Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0037116 (silicosis)
 1,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reactive radicals at the surface of quartz or other SiO2 polymorphs have been studied by EPR in relation to their possible role in pathogenicity. All the examined dusts bear the characteristic radicals of silica ground in air: Si, SiO., SiO.2 (peroxyradical) and O2.- (superoxide ion), but some also show additional spectral lines belonging to other radical forms. Comparison of standard quartz dusts (DQ-12, Min-u-sil 5) with a natural quartz and with what obtained by grinding a very pure quartz crystal indicates that to a higher purity corresponds a higher radical population. Cristobalite and vitreous silica exhibit similar spectra, with larger proportion by respect to quartz, of partially reduced oxygen forms. The reactivity of the silica surface towards O2 and NaClO aqueous solutions are investigated by examining the modification in the EPR spectra induced by these treatments. A possible mechanism for fibrogenicity is proposed whereby, within the activated macrophage, a catalytic reaction occurs between surface functionalities and macrophage oxygen metabolites. This reaction would trigger the abnormal production of fibroblast stimulating factors, ending up with silicosis.
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PMID:Chemical functionalities at the silica surface determining its reactivity when inhaled. Formation and reactivity of surface radicals. 196 71

The occurrence of highly severe silica-related diseases among the resin- and silica-based artificial stone workers was claimed, associated to an extremely short latency. High levels of exposure and intrinsic properties of AS are thought to modulate the development of silicosis and auto-immune diseases. This study compares parent materials and processed dusts, to shed light on changes of AS occurring in the manufacturing process, through an XRF, EPR and XAS investigation. We point out the extremely wide variability of the materials, the occurrence of chemical signatures impressed by the processing techniques, and the unprecedented generation of stable radicals associated to the lysis of the Si-O chemical bond inside the resin coated respirable crystalline silica. These results suggest that the AS processing in industrial stone workshops can create respirable dusts with peculiar physical and chemical properties, to be correlated to the observed clinical evidences.
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PMID:Chemical variability of artificial stone powders in relation to their health effects. 3102 82