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2575012 
Journal Article 
Abstract 
Role of surface characteristics in the production of reactive oxygen species by ambient crystalline silica and engineered silica particles 
Premasekharan, G; Man, HJayFor; Leppert, V 
2008 
Yes 
Free Radical Biology and Medicine
ISSN: 0891-5849
EISSN: 1873-4596 
45 
Suppl. 
S22-S22 
English 
WOS:000260867900053 
is part of a larger document 3452652 SFRBM's 15th Annual Meeting: Program and Abstracts
Inhalation of particulate matter induces a variety of respiratory diseases in humans. the rapid development of engineered particles has also added a new potential source of environmental and workplace airborne toxic substances. the mechanism of both engineered and ambient particulate induced toxicity likely involves oxidative reactions. Our main purpose was to determine whether nonenzymatic reactions of transition metal impurities on particle surfaces enhance hydrogen peroxide production by the macrophage respiratory burst, resulting in lipid peroxidation of the macrophage plasma membrane. in this study, the THP-1 human macrophage cell line was exposed in vitro to ambient crystalline silica particles of mean diameter 2.5 μm; with the exposure doses, starting from 10µg/ml/106 cells, in the range of ambient particle exposure. Particles were characterized for size distribution, morphology and trace metals using the scanning electron microscope and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). They were surface treated to remove metals and their metal composition analyzed using energy dispersive X-ray spectrometry and ICP-MS. the intensity of the macrophage respiratory burst, measured by nitroblue tetrazolium assay, showed elevated response in untreated silica particles even at noncytotoxic doses. Lipid peroxidation products, assessed by both 8-isoprostane and diphenyl-1-pyrenylphosphine assays, showed elevated levels for untreated particles compared to treated particles, indicating an involvement of trace metals in their production. Our most recent work with iron-doped engineered silica particles also showed a strong release of lipid peroxides compared to untreated ambient silica particles. These results suggest that trace metal contaminants play an important role in both ambient and engineered particle-induced inflammatory response in the lungs. 
Society for Free Radical Biology and Medicine 15th Annual Meeting 
Indianapolis, IN 
November 19-23, 2008