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11589295 | On-line capillary electrophoresis-electrospray mass spectrometry for the stereoselective analysis of drugs and metabolites. | The on-line combination of partial-filling capillary electrophoresis and electrospray ionization mass spectrometry was demonstrated for the enantioseparation of pharmaceutical drugs and metabolites, namely amphetamines, methadone, venlafaxine and selected tropane alkaloids. The partial-filling technique proved to be a ... |
11589293 | Chiral separation of amino acid esters by micellar electrokinetic chromatography. | Micellar electrokinetic chromatography (MEKC) was used for the chiral separation of uncharged analytes (C- and N-protected amino acids). Sodium dodecyl sulfate (SDS) was the micelle forming agent, and different cyclodextrin (CD) derivatives were added as chiral selectors. Suitable conditions for the enantioseparation w... |
11589291 | Enantioseparation of the anticoagulant drug phenprocoumon in capillary electrophoresis with UV and laser-induced fluorescence detection and application of the method to urine samples. | The enantioseparation of phenprocoumon (PhC) in capillary electrophoresis (CE) has been studied using various cyclodextrins (CDs) such as native alpha, beta and gamma-CD and several neutral and randomly, as well as selectively substituted charged CD derivatives. Reversal of the enantiomer migration order was observed w... |
11589290 | Enantiomeric analysis of the five major monohydroxylated metabolites of methaqualone in human urine by chiral capillary electrophoresis. | Methaqualone (MQ; 2-methyl-3-o-tolylquinazolin-4(3H)-one) is a hypnotic and anticonvulsive drug in which the rotation about the nitrogen-to-aryl bond between the planar 2-methyl-quinazolin-4(3H)-one structure and the o-tolyl moiety is sterically hindered at body temperature. MQ and its five major monohydroxylated metab... |
11589289 | Enantioselective analysis of albendazole sulfoxide in cerebrospinal fluid by capillary electrophoresis. | Albendazole (ABZ) is a benzimidazole anthelmintic drug used in the treatment of neurocysticercosis. After oral administration, ABZ is rapidly oxidized to albendazole sulfoxide (ABZSO), which has an asymmetric sulfur center, and later to albendazole sulfone (ABZSO2). ABZSO is the active metabolite responsible for the th... |
11589286 | Evidences of cyclodextrin-mediated enantioselective photodegradation of rac-nicardipine by capillary electrophoresis. | Capillary electrophoresis (CE) was applied to photostability studies on rac-nicardipine, a dihydropyridine chiral drug. CE methods were developed able to provide the enantioresolution of drug and its separation from the photodegradation products. Enantioresolution was achieved using 5% sulfated-beta-cyclodextrin (S-bet... |
11589285 | Enantioseparation of chiral thiobarbiturates using cyclodextrin-modified capillary electrophoresis. | The racemates of several chiral thiobarbiturates were separated by using different cyclodextrins in capillary electrophoresis (CE). Six neutral and negatively charged cyclodextrins 1 (CDs) were employed as chiral separators whereof five led to successful separation of enantiomeric thiobarbiturate pairs. The CDs used we... |
11589284 | Chiral separation of pyrethroic acids with single isomer permethyl monoamino beta-cyclodextrin selector. | Enantiomers and diastereomers of chrysanthemic, permethrinic, and deltamethrinic pyrethroic acids were separated from each other, using positively ionizable permethyl monoamino beta-cyclodextrin (PMMAbetaCD). The highest chiral resolution value was 20.0. The optimum conditions of separation were found to be 16 mM PMMAb... |
11589283 | Separation of ritalin racemate and its by-product racemates by capillary electrophoresis. | Ritalin, [(+)-threo]methylphenidate hydrochloride, is a chiral drug substance with two chiral centers. The drug substance may contain three pairs of enantiomers, [(+)-threo], [(-)-threo], [(+)-erythro] and [(-)-erythro] isomers, and its degradation products, threoritalinic acid racemate. Determination of the optical pu... |
11589282 | Enantiomeric separation of chiral phenoxy acid herbicides by electrokinetic chromatography. Application to the determination of analyte-selector apparent binding constants for enantiomers. | The enantiomeric resolution of chiral phenoxy acid herbicides was performed by electrokinetic chromatography using a cyclodextrin as chiral pseudophase (CD-EKC). A systematic evaluation of several neutral and charged cyclodextrins was made. Among the cyclodextrins tested, (2-hydroxy)propyl beta-cyclodextrin (HP-beta-CD... |
11589281 | Rapid screening for chiral separations by short-end injection capillary electrophoresis using highly sulfated cyclodextrins as chiral selectors. | Two series of amino acid derivatives and phenylamines were used to evaluate the potential of highly sulfated cyclodextrins (HS-CDs) for the screening for chiral separations by capillary electrophoresis (CE). HS-CDs showed to be very versatile and to exhibit very high enantioselectivity. The use of short-end injection a... |
11589280 | Chiral separation of pharmacologically active dihydropyrimidinones with carboxymethyl-beta-cyclodextrin. | We report on the chiral separation of pharmacologically active dihydropyrimidinones by capillary electrophoresis (CE) using carboxymethyl-beta-cyclodextrin as chiral selector. The influence of selector concentration, pH, and the addition of varying amounts of methanol is investigated. Out of 21 compounds investigated, ... |
11589279 | Fast enantiomeric separation of basis drugs by electrokinetic chromatography. Application to the quantitation of terbutaline in a pharmaceutical preparation. | Electrokinetic chromatography (EKC) using micelles of bile salts alone or mixed with sodium dodecyl sulfate (SDS) and neutral, anionic, or cationic cyclodextrins (CDs) in the separation buffer has been employed in order to achieve fast enantiomeric separation of basic drugs. A study of the enantiomeric separation abili... |
11589278 | Determination of the enantiomerization barrier of thalidomide by dynamic capillary electrokinetic chromatography. | Enantioselective chromatographic methods, representing the most commonly used techniques for the determination of enantiomeric ratios, can also be used for the evaluation of stereochemical integrity. In the present study, dynamic capillary electrokinetic chromatography (DEKC) was employed to determine the enantiomeriza... |
11589277 | Mechanistic study on the opposite migration order of clenbuterol enantiomers in capillary electrophoresis with beta-cyclodextrin and single-isomer heptakis(2,3-diacetyl-6-sulfo)-beta-cyclodextrin. | Opposite migration order was observed for the enantiomers of the chiral beta2-adrenergic drug clenbuterol (CL) in capillary electrophoresis (CE) when resolved with native beta-cyclodextrin (beta-CD) and heptakis (2,3-diacetyl-6-sulfo)-beta-CD (HDAS-beta-CD). The possible mechanisms of the affinity reversal of the CL en... |
11589276 | Enantiomeric separation of hydroxy acids and carboxylic acids by diamino-beta-cyclodextrins (AB,AC,AD) in capillary electrophoresis. | Selectively modified 6,6'-dideoxy-6,6'-L-diamino-beta-cyclodextrins (AB, AC, AD) were successfully used as chiral selectors for the enantiomeric separation of hydroxy acids and carboxylic acids (in particular, phenoxyalkanoic acid herbicides) in capillary electrophoresis (CE). Chiral separations were obtained at a low ... |
11589275 | pH-dependence of complexion constants and complex mobility in capillary electrophoresis separations of dipeptide enantiomers. | The chiral separation of the LL- and DD-enantiomers of the dipeptides Ala-Tyr, Phe-Phe, and Asp-PheOMe has been investigated at pH 2.5 and pH 3.5 using beta-cyclodextrin (beta-CD), heptakis-(2,6-di-O-methyl)-beta-cyclodextrin, and heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin as chiral selectors. According to electro... |
11589274 | Heptakis(2-O-methyl-3,6-di-O-sulfo)-beta-cyclodextrin: a single isomer, 14-sulfated beta-cyclodextrin for use as a chiral resolving agent in capillary electrophoresis. | The first single-isomer, 14-sulfated beta-cyclodextrin, the sodium salt of heptakis(2-O-methyl-3,6-di-O-sulfo)-beta-cyclodextrin (HMdiSu) has been used to separate 24 pharmaceutical weak base enantiomers in pH 2.5 background electrolytes using capillary electrophoresis. For the weakly binding bases, the cationic effect... |
11589273 | Enantioseparations by capillary electrochromatography. | The review summarizes recent developments in enantioseparations by capillary electrochromatography (CEC). Selected fundamental aspects of CEC are discussed in order to stress those features which may allow the success of this technique in the competitive field of enantioseparations. In addition, the comparative charact... |
11589272 | Recent developments in chiral capillary electrophoresis and applications of this technique to pharmaceutical and biomedical analysis. | This paper provides an overview of the current status of chiral capillary electrophoresis (CE). The emphasis is placed on the application of CE in chiral separation of various racemic compounds. During the last two years about 280 papers, several review articles, and two entire issues, edited by S. Fanali (Electrophore... |
11587341 | Rapid chiral on-chip separation with simplified amperometric detection. | The enantiomers of adrenaline, noradrenaline, ephedrine and pseudoephedrine were separated by capillary electrophoresis on a micromachined device. Detection was carried out with a new two-electrode amperometric detector, eliminating the need for individual counter and reference electrodes. Separation of the isomers was... |
11585132 | Chiral analysis of methylphenidate and dextromoramide by capillary electrophoresis. | Capillary electrophoretic methods have been developed to separate the enantiomers of methylphenidate (MPH) and dextromoramide. For MPH separation was achieved with heptakis (2,6-di-O-methyl)-beta-cyclodextrin (DMCD) as chiral selector in a 100 mM phosphoric acid buffer adjusted to pH 3.0 with triethanolamine. Commercia... |
11576330 | The nature of the bond between peptide and carrier molecule determines the immunogenicity of the construct. | The influence of the nature of the bond between a peptide and a (lipidic) carrier molecule on the immunogenicity of that construct was investigated. As types of bonds a thioester-, a disulfide-, an amide- and a thioether bond were investigated. As carrier molecules a peptide, an N-palmitoylated peptide or a C(16)-hydro... |
11576530 | Slotoxin, alphaKTx1.11, a new scorpion peptide blocker of MaxiK channels that differentiates between alpha and alpha+beta (beta1 or beta4) complexes. | A novel peptide from Centruroides noxius Hoffmann scorpion venom was isolated and sequenced. The 37 amino acid peptide belongs to the charybdotoxin sub-family (alphaKTx1) and was numbered member 11. alphaKTx1.11 has 75% sequence identity with iberiotoxin and 54% with charybdotoxin. alphaKTx1.11 revealed specificity for... |
11575781 | Organometallic supramolecular chemistry with monosaccharides: triethylammonium mu-chloro-bis[chloro(eta5-cyclopentadienyl)-(methyl 4,6-o-benzylidene-beta-D-glucopyranosidato-1kappaO2,1:2kappaO3) zirconate]. | The reaction of [CpZrCl3(thf)2] with methyl 4,6-O-benzylidene-beta-D-glucopyranoside (beta-MeBGH2, 1) in the presence of Et3N results in the formation of the zirconate complex [Et3NH] [(CpZrCl)2(mu-Cl) (mu-(beta-MeBG)]2] (2). X-ray structure analyses were performed from the ligand precursor beta-MeBGH2 1 as well as fro... |
11575780 | Crown compounds for anions: sandwich and half-sandwich complexes of cyclic trimetric perfluoro-o-phenylenemercury with polyhedral closo-[B10H10]2- and closo-[B12H12]2- anions. | It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4-Hg)3 (1) is capable of binding closo-[B10H10]2- and closo-[B12H12]2- anions to form complexes [[(o-C6F4Hg)3](B10-H10)]2- (2), [[(o-C6F4Hg)3]2(B10H10)]2-(3), [[(o-C6F4Hg)3](B12H12)]2- (4), and [[(o-C6F4Hg)3]2(B12H12)]2... |
11575772 | Cationic host-guest polymerization of N-vinylcarbazole and vinyl ethers in MCM-41, MCM-48, and nanoporous glasses. | The synthesis of poly(vinyl ether)s or polyvinylcarbazole under the conditions of constricted geometry can be achieved by means of cationic host-guest polymerisation of the corresponding monomers in the pores of MCM-41 (pore diameter 3.6 nm), MCM-48 (pore diameter 2.4 nm) and in nanoporous glasses (Gelsil with a pore d... |
11575764 | Classification of coordination polygons and polyhedra according to their mode of self-assembly. | This work extends techniques for the controlled formation of synthetic molecular containers by metal-mediated self-assembly. A new classification system based on the self-assembly of such species is proposed. The system: 1) allows a systematic identification of suitable acceptor-donor combinations, 2) widens the variet... |
11573004 | Posttranscriptional regulation of gene expression in learning by the neuronal ELAV-like mRNA-stabilizing proteins. | The view that memory is encoded by variations in the strength of synapses implies that long-term biochemical changes take place within subcellular microdomains of neurons. These changes are thought ultimately to be an effect of transcriptional regulation of specific genes. Localized changes, however, cannot be fully ex... |
11572984 | Self-organization of a propulsive actin network as an evolutionary process. | The leading edge of motile cells is propelled by polymerization of actin filaments according to a dendritic nucleation/array treadmilling mechanism. However, little attention has been given to the origin and maintenance of the dendritic array. Here we develop and test a population-kinetics model that explains the organ... |
11572979 | Disordered to ordered folding in the regulation of diphtheria toxin repressor activity. | Understanding how metal binding regulates the activity of the diphtheria toxin repressor protein (DtxR) requires information about the structure in solution. We have prepared a DtxR mutant construct with three additional N-terminal residues, Gly-Ser-His-DtxR(Cys-102 --> Asp), that retains metal-binding capabilities, bu... |
11572974 | Design of potent inhibitors of HIV-1 entry from the gp41 N-peptide region. | The HIV-1 gp41 envelope glycoprotein promotes fusion of the virus and cell membranes through the formation of a trimer-of-hairpins structure, in which the amino- and carboxyl-terminal regions of the gp41 ectodomain are brought together. Synthetic peptides derived from these two regions (called N and C peptides, respect... |
11572967 | Glutamatergic modulation of hyperactivity in mice lacking the dopamine transporter. | In the brain, dopamine exerts an important modulatory influence over behaviors such as emotion, cognition, and affect as well as mechanisms of reward and the control of locomotion. The dopamine transporter (DAT), which reuptakes the released neurotransmitter into presynaptic terminals, is a major determinant of the int... |
11571564 | Development of formulations that enhance physical stability of viral vectors for gene therapy. | This study summarizes our initial efforts to address an issue that is critical to the success of any multicenter gene therapy clinical trial - maintenance of vector viability during shipping and storage at remote test sites. We have identified formulation and processing factors that influence stability of viral prepara... |
11566273 | Progressive accretion of amelogenin molecules during nanospheres assembly revealed by atomic force microscopy. | Amelogenin proteins, the principal components of the developing dental enamel matrix, self-assemble to form nanosphere structures that are believed to function as structural components directly involved in the matrix mediated enamel biomineralization. The self-assembly behavior of a recombinant murine amelogenin (rM179... |
11566263 | Amelogenins: assembly, processing and control of crystal morphology. | The remarkable properties of enamel crystals and their arrangements in an extraordinary micro-architecture are clear indications that the processes of crystal nucleation and growth in the extracellular matrix are highly controlled. The major extracellular events involved in enamel formation are: (a) delineation of spac... |
11566327 | Platinum(II) complexes with 2-acetyl pyridine thiosemicarbazone. Synthesis, crystal structure, spectral properties, antimicrobial and antitumour activity. | An interesting series of new platinum complexes has been synthesized by the reaction of Na(2)PtCl(4) with 2-acetyl pyridine thiosemicarbazone, HAcTsc. The new complexes, [Pt(AcTsc)Cl], [Pt(HAcTsc)(2)]Cl(2) and [Pt(AcTsc)(2)], have been characterized by elemental analyses and spectroscopic studies. The crystal structure... |
11566886 | Specificity of the HP1 chromo domain for the methylated N-terminus of histone H3. | Recent studies show that heterochromatin-associated protein-1 (HP1) recognizes a 'histone code' involving methylated Lys9 (methyl-K9) in histone H3. Using in situ immunofluorescence, we demonstrate that methyl-K9 H3 and HP1 co-localize to the heterochromatic regions of Drosophila polytene chromosomes. NMR spectra show ... |
11564990 | Angiotensin II-induced apoptosis in rat cardiomyocyte culture: a possible role of AT1 and AT2 receptors. | <h4>Objectives</h4>To investigate the mechanism of angiotensin II-induced apoptosis in cultured cardiomyocytes by determining which receptor subtype is involved, and what is the relationship between intracellular Ca2+ changes and apoptosis.<h4>Design and methods</h4>Neonatal rat cardiomyocytes were pretreated with eith... |
11564756 | E-cadherin regulates cell growth by modulating proliferation-dependent beta-catenin transcriptional activity. | beta-Catenin is essential for E-cadherin-mediated cell adhesion in epithelial cells, but it also forms nuclear complexes with high mobility group transcription factors. Using a mouse mammary epithelial cell system, we have shown previously that conversion of epithelial cells to a fibroblastoid phenotype (epithelial-mes... |
11562218 | Novel [2]catenane structures introducing communication between transition metal centers via pi...pi interactions. | [2]Catenane systems containing copper(II) and nickel(II) as metal centers have been self-assembled using tetraazamacrocyclic complexes and benzo-24-crown-8 as building blocks. A variety of methods, including X-ray crystallography, ESI mass spectrometry, (13)C and (1)H NMR, and electrochemistry, were applied to characte... |
11562215 | Approaches to the synthesis of (+/-)-strychnine via the cobalt-mediated [2 + 2 + 2] cycloaddition: rapid assembly of a classic framework. | Five synthetic approaches to racemic strychnine (1), with the cobalt-mediated [2 + 2 + 2] cycloaddition of alkynes to indoles as the key step, are described. These include the generation and attempted cyclization of macrocycle 8 and the synthesis of dihydrocarbazoles 15, 22, and 26 and their elaboration to pentacyclic ... |
11562207 | The magnitude of [C-H...O] hydrogen bonding in molecular and supramolecular assemblies. | Ab initio calculations at the MP2/6-311++G** level on model systems (N-methylpyridinium complexes of dimethyl ether and dimethyl phosphate anion) provide quantitative measures of the large stabilization energies that arise from [C-H...O] contacts in charged systems. These attractive interactions control (i) the self-as... |
11559197 | Synthesis, aggregation, and chiroptical properties of chiral, amphiphilic dendrimers. | The syntheses of amphiphilic dendrimers based on 3,5-dihydroxybenzyl alcohol containing tri- or tetrafunctional chiral central cores and allyl ester termini are described. Water solubility is imparted to the dendrimers via a palladium-catalyzed deprotection of the peripheral allyl esters. This method affords complete d... |
11559075 | The self-assembly of a [Ga4L6](12-) tetrahedral cluster thermodynamically driven by host-guest interactions. | The guest-induced synthesis of a [Ga4L6](12-) tetrahedral metal-ligand cluster resulting from a predictive design strategy is described. Each of the six dicatecholamide ligands spans an edge of the molecular tetrahedron with four Ga(III) ions at the vertices. Small cationic species not only were found to occupy the lar... |
11559360 | Solution structure of the lipoyl domain of the chimeric dihydrolipoyl dehydrogenase P64K from Neisseria meningitidis. | The antigenic P64K protein from the pathogenic bacterium Neisseria meningitidis is found in the outer membrane of the cell, and consists of two parts: an 81-residue N-terminal region and a 482-residue C-terminal region. The amino-acid sequence of the N-terminal region is homologous with the lipoyl domains of the dihydr... |
11558604 | A novel 1:1 complex of potassium mikanin-3-O-sulfate with methanol. | Mikanin-3-O-sulfate (1), in the form of its potassium salt, together with mikanin (2) and alpinetin (3) were isolated from Mikania micrantha. The crystal structures of K(1) x CH3OH, 2 and 3 x H2O were established by X-ray crystallography. The potassium ions in K(1) x CHO3H are bridged by O5, O7 and O8 to form a chain o... |
11557821 | Peptide-mediated RNA delivery: a novel approach for enhanced transfection of primary and post-mitotic cells. | Synthetic vectors were evaluated for their ability to mediate efficient mRNA transfection. Initial results indicated that lipoplexes, but not polyplexes based on polyethylenimine (PEI, 25 and 22 kDa), poly(L-lysine) (PLL, 54 kDa) or dendrimers, mediated efficient translation of mRNA in B16-F10 cells. Significant mRNA t... |
11557806 | Nucleoside triphosphate-dependent restriction enzymes. | The known nucleoside triphosphate-dependent restriction enzymes are hetero-oligomeric proteins that behave as molecular machines in response to their target sequences. They translocate DNA in a process dependent on the hydrolysis of a nucleoside triphosphate. For the ATP-dependent type I and type III restriction and mo... |
11555300 | New erythromycin derivatives from Saccharopolyspora erythraea using sugar O-methyltransferases from the spinosyn biosynthetic gene cluster. | Using a previously developed expression system based on the erythromycin-producing strain of Saccharopolyspora erythraea, O-methyltransferases from the spinosyn biosynthetic gene cluster of Saccharopolyspora spinosa have been shown to modify a rhamnosyl sugar attached to a 14-membered polyketide macrolactone. The spnI,... |
11553808 | Structural features of an influenza virus promoter and their implications for viral RNA synthesis. | The influenza A virus, a severe pandemic pathogen, has a segmented RNA genome consisting of eight single-stranded RNA molecules. The 5' and 3' ends of each RNA segment recognized by the influenza A virus RNA-dependent RNA polymerase direct both transcription and replication of the virus's RNA genome. Promoter binding b... |
11553726 | Mammalian dynamin-like protein DLP1 tubulates membranes. | Dynamins are large GTPases with mechanochemical properties that are known to constrict and tubulate membranes. A recently identified mammalian dynamin-like protein (DLP1) is essential for the proper cellular distribution of mitochondria and the endoplasmic reticulum in cultured cells. In this study, we investigated the... |
11553714 | The GTPase effector domain sequence of the Dnm1p GTPase regulates self-assembly and controls a rate-limiting step in mitochondrial fission. | Dnm1p belongs to a family of dynamin-related GTPases required to remodel different cellular membranes. In budding yeast, Dnm1p-containing complexes assemble on the cytoplasmic surface of the outer mitochondrial membrane at sites where mitochondrial tubules divide. Our previous genetic studies suggested that Dnm1p's GTP... |
11553700 | Dynamin GTPase domain mutants block endocytic vesicle formation at morphologically distinct stages. | Abundant evidence has shown that the GTPase dynamin is required for receptor-mediated endocytosis, but its exact role in endocytic clathrin-coated vesicle formation remains to be established. Whereas dynamin GTPase domain mutants that are defective in GTP binding and hydrolysis are potent dominant-negative inhibitors o... |
11553673 | Cholesterol depletion by methyl-beta-cyclodextrin blocks cholera toxin transport from endosomes to the Golgi apparatus in hippocampal neurons. | We recently demonstrated that although cholera toxin (CT) is found in detergent-insoluble domains/rafts at the cell surface of cultured hippocampal neurons, it is internalized via a raft-independent mechanism. Thus, cholesterol depletion by methyl-beta-cyclodextrin (MbetaCD) did not affect the rate of CT internalizatio... |
11552799 | Design, formation and properties of tetrahedral M(4)L(4) and M(4)L(6) supramolecular clusters. | The rigid tris- and bis(catecholamide) ligands H(6)A, H(4)B and H(4)C form tetrahedral clusters of the type M(4)L(4) and M(4)L(6) through self-assembly reactions with tri- and tetravalent metal ions such as Ga(III), Fe(III), Ti(IV) and Sn(IV). General design principles for the synthesis of such clusters are presented w... |
11552798 | Orthogonal, convergent syntheses of dendrimers based on melamine with one or two unique surface sites for manipulation. | An orthogonal, convergent route for the introduction of substoichiometric numbers of latent surface sites into dendrimers based on melamine is used to prepare targets that display one or two Boc-protected amines on the periphery. Asymmetry is the result of the stepwise incorporation of functionalized and unfunctionaliz... |
11553488 | Artificial receptors involved in enolization and pK(a) shifts. | Abiotic receptors used to enolize carbonyl compounds or to shift substrate pK(a) values are reviewed. These systems exhibit disparate frameworks and several approaches to binding and anion stabilization. Detailed emphasis is placed on a bicyclic cyclophane that induces pK(a) shifts in active methylene compounds through... |
11553487 | Specific host-guest interactions in a protein-based artificial transaminase. | Artificial enzymes can be created by covalent attachment of a catalytic active group to a protein scaffold. Recently, we assembled an artificial transaminase by conjugation of intestinal fatty acid binding protein (IFABP) with a pyridoxamine derivative via a disulfide bond; the resulting construct catalyzed a transamin... |
11553476 | Functionalized oligoanthranilamides: modular and conformationally controlled scaffolds. | This paper describes the use of functionalized oligoanthranilamides as conformationally controlled scaffolds for molecular recognition. Oligomers of anthranilamides are stabilized by the formation of intramolecular six-membered hydrogen bonds in a linear strand conformation. Onto alternate anthranilic acid units, we ha... |
11550252 | 3D MR angiography of intratumoral vasculature using a novel macromolecular MR contrast agent. | Noninvasive methods to visualize blood flow in the intratumoral vasculature have not previously been studied. In the present study, the use of a novel intravascular MR contrast agent with a generation-6 polyamidoamine dendrimer core (G6-(1B4M-Gd)192; MW: 175kD) was investigated, and the vasculature in experimental tumo... |
11550236 | Novel intravascular macromolecular MRI contrast agent with generation-4 polyamidoamine dendrimer core: accelerated renal excretion with coinjection of lysine. | One of the major limitations to macromolecular MRI contrast agents (MRI-CAs) is their slow clearance and associated decreased excretion of gadolinium (Gd(III)). The effect of coinjecting lysine to accelerate renal excretion of a macromolecular MRI-CA (generation-4 PAMAM dendrimer (G4D-(1B4M-Gd)64)) was investigated. Th... |
11549753 | Correlation of AMPA receptor subunit composition with synaptic input in the mammalian cochlear nuclei. | The composition of AMPA receptors in patches excised from somata and dendrites of six cell types in the mammalian cochlear nuclei was probed and compared electrophysiologically and pharmacologically with the rapid application of glutamate. Cells excited predominantly by auditory nerve fibers had AMPA receptors with exc... |
11549360 | Analysis of combinatorial chemistry samples by micellar electrokinetic chromatography. | A micellar electrokinetic chromatography (MEKC) method has been developed that can evaluate the purity of samples generated in combinatorial chemistry libraries. This method uses an open tube capillary (27 cm x 50 microm) along with a run buffer composed of sodium dodecyl sulfate (SDS), hydroxypropyl-beta-cyclodextrin,... |
11549256 | Differential effects of filipin and methyl-beta-cyclodextrin on B cell receptor signaling. | Methyl-beta-cyclodextrin and filipin are cholesterol-binding reagents often used interchangeably to investigate functional requirements for lipid rafts in receptor-mediated signal transduction. Recently, contradictory results were reported by two groups using these reagents in different model systems to investigate the... |
11549244 | Biliary anionic peptide fraction/calcium binding protein inhibits apolipoprotein A-I-mediated cholesterol efflux from cultured cells. | The ABC transporter ABCA1 has been implicated to control cholesterol efflux in a variety of cell types including macrophages, fibroblasts, and intestinal epithelial cells. In this study we have investigated whether the 6-kD protein anionic peptide fraction/calcium binding protein (APF/CBP) which has homology to apolipo... |
11549602 | The inner ear of dogs with X-linked nephritis provides clues to the pathogenesis of hearing loss in X-linked Alport syndrome. | Alport syndrome is an inherited disorder of type IV collagen with progressive nephropathy, ocular abnormalities, and high-tone sensorineural deafness. In X-linked Alport syndrome, mutations in the COL4A5 gene encoding the alpha5 chain of type IV collagen lead to loss of the alpha3/alpha4/alpha5 network and increased su... |
11543678 | Acyclic and cyclopropyl analogues of adenosine bisphosphate antagonists of the P2Y1 receptor: structure-activity relationships and receptor docking. | The activation of P2Y1 receptors in platelets contributes to platelet aggregation, and selective antagonists are sought as potential antithrombotic agents. We reported (Kim et al. J. Med. Chem. 2000, 43, 746-755) that acyclic analogues of adenine nucleotides, containing two phosphate groups on a symmetrically branched ... |
11533663 | Rac1 orientates epithelial apical polarity through effects on basolateral laminin assembly. | Cellular polarization involves the generation of asymmetry along an intracellular axis. In a multicellular tissue, the asymmetry of individual cells must conform to the overlying architecture of the tissue. However, the mechanisms that couple cellular polarization to tissue morphogenesis are poorly understood. Here, we... |
11532583 | Quantitative structure-binding relationships (QSBR) and artificial neural networks: improved predictions in drug:cyclodextrin inclusion complexes. | The application of the principal neural network architecture, namely the multilayer perceptron (MLP), have been developed for obtaining sufficient quantitative structure-binding relationships (QSBR) with high accuracy. To this end a dataset of 17 barbiturates as guests complexing to alpha- and beta-cyclodextrins was ex... |
11531447 | Oxonium ions from aqua regia: isolation by hydrogen bonding to crown ethers. | The preparation and structures of a variety of oxonium ion tetrachloroaurate(III) salts isolated from aqua regia are reported. The new compounds are [(H(5)O(2))(2)(12-crown-4)(2)][AuCl(4)](2) (1), [(H(7)O(3))(15-crown-5)][AuCl(4)] (2), [(H(5)O(2))(benzo-15-crown-5)(2)][AuCl(4)] (3), [(H(3)O)(18-crown-6)][AuCl(4)] (4), ... |
11531446 | Verdoheme reactivity. Remarkable paramagnetically shifted (1)H NMR spectra of intermediates from the addition of hydroxide or methoxide with Fe(II) and Fe(III) verdohemes. | Studies of the reaction of 5-oxaporphyrin iron complexes (verdohemes) with methoxide ion or hydroxide ion have been undertaken to understand the initial step of ring opening of verdohemes. High-spin [ClFe(III)(OEOP)] undergoes a complex series of reactions upon treatment with hydroxide ion in chloroform, and similar sp... |
11531434 | Cyano-bridged bimetallic assemblies from hexacyanometalate, [M(CN)6](3-) (M = Mn(III) and Fe(III)), and [M(N4-macrocycle)]2+ (M=Fe(III), Ni(II) and Zn(II)) building blocks. Syntheses, multidimensional structures, and magnetic properties. | Reactions between [M(N(4)-macrocycle)](2+) (M = Zn(II) and Ni(II); macrocycle ligands are either CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane or cyclam = 1,4, 8, 11-tetrazaazaciclotetradecane) and [M(CN)(6)](3-) (M = Fe(III) and Mn(III)) give rise to cyano-bridged assemblies with 1D linear chai... |
11531431 | Alkyl and aryl substituted corroles. 2. Synthesis and characterization of linked "face-to-face" biscorroles. X-ray structure of (BCA)Co(2)(py)(3), where BCA represents a biscorrole with an anthracenyl bridge. | The synthesis, spectroscopic properties, and electrochemistry of (BCA)Co(2) and (BCB)Co(2) are described where BCA and BCB represent biscorroles linked by an anthracenyl (A) or a biphenylenyl (B) bridge. The pyridine and CO binding properties of (BCA)Co(2) and (BCB)Co(2) are also presented, and one of the compounds in ... |
11531430 | Alkyl and aryl substituted corroles. 1. Synthesis and characterization of free base and cobalt containing derivatives. x-ray structure of (Me(4)Ph(5)Cor)Co(py)(2). | The synthesis, spectroscopic properties, and electrochemistry of six different alkyl- and aryl-substituted Co(III) corroles are presented. The investigated compounds contain methyl, ethyl, phenyl, or substituted phenyl groups at the eight beta-positions of the corrole macrocycle and four derivatives also contain a phen... |
11532966 | Glycan-dependent signaling: O-linked N-acetylglucosamine. | The addition of O-linked N-acetylglucosamine (O-GlcNAc) to target proteins may serve as a signaling modification analogous to protein phosphorylation. Like phosphorylation, O-GlcNAc is a dynamic modification occurring in the nucleus and cytoplasm. Various analytical methods have been developed to detect O-GlcNAc and di... |
11532932 | RNA interference of a trypanosome topoisomerase II causes progressive loss of mitochondrial DNA. | We studied the function of a Trypanosoma brucei topoisomerase II using RNA interference (RNAi). Expression of a topoisomerase II double-stranded RNA as a stem-loop caused specific degradation of mRNA followed by loss of protein. After 6 days of RNAi, the parasites' growth rate declined and the cells subsequently died. ... |
11531245 | Pemetrexed disodium in recurrent locally advanced or metastatic squamous cell carcinoma of the head and neck. | This phase II study determined response rate of patients with locally advanced or metastatic head and neck cancer treated with pemetrexed disodium, a new multitargeted antifolate that inhibits thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase. 35 patients with local or meta... |
11531024 | Post-hemorrhagic shock mesenteric lymph lipids prime neutrophils for enhanced cytotoxicity via phospholipase A2. | Hemorrhagic shock induced mesenteric hypoperfusion has long been implicated as a key event in the pathogenesis of the adult respiratory distress syndrome (ARDS) and multiple organ failure (MOF). Previous work links post-hemorrhagic shock mesenteric lymph (PHSML) lipids and neutrophil (PMN) priming in the pathogenesis o... |
11529792 | A synthetic strategy for the cyclodepsipeptide core of the antitumor antibiotic verucopeptin. | [reaction: see text]. An efficient [2 + 2 + 2]-fragment condensation strategy is described for obtaining the cyclodepsipeptide core of verucopeptin. The 19-membered macrocycle was established through a Carpino HATU mediated macrolactamization, which proceeded in good yield under high-dilution conditions. |
11529742 | Optically active BINOL core-based phenyleneethynylene dendrimers for the enantioselective fluorescent recognition of amino alcohols. | A dramatic enhancement in fluorescence intensity from 1,1'-bi-2-naphthol (BINOL) to dendritic phenyleneethynylenes containing the BINOL core was observed. The strong fluorescence of the dendrimers allows a very small amount of the chiral materials to be used for sensing. The light harvesting antennas of the dendrimer f... |
11529729 | Studies on the total synthesis of disorazole C1. An advanced macrocycle intermediate. | Synthesis of protected tetradehydro-(6,6'-S)-(14,14'-S)-(16,16'-R)-disorazole (3), a potential precursor to the natural product disorazole C1 (1), is described. Key features of this work include (a) an unprecedented sequential 1,5 O --> O silyl rearrangement/Horner-Wadsworth-Emmons reaction used to construct 18, (b) a ... |
11529722 | Crystal engineering using anilic acids and dipyridyl compounds through a new supramolecular synthon. | The anilic acids, 2,5-dihydroxy-1,4-benzoquinone (1a), 2,5-dibromo-3,6-dihydroxy-1,4-benzoquinone (bromanilic acid; 1b), 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid; 1c), and 2,5-dicyano-3,6-dihydroxy-1,4-benzoquinone (cyananilic acid; 1d), were cocrystallized with rigid organic ligands containing two... |
11530006 | Structural basis of bacterial photosynthetic reaction centers. | The photosynthetic reaction center (RC) is the first membrane protein whose three-dimensional structure was revealed at the atomic level by X-ray crystallograph more than fifteen years ago. Structural information about RC made a great contribution to the understanding of the reaction mechanism of the complicated membra... |
11528005 | Polar flagellar motility of the Vibrionaceae. | Polar flagella of Vibrio species can rotate at speeds as high as 100,000 rpm and effectively propel the bacteria in liquid as fast as 60 microm/s. The sodium motive force powers rotation of the filament, which acts as a propeller. The filament is complex, composed of multiple subunits, and sheathed by an extension of t... |
11528003 | Allosteric regulation of catalytic activity: Escherichia coli aspartate transcarbamoylase versus yeast chorismate mutase. | Allosteric regulation of key metabolic enzymes is a fascinating field to study the structure-function relationship of induced conformational changes of proteins. In this review we compare the principles of allosteric transitions of the complex classical model aspartate transcarbamoylase (ATCase) from Escherichia coli, ... |
11527532 | Role of Phe286 in the recognition mechanism of cyclomaltooligosaccharides (cyclodextrins) by Thermoactinomyces vulgaris R-47 alpha-amylase 2 (TVAII). X-ray structures of the mutant TVAIIs, F286A and F286Y, and kinetic analyses of the Phe286-replaced mutant TVAIIs. | Phe286 located in the center of the active site of alpha-amylase 2 from Thermoactinomyces vulgaris R-47 (TVAII) plays an important role in the substrate recognition for cyclomaltooligosaccharides (cyclodextrins). The X-ray structures of mutant TVAIIs with the replacement of Phe286 by Ala (F286A) and Tyr (F286Y) were de... |
11527718 | Synthesis and purine receptor affinity of 6-oxopurine nucleosides and nucleotides containing (N)-methanocarba-pseudoribose rings. | 6-Oxopurine derivatives containing a northern (N) methanocarba modification (i.e., fused cyclopropane and cyclopentane rings in place of the ribose) were synthesized and the adenosine receptor affinity measured. Guanine or hypoxanthine was coupled at the 7-position, or 1,3-dibutylxanthine was coupled at the 9-position.... |
11525666 | Paramagnetic cobalt(II) as an NMR probe of dendrimer structure: mobility and cooperativity of dendritic arms. | Cobalt(II) has been utilized as an external paramagnetic (1)H NMR probe for the study of the structure of dendrimers that possess specifically located metal recognition sites. The hyperfine-shifted (1)H NMR signals of the Co(II) complexes of several 2,6-diamidopyridine-containing dendrimers have been fully assigned by ... |
11525659 | Asymmetric total synthesis of ent-(-)-roseophilin: assignment of absolute configuration. | An asymmetric total synthesis of ent-(-)-roseophilin (1), the unnatural enantiomer of a novel naturally occurring antitumor antibiotic, is described. The approach enlists a room temperature heterocyclic azadiene inverse electron demand Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate (7) with the op... |
11525651 | Noncovalently functionalized dendrimers as recyclable catalysts. | The efficient reversible functionalization of the periphery of urea adamantyl poly(propylene imine) dendrimers with catalytic sites using noncovalent interactions is described. Phosphine ligands equipped with urea acetic groups, a binding motive complementary to that of the dendrimer host, have been prepared and assemb... |
11525988 | Antimicrobial properties of pyridine-2,6-dithiocarboxylic acid, a metal chelator produced by Pseudomonas spp. | Pyridine-2,6-dithiocarboxylic acid (pdtc) is a metal chelator produced by Pseudomonas spp. It has been shown to be involved in the biodegradation of carbon tetrachloride; however, little is known about its biological function. In this study, we examined the antimicrobial properties of pdtc and the mechanism of its anti... |
11523992 | Membrane cholesterol modulates serotonin transporter activity. | The synaptic actions of the neurotransmitter serotonin are terminated by a selective high-affinity reuptake mediated by the serotonin transporter (SERT). To gain insight into the modulation of the functional properties of this integral membrane protein by cholesterol, a main component of the lipid bilayer, we stably ex... |
11522837 | Mechanism of mammalian mitochondrial DNA replication: import of mitochondrial transcription factor A into isolated mitochondria stimulates 7S DNA synthesis. | The light strand promoter of mammalian mitochondrial DNA gives rise to a primary transcript, but also to the RNA primer necessary for initiation of replication and 7S DNA synthesis as well as 7S RNA. Here we have studied the turnover of 7S DNA in isolated rat liver mitochondria and whether import of mitochondrial trans... |
11522437 | Presence of neuronal nitric oxide synthase in autonomic and sensory ganglion neurons innervating the lacrimal glands of the cat: an immunofluorescent and retrograde tracer double-labeling study. | It is generally considered that parasympathetic postganglionic nerve fibers innervating the lacrimal gland (LG) arise from the pterygopalatine ganglion (PPG), while sympathetic and sensory innervations arise from the superior cervical ganglion (SCG) and trigeminal ganglion (TG), respectively. Recently, we reported for ... |
11522475 | Combined effect of oleic acid and propylene glycol on the percutaneous penetration of tenoxicam and its retention in the skin. | The influence of oleic acid (OA) on the in vitro percutaneous absorption of tenoxicam (TEN) and its combined effect with propylene glycol (PG) was studied using Franz-type diffusion cells. Furthermore, at defined concentrations of OA, complexes of the drug with cyclodextrins (MbetaCD and gammaCD) were added because the... |
11520799 | Role for lipid rafts in regulating interleukin-2 receptor signaling. | Lipid rafts are plasma membrane microdomains characterized by a unique lipid environment enriched in gangliosides and cholesterol, leading to their insolubility in nonionic detergents. Many receptors are constitutively or inducibly localized in lipid rafts, which have been shown to function as platforms coordinating th... |
11516170 | Characterization of parazoanthoxanthin A binding to a series of natural and synthetic host DNA duplexes. | Parazoanthoxanthin A is a fluorescent yellow nitrogenous pigment of the group of zoanthoxanthins, which show a broad range of biological activity. These include, among others, the ability to bind to DNA. In this study we have used a variety of spectroscopic (intrinsic fluorescence emission and UV-spectroscopy) and hydr... |
11516788 | Intranasal vaccination against plague, tetanus and diphtheria. | Plague is an extremely virulent and potentially lethal infection caused by the bacterium Y. pestis. The current vaccine used to immunise against plague often fails to engender solid (100%) protection against inhalational infection with Y. pestis. Similarly, logistical factors favour the development of non-parenteral im... |
11514679 | Chemical denaturation and elevated folding temperatures are required for wild-type activity and stability of recombinant Methanococcus jannaschii 20S proteasome. | The 20S proteasome from the extreme thermophile Methanococcus jannaschii (Mj) was purified and sequenced to facilitate production of the recombinant proteasome in E. coli. The recombinant proteasome remained in solution at a purity level of 80-85% (according to SDS PAGE) following incubation of cell lysates at 70 degre... |
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