• Title/Summary/Keyword: Cell membrane penetration

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Study on the Durability Characteristics of the PEM Fuel Cells having Gas Diffusion Layer with Different Micro Porous Layer Penetration Thicknesses (기체확산층의 미세다공층 침투 깊이에 따른 고분자 전해질형 연료전지의 내구성능 저하 분석에 관한 연구)

  • Park, Jaeman;Oh, Hwanyeong;Cho, Junhyun;Min, Kyoungdoug;Lee, Eunsook;Jyoung, Jy-Young
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.3
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    • pp.216-222
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    • 2013
  • Durability characteristics of Gas Diffusion Layer(GDL) is one of the important issues for accomplishing commercialization of Proton Exchange Membrane Fuel Cell(PEMFC). It is strongly related to the performances of PEMFC because one of the main functions of GDL is to work as a path of fuel, air and water. When the GDL does not work on their proposed functions due to the degradation of durability, mass transfer in PEMFC is disturbed and it might cause the flooding phenomenon. Thus, investigating the durability of GDL is important and understanding the GDL degradation process is needed. In this study, electrochemical degradation with carbon corrosion is introduced. The carbon corrosion experiment is carried out with GDLs which have different MPL penetration thicknesses. After the experiment, the amount of degradation of GDL is measured with various properties of GDL such as weight, thickness and performance of the PEMFC. The degraded GDL shows loss of their properties.

Synthesis and Antitumor Activity of 2',3'-Didehydro-3'-Didehydro-3'-deoxy-thymidine and Its Derivative

  • 이봉훈;임미경;신정희;장태식;박장수;강신원
    • Bulletin of the Korean Chemical Society
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    • v.18 no.7
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    • pp.711-714
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    • 1997
  • In an effort to enhance the lipophilicities, thereby, the penetration into the cell membrane and to increase the antitumor activities of modified derivatives of 2',3'-didehydro-3'-deoxythymidine (d4T, 1), derivatives of 1 were designed and synthesized. Starting from thymidine, 1, 2',3'-didehydro-3'-deoxythymidine-5'-phosphate, disodium salt (d4T-p, 7), and two nicotinate esters of 1; 2',3'-didehydro-3'-deoxy-5'-O-(3-pyridinylcarbonyl)thymidine (d4T-NA, 5) and 2',3'-didehydro-3'-deoxy-5'-phosphoryl-O-(3-pyridinylcarbonyl)thymidine (d4T-p-NA, 8) were synthesized. The lipophilicities of the synthesized compounds were measured by P-values and antitumor activities of those were estimated against mouse leukemia P388, murine mammary carcinoma FM3A, and human histiocytic lymphoma U937 tumor cells in vitro. Although the lipophilicities of the nicotinate esters, 5 and 8 were increased 2.75- and 9.71-fold relative to that of 1 and 7, respectively, the synthesized compounds, 1, 5, 7, and 8 were found to be inactive against P388 and FM3A cells except weak antitumor activity against U937 cell.

Phospholipase Activities in Clinical and Environmental Isolates of Acanthamoeba

  • Matin, Abdul;Jung, Suk-Yul
    • Parasites, Hosts and Diseases
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    • v.49 no.1
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    • pp.1-8
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    • 2011
  • The pathogenesis and pathophysiology of Acanthamoeba infections remain incompletely understood. Phospholipases are known to cleave phospholipids, suggesting their possible involvement in the host cell plasma membrane disruption leading to host cell penetration and lysis. The aims of the present study were to determine phospholipase activities in Acanthamoeba and to determine their roles in the pathogenesis of Acanthamoeba. Using an encephalitis isolate (T1 genotype), a keratitis isolate (T4 genotype), and an environmental isolate (T7 genotype), we demonstrated that Acanthamoeba exhibited phospholipase $A_2$ (PLA$_2$). and phospholipase D (PLD) activities in a spectrophotometry-based assay. Interestingly, the encephalitis isolates of Acanthamoeba exhibited higher phospholipase activities as compared with the keratitis isolates, but the environmental isolates exhibited the highest phospholipase activities. Moreover, Acanthamoeba isolates exhibited higher PLD activities compared with the PLA$_2$. Acanthamoeba exhibited optimal phospholipase activities at $37^{\circ}C$ and at neutral pH indicating their physiological relevance. The functional role of phospholipases was determined by in vitro assays using human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier. We observed that a PLD-specific inhibitor, i.e., compound 48/80, partially inhibited Acanthamoeba encephalitis isolate cytotoxicity of the host cells, while PLA$_2$-specific inhibitor, i.e., cytidine 5'-diphosphocholine, had no effect on parasite-mediated HBMEC cytotoxicity. Overall, the T7 exhibited higher phospholipase activities as compared to the T4. In contract, the T7 exhibited minimal binding to, or cytotoxicity of, HBMEC.

Electrochemical Activation of Nitrate Reduction to Nitrogen by Ochrobactrum sp. G3-1 Using a Noncompartmented Electrochemical Bioreactor

  • Lee, Woo-Jin;Park, Doo-Hyun
    • Journal of Microbiology and Biotechnology
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    • v.19 no.8
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    • pp.836-844
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    • 2009
  • A denitrification bacterium was isolated from riverbed soil and identified as Ochrobactrum sp., whose specific enzymes for denitrification metabolism were biochemically assayed or confirmed with specific coding genes. The denitrification activity of strain G3-1 was proportional to glucose/nitrate balance, which was consistent with the theoretical balance (0.5). The modified graphite felt cathode with neutral red, which functions as a solid electron mediator, enhanced the electron transfer from electrode to bacterial cell. The porous carbon anode was coated with a ceramic membrane and cellulose acetate film in order to permit the penetration of water molecules from the catholyte to the outside through anode, which functions as an air anode. A non-compartmented electrochemical bioreactor (NCEB) comprised of a solid electron mediator and an air anode was employed for cultivation of G3-1 cells. The intact G3-1 cells were immobilized in the solid electron mediator, by which denitrification activity was greatly increased at the lower glucose/nitrate balance than the theoretical balance (0.5). Metabolic stability of the intact G3-1 cells immobilized in the solid electron mediator was extended to 20 days, even at a glucose/nitrate balance of 0.1.

Transdermal Delivery of Porcine Placenta Extracts using Linolenic Acid-based Emulsion Formulations

  • Kim, Dong-Chan;Noh, Sang-Myoung;Park, Ki-Tae;Kim, Young-Bong;Baek, Kwang-Hyun;Oh, Yu-Kyoung
    • Journal of Pharmaceutical Investigation
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    • v.37 no.5
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    • pp.281-286
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    • 2007
  • For transdermal delivery of porcine placenta extract (PPE), various emulsion formulations were prepared and evaluated. Polysorbate surfactants were used as emulsifiers and various C-18 unsaturated fatty acids as enhancers. The skin permeation of PPE was tested using a cellulose nitrate membrane-loaded Franz cell apparatus. Among emulsifiers, Tween 20 provided higher penetration effect than did Tween 80. Meanwhile, of various fatty acids, linolenic acid (18:3) revealed the highest skin permeation of PPE than the other C-18 unsaturated fatty acids. Stability of PPE emulsions was determined by cycles of freezing and thawing processes. The stability of emulsions depended on the percentage of Tween 20. Minimum 20% of Tween 20 was required to stabilize emulsions at room temperature for several days. Taken together, our results suggest that Tween 20 and linolenic acids might be key components to formulate PPE emulsion to provide the desirable skin permeability and stability.

Studies on Improving Preservative Treatability of Japanese Larch Heartwood by Presteaming (증기(蒸氣) 전처리(前處理)에 의(依)한 낙엽송(落葉松) 심재(心材)의 방부제(防腐劑) 처리도(處理度) 개선(改善)에 관(關)한 연구(硏究))

  • Kang, Sung-Mo;Paik, Ki-Hyon;Kim, Gyu-Hyeok
    • Journal of the Korean Wood Science and Technology
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    • v.25 no.1
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    • pp.15-22
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    • 1997
  • The effectiveness of presteaming for improving CCA treatability on refractory Japanese larch heartwood was investigated in this study. Presteaming was effective on improving treatability, and the extent of improvement was dependent on moisture contents of wood specimen and steaming conditions. Green wood showed higher average value in both preservative retention and penetration than dry wood, and steaming under pressure conditions also had higher treatability than steaming at atmospheric conditions. The degree of improvement for treatability was increased with the extension of steaming period. Treatability of dry wood pres teamed under pressure conditions more than 6 hours and green wood for 3 hours was similar to that enhanced by conventional incising. Presteaming green wood under pressure conditions more than 6 hours was more effective than conventional incising in improvement of CCA treatability, and resultant treatability satisfied a minimum value required for CCA-treated wood for being used at the regions of hazard class H3 and H4. In addition, an improvement of treatability by presteaming was due to an increase in permeability resulted from the degradation of hemicelluloses within aspirated pit membrane and cell wall, not the removal of extractives from pit membrane. The reduction in strength, measured as longitudinal compressive strength, due to pres teaming was related with the degradation of hemicelluloses, and was increased as steaming conditions were severe. The degree of strength reduction associated with presteaming treatment to obtain required treatability could be quantified from the relatively good relation between the increase in treatability and the decrease in strength.

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Gallic acid-mitochondria targeting sequence-H3R9 induces mitochondria-targeted cytoprotection

  • Bae, Yoonhee;Kim, Goo-Young;Jessa, Flores;Ko, Kyung Soo;Han, Jin
    • The Korean Journal of Physiology and Pharmacology
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    • v.26 no.1
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    • pp.15-24
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    • 2022
  • The development of selective targeting of drug molecules towards the mitochondria is an important issue related to therapy efficacy. In this study, we report that gallic acid (GA)-mitochondria targeting sequence (MTS)-H3R9 exhibits a dual role as a mitochondria-targeting vehicle with antioxidant activity for disease therapy. In viability assays, GA-MTS-H3R9 showed a better rescue action compared to that of MTS-H3R9. GA-MTS-H3R9 dramatically exhibited cell penetration and intercellular uptake compared to MTS and fit escape from lysosome release to the cytosol. We demonstrated the useful targeting of GA-MTS-H3R9 towards mitochondria in AC16 cells. Also, we observed that the antioxidant properties of mitochondrial-accrued GA-MTS-H3R9 alleviated cell damage by reactive oxygen species production and disrupted mitochondrial membrane potential. GA-MTS-H3R9 showed a very increased cytoprotective effect against anticancer activity compared to that of MTS-H3R9. We showed that GA-MTS-H3R9 can act as a vehicle for mitochondria-targeting and as a reagent for therapeutic applications intended for cardiovascular disease treatment.

UV-cured Polymer Solid Electrolyte Reinforced using a Ceramic-Polymer Composite Layer for Stable Solid-State Li Metal Batteries

  • Hye Min Choi;Su Jin Jun;Jinhong Lee;Myung-Hyun Ryu;Hyeyoung Shin;Kyu-Nam Jung
    • Journal of Electrochemical Science and Technology
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    • v.14 no.1
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    • pp.85-95
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    • 2023
  • In recent years, solid-state Li metal batteries (SSLBs) have attracted significant attention as the next-generation batteries with high energy and power densities. However, uncontrolled dendrite growth and the resulting pulverization of Li during repeated plating/stripping processes must be addressed for practical applications. Herein, we report a plastic-crystal-based polymer/ceramic composite solid electrolyte (PCCE) to resolve these issues. To fabricate the one-side ceramic-incorporated PCCE (CI-PCCE) film, a mixed precursor solution comprising plastic-crystal-based polymer (succinonitrile, SN) with garnet-structured ceramic (Li7La3Zr2O12, LLZO) particles was infused into a thin cellulose membrane, which was used as a mechanical framework, and subsequently solidified by using UV-irradiation. The CI-PCCE exhibited good flexibility and a high room-temperature ionic conductivity of over 10-3 S cm-1. The Li symmetric cell assembled with CI-PCCE provided enhanced durability against Li dendrite penetration through the solid electrolyte (SE) layer than those with LLZO-free PCCEs and exhibited long-term cycling stability (over 200 h) for Li plating/stripping. The enhanced Li+ transference number and lower interfacial resistance of CI-PCCE indicate that the ceramic-polymer composite layer in contact with the Li anode enabled the uniform distribution of Li+ flux at the interface between the Li metal and CI-PCCE, thereby promoting uniform Li plating/stripping. Consequently, the Li//LiFePO4 (LFP) full cell constructed with CI-PCCE demonstrated superior rate capability (~120 mAh g-1 at 2 C) and stable cycle performance (80% after 100 cycles) than those with ceramic-free PCCE.

The Application of Nanoliposome Composed of Ceramide as an Anti-irritant in Cosmetics (세라마이드를 구성성분으로 하는 나노리포좀의 응용 - 화장품에서의 자극완화제)

  • Jo Byoung Kee;Ahn Gi Woong;Shin Bong Soo;Jeong Ji Hean;Park Hae-Ryong;Hwang Yong-Il
    • Journal of Life Science
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    • v.15 no.2 s.69
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    • pp.267-272
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    • 2005
  • The objective of this study is to suggest the potentialities of nanoliposome composed of ceramide as an anti-irritant against various irritants used in cosmetics. Ceramides are major structural components of the epidermal permeability barrier, which is known to play an essential part in human physiology by not only preventing the loss of water from the body but also protecting the body from external physical, chemical, and microbial insults. According to the results, better effects on reinforcement of skin barrier function and anti-irritation were obtained with nanoliposome composed of ceramide than with dispersed ceramide. And, we performed in vitro skin penetration test using horizontal Franz diffusion cells with skin membrane prepared from hairless mouse to evaluate the influence of nanoliposome composed of ceramide on the skin penetration of lactic acid in formulations. From the results, we found that the anti-irritation effects of nanoliposome containing ceramide were due to reduced penetration rate of irritants. Conclusively, we could develop a new anti-irritation system and apply this nanoliposome composed of ceramide to the final cosmetic products successfully.

Effects of Sayeok-tang on Papain-Induced Osteoarthritis in Mice (Papain으로 유도된 골관절염 생쥐 모델에서 사역탕(四逆湯)의 항골관절염 효능에 관한 연구)

  • Kung, Shyang En;Oh, Min Seok
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.27 no.2
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    • pp.212-224
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    • 2013
  • This study intends to clarify how Sayeok-tang(here in after reffered to SYT) affect C57BL/10 mice whose osteoarthritis was induced by papain. Osteoarthritis was induced by injecting papain in the knee joint of 3 groups(n=6) of mice. Normal group was non-treatment group and was not injected papain, whereas control mice were orally administered with $200{\mu}{\ell}$ of physiological saline. Positive comparison group was medicated with 100 mg/kg of Joins$^{(R)}$ mixed with $200{\mu}{\ell}$ of physiological saline. Experimental group was medicated with 400 mg/kg of SYT mixed with $200{\mu}{\ell}$ of physiological saline. Both Positive and experimental comparison groups were orally medicated once per day for 4 weeks. After the experiment, the functions of liver and kidney, inflammation cytokine values within serum, degree of revelation for inflammation cytokine genes, immune cells within blood, metabolism of arachidonic acid and amount of cartilage were measured and histopathological changes in the knee joint structures were observed. As results, SYT had no significant effect on the liver and kidney functions. Interleukin-$1{\beta}$(IL-$1{\beta}$), interleukin-6(IL-6), monocyte chemo attractant protein-1(MCP-1) and tumor necrosis factor-${\alpha}$(TNF-${\alpha}$) were significantly decreased. Inflammation cytokines in joints were all significantly decreased. Prostaglandin $E_2(PGE_2)$, thromboxane $B_2(TXB_2)$ were significantly decreased. Destruction of cartilage on micro computed tomography(CT)-arthrography was meaningfully decreased. In terms of histopathology, infiltration of inflammation, proliferation of synovial membrane, subsidence of cartilage and bone due to penetration of excessive formation of synovial cell and destruction of cartilage were small. Based on all results mentioned above, Sayeok-tang(SYT) is believed to be meaningful for suppressing the progress of osteoarthritis and its treatments because of its anti-inflammatory effects and alleviation of pain with histopathological effective efficacy.