Induction of sister-chromatid exchanges in human lymphocytes exposed in vitro and in vivo to therapeutic ultrasound

Abstract

The induction of sister-chromatid exchanges (SCEs), chromosomal aberrations and cell-cycle delay was determined in human lymphocytes after treatment in vitro and in vivo with therapeutic ultrasound (u.s.). In vitro treatments (1 W/cm 2; 0.860 MHz; for 40–160 sec) were performed on unstimulated lymphocytes from 9 donors: a statistically significant, dose-dependent increase in SCE frequency was produced, whereas no induction of chromosomal aberrations nor alteration of the distribution of 1st, 2nd and 3rd division metaphases were observed. The same increase in the frequency of SCEs was detected by treating in vitro stimulated lymphocytes with u.s. The effects of in vivo exposure to u.s. were detected on lymphocytes from 10 patients before, during and after u.s. therapy (0.6–1.0 W/cm 2; 0.860 MHz; from 8 to 20 applications lasting 5–6 min each). SCE frequency was statistically significantly increased in all patients at mid-therapy, without a further increase during the second half of therapeutic cycle, and was restored to pretreatment level 3 months after the end of u.s. therapy. No increase in chromosomal aberrations was noticed during and after u.s. therapy, whereas erratic delays of the cell cycle were observed, not clearly related to u.s. application or SCE levels. A linear relationship was found between SCE frequency and age in 21 healthy donors.