Slow relaxation of randomly packed hard spheres

Lee, Jongjin,Lee, Changwon,Yu, Insuk,Jung, Youngkyun,Lee, Jysoo IOP Pub 2007 Journal of Physics, Condensed Matter Vol.19 No.35

<P>We discover that the apparent weight and the electrical resistance of randomly packed stainless steel balls exhibit unusually slow relaxation behavior. It is found experimentally that these relaxations are due to structural change of the packing. Simultaneous measurements of the apparent weight and the electrical resistance show correlated time dependence. We have also performed two-dimensional molecular dynamics simulations and studied a possible mechanism for the slow relaxation behavior observed in experiments.</P>

The Clinical Impact of 21-Gene Recurrence Score on Treatment Decisions for Patients with Hormone Receptor-Positive Early Breast Cancer in Korea

Lee, Moo Hyun,Han, Wonshik,Lee, Jeong Eon,Kim, Ku Sang,Park, Heeseung,Kim, Jongjin,Bae, Soo Youn,Shin, Hyun Joo,Lee, Jong Won,Lee, Eun Sook Korean Cancer Association 2015 Cancer Research and Treatment Vol.47 No.2

<P><B>Purpose</B></P><P>The 21-gene (Oncotype DX) recurrence score (RS) assay is useful in predicting the benefits of adjuvant chemotherapy for early breast cancer patients and is widely used in Western countries. However, to date, it has not gained much popularity in East Asia. We analyzed the results from five institutions’ experience from using the 21-gene assay and examined the impact of assay results on decision making of chemotherapy in Korean breast cancer patients and the associations between RS and clinicopathologic characteristics.</P><P><B>Materials and Methods</B></P><P>The 21-gene assay was performed on 212 patients with estrogen receptor-positive early breast cancer in five institutions. Each center made systemic treatment decisions both before and after the knowledge of assay results.</P><P><B>Results</B></P><P>Among the 212 patients, 132 (62.3%) had a low RS of < 18, 60 (28.3%) had an intermediate RS of 18-30, and 20 (9.4%) had a high RS of ≥ 31. Histologic grade, presence of micrometastases, Ki-67, and presence of lymphatic invasion were statistically associated with the RS results. Treatment decisions were changed in 115 of 212 patients (54.2%) in 109 of 212 (51.4%) from chemotherapy plus hormone therapy to hormone therapy, and in six of 212 (2.8%) from hormone therapy to chemotherapy plus hormone therapy.</P><P><B>Conclusion</B></P><P>The 21-gene breast cancer assay proved to have a significant impact on treatment decision- making. The test reduces chemotherapy use in more than 50% of Korean estrogen receptor-positive, early breast cancer patients.</P>

Monoclonal antibody K312-based depletion of pluripotent cells from differentiated stem cell progeny prevents teratoma formation

( Jongjin Park ),( Dong Gwang Lee ),( Na Geum Lee ),( Min-gi Kwon ),( Yeon Sung Son ),( Mi-young Son ),( Kwang-hee Bae ),( Jangwook Lee ),( Jong-gil Park ),( Nam-kyung Lee ),( Jeong-ki Min ) 생화학분자생물학회 2022 BMB Reports Vol.55 No.3

Human pluripotent stem cells (PSCs) have been utilized as a promising source in regenerative medicine. However, the risk of teratoma formation that comes with residual undifferentiated PSCs in differentiated cell populations is most concerning in the clinical use of PSC derivatives. Here, we report that a monoclonal antibody (mAb) targeting PSCs could distinguish undifferentiated PSCs, with potential teratoma-forming activity, from differentiated PSC progeny. A panel of hybridomas generated from mouse immunization with H9 human embryonic stem cells (hESCs) was screened for ESC-specific binding using flow cytometry. A novel mAb, K312, was selected considering its high stem cell-binding activity, and this mAb could bind to several human induced pluripotent stem cells and PSC lines. Cell-binding activity of K312 was markedly decreased as hESCs were differentiated into embryoid bodies or by retinoic acid treatment. In addition, a cell population negatively isolated from undifferentiated or differentiated H9 hESCs via K312 targeting showed a significantly reduced expression of pluripotency markers, including Oct4 and Nanog. Furthermore, K312-based depletion of pluripotent cells from differentiated PSC progeny completely prevented teratoma formation. Therefore, our findings suggest that K312 is utilizable in improving stem cell transplantation safety by specifically distinguishing residual undifferentiated PSCs. [BMB Reports 2022; 55(3): 142-147]

Graphene oxide induces apoptotic cell death in endothelial cells by activating autophagy via calcium-dependent phosphorylation of c-Jun N-terminal kinases

Lim, Mi-Hee,Jeung, In Cheul,Jeong, Jinyoung,Yoon, Sung-Jin,Lee, Sang-Hyun,Park, Jongjin,Kang, Yu-Seon,Lee, Hansu,Park, Young-Jun,Lee, Hee Gu,Lee, Seon-Jin,Han, Baek Soo,Song, Nam Woong,Lee, Sang Chul Elsevier 2016 Acta Biomaterialia: structure-property-function re Vol.46 No.-

<P><B>Abstract</B></P> <P>Despite the rapid expansion of the biomedical applications of graphene oxide (GO), safety issues related to GO, particularly with regard to its effects on vascular endothelial cells (ECs), have been poorly evaluated. To explore possible GO-mediated vasculature cytotoxicity and determine lateral GO size relevance, we constructed four types of GO: micrometer-sized GO (MGO; 1089.9±135.3nm), submicrometer-sized GO (SGO; 390.2±51.4nm), nanometer-sized GO (NGO; 65.5±16.3nm), and graphene quantum dots (GQDs). All types but GQD showed a significant decrease in cellular viability in a dose-dependent manner. Notably, SGO or NGO, but not MGO, potently induced apoptosis while causing no detectable necrosis. Subsequently, SGO or NGO markedly induced autophagy through a process dependent on the c-Jun N-terminal kinase (JNK)-mediated phosphorylation of B-cell lymphoma 2 (Bcl-2), leading to the dissociation of Beclin-1 from the Beclin-1–Bcl-2 complex. Autophagy suppression attenuated the SGO- or NGO-induced apoptotic cell death of ECs, suggesting that SGO- or NGO-induced cytotoxicity is associated with autophagy. Moreover, SGO or NGO significantly induced increased intracellular calcium ion (Ca<SUP>2+</SUP>) levels. Intracellular Ca<SUP>2+</SUP> chelation with BAPTA-AM significantly attenuated microtubule-associated protein 1A/1B-light chain 3-II accumulation and JNK phosphorylation, resulting in reduced autophagy. Furthermore, we found that SGO or NGO induced Ca<SUP>2+</SUP> release from the endoplasmic reticulum through the PLC β3/IP<SUB>3</SUB>/IP<SUB>3</SUB>R signaling axis. These results elucidate the mechanism underlying the size-dependent cytotoxicity of GOs in the vasculature and may facilitate the development of a safer biomedical application of GOs.</P> <P><B>Statement of Significance</B></P> <P>Graphene oxide (GO) have received considerable attention with respect to their utilization in biomedical applications. However, GO-related safety issues concerning human vasculature are very limited. In this manuscript, we report for the first time the differential size-related biological effects of GOs on endothelial cells (ECs). Notably, Subnanometer- and nanometersized GOs induce apoptotic death in ECs via autophagy activation. We propose a molecular mechanism for the GO-induced autophagic cell death through the PLCβ3/IP3/Ca<SUP>2+</SUP>/JNK signaling axis. Our findings could be provide a better understanding of the GO sizedependent cytotoxicity in vasculature and facilitate the future development of safer biomedical applications of GOs.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Rapid and facile synthesis of a (Zn_<i>x</i>Ag_<i>y</i>In_<i>z</i>)S₂ nanocrystal library <i>via</i> sono-combichem method and its characterization including single nanocrystal analysis

Lee, Seung Jae,Kim, Younggyu,Jung, Jongjin,Kim, Mi Ae,Kim, Namdoo,Lee, Seong Jin,Kim, Seong Keun,Kim, Yong-Rok,Park, Joung Kyu The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.24

<P>We have developed a facile and rapid synthesis of a highly fluorescent nanocrystal (NC) library, based on ultrasonic and combinatorial chemistry. Among a total of 66 tZAIS ((Zn<SUB><I>x</I></SUB>Ag<SUB><I>y</I></SUB>In<SUB><I>z</I></SUB>)S<SUB>2</SUB>) NCs, many NCs are highly fluorescent upon UV irradiation, and are categorized into blue, green, yellow, orange, and red by their distinct emission wavelength ranges. The tZAIS NCs not only have long fluorescence lifetimes, but also show comparable or even higher brightness than QDs without photoblinking in single NC analysis. Their unique photophysical properties together with less-toxic nature can permit the tZAIS system to be practically utilized in various bioimaging fields, especially single nanoparticle-based imaging and tracking.</P> <P>Graphic Abstract</P><P>The (Zn<SUB><I>x</I></SUB>Ag<SUB><I>y</I></SUB>In<SUB><I>z</I></SUB>)S<SUB>2</SUB> nanocrystal library based sono-combichem method can be utilized in bioimaging due to their unique photophysical properties such as brightness, non-blinking, long fluorescence lifetime, and less-toxic nature. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm31838e'> </P>

Diagnostic yield of stool culture and predictive factors for positive culture in patients with diarrheal illness

Lee, Jae Young,Cho, Sun Young,Hwang, Hannah Sun Hae,Ryu, Ja Young,Lee, Jongjin,Song, In Do,Kim, Beom Jin,Kim, Jeong Wook,Chang, Sae Kyung,Choi, Chang Hwan Williams & Wilkins Co 2017 Medicine Vol.96 No.30

<P><B>Abstract</B></P><P>We aimed to investigate the diagnostic yield of stool cultures and identify predictive factors for positive cultures in patients with diarrheal illness.</P><P>A total of 13,327 patients who underwent stool cultures due to diarrheal illness were reviewed. Stool cultures were performed for enteric pathogens, including Salmonella, Shigella, Vibrio, <I>Klebsiella oxytoca</I>, and <I>Yersinia</I>. The culture-positive group was compared with the culture-negative group who were randomly selected from culture negative patients.</P><P>A total of 196 patients (1.47%) were diagnosed with positive stool culture. In 196 culture positive patients, Salmonella spp. (75.0%) was detected most commonly, followed by Vibrio (19.4%). Univariate analyses showed fever (>37.8°C), vomiting, duration and frequency of diarrhea, and high C-reactive protein (CRP) were significantly associated with positive stool culture. Multivariate analysis showed fever (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.25–4.35; <I>P</I> = .008), ≥5/day of diarrhea (OR, 3.52; 95% CI, 1.93–6.44; <I>P</I> < .001) and >50 mg/L of CRP (OR, 2.27; 95% CI, 1.18–4.36; <I>P</I> = .014) were independent predictors for positive stool culture. OR in patients with all 3 factors was 6.55 (95% CI, 2.56–16.75; <I>P</I> < .001). Vomiting (OR, 0.32; 95% CI, 0.17–0.57; <I>P</I> < .001) was a negative predictive factor.</P><P>Diagnostic yield of stool culture in patients with diarrheal illness is very low. Fever, frequency of diarrhea, and high CRP are predictors for positive stool cultures. These findings may lead to more discerning and cost-effective utilization of stool culture by clinicians.</P>

Self-collimation-based photonic crystal Mach–Zehnder demultiplexer

Lee, Sun-Goo,Jung, Soo-Yong,Lee, Jongjin,Park, Jong-Moon,Kee, Chul-Sik IOP 2016 Journal of optics Vol.18 No.9

<P>A photonic crystal Mach–Zehnder demultiplexer (PC-MZDmux) with four output ports based on the self-collimation phenomenon in a two-dimensional (2D) PC is proposed and numerically studied using finite-difference time-domain simulations. The PC-MZDmux is composed of three Mach–Zehnder interferometers (MZIs) and each MZI consists of two 50:50 beam splitters and two perfect mirrors. Employed as the design parameters to achieve the demultiplexing functionality are the radius of phase control rods (PCRs) in the mirrors and the distance between the beam spitter and the mirror in the three MZIs. From spatial electric field distributions and transmission spectra, it is demonstrated that an incident self-collimated beam with four different frequencies can be demultiplexed to four output ports of the PC-MZDmux with proper design parameters. Our results indicate that this device design may constitute an efficient approach to light propagation manipulation and increase the application range of self-collimated beams.</P>

Coupled-cavity-based slow light metamaterials with antireflection structures

Lee, Sun-Goo,Kim, Seong-Han,Jung, Soo-Yong,Lee, Jongjin,Park, Jong-Moon,Kee, Chul-Sik American Institute of Physics 2016 APPLIED PHYSICS LETTERS Vol.109 No.22

GaN Growth on SiC (0001) Substrates by Metal-Organic Chemical Vapor Deposition

Lee, Kyungbae,So, Byeongchan,Lee, Kyungjae,Heo, Cheon,Ko, Kwangse,Jang, Jongjin,Nam, Okhyun American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.11

<P>In this study, the effects of the AlN buffer thickness and off-cut angles of 6H-SiC substrates on the crystallinity of GaN layers deposited via high-temperature metal organic chemical vapor deposition were investigated. The crystallinity of the GaN layers on the on-axis substrates was enhanced as the AlN buffer thickness increased. In contrast, the crystallinity of the GaN layers on the off-axis substrates was improved by applying relatively thinner AlN buffer layers. The strain relaxation of the GaN layers was closely related to the AlN buffer thickness and off-cut angles. Cathodoluminescence measurements revealed that the dark spot densities relative to defects were 1.9x10(8) and 8.9x10(7) cm(-2) for the on-and off-axis substrates, respectively. Cross-sectional transmission electron microscopy images showed that the screw and edge dislocation densities of the GaN layers deposited on off-axis substrates were reduced because of the bending of dislocations, which is due to macro-step bunching.</P>

Effect of Keratin-Based Biocomposite Hydrogels as a RhBMP-2 Carrier in Calvarial Bone Defects Mouse Model

Jongjin Lee,Jinsu Kang,Jaewon Seol,Nam-soo Kim,허수영 한국임상수의학회 2022 한국임상수의학회지 Vol.39 No.6

Recently, in human medicine and veterinary medicine, interest in syn- thetic bone graft is increasing. Among them, bone morphogenic protein (BMP) is currently being actively researched and applied to clinical trials. However, BMP has the disadvantage of being expensive and easily absorbed into surrounding tissues. Therefore, BMP requires the use of small amounts and rhBMP (recombi- nant human bone morphogenetic protein)-2 carriers that can be released slowly. Hydrogel has the property of swelling a large amount of water inside when it is aqueous solution, and when it is, it consists of more than 90 percent water. Using these properties, hydrogels are often used as rhBMP-2 carrier. The scaffold used in this study is a hydrogel made from which keratin is extracted using hu- man hair and based on it. In this study, we wanted to see the effect of bone for- mation in the calvarial defect model by using keratin-based hydrogel made with human hair as a scaffold. The experiment was conducted by dividing 3 groups a total of 12 mice. Calvarial bone defect is set to all 4 mm diameters. Bone for- mation was evaluated by using gross evaluation, micro-computed tomography (micro-CT), immunohistochemistry. Groups using keratin-based hydrogel were significantly observed compared to Group 1s, and the most bone formations were found when rhBMP-2 and hydrogel were used. This represents the supe- riority of the functions of the rhBMP-2 carrier by a new material, keratin-based hydrogel. Through gross evaluation, micro-CT, and immunohistochemistry, we can confirm that keratin-based hydrogel is a useful rhBMP-2 carrier.