Fibrinolysis and risk of coronary artery disease

Does stress hyperglycemia affect mortality? Acute myocardial infarction - case control study

Introduction

We aimed to investigate the effect of stress (acute) hyperglycemia in patients with acute coronary syndrome who had not been previously diagnosed with diabetes mellitus (DM) on the prognosis of the disease in terms of mortality.

Material and methods

Patients who were admitted to the Adana Numune Training and Research Hospital Emergency Service Clinic between August 2010 and August 2013 and whose plasma blood glucose level was over 140 mg/dl at the time of admission but were not previously diagnosed with DM, who were over the age of 18 and considered to have acute myocardial infarction were included.

Results

A total of 259 patients whose data were fully attainable were included in the study. 80.3% (n = 208) of the patients were male and 19.7% (n = 41) were female. Non-ST elevation myocardial infarction was found in 71.6%, ST elevation myocardial infarction was found in 28.4% of the patients with stress hyperglycemia. It was determined that 10.1% of patients with stress-related hyperglycemia and 1.3% of patients without stress-related hyperglycemia had died.

Conclusions

The plasma blood glucose level at presentation of patients diagnosed with acute myocardial infarction at the emergency room is associated with early in-hospital mortality.

Fibrinolytic effects of peroneal nerve stimulation in patients with lower limb vascular disease

Patients with lower limb vascular disease are at an increased risk of thrombotic events. Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) are important components of the fibrinolytic system, responsible for clot lysis. This study aimed to establish whether peroneal nerve stimulation (PNS) could promote fibrinolysis within a cohort of vascular patients. Ethical approval was obtained for this prospective case-controlled study. Patients were randomly assigned to active stimulation or control groups. Arterial flow measurements and venous blood samples were taken bilaterally at baseline and following 45 min of PNS. ELISA analysis for plasma t-PA and PAI-1 was performed utilizing commercially available kits. Statistical analysis evaluated the changes in t-PA and PAI-1 levels from baseline for the active (device active), passive (contralateral limb) and control limbs (inactive device applied).Seventy-seven participants were recruited: 30 claudicants (25 active and five controls), 25 patients postoperative infra-inguinal bypass grafts (19 active and six controls) and 22 patients with varicose veins (17 active and five controls). t-PA levels reduced significantly in all groups; however, intergroup analysis demonstrated no statistically significant difference when comparing the active, passive and control limbs (P = 0.079). PAI-1 levels decreased by 16.2% (34.0 ng/ml, SD 52.2) in the active limbs but only 3.6% (11.4 ng/ml, SD 47.4) and 2.6% (2.7 ng/ml, SD 21.3) in the passive and control limbs, respectively (intergroup analysis P < 0.001). No relationship between changes in flow and plasma of t-PA and PAI-1 were demonstrated. Peroneal nerve stimulation may augment fibrinolysis by decreasing plasma levels of PAI-1 levels in patients with lower limb arterial and venous disease.

Tissue plasminogen activator, von Willebrand factor, and risk of type 2 diabetes in older men

OBJECTIVE

The objective of this study was to assess the relationship between putative markers of endothelial dysfunction (tissue plasminogen activator [t-PA] antigen and von Willebrand factor [vWF] antigen) and development of type 2 diabetes, as well as the role of inflammation, adipokines, hepatic function, and insulin resistance in modifying these relationships.

RESEARCH DESIGN AND METHODS

This was a prospective study of 3,562 nondiabetic men aged 60-79 years followed up for an average of 7 years during which there were 162 incident cases of type 2 diabetes.

RESULTS

Elevated t-PA (top third) was associated with a near threefold increase in risk of diabetes compared with the risk in those in the bottom third after adjustment for lifestyle factors and waist circumference (relative risk [RR] 2.98 [95%CI 1.79-5.00]; P(trend) < 0.0001); weaker but significant (marginal) associations were seen with vWF (1.24 [0.83-1.85]; P = 0.05 for trend). Both biomarkers of endothelial dysfunction correlated significantly with markers of inflammation (interleukin-6 [IL-6] and C-reactive protein [CRP]), hepatic function (gamma-glutamyl transferase [GGT]), and insulin resistance, with t-PA showing stronger associations with adiposity, hepatic function, and insulin resistance than vWF. t-PA was also significantly and inversely associated with adiponectin. Adjustment for IL-6, adiponectin, and GGT attenuated the association of incident diabetes with vWF (1.06 [0.71-1.60]), but the relationship seen with t-PA remained significant (adjusted RR 2.19 [1.29-3.70]). Subsequent adjustment for insulin attenuated the association further, but t-PA was still associated with a significant increase in risk (1.66 [0.96-2.85]; P(trend) = 0.02).

CONCLUSION

t-PA antigen, but not vWF antigen, is independently associated with risk of type 2 diabetes.

Physiological testosterone stimulates tissue plasminogen activator and tissue factor pathway inhibitor and inhibits plasminogen activator inhibitor type 1 release in endothelial cells

There is a striking gender difference in atherosclerotic vascular disease. For decades, testosterone was considered detrimental to the cardiovascular system. Recent studies, however, have presented some alternative results. The aim of this study was to evaluate the effect of testosterone, using physiological and supraphysiological concentrations, on antigen and mRNA levels of tissue plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), and tissue factor pathway inhibitor (TFPI) released by human umbilical vein endothelial cells and to investigate the cellular mechanism. Cells within 2-3 passages were cultured in 25 cm(2) flasks or plated onto 96-well plates with a density of about 1 x 10(5) cells/mL as recommended. The cells were incubated in the presence or absence of testosterone (3, 30, 3 x 10(3), 3 x 10(4) nmol/L) for 48 h. Levels of tPA, PAI-1, and TFPI antigen were assayed with ELISA kits. Reverse transcriptase PCR was carried out to detect tPA, PAI-1, and TFPI mRNA levels. Cells were incubated in androgen-receptor antagonist (flutamide 10 micromol/L) or aromatase inhibitor (aminoglutethimide 50 micromol/L) for 3 h, and then the experiments were repeated. Testosterone at a physiologic concentration (30 nmol/L) increased the antigen levels of tPA and TFPI significantly (P < 0.05). However, tPA and TFPI levels were markedly reduced (P < 0.05) at a larger dose (3 x 10(4) nmol/L). On the other hand, PAI-1 antigen levels decreased significantly at the testosterone concentrations ranging from 3 to 3 x 10(4) nmol/L (P < 0.05). The change in the levels of tPA and TFPI were reflected in the corresponding change in mRNA levels. Flutamide attenuated the effect of testosterone at physiological concentration (30 nmol/L). The results demonstrated that testosterone at physiological concentrations may have a beneficial influence on the haemostatic system through enhancement of anticoagulant activity, resulting from stimulation of TFPI and tPA expression and inhibition of PAI-1 secretion by the endothelium.

Central obesity and the metabolic syndrome: implications for primary care providers

PURPOSE

To describe screening measures that will determine which clients are at risk for the metabolic syndrome, common manifestations of the syndrome, preventive diagnostic considerations, and management and treatment options that primary care providers can implement.

DATA SOURCES

Review of the clinical and research literature, supplemented with specific diagnostic criteria.

CONCLUSIONS

Central obesity is the cornerstone of the metabolic syndrome, which may lead to type 2 diabetes and cardiovascular disease. Generalized obesity is defined as body weight that is considerably greater than the ideal weight and that is distributed on all parts of the body. Generalized obesity has long been considered a significant risk factor for developing type 2 diabetes and cardiovascular disease. Those clients of ideal body weight have been considered at less risk for developing these conditions. However, this perception may not always be accurate. Weight distribution plays a major role in acquiring the metabolic syndrome. Because waist circumference is as important as overall body weight, central obesity is key to determining the risk.

IMPLICATIONS FOR PRACTICE

The metabolic syndrome has now been given a CPT code (277.7). It is more likely that clients at risk for or with the metabolic syndrome may first be seen by a primary care provider. Primary care providers need to be able to diagnose, treat, and provide preventive interventions for the metabolic syndrome. Clients at risk will likely be identified during routine health screening. Early detection of and interventions focused on the metabolic syndrome may reduce the occurrence of type 2 diabetes and cardiovascular disease. Use of a tape measure to determine waist circumference may help the provider to identify at-risk clients who are of normal weight, and thus not previously believed to be at risk, as well as those more obviously at risk. It is necessary to determine not only patients' overall body weight but also their waist circumference. A measuring tape may be the key tool for establishing a patient's early risk for the metabolic syndrome and, ultimately, for prevention of type 2 diabetes and cardiovascular disease.

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.

Plasma fibrinolytic capacity in renal transplant recipients: effect of steroid-free immunosuppression therapy

BACKGROUND

Cardiovascular disease is the most common cause of death among renal transplant recipients (RTRs). Impaired fibrinolytic capacity caused by an increase in plasminogen activator inhibitor type 1 (PAI-1) levels is involved in the onset of atherosclerosis and thrombotic complications. Long-term steroid treatment may induce arterial hypertension and metabolic and prothrombotic changes (including up-regulation of PAI-1 synthesis), which increase the cardiovascular risk. We evaluated plasma fibrinolytic behavior in two groups of RTRs treated with different immunosuppressive regimens.

METHODS

Twenty-seven RTRs were randomized to receive long-term (17 patients) or perioperative short-term (10 patients) steroids in addition to immunosuppression with cyclosporine A plus everolimus (Certican; Novartis, Basel, Switzerland) (7 patients) or FK506 plus mycophenolate mofetil (20 patients). In each patient, fibrinolytic capacity was studied with the 20-min venous occlusion test 1 and 6 months after transplantation. The following were assayed: euglobulin lysis time, tissue-type plasminogen activator antigen, and PAI-1 antigen and activity.

RESULTS

One month after transplantation, a severe impairment of fibrinolytic capacity, mainly caused by an increase in PAI-1 antigen and activity levels, was seen in patients with and without steroid treatment. Six months after transplantation, an improvement in fibrinolytic potential as the result of a decrease in PAI-1 levels was observed only in patients without steroid therapy. None of the steroid-treated patients demonstrated PAI-1 values correlating with body mass index, blood pressure, and metabolic parameters, thus confirming the effect of exogenous factors on PAI-1 expression. Moreover, all patients revealed a slight impairment of stimulated endothelial tissue-type plasminogen activator release, regardless of any steroid treatment, which was probably attributable to calcineurin inhibitor-induced endothelial dysfunction.

CONCLUSIONS

Our study suggests that steroid-free immunosuppression is associated with a better fibrinolytic capacity in RTRs. This finding may contribute toward reducing the risk of cardiovascular events.

Trends in coronary risk factors in the WHO MONICA project

BACKGROUND

The World Health Organization (WHO) MONICA Project was established to determine how trends in event rates for coronary heart disease (CHD) and, optionally, stroke were related to trends in classic coronary risk factors. Risk factors were therefore monitored over ten years across 38 populations from 21 countries in four continents (overall period covered: 1979-1996).

METHODS

A standard protocol was applied across participating centres, in at least two, and usually three, independent surveys conducted on random samples of the study populations, well separated within the 10-year study period.

RESULTS

Smoking rates decreased in most male populations (35-64 years) but in females the majority showed increases. Systolic blood pressure showed decreasing trends in the majority of centres in both sexes. Mean levels of cholesterol generally showed downward trends, which, although the changes were small, had large effects on risk. There was a trend of increasing body mass index (BMI) with half the female populations and two-thirds of the male populations showing a significant increase.

CONCLUSIONS

It is feasible to monitor the classic CHD risk factors in diverse populations through repeated surveys over a decade. In general, the risk factor trends are downwards in most populations but in particular, an increase in smoking in women in many populations and increasing BMI, especially in men, are worrying findings with significant public health implications.

The molecular basis for anti-proteolytic and non-proteolytic functions of plasminogen activator inhibitor type-1: roles of the reactive centre loop, the shutter region, the flexible joint region and the small serpin fragment

The serine proteinase inhibitor plasminogen activator inhibitor type-1 (PAI-1) is the primary physiological inhibitor of the tissue-type and the urokinase-type plasminogen activator (tPA and uPA, respectively) and as such an important regulator of proteolytic events taking place in the circulation and in the extracellular matrix. Moreover, a few non-proteolytic functions have been ascribed to PAI-1, mediated by its interaction with vitronectin or the interaction between the uPA-PAI-1 complex bound to the uPA receptor and members of the low density lipoprotein receptor family. PAI-1 belongs to the serpin family, characterised by an unusual conformational flexibility, which governs its molecular interactions. In this review we describe the anti-proteolytic and non-proteolytic functions of PAI-1 from both a biological and a biochemical point of view. We will relate the various biological roles of PAI-1 to its biochemistry in general and to the different conformations of PAI-1 in particular. We put emphasis on the intramolecular rearrangements of PAI-1 that are required for its antiproteolytic as well as its non-proteolytic functions.

Potential role of recombinant annexin II in diabetic vascular injury

Hyperinsulinemia and hyperglycemia have been associated with vascular injury such as atherosclerosis in diabetes mellitus. Recently, annexin II, a member of annexin family proteins, has been found to work as co-receptor on endothelial cells for plasminogen and tissue plasminogen activator, facilitating plasmin generation on the surface of vascular endothelium. In this review, we overviewed the effect of glucose and insulin on plasmin generation in endothelial cells and its potential modulation by recombinant annexin II (rAN II) based on our data.

Importance of the amino-acid composition of the shutter region of plasminogen activator inhibitor-1 for its transitions to latent and substrate forms

The serpins are of general protein chemical interest due to their ability to undergo a large conformational change consisting of the insertion of the reactive centre loop (RCL), which becomes strand 4, into the central beta sheet A. To make space for the incoming RCL, the 'shutter region' opens by the beta strands 3A and 5A sliding apart over the underlying alpha helix B. Loop insertion occurs during the formation of complexes of serpins with their target serine proteinases and during latency transition. This type of loop insertion is unique to plasminogen activator inhibitor-1 (PAI-1). We report here that amino-acid substitutions in a buried cluster of three residues forming a hydrogen bonding network in the shutter region drastically accelerate PAI-1 latency transition; that the rate was in all cases normalized by the PAI-1 binding protein vitronectin; and that substitution of an adjacent beta strand 5A Lys residue, believed to anchor beta strand 5A to other secondary structural elements, had differential effects on the rates of latency transition in the absence and the presence of vitronectin, respectively. An overlapping, but not identical set of substitutions resulted in an increased tendency to substrate behaviour of PAI-1 at reaction with its target proteinases. These findings show that vitronectin regulates the movements of the RCL through conformational changes of the shutter region and beta strand 5A, are in agreement with RCL insertion proceeding by different routes during latency transition and complex formation, and contribute to the biochemical basis for the potential use of PAI-1 as a therapeutic target in cancer and cardiovascular diseases.

Reciprocal regulation of tissue-type and urokinase-type plasminogen activators in the differentiation of murine preadipocyte line 3T3-L1 and the hormonal regulation of fibrinolytic factors in the mature adipocytes

Adipose tissue expresses a variety of genes including tumor necrosis factor alpha and type-1 plasminogen activator inhibitor (PAI-1); and these factors, produced by adipocytes, may be associated with the risk of coronary events in obesity. In this study, we characterized the production of fibrinolytic factors including tissue-type plasminogen activator (tPA), urokinase-type PA (uPA), and PAI-1 in the differentiation of preadipocytes, and examined the hormonal regulation of these fibrinolytic factors in mature adipocytes. Mouse 3T3-L1 preadipocytes were employed as a model of adipocytes. Adipocyte differentiation was induced by insulin, dexamethasone, and 3-isobutyl-1-methyl xanthine (IBMX). alpha-Glycerophosphate dehydrogenase (GPDH) activity and glucose transporter 4 (GLUT4) mRNA, indices for adipocyte maturation, were induced on Day 4, and gradually increased. GPDH activity reached its maximum level on Day 14. The level of tPA, a major PA in preadipocytes, dramatically decreased with differentiation. On the other hand, that of uPA reciprocally increased. PAI-1 production was also dramatically induced concomitant with differentiation. In mature adipocytes, uPA production was dominant (25 microg/ml/24 h vs. 0.8 microg/ml/24 h for tPA). Total PA activity in the mature adipocytes was reduced by insulin or dexamethasone, but not by glucagon. Insulin, IBMX, and dexamethasone significantly decreased both uPA and tPA production, and increased PAI-1 production. Glucagon had no effect on the production of these fibrinolytic factors. Our results reveal that uPA is one of the markers for the differentiation of 3T3-L1 cells and that insulin, IBMX, and dexamethasone are potent regulators of the fibrinolytic activity in differentiated 3T3-L1 cells, reciprocally affecting PA and PAI-1 levels in them.

Plasminogen binding is increased with adipocyte differentiation

The purpose of this study was to examine the role of the plasminogen system in the development of adipose tissue. Plasminogen binding capacity was determined in differentiated and undifferentiated cells from adipose tissue of plasminogen deficient mice and 3T3 cells, a well-characterized tissue culture model. In 3T3 cells, plasminogen binding was fivefold higher in differentiated cells compared to the undifferentiated cells. Inhibition of binding by carboxyl-terminal lysine analogs was similar for the differentiated and undifferentiated cells with tranexamic acid > EACA > lysine. The binding of plasminogen was concentration-dependent and approaches saturation in the both cell types. The number of plasminogen binding sites was tenfold higher in the differentiated compared to the undifferentiated cells. In isolated mature fat cells and stromal cell cultures from mouse adipose tissue, plasminogen binding was also higher in the differentiated mature fat cells and differentiated stromal cells compared to undifferentiated stromal cells. Plasminogen binding was elevated in the differentiated cells from the Plg-/- mice compared to cells from the WT mice. These results suggest that the plasminogen system plays an important role in adipose tissue development.

Acute inhibitory effect of alcohol on fibrinolysis

In contrast to a reduced risk of coronary heart disease (CHD) with light to moderate alcohol consumption, heavy alcohol intake and binge drinking are associated with increased cardiovascular mortality. Alcohol has an acute and profound effect on fibrinolysis that may be relevant to the pathogenesis of CHD. The short-term effects of a low (two glasses, 250 mL, 20 g ethanol) and a high (six glasses, 750 mL, 60 g ethanol) intake of red wine were studied in male volunteers and compared to the intake of mineral water. To find a threshold for inhibition of fibrinolysis and to study a binge effect, a second experiment was performed comparing the intake of four (500 mL, 40 g ethanol) and eight (1000 mL, 80 g ethanol) glasses of red wine with mineral water. Plasminogen activator inhibitor-1 (PAI-1), tissue-type plasminogen activator (t-PA), plasmin-antiplasmin (PAP) complexes and clot lysis time were measured. In contrast to the circadian rhythm with an enhanced fibrinolysis in the evening that was found in the mineral water group, an intake above four glasses of wine inhibited fibrinolysis significantly. After the intake of two glasses no significant disturbance of the circadian rhythm was observed. Five hours after the consumption of six glasses of wine, a dramatic increase occurred of PAI-1 antigen (77 +/- 42 microg L-1 vs. - 5 +/- 10 microg L-1 in the mineral water controls; P < 0.001) and PAI-1 activity (27 +/- 15 U mL-1 vs. - 2 +/- 3 U mL-1 in mineral water controls; P < 0.001). Despite a rise in t-PA antigen, t-PA activity dropped (- 0.5 +/- 0.2 U mL-1 vs. - 0.1 +/- 0.2 in controls; P < 0.001) as did PAP complexes (- 103 +/- 55 microg L-1 vs. - 26 +/- 57 microg L-1 in controls; P < 0.01). After the consumption of eight glasses of wine, the clot lysis assay indicated continued inhibition of fibrinolysis the following morning. Drinking a large amount of alcohol in the evening results in an acute inhibition of fibrinolysis, persisting the following morning. This may predispose to accelerated atherosclerosis and set the stage for thrombotic coronary events, explaining the higher cardiovascular mortality risk in binge drinkers.

Relationship between fibrinolytic and metabolic variables: a study in patients attending a lipid clinic

We investigated the relationship between plasma levels of metabolic and fibrinolytic variables in 163 fasted patients attending a lipid clinic. Of these patients, 118 had hypertriglyceridaemia (HTG) and 45 had normotriglyceridaemia (NTG). In HTG, basal fibrinolytic activity, ie tissue plasminogen activator (t-PA) activity, was impaired as a result of high plasminogen activator inhibitor type 1 (PAI-1) antigen and activity. Multiple stepwise regression analysis identified insulin and triglyceride levels as independent determinants of plasma PAI-1 levels (R2 = 0.18; P = 0.0001). When the patients were stratified into tertiles according to their levels of triglyceride and insulin, PAI-1 antigen levels were found to increase with rising levels of triglyceride in each insulin tertile. In contrast, the increase of PAI-1 with rising insulin levels was evident in the highest triglyceride tertile. In addition, subjects in the lowest tertile of both triglyceride and insulin had the lowest PAI-1 antigen levels, and subjects in the highest tertile of both triglyceride and insulin had the highest levels of PAI-1. Both basal and stimulated levels of t-PA antigen were significantly higher in HTG than in NTG. Multiple stepwise regression analysis identified triglyceride level as the sole major determinant of t-PA antigen levels (R2 = 0.13; P = 0.00003). The observation that both insulin and triglycerides correlate with PAI-1, whereas triglycerides were involved only in the increased secretion of t-PA, suggests that these two proteins are regulated by different mechanisms.

Effects of gemfibrozil on insulin sensitivity and on haemostatic variables in hypertriglyceridemic patients

In order to assess the efficacy of gemfibrozil on lipid and haemostatic parameters in patients with plurimetabolic syndrome, a multicenter double-blind placebo controlled, parallel study was carried out in 56 patients with primary hypertriglyceridemia and glucose intolerance. These patients had elevated PAI activity and antigen and t-PA antigen levels at rest and after venous occlusion. Gemfibrozil reduced plasma triglyceride levels (P<0.001), whereas it increased free fatty acids (P<0.05) and high density lipoprotein cholesterol levels (P<0.05). In those patients reaching normalization of plasma triglyceride levels (triglyceride reduction > or =50%) (n=15), insulin levels (P<0.05) as well as the insulin resistance index were reduced by gemfibrozil treatment, suggesting an improvement of the insulin resistance index in this patient subgroup. Gemfibrozil treatment did not affect plasma fibrinolysis or fibrinogen levels, despite marked reduction of plasma triglycerides and improvement of the insulin sensitivity associated with triglyceride normalization.

Plasma leptin levels are associated with abnormal fibrinolysis in men and postmenopausal women

BACKGROUND

Leptin is a crucial mediator of satiety signals and energy balance, and its circulating levels are increased in obesity. It has recently been shown that plasma leptin levels in humans correlate with circulating insulin and to insulin secretion. This indicates that leptin may be an important link in metabolic consequences of the insulin resistance syndrome. Whether this includes abnormalities in fibrinolysis has not been studied.

METHODS AND RESULTS

Healthy subjects (n = 165; 85 men and 80 women) from the Northern Sweden MONICA population were investigated. Anthropometric measurements, oral glucose tolerance tests and sampling for plasma leptin, lipids, fibrinogen and fibrinolytic variables were made. Leptin levels were 342% higher in women than in men and were in both sexes strongly correlated to body mass index (BMI). After adjustments for age and BMI, leptin levels correlated significantly to pre/post glucoseload insulin levels in both sexes. After further adjustment for baseline insulin levels, leptin levels were in males significantly associated with increased waist circumference (P<0.001), low HDL cholesterol (P<0.05), low tPA activity (P<0.01) and high PAI-1 activity (P<0.001). In postmenopausal females, a significant association between leptin and low tPA activity/high PAI-1 activity was seen after adjustment for age and BMI (P<0.05). Conclusions. Circulating levels of leptin are associated with components of the insulin resistance syndrome, including defective fibrinolysis, in men and postmenopausal women. This suggests that leptin may be involved in the mediation of consequences of insulin resistance.