• Tuberculosis and Respiratory Diseases
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• v.48 no.4
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• pp.478-486
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• 2000

Background : In acute lung injury, alveolar macrophages play a pivotal role in the inflammatory process during the initiation phase and in the reconstruction and fibrosis process during the later phase. Recently, it has been proven that alveolar macrophages are constituted by morphologically, biochemically and immunologically heterogenous cell subpopulations. The possibility of alterations to these characteristics of the alveolar macrophage population during lung disease has been raised. To investigate such a possibility a hyperoxic rat lung model was made to check the distributional and morphological changes of rat alveolar macrophage subpopulation in acute hyperoxic lung injury. Method : Alveolar macrophage were lavaged from normal and hyperoxic lung injury rats and separated by discontinuous gradients of percoll. After cell counts of each density fraction were accessed, the morphomeric analysis of alveolar macrophages was performed on cytocentrifuged preparations by transmission electron micrograph. Result : 1. The total alveolar macrophage cell count significantly increased up to 24 hours after hyperoxic challenge (normal control group $171.6{\pm}24.1{\times}10^5$, 12 hour group $194.8{\pm}17.9{\times}10^5$, 24 hour group $207.6{\pm}27.1{\times}10^5$, p<0.05). oHoHH However the 48 hour group ($200.0{\pm}77.8{\times}10^5$) did not show a significant difference. 2. Alveolar septal thickness significantly increased up to 24 hours after hyperoxic challenge(normal control group $0.7{\pm}0.2{\mu}m$, 12 hour group $1.5{\pm}0.4{\mu}m$, 24 hour group $2.3{\pm}0.4{\mu}m$, p<0.05). However the 48 hour group did not show further change ($2.5{\pm}0.4{\mu}m$). Number of interstitial macrophage markedly increased at 24 hour group. 3. Hypodense fraction(fraction 1 and fraction 2) of alveolar macrophage showed a significant increase following hyperoxic challenge ($\beta=0.379$.$\beta=0.694$. p<0.05) ; however, fraction 3 was rather decreased following the hyperoxic challenge($\beta=0.815$. p<0.05), and fraction 4 showed an irregular pattern. 4. Electron microscopic observation of alveolar macrophage from each fraction revealed considerable morphologic heterogeneity. Cells of the most dense subfraction(fraction 4) were small, round, and typically highly ruffled with small membrane pseudopods. Cells of the least dense fraction (fraction 1) were large and showed irregular eccentric nucleus and high number of heterogenous inclusions. Conclusion : In conclusion, these results suggest that specific hypodense alveolar macrophage subpopulation may play a an important role in an acute hyperoxic lung injury model But further study, including biochemical and immunological function of these subpopulations, is needed.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.613-623
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• 2013

This study is purposed to evaluate the airborne asbestos concentrations in life environment surroundings in Seoul. In study, we investigated airborne asbestos concentrations in thirteen subway stations, four monitoring networks and each vicinity roadside, six stream surroundings, four tunnels quarterly and we also investigated relationship between the airborne asbestos concentrations and ambient temperature in monitoring networks and time-based airborne asbestos concentration variability for two typical monitoring networks, two subway stations transferred and used by lots of people through Phase Contrast Microscopy (PCM) and Transmission Electron Microscopy (TEM). The airborne asbestos concentrations by PCM for 4 objects of study were less than the detection limit (7 fiber/$mm^2$) in 111 (50%) out of 223 samples. The highest concentration was 0.0130 f/cc. But additional TEM analysis result for samples exceeding the guideline value for indoor air quality (0.01 f/cc) proposed by the Ministry of Environment (Korea), no asbestos was detected. Similarly TEM analysis result for 124 samples, no asbestos was detected. The average airborne asbestos concentrations by PCM in subway stations, monitoring networks, streams and tunnels were $0.0041{\pm}0.0027$ f/cc, $0.0015{\pm}0.0011$ f/cc, $0.0024{\pm}0.0012$ f/cc and $0.0016{\pm}0.0020$ f/cc. All objects of study were satisfied with the guideline value for indoor air quality. The relationship between the airborne asbestos concentrations and ambient temperature in monitoring networks was generally positive correlation (r = 0.660). The higher ambient temperature was and the more transient population was, the airborne asbestos concentrations by time for two subway stations were increased. While the airborne asbestos concentrations for two monitoring networks showed no variation pattern according to time.

• Applied Microscopy
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• v.41 no.4
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• pp.277-284
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• 2011

This study was conducted to determine the antiseptic effect of stabilized chlorine dioxide (S-$ClO_2$) on muscle tissue of rats. Skeletal muscle of 8-week old Sprague-Dawley rats was used. Light and transmission electron microscopic findings were observed in the control group, which was not treated with stabilized chlorine dioxide, and in the experimental group, which was treated with a stabilized chlorine dioxide powder in aqueous solution. According to the LM and TEM observations, the day 1 control group showed the initiation of endomysium collapse resulting in an unclear boundary of muscle fibers, and partial collapse of the mitochondrial membranes. All endomysium had collapsed, and bacteria were observed among muscle fibers in the day 2 and later groups. Shapes of muscles were not distinguishable in day 3 or later groups. In contrast, the day 1 and 3 experimental groups revealed detailed structure of typical muscles, but partial collapse of the mitochondrial membranes was observed in the day 3 and later groups. Subsequently, connective tissues collapsed and structures in the shape of concentric circles were observed. In summary, the day 1 control group showed the initial collapse of tissues, and shapes were not distinguishable in the day 3 and later groups because most of the tissues had collapsed. In contrast, the day 3 experimental group showed partial collapse, but the overall shapes of muscles were maintained as time went on, confirming the antiseptic effect of stabilized chlorine dioxide on muscles.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.345-350
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• 2012

To investigate the exposure and health risk assessment for the residents near the D-asbestos mine in Chungbuk, Korea. We analyzed asbestos in the 20 ambient air and 23 activity based samples near the mine. The airborne sample results are showed that 8 of 20 samples ranged between 0.0025 to 0.0029 f/cc (fiber per cubic centimeter) and the others were below the detection limit by phase contrast microscopy (PCM). In addition, asbestos fibers were under the detection limit or not being by transmission electron microscopy (TEM). Based on interview and survey targeting the local residents, we made the activity based sampling (ABS) scenarios fit to the conditions of field. At the same time, we calculated the excess lifetime cancer risk (ELCR) of these ABS scenarios according to the ELCR average value and 95% upper confidence limit (UCL). At the case of weed whacking, soil digging and sweeping yard scenario, 95% UCL of ELCR exceeded the $1{\times}10^{-4}$, acceptable risk range for exposure. Based on our study results, it is necessary safety measures such as risk communication, abatement or management of naturally occurring asbestos (NOA).

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.120-123
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• 2007

The typical double-barrier magnetic tunnel junction (DMTJ) structure examined in this paper consists of a Ta 45/Ru 9.5/IrMn 10/CoFe7/$AlO_x$/free layer/AlO/CoFe 7/IrMn 10/Ru 60 (nm). The free layer consists of an $Ni_{16}Fe_{62}Si_8B_{14}$ 7 nm, $Co_{90}Fe_{10}$ (fcc) 7 nm, or CoFe $t_1$/NiFeSiB $t_2$/CoFe $t_1$ layer in which the thicknesses $t_1$ and $t_2$ are varied. The DMTJ with an NiFeSiB-free layer had a tunneling magnetoresistance (TMR) of 28%, an area-resistance product (RA) of $86\;k{\Omega}{\mu}m^2$, a coercivity ($H_c$) of 11 Oe, and an interlayer coupling field ($H_i$) of 20 Oe. To improve the TMR ratio and RA, a DMTJ comprising an amorphous NiFeSiB layer that could partially substitute for the CoFe free layer was investigated. This hybrid DMTJ had a TMR of 30%, an RA of $68\;k{\Omega}{\mu}m^2$, and a of 11 Oe, but an increased of 37 Oe. We confirmed by atomic force microscopy and transmission electron microscopy that increased as the thickness of NiFeSiB decreased. When the amorphous NiFeSiB layer was thick, it was effective in retarding the columnar growth which usually induces a wavy interface. However, if the NiFeSiB layer was thin, the roughness was increased and became large because of the magnetostatic $N{\acute{e}}el$ coupling.

• Journal of Ginseng Research
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• v.47 no.3
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• pp.408-419
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• 2023

Background: Ginsenoside compound K (CK), the main active metabolite in Panax ginseng, has shown good safety and bioavailability in clinical trials and exerts neuroprotective effects in cerebral ischemic stroke. However, its potential role in the prevention of cerebral ischemia/reperfusion (I/R) injury remains unclear. Our study aimed to investigate the molecular mechanism of ginsenoside CK against cerebral I/R injury. Methods: We used a combination of in vitro and in vivo models, including oxygen and glucose deprivation/reperfusion induced PC12 cell model and middle cerebral artery occlusion/reperfusion induced rat model, to mimic I/R injury. Intracellular oxygen consumption and extracellular acidification rate were analyzed by Seahorse multifunctional energy metabolism system; ATP production was detected by luciferase method. The number and size of mitochondria were analyzed by transmission electron microscopy and MitoTracker probe combined with confocal laser microscopy. The potential mechanisms of ginsenoside CK on mitochondrial dynamics and bioenergy were evaluated by RNA interference, pharmacological antagonism combined with co-immunoprecipitation analysis and phenotypic analysis. Results: Ginsenoside CK pretreatment could attenuate mitochondrial translocation of DRP1, mitophagy, mitochondrial apoptosis, and neuronal bioenergy imbalance against cerebral I/R injury in both in vitro and in vivo models. Our data also confirmed that ginsenoside CK administration could reduce the binding affinity of Mul1 and Mfn2 to inhibit the ubiquitination and degradation of Mfn2, thereby elevating the protein level of Mfn2 in cerebral I/R injury. Conclusion: These data provide evidence that ginsenoside CK may be a promising therapeutic agent against cerebral I/R injury via Mul1/Mfn2 mediated mitochondrial dynamics and bioenergy.

• Korean Journal of Ichthyology
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• v.3 no.1
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• pp.48-57
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• 1991

Changes of the activities of the hepatic cells of female mud skipper, Boleophthalmus pectinirostris were investigated under transmission electron microscopy. Monthly changes of gonadosomatic index(GSI) and hepatosomatic index(HSI), variations of protein and nucleic acid contents(total RNA and DNA) of the liver tissues with the gonadal development phase were also studied. GSI began to increase from May(the growing stage), reaching the maximum value in late June(the mature stage), and then it began to decrease from late July(the degenerative stage), reaching the lowest value in late September. Monthly variations of HSI were negatively related to GSI. HSI decreased in the summer season when the ovary was getting mature and reached the maximum in mid October when the ovary was degenerating. In June(the mature stage), the female hepatic cells of the liver tissues became large and nuclei were hypertrophic. The amounts of glycogen particles and lipid droplets in the cells gradually decreased, while a number of granular endoplasmic reticulum increased. It was assumed that well-developed granular endoplasmic reticulum binding ribosomes are supposed to play the leading role in protein synthesis and deposition for vitellogenin in the cytoplasm. In July(the spawning period), glycogen particles and lipid droplets gradually increased, and then these substances were still observed in large quantity in August(the degenerative stage). The protein contents of the liver tissues with the gonadal phases of the ovaries were shown the maximum value($4.720{\pm}0.103\;mg/g$) in June, and afterwards gradually decreased being the minimum($3.640{\pm}0.130\;mg/g$) in July, and then gradually increased in August. The mean total RNA contents per gram of the liver tissues appeared the maximum($0.523{\pm}0.040\;mg/g$) in June, and afterwards gradually decreased to the minimum($0.158{\pm}0.006\;mg/g$) in July and slightly increased in August again. From these results, it could be assumed that protein contents were closely related to RNA contents. The mean total DNA contents per weight (gr) of the liver tissues appeared to be similar although there were some monthly fluctuations. The ratio of the mean total RNA/DNA were 0.745 in June, 0.262 in July, 0.341 in August respectively.

• Journal of Ginseng Research
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• v.44 no.3
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• pp.442-452
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• 2020

Backgroud: Sleep deprivation (SD) impairs learning and memory by inhibiting hippocampal functioning at molecular and cellular levels. Abnormal autophagy and apoptosis are closely associated with neurodegeneration in the central nervous system. This study is aimed to explore the alleviative effect and the underlying molecular mechanism of stem-leaf saponins of Panax notoginseng (SLSP) on the abnormal neuronal autophagy and apoptosis in hippocampus of mice with impaired learning and memory induced by SD. Methods: Mouse spatial learning and memory were assessed by Morris water maze test. Neuronal morphological changes were observed by Nissl staining. Autophagosome formation was examined by transmission electron microscopy, immunofluorescent staining, acridine orange staining, and transient transfection of the tf-LC3 plasmid. Apoptotic event was analyzed by flow cytometry after PI/annexin V staining. The expression or activation of autophagy and apoptosis-related proteins were detected by Western blotting assay. Results: SLSP was shown to improve the spatial learning and memory of mice after SD for 48 h, accomanied with restrained excessive autophage and apoptosis, whereas enhanced activation of phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling pathway in hippocampal neurons. Meanwhile, it improved the aberrant autophagy and apoptosis induced by rapamycin and re-activated phosphoinositide 3-kinase/Akt/mammalian target of rapamycin signaling transduction in HT-22 cells, a hippocampal neuronal cell line. Conclusion: SLSP could alleviate cognitive impairment induced by SD, which was achieved probably through suppressing the abnormal autophagy and apoptosis of hippocampal neurons. The findings may contribute to the clinical application of SLSP in the prevention or therapy of neurological disorders associated with SD.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.284-284
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• 2016

Topological insulator (TI) is a bulk-insulating material with topologically protected Dirac surface states in the band gap. In particular, $Bi_2Se_3$ attracted great attention as a model three-dimensional TI due to its simple electronic structure of the surface states in a relatively large band gap (~0.3 eV). However, experimental efforts using $Bi_2Se_3$ have been difficult due to the abundance of structural defects, which frequently results in the bulk conduction being dominant over the surface conduction in transport due to the bulk doping effects of the defect sites. One promising approach in avoiding this problem is to reduce the structural defects by heteroepitaxially grow $Bi_2Se_3$ on a substrate with a compatible lattice structure, while also preventing surface degradation by encapsulating the pristine interface between $Bi_2Se_3$ and the substrate in a clean growth environment. A particularly promising choice of substrate for the heteroepitaxial growth is hexagonal boron nitride (h-BN), which has the same two-dimensional (2D) van der Waals (vdW) layered structure and hexagonal lattice symmetry as $Bi_2Se_3$. Moreover, since h-BN is a dielectric insulator with a large bandgap energy of 5.97 eV and chemically inert surfaces, it is well suited as a substrate for high mobility electronic transport studies of vdW material systems. Here we report the heteroepitaxial growth and characterization of high quality topological insulator $Bi_2Se_3$ thin films prepared on h-BN layers. Especially, we used molecular beam epitaxy to achieve high quality TI thin films with extremely low defect concentrations and an ideal interface between the films and substrates. To optimize the morphology and microstructural quality of the films, a two-step growth was performed on h-BN layers transferred on transmission electron microscopy (TEM) compatible substrates. The resulting $Bi_2Se_3$ thin films were highly crystalline with atomically smooth terraces over a large area, and the $Bi_2Se_3$ and h-BN exhibited a clear heteroepitaxial relationship with an atomically abrupt and clean interface, as examined by high-resolution TEM. Magnetotransport characterizations revealed that this interface supports a high quality topological surface state devoid of bulk contribution, as evidenced by Hall, Shubnikov-de Haas, and weak anti-localization measurements. We believe that the experimental scheme demonstrated in this talk can serve as a promising method for the preparation of high quality TI thin films as well as many other heterostructures based on 2D vdW layered materials.

• Journal of Chest Surgery
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• v.34 no.9
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• pp.653-661
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• 2001

Background: Retrograde cerebral perfusion(RCP) is one of the methods used for brain protection during aortic arch surgery. The author previously published the data, however, for the safety of it, there still remains many controversies. The author performed RCP and checked various parameters to clarify the possibility of early detection of cerebral injury. Material and Method: The author used pigs(Landrace species) weighing 25 to 30kg and performed RCP for 120 minutes. After weaning of cardiopulmonary bypass, we observed pigs for another 120 minutes. Rectal temperature, jugular venous oxygen saturation, central venous pressure were continuously monitored, and the hemodynamic values, histological changes, and serum levels of neuron-specific enolose(NSE) and S100$\beta$ protein were checked. Central venous pressure during RCP was maintained in the range of 20 to 25 mmHg. Result: Flow rates(ml/min) during RCP were 224.3$\pm$87.5(20min), 227.1$\pm$111.0(40min), 221.4$\pm$119.5(60min), 230.0$\pm$136.5(80min), 234.3$\pm$146.1(100min), and 184.3$\pm$50.5(120min). Serum levels of NSE did not increase after retrograde cerebral perfusion. Serum levels of S100$\beta$ protein(ng/ml) were 0.12$\pm$0.07(induction of anesthesia), 0.12$\pm$0.07(soon after CPB), 0.19$\pm$0.12(20min after CPB), 0.25$\pm$0.06(RCP 20min), 0.29$\pm$0.08(RCP 40min), 0.41$\pm$0.05(60min), 0.49$\pm$0.03(RCP 80min), 0.51$\pm$0.10(RCP 100min), 0.46$\pm$0.11(RCP 120min), 0.52$\pm$0.15(CPBoff 60min), 0.62$\pm$0.15(60min after rewarming), 0.76$\pm$0.17(CPBoff 30min), 0.81$\pm$0.20(CPBoff 60min), 0.84$\pm$0.23(CPBoff 90min) and 0.94$\pm$0.33(CPBoff 120min). The levels of S100$\beta$ after RCP were significantly higher than thosebefore RCP(p<0.05). The author could observe the mitochondrial swellings using transmission electron microscopy in neocortex, basal ganglia and hippocampus(CA1 region). Conclusion: The author observed the increase of serum S100$\beta$ after 120 minutes of RCP. The correlation between its level and brain injury is still unclear. The results should be reevaluated with longterm survival model also considering the confounding factors like cardiopulmonary bypass.