Plasminogen activator inhibitor-1 (PAI-1) promoter 4G/5G genotype and increased PAI-1 circulating levels in postmenopausal women with coronary artery disease

Increased circulating levels of type 1 plasminogen activator inhibitor (PAI-1) have been associated with coronary artery disease (CAD). However, genetic and environmental determinants of PAI-1 expression are only partially understood. The levels of PAI-1 have been found to relate to 4/5 guanosine (4G/5G) polymorphism in the promoter region of the PAI-1 gene. The 4G allele in this polymorphism has been associated with higher levels of plasma PAI-1 activity, but despite the strong correlation between PAI-1 activity and antigen, no association has been found between PAI-1 antigen levels and the PAI-1 promoter 4G/5G genotype. The aim of the present study was to analyze the influence of the PAI-1 promoter 4G/5G genotype on PAI-1 levels in post-menopause women with coronary disease in comparison with healthy women in pre and postmenopausal status, and the influence of this genotype on variations in PAI-1 levels after hormone replacement therapy (HRT). No differences between 4G/5G allele distribution in the groups studied were observed. The group of postmenopausal women with CAD showed significantly increased PAI-1 antigen and activity levels in comparison with the control groups, and the levels of PAI-1 correlated with the 4G/5G genotype. A multivariate analysis revealed that in the CAD group there was a high correlation between 4G allele dosage and PAI-1 antigen levels, which were also influenced by the triglyceride levels but not by estrogen or glucose levels. After hormone replacement therapy the decrease in PAI-1 levels was correlated with the 4G allele dosage. We conclude that in the group of postmenopausal women with CAD the influence of the PAI-1 promoter 4G/5G genotype on PAI-1 levels is more evident than in the control groups, and that the decrease in PAI-1 levels after HRT in CAD women correlates with the 4G allele dosage.     

Fluctuation of tPA and PAI-1 antigen levels in plasma: difference of their fluctuation patterns between male and female

The circadian fluctuation of the fibrinolytic activity and the antigen levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) in plasma were analyzed in normal male and female volunteers. Samples were obtained at 8:30, 10:30, 12:30, 14:30 and 16:30 h. Euglobulin clot lysis time (ECLT) showed the longest time at 8:30 to 10:30 h and the shortest time at 16:30 h. The highest level of tPA was obtained at 8:30 h and the lowest at 14:30 h in men, whereas the highest value was at 8:30 h and the lowest was at 16:30 h in females. Free PAI-1 showed highest value at 10:30 h in men and at 8:30 h in women. The lowest values obtained at 16:30 h in both men and women and were about one third of the highest values. ECLT was always shorter in females than in males and parameter such as tPA and PAI-1 were also lower in females than in males. The phase of the circadian rhythm of the fibrinolytic parameters may be advanced in females than in males.     

Fluctuation of TPA and PAI-1 antigen levels in plasma: difference of their fluctuation patterns between male and female

The daytime fluctuation of the fibrinolytic activity and the antigen levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) in plasma were analyzed in normal male and female volunteers. Samples were obtained at 8:30, 10:30, 12:30, 14:30 and 16:30 h. Euglobulin clot lysis time (ECLT) showed the longest time at 8:30 to 10:30 h and the shortest time at 16:30 h. The highest level of tPA was obtained at 8:30 h and the lowest at 14:30 h in men, whereas the highest value was at 8:30 h and the lowest was at 16:30 h in females. Active free PAI-1 showed highest value at 10:30 h in men and at 8:30 h in women. The lowest values obtained at 16:30 h in both men and women and were about one third of the highest values. ECLT was always shorter in females than in males and parameter such as tPA and PAI-1 were also lower in females than in males. The phase of the circadian rhythm of the fibrinolytic parameters may be advanced in females than in males.     

Retained fibrinolytic response and no coagulation activation after acute physical exercise in middle-aged women with previous myocardial infarction

Sudden physical exertion is associated with an increased risk of acute myocardial infarction (MI) and sudden cardiac death. In addition, activation of the coagulation cascade and/or reduced fibrinolytic capacity after physical exercise has been reported in patients with cardiovascular disease. We investigated the haemostatic responses to an acute submaximal physical exercise in middle-aged women with a history of MI compared with healthy, age-matched controls. Resting plasma von Willebrand factor antigen (vWF Ag) and tissue plasminogen activator (tPA) antigen concentrations and plasminogen activator inhibitor-1 (PAI-1) activity were higher in the patients compared with control subjects. After 30 min of submaximal exercise on a bicycle ergometer, small, but still significant, increases in fibrinogen and vWF Ag concentrations were found in both groups. However, exercise did not induce thrombin generation and fibrin formation, as assessed by thrombin–antithrombin complex and fibrin D-dimer, in either group. Both tPA antigen concentration and activity increased and PAI-1 activity decreased significantly with exercise in both groups. Interestingly, the magnitude of changes in these latter variables did not differ between the groups (P=.99, P=.88 and P=.24, respectively). The present study demonstrates that some middle-aged women with previous MI have no signs of coagulation activation and retained fibrinolytic response after submaximal exercise. The clinical implication of these results might be that women with stable coronary heart disease can participate in rehabilitative exercise training without exhibiting a procoagulative state.     

Short-term effect of surgical trauma on rat peritoneal fibrinolytic activity and its role in adhesion formation

BACKGROUND: Fibrin deposition, the primary step in the formation of post-surgical adhesions, is the result of a disbalance between the fibrin-forming and the fibrin-dissolving capacity of the peritoneum. Literature data suggest a transient reduction in local plasminogen activator activity after peritoneal trauma, which results in a reduction of fibrinolysis and permits deposited fibrin to become organized into fibrous, permanent adhesions. In the present study, the fibrinolytic parameters tissue-type plasminogen activator (tPA; antigen and activity) and plasminogen activator inhibitor type-1 (PAI-1; antigen and activity) were measured in peritoneal fluid, in peritoneal biopsies and in plasma to establish the time course of changes in fibrinolytic activity. DESIGN: A standardized peritoneal adhesion model in the rat. OUTCOME MEASURES: Analysis, over a 72-h period following surgical trauma. of the main fibrinolytic parameters in peritoneal lavage, in biopsies of damaged and undamaged peritoneum, and in plasma, and determination of fibrin and fibrin(ogen)-degradation products in peritoneal lavage fluid. RESULTS: At all time intervals, tPA antigen was found to be about six-fold increased in peritoneal lavage after surgical trauma. This significant rise in tPA antigen was accompanied by a large increase in its main inhibitor PAI-1, resulting in tPA activity levels similar to, or slightly higher than, those found in control animals. tPA activity was lowest at 4 h and increased thereafter. Also in biopsies from damaged peritoneum, tPA antigen was significantly increased. Tissue tPA activity was also lowest at 4 h, after which it increased, significantly so at 24 and 72 h. Similar, though smaller, changes were seen in the biopsies from undamaged areas of the peritoneal wall in operated rats. PAI-1 (antigen and activity) was not detected in peritoneal biopsies. Fibrin-related material (especially fibrin monomer/fibrinogen, an indicator of forming fibrin) in peritoneal fluid was slightly increased at 4 h, and abundantly present at 16 and 24 h, returning to control levels at 72 h. Fibrin degradation products were always present. From 2 h onward, adhesions were found. CONCLUSIONS: In contrast to the view that adhesions are formed as a result of a reduced fibrinolytic activity, our results demonstrate that tPA activity remained unchanged or slightly increased after surgical trauma, and point to increased fibrin formation rather than diminished fibrinolytic activity as the main cause of fibrin deposition after peritoneal trauma. Therapies directed at prevention of adhesion formation should therefore aim at avoiding massive fibrin production and at promoting fibrinolytic activity during the early period after trauma.     

Reference values of hemostasis related factors of healthy Japanese adults. I: Circadian fluctuation

The circadian fluctuation of hemostasis related parameters was examined on 16 healthy Japanese adults (male 9, female 7). Twenty one parameters were measured in this study, i.e. fibrinogen, the activity of F.II, F.V., F.VII, F.VIII, F.IX, F.X., F.XI, F.XII, antithrombin III, plasminogen, alpha 2-antiplasmin, as well as the antigen level of F.IX, von Willebrand Factor, protein C, tissue-type plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), beta-thromboglobulin, platelet factor 4, fibrinopeptide A, plasmin-alpha 2-antiplasmin complex and FDP. Fluctuation was not significant in almost all of the parameters except F.VIII, F.IX, beta-thromboglobulin, platelet factor 4, tPA and PAI-1. Although the fluctuations of F.VIII, F.IX, beta-thromboglobulin and platelet factor 4 were statistically significant, they remained within the normal ranges. On the other hand, tPA and free PAI-1 showed significant circadian fluctuation, of which levels were highest at 9:00. It was postulated that the significant circadian fluctuation of fibrinolytic activity will be regulated by the balance between tPA and PAI-1 in plasma.     

TM5275 prolongs secreted tissue plasminogen activator retention and enhances fibrinolysis on vascular endothelial cells

Introduction

Elevated plasminogen activator inhibitor-1 (PAI-1) reduces fibrinolytic potential in plasma, contributing to thrombotic disease. Thus, inhibiting PAI-1 activity is clinically desirable. We recently demonstrated that tissue plasminogen activator (tPA) remains on the surface of vascular endothelial cells (VECs) after secretion in a heavy-chain dependent manner, which is essential for high fibrinolytic activity on the surface of VECs, and that PAI-1 dissociates retained tPA from the cell surface as a result of high-molecular weight complex formation. Based on the model whereby amounts of tPA and its equilibrium with PAI-1 dynamically change after exocytosis, we examined how TM5275, a newly synthesized small molecule PAI-1 inhibitor, modulated tPA retention and VEC surface-derived fibrinolytic activity using microscopic techniques.

Materials and methods

The effects of TM5275 on the kinetics of the secretion and retention of green fluorescent protein (GFP)-tagged tPA (tPA-GFP) on VECs were analyzed using total internal reflection fluorescence microscopy. The effects of TM5275 on the generation of plasmin activity were evaluated by both plasminogen accumulation and fibrin clot lysis on tPA-GFP-expressing VECs using confocal laser scanning microscopy.

Results

TM5275 at concentrations of 20 and 100 μM significantly prolonged the retention of tPA-GFP on VECs by inhibiting tPA-GFP-PAI-1 high-molecular-weight complex formation. TM5275 enhanced the time-dependent accumulation of plasminogen as well as the dissolution of fibrin clots on and around the tPA-GFP-expressing cells.

Conclusions

The profibrinolytic effects of TM5275 were clearly demonstrated by the prolongation of tPA retention and enhancement of plasmin generation on the VEC surface as a result of PAI-1 inhibition.     

Association of the fibrinolytic system and hemorheology with symptoms in patients with carotid occlusive disease

BACKGROUND AND OBJECTIVES: The risk of stroke caused by a symptomatic high-grade carotid stenosis (CS) is high. Disturbed balance between the procoagulant and fibrinolytic activity in blood associated with unfavorable hemorheology could render CS symptomatic. We wanted to assess whether hemostatic and fibrinolytic plasma markers as well as basic indicators of hemorheology differentiate asymptomatic and symptomatic patients with a high-grade CS and whether they are associated with the macroscopic appearance of the plaque and the rate of microembolization. METHODS: We recruited 92 consecutive consenting patients referred to the neurological or the surgical department of our university teaching hospital for treatment of their high-grade CS. Blood samples were collected before surgery for determination of prothrombin fragments F1 and 2, thrombin-antithrombin complex, tissue-type plasminogen activator (tPA) activity and antigen, plasminogen activator inhibitor-1 (PAI-1) activity and antigen, D-dimer, homocysteine, fibrinogen, in plasma, and hematocrit in blood, and the patients underwent transcranial Doppler ultrasonology for evaluation of microembolic signals (MES). RESULTS: Patients with symptomatic plaques had higher hematocrit levels (p = 0.04), as well as trends for higher tPA antigen and MES rate (p = 0.07). Hematocrit, tPA antigen, and PAI-1 antigen and activity were positively correlated with the degree of stenosis. Ulceration was more common in symptomatic plaques but did not reflect variables of hemostasis or fibrinolysis. In multivariate analysis, tPA antigen and hematocrit were risk factors for a symptomatic high-grade stenosis. CONCLUSION: Mediators of fibrinolysis and unfavorable hemorheology may contribute to the development of a symptomatic disease in patients with a high-grade CS.     

Plasma PAI-1 levels in obese children--effect of weight loss and influence of PAI-1 promoter 4G/5G genotype

An association between an increase in plasminogen activator inhibitor type 1 (PAI-1) and obesity, and also between elevated levels of PAI-1 and the presence of PAI-1 promoter 4G allele has been described in adults and can contribute to increased risk of cardiovascular disease. It has also been suggested that in adults a decrease in adiposity has beneficial effects on the haemostatic system. However, less information is available regarding adiposity and fibrinolysis in children. The aim of the present study is to evaluate the effect of weight loss and the influence of the PAI-1 promoter 4G/5G genotype on the fibrinolytic system and lipid parameters in obese children. The clinical groups included 102 obese children and 105 controls of similar age and sex distribution. A significant decrease in fibrinolytic activity due to a significant increase in PAI-1 antigen and activity levels was observed in the obese children in comparison with the control group. In obese children, no significant differences in PAI-1 levels between the PAI-1 4G/5G genotypes were obtained. A significant correlation was observed between PAI-1 antigenic and functional levels and body mass index (BMI), as well as between PAI-1 levels and both triglyceride and insulin levels. No correlation between PAI-1 levels and either cholesterol or glucose levels was observed. After a three-month period of treatment to reduce weight, an increase in fibrinolytic activity due to a decrease in PAI- levels was observed in the obese children who had reduced their BMI in comparison with the group of obese children who did not show a decrease in their BMI. No significant differences between the two groups with respect to the variations in tissue type plasminogen activator and fibrinogen levels were obtained after three months of intervention to reduce weight. A significant correlation was observed between variations in BMI and variations in PAI-1 levels, and a significant inverse correlation was also observed between previous PAI-1 levels and variation in PAI-1 levels. Therefore, the largest decrease in PAI-1 levels was observed in the obese children with the highest previous PAI-1 levels. In conclusion, a decrease in BMI in obese children shows a favourable effect on the fibrinolytic system due to a decrease in PAI-1 levels. However, no influence of 4G/5G genotype on PAI-1 levels was observed.     

Fibrinolytic status in acute coronary syndromes: evidence of differences in relation to clinical features and pathophysiological pathways

Limited data are available on the role of innate fibrinolysis in acute coronary syndromes (ACS). In the present study we evaluated the dynamic alterations of fibrinolytic markers in patients presenting with ACS. Tissue-type-(tPA) and urokinase type-(uPA) plasminogen activators, plasminogen activator inhibitor (PAI-1) antigen and activity and thrombin activatable fibrinolysis inhibitor (TAFI) were analysed in 50 patients with ST elevation myocardial infarction (STEMI), 47 non-STEMI patients (NSTEMI), 40 patients with stable coronary artery disease (CAD) and 39 controls. The parameters were measured on day 1 and days 3, 7 and 30. Counts of monocyte subsets, monocyte-platelet aggregates and plasma inflammatory cytokines were assessed on admission. On day 1, TAFI was higher in NSTEMI vs. STEMI (p<0.001) while PAI-1 activity was higher in STEMI (p<0.001). In STEMI, uPA activity levels was low on day 1 but significantly increased on day 30 (p<0.001). TAFI levels were increased in NSTEMI on day 1 and gradually reduced by day 30 (p<0.05). In STEMI, TAFI levels peaked at day 7 (p<0.05) and dropped significantly by day 30 (p<0.05). CD14++CD16+ monocytes were independently associated with PAI-1 activity in ACS (p=0.03). Monocyte-platelet aggregates rather than platelet-free monocytes were an independent determinant of tPA, PAI-1 antigen and TAFI on a multivariate analysis (p<0.05). There are significant differences in fibrinolytic activity between patients with STEMI and NSTEMI. These changes could reflect the role of these factors in post-MI myocardial healing. Monocyte-platelet interactions are independently associated with the regulation of the fibrinolytic status in ACS.     

Improved fibrinolysis after 1-year treatment with HMG CoA reductase inhibitors in patients with coronary heart disease

The study was aimed to investigate the effect of two different statins on the levels of haemostatic variables reflecting procoagulant and fibrinolytic activity in patients with coronary heart disease (CHD), with the hypothesis that statins might beneficially modify these levels. Fifty-eight patients were randomized to treatment with atorvastatin (n=28) or simvastatin (n=30) for 1 year. The starting dose in both groups was 20 mg/day. Fasting blood samples were collected before and after 12-month treatment for determinations of fibrinogen, prothrombin fragment 1+2 (F1+2), plasma D-dimer, soluble tissue factor, tissue plasminogen activator (tPA) antigen, tPA activity, plasminogen activator inhibitor type-1 activity (PAI-1 activity) and serum D-dimer as a global test of fibrinolytic activity. In the total population, improved fibrinolytic activity was observed after 1 year with increased levels of serum D-dimer (P=.001) and tPA activity (P=.024) and a reduction in tPA antigen (P=.048). No statistically significant changes were observed in any of the measured coagulation variables. Separately examined, an improved fibrinolytic profile was seen in the atorvastatin group with a significant increase in serum D-dimer (P=.005), a borderline increase in tPA activity (P=.083) and a borderline reduction in tPA antigen (P=.069). Within the simvastatin group, a reduction in prothrombin F1+2 was observed (P=.038). The differences in changes between the groups were statistically significant only for global fibrinolysis (serum D-dimer, P=.046). In conclusion, an improved fibrinolytic profile was observed after statin treatment, most pronounced with atorvastatin. The results indicate that the drugs promote a profibrinolytic profile, and may in part explain the benefit of statin treatment rendered in the prevention of CHD.     

Tissue plasminogen activator and plasminogen activator inhibitor in patients with acute ischemic stroke: relation to stroke etiology

Recent studies suggest that high plasma levels of tissue-type plasminogen activator (tPA) and its inhibitor (plasminogen activator inhibitor-1, PAI-1) are markers of an increased risk of atherothrombotic ischemic events such as stroke and myocardial infarction. In this prospective study, we measured tPA antigen, PAI-1 antigen and activity, as well as tPA/PAI-1 complex in patients with acute stroke. Stroke subtypes were classified according to the TOAST criteria. From 132 consecutively screened patients, 89 (100%) were enrolled in this study, including 42 patients (47%) with large artery atherosclerosis (LAA), 32 (36%) with small vessel occlusion (SVO), and 15 (17%) with cardioembolism (CE). Nineteen age-matched neurologic patients without manifestations of cerebrovascular disease served as control subjects (CS). Patients with acute stroke had significantly higher plasma levels of tPA antigen (p < 0.001), PAI-1 antigen (p < 0.05) and PAI activity (p < 0.05) than patients in the control group. t-PA antigen, PAI activity and tPA/PAI-1 complex levels were similar regardless of stroke etiology. Only PAI-1 antigen was lower in patients with cardioembolic stroke than in stroke patients with LAA (p < 0.05). Plasma tPA antigen, PAI-1 antigen, and PAI activity are significantly increased in patients with acute ischemic stroke. Except for PAI-1 antigen, this increase appears not to be related to the underlying stroke etiology.     

Promotor polymorphisms of plasminogen activator inhibitor-1 and other thrombophilic genotypes in cerebral venous thrombosis: a case-control study in adults

Plasminogen activator inhibitor 1 (PAI-1) is the main inhibitor of tissue-type and urokinase-type plasminogen activator. A 4G/5G polymorphism in the promoter region of the PAI-1 gene has been reported to enhance the plasma levels of PAI-1. In particular, the 4G allele (guanosine deletion) has been linked with increased plasma PAI-1 levels, which may lead to impaired activity of the fibrinolytic system, thus increasing the incidence of thrombotic events. The aim of this case-control study was to analyze whether variants of the PAI-1 promotor genotype 4G/4G, 4G/5G and 5G/5G, in particular the 4G/5G-variant, constitute an independent risk factor of cerebral venous thrombosis (CVT). A total of 136 consecutive patients with proven CVT were compared to 1,054 DNA specimens of healthy controls from a population-based cohort. PAI-1 promotor polymorphisms were evaluated using polymerase chain reaction. No significant association of CVT with PAI-1 4G/5G was found in either the additive (OR 1.04; 95?% CI 0.78–1.38) or in the dominant model (OR 1.24; 95?% CI 0.72–2.13). Also, the prevalence of the other genotypes (4G/4G and 5G/5G) in patients was not significantly different from controls. When considering the variants of the PAI-1 promoter genotype in combination with known genetical thrombophilias, no differences were found either. As was expected, the prothrombin (G20210A) genotype was confirmed as an independent risk factor for CVT. We conclude that the 4G allele of the PAI-1 polymorphism does not increase the risk of CVT in adults.     

4G/5G polymorphism of the plasminogen activator inhibitor-1 gene and insertion/deletion polymorphism of the tissue-type plasminogen activator gene in atherothrombotic stroke

BACKGROUND AND PURPOSE: Decreased fibrinolytic capacity due to increased plasminogen activator inhibitor-1 (PAI-1) activity and decreased tissue-type plasminogen activator (t-PA) activity has been associated with hypertension or atherothrombotic disorders. The aims of this study were to observe associations of the genetic polymorphism for PAI-1 and t-PA with hypertension and atherothrombotic stroke, and to elucidate whether impaired fibrinolytic activity in atherothrombotic stroke was related to atherothrombosis per se or to other risk factors such as hypertension. METHODS: Patients with atherothrombotic stroke (n = 60), hypertension (n = 100), and control subjects (n = 100) were enrolled. We genotyped all subjects for 4G/5G polymorphism in the promoter region of the PAI-1 gene and the Alu-repeat insertion/deletion (I/D) polymorphism in intron h of the t-PA gene by polymerase chain reaction and endonuclease digestion. RESULTS: The frequency of the 4G/4G genotype of PAI-1 was significantly higher in the atherothrombotic stroke patients than the control subjects (41.7 versus 21%; p = 0.005), but not in the hypertensive subjects. There was a significant association between 4G/4G genotype of PAI-1 and atherothrombotic stroke (adjusted odds ratio = 3.11, 95% confidence interval 1.18-8.15), adjusting for age, sex, total cholesterol, low-density lipoprotein, triglyceride, and body mass index. However, the number of the I/I genotype of t-PA in the atherothrombotic stroke or hypertensive patients was virtually identical to the control subjects. CONCLUSION: Our results suggest that the 4G/4G genotype of the PAI-1 gene is significantly associated with an increased risk of atherothrombotic stroke. This finding also supports that impaired fibrinolytic activity in atherothrombotic stroke is related to atherothrombosis per se, but not to hypertension, one of the most important risk factors of atherothrombotic stroke.     

Plasminogen activator inhibitor-1 levels in severe and morbid obesity. Effect of weight loss and influence of 4G/5G polymorphism

INTRODUCTION: An association between an increase in plasminogen activator inhibitor type 1 and obesity has been described. It has also been shown that a decrease in adiposity has beneficial effects. However, less information is available regarding morbid obesity and hypofibrinolysis. The aim of the present study was to evaluate the effect of weight loss and the influence of the plasminogen activator inhibitor type 1 promoter 4G/5G genotype on plasminogen activator inhibitor type 1 levels in severe and morbid obesity. MATERIALS AND METHODS: Sixty-seven obese patients were studied before and three months after a weight reduction program, and compared with 67 controls. We determined plasminogen activator inhibitor type 1 antigen and activity levels, tissue type plasminogen activator antigen levels, 4G/5G genotype and biochemical parameters in both groups. RESULTS: A significant increase in plasminogen activator inhibitor type 1 antigen and activity was observed in obese patients in comparison with the control group (P<0.001). No significant differences in plasminogen activator inhibitor type 1 levels among 4G/5G genotypes were obtained. After weight loss, a significant decrease in plasminogen activator inhibitor type 1 antigen and activity was observed (P<0.001). A significant and positive correlation was observed in percentage changes in plasminogen activator inhibitor type 1 and body mass index (P=0.02). CONCLUSIONS: A decrease in body mass index in severe and morbid obesity shows a favourable effect on the fibrinolytic system due to a decrease in plasminogen activator inhibitor type 1 levels. However, no influence of 4G/5G polymorphism has been observed in this setting.     

Mild hyperhomocysteinemia is associated with a decreased fibrinolytic activity in patients after ST-elevation myocardial infarction

BACKGROUND: Elevated homocysteine (Hcy) levels have been associated with increased risk for cardiovascular disease and it has been shown that hyperhomocysteinemia is associated with increased levels of t-PA antigen in individuals without evidence for coronary artery disease (CAD). The aim of this study was to examine if Hcy plasma levels are associated with plasma levels of fibrinolytic factors in patients with CAD and a history of acute myocardial infarction. METHODS: We measured in 56 patients with CAD, 1 month after their first ST-elevation myocardial infarction, plasma levels of Hcy, the fibrinolytic parameters tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-type-1 (PAI-1), and t-PA-PAI-1 complexes. RESULTS: Hcy plasma levels inversely correlated with t-PA activity (r=-0.303, p<0.05). Patients with mild hyperhomocysteinemia (Hcy>15 micromol/L, n=8) showed significantly lower plasma levels of t-PA activity (p<0.05). Regression analysis revealed that out of cardiovascular risk factors and medical treatment only Hcy was significantly associated with t-PA activity. CONCLUSIONS: Patients with CAD after a first myocardial infarction and hyperhomocysteinemia show a reduced t-PA activity independently from cardiovascular risk factors and medical treatment. Homocysteine lowering therapies may increase fibrinolytic activity and thereby may help to avoid atherothrombotic events in patients with CAD after a first myocardial infarction.     

PAI and TPA gene polymorphisms in multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated chronic inflammatory demyelinating disease of the central nervous system. It manifests as acute focal inflammatory demyelination and axonal loss with limited remyelination and results in the chronic multifocal sclerotic plaques. Previously published data showed impaired fibrinolysis in MS. Tissue plasminogen activator t-PA is a serine protease that catalyses the activation of plasmin, which mediates the effects of fibrinolytic system. Alu insertion/deletion (I/D) genetic polymorphism in TPA gene in MS patients has not been analysed previously. The major inhibitor of t-PA is plasminogen activator inhibitor-1 (PAI-1). Its gene expression is modulated by functional genetic polymorphism in the promoter (4G/5G). In the present study, an association of two genetic polymorphisms with MS, its progression and subtype were analysed. TPA DD/PAI-1 4G4G genotype combination has reached a borderline significance for reduced risk for MS (OR = 0.543, 95% CI 0.301-0.978, P = 0.04), suggesting a gene-gene interaction. The explanation for this interaction may be a complex interplay between these two pleiotropic proteins within the brain tissue and in plasma.     

Fibrinolysis in normal subjects--comparison between plasminogen activator inhibitor and other components of the fibrinolytic system

We analyzed fibrinolytic parameters in 20 healthy men and 20 healthy women, aged from 25 to 59, before and after 10 and 20 min venous occlusion. The 10 min post-occlusion fibrinolytic activity measured directly in diluted unfractionated plasma by a highly sensitive 125I-fibrin plate assay correlated well with the activity of euglobulins determined by the classical fibrin plate assay (r = 0.729), but pre-stasis activities determined with these two methods did not correlate (r = 0.084). The enhancement of fibrinolytic activity after venous occlusion was mainly due to an increase of t-PA in the occluded vessels (4-fold increase t-PA antigen after 10 min and 8-fold after 20 min venous occlusion). Plasminogen activator inhibitor (PAI) activity and plasminogen activator inhibitor 1 (PAI-1)1 antigen levels at rest showed considerable dispersion ranging from 1.9 to 12.4 U/ml, respectively 6.9 to 77 ng/ml. A significant increase of PAI-1 antigen levels was observed after 10 and 20 min venous occlusion. At rest no correlation was found between PAI activity or PAI-1 antigen levels and the fibrinolytic activity measured by 125I-FPA. However, a high level of PAI-1 at rest was associated with a high prestasis antigen level of t-PA and a low fibrinolytic response after 10 min of venous stasis. Since the fibrinolytic response inversely correlated with PAI activity at rest, we conclude that its degree depends mainly on the presence of free PAI.     

Impaired fibrinolysis and postoperative thromboembolism in orthopedic patients.

The incidence of deep vein thrombosis (DVT) and pulmonary embolism was studied prospectively in patients undergoing elective total hip replacement. 96 patients were randomly allocated to receive either low molecular weight heparin (LMWH) or unfractionated heparin (UFH). All patients had bilateral phlebography and pulmonary perfusion/ventilation scintigraphy 10-12 days after surgery. The following fibrinolytic variables were analysed in plasma and related to thromboembolism: tissue plasminogen activator (t-PA) activity, t-PA antigen (t-PA Ag), plasminogen activator inhibitor (PAI-1) activity and PAI-1 antigen (PAI-1 Ag). No significant difference was found, regarding the fibrinolytic response to surgery, between patients treated with LMWH and UFH. The level of PAI-1 activity was significantly increased before operation in patients developing DVT as compared to non-DVT patients (p less than 0.03). Immediately after surgery and in the morning the first postoperative day the levels of PAI-1 activity, PAI-1 Ag and t-PA Ag were positively correlated to thromboembolism. PAI-1 activity was the only preoperative fibrinolytic variable correlated to thromboembolism.     

Plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism, coronary thrombosis, and myocardial infarction in middle-aged Finnish men who died suddenly

High plasminogen activator inhibitor-1 (PAI-1) plasma levels increase future risk of myocardial infarction (MI). The 4G allele of the 4G/5G polymorphism of the PAI-1 gene has been associated with increased plasma levels of PAI-1. The association of the PAI-1 polymorphism with coronary narrowings, coronary thrombosis and myocardial infarction (MI) was studied in a prospective autopsy series of 300 middle-aged Caucasian Finnish men (33 to 69 yrs) suffering sudden out-of-hospital death (Helsinki Sudden Death Study). The 4G allele was found in 76.8% of men with sudden cardiac death (SCD) compared to 67.5% in men who died accidentally and 63.2% in men who died of other diseases (p = 0.08 and p = 0.055, respectively). Men possessing the 4G allele had more often acute MI (OR 3.5; p <0.05) and coronary thrombosis (OR 5.5. p = 0.01) compared to 5G homozygotes. 5G homozygotes, comprising one third of the men in our study, seem to be at a decreased risk of thrombosis, whereas carriers of the common 4G allele have an increased risk of thrombosis, AMI and possibly SCD compared to 5G homozygotes.