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7017282 | Regulation of high-affinity leucine transport in Escherichia coli. | Leucine is transported into E coli by two osmotic shock-sensitive, high-affinity systems (LIV-I and leucine-specific systems) and one membrane bound, low-affinity system (LIV-II). Expression of the high-affinity transport systems is altered by mutations in livR and 1stR, genes for negatively acting regulatory elements,... |
6264235 | Properties of receptors for epidermal growth factor in detergent solution: evidence for heterogeneous aggregated states. | Between 60% and 100% of epidermal growth factor (EGF) binding activity was recovered from membranes of the A431 human epidermoid carcinoma cell line treated with solutions containing the nonionic detergent Triton X-100. Approximately half of the recovered binding activity was sedimented at low centrifugal force and hen... |
7017281 | Alterations in the responsiveness of diabetic fibroblasts to insulin. | Fibroblastic cultures from the skin of nondiabetic and diabetic (db/db) mice have been used to investigate alterations in the biological responses of diabetic cells to insulin. Confluent cultures from the skin of both nondiabetic and diabetic animals possess specific receptors for insulin. Diabetic fibroblasts exhibit ... |
6454029 | Control of mouse myoblast commitment to terminal differentiation by mitogens. | Regulation of the transition of mouse myoblasts from proliferation to terminal differentiation was studied with clonal density cultures of a permanent clonal myoblast cell line. In medium lacking mitogenic activity, mouse myoblasts withdraw from the cell cycle, elaborate muscle-specific gene products, and fuse to form ... |
6264234 | Selective protein transport: identity of the solubilized phosvitin receptor from chicken oocytes. | By two independent methods, the solubilized receptor for phosvitin (PV) has a subunit MW of 116K. Affinity chromatography, showed that only 2 of the more than 25 proteins present in the total detergent solubilized oocyte membrane extract were retained on a PV-agarose column. These proteins of MW of 116K and 100K could ... |
6264233 | Controlled proteolysis of EGF receptors: evidence for transmembrane distribution of the EGF binding and phosphate acceptor sites. | A small quantity of the 125I-EGF (epidermal growth factor) bound specifically to EGF receptors on the human epidermoid carcinoma cell line A431 associates covalently. The direct linkage complex formed migrates during gel electrophoresis as a single diffuse band of MW = 160,000-170,000. In contrast, direct linkage compl... |
6264232 | Direct linkage of EGF to its receptor: characterization and biological relevance. | A small portion of the 125I-EGF that binds specifically to intact cells or isolated membrane from a variety of sources becomes directly and irreversibly linked to EGF receptors. This provides a simple technique for affinity labeling the EGF receptor. Membranes isolated from the human epidermoid carcinoma cell line A431... |
6165866 | Averages of glutamine synthetase molecules as obtained with various skin and electron dose conditions. | Averaged projections of individual glutamine synthetase molecules have been obtained by using electron microscopy and image processing. The methodology of correlation averaging under low dose conditions is described in detail. Because of their low signal-to-noise ratio, images made under low dose conditions cannot be d... |
6972471 | Interleukin 2 in cell-mediated immune responses. | The lymphokine Interleukin 2(IL2) restores T cell responses in a number of in vitro systems where immunogenicity has been compromised. UV irradiation of the stimulating allogeneic cells in a mixed leukocyte culture eliminates the production of cytotoxic T lymphocytes and greatly reduces the DNA synthesis response. IL2 ... |
6941050 | Expression of red cell membrane proteins in erythroid precursor cells. | Specific antibodies to human glycophorin A and spectrin were used to study the expression of these membrane proteins in normal and pathologic human bone marrow. In immunofluorescence experiments spectrin and glycophorin A are found in 50-60% of the nucleated cells in normal bone marrow. These two proteins are expressed... |
7242089 | The effects of laminin on the growth and differentiation of embryonal carcinoma cells in defined media. | In this paper we have examined the growth and differentiation of the embryonal carcinoma cell line, F9, in the defined medium EM-3 at low density. We show that the growth of F9 and their differentiated cells (F9-diff) in EM-3 is strongly density dependent. At low cell densities the growth of both cell types is severely... |
6972470 | Human T-cell growth factor: parameters for production. | Using conditioned media (CM) from phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes (PBL) we observed long-term selective growth of T-cells from normal human donors. This T-cell growth was continuously dependent on addition of a factor called T-cell growth factor (TCGF). The optimal method for preparing ... |
7017279 | Chicken tissue binding sites for a purified chicken lectin. | A lactose-binding lectin previously purified from embryonic chicken muscle and adult chicken liver, and here referred to as chicken-lactose-lectin-I (CLL-I), was added to sections of various adult chicken tissues to detect available binding sites. Both the sites of binding of added CLL-I as well as the tissue distribut... |
6264231 | Cell-cell contact and growth regulation of pinocytosis in 3T3 cells. | In sub-confluent cultures of Balb/c-3T3 cells, pinocytosis rates were increased after exposure to specific growth factors (serum; platelet-derived growth factor, PDGF; epidermal growth factor, EGF). Conversely, as cells became growth-inhibited with increasing culture density, there was a corresponding decline in pinocy... |
6972469 | Erythropoietic enhancing activity (EEA) secreted by the human cell line, GCT. | Medium conditioned by the monocyte-like cell line GCT contains colony-stimulating activity (CSA), a mediator of in vitro granulopoiesis. Also, the conditioned medium (CM) contains erythroid-enhancing activity (EEA), which can be demonstrated in a system utilizing either nonadherent marrow or blood mononuclear cells, er... |
7017278 | Control of animal cell proliferation. | Present understanding of the control of animal cell proliferation is summarized briefly. Major gaps in present knowledge are listed. Models of growth control are discussed. |
6787346 | Reconstitution of binding protein dependent ribose transport in spheroplasts derived from a binding protein negative Escherichia coli K12 mutant and from Salmonella typhimurium. | Highly purified ribose-binding protein from Escherichia coli has been used to reconstitute binding-protein-dependent ribose transport in spheroplasts derived from a binding-protein-deficient mutant of E coli K12, and in spheroplasts derived from Salmonella typhimurium. The cross-species reconstitution was nearly as eff... |
6264230 | Release of adenosine by C1300 neuroblastoma cells in tissue culture. | Previous work in our laboratory led us to postulate that N2a cells release adenosine into growth medium, where it acts at the extracellular adenosine receptors to modulate the sensitivity of the cells to the cyclic AMP-elevating effect of adenosine [Green, RD, J Pharmacol Exp Ther 201:610, 1977]. We have now devised a ... |
6264229 | 5'-p-fluorosulfonylbenzoyladenosine as an ATP site affinity probe for Na+, K+-ATPase. | We have investigated the suitability of 5'-p-fluorosulfonylbenzoyladenosine (FSBA) as an ATP site affinity probe for the canine kidney Na+, K+-ATPase. The purified enzyme is slowly inactivated by this compound in suitable buffers, losing about half of its activity over a two-hour period. The rate of inactivation is mor... |
7017277 | Genetic studies on mechanisms of protein localization in Escherichia coli K-12. | In the last few years, several laboratories have demonstrated that many proteins (both from eukaryotic and prokaryotic organisms) that are destined to be localized in noncytoplasmic locations initially are synthesized as a precursor with a 15-30 amino acid extension at the NH2-terminal end of the molecule. This extra p... |
7017276 | A proton nuclear magnetic resonance investigation of histidine-binding protein J of Salmonella typhimurium: a model for transport of L-histidine across cytoplasmic membrane. | Genetic evidence suggests that the high-affinity L-histidine transport in Salmonella typhimurium requires the participation of a periplasmic binding protein (histidine-binding protein J) and two other proteins (P and Q proteins). The histidine-binding protein J binds L-histidine as the first step in the high-affinity a... |
6164877 | Inhibition of adipose conversion in 3T3-L2 cells by retinoic acid. | The role of retinoic acid in modulating the differentiation of 3T3-L2 fibroblasts into adipocytes has been examined. Results indicate that the retinoid is capable of effectively inhibiting the degree of adipose conversion which is brought about by treatment of preadipocytes with 1-methyl-3-isobutylxanthine plus dexamet... |
6262578 | Specific protein phosphorylation during cyclic AMP-mediated morphological reversion of transformed cells. | Treatment of transformed Chinese hamster ovary cells with dibutyryl cAMP or other agents that elevate cAMP results in the acquisition of growth and morphology characteristic of normal fibroblasts. The role of specific protein phosphorylation in this process of morphological reversion has been examine using metabolic la... |
7230806 | Plate-induced tumors of BALB/3T3 cells exhibiting foci of differentiation into pericytes, chondrocytes, and fibroblasts. | The BALB/3T3 clone A31 mouse embryo cell line has been used by many investigators as a model "normal" "fibroblast" line for a variety in vitro studies. It has been shown, however, that these cells are not "normal" because they will produce tumors within 2-4 months if 3 x 10(4) cells are implanted subcutaneously in BALB... |
6262577 | Restricted infectivity of ecotropic type C retroviruses in mouse teratocarcinoma cells: studies on viral DNA intermediates. | Replication of Gross strain N-tropic type C retrovirus was markedly restricted in a pluripotential undifferentiated embryonal cell line (PCC4) of murine teratocarcinoma, whereas the same virus could cause productive infection in a myoblast-derived differentiated line (PCD1) of the same tumor origin. To investigate the ... |
6971963 | An in vitro assay for T lymphocyte progenitors (CFU-pre T). | Thy-1.2 negative progenitors give rise to Thy-1.2 positive colony cells when mouse bone marrow is cultured in vitro. The bone marrow cells are immobilized in a viscous medium containing methyl cellulose; discrete colonies are identifiable at 2 days and contain 30-60 cells by day 3 of culture. Colonies are tightly packe... |
6262576 | Modulation of EGF binding and action by succinylated concanavalin A in fibroblast cell cultures. | The role of the binding of succinylated concanavalin A to tissue culture cells in influencing epidermal growth factor (EGF)-mediated cell proliferation has been studied. Succinylated concanavalin A dramatically reduces the stimulation of 3T6 cells by EGF in Dulbecco's modified Eagle's medium (DME) containing insulin an... |
6164876 | Regulation of B lymphocyte activation by the Fc portion of immunoglobulin. | Murine splenic B lymphocytes are induced to proliferate and undergo polyclonal activation in the presence of Fc fragments, AHGG, antigen-antibody complexes, and CH3 fragments derived from plasmin digestion of human Ig. The unifying feature of the polyclonal antibody response induced by these agents is that in all cases... |
7230805 | Polypeptide growth factors: some structural and mechanistic considerations. | Polypeptide growth factors ae substances that stimulate an increase in cell size and/or cell number during embryonic development. In some cases, they have a similar effect on tissues in the mature organism where they function as "maintenance" factors to sustain cell viability. While their profound impact on cell behavi... |
6453257 | Polyclonal activation of Ts cells with antiserum directed against an IGH-1 linked candidate for a T-cell receptor constant region marker. | An anti-T cell serum raised in allotype congenic mice recognizes the product of a new locus coding for a heavy chain-linked polypeptide found on a subpopulation of T cells. Anti-Tsd raised in BALB/cAnN mice against selected C.AL-20 T cells reacts with a cell surface antigen in virgin animals that is found on 25% of mat... |
6262575 | Reversible phosphorylation of the membrane-bound acetylcholine receptor. | We have found that the acetylcholine receptor (AChR) of Torpedo californica is phosphorylated and dephosphorylated in situ by a membrane-bound protein kinase and phosphatase [1]. There is increasing evidence that other neurotransmitters [2], light [3-6], polypeptide hormones [7], and growth factors [8-12] also may act ... |
7230804 | Regulation of muscarinic receptor binding by guanine nucleotides and N-ethylmaleimide. | The regulation of muscarinic receptor binding by guanine nucleotides and N-ethylmaleimide (NEM) was investigated using the agonist ligand, [3H] cis methyldioxolane ([3H]CD). Characterization studies on rat forebrain homogenates show that [3H]CD binding was linear with tissue concentration and was unaffected by a change... |
6262574 | Studies on the biogenesis of an enzymatically active complex III of the respiratory chain from yeast mitochondria. | Complex III isolated from yeast mitochondria catalyzed an antimycin A and Diuron-sensitive coenzyme QH2-cytochrome c reductase activity with a turnover number of 15.7 sec(-1) and contained 10 nmoles of cytochrome b and 4.6 nmoles of cytochrome c1 per mg of protein. Electrophoresis in sodium dodecyl sulfate acrylamide g... |
6262573 | Oxytocin action: lack of correlation between receptor number and tissue responsiveness. | Brattleboro rats exhibit diabetes insipidus (DI) because of a genetic autosomal recessive defect in the synthesis of vasopressin; oxytocin is synthesized normally. Preliminary work suggests that elevated circulating oxytocin levels may compensate for the absence of vasopressin. To evaluate the consequences of presumed ... |
6112289 | Induction and long-term maintenance of Thy-1 positive T lymphocytes: derivation from continuous bone marrow cultures. | In the present study we investigated the presence of T-lymphocyte progenitors in the long-term murine bone marrow culture system described by Dexter: mature Thy-1 antigen-bearing T lymphocytes are lost in these cultures after a few days. By culturing nonadherent cells from such cultures in the presence of a supernatant... |
6971962 | Long-term maintenance of "cloned" human PLT cells in TCGF with LCL cells as a feeder layer. | The long-term maintenance of T cells "cloned" by limiting dilution in TCGF was enhanced by the use of irradiated autologous lymphoblastoid cell line (LCL) cells as well as irradiated LCL cells of the individual to which the T cells were originally primed. It was possible to obtain more than 1 X 10(12) cells from a "clo... |
7230803 | The role of cells and their products in the regulation of in vitro stem cell proliferation and granulocyte development. | In long-term marrow cultures haemopoiesis can be maintained in vitro for up to 6 months. Critical analysis of the cell populations produced has shown that the stem cells and their committed progeny have characteristics in common with the corresponding cell types in vivo. The maintenance of haemopoiesis in vitro is asso... |
7230802 | Self-renewal of factor-dependent hemopoietic progenitor cell-lines derived from long-term bone marrow cultures demonstrates significant mouse strain genotypic variation. | Long-term bone marrow cultures established from C57Ks/J mice have been shown to spontaneously release endogenous ecotropic RNA type-C virus (retrovirus). C57Ks/J marrow cultures produced granulocyte-macrophage progenitor cells (GM-CFUc) and immature and mature granulocytes for over 45 weeks. In contrast, NIH Swiss mous... |
6453256 | Regulation of the Balb/c-3T3 cell cycle-effects of growth factors. | The platelet-derived growth factor (PDGF), which is found in serum but not in plasma, has been purified to homogeneity; it stimulates replication at a concentration of 10(-10) M. Brief treatment with PDGF causes density-inhibited Balb/c-3T3 cells to become competent to synthesize DNA; pituitary fibroblast growth factor... |
6971961 | Activation of T lymphocytes by the Fc portion of immunoglobulin. | T lymphocytes are stimulated to release T-cell-replacing factors in response to Fc fragments of human IgG, Lyt 1+23- T cells are directly triggered to factor production by Fc subfragments, derived from intact Fc fragments by macrophage-dependent enzymatic cleavage. These factor(s) replace T cell function in two Fc-medi... |
6262572 | Visualization of thrombin receptors on mouse embryo fibroblasts using fluorescein-amine conjugated human alpha-thrombin. | The localization of thrombin receptors on mouse embryo (ME) cells has been examined by direct fluorescence microscopy using a fluorescein amine-labeled thrombin. Two fluorescein amines, 4-(N-2-aminoethyl thioureal)-fluorescein and 4-(N-5-aminohexyl thioureal)-fluorescein, were synthesized and attached to the carbohydra... |
6785531 | Purification of human interleukin 1. | Interleukin I (IL-1) is a lymphocyte stimulant released by human monocytes cultured for 18-24 hours in tissue culture medium containing 5% serum and the non-specific immunostimulant lipopolysaccharide (LPS). Human IL-1 is found in the conditioned medium in a low molecular weight (approximately 13,000) and a high molecu... |
7230801 | Production of insulinomimetic antibodies against rat adipocyte membranes by hybridoma cells. | SJL mice were injected intraperitoneally with adipocyte plasma membranes or with intrinsic membrane proteins obtained by extraction of plasma membranes with dimethylmaleic anhydride. Three days after the boost injection, the spleens were removed and fused with NS-a, a thioguanine-resistant myeloma cell line derived fro... |
6453255 | Evolution of membrane bioenergetics. | One of the first problems encountered by primitive cells was that of volume regulation; the continuous entry of ions, (eg, NaCl) and water in response to the internal colloid osmotic pressure threatening to destroy the cell by lysis. We propose that to meet this environmental challenge cells evolved an ATP-driven proto... |
6112288 | Visualization of the turkey erythrocyte beta-adrenergic receptor. | We have recently described the affinity chromatography purification of the turkey erythrocyte beta-adrenergic receptor. The minute amounts obtained initially precluded extensive biochemical characterization. To improve the yield of the receptor, the erythrocyte membranes have been prepared by a new method. This procedu... |
6938994 | Early appearance of methoxyflurane fluorometabolites in mice. | The biotransformation of methoxyflurane produces two fluorometabolites: inorganic fluoride (F) and an acid-labile fluorocompound (OALF). These have been assayed in the serum of male mice 10, 30, and 100 minutes after either ip or sc injections of 0.7 microliter of methoxyflurane (MOF) per gram of body weight, as either... |
6971373 | Promotion of hematopoietic stem cell differentiation in vitro by a soluble mediator, allogeneic effect factor. | This study was designed to investigate the effects of allogenic effect factor (AEF), a soluble mediator derived from short-term mixed lymphocyte cultures (MLC) of in vitro alloantigen-primed T cells, on cultures of murine bone marrow cells. Cultures established under suboptimal conditions namely, in the absence of a pr... |
7218802 | In vitro maintenance of differentiation marker synthesis by subpopulations of mouse thymocytes. | Mouse thymocyte populations enriched in functionally incompetent, "immature" cells on the one hand, or in competent "mature" cell on the other hand, express different steady-state levels of certain surface antigens and marker enzymes. In the cases of the glycoproteins H-2 (K and D), Qa, and TL, and the DNA polymerase t... |
6261044 | Hormonal regulation of the adrenocortical cell. | Monolayer cultures of bovine and human adrenocortical cells have been used to study regulation of growth and function. Homogeneous bovine adrenocortical cells exhibit a finite life span of approximately 60 generations in culture. Full maintenance of differentiated function (steroid hormone synthesis) requires an induce... |
6261043 | Cell surface receptors for endogenous mouse type C viral glycoproteins and epidermal growth factor: tissue distribution in vivo and possible participation in specific cell-cell interaction. | We have described previously the detection and tissue distribution of free cell surface receptors for ecotropic R-MuLV envelope glycoprotein and the growth factor EGF in vivo [1]. More recently, we have reported the chromosomal map position of the ecotropic viral receptor and its conservation between subspecies of the ... |
7218801 | Mapping the mitotic clock by phase perturbation. | In synchronized V79 cells perturbed by serum, heat shock, or ionizing radiation at half-hour intervals through a modal 8.5-hour cell cycle, phase-response curves show a characteristic biphasic pattern of advances and delays in subsequent cell divisions. These observations, together with previous observations of quantiz... |
7218800 | The cell substratum modulates skeletal muscle differentiation. | During chick embryogenesis, massive alterations occur in the migrating cell's substratum, or extracellular matrix. The possibility that some of the components of this milieu play a regulatory role in cell differentiation was explored in a cell-culture system derived from embryonic chick skeletal muscle tissue. In parti... |
7012452 | The in vitro synthesis and processing of the branched-chain amino acid binding proteins. | The synthesis of the leucine-specific and LIV-binding proteins was examined in vitro in a coupled transcription/translation system using the hybrid plasmids pOX7 and pOX13 as templates. Plasmid pOX7 contains the livK gene coding for the leucine-specific binding protein and pOX13 contains the livJ gene coding for the LI... |
6261042 | Interaction of polypeptide neurotoxins with a receptor site associated with voltage-sensitive sodium channels. | Anthopleurin A, a polypeptide toxin from the Pacific sea anemone Anthopleura xanthogrammica, enhances persistent activation of voltage-sensitive sodium channels by the alkaloid toxins veratridine and batrachotoxin with K0.5 = 20 nM. This effect is inhibited by depolarization. There is a close correlation between enhanc... |
7012451 | Catalytic activities associated with the enzymes II of the bacterial phosphotransferase system. | The phosphotransferase system (PTS) in Escherichia coli is a multifunctional, multicomponent enzyme system. Its primary functions deal with carbon source acquisition, while its secondary functions are concerned with the regulation of bacterial physiology. The primary functions of the system include 1) extracellular det... |
6971372 | Inhibition of alpha-bungarotoxin binding to acetylcholine receptors by antisera from animals with experimental autoimmune myasthenia gravis. | Conditions are described for an assay that allows the percent inhibition of alpha-bungarotoxin binding to acetylcholine receptors by antisera and monovalent antigen-binding fragments of antibody molecules (Fab) to be determined. Anti-Torpedo californica acetylcholine-receptor antisera, prepared in New Zealand White rab... |
6163928 | Hybrid Ia antigens: genetic, serologic, and biochemical analyses. | Ia specificities 22 and 23 were found to be determinants on hybrid Ia molecules, formed by the noncovalent binding of a 26,000--28,000 dalton beta polypeptide chain (Ae) coded by the I-A subregion and a 32,000--35,000 dalton alpha chain (E alpha) coded by the I-E subregion. For expression of Ia.23 the Ae chain, coded b... |
6261041 | H1 histone and nucleosome repeat length alterations associated with the in vitro differentiation of murine embryonal carcinoma cells to extra-embryonic endoderm. | The histone compositions and average distance between nucleosomes have been determined for F9.22 and PSA1 murine embryonal carcinoma cell lines, for primary extra-embryonic endoderm derived from the in vitro differentiation of PSA1 embryonal carcinoma cells, and for two long-term extra-embryonic endodermal cell lines. ... |
6971371 | Enhanced lymphoid and decreased myeloid reconstituting ability of stem cells from long-term cultures of mouse bone marrow. | Mature, functional lymphocytes rapidly disappear from long-term cultures of mouse bone marrow cells and never reappear. One reason for the loss of B lymphocytes is that the optimal culture conditions for maintenance of myeloid stem cells are suboptimal for lymphocyte survival. However, despite the absence of functional... |
6163927 | Total and exchangeable calcium in lymphocytes: effects of PHA and A23187. | Calcium has been suggested as an internal second messenger when lymphocytes are stimulated by mitogens to enter the cell cycle. We have assessed the effect of 2 lymphocyte stimulants, the plant lectin phytohemagglutinin (PHA) and the calcium ionophore A23187, on human lymphocyte nucleic acid synthesis, total cell calci... |
6163926 | Effects of a serum spreading factor on growth and morphology of cells in serum-free medium. | A heat-sensitive, trypsin-sensitive factor that promoted growth and spreading of cells in serum-free, hormone-supplemented medium was partially purified from human serum. The major portion of the proteins in these preparations migrated upon SDS-polyacrylamide gel electrophoresis with a mobility consistent with molecula... |
7012450 | Inhibition of cell proliferation and protease activity by cartilage factors and heparin. | Proliferating rat smooth muscle cells and fibroblasts have membrane-associated protease activity. High concentrations of heparin inhibited membrane-associated protease activity and cell proliferation, while low concentration of heparin promoted smooth muscle cell proliferation. The inhibition of protease activity and p... |
7218799 | The selective effects of charged local anaesthetics on the glucagon- and fluoride-stimulated adenylate cyclase activity of rat-liver plasma membranes. | The cationic local anaesthetics carbocaine and nupercaine were found to increase the fluoride-stimulated adenylate cyclase up to a maximum level; above this maximum level further increases in drug concentration inhibited the enzyme. At concentrations where this activity was stimulated, a fatty acid spin label detected ... |
7012449 | Endogenous and exogenous proteolysis of the acetylcholine receptor from Torpedo californica. | Purified acetylcholine receptor reconstituted into liposomes catalyzes carbamylcholine-dependent ion flux [10]. An endogenous protease activated by Ca2+ gives rise to an acrylamide gel pattern of the receptor with the 40,000-dalton subunit apparently as the major component. Exogenous proteases nick the proteins so exte... |
6971370 | H-2 I alloantigens and recall of memory cytotoxic responses. | AQR mice were immunized with H-2K and H-2 I encoded alloantigens presented by (Ax6R)F1 splenocytes. Spleen cells from these alloimmune mice were subsequently restimulated in vitro with B10.A lymphocytes and/or B10.T(6R) lymphocytes, thus presenting them with the immunizing H-2K and H-2 I alloantigens independently. Whe... |
7218798 | Characterization of monolayer and organ cultures of cloned and enriched lymphohematopoietic stroma cell populations. | The role of hematopoietic microenvironments in the regulation of maturation and differentiation of hematopoietic cells, although heavily debated, remains uncertain. Several investigators have suggested that the adherent "stromal" cell populations, which grow as colonies in cultures of lymphomyeloid tissues, include the... |
6111625 | Divalent cation dependent ATPase activities of red blood cell membranes: influence of the oxidation of membrane thiol groups close to each other. | An Mg2+-dependent low ATPase activity can be detected in erythrocyte "white membranes," in addition to that of the well known (Ca2+ + Mg2+)-ATPase. The thiol oxidizing agent diamide affects both activities. The oxidation of neighboring thiols seems to leave the mechanism of the (Ca2+ + Mg2+)-ATPase amplification system... |
7206713 | Glucocorticoid-induced lymphocytolysis: state of the genetic analysis. | The glucocorticoid-induced lysis of lymphoid cell lines offers a genetic approach to steroid hormone action because unresponsive variants can easily be selected as resistant to this lytic effect. The present state of analysis of lymphocytolysis in two murine cell lines, the S49 T-lymphoma and the W7 thymoma, is reviewe... |
7206712 | Restricted expression of an MHC alloantigen in cells of the erythroid series: a specific marker for erythroid differentiation. | The spectrum of reactivity with various types of cells of a monoclonal antibody (CH-4) which detects a private MHC antigen of chickens was analysed. CH-4 agglutinates only RBCs that possess the B2 (MHC) haplotype. A new rosette-forming cell (RFC) assay was devised to detect individual cells (excluding RBCs) that posses... |
7009990 | Evidence for a low-molecular-weight plasma peptide which stimulates chick chondrocyte metabolism. | Plasma contains a number of insulin-like activities (ILA) of molecular weights 7,000 to 90,000 (somatomedins and insulin-like proteins) which stimulate cellular metabolism and may function as growth factors. We have found evidence for the presence of an 800 Dalton peptide in human plasma which markedly stimulates the m... |
6163040 | Inhibition of lymphocyte mitogenesis by an arachidonic acid hydroperoxide. | Incubation of murine spleen cells with the oxidation product of soybean lipoxidase-treated arachidonic acid results in profound inhibition of induction of proliferation and maturation of these cells. The active entity was shown to be the 15-hydroperoxide of arachidonic acid (15-HPAA). Inhibition of the enzymes of the c... |
6451772 | The extracellular matrix and the control of proliferation of vascular endothelial and vascular smooth muscle cells. | In this short review we describe the observations which have led us to conclude that one of the most important components involved in modulating cell proliferation in vitro, and probably in vivo as well, may be the extra-cellular matrix upon which cells rest. |
7009989 | In vitro methylation of bacterial chemotaxis proteins: characterization of protein methyltransferase activity in crude extracts of Salmonella typhimurium. | A specific in vitro assay was developed for the protein carboxyl methyltransferase that is involved in the chemotactic behavior of Salmonella typhimurium. This cytosolic enzyme catalyzes an S-adenosyl-L-methionine-dependent methyl esterification of glutamyl residues on a class of 60,000-dalton inner-membrane proteins. ... |
6163038 | ATP-induced lysis of rat parotid secretory granules: possible role of ATP in exocytotic release. | Secretory vesicles isolated from a variety of mammalian tissues are known to lyse and thereby release their secretory products when exposed to ATP. This process, which will be termed ATP-induced lysis, has been studied most extensively using adrenal chromaffin-granule preparations. We report here that ATP causes the ly... |
7206711 | Cell cycle dependent rate of labelling of cellular and secreted glycosaminoglycans in mouse embryonic fibroblasts. | Cultures of embryonic fibroblasts from Balb/c or CBA/J mice were given 12-h pulses of 14C-galactose, or were double-labelled with 3H-galactose and 35H-sulfate. The time course of the rates of labelling of glycosaminoglycans--galactose label was found in the uronic acid moiety--was studied in synchronously and asynchron... |
6777606 | Uptake and binding of riboflavin by membrane vesicles of Bacillus subtilis. | Riboflavin uptake and membrane-associated riboflavin-binding activity have been investigated in Bacillus subtilis. The uptake and binding activity of the vitamin were found to be repressed coordinately by riboflavin present in the growth medium. The uptake or riboflavin has been shown to have properties of a carrier-me... |
7442256 | Light-driven primary sodium ion transport in Halobacterium halobium membranes. | Light-induced sodium extrusion from H halobium cell envelope vesicles proceeds largely through an uncoupler-sensitive pathway involving bacteriorhodopsin and a proton/sodium antiporter. Vesicles from bacteriorhodopsin-negative strains also extrude sodium ions during illumination, but this transport is not sensitive to ... |
6255257 | The scavenger cell pathway for lipoprotein degradation: specificity of the binding site that mediates the uptake of negatively-charged LDL by macrophages. | Macrophages isolated from a variety of organs in several animal species exhibit high affinity binding sites that recognize chemically modified proteins. One of these binding sites recognizes human plasma low density lipoprotein (LDL) in which the positive charges on the epsilon-amino groups of lysine have been removed ... |
7442255 | The association of alpha-actinin with the plasma membrane. | The role of alpha-actinin in the attachment of actin to plasma membranes has been investigated. Specific antibody staining of SDS gels has indicated that alpha-actinin is a major component in isolated plasma membranes prepared from three different cell types by two different procedures. Using specific extraction condit... |
7442254 | A comparative dielectric study of human serum low density lipoprotein before and after partial digestion by trypsin. | The relative permittivity of aqueous solutions of human serum low density lipoprotein (LDL) and partially trypsin digested lipoprotein (T-LDL) has been determined for various concentrations at 20 degrees C over the frequency range 0.15-100 MHz. Comparison of the dielectric dispersion curves for the digested lipoprotein... |
7442253 | Steroid hormone receptor studies in melanoma model systems. | The transplantable B-16 melanotic melanoma carried in syngeneic C57Bl/6J female mice and the Syrian hamster melanoma cell line, RPMI 3460, were utilized to determine whether steroid-hormone receptors are present in animal melanomas. In the B-16 melanoma, a cytoplasmic-estrogen receptor is detectable, but there is no ev... |
6160320 | An axial periodic fibrillar arrangement of antigenic determinants for fibronectin and procollagen on ascorbate treated human fibroblasts. | Fibronectin and collagens are major constituents of the cell matrix of fibroblasts. Fibronectin is a 220,000 dalton glycoprotein that mediates a variety of adhesive functions of cells examined in vitro. Fibronectin is secreted in a soluble form and interacts with collagen to form extracellular filaments. Fibronectin an... |
6449635 | Cloning of the histidine transport genes from Salmonella typhimurium and characterization of an analogous transport system in Escherichia coli. | The genes for the well-characterized high-affinity histidine transport system of S typhimurium have been cloned in lambda gt4. Genetic and physiological analyses of the analogous transport system of E coli were undertaken in order that available lambda vectors, recombinant DNA techniques, and a genetic selection for tr... |
7003263 | The role of the Escherichia coli lambda receptor in the transport of maltose and maltodextrins. | The lambda receptor is a peptidoglycan-associated integral protein that spans the outer membrane. Beside its function in phage lambda adsorption it participates in transport. The latter function can be summarized as follows: 1) Receptor allows the nonspecific permeation of small molecules other than maltose and maltode... |
6449634 | Analysis of human erythrocyte membrane vesicles produced by shearing. | Shearing of ghosts in a French pressure cell produces three classes of microvesicles that differ from endocytic vacuoles, exocytic vacuoles, and inside-out vesicles. It was thought that an analysis of these vesicles might provide some clues about the assembly of proteins within the human erythrocyte membrane. The micro... |
7190424 | Intestinal absorption of 14C-labelled beta-cyclodextrin in rats. | beta-Cyclodextrin and glucose labelled universally by 14C was administered orally to rats and blood radioactivity level was followed. In the case of glucose about 20% of the administered radioactivity, related to 10 ml blood was to be found and this appeared in the blood within 10 min following the oral administration.... |
6929727 | Antitumor activity of benzaldehyde. | Ninety patients with inoperable carcinoma in the terminal stages and 12 patients in serious condition with other tumor types were given benzaldehyde in the form of beta-cyclodextrin benzaldehyde inclusion compound (CDBA) orally or rectally at a daily dose of 10 mg/kg divided in four doses. Toxic effects, including hema... |
6892771 | Interaction of aldolase with actin-containing filaments. Structural studies. | Electron micrographs of the paracrystals formed when fructose bisphosphate aldolase (EC 4.1.2.13) is added to actin-containing filaments were analysed by computer methods so that ultrastructural changes could be correlated with the various stoicheiometries of binding determined in the preceding paper [Walsh, Winzor, Cl... |
6245244 | Transfection of molecularly cloned Friend murine leukemia virus DNA yields a highly leukemogenic helper-independent type C virus. | Unintegrated viral DNA was isolated via the Hirt procedure from mouse fibroblasts newly infected with Friend murine leukemia virus (F-MuLV) clone 201, a biologically cloned helper virus isolated from stocks of F-MuLV complex. A physical map of the unintegrated in vivo linear viral DNA was generated for several restrict... |
6988606 | Role of the host cell in bacteriophage T4 development. I. Characterization of host mutants that block T4 head assembly. | To study the role of the host cell in bacteriophage T4 infection, we selected more than 600 mutant host-defective bacteria that absorbed and were killed by phage T4+ but were unable to support its growth. The mutants were grouped into seven classes by the growth patterns of T4 phages carrying compensating mutations (go... |
6245226 | Herpes simplex virus phosphoproteins. I. Phosphate cycles on and off some viral polypeptides and can alter their affinity for DNA. | We report on phosphorylation, the stability of the bound phosphate, and the properties of several phosphorylated infected-cell polypeptides (ICPs) synthesized in cells infected with herpes simplex virus 1 and 2. Our results and conclusions are as follows. (i) Phosphorylation of ICPs occurs by at least two different pat... |
6245225 | Protein-protein interactions within paramyxoviruses identified by native disulfide bonding or reversible chemical cross-linking. | Analysis of native disulfide-bonded protein oligomers in paramyxoviruses showed that some viral proteins are consistently present as covalent complexes. In isolated Sendai virus the hemagglutinating protein HN is present in homodimeric and homotetrameric forms, and the minor nucleocapsid protein P exists partly as a mo... |
6965931 | Oxygen effect in the radiolysis of proteins. I. Lactate dehydrogenase. | Dose survival curves of lactate dehydrogenase irradiated under aerobic and anaerobic conditions show a sensitizing effect of oxygen for the inactivation of the enzyme. The oxygen effect in the radiolysis of lactate dehydrogenase was analysed by gel filtration and polyacrylamide gel electrophoresis. Under anaerobic cond... |
6444789 | Multiple organ failure: clinical and experimental. | The clinical scenario of multiple organ failure (MOF) is reviewed and its frequent correlation with sepsis emphasized. It is hypothesized that MOF is produced by the formation of immune complexes (IC) in response to infection with deposition on organs such as the liver, lung, and kidney. Such immune complexes trap macr... |
6444720 | Specificity of diffusion channels produced by lambda phage receptor protein of Escherichia coli. | The lamB protein, the receptor for phage lambda, was purified from the outer membrane of Escherichia coli K-12 by extraction with Triton X-100 and EDTA, chromatography on DEAE-Sephacel in Triton X-100, exchange of Triton for cholate by gel filtration, and chromatography on Sephacryl S-200 in cholate, NaCl, and EDTA. Th... |
7357605 | The nuclear envelope lamina is reversibly depolymerized during mitosis. | The nuclear envelope lamina is a supramolecular protein assembly associated with the nucleoplasmic surface of the inner nuclear membrane, which contains three predominant polypeptide components in mammalian cells (lamins A, B and C). We previously demonstrated by immunofluorescence microscopy that the lamina is reversi... |
7356977 | Supramolecular organization of chlorosomes (chlorobium vesicles) and of their membrane attachment sites in Chlorobium limicola. | The photosynthetic green bacterium Chlorobium limicola 6230 has been examined by freeze-fracture electron microscopy to investigate the size, form, distribution and supramolecular architecture of its chlorosomes (chlorobium vesicles) as well as the chlorosome attachment sites on the cytoplasmic membrane. The oblong chl... |
6153465 | Structural requirements for binding of bovine tRNATrp with avian myeloblastosis virus DNA polymerase. | Avian DNA polymerases use host tRNATrp as the primer for transcription. Bovine tRNATrp has been previously shown to be a biologic substitute for the avian primer. A bovine tRNATrp fragment has been identified as having a high binding affinity for the polymerase. The fragment is assigned to be 67 nucleotides, and contai... |
7355128 | Self-assembly of single and closely spaced nucleosome core particles. | Self-assembly of DNA with the four core histones but in the absence of H1 generates nucleosome core particles which are spaced randomly over large distances. Closely spaced core particles, however, exhibit a preferred short linkage which is not a multiple of 10 base pairs. They bind about 140 base pairs whereas apparen... |
7354125 | Pharmacokinetic properties of human fibroblast and leukocyte interferon in rabbits. | When rabbits were given intramuscular injections of the same quantities of human leukocyte or fibroblast interferons, the former produced moderately higher levels of circulating interferon. Fibroblast interferon was not cleared faster from circulation, nor was direct inactivation by rabbit blood responsible for this di... |
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