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Brenn E.,Section of Radiation Biology | Mitulovic G.,Medical University of Vienna | Quint R.-M.,Section of Radiation Biology | Getoff N.,Section of Radiation Biology
In Vivo

Corticosterone in water-ethanol solution can eject "solvated electrons" (eaq-) when excited into the singlet state by monochromatic UV-light (λ=254 nm). As a consequence of this process free radicals and H+ ions were also generated. Hence, the objectives of this study were to determine the quantum yield, Q, at different corticosterone concentrations, and elucidate the fate of the generated free radicals and the involved reaction mechanisms. Because of the formation of associates, which consume a part of the emitted eaq-, the Q decrease with increase of cortisone concentration. Additionally the H+ ions scavenge and convert a part of the ejected eaq- into H-Atoms. In comparsion with progesterone, the Q of corticosterone is much higher. Evidently, this effect is due to the two OH groups of corticosterone, which act as intense emission centres for eaq-. Thereby, the generated free radicals from corticosterone lead to formation of metabolites, which were analyzed by combination of liquid-chromatography with mass spectrometry (LC/MS) method. Two of them were identified: 5α-pregnan-3α, 21-diol-11, 20-dione and 20β- dihydroxycortisone. Both have the same mass number of 348.230. To explain the involved, rather complicated processes, a probable reaction mechanism is suggested. Source

Walder G.,Section of Radiation Biology | Getoff N.,Section of Radiation Biology
Anticancer Research

In the present study, the radiation-induced effect of cytochrome c (CytC) and vitamin C (VitC) is studied with respect to survival of MCF-7 cancer cells grown in aerated media. Both, CytC and VitC, were incubated with MCF-7 cancer cells under various concentrations individually, as well as in mixture and cells were subsequently treated with γ-ray in a dose range of 0 to 30 Gy. Generally, an increase of cell survival was observed under substance treatment up to a radiation dose of 5 Gy compared to the control group. Based on the obtained results it is believed that cell survival depends strongly on the action of free radicals produced at the given concentration of the incubated CytC and VitC as well as on the specific reaction rate constants (k: l mol-1 s-1) of the involved processes. Source

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