Changes in reflex excitability following isometric contraction in humans

The dose rate at which cells are exposed to X-rays may influence the nature of induced mutations. To investigate this, the molecular spectra were determined at the HPRT gene in a hamster (V79) and a human (WI-L2-NS) cell line after the same total dose of X-rays has been administered at either a low dose rate (LDR; 3.33 mGy/min) or a high dose rate (HDR; 1.24-1.4 Gy/min) X-irradiation. Mutational spectra appeared similar, the fraction of mutants carrying deletions ranging between 59%-66% for the V79 strain and between 64%-75% for the WI-L2-NS strain, and independent of the irradiation conditions. The data indicate no effect of ongoing repair processes under LDR conditions on the kind of induced mutations in mammalian cells.