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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 97 out of 330
| Title |
Effect of a stabilized microbubble echo contrast agent on hemolysis of human erythrocytes exposed to high intensity pulsed ultrasound. |
| Author |
Brayman AA, Azadniv M, Makin IRS, Miller MW, Carstensen EL, Child SZ, Raeman CH, Meltzer RS, Everbach EC. |
| Journal |
Echocardiography |
| Volume |
|
| Year |
1995 |
| Abstract |
Microbubble contrast agents have been shown to enhance ultrasonic cell lysis in vitro when exposed to continuous-wave ultrasound having spatial peak temporal average (SPTA) intensities of a few W/cm(2). The response is strongly dependent upon the hematocrit (HCT) of the cell sample; detectable cell lysis essentially disappears as the HCT approaches 5%-10%. This study was conducted to determine whether high intensity pulsed ultrasound is an effective lytic agent in the presence of preexisting potential cavitation nuclei (Albunex? contrast agent). Human erythrocytes were suspended in autologous plasma to HCTs ranging from 1%-40%. Suspensions were exposed or sham exposed for 60 seconds to focused, pulsed ultrasound. The pulse duration was 1 msec, and the pulse repetition frequency was 20 Hz. The pressure amplitudes, spatial peak pulse average (SPPA) intensity, and SPTA intensity were 4.7 Mpa peak positive pressure, -2.7 Mpa peak negative pressure, 420 W/cm(2), and 8.5 W/cm(2), respectively. Samples were exposed to ultrasound in a dialysis membrane exposure vessel rotating at 200 rpm. When included in the erythrocyte samples, the Albunex concentration was 35 uL/mL suspension. Significant ultrasound-induced hemolysis in the absence of Albunex was observed only at the lowest HCT value tested (1%). In the presence of Albunex significant cell lysis was observed at all tested HCT values. The relative fraction of cells lysed by the combination of ultrasound exposure and Albunex diminished with increasing HCT, but the number of cells lysed per sample was nearly constant over the range of 5%-40% HCT. The ultrasound exposure parameters used in this study differ substantially from those associated with diagnostic imaging equipment; it is not valid to infer from the present results that the use of Albunex in diagnostic applications will induce or enhance hemolysis in vivo. |
| Title |
Effect of acoustic streaming on ultrasonic heating. |
| Author |
Wu J, Winkler AJ, O'Neill TP. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1994 |
| Abstract |
It was found in in vitro experiments performed on tissue phantoms that acoustic streaming in low attenuating fluid may dramatically reduce the temperature rise generated by ultrasound at the surface of bone, if the ultrasound path contains a low-attenuating-fluid/thin-soft-tissue/bone structure. The temperature rise at the surface of bone generated by a 3.5 MHz focused ultrasound beam of 180 mW source acoustic power and an average acoustic intensity at the focus of 5.8 W/cm2 was measured to be only 18% of the value predicted by an existing model, when the bone was in contact with the low attenuating fluid. When a bone surface that is covered by 1 mm thick soft tissue is exposed to the same ultrasound beam, the measured temperature rise at the tissue-bone surface is only 60% of the calculated value.
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| Title |
Effect of atropine on the biomechanical properties of the oesophageal wall in humans. |
| Author |
Takeda T, Kassab G, Liu J, Nabae T, Mittal RK. |
| Journal |
J Physiol |
| Volume |
|
| Year |
2003 |
| Abstract |
Recently, we reported a novel ultrasound technique to assess biomechanical properties of the oesophagus in human subjects. In the present study, we use the technique, in combination with atropine, to determine the active and passive biomechanical properties of the oesophagus in normal healthy humans. A manometric catheter equipped with a high-compliance bag and a high-frequency intraluminal ultrasonography probe was used to record pressure and oesophageal geometry. Oesophageal distensions with either isovolumic (5-20 ml water) or with isobaric (10-60 mmHg) technique were performed. Intra-bag pressure and ultrasound images of the oesophagus were recorded simultaneously. Following injection of atropine (15 microg kg-1, I.V.), the oesophageal distensions were repeated. The oesophageal wall compliance, circumferential wall tension, stress, strain and elastic modulus were calculated. Atropine resulted in an increase in the oesophageal wall compliance during isobaric distension, but no change in compliance was observed during isovolumic distension. The stress-strain relationship was found to be linear during both types of distension, before as well as after atropine. The Young's modulus, which is the slope of a linear stress-strain relationship, was significantly higher after atropine in the isovolumic study but not in the isobaric study. The stress-strain relationship of the active component (muscle contraction) was different during isovolumic and isobaric distensions but the passive components were similar. The passive and active stress-strain relationships of the human oesophagus resemble those of other soft biological tissues. Furthermore, the method of oesophageal distension has significant influence on the active but not the passive biomechanical properties due to a strain-rate effect. |
| Title |
Effect of continuous-wave ultrasound on blood flow in skeletal muscle. |
| Author |
Robinson SE, Buono MJ. |
| Journal |
Phys Ther |
| Volume |
|
| Year |
1995 |
| Abstract |
BACKGROUND AND PURPOSE. The purpose of this study was to determine.the effect of ultrasound on forearm, skin, and muscle blood flow. SUBJECTS..Twenty volunteers without known vascular problems (10 male, 10 female).participated. METHODS. All subjects received a treatment of continuous-wave.ultrasound to the anterior forearm at a dosage of 1.5 W/cm2 for a duration of 5.minutes. The contralateral forearm served as the control and received identical.treatment, except the ultrasound output remained at zero. Forearm blood flow.was measured using venous occlusion plethysmography, and skin blood flow.was measured using cutaneous laser-Doppler flowmetry before and after.ultrasound administration, with the difference being muscle blood flow..RESULTS. No differences between the control arm and the ultrasound-treated.arm were found for muscle, skin, and forearm blood flow. CONCLUSION.AND DISCUSSION. These results suggest that administration of.continuous-wave ultrasound at the prescribed dosage had no effect on skeletal.muscle blood flow for up to 30 minutes posttreatment. Thus, muscle hyperemia.is probably not the primary mechanism responsible for the clinical benefits seen.following the use of ultrasound as a therapeutic modality. .. |
| Title |
Effect of contrast agent on the incidence and magnitude of ultrasound-induced lung hemorrhage in rats. |
| Author |
O'Brien WD Jr, Simpson DG, Frizzell LA, Zachary JF. |
| Journal |
Echocardiography |
| Volume |
|
| Year |
2004 |
| Abstract |
OBJECTIVE: To test the hypothesis that inertial cavitation in the vasculature of the lung is not the physical mechanism responsible for ultrasound-induced lung hemorrhage. METHODS: A factorial design was used to study the effects of two types of injected agents (IA; 0.25 ml per rat of saline or Optison given intravenously) and two levels of pulsed ultrasound exposure (UE; in situ peak rarefactional pressures of 2.74 and 5.86 MPa; respective mechanical indices of 1.02 and 2.14) on the incidence and size of lung lesions. Ten 10-to-11-week-old Sprague-Dawley rats were exposed to pulsed ultrasound at each of the four combinations of IA and UE at a center frequency of 3.1 MHz, exposure duration of 10 s, pulse repetition frequency of 1,000 Hz and pulse duration of 1.2 micros. In addition, nine rats served as shams in which no lung hemorrhage occurred. RESULTS: Rats administered contrast agent prior to exposure did not have an increase in lesion occurrence or size compared to rats that received saline with no contrast agent. CONCLUSIONS: These results provide further evidence that the mechanism for production of lung hemorrhage is not inertial cavitation. |
| Title |
Effect of diagnostic and therapeutic intensities of ultrasonics on normal and malignant human cells in vitro. |
| Author |
Loch EG, Fischer AB, Kuwert E. |
| Journal |
Am J Obstet Gynecol |
| Volume |
|
| Year |
1971 |
| Abstract |
With the use of reduction of cell proliferation as an over-all parameter of cell damage, the effect of diagnostic (0.01 w. per square centimeter, 2.5 mHz.) and therapeutic (0.05 to 3 w. per square centimeter, 870 KHz.) intensities of ultrasound was studied in diploid and aneuploid human cells in tissue culture. With diagnostic ultrasound, no deleterious effect was observed in any of the 3 cell types tested. Therapeutic ultrasound, however, beginning with 0.1 w. per square centimeter, interfered with cell proliferation of all cell types studied and produced a growth reduction up to 60 per cent. |
| Title |
Effect of diagnostic ultrasound on maternal and fetal chromosomes. |
| Author |
Abdulla U, Campbell S, Dewhurst CJ, Talbert D, Lucas M, Mullarkey M. |
| Journal |
Lancet |
| Volume |
|
| Year |
1971 |
| Abstract |
The effect of diagnostic pulsed and continuous-wave ultrasound on maternal and fetal chromosomes was studied in patients for hysterotomy for termination of pregnancy. Of the 35 patients who were insonated, 12 were exposed to pulsed ultrasound, 12 to continuous wave ultrasound from a fetal-heart detector, and 11 to continuous wave ultrasound from a fetal-heart monitor. There was no increase in the number of chromosome aberrations in blood cultures from the mothers and fetuses who were insonated when compared with 11 mothers and fetuses who were not insonated. |
| Title |
Effect of drugs on mouse embryo hearts in organ culture visualized by acoustic microscopy. |
| Author |
Eggleton RC, Kessler LW, Vinson FS, Boder GB. |
| Journal |
Ultrasound Med |
| Volume |
|
| Year |
1976 |
| Abstract |
No abstract available. |
| Title |
Effect of fetal exposure to ultrasound on B cell development in BALB/c mice. |
| Author |
Desai BB, Sosolik RC, Ciaravino V, Teale JM. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1989 |
| Abstract |
Ultrasound is a major tool for clinical diagnosis, especially during prenatal life..Therefore, it is important that the potential bioeffects of ultrasound be determined..In this report, the effects of ultrasound on the development of B lymphocytes is.studied. Pregnant BALB/c mice were exposed to intensities of ultrasound ranging.from 0.1-3.0 W/cm2, receiving either a single exposure on day 11, or multiple.exposures on days 14, 15, and 18 or 19 of gestation. Fetal livers were removed.on day 19 of gestation whereas spleen cells were obtained from 5 and 10 day old.neonates. These cell populations were analyzed for: (a) the frequency of B220+ B.lineage cells; (b) the frequency of immunoglobulin-positive (Ig+) cells, and (c).the ability to proliferate in response to the B cell mitogen lipopolysaccharide.(LPS). None of the tests performed revealed any substantial differences between.ultrasound-exposed versus sham-treated control animals. In addition, the.development of blood cell types other than B lineage cells remained unaffected by.exposure to ultrasound. Therefore, exposure to ultrasound at the intensities used.does not appear to hinder hemopoiesis or the normal development of B.lymphocytes during fetal and early neonatal life. .. |
| Title |
Effect of fetal exposure to ultrasound on B lymphocyte function and antibody class production. |
| Author |
Sosolik RC, Desai BB, Ciaravino V, Teale JM. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1989 |
| Abstract |
The purpose of this study was to determine if ultrasound radiation would affect the ability of antigen-stimulated B cells and their clonal progeny to undergo the isotype switch and produce diverse antibody classes. Pregnant BALB/c mice were exposed to various intensities of ultrasound (0.1-3.0 W/cm2) at different ages of gestation. Spleens from the resulting offspring were removed five or ten days after birth. The splenocytes were analyzed for the frequency of B cells capable of responding to the hapten 2,4 dinitrophenyl (DNP) using the splenic fragment assay, a B cell cloning assay. The DNP-responsive B cell clones were then classified on the basis of isotype expression. It was found that ultrasonic radiation during gestation did not alter the frequency of B cells responding to DNP. Furthermore, ultrasound had no apparent effect on the B lymphocyte's capacity to switch to different isotypes after antigenic stimulation. Thus, the results indicate that prenatal exposure to ultrasound does not appreciably affect the genetic and cellular processes necessary for the isotype switch and antibody class production. |
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