Hyperthermic effects on DNA repair mechanisms.

Studies have been carried out using neutral and alkaline sucrose density gradients to investigate the effect of 41 degree-43 degree C on the ability of Chinese hamster ovary cells to repair single (SSB) and double stranded DNA breaks (DSB) caused by exposure to ionizing radiation. The authors found that when hyperthermia exists prior to irradiation significant inhibition occurs. The data support the conclusion that unrepaired DNA damage may be lethal to the cell. Though no increase in radiation-induced DSB frequency was observed subsequent to hyperthermia, a 10-20% increase in SSB frequency was observed.