Haemostasis最新文献

Background: Paroxysmal nocturnal hemoglobinuria is a rare, clonal primitive hematopoietic cell disorder, often affecting middle-aged adults, including women of reproductive age. Major morbidity and mortality with this disease are often ascribed to the development of venous thromboembolism. We reviewed the current literature on the risk of venous thrombosis among nonpregnant and pregnant patients, and generated recommendations for the prevention of venous thromboembolism, as well as duration of treatment for affected patients who develop thrombotic disease.

Methods: We searched Medline for papers published between January 1966 and April 1999. We also requested relevant unpublished data from speakers who attended a recent international workshop of paroxysmal nocturnal hemoglobinuria. References from all primary data and review publications were also examined. Only English language publications were included. Event rates for venous thromboembolism and death were pooled using a random effect technique. Reports of paroxysmal nocturnal hemoglobinuria during pregnancy were summarized using descriptive statistics only.

Results: Thirteen retrospective studies of paroxysmal nocturnal hemoglobinuria in nonpregnant individuals were found. The rates of venous thrombosis varied considerably, but were reported to affect 14.4% of all individuals [95% confidence interval (CI) 7.6-25.5]. Among patients from western nations, venous thromboembolism seemed to develop at a higher rate (30.3%, 95% CI 26. 1-34.9). The majority of venous thromboembolic events were intra-abdominal, principally within the hepatic and mesenteric veins. The likely cause of death among patients with paroxysmal nocturnal hemoglobinuria was described in nine studies: 22.2% of fatalities were due to venous thrombosis (95% CI 11.8-38.0), more commonly in western countries (event rate 37.2%, 95% CI 21.6-56.0). Another 20 published reports described the outcome of 33 pregnant women with paroxysmal nocturnal hemoglobinuria. Two women developed venous thromboembolism during pregnancy and another 2 during the postpartum state for a combined event rate of 12.1% (95% CI 3.4-25.2), three of which resulted in death. The all-cause mortality rate was 20.8% (95% CI 7.3-39.0). Both anemia (event rate 72.7%, 95% CI 56.5-86.3), and thrombocytopenia (event rate 27.3%, 95% CI 13.7-43.5) were common, often necessitating red cell or platelet transfusions. Almost half of all infants (54.8%, 95% CI 36.1-72.7) were delivered preterm, and had a mean live birth weight of 2,800 g. Three of 34 reported births ended in death (perinatal mortality rate 8.8%, 95% C 1.9-23.7).

Conclusion: In accordance with the apparently high rate of venous thrombosis among pregnant and nonpregnant individuals with paroxysmal nocturnal hemoglobinuria, especially for fatal thrombosis, we developed practical recommendations for the prevention and treatment

Objective: To asses endothelial function and variables of fibrinolysis and coagulation in smokers compared to healthy controls.

Methods: Flow-associated dilation as a marker for peripheral endothelial function and intima media thickness as a marker for early morphologic vascular changes were measured in otherwise healthy smokers (n = 30, 16 males and 14 females, age: 40.6 +/- 11.3 years, body mass index 24.9 +/- 3.7 kg/m(2)) and non-smoking controls matched for age and sex using high-resolution ultrasound. Variables of the coagulation system (thrombin-antithrombin III complex, fibrinogen) and fibrinolysis (tissue-plasminogen activator, plasmin-alpha(2)-antiplasmin complex) were determined by ELISA and plasminogen activator inhibitor activity by means of a chromogenic substrate test.

Results: Compared to the non-smoking controls, flow-associated vasodilatation was significantly reduced (6.9 +/- 4. 4 vs. 10.5 +/- 6.2%, p = 0.01) and intima media thickness tended to be increased (0.58 +/- 0.12 vs. 0.52 +/- 0.14 mm, p = 0.08) in smokers. The thrombin-antithrombin III complex, fibrinogen, plasmin-alpha(2)-antiplasmin complex, tissue-plasminogen activator and plasminogen activator inhibitor activity did not differ between smokers and controls.

Conclusion: Our data indicate that peripheral endothelial dysfunction is common in smokers even without major alterations in molecular markers of the coagulation and fibrinolysis system.

To investigate how thrombin time, activated partial thromboplastin time (APTT) and prothrombin time are influenced by fibrinogen degradation products (FDP), different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8 and 1.0 mg/ml) of the purified FDP X, Y, D and E were added to the plasma of healthy dogs. If fragment Y was added to the plasma a considerable inhibitory effect could be demonstrated for all three test systems. A significant prolongation (p < 0.05) was found for concentrations of > or =0.1 mg/ml (thrombin time, APTT) and > or =0.2 mg/ml (prothrombin time). With FDP Y concentrations from >0.185 mg/ml (prothrombin time) to >0.24 mg/ml (APTT) coagulation time was prolonged beyond the respective reference range. As regards the other fragments, a comparable inhibitory effect could only be shown for fragment X added to the thrombin time test system. This effect can most probably be explained by the competition of the FDP X and fibrinogen for the fibrinogen binding sites of thrombin, rather than by a fibrin polymerization disorder. The results demonstrate that for plasma with normal fibrinogen concentration the group tests are only prolonged beyond the reference range at FDP concentrations very rarely found in spontaneous hyperfibrinolysis.

Platelet adhesion to vascular subendothelium under conditions of high shear stress is mediated by the platelet glycoprotein (GP) Ib-von Willebrand Factor (vWF) interaction. The aim of this study was to characterize the murine monoclonal antibodies (MoAbs) 27A10 and 28E6, both raised against purified GPIb. The MoAb 27A10 is a potent inhibitor of shear-induced platelet adhesion to collagen type I in a flow chamber at shear rates of 1,300 and 2,700 s(-1). 20 microg/ml of MoAb 27A10, furthermore, could completely block shear-induced aggregation in a modified Couette viscometer at shear rates of 1,000 and 4,000 s(-1). On the other hand, MoAb 27A10 had a negligible effect on botrocetin-induced GPIb-vWF binding and is only a poor inhibitor of the ristocetin-dependent interaction. In contrast, MoAb 28E6 did abolish both the ristocetin- and botrocetin-induced GPIb-vWF binding, whereas it did not block the shear-induced interaction. Thus, we identify here two anti-GPIb MoAbs 27A10 and 28E6 that either preferentially inhibit the shear-induced or the ristocetin/botrocetin-induced platelet-vWF interaction. With these tools it should be possible to more clearly define the mechanisms by which platelets bind to vWF in vivo.

In this study, fibrinogen measurements according to the Clauss method, photometric method and Jacobsson method have been investigated to find out how they are influenced by adding in vitro the purified canine fibrinogen degradation products (FDP) X, Y and D. Test results according to the Clauss method were found to be underestimated if the fragments X, Y and D were added while measurements according to the Jacobsson method turned out to underestimate the real fibrinogen concentration if the FDP Y and D were added. The Clauss method was particularly sensitive towards FDP. Results were considerably underestimated even with a quantity as little as 0.05 g FDP Y or FDP D/g fibrinogen (p < 0.05). The photometric method was only affected by FDP X leading to false high results. If FDP X was added, fibrinogen values were also overestimated with the Jacobsson method. Our results demonstrate that the photometric method is the most accurate.

Inherited gene defects related to the coagulation system have been reported as risk factors for stroke. Recently, a genetic component in the factor V (FV) gene that contributes to activated protein C resistance both in the presence and absence of FV 1691 G-->A was reported. This highly conserved FV gene haplotype was marked as R2 polymorphism, an A to G alteration at position 4070 in exon 13 that predicts the His 1299 Arg substitutions. The aim of this study was to evaluate the role of this mutation in Turkish children with ischemic infarct. The case-control study included 48 patients with cerebral infarction; all were 18 years of age or younger (range: 10 months to 18 years). Ten (20.8%) of the 48 patients were found to carry the FV 1299 His-->Arg mutation, one being homozygous. One patient who had a combination of FV 1691 G-->A and protein C deficiency also carried the FV 4070A mutation. A homozygous FV 1299A patient had a prothrombin (PT) 20210A mutation in the heterozygous state. The cerebral infarct risk for FV 1299 was found to be 2.4 (95% confidence interval 0.9-6.8) for all groups. When underlying conditions were excluded, the incidence of FV 1299 was found to be 8/35 (22.8%), but the risk was almost the same. When two other common thrombophilic mutations (i.e. FV 1691 G-->A and PT 20210 G-->A) were excluded, the incidence of FV 4070 mutation increased to 7/21 (33.3%). The risk also increased to 3.9 (95% confidence interval 1.2-12.3).

Studies have shown subcutaneous low- molecular-weight heparin (LMWH) to be at least as safe and efficacious as intravenous unfractionated heparin (UFH) for the treatment of venous thromboembolism (VTE). Furthermore, unlike UFH, LMWH is administered on a once- or twice-daily basis without monitoring in uncomplicated cases. Consequently, it has been suggested that the large majority of patients with VTE could be treated on an outpatient basis. Exceptions include patients with an increased risk of haemorrhage, pregnant women, children and those with renal insufficiency. Outpatient management would offer economic advantages and be more convenient for both the patient and the hospital staff.