Crucial role for the VWF A1 domain in binding to type IV collagen.

Von Willebrand factor (VWF) contains binding sites for platelets and for vascular collagens to facilitate clot formation at sites of injury. Although previous work has shown that VWF can bind type IV collagen (collagen 4), little characterization of this interaction has been performed. We examined the binding of VWF to collagen 4 in vitro and extended this characterization to a murine model of defective VWF-collagen 4 interactions. The interactions of VWF and collagen 4 were further studied using plasma samples from a large study of both healthy controls and subjects with different types of von Willebrand disease (VWD). Our results show that collagen 4 appears to bind VWF exclusively via the VWF A1 domain, and that specific sequence variations identified through VWF patient samples and through site-directed mutagenesis in the VWF A1 domain can decrease or abrogate this interaction. In addition, VWF-dependent platelet binding to collagen 4 under flow conditions requires an intact VWF A1 domain. We observed that decreased binding to collagen 4 was associated with select VWF A1 domain sequence variations in type 1 and type 2M VWD. This suggests an additional mechanism through which VWF variants may alter hemostasis.

Impact of an External Ventricular Drain Placement and Handling Protocol on Infection Rates: A Meta-Analysis and Single Institution Experience.

BACKGROUND: Numerous studies have examined the impact of initiating an external ventricular drain (EVD) placement and handling protocol on the infection rate dating back to the early 2000s. METHODS: We report a quantitative systematic review of the published literature, described our own protocol (including a mandatory checklist), and present our single institution experience. Search terms "external ventricular drain protocol" or "external ventricular drain placement protocol" or "preventing infections in external ventricular drains" or "external ventricular drain infections" were entered into standard search engines in a systematic fashion. Articles were reviewed and graded independently for class of evidence. There were 10 relevant class IV articles and no discrepancies among article ratings (i.e., κ = 1). The published evidence was reviewed and evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria. RESULTS: Our meta-analysis revealed a statistically significant drop in rates of EVD infection after initiation of the protocol, although the overall quality of the body of evidence according to the GRADE criteria was "very poor". Preimplementation and postimplementation infection rates were collected and analyzed in combination with the results from our literature review. The EVD infection rate in our institution was 12% in the 8 months before protocol initiation (January 2015 to August 2015), and dropped to 0% in the 7 months after initiation. CONCLUSIONS: Although the quality of the literature supporting EVD placement protocols is poor, all published studies show a consistent and substantial benefit, and this effect was recapitulated in our own meta-analysis-based prospective EVD protocol experience.