Observations of the metabolism of peripheral leukocytes in acute leukemia. II. Uridine and phenylalanine incorporation.
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Adult↗
Biomedical subjects
G Salen
Publications and source records attributed to G Salen.
The effect of tauroursodeoxycholic acid and taurine supplementation on biliary bile acid composition.
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Bile Acids and Salts↗
Early morphologic and enzymatic changes in livers of rats treated with chenodeoxycholic and ursodeoxycholic acids.
The effect of high doses of chenodeoxycholic and ursodeoxycholic acids on hepatic morphology and on cholesterol and bile acid metabolism was examined in the rat. After 2 weeks of either cheno or ursodeoxycholic acid feeding, the livers of the treated rats revealed marked proliferation of the smooth endoplasmic reticulum which appeared as an adaptation phenomenon of the microsomal enzyme system in response to bile acid intake. However, the livers of the chenodeoxycholic acid-treated rats showed early alteration that included mild triaditis, swelling of the bile canalicular microvilli, distended Golgi vesicles, whorling of the mitochondria, and presence of large vacuoles bound by single membranes. During cheno- or ursodeoxycholic acid treatment, the administered bile acid predominated in the bile and amounted to 79 or 67% of the biliary bile acids, respectively. At the same time, the concentration of the muricholic acids was also increased. Biliary cholic acid content dropped significantly, but no change in lithocholic acid concentration was observed. In addition, the activity of HMG-CoA reductase as well as that of cholesterol-7 alpha-hydroxylase was reduced by either of the administered bile acids, while no change in hepatic cholesterol content was detected, and intestinal cholesterol absorption was not significantly different from that of controls. These results show that cheno- and ursodeoxycholic acids inhibited hepatic cholesterol and bile acid synthesis but did not increase either intestinal cholesterol absorption or hepatic microsomal cholesterol content. Since the amounts of biliary lithocholic acid were similar in the bile acid-treated animals, the morphologic abnormalities detected in the chenodeoxycholic acid-fed rats are probably due to an increased pool of chenodeoxycholic acid. However, lithocholic acid-induced liver injury cannot be excluded.
Animals↗
Transformation of bile acids into iso-bile acids by Clostridium perfringens: possible transport of 3 beta-hydrogen via the coenzyme.
We have examined the mechanism for the bacterial transformation of chenodeoxycholic acid and lithocholic acid into the corresponding 3 beta-hydroxy epimers with the use of 3 alpha- and 3 beta-tritiated bile acids. The 3-oxo bile acids were transformed into the 3 alpha- (85%) and 3 beta- (15%) hydroxy bile acids after 20-hr incubation with Clostridium perfringens. Approximately 75% radioactivity was recovered in the aqueous medium when [3 beta-3H]chenodeoxycholic acid or [3 beta-3H]lithocholic acid was incubated with the bacteria, and approximately 15% of radioactivity in the bile acid fraction was associated with the 3 alpha-position of the iso-bile acids. When [3 beta-3H]chenodeoxycholic acid was incubated with unlabeled 3-oxo-5 beta-cholanoic acid, tritiated litho- and iso-lithocholic acids were recovered. These results can be explained only when a 3-oxo intermediate is postulated, and the 3 beta-hydrogen in the bile acids is transferred by the bacterial coenzyme (NAD+ or NADP+) to the 3 alpha-position in the iso-bile acids during the reduction of the 3-oxo compounds.
Bile Acids and Salts↗
Blocking cholesterol synthesis impairs acquisition of the classically conditioned eyeblink response.
Smith-Lemli-Opitz (SLO) syndrome is a congenital disorder characterized by severe mental retardation. Patients with SLO lack 7-dehydrocholesterol (7 dH) reductase, which catalyzes the last step of cholesterol synthesis. Administration of an agent that blocks 7 dH cholesterol reductase, BM 15.766 (BM), leads to a biochemical profile which resembles that of SLO patients, i.e., lower plasma, liver, and brain cholesterol levels accompanied by the appearance of the precursors 7 dH and 8 dH cholesterol. In this article we address the functional consequences of chronic BM treatment on new motor learning by assessing acquisition of the classically conditioned eyeblink response. Just-weaned rats were fed BM by gavage for four months, with half of these rats given exogenous cholesterol during the last two months of BM treatment. Acquisition of the eyeblink response was impaired in BM-treated rats. Impaired acquisition of the eyeblink response was not accompanied by alterations in responsiveness to either the conditioned or unconditioned stimulus. Exogenous cholesterol, a clinically relevant countertreatment, failed to correct for the learning impairment produced by BM treatment. Chronic treatment with a cholesterol synthesis-blocking agent impaired associative learning in just-weaned rats.
Animals↗
Characterization of the biochemical abnormality in the Smith-Lemli-Opitz syndrome.
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Biomarkers↗
Inhibition of cholesterol biosynthesis by chenodeoxycholic acid in the rhesus monkey.
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Animals↗
Chromatographic separation of putative precursors of cholestanol.
This paper describes convenient syntheses for labeled and unlabeled cholest-5-en-3-one, cholest-4-en-3-one, epicholesterol, cholest-4-en-3 beta-ol, and cholest-4-en-3 alpha-ol. The thin-layer chromatography, high-performance liquid chromatography, and gas-liquid chromatography of these compounds and of cholestanol and epicholestanol are also described. The synthesized compounds are potential precursors in the biosynthesis of cholestanol in mammals.
Cholestanols↗
Tuberous xanthomas in sitosterolemia.
Sitosterolemia is an autosomal recessive lipid disorder in which plasma plant sterol levels are extremely elevated and cholesterol levels are often elevated but may be normal. Clinically sitosterolemia is characterized by xanthomas, premature vascular disease, and arthritis. Adolescent boys and girls with sitosterolemia are susceptible to fatal cardiac events. Dermatologists may have a vital role in the diagnosis of this rare but serious condition because early detection and treatment are important in preventing the associated atherosclerotic heart disease. We present a 7-year-old girl with sitosterolemia and tuberous xanthomas.
Anticholesteremic Agents↗
Cerebrotendinous xanthomatosis: A cause of cataracts and tendon xanthoma.
Patients with cerebrotendinous xanthomatosis may present with adolescent-onset cataracts and tendon xanthomas, and can have progressive neurological, myocardial, pulmonary, and endocrine dysfunction leading to death. The disease is inherited as an autosomal recessive and results in increasing deposition of cholesterol and cholestanol in vital organ systems; the primary biochemical abnormality is a block in bile acid synthesis which is manifested by a diminished pool of chenodeoxycholic acid. Replacement therapy with chenodeoxycholic acid may reduce cholesterol and cholestanol production.
Achilles Tendon↗
Antenatal therapy of Smith-Lemli-Opitz syndrome.
OBJECTIVES: Smith-Lemli-Opitz syndrome (SLOS) is a recessively inherited disorder caused by an inborn error of cholesterol metabolism that results in deficiency of cholesterol and accumulation of the cholesterol precursor, 7-dehydrocholesterol (DHC) and its epimer, 8-DHC. Affected patients present with congenital anomalies, growth restriction, and mental retardation. Postnatal treatment with cholesterol supplementation has been shown to improve plasma sterol levels and has resulted in improved growth and development in many patients. We hypothesized that prenatal supplementation of cholesterol could potentially arrest some of the adverse consequences of cholesterol deficiency at an earlier stage of development. METHODS: SLOS was diagnosed in the third trimester in a fetus initially identified by sonography with intrauterine growth restriction and ambiguous genitalia and confirmed by elevated levels of 7- and 8-DHC in amniotic fluid. Antenatal supplementation of cholesterol was provided by fetal intravenous and intraperitoneal transfusions of fresh frozen plasma (cholesterol level = 219 mg/dl). RESULTS: The in utero transfusions resulted in increased levels of fetal cholesterol, as measured in blood samples obtained by cordocentesis. In addition, fetal red cell mean corpuscular volume rose, which further indicated that the exogenous cholesterol was incorporated into the fetal erythrocytes. CONCLUSIONS: Antenatal treatment of SLOS by cholesterol supplementation is feasible and results in improvement in fetal plasma cholesterol levels and fetal red cell volume. SLOS may be added to the growing list of human genetic disorders for which prenatal diagnosis is available and therapeutic intervention may be possible.
Cholesterol↗
Unexpected failure of bile acid malabsorption to stimulate cholesterol synthesis in sitosterolemia with xanthomatosis. Comparison with lovastatin.
We examined the relationship between cholesterol synthesis and high affinity low density lipoprotein (LDL) catabolism in freshly isolated mononuclear leukocytes and plasma sterols and apolipoprotein concentrations in three homozygous and one heterozygous subject with sitosterolemia with xanthomatosis and in 12 control subjects. Observations in untreated subjects were compared during therapy with lovastatin or interruption of the enterohepatic circulation of bile acids. Plasma cholesterol, plant sterol, and apolipoprotein B concentrations declined more than 50% in the two homozygous sitosterolemic subjects after ileal bypass surgery. In contrast, plasma cholesterol, plant sterol, and apolipoprotein B concentrations remained constant in a homozygous sitosterolemic subject and declined only 7% in a heterozygous sitosterolemic subject during 20 weeks of lovastatin (40 mg/day) treatment compared to a 28% decrease in similarly treated control subjects. Lovastatin treatment decreased cholesterol synthesis more than 60% but did not increase high affinity catabolism of LDL further in the sitosterolemic cells, compared to a more than 20% rise in control mononuclear leukocytes. Conversely, bile acid malabsorption increased cholesterol synthesis 59%, total hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase activity 13%, and receptor-mediated LDL degradation 41% in control cells, but did not stimulate cholesterol synthesis or microsomal HMG-CoA reductase activity in sitosterolemic mononuclear leukocytes although receptor-mediated LDL catabolism rose an additional 26%. These results demonstrate a greater than expected decrease in plasma sterols and apolipoprotein B concentrations in sitosterolemic subjects after stimulation of bile acid synthesis because of the inability to up-regulate cholesterol production. We suggest that bile acid-sequestering drugs or ileal exclusion surgery may be more effective treatments to mobilize accumulated sterol deposits and prevent atherosclerosis in this disease.
Adult↗
A multicenter placebo-controlled clinical trial of oral metoclopramide in diabetic gastroparesis.
Metoclopramide tablets were compared with placebo in the treatment of gastrointestinal symptoms in 40 patients with diabetic gastroparesis. Results of a 3-wk double-blind study indicate that metoclopramide at a dosage of one 10-mg tablet four times daily reduced nausea, vomiting, fullness, and early satiety and improved meal tolerance better than placebo. Statistically significant differences were noted for nausea and postprandial fullness. Mean gastric emptying assessed by radionuclide scintigraphy was significantly improved in the metoclopramide-treated group when compared with their baseline result. Metoclopramide is an effective agent for improving the upper gastrointestinal motor function in diabetic patients with gastroparesis.
Administration, Oral↗
Competitive inhibition of hepatic sterol 27-hydroxylase by sitosterol: decreased activity in sitosterolemia.
We investigated the effect of sitosterol on hepatic sterol 27-hydroxylase activities in subjects with sitosterolemia, a recessive inherited disease associated with accelerated atherosclerosis and increased levels of sitosterol and other plant sterols and stanols in tissues. Hepatic activities of mitochondrial sterol 27-hydroxylase, which catalyzes the first step in the conversion of cholesterol to bile acids via the acidic bile acid synthetic pathway, were measured in liver tissues and related to hepatic microsomal cholesterol 7 alpha-hydroxylase, which controls the rate of bile acid synthesis via the neutral synthetic pathway. These measurements of cholesterol catabolism were correlated to sterol concentrations and composition in plasma and liver. Sterol 27-hydroxylase activities in liver mitochondria of three homozygous sitosterolemic subjects were 68% lower than in 10 control subjects (p < .05) and were associated with increased levels of plant sterols in both plasma and liver (13% and 16% of total sterols, respectively, compared to trace amounts in controls). Analysis of Lineweaver-Burk double reciprocal plots of sterol 27-hydroxylase activities in control human liver specimens (where mitochondrial sterol 27-hydroxylase activities were measured with increasing concentrations of the cholesterol substrate, in the absence and presence of 100 microM and 300 microM sitosterol) revealed that sitosterol inhibited mitochondrial sterol 27-hydroxylase activity up to 50% by a competitive mechanism. In sitosterolemic subjects, competitive inhibition of hepatic sterol 27-hydroxylase activity by sitosterol was associated with competitively inhibited microsomal cholesterol 7 alpha-hydroxylase activity (averages from 4 sitosterolemic homozygotes and 14 controls were 12.4 +/- 1.9 and 23.6 +/- 2.5 pmol/mg/min, respectively). Furthermore, decreased cholesterol catabolism in sitosterolemic subjects was associated with significantly elevated plasma cholesterol concentrations (232 +/- 17 mg/dl, as compared to 180 +/- 13 mg/dl in controls) but with no change in hepatic cholesterol concentrations. In an animal model (rats infused intravenously with sitosterol-containing liposomes that increased sitosterol in the liver and plasma to levels similar to those found in sitosterolemic subjects), hepatic mitochondrial sterol 27-hydroxylase and microsomal cholesterol 7 alpha-hydroxylase activities also decreased significantly and were coupled to markedly elevated plasma sterol concentrations (120.7 +/- 12.5 mg/dl, as compared to 59.2 +/- 6.3 mg/dl in control animals; p < .05) but to no change in hepatic cholesterol concentrations. Thus, decreased cholesterol catabolism due to competitive inhibition of both microsomal cholesterol 7 alpha-hydroxylase and mitochondrial sterol 27-hydroxylase by elevated hepatic sitosterol concentrations contributes to hypercholesterolemia and increased risk of atherosclerosis in sitosterolemia.
Animals↗