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PubMed1978

TruCutR needle biopsy in asbestosis and silicosis: correlation of histological changes with radiographic changes and pulmonary function in 41 patients.

A percutaneous needle biopsy was performed with a TruCut needle on 41 patients with suspected pneumoconiosis. Patients selected for biopsy tended to have brief or unusual dust exposure, as well as questionable radiographic opacities. Sixteen had been exposed to asbestos, 13 to silica and 12 to mixed dust containing quartz, coal, iron, asbestos and talc. All patients in the asbestos group and most in the other two groups had a reduced transfer factor. Most patients in the asbestos group and about 25% of the other patients had restrictive ventilatory impairment. Chest radiographs were assessed according to standard films of the ILO U/C International Classification (International Labour Office, 1972). In 25 patients radiographic opacities were absent or acanty (categories 0--1/1). The dominant radiographic feature of many patients exposed to asbestos was a ground-glass appearance or a bilateral elevation of the diaphragm, or both, features difficult to assess according to the ILO U/C scheme. Most histological changes were those usually seen in pneumoconiosis. However, in only two patients with silicosis were silicotic nodules detected. The specimens of seven patients showed a granulomatous inflammation. The severity of alveolar wall involvement correlated well with the transfer factor value but poorly with radiographic changes. The profusion of radiographic opacities also correlated poorly with functional impairment. As a diagnostic tool the needle biopsy was valuable in asbestosis and slightly less so in mixed-dust fibrosis. The biopsy specimens showed changes compatible with asbestosis in 75% of the suspected cases and in 86% of those in which asbestosis was the final diagnosis. In the mixed-dust group pneumoconiosis was confirmed in 67% and 80%, respectively. In the diagnosis of silicosis an open biopsy is probably more reliable than a percutaneous one, particularly if radiographic changes are minimal. Histological changes in the needle biopsy specimen were compatible with silicosis in only 36% of the suspected cases and in 63% of those in which the final diagnosis was silicosis.

Adult↗
PubMed1990

Silica exposure, silicosis, and lung cancer: a necropsy study.

Recent studies of the association between lung cancer and silicosis and silica dust have been inconclusive; some showing positive association and some showing none. The present study matched 231 cases of lung cancer with 318 controls by year of birth. Subjects were selected from the necropsy records of the National Centre for Occupational Health. Data on intensity and duration of exposure to silica dust were obtained from personnel records. Presence or absence of lung cancer and the presence and severity of silicosis of the parenchyma, pleura, and hilar glands were documented from necropsy reports. Smoking data were abstracted from records of routine examinations. No case-control differences were noted for any of the exposure indicators including cumulative dust exposure, total dusty shifts, weighted average intensity of exposure, total underground shifts, and shifts in high dust. Similarly, no association was found between lung cancer and the presence or severity of silicosis and any site. Stratified analyses showed neither significant nor suggestive trends when case-control comparisons for silicosis were examined by level of dust exposure or smoking. Reasons for disparity between these results and those of some other studies may include concomitant exposures to radon daughters, asbestos, diesel emissions, and cigarette smoking; idiosyncracies of the compensation process; and the possibility of a threshold in the relation(s).

Aged↗
PubMed1991

The relation between fibrosis of hilar lymph glands and the development of parenchymal silicosis.

The necropsy findings on the cardiorespiratory organs of 849 South African gold miners were analysed to test the hypothesis that fibrosis of the hilar lymph glands predisposes to the development of parenchymal silicotic nodules. Four hundred and eighty three cases had fibrosed glands, 34% of which also had parenchymal silicosis. By comparison, of 238 cases with silicosis, 88% had fibrosed glands. The proportion of cases with both silicosis and fibrosed glands, as well as those with gland fibrosis only, increased with increasing duration of exposure. As far as can be ascertained from a necropsy series such as this, it is possible that fibrosis of the lymph glands may predispose to the development of lung parenchymal silicosis.

Fibrosis↗
PubMed1992

Relation between exposure to respirable silica dust and silicosis in a tungsten mine in China.

To estimate the quantitative relation between exposure to respirable silica dust and risk of an attack of silicosis, 1151 workers exposed to silica dust and employed from 1958 to 1987 in a tungsten mine in China were investigated. The results showed that the ratio of respirable silica dust concentration to total silica dust concentration was 0.529. Then, the total silica dust concentration in historical surveillance and monitoring data was converted to respirable silica dust concentration. The free silica content in respirable dust determined by x ray diffraction averaged 24.7%. Multiple logistic regression was used for the dichotomous dependent variables (presence or absence of silicosis). The independent variables in the multiple logistic regression with presence of silicosis as the dependent variable were age when first exposed, tuberculosis (presence or absence), and cumulative exposure to respirable silica dust. The partial regression coefficient of individual cumulative exposure was estimated as 0.079. It implied a positive association between exposure to respirable silica dust and risk of an attack of silicosis. The exposure limit for respirable silica dust was estimated as 0.24 mg/m3 under given conditions.

Dust↗
PubMed1995

Further information on aluminium inhalation in silicosis.

OBJECTIVES: In previous studies, a significant reduction in biological activity of quartz by the surface chemistry of aluminium was noted. Aluminium lactate inhalation one month after quartz exposure significantly suppressed silicosis. In a recent study, it was noted that aluminium inhalation failed to alter the silicosis process after disease was recognised by standard chest radiography in the first year after monthly treatment. METHODS: That study was extended with the same groups of sheep, the aluminium treated group received weekly aerosol of 100 mg of aluminium lactate for an additional two years. All sheep were evaluated at three-month intervals by chest radiography, lung function, and lung lavage. RESULTS: The sheep with silicosis had significantly reduced lung functions, increased cellularity, phospholipids, and hyaluronan. These changes persisted for several years without significant differences between the silicotic sheep with or without the aluminium aerosol treatment. CONCLUSION: Aluminium aerosol treatment of silicosis after radiographic recognition of disease and the end of exposure did not alter the disease process.

Administration, Inhalation↗
PubMed1975

Silicosis among grindstone cutters in the north of Nigeria.

Many of the grindstones used in Nigerian homes are quarried from sandstone in a small group of villages near Kano in the extreme north of the country. Of an unselected group of 126 stonecutters from two of these villages 49 were found to have radiographic evidence of silicosis, with progressive massive fibrosis in 17. Those with silicosis had worked longer in the quarries than 77 whose radiographs showed no evidence of silicosis. Sixty-three per cent of the silicotics had respiratory symptoms, the commonest being breathlessness on moderate exertion. Cough was the earliest symptom in 42%. Only 35% had abnormal physical signs in the cardiorespiratory system, 18% had clearly reduced ventilatory capacity, and airways obstruction was evident in 16%. The prevalence of silicosis in these open-cast sandstone quarriers is unexpectedly high. This is probably explained by the intensity of exposure and the particular kind of sandstone being worked. Reduction of dust exposure in these quarries raises severe practical problems, but the inhabitants of this drought-ridden area can scarcely be expected to abandon their traditional livelihood.

Adolescent↗
PubMed1986

Relationship between silicosis and rheumatoid arthritis.

The relationship between rheumatoid arthritis and silicosis was studied by means of a case-control study in South African gold miners. One hundred and fifty seven miners with rheumatoid arthritis classified as "definite" (91) or "probable" (66) were individually matched by year of birth with miners who had no evidence of rheumatoid arthritis. Unmatched analysis of the case-control status for "probable" and "definite" cases yielded an odds ratio of 2.84 (p = 0.0001). Separate analyses yielded an odds ratio of 3.79 (p = 0.0006) for "definite" cases, a non-significant odds ratio for "probable" cases, and an odds ratio of 5.00 (p = 0.0003) for the presence of rheumatoid factor. These results could not be explained on the basis of cumulative dust exposure or intensity of exposure. The rate of progression of silicosis in both the "definite" and the "probable" groups was greater than for the control patients with silicosis, as was the probability of silicosis presenting at the start with larger nodules (type r).

Arthritis, Rheumatoid↗
PubMed1978

The radiographic findings in acute silicosis.

The radiological features of 4 cases of acute silicosis in sandblasters are described and correlated with the pathological findings. Alveolar involvement was more extensive than in chronic silicosis; in 2 cases an alveolar exudate similar to that found in alveolar proteinosis was present. The radiological changes in acute silicosis differ substantially from those in classical silicosis, mainly on the basis of the differing alveolar response.

Acute Disease↗
PubMed2000

Bullous pemphigoid associated with silicosis.

Bullous pemphigoid (BP) has never before been reported to associate with silicosis, although there are numerous reports of silicosis accompanied by different autoimmune diseases, such as systemic sclerosis, systemic lupus erythematosus, dermatomyositis or rheumatoid arthritis. We report on a 63-year-old Japanese patient with silicosis who developed tensed bullae, erosions and macular pigmentation on the trunk and extremities. Indirect immunofluorescence revealed anti-basement-membrane-zone antibodies; immunoblotting analysis demonstrated that the patient's serum reacted with the 230-kD BP antigen in the epidermal extracts, as well as a recombinant protein of the NC16a domain of 180-kD BP antigen. Clinical symptoms improved after treatment with systemic steroids. To the best of our knowledge, this is the first reported case of BP associated with silicosis.

Humans↗
PubMed1995

Increased susceptibility to silicosis and TNF-alpha production in C57BL/6J mice.

Toxic oxygen species and several proinflammatory cytokines are involved in the pathogenesis of silicosis. In order to understand whether factors that lead to susceptibility to ozone are also important in silicosis or not, we examined ozone-sensitive C57BL/6J mice and ozone-resistant C3H/HeJ mice as models of silicosis. We also analyzed the production of proinflammatory cytokines in both the acute and the chronic phases. On Day 2 after silica injection, the ozone-resistant C3H/HeJ mice showed significantly higher cellular responses as recognized by bronchoalveolar lavage (BAL) cell counts than did the C57BL/6J mice. In the chronic phase (Day 28 after silica injection), the ozone-sensitive C57BL/6J mice showed significantly greater responses to instilled silica judged by total protein and cell number in BAL fluid, hydroxyproline content, and histology than the ozone-resistant C3H/HeJ mice. TNF-alpha production by BAL cells after silica exposure was significantly higher in C57BL/6J mice than in C3H/HeJ mice in the chronic phase, whereas there was no significant difference in IL-1 alpha production between both strains of silica-injected mice. Also, the control C57BL/6J mice had significantly higher secretions of TNF-alpha than did the control C3H/HeJ mice in the acute phase. These results suggest that ozone-sensitive C57BL/6J mice are also more susceptible to silicosis than are ozone-resistant C3H/HeJ mice, and that the initial lower cellular responses and increase in TNF-alpha production may be related to the higher level of inflammatory and fibrotic response in the C57BL/6J mice.

Animals↗
PubMed1981

Silicosis in silica flour workers.

In July 1979, the health of 86 current and ex-workers at 2 silica mining and milling operations in southern Illinois was examined using a respiratory questionnaire, spirometry, and chest radiographs. None of 25 current workers with less than 1 yr of exposure to silica dust had radiographic evidence of silicosis. For 61 current workers and ex-workers with 1 or more yr of exposure, chest radiographs showed 16 (26%) with simple silicosis and 7 (11%) with progressive massive fibrosis. Of these 23, 8 with simple silicosis and 3 with progressive massive fibrosis began work after the first Mine Safety and Health Administration inspection in 1973. These data and a review of federal dust inspection results between 1973 and 1979 showed that these cases of silicosis could have been prevented by effecting compliance with the existing dust standard.

Adult↗
PubMed2000

Interferon-gamma production by specific lung lymphocyte phenotypes in silicosis in mice.

We recently described overproduction of interferon (IFN)-gamma by lung lymphocytes in mice with silicosis (11% of cells in air-control versus 19% of cells from silica-exposed mice; Davis and colleagues, Am. J. Respir. Cell Mol. Biol. 1999;20:813-824). We hypothesized that the increased IFN-gamma production might be due to selective enrichment of one lymphocyte phenotype. To test this hypothesis, small mononuclear cells from lung digest preparations of mice exposed 4 mo previously to cristobalite silica (70 mg/m(3), 12 d, 5 h/d) or to sham-air were stained for intracellular cytokines and surface antigen phenotypes, and examined by flow cytometry. Air-sham mouse lung digests included CD4(+) (16%) and CD8(+) (6%) T cells, gammadelta T-cell antigen receptor (TCR)(+) CD4(-)CD8(-) T cells (3%), natural killer (NK) cells (15%), B cells (6%), and macrophages (12%). The total number of lung lymphocytes was increased 1.7-fold in silicosis, but the phenotype frequencies did not change significantly. In the control lungs IFN-gamma was produced by three major phenotypes of lymphocytes: 5% of CD4(+) T cells, 5% of gammadelta-TCR(+) CD4(-)CD8(-) T cells, and 2% of NK cells. The percentage of each type producing IFN-gamma was increased 2- to 3-fold in silicosis. When multiplied by cell number, the increased percentages yielded a 3- to 5-fold increase in the total number of each IFN- gamma-producing phenotype in the lung. Our results demonstrate no selective phenotype enrichment but upregulated IFN-gamma production by at least three lymphocyte phenotypes. IFN-gamma may be an important signal driving lymphocyte differentiation and macrophage activation in silicosis.

Animals↗
PubMedDate not supplied

Silicosis and tuberculosis in Zambian miners.

Silicosis and tuberculosis (TB) are significant mining-related illnesses in developing countries. The purpose of this study was to examine annual cases of these diseases in Zambian miners, including comparison of periods before (1960-1970) and after (1992-2002) the arrival of the HIV/AIDS pandemic. The Occupational Health and Safety Research Bureau of Zambia reported 2114 cases from 1945 to 2002. Of these, 22.7% were silicosis, 65.4% TB, and the remaining 11.9% silicotuberculosis. While silicosis cases decreased from 28.6% to 12.4% with the arrival of HIV/AIDS, there was a large increase in tuberculosis cases (37.1% to 86.1%), with a corresponding decrease in silicotuberculosis cases (34.3% to 1.6%). Although silicosis remains an occupational health issue in Zambian miners, the most significant problem appears to be the marked increase in cases of TB.

Adult↗
PubMedDate not supplied

Recent trends of age-specific pneumoconiosis mortality rates in the United States, 1985-1996: coal workers' pneumoconiosis, asbestosis, and silicosis.

The authors examined the temporal trends of age-specific pneumoconiosis mortality from coal worker's pneumoconiosis (CWP), asbestosis, and silicosis in the United States in 1985-1996. Mortality data were derived from the National Center for Health Statistics multiple causes of death files for the period. Age-specific mortality rates were computed for three age groups (15-44, 45-64, and > or = 65 years) among decedents with mention of CWP, asbestosis, or silicosis. Linear regression analysis was performed to examine the annual changes in age-specific mortality rates, by age group, with each specific condition. The CWP mortality rates declined significantly (p = 0.0001) in the groups 45 years old and older, but not in the age group 15-44. Asbestosis mortality rates declined significantly (p = 0.005) for the age group 45-64, while increasing (p = 0.0001) for those aged 65 years and older. However, in the younger age group 15-44, the rates showed no significant trend. Silicosis mortality rates declined significantly (p = 0.0001) for all groups. The continued occurrence of deaths from CWP, asbestosis, and silicosis among young adults may be the result of high levels of exposure to occupational risks. These results suggest that pneumoconiosis surveillance may help to evaluate the temporal pneumoconiosis mortality patterns in the United States.

Adolescent↗
PubMed2003

Evaluation of percutaneous endoscopic gastrostomy in elderly patients with silicosis and co-morbidities.

To clarify the indications and usefulness of Percutaneous endoscopic gastrostomy (PEG) in patients with Silicosis and some co-morbidities, we analyzed eight cases of silicosis, who suffered from dysphagia and had received a PEG for tube feeding during the period from 1998 to 2002. The characteristics, and clinical course, of each case were statistically analyzed before and during PEG usage. All cases were bed-ridden males, with a mean age of 80 years. The profusion rate (PR) grade of silicosis was for five cases in category 2, and for three cases in category 4. Most of the co-morbidities were dementia (five cases), and chronic heart failure (four cases). There were no significant improvements in the measured nutrition criteria (albumin, lymphocytes) nor in respiratory function (arterial O2) between before and during PEG usage. Tube feeding through the PEG was not performed in three cases because of repeated aspiration pneumonia. The mean duration of PEG usage was 9 months, ranging from 5 to 20 months. Five cases died of the co-morbidities. Furthermore, there was significant deterioration in the bacteriological data (p = 0.001), suggesting a worsening of the swallowing disturbances during PEG usage, or the emergence of more resistant organisms as a result of empirical antibiotic therapy. The present results suggest that the indications of PEG in cases of severe chronic obstructive pulmonary disease (COPD) such as silicosis, associated with other morbidities, and with dysphagia, are somewhat limited. The patient's general condition should be an important factor in deciding whether or not this technique should be used.

Aged↗
PubMed1989

Quartz exposure, retention, and early silicosis in sheep.

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.

Animals↗
PubMed1987

Angiotensin converting enzyme in sarcoidosis and in silicosis.

Angiotensin converting enzyme (ACE) activities of bronchoalveolar lavage fluid (BALF) and serum in patients with sarcoidosis and with silicosis were measured. Serum ACE was measured by enzymic assay and radioimmunoassay. There was a close relationship between ACE activity and content (r = 0.78). Serum ACE activities in patients with active sarcoidosis (37.5 +/- 11.1 nmol/min/ml, mean +/- SD) and with silicosis (25.5 +/- 9.3) were significantly elevated from the control (18.6 +/- 6.0). BALF ACE activities in the control, patients with active sarcoidosis and with silicosis were 0.23 +/- 0.19 nmol/min/ml, 0.94 +/- 0.97 and 0.38 +/- 0.05, respectively. BALF ACE in patients with active sarcoidosis and with silicosis were significantly different from the control. When BALF ACE was corrected by the cell count of alveolar macrophage (per 10(6) cells), activity was significantly different from control only in the patients with sarcoidosis. Moreover, only the alveolar macrophages in sarcoidosis were stained by immunofluorescence and immunocytochemistry using rabbit antihuman ACE antibody. Induction of ACE in alveolar macrophage might have an important role for the activity or progression of sarcoidosis.

Adult↗
PubMed1992

Prediction of silicosis and lung cancer in the Australian labor force exposed to silica.

Empirical models for risk, based on recently published epidemiologic data, and simple prediction formulas were used to predict the occurrence of silicosis and lung cancer in the Australian labor force currently exposed to crystalline silica dust. As a result of an 0.9 (range 0.4-1.9)% average lifetime risk, approximately 1010 (range 380-2410) silicosis cases were predicted for the next 40 years among the estimated 136,400 men exposed at current silica dust levels [0.01-0.8 (average 0.094) mg.m-3]. Approximately 630 extra lung cancer cases (95% confidence interval 120-1320) would appear with an average excess risk of 0.5 (interval 0.1-1.1)%, the proportion of silica-induced lung cancer cases being about 15%. Currently 77% of the at-risk labor force is exposed to silica dust levels of < or = 0.1 mg.m-3. With this level as the limit, about 440 (range 140-1210) silicosis cases and 410 (interval 90-780) extra lung cancer cases would occur in 40 years. Adopting this level as the national exposure standard would reduce the risk of silicosis cases by 52% and the excess risk of lung cancer by 36%.

Adult↗