Whole body and hepatic cholesterol synthesis rates in the guinea-pig: effect of dietary fat quality
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Digitonin
Abstract In the classic Schoenheimer—Sperry method for estimating cholesterol [J. Biol. Chem. 106, 745 (1934)] it is selectively precipitated with digitonin, and interference by other substances is minimized. The standards used in the color development are pure cholesterol. We suggest that the standard cholesterol should also be converted to cholesterol digitonide and treated identically to the test samples. When this is done, the values for cholesterol in test samples are significantly higher, both for free and total cholesterol in blood serum and for total cholesterol in tissues. Moreover, recovery experiments showed that error is diminished. Values for serum total cholesterol obtained when cholesterol digitonide standards were used were closer to those obtained by the method of Abell et al. than when pure cholesterol standards were used.
Digitonin
Blood cholesterol
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Plant sterols are natural dietary components whose lowering effect on serum cholesterol level has been well documented. The purpose of this study was to determine the effects of plant-sterol-supplemented processed rice on serum of cholesterol level. In the determination, a double-blind, placebo-controlled study was conducted using a 3-group parallel protocol. The subjects comprised 33 healthy Japanese males and females with a total cholesterol level of 234. 6± 24.6 (mean±SD, mg/ml). They were given a daily ration of rice balls prepared from plant-sterol-supplemented rice containing 1.46 and 2.25 g of plant sterol for 4 weeks. Serum total cholesterol was reduced by 4.6% in the 2.25 g/day plant-sterol (as β-sitosterol of about 968 mg/day) group (p<0.05). As for LDL cholesterol level, such reduction was observed in 4.3%. In all the groups, no significant change in the level of HDL-cholesterol, triacylglycerol, RLP-cholesterol, VLD-lipoprotein, LD-lipoprotein or other kinds of apolipoprtein and biochemical parameters. In addition, no remarkable abnormality was observed in the subjective and objective examination of what symptoms. These results indicate that plant-sterol-supplemented processed rice is useful in supporting healthy eating habits for reducing serum total cholesterol level.
Plant sterols
Serum cholesterol
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SUMMARY: Several steroids closely related structurally to cholesterol were tested for growth-promoting activity for a strain of Mycoplasma mycoides (V5) and a Mycoplasma sp. isolated from a goat (gy). Cholestanol and latho-sterol promoted growth of both strains. Cholestenone, cholest-5-en-3-one, 7-dehydrocholesterol and progesterone inhibited cholesterol-promoted growth; cholestanone was almost inactive either as growth promotor or as growth inhibitor. Cholesterol amounted to 4–5% of the dry weight of the water-washed organisms, or about 20% of the total lipids, of either strain grown in the presence of cholesterol. Cholesterol esters or transformations to other steroids were not detected in lipid extracts of the v5 strain grown in the presence of cholesterol-4-14C. The gy strain was grown in the presence of cholesterol-4-14C of known specific activity, the lipid extract diluted with a known amount of unlabelled cholesterol, and cholesterol isolated and purified. Its specific activity was very close to the value expected if no sterol transformations had occurred. When grown in the presence of cholestanol, the gy strain incorporated this sterol without desaturation.
Cholestanol
Strain (injury)
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The colorimetric method for the determination of total cholesterol in dog bile is consistently accurate as checked by the oxidative digitonin method. This method has the further advantages of being simple, rapid and economical. A method for the determination of esterified cholesterol in bile is described and it is shown that there are no esters of cholesterol in normal dog bile.
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Boone for cholesterol was evaluated in a 57-day growth trial. Sterol supplements were (1) cholesterol SF, whichcontained ≥91% cholesterol and ≥97% total sterol, (2) cholesterol FG, which contained ≥60% cholesterol and≥75% total sterol, and (3) sterols M1M, which contained only 21% cholesterol and 63% total sterol. Thecomposition of sterols other than cholesterol in M1M was similar to that in FG. Diets contained five levels of thesterol additives (0.0, 0.05, 0.1, 0.2, and 0.4%). Survival (64-91%) was not affected by either the level or type ofsterol supplement. Mean weight gains ranged from 1.6 g for the base diet without sterol supplements to 7.0 g forthe diet with 0.4% FG. For sterol levels above 0.05%, growth on both SF and FG was greater than on M1M.Growth increased with sterol level up to 0.4% for FG and M1M, and up to 0.2% for SF with no further increasefor 0.4% SF. The growth data suggested that the cholesterol requirement for optimum growth was satisfied byeither 0.16% cholesterol SF or 0.25% cholesterol FG, that the dietary requirement for cholesterol by L. vannameiwas 0.15%, and that sterols other than cholesterol in FG and M1M can partially, but not completely, satisfy thedietary requirement for cholesterol.
Litopenaeus
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Lanosterol
Phytosterol
Lathosterol
Cholestanol
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The sterol isolated from Rhodoglossum pulcherum was identified as cholesterol by mixed melting point of various derivatives with the corresponding derivatives prepared from authentic specimen of cholesterol. Furthermore, the identity was confirmed by X-ray diffraction analyses of the algal stenone and cholestenone. The authors also confirmed the existence of cholesterol in several red seaweed listed in Table I. Besides cholesterol, the authors isolated another sterol, chalinasterol from some algae. The discovery of cholesterol might be of some interest to biogenetic study of sterol, because cholesterol has been considered to exist only in animal sources.
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Digitonin
Cholestyramine
Coenzyme A
Hydroxymethylglutaryl-CoA reductase
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Free cholesterol is demonstrated in formalin-fixed frozen sections when treated successively by digitonin, alcohol-ether, and the Schultz technique, in which circumstances cholesterol esters are not visualized. Cholesterol esters and free cholesterol are both demonstrated in comparable sections treated by the Schultz method alone, so that the difference between such sections indicates the sites at which cholesterol esters may be considered present.
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Novel potential inhibitors of the postsqualene portion of cholesterol synthesis were screened in HepG2 cells. 2-(4-Phenethylpiperazin-1-yl)-1-(pyridine-3-yl)ethanol (LK-980) was identified as a prospective compound and was characterized further in cultures of human primary hepatocytes from seven donors. In vitro kinetic measurements show that the half-life of LK-980 is at least 4.3 h. LK-980 does not induce CYP3A4 mRNA nor enzyme activity. Target prediction was performed by gas chromatography-mass spectrometry, allowing simultaneous separation and quantification of nine late cholesterol intermediates. Experiments indicated that human sterol Δ7-reductase (DHCR7) is the major target of LK-980 (34-fold increase of 7-dehydrocholesterol), whereas human sterol Δ14-reductase (DHCR14), human sterol Δ24-reductase (DHCR24), and human sterol C5-desaturase (SC5DL) represent minor targets. In the absence of purified enzymes, we used the mathematical model of cholesterol synthesis to evaluate whether indeed more than a single enzyme is inhibited. In silico inhibition of only DHCR7 modifies the flux of cholesterol intermediates, resulting in a sterol profile that does not support experimental data. Partial inhibition of the DHCR14, DHCR24, and SC5DL steps, in addition to DHCR7, supports the experimental sterol profile. In conclusion, we provide experimental and computational evidence that LK-980, a novel inhibitor from the late portion of cholesterol synthesis, inhibits primarily DHCR7 and to a lesser extent three other enzymes from this pathway.
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