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  • Author: P. V. Ramachandran x
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Abstract

Complete and incomplete fusion cross-sections for the 9Be+124Sn system have been measured around the Coulomb barrier energies (E lab C.B=28 MeV) using the on-line gamma ray detection technique. The complete fusion cross-sections of this system have been compared with the two stable projectiles on the same 124Sn target to provide information on the projectile dependence. The brief comparison of the present 9Be+124Sn data with a comprehensive and recent study of the neighbouring system 9Be+144Sm is also given.

Abstract

Reactive oxygen species have been implicated in the activation of signal transduction pathways. However, extracellular addition of oxidants such as hydrogen peroxide (H2O2) often requires concentrations that cannot be readily achieved under physiological conditions to activate biological responses such as apoptosis. Explanations for this discrepancy have included increased metabolism of H2O2 in the extracellular environment and compartmentalization within the cell. We have addressed this issue experimentally by examining the induction of apoptosis of endothelial cells induced by exogenous addition of H2O2 and by a redox cycling agent, 2,3-dimethoxy 1,4-naphthoquinone, that generates H2O2 in cells. Here we show that low nanomolar steadystate concentrations (0.1 0.5 nmolmin 1106 cells) of H2O2 generated intracellularly activate cJun N terminal kinase and initiate apoptosis in endothelial cells. A comparison with bolus hydrogen peroxide suggests that the low rate of intracellular formation of this reactive oxygen species results in a similar profile of activation for both cJun N terminal kinase and the initiation of apoptosis. However, a detailed analysis reveals important differences in both the duration and profile for activation of these signaling pathways.