Document Detail

Major factors involved in the inhibition of ultrasound-induced free radical production and cell killing by pre-sonication incubation or by high cell density.
MedLine Citation:
PMID:  15590309     Owner:  NLM     Status:  MEDLINE    
To identify the factors involved in the inhibition of ultrasound (US)-induced free radical production and cell killing by pre-sonication incubation or by high cell density, we used different densities of U937 cells, and with (up to 2 h) or without pre-sonication incubations, the cell suspensions were exposed to 1 MHz US (10% duty factor at 100 Hz pulse rate; intensities 0.1-0.5 W/cm(2) for 1 min). The intensity 0.3 W/cm(2) was used for cell killing experiments and 0.5 W/cm(2) for free radical experiments. Free radical production was determined by electron paramagnetic resonance (EPR)-spin trapping with DMPO while cell killing was determined by assays for lysis, loss of cell viability, apoptosis and necrosis. The results show that at higher cell densities, CO(2) in the medium rapidly increased, with shorter pre-sonication incubation required to attain complete inhibition of both free radical production and cell killing. Cell killing at 0.3 W/cm(2) and free radical production at 0.5 W/cm(2) were both inhibited at 10 million cells/ml without incubation, and at 2 million cells/ml incubated for 2 h before sonication. Level of CO(2) alone could not account for the inhibition; consumption of gases in the medium is also considered in the inhibitory effect of pre-sonication, while suppression of cavitational activities due to the "viscosity effect" is considered a more important factor in the inhibition by high cell density.
Loreto B Feril; Takashi Kondo
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ultrasonics sonochemistry     Volume:  12     ISSN:  1350-4177     ISO Abbreviation:  Ultrason Sonochem     Publication Date:  2005 Apr 
Date Detail:
Created Date:  2004-12-13     Completed Date:  2005-02-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9433356     Medline TA:  Ultrason Sonochem     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  353-7     Citation Subset:  IM    
Faculty of Medicine, Department of Radiological Sciences, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
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MeSH Terms
Carbon Dioxide / metabolism
Cell Count
Cell Line, Tumor
Cell Survival / radiation effects
Electron Spin Resonance Spectroscopy
Free Radicals / chemistry*,  radiation effects*
Leukemia, Myelomonocytic, Acute / pathology
Reg. No./Substance:
0/Free Radicals; 124-38-9/Carbon Dioxide

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