Repair of neoplastic transformation damage following protracted exposures to /sup 60/Co. gamma. -rays

Technical Report · Sat Jan 01 04:00:00 EST 1983

DOI:https://doi.org/10.2172/5598193· OSTI ID:5598193

Han, A; Hill, C K; Elkind, M M

The incidences of neoplastic transformation induced by /sup 60/Co ..gamma..-rays in exponentially growing mouse embryo 10T1/2 cells were measured following acute and protracted exposures. Delivery of /sup 60/Co ..gamma..-rays at a low dose rate (0.1, 0.5, 2.5 rad/min) compared with a high dose rate (100 rad/min) results in appreciable, dose rate dependent reductions in cell killing and, independent of the effect on cell survival, reduces significantly the incidence of neoplastic transformation. Exposure of exponentially growing 10T1/2 cells to a dose of ..gamma..-rays in five equal daily fractions also significantly reduces transformation frequency, compared with delivery in a single dose, throughout the dose range examined (25 to 300 rads). The initial parts of the induction curves are fitted quite well by a linear dose dependence. The slopes of the regression lines for multifractionation delivery or irradiation at 0.1 rad/min, are one-third and one-half, respectively, of those for single exposures at a high dose rate. Increasing the interfraction interval up to 48 hours, or reduction of the dose per fraction further reduce incidence of neoplastic transformation. We conclude that protracted exposures of low LET radiation result in a net error-free repair of subtransformation damage.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5598193
• Report Number(s): CONF-830782-1; ON: DE83015684
• Country of Publication: United States
• Language: English

Related Subjects

560121* -- Radiation Effects on Cells-- External Source-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL CULTURES
COBALT 60
COBALT ISOTOPES
DATA
DOSE RATES
DOSE-RESPONSE RELATIONSHIPS
ELECTROMAGNETIC RADIATION
EMBRYOS
EXPERIMENTAL DATA
FRACTIONATED IRRADIATION
GAMMA RADIATION
INFORMATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
IRRADIATION
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAMMALS
MICE
MINUTES LIVING RADIOISOTOPES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ONCOGENIC TRANSFORMATIONS
RADIATIONS
RADIOINDUCTION
RADIOISOTOPES
RECOVERY
REPAIR
RODENTS
VERTEBRATES
YEARS LIVING RADIOISOTOPES