[Markers of the metabolic changes arising as a result of ionizing radiation exposure]

Time-related changes have been studied in the content of extracellular DNA, Fe(3+)-transferrin (TF), and Cu(2+)-ceruloplasmin (CP) in the blood plasma and the activity of ribonucleotide reductase (RR) in the tumor cells and spleen of mice during the development of acute lympholeukosis P-388 and after ionizing irradiation. At the initial stages of leucosis P-388, the content of extracellular DNA increases, the TF and CP pools in the blood plasma enlarge, and the RR activity in the tumor cells and spleen of tumoral mice markedly increases. A dose-dependent increase in RR activity was also recorded in the spleen of 5-day-old rats within 15-30 min after irradiation. The causes of these changes and the possibility for these indices to be used in estimating leucosis risk are discussed. Radiation-induced increases in RR activity are discussed in relation to the SOS-response to DNA damage; an increased pool of deoxyribonucleotides is necessary for repair of DNA. The mean contents of extracellular DNA, TF and CP in the blood plasma were obtained from children of different ages degrees of radioactive contamination suffering the consequences of the accident at the Chernobyl' Nuclear Power Station (n = 155). Groups of children have been isolated with increased, sharply decreased, and close to normal levels of extracellular DNA, TF, and CP. The lowered TF pool was observed in children with thyroid glands damaged by incorporated radioactive iodine with the degree of suppression determined by the dose. For most children subject to general irradiation, the TF and CP pools in the blood were higher than in the control, suggesting an adaptive response to irradiation.