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PubMed1994

[Angiotensin-converting enzyme (ACE) in sarcoidosis, tuberculosis, silicosis, and coal mining workers].

We studied the seric activity of the angiotensin converting enzyme (ACE) in 19 patients with sarcoidosis, 14 tuberculosis, 16 silicosis and 15 workers of coal mining without silicosis and other concomitant diseases, in order to assess its usefulness as orientative parameter for the differential diagnosis of these processes. We found significantly increased values with respect to the control group in all of them: control group (40.84 +/- 13.06 U/l), sarcoidosis (57.77 +/- 16.47 U/l), tuberculosis (46.85 +/- 10.25 U/l), silicosis (61.50 +/- 21.40 U/l), miners (71.50 +/- 12.48 U/l). We did not detect any statistically significant differences between the several diagnostic groups except for miners and tuberculosis (p = 0.04). We conclude that this parameter is hot very useful for the diagnostic orientation of these processes.

Adult↗
PubMed1995

Silicosis surveillance in Ontario from 1979 to 1992.

This paper reports the detection rates of silicosis among silica-exposed persons first exposed to dust in 1950 or later and still employed in 1979 or later in the province of Ontario. The rate varied strongly with latency, being less than two new cases per 10 000 examinations during the first two decades from first exposure, reaching two new cases per 1000 examinations at 27 years from first exposure, and averaging between two and four new cases per 1000 examinations thereafter. A Poisson regression analysis found that the silicosis rate in the interval after 30 years from first exposure was more than 16 times higher than the rate prior to 20 years from first exposure. There was no significant difference in the diagnosis rates among the workers in the mining, primary metal, and nonmetallic mineral industries sectors. The rate of silicosis was higher among smokers than among never smokers (rate ratio 1.54).

Confidence Intervals↗
PubMed1995

Silicosis and lung cancer among workers in North Carolina dusty trades.

In 1940-1983, 760 cases of silicosis were identified among male North Carolina (NC) workers in dusty trades. Vital status was ascertained through 1983 for 714 silicotics, and death certificates were obtained for 546 of the 550 decedents. The standardized mortality ratio (SMR) for lung cancer based on United States rates was 2.6 [95% confidence interval (95% CI) 1.8-3.6] for whites, 2.3 (95% CI 1.5-3.4) for whites unexposed to other known occupational carcinogens, and 2.4 (95% CI 1.5-3.6) for whites with no other exposure and diagnosed with silicosis while still employed in dusty trades. In addition, the age- and smoking-adjusted rate for silicotics was 3.9 times higher (95% CI 2.4-6.4) than that of nonsilicotic metal miners. This analysis effectively controlled for confounding by age, cigarette smoking, exposure to other occupational carcinogens, and detection bias. The results congrue with the hypothesis of an association between silicosis and lung cancer.

Confidence Intervals↗
PubMed1995

Potential years of life lost and work tenure lost when silicosis is compared with other pneumoconioses.

Potential years of life lost (PYLL) and potential years of work lost (PYWL) because of pneumoconiosis were studied using the data from the Nationwide Epidemiological Study on Pneumoconioses in China. The cases were patients diagnosed with pneumoconiosis between 1949 and 1986. The subjects studied for PYLL included 74 741 cases ranging in age from 15 to 75 years, while for PYWL there were 74 224 cases with 1 to 35 years of remaining employment experience. Overall there were 1 489 692 potential years of life lost, and there was an average of 19.9 years for all pneumoconioses. Silicosis had the greatest mean PYLL with an average of 22.1 years. Coal workers' pneumoconiosis was the second leading cause of PYLL with an average of 17.0 years. The mean PYWL for all pneumoconioses was 19.7 years, and the mean PYWL from silicosis was 21.5 years. The conclusion was reached that silicosis is the most serious pneumoconiosis in China with regard to years of life lost, and chronic respiratory diseases such as chronic pulmonary disease and tuberculosis are the main causes of death for patients with pneumoconiosis.

Adolescent↗
PubMedDate not supplied

Comparison of inter-observer reproducibility between conventional chest radiography and AMBER in the evaluation of silicosis.

The aims of this study were to test inter-observer and intraobserver agreement in the diagnosis of silicosis using conventional chest radiography and AMBER. One hundred and fifteen patients underwent chest x-rays and AMBER for the diagnosis of silicosis. Five readers blindly and independently evaluated the radiograms with standard ILO/UC classification scales. Reproducibility was assessed using ANOVA repeated measurements methods. AMBER showed a better technical quality of radiograms than conventional chest x-rays; interobserver reproducibility was high and similar (R = 0.75); intraobserver agreement between chest x-rays and AMBER was high ranging from 0.62 to 0.86 for the 5 readers. Notwithstanding the absence of standards for profusion classification, the interobserver reproducibility with AMBER was similar to that obtained with chest x-rays. Moreover, the intraobserver agreement in profusion scoring between AMBER and chest radiography was high, suggesting that AMBER and chest radiography provided similar information in the evaluation of silicosis.

Aged↗
PubMed1996

[The analysis of peripheral blood lymphocytes of patients with silicosis and effects of silica in vitro].

It is well known that patients with silicosis are frequently associated with hyperglobulinemia, RA or PSS. It is also suggested that silica can drive and activated the immune system. In this study, we intended to measure the percentage of CD4+CD45RA+ cells in the peripheral blood of patients with silicosis and to investigate whether silica can actually activate human lymphocytes in vitro or not. Peripheral blood from 45 patients with silicosis was stained with OKT4 and 2H4 monoclonal antibodies, and measured by FACS analysis at 1st day and also checked similarly after 6 days-incubation without patients' sera. The intracellular Ca++ level was also checked after incubation with the normal human lymphocytes with silica by FACS analysis, using Fluo3-AM. CD4+CD45RA+ T cells decreased significantly in number. One to 5 minutes after the incubation with silica, intracellular Ca++ level increased markedly, which means the activation of lymphocytes in vitro. These results revealed that silica can activate human lymphocytes in vitro, but the role in vivo remains to be clarified.

Aged↗
PubMedDate not supplied

Antineutrophil cytoplasm antibodies in patients with silicosis.

The presence of antineutrophil cytoplasm antibodies (ANCA) was followed up in silicosis with or without renal involvement. From the 68 patients with silicosis, 5 presented renal involvement. Of these 3 showed the presence of pANCA. The other 63 patients without renal involvement presented cANCA only in 2 cases. The control group showed no presence of ANCA. The incidence of ANCA in silicosis with renal involvement was discussed in view of an eventual elucidation of the pathogenesis of this disease, which was frequently associated with autoimmunity diseases.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1997

Effect of beclomethasone dipropionate inhalation on eosinophilic bronchitis in patients with silicosis.

The efficacy of beclomethasone dipropionate (CAS 5534-09-8, BDP, beclomethasone) inhalation therapy over the course of 12 months were evaluated in 42 patients with established chronic silicosis. Their pulmonary functions were monitored every 3 months and volume of sputum production was established daily. Subjects were divided randomly into two groups; 21 patients (BDP group) were treated with BDP (400 micrograms/day) by way of a metered-dose inhaler, while the 21 controls did not receive the BDP inhalation therapy. Although FVC (forced vital capacity), FEV1 (forced expiratory volume in 1 s), MMEF (maximal mean expiratory flow) and arterial blood oxygen tension did not improve significantly, sputum production significantly decreased in the BDP group. The patients who responded most dramatically to the treatment presented with sputum eosinophilia and elevated serum IgE levels prior to therapy. Pulmonary tuberculosis or exacerbation of chronic airway infection was not observed in any of the patients. These results suggest that corticosteroid inhalation therapy is helpful in the management of chronic silicosis, especially in patients with sputum eosinophilia. Positive atopic factors may be related to the pathogenesis of eosinophilic bronchitis, a complication of chronic silicosis.

Aged↗
PubMed1998

Silicosis in mice: effects of dose, time, and genetic strain.

Experimental silicosis allows study of the mechanisms of lung injury, inflammation, and fibrosis. Inbred mice are an attractive species in which to study these mechanisms because of recent progress in murine immunology, molecular biology, and genetics. We exposed mice to an aerosol of silica and examined the effects of exposure dose, the evolution of disease features over time, and the variation in responses among four inbred strains. In C3H/HeN mice incremental cumulative exposure doses of cristobalite silica caused increased initial lung dust burden 12 to 16 weeks post-exposure, progressively intense pathological responses, and increased total lung collagen (hydroxyproline). The histopathological changes and total lung collagen increased progressively over time after exposure. We compared the features of silicosis in four strains of inbred mice selected for common use or immunologic reactivity 16 weeks after aerosol inhalation exposure to crystalline cristobalite silica (70 mg/m3, 5 hours/day, 12 days). C3H/HeN mice demonstrated histopathological silicotic lesions and enlarged intrapulmonary lymphoid tissue, and increased lung wet weight, bronchoalveolar lavage (BAL) recovery of macrophages, lymphocytes, and neutrophils, and total lung collagen (hydroxyproline). BALB/c mice developed slight pulmonary lesions; MRL/MpJ mice demonstrated prominent pulmonary infiltrates with lymphocytes; New Zealand Black mice developed extensive alveolar proteinaceous deposits, inflammation, and fibrosis. Our findings demonstrate orderly dose-time-response relationships, and a substantial variation of responses among inbred strains of mice. This model should prove valuable for future experimental interventions into the mechanisms of silicosis.

Administration, Inhalation↗
PubMed1998

Persistent overexpression of interleukin-1beta and tumor necrosis factor-alpha in murine silicosis.

The cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNFalpha), derived from macrophages and other cells, may promote mononuclear cell inflammation and fibrosis in pulmonary silicosis. C3H/HeN mice were exposed to control air or to an aerosol of 70 mg/m3 cristobalite silica for 5 h/d for 12 days and examined at 2 and 16 weeks after exposure. This exposure resulted in murine silicosis, as manifested by focal mononuclear cell accumulations, diffuse interstitial fibrosis, lymphoid tissue enlargement, recruitment of inflammatory cells into BAL fluid, and increased total lung collagen. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) with designed primers and membrane hybridization with biotinylated cDNA probes were used to assess the abundance of IL-1beta and TNFalpha mRNA. In situ hybridization with digoxigenin-labeled cDNA probes was used to localize gene expression. Persistent overexpression of both IL-1beta and TNFalpha were found at 2 and 16 weeks in the lungs of silica-exposed mice compared with air-sham control mice. IL-1beta and TNFalpha expression localized to individual mononuclear cells in the alveolar spaces, groups of cells within the aggregate lesions, and scattered mononuclear cells in BALT and lymphoid nodules. Thus, cells producing IL-1beta and TNFalpha appear to be intimately associated with the evolving lesions of silicosis, and the lymphoid tissue of the lung may be important in driving the pathogenesis of this disease.

Animals↗
PubMedDate not supplied

Relationship between serum total sialic acid and C-reactive protein in silicosis.

Serum total sialic acid and C-reactive protein (CRP) were studied in 68 patients with silicosis divided into 3 groups according to the evolutive stage of disease. The results were compared with the data obtained in a control group of 35 healthy subjects. The changes in serum total sialic acid levels were in parallel with those of CRP in silicosis. Patients in stage III had the highest mean values of serum total sialic acid (p < 0.01) and of CRP (p < 0.001). Linear regression analysis revealed a close positive correlation between serum total sialic acid and CRP levels in silicosis (r = 0.86, p < 0.01).

Adult↗
PubMed1976

[Experiences with the mediastinoscopy for the diagnostics of silicosis (author's transl)].

122 patients, suspicious for silicoses, with a history of silicogen dust exposure, radiological changes and restricted lung function values were examined by mediastinal biopsy for securing the diagnosis. In 82 patients (67,2%) a silicosis could be confirmed by histological examinations of the mediastinal lymph nodes. A close association between silicosis in the lungs and in the lymph nodes is empirically suggested. If the histological findings were in compliance with suspicious radiological changes and patients history, silicosis was acknowledged as an occupational disease. In patients with beginning silicotic changes in the peripheral two upper lung fields associated with an hilar hyperplasia, a higher proportion of positive results could be found. The most positive alterations were found in the lymph nodes of the right hilus. The mediastinoscopical findings in other parts proved not to be so yielding. Therefore, in cases with anatomical difficulties the surgical examination should not be extended to other parts.

Adolescent↗
PubMed1976

[Preventive chemotherapy in persons with silicosis and silicotuberculosis (author's transl)].

In some countries extensive research is carried out on preventing tuberculous disease by administration of INH. In GDR since about 1960 chemopreventive measures were taken in cases of silicosis and silicotuberculosis too. More than 2000 patients of the Magdeburg Pneumoconiosis Center were followed-up from 1960 to 1969. The high risk of tuberculous disease of 21% in the group of silicosis patients without administration of INH could be reduced to 14% after preventive administration of INH. However, such clear effects were observed only under optimal conditions, that is sufficient dosage, duration and reliability of treatment. On the base of these results and other publications patients with silicosis with and without tuberculous residues should be included into the programmes of preventive chemotherapy of the chest clinics.

Aged↗
PubMed1998

[The influence of superoxide dismutase and catalase on the course of the pathological process in the lungs in experimental silicosis].

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.

Animals↗
PubMed1976

A diffuse form of pulmonary silicosis in foundry workers.

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.

Humans↗
PubMed1996

Short course chemoprophylaxis with rifampicin, isoniazid and pyrazinamide for tuberculosis evaluated in gold miners with chronic silicosis: a double-blind placebo controlled trial.

SETTING: A medical facility for approximately 90,000 gold miners employed on 24 South African gold mines. OBJECTIVE: To evaluate the effectiveness of rifampicin, isoniazid and pyrazinamide given for 3 months for the prevention of tuberculosis in men with silicosis. DESIGN: A randomised double-blind placebo controlled trial with active 4-year follow up of subjects by routine radiographic screening. RESULTS: A total of 382 gold miners with silicosis were randomised to receive rifampicin 600 mg, isoniazid 400 mg and pyrazinamide 1.25 g daily as Rifater or a placebo. These men have been followed for 4 years since the end of the treatment period. Eleven men who received the combination tablet and 15 men who received the placebo tablet have developed tuberculosis (chi 2 df1 = 0.66, P = 0.4). CONCLUSION: This multi-drug short course chemoprophylaxis regimen has failed to prevent tuberculosis in miners with silicosis. Even if a larger study had demonstrated a statistically significant effect of the regimen as compared with placebo, the rate of tuberculosis in the men who received the three-drug regimen was unacceptably high.

Adult↗
PubMed1991

[Does the average dust concentration modify the critical dust dose leading to silicosis?].

This article is based on the established fact that there is a relationship between the probability of the occurrence of silicosis and the inhaled amount of dust, the latter being represented by the concept of "dust dose" which is a product of dust concentration multiplied by the period of exposure. On investigating the "dust dose" values in 179 former coal miners in the East German town of Zwickau, however, we found that the "dust dose" principle does not apply to low to medium dust concentrations. We can now outline our idea of the origin and development of silicosis as follows: Below an initial threshold value of the "dust dose" it is improbable that silicosis will develop. Beyond that value, i.e. at medium dust concentrations, the time that elapses between the beginning of exposure and the onset of the disease is constant, namely, 20 years. However, the "dust dose" values that trigger the disease vary greatly. For dust concentrations beyond a second threshold value matters are as originally expected: the dust dose being constant, the disease will set in the earlier, the higher the dust concentration. To visualize these effects, a smoothing mathematical evaluation method was combined with a variant of the t test.

Adult↗
PubMed1997

Cancer incidence and mortality among Finnish asbestos sprayers and in asbestosis and silicosis patients.

Cohorts of Finnish asbestos sprayers and of asbestosis and silicosis patients were followed for cancer with the aid of the Finnish Cancer Registry in the period 1967-1994. Compared with the cancer incidence of the total Finnish population, asbestos sprayers had an increased risk for total cancer (standardized incidence ratio [SIR] 6.7, 95% confidence interval [95% CI] 4.2-10); lung cancer (SIR 17.95% CI 8.2-31); and mesothelioma (SIR 263, 95% CI 85-614). The SIR of the asbestosis patients was 3.7 (95% CI 2.8-5.0) for all sites, 10 (95% CI 6.9-14) for lung cancer, and 65 (95% CI 13-188) for mesothelioma. The silicosis patients also had significantly high SIR values for all sites (1.5, 95% CI 1.0-2.1) and lung cancer (2.7, 95% CI 1.5-4.5). The values for the SIR and the standardized mortality ratio for all sites and lung cancer were very similar, and therefore it seems that both are reliable indicators of the occurrence of occupational cancer. It was concluded that pneumoconioses patients and asbestos-exposed workers have a markedly elevated risk for cancer. Asbestos-induced occupational cancers are not only diseases of the elderly, since the relative risk is high also for middle-aged people.

Adult↗