A simple and quantitative method for the determination of tissue factor.

Tissue factor (TF), a potent initiator of the extrinsic coagulation pathway, is believed to have a critical role in thrombogenesis and haemostasis. To elucidate the role of TF in the development of various syndrome, we developed a quantitative assay method for the determination of TF using FIX complex (Profilnine) and the synthetic chromogenic substrate S-2238, all of which are commercially available. The method is simple, very sensitive, good linearity and applicable to the tissue culture plate, indicating its promising usage for the quantitation of TF activity of cells.

Surface and total tissue factor activity of endothelial cells.

With a technic that was developed by us, we found that normal human umbilical vein endothelial cells (HUVEC) in culture characteristically had very little tissue factor (TF) activity either on the surface or in the cells which had been disrupted. In the presence of endotoxin (E. coli O26:B6), a trigger for thrombosis in septicemic patients, we could not detect an increased TF activity of HUVEC on its surface. However, an increase in TF (total TF) was detected after disruption of the cells. The increase in total TF was dose-dependent. Endotoxin at the concentration of 10 micrograms/ml caused around 5 fold increase in total TF activity compared to that of HUVEC in the absence of endotoxin.

A double-blind placebo control trial of dilazep in beta-thalassemia/hemoglobin E patients.

Since the obtained results from the pilot study indicated that dilazep which was a membrane stabilizer would be benefit to treatment and prevention of anemia and chronic leg ulcer in beta-thalassemia/hemoglobin E (beta-thal/HbE) patients, the authors had continued the study in a second phase, ie a double blind placebo control trial. Twenty-seven beta-thal/HbE patients were recruited in the study. Eight patients who suffered from chronic leg ulcer were given dilazep. The rest of patients were given dilazep or placebo according to a randomized table. Hence, 16 patients received dilazep and 11 received placebo. When we compared the number of unit of blood transfusion, hemoglobin level, 2-3 DPG and P50 value between the dilazep and placebo groups using unpaired t-test, we found that there were no statistical differences in any of the parameters. However, when we compared the data within the group using paired t-test, there was statistical decrease in blood requirement after treatment in the dilazep group (p < 0.05). Concerning with the treatment of chronic leg ulcer, 3 in 8 patients were completely healed within 3 months, 4 in 8 patients were improved and 1 in 8 patients was not improved. There were complaints of skin itching and mild epigastric pain in placebo group but the liver function tests, kidney function tests and cardiac enzyme did not significantly change during the medication.

Effect of different oral anticoagulant intensities on prothrombin fragment 1 + 2 in Thai patients with mechanical heart valve prostheses.

The minimal intensity of oral anticoagulant required for antithrombotic protection in patients with a mechanical heart valve is still debatable, and that of the Westerner may not be directly applied to Thai patients. Our preliminary clinical review suggested that International Normalized Ratio (INR) 2-3 might be enough but it needs further supporting evidence. Therefore, we studied the effect of different anticoagulant intensities, expressed as INR, on the in vivo coagulation activation by measuring prothrombin fragment 1 + 2 (F1 + 2) in 116 patients with mechanical heart valve replacements. The patients had received warfarin for not less than one month with different intensities. The mean +/- S.D. of F1 + 2 level in 30 normal controls was 0.7 +/- 0.17 nmol/L. After excluding two outliers, the maximum linear correlation between INR and F1 + 2 was -0.658 (p < 0.001) when only patients whose intensities were lower than INR3 were taken into account. Adding more data from the patients having higher intensities decreased the correlation coefficient. The patients were subsequently classified by INR values in the range INR 1.1-1.9, 2-3 and 3.1-4.2. The F1 + 2 in each group was 0.6 +/- 0.30, 0.28 +/- 0.13 and 0.24 +/- 0.13 nmol/L respectively. The F1 + 2 in the first group did not differ from normal (p = 0.119) but was higher than the others (p = 0.000). The latter two groups had no difference between them (p = 0.112). Hence, from the laboratory point of view, we did not see additional benefit in the reduction of thrombin activation by the anticoagulant intensities higher than the range INR 2-3. The evidence supported that this therapeutic range might be enough for Thai patients with mechanical heart valves.

Laboratory assessment of thrombolytic therapy in acute myocardial infarction.

Hemostatic profiles and cardiac enzymes were studied in 55 acute myocardial infarct (AMI) patients to assess SK and rt-PA therapy. Hypofibrinogenemia occurred 85% in SK group and 55% in rt-PA group with high FDP and D-Dimer, indicating systemic fibrinogenolysis and local crosslinked fibrin clot lysis. The incidence of bleeding in SK and rt-PA groups combined with anticoagulants were the same but lower in rt-PA with antiplatelet. The mean FDP was significantly higher in the bleeding group (p < 0.01). Cardiac enzymes: CK, CK-MB peak values indicated reperfusion were 26.6%, 60% and 90% in conventional, SK and rt-PA therapy, respectively. Early and late occlusion did not occur either in SK or rt-PA followed by anticoagulants. Late occlusion was found in patients treated with rt-PA and antiplatelet. Mortality rate was 20% in conventional therapy.

Bernard-Soulier syndrome: a case report.

An adopted Thai girl has been followed at Children's Hospital, Bangkok, since she was 8 months old. The diagnosis of Bernard-Soulier syndrome was made, based on the clinical features of easy bruising, purpura, petechial hemorrhages and recurrent epistaxis. The abnormal laboratory tests included giant platelets with dark stained granules, mild to moderate thrombocytopenia, prolonged bleeding time, absence of ristocetin induced agglutination but normal ristocetin cofactor, factor VIII coagulant activity and von Willebrand factor antigen. These findings suggested the absence of glycoprotein Ib (GPIb) on the platelet membrane. The genetic transmission can not be evaluated in this patient.