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

The objective of this study was to investigate the effect of fibrinogen on lipopolysaccharide (LPS)-stimulated blood cells. To this end, a minimum essential blood system was established, reconstituted from washed blood cells and 20% (fibrinogen-free) lepirudin anticoagulated serum in RPMI-1640. Concurrent addition to the system of 1.0-4.0 mg/ml fibrinogen increased LPS-induced tissue factor (TF) activity in the monocytes in a dose-dependent manner. This enhancing effect was, by and large, independent of the LPS concentration (0.5-5.0 ng/ml). Even at the lowest concentration of fibrinogen (1.0 mg/ml), the enhancing effect was quite significant (46-80%) at almost every concentration of LPS tested. Furthermore, LPS-induced release of the two proinflammatory products tumor necrosis factor-alpha and interleukin-8 were also enhanced by added fibrinogen. In conclusion, fibrinogen is capable of enhancing the emergence of certain proinflammatory molecules as well as the procoagulant factor TF, effects that may very well in part be accountable for fibrinogen-related risk of ischemic heart disease and stroke.
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PMID:Fibrinogen increases lipopolysaccharide-induced tumor necrosis factor-alpha and interleukin-8 release, and enhances tissue factor activity in monocytes in a modified whole blood system. 1173 67

It is widely recognized that thrombosis is the major event in the evolution of acute myocardial infarction (AMI) and acute ischemic stroke (AIS). But the contribution of coagulation factors to the development of ischemic arterial diseases is still not clearly established. The goal of this study was to establish the possible relationship between coagulation factors as well as anticoagulant and the onset of AMI and AIS. The study population consisted of 69 patients with AMI and 71 with AIS as well as 50 age-matched healthy volunteers. Compared with the control group, plasma tissue factor (TF) and tissue factor pathway inhibitor (TFPI) activities and both TF and TFPI antigens were significantly higher in the AMI group; plasma TF activity and antigen in AIS group were significantly increased, but the activity and antigen of plasma TFPI were significantly decreased in the AIS group. Plasma FVII coagulation (FVII:C) activity was markedly higher in patients with AIS, but not statistically different to the control in patients with AMI. FVIII coagulation (FVIII:C) activity was remarkably higher in patients with AMI but slightly lower than the control in patients with AIS. In the AMI and AIS groups, prothrombin activity and clottable fibrinogen were significantly higher and plasma antithrombin III activity was remarkably lower than the control. The results suggested that during the onset of AMI and AIS, the initiation of TF pathway would be associated with the thrombotic events and that the blood be in hypercoagulable state. But the changes of FVII:C, TFPI and FVIII:C in AMI are different from those in AIS.
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PMID:Observation on tissue factor pathway and some other coagulation parameters during the onset of acute cerebrocardiac thrombotic diseases. 1247 82

The central event of the hemostatic process is the generation of thrombin through the tissue factor pathway. This is a highly regulated, dynamic process in which thrombin itself plays many roles, positively and negatively its production and destruction. The hemostatic process is essential to normal physiology and is also the Achilles heel of our aging population. The inappropriate generation of thrombin may lead to vascular occlusion with the consequence of myocardial infarction, stroke, pulmonary embolism, or venous thrombosis. In this review, we summarize our present views regarding the tissue factor pathway by which thrombin is generated and the roles played by extrinsic and intrinsic factor Xa generating complexes in hemostasis and the roles of the stoichiometric and dynamic inhibitors that regulate thrombin generation.
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PMID:The dynamics of thrombin formation. 1252 20

Patients with cerebral small vessel disease (SVD) can present as isolated lacunar infarction or with diffuse white matter changes, with the imaging appearance of leukoaraiosis. Endothelial dysfunction, which can lead to breakdown of the blood-brain barrier, impaired cerebral autoregulation and prothrombotic changes, is believed to be important in mediating disease. Circulating levels of intercellular adhesion molecule 1 (ICAM1), thrombomodulin (TM), tissue factor (TF) and tissue factor pathway inhibitor (TFPI) are markers of endothelial activation and damage, and may provide insights into disease pathogenesis or differences between phenotypes. We therefore measured these markers in a prospective series of patients with lacunar stroke. One hundred and ten white Caucasian patients with previous lacunar stroke and 50 community control subjects were studied. Markers of endothelial function were measured on venous blood samples. Patients were classified on brain imaging into two groups: isolated lacunar infarction (n = 47) and ischaemic leukoaraiosis, defined as a clinical lacunar stroke and leukoaraiosis on brain imaging (n = 63). The number of lacunes and severity of leukoaraiosis were also scored on MRI. ICAM1, TM and TFPI were elevated in cerebral SVD subjects compared with controls (P <or= 0.006). The ischaemic leukoaraiosis group had a different endothelial marker profile, with lower levels of TFPI (P = 0.01) and a higher TF/TFPI ratio (P = 0.01) compared with the isolated lacunar infarction group. TM levels were associated with the number of lacunes (P = 0.008) and the leukoaraiosis score (P = 0.03), but TF levels and the TF/TFPI ratio were associated only with the extent of leukoaraiosis (P <or= 0.02). These results suggest that there is evidence of chronic endothelial dysfunction in cerebral SVD, and endothelial prothrombotic changes may be important in mediating the ischaemic leukoaraiosis phenotype. Therapies which help to stabilize the endothelium may have a role in this group of patients.
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PMID:Markers of endothelial dysfunction in lacunar infarction and ischaemic leukoaraiosis. 1253 8

Increasing evidence points towards a prothrombotic state in atherosclerosis and its manifestations, such as peripheral artery disease (PAD), which is associated with thrombosis-related complications, such as acute limb ischaemia, graft thrombosis and stroke. We hypothesized that the increased risk of thrombogenesis in PAD may be related to abnormal angiogenesis and, thus, an increased risk of future vascular disease. To test this hypothesis, we measured plasma levels of tissue factor (TF) and related levels to indices of angiogenesis, that is vascular endothelial growth factor (VEGF) and its soluble receptor sFlt-1. We studied 234 patients (145 males; mean age 68.6+/-10 years) with proven PAD (ankle brachial pressure index <0.8) and compared them with 50 healthy controls. Levels of VEGF ( P =0.001) and TF ( P =0.043) were increased in patients compared with controls. There were significant correlations between VEGF and TF levels in both patients (Spearman r =0.351, P <0.001) and healthy controls (Spearman r =0.335, P =0.017). Amongst PAD patients, levels of VEGF were related to gender, with women having higher levels than men. There was no difference in the levels of sFlt-1 between the patients and controls, or between the subgroups of patients. There were however significant correlations between the levels of sFlt-1 and TF (Spearman r =0.268, P <0.001) and between sFlt-1 and VEGF (Spearman r =0.499, P <0.001). In conclusion, patients suffering from proven PAD have higher plasma levels of TF and VEGF compared with controls, with a significant correlation between the two. This suggests a link between the hypercoagulable state in PAD and the process of angiogenesis.
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PMID:Vascular endothelial growth factor and tissue factor in patients with established peripheral artery disease: a link between angiogenesis and thrombogenesis? 1265 84

The occurrence of cerebral or retinal ischemic symptoms ipsilateral to high-grade internal carotid artery (ICA) stenosis indicates a status of instability with a substantial risk for future major stroke. Additionally, the detection of microembolic signals downstream of ICA stenosis is predictive for future cerebral ischemia in asymptomatic and symptomatic patients. There is substantial evidence that in unstable ICA stenosis plaque rupture and thrombus formation are the most frequent pathoanatomic findings. In contrast, in nearly the half of unstable carotid plaques the lumen surface appears to be intact. Within plaque tissue, the unstable plaque is mainly characterized by a substantial amount of inflammatory cell (i. e. macrophages, T-cells) infiltration. These cells are mainly localized in the fibrous cap near the necrotic core. Produced by macrophages, matrix degrading enzymes (e. g. MMP-9) are overexpressed in the unstable ICA stenosis. Thrombogenicity is mainly determined by the local concentration of activated tissue factor, also expressed by inflammatory cells. Furthermore, a significantly higher rate of apoptotic smooth muscle cells can be found within the fibrous cap of instable carotid stenoses. Whether infection with Chlamydia pneumoniae contribute to instability is unlikely, because a positive association to clinical instability has not been shown up to now. The exact and detailed characterization of the unstable ICA plaque and the correlation of different biological mechanisms to clinical instability may offer the possibility to use it as a human model of unstable atherosclerosis in general and to test the efficacy of new developed anti-atherosclerotic pharmaceutical agents.
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PMID:[The unstable carotid stenosis: definition and biological processes]. 1273

Increasing evidence points toward a prothrombotic state in hypertension and atherosclerosis, conditions associated with thrombosis-related complications, such as myocardial infarction and stroke. We hypothesized that this increased risk of thrombogenesis may be related to endothelial damage/dysfunction and abnormal angiogenesis, and thus, an increased risk of future cardiovascular disease. Thrombogenesis, endothelial damage/dysfunction, and angiogenesis can be assessed by measurement of tissue factor (TF), von Willebrand Factor (vWF), flow-mediated dilatation (FMD), and vascular endothelial growth factor (VEGF), respectively. To test this hypothesis, we measured TF, vWF, FMD, and VEGF in 76 patients with systemic hypertension (71 men; mean age 64; mean blood pressure 167/72 mm Hg), considered additional risk factors such as diabetes, and related them to the patient's 10-year cardiovascular and cerebrovascular risk score using the Framingham equation. Patients were compared with 48 healthy normotensive controls. In these patients, the effects of 6 months of intensified blood pressure and (where appropriate) lipid-lowering treatment were investigated. In our patients, TF, VEGF, and vWF levels were higher, but FMD was lower (all p <0.001) compared with the controls. All markers correlated with each other and with both cardiovascular and cerebrovascular risk scores (all p <0.001). After intensified blood pressure and hypercholesterolemia treatment, total cholesterol, blood pressure, TF, VEGF, and vWF levels all decreased, whereas FMD increased (all p <0.001). Thus, in subjects with hypertension and other risk factors, endothelial damage/dysfunction (and thus, atherogenesis), thrombogenesis, and angiogenesis are abnormal, correlate with overall cardiovascular risk, and importantly, can be related to each other in a "Birmingham Vascular Triangle." Furthermore, these processes are beneficially affected by intensive blood pressure and lipid treatment.
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PMID:Relation of thrombogenesis in systemic hypertension to angiogenesis and endothelial damage/dysfunction (a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial [ASCOT]). 1291 69

Excessive coagulation and impaired fibrinolysis lead to many hemostatic disorders, which enhance the risk of development of life-threatening cardiovascular diseases such as myocardial infarction, stroke, deep venous thrombosis and pulmonary embolism, belonging to the most important factors influencing morbidity and mortality in civilized societies. The adverse events induced by currently used drugs, the need for regular monitoring of coagulation parameters, inconvenient, in some cases, route of administration stimulate further search for novel, effective and safe methods of therapies of these disorders. In this paper, we describe those new agents which are now under experimental and clinical study, such us prostanoids, nitroaspirin, GP IIb/IIIa receptor antagonists, thienopyridine derivatives, collagen-GPVI and von Willebrand factor-GPIb-IX contact blockers, direct thrombin inhibitors, inhibitors of thrombin-platelet interactions, factor VII inhibitors and tissue factor-factor VII contact blockers. Based on the available literature, we discuss the possible role of these agents in the future prevention and treatment of thromboembolic diseases.
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PMID:Progress in pharmacotherapy of thrombosis. 1458 10

Stroke is a heterogeneous disorder with significantly high morbidity and mortality. The relationship between serum cholesterol level and the incidence of stroke remains controversial. Recent evidence from primary and secondary prevention trials suggests that treatment with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors may reduce the incidence of stroke in patients with coronary artery disease (CAD). In this review, we attempt to outline and describe the potential mechanisms of HMG-CoA reductase inhibitors in the prevention of stroke. In addition to their lipid-lowering action HMG-CoA reductase inhibitors appear to exert their beneficial effects by various nonlipid-lowering mechanisms including anti-inflammatory effects, effect on endothelial function and coagulation cascade. Treatment with HMG-CoA reductase inhibitors is associated with decreased progression, plaque stablization and even regression of atheromatous plaque in the carotid arteries. HMG-CoA reductase inhibitors also inhibit the coagulation cascade at various levels such as activation of prothrombin, factor V, factor X and liberation of tissue factor in response to vascular injury. Inhibition of fibrinolysis occurs secondary to inhibition of plasmin generation. Pravastatin therapy is associated with a reduction in the size of aortic atheroma which is an independent risk factor for stroke. Lastly, left ventricular dysfunction after acute myocardial infarction is associated with an increased risk of stroke and HMG-CoA reductase inhibitors may indirectly decrease the incidence of stroke by reducing coronary events. Most of these effects are independent of the cholesterol-lowering effects of HMG-CoA reductase inhibitors. In conclusion, HMG-CoA reductase inhibitors may have a role in primary prevention of stroke in patients with CAD.
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PMID:How do HMG-CoA reductase inhibitors prevent stroke? 1472 94

Maintaining a delicate balance among anticoagulant, procoagulant, and fibrinolytic pathways in the cerebral microcirculation is of major importance for normal cerebral blood flow. Under physiological conditions and in the absence of provocative stimuli, the anticoagulant and fibrinolytic pathways prevail over procoagulant mechanisms. Blood clotting is essential to minimize bleeding and to achieve hemostasis; however, excessive clotting contributes to thrombosis and may predispose the brain to infarction and ischemic stroke. Conversely, excessive bleeding due to enhanced anticoagulatory and fibrinolytic mechanisms could predispose the brain to hemorrhagic stroke. Recent studies in the author's laboratory indicate that brain capillary endothelium in vivo produces thrombomodulin (TM), a key cofactor in the TM-protein C system that is of major biological significance to the antithrombotic properties of the blood-brain barrier (BBB). The BBB endothelium also expresses tissue plasminogen activator (tPA), a key protein in fibrinolysis, and its rapid inhibitor, plasminogen activator inhibitor (PAI-1). The procoagulant tissue factor is normally dormant at the BBB. There is a vast body of clinical evidence to document the importance of hemostasis in the pathophysiology of brain injury. In particular, functional changes caused by major stroke risk factors in the TM--protein C, tPA/PAI-1, and tissue factor systems at the BBB may result in large and debilitating infarctions following an ischemic insult. Thus, correcting this hemostatic imbalance could ameliorate drastic CBF reductions at the time of ischemic insult, ultimately resulting in brain protection. Delineation of the molecular mechanisms of BBB-mediated hemostasis will likely contribute to future stroke prevention efforts and brain protection strategies.
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PMID:Antithrombotic, procoagulant, and fibrinolytic mechanisms in cerebral circulation: implications for brain injury and protection. 1509 52


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