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

The paper reports a case of silicosis associated with idiopathic unilateral hyperlucent lung--MacLeod's disease (ML)--in a 65-year old miner. ML had not been diagnosed before this clinical observation and the patient had been exposed to silica dust for about 15 years as a truck operator in water supply tunnelling work in central Italy. Impaired ventilatory function due to left pulmonary dystrophy was the favouring or even the causal factor of dust accumulation in the functionally active right lung and of the tissue reaction to the dust, leading to interstitial fibrosis. A radiological diagnosis of p 1/0 pneumoconiosis was made according to the 1980 International Labour Office classification. Clinical, radiological and functional findings indicated the presence of respiratory failure as a result of the sum of silicotic and dystrophic lesions. Two combined pulmonary scintigraphic examinations with Tc99 perfusional and mTc-DPTA inhalatory methods revealed peculiar alterations: absence of ventilation associated with severe vascular impairment in the left lung, inequality of the ventilation/perfusion rate, due to pneumoconiosis, in the right lung. MacLeod's disease is rare, but must be considered as a mandatory contra-indication for work involving dust exposure risk since it is one of the predisposing factors which can cause an occupational disease even if environmental exposure standards are observed.
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PMID:[Pulmonary silicosis associated with MacLeod syndrome: a case report]. 811 52

Experiments on white rats proved that the silicotic pulmonary changes slowed with the tails periodically immersed into iodine solution. Those pulmonary changes were due to inhalation of quartzite dust and especially due to intratracheal administration of standardized quartz dust DQ12. Influenced by inhalation of dust containing quartz, the rats demonstrated characteristic alterations in cytologic features of bronchial and alveolar lavage water. The "iodine baths" also declined those alterations, that may prove higher resistance of pulmonary macrophages to cytotoxic effects of quartz. This hypothesis finds a support in experiments with culture of rat peritoneal macrophages. If incubated in a medium with low iodine concentrations and subsequently washed off, the macrophages demonstrate lower incidence of cytotoxic effects due to the next incubation with particles of DQ12. The macrophage's higher resistance against cytotoxic agents is believed to result directly in antisilicotic effect of iodine, so "iodine baths" could be recommended for pathogenetic therapy and medical prophylaxis of silicosis.
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PMID:[Percutaneous effects of iodine inhibit the development of experimental silicosis]. 896 87

The authors studied role of antioxidant enzymes--superoxide dismutase and catalase--in pathogenesis of experimental pulmonary silicosis in rats. Experimental silicosis was induced by intratracheal administration of quartz dust, 20 mg. Aerosols of superoxide dismutase and catalase water solutions were inhaled twice a week during first month and 5 times a week over the next 1.5 months. The results perfectly match the previous data proving quartz dust to stimulate granulocytes' release of extracellular superoxide radicals and hydrogen peroxide. The research results also demonstrate important role of agents moving one electron for reduction of oxygen in silicosis pathogenesis.
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PMID:[The influence of superoxide dismutase and catalase on the course of the pathological process in the lungs in experimental silicosis]. 985 41

The exposure to silica and related substances such as silicate (e.g. chrysotile asbestos; 3MgO.2SiO2.H2O) or silicone (-R2Si-O-)n, used in plastic surgery, has been known to induce autoimmune diseases. The pathogenesis of autoimmunity induced by such environmental factors, however, needs to be clarified. On the other hand, details about the relationship between autoimmunity and defective functioning of the Fas-Fas ligand system have been analyzed. In this report, we intend to summarize our results which suggest a suppressed apoptosis through the Fas-Fas ligand system in silicosis patients, and to speculate on the effects of silica on inappropriate cell survival which could induce the development of autoimmune reactions. We observed elevated levels of serum sFas and an increased expression of sFas mRNA in silicosis patients. sFas instead of membranous Fas binds competitively to the Fas ligand, and consequently, reduces the apoptosis of Fas positive cells. In addition, we observed polyclonal activation of human T cells by silica and silicate in vitro. In such cases, many autoreactive clones could be activated simultaneously. From these results, silica and silicate could play an important role in inducing autoimmune reactions by (1) repeated polyclonal activation of human T cells and (2) the suppression of apoptosis inducing the release of sFas into the sera of the patients.
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PMID:[Fas-Fas ligand system in silicosis patients]. 1098 Nov 80

Iron is a vital element in life. Because of the insolubility of iron oxides and sulfides the implication is that dissolved iron was fairly abundant and that oxygen and sulfide were rare in the atmosphere and ocean. Iron and its compounds present as pollutants in the atmosphere can cause deleterious effects to humans, animals, and materials. Analyses of urban air samples show that the iron content averages 1.6 microg/m(3), with the iron and steel industry probably the most likely source of emission. Iron is a natural component of soils and its concentration can be influenced by some industries. Iron concentration in surface water varies greatly, from 61 ppm to 2680 ppm. The disposition of iron in the human body is regulated by a complex mechanism to maintain homeostasis. Iron concentrations in body tissues must be tightly regulated because excessive iron leads to tissue damage, as a result of formation of free radicals. Iron has the capacity to accept and donate electrons readily. The content of body iron is regulated primarily by absorption since humans have no physiological mechanism by which excess iron is excreted. Iron has been identified as a component of asbestos and other mineral and synthetic fibers. Inhalation of iron oxide fumes or dust by workers in the metal industries may result in deposition of iron particles in lungs, producing an X-ray appearance resembling silicosis. During the last decades efforts regarding dietary iron supply focused mostly on the prevention of deficiencies, especially during growth and pregnancy. The chemical form of the iron influences absorption, as do interrelationships with other dietary components.
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PMID:Essential metals--case study on iron. 1291 52

This study was designed to document the effect that wet abrasive blasting has on reducing worker exposure to crystalline silica, which has been associated with silicosis and premature death. In this study, worker exposure to respirable crystalline silica was monitored during wet abrasive blasting on the exterior walls of a parking garage to remove surface concrete and expose the underlying aggregate. In this process a wet sand mix comprised of 80% dry sand and 20% water was used. Sampling and analysis revealed that the geometric mean respirable quartz concentration was 0.2 mg/m(3) for workers conducting abrasive blasting and 0.06 mg/m(3) for helpers. When abrasive blasting was conducted in areas that apparently had reduced natural ventilation, dust exposures appeared to increase. When compared with other published data, this case study suggests that wet abrasive blasting causes less exposure to crystalline silica than dry abrasive blasting.
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PMID:Control technology for crystalline silica exposures in construction: wet abrasive blasting. 1520 68

Abrasive blasting with silica sand has long been associated with silicosis. Alternatives to sand are being used increasingly. While NIOSH has done extensive investigations of the respiratory effects of the substitutes for sand, the ergonomic effects of the substitutes have not been examined. Too often, hazards are shifted, and technologies that might save workers' lungs could do so at the expense of their musculoskeletal systems. Hence, the objective of this study was to examine the ergonomic effects of alternatives to sand. Multiple methods, both qualitative and quantitative, were used to yield numerous kinds of data for the analysis of exposures to abrasive blasters. PATH, a method for quantifying ergonomic exposure in non-routine work, was combined with interviews with workers, biomechanical modeling and noise level readings to assess the ergonomics of two abrasive blasting operations: high-pressure water and steel shot. Advantages and disadvantages of each medium are discussed. High-pressure water was slightly less ergonomically stressful, environmentally cleaner, much quieter and less dusty that steel shot, and it was reported to be slower on those tasks where both media could be used.
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PMID:Ergonomics of abrasive blasting: a comparison of high pressure water and steel shot. 1628 59

Silica particle-associated inflammation is implicated in the genesis of several pulmonary diseases, including silicosis and lung cancer. In this study we investigated the role of phosphatidylcholine-specific phospholipase C (PC-PLC) in silica-stimulated induction of TNF-alpha and IL-1beta and how PC-PLC activity is regulated by silica in a rat alveolar macrophage model. We demonstrated that inhibition of PC-PLC, which was achieved with tricychodecan-9-yl-xanthate (D609), blocked the silica-stimulated induction of TNF-alpha and IL-1beta in alveolar macrophage, suggesting that PC-PLC is involved in the silica-associated inflammatory response. PC-PLC activity was increased significantly by silica exposure, and this could be inhibited by MnTBAP, which catalyzes both the dismutation of O2.- to O2 and H2O2 and the dismutation of H2O2 to O2 and H2O, revealing that PC-PLC activity is regulated in a redox-dependent manner. This is further confirmed by the finding that PC-PLC activity was increased by exogenous H2O2. The intracellular calcium chelator BAPTA blocked the H2O2-increased PC-PLC activity, while the calcium ionophore, A23187, enhanced PC-PLC activity. The data indicate that PC-PLC plays critical roles in the silica-associated inflammatory response and that PC-PLC is regulated through redox- and calcium-dependent manners in alveolar macrophages.
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PMID:Silica induces macrophage cytokines through phosphatidylcholine-specific phospholipase C with hydrogen peroxide. 1715 58

Multiple different types of anterior mediastinal masses may be encountered on computed tomography (CT) imaging, and many of these lesions are neoplastic in etiology. These include masses arising from the thymus, thyroid and parathyroid glands, as well as lymph nodes, pericardium, and vessels and nerves. Often, the CT attenuation of the mass can be helpful in narrowing down the differential diagnosis, and attenuation values suggesting fat, water or calcium may suggest certain diagnoses; significant enhancement of the mass with intravenous contrast may also be a helpful feature. Lesions with fatty attenuation include teratomas, thymolipomas and Morgagni hernias. Lesions that may manifest the attenuation of water include pericardial and thymic cysts, abscesses, and lymphangiomas, as well as neurogenic and germ cell tumors. Multiple types of lesions may contain calcium, including thyroid goiters and cancers, thymomas, thymic carcinomas and carcinoids, treated lymphoma, germ cell tumors, parathyroid adenomas, and lymph nodes involved with silicosis, sarcoid, tuberculosis, fungal diseases and pneumocystis. Contrast enhancement may be seen in lesions of vascular origin and in vascular neoplasms, such as parathyroid adenomas and Castleman's disease. In addition to CT attenuation values, the exact location and morphology of the mass in question, in conjunction with clinical features such as patient age, gender, signs, symptoms, and laboratory values, can usually lead to a short list of possible etiologies, thereby directing appropriate additional diagnostic procedures or therapeutic approaches.
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PMID:Imaging of anterior mediastinal masses. 1792 Oct 91

"Vitreous silica" is a particular form of amorphous silica, much neglected in experimental studies on silica toxicity. In spite of the incorrect term "quartz glass", often employed, this material is fully amorphous. When reduced in powdered form by grinding, the particulate appears most close to workplace quartz dust but, opposite to quartz, is not crystalline. As silicosis and lung cancer are also found among workers exposed to "quartz glass", the question arises of whether crystallinity is the prerequisite feature that makes a silica dust toxic. We compare here the behavior of comminuted quartz, vitreous silica, and monodispersed silica spheres, as it concerns surface reactivity and cellular responses involved in the accepted mechanisms of silica toxicity. Care was taken to choose samples of extreme purity, to avoid any effect due to trace contaminants. Quartz and vitreous silica, opposite to silica spheres, show irregular particles with sharp edges, stable surface radicals, and sustained release of HO(*) radicals via a Fenton-like mechanism. The evolution of the heat of adsorption of water as a function of coverage shows with quartz and vitreous silica a similar pattern of strong hydrophilic sites, nearly absent on the other silica specimen. When tested on a macrophage cell line (MH-S), vitreous silica and pure quartz, but not the monodispersed silica spheres, showed a remarkable potency in cytotoxicity, nitric oxide synthase activation and release of nitrite, and tumor necrosis factor-alpha production, suggesting a common behavior in inducing an oxidative stress. All of the above features appear to indicate that crystallinity might not be a necessary prerequisite to make a silica particle toxic.
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PMID:Does vitreous silica contradict the toxicity of the crystalline silica paradigm? 2008 95


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