Shape of dose-survival curves for mammalian cells and repair of potentially lethal damage analyzed by hypertonic treatment
During the usual procedure of testing cell survival by colony-forming ability, repair of potentially lethal damage (PLD) takes place. By incubating the cells in hypertonic suspension a certain part of this repair can be inhibited, leading to an exponential dose-survival curve as expected from the Poisson distribution of lethal events in the cells. If such a hypertonic treatment is performed after increasing intervals following irradiation with x rays, curves with increasing shoulder length are obtained. Quantitative analysis of the kinetics of this repair shows that PLD is repaired for about 1 h after irradiation by a saturated repair system which eliminates about one lesion per 15 min per cell independent of the applied absorbed dose. PLD not eliminated by this last system is repaired by an unsaturated system with a time constant of several hours. Repair of PLD after x irradiation proceeds quantitatively in this way in plateau-phase cells suspended in a conditioned medium, which seems optimal for such repair. If these cells are suspended after irradiation in normal nutrient medium a certain fraction of the PLD is transformed into irreparable damage. The final survival after repair in nutrient medium is then identical with that obtained by the usual measurement of colony-forming ability on nutrient agar. This indicates that the shoulder in dose-survival curves for plateau phase cells ispartly due to repair of PLD and partly due to manifestation of this damage during repair time.
- Research Organization:
- Gesellschaft fuer Strahlen, Frankfurt am Main, Germany
- OSTI ID:
- 6042410
- Journal Information:
- Radiat. Res.; (United States), Vol. 87:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
TUMOR CELLS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL REPAIR
COLONY FORMATION
DOSE-RESPONSE RELATIONSHIPS
HYPERTONIC SOLUTIONS
MAMMALS
RADIOSENSITIVITY
SURVIVAL CURVES
TIME DEPENDENCE
X RADIATION
ANIMAL CELLS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
DISPERSIONS
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
MIXTURES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
SOLUTIONS
VERTEBRATES
560121* - Radiation Effects on Cells- External Source- (-1987)
550603 - Medicine- External Radiation in Therapy- (1980-)