• Animal cells and systems
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• v.2 no.1
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• pp.49-53
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• 1998

The winter-resident Korean bats, Murina leucogaster ognevi, show a circadian cycle of thermoregulation and locomotion in summer, as do other bat species in temperate regions. They are most active between dusk and dawn with body temperature (Tb) of 35-4OC, and are usually torpid in their roost sites for the rest of day with their Tb close to ambient temperature (Ta) of around 15C. The present study was conducted to determine thermogenic and thermolabile properties of the heterothermic bats that would influence their daily feeding activities and ultimately, their energy conservation strategy. Testing on active male Murina, resting metabolic rate (RMR, gauged by oxygen consumption rate) at the lower limit of thermoneutral zone (31C) was 2.0 L kq-1 h-1. The regression slope of RMR below the thermoneutral zone (an index of metabolic thermal sensitivity) was -0.38 L $kg^{-l} h^{-1} C^{-1}$. The metabolic rate at the roost Ta (15C) was 4.5 times the lowest RMR in the active state but becomes nearly zero in the torpid state. This implies that by being torpid during daytime (between dawn and dusk), the individual bats would save about 4.7 kcal each day in mid-summer. Interspecific comparisons of thermal metabolic response over a mass scale suggest that the smaller bats show a relatively higher metabolic rate in thermoneutral zone and a greater thermal sensitivity of metabolism, which follows the general principle seen in homeothermic metabolism. Thermolabile features in metabolic responses seem to be fairly common for these bats in conditions other than a fully active state. Types of thermolabile responses and their energetic significance are discussed.

• Korean Journal of Medicinal Crop Science
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• v.25 no.5
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• pp.315-321
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• 2017

Background: Glycyrrhiza uralensis Radix (GR) is a crude drugs used in Asian countries that has been reported to prevent the progression of neurodegenerative diseases such as Alzheimer's disease. The present study examined whether GR and its active compounds, glycyrrhizic acid (GA) and isoliquiritigenin (IL), exerted protective effects on $H_2O_2$-induced oxidative damage in C6 glial cells. Methods and Results: We exposed C6 glial cells to hydrogen peroxide ($H_2O_2$) for 24 h and investigated the cellular response to GR and its active compounds by evaluating cell viability, reactivie oxygen species (ROS) production, and apoptosis-related protein expression. GR successfully mitigated the reduced cell viability and ROS production induced by $H_2O_2$ in C6 glial cells, IL and GA significantly increased the cell viability and decreased ROS production. In addition, IL and GA down-regulated apoptotic Baxdependent caspase-3 activation, but each compound exerted different mechanisms, i.e., IL dose-dependently decreased ROS production and, GA up-regulated anti-apoptotic Bcl-2 expression. Conclusions: These results demonstrated that GR and its active components, IL and GA, exhibit potential for use as natural neurodegenerative agents for the modulation of apoptosis in C6 glial cells.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.7
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• pp.1053-1062
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• 2011

Reactive oxygen species (ROS), including singlet oxygen (${O_2}^1$), superoxide anion radical ($O_2{\cdot}^-$), hydroxyl radical ($HO{\cdot}$), peroxyl radical ($ROO{\cdot}$), hydrogen peroxide ($H_2O_2$), and hypochlorous (HOCl), are generated as byproducts of normal cellular metabolism. ROS induce damage to many biological molecules, such as lipids, proteins, carbohydrates, and DNA. It is widely believed that some degenerative diseases caused by ROS can be prevented by the high intake of fruits and vegetables due to their antioxidant activities. Recently, research on natural antioxidants has become increasingly active in various fields. Several assays have been developed to measure the total antioxidant capacity of antioxidants in fruits and vegetables in vitro. These assays include those for DPPH radical scavenging activity, SOD-like activity, total polyphenol content, oxygen radical absorbance capacity, reducing power, trolox equivalent antioxidant capacity (ABTS assay), single-cell gel electrophoresis (comet assay), and a cellular antioxidant activity assay. Because different antioxidant compounds may act through different mechanisms in vitro, no single assay can fully evaluate the total antioxidant capacity of foods. Due to the complexity of the composition of foods, it is important to be able to measure antioxidant activity using biologically relevant assays. In this review, recently used assays were selected for extended discussion, including a comparison of the advantages and disadvantages of each assay and their application to fruits and vegetables.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.2
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• pp.113-118
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• 2008

Diel rhythm of oxygen consumption (OC) of the starry flounder Platichthys stellatus was measured at different water temperatures in a closed recirculating seawater system with a respiratory chamber. The fish consumed 70.5, 79.7, and 90.6 mg $O_2/kg/hr$ at 15, 20, and $25^{\circ}C$, respectively, showing a linear increase in OC with water temperature. The OC of fish showed a clear diel rhythm, with lower values during the day and higher values at night, in accordance with the light (09:00-21:00) and dark (21:00-09:00) phases of the diel cycle (12L:12D) in water at 15 and $20^{\circ}C$. However, the OC of the fish showed an unclear diel rhythm with the light and dark phases of the diel cycle at $25^{\circ}C$. The respective OC at 15, 20 and $25^{\circ}C$ was 63.8, 72.4, and 88.4 mg $O_2/kg/hr$ during the light phases and 77.2, 87.1, and 92.8 mg $O_2/kg/hr$ during the dark phase. The starry flounder is thought to be a nocturnal fish with a higher OC at night, while it rests during the day. Its OC was the most stable in the light, when it did not feed. Consequently, the night-time OC is the active OC and the day-time OC is the resting OC in the starry flounder.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.556-563
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• 2007

We carried out a laboratory scale experiment about the characteristics of chemically active species produced in hybrid gas-liquid discharges. The electrode configuration which had high voltage electrode in the gas phase and ground electrode in the liquid was utilized while high voltage electrode has been typically positioned in the liquid in other studies. Our electrode was configured in such a way as to increase the energy efficiency of chemical reactions by creating a higher electrical field strength and a narrower pulse width than the typical electrode configuration. The highest ozone concentration was obtained at 45 kV which was the medium value in operating voltages. The decrease of solution conductivity increased the resistance of liquid phase and the electric field strength through the gas phase, so ozone gene-ration rate was enhanced. The increase of voltage promoted the production rate of hydrogen peroxide by increasing the electric field strength. In a lower voltage, the increase of solution conductivity increased the degradation rate of $H_2O_2$, so the $H_2O_2$ generation rate decreased. On the other hand, the effects of UV radiation, shock waves etc. increased the $H_2O_2$ generation rate as the solution conductivity increased. A higher rate of $H_2O_2$ generation can be achieved by mixing argon to oxygen which generates a stronger and more stable discharges.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.1
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• pp.49-57
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• 2018

In this study, we investigated the anti-aging effect of Rosa damascena extract containing low molecular glycoprotein (RELG) converted from the high molecular glycoprotein by bioconversion. Free radical scavenging activities were performed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Antioxidant activities ($IC_{50}$) of RELG and the positive control ascorbic acid were $22.6{\mu}g/mL$ and $21.1{\mu}g/mL$, respectively. For skin cells, $15{\mu}g/mL$ RELG showed 28% antioxidant activity by inhibiting the production of active oxygen species induced by ultraviolet ray and hydrogen peroxide. $15{\mu}g/mL$ RELG prevented 10% the cell death caused by stress in human hair follicle dermal papilla cells (HDPC) and reduced 90% the production of active oxygen species. In addition, the glycoprotein showed not only anti-wrinkle effect but also moisturizing effect by 48% inhibition of matrix metallo proteinase-1 (MMP-1) production by ultraviolet stress and $10{\mu}g/mL$ RELG enhanced 10% neutral lipid synthesis with 44% aquaporin 3 (AQP3) expression, which is moisture factor. In conclusion, the RELG can be used as an anti-aging cosmetic material.

• Journal of Applied Biological Chemistry
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• v.64 no.2
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• pp.105-112
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• 2021

Excessive accumulation of the amyloid beta (Aβ) peptide has been implicated in the pathogenesis of Alzheimer's disease (AD). Paeonia lactiflora (PL) has been used in treatments of several conditions such as inflammation, arthritis, and cognitive impairment. The purpose of this study was to investigate the neuroprotective effect and mechanisms of PL and its active compound, paeoniflorin (PF), on Aβ_25-35-induced neurotoxicity in SH-SY5Y cells. We evaluated cell viability, lactate dehydrogenase (LDH) release and reactive oxygen species (ROS) production. Furthermore, underlying mechanism of PL and PF on the regulation of amyloidogenic pathway was analyzed by Western blotting. In our results, Aβ_25-35-induced neuronal cell loss was observed, whereas treatment with PL (10, 50, and 100 ㎍/mL) and PF (1, 5, and 10 ㎍/mL) significantly elevated the cell viability, and decreased LDH release and ROS production. In addition, exposure of SH-SY5Y cells to Aβ_25-35 significantly increased the protein levels of amyloid precursor protein (APP)-C-terminal fragment β, β-site APP-cleaving enzyme, and presenilin-1 and -2. However, treatment with PL and PF inhibited the amyloidogenic pathway via the down-regulation of those protein expressions. Taken together, our results indicate that PL, and its active compound PF, could protect SH-SY5Y cells against Aβ_25-35-induced cell neurotoxicity by attenuating LDH release and ROS production, and these effects may be attributed to regulation of amyloidogenic pathway-related protein expression. In conclusion, PL and PF could be a potential to prevent neurodegenerative disorders such as AD.

• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.274-288
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• 2018

This study investigated the environmental factors and fish assemblage in 42 wetlands between spring and autumn of 2017 to evaluate the fish distribution and deduce the management strategy for improving biodiversity in created wetlands located at the Nakdong River basin. The investigation identified a total of 30 fish species and found that the most of wetlands were dominated by exotic fishes such as Micropterus salmoides and Lepomis macrochirus. Fish species such as Rhinogobius brunneus, Opsariichthys uncirostris amurensis, Zacco platypus were less abundant in the area with high density of Micropterus salmoides (static area) because they preferred the environment with active water flow. The pattern analysis of fish distribution in each wetland using the self-organizing map (SOM) showed a total of 24 variables (14 fish species and 10 environmental variables). The comparison of variables indicated that the distribution of fish species varied according to water depth and plant cover rate and was less affected by water temperature, pH, and dissolved oxygen. The plant cover rate was strongly associated with high fish density and species diversity. However, wetlands with low plant biomass had diversity and density of fish species. The results showed that the microhabitat structure, created by macrophytes, was an important factor in determining the diversity and abundance of fish communities because the different species compositions of macrophytes supported diverse fish species in these habitats. Based on the results of this study, we conclude that macrophytes are the key components of lentic freshwater ecosystem heterogeneity, and the inclusion of diverse plant species in wetland construction or restoration schemes will result in ecologically healthy food webs.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.394-402
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• 2014

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and oxygen flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the 2nd voltage (4 kV to 15 kV) was increase, RNO degradation was increased and, generated $H_2O_2$ and $O_3$ concentration were increased. The conductivity of the solution was not influencing the RNO degradation, $H_2O_2$ and $O_3$ generation. The pH effect on RNO degradation was not high. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.3
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• pp.193-201
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• 2023

Hydrogen peroxide (H₂O₂) is a type of active oxygen species (ROS) that causes oxidative stress in cells and affects cell growth, proliferation, senescence, and death. The purpose of this study is to find active peptides that attenuate cytotoxicity of H₂O₂. A positional scanning synthetic tetrapeptide combinatorial library was screened to predict the sequence of potentially active peptides. As a result of comparing the effect of peptide pools on H₂O₂-induced death of human keratinocytes (HaCaT cells), various active peptide sequences were predicted. Especially, peptides containing cysteine (C) residue were predicted to be active. In follow-up experiments, the cytotoxicity and activity of cysteine-containing peptides of different lengths, such as C-NH₂, CC-NH₂, CCC-NH₂, and CCCC-NH₂ were examined. C-NH₂ and CC-NH₂ showed no significant cytotoxicity up to 1.0 mM, but CCC-NH₂, and CCCC-NH₂ showed relatively strong cytotoxicity. C-NH₂ and CC-NH₂ alleviated H₂O₂-induced cytotoxicity. CC-NH₂ was more cytoprotective compared to C-NH₂, C, N-acetyl cysteine (NAC), and glutathione (GSH). When intracellular ROS was measured by flow cytometry, H₂O₂ increased ROS production, and CC-NH₂ suppressed ROS production more effectively than C-NH₂, and it was as effective as C, NAC, and GSH. This study suggests that CC-NH₂ of the cysteine-containing peptides of different lengths has an antioxidant property that safely and effectively alleviates H₂O₂-induced cytotoxicity and ROS production.