• Food Science of Animal Resources
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• v.42 no.5
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• pp.800-815
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• 2022

This study aimed to obtain high Fischer's ratio oligopeptides from goat whey (HFO) and investigate antioxidant property of it. Hydrolysis of goat whey was done with the approach of sequential digestion of pepsin and flavourzyme. With the adsorption of aromatic amino acids by activated carbon, HFO with a Fischer's ratio of 27.070 and a molecular weight of 200-1,000 Da were obtained, and the branched-chain amino acids accounted for 22.87%. Then the antioxidant activity of HFO was evaluated. At the concentrations of 2.0 mg/mL and 0.50 mg/mL, HFO scavenged 77.27% and 99.63% of 1,1-diphenyl-2-picrylhydrazyl and 3-ethylbenzthiazoline-6-sulphonate free radicals respectively. The scavenging rate of HFO against hydroxyl radicals reached 92.31% at the concentration of 0.25 mg/mL. Animal experiments demonstrated that HFO could moderate the changes of malondialdehyde, superoxide dismutase and glutathione peroxidase caused by CCl₄-induced oxidative stress in vivo. This study indicated that HFO from goat whey was capable of oxidation resistance both in vivo and in vitro, which provided a scientific basis for the high-value processing and application of goat milk whey.

• Molecules and Cells
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• v.46 no.8
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• pp.496-512
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• 2023

A fructose-enriched diet is thought to contribute to hepatic injury in developing non-alcoholic steatohepatitis (NASH). However, the cellular mechanism of fructose-induced hepatic damage remains poorly understood. This study aimed to determine whether fructose induces cell death in primary hepatocytes, and if so, to establish the underlying cellular mechanisms. Our results revealed that treatment with high fructose concentrations for 48 h induced mitochondria-mediated apoptotic death in mouse primary hepatocytes (MPHs). Endoplasmic reticulum stress responses were involved in fructose-induced death as the levels of phosho-eIF2α, phospho-C-Jun-N-terminal kinase (JNK), and C/EBP homologous protein (CHOP) increased, and a chemical chaperone tauroursodeoxycholic acid (TUDCA) prevented cell death. The impaired oxidation metabolism of fatty acids was also possibly involved in the fructose-induced toxicity as treatment with an AMP-activated kinase (AMPK) activator and a PPAR-α agonist significantly protected against fructose-induced death, while carnitine palmitoyl transferase I inhibitor exacerbated the toxicity. However, uric acid-mediated toxicity was not involved in fructose-induced death as uric acid was not toxic to MPHs, and the inhibition of xanthine oxidase (a key enzyme in uric acid synthesis) did not affect cell death. On the other hand, treatment with inhibitors of the nicotinamide adenine dinucleotide (NAD)⁺-consuming enzyme CD38 or CD38 gene knockdown significantly protected against fructose-induced toxicity in MPHs, and fructose treatment increased CD38 levels. These data suggest that CD38 upregulation plays a role in hepatic injury in the fructose-enriched diet-mediated NASH. Thus, CD38 inhibition may be a promising therapeutic strategy to prevent fructose-enriched diet-mediated NASH.

• CORROSION AND PROTECTION
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• v.12 no.1
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• pp.30-38
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• 2013

Austenitic stainless steels and Ni-base alloys are widely used as structural materials for major components and piping system in pressurized water reactors (PWRs). These austenitic alloys are known to be susceptible to environmental assisted cracking (EAC), such as environmentally-assisted fatigue (EAF) and primary water stress corrosion cracking (PWSCC) during long-term exposure to PWR primary water environment. In this paper, the current understanding on the phenomena and mechanisms of these EAC are briefly introduced using experimental results and literature review. The mechanisms for EAF and PWSCC for austenitic stainless steels and Ni-base alloys are discussed. Currently, austenitic stainless steels are known to be more susceptible to EAF, while less susceptible to PWSCC than Ni-base alloys. The possible explanations to such behaviors are proposed and discussed in view of the role of hydrogen and internal oxidation.

• Journal of Electrochemical Science and Technology
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• v.14 no.4
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• pp.388-396
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• 2023

Photoelectrochemical (PEC) water splitting is a vital source of clean and sustainable hydrogen energy. Moreover, the large-scale H₂ production is currently necessary, while long-term stability and high PEC activity still remain important issues. In this study, a GaN-based photoelectrode was modified by an additional NH₃ treatment (900℃ for 10 min) and its PEC behavior was monitored. The bare GaN exhibited a highly crystalline wurtzite structure with the (002) plane and the optical bandgap was approximately 3.2 eV. In comparison, the NH₃-treated GaN film exhibited slightly reduced crystallinity and a small improvement in light absorption, resulting from the lattice stress or cracks induced by the excessive N supply. The minor surface nanotexturing created more surface area, providing electroactive reacting sites. From the surface XPS analysis, the formation of an N-Ga-O phase on the surface region of the GaN film was confirmed, which suppressed the charge recombination process and the positive shift of E_FB. Therefore, these effects boosted the PEC activity of the NH₃-treated GaN film, with J values of approximately 0.35 and 0.78 mA·cm^-2 at 0.0 and 1.23 V_RHE, respectively, and an onset potential (V_on) of -0.24 V_RHE. In addition, there was an approximate 50% improvement in the J value within the highly applied potential region with a positive shift of V_on. This result could be explained by the increased nanotexturing on the surface structure, the newly formed defect/trap states correlated to the positive V_on shift, and the formation of a GaO_xN_1-x phase, which partially blocked the charge recombination reaction.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.3
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• pp.146-154
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• 2024

In this paper, we present a convenient liquid crystal (LC) molecular alignment method using brush hairs as an alternative to the rubbing process in the LC display industry. Titanium strontium yttrium zirconium oxide (TiSrYZrO) solution was prepared using a sol-gel process, and the TiSrYZrO alignment film production and LC molecular alignment were integrated through a one-step brush coating process. As the curing temperature increased, the LC molecule alignment of the LC cell improved, and the formation of a physical surface anisotropic structure due to the shear stress caused by the movement of the brush hairs on the coating surface led to uniform alignment of the LC molecules. Uniform and homogeneous LC molecular alignment was confirmed through polarizing optical microscopy and pretilt angle measurement. Through thermal oxidation using X-ray photoelectron spectroscopy, the TiSrYZrO thin film well formed of metal oxide was confirmed and verified to have excellent optical transparency. From these results, it is expected that a convenient LC molecular alignment method using brush hairs as an alternative to the rubbing process will be a viable next-generation technology.

• The Korean Journal of Food And Nutrition
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• v.28 no.1
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• pp.34-39
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• 2015

In this study, portective effect on DNA damage several mushrooms (Pleurotus ostreatus, Flammulina velutipes, Lentinula edodes) according to cooking methods was investigated using Comet assay. Three edible mushrooms were cooked by grilling, blanching, pan-frying, or by preparing 'Jeon' (traditional Korean pancake). Cells were incubated in medium with 4 kinds of samples for 48 h ($37^{\circ}C$) were further treated with hydrogen peroxide ($H_2O_2$) for 5 min as an oxidative stimulus. Oxidative damage was evaluated by single-cell gel electrophoresis (Comet assay) and quantified by tail DNA% (TD), tail length (TL), tail moment (TM). Though oxidative DNA damages expressed as TD, TL, TM of 4 cooked samples were higher than raw sample, which means lower protective activities, all samples including raw sample had significantly higher protective effects than the positive control (p<0.05). The protective effect on DNA damage of cooked samples decreased much more when soybean oil added, likely due to the thermal oxidation of oil during cooking. Although heat treatment could degrade protective effect on DNA damage of mushrooms, the cooked mushroom had significant effect on oxidative stress. In conclusion, grilling and blanching were the most advantageous cooking methods to protect oxidative DNA damage induced by $H_2O_2$.

• Biomedical Science Letters
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• v.12 no.2
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• pp.81-89
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• 2006

The ischemia-responsive 94 gene (irp94) encoding a 94 kDa endoplasmic reticulum resident protein was investigated its molecular properties associated with unfoled protein responses. First, the expression of irp94 mRNA was tested after the reperfusion of the transient forebrain ischemia induction at the central nervous system in three Mongolian gerbils. Second, irp94 expression in PC12 cells, which are derived from transplantable rat pheochromocytoma cultured in the DMEM media, was tested at transcriptional and translational levels. The half life of irp94 mRNA was also determined In PC12 cells. Last, the changes of irp94 mRNA expression were investigated by the addition of various ER stress inducible chemicals (A23187, BFA, tunicamycin, DTT and $H_2O_2$) and proteasome inhibitors, and heat shock. High level expression of irp94 mRNA was detected after 3 hours reperfusion in the both sites of the cerebral cortex and hippocampus of the gerbil brain. The main regulation of irp94 mRNA expression in PC 12 cells was determined at the transcriptional level. The half life of irp94 mRNA in PC12 cells was approximately 5 hours after the initial translation. The remarkable expression of irp94 mRNA was detected by the treatment of tunicamycin, which blocks glycosylation of newly synthesized polypeptides, and $H_2O_2$, which induces apoptosis. When PC12 cells were treated with the cytosol proteasome inhibitors such as ALLN (N-acetyl-leucyl-norleucinal) and MG 132 (methylguanidine), irp94 mRNA expression was increased. These results indicate that expression of irp94 was induced by ER stress including oxidation condition and glycosylation blocking in proteins. Expression of irp94 was increased when the cells were chased after heat shock, suggesting that irp94 may be involved in recovery rather than protection against ER stresses. In addition, irp94 expression was remarkably increased when cytosol proteasomes were inhibited by ALLN and MG 132, suggesting that irp94 plays an important role for maintaining the ERAD (endoplasmic reticulum associated degradation) function.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.5
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• pp.611-616
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• 2013

Alcoholic liver disease (ALD) is a major cause of morbidity and mortality around the world. Although much progress has been made in understanding the pathogenesis of ALD, there remains no effective therapy for it. Accumulated evidence indicates that oxidative stress is the main pathological factors in the development of ALD. Ethanol administration causes accumulation of reactive oxygen species (ROS), including superoxide, hydroxyl radical, and hydrogen peroxide. ROS, in turn, cause lipid peroxidation of cellular membranes, and protein and DNA oxidation, which results in hepatocyte injury. In addition to pro-oxidants formation, antioxidants depletion caused by ethanol administration also results in oxidative stress. The objective of this study is to investigate the effects of Shiryung-tang extract on the chronic alcoholic liver injury induced by EtOH. Male Sprague Dawley rats were used in this study. All rats were maintained under standard laboratory conditions ($23{\pm}1^{\circ}C$, 12h light/12h dark cycles). All animals (n=30) were randomly divided into following groups: (1) Normal group, treated with distilled water (n=10); (2) Control group, treated with ethanol (n=10); (3) Sample group, treated with ethanol + pharmacopuncture (n=10). For oral administration of ethanol in Control and Sample group, the ethanol was dissolved in distilled water in concentrations of 25%(v/v). Throughout the experiment of 8 week, the rats were allowed free access to water and standard chow. Sample group were administrated by Shiryung-tang extract daily for 8 weeks. Control group were given normal saline for same weeks. As a results, the oral administration of ethanol for 8 weeks leads to hepatotoxicity. The levels of hepatic marker such as HDL-cholesterol, triglyceride, aspartate aminotransferase and alanine aminotransferase were altered. The ethanol also increased lipid peroxidation and depletion of antioxidant enzyme activities as well as hepatic tissue injury. However, the treatment of Shiryung-tang extract prevented all the alterations induced by ethanol and returned their levels to near normal. These data suggest that Shiryung-tang extract could have a beneficial effect in inhibiting the oxidative damage induced by chronic ethanol administration. Therefore, Shiryung-tang extract can be a candidate to protect against EtOH-induced liver injury.

• The Plant Pathology Journal
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• v.30 no.4
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• pp.343-354
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• 2014

Rice blast disease caused by Magnaporthe oryzae is one of the most serious diseases of cultivated rice (Oryza sativa L.) in most rice-growing regions of the world. In order to investigate early response genes in rice, we utilized the transcriptome analysis approach using a 300 K tilling microarray to rice leaves infected with compatible and incompatible M. oryzae strains. Prior to the microarray experiment, total RNA was validated by measuring the differential expression of rice defense-related marker genes (chitinase 2, barwin, PBZ1, and PR-10) by RT-PCR, and phytoalexins (sakuranetin and momilactone A) with HPLC. Microarray analysis revealed that 231 genes were up-regulated (>2 fold change, p < 0.05) in the incompatible interaction compared to the compatible one. Highly expressed genes were functionally characterized into metabolic processes and oxidation-reduction categories. The oxidative stress response was induced in both early and later infection stages. Biotic stress overview from MapMan analysis revealed that the phytohormone ethylene as well as signaling molecules jasmonic acid and salicylic acid is important for defense gene regulation. WRKY and Myb transcription factors were also involved in signal transduction processes. Additionally, receptor-like kinases were more likely associated with the defense response, and their expression patterns were validated by RT-PCR. Our results suggest that candidate genes, including receptor-like protein kinases, may play a key role in disease resistance against M. oryzae attack.

• Nutrition Research and Practice
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• v.8 no.5
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• pp.509-515
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• 2014

BACKGROUND/OBJECTIVES: The root of Vitis amurensis Ruprecht, a sort of wild-growing grape, has been used in oriental medicine for treatment of skin ailments; however, its dermatological activity is not sufficiently understood. The aim of this study was to investigate tyrosinase inhibitory and anti-melanogenic activities of V. amurensis Ruprecht root methanol extract (VARM) in B16F10 mouse melanoma cells and to attempt to isolate and identify the active compound issued from VARM. MATERIALS/METHODS: Anti-melanogenic activity of VARM was analyzed in ${\alpha}$-melanocyte stimulating hormone (MSH)-stimulated B16F10 cells through evaluation of antioxidative activity as well as inhibited tyrosinase activity and melanin contents compared with those of kojic acid and arbutin. After anti-melanogenic analysis of VARM, serial fractionation, nuclear magnetic resonance (NMR), and thin layer chromatorgraphy (TLC) were applied for identification of active compounds contained in VARM. RESULTS: VARM significantly inhibited oxidative stress and tyrosinase activity and attenuated ${\alpha}$-MSH-induced melanin production in B16F10 cells. For isolation of active compounds, VARM was fractionated using a series of organic solvents, including dichloromethane ($CH_2Cl_2$), ethyl acetate (EtOAc), and n-butanol (n-BuOH). Among fractions showing anti-melanogenic activity, the CH2Cl2 fraction induced the most potent attenuation of melanogenesis without cytotoxicity and the major compound in the $CH_2Cl_2$ fraction was identified as betulinic acid. Betulinic acid isolated from the $CH_2Cl_2$ fraction of VARM significantly attenuated ${\alpha}$-MSH-induced melanogenesis in a dose dependent manner, which was stronger than that of arbutin used as a positive control. CONCLUSIONS: These results indicate that VARM inhibits oxidative stress, tyrosinase activity, and ${\alpha}$-MSH-induced melanogenesis in B16F10 cells, due primarily to the active compound, betulinic acid, in the $CH_2Cl_2$ fraction.