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)

Male mongrel rabbits, divided into 5 groups (1) controls, (2) animals receiving a high-fat diet (HFD) containing cholesterol and coconut oil, (3) HFD + selenium, (4) HFD + vitamin E, (5) HFD + selenium + vitamin E, were treated for 12 weeks. In the groups receiving selenium and/or vitamin E, the elevation of serum total lipids, beta-lipoproteins, total cholesterol and triglyceride was markedly suppressed. HDL cholesterol in these groups of animals was increased. The cytochrome P-450 content in liver microsomes was increased, and the concentration of malondialdehyde in the blood plasma of rabbits was significantly decreased, while thyroid hormones (T4, T3), cortisol and insulin level were increased. Surface area of the lipid deposits at 12 weeks measured planimetrically averaged 76% in HFD-fed animals but only 28% in selenium + vitamin E treated rabbits. The important finding of this study is that combination of selenium and vitamin E, results in an intensified effect on the improvement of metabolic processes and on the reduction of atherosclerotic plaque formation.
Atherosclerosis 1991 Mar
PMID:Effect of selenium and vitamin E on the development of experimental atherosclerosis in rabbits. 167 Feb 89

Exposure of HepG2 and Hep3B cells to gemfibrozil (40 micrograms/ml), a hypolipidemic drug, resulted in a 2-fold induction of apo AI mRNA and, a one-third reduction in apo B mRNA but had no significant effect on apo E mRNA levels. The hypothesis that the mechanism of action of gemfibrozil involved the cytochrome P-450 system was tested by using ketoconazole, a P-450 inhibitor, which blocks the formation of endogenous polar sterols. When the cells were treated with ketoconazole at a concentration of greater than or equal to 15 microM, the levels of apo AI, and apo B mRNAs decreased by 50% and 35%, respectively, compared to the basal level. No significant effect on apo E mRNA level was observed during ketoconazole treatment. The effects of gemfibrozil and ketoconazole on various apolipoprotein secretion were studied using pulse-chase experiments. It was observed that the selective alterations in the rates of apo AI and apo B production were occurring at the level of synthesis. This observation is consistent with the findings indicating a strong direct correlation between hepatic apolipoprotein mRNA concentration and secreted apolipoprotein levels. The induction of apo AI mRNA by gemfibrozil was not apparent when the cells were simultaneously treated with ketoconazole. However, the level of apo B mRNA was reduced further to less than 55% of the control level suggesting that there might be an additive effect of these two drugs on apo B synthesis.
Atherosclerosis 1991 Nov
PMID:Effects of gemfibrozil and ketoconazole on human apolipoprotein AI, B and E levels in two hepatoma cell lines, HepG2 and Hep3B. 181 54

Arachidonic acid metabolism via cyclooxygenase, lipoxygenase, and cytochrome P-450 epoxygenase was investigated in thoracic aortic tissue obtained from rabbits fed either standard rabbit chow or chow containing 2% cholesterol. Aortic strips were incubated with [14C]arachidonic acid and A23187. Metabolites from extracted media were resolved by high-pressure liquid chromatography (HPLC). Normal and cholesterol-fed rabbit aortas synthesized prostaglandins (PGs) and hydroxyeicosatetraenoic acids (HETEs). The major cyclooxygenase products were 6-keto-PGF1 alpha and PGE2. Basal aortic 6-keto-PGF1 alpha production was slightly reduced in cholesterol-fed compared with normal rabbits. 12(S)- and 15(S)-HETE were the major aortic lipoxygenase products from both normal and cholesterol-fed rabbits. The structures were confirmed by gas chromatography-mass spectrometry (GC-MS). Only cholesterol-fed rabbit aortas metabolized arachidonic acid via cytochrome P-450 epoxygenase to the epoxyeicosatrienoic acids (EETs). 14,15-, 11,12-, 8,9-, and 5,6-EET were identified based on comigration on HPLC with known 14C-labeled standards and typical mass spectra. Incubation of normal aorta with 14,15-EET decreased the basal synthesis of 6-keto-PGF1 alpha. The other EETs were without effect. The four EET regioisomers relaxed the norepinephrine-precontracted normal and cholesterol-fed rabbit aorta. The relaxation response to 14,15-EET was greater in aortas from cholesterol-fed rabbits. These studies demonstrate that hypercholesterolemia, before the development of atherosclerosis, alters arachidonic acid metabolism via both the cyclooxygenase and epoxygenase pathways.
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PMID:Enhanced synthesis of epoxyeicosatrienoic acids by cholesterol-fed rabbit aorta. 188 29

Inbred mouse strains AKXL-38 and AKXL-38a are congenic strains that differ at the Ah locus, a gene which affects the inducibility of the cytochrome P-450 enzymes. The Ah-responsive strain, AKXL-38a, is more susceptible to 3-methylcholanthrene-induced tumors than the Ah-nonresponsive strain, AKXL-38. We previously reported that 3-methylcholanthrene (MC) increased the number and the size of atherosclerotic lesions in a dose-dependent fashion. We now demonstrate that the effect of MC is greater in Ah-responsive mice than in Ah-nonresponsive mice indicating that Ah-responsive mice not only are more susceptible to MC-induced cancer but also are more susceptible to MC-enhanced atherosclerosis. Mice that received atherogenic diet for 14 weeks but no MC had 1.3-1.4 lesions/mouse regardless of genetic type. When mice were treated with MC, the number of lesions increased to 2.1 +/- 0.1 (SE) in Ah-nonresponsive mice, 2.6 +/- 0.2 in Ah-responsive mice, and 2.3 +/- 0.2 in the F1 hybrid. The total area involved in lesions was 9.3-12.6 micron2 in untreated animals. When mice were treated with MC, the total lesion area increased to 23.5 +/- 5.2 micron2 in Ah-nonresponsive mice, to 43.9 +/- 6.6 micron2 in Ah-responsive mice, and to 36.2 +/- 4.8 micron2 in F1 hybrids. Thus MC increased the lesion area in both strains of mice, but the increase was significantly greater in Ah-responsive than in Ah-nonresponsive animals. High density lipoprotein levels were not significantly affected by MC treatment or Ah genotype. In order to determine whether the increased susceptibility to MC-induced atherosclerosis segregated with the Ah gene, AKXL-38 and AKXL-38a mice were mated and the F1 progeny were backcrossed to the Ah-nonresponsive parent. Backcross progeny were tested for Ah genotype by zoxazolamine sleeping time. Measurements of lesions showed that increased susceptibility to MC-enhanced atherosclerosis segregated with the Ah locus.
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PMID:Effect of 3-methylcholanthrene on atherosclerosis in two congenic strains of mice with different susceptibilities to methylcholanthrene-induced tumors. 370 65

Our previous studies have shown that the pollen extract, Cernitin, reveals lipid-lowering properties in animals and humans. The present study was designed to investigate the influence of Cernitin on the development of experimental atherosclerosis in rabbits over a period of 12 weeks. Forty male mongrel rabbits were divided into 4 equal groups: (1) controls, (2) animals receiving high-fat diet (HFD) containing cholesterol and coconut oil, (3) HFD + pollen extract, and (4) HFD + clofibrate. The most pronounced reduction in lipid metabolism and in the severity of plaque formation occurred after the pollen extract had been applied. The total cholesterol content in serum and liver homogenate was depressed by 67% and 45%, respectively, while the serum HDL cholesterol and alpha-lipoproteins level was increased by 19% and from 7.73% to 21.73% respectively. The cytochrome P-450 content in the liver microsomes was elevated by 98% (nmol/g liver). Atherosclerotic plaque intensity at 12 weeks, measured planimetrically, averaged 85.5% in HFD-fed animals vs 33.7% in pollen extract-treated rabbits. These findings suggest that Cernitin, in addition to significantly lowering serum lipid levels in rabbits on an experimental diet, may modify lipid deposition in major arteries.
Atherosclerosis 1986 Oct
PMID:Effect of pollen extract on the development of experimental atherosclerosis in rabbits. 377 73

Cytochrome P-450-dependent mixed function oxidase activity is present in vascular tissue; however, as far as we could determine, the distribution of monooxygenase activity across the blood vessel wall has not previously been assessed. The aryl-hydrocarbon hydroxylase activity was examined by metabolism of benzo[a]pyrene in microsomes prepared from intimal and smooth muscle cell scrapings of the hog thoracic aorta. Microsomes of intimal cells comprising 95% endothelial cells showed an approximately 2.5-fold increase in aryl-hydrocarbon hydroxylase activity compared with that in microsomes prepared from medial smooth muscle cells. Michaelis-Mentin kinetics for the intimal enzyme yielded an apparent Km value of 11.11 microM and an apparent Vmax of 3-OH benzo[a]pyrene of 40 pmol/mg protein/10 min. Aryl-hydrocarbon hydroxylase activity was dependent on nicotinamide adenine dinucleotide phosphate and was inhibited by 7,8 benzoflavone, SKF 525A, and carbon monoxide. The localization of cytochrome P-450-dependent mixed function oxidase primarily to the intimal surface of the aorta may indicate a role for this enzyme system in vasoregulation and the pathogenesis of atherosclerosis.
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PMID:Presence of cytochrome P-450-dependent monooxygenase in intimal cells of the hog aorta. 407 22

Arachidonic acid elicited relaxation responses in normal rabbit aorta precontracted with norepinephrine. The relaxation response was enhanced by the cyclooxygenase inhibitor indomethacin and inhibited by lipoxygenase inhibitors, including nordihydroguaiaretic acid and cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate. The cytochrome P-450 epoxygenase inhibitor metyrapone had no effect on arachidonic acid-induced relaxations. The present study hypothesized that a lipoxygenase metabolite of arachidonic acid mediated the response. Incubation of rabbit aorta with [14C]arachidonic acid resulted in the synthesis of a previously unidentified 14C-labeled metabolite and was called the unknown factor. Production of the unknown factor was not inhibited by indomethacin and decreased by lipoxygenase inhibitors. Production of the unknown factor and arachidonic acid-induced relaxations were dependent on an intact endothelium, indicating that the cellular source of the unknown relaxant factor was the endothelial cell. This was confirmed by demonstrating the ability of cultured rabbit aortic endothelial cells to produce the unknown factor from [14C]arachidonic acid. Feeding rabbits a 2% cholesterol diet for 2 wk induced hypercholesterolemia without causing atherosclerosis. In the cholesterol-fed rabbits, indomethacin enhanced arachidonic acid-induced relaxations in norepinephrine-precontracted aortas (maximal relaxation 49.0 +/- 2.5 vs. 35.5 +/- 1.7%, cholesterol-fed vs. normal) and increased production of the unknown factor compared with normal rabbits. The partially purified unknown factor elicited an approximately 26% inhibition of the vasoconstrictor response to norepinephrine in intact rabbit aorta. Further purification of the unknown factor by reverse-phase high-pressure liquid chromatography system resulted in isolation of a radioactive product that relaxed precontracted rabbit aorta. Therefore these data suggest that in normal and hypercholesterolemic rabbit aorta the endothelium produces an unknown metabolite of arachidonic acid that causes vasorelaxation and may regulate vascular tone.
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PMID:Vasorelaxation by an endothelium-derived metabolite of arachidonic acid. 878 Jan 99

Necropsy samples of atherosclerotic lesions of different histological stages have been analysed. Ceroid was present in all the lesions, within lipid-laden macrophage foam cells and extracellularly in the atheromatous core of advanced lesions. Mean levels of 7 beta-hydroxycholesterol, 26-hydroxycholesterol and hydroxyoctadecadienoic acids were all significantly greater in lesions than in normal intima. Levels of hydroxycholesterols were very low or undetectable in normal intima. Fatty streaks showed the highest ratio of 7 beta-hydroxycholesterol to cholesterol, and the lowest ratio of linoleate to oleate, suggesting that this type of lesion experiences the greatest free radical activity. Levels of 26-hydroxycholesterol, a product of the cytochrome P-450 enzyme sterol 26-hydroxylase, and the ratio of 26-hydroxycholesterol to cholesterol were significantly higher in advanced lesions than in intermediate lesions or fatty streaks. The ratio of alpha-tocopherol to cholesterol levels varied widely in normal intima but was consistently low in lesions, especially those rich in macrophage foam cells, suggesting that oxidative activity in the lesion may lead to significant oxidation of the lesion constituents only after alpha-tocopherol has been depleted. Macrophage death was a characteristic feature of advanced lesions, with apoptotic bodies present, and occasionally, intact apoptotic cells were seen in lesions. These striking correlations between macrophages, lipid oxidation, alpha-tocopherol depletion, ceroid accumulation, and macrophage death in advanced lesions, strongly support a role for oxidative damage in atherosclerosis, and lend credence to the idea that alpha-tocopherol dietary supplementation may slow the progression of atherosclerosis in humans.
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PMID:Macrophages, lipid oxidation, ceroid accumulation and alpha-tocopherol depletion in human atherosclerotic lesions. 882 21

Cholesterol regulates hepatic 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity by feedback inhibition. It has been suggested that oxidized derivatives of cholesterol (oxysterols) play an important role, as an intracellular mediator, in the feedback inhibition of cholesterol biosynthesis. We, therefore, investigated the role of intracellular oxysterols in the regulation of HMG-CoA reductase activity. Rats were fed with food (control), cholesterol, clofibrate as a potentiator of the microsomal monooxygenase cytochrome P-450 enzyme system, ketoconazole as a strong inhibitor of the system, or butylated hydroxytoluene (BHT) as an antioxidant. We analyzed and compared hepatic microsomal oxysterol levels among the groups. The results of this study indicated that the oxysterol level, especially 7beta-hydroxycholesterol and 7-ketocholestrol, in the liver was lowered by the administration of ketoconazole and BHT, and HMG-CoA reductase activity was increased in response to these agents. However, there was no change in the HMG-CoA reductase activity, after the administration of clofibrate. We conclude that reduced levels of oxysterol may release the inhibitory effect on the HMG-CoA reductase enzyme and lead to up-regulation of the enzyme.
Atherosclerosis 1997 Jun
PMID:Reduction of oxysterol levels up-regulates HMG-CoA reductase activity in rat liver. 919 77

The effects of ascorbic acid (AA) or vitamin C in atherosclerosis has attracted considerable attention; however results of clinical studies are conflicting. Several studies indicate an increase in plasma triglyceride (TG) and cholesterol (CH) levels in guinea pigs (GP) that have been fed a diet containing a minimal amount of AA. Previous studies carried out in GP fed a diet devoid of AA showed a significant decrease in cytochrome P-450 level compared to GP fed high and adequate amounts; however, the level of cytochrome P-450 in the two groups were not significantly different. The enzymes that synthesize TG and CH are located in endoplasmic reticulum which is also the site for cytochrome P-450 synthesis. It is of interest to determine whether there is an association between TG and CH synthesis and cytochrome P-450 induction. Adult male Hartley GP weighing 350-400 g were fed a diet containing 2.5% (Group I), 0.1% (Group II) and 0% (Group III) AA. The food consumption and weight gain were not significantly different in different groups. After feeding the diet for four weeks, half of the animals in each group were starved. Blood was withdrawn and TG and CH were determined in the serum. TG and CH were markedly elevated in both starved and nonstarved Group III GP; however, these levels were not altered in Group 1 and Group II GP. Plasma AA showed significant differences in all three nonstarved and starved groups. Plasma alpha-lipoprotein was decreased and beta-lipoprotein was increased in Group III GP. Hepatic CH and TG were also significantly elevated in Group III GP, and Groups I and II showed no changes. TG and CH showed a negative correlation with cytochrome P-450, whereas CH and TG showed a positive correlation. We conclude that AA deficiency causes extensive hyperlipidemia, feeding high level of AA does not alter the lipid metabolism and induction ofcytochrome P-450 is inversely related to TG and CH synthesis.
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PMID:Association between hyperlipidemia and hepatic cytochrome P-450 in guinea pigs. 934 27


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