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At least 19 recordsLinked to original sources
PubMed1979

Dependence of the effects of dietary cholesterol and experimental conditions on serum lipids in man. I. Effects of dietary cholesterol in a linoleic acid-rich diet.

In this experiment the effect of dietary cholesterol in a linoleic acid-rich diet on serum cholesterol was tested. In a cross-over design 41 young healthy students received a linoleic acid-rich diet for 4 weeks at two levels of dietary cholesterol. The diet contained 14 to 15 energy% linoleic acid. The high cholesterol diet was obtained by adding two egg yolks a day to the rations. Supplementation of the linoleic acid-rich diet with the egg yolk cholesterol caused a significant rise of serum cholesterol of about 11 mg/100 ml (0.29 mmole/liter). The dietary cholesterol did not influence serum triglyceride levels. The influence on serum cholesterol was much less than expected, based on several predictive formulas. It is concluded that the presence of a high content of linoleic acid in the diet reduces the effect of dietary cholesterol on serum cholesterol if the cholesterol is provided as egg yolk.

Adult↗
PubMed1979

Changes in cholesterol metabolism with dietary cholesterol in children with familial hypercholesterolaemia.

1. Possible defects in cholesterol metabolism were sought in children with familial hypercholesterolaemia. 2. In nine affected children (eight heterozygotes and one homozygote) and in five healthy children, cholesterol synthesis and bile acid synthesis were determined from the excretion of steroids in the faeces during a low cholesterol diet. Cholesterol synthesis of 10.1 +/- 4.4 mg day-1 kg-1 in the hypercholesterolaemic children was similar to that in these and other normal children. Mean bile acid synthesis of 4.0 +/- 2.1 mg day-1 kg-1 also resembled normal values though three severely affected heterozygotes excreted substantially less. 3. The response to 4 weeks' additional 450 mg of dietary cholesterol/day led to variable changes in the plasma cholesterol and in the sterol balance. On average the affected children showed a rise in plasma cholesterol which resembled that in healthy subjects. The sterol balance fell in most, suggesting a reduction in cholesterol synthesis, which is the normal response to dietary cholesterol. 4. The response to dietary cholesterol was therefore at least qualitatively similar in the hypercholesterolaemic children to that reported in healthy subjects.

Adolescent↗
PubMed1979

Evidence for the operation of the extrahepatic lipoprotein receptor system in vivo in rats. Effect of dietary cholesterol and orotic acid, alone or in combination, on the rate of synthesis of cholesterol and fatty acid in various tissues, measured by using 3H2O.

1. The biosynthesis of cholesterol in vivo was studied at a number of tissue sites in rats by using 3H2O as precursor. Overall, the mass of cholesterol synthesized was in good agreement with the rate of cholesterogenesis, as determined by kinetic analysis of cholesterol specific-radioactivity-time curves after administration of radiolabelled cholesterol. 2. Dietary cholesterol increased the circulating concentration of cholesterol and inhibited endogenous cholesterogenesis, with concomitant increases in the concentration of esterified cholesterol, in all tissues studied. Addition of ororic acid to the cholesterol-supplemented diet tended to reverse each of these changes in extrahepatic tissues. 3. The co-ordinated change in cholesterol biosynthesis and esterification, with no change in total cholesterol content, in extrahepatic tissues, is attributed to control by receptor-mediated lipoprotein uptake. 4. Further reduction of the concentration of the apoprotein B-containing lipoproteins by addition of orotic acid to a diet without supplementary cholesterol did not further enhance cholesterogenesis. We consider that the relatively high rates of extrahepatic cholesterogenesis in normolipidaemic rats are attributable to the low concentration of low-density lipoprotein.

Animals↗
PubMed1979

Serum alpha-lipoprotein responses to variations in dietary cholesterol, protein and carbohydrate in different non-human primate species.

Serum alpha-lipoprotein responses to variations in dietary cholesterol, protein, and carbohydrate were studied in different nonhuman primate species. Chimpanzee, rhesus, green, patas, squirrel and spider monkeys all showed significant interspecies differences in serum total cholesterol responses to 1.84 mg/kcal exogenous cholesterol. Dietary cholesterol significantly increased the alpha-lipoprotein cholesterol in all species except rhesus and chimpanzee. Among these species, there was no relationship between the basal serum lipoprotein profile and subsequent lipoprotein responses to dietary cholesterol. Although the level of dietary protein at 6%, 12%, and 37% of calories had no appreciable main effect on serum total cholesterol in spider monkeys, very low protein diet (6% of calories) produced a significant elevation in alpha-lipoprotein cholesterol. Serum alpha-lipoprotein responses to exogenous cholesterol (1.84 mg/kcal) was highest for the very low protein diet and lowest for low protein diet (12% of calories). Diets with high sucrose (76.5% of calories) and low saturated fat (12.5% of calories) containing no added cholesterol were tested in squirrel and spider monkeys and produced a consistent serum total cholesterol response; the alpha-lipoprotein response was significantly higher in squirrel monkeys than in spider monkeys. The above findings have implications in experimentally induced and comparative atherogenesis.

Animals↗
PubMed1979

Cholesterol metabolism in the liver and intestine of the chick: effect of dietary cholesterol, taurocholic acid and cholestyramine.

The effect of feeding cholesterol, taurocholic acid, or cholestyramine to chicks on cholesterogenesis from [1-14C] acetate in liver and intestine was determined in vitro using tissue slices, and in vivo by i.v. injection of [14C] acetate. The conversion of cholesterol to bile acids in liver in vivo was measured in the same treatments after i.v. injection of [3H] cholesterol. Hepatic cholesterogenesis in vitro and in vivo was depressed by dietary cholesterol and taurocholate and enhanced by cholestyramine. Intestinal cholesterogenesis in vivo was depressed only by taurocholate whereas ileal cholesterogenesis in vitro was reduced by dietary cholesterol. Conversion of cholesterol to bile acids was enhanced by dietary cholesterol and cholestyramine and depressed by taurocholate. Hepatic cholesterol metabolism in the chick appears to be regulated by mechanisms similar to those reported for other species.

Acetates↗
PubMed1979

Effect of enhancement of cholesterol degradation during neonatal life of guinea pig on its subsequent response to dietary cholesterol.

The effect of feeding cholestyramine to neonatal guinea pigs on their subsequent plasma cholesterol levels and response to dietary cholesterol were studied. Male neonatal guinea pigs were suckled for 6 days. One group was maintained on a 1.1% cholestyramine diet for 6 weeks and the control group weaned normally. Both groups of guinea pigs were then fed a standard diet of Guinea Pig Chow for 6 weeks. During the standard diet period bile acid and neutral sterol excretion rates were significantly higher in the group previously treated with cholestyramine than the control group despite the similarity in plasma cholesterol levels. When both groups of guinea pigs were subjected to a 0.5% cholesterol diet for 4 weeks, plasma cholesterol levels were significantly lower in the group previously treated with cholestyramine than the control group. The plasma cholesterol levels continued to be significantly lower in the group previously treated with cholestyramine after an additional four weeks on standard diet. These results suggest that stimulation of cholesterol catabolism in the neonatal period can influence the subsequent response to dietary cholesterol.

Animals↗
PubMed1976

Phylogenetic variability of serum lipids and lipoproteins in non-human primates fed diets with different contents of dietary cholesterol.

The response of serum lipids and lipoproteins to different levels of dietary cholesterol (0.05% to 1.5% w/w) was measured in six nonhuman primate species. Relative response of serum cholesterol in different species, measured in terms of response, index, varied with dietary cholesterol concentration. The overall response for the different diets allowed ranking of the species as follows: Squirrel is greater than green is greater then spider is approximately thesus is approximately patas is greater than chimpanzee The serum cholesterol response was reflected not only in an increase in beta + pre-beta-lipoprotein cholesterol but also in alpha-lipoprotein cholesterol, with significant differences among species in the amount of cholesterol transported in the lipoprotein classes.

Animals↗
PubMed1977

Effect of dietary cholesterol on the pattern of osmium deposition in the symbiote-containing cells of the pea aphid.

Pea aphids left for 48 h in unbuffered osmium tetroxide show heavy staining of many organelles in the symbiote-containing cells (mycetocytes and sheath), embryos and oenocytes very similar to that characteristic of mammalian sterol-synthesizing cells. However, the staining of the per-aphid cells is, to a large extent, dependent on the presence of cholesterol benzoate, or free cholesterol, in the aphid's diet. In aphids cultured in vitro with 3H mevalonate in the presence of added cholesterol, the incorporation of label into the cholesterol and lanosterol fractions is significantly reduced. If the dietary cholesterol effects a similar inhibition in vivo, the cholesterol-dependent osmium staining could be due to precursors(s) of cholesterol accumulating in the intracellular sites described. There is also osmium staining of large (normally electron-transparent) vacuoles in mycetocytes, gut and fat body, irrespective of dietary cholesterol.

Animals↗
PubMed1979

Dietary cholesterol is co-carcinogenic for human colon cancer.

Colorectal carcinoma is becoming the most common form of visceral cancer in Western populations. A fat-related dietary factor is implicated in its pathogenesis, and evidence in man suggests that this factor may be cholesterol. Dietary cholesterol is co-carcinogenic in animals with colon cancer, and there is indirect evidence for a similar role in man. It is proposed that prolonged exposure to dietary cholesterol is co-carcinogenic for human colon cancer in that it facilitates the development, growth, and spread of this disease.

Animals↗
PubMed1978

Estrogen enhances dietary cholesterol induction of saturated bile in the hamster.

The influence of ethinyl estradiol (EE) on the effects of dietary cholesterol on the biliary saturation index and on the rate-limiting hepatic enzymes of cholesterol synthesis, hydroxymethylglutaryl-CoA-reductase, and bile acid synthesis, 7 alpha-hydroxylase, were determined. Four groups of 12 male hamsters were treated for 1 month with EE, 15 micrograms per kg per day, or placebo vehicle administered intraperitoneally and fed either a standard diet, 0.8 mg of cholesterol per g of food, or high cholesterol diet, 2.4 mg of cholesterol per g. The high cholesterol diet increased the saturation index to 1.00 +/- 0.03 (P less than 0.01) from 0.65 +/- 0.02 in untreated hamsters on the standard diet. EE treatment on the high cholesterol diet further increased (P less than 0.01) the saturation index to 1.15 +/- 0.02. The high cholesterol diet decreased (P less than 0.01) hydroxymethylglutaryl-CoA-reductase activity from 308 +/- 16 pmoles per mg per min in untreated hamsters on the standard diet. The addition of EE treatment had no effect on hydroxymethylglutaryl-CoA-reductase activity. The high cholesterol diet increased (P less than 0.01) 7 alpha-hydroxylase activity from 23 +/- 1.0 pmoles per mg per min in untreated hamsters on the standard diet. The addition of EE decreased (P less than 0.01) 7 alpha-hydroxylase activity from that in untreated hamsters on the standard diet. The conclusions are as follows: (1) EE prevented dietary cholesterol-induced stimulation of cholesterol 7 alpha-hydroxylase activity; (2) EE enhanced the ability of dietary cholesterol to induce saturated bile; and (3) gallstone formation in estrogen-treated women may result from impaired metabolism of dietary cholesterol.

Animals↗