Major haemorrhage related to surgery in patients with type 1 and possible type 1 von Willebrand disease.

Patients with von Willebrand disease (VWD) frequently bleed under a challenge. The aim of our study was to identify predictive markers of perioperative major haemorrhage in type 1 (VWF:RCo = 15-30 IU dl(-1)) and possible type 1 (VWF:RCo = 31-49 IU dl(-1)) VWD patients. We recorded perioperative bleeding complications previous to diagnosis and laboratory parameters in 311 patients with 498 surgical procedures.

von Willebrand factor-cleaving protease (ADAMTS13) activity in normal non-pregnant women, pregnant and post-delivery women.

ADAMTS13 dysfunction has been involved in the pathogenesis of Thrombotic Thrombocytopenic Purpura. This disorder occurs more frequently in women and, in 13% of them, is associated with pregnancy. However, there is little information on the protease behaviour in normal pregnancy.

Control of von Willebrand factor multimer size by a fibronectin-related substance.

Fraction (F) II and FIII obtained by heparin-Sepharose after digestion of partially purified fibronectin (FN) with cathepsin D and F3, obtained like FIII but from untreated FN, exerted activity (arFN) on unfolded purified von Willebrand factor (vWF) that controls vWF multimer size. Our aim was to evaluate the arFN of F from commercial FN, commercial 30 kDa (with heparin affinity), 45 kDa (gelatin affinity) and 70 kDa FN fragments (gelatin and heparin affinity) and whole FN. The arFN was detected in FII, FIII, F2, F3, 30 kDa, 45 kDa and 70 kDa fragments.

Von Willebrand factor cleaving protease activity in the physiopathology of microangiopathic disorders.

The von Willebrand factor cleaving protease (VWFCP) modulates the von Willebrand factor (VWF) multimeric size in normal plasma. VWFCP activity levels are decreased in different physiological and pathologic situations. Different techniques have been developed to unfold the purified VWF (perfusion at high shear rate, dialysis against urea in nitrocellulose filters), to detect the VWFCP activity on it (multimeric analysis of VWF, collagen binding to VWF assay) and to use the patient plasma both as the source of the enzyme and substrate.