desmosterol and 4-methylcholest-7-en-3-ol

To evaluate the value of plasma cholesterol precursor sterols in the detection of bile acid malabsorption we measured these sterols in 14 familial hypercholesterolaemia patients, seven with and seven without an ileal exclusion. In the operated subjects bile acid malabsorption had induced a 4.8-fold increase in cholesterol synthesis, accompanied by a 1.9-5.1-fold increase in the plasma content of the eight cholesterol precursor sterols studied. There was no overlap between the two groups in any of these sterols, when total and free sterols were considered, and only three of the esterified sterols overlapped. The tri- and dimethyl sterols were mostly unesterified, monomethyl sterols modestly esterified and the demethylated sterols, especially desmosterol, were mainly esterified. The plasma lathosterol content segregated most clearly the patients with bile acid malabsorption from the controls. The lowest lathosterol value of the operated patients was 2.5-fold higher than the highest value of the control patients. Because lathosterol is the most abundant of the plasma cholesterol precursor sterols and is relatively easy to quantitate, it is suggested that plasma lathosterol measurement can be used in the detection of bile acid malabsorption.

Topics: Adult; Bile Acids and Salts; Cholestadienols; Cholestenes; Cholesterol; Desmosterol; Feces; Female; Humans; Hyperlipoproteinemia Type II; Ileum; Lanosterol; Male; Middle Aged; Squalene

The human bile contains several noncholesterol sterols, of which the cholesterol precursor sterols are quantitatively the most important. Detailed data on factors that regulate the amount of these sterols in the bile have not been available. In this study the effect of chronic stimulation of cholesterol synthesis on biliary cholesterol precursor sterol content was evaluated by measuring these sterols in the bile and plasma of familial hypercholesterolemia patients with and without ileal exclusion. In the operated patients cholesterol synthesis was fivefold increased, and cholesterol precursor sterols comprised 7% of the biliary sterols, compared with 2% in the control patients. All eight biliary cholesterol precursor sterols measured were significantly increased in the operated patients, and the increase was similar to that of respective sterols in plasma. Hence, the biliary methyl sterols were increased 2 to 4 times, the lathosterols 5 times, but demosterol only 1.5 times. The proportion of lathosterol was higher and that of lanosterol lower in the bile of the operated than in that of the control patients. We conclude that activation of cholesterol synthesis increases the amount of cholesterol precursor sterols in the bile in proportion to the increase of these sterols in plasma and to the overall cholesterol synthesis.

Topics: Bile; Cholestenes; Cholesterol; Desmosterol; Female; Humans; Hyperlipoproteinemia Type II; Ileum; Lanosterol; Male; Middle Aged