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

We evaluated the effects of daily oral prednisolone therapy on alveolitis parameters and pulmonary function tests over a 6-month period in patients with chronic silicosis. Pulmonary function tests were done in 34 patients, and bronchoalveolar lavage (BAL) was done in 21 of them. Pulmonary function tests showed a significant improvement in lung volumes, FEV1, PEFR, SGaw, DLCO, and PaO2. Analysis of BAL fluid revealed a significant decrease in total cell count. Mean fibronectin and immunoglobulin values in BAL fluid also were lower after treatment, but the change was not statistically significant. No serious side effects were encountered with prednisolone therapy. These results indicate that daily oral prednisolone therapy may suppress the alveolitis in certain patients with chronic silicosis and bring about a significant improvement in lung functions and gas exchange.
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PMID:Effect of prednisolone treatment in chronic silicosis. 200 93

The purposes of this study were (1) to investigate the chronology of events in cellular and biochemical changes thought to be important in the development of silicosis, (2) to relate these to changes in lung function and radiograph, and (3) to evaluate the relation of quartz exposure and retention to individual response leading to early silicosis. Thirty-six sheep were exposed by repeated intratracheal infusion at 10-day intervals to 100 mg Minusil-5 in 100 ml saline (Si group), and 10 sheep were exposed at the same intervals to 100 ml saline (control). All sheep were investigated at 3-month intervals by chest radiograph, lung function, and lung lavage. At month 9, chest radiograph score of parenchymal opacities was significantly increased at 2.8 +/- 0.6 versus 0.4 +/- 0.4 in the Si group (p less than .05), establishing early radiologic silicosis. Lung function was significantly altered with reduction in lung compliance, vital capacity, and diffusion capacity (p less than .05). Lung lavage cellularity revealed significant increase in total cells (X 2.5), macrophages (X3), and neutrophils (X3). Albumin in BAL remained at the control level. Fibronectin production was significantly increased, as was the fibroblast growth activity, without significant change in procollagen 3 at this early stage of disease. Total phospholipids were significantly elevated in the Si-exposed sheep, and the profile demonstrated an increase in all the phospholipid components. Spontaneous release of hydrogen peroxide by alveolar cells was not increased, but in the presence of phorbol myristate acetate (PMA) higher levels of peroxide were found in the quartz-exposed sheep (p less than .05). The cellular and biochemical alterations of lung lavage preceded other changes. At month 12, there were good correlations (r greater than .49, p less than .001) between parameters evaluating related phenomena but poor correlations between measurements evaluating different aspects of the disorder. To investigate the heterogeneity in the individual response of sheep to the same exposure (susceptibility), individual quartz retention levels at month 12 were measured and found to correlate well with individual parameters of disease activity. We concluded that in early silicosis of sheep, cellular and biochemical changes in lung lavage preceded derangements of pulmonary function and radiographic abnormalities. Thereafter, parameters of lung lavage, lung function, and radiograph were significantly interrelated, but for a given exposure the degree of quartz retention appeared to determine the intensity of the silicotic process.
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PMID:Quartz exposure, retention, and early silicosis in sheep. 254 36

The pneumoconioses, interstitial lung disorders resulting from the inhalation of inorganic dusts, are associated with chronic inflammatory processes in the lower respiratory tract. To characterize these inflammatory processes in relation to the pathogenesis of these disorders, we studied 39 nonsmoking individuals with long-term occupational exposures to inorganic dust and functional evidence of interstitial disease (asbestosis, n = 18; coal workers' pneumoconiosis, n = 15; silicosis, n = 6). In all 3 disorders, the inflammation was dominated by alveolar macrophages. Because a common feature of these interstitial lung diseases is concurrent injury and fibrosis of alveolar walls, we assessed whether these alveolar macrophages were spontaneously releasing mediators capable of giving rise to these changes. Alveolar macrophages from the study population were spontaneously releasing increased amounts of superoxide anion and hydrogen peroxide (both p less than 0.01 compared to normals), oxidants capable of injuring lung parenchymal cells. The alveolar macrophages were also spontaneously releasing significantly increased amounts of fibronectin and alveolar macrophage-derived growth factor (both p less than 0.01 compared to normals), mediators that act synergistically to signal fibroblast replication. Taken together, these findings define a major role for the alveolar macrophage in mediating the alveolar wall injury and fibrosis that characterize the common pneumoconioses and suggest that the alveolar macrophage is an important "target" for developing strategies designed to prevent loss of lung function in these individuals.
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PMID:Characterization of the lower respiratory tract inflammation of nonsmoking individuals with interstitial lung disease associated with chronic inhalation of inorganic dusts. 282 69

During the last 10 years our investigations have confirmed that collagen is not the major protein material in the lesions of progressive massive fibrosis of coal workers. In previous studies it was demonstrated that a substance similar in composition to fibrin was an important component in these masses. We report immunohistochemical studies on the lungs of seven coalworkers which show that the complex extracellular material in six of the lesions of massive fibrosis contains fibronectin. Preliminary observations indicate that fibronectin is also present in the lesions of silicosis and asbestosis.
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PMID:Presence of fibronectin in pneumoconiotic lesions. 704 22

The alveolar macrophage (AM) is a critically important cell playing a prominent role in lung inflammation via the production of oxygen radicals, enzymes, arachidonic acid metabolites, and also a large panel of cytokines. Among interstitial lung disorders, silicosis and coal workers' pneumoconiosis (CWP) are the most widespread fibrotic lung diseases. Although their pathophysiology remains incompletely understood, several lines of evidence suggest the participation of cytokines produced by AMs at least in the initiation of the alveolitis. In vitro exposure of AMs (obtained from healthy subjects) to coal dust particles triggered a significant release of tumour necrosis factor (TNF) and interleukin-6, by comparison with titanium dioxide used as a biologically inert control dust. Moreover, it appeared that coal mine dust was more aggressive than similar concentrations of pure silica, suggesting that cytokine secretion induced by coal mine dust was not exclusively related to the presence of silica but resulted from a complex interaction between the different components. In silicosis and CWP, bronchoalveolar lavage showed a large influx of mononuclear phagocytes, with an increased spontaneous production of oxidants, fibronectin, neutrophil chemotactic factor, and also of interleukin-6 and TNF-alpha. This spontaneous cytokine release was associated with an increased cytokine messenger ribonucleic acid (mRNA) expression in the lungs of coal miners.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cytokines and cytokine network in silicosis and coal workers' pneumoconiosis. 765 59

Silicosis is characterized by fibrosing nodular lesions that may eventually develop into progressive massive fibrosis (PMF). Cytokines (interleukin-1beta [IL-1beta], tumor necrosis factor-alpha [TNF-alpha] and growth factors insulin-like growth factor-1 [IGF-1] platelet-derived growth factor [PDGF]) have been implicated in the formation of these lesions. TGF-beta promotes extracellular matrix accumulation by upregulating collagen and fibronectin gene expression, and inhibits matrix degradation by decreasing secretion of proteases and increasing secretion of protease inhibitors. We hypothesized that TGF-beta is associated with matrix deposition and fibrosis in silicosis. To test this hypothesis we studied early and late nodular lesions and PMF (11 cases and two controls) with immunohistochemistry, using rabbit polyclonal antibody to the purified whole molecule of TGF-beta in Bouin's fixed lung tissue. This antibody is reactive with both intra- and extracellular forms of TGF-beta. In the control lungs, small amounts of TGF-beta were present in the bronchial epithelium, macrophages, bronchial and vascular smooth muscle, and bronchial glands. There was minimal to moderate staining in the early silicotic peribronchiolar lesions. In the nodular lesions of silicosis, central hyalinized areas contained the maximum staining for TGF-beta. Fibroblasts in the periphery of the nodular lesions were also positive. In acute silicosis, there was marked staining of hyperplastic alveolar epithelium. Macrophages were markedly positive. In the PMF lesions, large areas of scar tissue contained TGF-beta. These data suggest a major role for TGF-beta in silicosis, particularly in the formation of silicotic nodules and the development of PMF.
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PMID:Transforming growth factor-beta (TGF-beta) in silicosis. 888 10

Interstitial pulmonary fibrosis in developing countries is now diagnosed with an increased frequency. Increased awareness and more frequent availability of computed tomography and fiberoptic bronchoendoscopy have helped in making the diagnosis more often. The spectrum of diseases causing pulmonary fibrosis is broadly similar to that seen in the West. Connective tissue disorders such as systemic sclerosis and rheumatoid arthritis and sarcoidosis are more common causes. Idiopathic fibrosis is seen in approximately half the patients. Pneumoconiosis such as silicosis are also important. Diagnosis is often established on the basis of clinical features and radiologic findings alone. Transbronchial lung biopsy is used as a frequent method to make histologic diagnosis. Some of the causes described from India are rather rare. One of the interesting examples included a patient in whom pulmonary fibrosis was related to his ascent to very high altitude. Extreme cold, solar radiation, and other factors complicating low atmospheric oxygen pressure were implicated as causative factors. Lung fibrosis, secondary to exposure to toxic gas (methyl isocyanate), is reported in survivors of the Bhopal gas leakage tragedy of 1984. Serial bronchoalveolar studies have show elevated fibronectin levels and the presence of macrophage-neutrophilic exudate in the lavage fluid.
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PMID:Incidence and recognition of interstitial pulmonary fibrosis in developing countries. 933 41

Exposure to quartz induces pulmonary inflammation and development of fibrosis. In order to study the fibrosing process, we investigated morphology, function and phenotype of alveolar (AMs) and interstitial (IMs) macrophages at an early stage of fibrosis in rats. Rats were exposed by intratracheal instillations of 10 mg quartz (n=8) or saline (n=8) and studied 3 months later. AMs were obtained by bronchoalveolar lavage and IMs by mechanical fragmentation, followed by enzymatic digestion of lung tissue. Histology revealed subacute silicosis, with early focal fibrosis and alveolar lipoproteinosis. AM quartz exposure increased phagocytic activity and expression of major histocompatibility complex (MHC) Ia antigens, the latter being associated with cellular antigen presenting capacity. IM had an even more pronounced expression of MHC than AM after quartz exposure. Both macrophage fractions had a higher expression of OX-42 (complement receptor 3, CR3) than controls, but the increase in the IM fraction might be explained by the remaining AM in the IM fraction. Exposed AM adhered less to extracellular matrix components (vitronectin and fibronectin) than controls. In contrast, the adhesion of IM to vitronectin increased after exposure. Besides increased adhesion, the effects on IM were scarce. Our results therefore do not support the hypothesis that IM has a key role in the process of inflammation, including fibrosis.
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PMID:Rat alveolar and interstitial macrophages in the fibrosing stage following quartz exposure. 1100 90

The study has defined criteria for the concomitant development of tuberculosis as secondary to silicosis. Factorial and discriminant analyses identified the most significant factors of immune homeostasis in silicotuberculosis. The major signs of possible development of tuberculosis in the presence of silicosis are the elevated levels of total IgE and IgG, fibronectin; the cells expressing CD4+ and CD20+ markers; and the decreased concentration of the mucinic antigen 3EG5. The findings were used to construct models of immunity in tuberculosis, silicosis, and silicotuberculosis. The use of a complex of immunological studies promoted the better early diagnosis of silicotuberculosis.
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PMID:[Immunological parameters in the diagnosis of silicotuberculosis]. 1531 28

Crystal micro-morphology and dimension of silica particles could be responsible for the high prevalence of silicosis as recently found among goldsmiths. In the present study we investigated two samples of silica particles with different surface sizes and shapes for their capacity to induce changes in ECM component production. In addition we investigated if their different effects could be related to cytotoxicity and apoptotic effects. Human bronchial epithelial cells were cultured with or without a sample of Silica used for casting gold jewellery, named in our experiments Silica P or a commercial sample of Silica with different physical and chemical properties, named in our experiments Silica F. After 48 h of exposure PCR analysis determined levels of several matrix components. As induction of the apoptosis cascade, annexin assay, caspase 3 activity and cellular cytoxicity by MTT assay were assayed. Silica F promoted fibronectin, MMP12, tenascin C and Integrins b5 gene expressions more than Silica P. Silica P stimulated more TGFß1 and its TGFßR1 receptor than Silica F. Cytotoxic effects were induced by the two samples of Silica. On the contrary, no alteration in classic apoptotic marker protein expression was observed in presence of either Silica F or Silica P, suggesting silica particles affect ECM production and metalloproteases through a mechanism that does not involve apoptotic activation. Different Silica micromorphology and TGFß signal pathway are linked to lung fibrotic effects but the potential role Silica in apoptotic and toxic reaction remains to be ascertained.
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PMID:Silica particle size and shape: in vitro effects on extracellular matrix metabolism and viability of human bronchial epithelial cells. 2324 Nov 18


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