scispace - formally typeset
Search or ask a question
Topic

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.


Papers
More filters
Journal ArticleDOI
TL;DR: The results of this study show that the beta-CD-enhanced desorption of cholesterol (and other sterols) from monolayer membranes is influenced by the polarity of the desorbing molecules, as well as by lipid/lipid interactions in the membranes.
Abstract: In this study, we have examined a number of parameters which affect the rate of sterol desorption from a model membrane surface (a monolayer at the air/water interface) to cyclodextrins (CD) in the aqueous subphase. The desorption experiments were carried out at a constant lateral surface pressure with a zero-order trough, which allowed for a determination of desorption rates which were unaffected by monolayer substrate concentration. At a surface pressure of 20 mN/m (30 degrees C), 0.9 mM beta-CD caused a desorption of about 13 pmol of cholesterol per minute and square centimeter of monolayer area. The desorption of cholesterol proceeded linearly as a time function and was sensitive to the concentration of beta-CD in the subphase. The rate of cholesterol desorption increased as the monolayer surface pressure increased (3->35 mN/m) but decreased slightly with increasing temperature (15->30 degrees C). The rate of sterol desorption appeared to be influenced by the relative polarity of the sterols. Oxidized sterols desorbed significantly faster than cholesterol (e.g., 4-cholesten-3-one desorbed 8.4-fold faster than cholesterol), whereas less polar sterols desorbed at slower rates [e.g., 20(R)-isoheptyl-5-pregnen-3 beta-ol, a cholesterol analogue with a ten-carbon branched side chain, desorbed at 1/10 of the rate of cholesterol]. Cholesterol desorption from a monolayer membrane containing both cholesterol and a phospholipid was much slower than from a pure cholesterol monolayer. When the effect of dipalmitoylphosphatidylcholine and N-palmitoylsphingomyelin on cholesterol desorption rate was compared, it was found that cholesterol desorption was much more retarded from sphingomyelin monolayers as compared to that from phosphatidylcholine monolayers. Taken together, the results of this study show that the beta-CD-enhanced desorption of cholesterol (and other sterols) from monolayer membranes is influenced by the polarity of the desorbing molecules, as well as by lipid/lipid interactions in the membranes. Since beta-CD has no surface activity of its own, it appears to be a useful, nonintrusive catalyzer of cholesterol desorption and is expected to become a valuable probe in membrane and cell research.

197 citations

Journal ArticleDOI
TL;DR: In uninhibited plasma, efflux and net transport rates had similar kinetics, suggesting that these were linked functions and that net transport was initiated by a carrier-dependent efflux step that was associated with an equivalent influx of free sterol to the cells.
Abstract: Immunoaffinity chromatography has been used to study the determinants of sterol efflux and net transport from cultured fibroblasts to human plasma medium. Sterol efflux was highly (approximately 80%) dependent upon a minor lipoprotein fraction containing apolipoprotein A-I unassociated with other apolipoproteins. The remaining activity was associated with the lipoprotein-free fraction of plasma and could be replaced by apoprotein-free albumin. Efflux was independent of lecithin:cholesterol acyltransferase (EC 2.3.1.43) activity. Net transport (i.e., the excess of efflux over influx) was completely inhibited by inhibition of lecithin:cholesterol acyltransferase or its removal by affinity chromatography on immobilized antibodies to apolipoprotein A-I or D (components of the transfer complex in human plasma). In uninhibited plasma, efflux and net transport rates had similar kinetics, suggesting that these were linked functions and that net transport was initiated by a carrier-dependent efflux step that, in the absence of lecithin:cholesterol acyltransferase activity, was associated with an equivalent influx of free sterol to the cells and that, in the presence of lecithin:cholesterol acyltransferase, was associated with esterification and transfer protein activity. The cholesterol carrier lipoprotein function (approximately 5% of plasma apolipoprotein A-I) appears to be the first step of lecithin:cholesterol acyltransferase-linked sterol transport from cells.

196 citations

Journal ArticleDOI
TL;DR: Partial replacement of normal dietary fat consumption by sitostanol ester margarine appears to be an effective and safe hypocholesterolemic treatment in children with FH.

196 citations

Journal ArticleDOI
TL;DR: In this paper, a study was undertaken to determine if cholesterol sulfate, a substrate of this enzyme, accumulates in the pathological scale of these patients, which may underly the pathogenesis of the scaling in this disorder.
Abstract: Activity of the microsomal enzyme, steroid sulfatase, is absent in keratinocytes, fibroblasts, and leukocytes of patients with recessive x-linked ichthyosis. This study was undertaken to determine if cholesterol sulfate, a substrate of this enzyme, accumulates in the pathological scale of these patients. Scales from 8 patients with recessive x-linked ichthyosis, 10 patients with other forms of ichthyosis, and normal human outer stratum corneum were extracted with chloroform/water (1:2:0.8 by vol) and lipids were fractionated by quantitative, sequential thin-layer chromatography. Cholesterol sulfate was identified by cochromatography in several solvent systems, by its staining characteristics, by biochemical analysis, and by mass spectrometry. The mean cholesterol sulfate content of recessive x-linked ichthyotic scale was 12.5 +/- 0.8% of the total lipid, a fivefold increase over normal (P less than 0.0025), whereas the cholesterol sulfate content of other ichthyotic scale was normal. This increase in cholesterol sulfate content was accompanied by a decrease in total neutral lipids (P less than 0.0025) and free sterols (P less than 0.025) but no change in sterol esters or total sterols. These results demonstrate that deficiency of steroid sulfatase in recessive x-linked ichthyosis results in excessive accumulation of a substrate, cholesterol sulfate, in the pathologic scale, which may underly the pathogenesis of the scaling in this disorder. Measurement of cholesterol sulfate content in scale provides an alternative method to enzymatic assay for the diagnosis of this form of ichthyosis.

196 citations

Journal ArticleDOI
TL;DR: Subcellular fractionation of mutant Niemann‐Pick C fibroblasts accumulating LDL‐cholesterol showed excess unesterified sterol to be localized in the light lysosome‐light membrane region of a Percoll gradient, and revealed that cholesterol storage was associated with a specific alteration in the normal profiles of lysOSomal marker enzymes.
Abstract: Incubation of mutant Niemann-Pick C fibroblasts with low-density lipoprotein (LDL) resulted in excessive internalization of lipoprotein and extensive cellular over-accumulation of unesterified cholesterol. The uptake of LDL by the mutant cells appeared to occur through the classic LDL receptor pathway and internalized lipoprotein was processed in lysosomes. Lipoprotein uptake into mutant cells was associated with delays in the initiation of established cellular cholesterol homeostatic responses. Subcellular fractionation of mutant Niemann-Pick C fibroblasts accumulating LDL-cholesterol showed excess unesterified sterol to be localized in the light lysosome-light membrane region of a Percoll gradient, and revealed that cholesterol storage was associated with a specific alteration in the normal profiles of lysosomal marker enzymes.

195 citations


Network Information
Related Topics (5)
Fatty acid
74.5K papers, 2.2M citations
90% related
Amino acid
124.9K papers, 4M citations
86% related
Enzyme
32.8K papers, 1.1M citations
85% related
Polyunsaturated fatty acid
35.4K papers, 1.2M citations
85% related
Cholesterol
44.6K papers, 1.9M citations
84% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023104
2022250
2021131
2020154
2019151
2018117