Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
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William D. O'Brien, Jr. publications:

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Title Reproducible subcellular alterations in hepatocytes resulting from ultrasound.
Author Stephens RJ, Hart CP, Torbit CA, Edmonds PD.
Journal Ultrasound Med Biol
Volume
Year 1980
Abstract Reproducible ultrastructural alterations in subcellular organelles have been produced with ultrasonic exposure. Mitochondria appear to be the most sensitive organelle, exhibiting swelling, electron-dense condensations in the matrix, loss of cristae, and the formation of lamellar membranes, with eventual disruption of the outer membrane. The endoplasmic reticulum is less sensitive, but also shows a graded response to increasing exposure including dilation of the cisternae, loss of ribosomes from the surface, and vesiculation. Lysosomes appear to retain their structural integrity better than other cytoplasmic organelles. If the level of exposure is not lethal to the cell, most of the changes are repaired within 96 hr; however, mitochondrial changes persist for longer periods and may be irreversible. Additional studies are needed to understand the mechanism of mitochondrial injury and recovery.


Title Research in cancer therapy with ultrasound.
Author Kremkau FW.
Journal Proc Ultrason Symp IEEE
Volume
Year 1977
Abstract The potential use of ultrasound in cancer therapy has been studied by several investigators over a period of 45 years. There have been three approaches to the subject: studies of effects on tumors with (1) ultrasound alone, (2) ultrasound in combination with radiotherapy, and (3) ultrasound in combination with chemotherapy. In area (1), varying results have been reported. In some cases, decreased growth rates or regressions of tumors have been reported, but with others, no effect was observed or growth rate was increased. In area (2), for some animal tumors, combined treatment gave a greater effect on the tumors than that produced by x-ray alone, while in others, addition of ultrasound produced no change. In area (3), drug enhancement has been observed in melanoma and in mouse tumor cells treated with ultrasound and several anticancer drugs. Mechanisms of action in these experiments are not fully known. The potential of ultrasound to provide local tumor control or enhancement of other therapy modes motivates the current effort by several groups to further study and understand its action on malignancies.


Title Research support for diagnostic ultrasound.
Author Nyborg WL.
Journal J Clin Ultrasound
Volume
Year 1974
Abstract No abstract available.


Title Resistance of CHLF hamster cells to ultrasonic radiation of 1-5 MHz frequency.
Author Bleaney BI, Blackbourn P, Kirkley J.
Journal Br J Radiol
Volume
Year 1972
Abstract Concentrated suspensions of CHLF hamster cells in small polythene containers were exposed to 1-5 MHz ultrasound. Continuous wave and pulsed irradiation was used under conditions in which there was no evidence of stable cavitation occurring in the samples. When the temperature of the cells remained below 45?C, no reduction in survival was observed with intensities up to 8-8 W/cm(2) of continuous radiation for one hour, or with peak intensities of 15-0 W/cm(2) of pulsed radiation. Thus, no direct effect of ultrasonic irradiation on cell reproductive integrity has been demonstrated.


Title Resolution performance of Doppler ultrasound flowmeters.
Author Griffith JM, Brody WR, Goodman L.
Journal J Acoust Soc Am
Volume
Year 1976
Abstract Ultrasonic Doppler flowmeters can simultaneously obtain spatial and velocity distribution patterns of flow in a blood vessel. The factors fixing spatial and velocity resolution, however, must be determined if optimum utilization is to be realized. The parameters influencing spatial resolution have been described in the literature, but velocity resolution has received relatively little attention. This paper demonstrates analytically how optimum velocity resolution can be derived with a simple mathematical model and presents experimental data to verify theory. In addition, a "resolution product" is offered which characterizes pulsed Doppler flowmeters. This product shows explicitly the necessary compromise between position and velocity resolution for a given instrument.


Title Resonance frequencies of lipid-shelled microbubbles in the regime of nonlinear oscillations.
Author Doinikov AA, Haac JF, Dayton PA.
Journal Ultrasonics
Volume
Year 2009
Abstract Knowledge of resonant frequencies of contrast microbubbles is important for the optimization of ultrasound contrast imaging and therapeutic techniques. To date, however, there are estimates of resonance frequencies of contrast microbubbles only for the regime of linear oscillation. The present paper proposes an approach for evaluating resonance frequencies of contrast agent microbubbles in the regime of nonlinear oscillation. The approach is based on the calculation of the time-averaged oscillation power of the radial bubble oscillation. The proposed procedure was verified for free bubbles in the frequency range 1-4 MHz and then applied to lipid-shelled microbubbles insonified with a single 20-cycle acoustic pulse at two values of the acoustic pressure amplitude, 100 kPa and 200 kPa, and at four frequencies: 1.5, 2.0, 2.5, and 3.0 MHz. It is shown that, as the acoustic pressure amplitude is increased, the resonance frequency of a lipid-shelled microbubble tends to decrease in comparison with its linear resonance frequency. Analysis of existing shell models reveals that models that treat the lipid shell as a linear viscoelastic solid appear may be challenged to provide the observed tendency in the behavior of the resonance frequency at increasing acoustic pressure. The conclusion is drawn that the further development of shell models could be improved by the consideration of nonlinear rheological laws.


Title Response characteristics of a finite aperture, phase sensitive ultrasonic receiver based upon the acoustoelectric effect.
Author Busse LJ, Miller JG.
Journal J Acoust Soc Am
Volume
Year 1981
Abstract The acoustoelectric effect (i.e., the interaction of ultrasound with conduction electrons in a piezoelectric semiconductor) provides the basis for the construction of a finite aperture, phase insensitive receiver using a single crystal of cadmium sulfide. In this paper we present a formalism describing the operation of such a receiver. Criteria for the optimization of the device in terms of ultrasonic bandwidth, response time, sensitivity, and electrical and mechanical loading are presented. In an accompanying paper [J. Acoust. Soc. Am. 70, 1377-1386 (1981)], we discuss and demonstrate the merits of using a phase insensitive receiver when measurements of a phase distorted (spatially noncoherent) ultrasonic radiation must be made.


Title Response of bubbles to diagnostic ultrasound: a unifying theoretical approach.
Author Hilgenfeldt S, Lohse D, Zomack M.
Journal Eur Phys J B
Volume
Year 1998
Abstract The scattering of ultrasound from bubbles of 1 micrometer radius, such as used in contrast enhancers for ultrasound diagnostics, is studied. We show that sound scattering and "active" emission of sound from oscillating bubbles are not contradictory, but are just two different aspects derived from the same physics. Treating the bubble as a nonlinear oscillator, we arrive at general formulas for scattering and aborption cross-sections. We show that several well-known formulas are recovered in the linear limit of this ansatz. In the case of strongly nonlinear oscialltions, however, the cross-sections can be larger than those for linear response by several orders of magnitude. The major part of the incident sound energy is then converted into emitted sound, unlike what happens in the linear case, where the absorption cross-sections exceed the scattering cross-sections.


Title Response of contrast agents to ultrasound.
Author Sboros V.
Journal Adv Drug Deliv Rev
Volume
Year 2008
Abstract Microbubbles are used as ultrasonic contrast agents that enhance the ultrasound signals of the vascular bed. The recent development of site-targeted microbubbles opened up the possibility for molecular imaging as well as localised drug and gene delivery. Initially the microbubbles' physical properties and their response to the ultrasound beam were not fully understood. However, the introduction of fast acquisition microscopy has allowed the observation of the microbubble behaviour in the presence of ultrasound. In addition, acoustical techniques can determine the scatter of single microbubbles. Sonoporation experiments promise high-specificity drug and gene delivery, but the responsible physical mechanisms, particularly for in vivo applications, are not fully understood. An improvement of microbubble technology may address variability related problems in both imaging and drug/gene delivery.


Title Response of multicell spheroids to 1-MHz ultrasonic irradiation: Cavitation-related damage.
Author Sacks PG, Miller MW, Sutherland RM.
Journal Radiat Res
Volume
Year 1983
Abstract The response of EMT6/Ro single cells and multicell spheroids (150-800.microns diameter) to 1-MHz ultrasonic irradiation was determined for.intensities of 0-5 W/cm2 for 1-5 min. Damage was assessed by evaluating.both lysis and survival of individual spheroid cells, growth of whole.spheroids, and the physical integrity of whole spheroids by histological and.scanning electron microscopic techniques. The surviving fraction of spheroid.cells was higher than that of single cells, and several of the intensity-duration.combinations showed a statistically significant correlation between resistance.to ultrasound and increased spheroid size. This resistance with size was also.found in spheroid growth experiments. Histological sections showed that.both peripheral and internal damage occur. The relationship of spheroid.damage to studies of effects on tissues and possible therapeutic use of.nonthermal ultrasound are discussed.


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