![Sample our Medicine, Dentistry, Nursing & Allied Health journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5944/TOC-Subject-Sample-2021-Medicine-Dentistry-Nursing-Allied-Health.jpg"})
Abstract
Purpose: The purpose of the paper was to investigate the protective effect of some scavengers of OH radicals (hydroxyl radicals) on the radiation sensitivity of bacteria (in some cases also yeast) under normoxic (in air) or hypoxic (suboxic) conditions and to compare the obtained results with those published earlier for the yeast, all in a wide interval of irradiation conditions. Another aim was to investigate a possible impact of the reaction order of the reaction between the scavengers and the OH radicals on the protection of the cells.
Materials and Methods: In order to study the protective effect of OH scavengers we used various concentrations of methanol and potassium formate (in some cases also ethanol) in isotonic salt solutions. These solutions containing living bacteria (Escherichia coli) or yeast (Saccharomyces cerevisiae) were irradiated with 60Co radiation using various doses and dose rates. Irradiation was performed in air, in some cases under the hypoxic conditions. The number of surviving cells was determined prior to and after irradiation in suspension with and without scavengers. The surviving fractions after irradiation with and without scavenger were evaluated.
Results: The surviving fraction of bacterial cells increases linearly with increasing concentration of both scavengers. The fraction of surviving cells does not increase with increasing concentration of the scavengers under suboxic conditions. The protective effect Ϭ increases linearly with increasing scavenging efficiency and this dependence is much sharper under normoxic conditions than under suboxic ones. The specific protection k is much higher for the methanol than for the potassium formate.
Conclusions: The basic characteristics of the impact of scavengers of OH radicals on radiation sensitivity of both bacteria and yeast are the same in a wide interval of doses and dose rates. The specific protection effect is much higher under the normoxic conditions. This protective effect is inversely proportional to the rate constant of the reaction between the scavenger and the OH radicals. It seems to be obvious that the presence of oxygen during irradiation is a necessary condition for the protective action of the scavengers which may be partially controlled by some transport processes and may be connected with the radiation sensitivity of the cells. On the other hand, the change of the reaction order of the reaction of the scavenger with the OH radicals has turned out to be unimportant.
Acknowledgements
The authors thank to prof. K. Demnerova from ICT Prague for providing of the bacteria and yeast strain.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
Notes on contributors
Viliam Múčka
Viliam Múčka, head of the radiation chemistry group, is a professor at Czech Technical University in Prague. His research has been focused on radiation chemistry. In this field, he has been studying the effects of various chemical species on radiation sensitivity of cells.
Jaroslav Červenák
Jaroslav Červenák obtained his master degree at Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering. His PhD study has been focused on the interactions of ionizing radiation with matter.
Dan Reimitz
Dan Reimitz obtained his master degree at CTU in Prague, Faculty of Nuclear Sciences and Physical Engineering. His research focused on the study of radiation protectors and cis- platinum as a radio- sensitizer.
Václav Čuba
Václav Čuba is a vice-dean at Czech Technical University in Prague, Faculty of nuclear Sciences and Physical Engineering. His research has been focused on radiation chemistry, photochemistry and nanotechnologies.
Pavel Bláha
Pavel Bláha is finishing his PhD study at the Czech Technical University in Prague. After receiving his master's degree in the nuclear chemistry in biology and medicine at the CTU in Prague, he studies the effects of different types of ionizing radiation on the induction of mutations in mammalian cells.
Barbora Neužilová
Barbora Neužilová is a PhD student at the Czech Technical University in Prague. After receiving a diploma degree in nuclear chemistry in biology and medicine at the CTU in Prague, she studies the modification of radiation sensitivity of cells by chemical agents.