Physical acoustics, Vol. 14
1981; Elsevier BV; Volume: 19; Issue: 2 Linguagem: Inglês
10.1016/0041-624x(81)90115-3
ISSN1874-9968
Autores Tópico(s)Ultrasound and Cavitation Phenomena
ResumoWhilst heating is an important mechanism for in vivo irradiation it can be eliminated in the nonabsorbing medium of in vitro cell suspension. (Love & Kremkau, 1980). Also the use of short pulses and the absence of plane strong reflectors minimise standing wave effects. Even when present their damaging effects are apparently mediated by cavitational activity.In vitro mechanisms of interaction which have been clearly identified involve gas bubble activation, where radiation pressure forces attract cells to oscillating bubbles (Nyborg, 1982) and acoustic microstreaming fields disrupt cells.The only in vitro studies showing repeatable effects from diagnostic pulsed conditions employed a cavitation phenomenon as in the formation of platelet aggregation (Miller et al., 1979; Barnett and Kossoff, 1984) and killing of Drosophila larvae (Child and Carstensen, 1981) and eggs (Child and Carstensen, 1982).Unconfirmed effects of diagnostic intensities have been reported on the cell surface (reduced attachment, abnormal surface activity, immunological changes, electrophonetic activity), on the nucleus (sister chromatid exchanges) or on cell locomotion.Examples of implausible reports of bioeffects from diagnostic ultrasound were given as: platelet damage from in vivo insonation (Sanada, 1977); and erythrocyte osmolarity changes, from ultrasound during labour (Bause et al., 1983).In vitro exposures tend to enhance cavitation mechanisms (Ciaravino et al., 1981). In vitro cavitation may result in the effect of released chemicals from lysed cells (e.g. Williams and Miller, 1980). Investigators should be encouraged to include an additional control incubated with a small amount of homogenised cells.Other proposed mechanisms include the biological effect of free radicals in the medium which may be liberated as a result of cavitational activity during pulses of diagnostic ultrasound (Riesz, 1985).
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