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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 162 out of 330
| Title |
Killing of Drosophila larvae by the fields of an electrohydraulic lithotripter. |
| Author |
Carstensen EL, Campbell DS, Hoffman D, Child SZ, Ayme-Bellegarda EJ. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1990 |
| Abstract |
Drosophila larvae contain small gas bodies stabilized within their respiratory system. Because these bubbles are inhibited in their capacity to expand by the surrounding tissues, it is probable that they do not respond to acoustic fields in the manner.described by classical cavitation theory that assumes a spherical bubble in an infinite fluid. However, just because of this inhibited expansion, they may serve as reasonable models for the gas bodies in mammalian tissues. Approximately one half of a population of Drosophila larvae is killed by exposure to 3 to 10 double lithotripter shocks with a positive pressure of 2-3 MPa. In contrast with the predictions of classical cavitation theory, adding a negative pressure to the exposure has little influence on the killing rate or its threshold pressure. The available evidence suggests that interaction of gas bodies in tissues with pressure fields and the resultant biological effects may be qualitatively different than predicted by classical cavitation theory and that positive rather than negative pressure may be a predictor of these effects. |
| Title |
Killing of drosophila larvae by the fields of an electrohydraulic lithotripter. |
| Author |
Carstensen EL, Campbell DS, Hoffman D, Child SZ, Ayme-Bellegarda EJ. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1990 |
| Abstract |
Drosophila larvae contain small gas bodies stabilized within their respiratory system. Because these bubbles are inhibited in their capacity to expand by the surrounding tissues, it is probable that they do not respond to acoustic fields in the manner described by classical cavitation theory that assumes a spherical bubble in an infinite fluid. However, just because of this inhibited expansion, they may serve as reasonable models for the gas bodies in mammalian tissues. Approximately one half of a population of Drosophila larvae is killed by exposure to 3 to 10 double lithotripter shocks with a positive pressure of 2–3 MPa. In contrast with the predictions of classical cavitation theory, adding a negative pressure to the exposure has little influence on the killing rate or its threshold pressure. The available evidence suggests that interaction of gas bodies in tissues with pressure fields and the resultant biological effects may be qualitatively different than predicted by classical cavitation theory and that positive rather than negative pressure may be a predictor of these effects. |
| Title |
Lack of bioeffects of ultrasound energy after intravenous administration of FS069 (Optison) in the anesthetized rabbit. |
| Author |
Killam AL, Greener Y, McFerran BA, Maniquis J, Bloom A, Widder KJ, Dittrich HC. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
1998 |
| Abstract |
The current study was designed to provide a sensitive in vivo model to maximize the potential bioeffects (measured by hemolysis) of B-mode ultrasound energy in combination with FS069 (Optison). B-mode ultrasound energy was delivered to anesthetized male New Zealand white rabbits with a phased array 5 MHz transducer on a Hewlett-Packard Sonos 1500 ultrasonograph, with transmit level set to maximum (40 dB, approx 135 W/cm2). FS069 (Optison), latex particles in human albumin, or human albumin alone (vehicle) was infused via an ear vein at 0.6 mL/kg. No statistically significant changes were noted in serum free hemoglobin or lactate dehydrogenase either over time or between groups. |
| Title |
Lack of effect of continuous wave ultrasound exposure on in vivo Chinese hamster cheek pouch epithelial mitotic index. |
| Author |
Miller MW, Church CC, Cox C. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1988 |
| Abstract |
Chinese hamster cheek pouches were everted and the epithelia exposed in vivo for 1 min to continuous wave 1.07 MHz ultrasound at intensities ranging from 0.5 to 10.0 W cm-2. Since the mitotic index of the hamster epithelium exhibited a circadian rhythm, the times of sonication and tissue sampling were arranged to allow for detection of a division delay as evidenced by a change in mitotic index in cells.insonated in the early S or late S/early G2 phases of the cell cycle. There was no demonstrated effect of the ultrasound exposures on mitotic index. |
| Title |
Lack of effect of high-intensity pulsed ultrasound on sister chromatid exchange and in vitro Chinese hamster ovary cell viability. |
| Author |
Ciaravino V, Miller MW, Carstensen EL, Dalecki D. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1985 |
| Abstract |
The frequency of sister chromatid exchanges (SCEs) in in vitro Chinese hamster ovary cells and their viability were not affected by 3-min exposures to 2-4 MHz, focused, pulsed ultrasound with a pulse repetition rate of 200 Hz, pulse duration of.10 mu sec and intensities (SPTP) of 500 W/cm2 and 2500 W/cm2. The viability results are consistent with those reported elsewhere; the SCE response does not verify a specific previously reported positive response. |
| Title |
Lack of effect of pulsed ultrasound on ABO antigens of human erythrocytes in vitro. |
| Author |
Miller DL, Lamore BJ, Boraker DK. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1986 |
| Abstract |
The efficacy of pulsed ultrasound in removing ABO blood group antigens from human erythrocytes was investigated in vitro. Cell suspensions were exposed to 5.25 MHz focused ultrasound with 1.23 microseconds pulses, at 0, 20, and 37 degrees C using spatial peak, pulse average intensities of 11, 126, and 1000 W/cm2 and pulse spacings of 10, 100, and 1000 microseconds. A second experiment involved application of 7.5 MHz pulses of 0.77 microseconds duration and 8 W/cm2 SPPA intensity which were spaced 1.25 ms apart. Exposed.cells were tested for agglutination by antibody to determine changes in antigen expression. In addition, supernates from exposed cells were tested for the presence of soluble antigen. A sensitive capillary tube agglutination technique was developed for these experiments. No detectable antigen removal occurred as a result of any of the pulsed ultrasound exposures as compared to sham exposures. A positive control, which employed antigenic material prepared from cells disrupted by ultrasonic cavitation, indicated that the assay could detect the soluble antigen equivalent of about one cell in 10,000. |
| Title |
Lack of induced increase in sister chromatid exchanges in human lymphocytes exposed to in vivo therapeutic ultrasound. |
| Author |
Miller MW, Azadniv M, Cox C, Miller WM. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1991 |
| Abstract |
In 1984 Stella et al. reported that each of 10 patients exposed to therapeutic ultrasound had a statistically significant increase in sister chromatid exchanges (SCEs) at mid- and end of therapy; there was a wide range of clinical symptoms (e.g., elbow epicondylitis to knee arthrosis) in this set of patients. In the present study, a set of 4 patients each with some diagnosis recommending therapeutic ultrasound was similarly tested for SCE induction; an additional set of 4 healthy persons underwent sham-therapeutic ultrasound exposures. For both sets of subjects (patients, nonpatients) there was no increase in the frequency of SCEs. |
| Title |
Lack of ultrasound effect on in vitro human lymphocyte sister chromatid exchange. |
| Author |
Brulfert A, Ciaravino V, Miller MW. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1984 |
| Abstract |
The frequency of sister chromatid exchanges (SCEs) in human lymphocytes cultured in vitro was not affected by a 30 min exposure to a 2.25 MHz focused ultrasound beam (from a clinical diagnostic unit with a pulse repetition rate of 1000 Hz, a 1 mu sec burst duration, and a 2-200 W/cm2 maximum intensity). A 30 sec exposure to continuous wave 1 MHz 2 W/cm2 (SP) ultrasound from an experimental device lysed 10-15% of the lymphocytes; there was no increase in SCEs in the survivors relative to unexposed controls. Treatment of lymphocytes with 0.033 micrograms/ml mitomycin-C, a known SCE inducer, increased the frequency of SCEs about 4 times above control levels. |
| Title |
Lamb waves in piezoelectric focused radiator as a reason for discrepancy between O'Neil's formula and experiment. |
| Author |
Cathignol D, Sapozhnikov OA, Zhang J. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1997 |
| Abstract |
One of the well-known methods of ultrasound focusing is the use of a transducer having the form of a concave spherical cap. In the theoretical analysis O'Neil's formula is widely used, which describes acoustic pressure on the axis of the transducer under the assumption that normal velocity of its surface is uniform. Usually, it is believed that modern piezoelectric focused sources are very close to this theoretical model. The paper presented describes results of experimental investigation which showed that there exists a significant disagreement between the observed acoustic field and that predicted by the theory of O'Neil. Two types of measurements have been made to clarify this problem. The acoustic pressure field of a focused piezoelectric transducer (with aperture diameter of 100 mm, radius of curvature of 100 mm, resonance frequency of 1 MHz) has been measured in a water tank using a miniature hydrophone. In addition, the radiator surface vibration has been studied in air using an optical interferometric technique. Theoretical analysis and the measurements show that the disagreement between the theory and the experiment is due to Lamb waves, which originate at the radiator edge, propagate along the piezoceramic plate without significant attenuation, and thus radiate additional acoustic perturbations. |
| Title |
Laminar submerged jets by color Doppler ultrasound: A model of the ureteral jet phenomenon. |
| Author |
Summers RM, Adler RS, Fowlkes JB, Rubin JM. |
| Journal |
Invest Radiol |
| Volume |
|
| Year |
1992 |
| Abstract |
RATIONALE AND OBJECTIVES. The authors developed and tested a technique to noninvasively measure ureterovesical junction (UVJ) pressure gradients. Such a technique could be used to evaluate ureteral reflux and obstruction. METHODS. Color Doppler ultrasound measurements of an in vitro model of the ureteral jet were performed. RESULTS. The authors show that the orificial rate of momentum transfer of the ureteral jet (from which the intraluminal pressure in the ureter can be calculated) can be determined to within 45% to 94% of its true value depending primarily on the flow sensitivity of the color flow imager. Marked improvement in the momentum calculation (> 80%) is achieved when a low-flow sensitivity is used. CONCLUSION. Such noninvasive measurements could replace more invasive techniques (eg, the Whitaker test or cystoscopy with or without ureteral cannulation), which seriously perturb the system of interest.
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