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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 166 out of 330
| Title |
Low-intensity pulsed ultrasound produced an increase of osteogenic genes expression during the process of bone healing in rats. |
| Author |
Fávaro-Pípi E, Bossini P, de Oliveira P, Ribeiro JU, Tim C, Parizotto NA, Alves JM, Ribeiro DA, Selistre de Araújo HS, Renno AC. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2010 |
| Abstract |
The aim of this study was to measure the temporal expression of osteogenic genes during the process of bone healing in low-intensity pulsed ultrasound (LIPUS) treated bone defects by means of histopathologic and real-time polymerase chain reaction (PCR) analysis. Animals were randomly distributed into two groups (n = 30): control group (bone defect without treatment) and LIPUS treated (bone defect treated with LIPUS). On days 7, 13 and 25 postinjury, 10 rats per group were sacrificed. Rats were treated with a 30 mW/cm(2) LIPUS. The results pointed out intense new bone formation surrounded by highly vascularized connective tissue presenting a slight osteogenic activity, with primary bone deposition was observed in the group exposed to LIPUS in the intermediary (13 days) and late stages of repair (25 days) in the treated animals. In addition, quantitative real-time polymerase chain reaction (RT-qPCR) showed an upregulation of bone morphogenetic protein 4 (BMP4), osteocalcin and Runx2 genes 7 days after the surgery. In the intermediary period, there was no increase in the expression. The expression of alkaline phosphatase, BMP4 and Runx2 was significantly increased at the last period. Our results indicate that LIPUS therapy improves bone repair in rats and upregulated osteogenic genes, mainly at the late stages of recovery. |
| Title |
Low-intensity ultrasound induces angiogenesis in rat hind-limb ischemia. |
| Author |
Barzelai S Sharabani-Yosef O Holbova R Castel D Walden R Engelberg S Scheinowitz M. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2006 |
| Abstract |
We investigated the effect of low-intensity ultrasound (US) on tissue blood flow and angiogenesis after limb ischemia in vivo. Rats underwent surgical ligation of the femoral or the iliac arteries. Half the animals were exposed to low-intensity US (0.05 W/cm2) during three consecutive sessions. At 3 weeks postsurgery, limb perfusion was assessed using laser Doppler and angiography. Immunostaining and vascular endothelial growth factor (VEGF) messenger ribonucleic acid (mRNA) expression were performed 7 d postsurgery. US irradiation significantly improved limb perfusion in both ischemic models (p = 0.04). Angiography showed increased blood vessels in the moderate ischemia (p = 0.01), but not in the severe ischemia (p = 0.19). Histology demonstrated a significantly higher number of blood vessels and proliferating cells in US-irradiated moderate and severe ischemia (p = 0.002 and p = 0.03, respectively). VEGF mRNA was significantly higher in moderate ischemia (p = 0.02). No differences in apoptotic cell death were evident in the models. Low-intensity US significantly improved tissue blood flow and angiogenesis, irrespective of the extent of the ischemia. |
| Title |
Low-intensity ultrasound-exposed microbubbles provoke local hyperpolarization of the cell membrane via activation of BKCa channels. |
| Author |
Juffermans LJM, Kamp O, Dijkmans PA, Visser CA, Musters RJP. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2008 |
| Abstract |
Ultrasound (US) contrast agents have gained wide interest in gene therapy as many researchers reported increased membrane permeability and transfection efficiency by sonoporation in the presence of US contrast agents. We recently demonstrated an increase in cell membrane permeability for Ca2+ in rat cardiomyoblast (H9c2) cells insonified in the presence of microbubbles. In the present study, we specifically investigated whether US-exposed microbubbles have an effect on the cell membrane potential and whether Ca2+-dependent potassium (BKCa) channels are involved. We particularly focused on local events where the microbubble was in contact with the cell membrane. H9c2 cells were cultured on US transparent membranes. US exposure consisted of bursts with a frequency of 1 MHz with a peak-to-peak pressure of 0.1 or 0.5 MPa. Pulse repetition frequency was set to 20 Hz, with a duty cycle of 0.2%. Cells were insonified during 30 s in the presence of Sonovue™ microbubbles. The membrane potential was monitored during US exposure using the fluorescent dye di-4-aminonaphtylethenylpyridinium (di-4-ANEPPS). The experiments were repeated in the presence of iberiotoxin (100 nM), a specific inhibitor of BKCa channels. Surprisingly, despite the previously reported Ca2+ influx, we found patches of hyperpolarization of the cell membrane, as reflected by local increases in di-4-ANEPPS mean intensity of fluorescence (MIF) to 118.6 ± 2.5% (p < 0.001, n = 267) at 0.1 MPa and 125.7 ± 5.9% (p < 0.001, n = 161) at 0.5 MPa at t = 74 s, respectively, compared with “no US” (100.3 ± 3.4%, n = 52). This hyperpolarization was caused by the activation of BKCa channels, as iberiotoxin completely prevented hyperpolarization. (MIFt74 = 100.6 ± 1.4%; p < 0.001, n = 267) and 0.5 MPa (MIFt74 = 88.8 ± 2.0%; p< 0.001, n = 193), compared with 0.1 and 0.5 MPa microbubbles without iberiotoxin. In conclusion, US-exposed microbubbles elicit a Ca2+ influx, which leads to activation of BKCa channels and a subsequent, local hyperpolarization of the cell membrane. This local hyperpolarization of the cell membrane may facilitate uptake of macromolecules through endocytosis and macropinocytosis. |
| Title |
Low-kilohertz-water-borne ultrasound biological effects. |
| Author |
Carnes KI, Dunn F. |
| Journal |
Radiat Environ Biophys |
| Volume |
|
| Year |
1986 |
| Abstract |
The effects of 25 kHz ultrasound on murine testes was studied, as mimicking possible World WAR II SONAR exposure to swimming maintenance personnel. Very few specimens were found to exhibit morphological tissue alterations, depending upon length of exposure time and proximity of the source to the tissue. Thermal processes seem to be eliminated, but microstreaming may be implicated, as the physical mechanism(s) of interaction. |
| Title |
Low-reflection-coefficient liquid interfaces for system characterization. |
| Author |
Hall TJ, Madsen EL, Dong F, Medina IR, Frank GR. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2001 |
| Abstract |
The use of liquid brominated hydrocarbons to form a planar reflecting interface with water is described. Gravity-based planar reflecting surfaces with known reflection coefficients can be used in system characterization for quantitative ultrasonics, and a set of surfaces with a range of reflection coefficients allows calibration of the output power and receiver gain of ultrasonic imaging systems. The substances reported here are immiscible in water and form interfaces with water, resulting in a broad range of acoustic reflection coefficients. Reflection coefficients were measured at temperatures from 18-24 degrees C for "pure" substances and for mixtures of two brominated hydrocarbons. Results show that reflection coefficients are weakly dependent on temperature and that, at a specific temperature, a significant range of arbitrarily small reflection coefficients is available, in the case of the mixtures, by the appropriate choice of weight-percents of the two brominated hydrocarbons. |
| Title |
Lung damage assessment from exposure to pulsed-wave ultrasound in the rabbit, mouse, and pig. |
| Author |
O'Brien WD Jr, Zachary JF. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
1997 |
| Abstract |
The principal motivation of the study was to assess experimentally the question: "Is the MI (Mechanical Index) and equivalent or better indicator of nonthermal bioeffect risk than I(SPPA.3) (derated spatial peak, pulse average intensity)?". To evaluate this question, the experimental design consisted of a reproducible biological effect in order to provide a quantitative assessment of the effect. The specific biological effect used was lung damage and the species chosen was the rabbit. This work was initiated, in part, by a study [1] in which lung hemorrhage was observed in 7-week old C3H mice for diagnostic-type, pulsed wave ultrasound exposures, and therefore, 6- to 7-week old C3H mice were used in this study as positive controls. Forty-seven adult New Zealand White male rabbits were exposed to a wide range of ultrasound amplitude conditions at center frequencies of 3 and 6 MHz with all temporal exposure variables held constant. A calibrated, commercial diagnostic ultrasound system was used as the ultrasound source with output levels exceeding, in some cases, permissible FDA levels. The MI was shown to be at least an equivalent, and in some cases, a better indicator of rabbit lung damage than either the I(SPPA.3) or Pr.3 (derated peak rarefactional pressure), thus answering the posed question positively. Further, in situ exposure conditions were estimated at the lung pleural surface (PS); the estimated in situ I(SPPA.PS) and Pr.PS exposure conditions tracked lung damage no better than I(SPPA.3) and Pr.3, respectively, whereas the estimated in situ MI(PS) exposure condition was a slightly poorer predictor of lung damage than MI. Finally, the lungs of six adult cross-bred pigs were exposed at the highest amplitude exposure levels permitted by the diagnostic ultrasound system (to prevent probe damage) at both frequencies; no lung damage was observed which suggests the possibility of a species dependency biological effect. |
| Title |
Lung damage from exposure to pulsed ultrasound. |
| Author |
Child SZ, Hartman CL, Schery LA, Carstensen EL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1990 |
| Abstract |
Motivated by a recent finding that threshold pressures for hemorrhage in.mouse lung exposed to the fields of an electrohydraulic lithotripter were less.than 2 MPa, we extended the exposures to pulsed ultrasound. Sharply defined.thresholds of the order of 1 MPa were found with 10 microseconds length.pulses and roughly twice that value for 1 microsecond pulses. The thresholds.at 4 MHz are greater than at 1 MHz. The thresholds are comparable for.focused and unfocused fields. As would be expected for a cavitation-like.phenomenon, temporal average intensity is a very poor predictor of this effect..In the extreme case, lesions were found at temporal average intensities on the.order of 1 mW/cm(^2). . |
| Title |
Lung damage from exposure to the fields of an electrohydraulic lithotripter. |
| Author |
Hartman C, Child SZ, Mayer R, Schenk E, Carstensen EL. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1990 |
| Abstract |
Threshold pressures for hemorrhage in mouse lung exposed to the fields of an.electrohydraulic lithotripter appear to be less than 2 MPa with as few as 10 pulses.and with severe damage occurring at levels between 5 and 6 MPa. This is very.much smaller than the fields required to fragment kidney and gallstones and.smaller than the thresholds for damage to kidney tissues. Fetal lung, in contrast,.did not show signs of damage at 20 MPa. The lower sensitivity of fetal lung is.consistent with a cavitation-related mechanism for lung damage by shock waves..Since the pressures in these exposures are almost entirely positive, it suggests.that the value of negative pressures as predictors of the behavior of gas bodies in.tissues should be reconsidered. |
| Title |
Lung hemorrhage caused by diagnostic ultrasound..Review of the literature.[Article in German] |
| Author |
Rott HD..Institut fur Humangenetik, Universitat Erlangen-Nurnberg. |
| Journal |
Ultraschall Med |
| Volume |
|
| Year |
1997 |
| Abstract |
In animals pulsed diagnostic ultrasound is capable of causing subpleural capillary lung bleeding if the pressure amplitude is above 1 MPa. Precondition is pulmonary ventilation; fetal organs are, therefore, not at risk. Capillary lung bleeding is a threshold effect depending on pressure amplitude and frequency. The degree of injury is apparently also influenced by the alveolar size. The same effect can be observed in the intestine at pressure amplitudes above 2 MPa. It is not known whether the effect is also caused by sonographic examination in humans. Should this be the case, the lesions would be of minor relevance and probably without any clinical symptoms. Nevertheless, during examination it would be advisable to restrict the ultrasound exposure of lung and intestine to the minimum necessary for reliable diagnosis. ..Publication Types:.. Review . Review, tutorial. |
| Title |
Lung lesions induced by continuous- and pulsed-wave (diagnostic) ultrasound in mice, rabbits, and pigs. |
| Author |
Zachary JF, O'Brien WD Jr. |
| Journal |
Vet Pathol |
| Volume |
|
| Year |
1995 |
| Abstract |
These studies documented the presence or absence of macroscopic and microscopic intraparenchymal hemorrhage in individual lung lobes of mice, rabbits, and pigs exposed to continuous- and pulsed-wave (diagnostic) ultrasound; we described the character of and lesions associated with the hemorrhage and compared differences in the lesions among species and exposure conditions to investigate the pathogenic mechanisms and species differences associated with ultrasound-induced lung hemorrhage. In a series of three sequential interdependent studies, 312 mice, 91 rabbits, and 74 pigs were divided at random into experimental groups and exposed to continuous-wave ultrasound (3 kHz modulated at 120 Hz) of acoustic pressure levels ranging from 0 to 490 kPa for 5, 10, or 20 minutes. In a fourth study, three mice, 43 rabbits, and six pigs were divided at random into experimental groups and exposed to pulsed-wave ultrasound (3- and 6-MHz center frequency) of peak rarefactional.acoustic pressure levels ranging from 0 to 5.6 MPa for 5 minutes. Macroscopic lesions induced by continuous- and pulsed-wave ultrasound consisted of dark red to black areas of hemorrhage that extended from visceral pleural surfaces into lung parenchyma. Hemorrhage appeared spatially related to the edges of lung lobes where pleura of dorsal and ventral surfaces met, occurred in specific lung lobes in all three species, and appeared anatomically related to lung that was closest to and in contiguous alignment with the ultrasound transducer and thus the path of the sound beam. Macroscopic lesions were similar in all species under all exposure conditions for both continuous- and pulsed-wave ultrasound; however, hemorrhage was not induced in pig lung exposed to pulsed-wave ultrasound at.any peak rarefactional acoustic pressure level. Eighteen mice (145 kPa exposure.pressure), 60 rabbits (145-460 kPa exposure pressure), and 58 pigs (145-490 kPa exposure pressure) from study 3 were used for microscopic evaluation of.lung exposed to continuous-wave ultrasound; three mice (6 MHz; 2.9 and 5.4 MPa), 39 rabbits (3 and 6 MHz; 2.3-5.4 MPa), and six pigs (3 and 6 MHz; 3.3, 5.4, and 5.6 MPa) from study 4 were used for microscopic evaluation of lung exposed to pulsed-wave ultrasound. Microscopic lesions and the character of hemorrhage induced by continuous-wave ultrasound were different from those induced by pulsed-wave ultrasound. Lesions induced by continuous-wave ultrasound under all exposure conditions were similar in all three species. Lesions induced by pulsed-wave ultrasound under all exposure conditions were similar in all three species. |
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