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Search Results: 1 - 10 of 9114 matches for " Myoung Hee Park "
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Gate-Tunable Spin Transport and Giant Electroresistance in Ferromagnetic Graphene Vertical Heterostructures
Nojoon Myoung,Hee Chul Park,Seung Joo Lee
Physics , 2015,
Abstract: We investigate spin transport through ferromagnetic graphene vertical heterostructures where a sandwiched tunneling layer is either a normal or ferroelectric insulator. We show that the spin-polarization of the tunneling current is electronically controlled via gate voltages. We also demonstrate that the tunneling current of Dirac fermions can be prohibited when the spin configuration of ferromagnetic graphene sheets is opposite. The giant electroresistance can thus be developed by using the proposed heterostructure in this study. The effects of temperature on the spin transport and the giant electroresistance ratio are also investigated. Our findings discover the prospect of manipulating the spin transport properties in vertical heterostructures through an electric fields via gate and bias electrodes.
Topical Application of Cudrania tricuspidata Stem Extract Inhibits Atopic Dermatitis-Like Skin Lesions in an NC/Nga Mouse Model: An Experimental Animal Study  [PDF]
Yoo-Sin Park, Shin-Hee Kim, Sang-Yeon Kim, Gae-Myoung Koh, Ju-Hwan Suh, Ju-Seop Kang
Pharmacology & Pharmacy (PP) , 2016, DOI: 10.4236/pp.2016.78044
Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by elevated immunoglobulin E (IgE), mast cell infiltration and skin lesions including pruritus, erythema and eczema. Cudrania tricuspidata extracts have been clinically administered for a long time in the East Asia including Korean and China as a home-remedy to diminish the inflammation of gastritis and hepatitis. To examine whether it works on AD or not, an AD-like animal model was experimented in this study. AD was induced by applying Dermatophagoides farinae (D. farinae) extract to the backs of 9-week old NC/Nga mice for 21 days. Following this, an ethanol extract of C. tricuspidata stems (EECT) was applied topically for 14 days to the sensitized skin, while distilled water was used as a control (EECT0 mice). Anti-AD effects of EECT were evaluated using scores for AD-like skin lesions, serum IgE levels and mast cell counts in the skin dermal layers to assess inflammation. Topically applied ethanol extract of Cudrania tricuspidata stems (EECT 7.5, 25 and 75 mg/mL) markedly reduced AD-like skin lesions after 4 days (by 30.1%, 31.4% and 38.5%, respectively) and also after 14 days (by 63.6%, 66.1% and 49.6%, respectively), while distilled water improved AD by 17.8% and 38.7%, respectively (p < 0.05). Serum IgE production was reduced in the EECT7.5, EECT25 and EECT75 groups after 4 days (by 57.6%, 65.9% and 59.3%, respectively) and after 14 days of the treatment (by 82.0%, 79.6% and 75.3%, respectively), while distilled water decreased it by 38.8% and 62.3% (p = 0.0001 and p = 0.0001, respectively). Mast cell counts increased after sensitization by D. farinae extract (p =
Platinum Assisted Vapor–Liquid–Solid Growth of Er–Si Nanowires and Their Optical Properties
Kim Myoung-Ha,Kim Il-Soo,Park Yong-Hee,Park Tae-Eon
Nanoscale Research Letters , 2009,
Abstract: We report the optical activation of erbium coated silicon nanowires (Er–SiNWs) grown with the assist of platinum (Pt) and gold (Au), respectively. The NWs were grown on Si substrates by using a chemical vapor transport process using SiCl4 and ErCl4 as precursors. Pt as well as Au worked successfully as vapor–liquid–solid (VLS) catalysts for growing SiNWs with diameters of ~100 nm and length of several micrometers, respectively. The SiNWs have core–shell structures where the Er-crystalline layer is sandwiched between silica layers. Photoluminescence spectra analyses showed the optical activity of SiNWs from both Pt and Au. A stronger Er3+ luminescence of 1,534 nm was observed from the SiNWs with Pt at room- and low-temperature (25 K) using the 488- and/or 477-nm line of an Ar laser that may be due to the uniform incorporation of more Er ions into NWs with the exclusion of the formation of catalyst-induced deep levels in the band-gap. Pt would be used as a VLS catalyst for high performance optically active Er–SiNWs.
Surface Wave Echo in a Semi-Bounded Plasma  [PDF]
Hee J. Lee, Myoung-Jae Lee
Journal of Modern Physics (JMP) , 2016, DOI: 10.4236/jmp.2016.712127
Abstract: Plasma echo theory is revisited to apply it to a semi-bounded plasma. Spatial echoes associated with plasma surface wave propagating in a semi-bounded plasma are investigated by calculating the second order electric field produced by external charges and satisfying the boundary conditions at the interface. The boundary conditions are two-fold: the specular reflection condition and the electric boundary condition. The echo spots are determined in terms of the perpendicular coordinate to the interface and the parallel coordinate along which the wave propagates. This improves the earlier works in which only the perpendicular coordinate is determined. In contrast with the echo in an infinite medium, echoes in a bounded plasma can occur at various spots. The diversity of echo occurrence spots is due to the discontinuity of the electric field at the interface that satisfies the specular reflection boundary condition. Physically, the diversity appears to be owing to the reflections of the waves from the interface.
Drosophila selenophosphate synthetase 1 regulates vitamin B6 metabolism: prediction and confirmation
Kwang Lee, Myoung Shim, Jin Kim, Hee Jung, Eunji Lee, Bradley A Carlson, Xue-Ming Xu, Jin Park, Dolph L Hatfield, Taesung Park, Byeong Lee
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-426
Abstract: Differentially expressed genes in Drosophila SL2 cells were identified using two-way analysis of variance methods and clustered according to their temporal expression pattern. Gene ontology analysis was performed against differentially expressed genes and gene ontology terms related to vitamin B6 biosynthesis were found to be significantly affected at the early stage at which megamitochondria were not formed (day 3) after SPS1 knockdown. Interestingly, genes related to defense and amino acid metabolism were affected at a later stage (day 5) following knockdown. Levels of pyridoxal phosphate, an active form of vitamin B6, were decreased by SPS1 knockdown. Treatment of SL2 cells with an inhibitor of pyridoxal phosphate synthesis resulted in both a similar pattern of expression as that found by SPS1 knockdown and the formation of megamitochondria, the major phenotypic change observed by SPS1 knockdown.These results indicate that SPS1 regulates vitamin B6 synthesis, which in turn impacts various cellular systems such as amino acid metabolism, defense and other important metabolic activities.Selenium has been reported to provide many health benefits in animals, including humans, when obtained from the diet in adequate amounts. For example, selenium has been known to play roles in cancer prevention, aging retardation, immune augmentation, prevention of heart diseases, muscle development and development [[1-4] and references therein]. Many of the health benefits of selenium are mediated by selenoproteins, which contain selenocysteine (Sec) as a selenium containing amino acid [3].Selenophosphate synthetase (SPS) synthesizes selenophosphate (SeP), the active selenium donor in Sec biosynthesis, using selenide and ATP as substrates [5]. SeP serves as a selenium donor during Sec biosynthesis [6]. Sec is contained in all selenoproteins [7]. SPS was first isolated from Escherichia coli as one of the enzymes involved in selenoprotein synthesis and was designated SelD [8]. Only one
Genetic Predisposition of Donors Affects the Allograft Outcome in Kidney Transplantation; Polymorphisms of Stromal-Derived Factor-1 and CXC Receptor 4
Jung Pyo Lee,Jong Bin Bae,Seung Hee Yang,Ran-hui Cha,Eun Young Seong,Yang Jin Park,Jongwon Ha,Myoung Hee Park,Jin Ho Paik,Yon Su Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016710
Abstract: Genetic interaction between donor and recipient may dictate the impending responses after transplantation. In this study, we evaluated the role of the genetic predispositions of stromal-derived factor-1 (SDF1) [rs1801157 (G>A)] and CXC receptor 4 (CXCR4) [rs2228014 (C>T)] on renal allograft outcomes. A total of 335 pairs of recipients and donors were enrolled. Biopsy-proven acute rejection (BPAR) and long-term graft survival were traced. Despite similar allele frequencies between donors and recipients, minor allele of SDF1 rs1801157 (GA+AA) from donor, not from recipients, has a protective effect on the development of BPAR compared to wild type donor (GG) (P = 0.005). Adjustment for multiple covariates did not affect this result (odds ratio 0.39, 95% C.I 0.20–0.76, P = 0.006). CXCR4 rs2228014 polymorphisms from donor or recipient did not affect the incidence of acute rejection. SDF1 was differentially expressed in renal tubular epithelium with acute rejection according to genetic variations of donor rs1801157 showing higher expressions in the grafts from GG donors. Contrary to the development of BPAR, the presence of minor allele rs1801157 A, especially homozygocity, predisposed poor graft survival (P = 0.001). This association was significant after adjusting for several risk factors (hazard ratio 3.01; 95% C.I = 1.19–7.60; P = 0.020). The allelic variation of recipients, however, was not associated with graft loss. A donor-derived genetic polymorphism of SDF1 has influenced the graft outcome. Thus, the genetic predisposition of donor should be carefully considered in transplantation.
Associations between the HLA-A polymorphism and the clinical manifestations of Behcet's disease
Eun Ha Kang, Jeong Yeon Kim, Fujio Takeuchi, Joon Wan Kim, Kichul Shin, Eun Young Lee, Yun Jong Lee, Eun Bong Lee, Myoung Hee Park, Yeong Wook Song
Arthritis Research & Therapy , 2011, DOI: 10.1186/ar3292
Abstract: Genotyping for the HLA-A locus was performed using the polymerase chain reaction-Luminex typing method in 223 BD patients and 1,398 healthy controls.The phenotypic frequencies of HLA-A*02:07 (odds ratio (OR) = 2.03, P = 0.002), A*26:01 (OR = 1.85, P = 0.008), and A*30:04 (OR = 2.51, P = 0.006) tended to be higher in BD patients than in normal controls, but the frequency of A*33:03 (OR = 0.59, P = 0.003) tended to be lower in BD patients. A meta-analysis adopting our and the Japanese data confirmed the associations of HLA-A*02:07, A*26:01, and A*33:03 with BD. Furthermore, the frequencies of the HLA-A*02:07, A*26:01, and A*30:04 were significantly higher in patients with skin lesions (OR = 2.37, P < 0.0005, Pc < 0.012) and arthritis (OR = 2.32, P = 0.002, Pc = 0.048), with uveitis (OR = 3.01, P < 0.0005, Pc < 0.012), and with vascular lesions (OR = 9.80, P < 0.0005, Pc < 0.012) and a positive pathergy test (OR = 4.10, P = 0.002, Pc = 0.048), respectively, than in controls. In HLA-B*51 non-carriers, these associations were also significant, being much stronger between HLA-A*26:01 and uveitis (OR = 4.19, P < 0.0005, Pc < 0.012) and between HLA-A*30:04 and vascular lesions (OR = 13.97, P < 0.00005, Pc < 0.0012). In addition, HLA-A*30:04 was associated with genital ulcers in HLA-B*51 non-carriers (OR = 3.89, P = 0.002, Pc = 0.048).HLA-A*02:07, A*26:01, and A*30:04 were associated with increased risk for BD, while HLA-A*33:03 with decreased risk. HLA-A*02:07, A*26:01, and A*30:04 were associated with skin lesions and arthritis, with uveitis, and with vascular lesions, genital ulcers, and a positive pathergy test, respectively.Behcet's disease (BD) is a chronic relapsing inflammatory disease characterized by oro-genital ulcers, cutaneous inflammation, and uveitis. In addition to its typical muco-cutaneous and ocular manifestations, BD targets the musculoskeletal, vascular, nervous, and gastrointestinal systems [1]. Although the etiology of BD remains unclear, strong famili
Molecular cloning and expression analysis of peptidase genes in the fish-pathogenic scuticociliate Miamiensis avidus
Jung Soo Seo, Eun Ji Jeon, Sung Hee Jung, Myoung Ae Park, Jin Woo Kim, Ki Hong Kim, Sung Ho Woo, Eun Hye Lee
BMC Veterinary Research , 2013, DOI: 10.1186/1746-6148-9-10
Abstract: The 17 genes encoding peptidases, including seven cathepsin-like cysteine peptidases, four serine carboxypeptidases, a eukaryotic aspartyl protease family protein, an ATP-dependent metalloprotease FtsH family protein, three leishmanolysin family proteins and a peptidase family M49 protein were identified from a Miamiensis avidus cDNA library by BLAST X search. Expression of genes encoding two cysteine peptidases, three leishmanolysin-like peptidases and a peptidase family M49 protein was up-regulated in the cell-fed ciliates compared to the starved ciliates. Especially, one cysteine peptidase (MaPro 4) and one leishmanolysin-like peptidase (MaPro 14) were transcribed more than 100-folds in the cell-fed ciliates.The genetic information and transcriptional characteristics of the peptidases in the present results would be helpful to elucidate the role of peptidases in the invasion of scuticociliates into their hosts.
Homeobox Transcription Factors Are Required for Conidiation and Appressorium Development in the Rice Blast Fungus Magnaporthe oryzae
Seryun Kim,Sook-Young Park,Kyoung Su Kim,Hee-Sool Rho,Myoung-Hwan Chi,Jaehyuk Choi,Jongsun Park,Sunghyung Kong,Jaejin Park,Jaeduk Goh,Yong-Hwan Lee
PLOS Genetics , 2009, DOI: 10.1371/journal.pgen.1000757
Abstract: The appropriate development of conidia and appressoria is critical in the disease cycle of many fungal pathogens, including Magnaporthe oryzae. A total of eight genes (MoHOX1 to MoHOX8) encoding putative homeobox transcription factors (TFs) were identified from the M. oryzae genome. Knockout mutants for each MoHOX gene were obtained via homology-dependent gene replacement. Two mutants, ΔMohox3 and ΔMohox5, exhibited no difference to wild-type in growth, conidiation, conidium size, conidial germination, appressorium formation, and pathogenicity. However, the ΔMohox1 showed a dramatic reduction in hyphal growth and increase in melanin pigmentation, compared to those in wild-type. ΔMohox4 and ΔMohox6 showed significantly reduced conidium size and hyphal growth, respectively. ΔMohox8 formed normal appressoria, but failed in pathogenicity, probably due to defects in the development of penetration peg and invasive growth. It is most notable that asexual reproduction was completely abolished in ΔMohox2, in which no conidia formed. ΔMohox2 was still pathogenic through hypha-driven appressoria in a manner similar to that of the wild-type. However, ΔMohox7 was unable to form appressoria either on conidial germ tubes, or at hyphal tips, being non-pathogenic. These factors indicate that M. oryzae is able to cause foliar disease via hyphal appressorium-mediated penetration, and MoHOX7 is mutually required to drive appressorium formation from hyphae and germ tubes. Transcriptional analyses suggest that the functioning of M. oryzae homeobox TFs is mediated through the regulation of gene expression and is affected by cAMP and Ca2+ signaling and/or MAPK pathways. The divergent roles of this gene set may help reveal how the genome and regulatory pathways evolved within the rice blast pathogen and close relatives.
Parasitic Nematode-Induced CD4+Foxp3+T Cells Can Ameliorate Allergic Airway Inflammation
Shin Ae Kang,Mi-Kyung Park,Min Kyoung Cho,Sang Kyun Park,Min Seong Jang,Bo-Gie Yang,Myoung Ho Jang,Dong-Hee Kim,Hak Sun Yu
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0003410
Abstract: Background The recruitment of CD4+CD25+Foxp3+T (Treg) cells is one of the most important mechanisms by which parasites down-regulate the immune system. Methodology/Principal Findings We compared the effects of Treg cells from Trichinella spiralis-infected mice and uninfected mice on experimental allergic airway inflammation in order to understand the functions of parasite-induced Treg cells. After four weeks of T. spiralis infection, we isolated Foxp3-GFP-expressing cells from transgenic mice using a cell sorter. We injected CD4+Foxp3+ cells from T. spiralis-infected [Inf(+)Foxp3+] or uninfected [Inf(-)Foxp3+] mice into the tail veins of C57BL/6 mice before the induction of inflammation or during inflammation. Inflammation was induced by ovalbumin (OVA)-alum sensitization and OVA challenge. The concentrations of the Th2-related cytokines IL-4, IL-5, and IL-13 in the bronchial alveolar lavage fluid and the levels of OVA-specific IgE and IgG1 in the serum were lower in mice that received intravenous application of Inf(+)Foxp3+ cells [IV(inf):+(+) group] than in control mice. Some features of allergic airway inflammation were ameliorated by the intravenous application of Inf(-)Foxp3+ cells [IV(inf):+(-) group], but the effects were less distinct than those observed in the IV(inf):+(+) group. We found that Inf(+)Foxp3+ cells migrated to inflammation sites in the lung and expressed higher levels of Treg-cell homing receptors (CCR5 and CCR9) and activation markers (Klrg1, Capg, GARP, Gzmb, OX40) than did Inf(-)Foxp3+ cells. Conclusion/Significance T. spiralis infection promotes the proliferation and functional activation of Treg cells. Parasite-induced Treg cells migrate to the inflammation site and suppress immune responses more effectively than non-parasite-induced Treg cells. The adoptive transfer of Inf(+)Foxp3+ cells is an effective method for the treatment and prevention of allergic airway diseases in mice and is a promising therapeutic approach for the treatment of allergic airway diseases.
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