Dose-activity relation, transition

An Arrhenius-type plot of the probability constant p (= 0.693/tl/2) shows a break between —65 and —40°C. The activation energies of the a, 0 and y peaks are identical at temperatures below the structural transition of polyethylene. These activation energies and the related pre-exponential factors agree closely with those for molecular motion in polyethylene (Table 10). If oxygen is present during irradiation, the 3 and y glow peaks are completely removed at low doses and replaced by a new peak, e, at lower temperature. The thermoluminescence emission spectra of the a, y, e and probably the j3, glow peaks are identical and correspond to the emission of aliphatic aldehydes. 

Apoptosis can be triggered by mitochondrial damage, which is followed by the release of cytochrome c and the caspase cascade [167], The BAX protein activates mitochondrial release of cytochrome c [168], while Bcl-2 is a mitochondrial protein inhibits the apoptotic process and promotes cell survival [169]. Ji et al. [163] research showed that occur a decrease in mitochondrial Bcl-2 and a markedly increase in mitochondrial level of Bax in the HepG2 cells treated with PA from 200 to 400 mM concentrations. The authors suggest that this mechanism can contribute to NASH and NAFLD installation, and especially may play an important role in the transition from steatosis to steatohepatitis in human. Other studies [170] on the effect of FAs-induced steatosis on cellular apoptosis have demonstrated that palmitic and oleic FA mixtures-induced steatosis is associated with apoptosis in hepatocyte cell cultures. Joshi-Barve s et al. [171] studies also showed that exposure to excess palmitic acid induces apoptosis and lL-8 production in hepatocytes in a relation of dose-dependent and time dependent manner, via activation of c-Jun amino terminal kinase (JNK/AP-1), and nuclear factor kappa B (NF-B) transcription factors for IL-8 expression. 

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