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The immunodepletion of factor VII from human plasma using a monoclonal antibody.

A murine hybridoma cell line which secretes monoclonal antibody to factor VII has been prepared to facilitate the immunodepletion of this clotting factor from plasma. Specific monoclonal antibody was purified from mouse ascites tumours by protein A-Sepharose chromatography and shown to be of the IgG1 immunoglobulin subclass. On immunoblotting, this antibody reacted with a single protein band identical to purified factor VII. The purified monoclonal antibody was coupled to Sepharose 4B and was used to immuno-deplete factor VII from pooled normal human plasma. The prothrombin time of plasma immunodepleted in this way was 35 s compared to 12 s for the starting plasma. Specific factor assays of the immunodepleted plasma showed factor VII activity to be less than 1% while the levels of the other clotting factors were unchanged. The immunodepleted plasma was equivalent to severe congenital factor VII deficient plasma as a substrate for factor VII assays. Bound factor VII could be eluted from the immunoaffinity column with citrate buffer, pH 6.0, with good recovery.

Animals↗

Combined factor VII and protein C deficiency found in a patient with peripheral pulmonary artery stenosis accompanied by progressive pulmonary hypertension and hemoptysis.

A congenital deficiency of factor VII and protein C was found in a 21-year-old female suffering from recurrent and progressive attacks of dyspnea and hemoptysis over the last four years. She has been followed in our Department since the age of 17 under a diagnosis of peripheral pulmonary artery stenosis and pulmonary hypertension as confirmed by cardiac catheterization and angiography. Prolonged prothrombin time repeatedly examined during this time period prompted us to perform detailed coagulation studies. We found that factor VII and protein C were both half normal in activity as well as in antigen. Three other members of her immediate family were also found to be affected with this combined deficiency. Since the genes encoding factor VII and protein C are located in different chromosomes, the 13th and the second chromosomes, respectively, expression of the combined hereditary deficiency is a random and very rare association on the basis of frequencies of 1:50,000 for factor VII and 1:16,000 for protein C deficiencies.

Adult↗

Evidence for tissue factor-dependent activation of the classic extrinsic coagulation mechanism in blood obtained from bleeding time wounds.

The activation of platelets and the coagulation mechanism was studied by collecting blood from a standard bleeding time incision at 30-second intervals and measuring the plasma concentrations of fibrinopeptide A (FPA), platelet factor 4 (PF4), and thromboxane B2 (TxB2). FPA was observed in the first samples (30 to 60 seconds) obtained, increased progressively until cessation of bleeding, and was markedly diminished after heparin administration, thus indicating that thrombin formation occurs early in incisional blood. PF4 increased monotonically throughout blood sampling, whereas the major increase in TxB2 appeared near the cessation of bleeding. The initial increase in FPA content occurred normally in patients with deficiencies of either factor IX or VIII, was markedly diminished in patients with factor X or V deficiency, and was delayed in patients with factor VII deficiency. These studies suggest that tissue factor activation of the classic (activation of factor X) extrinsic coagulation mechanism occurs as an early event during the arrest of bleeding from bleeding time incisions. The relation of the aforementioned to platelet activation is less clear because there was no consistent correlation between decreased FPA formation and impaired PF4 secretion or TxB2 production. In fact, the latter were normal in some subjects with the most impaired FPA formation, which suggests that both collagen and thrombin, perhaps synergistically, may contribute to platelet activation during the primary arrest of bleeding.

Biomechanical Phenomena↗

Deficiency of coagulation factors VII and XII in a patient with Hodgkin's disease.

A patient with Hodgkin's disease is described in whom deficiencies of coagulation factors VII and XII were discovered. Depressed levels of these factors appear to reflect increased Hodgkin's disease activity and returned to normal when chemotherapy was instituted. There was no evidence of accelerated fibrinolysis, intravascular coagulation, or circulating anticoagulants in the patient. Possible mechanisms for the abnormality include impaired production and/or increased consumption of coagulation factors. This observation suggests that all patients with lymphoreticular neoplasms should be screened carefully for clotting disturbances prior to treatment.

Adolescent↗

Thromboembolism in patients with hereditary deficiency of coagulation factors.

Despite significantly prolonged prothrombin time endogenously caused by factor VII deficiency, a 65-year-old woman suffered a fatal pulmonary embolism. This seemingly paradoxic phenomenon prompted our review of 14 other patients with various coagulation factor deficiencies who also had thromboembolic events. It is postulated that certain factor deficiencies may protect against venous and/or arterial thrombosis. A large-scale prospective study of this population may help define the relative importance of the various coagulation factors, platelets, and the vessel wall in thrombosis and atherogenesis and allow a rational evaluation of anticoagulant therapy.

Aged↗

Treatment of factor XI inhibitor using recombinant activated factor VIIa.

A 30-year-old female with severe factor XI deficiency of 0-2% acquired factor XI inhibitor following many infusions for fresh frozen plasma (FFP) for surgical procedures starting at 4 years of age. Seven months before this inhibitor was diagnosed, surgery was complicated by prolonged bleeding resistant to FFP, requiring epsilon aminocaproic acid (EACA) and surgical packing. The inhibitor was measured at 2.2 Bethesda units, 7 months since the last FFP. The inhibitor was confirmed as specific anti-XI and anti-XIa binding by patient's IgG to immobilized factor XI and factor XIa from whole plasma and purified IgG. For repair of a painful anterior cruciate ligament (ACL) defect she was given recombinant factor VIIa (rVIIa) at 90 mug kg(-1), starting one-half hour preoperatively and continued every 2 h for 8 h when haemostasis was complete. Thereafter the rVIIa was given every 3 h for two doses, and then every 4 h for four doses at which time she was discharged on EACA which was continued for 6 days. There was excellent haemostasis during and following the surgery. There was no evidence of consumptive coagulopathy, with no change in the fibrinogen, platelet count, or D-D dimer; and no increase of platelet factor 4, beta-thromboglobulin, or prothrombin fragment F 1.2. The thrombin-antithrombin complex increased over baseline after 24 h. There was no postoperative deep vein thrombosis or pulmonary embolus. In this patient with a factor XI inhibitor, the recombinant factor VIIa was effective and safe, ensuring adequate haemostasis with no thrombotic complications. This product which was designed for patients with inhibitors to factor VIII or factor IX, and factor VII deficiency, has now been given successfully to four patients with factor XI inhibitors.

Adult↗

[Clinical assessment of potential fields of application of recombinant factor VIIa in internal and pediatric diseases. Recommendations of an expert group].

Recombinant factor VIIa (rFVIIa) is increasingly used outside the labeled indications for treatment of life-threatening bleeding episodes after failure of the respective standard therapy. An interdisciplinary group of experts summarizes the state of knowledge of the use of rFVIIa in gastroenterology and hepatology, thrombocytopenia and -pathia, coagulation factor deficiencies, von Willebrand's disease, periinterventional bleeding without specific bleeding diathesis, drug-induced bleeding, disseminated intravascular coagulation, and neonatology. The most commonly used dose is 90 microg/kg body weight rFVIIa as bolus, if necessary followed by additional injections at intervals of 2-3 h. In factor VII deficiency lower dosages of 15-30 microg/kg body weight of rFVIIa are given every 4-6 h, whereas higher doses of 150-200 microg/kg body weight are used in neonates.

Adult↗

Molecular variant of factor VII.

Two patients with severe factor VII deficiency appeared to be different with respect to the presence of inactive factor VII-like material in their plasma. The inactive material, demonstrated in one patient's plasma and adsorbable onto BaSO4, inhibits the thrombotest-system and is capable of neutralizing a heterologous antibody against factor VII in a fluid phase system.

Cross Reactions↗

Characterization of a variant prothrombin in a patient congenitally deficient in factors II, VII, IX and X.

An 18-month-old child, who had no evidence of liver disease, malabsorption, or chronic ingestion of coumarin compounds, was found to have plasma deficiencies of factors II, VII, IX and X. Assays for factor II and X by immunological techniques (antibody neutralization and immunoelectrophoresis) revealed normal or elevated antigenic activity of these factors, suggesting the presence of abnormal protein variants in the patient's plasma. On two-dimensional immunoelectrophoresis of the patient's plasma in calcium, a normal and an abnormal population of prothrombin were seen. The abnormal prothrombin had a mobility more anodal than that of normal prothrombin, but less anodal than that of acarboxyprothrombin. The abnormal prothrombin, in contrast to acarboxyprothrombin, adsorbed readily to both aluminum hydroxide and barium citrate, and could be identified by two-dimensional immunoelectrophoresis of a barium citrate eluate. We suspect that the abnormal variant represents a partially carboxylated prothrombin.

Blood Coagulation Disorders↗

Recombinant activated factor VII (rFVIIa, NovoSeven).

Recombinant activated factor VII (rFVIIa, NovoSeven) enhances haemostasis in individuals, with its predominant action limited to areas of injury, apparently without systemic activation of the coagulation cascade. rFVIIa is currently licensed in most countries worldwide, for its use in the treatment of bleeding episodes in patients with hemophilia and the presence of inhibitors. Recently in the European Union, rFVIIa, has been approved for use in congenital Factor VII deficiency and Glanzmann's thrombasthenia. Furthermore, a large number of case series studies and anecdotal evidences, from patients with different bleeding conditions, have now shown that rFVIIa is actually a very valuable general haemostatic agent. It has been reported to reduce bleeding in patients with liver disease, thrombocytopenia/thrombocytopathia, trauma, spontaneous intracerebral hemorrhage and in the reversal of anticoagulant overdosage or toxicity. A number of trials have been carried out, which have shown that it is a relatively safe and well tolerated drug with a few episodes of unwanted thrombosis.

Blood Coagulation Disorders↗

Effects of inhibitors of arachidonic acid metabolism on thromboplastin activity in human monocytes.

Human isolated monocytes possess low levels of procoagulant activity, which was stimulated 10-30 fold by brief (2 hr) exposure to 10 micrograms/ml endotoxin. This activity was expressed in normal or factor XII-deficient plasma, but lost in plasma deficient in factors X or VII, indicating that it was due to thromboplastin. The stimulation of monocyte thromboplastin by endotoxin was inhibited in a dose-dependent manner by two phospholipase A2 inhibitors, 4-bromophenacyl bromide and quinacrine, and by two lipoxygenase inhibitors, eicosatetraynoic acid and nordihydroguaiaretic acid. Two cyclooxygenase inhibitors, aspirin and indomethacin, prevented endotoxin-induced increases in thromboxane B2 production but had no effect on thromboplastin production. These results suggest that a component in the sequence of lipid deacylation, arachidonic acid release, and metabolism via lipoxygenase may mediate the stimulation of monocyte thromboplastin activity by endotoxin.

Arachidonate Lipoxygenases↗