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Biomedical subjects

B Jeanrenaud

Publications and source records attributed to B Jeanrenaud.

At least 217 records · Page 12Linked to original sources
PubMed1974

Effects of cytochalasin B, colchicine and vincristine on the metabolism of isolated fat-cells.

1. Colchicine and vincristine only slightly inhibit the metabolism of glucose to CO(2) and lipids by isolated fat-cells. 2. Prolonged incubation with these agents causes no further inhibition. 3. Cytochalasin B, however, inhibits glucose metabolism to both CO(2) and lipids in fat-cells. 4. However, at a concentration that causes a strong inhibition of glucose metabolism cytochalasin B is without effect on the metabolism of pyruvate, lactate or arginine to these end products. The uptake of labelled alpha-aminoisobutyrate is likewise not modified. Similarly it does not affect release of glycerol or free fatty acid, or the actions of adrenaline, insulin or caffeine on these parameters. At 10mug/ml it slightly lowers ATP concentrations, an effect that does not occur at 2mug/ml. 5. The transport of fructose into adipocytes by a specific fructose-transport system is also not affected by the agent, but the uptake of 2-deoxyglucose is strongly inhibited. It is concluded that cytochalasin B may specifically inhibit the glucose-transport system of isolated fat-cells. 6. Cytochalasin A has a much weaker action than cytochalasin B on glucose metabolism.

Adenosine Triphosphate↗
PubMed1974

Evidence for a role of the microtubular system in the secretion of newly synthesized albumin and other proteins by the liver.

Livers of normal mice were prefused in situ and the secretion of newly synthesized (i.e. labeled) proteins into the perfusate were measured. In control livers, the secretion of newly synthesized proteins was found to be linear with time. In marked contrast, when livers were perfused with vinblastine, vincristine, or colchicine, drugs known to interfere with the hepatic microtubular system, the release of newly synthesized proteins was either strongly inhibited or completely suppressed although total hepatic protein synthesis (estimated by the incorporation of labeled amino acids into hepatic plus perfusate proteins) remained unaltered. Chromatographic separation of the various secreted proteins showed that the release of albumin, globulins, and small polypeptides was decreased to a similar extent by vincristine or colchicine. In the particular case of albumin, it was further observed that total (i.e. liver plus perfusate) labeled amino acid incorporation into albumin was not altered by either vincristine or colchicine, whereas the incorporation of these amino acids into liver albumin was markedly increased but incorporation into perfusate albumin was decreased, suggesting that the translocation of this particular protein from the liver to the perfusate had been affected by the presence of these drugs. It is proposed that the functional integrity of microtubules is necessary for the intracellular movement and eventual release of albumin and other proteins by the liver, and suggested that microtubules might possibly be a site of regulation of hepatic protein secretion.

Albumins↗
PubMed1973

Cell-associated nonesterified fatty acid levels and their alteration during lipolysis in the isolated mouse adipose cell.

A rapid and flexible method has been developed for measuring cell-associated, probably intracellular, nonesterified fatty acids (CAFA) in isolated mouse adipose cells. A variety of lipolytic agents as well as various concentrations of epinephrine elevate CAFA levels in rough proportion to their stimulation of glycerol and fatty acid release. Insulin reduces epinephrine-elevated CAFA levels. A detailed, quantitative study of the relationship among lipolytic activity, CAFA levels, and the extracellular molar ratio of fatty acids to albumin has been carried out. Epinephrine-elevated CAFA levels rise linearly with, while epinephrine-stimulated lipolytic activity is independent of, fatty acid to albumin ratios below 2-3. As the ratio increases from 3 to 5, CAFA levels continue to increase, whereas lipolytic activity decreases. Above ratios of 5, fatty acid release almost completely ceases; CAFA levels increase dramatically with residual glycerol release. A temperature-dependent efflux of epinephrine-elevated CAFA can be elicited through blockade of stimulated lipolysis with propranolol, but only in the presence of extracellular fatty acid to albumin ratios below 3. These observations suggest that during stimulated lipolysis, a fatty acid gradient exists between the cell and extracellular serum albumin and that CAFA represent the intracellular component of this gradient. In addition, these observations support the concept that intracellular fatty acids play a role in the feedback regulation of adipose cell function as extracellular fatty acids accumulate during the lipolytic response.

Adipose Tissue↗