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Query: UMLS:C0037116 (silicosis)
 1,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Silica granulomas are rare in the skin. Involvement of the regional lymph nodes seems to be unusual. The case of a 35-year-old man with massive diffuse fibrosis of the axilla with multiple foreign body granulomas and involvement of axillary lymph nodes is presented. The lymph nodes exhibit multiple epithelioid cell granulomas and silicotic nodules which are indistinguishable from similar nodules in mediastinal lymph nodes in pulmonary silicosis. It is assumed that the numerous silica particles which were identified by X-ray microanalysis under the scanning electron microscope and recovered from the mineral ash after incineration were accidentally implanted into the skin at the time of an injury 26 years previously. The long delay between silica exposure and granuloma development is a typical feature of these lesions. The possible mechanisms operative in this process are discussed.
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PMID:Unusual silica granulomas of the skin with massive involvement of axillary lymph nodes. 22 32

Silicate substitutes for phosphate in the transitory uncoupling of rat liver mitochondria induced by hydrazine when beta-hydroxy-butyrate is the substrate. Uncoupling is blocked by rutamycin. Just as in the case when phosphate is combined with hydrazine, ATP, ADP, PPi, and Mg++ protect against hydrazine when silicate is combined with hydrazine. A high level of ADP in the absence of added phosphate, but in the presence of silicate, induces a pseudo state three of the mitochondria. Silicate, like sulfate and arsenate which have been reported previously, is activated by the enzymes which mediate oxidative phosphorylation. These results serve to explain a role for silicate in silicosis, black lung disease, and cancer. In addition, since there is suggestive evidence in the literature that lung tissue solubilizes asbestos fibers, these results not only expand the confluence between oxidative phosphorylation and chemical carcinogenesis but are correlated with the synergistic carcinogenicity of asbestos and smoking observed by epidemiologists.
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PMID:The mitochondrial activation of silicate and its role in silicosis, black lung disease and lung cancer. 23 Oct 82

Electron microscopy of femoral lymph nodes of barefooted Ethiopians show the presence of numerous particles of colloid-size and electron-density in the lysosomes of the macrophages in the gland. On diffraction analysis, the particles are found to be amorphous. Elemental microanalysis of the X-ray spectrum indicate the predominance of Si, Al and Fe. In elephantiasics some particles contain silicon alone, presumably silica. The distribution of the Al/Si ratios of the particles in subjects with elephantiasis of the lower legs show a difference from that of non-elephantiasics which is statistically "highly significant" at p less than 0.001. The importance of this as a possible aetiological factor in the disease is discussed. The hypothesis that the disease is discussed. The hypothesis that the disease is a silicosis of the peripheral lymphatics of the lower limbs is supported by the present study.
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PMID:Silica and silicates in femoral lymph nodes of barefooted people in Ethiopia with special reference to elephantiasis of the lower legs. 23 57

Abnormal numbers of birefringent particles have been found in the lungs of seven patients (five vineyard workers, one farmer, and one rural resident) in association with a spectrum of early to late interstitial inflammation and fibrosis. Nodular granulomas of the type seen in silicosis were absent. Scanning electron microscopy and energy dispersive x-ray analysis of 177 individual particles (less than 5 micrometer.) in situ in the lungs of four of the patients showed mostly silicates (notably aluminum, silicon, and potassium), with 5 to 10 per cent silicon dioxide. An analysis of particles less than 5 micrometer. from both vineyard and non-vineyard soil showed lung and soil particles to have a similar composition. The presence of large amounts of silicates in the lung tissues, in association with chronic inflammation and fibrosis, implicates the silicates in the causation of the fibrosis. The silicate deposits may, in large part, be a marker, reflecting a mixture of toxic soil additives or pesticides found in commercial clay silicate products or in dusts from the soil itself. The findings do not exclude lung pathology of a similar nature in regions outside of the farm.
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PMID:Silicate pneumoconiosis of farm workers. 43 58

Four men developed silicosis after sandblasting tombstones for an average of 35 months; 3 of them died an average of 59 months after their first exposure to sandblasting. Lung tissue demonstrated noncaseating granulomas and silicotic nodules involving small arteries and veins in 3 patients and alveolar proteinosis in 2. X-ray energy spectrometry showed primarily elemental silicon in the lung parenchyma. One patient developed lupus erythematosus and another focal glomerulonephritis. Two developed pneumothorax. None had cultural or morphologic evidence of tuberculosis. Pulmonary function studies in all 4 patients revealed a restrictive pattern. Industrial investigations revealed that the patients wore inadequate personal protection equipment and were exposed to 5 times the threshold limit value for respirable silica.
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PMID:Acute silicosis in tombstone sandblasters. 84 57

Pulmonary silicosis usually is characterized by typical hyalinized, concentric nodules as seen under the microscope and in the corresponding roentgenogram. In the case of three foundry workers, lung biopsy specimens contained no nodules. The chest roentgenograms were not suggestive of silicosis. Examination of the biopsy tissue by scanning electron microscopy and energy dispersive x-ray analysis (EDXA) revealed significant (P less than .05) amounts of silicon in the thickened fibrous tissues of septa, pleura, and around blood vessels, enough to permit the diagnosis of silicosis. All three patients had severe functional impairment. It is not clear at this time what factors were responsible for a diffuse distribution of silicon in these cases.
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PMID:A diffuse form of pulmonary silicosis in foundry workers. 98 74

Conventional methods for the detection of foreign material in the lungs are not only difficult but make it impossible to study any relationship between the material and the surrounding tissue. The present study employs energy dispersive x-ray analysis and scanning electron microscopy as the basis of a rapid and accurate method for determining the amount of silicon in the lungs of normal subjects and subjects with silicosis. A statistical evaluation of the data suggests that a silicon/sulfur ratio below 0.2 may be considered normal, whereas, a ratio above 0.3 may be considered to indicate silicosis.
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PMID:Identification of foreign material in lung by energy dispersive x-ray analysis. A new approach to silicosis. 109 63

Several studies indicate that active oxygen species play an important role in the development of pulmonary disease (asbestosis and silicosis) after exposure to mineral dust. The present study was conducted to determine if inhaled fibrogenic minerals induced changes in gene expression and activities of antioxidant enzymes (AOE) in rat lung. Two different fibrogenic minerals were compared, crocidolite, an amphibole asbestos fiber, and cristobalite, a crystalline silicon dioxide particle. Steady-state mRNA levels, immunoreactive protein, and activities of selected AOE were measured in lungs 1-10 days after initiation of exposure and at 14 days after cessation of a 10-day exposure period. Exposure to asbestos resulted in significant increases in steady-state mRNA levels of manganese-containing superoxide dismutase (MnSOD) at 3 and 9 days and of glutathione peroxidase at 6 and 9 days. An increase in steady-state mRNA levels of copper, zinc-containing superoxide dismutase (CuZnSOD), was observed at 6 days. Exposure to asbestos also resulted in overall increased enzyme activities of catalase, glutathione peroxidase and total superoxide dismutase in lung. In contrast, silica caused a dramatic increase in steady-state levels of MnSOD mRNA at all time periods and an increase in glutathione peroxidase mRNA levels at 9 days. Activities of AOE remained unchanged in silica-exposed lungs. In both models, increases in gene expression of MnSOD correlated with increased amounts of MnSOD immunoreactive protein in lung and the pattern and extent of inflammation. These data indicate that the profiles of AOE are dissimilar during the development of experimental asbestosis or silicosis and suggest different mechanisms of lung defense in response to these minerals.
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PMID:Expression of antioxidant enzymes in rat lungs after inhalation of asbestos or silica. 131 5

The prolonged inhalation of silicon powders induces an oxidative stress at respiratory system level, due to the formation of free radicals (FR). Free radical origin is either exogenous (as a result of the chemical structure of powders) or endogenous (result of the endocytosis of silicon powders). Bivalent Fe ions are implied in FR generation, and the substances with Fe chelating and antioxidizing actions block the evolution of silicosis.
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PMID:[Free radicals in silicosis]. 134 7

Slate is a metamorphic rock comprising silica, aluminum silicates, and small amounts of chlorite, hematite, magnetite, and various carbonates. In the United States slate is quarried in Virginia, Pennsylvania, New York, and Vermont. Workers are exposed during mining and processing of the slate and in crushing mills that prepare gravel. We have conducted detailed mineralogic and pathologic studies on the lungs of 12 workers who developed a pneumoconiosis while employed in the quarries of west central Vermont and adjacent areas of New York. Perivascular and peribronchial lesions accompanied by interstitial fibrosis and macules were scattered diffusely in the lungs. The lesions were associated with a variable number of silicotic nodules. Scanning electron microscopy combined with energy-dispersive x-ray spectrometry demonstrated aluminum and silicon-containing particles with variable cationic constituents and silicon alone in a pattern typical of free crystalline quartz. By x-ray diffraction analysis the majority of the mineral particulates were free crystalline quartz and muscovite, an aluminum silicate in the mica group of minerals. Slateworkers are exposed to respirable airborne dust that has the capacity to produce a pneumoconiosis that differs from classic silicosis.
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PMID:Slateworker's pneumoconiosis. 139 38


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