Search PubMed⌕ Search

Biomedical subjects

L Glaser

Publications and source records attributed to L Glaser.

At least 91 records · Page 5Linked to original sources
PubMed1979

Effect of plasma membranes on solute transport in 3T3 cells.

Sparse cultures of Swiss 3T3 cells are arrested early in the G1 phase of growth by the addition of a plasma membrane fraction obtained from confluent 3T3 cells. We have examined whether the changes in solute transport which are usually associated with cessation of growth at confluency also take place when cell growth is arrested by the addition of plasma membranes. We find that the rate of uptake of alpha-aminoisobutyric acid and uridine is decreased after the addition of plasma membranes to 3T3 cells, but the rate of uptake of 2-deoxyglucose and phosphate is not. We conclude from these observations that uptake of uridine and alpha-aminoisobutyric acid are related to contact inhibition of growth, while the decline in the rate of uptake of 2-deoxyglucose and phosphate observed at high cell density must be due to changes other than cell to cell contact.

Aminoisobutyric Acids↗
PubMed1979

Regulation of teichoic acid synthesis during phosphate limitation.

Bacillus subtilis W-23, when placed in phosphate-free medium, ceases to synthesize teichoic acid and synthesizes teichuronic acid. The enzymatic basis for the cessation of teichoic acid synthesis is the irreversible inhibition of the first membrane-bound enzyme involved in teichoic acid synthesis which catalyzes the reaction Undecapenol-P + UDP-GlcNAc leads to undecaprenol-P-P-GlcNAc + UMP.

Bacillus subtilis↗
PubMed1979

The relation of temperature and lipid composition to cell adhesion.

We have examined as a function of temperature the effect of changes in the composition of the fatty acid chains of membrane phospholipids on the rate of cell to cell adhesion in the neuronal cell line B103. The rate of cell to cell adhesion in this cell line is highly temperature dependent but is not influenced by changes in the fatty acid composition of the plasma membrane generated by growing the cells either in the presence of oleic acid or elaidic acid. In contrast the temperature dependence of the rate of cell to cell adhesion, measured in a monolayer adhesion assay, is highly dependent on the shear force used during the assay. A two-step model of cell to cell adhesion involving multiple adhesion ligands is presented which can be used to explain these observations.

Cell Adhesion↗
PubMed1979

Regulation of the cell cycle of 3T3 cells in culture by a surface membrane-enriched cell fraction.

Addition of a suspension of a surface membrane enriched fraction prepared from confluent 3T3 cells to sparse 3T3 cells in culture results in a concentration dependent and saturable decrease in the rate of DNA synthesis. The inhibition of cell growth by membranes resembles the inhibition of cell growth observed at confluent cell densities by a number of criteria: 1) In both cases the cells are arrested in the G1 portion of the cell cycle; 2) the inhibition by membranes or by high local cell density can to a large extent be compensated for by raising the serum concentration or by addition of fibroblast growth factor plus dexamethasone. Membranes prepared from sparse cultures inhibit less well than membranes from confluent cultures in a manner which suggests that binding of membranes to cells is not by itself sufficient to cause inhibition of cell growth. The inhibitory activity has a subcellular distribution similar to phosphodiesterase (a plasma membrane marker) and appears to reside in one or more intrinsic membrane components. Maximally, membranes can arrest about 40% of the cell population in each cell cycle. Plasma membranes obtained from sparse 3T3 cells are less inhibitory than membranes obtained from confluent cells. This suggests either that the inhibitory component(s) in the plasma membrane responsible for growth inhibition may be in part induced by high cell density, or that this component(s) may be lost from these membranes during purification.

Animals↗
PubMed1979

Growth control by cell to cell contact.

Control of cell growth by cell to cell contact is reviewed with particular emphasis on two systems--contact inhibition of growth observed with Swiss 3T3 cells and the mitogenic stimulation of Schwann cells by dorsal root ganglia neurites. In both cases the biological effect can be reproduced by the addition of surface membranes to the corresponding cells. In the case of contact inhibition of 3T3 cells, biological activity appears to correlate with membrane binding to the cells. An octylglucoside extract of 3T3 plasma membranes retains the biological activity (growth inhibition) of the original membranes.

Aminoisobutyric Acids↗
PubMed1979

Tetrodotoxin-sensitive sodium channels in normal human fibroblasts and normal human glia-like cells.

Tetrodotoxin-sensitive sodium channels are detectable in normal human fibroblasts and in "glia-like" cells at appreciable levels when compared to what is observed in established neuronal cell lines in culture. Two- to 3-fold stimulations of sodium influx are observed in the presence of 0.2 mM veratridine and scorpion venom at 0.1 mg/ml. Tetrodotoxin (2 microM) inhibits the observed stimulation of sodium influx. Previous work has indicated that these neurotoxins act on the voltage-sensitive sodium ionophore of excitable cells, and the presence of such channels in cells generally considered nonexcitable raises questions regarding both the uniqueness of this ionophore as a property of excitable cells and the origin of the cells generally described as fibroblasts.

Cell Line↗
PubMed1979

Control of teichoic acid synthesis during phosphate limitation.

The synthesis of teichoic acids was examined in Bacillus subtilis Marburg grown under conditions of phosphate limitation. The results indicate that the inhibition of polyglycerolphosphate synthesis observed under these conditions is the result of two processes. The first process is reversible and is independent of new protein synthesis; the second process is irreversible and requires the synthesis of new protein. During growth, under conditions of phosphate limitation, there is a slow decrease in the level of CDP glycerol pyrophosphorylase activity which is by itself not sufficient to account for the decrease in the rate of polyglycerolphosphate synthesis.

Bacillus subtilis↗
PubMed1978

Inhibition of growth of 3T3 cells by extract of surface membranes.

The growth of Swiss 3T3 cells can be inhibited by the addition of a plasma membrane enriched fraction from 3T3 cells [Whittenberger, B & Glaser, L. (1977) Proc. Natl. Acad. Sci. USA 74, 2251--2255]. We report conditions for the extraction of the inhibitory components from the membranes with octylglucoside. The solubilized components reversibly inhibit the rate of cell division of 3T3 but not of simian virus 40-transformed 3T3 cells. The inhibitory activity is heat labile and nondialyzable. The inhibition observed with the soluble extract can be reversed by mitogenic factors present in serum.

Cell Division↗
PubMed1978

Specific glycoprotein changes during development of the chick neural retina.

After separation of whole proteins of chick neural retina by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS), a number of glycoproteins can be detected by staining the gels with 125I-labeled wheat germ agglutinin (WGA) and other lectins. The glycoprotein patterns show both quantitative and qualitative changes between days 7 and 13 of development. Some of these glycoproteins can be separated by chromatography on columns of insolubilized lectins. These observations suggest that purification of some of these glycoproteins identified by staining with radioactive lectins would yield retinal antigens which may be specific for developmental stage and cell type.

Animals↗
PubMed1977

Inhibition of DNA synthesis in cultures of 3T3 cells by isolated surface membranes.

When added to a sparse culture of 3T3 cells, a surface membrane-enriched fraction from 3T3 cells inhibited the rate of DNA synthesis in a time- and concentration-dependent manner. The membrane preparation had no effect on the rate of DNA synthesis of simian virus 40-transformed 3T3 cells. A similar membrane preparation from transformed cells had a lesser inhibitory effect on 3T3 cells and no effect on transformed cells. The inhibition by membranes was reversible. The data suggest that, when added to growing 3T3 cells, 3T3 surface membranes can mimic the effect of increasing cell density on DNA synthesis.

Cell Line↗