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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synthesis of free radicals might play a role in the cellular process of atherosclerosis. This process can be stopped by antioxidants such as beta-carotene, vitamin C, or vitamin E, which will inactivate the effects of free radicals. Although antioxidant vitamins have not been proven to prevent cardiovascular diseases through the modulation of lipid peroxidation, it has been suggested that peroxidation might be a pathway to such prevention, mediated through the effects of antioxidants on blood pressure (BP) and arterial stiffness. Several observational epidemiologic studies and some clinical trials have suggested an inverse association between dietary intake of fruits and vegetables, and BP. An inverse link between serum levels of vitamin C and BP has also been determined in observational epidemiologic settings. Some relations between other antioxidant vitamins (retinol and beta-carotene) and BP are reported; they confer the same inverse association. However, results from clinical trials testing the effect of a single, or a combination of antioxidants at high pharmacologic doses have revealed inconsistent BP findings. So far, no evidence confirms that oral antioxidant supplementation is effective in preventing or treating high BP. Additional large studies should be conducted to determine the effect on BP of antioxidant supplementation at nutritional doses.
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PMID:Antioxidant vitamins and blood pressure. 1497 86

We have investigated the effect of standard doses of two fibrates, gemfibrozil and fenofibrate, on fasting and postprandial remnant-like particles (RLP) in subjects with combined hyperlipidemia. Forty-eight subjects participated; of these, 14 underwent a Vitamin A-fat loading test before and after 6 months of treatment with gemfibrozil (n = 8) and fenofibrate (n = 6). Blood was drawn every 2h for 12h after the test meal. The postprandial response was calculated as the area under the curve (AUC). There was no difference in fasting levels and pre-treatment AUC for triglycerides (TG), RLP cholesterol (RLP-C), RLP triglycerides (RLP-TG) and retinyl palmitate (RetP) between the two treatment groups. There was also no difference in the treatment effect on all parameters between the two treatment groups. Combining the two treatment groups, treatment resulted in a significant reduction in fasting levels and AUC of all four parameters. Assigning the difference observed between pre-treatment AUC of the combined study group and AUC of a normolipidemic (NL) control group as 100%, fibrate treatment resulted in decreases in AUC for TG, RLP-C, RLP-TG and RetP of 68, 69, 69 and 94%, respectively. These results indicate that fibrates are effective agents in reducing the postprandial increase in remnant lipoprotein particles.
Atherosclerosis 2004 Feb
PMID:Effect of fibrates on postprandial remnant-like particles in patients with combined hyperlipidemia. 1501 49

The -514C/T polymorphism located in the promoter region of the hepatic lipase gene mediates changes in the plasma levels of the enzyme. The aim of this study was to determine whether the presence of this polymorphism modifies the postprandial clearance of lipoproteins of intestinal origin. 51 normolipemic volunteers, homozygotes for the allele E3 of the apo E were selected (26 homozygotes for the C allele and 25 carriers of the T allele in both homozygote and heterozygote form). The subjects underwent a Vitamin A fat-loading test. Blood was drawn every hour until the 6th hour and every 2 h and 30 min until the 11th hour to determine cholesterol and plasma triglycerides as well as cholesterol, triglycerides (TG) and retinyl palmitate in triacylglycerol-rich lipoproteins (chylomicrons and chylomicron remnants). Carriers of the T allele showed significantly lower postprandial levels of apolipoprotein B (P < 0.01), total TG in plasma (P < 0.05), small TRL-TG (P < 0.04), large TRL-TG (P < 0.04) and small TRL-cholesterol (P < 0.04) when compared to subjects homozygous for the C allele. Our data suggest that the T allele of the -514C/T polymorphism in the promoter region of the hepatic lipase gene is associated with a lower postprandial lipemic response.
Atherosclerosis 2004 May
PMID:Influence of the -514C/T polymorphism in the promoter of the hepatic lipase gene on postprandial lipoprotein metabolism. 1513 53

Flavonoids are ingested with vegetables and beverages and exert a beneficial effect on cardiovascular disease. Studies in animals in vitro and in humans ex vivo on the resistance of lipoproteins to oxidation are not consistent and the mechanisms by which flavonoids protect against atherosclerosis are a matter of debate. In the present study, we investigated the effects of administering diets containing 0.3% (wt/wt) quercetin, 0.3% (wt/wt) catechin, or 35% (vol/wt) dealcoholated red wine (DRW) for 10 days in healthy rats on markers of oxidative damage in lipoproteins and in plasma. The antioxidant levels in low-density lipoproteins (LDL) or the lag phase, oxidation rate, and maximum level of conjugated dienes during ex vivo LDL oxidation did not differ between control and treated rats. Plasma levels of alpha-tocopherol and retinol were similar in all groups. The total antioxidant status of the plasma from rats fed either quercetin or DRW diet was higher than in control rats. Only glucuronide and sulfate compounds of quercetin were detected in plasma from rats fed the quercetin-rich diet, and no flavonoids or their metabolites were detected in plasma or LDL from rats fed the catechin- or the DRW-rich diet. No significant differences in malondialdehyde or in conjugated dienes in plasma were observed. These results indicate that although metabolites from quercetin are present in plasma, they are not detected in lipoproteins and do not modify the level of other antioxidants. In conclusion, in the absence of any pathology or of oxidative stress the intake of quercetin, catechin, or DRW did not protect lipoproteins from oxidation ex vivo.
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PMID:Flavonoid metabolites and susceptibility of rat lipoproteins to oxidation. 1530 78

Postprandial hyperlipidemia has been linked to premature coronary artery disease (CAD) in fasting normotriglyceridemic patients. We investigated the effects of increasing doses of simvastatin up to 80 mg/day on fasting and postprandial lipoprotein metabolism in 18 normotriglyceridemic patients with premature CAD. Fasting lipoprotein subfractions and cholesteryl ester transfer protein (CETP) activity were determined after each 5-week dose titration (0, 20, 40 and 80 mg/day). At baseline and after treatment with simvastatin 80 mg/day, standardised Vitamin A oral fat loading tests (50 g/m2; 10 h) were carried out. Ten normolipidemic healthy control subjects matched for gender, age and BMI underwent tests without medication. Treatment with simvastatin resulted in dose-dependent reductions of fasting LDL-cholesterol, without changing cholesterol levels in the VLDL-1, VLDL-2 and IDL fractions. In addition, simvastatin decreased CETP activity dose-dependently, although HDL-cholesterol remained unchanged. Simvastatin 80 mg/day decreased fasting plasma triglycerides (TG) by 26% (P < 0.05), but did not decrease significantly TG levels in any of the subfractions. The TG/cholesterol ratio increased in all subfractions. The plasma TG response to the oral fat loading test, estimated as area under the curve (TG-AUC), improved by 30% (from 21.5 +/- 2.5 to 15.1 +/- 1.9 mmol h/L; P < 0.01). Treatment with simvastatin 80 mg/day improved chylomicron remnant clearance (RE-AUC) by 36% from 30.0 +/- 2.6 to 19.2 +/- 3.3 mg h/L (P < 0.01). After therapy, remnant clearance in patients was similar to controls (19.2 +/- 3.3 and 20.3 +/- 2.7 mg h/L, respectively), suggesting a normalization of this potentially atherogenic process. In conclusion, high-dose simvastatin has beneficial effects in normotriglyceridemic patients with premature CAD, due to improved chylomicron remnant clearance, besides effective lowering of LDL-cholesterol. In addition, the lipoprotein subfractions became more cholesterol-poor, as reflected by the increased TG/cholesterol ratio, which potentially makes them less atherogenic.
Atherosclerosis 2005 Jan
PMID:Effects of increasing doses of simvastatin on fasting lipoprotein subfractions, and the effect of high-dose simvastatin on postprandial chylomicron remnant clearance in normotriglyceridemic patients with premature coronary sclerosis. 1558 12

Oxidative stress has been suggested as one of the physiopathologic conditions underlying the association of total plasma homocysteine (p-tHcy) with cardiovascular disease (CVD), but this hypothesis has not been validated in human epidemiological studies. We measured plasma and erythrocyte antioxidant enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD), along with serum lipid-soluble antioxidants alpha-tocopherol, beta-carotene, lycopene and retinol, in a sample of 123 healthy elderly subjects (54 men, 69 women). Plasma malondialdehyde (p-MDA) was determined as a marker of lipid peroxidation, and p-tHcy was quantified by HPLC. No significant differences were found for p-MDA, GPx or SOD activities or serum antioxidant concentrations, in subjects with elevated p-tHcy (> or =15 micromol/l) as compared to those with lower plasma homocysteine. Hyperhomocysteinemia did not lead to increased risk of having the highest p-MDA values, in either sex. We found no evidence that p-tHcy was associated with lipid peroxidation in this elderly human sample. Our results do not support the view that hyperhomocysteinemia would induce an adaptive response of antioxidant systems, either. More epidemiologic and clinical research is needed to clarify whether homocysteine promotes atherosclerosis by means of an oxidative stress mechanism.
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PMID:No evidence for oxidative stress as a mechanism of action of hyperhomocysteinemia in humans. 1562 99

Today one of the leading theories in the concept of atherogenesis underlines the key role of oxidized low-density lipoproteins (LDL). This paper describes new original and easy-to-use biochemical methods for evaluating the oxidative-antioxidative potential (LDL resistance to oxidation in vitro and the LDL level of alpha-tocopherol and retinol), as well as the results of their development and testing in 2 groups (62 patients with coronary atherosclerosis and 95 healthy individuals). LDL were isolated from their sera via precipitation with heparin and MnCl2. The precipitated LDL were washed in 0.9% NaCl solution and dissolved in 1 M NaCl solution. For evaluation of the resistance of LDL to oxidation in vitro, the precipitated LDL were incubated at 37 degrees C with 50 microM of copper ions; before and 0.5 h, 1.0 h, and 2.0 h after LDL incubation, TBARS products were determined by the fluorimetric technique after Schun J. et al. (1978). For evaluation of the antioxidative potntial of LDL, the concentrations of alpha-tocopheral and retinol in the precipitated LDL were measured by using the fluorimetric technique described by Taylor S. L. et al. (1976). The new methods were found to be highly reproducible. There was a high positive correlation (r = +0.98 +/- 0.04, p < 0.001) between the oxidative resistance of the LDL isolated from sera by ultracentrifugation and that of the precipitated LDL. There was also a high positive correlation (r = +0.79 +/- 0.09, p < 0.01) between the alpha-tocopherol and retinol levels determined by the fluorimetric technique and the LDL levels measured by the authors' method. The new methods were clinically tested with success. The significantly elevated baseline level of lipid perioxidation products in the precipitated LDL, the low oxidative resistance of the precipitated LDL in vitro, and reduced concentrations of alpha-tocopherol and retinol in the precipitated LDL were recorded in the patients with coronary atherosclerosis as compared to the healthy individuals. These results confirm that LDL oxidative-antioxidative disturbances play an important role in the pathogenesis of coronary atherosclerosis.
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PMID:[New biochemical methods for evaluation of the oxidative-antioxidative potential of low-density lipoproteins]. 1600 45

The Apolipoprotein A-V (apoA-V) gene promoter polymorphism -1131T>C modulates triacylglycerol (TG) concentrations. We evaluate whether this polymorphism could be involved in the interindividual variability observed during postprandial lipemia. Fifty-one healthy apo E3E3 male volunteers [12 with -1131CC/CT genotype, and 39 with -1131TT genotype] underwent a Vitamin A fat-load test consisting of 1g of fat/kg body weight and 60,000IU of Vitamin A. Blood samples were taken at time 0 and every hour until the 6th and every 2h and 30 min until the 11th. Cholesterol (Chol) and TG were determined in plasma and Chol, TG, ApoB-100, ApoB-48, and retinyl palmitate (RP) were determined in lipoprotein fractions. Data of postprandial lipemia revealed that subjects with the -1131CT/CC genotype had a higher postprandial response of total plasma TG (p=0.043), large triacylglycerol-rich lipoproteins-TG (TRL-TG) (p=0.002), large TRL-Chol (p=0.004), small TRL-Chol (p=0.004) and small TRL-RP (p=0.001) than subjects with the -1131TT genotype. The modifications observed in postprandial lipoprotein metabolism in subjects with the apoA-V -1131T>C polymorphism could be involved in the increased fasting plasma TG concentrations previously described in carriers of the C allele.
Atherosclerosis 2006 Nov
PMID:A single nucleotide polymorphism of the apolipoprotein A-V gene -1131T>C modulates postprandial lipoprotein metabolism. 1638 43

It has been repeatedly demonstrated that ACTH administration lowers plasma lipid concentrations in man. The present study was designed to test the hypothesis, based on observations of decreased apolipoprotein B (ApoB) synthesis and secretion in vitro, that ACTH administration inhibits the postprandial output of ApoB in man. Therefore, we studied the response to a fat-rich meal supplemented with Vitamin A in eight healthy volunteers, who underwent this test without premedication, after 4 days administration of ACTH, and after 4 days administration of a glucocorticoid (betamethasone). As expected, fasting plasma levels of low-density lipoproteins (LDL)-cholesterol (-25%) and ApoB (-17%) decreased after ACTH, but not after betamethasone administration. Also, the elevation of plasma ApoB-48 in response to fat intake (to twice the basal levels) was markedly reduced after ACTH administration. However, the postprandial rise in plasma triglycerides and retinyl palmitate was unimpaired, suggesting that ACTH administration induced the secretion of fewer but larger chylomicrons. The effect of betamethasone on the postprandial response was similar but less pronounced. This study confirms earlier reports on the lipid-lowering effects of ACTH and supports our theory, based on in vitro studies, that the lipid-lowering effects of ACTH administration in man involves an inhibition of ApoB production.
Atherosclerosis 2007 Apr
PMID:ACTH reduces the rise in ApoB-48 levels after fat intake. 1683 59

Insulin resistance constitutes a pathophysiologic link between obesity, atherosclerosis, and/or cardiovascular complications. Retinol binding protein 4 (RBP4) is a newly discovered adipocyte product that modulates glucose metabolism and consequently induces insulin resistance. We investigated the association between serum RBP4 levels and insulin resistance in obese and nonobese adolescents. A total of 87 nonobese (60 males and 27 females) and 85 obese (62 males and 23 females) apparently healthy adolescents, 12 to 18 years old, were included in this study. A questionnaire was used to obtain participant medical history and lifestyle information, such as smoking and alcohol ingestion habits. Subjects' anthropometric measurements were taken to calculate for body mass index and waist-to-hip ratio. Serum RBP4 levels were measured by an enzyme immunoassay kit. High-sensitivity C-reactive protein, fasting glucose, total cholesterol, triglycerides, high-density lipoprotein cholesterol, and fasting insulin were measured. Low-density lipoprotein cholesterol level and homeostatic model assessment of insulin resistance (HOMA-IR) were calculated. Males had significantly higher RBP4 levels than females. Serum RBP4 levels were significantly higher in the obese group compared with the nonobese group. In all subjects, RBP4 was positively correlated with adiposity index (body mass index, waist circumference, waist-to-hip ratio), systolic and diastolic blood pressures, glucose tolerance index (fasting glucose, insulin, HOMA-IR), lipid profile (total cholesterol, triglycerides), and inflammatory indices (high-sensitivity C-reactive protein, white blood cell count). In multiple linear regression analysis, RBP4 was independently associated with age, HOMA-IR, and triglyceride levels in the nonobese group and with sex and triglyceride levels in the obese group. These results suggest that serum RBP4 might have clinical implications for lipid metabolism and insulin action in adolescents.
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PMID:Association of serum retinol binding protein 4 and insulin resistance in apparently healthy adolescents. 1729 20


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