Showing papers on "Sterol published in 1982"
TL;DR: The studies suggest that the effects of SCP2 are related to delivery of cholesterol from preformed stores to and into mitochondria for initiation of steroid hormone synthesis, and may represent an important modulator of sterol metabolism in adrenal cortical cells.
219 citations
TL;DR: The present paper shows that on a capillary column this separation is successful, so that cholesterol metabolism can be quantitated accurately without preceding TLC separation.
149 citations
TL;DR: The presence in human plasma of MVA, an obligate precursor of cholesterol, in amounts apparent related to the rate of cholesterol synthesis offers a noninvasive, nonisotopic method for studying cholesterol synthesis in man.
Abstract: We tested the hypothesis that the rate of cholesterol synthesis in tissues determines the concentrations of mevalonic acid (MVA) in plasma. We found that plasma MVA concentrations were correlated (i) with increased rates of whole-body cholesterol synthesis (measured by sterol-balance methods) in patients treated with cholestryamine resin (ii) with decreased rates of whole-body sterol synthesis (indicated by conversion of labeled acetate to sterol in freshly isolated mononuclear leukocytes) in out-patients after 4 weeks on a cholesterol-rich diet. In addition, a diurnal rhythm of plasma MVA concentrations was observed in patients whose activities were strictly controlled on a metabolic ward. At the peak of the rhythm (between midnight and 3 a.m.) MVA concentrations were 3-5 times greater than at the nadir (between 9 a.m. and noon). Furthermore, a relationship between the diurnal rhythm of plasma MVA and endogenous cholesterol synthesis is suggested by our finding that the plasma MVA rhythm was suppressed by cholesterol feeding (1,200 mg/day) and abolished by a 12-day fast. The presence in human plasma of MVA, an obligate precursor of cholesterol, in amounts apparent related to the rate of cholesterol synthesis offers a noninvasive, nonisotopic method for studying cholesterol synthesis in man.
142 citations
TL;DR: The rapid and marked diurnal fluctuation of squalene and free methyl sterols in plasma lipoproteins suggests that these precursors are metabolized on and off lipoprotein levels, inferring that circadian rhythm also regulates human cholesterol production.
130 citations
TL;DR: The manner in which cells retain their sterol content is reviewed and the findings appear to be broadly applicable to conditions in vivo.
128 citations
TL;DR: Scatchard analysis of the binding of amphotericin B to sterols in egg phosphatidylcholine/sterol vesicles revealed that amphoteric in B was bound to ergosterol by approximately one order of magnitude more tightly than to cholesterol.
105 citations
TL;DR: The vertical flux and free steroid alcohol (sterol) and ketone composition of particulate material was determined using sediment traps deployed at 389, 988, 3755 and 5068 m at a station in the equatorial North Atlantic, PARFLUX E. as discussed by the authors.
97 citations
TL;DR: Evidence is presented for multiple functions of sterols in Saccharomyces cerevisiae, which could provide the required sterol in quantities capable of sustaining growth through an entire culture cycle.
92 citations
TL;DR: Rat liver microsomes were incubated with various sterols suspended in Triton WR-1339, and the extent of esterification of these sterols by acyl CoA:cholesterol acyltransferase was determined, indicating that the structure of the alkyl side chain plays an important role in the interaction between substrate and enzyme.
89 citations
TL;DR: It is concluded that luteinized human granulosa cells use LDL-carried sterol as the primary substrate for steroidogenesis, and the effects of LDL on steroidogenesis were dose dependent and saturable.
Abstract: Human granulosa cells cultured in the presence of estradiol, FSH, and LH secreted relatively little progesterone during the first 3–5 days of culture. The cells then underwent a morphological transformation associated with a 10-fold or more increase in progestin production. Cells not cultured with the tropic hormones usually produced progestin at a lower rate. Serum was required for the expression of maximal steroidogenic activity. Inhibitors of de novo sterol synthesis, ML-236B and 5-cholesten-3β,25-diol, did not affect progestin secretion by luteinized cells cultured in 20% serum, but these inhibitors did reduce [14C]acetate incorporation into sterols by 90%. ML-236B also did not affect hCG-stimulated progesterone secretion by the cells.However, when the cells were changed into lipoprotein-deficient medium, progestin production was markedly reduced within 24 h. The addition of low density lipoproteins (LDL) to the culture fluid restored progestin production, whereas high density lipoproteins tended to f...
85 citations
TL;DR: It is suggested that they may be produced de novo by a route involving nor-isoprenoid pyrophosphates and nor-squalene as intermediates, rather than as bacterial degradation products of brassicasterol (or related sterols) as previously suggested in the literature.
Abstract: The major 4α-monomethyl sterol of the dinoflagellateGymnodinium simplex was identified as (24S)-4α,24- dimethylcholestan-3β-ol. The major 4-demethyl sterols were characterized as (24R)-24-methylcholesta-5,22-dien-3β-ol (brassicasterol) and 27-nor-(24R)-24-methylcholesta-5,22-dien-3β-ol. The latter sterol has the opposite configuration at C-24 to that assigned to occelasterol, which has the same basic structure and has previously been reported as a constituent of the sterols of a marine worm. 24-Nor-cholesta-5,22-dien-3β-ol was also identified along with several other trace sterols. The co-occurrence of 27-nor-(24R)-cholesta-5,22-dien-3β-ol together with 24-nor-cholesta-5,22-dien-3β-ol and brassicasterol provides new evidence for the biosynthetic origins of the two former nor-sterols. It is suggested that they may be produced de novo by a route involving nor-isoprenoid pyrophosphates and nor-squalene as intermediates, rather than as bacterial degradation products of brassicasterol (or related sterols) as previously suggested in the literature.
Patent•
17 May 1982
TL;DR: Synthetic sapogenin and sterol compounds, administered orally to warm-blooded animals, inhibit the absorption of cholesterol and are useful in the treatment of hypercholesterolemia.
Abstract: Synthetic sapogenin and sterol compounds, administered orally to warm-blooded animals, inhibit the absorption of cholesterol and are useful in the treatment of hypercholesterolemia. Particular compounds suitable for such purposes include glycosides with spirostane, spirostene, or cholesterol aglycones, and esters of spirostanes, spirostenes and cholesterol.
TL;DR: Quantitative differences were found in the chemical composition of royal jelly samples collected in spring and summer by the same producer, the main difference was in the free fatty acids, which showed a marked increase in 10-hydroxydecanoic acid in summer.
Abstract: SummaryQuantitative differences were found in the chemical composition of royal jelly samples collected in spring and summer by the same producer. The main difference was in the free fatty acids, which showed a marked increase in 10-hydroxydecanoic acid in summer. The sterol and hydrocarbon fractions were also investigated. The most significant sterols were identified by gas chromatography—mass spectrometry. The hydrocarbon components, identified by their retention times, were a homologous series of straight-chain compounds, from C16 to C33, with even and odd numbers of carbon atoms. Considerable amounts of some hydrocarbons were found. Of the sterols identified, the most abundant was 24-methylene cholesterol; stigmasterol, β-sitosterol, Δ5-avenasterol, Δ7-avenasterol and cholesterol were also present.
TL;DR: The previously demonstrated mutagenicity of naturally air-aged (autoxidized) USP cholesterol in test strains of Salmonella typhimurium has been confirmed, and themutagenic species from mutagenic cholesterol preparations were shown to be neutral steroids that are very much more polar than the cholesterol autoxidation products so far identified.
TL;DR: Findings support the contention that inhibition of sterol C-14 demethylation in U. maydis is the primary mode of toxicity of fenarimol, etaconazole, and miconazole.
TL;DR: In experimental conditions the inhibition of DNA synthesis was not related to the suppression of the HMG CoA reductase activity, and the specificity of the structures required for DNA synthesis inhibition could be explained by the involvement of a specific hydroxysterol binding protein.
TL;DR: The results indicate that hormonal modulation contributes to the regulation of cytosolic HMG-CoA reductase activity.
TL;DR: Uterine fluid cholesterol affinity, therefore, correlated with sperm capacitation activity in utero, and Serum albumin has been identified as a uterine sterol acceptor.
Abstract: Cholesterol from rabbit sperm cells was bound by uterine fluid proteins following intrauterine insemination into ovulating does. Serum albumin has been identified as a uterine sterol acceptor. Progesterone administration suppressed binding and elevated the concentration of cholesterol, phospholipid, and protein. Uterine fluid cholesterol affinity, therefore, correlated with sperm capacitation activity in utero.
TL;DR: Six species of phytoplankton,Pseudoisochrysis paradoxa, Isochrysis galbana, MonochRYsis lutheri, Platymonas suecica, Thalassiosira fluviatilis and aChaetoceros species, were cultured in the laboratory and their sterol contents analyzed utilizing digitonin precipitation, thin layer and gas chromatography and gas Chromatography-mass spectrometry.
Abstract: Six species of phytoplankton,Pseudoisochrysis paradoxa, Isochrysis galbana, Monochrysis lutheri, Platymonas suecica, Thalassiosira fluviatilis and aChaetoceros species, were cultured in the laboratory and their sterol contents analyzed utilizing digitonin precipitation, thin layer and gas chromatography and gas chromatography-mass spectrometry. A total of 7 sterols were found in phytoplankton. The occurrence of these sterols, cholest-5-en-3β-ol, cholest-5,22-dien-3β-ol, 24-methylcholesta-5,24(28)-dien-3β-ol, 24-methylcholest-5-en-3β-ol, 24-methylcholesta-5,22-dien-3β-ol, 24-ethylcholest-5-en-3β-ol and 24-ethylcholest-5,22-dien-3β-ol, differed significantly among the various phytoplankton species. Cultures ofP. paradoxa biosynthesized both of the sterols found in this species when incubated in the presence of14C- or3H-mevalonic acid for 0.5–9 days. These sterols were cholesterol and 24-methylcholesta-5,22-dien-3β-ol. Since 5 of the sterols found in the phytoplankton commonly occur in mollusks which feed on phytoplankton, it is likely that at least some of the tissue sterols in mollusks are of dietary origin.
TL;DR: The data suggest that free sterols can be transferred from the bile to the gallbladder mucosa, and that altered hepatic cholesterol synthesis is associated with the development of the cholesterolosis of human gallbladders.
TL;DR: The influence of cholesterol on ADP-ATP exchange activity was measured in the reconstituted system, submitochondrial (sonic) particles and mitoplasts and in the natural environment of the carrier protein, i.e., the inner mitochondrial membrane.
TL;DR: Comparative sterol metabolism studies show that the yellow fever mosquito,Aedes aegypti, was shown to be capable of dealkylating and converting a radiolabeled C29 dietary sterol ([14C] sitosterol) to cholesterol.
Abstract: The honey bee,Apis mellifera, does not convert C28 and C29 phytosterols to cholesterol as found in most previous studies of phytophagous or omnivorous insects, but instead the workers and queens selectively transfer 24-methylenecholesterol, sitosterol and isofucosterol from their endogenous sterol pools to the brood larvae regardless of the sterol in the worker diet. Administering radiolabeled sterols by feeding and injection has made it possible to trace this selective transfer through a second generation of the honey bee. In further comparative sterol metabolism studies, the yellow fever mosquito,Aedes aegypti, was shown to be capable of dealkylating and converting a radiolabeled C29 dietary sterol ([14C] sitosterol) to cholesterol. Metabolic studies with several radiolabeled dietary sterols and an inhibitor of steroid metabolism in the yellow fever mosquito further verified this capability.
TL;DR: It is suggested that phosphatidylethanolamine exerts marked influence on serum lipoprotein levels and Ethanolamine, but not choline and inositol, showed an effect on serum Lipoproteins similar to egg yolk phospholipid.
Abstract: To evaluate alterations of serum lipoproteins, liver lipids and fecal sterol excretion caused by feeding a crude soybean phospholipid preparation, the effect of purified phospholipids and phospholipid bases were studied in rats. Soybean phosphatidylcholine preparations showed no effect on serum lipoproteins and liver lipids. Egg yolk phospholipid, which contained phosphatidylethanolamine and phosphatidylcholine, caused a decrease in serum cholesterol and apoprotein A-I and an increase in serum apoprotein B and liver cholesterol. Ethanolamine, but not choline and inositol, showed an effect on serum lipoproteins similar to egg yolk phospholipid. All phospholipids tested increased fecal excretion of neutral sterols. It is suggested that phosphatidylethanolamine exerts marked influence on serum lipoprotein levels.
TL;DR: As part of ongoing studies of the medicinal aspects of Maritime flora, particularly the herbal remedies of the Micmac and Malecite Indians, the sterols and triterpenes of Achillea millefolium L. (Compositae), a widely used herbal remedy, were determined using modern techniques.
TL;DR: The kinetics of cholesterol labeling was studied in the plasma lipoproteins of three subjects who had received an oral dose of octadeuterated cholesterol and an intravenous administration of 3H-cholesterol and 14C-mevalonate or 13C-acetate and the rates of the various processes involved in cholesterol turnover were calculated.
TL;DR: A novel metabolic role for apo E is suggested in the promotion of sterol transport uncoupled to LCAT-activity in plasma of subjects homozygous for deficiency of lecithin:cholesterol acyltransferase.
Abstract: In the plasma of 4 subjects homozygous for deficiency of lecithin:cholesterol acyltransferase, the level of many apolipoproteins (apo A-I, apo A-II, apo B, apo D) was greatly decreased relative to normal, while that of apo E is increased 5-fold. The lipoprotein complex containing lecithin:cholesterol acyltransferase with apo A-I and apo D in normal plasma is completely absent. The major part of apo E is unassociated with other apolipoproteins. The apoprotein-dependence of sterol efflux and net transport from human skin fibroblasts into plasma was determined by immunoaffinity chromatography. In normal plasma the major component of efflux of sterol radioactivity from labeled fibroblasts was dependent upon unassociated apo A-I. In LCAT-deficient plasma, apoprotein-dependent efflux was largely a function of unassociated apo E. When fibroblasts were incubated with fibrinogen-free unfractionated LCAT-deficient plasma, there was no spontaneous net transport of sterol either into or from the cells, indicating that efflux and influx rates were in balance. When apo E was removed by affinity chromatography, there was net transport from plasma to cells. These findings suggest a novel metabolic role for apo E in the promotion of sterol transport uncoupled to LCAT-activity.
TL;DR: The major sterol of rabbit meibomian secretion was shown to be 24, 25-dihydro-Δ8-lanosterol both by gas-liquid chromatography on three different stationary phases and by mass spectrometry.
TL;DR: The complex sterol mixture isolated from A, nigra was found to contain a low level of Δ 4 -3-keto steroids, 5β-stanols and 4α-methyl sterols in addition to regular (4-demethyl) sterols.
TL;DR: Total sterol and phospholipid biosynthetic rates showed parallel reductions in cultures acclimating to a shift from 37 to 15 degrees C growth conditions, indicating an increase in the conversion rate of sterols to sterol esters at the lower temperature.
TL;DR: It has been shown that inter-species variation in the susceptibility of C14 demethylases and ability of the antifungals to penetrate the fungal cell, as well as structural variation, affect the antIFungal activity of this class of compounds.
Abstract: Several factors influencing the activity of imidazole-containing antifungals as inhibitors of sterol C14 demethylation have been investigated in Candida spp. It has been shown that inter-species variation in the susceptibility of C14 demethylases and ability of the antifungals to penetrate the fungal cell, as well as structural variation, affect the antifungal activity of this class of compounds.