P07 MHz超音波により誘導されるU937細胞のシグナルトランスダクション

抄録

Megahertz ultrasound use harmless technique for diagnosis and therapeutic technique. However, megahertz ultrasound technique induces irreparable damage to body tissue. In our studies, we aimed to assess safety of megahertz ultrasound and further investigate the mechanism of megahertz ultrasound induced gene expression. Continuous-wave ultrasound in the range of frequency of 1.0 MHz to 5.7 MHz was delivered to human myeloid leukemia U937 cells. Ultrasound exposure was delivered with 10-seconds and a various intensity level, which was determined by calorimetry and verified with ultrasonic hydrophone. As a result, induced gene expression was different by ultrasound irradiance condition. The effect of ultrasound on the rate of cell proliferation was evaluated using a particle counter in all frequencies after irradiation 72 h. The effect of ultrasound cell membrane damage was observed in the frequency range from 1.0 MHz to 3.4 MHz. Cell membrane damage was tested using a flow cytometer. We also observed apoptotic cells at 5.7 MHz using a flow cytometer. These results were caused presumably with generation of free radical by ultrasound cavitation. We determined quantity of free radical by ultrasound exposure using an electron spin resonance in order to confirm relevance gene expression and free radical. We intend to report various biological effect of megahertz ultrasound on human myeloid leukemia U937 cells.