Tissue Plasminogen Activator Antigen Research Articles

Haemostatic factors and prediction of ischaemic heart disease and stroke in claudicants.

Thrombotic risk factors may be important in determining cardiovascular outcome in patients with symptomatic peripheral arterial disease. A cohort study with a 6-year follow-up period was established to determine the relationships between haemostatic and rheological factors and incident ischaemic heart disease (IHD) and stroke events in patients with peripheral arterial disease. A consecutive series of 607 patients with intermittent claudication was examined between 1989 and 1990 at the Peripheral Vascular Clinic, Royal Infirmary of Edinburgh. Main outcome measures were combined fatal and non-fatal stroke, non-fatal myocardial infarction (MI), coronary death and total coronary events. A total of 210 patients died during follow-up. 203 patients did not experience a vascular event or deterioration of limb ischaemia. Median levels of fibrinogen, von Willebrand factor (VWF), tissue plasminogen activator (t-PA) antigen, fibrin D-dimer and whole blood viscosity were significantly higher in those who experienced an event compared with those who did not. After adjusting for age and sex, fibrin D-dimer was significantly associated with risk of non-fatal myocardial infarction (RR 1.50, 95% CI 1.09-2.06, P < or = 0.01). Both fibrinogen and fibrin D-dimer were associated with risk of total coronary events (P < or = 0.05). The risk of stroke was related to baseline levels of t-PA antigen (RR 1.87, 95% CI 1.04-3.34, P < or = 0.05) and whole blood viscosity (RR 1.33, 95% CI 1.07-1.65, P < or = 0.01). All the relationships became weaker and statistically non-significant after further adjustment for cigarette smoking, systolic blood pressure, glucose and baseline IHD. The associations of these factors to IHD and stroke may therefore be partly related to cardiovascular risk factors, but are likely to be important in the pathogenesis of future atherothrombotic events in subjects with peripheral arterial disease.

Plasminogen Activator Inhibitor-1 and Angiotensin I Converting Enzyme Gene Polymorphism in Patients With Hypertension

Deletion polymorphism of angiotensin I-converting enzyme (ACE) gene has been reported to be an independent risk factor for myocardial infarction. Plasminogen activator inhibitor-1 (PAI-1) was proposed to be a link between the renin-angiotensin system and thrombotic risk. This study was undertaken to investigate the possible association between the insertion/deletion (I/D) polymorphism of the ACE gene and plasma PAI-1 levels in 160 patients with mild-to-moderate hypertension. The I/D genotypes were determined by polymerase chain reaction with oligonucleotide primers flanking the polymorphic region in intron 16 of the ACE gene. Baseline levels of PAI-1 antigen and activity and tissue plasminogen activator (t-PA) antigen were determined in fasting morning plasma samples. It was found that patients with homozygote deletion (DD, n = 37) ACE genotype did not have significantly higher plasma levels of PAI-1 antigen (31.2 ± 15.6 ng/mL v 28.4 ± 15.1 ng/mL or 27.2 ± 13.2 ng/mL, P = .42), PAI-1 activity (16.2 ± 10.6 IU/mL v 14.1 ± 9.4 IU/mL or 15.0 ± 9.9 IU/mL, P = .60), or t-PA antigen (14.6 ± 6.0 ng/mL v 13.4 ± 4.9 ng/mL or 14.6 ± 5.7 ng/mL, P = .40) as compared to those with heterozygote (DI, n = 67) or homozygote insertion (II, n = 56) genotypes. On multiple regression analysis, the ACE genotypes did not appear to be significant predictors for plasma PAI-1 levels and t-PA antigen after adjustment with age, sex, body mass index, plasma triglyceride, cholesterol, and glucose. In conclusion, the results indicated that the I/D polymorphism of the ACE gene was not related to plasma PAI-1 levels in a Chinese population with hypertension. The ACE genotypes may not have a role in influencing the fibrinolysis in hypertension.

Coagulation and fibrinolysis after moderate and very heavy exercise in healthy male subjects.

To examine the relationship between exercise intensity and activation of coagulation and fibrinolysis, we measured markers of thrombin, fibrin, and plasmin formation in 12 male subjects (mean 24+/-4 yr (SD)) before and after running on a treadmill for 1 h at two different intensities corresponding to moderate (82% maximal heart rate (HR), 68% VO2max) and very heavy (94% maximal HR, 83% VO2max) exercise. During moderate exercise plasma levels of tissue plasminogen activator (t-PA) antigen rose from 3.7+/-0.5 (mean+/-SE) to 14.6+/-1.8 ng x mL[-1] (P < 0.01) and of plasmin-alpha-antiplasmin (PAP) complexes from 2.1+/-0.3 to 4.2+/-0.7 nmol x L[-1] (P < 0.01), whereas prothrombin fragment 1+2 (PTF1+2), thrombin-antithrombin III (TAT) complexes and fibrinopeptide A (FPA) did not change significantly. In response to very heavy exercise, mean plasma levels of t-PA antigen and PAP complexes exceeded the upper limit of normal values 2.5- (P < 0.01) and two-fold (P < 0.01), respectively, while significant increases of plasma levels of PTF1+2 (P < 0.01), TAT (P < 0.05), and FPA (P < 0.01) occurred within the range of normal. We conclude that in healthy young individuals, exercise-induced activation of coagulation is well balanced by activation of the fibrinolytic system, since moderate exercise results in increased plasmin formation only, while at very heavy exercise generation of plasmin seems to exceed that of thrombin and fibrin.

Relationship of blood coagulation and fibrinolysis to vital exhaustion.

Acute physical and psychological stressors affect blood coagulation and fibrinolysis, but little is known about hemostatic factors associated with chronic psychological stress. Prolonged psychological stress may end in a state of vital exhaustion, which has been shown to be a risk factor for first myocardial infarction and recurrent events after coronary angioplasty. The present study tested the hypothesis that vital exhaustion resulting from chronic psychological stress is associated with impaired fibrinolytic capacity and increased coagulation factors. On the basis of a validated questionnaire and subsequent structured interview, a well-defined group of otherwise healthy exhausted men was recruited (N = 15) and compared with age-matched not-exhausted controls (N = 15). Fibrinolytic measures included tissue plasminogen activator (TPA) antigen and plasminogen activator inhibitor (PAI-1) activity, and as coagulation factors we examined factors VIIc, factor VIIIc, and fibrinogen. Control variables were: blood pressure, smoking status, triglycerides, cholesterol, and standard hematological measures. Samples were collected twice to correct for intraindividual fluctuations. Statistical analyses were performed using 2 x 2 mixed model analysis of variance with subsequent univariate testing. Vital exhaustion was associated with significantly elevated levels of PAI-1 activity (p = .023). The higher PAI-1 activity in exhausted subjects (median = 13.0 U/ml vs. 6.0 U/ml) was not accounted for by smoking status or serum lipids. No significant differences were observed in TPA antigen, factor VIIc, factor VIIIc, and fibrinogen. The groups did not differ in blood pressure, smoking status, triglycerides, cholesterol, or standard hematological measures. These data suggest a reduced fibrinolytic capacity in exhausted individuals. Therefore, the relationship between vital exhaustion and risk of myocardial infarction may be mediated in part by an imbalance between blood coagulation and fibrinolysis.

Relationship between endothelial function and fibrinolysis in early hypertension.

Abnormalities in fibrinolysis, endothelial function, and glucose and lipid metabolism have been reported in hypertension. This study was conducted to examine the interrelationships between fibrinolytic factors, glucose and lipid metabolism, and endothelial function in hypertension. The effects of administering an angiotensin converting enzyme inhibitor, benazepril, were also examined. Blood levels of the following substances were measured in patients with borderline and mild hypertension (n=50, 51+/-19 years) and in age-matched controls (n=10): total cholesterol, triglycerides, tissue plasminogen activator activity and antigen, and plasminogen activator inhibitor type 1 activity and antigen. Insulin sensitivity was assessed by oral glucose tolerance test, and endothelial function was assessed by evaluating changes in diameter of the brachial artery during reactive hyperemia as observed by ultrasonography. Activities of tissue plasminogen activator and plasminogen activator inhibitor type 1 were both elevated in the hypertensive patients. Stepwise multiple regression analysis showed that plasminogen activator inhibitor type 1 antigen correlated with insulin sensitivity, total cholesterol levels, and triglycerides levels (P<.01). Endothelial function was negatively correlated with tissue plasminogen activator activity and antigen (P<.01). The chronic administration of benazepril (5-10 mg/d) for 20 weeks improved insulin sensitivity, endothelial function (6.6+/-3.4-->9.0+/-2.5%, P<.01), and tissue plasminogen activator activity and antigen. These results indicate that abnormalities in fibrinolysis are associated with endothelial dysfunction as well as disorders of glucose and lipid metabolism in patients with borderline and mild hypertension. The treatment of such patients with benazepril appeared to improve the impairment in fibrinolysis and endothelial dysfunction.

Cardiovascular risk factors in non-insulin-dependent diabetics compared to non-diabetic controls: a population-based survey among Asians in Singapore

Cardiovascular risk factors were compared between 126 people with non-insulin-dependent diabetes mellitus (NIDDM) and 530 non-diabetics (controls), in a random sample of people (Chinese, Malays, and Asian Indians) aged 40–69 years from the general population of Singapore. Data were adjusted for age and ethnicity. For both genders, people with NIDDM had higher mean body mass indices, waist-hip ratios and abdominal diameters. They also had a higher prevalence of hypertension, higher mean levels of fasting serum triglyceride, slightly lower mean levels of serum high-density-lipoprotein cholesterol, and higher mean levels of plasma plasminogen activator inhibitor-1 and tissue plasminogen activator (antigen). These factors are components of syndrome X (metabolic syndrome) and increase the risk of atherosclerosis and thrombosis. In contrast, there were no important differences for cigarette smoking, serum total and low-density-lipoprotein cholesterol, serum apolipoproteins A1 and B, plasma factor VIIc and plasma prothrombin fragment 1+2. Females with NIDDM, but not males, had a higher mean serum fibrinogen level than non-diabetics, which could explain why NIDDM has a greater cardiovascular effect in females than males. Serum lipoprotein(a) concentrations were lower in people with NIDDM. Mean levels of serum ferritin, a pro-oxidant, were higher in people with NIDDM than controls, but there were no important differences for plasma vitamins A, C and E, and serum selenium, which are anti-oxidants.

Effect of a Change in the Sleep/Wake Cycle on the Diurnal Variation of Fibrinolytic Parameters.

The mechanism underlying the circadian rhythm of fibrinolysis is not well understood. To evaluate the influences of wakefulness and of the intrinsic circadian rhythm on fibrinolytic activity, we examined diurnal changes (8:00 am vs. 8:00 pm) in plasminogen activator inhibitor-1 (PAI-1) activity, tissue plasminogen activator (t-PA) antigen levels, and t-PA activity, as well as in plasma serum cortisol levels, in 10 healthy males (21 +/- 2 years) for two consecutive days. On the first day, subjects remained awake all day and night. They slept during the daytime (8:30 am to 5:30 pm) on the following day. PAI-1 activity and cortisol levels were significantly decreased, and t-PA activity tended to increase during the daytime on the first day. On the morning following overnight wakefulness, PAI-1 activity and cortisol levels did not return to the levels of the previous morning. On the second day, the afternoon decrease in PAI-1 activity, but not cortisol levels, was still observed, although its magnitude was substantially attenuated. No significant diurnal changes were observed in the levels of t-PA antigen throughout the study period. These findings suggest that the diurnal variation of fibrinolytic activity may be governed by an intrinsic circadian rhythm of PAI-1, which can be modified by a change in the time of wakefulness.

Profibrinolytic properties characterize a stably transformed human endothelial cell line.

A stable immortalized venous endothelial cell (IVEC) line, obtained by transfection of human umbilical vein endothelial cells (HUVEC), retains many normal differentiated endothelial characteristics. We compared the fibrinolytic activities of IVEC and HUVEC, and observed that IVEC express a more profibrinolytic phenotype than HUVEC, since they bind and activate plasminogen more efficiently, produce more tissue plasminogen activator and urokinase-type plasminogen activator antigens, and secrete less plasminogen activator inhibitor-1 antigen both under basal conditions and after stimulation with lipopolysaccharide, phorbol ester and tumor necrosis factor. Moreover, immunostaining and Western blotting of IVEC for the plasminogen/tissue plasminogen activator receptor annexin II, as well as Northern blotting of annexin II mRNA, revealed similar patterns of surface expression in IVEC and HUVEC. Plasminogen activator inhibitor-2 is expressed similarly in both cell types. IVEC may be a useful human model for functional and pharmacological explorations and modulations of fibrinolytic system components.

Tissue plasminogen activator (tPA) antigen in plasma: correlation with different tPA/inhibitor complexes

In many studies, tPA antigen has been a strong predictor of myocardial infarction. However, only a few percent of the total tPA antigen present in plasma samples taken at rest constitutes active tPA. The rest is enzymatically inactive and consists of a heterogeneous mixture of tPA in complex with inhibitors such as PAI-1, antiplasmin and C1 inhibitor. In the present study we developed specific two-site ELISA methods for determining the individual protease/inhibitor complexes constituting tPA antigen. We subsequently measured the concentrations of the different complexes in plasma samples taken from 30 healthy individuals. The results show that the concentration of the complex between tPA and PAI-1 in plasma correlated strongly with that of tPA antigen in plasma, as measured with a commercially available kit. Also the correlation between tPA/PAI-1 complex levels in plasma and the PAI-1 activity concentration was significant. However, no significant correlations were found between tPA antigen concentration and tPA/C1 inhibitor or tPA/antiplasmin concentrations in plasma.

Phosphorothioate Oligodeoxynucleotide Inhibition of Restenosis.

Antisense therapy with phosphorothioate oligodeoxynucleotides (PS oligos) has emerged as a potentially useful strategy for inhibiting angioplasty restenosis. Several groups have reported that PS oligos inhibit in vitro vascular smooth muscle cell (SMC) proliferation as well as in vivo neointimal formation after rat carotid artery balloon injury. More recent studies have revealed the presence of a PS oligo G-quartet inhibitory effect, reflecting binding of oligonucleotides to cellular proteins, which is distinct from a hybridization-dependent antisense effect. Studies with the 28-mer phosphorothioate cytidine homopolymer S-dC28 have demonstrated the presence of a non-G-quartet, non-sequence-specific inhibitory effect on SMC proliferation and migration in vitro and neointimal hyperplasia after rat carotid balloon injury in vivo. These effects are the result, in part, of the avid binding of the polyanion PS oligos to heparin-binding growth factors, such as platelet-derived growth factor (PDGF) and basic fibroblast growth factor. Moreover, S-dC28 attenuates PDGF-induced SMC tissue plasminogen activator antigen levels without affecting SMC plasminogen activator inhibitor-1 levels, thereby suggesting a PS oligo net antifibrinolytic effect that would impede SMC migration. Therefore, the further development of these drugs to inhibit angioplasty restenosis must consider the hybridization-specific antisense effects, the non-G-quartet inhibitory effects, and the non-G-quartet, non-sequence-specific inhibitory effects of the pleiotropic PS oligos.

Evaluation of Clotting and Fibrinolytic Activation after Protracted Physical Exercise

The behavior of hemostatic system activation during protracted physical exercise is well known, but the duration of its modification is not yet defined. In order to evaluate the time of hemostatic system activation after prolonged strenuous endurance physical exercise (typical marathon race: 42.195 km, v=15.35 km/h; mean length of time run 2.45± 0.15 hours) 12 well-trained long-distance male runners (mean age: 35±7, range 25–47 years) were investigated. Blood samples were drawn in the morning on the day before the performance, immediately after the race, and 24 hours and 48 hours after the end of run. With respect of baseline, immediately after the race, a significant decrease of fibrinogen (−25%) and significant increases of prothrombin fragment 1+2 (+633%) and thrombin-antithrombin complex (+848%) were observed. A significant acceleration of euglobulin lysis time (−41%), and rises of plasma levels of tissue plasminogen activator antigen (+361%), plasminogen activator inhibitor type 1 antigen (+235%), d-dimer (+215%), and plasma fibrinogen degradation products (+1200%) were also found. Only a slight, yet not significant, decrease in plasminogen activator inhibitor type 1 activity was observed. One day after the end of marathon different parameters were still unchanged. Forty-eight hours after the competition all parameters investigated returned to baseline values. These results indicate a persistence of clotting as well as fibrinolysis activation up to 24 hours after the end of the race.

Hemostatic factors as predictors of ischemic heart disease and stroke in the Edinburgh Artery Study.

Plasma fibrinogen is a consistent predictor of ischemic heart disease (IHD) in prospective studies, but there are fewer data relating other hemostatic variables to IHD and also to stroke. We therefore studied the relationships of plasma fibrinogen, von Willebrand factor antigen, tissue plasminogen activator (TPA) antigen, factor VII, and fibrin D-dimer to incidence of IHD and stroke and determined whether any associations could be explained by conventional risk factors and baseline heart disease. In the Edinburgh Artery study, 1592 men and women aged 55 to 74 years, randomly sampled from the general population, were followed prospectively over 5 years to detect fatal and nonfatal IHD and stroke events. During the 5 years, 268 new vascular events were identified. Baseline plasma fibrinogen was independently related to risk of stroke in multivariate analysis that adjusted for cigarette smoking, LDL-cholesterol, systolic blood pressure, and preexisting IHD (relative risk [RR] 1.52, 95% confidence interval [CI] 1.17, 1.98). TPA antigen, and fibrin D-dimer were also independently associated with risk of stroke (RR 1.69,95% CI 1.22,2.35 and RR 1.96, 95% CI 1.12,3.41, respectively). Significant relationships were found between TPA antigen and myocardial infarction (P < or = .05). In older men and women, increased coagulation activity and disturbed fibrinolysis are predictors of future vascular events (both IHD and stroke).

Lower androgenicity is associated with higher plasma levels of prothrombotic factors irrespective of age, obesity, body fat distribution, and related metabolic parameters in men

The purpose of this study was to examine the relationships between androgenic status and plasma levels of both prothrombotic and antithorombotic factors in men, irrespective of obesity, body fat distribution, and metabolic parameters. Sixty-four apparently healthy men, 40 with a body mass index (BMI) greater than 25 kg/m 2 (overweight and obese [OO]) and 24 non-obese controls with a BMI less than 25, were selected and evaluated for (1) plasma concentrations of plasminogen activator inhibitor-1 (PAI-1) antigen, PAI-1 activity, fibrinogen, von Willebrand factor (vWF) antigen, vWF activity, and factor VII (FVII) as the prothrombotic factors; (2) plasma levels of tissue plasminogen activator (TPA) antigen, protein C, and antithrombin III as the antithrombotic factors; (3) fasting plasma concentrations of insulin and glucose and the lipid pattern (triglycerides [TG] and total and high-density lipoprotein [HDL] cholesterol) as the metabolic parameters; and (4) free testosterone (FT), dehydroepiandrosterone sulfate (DHEAS), and sex hormone—biding globulin (SHBG) serun levels as the parameters of androgenicity. Body fat distribution was evaluated by the waist to hip ratio (WHR). In OO and non-obese subjects taken together, plasma levels of PAI-1 antigen, fibrinogen, and FVII were inversely associated with FT ( r = .255, P < 0.5, r = −3.14, P < .05, and r = −.278, P < .05, respectively), and the negative relationships of both fibrinogen and FVII with FT were maintained after stepwise multiple regression analysis. Plasma concentrations of PAI-1 antigen and PAI-1 activity were also negatively correlated with SHBG ( r = −.315, P < .05 and r = −.362, P < 0.01, respectively), and these associations held irrespective of the other parameters investigated. None of the antithrombotic and fibrinolytic factors were independently related to serum androgen levels. Subjects with a BMI higher than 25 kg/m 2 had higher plasma concentrations of PAI-1 antigen, PAI-1 activity, and fibrinogen as compared with non-obese controls ( P < .001, P < .001, and P < .01, respectively). In addition, in OO and control subjects as a whole, multiple stepwise regression analysis showed that the associations of BMI with PAI-1 activity, fibrinogen, vWF antigen, and vWF activity were independent of any other metabolic and hormonal parameters. Plasma concentrations of PAI-1 antigen, PAI-1 activity, and fibrinogen were also directly correlated with WHR in all subjects taken together, irrespective of the other parameters investigated. Evaluation of antithrombotic factors showed that OO subjects had higher TPA plasma concentrations than non-obese controls ( P < .001), whereas protein C and antithrombin III did not differ in the two groups. TPA was also directly correlated with BMI ( r = .415, P < .001) and WHR ( r = .393, P < .001) in all subjects. The results of this study indicate that (1) men with lower FT serum levels have higher fibrinogen and FVII plasma concentrations, and those with lower SHBG serum levels also have higher levels of PAI-1 antigen and activity; (2) irrespective of other factors, obesity per se may account for higher concentrations of PAI-1, fibrinogen, and vWF; (3) plasma levels of PAI-1 (antigen and activity) and fibrinogen correlate independently with WHR; and (4) among the investigated antithrombotic factors (TPA antigen, protein C, antithrombin III), only TPA antigen plasma concentrations are higher in men with abdominal obesity. Thus, because of the increase in several prothrombotic factors, men with central obesity, particularly those with lower androgenicity, seem to be at greater risk for coronary heart disease (CHD). Apparently, this risk is not counteracted by a parallel increase in plasma concentrations of antithrombotic factors.

Indicators of fibrinolysis during cardiopulmonary bypass after exogenous antithrombin-III administration for acquired antithrombin III deficiency

elapsed time for the heparin boluses and ACT testing was 30 minutes. A presumptive diagnosis of AT-III deficiency was made, and 2,500 U of pooled AT III was administered. The dose was based on the assumption that the patient's circulating AT-III activity was decreased by approximately 50%, and that adding 2,500 U of AT llI to his circulating volume would bring AT-III activity back to 100%. The ACT rose to 635 seconds, and cardiopulmonary bypass (CPB) was immediately initiated. CPB lasted 59 minutes, and no further heparin was required. After CPB, protamine sulfate, 200 rag, was administered IV, and the resulting ACT was 119 seconds. Postoperatively, the thromboelastogram was normal. The patient received 450 mL of autologous blood that had been withdrawn at the start of the case for the purpose of euvolemic hemodilution, and he received no other blood products. His postoperative course was uneventful, and he was discharged on the 5th postoperative day. When it was determined during the case that the patient was heparin resistant, blood samples were withdrawn from his autologous blood unit for baseline studies. This unit had been stored at 34°C for 30 minutes before sampling. Additional samples were drawn from the patient after the second and third boluses of heparin, after AT-Ill administration just before initiation of CPB, 30 minutes after initiation of CPB, and after administration of protamine at the end of CPB. The patient's temperature, as recorded by simultaneous esophageal/urinary temperature probes, was 35.5°/35.9°C, 35.1/35.7°C, 36.2/ 35.6°C, 36.1/37°C, and 36.1/36.8°C, respectively. Blood samples, including the sample withdrawn from the autologous unit, were placed on ice for transport to the clinical laboratory. Blood was anticoagulated by addition of 4.5 mL of whole blood to 0.5 mL of 130 mmol/L sodium citrate. All samples were centrifuged for 10 minutes at 2,500g at room temperature. Citrated plasma was frozen at -80°C. The patient's permission was obtained to run the blood samples for determination of F1 + 2, plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator antigen (TPA Ag), and AT III activity levels. RESULTS

Increased thrombin generation and complement activation in patients with type IIA hyperlipoproteinemia: effects of simvastatin treatment

The aim of this study was to demonstrate the existence of increased thrombin generation and complement activation in patients with type IIa primary hyperlipoproteinemia, but no signs of atherosclerotic vascular disease and to assess the effects of simvastatin treatment in these patients. We studied 40 patients with type IIa primary hyperlipoproteinemia and 40 healthy subjects matched for sex, age, body mass index, and smoking status. The study was divided into two phases. In the first phase, a cross-sectional comparison of lipid and hemostatic patterns was performed between patients and controls. In the second phase, we assessed the effect of a persistent reduction in cholesterol synthesis induced by simvastatin in patients with hypercholesterolemia. The lipid pattern in patients with hypercholesterolemia was consistent with the characteristic features of this form of hyperlipoproteinemia. Moreover, factor VII, fibrinogen, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin III complexes (TAT), fibronectin, and the c fraction of the third component of the complement system (C3c) levels were significantly higher, and antithrombin III was significantly lower in patients than in controls. Regarding the fibrinolytic pattern, in patients there were no significant differences in tissue plasminogen activator antigen before and after venous occlusion (VO), plasminogen activator inhibitor type 1 activity before and after VO, plasminogen, and alpha 2-antiplasmin plasma levels compared with control subjects. Factor VII, fibrinogen, F1+2, TAT, fibronectin, and C3c were significantly correlated with total and low-density lipoprotein (LDL) cholesterol levels, whereas no significant correlation with high-density lipoprotein (HDL) cholesterol and triglyceride levels was found. In addition to the well-established lipid-lowering effect, simvastatin (20 mg/d for 8 weeks) significantly reduced factor VII, fibrinogen, F1+2, TAT, fibronectin, and C3c levels in patients with hypercholesterolemia, but the observed reductions were not significantly correlated with total and LDL cholesterol levels. Our results show that type IIa hyperlipoproteinemia is characterized by increased in vivo thrombin generation and complement activation with no abnormalities of fibrinolysis. This thrombophilic state, which is associated with a high incidence of atherosclerosis and thrombotic complications, can be decreased with simvastatin via cholesterol lowering, but the relationship between these events remains to be investigated.

Investigation of haemostatic parameters in relation to outcome in an intensive care population

A pilot study to identify the relation of haemostatic factors to patient outcome in the intensive care population. After ethics committee approval 50 admissions to the ICU were recruited consecutively subject to a maximum of two patients studied at any one time. After completing investigations in one patient the next admission was recruited. On the first day of admission a peripheral blood sample was taken and sent for the following tests: full blood count, prothrombin time (PT), activated partial thromboplastin time (aPTT) and thrombin time (TT), plasma viscosity, fibrinogen, factor VII, factor VIII, von Willebrand factor antigen, tissue plasminogen activator antigen, plasminogen activator inhibitor activity, fibrinogen degradation products and thrombelastography (TEG) - where the reaction time R, clot formation time K, maximum amplitude MA and angle alpha were measured. APACHE II scoring, length of hospital and ICU stay and death in hospital were also recorded. Survival or death was used as the primary outcome measure. The differences in the above tests in the survivors and non-survivors were analysed using Mann-Whitney tests, and P<0.05 was taken to indicate significance. Thirty patients survived and 20 patients died. There was a significant difference in the APACHE II (P=0.003), length of hospital stay (P=0.01), von Willebrand factor (P=0.003) and tissue plasminogen activator antigen activity (P=0.05) in the survivors and non-survivors. There was no significant difference in any of the other parameters. Von Willebrand factor and tissue plasminogen activator antigen levels are significantly higher in the non-survivors of an intensive care population. They probably reflect diffuse, endothelial disturbance, may be useful prognostic indices of severity of illness and merit further evaluation.

Gemfibrozil treatment of hypertriglyceridemia: Improvement on fibrinolysis without change of insulin resistance

The fibrinolytic and metabolic changes associated with gemfibrozil treatment of hypertriglyceridemia were evaluated in 16 patients with type IV hyperlipidemia by criteria of triglyceride levels >250 mg/dl and total cholesterol levels <220 mg/dl. The plasma triglyceride level was significantly lower (323 ± 71 vs 189 ± 57 mg/dl; p = 0.000) and high-density lipoprotein cholesterol level significantly higher (33.5 ± 4.6 vs 38.0 ± 6.7 mg/dl; p = 0.005) after 3 to 4 months of gemfibrozil treatment. However, the glucose and insulin metabolism measured by oral glucose challenge and insulin suppression tests showed no significant changes after gemfibrozil therapy. In contrast, plasma plasminogen activator inhibitor-1 antigen (36.9 ± 12.4 vs 27.3 ± 11.4 ng/ml; p = 0.008) and activity (15.5 ± 5.5 vs 11.8 ± 3.0 IU/ml; p = 0.009) and tissue plasminogen activator antigen (13.2 ± 4.0 vs 10.4 ± 3.7 ng/ml; p = 0.007) were significantly depressed, and tissue plasimogen activator activity (0.57 ± 0.31 vs 0.69 ± 0.38 IU/ml; p = 0.015) was significantly elevated by gemfibrozil. The data indicate that lowering plasma triglyceride and raising high-density lipoprotein cholesterol levels by gemfibrozil treatment also improved the fibrinolytic system without changes of insulin resistance and glucose intolerance in patients with isolated hypertriglyceridemia. (Am Heart J 1997;134:565-71.)

9 Haemostatic changes and the oral contraceptive pill

Oral contraceptives have been linked to an increased incidence of thrombovascular disease. This may be mediated by their effects on the haemostatic system. An increase in the activity of coagulation Factors VII, X and fibrinogen occur with pill usage. Increased Factor VII levels are dependent on both the oestrogen and progestogen component of the oral contraceptive. A reduction in antithrombin III levels has also been observed in some but not all studies. Increased fibrinolysis has also been shown in oral contraceptive users which should balance the changes in the coagulation pathway. The increase in fibrinolytic potential is thought to be due to a decrease in the levels of plasminogen activator inhibitor I combined with an increase in the levels of plasminogen; tissue plasminogen activator antigen is decreased in most studies. The increased levels of endpoints of coagulation and fibrinolysis in pill users indicate that enhanced activity of both systems is occurring in vivo. The increased coagulation activity appears to be balanced by the rise in fibrinolytic activity, so preserving haemostatic balance. Enhanced platelet activity has also been shown in women taking oral contraceptives. Thrombus formation can result, however, when local vascular wall damage exists, or when other risk factors for thrombo-embolism, such as older age and smoking, coexist and create a local activation resulting in a thrombus. In these situations, the small differences in levels of coagulation factors in women taking different oral contraceptive formulations may be important. Pills containing the lowest doses of oestrogen (20 micrograms ethinyloestradiol) have shown the least changes in haemostatic factors. The progestogen component of the pill modifies the effect of oestrogen on the haemostatic system.

THE EFFECT OF PHYSICAL CONDITIONING SUGGESTS ADAPTATION IN PROCOAGULANT AND FIBRINOLYTIC POTENTIAL

Acute exercise evokes a transient increase in procoagulant activity. We evaluated the effect of physical conditioning on the activation of the coagulation and fibrinolytic systems. Two groups of subjects of different aerobic endurance levels (athletes and controls with maximal oxygen uptake ( VO 2 max ) 68,4 and 52,6 ml·kg −1·min −1, respectively), were tested at rest and after standardized exercise at 80 % of their individual VO 2 max . There was a significant increase in prothrombinfragment 1+2 (F1+2) level among controls in response to standardized exercise (p<0.05), whereas no significant difference in the level of F1+2 between athletes and controls at rest or in response to exercise was demonstrated. Tissue plasminogen activator (tPA) antigen level at rest was significantly lower in athletes compared to controls (p<0.03). A significant increase was found in the tPA level after standardized exercise in both groups (p<0.02), which was lower in athletes compared to controls (p<0.05). There were no significant differences between athletes and controls in plasminogen activator inhibitor-1 (PAI-1) and thrombin antithrombin complex (TAT) levels at rest. Athletes had a significantly lower PAI-1 level than controls after exercise (p<0.05). In conclusion, the present study suggests an increased activation of the coagulation system in response to exercise in controls only. It also suggests adaptive changes in fibrinolytic potential induced by physical conditioning, as demonstrated by the lower level of tPA at rest and the lower levels of tPA and PAI-1 after exercise in athletes compared to controls. © 1997 Elsevier Science Ltd

Clearance of tissue plasminogen activator (TPA) and TPA/plasminogen activator inhibitor type 1 (PAI-1) complex: relationship to elevated TPA antigen in patients with high PAI-1 activity levels.

To evaluate the effect of plasminogen activator inhibitor type 1 (PAI-1) levels on the clearance of total tissue plasminogen activator (TPA) antigen, we studied the clearance of active TPA and TPA/PAI-1 complex in subjects with low (181+/-109 pmol/L; n=7) and high (1166+/-322 pmol/L; n=4) baseline active PAI-1. A 5-microg/kg bolus of TPA was infused over a 15-second period followed by measurement of TPA activity, TPA antigen, TPA/PAI-1, TPA/C1 inhibitor, PAI-1 activity, and PAI-1 antigen over a 4-hour period. alpha-Phase clearance of total TPA antigen was faster in subjects with low PAI-1 (t(1/2) of 3.5+/-0.7 minutes) versus high PAI-1 (t(1/2) of 5.3+/-0.9 minutes) (P=.006). Clearance of all factors was best fit by a two-compartment pharmacokinetic model based on a computer-simulated human circulatory system. The average hepatic clearance fraction in the two-compartment model was greater for active TPA (89+/-10%, t(1/2) of 2.4+/-0.3 minutes) than for TPA/PAI-1 complex (48+/-17%, t(1/2) of 5.0+/-1.8 minutes) (P=.0006). Plasma clearance of active TPA was faster than clearance of TPA/PAI-1 complex. High levels of active PAI-1 converted more TPA into TPA/PAI-1 complex, effectively slowing the clearance of total TPA antigen and explaining in part why high levels of PAI-1 activity are associated with increases in total TPA antigen.