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Lee, Kyung Ah,Yoon, Ki Ro,Kwon, Sung Hyun,Lee, Kyung Jin,Jo, Sunhee,Lee, Ju Sung,Lee, Kwan-Young,Lee, Seung Woo,Lee, Seung Geol,Kim, Jin Young The Royal Society of Chemistry 2019 Journal of materials chemistry. A, Materials for e Vol.7 No.13
<P>Self-assembly of inter- and intraphases between the ionomer membrane and mechanical reinforcements in reinforced polymeric composite membranes is of great interest in both physics and chemistry, particularly for proton exchange membrane fuel cell (PEMFC) application. One of the greatest challenges is to obtain an optimally structured polytetrafluoroethylene (PTFE)-reinforced perfluorosulfonic acid (PFSA) composite membrane <I>via</I> solution processing. For high- performance and durable PEMFC applications, the self-assembly of interphases of the ionomers/reinforcements and intraphases of the ionomers in the composite PEM needs to be carefully tailored. Here, we show that post-assembly modification of a PTFE/PFSA composite membrane using a spin-drying method can significantly improve fuel cell performance and reliability. The forced assembly of PFSA ionomers during spinning results in greater infiltration yields into the porous PTFE media. In this way, spin-drying post-treatment results in lower gas crossover and improved mechanical durability. This process also yields larger regions of ionic clusters, which facilitate proton conduction at low relative humidity, affording higher fuel cell currents and greater efficiency.</P>
Lee, Sunhee,Jeon, Eunyoung,Jung, Yeontae,Lee, Jinwon Humana Press 2012 Applied biochemistry and biotechnology Vol.167 No.1
<P>The goal of the present study was to increase the content of intracellular long-chain fatty acids in two bacterial strains, Pseudomonas aeruginosa PA14 and Escherichia coli K-12 MG1655, by co-overexpressing essential enzymes that are involved in the fatty acid synthesis metabolic pathway. Recently, microbial fatty acids and their derivatives have been receiving increasing attention as an alternative source of fuel. By introducing two genes (accA and fabD) of P. aeruginosa into the two bacterial strains and by co-expressing with them the fatty acyl-acyl carrier protein thioesterase gene of Streptococcus pyogenes (strain MGAS10270), we have engineered recombinant strains that are efficient producers of long-chain fatty acids (C16 and C18). The recombinant strains exhibit a 1.3-1.7-fold increase in the production of long-chain fatty acids over the wild-type strains. To enhance the production of total long-chain fatty acids, we researched the carbon sources for optimized culture conditions and results were used for post-culture incubation period. E. coli SGJS17 (containing the accA, fabD, and thioesterase genes) produced the highest content of intracellular total fatty acids; in particular, the unsaturated fatty acid content was about 20-fold higher than that in the wild-type E. coli.</P>
Lee, Sunhee,Jung, Yeontae,Lee, Seunghan,Lee, Jinwon Humana Press 2013 Applied biochemistry and biotechnology Vol.169 No.5
<P>Microorganisms have been used for biodiesel (fatty acid methyl ester) production due to their significant environmental and economic benefits. The aim of the present research was to develop new strains of Escherichia coli K-12 MG1655 and to increase the content of long-chain fatty acids by overexpressing essential enzymes that are involved in the fatty acid synthase elongation cycle. In addition, the relationship of β-ketoacyl-acyl carrier protein (ACP) synthase (fabH), β-ketoacyl-ACP reductase (fabG), β-hydroxyacyl-ACP dehydrase (fabZ), and β-enoyl-ACP reductase (fabI) with respect to fatty acid production was investigated. The four enzymes play a unique role in fatty acid biosynthesis and elongation processes. We report the generation of recombinant E. coli strains that produced long-chain fatty acids to amounts twofold over wild type. To verify the results, NAD(+)/NADH ratios and glucose analyses were performed. We also confirmed that FabZ plays an important role in producing unsaturated fatty acids (UFAs) as E. coli SGJS25 (overexpressing the fabZ gene) produced the highest percentage of UFAs (35 % of total long-chain fatty acids), over wild type and other recombinants. Indeed, cis-9-hexadecenoic acid, a major UFA in E. coli SGJS25, was produced at levels 20-fold higher than in wild type after 20 h in culture. The biochemically engineered E. coli presented in this study is expected to be more economical for producing long-chain fatty acids in quality biodiesel production processes.</P>
Lee, Han-Hyoung,Lee, Suk Jun,Kim, Sunhee,Jeong, Seonah,Na, Manheum,Lee, Dong-Mok,Cheon, Yong-Pil,Lee, Ki Ho,Choi, Inho,Chun, Taehoon Kluwer Academic Publishers 2012 Biotechnology letters. Vol.34 No.7
<P>Since T cells express diverse sex steroid hormone receptors, they might be a good model to evaluate the effects of sex steroid hormones on immune modulation. Porcine testicular extract contains several sex steroid hormones and may be useful to study the effects of sex steroid hormones during T cell activation. We have examined the effects of the porcine testicular extract on T cell activation: proliferation and secretion of cytokines (IL-2 and IFN-관) by activated T cells were severely decreased after treatment with porcine testicular extract. The extract produced an immunosuppressive effect and inhibited the proliferation of activated T cells by blocking the cell cycle transition from the G(1) phase to S phase. These effects were mediated by a decrease in the expression of cyclin D1 and cyclin E and constitutive expression of p27(KIP1) after T cell activation.</P>
Exploration of New Electroacupuncture Needle Material
Lee, Sanghun,Choi, Gwang-Ho,Lee, Chang Hoon,Kim, Yu Kyoung,Lee, Saebhom,Cho, Sungjin,Yeon, Sunhee,Choi, Sun-Mi,Ryu, Yeon-Hee Hindawi Publishing Corporation 2012 Evidence-based Complementary and Alternative Medic Vol.2012 No.-
<P><I>Background</I>. Electro Acupuncture (EA) uses the acupuncture needle as an electrode to apply low-frequency stimulation. For its safe operation, it is essential to prevent any corrosion of the acupuncture needle. <I>Objective</I>. The aim of this study is to find an available material and determine the possibility of producing a standard EA needle that is biocompatible. <I>Methods</I>. Biocompatibility was tested by an MTT assay and cytotoxicity testing. Corrosion was observed with a scanning electron microscope (SEM) after 0.5 mA, 60 min stimulation. The straightness was measured using a gap length of 100 mm, and tensile testing was performed by imposing a maximum tensile load. <I>Results</I>. Phosphor bronze, Ni coated SS304, were deemed inappropriate materials because of mild-to-moderate cytotoxicity and corrosion. Ti-6Al-4V and SS316 showed no cytotoxicity or corrosion. Ti-6Al-4V has a 70 times higher cost and 2.5 times lower conductivity than SS316. The results of both straightness and tensile testing confirmed that SS316 can be manufactured as a standard product. <I>Conclusion</I>. As a result, we confirmed that SS316 can be used a new EA electrode material. We hope that a further study of the maximum capacity of low-frequency stimulation using an SS316 for safe operation.</P>
Lee, Sunhee,Son, Kyu-Yeol,Noh, Yun-Hee,Lee, Seung-Chul,Choi, Hwan-Won,Yoon, In-Joong,Lee, Changhee Elsevier 2017 Veterinary microbiology Vol.207 No.-
<P><B>Abstract</B></P> <P>Porcine epidemic diarrhea virus (PEDV) has emerged or re-emerged worldwide, posing a significant financial threat to major pig-producing countries. In the present study, a virulent Korean pandemic PEDV strain, KNU-141112, was serially propagated in Vero cells for up to 100 passages. Through cell culture adaptation, we obtained four distinct deletion (DEL) mutants by plaque purification followed by nucleotide sequencing of the spike (S)/ORF3 gene-coding region, which were designated KNU-141112-S DEL2, −S DEL5, −S DEL2/ORF3, and −S DEL5/ORF3. Further whole genome sequencing identified 12 or 14 amino acid changes in the cell-adapted DEL strains. Animal inoculation studies revealed that the virulence of both S DEL2/ORF3 and S DEL5/ORF3 viruses with a large 46-nt deletion in the intergenic portion of S and ORF3 was remarkably diminished, indicating viral attenuation in the natural host. Furthermore, these cell-adapted strains elicited potent neutralizing antibody responses in immunized pigs. Taken together, our data indicate that the cell-attenuated S DEL2/ORF3 and S DEL5/ORF3 strains are promising candidates for the development of a safe and effective live PEDV vaccine.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A virulent G2b PEDV strain KNU-141112 was subjected to Vero cell culture passage. </LI> <LI> Deletions (DEL) in S and ORF3 of KNU-141112 at high passage levels were identified. </LI> <LI> Cell-adapted KNU-141112 DEL strains were highly attenuated and immunogenic in pigs. </LI> <LI> Large deletions in ORF3 appear to be associated with PEDV attenuation in pigs. </LI> <LI> High-cell-passage KNU-141112 DEL strains can be live, attenuated vaccine candidates. </LI> </UL> </P>
Effects of Forest/Thermal Combined Therapy for Smokers on Anxiety and Stress
Sunhee Lee,Youngran Chae 한국간호과학회 2021 한국간호과학회 학술대회 Vol.2021 No.10
Aim(s): Smoking can be a means of coping with anxiety and stress. The purpose of this study is to identify the effects on anxiety and stress by applying forest/thermal combined therapy for smokers with willingness to quit smoking. Method(s): A total of 30 participants were included in the study, 15 in the experimental group and 15 in the control group. Experimental subjects participated in the three-day forest/thermal combined therapy program. The program consisted of walking and meditation in the forest, thermal therapy in the charcoal kiln. Before and after the program, physiological indicators such as cortisol, heart rate variability and serotonin were measured together with the self-report questionnaires for anxiety (State-Trait Anxiety Inventory, STAI) and stress (Psychosocial Well-being Index, PWI) in both groups. Result(s): STAI (p=.018) and PWI (p=.006) between the experimental and control groups showed a statistically significant difference. But, cortisol, heart rate variability and serotonin were not significantly different between the two groups after the program Conclusion(s): These results show that forest/thermal combined therapy are effective for smokers" anxiety and stress. It is necessary to extend the duration of the program to determine its effect on cortisol, heart rate variability and serotonin.