• Applied Biological Chemistry
• /
• 제47권3호
• /
• pp.293-299
• /
• 2004

거대배아미 에탄올 추출물의 항산화활성을 지질과산화 억제활성 및 활성산소종의 소거활성을 중심으로 일반미와 대조하여 검토하였다. 연구 결과, 발아처리는 전반적으로 환원력 및 지질과산화 억제활성, superoxide radical 및 hydroxyl radical 소거활성을 상승시켰으며, 발아처리에 의한 항산화 활성의 증가현상이 화청거대배아미에서 가장 뚜렷하였다. Superoxide radical 소거작용에 있어서는 남풍거대배아미가 전체적인 소거활성은 높았으나, 발아처리에 의한 활성의 상승률은 역시 화청거대배아미가 가장 높았고, 그 작용기작은 시료에 의한 직접적인 radical 소거에 있는 것으로 나타났다. 생체 독성이 가장 큰 hydroxyl radical 소거활성을 조사한 결과, 화청거대배아미가 전체적인 소거활성 뿐 아니라, 발아처리에 의한 소거활성의 증가율도 가장 높았으며, 그 작용기작도 $Fe^{2+}$의 포족이 아닌 직접적인 라디칼 소거임이 밝혀졌다. 이와 같은 in vitro에서 관찰된 시료의 ROS 소거활성은 TPA하여 유도된 HL-60 세포의 ROS 생산을 억제하는데 유효하게 작용하였다.

• 대한수학회보
• /
• 제44권2호
• /
• pp.331-336
• /
• 2007

We consider infinite nested radicals in which the arguments are positive polynomial sequences. It is shown that the evaluation of such a nesting is always finite, and we prove necessary and sufficient conditions for the evaluation to be a finite polynomial.

• 한국환경성돌연변이발암원학회:학술대회논문집
• /
• 한국환경성돌연변이발암원학회 2004년도 춘계학술대회
• /
• pp.85-85
• /
• 2004

• Korean Journal of Acupuncture
• /
• 제22권4호
• /
• pp.57-65
• /
• 2005

대계는 전통 한의학에서 약용 물질로 널리 쓰이고 있으므로, 대계의 약침을 조제하여 항산화적 활성을 검증해 보았다. 실험의 재료로 쓰인 대계는 동국대학교 한의과대학 부속 한방 병원에서 구입하여 사용하였고 (경상북도 경주), 이를 약침액으로 조제한 후 동결 건조 방법으로 5.1 %의 분말을 회수 하였다. 대계 약침액의 항산화 능력을 측정하기 위하여 DPPH자유기의 소거능은 Gyamfi et al. 의 방법을 따랐고, superoxide radicals $(O_2^-{\cdot})$ 소거능은 Gotoh et al.의 방법을 일부 수정하여 사용하였다. Hydroxyl radicals의 직접적인 소거능과 iron ions 사이의 관계는 deoxyribose assay를 통하여 검증하였다. 이상의 실험 결과에서 1) Non-site-specific scavenging assay (hydroxyl radicals, OH) 및 2) Site-specific scavenging assay (chelate iron ions) 그리고 3) 전산화 효과에서 모두 대계 약침액은 농도 의존적인 저해 효과를 보였으며, 특히 pro-oxidant 실험에서는 산화를 촉진하지 않는 것으로 나타났다. 끝으로 hydorxyl radical에 의하여 매개되는 DNA의 분절 효과를 적절하게 방어하는 것을 관찰할 수 있었다. 따라서 대계 약침액은 산화적 스트레스를 직접적으로 방어 하고, 다양한 산화적 손상에 의한 병증을 예방할 것으로 사료된다.

• 한국자동차공학회논문집
• /
• 제12권2호
• /
• pp.45-53
• /
• 2004

An experimental study was carried out to obtain the fundamental data about the effects of radicals induced injection on premixture combustion. A constant volume combustor divided to the sub-chamber and the main chamber was used. The volume of the sub-chamber is set up to occupy less than 1.5％ of that of whole combustion chamber. Radial twelve narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in the sub-chamber will derive the simultaneous multi-point ignition in the main chamber. While the equivalence ratio of pre-mixture in the main chamber and the sub-chamber is uniform. We have examined the effects of the sub-chamber volume, the diameter of passage hole, and the equivalence ratio on the combustion characteristics by means of burning pressure measurement and flame visualization. In the case of radical ignition method(RI), the overall turning time including the ignition delay became very short and the maximum burning pressure was slightly increased in comparison with those of the conventional spark ignition method(SI), that is, single chamber combustion without the sub-chamber. The combustible lean limit by RI method is extended to more ER=0.25 than that by SI method. Therefore the decrease of every emission including NOx and the improvement of fuel consumption is anticipated due to lean burn.

• Toxicological Research
• /
• 제14권3호
• /
• pp.301-306
• /
• 1998

This experiment was carrid out to know the effects of heating and serum on hydroxyl radicals in embryonic mouse forebrain (cerebrum) culture. The heating to mouse embryonic cerebrum cells in culture was done in a water bath at 43${\circ}C$ for 60min. After that, two supernatants were prepared at 20 hrs and 48 hrs respectively after heat treatment to the brain cells. To find out the heating effects on neuron cells, mouse cerebrum cells (13 embryonic day) were cultured in hydroxyl radical generation system composed of 20mU/ml glucose oxidase (GO system), using condition of normal culture media (MEM, 5% serum, 5% $CO_2$or supernatant prepared after heating at 43${\circ}C$ for 60 min in a water bath. Supernatant prepared at 20 hrs after heat treatment had a greater protective effects against hydroxyl radical than supernatant prepared at 48 hrs after heat treatment . Otherwise, the protective effect of serum against hydroxyl radicals in the cultured brain cells is higher than that in the heat treatment. These results indicated that serum in culture media reduced cytotoxicity of hydroxyl radicals in mouse forebrain culture, also that heat treatment showed the protective effects against hydroxyl radicals generated with 20mU/ml GO system in mouse forebrain culture.

• The Korean Journal of Physiology and Pharmacology
• /
• 제2권5호
• /
• pp.629-635
• /
• 1998

It has been suggested that oxygen free radicals are involved in the initiation process of acute pancreatitis, although its pathogenesis is not clear. This study evaluates the roles of oxygen radicals and the effects of small molecular antioxidants (rebamipide, N-acetyl-cysteine, allopurinol, ${\beta}-carotene)$ on the development of cerulein-induced acute pancreatitis. Acute edematous pancreatitis was induced by the intravenous infusion of cerulein at supramaximal dose of 10 ${\mu}g/kg/hour$ for 3.5 hours. The effects of antioxidants, rebamipide (100 mg/kg, i.p.), N-acetyl-cysteine (200 mg/kg, i.v.), allopurinol (20 mg/kg/hour), ${\beta}-carotene$ (50 mg/kg, i.p.), were examined. Cerulein administration resulted in a significant increase in serum amylase activity and pancreatic malondialdehyde (MDA), but not glutathione peroxidase (GSHpx). The glutathione (GSH) content in pancreatic tissue decreased dramatically. Pretreatment of N-acetyl-cysteine significantly decreased the cerulein-induced hyperamylasemia and maintained GSH content in pancreas, but MDA was slightly decreased. In addition, N-acetyl-cysteine ameliorated histological damage. Allopurinol and ${\beta}-carotene$ attenuated cerulein-induced hyperamylasemia, but histologically there was no difference from control. These results indicate that oxygen free radicals play an important role in the initiation of experimental acute pancreatitis. N-acetyl-cysteine is an effective antioxidant that ameliorates the cerulein-induced acute pancreatitis, and the possible therapeutic application of antioxidants against acute pancreatitis needs a further evaluation.

• Journal of Preventive Medicine and Public Health
• /
• 제23권4호
• /
• pp.371-390
• /
• 1990

Production of free radicals of superoxide anion in tissues by cadmium, activities of superoxide dismutase and catalase to protect tissue damages caused by the free radicals and ATPase that plays an important role in energy metabolism at cellular level were investigated. Experiments in vivo were conducted with liver, kidney and testicle tissue homogenates of rats adding $0.05{\sim}0.50mM$ cadmium chloride, and in vivo experiments administering single dose of 5 mg of cadmium/kg of body weight in 0.1% cadmium chloride solution intraperitoneally 48 hours prior to evisceration. Production of superoxide radicals in liver and testicle increased with addition of cadmium in vitro, but not in kidney. In vivo experiments, however, superoxide radicals slightly increased in liver and kidney but not in testicle. Superoxide dismutase (Cu, Zn-SOD and Mn-SOD), catalase and ATPase (total, $Mg^{++}-\;&\;Na^+,\;K^+-$) activity decreased in the presence of cadimium in dose dependent manner. Reduction of these enzyme activities varied not only with dosage of cadmium but also with type of tissue and between in vitro and in vivo experiment.

• 한국식품영양학회지
• /
• 제29권6호
• /
• pp.829-834
• /
• 2016

Free radicals originate due to the radiolysis of cytoplasmic water with low "Linear Energy Transfer" (LET) radiations. Naringenin (Ng) is a natural antioxidative compound found in citrus fruits. This study revealed that Naringenin (Ng) reduced the radiation damage of critical organs by scavenging oxidative free radicals. In the study, Ng was orally administrated to rats daily for 7 consecutive days, prior to whole body exposure to gamma-rays. The scavenging efficacy was evaluated biochemically by measuring the concentration of cytotoxic byproducts and the activity of enzymes relevant to oxidative free radicals, after extracting the organs from the exposed rat. We observed increased levels of malondialdehyde (MDA) concentration, and decrease in the activities of superoxide dismutase (SOD) and catalase (CAT) in the exposed control group. However, pretreatment with Ng significantly reduced the MDA concentration, and increased the activities of SOD and CAT, as compared to the control group, due to the free radical scavenging by Ng. The results indicate that Ng administration prior to irradiation could protect critical organs from radiation damage.

• 대한기계학회논문집B
• /
• 제24권6호
• /
• pp.769-776
• /
• 2000

Visible spectral characteristics of cross-sectional emissions from a partially premixed methane/air and propane/air flames have been investigated. An optical train with a two-axis scanning mirror system was used to record line-of-sight emission spectra from 354nm to 618nm, and inversion technique was adapted to obtain cross-sectional emission spectra. By analyzing the reconstructed emission spectra, cross-sectional intensities of CH and $C_2$ radicals were separated from the background emissions. The blue flame edge and yellow flame edge were also obtained by image processing technique for edge detection with color photograph of flame. These edges were compared with radial distributions of CH, $C_2$ radicals and background emissions. The CH radicals were observed at blue flame edge. The background emissions were generated by soot precursor at upstream of flame and by soot at downstream of flame. The $C_2$ radicals in propane/air flame were observed more than those in methane/air flame.