• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.61-68
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• 2013

This paper presents an experimental results on the environmental characteristics of waste tire. Experimental program includes a set of laboratory leaching tests and field pilot test for leachate analysis. Laboratory tests were conducted to illustrate how properties such as TOC, pH, turbidity and Zn change with tire sizes and drain conditions. In field pilot test, water samples were collected form a drainage system installed below the tire-reinforced retaining wall and analyzed for chemical quality. Laboratory leaching tests performed on various particle sizes of waste tire indicated that as tire size is increased, the concentration of leachate is decreased. In continuous flow column tests, the concentration of leachate decreased with the number of exposure periods or pore volumes flushed through the waste tire. However, during pause flow column tests, the concentration of leachates were increased with time. Field monitoring of effluent indicated that no significant adverse effects on ground water quality had occurred over a period of 12 months.

• Journal of Periodontal and Implant Science
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• v.45 no.3
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• pp.82-93
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• 2015

Purpose: This retrospective study evaluated the relationship between the timing of peri-implantitis diagnosis and marginal bone level after a 5-year follow-up of non-surgical peri-implantitis treatment. Methods: Thirty-three patients (69 implants) were given peri-implantitis diagnosis in 2008-2009 in Seoul National University Bundang Hospital. Among them, 31 implants from 16 patients were included in this study. They were treated non-surgically in this hospital, and came for regular maintenance visits for at least 5 years after peri-implantitis treatment. Radiographic marginal bone levels at each interval were measured and statistical analysis was performed. Results: Timing of peri-implantitis was one of the significant factors affecting initial bone loss and total bone loss not additional bone after peri-implantitis diagnosis. Patients with cardiovascular disease and diabetic mellitus were positively influenced on both initial bone loss and total bone loss. Patients who needed periodontal treatment after implant placement showed a negative effect on bone loss compared to those who needed periodontal treatment before implant placement during entire periods. Implant location also significantly influenced on amounts of bone loss. Mandibular implants showed less bone loss than maxillary implants. Among surgical factors, combined use of autogenous and xenogenic bone graft materials showed a negative effect on bone loss compared to autogenous bone graft materials. Use of membrane negatively affected on initial bone loss but positively on additional bone loss and total bone loss. Thread exposure showed positive effects on initial bone loss and total bone loss. Conclusions: Early peri-implantitis diagnosis led to early non-surgical intervention for peri-implantitis treatment, which resulted in the maintenance of the bone level as well as preservation of the implant.

• Journal of Periodontal and Implant Science
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• v.39 no.2
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• pp.167-176
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• 2009

Purpose: The purpose of this study is to histologically and histomorphometrically evaluate the effect of PLGA on bone regeneration compared with bone graft material. Methods: The experimental study was conducted in 10 rabbits with 2 different healing periods of 2 and 4 weeks. Following surgical exposure of the calvarium, 4 circular bone defects with a diameter of 4.6mm were formed. Rabbits were divided into control group, test groups I, and II. 10 defects assigned to the test group Ⅰ were grafted with Nu-oss and other 10 defects assigned to the test group II were grafted with PLGA. The rest of the defects were in the negative control group. At 2nd and 4th week after surgery, 10 rabbits were sacrificed through intracardiac perfusion and then specimens were obtained. Histological analysis was performed following staining with trichorme and transversal sectioning of the calvarial bone. Results: A group which used PLGA showed tissue reactions characterized by severe inflammation, rather than distinctive new bone formation. Conclusions: The present experimental investigations have failed to prove any beneficial effects of PLGA. PLGA used in this study exhibited foreign body reactions and a less favorable pattern of new bone formation in comparison to control group. Conclusion: PLGA did not function as scaffold. Further investigations of many types of micro PLGA that could improve its potential in GBR procedures are needed.

• Tuberculosis and Respiratory Diseases
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• v.73 no.2
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• pp.84-92
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• 2012

Background: Asian dust storms can be transported across eastern Asia. In vitro, Asian dust particle-induced inflammation and enhancement of the allergic reaction have been observed. However, the fibrotic effects of Asian dust particles are not clear. Production of transforming growth factor ${\beta}_1$ (TGF-${\beta}_1$) and fibronectin were investigated in the bronchial epithelial cells after exposure to Asian dust particulate matter (AD-PM10). Methods: During Asian dust storm periods, air samples were collected. The bronchial epithelial cells were exposed to AD-PM10 with and without the antioxidant, N-acetyl-L-cysteine (NAC). Then TGF-${\beta}_1$ and fibronectin were detected by Western blotting. The reactive oxygen species (ROS) was detected by the measurement of dicholorodihydrofluorescin (DCF), using a FACScan, and visualized by a confocal microscopy. Results: The expression of TGF-${\beta}_1$, fibronectin and ROS was high after being exposed to AD-PM10, compared to the control. NAC attenuated both TGF-${\beta}_1$ and fibronectin expression in the AD-PM10-exposed the bronchial epithelial cells. Conclusion: AD-PM10 may have fibrotic potential in the bronchial epithelial cells and the possible mechanism is AD-PM10-induced intracellular ROS.

• Environmental and Resource Economics Review
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• v.26 no.3
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• pp.287-317
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• 2017

Asbestos has been actively used for various places. Since it was designated as the first grade carcinogen in the 1970s, strict regulations on using asbestos has been implemented globally. Considering long-term latent periods between asbestos exposure and environmental diseases, we analyze the time lag between asbestos consumption and the incidence of mesothelioma in Korea and estimate the long-run relationship. In addition, we conduct a comparative analysis on the effectiveness of asbestos regulations in the United Kingdom and the United States, which have accumulated long-term time-series observations. The latent period analysis indicates that the consumption of asbestos and the incidence of the disease are highly correlated in all three countries, being long-term lags of more than 30 years. Also, we find a long-run equilibrium relationship between asbestos consumption and the incidence of mesothelioma in the presence of long-term lags between the variables in all three countries. Furthermore, using a distributed lag model, asbestos consumption has statistically significant positive effects on mesothelioma with a long-term lag.

• Journal of Periodontal and Implant Science
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• v.45 no.1
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• pp.23-29
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• 2015

Purpose: This study was conducted to compare the cumulative survival rates (CSRs) and the incidence of postloading complications (PLCs) between a bone-level internal connection system (ICS-BL) and an external connection system (ECS). Methods: The medical records of patients treated with either a ICS-BL or ECS between 2007 and 2010 at Asan Medical Center were reviewed. PLCs were divided into two categories: biological and technical. Biological complications included >4 mm of probing pocket depth, thread exposure in radiographs, and soft tissue complications, whereas technical complications included chipping of the veneering material, fracture of the implant, fracture of the crown, loosening or fracture of the abutment or screw, loss of retention, and loss of access hole filling material. CSRs were determined by a life-table analysis and compared using the log-rank chi-square test. The incidence of PLC was compared with the Pearson chi-squared test. Results: A total of 2,651 implants in 1,074 patients (1,167 ICS-BLs in 551 patients and 1,484 ECSs in 523 patients) were analyzed. The average observation periods were 3.4 years for the ICS-BLs and 3.1 years for the ECSs. The six-year CSR of all implants was 96.1% (94.9% for the ICS-BLs and 97.1% for the ECSs, P=0.619). Soft tissue complications were more frequent with the ECSs (P=0.005) and loosening or fracture of the abutment or screw occurred more frequently with the ICS-BLs (P<0.001). Conclusions: Within the limitations of this study, the ICS-BL was more prone to technical complications while the ECS was more vulnerable to biological complications.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1263-1268
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• 2018

Three different ice core samples from Antarctica were analyzed to identify activity concentrations of radioactive isotopes. Tracking migration of radioactive isotopes to Antarctica can provide a key clue to understand global environmental changes caused by radiation exposures because the Antarctic ice cores can preserve unique characteristics of various environmental conditions. We are particularly interested in the $^{137}Cs$ nucleus, because it is closely related to radiation exposure from nuclear power plant accidents and nuclear bomb tests. With its half life of $30.17{\pm}0.03$ years, $^{137}Cs$ can also be used to assess the age of sedimentation occurring after around the year 1945. We selected three ice core samples, called Tarn8, Styx27, and H25, from different time periods; the Tarn8 sample is known to be from earlier than ~ 1000 AD, the Styx27 sample is approximately from the year 1945, and the H25 sample is from the year 2012. Radioactive isotope measurements of the ice core samples were performed using a 100% HPGe detector at Cheongpyeong Underground Radiation Laboratory (CURL). We measured the activity of $^{137}Cs$ in the H25 sample to be $0.98{\pm}0.82mBq/kg$. Although the activity has a large uncertainty mainly due to the limited sample quantity, the $^{137}Cs$ isotopes in the Antarctic ice core were measured for the first time in Korea.

• Journal of Ginseng Research
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• v.43 no.4
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• pp.654-665
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• 2019

Background: Panax ginseng Meyer has widely been used as a traditional herbal medicine because of its diverse health benefits. Amounts of ginseng compounds, mainly ginsenosides, vary according to seasons, varieties, geographical regions, and age of ginseng plants. However, no study has comprehensively determined perturbations of various metabolites in ginseng plants including roots and leaves as they grow. Methods: Nuclear magnetic resonance ($^1H$ NMR)-based metabolomics was applied to better understand the metabolic physiology of ginseng plants and their association with climate through global profiling of ginseng metabolites in roots and leaves during whole growing periods. Results: The results revealed that all metabolites including carbohydrates, amino acids, organic acids, and ginsenosides in ginseng roots and leaves were clearly dependent on growing seasons from March to October. In particular, ginsenosides, arginine, sterols, fatty acids, and uracil diphosphate glucose-sugars were markedly synthesized from March until May, together with accelerated sucrose catabolism, possibly associated with climatic changes such as sun exposure time and rainfall. Conclusion: This study highlights the intrinsic metabolic characteristics of ginseng plants and their associations with climate changes during their growth. It provides important information not only for better understanding of the metabolic phenotype of ginseng but also for quality improvement of ginseng through modification of cultivation.

• Journal of Embryo Transfer
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• v.33 no.4
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• pp.287-296
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• 2018

Ganglioside GM3 is known as an inhibition factor of cell differentiation and proliferation via inhibition of epidermal growth factor receptor (EGFR) phosphorylation. Our previous study showed that the exogenous ganglioside GM3 reduced the meiotic maturation of porcine oocytes and induced apoptosis at 44 h of in vitro maturation (IVM). However, the role of ganglioside GM3 in the relationship between EGFR signaling and apoptosis during porcine oocyte maturation has not yet been studied. First, porcine cumulus-oocyte complexes (COCs) were cultured in the NCSU-23 medium with exogenous ganglioside GM3 according to maturation periods (non-treated, only IVM I: 0 - 22 h, only IVM II: 22 - 44 h and IVM I & II: 0 - 44 h). We confirmed that the proportion of germinal vesicle breakdown (GVBD) increased significantly in the IVM I treated group than in the control group. We also confirmed that the meiotic maturation until M II stage and polar body formation decreased significantly in the only IVM I treated group. Cumulus cell expansion and mRNA levels of the expansion-related factors (HAS2, TNFAIP6 and PTX3) decreased significantly in the IVM I treated group than in the control group. Protein levels of EGFR, p-EGFR, ERK1/2, and p-ERK1/2 decreased significantly in the GM3-treated groups, during the IVM I period. In addition, cellular apoptosis, determined using TUNEL assay, and protein levels of Cleaved caspase 3, were increased significantly in the GM3-treated COCs during the IVM I period. Based on these results, ganglioside GM3 exposure of porcine COCs during the IVM I period reduced meiotic maturation and cumulus cell expansion via inhibition of EGFR activity in pigs.

• Biomolecules & Therapeutics
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• v.30 no.4
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• pp.320-327
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• 2022

Neurodevelopmental disorders are complex conditions that pose difficulty in the modulation of proper motor, sensory and cognitive function due to dysregulated neuronal development. Previous studies have reported that an imbalance in the excitation/inhibition (E/I) in the brain regulated by glutamatergic and/or GABAergic neurotransmission can cause neurodevelopmental and neuropsychiatric behavioral deficits such as autism spectrum disorder (ASD). NMDA acts as an agonist at the NMDA receptor and imitates the action of the glutamate on that receptor. NMDA however, unlike glutamate, only binds to and regulates the NMDA receptor subtypes and not the other glutamate receptors. This study seeks to determine whether NMDA administration in mice i.e., over-activation of the NMDA system would result in long-lasting behavioral deficits in the adolescent mice. Both gender mice were treated with NMDA or saline at early postnatal developmental period with significant synaptogenesis and synaptic maturation. On postnatal day 28, various behavioral experiments were conducted to assess and identify behavioral characteristics. NMDA-treated mice show social deficits, and repetitive behavior in both gender mice at adolescent periods. However, only the male mice but not female mice showed increased locomotor activity. This study implies that neonatal exposure to NMDA may illicit behavioral features similar to ASD. This study also confirms the validity of the E/I imbalance theory of ASD and that NMDA injection can be used as a pharmacologic model for ASD. Future studies may explore the mechanism behind the gender difference in locomotor activity as well as the human relevance and therapeutic significance of the present findings.