title: Transformation of 5 alpha-cholest-7-en-3 beta-ol to cholesterol and cholestanol in cerebrotendinous xanthomatosis.
abstract: The metabolism of Delta(7)-cholestenol, cholesterol, and cholestanol was examined in a patient with cerebrotendinous xanthomatosis after intravenous pulse-labeling with a mixture of dl-[2-(14)C]mevalonate and stereospecific 3S,4S,3R,4R-[4-(3)H]mevalonate. Silver nitrate and reversed-phase thin-layer chromatography were used to purify the sterols isolated from the feces, and their identities were confirmed by gas-liquid chromatography-mass spectrometry. The specific activities were determined and plotted as a function of time. Isotope ratio measurements and specific activity decay curves showed that sterol synthesis proceeded in the following sequence: mevalonate, squalene, lanosterol, Delta(7)-cholestenol, cholesterol, cholestanol. Labeled cholesterol precursors might be advantageously used to measure changes in cholesterol synthesis because they appear to equilibrate rapidly and have very short turnover times.
mesh_terms: D002250:Carbon Radioisotopes; D002782:Cholestenes / Q000378:metabolism*; D002784:Cholesterol / Q000096:biosynthesis*; D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D005243:Feces / Q000032:analysis; D005260:Female; D006801:Humans; D007553:Isotope Labeling; D013058:Mass Spectrometry; D008798:Mevalonic Acid / Q000378:metabolism; D008875:Middle Aged; D012835:Silver Nitrate; D013261:Sterols / Q000378:metabolism; D013997:Time Factors; D014316:Tritium; D014973:Xanthomatosis / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D002782:Cholestenes; D013261:Sterols; D014316:Tritium; D012835:Silver Nitrate; D002784:Cholesterol; D008798:Mevalonic Acid