Analyzing the role of biochemical processes in determining response to ionizing radiations

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Health Physics; (USA)

DOI:https://doi.org/10.1097/00004032-198907001-00052· OSTI ID:7167634

Nelson, J M; Braby, L A; Metting, N F; Roesch, W C ^[1]

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1. Pacific Northwest Laboratory, Richland, WA (USA)

The interaction of biochemical processes and radiation damage appears to play a major role in determining long-term biological effects. It is responsible for both the removal of radiation-induced alterations in macromolecules and for the time-dependent changes in survival of irradiated cells. Restoration of macromolecules by such means as the rejoining of strand breaks in DNA suggests a variety of possible mechanisms which could lead to the observed enhancement of cell survival. However, even though a number of molecular repair mechanisms have been identified, specific links between any such mechanisms and a subsequent modification of cell survival have proved difficult, if not impossible, to demonstrate. Models of cellular response provide a means of attempting to establish this connection. Although details of radiation chemistry, chromatin structure, enzymatic repair, molecular genetics, and cell cycle kinetics are generally simplified, each individual model incorporates features based on a set of assumed mechanisms. For example, one group of models assumes that all damage is potentially lethal, while another assumes that part of the damage is sublethal. Using split-dose, dose-rate, and delayed-plating techniques, we have demonstrated two distinct components of repair in plateau-phase Chinese hamster ovary cells. One process has a characteristic time of about 1 h; the other, about 18 h. In both cases, the reaction rates and the fractions of damage repaired appear to be independent of the initial amounts of damage produced. These observations suggest that none of the simpler models adequately describes cell inactivation; i.e., reproductive death is inconsistent with all assumptions regarding any of them. Consequently, more-complex models involving combinations of sublethal and potentially lethal damage or multiple-step damage processes may be required.

• OSTI ID: 7167634
• Journal Information: Health Physics; (USA), Journal Name: Health Physics; (USA); ISSN 0017-9078
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CHO CELLS
DNA REPAIR
DNA
DOSE-RESPONSE RELATIONSHIPS
GENETIC RADIATION EFFECTS
HAMSTERS
IN VITRO
STRAND BREAKS
SURVIVAL TIME
TIME DEPENDENCE
ANIMAL CELLS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
GENETIC EFFECTS
MAMMALS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
RADIATION EFFECTS
RECOVERY
REPAIR
RODENTS
VERTEBRATES
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture