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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 229 out of 330
| Title |
Single-Element Transducers |
| Author |
O'Brien WD Jr. |
| Journal |
RadioGraphics |
| Volume |
|
| Year |
1993 |
| Abstract |
A complete understanding of the numerous types of diagnostic ultrasound
(US) transducers starts from a thorough understanding of single-element
circular transducers. This class of transducers provides the basis for understanding fundamentally important concepts such as the piezoelectric effect,
crystal resonance, thickness mode resonance, backing, matching layers, focusing,
and spatial resolution. An understanding of these principles will assist
radiologists in using the full potential of the various diagnostic US transducers. |
| Title |
Sister chromatid exchange analysis of human cells exposed to diagnostic levels of ultrasound. |
| Author |
Martin AO, Madsen EL, Dyer AR, White L, Bouck NP, Sabbagha RE,.Hermanoff M, Chen JM, Ludtke LJ. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
1991 |
| Abstract |
Lymphocyte and lymphoblastoid cells were exposed in vitro to diagnostic levels of ultrasonic.beams delivered by a Hewlett-Packard CE 30001 and a GE system with a 5 MHz linear.transducer for 20 sec, 1 min, 5 min, and 20 min. Temperature and cavitation effects were.controlled and there were matched sham exposures. The synergistic effects of theophylline with.ultrasonography also were investigated. Small increases in sister chromatid exchange levels were.observed after ultrasonic exposure, but increases were so small as to be unlikely to have clinical.relevance. Theophylline was found to have no effect and ultrasonography had no effect on cell.viability. |
| Title |
Sister chromatid exchange and ultrasound. |
| Author |
Goss SA. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
1984 |
| Abstract |
Reported effects of ultrasound on sister chromatid exchange have been contradictory. These studies are discussed and their results, including ultrasonic dosimetry and biologic considerations, are compared. In the few studies showing positive effects, the magnitude was small, and the effects occurred as a result of in vitro exposure. Based on a review of these reports, there does not appear to be sufficient reason to alter presently held views on the safety of clinical ultrasound. |
| Title |
Sister chromatid exchange frequency in human lymphocytes after long duration exposure to pulsed ultrasound. |
| Author |
Barnett SB Barnstable SM Kossoff G. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
1987 |
| Abstract |
The aim of this study is to determine whether sister chromatid exchange (SCE) frequency increases in human lymphocytes that are exposed to pulsed ultrasound conditions within the range typically employed in ultrasound Doppler measurements of fetal blood flow. Whole blood diluted with culture medium was exposed in vitro to 3.1 MHz pulsed ultrasound at spatial peak pulse average (SPPA) intensities from 15 to 135 W/cm2. Insonation for 5 min did not significantly alter the base level frequency of SCEs compared to that observed in sham-insonated controls. To avoid missing an effect, due to differing sensitivities of the division stages within the mitotic cycle, insonation was also applied for 24 hr to include one complete cell division cycle. No change in SCE was observed after this extended insonation at SPPA intensity of 33 W/cm2.
|
| Title |
Sister chromatid exchanges and diagnostic ultrasound.. |
| Author |
Liebeskind D. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1984 |
| Abstract |
No abstract available |
| Title |
Sister chromatid exchanges in Chinese hamster ovary cells exposed to high.intensity pulsed ultrasound: inability to confirm previous positive results. |
| Author |
Miller MW, Azadniv M, Pettit SE, Church CC, Carstensen EL, Hoffman D. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1989 |
| Abstract |
This study was undertaken in an attempt to determine a physical mechanism of action for a recently published report of a small but statistically significant increase in sister chromatid exchanges (SCEs) in Chinese hamster ovary cells exposed to high-intensity pulsed ultrasound. The "positive" report's protocol involved a sizeable chance of ultrasound beam impingement on.the side wall of the cell exposure chamber. Ten experiments per regimen were conducted; the regimens included exposures of (a) chamber center, (b) chamber wall, (c) nine grid sites, 0.5 mm between sites, and (d) nine grid sites, 1.5 mm between sites. The last was an exact replication of the conditions previously reported to induce the small SCE effect. The results did not support the postulate of an increase in SCEs with the ultrasound exposures. |
| Title |
Sister chromatid exchanges in human lymphocytes after exposure to diagnostic ultrasound. |
| Author |
Liebeskind D, Bases R, Mendez F, Elequin F, Koenigsberg M. |
| Journal |
Science |
| Volume |
|
| Year |
1979 |
| Abstract |
The frequency of sister chromatid exchanges increased in freshly isolated human lymphocytes as well as in a continuously growing lymphoblast line by exposure to diagnostic levels of ultrasound for 30 minutes. The results confirm previous findings indicating that ultrasound of diagnostic intensities can affect the DNA of animal cells. |
| Title |
Sister-chromatid exchanges in human lymphocytes exposed in vitro to therapeutic ultrasound. |
| Author |
Ciaravino V, Miller MW, Carstensen EL. |
| Journal |
Mutat Res |
| Volume |
|
| Year |
1986 |
| Abstract |
Human lymphocytes were exposed in vitro to therapeutic levels of ultrasound (1 W/cm2, CW, 0.87 MHz, durations of 80 and 160 sec). There were no significant differences in sister-chromatid exchange frequencies between controls and ultrasound-exposed cells. Exposure of lymphocytes to the positive control.(mitomycin C) resulted in a significant increase in sister-chromatid exchanges. The data do not verify a report by Stella et al. (Mutation Res., 138 (1984) 75-85) that such exposures result in increased frequencies of SCEs. |
| Title |
Sister-chromatid exchanges in mouse embryos after exposure to ultrasound in utero. |
| Author |
Au WW, Obergoenner N, Goldenthal KL, Corry PM, Willingham V. |
| Journal |
Mutat Res |
| Volume |
|
| Year |
1982 |
| Abstract |
Mouse embryos at 2 stages of development were exposed to ultrasound. The bone-marrow cells of the mother, the whole embryo, and the embryonic liver cells were analyzed. There was no consistent increase of sister-chromatid exchanges. Furthermore, the thermal effect of ultrasound did not appear to influence the frequency. Thus, ultrasound doses much higher than those used in clinical diagnosis do not induce cytogenetic damage as assayed by sister-chromatid exchanges. |
| Title |
Skeletal effects of low-intensity pulsed ultrasound on the ovariectomized rodent. |
| Author |
Warden SJ, Bennel KL, Forwood MR, McMeeken JM, Wark JD. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2001 |
| Abstract |
Growing evidence supports low-intensity pulsed ultrasound (US) as an osteogenic mechanical stimulus. Its effects on isolated bone cells and on fractured bone are established. However, its effects on osteoporosis are not clear. This study examined US effects on ovariectomy (OVX) induced bone changes within the rodent hindlimb (distal femur and proximal tibia), and on normal bone in animals following sham-OVX. Animals were exposed to daily unilateral active-US and contralateral inactive-US for 12 weeks. Bone status was assessed using dual energy X-ray absorptiometry and histomorphometry. Ovariectomy resulted in significant bone changes. Low-intensity pulsed US did not influence these changes. These results suggest that the US dose introduced may not be a beneficial treatment for osteoporosis, and that intact bone may be less sensitive to US than fractured bone and isolated bone cells. This may relate to the biophysical mechanisms of action of US, US-bone interactions and tissue level processes taking place. |
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