Dietary cholesterol and downregulation of cholesterol 7 alpha-hydroxylase and cholesterol absorption in African green monkeys.

Cholesterol 7 alpha-hydroxylase from human liver: partial purification and reconstruction into defined phospholipid-cholesterol vesicles.

Cholesterol 7 alpha-hydroxylase, the rate-limiting enzyme for bile acid synthesis, was shown to be copurified with human liver microsomal cytochrome P-450. When these cytochrome P-450 species were reconstituted in phospholipid-cholesterol vesicles together with NADPH-cytochrome P-450 reductase, high cholesterol 7 alpha-hydroxylase activity was obtained in the presence of NADPH. The activity rep...

Transgenic Mice. Transcriptional Level in Culture and in 7 Alpha-hydroxylase Expression at the Cholesterol and Bile Acids Regulate Cholesterol

Cholesterol and bile acids regulate cholesterol 7 alpha-hydroxylase expression at the transcriptional level in culture and in transgenic mice.

Cholesterol 7 alpha-hydroxylase (7 alpha-hydroxylase) is the rate-limiting enzyme in bile acid biosynthesis. It is subject to a feedback control, whereby high levels of bile acids suppress its activity, and cholesterol exerts a positive control. It has been suggested that posttranscriptional control plays a major part in that regulation. We have studied the mechanisms by which cholesterol and b...

Dietary Phospholipids and Intestinal Cholesterol Absorption

Experiments carried out with cultured cells and in experimental animals have consistently shown that phospholipids (PLs) can inhibit intestinal cholesterol absorption. Limited evidence from clinical studies suggests that dietary PL supplementation has a similar effect in man. A number of biological mechanisms have been proposed in order to explain how PL in the gut lumen is able to affect chole...

Absorption of dietary cholesterol in man.

Cholesterol absorption was studied by balance methods in 10 hyper!ipemic subjects. The cholesterol (401-1214 mg/day) and j:?-sitosterol (171-454 mg/ day) were integral parts of the diets. The absorption was 37% :±: 5% and the amounts of cholesterol absorbed were 149-508 mg/day. The amounts absorbed had an excellent correlation with the dietary intake of cholesterol {r = 0.98), and there was no ...