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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Homocysteine (HC) at concentrations of from 0.05 to 1.0 mM caused dose-dependent loss of [Mg2+]i in cultured cerebral vascular smooth muscle cells (VSMC), whereas cysteine and methionine (its metabolic products) failed to interfere with changes in [Mg2+]i. HC, methionine and cysteine did not produce any changes in [Ca2+]i. Lowering [Mg2+]o to 0.3 mM resulted in elevation of [Ca2+]i and loss of [Mg2+]i. Depletion of [Mg2+]i, induced by HC, was potentiated by low Mg2+. Preincubation of these cells with vitamin B6, vitamin B12, folic acid, alone, did not alter [Ca2+]i or [Mg2+]i. Likewise, concomitant addition of vitamin B6, vitamin B12, or folic acid, together with HC (1 mM) did not change the reduction in [Mg2+]i induced by HC. However, concomitant addition of HC and the three vitamins inhibited completely the loss of [Mg2+]i. Exposure of these cells to each vitamin, alone, or combination of the three vitamins failed to interfere with reduction in [Mg2+]i induced by low [Mg2+]i, but it did suppress the rise in [Ca2+]i. Interestingly, in the presence of low [Mg2+]o, the vitamin combination did not retard depletion of [Mg2+]i. The present findings are compatible with the hypothesis that an increased serum HC concentration causes abnormal metabolism of Mg2+ in cerebral VSMC, thus priming these cells for HC-induced atherogenesis, cerebral vasospasm and stroke. Our results suggest the need for the three B-vitamins, together with normal physiological levels of Mg2+, in order to prevent [Mg2+]i depletion and occlusive cerebral vascular diseases induced by homocysteinemia.
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PMID:Extracellular magnesium regulates effects of vitamin B6, B12 and folate on homocysteinemia-induced depletion of intracellular free magnesium ions in canine cerebral vascular smooth muscle cells: possible relationship to [Ca2+]i, atherogenesis and stroke. 1055 43

HYPERHOMOCYSTEINEMIA: There are experimental data arguing for a role of homocysteine in several processes involved in atherosclerosis. Multiple retrospective and prospective studies performed in populations with high cardiovascular risk have shown that high homocysteine levels are associated with increased risk of coronary artery disease, stroke and peripheral vascular disease. In populations free of cardiovascular disease, prospective studies have demonstrated that homocysteine is a risk factor for cardiovascular disease while in other publications, no such prognostic value is found for high serum levels of homocysteine. PERSPECTIVE AND PREVENTION: There are highly promising perspectives for prevention due to the fact that serum homocysteine levels fall off systematically after simple dietary supplementation with vitamin B. Nevertheless, there is no formal proof to date from therapeutic trials suggesting that such a supplementation would reduce the risk of cardiovascular disease. FURTHER INFORMATION REQUIRED: In terms of epidemiology and clinical expression, further research into homocysteine as a cardiovascular risk factor should not be based on case-control studies which can be expected to provide information of limited usefulness, but rather on interventional trials to determine the primary or secondary preventive effect on cardiovascular disease. A large-scale pragmatic study using diet supplementation in a wide population might provide answers to still open questions.
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PMID:[Homocysteine and cardiovascular disease: what is the connection?]. 1055 15

Homocysteine is a sulphur-containing amino acid formed during metabolism by one of two pathways by remethylation and transsulfuration. Altered homocysteine metabolism may be implicated as a factor in atherosclerosis, cerebrovascular disease or peripheral vascular disease. It is postulated that homocysteine may damage endothelial cells or acts as a direct causal factor in the thromboembolic process. Several studies have reported that there are a number of factors that may influence levels of homocysteine in humans. Serum homocysteine levels may be associated with low levels of folate, vitamin B6 and vitamin B12. These studies showed that serum homocysteine levels were higher in men and older adults, and some showed that there was a direct relationship between homocysteine and cigarette smoking, diabetes, obesity, and hypertension. Subjects who consume larger amounts of coffee were also noted to have higher serum homocysteine levels. Several cross-sectional, case-control, and cohort studies have linked homocysteinaemia with cardiovascular disease morbidity and mortality. In the Framingham Heart Study, the cohort study in Tromso, Norway, and the Atherosclerosis Risk in Communities (ARIC) Study, homocysteine levels were found to be higher in adults with asymptomatic or symptomatic coronary artery disease. In the British Regional Heart Study, homocysteine levels were found to be significantly higher in patients with stroke. Thus, there are suggestions that vitamin therapy and alteration of lifestyle habits such as cigarette smoking may lower homocysteine levels. There may be less coronary heart disease morbidity and mortality with lower homocysteine levels.
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PMID:Homocysteine and atherosclerotic disease: the epidemiologic evidence. 1056 72

A surprising number of extra-gastrointestinal diseases have been reported to be associated with Helicobacter pylori infection, including coronary heart disease and stroke. Since coronary heart disease is the principal cause of death in western countries, and since the known risk factors cannot fully explain the pathogenic mechanisms of the disease, the exploration of the role of possible causal agents has stimulated intense research. Infectious agents have been linked to coronary heart disease on epidemiological and pathogenic grounds. In 1994, H. pylori infection was reported to be one of them. Since then, a number of studies have been published with controversial results. Studies performed thus far show a high degree of heterogeneity in the selection of patients and also in the type of disease studied, i.e. coronary heart disease in general or acute myocardial infarction. Since the pathogenic development is most likely different for each of these two conditions (one chronic and the other acute) they should be studied separately. H. pylori infection can cause platelet aggregation and induces a procoagulant activity. H. pylori can also contribute to atherosclerosis, through increased concentration of homocysteine in the blood, caused by decreased levels of folic acid and cobalamin, or to an autoimmune process. Prospective cohort studies and interventional trials focusing separately on the chronic and acute phases of coronary heart disease and H. pylori infection should be performed in order to provide firm epidemiological data for a causal relationship.
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PMID:Helicobacter pylori: from the stomach to the heart. 1056 51

Cardiovascular disease, including coronary heart disease and stroke, is the leading cause of death in the United States. Elevated plasma homocysteine (Hcy), generally defined as fasting plasma Hcy levels >15 micromol/L, is an independent risk factor for vascular diseases (1,2). It is unknown whether Hcy is a cause of or a marker for atherosclerosis. A recent statement by the Nutrition Committee of the American Heart Association concluded that until results of clinical trials are available, population-wide Hcy screening is not recommended (3). However, Hcy tests are used in the clinical setting and information on interlaboratory variation, on method variation, is limited. To assess the status of interlaboratory and intralaboratory variation for Hcy analysis, CDC conducted a study of selected laboratories during July-September 1998. This report summarizes findings from the study, which indicates a need to improve analytic precision and to decrease analytic differences among laboratories (4).
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PMID:Assessment of laboratory tests for plasma homocysteine--selected laboratories, July-September 1998. 1057 90

In a cross-sectional study of 293 nondiabetic patients (169 men and 124 women) referred for the diagnosis and treatment of hyperlipidemia, our specific aim was to determine whether fasting serum insulin independently contributes to the prediction of atherosclerotic cardiovascular disease (ASCVD) status. Of the 169 men and 124 women, 65 (38%) and 44 (35%), respectively, had ASCVD with at least one of the following: unstable angina, myocardial infarction (MI), angioplasty, coronary artery bypass graft (CABG), claudication, transient ischemic attack, or ischemic stroke. In addition, 42% and 38% had fasting hyperinsulinemia (> or =20 microU/mL). Fasting serum insulin of 20 microU/mL or higher was very common in women (59% to 100%) and men (67% to 88%) when hypertension, obesity, top-decile triglyceride (TG), and bottom-decile high-density lipoprotein cholesterol (HDLC) were concurrent in various combinations. ASCVD events (present or absent) were dependent variables in a stepwise logistic regression model with explanatory variables including age, gender, race, hypertension, cigarette smoking, ASCVD in first-degree relatives at age 55 years or less, Quetelet Index, fasting serum insulin, a gender x insulin interaction term, anticardiolipin antibodies (ACLAs) IgG and IgM, total cholesterol to HDLC ratio, TG, lipoprotein(a) [Lp(a)], and homocysteine. The risk odds ratio for ASCVD (109 events and 184 nonevents) for subjects with top-decile insulin (vthe bottom nine deciles) was 3.71, with a 95% confidence interval (CI) of 1.62 to 8.9 (P = .002). For patients with MI and/or CABG and/or angioplasty ([MCA] 63 events and 184 nonevents), the risk odds ratio for top-decile insulin versus the rest was 5.07 (95% CI, 1.83 to 14.8, P = .002). For patients with MCA at age 55 or less, the gender x insulin interaction term was significant (P = .0004); the risk odds ratio for men with top-decile insulin was 13.28 (95% CI, 3.82 to 51.65, P = .0001). Hyperinsulinemia is very common in nondiabetic hyperlipidemic women and men. Fasting serum insulin, a crude, simple, practical, and inexpensive measure, independently and uniformly improved the prediction of ASCVD status beyond traditional risk factors and lipid variables in patients referred for treatment of hyperlipidemia.
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PMID:Contribution of fasting hyperinsulinemia to prediction of atherosclerotic cardiovascular disease status in 293 hyperlipidemic patients. 1058 54

Hyperhomocysteinaemia has been identified as an independent risk factor for atherosclerotic and thromboembolic diseases such as cerebro-vascular diseases, coronary artery disease and venous thrombosis. This review will discuss the role of high levels of plasma homocysteine in stroke disease.
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PMID:Can lowering homocysteine levels reduce the incidence of stroke? 1058 95

In the more than 50 years since the founding of the National Heart, Lung, and Blood Institute and the American Heart Association, medical science has moved from an era in which hypercholesterolemia, as it is now defined, was not believed to be abnormal to one in which controlling hypercholesterolemia is known to reduce not only coronary artery disease morbidity and mortality but also total mortality. While the efforts and successes of many researchers involved in this evolution are impressive, atherosclerosis is still a major cause of death and disability in many developed nations, mostly in the form of myocardial infarction and stroke, and is an increasing cause of morbidity and mortality in developing nations. Many questions about the detailed pathogenesis of the disease remain. Elucidating the roles of high-density lipoprotein, other lipoproteins, and homocysteine, as well as the roles of cytokines and growth factors, will permit better understanding and treatment of atherosclerosis. With continuing support for research and encouragement of physicians and patients to follow recommended preventive regimens, further progress can be made against this major cause of death.
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PMID:Preventing coronary artery disease by lowering cholesterol levels: fifty years from bench to bedside. 1059 87

Inherited gene defects related to the coagulation system have been reported as risk factors for ischemic stroke. These gene defects include a G-A transition at nucleotide 1691 in exon 10 of the Factor V gene causing activated protein C resistance; a G-A transition in the 3' untranslated region of the prothrombin gene at nucleotide position 20210 (G-A), which is associated with increased levels of prothrombin activity; and a C-T polymorphism at nucleotide 677 in the methylenetetrahydrofolate reductase gene responsible for an alanine to valine substitution, resulting in the synthesis of a thermolabile form of methylenetetrahydrofolate reductase that causes increased levels of homocysteine. The case-control study included 28 patients with cerebral infarction; all were 18 years of age or younger (range, 10 months to 18 years). Seven (25%) of the 28 patients were heterozygous for the FV1691 mutation. Five (17.8%) of the patients carried the PT20210A mutation. Two (7.1%) of the patients carried both mutations. When compared to controls, the difference was significant for both mutations (P = .007; .04). The frequency of allele T of methylenetetrahydrofolate reductase 677 was 0.3214, which was not significant when compared to controls (0.231; P = .3). A total of 12 (42.8%) patients carried one or both of the mutations FV1691 G-A and PT20210 G-A. From our data, it appears that FV1691 G-A and PT20210 G-A are associated with cerebral infarct risk independently. Risk assessment of double prothrombotic gene alterations did not reveal synergy between these mutations. In conclusion, the presence of FV1691 A and PT20210 A mutations but not the methylenetetrahydrofolate reductase 677 TT mutation correlate with the occurrence of cerebral infarction in children.
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PMID:Factor V1691 G-A, prothrombin 20210 G-A, and methylenetetrahydrofolate reductase 677 C-T variants in Turkish children with cerebral infarct. 1059 55

The objectives of this study were to describe the distribution of serum levels of total homocysteine (HCys) in a sample of older patients consecutively admitted following acute ischemic cerebral stroke, as compared with healthy controls, and to test for possible relationships of HCys levels to some of the prevalent cardiovascular diseases in these stroke patients. One hundred and thirty-seven stroke patients and 132 healthy controls (age > or =60) participated in this study. HCys levels were determined by HPLC method with fluorescence detection. Correlates of HCys levels and clinical data were examined. The results showed that stroke patients (mean age 74.6+/-9.2) had higher HCys levels as compared with controls (13.8 and 9.8 respectively, p<0.001). Advanced age, male gender, absence of diabetes and a positive history of previous myocardial infarction were the factors associated with HCys levels higher than 10 mmol/L (Odds ratio 2.72, 2.54, 3.12, 3.55, respectively). We conclude that hyperhomocysteinemia is prevalent in older patients with acute ischemic stroke. Few factors associated with increased risk for hyperhomocysteinemia in these stroke patients were identified. The study supports earlier observations regarding elevated HCys levels in stroke patients and increased prevalence of associated cardiovascular disease.
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PMID:The relation of plasma total homocysteine levels to prevalent cardiovascular disease in older patients with ischemic stroke. 1074 32


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