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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 111 out of 330
| Title |
Enhancement of contractility in rat isolated papillary muscle with therapeutic ultrasound. |
| Author |
Forester GV, Roy OZ, Mortimer AJ. |
| Journal |
J Mol Cell Cardiol |
| Volume |
|
| Year |
1982 |
| Abstract |
In an earlier report from our laboratory, we described some changes in the mechanical activity of rat isolated papillary muscles exposed to therapeutic ultrasound. With ultrasound intensity at 1.0 W/cm2 (1 MHz) we noted a significant depression of resting or diastolic force without a concomitant alteration of the developed force. We attributed this change to nonthermal effects of the irradiation since temperature compensated controls did not show the same effect. Those experiments were performed at a temperature of 26 C and a stimulation rate of 3 pulses/min. In the present experiments, we describe the effects of therapeutic ultrasound on rat isolated pappilary muscles stimulated to contract at rates between 6 and 360/min at a temperature of 30 C under both normal and hypoxic/acidotic conditions. In all cases, we induced a significant increase in the developed force of muscles exposed to the ultrasound for a 5 min period. |
| Title |
Enhancement of DNA synthesis in neonatal mouse tibial epiphyses after exposure to therapeutic ultrasound.. |
| Author |
Elmer WA, Fleischer AC. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1974 |
| Abstract |
In vitro growth of tibiae removed from newborn mice was monitored after treatment with ultrasound. Bones, in an acoustically uniform medium, were insonated with continuous-wave ultrasound at a frequency of 1.0 MHz with an intensity of 1.8 W/cm2. Contralateral isolates were used as controls. Purely thermal effects were held to a minimum. A statistically insignificant increase in elongation was observed after three five-minute exposures 24 hours apart. A similar response was also found for protein accumulation and radioactive proline incorporation into protein in the cartilaginous epiphyses. However, after three exposures of ultrasound the incorporation of radioactive thymidine into DNA was significantly stimulated. |
| Title |
Enhancement of fibrinolysis with 40-kHz ultrasound. |
| Author |
Suchkova V, Siddiqi FN, Carstensen EL, Dalecki D, Child S, Francis CW. |
| Journal |
Circulation |
| Volume |
|
| Year |
1998 |
| Abstract |
No Abstract Available. |
| Title |
Enhancement of sonochemical reactions by second-harmonic superimposition. |
| Author |
Umemura S, Kawabata K. |
| Journal |
Proc Ultrason Symp IEEE |
| Volume |
|
| Year |
1993 |
| Abstract |
Effect of second-harmonic superimposition on cavitation and sonochemical reaction was investigated in a propagation mode by using a plane wave transducer piezoelectrically active at both fundamental and second-harmonic frequencies. The rate of iodine release induced by ultrasound at 1 MHz with a superimposed wave at 2 MHz showed significant dependence on the phase relation between the two waves. The largest rate was obtained at the relative phase which maximizes the magnitude of negative peak pressure while almost no iodine release was observed at the relative phase which maximizes the magnitude of positive peak pressure. At this optimum relative phase, the dependence of iodine release and subharmonic emission on the ultrasound power at 1 MHz and 2 MHz was studied. The results clearly show the synergistic effects of the fundamental and second harmonic on the chemical reaction and on higher-order subharmonic emission which typically accompanies acoustic cavitation. |
| Title |
Enhancement of sonodynamic tissue damage production by second-harmonic superimposition: Theoretical analysis of its mechanism. |
| Author |
Umemura S, Kawabata K, Sasaki K. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
1996 |
| Abstract |
Abstract--Among the nonthermal effects of ultrasound, acoustic cavitation may have the highest potential for therapeutic applications if it can be somehow controlled. Recent in vitro and in vivo experiments have demonstrated that sonochemically active cavitation can be enhanced an order of magnitude by superimposing the second harmonic onto the fundamental in insonation. Moreover, they have shown that sonochemically active cavitation can be controlled with relative ease, thereby even in a progressive wave field. The effect of second-harmonic superimposition on the rectified diffusion through the gas-liquid interface of cavitated microbubbles is estimated theoretically. The theoretical rectified diffusion rate explained an asymmetric behavior of the threshold for producing sonodynamic tissue damage as a function of the fundamental and the second-harmonic amplitudes. The tissue damage was produced with a focused progressive wave in a liver lobe of a mouse administered with a sonodynamically active agent. The result suggests that the acceleration of the rectified diffusion is a primary mechanism of the enhancement of sonodynamically effective cavitation by second-harmonic superimposition. |
| Title |
Enhancement of thrombolysis by ultrasound. |
| Author |
Olsson SB, Johansson B, Nilsson AM, Olsson C, Roijer A. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1994 |
| Abstract |
Drug-induced early reperfusion in acute myocardial infarction reduces myocardial damage and decreases mortality. A further beneficial effect may be achieved if the time from start of thrombolytic treatment to reperfusion, on average 45 min, can be shortened. With this purpose in mind, we have analysed the effect of ultrasound on the reperfusion time in an experimental model in vitro. A cylindrical fibrin thrombus with a 2 mm diameter and a 20 microL volume was made by thrombin activation of a pure 0.5% fibrinogen solution in a soft silicone tube. The tube was placed in a low pressure perfusion system and maintained at 37 degrees C. The thrombi were then exposed to hydrostatic loading with a streptokinase concentration of 5000 units/mL. Reperfusion times (RT) were measured from time of Streptokinase exposure to fluid passage, identified by the photoelectric technique. RT increased significantly with increasing thrombus age (r = 0.92, p < 0.05) and was 34-45 min (95% confidence limits) at a thrombus age of 1 h and 102-122 min at a thrombus age of 2 h. RT was unaffected by temperatures between 33 and 45 degrees C but increased with higher temperatures. All investigations of ultrasound effects were performed with 1 h old thrombi and at 37 degrees C. RT decreased by 49% (p < 0.01) as an effect of exposure to 1 MHz ultrasound at 1 W/cm2 SATA. Intermittent ultrasound exposure for 10 microseconds/ms with the same intensity and frequency shortened RT by 54% (p < 0.01). 1 MHz ultrasound at 5 W/cm2 prevented the thrombolysis completely, whilst intermittent exposure, 10 microseconds/ms of 1 MHz at 5 W/cm2, did not significantly effect RT. RT was shortened by 65% as an effect of exposure to ultrasound of 170 kHz reduced RT by 48%. We conclude that ultrasound exposure of a type and intensity that may be transmitted transthoracically accelerates the thrombolytic process under experimental conditions. The potential benefit of this technique clearly motivates further studies. |
| Title |
Enhancement of ultrasonically induced cell damage by.a gallium-porphyrin complex, ATX-70. |
| Author |
Umemura S, Yumita N, Nishigaki R..Advanced Research Laboratory, Hitachi, Ltd., Saitama. |
| Journal |
Jpn J Cancer Res |
| Volume |
|
| Year |
1993 |
| Abstract |
Enhancement of ultrasonically induced cell damage by a gallium-porphyrin complex [ATX-70,.2,4-bis(1-decyloxyethyl)-Ga(III)-1,3,5,8- tetramethylporphryin-6,7-dipropionyl diaspartic acid] was investigated. The rate of damage to isolated sarcoma 180 cells in air-saturated suspension induced by 2 MHz ultrasound irradiation was enhanced more than four times by 80 microM ATX-70 in contrast to only twice by the same concentration of hematoporphyrin (Hp). The enhancement was almost completely inhibited in the presence of 10 mM histidine in the suspension, but not at all by 100 mM mannitol, which suggests that the enhanced cell damage was mostly mediated by singlet oxygen. Ultrasonically induced active oxygen generation in an air-saturated aqueous solution of ATX-70 was studied by detecting the electron spin resonance signals of 2,2,6,6,-tetramethyl-4-piperidone-N-oxyl produced by the reaction of 2,2,6,6-tetramethyl-4-piperidone with the generated active oxygen species. The rate of ultrasonically induced nitroxide generation was enhanced five times by 80 microM ATX-70 in contrast to only twice by Hp. The enhancement was inhibited significantly in the presence of 10mM histidine in the suspension, but not at all by 100 mM mannitol. The singlet oxygen generation in air-saturated aqueous solution was further confirmed by the bleaching of N,N-dimethyl-4-nitrosoaniline in the presence of imidazole. The ultrasonically induced bleaching rate was enhanced six times by ATX-70, in contrast to only twice by Hp. |
| Title |
Enhancement of ultrasonically-induced hemolysis by perfluorocarbon-based compared to air-based echo-contrast agents. |
| Author |
Miller DL, Gies RA. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1998 |
| Abstract |
Hemolysis induced by ultrasonic activation of various contrast-agent gas bodies was investigated. Canine whole blood, with high concentrations of the agents held in 1 mm thick chambers, was exposed in the nearfield of a 2.4-MHz ultrasound beam in a 37 degree C water bath. Sterile phosphate buffered saline (PBS) served as a control agent without gas bodies. Albunex (Mallinckrodt Medical, St. Louis, MO) and Levovist (Schering AG, Berlin, Germany) represented the air-based contrast agents. The experimental agents FS069(Optison, Molecular Biosystems Inc., San Diego, CA) and modified MRX-130 (ImaRx Pharmaceutical Corp., Tucson, AZ)represented perfluorocarbon-based contrast agents. No significant ultrasonically-induced hemolysis was detected for the PBS or Levovist suspensions. After 1 s continuous exposure, ultrasonically-induced hemolysis was significant for Albunex at 0.4 MPa or higher pressure amplitudes, for FS069 at 0.2 MPa and for modified MRX-130 at 0.4 MPa. Hemolysis found after pulsed exposure with 10 micros pulses and 1 ms pulse repetition period was significant for Albunex, FS069 and modified MRX-130 above thresholds of 1.1 MPa, 0.57 MPa and 1.6 MPa, respectively. FS069 led to more hemolysis after pulsed mode exposures of 1 s duration or longer than did Albunex. Reduced concentrations of gas bodies gave increased thresholds and reduced hemolysis. These results indicate that improvements in persistence of contrast agents, which increase their clinical utility, may also enhance the potential for cavitational bioeffects. |
| Title |
Enhancement of ultrasound‐mediated transfection with cavitation micronuclei. |
| Author |
Greenleaf JF, Greenleaf WJ, Kinnick R, Sarkar G, Bolander MA. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1998 |
| Abstract |
Many methods are available for transferring foreign genes into mammalian cells (transfection). The advantages of ultrasound‐mediated transfection are that it can be controlled in both space, by focusing, and time, by exposure. It was tested whether ultrasound‐mediated gene transfection in cultured immortalized human chondrocytes would be enhanced using artificial cavitation nuclei in the form of Albunex®. Here 1.0 MHz ultrasound transmitted through the bottoms of six‐well culture plates containing media with green fluorescent protein reporter gene plasmids at a concentration of 40 μg/ml and Albunex® at 50×106 bubbles/ml produced a peak transfection efficiency of about 50% of the living cells when exposure was 4×105 P spatial average peak pressure (SAPP) for 20 mins. Using these parameters, transfection efficiency increased linearly with ultrasound exposure pressure with a transfection threshold observed at a SAPP of 105 P. Adding fresh Albunex® at 50×106 bubbles/ml prior to sequential one second 3.2 or 4.0×105 P exposures increased transfection efficiency by 15% for each of three consecutive exposures. Efficient in vitro and perhaps in vivo transfection appears possible with ultrasound providing both temporal and spatial control over the transfection process. |
| Title |
Enhancing cell kill in vitro from hyperthermia through pre-sensitizing with ultrasound-stimulated microbubbles |
| Author |
Ghoshal G, Oelze ML |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
2015 |
| Abstract |
Ultrasound-stimulated microbubbles (MBs) were demonstrated to enhance cell kill from hyperthermia. Definity MBs were injected into wells containing 4T1 cells in culture media and scanned with 1-MHz ultrasound, an exposure duration of 30 s and a negative pressure of 0.5 or 1.3 MPa. Some cell samples were placed in a water bath heated to 42 C for 5 min. Cell death was quantified. When combining MBs, ultrasound at 1.3 MPa and hyperthermia, more than 58.8% 7.21% of cells were nonviable. When exposed to hyperthermia alone or exposure to MBs and ultrasound but no hyperthermia, cell death was less than 10.1% 6.96% and 30.1% 10.8%, respectively. |
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