 loss converts proneural to the mesenchymal subtype. Our findings suggest that most non-GCIMP mesenchymal GBMs arise as, and evolve from, a proneural-like precursor.",
"Here we report that promoter mutations in telomerase (TERT), the most common noncoding mutations in cancer, give rise to monoallelic expression of TERT. Through deep RNA sequencing, we find that TERT activation in human cancer cell lines can occur in either mono- or biallelic manner. Without exception, hotspot TERT promoter mutations lead to the re-expression of only one allele, accounting for approximately half of the observed cases of monoallelic TERT expression. Furthermore, we show that monoallelic TERT expression is highly prevalent in certain tumor types and widespread across a broad spectrum of cancers. Taken together, these observations provide insights into the mechanisms of TERT activation and the ramifications of noncoding mutations in cancer.",
"Glioblastoma (GBM) is a prototypical heterogeneous brain tumor refractory to conventional therapy. A small residual population of cells escapes surgery and chemoradiation, resulting in a typically fatal tumor recurrence ∼ 7 mo after diagnosis. Understanding the molecular architecture of this residual population is critical for the development of successful therapies. We used whole-genome sequencing and whole-exome sequencing of multiple sectors from primary and paired recurrent GBM tumors to reconstruct the genomic profile of residual, therapy resistant tumor initiating cells. We found that genetic alteration of the p53 pathway is a primary molecular event predictive of a high number of subclonal mutations in glioblastoma. The genomic road leading to recurrence is highly idiosyncratic but can be broadly classified into linear recurrences that share extensive genetic similarity with the primary tumor and can be directly traced to one of its specific sectors, and divergent recurrences that share few genetic alterations with the primary tumor and originate from cells that branched off early during tumorigenesis. Our study provides mechanistic insights into how genetic alterations in primary tumors impact the ensuing evolution of tumor cells and the emergence of subclonal heterogeneity."
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what is activating transcription factor 3
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Activating transcription factor 3 (ATF3) is a member of the ATF/cAMP-response element binding protein (CREB) family of transcription factors. In response to stress stimuli, ATF3 forms dimers to activate or repress gene expression. Further, ATF3 modulates the immune response, atherogenesis, cell cycle, apoptosis, and glucose homeostasis. Recent studies have shown that ATF3 may also be involved in pathogenesis of other diseases. However, more studies are needed to determine the role of ATF3 in metabolic regulation.
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"We isolated a gene from a mouse pituitary cDNA library that encodes a protein highly homologous to nuclear factor CREB, an activator of cAMP-responsive promoter elements (CREs). We demonstrate that while CREB is expressed uniformly in several cell types, this gene, termed CREM, shows cell-specific expression. CREM has a remarkable organization, since down-stream of the stop codon there is a second, out-of-frame DNA-binding domain. Using PCR and RNAase protection analysis, we have identified three mRNA isoforms that appear to be obtained by differential cell-specific splicing. Sequencing of the isoforms demonstrated alternative usage of the two DNA-binding domains. CREM proteins reveal the same efficiency and specificity of binding to CRE sequences as CREB, but in contrast to CREB, CREM acts as a down-regulator of cAMP-induced transcription.",
"Obesity and type 2 diabetes (T2D) trigger a harmful stress-induced cardiac remodeling process known as cardiomyopathy. These diseases represent a serious and widespread health problem in the Western world; however the underlying molecular basis is not clear. ATF3 is an 'immediate early' gene whose expression is highly and transiently induced in response to multiple stressors such as metabolic, oxidative, endoplasmic reticulum and inflammation, stressors that are involved in T2D cardiomyopathy. The role of ATF3 in diabetic cardiomyopathy is currently unknown. Our research has aimed to study the effect of ATF3 expression on cardiomyocytes, heart function and glucose homeostasis in an obesity-induced T2D mouse model. We used wild type mice (WT) as well as mutant mice with a cardiac-specific ATF3 deficiency (ATF3-cKO). Mice were fed a high-fat diet (HFD) for 15 weeks. HFD induced high ATF3 expression in cardiomyocytes. Mice were examined for cardiac remodeling processes and the diabetic state was assessed. HFD-fed ATF3-cKO mice exhibited severe cardiac fibrosis, higher levels of heart hypertrophic markers, increased inflammation and worse cardiac function, as compared to WT mice. Interestingly, HFD-fed ATF3-cKO mice display increased hyperglycemia and reduced glucose tolerance, despite higher blood insulin levels, as compared to HFD-fed WT mice. Elevated levels of the cardiac inflammatory cytokines IL-6 and TNFα leading to impaired insulin signalling may partially explain the peripheral glucose intolerance. Cardiac ATF3 has a protective role in dampening the HFD-induced cardiac remodeling processes. ATF3 exerts both local and systemic effects related to T2D-induced cardiomyopathy. This study provides a strong relationship between heart remodeling processes and blood glucose homeostasis.",
"The purpose of this review is to discuss ATF3, a member of the ATF/CREB family of transcription factors, and its roles in stress responses. In the introduction, we briefly describe the ATF/CREB family, which contains more than 10 proteins with the basic region-leucine zipper (bZip) DNA binding domain. We summarize their DNA binding and heterodimer formation with other bZip proteins, and discuss the nomenclature of these proteins. Over the years, identical or homologous cDNA clones have been isolated by different laboratories and given different names. We group these proteins into subgroups according to their amino acid similarity; we also list the alternative names for each member, and clarify some potential confusion in the nomenclature of this family of proteins. We then focus on ATF3 and its potential roles in stress responses. We review the evidence that the mRNA level of ATF3 greatly increases when the cells are exposed to stress signals. In animal experiments, the signals include ischemia, ischemia coupled with reperfusion, wounding, axotomy, toxicity, and seizure; in cultured cells, the signals include serum factors, cytokines, genotoxic agents, cell death-inducing agents, and the adenoviral protein E1A. Despite the overwhelming evidence for its induction by stress signals, not much else is known about ATF3. Preliminary results suggest that the JNK/SAPK pathway is involved in the induction of ATF3 by stress signals; in addition, IL-6 and p53 have been demonstrated to be required for the induction of ATF3 under certain conditions. The consequences of inducing ATF3 during stress responses are not clear. Transient transfection and in vitro transcription assays indicate that ATF3 represses transcription as a homodimer; however, ATF3 can activate transcription when coexpressed with its heterodimeric partners or other proteins. Therefore, it is possible that, when induced during stress responses, ATF3 activates some target genes but represses others, depending on the promoter context and cellular context. Even less is understood about the physiological significance of inducing ATF3. We will discuss our preliminary results and some reports by other investigators in this regard.",
"Activating transcription factor 3 (ATF3) is a member of the ATF/cyclic AMP response element-binding (ATF/CREB) family of transcription factors. It is an adaptive-response gene that participates in cellular processes to adapt to extra- and/or intracellular changes, where it transduces signals from various receptors to activate or repress gene expression. Advances made in understanding the immunobiology of Toll-like receptors have recently generated new momentum for the study of ATF3 in immunity. Moreover, the role of ATF3 in the regulation of the cell cycle and apoptosis has important implications for understanding susceptibility to and progression of several cancers.",
"Cyclic AMP (cAMP) is an intracellular second messenger that activates transcription of many cellular genes. A palindromic consensus DNA sequence, TGACGTCA, functions as a cAMP-responsive transcriptional enhancer (CRE). The CRE binds a cellular protein of 38 kD in placental JEG-3 cells. A placental lambda gt11 library was screened for expression of specific CRE-binding proteins with the CRE sequence as a radioactive probe. A cDNA encoding a protein of 326 amino acids with the binding properties of a specific CRE-binding protein (CREB) was isolated. The protein contains a COOH-terminal basic region adjacent to a sequence similar to the \"leucine zipper\" sequence believed to be involved in DNA binding and in protein-protein contacts in several other DNA-associated transcriptional proteins including the products of the c-myc, c-fos, and c-jun oncogenes and GCN4. The CREB protein also contains an NH2-terminal acidic region proposed to be a potential transcriptional activation domain. The putative DNA-binding domain of CREB is structurally similar to the corresponding domains in the phorbol ester-responsive c-jun protein and the yeast transcription factor GCN4.",
"In obese Zucker diabetic fatty (ZDF) rats, ER stress is associated with insulin resistance and pancreatic β-cell dysfunction; however the exact mechanisms by which ER stress drives type-2 diabetes remain uncertain. Here, we investigated the role of ATF3 on the preventive regulation of AMPK against ER stress-mediated β-cell dysfunction during the end-stage progression of hyperglycemia in ZDF rats. The impaired glucose metabolism and β-cell dysfunction were significantly increased in late-diabetic phase 19-week-old ZDF rats. Although AMPK phosphorylation reduced in 6- and 12-week-old ZDF rats was remarkably increased at 19weeks, the increases of lipogenice genes, ATF3, and ER stress or ROS-mediated β-cell dysfunction were still remained, which were attenuated by in vivo-injection of chemical chaperon tauroursodeoxycholate (TUDCA), chronic AICAR, or antioxidants. ATF3 did not directly affect AMPK phosphorylation, but counteracts the preventive effects of AMPK for high glucose-induced β-cell dysfunction. Moreover, knockdown of ATF3 by delivery of in vivo-jetPEI ATF3 siRNA attenuated ER stress-mediated β-cell dysfunction and enhanced the beneficial effect of AICAR. Our data suggest that ATF3 may play as a counteracting regulator of AMPK and thus promote β-cell dysfunction and the development of type-2 diabetes and could be a potential therapeutic target in treating type-2 diabetes.",
"An activating transcription factor (ATF)-binding site (consensus sequence 5'-GTGACGTACAG-3') is a promoter element present in a wide variety of viral and cellular genes. The two best-characterized classes of genes that contain ATF sites are E1A-inducible adenoviral genes and cAMP-inducible cellular genes. Here, we report the isolation of eight ATF cDNA clones, each of which is derived from a separate gene. All ATF cDNA clones examined contain a leucine zipper motif and are significantly similar to one another only within this region. The leucine zipper region of ATF proteins is also similar to that of the AP-1/c-jun family of transcription factors, whose DNA-binding site differs from the ATF-binding site at a single position. DNA binding studies reveal two mechanisms for generating further diversity from the ATF proteins. First, some, but not all, combinations of ATF proteins form heterodimers that efficiently bind to DNA. Second, although all ATF proteins bind to the ATF site, their precise interactions with DNA differ from one another, as evidenced by methylation interference analysis. Our results help to explain how a single promoter element, an ATF site, can be present in a wide variety of promoters."
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Genetics of Colorectal Cancer in African Americans
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African Americans have a higher incidence and mortality from colorectal cancer. This disparity might be due, in part, to the type of mutations in driver genes. In this study, we examined alterations specific to
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"Hereditary and sporadic gastrointestinal cancer of the microsatellite mutator phenotype (MMP) is characterized by a remarkable genomic instability at simple repeated sequences. The genomic instability is often caused by germline and somatic mutations in DNA mismatch repair (MMR) genes hMSH2 and hMLH1. The MMP can be also caused by epigenetic inactivation of hMLH1. The MMP generates many somatic frameshift mutations in genes containing mononucleotide repeats. We previously reported that in MMP tumors the hMSH6 and hMSH3 MMR genes often carry frameshift mutations in their (C)(8) and (A)(8) tracks, respectively. We proposed that these 'secondary mutator mutations' contribute to a gradual manifestation of the MMP. Here we report the detection of other frameshift, nonsense, and missense mutations in these genes in colon and gastric cancers of the MMP. A germline frameshift mutation was found in hMSH6 in a colon tumor harboring another somatic frameshift mutation. Several germline sequence variants and somatic missense mutations at conserved residues were detected in hMSH6 and only one was detected in hMSH3. Of the three hMSH6 germline variants in conserved residues, one coexisted with a somatic mutation at the (C)(8) track and another had a somatic missense mutation. We suggest that some of these germline and somatic missense variants are pathogenic. While biallelic hMSH6 and hMSH3 frameshift mutations were found in some tumors, many tumors seemed to contain only monoallelic mutations. In some tumors, these somatic monoallelic frameshift mutations at the (C)(8) and (A)(8) tracks were found to coexist with other somatic mutations in the other allele, supporting their functionality during tumorigenesis. However, the low incidence of these additional somatic mutations in hMSH6 and hMSH3 leaves many tumors with only monoallelic mutations. The impact of the frameshift mutations in gene expression was studied by comparative analysis of RNA and protein expression in different tumor cell clones with different genotypes. The results show that the hMSH6 (C)(8) frameshift mutation abolishes protein expression, ruling out a dominant negative effect by a truncated protein. We suggest the functionality of these secondary monoallelic mutator mutations in the context of an accumulative haploinsufficiency model.",
"To characterize somatic alterations in colorectal carcinoma, we conducted a genome-scale analysis of 276 samples, analysing exome sequence, DNA copy number, promoter methylation and messenger RNA and microRNA expression. A subset of these samples (97) underwent low-depth-of-coverage whole-genome sequencing. In total, 16% of colorectal carcinomas were found to be hypermutated: three-quarters of these had the expected high microsatellite instability, usually with hypermethylation and MLH1 silencing, and one-quarter had somatic mismatch-repair gene and polymerase ε (POLE) mutations. Excluding the hypermutated cancers, colon and rectum cancers were found to have considerably similar patterns of genomic alteration. Twenty-four genes were significantly mutated, and in addition to the expected APC, TP53, SMAD4, PIK3CA and KRAS mutations, we found frequent mutations in ARID1A, SOX9 and FAM123B. Recurrent copy-number alterations include potentially drug-targetable amplifications of ERBB2 and newly discovered amplification of IGF2. Recurrent chromosomal translocations include the fusion of NAV2 and WNT pathway member TCF7L1. Integrative analyses suggest new markers for aggressive colorectal carcinoma and an important role for MYC-directed transcriptional activation and repression.",
"Phase I and II clinical trails are currently investigating the antitumor activity of cisplatin and camptothecins (CPTs; DNA topoisomerase I poisons), based on the dramatic synergistic cytotoxicity of these agents in some preclinical models. However, the mechanistic basis for this synergism is poorly understood. By exploiting the evolutionary conservation of DNA repair pathways from genetically tractable organisms such as budding and fission yeasts to mammalian cells, we demonstrate that the synergism of CPT and cisplatin requires homologous recombination. In yeast and mammalian cell lines defective for RAD52 and XRCC2/3, respectively, the combination of these agents proved antagonistic, while greater than additive activity was evident in isogenic wild-type cells. Homologous recombination appears to mediate a similar interaction of X-rays and CPT, but antagonizes the synergism of cytarabine (Ara-C) with CPT. These findings suggest that homologous recombination comprises an evolutionarily conserved determinant of cellular sensitivity when CPTs are used in combination with other therapeutics.",
"The loss of DNA mismatch repair (MMR) is responsible for hereditary nonpolyposis colorectal cancer and a subset of sporadic tumors. Acquired resistance or tolerance to some anti-cancer drugs occurs when MMR function is impaired. 5-Fluorouracil (FU), an anti-cancer drug used in the treatment of advanced colorectal and other cancers, and its metabolites are incorporated into RNA and DNA and inhibit thymidylate synthase resulting in depletion of dTTP and incorporation in DNA of uracil. Although the MMR deficiency has been implicated in tolerance to FU, the mechanism of cell killing remains unclear. Here, we examine the cellular response to fluorodeoxyuridine (FdU) and the role of the MMR system. After brief exposure of cells to low doses of FdU, MMR mediates DNA damage signaling during S-phase and triggers arrest in G2/M in the first cell cycle in a manner requiring MutSalpha, MutLalpha, and DNA replication. Cell cycle arrest is mediated by ATR kinase and results in phosphorylation of Chk1 and SMC1. MutSalpha binds FdU:G mispairs in vitro consistent with its being a DNA damage sensor. Prolonged treatment with FdU results in an irreversible arrest in G2 that is independent of MMR status and leads to the accumulation of DNA lesions that are targeted by the base excision repair (BER) pathway. Thus, MMR can act as a direct sensor of FdU-mediated DNA lesions eliciting cell cycle arrest via the ATR/Chk1 pathway. However, at higher levels of damage, other damage surveillance pathways such as BER also play important roles.",
"Inactivation of the adenomatous polyposis coli (APC) gene is a major initiating event in colorectal tumorigenesis. Most of the mutations in APC generate premature stop codons leading to truncated proteins that have lost beta-catenin binding sites. APC-free beta-catenin stimulates the Wnt signaling pathway, leading to active transcription of target genes. In the current study, we describe a novel mechanism for APC regulation. We show that miR-135a&b target the 3' untranslated region of APC, suppress its expression, and induce downstream Wnt pathway activity. Interestingly, we find a considerable up-regulation of miR-135a&b in colorectal adenomas and carcinomas, which significantly correlated with low APC mRNA levels. This genetic interaction is also preserved in full-blown cancer cell lines expressing miR-135a&b, regardless of the mutational status of APC. Thus, our results uncover a miRNA-mediated mechanism for the control of APC expression and Wnt pathway activity, and suggest its contribution to colorectal cancer pathogenesis.",
"Colorectal cancers are the third most common in both sexes and they are the second most common cause of cancer-related death. 12-15% of colorectal cancers develop through microsatellite instability (the hereditary mutation in at least one of DNA mismatch repair genes) pathway and they are 2-5% hereditary. In this study, we investigated the correlation between the clinicopathological features themselves and also the correlation between them and the immunohistochemical MLH-1, MSH-2, PMS-2, MSH-6 expressions in a total of 186 resection materials with colorectal adenocarcinoma between 2008 and 2012. All the cases were retrospectively evaluated in terms of age, sex, localization, size, accompanying polyp, multiple tumor, arising from polyp, differentiation, mucinous differentiation, pathological tumor stage, lymphovascular and perineural invasion, lymphocyte amount in the tumor microenvironment, surgical border and lymph node metastasis. We prepared multiple tissue blocks which had 4-millimeter tumor. Immunohistochemically, MLH-1, MSH-2, PMS-2, MSH-6 primary antibodies were studied. Statistically, \"Kruskal-Wallis\" ve \"Pearson's chi-squared\" tests were used. We found a positive correlation between loss of MLH-1 and PMS-2 expressions and the right-colon location, poor and mucinous differentiation and dense lymphocytic infiltration. In addition, loss of MSH-2 and MSH-6 expressions was correlated with the right-colon location, poor and mucinous differentiation. We found a meaningful relationship between immunohistochemical markers and clinicopathological features usually observed in tumors with microsatellite instability. This finding may arouse suspicion for MSI. However, the findings in our study must be supported with studies conducted in large series including molecular methods.",
"Repair of mismatches in DNA in mammalian cells is mediated by a complex of proteins that are members of two highly conserved families of genes referred to as MutS and MutL homologues. Germline mutations in several members of these families, MSH2, MSH6, MLH1, and PMS2, but not MSH3, are responsible for hereditary non-polyposis colorectal cancer. To examine the role of MSH3, we generated a mouse with a null mutation in this gene. Cells from Msh3-/- mice are defective in repair of insertion/ deletion mismatches but can repair base-base mismatches. Msh3-/- mice develop tumors at a late age. When the Msh3-/- and Msh6-/- mutations are combined, the tumor predisposition phenotype is indistinguishable from Msh2-/- or Mlh1-/- mice. These results suggest that MSH3 cooperates with MSH6 in tumor suppression."
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Inhibition of RAS GTPases in Human Cancer
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RAS GTPases (H-, K-, and N-RAS) are the most frequently mutated oncoprotein family in human cancer. However, the relatively smooth surface architecture of RAS and its picomolar affinity for nucleotide have given rise to the assumption that RAS is an "undruggable" target. Recent advancements in drug screening, molecular modeling, and a greater understanding of RAS function have led to a resurgence in efforts to pharmacologically target this challenging foe. This review focuses on the state of the art of RAS inhibition, the approaches taken to achieve this goal, and the challenges of translating these discoveries into viable therapeutics.
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"We have used mouse embryonic fibroblasts (MEFs) devoid of Ras proteins to illustrate that they are essential for proliferation and migration, but not for survival, at least in these cells. These properties are unique to the Ras subfamily of proteins because ectopic expression of other Ras-like small GTPases, even when constitutively active, could not compensate for the absence of Ras proteins. Only constitutive activation of components of the Raf/Mek/Erk pathway was sufficient to sustain normal proliferation and migration of MEFs devoid of Ras proteins. Activation of the phosphatidylinositol 3-kinase (PI3K)/PTEN/Akt and Ral guanine exchange factor (RalGEF)/Ral pathways, either alone or in combination, failed to induce proliferation or migration of Rasless cells, although they cooperated with Raf/Mek/Erk signalling to reproduce the full response mediated by Ras signalling. In contrast to current hypotheses, Ras signalling did not induce proliferation by inducing expression of D-type Cyclins. Rasless MEFs had normal levels of Cyclin D1/Cdk4 and Cyclin E/Cdk2. However, these complexes were inactive. Inactivation of the pocket proteins or knock down of pRb relieved MEFs from their dependence on Ras signalling to proliferate.",
"Ras signalling has classically been thought to occur exclusively at the inner surface of a relatively uniform plasma membrane. Recent studies have shown that Ras proteins interact dynamically with specific microdomains of the plasma membrane as well as with other internal cell membranes. These different membrane microenvironments modulate Ras signal output and highlight the complex interplay between Ras location and function.",
"Ras proteins were originally identified as the products of oncogenes capable of inducing cell transformation. Over the last twenty-five years they have been studied in great detail because mutant Ras proteins are associated with many types of human cancer. Wild type Ras proteins play a central role in the regulation of proliferation and differentiation of various cell types. They alternate between an active GTP-bound state and an inactive GDP-bound state. Their activation is catalysed by a specialized group of enzymes known as guanine nucleotide exchange factors (GEFs). To date, four subfamilies of GEF molecules have been identified. Although all of them are able to activate Ras, their structure, tissue expression and regulation are significantly diverse. In this review we will summarize the various mechanisms by which these exchange factors activate Ras.",
"Genetic analysis of the RAS function in Caenorhabditis elegans has not only clarified the functional relationship of signal transduction proteins, but also led to the discovery of new proteins involved positively or negatively in RAS signaling. The stereotyped development of C. elegans has allowed many of the functions of RAS to be elucidated at the level of fates of individual cells.",
"Ras proteins participate as a molecular switch in the early steps of the signal transduction pathway that is associated with cell growth and differentiation. When the protein is in its GTP complexed form it is active in signal transduction, whereas it is inactive in its GDP complexed form. A comparison of eight three-dimensional structures of ras proteins in four different crystal lattices, five with a nonhydrolyzable GTP analog and three with GDP, reveals that the \"on\" and \"off\" states of the switch are distinguished by conformational differences that span a length of more than 40 A, and are induced by the gamma-phosphate. The most significant differences are localized in two regions: residues 30 to 38 (the switch I region) in the second loop and residues 60 to 76 (the switch II region) consisting of the fourth loop and the short alpha-helix that follows the loop. Both regions are highly exposed and form a continuous strip on the molecular surface most likely to be the recognition sites for the effector and receptor molecule(or molecules). The conformational differences also provide a structural basis for understanding the biological and biochemical changes of the proteins due to oncogenic mutations, autophosphorylation, and GTP hydrolysis, and for understanding the interactions with other proteins.",
"A combinatorial library of 6 × 106 cyclic peptides was synthesized in the one bead-two compound format, with each bead displaying a unique cyclic peptide on its surface and a linear peptide encoding tag in its interior. Screening of the library against K-Ras identified compounds that bound K-Ras with submicromolar affinity and disrupted its interaction with effector proteins.",
"A mutant rat cell clone that suppresses the transformation defects of RAS effector loop substitutions is heterozygous for mutations in c-raf1 and MEK1. The mutant cells can be transformed by many otherwise defective RAS effector mutants, including RAS genes with the effector regions of distantly related GTPases, even though the encoded RAS proteins do not interact with either the mutant or wild-type RAF in Saccharomyces cerevisiae. While the significance of the c-raf1 mutation is unclear, the MEK1 mutation increases MEK1 activity and leads to activation of mitogen-activated protein kinase. The mutant MEK1 is coupled to the epidermal growth factor pathway but exhibits decreased physical interaction with RAF. When overexpressed, the MEK1 mutation is transforming and causes hyperphosphorylation of RAF. Signalling from RAS to MEK1 may be mediated by something other than RAF alone, but signalling through MEK1 is probably sufficient for RAS transformation."
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Latent membrane protein 1 in nasopharyngeal carcinoma
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Latent membrane protein 1 (LMP1) is a primary oncogene encoded by the Epstein-Barr virus, and various portions of LMP1 are detected in nasopharyngeal carcinoma (NPC) tumor cells. LMP1 has been extensively studied since the discovery of its transforming property in 1985. LMP1 promotes cancer cell growth during NPC development and facilitates the interaction of cancer cells with surrounding stromal cells for invasion, angiogenesis, and immune modulation. LMP1 is detected in 100% of pre-invasive NPC tumors and in approximately 50% of advanced NPC tumors. Moreover, a small population of LMP1-expressing cells in advanced NPC tumor tissue is proposed to orchestrate NPC tumor tissue maintenance and development through cancer stem cells and progenitor cells. Recent studies suggest that LMP1 activity shifts according to tumor development stage, but it still has a pivotal role during all stages of NPC development.
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"MicroRNAs (miRNAs) have been implicated in sequence-specific cleavage, translational repression or deadenylation of specific target mRNAs resulting in post-transcriptional gene silencing. Epstein-Barr virus (EBV) encodes 23 miRNAs of unknown function. Here we show that the EBV-encoded miRNA miR-BART2 down-regulates the viral DNA polymerase BALF5. MiR-BART2 guides cleavage within the 3'-untranslated region (3'UTR) of BALF5 by virtue of its complete complementarity to its target. Induction of the lytic viral replication cycle results in a reduction of the level of miR-BART2 with a strong concomitant decrease of cleavage of the BALF5 3'UTR. Expression of miR-BART2 down-regulates the activity of a luciferase reporter gene containing the BALF5 3'UTR. Forced expression of miR-BART2 during lytic replication resulted in a 40-50% reduction of the level of BALF5 protein and a 20% reduction of the amount of virus released from EBV-infected cells. Our results are compatible with the notion that EBV-miR-BART2 inhibits transition from latent to lytic viral replication.",
"The importance of the malignant cell environment to its growth and survival is becoming increasingly apparent, with dynamic cross talk between the neoplastic cell, the leukocyte infiltrate and the stroma. Most cancers are accompanied by leukocyte infiltration which, contrary to an anticipated immuno-protective role, could be contributing to tumour development and cancer progression. Epstein-Barr virus (EBV) associated cancers, including nasopharyngeal carcinoma and Hodgkin's Disease, show a considerable leukocyte infiltration which surrounds the neoplastic cells, raising the questions as to what role these cells play in either restricting or supporting the tumour and what draws the cells into the tumour. In order to begin to address this we have studied a transgenic model of multistage carcinogenesis with epithelial expression of the EBV primary oncoprotein, latent membrane protein 1 (LMP1). LMP1 is expressed particularly in the skin, which develops a hyperplastic pathology soon after birth. The pathology advances with time leading to erosive dermatitis which is inflamed with a mixed infiltrate involving activated CD8+ T-cells, CD4+ T-cells including CD4+/CD25+/FoxP3+ Treg cells, mast cells and neutrophils. Also significant dermal deposition of immunoglobulin-G (IgG) is observed as the pathology advances. Along with NF-kappaB activation, STAT3, a central factor in inflammation regulation, is activated in the transgenic tissue. Several inflammatory factors are subsequently upregulated, notably CD30 and its ligand CD153, also leukocyte trafficking factors including CXCL10, CXCL13, L-selectin and TGFβ1, and inflammatory cytokines including IL-1β, IL-3 and the murine IL-8 analogues CXCL1, CXCL2 and CXCL5-6, amongst others. The crucial role of mature T- and/or B-lymphocytes in the advancing pathology is demonstrated by their elimination, which precludes mast cell infiltration and limits the pathology to an early, benign stage. LMP1 can lead to the activation of several key factors mediating proliferation, angiogenesis and inflammation in vivo. With the initiation of an inflammatory programme, leukocyte recruitment follows which then itself contributes to the progressing pathology in these transgenic mice, with a pivotal role for B-and/or T-cells in the process. The model suggests a basis for the leukocyte infiltrate observed in EBV-associated cancer and its supporting role, as well as potential points for therapeutic intervention.",
"Previous studies of Epstein-Barr virus (EBV) replication focused mainly on the viral and cellular factors involved in replication compartment assembly and controlling the cell cycle. However, little is known about how EBV reorganizes nuclear architecture and the chromatin territories. In EBV-positive nasopharyngeal carcinoma NA cells or Akata cells, we noticed that cellular chromatin becomes highly condensed upon EBV reactivation. In searching for the possible mechanisms involved, we found that transient expression of EBV BGLF4 kinase induces unscheduled chromosome condensation, nuclear lamina disassembly, and stress fiber rearrangements, independently of cellular DNA replication and Cdc2 activity. BGLF4 interacts with condensin complexes, the major components in mitotic chromosome assembly, and induces condensin phosphorylation at Cdc2 consensus motifs. BGLF4 also stimulates the decatenation activity of topoisomerase II, suggesting that it may induce chromosome condensation through condensin and topoisomerase II activation. The ability to induce chromosome condensation is conserved in another gammaherpesvirus kinase, murine herpesvirus 68 ORF36. Together, these findings suggest a novel mechanism by which gammaherpesvirus kinases may induce multiple premature mitotic events to provide more extrachromosomal space for viral DNA replication and successful egress of nucleocapsid from the nucleus.",
"Latent infection with Epstein-Barr virus (EBV) is responsible for multiple types of malignancies, including 10% of all gastric carcinomas. The microRNA (miRNA) expression in several EBV-infected AGS gastric carcinoma cell lines was determined. Infected cells expressed the viral BamHI A rightward transcript (BART) miRNAs at high levels and had consistently decreased expression of a small fraction of cellular miRNAs with specific downregulation of tumor suppressor miRNAs. These changes likely reflect expression of the viral noncoding RNAs and not latent protein expression.",
"The close association of Epstein-Barr virus (EBV) infection with non-keratinizing nasopharyngeal carcinomas and a subset of gastric carcinomas suggests that EBV infection is a crucial event in these cancers. The difficulties encountered in infecting and transforming primary epithelial cells in experimental systems suggest that the role of EBV in epithelial malignancies is complex and multifactorial in nature. Genetic alterations in the premalignant epithelium may support the establishment of latent EBV infection, which is believed to be an initiation event. Oncogenic properties have been reported in multiple EBV latent genes. The BamH1 A rightwards transcripts (BARTs) and the BART-encoded microRNAs (miR-BARTs) are highly expressed in EBV-associated epithelial malignancies and may induce malignant transformation. However, enhanced proliferation may not be the crucial function of EBV infection in epithelial malignancies, at least in the early stages of cancer development. EBV-encoded gene products may confer anti-apoptotic properties and promote the survival of infected premalignant epithelial cells harbouring genetic alterations. Multiple EBV-encoded microRNAs have been reported to have immune evasion functions. Genetic alterations in host cells, as well as inflammatory stroma, could modulate the expression of EBV genes and alter the growth properties of infected premalignant epithelial cells, encouraging their selection during carcinogenesis.",
"Cyclooxygenase-2 (COX-2) is an inducible form of COX and is overexpressed in diverse tumors, raising the possibility of a role for COX-2 in carcinogenesis. In addition, COX-2 contributes to angiogenesis. The Epstein-Barr virus (EBV) oncoprotein, latent membrane protein 1 (LMP1), is detected in at least 70% of nasopharyngeal carcinoma (NPC) and all EBV-infected preinvasive nasopharyngeal lesions. We found that in specimens of LMP1-positive NPC, COX-2 is frequently expressed, whereas LMP1-negative NPC rarely express the enzyme. We next found that expression of LMP1 in EBV-negative nasopharyngeal epithelial cells induced COX-2 expression. Coexpression of IkappaBalpha(S32A/S36A), which is not phosphorylated and prevents NF-kappaB activation, with LMP1 showed that NF-kappaB is essential for induction of COX-2 by LMP1. We also demonstrate that NF-kappaB is involved in LMP1-induced cox-2 promoter activity with the use of reporter assays. Two major regions of LMP1, designated CTAR1 and CTAR2, are signal-transducing domains of LMP1. Constructs expressing either CTAR1 or CTAR2 induce COX-2 but to a lesser extent than wild-type LMP1, consistent with the ability of both regions to activate NF-kappaB. Furthermore, we demonstrate that LMP1-induced COX-2 is functional because LMP1 increased production of prostaglandin E(2) in a COX-2-dependent manner. Finally, we demonstrate that LMP1 increased production of vascular endothelial growth factor (VEGF). Treatment of LMP1-expressing cells with the COX-2-specific inhibitor (NS-398) dramatically decreased production of VEGF, suggesting that LMP1-induced VEGF production is mediated, at least in part, by COX-2. These results suggest that COX-2 induction by LMP1 may play a role in angiogenesis in NPC.",
"Epstein-Barr virus (EBV) infection contributes to the development of several different types of human malignancy, including Burkitt lymphoma, Hodgkin lymphoma, and nasopharyngeal carcinoma. As a herpesvirus, EBV can establish latent or lytic infection in cells. EBV-positive tumors are composed almost exclusively of cells with latent EBV infection. Strategies for inducing the lytic form of EBV infection in tumor cells are being investigated as a potential therapy for EBV-positive tumors. In this article, we review how cellular and viral proteins regulate the latent-lytic EBV switch in infected B cells and epithelial cells, and discuss how harnessing lytic viral reactivation might be used therapeutically.",
"EBV has been associated with nasopharyngeal carcinomas (NPC). In North Africa, the incidence is bimodal-the first peak occurring at approximately 20 years of age and the second peak occurring at approximately 50 years. Standard diagnostic tests based on immunofluorescence using anti-IgA EBV have shown that young North African patients have a negative serology compared with older patients. We are interested in two EBV-encoded oncoproteins, LMP1 and BARF1, which have thus far not been studied in terms of their potential as diagnostic markers for NPC. These two viral oncoproteins have been detected in cell culture media, so we tested whether they could be detected in the serum and saliva of patients with NPC. LMP1 and BARF1 proteins were analyzed in the sera and saliva of young patients and adult patients with NPC from North Africa and China. We then examined whether the secreted proteins had biological activity by analyzing their mitogenic activity. Both LMP1 and BARF1 were present in the serum and saliva from North African and Chinese patients with NPC. All young North African patients secreted both proteins, whereas 62% and 100% of adult patients secreted LMP1 and BARF1, respectively. From animal studies, the secreted LMP1 was associated with exosome-like vesicles. These secreted EBV oncoproteins showed a powerful mitogenic activity in B cells. Both proteins will be a good diagnostic marker for NPC whereas BARF1 is a particularly promising marker for all ages of patients with NPC. Their mitogenic activity suggests their implication in the oncogenic development of NPC.",
"Epstein-Barr virus (EBV) was the first human virus found to encode microRNAs (miRNAs), but the function of these miRNAs has been obscure. Nasopharyngeal carcinoma (NPC) is associated with EBV infection, and the EBV-encoded LMP1 is believed to be a key factor in NPC development. However, detection of LMP1 protein in NPC is variable. Here, we report that EBV-encoded BART miRNAs target the 3' UTR of the LMP1 gene and negatively regulate LMP1 protein expression. These miRNAs also modulate LMP1-induced NF-kappaB signaling and alleviate the cisplatin sensitivity of LMP1-expressing NPC cells. Consistent with a previous study on the NPC C666-1 cell line and C15 xenograft, we found abundant expression of BART miRNAs in NPC tissues. Furthermore, DNA sequencing revealed that the 3' UTR of LMP1 is highly conserved in NPC-derived EBV isolates. The data provide insight into the discrepancy between LMP1 transcript and protein detection in NPC and highlight the role of the EBV miRNAs in regulating LMP1 downstream signaling to promote cancer development.",
"The EBV-encoded EBNA1 was first discovered 40 years ago, approximately 10 years after the presence of EBV had been demonstrated in Burkitt's lymphoma cells. It took another 10 years before the functions of EBNA1 in maintaining the viral genome were revealed, and it has since been shown to be an essential viral factor expressed in all EBV-carrying cells. Apart from serving to maintain the viral episome and to control viral replication and gene expression, EBNA1 also harbours a cis-acting mechanism that allows virus-carrying host cells to evade the immune system. This relates to a particular glycine-alanine repeat (GAr) within EBNA1 that has the capacity to suppress antigen presentation to the major histocompatibility complex (MHC) class I pathway. We discuss the role of the GAr sequence at the level of mRNA translation initiation, rather than at the protein level, as at least part of the mechanism to avoid MHC presentation. Interfering with this mechanism has become the focus of the development of immune-based therapies against EBV-carrying cancers, and some lead compounds that affect translation of GAr-carrying mRNAs have been identified. In addition, we describe the EBV-encoded ZEBRA factor and the switch from the latent to the lytic cycle as an alternative virus-specific target for treating EBV-carrying cancers. Understanding the molecular mechanisms of how EBNA1 and ZEBRA interfere with cellular pathways not only opens new therapeutic approaches but continues to reveal new cell-biological insights on the interplay between host and virus. This review is a tale of discoveries relating to how EBNA1 and ZEBRA have emerged as targets for specific cancer therapies against EBV-carrying diseases, and serves as an illustration of how mRNA translation can play roles in future immune-based strategies to target viral disease."
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Streptococcus pyogenes Cas9-mediated genome editing and knockout of vascular endothelial growth factor A in mice
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Virus-based gene therapy by CRISPR/Cas9-mediated genome editing and knockout may provide a new option for treatment of inherited and acquired ocular diseases of the retina. In support of this notion, we show that Streptococcus pyogenes (Sp) Cas9, delivered by lentiviral vectors (LVs), can be used in vivo to selectively ablate the vascular endothelial growth factor A (Vegfa) gene in mice. By generating LVs encoding SpCas9 targeted to Vegfa, and in parallel the fluorescent eGFP marker protein, we demonstrate robust knockout of Vegfa that leads to a significant reduction of VEGFA protein in transduced cells. Three of the designed single-guide RNAs (sgRNAs) induce in vitro indel formation at high frequencies (44%-93%). A single unilateral subretinal injection facilitates RPE-specific localization of the vector and disruption of Vegfa in isolated eGFP
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"Ischemia often precedes neovascularization. In ocular neovascularization, such as occurs in diabetic retinopathy, a diffusible angiogenic factor has been postulated to be produced by ischemic retina and to lead to neovascularization of the retina, optic nerve, or iris. However, no angiogenic factor has been conclusively identified that satisfies this hypothesis. Vascular endothelial growth factor/vascular permeability factor, hereafter referred to as VEGF, is a likely candidate for an ocular angiogenic factor because it is a secreted mitogen, specific for endothelial cells, and is upregulated by hypoxia. We investigated the association of VEGF with the development of experimental iris neovascularization in the cynomolgus monkey. Following the production of retinal ischemia by laser occlusion of all branch retinal veins, VEGF was increased in the aqueous fluid, and the aqueous VEGF levels changed synchronously and proportionally with the severity of iris neovascularization. Northern analysis and in situ hybridization revealed that VEGF messenger RNA is upregulated in the ischemic retina. These observations support the hypothesis that ocular neovascularization is regulated by a diffusible factor and identify VEGF as a likely candidate for a retina-derived vascular permeability and angiogenesis factor in vivo.",
"Recombinant adeno-associated viral (AAV) vectors have become powerful gene delivery tools for the treatment of retinal degeneration in a variety of animal models that mimic corresponding human diseases. AAV vectors possess a number of features that render them ideally suited for retinal gene therapy, including a lack of pathogenicity, minimal immunogenicity, and the ability to transduce postmitotic cells in a stable and efficient manner. In the sheltered environment of the retina, AAV vectors are able to maintain high levels of transgene expression in the retinal pigmented epithelium (RPE), photoreceptors, or ganglion cells for long periods of time after a single treatment. Each cell type can be specifically targeted by choosing the appropriate combination of AAV serotype, promoter, and intraocular injection site. The focus of this review is on examples of AAV-mediated gene therapy in those animal models of inherited retinal degeneration caused by mutations directly affecting the interacting unit formed by photoreceptors and the RPE. In each case discussed, expression of the therapeutic gene resulted in significant recovery of retinal structure and/or visual function. Because of the key role of the vasculature in maintaining a healthy retina, a summary of AAV gene therapy applications in animal models of retinal neovascular diseases is also included.",
"The congenital retinal blindness known as Leber congenital amaurosis (LCA) can be caused by mutations in the RPE65 gene. RPE65 plays a critical role in the visual cycle that produces the photosensitive pigment rhodopsin. Recent evidence from human studies of LCA indicates that earlier rather than later intervention may be more likely to restore vision. We determined the impact of in utero delivery of the human RPE65 cDNA to retinal pigment epithelium cells in a murine model of LCA, the Rpe65(-/-) mouse, using a serotype 2 adeno-associated virus packaged within an AAV1 capsid (AAV2/1). Delivery of AAV2/1-CMV-hRPE65 to fetuses (embryonic day 14) resulted in efficient transduction of retinal pigment epithelium, restoration of visual function, and measurable rhodopsin. The results demonstrate AAV-mediated correction of the deficit and suggest that in utero retinal gene delivery may be a useful approach for treating a variety of blinding congenital retinal diseases.",
"We demonstrate CRISPR-Cas9-mediated correction of a Fah mutation in hepatocytes in a mouse model of the human disease hereditary tyrosinemia. Delivery of components of the CRISPR-Cas9 system by hydrodynamic injection resulted in initial expression of the wild-type Fah protein in ∼1/250 liver cells. Expansion of Fah-positive hepatocytes rescued the body weight loss phenotype. Our study indicates that CRISPR-Cas9-mediated genome editing is possible in adult animals and has potential for correction of human genetic diseases.",
"RPE65 is essential for isomerization of vitamin A to the visual chromophore. Mutations in RPE65 cause early-onset blindness, and Rpe65-deficient mice lack 11-cis-retinal but overaccumulate alltrans-retinyl esters in the retinal pigment epithelium (RPE). RPE65 is proposed to be a substrate chaperone but may have an enzymatic role because it is closely related to carotenoid oxygenases. We hypothesize that, by analogy with other carotenoid oxygenases, the predicted iron-coordinating residues of RPE65 are essential for retinoid isomerization. To clarify RPE65's role in isomerization, we reconstituted a robust minimal visual cycle in 293-F cells. Only cells transfected with RPE65 constructs produced 11-cis-retinoids, but coexpression with lecithin:retinol acyltransferase was needed for high-level production. Accumulation was significant, amounting to >2 nmol of 11-cis-retinol per culture. Transfection with constructs harboring mutations in residues of RPE65 homologous to those required for interlinked enzymatic activity and iron coordination in related enzymes abolish this isomerization. Iron chelation also abolished isomerization activity. Mutating cysteines implicated in palmitoylation of RPE65 had generally little effect on isomerization activity. Mutations associated with Leber congenital amaurosis/early-onset blindness cause partial to total loss of isomerization activity in direct relation to their clinical effects. These findings establish a catalytic role, in conjunction with lecithin:retinol acyltransferase, for RPE65 in synthesis of 11-cis-retinol, and its identity as the isomerohydrolase.",
"RPE65 is specifically expressed in the retinal pigment epithelium and is essential for the recycling of 11-cis-retinal, the chromophore of rod and cone opsins. In humans, mutations in RPE65 lead to Leber congenital amaurosis or early-onset retinal dystrophy, a severe form of retinitis pigmentosa. The proof of feasibility of gene therapy for RPE65 deficiency has already been established in a dog model of Leber congenital amaurosis, but rescue of the cone function, although crucial for human high-acuity vision, has never been strictly proven. In Rpe65 knockout mice, photoreceptors show a drastically reduced light sensitivity and are subject to degeneration, the cone photoreceptors being lost at early stages of the disease. In the present study, we address the question of whether application of a lentiviral vector expressing the Rpe65 mouse cDNA prevents cone degeneration and restores cone function in Rpe65 knockout mice. Subretinal injection of the vector in Rpe65-deficient mice led to sustained expression of Rpe65 in the retinal pigment epithelium. Electroretinogram recordings showed that Rpe65 gene transfer restored retinal function to a near-normal pattern. We performed histological analyses using cone-specific markers and demonstrated that Rpe65 gene transfer completely prevented cone degeneration until at least four months, an age at which almost all cones have degenerated in the untreated Rpe65-deficient mouse. We established an algorithm that allows prediction of the cone-rescue area as a function of transgene expression, which should be a useful tool for future clinical trials. Finally, in mice deficient for both RPE65 and rod transducin, Rpe65 gene transfer restored cone function when applied at an early stage of the disease. By demonstrating that lentivirus-mediated Rpe65 gene transfer protects and restores the function of cones in the Rpe65(-/-) mouse, this study reinforces the therapeutic value of gene therapy for RPE65 deficiencies, suggests a cone-preserving treatment for the retina, and evaluates a potentially effective viral vector for this purpose.",
"RPE65 is essential for the generation of 11-cis retinal. Rod photoreceptors in the RPE65-knockout (Rpe65(-/-)) mouse are known to degenerate slowly with age. This study was designed to examine cone photoreceptors and the expression of cone-specific genes in the Rpe65(-/-) mouse. Gene expression changes were identified by microarray and confirmed by real-time RT-PCR. Cone photoreceptors were stained by peanut agglutinin (PNA) lectin in the flatmounted retina. The 9- or 11-cis retinal was supplied by intraperitoneal injections. The short-wavelength (SWL) cone opsin mRNA was markedly decreased at 2 weeks of age, whereas the decrease in the middle-wavelength (MWL) cone opsin mRNA occurred relatively later in age. In contrast, the rhodopsin mRNA level did not show any significant change at all the ages analyzed. Consistent with the cone opsin changes, the cone transducin alpha-subunit mRNA decreased at both 4 and 8 weeks of age, whereas again the rod transducin alpha-subunit did not show any significant change. Rpe65(-/-) mice showed significant cone loss in both the central and ventral retina between 2 and 3 weeks of age. Administration of 9- or 11-cis retinal to Rpe65(-/-) mice 2 weeks of age increased cone density by twofold in these areas. In the Rpe65(-/-) mouse, the expression of cone-specific genes is downregulated and is accompanied by cone degeneration at early ages. Early administration of 9- or 11-cis retinal can partially prevent cone loss, suggesting that the absence of 11-cis chromophore may be responsible for the early cone degeneration."
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Untargeted Lipidomics of Daptomycin-Susceptible and-Resistant Isogenic Strain Pairs
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Previous work suggests that altered lipid metabolism may be associated with daptomycin resistance in Gram-positive pathogens, but lipidomic changes underlying resistance are not fully understood. We performed untargeted lipidomics by using three-dimensional hydrophilic interaction liquid chromatography-ion mobility-mass spectrometry (HILIC-IM-MS) to characterize alterations in the lipidomes of daptomycin-susceptible and -resistant isogenic strain pairs of
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"The electrical potential (delta psi) across the cytoplasmic membranes of Staphylococcus aureus cells growing under aerobic and anaerobic conditions was determined by measuring the equilibrium distribution of [3H]tetraphenyl phosphonium. In conjunction, gentamicin uptake and killing were studied in the same cells under identical conditions. Under aerobic conditions, delta psi was -169 mV, gentamicin uptake was readily demonstrable, and the number of viable cells decreased by almost four orders of magnitude in the presence of antibiotic. In contrast, delta psi was -142 mV anaerobically, gentamicin uptake was essentially nonexistent, and the aminoglycoside had no effect on viability. Remarkably, when the ionophore nigericin was added under anaerobic conditions, delta psi increased to the level observed aerobically, gentamicin uptake tripled to about 18% of the aerobic level, and viability decreased by one order of magnitude. The results are consistent with other observations (Mates et al., Proc. Natl. Acad. Sci. U.S.A. 79:6693-6697, 1982), indicating that the relationship between delta psi and gentamicin uptake is gated, and suggest that diminution of delta psi may be an important factor in aminoglycoside resistance under anaerobic conditions.",
"We studied the in vitro emergence of resistance to daptomycin using three methods: spontaneous resistance incidence, serial passage in the presence of increasing drug concentrations, and chemical mutagenesis. No spontaneously resistant mutants were obtained for any organism tested (<10(-10) for Staphylococcus aureus, <10(-9) for Staphylococcus epidermidis, <10(-9) for Enterococcus faecalis, <10(-9) for Enterococcus faecium, <10(-8) for Streptococcus pneumoniae). Population analysis demonstrated that bacterial susceptibility to daptomycin is heterogeneous. Assay results were sensitive to calcium concentration and culture density, both of which can affect apparent resistance rates. Stable S. aureus mutants were isolated by both serial passage in liquid media and chemical mutagenesis. The daptomycin MICs for these isolates were 8- to 32-fold higher than for the parental strain. Many mutants with high MICs (>12.5 microg/ml) had significant growth defects but did not display phenotypes typical of S. aureus small colony variants. The voltage component (Delta psi) of the bacterial membrane potential was increased in three independent resistant isolates. In vivo data showed that some daptomycin-resistant mutants had lost significant virulence. For other mutants, the degree of in vitro resistance was greater than the change in in vivo susceptibility. These results suggest that infection with some daptomycin-resistant organisms may still be easily treatable.",
"Cell wall thickening is a common feature among daptomycin-resistant Staphylococcus aureus strains. However, the mechanism(s) leading to this phenotype is unknown. We examined a number of cell wall synthesis pathway parameters in an isogenic strain set of S. aureus bloodstream isolates obtained from a patient with recalcitrant endocarditis who failed daptomycin therapy, including the initial daptomycin-susceptible parental strain (strain 616) and two daptomycin-resistant strains (strains 701 and 703) isolated during daptomycin therapy. Transmission electron microscopy demonstrated significantly thicker cell walls in the daptomycin-resistant strains than in the daptomycin-susceptible strain, a finding which was compatible with significant differences in dry cell weight of strain 616 versus strains 701 to 703 (P < 0.05). Results of detailed analysis of cell wall muropeptide composition, the degree of peptide side chain cross-linkage, and the amount of the peptidoglycan precursor, UDP-MurNAc-pentapeptide, were similar in the daptomycin-susceptible and daptomycin-resistant isolates. In contrast, the daptomycin-resistant strains contained less O-acetylated peptidoglycan. Importantly, both daptomycin-resistant strains synthesized significantly more wall teichoic acid (WTA) than the parental strain (P < 0.001). Moreover, the proportion of D-alanylated WTA species was substantially higher in the daptomycin-resistant strains than in the daptomycin-susceptible parental strain (P < 0.05 in comparing strain 616 versus strain 701). The latter phenotypic findings correlated with (i) enhanced tagA and dltA gene expression, respectively, and (ii) an increase in surface positive charge observed in the daptomycin-resistant versus daptomycin-susceptible isolates. Collectively, these data suggest that increases in WTA synthesis and the degree of its D-alanylation may play a major role in the daptomycin-resistant phenotype in some S. aureus strains.",
"The phenotypic expression of methicillin resistance was studied in a number of clinical isolates and laboratory strains of Staphylococcus aureus. The methicillin-resistant S. aureus strains could be divided into three classes, homogeneous, heterogeneous, and thermosensitive heterogeneous methicillin-resistant S. aureus, on the basis of their plating efficiencies at 30 or 37 degrees C on methicillin-containing agar plates. Heterogeneous strains of methicillin-resistant S. aureus were composed of two subpopulations: a small minority of cells (10(-5) to 10(-3); MIC, 600 to 1,000 micrograms/ml) that expressed resistance to high concentrations of methicillin at 37 degrees C, and a majority of cells (MIC, 5 micrograms/ml) that remained susceptible to the drug at 37 degrees C. Cultures of a thermosensitive heterogeneous strain were able to grow in the presence of high concentrations of methicillin, provided that the growth temperature was 30 degrees C. Such cultures lost their phenotypic resistance within 30 min (i.e., in less than one doubling time) after the growth temperature was shifted to the nonpermissive 37 degrees C. Shift of the temperature of the culture in the reverse direction (37 to 30 degrees C) resulted in an equally rapid expression of phenotypic resistance. The majority of the cells in such heterogeneous strains may be considered heat (or salt) conditional in their phenotypic expression of methicillin resistance. Both heterogeneous and thermosensitive heterogeneous strains, irrespective of their temperature of cultivation and degree of phenotypic resistance, contained detectable quantities of the 78-kilodalton penicillin-binding protein 2a (PBP 2a) that previous studies have suggested is a biochemical correlate of methicillin resistance in homogeneous strains of methicillin-resistant S. aureus. However, in contrast to the homogeneous stains, in heterogeneous and thermosensitive heterogeneous isolates the ability to synthesize PBP 2a is apparently not sufficient to provide a resistant phenotype. In these strains some additional, as yet undefined factor(s) is also needed for the expression of methicillin resistance.",
"MprF is responsible for the lysinylation of phosphatidylglycerol (PG) to synthesize the positively charged phospholipid (PL) species, lysyl-PG (L-PG). It has been proposed that the single-nucleotide polymorphisms (SNPs) within the mprF open reading frame (ORF) are associated with a gain-in-function phenotype in terms of daptomycin resistance in Staphylococcus aureus. (Note that although the official term is daptomycin nonsusceptibility, we use the term daptomycin resistance in this paper for ease of presentation.) Using 22 daptomycin-susceptible (DAP(s))/daptomycin-resistant (DAP(r)) clinical methicillin-resistant S. aureus (MRSA) strain pairs, we assessed (i) the frequencies and distribution of putative mprF gain-in-function SNPs, (ii) the relationships of the SNPs to both daptomycin resistance and cross-resistance to the prototypical endovascular host defense peptide (HDP) thrombin-induced platelet microbicidal protein (tPMP), and (iii) the impact of mprF SNPs on positive surface charge phenotype and modifications of membrane PL profiles. Most of the mprF SNPs identified in our DAP(r) strains were clustered within the two MprF loci, (i) the central bifunctional domain and (ii) the C-terminal synthase domain. Moreover, we were able to correlate the presence and location of mprF SNPs in DAP(r) strains with HDP cross-resistance, positive surface charge, and L-PG profiles. Although DAP(r) strains with mprF SNPs in the bifunctional domain showed higher resistance to tPMPs than DAP(r) strains with SNPs in the synthase domain, this relationship was not observed in positive surface charge assays. These results demonstrated that both charge-mediated and -unrelated mechanisms are involved in DAP resistance and HDP cross-resistance in S. aureus.",
"Daptomycin is a cyclic anionic lipopeptide antibiotic recently approved for the treatment of complicated skin infections (Cubicin). Its function is dependent on calcium (as Ca2+). Circular dichroism spectroscopy indicated that daptomycin experienced two structural transitions: a transition upon interaction of daptomycin with Ca2+, and a further transition upon interaction with Ca2+ and the bacterial acidic phospholipid, phosphatidyl glycerol. The Ca2+-dependent insertion of daptomycin into model membranes promoted mild and more pronounced perturbations as assessed by the increase of lipid flip-flop and membrane leakage, respectively. The NMR structure of daptomycin indicated that Ca2+ induced a conformational change in daptomycin that increased its amphipathicity. These results are consistent with the hypothesis that the association of Ca2+ with daptomycin permits it to interact with bacterial membranes with effects that are similar to those of the cationic antimicrobial peptides.",
"Using isogenic clinical bloodstream Staphylococcus aureus strains from a patient with relapsing endocarditis, we investigated the transcriptional profiles of the mprF and dlt genes in the context of cell-surface charge and daptomycin nonsusceptibility. As in prior studies, a point mutation within mprF was observed in the daptomycin-nonsusceptible strain. However, neither the transcriptional profile of mprF nor the membrane phospholipid analyses were compatible with the anticipated mprF gain-in-function phenotype. In contrast, we demonstrated enhanced dlt expression coincident with increased positive surface charge and reduced daptomycin binding.",
"Daptomycin (DAP) is a cyclic lipopeptide that disrupts the functional integrity of the cell membranes of Gram-positive bacteria in a Ca(2+)-dependent manner. Here we present genetic, genomic, and phenotypic analyses of an evolved DAP-resistant isolate, Dap(R)1, from the model bacterium Bacillus subtilis 168. Dap(R)1 was obtained by serial passages with increasing DAP concentrations, is 30-fold more resistant than the parent strain, and displays cross-resistance to vancomycin, moenomycin, and bacitracin. Dap(R)1 is characterized by aberrant septum placement, notably thickened peptidoglycan at the cell poles, and pleiotropic alterations at both the transcriptome and proteome levels. Genome sequencing of Dap(R)1 revealed 44 point mutations, 31 of which change protein sequences. An intermediate isolate that was 20-fold more resistant to DAP than the wild type had only three of these point mutations: mutations affecting the cell shape modulator gene mreB, the stringent response gene relA, and the phosphatidylglycerol synthase gene pgsA. Genetic reconstruction studies indicated that the pgsA(A64V) allele is primarily responsible for DAP resistance. Allelic replacement with wild-type pgsA restored DAP sensitivity to wild-type levels. The additional point mutations in the evolved strain may contribute further to DAP resistance, serve to compensate for the deleterious effects of altered membrane composition, or represent neutral changes. These results suggest a resistance mechanism by which reduced levels of phosphatidylglycerol decrease the net negative charge of the membrane, thereby weakening interaction with the positively charged Ca(2+)-DAP complex.",
"The in vitro activity of daptomycin was compared with those of vancomycin, linezolid, and quinupristin-dalfopristin against a variety (n = 203) of gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and S. epidermidis (MRSA and MRSE, respectively), vancomycin-resistant enterococci (VRE), and vancomycin-intermediate S. aureus (VISA). Overall, daptomycin was more active against all organisms tested, except Enterococcus faecium and VISA, against which its activity was similar to that of quinupristin-dalfopristin. In time-kill studies with MRSA, MRSE, VRE, and VISA, daptomycin demonstrated greater bactericidal activity than all other drugs tested, killing > or =3 log CFU/ml by 8 h. Daptomycin may be a potential alternative drug therapy for multidrug-resistant gram-positive organisms and warrants further investigation.",
"Untargeted metabolomics provides a comprehensive platform for identifying metabolites whose levels are altered between two or more populations. By using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS), hundreds to thousands of peaks with a unique m/z ratio and retention time are routinely detected from most biological samples in an untargeted profiling experiment. Each peak, termed a metabolomic feature, can be characterized on the basis of its accurate mass, retention time and tandem mass spectral fragmentation pattern. Here a seven-step protocol is suggested for such a characterization by using the METLIN metabolite database. The protocol starts from untargeted metabolomic LC-Q-TOF-MS data that have been analyzed with the bioinformatics program XCMS, and it describes a strategy for selecting interesting features as well as performing subsequent targeted tandem MS. The seven steps described will require 2-4 h to complete per feature, depending on the compound."
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Chemical modification of 2'-deoxyinosine and D-/L-isothymidine on AS1411 promotes the nucleotide-protein interaction.
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In this study, chemical modification of 2'-deoxyinosine (2'-dI) and D-/L-isothymidine (D-/L-isoT) was performed on AS1411. They could promote the nucleotide-protein interaction by changing the local conformation. Twenty modified sequences were obtained, FCL-I and FCL-II showed the most noticeable activity improvement. They stabilized the G-quadruplex, remained highly resistant to serum degradation and specificity for nucleolin, further inhibited tumor cell growth, exhibited a stronger ability to influence the different phases of the tumor cell cycle, induced S-phase arrest, promoted the inhibition of DNA replication, and suppressed the unwound function of a large T antigen as powerful as AS1411. The microarray analysis and TaqMan PCR results showed that FCL-II can upregulate the expression of four breast-cancer-related, lowly expressed miRNAs and downregulate the expression of three breast-cancer-related, highly expressed miRNAs (>2.5-fold). FCL-II resulted in enhanced treatment effects greater than AS1411 in animal experiments (p < 0.01). The computational results further proved that FCL-II exhibits more structural advantages than AS1411 for binding to the target protein nucleolin, indicating its great potential in antitumor therapy.
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"Nucleic-acid aptamers have the molecular recognition properties of antibodies, and can be isolated robotically for high-throughput applications in diagnostics, research and therapeutics. Unlike antibodies, however, they can be chemically derivatized easily to extend their lifetimes in biological fluids and their bioavailability in animals. The first aptamer-based clinical drugs have recently entered service. Meanwhile, active research programmes have identified a wide range of anti-viral aptamers that could form the basis for future therapeutics.",
"We describe a novel activity of the SV40 large T-ag helicase, the unwinding of four stranded DNA structures linked by stacked G-quartets, namely stacked groups of four guanine bases bound by Hoogsteen hydrogen bonds. The structures unwound by the helicase were of two types: (i) quadruplexes comprising four parallel strands that were generated by annealing oligonucleotides including clustered G residues in a buffer containing Na+ions. Each parallel quadruplex consisted of four oligonucleotide molecules. (ii) Complexes comprising two parallel and two antiparallel strands that were generated by annealing the above oligonucleotides in a buffer containing K+ions. Each antiparallel complex consisted of two folded oligonucleotide molecules. Unwinding of these unusual DNA structures by the T-ag was monitored by gel electrophoresis. The unwinding process required ATP and at least one single stranded 3'-tail extending beyond the four stranded region. These data indicated that the T-ag first binds the 3'-tail and moves in a 3'-->5'direction, using energy provided by ATP hydrolysis; then it unwinds the four stranded DNA into single strands. This helicase activity may affect processes such as recombination and telomere extension, in which four stranded DNA could play a role.",
"Single molecule detection methods, such as nanopore sensors have found increasing importance in applications ranging from gaining a better understanding of biophysical processes to technology driven solutions such as DNA sequencing. However, challenges remain especially in relation to improving selectivity to probe specific targets or to alternatively enable detection of smaller molecules such as small-sized proteins with a sufficiently high signal-to-noise ratio. In this article, we propose a solution to these technological challenges by using DNA aptamer-modified gold nanoparticles (AuNPs) that act as a molecular carrier through the nanopore sensor. We show that this approach offers numerous advantages including: high levels of selectivity, efficient capture from a complex mixture, enhanced signal, minimized analyte-sensor surface interactions, and finally can be used to enhance the event detection rate. This is demonstrated by incorporating a lysozyme binding aptamer to a 5 nm AuNP carrier to selectively probe lysozyme within a cocktail of proteins. We show that nanopores can reveal sub-complex molecular information, by discriminating the AuNP from the protein analyte, indicating the potential use of this technology for single molecule analysis of different molecular analytes specifically bound to AuNP.",
"AS1411 is a quadruplex-forming oligonucleotide aptamer that targets nucleolin. It is currently in clinical trials as a treatment for various cancers. We have proposed that AS1411 inhibits cancer cell proliferation by affecting the activities of certain nucleolin-containing complexes. Here, we report that protein arginine methyltransferase 5 (PRMT5), an enzyme that catalyzes the formation of symmetrical dimethylarginine (sDMA), is a nucleolin-associated protein whose localization and activity are altered by AS1411. Levels of PRMT5 were found to be decreased in the nucleus of AS1411-treated DU145 human prostate cancer cells, but increased in the cytoplasm. These changes were dependent on nucleolin and were not observed in cells pretreated with nucleolin-specific small interfering RNA. Treatment with AS1411 altered levels of PRMT5 activity (assessed by sDMA levels) in accord with changes in its localization. In addition, our data indicate that nucleolin itself is a substrate for PRMT5 and that distribution of sDMA-modified nucleolin is altered by AS1411. Because histone arginine methylation by PRMT5 causes transcriptional repression, we also examined expression of selected PRMT5 target genes in AS1411-treated cells. For some genes, including cyclin E2 and tumor suppressor ST7, a significant up-regulation was noted, which corresponded with decreased PRMT5 association with the gene promoter. We conclude that nucleolin is a novel binding partner and substrate for PRMT5, and that AS1411 causes relocalization of the nucleolin-PRMT5 complex from the nucleus to the cytoplasm. Consequently, the nuclear activity of PRMT5 is decreased, leading to derepression of some PRMT5 target genes, which may contribute to the biological effects of AS1411.",
"Established methods for characterizing proteins typically require physical or chemical modification steps or cannot be used to examine individual molecules in solution. Ionic current measurements through electrolyte-filled nanopores can characterize single native proteins in an aqueous environment, but currently offer only limited capabilities. Here we show that the zeptolitre sensing volume of bilayer-coated solid-state nanopores can be used to determine the approximate shape, volume, charge, rotational diffusion coefficient and dipole moment of individual proteins. To do this, we developed a theory for the quantitative understanding of modulations in ionic current that arise from the rotational dynamics of single proteins as they move through the electric field inside the nanopore. The approach allows us to measure the five parameters simultaneously, and we show that they can be used to identify, characterize and quantify proteins and protein complexes with potential implications for structural biology, proteomics, biomarker detection and routine protein analysis.",
"The in vitro selection of nucleic acid binding species (aptamers) is frequently repetitive, time-consuming, and poorly adapted to high-throughput applications. We have adapted automated workstations to select anti-protein aptamers; as an example, we demonstrated the selection of anti-lysozyme aptamers that function as efficient inhibitors of cell lysis. The increases in throughput brought about by automation should potentiate the application of aptamer technology to the rapidly growing field of proteomics.",
"Electrospray ionization has recently emerged as a powerful technique for producing intact ions in vacuo from large and complex species in solution. To an extent greater than has previously been possible with the more familiar \"soft\" ionization methods, this technique makes the power and elegance of mass spectrometric analysis applicable to the large and fragile polar molecules that play such vital roles in biological systems. The distinguishing features of electrospray spectra for large molecules are coherent sequences of peaks whose component ions are multiply charged, the ions of each peak differing by one charge from those of adjacent neighbors in the sequence. Spectra have been obtained for biopolymers including oligonucleotides and proteins, the latter having molecular weights up to 130,000, with as yet no evidence of an upper limit."
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Innate IL4-producing cells in the immune regulation of allergy
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Basophils are circulating cells that are associated quite exclusively with allergy response and hypersensitivity reactions but their role in the immune network might be much more intriguing and complex than previously expected. The feasibility of testing their biology in vitro for allergy research and diagnosis, due fundamentally to their quite easy availability in the peripheral blood, made them the major source for assessing allergy in the laboratory assay, when yet many further cells such as mast cells and eosinophils are much more involved as effector cells in allergy than circulating basophils. Interestingly, basophil numbers change rarely in peripheral blood during an atopic response, while we might yet observe an increase in eosinophils and modification in the biology of mast cells in the tissue during an hypersensitivity response. Furthermore, the fact that basophils are very scanty in numbers suggests that they should mainly serve as regulatory cells in immunity, rather than effector leukocytes, as still believed by the majority of physicians. In this review we will try to describe and elucidate the possible role of these cells, known as "innate IL4-producing cells" in the immune regulation of allergy and their function in allergen immunotherapy.
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[
"After approximately 130 years since their discovery as rare granulocytes that circulate in blood, basophils are just now gaining respect as significant contributors in the pathogenesis underlying allergic inflammation and disease. While long known for secreting preformed and newly synthesized mediators and for selectively infiltrating tissue during immunoglobulin E (IgE)-mediated inflammation, their role has largely been viewed as redundant to that of tissue mast cells in functioning as effector cells. This line of thought has persisted even though it has been known in humans for approximately 20 years that basophils additionally produce relatively large quantities of cytokines, e.g. interleukin-4 (IL-4)/IL-13, that are central for the manifestations of allergic disease. Studies using novel IL-4 reporter mice have significantly added to the in vivo importance of basophils as IL-4 producing cells, with recent findings indicating that these cells also function as antigen-presenting cells essential in initiating T-helper 2 responses. If confirmed and translated to humans, these provocative findings will give new meaning to the role basophils have in allergic disease, and in immunology overall.",
"Mast cells and basophilic granulocytes have recently been recognized as potent immunomodulatory cells. Whereas these cells originally were described as potent cells that release their pro-inflammatory contents (i.e. histamine) unconstrained after activation, nowadays this process is considered to be much more subtle. Especially, via the release of pro- and anti-inflammatory cytokines basophils and mast cells now can steer an immune response. Recently, it has become evident that at least in murine models basophils are crucial for the initial induction of a Th2 response in immunologically naive mouse.",
"Basophils have been recognized as important inducers of T helper type 2 (Th2) responses. Using the colitis model of adoptive transfer of CD4(+) CD62L(+) T cells into lymphopenic hosts, we have analyzed how basophils regulate T-cell responses and modulate disease activity. Transferred T cells rapidly proliferate, produce large amounts of interleukin (IL)-3, and expand the number of basophils in an IL-3-dependent manner. Depletion of basophils with two different antibodies substantially upregulated Th1 cytokines in transferred T cells at day 8. Increased Th1 cytokine expression persisted until the end of the experiment when basophil-depleted mice showed exacerbation of colitis with more severe loss of weight, histological damage, colonic leukocyte infiltration, and expression of pro-inflammatory cytokines. In vitro, we show that basophil-derived IL-4 and IL-6 downregulates expression of interferon-γ, IL-2, and tumor necrosis factor in T cells. These data show a beneficial role of basophils in a T-cell driven model of autoimmunity.",
"Both metazoan parasites and simple protein allergens induce T helper type 2 (TH2) immune responses, but the mechanisms by which the innate immune system senses these stimuli are unknown. In addition, the cellular source of cytokines that control TH2 differentiation in vivo has not been defined. Here we showed that basophils were activated and recruited to the draining lymph nodes specifically in response to TH2-inducing allergen challenge. Furthermore, we demonstrate that the basophil was the accessory cell type required for TH2 induction in response to protease allergens. Finally, we show that basophils were directly activated by protease allergens and produced TH2-inducing cytokines, including interleukin 4 and thymic stromal lymphopoietin, which are involved in TH2 differentiation in vivo.",
"Basophils belong to a myeloid cell population that has been ignored for more than a century, mainly because of its paucity, its lack of specific markers, and the absence of experimental models. Given that in mice, even the mere existence of basophils was contested, they were alluded to as \"histamine-producing cells\" or \"non-T non-B cells\" in initial studies. It is now widely acknowledged that basophils respond to various IgE-dependent or -independent stimuli, and are engaged in a complex cross talk with a number of immunocompetent cells (T or B lymphocytes, macrophages, dendritic cells, endothelial cells…). Indeed, on the one hand they are critically involved during the onset, the effector phase and exacerbation of T(H)2 responses through their capacity to generate large amounts of cytokines with pro-T(H)2 functions (IL-4, IL-13 TSLP, IL-25), on the other hand, they contribute to immunoglobulin synthesis and class switching, angiogenesis, autoimmunity, tumor immunity and hematopoiesis by producing cytokines such as IL-6, VEGF, GM-CSF and IL-3. Finally, it has been established that they can present antigens to CD4+ or CD8+ T cells in an MHC class II- or class I-dependent manner, respectively. Taken together, these activities confer important immunoregulatory functions upon basophils, both in innate and adaptive immunity.",
"Changes of basophil reactivity to housedust extract and anti-IgE during immunotherapy was examined in thirteen patients with bronchial asthma sensitive to housedust. (i) A significant decrease in the morphological reactivity of basophils to housedust extract was observed 6 months after the beginning of immunotherapy with the antigen, and a significant decrease after 12 and 18 months' therapy, accompanied with the decrease of histamine release from the cells. The percent reactive basophils to the antigen decreased from 59.2 +/- 2.9% before the therapy to 40.0 +/- 1.8% after 18 months' immunotherapy. (ii) A decrease in the morphological reactivity of basophils to anti-IgE was also shown during immunotherapy. The basophil reactivity to anti-IgE decreased significantly at the late stage (18 months) of immunotherapy. (iii) A significant reduction of specific IgE antibody to housedust was observed 12 and 18 months after the beginning of immunotherapy. It was suggested from these results that immunotherapy causes some changes on the surface of basophils and decreased reactivity of the cells, and that a decrease of reactive basophils to anti-IgE in the process of immunotherapy might be due to a decrease in number of IgE receptors essentially or functionally."
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Stress and Borderline Personality Disorder
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Borderline personality disorder (BPD) is a severe and frequent disorder characterized by a pervasive pattern of instability affecting impulse control, emotional regulation, cognitive processing, self-image and interpersonal relationships. Patients' personal histories are often marked by stressful or traumatic experiences, either unique or repeated. Moreover, while clinical signs of the disorder include both chronic and acute features, acute features are mostly triggered by acute stressful situations. Such features include transient cognitive distortion, intense anger, uncontrollable impulsivity, and self-harm behavior - including suicide - and contribute to the burden of the disease. In this paper, we review the various aspects (epidemiological, clinical, and physiological) contributing to the relationship between BDP and stress. In particular, we explore the statistical association between stress exposure and the emergence of BPD while taking into account other psychopathologies, such as post-traumatic stress disorder. Then, the different aspects of stress responses (namely, the phenomenological, behavioral, hormonal, neuro-vegetative and neural responses) are reviewed in BPD patients. Pathophysiological hypotheses are formulated to explain the differences in responses between BPD patients and healthy subjects and their relation to BPD symptoms. Although the pathogenesis remains uncertain, our conclusions seem to reflect a specific biological and neural pattern of altered stress perception and regulation in BPD.
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"The purpose of this study was to assess a full range of pathological childhood experiences reported by patients with criteria-defined borderline personality disorder and comparison patients with other personality disorders. The pathological childhood experiences reported by 467 inpatients with personality disorders were assessed by interviewers who used a semistructured research interview and were blind to clinical diagnosis. Of the 358 patients with borderline personality disorder, 91% reported having been abused, and 92% reported having been neglected, before the age of 18. The borderline patients were significantly more likely than the 109 patients with other personality disorders to report having been emotionally and physically abused by a caretaker and sexually abused by a noncaretaker. They were also significantly more likely to report having a caretaker withdraw from them emotionally, treat them inconsistently, deny their thoughts and feelings, place them in the role of a parent, and fail to provide them with needed protection. The borderline patients with a childhood history of sexual abuse were significantly more likely than those without such a history to report having experienced all but one of the types of abuse and neglect studied. When all significant risk factors were considered together, four were found to be significant predictors of a borderline diagnosis: female gender, sexual abuse by a male noncaretaker, emotional denial by a male caretaker, and inconsistent treatment by a female caretaker. The results suggest that sexual abuse is neither necessary nor sufficient for the development of borderline personality disorder and that other childhood experiences, particularly neglect by caretakers of both genders, represent significant risk factors.",
"Borderline personality disorder (BPD) is a severe and often debilitating psychiatric disorder that begins during adolescence. Core features of BPD are affective dysregulation, dysfunctional self-concepts, and difficulties in social interactive domains. A widely accepted marker for severe emotion dysregulation in adult BPD is decreased pain sensitivity. Until now it is unclear whether this characteristic feature of BPD is already present during adolescence. Thus, this study aims to investigate pain sensitivity in adolescent patients meeting DSM-IV criteria for BPD. 20 female adolescent patients with BPD (mean age 16.4 years) and 20 healthy age-matched control participants were investigated. Detection and pain thresholds for thermal stimuli were assessed on both hands. Furthermore, self-rating instruments were used to assess overall psychopathology, dissociation, and depression. We found significantly higher pain thresholds in patients with BPD than in healthy controls. Patients with BPD had higher intensities of depression, overall psychopathology, and dissociative symptoms, but there was no correlation between pain sensitivity and any of these measures of psychopathology. These findings are in line with previous findings in adult BPD patients concerning lower pain sensitivity as compared to healthy controls. This provides support for the idea that disturbed pain processing is not only a consequence of chronic BPD but is already present in early stages of BPD.",
"Subjects with borderline personality disorder (N = 21) or borderline traits (N = 11) and nonborderline subjects with closely related diagnoses (N = 23) were interviewed in depth regarding experiences of major childhood trauma. Significantly more borderline subjects (81%) gave histories of such trauma, including physical abuse (71%), sexual abuse (68%), and witnessing serious domestic violence (62%); abuse histories were less common in those with borderline traits and least common in the subjects with no borderline diagnosis. These results demonstrate a strong association between a diagnosis of borderline personality disorder and a history of abuse in childhood.",
"Difficulties with emotions are common across mood and anxiety disorders. Dialectical behavior therapy skills training (DBT-ST) reduces emotion dysregulation in borderline personality disorder (BPD). Preliminary evidence suggests that use of DBT skills mediates changes seen in BPD treatments. Therefore, we assessed DBT-ST as a stand-alone, transdiagnostic treatment for emotion dysregulation and DBT skills use as a mediator of outcome. Forty-four anxious and/or depressed, non-BPD adults with high emotion dysregulation were randomized to 16 weeks of either DBT-ST or an activities-based support group (ASG). Participants completed measures of emotion dysregulation, DBT skills use, and psychopathology every 2 months through 2 months posttreatment. Longitudinal analyses indicated that DBT-ST was superior to ASG in decreasing emotion dysregulation (d = 1.86), increasing skills use (d = 1.02), and decreasing anxiety (d = 1.37) but not depression (d = 0.73). Skills use mediated these differential changes. Participants found DBT-ST acceptable. Thirty-two percent of DBT-ST and 59% of ASG participants dropped treatment. Fifty-nine percent of DBT-ST and 50% of ASG participants complied with the research protocol of avoiding ancillary psychotherapy and/or medication changes. In summary, DBT-ST is a promising treatment for emotion dysregulation for depressed and anxious transdiagnostic adults, although more assessment of feasibility is needed.",
"Experiences of early life stress, increased psychological arousal and the body's physiologic stress response seem to play an important role in the pathogenesis and maintenance of borderline personality disorder (BPD). In the present study, we investigated alterations in grey matter of central stress-regulating structures in female patients with BPD. We examined T1-weighted structural magnetic resonance imaging scans of unmedicated, right-handed female patients with BPD (according to DSM-IV criteria) and healthy controls matched for age, intelligence and education using fully automated DARTEL voxel-based morphometry. Our regions of interest analyses included the hippocampus, amygdala, anterior cingulate cortex (ACC) and hypothalamus. We enrolled 30 patients and 33 controls in our study. The grey matter of patients with BPD was reduced in the hippocampus, but increased in the hypothalamus compared with healthy participants. Hypothalamic volume correlated positively with the history of traumatization in patients with BPD. No significant alterations were found in the amygdala and ACC. This study is limited by the lack of measures of corticotropin-releasing hormone, adrenocorticotropic hormone and cortisol levels. Furthermore, moderate sample size and comorbid disorders need to be considered. Our findings provide new evidence for grey matter alterations in the hypothalamus and replicate previously reported decrements in hippocampal volume in patients with BPD. Understanding the role of the hypothalamus and other central stress-regulating structures could help us to further understand the neurobiological underpinnings of this complex disorder.",
"Gaining new insights into the anatomy of the human hypothalamus is crucial for the development of new treatment strategies involving functional stereotactic neurosurgery. Here, using anatomical comparisons between histology and magnetic resonance images of the human hypothalamus in the coronal plane, we show that discrete gray and white hypothalamic structures are consistently identifiable by MRI. Macroscopic and microscopic images were used to precisely annotate the MRI sequences realized in the coronal plane in twenty healthy volunteers. MRI was performed on a 1.5 T scanner, using a protocol including T1-weighted 3D fast field echo, T1-weighted inversion-recovery, turbo spin echo and T2-weighted 2D fast field echo imaging. For each gray matter structure as well as for white matter bundles, the different MRI sequences were analyzed in comparison to each other. The anterior commissure and the fornix were often identifiable, while the mammillothalamic tract was more difficult to spot. Qualitative analyses showed that MRI could also highlight finer structures such as the paraventricular nucleus, the ventromedial nucleus of the hypothalamus and the infundibular (arcuate) nucleus, brain nuclei that play key roles in the regulation of food intake and energy homeostasis. The posterior hypothalamic area, a target for deep brain stimulation in the treatment of cluster headaches, was readily identified, as was the lateral hypothalamic area, which similar to the aforementioned hypothalamic nuclei, could be a putative target for deep brain stimulation in the treatment of obesity. Finally, each of the identified structures was mapped to Montreal Neurological Institute (MNI) space.",
"Patients with borderline personality disorder are characterized by emotional hyperarousal with increased stress levels, anger proneness, and hostile, impulsive behaviors. They tend to ascribe anger to ambiguous facial expressions and exhibit enhanced and prolonged reactions in response to threatening social cues, associated with enhanced and prolonged amygdala responses. Because the intranasal administration of the neuropeptide oxytocin has been shown to improve facial recognition and to shift attention away from negative social information, the authors investigated whether borderline patients would benefit from oxytocin administration. In a randomized placebo-controlled double-blind group design, 40 nonmedicated, adult female patients with a current DSM-IV diagnosis of borderline personality disorder (two patients were excluded based on hormonal analyses) and 41 healthy women, matched on age, education, and IQ, took part in an emotion classification task 45 minutes after intranasal administration of 26 IU of oxytocin or placebo. Dependent variables were latencies and number or initial reflexive eye movements measured by eye tracking, manual response latencies, and blood-oxygen-level-dependent responses of the amygdala to angry and fearful compared with happy facial expressions. Borderline patients exhibited more and faster initial fixation changes to the eyes of angry faces combined with increased amygdala activation in response to angry faces compared with the control group. These abnormal behavioral and neural patterns were normalized after oxytocin administration. Borderline patients exhibit a hypersensitivity to social threat in early, reflexive stages of information processing. Oxytocin may decrease social threat hypersensitivity and thus reduce anger and aggressive behavior in borderline personality disorder or other psychiatric disorders with enhanced threat-driven reactive aggression.",
"This article critically reviews the problems concerning the relationship between traumatic events in childhood and personality disorders in adulthood. Attributing adult psychopathology primarily to environmental factors is problematic. Personality traits are heritable. Children are resilient to the long-term effects of trauma. All studies of trauma in personality disordered patients suffer from retrospective designs. Only a minority of patients with severe personality disorders report severe childhood trauma. The effects of trauma in the personality disorders can be better understood in the context of gene-environment interactions.",
"The authors examined whether patients with comorbid borderline personality disorder and posttraumatic stress disorder (PTSD) have a more severe clinical profile than patients with either disorder without the other. Outpatients with borderline personality disorder without PTSD (N=101), PTSD without borderline personality disorder (N=121), comorbid borderline personality disorder and PTSD (N=48), and major depression without PTSD or borderline personality disorder (N=469) were assessed with structured interviews for psychiatric disorders and for degree of impairment. Outpatients with diagnoses of comorbid borderline personality disorder and PTSD were not significantly different from outpatients with borderline personality disorder without PTSD, PTSD without borderline personality disorder, or major depression without PTSD or borderline personality disorder in severity of PTSD-related symptoms, borderline-related traits, or impairment. The additional diagnosis of PTSD or borderline personality disorder does little to augment the pathology or dysfunction of patients who have either disorder without the other.",
"Childhood maltreatment represents a strong risk factor for the development of depression and posttraumatic stress disorder (PTSD) in later life. In the present study, we investigated the neurobiological underpinnings of this association. Since both depression and PTSD have been associated with increased amygdala responsiveness to negative stimuli as well as reduced hippocampal gray matter volume, we speculated that childhood maltreatment results in similar functional and structural alterations in previously maltreated but healthy adults. One hundred forty-eight healthy subjects were enrolled via public notices and newspaper announcements and were carefully screened for psychiatric disorders. Amygdala responsiveness was measured by means of functional magnetic resonance imaging and an emotional face-matching paradigm particularly designed to activate the amygdala in response to threat-related faces. Voxel-based morphometry was used to study morphological alterations. Childhood maltreatment was assessed by the 25-item Childhood Trauma Questionnaire (CTQ). We observed a strong association of CTQ scores with amygdala responsiveness to threat-related facial expressions. The morphometric analysis yielded reduced gray matter volumes in the hippocampus, insula, orbitofrontal cortex, anterior cingulate gyrus, and caudate in subjects with high CTQ scores. Both of these associations were not influenced by trait anxiety, depression level, age, intelligence, education, or more recent stressful life events. Childhood maltreatment is associated with remarkable functional and structural changes even decades later in adulthood. These changes strongly resemble findings described in depression and PTSD. Therefore, the present results might suggest that limbic hyperresponsiveness and reduced hippocampal volumes could be mediators between the experiences of adversities during childhood and the development of emotional disorders."
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Igf2 and H19 Misexpression in Beckwith Wiedemann Syndrome
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Imprinted genes occur in discrete clusters that are coordinately regulated by shared DNA elements called Imprinting Control Regions. H19 and Igf2 are linked imprinted genes that play critical roles in development. Loss of imprinting (LOI) at the IGF2/H19 locus on the maternal chromosome is associated with the developmental disorder Beckwith Wiedemann Syndrome (BWS) and with several cancers. Here we use comprehensive genetic and genomic analyses to follow muscle development in a mouse model of BWS to dissect the separate and shared roles for misexpression of Igf2 and H19 in the disease phenotype. We show that LOI results in defects in muscle differentiation and hypertrophy and identify primary downstream targets: Igf2 overexpression results in over-activation of MAPK signaling while loss of H19 lncRNA prevents normal down regulation of p53 activity and therefore results in reduced AKT/mTOR signaling. Moreover, we demonstrate instances where H19 and Igf2 misexpression work separately, cooperatively, and antagonistically to establish the developmental phenotype. This study thus identifies new biochemical roles for the H19 lncRNA and underscores that LOI phenotypes are multigenic so that complex interactions will contribute to disease outcomes.
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"Taxol is an anticancer agent of natural origin with significant activity against a number of human cancers including ovarian and breast carcinomas. Its cytotoxic activity has been attributed to its ability to stabilize microtubules and to promote microtubule assembly. Recently it has become clearer that Taxol has additional activities including effects in cell signaling and gene expression. We have shown previously that Taxol activates ERK 1/2 MAP-kinases and results in the formation of GRB2/SHC complexes in murine macrophage-like RAW 267.4 cells. Here we demonstrate that Taxol activates ERK 1/2 and p38 MAP-kinases in human ovarian carcinoma cells with distinct kinetics. Activation of ERK1/2 has been observed at low concentrations of Taxol (1-100 nM) within 0.5-6 h, whereas longer exposure(24 h) to nanomolar concentrations of Taxol resulted in an abrogation of the ERK1/2 phosphorylation/activation. Higher concentrations (1-10 microM) resulted in a sharp inhibition of ERK1/2 activity. p38 kinase was activated by high concentrations (1-10 microM) of Taxol within 2 h and remained active for more than 24 h. The kinetic studies showed that these effects of Taxol coincided with an inhibition of proliferation, and the onset of apoptosis. The appearance of the fragmented chromatin visualized by DAPI staining, and DNA fragments seen on an agarose gel, coincided with the decrease in ERK1/2 activation and concomitant increase of the level of active p38 MAPK. The inhibitor PD98059 abrogated ERK 1/2 activation and increased the cytotoxic effect of Taxol. An inhibitor of p38 kinase, SB203580, protected the cells partially from Taxol and, unexpectedly, activated ERK 1/2 kinases. We conclude that the alternative use of ERK1/2 and p38 MAP-kinase pathways may be necessary for the transition from proliferation state to Taxol-induced apoptosisin human ovarian carcinoma cells.",
"Previous studies on skeletal muscle differentiation showed that myogenesis is regulated by extracellular signal-regulated kinases (ERK-1/-2) and p38 mitogen activated kinase (MAPK) pathways. Present study shows that c-Jun NH2-terminal protein kinase (JNK) activities were up regulated during skeletal muscle differentiation in rat skeletal muscle L6E9 cells, as determined by Western immunoblot of differentiating cells probed with anti-phospho-JNK antibody. Inhibition of JNK activities by JNK inhibitor II drastically inhibited differentiation as determined by decreased myosin, myogenin expression and creatine kinase activity. The inhibition of the differentiation was regulated by apoptosis as determined by the detection of poly(ADP-ribose) polymerase (PARP) cleavage, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positive cells when JNK activities were inhibited. Apoptosis was accompanied by marked expression and activation of c-Jun and p53 transcription factors. Taken together, our results indicate that basal JNK activities are essential for regulating skeletal muscle differentiation, and inhibition of JNK activation affects myogenesis by apoptosis dependent on c-Jun and p53 transcription factors.",
"Differentiation therapy for neoplastic diseases has potential for supplementing existing treatment modalities but its implementation has been slow. One of the reasons is the lack of full understanding of the complexities of cellular pathways through which signals for differentiation lead to cell maturation. This was addressed in this study using HL60 cells, a well-established model of differentiation of neoplastic cells. SB 203580 and SB 202190, specific inhibitors of a signaling protein p38 MAP kinase, were found to markedly accelerate monocytic differentiation of HL60 cells induced by low concentrations of 1,25-dihydroxyvitamin D(3) (1,25D(3)). Surprisingly, inhibition of p38 activity resulted in sustained enhancement of p38 phosphorylation and of its in vitro activity in the absence of the inhibitor, indicating up-regulation of the upstream components of the p38 pathway. In addition, SB 203580 or SB 202190 treatment of HL60 cells resulted in a prolonged activation of the JNK and, to a lesser extent, the ERK pathways. The data are consistent with the hypothesis that in HL60 cells an interruption of a negative feedback loop from a p38 target activates a common regulator of multiple MAPK pathways. The possibility also exists that JNK and/or ERK pathways amplify a differentiation signal provided by 1,25D(3).",
"Skeletal muscle hypertrophy is defined as an increase in muscle mass, which in the adult animal comes as a result of an increase in the size, as opposed to the number, of pre-existing skeletal muscle fibers. The protein growth factor insulin-like growth factor 1 (IGF-1) has been demonstrated to be sufficient to induce skeletal muscle hypertrophy. Over the past few years, signaling pathways which are activated by IGF-1, and which are responsible for regulating protein synthesis pathways, have been defined. More recently, it has been show that IGF-1 can also block the transcriptional upregulation of key mediators of skeletal muscle atrophy, the ubiquitin-ligases MuRF1 and MAFbx (also called Atrogin-1). Further, it has been demonstrated recently that activation of the NF-kappaB transcription pathway, activated by cachectic factors such as TNFalpha, is sufficient to induce skeletal muscle atrophy, and this atrophy occurs in part via NF-kappaB-mediated upregulation of MuRF1. Further work has demonstrated a trigger for MAFbx expression upon treatment with TNFalpha--the p38 MAPK pathway. This review will focus on the recent progress in the understanding of molecular signalling, which governs skeletal muscle atrophy and hypertrophy, and the known instances of cross-regulation between the two systems.",
"The role of polypeptide growth factors in promoting muscle differentiation is uncharacterized. We have used a fusing skeletal muscle cell line, C2, to examine the endogenous expression of one peptide, insulin-like growth factor II (IGF-II), and its receptor during differentiation. The synthesis of IGF-II is low during proliferation of myoblasts; IGF-II mRNA can be detected only through use of a highly sensitive solution-hybridization assay. Competition binding studies reveal that the IGF-II receptor is similarly nonabundant in myoblasts. During differentiation IGF-II mRNA rises rapidly. A nearly 4-fold increase is seen within 16 hr of onset of the differentiation process, and levels are 25 times higher than those in myoblasts by 96 hr, when myotubes have formed and muscle-specific alpha-actin mRNAs are synthesized. IGF-II accumulates in conditioned culture medium with similar kinetics. The expression of IGF-II receptors on the cell surface increases almost 6-fold 24 hr after the onset of differentiation and remains high. These studies suggest that IGF-II and its receptor are coordinately regulated during myogenic differentiation in C2 cells and that IGF-II may be an autocrine factor for skeletal muscle.",
"Developmentally regulated transcription often depends on physical interactions between distal enhancers and their cognate promoters. Recent genomic analyses suggest that promoter-promoter interactions might play a similarly critical role in organizing the genome and establishing cell-type-specific gene expression. The Igf2/H19 locus has been a valuable model for clarifying the role of long-range interactions between cis-regulatory elements. Imprinted expression of the linked, reciprocally imprinted genes is explained by parent-of-origin-specific chromosomal loop structures between the paternal Igf2 or maternal H19 promoters and their shared tissue-specific enhancer elements. Here, we further analyze these loop structures for their composition and their impact on expression of the linked long non-coding RNA, Nctc1. We show that Nctc1 is co-regulated with Igf2 and H19 and physically interacts with the shared muscle enhancer. In fact, all three co-regulated genes have the potential to interact not only with the shared enhancer but also with each other via their enhancer interactions. Furthermore, developmental and genetic analyses indicate functional significance for these promoter-promoter interactions. Altogether, we present a novel mechanism to explain developmental specific imprinting of Nctc1 and provide new information about enhancer mechanisms and about the role of chromatin domains in establishing gene expression patterns.",
"The imprinted oncofetal long non-coding RNA (lncRNA) H19 is expressed in the embryo, down-regulated at birth and then reappears in tumors. Its role in tumor initiation and progression has long been a subject of controversy, although accumulating data suggest that H19 is one of the major genes in cancer. It is actively involved in all stages of tumorigenesis and is expressed in almost every human cancer. In this review we delineate the various functions of H19 during the different stages in the complex process of tumor progression. H19 up-regulation allows cells to enter a \"selfish\" survival mode in response to stress conditions, such as destabilization of the genome and hypoxia, by accelerating their proliferation rate and increasing overall cellular resistance to stress. This response is tightly correlated with nullification, dysfunction or significant down-regulation of the master tumor suppressor gene P53. The growing evidence of H19's involvement in both proliferation and differentiation processes, together with its involvement in epithelial to mesenchymal transition (EMT) and also mesenchymal to epithelial transition (MET), has led us to conclude that some of the recent disputes and discrepancies arising from current research findings can be resolved from a viewpoint supporting the oncogenic properties of H19. According to a holistic approach, the versatile, seemingly contradictory functions of H19 are essential to, and differentially harnessed by, the tumor cell depending on its context within the process of tumor progression.",
"Igf2 and H19 exhibit parent-of-origin-specific monoallelic expression. H19 is expressed from the maternal chromosome and Igf2 from the paternal. The two genes share enhancer elements and monoallelic expression of both genes is dependent on cis-acting sequences upstream of the H19 promoter. In this work we examine the mechanisms by which this region silences the maternal Igf2 allele and we demonstrate that deletion of this region can result in high levels of activation of both H19 and Igf2 from a single chromosome. Moreover, by inserting this cis element between a promoter and its enhancer at a heterologous position, we demonstrate that the sequences carry both insulator activity and the ability to be stably imprinted. We also characterize the insulator in vitro and show that it is neither enhancer nor promoter specific.",
"The differentiation of muscle cells is controlled by the MyoD family of transcription factors. This family is regulated by extracellular growth factors that transmit largely unknown signals into the cells. Here we show that the activity of extracellular signal-regulated protein kinase (ERK), a kinase that is part of the mitogen-activated protein kinase (MAPK) cascade, is low in myoblasts and is induced with the onset of terminal differentiation of C2 cells. ERK activity is also induced in fibroblasts that were modified to express MyoD, but not in the parental fibroblast cells. Thus, ERK induction is an intrinsic property of muscle cells. A specific MAPK kinase inhibitor (PD098059) that was added to C2 cells partially inhibited the fusion of myoblasts to multinucleated myotubes without affecting the expression of muscle-specific markers. This inhibitor blocked the induction of MyoD expression that normally takes place during terminal differentiation. Two lines of evidence suggest that the MAPK cascade induces the activity of MyoD: 1) the expression of constitutively activated forms of MEK1 or Raf1 enhanced the transcriptional activity of MyoD in 10T1/2 fibroblasts; and 2) the addition of PD098059 to fibroblast cells expressing a conditional MyoD-estrogen fusion protein significantly inhibited the expression of MyoD-responsive genes. Our results indicate that the MAPK pathway is activated in differentiating muscle cells and that it positively regulates the expression and activity of MyoD protein.",
"The human beta-globin genes are regulated by the locus control region (LCR), an element composed of multiple DNase I-hypersensitive sites (HS sites) located 5' to the genes. Various functional studies indicate that the LCR confers high-level, position-independent, and copy number-dependent expression to linked globin genes in transgenic mice. However, the structural basis for LCR function is unknown. Here we show that LCR HS sites can be reconstituted in an erythroid cell-specific manner on chromatin-assembled LCR templates in vitro. Surprisingly, HS2 and HS3 are also formed with erythroid proteins in the absence of chromatin assembly, indicating that sensitivity to nucleases is not simply a consequence of nucleosome reorganization. The generation of LCR HS sites in the absence of chromatin assembly leads to the formation of S1- and KMnO(4)-sensitive regions in HS2 and HS3. These sites are also sensitive to S1 nuclease in erythroid cells in vivo, suggesting a distorted DNA structure in the LCR core enhancer elements. Finally, we show that RNA polymerase II initiates transcription in the HS2 and HS3 core enhancer regions in vitro. Transcription in both HS2 and HS3 proceeds in a unidirectional manner. Taken together, the data suggest that erythroid proteins interact with the core enhancer elements, distort the DNA structure, and recruit polymerase II transcription complexes. These results further our understanding of the structural basis for LCR function and provide an explanation for why the LCR core regions are so extremely sensitive to nucleases in erythroid cells."
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Effect of sodium 2-mercaptoethane sulfonate on durability of prophylaxis in implant-associated surgical pockets
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Implant-associated surgical-site infections can have significant clinical consequences. Previously we reported a method for prophylactically disinfecting implant surfaces in surgical pockets, where an antibiotic solution containing minocycline (M) and rifampin (R) was applied as a solid film in a crosslinked biopolymer matrix that partially liquefied in situ to provide extended prophylaxis. Here we studied the effect of adding sodium 2-mercaptoethane sulfonate (MeSNA) on durability of prophylaxis in an
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"The use of central venous catheters impregnated with either minocycline and rifampin or chlorhexidine and silver sulfadiazine reduces the rates of catheter colonization and catheter-related bloodstream infection as compared with the use of unimpregnated catheters. We compared the rates of catheter colonization and catheter-related bloodstream infection associated with these two kinds of antiinfective catheters. We conducted a prospective, randomized clinical trial in 12 university-affiliated hospitals. High-risk adult patients in whom central venous catheters were expected to remain in place for three or more days were randomly assigned to undergo insertion of polyurethane, triple-lumen catheters impregnated with either minocycline and rifampin (on both the luminal and external surfaces) or chlorhexidine and silver sulfadiazine (on only the external surface). After their removal, the tips and subcutaneous segments of the catheters were cultured by both the roll-plate and the sonication methods. Peripheral-blood cultures were obtained if clinically indicated. Of 865 catheters inserted, 738 (85 percent) produced culture results that could be evaluated. The clinical characteristics of the patients and the risk factors for infection were similar in the two groups. Catheters impregnated with minocycline and rifampin were 1/3 as likely to be colonized as catheters impregnated with chlorhexidine and silver sulfadiazine (28 of 356 catheters [7.9 percent] vs. 87 of 382 [22.8 percent], P<0.001), and catheter-related bloodstream infection was 1/12 as likely in catheters impregnated with minocycline and rifampin (1 of 356 [0.3 percent], vs. 13 of 382 [3.4 percent] for those impregnated with chlorhexidine and silver sulfadiazine; P<0.002). The use of central venous catheters impregnated with minocycline and rifampin is associated with a lower rate of infection than the use of catheters impregnated with chlorhexidine and silver sulfadiazine.",
"The incidence of infection following breast reconstruction with expanders and implants ranges from 1 to 24 percent. Numerous factors associated with infection have been described; however, a one-variable at time setting and multifactorial analysis have not been performed. The purpose of this study was to analyze a set of factors that may predispose women to infection of the expander or implant. Between 1997 and 2000, a total of 168 implant reconstructions were performed in 130 women at a single institution. The mean age for all women was 48.2 years (range, 25 to 77 years). The factors that were analyzed included axillary lymph node dissection, chemotherapy, radiation therapy, tumor stage, timing of implant insertion, number of sides (unilateral versus bilateral), tobacco use, and presence or absence of diabetes mellitus. Statistical analysis was performed with stepwise logistic regression. Mean time to follow-up for all patients was 29 months (range, 12 to 47 months). Infectious complications occurred in 10 women (7.7 percent) and in 10 expanders or implants (5.9 percent). Infected implants were removed an average of 116 days following insertion (range, 14 to 333 days). Cultured bacteria included Staphylococcus aureus and Serratia marcescens. A significant association (p < 0.04) was detected between implant infection and radiation therapy. The chance for implant infection was 4.88 times greater for implants that were exposed to radiation therapy compared with those that were not. In addition, there was suggestive (p < 0.09) evidence that the chance of implant infection following lymph node dissection was 6.29 times higher than when no lymph nodes were removed. No significant association between implant infection and age, diabetes, tobacco use, tumor stage, timing of implant insertion, or chemotherapy was found.",
"To evaluate the efficacy of long-term nontunneled silicone catheters impregnated with minocycline and rifampin (M-R) in reducing catheter-related bloodstream infections. This prospective, randomized, double-blind clinical trial was conducted at M.D. Anderson Cancer Center, a tertiary care hospital in Houston, TX. All patients in the trial had a malignancy. Between September 1999 and May 2002, 356 assessable catheters were used: 182 M-R and 174 nonimpregnated. The patients' characteristics were comparable between the two study groups. The mean (+/- standard deviation) duration of catheterization with M-R catheters was comparable to that of nonimpregnated catheters (66.21 +/- 30.88 v 63.01 +/- 30.80 days). A total of 17 catheter-related bloodstream infections occurred during the course of the study. Three were associated with the use of M-R catheters and 14 were associated with the nonimpregnated catheters, with a rate of catheter-related bloodstream infection of 0.25 and 1.28/1,000 catheter-days, respectively (P = .003). Gram-positive cocci accounted for the majority of the organisms causing the infections. There were no allergic reactions associated with M-R catheters. Long-term nontunneled central venous catheters impregnated with minocycline and rifampin are efficacious and safe in reducing catheter-related bloodstream infections in cancer patients.",
"Dye exclusion tests are used to determine the number of live and dead cells. These assays are based on the principle that intact plasma membranes in live cells exclude specific dyes, whereas dead cells do not. Although widely used, the trypan blue (TB) exclusion assay has limitations. The dye can be incorporated by live cells after a short exposure time, and personal reliability, related to the expertise of the analyst, can affect the results. We propose an alternative assay for evaluating cell viability that combines the TB exclusion test and the high sensitivity of the flow cytometry technique. Previous studies have demonstrated the ability of TB to emit fluorescence when complexed with proteins. According to our results, TB/bovine serum albumin and TB/cytoplasmic protein complexes emit fluorescence at 660 nm, which is detectable by flow cytometry using a 650-nm low-pass band filter. TB at 0.002% (w/v) was defined as the optimum concentration for distinguishing unstained living cells from fluorescent dead cells, and fluorescence emission was stable for 30 min after cell treatment. Although previous studies have shown that TB promotes green fluorescence quenching, TB at 0.002% did not interfere with green fluorescence in human live T-cells stained with anti-CD3/fluorescein isothiocyanate (FITC) monoclonal antibody. We observed a high correlation between the percentage of propidium iodide+CD3/FITC+ and TB+CD3/FITC+ cells, as well as similar double-stained cell profiles in flow cytometry dot-plot graphs. Taken together, the results indicate that a TB exclusion assay by flow cytometry can be employed as an alternative tool for quick and reliable cell viability analysis.",
"The protocol described in this appendix allows for light microscopic quantitation of cell viability. Cells are suspended in PBS containing trypan blue and then examined to determine the percentage of cells that have clear cytoplasm (viable cells) versus cells that have blue cytoplasm (nonviable cells).",
"We show here the identity of Alamar Blue as resazurin. The 'resazurin reduction test' has been used for about 50 years to monitor bacterial and yeast contamination of milk, and also for assessing semen quality. Resazurin (blue and nonfluorescent) is reduced to resorufin (pink and highly fluorescent) which is further reduced to hydroresorufin (uncoloured and nonfluorescent). It is still not known how this reduction occurs, intracellularly via enzyme activity or in the medium as a chemical reaction, although the reduced fluorescent form of Alamar Blue was found in the cytoplasm and of living cells nucleus of dead cells. Recently, the dye has gained popularity as a very simple and versatile way of measuring cell proliferation and cytotoxicity. This dye presents numerous advantages over other cytotoxicity or proliferation tests but we observed several drawbacks to the routine use of Alamar Blue. Tests with several toxicants in different cell lines and rat primary hepatocytes have shown accumulation of the fluorescent product of Alamar Blue in the medium which could lead to an overestimation of cell population. Also, the extensive reduction of Alamar Blue by metabolically active cells led to a final nonfluorescent product, and hence an underestimation of cellular activity.",
"The cell viability test is an essential tool in any laboratory, performing cell-based studies and clinical laboratory tests. The trypan blue exclusion method is the most popular assay for its simple concept among various diagnostic tools. However, several disadvantages include time-consuming and labor-intensive steps with low precision. In this study, we evaluated a new technique for the automatic cell viability measurement with microscopic cell counter and microchip. Upon blood draw from 11 healthy volunteers, Mononuclear cells were separated immediately from the heparinized whole blood, and the viable cells were diluted from 100 to 1%. The cell viability tests were performed simultaneously with following three methods: the conventional manual trypan blue exclusion method; the flow cytometry measurement with propidium iodide stain; and the newly developed microscopic cell counter with microchip. Linearities, precisions, and correlations from three methods were analyzed and compared. The correlations data from the microscopic cell counter were in good agreement with both the conventional trypan blue method (r=0.99, P<0.05) and the flow cytometry (r=0.99, P<0.05), respectively. The precision (2.0-6.2%) and linearity from the microscopic cell counter method with microchip were superior in comparison with the conventional method. The microscopic cell counter with microchip performed well with high precision, linearity, and efficient running time than both the manual trypan blue and the flow cytometry methods.",
"Breast reconstruction surgeries using tissue expanders (TEs) have highly reported infection rates. To decrease this, we developed a method for disinfecting TEs and surgical pockets, where an antimicrobial solution was applied as a solid film at implantation that subsequently liquefied in situ to provide extended prophylaxis. Silicone discs cut from TEs were covered with gelatin-based films containing minocycline (M) and rifampin (R). Discs and films soaked in saline were subsequently challenged with pathogen at days 1, 3, 7, and 10 and quantified for potential biofilm formation. Discs that were not harvested at each specific time points were refreshed with sterile saline. The discs were challenged with clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), and multidrug-resistant Pseudomonas aeruginosa (MDR-PA). Recoveries of adherent organisms from uncovered silicone discs and gelatin-wrapped discs without added antimicrobial agents were >5 × 10(4) CFU/disc for each organism at each time point. Experimental 0.1%M/0.05%R gelatin films completely inhibited all challenge organisms from attaching to the silicone (p < 0.05) at each time point through day 10. Cytotoxicity was assessed by incubating films with HEK-293T human fibroblasts. There were no significant differences in HEK-293T cell survival between controls and any of the antimicrobial films. The in situ liquefying, bioabsorable, antimicrobial wrap prevented biofilm formation by microorganisms on silicone surfaces in vitro with minimal cytotoxicity."
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Effects of maternal high fat diet consumption on hypothalamic gene expression in Sprague Dawley rat offspring
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Maternal consumption of a high fat diet during early development has been shown to impact the formation of hypothalamic neurocircuitry, thereby contributing to imbalances in appetite and energy homeostasis and increasing the risk of obesity in subsequent generations. Early in postnatal life, the neuronal projections responsible for energy homeostasis develop in response to appetite-related peptides such as leptin. To date, no study characterises the genome-wide transcriptional changes that occur in response to exposure to high fat diet during this critical window. We explored the effects of maternal high fat diet consumption on hypothalamic gene expression in Sprague Dawley rat offspring at postnatal day 10. RNA-sequencing enabled discovery of differentially expressed genes between offspring of dams fed a high fat diet and offspring of control diet fed dams. Female high fat diet offspring displayed altered expression of 86 genes (adjusted P-value<0.05), including genes coding for proteins of the extra cellular matrix, particularly Collagen 1a1 (Col1a1), Col1a2, Col3a1, and the imprinted Insulin-like growth factor 2 (Igf2) gene. Male high fat diet offspring showed significant changes in collagen genes (Col1a1 and Col3a1) and significant upregulation of two genes involved in regulation of dopamine availability in the brain, tyrosine hydroxylase (Th) and dopamine reuptake transporter Slc6a3 (also known as Dat1). Transcriptional changes were accompanied by increased body weight, body fat and body length in the high fat diet offspring, as well as altered blood glucose and plasma leptin. Transcriptional changes identified in the hypothalamus of offspring of high fat diet mothers could alter neuronal projection formation during early development leading to abnormalities in the neuronal circuitry controlling appetite in later life, hence priming offspring to the development of obesity.
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"Maternal obesity during pregnancy increases the risk of obesity in the offspring. Obesity, arising from an imbalance of energy intake and expenditure, can be driven by the ingestion of palatable [high fat (HF), high sugar], energy-dense foods. Dopamine and opioid circuitry are neural substrates associated with reward that can affect animals' preference for palatable foods. Using a mouse model, the long-term effect of maternal consumption of a HF diet on dopamine and opioid gene expression within the mesocorticolimbic reward circuitry and hypothalamus of the offspring was investigated. Mice from dams fed a HF diet during pregnancy and lactation showed an increased preference for sucrose and fat. Gene expression, measured using quantitative real-time PCR, revealed a significant approximately 3- to 10-fold up-regulation of dopamine reuptake transporter (DAT) in the ventral tegmental area, nucleus accumbens, and prefrontal cortex and a down-regulation of DAT in the hypothalamus. Additionally, expression of both μ-opioid receptor (MOR) and preproenkephalin (PENK) was increased in nucleus accumbens, prefrontal cortex, and hypothalamus of mice from dams that consumed the HF diet. Epigenetic mechanisms have been associated with long-term programming of gene expression after various in utero insults. We observed global and gene-specific (DAT, MOR, and PENK) promoter DNA hypomethylation in the brains of offspring from dams that consumed the HF diet. These data demonstrate that maternal consumption of a HF diet can change the offsprings' epigenetic marks (DNA hypomethylation) in association with long-term alterations in gene expression (dopamine and opioids) and behavior (preference for palatable foods).",
"Epidemiological studies initially demonstrated that maternal undernutrition leading to low birth weight may predispose for energy balance disorders throughout life. High birth weight due to maternal obesity or diabetes, inappropriate early post-natal nutrition and rapid catch-up growth may also sensitise to increased risk of obesity. As stated by the Developmental Origin of Health and Disease concept, the perinatal perturbation of foetus/neonate nutrient supply might be a crucial determinant of individual programming of body weight set point. The hypothalamus-adipose axis plays a pivotal role in the maintenance of energy homoeostasis controlling the nutritional status and energy storage level. The perinatal period largely corresponds to the period of brain maturation, neuronal differentiation and active adipogenesis in rodents. Numerous dams and/or foetus/neonate dietary manipulation models were developed to investigate the mechanisms underlying perinatal programming in rodents. These models showed several common offspring hypothalamic consequences such as impaired neurogenesis, neuronal functionality, nuclei structural organisation and feeding circuitry hardwiring. These alterations led to a persistent reprogrammed appetite system that favoured the orexigenic pathways, leptin/insulin resistance and hyperphagia. Impaired hypothalamic sympathetic outflow to adipose tissue and/or reduced innervation may also account for modified fat cell metabolism. Thus, enhanced adipogenesis and/or lipogenesis capacities may predispose the offspring to fat accumulation. Abnormal hypothalamus-adipose axis circadian rhythms were also evidenced. This review mainly focuses on studies in rodents. It highlights hormonal and epigenetic mechanisms responsible for long-lasting programming of energy balance in the offspring. Dietary supplementation may provide a therapeutic option using a specific regimen for reversing adverse programming outcomes in humans.",
"Substantial evidence demonstrated that maternal dietary nutrients can significantly determine the susceptibility to developing metabolic disorders in the offspring. Therefore, we aimed to investigate the later-life effects of maternal and postweaning diets interaction on epigenetic modification of the central nervous system in the offspring. We examined the effects of dams fed a high-fat, high-sucrose (FS) diet during pregnancy and lactation and weaned to FS diet continuously until 32 weeks of age. Then, DNA methylation and gene expressions of hypothalamic proopiomelanocortin (POMC) and melanocortin receptor 4 (MC4R) were determined in the offspring. Offspring of FS diet had heavier body weight, impaired glucose tolerance, decreased insulin sensitivity and higher serum leptin level at 32-week age (p < 0.05). The expression of POMC and MC4R genes were significantly increased in offspring exposed to FS diet during gestation, lactation and into 32-week age (p < 0.05). Consistently, hypomethylation of POMC promoter in the hypothalamus occurred in the FS diet offspring (p < 0.05), compared with the C group. However, no methylation was detected of MC4R promoter in both the two groups. Furthermore, POMC-specific methylation (%) was negatively associated with glucose response to a glucose load (r = -0.273, p = 0.039). Maternal and post-weaning high-fat diet predisposes the offspring for obesity, glucose intolerance and insulin resistance in later life. Our findings can advance our thinking around the DNA methylation status of the promoter of the POMC and MC4R genes between long-term high-fat, high-sucrose diet and glucose homeostasis in mouse.",
"Epidemiological studies show a link between low birthweight and increased obesity. In contrast, slow growth during the lactation period reduces obesity risk. The present study investigates the potential underlying mechanisms of these observations. Rats were established as follows: (i) control animals [offspring of control dams fed a 20% (w/v) protein diet], (ii) recuperated animals [offspring of dams fed an isocaloric low-protein (8%, w/v) diet during pregnancy and nursed by control dams], and (iii) postnatal low protein animals (offspring of control dams nursed by low-protein-fed dams). Serum and brains were collected from fed and fasted animals at weaning. Expression of hypothalamic energy balance genes was assessed using in situ hybridization. Recuperated pups were smaller at birth, but caught up with controls by day 21 and gained more weight than controls between weaning and 12 weeks of age (P<0.05). At 21 days, they were hypoleptinaemic compared with controls in the fed state, with generally comparable hypothalamic gene expression. Postnatal low protein offspring had significantly lower body weights than controls at weaning and 12 weeks of age (P<0.001). At 21 days, they were hypoglycaemic, hypoinsulinaemic and hypoleptinaemic. Leptin receptor gene expression in the arcuate nucleus was increased in postnatal low protein animals compared with controls. Consistent with hypoleptinaemia, hypothalamic gene expression for the orexigenic neuropeptides NPY (neuropeptide Y) and AgRP (Agouti-related peptide) was increased, and that for the anorexigenic neuropeptides POMC (pro-opiomelanocortin) and CART (cocaine- and amphetamine-regulated transcript) was decreased. These results suggest that the early nutritional environment can affect the development of energy balance circuits and consequently obesity risk."
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A rare variant in the CELSR2 gene is associated with idiopathic scoliosis in a Swedish-Danish family with dominant segregation
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A Swedish pedigree with an autosomal dominant inheritance of idiopathic scoliosis was initially studied by genetic linkage analysis, prioritising genomic regions for further analysis. This revealed a locus on chromosome 1 with a putative risk haplotype shared by all affected individuals. Two affected individuals were subsequently exome-sequenced, identifying a rare, non-synonymous variant in the CELSR2 gene. This variant is rs141489111, a c.G6859A change in exon 21 (NM_001408), leading to a predicted p.V2287I (NP_001399.1) change. This variant was found in all affected members of the pedigree, but showed reduced penetrance. Analysis of tagging variants in CELSR1-3 in a set of 1739 Swedish-Danish scoliosis cases and 1812 controls revealed significant association (p = 0.0001) to rs2281894, a common synonymous variant in CELSR2. This association was not replicated in case-control cohorts from Japan and the US. No association was found to variants in CELSR1 or CELSR3. Our findings suggest a rare variant in CELSR2 as causative for idiopathic scoliosis in a family with dominant segregation and further highlight common variation in CELSR2 in general susceptibility to idiopathic scoliosis in the Swedish-Danish population. Both variants are located in the highly conserved GAIN protein domain, which is necessary for the auto-proteolysis of CELSR2, suggesting its functional importance.
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"The ease of isolating mutations in zebrafish will contribute to an understanding of a variety of processes common to all vertebrates. To facilitate genetic analysis of such mutations, we have identified DNA polymorphisms closely linked to each of the 25 centromeres of zebrafish, placed centromeres on the linkage map, increased the number of mapped PCR-based markers to 652, and consolidated the number of linkage groups to the number of chromosomes. This work makes possible centromere-linkage analysis, a novel, rapid method to assign mutations to a specific linkage group using half-tetrads.",
"Idiopathic scoliosis is a form of spinal deformity that affects 2-3% of children and results in curvature of the spine without structural defects of the vertebral units. The pathogenesis of idiopathic scoliosis remains poorly understood, in part due to the lack of a relevant animal model. We performed a forward mutagenesis screen in zebrafish to identify new models for idiopathic scoliosis. We isolated a recessive zebrafish mutant, called skolios, which develops isolated spinal curvature that arises independent of vertebral malformations. Using meiotic mapping and whole genome sequencing, we identified a nonsense mutation in kinesin family member 6 (kif6(gw326) ) unique to skolios mutants. Three additional kif6 frameshift alleles (gw327, gw328, gw329) were generated with transcription activator-like effector nucleases (TALENs). Zebrafish homozygous or compound heterozygous for kif6 frameshift mutations developed a scoliosis phenotype indistinguishable from skolios mutants, confirming that skolios is caused by the loss of kif6. Although kif6 may play a role in cilia, no evidence for cilia dysfunction was seen in kif6(gw326) mutants. Overall, these findings demonstrate a novel role for kif6 in spinal development and identify a new candidate gene for human idiopathic scoliosis.",
"The G protein-coupled receptor (GPCR) Proteolysis Site (GPS) of cell-adhesion GPCRs and polycystic kidney disease (PKD) proteins constitutes a highly conserved autoproteolysis sequence, but its catalytic mechanism remains unknown. Here, we show that unexpectedly the ∼40-residue GPS motif represents an integral part of a much larger ∼320-residue domain that we termed GPCR-Autoproteolysis INducing (GAIN) domain. Crystal structures of GAIN domains from two distantly related cell-adhesion GPCRs revealed a conserved novel fold in which the GPS motif forms five β-strands that are tightly integrated into the overall GAIN domain. The GAIN domain is evolutionarily conserved from tetrahymena to mammals, is the only extracellular domain shared by all human cell-adhesion GPCRs and PKD proteins, and is the locus of multiple human disease mutations. Functionally, the GAIN domain is both necessary and sufficient for autoproteolysis, suggesting an autoproteolytic mechanism whereby the overall GAIN domain fine-tunes the chemical environment in the GPS to catalyse peptide bond hydrolysis. Thus, the GAIN domain embodies a unique, evolutionarily ancient and widespread autoproteolytic fold whose function is likely relevant for GPCR signalling and for multiple human diseases.",
"Adolescent idiopathic scoliosis (AIS) is a complex inherited spinal deformity whose etiology has been elusive. While common genetic variants are associated with AIS, they explain only a small portion of disease risk. To explore the role of rare variants in AIS susceptibility, exome sequence data of 391 severe AIS cases and 843 controls of European ancestry were analyzed using a pathway burden analysis in which variants are first collapsed at the gene level then by Gene Ontology terms. Novel non-synonymous/splice-site variants in extracellular matrix genes were significantly enriched in AIS cases compared with controls (P = 6 × 10(-9), OR = 1.7, CI = 1.4-2.0). Specifically, novel variants in musculoskeletal collagen genes were present in 32% (126/391) of AIS cases compared with 17% (146/843) of in-house controls and 18% (780/4300) of EVS controls (P = 1 × 10(-9), OR = 1.9, CI = 1.6-2.4). Targeted resequencing of six collagen genes replicated this association in combined 919 AIS cases (P = 3 × 10(-12), OR = 2.2, CI = 1.8-2.7) and revealed a highly significant single-gene association with COL11A2 (P = 6 × 10(-9), OR = 3.8, CI = 2.6-7.2). Importantly, AIS cases harbor mainly non-glycine missense mutations and lack the clinical features of monogenic musculoskeletal collagenopathies. Overall, our study reveals a complex genetic architecture of AIS in which a polygenic burden of rare variants across extracellular matrix genes contributes strongly to risk.",
"Research focused on cilia as extremely important cellular organelles has flourished in recent years. A thorough understanding of cilia regulation and function is critical, as disruptions of cilia structure and/or function have been linked to numerous human diseases and disorders. The tropical freshwater zebrafish is an excellent model organism in which to study cilia structure and function. We can readily image cilia and their motility in embryonic structures including Kupffer's vesicle during somite stages and the pronephros from 1 day postfertilization onward. Here, we describe how to image cilia by whole-mount immunofluorescence, transverse cryosection/immunohistochemistry, and transmission electron microscopy. We also describe how to obtain videos of cilia motility in living embryos.",
"alpha-Latrotoxin is a potent stimulator of neurosecretion. Its action requires extracellular binding to high affinity presynaptic receptors. Neurexin I alpha was previously described as a high affinity alpha-latrotoxin receptor that binds the toxin only in the presence of calcium ions. Therefore, the interaction of alpha-latrotoxin with neurexin I alpha cannot explain how alpha-latrotoxin stimulates neurotransmitter release in the absence of calcium. We describe molecular cloning and functional expression of the calcium-independent receptor of alpha-latrotoxin (CIRL), which is a second high affinity alpha-latrotoxin receptor that may be the major mediator of alpha-latrotoxin's effects. CIRL appears to be a novel orphan G-protein-coupled receptor, a member of the secretin receptor family. In contrast with other known serpentine receptors, CIRL has two subunits of the 120 and 85 kDa that are the result of endogenous proteolytic cleavage of a precursor polypeptide. CIRL is found in brain where it is enriched in the striatum and cortex. Expression of CIRL in chromaffin cells increases the sensitivity of the cells to the effects of alpha-latrotoxin, demonstrating that this protein is functional in coupling to secretion. Syntaxin, a component of the fusion complex, copurifies with CIRL on an alpha-latrotoxin affinity column and forms stable complexes with this receptor in vitro. Interaction of CIRL with a specific presynaptic neurotoxin and with a component of the docking-fusion machinery suggests its role in regulation of neurosecretion.",
"We present here the automated structure solution pipeline \"autoSHARP.\" It is built around the heavy-atom refinement and phasing program SHARP, the density modification program SOLOMON, and the ARP/wARP package for automated model building and refinement (using REFMAC). It allows fully automated structure solution, from merged reflection data to an initial model, without any user intervention. We describe and discuss the preparation of the user input, the data flow through the pipeline, and the various results obtained throughout the procedure."
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Molecular and cellular mechanisms of spinal cord regeneration in zebrafish
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To determine the molecular and cellular mechanisms of spinal cord regeneration in zebrafish.
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"In contrast to mammals, zebrafish regenerate spinal motor neurons. During regeneration, developmental signals are re-deployed. Here, we show that, during development, diffuse serotonin promotes spinal motor neuron generation from pMN progenitor cells, leaving interneuron numbers unchanged. Pharmacological manipulations and receptor knockdown indicate that serotonin acts at least in part via 5-HT1A receptors. In adults, serotonin is supplied to the spinal cord mainly (90%) by descending axons from the brain. After a spinal lesion, serotonergic axons degenerate caudal to the lesion but sprout rostral to it. Toxin-mediated ablation of serotonergic axons also rostral to the lesion impaired regeneration of motor neurons only there. Conversely, intraperitoneal serotonin injections doubled numbers of new motor neurons and proliferating pMN-like progenitors caudal to the lesion. Regeneration of spinal-intrinsic serotonergic interneurons was unaltered by these manipulations. Hence, serotonin selectively promotes the development and adult regeneration of motor neurons in zebrafish.",
"Increase in serotonin (5-HT) transmission has profound antidepressant effects and has been associated with an increase in adult neurogenesis. The present study was aimed at screening the 5-HT receptor subtypes involved in the regulation of cell proliferation in the subgranular layer (SGL) of the dentate gyrus (DG) and the subventricular zone (SVZ) and to determine the long-term changes in adult neurogenesis. The 5-HT1A, 5-HT1B, and 5-HT2 receptor subtypes were chosen for their implication in depression and their location in/or next to these regions. Using systemic administration of various agonists and antagonists, we show that the activation of 5-HT1A heteroreceptors produces similar increases in the number of bromodeoxyuridine-labeled cells in the SGL and the SVZ (about 50% over control), whereas 5-HT2A and 5-HT2C receptor subtypes are selectively involved in the regulation of cell proliferation in each of these regions. The activation of 5-HT2C receptors, largely expressed by the choroid plexus, produces a 56% increase in the SVZ, while blockade of 5-HT2A receptors produces a 63% decrease in the number of proliferating cells in the SGL. In addition to the influence of 5-HT1B autoreceptors on 5-HT terminals in the hippocampus and ventricles, 5-HT1B heteroreceptors also regulate cell proliferation in the SGL. These data indicate that multiple receptor subtypes mediate the potent, partly selective of each neurogenic zone, stimulatory action of 5-HT on adult brain cell proliferation. Furthermore, both acute and chronic administration of selective 5-HT1A and 5-HT2C receptor agonists produce consistent increases in the number of newly formed neurons in the DG and/or olfactory bulb, underscoring the beneficial effects of 5-HT on adult neurogenesis.",
"The hypothesis that serotonin (5-HT) influences the onset of differentiation (cessation of division) of prospective 5-HT target neurons during embryogenesis was tested by administering the 5-HT depleting drug p-chlorophenylalanine (pCPA) to pregnant rats and dating the time of last cell division for fetal neurons using long survival 3H-thymidine autoradiography. PCPA specifically retarded the onset of neuronal differentiation in brain regions known to contain 5-HT terminals or to have a high 5-HT content in the adult (5-HT target cells). Conversely, the 'stress' of daily vehicle injections accelerated onset of differentiation in these regions, possibly due to stimulation of 5-HT synthesis by glucocorticoids. These data support the model of 5-HT as a humoral signal for the differentiation of cells later recognized by 5-HT neurons as appropriate targets for synaptogenesis."
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what is coeliac disease
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Coeliac disease is a chronic enteropathy that remains a challenge for the clinician, due to its atypical manifestations and etiopathogenic complexity.
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[
"The aim of this study was to evaluate the oral manifestations of celiac disease (CD), the chemical composition of dental enamel, and the occurrence of CD in children with dental enamel defects (DEDs). In the study, 52 children with CD and 52 controls were examined for DEDs, recurrent aphthous stomatitis (RAS), dental caries experience, and salivary parameters. In addition, 10 exfoliated primary enamel molars from each group were analyzed by energy dispersive x-ray spectroscopy and Fourier transform infrared spectroscopy. Fifty children with DEDs were submitted to CD diagnosis. Among the children with CD, a higher prevalence of DEDs (P = .00001) and RAS (P = .0052), lower caries experience (P = .0024), and reduction of salivary flow (P = .0060) were observed. Dental enamel from the children with CD demonstrated a lower calcium-to-phosphorus ratio (P = .0136), but no difference in the carbonate-to-phosphate ratio (P = .5862) was observed. In the multivariate analysis, CD was a protective factor for caries (OR = 0.74) and a risk factor for RAS (OR3.23). The children with CD presented with more RAS, DEDs, reduction of salivary flow, and chemical alterations in the enamel.",
"AIM.: The aim of the clinical-statistic study was to evaluate the prevalence of the different oral manifestations in a sample of coeliac patients, in comparison with a control group of healthy subjects. Moreover, a second objective was to determine if the clinical oral examination is useful as a diagnostic tool of screening for atypical forms of coeliac disease (CD). METHODS.: The enrolment of 300 coeliac patients, aged between 4 and 13 years (mean age 8.16), was carried out at the Pediatric Dentistry Unit in patients sent from the Pediatric Gastroenterology Unit of the PTV Hospital, University of Rome Tor Vergata. The control group was composed of 300 healthy subjects, age-matched (mean age 8.29), enrolled from the Pediatric Dentistry Unit. The patients were examined for hard tissues (enamel hypoplasia, dental caries), soft tissues (recurrent aphthous stomatitis RAS, atrophic glossitis, geographic tongue) and delay dental eruption. Enamel defects were classified according to Aine's criteria, while dental caries was recorded as dmft/DMFT indices. Statistical analysis was carried out by using SPSS/PC+ Software. Differences between case and control groups were tested using Paired samples T-test, and Chi-Square Test, depending on the variable considered. The minimal level of significance of the differences was fixed at p≤0.05 for all the procedures. RESULTS.: Statistical differences between groups were observed for the prevalence of enamel defects (p=0.0001), RAS (p=0.005), delay in dental eruption (p=0.0001), but not for the prevalence of atrophic glossitis (p=0.664). Differences in symmetrical distribution and a chronologic coherence of enamel defects were statistically significant between CD and control groups (p=0.0001). Regarding dental caries, the coeliac patients had higher indexes of caries than healthy subjects, both in deciduous teeth (dmft 2.31±1.84 vs 1.42±1.13; p= 0.021) and permanent teeth (DMFT 2.97±1.74 vs 1.74±1.64; p=0.0001). CONCLUSIONS.: The clinical oral examination should be considered a diagnostic tool for the characterization of subjects affected by silent-atypical forms of CD.",
"The aim of this study was to investigate whether Dutch children with proven coeliac disease show specific dental enamel defects, and to asses whether children with the same gastrointestinal complaints, but proved no-coeliac disease, lack these specific dental enamel defects. Eighty-one children (53 coeliac patients and 28 control subjects) were examined during the period 2003-2004 in the Oral Surgery Outpatient Clinic of the Academic Medical Centre in Amsterdam. Twenty-nine (55%) coeliac patients had enamel defects against 5 (18%) control subjects. In the coeliac disease group, the enamel defects were diagnosed as specific in 20 (38%) children, compared with 1 (4%) in the control group. Statistical analysis showed significantly more specific enamel defects in children with coeliac disease than in children in the control group (chi(2) = 12.62, d.f. = 2, P = 0.002). This study showed significantly more specific enamel defects in Dutch children with coeliac disease as compared with children in the control group. Dentists could play an important role in recognizing patients with coeliac disease.",
"Recent epidemiologic studies in Europe using antigliadin (AGA) and anti-endomysium antibodies (AEA) for initial screening have shown that the overall prevalence of celiac disease (CD) is about 1:300. There are no comparable scientific data for the USA, where CD is considered rare. The main aim of this study was to determine the prevalence of increased AEA in healthy blood donors in the USA. Sera from 2000 healthy blood donors were screened for IgG AGA and IgA AGA with an enzyme-linked immunosorbent assay test. All those with increased AGA levels, those with intermediate levels, and random samples with low levels were tested for AEA, using both monkey esophagus (ME) and human umbilical cord (HUC) cryosections as substrates. The mean age of the blood donors was 39 years, with 52% being men, 85.2% being Caucasian, 11.8% African-American, 1.5% Asian, and 1.5% Hispanic. Eight healthy blood donors had positive AEA tests on both monkey esophagus and human umbilical cord. Among the eight subjects with increased AEA levels seven were Caucasian and one was African-American. All the four examined AEA-positive donors carried the known susceptibility alleles for CD. The prevalence of increased AEA levels in healthy blood donors in the USA is 1:250 (8:2000). This is similar to that reported in countries in Europe, where subsequent small-intestinal biopsies have confirmed CD in all those with AEA positivity. On the basis of a high positive predictive value of the AEA antibody test, it is likely that the eight blood donors identified in this study have CD. These data suggest that CD is not rare in the USA and that there is need for a large-scale epidemiologic study to determine the precise prevalence of the disease in the USA.",
"Enamel defects in the permanent teeth of patients with coeliac disease (CD) are often reported as an atypical manifestation, sometimes being suggestive of an undiagnosed atypical disease. We proposed to explore the pathogenesis of these oral defects, which are poorly studied. Sequence analyses of proteins from gluten (gliadins) and of proline-rich enamel proteins (amelogenin and ameloblastin) suggested the presence of common antigenic motifs. Therefore, we analyzed, by ELISA and western blotting, the reactivity of sera from patients with CD against gliadin and enamel-derived peptides. Correlation analyses between the levels of specific antibodies against gliadin and enamel derived peptides and inhibition experiments confirmed the presence of cross-reactive antibodies. Immunoblot analysis revealed that the most prominent component in enamel matrix derivative (of approximately 18.6 kDa), identified by an amelogenin-specific antibody, is recognized by sera from patients with CD; in addition, several fractions of pure gliadin were recognized by amelogenin-specific antibody. In agreement, sera from mice immunized with enamel matrix-derived proteins generated antibodies that recognized a peptide (of approximately 21.2 kDa) derived from gliadin. In conclusion, antibodies against gliadin generated in patients with CD can react in vitro with a major enamel protein. The involvement of anti-gliadin serum in the pathogenesis of enamel defects in children with untreated CD can be hypothesized on the basis of these novel results."
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Influence of plasmid copy number on the interaction of a heterologous AND gate circuit with the host
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Synthetic biology approaches commonly introduce heterologous gene networks into a host to predictably program cells, with the expectation of the synthetic network being orthogonal to the host background. However, introduced circuits may interfere with the host's physiology, either indirectly by posing a metabolic burden and/or through unintended direct interactions between parts of the circuit with those of the host, affecting functionality. Here we used RNA-Seq transcriptome analysis to quantify the interactions between a representative heterologous AND gate circuit and the host Escherichia coli under various conditions including circuit designs and plasmid copy numbers. We show that the circuit plasmid copy number outweighs circuit composition for their effect on host gene expression with medium-copy number plasmid showing more prominent interference than its low-copy number counterpart. In contrast, the circuits have a stronger influence on the host growth with a metabolic load increasing with the copy number of the circuits. Notably, we show that variation of copy number, an increase from low to medium copy, caused different types of change observed in the behavior of components in the AND gate circuit leading to the unbalance of the two gate-inputs and thus counterintuitive output attenuation. The study demonstrates the circuit plasmid copy number is a key factor that can dramatically affect the orthogonality, burden and functionality of the heterologous circuits in the host chassis. The results provide important guidance for future efforts to design orthogonal and robust gene circuits with minimal unwanted interaction and burden to their host.
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[
"We designed and constructed versatile modular genetic logic gates in bacterial cells. These function as digital logic 1-input Buffer gate, 2-input and 3-input AND gates with one inverted input and integrate multiple chemical input signals in customised logic manners. Such rapidly engineered devices serve to achieve increased sensing signal selectivity.",
"Cells navigate environments, communicate and build complex patterns by initiating gene expression in response to specific signals. Engineers seek to harness this capability to program cells to perform tasks or create chemicals and materials that match the complexity seen in nature. This Review describes new tools that aid the construction of genetic circuits. Circuit dynamics can be influenced by the choice of regulators and changed with expression 'tuning knobs'. We collate the failure modes encountered when assembling circuits, quantify their impact on performance and review mitigation efforts. Finally, we discuss the constraints that arise from circuits having to operate within a living cell. Collectively, better tools, well-characterized parts and a comprehensive understanding of how to compose circuits are leading to a breakthrough in the ability to program living cells for advanced applications, from living therapeutics to the atomic manufacturing of functional materials.",
"Synthetic biology is increasingly used to develop sophisticated living devices for basic and applied research. Many of these genetic devices are engineered using multi-copy plasmids, but as the field progresses from proof-of-principle demonstrations to practical applications, it is important to develop single-copy synthetic modules that minimize consumption of cellular resources and can be stably maintained as genomic integrants. Here we use empirical design, mathematical modeling, and iterative construction and testing to build single-copy, bistable toggle switches with improved performance and reduced metabolic load that can be stably integrated into the host genome. Deterministic and stochastic models led us to focus on basal transcription to optimize circuit performance and helped to explain the resulting circuit robustness across a large range of component expression levels. The design parameters developed here provide important guidance for future efforts to convert functional multi-copy gene circuits into optimized single-copy circuits for practical, real-world use.",
"A transcriptional response to singlet oxygen in Rhodobacter sphaeroides is controlled by the group IV sigma factor sigma(E) and its cognate anti-sigma ChrR. Crystal structures of the sigma(E)/ChrR complex reveal a modular, two-domain architecture for ChrR. The ChrR N-terminal anti-sigma domain (ASD) binds a Zn(2+) ion, contacts sigma(E), and is sufficient to inhibit sigma(E)-dependent transcription. The ChrR C-terminal domain adopts a cupin fold, can coordinate an additional Zn(2+), and is required for the transcriptional response to singlet oxygen. Structure-based sequence analyses predict that the ASD defines a common structural fold among predicted group IV anti-sigmas. These ASDs are fused to diverse C-terminal domains that are likely involved in responding to specific environmental signals that control the activity of their cognate sigma factor."
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RNA chaperone Hfq and the catabolite repression control protein act as post-transcriptional regulators during carbon catabolite repression
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In Pseudomonas aeruginosa the RNA chaperone Hfq and the catabolite repression control protein (Crc) act as post-transcriptional regulators during carbon catabolite repression (CCR). In this regard Crc is required for full-fledged Hfq-mediated translational repression of catabolic genes. RNAseq based transcriptome analyses revealed a significant overlap between the Crc and Hfq regulons, which in conjunction with genetic data supported a concerted action of both proteins. Biochemical and biophysical approaches further suggest that Crc and Hfq form an assembly in the presence of RNAs containing A-rich motifs, and that Crc interacts with both, Hfq and RNA. Through these interactions, Crc enhances the stability of Hfq/Crc/RNA complexes, which can explain its facilitating role in Hfq-mediated translational repression. Hence, these studies revealed for the first time insights into how an interacting protein can modulate Hfq function. Moreover, Crc is shown to interfere with binding of a regulatory RNA to Hfq, which bears implications for riboregulation. These results are discussed in terms of a working model, wherein Crc prioritizes the function of Hfq toward utilization of favored carbon sources.
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[
"Synthesis of the Pseudomonas aeruginosa aliphatic amidase was repressed severely by succinate and malate and less severely by glucose, acetate or lactate. Amidase synthesis in inducible and constitutive strains was stimulated by cyclic AMP, which also gave partial relief to catabolite repression produced by the addition of lactate to cultures growing in pyruvate medium. Mutants which were resistant to catabolite repression were isolated from succinate+lactamide medium.",
"Small trans-encoded RNAs (sRNAs) modulate the translation and decay of mRNAs in bacteria. In Gram-negative species, antisense regulation by trans-encoded sRNAs relies on the Sm-like protein Hfq. In contrast to this, Hfq is dispensable for sRNA-mediated riboregulation in the Gram-positive species studied thus far. Here, we provide evidence for Hfq-dependent translational repression in the Gram-positive human pathogen Listeria monocytogenes, which is known to encode at least 50 sRNAs. We show that the Hfq-binding sRNA LhrA controls the translation and degradation of its target mRNA by an antisense mechanism, and that Hfq facilitates the binding of LhrA to its target. The work presented here provides the first experimental evidence for Hfq-dependent riboregulation in a Gram-positive bacterium. Our findings indicate that modulation of translation by trans-encoded sRNAs may occur by both Hfq-dependent and -independent mechanisms, thus adding another layer of complexity to sRNA-mediated riboregulation in Gram-positive species.",
"Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic lung infections in cystic fibrosis patients and is a major source of nosocomial infections. This bacterium controls many virulence factors by using two quorum-sensing systems, las and rhl. The las system is composed of the LasR regulator protein and its cell-to-cell signal, N-(3-oxododecanoyl) homoserine lactone, and the rhl system is composed of RhlR and the signal N-butyryl homoserine lactone. A third intercellular signal, the Pseudomonas quinolone signal (PQS; 2-heptyl-3-hydroxy-4-quinolone), also regulates numerous virulence factors. PQS synthesis requires the expression of multiple operons, one of which is pqsABCDE. Previous experiments showed that the transcription of this operon, and therefore PQS production, is negatively regulated by the rhl quorum-sensing system and positively regulated by the las quorum-sensing system and PqsR (also known as MvfR), a LysR-type transcriptional regulator protein. With the use of DNA mobility shift assays and beta-galactosidase reporter fusions, we have studied the regulation of pqsR and its relationship to pqsA, lasR, and rhlR. We show that PqsR binds the promoter of pqsA and that this binding increases dramatically in the presence of PQS, implying that PQS acts as a coinducer for PqsR. We have also mapped the transcriptional start site for pqsR and found that the transcription of pqsR is positively regulated by lasR and negatively regulated by rhlR. These results suggest that a regulatory chain occurs where pqsR is under the control of LasR and RhlR and where PqsR in turn controls pqsABCDE, which is required for the production of PQS.",
"The RNA chaperone Hfq is an Sm protein that facilitates base pairing between bacterial small RNAs (sRNAs) and mRNAs involved in stress response and pathogenesis. Hfq possesses an intrinsically disordered C-terminal domain (CTD) that may tune the function of the Sm domain in different organisms. In Escherichia coli, the Hfq CTD increases kinetic competition between sRNAs and recycles Hfq from the sRNA-mRNA duplex. Here, de novo Rosetta modeling and competitive binding experiments show that the acidic tip of the E. coli Hfq CTD transiently binds the basic Sm core residues necessary for RNA annealing. The CTD tip competes against non-specific RNA binding, facilitates dsRNA release, and prevents indiscriminate DNA aggregation, suggesting that this acidic peptide mimics nucleic acid to auto-regulate RNA binding to the Sm ring. The mechanism of CTD auto-inhibition predicts the chaperone function of Hfq in bacterial genera and illuminates how Sm proteins may evolve new functions.",
"Bacterial Hfq is a protein that plays an important role in the regulation of genes in cooperation with sRNAs. Escherichia coli Hfq (EcHfq) has two or more sites that bind RNA(s) including U-rich and/or the poly(A) tail of mRNA. However, functional and structural information about Bacillus subtilis Hfq (BsHfq) including the RNA sequences that specifically bind to it remain unknown. Here, we describe RNA aptamers including fragment (AG)(3)A that are recognized by BsHfq and crystal structures of the BsHfq-(AG)(3)A complex at 2.2 Å resolution. Mutational and structural studies revealed that the RNA fragment binds to the distal site, one of the two binding sites on Hfq, and identified amino acid residues that are critical for sequence-specific interactions between BsHfq and (AG)(3)A. In particular, R32 appears to interact with G bases in (AG)(3)A. Poly(A) also binds to the distal site of EcHfq, but the overall RNA structure and protein-RNA interaction patterns engaged in the R32 residues of BsHfq-(AG)(3)A differ from those of EcHfq-poly(A). These findings provide novel insight into how the Hfq homologue recognizes RNA.",
"Bacterial small RNAs (sRNAs) are key elements of regulatory networks that modulate gene expression. The sRNA RydC of Salmonella sp. and Escherichia coli is an example of this class of riboregulators. Like many other sRNAs, RydC bears a 'seed' region that recognises specific transcripts through base-pairing, and its activities are facilitated by the RNA chaperone Hfq. The crystal structure of RydC in complex with E. coli Hfq at a 3.48 Å resolution illuminates how the protein interacts with and presents the sRNA for target recognition. Consolidating the protein-RNA complex is a host of distributed interactions mediated by the natively unstructured termini of Hfq. Based on the structure and other data, we propose a model for a dynamic effector complex comprising Hfq, small RNA, and the cognate mRNA target.",
"Pseudomonas aeruginosa is an important pathogenic and environmental bacterium, with the most widely studied strain being PAO1. Using the PAO1 reference cosmid library and the recently completed PAO1 genome sequence, we have mapped a minimal tiling path across the genome using a two-step strategy. First, we sequenced both ends of a set of over 500 random and previously mapped clones to create a backbone. Second, we end-sequenced a second set of cosmid clones that were identified to lie within the larger gaps using hybridization of the reference library filters with probes designed against sequences at the center of each gap. The minimal tiling path was calculated using the program Domino (http://www.bit.uq.edu.au/download/), with the overlap between adjacent clones set to 5 kb (where possible) to minimize the chance of truncating genes. This yielded a minimal tiling cosmid library (334 clones) covering 93.7% of the genome in 57 contigs. This library has reduced to a workable set the number of clones required to represent the majority of the P. aeruginosa genome and gives the precise location of each cosmid, enabling most genes of interest to be located on clones without further screening. This library should prove a useful resource to accelerate functional analysis of the P. aeruginosa genome."
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what is the relationship between seaweed and microbes?
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The ability to recognize and respond to the presence of microbes is an essential strategy for seaweeds to survive in the marine environment, but understanding of molecular seaweed-microbe interactions is limited.
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"Sugar starvation exerted by sub-10 mM levels of sucrose on Arabidopsis T87 suspension-cultured cells triggered marked accumulation of the transcripts of genes for E1beta and E2 subunit of the branched-chain alpha-keto acid dehydrogenase complex. Similar levels of sugar starvation increased the luciferase activity in transgenic tobacco BY-2 lines expressing the Arabidopsis E1beta- or E2-promoter-luciferase fusion gene. These results indicate that sugar levels tightly regulate the E1beta and E2 promoter activity in the heterologous plant system. We further showed in the transgenic tobacco BY-2 lines that sugar-starvation-induced activation of the E1beta and E2 promoters was prevented by K-252a, an inhibitor of Ser/Thr protein kinase, and was enhanced by okadaic acid, an inhibitor of protein phosphatases. By contrast, the cauliflower mosaic virus 35S promoter activity in sugar-starved BY-2 cells was not significantly affected by K-252a and only slightly enhanced by okadaic acid. Taken together, we propose that transcriptional activation of genes for the branched-chain alpha-keto acid dehydrogenase complex and its modulation by specific protein kinases/phosphatases are of critical importance in branched-chain amino acid catabolism in plant cells under sugar starvation.",
"Fucoidan, a mixture of sulfated fucose-containing polysaccharides, was prepared from the algal bodies of Cladosiphon okamuranus (class Phaeophyceae, order Chordariales, family Chordariaceae) with a yield of 2.0% of the wet weight of the alga. To obtain enzymes that digest the fucoidan, we screened bacteria in the guy contents of the sea cucumber Stichopus japonicus for their ability to decrease the fucoidan in their culture media, and successfully isolated one bacterial strain that could decrease it. The bacterial strain was gram-negative and possessed menaquinone 7 as the predominant respiratory quinone, and the GC content of its genomic DNA was 52%. The results of the phylogenetic analysis of its 16S ribosomal DNA sequence indicated that the bacterial strain was a member of the division \"Verrucomicrobia.\" However, as the bacterial strain is phylogenetically and phenotypically distinct from verrucomicrobial species described previously, the strain was assumed to be a new member of the division \"Verrucomicrobia.\" When the bacterial strain was cultivated in an algal fucoidan-containing medium, the strain decreased fucoidan from C. okamuranus (44%), Nemacystus decipiens (19%), Laminaria japonica (31%), Kjellmaniella crassifolia (23%), sporophyl of Undaria pinnatifida (22%), Fucus vesiculosus (42%), and Ascophyllum nodosum (61%).",
"New evidence suggests a role for the plant growth hormone auxin in pathogenesis and disease resistance. Bacterial infection induces the accumulation of indole-3-acetic acid (IAA), the major type of auxin, in rice (Oryza sativa). IAA induces the expression of expansins, proteins that loosen the cell wall. Loosening the cell wall is key for plant growth but may also make the plant vulnerable to biotic intruders. Here, we report that rice GH3-8, an auxin-responsive gene functioning in auxin-dependent development, activates disease resistance in a salicylic acid signaling- and jasmonic acid signaling-independent pathway. GH3-8 encodes an IAA-amino synthetase that prevents free IAA accumulation. Overexpression of GH3-8 results in enhanced disease resistance to the rice pathogen Xanthomonas oryzae pv oryzae. This resistance is independent of jasmonic acid and salicylic acid signaling. Overexpression of GH3-8 also causes abnormal plant morphology and retarded growth and development. Both enhanced resistance and abnormal development may be caused by inhibition of the expression of expansins via suppressed auxin signaling.",
"Seaweeds of the Laurencia genus have a broad geographic distribution and are largely recognized as important sources of secondary metabolites, mainly halogenated compounds exhibiting diverse potential pharmacological activities and relevant ecological role as anti-epibiosis. Host-microbe interaction is a driving force for co-evolution in the marine environment, but molecular studies of seaweed-associated microbial communities are still rare. Despite the large amount of research describing the chemical compositions of Laurencia species, the genetic knowledge regarding this genus is currently restricted to taxonomic markers and general genome features. In this work we analyze the transcriptomic profile of L. dendroidea J. Agardh, unveil the genes involved on the biosynthesis of terpenoid compounds in this seaweed and explore the interactions between this host and its associated microbiome. A total of 6 transcriptomes were obtained from specimens of L. dendroidea sampled in three different coastal locations of the Rio de Janeiro state. Functional annotations revealed predominantly basic cellular metabolic pathways. Bacteria was the dominant active group in the microbiome of L. dendroidea, standing out nitrogen fixing Cyanobacteria and aerobic heterotrophic Proteobacteria. The analysis of the relative contribution of each domain highlighted bacterial features related to glycolysis, lipid and polysaccharide breakdown, and also recognition of seaweed surface and establishment of biofilm. Eukaryotic transcripts, on the other hand, were associated with photosynthesis, synthesis of carbohydrate reserves, and defense mechanisms, including the biosynthesis of terpenoids through the mevalonate-independent pathway. This work describes the first transcriptomic profile of the red seaweed L. dendroidea, increasing the knowledge about ESTs from the Florideophyceae algal class. Our data suggest an important role for L. dendroidea in the primary production of the holobiont and the role of Bacteria as consumers of organic matter and possibly also as nitrogen source. Furthermore, this seaweed expressed sequences related to terpene biosynthesis, including the complete mevalonate-independent pathway, which offers new possibilities for biotechnological applications using secondary metabolites from L. dendroidea.",
"Laboratory and field experiments were performed to assess the ecological roles of natural products produced by the Brazilian red seaweed Laurencia obtusa. Laboratory assays revealed that the natural concentration of the crude organic extract of L. obtusa significantly inhibited feeding by two herbivores: the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. It was verified that this chemically defensive action was due to halogenated sesquiterpenoid elatol, found to be the major natural product of this red seaweed. In addition, it was verified that the antifouling property of the chemicals produced by L. obtusa could make this red alga less attractive for fish grazing. Direct protection against two herbivore species and indirect protection against herbivory by fouling inibition constitute evidence that the major natural product from Brazilian L. obtusa plays multiple environmental roles, thereby increasing the adaptive value of these metabolites. On the other hand, the evidence reinforces the idea that marine natural products may have different functions in the sea.",
"Brown algae are one of the few eukaryotic lineages that have evolved complex multicellularity, together with Opisthokonts (animals, fungi) and Plantae (land plants, green and red algae). In these three lineages, biotic stresses induce similar local defense reactions. Animals and land plants also feature a systemic immune response, protecting the whole organism after an attack on one of its parts. However, the occurrence of systemic defenses has never been investigated in brown algae. We elicited selected parts of the kelp Laminaria digitata and monitored distant, nonchallenged areas of the same individual for subsequent defense reactions. A systemic reaction was detected following elicitation on a distant area, including an oxidative response, an increase in haloperoxidase activities and a stronger resistance against herbivory. Based on experiments with pharmacological inhibitors, the liberation of free fatty acids is proposed to play a key role in systemic signaling, reminiscent of what is known in land plants. This study is the first report, outside the phyla of Opisthokonts and Plantae, of an intraorganism communication leading to defense reactions. These findings indicate that systemic immunity emerged independently at least three times, as a consequence of convergent evolution in multicellular eukaryotic lineages.",
"Ethylene response factors (ERFs) are a large family of transcription factors (TFs) that have diverse functions in plant development and immunity. However, very little is known about the molecular regulation of these TFs in stone fruits during disease incidence. In the present study, we describe the identification of five peach ERFs (Pp-ERFs), aiming to elucidate their potential roles in defense against Xanthomonas campestris pv. pruni (Xcp), the causal agent of bacterial spot disease. The phylogenetic analysis along with sequence comparisons indicated that all Pp-ERFs are transcriptional activators belonging to groups IX and IIV ERFs. The transactivation capacity of these proteins was verified in vivo where they all induced the expression of the GUS reporter gene and in a GCC-dependent manner. The nuclear localization was also confirmed for two of these proteins, Pp-ERF2.b and Pp-ERF2.c, after their transient expression in onion epidermal cells. The induction kinetics of Pp-ERFs after inoculation with Xcp was determined by qRT-PCR. Except for Pp-ERF2.b, transcript levels of Pp-ERFs increased strongly and rapidly in the resistant 'Venture' compared to the susceptible 'BabyGold 5' cultivar after infection with Xcp. In contrast, the expression of Pp-ERF2.b was several-fold higher in the susceptible cultivar after bacterial infection. The expression of Pp-ERFs was also monitored after treating with signaling compounds; salicylic acid (SA) (1 mM), ethephon (1 mM) and methyl jasmonate (MeJA) (50 μM). Although the results generally emphasize the role of ethylene/jasmonic acid (ET/JA) signaling pathways in regulating the expression of Pp-ERFs, there was a coordination of the timing of ET/JA responses, suggesting compensatory rather than synergistic interactions between these pathways during defense against Xcp.",
"The aim of this study was to profile expression of mannuronan C5-epimerase (ManC5-E) genes of Laminaria digitata (Huds.) J. V. Lamour. under treatment with brown alga cell wall components known to induce defense reaction in this organism. After determining that incubation in the presence of homo-guluronates increased the accumulation of ManC5-E transcripts, we cloned a number of partial ManC5-E genes from nonelicited and elicited specimens. In addition to these fragments, previously identified genes from sporophyte and protoplast cDNA libraries were considered for a clustering analysis. Several groups of ManC5-E genes were observed, including groups containing sequences specific from nonelicited and elicited sporophytes, and sequences isolated from protoplasts. Quantitative real-time PCR experiments were then carried out using genes representative of different groups. Results of transcript accumulation during protoplast regeneration and sporophyte elicitation supported the hypothesis that specific C5-epimerase genes are recruited under pathogen attack, enabling L. digitata to modify its cell wall in response to environmental stimuli.",
"Plant disease resistance governed by quantitative trait loci (QTL) is predicted to be effective against a broad spectrum of pathogens and long lasting. Use of these QTL to improve crop species, however, is hindered because the genes contributing to the trait are not known. Five disease resistance QTL that colocalized with defense response genes were accumulated by marker-aided selection to develop blast-resistant varieties. One advanced backcross line carrying the major-effect QTL on chromosome (chr) 8, which included a cluster of 12 germin-like protein (OsGLP) gene members, exhibited resistance to rice (Oryza sativa) blast disease over 14 cropping seasons. To determine if OsGLP members contribute to resistance and if the resistance was broad spectrum, a highly conserved portion of the OsGLP coding region was used as an RNA interference trigger to silence a few to all expressed chr 8 OsGLP family members. Challenge with two different fungal pathogens (causal agents of rice blast and sheath blight diseases) revealed that as more chr 8 OsGLP genes were suppressed, disease susceptibility of the plants increased. Of the 12 chr 8 OsGLPs, one clustered subfamily (OsGER4) contributed most to resistance. The similarities of sequence, gene organization, and roles in disease resistance of GLP family members in rice and other cereals, including barley (Hordeum vulgare) and wheat (Triticum aestivum), suggest that resistance contributed by the chr 8 OsGLP is a broad-spectrum, basal mechanism conserved among the Gramineae. Natural selection may have preserved a whole gene family to provide a stepwise, flexible defense response to pathogen invasion.",
"We have constructed a genetic linkage map of peach [Prunus persica (L.) Batsch] consisting of RFLP, RAPD and morphological markers, based on 71 F2 individuals derived from the self-fertilization of four F1 individuals of a cross between 'New Jersey Pillar' and KV 77119. This progeny, designated as the West Virginia (WV) family, segregates for genes controlling canopy shape, fruit flesh color, and flower petal color, size and number. The segregation of 65 markers, comprising 46 RFLP loci, 12 RAPD loci and seven morphological loci, was analyzed. Low-copy genomic and cDNA probes were used in the RFLP analysis. The current genetic map for the WV family contains 47 markers assigned to eight linkage groups covering 332 centi Morgans (cM) of the peach nuclear genome. The average distance between two adjacent markers is 8 cM. Linkage was detected between Pillar (Pi) and double flowers (Dl) RFLP markers linked to Pi and flesh color (γ) loci were also found. Eighteen markers remain unassigned. The individuals analyzed for linkage were not a random sample of all F2 trees, as an excess of pillar trees were chosen for analysis. Because of this, Pi and eight other markers that deviated significantly from the expected Mendelian ratios (e.g., 1∶2∶1 or 3∶1) were not eliminated from the linkage analysis. Genomic clones that detect RFLPs in the WV family also detect significant levels of polymorphism among the 34 peach cultivars examined. Unique fingerprint patterns were created for all the cultivars using only six clones detecting nine RFLP fragments. This suggests that RFLP markers from the WV family have a high probability of being polymorphic in crosses generated with other peach cultivars, making them ideal for anchor loci. This possibility was examined by testing RFLP markers developed with the WV family in three other unrelated peach families. In each of these three peach families respectively 43%, 54% and 36% of RFLP loci detected in the WV family were also polymorphic. This finding supports the possibility that these RFLP markers may serve as anchor loci in many other peach crosses."
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Vitamin D Level and External-Induced Apical Root Resorption Following Fixed Orthodontic Treatment
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Adequate Vitamin D is essential for dental and skeletal health in children and adult. The purpose of this study was to assess the correlation of serum Vitamin D level with external-induced apical root resorption (EARR) following fixed orthodontic treatment.
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"Apical root resorption is an undesirable, but frequent side effect of orthodontic treatment, and therefore improvements in orthodontic techniques and materials are in constant development to decrease it. One of the most recently developed orthodontic techniques is the Bioefficient Therapy that uses contemporary orthodontic materials. Therefore, the primary objective of this study was to compare the amount of root resorption after orthodontic treatment between the simplified standard edgewise technique (group 1), the edgewise straight wire system (group 2), and the Bioefficient Therapy (group 3). It was also the purpose of this investigation to evaluate the amount of root resorption in the whole sample studied and the prevalence of root resorption in the upper and lower incisors. Thus, periapical radiographs were obtained with the long cone paralleling technique for the upper and lower incisors from 30 patients for each group. Root resorption was ranked by scores by 2 examiners who had an excellent intra and interexaminer calibration by Kendall concordance coefficient. Results of the Kruskal-Wallis test demonstrated that group 3 (Bioefficient Therapy) presented less root resorption than the others. It was speculated that the factors responsible for the lesser resorption in this technique were the use of heat-activated and superelastic wires with the bracket design in this technique as well as the use of a smaller rectangular stainless steel wire (0.018 x 0.025 inch) in a 0.022 x 0.028 inch slot during incisor retraction and the finishing stages, as compared to the other techniques. Considering the whole sample, there was no root resorption in 2.25% of the analyzed teeth. There was only a slight resorption in 42.56%, a moderate resorption in 53.37%, an accentuated resorption in 1.40% and an extreme root resorption in only 0.42% of the teeth. The prevalence of resorption for each incisor indicated, in decreasing order, a greater resorption for the upper centrals, followed by the upper laterals, lower centrals, and lastly the lower lateral incisors.",
"To describe a compact computed tomographic apparatus (Ortho-CT) for use in dental practice. Ortho-CT is a cone-beam-type of CT apparatus consisting of a multifunctional maxillofacial imaging machine (Scanora, Soredex, Helsinki, Finland) in which the film is replaced with an X-ray imaging intensifier (Hamamatsu Photonics, Hamamatsu, Japan). The region of image reconstruction is a cylinder 32 mm in height and 38 mm in diameter and the voxel is a 0.136-mm cube. Scanning is at 85 kV and 10 mA with a 1 mm Cu filter. The scan time is 17 s comparable with that required for rotational panoramic radiography. A single scan collects 512 sets of projection data through 360 degrees and the image is reconstructed by a personal computer. The time required for image reconstruction is about 10 min. The resolution limit was about 2.0 lp mm-1 and the skin entrance dose 0.62 mGy. Excellent image quality was obtained with a tissue-equivalent skull phantom: roots, periodontal ligament space, lamina dura, and cancellous bone were clearly visualized. Ortho-CT provides three-dimensional images of excellent quality for dental use at a low entrance dose.",
"To investigate the incidence and severity of root resorption during orthodontic treatment by means of cone beam computed tomography (CBCT) and to explore factors affecting orthodontically induced inflammatory root resorption (OIIRR). CBCT examinations were performed on 152 patients with Class I malocclusion. All roots from incisors to first molars were assessed on two or three occasions. At treatment end, 94% of patients had ≥1 root with shortening >1 mm, and 6.6% had ≥1 tooth where it exceeded 4 mm. Among teeth, 56.3% of upper lateral incisors had root shortening >1 mm. Of upper incisors and the palatal root of upper premolars, 2.6% showed root shortenings >4 mm. Slanted surface resorptions of buccal and palatal surfaces were found in 15.1% of upper central and 11.5% of lateral incisors. Monthly root shortening was greater after 6-month control than before. Upper jaw teeth and anterior teeth were significantly associated with the degree of root shortening. Gender, root length at baseline, and treatment duration were not. Practically all patients and up to 91% of all teeth showed some degree of root shortening, but few patients and teeth had root shortenings >4 mm. Slanted root resorption was found on root surfaces that could be evaluated only by a tomographic technique. A CBCT technique can provide more valid and accurate information about root resorption."
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Ivabradine inhibits the hyperpolarization-activated cyclic nucleotide-gated channel in chronic heart failure
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Chronic heart failure (CHF) represents a major cause of hospitalization and death. Recent evidence shows that novel biomarkers such as soluble suppression of tumorigenicity (sST2), growth-differentiation factor-15 (GDF-15), soluble urokinase plasminogen activator receptor (suPAR) and heart-type fatty acid binding protein (H-FABP) are correlated with inflammatory and ischemic responses in CHF patients. In this study we examined the effects of Ivabradine that inhibited the hyperpolarization-activated cyclic nucleotide-gated channel (HCN channel, also called funny current I
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"Loss of cardiomyocytes plays a critical role in the pathogenesis of heart failure. With fewer myocytes, the heart is unable to sustain efficient contraction. Much attention has been focused on understanding mechanisms of cell death in myocytes with the ultimate goal being to reduce the extent of injury and improve function in the failing myocardium. Both necrosis and apoptosis contribute to loss of myocytes, and this loss of cells is a hallmark of cardiac pathologies, including ischemia/reperfusion, myocardial infarction, and heart failure. Apoptosis is a highly regulated process that is activated via death receptors in the plasma membrane or via permeabilization of the mitochondria. Necrosis is generally viewed as an uncontrolled process that leads to mitochondrial swelling, cell rupture, and subsequent inflammation. However, recent studies have uncovered a signaling pathway that mediates regulated necrosis or necroptosis. Mitochondria play an important role in both apoptosis and necrosis, and changes in their morphology can affect the cells' susceptibility to stress. This review focuses on the various modes of cell death in the myocardium and highlights how they contribute to loss of myocytes in response to stress.",
"The ASSOCIATE study investigators have reported that the I(f) current inhibitor, ivabradine, is safe, improves exercise performance, and delays the development of ischemia in patients with chronic stable angina beingtreated with atenolol. ivabradine should be considered in the medical management of symptom-limited patients with angina, when heart rate is suboptimally controlled.",
"In addition to routine clinical laboratory tests (including natriuretic peptides and cardiac troponins), other biomarkers are gaining attention for their utility in heart failure (HF) management. Among them, soluble ST2 (sST2) a novel biomarker integrating inflammation, fibrosis, and cardiac stress has been included in the 2013 ACCF/AHA guideline for additive risk stratification of patients with acute and chronic HF. sST2 is an interleukin-1 (IL-1) receptor family member, is secreted into the circulation and functions as a \"decoy\" receptor for IL-33, inhibiting IL-33/ST2 signaling. Blood concentrations of sST2 are increased in various diseases such as inflammatory diseases and heart diseases and are considered a valuable prognostic marker in both conditions. sST2 lacks disease specificity and, therefore, is not a valuable marker for the diagnosis of HF. In acute and chronic HF, however, sST2 is strongly associated with measures of HF severity and poor outcome. Several studies in patients with HF indicate that serial measurement of sST2 has prognostic value and could have a potential role in future biomarker-directed therapy. In this review, the role of sST2 as a HF biomarker will be discussed, specifically addressing analytical considerations of measuring sST2 as well as the clinical applications of measurement of sST2 for the diagnosis, prognosis and monitoring of acute and chronic HF.",
"Loss of cardiac myocytes in heart failure is thought to occur largely through an apoptotic process. Here we show that heart failure can also be precipitated through myocyte necrosis associated with Ca2+ overload. Inducible transgenic mice with enhanced sarcolemmal L-type Ca2+ channel (LTCC) activity showed progressive myocyte necrosis that led to pump dysfunction and premature death, effects that were dramatically enhanced by acute stimulation of beta-adrenergic receptors. Enhanced Ca2+ influx-induced cellular necrosis and cardiomyopathy was prevented with either LTCC blockers or beta-adrenergic receptor antagonists, demonstrating a proximal relationship among beta-adrenergic receptor function, Ca2+ handling, and heart failure progression through necrotic cell loss. Mechanistically, loss of cyclophilin D, a regulator of the mitochondrial permeability transition pore that underpins necrosis, blocked Ca2+ influx-induced necrosis of myocytes, heart failure, and isoproterenol-induced premature death. In contrast, overexpression of the antiapoptotic factor Bcl-2 was ineffective in mitigating heart failure and death associated with excess Ca2+ influx and acute beta-adrenergic receptor stimulation. This paradigm of mitochondrial- and necrosis-dependent heart failure was also observed in other mouse models of disease, which supports the concept that heart failure is a pleiotropic disorder that involves not only apoptosis, but also necrotic loss of myocytes in association with dysregulated Ca2+ handling and beta-adrenergic receptor signaling.",
"Chronic inflammation underlies a variety of seemingly unrelated conditions including coronary artery disease. The interest in exploring the role of inflammation in heart failure (CHF) arises from earlier observations that circulating pro-inflammatory biomarker levels are elevated in patients with both ischaemic and non-ischaemic cardiomyopathies and correlate with severity of disease and prognosis (McMurray et al. in Eur Heart J 33:1787-1847, 2012; Mosterd and Hoes in Heart 93:1137-1146, 2007; Owan et al. in New Engl J Med 355:251-259, 2006). In acute decompensated HF, pro-inflammatory biomarker levels have been associated with mortality and readmission rates (Cowie et al. in Heart 83:505-510, 2000). Similar to neurohormonal activation and inflammation, production of pro-inflammatory cytokines is a response to stress in an attempt to restore cellular function. However, sustained expression and exposure to cytokines can lead to left ventricular dysfunction, negative inotropic effects, altered cardiac metabolism, myocardial remodelling and HF progression. However, it is unclear whether elevated levels of pro-inflammatory biomarkers, such as high-sensitivity C-reactive protein, signify an ongoing inflammatory process that leads to HF progression, or are merely markers of advanced disease. Beta-blockers, renin-angiotensin-aldosterone axis antagonists, statins and immunosuppressants have been found to decrease the levels of cytokines in small clinical studies of patients with HF (Hobbs et al. in Heart J 28:1128-1134, 2007). However, 'immunomodulatory' approaches applied in the RECOVER, RENAISSANCE, ATTACH, IMAC and ACCLAIM double-blind, placebo-controlled studies had neutral or negative effects on outcomes of patients with HF. In the present review, we focus on the role of inflammation in pathogenesis and progression of the HF, the value of pro-inflammatory cytokines as biomarkers and the potential therapeutic applications of immunomodulation in HF patients.",
"A current paradigm states that monocytes circulate freely and patrol blood vessels but differentiate irreversibly into dendritic cells (DCs) or macrophages upon tissue entry. Here we show that bona fide undifferentiated monocytes reside in the spleen and outnumber their equivalents in circulation. The reservoir monocytes assemble in clusters in the cords of the subcapsular red pulp and are distinct from macrophages and DCs. In response to ischemic myocardial injury, splenic monocytes increase their motility, exit the spleen en masse, accumulate in injured tissue, and participate in wound healing. These observations uncover a role for the spleen as a site for storage and rapid deployment of monocytes and identify splenic monocytes as a resource that the body exploits to regulate inflammation.",
"Chronic heart failure (CHF) is characterized by decreased nitric oxide (NO) bioavailability. In addition, the beneficial NO turns to be deleterious when it reacts with superoxide anion, leading to peroxynitrite formation. Numerous experimental and clinical studies have reported increased production of reactive oxygen species (superoxide, hydrogen peroxide, hydroxyl radical) both in animals and patients with CHF. Moreover, there are indicative data suggesting mechanisms associated with endothelial dysfunction in states of CHF, mainly attributed to decreased NO bioavailability and enhanced inactivation of the latter. Thus, such molecules appear to be potential targets in patients with CHF. These patients are strong candidates to receive a variety of therapeutic agents, some of which have known antioxidant effects. Classic treatment with statins or angiotensin converting enzyme inhibitors has been found to be beneficial in restoring NO and improving myocardial function and structure. Other agents such as sildenafil and b-blockers along with novel agents such as NO synthase transcription enhancers have been proved to be also beneficial, but their use for such a purpose is still controversial. Approaches using more-effective antioxidants or targeting myocardial oxidant-producing enzymes and oxidative or nitrosative stress might be promising strategies in the future.",
"Low-grade inflammation is thought to contribute to the development of cardiovascular disease (CVD), type-2 diabetes mellitus (T2D), cancer and mortality. Biomarkers of inflammation may aid in risk prediction and enable early intervention and prevention of disease. The aim of this study was to investigate whether plasma levels of the inflammatory biomarker soluble urokinase plasminogen activator receptor (suPAR) are predictive of disease and mortality in the general population. This was an observational prospective cohort study. Cohort participants were included from June 1993 to December 1994 and followed until the end of 2006. General adult Caucasian population. The MONICA10 study, a population-based cohort recruited from Copenhagen, Denmark, included 2602 individuals aged 41, 51, 61 or 71 years. Blood samples were analysed for suPAR levels using a commercially available enzyme-linked immunosorbent assay. Risk of cancer (n = 308), CVD (n = 301), T2D (n = 59) and mortality (n = 411) was assessed with a multivariate proportional hazards model using Cox regression. Elevated baseline suPAR level was associated with an increased risk of cancer, CVD, T2D and mortality during follow-up. suPAR was more strongly associated with cancer, CVD and mortality in men than in women, and in younger compared with older individuals. suPAR remained significantly associated with the risk of negative outcome after adjustment for a number of relevant risk factors including C-reactive protein levels. Further validation in ethnic populations other than Caucasians is needed. The stable plasma protein suPAR may be a promising biomarker because of its independent association with incident cancer, CVD, T2D and mortality in the general population.",
"Elevated interleukin-4 (IL-4) levels are associated with cardiac fibrosis in hypertension and heart failure in both patients and experimental animals. We hypothesized that chronically elevated IL-4 induces cardiac fibrosis, resulting in a predisposition of the heart to angiotensin II-induced damage. Wild-type Balb/c (WT, high circulating IL-4) and IL-4-deficient Balb/c mice (IL-4(-/-)) were used. WT mice exhibited cardiac fibrosis (evidenced by an increase in expression of procollagen genes/interstitial collagen fraction), enlarged left ventricle chamber, and declined cardiac function associated with a greater number of mast cells and macrophages in the heart compared with IL-4(-/-). In contrast, IL-4(-/-) mice had normal cardiac architecture/function while showing a 57.9% reduction in heart interstitial collagen compared with WT, despite elevated proinflammatory cytokines in heart tissue. In response to angiotensin II administration, IL-4(-/-) had reduced interstitial myocardial fibrosis and were protected from developing dilated cardiomyopathy, which was seen in WT mice. This was associated with increased macrophage infiltration into the hearts of WT mice, despite a similar degree of hypertension and increased cardiac transforming growth factor-β1 in both groups. In vitro data demonstrated that IL-4 upregulates procollagen genes and stimulates collagen production in mouse cardiac fibroblasts. This process is mediated by signal transducer and activator of transcription 6 signaling pathway via IL-4 receptor alpha. This study not only establishes a causal relationship between IL-4 and cardiac fibrosis/dysfunction, but also reveals a critical role for IL-4 in angiotensin II-induced cardiac damage. IL-4 could serve as an additional target for the treatment of cardiac fibrosis.",
"Necrostatin-1 (Nec-1), a small tryptophan-based molecule, was recently reported to protect the cerebral cortex against ischemia-reperfusion (I/R) injury. We investigated the actions of Nec-1 and its so-called inactive analog, Nec-1i, in the setting of myocardial I/R injury. The actions of Nec-1 and Nec-1i were examined in cultured C2C12 and H9c2 myocytes, cardiomyocytes isolated from male Sprague-Dawley rats, Langendorff isolated perfused C57Bl/6J mouse hearts and an in vivo open-chest C57Bl/6J mouse heart model. Nec-1 at 30 microM and 100 microM (but not 100 microM Nec-1i) reduced peroxide-induced cell death in C2C12 cells from 51.2 +/- 1.1% (control) to 26.3 +/- 2.9% (p < 0.01 vs control) and 17.8 +/- 0.9% (p < 0.001), respectively. With H9c2 cells cell death was also reduced from 73.0 +/- 0.4% (control) to 56.7 +/- 0% (30 microM Nec-1, p < 0.05) and 45.4 +/- 3.3% (100 microM Nec-1, p < 0.01). In the isolated perfused heart Nec-1 (30 microM) reduced infarct size (calculated as a percentage of the risk area) from 48.0 +/- 2.0% (control) to 32.1 +/- 5.4% (p < 0.05). Nec-1i (30 microM) also reduced infarct size (32.9 +/- 5.1%, p < 0.05). In anesthetized C57Bl/6J mice Nec-1 (1.65 mg/kg), given intraperitoneally to coincide with reperfusion following left anterior descending artery ligation (30 min), also reduced infarct size from 45.3 +/- 5.1% (control) to 26.6 +/- 4.0% (p < 0.05), whilst Nec-1i (1.74 mg/kg) was ineffective (37.8 +/- 6.0%). Stimulus-induced opening of the mitochondrial permeability transition pore (MPTP) in rat cardiomyocytes, as reflected by the time until mitochondrial depolarisation, was unaffected by Nec-1 or Nec-1i at 30 muM but increased at 100 muM i.e. 91% (p < 0.05 vs control) and 152% (p < 0.001) for Nec-1 and Nec-1i, respectively. This is the first study to demonstrate that necrostatins inhibit myocardial cell death and reduce infarct size, possibly via a mechanism independent of the MPTP."
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What is the best way to find a review of a book?
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Review of literature.
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"The purpose of this study is to compare bone union rate between autologous iliac bone and local bone graft in patients treated by posterior lumbar interbody fusion (PLIF) using carbon cage for single level interbody fusion. The subjects were 106 patients whose course could be observed for at least 2 years. The diagnosis was lumbar spinal canal stenosis in 46 patients, herniated lumbar disk in 12 patients and degenerative spondylolisthesis in 51 patients. Single interbody PLIF was done using iliac bone graft in 53 patients and local bone graft in 56 patients. Existence of pseudo-arthrosis on X-P (AP and lateral view) was investigated during the same follow up period. No significant differences were found in operation time and blood loss. Significant differences were also not observed in fusion grade at any follow up period or in fusion progression between the two groups. Donor site pain continued for more than 3 months in five cases (9%). The final fusion rate was 96.3 versus 98.3%. Almost the same results in fusion were obtained from both the local bone group and the autologous iliac bone group. Fusion progression was almost the same. Complications at donor sites were seen in 19% of the cases. From the above results, it was concluded that local bone graft is as beneficial as autologous iliac bone graft for PLIF at a single level.",
"Human mesenchymal stem cells are thought to be multipotent cells, which are present in adult marrow, that can replicate as undifferentiated cells and that have the potential to differentiate to lineages of mesenchymal tissues, including bone, cartilage, fat, tendon, muscle, and marrow stroma. Cells that have the characteristics of human mesenchymal stem cells were isolated from marrow aspirates of volunteer donors. These cells displayed a stable phenotype and remained as a monolayer in vitro. These adult stem cells could be induced to differentiate exclusively into the adipocytic, chondrocytic, or osteocytic lineages. Individual stem cells were identified that, when expanded to colonies, retained their multilineage potential.",
"The nonunion rate after posterolateral spinal fusion can be as high as 35%. This has stimulated interest in the development of techniques for enhancing new bone formation, including the addition of bioactive peptides or the use of cell-based therapies, including genetically modified cells. In previous studies we have demonstrated that exposing autologous, marrow-derived osteoprogenitor cells to a recombinant human bone morphogenetic protein-6 (rhBMP-6) containing extracellular matrix induces osteoblastic differentiation, and that these cells are capable of increasing new bone formation. Growth of autologous cells on a synthetic rhBMP-6 containing matrix yields a population of stimulated osteoprogenitor cells, without the expense of adding large amounts of rhBMP-6 directly, or the risks inherent in the use of genetically altered cells. This study was performed to evaluate the potential of rhBMP-6 stimulated osteoprogenitor cells (stOPC) to enhance the rate and strength of posterolateral spinal fusion. Prospective in vivo animal study Radiographic evidence of spinal fusion, biomechanical testing of explanted spines, histological analysis of new bone formation Single-level posterolateral spinal arthrodeses were performed in 69 New Zealand white rabbits. Autologous marrow stem cells were concentrated and then plated on an rhBMP-6-rich extracellular matrix synthesized by genetically engineered mouse C3H10T1/2 cells. Animals in Groups I (n=18) and II (n=18) received autografts of 30M and 60M rhBMP-6 stOPCs in guanidine extracted demineralized bone matrix (gDBM), respectively, whereas those in Group III (n=13) received iliac crest bone graft (ICBG). Those in Group IV (n=10) received gDBM, and those in Group V (n=10) underwent decortication only. Assessment of fusion was made with serial radiographs, manual palpation of the explanted spines, and biomechanical testing. The fusion masses from two animals each in Groups I, II, and IV were evaluated histologically. Fifty-three animals were available for analysis at the conclusion of the study. In these animals, the arthrodesis rate was significantly higher after treatment with rhBMP-6 stOPCs (77% for both Groups I and II by palpation) than ICBG, gDBM, or decortication alone (Group III=55%, IV=20% and V=0%, respectively). Similarly, the peak loads to failure of the fusion masses in Groups I and II (212.5+/-37.8 N and 234.6+/-45.7 N) were significantly greater than the corresponding values in the other groups (Group III=155.9+/-36.4N, Group IV=132.7+/-59.9N, and Group V=92.8+/-18.4N), though when only the fused specimens in Groups I, II, and III were compared, only Group II was significantly different than Group III (234.6+/-45.7N and 155.9+/-36.4N, respectively). The fusion masses in the rhBMP-6 stOPC-treated animals were typified by a thin, fusiform cortical shell, newly formed trabecular bone emanating from the decorticated transverse processes, and residual unremodeled gDBM carrier particles. The fusion masses in the gDBM treated bones were morphologically similar, though they contained less newly formed bone. The use of rhBMP-6 stOPCs in a carrier of gDBM significantly enhanced the rate and strength of single-level posterolateral spinal arthrodeses in the New Zealand white rabbit, compared with ICBG, gDBM, and decortication alone. Our results confirm that the stimulation of marrow-derived osteoprogenitor cells by growing them on a rhBMP-6 containing extracellular matrix is feasible. Further investigation is warranted to determine the relative contribution of rhBMP-6 stimulation and the number of cells implanted, as well as strategies for optimizing the technique for clinical application.",
"This is a retrospective review of 25 patients with severe lumbar nerve root compression undergoing multilevel anterior retroperitoneal lumbar interbody fusion and posterior instrumentation for deformity. The objective is to analyze the outcomes and clinical results from anterior interbody fusions performed through a lateral approach and compare these with traditional surgical procedures. A consecutive series of 25 patients (78 extreme lateral interbody fusion [XLIF] levels) was identified to illustrate the primary advantages of XLIF in correcting the most extreme of the 3-dimensional deformities that fulfilled the following criteria: (1) a minimum of 40° of scoliosis; (2) 2 or more levels of translation, anterior spondylolisthesis, and lateral subluxation (subluxation in 2 planes), causing symptomatic neurogenic claudication and severe spinal stenosis; and (3) lumbar hypokyphosis or flat-back syndrome. In addition, the majority had trunks that were out of balance (central sacral vertical line ≥2 cm from vertical plumb line) or had sagittal imbalance, defined by a distance between the sagittal vertical line and S1 of greater than 3 cm. There were 25 patients who had severe enough deformities fulfilling these criteria that required supplementation of the lateral XLIF with posterior osteotomies and pedicle screw instrumentation. In our database, with a mean follow-up of 24 months, 85% of patients showed evidence of solid arthrodesis and no subsidence on computed tomography and flexion/extension radiographs. The complication rate remained low, with a perioperative rate of 2.4% and postoperative rate of 12.2%. The lateral listhesis and anterior spondylolisthetic subluxation were anatomically reduced with minimally invasive XLIF. The main finding in these 25 cases was our isolation of the major indication for supplemental posterior surgery: truncal decompensation in patients who are out of balance by 2 cm or more, in whom posterior spinal osteotomies and segmental pedicle screw instrumentation were required at follow up. No patients were out of sagittal balance (sagittal vertical line <3 cm from S1) postoperatively. Segmental instrumentation with osteotomies was also more effective for restoration of physiologic lumbar lordosis compared with anterior stand-alone procedures. This retrospective study supports the finding that clinical outcomes (coronal/sagittal alignment) improve postoperatively after minimally invasive surgery with multilevel XLIF procedures and are improved compared with larger extensile thoracoabdominal anterior scoliosis procedures.",
"We used computed tomography and the rabbit model to seek an explanation for the biomechanical superiority of recombinant human bone morphogenetic protein-2 (rhBMP-2) as compared with autogenous iliac bone in lumbar intertransverse process fusions, i.e., the rhBMP-2 fusions demonstrated significantly higher strength and stiffness. The results show that the fusion masses using rhBMP-2 have higher volume, and higher minimum contact area of fusion mass attachment to the transverse process. For both bone graft materials there was a correlation between site of failure and the fusion mass quadrant that contained the minimum contact area of attachment to the transverse process. The ideal graft material would be one that produced strong, mature, early fusions that failed along their length at random positions, rather than failing with high frequency at the transverse process. The fusions using rhBMP-2 were nearer to the ideal than those using autograft: These were stronger, more mature, and only 6 of 9 rhBMP-2 failed in the quadrant that contained the minimum contact area of attachment to the transverse process, as opposed to 11 of 12 for autograft."
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Comparison of RAD-Seq and microsatellite data for phylogeographic inferences
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The widespread adoption of RAD-Seq data in phylogeography means genealogical relationships previously evaluated using relatively few genetic markers can now be addressed with thousands of loci. One challenge, however, is that RAD-Seq generates complete genotypes for only a small subset of loci or individuals. Simulations indicate that loci with missing data can produce biased estimates of key population genetic parameters, although the influence of such biases in empirical studies is not well understood. Here we compare microsatellite data (8 loci) and RAD-Seq data (six datasets ranging from 239 to 25,198 loci) from red mangroves (Rhizophora mangle) in Florida to evaluate how different levels of data filtering influence phylogeographic inferences. For all datasets, we calculated population genetic statistics and evaluated population structure, and for RAD-Seq datasets, we additionally examined population structure using coalescence. We found higher F
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[
"We characterize and extend a highly efficient method for constructing shotgun fragment libraries in which transposase catalyzes in vitro DNA fragmentation and adaptor incorporation simultaneously. We apply this method to sequencing a human genome and find that coverage biases are comparable to those of conventional protocols. We also extend its capabilities by developing protocols for sub-nanogram library construction, exome capture from 50 ng of input DNA, PCR-free and colony PCR library construction, and 96-plex sample indexing.",
"Next-generation sequencing technologies are revolutionizing the field of evolutionary biology, opening the possibility for genetic analysis at scales not previously possible. Research in population genetics, quantitative trait mapping, comparative genomics, and phylogeography that was unthinkable even a few years ago is now possible. More importantly, these next-generation sequencing studies can be performed in organisms for which few genomic resources presently exist. To speed this revolution in evolutionary genetics, we have developed Restriction site Associated DNA (RAD) genotyping, a method that uses Illumina next-generation sequencing to simultaneously discover and score tens to hundreds of thousands of single-nucleotide polymorphism (SNP) markers in hundreds of individuals for minimal investment of resources. In this chapter, we describe the core RAD-seq protocol, which can be modified to suit a diversity of evolutionary genetic questions. In addition, we discuss bioinformatic considerations that arise from unique aspects of next-generation sequencing data as compared to traditional marker-based approaches, and we outline some general analytical approaches for RAD-seq and similar data. Despite considerable progress, the development of analytical tools remains in its infancy, and further work is needed to fully quantify sampling variance and biases in these data types.",
"Restriction site-associated DNA Sequencing (RAD-Seq) is an economical and efficient method for SNP discovery and genotyping. As with other sequencing-by-synthesis methods, RAD-Seq produces stochastic count data and requires sensitive analysis to develop or genotype markers accurately. We show that there are several sources of bias specific to RAD-Seq that are not explicitly addressed by current genotyping tools, namely restriction fragment bias, restriction site heterozygosity and PCR GC content bias. We explore the performance of existing analysis tools given these biases and discuss approaches to limiting or handling biases in RAD-Seq data. While these biases need to be taken seriously, we believe RAD loci affected by them can be excluded or processed with relative ease in most cases and that most RAD loci will be accurately genotyped by existing tools.",
"Microsatellites have been popular molecular markers ever since their advent in the late eighties. Despite growing competition from new genotyping and sequencing techniques, the use of these versatile and cost-effective markers continues to increase, boosted by successive technical advances. First, methods for multiplexing PCR have considerably improved over the last years, thereby decreasing genotyping costs and increasing throughput. Second, next-generation sequencing technologies allow the identification of large numbers of microsatellite loci at reduced cost in non-model species. As a consequence, more stringent selection of loci is possible, thereby further enhancing multiplex quality and efficiency. However, current practices are lagging behind. By surveying recently published population genetic studies relying on simple sequence repeats, we show that more than half of the studies lack appropriate quality controls and do not make use of multiplex PCR. To make the most of the latest technical developments, we outline the need for a well-established strategy including standardized high-throughput bench protocols and specific bioinformatic tools, from primer design to allele calling."
] |
The cell division inhibition gene sfiC is part of the excisable element e14
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The cell division inhibition gene sfiC and the excisable element e14, both associated with the SOS response in Escherichia coli, are located at 25 min on the E. coli map. Blotting with a fragment of e14 DNA showed a strict correlation between the presence of e14 and the sfiC+ genotype. Introduction of only e14 into a recA- sfiC- strain made the strain sfiC+. These results show that the sfiC gene is part of e14.
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[
"The gene product of bacteriophage Mu gin catalyzes a 3,000-base-pair inversion in the DNA of the phage, thus changing its host range. In some strains of Escherichia coli there is a function that can complement Mu gin mutations. This function (pin) was cloned and shown to catalyze an inversion of 1,800 base pairs in the adjacent E. coli DNA (P region). pin- derivatives carry the P region frozen in the (+) or (-) orientation. The function of the switch is not yet clear. The sequences of gin and pin were determined; they exhibit 70% homology. The sequences around the recombination sites of Gin and Pin are also largely homologous; a consensus sequence is derived for the recombination sites of Gin and Pin, and of Hin in Salmonella typhimurium. The amino acid sequences of Gin, Pin, Hin, and TnpR are compared, and the evolutionary relationship between these prokaryotic site-specific recombination systems is discussed.",
"We have previously described a gene, secA, which may code for a component of the secretion machinery of E. coli. Temperature-sensitive mutations in this gene lead to the cytoplasmic accumulation of precursors to a number of secreted proteins. In this paper, we describe the use of antibody to the SecA protein to characterize the cellular location and regulation of the protein. The antibody was elicited in response to a SecA-LacZ hybrid protein, produced by a strain carrying a secA-lacZ gene fusion. The secA gene product is a 92 kd polypeptide that is present in small amounts in the cell and that fractionates as a peripheral cytoplasmic membrane protein. The synthesis of the SecA protein is greatly derepressed (at least tenfold) when secretion in E. coli is blocked either in a secAts mutant or in the presence of a MalE-LacZ hybrid protein. We suggest that components of the secretion machinery of E. coli, such as the SecA protein, may be regulated in response to the secretion needs of the cell. When suppression of a secAam mutant is eliminated, leading to the absence of SecA protein, the synthesis of maltose-binding protein is greatly reduced. These results support a mechanism in which secretion and translation are coupled.",
"Induction of the SOS response in Escherichia coli by DNA-damaging treatments results in the synthesis of the SulA polypeptide, and this is sufficient to cause the resulting inhibition of cell division. Mutations at either sulA (sfiA) or sulB (sfiB) suppress this division inhibition. The SulB protein is identical to FtsZ, a protein required for normal division in E. coli. In the presence of FtsZ, the half-life of SulA synthesized in maxicells is approximately 12 min. In contrast, in the absence of FtsZ or in the presence of a mutant form of FtsZ (SulB114) that prevents division inhibition in vivo, SulA is extremely unstable with a half-life of only 3 min. Both FtsZ and SulA are isolated with the inner membrane of E. coli maxicells in the presence of MgCl2. We propose that the SulA inhibitor interacts directly with FtsZ in vivo to block the essential division function of this protein."
] |
Integrative Systems Biology Study of Diet-Induced Hepatic Insulin Resistance
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Obesity is a major human health crisis that promotes insulin resistance and, ultimately, type 2 diabetes. The molecular mechanisms that mediate this response occur across many highly complex biological regulatory levels that are incompletely understood. Here, we present a comprehensive molecular systems biology study of hepatic responses to high-fat feeding in mice. We interrogated diet-induced epigenomic, transcriptomic, proteomic, and metabolomic alterations using high-throughput omic methods and used a network modeling approach to integrate these diverse molecular signals. Our model indicated that disruption of hepatic architecture and enhanced hepatocyte apoptosis are among the numerous biological processes that contribute to early liver dysfunction and low-grade inflammation during the development of diet-induced metabolic syndrome. We validated these model findings with additional experiments on mouse liver sections. In total, we present an integrative systems biology study of diet-induced hepatic insulin resistance that uncovered molecular features promoting the development and maintenance of metabolic disease.
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[
"High-throughput genome-wide molecular assays, which probe cellular networks from different perspectives, have become central to molecular biology. Probabilistic graphical models are useful for extracting meaningful biological insights from the resulting data sets. These models provide a concise representation of complex cellular networks by composing simpler submodels. Procedures based on well-understood principles for inferring such models from data facilitate a model-based methodology for analysis and discovery. This methodology and its capabilities are illustrated by several recent applications to gene expression data.",
"We develop a new framework for inferring models of transcriptional regulation. The models, which we call physical network models, are annotated molecular interaction graphs. The attributes in the model correspond to verifiable properties of the underlying biological system such as the existence of protein-protein and protein-DNA interactions, the directionality of signal transduction in protein-protein interactions, as well as signs of the immediate effects of these interactions. Possible configurations of these variables are constrained by the available data sources. Some of the data sources, such as factor-binding data, involve measurements that are directly tied to the variables in the model. Other sources, such as gene knock-outs, are functional in nature and provide only indirect evidence about the variables. We associate each observed knock-out effect in the deletion mutant data with a set of causal paths (molecular cascades) that could in principle explain the effect, resulting in aggregate constraints about the physical variables in the model. The most likely settings of all the variables, specifying the most likely graph annotations, are found by a recursive application of the max-product algorithm. By testing our approach on datasets related to the pheromone response pathway in S. cerevisiae, we demonstrate that the resulting model is consistent with previous studies about the pathway. Moreover, we successfully predict gene knock-out effects with a high degree of accuracy in a cross-validation setting. When applying this approach genome-wide, we extract submodels consistent with previous studies. The approach can be readily extended to other data sources or to facilitate automated experimental design.",
"The mechanism(s) and site(s) of the insulin resistance were examined in nine normal-weight noninsulin-dependent diabetic (NIDD) subjects. The euglycemic insulin clamp technique (insulin concentration approximately 100 microU/ml) was employed in combination with hepatic and femoral venous catheterization and measurement of endogenous glucose production using infusion of tritiated glucose. Total body glucose metabolism in the NIDD subjects (4.37 +/- 0.45 mg/kg per min) was 38% (P less than 0.01) lower than in controls (7.04 +/- 0.63 mg/kg per min). Quantitatively, the most important site of the insulin resistance was found to be in peripheral tissues. Leg glucose uptake in the diabetic group was reduced by 45% as compared with that in controls (6.0 +/- 0.2 vs. 11.0 +/- 0.1 mg/kg leg wt per min; P less than 0.01). A strong positive correlation was observed between leg and total body glucose uptake (r = 0.70, P less than 0.001). Assuming that muscle is the primary leg tissue responsible for glucose uptake, it could be estimated that 90 and 87% of the infused glucose was disposed of by peripheral tissues in the control and NIDD subjects, respectively. Net splanchnic glucose balance during insulin stimulation was slightly more positive in the control than in the diabetic subjects (0.31 +/- 0.10 vs. 0.05 +/- 0.19 mg/kg per min; P less than 0.07). The difference (0.26 mg/kg per min) in net splanchnic glucose balance in NIDD represented only 10% of the reduction (2.67 mg/kg per min) in total body glucose uptake in the NIDD group and thus contributed very little to the insulin resistance. The results emphasize the importance of the peripheral tissues in the disposal of infused glucose and indicate that muscle is the most important site of the insulin resistance in NIDD.",
"A fundamental challenge in human health is the identification of disease-causing genes. Recently, several studies have tackled this challenge via a network-based approach, motivated by the observation that genes causing the same or similar diseases tend to lie close to one another in a network of protein-protein or functional interactions. However, most of these approaches use only local network information in the inference process and are restricted to inferring single gene associations. Here, we provide a global, network-based method for prioritizing disease genes and inferring protein complex associations, which we call PRINCE. The method is based on formulating constraints on the prioritization function that relate to its smoothness over the network and usage of prior information. We exploit this function to predict not only genes but also protein complex associations with a disease of interest. We test our method on gene-disease association data, evaluating both the prioritization achieved and the protein complexes inferred. We show that our method outperforms extant approaches in both tasks. Using data on 1,369 diseases from the OMIM knowledgebase, our method is able (in a cross validation setting) to rank the true causal gene first for 34% of the diseases, and infer 139 disease-related complexes that are highly coherent in terms of the function, expression and conservation of their member proteins. Importantly, we apply our method to study three multi-factorial diseases for which some causal genes have been found already: prostate cancer, alzheimer and type 2 diabetes mellitus. PRINCE's predictions for these diseases highly match the known literature, suggesting several novel causal genes and protein complexes for further investigation.",
"Impaired insulin-mediated suppression of hepatic glucose production (HGP) plays a major role in the pathogenesis of type 2 diabetes (T2D), yet the molecular mechanism by which this occurs remains unknown. Using a novel in vivo metabolomics approach, we show that the major mechanism by which insulin suppresses HGP is through reductions in hepatic acetyl CoA by suppression of lipolysis in white adipose tissue (WAT) leading to reductions in pyruvate carboxylase flux. This mechanism was confirmed in mice and rats with genetic ablation of insulin signaling and mice lacking adipose triglyceride lipase. Insulin's ability to suppress hepatic acetyl CoA, PC activity, and lipolysis was lost in high-fat-fed rats, a phenomenon reversible by IL-6 neutralization and inducible by IL-6 infusion. Taken together, these data identify WAT-derived hepatic acetyl CoA as the main regulator of HGP by insulin and link it to inflammation-induced hepatic insulin resistance associated with obesity and T2D.",
"In the first part of our review (see Pharmacol Rev 2002;54:129-158), we discussed the basic principles of gene transcription and the complex interactions within the network of hepatocyte nuclear factors, coactivators, ligands, and corepressors in targeted liver-specific gene expression. Now we summarize the role of basic region/leucine zipper protein family members and particularly the albumin D site-binding protein (DBP) and the CAAT/enhancer-binding proteins (C/EBPs) for their importance in liver-specific gene expression and their role in liver function and development. Specifically, regulatory networks and molecular interactions were examined in detail, and the experimental findings summarized in this review point to pivotal roles of DBP and C/EBPs in cell cycle control, carcinogenesis, circadian gene regulation, liver regeneration, apoptosis, and liver-specific gene regulation. These regulatory proteins are therefore of great importance in liver physiology, liver disease, and liver development. Furthermore, interpretation of the vast data generated by novel genomic platform technologies requires a thorough understanding of regulatory networks and particularly the hierarchies that govern transcription and translation of proteins as well as intracellular protein modifications. Thus, this review aims to stimulate discussions on directions of future research and particularly the identification of molecular targets for pharmacological intervention of liver disease.",
"The tyrosine kinase c-Met promotes the formation and malignant progression of multiple cancers. It is well known that c-Met hyperactivation increases tumorigenicity and tumor cell resistance to DNA damaging agents, properties associated with tumor-initiating stem cells. However, a link between c-Met signaling and the formation and/or maintenance of neoplastic stem cells has not been previously identified. Here, we show that c-Met is activated and functional in glioblastoma (GBM) neurospheres enriched for glioblastoma tumor-initiating stem cells and that c-Met expression/function correlates with stem cell marker expression and the neoplastic stem cell phenotype in glioblastoma neurospheres and clinical glioblastoma specimens. c-Met activation was found to induce the expression of reprogramming transcription factors (RFs) known to support embryonic stem cells and induce differentiated cells to form pluripotent stem (iPS) cells, and c-Met activation counteracted the effects of forced differentiation in glioblastoma neurospheres. Expression of the reprogramming transcription factor Nanog by glioblastoma cells is shown to mediate the ability of c-Met to induce the stem cell characteristics of neurosphere formation and neurosphere cell self-renewal. These findings show that c-Met enhances the population of glioblastoma stem cells (GBM SCs) via a mechanism requiring Nanog and potentially other c-Met-responsive reprogramming transcription factors."
] |
Dental implants in patients with Sjögren's syndrome
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The Sjögren's syndrome (SS) is a chronic autoimmune disease that affects salivation and consequently the health of oral tissues. The aim of this systematic review was to investigate the implant survival rate, marginal bone loss (MBL) and biological complications of dental implants in SS patients.
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[
"It has been suggested that some local and systemic factors could be contraindications to dental implant treatment. The objective of this paper was to evaluate whether success and survival rates of dental implants are reduced in the medically compromised patient. An extensive literature search was conducted using PubMed/Medline, Scopus, Scirus and Cochrane databases up to November 8, 2012. There are very few absolute medical contraindications to dental implant treatment, although a number of conditions may increase the risk of treatment failure or complications. The degree of systemic disease-control may be far more important that the nature of the disorder itself, and individualized medical control should be established prior to implant therapy, since in many of these patients the quality of life and functional benefits from dental implants may outweigh any risks.",
"Preparing a review entails many judgments. The focus of the review must be decided. Studies that are relevant to the focus of the review must be identified, selected for inclusion and critically appraised. Information must be collected and synthesised from the relevant studies, and conclusions must be drawn. Checklists can help prevent important errors in this process. Reviewers, editors, content experts, and users of reviews all have a role to play in improving the quality of published reviews and promoting the appropriate use of reviews by decisionmakers. It is essential that both providers and users appraise the validity of review articles.",
"The aims of this investigation were: (i) to study a group of dry mouth Sjögren's syndrome (SS) patients comprising individuals with pathological and non-pathological amounts of rest saliva and (ii) to compare these two categories of SS patients with a sex- and age-matched control group with respect to their periodontal and dental status. Thirty-three dry mouth patients and 33 sex- and age-matched patients, referred to the same private dental clinic in southern Norway, were examined for rest and stimulated saliva, as well as their dental and periodontal status. All patients were referred to the local hospital for blood and urine examinations. The dry mouth SS patients were all of the secondary type. Volumes of rest and stimulated saliva were significantly lower in the low saliva SS group compared with the high saliva SS group; the values for immunoglobulin G (IgG) and IgA were similarly lower for the low saliva group, but not for IgM which was significantly higher. The two SS subgroups and their controls were compared for the volume of rest and stimulated saliva, which showed a statistically significant lower volumes for the low saliva SS group compared with the control group. None of the subgroups and their controls differed concerning filled or missing teeth, but the total SS group revealed significantly higher number of missing teeth. The periodontal and dental status did not show any statistically significant differences except for a few scattered higher periodontal level losses of attachment in the SS subgroups. The blood and urine analyses showed statistically significant higher values for sedimentation rate, white blood cell count and haemoglobin in the SS low saliva group compared with the control group while anti-streptolysin was lower. In the high saliva SS group only sedimentation rate and white cell count were higher compared with the control. The conclusions is SS patients do not have an increased risk for developing periodontitis.",
"Our objective was to develop an instrument to assess the methodological quality of systematic reviews, building upon previous tools, empirical evidence and expert consensus. A 37-item assessment tool was formed by combining 1) the enhanced Overview Quality Assessment Questionnaire (OQAQ), 2) a checklist created by Sacks, and 3) three additional items recently judged to be of methodological importance. This tool was applied to 99 paper-based and 52 electronic systematic reviews. Exploratory factor analysis was used to identify underlying components. The results were considered by methodological experts using a nominal group technique aimed at item reduction and design of an assessment tool with face and content validity. The factor analysis identified 11 components. From each component, one item was selected by the nominal group. The resulting instrument was judged to have face and content validity. A measurement tool for the 'assessment of multiple systematic reviews' (AMSTAR) was developed. The tool consists of 11 items and has good face and content validity for measuring the methodological quality of systematic reviews. Additional studies are needed with a focus on the reproducibility and construct validity of AMSTAR, before strong recommendations can be made on its use.",
"Issues related to peri-implant disease were discussed. It was observed that the most common lesions that occur, i.e. peri-implant mucositis and peri-implantitis are caused by bacteria. While the lesion of peri-implant mucositis resides in the soft tissues, peri-implantitis also affects the supporting bone. Peri-implant mucositis occurs in about 80% of subjects (50% of sites) restored with implants, and peri-implantitis in between 28% and 56% of subjects (12-40% of sites). A number of risk indicators were identified including (i) poor oral hygiene, (ii) a history of periodontitis, (iii) diabetes and (iv) smoking. It was concluded that the treatment of peri-implant disease must include anti-infective measures. With respect to peri-implant mucositis, it appeared that non-surgical mechanical therapy caused the reduction in inflammation (bleeding on probing) but also that the adjunctive use of antimicrobial mouthrinses had a positive effect. It was agreed that the outcome of non-surgical treatment of peri-implantitis was unpredictable. The primary objective of surgical treatment in peri-implantitis is to get access to the implant surface for debridement and decontamination in order to achieve resolution of the inflammatory lesion. There was limited evidence that such treatment with the adjunctive use of systemic antibiotics could resolve a number of peri-implantitis lesions. There was no evidence that so-called regenerative procedures had additional beneficial effects on treatment outcome."
] |
Airway and cardiovascular effects of bucindolol in mild to moderately severe asthma.
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The airway and cardiovascular effects of separate single oral doses of 50, 100 and 200 mg of bucindolol were compared to those of placebo in a double-blind trial in 16 patients with mild to moderately severe asthma. Heart rate (HR), blood pressure (BP), forced vital capacity (FVC), forced expired volume in one second (FEV1), maximum expiratory flow at 50% of vital capacity (FEF50) and maximum expiratory flow at 75% of expired vital capacity (FEF75) were measured before and at intervals for 4h, when salbutamol (200 micrograms) was inhaled and the measurements repeated 15 min later. There was an interval of at least 4 days between each drug treatment day. Four of the 16 patients developed clinically significant bronchoconstriction with 50 mg (3) or 100 mg (1) of bucindolol and were withdrawn from the study. The remaining patients showed impaired bronchodilator response to salbutamol for each bucindolol dose as compared to placebo. No significant BP or HR effects were measured. Two patients withdrew because of circumstances unrelated to bucindolol induced bronchoconstriction. The development of bucindolol induced bronchoconstriction in this group of mild to moderate asthmatics was not predicted by the level of baseline pulmonary function, or the level of histamine responsiveness. However, there was a weak relationship between bucindolol induced bronchoconstriction and salbutamol induced bronchodilation. There are no definitive asthmatic characteristic to predict the likelihood of significant bucindolol induced bronchoconstriction in this asthmatic population.
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[
"1 Bronchial smooth muscle, skeletal muscle and cardiac beta-adrenoceptor antagonism have been compared in twelve asthmatic patients after three beta-adrenoceptor antagonists at two dose levels. The non-selective antagonist propranolol (40 and 160 mg), the non-selective antagonist with partial agonist activity pindolol (5 and 20 mg) and the beta 1-selective antagonist atenolol (50 and 200 mg) were studied on separate occasions. 2 Six placebo days were used in this double-blind crossover study to allow interpretation of individual as well as group results. 3 Bronchial smooth muscle effects were assessed by resting spirometry, histamine inhalation test and spirometric response to inhaled fenoterol. Skeletal muscle effects were assessed by resting tremor and fenoterol induced tremor. 4 Cardiac beta-adrenoceptor antagonism was assessed by measuring the effect on resting heart rate and on maximum heart rate in a standard exercise test. 5 Pindolol tended to cause least change from placebo in resting spirometry, caused significant tremor response, inhibited the fenoterol airway response, and tended to protect against inhaled histamine. 6 Atenolol 60 mg was the only drug to allow a fenoterol airway response similar to placebo. Atenolol increased the inhaled histamine responsiveness. 7 Propranolol 160 mg caused the most reduction in spirometry but also tended to cause the maximum reduction in exercise heart rate. Propranolol caused increased inhaled histamine responsiveness. 8 Initial sensitivity to inhaled histamine did not necessarily predict significant reduction in an asthmatics' spirometry by a beta-adrenoceptor antagonist. The effect of a beta-adrenoceptor antagonist on histamine responsiveness does not correspond to its effect on inhaled beta 2-adrenoceptor agonist responsiveness.",
"We studied the comparative effects of beta-adrenergic blockade with propranolol (PROP) and bucindolol (BUC), a beta-adrenergic agonist having both alpha-adrenergic blocking properties and intrinsic sympathomimetic activity (ISA) on airway and cardiovascular responses, in 38 mongrel dogs in situ. Intravenous infusion of 0.6 mg/kg + 6 micrograms/kg/min BUC and 2.0 mg/kg + 20 micrograms/kg/min PROP caused identical shifts in the isoproterenol (ISO) EC50 for chronotropic and hypotensive arterial blood pressure responses. After PROP administration, resting heart rate (HR) decreased from 188 +/- 15 to 142 +/- 12 beats/min (p less than 0.02); BUC caused no decrease in HR. In contrast, the effects of BUC and PROP on mean arterial blood pressure response to ISO were similar. No change in bronchomotor tone was observed after bolus injection of either BUC or PROP. Beta-Adrenergic relaxation to ISO and alpha-adrenergic contraction to norepinephrine (NE) were studied simultaneously in tracheal and bronchial airways using chronotropically equivalent beta-adrenoceptor blocking doses of PROP and BUC. Comparable inhibition of ISO-induced airway relaxation after contraction with 120 micrograms/kg/min i.v. serotonin was demonstrated in both PROP (n = 5) and BUC (n = 5) groups (p less than 0.01 for doses greater than 5 X 10(-11) mol/kg). Similarly, both BUC (n = 5) and PROP (n = 5) blocked beta-adrenergic relaxation and caused identical alpha-adrenergic airway contraction to intravenous NE. We conclude that the ISA of the beta-adrenergic blocking drug BUC can be demonstrated on the spontaneous rate of the heart but not on the activity of bronchial smooth muscle. BUC neither augments ISO-induced relaxation nor inhibits NE-induced contraction of airways after effective chronotropic blockade.",
"In a double-blind, within-patient, randomized study, 12 mild asthmatics were given single oral doses of propranolol (80 mg), metoprolol (100 mg), timolol (10 mg), or placebo. Resting heart rate and forced expiratory volume in one sec (FEV1) were measured before and 90 min after treatment. Nonspecific bronchial reactivity was measured by inhaled histamine at 90 min. Following each active drug, resting heart rate changed to a similar extent and to a greater degree than after placebo (p less than 0.01). Changes in FEV1 were small and not different from those after placebo. In contrast, after each active drug, bronchial reactivity increased more than after placebo. The degree of reactivity with each active drug was similar but the differences from corresponding placebo values were significant (p less than 0.05). We conclude that, in mild asthmatics, nonspecific bronchial reactivity is a more sensitive index of airway effects than resting FEV1. Moreover, in the context of this study, since the beta-blockers were given in doses likely to induce equivalent cardiac beta-blockade, there is no evidence to suggest that any one of them is more \"cardioselective\" than the others.",
"A rapid, specific, high-pressure liquid chromatographic determination of atenolol in plasma and urine was developed. This method employs the high sensitivity of fluorescence detection together with selective extraction and reversed-phase chromatography to measure concentrations as low as 20 ng of drug/ml of plasma with a coefficient of variation of 3.91%. The assay is specific enough to be valid in the presence of plasma and urine substances. The detection limit (i.e., three times baseline noise) is 3 ng/ml."
] |
Nanotoxoids: a novel class of nanoparticulate vaccines
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As nanoparticles exhibit unique properties attractive for vaccine development, they have been progressively implemented as antigen delivery platforms and immune potentiators. Recently, cell membrane-coated nanoparticles have provided a novel approach for intercepting and neutralizing bacterial toxins by leveraging their natural affinity to cellular membranes. Such toxin-nanoparticle assemblies, termed nanotoxoids, allow rapid loading of different types of toxins and have been investigated for their ability to effectively confer protection against bacterial infection. This topical review will cover the current progress in antibacterial vaccine nanoformulations and highlight the nanotoxoid platform as a novel class of nanoparticulate vaccine. We aim to provide insights into the potential of nanotoxoids as a platform that is facile to implement and can be broadly applied to help address the rising threat of super pathogens.
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[
"In three experiments subcutaneous vaccination of calves with adjuvanted bacteria-free leukotoxic culture supernatant from log phase cultures of Pasteurella haemolytica A1 (toxin 1) was shown to induce some protection against intrabronchial challenge with live P. haemolytica A1. This toxin 1 vaccine was as effective as a whole cell bacterin in stimulating agglutinating antibody to P. haemolytica. Induction of leukotoxin neutralizing activity was variable; in some cases vaccination only primed the animal to produce an anamnestic response after challenge, whereas in other instances antitoxic activity increased in response to immunization. Two doses of vaccine were shown to be more effective than a single immunization. Vaccination with leukotoxic culture supernatant from the nonpathogenic P. haemolytica serotype 11 was as effective as vaccination with toxin 1 in stimulating antitoxic activity but was not protective. This implies that both serospecific agglutinating activity and an antitoxic response are needed for immunity.",
"Genetically attenuated microorganisms, including pathogenic and commensal bacteria, can be engineered to carry and deliver heterologous antigens to elicit host immunity against both the vector as well as the pathogen from which the donor gene is derived. These live attenuated bacterial vectors have been given much attention due to their capacity to induce a broad range of immune responses including localized mucosal, as well as systemic humoral and/or cell-mediated immunity. In addition, the unique tumor-homing characteristics of these bacterial vectors has also been exploited for alternative anti-tumor vaccines and therapies. In such approach, tumor-associated antigen, immunostimulatory molecules, anti-tumor drugs, or nucleotides (DNA or RNA) are delivered. Different potential vectors are appropriate for specific applications, depending on their pathogenic routes. In this review, we survey and summarize the main features of the different types of live bacterial vectors and discussed the clinical applications in the field of vaccinology. In addition, different approaches for using live attenuated bacterial vectors for anti-cancer therapy is discussed, and some promising pre-clinical and clinical studies in this field are outlined.",
"A sterile culture supernatant from each of the 12 recognized serotypes of Pasteurella haemolytica was toxic to bovine alveolar macrophages when assayed by 51Cr release. Types appeared to differ in their ability to liberate cytotoxin, although this may have reflected strain variation rather than serotype-related differences. Toxicity was partially neutralized by type-specific rabbit antisera, with neutralization of the homologous toxin being more effective than that of the heterologous serotype.",
"In 3 experiments, calves were vaccinated by intrabronchial or subcutaneous injection of formalinized Pasteurella haemolytica. Immunization was evaluated by assessing the clinical and pathologic responses to pulmonary challenge exposure with live homologous bacteria. Serum and bronchoalveolar washings were titrated for antibody by indirect (antiglobulin) bacterial agglutination. Response to challenge exposure was determined by increased rectal temperature and faster respiratory rate. In all experiments, the most obvious clinical change occurred in challenge-exposed calves which had been vaccinated by the subcutaneous injection of killed P haemolytica with added adjuvant. Also, macroscopic pulmonic lesions were recorded most frequently in calves vaccinated by this route. In all instances, immunization resulted in elevated anti-P haemolytica titers both in lung and serum.",
"Group A Streptococcus (Streptococcus pyogenes), group B Streptococcus (Streptococcus agalactiae) and Streptococcus pneumoniae (pneumococcus) are host-adapted bacterial pathogens among the leading infectious causes of human morbidity and mortality. These microbes and related members of the genus Streptococcus produce an array of toxins that act against human cells or tissues, resulting in impaired immune responses and subversion of host physiological processes to benefit the invading microorganism. This toxin repertoire includes haemolysins, proteases, superantigens and other agents that ultimately enhance colonization and survival within the host and promote dissemination of the pathogen."
] |
The c-fms gene product of feline sarcoma virus and a murine retroviral vector containing a neomycin resistance gene
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The nucleotide sequence of a 5' segment of the human genomic c-fms proto-oncogene suggested that recombination between feline leukemia virus and feline c-fms sequences might have occurred in a region encoding the 5' untranslated portion of c-fms mRNA. The polyprotein precursor gP180gag-fms encoded by the McDonough strain of feline sarcoma virus was therefore predicted to contain 34 v-fms-coded amino acids derived from sequences of the c-fms gene that are not ordinarily translated from the proto-oncogene mRNA. The (gP180gag-fms) polyprotein was cotranslationally cleaved near the gag-fms junction to remove its gag gene-coded portion. Determination of the amino-terminal sequence of the resulting v-fms-coded glycoprotein, gp120v-fms, showed that the site of proteolysis corresponded to a predicted signal peptidase cleavage site within the c-fms gene product. Together, these analyses suggested that the linked gag sequences may not be necessary for expression of a biologically active v-fms gene product. The gag-fms sequences of feline sarcoma virus strain McDonough and the v-fms sequences alone were inserted into a murine retroviral vector containing a neomycin resistance gene. Both constructs were biologically active when transfected into NIH 3T3 cells and produced morphologically transformed foci at equivalent efficiencies. When transfected into a cell line (psi 2) expressing complementary viral gene functions, G418-resistant (Neor) cells containing either of these vector DNAs produced high titers of transforming viruses. Analysis of proteins produced in cells containing the vector lacking gag gene sequences showed that gP180gag-fms was not synthesized, whereas normal levels of both immature gp120v-fms and mature gp140v-fms were detected. The glycoprotein was efficiently transported to the cell surface, and it retained wild-type tyrosine kinase activity. We conclude that a cryptic hydrophobic signal peptide sequence in v-fms was unmasked by gag deletion, thereby allowing the correct orientation and transport of the v-fms gene product within membranous organelles. It seems likely that the proteolytic cleavage of gP180gag-fms is mediated by signal peptidase and that the amino termini of gp140v-fms and the c-fms gene product are identical.
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[
"Molecular clones of the retroviral oncogene v-fms were used to isolate recombinant bacteriophages containing c-fms proto-oncogene sequences from a human placental DNA library. Viral and cellular fms sequences were used in Southern blotting experiments with a panel of 32 human X mouse somatic cell hybrids to assign the human c-fms proto-oncogene to human chromosome 5.",
"In this study, we demonstrated the expression of a 170,000-Mr polyprotein in each of several McDonough feline sarcoma virus (FeSV)-transformed mink cell clones and one McDonough FeSV-transformed rat clone. This polyprotein designated McDonough FeSV P170, contained feline leukemia virus (FeLV) p15, p12, and p30 immunological determinants and shared two of its five [35S]methionine-labeled tryptic peptides with FeLV Pr180gag-pol. Both of these peptides were shown to be specific to the p30 component of Pr180gag-pol. The remaining McDonough FeSV P170 methionine-containing peptides were not represented within either FeLV Pr180gag-pol or Pr82env. Of interest, of the three peptides specific to the nonstructural component of McDonough FeSV P170, one was also represented in the 115,000-Mr polyproteins encoded by the Gardner and Snyder-Theilen strains of FeSV. These findings raise the possibility that the nonstructural components of polyproteins encoded by each of the three independently derived feline transforming viruses contained both common and unique regions. Moreover, if the sequences encoding these components are involved in transformation, as appears to be the case, our findings establish that the position of their insertion within the gag-pol region of the FeLV genome can vary among individual isolates.",
"Cells transformed by the McDonough strain of feline sarcoma virus (SM-FeSV) express a v-fms-encoded glycoprotein whose expression at the cell surface correlates with the transformed phenotype. The mouse mononuclear phagocyte growth factor CSF-1 specifically binds to SM-FeSV-transformed cells at high-affinity sites indistinguishable from those detected on normal feline macrophages. A monoclonal antibody to a v-fms-encoded epitope competed for CSF-1 binding to SM-FeSV-transformed cells, and chemical crosslinking demonstrated that murine CSF-1 bound to the v-fms gene product at the cell surface. Although SM-FeSV-transformed fibroblast lines were found to secrete CSF-1, the growth of transformed cells was not affected by antibodies to the v-fms gene product or to the growth factor. Tyrosine phosphorylation of the v-fms products in membranes was observed in the absence of CSF-1 and was not enhanced by addition of the murine growth factor. The data support the hypothesis that the c-fms protooncogene product is related, and possibly identical, to the CSF-1 receptor and suggest that the v-fms-encoded kinase functions in the absence of an exogenous growth factor.",
"The genomes of three independent isolates of feline sarcoma virus (FeSV) were compared by molecular hybridization techniques. Using complementary DNAs prepared from two strains, SM- and ST-FeSV, common complementary DNA'S were selected by sequential hybridization to FeSV and feline leukemia virus RNAs. These DNAs were shown to be highly related among the three independent sarcoma virus isolates. FeSV-specific complementary DNAs were prepared by selection for hybridization by the homologous FeSV RNA and against hybridization by fline leukemia virus RNA. Sarcoma virus-specific sequences of SM-FeSV were shown to differ from those of either ST- or GA-FeSV strains, whereas ST-FeSV-specific DNA shared extensive sequence homology with GA-FeSV. By molecular hybridization, each set of FeSV-specific sequences was demonstrated to be present in normal cat cellular DNA in approximately one copy per haploid genome and was conserved throughout Felidae. In contrast, FeSV-common sequences were present in multiple DNA copies and were found only in Mediterranean cats. The present results are consistent with the concept that each FeSV strain has arisen by a mechanism involving recombination between feline leukemia virus and cat cellular DNA sequences, the latter represented within the cat genome in a manner analogous to that of a cellular gene."
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Treatment of vulvovaginal candidiasis with tioconazole ointment or clotrimazole vaginal tablets.
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A total of 80 patients were equally randomized to receive a single dose of 6.5% tioconazole ointment or a 3-day course of 100-mg clotrimazole vaginal tablets for the treatment of vulvovaginal candidiasis. Of the 32 evaluable patients treated with tioconazole, 27 (84%) remained asymptomatic 4 weeks posttreatment, compared with 28 of 33 patients (85%) treated with clotrimazole. A total of 34 patients in each group could be evaluated for mycological response based on culture results 1 and 4 weeks after treatment. Twenty patients (59%) who received tioconazole and twenty-one patients (62%) who received clotrimazole remained culture negative 4 weeks after therapy. Of 40 patients who received tioconazole, 12 (30%) experienced local irritation or itching, compared with 2 of 40 patients (5%) treated with clotrimazole (P less than 0.01). Single-dose tioconazole ointment was as effective as a 3-day course of clotrimazole tablets, but significantly more patients in the tioconazole-treated group experienced local side effects.
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[
"Two hundred and two patients with symptoms, signs and mycological evidence of Candida vaginitis were entered in a single-blind trial comparing 6-day clotrimazole therapy with a control group receiving 6 days' nystatin therapy. Adequate data was collected on 69 clotrimazole and 72 nystatin treated patients for analysis. Judged by both the severity of symptoms and signs and the number of patients with negative mycological findings, 6-day clotrimazole therapy produced statistically significantly better results than obtained in the control group. When reviewed 4 weeks after starting therapy, 93% of the clotrimazole treated patinets had culturally negative results for Candida compared with 74% of the patients treated with nystatin. It is concluded that 6-day clotrimazole therapy is effective in the treatment of Candida vaginitis.",
"The accepted modern practice is to treat each sexually transmitted disease with the shortest possible course of treatment consistent with success. In candidal vulvovaginitis, six days is the minimum period that has so far been found to be successful, but we report here a further reduction to three days. Patients were given two clotrimazole pessaries nightly for three consecutive nights; the overall success rate was 89-4% one month after treatment. This compares favourably with the 93% cure rate reported with the six-day course of clotrimazole. With both the long and short courses, patients having their first attack of genital candidosis responded better than those with a history of previous infection. Short courses of clotrimazole treatment are particularly valuable in dealing with uncooperative women who stop treatment at the earliest possible moment. Clinical and laboratory diagnostic pitfalls and their possible influence upon the therapeutic outcome are also discussed."
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Non-invasive Cerebellar Stimulation in Stroke
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Non-invasive brain stimulation (NIBS) combined with behavioral training is a promising strategy to augment recovery after stroke. Current research efforts have been mainly focusing on primary motor cortex (M1) stimulation. However, the translation from proof-of-principle to clinical applications is not yet satisfactory. Possible reasons are the heterogeneous properties of stroke, generalization of the stimulation protocols, and hence the lack of patient stratification. One strategy to overcome these limitations could be the evaluation of alternative stimulation targets, like the cerebellum. In this regard, first studies provided evidence that non-invasive cerebellar stimulation can modulate cerebellar processing and linked behavior in healthy subjects. The cerebellum provides unique plasticity mechanisms and has vast connections to interact with neocortical areas. Moreover, the cerebellum could serve as a non-lesioned entry to the motor or cognitive system in supratentorial stroke. In the current article, we review mechanisms of plasticity in the cortico-cerebellar system after stroke, methods for non-invasive cerebellar stimulation, and possible target symptoms in stroke, like fine motor deficits, gait disturbance, or cognitive impairments, and discuss strategies for multi-focal stimulation.
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[
"We examined the patterns and variability of recovery post-stroke in multiple behavioral domains. A large cohort of first time stroke patients with heterogeneous lesions was studied prospectively and longitudinally at 1-2 weeks, 3 months and one year post-injury with structural MRI to measure lesion anatomy and in-depth neuropsychological assessment. Impairment was described at all timepoints by a few clusters of correlated deficits. The time course and magnitude of recovery was similar across domains, with change scores largely proportional to the initial deficit and most recovery occurring within the first three months. Damage to specific white matter tracts produced poorer recovery over several domains: attention and superior longitudinal fasciculus II/III, language and posterior arcuate fasciculus, motor and corticospinal tract. Finally, after accounting for the severity of the initial deficit, language and visual memory recovery/outcome was worse with lower education, while the occurrence of multiple deficits negatively impacted attention recovery.",
"Transcranial direct current stimulation (tDCS) is increasingly used to study motor- and non-motor-related functions of the cerebellum. The aim of the present study was to quantitatively review available studies to estimate the efficacy of cerebellar tDCS in altering motor- and cognitive-related behavioral performance in healthy volunteers. The present meta-analysis included 32 sham-controlled studies. Results from random effects modeling of the cumulative effect size demonstrated that anodal and cathodal tDCS to the cerebellum were effective in changing performance. No evidence for polarity-dependent effects of cerebellar tDCS was found. Current findings establish the feasibility to target motor and non-motor-related cerebellar functions with tDCS, but arguably due to anatomical differences between the cerebellum and cerebral cortex, the polarity of tDCS is not predictive of the direction of the behavioral changes in healthy volunteers.",
"Although cerebellar-cortical interactions have been studied extensively in animal models and humans using modern neuroimaging techniques, the effects of cerebellar stroke and focal lesions on cerebral cortical processing remain unknown. In the present study, we analyzed the large-scale functional connectivity at the cortical level by combining high-density electroencephalography (EEG) and source imaging techniques to evaluate and quantify the compensatory reorganization of brain networks after cerebellar damage. The experimental protocol comprised a repetitive finger extension task by 10 patients with unilateral focal cerebellar lesions and 10 matched healthy controls. A graph theoretical approach was used to investigate the functional reorganization of cortical networks. Our patients, compared with controls, exhibited significant differences at global and local topological level of their brain networks. An abnormal rise in small-world network efficiency was observed in the gamma band (30-40 Hz) during execution of the task, paralleled by increased long-range connectivity between cortical hemispheres. Our findings show that a pervasive reorganization of the brain network is associated with cerebellar focal damage and support the idea that the cerebellum boosts or refines cortical functions. Clinically, these results suggest that cortical changes after cerebellar damage are achieved through an increase in the interactions between remote cortical areas and that rehabilitation should aim to reshape functional activation patterns. Future studies should determine whether these hypotheses are limited to motor tasks or if they also apply to cerebro-cerebellar dysfunction in general.",
"The cerebellum is involved in sensorimotor operations, cognitive tasks and affective processes. Here, we revisit the concept of the cerebellar syndrome in the light of recent advances in our understanding of cerebellar operations. The key symptoms and signs of cerebellar dysfunction, often grouped under the generic term of ataxia, are discussed. Vertigo, dizziness, and imbalance are associated with lesions of the vestibulo-cerebellar, vestibulo-spinal, or cerebellar ocular motor systems. The cerebellum plays a major role in the online to long-term control of eye movements (control of calibration, reduction of eye instability, maintenance of ocular alignment). Ocular instability, nystagmus, saccadic intrusions, impaired smooth pursuit, impaired vestibulo-ocular reflex (VOR), and ocular misalignment are at the core of oculomotor cerebellar deficits. As a motor speech disorder, ataxic dysarthria is highly suggestive of cerebellar pathology. Regarding motor control of limbs, hypotonia, a- or dysdiadochokinesia, dysmetria, grasping deficits and various tremor phenomenologies are observed in cerebellar disorders to varying degrees. There is clear evidence that the cerebellum participates in force perception and proprioceptive sense during active movements. Gait is staggering with a wide base, and tandem gait is very often impaired in cerebellar disorders. In terms of cognitive and affective operations, impairments are found in executive functions, visual-spatial processing, linguistic function, and affective regulation (Schmahmann's syndrome). Nonmotor linguistic deficits including disruption of articulatory and graphomotor planning, language dynamics, verbal fluency, phonological, and semantic word retrieval, expressive and receptive syntax, and various aspects of reading and writing may be impaired after cerebellar damage. The cerebellum is organized into (a) a primary sensorimotor region in the anterior lobe and adjacent part of lobule VI, (b) a second sensorimotor region in lobule VIII, and (c) cognitive and limbic regions located in the posterior lobe (lobule VI, lobule VIIA which includes crus I and crus II, and lobule VIIB). The limbic cerebellum is mainly represented in the posterior vermis. The cortico-ponto-cerebellar and cerebello-thalamo-cortical loops establish close functional connections between the cerebellum and the supratentorial motor, paralimbic and association cortices, and cerebellar symptoms are associated with a disruption of these loops.",
"In this paper we demonstrate in the intact human the possibility of a non-invasive modulation of motor cortex excitability by the application of weak direct current through the scalp. Excitability changes of up to 40 %, revealed by transcranial magnetic stimulation, were accomplished and lasted for several minutes after the end of current stimulation. Excitation could be achieved selectively by anodal stimulation, and inhibition by cathodal stimulation. By varying the current intensity and duration, the strength and duration of the after-effects could be controlled. The effects were probably induced by modification of membrane polarisation. Functional alterations related to post-tetanic potentiation, short-term potentiation and processes similar to postexcitatory central inhibition are the likely candidates for the excitability changes after the end of stimulation. Transcranial electrical stimulation using weak current may thus be a promising tool to modulate cerebral excitability in a non-invasive, painless, reversible, selective and focal way.",
"In a previous study (Ivry and Keele, in press), cerebellar patients were found to be impaired on both a motor and a perceptual task which required accurate timing. This report presents case study analyses of seven patients with focal lesions in the cerebellum. The lesions were predominantly in the lateral, hemispheric regions for four of the patients. For the remaining three patients, the lesions were centered near the medial zone of the cerebellum. The clinical evaluation of the patients also was in agreement with the different lesion foci: lateral lesions primarily impaired fine motor coordination, especially apparent in movements with the distal extremities and medial lesions primarily disturbed balance and gait. All of the patients were found to have increased variability in performing rhythmic tapping when tapping with an effector (finger or foot) ipsilateral to the lesion in comparison to their performance with a contralateral effector. Separable estimates of a central timekeeper component and an implementation component were derived from the total variability scores following a model developed by Wing and Kristofferson (1973). This analysis indicated that the poor performance of patients with lateral lesions can be attributed to a deficit in the central timing process. In contrast, patients with medial lesions are able to accurately determine when to make a response, but are unable to implement the response at the desired time. A similar dissociation between the lateral and medial regions has been observed on a time perception task in patients with cerebellar atrophy. It is concluded that the lateral regions of the cerebellum are critical for the accurate functioning of an internal timing system.",
"Interference with brain rhythms by noninvasive transcranial stimulation that uses weak transcranial alternating current may reveal itself to be a new tool for investigating cortical mechanisms currently unresolved. Here, we aim to extend transcranial direct current stimulation (tDCS) techniques to transcranial alternating current stimulation (tACS). Parameters such as electrode size and position were taken from those used in previous tDCS studies. Motor evoked potentials (MEPs) revealed by transcranial magnetic stimulation (TMS), electroencephalogram (EEG)-power, and reaction times measured in a motor implicit learning task, were analyzed to detect changes in cortical excitability after 2-10 minutes of AC stimulation and sinusoidal DC stimulation (tSDCS) by using 1, 10, 15, 30, and 45 Hz and sham stimulation over the primary motor cortex in 50 healthy subjects (eight-16 subjects in each study). A significantly improved implicit motor learning was observed after 10 Hz AC stimulation only. No significant changes were observed in any of the analyzed frequency bands of EEG and with regard to the MEP amplitudes after AC or tSDCS stimulation. Similarly, if the anodal or cathodal DC stimulation was superimposed on 5, 10, and 15 Hz AC stimulation, the MEP amplitudes did not change significantly. Transcranial application of weak AC current may appear to be a tool for basic and clinical research in diseases with altered EEG activity. However, its effect seems to be weaker than tDCS stimulation, at least in the present context of stimulus intensity and duration. Further studies are required to extend cautiously the safety range and uncover its influence on neuronal circuitries.",
"Cerebellar transcranial direct current stimulation (cerebellar tDCS) is a non-invasive technique for inducing prolonged functional changes in the human cerebellum. Available data show that this simple and safe technique can modulate several motor and non-motor cerebellar functions in healthy humans. Also, preliminary data suggest that cerebellar tDCS is a possible therapeutic option in patients with cerebellar disorders. To provide a reference for those approaching this technique for the first time in healthy humans and patients, we here briefly and practically review the methodology for cerebellar tDCS, discussing electrode types, positions, DC duration and intensity. Recent modelling studies confirm that the electric field generated with the methodology reviewed here reaches the cerebellum at a strength within the range of values for modulating activity in the cerebellar neurons experimentally assessed.",
"Polarization is the passage of small constant direct currents through the brain. During the last 12 years some authors have investigated its therapeutic effectiveness in psychiatric patients with different and sometimes contradictory results. Although there seems to be a \"fairly consistent body of evidence concerned with the effects of direct currents applied to the head in psychiatric patients\" (Nias, 1976), only the procedure involving pulsating low-level currents (electrosleep) has received increasingly more attention in recent years, while polarization (constant d-c currents) is not even mentioned in most standard textbooks. This review concentrates on work dealing with behavioral and therapeutic effects of polarization. The procedure involves the continuous flow of low-level current (up to 1 ma) between cephalic and noncephalic electrodes during prolonged periods of time (usually hours), without inducing convulsions (as in electroconvulsive therapy) or sleep, the subject being almost unaware of the treatment. Because of its implications for research, attention is also devoted to some representative work on physiological effects of polarizing currents.",
"One hundred and sixty-two patients were referred to a rehabilitation unit after an acute stroke. The patterns of recovery of overall functional ability, arm function, walking and speech in 92 of 101 survivors have been analysed. In all modalities the majority of recovery occurs within 3 months; although improvement is seen thereafter it does not reach statistical significance. Possible reasons for the apparent lack of late recovery are discussed."
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Syn, a new member of the tyrosine kinase oncogene family
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An src/yes-related novel gene named syn (SYN in human gene nomenclature) has been identified in the human genome on chromosome 6 and characterized by molecular cloning. Nucleotide sequence analysis of cDNA clones showed that the c-syn gene could encode a protein-tyrosine kinase that is very similar in primary structure to the v-yes and human c-src proteins. A 2.8-kilobase transcript of the c-syn gene, which differs in size from those of the c-yes, c-src, and c-fgr genes, was observed in various cell types. These results show that syn is a new member of the tyrosine kinase oncogene family.
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[
"Two human genes homologous to the raf/mil oncogene have been cloned and sequenced. One, c-raf-2, is a processed pseudogene; the other, c-raf-1, contains nine exons homologous to both raf and mil and two additional exons homologous to mil. A 3' portion of c-raf-1 containing six of the seven amino acid differences relative to murine v-raf can substitute for the 3' portion of v-raf in a transformation assay. Sequence homologies between c-raf-1 and Moloney leukemia virus at both ends of v-raf indicate that the viral gene was acquired by homologous recombination. Although the data are consistent with the traditional model of retroviral transduction, they also raise the possibility that the transduction occurred in a double crossover event between proviral DNA and the murine gene.",
"A new method for determining nucleotide sequences in DNA is described. It is similar to the \"plus and minus\" method [Sanger, F. & Coulson, A. R. (1975) J. Mol. Biol. 94, 441-448] but makes use of the 2',3'-dideoxy and arabinonucleoside analogues of the normal deoxynucleoside triphosphates, which act as specific chain-terminating inhibitors of DNA polymerase. The technique has been applied to the DNA of bacteriophage varphiX174 and is more rapid and more accurate than either the plus or the minus method.",
"The dideoxy chain termination method using deoxy-7-deazaguanosine triphosphate (dc7GTP) in place of dGTP was found to be very useful. Sequencing of a part of the human N-myc gene having 85% GC content is impossible by the original method using dGTP, because of compression of bands. However, the nucleotide sequence of this part was unambiguously determined by analysis of both strands by the modified method. Use of dc7GTP is concluded to improve the dideoxy chain termination method for DNA sequencing.",
"We determined the nucleotide sequences of all coding regions and a significant part of the flanking regions of the chicken c-src gene, which is a cellular homolog of the v-src gene of Rous sarcoma virus. The c-src gene consists of 12 exons; the boundaries of the exons were determined by assuming that the amino acid sequence of its product, pp60c-src, is basically the same as that of pp60v-src. The deduced amino acid sequence of pp60c-src was very similar to that of pp60v-src, but the last 19 carboxy-terminal amino acids of pp60c-src were replaced by a new set of 12 amino acids of pp60v-src. The sequence encoding the carboxy-terminal sequence of pp60v-src was found 900 bp downstream from the termination codon of the c-src gene. We suggest that the c-src sequence was captured by a virus through recombination at both sides of the c-src gene, and that the recombinations occurred at the level of proviral DNA.",
"The nucleotide sequence of the 3' two-thirds of a highly conserved, molecularly cloned human cellular src gene (c-src) has been determined. This region of the c-src gene encodes the tyrosine kinase domain of the cellular src protein (pp60c-src) and corresponds to exons 6 through 12 of the chicken c-src gene, as well as nucleotides 545 to 1542 of the Rous sarcoma virus src gene (v-src). The human c-src sequence is very strongly conserved with respect to both the chicken c-src and the Rous sarcoma virus v-src genes, with nearly 90% nucleotide homology observed in this region. Amino acid sequence conservation in this region is even greater; 98% of the amino acids are conserved between human and chicken c-src. Furthermore, the exon sizes and the locations of the exon-intron boundaries are identical in the human and chicken c-src genes. However, sequences within the introns have not been conserved, and the introns within the human c-src gene are significantly larger than the corresponding introns within the chicken c-src gene. The strong amino acid conservation between the carboxy-terminal two-thirds of pp60c-src of species as divergent as humans and chickens suggests that this portion of the pp60c-src protein specifies one or more functional domains that are of great importance to some aspect of normal cellular growth or differentiation."
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Mechanical stiffness of a 3D hydrogel alters the behavior and myofibroblast-like properties of human mammary fibroblasts
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Carcinoma associated fibroblasts (CAFs or myofibroblasts) are activated fibroblasts which participate in breast tumor growth, angiogenesis, invasion, metastasis and therapy resistance. As such, recent efforts have been directed toward understanding the factors responsible for activation of the phenotype. In this study, we have investigated how changes in the mechanical stiffness of a 3D hydrogel alter the behavior and myofibroblast-like properties of human mammary fibroblasts (HMFs).
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[
"Mast cells (MC) are a bone marrow-derived, long-lived, heterogeneous cellular population that function both as positive and negative regulators of immune responses. They are arguably the most productive chemical factory in the body and influence other cells through both soluble mediators and cell-to-cell interaction. MC are commonly seen in various tumors and have been attributed alternatively with tumor rejection or tumor promotion. Tumor-infiltrating MC are derived both from sentinel and recruited progenitor cells. MC can directly influence tumor cell proliferation and invasion but also help tumors indirectly by organizing its microenvironment and modulating immune responses to tumor cells. Best known for orchestrating inflammation and angiogenesis, the role of MC in shaping adaptive immune responses has become a focus of recent investigations. MC mobilize T cells and antigen-presenting dendritic cells. They function as intermediaries in regulatory T cells (Treg)-induced tolerance but can also modify or reverse Treg-suppressive properties. The central role of MC in the control of innate and adaptive immunity endows them with the ability to tune the nature of host responses to cancer and ultimately influence the outcome of disease and fate of the cancer patient.",
"Human and bovine capillary endothelial cells were switched from growth to apoptosis by using micropatterned substrates that contained extracellular matrix-coated adhesive islands of decreasing size to progressively restrict cell extension. Cell spreading also was varied while maintaining the total cell-matrix contact area constant by changing the spacing between multiple focal adhesion-sized islands. Cell shape was found to govern whether individual cells grow or die, regardless of the type of matrix protein or antibody to integrin used to mediate adhesion. Local geometric control of cell growth and viability may therefore represent a fundamental mechanism for developmental regulation within the tissue microenvironment.",
"Platelets are thought to participate in tumor metastasis. However, the relationship between platelet count and prognosis in pancreatic cancer remains unresolved. A chart review of patients undergoing resection for pancreatic adenocarcinoma was undertaken. Demographic, perioperative, and outcome data were collected. Kaplan-Meier survival and Cox regression analyses were used to determine the impact of preoperative platelet count on survival. Between June 1995 and March 2003, 109 patients (63% male) with a median age of 68 years (range 42 to 85 years) underwent resection for pancreatic cancer. Univariate analysis demonstrated that platelet count, lymph node or margin status, and histology were associated with survival. In multivariate analysis, the association between increased platelet count and poor survival maintained significance. Increased preoperative platelet count is associated with adverse survival outcome in patients undergoing resection for pancreatic cancer. Antiplatelet medications warrant further study in an attempt to improve survival in these patients.",
"Generating an anti-tumor immune response is a multi-step process that is executed by effector T cells that can recognize and kill tumor targets. However, tumors employ multiple strategies to attenuate the effectiveness of T-cell-mediated attack. They achieve this by interfering with nearly every step required for effective immunity, from deregulation of antigen-presenting cells to establishment of a physical barrier at the vasculature that prevents homing of effector tumor-rejecting cells and the suppression of effector lymphocytes through the recruitment and activation of immunosuppressive cells such as myeloid-derived suppressor cells, tolerogenic monocytes, and T regulatory cells. Here, we review the ways in which tumors exert immune suppression and highlight the new therapies that seek to reverse this phenomenon and promote anti-tumor immunity. Understanding anti-tumor immunity, and how it becomes disabled by tumors, will ultimately lead to improved immune therapies and prolonged survival of patients.",
"Myofibroblasts derived from portal fibroblasts are important fibrogenic cells in the early stages of biliary fibrosis. In contrast to hepatic stellate cells, portal fibroblasts have not been well studied in vitro, and little is known about their myofibroblastic differentiation. In this article we report the isolation and characterization of rat portal fibroblasts in culture. We demonstrate that primary portal fibroblasts undergo differentiation to alpha-smooth muscle actin-expressing myofibroblasts over 10-14 days. Marker analysis comparing portal fibroblasts to hepatic stellate cells demonstrated that these are distinct populations and that staining with elastin and desmin can differentiate between them. Portal fibroblasts expressed elastin at all stages in culture but never expressed desmin, whereas hepatic stellate cells consistently expressed desmin but never elastin. Immunostaining of rat liver tissue confirmed these results in vivo. Characterization of portal fibroblast differentiation in culture demonstrated that these cells required transforming growth factor-beta (TGF-beta): cells remained quiescent in the presence of a TGF-beta receptor kinase inhibitor, whereas exogenous TGF-beta1 enhanced portal fibroblast alpha-smooth muscle actin expression and stress fiber formation. In contrast, platelet-derived growth factor inhibited myofibroblastic differentiation. Portal fibroblasts were also dependent on mechanical tension for myofibroblastic differentiation, and cells cultured on polyacrylamide supports of variable stiffness demonstrated an increasingly myofibroblastic phenotype as stiffness increased. Portal fibroblasts are morphologically and functionally distinct from hepatic stellate cells. Portal fibroblast myofibroblastic differentiation can be modeled in culture and requires both TGF-beta and mechanical tension.",
"Cancers develop in complex tissue environments, which they depend on for sustained growth, invasion and metastasis. Unlike tumor cells, stromal cell types within the tumor microenvironment (TME) are genetically stable and thus represent an attractive therapeutic target with reduced risk of resistance and tumor recurrence. However, specifically disrupting the pro-tumorigenic TME is a challenging undertaking, as the TME has diverse capacities to induce both beneficial and adverse consequences for tumorigenesis. Furthermore, many studies have shown that the microenvironment is capable of normalizing tumor cells, suggesting that re-education of stromal cells, rather than targeted ablation per se, may be an effective strategy for treating cancer. Here we discuss the paradoxical roles of the TME during specific stages of cancer progression and metastasis, as well as recent therapeutic attempts to re-educate stromal cells within the TME to have anti-tumorigenic effects.",
"Blood vessels deliver oxygen and nutrients to every part of the body, but also nourish diseases such as cancer. Over the past decade, our understanding of the molecular mechanisms of angiogenesis (blood vessel growth) has increased at an explosive rate and has led to the approval of anti-angiogenic drugs for cancer and eye diseases. So far, hundreds of thousands of patients have benefited from blockers of the angiogenic protein vascular endothelial growth factor, but limited efficacy and resistance remain outstanding problems. Recent preclinical and clinical studies have shown new molecular targets and principles, which may provide avenues for improving the therapeutic benefit from anti-angiogenic strategies.",
"The extensional signals in cross-talk between stromal cells and tumor cells generated from extracellular matrix molecules, soluble factor, and cell-cell adhesion complexes cooperate at the extra- and intracellular level in the tumor microenvironment. CAFs are the primary type of stromal cells in the tumor microenvironment and play a pivotal role in tumorigenesis and development. Hitherto, there is hardly any systematic analysis of the intrinsic relationship between CAFs function and its abnormal signaling pathway. The extreme complexity of CAFs' features and their role in tumor development are needed to be further investigated. We primary cultured CAFs and NFs from early stages of breast cancer tissue and identified them using their biomarker by immunohistochemistry for Fibronectin, α-SMA and FAP. Microarray was applied to analyze gene expression profiles of human breast CAFs and the paired NFs. The Up-regulated genes classified by Gene Ontology, signal pathways enriched by DAVID pathway analysis. Abnormal signaling pathways in breast cancer CAFs are involved in cell cycle, cell adhesion, signal transduction and protein transport being reported in CAFs derived from other tumors. Significantly, the altered ATM signaling pathway, a set of cell cycle regulated signaling, and immune associated signaling are identified to be changed in CAFs. CAFs have the vigorous ability of proliferation and potential of invasion and migration comparing with NFs. CAFs could promote breast cancer cell invasion under co-culture conditions through up-regulated CCL18 and CXCL12. Consistently with its biologic behavior, the gene expression profiling analyzed by microarray shows that some of key signaling pathways, such as cell cycle, cell adhesion, and secreting factors play an important role in CAFs. The altered ATM signaling pathway is abnormally active in the early stage of breast cancer. The set of immune associated signaling may be involved in tumor cell immune evasion.",
"Leukocytes and their soluble mediators play important regulatory roles in all aspects of solid tumor development. While immunotherapeutic strategies have conceptually held clinical promise, with the exception of a small percentage of patients, they have failed to demonstrate effective, consistent, and durable anti-cancer responses. Several subtypes of leukocytes that commonly infiltrate solid tumors harbor immunosuppressive activity and undoubtedly restrict the effectiveness of these strategies. Several of these same immune cells also foster tumor development by expression of potent protumor mediators. Given recent evidence revealing that immune-based mechanisms regulate the response to conventional cytotoxic therapy, it seems reasonable to speculate that tumor progression could be effectively diminished by combining cytotoxic strategies with therapies that blunt protumor immune-based effectors and/or neutralize those that instead impede development of desired anti-tumor immunity, thus providing synergistic effects between traditional cytotoxic and immune-modulatory approaches.",
"The emergence of the adaptive immune system took a toll in the form of pathologies mediated by self-reactive cells. Regulatory T cells (T reg cells) exert a critical brake on responses of T and B lymphocytes to self- and foreign antigens. Here, we asked whether T reg cells are required to restrain NK cells, the third lymphocyte lineage, whose features combine innate and adaptive immune cell properties. Although depletion of T reg cells led to systemic fatal autoimmunity, NK cell tolerance and reactivity to strong activating self- and non-self-ligands remained largely intact. In contrast, missing-self responses were increased in the absence of T reg cells as the result of heightened IL-2 availability. We found that IL-2 rapidly boosted the capacity of NK cells to productively engage target cells and enabled NK cell responses to weak stimulation. Our results suggest that IL-2-dependent adaptive-innate lymphocyte cross talk tunes NK cell reactivity and that T reg cells restrain NK cell cytotoxicity by limiting the availability of IL-2."
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Anaerobically induced gene fusions in Escherichia coli.
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A collection of anaerobically induced gene fusions were isolated, and representative isolates were characterized with respect to their regulatory properties, phenotypes, and approximate map locations. Four fusion strains that had defects in the anaerobic metabolism of asparagine or aspartate were found. These fusions were all repressed by alternate electron acceptors, ammonia, and glucose but were induced by other sugars. Several other fusion strains which demonstrated no observable phenotype showed diverse regulatory responses. The anaerobically induced fusions were scattered around the Escherichia coli chromosome more or less at random, suggesting that all the isolates examined were in separate genes.
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[
"l-Asparaginase II was synthesized at constant rates by Escherichia coli under anaerobic conditions. The enzyme was produced optimally by bacteria grown between pH 7 and 8 at 37 C. Although some enzyme was formed aerobically, between 100 and 1,000 times more asparaginase II was produced during anaerobic growth in media enriched with high concentrations of a variety of amino acids. Bacteria grown under these conditions should provide a rich starting material for the large-scale production of the enzyme. No single amino acid specifically induced the synthesis of the asparaginase, nor did l-asparagine, even when it was used as the only source of nitrogen. The enzyme was produced at lower rates in the presence of sugars; glucose was the most inhibitory.",
"Cytochrome c552, which has been implicated as an electron carrier for nitrite reduction by Escherichia coli, has been separated from NADH-nitrite oxidoreductase activity. The cytochrome is therefore not required for the reduction of nitrite by NADH in vitro. Nevertheless, some mutants which were selected by their inability to use nitrite as a nitrogen source during anaerobic growth synthesize neither NADH-nitrite oxidoreductase nor cytochrome c552. The defects in these mutants are due to mutations in a single gene, nirA, which is located at about minute 29 on the recalibrated linkage map. Experiments with an F' plasmid which carries a nirA+ allele established that nirA+ is dominant to the defective allele. Other mutants, defective in nitrate reductase activity because of mutations in the chlA or chlB genes, synthesized nitrite reductase and cytochrome c552 in the absence of nitrate or nitrite. A mutant with a defective fnr gene was also NirA- and, conversely, nirA mutants were Fnr-. In a series of transduction experiments, attempts to separate the nirA and fnr defects were unsuccessful. Furthermore, no complementation was observed when an F' plasmid carrying a defective nirA allele was transferred into the fnr strain. It is concluded that the fnr gene described by Lambden & Guest (1976) is identical to the nirA gene and that its product affects the synthesis or assembly of a variety of anaerobic redox enzymes which include nitrite reductase, cytochrome c552, nitrate reductase, fumarate reductase and formate hydrogenlyase.",
"It is shown here that a plasmid (p29) derived from the transducing phage lambda aspC2 (Christiansen and Pedersen 1981) codes for pyruvate formate-lyase. The identity of the 80 kilodaltons (kd) gene product of plasmid p29 with the pyruvate formate-lyase polypeptide was proven (i) by co-migration of the gene product expressed in the maxicell system with purified enzyme on O'Farrell gels, and (ii) by comparison of the peptide maps obtained from limited proteolysis. In vivo the 80 kd form of the enzyme was proteolytically converted to a 78 kd polypeptide. The two polypeptides (80 kd and 78 kd) and their charge isomers present in purified enzyme preparations are therefore products of a single gene. Aerobically grown cells of Escherichia coli contained a basal level of pyruvate formate-lyase which was derepressed 5- to 10-fold under anaerobiosis. Derepression also occurred during anaerobic growth on glycerol plus fumarate. Presence of plasmid p29 caused overproduction of pyruvate formatelyase, 11-fold upon anaerobic growth on glucose, 14-fold upon aerobic growth on glucose and 33-fold upon aerobic growth at the expense of D-lactate.",
"I used a chlC-lac operon fusion to study regulatory mutations which affect nitrate reductase expression in Escherichia coli. A NarL- mutant apparently lacks a nitrate-specific positive regulatory component. Furthermore, an fnr (nirR) mutation prevented enzyme induction under any conditions. These data are consistent with a two-step, positive control model for nitrate reductase regulation.",
"A new method is described for the isolation of different mutants defective in formic dehydrogenase activity measured with benzyl viologen as electron acceptor."
] |
Elongin-Cullin-SOCS box E3 ligase mediates a long-lasting change in serotonin-dependent feeding behavior induced by heat stress
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Neuromodulatory cells transduce environmental information into long-lasting behavioral responses. However, the mechanisms governing how neuronal cells influence behavioral plasticity are difficult to characterize. Here, we adapted the translating ribosome affinity purification (TRAP) approach in C. elegans to profile ribosome-associated mRNAs from three major tissues and the neuromodulatory dopaminergic and serotonergic cells. We identified elc-2, an Elongin C ortholog, specifically expressed in stress-sensing amphid neuron dual ciliated sensory ending (ADF) serotonergic sensory neurons, and we found that it plays a role in mediating a long-lasting change in serotonin-dependent feeding behavior induced by heat stress. We demonstrate that ELC-2 and the von Hippel-Lindau protein VHL-1, components of an Elongin-Cullin-SOCS box (ECS) E3 ubiquitin ligase, modulate this behavior after experiencing stress. Also, heat stress induces a transient redistribution of ELC-2, becoming more nuclearly enriched. Together, our results demonstrate dynamic regulation of an E3 ligase and a role for an ECS complex in neuromodulation and control of lasting behavioral states.
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[
"In the stomatogastric nervous system of the crab, Cancer borealis, a set of 4 serotonergic/cholinergic proprioceptive neurons, called gastropyloric receptor (GPR) cells, have effects on the pyloric motor pattern. In a semi-intact foregut preparation, the GPR cells are not activated by movements of the pyloric filter; instead they respond to the slower movements of the gastric mill (Katz et al., 1989). Thus, their activity is not synchronized to the pyloric motor pattern. However, when the GPR cells are stimulated in an in vitro preparation in a manner that resembles their normal firing pattern, they produce dramatic effects on the pyloric motor pattern. These effects include: (1) a prolonged increase in the pyloric cycle frequency, (2) a momentary pause in the motor pattern, (3) transient inhibition of some motor neurons, (4) strong excitation of other motor neurons, and (5) altered phase relationships of the different components of the motor pattern. These changes in the motor pattern are due to direct effects of the GPR cells on neurons in the pyloric central pattern generator (CPG). All of the cells in the pyloric circuit appear to receive GPR input. However, only 2 neurons receive detectable rapid nicotinic synaptic potentials. The other neurons receive only slower neuromodulatory input from GPR stimulation. The neuromodulatory effects include burst enhancement, plateau potential enhancement, excitation, and inhibition. These modulatory effects are largely mimicked by bath-applied serotonin (5-HT). Thus, primary sensory neurons can alter the production of motor patterns by a CPG through a phase-independent mechanism; these proprioceptors do not need to fire at a precise time in the cycle to be effective because their effects are mediated through the slower actions of the neuromodulator 5-HT.",
"Neurosecretory release sites lack distinct postsynaptic partners, yet target to specific circuits. This targeting specificity regulates local release of neurotransmitters and modulation of adjacent circuits. How neurosecretory release sites target to specific regions is not understood. Here we identify a molecular mechanism that governs the spatial specificity of extrasynaptic neurosecretory terminal (ENT) formation in the serotonergic neurosecretory-motor (NSM) neurons of Caenorhabditis elegans. We show that postembryonic arborization and neurosecretory terminal targeting of the C. elegans NSM neuron is dependent on the Netrin receptor UNC-40/DCC. We observe that UNC-40 localizes to specific neurosecretory terminals at the time of axon arbor formation. This localization is dependent on UNC-6/Netrin, which is expressed by nerve ring neurons that act as guideposts to instruct local arbor and release site formation. We find that both UNC-34/Enabled and MIG-10/Lamellipodin are required downstream of UNC-40 to link the sites of ENT formation to nascent axon arbor extensions. Our findings provide a molecular link between release site development and axon arborization and introduce a novel mechanism that governs the spatial specificity of serotonergic ENTs in vivo.",
"Stress response is a fundamental form of behavioral and physiological plasticity. Here we describe how serotonin (5HT) governs stress behavior by regulating DAF-2 insulin/IGF-1 receptor signaling to the DAF-16/FOXO transcription factor at the nexus of development, metabolism, immunity, and stress responses in C. elegans. Serotonin-deficient tph-1 mutants, like daf-2 mutants, exhibit DAF-16 nuclear accumulation and constitutive physiological stress states. Exogenous 5HT and fluoxetine (Prozac) prevented DAF-16 nuclear accumulation in wild-type animals under stresses. Genetic analyses imply that DAF-2 is a downstream target of 5HT signaling and that distinct serotonergic neurons act through distinct 5HT receptors to influence distinct DAF-16-mediated stress responses. We suggest that modulation of FOXO by 5HT represents an ancient feature of stress physiology and that the C. elegans is a genetically tractable model that can be used to delineate the molecular mechanisms and drug actions linking 5HT, neuroendocrine signaling, immunity, and mitochondrial function.",
"Although transcription factors are known to regulate synaptic plasticity, downstream genes that contribute to neural circuit remodeling are largely undefined. In Caenorhabditis elegans, GABAergic Dorsal D (DD) motor neuron synapses are relocated to new sites during larval development. This remodeling program is blocked in Ventral D (VD) GABAergic motor neurons by the COUP-TF (chicken ovalbumin upstream promoter transcription factor) homolog, UNC-55. We exploited this UNC-55 function to identify downstream synaptic remodeling genes that encode a diverse array of protein types including ion channels, cytoskeletal components, and transcription factors. We show that one of these targets, the Iroquois-like homeodomain protein, IRX-1, functions as a key regulator of remodeling in DD neurons. Our discovery of irx-1 as an unc-55-regulated target defines a transcriptional pathway that orchestrates an intricate synaptic remodeling program. Moreover, the well established roles of these conserved transcription factors in mammalian neural development suggest that a similar cascade may also control synaptic plasticity in more complex nervous systems.",
"The inactivation of the von Hippel-Lindau (VHL) gene predisposes affected individuals to VHL syndrome and is an early genetic event associated with sporadic renal cell carcinoma and CNS hemangioblastomas. The VHL protein (pVHL) has been shown to form a stable complex with elongin B and elongin C, two factors that stabilize and activate the transcription elongation factor elongin A. Here, Hs-CUL-2, a member of the recently identified multigene family, the cullins, is shown to specifically associate with the trimeric pVHL-elongin B-C (VBC) complex in vitro and in vivo. Nearly 70% of naturally occurring cancer-predisposing mutations of VHL disrupt this interaction. The pVHL-Hs-CUL-2 association is strictly dependent on the integrity of the trimeric VBC complex. Immunofluorescence studies show Hs-CUL-2 to be a cytosolic protein that can be translocated to the nucleus by pVHL. Recently it has been shown that a yeast Hs-CUL-2 homolog, Cdc53, is part of a ubiquitin protein ligase complex that targets cell cycle proteins for degradation by the ubiquitin proteolytic pathway. In Caenorhabditis elegans, a null mutation of another Hs-cul-2 homolog, Ce-cul-1, results in hyperplasia in all tissues and is required for cell cycle exit. Hence, Hs-cul-2 may be required for VHL function and, therefore, may be a candidate human tumor-suppressor gene.",
"The simple and well-described structure of the C. elegans nervous system offers an unprecedented opportunity to identify the genetic programs that define the connectivity and function of individual neurons and their circuits. A correspondingly precise gene expression map of C. elegans neurons would facilitate the application of genetic methods toward this goal. Here we describe a powerful new approach, SeqCeL (RNA-Seq of C. elegans cells) for producing gene expression profiles of specific larval C. elegans neurons. We have exploited available GFP reporter lines for FACS isolation of specific larval C. elegans neurons for RNA-Seq analysis. Our analysis showed that diverse classes of neurons are accessible to this approach. To demonstrate the applicability of this strategy to rare neuron types, we generated RNA-Seq profiles of the NSM serotonergic neurons that occur as a single bilateral pair of cells in the C. elegans pharynx. These data detected >1,000 NSM enriched transcripts, including the majority of previously known NSM-expressed genes. This work offers a simple and robust protocol for expression profiling studies of post-embryonic C. elegans neurons and thus provides an important new method for identifying candidate genes for key roles in neuron-specific development and function.",
"The VHL tumour-suppressor gene (TSG) has a critical 'gatekeeper' role in regulating growth and differentiation of human kidney cells, and inactivation of the VHL gene is the most frequent genetic event in human kidney cancer. There are many similarities between the genetics of the VHL and retinoblastoma TSGs, but the VHL tumourigenesis model is more complex. Here, we examine the current knowledge of the genetics and functional aspects of the VHL TSG, and emphasize how the VHL gene provides a paradigm that illustrates many aspects of TSG biology."
] |
The crystal structure of yeast tRNAAsp.
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The crystal structure of yeast tRNAAsp enables visualization of an anticodon-anticodon interaction at the molecular level. Except for differences in the base stacking and twist, the overall conformation of the anticodon loop is quite similar to that of yeast tRNAPhe. The anticodon nucleotide triplets, GUC, of two symmetrically related molecules form a minihelix of the RNA type 11. The modified base m1G37 stacks on both sides of the triplets and enforces the continuity with the anticodon stems. Anticodon association induces long-range conformational changes in the region of the dihydrouracil and thymine loops. Experimental evidence includes the variation in the distribution of temperature factors between yeast tRNAPhe and tRNAAsp, the difference in the self-splitting patterns of tRNAAsp in crystal and solution, and the differential accessibility of cytidines to dimethyl sulfate in free and duplex tRNAAsp. These observations are linked to the fragility and disruption of the G.C Watson-Crick base pair at the corner of the molecule formed by the dihydrouracil and thymine loops.
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[
"Three chemical reactions can probe the secondary and tertiary interactions of RNA molecules in solution. Dimethyl sulfate monitors the N-7 of guanosines and senses tertiary interactions there, diethyl pyrocarbonate detects stacking of adenosines, and an alternate dimethyl sulfate reaction examines the N-3 of cytidines and thus probes base pairing. The reactions work between 0 degrees C and 90 degrees C and at pH 4.5--8.5 in a variety of buffers. As an example we follow the progressive denaturation of yeast tRNAPhe terminally labeled with 32P as the tertiary and secondary structures sequentially melt out. A single autoradiograph of a terminally labeled molecule locates regions of higher-order structure and identifies the bases involved.",
"The structure of the complex formed in solution between yeast tRNAPhe and Escherichia coli tRNAGlu2 has been studied by small-angle x-ray scattering. The complex has a radius of gyration of 4.0 nm and an electron-pair distance distribution that is incompatible with a model composed to two tRNAs joined at their complementary anticodons and exhibiting the L shape seen in the crystal. Instead a model in which the two tRNAs, still bound via the anticodons, assume a conformation with the acceptor arms folded toward the anticodon arms agrees with the observed scattering curves.",
"We present and review experiments that identify points of close approach of the RNA polymerase to two promoters, lac UV5 and T7 A3. We identify the contacts to the phosphates along the DNA backbone, to the N7s of guanines in the major groove and the N3s of adenines in the minor groove, and to the methyl groups of thymines. These contacts to the two promoters are strikingly homologous in space, as shown on three-dimensional models, and identify major regions of interactions lying on one side of the DNA molecule (at -35 and -16), as well as further areas extending through the Pribnow box. Both promoters are unwound similarly by the polymerase, across a region of about twelve bases extending from the middle of the Pribnow box to just beyond the RNA start site. We discuss the areas of interaction in the context of promoter homologies and promoter mutations. The disposition of the contacts in space suggests a model for the pathway along which the RNA polymerase binds to promoters."
] |
The 55-kD protein is involved in the formation of microfilaments in both microspikes and stress fibers
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The 55-kD protein is a new actin-bundling protein purified from HeLa cells (Yamashiro-Matsumura, S., and F. Matsumura, 1985, J. Biol. Chem., 260:5087-5097). We have prepared monoclonal antibodies against the 55-kD protein and examined its intracellular localization, as well as its spatial relationships with other components of microfilaments in cultured cells by double-label immunofluorescence. The localization of the 55-kD protein is similar to that of actin. The antibody to the 55-kD protein stained strongly both microspikes and stress fibers. The 55-kD protein was found from the basal portions to the extremities of microspikes while alpha-actinin was localized only in the basal portions. In stress fibers, the 55-kD protein was found rather continuously in comparison to the periodic localizations of alpha-actinin and tropomyosin. Although fimbrin is located in microspikes and ruffling membranes, fimbrin is hardly found in stress fibers unlike the 55-kD protein. These observations coupled with the actin-bundling activity of the 55-kD protein imply that the 55-kD protein is involved in the formation of microfilament bundles in both microspikes and stress fibers.
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[
"Fodrin (formerly designated 26 and 27) comprises two polypeptides (250,000 and 240,000 mol wt) that are axonally transported at a maximum time-averaged velocity of 40 mm/d--slower than the most rapidly moving axonally transported proteins, but faster than at least three additional groups of proteins. In this communication, we report the intracellular distribution of fodrin. Fodrin was purified from guinea pig brain, and a specific antifodrin antibody was produced in rabbit and used to localize fodrin in tissue sections and cultured cells by means of indirect immunofluorescence. Fodrin antigens were highly concentrated in the cortical cytoplasm of neurons and also nonneuronal tissues (e.g., skeletal muscle, uterus, intestinal epithelium). Their disposition resembles a lining of the cell: hence, the designation fodrin (from Greek fodros, lining). In cultured fibroblasts, immunofluorescently labeled fodrin antigens were arranged in parallel arrays of bands in the plane of the plasma membrane, possibly reflecting an exclusion of labeled fodrin from some areas occupied by stress fibers. The distribution of fodrin antigens in mouse 3T3 cells transformed with simian virus 40 was more diffuse, indicating that the disposition of fodrin is responsive to altered physiological states of the cell. When mixtures of fodrin and F-actin were centrifuged, fodrin cosedimented with the actin, indicating that these proteins interact in vitro. We conclude that fodrin is a specific component of the cortical cytoplasm of many cells and consider the possibilities: (a) that fodrin may be indirectly attached to the plasma membrane via cortical actin filaments; (b) that fodrin may be mobile within the cortical cytoplasm and that, in axons, a cortical lining may be in constant motion relative to the internal cytoplasm; and (c) that fodrin could serve to link other proteins and organelles to a submembrane force-generating system.",
"This report presents the appearance of rapidly frozen, freeze-dried cytoskeletons that have been rotary replicated with platinum and viewed in the transmission electron microscope. The resolution of this method is sufficient to visualize individual filaments in the cytoskeleton and to discriminate among actin, microtubules, and intermediate filaments solely by their surface substructure. This identification has been confirmed by specific decoration with antibodies and selective extraction of individual filament types, and correlated with light microscope immunocytochemistry and gel electrophoresis patterns. The freeze-drying preserves a remarkable degree of three-dimensionality in the organization of these cytoskeletons. They look strikingly similar to the meshwork of strands or \"microtrabeculae\" seen in the cytoplasm of whole cells by high voltage electron microscopy, in that the filaments form a lattice of the same configutation and with the same proportions of open area as the microtrabeculae seen in whole cells. The major differences between these two views of the structural elements of the cytoplasmic matrix can be attributed to the effects of aldehyde fixation and dehydration. Freeze-dried cytoskeletons thus provide an opportunity to study--at high resolution and in the absence of problems caused by chemical fixation--the detailed organization of filaments in different regions of the cytoplasm and at different stages of cell development. In this report the pattern of actin and intermediate filament organization in various regions of fully spread mouse fibroblasts is described."
] |
Electrolyte transport by in vitro rabbit colon.
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Descending rabbit colon, stripped of muscularis externa, absorbs Na and Cl under short-circuit conditions and exhibits a residual ion flux, consistent with HCO3 secretion, whose magnitude is approximately equal to the rate of active Cl absorption. Net K transport was not observed under short-circuit conditions. The results of ion replacement studies and of treatment with ouabain or amiloride suggest that the short-circuit current ISC is determined solely by the rate of active Na transport and that the net movements of Cl and HCO3 are mediated by a Na-independent, electrically-neutral, anion exchange process. Cyclic AMP stimulates an electrogenic Cl secretion, abolishes HCO3 secretion but does not affect the rate of Na absorption under short-circuit conditions. Studies of the effect of transepithelial potential difference on the serosa-to-mucosa fluxes Jism of Na, K and Cl suggest that JNasm,JIsm and one-third of JCl-sm may be attributed to ionic diffusion. The permeabilities of the passive conductance pathway(s) are such that Pk:PNa:PCl= 1.0:0.07:0.11. Electrolyte transport by in vitro rabbit colon closely resembles that reported from in vivo studies of mammalian colon and thus may serve as a useful model for the further study of colonic ion transport mechanisms.
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[
"1. An investigation has been carried out into various factors which influence the transmucosal potential difference (p.d.) of rat colon in vivo when the p.d. is either high (> 30 mV) or low (< 20 mV).2. The p.d. was uninfluenced by short duration anaesthesia with ether or pentobarbitone. When anaesthesia was prolonged for several hours, p.d. rose steadily. The gradient of p.d. along the descending colon which developed and its elimination by adrenalectomy suggested that the rise was due to increased secretion of adrenal steroids.3. P.d. was increased by Na depletion after a delay of about 18 hr and fell again following Na repletion with a similar time delay. A characteristic gradient of p.d. along the descending colon was seen.4. Both haemorrhage and anoxia caused a rapid fall of p.d. P.d. was restored rapidly to its previous level when anoxia was corrected.5. Vasopressin (I.V.) in low dose was without effect; in high dose it caused a transient fall of p.d. associated with intense vasoconstriction of gut blood vessels.6. The following factors studied were without effect on p.d.: presence of glucose within the lumen; considerable osmotic gradients across the mucosa; variation of luminal pH over the range 5.2-9.8; intravenous administration of acetazolamide, chlorothiazide, frusemide, triamterene, ethacrynic acid or ouabain. Ouabain in the luminal solution also had no effect in all but two rats in which a small fall of p.d. was seen.7. 2,4-dinitrophenol, 10(-2)M, in the lumen caused a small fall of p.d. only if the p.d. was high.8. Experiments were done to determine the effect on p.d. of altering the ionic composition of the luminal solution. When the p.d. was low (< 20 mV) alteration of [Na], [K] or [Cl] produced small absolute changes of the p.d., all of comparable magnitude. The changes could be interpreted as due to diffusion potentials resulting from the ionic gradients across the mucosa. When the p.d. was high (> 30 mV), it showed a striking dependence on the luminal [Na] only, consistent with the presence of a large p.d. due to active Na transport.",
"1. Using a preparation of rat colon mucosa mounted in vitro in small chambers, some factors which influence the electrical properties of the mucosa have been investigated.2. The mucosa behaved mainly as an ohmic resistance although a very brief transient occurred on first passing current. At 32 degrees C, the fresh preparation had a mean resistance of 108Omega/cm(2) and a mean short circuit current (s.c.c.) of 143 muA/cm(2). Tissues taken from Na-depleted and adrenalectomized rats differed little from normal tissues in electrical resistance but those from Na-depleted rats had higher potential difference (p.d.) and s.c.c.3. Increase of temperature led to a rise of conductance of similar order to that found for ions in aqueous solution. S.c.c. also rose with increase of temperature but the effect was relatively greater consistent with its being dependent on metabolic processes.4. Anoxia or the addition of cyanide, iodoacetate or 2,4-dinitrophenol to the bath fluid caused considerable fall in the p.d. and s.c.c.5. Ouabain decreased the p.d. and s.c.c. when added to the serosal side but had no effect when on the luminal side.6. Aldosterone and acetazolamide had no effect.7. Varying serosal side [K] produced only minor changes in p.d.8. Reducing [Na] of the luminal solution caused a considerable fall of p.d. but similar reduction of [Na] on the serosal side had little effect.9. The frequently employed model which represents the transepithelial p.d. as the sum of diffusion potentials originating at the luminal and serosal sides of the cell layer is not consistent with the present results. The colonic transmucosal p.d. probably originates in the electrogenic transport of Na by a mechanism located on the serosal side of the epithelium.",
"Interrelationships among Na, Cl, and HCO3 transport processes were examined in short-circuited rabbit ileal mucosa. As serosal (HCO3) was increased from 10 to 50 mM (pH from 7.1 to 7.8), net Na absorption decreased from 4.6 to 0.3 mueq/h-cm2, net Cl flux changed from absorption of 0.9 to secretion of 0.9 and a net HCO3 secretion of 3.0 developed. A similar change in net Cl flux was also observed when serosal Pco2 was altered at constant (HCO3). In Cl-free SO4-Ringer, serosal alkalinization produced net HCO3 secretion which was not significantly less than that observed in Cl-containing Ringer. Theophylline caused secretory changes in net Na and Cl fluxes at both 10 and 50 mM serosal (HCO3). Theophylline did not alter net HCO3 flux in Cl-Ringer but increased net HCO3 flux in SO4-Ringer. Total dc conductance was decreased by both serosal alkalinization and theophylline. Shortcircuit current was consistently increased by theophylline but not by serosal alkalinization. The results indicate that ileal ion transport is regulated in part by serosal pH and/or (HCO3) and that resulting changes in Cl and HCO3 transport are coupled one-for-one with changes in Na transport. Furthermore, HCO3 secretion does not require the presence of Cl in the bathing medium."
] |
Structural evidence that SV40 virus is prevented from exiting the nucleus
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SV40 particles can apparently enter the nucleus intact. However, they do not leave the nucleus despite the high concentration present during the productive phase. We found structural evidence that SV40 virus is prevented from approaching the most likely site of exit, the nuclear pore complex. From these images, it is concluded that the fibrils attached to the nuclear pore complex prevent egress of SV40 particles from the infected nucleus.
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[
"Epoxy embedding methods of Glauert and Kushida have been modified so as to yield rapid, reproducible, and convenient embedding methods for electron microscopy. The sections are robust and tissue damage is less than with methacrylate embedding.",
"Kidney cells, predominantly from Cercopithecus monkeys but also from baboons, were infected in vitro with the SV40 virus. The infectious cycle was studied with the electron microscope by means of thin sections of cells fixed from 3 hours up to 11 days after infection. The frequency of virus formation and various nuclear and cytoplasmic lesions in relation to the infection are described. The virus particles appear in the nucleus in close contact with the chromatin. In a small number of cells they have been observed as early as 10 to 12 hours after infection, but most often they appear 24 to 48 hours afterward. Their mean diameter is 33 mmicro. They have no membrane and are frequently arranged as crystal-like structures. In addition to the appearance of virus, one observes various lesions in the nucleoplasm and particularly in the nucleolus, which shows an early hypertrophy and produces unusual, dense condensations in contact with the nucleolonema. The importance of these nucleolar lesions and the relationship between the SV40 virus and the polyoma, common wart, and Shope papilloma viruses are discussed.",
"Nuclear pore complexes have been isolated in association with a 150 A thick lamina by detergent and salt fractionation of nuclear envelopes from rat liver. The pore complexes exhibit characteristic morphology and appear to be attached in a highly specific orientation to the lamina, which extends over relatively large areas. The pore complex-lamina fraction is composed of three major and several minor polypeptides with little or no DNA, RNA, or phospholipid. It is suggested that the association of the pore complexes and the lamina reflects the structural arrangement of the nuclear periphery in vivo."
] |
In vitro inhibition of HeLa cell protein synthesis by poliovirus.
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The inhibition of HeLa cell protein synthesis by poliovirus was studied by examining initiation in vitro on endogenous host polyribosomes. At an early stage, before major viral RNA replication and protein synthesis begins, the initiation of translation on cellular mRNA is strongly inhibited. Fractionation of extracts from infected cells shows that the lesion is associated mainly with the crude polyribosome fraction. The cellular mRNA appears unchanged and is as active as mRNA from control cells in stimulating incorporation. The native ribosomal subunits and KCl-washed polyribosomes from the infected cells are also active. Only the ribosomal wash fraction prepared from the inhibited polyribosomes had reduced activity. However, the reduction in the ribosomal wash activity measured in a reconstructed system is not as large as the inhibition seen with "native" polyribosomes. The results indicate that a viral induced inhibition is probably associated with the ribosomal wash fraction, but the reconstructed system is not equivalent to the "native" inhibited system.
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[
"Eukaryotic cells contain polypeptide chain initiation factors that, like the prokaryotic initiation factor IF-2, promote the AUG-dependent binding of fMet-tRNA(f) to the small ribosomal subunit. The bound amino-acyl-tRNA is directly convertible to fMet-puromycin upon addition of 60S subunit. The reaction is sensitive to initiation inhibitors such as aurintricarboxylic acid and edeine but, unlike its prokaryotic counterpart, it does not require GTP. Factors that catalyze the binding and fMet-puromycin reactions with ribosomal subunits from Artemia salina embryos are present in postribosomal supernatants of Artemia, mouse fibroblasts (L cells), and rat liver, as well as in salt washes of rabbit reticulocyte ribosomes. However, whereas all three supernatant factors, like Escherichia coli IF-2, are sensitive to SH-binding reagents, the reticulocyte factor is not. The rat liver and Artemia factors function indiscriminately with Artemia or rat liver ribosomes, but the Artemia factor and E. coli initiation factor IF-2 are not interchangeable.",
"The native small ribosomal subunit (Sn) from rabbit reticulocytes which is able to initiate translation of globin mRNA in a cell-free system carries additional protein components. The latter can be separated from the subunit in a high salt sucrose gradient yielding a top fraction (T) and a complex fraction (C), sedimenting at about 4 and 15 S, respectively. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate revealed that fraction T contained four dominant polypeptides, while fraction C represents a large protein complex consisting of at least 10 polypeptides. Sn isolated from other sources showed similar patterns of their nonribosomal proteins. Reconstitution experiments revealed that fraction C is absolutely required for protein synthesis, while fraction T enhances protein synthesis only in the presence of C. The adherence of these protein factors to the subunit is not mediated by magnesium ions. Treatment of Sn with EDTA and centrifugation in a magnesium-free sucrose gradient caused unfolding of the subunits and dissociation of several ribosomal proteins, but not of the factors. The unfolded ribosomal subunits sedimented as two distinct peaks. The more slowly sedimenting peak contained proteins of fraction T and the faster sedimenting one contained the 15S complex, indicating heterogeneity of the Sn population with respect to the factors attached to them.",
"Embryos of the brine shrimp, Artemia salina, were used in a study of polypeptide chain initiation in an in vitro system from a eukaryote. A protein, isolated from the high-speed supernatant, has been highly purified and shown to have properties that suggest it is the eukaryotic equivalent of the Escherichia coli initiation factor F(2): It promotes the AUG-dependent binding of fMet-tRNA (E. coli) to the Artemia 40S ribosomal subunit, but not to either the 60S or 80S species; the bound fMet-tRNA is placed in a site on the smaller subunit from which it reacts with puromycin upon addition of the 60S subunit; and the activity is sensitive to aurintricarboxylic acid and edeine, specific inhibitors of initiation. The factor, a basic protein of molecular weight about 100,000, is inactivated by N-ethylmaleimide, an SH-binding reagent, and is clearly distinct from the Artemia elongation factors, T(1) and T(2). In addition, the factor stimulates the poly(U)-dependent binding of Phe-tRNA (E. coli) to the Artemia 40S ribosomal subunit. This reaction, though similar to the fMet-tRNA-binding reaction, differs in that the bound Phe-tRNA is largely resistant to release by puromycin."
] |
Immunomodulatory cancer therapy: a review of informatics techniques.
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The rapid development of immunomodulatory cancer therapies has led to a concurrent increase in the application of informatics techniques to the analysis of tumors, the tumor microenvironment, and measures of systemic immunity. In this review, the use of tumors to gather genetic and expression data will first be explored. Next, techniques to assess tumor immunity are reviewed, including HLA status, predicted neoantigens, immune microenvironment deconvolution, and T-cell receptor sequencing. Attempts to integrate these data are in early stages of development and are discussed in this review. Finally, we review the application of these informatics strategies to therapy development, with a focus on vaccines, adoptive cell transfer, and checkpoint blockade therapies.
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[
"Immunologic checkpoint blockade with antibodies that target cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and the programmed cell death protein 1 pathway (PD-1/PD-L1) have demonstrated promise in a variety of malignancies. Ipilimumab (CTLA-4) and pembrolizumab (PD-1) are approved by the US Food and Drug Administration for the treatment of advanced melanoma, and additional regulatory approvals are expected across the oncologic spectrum for a variety of other agents that target these pathways. Treatment with both CTLA-4 and PD-1/PD-L1 blockade is associated with a unique pattern of adverse events called immune-related adverse events, and occasionally, unusual kinetics of tumor response are seen. Combination approaches involving CTLA-4 and PD-1/PD-L1 blockade are being investigated to determine whether they enhance the efficacy of either approach alone. Principles learned during the development of CTLA-4 and PD-1/PD-L1 approaches will likely be used as new immunologic checkpoint blocking antibodies begin clinical investigation.",
"Multiple investigators have reported the presence of defects in the immune response of the elderly [Castle In: Clin Infect Dis 31:578, 2000; Ortqvist et al. In: Eur Respir J 30:414-422, 2007; Saurwein-Teissl et al. In: J Immunol 168:5893, 2002; Haynes et al. In: Proc Natl Acad Sci USA 100:15053-15058, 2003]. These defects reduce the magnitude of the immune response to infection and to vaccination. In individuals greater than 55 years of age, the probability of developing a fully protective neutralizing antibody response to the yearly multivalent particle inactivated influenza vaccine is less than 20% [Jefferson et al. In: Lancet 264:1165-1174, 2005; Goodwin et al. In: Vaccine 24:1159-1169, 2006; Jackson et al. In: Lancet 372:398-405, 2008; Simonsen and Taylor In: Lancet 7:658-666, 2007]. The defects in the aged immune system that are responsible for this limited response to vaccination in the older age groups include functional defects of the antigen presenting cells, functional defects in CD4 helper CD4 T cells and monocytes, and an altered microenvironment [Eaton et al. In: J Exp Med 200:1613-1622, 2004; Dong et al. In: J Gen Virol 84:1623-1628, 2003; Deng et al. In: Immunology 172:3437-3446, 2004; Cella et al. In: J Exp Med 184:747-752, 1996]. Starting at puberty, the involution of the thymus and the consequent reduction of the export of naïve T cells specific to neo-antigens leads to the reduction of the ratio of antigen naïve to memory cells as chronological age advances [Prelog In: Autoimmun Rev 5:136-139, 2006; McElhaney et al. In: J Immunology 176:6333-6339, 2006]. Changes in glycosylation of T cells and target antigens acquired during the aging process and the antibodies to these new glycopeptides and glycoproteins may also contribute to a reduction in the functioning of the adaptive immune response [Ishii et al. In: J Clin Neurosci 14:110-115, 2007; Shirai et al. In: Clin Exp Immunol 12:455-464, 1972; Adkins and Riley In: Mech Ageing Dev 103:147-164, 1998; Ben-Yehuda and Weksler In: Cancer Investigation 10:525-531, 1992]. One of the more interesting examples of the functional defects in the cells of the adaptive immune response is a reduced level of expression in the surface cytoadhesion and activation receptor molecules on CD4 helper T cells undergoing activation during vaccination. Upon infection or vaccination, CD40L is typically increased on the surface of CD4 helper T cells during activation, and this increased expression is absolutely essential to the CD40L promotion of expansion of antigen-specific B cells and CD 8 effector T cells in response to infection or vaccination [Singh et al. In: Protein Sci 7:1124-1135, 1998; Grewal and Flavell In: Immunol Res 16: 59-70, 1997; Kornbluth In: J Hematother Stem Cell Res 11:787-801, 2002; Garcia de Vinuesa et al. In: Eur J Immunol 29:3216-3224, 1999]. In aged human beings and mice, the reduced levels of expression of CD40 ligand (CD40L) in activated CD4 helper T cells is dramatically reduced [Eaton et al. In: J Exp Med 200:1613-1622, 2004; Dong et al. In: J Gen Virol 84:1623-1628, 2003]. To circumvent the reduction in CD40L expression and the subsequent reduction in immune response in the elderly, we have developed a chimeric vaccine comprised of the CD40L linked to the target antigen, in a replication incompetent adenoviral vector and in booster protein. This review will discuss the implementation the potential use of this approach for the vaccination of the older populations for cancer and infection.",
"Given the vast number of genetic and epigenetic changes associated with carcinogenesis, it is clear that tumors express many neoantigens. A central question in cancer immunology is whether recognition of tumor antigens by the immune system leads to activation (i.e., surveillance) or tolerance. Paradoxically, while strong evidence exists that specific immune surveillance systems operate at early stages of tumorigenesis, established tumors primarily induce immune tolerance. A unifying hypothesis posits that the fundamental processes of cancer progression, namely tissue invasion and metastasis, are inherently proinflammatory and thus activating for innate and adaptive antitumor immunity. To elude immune surveillance, tumors must develop mechanisms that block the elaboration and sensing of proinflammatory danger signals, thereby shifting the balance from activation to tolerance induction. Elucidation of these mechanisms provides new strategies for cancer immunotherapy.",
"Most cancers emerge in elderly and immune-comprised hosts implying an important role for cancer immune surveillance. Here, we focus on the role of tissue-associated innate immune cells including antigen presenting cells (i.e. dendritic cells and macrophages), myeloid derived suppressor cells and neutrophils in healthy and cancer-bearing elderly hosts. Most cancers, including the cancers that we are interested in, i.e. lung carcinomas and mesothelioma, emerge in aging populations at a time when naïve T cell function is declining. CD8(+) cytotoxic T lymphocytes are critical anti-tumor effector cells, and their diminished function may contribute to cancer escape mechanisms in the elderly. Therefore, we compare the likely consequences of innate immune cell interactions with T cells in young versus elderly hosts. We examine data showing that elderly-derived innate cells are highly immunosuppressive and may provide a more tumorigenic milieu than their younger counterparts. Standard chemotherapy often only provides these patients a few extra months survival time. Recent evidence has shown that standard chemotherapy is not as effective in hosts devoid of T cells. Therefore, T cell dysfunction in the elderly may contribute to poor treatment outcomes. However, there is also evidence that T cell immunity can be rejuvenated via activated dendritic cells and/or macrophages. Combining 'rejuvenation' immunotherapy with standard chemotherapy may offer an improved outcome for elderly cancer patients. We explore this potential herein.",
"The capacity of immunity to control and shape cancer, that is, cancer immunoediting, is the result of three processes that function either independently or in sequence: elimination (cancer immunosurveillance, in which immunity functions as an extrinsic tumour suppressor in naive hosts); equilibrium (expansion of transformed cells is held in check by immunity); and escape (tumour cell variants with dampened immunogenicity or the capacity to attenuate immune responses grow into clinically apparent cancers). Extensive experimental support now exists for the elimination and escape processes because immunodeficient mice develop more carcinogen-induced and spontaneous cancers than wild-type mice, and tumour cells from immunodeficient mice are more immunogenic than those from immunocompetent mice. In contrast, the equilibrium process was inferred largely from clinical observations, including reports of transplantation of undetected (occult) cancer from organ donor into immunosuppressed recipients. Herein we use a mouse model of primary chemical carcinogenesis and demonstrate that equilibrium occurs, is mechanistically distinguishable from elimination and escape, and that neoplastic cells in equilibrium are transformed but proliferate poorly in vivo. We also show that tumour cells in equilibrium are unedited but become edited when they spontaneously escape immune control and grow into clinically apparent tumours. These results reveal that, in addition to destroying tumour cells and sculpting tumour immunogenicity, the immune system of a naive mouse can also restrain cancer growth for extended time periods.",
"Immunotherapy is now experiencing unprecedented successes in treating various cancers based on new understandings of cancer immunopathogenesis. Nonetheless, although ageing is the biggest risk factor for cancer, the majority of cancer immunotherapy preclinical studies are conducted in young hosts. This review will explore age-related changes in immunity as they relate to cancer immune surveillance, immunopathogenesis and responses to immunotherapy. Although it is recognized that declining T cell function with age poses a great challenge to developing effective age-related cancer immunotherapies, examples of successful approaches to overcome this hurdle have been developed. Further, it is now recognized that immune functions do not simply decline with age, but rather change in ways than can be detrimental. For example, with age, specific immune cell populations with detrimental functions can become predominant (such as cells producing proinflammatory cytokines), suppressive cells can become more numerous or more suppressive (such as myeloid-derived suppressor cells), drugs can affect aged immune cells distinctly and the aged microenvironment is becoming recognized as a significant barrier to address. Key developments in these and other areas will be surveyed as they relate to cancer immunotherapy in aged hosts, and areas in need of more study will be assessed with some speculations for the future. We propose the term 'age-related immune dysfunction' (ARID) as best representative of age-associated changes in immunity.",
"Immune responses involve coordination across cell types and tissues. However, studies in cancer immunotherapy have focused heavily on local immune responses in the tumor microenvironment. To investigate immune activity more broadly, we performed an organism-wide study in genetically engineered cancer models using mass cytometry. We analyzed immune responses in several tissues after immunotherapy by developing intuitive models for visualizing single-cell data with statistical inference. Immune activation was evident in the tumor and systemically shortly after effective therapy was administered. However, during tumor rejection, only peripheral immune cells sustained their proliferation. This systemic response was coordinated across tissues and required for tumor eradication in several immunotherapy models. An emergent population of peripheral CD4 T cells conferred protection against new tumors and was significantly expanded in patients responding to immunotherapy. These studies demonstrate the critical impact of systemic immune responses that drive tumor rejection.",
"Immune checkpoint inhibitors, which unleash a patient's own T cells to kill tumors, are revolutionizing cancer treatment. To unravel the genomic determinants of response to this therapy, we used whole-exome sequencing of non-small cell lung cancers treated with pembrolizumab, an antibody targeting programmed cell death-1 (PD-1). In two independent cohorts, higher nonsynonymous mutation burden in tumors was associated with improved objective response, durable clinical benefit, and progression-free survival. Efficacy also correlated with the molecular smoking signature, higher neoantigen burden, and DNA repair pathway mutations; each factor was also associated with mutation burden. In one responder, neoantigen-specific CD8+ T cell responses paralleled tumor regression, suggesting that anti-PD-1 therapy enhances neoantigen-specific T cell reactivity. Our results suggest that the genomic landscape of lung cancers shapes response to anti-PD-1 therapy.",
"Therapeutic vaccines represent a viable option for active immunotherapy of cancers that aim to treat late stage disease by using a patient's own immune system. The promising results from clinical trials recently led to the approval of the first therapeutic cancer vaccine by the U.S. Food and Drug Administration. This major breakthrough not only provides a new treatment modality for cancer management but also paves the way for rationally designing and optimizing future vaccines with improved anticancer efficacy. Numerous vaccine strategies are currently being evaluated both preclinically and clinically. This review discusses therapeutic cancer vaccines from diverse platforms or targets as well as the preclinical and clinical studies employing these therapeutic vaccines. We also consider tumor-induced immune suppression that hinders the potency of therapeutic vaccines, and potential strategies to counteract these mechanisms for generating more robust and durable antitumor immune responses.",
"This study describes the construction of soluble major histocompatibility complexes consisting of the mouse class I molecule, H-2Db, chemically biotinylated beta2 microglobulin and a peptide epitope derived from the glycoprotein (GP; amino acids 33-41) of lymphocytic choriomeningitis virus (LCMV). Tetrameric class I complexes, which were produced by mixing the class I complexes with phycoerythrin-labeled neutravidin, permitted direct analysis of virus-specific cytotoxic T lymphocytes (CTLs) by flow cytometry. This technique was validated by (a) staining CD8+ cells in the spleens of transgenic mice that express a T cell receptor (TCR) specific for H-2Db in association with peptide GP33-41, and (b) by staining virus-specific CTLs in the cerebrospinal fluid of C57BL/6 (B6) mice that had been infected intracranially with LCMV-DOCILE. Staining of spleen cells isolated from B6 mice revealed that up to 40% of CD8(+) T cells were GP33 tetramer+ during the initial phase of LCMV infection. In contrast, GP33 tetramers did not stain CD8+ T cells isolated from the spleens of B6 mice that had been infected 2 mo previously with LCMV above the background levels found in naive mice. The fate of virus-specific CTLs was analyzed during the acute phase of infection in mice challenged both intracranially and intravenously with a high or low dose of LCMV-DOCILE. The results of the study show that the outcome of infection by LCMV is determined by antigen load alone. Furthermore, the data indicate that deletion of virus-specific CTLs in the presence of excessive antigen is preceded by TCR downregulation and is dependent upon perforin."
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A simple assay for cholera enterotoxin in Chinese hamster ovary cells
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A new, simple assay method using Chinese hamster ovary cells was devised for cholera enterotoxin. The effect of the cholera toxin was measured by an increase in cell adhesion to the substratum. The increase was dependent on the concentration of the toxin used and was effective for a longer period of time than that of adhesion increased by dibutyryl cyclic adenosine monophosphate and theophyline. There was a delay of about 60 min before the increase in adhesion, using the toxin, appeared, whereas the increase caused by dibutyryl cyclic adenosine monophosphate appeared almost at once.
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[
"Natural cholera toxoid appears to act as a competitive inhibitor of cholera enterotoxin and is thus a useful tool for studying the interaction of cholera enterotoxin with cell membranes. Cholera enterotoxin binds to gut mucosa more rapidly than does its natural toxoid. Once binding occurs, however, it appears to be prolonged for both materials. Formalinized cholera toxoid has no inhibitory effect upon cholera enterotoxin. Enterotoxic activity, ability to bind to gut mucosa, and antitoxigenicity appear to be independent properties of cholera enterotoxin. Natural cholera toxoid does not inhibit Escherichia coli enterotoxin, indicating that although the two enterotoxins activate the same mucosal secretory mechanism they occupy different binding sites in the mucosa. Ganglioside, which may be the mucosal receptor of cholera enterotoxin, is highly efficient in deactivating cholera enterotoxin. By contrast, ganglioside is relatively inefficient in deactivating heat-labile E. coli enterotoxin and is without effect upon the heat-stable component of E. coli enterotoxin. These findings suggest that ganglioside is not likely to be the mucosal receptor for E. coli enterotoxin. Differences in cellular binding of E. coli and cholera enterotoxins may explain, at least in part, the marked differences in the time of onset and duration of their effects upon gut secretion.",
"A heat-labile factor in cell-free filtrate of a Vibrio cholerae culture induces a marked rise in the wet-weight concentration of adenosine 3':5'-cyclic monophosphate (cyclic AMP) in the intestinal mucosa of the dog. The increase becomes appreciable 1-1.5 hr after intraluminal administration of the filtrate, about the same time as the onset of intestinal secretion in response to a heat-labile enterotoxin in the filtrate. These results are consistent with the hypothesis that cyclic AMP may be an intermediary in the intestinal secretory response to cholera toxin.",
"Secondary cultures of human diploid fibroblasts, which demonstrate density-dependent inhibition of cell growth, were used to study the effect of adenosine 3'-5'-cyclic monophosphate (cAMP) on cell proliferation. DNA synthesis in nonconfluent cultures and in contact-inhibited cultures stimulated to grow by refeeding with fresh medium was found to be inhibited by exogenous cAMP. The properties of this inhibition of DNA synthesis, together with the alterations in cAMP metabolism observed in confluent cultures of cells stimulated with fresh medium to resume growth, strongly suggest that cAMP is involved in contact-inhibition of cell proliferation.",
"Choleragen, the pure protein from cholera toxin, stimulates steroid secretion by Y-1 adrenal tumor cells in culture. The secreted steroids are the same as seen after addition of adrenocorticotropic hormone. Half-maximal stimulation occurs at 15 pM; stimulation is essentially irreversible by washing and partially reversible (for about 1 hr) by antibody, and there is a latent period of about 60 min before stimulation is seen. Stimulation of adenylate cyclase occurs at about 30-fold higher choleragen concentrations. Gangliosides inhibit choleragen stimulation when added before but not after the toxin. Lipopolysaccharides from Escherichia coli, Salmonella typhosa, and Serratia marcescens also stimulate steroid secretion, but are less potent than choleragen.",
"Epidermal growth factor (EGF) stimulates both DNA and RNA synthesis in contact-inhibited human fibroblasts. Stimulation of DNA synthesis is observed at concentrations as low as 3 pM, is half-maximal at 70 pM, and is maximal at 300 pM EGF. The action of EGF is similar to that of fetal-calf serum, but is distinguished by the time-course of stimulation and by the ability of serum to stimulate further those cells maximally stimulated by EGF. Cells that synthesize DNA in response to physiological concentrations of EGF (10(-11) to 10(-10) M) are insensitive to physiological concentrations of insulin (10(-11) to 10(-10) M) and respond only minimally to very high concentrations of this hormone (10(-6) M). The biological activity of EGF is paralleled by binding of this peptide to fibroblasts in a specific and saturable manner; the dissociation constant is about 800 pM. The binding of EGF is unaffected by either insulin or cholera toxin. Cholera toxin inhibits the action of both EGF and serum. Suppression of DNA synthesis is observed at 0.02 pM toxin, and is maximal at about 2 pM. Cells treated with cholera toxin at these concentrations appear to be otherwise viable by several criteria. The stimulatory effects of EGF are also inhibited by theophylline and dibutyryl cyclic AMP separately or in combination. These observations indicate that fibroblasts possess receptors for EGF by biological and physicochemical criteria, and suggest that a similar if not identical peptide may be amongst those factors in sera which stimulate cell growth. The possibility is considered that EGF and cholera toxin modulate the ability of a cell to initiate polynucleotide synthesis by way of specific cell-surface interactions which in turn alter the levels of intracellular cyclic AMP.",
"Cholera toxin (choleragen) and melanocyte stimulating hormone alter within hours the morphology of melanoma cells in culture, and they slow the growth of serum-stimulated cells. After 7-10 days, cells exposed to choleragen or hormone show increased size and a fibroblastic growth pattern. Tyrosinase (EC 1.14.18.1; monophenol monooxygenase) activity increases after 3 days in the presence of 10(-8) M hormone or 10(-10) M choleragen. Binding studies with (125)I-labeled choleragen indicate that although a melanoma cell can bind a maximum of 10(6) molecules of cholera toxin, only about 4000 binding sites must be occupied to achieve maximum stimulation of tyrosinase activity. Melanocyte stimulating hormone and choleragen probably have different membrane-binding sites. After exposure to choleragen for 5 min, membrane adenylate cyclase (EC 4.6.1.1) activity increases dramatically upon further incubation of intact cells for several hours at 37 degrees and falls slowly to basal values over a period of more than 10 days. Hormone stimulation of adenylate cyclase is rapidly reversed by washing the cells, but subsequent restimulation of cyclase by the hormone is impaired. These studies indicate that cAMP mediates the effects of melanocyte stimulating hormone on growth and morphology as well as on tyrosinase activity. Cholera toxin may permanently activate the available adenylate cyclase molecules, and the protracted decay of stimulation that follows may reflect the biological turnover of adenylate cyclase molecules in these cells."
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Nucleic acid hybridization of xenotropic murine type C viruses
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Two major subclasses of xenotropic (X-tropic) murine type C viruses can be distinguished by nucleic acid hybridization. The most frequently encountered subclass (MuLV-X-alpha) includes isolates from BALB/c, C57BL/6J, C58/J, AKR/J, CBA/J, and DBA/2J inbred strains and from the Asian feral mouse subspecies Mus musculus molossinus. The other subclass (MuLV-X-beta) consists of viruses isolated from the NIH Swiss and NZB/BINJ strains. Thus, significant polymorphism exists among the endogenous type C virogenes of a single species, Mus musculus. MuLV-X-alpha genes are found in strains that also have endogenous mouse-tropic viruses (either N-tropic, B-tropic, or both), whereas the MuLV-X-beta subclass is restricted to mouse strains from which mouse-tropic viruses have not yet been isolated. The results are consistent with a model which proposes that mouse-tropic endogenous viruses are derived from the MuLV-X-alpha subclass.
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"The transmission of murine leukemia virus (MLV) to hybrids between AKR and Fv-1(b) mice was studied in order to evaluate the effect of the Fv-1 gene on endogenous MLV infection and to attempt to determine if the genetic loci contributed by AKR carry viral genetic determinants. Fv-1 was shown to have a marked suppressive effect on time of appearance of detectable infectious virus and on the titers attained in vivo, but did not affect the ability of the cells to produce virus in vitro after induction with 5-iododeoxyuridine. The host range type of the virus detected in the hybrid mice was almost always of the type carried by AKR, although the low-virus Fv-1(b) parents carry the genome of a different host range type. This finding provides strong, but not conclusive, evidence that the virus-inducing loci of AKR contain MLV genetic determinants.",
"Kinetic analysis of the reassociation of DNA synthesized in vitro by a murine leukemia virus DNA polymerase revealed two classes of double-stranded product representative of 25 and 100 percent of viral genetic information. The DNA product representing the smaller portion of the viral genome comprised 85 percent of the double-stranded DNA generated in vitro and was extensively duplicated in the genomes of both normal cells and cells containing RNA tumor virus.",
"The AKR mouse has a high titer of murine leukemia virus early in life, and virus-negative cells derived from embryos of this mouse strain can be activated to yield murine leukemia virus by treatment with 5-iododeoxyuridine. In contrast to this high-virus strain, the NIH Swiss mouse has a low incidence of leukemia and no murine leukemia virus has been isolated from it (virus-negative). We have investigated this difference between AKR and NIH mice by examining the sequences specific for murine leukemia virus in nucleic acids of these mice. A single-stranded viral-DNA probe synthesized in vitro using murine-leukemia-virus from the AKR mouse contains at least 87% of the sequences present in the 70S viral RNA; most of these sequences are in proportions similar to their content in the 70S RNA. Using this probe in nucleic acid hybridization experiments, we have shown that NIH-mouse-cell DNA and AKR-mouse-cell DNA differ with respect to sequences specific for AKR murine-leukemia-virus: NIH-mouse-cell DNA lacks some of the virus-specific sequences present in AKR-mouse-cell DNA, and there are two distinct sets of virus-specific sequences in AKR-mouse-cell DNA, whereas there is only one set in NIH-mouse-cell DNA.RNA from virus-negative AKR-mouse cells grown in tissue culture contains some, but not all, virus-specific RNA sequences; however, within 48 hr after initiating treatment of these cells with 5-iododeoxyuridine, the complete viral genome is represented in cellular RNA."
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Mechanisms of zeiosis in epithelial cells
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The projection of knobby protuberances at the cell surface (zeiosis) is a general cellular response to cytochalasin D (CD), resulting from herniation of endoplasm through undefended places of the cortex during cell contractions and displacement of microfilaments induced by CD. Zeiosis is prevented by agents that interfere with the contractile response to CD, such as inhibitors of energy metabolism or cyclic AMP. The developed protrusions, which remain relatively stable in the presence of CD, contain chiefly mono- or subribosomes, and occasionally other organelles normally resident in endoplasm; compact microfilament felt occupies their bases and extends into their proximal stalks. Protein synthesis in the knobs is less than half of that in the polyribosome-containing endoplasm residual in the main body of the cell. Knobs first protrude singly near the margin of the contracting cells and rapidly cluster into small groups in the periphery even at lower temperature. The clusters then migrate centripetally and coalesce into a large aggregate near the apex of the immobilized and retracted cell: this movement is energy- and temperature-dependent. Aggregation is more prominent and stable in cell lines of epithelial derivation than in fibroblastic or other lines in which nuclear extrusion occurs more readily. The latter is regarded as a special manifestation of zeiosis. Macromarkers, such as latex spherules, migrate like the zeiotic knobs on the cell surfaces in the presence of CD. The aggregated knobs, although persistent for days in the presence of CD, are rapidly recessed after withdrawal of the agent as ruffling is resumed and the cells spread. These movements are discussed in terms of current concepts of mobility of the cell membrane.
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"An in vitro system was used to test the purported action of cytochalasin B. At concentrations 100 times those used for experiments in vivo, cytochalasin B did not cause the breakdown of F-actin, did not inhibit the transformation of G-actin to F-actin, did not inhibit the binding of heavy meromyosin to F-actin, and did not inhibit the adenosine triphosphate-induced release of heavy meromyosin from F-actin.",
"The first manifestation of reverse transformation, in which a permanent epithelial-like cell is reversibly transformed into a fibroblast-like cell by dibutyryl adenosine cyclic 3':5'-monophosphate, is the disappearance of a set of violently extending and retracting knobbed structures on the cell membrane with consequent tranquilization of the membrane. The cell then elongates to assume a fibroblast-like morphology. Permanently fibroblast-like cells, which have smooth membranes, can be changed into knobbed epithelial-like cells by the addition of either colcemid or cytochalasin B, agents that disorganize one or the other component, respectively, of the microtubular-microfibrillar system. Permanently smoothmembraned, epithelial-like cells also become knobbed by such treatment. All of these knobbed epithelial-like cells can be converted into smooth-membraned fibroblast-like cells by dibutyryl cAMP alone or with the aid of supporting molecules like testosterone. It is proposed that these are general phenomena and that the knobbed epithelial-like forms and the more highly differentiated smooth-membraned fibroblast-like cells represent extreme situations with respect to the degree of organization of the microtubular-microfibrillar system inside the cell.",
"HeLa, Vero, L, HEp2, and MDBK cells respond immediately to 0.2-0.5 microg/ml cytochalasin D (CD) with sustained contraction (contracture), loss of microvilli, expression of endoplasmic contents (zeiosis), nuclear protrusion, and extension of cytoplasmic processes. The development of these changes is depicted, and the dose-response patterns in these cell lines are described. MDBK is generally most resistant and HeLa most sensitive to these effects of CD. Cells in G(1) are most sensitive to CD; responsiveness decreases progressively during early S and is least in mid S through G(2). CD inhibits transport of [(14)C]deoxyglucose in HeLa by about 45% but has no significant effect on hexose uptake in Vero and MDBK; sugar transport is thus apparently unrelated to any morphologic effect of CD. Although spreading and attachment are impeded, CD does not decrease and may even enhance the adhesiveness of established monolayers. Contraction appears to be a primary early effect of CD, upon which other visible changes follow. It is prevented by some inhibitors of energy metabolism (deoxyglucose and dinitrophenol) and does not occur in glycerinated models without ATP. The possible bases of the contractile response to CD are discussed. Although direct or indirect action of CD on some microfilaments may occur, a generalized structural disruption of contractile filaments by CD is considered unlikely.",
"Platelet myosin (thrombosthenin M) and two additional proteins corresponding to the head and rod portion of the myosin molecule have been prepared from human blood platelets. Characterization of these proteins by SDS-polyacrylamide gel electrophoresis, actin binding studies, assay of enzymic ATPase activity, and electron microscopy has shown that the platelet contractile proteins closely resemble the corresponding muscle proteins. Platelet myosin and platelet myosin-head bind to both muscle and platelet actin and have an EDTA + K-stimulated ATPase activity, which is suppressed by Mg(2+) in high salt concentration, whereas platelet rod does not possess either of these properties; platelet myosin and platelet myosin rod aggregate to form thick filaments at low ionic strength. Both intact platelet myosin and myosin head form typical arrowhead-shaped complexes with either platelet or muscle F-actin."
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Structure of the M intermediate in bacteriorhodopsin
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Structural changes are central to the mechanism of light-driven proton transport by bacteriorhodopsin, a seven-helix membrane protein. The main intermediate formed upon light absorption is M, which occurs between the proton release and uptake steps of the photocycle. To investigate the structure of the M intermediate, we have carried out electron diffraction studies with two-dimensional crystals of wild-type bacteriorhodopsin and the Asp96-->Gly mutant. The M intermediate was trapped by rapidly freezing the crystals in liquid ethane following illumination with a xenon flash lamp at 5 and 25 degrees C. Here, we present 3.5 A resolution Fourier projection maps of the differences between the M intermediate and the ground state of bacteriorhodopsin. The most prominent structural changes are observed in the vicinity of helices F and G and are localized to the cytoplasmic half of the membrane.
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"We report that the replacement of Leu-93 in bacteriorhodopsin by Ala (L93A) or Thr (L93T) slows down the photocycle by approximately 100-fold relative to wild-type bacteriorhodopsin. Time-resolved visible absorption spectroscopy and resonance Raman experiments, respectively, show the presence of long-lived O-like and N-like intermediates in the photocycles of the above mutants. We infer the existence of an equilibrium between the N and O intermediates in the photocycles of these mutants. The L93A and L93T mutants exhibit normal proton pumping under continuous illumination, suggesting that the decay of the N and/or O intermediate, and consequently, proton translocation, can be accelerated by the absorption of a second photon. Since the 13-cis----all-trans reisomerization of retinal is completed during the decay of the N and O intermediates, we conclude that the interaction of Leu-93 with retinal is important in this phase of the photocycle. This conclusion is supported by a recent structural model of bacteriorhodopsin that suggests that Leu-93 is near the C-13 methyl group of retinal.",
"A nanosecond resolution laser-driven x-ray source has been used to perform a time-resolved, x-ray diffraction study of the purple membrane of the Halobacterium halobium. Alterations in diffraction patterns have been observed 1 ms after photostimulation, and are interpreted to show disorder of bacteriorhodopsin packing in the plane of the membrane with little bacteriorhodopsin structural change.",
"A spectroscopic and functional analysis of two point-mutated bacteriorhodopsins (BRs) from phototrophic negative halobacterial strains is reported. Bacteriorhodopsin from strain 384 contains a glutamic acid instead of an aspartic acid at position 85 and BR from strain 326 contains asparagine instead of aspartic acid at position 96. Compared to wild-type BR, the M formation in BR Asp85---Glu is accwelerated approximately 10-fold, whereas the M decay in BR Asp96---Asn is slowed down approximately 50-fold at pH6. Purple membrane sheets containing the mutated BRs were oriented and immobilized in polyacrylamide gels or adsorbed to planar lipid films. The measured kinetics of the photocurrents under various conditions agree with the observed photocycle kinetics. The ineffectivity of BR Asp85---Glu resides in the dominance of an inactive species absorbing maximally at approximately 610 nm, while BR Asp96---Asn is ineffective due to its slow photocycle. These experimental results suggest that aspartic acid 96 plays a crucial role for the reprotonation of the Schiff base. Both residues are essential for an effective proton pump.",
"The individual resonance Raman spectra of the PM568 and M412 forms of light-adapted purple membrane from Halobacterium halobium have been measured using the newly developed flow technique. For comparison purposes, the Raman spectra of the model chromophores, all-trans- and 13-cis retinal n-butylamine, both as protonated and unprotonated Schiff bases, have also been obtained. In agreement with previous work, the Raman data indicate that the retinal chromophore is linked to the purple membrane protein via a protonated. Schiff base in the case of the PM568 and an unprotonated Schiff base for the M412 form. The basic mechanism for color regulation in both forms appears to be electron delocalization. The spectral features of the two forms are different from each other and different from the model compound spectra."
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Endosonographic diagnosis of pancreatic body and tail carcinoma.
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Endosonography was performed in diagnosing and staging pancreatic body and tail carcinoma in two patients. In the first case endoscopy, abdominal ultrasound, and computed tomography were nondiagnostic in diagnosing the origin of submucosal gastric abnormalities. Endosonography diagnosed a pancreatic tail carcinoma with submucosal gastric involvement, and this was confirmed by endosonographic-guided cytology. Fundus varices due to segmented splenic vein involvement were found. Surgery was not recommended due to the advanced disease. In the second case pancreatic body carcinoma was diagnosed by ERCP and computed tomography. Transcutaneous ultrasonographic-guided cytological puncture confirmed the diagnosis. Endosonography revealed additional information of segmental portal hypertension with fundic varices due to splenic vein involvement. Autopsy confirmed the endosonographic diagnosis.
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"One of the goals of gastrointestinal endoscopy is to diagnose whether a lesion is malignant. The desire to improve the sensitivity of biopsy-sampling techniques prompted us to compare prospectively the reliability and accuracy of obtaining tissue by forceps biopsy, needle biopsy (21 gauge 13-mm long metal needles versus 18 gauge 20-mm long plastic needles), and salvage cytology in patients with endoscopically suspected malignancy. Samples were obtained in the order of needle biopsy (the order of metal and plastic needle biopsy was randomized), forceps biopsy, followed by salvage cytology. Needle biopsies were obtained by puncturing the lesion under direct vision while aspirating with a syringe. Twenty-three patients with gastrointestinal malignancy were studied (7 esophageal, 4 gastric, and 12 colonic). Forceps biopsies were positive in 18 of 23 (78%), missing 1 gastric and 4 colon malignancies. Metal needle biopsy was positive in 16 of 19 (84%), plastic needle biopsy in 17 of 22 (77%), and salvage cytology in 20 of 22 (91%). Accuracy was increased by a combination of techniques. Endoscopic needle biopsy is a simple and rapid method to evaluate lesions seen at endoscopy and is especially useful in evaluation of submucosal lesions.",
"Secondary neoplasms of the stomach are rare and are often clinical and diagnostic problems. Three patients with bleeding \"volcano-like\" ulcers were diagnosed by combined endoscopic \"salvage\" cytology and surgical biopsy as having metastatic submucosal lesions from hematologic spread. The combination of endoscopic appearance, clinical findings, and tissue and cytologic examination can lead to the correct diagnosis. The results from these cases support the utility of this cytologic technique in combination with biopsy in this clinical setting."
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Adenovirus type 5 as a vector for homologous recombination in CHO cells.
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The usefulness of adenovirus type 5 as a vector for homologous recombination was examined in CHO cells by using the adenine phosphoribosyltransferase (aprt) gene. Infection of a hemizygous CHO APRT- cell line containing a 3-bp deletion in exon 5 of the aprt gene with a recombinant adenovirus containing the wild-type gene resulted in restoration of the APRT+ phenotype at a frequency of 10(-5) to 10(-6) per infected cell. A relatively high frequency (approximately 6 to 20%) of the transductants appears to result from a homologous recombination event. The mutation on the chromosomal aprt gene is corrected in the homologous recombinants, and APRT expression is restored to a normal hemizygous level. Neither adenovirus nor exogenous promoter sequences are detected in the homologous recombinants. The remaining transductants result from random integration of the aprt gene with the adenovirus sequence. A number of adenovirus vectors containing different promoter sequences linked to the hamster aprt gene were constructed. A possible role for the promoter region in the homologous recombination event was indicated by the lack of homologous recombination in constructs lacking an active promoter.
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[
"The acquisition of high-level resistance to tubercidin (an adenosine analog) in CHO cells occurs in a single step at high frequency (10(-3) to 10(-4)) without mutagenesis. Analysis of a large number of independent mutants by a fluctuation test (Luria and Delbruk, 1943) indicates that they arise independently of the selection medium and all fall into the same complementation group. All mutants tested lack detectable adenosine kinase activity. An analysis of hybrids between mutant and wild-type cells indicates that resistance to tubercidin is a recessive marker which segregates as would be expected if it were a haploid locus in the parental CHO cell. Resistance to tubercidin is not linked to the X chromosome in CHO cells and appears to occur at much lower frequency in primary Chinese hamster cells and other cultured cell lines.",
"Somatic cell hybrids heterozygous at the emetine resistance locus (emtr/emt+) or the chromate resistance locus (chrr/chr+) are known to segregate the recessive drug resistance phenotype at high frequency. We have examined mechanisms of segregation in Chinese hamster cell hybrids heterozygous at these two loci, both of which map to the long arm of Chinese hamster chromosome 2. To follow the fate of chromosomal arms through the segregation process, our hybrids were also heterozygous at the mtx (methotrexate resistance) locus on the short arm of chromosome 2 and carried cytogenetically marked chromosomes with either a short-arm deletion (2p-) or a long-arm addition (2q+). Karyotype and phenotype analysis of emetine- or chromate-resistant segregants from such hybrids allowed us to distinguish four potential segregation mechanisms: (i) loss of the emt+- or chr+-bearing chromosome; (ii) mitotic recombination between the centromere and the emt or chr loci, giving rise to homozygous resistant segregants; (iii) inactivation of the emt+ or chr+ alleles; and (iv) loss of the emt+- or chr+-bearing chromosome with duplication of the homologous chromosome carrying the emtr or chrr allele. Of 48 independent segregants examined, only 9 (20%) arose by simple chromosome loss. Two segregants (4%) were consistent with a gene inactivation mechanism, but because of their rarity, other mechanisms such as mutation or submicroscopic deletion could not be excluded. Twenty-one segregants (44%) arose by either mitotic recombination or chromosome loss and duplication; the two mechanisms were not distinguishable in that experiment. Finally, in hybrids allowing these two mechanisms to be distinguished, 15 segregants (31%) arose by chromosome loss and duplication, and none arose by mitotic recombination.",
"We present evidence for a two-step model for expression of the recessive phenotype at the diploid adenine phosphoribosyl transferase (aprt) locus in Chinese hamster ovary cells. This model proposes a high-frequency event leading to allelic inactivation and a low-frequency event leading to a structural alteration of the APRT protein. Either event can occur first, resulting in two types of heterozygous cells. The proposed model is based on analysis of Chinese hamster ovary presumptive aprt heterozygotes and APRT- mutants, derived by two different laboratories. The major class of heterozygotes (class 1) had approximately 50% parental APRT activity, 50% immunologically precipitable APRT protein, and only wild-type enzyme as based on two-dimensional gel electrophoresis and thermal inactivation studies. We propose that one allele at the aprt locus has been inactivated in these heterozygotes. APRT- mutants derived from any single class 1 heterozygote arose at a low frequency and contained either no immunologically detectable APRT protein or an APRT enzyme which was, in most cases, demonstrably altered. The second class of heterozygotes, consisting of two independent isolates, gave rise to APRT- cells at a high frequency (10(-3) to 10(-5). These heterozygous cell lines had 50% of parental APRT activity and only wild-type spot, or wild-type and an electrophoretic variant spot, on two-dimensional gels. These aprt heterozygotes appear to have arisen by mutation at one allele. APRT- mutants derived from either heterozygote of this class had all lost the wild-type activity, consistent with the proposed model.",
"The role of DNA repair in mutagenesis was studied in normal, repair-proficient Chinese hamster ovary cells and in two mutant strains that are deficient in excision repair. By using the mutagen 7-bromomethylbenz[a]anthracene (7-BrMeBA) and the technique of alkaline elution of DNA, the mutants were found to be defective at or before the incision step of excision repair. Dose--responses were determined for cell killing, mutation induction at three loci, and sister chromatid exchanges over a survival range of 1.0--0.1 after 7-BrMeBA treatment. The mutants were 5-fold more sensitive to killing than were the normal cells, but the degree of hypersensitivity to mutation induction varied depending on the mutant strain, the genetic marker, and the dose of mutagen. In each instance, the dose--response curve for mutations was essentially linear in the repair-deficient cells. In the normal cells, however, the curves for induced resistance to thioguanine and azaadenine were complex and were curvilinear with increasing slope at low doses. This behavior may be attributable to saturation of the excision repair system. No difference was seen in the efficiency of inducing ouabain-resistant mutations in the repair-deficient cells compared to the normal cells, indicating a qualitatively different behavior of this marker. These results are consistent with excision repair of 7-BrMeBA damage being error-free in Chinese hamster ovary cells. Sister chromatid exchange, another manifestation of DNA damage, also was induced with greater efficiency in the repair-deficient cells.",
"We have developed a system that permits analysis of targeted homologous recombination at an endogenous, chromosomal gene locus in cultured mammalian cells. Using a hemizygous, adenine phosphoribosyltransferase (APRT)-deficient, Chinese hamster ovary (CHO) cell mutant as a transfection recipient, we have demonstrated correction of a nonrevertible deletion mutation by targeted homologous recombination. Transfection with a plasmid carrying a fragment of the APRT gene yielded APRT+ recombinants at a frequency of approximately 4.1 x 10(-7). The ratio of targeted recombination to nontargeted integrations of plasmid sequences was approximately 1:4000. Analysis of 31 independent APRT+ recombinants revealed conversions of the endogenous APRT gene, targeted integration at the APRT locus, and a third class of events in which the plasmid donor APRT fragment was converted to a full-length, functional gene.",
"It has been documented that the activity of a specific promoter can be occluded by the presence of another promoter element upstream. We present evidence for a phenomenon contradictory to that predicted by the promoter occlusion theory. Transcription from the hamster aprt (adenine phosphoribosyltransferase) promoter was augmented instead of repressed in transfected mouse L cells when an upstream Moloney murine sarcoma virus enhancer-promoter element was induced with butyrate. Without an adjacent Moloney murine sarcoma virus element, butyrate could not activate the aprt promoter."
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Isolation and characterization of Escherichia coli suppressor strains that reduce the copy number of a mutant ColE1 high-copy-number plasmid.
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We isolated three Escherichia coli suppressor strains that reduce the copy number of a mutant ColE1 high-copy-number plasmid. These mutations lower the copy number of the mutant plasmid in vivo up to 15-fold; the wild-type plasmid copy number is reduced by two- to threefold. The suppressor strains do not affect the copy numbers of non-ColE1-type plasmids tested, suggesting that their effects are specific for ColE1-type plasmids. Two of the suppressor strains show ColE1 allele-specific suppression; i.e., certain plasmid copy number mutations are suppressed more efficiently than others, suggesting specificity in the interaction between the suppressor gene product and plasmid replication component(s). All of the mutations were genetically mapped to the chromosomal polA gene, which encodes DNA polymerase I. The suppressor mutational changes were identified by DNA sequencing and found to alter single nucleotides in the region encoding the Klenow fragment of DNA polymerase I. Two mutations map in the DNA-binding cleft of the polymerase region and are suggested to affect specific interactions of the enzyme with the replication primer RNA encoded by the plasmid. The third suppressor alters a residue in the 3'-5' exonuclease domain of the enzyme. Implications for the interaction of DNA polymerase I with the ColE1 primer RNA are discussed.
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[
"A plasmid that consists of an 812-base-pair segment containing the replication origin of plasmid ColE1 and of a 1240-base-pair segment containing a beta-lactamase gene has been constructed. The plasmid DNA has three principal sites where transcription is initiated in vitro. One is located in the ColE1 segment 555 nucleotides upstream from the origin. Most transcription from this site extends past the origin; some of the transcripts form hybrids spontaneously with the template at their 3' portions. Cleavage of these transcripts by RNase H generates 3' termini at the origin region. When DNA polymerase I is included in the reaction along with RNA polymerase and RNase H, dAMP or dCMP is added directly onto the cleaved RNA molecules, most of which retain the intact 5' terminus. The addition of a deoxyribonucleotide to the cleaved RNA can be regarded as the first step of ColE1 DNA synthesis. Once it has served as a primer, the RNA is eliminated from the product by RNase H.",
"Escherichia coli RNA polymerase (EC 2.7.7.6), bound in a tight complex at an early T7 promoter, protects 41 to 43 base pairs of DNA from digestion by DNase. I. The protected DNA fragment contains both the binding site for RNA polymerase and the mRNA initiation point for the promoter. The sequence of the DNA fragment and the sequence of the mRNA that it codes for are presented here. A seven-base-pair sequence, apparently common to all promoters, is implicated in the formation of a tight binary complex with RNA polymerase.",
"The construction of a new wide-host-range, restriction-site bank, cosmid-cloning vehicle (pJRD215) is described. The wide-host-range properties and the ability to be transferred by conjugation, extend genetic engineering to those Gram-negative species that cannot be transformed. The vector permits the cloning of genes from Gram-negative bacteria using a complementation screening procedure in a mutant host. This procedure is simplified by the possibility of construction of a cosmid gene bank so that only a few hundred clones need to be screened. Subsequent subcloning of the gene of interest is facilitated by the presence of at least 23 unique cloning sites.",
"Replication of ColE1-type plasmids is known to be regulated by a plasmid-specific RNA (RNA I), whose binding to the transcript (RNA II) from the primer promoter results in inhibition of formation of the primer for DNA replication. In this paper, it is shown that binding of RNA I to the homologous RNA II is inhibited by an RNA I specified by a plasmid of different compatibility. The inhibition is caused by the reversible interaction of RNA II with the heterologous RNA I, which competes with reversible interaction of the two homologous RNAs at a step preceding their stable binding. As predicted from these results, the copy numbers of both ColE1 and RSF1030 are increased when both plasmids are present in the same cell. The Rom protein enhances the reversible interaction.",
"rho factor-mediated transcription termination at the tr1 terminator site of bacteriophage lambda is examined. Mutations affecting the termination event are characterised. These mutations define features of the site which seem to be important to terminator function. In addition, other related transcriptional and translational regulatory elements are defined within the region surrounding the termination site. The potential molecular interactions and structural overlaps of these control signals apparently couple the regulation of the decision between lytic and lysogenic growth patterns by phage lambda.",
"The restriction map of a BamHI DNA fragment that contains the recA gene of Escherichia coli has been established and a large portion of the fragment's nucleotide sequence has been determined. The coding region of the recA gene contains 1059 nucleotide residues and encodes a single protein of 353 amino acid residues. The amino acid sequence of the first five residues of the NH2 terminus of the recA protein agrees with the sequence predicted from the DNA sequence except for the absence of formylmethionine in the purified protein. Immediately after the coding sequence, there is a G+C-rich sequence with dyad symmetry followed by an A+T-rich sequence. These could signal termination of transcription. The site of initiation for synthesis in vitro of the recA messenger RNA has been determined by analysis of the 5' nucleotide sequence of [gamma-32P]ATP-labeled transcripts. The promoter region shos a high degree of symmetry and contains sequences commonly found in recognition and binding sites for RNA polymerase.",
"DNA polymerase I of Escherichia coli provides an excellent model for the study of template-directed enzymatic synthesis of DNA because it is a single subunit enzyme, it can be obtained in large quantities and the three-dimensional structure of the polymerizing domain (the Klenow fragment) has recently been determined (Ollis et al., 1985). One approach to assigning functions to particular portions of the structure is to correlate the altered enzymatic behavior of mutant forms of DNA polymerase I with the change in the primary sequence of the protein. Towards this end we have developed a rapid procedure for mapping any polA mutation to a region no larger than 300 base-pairs within the polA gene. Two series of polA deletion mutants with defined end-points were constructed in vitro and cloned into bacteriophage lambda. These phages can then be used to map precisely E. coli polA mutants. Twelve polA- alleles have been mapped in this way and for nine of them the nature of the mutational change has been determined by DNA sequence analysis. Two of the mutations, polA5 and polA6, which affect the enzyme-DNA interaction, provide evidence for the location of the DNA binding region on the polymerase three-dimensional structure."
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Polymorphisms in the human T-cell receptor Vb6 family
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The human T-cell receptor (Tcr) Vb6 family has been scrutinized for polymorphisms, both in coding as well as in intronic sequences by polymerase chain reaction (PCR), subsequent multiple electroblot hybridizations, and sequence analysis. Multiplex PCR is an efficient means of screening for Tcr variability. Four novel loci could be distinguished and several new alleles are described including two pseudogenes. The Vb6 family is characterized by an intronic stretch of simple repetitive (gt)n sequences. These elements are hypervariable, especially in the Vb6.7 subfamily, where they are particularly long. The unexpected persistence of simple repetitive sequences in Tcr and major histocompatibility complex (MHC) class II genes over extended periods of the vertebrate evolutionary history can be interpreted in parallel terms in both gene families.
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[
"A new method for determining nucleotide sequences in DNA is described. It is similar to the \"plus and minus\" method [Sanger, F. & Coulson, A. R. (1975) J. Mol. Biol. 94, 441-448] but makes use of the 2',3'-dideoxy and arabinonucleoside analogues of the normal deoxynucleoside triphosphates, which act as specific chain-terminating inhibitors of DNA polymerase. The technique has been applied to the DNA of bacteriophage varphiX174 and is more rapid and more accurate than either the plus or the minus method.",
"To compare and contrast the human T cell antigen receptor (TcR) alpha and beta chain messages found in human thymocytes to those previously isolated from human peripheral blood T lymphocytes and other nonthymic sources, 13 TcR alpha and 13 TcR beta cDNA were isolated from a human thymocyte library and the nucleotide sequences were determined. The data indicate that, as was found in the peripheral T lymphocytes, the majority of the TcR alpha and TcR beta chain thymocyte cDNA were derived from potentially functional messages. Although the thymocyte-derived TcR cDNA do not contain any unique structural features when compared to TcR cDNA from mature T lymphocytes, 4 new J alpha segments, 17 new V-gene segments (9 V alpha; 8 V beta) and 7 additional V-gene families (4 V alpha and 3 V beta) and sequences had been identified. The exon C beta O, found in many murine thymocyte TcR beta messages, was not found in over 75 human beta chain messages. Based on these new data, a revised estimate of human TcR V alpha, J alpha and V beta repertoires is calculated. The most significant change has been the increase in the estimated number of human TcR V beta-gene segments to a total of about 100 distributed among about 18 families. The V alpha families are now revised upward to 16, with a total number of V alpha segments of 50. The estimate of the J alpha segments in humans remains between 50-100.",
"Polymorphisms of human TCR gene products have been suggested by the description of a mAb, OT145, that identifies a subset of TCRs in some individuals but not in others (6). Here we demonstrate that this mAb detects a TCR allotype of the V beta 6.7 gene. Two allelic products of this V gene differ by two nonconservative amino acid substitutions. The mAb OT145 appears to react with V beta 6.7 a gene products (\"+\" allele), but not with V beta 6.7b gene products (\"-\" allele). This represents the first direct demonstration that TCR V gene allotypes exist and provides a possible explanation for immune responses under the control of TCR V genes and for disease associations with TCR V genes.",
"A direct quantitative and phenotypic cytofluorographic analysis of TCR-gamma/delta+ lymphocytes as well as an immunohistologic study of their tissue distribution and microanatomy was made possible by the availability of two mAbs (anti-TCR-delta 1 and anti-C gamma M1) specific for framework determinants on human TCR gamma and delta chains, respectively. TCR-gamma/delta+ lymphocytes, ranging between greater than 0.5 and 16% of CD3+ cells, were found in fetal and postnatal thymus, fetal and adult peripheral lymphoid organs, and adult peripheral blood. While TCR-gamma/delta+ lymphocytes comprised a small subpopulation of T cells (mean, approximately 4%) occasionally greater than 10-16% of CD3+ cells expressed TCR-gamma/delta. Virtually all TCR-gamma/delta+ thymocytes/lymphocytes expressed CD7, CD2, and CD5 but were heterogeneous with respect to their expression of CD1, CD4, CD8, CD28, CD11b, CD16, and Leu-7. Human TCR-gamma/delta+ cells populate both organized lymphoid tissues (thymus, tonsil, lymphnode, and spleen) as well as the gut- and skin-associated lymphoid systems at similar frequencies without obvious tropism for epithelial microenvironments. TCR-gamma/delta+ lymphocytes tend to be located within a given organ wherever TCR-alpha/beta+ lymphocytes are found. This study shows that TCR-gamma/delta+ lymphocytes constitute a small but numerically important, phenotypically diverse T cell population distributed throughout the body. These results support the concept that TCR-gamma/delta+ cells comprise a distinct, functionally heterogeneous, mature T cell sublineage that may substantially broaden the T cell repertoire at all immunologically relevant sites.",
"Variable processing of heteronuclear RNA into multiple, defined species of messenger RNA is a well-established phenomenon in a number of systems, including myelin basic protein, calcitonin, troponin T4 and immunoglobulins. Within a single B cell, immunoglobulin heavy-chain peptides often exist as two related but distinct species, a membrane-bound form and a secreted form, both of which originate from the same germline constant(C)-region gene via alternative RNA processing pathways. Furthermore, at certain stages of B-cell development, a single variable(V)-region element can be concurrently expressed in immunoglobulins of both the IgM and IgD isotypes, presumably resulting from the alternative splicing of one variable-region exon to different constant-region genes. We report here the existence of an alternative RNA splicing pathway available to murine T-cell receptor (TCR) beta-chain transcripts. Sequence analysis of beta-chain complementary DNA clones reveals a C beta 1 species containing a 72-base pair (bp) insertion between the joining (J beta) and C beta elements. This sequence is inserted via an alternative splicing pathway available to C beta 1 transcripts. The optional exon is located between the J beta 1 cluster and the first exon of C beta 1. Interestingly, this element can be spliced to C beta 2 in the New Zealand White mouse, in which the C beta 1 gene is deleted. Use of the alternative splicing pathway varies between 1% and 18% of total C beta clones, depending on the source of isolation.",
"The human TCR beta-chain gene complex includes at least 57 variable (V) gene segments, a number estimated using a combination of Southern blots of conventional and pulsed field gels, sequence analysis of cDNA clones, and from the analysis of genomic cosmid and phage clones. This number includes six TCR beta-chain V genes in four new families identified here by sequence analysis of clones derived from a human TCR beta-chain specific cDNA library. Comparison of the sequences of the new V beta genes with previously reported V beta sequences reveals predicted similarities but less than 75% nucleic acid identity that establishes them as new V beta families. One of the new V beta gene families includes three genes and the other three are single member families. Identification of these six new V beta genes falling into four V beta families brings the total number of transcribed human V beta families to 24 and makes it possible to refine the estimate of the total number of human TCR V beta genes to 57."
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V-J recombination in mice with partially methylated transgene arrays.
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We have previously described a line of transgenic mice with multiple head-to-tail copies of an artificial V-J recombination substrate and have shown that the methylation of this transgene is under the control of a dominant strain-specific modifier gene, Ssm-1. When the transgene array is highly methylated, no recombination is detectable, but when it is unmethylated, V-J joining is seen in the spleen, bone marrow, lymph nodes, and Peyer's patches but not in the thymus or nonlymphoid tissues, including brain tissue. Strikingly, in mice with partially methylated transgene arrays, rearrangement preferentially occurs in hypomethylated copies. Therefore, V-J recombination is negatively correlated with methylated DNA sequences. In addition, it appears that recombination occurs randomly between any two recombination signal sequences within the transgene array. This lack of target preference in an unselectable array of identical targets rules out simple mechanisms of one-dimensional tracking of a V(D)J recombinase complex.
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[
"Both C kappa regions in MPC 11 cells are rearranged into active transcripion units, one producing a normal kappa chain and the other an internally deleted kappa fragment lacking a V region. The gene coding for the kappa fragment mRNA is aberrantly rearranged and lacks a site for V leads to C kappa splicing. An alternative splicing event which deletes the V region from the nuclear RNA precursor generates the kappa fragment mRNA.",
"We have produced transgenic mice which synthesize chimeric mouse-rabbit immunoglobulin (Ig) kappa light chains following in vivo recombination of an injected unrearranged kappa gene. The exogenous gene construct contained a mouse germ-line kappa variable (V kappa) gene segment, the mouse germ-line joining (J kappa) locus including the enhancer, and the rabbit b9 constant (C kappa) region. A high level of V-J recombination of the kappa transgene was observed in spleen of the transgenic mice. Surprisingly, a particularly high degree of variability in the exact site of recombination and the presence of non germ-line encoded nucleotides (N-regions) were found at the V-J junction of the rearranged kappa transgene. Furthermore, unlike endogenous kappa genes, rearrangement of the exogenous gene occurred in T-cells of the transgenic mice. These results show that additional sequences, other than the heptamer-nonamer signal sequences and the promoter and enhancer elements, are required to obtain stage- and lineage- specific regulation of Ig kappa light chain gene rearrangement in vivo.",
"To determine whether a foreign unrearranged immunoglobulin gene can be functionally rearranged and expressed in vivo, a rabbit b9 kappa light chain gene construct containing a single germ-line kappa chain variable (V) region gene (V kappa), the five kappa chain joining (J) segments (J kappa), and the kappa chain constant (C) region germ-line gene (C kappa) was introduced into fertilized mouse eggs. Eleven transgenic mice carrying 1-30 copies of the rabbit kappa gene construct were obtained. Rearrangement of the transgene due to V kappa-J kappa recombination was observed in the spleen of all the mice lines analyzed. Only the J kappa 1 and J kappa 2 segments, which have canonical sequences for rearrangement and high-level expression, are utilized in assembly of the rabbit gene. V kappa-J kappa 1 and V kappa-J kappa 2 joining was also observed in the thymus but not in nonlymphoid tissue. Polyadenylylated rabbit kappa chain transcripts of 1.2 kilobases were found in the spleen of the transgenic mice. The level of transcription was low despite a high level of rearrangement. Three transgenic mice lines secreted kappa light chains encoded by the foreign rabbit gene. Serum rabbit kappa chains were associated with mouse mu and gamma 1 heavy chains. However, hybrid antibody molecules containing both rabbit and mouse kappa light chains were also found in the serum of these animals. These results suggest that, although the rabbit kappa chain gene construct contains the necessary sequences for gene assembly, sequences implicated in stage- and tissue-specific regulation of kappa chain gene rearrangement are either missing or not recognized by mouse lymphoid cells.",
"In cells of the B-lymphocyte lineage, 8.4 kb transcripts are constitutively produced from unrearranged kappa constant region (kappa 0) loci. To help elucidate the molecular basis of this phenomenon, we have determined the nucleotide sequence surrounding the site of transcriptional initiation. The kappa 0 transcripts are initiated within a unique Eco RI fragment located about 8 kb upstream from the C kappa gene. The start site is about 36 nucleotides downstream from a Hogness consensus sequence (TGTAAAT) and nearly 200 nucleotides upstream from a sequence that is similar to those encoding the signal peptides of kappa light chains. These features, which are usually found in the 5' flanking regions of kappa variable region genes, suggest that the kappa 0 initiation sequence may be an evolutionary relic of some common ancestral 5' element. In contrast, there is no discernible V kappa-encoding element in 780 nucleotides of sequence downstream from the initiation site. From pulse-chase-labeling experiments with a pre-B-cell hybridoma line and direct measurements of transcriptional activity in isolated nuclei, we have estimated that the rate of transcription of the kappa 0 locus is significantly lower than that of a rearranged V kappa-C kappa gene. This result, together with the fact that unrearranged V kappa genes are transcriptionally silent, suggests that structural features of both the V kappa and C kappa loci contribute to the overall transcriptional efficiency of a rearranged V kappa-C kappa gene. The 8.4 kb transcripts are not processed into any stable RNA products, despite the fact that they contain some apparently normal splice junctions; rather, they are degraded within the nucleus at about half the rate with which a kappa mRNA precursor is processed. Conceivably, the transcriptional activity of the kappa 0 locus might be a prerequisite for its recombinatorial activity.",
"The rabbit kappa light chain gene family is characterized by the presence of two constant region (C kappa) genes; the C kappa 1 gene encodes the constant region of the principal rabbit immunoglobulin light chain, the C kappa 2 gene being not or very poorly expressed in domestic rabbits. There exist four major K1 alleles (b4, b5, b6, and b9), which are unequally expressed in heterozygous rabbits at the K1 locus. Here, we compare the nucleotide sequences of the joining (J) clusters of the kappa light chain gene (J kappa) linked to the b4K2 locus and to the b4 and b9 alleles at the K1 locus. As for C kappa genes, there is evidence for intergenic conversion between the J kappa 1 and J kappa 2 clusters as well as maximum divergence in the expressed J segments. The b9 J kappa 1 cluster differs from its b4 counterpart in that two out of the five J kappa segments (J1 and J2) are expressed instead of only one. This implies that preferential expression of the b4 allele as compared to the b9 allele is not only correlated to the number of available J kappa pieces. The b9 J2 segment is functional in spite of the presence of a termination codon immediately upstream of its coding region. Two major structural differences were observed between the J-C intron sequences of the b9 and b4 alleles; namely a 160-base-pair deletion of an A + T-rich sequence in b9 (which also occurs in the K2 locus) and a 10-base-pair deletion plus some substitutions in the region corresponding to the mouse kappa intron activating element. These differences could underlie the lower transcriptional rate of the b9 allele.",
"We have recently proposed that a common recombinase performs all of the many variable region gene assembly events in B and T cells, and that the specificity of these joining events is mediated by regulating the \"accessibility\" of the involved gene segments. To test this possibility, we have introduced \"accessible\" T cell receptor (TCR) variable region gene segments into a pre-B cell line capable of recombining endogenous and transfected immunoglobulin (Ig) variable region gene segments. Although the corresponding \"inaccessible\" endogenous TCR gene segments do not rearrange in this line or in B cells in general, the introduced TCR gene segments join very frequently and, in fact, closely resemble introduced Ig gene segments in their recombination characteristics. These observations suggest a new role for conventional Ig transcriptional enhancers--recombinational enhancement. Our studies provide insight into additional aspects of the joining mechanism such as N region insertion, aberrant joining, and recombination-recognition sequence requirements for joining.",
"A simple and rapid method for transferring RNA from agarose gels to nitrocellulose paper for blot hybridization has been developed. Poly(A)+ and ribosomal RNAs transfer efficiently to nitrocellulose paper in high salt (3 M NaCl/0.3 M trisodium citrate) after denaturation with glyoxal and 50% (vol/vol) dimethyl sulfoxide. RNA also binds to nitrocellulose after treatment with methylmercuric hydroxide. The method is sensitive: about 50 pg of specific mRNA per band is readily detectable after hybridization with high specific activity probes (10(8) cpm/microgram). The RNA is stably bound to the nitrocellulose paper by this procedure, allowing removal of the hybridized probes and rehybridization of the RNA blots without loss of sensitivity. The use of nitrocellulose paper for the analysis of RNA by blot hybridization has several advantages over the use of activated paper (diazobenzyloxymethyl-paper). The method is simple, inexpensive, reproducible, and sensitive. In addition, denaturation of DNA with glyoxal and dimethyl sulfoxide promotes transfer and retention of small DNAs (100 nucleotides and larger) to nitrocellulose paper. A related method is also described for dotting RNA and DNA directly onto nitrocellulose paper treated with a high concentration of salt; under these conditions denatured DNA of less than 200 nucleotides is retained and hybridizes efficiently."
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Interactions between c-Myb and DNA
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The DNA-binding domain of c-Myb consists of three homologous tandem repeats of 52 amino acids. The structure of the third (C-terminal) repeat obtained by NMR analysis has a conformation related to the helix-turn-helix motif. To identify the role of each repeat in the sequence recognition of DNA, we analyzed specific interactions between c-Myb and DNA by measuring binding affinities for systematic mutants of Myb-binding DNA sites and various truncated c-Myb mutants. We found that specific interactions are localized unevenly in the AACTGAC region in the consensus binding site of c-Myb: The first adenine, third cytosine, and fifth guanine are involved in very specific interactions, in which any base substitutions reduce the binding affinity by > 500-fold. On the other hand, the interaction at the second adenine is less specific, with the affinity reduction in the range of 6- to 15-fold. The seventh cytosine involves a rather peculiar interaction, in which only guanine substitution abolishes the specific binding. The binding analyses, together with the chemical protection analyses, showed that the c-Myb fragment containing the second and third repeats covers the AACTGAC region from the major groove of DNA in such an orientation that the third repeat covers the core AAC sequence. These results suggest that the third repeat recognizes the core AAC sequence very specifically, whereas the second repeat recognizes the GAC sequence in a more redundant manner. The first (N-terminal) repeat, which covers the major groove of DNA only partially, is not significant in the sequence recognition, but it contributes to increase the stability of the Myb-DNA complex. The presence of an N-terminal acidic region upstream of the first repeat, which is important for the activation of c-myb protooncogene, was found to reduce the binding affinity by interfering with the first repeat in binding to DNA.
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[
"Results of systematic base-substitution experiments suggest that the lambda repressor dimer, made of identical subunits, recognizes the \"pseudo(2-fold)symmetric\" operator sequence asymmetrically. Base substitutions within the consensus half of the operator affect binding more than base substitutions within the nonconsensus half of the operator. Furthermore, changing the nonconsensus base pairs to the consensus base pairs does not increase, but decreases, binding. Evidently, the two subunits of the lambda repressor dimer bind to the two halves of the operator differently. This is consistent with the recently determined crystal structure of the complex, which shows that the relative positioning of the amino acids to the DNA bases are slightly different in the two halves of the operator. The sequence-specific interactions indicated by the systematic base-substitution experiments correlate well with the locations of the specific contacts found in the complex. Thus, the amino acids of lambda repressor, mainly of alpha 3-helix and the N-terminus arm, seem to directly read-out the DNA sequence by forming specific hydrogen bonds and hydrophobic contacts to the DNA bases. The observed asymmetric recognition suggests that no recognition code governs amino acids and DNA bases in protein-DNA interactions.",
"The mechanism of action of cro protein was probed by measuring its ability to protect DNA against methylation by dimethyl sulfate and its effect on transcription in vitro. The cro protein binds to the same three sites in the right operator (OR) of bacteriophage lambda DNA as does the lambda repressor. Dimethyl sulfate protection experiments reveal major groove contacts for both proteins, and cro protein protects from methylation a subset of those purines protected by lambda repressor. These experiments also show that the relative affinity of these two proteins for the three operator sites is different: whereas lambda repressor binds with an affinity OR1 greater than OR2 greater than OR3, the order for cro protein is OR3 greater than (OR1, OR2). As predicted by these results, cro protein, like the lambda repressor, blocks in vitro transcription of cI and cro from the two divergent promoters that overlap OR. Also as predicted, transcription of cI is turned off at lower cro protein concentrations than is transcription of cro, whereas the opposite order of repression is obtained with lambda repressor. These results describe the molecular mechanism of cro protein action and show that two regulatory proteins can bind to the same three adjacent sites in DNA with markedly different consequences.",
"We measured quantitatively the binding affinities of purified Cro repressor to the chemically synthesized wild-type and mutant OR1 operators, consisting of all three possible base-pair substitutions and of thymine to uracil substitutions at each base-pair position of the 17-base-pair operator sequence. The sequence-specific interactions between Cro repressor and the operator DNA occur at the symmetrically disposed outer 7-base-pair positions of each half operator and at the central base-pair position. The binding of Cro is almost symmetrical with respect to the pseudo-twofold symmetry of the binding site. The binding free energy changes calculated from the affinity changes are mostly additive for specific Cro binding. Also the binding affinities of Cro to the operators or any other DNA sequences can be predicted by simple addition of free energy changes of single base substitutions. We isolated cro mutants by site-directed mutagenesis and studied their DNA binding to the wild-type and base-substituted mutant operators. The sequence-specific contacts derived from such studies are significantly different from the models proposed by Ohlendorf et al. [Ohlendorf, D. H., Anderson, W. F., Takeda, Y. & Matthews, B. W. (1982) Nature (London) 298, 719-723] and by Hochschild et al. [Hochschild, A., Douhan, J., III, & Ptashne, M. (1986) Cell 47, 807-816]."
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Myosin-I is associated with Golgi-derived vesicles in intestinal crypts
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In the intestinal brush border, the mechanoenzyme myosin-I links the microvillus core actin filaments with the plasma membrane. Previous immunolocalization shows that myosin-I is associated with vesicles in mature enterocytes (Drenckhahn, D., and R. Dermietzel. 1988. J. Cell Biol. 107:1037-1048) suggesting a potential role mediating vesicle motility. We now report that myosin-I is associated with Golgi-derived vesicles isolated from cells that are rapidly assembling brush borders in intestinal crypts. Crypt cells were isolated in hyperosmotic buffer, homogenized, and fractionated using differential- and equilibrium-density centrifugation. Fractions containing 50-100-nm vesicles, a similar size to those observed in situ, were identified by EM and were shown to contain myosin-I as demonstrated by immunoblotting and immunolabel negative staining. Galactosyltransferase, a marker enzyme for trans-Golgi membranes was present in these fractions, as was alkaline phosphatase, which is an apical membrane targeted enzyme. Galactosyltransferase was also present in vesicles immuno-purified with antibodies to myosin-I. Villin, a marker for potential contamination from fragmented microvilli, was absent. Myosin-I was found to reside on the vesicle "outer" or cytoplasmic surface for it was accessible to exogenous proteases and intact vesicles could be immunolabeled with myosin-I antibodies in solution. The bound myosin-I could be extracted from the vesicles using NaCl, KI and Na2CO3, suggesting that it is a vesicle peripheral membrane protein. These vesicles were shown to bundle actin filaments in an ATP-dependent manner. These results are consistent with a role for myosin-I as an apically targeted motor for vesicle translocation in epithelial cells.
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[
"A rapid and simple method for the isolation of membranes from subcellular organelles is described. The procedure consists of diluting the organelles in ice-cold 100 mM Na2CO3 followed by centrifugation to pellet the membranes. Closed vesicles are converted to open membrane sheets, and content proteins and peripheral membrane proteins are released in soluble form. Here we document the method by applying it to various subfractions of a rat liver microsomal fraction, prepared by continuous density gradient centrifugation according to Beaufay et al. (1974, J. Cell Biol. 61:213-231). The results confirm and extend those of previous investigators on the distribution of enzymes and proteins among the membranes of the smooth and rough endoplasmic reticulum. In the accompanying paper (1982, J. Cell Biol. 93:103-110) the procedure is applied to peroxisomes and mitochondria.",
"After the initiation of bud formation, cells of the yeast Saccharomyces cerevisiae direct new growth to the developing bud. We show here that this vectorial growth is facilitated by activity of the MYO2 gene. The wild-type MYO2 gene encodes an essential form of myosin composed of an NH2-terminal domain typical of the globular, actin-binding domain of other myosins. This NH2-terminal domain is linked by what appears to be a short alpha-helical domain to a novel COOH-terminal region. At the restrictive temperature the myo2-66 mutation does not impair DNA, RNA, or protein biosynthetic activity, but produces unbudded, enlarged cells. This phenotype suggests a defect in localization of cell growth. Measurements of cell size demonstrated that the continued development of initiated buds, as well as bud initiation itself, is inhibited. Bulk secretion continues in mutant cells, although secretory vesicles accumulate. The MYO2 myosin thus may function as the molecular motor to transport secretory vesicles along actin cables to the site of bud development.",
"Rat liver polysomal RNA was translated in the rabbit reticulocyte lysate and in the wheat germ cell-free protein-synthesizing systems, using [(35)S]methionine as label. The catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase, EC 1.11.1.6) that was synthesized was isolated by immunoprecipitation and characterized by electrophoresis in sodium dodecyl sulfate/polyacrylamide gels followed by fluorography. The catalase made in both systems migrated more slowly during electrophoresis than did purified peroxisomal catalase. By comparison with standards of known molecular mass, the cell-free products were estimated to be about 4000 daltons larger than the purified enzyme. We also investigated the biosynthesis of catalase in vivo by injecting [(35)S]methionine into rats. The precursor of catalase known to be synthesized in liver and found in the high-speed supernatant 8 min later [Lazarow, P. B. & de Duve, C. (1973) J. Cell Biol. 59, 491-506] was isolated immunochemically. For comparison, 1-day-old completed catalase was immunoprecipitated from peroxisomes. The migrations in sodium dodecyl sulfate gels of the 8-min-old precursor and the subunit of the day-old enzyme were indistinguishable and approximately the same as the migration of the cell-free products. These results indicate that catalase's apparent size does not change when it enters peroxisomes but rather decreases during the chemical purification procedure."
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Identification of a 65-kD glycoprotein of Trypanosoma (Duttonella) vivax.
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A 65-kD glycoprotein (gp65) of Trypanosoma (Duttonella) vivax was identified using a murine monoclonal antibody (mAb 4E1) that had been raised against formalin-fixed, in vitro-propagated, uncoated forms. Intracellular localization studies utilizing the mAb in immunofluorescence on fixed, permeabilized T. vivax bloodstream forms and immunoelectron microscopy on thin sections of Lowicryl K4M-embedded cells revealed labeling of vesicles and tubules in the posterior portion of the parasite. Some mAb-labeled vesicles contained endocytosed 10 nm BSA-gold after incubation of the parasites with the marker for 5-30 min at 37 degrees C, and the greatest degree of colocalization was observed after 5 min. Double labeling experiments using the mAb and a polyclonal anti-variant surface glycoprotein (VSG) antibody to simultaneously localize both gp65 and VSG demonstrated that there was little overlap in the distribution of these antigens. Thus, gp65 is associated with tubules and vesicles that are involved in endocytosis but which appear to be distinct from VSG processing pathways within the cell. Using the mAb for immunoblot analyses, gp65 was shown to be enriched in a fraction of solubilized membrane proteins eluted from either immobilized Con A or Ricinus communis agglutinin and was found to possess carbohydrate linkages cleaved by both endoglycosidase H and O-glycosidase, suggesting the presence of N- and O-linked glycans. Protease protection and crosslinking experiments suggest that gp65 is a transmembrane protein with trypsin cleavage and NH2-crosslinking sites on the lumenal face of the vesicles.
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[
"The genome of Trypanosoma brucei carries over a hundred genes coding for different variants of the major surface glycoprotein. Activation of some of these genes is accompanied by a duplication and transposition of the gene (the basic copy) to another region in the genome where it is transcribed. We present here physical maps of the basic and transposition-activated genes for two surface glycoproteins of Trypanosoma brucei, stock 427. In both cases the transposed segment starts 1-2 kb in front of the coding region and ends within the 3'-terminal region of the gene. The DNA segments flanking both transposed genes are indistinguishable and share a 6-kb stretch upstream and a 8-kb stretch downstream of the transposed segment not cut by several restriction endonucleases. The 5' borders of the two transposed segments are homologous and contain sequences present in many copies in the genome. A different repeated sequence has previously been found at the 3' edge of the transposed segment. The replicative transposition may, therefore, involve a unidirectional gene conversion initiated by base pairing between the edges of the transposed sequence and a single expression site elsewhere in the genome.",
"We have characterized a cDNA encoding a cysteine-rich, acidic integral membrane protein (CRAM) of the parasitic protozoa Trypanosoma brucei and Trypanosoma equiperdum. Unlike other membrane proteins of T. brucei, which are distributed throughout the cell surface, CRAM is concentrated in the flagellar pocket, an invagination of the cell surface of the trypanosome where endocytosis has been documented. Accordingly, CRAM also locates to vesicles located underneath the pocket, providing evidence of its internalization. CRAM has a predicted molecular mass of 130 kilodaltons and has a signal peptide, a transmembrane domain, and a 41-amino-acid cytoplasmic extension. A characteristic feature of CRAM is a large extracellular domain with a roughly 66-fold acidic, cysteine-rich 12-amino-acid repeat. CRAM is conserved among different protozoan species, including Trypanosoma cruzi, and CRAM has structural similarities with eucaryotic cell surface receptors. The most striking homology of CRAM is to the human low-density-lipoprotein receptor. We propose that CRAM functions as a cell surface receptor of different trypanosome species.",
"Two Trypanosoma vivax stocks from East Africa have been adapted to rats and mice. Adaptation was induced by rapid passage at two- to four-day intervals in sublethally irradiated rats. After 200 such passages, the two stocks gave rise to parasitemias of 10(9)-10(10) trypanosomes/ml in peripheral blood, and the infection was fatal in 90% of the rats. By passaging the rat-adapted T. vivax into normal mice at two- to three-day intervals for over 200 passages, the two stocks also became pathogenic to mice. One of the stocks was also capable of maintenance in non-irradiated rats. The two stocks displayed a marked degree of pleomorphism in irradiated and non-irradiated rats and mice. In the early rising parasitemia, the organisms were predominantly short, with a well formed undulating membrane, a pointed posterior end, and a large terminal kinetoplast. As parasitemia approached its peak, the organisms transformed into long, slender forms with an inconspicuous undulating membrane, an elongated posterior end, and a sub-terminal kinetoplast. The short forms associated with the early, rising parasitemia were more infective for mice than the long forms encountered at peak parasitemia. Although the two rodent-adapted stocks retained their pathogenicity for goats, neither the original stocks nor their corresponding rodent-adapted stocks could be cyclically transmitted by tsetse flies. The availability of these stocks will greatly facilitate investigations on East African T. vivax which would otherwise be difficult to carry out in experimental rodents.",
"The nucleotide sequence of a partial cDNA for the bovine low-density lipoprotein (LDL) receptor revealed an open reading frame of 264 amino acids that encodes the COOH-terminal 25% of the receptor protein. The sequence predicts a cytoplasmic domain of 50 amino acids at the COOH terminus, followed in order by a membrane-spanning region of 27 hydrophobic amino acids and an externally disposed stretch of 42 amino acids, that is rich in serine and threonine residues and appears to be the site of O-linked glycosylation. This orientation was confirmed by proteolysis experiments in which the relevant fragments were localized by blotting with anti-peptide antibodies and a galactose-specific lectin. The extracytoplasmic domain of the LDL receptor contains a region that is 38% identical with a 96 amino acid sequence in the precursor to mouse epidermal growth factor (EGF), a peptide hormone. This unexpected homology raises the possibility that proteins involved in growth stimulation (e.g., EGF precursor) and nutrient delivery (e.g., LDL receptor) may have a common evolutionary origin.",
"A cDNA cloned from Trypanosoma brucei brucei codes for a putative membrane protein which is homologous to the erythrocyte glucose transporter and several other sugar transporters from Escherichia coli, yeast, algae and Leishmania. This cDNA hybridizes to a 2.3-kb mRNA that accumulates to a much higher degree in the bloodstream mammalian form than in the procyclic insect form of the parasite. The correlation between the expression of this gene and the hexose metabolism of Leishmania enriettii and T. brucei suggest that these 2 related genes probably encode hexose transporters. The gene encoding this mRNA is a member of a multigene family. The putative hexose transporter gene is highly conserved among Kinetoplastidae, indicating an important role for this protein in the parasite life cycle.",
"Fractionation of MOPC 41 DL-1 tumors revealed that the mRNA for the light chain of immunoglobulin is localized exclusively in membrane-bound ribosomes. It was shown that the translation product of isolated light chain mRNA in a heterologous protein-synthesizing system in vitro is larger than the authentic secreted light chain; this confirms similar results from several laboratories. The synthesis in vitro of a precursor protein of the light chain is not an artifact of translation in a heterologous system, because it was shown that detached polysomes, isolated from detergent-treated rough microsomes, not only contain nascent light chains which have already been proteolytically processed in vivo but also contain unprocessed nascent light chains. In vitro completion of these nascent light chains thus resulted in the synthesis of some chains having the same mol wt as the authentic secreted light chains, because of completion of in vivo proteolytically processed chains and of other chains which, due to the completion of unprocessed chains, have the same mol wt as the precursor of the light chain. In contrast, completion of the nascent light chains contained in rough microsomes resulted in the synthesis of only processed light chains. Taken together, these results indicate that the processing activity is present in isolated rough microsomes, that it is localized in the membrane moiety of rough microsomes, and, therefore, that it was most likely solubilized during detergent treatment used for the isolation of detached polysomes. Furthermore, these results established that processing in vivo takes place before completion of the nascent chain. The data also indicate that in vitro processing of nascent chains by rough microsomes is dependent on ribosome binding to the membrane. If the latter process is interfered with by aurintricarboxylic acid, rough microsomes also synthesize some unprocessed chains. The data presented in this paper have been interpreted in the light of a recently proposed hypothesis. This hypothesis, referred to as the signal hypothesis, is described in greater detail in the Discussion section.",
"African trypanosomes resist the immune response of their mammalian hosts by varying the surface glycoprotein which constitutes their antigenic identity. The molecular mechanism of this antigenic variation involves the successive activation of a series of genes which code for different variant surface glycoproteins (VSGs). We have studied the expression of two VSG genes (those of VSG-1 and VSG-28) in Trypanosoma equiperdum, and we report the following findings. (i) The expression of both VSG genes is associated with the duplication and transposition of corresponding basic copy genes. (ii) The duplicated transposed copy appears to be the expressed copy. (iii) Although there are multiple genes which cross-hybridize with the VSG-1 cDNA probe, only one of these appears to be used as a template for the expression-linked copy in four independent BoTat-1 clones. (iv) Analysis of the genomic environments of the expressed VSG-1 genes from each of four independently derived BoTat-1 trypanosome clones revealed that there are at least three different sites into which the expression-linked copy can be inserted."
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Enterobacter aerogenes strains resistant to imipenem and extended-spectrum cephalosporin
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Enterobacter aerogenes strains resistant to imipenem were isolated in 10 patients, 7 of whom had received imipenem-cilastatin. The strains were differentiated by biotype, antibiotype, and plasmid content. All of the strains overproduced a chromosomal cephalosporinase and lost a major outer membrane protein with a size of about 40 kDa. In 5 of the 10 patients, E. aerogenes strains resistant to extended-spectrum cephalosporin were isolated during the same stay. In three patients, the similarity between the imipenem-susceptible and -resistant strains suggests the occurrence of mutation and reversion in vivo. The combination imipenem-cilastatin has been critically important for use with multiresistant strains of Enterobacter spp., but its use increases the risk of selection of imipenem-resistant strains.
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[
"Carbapenem resistance was studied in a clinical isolate of Enterobacter cloacae, strain 201 (MIC of imipenem and meropenem, 16 micrograms/ml). This strain was analyzed comparatively with the carbapenem-susceptible parent strain 200, an equally susceptible revertant, 201-Rev, and in vitro-selected mutants with different levels of carbapenem resistance. All strains produced similarly high amounts of the same cephalosporinase (pIapp = 8.8). Strain 201 apparently lacked two major outer membrane proteins of ca. 37 and 38 kDa, while 201-Rev produced only the 37-kDa protein. The permeability coefficient, determined with cephaloridine, was reduced up to ninefold in the resistant strains which also showed a substantial reduction in the uptake of [14C]meropenem. The introduction of the plasmid-borne ampD gene (whose product decreases the expression of ampC) resulted in almost complete cessation of cephalosporinase production in all strains and a substantial decrease in the MICs of the carbapenems which remained, however, 8- to 16-fold higher than those determined for the susceptible strains containing the ampD gene. This \"residual\" resistance was attributed to reduced outer membrane permeability. The contribution of cephalosporinase production was verified in a reverse experiment, in which the introduction of ampC into a low-level cephalosporinase producer resulted in a fourfold increase in the carbapenem MICs. From these results, we infer that reduced outer membrane permeability and high-level cephalosporinase production can operate in conjunction in clinical isolates of E. cloacae to confer imipenem resistance.",
"A spontaneous one-step mutant of Salmonella paratyphi A selected on ampicillin showed cross-resistance to all beta-lactam antibiotics except imipenem and to aminoglycosides, chloramphenicol, tetracycline, trimethoprim, and quinolones. It also grew as small colonies. Examination of the cell envelope of the mutant showed a quantitative decrease in three major outer membrane proteins of 40.6, 39.6 (presumably porins), and 24 kilodaltons and quantitative as well as qualitative modifications in the ladder pattern of lipopolysaccharide. Direct evidence for decreased permeability in the mutant included reduced uptake of [3H]glucose and norfloxacin, reduced accessibility of aztreonam and benzylpenicillin to penicillin-binding proteins in whole cells, and decreased diffusion of lactose and cephaloridine into proteoliposomes that were reconstituted with outer membrane proteins from the mutant. There was also loss of invasiveness of the mutant into HeLa cells. We assume that a pleiotropic mutation was responsible for multiple alterations in the outer membrane components of the resistant mutant of S. paratyphi A.",
"Carbapenems such as imipenem and meropenem are not rapidly hydrolyzed by commonly occurring beta-lactamases. Nevertheless, it was possible, by mutagenesis and selection, to isolate mutant strains of Enterobacter cloacae and Proteus rettgeri that are highly resistant to meropenem and imipenem. Two alterations were noted in the E. cloacae mutants. First, the mutant strains appeared to be strongly derepressed in the production of beta-lactamases, which reached a very high level when the strains were grown in the presence of imipenem. Second, these mutants were deficient in the production of nonspecific porins, as judged by the pattern of outer membrane proteins as well as by reconstitution assays of permeability. As with most porin-deficient mutants, their cultures were unstable, and their cultivation in the absence of carbapenems rapidly led to an overgrowth of porin-producing revertants. Analysis of the data suggests that the synergism between the lowered outer membrane permeability and the slow but significant hydrolysis of carbapenems by the overproduced enzymes can explain the resistance phenotypes quantitatively, although the possibility of alteration of the target cannot be excluded at present. With P. rettgeri mutants, there was no indication of further derepression of beta-lactamase, but the enzyme hydrolyzed imipenem much more efficiently than the E. cloacae enzyme did. In addition, the major porin was absent in one mutant strain. These results suggest that a major factor for the carbapenem resistance of these enteric bacteria is the porin deficiency, and this conclusion forms a contrast to the situation in Pseudomonas aeruginosa, in which the most prevalent class of imipenem-resistant mutants appears to lack the specific channel protein D2 yet retains the major nonspecific porin F.",
"Treatment of a partially purified preparation of cell walls of Escherichia coli with Triton X-100 at 23 C resulted in a solubilization of 15 to 25% of the protein. Examination of the Triton-insoluble material by electron microscopy indicated that the characteristic morphology of the cell wall was not affected by the Triton extraction. Contaminating fragments of the cytoplasmic membrane were removed by Triton X-100, including the fragments of the cytoplasmic membrane which were normally observed attached to the cell wall. Treatment of a partially purified cytoplasmic membrane fraction with Triton X-100 resulted in the solubilization of 60 to 80% of the protein of this fraction. Comparison of the Triton-soluble and Triton-insoluble proteins from the cell wall and cytoplasmic membrane fractions by polyacrylamide gel electrophoresis after removal of the Triton by gel filtration in acidified dimethyl formamide indicated that the detergent specifically solubilized proteins of the cytoplasmic membrane. The proteins solubilized from the cell wall fraction were qualitatively identical to those solubilized from the cytoplasmic membrane fraction, but were present in different proportions, suggesting that the fragments of cytoplasmic membrane which are attached to the cell wall are different in composition from the remainder of the cytoplasmic membrane of the cell. Treatment of unfractionated envelope preparations with Triton X-100 resulted in the solubilization of 40% of the protein, and only proteins of the cytoplasmic membrane were solubilized. Extraction with Triton thus provides a rapid and specific means of separating the proteins of the cell wall and cytoplasmic membrane of E. coli.",
"Reexamination of Serratia marcescens isolates obtained in 1982 revealed two organisms that were resistant to the penem FCE 22101 (MIC, 512 micrograms/ml) and imipenem (MIC, 16 micrograms/ml) and that had slightly reduced susceptibilities to meropenem (MIC, 0.12 micrograms/ml). MICs of these agents for typical S. marcescens isolates were 1 to 8, 0.25 to 0.5, and 0.03 micrograms/ml, respectively. The two isolates were fully susceptible to broad-spectrum cephalosporins, and only one was highly resistant to ampicillin and carbenicillin (MICs, greater than 1,024 micrograms/ml). Both isolates had beta-lactamases that focused at pIs 8.2 and 9.7. The penicillin-resistant isolate additionally produced the TEM-1 enzyme. The enzymes with pIs of 8.2 and 9.7 were separated by cation-exchange chromatography. The pI 8.2 beta-lactamase was a class I enzyme of the type found in most S. marcescens isolates. It was almost inactive against carbapenems and penems, as was the class I enzyme from another S. marcescens strain. The pI 9.7 enzyme hydrolyzed penems and carbapenems rapidly: kcat (turnover number) values for FCE 22101, imipenem, and meropenem were 3.4, 26, and 1% of the kcat value for cephaloridine, respectively; kcat/Km values were 140, 915, and 150% of the kcat/Km value for cephaloridine, respectively. Otherwise, the pI 9.7 enzyme had predominantly penicillinase activity. It was inhibited more readily by clavulanate than by tazobactam and was inactivated by the chelating agents EDTA and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. Expression of the pI 9.7 enzyme was not associated with any plasmid, and production was not transferred to Escherichia coli K-12 recipients, even after the mobilizing plasmid pUZ8 was inserted into the S. marcecens donor strains.",
"The outer membrane of imipenem-resistant mutants of Pseudomonas aeruginosa with decreased permeability to imipenem was shown by Western (immuno-) blotting to contain protein D1 and to lack protein D2. Protein D2 was purified and was shown to allow the permeation of imipenem at a rate higher than expected from its molecular weight. Spontaneous imipenem-resistant mutants of P. aeruginosa PAO1 appeared at a frequency of 10(-8) in the laboratory and did not synthesize protein D2. Experiments performed with intact cells carrying plasmid pHN4 containing the gene for L-1 beta-lactamase from Pseudomonas maltophilia showed that this channel could also be used by SM-7338, Sch 33755, and Sch 33440 but apparently not by Sch 34343 or Sch 29482.",
"We isolated an imipenem-resistant strain, GN17203, of Pseudomonas aeruginosa. The strain produced a beta-lactamase that hydrolyzed imipenem. The beta-lactamase was encoded by a 31-MDa plasmid, pMS350, which belongs to incompatibility group P-9. The plasmic conferred resistance to beta-lactams, gentamicin, and sulfonamide and was transferable by conjugation to P. aeruginosa but not to Escherichia coli. The molecular weight of the purified enzyme was estimated to be 28,000, and the isoelectric point was 9.0. The enzyme showed a broad substrate profile, hydrolyzing imipenem, oxyiminocephalosporins, 7-methoxycephalosporins, and penicillins. The enzyme activity was inhibited by EDTA, iodine, p-chloromercuribenzoate, CuSO4, and HgCl2 but not by clavulanic acid or sulbactam."
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Induction of the interleukin 1 beta gene by lipopolysaccharide-phorbol myristate acetate-dibutyryl cyclic AMP
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Transfection of U937 and THP-1 cells with a recombinant plasmid, pIL1(4.0kb)-CAT, containing 4 kb of the interleukin 1 beta (IL-1 beta) gene upstream regulatory sequence resulted in inducer-dependent expression of chloramphenicol acetyltransferase activity. Treatment of the transfected cells with various combinations of the inducers lipopolysaccharide, phorbol myristate acetate, and dibutyryl cyclic AMP upregulated the IL-1 beta promoter. In U937 and THP-1 cells, maximum stimulation of both the endogenous IL-1 beta gene and pIL1(4.0kb)-CAT transfectants was observed following treatment with the combination of inducing agents lipopolysaccharide-phorbol myristate acetate-dibutyryl cyclic AMP. This combination of inducing agents was used to identify and study, at the molecular level, some of the regulatory elements necessary for induction of the IL-1 beta gene. A series of 5' deletion derivatives of the upstream regulatory sequence were used in transient transfection assays to identify an 80-bp fragment located between -2720 and -2800 bp upstream of the mRNA start site that was required for induction. Exonuclease III mapping, electrophoretic mobility shift assays (EMSA), and DNA sequence analysis of this region were used to identify a transcription factor binding sequence which contained a potential cyclic AMP response element (CRE/ATF)- and NF-kappa B-like binding site. Site-directed mutagenesis of the CRE/ATF-like site resulted in the loss of binding of a specific factor or factors as determined by EMSA. The loss of binding activity directly correlated with a loss of approximately 75% of promoter activity as determined in transient transfection assays. As determined by EMSA, the factor binding to the CRE/ATF-like site was present in nuclear extracts prepared from both uninduced and induced THP-1 and U937 cells. However, the intensity of the band appeared to be increased when nuclear extracts from induced cells were used. In contrast to the CRE/ATF mutation, which resulted in the loss of promoter activity, mutation of the NF-kappa B-like site resulted in a moderate increase in activity in U937 cells. A similar increase in promoter activity was not observed in THP-1 cells. From these studies, we conclude that a CRE/ATF-like site and a factor or factors interacting with this site are essential for the maximum induction of the IL-1 beta gene in stimulated U937 and THP-1 cells.
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[
"Hormonal regulatory elements within the phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) (PEPCK) promoter region were mapped using a series of 5' deletions linked to the amino-3'-glycosyl phosphotransferase structural gene. These deletion mutants were stably transfected into the genome of FTO-2B hepatoma cells. A 47-base pair region of the PEPCK promoter was identified which was essential for stimulation by dibutyryl cAMP. A 12-base pair core sequence (CTTACGTCAGAG) within this region shows significant homology with sequences in four other cAMP-regulated genes. There are two glucocorticoid regulatory elements within the promoter, as well as an inhibitory element which depresses the level of basal gene transcription. The deletion of this inhibitory sequence prevents the induction of the chimeric gene by dexamethasone. The existence of the hormone regulatory domains within the PEPCK promoter was confirmed by attaching these elements upstream of the heterologous Herpes simplex virus thymidine kinase structural gene, containing its own promoter.",
"cAMP regulates transcription of the gene encoding the alpha-subunit of human chorionic gonadotropin (hCG) in choriocarcinoma cells (BeWo). To define the sequences required for regulation by cAMP, we inserted fragments from the 5' flanking region of the alpha-subunit gene into a test vector containing the simian virus 40 early promoter (devoid of its enhancer) linked to the bacterial chloramphenicol acetyltransferase (CAT) gene. Results from transient expression assays in BeWo cells indicated that a 1500-base-pair (bp) fragment conferred cAMP responsiveness on the CAT gene regardless of position or orientation of the insert relative to the viral promoter. A subfragment extending from position -169 to position -100 had the same effect on cAMP-induced expression. Furthermore, the entire stimulatory effect could be achieved with an 18-bp synthetic oligodeoxynucleotide corresponding to a direct repeat between positions -146 and -111. In the absence of cAMP, the alpha-subunit 5' flanking sequence also enhanced transcription from the simian virus 40 early promoter. We localized this enhancer activity to the same -169/-100 fragment containing the cAMP response element. The 18-bp element alone, however, had no effect on basal expression. Thus, this short DNA sequence serves as a cAMP response element and also functions independently of other promoter-regulatory elements located in the 5' flanking sequence of the alpha-subunit gene.",
"We constructed a series of recombinant genomes which directed expression of the enzyme chloramphenicol acetyltransferase (CAT) in mammalian cells. The prototype recombinant in this series, pSV2-cat, consisted of the beta-lactamase gene and origin of replication from pBR322 coupled to a simian virus 40 (SV40) early transcription region into which CAT coding sequences were inserted. Readily measured levels of CAT accumulated within 48 h after the introduction of pSV2-cat DNA into African green monkey kidney CV-1 cells. Because endogenous CAT activity is not present in CV-1 or other mammalian cells, and because rapid, sensitive assays for CAT activity are available, these recombinants provided a uniquely convenient system for monitoring the expression of foreign DNAs in tissue culture cells. To demonstrate the usefulness of this system, we constructed derivatives of pSV2-cat from which part or all of the SV40 promoter region was removed. Deletion of one copy of the 72-base-pair repeat sequence in the SV40 promoter caused no significant decrease in CAT synthesis in monkey kidney CV-1 cells; however, an additional deletion of 50 base pairs from the second copy of the repeats reduced CAT synthesis to 11% of its level in the wild type. We also constructed a recombinant, pSV0-cat, in which the entire SV40 promoter region was removed and a unique HindIII site was substituted for the insertion of other promoter sequences.",
"Previous studies have suggested that murine interleukin 1 (IL 1) may be synthesized as a high m.w. precursor. Using specific antibodies against murine IL 1, we have analyzed the primary form of IL 1 synthesized by normal peritoneal macrophages and P388D1 cell line macrophages, and in vitro using poly (A)+ RNA from stimulated normal and cell line macrophages. In all cases, the labeled protein immunoprecipitated with the anti-IL 1 antibodies exhibited a m.w. of 33,000 on SDS gels. This 33,000 m.w. protein was not an aggregate of low m.w. IL 1. Addition of excess purified low m.w. IL 1 completely blocked the immunoprecipitation of the 33,000 m.w. protein. When cells were pulsed with [35S]methionine for 1 to 5 hr and then incubated in medium containing unlabeled methionine for 19 hr, labeled low m.w. IL 1 was detected in the culture fluid. If cells were pulsed with [35S]methionine to label the 33,000 m.w. protein and then incubated in the presence of a maximally effective concentration of the protein synthesis inhibitor, cycloheximide, the low m.w. IL 1 was still found in the culture fluid. Our results indicate that IL 1 is synthesized as a 33,000 m.w. precursor that is converted to the low m.w. form that is found in the culture fluid of stimulated murine macrophages.",
"In these studies, we have identified DNA sequences and specific protein interactions necessary for transcriptional regulation of the human prointerleukin 1 beta (proIL-1 beta) gene. A cell-type-independent lipopolysaccharide (LPS)-responsive enhancer element located between -3757 and -2729 bp upstream from the transcription start site (cap site) consisted of at least six discrete subregions which were essential to the maximal induction by LPS in transfected monocytes. The enhancer also appeared to mediate phorbol myristate acetate induction in monocytes and IL-1 responsiveness in fibroblasts. Deletion and base substitution mutations along with DNA binding studies demonstrated that the enhancer contained a minimum of three functional protein binding sequences, two of which appeared to be important for gene induction. One of the essential proteins which bound to the enhancer was similar or identical to members of the C/EBP family of transcription factors required for both IL-1- and LPS-specific induction of the IL-6 gene (i.e., the NF-IL6 proteins). When ligated to the proIL-1 beta cap site-proximal region (located between -131 to +12), both the proIL-1 beta and the simian virus 40 enhancer elements functioned more efficiently in monocytes than in HeLa cells, which are not normally competent for IL-1 beta expression. When ligated to the murine c-fos promoter, however, the proIL-1 beta enhancer was inducible in phorbol myristate acetate-stimulated HeLa cells, suggesting the existence of a proIL-1 beta promoter-proximal requirement for tissue specificity.",
"Transcription of the gene for cytosolic Phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) (PEPCK) from rat liver is increased by cAMP and glucocorticoids and decreased by insulin. A PEPCK-thymidine kinase (TK) chimeric gene was transfected into FTO-2B rat hepatoma cells, which were TK-deficient. Previous studies showed that a cAMP regulatory element is located at the 5' end of the PEPCK gene. In this report, we demonstrate that the 5' end of the gene also contains a glucocorticoid regulatory element, but not one for insulin. Regions of the PEPCK gene that contain these regulatory elements were attached to the Herpes simplex virus TK structural gene containing its own promoter. The hormone regulatory elements within the 5' flanking region of the PEPCK gene conferred cAMP and glucocorticoid responsiveness on the TK gene after transfection into FTO-2B cells. Like viral enhancer elements, these regulatory elements functioned properly when placed in either orientation at various positions 5' or 3' to TK. The presence of the SV40 enhancer element upstream from the PEPCK-TK gene had little effect on the basal level of expression or hormonal regulation of the chimeric gene.",
"The long terminal repeat of Moloney Murine Sarcoma Virus (MoMSV) contains an imperfect direct repeat that serves as a strong transcriptional enhancer. The strength of the MoMSV enhancer is strongly dependent on the presence of glucocorticoid hormone. Mapping studies in combination with DNAase I footprinting experiments define the presence of glucocorticoid regulatory elements at the promoter-proximal ends of each enhancer repeat. These elements behave like inducible enhancers: their regulatory activity is independent of position and orientation when they are linked in cis to a heterologous promoter. These data demonstrate the modular nature of the MoMSV enhancer and identify the glucocorticoid receptor as one of the trans-acting factors that interact with the MoMSV enhancer and mediate its transcriptional activity."
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Defective helper RNAs for packaging Sindbis virus RNA replicons
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Since the recovery of infectious RNA transcripts from full-length cDNA clones, alphavirus genome RNAs have been engineered to allow expression of heterologous RNAs and proteins. The highest levels of expression of heterologous products are achieved when the viral structural genes are replaced by the heterologous coding sequences. Such recombinant RNAs are self-replicating (replicons) and can be introduced into cells as naked RNA, but they require trans complementation to be packaged and released from cells as infectious virion particles. In this report, we describe a series of defective Sindbis virus helper RNAs which can be used for packaging Sindbis virus RNA replicons. The defective helper RNAs contain the cis-acting sequences required for replication as well as the subgenomic RNA promoter which drives expression of the structural protein genes. In cells cotransfected with both the replicon and defective helper RNAs, viral nonstructural proteins translated from the replicon RNA allow replication and transcription of the defective helper RNA to produce the virion structural proteins. A series of defective helper RNAs were compared for the ability to package the replicon RNA as well as for the ability to be replicated and packaged. One defective helper RNA not only packaged the replicon but also was itself encapsidated and would be useful under conditions in which extensive amplification is advantageous. Other defective helper RNAs were able to package the replicon efficiently but were packaged very poorly themselves. These helpers should be useful for applications in which expression of the viral structural proteins or virus spread is not desired.
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[
"Defective-interfering (DI) particles are helper-dependent deletion mutants which interfere specifically with the replication of the homologous standard virus. Serial passaging of alphaviruses in cultured cells leads to the accumulation of DI particles whose genomic RNAs are heterogeneous in size and sequence composition. In an effort to examine the sequence organization of an individual DI RNA species generated from Sindbis virus, we isolated and sequenced a representative cDNA clone derived from a Sindbis DI RNA population. Our data showed that: (i) the 3' end of the DI RNA template was identical to the 50 nucleotides at the 3' end of the standard RNA; (ii) the majority (75%) of the DI RNA template was derived from the 1,200 5'-terminal nucleotides of the standard RNA and included repeats of these sequences; and (iii) the 5' end of the DI RNA template was not derived from the standard RNA, but is nearly identical to a cellular tRNAAsp (S. S. Monroe and S. Schlesinger, Proc. Natl. Acad. Sci. U.S.A. 80:3279-3283, 1983). We have also utilized restriction fragments from cloned DNAs to probe by blot hybridization for the presence of conserved sequences in several independently derived DI RNA populations. These studies indicated that: (i) a 51-nucleotide conserved sequence located close to the 5' end of several alphavirus RNAs was most likely retained in the DI RNAs; (ii) the junction region containing the 5' end of the subgenomic 26S mRNA was deleted from the DI RNAs; and (iii) the presence of tRNAAsp sequences was a common occurrence in Sindbis virus DI RNAs derived by passaging in chicken embryo fibroblasts.",
"We constructed cDNA libraries from poly(A)+ RNA isolated from cell lines of two different inbred strains of mice, and screened the libraries with a cDNA clone encoding a human transplantation antigen. Three cDNA clones were identified, sequenced and found to encode amino acid sequences highly homologous to portions of a known mouse transplantation antigen. Comparison of the cDNA sequences of mouse transplantation antigens with the constant region domains of the mouse immunoglobulin mu gene reveals a striking homology, which suggests that the two genes share a common ancestor. Antibody genes undergo DNA rearrangement during B cell differentiation that are correlated with their expression. In contrast, DNA blots with these cDNA probes suggest that the genes for the transplantation antigens are not rearranged in the genomes of liver or embryo cells, which express these antigens, as compared with sperm cells, which do not express these antigens. In Bam Hl-digested liver DNAs from different inbred strains of mice, 10-15 bands of hybridization were found. Accordingly, the genes encoding the transplantation antigens appear to constitute a multigene family with similar gene numbers in different mice."
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The cyclic AMP response element of the rat glucagon gene mediates transcriptional responses to 8-bromo-cAMP and protein kinase A.
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The cyclic AMP (cAMP) response element (CRE) of the rat glucagon gene (Glu-CRE, 5'-TGACGTCA-3') mediates transcriptional responses to 8-bromo-cAMP and protein kinase A (PKA) in a glucagon-producing hamster islet cell line (InR1G9). By several different DNA-protein binding assays, we show that the transcription factor CREB binds to the CRE octamer and that additional nuclear proteins bind to sequences adjacent to the CRE. Mutation of the Glu-CRE octamer attenuates both the binding of CREB and cAMP-dependent PKA-stimulated transcriptional activity in transient transfection experiments but does not affect the binding of adjacent CREB-associated proteins. Progressive deletions and clustered point mutations of the sequences flanking the Glu-CRE identify sequences (5'-TCATT-3') located both 5' and 3' to the core CRE octamer that bind several proteins. Two proteins with molecular masses of 80 and 100 kDa bind to each of the 5' and 3' TCATT sites. Formation of additional protein-DNA complexes containing 45- and 20-kDa proteins depends upon the integrity of both TCATT sequences. Deletion or point mutation of the TCATT motif located on the 3' side of the CRE octamer results in enhanced transcriptional responses to PKA, suggesting that the CREB-associated proteins decrease the ability of CREB to mediate PKA-stimulated transcription. Results from these studies demonstrate that nucleotides flanking the core CRE octamer can influence the activity of the CRE by serving as binding sites for proteins that modulate the function of CREB and suggest a mechanism to explain why some consensus palindromic CREs are less responsive to cAMP stimulation than others.
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[
"Using in vivo dimethylsulfate footprinting, we have analyzed protein-DNA interactions within two regions upstream of the tyrosine aminotransferase (TAT) gene that are characterized by an altered chromatin structure in TAT-expressing as compared to nonexpressing cells. All the identified protein contacts to DNA are found exclusively in the TAT-expressing hepatoma cells. In vitro analyses of specific DNA-binding factors in crude nuclear extracts yield DNAase I footprints that correlate well with the binding sites in vivo. Surprisingly, all DNA-binding activities are present in nuclei of TAT-expressing and nonexpressing cells, indicating that the mere presence of factors is not sufficient for their interaction with a binding site in vivo. Genomic sequencing reveals methylation of CpG dinucleotides in the regions analyzed in nonexpressing cells, whereas no methylation is found in TAT-expressing cells. In vitro methylation at a cytosine residue within a footprint region prevents the interaction of a factor with its binding site.",
"Two glucocorticoid response elements (GREs) located 2.5 kb upstream of the transcription initiation site of the tyrosine aminotransferase gene were identified by gene transfer experiments and shown to bind to purified glucocorticoid receptor. Although the proximal GRE has no inherent capacity by itself to stimulate transcription, when present in conjunction with the distal GRE, this element synergistically enhances glucocorticoid induction of gene expression. Cooperativity of the two GREs is maintained when they are transposed upstream of a heterologous promoter. An oligonucleotide of 22 bp representing the distal GRE is sufficient to confer glucocorticoid inducibility. As evidenced by the mapping of DNAase I hypersensitive sites, local alterations in the structure of chromatin at the GREs take place as a consequence of hormonal treatment.",
"We show here that the alpha-fetoprotein gene (AFP) promoter can be regulated by AP-1 activity using transient transfection assays. AFP promoter activity induced by c-jun/c-fos can be repressed by cotransfected glucocorticoid receptor. The DNA sequence conferring AP-1 activity was located in the proximal promoter region. Gel retardation assays using the AFP proximal promoter identified an AP-1-like sequence which can bind to bacterially expressed c-jun protein. This AP-1-like element, when cloned into the tk promoter, responds to the AP-1 activity of c-jun/c-fos products in both CV-1 and F-9 cells. The element overlaps with a consensus glucocorticoid-responsive element which was shown to confer negative modulation of AFP promoter activity. A 23-base pair DNA element containing the overlapping glucocorticoid-responsive element and AP-1 sites can be positively regulated by glucocorticoid receptor in the absence of c-jun/c-fos products. When plasmids expressing glucocorticoid receptor, c-jun and c-fos are cotransfected together, they repress each other. Thus, these data demonstrate that negative regulation of the AFP gene by glucocorticoid may be due to the interference of AP-1 activity by glucocorticoid receptor either by direct competition for DNA binding or via protein-protein interaction. They provide another example of transcriptional regulation of developing-associated genes between two major signal transduction pathways in response to extracellular stimuli. This supports the model that expression of alpha-fetoprotein is regulated during development by the effect on transcription of antagonism between glucocorticoid receptor and fos/jun.",
"The glucagon gene is expressed specifically in the alpha cells of the pancreatic islets. We show here that 300 base pairs of the 5'-flanking region of the rat glucagon gene, linked to a chloramphenicol acetyltransferase reporter plasmid transfected into islet cell lines of different hormone-producing phenotypes, directs transcription only in glucagon-producing islet cells. Deletional and linker-scanning mutations and DNase I footprinting assays identify three transcriptional control elements within these 300 base pairs. Two of these elements (G2 and G3) independently display enhancerlike functions on both homologous and heterologous promoters in glucagon (alpha) cells, but only on heterologous promoters in insulin- (beta) and somatostatin- (delta) expressing cells, and not in non-islet cells. The proximal promoter element (G1), characterized by low intrinsic transcriptional activity, is critical for specific expression of the glucagon gene in alpha cells. However, nuclear extracts prepared from all three islet cell phenotypes give similar protection to the three control elements of the glucagon 5'-flanking sequence. We conclude that these phenotypically distinct islet cell lines all contain regulatory DNA-binding proteins interacting with the three control elements of the glucagon gene, but that factors interacting with the glucagon promoter result in transcriptional activation only in alpha cells, to restrict glucagon gene expression to these cells. These observations suggest that interactions of nuclear proteins with cis-control elements are involved in the programmed developmental expression of the islet polypeptide hormone genes.",
"Whereas molecular cloning experiments have provided evidence for the presence of two closely related genes for the catalytic subunit of the cAMP-dependent protein kinase, the possible interchangeability of these isoforms in initiating biological processes has not been examined. To test the role of the two forms of the kinase in regulating transcription, expression vectors containing the coding sequence of either kinase have been cotransfected with a fusion gene containing the prolactin promoter coupled to an appropriate marker gene. The results demonstrate that expression vectors for both isoforms of the catalytic subunit are able to increase prolactin promotor activity in a dose-dependent manner. The effects can be observed by measuring either marker gene activity or RNA levels. Transfection of an expression vector encoding an inactive catalytic subunit did not stimulate prolactin promoter activity. The results provide additional evidence for the role of the catalytic subunit of the cAMP-dependent kinase in mediating regulation of specific gene transcription and demonstrate that both forms of the catalytic subunit are capable of participating in the regulation of transcription.",
"A gene, encoding a liver-enriched transcriptional activator protein (LAP) has been isolated. LAP is a 32-kD protein that stimulates the transcription of chimeric genes containing albumin D-promoter elements both in vivo and in vitro. LAP shares extensive sequence homology (71%) in its DNA-binding and leucine zipper domains with C/EBP. As a consequence, these two proteins show an indistinguishable DNA-binding specificity and readily heterodimerize. In addition, both genes, lap and cebp, are devoid of intervening sequences. Although correctly initiated transcripts from the LAP gene accumulate in the six examined tissues--liver, lung, spleen, kidney, brain, and testis--LAP protein is highly enriched in liver nuclei. Thus, the preferential accumulation of LAP protein in liver appears to be regulated post-transcriptionally.",
"Several cis-acting elements interact through their cognate trans-acting factors to confer placenta-specific expression to the alpha subunit gene of glycoprotein hormones. These elements include two tandemly arranged cAMP response elements (CREs, located between base pairs (bp) -146 and -111 relative to the transcription start site), an upstream regulatory element (URE, located between -180 and -150), and a CCAAT box (located between bp -100 and -80). Here, we identify a new regulatory region, junctional regulatory element (JRE), with critical nucleotides located between the CREs and CCAAT box (bp -120 to -100). Although the binding site of the JRE abuts the 3' CRE, methylation interference assays indicate that no overlap occurs between the contact points of the proteins that bind to the JRE and CRE. This new regulatory element is highly conserved across species and contains a palindromic binding site for a 50-kDa nuclear factor(s) which is distinct from the factors that bind the URE, CRE, and CCAAT box of the alpha subunit gene. Finally, gene transfer studies suggest that, although JRE binding activity is found in several cell types, this element acts relatively cell-specifically. We conclude that this element and its cognate trans-acting factor act in conjunction with the complexes formed over the URE, CREs, and CCAAT box to enhance the placenta-specific activity of the alpha subunit promoter."
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Transcriptional block preventing synthesis of bulk vegetative protein in Yersinia pestis KIM
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It is established that the medically significant yersiniae require the presence of physiological levels of Ca2+ (ca. 2.5 mM) for sustained growth at 37 degrees C and that this nutritional requirement is mediated by a shared ca. 70-kb Lcr plasmid. The latter also encodes virulence factors (Yersinia outer membrane proteins [Yops] and V antigen) known to be selectively synthesized in vitro at 37 degrees C in Ca(2+)-deficient medium. In this study, cells of Yersinia pestis KIM were first starved for Ca2+ at 37 degrees C to prevent synthesis of bulk vegetative protein and then, after cell division had ceased, pulsed with [35S]methionine. After sufficient chase to ensure plasminogen activator-mediated degradation of Yops, the remaining major radioactive peptides were separated by conventional chromatographic methods and identified as Lcr plasmid-encoded V antigen and LcrH (and possibly LcrG), ca. 10-kb Pst plasmid-encoded pesticin and plasminogen activator, ca. 100-kb Tox plasmid-encoded fraction 1 (capsular) antigen and murine exotoxin, and chromosomally encoded antigen 4 (pH 6 antigen) and antigen 5 (a novel hemin-rich peptide possessing modest catalase activity but not superoxide dismutase activity). Also produced at high concentration was a chromosome-encoded GroEL-like chaperone protein. Accordingly, the transcriptional block preventing synthesis of bulk vegetative protein at 37 degrees C in Ca(2+)-deficient medium may not apply to genes encoding virulence factors or to highly conserved GroEL (known in other species to utilize a secondary stress-induced sigma factor).
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[
"Yersinia enterocolitica isolates harboring a particular species of plasmid deoxyribonucleic acid showed a high degree of lethality for gerbils and caused the detachment of HEp-2 tissue cell monolayers. Strains cured of their plasmid deoxyribonucleic acid showed loss of these properties. However, invasiveness of HEp-2 cells was shown not to be a plasmid-mediated property. The expression of plasmid-associated properties, including at least three major outer membrane polypeptides, occurred during growth at 37 but not at 25 degrees C and was related to the concentration of calcium in the growth medium. The plasmid species associated with these properties ranged in molecular mass from 40 x 10(6) to 48 x 10(6) daltons and comprised a family of related plasmids.",
"Yersinia enterocolitica is now the species of Yersinia most frequently isolated from human and animal infections. The species includes pathogens and ubiquitous strains. Among the human pathogens, those isolated in America are more virulent than those isolated elsewhere, especially in Europe and Japan, and these isolates differ biochemically and serologically. The relation between Y. enterocolitica and Y. pestis only became obvious in 1980 with the discovery that at 37 degrees C Y. enterocolitica requires Ca++, a phenotype described in the 1960s for Y. pestis. This requirement as well as virulence is dependent on a 70-kilobase plasmid found later in Y. pseudotuberculosis and Y. pestis. Thus, many bacteriologists elected Y. enterocolitica as a model for bacterial invasiveness. However, studies with non-American strains were impeded by the lack of an inexpensive, simple animal test, a difficulty now circumvented by supplying an appropriate siderophore to the bacteria. Ca++ dependence can be viewed as a transition between free growth and protection against the immune system. In the latter phase, Y. enterocolitica synthesizes and releases large amounts of six plasmid-encoded outer membrane proteins. Most of these are under the control of the plasmid region governing Ca++ dependence. Mutants in this region either lose the Ca++ requirement at 37 degrees C or become unable to grow at 37 degrees C irrespective of the Ca++ concentration. The complex events leading to Ca++ dependence is still not understood. Virulence in Y. enterocolitica also depends on chromosomal genes: the endocytosis in intestinal epithelial cells seems not to be encoded by the pYV plasmid. Studies of Y. pseudotuberculosis suggest that this property depends on a single chromosomal locus, the study of which might be particularly important in the understanding of the first step in infection.",
"Virulent cells of Yersinia pestis, Yersinia pseudotuberculosis, and Yersinia enterocolitica are known to exhibit a low-calcium response in vitro characterized by restriction of growth and induction of V antigen at 37 degrees C in Ca2+-deficient media (Lcr+). A shared Lcr plasmid mediates these properties and encodes yersiniae outer membrane peptides (Yops) that are expressed in Lcr+ Y. pseudotuberculosis and Y. enterocolitica but not Y. pestis. We present direct evidence here verifying that synthesis of major Yops in the former two species is, like V, repressed by Ca2+ and that these structures are located primarily in the outer membrane. We also verified that rabbits infected with live Lcr+ Y. pestis can raise antibodies against V and Yops. Similar antisera, however, were recovered after immunization with sterile extracts of Ca2+-starved Lcr+ cells of Y. pestis. Results of immunoblots obtained with these antisera showed that restricted Y. pestis produced Yops of about 46 kDa (YopB) and 44 kDa (YopC) after shiftup by addition of Ca2+ at 37 degrees C or reduction of temperature to 26 degrees C. It is established that virulent cells of Y. pestis also possess a unique plasmid known to mediate pesticinogeny (Pst+). Restricted Lcr+, Pst- Y. pestis expressed YopB and YopC plus additional 76 kDa (YopF), 48 kDa (YopH), 36 kDa (YopD), 32.5 kDa (YopJ), and 27 kDa (YopE) outer membrane structures at concentrations comparable to those in Ca2+-starved Y. pseudotuberculosis and Y. enterocolitica. These findings indicate that carriage of the Pst plasmid prevents expression of the Lcr plasmid-mediated Yops in wild type Y. pestis.",
"Bichowsky-Slomnicki, Leah (The Weizmann Institute of Science, Rehovoth, Israel) and Shlomo Ben-Efraim. Biological activities in extracts of Pasteurella pestis and their relation to the \"pH 6 antigen.\" J. Bacteriol. 86:101-111. 1963.-Three kinds of biological activities could be found in crude extracts prepared from all the tested strains of Pasteurella pestis: cytotoxicity for monocytes, ability to agglutinate red blood cells, and induction of primary inflammatory reactions of the skin. All these biological activities were related to the presence of the \"pH 6 antigen.\" In addition, fractions of the pH 6 antigen devoid of agglutinating activity against red blood cells, but possessing the other biological activities, could be isolated. The active biological principles appear to be protein in nature. The possible role of the described biological activities in the pathogenesis of plague is discussed.",
"Virulent Yersinia species possess a common plasmid that encodes essential virulence determinants (Yops) which are regulated by the extracellular stimuli Ca2+ and temperature. The V antigen operon was recently shown to be involved in the Ca2(+)-regulated negative pathway (A. Forsberg and H. Wolf-Watz, Mol. Microbiol. 2:121-133, 1988). We show here that the V antigen-containing operon of Yersinia pseudotuberculosis is a polycistronic operon having the gene order lcrGVH-yopBD. DNA sequencing analysis of lcrGVH revealed a high homology to the corresponding genes of Yersinia pestis. LcrG was conserved and LcrH showed only one amino acid difference, while LcrV showed only 96.6% identity. The amino acid substitutions of LcrV occurred in the central domain of the protein, while the two ends of the protein were conserved. Northern (RNA) blotting experiments showed that the operon is regulated at the transcriptional level by the extracellular stimuli temperature and calcium. One 4.6-kb transcriptional product of the operon was identified. This mRNA is rapidly processed at its 5' end, resulting in different mRNA species of variable stability. By genetic analysis, the lcrV and lcrH gene products were found to be regulatory proteins having important roles in the Ca2(+)-controlled regulation of Yop expression. The activity of LcrH is modulated by a gene product of the operon that inhibits the negative action of LcrH on yop transcription in the absence of Ca2+.",
"It has previously been shown that the plasmid-encoded YopE protein of Yersinia pseudotuberculosis is a virulence determinant. In this study, HeLa cells, macrophages and mice were used as different model systems to determine the actual role of YopE in the virulence process. The YopE protein mediates a cytotoxic response on a confluent layer of HeLa cells. A prerequisite of this activity is that the pathogen binds to the cell surface. YopE also induces a cytotoxic response on mouse macrophages where it influences the ability of the pathogen to resist phagocytosis. Bacterial mutants defective in their ability to express YopE are avirulent after oral or intraperitoneal infection but virulent following intravenous injection. On the basis of these results, we propose a role for YopE in the virulence process of Yersinia.",
"The product of the lon gene in Escherichia coli, protease La, plays an important role in the degradation of abnormal proteins. To determine whether the presence of abnormal proteins stimulates expression of this gene, we examined its transcription using a lon-lacZ operon fusion. After the cells synthesized large amounts of aberrant polypeptides (e.g. following incorporation of the arginine analog, canavanine, or production of incomplete proteins with puromycin, or induction of translational errors with streptomycin), these cells showed a two- to threefold increase in lon--lacZ expression. Furthermore, synthesis of a single cloned protein, e.g. human tissue plasminogen activator, caused a similar increase in lon transcription. This induction of lon by abnormal proteins requires the heat shock regulatory gene htpR and was not seen in htpR- cells. Under these various conditions, other heat shock proteins were also induced. Thus, the appearance of aberrant cell proteins may be a common signal under many adverse conditions for the induction of cell protease (or proteases) and other heat shock proteins."
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Activation of myogenic differentiation by ectopic expression of the bovine homolog bmyf.
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myf5 is one of a family of four myogenic determination genes that control skeletal muscle differentiation. To study the role of myf5 in vivo, we generated transgenic mice harboring the bovine homolog, bmyf, under control of the murine sarcoma virus promoter. Ectopic expression of the full-length bmyf transgene was detected in brain and heart tissue samples of F1 progeny from transgenic founder mice. Ectopic bmyf expression activated endogenous skeletal myogenic determination genes in the hearts and brains of transgenic animals. Incomplete skeletal myogenesis in most hearts gave rise to cardiomegaly and focal areas of cardiomyopathy. In brains in which ectopic expression led to a more complete myogenesis, focal areas of multinucleated, striated myotubes containing actin, desmin, and myosin were observed. These unexpected results show that myf5 can initiate myogenic differentiation in vivo, supporting the hypothesis that myf5 is responsible for determination of cells to the myogenic lineage in normal embryogenesis.
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"Differentiation of skeletal myoblasts is accompanied by induction of a series of tissue-specific genes whose products are required for the specialized functions of the mature muscle fiber. The program for myogenic differentiation is subject to negative control by several peptide growth factors and by the products of mutationally activated ras oncogenes, which persistently activate intracellular cascades normally triggered by specific growth factors. Previously, we reported that induction of the muscle creatine kinase (mck) gene during myogenesis was dependent on a distal upstream enhancer that cooperated with a proximal promoter to direct high levels of expression in developing muscle cells (E. A. Sternberg, G. Spizz, W. M. Perry, D. Vizard, T. Weil, and E. N. Olson, Mol. Cell. Biol. 8:2896-2909). To investigate the mechanisms whereby ras blocks the induction of muscle-specific genes, we have examined the ability of mck 5' regulatory elements to direct expression of the linked reporter gene for chloramphenicol acetyltransferase (cat) in C2 myoblasts bearing mutant N-ras and H-ras oncogenes. In this paper we report that expression of activated ras alleles abolishes activity of the mck upstream enhancer but does not affect the activity of the mck promoter. The ability of ras to repress the expression of mck-cat fusion genes that have been transfected either transiently or stably into myoblasts suggests that ras may exert its effects on muscle-specific genes through mechanisms independent of chromatin configurations or DNA methylation. These results also suggest that ras blocks establishment of the myogenic phenotype by preventing the accumulation of regulatory factors required for transcriptional induction of muscle-specific genes.",
"Myogenic differentiation can be inhibited by the adenovirus E1a protein in the rat L6 muscle cell line. The present investigation provides evidence that E1a interferes with the expression of myogenin and the activity of Myf-5, the two myogenic helix-loop-helix (HLH) proteins that are expressed in L6 muscle cells. In nuclei of E1a-expressing L6 cells, Myf-5 protein accumulates to normal or even elevated levels and shows no alterations of its ability to bind to the DNA-binding site (CANNTG). However, trans-activation of muscle-specific reporter genes by Myf-5 is strongly inhibited. The same inhibition by E1a can be shown for the other myogenic HLH proteins, MyoD, myogenin, and MRF4/Myf-6, that have been expressed in 10T1/2 fibroblasts. In contrast to the normal level of Myf-5 expression, synthesis of myogenin is entirely abolished in the differentiation-defective L6-E1a cells. Here, we demonstrate that the carboxy-terminal trans-activator domain and probably the basic-HLH (bHLH) region of Myf-5 constitute targets for the inhibition by E1a. The effect of E1a depends on its intact transforming regions but not on the transcriptional activator domain. Our data suggest that activation of myogenin gene expression and the establishment of the differentiated phenotype may require functional Myf-5. Expression of the Myf-5 gene, however, is apparently independent of auto- or cross-regulation by the myogenic HLH proteins.",
"We have isolated the cDNA encoding a novel human myogenic factor, Myf-5, by weak cross-hydridization to the mouse MyoD1 probe. Nucleotide sequence analysis and the identification of the corresponding gene indicate that human Myf-5 is a member of a small gene family which also contains the human homologue to MyoD1. Although structurally related to the mouse factor, the human Myf-5 constitutes a different protein which nevertheless is capable of inducing the myogenic phenotype in embryonic C3H mouse 10T1/2 'fibroblasts'. The existence of more than one MyoD1-like protein in human skeletal muscle is further suggested by the detection of several similar but distinct cDNA clones. The phenotypic conversion of 10T1/2 cells by the human factor is recognized by the capacity of the cells to form multinucleated syncytia and synthesize sarcomeric myosin heavy chains. Moreover, transient expression of Myf-5 in 10T1/2 cells leads to the activation of a co-transfected muscle-specific CAT reporter gene which by itself is transcriptionally silent in the non-muscle cell background. The deduced amino acid sequence of clone Myf-5 reveals a region which is highly similar to myc proteins and the developmental factors from Drosophila encoded by the achaete scute locus and the twist gene. The myc homology region and a preceding cluster of basic amino acids are located in a larger sequence domain with strong similarity to the mouse myogenic factor MyoD1. Two additional short segments with high serine and threonine content are conserved between the two proteins.(ABSTRACT TRUNCATED AT 250 WORDS)",
"The Myf-6 gene, a novel member of the human gene family of muscle determination factors has been detected by its highly conserved sequence coding for a putative helix-loop-helix domain. This sequence motif is a common feature of all Myf factors and other regulatory proteins. The new Myf gene is located on human chromosome 12, approximately 6.5 Kb upstream of the Myf-5 locus in a closely linked cluster of myogenic determination genes. Myf-6 cDNAs were isolated from human and mouse skeletal muscle, the only tissue in which expression of the corresponding mRNA was observed. In contrast to human primary muscle cell cultures which express moderate levels of Myf-6 mRNA, most established rodent muscle cell lines completely lack this mRNA. Myogenic 10T1/2 cells, however, induced by the expression of either pEMSV-Myf-4 or pEMSV-Myf-5 activate their endogenous mouse Myf-6 gene. Constitutive expression of Myf-6 cDNA in C3H 10T1/2 fibroblasts establishes the muscle phenotype at a similar frequency to the previously characterized myogenic factors. Moreover, muscle-specific CAT reporter constructs containing either the human myosin light chain (MLC) enhancer or the promoter of the embryonic myosin light chain gene are activated in NIH 3T3 fibroblasts or in CV1 kidney cells by cotransfection of Myf-6 expression vehicles. This transcriptional activation occurs in the absence of any apparent conversion of the cellular phenotype of the recipient cells. Glutathione-S-transferase fusion proteins with Myf-3, Myf-4 or Myf-5 specifically bind to a MEF-like consensus sequence present in the human MLC enhancer and the MLC1 emb promoter. In contrast, the Myf-6 hybrid protein interacts weakly with the same sequences showing lower affinity and reduced specificity. Since co-expressed pEMSV-Myf-6, nevertheless, is able to activate transcription of the MLC-CAT reporter constructs in non-muscle tissue culture cells, the different DNA binding properties in vitro might suggest that transactivation of gene expression by Myf-6 involves distinct binding sites and/or additional protein factors.",
"Stable myogenic cell lines have been derived at a high frequency by transfection of a cloned multipotential mouse embryo cell line, C3H 10T1/2, with cloned human DNA linked to a selectable neomycin resistance gene. The myogenic phenotype remains linked to neomycin resistance during secondary transfections. Although proliferative in growth conditions, these cell lines maintain the ability to differentiate and express muscle-specific proteins. We conclude that there is a simple genetic basis for myogenic determination and that a single gene, myd, converts 10T1/2 cells to a myoblast lineage. Southern blot analysis demonstrates nonidentity of myd and the MyoD1 gene. Northern blot analysis shows that myd-transfected myogenic lineages express MyoD1 mRNA while parental 10T1/2 cells do not. These results suggest that a dependent regulatory gene pathway mediates myogenic determination and differentiation.",
"Transfection of cDNA expression vectors encoding either MyoD1 or myogenin into 10T1/2 cells converts them to myogenic cells. We show that transfection of 10T1/2 cells with the MyoD1 cDNA activates expression of endogenous MyoD1 mRNA, indicating that MyoD1 is subject to positive autoregulation. This activation of endogenous MyoD1 mRNA was also observed in Swiss 3T6 cells, but not in several other fibroblast or adipoblast cell lines transfected with the MyoD1 cDNA. In addition, transfection of the MyoD1 cDNA leads to activation of myogenin expression, and transfection of the myogenin cDNA leads to activation of MyoD1 expression. Thus, MyoD1 and myogenin appear to function in a positive autoregulatory loop that could either: account for or contribute to the stability of myogenic commitment; or amplify the level of expression of both MyoD1 and myogenin above a critical threshold that is required for activation of the myogenic program.",
"cDNA libraries are a potential source of DNA probes which can be used to screen for restriction fragment length polymorphisms (RFLPs). This approach had not been exploited until recently; in this and another paper (Balazs et al. 1984) we show that they can be fruitful source for such probes. As an example herein we describe a common EcoRI polymorphism, detected by a randomly selected cDNA probe of unknown function. This sequence has been mapped to human chromosome 12, band q21, through the combined use of somatic cell genetics, DNA recombinant technology, and in situ hybridization."
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Identification of bovine rotavirus serotypes G1, G2, G3, and G11 from diarrheic calves.
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On the basis of antigenic variability in the VP7 outer capsid glycoprotein, at least 14 G serotypes exist for group A rotaviruses. Serotypic diversity exists among bovine rotaviruses (BRV), with serotypes G1, G6, G8, and G10 reported for cattle. Although G1 and G8 rotaviruses were originally described for humans, the recent isolation of G6 and G10 rotaviruses from humans further emphasizes the serotypic similarity between human and bovine rotaviruses and the possible zoonotic potential of rotaviruses. Results of our previous studies have indicated that more than 24% of BRV-positive field samples from diarrheic calves were nonreactive with cDNA probes or monoclonal antibodies to serotypes G6, G8, and G10. In this study, cDNA probes were prepared by polymerase chain reaction amplification of the hyperdivergent regions of the VP7 genes (nucleotides 51 to 392) from human (G1, G2, and G3) and porcine (G4, G5, and G11) rotaviruses. These probes were used in a dot blot hybridization assay to further characterize the G types of 59 BRV strains (fecal samples from diarrheic calves in Ohio, Nebraska, Washington, and South Dakota) that were nonreactive with cDNA probes to G6, G8, and G10. Rotaviruses belonging to serotypes G1 (n = 7), G2 (n = 1), G3 (n = 2), and G11 (n = 3) were identified among the BRV field samples. The BRV associated with these G types accounted for 22% of the samples tested; the other 78% of these samples remained untypeable with these probes. To our knowledge, this is the first report in the United States of the identification among BRV isolates of rotavirus serotypes G1, G2, G3, and G11.
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[
"Equine rotavirus FI23 was shown to be prototypic of a novel G serotype, provisionally G14, by cross-neutralization and VP7 sequence determination. Although distinct, there are as few as six differing amino acid residues (92, 94, 96, 146, 147, and 221) in the VP7 antigenic regions of FI23 and G3 rotaviruses.",
"The bovine UK and simian SA11 rotaviruses are commonly used VP7-type reference strains. Since the surface protein VP3 is a significant neutralization antigen, it is important to fully characterize the VP3 types associated with current reference strains. Here we present the complete nucleotide and predicted amino acid sequence of VP3 from UK rotavirus (VP7 type 6) and compare it to the published sequences of SA114fm and RV-5. We also compare the deduced amino acid sequence covering the trypsin cleavage region of UK VP3 to 25 other available sequences. The UK protein is clearly different from that of bovine NCDV (another commonly used VP7 type 6 strain) and represents a second VP3 type associated with bovine rotaviruses. Our SA11 sequence differs from that determined by Lopez et al. [1985, Virology 144, 11-19; later referred to as SA114fM by Lopez et al. (1986, Virology 154, 224-227], their sequence being very similar to the published sequence of NCDV VP3. The significance of these results with regard to virus serotypes is discussed. Finally, in analyzing the nucleotide sequence surrounding the initiation codon, a potential hairpin-loop structure was identified which may be involved in translational regulation.",
"Knowledge of the structure and function of the genes and proteins of the rotaviruses has expanded rapidly. Information obtained in the last 5 years has revealed unexpected and unique molecular properties of rotavirus proteins of general interest to virologists, biochemists, and cell biologists. Rotaviruses share some features of replication with reoviruses, yet antigenic and molecular properties of the outer capsid proteins, VP4 (a protein whose cleavage is required for infectivity, possibly by mediating fusion with the cell membrane) and VP7 (a glycoprotein), show more similarities with those of other viruses such as the orthomyxoviruses, paramyxoviruses, and alphaviruses. Rotavirus morphogenesis is a unique process, during which immature subviral particles bud through the membrane of the endoplasmic reticulum (ER). During this process, transiently enveloped particles form, the outer capsid proteins are assembled onto particles, and mature particles accumulate in the lumen of the ER. Two ER-specific viral glycoproteins are involved in virus maturation, and these glycoproteins have been shown to be useful models for studying protein targeting and retention in the ER and for studying mechanisms of virus budding. New ideas and approaches to understanding how each gene functions to replicate and assemble the segmented viral genome have emerged from knowledge of the primary structure of rotavirus genes and their proteins and from knowledge of the properties of domains on individual proteins. Localization of type-specific and cross-reactive neutralizing epitopes on the outer capsid proteins is becoming increasingly useful in dissecting the protective immune response, including evaluation of vaccine trials, with the practical possibility of enhancing the production of new, more effective vaccines. Finally, future analyses with recently characterized immunologic and gene probes and new animal models can be expected to provide a basic understanding of what regulates the primary interactions of these viruses with the gastrointestinal tract and the subsequent responses of infected hosts.",
"Rotaviruses with genome rearrangements isolated from a chronically infected immunodeficient child (F. Hundley, M. McIntyre, B. Clark, G. Beards, D. Wood, I. Chrystie, and U. Desselberger, J. Virol 61:3365-3372, 1987) are the first recognized human isolates of serotype 10. This was shown by both a direct enzyme-linked immunosorbent assay and virus neutralization assays using serotype specific monoclonal antibodies. The serotype was confirmed by sequence analysis of the gene encoding VP7, which revealed a 96% amino acid homology to the bovine serotype 10 isolate B223.",
"Cross neutralization tests with a panel of rotavirus strains representing previously described nine VP7 (G) serotypes revealed that bovine rotavirus strain KK-3, a prototype Japanese bovine serotype 2, belonged to a new serotype (G10), confirming and extending the recent report of Snodgrass et al. [J. Clin. Microbiol. 28: 504-507 (1990)] which showed that hyperimmune serum to the KK-3 strain neutralized the B223 strain, a proposed type strain of G10. Further antigenic characteristics of the KK-3 strain, as well as the 0510 strain (a G6 strain isolated in Japan), were examined in terms of their VP4 (P) specificity. For the characterization of P types, we employed genetic reassortants that possess VP4 gene for UK and VP7 gene for D (G1), VP4 gene for NCDV and VP7 gene for SA11 (G3), or VP4 gene for SA11 and VP7 gene for NCDV (G6) in the plaque reduction neutralization assay with hyperimmune sera against these two Japanese strains and the prototype bovine rotavirus NCDV strain. While the 0510 strain had UK-like P and NCDV-like G types, the KK-3 strain had a distinct set of P and G types. Thus, at least three P types (NCDV-, UK-, and KK-3-like) and two G types (G6 and G10) are present among bovine rotavirus strains.",
"Japanese bovine rotavirus isolates, which fall into two different serotypes, were shown to belong to subgroup I and to have long RNA electrophoretypes. This study confirmed the distinction of two serotypes on the basis of a greater than 20-fold difference in neutralization titres between the homologous and heterologous reactions; however, significant one-way cross-neutralization was observed between one of the strains with bovine serotype 2 and antisera to strains with bovine serotype 1 (serotype 6 according to the unified serotyping system). When 32P-labelled transcription probes prepared from Japanese strains as well as a prototype NCDV strain were hybridized with genomic double-stranded RNA from these bovine strains and from prototype human strains, a high level of homology was observed among bovine rotavirus strains; but this level of homology was not found between bovine strains and any of the prototype human strains. These results suggest that bovine rotavirus strains belong to a single genogroup that is distinct from any of the human genogroups previously identified by RNA-RNA hybridization.",
"Two group A, subgroup I, rotavirus strains possessing \"super short\" RNA patterns were adapted to growth in MA-104 cells. Both produced marked cytopathic effect in primary culture. Reciprocal cross-neutralization titers, polypeptide analysis, and the serum neutralizing antibody response of an infected child suggested that super short viruses are serotypically distinct from the four recognized human serotypes."
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Expression of the surface layer protein of Lactobacillus acidophilus ATCC 4356.
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The cell surfaces of several Lactobacillus species are covered by a regular layer composed of a single species of protein, the S-protein. The 43-kDa S-protein of the neotype strain Lactobacillus acidophilus ATCC 4356, which originated from the pharynx of a human, was purified. Antibodies generated against purified S-protein were used to screen a lambda library containing chromosomal L. acidophilus ATCC 4356 DNA. Several phages showing expression of this S-protein in Escherichia coli were isolated. A 4.0-kb DNA fragment of one of those phages hybridized to a probe derived from an internal tryptic fragment of the S-protein. The slpA gene, coding for the surface layer protein, was located entirely on the 4.0-kb fragment as shown by deletion analysis. The nucleotide sequence of the slpA gene was determined and appeared to encode a protein of 444 amino acids. The first 24 amino acids resembled a putative secretion signal, giving rise to a mature S-protein of 420 amino acids (44.2 kDa). The predicted isoelectric point of 9.4 is remarkably high for an S-protein but is in agreement with the data obtained during purification. The expression of the entire S-protein or of large, C-terminally truncated S-proteins is unstable in E. coli.
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[
"The effect of growth temperature on the loss of virulence of the fish pathogen Aeromonas salmonicida was investigated. Three virulent strains were grown in Trypticase soy broth at temperatures ranging from 22 to 30 degrees C. Growth at a higher-than-optimal temperature (26 to 27 degrees C for the three strains studied) resulted in the selection of spontaneous attenuated derivatives in the initial bacterial population. For example, virulent bacteria represented less than 10% of the population of a culture grown at 30 degrees C, and attenuated derivatives were easily isolated by streaking the culture on solid medium and picking single colonies. Virulent strains autoaggregated during growth and possessed a cell wall layer (A-layer) external to the outer membrane, as previously described. Attenuated strains did not autoaggregate and did not possess the A-layer. The A-layer apparently shielded bacteriophage receptors and a mannose-specific yeast agglutinin located in the outer membrane. Thus, virulent strains exhibited impaired adsorption of phages, whereas attenuated strains were phage sensitive. Furthermore, attenuated strains agglutinated yeast cells but virulent strains did not. The attenuated strains had higher maximum growth temperatures than their virulent parent strains, and this accounts for their selection at high temperatures. It is proposed that the A-layer contributes significantly to the physical properties of the A. salmonicida cell envelope and that these physical properties of the A. salmonicida cell envelope and that these physical change upon loss of the A-layer to permit growth at a higher-than-usual temperature.",
"Thin sections, freeze-etched, and negatively stained preparations of Methanocorpusculum sinense cells reveal a highly lobed cell structure with a hexagonally arranged surface layer (S layer). Digital image processing of negatively stained envelope fragments show that the S layer forms a porous but strongly interconnected network. Since the S layer is the exclusive cell envelope component outside the cytoplasmic membrane it must have a cell shape determining and maintaining function. Although lattice faults such as disclinations and dislocations are a geometrical necessity on the surface of a closed protein crystal, our data indicate that they also play important roles as sites for the incorporation of new morphological units, in the formation of the lobed cell structure, and in the cell division process. In freeze-etched preparations of intact cells numerous positive and negative 60 degree wedge disclinations can be detected which form pentagons and heptagons in the hexagonal array. Complementary pairs of pentagons and heptagons are the termination points of edge dislocations. They can be expected to function both as sites for incorporation of new morphological units into the lattice and as initiation points for the cell division process. The latter is determined by the ratio between the increase of protoplast volume and the increase in actual S-layer surface area during cell growth. We postulate that this mode of cell fission represents a common feature in lobed archaebacteria which possess an S layer as the exclusive wall component.",
"Cells of the nonhelical strain of Spiroplasma citri underwent changes of morphology comparable to those which occurred in the normal helical strain. Cells of the nonhelical strain had the same ultrastructural features as helical cells and released long flexible fibrils similar to those seen in other spiroplasmas. Nonhelical organisms showed an increased tendency to aggregate, forming cell clusters of an unusual annular form. The cytoplasmic membrane of the nonhelical strain lacked a single protein present in all helical strains. Loss of helicity associated with the senescence of spiroplasma cells was not accompanied by the disappearance of this protein. Differences in colony morphology were shown to be a consequence of motility, and a technique was developed which facilitated the identification of nonmotile organisms.",
"Since bacteria are so small, microscopy has traditionally been used to study them as individual cells. To this end, electron microscopy has been a most powerful tool for studying bacterial surfaces; the viewing of macromolecular arrangements of some surfaces is now possible. This review compares older conventional electron-microscopic methods with new cryotechniques currently available and the results each has produced. Emphasis is not placed on the methodology but, rather, on the importance of the results in terms of our perception of the makeup and function of bacterial surfaces and their interaction with the surrounding environment.",
"A gene bank of DNA from the fish pathogenic bacterium Aeromonas salmonicida was constructed in the bacteriophage lambda gt11. Phage lambda gt11/10G, a recombinant carrying a 4.0-kilobase fragment of A. salmonicida DNA, was found to express the surface array protein (A protein) in Escherichia coli. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the protein expressed from the cloned gene had a subunit molecular weight of 49,000, which was identical to that of subunits in the native assembled A layer. Genomic Southern analysis showed that the gene coding for this predominant cellular protein was in a single copy on the chromosome and was conserved among a wide range of A. salmonicida strains with different phenotypic characteristics and isolated from diverse geographic locations, fish species, and means of pathogenesis. Results of genomic blotting experiments also showed that loss of expression of the A layer resulting from growth at 30 degrees C was accompanied by genetic rearrangement in which N-terminal sequences of the gene for A protein were lost by deletion."
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Immunological mechanisms of filarial antigen-specific anergy in patients with lymphatic filariasis.
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The immunological mechanisms involved in maintenance of an asymptomatic microfilaremic state (MF) in patients with lymphatic filariasis remain undefined. MF patients have impaired filarial antigen (Ag)-specific lymphocyte proliferation and decreased frequencies (Fo) of Ag-specific T cells, and yet elevated serum IgE and antifilarial IgG4. To investigate the mechanism of Ag-specific anergy in MF patients in contrast to amicrofilaremic individuals with chronic lymphatic obstruction (CP), the Fo of Ag-specific lymphocytes from peripheral blood mononuclear cells secreting either IL-4 or IFN-gamma were assessed by filter spot enzyme-linked immunosorbent assay, and IL-10 and transforming growth factor-beta (TGF-beta) mRNA transcript levels were assessed by a semiquantitative reverse transcriptase polymerase chain reaction technique. The Fo of filaria-specific IL-4-secreting lymphocytes were equivalent in both MF (geometric mean [GM] = 1:11,700) and CP (GM = 1:29,300 P = 0.08), whereas the Fo of IFN-gamma-secreting lymphocytes were lower in MF (GM = 1:39,300) than in CP (GM = 1:4,200, P < 0.01). When the ratio of IL-4/IFN-gamma (T helper type 2 [Th2]/Th1)-secreting cells was examined, MF subjects showed a predominant Th2 response (8:1) compared with a Th1 response in CP individuals (1:4). mRNA transcript levels of IL-10 were also significantly elevated in MF compared with CP individuals (P < 0.01). Further, IL-10 and TGF-beta were shown to have a role in modulating the Ag-specific anergy among MF subjects, in that neutralizing anti-IL-10 or anti-TGF-beta significantly enhanced lymphocyte proliferation response (by 220-1,300%) to filarial Ags in MF individuals. These findings demonstrate that MF subjects respond to parasite antigen by producing a set of suppressive cytokines that may facilitate persistence of the parasite within humans while producing little clinical disease.
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"Interleukin 10 (IL-10) and viral IL-10 (v-IL-10) strongly reduced antigen-specific proliferation of human T cells and CD4+ T cell clones when monocytes were used as antigen-presenting cells. In contrast, IL-10 and v-IL-10 did not affect the proliferative responses to antigens presented by autologous Epstein-Barr virus-lymphoblastoid cell line (EBV-LCL). Inhibition of antigen-specific T cell responses was associated with downregulation of constitutive, as well as interferon gamma- or IL-4-induced, class II MHC expression on monocytes by IL-10 and v-IL-10, resulting in the reduction in antigen-presenting capacity of these cells. In contrast, IL-10 and v-IL-10 had no effect on class II major histocompatibility complex (MHC) expression on EBV-LCL. The reduced antigen-presenting capacity of monocytes correlated with a decreased capacity to mobilize intracellular Ca2+ in the responder T cell clones. The diminished antigen-presenting capacities of monocytes were not due to inhibitory effects of IL-10 and v-IL-10 on antigen processing, since the proliferative T cell responses to antigenic peptides, which did not require processing, were equally well inhibited. Furthermore, the inhibitory effects of IL-10 and v-IL-10 on antigen-specific proliferative T cell responses could not be neutralized by exogenous IL-2 or IL-4. Although IL-10 and v-IL-10 suppressed IL-1 alpha, IL-1 beta, tumor necrosis factor alpha (TNF-alpha), and IL-6 production by monocytes, it was excluded that these cytokines played a role in antigen-specific T cell proliferation, since normal antigen-specific responses were observed in the presence of neutralizing anti-IL-1, -IL-6, and -TNF-alpha mAbs. Furthermore, addition of saturating concentrations of IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha to the cultures had no effect on the reduced proliferative T cell responses in the presence of IL-10, or v-IL-10. Collectively, our data indicate that IL-10 and v-IL-10 can completely prevent antigen-specific T cell proliferation by inhibition of the antigen-presenting capacity of monocytes through downregulation of class II MHC antigens on monocytes.",
"Our observations on the cellular immune response to type-A influenza suggest the existence of two distinct pathways of protein antigen presentation to T lymphocytes. One of these pathways is involved with presentation of antigens introduced into the presenting cell from without. This exogenous presentation pathway is the well-recognized route of presentation of soluble and particulate antigens to T lymphocytes. This pathway probably involves uptake of antigen into endocytic vesicles, alteration of antigen within an intracellular compartment, and subsequent display of antigen on the presenting cell surface (Unanue 1984). The second pathway is one which we have tentatively designated as an endogenous presentation pathway. The constraints on this pathway have yet to be fully defined. At a minimum, this pathway appears to involve the presentation of antigens which are synthesized de novo in the presenting cell utilizing the cell's biosynthetic machinery. This pathway may also handle preformed antigens located within the cytosolic compartment of the presenting cell. Perhaps the most striking feature of these two antigen presentation pathways is the close association between the MHC restriction of an antigen-specific T lymphocyte and the pathway of antigen presentation to that T lymphocyte. Our data suggest that this association holds both at the effector level and at the level of induction of T lymphocytes. Thus, presentation of a given antigen by the endogenous pathway preferentially triggers a response from class I MHC-restricted T lymphocytes directed to that antigen. The molecular basis for this link of class I MHC-restriction to the endogenous pathway and MHC class II restriction to the exogenous pathway is unknown. It seems likely that interactions between MHC molecules and antigen within the presenting cell may be critical for the demarcation of these pathways. Thus, for example, antigen presented by the endogenous route may only be able to associate intracellularly with newly synthesized or recycling class I MHC molecules. An understanding of the molecular basis of this phenomenon will require detailed information on the expression, intracellular trafficking, and transport of class I and class II MHC molecules in the antigen-presenting cell. An unresolved issue, at least in the case of viral antigens, is the nature and form of the antigenic moieties presented by the exogenous and endogenous pathways. In the case of viral antigen presentation to class II MHC-restricted T lymphocytes, there is strong, albeit indirect, evidence for processing of antigen and recognition of fragments of viral polypeptides (Lamb et al. 1982, Hackett et al. 1983).(ABSTRACT TRUNCATED AT 400 WORDS)",
"In order to assess the immunodiagnostic utility of FST skin test antigen purified from Dirofilaria immitis, skin test responses were analyzed in 177 inhabitants of a South Pacific island hyperendemic for Wuchereria bancrofti filariasis. Although the distribution of immediate hypersensitivity skin test responses was similar to those found in other filarial endemic populations, individual immediate skin test reactions lacked the sensitivity and specificity to identify those with microfilaremia or those with any clinical or parasitologic evidence of filarial disease. Delayed hypersensitivity type skin test reactions were elicited by the antigen in 60% of people but again these delayed cutaneous reactions did not correlate with the presence or absence of stigmata of filariasis. These findings document the limitation of this antigen preparation in the immunodiagnosis of filariasis in residents of an endemic area.",
"We have demonstrated the existence of human cytokine synthesis inhibitory factor (CSIF) [interleukin 10 (IL-10)]. cDNA clones encoding human IL-10 (hIL-10) were isolated from a tetanus toxin-specific human T-cell clone. Like mouse IL-10, hIL-10 exhibits strong DNA and amino acid sequence homology to an open reading frame in the Epstein-Barr virus, BCRFI. hIL-10 and the BCRFI product inhibit cytokine synthesis by activated human peripheral blood mononuclear cells and by a mouse Th1 clone. Both hIL-10 and mouse IL-10 sustain the viability of a mouse mast cell line in culture, but BCRFI lacks comparable activity in this assay, suggesting that BCRFI may have conserved only a subset of hIL-10 activities.",
"Parasitic helminths typically induce components of immediate-type hypersensitivity, including elevated serum IgE, eosinophilia, and mucosal mast cells. These responses are T-cell-dependent and associated with rapid expulsion of parasitic worms from a sensitized host; existing experimental systems have failed to define the precise role of cytokines in these responses. We report here that anti-interleukin 4 or anti-interleukin 4 receptor antibodies block the polyclonal IgE response to a parasitic nematode, Heligmosomoides polygyrus, and abrogate protective immunity to the infection. In contrast, anti-interleukin 5 antibody prevented H. polygyrus-induced eosinophilia but did not prevent protection. These data provide evidence that a specific cytokine affects the physiology and survival of a parasitic nematode in the host.",
"The immunological mechanisms underlying the susceptibility to disseminated visceral parasitism of mononuclear phagocytes in patients with kala-azar remain undefined. Resistance and susceptibility are correlated with distinct patterns of cytokine production in murine models of disseminated leishmanial disease. To assess lesional cytokine profiles in patients with kala-azar, bone marrow aspirates were analyzed using a quantitative reverse transcriptase PCR technique to amplify specific mRNA sequences of multiple Th1-, Th2-, and/or macrophage-associated cytokines. Transcript levels of IL-10 as well as IFN-gamma were significantly elevated in patients with active visceral leishmaniasis; IL-10 levels decreased markedly with resolution of disease. These findings suggest that IL-10, a potent, pleiotropic suppressor of all known microbicidal effector functions of macrophages, may contribute to the pathogenesis of kala-azar by inhibiting the cytokine-mediated activation of host macrophages that is necessary for the control of leishmanial infection.",
"The H-2-compatible mouse strains, AKR and B10.BR, exhibit disparate responses to infection with the parasitic nematode Trichinella spiralis. The resistant AKR mice expel intestinal adult worms faster than susceptible B10.BR mice. We tested antibody and lymphokine responses in these strains. With respect to antibody responses, the B10.BR mice had 3- to 10-fold more serum IgE and T. spiralis-specific IgG1 and IgA than AKR mice. The B10.BR mice also had greater numbers of IgG and IgA plaque-forming cells than AKR mice. In contrast, AKR mice produced T. spiralis-specific IgG2a, whereas the B10.BR mice did not. The antibody response kinetics of these strains were similar. We also analyzed lymphokine secretion after restimulating lymphocytes in vitro with T. spiralis Ag. The AKR mesenteric lymph node cells produced more IFN-gamma and less IL-4 than the B10.BR mesenteric lymph node cells. The B10.BR splenocytes produced more IL-4 than the AKR splenocytes, although splenocyte IFN-gamma production was not different. The kinetics of IL-4 production also differed between the two strains. In summary, resistant AKR mice produced more IFN-gamma and T. spiralis-specific IgG2a than susceptible B10.BR mice, which produced more IL-4, IgE, and T. spiralis-specific IgG1. Our results are consistent with differential activation of Th cell subsets in T. spiralis-infected AKR and B10.BR mice."
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Methylation of the metallothionein I promoter suppresses the human testis-specific lactate dehydrogenase transgene in somatic tissues
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Mice carrying a chimeric transgene of the human testis-specific lactate dehydrogenase cDNA driven by mouse metallothionein I promoter have been reported to express the transgene in a testis-specific manner in six founder lines. To study the mechanism by which this testis-specific expression is mediated, we have examined genomic placement, expression pattern, and methylation status of the transgene. Our results indicate that transgene expression is repressed in all somatic tissues examined even when heavy metals are administered. Nuclear run-on assays indicate that failure of expression in the liver (in which the metallothionein I promoter is highly active) occurs at the transcriptional level. In contrast, the transgene mRNA is transcribed in male germ cells and is developmentally regulated during spermatogenesis. Examination of the transgene methylation status reveals that expression is inversely correlated with hypermethylation of the locus; all CpG dinucleotides examined in the promoter region were found to be fully methylated in kidney and liver but were undermethylated in testis. Since methylation of the murine metallothionein I promoter is sufficient to inhibit its activity, it is likely that suppression of the transgene in somatic tissues is mediated by methylation.
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"The preparation and use of a specific cDNA probe for quantitating mRNA by solution hybridization is described. Cloned DNA sequences are nick translated, denatured, hybridized to single-stranded M13 clones containing message strand (mDNA) sequences, and separated chromatographically on Bio-Gel A50 under first native and then denaturing conditions to yield a single-stranded cDNA probe. The details of a solution hybridization assay in which the single-stranded cDNA is used to quantitate mRNA in total nucleic acid samples are described. As little as 0.5 pg of mRNA can easily be detected within a day of sample isolation. Thus, the assay is both rapid and sensitive and can be used to measure RNAs complementary to any cloned DNA sequence. It is ideally suited to situations when accurate quantitation of multiple samples is anticipated.",
"The nucleotide sequences of three nonallelic human genomic DNA fragments which each contain one member of the growth hormone gene family are presented. These genes code for the known polypeptide hormones, growth hormone (hGH), chorionic somatomammotropin (hCS), and a yet unknown protein which differs from hGH in 13 positions. Each gene is structured into five exons, the four introns occurring at identical positions. Reflecting recent gene divergence, 90-95% sequence homology is seen in exons, introns, 5', and immediate 3' nontranscribed regions. The regions downstream of the polyadenylation sites in the genes for hGH and its variant, but not for hCS, contain members of an Alu family repeat sequence.",
"The anterior pituitary gland, which is derived from a common primordium originating in Rathke's pouch, contains phenotypically distinct cell types, each of which express discrete trophic hormones: adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), prolactin, growth hormone, and follicle stimulating hormone (FSH)/luteinizing hormone (LH). The structurally related prolactin and growth hormone genes, which are evolutionarily derived from a single primordial gene, are expressed in discrete cell types--lactotrophs and somatotrophs, respectively--with their expression virtually limited to the pituitary gland. The pituitary hormones exhibit a temporal pattern of developmental expression with rat growth hormone and prolactin characteristically being the last hormones expressed. The reported co-expression of these two structurally related neuroendocrine genes within single cells prior to the appearance of mature lactotrophs, in a subpopulation of mature anterior pituitary cells, and in many pituitary adenomas raises the possibility that the prolactin and growth hormone genes are developmentally controlled by a common factor(s). We now report the identification and characterization of nucleotide sequences in the 5'-flanking regions of the rat prolactin and growth hormone genes, respectively, which act in a position- and orientation-independent fashion to transfer cell-specific expression to heterologous genes. At least one putative trans-acting factor required for the growth hormone genomic sequence to exert its effects is apparently different from those modulating the corresponding enhancer element(s) of the prolactin gene because a pituitary 'lactotroph' cell line producing prolactin but not growth hormone selectively fails to express fusion genes containing the growth hormone enhancer sequence.",
"Previous experiments have demonstrated that the human beta-globin gene is correctly regulated in transgenic mice. The beta-globin gene is not expressed in yolk sac-derived erythroid cells in early embryonic development but is expressed concomitantly with the adult mouse beta-globin genes in 14- to 16-day fetal liver and adult reticulocytes. In an attempt to localize sequences that direct erythroid-specific expression, fragments of the human beta-globin gene were inserted in the opposite orientation 200 base pairs (bp) upstream of an intact human A gamma marker gene, which is not expressed on its own in mouse fetal liver. In the experiments reported here, two beta-globin 3' sequences activated the marker gene specifically in fetal liver. One sequence is located in a 250-bp Pst I fragment 550-800 bp downstream from the poly(A) site; the other is located near an EcoRI site in the third exon. These two sequences are active individually, and their combined effect is greater than their effects alone. beta-Globin 5' sequences from -815 to -50 were also analyzed for activity in this assay. The 5' sequences did not activate the marker gene when tested alone but did stimulate expression that was already directed to adult erythroid tissue by the two 3' sequences. These results suggest that three separate sequences are involved in human beta-globin gene regulation. The two 3' sequences act as adult erythroid enhancers and the 5' sequence stimulates expression that is already determined to be erythroid specific.",
"Experiments were designed to test the effect of introns on gene expression in transgenic mice. Four different pairs of gene constructs, which were identical except that one member of each pair lacked all introns, were compared for expression of mRNA after introduction into the murine germ line by microinjection of fertilized eggs. The expression of two chimeric genes, made by fusing either the mouse metallothionein I or the rat elastase 1 promoter/enhancer to the rat growth hormone gene, was assayed in fetal liver or pancreas, respectively, while two natural genes, an oligonucleotide-marked mouse metallothionein I gene and the human beta-globin gene, were assayed in fetal liver. In each case there was, on average, 10- to 100-fold more mRNA produced from the intron-containing construct. Moreover, mRNA levels were proportional to the relative rates of transcription that were measured in isolated nuclei. However, when the expression of the two mouse metallothionein I gene-based constructs was tested after transfection into cultured cells, little difference was observed. These observations suggest that introns play a role in facilitating transcription of microinjected genes and that this effect may be manifest only on genes exposed to developmental influences."
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Identification of an enhancer in the muscle-specific regulatory region of the chicken myosin alkaline light-chain gene.
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Expression of MyoD, myogenin, MRF4, and Myf-5 converts nonmuscle cells to muscle cells. In an attempt to analyze the roles of these factors, we have investigated their effects on transcription driven by the promoter of the chicken myosin alkaline light-chain (MLC1) gene. The activation by CMD1 or c-myogenin (chicken MyoD or myogenin, respectively) was dependent on the existence of a muscle-specific regulatory region located from positions -2096 to -1743. Its distal half, containing a pair of E boxes (CANNTG), had been previously characterized as an enhancer responsive to CMD1 but not to c-myogenin. In this study, we report the identification of another enhancer in the muscle-specific regulatory region which is preferentially responsive to c-myogenin. Deletion and mutation analyses indicated that this enhancer requires a single E box and its flanking sequences. Furthermore, analysis of chimeric proteins of CMD1 and c-myogenin indicated that regions outside the basic helix-loop-helix domain of c-myogenin are involved in the specificity of the enhancer. These results show that CMD1 and c-myogenin act on the MLC1 gene by recognizing different upstream DNA sequences and that direct or indirect interactions between the regions outside the basic helix-loop-helix domain and flanking sequences of E boxes are involved in the target sequence specificity.
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[
"5-azacytidine treatment of mouse C3H10T1/2 embryonic fibroblasts converts them to myoblasts at a frequency suggesting alteration of one or only a few closely linked regulatory loci. Assuming such loci to be differentially expressed as poly(A)+ RNA in proliferating myoblasts, we prepared proliferating myoblast-specific, subtracted cDNA probes to screen a myocyte cDNA library. Based on a number of criteria, three cDNAs were selected and characterized. We show that expression of one of these cDNAs transfected into C3H10T1/2 fibroblasts, where it is not normally expressed, is sufficient to convert them to stable myoblasts. Myogenesis also occurs, but to a lesser extent, when this cDNA is expressed in a number of other cell lines. The major open reading frame encoded by this cDNA contains a short protein segment similar to a sequence present in the myc protein family.",
"We have isolated cDNAs encoding a chicken homologue of MRF4 (cMRF4) in addition to chicken MyoD (CMD1) and myogenin (c-myogenin) described previously. In an attempt to understand the roles that cMRF4, CMD1, and c-myogenin play in chicken myogenesis, the effects of these factors on muscle-specific cis-elements identified in regulatory regions of myosin alkali light chain (MLC) genes were examined. The promoter analysis of some of MLC genes has revealed two sorts of muscle-specific positive regulatory elements to date, an enhancer located upstream of the adult type LC1 gene and a cis-element, termed an MLC box, conserved among promoters of various MLC genes. The LC1 enhancer was exclusively trans-activated by CMD1. Although c-myogenin also activated transcription driven by the LC1 promoter, it was suggested that c-myogenin requires a cis-element(s) other than the CMD1-responsive enhancer. Chicken MRF4 could not trans-activate any of the constructs containing the LC1 promoter. In contrast, the promoter of the embryonic L23 gene was trans-activated by all of the three factors. From deletion and mutation analysis, the MLC box was shown to be involved in their positive regulation. These results extend previous observations that individual myogenic regulatory factors exhibit different capabilities in transcriptional activation of muscle-specific genes by acting distinctively upon their regulatory elements.",
"The expression of the fast type of myosin alkali light chain 1 is induced during the differentiation of muscle cells. To study the mechanism of its gene regulation, we joined the sequence of the 5'-flanking and upstream region of the chicken myosin alkali light-chain gene to the structural gene for chloramphenicol acetyltransferase (CAT). The fusion gene was introduced either into quail myoblasts transformed by a temperature-sensitive mutant of Rous sarcoma virus (tsNY68) or into chicken myoblasts, and the transiently expressed CAT activity was assayed after the differentiation of the myoblasts. From the experiments with the external and internal deletion mutants of the fusion gene, the cis-acting regulatory region responsible for the enhanced expression of the CAT activity in response to the cell differentiation was found to be localized at 2 kilobases upstream of the transcription initiation site. This region of 160 nucleotides contained two pairs of short sequences worthy of note, a direct repeat of 12 nucleotides, and an inverted repeat of 8 nucleotides. The nucleotide sequences of the 5'-flanking sequence up to nucleotide -3381 were determined and compared with those of the upstream activating elements of actin genes.",
"Helix-loop-helix proteins play important roles in developmental processes, such as myogenesis, neurogenesis, and sex determination. The gene Enhancer of split [E(spl)] of Drosophila, a member of a gene complex that is involved in early neurogenesis, encodes a protein with a basic domain and a helix-loop-helix motif. We took advantage of a dominant mutation of this gene, E(spl)D, to define in vivo structural features of this protein for proper function. The mutation renders the otherwise recessive eye phenotype of spl dominant. By germ-line transformation of different in vitro mutagenized versions of the E(spl) gene, we could demonstrate that the basic domain of this helix-loop-helix protein is functional and necessary for expression of the dominant phenotype. These results are supported by in vitro DNA-binding assays, which showed that the basic domain is in fact necessary for DNA binding, despite the presence of a proline residue. Furthermore, we could show that the dominant enhancement of spl is caused by truncation of the E(SPL)D protein in combination with deletion of a putative regulatory element."
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Functional Instability of the TonB Gene of Enterobacter aerogenes
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The tonB gene of Enterobacter aerogenes was cloned, sequenced, and expressed in Escherichia coli. It complemented an E. coli tonB mutant as efficiently as E. coli tonB, except for colicin B and D sensitivities. However, colicin B and D sensitivities were complemented by a derivative in which the aspartate at position 165 was replaced by a glutamine (TonBD-165-->Q) by site-directed mutagenesis. In E. coli, the corresponding amino acid is a glutamine (Q-160) which is known to be altered in most mutants showing suppression of the btuB451 mutation. Fourteen independent btuB451 suppressor mutations in E. aerogenes tonB which all had suffered the same point mutation resulting in a change from glycine to valine at position 239 (G-239-->V) of the C-terminal end of the protein were isolated. The mutation was located within a region which is nonessential for function of E. aerogenes TonB as well as E. coli TonB. A constructed double mutation, expressing a D-165-->Q/G-239-->V derivative, no longer acted as a btuB451 suppressor. However, it restored colicin B and D sensitivities even more efficiently than the D-165-->Q derivative. Corresponding mutations constructed in E. coli tonB, giving rise to Q-160-->D, G-234-->V, and Q-160-->D/G-234-->V derivatives, showed phenotypes comparable to the E. aerogenes mutations. We take this as evidence that at least a functional interaction between the D-165 (Q-160 in E. coli) and the G-239 (G-234 in E. coli) region is necessary for TonB function. The implications of this interaction for functional instability of TonB are discussed.
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[
"It might be anticipated that the presence of redundant but oppositely oriented sequences in a chromosome could allow inversion of the intervening material through homologous recombination. For example, the ribosomal RNA gene rrnD of Escherichia coli has the opposite orientation fro rrnB and rrnE and is separated from these genes by roughly 20% of the chromosome. Starting with a derivative of Cavalli Hfr, we have constructed mutants that have an inversion of the segment between rrnD and either rrnB or rrnE. These mutants are generally quite viable but do exhibit a slight reduction in growth rate relative to the parental strain. A major line of laboratory E. coli, W3110 and its derivatives, also has an inversion between rrnD and rrnE, probably created directly by a recombinational event between these highly homologous genes.",
"The tonB gene is required for the transport of several different iron-siderophore complexes across the Escherichia coli outer membrane. In this study, transcriptional regulation of the tonB gene was investigated by using three different tonB-lacZ fusions to monitor tonB expression under aerobic conditions and in the presence of a wild-type tonB gene. Prior work by other laboratories suggests that tonB is expressed at low constitutive levels regardless of changes in iron availability or the fur locus. In contrast, these data show that tonB transcription is repressed threefold by growth in the presence of FeCl3 compared with growth in the presence of the iron chelator dipyridyl and that this repression requires the fur locus. A 168-base-pair DNA fragment carrying the tonB promoter was sufficient for the observed transcriptional regulation. In addition, the tonB gene appeared to have a substantially stronger promoter than previously recognized. The inability of other laboratories to detect tonB transcription regulation appears to be due to the extremely slow growth of iron-starved tonB strains and the use of Mu d1(lac Apr)- or lambda plac Mu53-generated fusions that encode a thermolabile TrpA-LacZ hybrid protein. The data also suggest that the previously reported growth phase regulation of tonB occurs only in media with intermediate levels of available iron and is due to iron starvation-induced derepression as the culture approaches stationary phase.",
"The lac genes were inserted with phage Mu(Ap, lac) into the fhuA, fepA, cir and tonB genes which specify components of iron uptake systems. The expression of lac in all these operon fusions was controlled by the availability of iron to the cells, thereby facilitating a quick and simple measurement of the expression of the genes listed above. In an iron rich medium under anaerobic conditions all systems were strongly repressed. fhuA was depressed at higher iron concentration than was fepA or cir, and tonB was repressed only under anaerobic conditions and could be induced by iron limitation. Mutants constitutive for the expression of beta-galactosidase were selected in a fhuA-lac fusion strain. The outer membrane proteins Cir, FhuA, FecA, 76K and 83K were made constitutively in such mutant strains. Therefore, they were termed fur mutants. In these fur mutant strains, the synthesis of a 19K protein was reduced. Furthermore, it was found that transport of ferric enterochelin and ferrichrome was also constitutive in the fur mutant cells, and that ferric citrate uptake could be induced by only 10 microM citrate in the growth medium in contrast to wild-type cells in which at least 100 microM citrate was necessary. The fepA gene was concluded to be under an additional control, because it was not fully derepressed by the fur mutation.",
"The HindII and HindIII restriction maps of the attphi80-tonB-trp region of the Escherichia coli chromosome are presented. Analysis of phage DNAs carrying tonB mutations has allowed identification of a 1,730-base pair HindII fragment containing at least part of the tonB gene. This fragment is 4,020 base pairs from the end of trpA, with the total distance from attphi80 to trpA being 6,550 +/- 800 base pairs. Properties of hybrid plasmids containing insertions of various tonB+ restriction fragments suggest that tonB lies completely within the 1,730-base pair fragment. In addition, apparent fusions of beta-galactoside to proteins within the tonB region suggest that the entire region codes for more than one polypeptide."
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Directed DNA bending induced by retinoid X receptor complexes
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Retinoid X receptors (RXR) have been identified as common subunits in the regulation of multiple hormonal signaling pathways. Using circular permutation and phasing analysis of specific response elements, we present evidence that RXR-retinoic acid receptor and RXR-thyroid hormone receptor heterodimer or RXR-RXR homodimer complexes induce directed DNA bends when bound to their cognate response elements. The extent of DNA bending induced by the RXR alpha-containing complexes varied and depended on the structure of the DNA-binding sites and the RXR partners. The overall bending orientation for RXR-containing complexes is directed toward the major groove of the DNA helix at the center of hormone response elements. Our observation implicates DNA bending as a possible mechanism underlying transcriptional regulation of distinct retinoid and thyroid hormone responsive genes.
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[
"Can a transcriptional activator known to bend DNA be functionally replaced by a sequence-directed bend in Escherichia coli? To investigate this question, a partially truncated promoter was used, deleted of its -35 region and of its CRP binding site, leaving only two Pribnow boxes as functional elements. Synthetic and naturally occurring curved DNA sequences introduced upstream from these elements could restore transcription at either one of the two natural starts. Some of these hybrid promoters turned out to be more efficient than the CRP activated wild-type gal promoter in vivo. Control experiments performed with very similar sequences devoid of any curvature produced weak promoters only. Minimal changes in the location of the centre of curvature or perturbation in the amount of curvature strongly affected the level of expression. No significant stimulation of transcription could be detected in vitro. Furthermore, both gal P1 and P2 starts could be activated in vivo but also in vitro via a properly positioned CRP binding site. This partial analogy suggests that bending induced by the cAMP-CRP complex upon binding to its site may be biologically relevant to the mechanism of transcriptional activation.",
"Steroid hormone receptors control gene expression through binding, as dimers, to short palindromic response elements located upstream of the genes they regulate. An independent domain of approximately 70 amino acids directs this sequence-specific DNA binding and is highly conserved between different receptor proteins and related transcription factors. This domain contains two zinc-binding Cys2-Cys2 sequence motifs, which loosely resemble the 'zinc-finger' motifs of TFIIIA. Here we describe the structure of the DNA-binding domain from the oestrogen receptor, as determined by two-dimensional 1H NMR techniques. The two 'zinc-finger'-like motifs fold to form a single structural domain and are thus distinct from the independently folded units of the TFIIIA-type zinc fingers. The structure consists of two helices perpendicular to each other. A zinc ion, coordinated by four conserved cysteines, holds the base of a loop at the N terminus of each helix. This novel structural domain seems to be a general structure for protein-DNA recognition.",
"The basic nature of the sequence features that define a promoter sequence for Escherichia coli RNA polymerase have been established by a variety of biochemical and genetic methods. We have developed rigorous analytical methods for finding unknown patterns that occur imperfectly in a set of several sequences, and have used them to examine a set of bacterial promoters. The algorithm easily discovers the \"consensus\" sequences for the -10 and -35 regions, which are essentially identical to the results of previous analyses, but requires no prior assumptions about the common patterns. By explicitly specifying the nature of the search for consensus sequences, we give a rigorous definition to this concept that should be widely applicable. We also have provided estimates for the statistical significance of common patterns discovered in sets of sequences. In addition to providing a rigorous basis for defining known consensus regions, we have found additional features in these promoters that may have functional significance. These added features were located on either side of the -35 region. The pattern 5', or upstream, from the -35 region was found using the standard alphabet (A, G, C and T), but the pattern between the -10 and the -35 regions was detectable only in a sub-alphabet. Recent results relating DNA sequence to helix conformation suggest that the former (upstream) pattern may have a functional significance. Possible roles in promoter function are discussed in this light, and an observation of altered promoter function involving the upstream region is reported that appears to support the suggestion of function in at least one case.",
"The role of cyclic AMP in the modulation of gene expression in Escherichia coli is briefly reviewed. Recent results concerning the molecular mechanism by which cyclic AMP and its receptor protein activate transcription initiation are discussed.",
"Retinoic acid regulation of one member of the human class I alcohol dehydrogenase (ADH) gene family was demonstrated, suggesting that the retinol dehydrogenase function of ADH may play a regulatory role in the biosynthetic pathway for retinoic acid. Promoter activity of human ADH3, but not ADH1 or ADH2, was shown to be activated by retinoic acid in transient transfection assays of Hep3B human hepatoma cells. Deletion mapping experiments identified a region in the ADH3 promoter located between -328 and -272 bp which confers retinoic acid activation. This region was also demonstrated to confer retinoic acid responsiveness on the ADH1 and ADH2 genes in heterologous promoter fusions. Within a 34-bp stretch, the ADH3 retinoic acid response element (RARE) contains two TGACC motifs and one TGAAC motif, both of which exist in RAREs controlling other genes. A block mutation of the TGACC sequence located at -289 to -285 bp eliminated the retinoic acid response. As assayed by gel shift DNA binding studies, the RARE region (-328 to -272 bp) of ADH3 bound the human retinoic acid receptor beta (RAR beta) and was competed for by DNA containing a RARE present in the gene encoding RAR beta. Since ADH catalyzes the conversion of retinol to retinal, which can be further converted to retinoic acid by aldehyde dehydrogenase, these results suggest that retinoic acid activation of ADH3 constitutes a positive feedback loop regulating retinoic acid synthesis.",
"The control of gene transcription requires specific protein-protein and protein-DNA interactions. c-Myc, the protein product of the c-myc protooncogene, is a member of the basic helix-loop-helix leucine-zipper class of transcription factors. Although c-Myc is able to bind to a specific core hexanucleotide DNA sequence (CACGTG), its precise function in modulating transcription remains unclear. The recent discovery of Max, a basic helix-loop-helix leucine-zipper partner protein for c-Myc, suggests that the ability of c-Myc to regulate transcription is modulated by the presence of Max. By taking advantage of the altered mobility of protein-bound DNA in the mobility-shift assay, we demonstrate the homo- and heterodimeric complexes of c-Myc and Max are able to cause increased DNA flexure as measured by the circular permutation assay. Based on phasing analysis, c-Myc and Max homodimers bend DNA in opposite orientations, whereas c-Myc-Max heterodimers cause a smaller bend, in an orientation similar to that induced by Max homodimers. To address the possibility that the apparent opposite orientation of bending was the result of DNA unwinding by one of the proteins, we measured the ability of c-Myc and Max homodimers to affect DNA unwinding; we were unable to show any specific unwinding caused by c-Myc or Max. In addition to demonstrating that members of the basic helix-loop-helix leucine-zipper class of transcription factors are able to induce DNA bending, these results suggest that different transcription factor dimers are able to bind to identical DNA sequences and yet have distinct structural effects.",
"The bending locus of trypanosome kinetoplast DNA, identified by gel electrophoresis, has tracts of a simple repeat sequence (CA5-6 T) symmetrically distributed about it, with a repeat interval of 10 base pairs. The analogous bending induced when catabolite gene activating protein binds to its recognition sequence near the promoter of the Escherichia coli lac operon is centred on a site about 5-7 base pairs away from the centre of the protein binding site.",
"We have studied the rat malic enzyme gene as a model for thyroid hormone (triiodothyronine (T3)) regulation of transcription. Our previous studies showed that transcription of this gene is controlled by T3 in vivo. In this study, we used COS-7 cells in culture to determine the location of a T3 response element (TRE) within this gene. Cotransfection of the rat T3 alpha-receptor cDNA with a reporter gene linked to 5'-deletion mutants of the malic enzyme gene 5'-flanking region revealed the presence of a TRE between positions -315 and -248. Using T3 receptors synthesized in vitro from their cDNAs, we have identified, through the use of gel shift assays and footprinting, a single DNA-binding site (positions -281 to -261) for the receptor within the rat malic enzyme gene TRE. The site was capable of binding either the rat alpha- or human beta-receptor with similar affinities. Competition binding studies indicated that the apparent affinity of receptor binding to the malic enzyme gene was similar to that of the rat alpha-myosin heavy chain gene TRE (positions -151 to -122) and was significantly greater than that of the rat growth hormone TRE (positions -192 to -163). These results indicate that both the alpha- and beta-forms of the nuclear T3 receptor are capable of binding directly to the malic enzyme gene 5'-flanking region at a site which functions as a hormone-inducible cis-regulatory element. In conjunction with our previous finding that T3 induces or activates essential transcription factors which bind to the promoter, it appears that the regulation of transcription of the malic enzyme gene by thyroid hormone involves at least two regulatory pathways.",
"Yeast mitochondrial RNA polymerase can bind specifically to promoter-containing DNA fragments in vitro as detected by DNAse I or methidiumpropyl-EDTA. Fe(II) protection assays and gel retardation experiments. Retardation of RNA polymerase-DNA complexes was most pronounced when the promoter was located in the middle of a DNA fragment and was diminished when RNA polymerase was bound near one of the ends. This indicates that upon RNA polymerase-binding the DNA undergoes a conformational change which is most likely a bend. The degree of introduced bending correlated with the efficiency of transcription and promoter-binding in a series of promoter mutants, suggesting that bending is a functional event during promoter utilisation."
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Prelamin A cleavage in progeroid syndromes and lipodystrophies.
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Lamin A is a component of the nuclear lamina mutated in a group of human inherited disorders known as laminopathies. Among laminopathies, progeroid syndromes and lipodystrophies feature accumulation of prelamin A, the precursor protein which, in normal cells, undergoes a multi-step processing to yield mature lamin A. It is of utmost importance to characterize the prelamin A form accumulated in each laminopathy, since existing evidence shows that drugs acting on protein processing can improve some pathological aspects. We report that two antibodies raised against differently modified prelamin A peptides show a clear specificity to full-length prelamin A or carboxymethylated farnesylated prelamin A, respectively. Using these antibodies, we demonstrated that inhibition of the prelamin A endoprotease ZMPSTE24 mostly elicits accumulation of full-length prelamin A in its farnesylated form, while loss of the prelamin A cleavage site causes accumulation of carboxymethylated prelamin A in progeria cells. These results suggest a major role of ZMPSTE24 in the first prelamin A cleavage step.
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[
"HIV protease inhibitors (HIV-PIs) target the HIV aspartyl protease, which cleaves the HIV gag-pol polyprotein into shorter proteins required for the production of new virions. HIV-PIs are a cornerstone of treatment for HIV but have been associated with lipodystrophy and other side effects. In both human and mouse fibroblasts, we show that HIV-PIs caused an accumulation of prelamin A. The prelamin A in HIV-PI-treated fibroblasts migrated more rapidly than nonfarnesylated prelamin A, comigrating with the farnesylated form of prelamin A that accumulates in ZMPSTE24-deficient fibroblasts. The accumulation of farnesyl-prelamin A in response to HIV-PI treatment was exaggerated in fibroblasts heterozygous for Zmpste24 deficiency. HIV-PIs inhibited the endoproteolytic processing of a GFP-prelamin A fusion protein. The HIV-PIs did not affect the farnesylation of HDJ-2, nor did they inhibit protein farnesyltransferase in vitro. HIV-PIs also did not inhibit the activities of the isoprenyl-cysteine carboxyl methyltransferase ICMT or the prenylprotein endoprotease RCE1 in vitro, but they did inhibit ZMPSTE24 (IC(50): lopinavir, 18.4 +/- 4.6 microM; tipranavir, 1.2 +/- 0.4 microM). We conclude that the HIV-PIs inhibit ZMPSTE24, leading to an accumulation of farnesyl-prelamin A. The inhibition of ZMPSTE24 by HIV-PIs could play a role in the side effects of these drugs.",
"Protease inhibitors were a major therapeutic breakthrough in the mid-1990s for the treatment of HIV infection, which resulted in improved life expectancy for patients who had failed previous therapies. With time and evolution of the virus, however, there is a new population of patients with treatment-resistant disease and few treatment options. Darunavir is a synthetic nonpeptidic analogue of amprenavir with enhanced activity against resistant virus that became available in 2006. The purpose of this review was to describe the clinical pharmacology, pharmacokinetic and pharmacodynamic properties, and clinical efficacy of darunavir. Also discussed are the published clinical experience with darunavir, its adverse events, drug interactions, pharmacoeconomics, and dosing and administration. A MEDLINE and EMBASE search (English-language only) was performed from January 1996 through April 2007 using the key words darunavir and TMC114. Abstracts from relevant scientific meetings were searched for the years 2000 through 2007. Additionally, the US Food and Drug Administration Web site was accessed to review the new drug application summary and data presented therein. Darunavir was found to maintain antiretroviral activity against HIV with protease inhibitor mutations in 6 studies. Clinical efficacy and safety data are limited to 4 controlled and 2 uncontrolled trials. In 2 large Phase IIb clinical studies, viral suppression at 48 weeks to undetectable levels in heavily pretreated patients was achieved in 45% of patients compared with 10% of patients in the control group (P < 0.001). The addition of enfuvirtide enhanced this response rate to 58% compared with 11% of the patients who did not receive enfuvirtide (P < 0.001). Gastrointestinal symptoms, nausea, and headache were the most commonly reported events. Darunavir has improved activity against resistant HIV isolates in patients with few treatment choices, particularly when enfuvirtide is added. The safety profile of darunavir is comparable to other protease inhibitors based on early data.",
"The nuclear lamins form a karyoskeleton providing structural rigidity to the nucleus. One member of the lamin family, lamin A, is first synthesized as a 74 kDa precursor, prelamin A. After the endopeptidase and methylation reactions which occur after farnesylation of the CAAX-box cysteine, there is a second endoproteolysis that occurs 15 amino acids upstream from the C-terminal farnesylated cysteine residue. Studies with knockout mice have implicated the enzyme Zmpste24 (Face-1) as a suitable candidate to perform one or both of these proteolytic reactions. Evidence has been presented elsewhere establishing that Zmpste24 possesses a zinc-dependent CAAX endopeptidase activity. In the present study, we confirm this CAAX endopeptidase activity with recombinant, membrane-reconstituted Zmpste24 and show that it can accept a prelamin A farnesylated tetrapeptide as substrate. To monitor the second upstream endoproteolytic cleavage of prelamin A, we expressed a 33 kDa prelamin A C-terminal tail in insect cells. We demonstrate that this purified substrate possesses a C-terminal farnesylated and carboxyl-methylated cysteine and, therefore, constitutes a valid substrate for assaying the second endoproteolytic step in lamin A maturation. With this substrate, we demonstrate that insect cell membranes bearing recombinant Zmpste24 can also catalyse the second upstream endoproteolytic cleavage.",
"The involvement of the nuclear envelope in the modulation of chromatin organization is strongly suggested by the increasing number of human diseases due to mutations of nuclear envelope proteins. A common feature of these diseases, named laminopathies, is the occurrence of major chromatin defects. We previously reported that cells from laminopathic patients show an altered nuclear profile, and loss or detachment of heterochromatin from the nuclear envelope. Recent evidence indicates that processing of the lamin A precursor is altered in laminopathies featuring pre-mature aging and/or lipodystrophy phenotype. In these cases, pre-lamin A is accumulated in the nucleus and heterochromatin is severely disorganized. Here we report evidence indicating that pre-lamin A is mis-localized in the nuclei of Emery-Dreifuss muscular dystrophy fibroblasts, either bearing lamin A/C or emerin mutations. Abnormal pre-lamin A-containing structures are formed following treatment with a farnesyl-transferase inhibitor, a drug that causes accumulation of pre-lamin A. Pre-lamin A-labeled structures co-localize with heterochromatin clumps. These data indicate that in almost all laminopathies the expression of the mutant lamin A precursor disrupts the organization of heterochromatin domains. Our results further show that the absence of emerin expression alters the distribution of pre-lamin A and of heterochromatin areas, suggesting a major involvement of emerin in pre-lamin A-mediated mechanisms of chromatin remodeling.",
"HIV protease inhibitors (HIV-PIs) are key components of highly active antiretroviral therapy, but they have been associated with adverse side effects, including partial lipodystrophy and metabolic syndrome. We recently demonstrated that a commonly used HIV-PI, lopinavir, inhibits ZMPSTE24, thereby blocking lamin A biogenesis and leading to an accumulation of prelamin A. ZMPSTE24 deficiency in humans causes an accumulation of prelamin A and leads to lipodystrophy and other disease phenotypes. Thus, an accumulation of prelamin A in the setting of HIV-PIs represents a plausible mechanism for some drug side effects. Here we show, with metabolic labeling studies, that lopinavir leads to the accumulation of the farnesylated form of prelamin A. We also tested whether a new and chemically distinct HIV-PI, darunavir, inhibits ZMPSTE24. We found that darunavir does not inhibit the biochemical activity of ZMPSTE24, nor does it lead to an accumulation of farnesyl-prelamin A in cells. This property of darunavir is potentially attractive. However, all HIV-PIs, including darunavir, are generally administered with ritonavir, an HIV-PI that is used to block the metabolism of other HIV-PIs. Ritonavir, like lopinavir, inhibits ZMPSTE24 and leads to an accumulation of prelamin A.",
"Progerias are rare genetic diseases characterized by premature aging. Several progeroid disorders are caused by mutations that lead to the accumulation of a lipid-modified (farnesylated) form of prelamin A, a protein that contributes to the structural scaffolding for the cell nucleus. In progeria, the accumulation of farnesyl-prelamin A disrupts this scaffolding, leading to misshapen nuclei. Previous studies have shown that farnesyltransferase inhibitors (FTIs) reverse this cellular abnormality. We tested the efficacy of an FTI (ABT-100) in Zmpste24-deficient mice, a mouse model of progeria. The FTI-treated mice exhibited improved body weight, grip strength, bone integrity, and percent survival at 20 weeks of age. These results suggest that FTIs may have beneficial effects in humans with progeria."
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Prevalence of allergic diseases and atopy in childhood in Brod-Posavina County, Croatia
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A cross-sectional study was carried out in Brod-Posavina County, Croatia, to assess the prevalence of allergic diseases and atopy, as well as to investigate the possible etiologic factors for asthma, allergic rhinitis and eczema in childhood. The study included 1687 schoolchildren aged 10-11 years. Data were collected using standardized International Study of Asthma and Allergies in Childhood (ISAAC) Phase II written questionnaire. Skin prick tests were performed to provide an objective measure of atopy, defined as skin reactivity to one or more allergens. Lifetime prevalence of wheezing was 22.7%, rhinitis symptoms 22.5%, and eczema symptoms 17.9%. Period prevalence in the past 12 months was 7.9% for attacks of wheezing, 9.9% for rhinoconjunctivitis symptoms, and 10.1% for eczema symptoms. Of the children in which skin prick test was performed, 20.2% were positive for at least one of the allergens used, with house dust mite sensitization being the most frequent one. Risk factors for allergic disease include allergic disease in family, atopy, sensitization to indoor and outdoor allergens, and environmental tobacco smoke exposure at home. International comparison with the results of other ISAAC Phase II studies showed the Brod-Posavina County to be an area with moderate prevalence of atopy and current asthma symptoms.
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"BACKGROUND Asthma has emerged as an important public health problem of urban populations in Latin America. Epidemiological data suggest that a minority of asthma cases in Latin America may be associated with allergic sensitisation and that other mechanisms causing asthma have been overlooked. The aim of the present study was to investigate risk factors for atopic and non-atopic asthma in school-age children. METHODS A cross-sectional study was conducted among 3960 children aged 6-16 years living in Afro-Ecuadorian rural communities in Esmeraldas province in Ecuador. Allergic diseases and risk factors were assessed by questionnaire and allergic sensitisation by allergen skin prick reactivity. RESULTS A total of 390 (10.5%) children had wheeze within the previous 12 months, of whom 14.4% had at least one positive skin test. The population-attributable fraction for recent wheeze associated with atopy was 2.4%. Heavy Trichuris trichiura infections were strongly inversely associated with atopic wheeze. Non-atopic wheeze was positively associated with maternal allergic symptoms and sedentarism (watching television (>3 h/day)) but inversely associated with age and birth order. CONCLUSIONS The present study showed a predominance of non-atopic compared with atopic wheeze among schoolchildren living in a poor rural region of tropical Latin America. Distinct risk factors were associated with the two wheeze phenotypes and may indicate different causal mechanisms. Future preventive strategies in such populations may need to be targeted at the causes of non-atopic wheeze.",
"Certain foods may increase or decrease the risk of developing asthma, rhinoconjunctivitis and eczema. We explored the impact of the intake of types of food on these diseases in Phase Three of the International Study of Asthma and Allergies in Childhood. Written questionnaires on the symptom prevalence of asthma, rhinoconjunctivitis and eczema and types and frequency of food intake over the past 12 months were completed by 13-14-year-old adolescents and by the parents/guardians of 6-7-year-old children. Prevalence ORs were estimated using logistic regression, adjusting for confounders, and using a random (mixed) effects model. For adolescents and children, a potential protective effect on severe asthma was associated with consumption of fruit ≥3 times per week (OR 0.89, 95% CI 0.82 to 0.97; OR 0.86, 95% CI 0.76 to 0.97, respectively). An increased risk of severe asthma in adolescents and children was associated with the consumption of fast food ≥3 times per week (OR 1.39, 95% CI 1.30 to 1.49; OR 1.27, 95% CI 1.13 to 1.42, respectively), as well as an increased risk of severe rhinoconjunctivitis and severe eczema. Similar patterns for both ages were observed for regional analyses, and were consistent with gender and affluence categories and with current symptoms of all three conditions. If the association between fast foods and the symptom prevalence of asthma, rhinoconjunctivitis and eczema is causal, then the findings have major public health significance owing to the rising consumption of fast foods globally.",
"Asthma has emerged as an important public health problem in many Latin American countries over the past decade. In Brazil and Costa Rica, the prevalence of asthma and associated morbidity is as great or greater as reported in traditional high prevalence countries such as the US, but remains neglected as a public health priority. Asthma in Latin America is associated particularly with underprivileged populations living in cities but remains relatively rare in many rural populations. The causes of asthma in Latin America are likely to be associated with urbanization, migration, and the adoption of a modern 'Westernized' lifestyle and environmental changes that follow these processes that include changes in diet, physical activity, hygiene, and exposures to allergens, irritants, and outdoor and indoor pollutants. Because of the enormous social, genetic, and environmental contrasts within and between Latin American countries, and the large differences in prevalence associated with these differences, the investigation of asthma in Latin America provides important research opportunities to identify the social and biological mechanisms that underlie asthma development. Asthma in Latin America poses enormous challenges for health policy makers, health services, and researchers to respond to and alleviate the growing burden of asthma disability, particularly among marginalized urban populations.",
"The prevalence of allergic diseases is reported to have increased worldwide. Two questionnaire surveys, five years apart, were conducted to evaluate the trend of prevalence rates and possible risk factors among primary school children in Ankara, Turkey. A previous survey in 1992 revealed the lifetime prevalences of asthma, wheezing, allergic rhinitis and atopic dermatitis were 17.4%, 23.3%, 28% and 6.1%, and the prevalences for the last 12 months were 8.3%, 11.9%, 15.4% and 4%, respectively. The survey was repeated with the same questionnaire in the same age group (6-13 years) of the same school in May 1997. The parents of 358 boys and 380 girls completed the questionnaire. The lifetime and last 12 months' prevalences of asthma, wheezing, rhinitis and atopic dermatitis were 16.8%, 22.5%, 18.7%, 6.5%, and 9.8%, 13.3%, 14.1%, 4.3%, respectively. There was a significant change only for the lifetime prevalence of rhinitis (p < 0.001). The rate of indoor smoking had declined from 73.9% to 64%, and pet ownership had risen from 7.9% to 22.9% (p < 0.001 for both). Atopic family history was the most prominent risk factor for all types of allergic disorders. Male gender was a significant risk factor for current asthma and wheezing [odds ratio (OR) = 1.80 and 1.59; 95% confidence intervals (CI) = 1.09-2.98 and 1.01-2.48, respectively], and passive smoking affected the occurrence of allergic rhinitis (OR = 1.84; CI = 1.13-3.00). The prevalence rates of allergic diseases among primary school children in Ankara stabilized during a 5-year period for all diseases other than allergic rhinitis. However, there are changing behavior patterns, i.e. indoor smoking and keeping pet animals, which that may have affected these rates.",
"Studies conducted in transitional communities from Africa and Asia have pointed to the process of urbanisation as being responsible for the increase in asthma prevalence in developing regions. In Latin America, there are few published data available on the potential impact of urbanisation on asthma prevalence. The aim of the present study was to explore how the process of urbanisation may explain differences in asthma prevalence in transitional communities in north-eastern Ecuador. An ecological study was conducted in 59 communities in Esmeraldas Province, Ecuador. Indicators of urbanisation were grouped into three indices representing the processes associated with urbanisation: socioeconomic, lifestyle and urban infrastructure. Categorical principal components analysis was used to generate scores for each index and a fourth index--a summary urbanisation index--was derived from the most representative variables in each of the three indices. The authors analysed the associations between community asthma prevalence and the indices, as well as with each indicator variable of every group. The overall prevalence of asthma was 10.1% (range 0-31.4% between communities). Three of the four indices presented significant associations with community asthma prevalence: socioeconomic (r = 0.295, p = 0.023), lifestyle (r = 0.342, p = 0.008) and summary urbanisation index (r = 0.355, p = 0.006). Variables reflecting better socioeconomic status and a more urban lifestyle were associated with greater asthma prevalence. These data provide evidence that the prevalence of asthma increases with increasing levels of urbanisation in transitional communities, and factors associated with greater socioeconomic level and changes towards a more urban lifestyle may be particularly important.",
"The role of allergen exposure in the development of allergic disease has been a matter of considerable debate, and our understanding of the importance of allergens has evolved over the last 25 years. Several observational and primary prevention studies have investigated these relationships, and different studies reported inconsistent, and sometimes opposite findings. It has to be emphasized that a clear understanding of how aeroallergen exposure occurs, and accurate and reproducible measurement of exposure are essential prerequisites for understanding the role of exposure. However, our current understanding of how we get exposed to allergens is not based on solid evidence, but on a number of assumptions, and we urgently need to develop better proxy measures (or indices) of exposure. In addition, the relative importance of the timing of exposure (e.g. early compared to exposure in later life) is unknown. It is also unclear which route of exposure is the most relevant (e.g. inhaled vs. oral vs. transcutaneous). Available data suggest that the dose-response relationship between allergen exposure and allergic disease may differ between different allergens, dose ranges and exposure patterns, and these relationships may further differ between different populations and geographical areas. It is increasingly clear that childhood asthma and atopy are not single phenotypes, and it is likely that allergen exposure has different effect on distinct subgroups under the umbrella terms of 'sensitization' and 'asthma'. Susceptibility to allergen exposure, other environmental exposures and their interactions may also differ between individuals with different genetic predispositions. However, the precise nature of these complex relationships is unclear. We need a holistic approach offered by systems biology, with integration of information on the standardized and reliable measures of exposures (including allergens and other relevant exposures) with genetic and biological data to fully understand the role of allergens in the development of allergic disease.",
"There are large differences in the prevalence of atopic disease between urban and rural areas of developing countries, without good explanation. Diet has been associated with atopic disease, but studies of specific nutrients are contradictory, cross-sectional studies often being unsupported by trials. We investigated diet as an explanation for the difference in the prevalence of atopy between urban and rural areas in South Africa. A cross-sectional analysis of food frequency questionnaires and allergen skin tests from 698 children aged 8-13 years, recruited from 24 schools in Cape Province, South Africa, who were taking part in a case-control study of exercise-induced bronchospasm. Food frequency data were analysed with a principal components analysis (PCA). The first two principal components of diet explained 25% of the variance, and discriminated almost perfectly between urban and rural subjects. The 'urban' component of diet was strongly associated with positive skin tests even after adjusting for urban residence. There were no significant associations between individual foods or nutrients and positive skin tests, allowing for multiple testing. Diet explains part of the difference in prevalence between urban and rural areas. The ability to demonstrate this using PCA, but not by exhaustive analysis of all foods, reflects the value of reducing the number of dietary dimensions. The number of foods and nutrients which can be assessed, and the possibility of confounding and effect modification, make it difficult to identify the features of diet most directly implicated in disease. This may explain inconsistencies in dietary studies."
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Sucrose nonfermenting AMP-activated protein kinase-related kinase is phosphorylated on Thr
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The signaling mechanisms mediating myocardial glucose transport are not fully understood. Sucrose nonfermenting AMP-activated protein kinase (AMPK)-related kinase (SNARK) is an AMPK-related protein kinase that is expressed in the heart and has been implicated in contraction-stimulated glucose transport in mouse skeletal muscle. We first determined if SNARK is phosphorylated on Thr
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[
"AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme that is expressed in most mammalian tissues including cardiac muscle. Among the multiple biological processes influenced by AMPK, regulation of fuel supply and energy-generating pathways in response to the metabolic needs of the organism is fundamental and likely accounts for the remarkable evolutionary conservation of this enzyme complex. By regulating the activity of acetyl-coenzyme A carboxylase, AMPK affects levels of malonyl-coenzyme A, a key energy regulator in the cell. AMPK is generally quiescent under normal conditions but is activated in response to hormonal signals and stresses sufficient to produce an increase in AMP/ATP ratio, such as hypoglycemia, strenuous exercise, anoxia, and ischemia. Once active, muscle AMPK enhances uptake and oxidative metabolism of fatty acids as well as increases glucose transport and glycolysis. Data from AMPK deficiency models suggest that AMPK activity might influence the pathophysiology and therapy of diabetes and increase heart tolerance to ischemia. Effects that are not as well understood include AMPK regulation of transcription. Different AMPK isoforms are found in distinct locations within the cell and have distinct functions in different tissues. A principal mode of AMPK activation is phosphorylation by upstream kinases (eg, LKB1). These kinases have a fundamental role in cell-cycle regulation and protein synthesis, suggesting involvement in a number of human disorders including cardiac hypertrophy, apoptosis, cancer, and atherosclerosis. The physiological role played by AMPK during health and disease is far from being clearly defined. Naturally occurring mutations affecting the nucleotide-sensing modules in the regulatory gamma subunit of AMPK lead to enzyme dysregulation and inappropriate activation under resting conditions. Glycogen accumulation ensues, leading to human disease manifesting as cardiac hypertrophy, accessory atrioventricular connections, and degeneration of the physiological conduction system. Whether AMPK is a key participant or bystander in other disease states and whether its selective manipulation may significantly benefit these conditions remain important questions.",
"The effect of statins on hepatic histology in non-alcoholic fatty liver disease (NAFLD) is not known. This study explores hepatic histology in NAFLD patients before and after initiation of statin therapy and compares histological outcome with NAFLD patients who had not been prescribed statins. Sixty-eight NAFLD patients were re-evaluated. Follow-up ranged from 10.3 to 16.3 years. Subjects were clinically investigated and a repeat liver biopsy was obtained. No patient was taking statins at baseline while 17 patients were treated with statins at follow-up. At baseline, patients that later were prescribed statins had significantly higher BMI and more pronounced hepatic steatosis. At follow-up patients on medication with statins continued to have significantly higher BMI. Diabetes was significantly more common among patients on medication with statins and they had significantly more pronounced insulin resistance. However, they exhibited a significant reduction of liver steatosis at follow-up as opposed to patients not taking statins. Despite exhibiting a high risk profile for progression of liver fibrosis, only four patients on statin treatment progressed in fibrosis stage. Statins can be prescribed in patients with elevated liver enzymes because of NAFLD.",
"Hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide. The biological and therapeutic importance of host cellular cofactors for viral replication has been recently appreciated. Here we examined the roles of SNF1/AMP kinase-related kinase (SNARK) in HCV replication and pathogenesis. The JFH1 infection system and the full-length HCV replicon OR6 cell line were used. Gene expression was knocked down by siRNAs. SNARK mutants were created by site-directed mutagenesis. Intracellular mRNA levels were measured by qRT-PCR. Endogenous and overexpressed proteins were detected by Western blot analysis and immunofluorescence. Transforming growth factor (TGF)-β signaling was monitored by a luciferase reporter construct. Liver biopsy samples from HCV-infected patients were analyzed for SNARK expression. Knockdown of SNARK impaired viral replication, which was rescued by wild type SNARK but not by unphosphorylated or kinase-deficient mutants. Knockdown and overexpression studies demonstrated that SNARK promoted TGF-β signaling in a manner dependent on both its phosphorylation and kinase activity. In turn, chronic HCV replication upregulated the expression of SNARK in patients. Further, the SNARK kinase inhibitor metformin suppressed both HCV replication and SNARK-mediated enhancement of TGF-β signaling. Thus reciprocal regulation between HCV and SNARK promotes TGF-β signaling, a major driver of hepatic fibrogenesis. These findings suggest that SNARK will be an attractive target for the design of novel host-directed antiviral and antifibrotic drugs.",
"The mechanisms of the improvement of glucose homeostasis through angiotensin receptor blockers are not fully elucidated in hypertensive patients. We investigated the effects of telmisartan on insulin signaling and glucose uptake in cultured myotubes and skeletal muscle from wild-type and muscle-specific peroxisome proliferator-activated receptor (PPAR) δ knockout (MCK-PPARδ(-/-)) mice. Telmisartan increased PPARδ expression and activated PPARδ transcriptional activity in cultured C2C12 myotubes. In palmitate-induced insulin-resistant C2C12 myotubes, telmisartan enhanced insulin-stimulated Akt and Akt substrate of 160 kDa (AS160) phosphorylation as well as Glut4 translocation to the plasma membrane. These effects were inhibited by antagonizing PPARδ or phosphatidylinositol-3 kinase, but not by PPARγ and PPARα inhibition. Palmitate reducing the insulin-stimulated glucose uptake in C2C12 myotubes could be restored by telmisartan. In vivo experiments showed that telmisartan treatment reversed high-fat diet-induced insulin resistance and glucose intolerance in wild-type mice but not in MCK-PPARδ(-/-) mice. The protein levels of PPARδ, phospho-Akt, phospho-AS160, and Glut4 translocation to the plasma membrane in the skeletal muscle on insulin stimulation were reduced by high-fat diet and were restored by telmisartan administration in wild-type mice. These effects were absent in MCK-PPARδ(-/-) mice. These findings implicate PPARδ as a potential therapeutic target in the treatment of hypertensive subjects with insulin resistance.",
"Although most hepatitis C virus (HCV) infections are acquired by injection drug use, prospective data on the progression of liver fibrosis are sparse. Baseline liver biopsies were obtained (1996-1998) on a random sample of 210 out of 1667 HCV-positive injection drug users (IDUs). Subjects were followed biannually, with a second biopsy offered to those eligible. Paired biopsies were scored 0 to 6 (modified Ishak score), significant fibrosis was defined as score 3 or greater, and progression of fibrosis was defined as an increase 2 or more units or clinical evidence of end-stage liver disease. Predictive values of blood markers [FibroSURE, aspartate aminotransferase-to-platelet-ratio index (APRI) and alanine aminotransferase (ALT)] were assessed for detection of contemporaneous and future liver fibrosis. Among 119 prospectively followed IDUs, 96% were African American; 97% HCV genotype 1a/b; 27% HIV-infected, and median age was 42 years. Most (90.7%) did not have significant liver fibrosis at first biopsy. Although predictive value for detecting insignificant fibrosis at first biopsy was greater than 95% for FibroSURE, APRI, and ALT, specificities were 88.9%, 72.7%, and 72.7%, respectively. After 4.2 years median follow-up, 21% had progression of fibrosis, which was significantly associated with serum level of HCV RNA and ALT. No serological test had predictive value greater than 40% for contemporaneous or future significant fibrosis. Even initial biopsy result had only a 30.4% value for predicting future significant fibrosis. In conclusion, significant liver fibrosis and progression were detected in some, but not most, IDUs in this cohort. In this setting with low fibrosis prevalence, FibroSURE, ALT, and APRI tests predict insignificant fibrosis; however, further work is needed to find noninvasive markers of significant liver fibrosis.",
"The present study was performed to investigate the involvement of SNARK in physical activity levels in mice. To examine the acute effect of SNARK deficiency on voluntary running, Snark-deficient mice (Snark(+/-): n = 16) and their wild-type counterparts (Snark(+/+): n = 16) were assigned to sedentary or exercise (1 wk voluntary wheel running) groups. In addition, to clarify the differences in voluntary running activity and its effect between genotypes, mice (Snark(+/+): n = 16; Snark(+/-): n = 16) were also kept in individual cages with/without a running wheel for 5 mo. Unexpectedly, in both voluntary running experiments, running distances were increased in Snark(+/-) mice compared with Snark(+/+) mice. Under sedentary conditions, body and white adipose tissue weights were increased significantly in Snark(+/-) mice. However, no significant differences were observed between the two genotypes under exercise conditions, and the values were significantly less than those under sedentary conditions in the long-term experiment. In the short-term experiment, serum interleukin-6 level in exercised Snark(+/+) mice was the same as that in sedentary Snark(+/+) mice, whereas that in sedentary Snark(+/-) mice was significantly lower than in the other groups. In contrast, serum leptin level was reduced significantly in exercised Snark(+/-) mice compared with sedentary Snark(+/-) mice. The results of this study demonstrated that exposure to an environment that allows voluntary exercise promotes increased running activity and prevents obesity in Snark-deficient mice.",
"Although proteins phosphorylated on tyrosine residues can be enriched by immunoprecipitation with anti-phosphotyrosine antibodies, it has been difficult to identify proteins that are phosphorylated on serine/threonine residues because of lack of immunoprecipitating antibodies. In this report, we describe several antibodies that recognize phosphoserine/phosphothreonine-containing proteins by Western blotting. Importantly, these antibodies can be used to enrich for proteins phosphorylated on serine/threonine residues by immunoprecipitation, as well. Using these antibodies, we have immunoprecipitated proteins from untreated cells or those treated with calyculin A, a serine/threonine phosphatase inhibitor. Mass spectrometry-based analysis of bands from one-dimensional gels that were specifically observed in calyculin A-treated samples resulted in identification of several known serine/threonine-phosphorylated proteins including drebrin 1, alpha-actinin 4, and filamin-1. We also identified a protein, poly(A)-binding protein 2, which was previously not known to be phosphorylated, in addition to a novel protein without any obvious domains that we designate as Frigg. Frigg is widely expressed and was demonstrated to be a protein kinase A substrate in vitro. We identified several in vivo phosphorylation sites by tandem mass spectrometry using Frigg protein immunoprecipitated from cells. Our method should be applicable as a generic strategy for enrichment and identification of serine/threonine-phosphorylated substrates in signal transduction pathways."
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Surgical outcome and recurrence-free survival among breast cancer patients in Johor, Malaysia
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Objective: To gauge surgical outcome in breast cancer patients with particular reference to overall survival and
recurrence free survival among breast cancer patients in Hospital Sultanah Nora Ismail Batu Pahat, Johor, Malaysia.
Methods: Patients undergoing ablative breast cancer surgery were identified and clinical records were assessed.
Inclusion criteria for enrolment were stage I-IV breast malignancy necessitating resection with or without radiotherapy/
chemotherapy from 2007 to 2013. All individuals had a pre-operative assessment. The post operative assessment period
ranged from 1 year to 5 years. Survival distributions were analyzed using Kaplan-Meier curves. Results: A total of
121 patients were included in this study, with an age range of 28-78 years. Some 98% had undergone local excision/
lumpectomy/ mastectomy with axillary clearance. While 81% of patients underwent chemotherapy, only 69% had
radiotherapy. Tumours were oestrogen receptor positive in 58% of cases and progesterone receptor positive in 62%.
Local recurrence was detected in 10%. The mean age at diagnosis was 51.3 + 10.4 years. The overall survival analysis
was based on 22 deaths among the 121 patients (18.2%). Three-year and five-year survival rates were 87.6% and 78.4%,
respectively. Analysis of recurrence-free-survival (RFS) was based on 12 events among 121 patients. The Kaplan-Meier
RFS analysis revealed that in 90% of the patients with recurrence, it occurred within 45 months. The five year RFS
rate was 84.5%. The median time taken from diagnosis to ablative surgery was 51 days (upper limit of 791 days).
Only distant metastasis was a significant factor that impacted on both overall survival and recurrence-free survival
(p<0.001). Conclusion: Overall survival among our breast cancer patients in our facility is comparable to other in
other tertiary centres in the country. A trend for earlier detection was noted.
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[
"Several international studies have found that survival from breast cancer is lower in the United Kingdom than in some other European countries. We have compared breast cancer survival between the national populations of England, Norway and Sweden, with a view to identifying subsets of patients with particularly good or adverse survival outcomes. We extracted cases of breast cancer in women diagnosed 1996-2004 from the national cancer registries of the 3 countries. The study comprised 303,657 English cases, 24,919 Norwegian cases and 57,512 cases from Sweden. Follow-up was in 2001-2004. The main outcome measures were 5-year cumulative relative survival and excess death rates, stratified by age and period of follow-up. In comparison with Norway and Sweden, the excess mortality in England was particularly pronounced in the first month and in the first year after diagnosis, and generally more marked in the oldest age groups. Compared with Norwegian patients, 81% of the excess deaths in the English patients occurred in the first 2 years after diagnosis. Our findings emphasise the importance of awareness of symptoms and early detection as the main strategy to improve breast cancer survival in the United Kingdom.",
"Two hospital-based breast cancer databases (University Malaya Medical Center, Malaysia [n = 1513] and National University Hospital, Singapore [n = 2545]) were merged into a regional registry of breast cancer patients diagnosed between 1990 and 2007. A review of the data found 51% of patients diagnosed before the age of 50 years. and 72% percent of the women were Chinese followed by Malays (16%), Indians (8%), and other races (4%). Median tumor size at presentation was 26 mm and about 25% of patients presented with TNM stage III or IV disease. Most tumors were of ductal histology (87%). Fifty-seven percent of tumors were estrogen receptor positive and 40% were poorly differentiated. Of those patients who had surgery, 70% had mastectomy while 30% had breast conserving surgery. Overall, chemotherapy was administered to 56% of patients and hormonal treatment to 60%. Five-year overall survival was 82.5% in patients with TNM stage 0 to stage II cancer, and 30.2% in those with later stages.",
"The rapid growth of corporate investment in the Malaysian private hospital sector has had a considerable impact on the health care system. Sustained economic growth, the development of new urban areas, an enlarged middle class, and the inclusion of hospital insurance in salary packages have all contributed to a financially lucrative investment environment for hospital entrepreneurs. Many of Malaysia's most technologically advanced hospitals employing leading specialists are owned and operated as corporate business ventures. Corporate hospital investment has been actively encouraged by the government, which regards an expanded private sector as a vital complement to the public hospital system. Yet this rapid growth of corporately owned private hospitals has posed serious contradictions for health care policy in terms of issues such as equity, cost and quality, the effect on the wider health system, and the very role of the state in health care provision. This article describes the growth of corporate investment in Malaysia's private hospital sector and explores some of the attendant policy contradictions.",
"There are large differences in socio-economic growth within the region of South East Asia, leading to sharp contrasts in health-systems development between countries. This study compares breast cancer presentation and outcome between patients from a high income country (Singapore) and a middle income country (Malaysia) in South East Asia. Within the Singapore Malaysia Breast Cancer Registry we identified all consecutive patients diagnosed with breast cancer between 1993 and 2007 at the National University Hospital in Singapore (high income country, n=2,141) and the University of Malaya Medical Center in Kuala Lumpur, Malaysia (middle income country, n=3,320). We compared demographics, tumor characteristics, treatment patterns, and survival between patients from both countries. In Malaysia, patients were less often diagnosed with in situ breast cancer (adjusted odds ratio [ORadj] 0.2; 95% confidence interval [95% CI] 0.1-0.3), more likely to be diagnosed with late stage (III and IV) disease (ORadj for stage III 1.6; 95% CI 1.3-2.0; ORadj for stage IV 1.2; 95% CI 1.1-1.4) as compared to patients from Singapore. Univariate analysis showed that Malaysian patients were at a 72% increased risk of death as compared to Singaporeans. After adjusting for other prognostic factors, the risk decreased by only 5% (ORadj 1.67, 95% CI 1.44-1.92). Differences in way of presentation (except stage and tumor size) and treatment of breast cancer patients from the two countries are small. The overall survival of breast cancer patients from Malaysia is much lower than that of Singaporean patients.",
"Breast cancer is the commonest cancer in most countries in Asia. The incidence rates remain low, although increasing at a more rapid rate than in western countries, due to changes in the lifestyle and diet. There are many differences between breast cancer in Asia compared with western countries. The mean age at onset is younger than in the west, and unlike the west, the age-specific incidence decreases after the age of 50 years. Because there is no population-based breast cancer screening program in the majority of Asian countries, the majority of patients present with advanced disease. There is a higher proportion of hormone receptor-negative patients, and some evidence that the cancers in Asia are of a higher grade. Most of the Asian countries are low- and middle-income countries, where access to effective care is limited. Because of the late detection and inadequate access to care, survival of women with breast cancer in Asia is lower than in western countries. Improving breast health in most of the Asian countries remains a challenge that may be overcome with collaboration from multiple sectors, both public and private."
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Polo-like kinase 4 phosphorylates Asterless/A and regulates centriole assembly.
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Centriole assembly initiates when Polo-like kinase 4 (Plk4) interacts with a centriole "targeting-factor." In Drosophila, Asterless/Asl (Cep152 in humans) fulfills the targeting role. Interestingly, Asl also regulates Plk4 levels. The N-terminus of Asl (Asl-A; amino acids 1-374) binds Plk4 and promotes Plk4 self-destruction, although it is unclear how this is achieved. Moreover, Plk4 phosphorylates the Cep152 N-terminus, but the functional consequence is unknown. Here, we show that Plk4 phosphorylates Asl and mapped 13 phospho-residues in Asl-A. Nonphosphorylatable alanine (13A) and phosphomimetic (13PM) mutants did not alter Asl function, presumably because of the dominant role of the Asl C-terminus in Plk4 stabilization and centriolar targeting. To address how Asl-A phosphorylation specifically affects Plk4 regulation, we generated Asl-A fragment phospho-mutants and expressed them in cultured Drosophila cells. Asl-A-13A stimulated kinase activity by relieving Plk4 autoinhibition. In contrast, Asl-A-13PM inhibited Plk4 activity by a novel mechanism involving autophosphorylation of Plk4's kinase domain. Thus, Asl-A's phosphorylation state determines which of Asl-A's two opposing effects are exerted on Plk4. Initially, nonphosphorylated Asl binds Plk4 and stimulates its kinase activity, but after Asl is phosphorylated, a negative-feedback mechanism suppresses Plk4 activity. This dual regulatory effect by Asl-A may limit Plk4 to bursts of activity that modulate centriole duplication.
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[
"The human Polo-like kinase 1 (PLK1) and its functional homologues that are present in other eukaryotes have multiple, crucial roles in meiotic and mitotic cell division. By contrast, the functions of other mammalian Polo family members remain largely unknown. Plk4 is the most structurally divergent Polo family member; it is maximally expressed in actively dividing tissues and is essential for mouse embryonic development. Here, we identify Plk4 as a key regulator of centriole duplication. Both gain- and loss-of-function experiments demonstrate that Plk4 is required--in cooperation with Cdk2, CP110 and Hs-SAS6--for the precise reproduction of centrosomes during the cell cycle. These findings provide an attractive explanation for the crucial function of Plk4 in cell proliferation and have implications for the role of Polo kinases in tumorigenesis.",
"Centrioles are microtubule-based structures that organize the centrosome and nucleate cilia. Centrioles duplicate once per cell cycle, and duplication requires Plk4, a member of the Polo-like kinase family; however, the mechanism linking Plk4 activity and centriole formation is unknown. In this study, we show in human and frog cells that Plk4 interacts with the centrosome protein Cep152, the orthologue of Drosophila melanogaster Asterless. The interaction requires the N-terminal 217 residues of Cep152 and the crypto Polo-box of Plk4. Cep152 and Plk4 colocalize at the centriole throughout the cell cycle. Overexpression of Cep152 (1-217) mislocalizes Plk4, but both Cep152 and Plk4 are able to localize to the centriole independently of the other. Depletion of Cep152 prevents both normal centriole duplication and Plk4-induced centriole amplification and results in a failure to localize Sas6 to the centriole, an early step in duplication. Cep152 can be phosphorylated by Plk4 in vitro, suggesting that Cep152 acts with Plk4 to initiate centriole formation.",
"Centrosome amplification is a common feature of many cancer cells, and it has been previously proposed that centrosome amplification can drive genetic instability and so tumorigenesis. To test this hypothesis, we generated Drosophila lines that have extra centrosomes in approximately 60% of their somatic cells. Many cells with extra centrosomes initially form multipolar spindles, but these spindles ultimately become bipolar. This requires a delay in mitosis that is mediated by the spindle assembly checkpoint (SAC). As a result of this delay, there is no dramatic increase in genetic instability in flies with extra centrosomes, and these flies maintain a stable diploid genome over many generations. The asymmetric division of the larval neural stem cells, however, is compromised in the presence of extra centrosomes, and larval brain cells with extra centrosomes can generate metastatic tumors when transplanted into the abdomens of wild-type hosts. Thus, centrosome amplification can initiate tumorigenesis in flies.",
"Centrosome amplification is a common feature of human tumors, but whether this is a cause or a consequence of cancer remains unclear. Here, we test the consequence of centrosome amplification by creating mice in which centrosome number can be chronically increased in the absence of additional genetic defects. We show that increasing centrosome number elevated tumor initiation in a mouse model of intestinal neoplasia. Most importantly, we demonstrate that supernumerary centrosomes are sufficient to drive aneuploidy and the development of spontaneous tumors in multiple tissues. Tumors arising from centrosome amplification exhibit frequent mitotic errors and possess complex karyotypes, recapitulating a common feature of human cancer. Together, our data support a direct causal relationship among centrosome amplification, genomic instability, and tumor development.",
"Both gain and loss of function studies have identified the Polo-like kinase Plk4/Sak as a crucial regulator of centriole biogenesis, but the mechanisms governing centrosome duplication are incompletely understood. In this study, we show that the pericentriolar material protein, Cep152, interacts with the distinctive cryptic Polo-box of Plk4 via its N-terminal domain and is required for Plk4-induced centriole overduplication. Reduction of endogenous Cep152 levels results in a failure in centriole duplication, loss of centrioles, and formation of monopolar mitotic spindles. Interfering with Cep152 function prevents recruitment of Plk4 to the centrosome and promotes loss of CPAP, a protein required for the control of centriole length in Plk4-regulated centriole biogenesis. Our results suggest that Cep152 recruits Plk4 and CPAP to the centrosome to ensure a faithful centrosome duplication process.",
"The number of centrioles is tightly controlled to ensure bipolar spindle assembly, which is a prerequisite to maintain genome integrity. However, our understanding of the fundamental principle that governs the formation of a single procentriole per parental centriole is incomplete. Here, we show that the local restriction of Plk4, a master regulator of the procentriole formation, is achieved by a bimodal interaction of STIL with Plk4. We demonstrate that the conserved short coiled-coil region of STIL binds to and protects Plk4 from protein degradation at the site of procentriole formation. On the other hand, the conserved C-terminal region of STIL named truncated in microcephaly (TIM) domain promotes autophosphorylation and degradation of adjacent Plk4 by the direct interaction. Thus, we propose that positive and negative regulation based on the bimodal binding of Plk4 and STIL ensures the formation of a single procentriole per parental centriole.",
"Centrosomes, the major organizers of the microtubule network in most animal cells, are composed of centrioles embedded in a web of pericentriolar material (PCM). Recruitment and stabilization of PCM on the centrosome is a centriole-dependent function. Compared to the considerable number of PCM proteins known, the molecular characterization of centrioles is still very limited. Only a few centriolar proteins have been identified so far in Drosophila, most related to centriole duplication. We have cloned asterless (asl) and found that it encodes a 120 kD highly coiled-coil protein that is a constitutive pancentriolar and basal body component. Loss of asl function impedes the stabilization/maintenance of PCM at the centrosome. In embryos deficient for Asl, development is arrested right after fertilization. Asl shares significant homology with Cep 152, a protein described as a component of the human centrosome for which no functional data is yet available. The cloning of asl offers new insight into the molecular composition of Drosophila centrioles and a possible model for the role of its human homolog. In addition, the phenotype of asl-deficient flies reveals that a functional centrosome is required for Drosophila embryo development."
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Dynamic formation of multicellular aggregate in ovarian cancer SKOV3 and OVCAR-3 cells and integrin expression
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Objective: To investigate the regulatory role of fibronectin (FN) in the formation of multicellular aggregate (MCA)
in ovarian cancer SKOV3 and OVCAR-3 cells and integrin expression. Methods: The dynamic formation of MCA in
SKOV3 and OVCAR-3 was determined using the liquid overlay technique in the presence or absence of FN, anti-FN,
RGD peptide, control RGE. The expression of α3β1, α4β1 and α5β1 integrin in monolayer cells, MCA and FN-treated
MCA were determined by flow cytometry and quantitative RT-PCR. Results: OVCAR-3 and SKOV3 MCA were formed
on the 4th and 8th day and peaked on the 6th and 9th day, respectively. Treatment with different concentrations of FN,
LN, type IV collagen and control RGE peptide promoted MCA growth, which was mitigated by anti-FN and RGD
peptide. In comparison with monolayer cells, up-regulated α3β1, α4β1 and α5β1 expression were detected in MCA
while treatment with FN in both cells. Conclusions: OVCAR-3 and SKOV3 cells had varying dynamic formation of
MCA in our experimental system. FN enhanced MCA formation in both cells, which was associated with increased
expression of 3β1, α4β1 and α5β1 in the MCA. Therefore, FN and these integrins may be new therapeutic targets for
intervention of ovarian cancer metastasis.
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[
"Tumor spheroids were cultured from five human glioma cell lines which differed considerably in their relative amount and composition of glycosaminoglycans (GAG), fibronectin and other extracellular matrix (ECM) components when grown as monolayer cultures. These differences were also evident when the cells were grown as spheroids. Under the 3-dimensional geometry of the spheroid system, there was, however, generally a more extensive ECM. Especially noteworthy was the presence of a small proteoglycan, probably a dermatan sulphate proteoglycan, in the ECM of the spheroids, but not in the monolayers. Noteworthy was also the appearance of fibronectin in spheroids which did not show any staining for fibronectin when grown as monolayer. The two spheroid types (U-87MG, U-105MG) with the most extensive matrix, and with the lowest proportion of hyaluronic acid (HA), had a low proliferation rate, whereas the three other spheroid types (U-118MG, U-138MG, U-251MG) with a less extensive ECM, and a relatively high production of HA had a much higher proliferation rate. These data provide further evidence for the usefulness of culturing cell lines as spheroids in the process of understanding important cell biological phenomena.",
"Ovarian cancer, in particular epithelial ovarian cancer (EOC), is commonly diagnosed when the tumor has metastasized into the abdominal cavity with an accumulation of ascites fluid. Combining histopathology and genetic variations, EOC can be sub-grouped into Type-I and Type-II tumors, of which the latter are more aggressive and metastatic. Metastasis and chemoresistance are the key events associated with the tumor microenvironment that lead to a poor patient outcome. Kallikrein-related peptidases (KLKs) are aberrantly expressed in EOC, in particular, in the more metastatic Type-II tumors. KLKs are a family of 15 serine proteases that are expressed in diverse human tissues and involved in various patho-physiological processes. As extracellular enzymes, KLKs function in the hydrolysis of growth factors, proteases, cell membrane bound receptors, adhesion proteins, and cytokines initiating intracellular signaling pathways and their downstream events. High KLK levels are differentially associated with the prognosis of ovarian cancer patients, suggesting that they not only have application as biomarkers but also function in disease progression, and therefore are potential therapeutic targets. Recent studies have demonstrated the function of these proteases in promoting and/or suppressing the invasive behavior of ovarian cancer cells in metastasis in vitro and in vivo. Both conventional cell culture methods and three-dimensional platforms have been applied to mimic the ovarian cancer microenvironment of patients, such as the solid stromal matrix and ascites fluid. Here we summarize published studies to provide an overview of our understanding of the role of KLKs in EOC, and to lay the foundation for future research directions.",
"A431 cells grown as three-dimensional spheroids show growth stimulation in response to nanomolar concentrations of EGF in contrast to monolayer cultures that show inhibition. In investigating the alterations in EGF signal transduction that underlie this modification of the proliferative response, we have compared the expression of EGF receptors on A431 cells under these conditions and related our findings to tyrosine phosphorylation and the growth response. EGF receptors were measured by 125I-EGF binding to trypsin-dispersed cells. Unexpectedly, dispersion of the monolayers caused an 80% decrease in surface EGF receptor, although, after dispersion, EGF receptor was digested by trypsin with a half-life of 69 +/- 32 min. No evidence for a comparable loss of cellular EGF receptor was seen on trypsin dispersion of spheroids. After allowing for this effect, we found that the receptor density on nondispersed monolayers (5 x 10(6) per cell) was twentyfold greater than that on spheroids (0.25 x 10(6) per cell). EGF-induced tyrosine phosphorylation was confined to the outermost cells of the spheroid, although the presence of surface-expressed EGF binding sites could be demonstrated throughout the structure and the number of EGF receptors/cell on dispersed spheroid cells showed a single distribution peak by flow cytometry, with no evidence for more than one population. Using RCM-lysozyme as a substrate, tyrosine phosphatase activity in spheroids lay within the range observed in monolayer cultures. Autophosphorylation of the EGF receptor following EGF stimulation in monolayer cultures of A431 cells rose rapidly in the first 10 seconds and then slowly increased for at least 3 h. In spheroids, it reached a maximum within 10 seconds and then declined over 3 h. Since the microenvironment within a tumor resembles that in a spheroid, a similar reduction in surface EGF receptor expression may be expected in tumors relative to monolayer cultures, together with corresponding growth stimulation in response to EGF.",
"The integrins are a family of cell surface receptors which mediate cellular adhesion and signalling events. Our goal was to evaluate integrin function and signalling pathways in ovarian cancer cells. Ovarian cancer cell lines, NIH:OVCAR-3 and NIH:OVCAR-5, exhibited distinct extracellular matrix (ECM) binding preferences which were mediated primarily through beta1 integrin interactions. Western blot analysis was used to identify changes in cellular phosphotyrosine, focal adhesion kinase (FAK) and mitogen activated protein (MAP) kinase. Tyrosine phosphorylation of integrin-associated phosphoproteins was not enhanced in either cell type in response to adhesion onto ECM components or receptor crosslinking. FAK expression was greater in NIH:OVCAR-5 cells while MAP kinase activity was higher in NIH:OVCAR-3 cells. The data suggest that these two ovarian cancer cell lines exhibit specific ECM binding preferences and distinct differences in phosphotyrosine, focal adhesion and MAP kinase expression profiles.",
"Ovarian carcinoma multicellular spheroids are an in vitro model of micrometastasis whose adhesive abilities have not been elucidated. In this study, we identified adhesion molecules that mediate the formation of ovarian carcinoma spheroids and their subsequent adhesion to extracellular matrix proteins. The NIH:OVCAR5, but not the SKOV3, ovarian carcinoma cell line formed spheroids similar to multicellular aggregates isolated from patient ascitic fluid. NIH:OVCAR5 spheroid formation was augmented by a beta 1-integrin-stimulating monoclonal antibody or exogenous fibronectin, but was inhibited by blocking monoclonal antibodies against the alpha 5- or beta 1-integrin subunits. By immunohistochemical staining, alpha 2-, alpha 3-, alpha 5-, alpha 6-, and beta 1-integrin subunits, CD44, and fibronectin were detected in NIH:OVCAR5 spheroids. NIH:OVCAR5 spheroids adhered to fibronectin, laminin, and type IV collagen, and this adhesion was partially inhibited by blocking antibodies against the alpha 5-, alpha 6-, and alpha 2-integrin subunits, respectively. A blocking monoclonal antibody against the beta 1-integrin subunit completely inhibited adhesion of the spheroids to all three proteins. These results suggest that interactions between the alpha 5 beta 1-integrin and fibronectin mediate the formation of ovarian carcinoma spheroids and that their adhesion to extracellular matrix proteins at sites of secondary tumor growth may be mediated by a complex interaction between multiple integrins and their ligands.",
"The molecular mechanisms orchestrating peritoneal and hematogenous metastases of ovarian cancer cells are assumed to be distinct. We studied the p90RSK family of serine/threonine kinases that lie downstream the RAS-ERK/MAPK pathway and modulate a variety of cellular processes including cell proliferation, survival, motility and invasiveness. We found the RSK1 and RSK2 isoforms expressed in a number of human ovarian cancer cell lines, where they played redundant roles in sustaining in vitro motility and invasiveness. In vivo, silencing of both RSK1 and RSK2 almost abrogated short-term and long-term metastatic engraftment of ovarian cancer cells in the peritoneum. In addition, RSK1/RSK2 silenced cells failed to colonize the lungs after intravenous injection and to form hematogenous metastasis from subcutaneous xenografts. RSK1/RSK2 suppression resulted in lessened ovarian cancer cell spreading on endogenous fibronectin (FN). Mechanistically, RSK1/RSK2 knockdown diminished FN transcription, α5β1 integrin activation and TGF-β1 translation. Reduced endogenous FN deposition and TGF-β1 secretion depended on the lack of activating phosphorylation of the transcription/translation factor YB-1 by p90RSK. Altogether data show how p90RSK activates a self-reinforcing cell autonomous pro-adhesive circuit necessary for metastatic seeding of ovarian cancer cells. Thus, p90RSK inhibitors might hinder both the hematogenous and the peritoneal metastatic spread of human ovarian cancer."
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Increasing HIV diagnosis is important for combatting HIV.
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Increasing HIV diagnosis is important for combatting HIV. We invited individuals aged ≥ 13 years seeking voluntary HIV testing at Mildmay Clinic in Uganda to undertake a computer or audio-computer-assisted self-interview to facilitate post-test counseling. We evaluated first-visit data from 12,233 consenting individuals between January 2011 and October 2013. HIV prevalence was 39.0%. Of those with HIV, 37.2% already knew they were infected. Undiagnosed infection was associated with not being single, screening positive for depression (aOR 1.16, 95% CI 1.04-1.28), and screening for harmful drinking behavior (aOR 1.23, 95% CI 1.10-1.39). The odds of retesting subsequent to HIV diagnosis were lower for males (aOR 0.80, 95% CI 0.70-0.92) and those screening positive for harmful drinking behavior (aOR 0.77, 95% CI 0.66-0.88). Retesting was also associated with higher education and perceived social status below 'better off'. Our findings reiterate the value of population-based HIV surveys to provide estimates of testing coverage.
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[
"In the context of the ANRS 12249 Treatment as Prevention (TasP) trial, we investigated perceptions of regular and repeat HIV-testing in rural KwaZulu-Natal (South Africa), an area of very high HIV prevalence and incidence. We conducted two qualitative studies, before (2010) and during the early implementation stages of the trial (2013-2014), to appreciate the evolution in community perceptions of repeat HIV-testing over this period of rapid changes in HIV-testing and treatment approaches. Repeated focus group discussions were organized with young adults, older adults and mixed groups. Repeat and regular HIV-testing was overall well perceived before, and well received during, trial implementation. Yet community members were not able to articulate reasons why people might want to test regularly or repeatedly, apart from individual sexual risk-taking. Repeat home-based HIV-testing was considered as feasible and convenient, and described as more acceptable than clinic-based HIV-testing, mostly because of privacy and confidentiality. However, socially regulated discourses around appropriate sexual behaviour and perceptions of stigma and prejudice regarding HIV and sexual risk-taking were consistently reported. This study suggests several avenues to improve HIV-testing acceptability, including implementing diverse and personalised approaches to HIV-testing and care, and providing opportunities for antiretroviral therapy initiation and care at home.",
"Insufficient data are available from single cohort studies to allow estimation of the prognosis of HIV-1 infected, treatment-naive patients who start highly active antiretroviral therapy (HAART). The ART Cohort Collaboration, which includes 13 cohort studies from Europe and North America, was established to fill this knowledge gap. We analysed data on 12,574 adult patients starting HAART with a combination of at least three drugs. Data were analysed by intention-to-continue-treatment, ignoring treatment changes and interruptions. We considered progression to a combined endpoint of a new AIDS-defining disease or death, and to death alone. The prognostic model that generalised best was a Weibull model, stratified by baseline CD4 cell count and transmission group. FINDINGS During 24,310 person-years of follow up, 1094 patients developed AIDS or died and 344 patients died. Baseline CD4 cell count was strongly associated with the probability of progression to AIDS or death: compared with patients starting HAART with less than 50 CD4 cells/microL, adjusted hazard ratios were 0.74 (95% CI 0.62-0.89) for 50-99 cells/microL, 0.52 (0.44-0.63) for 100-199 cells/microL, 0.24 (0.20-0.30) for 200-349 cells/microL, and 0.18 (0.14-0.22) for 350 or more CD4 cells/microL. Baseline HIV-1 viral load was associated with a higher probability of progression only if 100,000 copies/microL or above. Other independent predictors of poorer outcome were advanced age, infection through injection-drug use, and a previous diagnosis of AIDS. The probability of progression to AIDS or death at 3 years ranged from 3.4% (2.8-4.1) in patients in the lowest-risk stratum for each prognostic variable, to 50% (43-58) in patients in the highest-risk strata. The CD4 cell count at initiation was the dominant prognostic factor in patients starting HAART. Our findings have important implications for clinical management and should be taken into account in future treatment guidelines.",
"Routine screening for HIV infection leads to early detection and treatment. We examined patient characteristics associated with repeated screening in a high prevalence country. We analyzed data from a cohort of 5,229 adults presenting for rapid HIV testing in the outpatient departments of 2 South African hospitals from November 2006 to August 2010. Patients were eligible if they were ≥18 years, reported no previous diagnosis with HIV infection, and not pregnant. Before testing, participants completed a questionnaire including gender, age, HIV testing history, health status, and knowledge about HIV and acquaintances with HIV. Enrollment HIV test results and CD4 counts were abstracted from the medical record. We present prevalence of HIV infection and median CD4 counts by HIV testing history (first-time vs. repeat). We estimated adjusted relative risks (ARR's) for repeat testing by demographics, health status, and knowledge of HIV and others with HIV in a generalized linear model. Of 4,877 participants with HIV test results available, 26% (N = 1258) were repeat testers. Repeat testers were less likely than first-time testers to be HIV-infected (34% vs. 54%, p<0.001). Median CD4 count was higher among repeat than first-time testers (201/uL vs. 147/uL, p<0.001). Among those HIV negative at enrollment (N = 2,499), repeat testing was more common among those with family or friends living with HIV (ARR 1.50, 95% CI: 1.33-1.68), women (ARR: 1.24, 95% CI: 1.11-1.40), and those self-reporting very good health (ARR: 1.28, 95% CI: 1.12-1.45). In this high prevalence setting, repeat testing was common among those undergoing HIV screening, and was associated with female sex, lower prevalence of HIV infection, and higher CD4 counts at diagnosis.",
"Optimally, expanded HIV testing programs should reduce barriers to testing while attracting new and high-risk testers. We assessed barriers to testing and HIV risk among clients participating in mobile voluntary counseling and testing (MVCT) campaigns in four rural villages in the Kilimanjaro Region of Tanzania. Between December 2007 and April 2008, 878 MVCT participants and 506 randomly selected community residents who did not access MVCT were surveyed. Gender-specific logistic regression models were used to describe differences in socioeconomic characteristics, HIV exposure risk, testing histories, HIV related stigma, and attitudes toward testing between MVCT participants and community residents who did not access MVCT. Gender-specific logistic regression models were used to describe differences in socioeconomic characteristics, HIV exposure risk, testing histories, HIV related stigma, and attitudes toward testing, between the two groups. MVCT clients reported greater HIV exposure risk (OR 1.20 [1.04 to 1.38] for males; OR 1.11 [1.03 to 1.19] for females). Female MVCT clients were more likely to report low household expenditures (OR 1.47 [1.04 to 2.05]), male clients reported higher rates of unstable income sources (OR 1.99 [1.22 to 3.24]). First-time testers were more likely than non-testers to cite distance to testing sites as a reason for not having previously tested (OR 2.17 [1.05 to 4.48] for males; OR 5.95 [2.85 to 12.45] for females). HIV-related stigma, fears of testing or test disclosure, and not being able to leave work were strongly associated with non-participation in MVCT (ORs from 0.11 to 0.84). MVCT attracted clients with increased exposure risk and fewer economic resources; HIV related stigma and testing-related fears remained barriers to testing. MVCT did not disproportionately attract either first-time or frequent repeat testers. Educational campaigns to reduce stigma and fears of testing could improve the effectiveness of MVCT in attracting new and high-risk populations."
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-Aminobutyric acidergic dysfunction and immune activation in schizophrenia: a multimodal imaging study
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γ-Aminobutyric acidergic (GABAergic) dysfunction and immune activation have been implicated in the pathophysiology of schizophrenia. Preclinical evidence suggests that inflammation-related abnormalities may contribute to GABAergic alterations in the brain, but this has never been investigated in vivo in humans. In this multimodal imaging study, we quantified cerebral GABA plus macromolecule (GABA+) levels in antipsychotic-naive people at clinical high risk for psychosis and in healthy volunteers. We investigated for the first time the association between GABA+ levels and expression of translocator protein 18 kDa (TSPO; a marker of microglial activation) using positron emission tomography (PET).
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[
"Neuroinflammation is associated with a broad spectrum of neurodegenerative and psychiatric diseases. The core process in neuroinflammation is activation of microglia, the innate immune cells of the brain. We measured the neuroinflammatory response produced by a systemic administration of the Escherichia coli lipopolysaccharide (LPS; also called endotoxin) in humans with the positron emission tomography (PET) radiotracer [11C]PBR28, which binds to translocator protein, a molecular marker that is up-regulated by microglial activation. In addition, inflammatory cytokines in serum and sickness behavior profiles were measured before and after LPS administration to relate brain microglial activation with systemic inflammation and behavior. Eight healthy male subjects each had two 120-min [11C]PBR28 PET scans in 1 d, before and after an LPS challenge. LPS (1.0 ng/kg, i.v.) was administered 180 min before the second [11C]PBR28 scan. LPS administration significantly increased [11C]PBR28 binding 30-60%, demonstrating microglial activation throughout the brain. This increase was accompanied by an increase in blood levels of inflammatory cytokines, vital sign changes, and sickness symptoms, well-established consequences of LPS administration. To our knowledge, this is the first demonstration in humans that a systemic LPS challenge induces robust increases in microglial activation in the brain. This imaging paradigm to measure brain microglial activation with [11C]PBR28 PET provides an approach to test new medications in humans for their putative antiinflammatory effects.",
"Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS) measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis. In SZ, unimodal studies gave mixed results, as increased, decreased, or unaltered GABA levels were reported depending on region, disease phase, and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signaling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ. Unimodal studies in BD revealed again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate, N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology. Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy, and functional-biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving from GABA MRS unimodal-descriptive to causal level, and for integrating GABA results into a more comprehensive interpretation of mental disorder pathophysiology.",
"Gamma-butyric acid (GABA) dysfunction has been implicated in the pathophysiology of schizophrenia and its cognitive deficits. Proton magnetic resonance spectroscopy (MRS) was used to test the hypothesis that older participants with schizophrenia have lower anterior cingulate GABA levels compared with older control participants. One-hundred forty-five participants completed this study. For detection of GABA, spectra were acquired from the medial frontal/anterior cingulate cortex using a macromolecule-suppressed MEGA-PRESS sequence. Patients were evaluated for psychopathology and all participants completed neuropsychological tests of working memory, processing speed and functional capacity. GABA levels were significantly lower in the older participants with schizophrenia (n=31) compared with the older control (n=37) group (P=0.003) but not between the younger control (n=40) and schizophrenia (n=29) groups (P=0.994). Age strongly predicted GABA levels in the schizophrenia group accounting for 42% of the variance, but the effect of age was less in the control group accounting for 5.7% of the variance. GABA levels were specifically related to working memory but not processing speed performance, functional capacity, or positive or negative symptom severity. This is the largest MRS study of GABA in schizophrenia and the first to examine GABA without macromolecule contamination, a potentially significant issue in previous studies. GABA levels more rapidly declined with advancing age in the schizophrenia compared with the control group. Interventions targeted at halting the decline or increasing GABA levels may improve functional outcomes and quality of life as patients with schizophrenia age.",
"Up-regulation of gamma-aminobutyric acidA (GABAA) receptors and decreased GABA uptake in the cerebral cortex of schizophrenics suggest altered GABAergic transmission, which could be caused by primary disturbance of GABA synapses or by decreased production of the transmitter. Decreased production could be due to a shutdown in GABA production or to loss of GABA neurons caused by cell death or their failure to migrate to the cortex during brain development. To discriminate between these possibilities, we quantified levels of messenger RNA (mRNA) for the 67-kd isoform of glutamic acid decarboxylase (GAD), the key enzyme in GABA synthesis, and the number and laminar distribution of GAD mRNA--expressing neurons in the dorsolateral prefrontal cortex (DLPFC) of schizophrenics and matched controls, using in situ hybridization-histochemistry, densitometry, and cell-counting methods. These data were compared with the total number of neurons, the number of small, round or ovoid neurons 8 to 15 microns in diameter, and overall frontal lobe volume. As a control, mRNA levels for type II calcium-calmodulin-dependent protein kinase (CamIIK) were quantified. Schizophrenics showed a pronounced decrease in GAD mRNA levels in neurons of layer I (40%) and layer II (48%) and an overall 30% decrease in layers III to VI. There were also strong overall reductions in GAD mRNA levels. The CamIIK mRNA levels showed no significant differences between samples. No differences were found in the total number of neurons nor in small, round or ovoid neurons, which should include a majority of the GABA cells. Prefrontal gray and white matter volume did not differ significantly between controls and schizophrenics. The prefrontal cortex of schizophrenics shows reduced expression for GAD in the absence of significant cell loss. This may be brought about by an activity-dependent down-regulation associated with the functional hypoactivity of the DLPFC. The lack of significant alterations in cell numbers in the DLPFC and frontal lobe volume in schizophrenics also implies that overall cortical neuronal migration had not been compromised in development. Previous reports of altered neuronal distribution in the subcortical white matter of schizophrenic brains in comparison with that of controls may indicate disturbances of migration or programmed cell death in the cortical subplate, leading to altered connection formation in the overlying cortex of schizophrenics and activity-dependent down-regulation of neurotransmitter-related gene expression.",
"Positron emission tomography (PET) imaging of the 18 kDa translocator protein (TSPO) has been used to investigate whether microglial activation, an indication of neuroinflammation, is evident in the brain of adults with schizophrenia. Interpretation of these studies is confounded by potential modulatory effects of antipsychotic medication on microglial activity. In the first such study in antipsychotic-free schizophrenia, we have used [11C](R)-PK11195 PET to compare TSPO availability in a predominantly antipsychotic-naive group of moderate-to-severely symptomatic unmedicated patients (n=8), similarly symptomatic medicated patients with schizophrenia taking risperidone or paliperidone by regular intramuscular injection (n=8), and healthy comparison subjects (n=16). We found no evidence for increased TSPO availability in antipsychotic-free patients compared with healthy controls (mean difference 4%, P=0.981). However, TSPO availability was significantly elevated in medicated patients (mean increase 88%, P=0.032) across prefrontal (dorsolateral, ventrolateral, orbital), anterior cingulate and parietal cortical regions. In the patients, TSPO availability was also strongly correlated with negative symptoms measured using the Positive and Negative Syndrome Scale across all the brain regions investigated (r=0.651-0.741). We conclude that the pathophysiology of schizophrenia is not associated with microglial activation in the 2-6 year period following diagnosis. The elevation in the medicated patients may be a direct effect of the antipsychotic, although this study cannot exclude treatment resistance and/or longer illness duration as potential explanations. It also remains to be determined whether it is present only in a subset of patients, represents a pro- or anti-inflammatory state, its association with primary negative symptoms, and whether there are significant differences between antipsychotics.",
"According to the recommendations of the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Neurocognition Committee, one of the desired characteristics of a cognitive battery for assessing cognition in schizophrenia studies and clinical trials is the availability of normative data. This report describes normative data collected on the Brief Assessment of Cognition in Schizophrenia (BACS) from 404 healthy controls with demographic characteristics matching the 2005 United States Census of English-speakers. The six test measures demonstrated the expected pattern of correlations with age, gender, and education. Individual test scores were converted into standardized (T and z) scores and composite scores that were corrected for age and gender. An education-correction factor was calculated and recommended only for non-schizophrenia patients. Eight different verbal memory tests were found to have equivalent levels of difficulty."
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Management of acute hyperammonemia
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Acute hyperammonemia may induce a neurologic impairment leading to an acute life-threatening condition. Coma duration, ammonia peak level, and hyperammonemia duration are the main risk factors of hyperammonemia-related neurologic deficits and death. In children, hyperammonemia is mainly caused by severe liver failure and inborn errors of metabolism. In an acute setting, obtaining reliable plasma ammonia levels can be challenging because of the preanalytical difficulties that need to be addressed carefully. The management of hyperammonemia includes 1) identification of precipitating factors and cerebral edema presence, 2) a decrease in ammonia production by reducing protein intake and reversing catabolism, and 3) ammonia removal with pharmacologic treatment and, in the most severe cases, with extracorporeal therapies. In case of severe coma, transcranial Doppler ultrasound could be the method of choice to noninvasively monitor cerebral blood flow and titrate therapies.
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[
"Hyponatremia is a marker of poor prognosis in patients with cirrhosis. This analysis aimed to assess if hyponatremia also has prognostic value in patients with acute-on-chronic liver failure (ACLF), a syndrome characterized by acute decompensation of cirrhosis, organ failure(s) and high short-term mortality. We performed an analysis of the Chronic Liver Failure Consortium CANONIC database in 1,341 consecutive patients admitted to 29 European centers with acute decompensation of cirrhosis (including ascites, gastrointestinal bleeding, hepatic encephalopathy, or bacterial infections, or any combination of these), both with and without associated ACLF (301 and 1,040 respectively). Of the 301 patients with ACLF, 24.3% had hyponatremia at inclusion compared to 12.3% of 1,040 patients without ACLF (P <0.001). Model for end-stage liver disease, Child-Pugh and chronic liver failure-SOFA scores were significantly higher in patients with ACLF and hyponatremia compared to those without hyponatremia. The presence of hyponatremia (at inclusion or during hospitalization) was a predictive factor of survival both in patients with and without ACLF. The presence of hyponatremia and ACLF was found to have an independent effect on 90-day survival after adjusting for the potential confounders. Hyponatremia in non-ACLF patients nearly doubled the risk (hazard ratio (HR) 1.81 (1.33 to 2.47)) of dying at 90 days. However, when considering patients with both factors (ACLF and hyponatremia) the relative risk of dying at 90 days was significantly higher (HR 6.85 (3.85 to 12.19) than for patients without both factors. Patients with hyponatremia and ACLF had a three-month transplant-free survival of only 35.8% compared to 58.7% in those with ACLF without hyponatremia (P <0.001). The presence of hyponatremia is an independent predictive factor of survival in patients with ACLF. In cirrhosis, outcome of patients with ACLF is dependent on its association with hyponatremia.",
"Plasma osmolalities were measured in 100 normal, 100 general hospital and 100 intensive care patients, and compared with the osmolalities calculated from the plasma concentrations of sodium, potassium, glucose and urea, using five different published formulae. The mean osmolar gaps in the 100 consecutive intensive care patients and the 100 general hospital patients were not significantly different from the mean osmolar gap in the 100 normal individuals. The formula which gave the least difference between the measured and calculated osmolality was 2 X Na + urea + glucose, where the concentrations of sodium, urea and glucose were measured in mmol/l.",
"We sought to determine the effect of acute electrolyte and osmolar shifts on brain volume and neurologic function in patients with liver failure and severe hepatic encephalopathy. Retrospective analysis of brain CT scans and clinical data. Tertiary care hospital ICUs. Patients with acute or acute-on-chronic liver failure and severe hepatic encephalopathy. Clinically indicated CT scans and serum laboratory studies. Change in intracranial cerebrospinal fluid volume between sequential CT scans was measured as a biomarker of acute brain volume change. Corresponding changes in serum osmolality, chemistry measurements, and Glasgow Coma Scale were determined. Associations with cerebrospinal fluid volume change and Glasgow Coma Scale change for initial volume change assessments were identified by Spearman's correlations (rs) and regression models. Consistency of associations with repeated assessments was evaluated using generalized estimating equations. Forty patients were included. Median baseline osmolality was elevated (310 mOsm/Kg [296-321 mOsm/Kg]) whereas sodium was normal (137 mEq/L [134-142 mEq/L]). Median initial osmolality change was 9 mOsm/kg (5-17 mOsm/kg). Neuroimaging consistent with increased brain volume occurred in 27 initial assessments (68%). Cerebrospinal fluid volume change was more strongly correlated with osmolality (r = 0.70; p = 4 × 10) than sodium (r = 0.28; p = 0.08) change. Osmolality change was independently associated with Glasgow Coma Scale change (p = 1 × 10) and cerebrospinal fluid volume change (p = 2.7 × 10) in initial assessments and in generalized estimating equations using all 103 available assessments. Acute decline in osmolality was associated with brain swelling and neurologic deterioration in severe hepatic encephalopathy. Minimizing osmolality decline may avoid neurologic deterioration.",
"Urea cycle defects presenting early in life with hyperammonemia remain difficult to treat and commonly necessitate liver transplantation. Gene therapy has the potential to prevent hyperammonemic episodes while awaiting liver transplantation, and possibly also to avert the need for transplantation altogether. Ornithine transcarbamylase (OTC) deficiency, the most prevalent urea cycle disorder, provides an ideal model for the development of liver-targeted gene therapy. While we and others have successfully cured the spf(ash) mouse model of OTC deficiency using adeno-associated virus (AAV) vectors, a major limitation of this model is the presence of residual OTC enzymatic activity which confers a mild phenotype without clinically significant hyperammonemia. To better model severe disease we devised a strategy involving AAV2/8-mediated delivery of a short hairpin RNA (shRNA) to specifically knockdown residual endogenous OTC messenger RNA (mRNA). This strategy proved highly successful with vector-treated mice developing severe hyperammonemia and associated neurological impairment. Using this system, we showed that the dose of an AAV rescue construct encoding the murine OTC (mOTC) cDNA required to prevent hyperammonemia is fivefold lower than that required to control orotic aciduria. This result is favorable for clinical translation as it indicates that the threshold for therapeutic benefit is likely to be lower than indicated by earlier studies.",
"Recent in vivo studies using proton magnetic resonance (1H-MR) spectroscopy showed low levels of myo-inositol in the brain in hepatic encephalopathy; the pathogenetic relevance of this observation is unclear. Myo-inositol and glutamine levels in the brain were studied in vivo by 1H-MR spectroscopy in patients with hypo-osmolarity and hepatic encephalopathy. A patient with severe plasma hypo-osmolarity (222 mOsm/L) had almost undetectable signals for myo-inositol and glutamine/glutamate in the brain. Both signals reappeared after normalization of plasma osmolarity, suggesting that both myo-inositol and glutamine were released as organic osmolytes from the brain. A decreased cerebral myo-inositol signal is also found in low-grade hepatic encephalopathy but is accompanied by an increased glutamine signal. Cirrhotics without hepatic encephalopathy have near-normal inositol signals, and patients with acquired immunodeficiency syndrome encephalopathy have increased inositol signals. The 1H-MR spectroscopic myo-inositol signal in the human brain predominantly reflects an osmosensitive inositol pool. It is hypothesized that its depletion in latent hepatic encephalopathy points to a disturbance of cell volume homeostasis in the brain as an early pathogenetic event. This may partly be caused by a hyperammonemia-induced glutamine accumulation in the brain.",
"Cerebral edema is common in severe hepatic encephalopathy and may be life threatening. Bolus 23.4% hypertonic saline improves surveillance neuromonitoring scores, although its mechanism of action is not clearly established. We investigated the hypothesis that bolus hypertonic saline decreases cerebral edema in severe hepatic encephalopathy utilizing a quantitative technique to measure brain and cerebrospinal fluid volume changes. Retrospective analysis of serial CT scans, and clinical data for a case-control series were performed. ICUs of a tertiary care hospital. Patients with severe hepatic encephalopathy treated with 23.4% hypertonic saline and control patients who did not receive 23.4% hypertonic saline. 23.4% hypertonic saline bolus administration. We used clinically obtained CT scans to measure volumes of the ventricles, intracranial cerebrospinal fluid, and brain using a previously validated semiautomated technique (Analyze Direct, Overland Park, KS). Volumes before and after 23.4% hypertonic saline were compared with Wilcoxon signed rank test. Associations among total cerebrospinal fluid volume, ventricular volume, serum sodium, and Glasgow Coma Scale scores were assessed using Spearman rank correlation test. Eleven patients with 18 administrations of 23.4% hypertonic saline met inclusion criteria. Total cerebrospinal fluid (median, 47.6 mL [35.1-69.4 mL] to 61.9 mL [47.7-87.0 mL]; p < 0.001) and ventricular volumes (median, 8.0 mL [6.9-9.5 mL] to 9.2 mL [7.8-11.9 mL]; p = 0.002) increased and Glasgow Coma Scale scores improved (median, 4 [3-6] to 7 [6-9]; p = 0.008) after 23.4% hypertonic saline. In contrast, total cerebrospinal fluid and ventricular volumes decreased in untreated control patients. Serum sodium increase was associated with increase in total cerebrospinal fluid volume (r = 0.83, p < 0.001), and change in total cerebrospinal fluid volume was associated with ventricular volume change (r = 0.86; p < 0.001). Total cerebrospinal fluid and ventricular volumes increased after 23.4% hypertonic saline, consistent with a reduction in brain tissue volume. Total cerebrospinal fluid and ventricular volume change may be useful quantitative measures to assess cerebral edema in severe hepatic encephalopathy.",
"Dialysis disequilibrium syndrome (DDS) is characterized by the neurologic deterioration and cerebral edema that occurs after hemodialysis. To investigate the pathogenesis of DDS, the effects of rapid hemodialysis on brain electrolytes, urea, and several organic osmolytes were studied in the rat. Forty-two h after bilateral ureteral ligation, 11 uremic rats were hemodialyzed for 90 min, yielding a decrease in plasma urea from 96 +/- 4 to 44 +/- 5 mM (p < 0.01). This group was compared with 10 uremic and 11 nonuremic animals that were not dialyzed. In dialyzed animals, compared with nondialyzed uremic controls, there was an increase in brain water (3.98 +/- 0.02 versus 3.77 +/- 0.02 L/kg dry wt; P < 0.01) and the brain to plasma (urea) ratio (1.32 versus 0.65). There was no significant difference in the brain content of sodium and potassium between groups. The retention of brain urea, despite the large decrease in plasma urea concentration, was able to account for the increase in brain water observed in rapidly dialyzed animals. Major organic osmolytes in the brain, including glutamine, glutamate, taurine and myoinositol, did not increase significantly after rapid dialysis. Cerebral edema in this model of DDS was primarily due to a large brain-to-plasma urea gradient, not to the formation of organic osmolytes."
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Chemoradiation therapy is the mainstay for treatment of locally advanced, borderline resectable pancreatic cancer
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: Chemoradiation therapy is the mainstay for treatment of locally advanced, borderline resectable pancreatic cancer. Pharmacologic ascorbate (P-AscH
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[
"Pancreatic carcinoma is a leading cause of cancer-related mortality. Approximately 30% of pancreatic cancer patients present with locally advanced, unresectable nonmetastatic disease. For these patients, two therapeutic options exist: systemic chemotherapy or chemoradiotherapy. Within this context, the optimal technique for pancreatic irradiation is not clearly defined. A search to identify relevant studies was undertaken using the Medline database. All Phase III randomized trials evaluating the modalities of radiotherapy in locally advanced pancreatic cancer were included, as were some noncontrolled Phase II and retrospective studies. An expert panel convened with members of the Radiation Therapy Oncology Group and GERCOR cooperative groups to review identified studies and prepare the guidelines. Each member of the working group independently evaluated five endpoints: total dose, target volume definition, radiotherapy planning technique, dose constraints to organs at risk, and quality assurance. Based on this analysis of the literature, we recommend either three-dimensional conformal radiation therapy or intensity-modulated radiation therapy to a total dose of 50 to 54 Gy at 1.8 to 2 Gy per fraction. We propose gross tumor volume identification to be followed by an expansion of 1.5 to 2 cm anteriorly, posteriorly, and laterally, and 2 to 3 cm craniocaudally to generate the planning target volume. The craniocaudal margins can be reduced with the use of respiratory gating. Organs at risk are liver, kidneys, spinal cord, stomach, and small bowel. Stereotactic body radiation therapy should not be used for pancreatic cancer outside of clinical trials. Radiotherapy quality assurance is mandatory in clinical trials. These consensus recommendations are proposed for use in the development of future trials testing new chemotherapy combinations with radiotherapy. Not all of these recommendations will be appropriate for trials testing radiotherapy dose or dose intensity concepts.",
"More than half of human colorectal cancers (CRCs) carry either KRAS or BRAF mutations and are often refractory to approved targeted therapies. We found that cultured human CRC cells harboring KRAS or BRAF mutations are selectively killed when exposed to high levels of vitamin C. This effect is due to increased uptake of the oxidized form of vitamin C, dehydroascorbate (DHA), via the GLUT1 glucose transporter. Increased DHA uptake causes oxidative stress as intracellular DHA is reduced to vitamin C, depleting glutathione. Thus, reactive oxygen species accumulate and inactivate glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Inhibition of GAPDH in highly glycolytic KRAS or BRAF mutant cells leads to an energetic crisis and cell death not seen in KRAS and BRAF wild-type cells. High-dose vitamin C impairs tumor growth in Apc/Kras(G12D) mutant mice. These results provide a mechanistic rationale for exploring the therapeutic use of vitamin C for CRCs with KRAS or BRAF mutations.",
"Ascorbate (AscH-) functions as a versatile reducing agent. At pharmacological doses (P-AscH-; [plasma AscH-] ≥≈20mM), achievable through intravenous delivery, oxidation of P-AscH- can produce a high flux of H2O2 in tumors. Catalase is the major enzyme for detoxifying high concentrations of H2O2. We hypothesize that sensitivity of tumor cells to P-AscH- compared to normal cells is due to their lower capacity to metabolize H2O2. Rate constants for removal of H2O2 (kcell) and catalase activities were determined for 15 tumor and 10 normal cell lines of various tissue types. A differential in the capacity of cells to remove H2O2 was revealed, with the average kcell for normal cells being twice that of tumor cells. The ED50 (50% clonogenic survival) of P-AscH- correlated directly with kcell and catalase activity. Catalase activity could present a promising indicator of which tumors may respond to P-AscH-.",
"Salicylic acid and anthocyanidins are known as plant-derived antioxidants, but also can provoke paradoxically seeming prooxidant effects in vitro. These prooxidant effects are connected to the potential of salicylic acid and anthocyanidins to induce apoptosis selectively in tumor cells in vitro and to inhibit tumor growth in animal models. Several epidemiological studies have shown that salicylic acid and its prodrug acetylsalicylic acid are tumor-preventive for humans. The mechanism of salicylic acid- and anthocyanidin-dependent antitumor effects has remained enigmatic so far. Extracellular apoptosis-inducing reactive oxygen species signaling through the NO/peroxynitrite and the HOCl signaling pathway specifically induces apoptosis in transformed cells. Tumor cells have acquired resistance against intercellular reactive oxygen species signaling through expression of membrane-associated catalase. Here, we show that salicylic acid and anthocyanidins inactivate tumor cell protective catalase and thus reactive apoptosis-inducing intercellular reactive oxygen species signaling of tumor cells and the mitochondrial pathway of apoptosis Salicylic acid inhibits catalase directly through its potential to transform compound I of catalase into the inactive compound II. In contrast, anthocyanidins provoke a complex mechanism for catalase inactivation that is initiated by anthocyanidin-mediated inhibition of NO dioxygenase. This allows the formation of extracellular singlet oxygen through the reaction between H(2)O(2) and peroxynitrite, amplification through a caspase8-dependent step and subsequent singlet oxygen-mediated inactivation of catalase. The combination of salicylic acid and anthocyanidins allows for a remarkable synergistic effect in apoptosis induction. This effect may be potentially useful to elaborate novel therapeutic approaches and crucial for the interpretation of epidemiological results related to the antitumor effects of secondary plant compounds.",
"The discovery that oxidized vitamin C, dehydroascorbate (DHA), can induce oxidative stress and cell death in cancer cells has rekindled interest in the use of high dose vitamin C (VC) as a cancer therapy. However, high dose VC has shown limited efficacy in clinical trials, possibly due to the decreased bioavailability of oral VC. Because human erythrocytes express high levels of Glut1, take up DHA, and reduce it to VC, we tested how erythrocytes might impact high dose VC therapies. Cancer cells are protected from VC-mediated cell death when co-cultured with physiologically relevant numbers of erythrocytes. Pharmacological doses of VC induce oxidative stress, GSH depletion, and increased glucose flux through the oxidative pentose phosphate pathway (PPP) in erythrocytes. Incubation of erythrocytes with VC induced hemolysis, which was exacerbated in erythrocytes from glucose-6-phosphate dehydrogenase (G6PD) patients and rescued by antioxidants. Thus, erythrocytes protect cancer cells from VC-induced oxidative stress and undergo hemolysis in vitro, despite activation of the PPP. These results have implications on the use of high dose VC in ongoing clinical trials and highlight the importance of the PPP in the response to oxidative stress.",
"To test the hypothesis that mitochondrial DNA (mtDNA) is more prone to reactive oxygen species (ROS) damage than nuclear DNA, a continuous flux of hydrogen peroxide (H2O2) was produced with the glucose/glucose oxidase system. Using a horse radish peroxidase (HRPO)-based colorimetric assay to detect H2O2, glucose oxidase (GO; 12 mU/ml) produced 95 microM of H2O2 in 1 h, whereas only 46 microM of hydrogen peroxide accumulated in the presence of SV40-transformed human fibroblasts ( approximately 1 x 10(6). DNA damage was assessed in the mitochondira and three nuclear regions using a quantitative PCR assay. GO (12 mU/ml) resulted in more damage to the mitochondrial DNA (2.250 +/- 0.045 lesions/10 kb) than in any one of three nuclear targets, which included the non-expressed beta-globin locus (0.436 +/- 0.029 lesions/10 kb); and the active DNA polymerase b gene (0.442 +/- 0.037 lesions/10 kb); and the active hprt gene (0.310 +/- 0.025). Damage to the mtDNA occurred within 15 min of GO treatment, whereas nuclear damage did not appear until after 30 min, and reached a maximum after 60 min. Repair of mitochondrial damage after a 15 min GO (6 mU/ml) treatment was examined. Mitochondria repaired 50% of the damage after 1 h, and by 6 h all the damage was repaired. Higher doses of GO-generated H202, or more extended treatment periods, lead to mitochondrial DNA damage which was not repaired. Mitochondrial function was monitored using the MTT (3,(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide) assay. A 15 min treatment with 6 mU/ml of GO decreased mitochondrial activity to 80% of the control; the activity recovered completely within 1 h after damage. These data show that GO-generated H202 causes acute damage to mtDNA and function, and demonstrate that this organelle is an important site for the cellular toxicity of ROS.",
"Copper- and zinc-containing superoxide dismutase, manganese-containing superoxide dismutase, catalase, and glutathione peroxidase form the primary enzymic defense against toxic oxygen reduction metabolites. Such metabolites have been implicated in the damage brought about by ionizing radiation, as well as in the effects of several cytostatic compounds. These enzymes were analyzed in 31 different human normal diploid and neoplastic cell lines and for comparison in 15 normal human tissues. The copper- and zinc-containing superoxide dismutase appeared to be slightly lower in malignant cell lines in general as compared to normal tissues. The content of manganese superoxide dismutase was more variable than the content of the copper- and zinc-containing enzyme. Contrary to what has been suggested before, this enzyme did not appear to be generally lower in malignant cells compared to normal cells. One cell line, of mesothelioma origin (P27), was extremely abundant in manganese-containing superoxide dismutase; the concentration was almost an order of magnitude larger than in the richest normal tissue. Catalase was very variable both among the normal tissues and among the malignant cells, whereas glutathione peroxidase was more evenly distributed. In neither case was a general difference between normal cells and tissues and malignant cells apparent. The myocardial damage brought about by doxorubicin has been linked to toxic oxygen metabolites; particularly, an effect on the glutathione system has been noted. The heart is one of the tissues which have a low concentration of enzymes which protect against hydroperoxides. However, the deviation from other tissues is probably not large enough to provide a full explanation for the high doxorubicin susceptibility. In the present survey, no obvious relationship between generally assumed resistance to ionizing radiation or to radical-producing drugs and cellular content of any of the enzymes could be demonstrated."
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Two-axis control of a spin 3/2 qubit in natural Ge
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Holes confined in quantum dots have gained considerable interest in the past few years due to their potential as spin qubits. Here we demonstrate two-axis control of a spin 3/2 qubit in natural Ge. The qubit is formed in a hut wire double quantum dot device. The Pauli spin blockade principle allowed us to demonstrate electric dipole spin resonance by applying a radio frequency electric field to one of the electrodes defining the double quantum dot. Coherent hole spin oscillations with Rabi frequencies reaching 140 MHz are demonstrated and dephasing times of 130 ns are measured. The reported results emphasize the potential of Ge as a platform for fast and electrically tunable hole spin qubit devices.
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[
"We have measured carbon nanotube quantum dots with multiple electrostatic gates and used the resulting enhanced control to investigate a nanotube double quantum dot. Transport measurements reveal honeycomb charge stability diagrams as a function of two nearly independent gate voltages. The device can be tuned from weak to strong interdot tunnel-coupling regimes, and the transparency of the leads can be controlled independently. We extract values of energy-level spacings, capacitances, and interaction energies for this system. This ability to control electron interactions in the quantum regime in a molecular conductor is important for applications such as quantum computation.",
"The spin of an electron or a nucleus in a semiconductor naturally implements the unit of quantum information--the qubit. In addition, because semiconductors are currently used in the electronics industry, developing qubits in semiconductors would be a promising route to realize scalable quantum information devices. The solid-state environment, however, may provide deleterious interactions between the qubit and the nuclear spins of surrounding atoms, or charge and spin fluctuations arising from defects in oxides and interfaces. For materials such as silicon, enrichment of the spin-zero (28)Si isotope drastically reduces spin-bath decoherence. Experiments on bulk spin ensembles in (28)Si crystals have indeed demonstrated extraordinary coherence times. However, it remained unclear whether these would persist at the single-spin level, in gated nanostructures near amorphous interfaces. Here, we present the coherent operation of individual (31)P electron and nuclear spin qubits in a top-gated nanostructure, fabricated on an isotopically engineered (28)Si substrate. The (31)P nuclear spin sets the new benchmark coherence time (>30 s with Carr-Purcell-Meiboom-Gill (CPMG) sequence) of any single qubit in the solid state and reaches >99.99% control fidelity. The electron spin CPMG coherence time exceeds 0.5 s, and detailed noise spectroscopy indicates that--contrary to widespread belief--it is not limited by the proximity to an interface. Instead, decoherence is probably dominated by thermal and magnetic noise external to the device, and is thus amenable to further improvement.",
"Controlling decoherence is the biggest challenge in efforts to develop quantum information hardware. Single electron spins in gallium arsenide are a leading candidate among implementations of solid-state quantum bits, but their strong coupling to nuclear spins produces high decoherence rates. Group IV semiconductors, on the other hand, have relatively low nuclear spin densities, making them an attractive platform for spin quantum bits. However, device fabrication remains a challenge, particularly with respect to the control of materials and interfaces. Here, we demonstrate state preparation, pulsed gate control and charge-sensing spin readout of hole spins confined in a Ge-Si core-shell nanowire. With fast gating, we measure T(1) spin relaxation times of up to 0.6 ms in coupled quantum dots at zero magnetic field. Relaxation time increases as the magnetic field is reduced, which is consistent with a spin-orbit mechanism that is usually masked by hyperfine contributions.",
"Nanofabricated quantum bits permit large-scale integration but usually suffer from short coherence times due to interactions with their solid-state environment. The outstanding challenge is to engineer the environment so that it minimally affects the qubit, but still allows qubit control and scalability. Here, we demonstrate a long-lived single-electron spin qubit in a Si/SiGe quantum dot with all-electrical two-axis control. The spin is driven by resonant microwave electric fields in a transverse magnetic field gradient from a local micromagnet, and the spin state is read out in the single-shot mode. Electron spin resonance occurs at two closely spaced frequencies, which we attribute to two valley states. Thanks to the weak hyperfine coupling in silicon, a Ramsey decay timescale of 1 μs is observed, almost two orders of magnitude longer than the intrinsic timescales in GaAs quantum dots, whereas gate operation times are comparable to those reported in GaAs. The spin echo decay time is ~40 μs, both with one and four echo pulses, possibly limited by intervalley scattering. These advances strongly improve the prospects for quantum information processing based on quantum dots.",
"Quantum-dot spin qubits characteristically use oscillating magnetic or electric fields, or quasi-static Zeeman field gradients, to realize full qubit control. For the case of three confined electrons, exchange interaction between two pairs allows qubit rotation around two axes, hence full control, using only electrostatic gates. Here, we report initialization, full control, and single-shot readout of a three-electron exchange-driven spin qubit. Control via the exchange interaction is fast, yielding a demonstrated 75 qubit rotations in less than 2 ns. Measurement and state tomography are performed using a maximum-likelihood estimator method, allowing decoherence, leakage out of the qubit state space, and measurement fidelity to be quantified. The methods developed here are generally applicable to systems with state leakage, noisy measurements and non-orthogonal control axes."
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Epigenetic Classification of Pediatric Brain Tumors
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Despite significant improvements in pediatric brain tumor therapy and outcome, too many children still die of disease, and too many survivors experience significant sequelae as a result of conventional therapies. The molecular characterization of pediatric brain tumors has afforded tremendous insight into the basic biology and clinical management of these deadly childhood diseases. Genomic, epigenomic, and transcriptional profiling have facilitated the identification of significant heterogeneity among previously uniform disease entities. In particular, DNA methylation profiling has emerged as a robust tool for identifying key disease-specific subgroups that can exhibit distinct clinical outcomes. These approaches, which also complement classic histologic techniques, can suggest key mechanistic underpinnings of tumorigenesis and open the door for better informed and more tailored therapy. By leveraging the results of large-scale classifications of disease cohorts, novel driver mutations and pathways can be uncovered, enabling the generation of faithful animal models, promoting targeted drug design, informing developmental biology, and ultimately translating into improved clinical management. In this review, progress in the epigenetic classification of common malignant pediatric brain tumors, namely medulloblastoma, ependymoma, high-grade glioma, atypical teratoid/rhabdoid tumor, and central nervous system embryonal tumors, will be discussed, and the potential role of DNA methylation profiling as a frontline diagnostic modality will be emphasized.
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[
"Members of the nuclear factor-κB (NF-κB) family of transcriptional regulators are central mediators of the cellular inflammatory response. Although constitutive NF-κB signalling is present in most human tumours, mutations in pathway members are rare, complicating efforts to understand and block aberrant NF-κB activity in cancer. Here we show that more than two-thirds of supratentorial ependymomas contain oncogenic fusions between RELA, the principal effector of canonical NF-κB signalling, and an uncharacterized gene, C11orf95. In each case, C11orf95-RELA fusions resulted from chromothripsis involving chromosome 11q13.1. C11orf95-RELA fusion proteins translocated spontaneously to the nucleus to activate NF-κB target genes, and rapidly transformed neural stem cells--the cell of origin of ependymoma--to form these tumours in mice. Our data identify a highly recurrent genetic alteration of RELA in human cancer, and the C11orf95-RELA fusion protein as a potential therapeutic target in supratentorial ependymoma.",
"Intracranial germ cell tumors (iGCTs) are the second most common brain tumors among children under 14 in Japan. The World Health Organization classification recognizes several subtypes of iGCTs, which are conventionally subclassified into pure germinoma or non-germinomatous GCTs. Recent exhaustive genomic studies showed that mutations of the genes involved in the MAPK and/or PI3K pathways are common in iGCTs; however, the mechanisms of how different subtypes develop, often as a mixed-GCT, are unknown. To elucidate the pathogenesis of iGCTs, we investigated 61 GCTs of various subtypes by genome-wide DNA methylation profiling. We showed that pure germinomas are characterized by global low DNA methylation, a unique epigenetic feature making them distinct from all other iGCTs subtypes. The patterns of methylation strongly resemble that of primordial germ cells (PGC) at the migration phase, possibly indicating the cell of origin for these tumors. Unlike PGC, however, hypomethylation extends to long interspersed nuclear element retrotransposons. Histologically and epigenetically distinct microdissected components of mixed-GCTs shared identical somatic mutations in the MAPK or PI3K pathways, indicating that they developed from a common ancestral cell.",
"Medulloblastoma is a malignant childhood brain tumour comprising four discrete subgroups. Here, to identify mutations that drive medulloblastoma, we sequenced the entire genomes of 37 tumours and matched normal blood. One-hundred and thirty-six genes harbouring somatic mutations in this discovery set were sequenced in an additional 56 medulloblastomas. Recurrent mutations were detected in 41 genes not yet implicated in medulloblastoma; several target distinct components of the epigenetic machinery in different disease subgroups, such as regulators of H3K27 and H3K4 trimethylation in subgroups 3 and 4 (for example, KDM6A and ZMYM3), and CTNNB1-associated chromatin re-modellers in WNT-subgroup tumours (for example, SMARCA4 and CREBBP). Modelling of mutations in mouse lower rhombic lip progenitors that generate WNT-subgroup tumours identified genes that maintain this cell lineage (DDX3X), as well as mutated genes that initiate (CDH1) or cooperate (PIK3CA) in tumorigenesis. These data provide important new insights into the pathogenesis of medulloblastoma subgroups and highlight targets for therapeutic development.",
"We examined 18 atypical teratoid and rhabdoid tumors of the brain and 7 renal and 4 extrarenal rhabdoid tumors for mutations in the candidate rhabdoid tumor suppressor gene, INI1. Fifteen tumors had homozygous deletions of one or more exons of the INI1 gene, and the other 14 tumors demonstrated mutations. Germ-line mutations of INI1 were identified in four children, one with an atypical teratoid tumor of the brain and three with renal rhabdoid tumors. These studies suggest that INI1 is a tumor suppressor gene involved in rhabdoid tumors of the brain, kidney, and other extrarenal sites.",
"Current treatment for medulloblastoma, which includes postoperative radiotherapy and 1 year of chemotherapy, does not cure many children with high-risk disease. We aimed to investigate the effectiveness of risk-adapted radiotherapy followed by a shortened period of dose-intense chemotherapy in children with medulloblastoma. After resection, patients were classified as having average-risk medulloblastoma (< or = 1.5 cm2 residual tumour and no metastatic disease) or high-risk medulloblastoma (> 1.5 cm2 residual disease or metastatic disease localised to neuraxis) medulloblastoma. All patients received risk-adapted craniospinal radiotherapy (23.4 Gy for average-risk disease and 36.0-39.6 Gy for high-risk disease) followed by four cycles of cyclophosphamide-based, dose-intensive chemotherapy. Patients were assessed regularly for disease status and treatment side-effects. The primary endpoint was 5-year event-free survival; we also measured overall survival. This study is registered with ClinicalTrials.gov, number NCT00003211. Of 134 children with medulloblastoma who underwent treatment (86 average-risk, 48 high-risk), 119 (89%) completed the planned protocol. No treatment-related deaths occurred. 5-year overall survival was 85% (95% CI 75-94) in patients in the average-risk group and 70% (54-84) in those in the high-risk group (p=0.04); 5-year event-free survival was 83% (73-93) and 70% (55-85), respectively (p=0.046). For the 116 patients whose histology was reviewed centrally, histological subtype correlated with 5-year event-free survival (p=0.04): 84% (74-95) for classic histology, 77% (49-100) for desmoplastic tumours, and 57% (33-80) for large-cell anaplastic tumours. Risk-adapted radiotherapy followed by a shortened schedule of dose-intensive chemotherapy can be used to improve the outcome of patients with high-risk medulloblastoma.",
"Clinical and pathological features of 52 infants and children with atypical teratoid/rhabdoid tumor (ATT/RhT) of the central nervous system are defined. This tumor is typically misdiagnosed as a primitive neuroectodermal tumor (PNET) primarily because 70% of ATT/RhTs contain fields indistinguishable from classic PNETs. Separation of these two tumor types is crucial because the prognosis for ATT/RhT is given even when treatment includes surgery with or without radio and/or chemotherapy. These tumors are most common in infants less than 2 years of age. The cases described in this study arose in intracranially in all but one instance, although one-third had already spread throughout the subarachnoid space at presentation. Clinical signs and symptoms and radiological features do not distinguish ATT/RhTs from PNETs. The tumors are composed entirely (13%) or partly (77%) or rhabdoid cells. Seventy percent contains fields of typical PNET alone or in combinations with mesenchymal and/r epithelial elements. The immunohistochemical profile is unique: epithelial membrane antigen, vimentin, and smooth-muscle actin are positive in the majority of tumors and markers for germ-cell tumors are consistently negative. Abnormalities of chromosome 22 distinguish ATT/RhTs from PNETs, which typically display an i(17q) abnormality.",
"Expression of L1 cell adhesion molecule (L1CAM) is associated with poor prognosis in a variety of human carcinomas including breast, ovarian and pancreatic ductal adenocarcinoma (PDAC). Recently we reported that L1CAM induces sustained nuclear factor kappa B (NF-κB) activation by augmenting the autocrine production of interleukin 1 beta (IL-1β), a process dependent on interaction of L1CAM with integrins. In the present study, we demonstrate that transforming growth factor β1 (TGF-β1) treatment of breast carcinoma (MDA-MB231) and PDAC (BxPc3) cell lines induces an EMT (epithelial to mesenchymal transition)-like phenotype and leads to the expression of L1CAM. In MDA-MB231 cells, up-regulation of L1CAM augmented expression of IL-1β and NF-κB activation, which was reversed by depletion of L1CAM, L1CAM-binding membrane cytoskeleton linker protein ezrin, β1-integrin or focal adhesion kinase (FAK). Over-expression of L1CAM not only induced NF-κB activation but also mediated the phosphorylation of FAK and Src. Phosphorylation was not induced in cells expressing a mutant form of L1CAM (L1-RGE) devoid of the integrin-binding site. FAK- and Src-phosphorylation were inhibited by knock-down of various components of the integrin signalling pathway such as β1- and α5-integrins, integrin-linked kinase (ILK), FAK and the phosphoinositide 3-kinase (PI3K) subunit p110β. In summary, these results reveal that during EMT, L1CAM promotes IL-1β expression through a process dependent on integrin signalling and supports a motile and invasive tumour cell phenotype. We also identify important novel downstream effector molecules of the L1CAM-integrin signalling crosstalk that help to understand the molecular mechanisms underlying L1CAM-promoted tumour progression."
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A novel de novo c.1324C>T (p.(Gln442Ter)) PPP3CA variant causes severe epileptic encephalopathy and dysmorphism
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PPP3CA encodes calmodulin-binding catalytic subunit of calcineurin, a ubiquitously expressed calcium/calmodulin-regulated protein phosphatase. Recently de novo PPP3CA variants were reported as a cause of disease in 12 subjects presenting with epileptic encephalopathy and dysmorphic features. We describe a boy with similar phenotype and severe early onset epileptic encephalopathy in whom a novel de novo c.1324C>T (p.(Gln442Ter)) PPP3CA variant was found by whole exome sequencing. Western blot experiments in patient's cells (EBV transformed lymphocytes and neuronal cells derived through reprogramming) indicate that despite normal mRNA abundance the protein expression level is strongly reduced both for the mutated and wild-type protein. By in vitro studies with recombinant protein expressed in E. coli we show that c.1324C>T (p.(Gln442Ter)) results in constitutive activation of the enzyme. Our results confirm the role of PPP3CA defects in pathogenesis of a distinct neurodevelopmental disorder including severe epilepsy and dysmorphism and provide further functional clues regarding the pathogenic mechanism.
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"The genomes of individuals with severe, undiagnosed developmental disorders are enriched in damaging de novo mutations (DNMs) in developmentally important genes. Here we have sequenced the exomes of 4,293 families containing individuals with developmental disorders, and meta-analysed these data with data from another 3,287 individuals with similar disorders. We show that the most important factors influencing the diagnostic yield of DNMs are the sex of the affected individual, the relatedness of their parents, whether close relatives are affected and the parental ages. We identified 94 genes enriched in damaging DNMs, including 14 that previously lacked compelling evidence of involvement in developmental disorders. We have also characterized the phenotypic diversity among these disorders. We estimate that 42% of our cohort carry pathogenic DNMs in coding sequences; approximately half of these DNMs disrupt gene function and the remainder result in altered protein function. We estimate that developmental disorders caused by DNMs have an average prevalence of 1 in 213 to 1 in 448 births, depending on parental age. Given current global demographics, this equates to almost 400,000 children born per year.",
"It is well established that autism spectrum disorders (ASD) have a strong genetic component; however, for at least 70% of cases, the underlying genetic cause is unknown. Under the hypothesis that de novo mutations underlie a substantial fraction of the risk for developing ASD in families with no previous history of ASD or related phenotypes--so-called sporadic or simplex families--we sequenced all coding regions of the genome (the exome) for parent-child trios exhibiting sporadic ASD, including 189 new trios and 20 that were previously reported. Additionally, we also sequenced the exomes of 50 unaffected siblings corresponding to these new (n = 31) and previously reported trios (n = 19), for a total of 677 individual exomes from 209 families. Here we show that de novo point mutations are overwhelmingly paternal in origin (4:1 bias) and positively correlated with paternal age, consistent with the modest increased risk for children of older fathers to develop ASD. Moreover, 39% (49 of 126) of the most severe or disruptive de novo mutations map to a highly interconnected β-catenin/chromatin remodelling protein network ranked significantly for autism candidate genes. In proband exomes, recurrent protein-altering mutations were observed in two genes: CHD8 and NTNG1. Mutation screening of six candidate genes in 1,703 ASD probands identified additional de novo, protein-altering mutations in GRIN2B, LAMC3 and SCN1A. Combined with copy number variant (CNV) data, these results indicate extreme locus heterogeneity but also provide a target for future discovery, diagnostics and therapeutics.",
"Calcium/calcineurin signaling is critical for normal cellular physiology. Abnormalities in this pathway cause many diseases, including podocytopathy; therefore, understanding the mechanisms that underlie the regulation of calcium/calcineurin signaling is essential. Here, we showed that critical components of calcium/calcineurin signaling, including TRPC6, PPP3CA, PPP3CB, PPP3R1, and NFATC3, are the targets of the microRNA-30 family (miR-30s). We found that these 5 genes are highly expressed as mRNA, but the level of the proteins is low in normal podocytes. Conversely, protein levels were markedly elevated in podocytes from rats treated with puromycin aminonucleoside (PAN) and from patients with focal segmental glomerulosclerosis (FSGS). In both FSGS patients and PAN-treated rats, miR-30s were downregulated in podocytes. In cultured podocytes, PAN or a miR-30 sponge increased TRPC6, PPP3CA, PPP3CB, PPP3R1, and NFATC3 expression; calcium influx; intracellular Ca2+ concentration; and calcineurin activity. Moreover, NFATC3 nuclear translocation, synaptopodin degradation, integrin β3 (ITGB3) activation, and actin fiber loss, which are downstream of calcium/calcineurin signaling, were induced by miR-30 reduction but blocked by the calcineurin inhibitor FK506. Podocyte-specific expression of the miR-30 sponge in mice increased calcium/calcineurin pathway component protein expression and calcineurin activity. The mice developed podocyte foot process effacement and proteinuria, which were prevented by FK506. miR-30s also regulated calcium/calcineurin signaling in cardiomyocytes. Together, our results identify miR-30s as essential regulators of calcium/calcineurin signaling.",
"Exome sequencing of 343 families, each with a single child on the autism spectrum and at least one unaffected sibling, reveal de novo small indels and point substitutions, which come mostly from the paternal line in an age-dependent manner. We do not see significantly greater numbers of de novo missense mutations in affected versus unaffected children, but gene-disrupting mutations (nonsense, splice site, and frame shifts) are twice as frequent, 59 to 28. Based on this differential and the number of recurrent and total targets of gene disruption found in our and similar studies, we estimate between 350 and 400 autism susceptibility genes. Many of the disrupted genes in these studies are associated with the fragile X protein, FMRP, reinforcing links between autism and synaptic plasticity. We find FMRP-associated genes are under greater purifying selection than the remainder of genes and suggest they are especially dosage-sensitive targets of cognitive disorders."
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Dynamic DNA methylation in response to Blumeria graminis f. sp. tritici in wheat
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DNA methylation is dynamically involved in plant immunity, but little information is known about its roles in plant interactions with biotrophic fungi, especially in temperate grasses such as wheat (Triticum aestivum). Using wheat diploid progenitor Aegilops tauschii accession AL8/78, the genome of which has been sequenced, we assessed the extent of DNA methylation in response to infection with Blumeria graminis f. sp. tritici (Bgt), which causes powdery mildew. Upon Bgt infection, ARGONAUTE4a (AGO4a) was significantly downregulated in A. tauschii, which was accompanied by a substantial reduction in AGO4a-sorted 24-nt siRNA levels, especially for genes near transposable elements (TAGs). Bisulfite sequencing revealed abundant differentially methylated regions (DMRs) with CHH hypomethylation. TAGs bearing CHH-hypomethylated DMRs were enriched for 'response to stress' functions, including receptor kinase, peroxidase, and pathogenesis-related genes. Virus-induced gene silencing (VIGS) of a DOMAINS REARRANGED METHYLASE 2 (DRM2) homolog enhanced plant resistance to Bgt. The effect of CHH hypomethylation was exemplified by the upregulation of a pathogenesis-related β-1,3-glucanse gene implicated in Bgt defense. These findings support the idea that dynamic DNA methylation represents a regulatory layer in the complex mechanism of plant immunity, which could be exploited to improve disease resistance in common wheat.
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"The Arabidopsis DNA glycosylase/lyase ROS1 participates in active DNA demethylation by a base-excision pathway. ROS1 has been shown to be required for demethylating a transgene promoter. To determine the function of ROS1 in demethylating endogenous loci, we carried out bisulfite-sequencing analysis of several transposons and other genes in the ros1 mutant. In the wild-type, although CpG sites at the majority of these loci are heavily methylated, many of the CpXpG and CpXpX sites have low levels of methylation or are not at all methylated. However, these CpXpG and CpXpX sites become heavily methylated in the ros1 mutant. Associated with this increased DNA methylation, these loci show decreased expression in the ros1 mutant. Our results suggest that active DNA demethylation is important in pruning the methylation patterns of the genome, and even the normally \"silent\" transposons are under dynamic control by both methylation and demethylation. This dynamic control may be important in keeping the plant epigenome plastic so that it can efficiently respond to developmental and environmental cues.",
"Cytosine DNA methylation protects eukaryotic genomes by silencing transposons and harmful DNAs, but also regulates gene expression during normal development. Loss of CG methylation in the Arabidopsis thaliana met1 and ddm1 mutants causes varied and stochastic developmental defects that are often inherited independently of the original met1 or ddm1 mutation. Loss of non-CG methylation in plants with combined mutations in the DRM and CMT3 genes also causes a suite of developmental defects. We show here that the pleiotropic developmental defects of drm1 drm2 cmt3 triple mutant plants are fully recessive, and unlike phenotypes caused by met1 and ddm1, are not inherited independently of the drm and cmt3 mutations. Developmental phenotypes are also reversed when drm1 drm2 cmt3 plants are transformed with DRM2 or CMT3, implying that non-CG DNA methylation is efficiently re-established by sequence-specific signals. We provide evidence that these signals include RNA silencing though the 24-nucleotide short interfering RNA (siRNA) pathway as well as histone H3K9 methylation, both of which converge on the putative chromatin-remodeling protein DRD1. These signals act in at least three partially intersecting pathways that control the locus-specific patterning of non-CG methylation by the DRM2 and CMT3 methyltransferases. Our results suggest that non-CG DNA methylation that is inherited via a network of persistent targeting signals has been co-opted to regulate developmentally important genes.",
"Gene silencing in eukaryotes is associated with the formation of heterochromatin, a complex of proteins and DNA that block transcription. Heterochromatin is characterized by the methylation of cytosine nucleotides of the DNA, the methylation of histone H3 at lysine 9 (H3 Lys 9), and the specific binding of heterochromatin protein 1 (HP1) to methylated H3 Lys 9 (refs 1-7). Although the relationship between these chromatin modifications is generally unknown, in the fungus Neurospora crassa, DNA methylation acts genetically downstream of H3 Lys 9 methylation. Here we report the isolation of KRYPTONITE, a methyltransferase gene specific to H3 Lys 9, identified in a mutant screen for suppressors of gene silencing at the Arabidopsis thaliana SUPERMAN (SUP) locus. Loss-of-function kryptonite alleles resemble mutants in the DNA methyltransferase gene CHROMOMETHYLASE3 (CMT3), showing loss of cytosine methylation at sites of CpNpG trinucleotides (where N is A, C, G or T) and reactivation of endogenous retrotransposon sequences. We show that CMT3 interacts with an Arabidopsis homologue of HP1, which in turn interacts with methylated histones. These data suggest that CpNpG DNA methylation is controlled by histone H3 Lys 9 methylation, through interaction of CMT3 with methylated chromatin.",
"Detection of plant and animal pathogens triggers a massive transcriptional reprogramming, which is directed by chromatin-based processes, and ultimately results in antimicrobial immunity. Although the implication of histone modifications in orchestrating biotic stress-induced transcriptional reprogramming has been well characterized, very little was known, until recently, about the role of DNA methylation and demethylation in this process. In this review, we summarize recent findings on the dynamics and biological relevance of DNA methylation and demethylation in plant immunity against nonviral pathogens. In particular, we report the implications of these epigenetic regulatory processes in the transcriptional and co-transcriptional control of immune-responsive genes and discuss their relevance in fine-tuning antimicrobial immune responses. Finally, we discuss the possible yet elusive role of DNA methylation and demethylation in systemic immune responses, transgenerational immune priming, and de novo epiallelism, which could be adaptive.",
"Chemical modifications to DNA and histone proteins form a complex regulatory network that modulates chromatin structure and genome function. The epigenome refers to the complete description of these potentially heritable changes across the genome. The composition of the epigenome within a given cell is a function of genetic determinants, lineage, and environment. With the sequencing of the human genome completed, investigators now seek a comprehensive view of the epigenetic changes that determine how genetic information is made manifest across an incredibly varied background of developmental stages, tissue types, and disease states. Here we review current research efforts, with an emphasis on large-scale studies, emerging technologies, and challenges ahead.",
"RNA-directed DNA methylation (RdDM) is the major small RNA-mediated epigenetic pathway in plants. RdDM requires a specialized transcriptional machinery that comprises two plant-specific RNA polymerases - Pol IV and Pol V - and a growing number of accessory proteins, the functions of which in the RdDM mechanism are only partially understood. Recent work has revealed variations in the canonical RdDM pathway and identified factors that recruit Pol IV and Pol V to specific target sequences. RdDM, which transcriptionally represses a subset of transposons and genes, is implicated in pathogen defence, stress responses and reproduction, as well as in interallelic and intercellular communication.",
"b-1,3-Glucanases are a group of pathogenesis related proteins that have been reported to be involved in plant defense against pathogens in many other plant pathogen systems. However, it was not clear if these genes play similar role in wheat (Triticum aestivum L.) against Puccinia striiformis f. sp. tritici (Pst), the stripe rust pathogen. To investigate the role of b-1,3-glucanase (EC3.2.1.39) in the resistance response of wheat (cv. Suwon11) to stripe rust, a wheat b-1,3-glucanase gene induced by Pst, designated as TaGlu, was cloned and characterized.TaGlu was predicted to encode a basic protein of 334 amino acids. Quantitative real-time PCR analyses revealed that the transcription of TaGlu was induced during both compatible and incompatible interactions with Pst, but the transcription level was much higher in the incompatible interaction than that in the compatible interaction. TaGlu also showed noticeable induction of gene expression in young green leaf tissues treated with salicylic acid, methyl jasmonate or ethylene. Immunogold labeling assays showed that the enzyme were localized mainly in the host cell wall and over the extra haustorial matrix, and the labeling densities were found significantly higher in the incompatible interaction than those in the compatible interaction.",
"DNA methylation is an epigenetic mark that silences transposable elements (TEs) and repeats. Whereas the establishment and maintenance of DNA methylation are relatively well understood, little is known about their dynamics and biological relevance in plant and animal innate immunity. Here, we show that some TEs are demethylated and transcriptionally reactivated during antibacterial defense in Arabidopsis. This effect is correlated with the down-regulation of key transcriptional gene silencing factors and is partly dependent on an active demethylation process. DNA demethylation restricts multiplication and vascular propagation of the bacterial pathogen Pseudomonas syringae in leaves and, accordingly, some immune-response genes, containing repeats in their promoter regions, are negatively regulated by DNA methylation. This study provides evidence that DNA demethylation is part of a plant-induced immune response, potentially acting to prime transcriptional activation of some defense genes linked to TEs/repeats.",
"Deciphering the multiple layers of epigenetic regulation that control transcription is critical to understanding how plants develop and respond to their environment. Using sequencing-by-synthesis technology we directly sequenced the cytosine methylome (methylC-seq), transcriptome (mRNA-seq), and small RNA transcriptome (smRNA-seq) to generate highly integrated epigenome maps for wild-type Arabidopsis thaliana and mutants defective in DNA methyltransferase or demethylase activity. At single-base resolution we discovered extensive, previously undetected DNA methylation, identified the context and level of methylation at each site, and observed local sequence effects upon methylation state. Deep sequencing of smRNAs revealed a direct relationship between the location of smRNAs and DNA methylation, perturbation of smRNA biogenesis upon loss of CpG DNA methylation, and a tendency for smRNAs to direct strand-specific DNA methylation in regions of RNA-DNA homology. Finally, strand-specific mRNA-seq revealed altered transcript abundance of hundreds of genes, transposons, and unannotated intergenic transcripts upon modification of the DNA methylation state.",
"Small RNAs play important regulatory roles in most eukaryotes, but only a small proportion of these molecules have been identified. We sequenced more than two million small RNAs from seedlings and the inflorescence of the model plant Arabidopsis thaliana. Known and new microRNAs (miRNAs) were among the most abundant of the nonredundant set of more than 75,000 sequences, whereas more than half represented lower abundance small interfering RNAs (siRNAs) that match repetitive sequences, intergenic regions, and genes. Individual or clusters of highly regulated small RNAs were readily observed. Targets of antisense RNA or miRNA did not appear to be preferentially associated with siRNAs. Many genomic regions previously considered featureless were found to be sites of numerous small RNAs."
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Microplastic Contamination in Bottled Water
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Eleven globally sourced brands of bottled water, purchased in 19 locations in nine different countries, were tested for microplastic contamination using Nile Red tagging. Of the 259 total bottles processed, 93% showed some sign of microplastic contamination. After accounting for possible background (lab) contamination, an average of 10.4 microplastic particles >100 um in size per liter of bottled water processed were found. Fragments were the most common morphology (66%) followed by fibers. Half of these particles were confirmed to be polymeric in nature using FTIR spectroscopy with polypropylene being the most common polymer type (54%), which matches a common plastic used for the manufacture of bottle caps. A small fraction of particles (4%) showed the presence of industrial lubricants. While spectroscopic analysis of particles smaller than 100 um was not possible, the adsorption of the Nile Red dye indicates that these particles are most probably plastic. Including these smaller particles (6.5-100 um), an average of 325 microplastic particles per liter of bottled water was found. Microplastic contamination range of 0 to over 10,000 microplastic particles per liter with 95% of particles being between 6.5 and 100 um in size. Data suggests the contamination is at least partially coming from the packaging and/or the bottling process itself. Given the prevalence of the consumption of bottled water across the globe, the results of this study support the need for further studies on the impacts of micro- and nano- plastics on human health.
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"Plastics pollution in the ocean is an area of growing concern, with research efforts focusing on both the macroplastic (>5mm) and microplastic (<5mm) fractions. In the 1990 s it was recognized that a minor source of microplastic pollution was derived from liquid hand-cleansers that would have been rarely used by the average consumer. In 2009, however, the average consumer is likely to be using microplastic-containing products on a daily basis, as the majority of facial cleansers now contain polyethylene microplastics which are not captured by wastewater plants and will enter the oceans. Four microplastic-containing facial cleansers available in New Zealand supermarkets were used to quantify the size of the polythelene fragments. Three-quarters of the brands had a modal size of <100 microns and could be immediately ingested by planktonic organisms at the base of the food chain. Over time the microplastics will be subject to UV-degradation and absorb hydrophobic materials such as PCBs, making them smaller and more toxic in the long-term. Marine scientists need to educate the public to the dangers of using products that pose an immediate and long-term threat to the health of the oceans and the food we eat.",
"Large plastic (>5mm) and microplastic (0.315-5mm) debris were collected from 25 beaches along the Hong Kong coastline. More than 90% consisted of microplastics. Among the three groups of microplastic debris, expanded polystyrene (EPS) represented 92%, fragments represented 5%, and pellets represented 3%. The mean microplastic abundance for Hong Kong was 5595items/m(2). This number is higher than international averages, indicating that Hong Kong is a hotspot of marine plastic pollution. Microplastic abundance was significantly higher on the west coast than on the east coast, indicating that the Pearl River, which is west of Hong Kong, may be a potential source of plastic debris. The amounts of large plastic and microplastic debris of the same types (EPS and fragments) were positively correlated, suggesting that the fragmentation of large plastic material may increase the quantity of beach microplastic debris.",
"Neuston samples were collected at 21 stations during an ~700 nautical mile (~1300 km) expedition in July 2012 in the Laurentian Great Lakes of the United States using a 333 μm mesh manta trawl and analyzed for plastic debris. Although the average abundance was approximately 43,000 microplastic particles/km², station 20, downstream from two major cities, contained over 466,000 particles/km², greater than all other stations combined. SEM analysis determined nearly 20% of particles less than 1 mm, which were initially identified as microplastic by visual observation, were aluminum silicate from coal ash. Many microplastic particles were multi-colored spheres, which were compared to, and are suspected to be, microbeads from consumer products containing microplastic particles of similar size, shape, texture and composition. The presence of microplastics and coal ash in these surface samples, which were most abundant where lake currents converge, are likely from nearby urban effluent and coal burning power plants.",
"When mammals strand, they present a unique opportunity to obtain insights into their ecology. In May 2013, three True's beaked whales (two adult females and a female calf) stranded on the north and west coasts of Ireland and the contents of their stomachs and intestines were analysed for anthropogenic debris. A method for identifying microplastics ingested by larger marine organisms was developed. Microplastics were identified throughout the digestive tract of the single whale that was examined for the presence of microplastics. The two adult females had macroplastic items in their stomachs. Food remains recovered from the adult whales consisted of mesopelagic fish (Benthosema glaciale, Nansenia spp., Chauliodius sloani) and cephalopods, although trophic transfer has been discussed, it was not possible to ascertain whether prey were the source of microplastics. This is the first study to directly identify microplastics <5 mm in a cetacean species.",
"Microplastics are present in marine habitats worldwide and laboratory studies show this material can be ingested, yet data on abundance in natural populations is limited. This study documents microplastics in 10 species of fish from the English Channel. 504 Fish were examined and plastics found in the gastrointestinal tracts of 36.5%. All five pelagic species and all five demersal species had ingested plastic. Of the 184 fish that had ingested plastic the average number of pieces per fish was 1.90±0.10. A total of 351 pieces of plastic were identified using FT-IR Spectroscopy; polyamide (35.6%) and the semi-synthetic cellulosic material, rayon (57.8%) were most common. There was no significant difference between the abundance of plastic ingested by pelagic and demersal fish. Hence, microplastic ingestion appears to be common, in relatively small quantities, across a range of fish species irrespective of feeding habitat. Further work is needed to establish the potential consequences.",
"Human populations are using oceans as their household dustbins, and microplastic is one of the components which are not only polluting shorelines but also freshwater bodies globally. Microplastics are generally referred to particles with a size lower than 5 mm. These microplastics are tiny plastic granules and used as scrubbers in cosmetics, hand cleansers, air-blasting. These contaminants are omnipresent within almost all marine environments at present. The durability of plastics makes it highly resistant to degradation and through indiscriminate disposal they enter in the aquatic environment. Today, it is an issue of increasing scientific concern because these microparticles due to their small size are easily accessible to a wide range of aquatic organisms and ultimately transferred along food web. The chronic biological effects in marine organisms results due to accumulation of microplastics in their cells and tissues. The potential hazardous effects on humans by alternate ingestion of microparticles can cause alteration in chromosomes which lead to infertility, obesity, and cancer. Because of the recent threat of microplastics to marine biota as well as on human health, it is important to control excessive use of plastic additives and to introduce certain legislations and policies to regulate the sources of plastic litter. By setup various plastic recycling process or promoting plastic awareness programmes through different social and information media, we will be able to clean our sea dustbin in future.",
"Marine turtles are an iconic group of endangered animals threatened by debris ingestion. However, key aspects related to debris ingestion are still poorly known, including its effects on mortality and the original use of the ingested debris. Therefore, we analysed the impact of debris ingestion in 265 green turtles (Chelonia mydas) over a large geographical area and different habitats along the Brazilian coast. We determined the death rate due to debris ingestion and quantified the amount of debris that is sufficient to cause the death of juvenile green turtles. Additionally, we investigated the original use of the ingested debris. We found that a surprisingly small amount of debris was sufficient to block the digestive tract and cause death. We suggested that debris ingestion has a high death potential that may be masked by other causes of death. An expressive part of the ingested debris come from disposable and short-lived products.",
"Marine debris is widely recognized as a global environmental problem. One of its main components, microplastics, has been found in several sea salt samples from different countries, indicating that sea products are irremediably contaminated by microplastics. Previous studies show very confusing results, reporting amounts of microparticles (MPs) in salt ranging from zero to 680 MPs/kg, with no mention of the possible causes of such differences. Several errors in the experimental procedures used were found and are reported in the present work. Likewise, 21 different samples of commercial table salt from Spain have been analyzed for MPs content and nature. The samples comprise sea salts and well salts, before and after packing. The microplastic content found was of 50-280 MPs/kg salt, being polyethylene-terephthalate (PET) the most frequently found polymer, followed by polypropylene (PP) and polyethylene (PE), with no significant differences among all the samples. The results indicate that even though the micro-particles might originate from multiple sources, there is a background presence of microplastics in the environment.",
"Plastic debris is a growing contaminant of concern in freshwater environments, yet sources, transport, and fate remain unclear. This study characterized the quantity and morphology of floating micro- and macroplastics in 29 Great Lakes tributaries in six states under different land covers, wastewater effluent contributions, population densities, and hydrologic conditions. Tributaries were sampled three or four times each using a 333 μm mesh neuston net. Plastic particles were sorted by size, counted, and categorized as fibers/lines, pellets/beads, foams, films, and fragments. Plastics were found in all 107 samples, with a maximum concentration of 32 particles/m3 and a median of 1.9 particles/m3. Ninety-eight percent of sampled plastic particles were less than 4.75 mm in diameter and therefore considered microplastics. Fragments, films, foams, and pellets/beads were positively correlated with urban-related watershed attributes and were found at greater concentrations during runoff-event conditions. Fibers, the most frequently detected particle type, were not associated with urban-related watershed attributes, wastewater effluent contribution, or hydrologic condition. Results from this study add to the body of information currently available on microplastics in different environmental compartments, including unique contributions to quantify their occurrence and variability in rivers with a wide variety of different land-use characteristics while highlighting differences between surface samples from rivers compared with lakes.",
"The occurrence of microplastics (MPs) in saltwater bodies is relatively well studied, but nothing is known about their presence in most of the commercial salts that are widely consumed by humans across the globe. Here, we extracted MP-like particles larger than 149 μm from 17 salt brands originating from 8 different countries followed by the identification of their polymer composition using micro-Raman spectroscopy. Microplastics were absent in one brand while others contained between 1 to 10 MPs/Kg of salt. Out of the 72 extracted particles, 41.6% were plastic polymers, 23.6% were pigments, 5.50% were amorphous carbon, and 29.1% remained unidentified. The particle size (mean ± SD) was 515 ± 171 μm. The most common plastic polymers were polypropylene (40.0%) and polyethylene (33.3%). Fragments were the primary form of MPs (63.8%) followed by filaments (25.6%) and films (10.6%). According to our results, the low level of anthropogenic particles intake from the salts (maximum 37 particles per individual per annum) warrants negligible health impacts. However, to better understand the health risks associated with salt consumption, further development in extraction protocols are needed to isolate anthropogenic particles smaller than 149 μm."
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Auxin response factors in plant carotenoid biosynthesis and responses to abiotic stress
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Auxin response factors (ARFs) compose a family of transcription factors and have been found to play major roles in the process of plant growth and development. However, their roles in plant carotenoid biosynthesis and responses to abiotic stresses are rarely known to date. In the present study, we found that the
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"Myo-inositol-1-phosphate synthase (MIPS) is a key rate limiting enzyme in myo-inositol biosynthesis. The MIPS gene has been shown to improve tolerance to abiotic stresses in several plant species. However, its role in resistance to biotic stresses has not been reported. In this study, we found that expression of the sweet potato IbMIPS1 gene was induced by NaCl, polyethylene glycol (PEG), abscisic acid (ABA) and stem nematodes. Its overexpression significantly enhanced stem nematode resistance as well as salt and drought tolerance in transgenic sweet potato under field conditions. Transcriptome and real-time quantitative PCR analyses showed that overexpression of IbMIPS1 up-regulated the genes involved in inositol biosynthesis, phosphatidylinositol (PI) and ABA signalling pathways, stress responses, photosynthesis and ROS-scavenging system under salt, drought and stem nematode stresses. Inositol, inositol-1,4,5-trisphosphate (IP3 ), phosphatidic acid (PA), Ca(2+) , ABA, K(+) , proline and trehalose content was significantly increased, whereas malonaldehyde (MDA), Na(+) and H2 O2 content was significantly decreased in the transgenic plants under salt and drought stresses. After stem nematode infection, the significant increase of inositol, IP3 , PA, Ca(2+) , ABA, callose and lignin content and significant reduction of MDA content were found, and a rapid increase of H2 O2 levels was observed, peaked at 1 to 2 days and thereafter declined in the transgenic plants. This study indicates that the IbMIPS1 gene has the potential to be used to improve the resistance to biotic and abiotic stresses in plants.",
"Sweetpotato [Ipomoea batatas (L.) Lam], which contains high levels of antioxidants such as ascorbate and carotenoids in its storage root, is one of the healthiest foods, as well as one of the best starch crops for growth on marginal lands. In plants, carotenoid pigments are involved in light harvesting for photosynthesis and are also essential for photo-protection against excess light. As dietary antioxidants in humans, these compounds benefit health by alleviating aging-related diseases. The storage root of sweetpotato is a good source of both carotenoids and carbohydrates for human consumption. Therefore, metabolic engineering of sweetpotato to increase the content of useful carotenoids represents an important agricultural goal. This effort has been facilitated by cloning of most of the carotenoid biosynthetic genes, as well as the Orange gene involved in carotenoid accumulation. In this review, we describe our current understanding of the regulation of biosynthesis, accumulation and catabolism of carotenoids in sweetpotato. A deeper understanding of these topics should contribute to development of new sweetpotato cultivars with higher levels of nutritional carotenoids and abiotic stress tolerance.",
"Chitosan (CHT) antiviral activity has been further investigated in the pathosystem Phaseolus vulgaris - tobacco necrosis virus (TNV). CHT application elicited both callose apposition and ABA accumulation in leaf tissues, at 12 and 24h after treatment, respectively, and induced a high level of resistance against TNV. Besides, treatment with the ABA inhibitor nordihydroguaiaretic acid (NDGA), before CHT application, reduced both callose deposition and plant resistance to the virus, thus indicating the involvement of ABA in these processes. Exogenous application of ABA also induced a significant resistance to TNV, though this resistance was abolished by NDGA pre-treatment. These results, overall, indicate that the rise of ABA synthesis induced by chitosan plays an important role in enhancing callose deposition but the latter has only a partial effect on virus spreading, which must be constraint by other resistance mechanisms.",
"Sweetpotato highly produces carotenoids in storage roots. In this study, a cDNA encoding geranylgeranyl phyrophosphate synthase (GGPS), named IbGGPS, was isolated from sweetpotato storage roots. Green fluorescent protein (GFP) was fused to the C-terminus of IbGGPS to obtain an IbGGPS-GFP fusion protein that was transiently expressed in both epidermal cells of onion and leaves of tobacco. Confocal microscopic analysis determined that the IbGGPS-GFP protein was localized to specific areas of the plasma membrane of onion and chloroplasts in tobacco leaves. The coding region of IbGGPS was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis thaliana to obtain transgenic plants. High performance liquid chromatography (HPLC) analysis showed a significant increase of total carotenoids in transgenic plants. The seeds of transgenic and wild-type plants were germinated on an agar medium supplemented with polyethylene glycol (PEG). Transgenic seedlings grew significantly longer roots than wild-type ones did. Further enzymatic analysis showed an increased activity of superoxide dismutase (SOD) in transgenic seedlings. In addition, the level of malondialdehyde (MDA) was reduced in transgenics. qRT-PCR analysis showed altered expressions of several genes involved in the carotenoid biosynthesis in transgenic plants. These data results indicate that IbGGPS is involved in the biosynthesis of carotenoids in sweetpotato storage roots and likely associated with tolerance to osmotic stress.",
"Carotenoids play essential roles in various light-harvesting processes in plants and help protect the photosynthetic machinery from photo-oxidative damage. Orange genes, which play a role in carotenoid accumulation, have recently been isolated from several plant species, and their functions have been intensively investigated. The Orange gene (IbOr) of sweet potato [Ipomoea batatas (L.) Lam] helps maintain carotenoid homeostasis to improve plant tolerance to environmental stress. IbOr, a protein with strong holdase chaperone activity, directly interacts with phytoene synthase, a key enzyme involved in carotenoid biosynthesis, in plants under stress conditions, resulting in increased carotenoid accumulation and abiotic stress tolerance. In addition, IbOr interacts with the oxygen-evolving enhancer protein 2-1, a member of a protein complex in photosystem II that is denatured under heat stress. Transgenic sweet potato plants overexpressing IbOr showed enhanced tolerance to high temperatures (47 °C). These findings indicate that IbOr protects plants from environmental stress not only by controlling carotenoid biosynthesis, but also by directly stabilizing photosystem II. In this review, we discuss the functions of IbOr and Or proteins in other plant species and their possible biotechnological applications for molecular breeding for sustainable development on marginal lands.",
"Crop productivity is greatly affected by soil salinity, so improvement in salinity tolerance of crops is a major objective of many studies. We overexpressed the Arabidopsis thaliana SOS1 gene, which encodes a plasma membrane Na(+)/H(+) antiporter, in tobacco (Nicotiana tabacum cv. Xanthi-nc). Compared with nontransgenic plants, seeds from transgenic tobacco had better germination under 120 mM (mmol L(-1)) NaCl stress; chlorophyll loss in the transgenic seedlings treated with 360 mM NaCl was less; transgenic tobacco showed superior growth after irrigation with NaCl solutions; and transgenic seedlings with 150 mM NaCl stress accumulated less Na(+) and more K(+). In addition, roots of SOS1-overexpressing seedlings lost less K(+) instantaneously in response to 50 mM NaCl than control plants. These results showed that the A. thaliana SOS1 gene potentially can improve the salt tolerance of other plant species.",
"A sensitive approach based on electrospray ionization tandem mass spectrometry has been employed to profile membrane lipid molecular species in Arabidopsis undergoing cold and freezing stresses. Freezing at a sublethal temperature induced a decline in many molecular species of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) but induced an increase in phosphatidic acid (PA) and lysophospholipids. To probe the metabolic steps generating these changes, lipids of Arabidopsis deficient in the most abundant phospholipase D, PLD alpha, were analyzed. The PC content dropped only half as much, and PA levels rose only half as high in the PLD alpha-deficient plants as in wild-type plants. In contrast, neither PE nor PG levels decreased significantly more in wild-type plants than in PLD alpha-deficient plants. These data suggest that PC, rather than PE and PG, is the major in vivo substrate of PLD alpha. The action of PLD alpha during freezing is of special interest because Arabidopsis plants that are deficient in PLD alpha have improved tolerance to freezing. The greater loss of PC and increase in PA in wild-type plants as compared with PLD alpha-deficient plants may be responsible for destabilizing membrane bilayer structure, resulting in a greater propensity toward membrane fusion and cell death in wild-type plants."
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How do I get a list of all the rows in a table?
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The
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[
"Genes differentially expressed in different tissues, during development, or during specific pathologies are of foremost interest to both basic and pharmaceutical research. \"Transcript profiles\" or \"digital Northerns\" are generated routinely by partially sequencing thousands of randomly selected clones from relevant cDNA libraries. Differentially expressed genes can then be detected from variations in the counts of their cognate sequence tags. Here we present the first systematic study on the influence of random fluctuations and sampling size on the reliability of this kind of data. We establish a rigorous significance test and demonstrate its use on publicly available transcript profiles. The theory links the threshold of selection of putatively regulated genes (e.g., the number of pharmaceutical leads) to the fraction of false positive clones one is willing to risk. Our results delineate more precisely and extend the limits within which digital Northern data can be used.",
"In grapevine (Vitis vinifera), anthocyanins are responsible for most of the red, blue, and purple pigmentation found in the skin of berries. In cells, anthocyanins are synthesized in the cytoplasm and accumulated into the vacuole. However, little is known about the transport of these compounds through the tonoplast. Recently, the sequencing of the grapevine genome allowed us to identify genes encoding proteins with high sequence similarity to the Multidrug And Toxic Extrusion (MATE) family. Among them, we selected two genes as anthocyanin transporter candidates and named them anthoMATE1 (AM1) and AM3. The expression of both genes was mainly fruit specific and concomitant with the accumulation of anthocyanin pigment. Subcellular localization assays in grapevine hairy roots stably transformed with AM1 or AM3green fluorescent protein fusion protein revealed that AM1 and AM3 are primarily localized to the tonoplast. Yeast vesicles expressing anthoMATEs transported acylated anthocyanins in the presence of MgATP. Inhibitor studies demonstrated that AM1 and AM3 proteins act in vitro as vacuolar H(+)-dependent acylated anthocyanin transporters. By contrast, under our experimental conditions, anthoMATEs could not transport malvidin 3-O-glucoside or cyanidin 3-O-glucoside, suggesting that the acyl conjugation was essential for the uptake. Taken together, these results provide evidence that in vitro the two grapevine AM1 and AM3 proteins mediate specifically acylated anthocyanin transport.",
"We present an investigation of anthocyanin regulation over the entire petunia plant, determining the mechanisms governing complex floral pigmentation patterning and environmentally induced vegetative anthocyanin synthesis. DEEP PURPLE (DPL) and PURPLE HAZE (PHZ) encode members of the R2R3-MYB transcription factor family that regulate anthocyanin synthesis in petunia, and control anthocyanin production in vegetative tissues and contribute to floral pigmentation. In addition to these two MYB factors, the basic helix-loop-helix (bHLH) factor ANTHOCYANIN1 (AN1) and WD-repeat protein AN11, are also essential for vegetative pigmentation. The induction of anthocyanins in vegetative tissues by high light was tightly correlated to the induction of transcripts for PHZ and AN1. Interestingly, transcripts for PhMYB27, a putative R2R3-MYB active repressor, were highly expressed during non-inductive shade conditions and repressed during high light. The competitive inhibitor PhMYBx (R3-MYB) was expressed under high light, which may provide feedback repression. In floral tissues DPL regulates vein-associated anthocyanin pigmentation in the flower tube, while PHZ determines light-induced anthocyanin accumulation on exposed petal surfaces (bud-blush). A model is presented suggesting how complex floral and vegetative pigmentation patterns are derived in petunia in terms of MYB, bHLH and WDR co-regulators.",
"Bulb color is an important consumer trait for onion (Allium cepa L., Allioideae, Asparagales). The bulbs accumulate a range of flavonoid compounds, including anthocyanins (red), flavonols (pale yellow), and chalcones (bright yellow). Flavonoid regulation is poorly characterized in onion and in other plants belonging to the Asparagales, despite being a major plant order containing many important crop and ornamental species. R2R3-MYB transcription factors associated with the regulation of distinct branches of the flavonoid pathway were isolated from onion. These belonged to sub-groups (SGs) that commonly activate anthocyanin (SG6, MYB1) or flavonol (SG7, MYB29) production, or repress phenylpropanoid/flavonoid synthesis (SG4, MYB4, MYB5). MYB1 was demonstrated to be a positive regulator of anthocyanin biosynthesis by the induction of anthocyanin production in onion tissue when transiently overexpressed and by reduction of pigmentation when transiently repressed via RNAi. Furthermore, ectopic red pigmentation was observed in garlic (Allium sativum L.) plants stably transformed with a construct for co-overexpression of MYB1 and a bHLH partner. MYB1 also was able to complement the acyanic petal phenotype of a defined R2R3-MYB anthocyanin mutant in Antirrhinum majus of the asterid clade of eudicots. The availability of sequence information for flavonoid-related MYBs from onion enabled phylogenetic groupings to be determined across monocotyledonous and dicotyledonous species, including the identification of characteristic amino acid motifs. This analysis suggests that divergent evolution of the R2R3-MYB family has occurred between Poaceae/Orchidaceae and Allioideae species. The DNA sequences identified will be valuable for future analysis of classical flavonoid genetic loci in Allium crops and will assist the breeding of these important crop species.",
"Highbush blueberry (Vaccinium corymbosum) fruits contain substantial quantities of flavonoids, which are implicated in a wide range of health benefits. Although the flavonoid constituents of ripe blueberries are known, the molecular genetics underlying their biosynthesis, localization, and changes that occur during development have not been investigated. Two expressed sequence tag libraries from ripening blueberry fruit were constructed as a resource for gene identification and quantitative real-time reverse transcription-polymerase chain reaction primer design. Gene expression profiling by quantitative real-time reverse transcription-polymerase chain reaction showed that flavonoid biosynthetic transcript abundance followed a tightly regulated biphasic pattern, and transcript profiles were consistent with the abundance of the three major classes of flavonoids. Proanthocyanidins (PAs) and corresponding biosynthetic transcripts encoding anthocyanidin reductase and leucoanthocyanidin reductase were most concentrated in young fruit and localized predominantly to the inner fruit tissue containing the seeds and placentae. Mean PA polymer length was seven to 8.5 subunits, linked predominantly via B-type linkages, and was relatively constant throughout development. Flavonol accumulation and localization patterns were similar to those of the PAs, and the B-ring hydroxylation pattern of both was correlated with flavonoid-3'-hydroxylase transcript abundance. By contrast, anthocyanins accumulated late in maturation, which coincided with a peak in flavonoid-3-O-glycosyltransferase and flavonoid-3'5'-hydroxylase transcripts. Transcripts of VcMYBPA1, which likely encodes an R2R3-MYB transcriptional regulator of PA synthesis, were prominent in both phases of development. Furthermore, the initiation of ripening was accompanied by a substantial rise in abscisic acid, a growth regulator that may be an important component of the ripening process and contribute to the regulation of blueberry flavonoid biosynthesis.",
"The ANTHOCYANINLESS2 (ANL2) gene was isolated from Arabidopsis by using the maize Enhancer-Inhibitor transposon tagging system. Sequencing of the ANL2 gene showed that it encodes a homeodomain protein belonging to the HD-GLABRA2 group. As we report here, this homeobox gene is involved in the accumulation of anthocyanin and in root development. Histological observations of the anl2 mutant revealed that the accumulation of anthocyanin was greatly suppressed in subepidermal cells but only slightly reduced in epidermal cells. Furthermore, the primary roots of the anl2 mutant showed an aberrant cellular organization. We discuss a possible role of ANL2 in the accumulation of anthocyanin and cellular organization of the primary root.",
"Massively parallel sequencing of cDNA has enabled deep and efficient probing of transcriptomes. Current approaches for transcript reconstruction from such data often rely on aligning reads to a reference genome, and are thus unsuitable for samples with a partial or missing reference genome. Here we present the Trinity method for de novo assembly of full-length transcripts and evaluate it on samples from fission yeast, mouse and whitefly, whose reference genome is not yet available. By efficiently constructing and analyzing sets of de Bruijn graphs, Trinity fully reconstructs a large fraction of transcripts, including alternatively spliced isoforms and transcripts from recently duplicated genes. Compared with other de novo transcriptome assemblers, Trinity recovers more full-length transcripts across a broad range of expression levels, with a sensitivity similar to methods that rely on genome alignments. Our approach provides a unified solution for transcriptome reconstruction in any sample, especially in the absence of a reference genome.",
"Cranberries (Vaccinium macrocarpon Ait.), renowned for their excellent health benefits, are an important berry crop. Here, we performed transcriptome sequencing of one cranberry cultivar, from fruits at two different developmental stages, on the Illumina HiSeq 2000 platform. Our main goals were to identify putative genes for major metabolic pathways of bioactive compounds and compare the expression patterns between white fruit (W) and red fruit (R) in cranberry. In this study, two cDNA libraries of W and R were constructed. Approximately 119 million raw sequencing reads were generated and assembled de novo, yielding 57,331 high quality unigenes with an average length of 739 bp. Using BLASTx, 38,460 unigenes were identified as putative homologs of annotated sequences in public protein databases, including NCBI NR, NT, Swiss-Prot, KEGG, COG and GO. Of these, 21,898 unigenes mapped to 128 KEGG pathways, with the metabolic pathways, secondary metabolites, glycerophospholipid metabolism, ether lipid metabolism, starch and sucrose metabolism, purine metabolism, and pyrimidine metabolism being well represented. Among them, many candidate genes were involved in flavonoid biosynthesis, transport and regulation. Furthermore, digital gene expression (DEG) analysis identified 3,257 unigenes that were differentially expressed between the two fruit developmental stages. In addition, 14,473 simple sequence repeats (SSRs) were detected. Our results present comprehensive gene expression information about the cranberry fruit transcriptome that could facilitate our understanding of the molecular mechanisms of fruit development in cranberries. Although it will be necessary to validate the functions carried out by these genes, these results could be used to improve the quality of breeding programs for the cranberry and related species.",
"The Rosea1, Rosea2, and Venosa genes encode MYB-related transcription factors active in the flowers of Antirrhinum majus. Analysis of mutant phenotypes shows that these genes control the intensity and pattern of magenta anthocyanin pigmentation in flowers. Despite the structural similarity of these regulatory proteins, they influence the expression of target genes encoding the enzymes of anthocyanin biosynthesis with different specificities. Consequently, they are not equivalent biochemically in their activities. Different species of the genus Antirrhinum, native to Spain and Portugal, show striking differences in their patterns and intensities of floral pigmentation. Differences in anthocyanin pigmentation between at least six species are attributable to variations in the activity of the Rosea and Venosa loci. Set in the context of our understanding of the regulation of anthocyanin production in other genera, the activity of MYB-related genes is probably a primary cause of natural variation in anthocyanin pigmentation in plants."
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what is metabolic syndrome
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Metabolic syndrome (MS) is the concurrence of at least three of five medical conditions: obesity, high blood pressure, insulin resistance, high serum triglyceride (TG) and low serum high-density lipoprotein levels. While fibrates are used to treat disorders other than the lowering serum TG, the mechanism by which fibrates decrease MS has not been established.
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"The function of brown adipose tissue is to transfer energy from food into heat; physiologically, both the heat produced and the resulting decrease in metabolic efficiency can be of significance. Both the acute activity of the tissue, i.e., the heat production, and the recruitment process in the tissue (that results in a higher thermogenic capacity) are under the control of norepinephrine released from sympathetic nerves. In thermoregulatory thermogenesis, brown adipose tissue is essential for classical nonshivering thermogenesis (this phenomenon does not exist in the absence of functional brown adipose tissue), as well as for the cold acclimation-recruited norepinephrine-induced thermogenesis. Heat production from brown adipose tissue is activated whenever the organism is in need of extra heat, e.g., postnatally, during entry into a febrile state, and during arousal from hibernation, and the rate of thermogenesis is centrally controlled via a pathway initiated in the hypothalamus. Feeding as such also results in activation of brown adipose tissue; a series of diets, apparently all characterized by being low in protein, result in a leptin-dependent recruitment of the tissue; this metaboloregulatory thermogenesis is also under hypothalamic control. When the tissue is active, high amounts of lipids and glucose are combusted in the tissue. The development of brown adipose tissue with its characteristic protein, uncoupling protein-1 (UCP1), was probably determinative for the evolutionary success of mammals, as its thermogenesis enhances neonatal survival and allows for active life even in cold surroundings.",
"Leptin is a fat-derived hormone that exerts pleiotropic effects on energy balance and neuroendocrine functions. Mice defective in leptin or its receptor [leptin receptor, isoform b (LepRb)] exhibit profound obesity, infertility, and reduced linear growth. Leptin binding to its receptor triggers multiple signaling pathways, including signal transducer and activator of transcription 3 (Stat 3), phosphatidylinositol-3-kinase, and ERK. A considerable amount of effort has been focused on how these signaling pathways mediate diverse leptin functions. Mice containing a mutant LepRb incapable of Stat3 signaling are obese but remain fertile with enhanced linear growth. In contrast, deletion of Stat3 in the whole brain with Nestin-Cre results in infertility and decreased linear growth, in addition to obesity. The additional phenotypes of the Nestin-mediated deletion could reflect Stat3 action in non-LepRb neurons or leptin-independent Stat3 actions in LepRb neurons. To resolve this discrepancy and to gain more insight into the metabolic actions of Stat3, we have generated mice in which Stat3 is disrupted specifically in LepRb neurons after the onset of leptin receptor expression. We show that mutant mice exhibit profound obesity with increased linear growth and normal fertility. In addition, impaired glycemic control in these animals correlates with their degree of obesity. These results demonstrate that Stat3 in LepRb neurons does not regulate linear growth or fertility. These results further suggest that leptin's effects on growth and reproduction are mediated by other signaling pathways, and that Stat3-mediated control of these functions is mediated independently of leptin and LepRb neurons.",
"Phenotypic modifications of vascular smooth muscle cells (VSMCs) contribute to pathological changes in atherosclerosis where modulation of intracellular calcium plays an important role. In this study, three fibrate drugs, namely gemfibrozil (Gem), fenofibric acid (Fa) and bezafibrate (Beza), were revealed to relax thoracic aorta associated with their potency to reduce intracellular calcium ([Ca²⁺]i) in cultured VSMCs. Relaxation effect of Gem, Fa and Beza was assayed on precontracted rat aortic rings. [Ca²⁺]i level in VSMCs following addition of these fibrates was measured by laser scanning confocal microscopy or flow cytometry. Resultantly, three fibrates showed activity for vasodilation with potency order of Gem>Fa>Beza. Sustained potent reduction of [Ca²⁺]i was observed with Gem 50mg/L and mild reduction with Fa 400-600mg/L, while no effect had been detected for Beza under our current system. Thus, the potency of these fibrates to relax aortic rings correlate well with their effect on [Ca²⁺]i reduction, strongly implicating an underlying causal relationship. Considering that Gem potently reduces [Ca²⁺]i in its clinical concentration range, this study suggests an insight to in situ pharmacological effects of anti-atherosclerosis and clinical toxicity risk.",
"STAT3 (signal transducer and activator of transcription 3) is an important transcription factor involved in many biological events, including apoptosis, tumorigenesis, angiogenesis and epithelial-to-mesenchymal transition. However, no direct evidence for a role of STAT3 in 3T3-L1 adipocyte differentiation has been reported. In the present study, we found that rapid activation of STAT3, lasting for more than 48 h, was elicited upon induction of adipogenesis. Both the STAT3-selective inhibitor stattic and the JAK2 (Janus kinase 2)/STAT3-selective inhibitors AG490 and Gö6976 inhibited STAT3 activation, leading to the suppression of adipocyte differentiation. Adipocyte differentiation was also suppressed by STAT3 siRNA (small interfering RNA) or dominant-negative STAT3. Interestingly, the PPARgamma (peroxisome-proliferator-activated receptor gamma) agonist TAZ (troglitazone) abolished the STAT3-inhibitor- and RNAi (RNA interference)-mediated suppression of adipogenesis. However, TAZ treatment had no effect on the stattic- and AG490-mediated down-regulation of STAT3 activation, suggesting that STAT3 regulates adipocyte differentiation through signalling that occurs upstream of PPARgamma. These data indicate that STAT3 functions as a critical factor for adipogenesis via a mechanism involving the PPARgamma activation pathway.",
"Living in an enriched environment with complex physical and social stimulation leads to improved cognitive and metabolic health. In white fat, enrichment induced the upregulation of the brown fat cell fate determining gene Prdm16, brown fat-specific markers, and genes involved in thermogenesis and β-adrenergic signaling. Moreover, pockets of cells with prototypical brown fat morphology and high UCP1 levels were observed in the white fat of enriched mice associated with resistance to diet-induced obesity. Hypothalamic overexpression of BDNF reproduced the enrichment-associated activation of the brown fat gene program and lean phenotype. Inhibition of BDNF signaling by genetic knockout or dominant-negative trkB reversed this phenotype. Our genetic and pharmacologic data suggest a mechanism whereby induction of hypothalamic BDNF expression in response to environmental stimuli leads to selective sympathoneural modulation of white fat to induce \"browning\" and increased energy dissipation.",
"The objective of this study is to characterize the relationship between forkhead box C2 protein (Foxc2) and leptin under adipose inflammatory response. Lipopolysaccharide (LPS)-induced inflammatory model was conducted. Data from wild-type and ob/ob mice were used to compare the alternative role of leptin on Foxc2-mediated inflammation and browning. Transcriptional regulation and protein-protein interaction were analyzed by bioinformatics and proved by chromatin immunoprecipitation and co-immunoprecipitation experiment. Foxc2 and leptin correlated with inflammation and browning of white adipose tissue (WAT) in LPS-treated mice. Moreover, Foxc2-mediated inhibition of inflammation involved downstream activation of leptin signal and promoted WAT browning. We then determined CREB, the potential transcriptional factor of leptin, was required for Foxc2-mediated inflammation in the regulation of WAT browning. Foxc2 alleviated adipocyte inflammation by reducing leptin-mediated Janus-activated kinase 2/signal transducer and activator of transcription 3 (STAT3) pathway. Importantly, STAT3 physically interacted with PRDM16 and formed a complex to promote WAT browning. Exogenous Foxc2 overexpression also ameliorated inflammation and promoted adipose browning in high fat diet (HFD)-induced obese mice. Our results indicated that Foxc2 inhibited inflammation and promoted browning of WAT through positive regulation of leptin signal and the STAT3-PRDM16 complex. These findings identify a new potential means to prevent and treat obese caused metabolic syndrome of mammals."
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Frzb is required for olfactory axon targeting and basement membrane breakdown in Sox10-null mice
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We and others previously showed that in mouse embryos lacking the transcription factor Sox10, olfactory ensheathing cell (OEC) differentiation is disrupted, resulting in defective olfactory axon targeting and fewer gonadotropin-releasing hormone (GnRH) neurons entering the embryonic forebrain. The underlying mechanisms are unclear. Here, we report that OECs in the olfactory nerve layer express Frzb-encoding a secreted Wnt inhibitor with roles in axon targeting and basement membrane breakdown-from embryonic day (E)12.5, when GnRH neurons first enter the forebrain, until E16.5, the latest stage examined. The highest levels of Frzb expression are seen in OECs in the inner olfactory nerve layer, abutting the embryonic olfactory bulb. We find that Sox10 is required for Frzb expression in OECs, suggesting that loss of Frzb could explain the olfactory axon targeting and/or GnRH neuron migration defects seen in Sox10-null mice. At E16.5, Frzb-null embryos show significant reductions in both the volume of the olfactory nerve layer expressing the maturation marker Omp and the number of Omp-positive olfactory receptor neurons in the olfactory epithelium. As Omp upregulation correlates with synapse formation, this suggests that Frzb deletion indeed disrupts olfactory axon targeting. In contrast, GnRH neuron entry into the forebrain is not significantly affected. Hence, loss of Frzb may contribute to the olfactory axon targeting phenotype, but not the GnRH neuron phenotype, of Sox10-null mice. Overall, our results suggest that Frzb secreted from OECs in the olfactory nerve layer is important for olfactory axon targeting.
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[
"The neural crest arises at the border between the neural plate and the adjacent non-neural ectoderm. It has been suggested that both neural and non-neural ectoderm can contribute to the neural crest. Several studies have examined the molecular mechanisms that regulate neural crest induction in neuralized tissues or the neural plate border. Here, using the chick as a model system, we address the molecular mechanisms by which non-neural ectoderm generates neural crest. We report that in response to FGF the non-neural ectoderm can ectopically express several early neural crest markers (Pax7, Msx1, Dlx5, Sox9, FoxD3, Snail2, and Sox10). Importantly this response to FGF signaling can occur without inducing ectopic mesodermal tissues. Furthermore, the non-neural ectoderm responds to FGF by expressing the prospective neural marker Sox3, but it does not express definitive markers of neural or anterior neural (Sox2 and Otx2) tissues. These results suggest that the non-neural ectoderm can launch the neural crest program in the absence of mesoderm, without acquiring definitive neural character. Finally, we report that prior to the upregulation of these neural crest markers, the non-neural ectoderm upregulates both BMP and Wnt molecules in response to FGF. Our results provide the first effort to understand the molecular events leading to neural crest development via the non-neural ectoderm in amniotes and present a distinct response to FGF signaling.",
"Primary olfactory neurons are located in the olfactory neuroepithelium lining the nasal cavity. Their axons converge and form glomeruli with the dendrites of second-order neurons in the olfactory bulb. The molecular basis of primary olfactory axon guidance, targeting and subsequent arborisation is largely unknown. In this study we examined the spatio-temporal expression of the Eph receptor EphB2 and its ligands, ephrin-B1 and ephrin-B2, during development of the rat primary olfactory system. Unlike in other regions of the nervous system where receptor and ligand expression patterns are usually non-overlapping, EphB2, ephrin-B1 and ephrin-B2 were all expressed by primary and second-order olfactory neurons. In the embryonic animal we found that these three proteins had distinct and different expression patterns. EphB2 was first expressed at E18.5 by the perikarya of primary olfactory neurons. In contrast, ephrin-B1 was expressed from E13.5 and was localised to the axons of these cells up to E18.5 but was then restricted to the perikarya. Ephrin-B2, however, was expressed by olfactory ensheathing cells. EphB2, ephrin-B1 and ephrin-B2 were also expressed in the prenatal olfactory bulb and were restricted to the perikarya of mitral cells. In the post-natal olfactory bulb there was a shift in the localisation of both EphB2 and ephrin-B1 to the dendritic arborisations of mitral cells. The dynamic and tightly regulated spatio-temporal expression patterns of EphB2, ephrin-B1 and ephrin-B2 by specific olfactory cell populations suggest that these molecules have the potential to regulate important developmental events in the olfactory system.",
"Axons from olfactory sensory neurons (OSNs) expressing a specific odorant receptor (OR) project to specific subsets of glomeruli in the olfactory bulb (for review, see Mombaerts, 1999, 2001). The aim of this study was to examine the trajectories that subsets of axons from OSNs expressing the same OR follow within the olfactory nerve and olfactory nerve layer (ONL) of adult mice. Using confocal microscopy, we generated serial reconstructions of axons from M72-IRES-tauGFP-expressing OSNs as they coursed within the ONL and into glomeruli. GFP-expressing axons were loosely aggregated in the outer ONL; however, as they entered the inner ONL, the majority fasciculated with other GFP-expressing axons before entering the glomerular neuropil. Although the vast majority of axons entered the glomerulus from the directly apposed ONL, some followed tortuous courses through and/or around adjacent glomeruli before terminating in the target glomerulus. Similar observations were made on subpopulations of axons in M71-IRES-tauGFP and P2-IRES-tauGFP mice. Ultrastructural analyses of labeled M72 glomeruli showed no evidence of axodendritic synapses other than those with GFP-labeled axon terminals. These data are consistent with the notion that OSN axons are highly precise in targeting glomeruli and that glomeruli, in turn, are highly homogeneous with regard to the OR expressed by the innervating OSNs. Because some single axons could follow idiosyncratic trajectories to the target glomerulus, it appears that stable homotypic fasciculation is not a prerequisite for correct targeting.",
"The human nose is often considered something of a luxury, but in the rest of the animal world, from bacteria to mammals, detecting chemicals in the environment has been critical to the successful organism. An indication of the importance of olfactory systems is the significant proportion - as much as 4% - of the genomes of many higher eukaryotes that is devoted to encoding the proteins of smell. Growing interest in the detection of diverse compounds at single-molecule levels has made the olfactory system an important system for biological modelling.",
"Olfactory ensheathing cells (OECs) are a unique class of glial cells with exceptional translational potential because of their ability to support axon regeneration in the central nervous system. Although OECs are similar in many ways to immature and nonmyelinating Schwann cells, and can myelinate large-diameter axons indistinguishably from myelination by Schwann cells, current dogma holds that OECs arise from the olfactory epithelium. Here, using fate-mapping techniques in chicken embryos and genetic lineage tracing in mice, we show that OECs in fact originate from the neural crest and hence share a common developmental heritage with Schwann cells. This explains the similarities between OECs and Schwann cells and overturns the existing dogma on the developmental origin of OECs. Because neural crest stem cells persist in adult tissue, including skin and hair follicles, our results also raise the possibility that patient-derived neural crest stem cells could in the future provide an abundant and accessible source of autologous OECs for cell transplantation therapy for the injured central nervous system.",
"Olfactory sensory neurons (OSNs) expressing a given odorant receptor (OR) gene project their axons to a few specific glomeruli that reside at recognizable locations in the olfactory bulb. Connecting approximately 1000 populations of OSNs to the approximately 1800 glomeruli of the mouse bulb poses a formidable wiring problem. Additional progress in understanding the mechanisms of neuronal connectivity is dependent on knowing how these axonal pathways are organized and how they form during development. Here we have applied a genetic approach to this problem. We have constructed by gene targeting novel strains of mice in which either all OSNs or those that express a specific OR gene, M72 or M71, also produce green fluorescent protein (GFP) or a fusion of tau with GFP. We visualized OSNs and their axons in whole mounts with two-photon laser scanning microscopy. The main conclusion we draw from the three-dimensional reconstructions is the high degree of morphological variability of mature glomeruli receiving axonal input from OR-expressing OSNs and of the pathways taken by the axons to those glomeruli. We also observe that axons of OR-expressing OSNs do not innervate nearby glomeruli in mature mice. Postnatally, a tangle of axons from M72-expressing OSNs occupies a large surface area of the bulb and coalesces abruptly into a protoglomerulus at a reproducible stage of development. These results differ in several aspects from those reported for the development of glomeruli receiving input from OSNs expressing the P2 OR, suggesting the need for a more systematic examination of OR-specific glomeruli.",
"Psychophysical studies indicate that structural features of odorants differentially influence their perceived odor. In the olfactory bulb (OB), odorants are represented by ensembles of activated glomeruli. Here we used optical imaging of intrinsic signals to examine how these structural features are represented spatially in the sensory map of the rat OB. We found that the dorsal OB contained two topographically fixed domains; constituent glomeruli in each domain could be activated by odorants with particular functional groups. Within each domain, other structural features such as carbon chain length and branching were represented by local differences in patterns. These results suggest that structural features are categorized into two classes, primary features (functional groups) that characterize each domain, and secondary features that are represented by local positions within each domain. Such hierarchical representations of different structural features correlate well with psychophysical structure-odor relationships."
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Microtubule organization in axons and dendrites
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The specific organization of the neuronal microtubule cytoskeleton in axons and dendrites is an evolutionarily conserved determinant of neuronal polarity that allows for selective cargo sorting. However, how dendritic microtubules are organized and whether local differences influence cargo transport remains largely unknown. Here, we use live-cell imaging to systematically probe the microtubule organization in
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"In Chinese hamster ovary cells, microtubules originate at the microtubule organizing center (MTOC) and grow persistently toward the cell edge, where they undergo catastrophe. In axons, microtubule dynamics must be regulated differently because microtubules grow parallel to the plasma membrane and there is no MTOC. GFP-tagged microtubule plus end tracking proteins (+TIPs) mark the ends of growing neuronal microtubules. Their fluorescent \"comet-like\" pattern reflects turnover of +TIP binding sites. Using GFP-tagged +TIPs and fluorescence-based segmentation and tracking tools, we show that axonal microtubules grow with a constant average velocity and that they undergo catastrophes at random positions, yet in a programmed fashion. Using protein depletion approaches, we find that the +TIPs CLIP-115 and CLIP-170 affect average microtubule growth rate and growth distance in neurons but not the duration of a microtubule growth event. In N1E-115 neuroblastoma cells, we find that EB1, the core +TIP, regulates microtubule growth rate, growth distance, and duration, consistent with in vitro data. Combined, our data suggest that CLIPs influence the axonal microtubule/tubulin ratio, whereas EB1 stimulates microtubule growth and structural transitions at microtubule ends, thereby regulating microtubule catastrophes and the turnover of +TIP binding sites.",
"Long-range retrograde axonal transport in neurons is driven exclusively by the microtubule motor cytoplasmic dynein. The efficient initiation of dynein-mediated transport from the distal axon is critical for normal neuronal function, and neurodegenerative disease-associated mutations have been shown to specifically disrupt this process. Here, we examine the role of dynamic microtubules and microtubule plus-end binding proteins (+TIPs) in the initiation of dynein-mediated retrograde axonal transport using live-cell imaging of cargo motility in primary mouse dorsal root ganglion neurons. We show that end-binding (EB)-positive dynamic microtubules are enriched in the distal axon. The +TIPs EB1, EB3, and cytoplasmic linker protein-170 (CLIP-170) interact with these dynamic microtubules, recruiting the dynein activator dynactin in an ordered pathway, leading to the initiation of retrograde transport by the motor dynein. Once transport has initiated, however, neither the EBs nor CLIP-170 are required to maintain transport flux along the mid-axon. In contrast, the +TIP Lis1 activates transport through a distinct mechanism and is required to maintain processive organelle transport along both the distal and mid-axon. Further, we show that the EB/CLIP-170/dynactin-dependent mechanism is required for the efficient initiation of transport from the distal axon for multiple distinct cargos, including mitochondria, Rab5-positive early endosomes, late endosomes/lysosomes, and TrkA-, TrkB-, and APP-positive organelles. Our observations indicate that there is an essential role for +TIPs in the regulation of retrograde transport initiation in the neuron.",
"Axonal microtubules are predominantly organized into a plus-end-out pattern. Here, we tested both experimentally and with computational modeling whether a motor-based polarity-sorting mechanism can explain this microtubule pattern. The posited mechanism centers on cytoplasmic dynein transporting plus-end-out and minus-end-out microtubules into and out of the axon, respectively. When cytoplasmic dynein was acutely inhibited, the bi-directional transport of microtubules in the axon was disrupted in both directions, after which minus-end-out microtubules accumulated in the axon over time. Computational modeling revealed that dynein-mediated transport of microtubules can establish and preserve a predominantly plus-end-out microtubule pattern as per the details of the experimental findings, but only if a kinesin motor and a static cross-linker protein are also at play. Consistent with the predictions of the model, partial depletion of TRIM46, a protein that cross-links axonal microtubules in a manner that influences their polarity orientation, leads to an increase in microtubule transport.",
"In neurons, microtubules (MTs) span the length of both axons and dendrites, and the molecular motors use these intracellular 'highways' to transport diverse cargo to the appropriate subcellular locations. Whereas axonal MTs are organized such that the plus-end is oriented out from the cell body, dendrites exhibit a mixed MTs polarity containing both minus-end-out and plus-end-out MTs. The molecular mechanisms underlying this differential organization, as well as its functional significance, are unknown. Here, we show that kinesin-1 is critical in establishing the characteristic minus-end-out MT organization of the dendrite in vivo. In unc-116 (kinesin-1/kinesin heavy chain) mutants, the dendritic MTs adopt an axonal-like plus-end-out organization. Kinesin-1 protein is able to cross-link anti-paralleled MTs in vitro. We propose that kinesin-1 regulates the dendrite MT polarity through directly gliding the plus-end-out MTs out of the dendrite using both the motor domain and the C-terminal MT-binding domain. DOI:http://dx.doi.org/10.7554/eLife.00133.001.",
"Vigorous transport of cytoplasmic components along axons over substantial distances is crucial for the maintenance of neuron structure and function. The transport of mitochondria, which serves to distribute mitochondrial functions in a dynamic and non-uniform fashion, has attracted special interest in recent years following the discovery of functional connections among microtubules, motor proteins and mitochondria, and their influences on neurodegenerative diseases. Although the motor proteins that drive mitochondrial movement are now well characterized, the mechanisms by which anterograde and retrograde movement are coordinated with one another and with stationary axonal mitochondria are not yet understood. In this Commentary, we review why mitochondria move and how they move, focusing particularly on recent studies of transport regulation, which implicate control of motor activity by specific cell-signaling pathways, regulation of motor access to transport tracks and static microtubule-mitochondrion linkers. A detailed mechanism for modulating anterograde mitochondrial transport has been identified that involves Miro, a mitochondrial Ca(2+)-binding GTPase, which with associated proteins, can bind and control kinesin-1. Elements of the Miro complex also have important roles in mitochondrial fission-fusion dynamics, highlighting questions about the interdependence of biogenesis, transport, dynamics, maintenance and degradation.",
"In neurons, the distinct molecular composition of axons and dendrites is established through polarized targeting mechanisms, but it is currently unclear how nonpolarized cargoes, such as mitochondria, become uniformly distributed over these specialized neuronal compartments. Here, we show that TRAK family adaptor proteins, TRAK1 and TRAK2, which link mitochondria to microtubule-based motors, are required for axonal and dendritic mitochondrial motility and utilize different transport machineries to steer mitochondria into axons and dendrites. TRAK1 binds to both kinesin-1 and dynein/dynactin, is prominently localized in axons, and is needed for normal axon outgrowth, whereas TRAK2 predominantly interacts with dynein/dynactin, is more abundantly present in dendrites, and is required for dendritic development. These functional differences follow from their distinct conformations: TRAK2 preferentially adopts a head-to-tail interaction, which interferes with kinesin-1 binding and axonal transport. Our study demonstrates how the molecular interplay between bidirectional adaptor proteins and distinct microtubule-based motors drives polarized mitochondrial transport.",
"Several microtubule-binding proteins including EB1, dynactin, APC, and CLIP-170 localize to the plus-ends of growing microtubules. Although these proteins can bind to microtubules independently, evidence for interactions among them has led to the hypothesis of a plus-end complex. Here we clarify the interaction between EB1 and dynactin and show that EB1 binds directly to the N-terminus of the p150(Glued) subunit. One function of a plus-end complex may be to regulate microtubule dynamics. Overexpression of either EB1 or p150(Glued) in cultured cells bundles microtubules, suggesting that each may enhance microtubule stability. The morphology of these bundles, however, differs dramatically, indicating that EB1 and dynactin may act in different ways. Disruption of the dynactin complex augments the bundling effect of EB1, suggesting that dynactin may regulate the effect of EB1 on microtubules. In vitro assays were performed to elucidate the effects of EB1 and p150(Glued) on microtubule polymerization, and they show that p150(Glued) has a potent microtubule nucleation effect, whereas EB1 has a potent elongation effect. Overall microtubule dynamics may result from a balance between the individual effects of plus-end proteins. Differences in the expression and regulation of plus-end proteins in different cell types may underlie previously noted differences in microtubule dynamics."
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Retinoic acid and histone deacetylase inhibitors induce microRNA-22 induction to epigenetically regulate itself and nerve growth factor IB
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This study investigates the mechanism and consequences of microRNA-22 ( miR-22) induction. Our data revealed for the first time that retinoic acid (RA) and histone deacetylase (HDAC) inhibitors, including short-chain fatty acids and suberanilohydroxamic acid (SAHA), could individually or in combination induce miR-22. This induction was mediated via RA receptor β (RARβ) binding to a direct repeat 5 (DR5) motif. In addition, we uncovered HDAC1 as a novel miR-22 target. In an miR-22-dependent manner, HDAC inhibitors and RA reduced HDAC1, HDAC4, and sirtuin 1 (SIRT1), which were involved in chromatin remodeling of the RARβ and nerve growth factor IB ( NUR77). Thus, HDAC inhibitors and RA-induced miR-22 resulted in simultaneous induction of cytoplasmic RARβ and NUR77, leading to apoptosis of colon cancer cells. In mice, miR-22 and its inducers inhibited the growth of xenograft colon cancer. Moreover, tumor size reduction was accompanied by elevated miR-22, NUR77, and RARβ and by reduced HDACs. In human colon polyps and adenocarcinomas, miR-22 and RARβ were consistently reduced, which was associated with elevated HDAC1, HDAC4, and SIRT1 in colon adenocarcinomas. Results from this study revealed a novel anticancer mechanism of RARβ via miR-22 induction to epigenetically regulate itself and NUR77, providing a promising cancer treatment modality using miR-22 and its inducers.-Hu, Y., French, S. W., Chau, T., Liu, H.-X., Sheng, L., Wei, F., Stondell, J., Garcia, J. C., Du, Y., Bowlus, C. L., Wan, Y.-J. Y. RARβ acts as both an upstream regulator and downstream effector of miR-22, which epigenetically regulates NUR77 to induce apoptosis of colon cancer cells.
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[
"Bile acids (BA) are endogenous agents capable of causing cancer throughout the gastrointestinal (GI) tract. To uncover the mechanism by which BAs exert carcinogenic effects, both human liver and colon cancer cells as well as mouse primary hepatocytes were treated with BAs and assayed for viability, genotoxic stress, and transcriptional response. BAs induced both Nur77 (NR4A1) and proinflammatory gene expression. The intracellular location of BA-induced Nur77 was time dependent; short-term (1-3 hours) exposure induced nuclear Nur77, whereas longer (1-2 days) exposure also increased cytosolic Nur77 expression and apoptosis. Inhibiting Nur77 nuclear export with leptomycin B decreased lithocholic acid (LCA)-induced apoptosis. Extended (7 days) treatment with BA generated resistance to BA with increased nuclear Nur77, viability, and mobility. While, knockdown of Nur77 in BA-resistant cells increased cellular susceptibility to LCA-induced apoptosis. Moreover, in vivo mouse xenograft experiments demonstrated that BA-resistant cells form larger tumors with elevated Nur77 expression compared with parental controls. DNA-binding and gene expression assays identified multiple survival genes (CDK4, CCND2, MAP4K5, STAT5A, and RBBP8) and a proapoptosis gene (BID) as Nur77 targets. Consistently, BA-induced upregulation of the aforementioned genes was abrogated by a lack of Nur77. Importantly, Nur77 was overexpressed in high percentage of human colon and liver cancer specimens, and the intracellular location of Nur77 correlated with elevated serum total BA levels in patients with colon cancer. These data show for the first time that BAs via Nur77 have a dual role in modulating cell survival and death. These findings establish a direct link between Nur77 and the carcinogenic effect of BAs.",
"Retinoids are ubiquitous signaling molecules that influence nearly every cell type, exert profound effects on development, and complement cancer chemotherapeutic regimens. All-trans retinoic acid (RA) and other active retinoids are generated from vitamin A (retinol), but key aspects of the signaling pathways required to produce active retinoids remain unclear. Retinoids generated by one cell type can affect nearby cells, so retinoids also function in intercellular communication. RA induces differentiation primarily by binding to RARs, transcription factors that associate with RXRs and bind RAREs in the nucleus. Binding of RA: (1) initiates changes in interactions of RAR/RXRs with co-repressor and co-activator proteins, activating transcription of primary target genes; (2) alters interactions with proteins that induce epigenetic changes; (3) induces transcription of genes encoding transcription factors and signaling proteins that further modify gene expression (e.g., FOX03A, Hoxa1, Sox9, TRAIL, UBE2D3); and (4) results in alterations in estrogen receptor α signaling. Proteins that bind at or near RAREs include Sin3a, N-CoR1, PRAME, Trim24, NRIP1, Ajuba, Zfp423, and MN1/TEL. Interactions among retinoids, RARs/RXRs, and these proteins explain in part the powerful effects of retinoids on stem cell differentiation. Studies of this retinol signaling cascade enhance our ability to understand and regulate stem cell differentiation for therapeutic and scientific purposes. In cancer chemotherapeutic regimens retinoids can promote tumor cell differentiation and/or induce proteins that sensitize tumors to drug combinations. Mechanistic studies of retinoid signaling continue to suggest novel drug targets and will improve therapeutic strategies for cancer and other diseases, such as immune-mediated inflammatory diseases.",
"Retinoic acid (RA) has diverse biological effects. The liver stores vitamin A, generates RA, and expresses receptors for RA. The current study examines the hepatic binding profile of two RA receptor isoforms, RARA (RARα) and RARB (RARβ), in response to RA treatment in mouse livers. Our data uncovered 35,521, and 14,968 genomic bindings for RARA and RARB, respectively. Each expressed unique and common bindings, implying their redundant and specific roles. RARB has higher RA responsiveness than RARB. RA treatment generated 18,821 novel RARB bindings but only 14,798 of RARA bindings, compared with the control group. RAR frequently bound the consensus hormone response element [HRE; (A/G)G(G/T)TCA], which often contained the motifs assigned to SP1, GABPA, and FOXA2, suggesting potential interactions between those transcriptional factors. Functional annotation coupled with principle component analysis revealed that the function of RAR target genes were motif dependent. Taken together, the cistrome of RARA and RARB revealed their extensive biological roles in the mouse liver. RAR target genes are enriched in various biological processes. The hepatic RAR genome-wide binding data can help us understand the global molecular mechanisms underlying RAR and RA-mediated gene and pathway regulation.",
"The pregnane X receptor (PXR) is a key regulator of xenobiotic metabolism and disposition in liver. However, little is known about the PXR DNA-binding signatures in vivo, or how PXR regulates novel direct targets on a genome-wide scale. Therefore, we generated a roadmap of hepatic PXR bindings in the entire mouse genome [chromatin immunoprecipitation (ChIP)-Seq]. The most frequent PXR DNA-binding motif is the AGTTCA-like direct repeat with a 4 bp spacer [direct repeat (DR)-4)]. Surprisingly, there are also high motif occurrences with spacers of a periodicity of 5 bp, forming a novel DR-(5 n+4) pattern for PXR binding. PXR-binding overlaps with the epigenetic mark for gene activation (histone-H3K4-di-methylation), but not with epigenetic marks for gene suppression (DNA methylation or histone-H3K27-tri-methylation) (ChIP-on-chip). After administering a PXR agonist, changes in mRNA of most PXR-direct target genes correlate with increased PXR binding. Specifically, increased PXR binding triggers the trans-activation of critical drug-metabolizing enzymes and transporters. The mRNA induction of these genes is absent in PXR-null mice. The current work provides the first in vivo evidence of PXR DNA-binding signatures in the mouse genome, paving the path for predicting and further understanding the multifaceted roles of PXR in liver.",
"Over the last 25 years roles have been established for vitamin D receptor (VDR) in influencing cell proliferation and differentiation. For example, murine knock-out approaches have revealed a role for the VDR in controlling mammary gland growth and function. These actions appear widespread, as the enzymes responsible for 1alpha,25-dihydroxycholecalciferol generation and degradation, and the VDR itself, are all functionally present in a wide range of epithelial and haematopoietic cell types. These findings, combined with epidemiological and functional data, support the concept that local, autocrine and paracrine VDR signalling exerts control over cell-fate decisions in multiple cell types. Furthermore, the recent identification of bile acid lithocholic acid as a VDR ligand underscores the environmental sensing role for the VDR. In vitro and in vivo dissection of VDR signalling in cancers (e.g. breast, prostate and colon) supports a role for targeting the VDR in either chemoprevention or chemotherapy settings. As with other potential therapeutics, it has become clear that cancer cells display de novo and acquired genetic and epigenetic mechanisms of resistance to these actions. Consequently, a range of experimental and clinical options are being developed to bring about more targeted actions, overcome resistance and enhance the efficacy of VDR-centred therapeutics.",
"Modulation of Sp1 activity by nuclear receptors is a novel mechanism by which fat-soluble hormones regulate gene expression. We previously established that upon autoinduction of RARs by RA, RARs/RXRs physically interact with Sp1, potentiate Sp1 binding to the GC box motifs, and thus enhance transactivation of the urokinase promoter, which lacks a canonical RAR-responsive element/RXR-responsive element. Here, we examined whether a similar mechanism might participate in transcriptional regulation of other key RA-inducible genes in endothelial cells and characterized binding between Sp1 and GC box motifs. Northern blot analyses showed that in addition to urokinase, after induction of RARs, RA up-regulates GC-rich region-dependent mRNA expression of transglutaminase, TGF beta 1, and types I and II TGF beta receptors. RA failed to alter the expression of Sp1 at both mRNA and protein levels. Reporter and gel shift assays and Western blot analyses suggested that either RA-treatment or RAR/RXR-overexpression enhances transactivation of these genes through a GC-rich region and strengthens the affinity of Sp1 to GC box motifs, accompanying a potential conformational change of Sp1 as reflected in its increased immunogenicity. Detailed analyses of the GC box motifs within the urokinase and other promoters indicate that interaction between RAR/RXR and Sp1 does not occur in the presence of nonfunctional GC box motifs containing five tandem purine or pyrimidine bases at the 3'-flanking region of hexanucleotide core sequence. These findings provide insight into the molecular mechanisms underlying RARE/RXRE-independent transactivation of RA-inducible gene promoters.",
"The eyes and skin are obvious retinoid target organs. Vitamin A deficiency causes night blindness and retinoids are widely used to treat acne and psoriasis. However, more than 90% of total body retinol is stored in liver stellate cells. In addition, hepatocytes produce the largest amount of retinol binding protein and cellular retinoic acid binding protein to mobilize retinol from the hepatic storage pool and deliver retinol to its receptors, respectively. Furthermore, hepatocytes express the highest amount of retinoid x receptor alpha (RXRα) among all the cell types. Surprisingly, the function of endogenous retinoids in the liver has received very little attention. Based on the data generated from chromatin immunoprecipitation followed by sequencing, the global DNA binding of transcription factors including retinoid x receptor α (RXRα) along with its partners i.e. retinoic acid receptor α (RARα), pregnane x receptor (PXR), liver x receptor (LXR), farnesoid x receptor (FXR), and peroxisome proliferator-activated receptor α (PPARα) has been established. Based on the binding, functional annotation illustrated the role of those receptors in regulating hepatic lipid homeostasis. To correlate the DNA binding data with gene expression data, the expression patterns of 576 genes that regulate lipid homeostasis were studied in wild type and liver RXRα-null mice treated with and without RA. The data showed that RA treatment and RXRα-deficiency had opposite effects in regulating lipid homeostasis. A subset of genes (114), which could clearly differentiate the effect of ligand treatment and receptor deficiency, were selected for further functional analysis. The expression data suggested that RA treatment could produce unsaturated fatty acids and induce triglyceride breakdown, bile acid secretion, lipolysis, and retinoids elimination. In contrast, RXRα deficiency might induce the synthesis of saturated fatty acids, triglyceride, cholesterol, bile acids, and retinoids. In addition, DNA binding data indicated extensive cross-talk among RARα, PXR, LXR, FXR, and PPARα in regulating those RA/RXRα-dependent gene expression levels. Moreover, RA reduced serum cholesterol, triglyceride, and bile acid levels in mice. We have characterized the role of hepatic RA for the first time. Hepatic RA mediated through RXRα and its partners regulates lipid homeostasis."
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Thrombelastograph and platelet labeling in the ovine model.
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Ovines are a common animal model for the study of cardiovascular devices, where consideration of blood biocompatibility is an essential design criterion. In the ovine model, tools to assess blood biocompatibility are limited and continued investigation to identify and apply additional assays is merited. Toward this end, the thrombelastograph, clinically utilized to assess hemostasis, was used to characterize normal ovine parameters. In addition, platelet labeling with biotin was evaluated for its potential applicability to quantify ovine platelet life span. Mean ovine thrombelastograph values were reaction-time: 4.9 min, K-time: 2 min, angle: 64.1°, maximum amplitude: 68.6mm, actual clot strength: 11.9 kd/s, and coagulation index: 1.5. Reaction time was significantly shorter and maximum amplitude, actual clot strength, and coagulation index were all significantly higher when compared to normal human thrombelastograph values suggesting some hypercoagulability of sheep blood. Biotinylation and reinfusion of ovine platelets allowed temporal tracking of the labeled platelet cohort with flow cytometry. These data indicated a mean ovine platelet life span of 188h with a half-life of 84h. The collection of these parameters for normal ovines demonstrates the applicability of these techniques for subsequent studies where cardiovascular devices may be evaluated and provides an indication of normal ovine values for comparison purposes.
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[
"To determine if thromboelastography (TEG) is predictive of patient outcomes following traumatic injury. A retrospective review of 131 patients with pelvic trauma admitted to a Level II trauma center was conducted over four years from 1 January 2009 to 31 December 2012. Patients were identified retrospectively from a prospectively collected database of acute pelvic trauma (n = 372). Eligible patients were identified from billing/coding data as having fractures of the acetabulum, iliac wing or sacral alae. Patients with incomplete TEG data were excluded (n = 241), as were patients with pathological fractures. TEG clotting variables and traditional clotting variables were recorded. Evaluation of TEG data revealed 41 patients with abnormal clotting times (TEG R). TEG R > 6 was an independent risk factor for death (OR, 16; 95%CI 5.4-53; P = 0.0001). The death rate was 52% in patients with TEG R values ≥6 (n = 13/25). There was no significant association between traditional clotting markers and death rate. TEG reaction time value, representing the time of initial clot formation, was the only hematologic marker predictive of mortality in patients with pelvic trauma. Delay in reaction time was associated with a significantly increased death rate, independent of injury severity. The death rate association was not observed with traditional markers of clotting. Future prospective studies may be warranted to determine the presentation and significance of TEG abnormalities when resuscitating patients with orthopaedic trauma.",
"Platelets are derived from the cytoplasm of mature marrow megakaryocytes through cytoplasmic demarcation by invaginating plasma membrane and fragmentation of cytoplasmic protrusions into marrow sinusoids. Thereafter, platelets survive in the circulation for about 9 to 10 days. Platelet production is regulated to meet the demands for circulating platelets by means of humoral stimulation. Mean platelet volume, about 10 fl, remains constant over a wide range of survival times and production rates. In normal individuals platelets are produced at a rate of 35 X 10(9)/1/day (or 2.5 X 10(10) fl/kg body wt.) and reflect directly the marrow megakaryocyte cytoplasmic mass. Platelets have important roles in haemostasis, arterial thrombogenesis, wound healing and atherogenesis. Measurements of platelet survival are useful as an in vivo indicator of platelet participation in pathogenesis and pharmacological prevention of these processes. At present platelet survival is most reliably determined by in vitro radiochromium population labelling. 51Cr-platelet disappearance curves require objective unbiased analysis, preferably by non-linear gamma function least squares computer fitting procedures.",
"The Levitronix PediVAS is an extracorporeal magnetically levitated pediatric ventricular assist system with an optimal flow rate range of 0.3-1.5 L/min. The system is being tested in preclinical studies to assess hemodynamic performance and biocompatibility. The PediVAS was implanted in nine ovines for 30 days using either commercially available cannulae (n = 3) or customized Levitronix cannulae (n = 6). Blood biocompatibility in terms of circulating activated platelets was measured by flow cytometric assays to detect P-selectin. Platelet activation was further examined after exogenous agonist stimulation. Platelet activation increased after surgery and eventually returned to baseline in animal studies where minimal kidney infarcts were observed. Platelet activation remained elevated for the duration of the study in animals where a moderate number of kidney infarcts with or without thrombotic deposition in the cannulae were observed. When platelet activation did return to baseline, platelets appropriately responded to agonist stimulation, signifying conserved platelet function after PediVAS implant. Platelet activation returned to baseline in the majority of studies, representing a promising biocompatibility result for the Levitronix PediVAS.",
"The thromboresistance of 13 potentially blood-compatible polymers was assessed in sheep by determining survival of 51Cr-labeled platelets. Polymer tubing (120-150 cm x 2.0-2.3 mm i.d.) coiled around the neck was incorporated into the circulation through silicone rubber connectors as a carotid artery-external jugular vein shunt. The mean platelet half-life in control animals (\"shunt control\") was 78.2 +/- 2.8 (SEM) hours. Eleven of the 13 polymers tested significantly shortened platelet half-life. Polyvinyl chloride (T1/2 = 45.4 +/- 3.0 hours), polyperfluoro ethylene (T1/2 = 47.0 +/-1.6 hours), and a polymethylacrylate (PMA)/acrilonitrile copolymer (T1/2 = 50.7 +/- 7.0 hours) produced the greatest shortening. Only silica-free polydimethyl siloxane (T1/2 = 74.7 +/- 4.9 hours) and PMA (T1/2 = 81.5 +/- 3.4 hours) were indistinguishable from shunt controls. Pretreatment of PMA tubing with autologous plasma in a paired trial significantly increased platelet half-life (P less than 0.05 vs. untreated PMA). This system offers an economical, reproducible, sensitive, and biologically relevant method for assessment of the reactivity of artificial surfaces with platelets.",
"Despite the many advances in the management of patients with acute heart failure, the outcome for patients with refractory acute cardiogenic shock remains disproportionately poor. Clearly, there is a definitive role for wider application of temporary circulatory support in such patients. Questions remain as to the ideal device, the optimal duration of temporary support, and the ideal timing to bridge these patients to a long-term device. There are currently several options available for circulatory support and include surgically implanted ventricular assist devices, percutaneous assist devices, and extracorporeal membrane oxygenation. This review includes a brief summary of the current assist devices available along with the University of Minnesota's experience with the Levitronix CentriMag system."
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Stability of RNA polymerases backtracking by one nucleotide
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All cellular RNA polymerases (RNAP) occasionally backtrack along the template DNA as part of transcriptional proofreading and regulation. Here, we studied the mechanism of RNAP backtracking by one nucleotide using two complementary approaches that allowed us to precisely measure the occupancy and lifetime of the backtracked state. Our data show that the stability of the backtracked state is critically dependent on the closure of the RNAP active site by a mobile domain, the trigger loop (TL). The lifetime and occupancy of the backtracked state measurably decreased by substitutions of the TL residues that interact with the nucleoside triphosphate (NTP) substrate, whereas amino acid substitutions that stabilized the closed active site increased the lifetime and occupancy. These results suggest that the same conformer of the TL closes the active site during catalysis of nucleotide incorporation into the nascent RNA and backtracking by one nucleotide. In support of this hypothesis, we construct a model of the 1-nt backtracked complex with the closed active site and the backtracked nucleotide in the entry pore area known as the E-site. We further propose that 1-nt backtracking mimics the reversal of the NTP substrate loading into the RNAP active site during on-pathway elongation.
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[
"Polymerases form a class of enzymes that act as molecular motors as they move along their nucleic acid substrate during catalysis, incorporating nucleotide triphosphates at the end of the growing chain and consuming chemical energy. A debated issue is how the enzyme converts chemical energy into motion [J. Gelles and R. Landick, Cell 93, 13 (1998)]. In a single molecule assay, we studied how an opposing mechanical force affects the translocation rate of T7 RNA polymerase. Our measurements show that force acts as a competitive inhibitor of nucleotide binding. This result is interpreted in the context of possible models, and with respect to published crystal structures of T7 RNA polymerase. The transcribing complex appears to utilize only a small fraction of the energy of hydrolysis to perform mechanical work, with the remainder being converted to heat.",
"During gene transcription, RNA polymerase (Pol) II moves forwards along DNA and synthesizes messenger RNA. However, at certain DNA sequences, Pol II moves backwards, and such backtracking can arrest transcription. Arrested Pol II is reactivated by transcription factor IIS (TFIIS), which induces RNA cleavage that is required for cell viability. Pol II arrest and reactivation are involved in transcription through nucleosomes and in promoter-proximal gene regulation. Here we present X-ray structures at 3.3 Å resolution of an arrested Saccharomyces cerevisiae Pol II complex with DNA and RNA, and of a reactivation intermediate that additionally contains TFIIS. In the arrested complex, eight nucleotides of backtracked RNA bind a conserved 'backtrack site' in the Pol II pore and funnel, trapping the active centre trigger loop and inhibiting mRNA elongation. In the reactivation intermediate, TFIIS locks the trigger loop away from backtracked RNA, displaces RNA from the backtrack site, and complements the polymerase active site with a basic and two acidic residues that may catalyse proton transfers during RNA cleavage. The active site is demarcated from the backtrack site by a 'gating tyrosine' residue that probably delimits backtracking. These results establish the structural basis of Pol II backtracking, arrest and reactivation, and provide a framework for analysing gene regulation during transcription elongation.",
"Binding of a ribonucleoside triphosphate to an RNA polymerase II transcribing complex, with base pairing to the template DNA, was revealed by X-ray crystallography. Binding of a mismatched nucleoside triphosphate was also detected, but in an adjacent site, inverted with respect to the correctly paired nucleotide. The results are consistent with a two-step mechanism of nucleotide selection, with initial binding to an entry (E) site beneath the active center in an inverted orientation, followed by rotation into the nucleotide addition (A) site for pairing with the template DNA. This mechanism is unrelated to that of single subunit RNA polymerases and so defines a new paradigm for the large, multisubunit enzymes. Additional findings from these studies include a third nucleotide binding site that may define the length of backtracked RNA; DNA double helix unwinding in advance of the polymerase active center; and extension of the diffraction limit of RNA polymerase II crystals to 2.3 A.",
"The enzyme F1-ATPase has been shown to be a rotary motor in which the central gamma-subunit rotates inside the cylinder made of alpha3beta3 subunits. At low ATP concentrations, the motor rotates in discrete 120 degrees steps, consistent with sequential ATP hydrolysis on the three beta-subunits. The mechanism of stepping is unknown. Here we show by high-speed imaging that the 120 degrees step consists of roughly 90 degrees and 30 degrees substeps, each taking only a fraction of a millisecond. ATP binding drives the 90 degrees substep, and the 30 degrees substep is probably driven by release of a hydrolysis product. The two substeps are separated by two reactions of about 1 ms, which together occupy most of the ATP hydrolysis cycle. This scheme probably applies to rotation at full speed ( approximately 130 revolutions per second at saturating ATP) down to occasional stepping at nanomolar ATP concentrations, and supports the binding-change model for ATP synthesis by reverse rotation of F1-ATPase.",
"Genetic and cell-based studies have implicated the PAF1 complex (PAF1C) in transcription-associated events, but there has been no evidence showing a direct role in facilitating transcription of a natural chromatin template. Here, we demonstrate an intrinsic ability of human PAF1C (hPAF1C) to facilitate activator (p53)- and histone acetyltransferase (p300)-dependent transcription elongation from a recombinant chromatin template in a biochemically defined RNA polymerase II transcription system. This represents a PAF1C function distinct from its established role in histone ubiquitylation and methylation. Importantly, we further demonstrate a strong synergy between hPAF1C and elongation factor SII/TFIIS and an underlying mechanism involving direct hPAF1C-SII interactions and cooperative binding to RNA polymerase II. Apart from a distinct PAF1C function, the present observations provide a molecular mechanism for the cooperative function of distinct transcription elongation factors in chromatin transcription.",
"During transcription, RNA polymerase (RNAP) moves processively along a DNA template, creating a complementary RNA. Here we present the development of an ultra-stable optical trapping system with ångström-level resolution, which we used to monitor transcriptional elongation by single molecules of Escherichia coli RNAP. Records showed discrete steps averaging 3.7 +/- 0.6 A, a distance equivalent to the mean rise per base found in B-DNA. By combining our results with quantitative gel analysis, we conclude that RNAP advances along DNA by a single base pair per nucleotide addition to the nascent RNA. We also determined the force-velocity relationship for transcription at both saturating and sub-saturating nucleotide concentrations; fits to these data returned a characteristic distance parameter equivalent to one base pair. Global fits were inconsistent with a model for movement incorporating a power stroke tightly coupled to pyrophosphate release, but consistent with a brownian ratchet model incorporating a secondary NTP binding site.",
"Domain 10 of type III fibronectin (10FNIII) is known to play a pivotal role in the mechanical interactions between cell surface integrins and the extracellular matrix. Recent molecular dynamics simulations have predicted that 10FNIII, when exposed to a stretching force, unfolds along two pathways, each with a distinct, mechanically stable intermediate. Here, we use single-molecule force spectroscopy combined with protein engineering to test these predictions by probing the mechanical unfolding pathway of 10FNIII. Stretching single polyproteins containing the 10FNIII module resulted in sawtooth patterns where 10FNIII was seen unfolding in two consecutive steps. The native state unfolded at 100(+/-20) pN, elongating (10)FNIII by 12(+/-2) nm and reaching a clearly marked intermediate that unfolded at 50(+/-20) pN. Unfolding of the intermediate completed the elongation of the molecule by extending another 19(+/-2) nm. Site-directed mutagenesis of residues in the A and B beta-strands (E9P and L19P) resulted in sawtooth patterns with all-or-none unfolding events that elongated the molecule by 19(+/-2) nm. In contrast, mutating residues in the G beta-strand gave results that were dependent on amino acid position. The mutation I88P in the middle of the G beta-strand resulted in native like unfolding sawtooth patterns showing an intact intermediate state. The mutation Y92P, which is near the end of G beta-strand, produced sawtooth patterns with all-or-none unfolding events that lengthened the molecule by 17(+/-2) nm. These results are consistent with the view that 10FNIII can unfold in two different ways. Along one pathway, the detachment of the A and B beta-strands from the body of the folded module constitute the first unfolding event, followed by the unfolding of the remaining beta-sandwich structure. Along the second pathway, the detachment of the G beta-strands is involved in the first unfolding event. These results are in excellent agreement with the sequence of events predicted by molecular dynamics simulations of the 10FNIII module."
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Rx100: a novel lipid mediator that blocks activation of CFTR-mediated secretion in secretory diarrhea.
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A critical barrier in treating diarrheal disease is easy-to-use effective treatments. Rx100 is a first in class, novel small molecule that has shown efficacy after both subcutaneous and oral administration in a mouse cholera-toxin- and Citrobacter rodentium infection-induced diarrhea models. Our findings indicate that Rx100 a metabolically stable analog of the lipid mediator lysophosphatidic acid blocks activation of CFTR-mediated secretion responsible for fluid discharge in secretory diarrhea. Rx100 represents a new treatment modality which does not directly block CFTR but attenuates its activation by bacterial toxins. Our results provide proof-of-principle that Rx100 can be developed for use as an effective oral or injectable easy-to-use drug for secretory diarrhea which could significantly improve care by eliminating the need for severely ill patients to regularly consume large quantities of oral rehydration therapies and offering options for pediatric patients.
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[
"Annexin V and Sytox Green are widely used markers to evaluate apoptosis in various cell types using flow cytometry and fluorescent microscopy. Recently, a novel fluoroprobe MitoSOX Red was introduced for selective detection of superoxide in the mitochondria of live cells and was validated for confocal microscopy and flow cytometry. This protocol describes simultaneous measurements of mitochondrial superoxide generation with apoptotic markers (Annexin V and Sytox Green) by both flow cytometry and confocal microscopy in endothelial cell lines. The advantages of the described flow cytometry method over other cell-based techniques are the tremendous speed (1-2 h), exquisite precision and the possibility of simultaneous quantitative measurements of mitochondrial superoxide generation and apoptotic (and other) markers, with maximal preservation of cellular functions. This method combined with fluorescent microscopy may be very useful to reveal important spatial-temporal changes in mitochondrial superoxide production and execution of programmed cell death in virtually any cell type.",
"Hirschsprung disease-associated enterocolitis (HAEC) leads to significant mortality and morbidity, but its pathogenesis remains unknown. Changes in the colonic epithelium related to goblet cells and the luminal mucus layer have been postulated to play a key role. Here we show that the colonic epithelium of both aganglionic and ganglionic segments are altered in patients and in mice with Hirschsprung disease (HSCR). Structurally, goblet cells were altered with increased goblet cell number and reduced intracellular mucins in the distal colon of biopsies from patients with HSCR. Endothelin receptor B (Ednrb) mutant mice showed increased goblet cell number and size and increased cell proliferation compared to wild-type mice in aganglionic segments, and reduced goblet cell size and number in ganglionic segments. Functionally, compared to littermates, Ednrb-/- mice showed increased transepithelial resistance, reduced stool water content and similar chloride secretion in the distal colon. Transcript levels of goblet cell differentiation factors SPDEF and Math1 were increased in the distal colon of Ednrb-/- mice. Both distal colon from Ednrb mice and biopsies from HSCR patients showed reduced Muc4 expression as compared to controls, but similar expression of Muc2. Particle tracking studies showed that mucus from Ednrb-/- mice provided a more significant barrier to diffusion of 200 nm nanoparticles as compared to wild-type mice. These results suggest that aganglionosis is associated with increased goblet cell proliferation and differentiation and subsequent altered surface mucus properties, prior to the development of inflammation in the distal colon epithelium. Restoration of normal goblet cell function and mucus layer properties in the colonic epithelium may represent a therapeutic strategy for prevention of HAEC.",
"Oral rehydration solution (ORS) is lifesaving therapy for cholera and pediatric diarrhea. During a cholera epidemic in Guinea-Bissau, we evaluated the microbiologic quality of ORS prepared at a hospital and tested a simple intervention using special vessels for disinfecting tap water with bleach and for preparing, storing, and dispensing ORS. Few coliform bacteria and Escherichia coli were recovered from tap water; however, pre-intervention ORS contained numerous bacteria including E. coli and toxigenic Vibrio cholerae O1. In contrast, ORS samples from intervention vessels had few or no coliform bacteria, no E. coli, and no V. cholerae. Mean pre-intervention counts of coliform bacteria (3.4 x 10(7) colony-forming units [cfu]/100 ml) and E. coli (6.2 x 10(3) cfu) decreased significantly during the intervention period to 3.6 x 10(2) cfu and 0 cfu, respectively (P < 0.001). This simple system using bleach disinfectant and special storage vessels prevents bacterial contamination of ORS and reduces the risk of nosocomial transmission of cholera and other enteric pathogens.",
"We have previously demonstrated that the small molecule octadecenyl thiophosphate (OTP), a synthetic mimic of the growth factor-like mediator lysophosphatidic acid (LPA), showed radioprotective activity in a mouse model of total-body irradiation (TBI) when given orally or intraperitoneally 30 min before exposure to 9 Gy γ radiation. In the current study, we evaluated the effects of OTP, delivered subcutaneously, for radioprotection or radiomitigation from -24 h before to up to +72 h postirradiation using a mouse TBI model with therapeutic doses at around 1 mg/kg. OTP was injected at 10 mg/kg without observable toxic side effects in mice, providing a comfortable safety margin. Treatment of C57BL/6 mice with a single dose of OTP over the time period from -12 h before to +26 h after a lethal dose of TBI reduced mortality by 50%. When administered at +48 h to +72 h postirradiation (LD50/30 to LD100/30), OTP reduced mortality by ≥34%. OTP administered at +24 h postirradiation significantly elevated peripheral white blood cell and platelet counts, increased crypt survival in the jejunum, enhanced intestinal glucose absorption and reduced endotoxin seepage into the blood. In the 6.4-8.6 Gy TBI range using LD50/10 as the end point, OTP yielded a dose modification factor of 1.2. The current data indicate that OTP is a potent radioprotector and radiomitigator ameliorating the mortality and tissue injury of acute hematopoietic as well as acute gastrointestinal radiation syndrome.",
"TMEM16A was found recently to be a calcium-activated Cl(-) channel (CaCC). CaCCs perform important functions in cell physiology, including regulation of epithelial secretion, cardiac and neuronal excitability, and smooth muscle contraction. CaCC modulators are of potential utility for treatment of hypertension, diarrhea, and cystic fibrosis. Screening of drug and natural product collections identified tannic acid as an inhibitor of TMEM16A, with IC(50) ∼ 6 μM and ∼100% inhibition at higher concentrations. Tannic acid inhibited CaCCs in multiple cell types but did not affect CFTR Cl(-) channels. Structure-activity analysis indicated the requirement of gallic or digallic acid substituents on a macromolecular scaffold (gallotannins), as are present in green tea and red wine. Other polyphenolic components of teas and wines, including epicatechin, catechin, and malvidin-3-glucoside, poorly inhibited CaCCs. Remarkably, a 1000-fold dilution of red wine and 100-fold dilution of green tea inhibited CaCCs by >50%. Tannic acid, red wine, and green tea inhibited arterial smooth muscle contraction and intestinal Cl(-) secretion. Gallotannins are thus potent CaCC inhibitors whose biological activity provides a potential molecular basis for the cardioprotective and antisecretory benefits of red wine and green tea.",
"A videomicroscopic method was used to quantitatively analyze villous motility in the dog small intestine. The frequency and duration of villous contractions (retractions) were measured in the duodenum, midjejunum, and distal ileum under controlled conditions. A pronounced gradient of villous motility was evident along the bowel. The duodenum exhibited the highest frequency (7.3 +/- 0.1/min) and longest duration (2.6 +/- 0.1 s) of contraction; the jejunum exhibited an intermediate frequency and duration of contraction (4.0 +/- 0.1/min, 2.1 +/- 0.1 s), and the lowest values were measured in the ileum (2.0 +/- 0.1/min and 1.8 +/- 0.1 s). In contrast to the retraction movements, the frequency of pendular villous movements (whipping, swaying movements without shortening) was highest in the jejunum and lowest in the duodenum. The frequency and duration of villous contractions (retractions) remained relatively constant over a 2-h observation period. Reducing mucosal surface temperature from 38 to 30 degrees C caused the frequency of contraction to fall by 33% and the duration to increase by 106%. Varying the suffusate pH within the physiological range of 5.0-7.4 produced no significant effects on jejunal villous motility. Suffusion with glucose (140 and 280 mM) failed to alter villous motility. However, amino acid (15 and 30 mM) and fatty acid (10 mM) solutions significantly increased contraction frequency by 30-50% and 90%, respectively. The videomicroscopic method provides useful quantitative information, which should extend current knowledge regarding the regulation and physiological importance of villous motility.",
"The intestinal epithelium is subjected to various types of mechanical stress. In this study, we investigated the impact of cyclic stretch on tight junction and adherens junction integrity in Caco-2 cell monolayers. Stretch for 2 h resulted in a dramatic modulation of tight junction protein distribution from a linear organization into wavy structure. Continuation of cyclic stretch for 6 h led to redistribution of tight junction proteins from the intercellular junctions into the intracellular compartment. Disruption of tight junctions was associated with redistribution of adherens junction proteins, E-cadherin and β-catenin, and dissociation of the actin cytoskeleton at the actomyosin belt. Stretch activates JNK2, c-Src, and myosin light-chain kinase (MLCK). Inhibition of JNK, Src kinase or MLCK activity and knockdown of JNK2 or c-Src attenuated stretch-induced disruption of tight junctions, adherens junctions, and actin cytoskeleton. Paracellular permeability measured by a novel method demonstrated that cyclic stretch increases paracellular permeability by a JNK, Src kinase, and MLCK-dependent mechanism. Stretch increased tyrosine phosphorylation of occludin, ZO-1, E-cadherin, and β-catenin. Inhibition of JNK or Src kinase attenuated stretch-induced occludin phosphorylation. Immunofluorescence localization indicated that phospho-MLC colocalizes with the vesicle-like actin structure at the actomyosin belt in stretched cells. On the other hand, phospho-c-Src colocalizes with the actin at the apical region of cells. This study demonstrates that cyclic stretch disrupts tight junctions and adherens junctions by a JNK2, c-Src, and MLCK-dependent mechanism."
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Sitagliptin prevents perioperative stress hyperglycemia in patients without prior history of diabetes mellitus undergoing general surgery
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We investigated if a dipeptidyl peptidase-4 inhibitor, sitagliptin, can prevent perioperative stress hyperglycemia in patients without prior history of diabetes mellitus undergoing general surgery.
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[
"Stress hyperglycemia is common and likely to be associated with at least some of the same complications as hyperglycemia in true diabetes mellitus, such as poor wound healing and a higher infection rate. The predominant cause is the intense counterregulatory hormone and cytokine responses of critical illness, often compounded by excessive dextrose administration, usually as TPN. Although randomized data suggesting benefit of controlling hyperglycemia in hospitalized patients are paltry, prospective controlled trials are feasible and should be initiated. In the interim, the practice at the authors' institution is to use insulin to lower plasma glucose concentrations to a safe range of 150 mg/dL to 200 mg/dL in all patients.",
"We sought to study the optimal management of hyperglycemia in non-intensive care unit patients with type 2 diabetes, as few studies thus far have focused on the subject. We conducted a prospective, multicenter, randomized trial to compare the efficacy and safety of a basal-bolus insulin regimen with that of sliding-scale regular insulin (SSI) in patients with type 2 diabetes. A total of 130 insulin-naive patients were randomized to receive glargine and glulisine (n = 65) or a standard SSI protocol (n = 65). Glargine was given once daily and glulisine before meals at a starting dose of 0.4 units x kg(-1) x day(-1) for blood glucose 140-200 mg/dl or 0.5 units x kg(-1) x day(-1) for blood glucose 201-400 mg/dl. SSI was given four times per day for blood glucose >140 mg/dl. The mean admission blood glucose was 229 +/- 6 mg/dl and A1C 8.8 +/- 2%. A blood glucose target of <140 mg/dl was achieved in 66% of patients in the glargine and glulisine group and in 38% of those in the SSI group. The mean daily blood glucose between groups ranged from 23 to 58 mg/dl, with an overall blood glucose difference of 27 mg/dl (P < 0.01). Despite increasing insulin doses, 14% of patients treated with SSI remained with blood glucose >240 mg/dl. There were no differences in the rate of hypoglycemia or length of hospital stay. Treatment with insulin glargine and glulisine resulted in significant improvement in glycemic control compared with that achieved with the use of SSI alone. Our study indicates that a basal-bolus insulin regimen is preferred over SSI in the management of non-critically ill, hospitalized patients with type 2 diabetes.",
"This study investigated the safety and efficacy of sitagliptin (Januvia) for the inpatient management of type 2 diabetes (T2D) in general medicine and surgery patients. In this pilot, multicenter, open-label, randomized study, patients (n = 90) with a known history of T2D treated with diet, oral antidiabetic agents, or low total daily dose of insulin (≤0.4 units/kg/day) were randomized to receive sitagliptin alone or in combination with glargine insulin (glargine) or to a basal bolus insulin regimen (glargine and lispro) plus supplemental (correction) doses of lispro. Major study outcomes included differences in daily blood glucose (BG), frequency of treatment failures (defined as three or more consecutive BG >240 mg/dL or a mean daily BG >240 mg/dL), and hypoglycemia between groups. Glycemic control improved similarly in all treatment groups. There were no differences in the mean daily BG after the 1st day of treatment (P = 0.23), number of readings within a BG target of 70 and 140 mg/dL (P = 0.53), number of BG readings >200 mg/dL (P = 0.23), and number of treatment failures (P > 0.99). The total daily insulin dose and number of insulin injections were significantly less in the sitagliptin groups compared with the basal bolus group (both P < 0.001). There were no differences in length of hospital stay (P = 0.78) or in the number of hypoglycemic events between groups (P = 0.86). Results of this pilot indicate that treatment with sitagliptin alone or in combination with basal insulin is safe and effective for the management of hyperglycemia in general medicine and surgery patients with T2D.",
"The role of incretin-based drugs in the treatment of patients with type 2 diabetes admitted to hospital has not been extensively assessed. In this study, we compared the safety and efficacy of a dipeptidyl peptidase-4 inhibitor (sitagliptin) plus basal insulin with a basal-bolus insulin regimen for the management of patients with type 2 diabetes in general medicine and surgery in hospitals. We did a multicentre, prospective, open-label, non-inferiority randomised clinical trial (Sita-Hospital) in five hospitals in the USA, enrolling patients aged 18-80 years with type 2 diabetes and a random blood glucose concentration of 7·8-22·2 mmol/L who were being treated with diet or oral antidiabetic drugs or had a total daily insulin dose of 0·6 units per kg or less, admitted to general medicine and surgery services. We randomly assigned patients (1:1) to receive either sitagliptin plus basal glargine once daily (the sitagliptin-basal group) or a basal-bolus regimen with glargine once daily and rapid-acting insulin lispro or aspart before meals (the basal-bolus group) during the hospital stay. All other antidiabetic drugs were discontinued on admission. The randomisation was achieved by computer-generated tables with block stratification according to randomisation blood glucose concentrations (ie, higher or lower than 11·1 mmol/L). The primary endpoint of the trial was non-inferiority in mean differences between groups in their daily blood glucose concentrations during the first 10 days of therapy (point-of-care measurements; non-inferiority was deemed a difference <1 mmol/L). The safety endpoints included hypoglycaemia and uncontrolled hyperglycaemia leading to treatment failure. All participants who received at least one dose of study drug were included in the analysis. This study is registered with ClinicalTrials.gov, number NCT01845831. Between Aug 23, 2013, and July 27, 2015, we recruited 279 patients, and randomly assigned 277 to treatment; 138 to sitagliptin-basal and 139 to basal-bolus. The length of stay in hospital was similar for both groups (median 4 days [IQR 3-8] vs 4 [3-8] days, p=0·54). The mean daily blood glucose concentration in the sitagliptin-basal group (9·5 mmol/L [SD 2·7]) was not inferior to that in the basal-bolus group 9·4 mmol/L [2·7]) with a mean blood glucose difference of 0·1 mmol/L (95% CI -0·6 to 0·7). No deaths occurred in this trial. Treatment failure occurred in 22 patients (16%) in the sitagliptin-basal group versus 26 (19%) in the basal-bolus group (p=0·54). Hypoglycaemia occurred in 13 patients (9%) in the sitagliptin-basal group and in 17 (12%) in the basal-bolus group (p=0·45). No differences in hospital complications were noted between groups. Seven patients (5%) developed acute kidney injury in the sitagliptin-basal group and six (4%) in the basal-bolus group. One patient (0·7%) developed acute pancreatitis (in the basal-bolus group). The trial met the non-inferiority threshold for the primary endpoint, because there was no significant difference between groups in mean daily blood glucose concentrations. Treatment with sitagliptin plus basal insulin is as effective and safe as, and a convenient alternative to, the labour-intensive basal-bolus insulin regimen for the management of hyperglycaemia in patients with type 2 diabetes admitted to general medicine and surgery services in hospital in the non-intensive-care setting. Merck.",
"Diabetes mellitus is an established independent risk factor for significant morbidity and mortality after coronary artery bypass grafting. The impact of diabetes on short- and longterm follow-up after coronary artery bypass grafting was studied by comparing the outcomes between 9,920 patients without diabetes mellitus and 2,278 patients with diabetes from 1978 to 1993. Compared with nondiabetic patients, the group with diabetes was older (62+/-10 years versus 60+/-10 years), comprised more women (31% versus 19%), had a greater incidence of hypertension (61% versus 44%) and previous myocardial infarction (51% versus 48%), had class III-IV angina more commonly (69% versus 63%), showed a higher incidence of congestive heart failure (11% versus 5%) or triple-vessel or left main disease (60% versus 50%), and had lower ejection fractions (0.54 versus 0.57) (all, p< or =0.05). Diabetic patients had a higher incidence of postoperative death (3.9% versus 1.6%) and stroke (2.9% versus 1.4%) (both, p< or =0.05), but not Q wave myocardial infarction (1.8% versus 2.9%). Diabetics had lower survival (5 years, 78% versus 88%; 10 years, 50% versus 71%; both, p< or =0.05) and lower freedom from percutaneous transluminal coronary angioplasty (5 years, 95% versus 96%; 10 years, 83% versus 86%; latter, p< or =0.05), but diabetics did not have lower freedom from either myocardial infarction (5-years, 92% versus 92%; 10-years, 80% versus 84%) or additional coronary artery bypass grafting (5-years, 98% versus 99%; 10-years, 90% versus 91%). Multivariate correlates of long-term mortality were diabetes, older age, reduced ejection fraction, hypertension, congestive heart failure, number of vessels diseased, and urgent or emergent operation. Diabetics have a worse hospital and longterm outcome after coronary artery bypass grafting. The increased risk in such patients can only partially be explained by other demographic characteristics.",
"The aim was to formulate practice guidelines on the management of hyperglycemia in hospitalized patients in the non-critical care setting. The Task Force was composed of a chair, selected by the Clinical Guidelines Subcommittee of The Endocrine Society, six additional experts, and a methodologist. This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. One group meeting, several conference calls, and e-mail communications enabled consensus. Endocrine Society members, American Diabetes Association, American Heart Association, American Association of Diabetes Educators, European Society of Endocrinology, and the Society of Hospital Medicine reviewed and commented on preliminary drafts of this guideline. Hyperglycemia is a common, serious, and costly health care problem in hospitalized patients. Observational and randomized controlled studies indicate that improvement in glycemic control results in lower rates of hospital complications in general medicine and surgery patients. Implementing a standardized sc insulin order set promoting the use of scheduled basal and nutritional insulin therapy is a key intervention in the inpatient management of diabetes. We provide recommendations for practical, achievable, and safe glycemic targets and describe protocols, procedures, and system improvements required to facilitate the achievement of glycemic goals in patients with hyperglycemia and diabetes admitted in non-critical care settings.",
"In healthy humans, the incretin glucagon-like peptide 1 (GLP-1) is secreted after eating and lowers glucose concentrations by augmenting insulin secretion and suppressing glucagon release. Additional effects of GLP-1 include retardation of gastric emptying, suppression of appetite and, potentially, inhibition of β-cell apoptosis. Native GLP-1 is degraded within ~2-3 min in the circulation; various GLP-1 receptor agonists have, therefore, been developed to provide prolonged in vivo actions. These GLP-1 receptor agonists can be categorized as either short-acting compounds, which provide short-lived receptor activation (such as exenatide and lixisenatide) or as long-acting compounds (for example albiglutide, dulaglutide, exenatide long-acting release, and liraglutide), which activate the GLP-1 receptor continuously at their recommended dose. The pharmacokinetic differences between these drugs lead to important differences in their pharmacodynamic profiles. The short-acting GLP-1 receptor agonists primarily lower postprandial blood glucose levels through inhibition of gastric emptying, whereas the long-acting compounds have a stronger effect on fasting glucose levels, which is mediated predominantly through their insulinotropic and glucagonostatic actions. The adverse effect profiles of these compounds also differ. The individual properties of the various GLP-1 receptor agonists might enable incretin-based treatment of type 2 diabetes mellitus to be tailored to the needs of each patient."
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Fam65b Regulates Intranodal T Cell Migration in Resting T Lymphocytes
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We previously identified Fam65b as an atypical inhibitor of the small G protein RhoA. Using a conditional model of a Fam65b-deficient mouse, we first show that Fam65b restricts spontaneous RhoA activation in resting T lymphocytes and regulates intranodal T cell migration
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[
"Cell quiescence is controlled by regulated genome-encoded programs that actively express genes which are often down-regulated or inactivated in transformed cells. Among them is FoxO1, a transcription factor that imposes quiescence in several cell types, including T lymphocytes. In these cells, the FAM65B encoding gene is a major target of FOXO1. Here, we show that forced expression of FAM65B in transformed cells blocks their mitosis because of a defect of the mitotic spindle, leading to G2 cell cycle arrest and apoptosis. Upon cell proliferation arrest, FAM65B is engaged in a complex containing two proteins well known to be involved in cell proliferation i.e. the HDAC6 deacetylase and the 14.3.3 scaffolding protein. In primary T cells, FAM65B is down-regulated upon T cell receptor engagement, and maintaining its expression blocks their proliferation, establishing that the decrease of FAM65B expression is required for proliferation. Conversely, inhibiting FAM65B expression in naive T lymphocytes decreases their activation threshold. These results identify FAM65B as a potential new target for controlling proliferation of both transformed and normal cells.",
"ROCKs, or Rho kinases, are serine/threonine kinases that are involved in many aspects of cell motility, from smooth-muscle contraction to cell migration and neurite outgrowth. Recent experiments have defined new functions of ROCKs in cells, including centrosome positioning and cell-size regulation, which might contribute to various physiological and pathological states.",
"A hallmark of neutrophil polarization is the back localization of active RHOA and phosphorylated myosin light chain (pMLC, also known as MYL2). However, the mechanism for the polarization is not entirely clear. Here, we show that FAM65B, a newly identified RHOA inhibitor, is important for the polarization. When FAM65B is phosphorylated, it binds to 14-3-3 family proteins and becomes more stable. In neutrophils, chemoattractants stimulate FAM65B phosphorylation largely depending on the signals from the front of the cells that include those mediated by phospholipase Cβ (PLCβ) and phosphoinositide 3-kinase γ (PI3Kγ), leading to FAM65B accumulation at the leading edge. Concordantly, FAM65B deficiency in neutrophils resulted in an increase in RHOA activity and localization of pMLC to the front of cells, as well as defects in chemotaxis directionality and adhesion to endothelial cells under flow. These data together elucidate a mechanism for RHOA and pMLC polarization in stimulated neutrophils through direct inhibition of RHOA by FAM65B at the leading edge.",
"The small GTPase RhoA has been implicated in various cellular activities, including the formation of stress fibers, cell motility, and cytokinesis. In addition to the canonical GTPase cycle, recent findings have suggested that phosphorylation further contributes to the tight regulation of Rho GTPases. Indeed, RhoA is phosphorylated on serine 188 (188S) by a number of protein kinases. We have recently reported that Rac1 is phosphorylated on threonine 108 (108T) by extracellular signal-regulated kinases (ERK) in response to epidermal growth factor (EGF) stimulation. Here, we provide evidence that RhoA is phosphorylated by ERK on 88S and 100T in response to EGF stimulation. We show that ERK interacts with RhoA and that this interaction is dependent on the ERK docking site (D-site) at the C-terminus of RhoA. EGF stimulation enhanced the activation of the endogenous RhoA. The phosphomimetic mutant, GFP-RhoA S88E/T100E, when transiently expressed in COS-7 cells, displayed higher GTP-binding than wild type RhoA. Moreover, the expression of GFP-RhoA S88E/T100E increased actin stress fiber formation in COS-7 cells, which is consistent with its higher activity. In contrast to Rac1, phosphorylation of RhoA by ERK does not target RhoA to the nucleus. Finally, we show that regardless of the phosphorylation status of RhoA and Rac1, substitution of the RhoA PBR with the Rac1 PBR targets RhoA to the nucleus and substitution of Rac1 PBR with RhoA PBR significantly reduces the nuclear localization of Rac1. In conclusion, ERK phosphorylates RhoA on 88S and 100T in response to EGF, which upregulates RhoA activity.",
"The cilium is a complex organelle, the assembly of which requires the coordination of motor-driven intraflagellar transport (IFT), membrane trafficking and selective import of cilium-specific proteins through a barrier at the ciliary transition zone. Recent findings provide insights into how cilia assemble and disassemble in synchrony with the cell cycle and how the balance of ciliary assembly and disassembly determines the steady-state ciliary length, with the inherent length-dependence of IFT rendering the ciliary assembly rate a decreasing function of length. As cilia are important in sensing and processing developmental signals and directing the flow of fluids such as mucus, defects in ciliogenesis and length control are likely to underlie a range of cilium-related human diseases.",
"Accumulating evidence has implicated Rho GTPases, including Rac1, in many aspects of cancer development. Recent findings suggest that phosphorylation might further contribute to the tight regulation of Rho GTPases. Interestingly, sequence analysis of Rac1 shows that Rac1 T108 within the (106)PNTP(109) motif is likely an extracellular signal-regulated kinase (ERK) phosphorylation site and that Rac1 also has an ERK docking site, (183)KKRKRKCLLL(192) (D site), at the C terminus. Indeed, we show here that both transfected and endogenous Rac1 interacts with ERK and that this interaction is mediated by its D site. Green fluorescent protein (GFP)-Rac1 is threonine (T) phosphorylated in response to epidermal growth factor (EGF), and EGF-induced Rac1 threonine phosphorylation is dependent on the activation of ERK. Moreover, mutant Rac1 with the mutation of T108 to alanine (A) is not threonine phosphorylated in response to EGF. In vitro ERK kinase assay further shows that pure active ERK phosphorylates purified Rac1 but not mutant Rac1 T108A. We also show that Rac1 T108 phosphorylation decreases Rac1 activity, partially due to inhibiting its interaction with phospholipase C-γ1 (PLC-γ1). T108 phosphorylation targets Rac1 to the nucleus, which isolates Rac1 from other guanine nucleotide exchange factors (GEFs) and hinders Rac1's role in cell migration. We conclude that Rac1 T108 is phosphorylated by ERK in response to EGF, which plays an important role in regulating Rac1.",
"Actin assembly at the cell front drives membrane protrusion and initiates the cell migration cycle. Microtubules (MTs) extend within forward protrusions to sustain cell polarity and promote adhesion site turnover. Memo is an effector of the ErbB2 receptor tyrosine kinase involved in breast carcinoma cell migration. However, its mechanism of action remained unknown. We report in this study that Memo controls ErbB2-regulated MT dynamics by altering the transition frequency between MT growth and shortening phases. Moreover, although Memo-depleted cells can assemble the Rac1-dependent actin meshwork and form lamellipodia, they show defective localization of lamellipodial markers such as alpha-actinin-1 and a reduced number of short-lived adhesion sites underlying the advancing edge of migrating cells. Finally, we demonstrate that Memo is required for the localization of the RhoA guanosine triphosphatase and its effector mDia1 to the plasma membrane and that Memo-RhoA-mDia1 signaling coordinates the organization of the lamellipodial actin network, adhesion site formation, and MT outgrowth within the cell leading edge to sustain cell motility.",
"The transit of T lymphocytes through the cell cycle in response to extracellular signals is controlled in large part by the ordered expression and degradation of cyclins and cyclin-dependent kinases and their negative regulators, the cyclin-dependent kinase inhibitors. This review outlines findings that have provided insights into how T lymphocytes integrate signals from their antigen, costimulatory, and cytokine receptors to drive cell cycle progression and discusses how the coordinated activities of these families of proteins influence multiple aspects of T-cell function, from thymic development and peripheral homeostasis to antigen-driven responses and the induction of T-cell memory and tolerance.",
"Directional cell migration involves reorientation of the secretory machinery. However, the molecular mechanisms that control this reorientation are not well characterised. Here, we identify a new Rho effector protein, named FAM65A, which binds to active RHOA, RHOB and RHOC. FAM65A links RHO proteins to Golgi-localising cerebral cavernous malformation-3 protein (CCM3; also known as PDCD10) and its interacting proteins mammalian STE20-like protein kinases 3 and 4 (MST3 and MST4; also known as STK24 and STK26, respectively). Binding of active RHO proteins to FAM65A does not affect the kinase activity of MSTs but results in their relocation from the Golgi in a CCM3-dependent manner. This relocation is crucial for reorientation of the Golgi towards the leading edge and subsequent directional cell migration. Our results reveal a previously unidentified pathway downstream of RHO that regulates the polarity of migrating cells through Golgi reorientation in a FAM65A-, CCM3- and MST3- and MST4-dependent manner.",
"The 14-3-3 proteins were the first phosphoserine/phosphothreonine-binding proteins to be discovered, a finding that provided the foundation for their prominent role in cell signaling. 14-3-3 family members interact with a wide spectrum of proteins including transcription factors, biosynthetic enzymes, cytoskeletal proteins, signaling molecules, apoptosis factors, and tumor suppressors. The interaction with 14-3-3 can have a profound effect on a target protein, altering its localization, stability, conformation, phosphorylation state, activity, and/or molecular interactions. Thus, by modulating the function of a diverse array of binding partners, 14-3-3 proteins have become key regulatory components in many vital cellular processes - processes that are crucial for normal growth and development and that often become dysregulated in human cancer. This review will examine the recent advances that further elucidate the role of 14-3-3 proteins in normal growth and cancer signaling with a particular emphasis on the signaling pathways that impact cell proliferation, cell migration, and epithelial-to-mesenchymal transition."
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Current position of the Croatian Cooperative Group for Hematologic Disease on diagnosis and treatment of chronic lymphocytic leukemia
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Recent developments in the diagnosis and treatment of chronic lymphocytic leukemia (B-CLL) have led to change of approach in clinical practice. New treatments have been approved based on the results of randomized multicenter trials for first line and for salvage therapy, and the results of numerous ongoing clinical trials are permanently providing new answers and further refining of therapeutic strategies. This is paralleled by substantial increase in understanding the disease genetics due to major advances in the next generation sequencing (NGS) technology. We define current position of the Croatian Cooperative Group for Hematologic Disease on diagnosis and treatment of CLL in the transition from chemo-immunotherapy paradigm into a new one that is based on new diagnostic stratification and unprecedented therapeutic results of B-cell receptor inhibitors (BRI) and Bcl-2 antagonists. This is a rapidly evolving field as a great number of ongoing clinical trials con-stantly accumulate and provide new knowledge. We believe that novel therapy research including genomic diagnosis is likely to offer new options that will eventually lead to time limited therapies without chemotherapy and more effective clinical care for B-CLL based on individualized precision medicine.
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[
"Chronic lymphocytic leukemia is frequently associated with immune disturbances. The relationship between chronic lymphocytic leukemia and autoimmune cytopenias, particularly autoimmune hemolytic anemia and immune thrombocytopenia, is well established. The responsible mechanisms, particularly the role of leukemic cells in orchestrating the production of polyclonal autoantibodies, are increasingly well understood. Recent studies show that autoimmune cytopenia is not necessarily associated with poor prognosis. On the contrary, patients with anemia or thrombocytopenia due to immune mechanisms have a better outcome than those in whom these features are due to bone marrow infiltration by the disease. Moreover, fears about the risk of autoimmune hemolysis following single agent fludarabine may no longer be appropriate in the age of chemo-immunotherapy regimens. However, treatment of patients with active hemolysis may pose important problems needing an individualized and clinically sound approach. The concept that autoimmune cytopenia may precede the leukemia should be revisited in the light of recent data showing that autoimmune cytopenia may be observed in monoclonal B-cell lymphocytosis, a condition that can only be detected by using sensitive flow cytometry techniques. On the other hand, there is no evidence of an increased risk of non-hemic autoimmune disorders in chronic lymphocytic leukemia. Likewise, there is no epidemiological proof of an increased risk of chronic lymphocytic leukemia in patients with non-hemic autoimmunity. Finally, since immune disorders are an important part of chronic lymphocytic leukemia, studies aimed at revealing the mechanisms linking the neoplastic and the immune components of the disease should help our understanding of this form of leukemia.",
"To examine the impact of tumors on the immune system, we compared global gene expression profiles of peripheral blood T cells from previously untreated patients with B cell chronic lymphocytic leukemia (CLL) with those from age-matched healthy donors. Although the cells analyzed were not part of the malignant clone, analysis revealed differentially expressed genes, mainly involved in cell differentiation in CD4 cells and defects in cytoskeleton formation, vesicle trafficking, and cytotoxicity in CD8 cells of the CLL patients. In coculture experiments using CLL cells and T cells from healthy allogeneic donors, similar defects developed in both CD4 and CD8 cells. These changes were induced only with direct contact and were not cytokine mediated. Identification of the specific pathways perturbed in the T cells of cancer-bearing patients will allow us to assess steps to repair these defects, which will likely be required to enhance antitumor immunity.",
"Our interest in chronic lymphocytic leukemia (CLL) derives primarily from the exploitation of human diseases as strategic models for defining the in vivo biological roles of CD38. Using this model, we showed that CD38 triggers robust proliferation/survival signals modulated through the interactions with the CD31 ligand expressed by nurse-like cells and by the stromal/endothelial components. By analyzing a cohort of 56 patients with clinically and molecularly characterized CLL, we show that (1) patients with CD38(+)/ZAP-70(+) are characterized by enhanced migration toward Stromal derived factor-1alpha (SDF-1alpha)/CXCL12; (2) CD38 ligation leads to tyrosine phosphorylation of ZAP-70, showing that these markers are functionally linked; (3) ZAP-70 represents a limiting factor for the CD38 pathway in the CLL context, as shown by studying CD38-mediated signal transduction in 26 molecularly characterized patients; and (4) the CLL subgroup of patients defined on the basis of migratory potential is marked by a specific genetic signature, with a significant number of differentially expressed genes being involved in cell-cell interactions and movement. Altogether, the results of this work provide biological evidence for why the combined analysis of CD38 and ZAP-70 expression as determined in several clinical trials results in more dependable identification of patients with CLL who have aggressive disease.",
"Very low levels of circulating monoclonal B-cell subpopulations can now be detected in apparently healthy individuals using flow cytometry. We propose the term 'monoclonal B-cell lymphocytosis' (MBL) to describe this finding. The aim of this document is to provide a working definition of MBL for future clinical, epidemiological and laboratory studies. We propose that the detection of a monoclonal B-cell population by light chain restriction is sufficient to define this condition in individuals not meeting the diagnostic criteria for other B-lymphoproliferative disorders. The majority of individuals with MBL will have cells that are indistinguishable from chronic lymphocytic leukaemia (CLL). However, this blood cell clonal expansion of CD5+ or CD5- B-lymphocytes is age-dependent and immunophenotypic heterogeneity is common. Longitudinal studies are required to determine whether MBL is a precursor state to CLL or other B-lymphoproliferative disease in a situation analogous to a monoclonal gammopathy of undetermined significance and myeloma. Future studies of MBL should be directed towards determining its relationship to clinical disease, particularly in individuals from families with a genetic predisposition to developing CLL.",
"One hundred patients with lymphoproliferative disease were reviewed. Seven of these patients were found to develop an autoimmune complication following the use of radiation or radiomimetic drug. The literature suggesting that radiation can enhance as well as suppress the autoimmune response is summarized, and the possibility that therapy can trigger autoimmunity in these patients is emphasized.",
"The diagnostic criteria for CLL rely on morphology and immunophenotype. Current approaches have limitations affecting reproducibility and there is no consensus on the role of new markers. The aim of this project was to identify reproducible criteria and consensus on markers recommended for the diagnosis of CLL. ERIC/ESCCA members classified 14 of 35 potential markers as \"required\" or \"recommended\" for CLL diagnosis, consensus being defined as >75% and >50% agreement, respectively. An approach to validate \"required\" markers using normal peripheral blood was developed. Responses were received from 150 participants with a diagnostic workload >20 CLL cases per week in 23/150 (15%), 5-20 in 82/150 (55%), and <5 cases per week in 45/150 (30%). The consensus for \"required\" diagnostic markers included: CD19, CD5, CD20, CD23, Kappa, and Lambda. \"Recommended\" markers potentially useful for differential diagnosis were: CD43, CD79b, CD81, CD200, CD10, and ROR1. Reproducible criteria for component reagents were assessed retrospectively in 14,643 cases from 13 different centers and showed >97% concordance with current approaches. A pilot study to validate staining quality was completed in 11 centers. Markers considered as \"required\" for the diagnosis of CLL by the participants in this study (CD19, CD5, CD20, CD23, Kappa, and Lambda) are consistent with current diagnostic criteria and practice. Importantly, a reproducible approach to validate and apply these markers in individual laboratories has been identified. Finally, a consensus \"recommended\" panel of markers to refine diagnosis in borderline cases (CD43, CD79b, CD81, CD200, CD10, and ROR1) has been defined and will be prospectively evaluated. © 2017 International Clinical Cytometry Society.",
"279 B-CLL patients entered randomized IGCI clinical trial to compare the remission rate and survival of high dose continuous chlorambucil (regimen A) vs intermittent chlorambucil plus prednisone (regimen B), and to assess the effect of early treatment on survival. Regimen A was significantly better for remission induction (p less than 0.001), and prolonged survival (p less than 0.01) in comparison to regimen B. More aggressive chemotherapy is associated with better response but requires close monitoring of both antineoplastic effect and haematological toxicity. Total tumor mass score (TTM) proved to be suitable for definition of both early, stable disease and the response to therapy because of its quantitative continuous character and its independence of bone marrow failure. This system is helpful for the detection of treatment toxicity and consequently enables safe monitoring of therapy. Although statistically significant difference has not yet been reached between the patients treated early and non treated patients the latter group seems to fare better.",
"Chronic lymphocytic leukemia (CLL) is frequently associated with autoimmune diseases directed against constituents of the blood, including hemolytic anemia (AIHA). We hypothesized that CLL cells predispose to hematologic autoimmunity by acting as aberrant antigen-presenting cells (APCs). Initially, it was confirmed that all studied patients with AIHA secondary to CLL harbored activated helper T (T(H)) cells specific for epitopes on the dominant red blood cell (RBC) autoantigens in primary AIHA, the Rh proteins. Rh-specific T(H) cells were also detected in a number of patients with CLL who, although they did not have AIHA, had low levels of anti-RBC antibody in their sera. Fractionation of putative APC populations from the peripheral blood of patients by negative selection showed that CD5+ CLL cells are the most effective cell type in processing and presenting purified Rh protein to autoreactive T(H) cells. This ability was confirmed using positively selected CD5+ CLL cells. Thus, our study provides the first evidence for malignant cells driving an autoimmune response by acting as aberrant APCs.",
"Previous studies of patients with chronic lymphocytic leukaemia reported high response rates to fludarabine combined with cyclophosphamide. We aimed to establish whether this treatment combination provided greater survival benefit than did chlorambucil or fludarabine. 777 patients with chronic lymphocytic leukaemia requiring treatment were randomly assigned to fludarabine (n=194) or fludarabine plus cyclophosphamide (196) for six courses, or chlorambucil (387) for 12 courses. The primary endpoint was overall survival, with secondary endpoints of response rates, progression-free survival, toxic effects, and quality of life. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number NCT 58585610. There was no significant difference in overall survival between patients given fludarabine plus cyclophosphamide, fludarabine, or chlorambucil. Complete and overall response rates were better with fludarabine plus cyclophosphamide than with fludarabine (complete response rate 38%vs 15%, respectively; overall response rate 94%vs 80%, respectively; p<0.0001 for both comparisons), which were in turn better than with chlorambucil (complete response rate 7%, overall response rate 72%; p=0.006 and 0.04, respectively). Progression-free survival at 5 years was significantly better with fludarabine plus cyclophosphamide (36%) than with fludarabine (10%) or chlorambucil (10%; p<0.00005). Fludarabine plus cyclophosphamide was the best combination for all ages, including patients older than 70 years, and in prognostic groups defined by immunoglobulin heavy chain gene (V(H)) mutation status and cytogenetics, which were tested in 533 and 579 cases, respectively. Patients had more neutropenia and days in hospital with fludarabine plus cyclophosphamide, or fludarabine, than with chlorambucil. There was less haemolytic anaemia with fludarabine plus cyclophosphamide (5%) than with fludarabine (11%) or chlorambucil (12%). Quality of life was better for responders, but preliminary analyses showed no significant difference between treatments. A meta-analysis of these data and those of two published phase III trials showed a consistent benefit for the fludarabine plus cyclophosphamide regimen in terms of progression-free survival. Fludarabine plus cyclophosphamide should now become the standard treatment for chronic lymphocytic leukaemia and the basis for new protocols that incorporate monoclonal antibodies.",
"HLA-G appears to be involved in regulatory functions counteracting the cellular immune response of T and NK cells by several pathways. We here summarize the HLA-G expression patterns in leukaemia with emphasis on the clinical relevance of this expression for disease progression. Especially in patients with B-chronic lymphocytic leukaemia (B-CLL) the HLA-G expression on B-CLL cells was strongly associated with a reduced treatment-free survival. The corresponding immunological parameters point to a broad immunosuppression in these patients. Thus, HLA-G seems to contribute to the impaired immune response in B-CLL supporting disease progression."
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Single-particle cryo-electron microscopy of protein particles in thin liquid films
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Most protein particles prepared in vitreous ice for single-particle cryo-electron microscopy (cryo-EM) are adsorbed to air-water or substrate-water interfaces, which can cause the particles to adopt preferred orientations. By using a rapid plunge-freezing robot and nanowire grids, we were able to reduce some of the deleterious effects of the air-water interface by decreasing the dwell time of particles in thin liquid films. We demonstrated this by using single-particle cryo-EM and cryo-electron tomography (cryo-ET) to examine hemagglutinin, insulin receptor complex, and apoferritin.
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"Almost every aspect of cryo electron microscopy (cryoEM) has been automated over the last few decades. One of the challenges that remains to be addressed is the robust and reliable preparation of vitrified specimens of suitable ice thickness. We present results from a new device for preparing vitrified samples. The successful use of the device is coupled to a new \"self-blotting\" grid that we have developed to provide a method for spreading a sample to a thin film without the use of externally applied filter paper. This new approach has the advantage of using small amounts of protein material, resulting in large areas of ice of a well defined thickness containing evenly distributed single particles. We believe that these methods will in the future result in a system for vitrifying grids that is completely automated.",
"Two-dimensional analysis of projections of single-particles acquired by an electron microscope is a useful tool to help identifying the different kinds of projections present in a dataset and their different projection directions. Such analysis is also useful to distinguish between different kinds of particles or different particle conformations. In this paper we introduce a new algorithm for performing two-dimensional multireference alignment and classification that is based on a Hierarchical clustering approach using correntropy (instead of the more traditional correlation) and a modified criterion for the definition of the clusters specially suited for cases in which the Signal-to-Noise Ratio of the differences between classes is low. We show that our algorithm offers an improved sensitivity over current methods in use for distinguishing between different projection orientations and different particle conformations. This algorithm is publicly available through the software package Xmipp.",
"Thin vitrified layers of unfixed, unstained and unsupported virus suspensions can be prepared for observation by cryo-electron microscopy in easily controlled conditions. The viral particles appear free from the kind of damage caused by dehydration, freezing or adsorption to a support that is encountered in preparing biological samples for conventional electron microscopy. Cryo-electron microscopy of vitrified specimens offers possibilities for high resolution observations that compare favourably with any other electron microscopical method."
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Targeting miR-199b-5p/VEGF axis to blunt the development of drug resistance to BRAF-mutated metastatic melanoma
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Drug resistance imposes severe limitations to the efficacy of targeted therapy in BRAF-mutated metastatic melanoma. Although this issue has been mitigated by the development of combination therapies with BRAF plus MEK inhibitors, drug resistance inevitably occurs with time and results in clinical recurrences and untreatable disease. Hence, there is strong need of developing new combination therapies and non-invasive diagnostics for the early identification of drug-resistant patients. We report here that the development of drug resistance to BRAFi is dominated by a dynamic deregulation of a large population of miRNAs, leading to the alteration of cell intrinsic proliferation and survival pathways, as well as of proinflammatory and proangiogenic cues, where a prominent role is played by the miR-199b-5p/VEGF axis. Significant alterations of miRNA expression levels are detectable in tumor biopsies and plasma from patients after disease recurrence. Targeting these alterations blunts the development of drug resistance.
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[
"Therapy of melanoma patients harboring activating mutations in the BRAF (V-raf murine sarcoma viral oncogene homolog B1) oncogene with a combination of BRAF and MEK inhibitors is plagued by the development of drug resistance. Mutational events, as well as adaptive mechanisms, contribute to the development of drug resistance. In this context we uncover here the role of a miRNA, miR-579-3p. We first show that low expression of miR-579-3p is a negative prognostic factor correlating with poor survival. Expression levels of miR-579-3p decrease from nevi to stage III/IV melanoma samples and even further in cell lines resistant to BRAF/MEK inhibitors. Mechanistically, we demonstrate that miR-579-3p acts as an oncosuppressor by targeting the 3'UTR of two oncoproteins: BRAF and an E3 ubiquitin protein ligase, MDM2. Moreover miR-579-3p ectopic expression impairs the establishment of drug resistance in human melanoma cells. Finally, miR-579-3p is strongly down-regulated in matched tumor samples from patients before and after the development of resistance to targeted therapies.",
"Combined BRAF- and MEK-targeted therapy improves upon BRAF inhibitor (BRAFi) therapy but is still beset by acquired resistance. We show that melanomas acquire resistance to combined BRAF and MEK inhibition by augmenting or combining mechanisms of single-agent BRAFi resistance. These double-drug resistance-associated genetic configurations significantly altered molecular interactions underlying MAPK pathway reactivation. (V600E)BRAF, expressed at supraphysiological levels because of (V600E)BRAF ultra-amplification, dimerized with and activated CRAF. In addition, MEK mutants enhanced interaction with overexpressed (V600E)BRAF via a regulatory interface at R662 of (V600E)BRAF. Importantly, melanoma cell lines selected for resistance to BRAFi+MEKi, but not those to BRAFi alone, displayed robust drug addiction, providing a potentially exploitable therapeutic opportunity.",
"Recent studies have shown that immunotherapies and molecular targeted therapies are effective for advanced melanoma. Non-antigen-specific immunotherapies such as immunocheckpoint blockades have been shown to be effective in the treatment of advanced melanoma. However, the response rates remain low. To improve their efficacy, they should be combined with antigen-specific immunotherapy. Elevated expression of the transcription factor, Forkhead box M1 (FOXM1), has been reported in various human cancers, and it has been shown to have potential as a target for immunotherapy. The purpose of this study was to investigate the FOXM1 expression in human melanoma samples and cell lines, to evaluate the relationship between the FOXM1 expression and the clinical features of melanoma patients and to investigate the association between the FOXM1 and MAPK and PI3K/AKT pathways in melanoma cell lines. We conducted the quantitative reverse transcription PCR (qRT-PCR) and Western blotting analyses of melanoma cell lines, and investigated melanoma and nevus tissue samples by qRT-PCR and immunohistochemistry. We performed MEK siRNA and PI3K/AKT inhibitor studies and FOXM1 siRNA studies in melanoma cell lines. We found that FOXM1 was expressed in all of the melanoma cell lines, and was expressed in 49% of primary melanomas, 67% of metastatic melanomas and 10% of nevi by performing immunohistochemical staining. Metastatic melanoma samples exhibited significantly higher mRNA levels of FOXM1 (p = 0.004). Primary melanomas thicker than 2 mm were also more likely to express FOXM1. Patients whose primary melanoma expressed FOXM1 had a significantly poorer overall survival compared to patients without FOXM1 expression (p = 0.024). Downregulation of FOXM1 by siRNA significantly inhibited the proliferation of melanoma cells, and blockade of the MAPK and PI3K/AKT pathways decreased the FOXM1 expression in melanoma cell lines. In conclusion, FOXM1 is considered to be a new therapeutic target for melanoma.",
"The receptors of Notch family play an important role in controlling the development, differentiation, and function of multiple cell types. The aim of this study is to investigate the role of Notch1 signaling upon immune suppression induced by melanoma cells. Melanoma cell line B16 cells were transfected by lentivirus containing mouse Notch1 gene or Notch1 shRNA to generate B16 cell line that highly or lowly expressed Notch1. Notch1 in anti-tumor immune response was comprehensively appraised in murine B16 melanoma tumor model in immunocompetent and immunodeficient mice. The ratios of CD3+CD8+ cytotoxic T cells, CD49b+NK cells, CD4+CD25+FoxP3+ Tregs and Gr1+CD11b+ MDSCs in tumor-DLN or spleen were examined by flow cytometry. After the co-culture of B16 cells and CD8+ T cells, the effects of Notch1 on the proliferation and activation of T cells were assessed by CCK8 assay, CFSE dilution and Chromium-release test. The mRNA expression and supernatant secretion of immunosuppressive cytokines, TGF-β1, VEGF, IL-10 and IFN-γ were measured by RT-PCR and ELISA, respectively. Downregulation or overexpression of Notch1 in B16 melanoma cells inhibited or promoted tumor growth in immunocompetent mice, respectively. Notch1 expression in B16 melanoma cells inhibited the infiltration of CD8+ cytotoxic T lymphocytes and NK cells and reduced IFN-γ release in tumor tissue. It could also enhance B16 cell-mediated inhibition of T cell proliferation and activation, and upregulate PD-1 expression on CD4+ and CD8+ T cells. The percentage of CD4+CD25+FoxP3+ Tregs and Gr1+CD11b+MDSCs were significantly increased in tumor microenvironment, and all these were attributed to the upregulation of TGF-β1. These findings suggested that Notch1 signaling in B16 melanoma cells might inhibit antitumor immunity by upregulation of TGF-β1.",
"Nivolumab (a programmed death 1 [PD-1] checkpoint inhibitor) and ipilimumab (a cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4] checkpoint inhibitor) have been shown to have complementary activity in metastatic melanoma. In this randomized, double-blind, phase 3 study, nivolumab alone or nivolumab plus ipilimumab was compared with ipilimumab alone in patients with metastatic melanoma. We assigned, in a 1:1:1 ratio, 945 previously untreated patients with unresectable stage III or IV melanoma to nivolumab alone, nivolumab plus ipilimumab, or ipilimumab alone. Progression-free survival and overall survival were coprimary end points. Results regarding progression-free survival are presented here. The median progression-free survival was 11.5 months (95% confidence interval [CI], 8.9 to 16.7) with nivolumab plus ipilimumab, as compared with 2.9 months (95% CI, 2.8 to 3.4) with ipilimumab (hazard ratio for death or disease progression, 0.42; 99.5% CI, 0.31 to 0.57; P<0.001), and 6.9 months (95% CI, 4.3 to 9.5) with nivolumab (hazard ratio for the comparison with ipilimumab, 0.57; 99.5% CI, 0.43 to 0.76; P<0.001). In patients with tumors positive for the PD-1 ligand (PD-L1), the median progression-free survival was 14.0 months in the nivolumab-plus-ipilimumab group and in the nivolumab group, but in patients with PD-L1-negative tumors, progression-free survival was longer with the combination therapy than with nivolumab alone (11.2 months [95% CI, 8.0 to not reached] vs. 5.3 months [95% CI, 2.8 to 7.1]). Treatment-related adverse events of grade 3 or 4 occurred in 16.3% of the patients in the nivolumab group, 55.0% of those in the nivolumab-plus-ipilimumab group, and 27.3% of those in the ipilimumab group. Among previously untreated patients with metastatic melanoma, nivolumab alone or combined with ipilimumab resulted in significantly longer progression-free survival than ipilimumab alone. In patients with PD-L1-negative tumors, the combination of PD-1 and CTLA-4 blockade was more effective than either agent alone. (Funded by Bristol-Myers Squibb; CheckMate 067 ClinicalTrials.gov number, NCT01844505.).",
"Forkhead box (FOX) proteins have been shown to play important roles in regulating the expression of genes involved in cell growth, proliferation, differentiation, longevity, and transformation. The functional importance of this gene family in normal human skin physiology and disease processes is not well understood. Activation of Sonic Hedgehog (Shh) signaling plays a key role in the development of basal cell carcinomas (BCCs) of the skin in humans. Recent studies have established that some FOX genes are downstream targets of Shh signaling. We have investigated the role of FOX proteins in transducing Shh effects in human skin by using degenerate PCR to identify FOX genes differentially expressed in BCCs. All three known FOXM1 isoforms (a, b, and c) were detected in human skin and cultured keratinocytes, and the transcriptionally active FOXM1b isoform was found to be up-regulated in BCCs. Real-time quantitative RT-PCR showed that the increase in FOXM1 mRNA levels was specific for BCCs and not a reflection of increased cell proliferation in that no up-regulation was seen in squamous cell carcinomas or proliferating primary human keratinocyte cultures. Immunostaining studies showed intense nuclear and cytoplasmic staining throughout BCC tumor islands and not confined to the periphery regions of the tumor where proliferating Ki-67-immunopositive cells are predominantly localized. Expression of the Shh target glioma transcription factor-1 (Gli1) in primary keratinocytes and other cell lines caused a significant elevation of FOXM1 mRNA level and transcriptional activity, indicating that FOXM1 is a downstream target of Gli1. Our data provide the first evidence that activation of Shh signaling via Gli1 is an important determinant of FOXM1 expression in mammalian cells. Given the role of FOXM1 in cell proliferation, the up-regulation of FOXM1 in BCCs may be one of the mechanisms whereby Shh signaling exerts its mitogenic effect on basal keratinocytes, leading to the development of this common human cancer.",
"To provide a more precise estimate of long-term survival observed for ipilimumab-treated patients with advanced melanoma, we performed a pooled analysis of overall survival (OS) data from multiple studies. The primary analysis pooled OS data for 1,861 patients from 10 prospective and two retrospective studies of ipilimumab, including two phase III trials. Patients were previously treated (n = 1,257) or treatment naive (n = 604), and the majority of patients received ipilimumab 3 mg/kg (n = 965) or 10 mg/kg (n = 706). We also conducted a secondary analysis of OS data (n = 4,846) with an additional 2,985 patients from an expanded access program. OS rates were estimated using the Kaplan-Meier method. Among 1,861 patients, median OS was 11.4 months (95% CI, 10.7 to 12.1 months), which included 254 patients with at least 3 years of survival follow-up. The survival curve began to plateau around year 3, with follow-up of up to 10 years. Three-year survival rates were 22%, 26%, and 20% for all patients, treatment-naive patients, and previously treated patients, respectively. Including data from the expanded access program, median OS was 9.5 months (95% CI, 9.0 to 10.0 months), with a plateau at 21% in the survival curve beginning around year 3. To our knowledge, this is the largest analysis of OS to date for ipilimumab-treated patients with advanced melanoma. We observed a plateau in the survival curve, beginning at approximately 3 years, which was independent of prior therapy or ipilimumab dose. These data add to the evidence supporting the durability of long-term survival in ipilimumab-treated patients with advanced melanoma."
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Wilms' tumor gene on X chromosome inhibits epithelial-mesenchymal transition and migration of gastric cancer cells
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The aim of the present study was to investigate whether the expression of Wilms' tumor gene on X chromosome (WTX) affected the epithelial-mesenchymal transition (EMT) process and migration of gastric cancer cells. Stable WTX-overexpressing AGS cells (AGS.W) were established and analyzed by flow cytometry. The efficiency of the overexpression was verified by fluorescence microscopy, reverse transcription-quantitative polymerase chain reaction and western blotting. To analyze the expression of EMT-associated proteins, western blotting and immunofluorescence assays were performed. The migratory capability of the cells was detected by Transwell wound-healing assays, respectively. Compared with that of the control cells (AGS.veh), WTX expression was notably increased at mRNA (P<0.05) and protein levels (P<0.05) in the AGS.W gastric cancer cells. Morphological observations indicated that AGS.W cells transformed into spindle shapes, compared to AGS.veh cells, which maintained round or oval shapes. Furthermore, western blotting and immunofluorescence validated that the expression level of the epithelial marker epithelial-cadherin was significantly increased, whereas the expression levels of the mesenchymal markers neural-cadherin, β-catenin and vimentin were significantly decreased in the AGS.W cells compared with those in the AGS.veh cells. In addition, the overexpression of WTX decreased the migratory ability of AGS.W cells compared with AGS.veh cells. Exogenous expression of WTX inhibited gastric cancer cell migration by reversing EMT. The results of the present study describe a molecular feature that may be a promising target for future gastric cancer therapy strategies.
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"CircRNAs are a class of endogenous RNA that regulates gene expression at the post-transcriptional or transcriptionallevel through interacting with other molecules or microRNAs. Increasing studies have demonstrated that circRNAs play a crucial role in biology processes. CircRNAs are proved as potentialbiomarkers in many diseases including cancers. However, the role of Cdr1as in Hepatocellular carcinoma (HCC) remains to be elucidated. We demonstrated that Cdr1as expression was upregulated in HCC tissues compared with the adjacent non-tumor tissues. In addtion, miR-7 expression was downregulated in HCC tissues compared with the adjacent non-tumor tissues. Moreover, the expression level of miR-7 was inversely correlated with that in HCC tissues. Knockdown of Cdr1as suppressed the HCC cell proliferation and invasion. Overexpression of miR-7 inhibited the HCC cell proliferation and invasion. Overexpression of miR-7 could suppress the direct target gene CCNE1 and PIK3CD expression. Knockdown of Cdr1as suppressed the expression of miR-7 and also inhibited the CCNE1 and PIK3CD expression. Furthermore, knockdown of Cdr1as suppressed the HCC cell proliferation and invasion through targeting miR-7. These data suggested that Cdr1as acted as an oncogene partly through targeting miR-7 in HCC.",
"Circular RNAs are a large class of noncoding RNA that have shown huge capabilities as gene regulators. Recent evidence suggest that circular RNAs are associated with many diseases, especially cancer. However, little attention has been focused on the expression and function of circular RNA in gastric cancer (GC). In this study, we demonstrate that the expression of circ-104916 is downregulated in GC tissues and cell lines. A lower expression of circ-104916 appeared in deeper invasion depth, higher tumor stage and more frequent lymphatic metastasis patients. Overexpression of circ-104916 effectively inhibited the proliferation, migration and invasion abilities of GC cells in vitro. Western blot showed that circ-104916 overexpression upregulated E-cadherin and downregulated N-cadherin, Vimentin and Slug, indicating that circ-104916 was involved in the epithelial-mesenchymal transition process. Our results revealed that circ-104916 might be a novel potential tumor suppressor and biomarker of GC.",
"Epithelial to mesenchymal transition (EMT) is essential for driving plasticity during development, but is an unintentional behaviour of cells during cancer progression. The EMT-associated reprogramming of cells not only suggests that fundamental changes may occur to several regulatory networks but also that an intimate interplay exists between them. Disturbance of a controlled epithelial balance is triggered by altering several layers of regulation, including the transcriptional and translational machinery, expression of non-coding RNAs, alternative splicing and protein stability.",
"Tumor recurrence is usually detected within one year after radical resection of stage III gastric cancer. This study aimed to establish the expression profile and determine potential circular RNAs (circRNAs) and predict the early recurrence of stage III gastric cancer. We identified 46 differently expressed circRNAs between cancer and adjacent normal tissues through circRNA microarray. We further screened eight indicators related to early recurrence. We subsequently divided the remaining cases into two cohorts. qRT-PCR results demonstrated a significantly different outcome between low and high expressed groups of four circRNAs in the training cohort. We then constructed a four-circRNA-based classifier to evaluate the risk of early recurrence and distinguished patients with a high risk from those with a low risk. The areas under the receiver operator characteristic curve (ROC) of this classifier were 0.763 and 0.711 in the two cohorts, respectively. A new formula could be established by combined the circRNA classifier with TNM stages. The areas under the ROC curve were 0.866 and 0.818 of the two cohorts, respectively. Our study suggested that this four-circRNA-based classifier yielded a predictive ability to the early recurrence of stage III gastric cancer after radical surgery.",
"There is increasing evidence that circular RNAs (circRNAs) are involved in cancer development; however, their role in hepatocellular carcinoma (HCC) remains unclear. Here, we aimed to determine the circRNA expression profile in HCC, and investigate relevant mechanisms for cancer progression. The global circRNA expression profile between HCC (n = 3) and adjacent normal liver (n = 3) tissue was significantly different. Three circRNAs (hsa_circ_0000520, hsa_circ_0005075, and hsa_circ_0066444) showed significantly different expression levels in HCC tissues, which were further validated in 60 matched tissue samples using real-time qRT-PCR. Only hsa_circ_0005075 exhibited significant difference in expression (P <0.001) between HCC and normal tissues. Hsa_circ_0005075 expression correlated with HCC tumor size (P = 0.042), and showed good diagnostic potential (AUROC = 0.94). Finally, we constructed a network of hsa_circ_0005075-targeted miRNA-gene interactions, including miR-23b-5p, miR-93-3p, miR-581, miR-23a-5p, and their corresponding mRNAs. Gene oncology analysis revealed that hsa_circ_0005075 could participate in cell adhesion during HCC development. In summary, we identified hsa_circ_0005075 as a potential HCC biomarker; however, further studies are required to confirm the role of this circRNA, and others, in HCC development."
] |
Preoperative platelet-lymphocyte ratio and neutrophil-lymphocyte ratio as prognostic factors in curative resected ampullary carcinoma
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The objective of the present study was to evaluate whether preoperative platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) could predict the prognosis for curative resected ampullary carcinoma. A total of 94 patients were retrospectively included over a 6-year period in which consecutive cases underwent pancreaticoduodenectomy for ampullary malignancy. Preoperative blood results were available in the 94 cases of resected ampullary carcinoma. Preoperative PLR and NLR cut-off values of 226.8 and 2.58 were determined to represent the optimal cut-off values in the cases for survival analysis. PLR remained a significant independent predictor of survival in multivariate analysis (Cox, P<0.001) in addition to tumor differentiation (P<0.001), nodal status (P<0.001) and stage (P<0.001). While NLR failed to serve as a prognostic factor in univariate (P=0.0637) and multivariate (P=0.164) survival analysis. Furthermore, the nodal involvement rate was higher in high PLR group (74.2 vs. 19.05%, P<0.001). Preoperative PLR and NLR merit further evaluation as a prognostic index in curative resected ampullary carcinoma. Additionally, it is a candidate predictor for the lymph node metastasis.
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[
"Not all patients respond equally to neoadjuvant chemoradiotherapy (nCRT), with subsequent effects on survival. The systemic inflammatory response has been shown to predict long-term outcomes in colorectal cancer. The current study examined the association between systemic inflammation and nCRT in patients with rectal cancer. Between 1999 and 2010, patients who underwent nCRT were identified. Serum measurements of hemoglobin, C-reactive protein, albumin, modified Glasgow prognostic score (mGPS), and differential white cell counts were obtained before and after nCRT. The Rödel scoring system measured pathologic tumor regression, and magnetic resonance imaging and computed tomography determined radiologic staging. The study included 79 patients. Of these patients, 37% were radiologically downstaged, and 44% were categorized as showing a good pathologic response (Rödel scores 3 and 4). As a validated measure of the systemic inflammatory response, mGPS (P = 0.022) was associated with a poor pathologic response to nCRT. A radiologic response was associated with a good pathologic response to treatment (P = 0.003). A binary logistic regression model identified mGPS (odds ratio [OR] 0.27; 95% confidence interval [CI] 0.07-0.96; P = 0.043) and radiologic response (OR 0.43; 95% CI 0.18-0.99; P = 0.048) as strong independent predictors of a pathologic response to treatment. The current study showed that a systemic inflammatory response before nCRT is associated with a poor pathologic response. Further study in a prospective controlled trial setting is warranted.",
"Cancer-associated inflammation has been identified as a key determinant of disease progression and survival in colorectal cancer. In particular, it has been consistently reported that both the local and systemic inflammatory responses play an important role in determining outcome in colorectal cancer. Given the importance of cancer-associated inflammation, up-regulation or attenuation of these respective inflammatory responses may be important for progression and survival in colorectal cancer. Recent work has focused on the inter-relationships between the tumour and these key inflammatory processes. In particular, tumour necrosis has been reported to be associated with decreased local inflammatory infiltrate and with elevated markers of systemic inflammation in colorectal cancer and has been proposed as a potential link between the systemic and local inflammatory responses. Thus there is increasing interest in the potential biochemical mediators of this link. In this review we examine the evidence for IL-6 in the natural history of colorectal cancer and its relationship with tumour necrosis and the local and systemic inflammatory responses. There is now good evidence that tumour concentrations of IL-6 have been directly associated with increased necrosis, proliferation, differentiation and vascular invasion, while circulating concentrations of IL-6 are directly associated with T-stage, CRP concentrations and poorer survival. Also, interleukin-6 and down-stream pathways, such as the JAK/STAT pathway, have emerged as important factors in the modulation of cancer-associated inflammation. Therefore, IL-6 has emerged as a key mediator of the relationship between tumour necrosis, local and systemic inflammatory responses and outcome in patients with colorectal cancer.",
"Peritoneal elicited macrophages (PEM) from mammary tumor-bearing mice have a decreased capacity to become cytotoxic against syngeneic, allogeneic, and xenogeneic target cells upon in vitro stimulation with LPS, as compared with PEM of normal mice. A regulatory mechanism other than PG release is suggested because the addition of both indomethacin and LPS to macrophage cultures from tumor-bearing mice caused no changes in their cytotoxic capability. Because tumor products have been implicated in the down-regulation of immune responses, we investigated whether pretreatment with supernatants from the tumor cell line DA-3, derived from the in vivo mammary adenocarcinoma D1-DMBA-3, affects the cytolytic capacity of macrophages. This treatment inhibits, in a dose-dependent fashion, the ability of stimulated normal PEM to kill target cells. Partial purification of DA-3 cell line supernatant showed that most of the inhibitory activity was exerted by factors with a molecular mass greater than 10 kDa and less than 30 kDa. However, slight inhibition could also be observed with fractions containing molecules less than 10 kDa. The data suggest that more than one factor released by the mammary tumor cells may be involved in the down-regulation of macrophage-mediated cytotoxicity. Because the DA-3 cells constitutively produce granulocyte-macrophage CSF (GM-CSF), which has a molecular mass of 27 kDa, we pretreated PEM from normal mice in vitro with rGM-CSF for 24 h. This resulted in a dose-dependent decrease in their capacity to kill tumor target cells upon LPS stimulation. Furthermore, PEM from normal mice injected with rGM-CSF for 25 days displayed a profound decrease in their cytolytic ability against DA-3 targets upon in vitro stimulation with increasing amounts of LPS. The pretreatment of PEM from normal mice with a combination of DA-3 cell supernatants and specific anti-GM-CSF partially neutralized the inhibitory effect of the DA-3 supernatant on macrophage tumoricidal capability. These results indicate that tumor-derived GM-CSF is an important factor involved in the decreased macrophage cytotoxicity during mammary adenocarcinoma progression.",
"Despite advances in preoperative radiologic imaging, a significant fraction of potentially resectable pancreatic cancers are found to be unresectable at laparotomy. We tested the hypothesis that preoperative serum levels of CA19-9 (cancer antigen) and carcinoembryonic antigen will identify patients with unresectable pancreatic cancer despite radiologic staging demonstrating resectable disease. Academic tertiary care referral center. From March 1, 1996, to July 31, 2002, 125 patients were identified who underwent surgical exploration for potentially resectable pancreatic cancer based on a preoperative computed tomographic scan; in 89 of them a preoperative tumor marker had been measured. Preoperative tumor markers (CA19-9 and carcinoembryonic antigen) were correlated with extent of disease at exploration. As CA19-9 is excreted in the biliary system, CA19-9 adjusted for the degree of hyperbilirubinemia was determined and analyzed. Of the 89 patients, 40 (45%) had localized disease and underwent resection, 25 (28%) had locally advanced (unresectable) disease, and 24 (27%) had metastatic disease. The mean adjusted CA19-9 level was significantly lower in those with localized disease than those with locally advanced (63 vs 592; P =.003) or metastatic (63 vs 1387; P<.001) disease. When a threshold adjusted CA19-9 level of 150 was used, the positive predictive value for determination of unresectable disease was 88%. Carcinoembryonic antigen level was not correlated with extent of disease. Among the patients with resectable pancreatic cancer based on preoperative imaging studies, those with abnormally high serum levels of CA19-9 may have unresectable disease. These patients may benefit from additional staging modalities such as diagnostic laparoscopy to avoid unnecessary laparotomy.",
"We assessed the impact of tumor regression grading (TRG) and its value in correlation to established prognostic factors in a cohort of rectal carcinoma patients treated by preoperative chemoradiotherapy (CRT). TRG was evaluated on surgical specimens of 385 patients treated within the preoperative CRT arm of the CAO/ARO/AIO-94 trial: 50.4 Gy was delivered, fluorouracil was given in the first and fifth week, and surgery was performed 6 weeks thereafter. TRG was determined by the amount of viable tumor versus fibrosis, ranging from TRG 4 when no viable tumor cells were detected, to TRG 0 when fibrosis was completely absent. TRG 3 was defined as regression more than 50% with fibrosis outgrowing the tumor mass, TRG 2 was defined as regression less than 50%, and TRG 1 was defined basically as a morphologically unaltered tumor mass. We performed an initially unplanned, hypothesis-generating analysis with respect to the prognostic value of this TRG system. TRG 4, 3, 2, 1, 0 was found in 10.4%, 52.2%, 13.8%, 15.3%, and 8.3% of the resected specimens, respectively. Five-year disease-free survival (DFS) after CRT and curative resection was 86% for TRG 4, 75% for grouped TRG 2 + 3, and 63% for grouped TRG 0 + 1 (P = .006). On multivariate analysis, the pathologic T category and the nodal status after CRT were the most important independent prognostic factors for DFS. In this exploratory analysis, complete (TRG 4) and intermediate pathologic response (TRG 2 + 3) suggested improved DFS after preoperative CRT. TRG assessment should be implemented in pathologic evaluation and prospectively validated in further studies.",
"Determinants of cancer progression and survival are multifactorial and host responses are increasingly appreciated to have a major role. Indeed, the development and maintenance of a systemic inflammatory response has been consistently observed to confer poorer outcome, in both early and advanced stage disease. For patients, cancer-associated symptoms are of particular importance resulting in a marked impact on day-to-day quality of life and are also associated with poorer outcome. These symptoms are now recognised to cluster with one another with anorexia, weight loss and physical function forming a recognised cluster whereas fatigue, pain and depression forming another. Importantly, it has become apparent that these symptom clusters are associated with presence of a systemic inflammatory response in the patient with cancer. Given the understanding of the above, there is now a need to intervene to moderate systemic inflammatory responses, where present. In this context the rationale for therapeutic intervention using nonselective anti-inflammatory agents is clear and compelling and likely to become a part of routine clinical practice in the near future. The published literature on therapeutic intervention using anti-inflammatory agents for cancer-associated symptoms was reviewed. There are important parallels with the development of useful treatments for the systemic inflammatory response in patients with rheumatological disease and cardiovascular disease.",
"Chronic noncommunicable diseases (CNCDs), which include cardiovascular disease, some cancers, for example, colon cancer, breast cancer, and type 2 diabetes, are reaching epidemic proportions worldwide. It has now become clear that low-grade chronic inflammation is a key player in the pathogenesis of most CNCDs. Given that regular exercise offers protection against all causes of mortality, primarily by protection against atherosclerosis and insulin resistance, we suggest that exercise may exert some of its beneficial health effects by inducing anti-inflammatory actions. Recently, IL-6 was introduced as the first myokine, defined as a cytokine, which is produced and released by contracting skeletal muscle fibres, exerting its effects in other organs of the body. We suggest that skeletal muscle is an endocrine organ and that myokines may be involved in mediating the beneficial effects against CNCDs associated with low-grade inflammation."
] |
[Porcine transmissible gastroenteritis virus (TGEV) in neonatal diarrhea].
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In 2014, a notification of porcine transmissible gastroenteritis virus (TGEV) was made by the National Services of Animal Health of Argentina (SENASA) to the World Organization of Animal Health (OIE). The notification was based on a serological diagnosis in a small farm with a morbidity rate of 2.3% without enteric clinical signs. In order to determine if TGEV was circulating before the official report, a retrospective study on cases of neonatal diarrhea was performed. The selection criteria was a sudden increase in mortality in 1- to 21-day-old piglets with watery diarrhea that did not respond to antibiotics. Based on these criteria, three clinical cases were identified during 2010-2015.
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[
"Porcine deltacoronavirus (PDCoV) was first identified in Hong Kong in 2009-2010 and reported in United States swine for the first time in February 2014. However, diagnostic tools other than polymerase chain reaction for PDCoV detection were lacking and Koch's postulates had not been fulfilled to confirm the pathogenic potential of PDCoV. In the present study, PDCoV peptide-specific rabbit antisera were developed and used in immunofluorescence and immunohistochemistry assays to assist PDCoV diagnostics. The pathogenicity and pathogenesis of PDCoV was investigated following orogastric inoculation of 5-day-old piglets with a plaque-purified PDCoV cell culture isolate (3 × 10(4) TCID50 per pig). The PDCoV-inoculated piglets developed mild to moderate diarrhea, shed increasing amount of virus in rectal swabs from 2 to 7 days post inoculation, and developed macroscopic and microscopic lesions in small intestines with viral antigen confirmed by immunohistochemistry staining. This study experimentally confirmed PDCoV pathogenicity and characterized PDCoV pathogenesis in neonatal piglets.",
"Porcine epidemic diarrhea virus (PEDV), a member of the genera Alphacoronavirus in the family Coronaviridae, causes acute diarrhea/vomiting, dehydration and high mortality in seronegative neonatal piglets. For the last three decades, PEDV infection has resulted in significant economic losses in the European and Asian pig industries, but in 2013-2014 the disease was also reported in the US, Canada and Mexico. The PED epidemic in the US, from April 2013 to the present, has led to the loss of more than 10% of the US pig population. The disappearance and re-emergence of epidemic PED indicates that the virus is able to escape from current vaccination protocols, biosecurity and control systems. Endemic PED is a significant problem, which is exacerbated by the emergence (or potential importation) of multiple PEDV variants. Epidemic PEDV strains spread rapidly and cause a high number of pig deaths. These strains are highly enteropathogenic and acutely infect villous epithelial cells of the entire small and large intestines although the jejunum and ileum are the primary sites. PEDV infections cause acute, severe atrophic enteritis accompanied by viremia that leads to profound diarrhea and vomiting, followed by extensive dehydration, which is the major cause of death in nursing piglets. A comprehensive understanding of the pathogenic characteristics of epidemic or endemic PEDV strains is needed to prevent and control the disease in affected regions and to develop an effective vaccine. This review focuses on the etiology, epidemiology, disease mechanisms and pathogenesis as well as immunoprophylaxis against PEDV infection.",
"Porcine deltacoronavirus (PDCoV) was detected in feces from diarrheic sows during an epidemic of acute and transmissible diarrhea. No transmissible gastroenteritis virus or porcine epidemic diarrhea virus was detected. The PDCoV USA/IA/2014/8734 from the herd was sequenced for full-length genomic RNA to further characterize PDCoV in U.S. swine.",
"To investigate the causative agent of swine diarrhea, next-generation sequencing (NGS) was performed on a porcine fecal sample. The NGS reads were assembled, which generated a complete swine Deltacoronavirus genome sequence, that of strain SDCV/USA/Illinois121/2014.",
"Eighty-four colostrum-deprived piglets aged 1 day were inoculated with either a Korean strain of transmissible gastroenteritis virus (TGEV) or one of two American strains (Purdue and Miller). The purpose was to compare, by morphometric analysis and in-situ hybridization, the Korean strain with the two American strains in respect of pathogenicity and viral distribution over a period of 72 h. The progression of infection in pigs infected with the Korean strain was much slower than that in pigs infected with either of the two American strains. At 6 h post-inoculation (hpi), the mean score of the villous height/crypt depth (VH/CD) ratio of pigs inoculated with the Purdue or Miller strain was significantly less than that of pigs inoculated with the Korean strain or uninfected control pigs. At 12-72 hpi, however, the VH/CD ratio of all infected pigs was significantly less than that of control pigs. In-situ hybridization showed significant differences between the Korean and American strains in terms of the amount of TGEV nucleic acid at 6, 12 and 60 hpi. TGEV nucleic acid was detected in the duodenum, jejunum and ileum of pigs inoculated with the Purdue or Miller strain but only in the jejunum and ileum of those inoculated with the Korean strain. The results suggested that the Korean strain was less virulent than the two American strains."
] |
RAS and BRAF ddPCR mutational testing for thyroid fine needle aspirate biopsy
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Recent guidelines for the management of thyroid nodules incorporate mutation testing as an adjunct for surgical decision-making, however current tests are costly with limited accuracy. Droplet digital PCR (ddPCR) is an ultrasensitive method of nucleic acid detection that is particularly useful for identifying gene mutations. This study aimed to assess the analytic and clinical validity of RAS and BRAF ddPCR mutational testing as a diagnostic tool for thyroid fine needle aspirate biopsy (FNAB).
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[
"The authors review anatomical, clinical characteristics and prevalence of thyroid microcarcinoma. Diagnostic procedures and risk factors of aggressiveness at diagnosis and during follow-up are also covered. The possible clinical, pathologic and therapeutic risk factors are analyzed by meta-analysis study. Treatment procedures by different authors and guidelines suggested by societies are reported.",
"Genetic alteration is the driving force for thyroid tumorigenesis and progression, based upon which novel approaches to the management of thyroid cancer can be developed. A recent important genetic finding in thyroid cancer is the oncogenic T1799A transversion mutation of BRAF (the gene for the B-type Raf kinase, BRAF). Since the initial report of this mutation in thyroid cancer 2 years ago, rapid advancements have been made. BRAF mutation is the most common genetic alteration in thyroid cancer, occurring in about 45% of sporadic papillary thyroid cancers (PTCs), particularly in the relatively aggressive subtypes, such as the tall-cell PTC. This mutation is mutually exclusive with other common genetic alterations, supporting its independent oncogenic role, as demonstrated by transgenic mouse studies that showed BRAF mutation-initiated development of PTC and its transition to anaplastic thyroid cancer. BRAF mutation is mutually exclusive with RET/PTC rearrangement, and also displays a reciprocal age association with this common genetic alteration in thyroid cancer. The T1799A BRAF mutation occurs exclusively in PTC and PTC-derived anaplastic thyroid cancer and is a specific diagnostic marker for this cancer when identified in cytological and histological specimens. This mutation is associated with a poorer clinicopathological outcome and is a novel independent molecular prognostic marker in the risk evaluation of thyroid cancer. Moreover, preclinical and clinical evaluations of the therapeutic value of novel specific mitogen-activated protein kinase pathway inhibitors in thyroid cancer are anticipated. This newly discovered BRAF mutation may prove to have an important impact on thyroid cancer in the clinic.",
"The B-Raf proto-oncogene serine/threonine kinase (BRAF)V600E mutation is an important oncogene in the development of papillary thyroid carcinoma (PTC) and has been identified as a risk factor for poor prognosis in patients with PTC. However, whether the BRAFV600E mutation is a prognostic marker in patients with solitary papillary thyroid microcarcinoma (sPTMC) has not yet been established. The present study aimed to identify the association between BRAFV600E mutation and the clinicopathological features of patients with sPTMC. A total of 108 patients with sPTMC who underwent surgery at the Cancer Institute and Hospital of the Chinese Academy of Medical Sciences between December 2010 and December 2012 were analyzed retrospectively. Exon 15 of the BRAF gene was amplified using the polymerase chain reaction and direct sequencing was performed to detect the BRAFV600E mutation. Statistical analysis was subsequently performed using SPSS software (version 16.0). The association between BRAFV600E mutation and clinicopathological features of sPTMC was tested with the χ2 test or Fisher's exact test, as appropriate. There were 27 males and 81 females in the cohort, who were aged between 22 and 66 years old, with an average age of 42 years. The BRAFV600E mutation was found in 59 out of 108 (54.6%) patients with sPTMC. The presence of the BRAFV600E mutation was demonstrated to be significantly associated with extrathyroidal extension (P=0.019), advanced Tumor-Node-Metastasis stage (P=0.007) and the presence of autoimmune thyroiditis (P=0.010). The BRAFV600E mutation was not significantly associated with gender, anatomic location or subtype of sPTMC (P>0.05). In addition, the BRAFV600E mutation indicated poor prognosis in patients with sPTMC. These results suggest that the BRAFV600E mutation is a risk factor for poor prognosis in patients with sPTMC. This knowledge will aid in the risk stratification and post-operative management of patients with sPTMC."
] |
PredHS2: Predicting Hot Spots at Protein-Protein Interfaces
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Identification of hot spots, a small portion of protein-protein interface residues that contribute the majority of the binding free energy, can provide crucial information for understanding the function of proteins and studying their interactions. Based on our previous method (PredHS), we propose a new computational approach, PredHS2, that can further improve the accuracy of predicting hot spots at protein-protein interfaces. Firstly we build a new training dataset of 313 alanine-mutated interface residues extracted from 34 protein complexes. Then we generate a wide variety of 600 sequence, structure, exposure and energy features, together with Euclidean and Voronoi neighborhood properties. To remove redundant and irrelevant information, we select a set of 26 optimal features utilizing a two-step feature selection method, which consist of a minimum Redundancy Maximum Relevance (mRMR) procedure and a sequential forward selection process. Based on the selected 26 features, we use Extreme Gradient Boosting (XGBoost) to build our prediction model. Performance of our PredHS2 approach outperforms other machine learning algorithms and other state-of-the-art hot spot prediction methods on the training dataset and the independent test set (BID) respectively. Several novel features, such as solvent exposure characteristics, second structure features and disorder scores, are found to be more effective in discriminating hot spots. Moreover, the update of the training dataset and the new feature selection and classification algorithms play a vital role in improving the prediction quality.
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[
"Hot spots are interface residues that contribute most binding affinity to protein-protein interaction. A compact and relevant feature subset is important for building machine learning methods to predict hot spots on protein-protein interfaces. Although different methods have been used to detect the relevant feature subset from a variety of features related to interface residues, it is still a challenge to detect the optimal feature subset for building the final model. In this study, three different feature selection methods were compared to propose a new hybrid feature selection strategy. This new strategy was proved to effectively reduce the feature space when we were building the prediction models for identifying hotspot residues. It was tested on eighty-two features, both conventional and newly proposed. According to the strategy, combining the feature subsets selected by decision tree and mRMR (maximum Relevance Minimum Redundancy) individually, we were able to build a model with 6 features by using a PSFS (Pseudo Sequential Forward Selection) process. Compared with other state-of-art methods for the independent test set, our model had shown better or comparable predictive performances (with F-measure 0.622 and recall 0.821). Analysis of the 6 features confirmed that our newly proposed feature CNSV_REL1 was important for our model. The analysis also showed that the complementarity between features should be considered as an important aspect when conducting the feature selection. In this study, most important of all, a new strategy for feature selection was proposed and proved to be effective in selecting the optimal feature subset for building prediction models, which can be used to predict hot spot residues on protein-protein interfaces. Moreover, two aspects, the generalization of the single feature and the complementarity between features, were proved to be of great importance and should be considered in feature selection methods. Finally, our newly proposed feature CNSV_REL1 had been proved an alternative and effective feature in predicting hot spots by our study. Our model is available for users through a webserver: http://zhulab.ahu.edu.cn/iPPHOT/ .",
"The KFC Server is a web-based implementation of the KFC (Knowledge-based FADE and Contacts) model-a machine learning approach for the prediction of binding hot spots, or the subset of residues that account for most of a protein interface's; binding free energy. The server facilitates the automated analysis of a user submitted protein-protein or protein-DNA interface and the visualization of its hot spot predictions. For each residue in the interface, the KFC Server characterizes its local structural environment, compares that environment to the environments of experimentally determined hot spots and predicts if the interface residue is a hot spot. After the computational analysis, the user can visualize the results using an interactive job viewer able to quickly highlight predicted hot spots and surrounding structural features within the protein structure. The KFC Server is accessible at http://kfc.mitchell-lab.org.",
"Protein-protein interactions are key components of all signal transduction processes, so methods to alter these interactions promise to become important tools in dissecting function of connectivities in these networks. We have developed a fast computational approach for the prediction of energetically important amino acid residues in protein-protein interfaces (available at http://robetta.bakerlab.org/alaninescan), which we, following Peter Kollman, have termed \"computational alanine scanning.\" The input consists of a three-dimensional structure of a protein-protein complex; output is a list of \"hot spots,\" or amino acid side chains that are predicted to significantly destabilize the interface when mutated to alanine, analogous to the results of experimental alanine-scanning mutagenesis. 79% of hot spots and 68% of neutral residues were correctly predicted in a test of 233 mutations in 19 protein-protein complexes. A single interface can be analyzed in minutes. The computational methodology has been validated by the successful design of protein interfaces with new specificity and activity, and has yielded new insights into the mechanisms of receptor specificity and promiscuity in biological systems.",
"Binding of one protein to another is involved in nearly all biological functions, yet the principles governing the interaction of proteins are not fully understood. To analyze the contributions of individual amino acid residues in protein-protein binding we have compiled a database of 2325 alanine mutants for which the change in free energy of binding upon mutation to alanine has been measured (available at http://motorhead. ucsf.edu/thorn/hotspot). Our analysis shows that at the level of side-chains there is little correlation between buried surface area and free energy of binding. We find that the free energy of binding is not evenly distributed across interfaces; instead, there are hot spots of binding energy made up of a small subset of residues in the dimer interface. These hot spots are enriched in tryptophan, tyrosine and arginine, and are surrounded by energetically less important residues that most likely serve to occlude bulk solvent from the hot spot. Occlusion of solvent is found to be a necessary condition for highly energetic interactions.",
"We present SpotOn, a web server to identify and classify interfacial residues as Hot-Spots (HS) and Null-Spots (NS). SpotON implements a robust algorithm with a demonstrated accuracy of 0.95 and sensitivity of 0.98 on an independent test set. The predictor was developed using an ensemble machine learning approach with up-sampling of the minor class. It was trained on 53 complexes using various features, based on both protein 3D structure and sequence. The SpotOn web interface is freely available at: http://milou.science.uu.nl/services/SPOTON/ .",
"Empirical models for the prediction of how changes in sequence alter protein-protein binding kinetics and thermodynamics can garner insights into many aspects of molecular biology. However, such models require empirical training data and proper validation before they can be widely applied. Previous databases contained few stabilizing mutations and no discussion of their inherent biases or how this impacts model construction or validation. We present SKEMPI, a database of 3047 binding free energy changes upon mutation assembled from the scientific literature, for protein-protein heterodimeric complexes with experimentally determined structures. This represents over four times more data than previously collected. Changes in 713 association and dissociation rates and 127 enthalpies and entropies were also recorded. The existence of biases towards specific mutations, residues, interfaces, proteins and protein families is discussed in the context of how the data can be used to construct predictive models. Finally, a cross-validation scheme is presented which is capable of estimating the efficacy of derived models on future data in which these biases are not present. The database is available online at http://life.bsc.es/pid/mutation_database/."
] |
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