Factors influencing the repair of potentially lethal radiation damage in growth-inhibited human cells
The cells in growth-inhibited (stationary phase) cultures of Chang human liver cells (LICH) will repair potentially lethal radiation damage (PLD repair) if allowed to remain in the stationary phase of growth for several hours after irradiation. The half-time for PLD repair was 1 to 2 hr, and it was associated with a change in the slope of the survival curve. Repair was independent of whether the cells reached stationary growth by density-inhibition or medium exhaustion. It depended on both cell to cell contact and some factor that developed in the medium of stationary phase cultures. PLD repair was greatly reduced by incubating stationary cultures in fresh medium during the repair interval, whereas a small amount of repair with similar kinetics could be induced in exponentially growing cells by postirradiation incubation with conditioned medium from densityinhibited cultures. Incubation of stationary or exponentially growing cells with conditioned medium impeded the progression of G/sub 1/ cells into S. The repair process occurs primarily in cells in the Gi phase of the life cycle. On the basis of these results, it is hypothesized that cells in stationary phase cultures are held up in a particular metabolic state in G/sub 1/ , which favors the efficient repair of potentially lethal lesions. Conditions that allow the cells to leave this state and progress into S favor fixation of damage and reduced survival. (auth)
- Research Organization:
- Harvard Univ., Boston
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-005283
- OSTI ID:
- 4404778
- Journal Information:
- Radiat. Res., v. 56, no. 2, pp. 320-333, Journal Name: Radiat. Res., v. 56, no. 2, pp. 320-333; ISSN RAREA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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