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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 322 out of 330
| Title |
Ultrasound-mediated gene transfection: Problems to be solved and future possibilities. |
| Author |
Nozaki T, Ogawa R, Watanabe A, Nishio R, Fuse H, Kondo T. |
| Journal |
J Med Ultrasonics |
| Volume |
|
| Year |
2006 |
| Abstract |
Together, the human genome project and advances in molecular biology have led to identification of many genes, some useful in the field of medicine. Gene therapy has opened a potentially new therapeutic avenue for managing an array of complicated diseases. One of the more critical areas of gene therapy is the design of an appropriate, accurate, and effective gene transfer system that can be safely applied in vivo. Because no known system meets all the requirements for clinical use, a better, more versatile method of gene transfer is desired. Ultrasound-mediated transfection (USMT) could serve as a potential site-specific gene transfer modality. Although no actual mechanism has yet been thoroughly described, we focus on the principles of USMT, discuss the use of microbubbles as a gene-transfer mechanism, and summarize preliminary in vivo experiments using microbubbles as vectors. Although the published data suggest the promise of this method, extensive improvement in USMT remains essential. Reassuringly, recent success in USMT research has positioned ultrasound as a highly safe modality for gene transfer. |
| Title |
Ultrasound-mediated microbubble destruction enhances the efficacy of bone marrow mesenchymal stem cell transplantation and cardiac function. |
| Author |
Song X, Zhu H, Jin L, Wang J, Yang Q, Jin P, Li X. |
| Journal |
Clin Exp Pharmacol Physiol |
| Volume |
|
| Year |
2008 |
| Abstract |
Application of ultrasound (US) to intravascular microbubble (MB) contrast agents causes small capillary ruptures. The purpose of the present study was to examine the effects of US-mediated MB destruction on bone marrow mesenchymal stem cell (BMSC) transplantation into the infarcted myocardium and to evaluate whether this approach could improve cardiac function. 2. Ultrasound was applied to the anterior chest of rabbits after intravenous injection of MB followed by infusion of BMSC. There were four groups investigated: (i) a control group, in which neither US nor MB were used prior to infusion of BMSC; (ii) one group subjected to US alone prior to infusion of BMSC; (iii) another group injected with MB prior to infusion of BMSC; and (iv) a group in which US was applied to MB prior to the infusion of BMSC. Cardiac function was evaluated by echocardiography 24 h and 4 weeks after cell transplantation. All rabbits were killed to enable histological and immunochemical examination. 3. Echocardiography 24 h after infusion of BMSC indicated no difference in cardiac function between any of the groups, as assessed by left ventricular ejection fraction (LVEF), left ventricular end-diastolic dimensions (LVDD), left ventricular systolic diameter (LVSD) and fractional shortening (FS%; all P > 0.05). However, 4 weeks after BMSC transplantation, there was a significant improvement in LVEF in the group subjected to US plus MB compared with the control, US alone and MB alone groups (59.5 +/- 3.5, 52.5 +/- 5.5, 52.8 +/- 5.2 and 51.1 +/- 3.5%, respectively; all P < 0.05). In addition, treatment with US plus MB significantly reduced LVDD and LVSD and increased capillary density in the infarcted area. 4. In conslusion, the results of the present study indicate that using US-mediated MB destruction prior to BMSC transplantation into the infarcted myocardium improves the effectiveness of cardiac cell therapy and cardiac function in rabbits. |
| Title |
Ultrasound-mediated transdermal protein delivery. |
| Author |
Mitragotri S, Blankschtein D, Langer R. |
| Journal |
Science |
| Volume |
|
| Year |
1995 |
| Abstract |
Transdermal drug delivery offers a potential method of drug administration. However, its application has been limited to a few low molecular weight compounds because of the extremely low permeability of human skin. Low-frequency ultrasound was shown to increase the permeability of human skin to many drugs, including high molecular weight proteins, by several orders of magnitude, thus making transdermal administration of these molecules potentially feasible. It was possible to deliver and control therapeutic doses of proteins such as insulin, interferon gamma, and erythropoeitin across human skin. Low frequency ultrasound is thus a potential noninvasive substitute for traditional methods of drug delivery, such as injections. |
| Title |
Ultrasound-mediated transdermal transport of insulin in vitro through human skin using novel transducer designs. |
| Author |
Smith NB, Lee S, Maione E, Roy RB, McElligott S, Shung KK. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2003 |
| Abstract |
Recent studies have shown that ultrasound (US)-mediated transdermal drug delivery offers a promising potential for noninvasive drug administration. The purpose of this study was to improve low-frequency (20 kHz) US methods for enhancing the transport of insulin in vitro across human skin. The feasibility of using US produced by small, lightweight novel transducers was explored for enhancing the transport of insulin across skin. Previous investigators have used US devices such as large, heavy sonicators or commercially obtained transducers for this type of research. The experiments carried out in this study used two low-profile novel US transducer arrays, the stack and standard array, for improved transport of insulin. The stack array generated a spatial peak temporal peak intensity (ISPTP) of 15.4 ± 0.6 mW/cm2 and the standard array had an ISPTP of 173.7 ± 1.2 mW/cm2. Spectrophotometeric absorption techniques were used for determining insulin transport in vitro across human skin. Compared with passive transmission (4.1 ± 0.5 U) over an exposure period of 1 h, the standard array facilitated over a sevenfold increase in the noninvasive transdermal transport of Humulin® R insulin (45.9 ± 12.9 U). Using Humalog® insulin with the standard array, there was a fourfold increase in the US-facilitated transmission over that in the control. These promising results indicate that low-frequency US can be used in a practical device for enhanced transport across the stratum corneum.
|
| Title |
Ultrasound-mediated transfection of mammalian cells. |
| Author |
Kim HJ, Greenleaf JF, Kinnick RR, Bronk JT, Bolander ME. |
| Journal |
Hum Gene Ther |
| Volume |
|
| Year |
1996 |
| Abstract |
Mammalian cells were successfully transfected with plasmid DNA in vitro using ultrasound transmitted through the walls of cell culture flasks or plates. Primary rat fibroblasts or chondrocytes were exposed to ultrasound in the presence of plasmids containing lacZ or neo genes. The transfection efficiency was evaluated by counting the number of beta-galactosidase (beta-Gal) positive cells or neomycin-resistant colonies. Transfection efficiency was optimized by varying ultrasound conditions, ambient temperatures (room temperature or 37 degrees C), plasmid concentrations, and initial cell populations. Additional experiments were performed performed to.elucidate the mechanism of the ultrasound-mediated transfection. Maximal gene transfection was seen with two ultrasound conditions: 1-MHz carrier frequency 411 +/- 189 kPascal continuous wave with20 or 30 sec of exposure time, and 1 MHz carrier frequency 319 +/- 157 kPascal continuous wave with 40 or 60 sec of exposure time. Gene expression was negligible when transfection procedures were.performed at room temperature. The average stable transfection rate was 0.34% of surviving cells with a plasmid concentration of 40 micrograms/ml in primary fibroblasts. The transient transfection rate was 2.4% of surviving cells for primary chondrocytes. Data suggest that increasing plasmid concentration will increase efficiency. Identical treatment with 3.5 MHz produced no transfection, implying.that cavitation produced by the ultrasound pressure wave appeared to play a critical role in mediating transfection. Ultrasound-mediated transfection was effective for suspended cells as well as for plated cells. This transfection method is simple, easy to keep sterile, and convenient. Ultrasound-mediated transfection appears to be a.promising method for gene transfer into mammalian cells. .. |
| Title |
Ultrasound-microbubble-induced neovascularization in mouse skeletal muscle. |
| Author |
Chappell JC, Klibanov, Price RJ. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2005 |
| Abstract |
Ultrasound-microbubble (US-MB) interactions stimulate neovascularization in rat gracilis muscle (GM). We examined microvascular remodeling (MVR) in GMs of C57BL/6 and balb/C mice following ultrasonic MB destruction. A range of MB dosages were administered IV, and exposed GMs received US. Muscles harvested 3, 7 and 14 d posttreatment were stained for vascular markers and assessed for changes in microvessel number, diameter and length. Muscles receiving a low MB dose (LMBD) and US showed significant increases in microvascular density after 3 d, returning to sham levels after one week. A MB dose producing maximum capillary disruptions was then established. This high MB dose (HMBD) facilitated significant MVR in C57BL/6 mice after one week. Balb/C GMs exhibited neovascularization 3 d, but not 7 or 14 d, following US-HMBD treatment. We conclude that HMBD in C57BL/6 mice induces a more sustained neovascularization response compared to balb/C or LMBD-treated C57BL/6 muscles; however, this response is still impermanent. |
| Title |
Ultrasound-stimulated vibro-acoustic spectrography. |
| Author |
Fatemi M, Greenleaf JF |
| Journal |
Science |
| Volume |
|
| Year |
1998 |
| Abstract |
An ultrasound method based on radiation force is presented for imaging the acoustic response of a material to mechanical excitation. Acoustic energy was emitted from solids and tissues in response to an oscillatory radiation force produced by interfering focused beams of ultrasound. Frequency spectra of ultrasound-stimulated acoustic emission exhibited object resonances. Raster-scanning the radiation force over the object and recording the amplitude and phase of the emitted sound resulted in data from which images related to the elastic compositions of the acoustically emitting objects could be computed. Acoustic emission signals distinguished tuning-fork resonances, submillimeter glass spheres, and calcification in excised arteries and detected object motions on the order of nanometers. |
| Title |
Ultrasound. |
| Author |
Hill CR, Haar GT( Suess MJ eds). |
| Journal |
Book Chapter |
| Volume |
|
| Year |
1982 |
| Abstract |
Ultrasound is a form of mechanical energy that has found increasingly widespread application over the past fifty years.Many of its uses entail exposure of human beings,either incidentally or,as in the case of medical applications of ultrasound,as an essential part of the procedure. The fact of such exposures inevitably raises the question of the possible existence of any corresponding hazard to the individual exposed.
This is a question that has been the subject of investigation over a long period of time(49), but to which there is still no thoroughly satisfactory answer.
The physical nature of ultrasound, the physical laws that determine its behaviour, and the principal methods that are available for measuring the characteristics of ultrasound fields are important aspects to be looked at. The main practical applications of ultrasound are considered from the ponit of view of the possibilities that they entail for exposure of humans to ultrasound fields. The evidence that exists for induction of biological change is considered,with emphasis on quantitative relationships between induced changes of a potentially damaging nature and the physical natures by which these changes may be induced. The tentative conclusions reached cncern the levels of exposure that may need to be considered as constituting limits of safe operation.
In choosing the reference to be included in this chapter, those results that have been available for critical comment in referred journals have been preferred. However, some reports are necessarily more recent, or less easily available.
|
| Title |
Ultrasound. |
| Author |
Dunn F. |
| Journal |
IEEE Trans Educ |
| Volume |
|
| Year |
1991 |
| Abstract |
A brief accounting is given of the concerns for possible biological effects from diagnostic ultrasound, though none have been reported. A delineation of the activities of the NCRP Committee 66, regarding recommendations, is included. The AIUM STATEMENT remains useful for communicating basic ultrasound bioeffects information to a diverse medical community. |
| Title |
Ultrasound: A completely safe method? |
| Author |
Huerta LK, |
| Journal |
Appl Radiol Ultrasound |
| Volume |
|
| Year |
1977 |
| Abstract |
No abstract available. |
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