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)

Published data suggest that particle charge could be related to its toxicity. Respirable particles containing silica were therefore collected in foundries and their charge measured. These particles carried high levels of positive charge that were related to low humidity. Incubating these particles with pulmonary macrophages from mice produced detectable activities of collagenase, a precursor of silicosis. These experiments confirm that the toxicity of silica particles is likely to be because of the positive charge they carry.
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PMID:What makes silica toxic? 131 80

Inflammatory cells and lymphocyte populations were examined in the bronchoalveolar lavage (BAL) fluid, lung tissues, and peripheral blood from rats at various times after the intratracheal instillation of silica. In lavage fluid, there was a rapid initial increase in the percentage and number of polymorphonuclear leukocytes (PMN), which slowly decreased during the course of the experiment. In addition, compared to controls, there was an increased number and percentage of lymphocytes throughout the 75 days of the experiment. The lymphocytic populations, which were determined by an indirect immunofluorescence method with monoclonal antibodies to lymphocyte surface markers, showed a predominance of the T-helper phenotype from Day 14 through the end of the experiment (Day 75). The number of PMNs obtained from collagenase digest of the lung was increased over control levels up to Day 7 after silica administration and remained at a relatively constant level until Day 14, after which time they decreased slightly in number. The total number of lymphocytes peaked on Day 14, with cells of the T-helper phenotype predominating after this time. In the peripheral blood, T-helper cells from silicotic rats were significantly increased over control rats on Days 7 and 14 but returned to normal control values after this time. The lymphocyte subsets in the BAL, but not in the peripheral blood, more closely reflect the lymphocyte patterns in the lung. The results of these experiments suggest that T-helper cells may play an important role in the inflammatory-fibrotic events in the lungs of rats with silicosis.
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PMID:Lymphocyte populations in lung tissue, bronchoalveolar lavage fluid, and peripheral blood in rats at various times during the development of silicosis. 291 50

We have evaluated, in an experimental model of silicosis in guinea pigs, if the presence of collagenolytic activity in bronchoalveolar lavage (BAL) fluid reflects the collagen catabolism in lung parenchyma. We measured simultaneously BAL collagenase activity, using as substrate [3H]type I collagen, and lung collagenolytic activity by the tissue pellet assay. Animals (n = 30) were instilled intratracheally with 50 mg of quartz DQ-12 and sacrificed 15, 30, and 60 days after silica administration. Guinea pigs instilled with saline solution were used as controls. Our results showed that lung parenchymal collagenolytic activity was present in all experimental and normal guinea pigs. There were no statistical differences between silicotic and normal animals at 15 and 30 days. At 60 days, however, a significant decrease in tissue collagenolytic activity was observed in silicotic animals (161 +/- 100 vs. 400 +/- 152 units of collagenase activity; p < 0.001). In contrast, BAL collagenolytic activity was revealed only in 7 of 10 silicotic animals at 15 days and 30 days, and in 4 of 10 at 60 days. Normal guinea pigs did not exhibit BAL collagenase activity. BAL and tissue collagenase activity from each experimental animal were analyzed by straight line regression and no significant relationship was observed (r = 0.082; p = 0.87). This suggests that BAL collagenolytic activity does not reflect lung tissue collagen turnover.
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PMID:Comparison between lung parenchyma and bronchoalveolar lavage collagenolytic activity. 842 65

Long-term exposure to silica (SiO2) may induce silicosis as well as extrapulmonary diseases such as scleroderma. Infiltration of mononuclear cells and release of proinflammatory cytokines from these cells have been suggested to play a role in the development of inflammatory and immunological events typical of scleroderma as well as of silica-induced scleroderma. We showed that silica is able to directly activate cytokine expression in blood monocytes, collagenase expression in cultured dermal fibroblasts and ICAM-1 expression in human dermal microvascular endothelial cells. In the study reported here we found that silica and TNFalpha induce mRNA and protein of the chemokines RANTES and MCP-1 in endothelial cells. In addition, we demonstrated that culture supernatants of silica-treated endothelial cells are chemotactic for mononuclear cells from peripheral blood, suggesting that activation of endothelial cells may contribute to the chemotactic gradient necessary for extravasation of inflammatory blood cells into the surrounding tissue found in early scleroderma. However, a polyclonal anti-RANTES antibody failed to block chemotaxis suggesting that other proteins are involved in this phenomenon. We also studied the expression of RANTES in situ in the skin of systemic sclerosis patients and of healthy individuals. We found abundant RANTES mRNA expression in the skin of SSc patients, whereas in control skin no expression was found. From our data we conclude that RANTES and MCP-1 induction by silica may be an initiating event in inflammatory infiltration, whereas TNFalpha-mediated inflammation may propagate the disease more efficiently.
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PMID:Chemokine release from activated human dermal microvascular endothelial cells--implications for the pathophysiology of scleroderma? 1096 58