Failure to confirm increase in unscheduled DNA synthesis in sonicated mammalian cells in vitro

Two in vitro mammalian cell lines (HeLa, mouse L5178Y) were exposed/sham exposed to ultrasound (2.3 or 2.6 MHz, I-SPTA 35 W cm-2, 10 microseconds burst duration, 200 Hz pulse repetition frequency) for 20 min and subsequently autoradiographically scored for unscheduled DNA synthesis (UDS). A positive control (20 and 40 J m-2 germicidal ultraviolet at a flux density of 1 J m-2 s-1) yielded statistically significant increases in UDS; no such increase was observed for the ultrasound regimens. The results fail to confirm an earlier report by Liebeskind et al. of ultrasound-induced increases in UDS.