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HLA-B18 antigens and protection from pulmonary fibrosis in asbestos workers.

HLA antigens were identified in 64 patients with radiographic asbestosis and 37 matched controls with equivalent asbestos exposure but no radiographic pulmonary fibrosis. A high prevalence of HLA-B18, B27 and Cw2 was found in the controls. This result might indicate that the possessors of these HLA antigens are thus protected from the development of diffuse pulmonary fibrosis from asbestos exposure. Signs of susceptibility were not demonstrated. The radiographic severity and progression of asbestosis were not associated with any of the HLA antigens tested.

Adult↗

First report of asbestos-related diseases in Hong Kong.

There has been no report of malignant mesothelioma or asbestosis in Hong Kong despite the rapid growth of industry in the past few decades. Three patients with malignant pleural mesothelioma and one patient with asbestosis and small cell carcinoma of the lung are reported. All four patients were Chinese in Hong Kong and had a history of occupational exposure to asbestos. Although there is no mining of asbestos in Hong Kong, her rapid industrialization in the past few decades has led to a large population of asbestos-exposed workers in industry. The average annual consumption of crude asbestos (import minus re-export) has grown ten-fold in the past decade to 1.090 tonnes in 1978-79, and the number of workers handling asbestos products was estimated to be 20.000 in 1979. The problem of asbestos related diseases has however been little considered and further epidemiologic studies are warranted.

Adult↗

The early pathogenesis of asbestos-induced lung disease.

This paper presents new findings obtained using animal models on the basic mechanisms of asbestos-induced lung disease. Recent, highly visible reviews on the subject have clearly pointed out that little is known about the cellular mechanisms through which inhaled asbestos fibers cause the well known, debilitating lung disease - asbestosis (i.e. interstitial pulmonary fibrosis). During the past five years, my colleagues and I have published a series of papers in which we have attempted to elucidate, in a rat model of asbestosis, the initial events of 1) asbestos fiber deposition, 2) translocation of fibers to the lung interstitium, 3) the response of pulmonary macrophages and the mechanisms through which these cells are attracted to sites of initial asbestos deposition, and 4) the developmental pathogenesis of the earliest anatomic lesion consequent to asbestos exposure.

Animals↗

[Host factors in asbestos-associated disease. A study in twins (author's transl)].

Observations in two pairs of identical twins illustrate the importance of genetic factors in determining the outcome of exposure to asbestos in relation to pleural plaques and bronchogenic carcinoma. The first pair of twins, laggers with french railroad (S.N.C.F.), were discovered fortuitously, after only several years exposure, to have bilateral pleural plaques and calcification at the same site on the axillary and diaphragmatic surfaces. The second set of twins developed epidermoïd bronchial carcinoma : one at the right hilum, the other postero-basally on the right in 1969 and 1977 respectively. Both were in ship-building and each had been exposed to asbestos in the same yard for 20 years between 1945 and 1965. Radiographs showed left sided pleural calcification and reticular shadowing at the bases in the two cases. These observations show the role of the host in the generation of asbestos disease. They are in keeping with studies on the presence of certain tissue types (HLA B27, and HLA B8) in those with asbestosis and of non-specific auto-antibodies (anti-nuclear factor, rheumatoid factor) in asbestosis, silicosis and the idiopathic pulmonary fibrosis. The relation between genetic factors and asbestos-induced cancer is suggested by the variable susceptibility of different kinds of animals to carcinogenesis in response to asbestos and by the increased inductibility of the enzyme system Aryl-hydrocarbon-hydroxylase in subjects exposed to this air-born contaminant who develop pleural tumours and/or bronchitis. There are only two other publications of bronchial carcinoma in twins in the literature.

Adult↗

Conventional and high-resolution CT in asymptomatic asbestos-exposed workers.

To compare the value of conventional CT (CCT) and high-resolution CT (HRCT) to detect benign asbestos-related diseases, 159 exposed workers with a normal chest radiography were imaged by both techniques. Pleural plaques were detected in a total of 59 cases (37.1%). Ten cases (16.9%) were detected by CCT only and one case (1.7%) by HRCT only. Pulmonary lesions compatible with parenchymal asbestosis were detected by HRCT in 20 cases, whereas CCT showed abnormalities in 45% of these. Rounded atelectasis was equally recognized by both techniques. The results confirm that in a subject with a normal chest radiography, HRCT is a better diagnostic tool to demonstrate lesions of asbestosis. On the other hand, HRCT is insufficient to exclude the presence of pleural plaques. When HRCT does not reveal pleural abnormalities, CCT should be performed.

Asbestosis↗

Pulmonary complications of asbestos exposure.

Except for benign pleural effusion, asbestos-related pulmonary complications, including asbestosis, malignant mesothelioma and bronchogenic carcinoma, usually occur more than 20 years after exposure. Pleural plaques and pleural thickening serve as markers for asbestos exposure, but they are not associated with an increased risk of malignancy. Clinical criteria for the diagnosis of asbestosis include a reliable history of asbestos exposure, an appropriate interval between exposure and disease detection, radiographic evidence of pulmonary fibrosis, decreased vital capacity and diffusing capacity, and bilateral posterior inspiratory crackles. A lung biopsy is indicated only to rule out other causes of interstitial lung disease. A history of dyspnea, pleuritic chest pain, fatigue, weight loss and pleural effusion in a former asbestos worker is suggestive of mesothelioma. Cigarette smoking greatly increases the risk of lung cancer in asbestos workers.

Asbestos↗

[Ecogenetic aspects of the study of phenotypes and levels of beta-aminoisobutyric acid excretion].

The levels of excretion of beta-aminoisobutyric acid (BAIB) in urea were examined in five groups. The distribution of BAIB concentration revealed the existence of high and low excretors in each group. Asbestosis patients had the lowest frequency of high excretors. The BAIB concentration among high excretors was similar for all the groups. The BAIB levels of low excretors varied. The most alike were two children groups, asbestosis patients and the workers from the town Asbest.

Aminoisobutyric Acids↗

[Non-malignant asbestos-related diseases].

Non malignant asbestos diseases are dominated numerically by pleural plaques. This form of circumscribed fibrosis of the parietal pleural is generally asymptomatic and its potential for evolution is weak. More rarely diffuse pleural fibrosis results from disease of the visceral pleura with a secondary fusion of the two pleural layers. Usually it follows a pleural effusion which resolves spontaneously. Its functional effects are sometimes important. The generalised practice of computerized tomographic scanning as a work up for asbestos related disease has revealed the frequent association of this diffuse pleural fibrosis with a particular form of peripheral pulmonary collapse called round atelectasis. Asbestosis or pulmonary fibrosis induced by the inhalation of asbestos has become rarer due to the improvement in working conditions in the asbestos industry. It develops following heavy exposure. The frequency of bronchopulmonary cancer is increased when asbestosis exists although it is not currently possible to say if the two disorders are independent and each is only conditioned by exposure to asbestos or if the two diseases are inextricably linked by the same physiopathological process.

Asbestos↗

Analysis of asbestos bodies in BAL from subjects with particular exposures.

Four patients with asbestos-related diseases and with unusual exposures underwent bronchoalveolar lavage (BAL) for mineralogical analysis. Asbestos bodies (AB) were counted by light microscopy and analyzed by transmission electron microscopy and X-ray energy spectrometry. AB's were found in all cases, after a mean delay from the end of exposure of 27.7 years. Analysis of the core fibers indicated the type of alveolar asbestos burden and was compared with the previous exposures: Pleural plaques due to household exposure to amosite and crocidolite. Pleural plaques due to occult occupational exposure to crocidolite in a coal miner. Asbestosis due to environmental exposure to tremolite in Turkey. Asbestosis, pleural plaques, and peritoneal mesothelioma due to a short, intense exposure to crocidolite. AB counting in BAL and identification of the central fibers by analytical electron microscopy is a useful, non-invasive and reliable method to evaluate the alveolar retention of bio-persistent fibers and to relate them to specific exposures.

Aged↗

Pulmonary asbestos body counts and electron probe analysis of asbestos body cores in patients with mesothelioma: a study of 25 cases.

Malignant mesotheliomas of the pleura and peritoneum are well-recognized risks of asbestos exposure. We determined the asbestos body content of the lungs from 24 cases of malignant mesothelioma (19 pleural, five peritoneal) and compared such to the content of lungs from 50 consecutive adult autopsies and four cases of overt asbestosis using a Clorox-digestion concentration technique. The cores of 90 asbestos bodies were examined by energy dispersive x-ray analysis and compared with similar data from 120 standard asbestos fibers and 20 fiberglass fibers. The malignant mesothelioma patients had asbestos body counts intermediate between those of the general population and those of patients with asbestosis, although some of the mesothelioma cases overlapped with the general population. These latter cases often lacked an identifiable occupational exposure to asbestos. EDXA studies demonstrated an amphibole core in 88 of the 90 asbestos bodies (amosite or crocidolite in 80 of 88, anthophyllite or tremolite in eight of 88), and chrysotile in two instances.

Adult↗

Pneumoconiosis in a vermiculite end-product user.

BACKGROUND: Vermiculite is a silicate used as an insulating agent, soil additive, and carrier for chemicals and fertilizers. It is currently perceived to have no adverse effects to "end-product" users. An 82-year-old man presented with complaints of progressive dyspnea on exertion. METHODS: A clinical evaluation included a chest radiograph, complete pulmonary function testing, CT scan of the thorax, and comprehensive occupational and environmental history. RESULTS: The patient had clinical and radiographic features of advanced pulmonary interstitial fibrosis. The presence of calcified pleural plaques, together with the other clinical and radiographic features, strongly supported a diagnosis of asbestosis. His only significant exposure was to vermiculite used in the workplace for several hours per day from 1970 to 1987. CONCLUSIONS: This case represents the first report of an end-product vermiculite-user with probable asbestosis, and together with recent similar findings in a vermiculite expansion plant worker, requires further epidemiologic investigations.

Aged↗

Multiplane gallium tomography in assessment of occupational chest diseases.

Gallium-67 scintigraphy is helpful in the evaluation of inflammatory, respiratory diseases. Single-photon emission computed tomography (SPECT) provides three-dimensional tomographic reconstruction of radioisotope distribution in the body. The addition of SPECT to gallium-67 scanning in 27 patients demonstrated an improvement in the sensitivity for detecting the presence and extent of interstitial occupational lung disease. This technique may provide earlier detection of parenchymal lung changes than can the chest x-ray and planar scanning in some patients with asbestosis. Findings in six patients with asbestosis are reported.

Adult↗

Bronchiolar and alveolar lesions in the pathogenesis of crocidolite-induced pulmonary fibrosis in mice.

Asbestosis is generally considered to result in restrictive pulmonary disease associated with interstitial fibrosis. Recently, however, attention has focused upon bronchiolar lesions and concomitant obstruction to air flow. The responses of conducting airways and alveoli were studied over a 20 week period following instillation of crocidolite to mice. The location of the lesions and the sequential inflammatory changes were studied by bronchoalveolar lavage, light and electron microscopy; regenerative activity was monitored by autoradiographs. Within 48 h there was multifocal necrosis of bronchiolar epithelium, maximal at bifurcations where longer fibres tend to adhere. Subsequently, intralumenal exudates were overgrown by epithelium and incorporated into the bronchiolar connective tissue where active peribronchiolar granulomas persisted until 20 weeks. Alveolar lesions were located predominantly in peribronchiolar air sacs and at the junctions of bronchioles and alveolar ducts. Focal acute injury of type 1 cells and transepithelial passage facilitated transport of short asbestos fibres to the interstitium where they were phagocytozed by macrophages. Regenerative activity was prompt with active division of type 2 epithelial cells. Biochemically, collagen increased after 4 weeks, when fibrosis was predominantly located in the bronchiolar lumens and in peribronchiolar connective tissue with lesser amounts in the centrilobular alveolar interstitium. The results suggest that the longer fibres induce bronchiolar injury and a more severe fibrotic pattern similar to the recently described changes seen in human asbestosis.

Animals↗

Clearance of 99m-technetium-labelled DTPA in asbestos-exposed subjects without clinical or radiological evidence of interstitial lung disease.

The half-time clearance of an inhaled aerosol of 99m-technetium-labelled diethylene triamine pentacetate from lung to blood (T1/2LB) was measured using a gamma camera in 20 non-smoking subjects (mean age 54, range 40-69 years) with previous occupational asbestos exposure, but no clinical or radiological evidence of asbestosis, and 20 non-smoking normal subjects (mean age 54, range 40-62). Mean T1/2LB was 44.7 minutes (range 12-102) in exposed subjects, significantly less than 57.2 minutes (range 30.5-109) in normal subjects (P less than 0.05). There was no correlation between age and T1/2LB in either group. In exposed subjects T1/2LB showed a weak rank correlation with the membrane component of DLco (Dm) (r = 0.40, P less than 0.05) but no significant correlation with FVC, TLC, DLco, Kco, resting Pao2 or change in Pao2 on exercise. In six exposed subjects T1/2LB was shorter than in any of the normal subjects. These six did not differ from the other 14 exposed subjects in any physiological variables. T1/2LB is abnormal in some asbestos-exposed subjects without clinical, radiological or physiological evidence of asbestosis. Follow-up will show whether it is an early indicator of development of interstitial lung disease.

Adult↗

Prevention of asbestos-induced cell death in rat lung fibroblasts and alveolar macrophages by scavengers of active oxygen species.

Cell injury and inflammation caused by asbestos are critical to the pathogenesis of pulmonary fibrosis (asbestosis). Our goal in studies here was to investigate the possible modulation of asbestos-related cell death using antioxidants in both target and effector cells of asbestosis. After exposure to crocidolite asbestos at a range of concentrations (2.5-25 micrograms/cm2 dish), the viability of a normal rat lung fibroblast line (RL-82) and freshly isolated alveolar macrophages (AM) was determined by exclusion of trypan blue and nigrosin, respectively. In comparison to fibroblasts, AM were more resistant to the cytotoxic effects of asbestos. Cytotoxic concentrations of asbestos then were added to both cell types in combination with the antioxidants, superoxide dismutase (SOD), a scavenger of superoxide (O2-.), and catalase, an enzyme scavenging H2O2. Dimethylthiourea (DMTU), a scavenger of the hydroxyl radical (OH.) and deferoxamine, an iron chelator, also were evaluated in similar studies. Results showed significant dosage-dependent reduction (P less than 0.001) of asbestos-associated cell death with all agents. In contrast, asbestos-induced toxicity was not ameliorated after addition of chemically inactivated SOD and catalase or bovine serum albumin. Results above suggest asbestos-induced cell damage is mediated by active oxygen species. In this regard, the iron associated with the fiber and/or its interaction with cell membranes might be critical in driving a modified Haber-Weiss (Fenton-type) reaction resulting in production of OH(.).

Animals↗

Amiodarone pneumonitis diagnosed by gallium-67 scintigraphy.

A 75-year-old man presented with fever, dyspnoea, chest pain and findings suggestive of severe pneumonia including hypoxia and bilateral chest infiltrates. He was given antibiotics without significant effect. He took long-term amiodarone therapy for persistent atrial arrhythmias and also had a history of asbestosis with pre-existing pulmonary interstitial fibrosis. Pulmonary gallium-67 scintigraphy revealed extensive uptake of tracer throughout both lungs consistent with a diagnosis of amiodarone pneumonitis. Treatment of the drug reaction by drug withdrawal and corticosteroids resulted in marked clinical improvement. Pulmonary gallium-67 scintigraphy is a sensitive, but non-specific aid in the diagnosis of this drug effect. It proved valuable in our patient who additionally had asbestosis.

Journal Article↗

Diseases associated with asbestos exposure. Diagnostic perspectives in forensic pathology.

Asbestos, a fibrous mineral, has unique physical and chemical properties, including resistance to heat, acids, and other chemicals; flexibility; and great tensile strength. The fibers subdivide into unit fibrils of molecular dimensions, resulting in a vast mineral surface area which has a direct bearing on its unusual features and its numerous applications. Its biological effects, which include fibrogenesis and carcinogenesis, may be related to the cellular reaction, to its large specific surface, or to the size and shape of the fibers. Its oncogenic action may be multiplied by other carcinogens, principally cigarette smoking. There is clinical, pathologic, and epidemiologic evidence that exposure to asbestos, following a long latent period, constitutes an important health hazard. Direct occupational exposure, followed by a long lapsed period after the initial exposure, is associated with pleural plaques and pleural effusion, pulmonary parenchymal fibrosis (asbestosis), pulmonary carcinoma, pleural and peritoneal mesothelioma, and other neoplasms. Indirect exposure may also entail an increased risk of lung disease or mesothelioma or both. Medicolegal investigation of suspected cases includes a lifetime occupational history, clinical history including smoking habits, radiological findings, clinical evidence of asbestosis, and may require detection of asbestos tissue burden.

Asbestos↗

A quantitative and histological study on pulmonary effects of asbestos exposure in general autopsied lungs.

We demonstrated the distribution of asbestos bodies (ABs) in the lungs of 656 consecutive autopsy cases by KOH digestion method. Nine patients including one case with asbestosis had more than a thousand ABs. These patients were all blue-collar workers except the two cases without occupational history. The tissue sections for these patients revealed the constant presence of more than one or two ABs. In addition, five of these subjects had parenchymal and/or peribronchiolar fibrosis. On the basis of the result of AB counts, we selected 17 subjects for enumeration and typing of asbestos fibers (AFs). The number of AFs roughly correlated with that of ABs. However, the ratio of AFs to ABs ranged from 13 to 3,700. The fiber types in our selected subjects were almost always amphibole (crocidolite, amosite). These findings indicate that modest or secondary exposure to asbestos causes virtual asbestosis to several subjects among the general population.

Adult↗