245 Apoptosis induced by low intensity ultrasound： a search for an optimal condition

Apoptosis is a gauge for radiation and hyperthermia therapy. Ultrasound (US) has been used in cancer therapy as a heating device; while recent study showed that nonthermal US is also capable of inducing apoptosis. However, yield is low and cell lysis is predominant. To search for an optimal apoptosi...

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Published in:JOURNAL OF RADIATION RESEARCH 2003, Vol.44 (4), p.447-447
Main Authors: Loreto FERIL, Takashi KONDO, Zheng Guo CUI, Qing-Li ZHAO, Ryohei OGAWA, Hidemi HONDA
Format: Article
Language:Japanese
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Summary:Apoptosis is a gauge for radiation and hyperthermia therapy. Ultrasound (US) has been used in cancer therapy as a heating device; while recent study showed that nonthermal US is also capable of inducing apoptosis. However, yield is low and cell lysis is predominant. To search for an optimal apoptosis (highest apoptosis/lysis ratio), we applied different US conditions by varying the intensity, duty factor (DF), pulse repetition frequency (PRF) and duration of exposure. Sonicated U937 cells were incubated at different time intervals before measuring the apoptosis and its signal transduction. Apoptosis was assessed by morphological changes, DNA fragmentation and phosphatidylserine externalization. Decrease in MMP was also determined. Optimal apoptosis (70.0+13.8%) was attained at 1 MHz, 0.3 W/cm2, 10% DF of 100 Hz PRF for 1 min. Apoptosis peaked at 12 hr after irradiation. This level of apoptosis is comparable to apoptosis induced by X-irradiation above 20 Gy, suggesting that US is competitive in terms of apoptosis induction.
ISSN:0449-3060