Involvement of nitric oxide/reactive oxygen species signaling via 8-nitro-cGMP formation in 1-methyl-4-phenylpyridinium ion-induced neurotoxicity in PC12 cells and rat cerebellar granule neurons.

To investigate the role of nitric oxide (NO)/reactive oxygen species (ROS) redox signaling in Parkinson's disease-like neurotoxicity, we used 1-methyl-4-phenylpyridinium (MPP) treatment (a model of Parkinson's disease). We show that MPP-induced neurotoxicity was dependent on ROS from neuronal NO synthase (nNOS) in nNOS-expressing PC12 cells (NPC12 cells) and rat cerebellar granule neurons (CGNs). Following MPP treatment, we found production of 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), a second messenger in the NO/ROS redox signaling pathway, in NPC12 cells and rat CGNs, that subsequently induced S-guanylation and activation of H-Ras.

Enhancement of Structural fluctuation in the region connecting two kinds of critical points in temperature-pressure-composition three-dimensional phase diagram: Raman studies of benzene/CO2 binary systems up to supercritical region.

Pressure dependence of Raman spectra of benzene/CO2 two-component systems was systematically studied at different temperatures and compositions. We estimated the magnitude of inhomogeneous component in Raman bandwidth to get information on the structural fluctuation in the system. It was found that the inhomogeneous bandwidth attains a maximum on an isothermal plane in the temperature-pressure-composition three-dimensional phase diagram when the state point crosses the line connecting the region where the density fluctuation is large (the vicinity of the critical point of neat CO2) and the region where the concentration fluctuation in a binary system is enhanced (the vicinity of the critical solution point).