Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To study cholesterol metabolism in Crohn's disease and especially the effect of ileum resection, liver biopsy specimens were obtained from patients undergoing partial ileal resection because of Crohn's disease (n = 17) and patients with Crohn's colitis undergoing colectomy (n = 3). Gallstone-free patients (n = 16) undergoing cholecystectomy because of adenomyomas or polyps of the gallbladder served as controls. The mean levels of cholesterol 7 alpha-hydroxylase activity and 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, rate-determining enzymes in bile acid, and cholesterol synthesis, respectively, were twofold to threefold higher in the ileum-resected patients than in the controls. Significant positive correlations were obtained between length of resected ileum and cholesterol 7 alpha-hydroxylase activity. Provided patients who had received total parenteral nutrition preoperatively were excluded from analysis, a significant correlation was also observed between length of resected ileum and 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. Significant positive correlations were also obtained between length of resected ileum and serum levels of 7 alpha-hydroxycholesterol (a marker for bile acid biosynthesis) and lathosterol (a marker for cholesterol synthesis). The plasma levels of total and low-density lipoprotein cholesterol were negatively correlated to the length of resected ileum. The expression of hepatic low-density lipoprotein-receptor binding activity was determined in five of the patients and in three of the controls. A significant positive correlation was observed between 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and low-density lipoprotein-receptor binding activity. The results show that malabsorption of bile acids leads to parallel stimulation of cholesterol synthesis, cholesterol degradation, and low-density lipoprotein-receptor expression in human liver. The resulting effect in the present patients was a significant reduction in low-density lipoprotein cholesterol.
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PMID:Hepatic metabolism of cholesterol in Crohn's disease. Effect of partial resection of ileum. 200 2

For about a century there has been recognition that calcium and lipids bind to one another in the gut, each interfering with the other's absorption. Calcium also causes malabsorption of bile acids, which is likely to contribute further to malabsorption of fat. High dietary calcium intakes may also have stimulatory effects on lipolysis. These mechanisms provide a basis for hypothesising that calcium supplementation may impact on circulating lipid concentrations, and there is now a significant amount of observational and trial data indicating that this is the case. The largest randomised controlled trial of calcium effects on lipids was carried out in 223 healthy postmenopausal women, and found that low density lipoprotein-cholesterol (LDL-C) decreased 6.3% and high density lipoprotein-cholesterol (HDL-C) increased by 7.3% at 1-year. The resultant 16.4% increase in HDL-C/LDL-C ratio would be predicted to reduce cardiovascular event rates by 20-30%, which is consistent with the available observational data. There are no trial data addressing this question and it is possible that other lipid-lowering agents, such as hydroxymethylglutaryl coenzyme A reductase inhibitors, might impact on cardiac event rates by mechanisms other than by lowering cholesterol levels. Therefore, caution is appropriate in incorporating these findings into clinical practice, but the balance of evidence suggests that calcium is a cost-effective adjunct to the dietary management of hyperlipidaemia.
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PMID:Effects of calcium supplementation on circulating lipids: potential pharmacoeconomic implications. 1471 41