title: Effects of gamma radiation and hyperthermia on DNA repair synthesis and the level of NAD+ in cultured human mononuclear leukocytes.
abstract: DNA repair has been investigated, estimated by unscheduled DNA synthesis (UDS) and the cellular NAD+ pool, after exposing human mononuclear leukocytes to hyperthermia and gamma radiation separately and in combination. It was found that gamma radiation induced a decline in UDS with increasing temperature through the temperature region studied (37-45 degrees C). At 42.5 degrees C the gamma-ray-induced UDS was reduced to about 70% of that at 37 degrees C. Following gamma-ray damage the NAD+ pool dropped to about 20% of control values. Without hyperthermic treatment the cells completely recovered to the original level within 5 hr. Moderate hyperthermia (42.5 degrees C for 45 min) followed by gamma-ray damage altered the kinetics so that even after 8 hr the NAD+ pool had recovered to only 70% of the original level. After heat treatment at 44 degrees C for 45 min prior to gamma radiation the cells did not recover at all, presumably because of the cytotoxic effects from the combined treatment.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism / Q000528:radiation effects; D000249:Adenosine Monophosphate / Q000378:metabolism / Q000528:radiation effects; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D005720:Gamma Rays; D006801:Humans; D006979:Hyperthermia, Induced; D009000:Monocytes / Q000378:metabolism / Q000528:radiation effects*; D009243:NAD / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors
chemical_list: D009243:NAD; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D004247:DNA