Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the ...Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimization of the macroscopic holes silk^(+) tNGC approach containing macroscopic holes might result in improved grafting technology suitable for future clinical use.展开更多
系统级动态功耗管理(Dynamic Power Management,DPM)策略根据系统状态和负载,动态地调整系统配置,从而能够有效降低系统功耗。传统的DPM策略仅从设备的角度考察工作负载状况,忽略了工作负载的应用特征。本文从任务的角度分析负载,提出...系统级动态功耗管理(Dynamic Power Management,DPM)策略根据系统状态和负载,动态地调整系统配置,从而能够有效降低系统功耗。传统的DPM策略仅从设备的角度考察工作负载状况,忽略了工作负载的应用特征。本文从任务的角度分析负载,提出新颖的多请求源(Multiple Service Requesters,MSR)系统级功耗管理的模型,以及基于该模型的自适应超时策略(Multiple-Service-Requester-Based Timeout Policy,MSRBTP)。实验表明,与传统DPM策略相比较,在非平稳的应用环境下,MSRBTP策略具有更好更稳定的节能效果。展开更多
基金supported by the Lorenz B?hler Fonds,#2/19 (obtained by the Neuroregeneration Group,Ludwig Boltzmann Institute for Traumatology)the City of Vienna project ImmunTissue,MA23#30-11 (obtained by the Department Life Science Engineering,University of Applied Sciences Technikum Wien)。
文摘Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimization of the macroscopic holes silk^(+) tNGC approach containing macroscopic holes might result in improved grafting technology suitable for future clinical use.
文摘系统级动态功耗管理(Dynamic Power Management,DPM)策略根据系统状态和负载,动态地调整系统配置,从而能够有效降低系统功耗。传统的DPM策略仅从设备的角度考察工作负载状况,忽略了工作负载的应用特征。本文从任务的角度分析负载,提出新颖的多请求源(Multiple Service Requesters,MSR)系统级功耗管理的模型,以及基于该模型的自适应超时策略(Multiple-Service-Requester-Based Timeout Policy,MSRBTP)。实验表明,与传统DPM策略相比较,在非平稳的应用环境下,MSRBTP策略具有更好更稳定的节能效果。
