Sample records for silicotuberculosis
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Establishment of rat model of silicotuberculosis and its pathological characteristic
Dong, Hu; Jing, Wu; Yabo, Yang; Xiaokang, Yang; Wan, Wang; Min, Mu; Wenyang, Wang; Zhaoquan, Chen; Yingru, Xing; Rongbo, Zhang
2014-01-01
Objective: To establish different stages of silicosis rat model complicated with tuberculosis infection, and compare the pathological characteristics and analyze the impact of silicosis on tuberculosis infection. Methods: SD rats were subjected to intratracheal administration of silica with non-exposure method at the 1st, 30th, or 60th day. At the 50th day, the rats were injected with the suspension of H37Rv (a virulent standard strain of Mycobacterium tuberculosis) via tail-vein. After 40 days post-infection, rats were sacrificed, the lung tissues were isolated, and paraffin was embedded and sectioned. The sections were treated using HE staining for structure observation, acid fast stain of Ziehl–Neelsen for bacterial detection, and Warthin–Starry silver staining for displaying the distribution of dust particles. The bacterial load was quantified by colony counting. Results: Primary to tertiary silicosis could be discovered at the 30th, 60th, and 90th day of post-infection. The rats could be infected by injection of M. tuberculosis via tail vein, with tuberculosis load and the degree of lung tissue lesions positively correlated with silicosis. Conclusion: The rat model of silicotuberculosis was established successfully, which facilitated understanding the ‘cross-talk’ of silicosis and tuberculosis during the process they drive each other. PMID:25355545
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Mortality experience of haematite mine workers in China.
Chen, S Y; Hayes, R B; Liang, S R; Li, Q G; Stewart, P A; Blair, A
1990-01-01
The mortality risk of iron ore (haematite) miners between 1970 and 1982 was investigated in a retrospective cohort study of workers from two mines, Longyan and Taochong, in China. The cohort was limited to men and consisted of 5406 underground miners and 1038 unexposed surface workers. Among the 490 underground miners who died, 205 (42%) died of silicosis and silicotuberculosis and 98 (20%) of cancer, including 29 cases (5.9%) of lung cancer. The study found an excess risk of non-malignant respiratory disease and of lung cancer among haematite miners. The standardised mortality ratio for lung cancer compared with nationwide male population rates was significantly raised (SMR = 3.7), especially for those miners who were first employed underground before mechanical ventilation and wet drilling were introduced (SMR = 4.8); with jobs involving heavy exposure to dust, radon, and radon daughters (SMR = 4.2); with a history of silicosis (SMR = 5.3); and with silicotuberculosis (SMR = 6.6). No excess risk of lung cancer was observed in unexposed workers (SMR = 1.2). Among current smokers, the risk of lung cancer increased with the level of exposure to dust. The mortality from all cancer, stomach, liver, and oesophageal cancer was not raised among underground miners. An excess risk of lung cancer among underground mine workers which could not be attributed solely to tobacco use was associated with working conditions underground, especially with exposure to dust and radon gas and with the presence of non-malignant respiratory disease. Because of an overlap of exposures to dust and radon daughters, the independent effects of these factors could not be evaluated. PMID:2328225
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A study of the mortality of Cornish tin miners.
Fox, A J; Goldlbatt, P; Kinlen, L J
1981-01-01
Increased mortality from cancer of the lung has been found in several studies of miners exposed to high levels of radioactivity in underground air. In view of their exposure to raised levels of radiation, we have studied the mortality of a group of men recorded as Cornish tin miners in 1939. Using occupational description, a crude classification of exposure was derived for these miners. The meaningfulness of this classification was supported by differences in mortality from silicosis and silicotuberculosis. A twofold excess of cancer of the lung was found for underground miners, while for other categories mortality from this cause was less than expected. This supports the findings of previous studies on exposure to radon and its daughters. An excess of cancer of the stomach was also observed among underground miners. PMID:7317301
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Murlidhar, V
2015-01-01
Silicosis from secondary exposure is not often reported. This is the first such report of a child with possible silicosis attributable to secondary exposure to sandstone mining in India. Silicosis from secondary exposure has been reported in the gem polishing and slate pencil manufacturing industries in India; however, the stone-mining industry is severely under-researched. No preventive measures have been instituted in the stone-mining industry and children are exposed to respirable silica dust when their mothers take them to their work places. Poverty and lack of accessibility to modern medical facilities promote malnutrition and tuberculosis, two known co-morbid conditions. Stone mining, an export-oriented industry, produces billions of dollars of foreign currency every year. Although there is legislation to protect workers from exploitation, employers disregard the law and the state turns a blind eye by not implementing proper enforcement mechanisms. Silicosis from environmental exposure affects the entire community that lives in stone-mining areas. PMID:26106174
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A study of mortality patterns at a tyre factory 1951-1985: a reference statistic dilemma.
Veys, C A
2004-08-01
The general and cancer mortalities of rubber workers at a large tyre factory were studied in an area of marked regional variation in death rates. Three quinquennial intakes of male rubber workers engaged between January 1946 and December 1960 formed a composite cohort of 6454 men to be followed up. Over 99% were successfully traced by December 1985. The cohort analysis used both national and local rates as reference statistics for several causes. Between 1951 and 1985, a national standardized mortality ratio (SMRN) of 101 for all causes (based on 2556 deaths) was noted, whereas the local standardized mortality ratio (SMRL) was only 79. For all cancers, the figures were 115 (SMRN) and 93 (SMRL), for stomach cancer they were 137 (SMRN) and 84 (SMRL), and for lung cancer they were 121 (SMRN) and 94 (SMRL). No outright excesses against the national norm were observed for other cancers except for larynx, brain and central nervous system and thyroid cancer and the leukaemias. Excesses were statistically significant for cancer of the gallbladder and the bile ducts, for silicotuberculosis (SMRN = 1000) and for the pneumoconioses (SMRN = 706). Deaths from cerebrovascular diseases, chronic bronchitis and emphysema showed statistically significant deficits using either norm. These results from a large factory cohort study of rubber workers, followed for over three decades, demonstrate the marked discrepancy that can result from using only one reference statistic in areas of significant variation in mortality patterns.
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Fielding, Katherine L; Grant, Alison D; Hayes, Richard J; Chaisson, Richard E; Corbett, Elizabeth L; Churchyard, Gavin J
2011-05-01
South Africa has the third highest annual number of new tuberculosis (TB) cases globally. The resurgence of TB which has particularly affected gold miners in South Africa, is attributed to occupational risk factors for TB including silica dust exposure and high HIV prevalence. Isoniazid preventive therapy (IPT) is recommended for individuals at high risk to prevent both HIV-related TB and silicotuberculosis, but global uptake has been poor. We describe the design of a cluster randomised study, "Thibela TB", which compares routine IPT targeted to those identified as at higher risk of TB (due to HIV infection or silicosis) against a "community-wide" approach in which IPT is offered to all employees. The trial is registered with the Current Controlled Trials: Registration number ISRCTN63327174. We describe the rationale for the intervention of community-wide IPT, drawing on studies conducted in 1950-1960s in the pre-HIV era. The design of the study, including the definition of the cluster, is presented and advantages and limitations of such a design are discussed. If successful in reducing TB incidence and prevalence, this trial has potential to make a major contribution to TB control policy in high HIV settings, providing evidence concerning efficacy, and additionally safety and population-level effects on drug susceptibility patterns. Such rigorous evaluation is essential to provide policy makers with an evidence base to guide community-level TB prevention strategies. Copyright © 2010 Elsevier Inc. All rights reserved.
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Hughes, J M; Weill, H; Rando, R J; Shi, R; McDonald, A D; McDonald, J C
2001-04-01
A cohort mortality study of 2670 men in nine North American industrial sand plants resulted in 83 deaths from lung cancer 20 or more years after hire (standardized mortality ratio 139) and 37 deaths from silicosis (including seven from silico-tuberculosis). The lung cancer excess was unrelated to duration of employment and not found in all plants. The primary aim was to determine whether lung cancer risk among these employees was related to quantitative estimates of crystalline silica exposure, after allowance for cigarette smoking. A secondary aim was to do the same for silicosis mortality, partly as a means of validating the estimated levels of exposure. A nested case-referent study was undertaken with cases matched with up to two controls on plant, age and date of first employment from men who survived the case. Exposures were estimated by linking work histories to a job-exposure matrix, undertaken separately. Cigarette smoking information was obtained from medical records and other sources, blind as to case-control status. Matched statistical analyses were conducted using conditional logistic regression. Odds ratios for silicosis mortality were significantly related to cumulative silica exposures and tended to a relationship with category of average crystalline silica concentration, but inconsistently with length of employment. After accounting for a strong effect of cigarette smoking, odds ratios for lung cancer were related to cumulative crystalline silica exposure and to average silica concentration, but not to length of employment. These findings support a causal relationship between lung cancer and quartz exposure after allowance for cigarette smoking, in the absence of cristobalite or other known occupational carcinogens.
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Death in the New Town: Edinburgh's hidden story of stonemasons' silicosis.
Donaldson, K; Wallace, W A; Henry, C; Seaton, A
2017-12-01
The building of the Edinburgh New Town, from the mid-18th to the mid-19th centuries, was a major advance in harmonious and elegant town planning. However, there is anecdotal evidence that it led to the occurrence of an epidemic of silicosis/tuberculosis among the stonemasons. We have reviewed contemporary accounts of the episode and early records of the understanding of silicosis. We have also studied the lung of a contemporary stonemason, preserved in the museum of the Royal College of Surgeons of Edinburgh, and confirmed the presence of silico-tuberculosis in it. The evidence shows that a major epidemic did occur, caused by a combination of factors. The size of the undertaking attracted many stonemasons to Edinburgh over a period of almost 100 years, intensively cutting and dressing stone. The principal stone worked was a very high-quartz sandstone, derived from the local Craigleith quarry, having properties that made it desirable for prestige buildings. However, even before the construction of the New Town, Craigleith sandstone was notorious for its dustiness and the Edinburgh stonemasons worked the stone in unventilated sheds. Stonemasons appeared to be aware of the risk of their trade, but little was known about preventive measures. It appears it was assumed that the risks to stonemasons disappeared after the Craigleith quarry closed, the employers emphasising (without evidence) the lack of health risks in other quarries, and the tragic episode appears to have been forgotten. However, we point to the continuing occurrence of silicosis among stonemasons to the present day; the importance of remembering such episodes is stressed lest the lessons of the past be forgotten.
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A general classification of silicon utilizing organisms
NASA Astrophysics Data System (ADS)
Das, P.; Das, S.
2010-12-01
Silicon utilizing organisms may be defined as organisms with high silicon content (≥ 1% dry weight) and they can metabolize silicon with or without demonstrable silicon transporter genes (SIT) in them(Das,2010). Silicon is the second most abundant element in the lithosphere (27.70%) and it is as important as phosphorus and magnesium (0.03%) in the biota. Hydrated silica represents the second most abundant biogenic mineral after carbonate minerals. Silicon is accumulated and metabolized by some prokaryotes, and Si compounds can stimulate the growth of a range of fungi. It is well known that Si is essential for diatoms. In mammals, Si is considered an essential trace element, required in bone, cartilage and connective tissue formation, enzymatic activities and other metabolic processes. Silicon was suggested to act as a phosphoprotein effector in bone. In mammals, Si is also reported to positively influence the immune system and to be required for lymphocyte proliferation. The aqueous chemistry of Si is dominated by silicic acid at biological pH ranges. Monosilicic acid can form stable complexes with organic hydroxy-containing molecules . Biosilica also has been identified associated with various biomolecules including proteins and carbohydrates. There are main seven groups of silicon utilizing organisms belonging to Gram positive bacteria, algae, protozoa, sponges, fungi, lichens, and monocotyledon plants. In each group again all the members are not silicon utilizing organisms, thus selective members in each group are further classified depending their degree of silicon utilization. Important silicon utilizing bacteria are Mycobacteria, Nocardia, Streptomyces, Staphylococcus, Bacillus, Lactobacillus spp. etc., Important silicon utilizing algae are Centrobacillariophyceae, Pennatibacillariophyceae and Chrysophyceae. Many protozoa belonging to Heterokonta, Choanoflagellida, Actinopoda are well known silicon utilizing microorganisms. Hexactinellida ( glass sponges), Demospongiae and Sclerospongiae are important silicon utilizing sponges. Fungi like Aspergillus, Penicillium, Rhizopus etc. are also silicon utilizing. Candida spp. also belong to silicon utilizing organisms as they are also frequently found in sputum in silicotuberculosis cases. Many monocotyledon plants belonging to Pteridophyta, Magnoliophyta etc. are also well known silicon utilizing organisms. Almost all lichens belong to the group of silicon utilizing organisms.