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Biomedical subjects

V Bosch

Publications and source records attributed to V Bosch.

At least 55 records · Page 3Linked to original sources
PubMed1981

In vitro transformation with Rous sarcoma virus and the pp60src-associated protein kinase.

Fifteen transformation defective sensitive mutants of Rous sarcoma virus have been investigated to see if the expression of the pp60src-associated protein kinase activity correlated with other parameters of transformation such as altered growth control, morphological changes, increased hexose transport, and increased plasminogen activator protease synthesis. The expression of a protein kinase activity paralleled or preceded the onset of other parameters of transformation with but one exception: altered control of cell growth. The stability of the pp60src molecule in mutant-infected cells at the nonpermissive temperature was investigated with the finding that mutant pp60src did not show an increased turnover at the nonpermissive temperature as compared to wild type virus pp60src. Furthermore, it could be shown that pre-existing pp60src in mutant-infected cells maintained at the non-permissive temperature became activated after temperature shift to the permissive temperature. Temperature shift performed under conditions of inhibition of new protein synthesis with cycloheximide, puromycin, or emetine was followed by greatly increased protein kinase activity, and a parallel phosphorylation of pp60src itself in tyrosine residues. Morphological features of transformation could be demonstrated likewise under conditions of inhibition of protein synthesis.

Animals↗
PubMed1978

Study of group-specific proteins in mammalian cells transformed by Rous sarcoma virus.

Lysates of various mammalian RSV-transformed cells labelled with 35S-methionine were tested for the presence of gs proteins and for the size of these molecules by means of antisera, using sodium dodecyl sulphate--polyacrylamide slab gel electrophoresis. In no case was the presence of gs proteins detected in the analyzed immunoprecipitates; only in RSH-mix cells a quantitative difference in the contrast of a 70 000-molecular weight protein was found. The autoradiograms of simultaneously tested immunoprecipitates of lysates of RSV-transformed chicken cells clearly showed the presence of p27 and after a short-term labelling also of the gs precursor molecule (pr76). The cause of the failure in detecting gs proteins by the used method in two mammalian RSV-transformed lines, in which the gs antigens were previously detected by complement fixation test, are discussed.

Avian Sarcoma Viruses↗
PubMed1976

Lipid transport across the intestinal epithelial cell. Effect of colchicine.

Rats injected with colchicine (0.5 mg/100 g of body weight) 1 h before ingestion of a margarine emulsion (1 g in 2 ml of saline) do not show the rise in plasma triacylglycerol concentration found in controls during the subsequent hours. The effect of colchicine is more dramatic when the experiment is performed after prior administration of Triton WR-1339, a substance known to inhibit the catabolism of lipoproteins. Colchicine-treated rats also showed a five-fold increase in the content of triacylglycerol in proximal jejunum, when compared to controls. These results are consistent with the idea that colchicine interferes with the intracellular phase of fat absorption, suggesting that the microtubular-microfilamentous system could be involved in the release of chylomicrons from the intestinal cell into the circulation.

Animals↗
PubMed1976

Antigenic determinants of murein lipoprotein and its exposure at the surface of Enterobacteriaceae.

Murein lipoprotein from the outer membrane of Escherichia coli could be fixed to erythrocytes without pretreatment of the erythrocytes. Passive hemagglutination or immune hemolysis could thus be used as sensitive assays to determine antibodies against lipoprotein. In rabbit antisera prepared against whole cells of E. coli, Salmonella, Arizona, and Shigella antibodies against lipoprotein were present. The respective titers were lowest in encapsulated smooth strains and highest in rough mutants. Antisera against deep rough mutants showed even higher anti-lipoprotein titers than anti-R-lipopolysaccharide titers. Correspondingly,absorption of lipoprotein antibodies with enterobacterial strains was most pronounced with deep rough mutants and lowest with smooth strains. Lipoprotein becomes increasingly an immunogen as well as an antigen the more sugar residues are missing in the lipolysaccharide on the cell surface. In wild-type cells lipoprotein is buried in the outer membrane; its exposure in mutant cells is related to defects at the cell surface.

Animals↗
PubMed1973

Early changes in plasma lipoprotein structure and biosynthesis in cholesterol-fed rabbits.

Plasma lipoproteins of d < 1.063 g/ml from rabbits fed a diet containing 1% cholesterol for 4 days showed changes in concentration and rates of flotation as determined by analytical ultracentrifugation. A marked increase in cholesteryl ester content of lipoprotein with d < 1.019 g/ml was the most prominent change in rabbits fed the diet for 21 days. Gel electrophoresis and immunochemical procedures demonstrated that in control and hypercholesterolemic rabbits there were some common apolipoproteins found in all lipoproteins with density < 1.063 g/ml. In control rabbits, there were also apolipoproteins specific to the lipoprotein fraction with d < 1.019 and to the fraction with d 1.019-1.063 g/ml. However, in rabbits fed the hypercholesterolemic diet for 21 days, the apolipoproteins characteristic of fraction 1.019-1.063 were the most abundant in the fraction with d < 1.019 g/ml. Liver slices from rabbits fed the high cholesterol diet for 7 and 21 days incorporated more l-[(14)C]leucine into very low density and low density lipoproteins than controls. The results suggest that cholesterol feeding leads to an increase in biosynthesis of lipoproteins with d < 1.063 g/ml. The newly synthesized lipoprotein contains apolipoproteins similar to those found in controls but with a higher lipid-to-protein ratio. From the apoprotein composition, it is concluded that the very low density fraction present in cholesterol-fed animals is more structurally related to low density lipoproteins than to the very low density lipoproteins isolated from control animals.

Animals↗
PubMed1972

Repetitive sequences in the murein-lipoprotein of the cell wall of Escherichia coli.

The amino-acid sequence of the murein-lipoprotein of the Escherichia coli cell wall is presented. This protein is covalently bound to a lipid component as well as to the murein (peptidoglycan, mucopeptide). The sequence is also highly repetitive. At the N-terminal portion, there are three adjacent almost identical sequences, indicating repeated duplication of a gene coding originally for 15 amino acids. The C-terminal part of the polypeptide chain is more variable but still shows striking homology when certain sequence gaps are introduced. The lipid is bound to the N-terminal serine of the dipeptide (Ser-Ser) that extends from the repetitive sequence. At the C-terminal end where the murein is bound, a tripeptide extends from the repetitive portion. Here there are several basic amino acids and the only aromatic amino acid in the lipoprotein. The sequence is Lys-Tyr-Arg-Lys. The linkage to the murein is formed between the epsilon-amino group of the C-terminal lysine and the carboxyl group of the optical L-center of meso-diaminopimelic acid. The polypeptide chain is composed of 57 amino acids and lacks glycine, proline, cysteine, phenylalanine, histidine, and tryptophan. 63% of the amino acids are hydrophilic, but because of the covalently linked lipid this structural membrane protein has very hydrophobic properties.

Amino Acid Sequence↗
PubMed1971

A method for the determination of lipoprotein lipase in postheparin plasma and body tissues utilizing a triolein-coated Celite substrate.

A simple and specific method for assaying lipoprotein lipase activity is described. Postheparin plasma, heart homogenates, or extracts of acetone powder of adipose tissue were incubated with a triolein-coated Celite substrate, and enzyme activity was determined from the rate of free fatty acid (FFA) release in the incubation system. FFA release was linear for 30 min, and was proportional to protein concentration in the incubation system. FFA release was decreased by addition of deoxycholate or Triton X-100. Increasing the concentration of heparin in the incubation system caused a gradual decrease in FFA release by postheparin plasma and increases in activity of heart homogenates and adipose tissue lipoprotein lipase. The Celite substrate was found to be satisfactory for assaying pancreatic lipase activity as well.

Adipose Tissue↗
PubMed1967

Serum lipoproteinemia in pregnant and lactating rats.

Serum lipoproteins of pregnant and puerperal rats were studied by preparative and analytical ultracentrifugation. The concentration for the fraction with density less than 1.019 was markedly elevated in rats during the 3rd wk of gestation and in lactating rats. This fraction showed similar triglyceride fatty acid composition and immunoelectrophoretic behavior whether it was derived from pregnant or nonpregnant rats, and when partially delipidized, the lipoproteins from both groups showed similar immunoelectrophoretic characteristics and sedimentation rates. When lactation was interrupted during puerperium, serum lipoproteins returned to control levels; but in lactating rats, high levels of serum very low density lipoprotein persisted up to 3 wk post partum.

Animals↗