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Biomedical subjects

M Chevalier

Publications and source records attributed to M Chevalier.

At least 19 recordsLinked to original sources
PubMed1992

In vitro androgenic induction of a major protein in epithelial cell subcultures from mouse vas deferens.

Pure epithelial cell cultures, obtained from primary culture of vas deferens tissue collected from 20- to 30-day-old mice, were amplified by subculturing the cells over 3T3 feeder layer in a serum-free defined medium. Adhesion and proliferation of epithelial cells did not require androgens, but a minimal concentration of 5.10(-7) M hydrocortisone. In that system, epithelial cells expressed cytokeratin but failed to produce the tissue specific mouse vas deferens protein (MVDP) in response to androgens. Various culture procedures and medium compositions were assayed for induction of MVDP expression. Culture onto microporous membrane inserts, which allow polarization of cells, is absolutely required for androgenic induction of MVDP. Androgen action did not require the presence of hydrocortisone, insulin, triiodothyronine, pituitary extracts, epidermal growth factor and acetylcholine. A minimal supplemented medium was then defined in which the expression of MVDP by epithelial cells in response to androgens was dose dependent. It has also been shown that this response at each concentration of dihydrotestosterone was heterogeneous at individual cell level. Highly reproducible results were obtained from epithelial cell cultures between 8th to 16th passages, showing that subcultured cells have maintained their ability to differentiate and express specialized functions.

Acetylcholine↗
PubMed1990

Hydrogen peroxide mediates the oxidative inactivation of enzymes following the switch from anaerobic to aerobic metabolism in Klebsiella pneumoniae.

Klebsiella pneumoniae utilizes distinct pathways for the anaerobic and aerobic metabolism of glycerol. During anaerobic growth, glycerol is first converted to dihydroxyacetone by glycerol dehydrogenase; subsequent phosphorylation yields dihydroxyacetone phosphate. During aerobic growth, glycerol is initially phosphorylated to yield glycerol 3-phosphate; subsequent reduction then gives dihydroxyacetone phosphate. A coordinated response occurs when anaerobically growing cells are switched to aerobic conditions. Synthesis of glycerol dehydrogenase is repressed, glycerol dehydrogenase is inactivated, and the protein is degraded. Ethanol dehydrogenase and propanediol oxidoreductase are also inactivated when cells are exposed to oxygen (Johnson, E. A., Levine, R. L., and Lin, E. C. C. (1985) J. Bacteriol. 164, 479-483). Exposure of anaerobically growing cells to low concentrations of hydrogen peroxide also inactivated these three enzymes and led to rapid degradation of glycerol dehydrogenase. Glycerol dehydrogenase was purified and characterized after in vivo oxidative modification initiated by hydrogen peroxide. No differences in molecular weight, amino acid composition, or Km were detected between the native and oxidatively modified forms, although the modified enzyme had only 10% of the catalytic activity of the native form. The oxidatively modified enzyme was very susceptible to degradation by subtilisin while the native enzyme was resistant. Chloramphenicol prevented the inactivation and degradation of glycerol dehydrogenase caused by exposure to oxygen but did not block that caused by hydrogen peroxide. Thus, protein synthesis appears necessary for in vivo oxidative modification caused by exposure to oxygen but is not necessary when the process is initiated by exposure to hydrogen peroxide. The newly synthesized protein(s) presumably catalyzes the production of hydrogen peroxide which is required for the metal-catalyzed oxidative modification of susceptible enzymes.

Aerobiosis↗
PubMed1990

Histoautoradiographic study of rRNA and mRNA transcription activity related to secretory function in lizard epididymis.

The lizard epididymis is an androgen-dependent organ whose epithelial cells undergo marked changes in structure and secretory activity during the annual cycle. These changes are connected to fluctuations of testosterone levels. During the breeding season, the epididymis produces a major protein secretion, the L-proteins. In the present work we studied the fluctuations of RNA synthesis and accumulation during the annual cycle by means of histoautoradiographic methods. Total RNA synthesis was determined by uridine incorporation; accumulation of rRNAs and L-protein mRNAs were determined by in situ hybridization. Total RNA synthesis began during reorganization (Phase I), then increased gradually during differentiation and growth (Phase II). The synthesis peaked during maturation (Phase III), but stopped abruptly during hypersecretory activity (Phase IV). The rRNAs were very abundant from Phase II to Phase IV, which is related to the presence of many ribosomes as revealed by electron microscopy. The mRNAs of L-proteins were detected only during Phases III and IV in all epithelial cells. For every phase of the sexual cycle there exists a strong correspondence between the changes in transcriptional activity (rRNA and specific mRNA) of the epithelial cells and changes in the testosterone levels.

Animals↗
PubMed1990

[Long-term clinical course after second laparotomy in ovarian cancer].

A series of thirty consecutive epithelial ovarian cancer patients were reviewed after long-term follow-up (more than 5 y) since their second-look operation (SLO). All patients had advanced tumors (stages IIb-IV). Primary chemotherapy consisted of a cisplatin-associated regimen. For all patients adjuvant treatment had been planned after completion of the SLO. Mean follow-up after SLO was 68 months (47-103 months). Tumor status at SLO divided the patients in 2 subgroups: Group A = 13 patients (43%), with no evidence of histologically proved disease at time of operation (NED); Group B = 17 patients (57%), with macroscopic persistence of tumor. Survival was significantly better in the first group than in the second (77% at 5 yr vs less than 25%). Recurrence rate in the NED group was 7.7% (1 recurrence at 32 months). Eight of 17 patients with gross tumor at SLO underwent satisfactory resection. However, recurrence rate was high (75%) and survival rate was low (25% at 5 yrs). This result was not significantly better than that of patients with no optimal resection at SLO (9 patients, survival 22%). Second effort resection at SLO does not seem to be beneficial in these patients after partial failure of initial chemotherapy with cisplatin. The usefulness of systematic second look operations is discussed. Controlled randomized trials should be made to determine the exact role of SLO in ovarian cancer treatment.

Adult↗
PubMed1989

Randomized controlled trial of adenine arabinoside 5'-monophosphate in chronic active hepatitis B: comparison of the efficacy in heterosexual and homosexual patients.

Twenty-two heterosexuals and 21 homosexuals with chronic active hepatitis B and who had HBsAg, HBeAg and hepatitis B virus DNA in serum were randomized separately to receive adenine arabinoside monophosphate or placebo. In the 10 heterosexuals and nine homosexuals who received placebo, no change in hepatitis B virus DNA level and HBeAg was observed. Among the patients who received adenine arabinoside monophosphate, seven of the 12 heterosexuals and five of the 12 homosexuals lost hepatitis B virus DNA; five heterosexuals and three homosexuals also lost HBeAg; one homosexual lost HBsAg. There was no significant differences in response between heterosexual and homosexual patients. When results were pooled, there was a significant effect of adenine arabinoside monophosphate on hepatitis B virus replication. None of the 19 patients who received placebo but 50% of the 24 patients who received adenine arabinoside monophosphate were negative for serum hepatitis B virus DNA at 10 months after treatment (p less than 0.001) and none of the 19 patients who received placebo and 33% of the 24 patients who received adenine arabinoside monophosphate were negative for HBeAg in serum (p less than 0.005). Retrospective analysis showed that disappearance of hepatitis B virus DNA after administration of adenine arabinoside monophosphate was more common (i) in patients with a low pretreatment hepatitis B virus DNA level than in patients with a high pretreatment hepatitis B virus DNA level (8/11 vs. 4/13, p less than 0.05); (ii) in patients with a high pretreatment ALT level than in patients with a low pretreatment ALT level (10/14 vs. 2/10, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Lectin activity and distribution of chicken lactose lectin I in the extracellular matrix of the chick developing kidney.

A lectin activity inhibitable by thiodigalactose, N-acetyllactosamine, lactulose, lactose and by an antibody raised against CLL I (chicken-lactose lectin I) has been investigated in the chick embryo developing kidney. At post-induction stages this activity was found in both mesonephros and metanephros. In immunofluorescence and immunoelectron microscopy, the extracellular distribution of CLL I was similar in the mesonephros and the metanephros. The lectin was never found intracellularly; cultured kidney cells did not express any endogenous lectin but were rich in lectin-receptor sites, which led to the hyphothesis that CLL I is not produced in situ but could be adsorbed on renal cells. Potential physiological roles for embryonic lectins are discussed.

Animals↗
PubMed1987

[Determination of chloramphenicol residues with reverse-phase high pressure liquid chromatography. Use in a pharmacokinetic study in rainbow trout with confirmation by mass spectrometry].

A simple and rapid high-performance liquid chromatography (HPLC) method for the determination of chloramphenicol (CAP) residues in trout muscle tissue is described. After an acetonitrile-sodium chloride extraction followed by washing with hexane and purification through a Sep-Pak C18 cartridge, analysis is performed by reversed-phase HPLC on Spherisorb ODS-II (5 microgram) using water-methanol (1:1) as the mobile phase. The detection limit of the method is 5 micrograms/kg. The mean recovery from spiked muscle samples at the 10-micrograms/kg level is 56 +/- 7.4%. CAP residues are confirmed by gas chromatography-mass spectrometry at concentrations as low as 1 micrograms/kg. Residues were detected in trout muscle after oral administration during 15 days. On the tenth day after treatment, an average of CAP of less than 5 micrograms/kg was measured. No residues were detected after the twentieth day.

Animals↗
PubMed1986

Comparison of the regulatory and catalytic subunits of cAMP dependent protein kinase from Dictyostelium discoideum and bovine heart using polyclonal antibodies.

The purified regulatory (R) and catalytic (C) subunits of cAMP dependent protein kinase (cAK) from the primitive eukaryote Dictyostelium discoideum have been compared with the homologous proteins from bovine heart by SDS-PAGE followed by Western blotting using polyclonal antibodies. No cross-reaction could be demonstrated by this technique although the slime mold subunits share several functional properties with their mammalian counterparts and are able to form functional hybrid holoenzymes.

Animals↗
PubMed1986

Evolution and testosterone content of the epididymis during the annual cycle of the lizard Lacerta vivipara.

The lizard epididymis provides a model for studying the control, by testosterone, of a secretory activity related to the physiology of spermatozoa. To evaluate seasonal changes and to establish chronological correlations between the structure of the epididymis and its testosterone content, lizards (Lacerta vivipara) were killed between March (emergence) and October (retreat). The epididymal tissue was examined histologically and assayed for testosterone content. Ten stages of development were defined, mainly on the basis of the epithelial structure and the morphological features of secretory activity. Degeneration of the epithelium after the breeding period and its subsequent renewal also were considered. Increased epithelial height and secretory activity coincided with a progressive rise of the testosterone level, and a severe atrophy followed a sudden reduction of blood testosterone. Reorganization of the epithelium takes place when testosterone is at its lowest level, and the hormonal dependency of this stage is questionable. This study confirms in vivo, during a sexual cycle, experimental evidence previously obtained concerning testosterone's control of the secretory activity of the lizard epididymis.

Animals↗
PubMed1985

[Utero-ovarian implantation. Experimental study and critical evaluation of its use in women].

The authors studied experimentally ovario-uterine implantation in rats, an operation first performed many years ago yielding very rare and debatable results. This procedure is ineffective in the treatment of sterility due to endometrial proliferation over the ovary, which closes off rapidly the endometrial cavity and separates it from the implanted ovary. Much uncertainty surrounds the majority of previously reported successes, the few resultant pregnancies from ovario-uterine implantation considered due to hazard and completely unreliable. This operation has no place in the treatment of sterility.

Animals↗
PubMed1984

Immunopathologic aspects of woodchuck hepatitis.

The natural history of infection with woodchuck hepatitis virus (WHV) has been studied in a colony of 38 Marmota monax. Besides serologic assessment for WHV markers, light-microscopic findings of 61 liver biopsies were correlated with the results of immunofluorescence analysis for nucleocapsid (WHcAg) and surface (WHsAg) antigens. Twenty-four chronic WHsAg carriers all featured signs of continuous viral replication. Two major immunomorphologic patterns were observed in their livers: 1) portal hepatitis in which WHcAg accumulated in the cytoplasm and WHsAg was associated with the hepatocyte membrane and 2) periportal hepatitis in which WHcAg shifted toward nuclear localization and WHsAg became mostly intracytoplasmic. Progression from portal to periportal hepatitis, observed in 7 woodchucks, appeared to be induced by a partial recovery of specific immune reactivity to WHV, insufficient, however, to interrupt WHV replication. Deposits of WHsAg and immunoglobulins were present in the kidney and spleen of animals with severe hepatitis.

Animals↗
PubMed1980

[Sertoli cells of the impubescent pig: a method for obtaining isolated cells].

Minced whole testes from immature pigs were treated with collagenase (0.4 mg/ml) then with trypsin (2.5 mg/ml). The resulting suspension of cells was divided into sterile bottles containing medium 199 supplemented with 5 p. 100 calf serum. Bottles were maintained at 32 degrees C. After about 24 hours medium was changed 3 times to eliminate free cells. Within 3 days preparations consisting of 81.5% Sertoli cells, 0.5% Leydig cells and 18% peritubular cells were obtained.

Aging↗
PubMed1978

[Demonstration of testosterone secretion by testicular tissue of hypophysectomized boar as affected by HCG in organ culture].

Boar Leydig cells undergo a strong atrophy from 1 to 3 months after hypophysectomy but can be reactivated by the gonadotropin HCG in organ culture conditions. This reactivation which appeared at histological and ultrastructural level was evidenced by the capacity of testicular tissue to synthesize testosterone as judged by radioimmunoassay. Both synthesis in the tissue and release into the medium increased according the incubation time with HCG; the adjonction of 17 alpha-OH-pregneolone to culture medium led to increase the intra and extra-tissular concentration of testosterone.

17-alpha-Hydroxypregnenolone↗
PubMed1975

[Mitochondrial reorganization after HCG stimulation of Leydig cells from hypophysectomized hogs].

One to three months after hypophysectomy, porcine Leydig cells contain numerous dense bodies surrounded by a single membrane and crowded with dense rods geometrically arranged. In organotypic culture with HCG they undergo a striking evolution which leads first to intermediate bodies looking like peroxysomes and then to mitochondrial structures. This evolution is quantitatively reduced in a medium without HCG.

Animals↗