Concentration of hydroxyproline in blood: a biological marker in occupational exposure to asbestos and its relationship with Pi*Z and Pi*S polymorphism in the alpha-1 antitrypsin gene

BACKGROUND: Hydroxyproline (OHP) is one of the most abundant amino acids in collagen and, in general, it provides a good measure of overall collagen catabolism. METHODS: Asbestos workers suffering from asbestosis (cases n = 85); asbestos exposed workers without asbestosis (exposed controls, EC, n = 86), and non-exposed population (non-exposed controls, NEC, n = 122) were studied. The concentration of free OHP in whole blood was measured following the Pico-Tag procedure. RESULTS: Concentration of OHP in blood was significantly different in the three groups studied (P < 0.001), being higher in cases (19.8 +/- 14.7 micromol/L) than in EC (16 +/- 12.4) and NEC (13.5 +/- 6.7). When all individuals were grouped and stratified by the Pi*S and Pi*Z polymorphisms in the alpha-1-antitrypsin gene, the highest OHP levels were detected in the Pi*S homozygotes, one of the asbestosis-at risk-genotypes (Pi*S homozygotes, x = 24.5 +/- 11.7; Pi*S heterozygotes, x = 16.6 +/- 10.0; wild type, wt, x = 15.9 +/- 11.8). CONCLUSIONS: Blood OHP concentration could be used for monitoring human exposure to asbestos, either as a marker for occupational monitoring or as an additional clinical parameter in diagnostic exploration of asbestosis.     

Review on the adverse health effects of asbestiform antigorite,a non‐regulated asbestiform serpentine mineral

Background

Although antigorite is generally described as platy, its fibrous (asbestiform) variant is present widespread in serpentinite rocks. In addition to its primarily fibrous occurrence, asbestiform antigorite may also be formed from serpentinite with massive appearance during tunneling and mining. It is not of commercial interest, but exposure may occur in the certain environments.

Methods and Results

Detailed studies of the structural features of this antigorite type revealed characteristics closely related to those of chrysotile. Therefore, it is plausible that this serpentine mineral may present a similar health risk for exposed subjects. This is in agreement with results from clinical and animal studies, as well as in vitro experiments showing the cytotoxic, fibrogenic, and carcinogenic potential of antigorite, similar to that of chrysotile and amphibole asbestos.

Conclusions

Current evidence supports a need for an update to existing regulations to include unregulated asbestiform antigorite, similar to regulatory measures taken for asbestos.

     

Asbestos-related x-ray changes in foundry workers

Michigan has a statewide mandatory occupational disease reporting system. As part of that system, reports are received from hospitals, physicians, death certificates, the workers' compensation bureau, and company medical departments. Based on this reporting, the State of Michigan has a special emphasis program for the surveillance of silicosis, a known disease outcome among foundry workers. From 1985–1996, 115 cases reported to the State Surveillance System as silicosis, pneumoconiosis not specified, or pulmonary fibrosis were reclassified as having asbestos related x-ray changes after a B-reader interpretation of each case's chest x-ray. During this same period there were an additional 697 reports confirmed as silicosis and 6,724 cases reported to the surveillance system as asbestosis. Among the 115 reports reclassified as having asbestos-related x-ray changes without evidence of silicosis-related x-ray changes, 54 had worked in foundries. Only 7 (14.8%) of these individuals had their primary work in maintenance in the foundry; 40 (85.1%) had their primary foundry work in a production job; and for 10 individuals the occupation was not known. Asbestos has been used in foundries on pipe laggings, boiler coverings, as insulation in fan housings, in gloves, aprons and curtains, as insulation in cupolas, and in ladles and insulation in sand molds. Clinicians caring for foundry workers need to be aware that asbestos-related x-ray changes are not uncommon in this population and asbestos exposure should be considered as one of the carcinogens contributing to the known increased risk of lung cancer among foundry workers. Am J. Ind. Med. 34:197–201, 1998. © 1998 Wiley-Liss, Inc.     

The glutathione S-transferase θ and μ deletion polymorphisms in asbestosis

The glutathione S-transferases (GSTs) catalyze the conjugation of a wide variety of reactive, electrophilic substrates with glutathione, facilitating their excretion. There is also evidence that GSTs can catalyze glutathione conjugation of lipid radicals as well as act in the generation of leukotriene inflammatory mediators. Studying construction carpenters screened for the presence of asbestos-related diseases, we have previously reported that the constitutional deletion of GSTM1 (the gene coding for glutathione S-transferase class mu) is associated with an increased risk of asbestos-related interstitial lung disease, measured radiographically. In the current work, we have further studied this group of workers, investigating the distribution of a novel deletion polymorphism in the newly described GSTT1 gene, that codes for the GST class theta enzyme. A total of 666 carpenters were studied, and 124 (19%) had the deleted genotype. There was no association between the GSTT1 deletion and the radiographic diagnosis of either asbestos-related pleural or parenchymal disease. The GSTM1 deletion remained associated with the presence of x-ray evidence of asbestosis after adjustment for GSTT1 genotype. The GSTM1 null genotype was also associated with a family history of any malignancy. These data suggest that the association of polymorphic GSTs with asbestos-induced radiographic changes is specific for substrates of the GST class mu. Am. J. Ind. Med. 31:274–279, 1997. © 1997 Wiley-Liss, Inc.     

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. Am. J. Ind. Med. 31:693–698, 1997. © 1997 Wiley-Liss, Inc.     

Lobe of origin and histologic type of lung cancer associated with asbestos exposure in the carotene and retinol efficacy trial (CARET)

Lower lobe origin and histologic diagnosis of adenocarcinoma have been described as useful parameters for attributing lung cancer to prior asbestos exposure. To assess whether these characteristics differed between asbestos-exposed individuals and smokers, we evaluated lobe of origin and histologic type of tumors in 78 asbestos-exposed and 214 nonexposed heavy smokers developing lung cancer during the Carotene and Retinol Efficacy Trial (CARET), a prospective cancer chemoprevention trial. Most tumors in both cohorts, regardless of radiographic fibrosis at baseline, originated in upper lobes, representing 67% in asbestos-exposed and 80% in smokers, respectively (adjusted OR for lower lobe = 1.41; 95%CI = 0.69–2.91). Adenocarcinoma represented 32% of lung tumors in the asbestos cohort, and 30% in the smoking cohort (adjusted OR = 0.78; 95%CI = 0.40–1.55), and was inversely associated with radiographic fibrosis (adjusted OR = 0.19; 95%CI = 0.06–0.62). We conclude that neither anatomic site nor histologic cell type of tumors distinguishes effectively between smoking and asbestos as causal factors in development of lung cancer. Am. J. Ind. Med. 32:582-591, 1997. © 1997 Wiley-Liss, Inc.     

Professor Matthew Stewart: Asbestosis research 1929–1934

Matthew Stewart, Professor of Pathology at Leeds University, developed an interest in asbestosis during the late 1920s. In 1929, the Medical Research Council (MRC), encouraged by an advisory committee, funded research into asbestosis at Leeds University. Stewart supported by physicians designed a program of clinical, radiological and physiological studies to follow up Merewether's affected asbestos workers. Unfortunately, this met with opposition from industry, and the Home Office Factory Department was reluctant to assist, so it was abandoned. Industry did, however, cooperate with Stewart's studies on the effects of exposing guinea pigs in the factory environment, but this led to little in the way of publication. The failure of the Leeds School to realize its potential in investigating the effects of asbestos in humans, results in part from the discouragement it received and in part from the limited time and energies available to persons with a wide range of active interests. Some 45 years were to elapse before the MRC were enabled to carry out an analysis of the clinical, radiological and physiological data of a population of asbestos workers. Am. J. Ind. Med. 32:562–569, 1997. © 1997 Wiley-Liss, Inc.     

螺旋CT诊断胸膜斑的临床价值

目的：研究胸膜斑的螺旋CT表现,提高诊断和鉴别诊断水平。材料和方法：回顾性分析与石棉粉尘密切接触的42例胸膜斑的螺旋CT表现。结果：42例中,螺旋CT发现胸膜斑407个,其中透明型/非钙化型胸膜斑250个、钙化型胸膜斑36个和混合型胸膜斑121个;单侧10例、双侧32例;单发胸膜斑5例,多发胸膜斑37例;最大胸膜斑长4.2cm,厚1.2cm;胸膜斑的形状多种多样;钙化型和混合型胸膜斑内可见不同形态的钙化;胸膜斑多位于中、下胸部前或后外侧胸壁,肋骨下方28例（66.7%）,侵犯双侧膈顶10例,心包4例,合并肺纤维化4例,6例增强扫描胸膜斑未见增强;肺尖和肋膈角不受累。正确诊断42例,正确诊断率100%。结论：螺旋CT能清晰地显示胸膜斑的部位、分布、范围、形态、大小、密度及其毗邻关系,结合石棉粉尘接触史,能与其他胸膜增厚病变鉴别,明确诊断。对胸膜斑/石棉肺,螺旋CT是最佳的影像学检查方法。     

Unrecognized asbestos-induced disease

It is being slowly recognized that there is serious under-reporting of cancers that are occupationally related, in the sense that they would not have occurred without the occupational exposure. Data from the Workers' Compensation Boards of New South Wales in Australia and British Columbia in Canada relating to disease attributable to asbestos exposure indicate that in both jurisdictions the ratio of lung cancer cases to mesothelioma cases is much lower than epidemiological studies indicate must be occurring. Over the period from 1980 to 1994, if both jurisdictions are considered together, about 1,207 cases of lung cancer that would not have occurred without asbestos exposure went unrecognized as occupationally related. The data also suggest that it is unlikely that radiological asbestosis should be regarded as a necessary condition for there to be an increased risk of lung cancer following asbestos exposure. © 1996 Wiley-Liss, Inc.