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Biomedical subjects

M Chevalier

Publications and source records attributed to M Chevalier.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1980

[Plasma testosterone level and structure of the epididymis and accessory organs of the boar (Sus scrofa L.) after hypophysectomy followed by hCG gonadotropin administration].

Hypophysectomy of the boar resulted in a rapid drop in plasma testosterone level. hCG injections (400 IU/day) considerably elevated testosteronemia (up to 16.41 ng/ml). This effect was obtained either in the days following the operation or several months after (up to 134 days). In the latter case, the effect was temporary because the testosterone level dropped again after 15 days of injections. The sexual target organs (epididymis, seminal vesicle, prostate and Cowper glands) underwent structural change which, in the epithelium, corresponded to fluctuations in testosterone level. These effects were less marked in the cauda epididymis than in other target tissues. In various target organs, the conjunctivomuscular stroma developed after the operation; it did not regress at all, or incompletely, when the epithelia were stimulated indirectly by hCG, and began to hypertrophy when the hCG was no longer effective. Variations in stromal reaction were organ-dependent. When the hCG was administered for more than 14 days, it seemed to have a desensitizing effect; these mechanisms have been discussed.

Animals↗
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↗