title: Simple radiosensitizing of hypoxic tumor tissues by N2O/Br(-) mixture.
abstract: The radiosensitization model of hypoxic tumor tissues based on the N2O/Br(-) mixture is described. The well-documented radiolysis of water in the presence of N2O and Br(-) ions at a low concentration supports this model. An aqueous solution saturated with N2O gas during the radiolysis generates OH radicals in a large extent. In N2O/Br- media at pH<9, Br2 is formed. Br2 hydrolyzes in an aqueous solution to form a very reactive hypobromous (HOBr) acid. Such process is described by the following chemical reaction: H2O + Br(-) + N2O + ionizing radiation (IR) --> HOBr + OH(-). In vivo formed HOBr as a long-lived product with a high biological activity induces the hypoxic tumor cell damage via many unique mechanisms. A local application or inhalation of an N2O-O2 mixture before or during the radiotherapy to enhance the saturation of tissues with N2O is a key prerequisite. Since the extracellular concentration of Br(-) ions is very low (0.02-0.05 mM), an oral or local application of NaBr should be used to shift the extracellular concentration of Br(-) ions to the mM region.
authors: Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská Dolina, SK-842 15 Bratislava, Slovakia; Department of Magnetometry, Institute of Measurement Science, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia. Electronic address: billik@fns.uniba.sk.
authors: P
authors: P
authors: Billik
mesh_terms: D001966:Bromine / Q000008:administration & dosage*; D015687:Cell Hypoxia; D006801:Humans; D009369:Neoplasms / Q000473:pathology*; D009609:Nitrous Oxide / Q000008:administration & dosage*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*
chemical_list: D011838:Radiation-Sensitizing Agents; D009609:Nitrous Oxide; D001966:Bromine