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Background: A severe deficiency of ADAMTS13 activity contributes to the pathogenesis of thrombotic thrombocytopenic purpura (TTP). Measuring the activity of ADAMTS13 is helpful for the diagnosis of TTP and the prognostic monitor in TTP patients. Most available assays are cumbersome and costly, so not easily adapted to routine laboratories. ADAMTS13 cleaves von Willebrand factor (VWF) within the domain A2, located between domains A1 and A3. Therefore, specific assays for ADAMTS13 activity could be based on the different structures of VWF before and after the cleavage. Using this hypothesis we try to establish a new and simple method to determine ADAMTS13 activity., Methods: First, plasma samples were exposed in denaturing condition to allow cleavage of VWF by ADAMTS13. Then, the ADAMTS13 activity was measured with two novel monoclonal antibodies, SZ-129 and SZ-125, which specifically recognize the VWF A1 and A3 domains by using a two-site sandwich ELISA. Compared with a residual-collagen binding assay (R-CBA), plasma ADAMTS13 activities in 161 samples were assessed, and the inhibitory activities of ADAMTS13 autoantibody in 24 TTP patients were determined. The relationship of these two assays was analyzed by linear correlation, and the sensitivity and specificity of the new assay was also evaluated., Results: Plasma ADAMTS13 activities in normal people and TTP, acute myocardial infarction (AMI), and idiopathic thrombocytopenic purpura (ITP) patients determined by the new assay were (89.75 +/- 7.93)%, (17.63 +/- 18.71)%, (68.55 +/- 18.08)%, (85.83 +/- 9.84)%, respectively. Results were consistent with those of R-CBA, the squared correlation factor was 0.9183 of the two assays. The new assay can easily discriminate a TTP plasma sample from a non-TTP plasma sample (P < 0.01), and the coefficient of variation for the new assay was 6.17%. In 23 idiopathic TTP patients, the inhibitor activity of ADAMTS13 autoantibody ranged from 12% to 100%, while no inhibitory activity was detected in one hereditary TTP patient., Conclusion: This new and simple assay for ADAMTS13 activity could be used routinely in the clinic to determine the activity of ADAMTS13.

Background: Hypertrophic cardiomyopathy (HCM) is a form of cardiomyopathy with an autosomal dominant inherited disease, which is caused by mutations in at least one of the sarcomeric protein genes. Mutations in the beta-myosin heavy chain (beta-MHC) are the most common cause of HCM. This study was to reveal the disease-causing gene mutations in Chinese population with HCM, and to analyze the correlation between the genotype and phenotype., Methods: The exons 3 to 26 of MYH7 were amplified by PCR, and the PCR products were sequenced in five non-kin HCM patients. A 17-year-old patient was detected to be an Arg723Gly mutation carrier. Then his family was gene-screened, and the correlation between genotype and phenotype was analyzed., Results: The mutation of Arg723Gly in a Chinese family with HCM was detected for the first time. With a C-G transversion in nucleotide 13,619 of the MYH7 gene, located at the essential light chain interacting region in S1, the replacement of arginine by glycine took place at amino acid residue 723. A two-dimensional echocardiogram showed moderate asymmetrical septal hypertrophy with left atria enlargement. There was no obstruction in the left ventricular outflow tract. In his family, a total of 13 individuals were diagnosed HCM and 5 of them were dead of congestive heart failure at a mean age of 66-year-old. Eight living members were all detected to carry the mutation, in which 3 developed progressive heart failure. Moreover, the heart function of the people evidently deteriorates when their age are older than 50. The mutation and the disease show co-separated., Conclusion: The Arg723Gly mutation is a malignant type. In Chinese the mutation has the similar characters to the former report but has low degree malignant.

Objective: To measure plasma thrombospondin1 (TSP1) in thrombotic thrombocytopenic purpura (TTP) and other diseases such as idiopathic thrombocytopenic purpura (ITP), systemic lupus erythematosus (SLE), myocardial infarction, brain infarction, and malignant tumor et al. and 8 patients after bone marrow transplantation (BMT) were also investigated. Then to study on the relationship between TSP1 and von Willebrand factor cleaving protease (ADAMTS13); and to identify the significance of plasma TSP1 in TTP., Methods: TSP1 was measured by a commercial kit and the activity of ADAMTS13 was evaluated by residue collagen binding assay., Results: TSP1 in TTP plasma before plasma exchange or plasma infusion was 6.49 mg/L, and stepping up to 13.02 mg/L after therapy, but still significantly lower than 18.34 mg/L in normal control. While the decrease in different degree of ADAMTS13 activity was observed from 0%-52%, and there were 8 samples whose activity of ADAMTS13 were no more than 10%; the different extent of increase in those patients after therapy was demonstrated to be 2.9%-93.4%, only one patient's ADAMTS13 activity was below 10%. The activity of ADAMTS13 in some ITP and SLE patients were mildly decreased (63% +/- 16% and 70% +/- 14% respectively), TSP1 were also decreased (16 mg/L +/- 8 mg/L). TSP1 in patients of myocardial infarction and brain infarction were increased (24.0 mg/L +/- 2.9 mg/L), while ADAMTS13 activity had no significant change (72% +/- 16%). Same things happened in BMT patients., Conclusion: There was some concordance between the decrease of ADAMTS13 activity and TSP1 in plasma of TTP patients. And the change of TSP1 was restricted to TTP. TSP1 may contribute to the episode of TTP in a still unclear fashions.