Biomedical subjects

C Lutton

Publications and source records attributed to C Lutton.

54 records · Page 3Linked to original sources

PubMed1976

A new rat liver phospholipid exchange protein.

The soluble fraction from several mammalian tissue homogenates is known to stimulate phospholipid exchange between cell membrane fractions or artificial vesicles. All phospholipid exchange proteins purified to data exhibit an acidic isoelectric point. Using an assay that measures the transfer of [32P] phosphatidylcholine from liposomes to beef heart mitochondria, we report the presence of a new phospholipid exchange protein with a basic isoelectric point (8.4) in rat liver cytosol. A purification procedure, consisting of pH adjustment to 5.1, gel filtrations on Sephadex G 75 and DE 52 cellulose, isoelectric focusing between a pH of 5 and 10, and gel filtration on Sephadex G-50, yielded a fraction with high phosphatidylcholine exchange activity per mg of protein. This fraction exhibits a major band and two minor bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight of the major band (18 700) is close to that for basic exchange protein fraction obtained by gel filtration (17 000). The distribution of basic and acidic exchange proteins differs markedly in various tissues and animal species. About 50 and 35% of phosphatidylcholine exchange activity from rat liver and rat intestine respectively are due to basic phospholipid exchange proteins. In contrast, no basic exchange protein was found in beef heart and only a small amount in beef liver. In the latter organ, less than 10% of phosphatidylcholine exchange activity was due to a basic phospholipid exchange protein fraction.

Animals↗

PubMed1976

Elongation of (omega-14C)oleic acid and (omega-14C)nervonic acid.

During feeding experiments with [omega-14C]oleic acid and [omega-14c]nervonic acid to adult rats, 14C-labelled C26, C28 and C30 fatty acids were recovered from the intestinal mucosa, liver, plasma, kidney and stools. The structures of these fatty acids were determined by g.l.c., radio-g.l.c. and mass spectrometry. The Schmidt and Ginger degradation methods indicated that most of the 14C found in these extra-long fatty acids remained in the omega position. These radioactive extra-long fatty acids were found mainly in the polar lipids of rats killed 3 or 15 h after being fed on labelled oleic acid or nervonic acid. Rats killed 63 h later yielded only traces of these extra-long fatty acids. When the rats were given antibiotics or received the same radioactive fatty acids by intravenous injection, the labelled extra-long fatty acids could not be detected in any of the tissues. We conclude that they were probably synthesized by elongation of oleic acid and nervonic acid by intestinal micro-organisms (probably yeasts) and then absorbed by the intestinal mucosa.

Animals↗

PubMed1976

Phospholipid exchange proteins in rat intestine.

The 105,000 g supernatant and pH 5.1 supernatant fractions from rat intestinal homogenates stimulate phosphatidylcholine exchange between [32P] phosphatidylcholine liposomes and beef heart mitochondria. This active fraction shows the characteristics of a protein. Isoelectric focusing of the intestinal pH 5.1 fraction shows two peaks of phosphatidylcholine exchange activity: one at an acidic pH (4.5-5.3), the other in a basic pH range (8-9). The second peak of activity appears to be a new phospholipid exchange protein. The anatomic distribution of phosphatidylcholine exchange activity in intestine has been investigated. Expressed per mg of protein, phosphatidylcholine exchange activity is higher in mucosa than in the intestinal wall. No significant differences have been found between villi and crypts cells or between jejunal and ileal villi. Futhermore, exchange activity per mg of protein in mucosa is unaffected by fasting or by feeding a high fat or high cholesterol diet. This suggests that phospholipid exchange activity in the absorptive cells is not a rate limiting step in the process of fat absorption.

Animals↗

PubMed1976

The role of the digestive tract in cholesterol metabolism.

New studies have permit to reevaluate the importance of the digestive tract in each of the mechanisms regulating cholesterol turnover. Particularly, the role of the digestive trace in the rat cholesterol synthesis was underestimated. Is there a similar situation in man?

Animals↗

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

[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↗

PubMed1973