Increased Nitric Oxide Production and GFAP Expression in the Brains of Influenza A/NWS Virus Infected Mice

The cause of influenza to the brain was investigated using the A/NWS/33 influenza virus infected BALB/c mouse model. NOS-2 mRNA levels in the infected mouse brain was greater than in control mice in all brain regions examined, particularly in the olfactory bulb and hippocampus by 1 day p.i. On the contrary, no differences in NOS-1 or NOS-3 mRNA levels were found between infected and control mice. There was also a marked increase in the levels of metabolites of nitric oxide in the olfactory bulb and hippocampus. Immunohistochemistry showed positive staining for anti-NOS-2 primarily in the hippocampus of infected mice. Further, anti-NOS-2 and GFAP staining was mostly found around capillary blood vessels of the hippocampus starting early in the course of the disease. These results indicate that the NWS enhances the activation of astrocytes and NOS-2 expression which in turn enhances NO production and the expansion of capillary blood vessels

New Insights in the Contribution of Voltage-Gated Nav Channels to Rat Aorta Contraction

BACKGROUND: Despite increasing evidence for the presence of voltage-gated Na(+) channels (Na(v)) isoforms and measurements of Na(v) channel currents with the patch-clamp technique in arterial myocytes, no information is available to date as to whether or not Na(v) channels play a functional role in arteries. The aim of the present work was to look for a physiological role of Na(v) channels in the control of rat aortic contraction. METHODOLOGY/PRINCIPAL FINDINGS: Na(v) channels were detected in the aortic media by Western blot analysis and double immunofluorescence labeling for Na(v) channels and smooth muscle alpha-actin using specific antibodies. In parallel, using real time RT-PCR, we identified three Na(v) transcripts: Na(v)1.2, Na(v)1.3, and Na(v)1.5. Only the Na(v)1.2 isoform was found in the intact media and in freshly isolated myocytes excluding contamination by other cell types. Using the specific Na(v) channel agonist veratridine and antagonist tetrodotoxin (TTX), we unmasked a contribution of these channels in the response to the depolarizing agent KCl on rat aortic isometric tension recorded from endothelium-denuded aortic rings. Experimental conditions excluded a contribution of Na(v) channels from the perivascular sympathetic nerve terminals. Addition of low concentrations of KCl (2-10 mM), which induced moderate membrane depolarization (e.g., from -55.9+/-1.4 mV to -45.9+/-1.2 mV at 10 mmol/L as measured with microelectrodes), triggered a contraction potentiated by veratridine (100 microM) and blocked by TTX (1 microM). KB-R7943, an inhibitor of the reverse mode of the Na(+)/Ca(2+) exchanger, mimicked the effect of TTX and had no additive effect in presence of TTX. CONCLUSIONS/SIGNIFICANCE: These results define a new role for Na(v) channels in arterial physiology, and suggest that the TTX-sensitive Na(v)1.2 isoform, together with the Na(+)/Ca(2+) exchanger, contributes to the contractile response of aortic myocytes at physiological range of membrane depolarization

Study of the oxygen diffusion on three-way catalysts: a kinetic model

SSCI-VIDE+CARE+CDSInternational audienceNon

Study of the oxygen diffusion on three-way catalysts: a kinetic model

SSCI-VIDE+CARE+CDSInternational audienceA computer model was developed to take into account all the phenomena that can occur in O-18/O-16 isotopic exchange over Pt/ CeZrOx materials: adsorption/desorption on the metal, surface and bulk O diffusion. Discriminating each step of the exchange process is no longer necessary: kinetic parameters and O diffusivity can be calculated in a single experiment

Surface mobility and redox properties : study of Pt/CeO2-ZrO2 catalysts

SSCI-VIDE+CARE+CDSInternational audienceNon

Characterization of the dynamic oxygen migration over Pt/CeO2-ZrO2 catalysts by 18O/16O isotopic exchange reaction

SSCI-VIDE+CARE+CDSInternational audienceNon

Characterization of the dynamic oxygen migration over Pt/CeO2-ZrO2 catalysts by O-18/O-16 isotopic exchange reaction

SSCI-VIDE+CARE+CDSInternational audienceTo characterize the oxygen mobility over metal supported catalysts on a dynamic and in situ base, O-18/O-16 isotopic exchange reaction combined with CO oxidation was designed and exemplified on three kinds of three way catalysts of Pt/CeO2-ZrO2 (CZ-O, CZ-D and CZ-R). The obtained oxygen diffusion coefficients, oxygen release rate, and oxygen storage capacity were discussed and correlated with XRD spectra and other physical parameters. It was found that the oxygen mobility and oxygen storage capacity were parallel to the structural homogeneity of Zr introduction into the CeO2 frame work, and decreased as: CZ-R > CZ-D > CZ-O. These results indicated that this combined isotopic exchange technique could be used to quantify the surface and bulk oxygen mobility, the oxygen storage capacity and oxygen release rate over the metal supported catalysts, and could be employed as a meaningful probe into the nature of CeO2-ZrO2 oxygen storage material. The oxygen mobility is also another important indicator for the development of oxygen storage materials. (C) 2004 Elsevier B.V. All rights reserved

Oxygen mobility and dynamic performance over model three-way Pt/CeO2-ZrO2 catalysts

SSCI-VIDE+CARE+CDSInternational audienceNon