Activating Injury-Responsive Genes with Hypoxia Enhances Axon Regeneration through Neuronal HIF-1α

Cho, Y.,Shin, J.,Ewan, E.,Oh, Y.,Pita-Thomas, W.,Cavalli, V. Cell Press 2015 Neuron Vol.88 No.4

Injured peripheral neurons successfully activate a proregenerative transcriptional program to enable axon regeneration and functional recovery. How transcriptional regulators coordinate the expression of such program remains unclear. Here we show that hypoxia-inducible factor 1α (HIF-1α) controls multiple injury-induced genes in sensory neurons and contribute to the preconditioning lesion effect. Knockdown of HIF-1α in vitro or conditional knock out in vivo impairs sensory axon regeneration. The HIF-1α target gene Vascular Endothelial Growth Factor A (VEGFA) is expressed in injured neurons and contributes to stimulate axon regeneration. Induction of HIF-1α using hypoxia enhances axon regeneration in vitro and in vivo in sensory neurons. Hypoxia also stimulates motor neuron regeneration and accelerates neuromuscular junction re-innervation. This study demonstrates that HIF-1α represents a critical transcriptional regulator in regenerating neurons and suggests hypoxia as a tool to stimulate axon regeneration.

Hexanal-induced changes in miRNA-mRNA interactions in A549 human alveolar epithelial cells

Cho, Y.,Lim, J. h.,Jeong, S. C.,Song, M. K.,Ryu, J. C. Springer Science + Business Media 2015 Toxicology and Environmental Health Sciences Vol.7 No.2

Spectral evidence for multi-pathway contribution to the upconversion pathway in NaYF4:Yb3+,Er3+ phosphors

Cho, Y.,Song, S.,Lim, S.,Kim, J.,Park, C.,Kim, H. Royal Society of Chemistry 2017 Physical chemistry chemical physics Vol.19 No.10

<P>Although upconversion phosphors have been widely used in nanomedicine, laser engineering, bioimaging, and solar cell technology, the upconversion luminescence mechanism of the phosphors has been fiercely debated. A comprehensive understanding of upconversion photophysics has been significantly impeded because the number of photons incorporated in the process in different competitive pathways could not be resolved. Few convincing results to estimate the contribution of each of the two-, three-, and four-photon channels of near-infrared (NIR) energy have been reported in yielding upconverted visible luminescence. In this study, we present the energy upconversion process occurring in NaYF4: Yb3+, Er3+ phosphors as a function of excitation frequency and power density. We investigated the upconversion mechanism of lanthanide phosphors by comparing UV/VIS one-photon excitation spectra and NIR multi-photon spectra. A detailed analysis of minor transitions in one-photon spectra and luminescence decay enables us to assign electronic origins of individual bands in multi-photon upconversion luminescence and provides characteristic transitions representing the corresponding upconversion channel. Furthermore, we estimated the quantitative contribution of multiple channels with respect to irradiation power and excitation energy.</P>

Direct Gingival Fibroblast/Osteoblast Transdifferentiation via Epigenetics

Cho, Y.,Kim, B.,Bae, H.,Kim, W.,Baek, J.,Woo, K.,Lee, G.,Seol, Y.,Lee, Y.,Ku, Y. Journal of Dental Research, Inc 2017 Journal of dental research Vol.96 No.5

<P>Alveolar bone resorption caused by trauma or periodontal diseases has represented a challenge for both dental clinicians and researchers. In this study, we evaluate the osteogenic potential of human gingival fibroblasts (HGFs) through a direct transdifferentiation from HGFs to functional osteoblasts via epigenetic modification and osteogenic signaling with bone morphogenetic protein 2 (BMP2) in vitro and in vivo. HGF treatment with 5-aza-2'-deoxycytidine (5-aza-dC) induced demethylation in the hypermethylated CpG islands of the osteogenic lineage marker genes RUNX2 and ALP, and subsequent BMP2 treatment successfully drove the fibroblasts to the osteoblasts' lineage. Cell morphological changes viewed under microscopy and alkaline phosphatase (ALP) and alizarin red S (ARS) staining confirmed the osteoblastic change mediated by epigenetic modification as did real-time polymerase chain reaction (PCR), methylation-specific PCR (MSP), and chromatin immunoprecipitation (ChIP) assay, which demonstrated the altered methylation patterns in the RUNX2 and ALP promoter regions and their effect on gene expression. Furthermore, micro-computed tomography (CT) analysis of in vivo mouse cell transplantation experiments showed high-density signal in the epigenetically modified HGF group; in addition, a significant amount of bone formation was observed in the transplanted material using hematoxylin and eosin (H&E) staining as well. Collectively, our results indicate that epigenetic modification permits the direct programming of HGFs into functional osteoblasts, suggesting that this approach might open a novel therapeutic avenue in alveolar bone regeneration.</P>

The distribution, characteristics and utilization of Korean native Actinidia Genus

Cho, Y.,Cho, H.,Park, M. Korean Association of Organic Agriculture 2011 韓國有機農業學會誌 Vol.19 No.S

A. arguta is found nationwide whether the altitude is low or high if good drainage is achieved with plenty of water. The distribution of A. polygama seems to be more limited to higher altitude than A. arguta so it can be found in deep valley of highland even in Mt. Halla. A. kolomikta seems rather limited to colder area than A. arguta to Mt. Jiri to the south. Meanwhile, A. rufa is very confined to southern islands including Jeollanamdo and Jeju islands. Some institutes still continue to utilize Korean native Actinidia plants commercially since early 1980's. More collaborative efforts are needed for further development of these plants nationwide.

A Study of Predicting Method of Residual Stress Using Artificial Neural Network in $CO_2$Arc welding

Cho, Y.,Rhee, S.,Kim, J.H. The Korean Welding and Joining Society 2001 International journal of Korean welding society Vol.1 No.2

A prediction method for determining the welding residual stress by artificial neural network is proposed. A three-dimensional transient thermo-mechanical analysis has been performed for the $CO_2$ arc welding using the finite element method. The first part of numerical analysis performs a three-dimensional transient heat transfer analysis, and the second part then uses the results of the first part and performs a three-dimensional transient thermo-elastic-plastic analysis to compute transient and residual stresses in the weld. Data from the finite element method are used to train a back propagation neural network to predict the residual stress. Architecturally, the fully interconnected network consists of an input layer for the voltage and current, a hidden layer to accommodate the failure mechanism mapping, and an output layer for the residual stress. The trained network is then applied to the prediction of residual stress in the four specimens. It is concluded that the accuracy of the neural network predicting method is fully comparable with the accuracy achieved by the traditional predicting method.

Silicone rubber with mussel-inspired adhesive coatings for enhancing antifouling property and blood compatibility

Cho, Y.,Seo, S. Y.,Park, B. J.,Joung, Y. K.,Han, D. K. Springer Science + Business Media 2017 Macromolecular Research Vol.25 No.8

Pore size effect on the formation of polymer nanotubular structures within nanoporous templates

Cho, Y.,Lee, C.,Hong, J. Elsevier 2014 Colloids and surfaces. A, Physicochemical and engi Vol.443 No.-

Nanotubular structures have recently received much attention due to their potential applications in biosensors, drug delivery systems, electronic devices, and many others. The layer-by-layer (LbL) deposition technique on 3-dimensional templates has been one of the most popular methods for the formation of nanotubular structures. Any size, shape, and composition template can be utilized and the desired amount of various materials can be readily incorporated within the thin film geometry with nanoscale control. Therefore, the morphological features of those materials can easily be tuned by varying the structural properties of templates. However, LbL deposition within a confined geometry actually shows somewhat different results due to the geometrical restriction, which is still not fully understood so far. In the present study, in order to investigate such a template effect on the LbL process, we utilized a cylindrical nanoporous anodic aluminum oxide (AAO) structure as a template for the LbL process, yielding polymer nanotube structures. By varying the pore size of the porous templates, we determined the LbL process within porous structures was strongly governed by the geometrical characteristics of the utilized templates.

Current practices and economic performances of organic kiwifruit production in comparison with conventional one in Korea

Cho, Y.,Cho, H.,Park, M.,Ma, K. Korean Association of Organic Agriculture 2011 韓國有機農業學會誌 Vol.19 No.S

Organic production practices varied among producers. Generally, organic producers were relying on imported input materials such as organic compost and liquid fertilizer even more than conventional producers. Very few organic farmers had composting facilities or sites for the own supply of compost in need. The productivity of organic kiwifruit orchard (92%) was not as low as that of conventional while the net income (243%) was more than double that of conventional. This was mainly attributed to high farm gate price of organic fruits, low paid labour use and electricity. As a consequence, organic kiwifruit production seems to become a feasible option in Korea. However, high dependence on imported farming material, fuel and labour for too frequent liquid fertilizer spray should be addressed to achieve long term sustainability of organic kiwifruit production.

Ruthenium bipyridyl complex-sensitized dechlorination of CCl₄ in aqueous micellar solutions under visible light

Cho, Y.,Park, Y.,Choi, W. Korean Society of Industrial and Engineering Chemi 2008 Journal of industrial and engineering chemistry Vol.14 No.3

The sensitized dechlorination of CCl<SUB>4</SUB> in water was successfully demonstrated in the presence of nonionic surfactants (Brij-35) and ruthenium bipyridyl complexes [Ru<SUP>II</SUP>(bpy)<SUB>3</SUB>] under visible light illumination (λ>420nm). The ruthenium complex plays the role of a visible light sensitizer for this reductive conversion process, which is excited by absorbing visible light and subsequently transfers an electron to CCl<SUB>4</SUB>. The photoinduced electron transfers from the excited sensitizer to CCl<SUB>4</SUB> take place only in the presence of the surfactant, which concentrates both reactants within a micelle. The ruthenium sensitizer should be oxidized after transferring an electron to CCl<SUB>4</SUB>, but immediately regenerated by abstracting an electron from surrounding surfactant molecules. As a result, the ruthenium sensitizer acts as a photocatalyst with producing chlorides far above the stoichiometric concentration of the added sensitizer. The dechlorination rate was significantly reduced in the presence of dissolved oxygen, because the excited sensitizer is quenched by O<SUB>2</SUB>. With increasing each concentration of the surfactant, sensitizer, or CCl<SUB>4</SUB>, the corresponding CCl<SUB>4</SUB> dechlorination rate progressively increased, to reach a saturation at the concentration of 4.0g/L (surfactant), 5μM (sensitizer), or 30mM (CCl<SUB>4</SUB>), respectively. The visible light activity was strongly dependent on the kind of surfactants as well.