Endovascular US enhanced vascular gene delivery and increased the efficiency of nonviral platforms to levels previously attained only by adenoviral strategies.

Large numbers of molecules can be delivered intracellularly using low-frequency ultrasound. Both uptake and viability correlate with acoustic energy, which is useful for design and control of ultrasound protocols.

This study provides a quantitative guide to designing ultrasound protocols useful for drug delivery. The acoustic measurements support the hypothesis that ultrasonic cavitation is the mechanism by which membranes are permeabilized. They also suggest that measurable acoustic signals can provide noninvasive, real-time feedback about membrane permeabilization and drug delivery.

It has been hypothesized that one role of the fish’s auditory system may be to detect and localize nearby fish by ‘‘imaging’’ ambient noise scattered by their swimbladders. This is analogous to the role of the visual system of most animals, where the relevant signal is ambient light scattered by objects rather than light emitted by luminous objects. A classical conditioning experiment has been performed which indicates that the fish auditory system is capable of functioning in this manner. The ambient noise was provided by a J-9 transducer driven by Gaussian noise. Scattering of ambient noise by the resonant swimbladder was simulated by applying a filtered version of the same Gaussian noise to a small spherical projector. The target strength and bandwidth of the scattered noise were controlled by the attenuation and passband of the filter. The fish was conditioned to respond to the presence of the signal from the spherical projector. Thresholds of simulated scattered noise as a function of range to the subject were measured for the species Carassius auratus (common goldfish). The fish’s ability to discriminate this signal is taken to be a measure of its ability to detect scattered ambient noise. [Work supported by ONR.]

No abstract

The gas-filled swimbladder of a fish resonates in the ambient noise field, scattering significant amounts of acoustic energy. This characteristic scattered field is thought to assist a fish's own hearing and also may allow for the detection and identification of other scatterers by the receiver [P. H. Rogers et al., J. Acoust. Soc. Am. Suppl. 1 85, S35 (1989)]. The frequency response of the swimbladder can be measured in vivo by a noninvasive vibration amplitude measurement system [M. Cox and P. H. Rogers, J. Vib. Acoust. Str. Rel. Des. 109, 55–59 (1987)]. The response for a variety of fish of the species Carassius auratus (common goldfish) and Astronotus ocellatus (oscar) was measured and correlated with respect to fish size. One aspect of the results further examined was the appearance of twin peaks in the response of some goldfish. X rays of the subjects indicated that differences in size of the anterior and posterior chambers of the swimbladder may be responsible. [Work supported by ONR.]

No abstract

In an earlier paper [P. H. Rogers, J. Acoust. Soc. Am. Suppl. 1 79, S22 (1986)], it was hypothesized that one role of the fish's auditory system may be to detect and localize nearby fish by “imaging” ambient noise scattered by their swim bladders. This is analogous to the role of the visual system of most animals, where the relevant signal is ambient light scattered by objects rather than light emitted by luminous objects. A classical conditioning experiment has been performed which indicates that the fish auditory system is capable of functioning in this manner. The ambient noise is provided by a J-9 transducer driven by Gaussian noise. Scattering of this noise by the resonant swim bladder is simulated by applying a filtered version of the noise signal to a small spherical projector. The “target strength” is bandwidth of the filter. The fish is conditioned to respond to the presence of the signal from the spherical projector. The fish's ability to detect this signal (as a function of range, bearing, etc.) is taken to be a measure of its ability to detect scattered ambient noise.