Evaluation of trace elements in lung samples from coal miners using neutron activation analysis

In this study, instrumental neutron activation analysis was applied to the determination of Sc, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Th, and U in lung samples from miners working in coal mines located in the state of Santa Catarina, Brazil. These results were compared to those from a control group constituted of healthy individuals. The results showed that the elements determined exhibit considerable intersubject variability within a single group of individuals and the mean values of concentrations in miners’ lungs were higher than those of normal individuals. Lung samples presented U concentrations varying from 11 to 890 Μg/kg. Therefore, for some samples, the contribution of the uranium fission products in the analysis of La, Ce, Nd, and Sm was considered by determining the interference correction factors. The accuracy of the results was evaluated by analyzing certified reference materials.     

Explanatory models of medically unexplained symptoms: a qualitative analysis of the literature

Background Medically unexplained symptoms (MUS) are common in primary health care. Both patients and doctors are burdened with the symptoms that negatively affect patients' quality of life. General practitioners (GPs) often face difficulties when giving patients legitimate and convincing explanations for their symptoms. This explanation is important for reassuring patients and for maintaining a good doctor-patient communication and relationship.Objective To provide an overview of explanatory models for MUS.Study design We performed a systematic search of reviews in PsycINFO and PubMed about explanatory models of MUS. We performed a qualitative analysis of the data according to the principles of constant comparative analysis to identify specific explanatory models.Results We distinguished nine specific explanatory models of MUS in the literature: somatosensory amplification, sensitisation, sensitivity, immune system sensitisation, endocrine dysregulation, signal filter model, illness behaviour model, autonomous nervous system dysfunction and abnormal proprioception. The nine different explanatory models focus on different domains, including somatic causes, perception, illness behaviour and predisposition. We also found one meta-model, which incorporates these four domains: the cognitive behavioural therapy model.Conclusion Although GPs often face difficulties when providing explanations to patients with MUS, there are multiple explanatory models in the scientific literature that may be of use in daily medical practice.     

A few north Appalachian populations are the source of European black locust

The role of evolution in biological invasion studies is often overlooked. In order to evaluate the evolutionary mechanisms behind invasiveness, it is crucial to identify the source populations of the introduction. Studies in population genetics were carried out on Robinia pseudoacacia L., a North American tree which is now one of the worst invasive tree species in Europe. We realized large‐scale sampling in both the invasive and native ranges: 63 populations were sampled and 818 individuals were genotyped using 113 SNPs. We identified clonal genotypes in each population and analyzed between and within range population structure, and then, we compared genetic diversity between ranges, enlarging the number of SNPs to mitigate the ascertainment bias. First, we demonstrated that European black locust was introduced from just a limited number of populations located in the Appalachian Mountains, which is in agreement with the historical documents briefly reviewed in this study. Within America, population structure reflected the effects of long‐term processes, whereas in Europe it was largely impacted by human activities. Second, we showed that there is a genetic bottleneck between the ranges with a decrease in allelic richness and total number of alleles in Europe. Lastly, we found more clonality within European populations. Black locust became invasive in Europe despite being introduced from a reduced part of its native distribution. Our results suggest that human activity, such as breeding programs in Europe and the seed trade throughout the introduced range, had a major role in promoting invasion; therefore, the introduction of the missing American genetic cluster to Europe should be avoided.     

The genotoxic risk of underground coal miners from Turkey

A cytogenetic monitoring study was carried out on a group of workers from a bituminous coal mine in Zonguldak province of Turkey, to investigate the genotoxic risk of occupational exposure to coal mine dust. Cytogenetic analysis, namely sister chromatid exchanges (SCEs), chromosomal aberrations (CAs) and micronucleus (MN) tests were performed on a strictly selected group of 39 workers and compared to 34 controls matched for gender, age, and habit. Smoking and age were considered as modulating factors. Both SCE and CA frequencies in coal miners appeared significantly higher than in controls. Similarly, there was a significant increase in the frequency of total micronuclei in exposed group as compared to control group. The effect of smoking on the level of SCE and MN was significant in the control group. A positive correlation between the age and the level of SCE was also found in controls. The frequencies of both SCE and CA were significantly enhanced with the years of exposure. The results of this study demonstrated that occupational exposure to coal mine dust leads to a significant induction of cytogenetic damage in peripheral lymphocytes of workers engaged in underground coal mining.     

The genotoxic risk of underground coal miners from Turkey

A cytogenetic monitoring study was carried out on a group of workers from a bituminous coal mine in Zonguldak province of Turkey, to investigate the genotoxic risk of occupational exposure to coal mine dust. Cytogenetic analysis, namely sister chromatid exchanges (SCEs), chromosomal aberrations (CAs) and micronucleus (MN) tests were performed on a strictly selected group of 39 workers and compared to 34 controls matched for gender, age, and habit. Smoking and age were considered as modulating factors. Both SCE and CA frequencies in coal miners appeared significantly higher than in controls. Similarly, there was a significant increase in the frequency of total micronuclei in exposed group as compared to control group. The effect of smoking on the level of SCE and MN was significant in the control group. A positive correlation between the age and the level of SCE was also found in controls. The frequencies of both SCE and CA were significantly enhanced with the years of exposure. The results of this study demonstrated that occupational exposure to coal mine dust leads to a significant induction of cytogenetic damage in peripheral lymphocytes of workers engaged in underground coal mining.     

Experience with the roentgenodiagnosis of disturbances of respiratory function in coal miners

The paper is concerned with the results of roentgenofunctional investigation of 293 miners, among them there were 63 patients with dust bronchitis and 230 patients with the main types of dust disease (anthracosis, silicosis and anthracosilicosis). Two-stage roentgenopneumopolygraphy (RPPG) with a chess grid and spiral pneumoroentgenography (SPRG) with a spiral grid were employed. Respiratory dysfunction in patients with pneumoconiosis depended on an x-ray and morphological type of fibrosis and stage of disease rather than on its type. The formation of zones of emphysematous inflation in the apical area, in the upper and middle regions of the lungs was revealed, however signs of basal emphysema were ++undetectable. Analysis of RPPG and SPRG findings has shown that unlike pneumoconiosis, dust bronchitis is characterized by earlier development of respiratory dysfunction of more noticeable type, particularly in early signs of disease.     

DNA adducts in coal miners: association with exposures to diesel engine emissions

The potential carcinogenic effects of exposure to diesel engine emissions (DEE) are of growing concern. Due to the use of diesel equipment in underground mines, DNA adducts in peripheral blood mononuclear cells have been measured using the ³²P-postlabelling technique in workers from two coal mines (A, B)in NSW, Australia, before and after a period of more intense exposure (long wall change out, LWCO). DNA adducts were readily detected in all workers. At Mine A, in the 89 participants before LWCO, no significant difference was found among the groups categorized by exposure levels. However, significantly higher concentrations of total DNA adducts were observed in the specific job categories, ‘miners and loadmen’, and ‘machinemen, drivers and shiftmen’ and in the smoking group. On comparing total DNA adducts before and after LWCO in a small number of workers, a significant increase was also found. At Mine B, before or after LWCO, the total DNA adduct levels showed no significant difference among groups categorized by exposure conditions, smoking status, job categories and job time length. However, the total DNA adducts for the 61 subjects were significantly increased (geometric means) from 297 to 389 amol lg^?1 DNA after LWCO (p < 0.0001, paired t test). Some individual adducts were also elevated to a greater extent (p < 0.05, paired non-parametric test, Wilcoxon signed rank test). Furthermore, using generalized estimating equations for adjusting all factors across the observation period, no particular factor showed any significant interactive effects. Given the association of exposure to DEE with lung cancer and the apparent increase in adducts during a period of intense DEE exposures it would be prudent to pay particular attention to keeping exposures as low as possible, especially during LWCO operations.     

Explanatory coherence and empirical adequacy: The problem of abduction, and the justification of evolutionary models

Foundationalist theories of justification for science were undermined by the theory-ladeness thesis, which has affinities with coherentist epistemologies. A challenge for defenders of coherentist theories of scientific justification is to specify coherence relations relevant to science and to show how these relations make the truth of their bearers likely. Coherence relations include characteristics that pick out better explanations in the implementation of abductive arguments. Empiricist philosophers have attacked abductive reasoning by claiming that explanatory virtues are pragmatic, having no implications regarding truth. However, empiricist's basic beliefs are subject to the same challenges facing abduction, both of which can be met by citing causally coherent etiologies, which are commonplace in biological explanations, and by demonstrating the relevance of causal coherence to truth.     

A comparative study of physiological strain of underground coal miners in India

Ninety-eight healthy underground coal miners aged between 23-58 years were studied during their activity period. Physiological strain of different category of miners in terms of heart rate was monitored continuously with heart rate monitor that revealed the tasks as heavy to very heavy for them. Oxygen consumption was measured directly by using oxylog-2 machine that corresponded to metabolic costs for different activities ranging from 4.96 kcal/min to 5.47 kcal/min. The mean relative aerobic strain varied from 47.4%-56.8%--depicting acceptable level of physical strain was well encroached by the miners who irrespective of ages and categories showed poor recovery responses. This entails that miners are exerting themselves beyond their capacities where inevitably older workforce face the maximum burden.     

Non-alcoholic steatohepatitis and animal models: Understanding the human disease

Non-alcoholic fatty liver disease includes a broad spectrum of liver abnormalities ranging from simple steatosis to non-alcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma. Patients with primary NASH have the metabolic (or insulin resistance) syndrome, condition typically associated with obesity, diabetes, hyperlipidemia and hypertension. To understand the mechanisms implicated in development of NASH, animal models of non-alcoholic fatty liver disease have been generated. These have greatly improved our understanding of some of the aspects of this disease. The challenge now is to identify the common mechanisms between the animal models and humans, which could eventually lead to a better prognosis and development of novel therapeutic strategies.     

Some compartmental models of the root: steady-state behavior

Plots of the pressure difference (DeltaP) applied to plant roots vs. the resulting volume flow rate (Q(v)) often exhibit an anomalous offset that has been difficult to explain. The present analysis suggests that solute build-up in two- and three-compartment models of the root cannot account for this offset. The Ginsburg-Newman three-compartment model explains the offset in terms of differing reflection coefficients for the membranes bounding the intermediate compartment. This model appears more promising, but it predicts a minimum in the plot of xylem-sap osmotic pressure vs. Q(v)which is not observed in practice. Fiscus hypothesized that an internal asymmetric distribution of non-mobile solutes is responsible for the offset. In the present study, this hypothesis is incorporated into a four-compartment model of the root that is conceptually related to the three-compartment model of Miller. But according to the four-compartment model, the asymmetric solute distribution does not arise because of solvent drag. Rather the anomalous offset is associated with a concentration gradient of photoassimilates (the non-mobile solutes) that exists in the absence of volume flow, and which drives the diffusive transport of these solutes from the stele to the cortex via endodermal plasmodesmata. This model is consistent with the existence of radial symplastic osmotic-pressure gradients, and it appears to have greater explanatory power than the Ginsburg-Newman model. In particular, it suggests explanations for diurnal variations in DeltaP-Q(v)curves, as well as the effects of changing external solute concentrations. It also shows how the overall root reflection coefficient can be less than unity, even when the cell membranes are effectively ideally semipermeable, and there is negligible extracellular transport of water and solutes. The model makes a number of experimentally testable predictions.