Negative regulation of SEK1 signaling by serum- and glucocorticoid-inducible protein kinase 1

Kim, Myung Jin,Chae, Ji Soo,Kim, Kwang Je,Hwang, Sang Gil,Yoon, Kyoung Wan,Kim, Eun Kyung,Yun, Hee Jae,Cho, Jun-Ho,Kim, Jeehyun,Kim, Bong-Woo,Kim, Hyung-chul,Kang, Sang Sun,Lang, Florian,Cho, Ssang-Go Wiley (John WileySons) 2007 The EMBO journal Vol.26 No.13

<P>Serum- and glucocorticoid-inducible protein kinase 1 (SGK1) has been implicated in diverse cellular activities including the promotion of cell survival. The molecular mechanism of the role of SGK1 in protection against cellular stress has remained unclear, however. We have now shown that SGK1 inhibits the activation of SEK1 and thereby negatively regulates the JNK signaling pathway. SGK1 was found to physically associate with SEK1 in intact cells. Furthermore, activated SGK1 mediated the phosphorylation of SEK1 on serine 78, resulting in inhibition of the binding of SEK1 to JNK1, as well as to MEKK1. Replacement of serine 78 of SEK1 with alanine abolished SGK1-mediated SEK1 inhibition. Oxidative stress upregulated SGK1 expression, and depletion of SGK1 by RNA interference potentiated the activation of SEK1 induced by oxidative stress in Rat2 fibroblasts. Moreover, such SGK1 depletion prevented the dexamethasone-induced increase in SGK1 expression, as well as the inhibitory effects of dexamethasone on paclitaxel-induced SEK1-JNK signaling and apoptosis in MDA-MB-231 breast cancer cells. Together, our results suggest that SGK1 negatively regulates stress-activated signaling through inhibition of SEK1 function.</P>

Two-axis polydimethylsiloxane-based electromagnetic microelectromechanical system scanning mirror for optical coherence tomography

Kim, Sehui,Lee, Changho,Kim, Jin Young,Kim, Jeehyun,Lim, Geunbae,Kim, Chulhong SPIE - International Society for Optical Engineeri 2016 JOURNAL OF BIOMEDICAL OPTICS Vol.21 No.10

High-resolution, dual-depth spectral-domain optical coherence tomography with interlaced detection for whole-eye imaging

Kim, Hyung-Jin,Kim, Pil Un,Hyeon, Min Gyu,Choi, Youngwoon,Kim, Jeehyun,Kim, Beop-Min The Optical Society 2016 Applied Optics Vol.55 No.26

<P>Dual-depth spectral-domain optical coherence tomography (SD-OCT) enables high-resolution in vivo whole-eye imaging. Two orthogonally polarized beams from a source are focused simultaneously on two axial positions of the anterior segment and the retina. For the detector arm, a 1 x 2 ultrafast optical switch sequentially delivers two spectral interference signals to a single spectrometer, which extends the in-air axial depth range up to 9.44 mm. An off-pivot complex conjugate removal technique doubles the depth range for all anterior segment imaging. The graphics-processing-unit-based parallel signal processing algorithm supports fast two-and three-dimensional image displays. The obtained high-resolution anterior and retinal images are measured biometrically. The dual-depth SD-OCT system has an axial resolution of similar to 6.4 mu m in air, and the sensitivity is 91.79 dB at 150 mu m from the zero-delay line. (C) 2016 Optical Society of America</P>

Skin pore imaging using spectral‑domain optical coherence tomography: a case report

Hyunmo Kim,Dongwan Kang,Daewoon Seong,Sm Abu Saleah,Jannat Amrin Luna,Yoonseok Kim,Hayoung Kim,Sangyeob Han,Mansik Jeon,Jeehyun Kim 대한의용생체공학회 2023 Biomedical Engineering Letters (BMEL) Vol.13 No.4

Sebum is an important component of the skin that has attracted attention in many fields, including dermatology and cosmetics. Pore expansion due to sebum on the skin can lead to various problems. Therefore, it is necessary to analyze the morphologicalcharacteristics of sebum. In this study, we used optical coherence tomography (OCT) to evaluate facial sebum areas. Weobtained the OCT maximum amplitude projection (MAP) image and a cross-sectional image of skin pores in the facial area. Subsequently, we detected the sebum in skin pores using the detection algorithm of the ImageJ software to quantitativelydetermine the size of randomly selected pores in the proposed MAP images. Additionally, the pore size was analyzed byacquiring images before and after facial sebum extraction. According to our research, facial sebum can be morphologicallydescribed using the OCT system. Since OCT imaging enables specific analysis of skin parameters, including pores andsebum, skin analysis employing OCT could be an effective method for further research.

웹진에 있어서의사용자 경험요소의 적용

김지현(Jeehyun Kim),이정연(Jeehyun Kim) 한국기초조형학회 2004 기초조형학연구 Vol.5 No.1

Stimulated penetrating keratoplasty using real-time virtual intraoperative surgical optical coherence tomography.

Lee, Changho,Kim, Kyungun,Han, Seunghoon,Kim, Sehui,Lee, Jun Hoon,Kim, Hong Kyun,Kim, Chulhong,Jung, Woonggyu,Kim, Jeehyun SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS 2014 JOURNAL OF BIOMEDICAL OPTICS Vol.19 No.3

<P>An intraoperative surgical microscope is an essential tool in a neuro- or ophthalmological surgical environment. Yet, it has an inherent limitation to classify subsurface information because it only provides the surface images. To compensate for and assist in this problem, combining the surgical microscope with optical coherence tomography (OCT) has been adapted. We developed a real-time virtual intraoperative surgical OCT (VISOCT) system by adapting a spectral-domain OCT scanner with a commercial surgical microscope. Thanks to our custom-made beam splitting and image display subsystems, the OCT images and microscopic images are simultaneously visualized through an ocular lens or the eyepiece of the microscope. This improvement helps surgeons to focus on the operation without distraction to view OCT images on another separate display. Moreover, displaying the OCT live images on the eyepiece helps surgeon's depth perception during the surgeries. Finally, we successfully processed stimulated penetrating keratoplasty in live rabbits. We believe that these technical achievements are crucial to enhance the usability of the VISOCT system in a real surgical operating condition.</P>

SynechoNET: integrated protein-protein interaction database of a model cyanobacterium <i>Synechocystis </i> sp. PCC 6803

Kim, Woo-Yeon,Kang, Sungsoo,Kim, Byoung-Chul,Oh, Jeehyun,Cho, Seongwoong,Bhak, Jong,Choi, Jong-Soon BioMed Central 2008 BMC bioinformatics Vol.9 No.suppl1

<P><B>Background</B></P><P>Cyanobacteria are model organisms for studying photosynthesis, carbon and nitrogen assimilation, evolution of plant plastids, and adaptability to environmental stresses. Despite many studies on cyanobacteria, there is no web-based database of their regulatory and signaling protein-protein interaction networks to date.</P><P><B>Description</B></P><P>We report a database and website SynechoNET that provides predicted protein-protein interactions. SynechoNET shows cyanobacterial domain-domain interactions as well as their protein-level interactions using the model cyanobacterium, <I>Synechocystis </I>sp. PCC 6803. It predicts the protein-protein interactions using public interaction databases that contain mutually complementary and redundant data. Furthermore, SynechoNET provides information on transmembrane topology, signal peptide, and domain structure in order to support the analysis of regulatory membrane proteins. Such biological information can be queried and visualized in user-friendly web interfaces that include the interactive network viewer and search pages by keyword and functional category.</P><P><B>Conclusion</B></P><P>SynechoNET is an integrated protein-protein interaction database designed to analyze regulatory membrane proteins in cyanobacteria. It provides a platform for biologists to extend the genomic data of cyanobacteria by predicting interaction partners, membrane association, and membrane topology of <I>Synechocystis </I>proteins. SynechoNET is freely available at or directly at .</P>

Design of mid-plane passive active multijunction antenna for 5-GHz KSTAR LHCD system

Kim, Jeehyun,Wang, Sonjong,Hillairet, Julien,Wi, Hyunho,Seon, Sangwon,Han, Jongwon,Delpech, Lena Elsevier 2017 Fusion engineering and design Vol.123 No.-

<P><B>Abstract</B></P> <P>The major upgrade of KSTAR LHCD system to 4MW is planned in 2021. 4-MW RF power will be provided by 8×0.5MW klystrons. Highly oversized circular waveguide transmitting TE<SUB>01</SUB>° mode will be adopted for the low loss transmission line longer than 50m. The design of the 4-MW mid-plane Passive Active Multijunction launcher has been performed. Considering parallel refractive index N<SUB>||</SUB> for the efficient current drive and the maximum power density at the launcher mouth, the launcher is composed of 256 active waveguides whose dimension is 58mm x 7mm and 18mm of spatial period for N<SUB>||0</SUB> =2.5. Multijunction with E<SUB>max <</SUB> 3.5kV/cm and high power waveguide components have been designed using HFSS code. The antenna properties were evaluated using ALOHA. Prototype PAM launcher with 32 active waveguides is under development for 0.5-MW pulsed operation.</P>

Validation of 500-kW/1000-s operation of 5-GHz klystron for KSTAR LHCD system

Kim, Jeehyun,Seong, Taesik,Park, Seungil,Bae, Y.S.,Delpech, Lena,Namkung, Won,Cho, Moohyun Elsevier 2019 Fusion engineering and design Vol.139 No.-

<P><B>Abstract</B></P> <P>In this study, a klystron for the KSTAR lower hybrid current drive (LHCD) system was developed as a prototype for a 5 GHz, 500 kW CW operation that is aimed to meet the requirement of the ITER LHCD system as well. Before the 2012 KSTAR campaign, the prototype klystron was validated only for 350 kW CW operation. The weakest part of the klystron for 500 kW CW operation was the RF output window failure due to a thermal stress caused by the temperature gradient. The klystron was equipped with two RF windows, each of which should transmit 250 kW power. Prior to the full performance test of the klystron, the performance of the test RF windows that were identical to those mounted on the klystron was tested with half of the klystron’s full power. The temperature increase in the test RF windows was monitored using an IR camera. The temperature difference, ΔT<SUB>ce</SUB>, between the center and edge of the test window at 250-kW 1000-s transmitting power was predicted to be 23 °C, which is smaller than the safe ΔT<SUB>ce</SUB>, which is 50 °C according to the manufacturer. Based on the result of the test window measurement, 500-kW 1000-s operation of the klystron was conducted successfully. The klystron output power characteristics depending on the phase of load reflection VSWR 1.4:1 were investigated. The klystron generated stable power on a load VSWR of 1.4:1 at various phases. The output power at the worst phase was 380 kW. Details of the IR-imaging setup are discussed and the results obtained are presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Validation of 5-GHz 500-kW CW operation of the klystron which is relevant to the ITER LHCD system. </LI> <LI> The weakest part was the RF window damage due to a thermal stress by the temperature gradient. </LI> <LI> The accurate temperature of the test RF window was monitored using IR camera with a calibration. </LI> <LI> The klystron operation at 500 kW for 1000s was successfully. </LI> <LI> The klystron characteristics with reflective load. </LI> </UL> </P>

Magnetomotive laser speckle imaging.

Kim, Jeehyun,Oh, Junghwan,Choi, Bernard SPIE--the International Society for Optical Engine 2010 JOURNAL OF BIOMEDICAL OPTICS Vol.15 No.1

<P>Laser speckle imaging (LSI) involves analysis of reflectance images collected during coherent optical excitation of an object to compute wide-field maps of tissue blood flow. An intrinsic limitation of LSI for resolving microvascular architecture is that its signal depends on relative motion of interrogated red blood cells. Hence, with LSI, small-diameter arterioles, venules, and capillaries are difficult to resolve due to the slow flow speeds associated with such vasculature. Furthermore, LSI characterization of subsurface blood flow is subject to blurring due to scattering, further limiting the ability of LSI to resolve or quantify blood flow in small vessels. Here, we show that magnetic activation of superparamagnetic iron oxide (SPIO) nanoparticles modulate the speckle flow index (SFI) values estimated from speckle contrast analysis of collected images. With application of an ac magnetic field to a solution of stagnant SPIO particles, an apparent increase in SFI is induced. Furthermore, with application of a focused dc magnetic field, a focal decrease in SFI values is induced. Magnetomotive LSI may enable wide-field mapping of suspicious tissue regions, enabling subsequent high-resolution optical interrogation of these regions. Similarly, subsequent photoactivation of intravascular SPIO nanoparticles could then be performed to induce selective photothermal destruction of unwanted vasculature.</P>