AIM To investigate whether bone marrow mesenchymal stem cells (BMMSCs) modified with the HO-1 and CXCR3 genes can augment the inhibitory effect of BMMSCs on small bowel transplant rejection. METHODS Lewis rat BMMSCs w...AIM To investigate whether bone marrow mesenchymal stem cells (BMMSCs) modified with the HO-1 and CXCR3 genes can augment the inhibitory effect of BMMSCs on small bowel transplant rejection. METHODS Lewis rat BMMSCs were cultured in vitro. Third-passage BMMSCs were transduced with the CXCR3 / HO-1 genes or the HO-1 gene alone. The rats were divided into six groups and rats in the experimental group were pretreated with BMMSCs 7 d prior to small bowel transplant. Six time points (instant, 1 d, 3 d, 7 d, 10 d, and 14 d) (n = 6) were chosen for each group. Hematoxylin-eosin staining was used to observe pathologic rejection, while immunohistochemistry and Western blot were used to detect protein expression. Flow cytometry was used to detect T lymphocytes and enzyme linked immunosorbent assay was used to detect cytokines. RESULTS The median survival time of BMMSCs from the CXCR3/HO-1 modified group (53 d) was significantly longer than that of the HO-1 modified BMMSCs group (39 d), the BMMSCs group (26 d), and the NS group (control group) (16 d) (P < 0.05). Compared with BMMSCs from the HO-1 modified BMMSCs, BMMSCs, and NS groups, rejection of the small bowel in the CXCR3 / HO-1 modified group was significantly reduced, while the weight of transplant recipients was also significantly decreased (P < 0.05). Furthermore, IL-2, IL-6, IL-17, IFN-gamma, and TNF-alpha levels were significantly decreased and the levels of IL-10 and TGF-beta were significantly increased (P < 0.05). CONCLUSION BMMSCs modified with the CXCR3 and HO-1 genes can abrogate the rejection of transplanted small bowel more effectively and significantly increase the survival time of rats that receive a small bowel transplant.展开更多
LDoS （Low-rate Denial of Service） attack, exploiting the flaws in the congestion avoidance mechanism of TCP protocol,is periodic, stealthy, and with high efficiency. Since BGP uses TCP as a transport protocol, it is...LDoS （Low-rate Denial of Service） attack, exploiting the flaws in the congestion avoidance mechanism of TCP protocol,is periodic, stealthy, and with high efficiency. Since BGP uses TCP as a transport protocol, it is subject to LDoS attacks as well. LDoS attacks can cause table reset, route flapping of BGP protocol. A deliberately constructed distributed low-rate DOS attacks can even generate surge of updates throughout the Internet. In this paper, we investigate the promotion of attack efficiency of this novel attack, and then propose an attack model to simulate the LDoS attack. Experiments prove that this attack model can exponentially lower the attack costs and improve the attack effect.展开更多
In frequency domain,the power spectrum of Low-rate denial of service(LDoS) attacks is totally spread into the spectrum of normal traffic.It is a challenging task to detect and filter LDoS attack flows from the normal ...In frequency domain,the power spectrum of Low-rate denial of service(LDoS) attacks is totally spread into the spectrum of normal traffic.It is a challenging task to detect and filter LDoS attack flows from the normal traffic.Based on the analysis of LDoS attack flows and legitimate TCP traffic in time and frequency domains,the periodicity of the TCP traffic and LDoS attack flows is explored to facilitate the research of network traffic processing.Hence,an approach of LDoS attack flow filtering based on frequency spectrum analysis is proposed.In this approach,the TCP traffic and LDoS attack flows are transformed from the time domain into the frequency domain.Then the round-trip time(RTT) is estimated by using frequency domain search method.Analysis of amplitude spectrum shows that TCP traffic energy is mainly concentrated on the points of n/RTT.Therefore,a comb filter using infinite impulse response(IIR) filter is designed to filter out the LDoS attack flows in frequency domain,while most legitimate TCP traffic energy at the points of n/RTT are pass through.Experimental results show that the maximum pass rate for legitimate TCP traffic reaches 92.55%,while the maximum filtration rate of LDoS attack flows reaches 81.36%.The proposed approach can effectively filter the LDoS attack flows while less impact on the legitimate TCP traffic.展开更多
AIMTo investigated the feasibility of using sinusoidal endotheliitis (SE) as a histological marker for liver allograft rejection.METHODSWe compared the histological features of 88 liver allograft biopsies with acute c...AIMTo investigated the feasibility of using sinusoidal endotheliitis (SE) as a histological marker for liver allograft rejection.METHODSWe compared the histological features of 88 liver allograft biopsies with acute cellular rejection (ACR) and 59 cases with no evidence of ACR. SE was scored as: (1) focal linear lifting up of the endothelial cells by lymphocytes with no obvious damage to adjacent hepatocytes; (2) focal disruption of the endothelial lining by a cluster of subendothelial lymphocytes (a group of > 3 lymphocytes); and (3) severe confluent endotheliitis with hemorrhage and adjacent hepatocyte loss.RESULTSThe sensitivity and specificity of SE was 81% and 85%, respectively. Using SE as the only parameter, the positive predictive value for ACR (PPV) was 0.89, whereas the negative predictive value for ACR (NPV) was 0.75. The correlation between RAI and SE was moderate (R = 0.44, P < 0.001) (Figure 3A), whereas it became strong (R = 0.65, P < 0.001) when correlating SE with the venous endotheliitis activity index only.CONCLUSIONOur data suggest that SE scoring could be a reliable and reproducible supplemental parameter to the existing Banff schema for diagnosing acute liver allograft rejection.展开更多
基金Supported by The National Natural Science Foundation of China,No.81670574,No.81441022 and No.81270528The Natural Science Foundation of Tianjin,China,No.08JCYBJC08400,No.11JCZDJC27800 and No.12JCZDJC25200The Technology Foundation of the Health Bureau of Tianjin,China,No.2011KY11
文摘AIM To investigate whether bone marrow mesenchymal stem cells (BMMSCs) modified with the HO-1 and CXCR3 genes can augment the inhibitory effect of BMMSCs on small bowel transplant rejection. METHODS Lewis rat BMMSCs were cultured in vitro. Third-passage BMMSCs were transduced with the CXCR3 / HO-1 genes or the HO-1 gene alone. The rats were divided into six groups and rats in the experimental group were pretreated with BMMSCs 7 d prior to small bowel transplant. Six time points (instant, 1 d, 3 d, 7 d, 10 d, and 14 d) (n = 6) were chosen for each group. Hematoxylin-eosin staining was used to observe pathologic rejection, while immunohistochemistry and Western blot were used to detect protein expression. Flow cytometry was used to detect T lymphocytes and enzyme linked immunosorbent assay was used to detect cytokines. RESULTS The median survival time of BMMSCs from the CXCR3/HO-1 modified group (53 d) was significantly longer than that of the HO-1 modified BMMSCs group (39 d), the BMMSCs group (26 d), and the NS group (control group) (16 d) (P < 0.05). Compared with BMMSCs from the HO-1 modified BMMSCs, BMMSCs, and NS groups, rejection of the small bowel in the CXCR3 / HO-1 modified group was significantly reduced, while the weight of transplant recipients was also significantly decreased (P < 0.05). Furthermore, IL-2, IL-6, IL-17, IFN-gamma, and TNF-alpha levels were significantly decreased and the levels of IL-10 and TGF-beta were significantly increased (P < 0.05). CONCLUSION BMMSCs modified with the CXCR3 and HO-1 genes can abrogate the rejection of transplanted small bowel more effectively and significantly increase the survival time of rats that receive a small bowel transplant.
文摘LDoS （Low-rate Denial of Service） attack, exploiting the flaws in the congestion avoidance mechanism of TCP protocol,is periodic, stealthy, and with high efficiency. Since BGP uses TCP as a transport protocol, it is subject to LDoS attacks as well. LDoS attacks can cause table reset, route flapping of BGP protocol. A deliberately constructed distributed low-rate DOS attacks can even generate surge of updates throughout the Internet. In this paper, we investigate the promotion of attack efficiency of this novel attack, and then propose an attack model to simulate the LDoS attack. Experiments prove that this attack model can exponentially lower the attack costs and improve the attack effect.
基金supported in part by the National Natural Science Foundation under grant No.U1533107the Major Program of Natural Science Foundation of Tianjin under grant No.17JCZDJC30900+1 种基金the Fundamental Research Funds for the Central Universities of CAUC under grant No.3122016D003the graduate program of curriculum development project of Civil Aviation University of China(2050070515)
文摘In frequency domain,the power spectrum of Low-rate denial of service(LDoS) attacks is totally spread into the spectrum of normal traffic.It is a challenging task to detect and filter LDoS attack flows from the normal traffic.Based on the analysis of LDoS attack flows and legitimate TCP traffic in time and frequency domains,the periodicity of the TCP traffic and LDoS attack flows is explored to facilitate the research of network traffic processing.Hence,an approach of LDoS attack flow filtering based on frequency spectrum analysis is proposed.In this approach,the TCP traffic and LDoS attack flows are transformed from the time domain into the frequency domain.Then the round-trip time(RTT) is estimated by using frequency domain search method.Analysis of amplitude spectrum shows that TCP traffic energy is mainly concentrated on the points of n/RTT.Therefore,a comb filter using infinite impulse response(IIR) filter is designed to filter out the LDoS attack flows in frequency domain,while most legitimate TCP traffic energy at the points of n/RTT are pass through.Experimental results show that the maximum pass rate for legitimate TCP traffic reaches 92.55%,while the maximum filtration rate of LDoS attack flows reaches 81.36%.The proposed approach can effectively filter the LDoS attack flows while less impact on the legitimate TCP traffic.
文摘AIMTo investigated the feasibility of using sinusoidal endotheliitis (SE) as a histological marker for liver allograft rejection.METHODSWe compared the histological features of 88 liver allograft biopsies with acute cellular rejection (ACR) and 59 cases with no evidence of ACR. SE was scored as: (1) focal linear lifting up of the endothelial cells by lymphocytes with no obvious damage to adjacent hepatocytes; (2) focal disruption of the endothelial lining by a cluster of subendothelial lymphocytes (a group of > 3 lymphocytes); and (3) severe confluent endotheliitis with hemorrhage and adjacent hepatocyte loss.RESULTSThe sensitivity and specificity of SE was 81% and 85%, respectively. Using SE as the only parameter, the positive predictive value for ACR (PPV) was 0.89, whereas the negative predictive value for ACR (NPV) was 0.75. The correlation between RAI and SE was moderate (R = 0.44, P < 0.001) (Figure 3A), whereas it became strong (R = 0.65, P < 0.001) when correlating SE with the venous endotheliitis activity index only.CONCLUSIONOur data suggest that SE scoring could be a reliable and reproducible supplemental parameter to the existing Banff schema for diagnosing acute liver allograft rejection.
