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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 260 out of 330
| Title |
The influence of contrast agents on hemorrhage produced by lithotripter fields. |
| Author |
Dalecki D, Raeman CH, Child SZ, Penney DP, Mayer R, Carstensen EL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1997 |
| Abstract |
Ultrasonic contrast agents greatly increase the side effects of low-amplitude lithotripter fields in mice. Using a piezoelectric lithotripter, adult mice were exposed to 200 lithotripter pulses with a peak positive pressure amplitude of 2 MPa. During the exposure period, mice were injected with approximately 0.1 mL of the ultrasonic contrast agent Albunex. For comparison, another group of mice experienced the same lithotripter exposures, but were not injected with contrast.agent. Following exposures, animals were sacrificed and observed for hemorrhage in various organs and tissues. Mice exposed to the lithotripter field alone had minimal hemorrhage only in the intestine and lung. In comparison, mice injected with Albunex during exposure exhibited extensive hemorrhage in the intestine, kidney, muscle, mesentery, stomach, bladder, seminal vesicle and.fat. |
| Title |
The influence of hematocrit on hemolysis by.ultrasonically activated gas-filled micropores. |
| Author |
Miller DL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1988 |
| Abstract |
In vitro studies of ultrasonic bioeffects typically employ cell number densities much lower than those present in vivo, which can lead to difficulties in.interpretation and extrapolation. In this study, the influence of cell number density on the hemolytic effect of ultrasonic gas-body activation (a low-level.form of cavitation) was investigated. Hydrophobic membranes with 4 micron diameter gas-trapping micropores were immersed in saline suspensions of erythrocytes with hematocrits (HCT) from 0.001 to 0.3, and whole blood, and exposed to 1.7 MHz continuous-wave ultrasound in a 37 degrees C saline-filled.exposure bath. Significant hemolysis was observed for spatial peak intensities.above about 45-90 mW/cm2 for the 16 min exposures. The percentage of cells.hemolyzed tended to decrease with increasing hematocrit such that the number.of cells hemolyzed, which is proportional to the product of the hematocrit and.the percent hemolysis, remained roughly constant. Readily observable in vitro.effects may therefore become quite subtle when diluted, as for in vivo conditions, by large numbers of cells. |
| Title |
The influence of ovarian sonication on fetal development in the rat. |
| Author |
Garrison BM, Bo WJ, Krueger WA, Kremkau FW, McKinney WM. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1973 |
| Abstract |
This study was undertaken to determine whether sonication of the ovaries on day 8 of pregnancy would alter fetal development in the rat. Mating was confirmed by the presence of sperm (day 1 of gestation) in the vaginal smear, and the rats were grouped and treated on day 8 as follows: Group I (controls) had both ovaries surgically exposed to sonic gel for 10 min/ovary; group II received 10 watts/cm2 temporal peak intensity of pulsed ultrasound through the body wall for 10 min/ovary; group III received 100 watts/cm2 in a similar manner as group II; group IV was treated the same as group III except the ultrasound was applied directly to the surgically exposed ovaries. The frequency employed was 1.9 mHz. The animals were sacrificed on days 15-17, implantation sites and resorptions were counted, and fetal viability was determined. There were no statistically significant differences in the percentage of resorptions among any of the groups. The data indicated that the ovaries were functional with regard to fetal development. |
| Title |
The influence of ultrasound and temperature on the cochlear microphonic response following a round window irradiation. |
| Author |
Barnett SB. |
| Journal |
Acta Otolaryngol (Stockh) |
| Volume |
|
| Year |
1980 |
| Abstract |
Impairment of cochlear function was investigated following ultrasonic irradiation of the vestibule and the cochlea through the round window in cats and guinea pigs. Selective destruction of the vestibular balance mechanism with negligible impairment of cochlear microphonic response was achieved, provided that the ultrasound beam was directed away from the cochlea and towards the ampulla of the superior semicircular canal. Directing ultrasound into the cochlea produced a depression in C.M. which was greatest in the higher frequency responsive area corresponding to the region of the first two cochlear turns. The degree of cochlear microphonic depression increased as the duration of irradiation was extended. The occurrence of a significant temperature increase accompanying the application of ultrasound implicated the involvement of a thermal mechanism in addition to the mechanical disruptive effect of ultrasound. |
| Title |
The influence of ultrasound frequency and gas-body composition on the contrast agent-mediated. enhancement of vascular bioeffects in mouse intestine. |
| Author |
Miller DL, Gies RA. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2000 |
| Abstract |
The induction by ultrasound (US) of petechiae and hemorrhages in mouse intestine was examined with injection of gas body-based contrast agents. Production of petechiae in the intestinal wall was enhanced by contrast agents for both continuous and pulsed (10 micros pulses repeated at 1 kHz) exposure relative to a gas body-free blank. For pulsed exposure with 10 mL/kg of Albunex, apparent thresholds for peak negative pressure amplitude were 0.42 MPa at 0.4 MHz, 0.85 MPa at 1.09 MHz and 2.3 MPa at 2.4 MHz. Results at these frequencies were the same for 10-11 cycle pulses with fixed duty cycle (0.01). Thresholds for hemorrhage into the intestinal lumen were not appreciably enhanced by added Albunex, and appear to be compatible with previously reported lithotripsy data when duty factor differences are considered. The agents PESDA, Optison and Levovist had lower thresholds (for example, 1.8 MPa for Levovist) than Albunex at 2.3 MHz, and yielded more petechiae. The thresholds for petechiae induction by US with contrast agents encroach upon the exposure range relevant to diagnostic US practice. |
| Title |
The influence of ultrasound on embryonic development. |
| Author |
Barnett SB. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1983 |
| Abstract |
The chick embryo provides a convenient experimental subject to assess the effects of ultrasound on a developing biological system. Insonating the whole embryo prior to organogenesis with spatial peak temporal average intensities of 4.5 W/cm2 pulsed, and 100 W/cm2 continuous wave focused, produced no lethal effect or observable developmental changes during three days following the treatment. Any bio-effect which may have resulted from the interaction of ultrasound at the cellular level was not severe enough to bring about irreversible gross physical abnormalities in the developing embryo. The effects of standing waves or other extraneous physical factors were considered to be greatly reduced by irradiating embryos "in ovo" rather than in glass dishes following explantation. |
| Title |
The influence of ultrasound on the heart muscle of the rat on the basis of histological investigations. |
| Author |
Jankowiak J, Hasik J, Majewski C. |
| Journal |
N/A |
| Volume |
|
| Year |
1958 |
| Abstract |
No abstract available. |
| Title |
The influence of ultrasound on the reaction of immobilized enzymes. |
| Author |
Rosenfeld E, Schmidt P. |
| Journal |
Arch Acoust |
| Volume |
|
| Year |
1984 |
| Abstract |
The effect of ultrasonic waves in the MHz range on the activity of immobilized alpha-amylase and glucoamylase was investigated. Measurements of the catalytic efficiency were carried out in a flow cell, in dependence on the concentration, the flow rate, and the molecular weight of the substrate, as well as on the size of the carrier particles (porous polystyrene). The results show that the ultrasonic effect might be explained by the promotion of the diffusion processes predominately within the Nernst diffusion layer of the carrier beads. |
| Title |
The influence of variations in biophysical conditions on hemolysis near ultrasonically activated gas-filled micropores. |
| Author |
Miller DL, Thomas RM. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1990 |
| Abstract |
Hemolysis induced by 1.9-MHz ultrasound in 0.5% suspensions of canine erythrocytes with 3.7-microns-diam micropore-trapped gas bodies was investigated for a variety of biophysical conditions. For isotonic media, hemolysis increased with exposure duration (4-64 min) but did not greatly change with exposure temperature (15, 25, 37, and 48 degrees C), or prior heat treatment (48 or 50 degrees C for 30 min). The temperature results were especially interesting because increased temperatures might have been expected to increase the sensitivity of the cells to the ultrasonically activated gas bodies. Variations in osmolarity (180, 290, or 580 mOsm) had little influence on the results. Increasing the viscosity (0.7, 2.2, 2.3, or 4.2 cP) of the medium decreased the effect, and this did not seem to depend on the molecular weight of the dextran additive (9400 or 250,000). A medium with elevated mass density (1.12 g/cm3) seemed to increase the effectiveness of the exposures. This.condition eliminated the density difference between the cells and the medium, and might have been expected to reduce the effectiveness of the exposures, because the radiation force, which theoretically gathers cells to the gas bodies, is minimized for such conditions. This information should aid in developing refinements to the theoretical understanding of low-intensity ultrasonic bioeffects. |
| Title |
The inner temperature of the eye after the effect of ultrasound [Article in German]. |
| Author |
Hrazdira I, Preisova J, Anton M. |
| Journal |
Albrecht Von Graefes Arch Klin Exp Ophthalmol |
| Volume |
|
| Year |
1967 |
| Abstract |
No abstract available. |
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