ABSTRACT
A 22-year-old Japanese woman was found to have severe esophageal varices and then suffered from hepatic encephalopathy. She was diagnosed with Budd-Chiari syndrome (BCS) due to hepatic vein (HV) thrombosis accompanied by portal vein thrombosis without inferior vena cava (IVC) obstruction. Latent myeloproliferative neoplasm (MPN) lacking the JAK2-V617F mutation was considered to be the underlying disease. Liver transplantation was strikingly effective for treating the clinical symptoms attributable to portal hypertension. Although thrombosis of the internal jugular vein occurred due to thrombocythemia, which manifested after transplantation despite anticoagulation therapy with warfarin, the thrombus immediately disappeared with the addition of aspirin. Neither thrombosis nor BCS has recurred in more than 4 years since the amelioration of the last thrombotic event, and post-transplant immunosuppression with tacrolimus has not accelerated the progression of MPN. In Japan, IVC obstruction, which was a predominant type of BCS, is suggested to have decreased in incidence with recent improvements in hygiene. The precise diagnosis of BCS and causative underlying diseases should be made with attention to the current trend of the disease spectrum, which fluctuates with environmental sanitation levels. Because the stepwise strategy, including liver transplantation, has been proven effective for patients with pure HV obstruction in Western countries, this strategy should also be validated for utilization in Japan and in developing countries where HV obstruction potentially predominates.
ABSTRACT
Drebrin-A is an actin-binding protein localized in the dendritic spines of mature neurons, and has been suggested to affect spine morphology [K. Hayashi, T. Shirao, Change in the shape of dendritic spines caused by overexpression of drebrin in cultured cortical neurons, J. Neurosci. 19 (1999) 3918-3925]. However, no biochemical analysis of drebrin-A has yet been reported. In this study, we purified drebrin-A using a bacterial expression system, and characterized it in vitro. Drebrin-A bound to actin filaments with a stoichiometry of one drebrin molecule to 5-6 actin molecules. Furthermore, drebrin-A decreased the Mg-ATPase activity of myosin V. In vitro motility assay revealed that the attachment of F-actin to glass surface coated with myosin-V was decreased by drebrin-A, but once F-actin attached to the surface, the sliding speed of F-actin was unaffected by the presence of drebrin A. These findings suggest that drebrin-A may affect spine dynamics, vesicle transport, and other myosin-V-driven motility in neurons through attenuating the interaction between actin and myosin-V.
