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

The positive correlation existing between hyperhomocyst(e)inemia [HH(e)] and vascular disease has firmly been established through data derived from numerous epidemiological and experimental observations. Clinical data corroborate that homocysteine (Hcy) is an independent risk factor for coronary, cerebral and peripheral arterial occlusive disease or peripheral venous thrombosis. Hcy is a sulfhydryl-containing amino acid that is formed by the demethylation of methionine. It is normally catalyzed to cystathionine by cystathionine beta-synthase a pyridoxal phosphate-dependent enzyme. Hcy is also remethylated to methionine by 5-methyltetrahydrofolate-Hcy methyltransferase (methionine synthase), a vitamin B12 dependent enzyme and by betaine-Hcy methyltransferase. Nutritional status such as vitamin B12, or vitamin B6, or folate deficiencies and genetic defects such as cystathionine beta-synthase or methylene-tetrahydrofolate reductase may contribute to increasing plasma homocysteine levels. The pathogenesis of Hcy-induced vascular damage may be multifactorial, including direct Hcy damage to the endothelium, stimulation of proliferation of smooth muscle cells, enhanced low-density lipoprotein peroxidation, increase of platelet aggregation, and effects on the coagulation system. Besides adverse effects on the endothelium and vessel wall, Hcy exert a toxic action on neuronal cells trough the stimulation of N-methyl-D-aspartate (NMDA) receptors. Under these conditions, neuronal damage derives from excessive calcium influx and reactive oxygen generation. This mechanism may contribute to the cognitive changes and markedly increased risk of cerebrovascular disease in children and young adults with homocystunuria. Moreover, during stroke, in hiperhomocysteinemic patients, disruption of the blood-brain barrier results in exposure of the brain to near plasma levels of Hcy. The brain is exposed to 15-50 microM H(e). Thus, the neurotoxicity of Hcy acting through the overstimulation of NMDA receptors could contribute to neuronal damage in homocystinuria and HH(e). Since HH(e) is associated with certain neurodegeneratives diseases, in the present review, the molecular mechanisms involved in neurotoxicity due to Hcy are discussed.
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PMID:[Hyperhomocysteinemia: atherothrombosis and neurotoxicity]. 1079 37

Various studies on the relationship between serum cholesterol level and the risk of stroke have been published recently. Subsequent reviews have extrapolated information on stroke from the clinical trials originally aimed at lowering cholesterol for the primary and secondary prevention of myocardial infarction (MI) in middle-aged patients. We have reviewed the epidemiological knowledge on the relationship between serum cholesterol levels and stroke, and also focused on possible reduction of the risk of stroke with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor treatment. Possible benefits from such therapy are particularly relevant for the elderly population which is at particularly high risk for stroke. The effects of serum cholesterol levels on the risk for haemorrhagic and ischaemic stroke have been evaluated. Indirect epidemiological evidence indicates that serum levels of total cholesterol and its subfractions are determinants of stroke, but their associations are relatively weak. When exploring the possible association of serum cholesterol levels with the increased risk of stroke with aging, we concluded that, as in younger adults, elevated total cholesterol and decreased high density lipoprotein-cholesterol levels predispose to ischaemic stroke in the elderly. The mechanism through which serum cholesterol levels increase stroke risk is based on its actions on the artery walls. Indirect evidence suggests that the reduction in the stroke risk with HMG-CoA reductase inhibitors is larger than would be expected with reduction of elevated serum cholesterol level alone. Therefore, antioxidant and endothelium-stabilising properties of HMG-CoA reductase inhibitors may contribute in reducing the risk of stroke in recipients. Lowering high serum cholesterol with HMG-CoA reductase inhibitors has been beneficial in the primary and secondary prevention of MI. No trials have specifically tested the effect of cholesterol lowering with HMG-CoA reductase inhibitors on stroke occurrence. High serum cholesterol levels are a risk factor for ischaemic stroke, although the risk imparted is lower than that for MI. Although the relative risk of stroke associated with elevated serum cholesterol levels is only moderate, its population attributable risk is high given the increase in the elderly population worldwide. The effect of cholesterol reduction with HMG-CoA reductase inhibitors on prevention of ischaemic stroke should be evaluated in prospective, randomised, placebo-controlled trials in the elderly. The tolerability of lipid-lowering drugs in the elderly and the cost effectiveness of primary prevention of stroke using lipid-lowering drugs also needs to be assessed in the elderly.
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PMID:The relationship between cholesterol and stroke: implications for antihyperlipidaemic therapy in older patients. 1093 14

A 14-year-old Chinese boy with a normal perinatal and early developmental history presented at 5 years of age with migraine, intractable epilepsy, ataxia, supraventricular tachycardia, paralytic ileus and progressive mental deterioration. Computerized tomography revealed multiple cerebral infarcts in the parieto-occipital region without basal ganglial calcification. Magnetic resonance imaging showed increased signal intensity in T2 weighted images in the same regions. A cerebral digital subtraction angiogram was normal. Venous lactate, pyruvate, lactate to pyruvate ratio and cerebrospinal fluid lactate were elevated. Muscle biopsy did not reveal any ragged red fibres; dinucleotide-tetrazolium reductase activity was normal. Mitochondrial DNA analysis detected an adenine to guanine mutation at nucleotide position 3243 of tRNALeu(UUR). All four tissues analysed demonstrated heteroplasmy: leucocyte 56%, hair follicle 70%; buccal cell 64%; muscle 54%. The mother and brother of the proband, both asymptomatic, were also found to have a heteroplasmic A3243G mutation in the leucocytes, hair follicle and buccal cells. Other members of the maternal lineage, including the maternal grandmother, did not have the mutation. This report describes a patient with mitochondrial encephalopathy, lactic acidosis, stroke-like episodes, who presented with multisystem involvement. The absence of ragged red fibres in muscle biopsy did not preclude the diagnosis. Mutational analysis of mitochondrial DNA conveniently confirmed the diagnosis of the disorder. A de novo mutation is demonstrated in this family.
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PMID:De novo mutation in the mitochondrial tRNALeu(UUR) gene (A3243G) with rapid segregation resulting in MELAS in the offspring. 1116 79

Recent studies of hydroxy-methylglutaryl coenzyme A reductase inhibitors have demonstrated that therapy with statins is associated with a significant decrease in the risk of stroke and TIA in patients with coronary artery disease. The underlying mechanism responsible for this effect is unclear. The author presents two patients who had cessation of TIAs upon institution of statin therapy. A variety of non-lipid-lowering mechanisms may account for this beneficial effect. This initial observation, if confirmed by further study, may suggest a role for statin agents in preventing recurrent TIAs.
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PMID:Suppression of recurrent transient ischemic attacks by a statin agent. 1122 1

Heterozygosity and/or homozygosity for mutations at the genes of the enzymes involved in homocysteine metabolism may confer an increased risk for thrombosis by causing hyperhomocysteinemia. Although the mutations related to homocysteine metabolism possibly increase the risk of stroke, the data are conflicting and there are very few reports linking these defects to acute stroke in children. We aimed to study the role of these mutations in Turkish children with ischemic stroke. Forty-six patients having cerebral infarct were clinically diagnosed, and the infarction verified with magnetic resonance imaging of the brain was included in the study. All patients were below the age of 18 (10 months to 18 years). Sixty-eight controls, consecutively selected among healthy unrelated subjects from the same geographic area of Turkey without personal and family history of thrombosis, stroke or Behest's disease, were included. Genotyping for the common mutations was carried out by the methods described previously. There was no difference between the pediatric stroke patients and controls for the distribution of methylene tetrahydrofolate reductase (MTHFR) 677 C-T, MTHFR 1298 A-C, methylene tetrahydrofolate dehydrogenase (MTHFD) 1958 G-A and methionine synthase reductase (MTRR) 66 A-G alleles. There was no risk for double gene alterations (MTHFR 677 C-T vs. 1298 A-C) after individuals with FV 1691 A mutation is excluded. Twelve of the 46 patients were found to carry FV 1691 A mutation (26.0%), one being homozygote. The cerebral infarct risk for FV 1691 A was found to be 6.4 (CI 95% 1.7-23.0). Eight of the 46 patients were found to carry PT 20210 A mutation (16.6%). Two of the FV 1691 A heterozygous patients carried PT 20210 A mutation at the same time (4.2%). As a conclusion, we can say that FV 1691 A and PT 20210 A mutations are important and must be included to the routine analysis of pediatric stroke patients.
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PMID:Common mutations at the homocysteine metabolism pathway and pediatric stroke. 1132 21

Simvastatin (Zocortrade mark, Merck) is a safe and effective 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor. Simvastatin potently lowers total and low density lipoprotein (LDL) cholesterol. Simvastatin was the first cholesterol-lowering agent that reduced total mortality in a randomised clinical trial. Simvastatin is effective at reducing total mortality, myocardial infarction, coronary mortality and the incidence of stroke or transient ischemic attack in patients with coronary heart disease and hypercholesterolemia. Simvastatin, like other statins, also has non-lipid mechanisms of action. These include anti-inflammatory effects, antiproliferative effects on smooth muscle cells and an upregulation of endothelial nitric oxide synthase. Overall, simvastatin has an excellent safety profile. Simvastatin, along with other statins, has made a significant impact on the morbidity and mortality from coronary heart disease.
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PMID:Pharmacology and clinical experience with simvastatin. 1133 76

To date, there are no evidence-based data to support specific drug therapy for a patient with atheroembolism. It makes sense to use HMG CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors (statins) in any patient with atherosclerosis, as these drugs have been shown to reduce the risk of myocardial infarction and stroke, and have a theoretical benefit on plaque stabilization. Surgical treatment should be considered for patients with abdominal aortic or popliteal artery aneurysms and downstream atheroembolism. There are case reports of atheroemboli in patients worsening after given warfarin or heparin. For this reason, some institutions are reluctant to prescribe these drugs for patients with atheroemboli or thromboemboli from aortic plaque. However, the incidence of this complication is quite low. Anticoagulation probably should be stopped if a patient develops atheroembolism. Similarly, the current state of knowledge does not allow for selecting specific pharmacologic intervention in patients with thromboemboli from aortic plaque. Statin therapy does make sense, as these drugs theoretically stabilize plaques and prevent plaque hemorrhage, thrombosis, and subsequent embolization. Unstable aortic plaques may develop superimposed thrombi (red thrombi on pathologic examination), easily seen as mobile elements on transesophageal echocardiography. Therefore, it is possible that anticoagulation with warfarin might prevent embolic events in these patients. For this reason, we are often in the position of recommending warfarin therapy for patients with emboli and severe atheromas seen on transesophageal echocardiography, especially when superimposed mobile thrombi are seen. There are small series in the literature that indicate the potential benefit of warfarin. However, until a large multicenter randomized clinical trial is done, the use of warfarin can not be definitively recommended. Antiplatelet agents, although safer than warfarin (less risk of hemorrhage), have not been proven beneficial in patients with thromboembolism from the aorta. Surgery (endarterectomy) of the aortic arch is a very risky procedure that should not be performed routinely, but may be used in highly selected patients.
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PMID:Embolism from the Aorta: Atheroemboli and Thromboemboli. 1134 63

In cardiovascular pharmacotherapy, the main focus is now on statins (HMG-CoA-reductase inhibitors) because of their antihyperlipidaemic and antiatherogenic effect. They are suggested to be beneficial also in senile dementia, stroke and osteoporosis and they can reduce incidence of ventricular arrhythmias in patients with cardioverter-defibrillator. In chronic heart failure, statins should be used with caution since reduced cholesterol levels relate to impaired survival. As an alternative to statins and fibrates, niacin therapy may be considered. ACE inhibitors are of proven benefit for patients with left ventricular dysfunction after acute myocardial infarction; however, in long-term treatment, their protective activity is not superior to that of beta-blockers, diuretics and clonidine. Ca-channel antagonists slightly increase the incidence of cardiovascular complications but reduce the incidence of stroke in high-risk patients. Biventricular pacing has been used with success in patients with severe heart failure and conduction disturbances, and the first permanent artificial ventricle was implanted to a patient with irreversible terminal heart failure in summer 2000. Cardiospecific troponin I may be an uninvasive marker of a procoagulant status indicating e.g. graft failure after cardiac transplantation; T-cadherin belongs to the cell-adhesion molecules and has a role in maintenance of cellular contacts which are critical for the vessel wall architecture. Etamoxir, originally developed for the treatment of diabetes II, has recently been shown to be a potential novel drug for heart failure. Routine use of nitric oxide after congenital heart surgery lessens the risk of pulmonary hypertensive crises.
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PMID:[Cardiology 2000]. 1137 23

It is well established that 3-hydroxy-3-methyglutaryl coenzyme A (HMG-CoA) reductase inhibitors ("statins") reduce cholesterol levels and prevent coronary heart disease (CHD). Although a causal relation between elevated cholesterol levels and stroke has not been well defined, a number of large secondary prevention studies and meta-analyses have shown that statin therapy reduces stroke in patients with CHD and hypercholesterolemia. In addition to the vascular effects of statins (stabilization of atherosclerotic plaques, decreased carotid intimal-medial thickness), there are increasing data to suggest that these agents have additional properties that are potentially neuroprotective. These include endothelial protection via actions on the nitric oxide synthase system, as well as antioxidant, anti-inflammatory and anti-platelet effects. These actions of statins might have potential uses in other neurological disorders such as Alzheimer's disease and certain types of brain tumors.
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PMID:Use of statins in CNS disorders. 1144 Jul 49

Although guidelines for individual risk factors for cardiovascular disease (CVD) assist the healthcare provider, management of the global risk profile of patients is the optimal means to minimize risk. Regardless of whether patients have one or more risk factors, elevated lipid values are generally considered to be a major contributor to global CVD risk. Therefore, reduction of lipid levels is one of the most effective methods to reduce risk of CVD. The 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitor class of drugs (also known as statins) has documented clinical benefits for reducing the incidence of myocardial infarction, stroke, death from CVD, and total death. Despite widespread acknowledgment of the very favorable benefit-to-risk ratio of the statins, most at-risk patients either are not being treated or are not at the goals defined by the National Cholesterol Education Program.
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PMID:Current perspectives on lipid lowering with statins to decrease risk of cardiovascular disease. 1144 51


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