Haemostasis最新文献

A mutation of Tyr-->Cys at position 280 of the gamma chain of fibrinogen was recently determined to be the cause for fibrinogen Banks peninsula. A novel polymerase chain reaction/restriction digestion assay for this mutation was developed and used for the screening of 300 apparently healthy European blood donors. None of these subjects carried the mutation.

Activated protein C resistance (APCR) is a common cause of familial thrombophilia and venous thrombosis. The aim of the study was to investigate the prevalence of APCR associated with factor V Leiden mutation and its relevance in comparison to other risk factors for thromboembolic disorders in women with a history of previous complicated pregnancies (history of fetal loss in the second and third trimester n = 34, preeclampsia n = 46). The frequency of APCR was significantly higher in women with a history of fetal loss and preeclampsia (23.5 and 26.1%, respectively) compared with a control group (3.8%). The prevalence of antithrombin, protein C and protein S deficiencies and the presence of antiphospholipid antibodies were also investigated: the prevalence of at least one disorder was 41.2% in the group with previous fetal loss, 37.0% in the group with previous preeclampsia and 7.5% in the control group.

We used thrombin times and a competitive radiometric assay to identify, quantitate and characterize endogenous heparin-like molecules in umbilical cord (n = 58) and normal adult (n = 25) plasma. Thrombin times for cord plasma (29.6+/-3.6 s) were significantly longer (p< or = 0.0005) than those for adult plasma (18. 9+/-2.3 s), suggesting increased endogenous heparins. A radiometric assay based on the displacement of (125)I-heparin from protamine-Sepharose revealed that protease-digested plasma contained heparin/heparan sulfate, and plasma that was not digested with protease appeared not to contain heparin/heparan sulfate. More heparin/heparan sulfate was identified in cord than in adult plasma (p< or =0.05), but heparinase digestion produced significantly (p< or =0.001) reduced concentrations of heparin/heparan sulfate in only 39% of the samples. The lack of heparinase sensitivity in 61% of the protease-digested samples apparently was due to low molecular weight (LMW) heparins, for control heparin fragments of 5 kD that did not extend thrombin times were also less affected by heparinase, but the same LMW heparins were detected by radiometric assay. Despite normal thrombin times in all samples, the amounts of endogenous heparin/heparan sulfate identified in protease-digested samples by radiometric assay were of sufficient concentrations to produce inordinately prolonged thrombin times when compared with the same concentrations of unfractionated heparin. Collectively, these findings suggest the presence of a plasma reservoir of endogenous heparin/heparan sulfates in normal cord and adult plasma. These endogenous heparin/heparan sulfates are bound to plasma proteins, and an as yet undetermined proportion of these bound heparin/heparans are most likely LMW molecules.

We evaluated the plasma concentrations of platelet activation markers and platelet-derived microparticles (PMP) in patients with connective tissue diseases complaining of peripheral circulation disorders (n = 16) and studied the effect of ticlopidine hydrochloride (ticlopidine) on PMP generation. There were significant differences in the levels of PMP and a platelet activation marker between before and after treatment with ticlopidine (PMP: 695 +/- 393 vs. 354 +/- 206/10(4) platelets, p < 0. 01; platelet CD63: 9.13 +/- 5.64 vs. 5.22 +/- 2.74%, p < 0.05). On the other hand, markers of vascular endothelium, such as vascular endothelium-derived small vesicles and serum thrombomodulin levels, were not affected by the administration of ticlopidine. Levels of cytokines and soluble adhesion molecules remained unchanged by ticlopidine administration. These findings suggest that ticlopidine may be useful for the inhibition of PMP-dependent vascular damage in patients with connective tissue diseases complaining of peripheral circulation disorders.

Standard flow cytometers provide relative numbers of activated platelets, microparticles, and platelet aggregates. With fluorescent beads it is now possible to determine absolute numbers. Whole blood and platelet-rich plasma were incubated with agonists (ADP, collagen, thrombin). CD62p expression, microparticle and platelet aggregate formation were measured. Flow-Count Fluorospheres((R)) were added to calculate absolute concentrations. After activation there was an increase in the percentage of CD62p-positive platelets. However, the total number of platelets decreased and therefore the absolute number of CD62p-positive platelets did not increase but decreased. The number of CD62p-positive platelets decreased not as much as the number of CD62p-negative platelets, which explains why the relative percentage of CD62p-positive platelets increased. A similar increase in percent and decrease in absolute counts was found for microparticles. Platelet aggregates increased both in relative and absolute numbers. These results suggest that the detection of activated platelets by flow cytometry has to be complemented by the determination of the absolute concentrations to avoid misinterpretation.

This study examines the evolution of the thrombotic activity in patients with myocardial infarction (MI) treated with aspirin (200 mg/day) for 2 years after MI. Plasma samples of 10 patients were collected at 7, 30, 60, 90, 120, 150, 180, 360 and 720 days. In all the samples we measured fibrinogen (Fg), high molecular weight Fg (HMW-Fg), fibrinopeptide A (FPA), prothrombin fragment 1+2 (F1+2), beta-thromboglobulin (beta-TG), von Willebrand factor (vWF), tissue factor (TF) and TF pathway inhibitor (TFPI). The plasma Fg, HMW-Fg, FPA, F1+2, beta-TG and vWF levels were significantly elevated in the patients at the beginning of the study as compared to the normal group. The 95% confidence intervals were Fg 277-333 mg/dl, HMW-Fg 200-244 mg/dl, FPA 5.3-16.5 ng/ml, F1+2 1.4-1.8 nmol/l, beta-TG 110-118 IU/ml and vWF 139-195%. At thirty days Fg and HMW-Fg returned to normal levels, whereas the increase in FPA and F1+2 levels persisted throughout the study. At 120 and 150 days, respectively, beta-TG and vWF returned to normal levels. The increase in thrombin generation and activity pointed to a persistent hypercoagulable state 2 years after MI. Plasma levels of TF and TFPI showed no statistically significant variations with respect to the normal values over the 2-year period studied. In conclusion, these results suggest a persistent generation and activity of thrombin and cellular activation in these patients after MI.

Self-testing of oral anticoagulation is a new possibility related to the development of portable capillary whole blood prothrombin time monitors. The aim of this study was to evaluate one of this monitors, Coaguchek, with respect to its comparability with our routine prothrombin time determination system, as well as with the reference manual technique and two thromboplastins of high sensitivity, Manchester Reagent and one manufactured in our center, Thromboplastin Bilbao, in a group of patients on oral anticoagulant treatment. Although a correlation of r = 0.9271 was found between international normalized ratio (INR) values of Coaguchek and our routine method, Neoplastine/STA analyzer, the difference of the INR scatter increased with the magnitude of measurement, being lowest for INR between the portable monitor and Manchester Reagent and Thromboplastin Bilbao, with a similar coefficient of correlation, r = 0.8948 and r = 0.8905, respectively. A test was performed showing a 65.6% agreement with the INR values of the STA analyzer, 66.4% with Manchester Reagent and 73.4% with Thromboplastin Bilbao. On the basis of this correspondence with laboratory prothrombin time results Coaguchek may be considered as a possible option for monitoring anticoagulated patients even though patients should be given instructions and advice as regards the management and interpretation of the results.