PURPOSE: In this study the kinetics of recovery following irradiation was examined in a human glioma cell line. Specific objectives were: to determine whether recovery is mono- or biexponential in nature; to determine if recovery half-times are different in exponential and plateau growth phase cells; to compare recovery half-times as a function of dose or recovery levels; and finally, to compare the kinetics of sublethal damage recovery and potentially lethal damage recovery in plateau growth phase cells. METHODS AND MATERIALS: U-87MG cells were irradiated in exponential and plateau growth phases and then subjected to incubation at 37 degrees C for various periods of time following or between doses prior to assaying for survival. Survival recovery curves were fit to a sum of exponential terms. RESULTS: Potentially lethal damage recovery was monoexponential in both exponential and plateau growth phase cells and occurred at the same rate when isorecovery values were compared. Recovery half-times increased in an exponential manner within the observed dose range. Recovery between doses of radiation (sublethal damage recovery) proceeded at a slower rate than recovery following a single dose of radiation (potentially lethal damage recovery). CONCLUSIONS: This study suggests that potentially lethal damage recovery is a saturated process and that the recovery half-time may increase in a linear-quadratic exponential function of dose similar to the absolute recovery level. In addition, if iso-recovery levels are compared, the recovery half-time is similar in rapidly and slowly proliferating cell populations.
PURPOSE: In this study the kinetics of recovery following irradiation was examined in a humanglioma cell line. Specific objectives were: to determine whether recovery is mono- or biexponential in nature; to determine if recovery half-times are different in exponential and plateau growth phase cells; to compare recovery half-times as a function of dose or recovery levels; and finally, to compare the kinetics of sublethal damage recovery and potentially lethal damage recovery in plateau growth phase cells. METHODS AND MATERIALS: U-87MG cells were irradiated in exponential and plateau growth phases and then subjected to incubation at 37 degrees C for various periods of time following or between doses prior to assaying for survival. Survival recovery curves were fit to a sum of exponential terms. RESULTS: Potentially lethal damage recovery was monoexponential in both exponential and plateau growth phase cells and occurred at the same rate when isorecovery values were compared. Recovery half-times increased in an exponential manner within the observed dose range. Recovery between doses of radiation (sublethal damage recovery) proceeded at a slower rate than recovery following a single dose of radiation (potentially lethal damage recovery). CONCLUSIONS: This study suggests that potentially lethal damage recovery is a saturated process and that the recovery half-time may increase in a linear-quadratic exponential function of dose similar to the absolute recovery level. In addition, if iso-recovery levels are compared, the recovery half-time is similar in rapidly and slowly proliferating cell populations.
Authors: Caroline Steenken; Jens Fleckenstein; Stefan Kegel; Lennart Jahnke; Anna Simeonova; Linda Hartmann; Jens Kübler; Marlon R Veldwijk; Frederik Wenz; Carsten Herskind; Frank Anton Giordano Journal: Strahlenther Onkol Date: 2015-03-13 Impact factor: 3.621