Communication security is a critical aspect of QoS provisioning in wireless mesh network （WMN）. Because of the inherent characteristics of WMN, conventional security mechanisms cannot be applied. In order to guarant...Communication security is a critical aspect of QoS provisioning in wireless mesh network （WMN）. Because of the inherent characteristics of WMN, conventional security mechanisms cannot be applied. In order to guarantee the communication security, a novel communication security mechanism is proposed. The mechanism uses a communication encryption scheme to encrypt data packets and employs a risk avoidance scheme to avoid the malicious nodes during communications. Simulation results indicate that the mechanism is able to provide secure communication effectively and reduce the damage of attacks through multiple paths.展开更多
Aim Aging is an independent risk factor for heart disease, however the effective intervention has not been found so far. Bone marrow mesenchymal stem cells （BMSCs） have been shown to offer a wide variety of cel- l...Aim Aging is an independent risk factor for heart disease, however the effective intervention has not been found so far. Bone marrow mesenchymal stem cells （BMSCs） have been shown to offer a wide variety of cel- lular functions including the protective effects on damaged hearts. Here we investigated the antiaging properties of BMSCs and the underlying mechanism in a cellular model of cardiomyocyte senescence and a rat model of aging hearts. Methods In vitro study, neonatal rat ventricular cells （NRVCs） and BMSCs were cocultured in the same dish with a semipermeable membrane to separate the two populations. In vivo, the BMSCs were injected into the rat hearts to observe their antiaging effects. The expression of β-galactosidase and aging-related proteins, and the lev- els of oxidative stress were determined in vivo and in vitro. The heart function was measured by the High-Resolution Imaging System. Results Monocultured NRVCs displayed the senescence-associated phenotypes, characterized by an increase in the number of β-galaetosidase-positive cells and decreases in the degradation and disappearance of cellular organelles in a time-dependent manner. The levels of reactive oxygen species and malondialdehyde were el- evated, whereas the activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase were de- creased, along with upregulation of p53, p21cipl/wafl and p16INK4a in the aging eardiomyoeytes. These deleterious alterations were abrogated in aging NRVCs cocultured with BMSCs. Qualitatively, the same senescent phenotypes were consistently observed in aging rat hearts. Notably, BMSC transplantation significantly prevented these detri- mental alterations and improved the impaired cardiac function in the aging rats. Conclusions BMSCs possess strong antiseneseence action on the aging NRVCs and hearts and can improve cardiac function after transplantation in aging rats. The present study, therefore, provides an alternative approach for the treatment of heart failure in the elderly population.展开更多
基金This project was supported by the National Natural Science Foundation of China (60573129).
文摘Communication security is a critical aspect of QoS provisioning in wireless mesh network （WMN）. Because of the inherent characteristics of WMN, conventional security mechanisms cannot be applied. In order to guarantee the communication security, a novel communication security mechanism is proposed. The mechanism uses a communication encryption scheme to encrypt data packets and employs a risk avoidance scheme to avoid the malicious nodes during communications. Simulation results indicate that the mechanism is able to provide secure communication effectively and reduce the damage of attacks through multiple paths.
文摘Aim Aging is an independent risk factor for heart disease, however the effective intervention has not been found so far. Bone marrow mesenchymal stem cells （BMSCs） have been shown to offer a wide variety of cel- lular functions including the protective effects on damaged hearts. Here we investigated the antiaging properties of BMSCs and the underlying mechanism in a cellular model of cardiomyocyte senescence and a rat model of aging hearts. Methods In vitro study, neonatal rat ventricular cells （NRVCs） and BMSCs were cocultured in the same dish with a semipermeable membrane to separate the two populations. In vivo, the BMSCs were injected into the rat hearts to observe their antiaging effects. The expression of β-galactosidase and aging-related proteins, and the lev- els of oxidative stress were determined in vivo and in vitro. The heart function was measured by the High-Resolution Imaging System. Results Monocultured NRVCs displayed the senescence-associated phenotypes, characterized by an increase in the number of β-galaetosidase-positive cells and decreases in the degradation and disappearance of cellular organelles in a time-dependent manner. The levels of reactive oxygen species and malondialdehyde were el- evated, whereas the activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase were de- creased, along with upregulation of p53, p21cipl/wafl and p16INK4a in the aging eardiomyoeytes. These deleterious alterations were abrogated in aging NRVCs cocultured with BMSCs. Qualitatively, the same senescent phenotypes were consistently observed in aging rat hearts. Notably, BMSC transplantation significantly prevented these detri- mental alterations and improved the impaired cardiac function in the aging rats. Conclusions BMSCs possess strong antiseneseence action on the aging NRVCs and hearts and can improve cardiac function after transplantation in aging rats. The present study, therefore, provides an alternative approach for the treatment of heart failure in the elderly population.
