Higher Plasminogen Activator Inhibitor-1 Activity Research Articles

Neutrophil-mediated Inflammatory Plasminogen Degradation, Rather Than High Plasminogen-Activator Inhibitor-1, May Underly Failures and Inefficiencies of Intrapleural Fibrinolysis

Complex pleural space infections often require treatment with multiple doses of intrapleural tissue plasminogen activator (tPA) and deoxyribonuclease, with treatment failure frequently necessitating surgery. Pleural infections are rich in neutrophils, and neutrophil elastase degrades plasminogen, the target substrate of tPA, that is required to generate fibrinolysis. We hypothesized that pleural fluid from patients with pleural space infection would show high elastase activity, evidence of inflammatory plasminogen degradation, and low fibrinolytic potential in response to tPA that could be rescued with plasminogen supplementation. Does neutrophil elastase degradation of plasminogen contribute to intrapleural fibrinolytic failure? We obtained infected pleural fluid and circulating plasma from hospitalized adults (n= 10) with institutional review board approval from a randomized trial evaluating intrapleural fibrinolytics vssurgery for initial management of pleural space infection. Samples were collected before the intervention and on days 1, 2, and 3 after the intervention. Activity assays, enzyme-linked immunosorbent assays, and Western blot analysis were performed, and turbidimetric measurements of fibrinolysis were obtained from pleural fluid with and without exogenous plasminogen supplementation. Results are reported as median (interquartile range) or number (percentage) as appropriate, with an α value of .05. Pleural fluid elastase activity was more than fourfold higher (P= .02) and plasminogen antigen levels were more than threefold lower (P= .04) than their corresponding plasma values. Pleural fluid Western blot analysis demonstrated abundant plasminogen degradation fragments consistent with elastase degradation patterns. We found that plasminogen activator inhibitor 1 (PAI-1), the native tPA inhibitor, showed high antigen levels before the intervention, but the overwhelming majority of this PAI-1 (82%) was not active (P= .003), and all PAI-1 activity was lost by day 2 after the intervention in patients receiving intrapleural tPA and deoxyribonuclease. Finally, using turbidity clot lysis assays, we found that the pleural fluid of 9 of 10 patients was unable to generate a significant fibrinolytic response when challenged with tPA and that plasminogen supplementation rescued fibrinolysis in all patients. Our findings suggest that inflammatory plasminogen deficiency, not high PAI-1 activity, is a significant contributor to intrapleural fibrinolytic failure. ClinicalTrials.gov; No.: NCT03583931; URL: www. gov.

Effects of urokinase type plasminogen activator and plasminogen activator inhibitor-1 expressions on the formation of aneurysm of perimembranous ventricular septal defect

The exact mechanisms of defect closure in patients with perimembranous ventricular septal defect (PMVSD) remain unknown. We hypothesized that the expression of urokinase type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) may mediate extracellular matrix (ECM) remodeling in aneurysms. Seven normal heart tricuspid septal leaflet and 33 aneurysms were collected in Shanghai Renji Hospital and Shanghai Children's Medical Center from January 2008 to June 2010. Immunohistochemical expression of uPA and PAI-1 in 4 normal heart valvular tissues and 15 aneurysms was detected with immunohistochemical methods. The expression of uPA and PAI-1 mRNA in 3 normal heart valvular tissues and 7 aneurysms was studied by real time fluorescent PCR; the protein expression of uPA and PAI-1 in 4 normal heart valvular tissues and 11 aneurysms was tested with Western blotting. The surface of the aneurysms were completely covered by endothelial cells. Two types of granulation tissue, myxoid and fibrous, were associated with the aneurismal formation. uPA were recognized predominantly in valvar interstitial cells (VICs) which located mainly in regions adjacent to the endothelium and smooth muscle cells of blood vessels. PAI-1 was found in both VICs which located mainly in granulation tissue and endothelial cells. Nine aneurysms expressed a higher uPA activity than 4 normal valvular tissues ((74.6±11.8)% vs. (49.5±7.4)%; t = 3.87, P = 0.003) and six aneurysms expressed a low uPA activity ((10.3±3.1)% vs. (49.5±7.4)%; t=11.78, P=0.000) and a high PAI-1 activity ((55.2±1.7)% vs. (50.8±3.8)%; t=2.55, P=0.034) using immunohistochemical methods. uPA / PAI-1 ratio of protein expression tested by Western blot was 0.88±0.22 in four normal heart vavular tissues; five aneurysms expressed high uPA activity and low PAI-1 activity and uPA/PAI-1 ratio was 4.26±2.04; while the other 6 cases expressed low uPA activity and high PAI-1 activity and uPA/PAI-1 ratio was 0.30±0.07; the difference among the three groups was statistically significant (P<0.05). The rate of uPA/PAI-1 in relative copy of mRNA expression among normal heart valvular tissue, high uPA expressed aneurysms and low uPA expressed aneurysms are also significantly different (2.14±0.17 vs. 0.45±0.04; 2.14±0.17 vs. 4.38±1.41, P<0.05) respectively. The expression of uPA and PAI-1 in VICs suggests that interactions among these molecules contribute to the aneurysm formation and development. This provides a potential mechanism for defect closure in patients with PMVSD.

Abstract T P75: Temporal Profiles of Plasminogen Activator Inhibitor-1 Concentration and Activity Changes in Circulation after Focal Stroke and Tissue Type Plasminogen Activator Administration in Rats

Aims: Plasminogen activator inhibitor-1 (PAI-1) is the main and potent endogenous tissue-type plasminogen activator (tPA) inhibitor, but an important question on whether PAI-1 in blood stream responds and interferes with the exogenously administered tPA remains unexplored. We for the first time investigated temporal profiles of PAI-1 concentration and activity in circulation after stroke and tPA administration in rats. Methods: Permanent MCAO focal stroke of rats were treated with saline or 10mg/kg tPA at 3 hours after stroke (n=10 per group). Plasma (platelet free) PAI-1 antigen and activity levels were measured by ELISA at before stroke, 3, 4.5 (1.5 hours after saline or tPA treatments) and 24 hours after stroke. Since vascular endothelial cells and platelets are two major cellular sources for PAI-1 in circulation, we measured releases of PAI-1 from cultured endothelial cells and isolated platelets after direct tPA (4 μg/ml) exposures for 60 min in vitro by ELISA (n=4 per group). Results: At 3 hours after stroke, both plasma PAI-1 antigen and activity were significantly increased (3.09±0.67, and 3.42±0.57 fold of before stroke baseline, respectively, all data are expressed as mean±SE). At 4.5 hours after stroke, intravenous tPA administration significantly further elevated PAI-1 antigen levels (5.26±1.24), while as expected that tPA neutralized most elevated PAI-1 activity (0.33±0.05). At 24 hours after stroke, PAI-1 antigen levels returned to the before baseline level, however, there was a significantly higher PAI-1 activity (2.51±0.53) in tPA treated rats. In vitro tPA exposures significantly increased PAI-1 releases into culture medium in cultured endothelial cells (1.65±0.08) and platelets (2.02±0.17). Conclution: Our experimental results suggest that tPA administration may further elevate stroke-increased blood PAI-1 concentration, but also increase PAI-1 activity at late 24 hours after stroke. The increased PAI-1 releases after tPA exposures in vitro suggest tPA may directly stimulate PAI-1 secretions from vascular walls and circulation platelets, which partially contributes to the PAI-1 elevation observed in focal stroke rats. The underlying regulation mechanisms and pathological consequence need further investigation.

Association between 4G/4G plasminogen activator inhibitor-1 polymorphism, PAI-1 activity, and diabetic retinopathy

Background Plasminogen activator inhibitor-1 (PAI-1) is a key regulator of fibrinolysis; however, the relationship between PAI-1 and the most common diabetic microvascular complication, retinopathy, is unclear. Objectives To examine the association between the 4G/4G polymorphism of the PAI-1 gene with diabetic retinopathy (DR) as well as with the plasma levels of the PAI-1 enzyme among Egyptian patients. Participants and methods Thirty-three patients who had type 2 diabetes for more than 10 years were compared with 63 patients with proliferative diabetic retinopathy (PDR). Both groups were compared with 48 control individuals. All groups were matched for age and sex. PAI-1 4G/5G genotyping was carried out by a PCR and the PAI-1 levels were measured by enzyme-linked immunosorbent assay testing. Results Higher plasma PAI-1 activity was associated with a higher risk of DR. The overall frequency of the 4G allele was 54.54% among type 2 diabetes patients versus 78.79% among PDR patients (P Conclusion The PAI-1 gene polymorphism 4G/4G contributed to the genetic susceptibility to DR and a higher PAI-1 plasma level was independently associated with a higher risk of retinopathy among Egyptians.

Fibrinolytic Activity and Platelet Function in Subjects with Obstructive Sleep Apnoea and a Patent Foramen Ovale: Is There an Option for Prevention of Ischaemic Stroke?

Obstructive sleep apnoea (OSA) carries an increased risk of ischaemic stroke, but the underlying mechanism is not clear. As right-to-left shunting can occur through a patent foramen ovale (PFO) during periods of apnoea, we investigated nocturnal changes in fibrinolytic activity and platelet function in subjects who had OSA with or without PFO and in controls. We determined plasminogen activator inhibitor 1 (PAI-1) activity and antigen and platelet activation parameters. The severity of OSA was verified by polygraphy and PFO was detected by ear oximetry. We found a higher PAI-1 activity and antigen and a lower ratio of 2,3-dinor-PGF1α to 2,3-dinor-TXB2 in the subjects with OSA than in the controls. Linear regression analysis showed the apnoea-hypopnoea index (β-coefficient, 0.499; P = 0.032) and PFO (β-coefficient, 0.594; P = 0.015) to be associated independently with PAI-1 activity in the morning, while the increment in PAI-1:Ag from evening to morning was significantly associated with the presence of PFO (rs = 0.563, P = 0.002). Both OSA and PFO reduce fibrinolytic activity during nocturnal sleep. We hypothesize that subjects having both OSA and PFO may develop a more severe prothrombotic state during sleep than those having either OSA or PFO alone.

Elevated levels of PAI‐1 activity and t‐PA antigen are associated with newly diagnosed abnormal glucose regulation in patients with ST‐elevation myocardial infarction

Both Type 2 diabetes and cardiovascular disease have been associated with enhanced coagulation and suppressed fibrinolysis. To investigate a possible relationship between selected hemostatic variables and abnormal glucose regulation (AGR) in patients with acute ST-elevation myocardial infarction (STEMI) without known diabetes and to study changes in selected hemostatic variables from baseline to follow-up in STEMI patients with or without AGR. Plasminogen activator inhibitor-1 (PAI-1) activity, tissue plasminogen activator (t-PA) antigen, prothrombin fragment 1+2 (F(1+2)) and von Willebrand factor (vWF) were measured in fasting blood samples from 199 STEMI patients 16.5 h (median time) after admission and 3 months later. All patients were classified into normal glucose regulation (NGR) or AGR based on an oral glucose tolerance test at follow-up, according to the WHO criteria. High PAI-1 activity (≥ 75th percentile) measured in-hospital was associated with AGR (n = 49) with an adjusted odds ratio of 2.2 (95% confidence interval, 1.1, 4.4). In addition, high levels of t-PA antigen (≥ 75th percentile) were associated with AGR (adjusted odds ratio, 3.5; 95% confidence inteval, 1.5, 8.2), but only in men. Changes in the levels of F(1+2) were significantly more pronounced in patients with AGR compared with NGR (adjusted P = 0.04). Elevated levels of PAI-1 activity and t-PA antigen measured in-hospital in STEMI patients were associated with AGR classified at 3-month follow-up. Additionally, changes in the levels of F(1+2) were more pronounced in patients with AGR compared with NGR. The data suggest an enhanced prothrombotic state after an acute STEMI in patients with AGR without known diabetes.

Coagulation and Fibrinolytic Disturbances in Women with Polycystic Ovary Syndrome

Studies of fibrinolysis/coagulation status in women with polycystic ovary syndrome (PCOS) are contradictory. The aim of the study was to investigate whether women with PCOS have disturbed circulating levels of fibrinolysis/coagulation markers and, if so, whether the disturbances are related to hemodynamics, metabolic variables, sex steroids, SHBG, lipids, and inflammatory variables in women with PCOS. DESIGN/MAIN OUTCOME MEASURES: Anthropometric variables, hemodynamics, circulating hemostatic and inflammatory markers, and serum lipid profile were measured in women with untreated PCOS (n = 74) and controls (n = 31). After adjustments for age and body mass index (BMI), circulating plasminogen activator inhibitor 1 (PAI-1) activity and fibrinogen levels were higher in women with PCOS than controls; lipid profile, blood pressure, and levels of D-dimer, von Willebrand factor, factor VIII, tissue plasminogen activator, and inflammatory markers were comparable in the two groups. In multiple linear regression analyses including women with PCOS, low SHBG and high insulin predicted high PAI-1 activity (R(2) = 0.526; P < 0.001); elevated high-sensitivity C-reactive protein and soluble E-selectin in combination with heart rate predicted high fibrinogen (R(2) = 0.333; P < 0.001). Differences in PAI-1 activity were not significant after adjustments for age, BMI, SHBG, and insulin. PCOS is characterized by a prothrombotic state, as reflected by increased PAI-1 activity and fibrinogen, without signs of dyslipidemia or a proinflammatory state. Low SHBG and high insulin may partly explain the BMI-independent difference in PAI-1 activity between women with PCOS and controls. High-sensitivity C-reactive protein and E-selectin may be involved in regulating fibrinogen in PCOS.

Sex-related differences in the associations between hyperleptinemia, insulin resistance and dysfibrinolysis

The adipocyte-derived hormone leptin is associated with insulin resistance and reduced fibrinolytic status--or dysfibrinolysis--in humans. As leptin associates differentially to the development of cardiovascular disease and diabetes in men and women, we hypothesized that leptin and insulin sensitivity are related to dysfibrinolysis in a sex-dependent manner. Thirty-two men and 40 women were recruited from the Monitoring of trends and determinants in Cardiovascular disease (MONICA) population sample, representing the highest and lowest quartiles of fasting insulin levels. Lipids, fibrinolytic status [plasminogen activator inhibitor 1 (PAI-1) activity, tissue plasminogen activator (tPA) mass and activity, and tPA-PAI complex], leptin, testosterone and sex-hormone-binding globulin were measured. Insulin sensitivity was estimated using the euglycaemic clamp technique. Body composition was determined by bioimpedance. Determinants for circulating levels of fibrinolytic factors were explored in a multivariate linear regression analysis. Levels of fibrinolytic variables and estimated insulin sensitivity did not differ between men and women. Leptin was independently associated with reduced fibrinolytic status (high PAI-1 activity, low tPA activity, high tPA mass, and high tPA-PAI complex) in men (P < 0.001-0.002). In women, fat mass and/or insulin sensitivity were related to these factors (P < 0.001-0.03), and leptin only to reduced tPA activity (P = 0.002). Hyperleptinemia, dysfibrinolysis, insulin sensitivity and androgenicity associate differentially in men and women.

Human Seminal Plasma Fibrinolytic Activity

The distribution of total fibrinolytic activity in seminal plasma, as well as specific tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), and plasminogen activator inhibitor (PAI), has been studied using antigen and activity techniques in 170 ejaculates of men attending for assessment because of infertility without genital urinary pathology. Among these 170 patients, 18 showed oligoasthenoteratospermia, 28 showed azoospermia, and 124 showed normozoospermia. The seminal values were 50 times higher (262 to 289 ng/mL in antigen and 179 to 199 x 10 (3) IU/L for activity) than values in blood for t-PA and 15 times higher than values in blood for u-PA (18.4 to 26 ng/mL and 1.5 to 2.4 IU/mL, respectively). There was no correlation between the two levels in antigen or activity, but a higher concentration was observed in all first fractions from split ejaculates measurements. Moreover, t-PA was significantly lower in semen with abnormal liquefaction compared with semen exhibiting normal liquefaction. Zymography confirms the active forms. PAI was absent or at the detection limit for normozoospermia, whereas patients with oligoasthenoteratospermia or azoospermia showed high PAI antigen and activity levels. These data demonstrate that seminal PA activity may be related to sperm fertilizing capacity.

4G/5G PAI-1 promoter polymorphism and acute-phase levels of PAI-1 following coronary bypass surgery: a prospective study.

The 4G/5G plasminogen activator inhibitor-1 (PAI-1) promoter polymorphism has been associated with basal PAI-1 levels, with ischemic heart disease, and with adverse prognosis in critically ill patients. We hypothesized it might also influence the acute-phase levels of PAI-1 following coronary bypass surgery. In 111 consecutive patients undergoing elective coronary bypass surgery, 4G/5G genotyping and serial plasma PAI-1 activity and antigen levels were prospectively measured before surgery, daily up to 72 h, and at discharge. The inflammatory reaction was additionally assessed by white cell count, fibrinogen, interleukin-6, and C-reactive protein levels. PAI-1 activity and antigen concentrations increased approximately two-fold after surgery, peaking at 48 hours. Carriers of the 4G-allele, compared with 5G/5G homozygotes, showed approximately 20% higher PAI-1 activity and antigen both preoperatively ( P = 0.007 and P = 0.035) and after surgery. White cell count, fibrinogen, interleukin-6, and C-reactive protein values did not differ significantly according to genotypic groups. In multivariate analysis, the 4G/5G genotype was the only significant modulator of postoperative PAI-1 activity (P = 0.003) and the main significant modulator of postoperative PAI-1 antigen (P = 0.013). No significant interaction was found between the effects of time and genotype on postoperative PAI-1. This indicates that the association between 4G/5G and acute-phase PAI-1 levels is secondary to the genotype-related difference of baseline PAI-1. Postoperative PAI-1 concentrations of patients undergoing elective coronary bypass surgery are higher in carriers of the 4G-allele than in 5G/5G homozygotes as a result of higher baseline values. Knowledge of 4G/5G status may be useful to predict acute-phase PAI-1 concentrations.

Increased Plasminogen Activator Inhibitor-1 in Keloid Fibroblasts May Account for their Elevated Collagen Accumulation in Fibrin Gel Cultures

Proteolytic degradation of the provisional fibrin matrix and subsequent substitution by fibroblast-produced collagen are essential features of injury repair. Immunohistochemical studies revealed that although dermal fibroblasts of normal scars and keloids expressed both urokinase type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1), keloid fibroblasts had a much higher PAI-1 expression. In long-term three-dimensional fibrin gel cultures (the in vitro fibroplasia model), normal fibroblasts expressed moderate and modulated activity levels of uPA and PAI-1. In contrast, keloid fibroblasts expressed a persistently high level of PAI-1 and a low level of uPA. The high PAI-1 activity of keloid fibroblasts correlated with their elevated collagen accumulation in fibrin gel cultures. Substituting collagen for fibrin in the gel matrix resulted in increased uPA activity and reduced collagen accumulation of keloid fibroblasts. Furthermore, decreasing PAI-1 activity of keloid fibroblasts in fibrin gel cultures with anti-PAI-1-neutralizing antibodies also resulted in a reduction in collagen accumulation by keloid fibroblasts. Cumulatively, these results suggest that PAI-1 overexpression is a consistent feature of keloid fibroblasts both in vitro and in vivo, and PAI-1 may play a causative role in elevated collagen accumulation of keloid fibroblasts.

High levels of tissue plasminogen activator (tPA) antigen precede the development of type 2 diabetes in a longitudinal population study. The Northern Sweden MONICA Study

BackgroundImpaired fibrinolysis is found in impaired glucose tolerance and type 2 diabetes, associated with components of the metabolic syndrome. There are no data concerning fibrinolysis in subjects with normal glucose tolerance that convert to diabetes.MethodsWe studied the activities of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) and the levels of tPA antigen (a marker of endothelial dysfunction) in 551 subjects with normal glucose tolerance in 1990 in relation to incident diabetes during nine years of follow-up.ResultsSubjects with diabetes at follow-up (n = 15) had significantly lower baseline tPA activity and higher PAI-1 activity and tPA antigen than non-converters. The risk of diabetes increased linearly across quartiles of PAI-activity (p = 0.007) and tPA antigen (p < 0.001) and decreased across quartiles of tPA activity (p = 0.026). The risk of diabetes with low tPA activity or high PAI-1 activity persisted after adjustment for age and sex but diminished to a non-significant level after further adjustments. The odds ratio of diabetes for high tPA antigen was 10.4 (95% confidence interval 2.7–40) adjusted for age and sex. After further adjustment for diastolic blood pressure, waist circumference, insulin, triglycerides, fasting and post load glucose the odds ratio was 6.5 (1.3–33, p = 0.024).ConclusionsImpaired fibrinolysis and endothelial dysfunction are evident in subjects with normal glucose tolerance who later develop diabetes. High tPA antigen is predictive of future diabetes independent from the metabolic syndrome.

Increased plasminogen activator inhibitor activity and diabetes predict subsequent coronary events in patients with angina pectoris

BACKGROUND. Plasminogen activator inhibitor (PAI) is a marker of recurrence of myocardial infarction. Diabetes mellitus is also an important risk factor of coronary artery disease, including myocardial infarction and angina pectoris.AIM. We examined baseline plasma PAI activity levels, clinical variables, and angiographic findings and assessed them as prospective values for subsequent coronary events, such as sudden death, nonfatal myocardial infarction and coronary revascularization by percutaneous transluminal coronary angioplasty or coronary artery bypass surgery during the follow-up period.METHODS. We conducted a prospective study for 4 years of 249 consecutive patients admitted with angina pectoris. Blood samples for PAI were drawn at discharge.RESULTS. In the multivariate Cox proportional hazard model, PAI activity and diabetes mellitus were significant and independent risk factors (the risk increased by 10% in those with a higher PAI concentration and by 70% in diabetic patients). Event-free survival was reduced by higher PAI activity (≥ 8.4 lU/mL) and the presence of diabetes. The patients with higher PAI activity and diabetes had a 4.2-fold risk in comparison with the patients with lower PAI activity and no diabetes. However, patients with lower PAI activity were less likely to have coronary events even when they had diabetes.CONCLUSIONS. Higher PAI activity and diabetes predict subsequent coronary events in patients with angina pectoris. Diabetes has less prognostic value for subsequent coronary events in patients with lower PAI activity.

Differential effects of enalapril and nitrendipine on the fibrinolytic system in essential hypertension

Background Impaired fibrinolysis is associated with thromboembolic complications in hypertensive patients. It has been reported that cardiovascular morbidity and mortality rates are high even after lowering the elevated blood pressure with antihypertensive drugs. The aim of this study was to assess the effect of clinically used dosages of enalapril and nitrendipine on the fibrinolytic system. Methods Tissue plasminogen activator antigen (tPA) and tissue plasminogen activator inhibitor-1 (PAI-1) activity were measured in 20 normotensive male subjects and 46 male patients with mild essential hypertension divided into 2 groups (22 patients treated with 5 to 10 mg enalapril once a day and 24 treated with 5 to 10 mg nitrendipine once a day) before and 3 months after drug administration. Plasma renin activity and norepinephrine concentration were also measured. Results There were no significant differences in basal characteristics between the 2 hypertensive groups. In both hypertensive groups, blood pressure was significantly reduced to a similar level after drug treatment. In the 2 hypertensive groups, plasma renin activity significantly increased after drug treatment; however, there were no significant changes in norepinephrine concentration. Before drug treatment, the 2 hypertensive groups had significantly higher tPA and higher PAI-1 activity than the normotensive subjects. In the enalapril group, there was no significant change in tPA although PAI-1 activity significantly decreased after drug treatment. In the nitrendipine group, there was no significant change in tPA although PAI-1 activity significantly increased after drug treatment. Conclusion Thus enalapril improved impaired fibrinolysis but nitrendipine further aggravated fibrinolysis in essential hypertension. Considering the effect of antihypertensive drugs on the fibrinolytic system, more effective and beneficial treatment of hypertensives, especially at a high risk for thrombus formation might be selected. (Am Heart J 1999;137:1094-9.)

The plasminogen activator system in women with polycystic ovary syndrome

Objective: To evaluate the plasminogen activator system in women with polycystic ovary syndrome (PCOS). Design: Case-control study. Setting: A district general hospital in the United Kingdom. Patient(s): Eleven women with PCOS and 12 controls. Intervention(s): Venipunctures for assays of the plasminogen activator system. Main Outcome Measure(s): Euglobulin clot lysis times, plasminogen activator inhibitor 1 (PAI-1) activity, fibrinogen, plasminogen, and alpha-2 antiplasmin concentrations in plasma. Result(s): Women with PCOS had a significantly longer euglobulin clot lysis time (mean ± SD, 389 ± 164 minutes vs. 220 ± 110 minutes), a higher PAI-1 activity (mean ± SD, 19.7 ± 12 arbitrary units (AU) per mL vs. 10.9 ± 7.9 AU/mL), and a higher fibrinogen level (mean ± SD, 4.02 ± 0.64 g/L vs. 3.15 ± 0.6 g/L) compared to controls. Conclusion(s): Women with the PCOS may have an imbalance in the plasminogen activator system that is tilted toward a reduced production of the proteolytic enzyme plasmin. Systemically, this may increase their risk of cardiovascular disease, but at cellular level in the ovaries, it may result in impaired follicular rupture and anovulation.

The increase of plasminogen activator inhibitor activity is associated with graft occlusion in patients undergoing aorto-coronary bypass surgery.

Early graft occlusion is a common complication in patients undergoing aorto-coronary bypass surgery. Both mechanical and haemostatic factors play a role in the pathogenesis of thrombotic occlusion. Several studies have demonstrated a relationship between fibrinolytic activity and venous or arterial thrombosis. We undertook this study to evaluate the possible contribution of the fibrinolytic system to postoperative occlusion in patients undergoing aorto-coronary bypass graft (CABG). A venous occlusion (VO) test was performed preoperatively in 82 patients undergoing revascularization procedures. Before and after VO the euglobulin fibrinolytic activity and tissue type plasminogen activator (t-PA) activity and antigen were measured. Plasminogen activator inhibitor (PAI) activity and antigen and fibrinogen were also assessed in the preocclusion sample. An angiography performed 10d postoperatively showed graft occlusion in 23% of patients. Patients with graft occlusion had significantly higher preoperative PAI activity than patients without occlusion (P < 0.001). Reduced fibrinolytic response and t-PA capacity was also observed in the group of patients with graft occlusion (P < 0.03 and P < 0.02 respectively). We found a reduced preoperative fibrinolytic response, mainly related to high plasma PAI activity in patients with postoperative graft occlusion. These results suggest that increased PAI activity might have a predictive value for early thrombosis in patients undergoing CABG.

Prospective Evaluation of the Prevalence of Haemostasis Abnormalities in Unexplained Primary Early Recurrent Miscarriages

The prevalence of haemostasis abnormalities was evaluated in 500 consecutive women with unexplained primary recurrent miscarriages. Two matched reference groups with no antecedent of miscarriage were studied: 100 healthy mothers and 50 childless women. In the prospective part of the study, we found 9.4% of the patients (95% C.I.: 6.8-12%) with an isolated factor XII deficiency, 7.4% of the patients (5.0-9.8%) with primary antiphopholipid antibodies, 47% of the patients (42.6-51.4%) with an insufficient response to the venous occlusion test and an isolated hypofibrinolysis was found in 42.6% (38.2-47%) of the patients (reference groups: respectively 0/150, 3/150, 2/150, p < 10(-3)). Willebrand disease, fibrinogen, deficiency, antithrombin, protein C or protein S deficiencies were not more frequent in recurrent aborters than in members of the reference groups. In the retrospective part of the study, cases of plasma resistance to activated protein C were not abnormally frequent. Patients had higher Willebrand factor antigen (vWF), tissue-type plasminogen activator antigen (t-PA), plasminogen activator inhibitor activity (PAI) and D-dimers (D-Di) than the reference women. Values of vWF, t-PA, PAI and D-Di were altogether correlated but were not related to C-reactive protein concentrations. Among patients, those with an antiphospholipid syndrome and those with an insufficient response to the venous occlusion test had higher vWF, t-PA, PAI and D-Di values than the patients with none of the haemostasis-related abnormalities. Thus, factor XII deficiency and hypofibrinolysis (mainly high PAI) are the most frequent haemostasis-related abnormalities found in unexplained primary recurrent aborters. In patients with antiphospholipid antibodies or hypofibrinolysis, there is a non-inflammatory ongoing chronic elevation of markers of endothelial stimulation associated with coagulation activation. This should allow to define subgroups of patients for future therapeutic trials.

The decrease of plasminogen activator inhibitor after normalization of triglycerides during treatment with fibrates

Impaired fibrinolysis due to a high level of plasminogen activator inhibitor-1 (PAI-1) has been reported in patients with hypertriglyceridemia. We studied the fibrinolytic effects of the hypolipemic drugs gemfibrozil and fenofibrate that mainly affect triglyceride-rich lipoproteins in 27 patients with severe hypertriglyceridemia (Fredrickson's type IV and V). After a wash-out period of 4 weeks the patients were ramdomly cross-treated with gemfibrozil (600 mg b.i.d.) and fenofibrate (250 mg daily), each time for 6 weeks. Tissue-type plasminogen activator (t-PA) antigen, t-PA activity, PAI-1 antigen, PAI activity and serum lipids were measured before and after the 6 weeks of either treatment. Basal levels of PAI-1 antigen and activity were very high and did not change after any treatment in the whole group of patients, while the mean triglyceride level decreased by 49% after gemfibrozil and by 39% after fenofibrate. However, a significant decrease in PAI-1 antigen was observed in a subgroup of 9 patients treated with gemfibrozil, in whom triglycerides decreased to or below 2.8 mmol/1. In all patients t-PA antigen decreased significantly after treatment with either drug, while t-PA activity decreased only after fenofibrate. It was concluded that almost normal values of triglycerides should be achieved during treatment with fibrates in order to decrease high PAI-1 antigen and activity levels. On the other hand, the decrease of t-PA antigen during fibrate treatment seems not to be associated with the degree of triglyceride-lowering effect of these drugs.

Effect of metoprolol on fibrinolytic activity in hypertensive patients with high plasminogen activator inhibitor activity

Aim of the study: to investigate the effect of metoprolol on plasminogen activator inhibitor-1 (PAI-1) activity, PAI-1 antigen, tissue plasminogen activator (t-PA) activity and t-PA antigen before and after venous occlusion for 10 min. Study design: 14 hypertensive patients with high PAI-1 activity level (PAI-1⩾10 U/ml) were treated in two 3-week periods with metoprolol succinate (95 mg/d) or placebo in a double blind cross-over study. All fibrinolytic variables were also examined after 3 months treatment with metoprolol. Results: venous occlusion gave a reduction in PAI-1 activity and increases in PAI-1 antigen, t-PA capacity and t-PA release, irrespective of drug treatment. No statistical significant differences between metoprolol and placebo were found for any of the fibrinolytic variables. Conclusion: in this study the selective (β-blocker metoprolol did not inhibit t-PA release after venous occlusion and had no influence on the measured fibrinolytic variables in hypertensive patients with high PAI-1 levels. This suggests that other mechanisms than fibrinolytic are responsible for the preventive action of metoprolol on cardiovascular morbidity and mortality.

Multicentre Evaluation of Commercial Kit Methods: Plasminogen Activator Inhibitor Activity

In order to study the analytical performance of different commercial kits for determination of plasminogen activator inhibitor (PAI) activity we distributed eight selected split samples to 11 European laboratories experienced with haemostasis testing. Three different laboratories were involved in the production of data from each of the commercial kits tested. A considerable variation of PAI activity results reported from the laboratories testing the same commercial kits was observed. The range of reported results could in individual samples exceed the median value indicating an interlaboratory variation of more than 100%. When we harmonized the results reported from different kits in different laboratories by means of an international standard from National Institute for Biological Standards and Control (NIBSC) we still observed that the results produced by some kits deviated systematically from results produced by other kits. Also, the harmonized results were used to estimate the overall coefficient of variation (CV) of PAI activity determined in various laboratories by different kits. We observed an inverse correlation between the PAI activity level and the CV with a CV of about 100% for low PAI activity levels and a CV of about 16% for high PAI activity levels. The high imprecision of the kits in the low concentration range of PAI activity indicates that unspecific factors in plasma may interfere with determination of active PAI. This was confirmed by the evaluation of the results from one of the plasma samples, which was PAI-1 depleted. The laboratories involved in the testing reported for this sample a mean value of 6.1 IU/ml.(ABSTRACT TRUNCATED AT 250 WORDS)