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Cadmium (Cd) is an environmental pollutant that damages various tissues. Cd may cause a depletion of iron stores and subsequently an iron deficiency state in the liver. However, the molecular mechanism of decreased iron accumulation in the liver induced by long-term exposure to Cd is unknown. In this study, we investigated the hepatic accumulation of iron and the proximal duodenal expression of the genes involved in iron transport using mice chronically exposed to Cd. Five-week-old female C57BL/6J mice were fed a diet containing 300 ppm Cd for 12, 15, 19 and 21 months. The iron concentration in the liver was markedly decreased by Cd. Among iron-transport-related genes in the proximal duodenum, the gene expression of HCP1 and Cybrd1 was significantly decreased by Cd. HCP1 is an influx transporter of heme iron. Cybrd1 is a reductase that allows non-heme iron to enter cells. The expression of iron-transport-related genes on the duodenal basolateral membrane side was hardly altered by Cd. These results suggest that long-term exposure to Cd suppresses the expression of HCP1 and Cybrd1 in the proximal duodenum, resulting in reduced iron absorption and iron accumulation in the liver. [ABSTRACT FROM AUTHOR]

Biofouling is a significant means for introducing non-indigenous marine species internationally, which can alter habitats and disturb marine ecosystems. This study estimated the flux of ships' wetted surface area (WSA) to Korea in 2020 to assess the risks of biological invasion via biofouling on ships' hulls. The annual total WSA flux entering Korea was estimated to be 418.26 km2, with short-stay vessels (<3 weeks) contributing to 99.7% of the total WSA flux. Busan and Ulsan ports were identified as the main sources of high-risk flux, with container ships being a major vector in Busan and tankers in Ulsan. Gwangyang port had the third-highest total WSA flux, with nearly half of the flux driven from coastwise voyages, making it particularly vulnerable to the spread of hull fouling organisms. These findings could help enhance the management and inspection of hull fouling organisms in Korea. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic heavy metal that is widely present in the environment. Renal proximal tubule disorder is the main symptom of Cd chronic poisoning. Our previous study demonstrated that Cd inhibits the total activities of peroxisome proliferator-activated receptor (PPAR) transcription factors in human and rat proximal tubular cells. In this study, we investigated the involvement of PPAR in Cd renal toxicity using the HK-2 human proximal tubular cell line. Among PPAR isoform genes, only PPARD knockdown significantly showed resistance to Cd toxicity in HK-2 cells. The transcriptional activity of PPARδ was decreased not only by PPARD knockdown but also by Cd treatment. DNA microarray analysis showed that PPARD knockdown changed the expression of apoptosis-related genes in HK-2 cells. PPARD knockdown decreased apoptosis signals and caspase-3 activity induced by Cd treatment. PPARD knockdown did not affect the intracellular Cd level after Cd treatment. These results suggest that PPARδ plays a critical role in the modification of susceptibility to Cd renal toxicity and that the apoptosis pathway may be involved in PPARδ-related Cd toxicity. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are promising candidates for the replacement of lithium-ion batteries (LIBs) because of sodium's abundant reserves and the lower cost of sodium compared to lithium. This is a topic of interest for developing novel anodes with high storage capacity. Owing to their low cost, high stability, and conductivity, carbon-based materials have been studied extensively. However, sp2-C based carbon materials have low-rate capacities. Intensive density functional theory calculations have been implemented to explore the applicability of α, β, and γ graphyne nanotubes (αGyNTs, βGyNTs, and γGyNTs, respectively) as SIB anodes. Results suggest that (3, 0)-αGyNT, (2, 2)-βGyNT, and (4, 0)-γGyNT have, respectively, maximum Na storage capacities of 1535, 1302, and 1001 mAh/g, which exceeds the largest reported value of carbon materials (N-doped graphene foams with 852.6 mAh/g capacity). It was determined that αGyNTs have the largest storage capacity of the three types because they possess the largest specific surface area. Moreover, the larger pores of αGyNTs and βGyNTs allow easier diffusion and penetration of Na atoms compared to those of γGyNTs, which could result in better rate capacity. [ABSTRACT FROM AUTHOR]

Efforts to reduce the toxic effects of microplastics (MPs) on the environment have increased globally in recent years. However, the existing models used for the simulation of contaminant transport in groundwater are meant for dissolved substances, which is not suitable for studying MPs. Therefore, in this study, the transport of MPs in a saturated porous medium was modeled by establishing governing equations. Simulations were performed using the finite element method to examine the effects of the parameters of the governing equations on the transport of MPs. The results suggest that it is necessary to reduce the diffusivity of MPs and increase the water flow velocity, porosity, and first-order attachment coefficient to effectively contain this environmental hazard. From the simulation results, it can be derived that a combination of low diffusivity, fast water flow velocity, and high soil porosity may reduce the amount of MPs that are leaked into groundwater environments. The modeling and simulations performed in this study provide a clear understanding of the transport phenomena of MPs with applications in combating water pollution. [ABSTRACT FROM AUTHOR]

The effects of the unpredictability of the flow system in a karst area, with respect to bacterial communities in the aquatic environment, were evaluated. Bacterial communities from two different types of flow conditions (spring and sinkhole) were characterized and compared in the karst area. Proteobacteria, Bacteroidetes, and Verrucomicrobia were the major phyla present in the sampled spring and sinkhole waters. The water samples from the spring points were heavily loaded with Actinobacteria, especially Firmicutes, which accounted for 4.3% of the bacterial content. Furthermore, Actinobacteria were prevalent in some water samples, serving as indicators of the effects of seawater inundation. The richness and diversity of bacterial species were evaluated at the spring and sinkhole water points. The spring waters showed a higher bacterial richness and diversity compared to the sinkhole waters. Our results provide valuable information for the evaluation and investigation of microbial compositions in karst areas, which are characterized by heterogeneous hydrological conditions. The microbial species in karst areas are already exposed to changing hydrogeological conditions, and are likely to be confronted with future changes; thus, their spatiotemporal variations reflect the shifting baselines of physicochemical and ecosystem processes. [ABSTRACT FROM AUTHOR]

Hundreds of millions of people around the world have been affected by Type 2 diabetes (T2D) which is a metabolic disorder. Clinical research has revealed T2D as a possible risk factor for Alzheimer's disease (AD) development (and vice versa). Amyloid-β (Aβ) and human islet amyloid polypeptide are the main pathological species in AD and T2D, respectively. However, the mechanisms by which these two amyloidogenic peptides co-aggregate are largely uninvestigated. Herein, for the first time, we present the cross-seeding between Amylin1-37 and Aβ40 considering the particular effect of the histidine tautomerism at atomic resolution applying the all-atom molecular dynamics (MD) simulations for heterodimeric complexes. The results via random seed MD simulations indicated that the Aβ40(δδδ) isomer in cross-talking with Islet(ε) and Islet(δ) isomers could retain or increase the β-sheet content in its structure that may make it more prone to further aggregation and exhibit higher toxicity. The other tautomeric isomers which initially did not have a β-sheet structure in their monomeric forms did not show any generated β-sheet, except for one seed of the Islet(ε) and Aβ40(εεε) heterodimers complex that displayed a small amount of formed β-sheet. This computational research may provide a different point of view to examine all possible parameters that may contribute to the development of AD and T2D and provide a better understanding of the pathological link between these two severe diseases. [ABSTRACT FROM AUTHOR]

Karst regions cover approximately 10% of the Korean Peninsula and are highly vulnerable to contamination. In this study, five field surveys were conducted between 2017 and 2019 to examine the monthly and seasonal changes in the hydro-environment of a characteristic karst region in Samchoek, South Korea. During the surveys, a total of 24 surface water samples were collected and analyzed for field water quality parameters, major and minor ions, and stable isotopes. The results indicate that the water quality in the study area is significantly affected by precipitation. Overall, the water was classified as a Ca-Mg-HCO3 type, and correlation analysis of the major ions detected in the water samples indicates that the inflow of nitrate to the surface water originated from agricultural activities in the region. Furthermore, variations caused by climate were verified using the relationships between the various ions. In addition, high precipitation rates during the rainy season cause the active exchange of surface material, which was verified using stable isotope outliers. The results provide a scientific basis for studying the connectivity of water systems in complex karst hydrogeological regions and can aid future sustainable management of water resources in these regions. [ABSTRACT FROM AUTHOR]

It has been recognized that p-Coumaric acid (p-CA) has protective effects as an antioxidant, anti-inflammatory agent. A sensitive and efficient Liquid Chromatography-Mass Spectrometry (LC-MS) method for maximum determination of p-CA in human plasma has been established using Ultra-performance liquid Chromatography-tandem mass Spectrometry (UPLC-MS/MS). This study provides the developed analysis of p-CA extracted from Bambusae Caulis in Taeniam (BC) to examine the improvement of the treatment p-CA, IGF-1 and Osteocalcin level in human children which are important factors on the growth of children's height through Pharmacokinetics/Pharmacodynamics (PK/PD) model. p-CA and internal standard in a plasma sample were detected by the Multiple Reaction Monitoring (MRM) scan mode with positive ion detection. The sample participating in the study was made of 34 subjects (placebo = 18, treatment = 16). The subjects were enrolled to be randomized to the control group and BC group. Randomized subjects took tested treatment twice a day, three capsules with oral administration (258 mg/capsule) each time after a meal. Standard calibration curves (reproducibility) were constructed and the lower limit of quantitation (LLOQ) for p-CA was found to be 0.2 ng/mL on injection of the sample into the UPLC-MS/MS system. Accuracy and precision were evaluated and the intra-accuracy was 99.2–103.8% with precision of 1.0–5.6% and inter-accuracy was 99.6–108.4% and precision of 1.3–6.4% for p-CA. The method has been successfully applied to PK/PD studies of p-CA in human plasma. The p-CA, BC in Taeniam extract increased the level of IGF-1 and Osteocalcin, and changed the height from baseline, which suggested that the p-CA could play an important role in longitudinal bone growth. Therefore, the p-CA extracted from BC in Taeniam might be a good alternative medicine to growth hormone (GH) therapy. [ABSTRACT FROM AUTHOR]

Factors controlling the spatial distribution and temporal trend of groundwater quality at a national scale are important to investigate for sustaining livelihood and ecological balance. This study evaluated groundwater quality data for 12 parameters (n = 6405 for each parameter), collected from 97 groundwater monitoring stations (=289 monitoring wells) for ten years. Spatial distribution of groundwater quality parameters varied through the regional scale. Six parameters: T, EC, Ca2+, Mg2+, HCO3−, and Cl− were having dominant increasing trend, remaining pH, Eh, Na+, K+, SO42−, and NO3− showed a dominant decreasing trend over time. Among land use types, the upland fields had the highest mean of groundwater NO3− (22.2 mg/L), confirming plenty of application of fertilizers (5–10 kg/a more than standard) to upland fields. Means of groundwater Cl− and Na+ (705.3 and 298.4 mg/L, respectively) in the residential areas are greater than those in other land use types by 408–685.9, 154.3–274.2 mg/L, respectively. Agricultural activities were the main controlling factor of groundwater NO3− contamination in rural areas, domestic activities were responsible for groundwater Cl− and Na+ in urban areas, and seawater intrusion was controlling groundwater Cl− in coastal areas (within 10 km from sea). Groundwater hydrochemistry was controlled by the mechanism of geogenic rock and evaporation dominance. The rock dominance mechanism indicated that groundwater was interacting with rocks and resulted in groundwater chemistry. The findings of this study showed that groundwater was mainly contaminated by anthropogenic factors in some rural and residential areas. Effective measures by government authorities are needed to improve the groundwater quality. [ABSTRACT FROM AUTHOR]

This study analyzed the hydrochemical characteristics and microbial communities of karst water in Samcheok, Korea, and compared water quality results to identify the seasonal characteristics and hydrogeological connectivity of the study areas of Hamaengbang-ri, Gyogok-ri, Yeosam-ri, and the downtown area of Samcheok. Field survey and water quality analysis were performed in July 2019, February 2020, and April 2020. Hydrochemical analysis of karst water (groundwater and surface water) showed that most samples were comprised of Ca-HCO3 and that water–rock interactions were a dominant factor compared to precipitation and evaporation (crystallization). For seasonal characteristics, water–rock interactions appeared more active in the dry season than in the rainy season. Calcite weathering was dominant in the dry season, whereas dolomite weathering dominated the rainy season. Moreover, the saturation indexes for the dry and rainy seasons were less than and greater than 0, respectively, corresponding to an unsaturation (oversaturation) state; thus, white precipitate distributed in the study areas was deposited in the rainy season. Finally, as a result of analyzing the hydraulic characteristics between regions, hydrogeological similarities were identified between Hamaengbang-ri and Yeosam-ri, and between Gyogok-ri and downtown Samcheok, which suggested hydrogeological connectivity between each of the pairs. [ABSTRACT FROM AUTHOR]

MPs are a new type of pollutant in the groundwater environment. In South Korea, as MPs were detected in tap water in 2017, investigations into the distribution of MPs in industrial and sewage treatment facility discharge water were initiated [[22]]. Groundwater contamination by MPs is of particular concern because the HZ, waterfront areas near wastewater treatment facilities, and karst areas have highly vulnerable hydrogeological properties for maintaining and managing groundwater resources (Figure 1). [Extracted from the article]

Under changing climate, increasing groundwater use has risen the concern for groundwater quality variations over recent years, to maintain a healthy ecosystem. The objectives were to identify trend of temporal variations in groundwater quality and its suitability for different uses in Republic of Korea. Water quality data were collected from 198 monitoring stations of Groundwater Quality Monitoring Network (GQMN), annually for the period of ten years (2008–2017). Non-parametric trend analysis of a Mann–Kendall test and Theil–Sen's slope was done on groundwater physico-chemical data of ten years. Groundwater suitability evaluation was done for use in main sectors including domestic (drinking) and agriculture (irrigation). For drinking suitability analysis, results were compared with World Health Organization (WHO) and Korean Ministry of Environment (KME) established guidelines. For irrigation suitability evaluation, electrical conductivity (EC), Sodium Adsorption Ratio (SAR), percent of Na+, Residual Sodium Carbonate (RSC), US Salinity Laboratory (USSL), and Wilcox diagram were used. Most significantly, water type belongs to Ca-HCO3 and Ca-SO4 types, but a small proportion belongs to Na-CO3 and Na-Cl types. Approximately, 96% and 93% of groundwater samples are suitable for drinking, based on WHO and KME guidelines, respectively. Around 98% and 83% of groundwater samples are in suitable range for irrigation use, based on USSL and Wilcox diagrams, respectively. [ABSTRACT FROM AUTHOR]

Groundwater samples were collected from the tubular wells of a groundwater heat pump (GWHP), and the psychrophilic, mesophilic, and thermophilic bacteria inhabiting the collected groundwater were cultured and isolated. Using the isolated bacteria, we analyzed temperature-dependent changes in autochthonous bacteria based on the operation of the GWHP. Microbial culture identified eight species of bacteria: five species of thermophilic bacteria (Anoxybacillus tepidamans, Bacillus oceanisediminis, Deinococcus geothermalis, Effusibacillus pohliae, and Vulcaniibacterium thermophilum), one species of mesophilic bacteria (Lysobacter mobilis), and two species of psychrophilic bacteria (Paenibacillus elgii and Paenibacillus lautus). The results indicated A. tepidamans as the most dominant thermophilic bacterium in the study area. Notably, the Anoxybacillus genus was previous reported as a microorganism capable of creating deposits that clog above-ground wells and filters at geothermal power plants. Additionally, we found that on-site operation of the GWHP had a greater influence on the activity of thermophilic bacteria than on psychrophilic bacteria among autochthonous bacteria. These findings suggested that study of cultures of thermophilic bacteria might contribute to understanding the bio-clogging phenomena mediated by A. tepidamans in regard to GWHP-related thermal efficiency. [ABSTRACT FROM AUTHOR]

Mercury compounds are known to cause central nervous system disorders; however the detailed molecular mechanisms of their actions remain unclear. Methylmercury increases the expression of several chemokine genes, specifically in the brain, while metallothionein-III (MT-III) has a protective role against various brain diseases. In this study, we investigated the involvement of MT-III in chemokine gene expression changes in response to methylmercury and mercury vapor in the cerebrum and cerebellum of wild-type mice and MT-III null mice. No difference in mercury concentration was observed between the wild-type mice and MT-III null mice in any brain tissue examined. The expression of Ccl3 in the cerebrum and of Cxcl10 in the cerebellum was increased by methylmercury in the MT-III null but not the wild-type mice. The expression of Ccl7 in the cerebellum was increased by mercury vapor in the MT-III null mice but not the wild-type mice. However, the expression of Ccl12 and Cxcl12 was increased in the cerebrum by methylmercury only in the wild-type mice and the expression of Ccl3 in the cerebellum was increased by mercury vapor only in the wild-type mice. These results indicate that MT-III does not affect mercury accumulation in the brain, but that it affects the expression of some chemokine genes in response to mercury compounds. [ABSTRACT FROM AUTHOR]

Homeobox protein B13 (HOXB13), a transcription factor, is related to methylmercury toxicity; however, the downstream factors involved in enhancing methylmercury toxicity remain unknown. We performed microarray analysis to search for downstream factors whose expression is induced by methylmercury via HOXB13 in human embryonic kidney cells (HEK293), which are useful model cells for analyzing molecular mechanisms. Methylmercury induced the expression of oncostatin M (OSM), a cytokine of the interleukin-6 family, and this was markedly suppressed by HOXB13 knockdown. OSM knockdown also conferred resistance to methylmercury in HEK293 cells, and no added methylmercury resistance was observed when both HOXB13 and OSM were knocked down. Binding of HOXB13 to the OSM gene promoter was increased by methylmercury, indicating the involvement of HOXB13 in the enhancement of its toxicity. Because addition of recombinant OSM to the medium enhanced methylmercury toxicity in OSM-knockdown cells, extracellularly released OSM was believed to enhance methylmercury toxicity via membrane receptors. We discovered tumor necrosis factor receptor (TNF) receptor 3 (TNFR3) to be a potential candidate involved in the enhancement of methylmercury toxicity by OSM. This toxicity mechanism was also confirmed in mouse neuronal stem cells. We report, for the first time, that HOXB13 is involved in enhancement of methylmercury toxicity via OSM-expression induction and that the synthesized OSM causes cell death by binding to TNFR3 extracellularly.

The study of medicinal plants for treatment of periodontitis is of great value to establish their efficacy as sources of new antimicrobial drugs. Five hundred and fifty eight Korean local plant extracts were screened for antibacterial activity against representative periodontopathic bacteria such as Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum. Among the various medicinal plants, the alcohol extract of Pittosporum tobira, which significantly exhibited antibacterial effect for all tested strains, showed the highest activity in the antimicrobial assays. NMR analyses revealed that R1-barrigenol, a triterpene sapogenin, was the most effective compound in P. tobira. These results demonstrated that P. tobira possesses antimicrobial properties and would be beneficial for the prevention and treatment of periodontitis.