Sterol Metabolism. I. 26-Hydroxycholesterol in the Human Aorta<sup>*</sup>

Lier, Johan E. van; Smith, Leland L.

doi:10.1021/bi00862a037

Cited by 79 publications

(21 citation statements)

References 26 publications

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“…Most oxysterols with an established enzymatic origin are esterified to a great extent, whereas other oxysterols are less esterified (17). In order to determine the total or esterified oxysterols by GC, a hydrolysis step is necessary (18). However, the reaction conditions have to be chosen carefully, otherwise, cholesterol autoxidation products induced artifactually could completely mask the endogenous oxysterol levels (19).…”

Section: Discussionmentioning

confidence: 99%

Plasma oxysterols and tocopherol in patients with diabetes mellitus and hyperlipidemia

Murakami

Tamasawa

Matsui

et al. 2000

Lipids

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The plasma levels of free oxysterols (7-ketocholesterol; 7alpha-hydroxy-, 7beta-hydroxy-, 25-hydroxy-, and 27-hydroxycholesterol; and 5alpha,6alpha-epoxycholestanol) in patients with diabetes mellitus and hypercholesterolemia were determined using gas chromatography-mass spectrometry with selective ion monitoring. We studied 39 patients with diabetes mellitus, 20 nondiabetic patients with hypercholesterolemia, and 37 normal controls. Plasma cholesterol levels in diabetic and hypercholesterolemic patients showed no statistical difference. Plasma 7-ketocholesterol was significantly higher in patients with diabetes (31.6+/-2.8 ng/mL) or hypercholesterolemia (52.3+/-5.9) than in the control group (22.4+/-1.2). The increased plasma cholesterol can be regarded as an oxidation substrate for the oxidant stress and the higher absolute levels of oxysterols in hypercholesterolemic plasma compared with the control plasma. This difference disappeared when 7-ketocholesterol was expressed in proportion to total cholesterol. The oxidizability of plasma cholesterol was evaluated by comparing the increased ratio of 7-ketocholesterol after CuSO4 oxidation to the ratio before. We demonstrated that the patients with diabetes showed increased oxidizability (77.5%) compared with the control (36.6%) or hyperlipemic group (45.3%), which is likely due to the lower amounts of alpha-tocopherol in the diabetics. Measurement of oxysterols may serve as a marker for in vivo oxidized lipoproteins in diabetes and hyperlipemia.

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Section: Discussionmentioning

confidence: 99%

Plasma oxysterols and tocopherol in patients with diabetes mellitus and hyperlipidemia

Murakami

Tamasawa

Matsui

et al. 2000

Lipids

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“…25-Hydroxy-and 26-hydroxycholesterols are among the most potent inhibitors of cholesterol biosynthesis, and the former was reported by Brown and Goldstein [4] to decrease receptormediated LDL uptake in human fibroblasts: the results of our experiments indicate that such an action is shared by 26-hydroxycholesterol. 25-Hydroxycholesterol is considered an autooxidation product of cholesterol [8,17], and its occurrence in vivo as part of a metabolic pathway is disputed [I0,18]. In contrast, 26-hydroxycholesterol is the result of mitochondrial C27-steroid 26-hydroxylase [19,20], is an intermediate in the synthesis of bile acids [21], and is present in the serum of normal adults [7].…”

Section: Discussionmentioning

confidence: 99%

Regulation of low density lipoprotein metabolism by 26‐hydroxycholesterol in human fibroblasts

Lorenzo¹,

Allorio²,

Bernini³

et al. 1987

FEBS Letters

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Oxygenated derivatives of cholesterol are believed to play a role in cellular cholesterol homeostasis through the feed-back control of its biosynthesis. We report that 26-hydroxycholesterol inhibits the specific binding, uptake and degradation of t25I-LDL in human fibroblasts. The effect is dose-dependent, and saturation kinetics indicates a reduction of LDL-binding sites with no effect on iigand affinity. The results support a possible role of 26-hydroxycholesterol, a physiological oxysterol, in the regulation of cellular cholesterol homeostasis.26-Hydroxycholesterol; Oxysterol; LDL; LDL receptor; (Human fibroblast)

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“…The hydroxysterols we studied using tracer methods have not been definitely isolated from human liver (17), nor have their turnover rates been estimated. Therefore the relative extent to which they are intermediates in bile acid synthesis has not been fully defined.…”

Section: Discussionmentioning

confidence: 99%

“…On the basis of studies in animals, the 7a-hydroxylation of cholesterol to 7a-hydroxycholesterol is accepted as the major initial step in bile acid synthesis (2), and is subject to feedback regulation (22,23). The endogenous origin of 26-hydroxycholesterol seems likely as well, because it is not found in significant amounts as an air oxidation product of cholesterol (3,17,24) and can be synthesized by liver homogenate in vitro from cholesterol (3,25). Its presence in human aorta (17,(26)(27)(28) and as the sulfate in the meconium (29) and feces (30) of newborn infants infers endogenous synthesis in man.…”

Section: Discussionmentioning

confidence: 99%

Bile Acid Synthesis in Man: Metabolism of 7α-Hydroxycholesterol-14C and 26-Hydroxycholesterol-3H

Anderson¹,

Kok²,

Javitt³

1972

J. Clin. Invest.

157

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The pathways of bile acid synthesis in man were evaluated by studying the metabolism of 7a-hydroxycholesterol-4-14C and 26-hydroxycholesterol-16, 22-3H administered parenterally to individuals requiring external biliary drainage. Techniques for the identification of metabolites were thin-layer chromatography, column chromatography, gas-liquid chromatography with stream splitting, and crystallization to constant specific activity. It was found that both compounds were rapidly metabolized to bile acids and excreted in bile. Of the total radioactivity recovered in bile as bile acids, 87% of the 26-hydroxycholesterol-3H and 90% of the 7a-hydroxycholesterol-14C was found to be metabolized to both chenodeoxycholate and cholate. Compared to 7a-hydroxycholesterol, a greater proportion of 26-hydroxycholesterol was found to be metabolized to chenodeoxycholate.These findings indicate that both 7a-hydroxycholesterol and 26-hydroxycholesterol can be intermediates in the metabolism of cholesterol to bile acids in man. The observation that conversion to cholate takes place less readily after C-26 hydroxylation is consistent with previous findings in other species.

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Sterol Metabolism. I. 26-Hydroxycholesterol in the Human Aorta^*

Cited by 79 publications

References 26 publications

Plasma oxysterols and tocopherol in patients with diabetes mellitus and hyperlipidemia

Plasma oxysterols and tocopherol in patients with diabetes mellitus and hyperlipidemia

Regulation of low density lipoprotein metabolism by 26‐hydroxycholesterol in human fibroblasts

Bile Acid Synthesis in Man: Metabolism of 7α-Hydroxycholesterol-14C and 26-Hydroxycholesterol-3H

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Sterol Metabolism. I. 26-Hydroxycholesterol in the Human Aorta*

Cited by 79 publications

References 26 publications

Plasma oxysterols and tocopherol in patients with diabetes mellitus and hyperlipidemia

Plasma oxysterols and tocopherol in patients with diabetes mellitus and hyperlipidemia

Regulation of low density lipoprotein metabolism by 26‐hydroxycholesterol in human fibroblasts

Bile Acid Synthesis in Man: Metabolism of 7α-Hydroxycholesterol-14C and 26-Hydroxycholesterol-3H

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Sterol Metabolism. I. 26-Hydroxycholesterol in the Human Aorta^*