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

Epidemiology call be a useful guide to risk prediction. If, for example, the value of serum cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides as predictors of future CHD events is considered, then generally the triglyceride level measured on a single occasion will add little to the prognostic information contained in cholesterol and HDL cholesterol. The serum triglyceride concentration is, however, often more strongly correlated with future CHD incidence in univariate analysis than is serum cholesterol. However, in multiple logistic regression analysis, particularly when HDL cholesterol is included, the strength of the apparent independent relationship between triglycerides and CHD incidence is weakened often to the point of insignificance in individual trials, although it is still evident on meta-analysis of all the epidemiological trials in which both HDL cholesterol and triglyceride levels were measured. The erosion of the relationship between triglycerides and CHD incidence when HDL is included in multiple logistic regression analysis is to some extent is an artefact of the greater biological variation of triglyceride concentrations compared with HDL cholesterol. When allowance is made for this triglycerides can have more predictive power than HDL. Important clinical decisions are generally not based on single measurements, but on a series which reduces the effect of biological variation. However, even more importantly epidemiology cannot tell us that lowering cholesterol or raising HDL cholesterol levels will have more therapeutic benefit than decreasing triglyceride levels. That can only be established in clinical trials. An overview of trials involving drugs, which have as their principal action triglyceride-lowering, revealed them to decrease CHD incidence as much as statins. In the trials the drugs, which principally lowered triglycerides, also produced small decreases in serum cholesterol. The decrease in CHD incidence was, however, more than would be predicted from a similar reduction in cholesterol achieved with statins. Epidemiology can thus be a poor guide to clinical decisions. Furthermore the epidemiological relationship between cholesterol, triglycerides, HDL and CHD gives us only limited insight into the mechanisms by which these lipids and lipoproteins are involved in atherogenesis and their relative importance in this process. Thus evidence from clinical studies linking hypertriglyceridaemia with potentially important atherogenic factors such as intermediate density lipoproteins, small dense LDL and increased cholesteryl ester exchange may provide a greater understanding of atherogenesis and potential sites of therapeutic intervention than epidemiology. There is thus evidence for the therapeutic value of lowering triglycerides and an emerging view that triglyceride-rich lipoproteins are frequently crucial in atherogenesis.
Atherosclerosis 1998 Dec
PMID:Triglycerides are more important in atherosclerosis than epidemiology has suggested. 988 44

Diabetes mellitus type 2 (DM type 2) is a common disease that is associated with high mortality and morbidity due to macrovascular and microvascular complications. CHD mortality and morbidity is 2-3 times higher in diabetic than in non-diabetic patients. There are many potentially atherogenic factors in diabetes these may underlie this problems. Except major risk factors (high serum cholesterol concentration, hypertension, cigarette smoking), insulin resistance is common in DM type 2 patients. The dyslipidemic component of insulin resistance is "atherogenic lipoprotein phenotype", its components include small LDL particles (pattern B) with higher atherogenic risk. Several recent studies have demonstrated the preponderance of small, dense LDL in patients with DM type 2 and IR. The question of whether small, dense LDL can be explained by triglyceride levels alone or whether it is directly related to DM type 2 and insulin resistance is still the subject of debate. If serum triglycerides exceed 1.3 mmol/l, small, dense LDL increases. The practical implication is that serum triglyceride levels should be maintained as low as possible to prevent the deleterious effects of triglycerides on LDL subclass distribution and size. There are several potential mechanisms to explain the increased atherogenicity of dense LDL (small dense LDL is more susceptible to lipid peroxidation and oxidation leading to its increased uptake by macrophages and subsequent removal by scavenger pathway, also has a lower binding affinity to LDL receptors). Theoretical grounds postulate that the treating of diabetic dyslipoproteinemias would reduce atherosclerosis disease. However, to date, there have been no intervention studies specifically designed to test this postulate in the diabetic population. Such studies the Diabetes Atherosclerosis Intervention Study (DAIS), Fenofibrate Intervention and Event Lowering in Diabetes (FIELD), Collaborative Atorvastatin in Diabetes Study and Lipid in Diabetes Study are currently in progress. (Tab. 4, Fig. 2, Ref. 81.)
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PMID:[Relation between insulin resistance and small, dense lipoproteins with low density and the development of atherosclerosis in type 2 diabetes mellitus]. 991 42

Much debate on the benefits and risks of cholesterol lowering to prevent coronary heart disease has focused on excess non-CHD mortality rates reported in some trials. Because of the wide variation in design of cholesterol-lowering trials and because the non-CHD mortality rate was not a controlled endpoint of statistical power in most published studies, it has been difficult to determine whether any excess mortality was due to certain therapies, to other mechanisms, or to chance. As a result, some investigators have performed retrospective analyses of pooled trial data in order to augment statistical power. Some investigators have hypothesized that the human brain is dependent on a constant supply of cholesterol from the circulation and that cholesterol loss in neuronal membranes, with the possible consequences of behavioral disorders and increased risk of accident and violent death. Indeed Weidner and Griffin suggest that low cholesterol is a marker for poor underlying health; physical illnesses are likely to cause depression and other negative emotional states, which are often accompanied by suppressed appetite and weight loss causing reduction in cholesterol levels. Such mental states may also increase the risk of non-CHD death, for example suicide. Rossouw reviews the evidence concerning non-CHD mortality in cholesterol-lowering trials and reports metaanalyses carried out for all trials combined. The findings indicated a significant (15%) increase in non-CHD mortality in all trials combined. However, this was not related to cholesterol lowering itself, because there was no increased risk in trials with > 10% cholesterol reduction, whereas there was a significant (22%) increase in trials with lesser degrees of cholesterol lowering. The publication of a large secondary prevention trial (4S) employing Simvastatin for cholesterol lowering supports the idea that cholesterol reduction itself does not have adverse effects on non-CHD mortality. The overview of all published trials demonstrates their effectiveness in reducing cholesterol and provides clear evidence of benefits on stroke and total mortality. A 10% reduction in cholesterol yielded about a 20% decrease in CHD mortality, which would be expected to result in about a 6% reduction in total mortality. Endothelium-dependent relaxations are reduced in hyperlipidemia and atherosclerosis. Exogenous L-arginine improves or restores the reduced endothelium-dependent relaxations. Moreover inflammation is associates with the initiation and progression of atherosclerosis. The fact of the matter is the Cardiovascular drugs already in clinical use or in development are able to interfere with certain aspects of endothelial function and may be useful in protecting the vessels and, hence, in preventing the development of cardiovascular disease.
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PMID:[All mortality by cause of death. The challenge of coronary prevention]. 1005 Jan 41

The aim of this review was to bring together results obtained from studies on different aspects of HDL as related to CHD and atherosclerosis. As atherosclerosis is a multistep process, the various components of HDL can intervene at different stages, such as induction of monocyte adhesion molecules, prevention of LDL modification and removal of excess cholesterol by reverse cholesterol transport. Transgenic technology has provided a model for atherosclerosis, and permitted evaluation of the contributions of different HDL components towards the global effect. The availability of apo AIV transgenic mice amplified the results obtained from apo AI overexpressors with respect to prevention of atherosclerosis. Prevention of atherosclerosis in apo E deficient mice by relatively small amounts of macrophage derived apo E may open new possibilities for therapeutic intervention. Contrary to early notions, increased plasma levels of CETP, even in the presence of low but functionally normal HDL, were atheroprotective. The extent to which paraoxonase and apo J participate in prevention of human atherosclerosis needs further evaluation. The findings that LCAT overexpression in rabbits was atheroprotective in contrast to increase in atherosclerosis in h LCAT tg mice, which was only partially corrected by CETP expression, call for some caution in the extrapolation of results from transgenic animals to humans. The important discovery of SR-BI as the receptor for selective uptake of CE from HDL revived interest in the clearance of CE from plasma. This pathway supplies also the vital precursor for steroidogenesis in adrenals and gonads and was shown to be dependent on apo AI.
Atherosclerosis 1999 Jun
PMID:Atheroprotective mechanisms of HDL. 1040 90

Sialic acid is a negatively charged sugar associated with the protein and lipid portions of lipoproteins. Sialic acid has been hypothesised to play an anti-atherogenic role in lipoprotein metabolism through the electrostatic inhibition of lipoprotein interactions with chondroitin-6-sulphate-rich arterial proteoglycans (APG). We conducted a series of studies using native and modified lipoproteins (VLDL1 Sf 60-400, VLDL2 Sf 20-60, IDL1 Sf 16-20, IDL2 Sf 12-16, LDL(A) Sf 8-12, and LDL(B) Sf0-8) that vary in their sialic acid content to examine the relationship between lipoprotein sialic acid content and its interaction with APG. Lipoprotein sialic acid was greatest in VLDL1 and decreased progressively with particle density until the IDL2 fraction (VLDL1 > VLDL2 > IDL1 > IDL2 = LDL(A) = LDL(B)). The pattern of reactivity of each fraction with APG was different from the pattern observed for lipoprotein sialic acid content (IDL2 > LDL(A) > LDL(B) > IDL1 > VLDL2 > VLDL1). Levels of sialic acid were lower in subjects with CHD as compared to control subjects but the presence of CHD had no effect on lipoprotein-APG complex formation when sex and plasma triglyceride levels were taken into account. There was also no significant relationship between the lipoprotein sialic acid content and the reactivity with APG within each lipoprotein fraction. Treatment of hypertriglyceridaemic subjects with ciprofibrate decreased lipoprotein-APG complex formation in all lipoprotein fractions. This was associated with a decrease in the total sialic acid content of apo B100-containing lipoproteins suggesting that the total sialic acid content of apo B100-containing lipoproteins has no influence on lipoprotein-APG complex formation. We next conducted in vitro experiments to manipulate LDL sialic acid content. Enzymatic removal of sialic acid from LDL with neuraminidase resulted in an increase in LDL-APG complex formation. This was accompanied by an increase in the exposure of free amino groups on LDL possibly due to disruption of interactions between free amino groups and sialic acid-containing components on LDL. Increasing LDL sialic acid content through incubation with ganglioside resulted in a decrease in lipoprotein-APG complex formation without any changes in the exposure of free amino groups on LDL. We conclude that total sialic acid content of lipoproteins is not a major determinant of their binding to APG. However, specific sialic acid-containing components on lipoproteins can affect their interaction with APG.
Atherosclerosis 1999 Aug
PMID:Sialic acid-containing components of lipoproteins influence lipoprotein-proteoglycan interactions. 1048 50

The normal endothelium is characterised by the production of a number of molecules which affect the contractile state of adjacent myocytes and the behavior of formed elements within the blood stream, and by the absence of cell surface adhesion molecules. In addition, endothelial cells are important modulators of coagulation and fibrinolysis. Whilst effects of lipids have been documented on many of these endothelial processes, there is particularly strong evidence for effects on the vasodilatation mediated by endothelium derived nitric oxide and on the interaction between leukocytes and the endothelial surface. Both LDL cholesterol and triglyceride rich lipoproteins impair endothelium dependent vasodilatation. The effects of LDL cholesterol are primarily evident for lipoprotein particles that have been oxidised with evidence for effects of specific constituents of oxidised LDL, such as lysophosphatidylcholine (LPC). LDL effects have been demonstrated at numerous sites of the nitric oxide signaling pathway including receptor-G protein coupling, nitric oxide synthase and NO bioactivity, with evidence for enhanced superoxide formation and the consequent production of the less potent dilator peroxynitrite. The effects of lipids on endothelium dependent vasodilatation can be reversed not only by reducing the level of elevated lipids levels but also by provision of the NOS substrate, L-arginine and by the provision of antioxidants, although the mechanism for these effects are not fully elucidated. The adhesion of leukocytes to the endothelial surface is stimulated by low density and triglyceride rich lipoproteins. As with endothelium dependent vasodilatation, the effects of LDL cholesterol are primarily evident for low-density lipoprotein particles that have been oxidised, and many of the effects of oxidised LDL can be mimicked by LPC. HDL can overcome pro-adhesive effects of oxidised LDL. The effects of LDL on leukocyte adhesion are secondary to the expression of adhesion molecules on the luminal surfaces of endothelial cells. In addition to the likely deleterious effects of lipids on endothelium-mediated vasodilatation and leukocyte-endothelial cell interaction, lipids have been shown to affect a number of other endothelial processes and function. Thus, oxidised LDL affects endothelial ET1 and PGI2 release. Although effects have been shown on endothelial cell growth and apoptosis and on endothelial processes related to thrombosis and fibrinolysis, these effects have been less extensively studied than endothelial dependent vasodilatation and leukocyte-endothelial cell interaction. Many of the effects of elevated or modified low density and TG rich lipoproteins on endothelial cells and endothelial cell processes could be expected to contribute to the development of atherosclerosis and therefore, to the association between lipids and atherosclerotic, particularly coronary, vascular disease. However, the extent to which "endothelial dysfunction" accounts for the known relationships between serum lipid concentrations and CHD is yet to be established.
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PMID:Lipids and the endothelium. 1053 61

A total of 531 patients from 57 hospital centres across the UK, who had previously been treated with lipid-lowering agents in combination or alone, in whom the degree of cholesterol reduction was insufficient to achieve European Atherosclerosis Society target levels, were treated with atorvastatin over a 12-week period. The dose of atorvastatin (10, 20 or 80 mg/day) was determined by assignment of risk based on entry level cholesterol levels and the presence of other established CHD risk factors. Atorvastatin was successful in achieving target LDL-cholesterol levels in 86% of mild risk patients, 88% of moderate risk patients and 52% of high risk patients. Compliance with atorvastatin was 96% and treatment was well tolerated. This study demonstrates that atorvastatin is effective in achieving target lipid levels in a large proportion of patients and that the dose required can be predicted by an assessment of the patient's risk profile.
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PMID:An assessment of the efficacy of atorvastatin in treating patients with dyslipidaemia to target LDL-cholesterol goals: the atorvastatin matrix study. 1069 35

Decision levels of diabetes mellitus and hyperlipidemia in elderly subjects as well as younger subjects should be determined to prevent complications of these diseases such as microvascular and macrovascular diseases. Therefore, prospective follow-up study is necessary to decide the decision levels. In the case of diabetes mellitus, there are some useful studies such as KUMAMOTO STUDY show that strict glycemic control can prevent microvascular diseases, but there are few studies in elderly subjects. However, hypoglycemia causes macrovascular events, and chronic hypoglycemia leads to dementia and apathy. It is generally accepted that the glycemic control level can be milder than that in younger subjects. We suggest that the following decision levels are reasonable for elderly diabetic subjects, 1. FPG > 140-160 mg/dl, 2. PG(2 h) > 200-250 mg/dl, 3. HbA1c > 7-8%. Decision level of hyperlipidemia in elderly subjects should also be determined to prevent cardiovascular disease. It is demonstrated that anti-hyperlipidemic treatment can prevent CHD even in elderly subjects by many prospective studies. Japan Atherosclerosis Society recommend that the decision levels of hyperlipidemia in elderly subjects can be the same as younger subjects. The decision levels indicating diet therapy and medication for risk factor free subjects(category A) are LDL-C > or = 140 and 160 mg/dl, respectively. Those for subjects without CHD but have some risk factors(category B) are LDL-C > or = 120 and 140 mg/dl, respectively. Those for subjects with CHD(category C) are LDL-C > or = 100 and 120 mg/dl, respectively.
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PMID:[Decision levels of diabetes mellitus and hyperlipidemia in elderly Japanese subjects]. 1080 29

The validity of the death certificate in identifying coronary heart disease deaths was evaluated using data from the community surveillance component of the Atherosclerosis Risk in Communities Study (ARIC). Deaths in the four ARIC communities of Forsyth Co., NC; Jackson, MS; Minneapolis, MN; and Washington Co., MD were selected based on underlying cause of death codes as determined by the rules of the ninth revision of the International Classification of Diseases (ICD-9). Information about the deaths was gathered through informant interviews, physician or coroner questionnaires, and medical record abstraction, and was used to validate the cause of death. Sensitivity, specificity, and positive predictive value of the death certificate classification of CHD death (ICD-9 codes 410-414 and 429.2) were estimated by comparison with the validated cause of death based on physician review of all available information. Results from 9 years of surveillance included a positive predictive value 0.67 (95% CI 0.66-0.68), sensitivity of 0.81 (95% CI 0.79-0.83), and a false-positive rate (1-specificity) of 0.28 (95% CI 0.26-0.30). Comparing CHD deaths as defined by the death certificate with validated CHD deaths indicated that the death certificate overestimated CHD mortality by approximately 20% in the ARIC communities. Within subgroups, death certificate overestimation was reduced with advancing age (up to age 74), was consistent over time, was not dependent on gender, and exhibited considerable variation among communities.
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PMID:Validation of death certificate diagnosis for coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) Study. 1116 67

Glutathione S-transferases M1 or T1 (GSTM1/GSTT1) affect the body's ability either to detoxify or to activate chemicals in cigarette smoke. Cigarette smoking increases the risk of lower extremity arterial disease (LEAD). We conducted a cross-sectional study to evaluate a hypothesized interaction of the genetic polymorphisms of GSTM1 and T1 with cigarette smoking in the risk of LEAD in the ARIC study. A stratified-random sample, including 212 LEAD cases (ankle-brachial index <0.9 in men or <0.85 in women) and 1277 non-cases, was selected from the ARIC cohort of 12041 middle-aged participants free of CHD, transient ischemic attack and stroke at baseline (1987-1989). Overall, the differences in the frequencies of GSTM1-0 and GSTT1-0 (the homozygous deletion genotype) were not statistically significant between cases and non-cases (44 vs. 41% and 28 vs. 18%). However, smoking was more prevalent among LEAD cases than non-cases. The results suggest that the non-deletion genotype GSTM1-1 interacts with smoking to increase the risk of LEAD, but this interaction was not statistically significant. The functional genotype GSTT1-1 was significantly associated with increased risk of LEAD given smoking after adjustment for other risk factors. In individuals with GSTT1-1, the odds ratios (ORs) (95% confidence intervals) of LEAD were 3.6 (1.4, 9.0) for current smoking and 5.0 (1.9, 13.0) for 20+ pack-years. However, in those with GSTT1-0, the ORs were 0.8 (0.2, 2.8) for current smoking and 0.6 (0.1, 2.1) for 20+ pack-years. The interaction was significant (P<0.05) on the additive scale for current smoking and on both the additive and multiplicative scales for 20+ pack-years. Among non-smokers, GSTT1-1 was not associated with LEAD. The results suggest that the GSTT1-1 polymorphism may be a susceptibility factor modifying the risk of LEAD associated with cigarette smoking.
Atherosclerosis 2001 Feb 15
PMID:Interaction of the glutathione S-transferase genes and cigarette smoking on risk of lower extremity arterial disease: the Atherosclerosis Risk in Communities (ARIC) study. 1125 76


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