Sterol

About: Sterol is a research topic. Over the lifetime, 8117 publications have been published within this topic receiving 309926 citations. The topic is also known as: sterols & sterol lipids.

The role of cholesterol in chronic blepharitis.

Abstract: Chronic blepharitis has been a difficult disease to define either microbiologically or biochemically. Sterols from meibomian secretions of normal subjects and patients were analyzed, and important differences were observed. Based on analyses of these secretions, two significantly different (P less than 0.001) types of normal subjects were found, those with and those without cholesterol esters [Norm(CP) and Norm(CA), respectively]. All patients' secretions contained cholesterol esters. Evidence was obtained which suggests that oxysterols may control the ester cholesterol accumulation. Furthermore, only when cholesterol esters were present did wax and sterol esters containing unsaturated fatty acids accumulate. Over 90% of these unsaturated fatty acids were normal (unbranched); the rest were iso-fatty acids. Preliminary results also suggest that the ester fatty alcohols are much more complex than previously reported; seven alcohols were common to all samples analyzed. Additionally, highly oxygenated alcohols were detected, especially in the meibomian keratoconjunctivitis (MKC) disease group. The MKC samples also contained an alcohol (mass, M/Z 378) not present in any of the other samples analyzed. Based on analysis of variance and linear-regression models, it was determined that the long-chain (C20-28) fatty acids were more important in determining disease signs. Furthermore, in the MKC group, the ratio of unsaturated C18 fatty acids to cholesterol in the wax and sterol esters was significantly different (P less than 0.05) from the Norm(CP) group. The authors discuss the fact that rabbit meibomian secretions are stable, despite containing a very high percentage of ester sterols, and relate this to their high percentage of branched-chain fatty acids and low percentage of unsaturated fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Nystatin-Resistant Mutants of Yeast: Alterations in Sterol Content

Abstract: Mutants of the genes nys1 and nys3 differ from sensitive strains (nys+) in their sterol content. Ultraviolet absorption spectra of the nonsaponifiable material extracted from cells of nys+ demonstrated the presence of ergosterol and 24(28)-dehydroergosterol. In nys1 mutants, the spectrum suggests the presence of a new sterol. The absorption spectrum of extracts from nys3 mutants indicates absence of both ergosterol and 24(28)-dehydroergosterol and presence of another new sterol. Conversion of nys+ and nys3 to petite results in loss of 24(28)-dehydroergosterol in the former and the new sterol in the latter, whereas the new sterol in nys1 is only reduced. The sterols in ethanol-grown cells of all genotypes are essentially the same as is found for growth on glucose. With the exception of nys3 grown on ethanol, the mutants do not appear to be at a disadvantage compared to wild type.

Effect of Dietary Inclusion of Lactobacillus acidophilus ATCC 43121 on Cholesterol Metabolism in Rats

Abstract: This study examined the effects of Lactobacillus acidophilus ATCC 43121 (LAB) on cholesterol metabolism in hypercholesterolemia-induced rats. Four treatment groups of rats (n = 9) were fed experimental diets: normal diet, normal diet+LAB (2 x 10(6) CFU/day), hypercholesterol diet (0.5% cholesterol, w/w), and hypercholesterol diet + LAB. Body weight, feed intake, and feed efficiency did not differ among the four groups. Supplementation with LAB reduced total serum cholesterol (25%) and VLDL + IDL + LDL cholesterol (42%) in hypercholesterol diet groups, although hepatic tissue cholesterol and lipid contents were not changed. In the normal diet group, cholesterol synthesis (HMG-CoA reductase expression), absorption (LDL receptor expression), and excretion via bile acids (cholesterol 7 alpha-hydroxylase expression) were increased by supplementation with LAB, and increased cholesterol absorption and decreased excretion were found in the hypercholesterol diet group. Total fecal acid sterols excretion was increased by supplementation with LAB. With proportional changes in both normal and hypercholesterol diet groups, primary bile acids (cholic and chenodeoxycholic acids) were reduced, and secondary bile acids (deoxycholic and lithocholic acids) were increased. Fecal neutral sterol excretion was not changed by LAB. In this experiment, the increase in insoluble bile acid (lithocholic acid) reduced blood cholesterol level in rats fed hypercholesterol diets supplemented with LAB. Thus, in the rat, L. acidophilus ATCC 43121 is more likely to affect deconjugation and dehydroxylation during cholesterol metabolism than the assimilation of cholesterol into cell membranes.