Small-airways dysfunction in never smoking asbestos exposed Danish plumbers

Summary Among 701 Copenhagen plumbers we examined the lung function of 23 never smokers, who had removed asbestos insulation and intermittently been exposed to high levels of asbestos for about 25 years without being exposed to welding fume. The plumbers had significantly lower TLC, MEF₂₅, MEF₅₀, closing volume and closing capacity in comparison to 23 never smoking electricians without asbestos exposure. There was no reduction in TL_CO. Pulmonary clearance of aerosolized ^99mTc-DTPA was normal indicating that the asbestos had not induced increases in pulmonary epithelial permeability. However, in 11 of the 23 plumbers the ^99m-Tc-DTPA ventilation scintigrams had a slightly irregular and spotty appearance, which together with the results of the lung function tests are suggestive of small airways' dysfunction. None of the subjects had symptoms or clinical signs of lung disease.     

Mortality study of asbestos cement workers

The present study describes cause-specific mortality of asbestos cement workers in the Emilia Romagna region of Italy. The cohort included workers in ten factories, most of which started operating between 1955 and 1965. Asbestos, mainly chrysotile, constituted 10%–20% of the dry component of the mixture. Crocidolite range between 5% and 50% of total asbestos. Asbestos concentrations up to 44 ff/cc were reported prior to 1975, while in recent years they have usually been below 0–1 ff/cc. The cohort included 3341 workers who had at some time been employed in the ten factories under study. Their mortality experience was compared with that of the population resident in Emilia Romagna. Vital status was ascertained at 1989. Seventy-three subjects were lost to followup (2.2%). Mortality from all causes and from all types of cancer was increased in the cohort. Malignant neoplasms of the respiratory tract showed a significant increase (SMR: 134; 90% confidence interval: 101–175; 40 observed) due to lung cancer (SMR: 124; 90% confidence interval: 91–166; 33 observed) and neoplasms of the pleura, mediastinum, and other parts of the respiratory tract (SMR: 602; 90% confidence interval 237–1267; 5 observed). The discrepancy between observed and expected mortality mainly concerned subjects with at least 20 years of employment in the factories. Five more cases of histologically confirmed mesothelioma occurred after the end of follow-up.     

Rounded atelectasis: diagnosis by fine-needle aspiration cytology.

Rounded atelectasis, a rare, benign mass lesion, is most often seen in association with asbestos-related pleural changes. Often a presumptive diagnosis can be made on the basis of characteristic CT and chest radiographic findings. However, not infrequently radiographic imaging fails to differentiate rounded atelectasis from primary bronchogenic carcinoma, a disease which is seen with increased frequency in patients with asbestos exposure. We describe two cases where the diagnosis of rounded atelectasis was made by fine-needle aspiration (FNA) cytology. The cytologic features included abundant pulmonary parenchymal material with thickened alveolar walls containing pulmonary macrophages and connective tissue. It is important to realize that this is a useful positive finding indicating rounded atelectasis, rather than a negative finding suggesting the absence of neoplasm. Needles with a cutting action may be necessary to obtain sufficient material to make the diagnosis of rounded atelectasis.     

几种化合物对石棉诱发肺泡巨噬细胞产生一氧化氮的抑制作用

为了寻求一种适宜的石棉表面改性剂，利用体外细胞培养技术，通过测定培养液中亚硝酸根（ＮＯ－２）含量，观察了茫崖产温石棉对豚鼠肺泡巨噬细胞（ＡＭ）产生一氧化氮（ＮＯ）的诱导作用以及混合稀土、亚硒酸钠、柠檬酸铝对石棉诱发ＡＭ产生ＮＯ的影响。结果显示，温石棉纤维可使培养液中ＮＯ－２浓度升高，并呈明显的剂量反应关系；混合稀土、亚硒酸钠、柠檬酸铝均可抑制石棉诱发ＡＭ产生ＮＯ，而且随上述化合物浓度的升高，抑制作用增强。提示用混合稀土和亚硒酸钠拮抗石棉的致病作用有实际应用的可能。     

石棉相关肿瘤p53基因突变的免疫组化及PCR—SSCP研究

为了分析石棉相关肿瘤ｐ５３基因的突变特点，对石蜡包埋的石棉相关肿瘤ｐ５３基因突变体蛋白的表达进行了免疫组化观察，提取染色体ＤＮＡ，对ｐ５３基因的第５、７、８外显子进行ＰＣＲ－ＳＳＣＰ及测序分析。免疫组化观察发现：在分析的１０例病例中有５例阳性。ＰＣＲ－ＳＳＣＰ分析发现７例（８处）发生突变，其中４处集中在第８外显子上。５例腺癌中有４例发生ｐ５３基因突变。测序发现热点区突变。提示：石棉相关肿瘤ｐ５３基因突变率高。     

Substantiating hazardous exposure to asbestos by examination of pulmonary dust

Summary Substantiation of relevant asbestos risks by microscopic examination sets a lower detection limit at fibres longer than 5 to 10 m and thicker than 0.5 m Such microscopically detectable fibres are, of course, in respect to total quantity the insignificant part of the overall dust burden, but apparently a necessary part of the whole fraction when assessing the relevance of exposure. Until now, no epidemiologically conclusive asbestos risks resulting from occupational exposure have been made known solely with fibre fraction below the microscopic detection limit. Demands for supplementary electromicroscopic examination on the basis of case reports of lung parenchyma damage by fibres of a lower calibre than the microscopic detection limit are, therefore, presently without foundation. The subject examinations reveal that substantiation of asbestos risks with light-optical means, using different methods, provides comparable results. Initially, of course, it is surprising to obtain fluctuations in results of 100000 to 600000 asbestos particles for the same case. However, one must realize that calculations based on intermediate results are responsible for this range of fluctuation, due to the varying degree of asbestos fibre dispersion in the different sections of the lung and, depending on the method of detection used. Interest on the part of everyday occupational medicine and expert opinion is determined by the need to categorize individual cases into different basic classes of risk by referring to relevant morphological facts, such as substantiation of asbestosis or drawing a borderline between persons with occupational risk and those with a non-occupational risk. The subject examinations reveal, using different methods of analysis, equally significant results, which correspond with those published by other authors who used a method which, in terms of expenditure for material and manpower, is also suitable for routine analysis.     

The effects of thermochemotherapy using cyclophosphamide plus hyperthermia on the malignant pleural mesothelioma in vivo

The human malignant pleural mesothelioma is related to the use of asbestos in the majority of cases. Though the use of asbestos has been prohibited since the 1990s, the incidence of pleural mesothelioma is still increasing because of a latency period of at least 20 years. This study investigated the benefit of single therapy with cyclophosphamide or hyperthermia or the combination of both on cells of a human pleural mesothelioma cell line, xenotransplanted subcutaneously in the paw of mice. A CONTROL group received the same volume of physiological saline. The oxygenation of tumours was measured, tumour growth was followed over 3 weeks, immunohistochemical studies and a light and electron microscopic evaluation were performed. Chemotherapy or hyperthermia alone was only temporarily effective. The greatest benefit was achieved using combined thermochemotherapy consisting of cyclophosphamide plus hyperthermia: 50% of this group had partial remissions, and 67% responded to this therapy. After 3 weeks tumours grew again. Superior effects could be achieved by performing additional cycles of chemotherapy or adding another drug or radiation for instance. This study shows promising results in the treatment of malignant pleural mesothelioma.     

三种化合物对石棉致HEL细胞增殖周期及c-fos癌基因转录活性改变的影响

目的寻求一种适宜的石棉表面改性剂。方法利用流式细胞技术测定细胞周期以及Ｎｏｒｔｈｅｒｎ杂交技术测定ｃｆｏｓ癌基因转录活性,观察几种化合物对温石棉促人胚肺（ＨＥＬ）细胞增殖作用的影响。结果将ＨＥＬ细胞与温石棉共同孵育后,其Ｓ期细胞所占比例增加,ｃｆｏｓ癌基因的转录活性也明显增强。用３种化合物预处理的石棉组,其Ｓ期细胞所占比例以及ｃｆｏｓ癌基因的转录活性均低于未处理石棉组。结论用上述３种化合物预处理石棉,均可不同程度地抑制石棉的促细胞增殖作用。     

烟溶液与温石棉对细胞增殖活性的影响

目的　探讨香烟烟雾溶液与温石棉单独及联合作用对细胞增殖活性的影响。方法　将人胚肺（ Ｈ Ｅ Ｌ） 成纤维细胞用不同浓度的烟溶液和温石棉单独及联合作用一定时间后,应用［３ Ｈ］ Ｔｄ Ｒ参入法测定了细胞的增殖能力。结果　低剂量的烟溶液与温石棉单独作用时均可促进细胞的增殖,但较高剂量的烟溶液和温石棉则可抑制细胞的增殖;当二者联合作用时,低剂量的烟溶液与温石棉可协同增加细胞的增殖,而较高剂量的烟溶液与温石棉则只表现为相加作用。结论　烟溶液与温石棉单独及联合作用均可影响 Ｈ Ｅ Ｌ细胞的增殖活性,但其促增殖和抑制增殖能力则随剂量不同而不同。     

Oxidative damage on DNA induced by asbestos and man-made fibers in vitro

Summary We compared the potential of asbestos and man-made fibers to attack DNA by the determination of the yield of 8-hydroxy-2-deoxyguanosine (8-OH-dGuo) under several in vitro conditions. Asbestos induced 6.6–99.8 of 8-OH-dGuo per 10⁵ dGuo in calf thymus DNA after 20 h of incubation, while the levels of 8-OH-dGuo in man-made fibers were low (3.6–9.4). The amounts of 8-OH-dGuo were strongly stimulated by the addition of H₂O₂ in asbestos, but not in man-made fibers. However, the yield of 8-OH-dGuo was induced more than that with asbestos by the further addition of FeSO₄ in attapulgite, fiberglass, potassium titanate whisker, and metaphosphate polymer. The addition of ethylene diamine tetraacetic acid (EDTA) promoted the induction of 8-OH-dGuo with asbestos and H₂O₂. The effects of mannitol (known as a hydroxy radical scavenger) were not dramatic on 8-OH-dGuo induction by all fibers except fiberglass and basic magnesium sulfate whisker, which induced higher amounts after mannitol addition than in these fibers and H₂O₂. Therefore, it was suggested that asbestos could damage DNA, resulting in 8-OH-dGuo as a cause of point mutation, and also several types of manmade fibers had similar effects to asbestos under certain conditions.