1,814 research outputs found
Rab13 Is Involved in the Entry Step of Hepatitis C Virus Infection
Membrane transport probably participates in the lifecycle of hepatitis C virus (HCV). Rab proteins are essential host factors for HCV RNA replication, but these proteins’ roles in other steps of the HCV lifecycle are not clear. The tight junction (TJ) plays a key role in HCV infection. Rab13 regulates the endocytic recycling of the TJ-associated proteins. Here we investigated whether Rab13 is involved in the HCV entry step. We used HuH-7-derived RSc cells and Li23-derived D7 cells. To evaluate the effect of Rab13 in HCV infection, we transfected the cells with siRNA targeting Rab13 before HCV infection. The down-regulation of Rab13 inhibited HCV infection. The D7 cells had showed a greater inhibitory effect against HCV infection compared to that in the RSc cells by Rab13 knockdown. Next, to evaluate the effect of Rab13 after infection, we inoculated the cells with HCV before transfection of the siRNA. The down-regulation of Rab13 did not show any effects after HCV infection. We further examined whether Rab13 would influence HCV RNA replication by using HCV replicon-harboring cells. The results revealed that Rab13 did not affect the step of HCV RNA replication. These results suggest that Rab13 plays an important role in the step of HCV entry
Effect of the curvature and the {\beta} parameter on the nonlinear dynamics of a drift tearing magnetic island
We present numerical simulation studies of 2D reduced MHD equations
investigating the impact of the electronic \beta parameter and of curvature
effects on the nonlinear evolution of drift tearing islands. We observe a
bifurcation phenomenon that leads to an amplification of the pressure energy,
the generation of E \times B poloidal flow and a nonlinear diamagnetic drift
that affects the rotation of the magnetic island. These dynamical modifications
arise due to quasilinear effects that generate a zonal flow at the onset point
of the bifurcation. Our simulations show that the transition point is
influenced by the \beta parameter such that the pressure gradient through a
curvature effect strongly stabilizes the transition. Regarding the modified
rotation of the island, a model for the frequency is derived in order to study
its origin and the effect of the \beta parameter. It appears that after the
transition, an E \times B poloidal flow as well as a nonlinear diamagnetic
drift are generated due to an amplification of the stresses by pressure
effects
Annexin A1 Negatively Regulates Viral RNA Replication of Hepatitis C Virus
Persistent infection with hepatitis C virus (HCV) often causes chronic hepatitis, and then shows a high rate of progression to liver cirrhosis and hepatocellular carcinoma. To clarify the mechanism of the persistent HCV infection is considered to be important for the discovery of new target(s) for the development of anti-HCV strategies. In the present study, we found that the expression level of annexin A1 (ANXA1) in human hepatoma cell line Li23-derived D7 cells was remarkably lower than that in parental Li23 cells, whereas the susceptibility of D7 cells to HCV infection was much higher than that of Li23 cells. Therefore, we hypothesized that ANXA1 negatively regulates persistent HCV infection through the inhibition of viral RNA replication. The results revealed that HCV production was significantly inhibited without a concomitant reduction in the amount of lipid droplets in the D7 cells stably expressing exogenous ANXA1. Further, we demonstrated that ANXA1 negatively regulated the step of viral RNA replication rather than that of viral entry in human hepatocytes. These results suggest that ANXA1 would be a novel target for the development of anti-HCV strategies
The DNA damage sensors ataxia-telangiectasia mutated kinase and checkpoint kinase 2 are required for hepatitis C virus RNA replication
Liquefaction Potential Evaluation: Energy-Based Method Compared to Stress-Based Method
A data set of undrained cyclic triaxial test with parametrically changing relative density and fines content is reviewed and interpreted in the scope of energy. It is found that the strain amplitude or pore-pressure buildup during cyclic loading is uniquely related to the energy dissipated in soil specimens. This further indicates that a RL (cyclic stress ratio)-Nc (number of cycles) line corresponding to specific soil strain represents a line of equal dissipated energy. An energy-based method (EBM) is proposed in which liquefaction potential can be evaluated by comparing the dissipated energy with upward seismic wave energy with no regard to stress intensity and the number of cycles. EBM developed here is applied to a hypothetical sand deposit shaken by a recorded seismic motion of the earthquake magnitude M=9.0 to compare with a conventional stress-based method (SBM) using the same seismic motion. The two results have similarities and differences, and the similarity tends to be greater, if the effect of M=9.0 is considered in SBM
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