Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hyperhomocysteinemia is a condition which, in the absence of kidney disease, indicates a disrupted sulfur amino acid metabolism, either because of vitamin deficiency (folate, B12 and B6) or a genetic defect. Epidemiologic evidence suggests that mild hyperhomocysteinemia is associated with increased risk of arteriosclerotic disease and stroke. The relationship between hyperhomocysteinemia and thrombosis has been investigated in 10 studies involving a total of 1200 patients and 1200 controls. Eight of these studies demonstrated positive association with odds ratios that ranged from two to 13. This association was enhanced by including a methionine loading test. There is some evidence which suggests that hyperhomocysteinemia and activated protein C resistance have synergistic effect on the onset of thrombotic disease. Recent studies with animal models for mild hyperhomocysteinemia provided encouraging results in the understanding of the mechanism that underlies this relationship between mild elevations of plasma homocysteine and vascular disease. These animal models pointed to the possibility that the effect of elevated homocysteine is multifactorial, affecting both the vascular wall structure and the blood coagulation system.
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PMID:Relationship between homocysteine and thrombotic disease. 970 66

We evaluated 81 thalassaemia major and 4 thalassaemia intermedia patients (48 M, 37 F), median age 17 years; 62/85 patients were HCV-positive, 3/85 HIV-positive, 19/85 were splenectomized. Forty normal healthy children were recruited as the control group. The number of thrombotic events was studied retrospectively. Platelet poor plasma was filtered and quick-frozen at -70 degrees C until time of assay. APC resistance was measured in an activated thromboplastin time and results were expressed as normalized ratio. All tests were done with diluted 1 in 5 (v/v) factor V deficient plasma and with undiluted plasma. Molecular genetic investigation of factor V gene was performed with polymerase chain reaction, followed by digestion of amplified products with restriction enzyme Mnl I. Data obtained with molecular investigation revealed the presence of 4 heterozygous subjects for factor V Leiden (4.7%). Functional tests were able to detect all heterozygotes for factor V Leiden both with undiluted and with diluted plasma, and there were no false negative subjects. However, undiluted plasma revealed a greater number of false positive subjects (n=15) than did diluted plasma. Therefore, tests done with undiluted and diluted plasma revealed a 100% sensitivity, while specificity was 81% for undiluted plasma and 97% for diluted plasma. Only one thrombotic event was observed in one of the 85 studied patients, as a case of stroke in a thalassaemia intermedia patient with APC resistance. In the same patient an additional thrombogenic risk factor was represented by a pronounced haematocrit increase at the beginning of her transfusion regimen.
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PMID:Resistance to activated protein C in thalassaemic patients: an underlying cause of thrombosis. 971 25

This paper presents the role of inhibitory protein C in the haemostatic processes, types of its deficiency and current opinions concerning the role of protein C deficiency in the pathogenesis of stroke. Deficiency of protein C (PC) or activated protein C resistance (both hereditary and acquired) play a role in pathogenesis of stroke, but not so great as it was thought until quite lately. Isolated protein C deficiency in old patients does not increase the risk of stroke. But in children hereditary deficiency of PC or activated PC resistance are of great importance in pathogenesis of ischaemic or venous stroke. In the presence of additional risk factors both in children and in adults deficiency of PC may be an important condition leading to stroke occurrence.
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PMID:[The role of protein C in the pathogenesis of stroke]. 976 May 56

Today, more than 40% of all patients who develop a thrombosis are found to have inherited thrombophilia. The most common cause of this is APC resistance, which can usually be traced back to factor V-Leiden. In the commonly heterozygous patients the risk of thrombosis is increased about 7-fold (life-long risk of thrombosis 10 to 15%). In most cases, however, additional thrombogenic stimuli are required (oral contraception, pregnancy, surgery, immobilization). In combination with oral contraceptives, the risk is increased roughly 30-fold. In contrast, APC resistance does not present an increased risk for thrombosis in the arterial system (myocardial infarction, stroke). Four further inherited or acquired disorders of the hemostatic system are known: prothrombin dimorphism, antithrombin, protein C and protein S deficiencies. Prothrombin dimorphism, the second most common form of inherited thrombophilia, has been known only for the past two years and elevates the risk of thrombosis only to a moderate degree. Today, a search for thrombophilic factors should be carried out not only in young patients with spontaneous development of thrombosis, but also in elderly patients, even when an additional risk for the occurrence of thrombosis such as traumatization or immobilization is present. Therapeutic consequences are discussed.
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PMID:[Thrombophilia caused by congenital disorders of blood coagulation]. 984 71

A patent foramen ovale (PFO) is found by transesophageal echocardiography in one half of patients with cryptogenic stroke (CS). Coagulation abnormalities may promote paradoxical emboli in these patients. Seventeen patients were identified with PFO and CS. Thirty-one percent of patients had hematologic risk factors for venous thrombosis. These included abnormal activated protein C resistance and increased anticardiolipin antibodies. Patients with coagulation abnormalities and a PFO were three times as likely to be treated with warfarin compared to aspirin (P<0.05). Prothrombotic states are common in patients with PFO and CS and identifying these conditions may impact the choice of antithrombotic therapy.
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PMID:Coagulation abnormalities in adults with cryptogenic stroke and patent foramen ovale. 984 98

The anticoagulant transmembrane glycoprotein thrombomodulin (TM) is expressed at the luminal surface of vascular endothelial cells. Recently, we showed that TM antigen and TM mRNA are expressed in brain microvessels in several species and that brain capillaries have the capability to activate protein C. The activation of protein C in brain microcirculation was greatly impaired by major stroke risk factors in rats due to downregulation of TM. In this study, a partial sequence of TM was determined from TM mRNA from brain capillaries examined in brain capillaries of the rat, a species that provides a useful model to investigate stroke mechanisms in relation to brain hemostasis. The predicted deduced amino acid sequences for rat TM were compared with other TM sequences. Particularly high homology (77-100%) among functional domains of the protein, i.e., the epidermal growth factor repeats (EGFRs) 1-6 and the transmembrane region, was observed between mice and rats. Somewhat less degree of homology was observed for bovine and human EGFRs 1-6, while the homology of the transmembrane region was 92-96%. All cysteine residues were conserved among the TM sequences, and specific amino acids previously suggested to be essential for activation of protein C by thrombin TM were highly conserved. We conclude that the highly conserved mRNA and protein sequences may reflect a similar anticoagulant role of TM in brain endothelial and systemic vascular endothelial cells across different species.
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PMID:Rat brain capillary thrombomodulin: structure and function. 985 12

Migraine, particularly migraine with aura (MA), may be a risk factor for ischemic stroke (IS). The reasons for this association are unknown. We investigated the presence of genetic abnormalities of the protein C system in 83 MA patients, 31 IS patients, and 124 healthy controls, all aged under 45 years. We found an increased frequency of activated protein C resistance due to Arg506Gln factor V mutation, and of protein S deficiency in both disorders, with figures higher than those reported in the general population and significantly different from those found in controls. These prothrombotic genetic abnormalities may be shared risk factors in IS and MA, and may play a role in increasing the risk of cerebrovascular disease in migraineurs.
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PMID:Genetic abnormalities of the protein C system: shared risk factors in young adults with migraine with aura and with ischemic stroke? 987 85

Experimental evidence suggests a stimulatory effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on both platelets and coagulation. RhG-CSF is increasingly used to stimulate healthy volunteer donors for blood stem cell mobilization. We therefore assessed 25 healthy donors receiving rhG-CSF for changes in in vitro bleeding test (IVBT), coagulation parameters and cerebral microembolism by transcranial Doppler (TCD) ultrasound. A significant shortening of IVBT was found on day 4 of rhG-CSF administration together with increased levels of fibrinogen and factor VIII and reduced activities of protein C and protein S. Although these changes are quite small it is possible that they may lead to a hypercoagulable state especially in donors with other risk factors for thromboembolism. However, TCD examination failed to detect any signs of microembolism. We therefore conclude that rhG-CSF leads to significant changes in coagulation parameters, but has no effect on TCD detectable microembolism as a stroke risk factor. However donors receiving rhG-CSF should be examined carefully to detect pre-existing changes in the coagulation system and we would like to suggest a routine thrombophilia screen.
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PMID:Analysis of rhG-CSF-effects on platelets by in vitro bleeding test and transcranial Doppler ultrasound examination. 987 71

The carbohydrate-deficient glycoprotein syndromes are a group of recently described autosomal recessive, metabolic defects affecting multiple systems. The disorder is caused by inefficient posttranslational glycosylation of glycoproteins. Patients with the syndrome present early in life with psychomotor retardation, seizures, hypotonia, and stroke-like episodes. They also have dysmorphic features including almond-shaped eyes, constant squint, inverted nipples, and buttock fat pads. One of the features of the syndrome is coagulopathy, and we report here a patient who presented with a prolonged activated partial thromboplastin time, and was subsequently diagnosed with the carbohydrate-deficient glycoprotein syndrome. We also summarize the results of five previously published studies of the coagulation system in these patients. Most of the reported patients are deficient in factor XI, protein C, antithrombin III, and protein S. Other coagulation proteins are less frequently affected. Both bleeding and thrombosis have been observed, yet the cause of the stroke-like episodes remains speculative. The carbohydrate-deficient glycoprotein syndrome is an increasingly recognized multisystem disorder affecting hemostasis, and thus will involve clinical hematologists as part of a multidisciplinary team caring for patients with the syndrome.
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PMID:Coagulation abnormalities in the carbohydrate-deficient glycoprotein syndrome: case report and review of the literature. 988 8

Vascular occlusion has a central role in the pathophysiology of sickle cell disease (SCD) and, although there is little evidence that thrombosis alone is responsible, patients with sickle cell disease are known to have an ill-defined but increased thrombotic risk. The most serious complication of this in childhood is stroke which occurs in 7-10% of children and a further 14% have asymptomatic cerebrovascular disease (CVD) on imaging. We have performed a comprehensive profile of coagulation inhibitors and markers of thrombin generation in 96 children (83 nontransfused [NTx] and 13 transfused [Tx]) with steady-state SCD and 18 healthy sibling controls. The levels of protein S (free and total) and heparin cofactor II were reduced in both the NTx and Tx groups compared to controls and protein C and APC resistance ratios were reduced in the NTx group only. Antithrombin levels were not different from controls. Thrombin-antithrombin complexes and prothrombin fragment F1+2 were increased in both patient groups. In the NTx subgroups with or without CVD there were no differences for any of the parameters measured except for lower haemoglobin levels and higher white cell counts in those with asymptomatic CVD. We conclude that children with SCD have a reduction in levels of the majority of the coagulation inhibitors and increased thrombin generation in the steady-state and these are only partially reversed by transfusion. However, these abnormalities do not appear to play a primary role in the development of cerebrovascular disease.
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PMID:Prothrombotic changes in children with sickle cell disease: relationships to cerebrovascular disease and transfusion. 988 16


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