• Tuberculosis and Respiratory Diseases
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• v.78 no.3
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• pp.149-155
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• 2015

Extracorporeal life support (ECLS) is a type of cardiopulmonary bypass. It is an artificial means of supplying oxygen and removing $CO_2$ on behalf of damaged lungs while patients are recovering from underlying diseases. Recently, the use of ECLS is rapidly increasing as this machine becomes smaller, less invasive and easier to use. In addition, the improvement of clinicians' technique and outcome is increasing their application to patients with acute respiratory distress. In this regard, the purpose of this review is to introduce the physiological principles, risk factors, and advantages of ECLS, clinical rationale for using ECLS, ventilatory strategy during ECLS, which are still causing different opinions, the weaning from ECLS, and the use of anticoagulant.

• BMB Reports
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• v.45 no.4
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• pp.242-246
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• 2012

The use of ionizing radiation (IR) is essential for treating many human cancers. However, radioresistance markedly impairs the efficacy of tumor radiotherapy. IR enhances the production of reactive oxygen species (ROS) in a variety of cells which are determinant components in the induction of apoptosis. Much interest has developed to augment the effect of radiation in tumors by combining it with radiosensitizers to improve the therapeutic ratio. In the current study, the radiosensitizing effects of resveratrol and piperine on cancer cells were evaluated. Cancer cell lines treated with these natural products exhibited significantly augmented IR-induced apoptosis and loss of mitochondrial membrane potential, presumably through enhanced ROS generation. Applying natural products as sensitizers for IR-induced apoptotic cell death offers a promising therapeutic approach to treat cancer.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.456-461
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• 2003

A fuel cell is an electrochemical device in which the energy of a chemical reaction is converted directly into electricity. By combining hydrogen fuel with oxygen from air, electricity is formed, without combustion of any form. Water and heat are the only by-products when hydrogen is used as the fuel source. Fuel cell stack consists of multi-layered unit cells. A unit cell consists of MEA and bipolar plates. The end plate of fuel cell stack should give a uniform distributed pressure to multi unit cell layers so as to reduce the contact resistance and to prevent the leakage of reactant gases and the damage of multi layer components. The current end plate is redundantly large and heavy. It makes the power per unit volume reduced. Topology optimization of end plate is conducted for mass reduction and enhancement of bending rigidity. The evaluation of the current design and the recommendation for the future design is remarked.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.21-22
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• 2001

Phospholipase A$_2$(PLA$_2$) comprise a family of enzymes that hydrolyze the acyl bond at the sn-2 position of phospholipids to generate free fatty acids including arachidonic acid and lysophospholipids. Distinct forms of PLA$_2$are involved in digestion, inflammation, and intercelluar-and intracellular signaling pathways. The released arachidonic acid, which is enriched at the sn-2 position, serves as the precursor for eicosanoids such as prostaglandins and leukotrienes. During oxygenation of arachidonic acid to hydroxy endoperoxide, reactive oxygen radicals are generated. On the other hand, lysophospholipids increase membrane fluidity and can be cytotoxic with its detergent-like action. Thus, the biochemical features of the products of PLA$_2$activity suggest that PLA$_2$may be implicated in many destructive cellular processes.

• Korean Journal of Pharmacognosy
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• v.51 no.1
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• pp.30-35
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• 2020

We previously reported that caffeic acid isolated from Lonicera japonica showed potent neuroprotective activities against glutamate injured neuronal cell death in primary cortical cells. In this study, we tried to confirm the neuroprotective activity in glutamate injured HT22 cells and elucidate mechanisms of neuroprotective action of caffeic acid. We used glutamate induced HT22 cell death as a bioassay system. The compound decreased reactive oxygen species increased by high concentration of glutamate treatment in HT22 cells. Also, Ca²⁺ concentration was decreased by this compound. This compound made mitochondrial membrane potential maintain to normal condition. This also affected anti-oxidative enzymes and glutathione contents. Treatment of this compound increased not only glutathione reductase and peroxidase to the control level and also amount of glutathione, an endogeneous antioxidant. These experimental results showed that caffeic acid isolated from L. japonica exerted potent neuroprotective activity through the anti-oxidative pathway.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.373-380
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• 2020

This study was carried out to convert the hydrophobic characteristics of PVDF to hydrophilic. Poly(-vinylidene fluorine) (PVDF) was grafted by electron beam irradiation and sulfonated. The grafting degree of modified PVDF increased with the monomer concentration, but not the conversion degree. From the results of FTIR and XPS, it was shown that the amount of converted sulfur increased with the grafting degree. The radiation-induced graft polymerization led to decrease fluorine from 35.7% to 21.3%. Meanwhile, the oxygen and sulfur content increased up to 8.1% and 3.2%. The pore size of modified membranes was shrunken and the roughness sharply decreased after irradiation. The ion exchange capacity and contact angle were investigated to show the characteristics of PVDF. The enhanced ion exchange capacity and lower contact angle of modified PVDF showed that the hydrophilicity played a role in determining membrane fouling. Electron beam irradiation successfully modified the hydrophobic characteristics of PVDF to hydrophilic.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.175-186
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• 2004

In this paper, we developed the dynamic model of a fuel cell system suitable for controller design and system operation. The transient phenomena captured in the model include the flow characteristics and inertia dynamics of the compressor, the intake manifold filling dynamics, oxygen partial pressures and membrane humidity on the fuel cell voltage. In the simulations, we paid attention to the transient behavior of stack voltage and compressor pressure, stoichiometric ratio. Simulation results are presented to demonstrate the model capability. For load current following, stack voltage dynamic characteristics are plotted to understand the Electro-chemistry involved with the fuel cell system. Compressor pressure and stoichiometric ratio are strongly coupled, and independent parameters may interfere with each other, dynamic response, undershoot and overshoot.

• CELLMED
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• v.2 no.1
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• pp.2.1-2.11
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• 2012

Tea polyphenols especially catechins have long been studied for their antioxidant and radical scavenging properties. Scientists throughout the world have investigated the usefulness of the regular green tea consumption in several disease conditions. In-vitro and in-vivo experiments on catechins especially epigallocatechingallate have revealed a significant role in many ways. Reactive oxygen species have been increasingly implicated in the pathogenesis of many diseases and important biological processes. Toxic effects of these oxidants, commonly referred to as oxidative stress, can cause cellular damage by oxidizing nucleic acids, proteins, and membrane lipids. Oxidative stress has been related to aging and age related disorders. It is found that in a wide variety of pathological processes, including cancer, atherosclerosis, neurological degeneration, Alzheimer's disease, ageing and autoimmune disorders, oxidative stress has its implications. Catechins have been reported to be useful in combating aging and age related disorders like cancer, cardiovascular disorders and neurodegenerative diseases. In this mini review we will discuss such studies done across the globe.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.250-250
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• 2002

This study confirmed that white rot fungus Irpex lacteus was able to metabolize 2,4,6-trinitrotoluene (TNT) with two different initial transformations. In one metabolic pathway of TNT a nitro group was removed from the aromatic ring of TNT. Hydride-Meisenheimer complexes of TNT (H/sup -/-TNT), colored dark redo were confirmed as the intermediate in this transformation by comparison with the synthetic compounds. 2,4-Dinitrotoluene as a following metabolic product was detected, and nitrite produced by denitration of $H^-$-TNT supported this transformation. In the other TNT pathway, nitro groups in TNT were successively reduced to amino groups via hydroxylamines. Hydroxylamino-dinitrotoluenes and amino-dinitrotoluenes were identified as the intermediates. The activity of a membrane-associated aromatic nitroreductase was detected in the cell-free extract of I. lacteus. This enzyme catalyzed the nitro group reduction of TNT with NADPH as a cofactor, Enzyme activity was not observed in the presence of molecular oxygen.

• Toxicological Research
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• v.33 no.3
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• pp.233-238
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• 2017

Xylene is a cyclic hydrocarbon and an environmental pollutant. It is also used in medical technology, paints, dyes, polishes and in many industries as a solvent; therefore, an understanding of the interaction between xylene and human lymphocytes is of significant interest. Biochemical assessment was used to demonstrate that exposure of lymphocytes to xylene induces cytotoxicity (at 6 hr), generates intracellular reactive oxygen species, collapse of mitochondrial membrane potential, lysosomal injury, lipid peroxidation and depletion of glutathione (at 3 hr). The findings show that xylene triggers oxidative stress and organelle damage in lymphocytes. The results of our study suggest that the use of antioxidant, mitochondrial and lysosomal protective agents can be helpful for individuals subject to chronic exposure to xylene.