Protective Effect of Purple Sweet Potato (Ipomoea batatas Linn, Convolvulaceae) on Neuroinflammatory Responses in Lipopolysaccharide-Stimulated Microglial Cells

Purpose: To evaluate the protective effects of purple sweet potato (Ipomoea batatas Linn, Convolvulaceae) extract (IBE) in stimulated BV-2 microglial cells and its anti-oxidant properties.Methods: Cell viability assessment was performed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide (MTT) assay. Lipopolysaccharide (LPS) was used to activate BV-2 microglia. Nitric oxide (NO) levels were measured using Griess assay. Inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 expressional levels were measured by Western blot analysis. Tumor necrosis factor-alpha (TNF-α) production was evaluated by enzyme-linked immunosorbent assay (ELISA). Antioxidantproperties were evaluated by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging assay.Results: LPS-activated excessive release of NO in BV-2 cells was significantly inhibited by IBE (p<0.001 at 100 µg/mL). Increased production of inflammatory mediators such as iNOS, COX-2 and TNF-α (p < 0.01 and p < 0.001 at 100 and 200 µg/ml, respectively) was attenuated by IBE concentration-dependently. IBE also scavenged DPPH radicals in a  dose-dependent manner (p < 0.05 at 10 ìg/ml and p < 0.001 at 20 - 200 µg/ml).Conclusion: These results indicate that IBE attenuated neuroinflammatory responses in LPS-activated BV-2 microglia by inhibiting excessive  production of pro-inflammatory mediators such as NO, iNOS, COX-2 and TNF-α. The anti-neuroinflammatory potential of IBE may be related to its strong antioxidant properties.Keywords: Ipomoea batatas, DPPH radicals, Anti-oxidant,  Neuroinflammation, BV-2 microglia, Nitric oxide

Mixed Covolume Methods on Rectangular Grids for Elliptic Problems

We consider a covolume method for a system of first order PDEs resulting from the mixed formulation of the variable-coefficient-matrix Poisson equation with the Neumann boundary condition. The system may be used to represent the Darcy law and the mass conservation law in anisotropic porous media flow. The velocity and pressure are approximated by the lowest order Raviart-Thomas space on rectangles. The method was introduced by Russell [Rigorous Block- centered Discretizations on Irregular Grids: Improved Simulation of Complex Reservoir Systems, Reservoir Simulation Research Corporation, Denver, CO, 1995] as a control-volume mixed method and has been extensively tested by Jones [A Mixed Finite Volume Elementary Method for Accurate Computation of Fluid Velocities in Porous Media, University of Colorado at Denver, 1995] and Cai et al. [Computational Geosciences, 1 (1997), pp. 289-345]. We reformulate it as a covolume method and prove its first order optimal rate of convergence for the approximate velocities as well as for the approximate pressures