Showing papers on "Sterol published in 1969"
TL;DR: Estimates of daily synthesis of cholesterol in man are estimated by measuring the excretion of cholesterol and its conversion products during periods of controlled sterol intake (sterol balance method), using isotopic or chromatographic procedures (or a combination of the two).
302 citations
TL;DR: The hypocholesterolemic effect of polyunsaturated fat was associated with total fecal sterol excretion twice greater than the amount of cholesterol calculated to leave the plasma, which suggested possible loss of cholesterol from the tissues as well.
Abstract: Six normal men were fed formula diets containing either highly saturated fat (cocoa butter, iodine value 32) or polyunsaturated fat (corn oil, iodine value 125). The sterol balance technique was used to compare the changes in serum cholesterol concentration with the excretion of fecal steroids. The method used for the analysis of fecal steroids was chemical, with a final identification and quantification by gas-liquid chromatography. It was confirmed that the chemical method for fecal steroid analysis was accurate and reproducible. The three dietary periods were each 3 wk in length. In sequence, cocoa butter (period I), corn oil, and cocoa butter (period III) were fed at 40% of the total calories. All diets were cholesterol free, contained similar amounts of plant sterols, and were identical in other nutrients. Corn oil had a hypocholesterolemic effect. Mean serum cholesterol concentrations were 222 mg/100 ml (cocoa butter, period I), 177 during corn oil, and 225 after the return to cocoa butter. Individual fecal steroids were determined from stools pooled for 7 days. Both neutral steroids and bile acids were altered significantly by dietary polyunsaturated fat. The change in bile acid excretion was considerably greater than the change in neutral steroids. Corn oil caused a greater fecal excretion of both deoxycholic and lithocholic acids. The total mean excretion (milligrams per day) of fecal steroids was 709 for cocoa butter (period I), 915 for corn oil, and 629 for the second cocoa butter period. The enhanced total fecal steroid excretion by the polyunsaturated fat of corn oil created a negative cholesterol balance vis-a-vis the saturated fat of cocoa butter. The hypocholesterolemic effect of polyunsaturated fat was associated with total fecal sterol excretion twice greater than the amount of cholesterol calculated to leave the plasma. This finding suggested possible loss of cholesterol from the tissues as well.
259 citations
TL;DR: Isolation of tritium-labeled sterols from plasma and red blood cells of normal male subjects showed some absorption had occurred, but it was much less than for comparable doses of labeled cholesterol, and high specific activity values were observed in bile sterols, suggesting that β-sitosterol is selectively excreted by this route.
Abstract: Tritium labeled β-sitosterol was administered orally to 5 normal humans and to 5 terminal patients. Isolation of tritium-labeled sterols from plasma and red blood cells of normal male subjects showed some absorption had occurred, but it was much less than for comparable doses of labeled cholesterol. The highest level observed after a single 50-mg. dose of β-sitosterol was about 0.015 mg. per 100 ml. of blood in the total sterol fraction. These values are uncorrected for dilution by any unlabeled β-sitosterol present in the diet and are therefore minimum values. The disappearance rate from blood was slightly higher than for labeled cholesterol. Larger doses of tritium labeled β-sitosterol administered to a series of terminal patients gave similar results for blood levels and disappearance rates. Isolation of sterols from a variety of tissues showed β-sitosterol to be widely distributed. High specific activity values were observed in bile sterols, suggesting that β-sitosterol is selectively excreted by this route. Aorta and other blood vessels had lower amounts of tritium labeled sterols than most other tissues. The total amount of β-sitosterol present in blood and principal visceral organs (excluding intestine) was estimated in one patient as about 0.5 per cent of a single dose of 258 mg. given 5 days previously. Although the distribution pattern of absorbed β-sitosterol was similar to that of fed labeled cholesterol, it did not become esterified to as great an extent.
139 citations
TL;DR: Cholesterol isolated chromatographically from liver processed as outlined above has been identified unequivocally by mass spectrometry and a remarkable quality of fine-structural preservation is obtained.
Abstract: A major methodological problem in the intracellular localization of cholesterol is the nearly complete extraction of sterols during routine dehydration and embedding procedures for electron microscopy. Cholesterol digitonide (a sterol complex with digitonin), however, is qualitatively insoluble in these solvents. Mouse liver has been prepared as follows: (a) Flickinger's aldehyde fixative, 20 hr; (b) Flickinger's fixative containing 0.2% digitonin, 24 hr; (c) cacodylate wash, 24 hr; (d) 1% OsO(4), 2 hr; (e) acetone dehydration; and (f) Epon 812 infiltration under vacuum, 28 hr. After the last step, an analysis of the tissue for sterol content under optimal analytical conditions demonstrates a retention of 99% of the unesterified cholesterol present in unfixed mouse liver. Liver prepared in an identical manner except for omission of digitonin is essentially devoid of sterols. Cholesterol isolated chromatographically from liver processed as outlined above has been identified unequivocally by mass spectrometry. Liver from step (f) also has been polymerized, thin-sectioned, and examined in the electron microscope. A remarkable quality of fine-structural preservation is obtained. The major alteration encountered is the presence of small cylindrical "spicules," often occurring as tightly packed concentric lamellae, at membrane surfaces.
116 citations
TL;DR: The data demonstrate that glyceryl ether diesters and alkyl-acyl cholinecontaining lipids tend to accumulate in hepatoma 7777 which is a relatively fastgrowing tumor, and indicates that essential fatty acids are poorly utilized by hepatomas.
92 citations
TL;DR: Selective cleavage of the side chains of various sterols at C-17, giving rise to androsta-1,4-diene-3,17-dione (ADD), occurred in the presence of α,α′-dipyridyl by microorganisms of the following genera.
Abstract: Cholesterol decomposing ability of 1589 microbial strains was examined. Two hundreds and thirty six strains from actinomycetes, bacteria, molds, and yeasts were found capable of oxidizing cholesterol into cholestenone. Cholesta-1,4-dien-3-one was produced by 5 strains of Streptomyces. The complete decomposition of cholesterol molecule was observed in the genera: Arthrobacter, Bacillus, Brevibacterium, Corynebacterium, Microbacterium, Mycobacterium, Nocardia, Protaminobacter, Serratia, and Streptomyces. α,α′-Dipyridyl and arsenite inhibited decomposing enzymes giving rise to cholestenone, cholesta-1,4-dien-3-one, and an intermediate probably devoid of the sterol side chain.Selective cleavage of the side chains of various sterols at C-17, giving rise to androsta-1,4-diene-3,17-dione (ADD), occurred in the presence of α,α′-dipyridyl by microorganisms of the following genera: Arthrobacter, Bacillus, Brevibacterium, Corynebacterium, Microbacterium, Mycobacterium, Nocardia, Protaminobacter, Serratia, and Strept...
82 citations
Journal Article•
78 citations
TL;DR: No detectable amount of sterol was found in three species of the Peronosporales and the sterols produced by a number of Phycomycetes have been studied by several gas chromatographic techniques and in some cases by mass spectroscopy.
73 citations
TL;DR: The structure of the 7,22-bisdehydrocholesterol, a previously unknown compound, was established on the basis of ultraviolet, infrared, nuclear magnetic resonance, and mass spectral data for both the free sterol and its acetate derivative, and also by chemical conversions of the acetate to known compounds.
69 citations
TL;DR: A fraction of solvolyzable sterol conjugates with the chromatographic properties of steryl sulphates was isolated from pooled faeces collected from infants 1–4 and 6–12 months old, showing higher concentrations of cholesteryl and 24-hydroxy-cholesteryl sulphates from the older than from the younger subjects.
Abstract: A fraction of solvolyzable sterol conjugates with the chromatographic properties of steryl sulphates was isolated from pooled faeces collected from infants 1–4 and 6–12 months old. The major sterols in this fraction were analyzed by gas chromatography-mass spectrometry. The pool from the younger infants was shown to contain cholesterol and 22α-, 24χ-, and 26-hydroxycholesterol and the pool from the older infants contained cholesterol, campesterol, β-sitosterol, and 22α-, and 24χ-hydroxycholesterol. The concentrations of cholesteryl and 24-hydroxy-cholesteryl sulphates were higher in faeces from the older than from the younger subjects.
59 citations
TL;DR: Ergosterol was the only sterol detected in Crithidia fasciculata cultured in serum-free medium and when grown in the presence of serum the cells also contained cholesterol and 22,23-dihydroergosterol (or its C24 isomer).
TL;DR: Total lipid from adult male and adult paired Schistosoma mansoni has been fractionated by thin-layer chromatography and a remarkably small amount of sterol ester was found in adult flukes considering the prevalence of this compound in mouse blood.
Abstract: Total lipid from adult male and adult paired Schistosoma mansoni has been fractionated by thin-layer chromatography. Phospholipid, free sterol, and triglyceride were major components of both mixtures. A remarkably small amount of sterol ester was found in adult flukes considering the prevalence of this compound in mouse blood. Free fatty acids were found to be a minor component. Cholesterol was the major free sterol present.The technical assistance of Mrs Katye Ross Summerlin is gratefully acknowledged.
TL;DR: The incorporation of the label of this compound into liver cholesterol by intact rats has been demonstrated and the presence of a sterol with the expected properties of 5α-cholest-8(14)-en-3β-ol in rat skin has been demonstrating.
TL;DR: The mechanism for specificity in sterol absorption must be located early in the transport of the sterols within the intestinal mucosa cell, according to the ratio of sterols in the fed sterol mixture.
01 Jan 1969
TL;DR: Danielsson as mentioned in this paper showed that 7α-hydroxylation is the initial step on the pathway of degradation of cholesterol to bile acids, and that this proposed reaction might be the rate limiting reaction.
Abstract: From a quantitative standpoint the breakdown of cholesterol to bile acids is very important and from the studies of Lindstedt (1) it was argued that one of the possible early metabolites on this pathway was cholest-5-en-3β, 7α-diol (7α-hydroxycholesterol) As far as can be established bile acid formation occurs exclusively in the liver and the enzymic hydroxylation of cholesterol to 7α-hydroxy-cholesterol is a function of the endoplasmic reticulum or the microsomal fraction of rat liver Since few sterol metabolites other than bile acids have oxygenated functions at C7 it follows that if 7α-hydroxylation is the initial step on the pathway of degradation of cholesterol to bile acids, then this proposed reaction might be the rate limiting reaction Thus the introduction of the 7α-hydroxyl group into the ubiquitous cholesterol molecule would result in the conversion of cholesterol to 7α-hydroxycholesterol, a metabolite on an exclusive pathway to bile acids Such branchpoints in metabolism are possible targets for regulation mechanisms The conversion of cholesterol to bile acids has been reviewed by Danielsson (2)
TL;DR: Myelination was retarded by treatment with AY‐9944 and 20, 25‐diazasterol, possibly by the limited amount of sterols available, and the metabolism of the abnormal myelin constituents in drug‐treated animals is discussed in relation to the molecular structure of the myelin membrane.
Abstract: — Three drugs known to inhibit biosynthesis of cholesterol, Clofibrate, 20, 25-diazacholesterol and AY-9944 were administered by stomach intubation to suckling rats. At weaning the rats were killed and subcellular fractions, including myelin, were prepared from the brains and spinal cords and analysed for sterol content. Central nervous tissue fractions from Clofibrate-treated rats showed some decrease in total sterols, but the sterol species were qualitatively normal. AY-9944 given to rats caused high amounts of 7-dehydro-cholesterol to accumulate in all brain and spinal cord fractions with the highest amounts (32–38 percent of total sterols) in myelin. In diazasterol-treated rats desmosterol reached 48 per cent of the sterols of myelin. A group of rats was allowed to survive after the final drug intake (21 days) and their brain and spinal cord sterol content followed up to 60 days. At 30 days the proportion of dehydrocholesterol or desmosterol comprised over half the total myelin sterol. By 60 days of age the 7-dehydrocholesterol had almost completely disappeared from all fractions while substantial amounts of desmosterol were retained in myelin. Myelination was retarded by treatment with AY-9944 and 20, 25-diazasterol, possibly by the limited amount of sterols available. The metabolism of the abnormal myelin constituents in drug-treated animals is discussed in relation to the molecular structure of the myelin membrane.
TL;DR: A sterol, probably β-sitosterol, is consistently found in animal tissues in minute amount, and in most organs, except liver, plasma, adrenals, the percentage of esterification was 3–10 times greater for precursor sterols than for cholesterol.
TL;DR: In the absence of a mutualistic fungus, X. ferrugineus (F.) (Coleoptera: Scolytidae) pupated in the 2nd genoration on test diets which contained 0.2 g of ergosterol.
Abstract: In the absence of a mutualistic fungus, X. ferrugineus (F.) (Coleoptera: Scolytidae) pupated in the 2nd genoration on test diets which contained 0.2 g of ergosterol. Cholesterol at 0.2 g per diet batch was not an adequate source of sterol in the 2nd fungus-free generation. Those sterol requirements of the 1st fungus-free generation of the insect which were not in the diets apparently were met by carry-over of such nutrients from the previous generation (stock culture) fed fungus-containing diets.
TL;DR: Five species of Chlorella examined were found to contain ergosterol as their major sterol, and all five species were similar with respect to sterols, qualitatively and quantitatively.
TL;DR: In experiments with delipidized serum containing unesterified cholesterol, cellular sterol synthesis decreased as free cholesterol concentration in the medium increased, and in experiments using medium containing increasing lecithin concentration and no exogenous sterol, the concentration of leCithin markedly influenced the distribution of synthesized sterol between the cells and the medium which then directly influenced the amount of sterol synthesized.
Abstract: L cells were cultivated in test medium which contained 14C-sodium acetate, and the amount of labeled digitonin-precipitable sterol was assayed in medium and cells. Increasing concentrations of whole serum in the medium had two effects: depressed cellular synthesis and enhanced release of synthesized sterol from the cells. In experiments with delipidized serum containing unesterified cholesterol, cellular sterol synthesis decreased as free cholesterol concentration in the medium increased. In other experiments using medium containing increasing lecithin concentration and no exogenous sterol, the concentration of lecithin markedly influenced the distribution of synthesized sterol between the cells and the medium which then directly influenced the amount of sterol synthesized. These experiments indicate that cell sterol synthesis is regulated by internal levels of free sterol. This, in turn, is a function of cellular sterol flux which is regulated by the concentration and composition of serum lipoprotein in the medium.
TL;DR: Results indicate that whereas most of the cholesterol in the chick originated from the egg yolk, cholesterol biosynthesis was active in the brain and provided about 90% of its cholestero content.
TL;DR: Synthetic 22- trans -cholesta-5,22,24-trien-3β-ol supported normal growth and development and was converted to cholesterol by the tobacco hornworm.
TL;DR: In this paper, Bowen et al. used an artificial skin of hardened gelatine to examine the factors affecting penetration of skin by cercariae of the bird schistosome, Austrobilharzia terrigalensis.
Abstract: An artificial skin of hardened gelatine was used to examine the factors affecting penetration of skin by cercariae of the bird schistosome, Austrobilharzia terrigalensis.The percentage of cercariae able to penetrate through a gelatine membrane was increased by a factor of 3–4 by coating the membrane with a thin layer of lipid collected from the surface of chicken skin.The free sterol fraction, isolated from chicken skin surface lipid by thin-layer chromatography, stimulated penetration to the same extent as whole skin lipid.Cholesterol was detected in the sterol fraction by mass spectrometry and pure cholesterol had the full stimulating effect on cercarial penetration.Skin lipid, from which free sterols had been removed, lost the stimulatory effect on cercariae, but full activity was recovered by adding cholesterol to the sterol-free lipid. Fractions of skin lipid containing free fatty acids or triglycerides, wax esters and sterol esters similarly failed to stimulate penetration.These results establish that penetration of A. terrigalensis cercariae is greatly stimulated by the free sterols present in the surface lipid of chicken skin but cholesterol may not be the only active sterol. Cholestanol and the plant sterols campesterol and β-sitosterol were also detected in chicken skin surface lipid. These sterols were not tested for activity on cercariae because samples free from cholesterol could not be obtained.Some cercariae were able to penetrate plain gelatine membranes not coated with cholesterol but small amounts of free sterol were detected in the gelatine itself. This sterol could not be completely removed by prolonged solvent extraction and consequently it is not known whether any cercariae are able to penetrate in the complete absence of sterols.Temperature had a marked effect on penetration of cercariae; lowering the temperature from 40 to 25 °C reduced the number of successful penetrants by a factor of 4.I am grateful to Miss V. Bowen for excellent technical assistance and to Dr J. McLeod of the Research School of Chemistry, Australian National University, who performed and interpreted the mass spectrometry. This investigation was partly supported by a research grant from the World Health Organization.
TL;DR: The sulfates of cholesterol, campesterol and β-sitosterol have been identified in the sterol sulfate fraction from the meconium of the tobacco hornworm, Manduca sexta (Johannson).
TL;DR: The resolution on Sephadex LH-20 lipophylic gel of several C 27, C 24, C 21, and C 19 steroids of interest in studies of cholesterol autoxidation has been achieved.
TL;DR: The ergosterol ester fraction of Saccharomyces cerevisiae has been analyzed following a variety of incubation conditions and Esters of C16 and C18 fatty acids are the predominant ones, followed by those of C14 acids.
TL;DR: It is proposed that esterification of cholesterol accompanies keratinization and that a higher proportion of esterified sterols in surface lipids as opposed to epidermal lipids has been amply documented.
TL;DR: In this article, it was shown that the sterol of the slime mold Dictyostelium discoideum [Δ 22-stigmasten-3-β-ol (Xa)] contains five deuterium atoms, when extracted from D. discoidem fed on cells of a methionine-less strain of E. coli grown in presence of [Me-2H3] methionines.
Abstract: Previous work of several laboratories has shown that the two carbon atoms C-28 and C-29 of the ethyl or ethylidene side chains of phytosterols are introduced on a C-24 unsaturated side chain by two successive C-methylation steps. A scheme, based on previous work of Nes et al. and Goodwin et al., gives the various intermediates which can be formed by stabilisation of the intermediate carbonium ion (II). It was usually thought that ethylidene compounds such as (III) were the precursors of ethyl compounds such as (VIII) and this has been proved recently in the case of poriferasterol (IX) which contained four deuterium atoms when Ochromonas malhamensis was grown in presence of [Me-2H3] methionine [8].
In the present paper it is reported that the sterol of the slime mold Dictyostelium discoideum [Δ 22-stigmasten-3-β-ol (Xa)] contains five deuterium atoms, when extracted from D. discoideum fed on cells of a methionine-less strain of E. coli grown in presence of [Me-2H3] methionine. The unsaturated sterol (Xa) is accompanied by the saturated sterol (XIa) which was not previously found in this organism.
Mass spectrometry of the pentadeuterated sterols (Xa) and (XIa) seemed to show conclusively that all five deuterium atoms are located in the ethyl side chain [11], but it was thought necessary to confirm this conclusion by a detailed analysis of the side chain; thus, the sterol (Xa) was ozonised and part of the side chain isolated as a crystalline p-phenylphenacyl ester (XIIIa). Mass spectrometry of this compound and of a synthetic non-labelled (XIIIb) and the corresponding monodeuterated derivative (XIIIc) confirms that all five deuterium atoms of the Dictyostelium sterol (Xa) are in the ethyl side chain.
These results exclude an ethylidene compound (such as III) as a precursor of the sterol (Xa); they do not allow us to choose between other possible routes illustrated in the scheme. Our experiments also show that there is no hydrogen shift during the second methylation step.
TL;DR: The results presented support the hypothesis that the inhibition of lymphocyte protein synthesis by steroid hormones occurs only when the steroid is bound to a plasma protein.
TL;DR: It is inferred that esterification of cholesterol with linolenic or arachidonic acids would accelerate its removal from the normal or atherosclerotic arterial wall.