Portal biliopathy(PB) is defined as the presence of biliary abnormalities in patients with non-cirrhotic/nonneoplastic extrahepatic portal vein obstruction(EHPVO) and portal cavernoma(PC). The pathogenesis of PB is du...Portal biliopathy(PB) is defined as the presence of biliary abnormalities in patients with non-cirrhotic/nonneoplastic extrahepatic portal vein obstruction(EHPVO) and portal cavernoma(PC). The pathogenesis of PB is due to ab extrinseco compression of bile ducts by PC and/or to ischemic damage secondary to an altered biliary vascularization in EHPVO and PC. Although asymptomatic biliary abnormalities can be frequently seen by magnetic resonance cholangiopancreatography in patients with PC(77%-100%), only a part of these(5%-38%) are symptomatic. Clinical presentation includes jaundice, cholangitis, cholecystitis, abdominal pain, and cholelithiasis. In this subset of patients is required a specific treatment. Different therapeutic approaches aimed to diminish portal hypertension and treat biliary strictures are available. In order to decompress PC, surgical porto-systemic shunt or transjugular intrahepatic porto-systemic shunt can be performed, and treatment on the biliary stenosis includes endoscopic(Endoscopic retrograde cholangiopancreatography with endoscopic sphincterotomy, balloon dilation, stone extraction, stent placement) and surgical(bilioenteric anastomosis, cholecystectomy) approaches. Definitive treatment of PB often requires multiple and combined interventions both on vascular and biliary system. Liver transplantation can be considered in patients with secondary biliary cirrhosis, recurrent cholangitis or unsuccessful control of portal hypertension.展开更多
For video streaming over lossy channels, intra refresh can mitigate the error-propagation effect caused by packet losses Besides some intra-mode macroblocks （MBs） generated by the ＂Lagrangian rate-distortion＂ or ...For video streaming over lossy channels, intra refresh can mitigate the error-propagation effect caused by packet losses Besides some intra-mode macroblocks （MBs） generated by the ＂Lagrangian rate-distortion＂ or ＂Sum of absolute difference＂ mode decision, the encoder or transcoder possibly needs to increase some ＂forced＂ intra-mode MBs for robust video streaming. Based on the error-propagation analysis in a group of pictures （GOP）, we propose an unequal Forced-Intra-Refresh （FIR） scheme to improve packet loss resilience of video streaming. According to a GOP-level error-propagation model, the proposed unequal FIR scheme can optimally increase the unequal number of forced intra-mode MBs for different frames in a GOP. Simulation results showed that the proposed scheme can effectively enhance the robustness of video streaming under different channel conditions, and achieve about 0. 1-0.9 dB gains over the average FIR scheme in H.264/AVC tools.展开更多
Endothelial cells form the internal barrier between circulating blood and the vessel wall.They regulate arterial activity and mediate pathological reactions to vascular injuries such as atherosclerosis and balloon ang...Endothelial cells form the internal barrier between circulating blood and the vessel wall.They regulate arterial activity and mediate pathological reactions to vascular injuries such as atherosclerosis and balloon angioplasty.The development and differentiation of endothelial cells is a complex and coordinated process involving multiple levels of signaling and transcriptional and post-transcriptional regulation.Elucidating the mechanism of endothelial differentiation will not only enhance our understanding of vascular disease pathogenesis,but also facilitate our ability to produce vessels cells from pluripotent stem cells for regeneration purposes.In this review,we discuss the current understanding of how stem cells differentiate into endothelial cells at the level of signaling,transcription and microRNA regulation.展开更多
文摘Portal biliopathy(PB) is defined as the presence of biliary abnormalities in patients with non-cirrhotic/nonneoplastic extrahepatic portal vein obstruction(EHPVO) and portal cavernoma(PC). The pathogenesis of PB is due to ab extrinseco compression of bile ducts by PC and/or to ischemic damage secondary to an altered biliary vascularization in EHPVO and PC. Although asymptomatic biliary abnormalities can be frequently seen by magnetic resonance cholangiopancreatography in patients with PC(77%-100%), only a part of these(5%-38%) are symptomatic. Clinical presentation includes jaundice, cholangitis, cholecystitis, abdominal pain, and cholelithiasis. In this subset of patients is required a specific treatment. Different therapeutic approaches aimed to diminish portal hypertension and treat biliary strictures are available. In order to decompress PC, surgical porto-systemic shunt or transjugular intrahepatic porto-systemic shunt can be performed, and treatment on the biliary stenosis includes endoscopic(Endoscopic retrograde cholangiopancreatography with endoscopic sphincterotomy, balloon dilation, stone extraction, stent placement) and surgical(bilioenteric anastomosis, cholecystectomy) approaches. Definitive treatment of PB often requires multiple and combined interventions both on vascular and biliary system. Liver transplantation can be considered in patients with secondary biliary cirrhosis, recurrent cholangitis or unsuccessful control of portal hypertension.
基金Project (No. 60332030) supported by the National Natural ScienceFoundation of China
文摘For video streaming over lossy channels, intra refresh can mitigate the error-propagation effect caused by packet losses Besides some intra-mode macroblocks （MBs） generated by the ＂Lagrangian rate-distortion＂ or ＂Sum of absolute difference＂ mode decision, the encoder or transcoder possibly needs to increase some ＂forced＂ intra-mode MBs for robust video streaming. Based on the error-propagation analysis in a group of pictures （GOP）, we propose an unequal Forced-Intra-Refresh （FIR） scheme to improve packet loss resilience of video streaming. According to a GOP-level error-propagation model, the proposed unequal FIR scheme can optimally increase the unequal number of forced intra-mode MBs for different frames in a GOP. Simulation results showed that the proposed scheme can effectively enhance the robustness of video streaming under different channel conditions, and achieve about 0. 1-0.9 dB gains over the average FIR scheme in H.264/AVC tools.
基金supported by the National Natural Science Foundation of China(91339102,81270001,81270180)the Zhejiang Provincial Natural Science Foundation(LR14H020001)
文摘Endothelial cells form the internal barrier between circulating blood and the vessel wall.They regulate arterial activity and mediate pathological reactions to vascular injuries such as atherosclerosis and balloon angioplasty.The development and differentiation of endothelial cells is a complex and coordinated process involving multiple levels of signaling and transcriptional and post-transcriptional regulation.Elucidating the mechanism of endothelial differentiation will not only enhance our understanding of vascular disease pathogenesis,but also facilitate our ability to produce vessels cells from pluripotent stem cells for regeneration purposes.In this review,we discuss the current understanding of how stem cells differentiate into endothelial cells at the level of signaling,transcription and microRNA regulation.
