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Biomedical subjects

G Salen

Publications and source records attributed to G Salen.

At least 181 records · Page 10Linked to original sources
PubMed1985

Synthesis and structure of 26 (or 27)-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24S,25 xi-pentol isolated from the urine and feces of a patient with sitosterolemia and xanthomatosis.

The urine and feces of a patient with the rare inherited lipid storage disease, sitosterolemia and xanthomatosis, were analyzed. Substantial quantities of C26-bile alcohol, 26 (or 27)-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24S,25 xi-pentol along with 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24R,25-pentol, and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol were found. The structure of the C26-bile alcohol was confirmed by direct comparison (gas-liquid chromatography-mass spectrometry and thin-layer chromatography) with a standard sample synthesized from cholic acid. The configurational assignment at C-24 was determined by lanthanide-induced circular dichroism Cotton effect measurements. The increased excretion of these C26- and C27-bile alcohols suggests an abnormality of bile acid biosynthesis in this disease.

Adolescent↗
PubMed1985

Increased plasma cholestanol and 5 alpha-saturated plant sterol derivatives in subjects with sitosterolemia and xanthomatosis.

We have measured plasma sterol composition in 14 subjects with sitosterolemia and xanthomatosis. In addition to elevated plasma phytosterol (campesterol 16 +/- 7 mg/dl and sitosterol 35 +/- 16 mg/dl) and normal to moderately high cholesterol levels (258 +/- 96 mg/dl), concentrations of 5 alpha-saturated stanols, cholestanol, 5 alpha-campestanol, and 5 alpha-sitostanol were at least 10 times greater than controls. Diets contained plentiful quantities of cholesterol and plant sterols, but only trace amounts of cholestanol (less than 2 mg/day) and no detectable 5 alpha-campestanol and 5 alpha-sitostanol, which indicated that the 5 alpha-saturated stanols were formed endogenously. Treatment with cholestyramine reduced plasma cholesterol and phytosterol levels by 45% and 5 alpha-saturated stanols by 55%. These results indicate that abnormally high plasma concentrations of cholestanol, 5 alpha-campestanol, and 5 alpha-sitostanol are found in subjects with sitosterolemia and xanthomatosis, and that treatment with cholestyramine effectively reduced elevated plasma sterol levels.

Adolescent↗
PubMed1985

Effect of chenodeoxycholic acid on biliary and urinary bile acids and bile alcohols in cerebrotendinous xanthomatosis; monitoring by high performance liquid chromatography.

Biliary and urinary bile alcohol and bile acid composition has been determined by high performance liquid chromatography in patients with cerebrotendinous xanthomatosis before and after treatment with chenodeoxycholic acid. Most of the bile acids and bile alcohols in the bile and urine were separated in less than 30 min using a radial pack C18 muBondapak 5 micron particle size column with a mobile phase of acetonitrile-water-methanol-acetic acid 70:70:20:1 (v/v/v/v) at a flow rate of 2 ml/min, and a refractive index detector. Before treatment, cholic acid (49%) and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 25-tetrol (27%) were the major biliary bile acid and bile alcohol, respectively, but were not detected in the urine of five patients. 5 beta-Cholestane-pentols were, instead, the major urinary bile alcohols with 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23 xi, 25-pentol (56%) predominating. Whereas 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 24S,25-pentol was not detected in the bile, it was isolated in the urine of all patients (27%). The only urinary bile acid isolated by high performance liquid chromatography was nor-cholic acid. After 1 month of treatment with chenodeoxycholic acid, 0.75 g/day, chenodeoxycholic acid became the major bile acid in the bile of all patients (71%) along with its metabolite, ursodeoxycholic acid (21%). Cholic acid and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 25-tetrol were drastically reduced and were only 3% each. The excretion of 5 beta-cholestane-pentols in the urine was also drastically reduced from 130 mg/day to 15 mg/day.

Bile↗
PubMed1985

Lethal atherosclerosis associated with abnormal plasma and tissue sterol composition in sitosterolemia with xanthomatosis.

Tissue sterol composition was determined in an 18-year-old male with sitosterolemia with xanthomatosis who died suddenly and whose coronary and aortic vessels showed extensive atherosclerosis and, for comparison, in an 18-year-old male with minimal atherosclerosis who died accidently. Sterols in the control tissues (plasma, erythrocytes, cardiac muscle, lung, liver, aorta, and brain) contained cholesterol with only trace amounts of cholestanol. In contrast, sterols in corresponding tissues of the sitosterolemic subject (except brain) were composed of cholesterol, increased amounts of plant sterols, campesterol and sitosterol, and 5 alpha-saturated stanols, cholestanol, 5 alpha-campestanol, and 5 alpha-sitostanol, that were deposited in approximately the same ratio as present in plasma. However, sitosterolemic brain sterol composition resembled that of the control brain with cholesterol and only trace amounts (less than 1%) of cholestanol and phytosterols. The sitosterolemic aorta was extensively atherosclerotic and contained more than twice the quantity of sterols as the control aorta (5.6 mg/g versus 2.6 mg/g) with increased amounts of cholesterol, plant sterols, and 5 alpha-saturated stanols. These results indicate that cholesterol, plant sterols, and 5 alpha-stanols are deposited prematurely and are associated with accelerated atherosclerosis in subjects with sitosterolemia with xanthomatosis.

Adolescent↗
PubMed1984

Long-term treatment of cerebrotendinous xanthomatosis with chenodeoxycholic acid.

We studied the effect of chenodeoxycholic acid in 17 patients with cerebrotendinous xanthomatosis. Before treatment, all subjects were symptomatic, with Achilles tendon xanthomas (in 15 of 17), cataracts (in 12 of 17), dementia (in 13 of 17), pyramidal-tract signs (in all 17), cerebellar dysfunction (in 13 of 17), mild peripheral neuropathy (in 7 of 17), electroencephalographic abnormalities (in 10 of 13), and abnormal cerebral computerized axial tomographic scans (in 10 of 12). After at least one year of chenodeoxycholic acid treatment (750 mg per day), dementia cleared in 10 subjects, and pyramidal and cerebellar signs disappeared in 5 and improved in another 8. Peripheral neuropathy was no longer detected in six. The electroencephalogram became normal in five and showed fewer abnormalities in another three subjects. Cerebral computerized axial tomographic scans improved in seven patients; the changes included the disappearance of a cerebellar xanthoma in one case. Concomitantly, mean plasma cholestanol levels declined threefold, and abnormal bile acid synthesis was suppressed. We conclude that long-term therapy with chenodeoxycholic acid may correct the biochemical abnormalities and arrest and possibly reverse the progression of cerebrotendinous xanthomatosis.

Adolescent↗
PubMed1984

Substrate specificity of cholylglycine hydrolase for the hydrolysis of bile acid conjugates.

The substrate specificity of cholylglycine hydrolase has been investigated using bile acid conjugates with modifications in the steroid ring system, the side chain, or the amino acid moiety. Epimerization at C-3 and C-7 did not affect the activity of the enzyme while oxidation of the three nuclear hydroxyl groups reduced the affinity of the enzyme toward the substrate. Elongation of the side chain by one or three carbons inhibited enzyme activity. Conjugates prepared from C24 bile acids and analogs of taurine and glycine with one or two methylene groups were effectively hydrolyzed, whereas conjugates with a tertiary amide group completely resisted hydrolysis. Increasing the length of the bile acid side chain or using a bile acid conjugate with a tertiary amide group may produce compounds that will resist intestinal bacterial destruction.

Amidohydrolases↗
PubMed1984

Comparative effects of cholestanol and cholesterol on hepatic sterol and bile acid metabolism in the rat.

Large amounts of cholestanol, the 5 alpha-dihydro derivative of cholesterol are found in tissues of patients with the rare inherited sterol storage disease cerebrotendinous xanthomatosis. Although small amounts of cholestanol are present in virtually every tissue of normal man, little is known about its metabolism and effect on cholesterol and bile acid formation. The purpose of this study is to investigate the absorption and metabolism of cholestanol and its early effects on hepatic morphology and on the rate-limiting enzymes of cholesterol and bile acid biosynthesis. After 2 wk on a diet supplemented with 2% cholestanol, total liver sterol content increased by 48% (3.26 vs. 2.20 mg/g), and resulted in a significant rise in hepatic cholestanol concentration to 1.4 mg/g. However, cholestanol was less efficiently absorbed from the intestine than cholesterol and interfered with cholesterol absorption. Furthermore, hepatic hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase activity rose 2.6-fold (from 150.3 to 397.0 pmol/mg per min) during cholestanol feeding, and was associated with a marked proliferation of the smooth endoplasmic reticulum of the centrilobular areas. In addition, significant amounts of allocholic acid (16%) and allochenodeoxycholic acid (5%) were formed from cholestanol and excreted in the bile. These results show that cholestanol is absorbed from the intestine, interferes with cholesterol absorption, and is deposited in the liver. However, in contrast to cholesterol, cholestanol feeding was associated with a marked elevation of HMG-CoA reductase activity. Thus, despite structural similarity between cholesterol and its 5 alpha-saturated derivative, cholestanol does not exert feedback inhibition on hepatic cholesterol biosynthesis.

Animals↗
PubMed1984

Synthesis of the putative metabolites of plant sterols: (24R)- and (24S)-24-methyl-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrols and 24-ethyl-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi-tetrol.

This report describes the synthesis of (24R)- and (24S)-24-methyl-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrols and 24-ethyl-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi-tetrol starting from cholic acid. The bile alcohols epimeric at C-24 were resolved by analytical and preparative thin-layer chromatography and characterized by gas-liquid chromatography and mass spectrometry. These epimeric bile alcohols may be useful for studying the transformation of beta-sitosterol to cholic acid.

Animals↗
PubMed1984

Transformation of 4-cholesten-3-one and 7 alpha-hydroxy-4-cholesten-3-one into cholestanol and bile acids in cerebrotendinous xanthomatosis.

In order to determine whether cholestanol and bile acids are derived from the same precursor, key intermediates of both biosynthetic pathways beyond cholesterol were administered intravenously to a patient with cerebrotendinous xanthomatosis and to a control subject. After pulse-labeling with [4-14C]4-cholesten-3-one and [G-3H]7 alpha-hydroxy-4-cholesten-3-one, cholestanol, cholesterol, and the two primary bile acids, cholic acid and chenodeoxycholic acid were isolated from specimens of bile. Each compound was purified by thin-layer chromatography and conclusively identified by gas-liquid chromatography-mass spectrometry. In other studies, the in vitro formation of 4-cholesten-3-one from cholesterol was measured in hepatic microsomal fractions prepared from a subject with cerebrotendinous xanthomatosis and from 3 control individuals. In all subjects, cholic acid and chenodeoxycholic acid were labeled with tritium, but neither cholesterol nor cholestanol contained this isotope. In contrast, 14C was detected in the cholestanol fraction with trace amounts in chenodeoxycholic acid, cholic acid, and cholesterol. Hepatic microsomes prepared from liver biopsy specimens obtained from a subject with cerebrotendinous xanthomatosis produced three times more 4-cholesten-3-one than the controls. The results indicate that 4-cholesten-3-one was converted primarily into cholestanol and 7 alpha-hydroxy-4-cholesten-3-one into cholic acid and chenodeoxycholic acid. Neither ketonic steroid was transformed into cholesterol. The increased production of cholestanol in cerebrotendinous xanthomatosis may be accounted for by enhanced hepatic formation of 4-cholesten-3-one. 7 alpha-Hydroxy-4-cholesten-3-one is a precursor of bile acids, but not of cholestanol.

Adult↗
PubMed1984

Stereospecific synthesis of 3 beta-hydroxylated bile alcohols.

This paper describes the synthesis of 5 beta-cholestane-3 beta, 7 alpha,25-triol and 5 beta-cholestane-3 beta, 7 alpha, 12 alpha, 25-tetrol from their corresponding 3 alpha-analogs. The method consists of refluxing a mixture of a steroid alcohol, triphenylphosphine, and diethyl azodicarboxylate in benzene solution with an acid such as formic acid. The sterically pure ester (3 beta-formate) so formed after saponification then allows an easy access to the epimer of the starting alcohol. Differentiation of these 3 beta-hydroxy bile alcohols from their corresponding 3 alpha-epimeric analogs was made possible on the basis of proton, 13C-NMR, and mass spectra as well as chromatographic mobility. Steric requirements of sterols and nucleophilicity of attacking acidic components played an important role for the success of this synthesis. Only equatorial hydroxyl groups in these bile alcohols reacted under mild conditions and epimerization, as well as protection of the alcoholic group, was achieved in one step. Formic acid was the acid of choice since the axial formate ester formed is sufficiently reactive to be hydrolyzed (KHCO3/aq X MeOH) under mild conditions.

Bile Acids and Salts↗
PubMed1983

Sitosterol and cholesterol metabolism in a patient with coexisting phytosterolemia and cholestanolemia.

Sitosterol and cholesterol metabolism were studied in a patient with coexisting phytosterolemia and cholestanolemia, and in a control subject, both on similar diets containing about 170 mg cholesterol and 135 mg phytosterols per day. The turnover of 22,23-3H-sitosterol and 4-14C-cholesterol, given intravenously, were followed for up to 372 days. The specific activity-time curves for both sterols were resolved into two exponentials and fitted into a two-pool model. The half-lives of both exponential curves for sitosterol, in the patient, were abnormally long. Equilibration of the tracer between the two pools, in the patient, occurred at about 30 days as compared to 10-15 days in the control subject. The daily turnover of sitosterol in the patient was estimated to be 10 times greater than that in the control subject. The patient's total body exchangeable pool of sitosterol was 9.6 g or about 80 times the amount found in the control. The patient's plasma phytosterol levels fell by 25% when he went on a diet containing only 10 mg phytosterols per day. During this period the specific activity of his plasma sitosterol with respect to an equilibrated dose of 3H-labeled tracer remained constant; this was compatible with the absence of endogenous synthesis. Cholesterol turnover in the patient showed prolonged half-lives for both exponential curves and reduced fractional daily loss from the fast-exchanging pool. The patient's xanthoma sterols underwent 16% and 55% exchange with plasma sitosterol and cholesterol, respectively, on day 60, indicating the presence of a third exchangeable pool.

Adult↗
PubMed1983

A facile synthesis of [3 alpha-3 H]beta -sitosterol.

Direct oxidation of the parent sterol using CrO3 provided (24R)-24-ethyl-5-cholesten-3-one which on treatment with NaBT4 gave [3 alpha-3 H] (24R)-24-ethyl-5-cholesten-3 beta-ol. Purification at each stage afforded samples which were compared spectrally with the corresponding cholesterol series compounds.

Chromatography, Gas↗
PubMed1983

Bile acid synthesis.

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Bile Acids and Salts↗
PubMed1983

Configuration at C-25 in 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid isolated from human bile.

This report describes the isolation of the natural isomer of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid from human bile by a method that retains the configuration at C-25. The stereochemistry at C-25 in this bile acid was defined as 25R by a direct comparison with standard (25R)3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid.

Bile↗
PubMed1983

Synthesis of 3 alpha,7 alpha,12 alpha,25-tetrahydroxy-5 beta-cholestan-24-one, an intermediate in the 25-hydroxylation pathway of cholic acid biosynthesis from cholesterol.

This paper describes the chemical synthesis of 3 alpha,7 alpha,12 alpha,25-tetrahydroxy-5 beta-cholestan-24-one via selective oxidation of 5 beta-cholestane-3 alpha,7 alpha,12 alpha, 24 xi,25-pentol with silver carbonate on celite. The structure of this 24-keto bile alcohol was confirmed by gas-liquid chromatography and mass spectrometry. Synthesis of this compound via pyridinium chlorochromate oxidation of the triacetoxy derivative of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi,25-pentol followed by saponification further established its structure. 3 alpha,7 alpha,12 alpha,25-Tetrahydroxy-5 beta-cholestan-24-one was required for the in vivo and in vitro studies of side-chain oxidation and cleavage in the 25-hydroxylation pathway of cholic acid biosynthesis.

Cholestanols↗