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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 121 out of 330
| Title |
Experimental studies on the bioeffects of.pulsed ultrasound to the cultured mammalian.cell in vitro.[Article in Japanese] |
| Author |
Tsuzaki T. |
| Journal |
Nippon Sanka Fujinka Gakkai Zasshi |
| Volume |
|
| Year |
1981 |
| Abstract |
Cultured cell originated from human amniotic epithelium was sonicated in 2 HMz.pulsed ultrasound at various intensities for 30-60 min. Cell suspending medium.on sonication was either phosphate buffered saline solution or Eagle's MEM.containing calf serum of 20%. On the evaluation of cell growth suppression,.relative growth ratios, the growth ratios in sonicated groups to control groups.were calculated on 2, 4 and 7 days after sonication. Regression analysis between.these relative growth ratios and spatial average-temporal peak intensities on 4 and.7 days after sonication showed linear correlation. Cell growth suppression.threshold in the period was 246 or 240 mW/cm2 in spatial peak-temporal average.value respectively. On the other hand, intensity measurements in experimental.acoustic field by steel ball method showed that spatial peak values were about.2-5 times as large as spatial average values, and beam width in acoustic field (1.7.cm) was a little broader than the inner diameter of the cell suspending tube (1.2.cm). Cell growth suppression disappeared by elevation of viscosity in the cell.suspending medium, and reappeared by the prolongation of sonication time or.the increment of temporal peak value. |
| Title |
Experimental studies on the effect of ultrasound on mouse embryos. |
| Author |
Shoji R,Momma E,Shimizu T,Matsuda S. |
| Journal |
Teratology |
| Volume |
|
| Year |
1972 |
| Abstract |
Effects of low-intensity ultrasound on mouse embryos of DHS and A/He strains were investigated with special regard to fetal malformation, growth retardation and death. On the 9th day of gestation, pregnant females were exposed to ultrasound waves by the Doppler Fetal detector with a frequency of 2.25Mhz and an acoustic intensity of 40 mW/cm2 for 5 hours.
Features with external anomalies appeared in both experimental and control groups. The difference in frequency of these anomalies between experimental and control groups of A/He mice was statistically significant (p<0.02), but it was insignificant in DHS mice. However, it may be noteworthy that some exencephalous fetuses which were never found spontaneously in both strains occurred in mice of 2 strains exposed to ultrasound waves, although the frequency was low. The incidence of skeletal malformations represented by rib defects in the exposed mice increased significantly as compared with the control mice (p<0.01). Fetal mortality also increased after exposure to ultrasound waves in mice of both strains.
The present result, therefore suggests that the maternal exposure to ultrasound waves induces maldevelopment or intrauterine death in mouse embryos |
| Title |
Experimental studies on the suppression of cultured cell growth curves after irradiation with CW and pulsed ultrasound. |
| Author |
Maeda K, Murao F, Yoshiga T, Yamauchi C, Tsuzaki T. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
1986 |
| Abstract |
Cultured JTC-3 cells of human amniotic cell origin were irradiated with CW ultrasound intensities of 1 W/cm2 (SATA) of more. Cell growth was suppressed when the cells, suspended in phosphate buffered saline, were sonicated while being rotated at 2.5 rpm in a polystyrene tube for 60 min. Dead cells were rarely found after staining and cell colony formation showed no significant decrease. The slow rotation of the cells and the intrinsic nature of the cells may be the reason for this phenomenon. Using the same experimental model, pulsed ultrasound suppressed cell growth at intensities of 240 mW/cm2 (SPTA), 20 W/cm2 (SATP), and 80 mW/cm2 (SPTP) using a pulse duration of 3 ?s and a pulse repetition frequency of 1000 Hz. |
| Title |
Experimental studies on ultrasonic doppler method in obstetrics. |
| Author |
Takeuchi H, Nakazawa T, Kumakiri K, Kusano R. |
| Journal |
Acta Obstet Gynaecol Jpn |
| Volume |
|
| Year |
1970 |
| Abstract |
Although many reports have been made concerning clinical use of ultrasonic Doppler method for the detection of fetal heart beat, only the results of clinical applications using commercial apparatuses were described. In this report, studies on fundamental and clinical experiments using a newly developed Doppler apparatus for detection of fetal heart beat were carried out. Combined use of ultrasound tomography and Doppler method confirmed the ability of this apparatus to obtain a characteristic Doppler signal representing the pulsation of the circulatory system of the fetus. Detection of fetal life with transabdominal and transvaginal approaches could be done from the 7th week of pregnancy to term in 436 normal pregnancy cases. Localization of placenta using placental signal was also studied. Animal experiment on the safety of the ultrasonic continuous wave for the Doppler method was carried out, and no harmful effect was found. |
| Title |
Experimental studies relative to the therapeutic use of ultrasound. |
| Author |
Herrick JF, Janes JM, Ardan NI Jr. |
| Journal |
JAVMA |
| Volume |
|
| Year |
1956 |
| Abstract |
No abstract available. |
| Title |
Experimental study of diffraction and waveguide effects in ultrasonic attenuation measurements. |
| Author |
Carome EF, Witting JM, Fleury PA. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1961 |
| Abstract |
An experimental study has been made of the propagation of ultrasound in liquids under both free-field and guided-wave conditions. Free-field measurements have been made from 1 to 20 Mc in low absorbing liquids, employing both circular and square sound sources. These measurements indicate that the correction for diffraction loss predicted by existing theories is applicable only so long as this loss is smaller than the true absorption. Attenuation measurements also have been made in liquids confined in various cylindrical and rectangular metallic waveguides. For a given configuration, the observed variation with path length of the attenuation follows closely that predicted theoretically for propagation in a solid sample of the same dimensions. Some consideration is given to possible sources of this result which differs somewhat from the predictions of current theories. |
| Title |
Experimental study of the effects of Optison concentration on sonoporation in vitro. |
| Author |
Ward M, Wu J, Chiu JF. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2000 |
| Abstract |
Lethal sonoporation and reparable sonoporation were observed in Jurkat lymphocytes in suspension with the addition of varying amounts of Optison, a commercially available bubble-based contrast agent. For given ultrasound (US) exposure conditions (spatial peak-pressure amplitude of 0.2 MPa, duty cycle 10% and 2-MHz frequency), sonoporation was directly related to the bubble-to-cell ratio (in a range from 0 to 230). It was found that the nearest bubble-cell spacing was also related to the occurrence frequency of bioeffects. A constant bubble-to-cell ratio often provided very different results for two different initial cell concentrations (200,000 cells/mL and 600,000 cells/mL), with the higher cell concentration generally exhibiting higher levels of sonoporation. In contrast, a constant bubble-to-cell spacing provided similar results between the two initial cell concentrations. The frequency of reparable and lethal sonoporation was seen to decay as the inverse-cube power of the nearest bubble-cell spacing. Significant reparable sonoporation was observed at a bubble-cell spacing that was 10 microm larger than the minimum spacing at which significant lethal sonoporation was observed. Preliminary analysis also suggests the possibility of a step-wise increase in lethal sonoporation as spacing decreases; further experiment is needed. |
| Title |
Experimental teratology of ultrasound exposure in animals. |
| Author |
Shimizu T,Tanaka K. |
| Journal |
Rep Res Grant Prev Phys Ment Disabil |
| Volume |
|
| Year |
1980 |
| Abstract |
Pregnant Chinese hamsters were exposed to the used ultrasound of USP-1 generator (2Mhz, 3μsec, repetition 1KHz,SATA 200mW/cm2,SATP 67 W/cm2) for 5 min on days of 8,9 and 10 of the gestation. Lower intensities were also used in the experiment. The animals received hysterotomy in day 18. No increase of fetal anomaly was observed in the groups exposed to ultrasound. |
| Title |
Experimental validation of the spectral fit algorithm using tissue mimicking phantoms. |
| Author |
Bigelow TA, O'Brien WD Jr. |
| Journal |
Acoust Imaging |
| Volume |
|
| Year |
2006 |
| Abstract |
Characterizing tissue by measuring its physical properties has potential for improving the diagnostic capabilities of medical ultrasound. One parameter that is estimated using the power spectrum of backscattered ultrasound echoes is the characteristic size or correlation length of the tissue microstructure responsible for the scattering. Unfortunately, the characteristic size measurement has traditionally been corrupted by uncertainties in the frequency-dependent attenuation along the propagation path. Recently, this problem was addressed by estimating the characteristic size and attenuation along the propagation path simultaneously using an algorithm termed the Spectral Fit (SF) algorithm. Using computer simulations to study the SF algorithm, the accuracy and precision of the attenuation estimate improved as the frequency range (largest frequency minus smallest frequency used by the algorithm when obtaining estimates) was increased. Similarly, the accuracy and precision of the scatterer size estimates were improved as the Δka eff (largest wavenumber times scatterer radius minus smallest wavenumber times scatterer radius used by the algorithm) was increased. In this study, the simulation results were validated using a tissue mimicking phantom. The phantom had an attenuation of 0.83 dB/cm-MHz with glass beads with a radius range between 22.5 and 26.5 μm at a concentration of 47.7/mm3. The SF algorithm accurately estimated the size of the glass beads and the precision of the size and attenuation estimates improved with increasing Δka eff and frequency range respectively in the same manner as was observed in the simulation studies. |
| Title |
Experimental verification of the sectored annular phased array for MRI guided ultrasound surgery. |
| Author |
Fjield T. Hynynen K. |
| Journal |
Proc IEEE Ultrason Symp |
| Volume |
|
| Year |
1996 |
| Abstract |
To meet two of the requirements for MRI Guided Ultrasound Surgery, namely small surgical equipment and large focal volumes, a combined array encompassing the design parameters of the concentric-ring array and the sector-vortex array has been proposed. Simulations will show that the sectored annular array is capable of producing larger necrosed tissue volumes than the concentric-ring alone, while maintaining the ability of the concentric-ring array to move the focal volume in the axial direction of the array. These simulations are verified by measurements of the acoustic fields produced by an experimental array in water. In addition, the constructed array produced the necessary power required to coagulate tissue in rabbit thigh in vivo, while the temperature elevation was monitored using MRI. |
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