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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 152 out of 330
| Title |
Indirect effect of ultrasound on water.permeability of the connective tissue. |
| Author |
Pospisilova J |
| Journal |
Experientia |
| Volume |
|
| Year |
1964 |
| Abstract |
No abstract available |
| Title |
Indirect measurement of blood pressure using Doppler-shifted ultrasound. |
| Author |
Kardon MB, Stegall HF, Stone HL, Bishop VS, Ware RW, Kemmerer WL. |
| Journal |
Dig 7th Int Conf Med Biol Eng - Stockholm |
| Volume |
|
| Year |
1967 |
| Abstract |
Arterial blood pressure usually cannot be determined by conventional sphygmomanometry in infants or in adults suffering from hypotensive shock. Small or constricted vessels apparently do not generate Korotkoff sounds loud enough to be heard with a stethoscope. We have found that a method directly which can sense arterial motion directly, using a Doppler ultrasonic principle first suggested by Ware, is sensitive enough to measure systolic and diastolic blood pressures even in these two difficult situations. |
| Title |
Induction of base damage in DNA solutions by ultrasonic cavitation. |
| Author |
Fuciarelli AF, Sisk EC, Thomas RM, Miller DL. |
| Journal |
Free Radic Biol Med |
| Volume |
|
| Year |
1998 |
| Abstract |
Ultrasound can damage macromolecules by the mechanical (shearing) and sonochemical (free radical generating) action of ultrasonic cavitation. Attributing macromolecular damage to either direct mechanical stress or to indirect mechanisms involving free radicals or other sonochemicals is a challenging problem. DNA damage induced by ultrasound was evaluated by measuring the formation of purine and pyrimidine products using combined gas chromatography-mass spectrometry with selected ion monitoring. Samples of DNA were prepared in 10 mmol dm-3 phosphate buffered saline (pH 7.4) and saturated with a mixture of argon:oxygen (3:1). Continuous 2.17 MHz ultrasound exposures at 0.82 mPa spatial peak negative pressure amplitude were performed in a 60 rpm rotating tube exposure system. Hydrogen peroxide yields were measured after each exposure to quantify the cavitation activity and ranged up to 350 mumol dm-3 for 1-h exposures. Purine and pyrimidine products identified were those typically observed following exposure of DNA to hydroxyl radical-generating systems, such as ionizing radiation, hypoxanthine/xanthine oxidase, or hydrogen peroxide in the presence of transition metal ions. The yields of these products were directly correlated with cavitation activity as measured by residual hydrogen peroxide concentrations. The yields of DNA products increased in the following order: thymine glycol approximately cytosine glycol > 8-oxoAde > FAPyAde approximately 5-HMU approximately 5,6-diOHCyt > FAPyGua. Unexpectedly, 8-oxoguanine did not exhibit a dose-dependent increase above background levels, and this observation is inconsistent with processes involving metal ion-dependent formation of hydroxyl radicals from hydrogen peroxide. In addition, the product yields were far too large to result from the residual hydrogen peroxide. Thus, ultrasonic cavitation appears to have a mode of action distinct from either ionizing radiation or formation of hydroxyl radicals via Fenton-like reaction with transition metals. |
| Title |
Induction of transplantable malignant tumours in mice by repeated short exposures to continuous wave (25 kHz) ultrasound. |
| Author |
Sur P, Chatterjee SN. |
| Journal |
Curr Sci |
| Volume |
|
| Year |
1998 |
| Abstract |
No abstract available. |
| Title |
Inertial cavitation produced by pulsed ultrasound in controlled host media. |
| Author |
Deng CX, Xu Q, Apfel RE, Holland CK. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1996 |
| Abstract |
The purpose of this work is to provide measurements in well-characterized media in order to better understand inertial (transient) cavitation phenomena. Focused transducers with megahertz center frequencies (2.5 MHz, 4.3 MHz) and a clinical diagnostic ultrasound system (4.0 MHz) was used to generate pulsed ultrasound to induce cavitation. An improved active cavitation detector which utilizes a highly focused transducer with much higher center frequency (30 MHz) was used to measure the threshold of inertial cavitation. In order to study the effect of the concentration of nucleation agents on cavitation thresholds, experiments were conducted in distilled water seeded with polystyrene particles. Inertial cavitation thresholds were measured for various concentrations of polystyrene particles. It was observed that the threshold decreased from 2.5 MPa at concentration of about 10(6) particles/ml to 1.6 MPa at a concentration of about 10(9) particles/ml. The effect of the concentration is not significant for smaller changes of concentration. Measurements of the cavitation thresholds were then made in specially developed phantom materials to study the effect of viscosity on the cavitation threshold when surface tension and other mechanical properties of the materials are kept relatively constant. Experimental results show that the threshold increases with increasing viscosity, consistent with theoretical predictions. Cavitation was also detected in water seeded with polystyrene particles using a clinical ultrasound system at an acoustic pressure of 3.84 MPa. Results are comparable with those obtained in the laboratory using a 4.3-MHz focused transducer. |
| Title |
Influence of changing pulse repetition frequency on chemical and biological effects induced by low-intensity ultrasound in vitro. |
| Author |
Buldakov MA, Hassan MA, Zhao QL, Feril LB Jr, Kudo N, Kondo T, Litvyakov NV, Bolshakov MA, Rostov VV, Cherdyntseva NV, Riesz P. |
| Journal |
Ultrason Sonochem |
| Volume |
|
| Year |
2009 |
| Abstract |
This study was undertaken to examine ultrasound (US) mechanisms and their impact on chemical and biological effects in vitro as a function of changing pulse repetition frequency (PRF) from 0.5 to 100Hz using a 1MHz-generator at low-intensities and 50% duty factor (DF). The presence of inertial cavitation was detected by electron paramagnetic resonance (EPR) spin-trapping of hydroxyl radicals resulting from sonolysis of water. Non-cavitational effects were evaluated by studying the extent of sucrose hydrolysis measured by UV spectrophotometry. Biological effects were assessed by measuring the extent of cell killing and apoptosis induction in U937 cells using Trypan blue dye exclusion test and flow cytometry, respectively. The results indicate significant PRF dependence with respect to hydroxyl radical formation, cell killing and apoptosis induction. The lowest free radical formation and cell killing and the highest cell viability were found at 5Hz (100ms pulse duration). On the other hand, no correlation was found between sucrose hydrolysis and PRF. To our knowledge, this is the first report to be devoted to study the impact of low PRFs at low-intensities on US-induced chemical and biological effects and the mechanisms involved. This study has introduced the role of "US streaming" (convection); a forgotten factor in optimization studies, and explored its importance in comparison to standing waves. |
| Title |
Influence of contrast agent dose and ultrasound exposure on cardiomyocyte injury induced by myocardial contrast echocardiography in rats. |
| Author |
Miller DL, Li P, Dou C, Gordon D, Edwards CA, Armstrong WF. |
| Journal |
Radiology |
| Volume |
|
| Year |
2005 |
| Abstract |
PURPOSE: To detect specific cardiomyocyte injury induced by myocardial contrast material-enhanced echocardiography (ie, myocardial contrast echocardiography) in rats and to ascertain the influences of contrast material dose and ultrasound exposure on this injury.
MATERIALS AND METHODS: All animal procedures were approved by the university committee for the use and care of animals. Myocardial contrast echocardiography with 1:4 electrocardiographic (ECG) triggering was performed at 1.5 MHz in 61 anesthetized rats. Evans blue (EB) dye was injected as the vital stain for cardiomyocyte injury. At the start of myocardial contrast echocardiography, which lasted 10 minutes, perflutren lipid microsphere-based contrast material was infused through the tail vein for 5 minutes. Premature heartbeats were counted from the ECG record. The numbers of EB-stained cells counted on sections of heart specimens obtained 24 hours after myocardial contrast echocardiography and then either fresh frozen or embedded in paraffin were determined by using fluorescence microscopy. Results were compared statistically by using t tests and Mann-Whitney rank sum tests.
RESULTS: EB-stained cells were concentrated in the anterior region of the myocardium. In the paraffin-embedded specimens, EB-stained cells were often accompanied by but largely separate from areas of inflammatory cell infiltration. At end-systolic triggering with a 50 microL/kg dose of microsphere contrast material, the EB-stained cell count increased with increasing peak rarefactional pressure amplitude, with significantly increased cell counts at 1.6 MPa (P < .02) and 2.0 MPa (P < .005) relative to the cell counts at sham myocardial contrast echocardiography. Premature heartbeats had a similar exposure-response relationship; however, number of premature heartbeats and EB-stained cell count did not appear to be directly related (coefficient of determination r2 = 0.03). The EB-stained cell counts at end-diastolic triggering were not significantly different from those at end-systolic triggering (P > .1). EB-stained cell counts increased with increasing contrast material dose, from 10 to 50 microL/kg, at 2.0 MPa.
CONCLUSION: Cardiomyocyte injury was induced by the interaction of ultrasound pulses with contrast agent microbubbles during myocardial contrast echocardiography in rats, and the numbers of injured cells increased with increasing contrast agent dose and ultrasound exposure. |
| Title |
Influence of CW-ultrasound on ultrastructure of preimplantation mouse embryos cultured in vitro. |
| Author |
Dvorak M, Hrazdira I, Stastna J, Skorpikova J. |
| Journal |
Scr Med |
| Volume |
|
| Year |
1987. |
| Abstract |
No abstract available. |
| Title |
Influence of density, elasticity, and structure on ultrasound transmission through trabecular bone cylinders. |
| Author |
Cavani F, Giavaresi G, Fini M, Bertoni L, Terlizzi F, Barkmann R, Cane V. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
2008 |
| Abstract |
The aim of this in vitro study is to evaluate the potentiality of quantitative ultrasound (QUS) to separate information on density, elasticity, and structure on specimens of trabecular bone. Fifteen cylinders of spongy bone extracted from equine vertebrae were progressively demineralized and subjected to QUS, micro computed tomography (muCT), Dual energy X-ray absorptiometry (DXA) at various mineralization levels. Eventually all cylinders underwent a compression test to calculate the Young's modulus. Correlation analysis shows that speed of sound (SOS) is strictly associated to bone mineral density (BMD), Young's modulus, and all muCT parameters except for degree of anisotropy (DA). Fast wave amplitude (FWA) is directly correlated with bone surface and total volume ratio (BS/TV) and trabecular separation (Tb Sp), and inversely correlated with trabecular number (Tb N). Because muCT parameters were strictly correlated to BMD and Young's modulus data, partial correlation analysis was performed between SOS, FWA, and structural and elastic data in order to eliminate the effect of density. SOS was significantly correlated to bone volume and total volume ratio (BV/TV), BS/TV, and Young's modulus, and FWA was significantly correlated to Tb Sp only. These results show that SOS is strongly influenced by volumetric mineral bone density and elastic modulus of the specimen, and FWA is mainly affected by trabecular separation independently on density. Therefore, SOS and FWA are able to provide different and complementary information, at least on trabecular bone samples. |
| Title |
Influence of dissolved gases on chemical and biological effects of ultrasound. |
| Author |
Kondo T, Kuwabara M, Sato F, Kano E. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1986 |
| Abstract |
The influence of dissolved gases (O2, Ar, N2O, and CO2) on the chemical and biological effects of 1.2 MHz continuous wave ultrasound was investigated. Spin-trapping of OH and H radicals with 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) and observation of iodine liberation from a potassium iodide-starch solution were employed for monitoring the chemical effects, while lysing of mouse L5178Y cells was employed for monitoring the biological effects. The effectiveness of the dissolved gases in producing OH-DMPO adducts and H-DMPO adducts was O2 > Ar > N2O = CO2 ≈ O and Ar > O2 = N2O = CO2 ≈ O, respectively. A result similar to the yield of OH-DMPO was obtained from the liberation of iodine induced by ultrasound. In addition, the effectiveness of the dissolved gases in lysing mouse L5178Y cells by ultrasound was O2 =Ar > N2O = CO2 ≈ O. These results suggest that both dissolved N2O and CO2 gases in solution suppressed not only the chemical effect but also the biological effect. |
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