Biomedical subjects

P Mavier

Publications and source records attributed to P Mavier.

57 records · Page 4Linked to original sources

PubMedDate not supplied

In vitro toxicity of hydrogen peroxide against normal vs. tumor rat hepatocytes: role of catalase and of the glutathione redox cycle.

Hydrogen peroxide produced by stimulated phagocytic cells or during the metabolism of drugs, is toxic to various cell types. The aim of this study was to investigate its toxicity against normal vs. tumor rat hepatocytes. Isolated normal hepatocytes and tumor hepatocytes from three hepatocarcinoma cell lines, Fao, C2 (Faof1C2) and HTC, were incubated in the presence of a H2O2-generating system consisting of glucose and varied concentrations of glucose oxidase. The toxicity of H2O2 was quantified by measuring the percentage of lactate dehydrogenase activity released in the culture medium after various times of incubation. By comparison to normal hepatocytes, tumor hepatocytes exhibited an increased susceptibility to lysis by H2O2. At a concentration of 100 mU per ml, glucose oxidase induced a lactate dehydrogenase activity release of only 6.1 +/- 2.2% (mean +/- S.E.) from normal hepatocytes and of 71.0 +/- 2.9, 45.5 +/- 2.5 and 34.7 +/- 3.4% from Fao, C2 and HTC cells, respectively, after an 18-hr incubation. At a concentration of 10 mU per ml, glucose oxidase had no toxic effect to normal hepatocytes or HTC cells, whereas it induced a lactate dehydrogenase activity release of 58.7 +/- 7.6 and 51.2 +/- 5.6% from Fao and C2 cells, respectively. In addition, the time courses of lactate dehydrogenase activity release, studied with 500 mU per ml glucose oxidase, demonstrated that Fao cells, C2 cells and, to a lesser degree, HTC cells were lysed more rapidly than normal hepatocytes. The toxicity of glucose oxidase was suppressed by the addition of catalase, indicating that it was actually mediated by H2O2.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

Increased release of lymphokines by allografted mouse spleen cells following concanavalin A stimulation.

Using a test proposed in this laboratory for following macrophage "activation" (intracellular beta-glucuronidase content) and quantitative dilution studies, we have shown that lymphocytes from mice presensitized by a skin allograft release far more macrophage activating lympholines than do normal lymphocytes when non-specifically stimulated by concanavalin A. This difference may be due to latent metabolic changes of sensitized lymphocytes, but it may also express a modified balance among the various lymphocyte subpopulations within the spleen of grafted mice.

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PubMedDate not supplied

[Comparative study of pinocytosis and the production of prostaglandin E2 by hepatic and peritoneal resident macrophages in mice].

Pinocytosis and prostaglandin E2 production are two major functions of the mononuclear phagocyte system. The goal of this study was to compare the pinocytosis of horseradish peroxidase and the prostaglandin E2 production between the hepatic and peritoneal resident macrophages in the mouse. Hepatic resident macrophages were isolated by collagenase digestion, differential centrifugation and adherence. Peritoneal resident macrophages were isolated by peritoneal cavity washing followed by adherence. Horseradish peroxidase was endocytosed by hepatic macrophages at a significantly higher rate (118 +/- 12 ng/10(6) cells/60 min) than by peritoneal macrophages (21 +/- 4 ng/10(6) cells/60 min). Prostaglandin E2 production was measured in the culture medium of unstimulated and lymphokine-stimulated hepatic and peritoneal resident macrophages. Prostaglandin E2 concentration in the culture medium of unstimulated peritoneal macrophages was 36.6 +/- 26.8 ng/ml after a 24 h incubation. It was increased by 83 p. 100 in presence of a lymphokine-enriched secondary mixed lymphocyte culture supernatant. In contrast, hepatic macrophages did not produce any significant amount of prostaglandin E2, even if they were incubated in presence of lymphokines. This study shows that hepatic resident macrophages have a higher pinocytic capacity than peritoneal resident macrophages, suggesting that the role of the liver in the clearance of gut-derived antigens is not only due to its portal irrigation but also to the presence of macrophages highly differentiated in their endocytotic properties. The lack of prostaglandin E2 production in hepatic macrophages, in basal conditions as well as after lymphokine-stimulation, suggests that these cells play a minor role in the regulation of the immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

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