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)

Cholestyramine was administered to hamsters at 6 doses in the diet for 1 week. Plasma cholesterol, LDL + VLDL cholesterol and HDL cholesterol were measured after this period. Bile acid excretion was measured in faeces collected over the final 24 h of the experiment. A dose-response curve for each parameter measured was constructed using data from individual hamsters. For the bile acid and the cholesterol measurements a maximum response was observed at the highest doses. A correlation between the bile acids excreted over 24 h and the LDL + VLDL cholesterol showed that the maximum effect of cholestyramine on lowering plasma and lipoprotein cholesterol occurred at a submaximal excretion level of bile acids. Comparison of the efficiency of cholestyramine in reducing plasma cholesterol in the hamster with limited data in the dog and in man suggest that a greater lowering of plasma cholesterol is achieved in the dog and in man for an equivalent increase in bile acid excretion caused by the sequestrant. As is already known, cholestyramine treatment caused an increase in hepatic cholesterol 7 alpha-hydroxylase and HMG-CoA reductase activity. Interestingly in this study the novel observation was made that the bile acid sequestrant reduced the activity of hepatic acyl-CoA: cholesterol acyltransferase.
Atherosclerosis 1991 Aug
PMID:Cholesterol lowering and bile acid excretion in the hamster with cholestyramine treatment. 179 46

Regulation of expression of the genes for the low density lipoprotein receptor (LDLR) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) is of central importance in the control of cholesterol metabolism and thus in influencing the concentration of low density lipoprotein in the plasma. This can be studied by investigating the effects of factors (hormones, drugs, etc.) on the levels of mRNA for these genes. An RNase protection assay is reported for measurement of the levels of mRNA for the LDLR and HMGR. Several probes have been developed for these genes, together with probes for the "housekeeping" genes, beta-actin and glyceraldehyde-3-phosphate dehydrogenase. Various conditions in the assay have been examined and optimised, e.g. conditions for solution hybridization and RNase digestion and the use of "sense" RNA standards. The assay allows accurate measurement of approximately 2 x 10(7) copies of LDLR and HMGR mRNAs, which is equivalent to the number of copies present in approximately 1 x 10(6) human dermal fibroblasts and approximately 5 x 10(5) Hep G2 liver hepatoma cells cultured in 10% fetal calf serum. The average number of copies of mRNA per cell was estimated in fibroblasts and Hep G2 cells under various conditions of regulation of the LDLR and revealed the following: [table: see text] Under the chosen conditions 10 copies per cell was the detection limit for the assay. The effect of these treatments on the number of copies of mRNA per cell for beta-actin and glyceraldehyde-3-phosphate dehydrogenase was also determined.
Atherosclerosis 1991 Sep
PMID:A sensitive RNase protection assay for the quantitation of the mRNAs for the LDL receptor and HMG-CoA reductase in human total RNA. Effects of treatments on cells in culture designed to up- and down-regulate expression of the LDL receptor. 182 10

Restenosis after coronary angioplasty is due to a proliferation of smooth muscle cells growing in the vascular lumen, beneath the residual fragments of the atherosclerotic plaque, as seen in necropsy studies and examination of the specimens removed by atherectomy. At the histological analysis thrombi or their fibrocellular organization are not usually detectable. Smooth muscle cell proliferation leading to restenosis is very similar to the one observed in the experimental models of response-to-injury, so that these models are used to investigate into the pathogenetic mechanisms of restenosis. The main stimulus to the loss of the contractile phenotype and to the start of the smooth muscle cell proliferation is represented by the growth factors delivered by platelets adhered to the disendothelialized wall and by the smooth muscle cells themselves, stretched during the dilatation. Other stimuli can be growth factors delivered by monocytes and fibroblasts, by thrombin, endothelin, angiotensin and interleukin 1. The elastic recoil of the vessel wall, the plaque debris and the regional wall shear stress can also contribute to restenosis. The restenosis tissue is different from the atheromatous plaque in that it is almost only constituted by smooth muscle cells and intercellular matrix, while atheroma is much more complex due to the presence of various kinds of cells, of necrotic debris and lipid substances. The smooth muscle cells proliferation also contributes to the pathogenesis of atherosclerosis, but the stimuli starting this process have not been clarified yet; moreover this process is much slower than restenosis, interacting with several factors. Encouraging results have been achieved in the prevention of restenosis after angioplasty in experimental models, but not in man. In order to reduce the incidence of restenosis one should improve the results of angioplasty, even by the use of atherectomy and intracoronary stents. Among pharmacologic approaches anticoagulants, heparin, antiplatelet agents, calcium-channel blockers, corticosteroids all proved ineffective. Studies are in progress evaluating the effect of inhibitors of platelet-derived growth factor (PDGF), antitumor agents and radiation therapy, hirudin, angiotensin-converting enzyme inhibitors and HMG-CoA reductase inhibitors.
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PMID:[Restenosis after coronary angioplasty: its pathogenesis and prevention]. 184 86

We studied the effect of fluvastatin (XU 62-320), a new HMG-CoA reductase inhibitor, on the distribution of low density lipoprotein (LDL) subspecies and composition in humans. As expected, fluvastatin significantly lowered serum LDL levels (25% after 6 weeks of therapy). In addition, treatment with fluvastatin changed the LDL subspecies. In the group treated with fluvastatin, 38.5% of the individuals showed changes in the shape of LDL absorbance profile obtained from density gradient ultracentrifugation and 54% of the group showed changes in the electrophoretic mobility of the LDL bands. Of those showing changes in electrophoretic mobility, the majority (78%) shifted to slightly larger, less dense LDL after drug therapy. However, the LDL-cholesterol/apo B ratio changes were relatively small in all fluvastatin-treated individuals including the group with changes in electrophoretic mobility, confirming that HMG-CoA reductase inhibitor causes relatively small and subtle changes in the distribution of LDL subspecies.
Atherosclerosis 1991 Apr
PMID:Effects of fluvastatin (XU 62-320), an HMG-CoA reductase inhibitor, on the distribution and composition of low density lipoprotein subspecies in humans. 185 61

Normal rabbits typically respond to a diet high in cholesterol with a large increase in the concentration of plasma cholesterol. We have previously described the breeding and partial characterization of a variant rabbit which does not respond to a high cholesterol diet with changes in plasma cholesterol concentration. In the present report we have characterized three components involved in cholesterol homeostasis: the B/E (LDL) receptor, 3-hydroxy-3-methylglutaryl coenzyme A reductase activity (HMG-CoA reductase, EC 1.1.1.34) and acyl-coenzyme A: cholesterol acyltransferase activity (ACAT, EC 2.3.1.26) in the livers of the hypercholesterolemia-resistant rabbits. Using normal cholesterol-fed rabbit [125I] beta-VLDL as a ligand, liver membranes prepared from resistant rabbits fed a low-cholesterol diet had 70% higher binding capacity than membranes from normal rabbits fed the same diet. Similar experiments demonstrated that the resistant rabbits had a 240% higher B/E receptor binding capacity compared to normal animals when liver membranes were prepared from animals fed a 0.25% cholesterol-enriched diet. No difference in the binding affinity of [125I]beta-VLDL was detected in membranes prepared from normal or resistant animals. When fed a low-cholesterol diet, the resistant rabbits had approximately 2-fold higher hepatic HMG-CoA reductase activity (97.4 +/- 3.5 pmol product/mg/min in resistant animals compared to 45 +/- 1.1 pmol product/min/mg in normal animals). The difference was exaggerated in animals fed the 0.25% cholesterol-enriched diet, 73.3 +/- 5.5 vs 2.4 +/- 0.56 pmol product/min/mg for resistant and normal membranes respectively. The basal activity of ACAT in hepatic membranes was significantly lower in the resistant rabbits compared to normal rabbits (138 +/- 11 vs 268 +/- 19 pmol cholesteryl ester/min/mg in resistant and normal rabbits respectively); when fed a 0.25% cholesterol-enriched diet, the enzyme was induced 6-fold in normal animals but was increased only 2-fold in the resistant animal. These biochemical data suggested that the resistant rabbit maintained low intracellular cholesterol even when fed a cholesterol-enriched diet. Direct measurement of cellular cholesterol and cholesteryl esters demonstrated that the concentration of these lipids was significantly lower in the resistant animal than in normal animals with the largest differences found in the cytoplasmic rather than the membrane compartment. These studies demonstrate that the resistant rabbit manifests several quantitative differences in cholesterol metabolism and in the regulation of cholesterol metabolism; but these studies do not directly explain the underlying cause of the resistance to hypercholesterolemia in the resistant rabbit.
Atherosclerosis 1991 Apr
PMID:Cholesterol metabolism in hypercholesterolemia-resistant rabbits. 185 63

HMG-CoA reductase inhibitors have been proven effective in decreasing the plasma cholesterol levels in patients affected with various forms of hypercholesterolemia, familial dysbetalipoproteinemia, familial combined hyperlipidemia and in nephrotic and diabetic dyslipidemia. The purpose of this study was to monitor and evaluate the efficiency and safety of the therapy with simvastatin, an HMG-CoA reductase inhibitor, in a group of patients treated by continuous ambulatory peritoneal dialysis (CAPD) with severe hypercholesterolemia. Monitoring of the changes occurring in the various lipids and apolipoproteins in these patients included the measurements of the plasma lipids and apolipoproteins A-I, A-II, B, C-II, A-IV and Lp(a). Lipoproteins were separated by gel filtration, on a Superose 6HR column, before and after 24 weeks of treatment. The patterns were compared to those observed in a group of primary hyperlipidemic patients treated with Lovastatin, a compound of the same class. The drug was well tolerated by the CAPD patients and no adverse reaction was observed. In addition to the decrease of the total and LDL cholesterol, similar to that reported in other groups of patients, we further observed a decrease of the apo E concentration in both the CAPD and the hyperlipidemic patients. This decrease was especially pronounced in the HDLE fraction and could involve an upregulation of the apo B-E and/or apo E receptor. These results should provide information about the mechanism of action of this drug in patients with end-stage renal disease.
Atherosclerosis 1991 Feb
PMID:Effect of simvastatin treatment on the dyslipoproteinemia in CAPD patients. 187 12

Diabetes mellitus is associated with hyperlipidemia and increased risk of atherosclerosis. A diabetic animal model has been developed to study the effect of treatment with pravastatin, a potent HMG CoA reductase inhibitor, on plasma lipoprotein levels. Hypercholesterolemia was induced in alloxan diabetic and control rabbits by feeding a diet containing 25% casein and 10% hydrogenated coconut oil for 8 weeks. Feeding the casein-coconut oil diet to the diabetic group resulted in a 5-fold increase in serum cholesterol levels, which was not statistically different from the nondiabetic group fed this diet. However, in the diabetic group, there was more cholesterol in the VLDL fraction and less in LDL as compared to the nondiabetic group. Serum triacylglycerol levels in the diabetic rabbits were variable and ranged from 58-943 mg/dl. The diabetic and nondiabetic animals were then treated with pravastatin at a dose of 10 mg/kg per day for 21 days. In the nondiabetic group, pravastatin treatment significantly lowered serum and LDL cholesterol concentrations by 28.5% (52.3 mg/dl, P less than 0.05) and 36.2% (40.7 mg/dl, P less than 0.05) respectively, relative to the placebo group. Serum and VLDL triacylglycerol levels in the nondiabetic group were also significantly decreased following pravastatin treatment. In the diabetic group, serum and LDL cholesterol levels were decreased by 37.0% (69.1 mg/dl, P less than 0.05) and 52.7% (32.1 mg/dl, P less than 0.01), respectively, relative to the diabetics given the placebo. Pravastatin treatment did not adversely affect serum glucose levels. Thus, pravastatin treatment was effective in controlling the hypercholesterolemia present in these diabetic animals.
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PMID:The effect of pravastatin on serum cholesterol levels in hypercholesterolemic diabetic rabbits. 190 19

Rats administered estrogen-progestin formulation (0.667 mg of synthetic progestin and 0.067 mg of synthetic estrogen/kg body wt) showed increased hepatic cholesterogenesis, as evidenced by an increased activity of HMG-CoA reductase and increased incorporation of labelled acetate into liver cholesterol. Hepatic degradation of cholesterol to bile acids, however, was decreased. There was increased release of lipoproteins into the circulation but their clearance from the circulation was lower as revealed by a decreased activity of lipoprotein lipase of the extrahepatic tissues. Activity of plasma LCAT, which is involved in the transport of cholesterol from the tissues, was also decreased. The increase in serum and aortic cholesterol levels, increase in LDL cholesterol and decrease in HDL cholesterol in rats administered estrogen-progestin formulation suggest that prolonged administration of this formulation may predispose towards atherosclerosis.
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PMID:Mechanism of hyperlipidemia produced by estrogen-progestin formulation. 207 Nov 84

The HMG CoA reductase inhibitors are the most effective drugs for treating hypercholesterolaemia currently available. They inhibit cholesterol synthesis and thus stimulate receptor-mediated uptake and degradation of low-density lipoprotein cholesterol by the liver. In 30 patients with severe hypercholesterolaemia administration of lovastatin alone or in combination with other lipid-lowering manoeuvres maintained reductions of 25 to 31 per cent in serum cholesterol over five years. The drug was easy to take and well tolerated, the only significant side effect being a reversible myopathy. Two similar compounds, simvastatin and pravastatin, exert comparable effects on serum lipids, including modest reductions in triglycerides and increases in high-density lipoprotein cholesterol. The use of these drugs seems likely to exert a beneficial effect on atherosclerosis.
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PMID:HMG CoA reductase inhibitors as lipid-lowering agents: five years experience with lovastatin and an appraisal of simvastatin and pravastatin. 211 17

We investigated the possibility that established atherosclerosis and xanthomas in mature WHHL rabbits could be suppressed or even regressed when their serum cholesterol levels were kept extremely low. Ten-month-old WHHL rabbits were divided into 3 groups, i.e. control rabbits, sacrificed at age 10 months, and placebo and treated rabbits, sacrificed at age 18 months. The treated rabbits were given pravastatin sodium (50 mg/kg/day), an HMG-CoA reductase inhibitor, in combination with cholestyramine (2% in diet), a bile acid sequestrant, for 36 weeks. The serum cholesterol levels and atherogenic lipoproteins in the treated group were markedly reduced, by about 60% (P less than 0.005 and P less than 0.001). Consequently, the degrees of both coronary and aortic atherosclerosis in the treated group were significantly reduced compared with the placebo group, and were almost the same as in the control group. The histopathological findings supported the above results. In addition, the incidence and degree of xanthomas in digital joints in the treated group were significantly reduced. These results suggest that established atherosclerosis and xanthomas in mature WHHL rabbits could be suppressed by keeping their serum cholesterol levels extremely low by the combination drug treatment.
Atherosclerosis 1990 Jul
PMID:Suppression of established atherosclerosis and xanthomas in mature WHHL rabbits by keeping their serum cholesterol levels extremely low. Effect of pravastatin sodium in combination with cholestyramine. 211 30


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