TY - JOUR
T1 - Optimization of enhancement of therapeutic efficacy of ultrasound
T2 - Frequency-dependent effects on iodine formation from KI-starch solutions and ultrasound-induced killing of rat thymocytes
AU - Kondo, Takashi
AU - Nishimura, Jihei
AU - Kitagawa, Hiroshi
AU - Umemura, Shin Ichiro
AU - Tachibana, Katsuro
AU - Toyosawa, Kei Ichiro
N1 - Funding Information:
This research was supported by the Research and Development Committee Program of The Japan Society of Ultrasonics in Medicine. We wish to acknowledge helpful discussions with Dr. Loreto B. Feril, Jr, Department of Radiological Sciences, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan and Dr. Peter Riesz, Radiation Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, U.S.A.
PY - 2003
Y1 - 2003
N2 - We investigated liberation of iodine from solutions of KI-starch and cell lysis of rat thymocytes in argon- and nitrous oxide-saturated aqueous solutions induced by ultrasound at frequencies of 38 and 500 kHz and 1 and 2 MHz. Iodine was liberated in argon-saturated solutions exposed to ultrasound at 38 kHz, 500 kHz, and 1 MHz but not at 2 MHz. Lysis occurred in argon-saturated solutions at all four frequencies, but only at 38 kHz in nitrous oxide-saturated cell suspensions. No iodine was liberated in the other nitrous oxide-saturated samples. Relative ratio of the chemical effect versus 70-percent cell survival (an example of the physical effect) was, in order of frequency, 500 kHz > 1. 0 MHz > 38 kHz > 2.0 MHz. Partial protection was observed for cell lysis and cell viability after sonication with 500 kHz in argon-saturated solution containing cysteamine, a free radical scavenger. These results suggest that the chemical effects of ultrasound are prominent at specific frequencies, and that free radicals induced by ultrasonic cavitation partially affect lysis and the loss of viability of rat thymocytes.
AB - We investigated liberation of iodine from solutions of KI-starch and cell lysis of rat thymocytes in argon- and nitrous oxide-saturated aqueous solutions induced by ultrasound at frequencies of 38 and 500 kHz and 1 and 2 MHz. Iodine was liberated in argon-saturated solutions exposed to ultrasound at 38 kHz, 500 kHz, and 1 MHz but not at 2 MHz. Lysis occurred in argon-saturated solutions at all four frequencies, but only at 38 kHz in nitrous oxide-saturated cell suspensions. No iodine was liberated in the other nitrous oxide-saturated samples. Relative ratio of the chemical effect versus 70-percent cell survival (an example of the physical effect) was, in order of frequency, 500 kHz > 1. 0 MHz > 38 kHz > 2.0 MHz. Partial protection was observed for cell lysis and cell viability after sonication with 500 kHz in argon-saturated solution containing cysteamine, a free radical scavenger. These results suggest that the chemical effects of ultrasound are prominent at specific frequencies, and that free radicals induced by ultrasonic cavitation partially affect lysis and the loss of viability of rat thymocytes.
KW - Cell killing
KW - Chemical effects
KW - Frequency effects
KW - Ultrasonic cavitation
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U2 - 10.1007/BF02481369
DO - 10.1007/BF02481369
M3 - Article
AN - SCOPUS:0042864512
VL - 30
SP - 93
EP - 101
JO - Journal of Medical Ultrasonics
JF - Journal of Medical Ultrasonics
SN - 1344-1388
IS - 2
ER -