Association between tissue plasminogen activator and serum lipids in healthy volunteers

The statistical association between tissue plasminogen activator (t-PA) activity, antigen, plasminogen activator inhibitor-1 (PAI-1) antigen and lipids levels in blood samples used for medical check ups in 111 volunteers attending hospital for health examinations was examined. The t-PA activity level of 111 volunteers was 0.08-0.56 ng/ml (5% trimmed range) (normal range: 0.08-0.70 ng/ml); t-PA antigen concentrations were 2.4-9.2 ng/ml (normal range: 1.0-7.0 ng/ml); PAI-1 antigen concentrations were 5.2-57.4 ng/ml (normal range: 5.2-45.0 ng/ml). The volunteers with the lowest t-PA activity in blood (group E) had higher concentrations of serum total cholesterol (P less than 0.001), triglycerides (P less than 0.001), or t-PA antigen (P less than 0.001) and lower concentrations of high-density lipoprotein cholesterol (P less than 0.001) than those having normal serum lipids and t-PA activity level (group A). These results show that t-PA activity, antigen and PAI-1 antigen in blood obtained from the healthy volunteers are influenced significantly by the concentrations of lipids in blood.     

Plasminogen activator and plasminogen activator inhibitor activities in men with coronary artery disease

Although elevated levels of plasminogen activator inhibitor-1 (PAI-1) have been associated with the development of myocardial infarction, the correlation between the presence of coronary artery disease and increased levels of PAI-1 is controversial. The present study evaluated the association between angiographically-documented coronary artery disease and plasma levels of PAI-1 and tissue-type plasminogen activator (t-PA) in 65 men (ages 35 to 65 years) who had no previous history of myocardial infarction, angioplasty, or other medical illnesses. PAI-1 activity in these 65 patients was inversely correlated with t-PA activity, which was measured before and after venous occlusion. PAI-1 activity correlated positively with levels of triglycerides. There was a significant negative correlation between PAI-1 activity and levels of high-density lipoprotein. Each patient was placed in one of five groups according to the severity of coronary atherosclerosis, which ranged from normal vessels (group I) to greater than 50% occlusion of three vessels (group V). There were no significant differences among the five groups with respect to mean activity of PAI-1 (p = 0.98) or t-PA activity measured before venous occlusion (p = 0.22) or after occlusion (p = 0.70). T-PA and PAI-1 activities in these five groups were not different from those in 35 healthy men. These data indicate that there is no association between activities of PAI-1 or t-PA and coronary artery disease in this well-characterized male population.     

Bleeding diathesis due to decreased functional activity of type 1 plasminogen activator inhibitor.

We evaluated an elderly patient with a lifelong history of severe bleeding after surgery or trauma and with evidence of persistent hyperfibrinolysis. Routine coagulation studies were normal. Serum plasminogen (40%, normal 72-128%) and alpha 2-antiplasmin (55%, normal 70-145%) activities were decreased. Euglobulin clot lysis was abnormally shortened (50 min) and normalized in vitro with epsilon-aminocaproic acid (EACA). The patient was treated with EACA with prompt cessation of bleeding. Patient tissue-plasminogen activator (t-PA) levels in serum were normal (4.7 ng/ml, control 3.5-7.2) as detected by a two-site immunoradiometric assay (IRMA). Patient fibrinolytic inhibitor activities were assessed by incubating 125I-labeled t-PA with either whole blood or serum followed by SDS-PAGE and autoradiography to identify the resultant protease/protease inhibitor complexes. In comparison to blood samples obtained from normal donors, patient plasma and serum demonstrated reduced binding of a fast-acting plasminogen activator inhibitor to 125I-labeled t-PA. Immunoprecipitation experiments indicated diminished complex formation between type 1 plasminogen activator inhibitor (PAI-1) in patient serum and 125I-labeled t-PA. Low patient PAI-1 activity was confirmed in serum (0.36 U/ml, control 0.87-1.81; n = 3) and in platelet lysates using a functional IRMA to quantitate PAI-1 binding to immobilized t-PA. However, patient serum PAI-1 antigen was within the normal range when analyzed by IRMA (31.8 ng/ml, control 19.6-42.2); this result was confirmed in both serum and platelets by Western blot (n = 3). Mixing experiments using purified PAI-1 as well as patient and control sera did not show evidence for an inhibitor against PAI-1. We conclude that this patient's bleeding diathesis was due to hyperfibrinolysis and defective PAI-1. This patient provides the first demonstration of a link between decreased in vivo PAI-1 activity and disordered hemostasis, and supports a role for PAI-1 in control of vivo fibrinolysis.     

Fibrinolytic parameters and insulin resistance in young survivors of myocardial infarction with heterozygous familial hypercholesterolemia

A characteristic feature of patients with heterozygous familial hypercholesterolemia (FH) is the premature occurrence of coronary artery disease because of elevated LDL cholesterol levels. Hyperinsulinemia and insulin resistance, important characteristics of the cardiovascular dysmetabolic syndrome (CDS), were found to be associated with coronary artery disease in FH subjects, as in the general population. We investigated whether hypofibrinolysis, as part of CDS, is independently associated with symptomatic coronary artery disease in these high-risk patients. Clinical examination (body mass index, waist circumference, blood pressure) and blood analysis (plasma tissue plasminogen activator (t-PA) antigen, plasminogen activator inhibitor (PAI-1) antigen and activity, fibrinogen, serum lipids and lipoproteins, fasting glucose and insulin) were carried out in 39 male patients with heterozygous FH (aged 46.6 +/- 8.8 years). Insulin resistance was calculated using the homeostasis model assessment (HOMA) mathematical model. Thirteen of the patients had suffered a myocardial infarction (MI) 5 to 8 years ago (aged 47.8 +/- 6.1 years) and 26 were free of coronary artery disease (aged 45.9 +/- 9.9 years). There was no difference in total and LDL cholesterol between the two groups. Patients with previous myocardial infarction had significantly higher levels of insulin, insulin resistance, triglycerides, t-PA antigen, PAI-1 antigen and activity, and significantly lower values of HDL cholesterol. Other widely recognised risk factors for coronary artery disease, such as smoking, systolic and diastolic blood pressure, obesity and age, did not differ significantly between the groups. In the logistic regression model, PAI-1 antigen, as a marker of hypofibrinolysis, emerged as an independent risk factor for the occurrence of myocardial infarction (odds ratio 1.55; p = 0.02). In summary our results suggest that the impairment of fibrinolytic activity resulting from elevated levels of PAI-1 antigen and activity and t-PA antigen is an independent variable in CDS associated with the premature occurrence of myocardial infarction in male patients with FH.     

Modulation of sympathetic activity by tissue plasminogen activator is independent of plasminogen and urokinase

Sympathetic neurons synthesize, transport, and release tissue-type plasminogen activators (t-PAs) and urinary-type plasminogen activators (u-PAs). We reported that t-PA enhances sympathetic neurotransmission and exacerbates reperfusion arrhythmias. We have now assessed the role of u-PA and plasminogen. Neurogenic contractile responses to electrical field stimulation (EFS) were determined in vasa deferentia (VD) from mice lacking t-PA (t-PA(-/-)), plasminogen activator inhibitor-1 (PAI-1(-/-)), plasminogen (plgn(-/-)), u-PA (u-PA(-/-)), and wild-type (WT) controls. Similar levels of t-PA were present in VD and cardiac synaptosomes of WT, PAI-1(-/-), plgn(-/-), and u-PA(-/-) mice, whereas t-PA was undetectable in t-PA(-/-) tissues. EFS responses were potentiated and attenuated in VD from PAI-1(-/-) and t-PA(-/-) mice, respectively, but indistinguishable from WT responses in VD from plgn(-/-) and u-PA(-/-) mice. Moreover, t-PA inhibition with t-PA(stop) decreased EFS response in WT mice, whereas u-PA(stop) did not. VD responses to ATP, norepinephrine, and K(+) in t-PA(-/-), PAI-1(-/-), plgn(-/-), and u-PA(-/-) mice were similar to those in WT, whereas t-PA(stop) did not modify VD responses to norepinephrine in WT, t-PA(-/-), and PAI-1(-/-) mice, indicating a prejunctional site of action for t-PA-induced potentiation of sympathetic neurotransmission. Indeed, K(+)-induced norepinephrine exocytosis from cardiac synaptosomes was potentiated in PAI-1(-/-), attenuated in t-PA(-/-) and not different from WT in u-PA(-/-) and plgn(-/-) mice. Likewise, ATP exocytosis was decreased in t-PA(-/-) and attenuated by t-PA(stop) in WT mice. Thus, t-PA-induced enhancement of sympathetic neurotransmission is a prejunctional event associated with increased transmitter exocytosis and independent of u-PA and plasminogen availability. This novel t-PA action may be a potential therapeutic target in hyperadrenergic states.     

Peptide-mediated inactivation of recombinant and platelet plasminogen activator inhibitor-1 in vitro.

Plasminogen activator inhibitor-1 (PAI-1), the primary inhibitor of tissue-type plasminogen activator (t-PA) and urokinase plasminogen activator, is an important regulator of the blood fibrinolytic system. Elevated plasma levels of PAI-1 are associated with thrombosis, and high levels of PAI-1 within platelet-rich clots contribute to their resistance to lysis by t-PA. Consequently, strategies aimed at inhibition of PAI-1 may prove clinically useful. This study was designed to test the hypothesis that a 14-amino acid peptide, corresponding to the PAI-1 reactive center loop (residues 333-346), can rapidly inhibit PAI-1 function. PAI-1 (0.7 microM) was incubated with peptide (55 microM) at 37 degrees C. At timed intervals, residual PAI-1 activity was determined by addition of reaction mixture samples to t-PA and chromogenic substrate. The T1/2 of PAI-1 activity in the presence of peptide was 4 +/- 3 min compared to a control T1/2 of 98 +/- 18 min. The peptide also inhibited complex formation between PAI-1 and t-PA as demonstrated by SDS-PAGE analysis. However, the capacity of the peptide to inhibit PAI-1 bound to vitronectin, a plasma protein that stabilizes PAI-1 activity, was markedly attenuated. Finally, the peptide significantly enhanced in vitro lysis of platelet-rich clots and platelet-poor clots containing recombinant PAI-1. These results indicate that a 14-amino acid peptide can rapidly inactivate PAI-1 and accelerate fibrinolysis in vitro. These studies also demonstrate that PAI-1 function can be directly attenuated in a physiologic setting and suggest a novel approach for augmenting fibrinolysis in vivo.     

恶性肿瘤血液纤溶酶原激活剂与抑制剂检测的临床价值

目的探讨恶性肿瘤患者血液纤溶酶原激活剂与抑制剂检测的临床应用价值。方法检测156例恶性肿瘤患者血液纤溶酶原激活剂(t-PA)、纤溶酶原抑制剂(PAI-1)活性变化,对检测数据进行统计学分析。结果不同类型的恶性肿瘤患者t-PA及PAI-1与健康对照组比较差异有统计学意义(P<0.05)。应用全自动血凝仪底物发光法检测恶性肿瘤患者纤溶活性变化具有敏感性、特异性、准确性高的优点。结论检测t-PA及PAI-1活性变化,从而可判断恶性肿瘤细胞浸润、增殖、转移及出血?血栓形成的原因。     

Inflammation, thrombosis and atherosclerosis: results of the Glostrup study

Summary.  Inflammation and thrombosis are important mechanisms in cardiovascular disease, as illustrated by the consistent association between inflammatory and hemostatic variables and the risk of cardiovascular events in epidemiological studies. However, the relationship between plasma concentrations of inflammatory and hemostatic markers and the severity of atherosclerosis is not yet well studied. We have evaluated 325 men and 370 women of 60 years, participating in the Danish Glostrup study. We diagnosed atherosclerosis by ultrasonographic measurement of intima-media thickness (IMT) of the right carotid artery and the assessment of plaque occurrence. Plasma samples were analyzed for the concentration of C-reactive protein (CRP), fibrinogen, d -dimer, plasminogen activator inhibitor type-1 (PAI-1) antigen and activity, tissue-type plasminogen activator (t-PA) antigen and activity, factor VII (FVII) antigen, FVII coagulant activity (FVII:C) and activated FVII (FVIIa). DNA variations were determined for fibrinogen, PAI-1, t-PA, FVII, factor XIII and methylene tetrahydrofolate reductase (MTHFR). Subjects with high IMT (upper 10% of distribution, n  = 63) had higher CRP levels [2.2 mg L⁻¹ (SE 0.3)] than subjects with IMT in the lowest tertile ( n  = 217) [1.7 mg L⁻¹ (SE 0.1), P  = 0.04], whereas there was no association between the hemostatic variables and IMT. There was an association between fibrinogen and d -dimer concentrations and number of plaques ( P  < 0.01), whereas there were no associations between CRP and the other hemostatic variables and the number of plaques. Genetic variation in the t-PA and MTHFR gene was associated with IMT. In conclusion, in the Glostrup population study, thrombosis and inflammation are associated with the severity of atherosclerosis, as reflected by IMT and plaque occurrence.     

纤溶酶原激活物抑制剂-1的研究进展

纤溶酶原激活物抑制剂-1(plasminogen activator inhibitor 1,PAI-1)作为体内组织型纤溶酶原激活物(tissue-type plasminogen activator,t-PA)和尿激酶型纤溶酶原激活物(urokinase-type plasminogen activator,u-PA)的主要抑制剂,与动静脉血栓、出血和凝血异常、细胞迁移密切相关,进而引起缺血性脑卒中、冠心病、静脉血栓、肿瘤转移、出血、股骨头坏死、流产等一系列疾病的发生发展。同时,体内血浆PAI-1活性水平又受血脂、血糖等调节,进一步参与肥胖、糖尿病、高脂血症等疾病的进程,又影响着上述相关疾病的预后。     

Interaction between plasminogen activator inhibitor type 1 (PAI-1) bound to fibrin and either tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). Binding of t-PA/PAI-1 complexes to fibrin mediated by both the finger and the kringle-2 domain of t-PA.

Plasminogen activation is catalyzed both by tissue-type-(t-PA) and by urokinase-type plasminogen activator (u-PA). This reaction is controlled by plasminogen activator inhibitor type 1 (PAI-1) that is either present in plasma or bound to fibrin, present in a thrombus. We studied the mechanism of in vitro inhibition of both t-PA and u-PA activity by PAI-1 bound to fibrin. It is shown that activation of latent PAI-1 unmasks a specific fibrin-binding site that is distinct from its reactive site. This reactive site of activated PAI-1 bound to fibrin is fully exposed to form complexes with t-PA and u-PA, that are unable to activate plasminogen. Upon complex formation with either one of the plasminogen activators, PAI-1 apparently undergoes a conformational change and loses its affinity for fibrin. Consequently, complexes of u-PA and PAI-1 dissociate from the fibrin matrix and are encountered in the fluid phase. In contrast, t-PA/PAI-1 complexes remain bound to fibrin. By employing recombinant t-PA deletion-mutant proteins, that precisely lack domains involved in fibrin binding, we demonstrate that binding of t-PA/PAI-1 complexes is mediated by both the "finger" (F) and the "kringle-2" (K2) domain of t-PA. A model is proposed that explains inhibition of the fibrinolytic process, at the level of plasminogen activation by t-PA, directed by PAI-1 bound to fibrin. An implication of the proposed model is that t-PA/PAI-1 complexes and free t-PA compete for the same binding sites on fibrin.     

慢性心力衰竭患者血浆组织型纤溶酶原激活物和纤溶酶原激活物抑制物-1含量变化及其临床意义

目的　研究慢性心力衰竭 (CHF)患者血浆组织型纤溶酶原激活物 (t PA)和纤溶酶原激活物抑制物 1(PAI 1)含量的变化及其临床意义。方法　用酶联免疫吸附法 (ELISA)检测 6 0例CHF患者 (CHF组 )和 2 0例健康体检者 (正常对照组 )血浆t PA及PAI 1抗原含量。结果　CHF组血浆t PA和PAI 1平均含量都明显高于对照组 (P<0 .0 1)。CHF患者血浆PAI 1含量增高随心功能恶化而愈加明显。结论　CHF患者纤溶功能明显下降 ,可用血浆t PA、PAI 1含量作为判断病情的参考指标之一。     

纤溶酶相关蛋白在冠心病患者中的表达

目的:了解冠心病患者是否存在组织型纤溶酶原激活物(t-PA)及纤溶酶原激活抑制物Ⅰ(PAI-Ⅰ)功能紊乱,以及这两个指标与血脂、胰岛素抵抗的相关关系。方法:选择2004年1月至2006年1月于我院住院就诊的冠心病患者作为观察对象。按临床类型分为SAP组、UAP组、AMI组、OMI组,并设健康对照组。检测t-PA、PAI-Ⅰ、胰岛素敏感性指数(IAI)、胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)等指标。结果:(1)健康对照组t-PA高于各型冠心病组(P<0.05),AMI组t-PA低于其余各型冠心病组(P<0.05);健康对照组PAI-Ⅰ低于各型冠心病组(P<0.05),AMI组PAI-Ⅰ高于其余各型冠心病(P<0.05)。(2)t-PA与IAI呈正相关,与TC、TG、LDL呈负相关;PAI-Ⅰ则与IAI呈负相关,与TC、TG、LDL呈正相关。(3)各病例组t-PA于治疗后有所升高,PAI-Ⅰ于治疗后有所下降(P<0.05)。结论:冠心病患者存在明显的纤溶功能紊乱,且以急性期为重,并且纤溶功能紊乱与胰岛素抵抗、血脂异常等因素有关。     

Standardization of methods for measuring plasminogen activator inhibitor activity in human plasma

We have standardized the measurement of plasminogen activator inhibitor type 1 (PAI-1) activity in plasma. One-chain tissue-type plasminogen activator (t-PA; EC 3.4.21.31; final activity, 5 int. units/mL) was incubated with plasma (final dilutions 1:4 to 1:40) in phosphate buffer (pH 7.4, ionic strength = 0.15) for 15 min at 37 degrees C, followed by acidification and measurement of residual t-PA activity by an amidolytic method. The PAI-1 activity assay was 98% specific for PAI-1 activity in samples from both pregnancy and nonpregnancy, and varied linearly with added plasma volume when the percent inhibition of t-PA was between 8% and 50%. For the standardized method, analytical recovery was 93 +/- 5%, the detection limit was 1.6 arbitrary units per milliliter (1 arb. unit of PAI-1 activity = inhibition of 1 int. unit of t-PA activity), and total imprecision was 10.2 (SD 0.7) arb. units/mL (CV = 7%, n = 20). The average PAI-1 activity in 10 healthy individuals drawn between 0800 and 1000 hours was 23.9 +/- 15.4 arb. units/mL. Compared with the standardized assay, two of three previously described assays underestimated PAI-1 activity in plasma by 77% and 85%, respectively.     

Vascular and fibrinolytic effects of intra-arterial tumour necrosis factor-alpha in patients with coronary heart disease

Elevated plasma t-PA (tissue plasminogen activator) and serum CRP (C-reactive protein) concentrations are associated with an adverse cardiovascular risk. In the present study, we investigated whether acute local inflammation causes vascular dysfunction and influences t-PA release in patients with stable coronary heart disease. Serum CRP, plasma t-PA and PAI-1 (plasminogen activator inhibitor type 1) concentrations were determined in 95 patients with stable coronary heart disease. A representative subpopulation of 12 male patients received an intra-brachial infusion of TNF-alpha (tumour necrosis factor-alpha) and saline placebo using a randomized double-blind cross-over study design. Forearm blood flow and plasma fibrinolytic and inflammatory variables were measured. Serum CRP concentrations correlated with plasma t-PA concentrations (r=0.37, P<0.001) and t-PA/PAI-1 ratio (r=-0.21, P<0.05). Intra-arterial TNF-alpha caused a rise in t-PA concentrations (P<0.001) without affecting blood flow or PAI-1 concentrations. TNF-alpha pretreatment impaired acetylcholine- and sodium nitroprusside-induced vasodilatation (P<0.001 for both) whilst doubling bradykinin-induced t-PA release (P=0.006). In patients with stable coronary heart disease, plasma fibrinolytic factors correlate with a systemic inflammatory marker and local vascular inflammation directly impairs vasomotor function whilst enhancing endothelial t-PA release. We suggest that the adverse prognosis associated with elevated plasma t-PA concentrations relates to the underlying causative association with vascular inflammation and injury.     

Increased plasminogen activator inhibitor-1 activity in offspring of type 2 diabetic patients: lack of association with plasma insulin levels

OBJECTIVE: To determine whether a dysregulation of the fibrinolytic system exists in normal glucose tolerant offspring of type 2 diabetic patients. RESEARCH DESIGN AND METHODS: In this cross-sectional study, 32 offspring of type 2 diabetic patients and 26 subjects with no family history of diabetes were studied. With respect to the metabolic parameters, plasma fasting and 2-h postload (75 g glucose) glucose and insulin levels, total cholesterol, triglycerides, and HDL cholesterol concentrations were determined. To evaluate the status of hemostatic factors, fibrinogen, tissue plasminogen activator (tPA) antigen level, plasminogen activator inhibitor-1 (PAI-1) antigen level, and PAI-1 activity were assessed. The statistical analyses included the Mann-Whitney U test to check the significance of differences between variables in the two groups and Spearman's rank correlation tests to check the interrelationships between the hemostatic and metabolic parameters in the offspring group. RESULTS: All subjects had normal glucose tolerance according to the American Diabetes Association criteria. Plasma fasting and postload insulin concentrations were significantly higher in offspring compared with control group (P<0.00001 and P<0.01, respectively). Plasma fasting and postload glucose, fibrinogen, tPA antigen, total cholesterol, and BMI were comparable between the groups. The offspring had significantly higher waist-to-hip ratio (WHR) (P = 0.03), higher triglycerides (P = 0.01), and lower HDL cholesterol (P<0.01) compared with the control group. PAI-1 antigen level and PAI-1 activity were higher in the offspring (P = 0.05 and P = 0.04, respectively). In the offspring group, PAI-1 activity was correlated with plasma PAI-1 antigen level (r = 0.40, P = 0.02), fibrinogen (r = 0.45, P = 0.01), and HDL cholesterol (r = -0.36, P = 0.04). However, tPA antigen level, fasting and postload plasma glucose and insulin, total cholesterol, triglycerides, WHR, and BMI did not correlate with PAI-1 activity. CONCLUSIONS: These data suggest that normal glucose tolerant offspring of type 2 diabetic subjects have elevated PAI-1 activity indicating to hypofibrinolysis in this group. The elevated PAI-1 activity has no association with plasma insulin concentration.     

Ethnic differences in cardiovascular risk factors in healthy Caucasian and South Asian individuals with the metabolic syndrome

BACKGROUND: The metabolic syndrome is a cluster of atherothrombotic risk factors that are commonly associated with insulin resistance. OBJECTIVES: The aim of this study was to investigate ethnic differences in insulin resistance and non-traditional cardiovascular risk factors in relation to the International Diabetes Federation (IDF) definition of the metabolic syndrome. PATIENTS AND METHODS: A total of 245 healthy South Asians and 245 age- and sex-matched Caucasians were studied. C-reactive protein (CRP), complement C3, plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (t-PA) were measured and homeostasis model assessment-insulin resistance (HOMA-IR) was calculated from fasting plasma glucose and insulin levels. RESULTS: Fifty Caucasian (20%) and 95 (39%) South Asian subjects had the metabolic syndrome as defined by the IDF. In South Asian subjects, HOMA-IR, CRP, C3, PAI-1 and t-PA were significantly higher in subjects with the metabolic syndrome. In contrast, in Caucasian individuals there was no difference in HOMA-IR or C3 levels and only CRP, PAI-1 and t-PA were higher in subjects with the metabolic syndrome. In a logistic regression model, plasma levels of CRP and PAI-1 were independent predictors of the metabolic syndrome in Caucasians, whereas plasma levels of C3 and t-PA as well as HOMA-IR were independent predictors of the metabolic syndrome in South Asian subjects. CONCLUSIONS: In the cohort of individuals studied, the IDF definition of the metabolic syndrome was associated with insulin resistance in the South Asian but not the Caucasian population. This work also showed ethnic differences in non-traditional cardiovascular risk factors in the presence of the metabolic syndrome.     

Elevation of plasminogen activator inhibitor 1 in borderline hypertension is linked to concomitant metabolic disturbances

Abstract. In the present study we investigated plasma levels of plasminogen activator inhibitor 1 (PAI-1), fibrinogen and von Willebrand factor (vWF) in borderline hypertensive (BHT) men [diastolic blood pressure (DBP) 85–94 mmHg, n = 75] and age-matched normotensive (NT) control subjects (DBP ≤80 mmHg, n = 75), in relation to smoking, body mass index (BMI) and fasting lipoprotein and insulin levels. PAI-1 levels were elevated in the BHT group [16.3 vs. 13.7 arbitrary units (AU), P = 0.032], whereas levels of fibrinogen and vWF were similar in the two groups. The PAI-1 elevation was even more pronounced in dyslipidaemic BHT subjects than in normolipidaemic NT subjects (20.0 vs. 10.3 arbitrary units (AU), P = 0.001). PAI-1 levels showed strong correlations with insulin, lipoproteins and BMI ( P < 0.01-0.001), but not with DBP. The results show that disturbances in the fibrinolytic system appear even in borderline hypertension. The elevation of PAI-1 levels seems to be more strongly linked to concomitant metabolic disturbances than to blood pressure levels.     

Influence of thrombin-activatable fibrinolysis inhibitor and plasminogen activator inhibitor-1 gene polymorphisms on tissue-type plasminogen activator-induced recanalization in ischemic stroke patients

OBJECTIVE: Endogenous resistance to tissue-type plasminogen activator (t-PA) might decrease the benefit of thrombolysis-induced recanalization. Thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor-1 (PAI-1) are fibrinolysis inhibitors. TAFI removes residues from partially degraded fibrin that in turn eliminates plasminogen binding sites; PAI-1 directly inhibits the activity of t-PA. We aimed to study whether the presence of two common functional polymorphisms of the TAFI and PAI-1 genes influence rates of recanalization of the middle cerebral artery (MCA) among t-PA-treated stroke patients. METHODS AND RESULTS: TAFI and PAI-1 polymorphism determinations were performed by restriction fragment length polymorphism mapping and conventional sequencing in 139 patients with strokes involving the MCA and who received t-PA within 3 h. Recanalization was diagnosed by means of transcranial Doppler. No association was found between PAI-1 4 G/5 G polymorphism and recanalization rate. Dyslipidemia and TAFI Thr325Ile polymorphism were the main variables associated with recanalization resistance by the end of t-PA infusion: odds ratio (OR) 4.1 [95% confidence interval (95% CI) 1.6-10.8, P = 0.003] and OR 5.6 (95% CI 1.2-20, P = 0.031), respectively. The combination of the two polymorphisms doubled the risk of absence of recanalization: OR 11.1 (95% CI 1.4-89.8, P = 0.025). CONCLUSIONS: Polymorphic fibrinolysis inhibitor genes influence t-PA-induced recanalization resistance in ischemic stroke patients, especially when coexisting in the same patient. Efforts to individualize thrombolytic treatments are required.     

Effects of plasminogen activator inhibitor-1 on ischemic brain injury in permanent and thrombotic middle cerebral artery occlusion models in mice

BACKGROUND AND OBJECTIVES: Tissue plasminogen activator (t-PA) improves the outcome of ischemic stroke by recanalization of occluded vessels, but has neurotoxic side effects in experimental stroke models. Here, the effect of plasminogen activator inhibitor-1 (PAI-1), an endogenous inhibitor of t-PA, on ischemic infarct volume was studied. METHODS: After either permanent ligation or thrombotic occlusion of the middle cerebral artery (MCA), infarct volume, spontaneous reperfusion of thrombosed MCA, t-PA/PAI-1 complex level, and blood-brain barrier (BBB) permeability in the ischemic region was studied in transgenic mice with overexpression of PAI-1 and wild-type littermate controls and in mice with intracerebroventricular injection of human PAI-1. RESULTS: Infarct volume was smaller in PAI-1 transgenic mice (2.9 +/- 3.7 mm3, mean +/- SD) than in controls (8.9 +/- 5.0 mm3, P < 0.05) after permanent MCA ligation (plasma PAI-1 level 39 +/- 23 ng mL(-1) in transgenic mice vs. 1.5 +/- 0.6 ng mL(-1) in controls), whereas after MCA thrombosis it was larger in transgenics (13.1 +/- 3.1 mm3) than in controls (8.0 +/- 3.2 mm3, P < 0.05). Spontaneous reperfusion of the thrombosed MCA was significantly delayed in transgenic vs. control mice. In the ligation model, t-PA/PAI-1 complex levels were higher and BBB disruption was more pronounced in the ischemic region. Human PAI-1 injection reduced infarct volume by about 50% in wild-type mice but not in t-PA gene deficient mice. CONCLUSIONS: High PAI-1 levels reduced infarct volume in the permanent MCA ligation model, but enhanced it in the MCA thrombosis model.     

Positive impact of hormone replacement therapy on the fibrinolytic system: a long-term randomized controlled study in healthy postmenopausal women

Summary.  Background : The mechanisms by which postmenopausal hormone replacement therapy (HRT) may influence risk of cardiovascular disease are still unclear. Impaired fibrinolytic function is associated with an enhanced risk of cardiovascular disease and therefore the effect of HRT on fibrinolysis may be of importance. Objectives : To investigate the prolonged effect of HRT on the fibrinolytic system and to determine whether two common polymorphisms in the plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (t-PA) genes modulate this effect. Methods : Healthy postmenopausal women ( n  = 248) were randomized to HRT ( n  = 122) or no substitution ( n  = 126) 5 years prior to investigation. Results : Significantly higher values of t-PA activity and lower values of PAI-1 activity and PAI-1 antigen were found in the HRT group compared with the control group. This effect was independent of smoking and without influence from the two common polymorphisms PAI-1 −675(4G/5G) and t-PA intron8ins311. Furthermore, no difference between opposed estrogen (with norethisterone acetate as the gestagen component) and unopposed estrogen therapy was found. Both an intention-to-treat and a per-protocol analysis were performed and similar results were obtained. Conclusions : Long-term treatment with HRT in healthy postmenopausal women was found to be associated with a beneficial fibrinolytic profile. This effect was found independent of smoking status, opposed and unopposed estrogen therapy had equal effect, and no influence of the two common polymorphisms PAI-1–675(4G/5G) and t-PA intron8ins311 was found. This effect of HRT on fibrinolytic capacity may be one of the beneficial effects of HRT in relation to cardiovascular diseases.