International equatorial electrojet year : the African sector

International audienceThis paper presents the IEEY project in the African sector. The amount of our interpreted data is presently too short to allow proper scientific conclusions. Nevertheless, fist typical results illustrate our network possibilities. Some preliminary observations are briefly pre- , sented for their interest towards immediate research goals

IFN-γ signaling, with the synergistic contribution of TNF-α, mediates cell specific microglial and astroglial activation in experimental models of Parkinson's disease

To through light on the mechanisms underlying the stimulation and persistence of glial cell activation in Parkinsonism, we investigate the function of IFN-γ and TNF-α in experimental models of Parkinson's disease and analyze their relation with local glial cell activation. It was found that IFN-γ and TNF-α remained higher over the years in the serum and CNS of chronic Parkinsonian macaques than in untreated animals, accompanied by sustained glial activation (microglia and astroglia) in the substantia nigra pars compacta. Importantly, Parkinsonian monkeys showed persistent and increasing levels of IFN-γR signaling in both microglial and astroglial cells. In addition, experiments performed in IFN-γ and TNF-α KO mice treated with MPTP revealed that, even before dopaminergic cell death can be observed, the presence of IFN-γ and TNF-α is crucial for microglial and astroglial activation, and, together, they have an important synergistic role. Both cytokines were necessary for the full level of activation to be attained in both microglial and astroglial cells. These results demonstrate that IFN-γ signaling, together with the contribution of TNF-α, have a critical and cell-specific role in stimulating and maintaining glial cell activation in Parkinsonism

Study of the equatorial electrojet starting from the electrodynamics parameters of the equatorial ionosphere

Abstract The determination of the physical parameters of the equatorial electrojet (EEJ) from Korhogo (Latitude +9.3; Longitude -5.4; Dip -0.67) during the period of 1993 to 1994 was carried out by data of ionosonde IPS-42. The results made it possible to show that for a low average value of electron drift vertical approximately 5 m/s to the solstices and 6 m/s with the equinoxes in the morning, we obtained around midday a strong density of current of the EEJ (3.30A/km 2 in 1993 and 2.6A/km 2 in 1994). We determined during this study the values of the various electric fields intervening in the mechanism of formation of the EEJ. We showed the strong contribution of the polarization electric field in this phenomenon. The results gave the values of the zonal and polarization electric fields respectively 0.19mV/m and 3.5mV/m. The data of ionosonde IPS-42 made it possible to determine the density and intensity of current center of the EEJ (I 0 =231.11±53.7 A/km). We compared the intensity of the current in the center obtained with the ionosonde with that of the data on the ground. We obtained appreciably similar results

Ultrastructural Effects of Postharvest Treatments on the Vacuolar Inclusions in Pear (Pyrus Communis L. CV. Hardenpoint) Peel

In the course of our investigations on the ultrastructural effects of postharvest treatments applied for shelf life extension of hardenpont pear, we have observed specific changes in the vocuolar content of peel. In the hypodermal cells of the untreated control compact dense vacuolar inclusions developed during storage for two months. CaCl2 solution applied after picking changed the structure of the inclusions by the end of storage, while gamma-irradiation (1 kGy) possible ultrastructural markers of the treatments. We have not found evidence by X-ray micro-analysis for the accumulation of Ca in the inclusions after CaCl2 treatment, while Ca accumulated in the vacuolar granules of the fruit flesh