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Biomedical subjects

R Truhaut

Publications and source records attributed to R Truhaut.

At least 55 records · Page 3Linked to original sources
PubMed1979

[Vitamin A consumption in pregnant and non pregnant rats, and in castrated rats receiving or not receiving estradiol or pregnenolone; relation to tocopherol and cytochrome P-450].

Consumption of vitamin A and cytochrome P 450 by pregnant Rat is more important than in non pregnant and ovariectomised Rat. Estradiol implant in ovariectomised female has some, but slighter, influence only on retinol. These physiological situations have no action on the hepatic levels of tocopherols (total and alpha). These results are discussed.

Animals↗
PubMed1979

Accentuation of white phosphorus induced fatty liver by phenobarbitone in male rats compared to female rats.

The possible influence of a potent enzyme inducer, phenobarbitone, on white phosphorus fatty liver, was studied. Pretreatment by phenobarbitone for four days in white phosphorus poisoned rats provoked a decrease in mortality and an increase in hepatic triglycerides (fatty liver) in male rats. The activity of uridine diphosphoglucuronyl transferase (UDPGT), an inducible enzyme, is not modified by this pretreatment in white phosphorus poisoned rats. The accentuation of white phosphorus fatty liver by phenobarbitone in male rats could be explained by an increased hydroxylation of testosterone, thus counteracting the protective effect of this hormone on fatty liver.

Animals↗
PubMed1979

Fatty liver induced by high doses of rifampicin in the rat: possible relation with an inhibition of RNA polymerases in eukariotic cells.

The steatogenic effect on the liver of Rifampicin, a potent inhibitor of the DNA-dependent RNA polymerase in bacteria, was investigated in male and female rats which received either 200 mg or 400 mg of Rifampicin/kg/24 h for 8 days. The determination of total lipids (TL), triglycerides (TG), total cholesterol (TC) and phospholipids (PL) showed a significant increase of TL, TG and TC in the liver at a dose of 400 mg. There was better reproducibility in the male whose blood TG and PL were significantly decreased. These results showed that fatty liver can be induced by very high doses of Rifampicin in rats. A blockage of the very low density lipoproteins (VLDL) biosynthesis and/or secretion can be expected. As a potent steatogenic toxin, alpha-amanitin, is a strong inhibitor of RNA polymerase II in eukariotic cells, a relationship between the RNA polymerase inhibition induced by both of substances and a subsequent inhibition of the biosynthesis of the protein moiety of lipoproteins can be considered. Nevertheless Rifampicin is at present not considered as an inhibitor in eukariotic cells and it will be of great interest to test such a possibility with the high doses used in these experiments, in further work.

Animals↗
PubMed1979

An overview of the problem of thresholds for chemical carcinogens.

Toxicological evaluation in quantitative terms of substances that have been shown to be carcinogenic is very difficult, mainly because, for the great majority of environmental carcinogenic chemicals, the available data, both from experimental studies in animals and from epidemiological studies in humans, on dose-effect relationships, especially at low levels, are very limited. There is an urgent need for research in this area. At present, the most sensible approach is to try to determine no-effect levels by long-term investigation of the effects of low levels in animal species that are most similar to man in their metabolic potential and their sensitivity. Very low safety factors (2500 to 5000) should be applied to the values thus obtained, in order to be as far as possible on the safe side in establishing pragmatically acceptable limits. At present, since all chemical carcinogens pose a hazard, human exposure to them must be reduced to the feasible minimum.

Animals↗
PubMed1979

[Dismutation as a metabolic pathway : transformation of the trimethyl 3,5,5, cyclohexanone (author's transl)].

Besides novel routes of biotransformation of xenobiotic substances recently reported, such as N-glucuronidation of teritary amines and quaternary ammonium componds, N-glucosylation, N-carbamylglucuronide formation from a primary amine, C-glucuronidation, conjugation with long-chain fatty acids, with polypeptides, carbon-chain elongation, stereospecific inversion of configuration at a satured carbon atom, formation of methylthio metabolites, the authors have described a new metabolic pathway: dismutation, in the case of 3,5,5, - trimethylcyclohexanone (dihydroisophorone). As a matter of fact, this compound leads, in vivo, to the formation of isophorone alpha and of cis and trans 3,5,5, - trimethyl cyclohexanols. These compounds, extracted from the urine of treated rats and rabbits, have been identified by gas-liquid chromatography and thin-layer chromatography.

Animals↗
PubMed1979

[Influence of a tributyltin oxide oily aerosol on the exploratory behaviour toward the mouse (author's transl)].

Inhalation of an oily aerosol of bis (tributyltin oxide) (TBTO) after single or repeated expositions (1 hour) disturb the exploratory behaviour in the mouse. Weak concentrations (42 and 84 ppm) stimulate exploratory activity while large doses (170 and 340 ppm) significantly decrease it. Modification in brain amine levels may appear but the observed perturbance seems to be more dependent from oily vehicule than TBTO itself.

Aerosols↗
PubMed1978

[Effect of platinum derivatives on the inducible and repressible liver microsomal enzyme systems in the rat: inhibition of zoxazolamine-hydroxylase and induction of dimethyl-nitrosamine demethylase isoenzymes by cis-dichlorodiamine platinum (cis-PtCl2(NH3)2) and ammonium hexachloroplatinum (PtC16(NH4)2)].

Two platinum derivatives, cis-PtCl2(NH3)2 and PtCl6(NH4)2 have been studied for their effects on the Rat on cytochrome P450 in hepatic parenchyma on zoxazolamine-hydroxylase, a typical inducible system and on the two isoenzymes of dimethyl-nitrosamine demethylase, typical repressible systems. The inhibitory effect of PtCl6(NH4)2 on zoxazolamine-hydroxylase activity, previously shown by the authors, has been confirmed. The cis-PtCl2(NH3)2 also significantly inhibits zoxazolamine-hydroxylase activity. On the other hand, both of the platinum derivatives decrease cytochrome P450 level and enhance the dimethyl-nitrosamine metabolism. These various effects and their relationship are discussed.

Animals↗