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)

Cholesterol balance studies were carried out twice in a young male patient with homozygous familial hypercholesterolemia. At 13 mo, cholesterol balance in this patient averaged 31.3 mg/kg per d, and bile acid excretion was 12.0 mg/kg per d; at 3 yr, results were similar, 27.3 and 15.5 mg/kg per d for cholesterol balance and bile acids, respectively. A normal boy of 3 yr was also studied for comparison with the second study in our patient. Cholesterol balance and bile acid outputs in the normal child were 11.5 and 3.3 mg/kg per d, respectively. Thus, in comparison with the normal child, the patient with homozygous familial hypercholesterolemia had a marked increase in synthesis of cholesterol and bile acids. Although synthesis of bile acids was high in this patient, the fraction of newly synthesized cholesterol converted into bile acids (40-56%) was in the normal range; this suggests that the enhanced output of bile acids was secondary to an increased synthesis of cholesterol and not to malabsorption of bile acids, which likely would have produced a higher fractional conversion. Although our patient has been studied at a younger age than any reported in the literature, two similar children 5 and 6 yr of age were also observed to have elevated cholesterol synthesis. This finding contrasts with those in older children with the homozygous as well as heterozygous forms of this disease who appear to have normal synthesis of cholesterol and bile acids. Therefore, increased synthesis of cholesterol seems to be characteristic of early homozygous familial hypercholesterolemia, and may be a manifestation of a loss of feedback inhibition of cholesterol synthesis secondary to an absence of specific cell-surface receptors for low density lipoproteins. However, as children with this disease grow older, other mechanisms may come into play to restore cholesterol synthesis to normal levels.
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PMID:Elevated cholesterol and bile acid synthesis in a young patient with homozygous familial hypercholesterolemia. 46 90

Interrelationships between oral contraceptives and dietary lipids on iron and copper levels in plasma and tissues were investigated in rats. Diets containing either 20% (by weight) safflower oil or hydrogenated coconut oil with and without cholesterol (0.5%) were fed to weanling, female, Wistar-strain rats for a period of 19 weeks. Three types of oral contraceptive agents differing in estrogen/progesterone ratios were administered during weeks 16 through 19 of the experiment. Control rats received the dietary treatment without oral contraceptives. Hemoglobin concentration, hematocrit, red blood cell counts, mean cell hemoglobin and hemoglobin concentration, and mean cell volume values were similar among the various dietary and drug-treatment groups. Elevated levels of copper were found in livers of drug-treated animals fed diets containing cholesterol and safflower oil, whereas levels of copper or iron in spleen and kidney were not influenced by oral contraceptives. Dietary safflower or coconut oil had no influence on levels of iron or copper in plasma. However, iron levels were higher in liver, spleen, and kidneys of rats fed coconut oil compared with those fed safflower oil. Cholesterol-fed rats had reduced levels of iron in plasma and tissues and increased levels of copper in plasma and liver. Iron deficiency in cholesterol-fed rats was indicated by low levels of iron in plasma, liver, spleen, and kidney. In experiment 2, animals were fed the 20% safflower oil diet, with and without sodium glycocholate or cholesterol, to determine whether the apparent malabsorption of iron resulted from sodium glycocholate or cholesterol. Sodium glycocholate resulted in a marked increase in the absorption of iron, whereas cholesterol depressed absorption.
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PMID:Influence of dietary lipids on iron and copper levels of rats administered oral contraceptives. 115 20

Malabsorption of bile acid increases cholesterol synthesis and activates hepatic LDL receptors which leads to enhanced elimination of cholesterol from the body. Interruption of enterohepatic circulation of bile acids may lead to a smaller bile acid pool, which, in turn, impairs cholesterol and fat absorption by reduced micellar solubilization. Together with reduced cholesterol absorption, the increased cholesterol loss as bile acids also reduces plasma cholesterol concentrations and the biliary cholesterol excretion, too. Diminished biliary cholesterol in bile acid malabsorption may contribute to the increased incidence of gallstones associated with ileal dysfunction. Malabsorption of bile acid leads to a fall in LDL-cholesterol concentration, and an increase of HDL-cholesterol concentration has been reported. VLDL-triglyceride concentrations are almost invariably raised. Enhanced cholesterol and bile acid synthesis in ileal dysfunction is reflected by raised concentrations of plasma cholesterol precursors, especially lathosterols, which can be used as an indicator of increased bile acid loss to faeces. Cholesterol absorption, in turn, correlates positively with plasma plant sterol concentrations levels and the ratio of lathosterols to campesterols can be used as a screening measurement for ileal dysfunction. Plasma fatty acid composition is also altered as a response to fat malabsorption associated with ileal dysfunction. The proportion of essential fatty acids is inversely correlated with faecal fat excretion and endogenous fatty acid synthesis is activated.
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PMID:Lipid metabolism in bile acid malabsorption. 218 46

The role of cholesterol and bile acid malabsorption in the regulation of plasma plant sterol levels was studied in 30 patients with an ileal resection (seven without any malabsorption, eight with bile acid malabsorption alone and 15 with bile acid, fat and cholesterol malabsorption) and nine with jejunoileal bypass (modest bile acid, and severe cholesterol and fat malabsorption). In contrast to cholesterol, plant sterols are not synthesized by the body, and so the plasma levels are regulated by their intestinal absorption and biliary secretion. In fact, the plant sterol, especially campesterol, levels were low in patients with cholesterol and fat malabsorption. Cholesterol absorption efficiency was a significant determinant of the plant sterol levels, suggesting that it reflects overall sterol absorption efficiency and that the plasma plant sterol levels, in turn, reflect cholesterol absorption. Bile acid malabsorption, though it appeared to promote biliary plant sterol secretion, had little direct effect on the plasma plant sterol contents. The results indicate that plasma campesterol levels can be used to evaluate cholesterol absorption efficiency in general and may reveal clinically significant steatorrhoea in patients with gut exclusion.
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PMID:Regulation of plasma plant sterol levels in patients with gut resections. 320 Nov 6

Cholesterol synthesis was studied in intestinal biopsies obtained from children with different forms of malabsorption syndrome. It was demonstrated that intestinal cholesterol synthesis is enhanced in celiac disease and several other forms of malabsorption syndrome. Mevinolin inhibited intestinal cholesterol synthesis in all groups of patients. No correlation was found between cholesterol synthesis and age and sex of the patients, clinical manifestation of the disease and plasma cholesterol level.
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PMID:Cholesterol synthesis in the small intestine of patients with malabsorption syndrome. 323 21

Cholesterol synthesis, faecal bile acids and neutral sterols, and plasma squalene and free and esterified cholesterol precursor sterols concentrations were studied in patients with previous ileal resection (n = 30) or jejunoileal bypass (n = 9) to elucidate the responses of different cholesterol precursors to enhanced cholesterol synthesis induced by cholesterol and bile acid malabsorption. A subgroup of seven resection patients without fat and bile acid malabsorption served as controls. Of the resection patients, eight had a pure bile acid malabsorption and 15 a combination of fat, bile acid, and modest cholesterol malabsorption. In the patients with jejunoileal bypass, cholesterol and fat absorption was greatly decreased in addition to bile acid malabsorption. The overall cholesterol synthesis was associated with proportionately increased plasma contents of free (and, less consistently, esterified) methyl sterols, the most marked increase, up to 18 times, being recorded for free and esterified lathosterols. The concentrations of the precursor sterols were similarly increased in the subjects with bile acid and cholesterol malabsorption, the two lathosterols showing the highest correlations with the overall cholesterol synthesis (r = 0.820-0.941). In the subjects with jejunoileal bypass cholesterol malabsorption effectively regulated cholesterol synthesis and the precursor levels. Gut exclusions large enough to cause cholesterol and/or bile acid malabsorption activate cholesterol synthesis leading to a proportional elevation in the plasma concentrations of cholesterol precursors, especially in those of lathosterols and free methyl sterols. Determination of the plasma concentration of total lathosterol by a single gas-chromatographic run is a suitable method for rapid screening of clinically significant cholesterol and bile acid malabsorption.
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PMID:Raised plasma cholesterol precursors in patients with gut resections. 334 29

Cholesterol and bile acid metabolism and vitamin B12 were studied in 19 patients with heterozygous familial hypercholesterolemia in an 8-yr follow-up (3-12 yr after ileal bypass operation), and in 11 unoperated controls. Absorption of cholesterol and vitamin B12 were decreased by the operation, but improved slowly, and at 8 yr cholesterol absorption was normal. Cholesterol excretion as fecal neutral steroids was not increased by the operation, and at 8 yr the flux of endogenous cholesterol to the gut was similar in the operated and control patients. Cholesterol absorption was positively correlated with mouth to anus transit time in the unoperated patients. Fecal bile acid excretion was increased immediately after the operation and continued to increase even after the second postoperative year. In the operated patients fecal excretion of fat, water, and dry matter were positively correlated with fecal bile acid excretion. Our study suggests that adaptive changes occur slowly after ileal bypass, resulting in gradual normalization of cholesterol absorption, despite continuing bile acid malabsorption, and that the intestinal transit time is related to steroid absorption even under physiologic conditions.
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PMID:Adaptation of cholesterol and bile acid metabolism and vitamin B12 absorption in the long-term follow-up after partial ileal bypass. 394 24

Cholesterol synthesis and its diurnal variation was studied by measuring squalene, free and esterified methyl sterols and cholesterol, and triglycerides in serum lipoproteins every four hours over a period of 24 hours in controls and in patients with jejunoileal bypass or ileal exclusion. Fat absorption, as indicated by postprandial increase of very-low-density lipoprotein (VLDL) lipids (including chylomicrons) and fecal fat, was markedly impaired in jejunoileal bypass. Fecal analysis indicated that bile acid malabsorption enhanced cholesterol synthesis about sixfold in ileal dysfunction, and twofold in jejunoileal bypass with moderate bile acid and cholesterol malabsorption. The squalene contents were not increased consistently in the VLDL and combined low-density plus high-density lipoproteins (LDL + HDL) of the two operated groups and, in contrast to the controls, the diurnal variation was inconsistent. The levels of unesterified methyl sterols, delta 8-dimethylsterol and delta 8-methostenol in particular, were several times higher throughout the 24 hour period in the lipoproteins of the two patient groups than of the controls, were higher in ileal dysfunction than jejunoileal bypass, exhibited a constant diurnal rhythm in the controls but only in the relatively small VLDL fraction (not in the large LDL + HDL) of the operated groups, and were positively correlated with cholesterol synthesis in the three groups combined (for methyl sterols in VLDL r = 0.740 and in LDL + HDL r = 0.869). Esterified methyl sterols were also increased in the operated groups but were not correlated with cholesterol synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cholesterol precursors and their diurnal rhythm in lipoproteins of patients with jejuno-ileal bypass and ileal dysfunction. 403 1

Young adult male rats were made hypercholesterolemic by feeding cholesterol (+ cholic acid). The effect of rye crispbread on hepatic and plasma cholesterol concentrations, hepatic cholesterol synthesis, small intestinal cell turnover and fecal output was investigated. Diets containing 50 and 75% rye crispbread (g dry wt) were compared with positive control diets of similar gross composition, in which the insoluble component of rye was matched with cellulose and the soluble component with guar gum. A negative control diet containing no non-starch polysaccharide was also included. Cholesterol supplementation was maintained in half the rats on each diet. Rye caused a marked increase in fecal output that was greater than that seen in the positive control groups. However, crypt cell proliferation in the small intestine was less than that seen in the high fiber control groups. Rye reduced total plasma cholesterol concentrations only in those rats that continued to receive the high cholesterol diet. However, whether or not cholesterol was fed, the presence of nonstarch polysaccharide caused a decrease in liver cholesterol concentrations. Rye caused a marked increase in hepatic cholesterol synthesis over both the positive controls and the rats fed a fiber-free diet. This implies that rye causes a loss of cholesterol from the body, probably due to malabsorption of bile acids and cholesterol.
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PMID:Baked rye products modify cholesterol metabolism and crypt cell proliferation rates in rats. 822 98

Hypercholesterolemia is an important atherogenic risk factor in type II diabetes, and although coronary artery disease (CAD) is frequent in these patients, it is not known whether cholesterol and lipoprotein metabolism differ in patients with (CAD+) and without CAD (CAD-). Our aim was to study cholesterol metabolism and lipoprotein kinetics in mildly hypercholesterolemic type II diabetic men with and without CAD under similar dietary conditions. Despite similar serum and lipoprotein cholesterol levels, and kinetics of total and dense LDL apo B, light and dense LDL particles were cholesterol-enriched only in CAD+ subjects. Apolipoprotein A-II level was lower in CAD+ than in CAD- subjects (27.1 +/- 0.7 versus 30.9 +/- 0.7 mg/dl, P < 0.05), HDL cholesterol and apolipoprotein A-I kinetics were similar in the two groups. Cholesterol absorption was significantly higher in the CAD+ versus CAD- subjects (27 +/- 2 versus 20 +/- 3%, P < 0.05). In multiple logistic stepwise regression analysis with CAD as the dependent variable, cholesterol absorption efficiency and serum plant sterol/cholesterol proportions were the only variables significantly associated with CAD. In conclusion, in mildly hypercholesterolemic type II diabetic patients, the only metabolic parameter differentiating CAD patients from non-CAD ones was significantly higher cholesterol absorption efficiency in the coronary patients, which could contribute to the finding of the atherogenic cholesterol-rich dense LDL subfraction in these patients. Thus, a treatment causing cholesterol malabsorption by sitostanol alone or in combination with statin could be beneficial in these patients.
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PMID:Cholesterol absorption and lipoprotein metabolism in type II diabetes mellitus with and without coronary artery disease. 890 58


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