• Molecules and Cells
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• v.43 no.5
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• pp.431-437
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• 2020

The hypothalamus is a crucial organ for the maintenance of appropriate body fat storage. Neurons in the hypothalamic arcuate nucleus (ARH) detect energy shortage or surplus via the circulating concentrations of metabolic hormones and nutrients, and then coordinate energy intake and expenditure to maintain energy homeostasis. Malfunction or loss of hypothalamic ARH neurons results in obesity. Accumulated evidence suggests that hypothalamic inflammation is a key pathological mechanism that links chronic overconsumption of a high-fat diet (HFD) with the development of obesity and related metabolic complications. Interestingly, overnutrition-induced hypothalamic inflammation occurs specifically in the ARH, where microglia initiate an inflammatory response by releasing proinflammatory cytokines and chemokines in response to excessive fatty acid flux. Upon more prolonged HFD consumption, astrocytes and perivascular macrophages become involved and sustain hypothalamic inflammation. ARH neurons are victims of hypothalamic inflammation, but they may actively participate in hypothalamic inflammation by sending quiescence or stress signals to surrounding glia. In this mini-review, we describe the current state of knowledge regarding the contributions of neurons and glia, and their interactions, to HFD-induced hypothalamic inflammation.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.3
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• pp.79-84
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• 2007

Because synaptic refinement of medial nucleus of trapezoid body (MNTB) - lateral superior olive (LSO) synapses is most active during the first postnatal week and the long term depression (LTD) has been suggested as one of its mechanisms, LTD of MNTB-LSO synapses was investigated in neonatal rat brain stem slices with the whole cell voltage clamp technique. In $Mg^{2+}$ free condition, tetanus (10 stimuli at 10 Hz for 2 min) in the current clamp mode induced a robust LTD of isolated D, L-APV-sensitive postsynaptic currents (PSCs) for more than 30 min ($n=6,\;2.4{\pm}0.4%$ of the control), while isolated CNQX-sensitive PSCs were not suppressed ($n=6,\;95.3{\pm}1.6%$). Tetanus also elicited similar LTD in the isolated GABAergic/glycinergic PSCs ($n=6,\;3.6{\pm}0.5%$) and mixed PSCs (GABAergic/glycinergic/glutamatergic) ($n=4,\;2.2{\pm}0.7%$). However, such a strong LTD was not observed in the mixed PSCs when 10 mM EGTA was added in the internal solution (n=10), indicating that postsynaptic $Ca^{2+}$ rise is needed for the strong LTD. This robust LTD might contribute to the active synaptic refinement occurring during the first postnatal week.

• Biomolecules & Therapeutics
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• v.28 no.3
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• pp.250-258
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• 2020

Emphysema, a major component of chronic obstructive pulmonary disease (COPD), is a leading cause of human death worldwide. The progressive deterioration of lung function that occurs in the disease is caused by chronic inflammation of the airway and destruction of the lung parenchyma. Despite the main impact of inflammation on the pathogenesis of emphysema, current therapeutic regimens mainly offer symptomatic relief and preservation of lung function with little therapeutic impact. In the present study, we aimed to discover novel therapeutics that suppress the pathogenesis of emphysema. Here, we show that LJ-2698, a novel and highly selective antagonist of the adenosine A₃ receptor, a G protein-coupled receptor involved in various inflammatory diseases, significantly reversed the elastase-induced destructive changes in murine lungs. We found that LJ-2698 significantly prevented elastase-induced airspace enlargement, resulting in restoration of pulmonary function without causing any obvious changes in body weight in mice. LJ-2698 was found to inhibit matrix metalloproteinase activity and pulmonary cell apoptosis in the murine lung. LJ-2698 treatment induced increases in anti-inflammatory cytokines in macrophages at doses that displayed no significant cytotoxicity in normal cell lines derived from various organs. Treatment with LJ-2698 significantly increased the number of anti-inflammatory M2 macrophages in the lungs. These results implicate the adenosine A₃ receptor in the pathogenesis of emphysema. Our findings also demonstrate the potential of LJ-2698 as a novel therapeutic/preventive agent in suppressing disease development with limited toxicity.

• Journal of Ginseng Research
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• v.45 no.1
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• pp.108-118
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• 2021

Background: Korean ginseng (Panax ginseng Meyer) contains a variety of ginsenosides that can be metabolized to a biologically active substance, compound K. Previous research showed that compound K could be enriched in the red ginseng extract (RGE) after hydrolysis by pectinase. The current study investigated whether the enzymatically hydrolyzed red ginseng extract (HRGE) containing a notable level of compound K has cognitive improving and neuroprotective effects. Methods: A scopolamine-induced hypomnesic mouse model was subjected to behavioral tasks, such as the Y-maze, passive avoidance, and the Morris water maze tests. After sacrificing the mice, the brains were collected, histologically examined (hematoxylin and eosin staining), and the expressions of antioxidant proteins analyzed by western blot. Results: Behavioral assessment indicated that the oral administration of HRGE at a dosage of 300 mg/kg body weight reversed scopolamine-induced learning and memory deficits. Histological examination demonstrated that the hippocampal damage observed in scopolamine-treated mouse brains was reduced by HRGE administration. In addition, HRGE administration increased the expression of nuclear-factor-E2-related factor 2 and its downstream antioxidant enzymes NAD(P)H:quinone oxidoreductase and heme oxygenase-1 in hippocampal tissue homogenates. An in vitro assay using HT22 mouse hippocampal neuronal cells demonstrated that HRGE treatment attenuated glutamate-induced cytotoxicity by decreasing the intracellular levels of reactive oxygen species. Conclusion: These findings suggest that HRGE administration can effectively alleviate hippocampus-mediated cognitive impairment, possibly through cytoprotective mechanisms, preventing oxidative-stress-induced neuronal cell death via the upregulation of phase 2 antioxidant molecules.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.2
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• pp.346-351
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• 2003

The current studies investigated the therapeutic effects of Ephedra sinica Stapf (ES) herb-acupuncture on the inflammatory responses of rat arthritic joint, which was induced by the intradermal injection of heat-killed Mycobacterium tuberculosis emulsified in squalene to the base of the tail. The measurements of body weight and articular index were exploited as the assessment methods addressing arthritic symptoms, and the expression profiles of cytokines such as TNF-α, IL-1β and IL-6 in the rat joint were analyzed using RT-PCR. The articular indexes of arthritic rats were significantly restored after the treatment with ES herb-acupuncture. Although the clinical symptoms of arthritic rats were apparently alleviated by the ES treatments, their body weights were not recovered. It maybe due to the weight-loss and energy enhancement effects of ES extracts. The expression of TNF-α, IL-1β and IL-6 genes, which were highly stimulated in the knee joints of arthritic rats, were restored to the levels of normal rats after the ES treatment. The therapeutic effect of ES herb-acupuncture was not observed in ES-treated, non-acupoint arthritic group as a sham control. The ES herb-acupuncture into an acupoint ST36 was found to be effective in alleviating the arthritic symptoms in adjuvant-induced arthritis rats as regards the body weight, joint appearance and the expression profiles of inflammatory cytokines.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.269-275
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• 2004

Different biological tissues have different values of electrical resistivity. In EIT (electrical impedance tomography), we try to provide cross-sectional images of a resistivity distribution inside an electrically conducting subject such as the human body mainly for functional imaging. However, it is well known that the image reconstruction problem in EIT is ill-posed and the quality of a reconstructed image highly depends on the measurement error. This requires us to develop a high-performance EIT system. In this paper, we describe the development of a 16-channel digital EIT system including a single constant current source, 16 voltmeters, main controller, and PC. The system was designed and implemented using the FPGA-based digital technology. The current source injects 50KHz sinusoidal current with the THD (total harmonic distortion) of 0.0029% and amplitude stability of 0.022%. The single current source and switching circuit reduce the measurement error associated with imperfect matching of multiple current sources at the expense of a reduced data acquisition time. The digital voltmeter measuring the induced boundary voltage consists of a differential amplifier, ADC, and FPGA (field programmable gate array). The digital phase-sensitive demodulation technique was implemented in the voltmeter to maximize the SNR (signal-to-noise ratio). Experimental results of 16-channel digital voltmeters showed the SNR of 90dB. We used the developed EIT system to reconstruct resistivity images of a saline phantom containing banana objects. Based on the results, we suggest future improvements for a 64-channel muff-frequency EIT system for three-dimensional dynamic imaging of bio-impedance distributions inside the human body.

• Journal of Ecology and Environment
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• v.31 no.1
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• pp.45-67
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• 2008

Ocean climate variables ($1900{\sim}2005$), time series of catches ($1910{\sim}2005$) and body size data were used to assess the year-to-year and decadal scale fluctuations in abundance of the fish populations (Japanese sardine, anchovy, jack mackerel, chub mackerel, Pacific saury and common squid) that have spawning grounds in the East China Sea and its adjacent regions. A negative correlation between the abundance of pelagic fishes (e.g. jack mackerel) in the Tsushima Warm Current (TWC) region and the Kuroshio-Oyashio Current (KOC) region was attributed to the climatic modulation of larval transport and recruitment, which depends on the winter monsoon-induced drift, current systems, and spawning season and site. The changes in abundance and alternation of dominant fish populations in the two regions in the 1930s, 1970s, and late 1980s mirrored changes in the climate indices (ALPI, AOI and MOI). Oscillations in the decadal climate shifts between the two regions led to zonal differences in larval transport and recruitment, and hence differences in the abundance of the pelagic fish populations. During deep Aleutian Lows, as in the 1980s, larval transport from the East China Sea to the KOC region increases in association with the strong winter Asian monsoon, cool regime and increased volume transport of the Kuroshio Current systems, whereas during a weak Aleutian Low (as in the 1990s), larval transport to the TWC region increased in association with a weak winter Asian monsoon, a warm regime, and increased volume transport of the Tsushima current system. We postulate that the increased chub mackerel abundance in the TWC region and the decreased abundance in the KOC region in the 1990s are partly attributed to changes in recruitment and availability to the fishing fleets under the warm regime in the spawning and nursery grounds in the East China Sea in association with the quasi-steady state of mild winter monsoon in the 1990s. The fluctuations in chub mackerel and jack mackerel abundance are under the environment-dependant growth form, although the tropicalization was identified in the TWC region. The density-dependant growth form was found in Japanese sardine populations, but no tropicalization by fishing was identified in the long ($10{\sim}15$ year) periods of abundance despite their short ($3{\sim}4$ year) generation time, suggesting that the environment-dependant growth form drove the changes in abundance. Year-to-year and decadal scale variations in abundance and population structure of the Pacific saury responded to climate regime shifts (1976/1977, 1988/1989), suggesting that the fish is a key bio-indicators for changes in the ecosystem.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.385-392
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• 2018

This paper presents 2D numerical modeling to calculate ship-ice interactions that occur when an icebreaker advances into ice-covered water. The numerical model calculates repeated icebreaking of an ice plate and removal of small ice floes. The icebreaking of the ice plate is calculated using a ship-ice contact detection technique and fluid-structural interaction of ice plate bending behavior. The ship-ice interactions in small ice floes are calculated using a physically based modeling with 3DOF rigid body equations. The ice plate is broken in crushing, bending, and splitting mode. The ice floes drift by wind or current and by the force induced by the ship-ice interaction. The time history of ice force and ice floe distribution when an icebreaker advances into the ice-covered water are obtained numerically. Numerical results demonstrate that the time history of ice force and distribution of ice floes (ice channel width) depend on the ice floe size, ship motion and ice drifting by wind or current. It is shown that the numerical model of ship maneuvering in realistic ice conditions is necessary to obtain precise information about the ship in ice-covered water. The proposed numerical model can be useful to provide data of a ship operating in ice-covered water.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.142-144
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• 1996

For the accurate analysis of motional characteristics of electrical machines, it is needed to solve the motion equations together with the electromagnetic field equations. In this paper the sequential coupling of systems, the spring mass system and the electromagnetic system, is adopted. The induced current and the magnetic fields are calculated by FEM with given speed. And then, with the computed electromagnetic force, the mechanical equations are solved by the Runge-Kutta method. The above to processes are repeated sequentially to obtain the time domain solutions. The resultant values are applied to the energy conservation law to prove the usefulness of the proposed sequential method.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1563_1564
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• 2009

전자파가 인체에 미치는 영향에 대한 연구중 SAR(Specific Absorption Ratio)에 관한연구는 매우 활발하게 이루어지고 있으나 단파(High Frequency)대역에 의한 인체유도전류에 대한 연구는 미흡한 편이다. 본 연구에서는 근거리장에서 단파대역 RFID 리더 안테나에 의한 인체에 유도되는 전류를 측정하고 이를 등가화 할 수 있는 수직교차루프 형태의 인체등가 모형을 제시하여 인체의 유도전류량과 비교하였다.