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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 292 out of 330
| Title |
Ultrasonic induction of sister chromatid exchanges in human lymphocytes. |
| Author |
Haupt M, Martin AO, Simpson JL, Iqbal MA, Elias S, Dyer A, Sabbagha RE. |
| Journal |
Hum Genet |
| Volume |
|
| Year |
1981 |
| Abstract |
We analyzed sister chromatid exchange (SCE) frequencies as an indicator of DNA damage induced in human lymphocytes by 'real-time' ultrasound. A range of exposure times and intensities was tested in a series of blind, randomized, in vitro experiments under spatial and sonographic conditions simulating exposure of a gravid abdomen and uterus. Our studies showed small but consistent effects of ultrasound on SCE frequencies, for each experiment. Differences between matched control and exposed means were significantly different from zero. chi 2 tests for homogeneity indicated no significant differences among either the means or the total distributions of the controls, nor among each of the separate dose levels. Consequently, experiments were pooled, and chi 2 analysis indicated significant differences both among distributions and among means of SCE frequencies for controls versus exposed cells (P less than 0.001). The pooled control mean was also significantly different from each of the pooled dose means. Correcting for multiple comparisons gave identical results for the paired comparisons of means except for the 20-min level which was borderline (0.025 less than P less than 0.01). We conclude that the well-established value of clinical ultrasonography warrants its continued use; however, minimizing the numbers and lengths of exposure per patient would seem prudent, pending further information on clinical implications of our results. |
| Title |
Ultrasonic investigations of the relaxation processes related to the presence of the group --C(0) (NH) in molecules. |
| Author |
Bartynowska-Meus Z, Juszkiewicz A. |
| Journal |
Arch Acoust |
| Volume |
|
| Year |
1983 |
| Abstract |
Measurements of the velocity and the absorption coefficient of ultrasound were taken in monosubstituted amides as a function of temperature and frequency. It was found that a single relaxation process related to rotation of molecules around the C - N bond occurs over the temperature and frequency range investigated. Termodynamic parameters which characterize the process observed were determined. |
| Title |
Ultrasonic irradiation of enzyme solutions. |
| Author |
Macleod RM, Dunn F. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1966 |
| Abstract |
It is shown that inactivation of enzymes in solution by 3-MHz ultrasound in the intensity range 1-3 W/cm2, which has been reported by other investigators, is, in fact, due to the presence of rubber materials used as part of the containing vessel during the experiments. |
| Title |
Ultrasonic irradiation of mammalian cells in vitro at hyperthermic temperatures. |
| Author |
ter Haar G, Stratford IJ, Hill CR. |
| Journal |
Br J Radiol |
| Volume |
|
| Year |
1980 |
| Abstract |
Suspensions of V79 cells and HeLa cells have been irradiated with continuous 3 MHz ultrasound at a spatial average intensity of 3W cm-2. This irradiation condition did not give rise to cell lysis. When the cells were irradiated with ultrasound for up to.six hours at 37 degrees C no cell killing was observed. However, at temperatures in the hyperthermia range 42--45 degrees C the increase in cell killing that resulted from the irradiation was greater than that which could be attributed to its heating effect alone. |
| Title |
Ultrasonic irradiation of mouse tissues in vivo and human amniotic cells in vitro. |
| Author |
Adamovics A, Edmonds PD. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1981 |
| Abstract |
Recently published results have been substantiated by enlarging the group sizes of mice subjected to whole-body exposure for 200s and of human amniotic cells in vitro for 2000s at 34 C. Spatial average intensity was 1 W/cm2. Cyclic AMP, cyclic GMP and histamine in moues skin, lung and peritoneal cells, and cAMP and cGMP in human amniotic cells were assayed as sensitive indicators of membrane damage. No significant effect of ultrasound was observed. Statistical analysis indicates an 80% probability that we would have detected a difference in the means for exposed and sham exposed groups if it had been greater than one standard deviation in 9 out of 18 comparisons for mouse tissues and 7 out of 8 comparisons for human amniotic cells. |
| Title |
Ultrasonic irradiation of the central nervous system at high sound levels. |
| Author |
Fry WJ, Dunn F. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1956 |
| Abstract |
High level ultrasound produces, under properly controlled dosage conditions, selective changes in the central nervous system. The physical mechanism of the action of the sound requires elucidation. Some of the problems associated with determining the physical mechanism are discussed and a preparation and procedure are described which are appropriate for accurately determining dosage relations for such a study. The quantitative results obtained with this preparation are presented. |
| Title |
Ultrasonic irradiation of the guinea pig labyrinth correlation of morphology and intralabyrinthine temperature. |
| Author |
Lundquist PG, Schindler RA, Stahle J. |
| Journal |
Acta Otolaryngol |
| Volume |
|
| Year |
1978 |
| Abstract |
The effects of high frequency ultrasound on the inner ear structures after irradiation of the lateral.semicircular canal have been analysed by means of light-and electronmicroscopy. Sudden as well.as gradual morphological changes in the vestibular sensory epithelium are described. Damage to.the connective tissue stroma, blood vessels and nerve fibres characterized the chronic phase..Both cochlear morphology and hearing remained normal after irradiation of some behaviorally.conditioned animals. The temperature rise in the labyrinth during continuous irradiation was.studied. The experiments indicated that the mechanical effects may be more significant than the.thermal in explaining the structural changes of the inner ear of guinea pigs. The results are.compared with previous extensive experience of ultrasound treatment of patients with Meniere's disease. |
| Title |
Ultrasonic light diffraction patterns in ethylene in the critical region. |
| Author |
Sliwinski AS, Brown AE. |
| Journal |
Acustica |
| Volume |
|
| Year |
1965/66 |
| Abstract |
The technique for studying the propagation of ultrasound in a medium by examining the diffraction of a light beam is applied to ethylene near its critical point. The observed fringe pattern differs from that in a non-critical medium, exhibiting fluctuations of intensity in each order and a characteristic asymmetry of orders. The changes in the diffraction pattern with time have been photographed and the fluctuations in several diffraction orders noted over periods of 30 s. The statistical distribution of the light intensity level have been examined in each case and are characterised by (1) the deviation of the observed distribution from a normal one and (2) the standard deviation of the normal distribution closest to that observed. Both these parameters increase with approach to the critical point. The fluctuations show a cyclic variation from sharpness to diffuseness with an approximate period of 0.5 s. |
| Title |
Ultrasonic measurement of glomerular diameters in normal adult humans. |
| Author |
Hall TJ, Insana MF, Harrison LA, Cox GG. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1996 |
| Abstract |
The average size of acoustic scatterers and the integrated backscatter coefficient of kidney cortex were measured in vivo from 2-4 MHz for a group of 50 normal adult. volunteers. The authors' goal was to determine the sensitivity of the ultrasonic measurements under clinical conditions by identifying biologic sources of estimation. uncertainty. Based on 10 measurements on each kidney of each volunteer, the average glomerular diameter for the group was found to be 216 +or- 27 micrometer (SD).. Glomerular size was found to correlate with body surface area (r=0.4), and the ratio of glomerular surface area to body surface area (GSA/BSA) was found to be constant. throughout normal adult life with GSA/BSA=(8.24 +or- 1.35)*10(sup -8) (SD). These results are consistent with histologic analyses found in the literature. Within an. individual, 7% standard errors in GSA/BSA are typical. Biologic variability dominates the variance in scatterer size estimates in a group not matched for BSA, where it. accounts for 47% of the variance. In a group of individuals matched for BSA, biologic variability accounts for only 21% of the variance; day-to-day variability accounts. for 35% of the variance; and experimental parameters account for the remainder. If a deviation greater than 2*SD is considered abnormal, then this technique can. potentially detect changes in glomerular diameter as small as 30 mu m within an individual. To detect abnormal GSA/BSA values for an individual, GSA/BSA would have. to differ from the mean for that group by about 3.6*10(sup -8) or about 40%. Therefore, at this time scatterer size estimates appear most reliable for tracking the. progression of disease and treatment for an individual over time. |
| Title |
Ultrasonic measurement of infant blood pressure. |
| Author |
Massie HL, Ziedonis JG, Black I. |
| Journal |
Med Instrum |
| Volume |
|
| Year |
1973 |
| Abstract |
Blood pressure determined by aortic catheterization in 19 neonates and infants ranging in age from 2 weeks to 13 months and weighing 5 to 11 pounds was compared with brachial arterial blood pressure as measured by Doppler-shifted reflected ultrasound from the moving artery wall in order to evaluate accuracy. A specially designed cuff and a transducer assembly with common transmit and recieve crystals was used. The mean systolic difference was -2.48 mmHg, SD 1.99, correlation coefficient 0.994. For diastolic pressure, the mean difference was 2.37 mmHg, SD 2.37, correlation coefficient 0.980. |
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