Recombinant factor VIIa (Novoseven) restores deficient coagulation: experience from an ex vivo model.

The action of recombinant factor VIIa (rFVIIa) in coagulation deficiencies with increased risk of bleeding was investigated using in vitro perfusion. Blood samples were drawn from healthy donors, a patient with hemophilia A and inhibitors, and six patients undergoing oral anticoagulant treatment. Fragmin 10 U/mL was used as anticoagulant. rFVIIa (10 microg/mL in plasma) was added to blood samples, incubated for 1 minute at 37 degrees C, and perfusion studies performed for 10 minutes at 600 x s(-1) through annular chambers containing damaged vascular segments. Subendothelial fibrin and platelets were expressed as a percentage of subendothelial surface screened. Under different conditions, rFVIIa consistently restored or improved fibrin formation on the damaged vascular subendothelium exposed to circulating blood. It restored fibrin deposition in blood from the hemophilia A patient; in patients undergoing acenocoumarol treatment, it reduced the international normalized ratio (INR) from 2.47 to 1.25 with a significant increase in fibrin deposition. Platelet deposition varied slightly between clinical conditions but was less evident in the hemophilia A patient. These data support the concept that rFVIIa facilitates fibrin formation in these clinical situations, promoting procoagulant activity at sites of vascular damage where tissue factor is exposed. This could improve hemostasis in patients with hemophilia A and inhibitors, and in patients treated with oral anticoagulants.

[Hemorrhagic incidents during prolonged ambulatory treatment with acenocoumarol]. / Accidentes hemorrágicos durante el tratamiento ambulatorio prolongado con acenocumarol.

BACKGROUND: To analyze hemorrhagic complications in a series of outpatients treated with acenocoumarol in an anticoagulant specialized unit by a prospective observational clinical study. PATIENTS AND METHODS: 1,200 outpatients (682 women/518 men, mean age 54.6 +/- 15.8 yrs.) treated with acenocoumarol for at least 6 weeks, with a total follow-up of 2,795 patients-yr. Prevalence and incidence of bleeding was analyzed. The episodes that were potentially life-threatening, or forced to blood transfusion or hospital patient admittance were considered as major bleedings, and the remainder episodes were minor. RESULTS: There were 379 minor bleedings in 258 patients (incidence 13.56/100 patients-yr.), 45 major bleedings (1.61/100 patients-yr.) and 2 lethal bleedings (0.07/100 patients-yr.). Minor bleedings correlated with more advanced age (57.3 +/- 11.8 vs. 53.9 +/- 16.7 yrs., p = 0.002), with the first two months in treatment in the 511 patients who start the treatment during the study (31.09 vs. 13.04/100 patients-yr., p < 0.001), and with a worse achievement of the desired anticoagulation (72.4% vs. 81.6%; p = 0.002). Major bleeding was associated with local causes in 48.9%, and with an excessive anticoagulation in 35.6%. CONCLUSIONS: Bleeding is relatively frequent during acenocoumarol therapy, mainly in patients with worse control, but only in a few of these episodes is severe, and is usually associated with local lesions.

Inhibition of human platelet aggregation by the proteolytic effect of streptokinase. Role of the human factor-VIII-related protein.

Defective ADP-induced aggregation was observed in in vitro streptokinases(SK)-treated normal platelet-rich plasma. Classic haemophilia and normal platelet poor plasma (PPP) treated with SK inhibit the aggregation of washed platelets; plasmin-treated normal human serum also shows an inhibitory effect on platelet aggregation. However, SK-treated von Willebrand plasmas do not inhibit the aggregation of washed platelets. This confirms the fact that the anti-aggregating effect is mainly linked to the digested factor VIII) but not to the digested fibrinogen. Defective ristocetin-induced platelet aggregation has also been observed in SK-treated plasmas. The presence of normal PPP does not modify the inhibition of the ADP-induced aggregation of washed platelets in SK-treated PPP. However, it does correct the ristocetin-induced aggregation. These results suggest that the inhibition of the ADP-induced aggregation is caused by the factor VIII degradation products, while the inhibition of the ristocetin-induced aggregation appears because of a defective von Willebrand activity of the factor VIII molecule.

Functional renal failure and haemorrhagic gastritis associated with endotoxaemia in cirrhosis.

Forty-three patients with cirrhosis and ascites, 21 with normal renal function, 10 with a progressive functional renal failure (FRF), and 12 with a steady FRF, were investigated for the presence of endotoxaemia by the Limulus lysate test. Endotoxaemia was found in nine patients with FRF and in none of the 21 with normal renal function (P less than 0-01). A positive Limulus test was almost exclusively associated with a progressive FRF (eight of 10 patients) and all but one of them died. Renal function improved as endotoxaemia disappeared in the survivor. Endotoxaemia was also associated with haemorrhage due to acute erosions of the gastric mucosa, being present in six of the seven patients who had this complication. Intravascular coagulation was not found in any patient. The Limulus test was positive in the ascitic fluid in 18 of 21 patients tested, although only two of them had peritonitis. These results suggest that endotoxaemia may play a critical role in the development of progressive renal failure and haemorrhagic gastritis in cirrhosis, and emphasise the potential risk of procedures involving reinfusion of ascitic fluid.

A variant of Glanzmann's thrombasthenia which fails to express a GPIIb-IIIa related epitope that is recognized by a specific monoclonal antibody (C17).

Binding of different antibodies to the GPIIb-IIIa complex in resting (AP2, EDU3, C17) or activated platelets (PAC1) was studied by flow cytometry in a patient with a platelet defect involving GPIIb-IIIa related functions. The patient has a mild history of bleeding. Aggregation induced by ADP and collagen were absent but normal response was obtained with ristocetin. Platelets from the patient do not bind fibrinogen. Perfusion studies with flowing blood showed that patient's platelets have a marked impairment in the process of spreading and aggregate formation on vascular subendothelium. Electrophoretic studies in SDS-polyacrylamide gels demonstrated the presence of normal amounts and normal mobility of GPIIb-IIIa. Fibrinogen was present in the patient's platelets (68-74% of controls). The binding of AP2 and EDU3 to patient's resting platelets was normal as assessed by flow cytometry. In contrast, a decreased presence of the C17 antigen (10 fold lower than control platelets) was detected in resting platelets and a markedly reduced binding of PAC1 was found in thrombin activated platelets. These studies suggest that C17 recognizes an epitope of the GPIIb-IIIa in resting platelets that is implicated in the regulation of adhesive and cohesive properties of GPIIb-IIIa. Studies on this patient might be helpful for the understanding of GPIIb-IIIa functions.

The 4G/5G polymorphism of the type 1 plasminogen activator inhibitor gene and thrombosis in patients with antiphospholipid syndrome.

OBJECTIVE: To investigate the relationship between the 4G/5G polymorphism of the type 1 plasminogen activator inhibitor (PAI-1) gene and thrombotic manifestations in patients with antiphospholipid syndrome (APS). METHODS: We studied a total of 247 patients included in the following 4 groups: 70 patients with primary APS, 104 patients with systemic lupus erythematosus (40 with antiphospholipid antibodies [aPL] and clinical [secondary] APS, 13 with aPL but without clinical APS, and 51 with neither detectable aPL nor a history of thrombosis), 14 asymptomatic individuals with aPL, and 59 patients with thrombosis but without known thrombosis risk factors. A control group of 100 healthy individuals was also analyzed. PAI-1 4G/5G polymorphism was determined by polymerase chain reaction and endonuclease digestion. RESULTS: The allele frequency of 4G/5G in controls was 0.47/0.53. There were no differences in allele distribution among patient groups or between patients and controls. However, a higher frequency of the 4G allele was observed in APS patients with versus those without thrombosis (0.57 versus 0.39; P < 0.05) (odds ratio [OR] 2.83, 95% confidence interval [95% CI] 1.18-6.76). This higher frequency of the 4G allele was attributable to the higher frequency in patients with versus those without arterial thrombosis (0.64 versus 0.43; P < 0.01) (OR 5.96, 95% CI 1.67-21.32), while patients with venous thrombosis had an allele distribution similar to that of those without venous thrombosis (0.49 versus 0.50; P not significant). There was a trend toward higher PAI-1 antigen and activity levels in APS patients and controls with the 4G/4G genotype, but this did not reach statistical significance. CONCLUSION: The presence of the 4G allele of the 4G/5G polymorphism of the PAI-1 gene may be an additional risk factor for the development of arterial thrombosis in APS.