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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 53 out of 330
| Title |
Biological effects in laboratory animals. |
| Author |
O'Brien WD Jr.(Nyborg WL, Ziskin MC eds.) |
| Journal |
Book Chapter |
| Volume |
|
| Year |
1985 |
| Abstract |
In animal studies, attention has been given to a number of ultrasonically induced biological effect end-points. One can think of these as being classified into one of two general categories: structural or functional alterations. A change in biological material that is determined through histologic means is considered a morphologic or structural alteration. Most ultrasonically induced structural alterations have been assessed by light microscopy. A biological effect which is assessed by a change in some biochemical level, pH or activity is considered a functional alteration. In general, relatively high ultrasonic intensity levels are required to produce a structural alteration; at lower levels, where structural alterations are not detectable, functional alterations have been observed.
In the context of a structural or functional alteration, there are various degrees to which the experimental data are conflicting. One category of observations deals mainly with structural alterations (usually termed "esions" here) of biological tissues produced by quite high levels of ultrasonic energy. Here there is no conflict in terms of whether or not a specific effect occurred but there are conflicting viewpoints in terms of the fundamental mechanism or mechanisms responsible. At lower ultrasonic energy levels, usually within the therapeutic range, there are conflicting viewpoints as to whether, or to what degree, a structural alteration occurred. And, for a third general category, at ultrasonic energy levels lower than the therapeutic range, sometimes at diagnostic levels, there are no indications of structural changes and there are very conflicting data as to whether a functional alteration occurred. |
| Title |
Biological effects of acoustic cavitation. |
| Author |
Frizzell LA. (Suslick K. ed.) |
| Journal |
Book Chapter |
| Volume |
|
| Year |
1988 |
| Abstract |
Introduction: Acoustically induced cavitation has numerous beneficial uses in industry and laboratories. Ultrasonic cleaning, which depends directly upon acoustic cavitation, has been one of the primary industrial uses of ultrasound for many years. Cell disruptors generate acoustic outputs sufficient to induce cavitation, which breaks up biological cells so that their contents may be used or analyzed. The use of acoustic cavitation to induce chemical reactions is a more recent and growing application that is discussed at length in Chapter 6. This chapter deals with the biological effects of ultrasonically induced cavitation and its potential for harm in clinical applications of ultrasound. See Chapter 8 for a discussion of other mechanisms involved in the production of biological effects. |
| Title |
Biological effects of diagnostic ultrasound: A review. |
| Author |
Baker ML, Dalrymple GV. |
| Journal |
Radiology |
| Volume |
|
| Year |
1978 |
| Abstract |
Biological effects from experimental ultrasound studies, such as chromosome aberrations and retardation of growth, have been recorded but mostly at levels far in excess of diagnostic intensity. The data surveyed in this review suggests that there is apparently little or no danger associated with diagnostic ultrasound exposure at clinical levels. |
| Title |
Biological effects of low-temporal, average-intensity, pulsed ultrasound. |
| Author |
Carstensen EL. |
| Journal |
Bioelectromagnetics |
| Volume |
|
| Year |
1982 |
| Abstract |
Studies with both plant and animal tissues show that, when the tissues contain micron-sized, stabilized gas bodies, pulsed ultrasound can produce damage at very low time-averaged intensities. However, it is the temporal peak intensity rather than the time-averaged intensity that is closely correlated with the effects observed. The data suggest that there may be thresholds for damage at peak intensities within an order of magnitude of 10 W/cm2. |
| Title |
Biological effects of shock waves: Cavitation by shock waves in piglet liver. |
| Author |
Delius M, Denk R, Berding C, Liebich HG, Jordan M, Brendel W. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1990 |
| Abstract |
Shock waves are known to generate cavitation in vitro. In vivo, extracorporeal shock waves may cause haemorrhages in tissues. Two types of changes were detected by conventional, real-time B-scan ultrasound when shock waves were administered to 5 piglet livers in vivo: transient changes consisting of bright signals in intrahepatic branches of the portal vein and tributaries of the hepatic vein, presumed to originate from gas bubbles, and stationary changes consisting of brightening of the area along the long axis of the high pressure field, presumed to indicate an increased number of gas-filled bubbles in this area. Transient changes appeared from the start of shock wave administration; bright signals were seen in liver vessels for several hundred microseconds before they were flushed away with the blood flow. Stationary changes appeared later, increased in intensity over several hundred shock waves and persisted for minutes after cessation of shock wave administration. Both types of signals were interpreted as direct evidence that lithotripter shock waves generated cavitation in vivo. Similar signals were received in the partly degassed water of the lithotripter tub. At autopsy of the piglets, focal intralobular haemorrhages and thrombi of portal veins were detected in the shock wave path. The occurrence of cavitation and tissue damage in the same gross area suggests that cavitation might be involved in the generation of tissue damage by shock waves. |
| Title |
Biological effects of shock waves: In vivo effect of high energy pulses on rabbit bone. |
| Author |
Delius M, Draenert K, Diek YA, Draenert Y. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1995 |
| Abstract |
Extracorporeal shock waves have recently been introduced to treat pseudarthrosis and aseptic bone necrosis. Only little information exists up to now about the morphological effects of shock waves on normal bone. To study both their acute effect on bone and their long-term effect on its remodelling, 1500 shock waves generated with a Dornier XL1 experimental electrohydraulic lithotripter were applied at 27.5 kV to 19 rabbits divided into five groups. Changes were evaluated after 6, 11, 41, 59 and 85 days. The discharges were focused to the right femur 1 cm above the knee joint. Bone remodelling was assessed in four groups by four-colour fluorescent labelling with labels administered sequentially over 8-day periods during the first month after shock-wave application. Radiographs were taken at dissection to detect fractures. As a result, shock waves were found to induce periosteal detachment with subperiosteal haemorrhages and to press marrow contents out of the medullary cavity. In the medullary cavity, diffuse haemorrhages, haematomas and foci of fractured and displaced bony trabeculae were found. The bone cortex and the knee joint were normal. Radiographs showed lucencies in the marrow but no fractures. During the weeks following shock-wave application, there was intense apposition of new cortical bone resulting in considerable cortical thickening while trabecular remodelling in the medullary cavity was only minor. The displacement of bony trabeculae and marrow contents point to the action of cavitation as the major mechanism of shockwave damage to bone.
|
| Title |
Biological effects of shock waves: Induction of arrhythmia in piglet hearts. |
| Author |
Delius M Hoffman E Steinbeck G Conzen P. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1994 |
| Abstract |
During lithotripsy by electrohydraulic or electromagnetic lithotripters, the application of extracorporeal shock waves has to be synchronized with the electrocardiogram to reduce the induction of arrhythmias. The relation between the refractory period of the cardiac cycle and arrhythmia induction by shock waves, and the underlying mechanism have so far not been examined. In this experiment, the cardiac response to shock waves administered at 20 kV by an electrohydraulic lithotripter was assessed in nine piglets. The focus was positioned 5, 10 and 15 cm caudal to the apex of the left ventricle, and in some piglets also at the apex. The interval following the R-wave was determined during which the heart was refractory to shock wave stimulation by either single discharges or shock-wave bursts, i.e., groups of discharges separated by 10 ms intervals. This mechanical refractory period was compared to its electrical counterpart, which was determined by transvenous intracardiac atrial stimulation. As a result, mechanical refractory periods following the R-wave were at 5 cm distance 60 ms for single discharges and 70 ms for bursts (medians; range 10-180 ms); both stimulation modes were highly correlated (r = 0.88). While a similar result was obtained with the focus positioned directly at the cardiac apex, at 10 cm distance from it, bursts elicited a cardiac response significantly more often (in nine vs. two piglets). At 15 cm distance, no response was obtained at all. Both mechanical and electrical atrial refractory periods were in a similar range. |
| Title |
Biological effects of shock waves: Kidney damage by shock waves in dogs--dose dependence. |
| Author |
Delius M, Enders G, Xuan Z, Liebich H-G, Brendel W. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1988 |
| Abstract |
The effect of shock waves on normal canine kidneys was examined in three groups of dogs whose right kidneys were exposed to 500, 1500, or 3000 shock waves. Autopsy was performed 24-30 h later. The kidneys were enlarged with haemorrhages in the outer and inner renal capsule and intraparenchymally. Macroscopically intraparenchymal haemorrhages were restricted to the high pressure field of the shock wave and consisted of haematomas up to 18 mm diameter (most frequently 6 mm or less) and diffuse haemorrhages. Histologically, haemorrhages were shown to originate from interlobular and arcuate veins. Venous thrombosis, tubular dilatation, and diffuse interstitial haemorrhage occurred in the same area. The number of haematomas was larger, and diffuse haemorrhages were more extended after the application of 1500 and 3000 than after 500 shock waves. No difference was seen between 1500 and 3000 shock waves. |
| Title |
Biological effects of shock waves: Kidney haemorrhage by shock waves in dogs--administration rate dependence. |
| Author |
Delius M, Jordan M, Eizenhoefer H, Marlinghaus E, Heine G, Liebich H-G, Brendel W. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1988 |
| Abstract |
The effect of shock waves on normal canine kidneys was examined in two groups of dogs whose right kidneys were exposed to 3000 shock waves generated with 20 kV and 40 nF in a Dornier HM II lithotripter. The groups differed only in the rate of shock wave administration which was 100 and 1 per second, respectively. Autopsy was performed 24 to 30 h later. Macroscopically and histologically, significantly more haemorrhages occurred in the kidney parenchyma if shock waves were administered at a rate of 100 waves per second. Haemorrhages were diffuse, the outer medulla was most heavily affected. The results show that kidney damage is dependent on the rate of shock wave administration. They argue against a direct shock wave effect and favor cavitation as the mechanism of shock wave damage although thermal effects cannot be excluded. |
| Title |
Biological effects of shock waves: Lung hemorrhage by shock waves in dogs--pressure dependence. |
| Author |
Delius M, Enders G, Heine G, Stark J, Remberger K, Brendel W. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1987 |
| Abstract |
The most serious side effect observed during the destruction of gallstones by shock waves in dogs was lung bleeding. To determine the conditions leading to lung damage, pressure probes were implanted into dogs between the lung and the diaphragm. The distance between the lung and the focal point of the pressure field was determined at which 1000 shock waves caused no more lung hemorrhage. On the long axis it is greater than 15 cm and perpendicular to the long axis it is 4 cm. Shock wave pressures over 2 MPa could be administered safely, whereas a pressure of 10 MPa caused bleedings in beagles, but probably not in boxers. |
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