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Han-Mou Tsai

Publications and source records attributed to Han-Mou Tsai.

30 records · Page 2Linked to original sources
PubMed2002

Ultralarge von Willebrand factor multimers and normal ADAMTS13 activity in the umbilical cord blood.

INTRODUCTION: Recent studies demonstrate that deficiency of ADAMTS13, the metalloprotease that cleaves von Willebrand factor (VWF) in a shear-dependent manner, causes thrombotic thrombocytopenic purpura (TTP). Previously, ultralarge multimers of VWF were detected in the fetuses, the umbilical cords and the newborns. However, the significance of this finding is unknown. MATERIALS AND METHODS: The activity of ADAMTS13 and the multimer pattern of VWF in the cord blood, as well as the VWF antigenic and ristocetin cofactor levels, were analyzed using previously published methods. The presence of ultralarge multimers was determined by densitometric analysis. RESULTS: On the average, the level of VWF antigen and ristocetin cofactor activity are slightly increased in the newborns (mean+/-standard deviation, 1.66+/-0.76 and 1.45+/-0.64 U/ml, respectively). Ultralarge VWF multimers are detected in 11 of 17 umbilical cord plasma samples. However, the ADAMTS13 is normal (0.99+/-0.15 U/ml) in all but one sample in which it is mildly decreased (0.71 U/ml). CONCLUSIONS: Since ADAMTS13 activity is normal, we speculate that the presence of ultralarge multimers in the umbilical cord blood may be due to the low levels of shear stress in the umbilical circulation. These results may have important implications for understanding the manifestation of ADAMTS13 deficiency during the neonatal period.

ADAM Proteins↗
PubMed2002

Inhibitors of ADAMTS13: a potential factor in the cause of thrombotic microangiopathy in a renal allograft recipient.

BACKGROUND: Thrombotic microangiopathy (TMA) is a well-known complication after renal allograft transplantation. In most cases, calcineurin inhibitor is believed to play a role in the development of this disorder. Recent studies have shown that a deficiency in the activity of the von Willebrand factor-cleaving metalloprotease ADAMTS13 causes thrombotic thrombocytopenic purpura. A similar mechanism occurring in patients who develop TMA after renal transplantation has not been described. METHODS: Analysis of plasma samples from a patient who developed TMA after receiving a cadaveric renal allograft revealed undetectable ADAMTS13 activity and the presence of its inhibitors. RESULTS: Discontinuation of cyclosporine and daily plasma exchange increased the ADAMTS13 activity, which was followed by resolution of the microangiopathic hemolysis and improvement of the graft function. At 3-month follow-up, the ADAMTS13 activity remained in the normal range and no inhibitors were detected. CONCLUSIONS: This is the first case to demonstrate a correlation between the presence of ADAMTS13 inhibitors and transplant-associated TMA. Autoimmune inhibitors of ADAMTS13 should be considered in patients with transplant-associated thrombotic microangiopathy. The role of calcineurin inhibitor in the formation of autoantibodies to ADAMTS13 remains to be explored.

Cyclosporine↗
PubMed2002

Von Willebrand factor, ADAMTS13, and thrombotic thrombocytopenic purpura.

Von Willebrand factor (vWF), a glycoprotein critical for supporting platelet adhesion and aggregation at sites of vessel injury, exists in the plasma as a series of multimers. Recent studies have shown that a metalloprotease cleaves endothelial vWF to a series of multimers. A deficiency of the protease activity due to autoimmune IgG inhibitors or genetic mutations is associated with thrombotic thrombocytopenic purpura (TTP). Positional cloning based on kindreds with a genetic deficiency of the protease and amino acid sequencing of the purified protein have identified the protease as a novel member of the ADAMTS (a disintegrin and metalloprotease with thrombospondin type 1 repeat) zinc metalloprotease family located on the long arm of chromosome 9. Mutations of the gene are detected in patients with the congenital form of TTP. These findings support the view that vWF proteolysis is critical in regulating vWF-platelet interaction and set the stage for improving the diagnosis and treatment of thrombotic thrombocytopenic purpura.

ADAM Proteins↗
PubMed2002

Transfusion of polymerised human haemoglobin in a patient with severe sickle-cell anaemia.

Many patients with sickle-cell anaemia have red-cell alloantibodies. We could not obtain compatible blood for a 40-year-old woman with a sickle-cell crisis after a hip operation. We transfused a polymerised human haemoglobin solution, after which the patient's pain was alleviated. This treatment, in combination with erythropoietin, resulted in a rise in our patient's haemoglobin concentration, and her eventual recovery. Increased oxygen delivery to the microcirculation might have contributed to the rapid resolution of pain after the transfusion.

Adult↗
PubMed2002

Warm-antibody autoimmune hemolytic anemia developing after thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) and warm-antibody autoimmune hemolytic anemia (AIHA) are uncommon diseases. Although TTP has been increasingly described in association with autoimmune antibodies, there are very few reports of the association with autoimmune hematological conditions, including idiopathic thrombocytopenic purpura and AIHA. Here we describe a patient with classic manifestations of TTP, who was successfully treated with plasma exchange. A few weeks later, she developed warm-antibody AIHA, which responded promptly to prednisone.

Adult↗
PubMed2002

Deficiency of ADAMTS13 in thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura, characterized by the presence of systemic hyaline thrombi in the arterioles and capillaries, is a potentially fatal disease that responds to plasma infusion or exchange. Recent studies have demonstrated that a metalloprotease in the normal plasma cleaves endothelial von Willebrand factor to a series of multimers. A deficiency of the protease, due to autoimmune IgG inhibitors or genetic mutations, is detected in patients with thrombotic thrombocytopenic purpura. Positional cloning based on kindreds with a genetic deficiency of the protease and amino acid sequencing of the purified protein have identified the protease as a novel member of the ADAMTS (a disintegrin and metalloprotease with thrombospondin type 1 repeat) zinc metalloprotease family located on the long arm of chromosome 9. Mutations of the gene are detected in patients with the congenital form of thrombotic thrombocytopenic purpura. In the circulation, proteolysis of von Willebrand factor is critical in regulating vWF-platelet interaction. These advances in knowledge provide the basis for a rational approach to improving the diagnosis and treatment of thrombotic thrombocytopenic purpura.

ADAM Proteins↗
PubMedDate not supplied

Rituximab therapy for refractory thrombotic thrombocytopenic purpura.

While most patients of thrombotic thrombocytopenic purpura (TTP) respond to plasma exchange and achieve remission, a subset of the patients experience multiple relapses or develop a persistent disease that may be debilitating and life threatening. We report the experience of rituximab treatment in three consecutive patients who had required periodic plasma exchange for greater than 50-180 days after failing other modalities of treatments. Two patients each received eight doses of rituximab infusion and had clinical remissions that have lasted for 23 months and ongoing in one patient and for 17 months before relapse in the other. The third patient received four doses of rituximab infusion and had improvement of disease for 60 days until her death from unrelated causes. Analysis of the von Willebrand factor-cleaving metalloprotease activity (ADAMTS13) and its inhibitor in two patients showed that rituximab treatment was associated with a rise of the protease level and a decrease of the inhibitor titers in one patient who achieved clinical remission and a decrease of the inhibitor titer but no increase in protease level in the other patient who had a partial response. Based on the responses to rituximab and its mild toxicity in these three patients, and the lack of effective alternative treatments, additional exploration of the role of rituximab in the treatment of refractory TTP is warranted.

ADAM Proteins↗