• Restorative Dentistry and Endodontics
• /
• 제34권5호
• /
• pp.406-414
• /
• 2009

본 연구의 목적은 심부 상아질과 치수실 상아질에 $H_2O_2$를 각기 다른 적용시간과 농도로 적용하였을 때, 레진수복물과의 미세인장결합강도에 미치는 영향을 평가하는 것이다. 준비된 각각의 치아에 전형적인 근관와동을 형성하고 다음과 같이 무작위로 1개의 대조군과, 4개의 실험군으로 나누었다: 1군, 전처리를 시행하지 않았다; 2군, 20% $H_2O_2$를 20분, 10분, 5분간 적용하였다; 3군, 10% $H_2O_2$를 20분, 10분, 5분간 적용하였다; 4군 5% $H_2O_2$를 20분, 10분, 5분간 적용하였다; 5군, 2.5% $H_2O_2$를 20분, 10분, 5분간 적용하였다. 위와 같이 처리한 후 와동 내를 Superbond C&B(Sunmedical, Co., Shiga, Japan)로 충전하였다. 각 치아는 $37^{\circ}C$ 증류수에 24시간 저장한 뒤 심부 상아질과 치수실 상아질로 잘라 미세인장결합강도 시험을 시행하였다. 각 군에서 측정된 미세인장결합강도를 3-way ANOVA와 Tukey post hoc test로 통계 처리하였다(p < 0.05). 실험 결과 모든 군에서 심부 상아질(D1)의 미세인장 결합강도가 치수실 상아질(D2)보다 높게 나타났다. 평균 결합강도는 $H_2O_2$의 농도와 적용 시간이 증가할수록 감소하였다. 통계분석에서 상아질의 깊이, $H_2O_2$ 농도와 적용 시간이라는 세 가지 변수간의 교호작용 효과는 없으나(p > 0.05). 상아질의 깊이와 $H_2O_2$ 농도 사이, $H_2O_2$ 농도와 적용 시간 사이에서는 교호작용 효과가 있었다(p < 0.05). SEM 관찰에서는 $H_2O_2$의 농도가 증가할수록 상아세관이 좀 더 개방된 양상을 보였다.

• 대한본초학회지
• /
• 제24권2호
• /
• pp.93-98
• /
• 2009

Objectives : Previously we reported that the roots of Panax ginseng C.A. Meyer (Araliaceae) increased sperm count and motility. also induced spermatogenesis via cAMP-responsive element modulator(CREM) activation in rat testes. In this study, for the first step of spermatogenesis in germ cell lines, the antioxidant activity of Panax ginseng were examined in mouse GC-1 spermatogonia cells. Methods : The extract was studied on diphenyl-picryl-hydrazyl (DPPH) radical scavenging activity, GC-1 cell viability by a modified MIT assay. H202-induced cytotoxicity by MIT assay and lipid peroxidation by malondialdehyde (MDA) formation. respectively. Results: The results showed that the extract scavenged DPPH radical with the IC50 being 0.631 mg/mi. The extract at concentrations of 5, and 10, 50, 100, 250 ${\mu}$g/mi increased GC-1 cell viability significantly(p < 0.05, and p < O.O1). Hydrogen peroxide-induced cytotoxicity (73.8%, p < O.O1) was blocked by the extract at concentrations of 50, and 100, 250, 500 ${\mu}$g/ml significantly (p < 0.05, and p < O.O1). The extract at concentrations of 10. and 50 ${\mu}$g/ml decreased the MDA formation on hydrogen peroxide-induced lipid peroxidation. Conclusions : In conclusion, the extract of Panax ginseng has potent antioxidant activity and increases the survival rate of GC-1 spg cells against $H_20_2$-induced cytotoxicity.

• Journal of Ginseng Research
• /
• 제23권3호
• /
• pp.176-181
• /
• 1999

홍삼에서 분리한 수용성 갈변물질의 항산화 활성을 DPPH 수소공여능 및 hydrogen peroxide 시스템에서 조사한 결과를 다음과 같다. 1. DPPH 수소공여능 수용성 갈변물질 S-1, S-2는 반응시간이 경과함에 따라 완만하게 감소하였고, L은 S-1, S-2보다 시간이 경과 함에 따라 감소폭이 증가하였다. L의 경우 BHT, BHA $5{\times}10^{-4}M,\;{\alpha}-tocopherol\;1{\times}10^{-4}M$ 및 ascorbic acid $5.7{\times}10^{-3}M$ 보다 감소폭이 증가하였으나, S-1, S-2는 합성 항산화제와 감소폭이 비슷하였다. 2. Synergist 효과 L, S-1 및 S-2 와 상기의 합성 항산화제 농도와 시너지스트 효과를 조사한 결과, 모든 시험구에서 반응 시간이 경과 함에 따라 감소폭이 증가하여 시너지스트 효과가 나타났다. 3. Hydrogen Peroxide 소거능 :수용성 갈변물질의 hydrgen peroxide 소거능을 조사한 결과, L은 $50\~80\%$, S-1은 $70\~100\%,$ S-1은 모든 첨가구에서 반응 초기부터 $100\%$로 완전히 소거되었다.

• Food Science and Biotechnology
• /
• 제17권2호
• /
• pp.343-348
• /
• 2008

In this study, antioxidant activity of methanol extract of Glycyrrhiza uralensis Fisch (GUE) against $H_2O_2$-induced DNA damage in human leucocytcs and cell death in PC12 cells was determined. The effect of GUE on $H_2O_2$-induced DNA damage in human leucocytcs was evaluated by the comet assay, where GUE ($1-50\;{\mu}g/mL$) was a dose dependent inhibitor of DNA damage induced by $H_2O_2$. The protective effect of GUE against $H_2O_2$-induced damage on PC12 cells was investigated by MTT reduction assay and lactate dehydrogenase release assay. A marked reduction in cell survival induced by $H_2O_2$ was significantly prevented by $1-50\;{\mu}g/mL$ of GUE. The enzyme activity of caspase-3 was elevated in $H_2O_2$-treated PC12 cells, while preincubation with GUE for 30 min inhibited $H_2O_2$-induced caspase-3 activation in a dose-dependent manner. In conclusion, GUE ameliorates $H_2O_2$-induced DNA damage in human leucocytes and has neuroprotective effect by preventing cell death in PC12 cell, suggesting that GU may be a potential candidate for novel therapeutic agents for neuronal diseases associated with oxidative stress.

• The Korean Journal of Physiology and Pharmacology
• /
• 제10권1호
• /
• pp.51-58
• /
• 2006

The promoting effect of hydrogen peroxide ($H_2O_2$) against the cytotoxicity of 1-methyl-4-phenylpyridinium ($MPP^+$) in differentiated PC12 cells was assessed by measuring the effect on the mitochondrial membrane permeability. Treatment of PC12 cells with $MPP^+$ resulted in the nuclear damage, decrease in the mitochondrial transmembrane potential, cytosolic accumulation of cytochrome c, activation of caspase-3, increase in the formation of reactive oxygen species (ROS) and depletion of GSH. Addition of $H_2O_2$ enhanced the $MPP^+-induced$ nuclear damage and cell death. Catalase, Carboxy-PTIO, Mn-TBAP, N-acetylcysteine, cyclosporin A and trifluoperazine inhibited the cytotoxic effect of $MPP^+$ in the presence of $H_2O_2$. Addition of $H_2O_2$ promoted the change in the mitochondrial membrane permeability, ROS formation and decrease in GSH contents due to $MPP^+$ in PC12 cells. The results show that the $H_2O_2$ treatment promotes the cytotoxicity of $MPP^+$ against PC12 cells. $H_2O_2$ may enhance the $MPP^+$-induced viability loss in PC12 cells by promoting the mitochondrial membrane permeability change, release of cytochrome c and subsequent activation of caspase-3, which is associated with the increased formation of ROS and depletion of GSH. The findings suggest that $H_2O_2$ as a promoting agent for the formation of mitochondrial permeability transition may enhance the neuronal cell injury caused by neurotoxins.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
• /
• pp.524-527
• /
• 2000

An electroenzymatic system to oxidize veratryl alcohol of on electrodes with in-situ generated hydrogen peroxide was studied. We investigated hydrogen peroxide generation, current efficiency, and veratryl alcohol oxidation in the electrode system at various conditions. The reaction rates of veratryl alcohol oxidation were compared in an electrochemical, an electroenzymatic, and an usual biochemical systems to prove the concept of electroenzymatic oxidation.

• BMB Reports
• /
• 제36권5호
• /
• pp.488-492
• /
• 2003

Neurofilament-L (NF-L) is a major element of neuronal cytoskeletons and known to be important for neuronal survival in vivo. Since oxidative stress might play a critical role in the pathogenesis of neurodegenerative diseases, we investigated the role of copper and peroxide in the modification of NF-L. When disassembled NF-L was incubated with copper ion and hydrogen peroxide, then the aggregation of protein was proportional to copper and hydrogen peroxide concentrations. Dityrosine crosslink formation was obtained in copper-mediated NF-L aggregates. The copper-mediated modification of NF-L was significantly inhibited by thiol antioxidants, N-acetylcysteine, glutathione, and thiourea. A thioflavin-T binding assay was performed to determine whether the copper/$H_2O_2$ system-induced in vitro aggregation of NF-L displays amyloid-like characteristics. The aggregate of NF-L displayed thioflavin T reactivity, which was reminiscent of amyloid. This study suggests that copper-mediated NF-L modification might be closely related to oxidative reactions which may play a critical role in neurodegenerative diseases.

• BMB Reports
• /
• 제36권3호
• /
• pp.251-257
• /
• 2003

Agmatine, an amine and organic cation, reduced $H_2O_2$ that was generated by hyperglycemia, and transcription factors such as NF-${\kappa}B$ and AP-1 activity in the mesangial cells that were exposed to high glucose. However, spermine which shares a strong nucleophilic structure with agmatine decreased the $H_2O_2$ levels and AP-1, but not the NF-${\kappa}B$ activity. Possible roles for agmatine and spermine in decreasing fibronectin are discussed, and the signaling pathway for agmatine-reduced fibronectin accumulation is presented.

• Journal of Microbiology
• /
• 제38권1호
• /
• pp.18-23
• /
• 2000

Streptomyces coelicolor produces three kinds of catalases to cope with oxidative stress and to allow normal differentiation. Catalase A is the major vegetative catalase which functions in removing hydrogen peroxide generated during the process of aerobic metabolism. To understand the regulatory mechanism of response against oxidative stress, hydrogen peroxide-resistant mutant (HR4O) was isolated from S. coelicolor J1501 following UV mutagenesis. The mutant overproduced catalase A more than 50-fo1d compared with the wild type. The mutation locus catRI was mapped closed to the mthB2 locus by genetic crossings. An ordered cosmid library of S. coelicolor encompassing the mthB2 locus was used to isolate the regulator gene (catR) which represses catalase overproduction when introduced into HR4O. A candidate catR gene was found to encode a Fur-like protein of 138 amino acids (15319 Da).

• Journal of Korean Society for Atmospheric Environment
• /
• 제23권E1호
• /
• pp.16-28
• /
• 2007

An improved method was developed to determine gas-phase hydrogen peroxide($H_2O_2$) and organic hydro-peroxides (ROOH) in real-time, The analytical system for $H_2O_2$ is based on formation of hydroxybenzoic acid (OHBA), a strong fluorescent compound. OHBA is formed by a sequence of reactions, photoreduction of Fe(III)-EDTA to Fe(II)-EDTA, the Fenton reaction of Fe(II)-EDTA with $H_2O_2$, and hydroxylation of benzoic acid. By use of this analytical method rather than a previous similar method, Fenton reaction time was reduced from 2 min. to 30s. Air samples were collected by a surfaceless inlet to prevent inlet line losses. With a special arrangement of the sampling apparatus, sample delivery time was drastically reduced from ${\sim}5\;min\;to\;{\sim}20\;s$. The automated system was found to be sensitive, capable of continuous monitoring, and affordable to operate. A comparison of this method with a well-established one showed an excellent linear correlation, validating applicability of this technique to $H_2O_2$ determination. The system was applied to field measurements conducted during summertime of 2004 in Gwangju, South Korea. $H_2O_2$ was found to be a predominant species of peroxides. The diurnal variation of $H_2O_2$ displayed the maximum in early afternoon and the broad minimum throughout night. $H_2O_2$ was correlated positively with ozone, photochemical age, and temperature, however, negatively with $NO_x$ and relative humidity.