Abstract : The objective of this study was to determine the kinetics of nuclear factor-kappa B (NF-kappaB) act
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Abstract : The objective of this study was to determine the kinetics of nuclear factor-kappa B (NF-kappaB) activation and cytokine expression in bone marrow (BM) cells of exposed mice as a function of the dose rate of protons. The cytokines included in this study are pro-inflammatory i.e. tumor necrosis factor-alpha (TNF-alpha) interleukin-1beta (IL-1beta) and IL-6 and anti-inflammatory cytokines (i.e. IL-4 and IL-10). We gave male BALB/cJ mice a whole-body exposure to 0 (sham-controls) or 1.0 Gy of 100 MeV protons delivered at 5 or 10 mGy min(-1) the dose and dose rates found during solar particle events in space. As a reference radiation groups of mice were exposed to 0 (sham-controls) or 1 Gy of (137)Cs gamma rays (10 mGy min(-1)). After irradiation BM cells were collected at 1.5 3 24 h and 1 month for analyses (five mice per treatment group per harvest time). The results indicated that the in vivo time course of effects induced by a single dose of 1 Gy of 100 MeV protons or (137)Cs gamma rays delivered at 10 mGy min(-1) was similar. Although statistically significant levels of NF-kappaB activation and pro-inflammatory cytokines in BM cells of exposed mice when compared to those in the corresponding sham controls (Students t-test p lt 0.05 or lt0.01) were induced by either dose rate these levels varied over time for each protein. Further only a dose rate of 5 mGy min(-1) induced significant levels of anti-inflammatory cytokines. The results indicate dose-rate effects of protons.
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