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

Laboratory evaluation of a new integrative assay to phenotype plasma fibrinolytic system

BACKGROUND

There is currently no universal and standardized test available to phenotype plasma fibrinolytic system.

AIMS

Our main aims were to evaluate the performances of the 'global fibrinolysis capacity' assay (GFC) performed with the Lysis Timer® instrument, and to study the influence of some preanalytical conditions.

METHOD

Euglobulin clot lysis time (ECLT) and GFC were performed under several preanalytical conditions.

RESULTS

GFC showed satisfactory intra- and inter-run precision. Frozen controls and reagents showed stability over the studied period. There was no statistically significant difference between GFC assessed in plasma samples processed at 4 °C or at 20 °C. GFC assessed with frozen-thawed plasma samples was prolonged when compared to fresh samples (p = 0.014). The centrifugation scheme had no influence on PAI-1 activity levels, GFC and ECLT. Reference interval for GFC ranges from 29.3 (C I90% = 26.9-31.9) to 49.5 (90% CI = 45.9-52.2) minutes. In addition, a preliminary study in 40 healthy volunteers and 43 adult patients referred for investigation of a bleeding disorder was conducted to compare GFC and ECLT assays in their ability to classify samples with shortened or prolonged clot lysis times. Disagreements between ECLT and GFC were observed for 23 samples (out of 83), most of them minor.

CONCLUSION

GFC is suitable and convenient for a broad clinical use and can be performed with frozen-thawed plasma samples. Unlike ECLT, GFC is designed to take into account the balance between inhibitors and activators of the fibrinolytic system and could detect both hypo- and hyperfibrinolytic states. Whether it is as suitable as or even better than ECLT to detect a bleeding tendency due to a hyperactive fibrinolytic system deserves to be properly investigated.

Blood coagulation and metabolic profiles in middle-aged male and female ob/ob mice

Obese and diabetic states in humans are associated with an increased incidence of thrombotic diseases caused by various coagulation abnormalities. Genetically obese ob/ob mice produce metabolic abnormalities similar to those associated with type 2 diabetes. However, little is known about their coagulation features or sex differences. The present study aimed to determine the effects of obese and diabetic complications on blood coagulation and vascular diseases by exploring correlations between blood coagulation and metabolic profiles in middle-aged male and female ob/ob mice. Plasma levels of plasminogen activator inhibitor 1 (PAI-1) were significantly increased, whereas those that of platelet factor-4 (PF-4) was slightly, but significantly increased in male and female ob/ob mice compared with lean counterparts. Prothrombin time (PT) was significantly shortened in female ob/ob mice and activated partial thrombin time (APTT) significantly differed between male and female ob/ob mice. Plasma levels of antithrombin (AT) were significantly increased in male and female ob/ob mice. None of the other coagulation and fibrinolytic factors examined significantly differed between ob/ob mice and lean counterparts. On the contrary, factors such as body weight and cholesterol levels significantly differed between ob/ob and lean mice, whereas glucose, fructosamine and insulin levels significantly differed only in one sex of each strain. These results provided fundamental information about blood coagulation and metabolic features for exploring the function of altered blood coagulation states in ob/ob mice.

No influence of proinsulin and insulin on plasma levels of plasminogen activator inhibitor type 1 and tissue plasminogen activator in young women before and during intake of contraceptive steroids

Clinical observations in patients predisposed to cardiovascular disorders and recent experimental observations suggest that proinsulin and insulin participate in the regulation of fibrinolysis in vivo. In the present study, we examined if proinsulin and insulin affect the constitutive (fasting) secretion of plasminogen activator inhibitor type 1 (PAI-1) and tissue plasminogen activator (t-PA) in young healthy women (N = 17). We also measured the antigen concentrations of PAI-1 and t-PA during slow and fast changes in proinsulin and insulin levels induced by oral (OGTT) and intravenous (IVGTT) glucose tolerance tests. The assessments were performed before and after 6 months of treatment with contraceptive steroids, which have a well-defined influence on the fibrinolytic variables. We observed no consistent correlations between fasting values of proinsulin, insulin, PAI-1, and t-PA either before or during hormonal treatment. Before hormonal treatment, PAI-1 and t-PA antigen levels decreased (P < .05) during the hyperproinsulinemia and hyperinsulinemia induced by the OGTT and IVGTT. After hormonal intake for 6 months, a decrease only in t-PA concentrations during the OGTT was observed despite similar proinsulin and insulin responses to the glucose loads. Our findings suggest that proinsulin and insulin have no influence on the regulation of plasma levels of PAI-1 and t-PA in young healthy women, irrespective of intake of contraceptive steroids.

On the action of a heparan-like glycosaminoglycan (Hemovasal) on the mechanism of haemostasis and fibrinolysis

Hemovasal produced by Manetti-Roberts, Florence, Italy, is a glycosaminoglycan obtained from porcine intestinal mucosa which belongs to the family of heparan sulfates. The substance was examined On 36 male survivors of myocardial infarction with an interval of at least 6 months after the acute event. No anticoagulants were given and ASA was withdrawn at least 2 weeks before the trial. Hemovasal was administered in 3 different i.m. doses as single injections. A further group received a daily oral dose of 300 mg for one week. A comparable placebo group of patients as well as a group of healthy volunteers was run in parallel. The coagulation profile showed only a slight prolongation of the aPTT, a trace of diminution of Antithrombin III and no activation of Heparin cofactor II. The fibrinolytic system showed an enhancement of the diurnal increase of t-PA without an alteration of the total increase of this activity. There was a considerable and highly significant diminution of the PAI-1 activity. This was dose dependent and could be found after i.m. as well as after oral administration. It was assumed that the thrombolytic effect which was repeatedly described was a consequence of the diminution of PAI-1.

Changes in fibrinolytic parameters in male patients with type 2 (non-insulin-dependent) diabetes mellitus

We examined changes in fibrinolytic parameters in male patients with diabetes mellitus (DM) and controls. DM patients were divided into three groups: patients without retinopathy, patients with simple retinopathy, and patients with proliferative retinopathy. Plasma levels of t-PA (tissue plasminogen activator) and t-PA-PAI-1 (plasminogen activator inhibitor-1) complex increased with increase in age, but those of PAI-1 (total and free) did not change in controls. On the other hand plasma levels of PAI-1 decreased with increase in age in DM patients. Plasma levels of t-PA, t-PA-PAI-1 complex, free and total PAI-1 increased with increase in body mass index in controls, but no significant changes were shown in these parameters in DM patients. When compared with controls, plasma levels of t-PA, t-PA-PAI-1 complex and PAI-1 were lower in DM patients. Plasma levels of UK (urokinase) and Lp(a) were higher in DM patients. ELT (euglobulin clot lysis time) was significantly shorter in DM patients than in controls. Patients without retinopathy showed increased fibrinolytic activities compared with those with retinopathy due to the increased levels of t-PA in plasma. These results seem to indicate that blood vessels release larger amounts of t-PA at the early stage of DM, then release being impaired at its advance stage. It is also suggested that the regulatory control mechanisms of fibrinolytic activity associated with mechanisms of fibrinolytic activity associated with change in age and body mass index are different between patients with DM and normal people.

Impaired fibrinolytic activity induced by ingestion of butter: effect of increased plasma lipids on the fibrinolytic activity

To investigate the effects of the increased plasma lipid level on fibrinolysis, we measured the levels of fibrinolytic components in serially obtained plasma samples from healthy volunteers after the intake of different amounts of butter. Plasma triglyceride level increased significantly after butter intake compared to the control group. Eight hours after the intake of 100g of butter, plasminogen activator inhibitor 1 (PAI-1) level in plasma was significantly higher and euglobulin clot lysis time was significantly prolonged compared to those of the control group. There was no effect on plasma tissue plasminogen activator level. These results suggest that the temporary increase in plasma triglyceride level induced high PAI-1 level, resulting in impaired fibrinolytic activity. The effect of temporary hyperlipidemia on platelet function was also analyzed and revealed that the response of platelets to ADP and collagen was lower in the butter intake group compared to those of the control.

Circadian fluctuations of tissue plasminogen activator antigen and plasminogen activator inhibitor-1 antigens in vasospastic angina

To elucidate the circadian variation of fibrinolytic components in vasospastic angina, plasma levels of tissue plasminogen activator antigen (t-PA), free plasminogen activator inhibitor antigen (free PAI-1), t-PA/PAI-1 complex, and total PAI-1 were measured in venous plasma samples. Samples were taken every 6 hours (6:00 AM, noon, 6:00 PM, and midnight) for 24 hours in 14 patients with vasospastic angina, in 9 patients with exertional angina, and in 19 normal subjects. Twenty-four-hour Holter monitoring (Holter monitor, Del Mar Avionics, Irvine, Calif.) was also carried out in all subjects. All of the fibrinolytic components showed circadian variation, with a peak level at 6:00 AM in every study group except for the t-PA/PAI-1 complex in the group of patients with exertional angina. The values for all or the fibrinolytic components at each sampling time were higher in patients with coronary artery disease than in normal subjects. In particular, the mean value of free PAI-1 at 6:00 AM in patients with vasospastic angina was significantly higher than that in normal subjects and that in patients with exertional angina. This value of free PAI-1 in patients with vasospastic angina was closely associated with the duration of ischemic attacks. These results suggested that the circadian fluctuation of fibrinolytic components may be an important factor that leads to coronary thrombosis at the time of coronary spasm, especially in the early morning.