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

Circadian patterns of risk for cardiac events and their implications for prevention and treatment of cardiovascular conditions are discussed. Sympathovagal tone, a major biological determinant of circadian variation in cardiovascular function, is modulated through circadian patterns of sleep-wake activity. The influence of neurohumoral activity on cardiovascular function is manifested by 24-hour variability in heart rate, blood pressure, and vasomotor tone. Platelet aggregation and plasminogen-activator inhibitor-1 activity peak around the time of awakening. Conversely, endogenous plasminogen activator exhibits a nadir around the time of awakening. Studies of patterns of occurrence of cardiac disorders such as acute myocardial infarction, sudden cardiac death, stroke, and ventricular arrhythmia show an increased occurrence during the period surrounding awakening. These patterns are consistent with observed circadian patterns in cardiovascular function. Diabetes, left ventricular dysfunction, and congestive heart failure may contribute to alterations in patterns of occurrence of cardiac events. Factors such as race, sex, and age may lead to alterations in circadian variation in cardiovascular function. Unusual physical exertion, stress, and anger may act as triggers of an event at any time of day. The circadian patterns of cardiac events follow the natural fluctuations in endogenous physiological processes, with a vulnerable period consistently observed in the early morning; dynamic assessment of markers of cardiovascular function may assist in determining the extent of disease progression and in selecting cardiovascular therapies.
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PMID:Circadian variations in cardiovascular function and their relation to the occurrence and timing of cardiac events. 982 43

The thrombotic risk of carrying plasminogen activator inhibitor-1-675 4G allele was found to be controversial in previous studies. The aim of this study was to evaluate the possible effect of plasminogen activator inhibitor-1 4G/5G polymorphism in the pathogenesis of childhood stroke. The case-control study included 43 patients with cerebral infarct who were below the age of 18 years (range, 10 months to 18 years) and 113 healthy unrelated individuals without family histories of thrombosis. Plasminogen activator inhibitor-1 4G/5G polymorphism was analyzed according to a previously described method. There was no statistically significant difference in patient and control groups for the distribution of plasminogen activator inhibitor-1 4G/5G polymorphism (P = .75) (allele frequency 4G controls: 0.50; patients: 0.53). However, there was a significant difference for the factor V (FV) 1691 A mutation for both groups (P = .0007).
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PMID:Plasminogen activator inhibitor-1 4G/5G polymorphism in Turkish children with cerebral infarct and effect on factor V 1691 A mutation. 1133 66

Low fibrinolytic activity may increase the risk of thrombosis. Plasminogen activator inhibitor-1 (PAI-1) is an inhibitor of the fibrinolytic system. We examined the PAI-1 levels in patients with ischemic stroke. Plasma levels of PAI-1 were measured using enzyme-linked immunosorbent assay (ELISA) in 55 consecutive patients (age 60.2 +/- 11.4, 40 males and 15 females) with ischemic stroke. The PAI-1 assessments as well as neurological examinations using validated stroke scales were conducted at admission and 1 week, 1 month, and 3 months after stroke. Sex- and age-matched controls (+/- 4 years) underwent plasma PAI-1 measurement once. Etiology of the stroke was classified using the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. All pertinent stroke risk factors were recorded. All patients were contacted 3 years after stroke for recurrent vascular thrombotic disease. The plasma PAI-1 levels were 17.2 +/- 7.8 IU at admission, 11.2 +/- 9.2 IU at 1 week, 14.4 +/- 7.9 IU at 1 month, and 17.8 +/- 7.8 IU at 3 months among patients and 11.8 +/- 9.5 IU among controls (p values are < .002, .7, .12, and < .0005, respectively). As a rule, the neurological scores did not show a correlation to the PAI-1 levels. Presence of diabetes, hypertension, obesity, smoking, anticoagulant treatment, and sleep apnea did not affect the PAI-1 levels at any time point. Females had slightly higher PAI-1 levels. Age was a strong determinant for PAI-1 levels being higher in younger patients at every sampling time point (p values .02, .02, .02, and .03 respectively). The etiology of the ischemic stroke did not have an impact on PAI-1 levels. In 16 patients recurrent thrombosis had occurred. The high PAI-1 levels at admittance may reflect either an acute phase response or a chronic state. Normalized levels at 1 week and 1 month may be due to hospital diet, antithrombotic medication, weight loss, active physical therapy, and better care for diabetes. PAI-1 levels at 3 months after stroke did not predict recurrent thrombosis.
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PMID:Plasminogen activator inhibitor-1 in patients with ischemic stroke. 1145 24

To investigate gender differences in conventional, coagulation and fibrinolytic factors in South Asian ischaemic stroke patients, we compared these variables in 50 South Asian females (SAFP) with 90 South Asian males (SAMP) with ischaemic stroke and in 52 females (SAFC) and 38 males (SAMC) without stroke. Plasminogen activator inhibitor-1 (PAI-1) antigen levels were significantly higher in SAFP compared with SAMP (18.2 vs. 13.3 U/ml, P = 0.04) even after adjustment for known covariates, but there was no difference in PAI-1 antigen levels between males and females in the control group. South Asian females exhibited higher levels of factor VII antigen and FVII:C activity in both stroke patients (114 vs. 99% in males, P = 0.01; 116 versus 104% in males, P = 0.04) and controls (116 vs. 97% in males, P = 0.004; 115 vs. 93% in males, P = 0.01). There were no significant differences in the levels of fibrinogen (3.8 vs. 3.7 g/l), FXIIa (2.2 vs. 2.4 ng/ml), von Willebrand factor (1.8 vs. 1.9 IU/ml) and tissue plasminogen activator (11.4 vs. 12.0 ng/ml) in SAMP and SAFP respectively. These results suggest that South Asian females have increased FVII levels and that females with a history of ischaemic stroke have a decreased fibrinolytic potential in comparison with males.
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PMID:Decreased fibrinolytic potential in South Asian women with ischaemic cerebrovascular disease. 1147 61

High plasma plasminogen-activator inhibitor-1 (PAI-1) concentrations have been reported in coronary artery disease and stroke. We therefore, prospectively studied the association of PAI-1 with early target organ damage in patients with arterial hypertension has not been clearly established. We therefore investigated 136 subjects, 64 males and 72 females, mean age 50.0 +/- 12.3 years, with newly diagnosed essential hypertension who were free of cardiovascular events and were not receiving any antihypertensive medication. Plasma PAI-1 levels were measured by an ELISA method (STAGO). The study population was divided into two groups, group A with PAI-1 levels below 40 ng/mL and group B with more than 40 ng/mL. The left ventricular mass was calculated according to the formula of Devereux and was normalized by the individual's body surface area (LVM/BSA). Carotid intima-media thickness (IMT) was determined by ultrasonography. Microalbuminuria was assessed by an immunoturbidimetric method (SERA-PAK). Group A consisted of 89 individuals with hypertension (65.4%), 41 males and 48 females and group B of 47 individuals with hypertension (34.6%), 21 males and 26 females. Individuals in group B exhibited significantly higher LVM/BSA than individuals in group A (155.9 +/- 23.1 g/m2 vs. 129.7 +/- 32.2g/m2, respectively, p = 0.004) and increased IMT (0.97 +/- 0.20mm vs. 0.87 +/- 0.21 mm, respectively, p < 0.001). Microalbumin excretion rate was greater in group B than group A (70.9 +/- 84.4 mg/24 hrs vs. 20.9 +/- 45.1 mg/24 hrs, respectively, p = 0.002). In conclusion, elevated PAI-1 levels are associated with target organ damage in subjects with newly diagnosed arterial hypertension. Thus, it can be postulated that this fibrinolytic inhibitor may characterize hypertensives in the early stages of the atherothrombotic process.
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PMID:Increased plasma plasminogen activator inhibitor-1 levels: a possible marker of hypertensive target organ damage. 1259 20

Bax inhibitor-1 (BI-1) is an evolutionarily conserved endoplasmic reticulum (ER) protein that suppresses cell death in both animal and plant cells. We characterized mice in which the bi-1 gene was ablated. Cells from BI-1-deficient mice, including fibroblasts, hepatocytes, and neurons, display selective hypersensitivity to apoptosis induced by ER stress agents (thapsigargin, tunicamycin, brefeldin A), but not to stimulators of mitochondrial or TNF/Fas-death receptor apoptosis pathways. Conversely, BI-1 overexpression protects against apoptosis induced by ER stress. BI-1-mediated protection from apoptosis induced by ER stress correlated with inhibition of Bax activation and translocation to mitochondria, preservation of mitochondrial membrane potential, and suppression of caspase activation. BI-1 overexpression also reduces releasable Ca(2+) from the ER. In vivo, bi-1(-/-) mice exhibit increased sensitivity to tissue damage induced by stimuli that trigger ER stress, including stroke and tunicamycin injection. Thus, BI-1 regulates a cell death pathway important for cytopreservation during ER stress.
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PMID:BI-1 regulates an apoptosis pathway linked to endoplasmic reticulum stress. 1530 16

Astrocytes are thought to be critical to neurons' surviving damage caused by ischemic stroke or other injury. Plasminogen activator inhibitor-1 is one of the active soluble factors released by astrocytes and regulates plasminogen activator-plasmin proteolytic sequence in the CNS as a serpin. In this study, we show that plasminogen activator inhibitor-1 can promote neurite outgrowth and survival of rat pheochromocytoma cells in serum-deprived conditions, and that this neuroprotective activity is correlated with enhanced activation of both extracellular signal-regulated kinases following a direct phosphorylation of nerve growth factor receptor, Trk A, and of c-Jun. Our results suggest that plasminogen activator inhibitor-1 can act as a neurotrophic factor, protecting neurons from serum deprivation-induced neuron death not only by compensating for nerve growth factor functions, but also by activating the c-Jun/activating protein-1 pathway.
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PMID:Plasminogen activator inhibitor-1 aids nerve growth factor-induced differentiation and survival of pheochromocytoma cells by activating both the extracellular signal-regulated kinase and c-Jun pathways. 1667 72

Plasminogen activator inhibitor-1 (PAI-1) is a physiological inhibitor of urokinase (uPA), a serine protease known to promote cell migration and invasion. Intuitively, increased levels of PAI-1 should be beneficial in downregulating uPA activity, particularly in cancer. By contrast, in vivo, increased levels of PAI-1 are associated with a poor prognosis in breast cancer. This phenomenon is termed the "PAI-1 paradox". Many factors are responsible for the upregulation of PAI-1 in the tumor microenvironment. We hypothesize that there is a breast cancer predisposition to a more aggressive stage when PAI-1 is upregulated as a consequence of Metabolic Syndrome (MetS). MetS exerts a detrimental effect on the breast tumor microenvironment that supports cancer invasion. People with MetS have an increased risk of coronary heart disease, stroke, peripheral vascular disease and hyperinsulinemia. Recently, MetS has also been identified as a risk factor for breast cancer. We hypothesize the existence of the "PAI-1 cycle". Sustained by MetS, adipocytokines alter PAI-1 expression to promote angiogenesis, tumor-cell migration and procoagulant microparticle formation from endothelial cells, which generates thrombin and further propagates PAI-1 synthesis. All of these factors culminate in a chemotherapy-resistant breast tumor microenvironment. The PAI-1 cycle may partly explain the PAI-1 paradox. In this hypothesis paper, we will discuss further how MetS upregulates PAI-1 and how an increased level of PAI-1 can be linked to a poor prognosis.
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PMID:Breast cancer and metabolic syndrome linked through the plasminogen activator inhibitor-1 cycle. 1787 97

Plasminogen activator inhibitor-1 (PAI-1), a member of the serpin gene family, is the primary inhibitor of urokinase-type and tissue-type PAs. PAI-1 plays an important role in the process of peripheral tissue remodeling and fibrinolysis through the regulation of PA activity. This serpin is also produced in brain tissues and may regulate the neural protease sequence in the central nervous system (CNS), as it does in peripheral tissues. In fact, PAI-1 mRNA is up-regulated in mouse brain after stroke. The serpin activity of PAI-1 helps to prevent tissue-type PA-induced neuron death. However, we have previously found that PAI-1 has a novel biological function in the CNS: the contribution to survival of neurites on neurons. In neuronally differentiated rat pheochromocytoma (PC-12) cells, a deficiency of PAI-1 in vitro caused a significant reduction in Bcl-2 and Bcl-X(L) mRNAs and an increase in Bcl-X(S) and Bax mRNAs. The change in the balance between mRNA expressions of the anti- and pro-apoptotic Bcl-2 family proteins promoted the apoptotic sequence: caspase-3 activation, cytochrome c release from mitochondria and DNA fragmentation. Our results indicate that PAI-1 has an anti-apoptotic role in neurons. PAI-1 prevented the disintegration of the formed neuronal networks by maintaining or promoting neuroprotective signaling through the MAPK/ERK pathway, suggesting that the neuroprotective effect of PAI-1 is independent of its action as a protease inhibitor. This review discusses the neuroprotective effects of PAI-1 in vitro, together with the relevant data from other laboratories. Special emphasis is placed on its action on PC-12 cells.
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PMID:Anti-apoptotic roles of plasminogen activator inhibitor-1 as a neurotrophic factor in the central nervous system. 1913 24

Cardiovascular disease (CVD) is the number one cause of death in both adult men and women. It is evident that active inflammation in the coronary arteries remains a key factor in plaque instability and subsequent cardiovascular events. The current clinical dilemma is that inflammation can occur even in patients who are on statin therapy, as well as in patients with "normal" cholesterol levels. Because fully half of all patients with cardiovascular events have normal cholesterol levels, there is a need to re-evaluate the role of inflammatory factors and biomarkers to better identify patients at risk. Current risk factors include C-reactive protein, fibrinogen, and platelet activator inhibitor-1. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is another emerging risk factor. The weight of evidence suggests that this biomarker also promotes vascular inflammation. Patients with higher levels of Lp-PLA2 have higher rates of CVD and stroke. Measurement of Lp-PLA2 can improve the identification of people at increased risk for CVD, independent of cholesterol, or C-reactive protein level. Lp-PLA2 has been an innovative target of immunomodulation therapy, and clinical studies with specific inhibitors are in progress evaluating this approach for both atherosclerosis development and clinical event reduction.
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PMID:Lipoprotein-associated phospholipase A2: an independent predictor of cardiovascular risk and a novel target for immunomodulation therapy. 1969 Apr 73


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