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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 65 out of 330
| Title |
Chemical effects of ultrasound on aqueous solutions. Evidence for hydroxyl radicals and hydrogen atoms by spin trapping. |
| Author |
Makino K, Mossoba MM, Riesz P. |
| Journal |
J Am Chem Soc |
| Volume |
|
| Year |
1982 |
| Abstract |
Ultrasound is widely used in diagnosis and therapy in medicine, and the chemical effects of ultrasound on aqueous solutions have long been of interest. Intense ultrasound has been reported to cause chemical damage through the phenomenon of cavitation. Cavitation produces high local instantaneous temperatures and pressures and sonoluminescence. In sonolysis studies of aqueous solutions, it has been proposed that hydroxyl radicals (·OH) and hydrogen atoms (·H) are produced by ultrasound. |
| Title |
Chemical effects of ultrasound on aqueous solutions. Formation of hydroxyl radicals and hydrogen atoms. |
| Author |
Makino K, Mossoba MM, Riesz P. |
| Journal |
J Phys Chem |
| Volume |
|
| Year |
1983 |
| Abstract |
Direct evidence for the formation of ·OH and ·H in the cavitation bubbles produced by ultrasound in argon-saturated aqueous solutions is presented. The methods of spin trapping with 5,5-dimethyl-1-pyrroline 1-oxide (DMPO), 4-[[(1,1-dimethylethyl)imino]methyl]-1-methylpyridinium N-oxide (PYBN), and 2-methyl-N-(4-pyridinylmethylene)-2-propanamine N,N'-dioxide (POBN) combined with ESR were used for the detection of ·OH and ·H. With either DMPO or PYBN, the OH and H adducts were obtained and with POBN, the H adduct was observed. These results were confirmed by sonolysis of D2O solutions containing the same spin traps. By studying the competition reactions for ·OH and ·H between spin traps, DMPO and POBN, and ·OH and ·H scavengers [O2, formate, thiocyanate, benzoate, methanol, ethanol, 1-propanol, 2-methyl-2-propanol, acetone, 2-methyl-2-nitrosopane (MNP)], we obtained further verification for the formation of ·OH and ·H. Sonolysis of aqueous solutions containing DMPO or POBN in the presence of air suppressed formation of H adducts but not that of OH-DMPO. The unusually large effects of acetone and MNP on the spin adduct yields could be explained either by the scavenging of radicals in the gas phase of the cavitation bubbles or by preventing the collapse of the gas bubbles during cavitation and thus reducing radical formation. From the results of the present work, it was inferred that ·OH and ·H are formed in the cavitation bubbles. |
| Title |
Chemistry of ultrasound. III. The irradiative behavior of simple aliphatic amines. |
| Author |
Fayter RG Jr, Spurlock LA. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1974 |
| Abstract |
The ultrasonic irradiation of water was effected under an argon atmosphere with an 800-kHz transducer at several intensities. The rates of hydrogen peroxide formation were followed by spectrophotometric analyses. The results were utilized to relate intensity to reaction rate for standardization purposes. Irradiations of several alkyl amines in aqueous solution or suspension were next accomplished under conditions similar to those applied to pure water. Products included next accomplished under conditions similar tot hose applied to pure water. Products included aldehydes, an alcohol, amines, an N-oxide, methane, ethane, ethylene, carbon monoxide, and hydrogen. The products and their ratios were dependent on the structure of the amine used in the reaction. Reaction rates were only slightly different when an oxygen atmosphere was used instead of argon. The reactivity order for the amines was observed to be primary > secondary > tertiary. Methylamines reacted somewhat faster than did n-butylamine. |
| Title |
Chemopotential by low‐level ultrasound. |
| Author |
Harrison GH, Kubiczek EK. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
1998 |
| Abstract |
Recent laboratory studies have identified a new approach to cancer therapy: the potential of drug action by ultrasound. Both standard chemotherapeutic cytotoxins and relatively nontoxic compounds related to those used in photodynamic tumor therapy are being investigated. Common to most reported investigations has been the use of continuous wave ultrasound at spatial peak, temporal average intensities exceeding 0.5 W/cm2, implying the likelihood of temperature elevation in insonated tissue, and usually involving cytotoxicity from the action of ultrasound alone. On the other hand, for potentiation of chemotherapy using tone‐burst or pulsed ultrasound at spatial average, time average intensities less than 0.3 W/cm2 has been demonstrated [G. H. Harrison, E. K. Balcer‐Kubiczek, and P. L. Gutierrez, Ultrasound Med. Biol. 22, 355–362 (1996)]. Chemopotentiation data will be presented for several biological test systems with emphasis on human prostate tumor cell lines. Mechanistic evidence will be analyzed; fluid streaming and shear stress are likely important determinants of chemopotentiation and the cell membrane can be expected to be an important site in this process. Ultrasound‐induced modification of drug resistance may have important apoptotic links. These factors suggest the importance of treatment‐induced differential expression of membrane‐related genes. |
| Title |
Choice of standard target for medical pulse-echo equipment evaluation. |
| Author |
Lypacewicz G, Hill CR. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1974 |
| Abstract |
Comparisons have been made between plane, spherical, and cylindrical targets in relation to their suitability for quantitative evaluation of the performance of pulse-echo equipment for visualizing tissues. Using fifteen different transducers, with various frequencies and beam-shapes, spherical targets were found to related much more closely (scatter of 12 dB) than did plane targets (40 dB) with the target strength measured in post mortem human liver. |
| Title |
Chorioretinal lesions in rabbits by low-frequency ultrasound. |
| Author |
Karlin DB. |
| Journal |
Am J Ophthalmol |
| Volume |
|
| Year |
1969 |
| Abstract |
No abstract available. |
| Title |
Chromosome aberration and doppler ultrasound. |
| Author |
Franco J,Rydquist R,Kovaleski B. |
| Journal |
Meet AIUM-Denver |
| Volume |
|
| Year |
1971 |
| Abstract |
Macintosh and Davey(Brit. M. J. Oct. 10,1970) reported a considerable increase in the number of chromosome aberrations in human leucocyte cultures exposed to low intensity Doppler ultrasound.
We decided to repeat their experiments. To this effect we obtained peripheral blood leucocytes from a 23 year old non-smoker, non-drinking male college student who had not been on drugs.
We used the DIFCO TC Chromosome Culture kit in the same manner in which we handle our routine cytogenetic studies, except that one bottle was exposed to 2.25 mHz for one hour, while the other was left as a control. Thereafter both bottles were processed in the same manner, i.e., incubation at 37˚C for 72 hours,colchicine treatment and smear preparations.
Coupling between the treatment bottle and the Doptone transducer was accomplished by means of Aquasonic gel and tape.
We counted one hundred metaphase of each preparation and scanned many more. We were searching for chromatid breaks, chromosome fragments and ring chromosomes and expressed their frequency as number of chromosomes aberrations per 100 metaphases.
There was no significant difference in the number of chromatid breaks found in either group( six and eight respectively. No ring chromosomes were found.
As we have been unable to confirm the high incidence of chromosome aberration reportedly induced by an instrument similar to ours, one wonders if other factors than ultrasonic energy were at play in the study reported by Macintosh and Davey.
|
| Title |
Chromosome aberrations after exposure to ultrasound. |
| Author |
Coakley WT, Hughes DE, Slade JS, Laurence KM. |
| Journal |
Br Med J |
| Volume |
|
| Year |
1971 |
| Abstract |
No abstract available. |
| Title |
Chromosome aberrations caused by the effect of ultrasound in the meristematic cells of vicia faba. |
| Author |
Šlotová J, Kaepfel Z, Hrazdira I. |
| Journal |
Biologia Plantarum |
| Volume |
|
| Year |
1967 |
| Abstract |
In our present work the formation of chromosome aberrations has been studied in dependence on the tima interval between sonication and fixation of the primary root tips of Vicia faba. Maximum occurrence of aberrations was recorded immediately after sonication. The results of our experiments pointed to the fact that the frequency of the induced changes was independent on the sonic waves intensity within the range of 0-2—3-0 W/cm2 and on ultrasond treatment duration within the range of 1—20 min.
Studies of the distribution of chromosome abnormalities caused by ultrasound between the large and small chromosomes of theVicia faba meristematic cells in various time intervals showed that the frequency of the aberrations in both chromosome groups was proportional to its total metaphase lengths.
Analysis of the type of aberrations observed in various time intervals after sonication indicated the simultaneous formation of chromosome and chromatide abnormalities.
|
| Title |
Chromosome aberrations induced by an.ultrasonic fetal pulse detector. |
| Author |
Macintosh IJ, Davey DA. |
| Journal |
Br Med J |
| Volume |
|
| Year |
1970 |
| Abstract |
Human blood cultures were exposed to ultrasound from an ultrasonic fetal heart detector for periods of one and two hours. Considerable increases in the number of chromosome aberrations over control values were found. |
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