Elevated fibrinogen and plasminogen activator inhibitor (PAI-1) in hypertension are related to metabolic risk factors for cardiovascular disease

Effects of hormone replacement therapy on blood coagulation and fibrinolysis in hypertensive and normotensive postmenopausal women

INTRODUCTION

Hypertension and estrogens are both prothrombotic. We investigated the effect of 12-month hormone replacement therapy (HRT) on hemostatic factors in mild to moderate essential hypertensive and normotensive postmenopausal women.

MATERIALS AND METHODS

A group of 38 hypertensive and 32 normotensive postmenopausal women received HRT (conjugated equine estrogen 0.625 mg plus medroxyprogesterone acetate 2.5 mg daily) for 12 months, and 19 hypertensive and 15 normotensive postmenopausal women did not. All hypertensive women had been administered antihypetensive drugs before the start of the study. Hemostatic factors, i.e., fibrogen, antithrombin, protein C activity, plasminogen activator inhibitor-1, D-dimer, and plasminogen, were measured in plasma of all women before, and 6 and 12 months after the start of study.

RESULT

The antithrombin levels of the hypertensive and normotensive women who received HRT had decreased at 6 (both P<0.001) and 12 months (P<0.001 and P<0.01) and their D-dimer at 12 months (both P<0.05) and plasminogen levels at 6 (both P<0.001) and 12 months (both P<0.001) has increased, but other hemostatic factors were unchanged. There were no changes in hemostatic factors in either control group.

CONCLUSION

HRT for 12 months activated blood coagulation and fibrinolysis in both hypertensive and normotensive postmenopausal women. Administration of CEE plus MPA therapy to hypertensive or normotensive postmenopausal women may be related to the thromboembolic events.

Is the effect of antihypertensive drugs on platelet aggregability and fibrinolysis clinically relevant?

Hypertension is associated with decreased fibrinolytic potential, mainly expressed as elevated plasma plasminogen activator inhibitor type 1 (PAI-1) levels, and increased platelet aggregability, which may account in part for the increased risk of atherosclerosis and its clinical complications in hypertensive patients. The effects of antihypertensive drugs on this prothrombotic state have been investigated and controversial findings have been reported, possibly because of differences in study designs, patients selected, and methodology used. Scarce and conflicting data exist about the effects of diuretics and beta-adrenoceptor antagonists on the fibrinolytic system, whereas ACE inhibitors have generally been reported to improve the fibrinolytic balance by decreasing plasma PAI-1 levels, calcium channel antagonists have been shown to increase tissue plasminogen activator (tPA) activity, and angiotensin II type 1 (AT(1)) receptor antagonists seem to exert neutral effects. beta-Adrenoceptor antagonists, calcium channel antagonists, and AT(1)-receptor antagonists have been reported to exert anti-aggregatory effects on platelets, while contrasting data exist about the influence of ACE inhibitors. Clinical implications of the changes induced by antihypertensive drugs on the fibrinolytic balance and platelet function are still debated. In particular, the question of whether these changes may translate into different degrees of cardiovascular protection in hypertensive patients remains unanswered. While awaiting more information from clinical trials, the choice of antihypertensive drugs, particularly in high-risk patients, should take into account effects beyond their BP-lowering efficacy. Selected agents should have a favorable, or at least neutral, impact on fibrinolytic function and platelet activity.

The complex between tPA and PAI-1: risk factor for myocardial infarction as studied in the SHEEP project

INTRODUCTION

The tPA/PAI-1 complex seems to be an important biochemical marker for myocardial reinfarction. Therefore we explored the distribution, correlation and interaction of plasma concentrations of tPA/PAI-1 complex in all available patients and matched controls in the Stockholm Heart Epidemiology Program (SHEEP).

METHODS AND PATIENTS

The SHEEP study is a case control study of 2246 patients with a first myocardial infarction (MI), of which 1267 surviving patients were subjected to blood sampling about 3 months after MI and compared with a control group, matched for age, sex and living area within the Stockholm County. The study consists of 886 (591 men and 295 women) patients and 1198 (753 men and 445 women) matched controls, who were all analysed for plasma tPA/PAI-1 complex.

RESULTS

The plasma concentration of tPA/PAI-1 complex was significantly associated with the risk for MI, for both genders. Synergistic interactions were observed in men for the co exposure to high plasma tPA/PAI-1 complex concentrations in combination with smoking (OR=4.6) or diabetes mellitus (OR=7.9). Synergism was also seen in combination with exposure to serum hypercholesterolemia or increased levels of apolipoprotein B. An antagonistic effect of the co exposure to high tPA/PAI-1 complex and hypertension was found among men with a similar tendency among women, but an antagonistic effect of increased waist/hip ratio was only observed among the women.

CONCLUSIONS

Measuring the plasma concentration of tPA/PAI-1 complex might be of practical value in assessing risk of MI for both genders, especially in those who are smokers or in patients with manifest diabetes mellitus.

Body fat is the main predictor of fibrinogen levels in healthy non-obese men

Previous studies have demonstrated that circulating levels of C-reactive protein (CRP), a marker of cardiovascular risk, are strictly related to body fatness. Elevated fibrinogen levels are also predictive of future cardiovascular events. The metabolic background of this relationship and the predictors of fibrinogen levels have not been well established. We aimed to evaluate whether fibrinogen levels are associated with body fat content and distribution and to determine the independent predictors of fibrinogen levels in a sample of healthy, non-obese, nonsmoking young adult men. Age, anthropometric measures (body mass index [BMI], waist-to-hip ratio [WHR]), total and regional fat content (determined by dual x-ray absorptiometry [DXA]), metabolic variables (total cholesterol [T-Chol], low-density lipoprotein cholesterol [LDL-C], and high-density lipoprotein cholesterol [HDL-C]; triglycerides [TG]; glucose and insulin levels; fasting insulin resistance index [FIRI]; blood pressure), interleukin-6 (IL-6), and acute-phase reactants levels (fibrinogen, highly sensitive [hs]-CRP) were determined in 87 healthy nonsmoking, non-obese subjects. Linear regression analysis was used to evaluate the association between body fat, fibrinogen, and metabolic variables, and multiple regression model analysis was used to examine the independent predictors of fibrinogen levels. Eighty-seven (30.5 +/- 3.5 years) non-obese (mean BMI 24.1 +/- 3.5) men were studied. Fibrinogen levels were strongly associated with measures of body fat and with metabolic variables. Total body fat (P < .0001) and LDL-cholesterol (P < .01) were the independent predictors of fibrinogen levels, accounting for 29.5% and 10.9% of its variance, respectively. Total body fat was the best independent predictor of hs-CRP levels, accounting for 32.5 % of its variance. We conclude that in healthy, non-obese subjects, body fat content is the main predictor of fibrinogen levels, as well of hs-CRP levels. These findings support the speculation that there is a direct mechanism by which adipose tissue might regulate the levels of circulating acute-phase reactants.

The plasma levels of plasminogen activator inhibitor-1 in subjects with white coat hypertension

High plasminogen activator inhibitor-1 (PAI-1) levels are potential risk factors for cardiovascular disease. The risk profile of white coat hypertension (WCHT) has not yet been completely clear. In this study, we aimed to determine the plasma levels of PAI-1, markers of fibrinolysis and increased cardiovascular disease risk, in a group with WCHT and to obtain clinical results by comparing WCHT group with hypertensive and healthy groups. Age and sex matched 30 patients with WCHT, 30 patients with sustained hypertension, and 30 healthy subjects were included in the study. The plasma levels of PAI-1 were significantly higher in sustained hypertension group than in WCHT group (p < 0.01). There were significantly higher levels in patients with WCHT than in control group (p < 0.01). Our data suggests one possible mechanism by which WCHT subjects may be at increased cardiovascular risk.

Metabolic syndrome: an appraisal of the pro-inflammatory and procoagulant status

Inflammation and hypercoagulability predispose to atherothrombosis and seem to be important features of the metabolic syndrome. The most convincing evidence is the association with increased levels of C-reactive protein. The hemostatic abnormality that has been most consistently associated with insulin resistance is an elevated plasminogen activator inhibitor-1 level. In contrast, markers of hypercoagulability have been associated inconsistently with hyperinsulinemia and glucose intolerance. Fibrinogen clusters with inflammatory factors, which suggests involvement of adipose tissue-generated inflammatory cytokines. Elevated von Willebrand's factor and factor VIII levels aggregate with indicators of endothelial injury,whereas vitamin K-dependent coagulation proteins correlate with triglyceride levels.

The metabolic syndrome and C-reactive protein, fibrinogen, and leukocyte count: findings from the Third National Health and Nutrition Examination Survey

To examine the association between the metabolic syndrome and C-reactive protein, fibrinogen, and leukocyte count, the author did a cross-sectional analysis of data from 8570 participants aged >/=20 years from the Third National Health and Nutrition Examination Survey (1988-1994). The metabolic syndrome was defined using criteria established by the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. The age-adjusted prevalence of having an elevated C-reactive protein concentration was 29.0% (S.E.: 1.6%) for participants with the metabolic syndrome and 12.1% (S.E.: 0.6%) for participants without the metabolic syndrome (adjusted odds ratio (OR), 2.80; 95% confidence interval (CI): 2.36, 3.33). Compared with participants who had no abnormalities, the corresponding adjusted ORs were 1.91 (95% CI: 1.27, 2.87), 3.00 (95% CI: 1.96, 4.60), 5.01 (95% CI: 3.39, 7.41), 5.97 (95% CI: 3.83, 9.31), and 6.79 (95% CI: 3.55, 12.99) for participants with 1, 2, 3, 4, and 5 metabolic abnormalities, respectively. Participants with the metabolic syndrome had higher fibrinogen concentrations and white blood cell counts than those without this syndrome. Many people with the metabolic syndrome have a low-grade inflammation, which may increase their risk for future adverse events. A better understanding of the potential consequences of the high prevalence of low-grade inflammation among people with the metabolic syndrome is needed.

New atherosclerosis risk factors in obese, hypertensive and diabetic children and adolescents

In the last few years it has been proved that risk factors for atherosclerosis are present in children and adolescents, and that already at this early age they are connected with anatomic, atheromatous changes in vessels. These changes can not be fully explained as occurring in young people exhibiting traditional risk factors for the disease. The aim of the study was to evaluate levels of several new atherosclerosis risk factors (lipoprotein (a) (Lp(a)), apolipoprotein A-I (Apo A-I), apolipoprotein B (Apo B), homocysteine (Hcy), fibrinogen (FB), tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor type 1 (PAI-1)) in children and adolescents with traditional risk factors (obesity, hypertension, diabetes).

MATERIALS AND METHODS

The study group consisted of 285 children and adolescents aged 14.3 years. Children were divided according to their main disease into groups: group A, children with obesity (n=49); group B, children with obesity and coexisting hypertension (n=56); group C, children with hypertension (n=58) and group D, children with diabetes (n=122). Control group consisted of 79 healthy children and adolescents aged 14.1 years. Lp(a), Apo A-I and Apo B levels were estimated by use of immunoturbidimetric methods; total Hcy, FB, t-PA and PAI-1 were estimated by use of immunoenzymatic methods.

RESULTS

Lp(a) level in the total study group was 30 mg/dl and was over twice higher than in control group, 14 mg/dl. Apo A-I level was significantly lower in group A (127.6 mg/dl) and in group B (125.8 mg/dl) versus 135.6 mg/dl in controls. The level of Apo B was significantly higher in total study group (86.2 mg/dl) and in groups A, B and D versus 73.5 mg/dl in controls. Hcy was higher in group B (8 micromol/l) and in group C (9.4 micromol/l) versus 6.2 micromol/l in the control group. The FB level was higher in the total study group (276.7 mg/dl) and in groups A (318.8 mg/dl) and B (322.6 mg/dl) versus 252.8 mg/dl in controls. Significantly higher t-PA level was found in groups A (9 ng/ml) and B (9.7 ng/ml) versus 7.3 ng/ml in controls, and PAI-1 level was significantly higher in the total study group (62.3 ng/ml) and in groups A (73.8 ng/ml), B (78 ng/ml) and C (73 ng/ml) versus 42.4 ng/ml in the control group. Correlation analysis showed significant relationship between body mass index (BMI) and Apo B, Hcy, FB, t-PA and PAI-1. Blood pressure values correlated positively with Hcy. Correlations were verified in multiple regression analysis models: FB and t-PA levels depended on BMI, and Hcy depended on systolic blood pressure.

CONCLUSIONS

(1) Young obese, hypertensive and diabetic patients present significant disturbances in lipid metabolism, regarding mainly total cholesterol, LDL, triglycerides, as well as Lp(a), Apo A-I and Apo B levels. Unfavourable lipid profile is characteristic mainly for children with obesity and accompanying hypertension. (2) Elevated Hcy levels are found in children with hypertension. (3) Elevated FB level and diminished fibrinolytic activity are characteristic of obese children.

Association between preheparin serum lipoprotein lipase mass and acute myocardial infarction in Japanese men

A sensitive immunoassay system using a specific monoclonal antibody against lipoprotein lipase (LPL) recently demonstrated the presence of an LPL mass in preheparin serum. We reported that a preheparin serum LPL mass (pre-LPL mass) reflected the level of functioning LPL activity in the whole body and could be deeply involved in the progression of coronary atherosclerosis of stable organic angina pectoris. We examined the relation between the pre-LPL mass and acute myocardial infarction (AMI). We studied 44 males with AMI (AMI group) and 16 males with a normal coronary artery (NCA group), and measured the pre-LPL mass by enzyme-linked immunosorbent assay. Coronary risk factors including the pre-LPL mass were compared between the two groups and multiple regression analysis was performed for AMI. There were no significant differences in the lipid data, but the pre-LPL mass level was significantly low in the AMI group (52 +/- 16 vs 41 +/- 14 ng/ml, p = 0.01), and a low pre-LPL mass concentration was observed in the small sized LDL group and/or the Midband positive group. Multiple regression analysis revealed that a low pre-LPL mass and hypertriglyceridemia were independent risk factors for AMI (t value = 2.1, 2.4). The result indicates that a low pre-LPL mass may be an important risk factor for AMI and stable organic angina pectoris.

Hypoxia-inducible factor-1 and hypoxia response elements mediate the induction of plasminogen activator inhibitor-1 gene expression by insulin in primary rat hepatocytes

The expression of the plasminogen activator inhibitor-1 (PAI-1) gene is enhanced by insulin both in vivo and in various cell types. Because insulin exerts a number of its biologic activities via the phosphatidylinositol 3-kinase and protein kinase B (PI3K/PKB) signaling pathway, it was the aim of the present study to investigate the role of the PI3K/PKB pathway in the expression of the PAI-1 gene and to identify the insulin responsive promoter sequences. It was shown that the induction of PAI-1 mRNA and protein expression by insulin and mild hypoxia could be repressed by the PI3K inhibitor wortmannin. Overexpression of a constitutively active PKB led to induction of PAI-1 mRNA expression and of luciferase (Luc) activity from a gene construct containing 766 bp of the rat PAI-1 promoter. Mutation of the hypoxia response elements (HRE-1 and HRE-2) in rat PAI-1 promoter, which could bind hypoxia inducible factor-1 (HIF-1), abolished the induction of PAI-1 by insulin and PKB. Insulin and the constitutive active PKB also induced Luc expression in cells transfected with the pGl3EPO-HRE Luc construct, containing 3 copies of the HRE from the erythropoietin gene in front of the SV40 promoter. Furthermore, insulin and the active PKB enhanced all 3 HIF alpha-subunit protein levels and HIF-1 DNA-binding activity, as shown by electrophoretic mobility shift assays (EMSAs). Thus, the insulin-dependent activation of the PAI-1 gene expression can be mediated via the PI3K/PKB pathway and the transcription factor HIF-1 binding to the HREs in the PAI-1 gene promoter.

Parental history of hypertension is associated with coagulation–fibrinolytic balance disorders

It has been previously shown that essential hypertension (EH) is associated with coagulation-fibrinolytic balance disorders. Our study was conducted in order to investigate disturbances in coagulation-fibrinolysis in offsprings of hypertensive parents. Two groups were studied: 44 healthy normotensive individuals (17 male, 27 female, age range 12-22 years) with a documented family history of hypertension and 33 individuals (14 male, 19 female, age range 11-21 years) without a family history of essential hypertension. The following parameters were determined in both groups: plasminogen activator inhibitor-1 antigen, tissue plasminogen activator antigen, fibrinogen, fibrin degradation products, thrombomodulin, protein S antigen, protein C activity, von Willebrand factor Ag, factor VII and factor XII activity. Additionally, systolic and diastolic blood pressure, insulin levels, blood lipids and heart rate were determined. The two groups were not found to have differences with respect to age, gender, body mass index, blood lipids and insulin levels. Hypertensive offsprings had significantly higher plasma levels of plasminogen activator inhibitor-1 antigen, fibrinogen, fibrin degradation products, protein S antigen and factor XII activity, while no differences were observed to the other haemostatic variables studied. Hence, offsprings of hypertensives had significantly higher diastolic blood pressure and heart rate. In conclusion, alterations regarding blood pressure, heart rate and fibrinolytic function exist in offsprings of hypertensive parents compared to individuals without family history of hypertension.

Tissue factor pathway inhibitor (TFPI) release after heparin stimulation is increased in Type 1 diabetic patients with albuminuria

AIMS

To study heparin-stimulated TFPI release in relation to complications in Type 1 diabetic patients.

SUBJECTS AND METHODS

Nineteen uncomplicated Type 1 diabetic patients (group I) were compared with 18 patients with retinopathy (group II), and nine patients with retinopathy and albuminuria (group III). Blood samples were taken before (basal) and till 30 min after 5000 IU of heparin i.v. (post-heparin). TFPI activity was measured chromogenically. Von Willebrand factor, tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) and thrombomodulin were also measured.

RESULTS

Basal TFPI activity was higher in group III (121 +/- 10%) compared with group II (111 +/- 8%) or group I (110 +/- 13%) (P < 0.05), and strongly correlated with albuminuria (r = 0.66, P < 0.05). At all time points after heparin administration, TFPI activity in group III was significantly higher than in group I. TFPI activity was also higher in group III than in group II 5-30 min post-heparin. The increase in post-heparin TFPI activity, measured as the incremental area under the curve, was higher in group III compared with group I (65 +/- 7 vs. 59 +/- 4; P < 0.05). Of the other parameters, only thrombomodulin was higher in group III (44 +/- 24 vs. 26 +/- 7 (group II) and 28 +/- 9 ng/ml (group I); P < 0.01).

CONCLUSIONS

We conclude that basal and post-heparin TFPI activity is increased in albuminuric patients. The increase in heparin-stimulated TFPI release in patients with albuminuria is higher than in patients with retinopathy or without complications. This could be the result of altered endothelial glycosaminoglycan characteristics.

Tissue factor pathway inhibitor and other endothelium-dependent hemostatic factors in elderly individuals with normal or impaired glucose tolerance and type 2 diabetes

OBJECTIVE

Impaired glucose tolerance (IGT) is believed to be a prediabetic phase that precedes the development of type 2 diabetes. In elderly subjects, IGT and diabetes are both independently associated with the occurrence of cardiovascular disease. Endothelial damage precedes atherosclerotic changes of the vascular wall. Therefore, several markers of endothelial dysfunction were examined in elderly subjects with IGT and elderly patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Von Willebrand factor (vWF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor type-1 (PAI-1), and thrombomodulin were studied as markers of endothelial dysfunction in a population-based study of elderly subjects with normal glucose tolerance (NGT) or IGT and type 2 diabetes. In addition to these endothelium-dependent factors, we also investigated tissue factor pathway inhibitor (TFPI) activity in relation to metabolic parameters and cardiovascular risk factors.

RESULTS

All data were adjusted for age. Increased levels of vWF antigen, t-PA antigen, and PAI-1 activity were seen in the IGT and diabetic group compared with the NGT group. TFPI activity and thrombomodulin levels were increased in all elderly subjects, and no differences were seen between the groups. There was a positive association between HbA(1c) and TFPI activity and vWF antigen. Fasting blood glucose levels correlated with vWF antigen, t-PA antigen, and PAI-1 activity, whereas urine albumin excretion correlated with TFPI activity, vWF antigen, and PAI-1 activity. Serum insulin levels correlated strongly not only with vWF antigen and t-PA antigen but also with PAI-1 activity. This correlation did not change after further adjustment for serum glucose and HbA(1c), which may suggest that in the elderly subjects, impaired fibrinolysis is probably associated with insulin resistance. There were no associations between the endothelium-dependent hemostatic factors and lipids, except for a negative correlation between HDL cholesterol and thrombomodulin.

CONCLUSIONS

In elderly subjects with IGT, several endothelium-dependent hemostatic factors are already consistently increased, indicating endothelial damage in this stage.

Increased leptin concentrations correlate with increased concentrations of inflammatory markers in morbidly obese individuals

OBJECTIVE

To study whether an increase of plasma leptin concentrations, as observed in the case of increased body weight, is associated with an inflammatory state.

SUBJECTS

Sixty-three healthy subjects with body mass index (BMI) ranging from 20 to 61 kg/m2.

MEASUREMENTS

Plasma concentrations of leptin, the inflammatory parameter soluble TNF-alpha receptors (TNFR55 and TNFR75), the acute phase proteins lipopolysaccharide binding protein (LBP), serum amyloid A (SAA), alpha-acid glycoprotein (AGP), C-reactive protein (CRP), plasminogen activator inhibitor-1 (PAI-1) and the anti-inflammatory soluble Interleukin-1 decoy receptor (sIL-1RII) were measured.

RESULTS

As expected, BMI correlated significantly with leptin (r=0.823, P<0.001), but also with all acute phase proteins, both soluble TNF receptors and PAI concentrations. After correction for BMI and sex, no significant correlation between leptin and the acute phase proteins was seen. Interestingly, however, leptin strongly correlated with both TNF receptors (r=0.523, P<0.001 for TNFR55 and r=0.438, P<0.001 for TNFR75).

CONCLUSIONS

This study shows the development of a pro-inflammatory state with increasing body weight. The BMI independent relationship between leptin and both soluble TNF-receptors is consistent with a regulatory role for leptin in the inflammatory state in morbidly obese subjects.

Plasminogen activator inhibitor type-1 in cardiovascular disease. Status report 2001

Plasminogen activator inhibitor type-1 (PAI-1) is known to contribute to thrombus formation and to the development and the clinical course of acute and chronic cardiovascular disease, as well as of other arterial and venous thromboembolic diseases. Recently, an important role of elevated pretreatment levels of PAI-1 for failure of thrombolytic therapy of acute myocardial infarction has been discussed. PAI-1 plasma levels depend on the one hand on gene regulation but are related on the other hand to known risk factors of atherosclerosis like insulin resistance, diabetes or hypertriglyceridemia, respectively. Furthermore, an activated renin-angiotensin-aldosterone system (RAAS) significantly contributes to the upregulation of PAI-1 concentration via a receptor-mediated mechanism. In accordance to the known mechanisms of regulation of PAI-1 plasma levels, the use of specific agents like antidiabetic drugs, fibrates, statins, ACE inhibitors and angiotensin II type-1 receptor-blockers may contribute to the downregulation of circulating PAI-1 and, therefore, increase the fibrinolytic capacity and consecutively counteract the thrombotic tendency. To further improve the efficacy of thrombolytic therapy, a PAI-1 resistant variant of t-PA, TNK-t-PA, has been developed and is now available for acute myocardial infarction.

Pathophysiology of oxidative stress in diabetes mellitus

Oxidative stress is believed to play an important role, albeit not fully recognized, in the development of vascular complications in diabetes mellitus (DM) particularly type 2. In the majority of studies, attention was focused on lipid oxidation, specifically on that of low-density lipoproteins (LDLs). More recent investigations have revealed that it is not only the lipid but also the apolipoprotein moiety of LDL that becomes oxidatively modified resulting in the formation of insoluble aggregates. Consequently, it has been documented that LDL aggregation was due to the hydroxyl radical-induced dityrosine crosslinking between apo B monomers. In DM patients with atherosclerotic complications, intravascular fibrous deposits were shown to contain, in addition to oxidized LDL, a fibrin-like material (FLM). This material is immunologically identical to fibrin that is normally formed as a result of intravascular activation of the blood coagulation cascade. Although DM patients with vascular disease display increased concentration of plasma fibrinogen (Fbg), the precursor of fibrin, no markers of full blown activation of blood coagulation could be found.

Plasminogen activator inhibitor type-1 (part one): basic mechanisms, regulation, and role for thromboembolic disease

Plasminogen activator inhibitor type-1 (PAI-1) is a rapid inhibitor of tissue plasminogen activator (tPA) in circulation. Evidence suggests that the PAI-1 concentration is responsible for the regulation of the endogenous fibrinolytic system through its tPA/PAI-1 interactions. Accordingly, increased levels of PAI-1 have emerged as a masker for an increased thrombolic risk. This article represents a status report of mechanism of action, regulation of plasma levels, as well as the role of PAI-1 in arterial and venous thromboembolic disease.

Diabetes and endothelial dysfunction: a clinical perspective

The main etiology for mortality and a great percent of morbidity in patients with diabetes mellitus is atherosclerosis. A hypothesis for the initial lesion of atherosclerosis is endothelial dysfunction, defined pragmatically as changes in the concentration of the chemical messengers produced by the endothelial cell and/or by blunting of the nitric oxide-dependent vasodilatory response to acetylcholine or hyperemia. Endothelial dysfunction has been documented in patients with diabetes and in individuals with insulin resistance or at high risk for developing type 2 diabetes. Factors associated with endothelial dysfunction in diabetes include activation of protein kinase C, overexpression of growth factors and/or cytokines, and oxidative stress. Several therapeutic interventions have been tested in clinical trials aimed at improving endothelial function in patients with diabetes. Insulin sensitizers may have a beneficial effect in the short term, but the virtual absence of trials with cardiovascular end-points preclude any definitive conclusion. Two trials offer optimism that treatment with ACE inhibitors may have a positive impact on the progression of atherosclerosis. Although widely used, the effect of hypolipidemic agents on endothelial function in diabetes is not clear. The role of antioxidant therapy is controversial. No data have been published regarding the effects of hormonal replacement therapy on endothelial dysfunction in postmenopausal women with type 2 diabetes.

Close relationship of tissue plasminogen activator-plasminogen activator inhibitor-1 complex with multiple organ dysfunction syndrome investigated by means of the artificial pancreas

BACKGROUND

Glucose tolerance (GT) has not been taken into consideration in investigations concerning relationships between coagulopathy and multiple organ dysfunction syndrome (MODS), and endothelial cell activation/endothelial cell injury (ECA/ECI) in septic patients, although coagulopathy is known to be influenced by blood glucose level. We investigated those relationships under strict blood glucose control and evaluation of GT with the glucose clamp method by means of the artificial pancreas in nine septic patients with glucose intolerance. The relationships between GT and blood stress related hormone levels (SRH) were also investigated.

METHODS

The amount of metabolized glucose (M value), as the parameter of GT, was measured by the euglycemic hyperinsulinemic glucose clamp method, in which the blood glucose level was clamped at 80 mg/dl under a continuous insulin infusion rate of 1.12 mU/kg per min, using the artificial pancreas, STG-22. Multiple organ failure (MOF) score was calculated using the MOF criteria of Japanese Association for Critical Care Medicine. Regarding coagulopathy, the following parameters were used: disseminated intravascular coagulation (DIC) score (calculated from the DIC criteria of the Ministry of Health and Welfare of Japan) and the parameters used for calculating DIC score, protein-C, protein-S, plasminogen, antithrombin III (AT-III), plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator-PAI-1 (tPA-PAI-1) complex. Thrombomodulin (TM) was measured as the indicator of ECI.

RESULTS

There were no significant correlations between M value and SRH, parameters indicating coagulopathy and the MOF score. The MOF score and blood TM levels were positively correlated with DIC score, thrombin-AT-III complex and tPA-PAI-1 complex, and negatively correlated with blood platelet count.

CONCLUSIONS

GT was not significantly related to SRH, coagulopathy and MODS under strict blood glucose control. Hypercoagulability was closely related to MODS and ECI. Among the parameters indicating coagulopathy, tPA-PAI-1 complex, which is considered to originate from ECA, seemed to be a sensitive parameter of MODS and ECI, and might be a predictive marker of MODS. The treatment for reducing hypercoagulability and ECA/ECI were thought to be justified as one of the therapies for acutely ill septic patients.

Clustering of procoagulation, inflammation, and fibrinolysis variables with metabolic factors in insulin resistance syndrome

The known metabolic cardiovascular disease risk factors associated with insulin resistance syndrome (IRS) do not adequately explain the excess cardiovascular disease risk attributed to this syndrome, and abnormalities in hemostatic variables may contribute to this excess risk. Using data from 322 nondiabetic elderly men and women (aged 65-100 years) participating in the Cardiovascular Health Study during 1989-1990, the authors performed factor analysis on 10 metabolic risk factors associated with IRS and 11 procoagulation, inflammation, and fibrinolysis variables to examine the clustering of the metabolic and hemostatic risk markers. Factor analysis of the metabolic variables confirmed four uncorrelated factors: body mass, insulin/glucose, lipids, and blood pressure. Adding the hemostatic variables yielded three new factors interpreted as inflammation, vitamin K-dependent proteins, and procoagulant activity. Plasminogen activator inhibitor-1 clustered with the body mass factor, supporting the hypothesis that obesity is related to impaired fibrinolysis. Fibrinogen clustered with the inflammation summary factor rather than procoagulant activity, supporting the position that fibrinogen principally reflects underlying inflammation rather than procoagulant potential. The authors conclude that should hemostatic variables be shown to contribute to IRS-related cardiovascular disease, apart from plasminogen activator inhibitor-1, they may do so independently of the established metabolic abnormalities.

Effect of the angiotensin-converting enzyme inhibitor perindopril on haemostasis in essential hypertension

Endothelial damage, platelet hyperactivity and other changes of blood coagulation may play a role in the vascular complications of essential hypertension. Undesirable changes of haemostasis induced by some anti-hypertensive drugs can encourage the acceleration of atherogenesis. Therefore, the effect of angiotensin-converting enzyme (ACE)-inhibitors on haemostasis is of interest. The therapeutic dose of perindopril was previously shown to reduce platelet aggregation. In the present study, selected parameters of haemostasis were investigated in 23 patients with first and second stage of non-treated essential hypertension. The measurements were carried out before therapy, after 1 week of placebo administration, and after 1 week and after 1 month of ACE-inhibitor perindopril therapy in a once-daily dose of 4 mg. Plasma prothrombin time, activated partial thromboplastin time, fibrinogen level, plasminogen and antithrombin III activities, protein C and free protein S antigens, total fibrinolytic activity as well as fibrin monomers and D-dimers were assayed. There were no significant changes in any haemostasis variables investigated following placebo administration or perindopril therapy. On the basis of this study, no unfavourable effects on haemostasis induced by this therapy were found. The platelet-inhibitory effect of perindopril, without any harmful effects on coagulation or fibrinolytic activity and coagulation inhibitors, is desirable in the new approach to hypertension treatment. These properties of perindopril may be important in terms of the beneficial role of anti-hypertensive drugs in cardiovascular morbidity.

Implications of cardiovascular risk in patients with type 2 diabetes who have abnormal lipid profiles: is lower enough?

Patients with type 2 diabetes are at high risk for coronary heart disease (CHD); frequently, these patients have abnormal lipid profiles, placing them at even greater risk. A syndrome of insulin resistance, hyperinsulinaemia, hypertension, and high levels of fibrinogen and plasminogen activator inhibitor contributes to cardiovascular risk, which is not sufficiently decreased by glycaemic control alone. In several large interventional trials, CHD risk in patients with diabetes was substantially reduced by aggressive lipid-lowering therapy. In patients with diabetes, CHD, low high-density lipoprotein levels, and normal low-density lipoprotein levels, gemfibrozil reduced fatal and non-fatal CHD events. For lipid-lowering in patients with diabetes and CHD, pravastatin and simvastatin are the only HMG-CoA reductase inhibitors shown to reduce fatal and non-fatal CHD events. Of these, pravastatin has less potential for drug-drug interactions and may be safer to use, particularly for combination therapy with fibric acid derivatives, as may now be important for CHD prevention in mixed dyslipidaemias.

Plasma levels of tissue plasminogen activator/plasminogen activator inhibitor-1 complex and von Willebrand factor are significant risk markers for recurrent myocardial infarction in the Stockholm Heart Epidemiology Program (SHEEP) study

An impaired fibrinolytic function due to elevated plasma levels of plasminogen activator inhibitor (PAI)-1 activity or tissue plasminogen activator (tPA) antigen is correlated with the development of myocardial infarction (MI) in patients with manifest coronary heart disease. Recently, methods for determining the specific tPA/inhibitor complexes constituting tPA antigen in plasma have become available. In the Stockholm Heart Epidemiology Program (SHEEP) study, 86 of 1212 MI patients, subjected to blood sampling in a metabolically stable period, suffered reinfarction before the end of 1996. These individuals have been compared with an approximately equal number of matched MI patients without recurrence and a group of matched healthy control subjects regarding the plasma concentrations of some hemostatic factors. The hemostatic compounds studied (fibrinogen, von Willebrand factor, tPA antigen, PAI-1, and the tPA/PAI-1 complex) were typically higher in the groups (men and women) with recurrence of MI compared with those without. The plasma concentrations were also typically higher in the pooled groups of patients compared with the groups of healthy control subjects. The largest between-group differences were found for the plasma tPA/PAI-1 complex. The crude odds ratio for reinfarction associated with higher concentration (>/=75th percentile among the control subjects) of tPA/PAI-1 was 1.8 (95% CI 1.1 to 3.1); the corresponding crude odds ratio for von Willebrand factor was 2.3 (1. 3 to 4.0). The tPA/PAI-1 complex correlated strongly with PAI-1 and tPA antigen in all groups and with serum triglycerides and body mass index in all groups except for women with reinfarction. An increased plasma level of tPA/PAI-1 complex is a novel risk marker for recurrent MI in men and women. Most likely, increased plasma levels of tPA/PAI-1 complex reflect impaired fibrinolysis, because the correlation with PAI-1 is strong. Further support is obtained indicating that the plasma concentration of von Willebrand factor is also an important risk marker for recurrent MI.

Relation of serum triglyceride levels to survival after coronary artery bypass grafting

We performed a prospective observational study on 6,602 subjects (94% for 5 years and 34% for 10 to 15 years) who underwent coronary artery bypass graft surgery (CABG) between 1982 and 1992. We examined whether triglyceride concentrations adjusted for other factors (total cholesterol, history of diabetes mellitus, systemic hypertension, left ventricular function, number of coronary arteries significantly narrowed, and use of the internal thoracic arteries) explained total and event-free survival. These analyses were duplicated within gender (1,354 women and 5,248 men). This approach allowed a determination of any gender-related disparities in lipid predictors. Triglycerides in the highest quartile were associated with an increased risk of mortality of 20% (confidence interval [CI] 1.0 to 1.4). Similar risk was seen for event-free survival. Although there was no evidence of gender differences in adjusted survival (p = 0.33), a gender by triglyceride interaction (p = 0.004) indicated that the response to high triglycerides as related to survival did differ by gender. Specifically, women had a dramatically higher risk (hazard ratio [HR] 1.5, CI 1.1 to 2.1) than men (HR 1.1, CI 0.9 to 1. 3). Both men and women did have triglyceride-associated risk with regard to event-free survival (HR in men 1.2, CI 1.1 to 1.4; HR in women 1.4, CI 1.1 to 1.8). Examination of high-density lipoprotein cholesterol in a subcohort did not eliminate the observed triglyceride effects. Thus, triglyceride baseline values are primary determinants (similar to baseline left ventricular function or extent of coronary disease) for long-term total and event-free mortality after CABG in women but not in men.

Relationship between lipoprotein(a) phenotypes and plaminogen activator inhibitor type 1 in diabetic patients

It has been demonstrated in vitro that lipoprotein(a) [Lp(a)] increases the endothelial synthesis of plasminogen activator inhibitor 1 (PAI-1). However, this effect in vivo is controversial, and the possible relationship between PAI-1 and Lp(a) phenotypes has not been evaluated. The aim of the study was to determine the influence of Lp(a) and its phenotypes on PAI-1 serum concentrations in diabetic patients. For this purpose we include 75 Caucasian diabetic patients (34 consecutive type I and 41 consecutive type II) without late diabetic complications. Lp(a) and PAI-1 were assessed by ELISA. Lp(a) phenotypes were determined by SDS-PAGE followed by immunoblotting, and grouped according to size in small (F,B,S1,S2), big (S3,S4), and null. A linear correlation between Lp(a) and PAI-1 was not observed either as a whole or when type I and type II diabetic patients were analyzed separately. However, significant differences were detected in PAI-1 levels when Lp(a) phenotypes were considered (small: 42.1+/-31.8 ng/mL; big: 37.2+/-26.1 ng/mL; null: 14.4+/-14.4; p< 0.05). The significant differences were due to the low PAI-1 concentrations observed in patients with null phenotype. Our results suggest that fibrinolytic activity might be preserved in diabetic patients with null Lp(a) phenotype. Furthermore, it could be speculated that diabetic patients with null phenotype should be considered at low risk to develop cardiovascular disease.

Does hypertension confer a hypercoagulable state in stroke-prone spontaneously hypertensive rats?

OBJECTIVE

To verify whether hypertension confers a hypercoagulable state in a hypertensive animal model.

DESIGN

The parameters of blood coagulation were compared between stroke-prone spontaneously hypertensive rats (SHR-SP) and Wistar-Kyoto (WKY) rats. Each rat group consisted of a younger subgroup at 8-12 weeks old (n = 12) and an older subgroup at 16-20 weeks old (n = 12).

METHODS

Prothrombin time (PT), activated partial thromboplastin time (APTT), fluorogenic PT, fibrinogen, fibrin/fibrinogen degradation products (FDP), thrombin-anti-thrombin III complex (TAT), factor Xa activity, anti-thrombin III (AT-III), tissue factor pathway inhibitor (TFPI), protein C and C1 inhibitor were measured in both rat groups.

RESULTS

There was no significant difference in FDP and TAT levels between SHR-SP and WKY rats even at 16-20 weeks when SHR-SP developed severe hypertensive vascular lesions. Contrary to expectations, fluorogenic PT and factor Xa activity were significantly lower in SHR-SP than in WKY rats. While there was no significant difference in AT-III, TFPI and protein C activities between SHR-SP and WKY rats, C1 inhibitor activity was significantly higher in SHR-SP than in WKY rats. The elevated C1 inhibitor activity was inversely correlated with the reduced factor Xa activity. Gel-filtered fractionated plasma with C1 inhibitor activity had an inhibitory effect on the purified rat factor Xa, and immunodepletion of C1 inhibitor from the fractionated plasma attenuated the inhibitory effect

CONCLUSION

These results suggest that SHR-SP get into a hypocoagulable state rather than a hypercoagulable state, and that the reduction of factor Xa activity in SHR-SP may be related to the elevation of C1 inhibitor activity.

Fibrinolytic/hemostatic variables in arterial hypertension: response to treatment with irbesartan or atenolol

Essential hypertension is often accompanied by abnormalities of the coagulation/fibrinolytic system, predisposing to a procoagulant state. The aim of the present study was to compare the effects of atenolol (beta1-blocker agent) and irbesartan (angiotensin II type 1 receptor antagonist) on plasma levels of hemostatic/fibrinolytic and endothelial function markers in a cohort of previously untreated hypertensives. Fifty-four patients were randomly assigned to atenolol 25 to 150 mg (26 patients) or irbesartan 75 to 300 mg (28 patients). The plasma levels of plasminogen activator inhibitor-1 antigen, thrombomodulin, tissue factor pathway inhibitor antigen, fibrinogen, and factor XII were determined before and after 6 months of therapy. Age, gender distribution, body mass index, lipid profile, and baseline values of the measured markers were similar in both groups. Baseline values for systolic and diastolic blood pressure, as well as the reduction after treatment, were not significantly different between the two groups. Treatment with irbesartan was associated with a significant decrease in the levels of all the parameters. Similar findings were observed in the atenolol group, except for factor XII and tissue factor pathway inhibitor levels, which were not significantly decreased in this group. The reduction, however, of fibrinogen, plasminogen activator inhibitor-1, and thrombomodulin was significantly greater in the irbesartan than in the atenolol group. In conclusion, the results indicated that, despite an equally controlled blood pressure, 6-month therapy with irbesartan was associated with a more favorable modification of hemostatic/fibrinolytic status than atenolol.

Endogenous fibrinolysis in patients with lower extremity ischemia

To explore the relationship between disorders of endogenous fibrinolysis and thrombosis in patients with lower extremity ischemia, we measured the activity of tissue plasminogen activator (tPAac) and plasminogen activator inhibitor (PAlac) and the antigens of tissue plasminogen activator (tPAa) and inhibitor (PAla) in plasma from 420 patients treated for lower extremity ischemia. Values and ratios observed were compared with those in healthy volunteers. Additionally, values and ratios in the patients were examined with respect to the severity of ischemia and site of atherosclerotic occlusion or stenosis (pelvic compared with femoropopliteal or crural). Patients with lower extremity ischemia had higher plasma concentrations of PAla (p<0.01) and PAlac (p<0.0001) than healthy volunteers. In patients with rest pain or gangrene, the ratio of tPAac to PAlac was higher than in patients with claudication (p<0.05). The elevation of tPAac in patients with the more severe form of lower extremity ischemia is probably the feedback protective reaction on prothrombotic mechanisms of the organism suffered from severe atherosclerosis. Results did not vary according to the site of occlusion or stenosis. Our study found defects in endogenous fibrinolysis in patients with lower extremity ischemia. A defect in fibrinolysis may contribute to the development of thrombosis in native arteries and bypasses.

Brain injury and cerebrovascular fibrin deposition correlate with reduced antithrombotic brain capillary functions in a hypertensive stroke model

Hemostasis factors may influence the pathophysiology of stroke. The role of brain hemostasis in ischemic hypertensive brain injury is not known. We studied ischemic injury in spontaneously hypertensive rats in relation to cerebrovascular fibrin deposition and activity of different hemostasis factors in brain microcirculation. In spontaneously hypertensive rats subjected to transient middle cerebral artery occlusion versus normotensive Wistar-Kyoto (W-K) rats, infarct and edema volumes were increased by 6.1-fold (P < 0.001) and 5.8-fold (P < 0.001), respectively, the cerebral blood flow (CBF) reduced during middle cerebral artery occlusion (MCAO) by 55% (P < 0.01), motor neurologic score increased by 6.9-fold (P < 0.01), and cerebrovascular fibrin deposition increased by 6.8-fold (P < 0.01). Under basal conditions, brain capillary protein C activation and tissue plasminogen activator activity were reduced in spontaneously hypertensive rats compared with Wistar-Kyoto rats by 11.8-fold (P < 0.001) and 5.1-fold (P < 0.001), respectively, and the plasminogen activator inhibitor-1 antigen and tissue factor activity were increased by 154-fold (P < 0.00001) and 74% (P < 0.01), respectively. We suggest that hypertension reduces antithrombotic mechanisms in brain microcirculation, which may enhance cerebrovascular fibrin deposition and microvascular obstructions during transient focal cerebral ischemia, which results in greater neuronal injury.

Relationships between fibrinogen and insulin resistance

A relationship between plasma fibrinogen levels and insulinemia, as well as the different parameters of the insulin resistance syndrome has been described. The aim of the present paper was to investigate whether plasma fibrinogen concentrations were linked to plasma insulin levels or to the degree of insulin resistance. For this purpose, 62 nondiabetic, nonhypertensive patients, 30 men and 32 women, with body mass indexes (BMIs) and ages ranging from 18.6 to 50.2 kg/m(2) and from 19 to 60 years, respectively, were studied. Insulin sensitivity was quantified by the minimal model procedure over a 180-min intravenous glucose tolerance test with iterative sampling. Plasma insulin was determined by radioimmunoassay without cross-reactivity to human proinsulin, and fibrinogen by the method of Clauss. Insulin sensitivity ranged from 0.009 to 23.2 min(-1)/(microU/ml)x10(-4), covering the whole range of insulin sensitivities. Fibrinogen ranged from 1.70 to 5.07 g/l. There was a significant negative correlation between fibrinogen and insulin sensitivity (r=-0.76,P<0.0001) and a positive correlation between fibrinogen and basal insulin (r=0.56,P<0.0001). After adjustment for BMI, body fat mass and waist-to-hip ratio, these two relationships remained significant. In addition, a multiple regression analysis was performed to assess the independent effect of the following related variables: fibrinogen, insulin sensitivity, insulinemia and BMI. Only insulin sensitivity appeared to account for the ability to predict fibrinogen values. Thus, we hypothesized it was likely that the state of insulin resistance rather than hyperinsulinemia per se was related to hyperfibrinogenemia. We proposed an interpretation of these data in connection with some factors like free fatty acids or tumor necrosis factor-alpha, which have been implicated in the pathogenesis of insulin resistance. Nevertheless, prospective and intervention studies are needed to assess whether there is a simple association or a causal relationship between insulin resistance and hyperfibrinogenemia.

Relationship between plasma plasminogen activator inhibitor 1 and insulin resistance

High plasminogen activator inhibitor 1 (PAI-1) levels are associated with an increased cardiovascular risk of atherothrombosis. Furthermore, increased plasma PAI-1 levels are associated with dyslipidemia, hyperinsulinemia and hypertension. This association between PAI-1 and metabolic components of the Metabolic Syndrome could explain the predisposition of insulin resistant patients to atherothrombosis. Recent studies have suggested that visceral adipose tissue might be the link between elevated plasma PAI-1 and insulin resistance in the Metabolic Syndrome. Indeed, visceral adipose tissue was proposed as a potentially important source of PAI-1 in humans. However, in light of recent studies, visceral adipose tissue appears to be involved in the increase of plasma PAI-1 via the metabolic disorders usually associated with central obesity, rather than directly. High plasma PAI-1 levels are undoubtedly related to insulin resistance, and the mechanisms which could explain such an increase in the Metabolic Syndrome appear to be multi-factorial and remain to be elucidated. These mechanisms may involve several metabolic disorders such as hyperinsulinemia, dyslipidemia, impaired glucose tolerance and hypertension, which would favor PAI-1 synthesis and release from different cell types.

Association of blood pressure with fibrinolytic potential in the Framingham offspring population

BACKGROUND

Hypertension is an established risk factor for acute coronary events. Because fibrinolytic and hemostatic factors are also associated with cardiovascular disease, we examined the relations of systolic and diastolic blood pressures (SBP and DBP) to levels of plasminogen activator inhibitor antigen, tissue plasminogen activator antigen, fibrinogen, factor VII, von Willebrand factor, fibrinogen, and plasma viscosity in subjects of the Framingham Offspring Study.

METHODS AND RESULTS

We studied 1193 men and 1459 women after the exclusion of subjects with known cardiovascular disease and those receiving anticoagulant or antihypertensive therapy. Linear regression models were used to evaluate SBP and DBP as predictors of fibrinolytic and hemostatic factor levels in separate sex models, with adjustment for age, body mass index, smoking, diabetes, total cholesterol, HDL, triglycerides, alcohol intake, and estrogen use (in women). In both sexes, levels of plasminogen activator inhibitor and tissue plasminogen activator antigen were positively related to SBP and DBP (P<0.001). Plasma viscosity was positively related to SBP (P=0.008) and DBP (P=0.001) in women only. There was no association between SBP or DBP and fibrinogen, factor VII, or von Willebrand factor in either sex.

CONCLUSIONS

These data suggest that impaired fibrinolysis may play an important role in the pathogenesis of cardiovascular disease in hypertensive patients.

Angiotensin-converting enzyme inhibitor prevents plasminogen activator inhibitor-1 expression in a rat model with cardiovascular remodeling induced by chronic inhibition of nitric oxide synthesis

Plasminogen activator inhibitor-1 (PAI-1) may participate in the development of cardiovascular remodeling by inhibiting extracellular matrix turnover and fibrinolysis. However, little is known about physiological regulators of PAI-1 in vivo. Angiotensin II has been shown to stimulate PAI-1 in vitro. We previously reported that long-term inhibition of nitric oxide (NO) synthesis with Nomega-nitro-L-arginine methyl ester (L-NAME) causes cardiovascular remodeling (vascular medial thickening and fibrosis) associated with increased tissue angiotensin-converting enzyme (ACE) activity. In the present study, we examined whether treatment with an ACE inhibitor modulates the cardiovascular PAI-1 expression in this model in vivo. Wistar-Kyoto rats were treated with either no drugs, L-NAME (100 mg/kg x day), or L-NAME plus the ACE inhibitor imidapril (20 mg/kg day). Marked increases in PAI-1 mRNA and protein levels in the aorta and left ventricle were observed after the first and fourth weeks of PAI-1 treatment. PAI-1 immunoreactivity was increased in the endothelium and the media of the aorta and coronary arteries after treatment of L-NAME. This increase in PAI-1 levels was associated with an increase in ACE activity of the aorta and left ventricle. ACE inhibition with imidapril significantly prevented both the increases in PAI-1 levels and the development of cardiovascular remodeling. These findings suggest that the local renin-angiotensin system regulates PAI-1 expression, and that the increased PAI-1 levels may contribute to the cardiovascular remodeling in this model.

Plasma plasminogen activator inhibitor 1, insulin resistance and android obesity

Plasma plasminogen activator inhibitor 1 (PAI-1) levels are elevated in insulin-resistant subjects and are associated with increased cardiovascular risk of atherothrombosis. Strong association between PAI-1 and the metabolic components of the insulin resistance syndrome is found in clinical studies, suggesting that insulin resistance may regulate circulating PAI-1. However, the mechanisms underlying increased PAI-1 levels in such conditions are still poorly understood. Several studies have been carried out specifically in patients with central or android obesity, a major characteristic of the insulin resistance syndrome, and have suggested that visceral adipose tissue may be the major component of the relationship between android obesity and PAI-1. Accordingly, adipose tissue PAI-1 production was found to be elevated in obese human subjects, particularly in visceral adipose tissue. The genetic background for having high PAI-1 levels in several populations have been looked for and its role appeared to be weaker than that of the metabolic condition. High plasma PAI-1 levels are then clearly related to android obesity and insulin resistance, but the mechanisms whereby PAI-1 increases in plasma in these diseases remain to be determined.

Insulin sensitivity and haemostatic factors in men at high and low cardiovascular risk. The Risk Factor Intervention Study Group

OBJECTIVE

To investigate the relationship between variables of the coagulation and fibrinolysis system and insulin sensitivity in non-diabetic men at high and low risk of cardiovascular disease.

DESIGN

Cross-sectional study.

SETTING

Outpatient clinic in city hospital.

PATIENTS

Thirty-five men at high risk for atherosclerotic disease (hypertension and at least one the following factors: hypercholesterolaemia and smoking) and an age-matched low-risk group (n = 23) with no cardiovascular risk factors.

MAIN OUTCOME MEASURES

Insulin-mediated glucose disposal (hyperinsulinaemic euglycaemic clamp) adjusted for lean body mass and fibrinogen, von Willebrand factor, prothrombin fragment 1 + 2, thrombin/antithrombin complex and plasminogen activator inhibitor activity were determined.

RESULTS

Insulin-mediated glucose disposal adjusted for lean body mass was significantly lower in the high-risk group than in the low-risk group. Glucose disposal was significantly negatively associated with plasminogen activator inhibitor activity (PAI) in the high-risk group and with von Willebrand factor in the low-risk group. In the whole study group, fibrinogen and PAI were significantly associated with glucose disposal. After adjusting for confounding factors, glucose disposal was independently negatively associated with PAI in the high-risk group (P < 0.001) and in the whole group (P < 0.001).

CONCLUSIONS

High-risk men were significantly more insulin-resistant than the low-risk group. Glucose disposal adjusted for lean body mass was associated with an impaired fibrinolytic activity in the high-risk group. Fibrinogen was associated with insulin resistance in the whole study group. The negative relationship between von Willebrand factor levels and glucose disposal in the low-risk group may indicate that insulin resistance can induce an endothelial dysfunction even in non-diabetic subjects.

Comparison of plasminogen activator inhibitor-1 concentration in insulin-resistant versus insulin-sensitive healthy women

The primary goal of this investigation was to see whether plasminogen activator inhibitor-1 (PAI-1) concentrations varied as a function of differences in insulin-mediated glucose disposal in 2 groups of healthy women matched for every other variable that might play a role in regulation of PAI-1. For this purpose, we recruited 32 healthy women, divided on the basis of their steady-state plasma glucose (SSPG) concentrations during the insulin suppression test into an insulin-resistant (SSPG=216+/-12 mg/dL, n=16) and an insulin-sensitive (94+/-6 mg/dL, n=16) group. PAI-1 antigen concentrations were significantly higher (26+/-4 versus 14+/-3 ng/mL, P<0.02) in the insulin-resistant group. In addition, fasting plasma insulin (18+/-3 versus 11+/-2 microU/mL, P<0.02) and triglyceride (160+/-19 versus 93+/-10 mg/dL, P<0.001) concentrations were higher in the insulin-resistant individuals, whereas HDL concentrations were lower (44+/-3 versus 58+/-3 mg/dL, P<0.005). However, the 2 groups were essentially identical in terms of age, menopausal status, hormone replacement therapy, body mass index (BMI), ratio of waist-to-hip girth, and blood pressure. When the experimental population was considered as 1 group, there were statistically significant correlations between PAI-1 antigen and the following variables: adjusting for differences in age and BMI, SSPG (r=0.56, P<0.001); triglyceride (r=0.39, P<0.05); and HDL cholesterol (r=-0. 65, P<0.001) concentrations. Finally, multiple regression analysis revealed the major determinants of PAI-1 to be insulin resistance, or insulin concentration, and HDL cholesterol. These results: 1) demonstrate that PAI-1 concentrations are higher in healthy, insulin-resistant women as compared with insulin-sensitive individuals, independent of differences in BMI or ratio of waist-to-hip girth; and 2) provide another mechanism by which insulin-resistant individuals are at increased thrombotic cardiovascular risk.

Local insulin infusion stimulates expression of plasminogen activator inhibitor-1 and tissue-type plasminogen activator in normal subjects

PURPOSE

Plasma levels of plasminogen activator inhibitor-1 are increased in obesity, hypertension, and diabetes. Their correlation with insulin levels supports the hypothesis that hypofibrinolysis may affect the development of atherosclerotic complications in patients with insulin resistance. To investigate the effect of insulin on fibrinolysis, we evaluated levels of plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (tPA) antigens during insulin infusion in the forearm vascular beds of 8 healthy subjects.

MATERIALS AND METHODS

Insulin was infused in the brachial artery of each subject to raise local venous concentrations to approximately 100 microU/mL. Blood samples were obtained from the brachial artery and vein at baseline, after 30, 60, 90, and 120 minutes of infusion, and 30 minutes after the end of the infusion.

RESULTS

Following intra-arterial infusion of insulin, forearm blood flow (mean +/- SD) increased progressively from 2.7 +/- 0.6 to 4.0 +/- 0.6 mL/dL/min (P <0.01) and did not return to baseline after the end of the infusion. Plasminogen activator inhibitor-1 balance increased (345 +/- 160 versus 8 +/- 152 fmol/dL/min, P <0.02) at 60 minutes, reaching baseline levels after the end of the infusion. After 90 minutes, tPA balance increased (40 +/- 26 versus 7 +/- 29 fmol/dL/min, P <0.01) with a profile similar to forearm blood flow.

CONCLUSIONS

Local hyperinsulinemia induces regional vasodilation and expression of PAI-1 and tPA antigens. An alteration of this physiological process could be involved in the development of hypofibrinolysis and atherosclerosis in states of insulin resistance.

Rapid, Homogeneous Genotyping of the 4G/5G Polymorphism in the Promoter Region of the PAI1 Gene by Fluorescence Resonance Energy Transfer and Probe Melting Curves

Background: Many studies have convincingly shown that survivors of myocardial infarction have impaired fibrinolytic activity because of increased concentrations of plasma plasminogen activator inhibitor-1 (PAI-1). A single guanosine insertion/deletion polymorphism in the promoter region of the PAI1 gene, commonly called 4G/5G, has been shown to be associated with plasma PAI-1 activity. Our aim was to develop and validate a homogeneous assay for rapid genotyping of the 4G/5G polymorphism.

Methods: In this report we present a single-tube method for genotyping of the 4G/5G polymorphism that combines both rapid-cycle PCR with real-time monitoring of the amplification process and generation of allele-specific fluorescent probe melting profiles on the LightCyclerTM. Two fluorescently labeled hybridization probes recognizing adjacent sequences in the amplicon were present in the reaction mixture. The shorter detection probe spanned the polymorphic site, perfectly matching the 5G allele. After annealing, the fluorophores were in resonance energy transfer, providing real-time monitoring of the amplification process. At the completion of the PCR, fluorescence was monitored as the temperature increased through the Tm of the probe/product duplex, and a characteristic melting profile for each genotype was obtained.

Results: With this method, 32 samples were genotyped within 30 min without the need of any post-PCR sample manipulation. The genotypes of 100 DNA samples determined with the LightCycler were identical to those obtained with conventional PCR and restriction fragment length analysis.

Conclusion: The genotyping of the 4G/5G polymorphism with the LightCycler is a rapid, reliable method that is suitable for typing both small and large numbers of samples.

Hyperinsulinemia in a normal population as a predictor of non-insulin-dependent diabetes mellitus, hypertension, and coronary heart disease: the Barilla factory revisited

The study was initiated to evaluate the ability of hyperinsulinemia (as a surrogate measure of insulin resistance) to predict the development in a previously healthy population of three putative outcomes of this abnormality--glucose intolerance, hypertension, and coronary heart disease (CHD). The study involved defining the incidence at which these changes occurred between 1981 and 1993 to 1996 in 647 individuals who were free of any disease when initially studied. The study population consisted of approximately 90% of the subjects evaluated in 1981, divided into quartiles on the basis of the plasma insulin response to a glucose challenge as determined in 1981. The results indicated that the 25% of the population with the highest insulin response in 1981 had significant (P < .001) increases in the incidence of impaired glucose tolerance (IGT) or type 2 diabetes (eightfold), hypertension (twofold), or CHD (threefold). Furthermore, the ability of hyperinsulinemia to predict the three clinical endpoints was independent of differences in age, gender, or body mass index (BMI). Finally, if CHD is considered the clinical endpoint, multiple logistic regression analysis indicates that the values for plasma triglyceride (TG) and mean arterial blood pressure ([MAP] as measured in 1981) also predict the development of CHD. These results indicate that the untoward clinical effects of insulin resistance and/or compensatory hyperinsulinemia, glucose intolerance, hypertension, and CHD clearly can develop in less than 15 years.

Clinical implications of elevated PAI-1 revisited: multiple arterial thrombosis in a patient with essential thrombocythemia and elevated plasminogen activator inhibitor-1 (PAI-1) levels: a case report and review of the literature

Plasminogen activator inhibitor (PAI-1), a member of the serine protein family, is the most active in vivo inhibitor of fibrinolysis induced by plasminogen, tissue plasminogen activator (tPA), and urokinase type plasminogen activator (uPA). While the association between elevated PAI-1 and thrombogenesis has been well studied for several disease processes, including coronary disease, postoperative deep vein thrombosis (DVT), myocardial infarction, malignancy, and diabetes, few studies have concentrated on the correlation between elevated PAI-1 levels and thrombogenesis in patients with myeloproliferative disorders. Essential thrombocythemia (ET), a chronic myeloproliferative disorder, characterized by the overproduction of poorly functioning platelets, is associated with both thrombotic and hemorrhagic life-threatening complications. Although the events resulting in thrombogenesis in such patients may be multifactorial in nature, an association between elevated PAI-1 levels and thrombus formation has been proposed. Herein we present a patient diagnosed with ET complicated by multiple episodes of arterial thrombosis. Elevations in PAI-1 levels were documented repeatedly. The role of elevated PAI-1 when associated with other disease processes is also discussed.

The effect of number of days in culture and plasminogen activator inhibitor-1 (PAI-1) 4G/5G genotype on PAI-1 antigen release by cultured human umbilical vein endothelial cells

An insertion/deletion (4G/5G) polymorphism in what has been shown to be an enhancer/repressor binding site in the promoter region of the PAI-1 gene has been related to plasma PAI-1 activity. Transfection studies demonstrated increased interleukin-1 stimulated PAI-1 synthesis in cells containing the 4G sequence. To study this response in endothelial cells, first passage HUVEC from 26 umbilical cords were stimulated with interleukin-1 and tumor necrosis factor-alpha. PAI-1 antigen was measured in 24-hour conditioned medium and allele-specific PCR utilized to determine genotype at the 4G/5G locus. Analysis of covariance was used to determine whether the effect of a variable time in culture was masking a difference between genotypes. A trend towards higher PAI-1 levels with increasing time in culture was observed. The geometric mean (95% confidence interval) of the basal rate of PAI-1 release was, 4G/4G 9.7 (7.0, 13.5) ng/24 hours (n=11), 4G/5G 9.5 (6.5, 13.9) ng/24 hours (n=9), and 5G/5G 10.9 (7.8, 15.1) ng/24 hours (n=6). In cells of the same cultures, the interleukin-1 stimulated levels were 25.9 (23.1, 29.1), 27.2 (23.6, 31.3), and 23.1 (19.5, 27.3) ng/24 hours, respectively, corresponding to ratios of stimulated to basal levels of 2.68, 2.87, and 2.12. After adjustment for time in culture the basal PAI-1 release was 4G/4G 10.7, 4G/5G 9.1, and 5G/5G 9.7 ng/24 hours. For interleukin-1 stimulated release the adjusted levels were 26.3, 27.0, and 22.7 ng/24 hours, respectively. Adjusted levels in 4G/4G genotype cells were non-significantly greater than those in cells of 5G/5G genotype by a factor of 1.16 (0.95, 4.08). This study did not demonstrate a significant difference in basal or cytokine stimulated PAI-1 release from cells of different PAI-1 promoter (4G/5G) genotypes but does not exclude increased interleukin-1 stimulated PAI-1 release in the 4G/4G compared with the 5G/5G genotype.

Visceral fat accumulation is an important determinant of PAI-1 levels in young, nonobese men and women: modulation by cross-sex hormone administration

Increased plasminogen activator inhibitor type-1 (PAI-1) levels, leading to impaired fibrinolysis, are associated with increased visceral fat in middle-aged and obese subjects. It is unknown, however, whether this association is independent of other disturbances clustered in the insulin resistance syndrome. We analyzed this association in young, nonobese transsexual men and women before and after administration of cross-sex steroids, which potentially influence many elements of the insulin resistance syndrome, including PAI-1 levels and visceral fat accumulation. We assessed the visceral fat area (by MRI); total body fat; insulin sensitivity (with a glucose clamp technique); and plasma levels of PAI-1, insulin, and triglycerides in young (<37 years old), nonobese (body mass index <28 kg/m2), healthy men (n=18) and women (n=15) before and after 12 months of cross-sex hormone administration. Men were treated with ethinyl estradiol 100 microgram/d plus cyproterone acetate 100 mg/d, and women were treated with testosterone esters 250 mg IM every 2 weeks. At baseline, only visceral fat area was significantly correlated with plasma PAI-1 levels in both men (r=0.57, P=0.03) and women (r=0.59, P=0.03). In multivariate linear regression analysis, this association was independent of total body fat, insulin sensitivity, and plasma levels of triglycerides and insulin. After 12 months of cross-sex hormone administration, the plasma PAI-1 levels were no longer correlated with visceral fat (which had increased). We conclude that in young, nonobese men and women, visceral fat area is an important determinant of plasma PAI-1 levels. After cross-sex hormone administration, this association was no longer demonstrable.

ACE inhibition but not angiotensin II antagonism reduces plasma fibrinogen and insulin resistance in overweight hypertensive patients

The aim of this study was to compare the effects of the angiotensin-converting enzyme (ACE) inhibitor perindopril and the angiotensin II antagonist losartan on insulin sensitivity and plasma fibrinogen in overweight hypertensive patients. Twenty-eight overweight mild to moderate [diastolic blood pressure (DBP) >90 and <110 mm Hg] hypertensives aged 43-64 years, after a 4-week placebo period, were randomized to perindopril, 4 mg o.d., or losartan, 50 mg o.d., for 6 weeks. Then, after a new placebo period, patients were crossed to the alternative regimen for further 6 weeks. At the end of the placebo and of the treatment periods, blood pressure was measured, plasma fibrinogen was evaluated, and insulin sensitivity was assessed by the euglycemic, hyperinsulinemic clamp technique. Glucose infusion rate (GIR) during the last 30 min of clamp and total glucose requirement (TGR) were evaluated. Both perindopril and losartan reduced SBP (by a mean of 20.2 mm Hg, p < 0.001 vs. placebo; and 15.8 mm Hg, p = 0.002 vs. placebo, respectively) and DBP (by a mean of 15.2 mm Hg, p = 0.001 vs. placebo, and 11.8 mm Hg, p = 0.01 vs. placebo respectively), with no difference between the two treatments. GIR was significantly increased by perindopril (+2.91 mg/min/kg, p = 0.042 vs. placebo), but not by losartan (+0.28 mg/min/kg, NS). TGR was not modified by losartan but was increased by perindopril (+9.3 g, p = 0.042 vs. placebo). Plasma fibrinogen levels were reduced by perindopril (-53.4 mg/dl, p = 0.022 vs. placebo) but not by losartan (-16.8 mg/dl, NS). The perindopril-induced decrease in fibrinogen was correlated with the increase in GIR (r = 0.39; p < 0.01). These findings suggest that fibrinogen decrease produced by the ACE inhibitor is related to its action on insulin sensitivity, which seems to be dependent not on angiotensin II blockade but rather on other mechanisms.

Growth hormone deficiency and cardiovascular risk

It is now recognized that growth hormone (GH) deficiency in adults represents a distinct clinical syndrome that encompasses reduced psychological well-being as well as specific metabolic abnormalities. The latter features, which include hypertension, central obesity, insulin resistance, dyslipidaemia and coagulopathy, closely resemble those of metabolic insulin resistance syndrome. The increased cardiovascular morbidity and mortality demonstrated in these GH-deficient (GHD) adults reinforce the close association between the two syndromes. Replacement of GH in GHD adults has resulted in a marked reduction of central obesity and significant reduction in total cholesterol but little change in other risk factors, in particular insulin resistance and dyslipidaemia. The persistent insulin resistance and dyslipidaemia, together with the elevation of plasma insulin levels and lipoprotein (a) with GH replacement in these subjects are of concern. Long-term follow-up data are required to assess the impact of GH replacement on the cardiovascular morbidity and mortality of GHD adults. Further exploration of the appropriateness of the GH dosage regimens currently being employed is also indicated.

Hemostasis in normotensive and hypertensive men: results of the PROCAM study. The prospective cardiovascular Münster study

BACKGROUND

The greater than normal cardiovascular risk of hypertensive patients could be partly due to an impairment of hemostatic balance found in such individuals.

OBJECTIVE

To examine the relationship between hemostatic variables and blood pressures in 1950 apparently healthy male participants in the prospective cardiovascular Münster study aged 40-65 years.

METHODS

Blood pressure and other variables were determined, including fibrinogen level, coagulation factor VII clotting activity, protein C level, antithrombin III level, plasminogen activator inhibitor-1 level, euglobulin fibrinolytic activity, and von Willebrand factor level.

RESULTS

Age-adjusted mean values of coagulation factor VII clotting activity, plasminogen activator inhibitor-1 level, antithrombin III level, and protein C level in hypertensives and borderline hypertensives were significantly higher than those in normotensive men (e.g. for hypertensive versus normotensive men, coagulation factor VII clotting factor activity 111.5 versus 106.1%, plasminogen activator inhibitor-1 level 5.05 versus 3.22 arbitrary units/ml, and protein C level 111.1 versus 107.0%, P < 0.05-0.01). For most of the hemostatic variables we found positive bivariate correlations to blood pressure (P < or = 0.05). Exceptions were von Willebrand factor level (no correlation to blood pressure), and euglobulin fibrinolytic activity (a negative correlation to systolic blood pressure and no correlation to diastolic blood pressure). Significance persisted in the multiple logistic regression analysis with the exception of the relationships between systolic and diastolic blood pressures and fibrinogen level as well as euglobin fibrinolytic activity after adjustment for age. After adjustment for age and body mass index significance for relationships between systolic blood pressure and coagulation factor VII clotting activity as well as protein C level was also lost.

CONCLUSIONS

We conclude that the greater than normal cardiovascular risk of hypertensive patients is partly due to an imbalance in hemostasis.

Fibrinogen and cardiovascular risk

The hypothesis that fibrinogen is closely related to cardiovascular risk has been strengthened through the results of various lines of research, which this review will aim to unravel. Several prospective epidemiological studies convincingly show elevated fibrinogen to represent a major, independent cardiovascular risk factor. Cross-sectional studies strongly associate fibrinogen and conventional cardiovascular risk factors. Clinical cohort studies demonstrate that increased fibrinogen is also a risk factor for the sequelae of cardiovascular disease. Our knowledge about the determinants of the variable plasma level of fibrinogen in health and disease is incomplete. Understanding of the mechanisms that might be involved in the atherothrombogenic action of fibrinogen is also fragmentary. Fibrinogen strongly affects blood coagulation, blood rheology and platelet aggregation. In addition, it has direct effects on the vascular wall and is a prominent acute phase reactant. All of these phenomena might constitute pathophysiological mechanisms involved in the association between fibrinogen and cardiovascular events. Their relative importance is unclear at present. Even though many crucial questions await conclusive answers, little doubt exists that fibrinogen represents a major, independent risk factor.

Systolic and diastolic blood pressure related to six other risk parameters in Turkish adults: strong correlation with relative weight

This study aimed to investigate the relationship of systolic and diastolic blood pressure (BP) with a series of metabolic and nonmetabolic cardiovascular risk variables in a random sample of Turkish general adult population. Values of systolic and diastolic BP on the one hand and of six variables including body mass index (BMI), waist/hip ratio (W/H), grade of physical activity (PhA), plasma lipids and cigarette smoking from 1046 men and 1095 women aged 225 years were included in the analysis. Participants were classified into tertiles according to systolic and diastolic BP measurements, and were stratified in two age categories: 25-44 years (young) and 45-74 years (elderly). Plasma total cholesterol and triglyceride (Trg) concentrations were measured by the enzymatic method with the Reflotron apparatus. In multiple regression analysis, age proved the strongest independent determinant of BP. BMI was a strong independent marker of systolic and diastolic pressures in women, while in men the determinant value of the W/H was equivalent to BMI. For each increment of 1 kg/m2 of BMI was associated in men an increase of over 8 and 16 mmHg in diastolic and systolic pressure, respectively, regardless of age group. Corresponding figures in women were roughly 6 and 10 mmHg. Though plasma Trg were not independently associated with BP in either gender, the independent contribution of plasma cholesterol level in women to systolic and diastolic pressures was small but significant. BP was related to mean concentrations of plasma Trg in young adults only, total cholesterol levels were associated with diastolic pressure in young men only, whereas PhA grade was not associated with BP. These findings are consistent with the theory that, in the normal state, functions such as regulation of BP, body weight and lipid metabolism are closely linked to each other.

Plasminogen activator inhibitor-1 activity is independently related to both insulin sensitivity and serum triglycerides in 70-year-old men

Increased levels of plasminogen activator inhibitor-1 (PAI-1) have been discussed as a part of the insulin resistance syndrome. However, it is not clear whether the relationship between PAI-1 and insulin resistance is independent of or mediated by increased triglycerides levels. The aim of this study was to investigate whether PAI-1 activity is associated with insulin sensitivity independently of serum triglycerides (sTG) and of other potential confounders. Seventy-year-old men (n=871), participating in a cohort study undergoing extensive metabolic investigations, had blood samples taken for determination of PAI-1 activity. Insulin sensitivity was determined by the euglycemic hyperinsulinemic clamp. In multivariate correlation and regression analyses, insulin sensitivity was a statistically significant determinant of PAI-1 activity (partial r=-.12; P<.001), independent of sTG, body mass index, waist-hip ratio, and other potential confounders. The levels of sTG were also independently related to PAI-1 activity (partial r=.18; P<.001). The relationships between PAI-1 and insulin sensitivity and sTG were independent of fasting glucose levels. Aggregation of risk factors of the insulin resistance syndrome was associated with increased activity of PAI-1 in men with normal glucose tolerance. We conclude that PAI-1 activity is related to insulin sensitivity and sTG, independently of each other and of other potential confounders, and that increased levels of PAI-1 should be regarded as a component of the insulin resistance syndrome.