Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatic, heparin-releaseable lipase is a multifunctional enzyme that may act on all lipoprotein classes present in plasma from fasted subjects. Recent evidence suggests that the enzyme also plays a role in the metabolism of chylomicronremnants. Its activity is impaired in normolipidemic patients with coronary heart disease, which also have a delayed removal of chylomicronremnants from plasma. Therefore hepatic lipase, in addition to lipoprotein lipase, plays an important role in postprandial lipoprotein metabolism. The activity levels of lecithin: cholesterol acyltransferase (LCAT) and cholesterylester transfer protein (CETP) are virtually unchanged after the ingestion of an oral fat load by normolipidemic subjects. However, the net mass transfer of cholesterylesters out of HDL into apo B-containing lipoproteins (chylomicronremnants, VLDL/IDL/LDL) is strongly increased. All triglyceride-rich lipoprotein fractions accumulate postprandially and, as a result of CETP action, become enriched in cholesterylesters. Defects in hepatic remnant removal may result in influx of remnants into the arterial wall. In patients with hyperlipidemia (and increased risk for atherosclerosis) the CETP-mediated formation of cholesterylester-rich remnants may operate, not only during the postprandial phase, but continuously.
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PMID:[Role of hepatic lipases, cholesterol ester transfer proteins and LCAT in the postprandial phase]. 208 75

The familial hypoalphalipoproteinemias are a heterogeneous group of rare lipoprotein disorders characterized by extremely low levels of plasma high density lipoproteins (HDL) and, in most cases, autosomal recessive inheritance. Most of these conditions present distinctive and diagnostic clinical and laboratory abnormalities. In spite of the marked reductions in HDL, however, many of these conditions are not associated with premature atherosclerosis. This is true of Tangier disease, Fish Eye disease, lecithin: cholesterol acyltransferase deficiency, and of some variants of apo Al. Another condition, defined as a primary and familial decrease in HDL-cholesterol levels in the absence of other lipoprotein abnormalities. that is associated with premature atherosclerosis was originally called Familial Hypoalphalipoproteinemia but is better referred as to Familial Isolated Hypoalphalipoproteinemia. At present, the prevalence, inheritance, and the underlying defect(s) in this disorder are unknown. Decreased or absent synthesis of apo A-I due to a gene defect is the cause of apo A-I/C-III and apo A-I/C-III/A-IV deficiency. However, the etiology of the low levels of HDL is unclear for most of the remaining familial hypoalphalipoproteinemias. Increased catabolism, decreased synthesis and altered equilibration of HDL between intra- and extravascular spaces have all been suggested as underlying causes of low plasma HDL. Whatever their causes, these disorders are associated with altered HDL composition and altered equilibration of cholesterol amongst the various lipoprotein classes. The absence of consistent correlation with premature atherosclerosis in many of these conditions suggests that the protective effect of HDL may reside in a quantitatively small, but metabolically active subfraction of HDL particles.
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PMID:Familial hypoalphalipoproteinemias. 211 26

Pressure on the outside of arteries can cause physical and biochemical changes in the vessel wall of rabbits which are characteristic of atherosclerosis. It is hypothesized that occlusion of the vasa vasorum causes ischaemia of the arterial media which results in smooth muscle cell proliferation and cellular accumulation of cholesteryl esters. Hypoxia increases mRNA for platelet-derived growth factor in arterial wall cells and increases the activity of acyl CoA: cholesterol acyltransferase (ACAT). Such a mechanism may explain many of the anatomical, actuarial and environmental risk factors for atherosclerosis. Hyperfusion of the vasa vasorum may follow thrombosis.
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PMID:Arterial wall hypoxia following hyperfusion through the vasa vasorum is an initial lesion in atherosclerosis. 212 48

The regulation of aortic ACAT by a cholesterol substrate pool (CSP) was investigated in a rabbit progression/regression model of dietary-induced atherosclerosis. ACAT activity increased 25-fold during the 10-week progression phase of the study. ACAT activity decreased 8-fold during the 24-week regression phase of the study, however, it was still 14-fold greater than in normal aortas. ACAT activity assayed in the absence vs. the presence of exogenous cholesterol was used as a qualitative measure of the amount of cholesterol in the CSP. The CSP was filled to 28% of capacity in normal aortas, this increased to 75% during the progression phase. By the end of the regression phase, the CSP was filled to 100% of capacity even though serum cholesterol levels had returned to normal. The data are discussed in terms of emerging concepts of intracellular cholesterol trafficking, ACAT inhibitors, and the types of atherosclerotic lesions which may be subject to amelioration by ACAT inhibitors.
Atherosclerosis 1990 Aug
PMID:Regulation of ACAT activity by a cholesterol substrate pool during the progression and regression phases of atherosclerosis: implications for drug discovery. 224 95

CL 277,082 is an inhibitor of acyl-CoA: cholesterol acyltransferase (ACAT). The effects of this drug on lipoprotein metabolism have been examined in cholesterol-fed rats. An optimal dose of drug incorporated into the diet (0.1% w/w) for 7 days reduced plasma cholesterol by 48% and plasma triglycerides by 72%. The decrease in plasma cholesterol was due to a reduction in triglyceride-rich lipoproteins and in HDL cholesterol. There was a significant 72% reduction in intestinal ACAT activity, accompanied by a 41% reduction in hepatic cholesterol content. There was a smaller 21% reduction in hepatic ACAT activity. Hepatic HMG-CoA reductase activity increased 3-fold. HDL binding activity by liver membranes was not altered significantly. The decrease in plasma cholesterol with this ACAT inhibitor is most likely due to decreased absorption of dietary cholesterol resulting from inhibition of intestinal ACAT.
Atherosclerosis 1990 May
PMID:On the mechanism by which an ACAT inhibitor (CL 277,082) influences plasma lipoproteins in the rat. 236 Sep 13

We have previously described a colony of New Zealand White rabbits that are resistant to hypercholesterolemia when fed a cholesterol-enriched diet. The present studies used skin fibroblasts obtained from normal and hypercholesterolemia-resistant rabbits to investigate cholesterol metabolism and lipid composition in vitro. The lipid compositions of the two cell lines after incubation in either fetal calf serum or lipoprotein-deficient serum were similar. The conversion of radiolabeled acetate into sterol and phospholipids was higher in resistant fibroblasts than in normal fibroblasts. In contrast, incorporation of radiolabeled oleic acid into cholesteryl ester was significantly lower in resistant fibroblasts than in normal cells. In parallel experiments, the 3-hydroxy-3-methylglutaryl coenzyme A reductase activity was higher and acyl-coenzyme A:cholesterol acyltransferase activity was lower in resistant cells compared to normal cells. Furthermore, binding, uptake, and degradation of normal rabbit 125I-labeled LDL (low density lipoproteins) were 30% higher in resistant than in normal fibroblasts. These observations are consistent with results from previous studies of cholesterol metabolism in the liver membranes of these rabbits. The results indicate that extrahepatic cells (such as fibroblasts) from the resistant rabbit exhibit the same altered cholesterol metabolism as that found in the hepatic tissues of these rabbits. These studies suggest that the resistant rabbit may provide an in vivo and in vitro system for studying the mechanisms by which some individuals of a species can minimize the effect of dietary cholesterol on the development of hypercholesterolemia and atherosclerosis.
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PMID:Cholesterol metabolism in fibroblasts from rabbits resistant to diet-induced hypercholesterolemia. 237 66

Various antihypertensive agents were studied in vitro to determine their effects on cholesterol esterification by arterial ACAT (acylCoA:cholesterol acyltransferase; E.C. 2.3.1.26) and on the activity of plasma LCAT (lecithin:cholesterol acyltransferase; E.C. 2.3.1.43). Propranolol inhibited ACAT in normal rat aorta, atheromatous rabbit aorta, and in isolated microsomes from atheromatous rabbit aorta, and in isolated microsomes from atheromatous rabbit aorta. Inhibition reached 50% in microsomes at approximately 0.8 mM. Metoprolol, prazosin, and chlorthalidone also inhibited microsomal ACAT, but to a lesser extent than propranolol; nadolol had no effect on the enzyme. Propranolol, metoprolol, prazosin, and chlorthalidone also inhibited LCAT in human plasma, whereas nadolol showed no inhibitory effect. Fifty percent inhibition occurred at 2 mM with prazosin and chlorthalidone and at 4-5 mM with propranolol. Metoprolol showed a weak dose-dependent inhibition that ranged from 2 to 10% over the concentration range 0.5-5 mM. The data suggest a mechanistic basis for altered lipoprotein profiles observed clinically with certain antihypertensive therapies and suggest that a direct effect of beta-blockers on arterial wall metabolism may account for their recognized ability to reduce the development of experimental atherosclerosis and to improve survival in post-myocardial infarction patients.
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PMID:Effects of antihypertensive agents propranolol, metoprolol, nadolol, prazosin, and chlorthalidone on ACAT activity in rabbit and rat aortas and on LCAT activity in human plasma in vitro. 241 Jun 71

The association between serum lecithin: cholesterol acyltransferase (LCAT) activity and demographic and environmental factors, and the correlation of LCAT activity with serum lipids and lipoproteins were studied in a representative series of 1071 9-24-year-old subjects from East and West Finland. LCAT activity was determined by a method involving the use of exogenous substrate. Males had higher LCAT activity than females and subjects from East Finland had significantly higher activity than those from West Finland. LCAT activity tended to be lowest shortly after puberty. Women using oral contraceptives had significantly lower LCAT activity than women not using them. Serum LCAT activity was not associated with body mass index, physical activity index or smoking. Serum LCAT activity correlated positively with most serum lipid and lipoprotein variables. The highest correlation coefficients were found between LCAT activity and total cholesterol. LCAT activity correlated positively with the change in serum total cholesterol which had occurred during the preceding 3 and 6 years in men. Our results suggest that sex hormonal factors are associated with serum LCAT activity. The results are also in accordance with the idea that activity of LCAT increases in response to enhanced demands for cholesterol esterification in plasma.
Atherosclerosis 1989 May
PMID:Lecithin: cholesterol acyltransferase activity in children and young adults. 271 65

Activity of lecithine-cholesterol acyltransferase (LCAT) was studied in blood of 26 patients with atherosclerosis of various localization after course of treatment involving three-fold hemosorption. The initial activity of the enzyme, decreased distinctly as compared with normal state, was dissimilarly altered during hemosorption. The system LCAT-HDLP was stabilized after the third hemosorption. These results relevant to programming hemosorption therapy of patients with atherosclerosis.
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PMID:[The effect of hemosorption repeated three times on activity of lecithin cholesterol acyltransferase]. 274 6

The effects of 5 micrograms/ml of 25-hydroxycholesterol; cholestane-3 beta,5 alpha,6 beta-triol; and cholesterol on acyl CoA cholesterol acyltransferase, acid cholesteryl ester hydrolase and neutral cholesteryl ester hydrolase was studied in cultured rabbit aortic smooth muscle cells. After 1 hour incubation, 25-hydroxycholesterol resulted in a fourfold stimulation of acyl CoA cholesterol acyltransferase activity. No stimulation by 25-hydroxycholesterol was noted before 15 minutes or after 5 hours of incubation. Neither cholestane-3 beta,5 alpha,6 beta-triol nor cholesterol influenced acyl CoA cholesterol acyltransferase activity at any time interval. No significant effects of any of the sterols were noted on acid cholesteryl ester hydrolase or neutral cholesteryl ester hydrolase activity. The imbalance between acyl CoA cholesterol acyl transferase and hydrolase activities induced by 25-hydroxycholesterol could result in cholesteryl ester accumulation by arterial smooth muscle cells, which may be associated with atherosclerosis.
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PMID:Effects of cholesterol oxidation derivatives on cholesterol esterifying and cholesteryl ester hydrolytic enzyme activity of cultured rabbit aortic smooth muscle cells. 276 54


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