Oxidative Stress From Exposure to the Underground Space Environment

Progress in biological and medical research in the deep underground: an update

As the growing population of individuals residing or working in deep underground spaces for prolonged periods, it has become imperative to understand the influence of factors in the deep underground environment (DUGE) on living systems. Heping Xie has conceptualized the concept of deep underground medicine to identify factors in the DUGE that can have either detrimental or beneficial effects on human health. Over the past few years, an increasing number of studies have explored the molecular mechanisms that underlie the biological impacts of factors in the DUGE on model organisms and humans. Here, we present a summary of the present landscape of biological and medical research conducted in deep underground laboratories and propose promising avenues for future investigations in this field. Most research demonstrates that low background radiation can trigger a stress response and affect the growth, organelles, oxidative stress, defense capacity, and metabolism of cells. Studies show that residing and/or working in the DUGE has detrimental effects on human health. Employees working in deep mines suffer from intense discomfort caused by high temperature and humidity, which increase with depth, and experience fatigue and sleep disturbance. The negative impacts of the DUGE on human health may be induced by changes in the metabolism of specific amino acids; however, the cellular pathways remain to be elucidated. Biological and medical research must continue in deep underground laboratories and mines to guarantee the safe probing of uncharted depths as humans utilize the deep underground space.

Pulmonary Functions and Oxidative Stress Biomarkers Among Silica-Exposed Foundry Workers

OBJECTIVE

To investigate the changes of the ventilatory function tests and the oxidative stress biomarkers among silica-exposed foundry workers.

METHODS

The exposed group included 70 workers in an iron foundry. The nonexposed group included 40 subjects from Kasralainy outpatient clinic. Both groups were subjected to history taking, clinical examination, chest radiograph, spirometry, urinary silica, serum malondialdehyde (MDA), glutathione peroxidase (GPx), and 8-hydroxydeoxyguanosine (8-HdG).

RESULTS

Higher urinary silica, serum MDA and serum 8-HdG, whereas lower serum GPx and ventilatory functions were detected in the exposed group compared with the controls. All parameters correlated with urinary silica. The exposed silicotic subgroup had increased work duration, urinary silica, serum MDA, and serum 8-HdG, and decreased serum GPx and ventilatory functions compared with non-silicotic subgroup.

CONCLUSION

Oxidative stress biomarkers were abnormal with impairment of ventilatory functions among silica-exposed workers.

Assessment of Genetic Damage in Coal Miners of Punjab, Pakistan

Coal miners are continuously exposed to coal mine dust and airborne particulate that act as a potential risk to their health. The present study evaluates the DNA damage in coal miners using the Buccal Micronucleus Cytome (BMCyt) assay. The samples of the blood and buccal epithelial cells of 40 coal miners and 20 control subjects were taken from coal mines of Pail and Padhrar, Pakistan, to establish buccal anomaly frequencies of metal levels in the blood. Besides this, work history and duration hours were also analyzed. Results revealed that micronucleus frequencies positively correlated with the metal concentrations in the miner's blood. The change in the extent of nuclear damage per unit change in the year was 0.170 for micronuclei; however, with addition in each year of working experience, nuclear buds and broken egged nuclei increased by 0.316 and 0.194 units, where each year increases karyolysis by 0.349 units and karyorrhexis by 0.308 units, respectively. An increase in work hours and working years was positively correlated with cytogenetic damage. Nuclear damage in coal miners due to occupational exposure is obvious and increases with increasing work experience. Hence, the Buccal Micronucleus Cytome assay has proved to be an effective cytogenetic biomonitoring tool for assessing genetic and nuclear damage in coal miners.

Geochemistry and oxidative potential of the respirable fraction of powdered mined Chinese coals

This study evaluates geochemical and oxidative potential (OP) properties of the respirable (finer than 4 μm) fractions of 22 powdered coal samples from channel profiles (CP₄) in Chinese mined coals. The CP₄ fractions extracted from milled samples of 22 different coals were mineralogically and geochemically analysed and the relationships with the OP evaluated. The evaluation between CP₄/CP demonstrated that CP₄ increased concentrations of anatase, Cs, W, Zn and Zr, whereas sulphates, Fe, S, Mo, Mn, Hf and Ge decreased their CP₄ concentrations. OP results from ascorbic acid (AA), glutathione (GSH) and dithiothreitol (DTT) tests evidenced a clear link between specific inorganic components of CP₄ with OP^AA and the organic fraction of OP^GSH and OP^DTT. Correlation analyses were performed for OP indicators and the geochemical patterns of CP₄. These were compared with respirable dust samples from prior studies. They indicate that Fe (r = 0.83), pyrite (r = 0.66) and sulphate minerals (r = 0.42) (tracing acidic species from pyrite oxidation), followed by S (r = 0.50) and ash yield (r = 0.46), and, to a much lesser extent, Ti, anatase, U, Mo, V and Pb, are clearly linked with OP^AA. Moreover, OP^GSH correlation was identified by organic matter, as moisture (r = 0.73), Na (r = 0.56) and B (r = 0.51), and to a lesser extent by the coarse particle size, Ca and carbonate minerals. In addition, Mg (r = 0.70), B (r = 0.47), Na (r = 0.59), Mn, Ba, quartz, particle size and Sr regulate OP^DTT correlations. These became more noticeable when the analysis was done for samples of the same type of coal rank, in this case, bituminous.

First transcriptome profiling of D. melanogaster after development in a deep underground low radiation background laboratory

Natural background radiation is a permanent multicomponent factor. It has an influence on biological organisms, but effects of its deprivation still remain unclear. The aim of our work was to study for the first time responses of D. melanogaster to conditions of the Deep Underground Low-Background Laboratory DULB-4900 (BNO, INR, RAS, Russia) at the transcriptome level by RNA-seq profiling. Overall 77 transcripts demonstrated differential abundance between flies exposed to low and natural background radiation. Enriched biological process functional categories were established for all genes with differential expression. The results showed down-regulation of primary metabolic processes and up-regulation of both the immune system process and the response to stimuli. The comparative analysis of our data and publicly available transcriptome data on D. melanogaster exposed to low and high doses of ionizing radiation did not reveal common DEGs in them. We hypothesize that the observed changes in gene expression can be explained by the influence of the underground conditions in DULB-4900, in particular, by the lack of stimuli. Thus, our study challenges the validity of the LNT model for the region of background radiation doses below a certain level (~16.4 nGy h-1) and the presence of a dose threshold for D. melanogaster.