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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 257 out of 330
| Title |
The effects of industrial airborne ultrasound on humans. |
| Author |
Acton WI. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1974 |
| Abstract |
Reported physiological effects resulting from the exposure of small animals to ultrasound cannot be transposed directly to man. There is no evidence of permanent biological changes, including hearing loss, as a result of normal industrial exposures to pure ultrasound, although some effects may occur as a result of experimental laboratory exposures. The high levels of high-frequency audible sound which accompany many industrial processes, particularly those producing cavitation, may cause unpleasant subjective effects, including headaches, nausea, tinnitus, and possibly fatigue in persons without hearing loss at those frequencies. |
| Title |
The effects of prenatal ultrasound exposure on postnatal growth and acquisition of reflexes. |
| Author |
Jensh RP, Lewin PA, Poczobutt MT, Goldberg BB, Oler J, Brent RL. |
| Journal |
Radiat Res |
| Volume |
|
| Year |
1994 |
| Abstract |
The examination of pregnant women using diagnostic ultrasound has increased greatly over past decades in the United States. As sonography techniques have been altered and refined, there has been renewed interest concerning possible effects on the developing fetus, since exposures in mid-gestation occur during the sensitive period of brain development. The present study is concerned with possible neonatal functional deficits due to exposure of the fetus to ultrasound. An ultrasound exposure tank was designed specifically for controlled studies of bioeffects. Thirty-six pregnant rats were anesthetized, immersed to the axilla in a water tank and exposed on the 15th, 17th and 19th days of gestation. Twelve rats were exposed to 5.0 MHz pulsed ultrasound of effective pulse duration equal to approximately 0.170 microseconds, pulse repetition rate 1 kHz, and a spatial.peak, temporal peak intensity (ISPTP) of 500 W/cm2, representing a clinically relevant exposure level. The spatial peak, pulse average intensity (ISPPA), spatial peak temporal average intensity (ISPTA) and maximum intensity (Im) were determined to be 100 W/cm2, 24 mW/cm2 and 230 W/cm2, respectively. The maximum rarefaction pressure, pr, was measured as 12.5 x 10(5) Pa, and the total power was 2.5 mW. Twelve other rats were exposed to 1500 W/cm2, ISPTP (ISPPA, 350 W/cm2; ISPTA, 58 mW/cm2; Im, 600 W/cm2). Twelve additional rats were sham-exposed. Since the focal area was about 0.5 cm2, computer-controlled stepper motors moved the rats through the ultrasound field to assure uniform exposure of the abdominal/pelvic region. Total exposure time was 35 min. Additionally, a miniature thermocouple was implanted in a few rats to verify that no significant increase in body temperature took place during exposure. All neonates were subjected to five reflex tests and observed for four physiological parameters. Postnatal growth also was monitored. Analyses of the data indicate there were no significant alterations in neonatal development or postnatal growth due to exposure to 5.0 MHz ultrasound below an intensity (ISPTP) of 1500 W/cm2. Studies continue to be completed at higher exposure levels to determine the margin of safety, and the animals will continue to be monitored and evaluated through young adulthood to determine if there are long-term behavioral effects due to fetal exposure to ultrasound. . |
| Title |
The effects of pulsed ultrasound on the fetus. |
| Author |
Carstensen EL, Gates AH. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
1984 |
| Abstract |
Recent developments suggest that transient cavitation must be considered in assessing the safety of diagnostic uses of ultrasound. An analysis of the literature on exposure of the fetus to pulsed ultrasound reveals no direct evidence that.diagnostic ultrasound produces any effect on the fetus. |
| Title |
The effects of some physical factors on the production of hyperthermia by ultrasound in neoplastic tissues. |
| Author |
Hynynen K, Watmough DJ, Mallard JR. |
| Journal |
Radiat Environ Biophys |
| Volume |
|
| Year |
1981 |
| Abstract |
A one-dimensional and a three-dimensional computer model have been built in order to study the importance of blood flow and ultrasonic absorption in tissues during local hyperthermia. The decreased blood flow in the interior of certain tumours and possibly the increased ultrasonic absorption of the malignant tissue in some cases may cause selectively higher temperatures inside the tumours though the heat input is the same as in the surrounding tissues. Also, the vasodilation of.blood vessels in normal tissues as a response to heat causes a therapeutically useful temperature difference. These blood flow differences can lead to enhanced effects during sonication to produce hyperthermia in the tumour. The inhomogeneity of blood flow in the tumour causes a non-uniform temperature distribution leaving the well-perfused cells in the advancing front at a much lower temperature than the cells in the necrotic centre. Thus, the combination of local hyperthermia with radio-and chemotherapy seems to offer the most attractive means of destroying malignant tissue. |
| Title |
The effects of ultrasonic activation of gas bodies in Elodea leaves during continuous and pulsed irradiation at 1 MHz. |
| Author |
Miller DL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1977 |
| Abstract |
Leaves of the aquatic plant Elodea, which contain gas-filled intercellular channels, were irradiated at 1 MHz in pulsed and continuous modes. Morphological perturbations of the leaf cells include disruption of the parietal layer leading to cell death, when leaves are irradiated at spatial-and-temporal-peak intensities above a threshold I(sub)0. Although the cellular organelles are fragmented at intensities well above I(sub)0, no structural changes were found in the organelles, as observed by electron microscopy, in cells which had not been lethally injured. The presence of gas bodies prior to irradiation leads to values of I(sub)0 below the threshold for cavitation and cell death in the absence of these bodies. For continuous-irradiation times t in the range 10(exp)-3 to 10(exp)4 sec, I(sub)0 is proportional to t(exp)-0.29 and is about 2.4 W/cm2 for 1 sec irradiations. For pulsed irradiations, the effects of individual pulses accumulate to yield values of I(sub)0 below those for single-pulse irradiations. The values of I(sub)0 for pulsed irradiations are equal to, or greater than, those for continuous irradiations of equal total on-time. |
| Title |
The effects of ultrasound and 6-chloropurine on the growth of krebs-2 ascites tumor cells. |
| Author |
Piscitelli J. |
| Journal |
Thesis(MS): Catholic Univ of America |
| Volume |
|
| Year |
1961 |
| Abstract |
No abstract available. |
| Title |
The effects of ultrasound in vivo on mouse liver in contact with an aqueous coupling medium. |
| Author |
Martin CJ, Gregory DW, Hodgkiss M. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1981 |
| Abstract |
Liver tissue of anaesthetised mice, exposed by dissection, has been treated while bathed in salin with therapeutic intensity levels of ultrasound for periods up to 2 min. Samples of tissue were taken on completion of the irradiations and prepared for light and electron microscope examination. Specimens irradiated with 0.8 MHz ultrasound contained patches of damaged tissue several hundred microns across at depths of up to 2 mm below the incident surface. In specimens treated with 1.5 MHz ultrasound, the surface few hundred microns of issue was modified, and after 3 MHz irradiation no changes were found. When the abdominal wall covered the liver surface, no effects were observed at any frequency. The lowest intensity at which damage occurred was the same as that at which acoustic emission associated with cavitation events occurring in the saline surrounding the liver. |
| Title |
The effects of ultrasound of varying frequencies on rat liver. |
| Author |
Taylor KJ, Pond J. |
| Journal |
J Pathol |
| Volume |
|
| Year |
1970 |
| Abstract |
No abstract available. |
| Title |
The effects of ultrasound on chromosomes, nuclei and other structures of the cells in plant tissues. |
| Author |
Lehmann JF, Herrick JF, Krusen FH. |
| Journal |
Arch Phys Med Rehabil |
| Volume |
|
| Year |
1954 |
| Abstract |
No abstract available. |
| Title |
The effects of ultrasound on circulation. |
| Author |
Dyson M, Pond JB. |
| Journal |
Physiotherapy |
| Volume |
|
| Year |
1973 |
| Abstract |
No abstract available. |
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