Magnetometric evaluation of the effects of gallium arsenide on the clearance and relaxation of iron particles.

Intratracheal instillation of GaAs suspension has been histopathologically shown to induce a diffuse pulmonary response. In the present study, magnetometry was used to evaluate the effects of intratracheally instilled GaAs on the behavior of externally magnetized iron particles instilled in rabbit lung. Magnetometric evaluation of the effects of GaAs in rabbits dosed with 30 mg or 300 mg/animal showed significant decreased relaxation of iron particles at 1, 3, 7, 14, 21 and 28 days following instillation compared with the controls. Relaxation indicates a rapid decrease of remanent magnetic field following magnetization of the lungs due to random rotation of phagocytized iron particles in macrophages. Clearance of the iron particles was measured by serial determinations of the remanent magnetic field at the end of magnetization estimated from relaxation curves. Clearance was significantly impaired in rabbits exposed to both doses of GaAs at 14, 21 and 28 days after instillation. Dose-effect relationships were observed in both cases. Histological examination of lungs instilled with these doses indicated active phagocytosis of GaAs and iron particles by alveolar macrophages.

Rounded atelectasis associated with silicosis.

Two cases of autopsy-proven, silicosis-associated rounded atelectasis (SARA) are reported. Clinicopathologically, SARA shows a combination of rounded atelectasis and the typical features of silicosis. Pathologically, SARA is characterised by the presence of numerous silicotic nodules deposited throughout the atelectatic lung tissue, which otherwise shows the ordinary features of rounded atelectasis. SARA may contribute to the development of massive fibrosis in silicotic lungs.

Triple lung cancers in a patient with silicosis.

A case of pulmonary silicosis associated with triple lung cancers is presented. Two of the three tumors were unexpected clinically. The discussion deals with the diagnostic difficulty in radiological differentiation between the pneumoconiotic mass lesion and superimposed tumor shadows, as well as the possible causal relationship between the two conditions. From the practical point of view, elderly patients with pneumoconiosis should be carefully monitored for the development of lung cancer.

Diffuse interstitial fibrosis in nonasbestos pneumoconiosis--a pathological study.

Pathological examinations of 233 consecutive autopsy cases with nonasbestos pneumonconiosis revealed evidence of diffuse interstitial fibrosis (DIF) in 64 (27.5%), among whom 45 (19.3%) showed bilateral involvement and 9 (3.9%) extensive disease closely resembling usual interstitial pneumonia. The patients with DIF were significantly older and had longer occupational histories as compared with those without DIF. There was no correlation between the occurrence of DIF and the type of the underlying disease (silicosis or mixed dust pneumoconiosis) except that an extensive DIF was more frequently associated with mixed dust pneumoconiosis. The extensive DIF developed an in situ malignancy much more frequently (33.3%) than the focal disease (2.6%).

Pulmonary alveolar proteinosis as a component of massive fibrosis in cases of chronic pneumoconiosis. An autopsy study of 79 cases.

Histopathological analysis of massive fibrosis (MF) in lungs obtained from 79 patients with chronic pneumoconiosis revealed evidence of pulmonary alveolar proteinosis (AP) in a surprisingly high proportion of the cases (73%), suggesting that AP may be a usual constituent of MF in chronic pneumoconiosis. AP is not a specific morphological counterpart responsible for acute silicosis. In order to explain the occurrence of AP in MF, several hypothetical mechanisms are proposed and discussed.

Silicosis, mixed dust pneumoconiosis, and lung cancer.

A total of 764 autopsy cases with a pathological diagnosis of nonasbestos pneumoconiosis were investigated in a search for lung cancer: 146 patients bore 148 lung cancers (19.1%). The incidence of a lung cancer was associated positively with aging longer occupational exposures, and smoking habits. A reverse correlation was found between carcinogenesis and the severity of pneumoconiosis. A statistically significant increase in the incidence of certain types of lung cancer (squamous cell carcinoma + small cell carcinoma) was found in silicotic lungs with massive fibrosis as compared to lungs with mixed dust pneumoconiosis of comparable severity. Although there appears to be no dose-response relationship in general between silicosis and lung cancer, it is advisable to consider the possibility that a presumptive silica-induced carcinogenesis might be masked by the severe fibrosis of a silicotic type, which obliterates the lung tissue in a different way from asbestosis, which is associated with epithelial proliferation.

Lung cancer risk among pneumoconiosis patients in Japan, with special reference to silicotics.

A cohort study was conducted on 3335 hospitalized male pneumoconiosis patients in order to determine their lung cancer mortality. The patients were collected from 11 hospitals specializing in the treatment of pneumoconiosis and other occupational diseases and injuries, and were followed up during 1979-1983. Age-adjusted expected numbers were calculated using the mortality of the general population as a standard. A significantly high O/E ratio (4.80) for lung cancer was observed, particularly among silicotics (6.03). A slightly more than two-fold increase in risk for lung cancer was found among those who had never smoked. No dose-response relationship was found between lung cancer mortality and duration of dusty work or radiographic categories. A nested case-control analysis showed work experience in the ceramics industry to be a risk factor for lung cancer.

Low serum alpha-1-antitrypsin level as a contributory factor of combined emphysema in silicosis.

In order to evaluate low serum alpha-1-antitrypsin level as a contributory factor of combined emphysema in silicotic patients, serum alpha-1-antitrypsin analysis was carried out in 80 patients with silicosis. Low serum alpha-1-antitrypsin level was found in 5 patients. Large opacities were observed roentgenologically in only 1 out of these 5 cases in contrast to 31 of the other 75 cases. Also the suggestive findings for the emphysema were showed in 4 of these 5 cases while such findings were found on their chest X-ray films in only 43 of the other 75 cases. FEV 1.0% below 50 were calculated in 3 of the 5 cases, on the contrary in 22 of the 75 cases. RV above 50% predicted value was showed by all the 5 low antitrypsin patients, in contrast to only 25 of other 74 cases. The silicotic patients with low serum alpha-1-antitrypsin concentration are most likely to have an association with a high incidence of complicated emphysema.

Evaluation of surgical treatments for the major lesion of bilateral silicotuberculosis.

The present communication deals with the follow-up study of 24 patients with bilateral silicotuberculosis in whom only unilateral operation was carried out for major lesions. The operative procedure consisted of pulmonary resection, thoracoplasty or combined operation such as cavernostomy, intracavitary filling of a pedunculated muscle flap and thoracoplasty. The follow-up period ranged 1 year to 12 years and 5 months. The results of surgical treatment for unilateral major lesions and their effect on the contralateral minor lesions were clinically assessed by alterations in the chest x-ray findings and tubercle bacilli in sputum. In 16 of 24 patients (67%) alleviation was obtained, whereas no change occurred in 3 (13%) and aggravation in 5 (21%). The surgical treatment for unilateral major lesion brought about 41% of improvement in the contralateral minor lesions. Contralateral minor lesions remained unchanged in 46% of patients and aggravated in 14%. This shows a value of the surgical threatment for bilateral silicotuberculosis. It should be emphasized that surgical treatments more aggressive than have been heretofore practiced can be employed.

Biomagnetism in Japan.

The study of biomagnetic fields originating in a biological body is called biomagnetism. Among various fields of biomagnetism, this paper reviews the research and clinical works in magnetocardiogram, neuromagnetism, magneto-oculogram, magnetopneumogram and magnetic measurement for cell motility carried out in Japan.

Radiologic and pathologic characteristics of mixed dust pneumoconiosis.

Modern radiologic technology has to led to increased diagnostic efficacy and accuracy in demonstrating pulmonary changes secondary to occupational dust exposure. This article presents three cases of typical and two cases of atypical silicosis with rounded atelectasis as seen in computed radiographic (CR), computed tomographic (CT), and scintigraphic images and autopsied lung specimens. Chest radiographs revealed both small rounded and small irregular opacities. Small irregular opacities on chest radiographs often proved to be reticular or honeycomb patterns on CT scans. Irregular opacities seen on CR and CT images represented interstitial fibrotic or mixed dust fibrotic changes associated with the accumulation of birefringent particles and emphysematous change, as noted at histologic analysis. CT scans and scintigrams were useful for visualizing parenchymal abnormalities, especially fibrotic change, emphysematous change, and pleural abnormalities.

Mixed dust fibrosis and tuberculosis in comparison with silicosis and macular pneumoconiosis.

BACKGROUND: To assess the relationship between mixed dust fibrosis (MDF) and tuberculosis. METHODS: We performed a comparative analysis with MDF, silicosis, and macular pneumoconiosis (Mac), using autopsy records from 1975 to 1994. RESULTS: Prevalences of having tuberculosis among MDF, silicosis, and Mac were not significantly different, albeit a tendency of higher prevalence in silicosis. Cure rates of tuberculosis were, in order, silicosis < MDF < Mac (P=0. 085). Death rates associated with tuberculosis were, in order, silicosis > MDF=Mac (P=0.911). With respect to the two types of association with tuberculosis, i.e., combined type (tuberculopneumoconiosis) and complicated one (pneumoconiosis with tuberculosis); the former was significantly dominant in silicosis, the latter was significantly dominant in Mac, and intermediate in MDF. As a whole, the complicated type had a tendency of a higher cure rate than the combined type (P=0.071). Although the differences of profiles between the combined and complicated types were not statistically significant, the combined type had a tendency to have longer duration of exposure to dusts, earlier registration for treatment, higher profusion score, and earlier death compared with the complicated type. CONCLUSIONS: From our findings, MDF takes an intermediate position between silicosis and Mac regarding the relationship with tuberculosis. The type of association with tuberculosis rather than the kind of background pneumoconiosis seemed to be more important in light of responsiveness to the treatment.