ABSTRACT
Most Neurosurgical Service patients at our hospital receive venous thromboembolism prophylaxis. In 1995-96, the rate of clinically overt venous thromboembolism was 3.7% among patients undergoing neurosurgery. However, rates were much higher when craniotomy was undertaken for brain tumor. Of 497 who underwent craniotomy for primary (429) or metastatic (68) brain tumor, 47 (9.5%) developed clinically overt venous thromboembolism: 7.5% after primary brain tumor resection and 19% after craniotomy for metastatic cancer. The high rate of venous thromboembolism in craniotomy patients with brain tumor warrants study of alternative measures for preventing thrombus, such as prophylaxis with low molecular weight heparin.
Subject(s)
Brain Neoplasms/surgery , Postoperative Complications , Venous Thrombosis/etiology , Female , Fibrinolytic Agents/administration & dosage , Heparin, Low-Molecular-Weight/administration & dosage , Humans , Male , Middle Aged , Postoperative Complications/prevention & control , Venous Thrombosis/prevention & controlABSTRACT
von Willebrand factor (vWF) is a multimeric plasma protein that mediates platelet adhesion to exposed subendothelium at sites of vascular injury. The A3 domain of vWF (vWF-A3) forms the principal binding site for collagens type I and III. We report here the crystal structure of the vWF-A3 domain at 2.2-A resolution. As expected, the structure is similar to the integrin I domain but with several novel features. Sequence alignments had suggested that the domain contained an integrin metal ion-dependent adhesion site (MIDAS) motif, but the crystal structure shows that the motif is modified and that no metal ion is bound. We have introduced mutations into the vestigial MIDAS motif and report that, unlike the I domain of integrin alpha2beta1, vWF-A3 continues to bind collagen after disruption of the motif. We conclude that collagen recognition by vWF-A3 occurs by a mechanism different from that of the integrin alpha2beta1.
