INVESTIGADORES
AMARAL Maria Marta
congresos y reuniones científicas
Título:
Virtual decrease of von Willebrand factor-cleaving protease (ADAMTS13) after infusion desmopressin (DDAVP)
Autor/es:
FARÍAS CRISTINA; KEMPFER, ANA C; AMARAL MARÍA M; WOODS ADRIANA I; NADAL VICTORIA; CARBALLO GONZALO A; MESCHENGIESER SUSANA S; LAZZARI MARÍA A
Lugar:
Birmingham
Reunión:
Congreso; XIX CONGRESS. THE INTERNATIONAL SOCIETY ON THROMBOSIS AND HAEMOSTASIS; 2003
Institución organizadora:
THE INTERNATIONAL SOCIETY ON THROMBOSIS AND HAEMOSTASIS
Resumen:
Infusion of DDAVP induces the release of unusually large VWFmultimers, increasing the plasma concentration of VWF. The ADAMTS13 cleaves these unusually large VWF multimers in vivo and larger VWF forms in vitro. To evaluate the relation between changes in plasma VWF and protease levels, we measured ADAMTS13 and VWF-related parameters in patients with type 1 von Willebrand disease (VWF:RCo = [37-49%]) before and after infusing 0.3 mg kg-1 DDAVP. The VWF-related parameters in the patients increased 60 min after the infusion by 3.4 fold for VWF:Ag and 2.7 fold for VWF:RCo. Sonication of plasma VWF degrades the largest multimeric forms. To exclude the possibility that the high endogenous VWF forms of larger molecular weight (highly reactive with collagen) might interfere with the assay, all plasma samples were sonicated (20 kHz during 10 min at room temperature in a circulating bath). ADAMTS13 activity was measured according to Furlan method modified by dialyzing the reaction mixture in dialysis tubing against urea. Measuring residual collagen-binding activity assessed the extent of the degradation of exogenous purified VWF. The results are presented as means (M) ± standard deviation (SD) of the activity of normal pooled human plasma. The results of ADAMTS13 activity of non sonicated plasma samples vs. sonicated samples both before infusion of DDAVP were: 73 ± 11% vs. 83 ± 16% (n = 9; P = 0.118) and results from nonsonicated vs. sonicated samples after DDAVP infusion were: 59 ± 10% vs. 78 ± 18% (n = 9; P = 0.006). Sonication does not alter ADAMTS13 activity, as we did not find significant differences between samples before infusion of DDAVP, sonicated or not. However there were significant differences between before (73 ± 11%) and after DDAVP (59 ± 10%) in non sonicated samples (n = 9; P = 0.012). We concluded that the diminished ADAMTS13 activity found in nonsonicated samples after infusion of DDAVP, does not represent an 'in vivo' consumption of the enzyme. So, before measuring ADAMTS13 activity, it would be necessary to eliminate completely endogenous VWF in any plasma sample with high VWF levels.