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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 102 out of 330
| Title |
Effect of ultrasound on trematode cercariae. |
| Author |
Farrell RK, Watson RE, Lloyd M. |
| Journal |
J Parasitol |
| Volume |
|
| Year |
1973 |
| Abstract |
No abstract available |
| Title |
Effectiveness of lipid microbubbles and ultrasound in declotting thrombosis. |
| Author |
Xie F,Tsutsui JM,Lof J,Unger EC,Johanning J,Culp WC,Matsunanga T,Porter TR. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2005 |
| Abstract |
The objectives of this study were to determine the effectiveness of lipid-encapsulated microbubbles and ultrasound (US) in recanalizing arteriovenous graft thrombi and the effect that tissue attenuation has on the success rate. A total of 55 thrombotic occlusions were created in four canines. The thrombosed grafts were randomly treated with two different 1-MHz US intensities, low (0.4 to 0.6 W/cm2) and high (10 W/cm2). Intragraft microbubbles were compared with intragraft saline and with the same dose of microbubbles given IV. IV microbubbles were also given both in the presence and absence of a tissue-mimicking phantom. High-intensity US (10 W/cm2) with intragraft microbubbles produced significantly higher patency and flow scores than did US with saline (p < 0.01). US with IV microbubbles had higher success rates in recanalizing thrombosed grafts than did US alone at all intensities. Attenuation reduced the rate at which successful recanalization occurred at both low and high intensities. US and microbubbles are capable of recanalizing acute arteriovenous graft thromboses. Higher intensities may be needed in the presence of tissue attenuation. |
| Title |
Effects of acoustic insonation parameters on ultrasound contrast agent destruction. |
| Author |
Yeh CK, Su SY. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2008 |
| Abstract |
Ultrasound contrast agents (UCAs) are used to enhance the acoustic backscattered intensity of blood and thereby assist the assessment of blood perfusion. Characterization of UCA destruction provides important information for the design of contrast-assisted perfusion imaging. High-speed optical observation of single microbubble destruction during acoustic insonation has been performed in previous studies. The results identified that pressure, center frequency and transmission phase have significant effects on the fragmentation threshold. We proposed an acoustic-based experiment method to demonstrate the relationship between different acoustic exposure conditions and the degree of UCA destruction. The method also provides a simple and convenient way to determine the microbubble destruction threshold. The experiments introduced three insonation parameters, including acoustic pressure (0 to 1 MPa), pulse frequency (1, 2.25, 5 and 7.5 MHz) and pulse length (1 to 10 cycles). The term of surviving percentage (SP) was proposed to represent the ratio of UCA backscattered power with and without acoustic insonation. The results showed that the SP decreased with decreasing pulse frequency, but with increasing transmission acoustic pressure and pulse length. In addition, there was an exponential relationship between SP and acoustic pressure, and thus the UCA destruction pressure threshold could be predicted from the fitted exponential curve. The results also show that the degree of UCA destruction was not related to mechanical index (MI). Potential applications of this method include UCA high-resolution destruction/replenishment imaging model, microbubble cavitation, sonoporation in drug delivery and gene therapy. |
| Title |
Effects of airborne ultrasound on man. |
| Author |
Knight JJ. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
1968 |
| Abstract |
No abstract available.. |
| Title |
Effects of cavitation on ultrasonic cleaning. |
| Author |
Scheiberle PL. |
| Journal |
Rep Univ Ill - Urbana/Champaign Dept Theor Appl Mech |
| Volume |
|
| Year |
1993 |
| Abstract |
The cleaning of particle, enamels, grease, and viscoelastic thin films is shown to be attributed to cavitation bubbles. An albumin-dirt solution, nail enamel, grease, and latex paint were used to simulate these different materials. All the substances were capable of being removed from a surface using ultrasonic cavitation, although the paint and dirt mixture were easier to remove than the nail enamel and the grease. The paint samples had more cleaning when tap water was used, two transducers were implemented, the transducers were closer together, and when the slide was closer to the transducer. The grease samples had more cleaning when the transducers were closer together, the slide was closer to the tranducer, and when higher temperatures (above 30?C) were used. Mechanical mechanisms for the cleaning of the grease and paint samples include: cavitation bubbles acting on a flaw in the coating, cavitation bubbles striking the surface of the coating, and the growth of trapped vapor in the coatings due to ultrasound. |
| Title |
Effects of continuous and pulsed ultrasound on scar tissue in rats. |
| Author |
Han Y-YL. |
| Journal |
Thesis(MS): Virginia Commonwealth Univ |
| Volume |
|
| Year |
1973 |
| Abstract |
No abstract available. |
| Title |
Effects of CW and pulsed ultrasound on the immune response in mice. |
| Author |
Pham Thi The L, Hrazdira I, Skorpikova J. |
| Journal |
Scr Med |
| Volume |
|
| Year |
1988 |
| Abstract |
No abstract available. |
| Title |
Effects of diagnostic ultrasound irradiated during foetal stage on emotional and cognitive behaviour in rats. |
| Author |
Murai N, Hoshi K, Kang CH, Suzuki M. |
| Journal |
Tohoku J Exp Med |
| Volume |
|
| Year |
1975 |
| Abstract |
Our previous work demonstrated that the prenatally irradiated ultrasound of even a low-intensity might affect the functional development of the brain of offspring in rats. In the present study, in order to investigate the emotional and cognitive.behaviour of offspring of rats that received the irradiation of a diagnostic ultrasound on the 9th day of gestation, the following three experiments were carried out: 1) The emotional reactivity of the offspring was measured by the open-field technique. 2) The same reactivity was further evaluated in terms of the excape response from electroshock. 3) The cognitive function of the offspring was assessed through the discrimination learning and the discrimination reversal learning. The offspring of irradiated rats showed significantly more distinct vocalization response to handling in the open-field test and significantly more distinct escape response from the electroshock, when compared with the two control rats (untreated control and sham-irradiated control). From these findings it may be suggested that the emotional behaviour in rats can be influenced by a low-intensity ultrasound irradiated during foetal stage. On the other hand, as for the cognitive behaviour, the results of the present study suggest no adverse effect on it. |
| Title |
Effects of diagnostic ultrasound irradiated.during fetal stage on development of orienting.behavior and reflex ontogeny in rats. |
| Author |
Murai N, Hoshi K, Nakamura T. |
| Journal |
Tohoku J Exp Med |
| Volume |
|
| Year |
1975 |
| Abstract |
The physical growth, the development of orienting behavior and neuromotor reflexes.of offspring of rats that received an irradiation of a diagnostic level of ultrasound on.the 9th day of gestation were estimated and compared with those of two control.groups (untreated control and sham-irradiated or immobilized control). Results.showed no significant group differences in terms of either physical development or.development of orienting behavior. In the reflexological tests, however, a number of.those reflexes that developed after 6 days of postnatal life of the offspring of.irradiated rats showed significant delays in maturation when compared with those of.the untreated control rats, but showed no difference from those of the sham-irradiated.group. From these findings it is suggested that under certain circumstances such as in.stress, the prenatally irradiated ultrasound of even a low-intensity may affect the.development of the brain of offspring. |
| Title |
Effects of divalent cations on the ultrasonic absorption coefficient of negatively charged liposomes (LUV) near their phase transition temperature. |
| Author |
Ma LD, Magin RL, Dunn F. |
| Journal |
Biochim Biophys Acta |
| Volume |
|
| Year |
1987 |
| Abstract |
The ultrasonic absorption coefficient per wavelength (alpha lambda), as a function of temperature and frequency, was determined for large unilamellar vesicles (LUV) in the vicinity of their phospholipid phase transition temperature, using a double crystal acoustic interferometer. (The vesicles were composed of a 4:1 (w/w) mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG). It has been found that alpha lambda reaches a maximum (alpha lambda)max at the phase transition temperature (tm) of the phospholipids in the bilayer, at an ultrasonic relaxation frequency of 2.1 MHz. Divalent cations (Ca2+ and Mg2+), added to LUV suspensions, shifted (alpha lambda)max to higher temperatures, dependent upon the concentration of divalent cation. It was also found that the shape of the alpha lambda versus t curve was significantly changed, representing changes in the Van't Hoff enthalpy of the transition, and therefore, the cooperative unit of the transition. This suggests that divalent cations interact individually with the negatively charged phospholipid headgroups of DPPG and with DPPC headgroups, thus decreasing the cooperative unit of the transition. The observed upward shift in tm suggests an interaction that increases the activation energy and, therefore, the temperature of the phase transition. However, alpha lambda as a function of frequency did not change with the addition of divalent cations and, thus, the relaxation time of the event responsible for the absorption of ultrasound is not changed by the addition of divalent cations. |
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