Observations on the effect of X-ray alone and in combination with ultrasound on human chromosomes

Human peripheral blood was treated with ultrasound either before or after irradiation, and chromosome aberrations in lymphocytes of peripheral blood cultures compared to those resulting from an equivalent dose of irradiation given alone. When peripheral blood is sonicated at a high intensity (3 W/cm2) for 10 min after irradiation, there is an increase in aberration frequency as compared to control samples receiving the equivalent radiation dose alone. However, should the blood be sonicated at the same frequency and for the same time period before radiation there is no significant increase in total chromosome aberrations over the irradiated controls. On the contrary a significant decreases occurs in certain classes of aberration. When sonification with a lower intensity (20 mW/cm2) was used in combination with irradiation the reverse effect was noted. Ultrasound administered for 10 min after radiation caused no significant increase in aberrations. On the contrary increasing the period of sonification to one hour resulted in a lowering of all types of aberration, significant in the case of dicentrics and total chromosome aberrations, when compared to irradiation alone. Reversing the order of treatment again resulted in the opposite effect to that achieved with comparable experiments at high intensities of sonification. Ultrasound before radiation did not produce lower breakage rates. Instead, when the period of sonification was increased to one hour, the number of aberrant cells, fragments, and total aberrations rose significantly over controls. It is suggested that sonification produces chemical changes affecting cellular repair systems, which when combined with ionising radiation, results in an increased or decreased repair effect depending on the dose, duration, and order of treatment.