<ORIGINAL ARTICLE>Characterization of a new coagulant enzyme isolated from Trimeresurus okinavensis (Himehabu snake) venom

A potent, proteinaceous inducer of coagulation factors, has been purified to homogeneity from Trimeresurus okinavensis (Himehabu snake) by ion exchange chromatography and molecular sieving. It has an apparent molecular weight of 28,000 and it specifically converts fibrinogen to fibrin through an enzymatic reaction. This activity was confirmed by a method using synthetic substrate S-2238, though the fraction from a DEAE sephacel column chromatography shows amidolytic activity of S-2251 and S-2366, which are commonly used to measure plasmin and activated protein C activity, respectively, as well as S-2238. This thrombin-like activity of the final product was not affect by the addition of heparin and AT-III. This enzyme also aggregates normal platelets. It is considered that this purified enzyme would be useful as a hemostatic agent or research reagent

Octreotide-Treated Diabetes Accompanied by Endogenous Hyperinsulinemic Hypoglycemia and Protein-Losing Gastroenteropathy

Occurrence of hypoglycemia in diabetes patients is very rare. We report here a case of frequent hypoglycemic attacks caused by inappropriate endogenous hyperinsulinemia in a female patient with poorly controlled diabetes and protein-losing gastroenteropathy. The blood glucose profiles of the patient were unstable. Results of the fasting test performed to investigate the cause of hypoglycemia suggested endogenous hyperinsulinism. Repeated selective arterial calcium injection tests suggested that hyperinsulinemia might be extrapancreatic in origin. However, efforts to detect a responsible lesion such as insulinoma were unsuccessful. Octreotide was used for the treatment of hypoglycemia and protein-losing gastroenteropathy. After treatment, although her leg edema caused by hypoalbuminemia persisted, hypoglycemia almost disappeared

Considerations for simultaneous detection of autoantibodies to coagulation factor and lupus anticoagulant

In patients with autoimmune coagulation factor deficiency (AiCFD), the production of autoantibodies that inhibit coagulation factors in the blood reduces the activity of those relevant coagulation factors, resulting in severe bleeding symptoms. Recently, reports of patients with AiCFD have noted the concomitant detection of lupus anticoagulant (LA), a risk factor for thrombosis. LA-positive patients may show bleeding symptoms due to decreased activity of coagulation factor II (FII) caused by autoantibodies against FII, in addition to thrombotic symptoms, a condition termed LA-hypoprothrombinemia syndrome (LAHPS). Anti-FII antibodies in LAHPS cases are frequently cleared antibodies that can be detected using immunological techniques, such as enzyme-linked immunosorbent assay (ELISA). Recently, several cases of coagulation FV inhibitors, known as autoimmune FV deficiency, have been reported. Some of these cases may be complicated by LA, which can cause thrombosis. False-positive results for anticoagulant inhibitors are known to occur in LA cases; therefore, immunological confirmation of antibodies against coagulation factors is recommended. Additionally, acquired hemophilia A (AHA), caused by autoantibodies against FVIII, is a typical acquired hemorrhagic diathesis, although affected patients may present with thrombosis associated with LA. Thus, it is important to remember that hemorrhagic diathesis due to autoantibodies against clotting factors can also result in thrombosis, as demonstrated by the co-detection of LA. When clotting factor inhibitors are detected in LA-positive individuals, it is important to confirm the presence of autoantibodies against coagulation factors using immunological methods, such as ELISA, to avoid false-positive results

Increase in plasma thrombin-activatable fibrinolysis inhibitor may not contribute to thrombotic tendency in antiphospholipid syndrome because of inhibitory potential of antiphospholipid antibodies toward TAFI activation

Background: The causes of thrombosis in antiphospholipid syndrome (APS) remain unknown, though several hypotheses in regard to hypofibrinolysis have been proposed. Objective: To clarify the mechanism, we measured plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI) in APS patients. Methods and Results: Both the TAFI antigen (TAFI:Ag) level measured with an ELISA, and thrombin-thrombomodulin-dependent TAFI activity (TAFI:Ac) were elevated in 68 APS patients as compared with those in 66 healthy controls, though they were lower than those in 46 patients with autoimmune diseases. As for the influence of antiphospholipid antibodies (aPL) on TAFI levels, the mean TAFI:Ac level in 39 SLE patients positive for APS was significantly lower than that in 27 SLE patients without APS, whereas there was no difference in TAFI:Ag between those groups. Furthermore, purified IgG from patients positive for aPL, and monoclonal aPL (EY2C9 and 23-1D) inhibited the activation of TAFI in a concentration dependent manner. Conclusion: These results suggest that aPL inhibits TAFI activation by affecting the function of thrombomodulin-thrombin complex through phospholipids. Although TAFI in plasma is elevated in autoimmune diseases including APS, we concluded that an elevated level is not likely a risk factor for thrombosis in APS patients, because of the inhibition of TAFI activation by aPL

Massive amounts of tissue factor induce fibrinogenolysis without tissue hypoperfusion in rats

Trauma-induced tissue factor (TF) release into the systemic circulation is considered to play an important role in the development of disseminated intravascular coagulation (DIC) immediately after severe trauma. However, the relationship between TF and hyperfibrinolysis, especially fibrinogenolysis, has been unclear. A total of 18 rats were divided into three groups: (a) the control group was infused with normal saline; (b) the low-dose group was infused with 4 U/kg TF; and (c) the high-dose group was infused with 16 U/kg TF. Arterial blood was drawn immediately and 2 and 4 h after the start of TF infusion. At each sampling point, arterial blood gases, platelet counts, and coagulation variables were measured. The fibrinogen degradation products were evaluated by a Western blot analysis. Hypotension, hypoxemia, and lactic acidosis were not observed in any of the three groups. In proportion to the doses of TF, the platelet counts, coagulation, and fibrinolysis variables deteriorated in line with DIC. The alpha 2-plasmin inhibitor levels significantly decreased in the high-dose group compared with the other groups. The amounts of fibrinogen degradation products increased in proportion to the doses of TF. The plasmin-alpha 2-plasmin inhibitor complex level in the high-dose group increased more than that of the other groups. In conclusion, TF can induce DIC associated with fibrinolysis and fibrinogenolysis without tissue hypoperfusion. The decrease in the alpha 2-plasmin inhibitor level and the significant increase in the plasmin level may be the two main factors underlying the pathogenesis of hyperfibrin(ogen)olysis after TF administration

Acquired Hemophilia A Developing Cerebral Infarction 36 Days after the Frequent Administration of Bypass Hemostatic Agents

A 74-years-old male who was a smoker and received treatment for hypertension, dyslipidemia, peripheral arterial disease and idiopathic interstitial pneumonia complained of subcutaneous hemorrhage of the right lower thigh. Marked anemia (hemoglobin 5.5 g/dL) and prolonged activated partial thromboplastin time (≥130 s) were noted. The factor VIII activity level was reduced to 1.2%, and the factor VIII inhibitor titer was 285.3 BU/mL, a diagnosis of acquired hemophilia A (AHA) was made. Then, hematomas of 5 intra-muscles were recurred. Hemostasis became difficult despite frequent and high-dose administration of recombinant human coagulation factor VIIa (total: 18 days, 305 mg). Hemostasis was achieved by switching to activated prothrombin complex concentrate (for 3 days, 18,000 units), however, cerebral infarction occurred after 36 days. After the frequent administration of bypass hemostatic agents on elderly AHA patients with several risk factors for ischemic stroke, the risk of subsequent thrombotic events may persist for 1 month