Correlation of circulating 17beta-oestradiol with haemostatic factors in healthy postmenopausal women.

The aim of the study was to evaluate any correlation between the circulating oestrogenic hormone 17beta-oestradiol and haemostatic factors in healthy postmenopausal women. In keeping with this objective, the correlations were evaluated irrespective of whether the source of the hormone was purely endogenous or exogenous as well. Accordingly, a univariate correlation adjusted for age, body mass index, and duration of menopause was determined in 42 healthy postmenopausal women aged 47-78 years, 19 of whom were self-reported users of hormone replacement therapy. The rest were self- reported never users. Serum 17beta-oestradiol exhibited a direct correlation with endogenous thrombin potential extrinsic pathway (R = 0.42, p = 0.01) and prothrombin fragments 1 and 2 (R = 0.37, p = 0.03) and an inverse correlation with antithrombin III (R = -0.36, p = 0.03) and alpha(2)-antiplasmin (R = -0.45, p = 0.005). The observations suggest an association of this hormone with net thrombin generation on the one hand and improved fibrinolysis on the other.

Triglyceride dependence of factor VII coagulant activity in deep venous thrombosis.

The effect of incubation of plasma with lipoprotein lipase on factor VII coagulant (FVII:C) activity was examined in 40 patients, 22 male and 18 female, aged 28 to 77 years, with history of venographically proven deep venous thrombosis (DVT). While the mean (+/-SEM) FVII:C activity of the 40 patients was 100.9 +/- 4.1%, 19 patients had FVII:C activity less than 100%, 11 had 100 to 120% activity and 10 patients had greater than 120% FVII:C activity. The mean triglyceride level of all the patients was 84.0 +/- 6.5 mg/dl. The FVII:C activity correlated significantly with triglyceride (r = 0.36; n = 40; p = 0.021). There was about 30% average loss of FVII:C activity upon incubation of plasma with lipoprotein lipase. The mean activity loss increased from 23.8% to 31.5% and 42.6% in patients whose FVII:C activity levels were less than 100%, between 100 and 120% and more than 120% respectively, the variation in the means being statistically significant (p < 0.001). While according to current opinion, FVII:C activity represents the total FVII mass (FVII plus FVIIa) and activity state, the present findings demonstrate a lipid dependence of FVII:C activity, and raises the possibility of a therapeutic option of controlling FVII:C by controlling triglyceride levels.

Interference of an activity assay of tissue-type plasminogen activator in human plasma by endogenous factors.

The estimation of the activity of circulating tissue-type plasminogen activator (t-PA) using the Coaset t-PA or Spectrolyse/fibrin t-PA reagent kits involves incubation of plasma with excess plasminogen in the presence of human fibrin fragments, and detection of the plasmin generated by an end-point amidolytic assay. We examined the interference of endogenous inhibitors such as plasminogen activator inhibitor-1 (PAI-1) and alpha 2-antiplasmin, and that of an endogenous activator namely single-chain urokinase-type plasminogen activator (scu-PA) on the Coaset t-PA assay. An extra acidification of the samples already collected into an acidified anticoagulant raised the mean Coaset t-PA activity of 15 samples from 1.39 +/- 0.25 (mean +/- SEM) to 1.71 +/- 0.27 (P < 0.001). In twelve of these samples, the PAI-1 and alpha 2-antiplasmin activities were determined. The increase in the t-PA activity by acidification was found to correlate inversely with PAI-1 (r = -0.66; n = 12; P = 0.019) but not with alpha 2-antiplasmin, demonstrating that the extra acidification step released t-PA from the t-PA-PAI-1 complex, but had no influence on the endogenous alpha 2-antiplasmin in the assay system. Incubation with monoclonal antibody against alpha 2-antiplasmin increased the Coaset t-PA activity in a concentration-dependent manner, linearly up to 2 micrograms/ml (final) of the antibody, irrespective of the extra acidification, the maximal rise being 41.5% and 19.7% in an in-house and commercial plasma pools respectively. In contrast to alpha 2-antiplasmin antibody, monoclonal antibody against scu-PA decreased the Coaset t-PA activity in the in-house and commercial plasma pools again in a concentration-related manner demonstrating that scu-PA in addition to t-PA was being measured by this method. Incubation with an irrelevant antibody (anti-DNA monoclonal antibody) did not affect the Coaset t-PA values. The mean Coaset t-PA activity of 40 subjects decreased from 1.76 +/- 0.10 (mean +/- SEM) to 0.73 +/- 0.07 when incubated with 8 micrograms/ml (final) monoclonal antibody against scu-PA (P < 0.001). The 't-PA' activity in the absence of scu-PA antibody correlated with the u-PA antigen (r = 0.53; n = 40; P < 0.001), and the activity in the presence of scu-PA antibody correlated with the t-PA activity measured by the bio-functional immunosorbent assay (r = 0.86; n = 40; P < 0.001). Hence, unless the Coaset t-PA activity is measured with appropriate amounts of antibodies to alpha 2-antiplasmin and scu-PA, it is best to qualify the activity measured by this method as being that of total plasminogen activators.