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Search Results: 1 - 10 of 26606 matches for " Bo-Young Yoon "
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Membrane Fusion Proteins of Type I Secretion System and Tripartite Efflux Pumps Share a Binding Motif for TolC in Gram-Negative Bacteria
Minho Lee, So-Young Jun, Bo-Young Yoon, Saemee Song, Kangseok Lee, Nam-Chul Ha
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040460
Abstract: The Hly translocator complex of Escherichia coli catalyzes type I secretion of the toxin hemolysin A (HlyA). In this complex, HlyB is an inner membrane ABC (ATP Binding Cassette)-type transporter, TolC is an outer membrane channel protein, and HlyD is a periplasmic adaptor anchored in the inner membrane that bridges HlyB to TolC. This tripartite organization is reminiscent of that of drug efflux systems such as AcrA-AcrB-TolC and MacA-MacB-TolC of E. coli. We have previously shown the crucial role of conserved residues located at the hairpin tip region of AcrA and MacA adaptors during assembly of their cognate systems. In this study, we investigated the role of the putative tip region of HlyD using HlyD mutants with single amino acid substitutions at the conserved positions. In vivo and in vitro data show that all mutations abolished HlyD binding to TolC and resulted in the absence of HlyA secretion. Together, our results suggest that, similarly to AcrA and MacA, HlyD interacts with TolC in a tip-to-tip manner. A general model in which these conserved interactions induce opening of TolC during drug efflux and type I secretion is discussed.
Mg Alloy Foam Fabrication via Melt Foaming Method

Donghui YANG,Changhwan SEO,Bo-Young HUR,

材料科学技术学报 , 2008,
Abstract: For the first time AZ91 (MgAl9Zn1) and AM60 (MgAl6) Mg alloy foams with homogeneous pore structures were prepared successfully via melt foaming method using CaCO3 as blowing agent. It is revealed that the blowing gas to foam the melt is not CO2 but CO, which comes from liquid-solid reaction between Mg melt. The reaction temperature is more than 100℃ lower than CaCO3 decomposition, which makes Mg alloy melts foam into cellular structure much more easily in the temperature range from 690℃ to 750℃.
Effects of the fourth component and undercooling on morphology of primary Mg-Zn-Y icosahedral quasicrystal phase under normal casting conditions
Wang Zhifeng,Zhao Weimin,Bo-Young Hur
China Foundry , 2009,
Abstract: The paper presents some results of the investigation on effects of the fourth component (Ti, C, Sb or Cu) and undercooling on the morphology, size and forming process of primary Mg-Zn-Y icosahedral quasicrystal phase (I-phase) under normal casting conditions. The result shows that the addition of certain amount of fourth component can transform I-phase morphology from petal-like to spherical. However, I-phase will grow up to petal-like if superfl uous addition of the fourth component applied. It is also found that the solidifi ed morphology of I-phase depends on the stability of spherical I-phase during the subsequent growth, and critical radius of maintaining the spherical I-phase interface relatively stable. Further, mini-sized spherical I-phase can be produced with high content of the fourth component by undercooling. Such fi ndings are benefi cial for industrializing Mgbased quasicrystals.
A new analysis technique to measure the W Production Charge Asymmetry at the Tevatron
Bodek, Arie;Chung, Yeonsei;Halkiadakis, Eva;Han, Bo-Young;McFarland, Kevin
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevD.77.111301
Abstract: We propose an analysis technique to directly measure W production charge asymmetry from W leptonic decay events at the Tevatron and show the feasibility for new analysis method using Monte Carlo simulations.
siRNA targeting Livin decreases tumor in a xenograft model for colon cancer
Bo-Young Og,Ryung-Ah Lee,Kwang Ho Kim
World Journal of Gastroenterology , 2011, DOI: 10.3748/wjg.v17.i20.2563
Abstract: AIM: To evaluate the effect of silencing Livin gene expression with siRNA to apoptosis and proliferation in a colon cancer cell line. METHODS: To investigate the anticancer effect of silencing Livin gene expression, we established an siRNA transfected cell line using the HCT116 colon cancer cell line. After confirming the successful transfection, MTT assay, flow cytometry and annexin V staining were employed to evaluate the antiapoptotic effect. To confirm the in vivo effect of Livin-siRNA, different doses of Livin-siRNA were injected into xenografted tumors in BALB/c nude mice model. RESULTS: Livin expression was dramatically decreased after siRNA transfection, especially at 25 μmol/L of siRNA, but this suppression was not dose-dependent. The cell count at 18 h after transfection was significantly reduced as compared with controls (P < 0.01), but tended not to decrease proportionally depending on transfected dose or time. MTT assay revealed that silencing the Livin gene suppressed cellular proliferation at 18 h after transfection (P = 0.04); however, the inhibitory effect disappeared thereafter. Also, there was no significant difference in cellular proliferation depending on siRNA dose. The rate of apoptosis also increased with silencing of the Livin gene. In vivo, the tumor size significantly decreased after Livin-siRNA injection at 20 μmol/L concentration (P = 0.03). There were no significant body weight changes of mice after siRNA injection. Histologic examination revealed no significant toxic reaction in kidney, liver and brain of mice. CONCLUSION: siRNA-mediated downregulation of Livin expression can induce apoptosis in colon cancer in vitro and in vivo, which suggests the possibility of new cancer therapeutics using siRNA.
Multipass Active Contours for an Adaptive Contour Map
Jeong Heon Kim,Bo-Young Park,Farhan Akram,Byung-Woo Hong,Kwang Nam Choi
Sensors , 2013, DOI: 10.3390/s130303724
Abstract: Isocontour mapping is efficient for extracting meaningful information from a biomedical image in a topographic analysis. Isocontour extraction from real world medical images is difficult due to noise and other factors. As such, adaptive selection of contour generation parameters is needed. This paper proposes an algorithm for generating an adaptive contour map that is spatially adjusted. It is based on the modified active contour model, which imposes successive spatial constraints on the image domain. The adaptability of the proposed algorithm is governed by the energy term of the model. This work focuses on mammograms and the analysis of their intensity. Our algorithm employs the Mumford-Shah energy functional, which considers an image’s intensity distribution. In mammograms, the brighter regions generally contain significant information. Our approach exploits this characteristic to address the initialization and local optimum problems of the active contour model. Our algorithm starts from the darkest region; therefore, local optima encountered during the evolution of contours are populated in less important regions, and the important brighter regions are reserved for later stages. For an unrestricted initial contour, our algorithm adopts an existing technique without re-initialization. To assess its effectiveness and robustness, the proposed algorithm was tested on a set of mammograms.
Neutrophils Promote Mycobacterial Trehalose Dimycolate-Induced Lung Inflammation via the Mincle Pathway
Wook-Bin Lee,Ji-Seon Kang,Ji-Jing Yan,Myeong Sup Lee,Bo-Young Jeon,Sang-Nae Cho,Young-Joon Kim
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002614
Abstract: Trehalose 6,6′-dimycolate (TDM), a cord factor of Mycobacterium tuberculosis (Mtb), is an important regulator of immune responses during Mtb infections. Macrophages recognize TDM through the Mincle receptor and initiate TDM-induced inflammatory responses, leading to lung granuloma formation. Although various immune cells are recruited to lung granulomas, the roles of other immune cells, especially during the initial process of TDM-induced inflammation, are not clear. In this study, Mincle signaling on neutrophils played an important role in TDM-induced lung inflammation by promoting adhesion and innate immune responses. Neutrophils were recruited during the early stage of lung inflammation following TDM-induced granuloma formation. Mincle expression on neutrophils was required for infiltration of TDM-challenged sites in a granuloma model induced by TDM-coated-beads. TDM-induced Mincle signaling on neutrophils increased cell adherence by enhancing F-actin polymerization and CD11b/CD18 surface expression. The TDM-induced effects were dependent on Src, Syk, and MAPK/ERK kinases (MEK). Moreover, coactivation of the Mincle and TLR2 pathways by TDM and Pam3CSK4 treatment synergistically induced CD11b/CD18 surface expression, reactive oxygen species, and TNFα production by neutrophils. These synergistically-enhanced immune responses correlated with the degree of Mincle expression on neutrophil surfaces. The physiological relevance of the Mincle-mediated anti-TDM immune response was confirmed by defective immune responses in Mincle?/? mice upon aerosol infections with Mtb. Mincle-mutant mice had higher inflammation levels and mycobacterial loads than WT mice. Neutrophil depletion with anti-Ly6G antibody caused a reduction in IL-6 and monocyte chemotactic protein-1 expression upon TDM treatment, and reduced levels of immune cell recruitment during the initial stage of infection. These findings suggest a new role of Mincle signaling on neutrophils during anti-mycobacterial responses.
Fabrication of Near Net Shape Metallic Foam via Plaster Mould

Young-Hwan Song,Hwan-Goo Seon,Soo-Han Parka,Min-Jae Jeong,Bo-Young Hur,

材料科学技术学报 , 2008,
Abstract: Fabrication characteristics are unstable in direct foaming method. Therefore, most of near net-shape metallic foams are produced, and investigated by powder metallurgy. Direct foaming method, however, has many benefits (i.e. reduce the unit cost of goods and fabrication process etc.) to fabrication of metallic foams. In this article, the fabrication characteristic of near net-shape metallic foams by direct foaming method was evaluated. AI and Plaster was used for base material and mould material respectively. Ca and TiH2 were added to molten Al as thickening and blowing agent for stable condition of bubbles. Thickening time was about 10 min with a stirring speed of 600 r/min. Foaming time was 30-120 s for evaluation of the optimum foaming condition. Amount of agent was selected by pre-experimental data. Porosity of near net-shape goods was measured by Archimedes method. On the other hand, it seems that increasing poring time and thickening agent make the poor porosity
An EST resource for tilapia based on 17 normalized libraries and assembly of 116,899 sequence tags
Bo-Young Lee, Aimee E Howe, Matthew A Conte, Helena D'Cotta, Elodie Pepey, Jean-Francois Baroiller, Federica di Palma, Karen L Carleton, Thomas D Kocher
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-278
Abstract: The ESTs were assembled into 20,190 contigs and 36,028 singletons for a total of 56,218 unique sequences and a total assembled length of 35,168,415 bp. Over the whole project, a unique sequence was discovered for every 2.079 sequence reads. 17,722 (31.5%) of these unique sequences had significant BLAST hits (e-value < 10-10) to the UniProt database.Normalization of the cDNA pools with double-stranded nuclease allowed us to efficiently sequence a large collection of ESTs. These sequences are an important resource for studies of gene expression, comparative mapping and annotation of the forthcoming tilapia genome sequence.Tilapia is the common name for a group of 40-50 nominal species of cichlid fishes (Order Perciformes) native to Africa and the Middle East. Tilapias have been an important aquaculture species for thousands of years. Sometimes called the 'aquatic chicken', tilapia are sturdy and adaptable fish, and are now cultured in more than 100 countries in Asia and the Americas [1]. Tilapias are a cornerstone of future aquaculture production, and genetic improvement of this species is needed to increase growth rate and improve disease resistance. Cichlid fishes are also important models for research on vertebrate physiology, behavior, and evolutionary biology. Because of their close evolutionary relationship, genetic resources developed for tilapia are also useful for studying the extraordinary radiation of haplochromine cichlids in the lakes of East Africa [2].Genetic resources for tilapia are relatively well developed, and include a microsatellite-based genetic map [3] and a physical map based on BAC fingerprints [4]. In contrast, EST resources for these species are limited. Modest EST projects have been published for some haplochromine cichlids [5-7]. Although several labs have constructed cDNA libraries for tilapia, and a few thousand ESTs have been characterized [8-10], until now large-scale sequencing of ESTs has not been pursued in tilapia.The applications
Metabolic Alterations of the Zebrafish Brain after Acute Alcohol Treatment by 1H Nuclear Magnetic Resonance Spectroscopy
Dong-Cheol Woo,Goo-Young Kim,Hyun-Ju Kim,Eunjung Bang,Hyang-Shuk Rhim,Sang-Young Kim,Do-Wan Lee,Chi-Bong Choi,Youl-Hun Seoung,Bo-Young Choe
Journal of Spectroscopy , 2013, DOI: 10.1155/2013/971914
Abstract: The purpose of this study is to investigate the metabolic alterations associated with acute alcohol treatment in zebrafish by 1H nuclear magnetic resonance spectroscopy (NMRS). The brain metabolism of zebrafish was investigated after acute alcohol treatment (one-hour long exposure of adult fish to 0.00%, 0.25%, 0.50%, or 1.00% ethyl alcohol) with whole brain extraction. The results of this study showed that glutamate (Glu) was significantly decreased, scyllo-inositol (sIns) showed a small apparent increase only in the highest acute treatment dose group, and myoinositol (mIns) showed a significant decrease. [Glu]/[tCr] and [mIns]/[tCr] levels were significantly reduced regardless of the alcohol dose, and [sIns]/[tCr] was increased in the highest alcohol treatment dose group. The present NMR study revealed that specific metabolites, such as Glu and mIns, were substantially decreased in case of acute alcohol exposed zebrafish brain. 1. Introduction Alcohol (i.e., EtOH, ethyl alcohol, and ethanol) abuse and alcoholism are prevalent conditions that cause significant problems for both individual patients and society. Alcohol abuse and alcoholism involve neural processes distinct from other addictions [1]. Attempts to understand the common and unique aspects of alcohol addiction have spurred investigators to adopt new animal models and research methods that have not been widely used for the investigation of other addictions. Partially, alcohol in the brain reduces glutamate and it could be interpreted as a response to N-methyl-D-aspartate (NMDA) receptor blockade [2, 3]. However, the mechanisms associated with alcohol addiction have not been completely identified [1, 4–6], despite numerous reported studies on the topic during the past several decades. Animal models, including zebrafish, mice, rats, and monkeys, have been used to study alcohol addiction and the physiology of alcoholism [1]. Zebrafish have become a popular subject for embryology studies in genetic research, as well as neurobiology over the past three decades [7]. Attempts at in vivo MR imaging (MRI) and MR spectroscopy (MRS) of zebrafish have recently been reported [8, 9]. NMRS is a common modality for research of neurological diseases, such as Alzheimer and Parkinson disease, as well as epilepsy, depression, and schizophrenia in both animals and humans [10–14]. Previous human NMRS studies in alcoholics have shown brain metabolic changes, particularly in the hippocampus, frontal cortex, basal ganglia, and cerebellum [15–17]. The N-acetyl aspartate (NAA), choline (Cho), and glutamic acids were
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