• Biomolecules & Therapeutics
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• v.18 no.2
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• pp.145-151
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• 2010

Oxygen supply into inside solid tumor is often diminished, which is called hypoxia. Many gene transcriptions were activated by hypoxia-inducible factor (HIF)-$1{\alpha}$. Here, we investigated the effect of hypoxia on paclitaxel-resistance induction in HeLa cervical tumor cells. When HeLa cells were incubated under hypoxia condition, HIF-$1{\alpha}$ level was increased. In contrast, paclitaxel-mediated tumor cell death was reduced by the incubation under hypoxia condition. Paclitaxel-mediated tumor cell death was also inhibited by treatment with DMOG, chemical HIF-$1{\alpha}$ stabilizer, in a dose-dependent manner. A significant increase in intracellular ROS level was detected by the incubation under hypoxia condition. A basal level of cell density was increased in response to 10 nM $H_2O_2$. HIF-$1{\alpha}$ level was increased by treatment with various concentration of $H_2O_2$. The increased level of HIF-$1{\alpha}$ by hypoxia was reduced by the treatment with N-acetylcysteine (NAC), a well-known ROS scavenger. Paclitaxel-mediated tumor cell death was increased by treatment with NAC. Taken together, these findings demonstrate that hypoxia could play a role in paclitaxel-resistance induction through ROS-mediated HIF-$1{\alpha}$ stabilization. These results suggest that hypoxia-induced ROS could, in part, control tumor cell death through an increase in HIF-$1{\alpha}$ level.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.207-207
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• 1996

Through molecular cloning, five muscarinic receptors have been identified. The muscarinic receptors can be generally grouped according to their coupling to either stimulation of phospholipase C (m1, m3, and m5) or the inhibition of adenylate cyclase (m2 and m4). Each m1, m3, and m5 receptors has the additional potential to couple to the activation of phospholipase A$_2$, C, and D, tyrosine kinase, and the mobilization of Ca$\^$2+/. However, the differences in coupling efficiencies to different second messenger systems between these receptors have not been studied well. Ectopic expression of each of these receptors in mammalian cells has provided the opportunity to evaluate the signal transduction of each in some detail. In this work we compared the coupling efficiencies of the m1, m3 and m5 muscarinic receptors expressed in chinese hamster ovary (CHO) cells to the Ca$\^$2+/ mobilization and the stimulation of neuronal nitric oxide synthase (nNOS). Because G protein/PLC/PI turnover/[(Ca$\^$2+/])i/NOS pathway was supposed as a main pathway for the production of nitric oxide via muscarinic receptors, we studied on ml, m3 and m5 receptors. Stimulation of guanylate cyclase activity in detector neuroblastoma cells was used as an index of generation nitric oxide (NO) in CHO cells. The agonist carbachol increased the cGMP formation and the intracellular [Ca$\^$2+/] in concentration dependent manner in three types of receptors and the increased cGMP formation was significantly attenuated by scavenger of NO or inhibitor of NOS. m5 receptors was most efficiently coupled to stimulation of nNOS, And, the coupling efficiencies to the stimulation of neuronal nitric oxide synthase in three types of receptors were parallel with them to the Ca$\^$2+/ mobilization.

• Herbal Formula Science
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• v.8 no.1
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• pp.147-167
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• 2000

Reactive oxygen species (ROS) play an important role in the pathogenesis of a variety of life threatening conditions such as atherosclerosis, myocardial infarction and cerebral stroke. In this study, the effect of Sunghyangchungisan (SHCS) as a cytoproctant against ROS-induced cell injury was studied by investigating its effect on $H_{2}O_2-induced$ cell injury in cultured endothelial cells derived from the human umbilical vein. SHCS effectively proteced the cells against $H_{2}O_2-induced$ injury determined by trypan blue exclusion ability and lactate dehydrogenase (LDH) release. The effect of SHCS was concentration-dependent and the concentrations to inhibit by 50% the cell death and LDH release were $0.9{\pm}0.1$ and $1.2{\pm}0.1\;mg/ml$, respectively. In addition, SHCS effectively protected the cells against t-butylhydroperoside- and menadione-Induced injury as well. SHCS inhibited lipid peroxidation determined by malondialdehyde production. SHCS exerted as an effective scavenger of ROS produced by exposing the cells to $H_{2}O_2$ The activities of the intracellular ROS scavenging enzymes such as superoxide dismutase, catalase and glutathione peroxidase were not Influenced by SHCS.These results indicate that SHCS might exert as an effective cytoprotectant against ROS-induced cell injury. Further intensive studies would provide us insights into mechanisms of the pharmacological actions of SHCS.

• Biomolecules & Therapeutics
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• v.12 no.1
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• pp.25-33
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• 2004

In this study we investigated whether ATP loss was involved in the potentiated death of immunostimulated rat primary astrocytes in glucose-deprived condition. Rat primary astrocytes immunostimulated with LPS plus IFN-${\gamma}$ for 48 h underwent death upon glucose deprivation, which dependent on the production of peroxynitrite. Intracellular ATP level synergistically decreased by glucose deprivation in immunostimulated astrocytes but not in control cells, and the loss of ATP occurred well ahead of the LDH release. The synergistic cell death and ATP loss by immunostimulation and glucose deprivation were inhibited by iNOS inhibitor (L-NAME and L-NNA) or peroxynitrite decomposition catalyst (also a superoxide anion scavenger), Mn(III)tetrakis(N-methyl-4'-pyridyl)porphyrin (MnTMPyP). Exogenous addition of peroxynitrite generator, SIN-l timedependently induced ATP loss and cell death in the glucose-deprived astrocytes. Depletion of intracellular glutathione (GSH) and dis겨ption of mitochondrial transmembrane potential (MTP) were also observed under same conditions. Supply cellular ATP by the addition of exogenous adenosine or ATP during glucose deprivation inhibited ATP depletion, GSH depletion, MTP disruption and cell death in SIN-l treated or immunostimulated astrocytes. This study showed that perturbation in the regulation of intracellular ATP level in immunostimulated astrocytes might make them more vulnerable to energy challenging stimuli.

• BMB Reports
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• v.50 no.10
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• pp.528-533
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• 2017

Peroxiredoxin I (Prx I) plays an important role as a reactive oxygen species (ROS) scavenger in protecting and maintaining cellular homeostasis; however, the underlying mechanisms are not well understood. Here, we identified a critical role of Prx I in protecting cells against ROS-mediated cellular senescence by suppression of $p16^{INK4a}$ expression. Compared to wild-type mouse embryonic fibroblasts (WT-MEFs), Prx $I^{-/-}$ MEFs exhibited senescence-associated phenotypes. Moreover, the aged Prx $I^{-/-}$ mice showed an increased number of cells with senescence associated-${\beta}$-galactosidase (SA-${\beta}$-gal) activity in a variety of tissues. Increased ROS levels and SA-${\beta}$-gal activity, and reduction of chemical antioxidant in Prx $I^{-/-}$ MEF further supported an essential role of Prx I peroxidase activity in cellular senescence that is mediated by oxidative stress. The up-regulation of $p16^{INK4a}$ expression in Prx $I^{-/-}$ and suppression by overexpression of Prx I indicate that Prx I possibly modulate cellular senescence through $ROS/p16^{INK4a}$ pathway.

• International Journal of Oral Biology
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• v.39 no.4
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• pp.229-236
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• 2014

Reactive oxygen species (ROS) and nitrogen species (RNS) are implicated in cellular signaling processes and as a cause of oxidative stress. Recent studies indicate that ROS and RNS are important signaling molecules involved in nociceptive transmission. Xanthine oxidase (XO) system is a well-known system for superoxide anions ($O{_2}^{{\cdot}_-}$) generation, and sodium nitroprusside (SNP) is a representative nitric oxide (NO) donor. Patch clamp recording in spinal slices was used to investigate the role of $O{_2}^{{\cdot}_-}$ and NO on substantia gelatinosa (SG) neuronal excitability. Application of xanthine and xanthine oxidase (X/XO) compound induced membrane depolarization. Low concentration SNP ($10{\mu}M$) induced depolarization of the membrane, whereas high concentration SNP (1 mM) evoked membrane hyperpolarization. These responses were significantly decreased by pretreatment with phenyl N-tert-butylnitrone (PBN; nonspecific ROS and RNS scavenger). Addition of thapsigargin to an external calcium free solution for blocking synaptic transmission, led to significantly decreased X/XO-induced responses. Additionally, X/XO and SNP-induced responses were unchanged in the presence of intracellular applied PBN, indicative of the involvement of presynaptic action. Inclusion of GDP-${\beta}$-S or suramin (G protein inhibitors) in the patch pipette decreased SNP-induced responses, whereas it failed to decrease X/XO-induced responses. Pretreatment with n-ethylmaleimide (NEM; thiol-alkylating agent) decreased the effects of SNP, suggesting that these responses were mediated by direct oxidation of channel protein, whereas X/XO-induced responses were unchanged. These data suggested that ROS and RNS play distinct roles in the regulation of the membrane excitability of SG neurons related to the pain transmission.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.22-26
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• 2014

Protocatechualdehyde (PA) is phenolic compound having antioxidative and antitumor activities. PA was purified from supernatant of Streptomyces lincolnensis M-20. In the presence of copper ion, PA acted as pro-oxidant. The antioxidant activity was assessed with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, and the pro-oxidant effect of PA on DNA damage as pBR322 plasmid DNA-cleaving agents in the presence of Cu(II) ions was investigated. The involvement of reactive oxygen species (ROS) in the DNA damage was confirmed by the inhibition of the DNA breakage by using glutathione (GSH), specific scavenger of ROS. When the increase in ROS reaches a certain level (the toxic threshold), it may trigger cell death. The formation of the PA/Cu(II) chelate complex was confirmed by reaction with ethylenediamine-tetraacetic acid (EDTA), a well-known chelating agent for metal ions, by using UV/Vis spectroscopic analysis.

• Fire Science and Engineering
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• v.19 no.3 s.59
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• pp.13-19
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• 2005

An experimental study is presented for extinguishing characteristics of liquid fuel fire by water mist containing sodium acetate trihydrate. To evaluate the extinguishing performance of water mist containing an additive, the evaporation characteristics of a water droplet on a heated surface was examined. The evaporation process was recorded by a charge-coupled-device camera. Also, small-scale extinguishing tests were conducted for n-heptane pool fire in ventilated space to measure flame temperature variation. The average evaporation rate of a water droplet containing an additive was lower than that of a pure water droplet at a given surface temperature due to the precipitation of salt in the liquid-film and change of surface tension. In case of using an additive, the flame temperature was lower than that of pure water at a given discharge pressure and it was because the momentum of a water droplet containing an additive was increased reducing flame size. And also dissociated metal atoms, sodium, were reacted as a scavenger of the major radical species OH^-,\;H^+$ which were generated for combustion process. Moreover, at a high pressure of 4MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.90-98
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• 2007

The antioxidant activities of water ($H_2O$) and ethanol (EtOH) extracts from hamcho (Salicornia herbacea L.) juice and cake prepared by enzymatic treatments were evaluated by in vitro assays against DPPH, superoxide, and hydroxyl radicals. Among the $H_2O$ and EtOH extracts from five different carbohydrases treated, the EtOH extract from viscozyme-treated hamcho cake had higher yield and phenolic content, and exhibited the strongest radical scavenging activity against DPPH ($IC_{50}=186.91\;{\mu}g/mL$), superoxide ($IC_{50}=87.54\;{\mu}g/mL$), and hydroxyl radicals ($IC_{50}=367.07\;{\mu}g/mL$). Antioxidant assay-guided fractionation and purification of the EtOH extract led to isolation and identification of five phenolic compounds, procatechuic, ferulic and caffeic acids, quercetin, and isorhamnetin. Most of these phenolic compounds exhibited considerable DPPH, superoxide, and hydroxyl radical scavenging activities, and in particular, caffeic and ferulic acids had stronger superoxide and hydroxyl radical scavenging activities than the well-known antioxidant radical scavenger, (+)-catechin (p<0.05). Quercetin and isorhamnetin were the primary compounds responsible for the strong antioxidant activity in the EtOH extract of the viscozyme-treated hamcho cake. Meanwhile, these five phenolic compounds were detected in the EtOH extract of the viscozyme-treated hamcho cake at the following levels (dry base of hamcho); procatechuic acid (1.54 mg%), caffeic acid (6.87 mg%), ferulic acid (8.45 mg%), quercetin (12.63 mg%), and isorhamnetin (6.65 mg%). However, three of these phenolic compounds (procatechuic, caffeic acid, and ferulic acids) were detectable in the $H_2O$ extract of viscozyme-treated hamcho juice. These results suggest that the EtOH extract of viscozyme-treated hamcho cake may be a potential source of natural antioxidants.

• Molecules and Cells
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• v.41 no.5
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• pp.401-412
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• 2018

Oxymatrine (OMT) often used in treatment for chronic hepatitis B virus infection in clinic. However, OMT-induced liver injury has been reported. In this study, we aim to investigate the possible mechanism of OMT-induced hepatotoxicity in human normal liver cells (L02). Exposed cells to OMT, the cell viability was decreased and apoptosis rate increased, the intracellular markers of oxidative stress were changed. Simultaneously, OMT altered apoptotic related proteins levels, including Bcl-2, Bax and pro-caspase-8/-9/-3. In addition, OMT enhanced the protein levels of endoplasmic reticulum (ER) stress makers (GRP78/Bip, CHOP, and cleaved-Caspase-4) and phosphorylation of c-Jun N-terminal kinase (p-JNK), as well as the mRNA levels of GRP78/Bip, CHOP, caspase-4, and ER stress sensors (IREI, ATF6, and PERK). Pre-treatment with Z-VAD-fmk, JNK inhibitor SP600125 and N-acetyl-l-cysteine (NAC), a ROS scavenger, partly improved the survival rates and restored OMT-induced cellular damage, and reduced caspase-3 cleavage. SP600125 or NAC reduced OMT-induced p-JNK and NAC significantly lowered caspase-4. Furthermore, 4-PBA, the ER stress inhibitor, weakened inhibitory effect of OMT on cells, on the contrary, TM worsen. 4-PBA also reduced the levels of p-JNK and cleaved-caspase-3 proteins. Therefore, OMT-induced injury in L02 cells was related to ROS mediated p-JNK and ER stress induction. Antioxidant, by inhibition of p-JNK or ER stress, may be a feasible method to alleviate OMT-induced liver injury.