cholesterol-alpha-oxide and Arteriosclerosis

Oxysterols, being oxygenated derivatives of cholesterol, are as many kinds as one hundred. They are found in the foodstuffs, the blood and arterial tissues of animals with hypercholesterolemia, the human atheroma, the foam cell from atherosclerotic tissues, as well as in the oxidized low density lipoprotein. The results of experiments have demonstrated that oxysterols are cytotoxic and they are injurious to a variety of cells including vascular endothelial cells, smooth muscle cells and monocyte/macrophages, suggesting that oxysterols could play a key role in the initiation and pathogenesis of atherosclerosis.

Topics: Animals; Arteriosclerosis; Carrier Proteins; Cholesterol; Humans; Lipoproteins, LDL; Receptors, Steroid

Increasing the energy value of diets with dietary fat, particularly fats rich in saturated fatty acids, can result in the elevation of plasma total and lipoprotein cholesterol. In the present study, experimental diets were designed to examine the effects of increasing the energy content of diets with a saturated fat source and cholesterol in a non-purified diet on hyperlipoproteinaemia and aortic plaque composition in the atherosclerosis-susceptible Japanese quail (Coturnix japonica) model of human atherosclerosis. Commercial poultry diets containing two levels (i.e. 60 or 120 g/kg) of beef tallow as the primary source of saturated fat were balanced for endogenous cholesterol or supplemented with cholesterol (i.e. 0.5 or 5.0 g/kg) and fed to quail for 9 weeks to examine the effects on whole plasma, lipoprotein and aortic plaque lipid composition in relation to aortic plaque formation. Hypercholesterolaemia (P < 0.001) was confirmed in birds fed on high-cholesterol (HC) diets only. An interaction (P = 0.05) between dietary cholesterol and fat intake level was observed for plasma triacylglycerols (TG) and was specific to changes observed in VLDL composition. Diet-induced changes in lipoprotein total cholesterol, TG and phospholipid composition were greatest in the portomicron and VLDL fractions in birds fed on atherogenic diets. Hyperlipoproteinaemia induced by the 60 g/kg added beef tallow-HC diet resulted in significant (P < 0.001) aortic plaque deposition, which was further enhanced in birds fed on the 120 g/kg beef tallow-HC diet. Quail fed on 120 g/kg beef tallow-HC diets exhibited the most severe aortic plaque formation, with marked increases in aortic tissue cholesterol content and quantifiable amounts of several cholesterol oxides (5,6 alpha-epoxy-5 alpha-cholesterol, 7 beta-hydroxycholesterol, cholestanetriol, 7-ketocholesterol and 25-hydroxycholesterol). In summary, hyperlipoproteinaemia associated with HC diets with a greater proportion of energy from saturated fat produced a combined effect in altering plasma and lipoprotein lipid composition as well as aortic tissue cholesterol and cholesterol oxide content in the Japanese quail.

Topics: Analysis of Variance; Animals; Aorta; Arteriosclerosis; Bird Diseases; Cholestanols; Cholesterol; Cholesterol, Dietary; Coturnix; Dietary Fats; Disease Models, Animal; Energy Intake; Hydroxycholesterols; Hypolipidemic Agents; Ketocholesterols; Lipids; Lipoproteins; Male; Regression Analysis

Two populations of immigrants to London and to the West Indies from the Indian subcontinent have higher than expected morbidity and mortality from atherosclerosis but do not show the commonly accepted major risk factors. This study investigated the hypothesis that ghee, a clarified butter product prized in Indian cooking, contains cholesterol oxides and could therefore be an important source of dietary exposure to cholesterol oxides and an explanation for the high atherosclerosis risk. Substantial amounts of cholesterol oxides were found in ghee (12.3% of sterols), but not in fresh butter, by thin-layer and high-performance-liquid chromatography. Dietary exposure to cholesterol oxides from ghee may offer a logical explanation for the high frequency of atherosclerotic complications in these Indian populations.

Topics: Arteriosclerosis; Butter; Cholesterol; Chromatography, High Pressure Liquid; Diet, Atherogenic; Dietary Fats; Emigration and Immigration; Humans; India; London; Oxides; Risk; Trinidad and Tobago

Previous findings indicating that the oxidation products of cholesterol are associated with atherogenicity have led to a comparative study of the subchronic effects of feeding rabbits purified cholesterol, oxidized cholesterols free of cholesterol and cholesterol esters, or a mixture of cholesterol and oxidized cholesterols. Macroscopically, the cholesterol-fed animals exhibited 6-fold more arterial lesions than the animals fed cholesterol-free oxidized cholesterols. Microscopically, there was no statistically significant difference from the control in the number of histochemically-defined lesions in any of the groups. However, the lesions in the cholesterol-fed group were more severe, as indicated by a statistically significant increase in the magnitude of the lesions. This increased severity was also characterized by greater frequency and intensity of Azure A/Thionin, VonKossa, and Horseradish Peroxidase-Wheat Germ Agglutinin staining. Electron-microscopic studies of normal appearing arterial tissues showed an increased density of viable smooth muscle cells and an increase in vacuolar extracellular debris in the cholesterol-fed group. Oxidized cholesterols in the concentrations and relative compositions administered here are markedly less atherogenic to rabbits than highly purified cholesterol.

Topics: Animals; Aorta; Arteries; Arteriosclerosis; Cholesterol; Cholesterol, Dietary; Chromatography, High Pressure Liquid; Diet, Atherogenic; Female; Microscopy, Electron; Muscle, Smooth, Vascular; Oxidation-Reduction; Rabbits