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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 103 out of 330
| Title |
Effects of endothelin-1 on renal microvasculature measured using quantitative ultrasound. |
| Author |
Insana MF, Wood JG, Hall TJ, Cox GG, Harrison LA. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1995 |
| Abstract |
Renal vascular resistance is an important feature of kidney function and disease. To maintain adequate blood flow, renal vascular resistance varies in response to changes in systemic pressure. Vascular resistance is largely determined by arteriolar diameter, which is regulated by local and systemic factors. We used quantitative ultrasound techniques to follow renal vascular changes in anesthetized dogs during local intraarterial infusion of a potent vasoconstrictor, endothelin-1 (ET-1). Average arteriolar diameters were estimated by analyzing echo-signal spectra (1-15 MHz) obtained from renal cortex in vivo before, during, and after ET-1 infusion. At calculated arterial concentrations of 0.01 nM, 0.1 nM, and 1.0 nM, ET-1 reduced the average arteriolar diameter of 38 ? 2 ?m by 2%, 63%, and 91%, respectively, without producing a significant change in systemic blood pressure. Changes in scatterer size were consistent with the observed changes in renal hemodynamics detected using Doppler techniques. In addition, acoustic methods are sensitive to changes in renal arteriolar diameter, and may be new noninvasive method for continuously monitoring changes in vascular resistance. |
| Title |
Effects of energy-matched pulsed and continuous ultrasound on tumor growth in mice. |
| Author |
Sicard-Rosenbaum L, Danoff JV, Guthrie JA, Eckhaus MA. |
| Journal |
Phys Ther |
| Volume |
|
| Year |
1998 |
| Abstract |
BACKGROUND AND PURPOSE: A diagnosis of cancer is a contraindication for the use of therapeutic ultrasound (US). Continuous US applied to murine tumors has resulted in larger and heavier tumors. compared with controls. We compared tumor growth using low-power continuous US and energy-matched pulsed US. SUBJECTS: Female C57BL/6 mice (N = 174) were used. METHODS: Animals received. subcutaneous injections of methylcholanthrene tumor cells. The mice were randomly divided into three groups: 60 mice that received low-power continuous US for 5 minutes at 0.75 W/cm2 (LC US group), 63 mice. that received pulsed US for 12.5 minutes at 1.5 W/cm2 (pulsed US group), and 51 mice that served as a control group. The LC and pulsed US groups received equal US energy. Both experimental groups received. 10 treatments of 3-MHz US, which was applied directly over the tumor. The control group received identical handling but no US. After treatment, the tumors were excised, weighed, and measured. A one-way. analysis of variance, followed by Newman-Keuls post hoc testing, was used to analyze the data. RESULTS: Mean tumor weights (in grams) and volumes (in cubic millimeters) were 0.563 g and 564 mm3 for the. LC US group, 0.560 g and 525 mm3 for the pulsed US group, and 0.516 g and 406 mm3 for the control group. CONCLUSION AND DISCUSSION: Reducing total US energy will result in less growth of murine. tumors. When infusing equal energy, continuous and pulsed US will produce similar effects on tumor growth. |
| Title |
Effects of focused ultrasonic radiation on peripheral nerve, with observations on local heating. |
| Author |
Lele PP. |
| Journal |
Exp Neurol |
| Volume |
|
| Year |
1963 |
| Abstract |
The effects of irradiation with a single beam of focused ultrasound at the frequencies of 2.7 Mc, 900 kc, and 600 kc on nerve conduction were studied in over 450 peripheral nerves of the cat, monkey, and man. Giant fibers of the earthworm were used to confirm the results obtained. Irradiation at an adequate intensity caused changes which were progressive with dosage: the first phase, that of enhancement, characterized by increase in the velocity of conduction and in the height of the action potential, was followed by a phase of reversible and differential depression and then that of irreversible depression. Conduction in smaller fibers was affected earlier than that in larger fibers but it was not possible to block the smaller fibers, except for very brief periods, without also blocking the larger fibers. The ultrasonic dosage levels required to produce a given effect were dependent on the medium surrounding the nerve in the region of irradiation. The dosage levels were inversely related to the amount of heat generated in the medium by a single pulse of ultrasound. This and other evidence presented indicates that the observed effects are mediated thermally. All physiological effects of ultrasonic radiation on nerve conduction can be duplicated by application of graded amounts of heat to small segments of nerves. On microscopical examination nerves blocked by ultrasonic irradiation are indistinguishable from those blocked by application of heat. The dosage of ultrasound required to block conduction in subcutaneous nerves by transcutaneous irradiation damages both the overlying skin as well as the underlying muscle. |
| Title |
Effects of frequent ultrasound during pregnancy: A randomised controlled trial. |
| Author |
Newnham JP, Evans SF, Michael CA, Stanley FJ, Landau LI. |
| Journal |
Lancet |
| Volume |
|
| Year |
1993 |
| Abstract |
Despite widespread application of ultrasound imaging and Doppler blood flow studies, the effects of their frequent and.repeated use in pregnancy have not been evaluated in controlled trials. From 2834 women with single pregnancies at 16-20.weeks gestation, 1415 were selected at random to receive ultrasound imaging and continuous-wave Doppler flow studies at.18, 24, 28, 34, and 38 weeks gestation (the intensive group) and 1419 to receive single ultrasound imaging at 18 weeks (the.regular group). Outcome data was obtained from 99% of women who entered the study. The only difference between the two.groups was significantly higher intrauterine growth restriction in the intensive group, when expressed both as birthweight < 10th.centile (relative risk 1.35; 95% confidence interval 1.09 to 1.67; p = 0.006) and birthweight < 3rd centile (relative risk 1.65;.95% confidence intervals 1.09 to 2.49; p = 0.020). While it is possible that this finding was a chance effect, it is also plausible.that frequent exposure to ultrasound may have influenced fetal growth. Repeated prenatal ultrasound imaging and Doppler flow.examinations should be restricted to those women to whom the information is likely to be of clinical benefit. |
| Title |
Effects of frequent ultrasound during pregnancy: A randomised controlled trial. |
| Author |
Newnham JP Evans SF Michael CA Stanley FJ Landau LI. |
| Journal |
Lancet |
| Volume |
|
| Year |
1983 |
| Abstract |
Despite widespread application of ultrasound imaging and Doppler blood flow studies, the effects of their frequent and repeated use in pregnancy have not been evaluated in controlled trials. From 2834 women with single pregnancies at 16-20 weeks gestation, 1415 were selected at random to receive ultrasound imaging and continuous-wave Doppler flow studies at 18, 24, 28, 34, and 38 weeks gestation (the intensive group) and 1419 to receive single ultrasound imaging at 18 weeks (the regular group). Outcome data was obtained from 99% of women who entered the study. The only difference between the two groups was significantly higher intrauterine growth restriction in the intensive group, when expressed both as birthweight <10th centile (relative risk 135; 95% confidence interval 1?09 to 1?67; P=0?006) and birthweight <3rd centile (relative risk 1?65; 95% confidence intervals 1?09 to 2?49; P=0?020). While it is possible that this finding was a chance effect, it is also plausible that frequent exposure to ultrasound may have influenced fetal growth. Repeated prenatal ultrasound imaging and Doppler flow examinations should be restricted to those women to whom the information is likely to be of clinical benefit. |
| Title |
Effects of high intensity sound on electrical conduction in muscle. |
| Author |
Welkowitz W, Fry WJ. |
| Journal |
J Cell Physiol |
| Volume |
|
| Year |
1956 |
| Abstract |
In recent years there has been considerable experimentation on the biological and medical applications of ultrasound. Pertinent literature can be located by reference to bibliographies (Naimark et al., '51; Curry et al., '51) and symposium publications (Matthes and Rech, '49; Giacommi, '50; Fry et al., '53). Some of this research had dealt with effects on muscle tissue (Gersten, '53 and '54; Gary and Gerendas, '49; Harvey, '29). In much of the reported work there is no adequate description of the characteristics of sound field so that quantitative physical interpretations are difficult.
In this paper, the results of a study of the effect of intense acoustic radiation on the propogation of the action potential in muscle tissue are presented. Temperature measureents in the muscle were accomplished during irradiation, and the effect of pure heating on the electrical conduction process was investigated. The results indicate that irreversible suppression of the propagated action potential by the sound can be accomplished in the absence of a damaging temperature level. Although no experimental work to insure that no tension forces existed in the muscle, it is possible to conclude on the basis of indirect observations that no extensive cavitation occurred in the muscle tissue. |
| Title |
Effects of high intensity ultrasound on inorganic solids. |
| Author |
Suslick KS, Casadonte DJ, Green ML, Thompson ME. |
| Journal |
Ultrasonics |
| Volume |
|
| Year |
|
| Abstract |
Ultrasonic irradiation dramatically affects the reactivity of a variety of inorganic solids. We have found, for example, large increases in the rates of intercalation of a wide range of compounds into various layered inorganic solids (such as ZrS2, V2O5, TaS2 and MoO3. High intensity ultrasound also enhances the heterogeneous catalysis of alkene hydrogenation by Ni powders. Scanning electron microscopy reveals that ultrasound has multiple effects on the morphology and surface characteristics of inorganic solids, creating substantial surface damage, increasing surface areas significantly and causing increased particle aggregation. |
| Title |
Effects of high intensity ultrasound on the central nervous system of the cat. |
| Author |
Barnard JW, Fry WJ, Fry FJ, Krumins RF. |
| Journal |
J Comp Neurol |
| Volume |
|
| Year |
1955 |
| Abstract |
The effects of low intensity ultrasound on various tissues of the body have been extensively studied by European investigators (see Matthes and Rech, '49). American workers such as Lehmann ('53) and Herrick ('53) also have used low intensities and these latter authors conclude that the changes produced in the tissues are caused by the heating effects of the sound. Fry ('53) and his co-workers have used high intensity ultrasound in their work. The present paper is a continuation of these later studies, and is an attempt to show histologically the effects of intense ultrasound on the central nervous system.
Earlier histological observations (Wall et al., '51, '53) obtained on animals irradiated at this laboratory indicated that the cell bodies were more susceptible than the fibers. These preliminary results have not been substantiated by further, more detailed studies. In fact the results reported herein show conclusively that the white matter is more readily affected by the ultrasound than the gray matter.
|
| Title |
Effects of high intensity ultrasound on the mechanical response of excised biceps muscle of the frog. |
| Author |
Kelly-Fry E, Fry FJ, Fry WJ. |
| Journal |
Physiology |
| Volume |
|
| Year |
1959 |
| Abstract |
No abstract available. |
| Title |
Effects of high-intensity focused ultrasound in the treatment of experimental neuroblastoma. |
| Author |
Yang R, Reilly CR, REcorla FJ, Sanghvi NT, Fry FJ, Franklin TD, Grosfeld JL. |
| Journal |
J Pediatr Surg |
| Volume |
|
| Year |
1992 |
| Abstract |
This report evaluates the effect of high-intensity focused ultrasound (HIFU) on subcutaneous murine neuroblastoma C1300. HIFU treatment was administered with a focused 4-MHz quartz transducer with a peak intensity of 550 W/cm2. In experiment 1, 60 animals with tumor were divided into four groups. Group I (n = 15) were controls; group II (n = 15) received adriamycin, 5 mg/kg intraperitoneally; group III (n = 15) received HIFU; and group IV (n = 15) received both adriamycin and HIFU. All the animals in groups I and II died of tumor by 35 days. Fifty-three percent (8/15) of mice in group III and 80% (12/15) in group IV were cured with no evidence of tumor (NET) at 200 days. Log-rank statistics showed significant prolongation of survival in the groups III and IV as compared with groups I or II (P < .05). In experiment 2, 45 animals with tumor were divided into three groups. Group I (n = 15) were controls; group II (n = 15) received HIFU; and group III (n = 15) received repeated HIFU. The results showed 47% (7/15) of mice in group II and 67% (10/15) in group III were NET at 200 days. Significant survival prolongation was achieved in groups II and III in comparison with group I (P < .05). In experiment 3, 90 mice received either tumor (n = 60) or saline (n = 30) inoculation in the left flank. On day 5, 45 mice with tumor were treated with HIFU (group I), while the other 15 mice with tumor (group II) had a sham procedure. Nineteen mice in group I were cured with NET (group IA) and 26 had persistent tumor (group IB). The 30 mice receiving saline (without tumor) were treated with either HIFU (group III, N = 15) or a sham procedure (group IV, N = 15). On day 26, all the animals received a second tumor challenge in the right flank. Reduced tumor growth following a second tumor challenge was demonstrated in group IA as compared with other groups (P < .001), implying a stimulation of host tumor immunity following curative HIFU treatment. The data suggest that HIFU may be an alternative modality for the treatment of unresectable neuroblastoma. |
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