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Biomedical subjects

F Chevallier

Publications and source records attributed to F Chevallier.

At least 37 records · Page 2Linked to original sources
PubMed1976

In vivo study of free and esterified cholesterol turnover in various tissues of the rat.

Rats were infused for 3.5 to 10 hrs with either red cells or plasma previously labelled in vivo by [3H]-cholesterol. Cholesterol specific radioactivities were measured in plasma, HDL, LDL and VLDL, and various tissues. Red cell infusions led to a higher labelling of free than of esterified cholesterol in the plasma of infused rats. The opposite situation was observed following plasma infusion. Comparison of free and esterified cholesterol specific radioactivities in each tissue showed that esterified cholesterol was transferred from plasma to all the tissues, except the adrenals. Study of the ratios of cholesterol specific radioactivities from one experimental group to the other in each tissue, made it possible to demonstrate clearly the occurence of hydrolysis within all the studied tissues except 5 of them where its existence remains uncertain (lung, heart, kidney, tendon, muscle) and of esterification in 3 tissues (adrenal, liver lung). In addition, ratios of cholesterol radioactivities (free/ester) were found to be identical in plasma and in 4 tissues, where neither hydrolysis nor esterification were detected (heart, muscle, kidney, tendon). This finding is an argument in favor of a simultaneous transport of free and esterified cholesterol from plasma into these 4 tissues and suggests that the entire lipoprotein particles can penetrate these tissues, with no specificity of one special class. In adrenal, unlike all other tissues: 1) the turnover of esterified cholesterol was achieved mostly by hydrolysis and esterification in situ; 2) a preferential lipoprotein class (LDL) was responsible for the transport of free cholesterol from the plasma.

Adrenal Glands↗
PubMed1976

[Absorption cooefficient for dietary cholesterol, the fundamental parameter of cholesterol dynamic equilibrium in rats].

By an isotopic equilibrium method turnover rates of rats cholesterol have been determined in 30 various experimental conditions. A deductive analysis of these overall old data discovers that absorption coefficient of dietary cholesterol is a determinative parameter of cholesterol dynamic equilibrium. Synthesis which takes places chiefly in the intestine, fecal external secretion and fecal excretion of cholesterol are linearly increasing when the absorption coefficient is decreasing. Two types of exception have been noted. The most interesting concerns the case where there is a supplementary synthesis. For pregnant of lactating female rats placenta or mammary glands are directly interested. For rats with ligated bile duct or feed with cholestryramine, liver must be incriminated. These two last cases are the alone on 30 where hepatic synthesis play very probably a notable role in the dynamic equilibrium of cholesterol.

Absorption↗
PubMed1975

Effect upon brain weight and cholesterol content of maintaining rats of various ages at constant weight.

Rats weighing 400 g were maintained at constant weight for 500 days. Their diet consisted of 14 g/day for the first 150 days and 13 g/day thereafter. A second group of rats weighing 350 g was fed 11.5 g/day for 400 days; at the end of the experiment, these rats weighed 382 g. Under these conditions, the increase in brain weight and in quantity and concentration of cholesterol in the brain as a function of time was identical to that observed in the control rats fed ad libitum. Rats weighting 250 g fed 8.5 g/day for 200 days showed a body weight increase of 16 g. Up to the age of 115 days, the evolution of brain weight in terms of time did not differ from that observed in control rats. Rats weighting 100 g and fed 4.5 g/day showed an increase of 28 g after 300 days. The increase in brain weight and in brain cholesterol content as a function of time was less than that observed in the control rats. A curve deduced from these results has the practical interest of indicating the daily energy requirement for maintaining rats at a chosen constant weight. Expressed in terms of body surface area, the daily energy intake appears constant. It was also observed that, when conditions of minimal economy are imposed upon the adult rat, brain nutrition is not modified. But for young rats (100 g),brain development under these nutrtional conditions is affected.

Age Factors↗
PubMed1975

[Influence of the daily ingestion of a total unsaponifiable extract from avocado and soy bean oils on cholesterol metabolism in the rat].

The effects of ingestion of an unsaponifiable avocado and soya extract (P.I.A.S.) on the rates of cholesterol turnover were studied in the Rat smaller than in toto greater than. The balance is the same as in control rats, but fecal and urinary excretions of cholesterol are well enhanced and transformation into bile acids is consequently reduced. The absorption coefficient of cholesterol is unchanged in spite of the presence of phytosterols in the extract. The extract having been said to have a beneficial effect on scleroderma a special study was undertaken of the skin. The GLC analysis of sterols show the very probable presence of phytosterols and a richer proportion of cholesterol, precursors particularly methostenol in the skin of rats fed on P.I.A.S. than in that of the controls. These modifications do not produce any variations in the rate of cholesterol synthesis as measured in vitro.

Acetates↗