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S Champion

Publications and source records attributed to S Champion.

44 records · Page 3Linked to original sources
PubMed1976

Relationship between prostaglandin biosynthesis and the effect of insulin on hormone-stimulated lipolysis in rat adipose tissue.

Lipolysis in rat fat pads was studied by determination of free fatty acid and glycerol production in various experimental conditions (in the absence or presence of glucose, adrenalin and insulin). These results were compared to the accumulation of endogenous prostaglandins E2 and F2alpha during lipolysis. In the absence of glucose the prostaglandin production followed the adrenalin-induced fluctuations in released free fatty acids both in the presence or absence of insulin. In the presence of glucose and insulin, a drop in prostaglandin accumulation was observed whereas free fatty acids production was strongly stimulated. These results suggest that either free fatty acid composition is modified, influencing the activity of prostaglandin synthetase, or that there exists a specific mechanism controlling prostaglandin synthesis.

Adipose Tissue↗
PubMed1976

Stimulation by TSH of prostaglandin synthesis in pig thyroid.

The liberation of arachindonate in the thyroid occurs at the expense of two distinct pools of precursors. (1) the phosphatidylinositol through a process Ca2+-dependent and cyclic AMP-independent; and (2) the triglycerides by a cyclic AMP-dependent lipase, in which the involvement of cyclic AMP-dependent protein kinase has not yet been determined. The "PI pool" or "paracyclic AMP pool" is mobilized very rapidly by large doses of TSH but its physiological significance can be discussed. The "triglyceride pool" or "post-cyclic AMP pool" is mobilized more slowly by small doses of TSH and seems not to be implicated in the acute TSH stimulation of adenylate cyclase. The "post-cyclic AMP pool" of prostaglandins would be very important as third messenger or as "long-acting TSH hormone". Some recent works of Boeynaems and Van Sande (16) and Madaoui et al. (17) on the thyroid support this hypothesis, as aspirin or indomethacin inhibits DBc-AMP stimulation of glucose oxydation, iodine organification, or thyroid hormone secretion. On the other hand, in the absence of prostaglandin synthesis, TSH still stimulates the adenylate cyclase, which means that prostaglandins are not obligatory intermediates of hormonal action on cyclic AMP production. In conclusion, these results show a TSH action in the thyroid on the release of fatty acids, precursors of PG's, from their lipidic stores. Nevertheless, a second control step is not excluded in conversion of cyclic endoperoxide to PGE or PGFalpha.

Animals↗
PubMedDate not supplied

The effects of ribavirin on the GTP level and the VIP receptor dynamic of human IGR39 cells.

GTP is one of the major cellular molecules involved in fundamental functions of cell life. Ribavirin, and antiviral and antitumoral agent, the primary site of action of which is the IMP deshydrogenase, was used in order to depress the intracellular GTP level. Consequential effects were tested on the property and dynamic of the VIP receptor on human melanoma IGR 39 cells. A concentration of 100 microM of Ribavirin reduced the intracelluar GTP level by more than 60% and induced a reversible growth arrest. Nevertheless this drug displayed no effect on: i) the VIP binding parameters (Kd and Bmax) of both high and low affinity receptors; ii) the cycling of the VIP receptor; iii) the based and VIP-stimulated cAMP production and iv) the subcellular GTP distribution. We show that Ribavirin, in the range of concentrations used, is very efficient to inhibit GTP synthesis in the human melanoma cell line IGR 39 and its growth, without affecting VIP receptor functions.

Adenosine Triphosphate↗