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Search Results: 1 - 10 of 41000 matches for " Yun Jong Lee "
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The genome-scale metabolic network analysis of Zymomonas mobilis ZM4 explains physiological features and suggests ethanol and succinic acid production strategies
Kyung Lee, Jong Park, Tae Kim, Hongseok Yun, Sang Lee
Microbial Cell Factories , 2010, DOI: 10.1186/1475-2859-9-94
Abstract: The genome-scale metabolic model of Z. mobilis ZM4, ZmoMBEL601, was reconstructed based on its annotated genes, literature, physiological and biochemical databases. The metabolic model comprises 579 metabolites and 601 metabolic reactions (571 biochemical conversion and 30 transport reactions), built upon extensive search of existing knowledge. Physiological features of Z. mobilis were then examined using constraints-based flux analysis in detail as follows. First, the physiological changes of Z. mobilis as it shifts from anaerobic to aerobic environments (i.e. aerobic shift) were investigated. Then the intensities of flux-sum, which is the cluster of either all ingoing or outgoing fluxes through a metabolite, and the maximum in silico yields of ethanol for Z. mobilis and Escherichia coli were compared and analyzed. Furthermore, the substrate utilization range of Z. mobilis was expanded to include pentose sugar metabolism by introducing metabolic pathways to allow Z. mobilis to utilize pentose sugars. Finally, double gene knock-out simulations were performed to design a strategy for efficiently producing succinic acid as another example of application of the genome-scale metabolic model of Z. mobilis.The genome-scale metabolic model reconstructed in this study was able to successfully represent the metabolic characteristics of Z. mobilis under various conditions as validated by experiments and literature information. This reconstructed metabolic model will allow better understanding of Z. mobilis metabolism and consequently designing metabolic engineering strategies for various biotechnological applications.The impact of biotechnology on industry and society is dramatically gaining momentum, particularly in the field of agriculture-food, medicine and chemical production. For the chemical industry, which aims to producing value-added chemicals and fuels in a sustainable way, efforts have been put into strain improvement of microorganisms, utilizing many newly emergin
Macrophage PD-L1 strikes back: PD-1/PD-L1 interaction drives macrophages toward regulatory subsets  [PDF]
Yun-Jung Lee, Young-Hye Moon, Kyeong Eun Hyung, Jong-Sun Yoo, Mi Ji Lee, Ik Hee Lee, Byung Sung Go, Kwang Woo Hwang
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.48A3003
Abstract:

Activated macrophages have been simply de?ned as cells that secrete in?ammatory mediators and kill intracellular pathogens until few years ago. Recent studies have proposed a new classification system to separate activated macrophages based on their functional phenotypes: host defense, wound healing, and immune regulation. Regulatory macrophages can arise following innate or adaptive immune responses and hinder macrophage-mediated host defense and inflammatory functions by inhibiting the production of pro-inflammatory mediators. In this study, we investigated whether PD-1 and PD-L1 interaction between macrophages and T cells alters macrophage activities. Our data provide evidence for PD-1/PD-L1 engagement inducing a regulatory profile in macrophages. Regulatory macrophages derived from PD-L1 signaling lost their host defense activity, which consists of the production of pro-inflammatory cytokine IL-6 and the exhibition of increased IL-10, SPHK1 and LIGHT gene levels in early phases of LPS stimulation. This differentiation seems to occur through excessive activation of TLR4 downstream MAPK signaling pathways. Regulatory macrophages induced from PD-1/PD-L1 interaction decrease inflammatory mediators and produce anti-inflammatory cytokines, so this macrophage subset has been under considerable attention as a possible immune regulation mechanism. Understanding and modulating regulatory macrophages may lead to new approches to treat or prevent auto-immune diseases such as type I diabetes, rheumatic syndrome and hypersensitivity-related diseases, which are concerned with the overproduction of inflammatory cytokines in macroages.

Various Flash Memory Devices of Novel Design
Yun Jang-Gn,Lee Jong,Park Byung-Gook
IETE Technical Review , 2009,
Abstract: Various novel flash memory devices for both NOR and NAND types are reviewed. In NOR-type flash memory devices, 2-bit/cell devices and their technology trends are addressed. Furthermore, multi-site -charge-trapping schemes with more-than-2-bit/cell operation are also studied in the fin SONOS (silicon oxide-nitride oxide semiconductor) flash memory having independent double gates and the stacked vertical-channel NOR flash memory. In the NAND-type flash memory, devices having extended word-lines are investigated. As well as the short-channel effect, fluctuation and process limitation issues are considered for the highly scaled devices. Some future perspectives, including a stacked array, are discussed for high-density NAND flash memories.
On the Polarization of H-alpha Lines Scattered by Neutral Hydrogen in Active Galactic Nuclei
Hee-Won Lee,Jong-Hyeun Yun
Physics , 1998, DOI: 10.1046/j.1365-8711.1998.02028.x
Abstract: Raman scattering by atomic hydrogen converts the UV continuum around Ly$\beta$ into optical continuum around H$\alpha$, and the basic atomic physics has been discussed in several works on symbiotic stars. We propose that the same process may operate in active galactic nuclei (AGN) and calculate the linear polarization of the broad emission lines Raman-scattered by a high column neutral hydrogen compnent. The conversion efficiency of the Raman scattering process is discussed and the expected scattered flux is computed using the spectral energy distribution of an AGN given by a typical power law. The high column H {\sc i} component in AGN is suggested by many observations encompassing radio through UV and X-ray ranges. When the neutral hydrogen component with a column density $\sim 10^{22} cm^{-2}$ is present around the active nucleus, it is found that the scattered H$\alpha$ is characterized by a very broad width $\sim 20,000 km/s$ and that the strength of the polarized flux is comparable to that of the electron-scattered flux expected from a conventional unified model of narrow line AGN. The width of the scattered flux is mainly determined by the column density of the neutral scatterers where the total scattering optical depth becomes of order unity. The asymmetry in the Raman scattering cross section around Ly$\beta$ introduces red asymmetric polarized profiles around H$\alpha$. The effects of the blended Ly$\beta$ and O {\sc vi} 1034 doublet are also investigated. We briefly discuss the spectropolarimetric observations performed on the Seyfert galaxy IRAS 110548-1131 and the narrow line radio galaxy Cyg A.
Robotic versus Endoscopic Thyroidectomy for Thyroid Cancers: A Multi-Institutional Analysis of Early Postoperative Outcomes and Surgical Learning Curves
Jandee Lee,Jong Ho Yun,Un Jong Choi,Sang-Wook Kang,Jong Ju Jeong,Woong Youn Chung
Journal of Oncology , 2012, DOI: 10.1155/2012/734541
Abstract: Robotic thyroidectomy is an emerging technique with postoperative outcomes that are at least comparable to those of conventional endoscopic thyroidectomy, with some end-points appearing superior. Our multicenter series represents the largest comparison of robotic and endoscopic thyroidectomy to date, with results suggesting a comparable robot technology we used that could overcome some of the technical limitations associated with conventional endoscopic procedures, with reduced operation times and increased lymph node retrieval. Moreover, we found that the learning curve for robotic thyroidectomy was shorter than that for endoscopic thyroidectomy. 1. Introduction Endoscopic surgical techniques for thyroid cancer surgery can benefit patients by eliminating the anterior neck incision utilized in the traditional open approach. In addition to superior cosmetic results, endoscopic thyroidectomy can reduce postoperative pain and discomfort, shorten hospital stay, and enhance postoperative recovery [1–4]. Despite these advantages, however, endoscopic thyroidectomy has technical limitations, including the use of straight, rigid endoscopic instruments without articulation and a 2Dimensional (2D) view. The recent introduction of the da Vinci robot surgical system may be a major improvement in extracervical approaches for thyroid surgery and may be more ergonomic for surgeons than the endoscopic approach [5–7]. Among the advantages of the da Vinci robot are improved visualization via a 3D view, magnification, a tremor-filtering system, and instrument flexibility. To date, however, few studies have compared the postoperative outcomes in patients undergoing robotic and endoscopic thyroid surgery [8–11]. At present, endoscopic techniques are regarded as too time consuming and technically demanding to be adopted on a large-scale. The learning curve for endoscopic thyroidectomy performed by skilled endocrine surgeons has been estimated to be approximately 60 patients [12]. Use of a robot in thyroid surgery may shorten the learning curve, by providing a broader view of the surgical field and easier access to deep and narrow spaces through the use of multiarticulated instruments. We have previously reported the results of a multicenter study of learning curves for robotic thyroidectomy, based on a scientific analysis of a range of perioperative parameters [13]. However, there have been few comparisons of learning curves for robotic and endoscopic thyroidectomies. At present, the benefits of robotic thyroidectomy relative to endoscopic thyroidectomy, as determined by
What Questions do People Ask on a Human Papillomavirus Website? A Comparative Analysis of Public and Private Questions
Sung-Jong Lee, Hae-Jung Yun, Keun-Ho Lee, Chan-Joo Kim, Jong-Sup Park
International Journal of Medical Sciences , 2012,
Abstract: Objective: In 2004, we launched the question and answer (Q&A) section on a human papillomavirus (HPV) website (www.hpvkorea.org) that provides ample and regularly updated information about HPV. The purpose of this study is to collect data pertaining to questions posed on this website about HPV and its related diseases and analyze the type of questions and frequency before and after introduction of HPV vaccine in Korea. Using these results, we intend to determine the clinical and practical implications for doctors treating HPV and for HPV website providers. Method: Data were collected from March 2004 to July 2011. This study analyzed all the questions that were asked on the website during this period. The questions were categorized into 2 groups, according to whether they were asked publicly or privately. The 10 categories for classification were determined on the basis of the contents of the questions by 4 researchers with medical degrees (Ph.D.) related to HPV research. The frequency of the questions was separately determined for the public and private question formats. Also, we compared the type of questions and frequency before and after introduction of HPV vaccine in Korea and evaluated the changes in the 2 groups over the 2 periods studied. Results: Of the 3,062 subjects who visited the HPV website, 2,330 subjects asked public questions and 732 asked private questions. The most frequent question was “I have been infected with HPV, and I want to know about the treatment options for HPV infection and cervical dysplasia” (n = 1156, 37.8%), and the second most common question was “What are the transmission routes of HPV?” (n = 684, 22.3%). The third most common question was “How long does it take for HPV infection to spontaneously remit?” (n = 481, 15.7%). Of the 2,330 public questions, the most common question types pertained to the treatment of HPV and cervical dysplasia, HPV transmission, HPV remission, and risk of cervical cancer (in that order). Of the 732 private questions, the most frequent question types pertained to the HPV transmission, treatment of HPV and cervical dysplasia, genital warts, and HPV & pregnancy (in that order). The type and frequency of public and private questions showed statistical differences between the 2 groups (p < 0.001). Conclusion: Our results show that when people consult an internet site about HPV, they actually want to seek about “treatment of HPV and cervical dysplasia”, “HPV transmission”, “HPV remission”, “genital warts”, and “risk of cervical cancer” (in this order). Also, our results showed that “genital wart
Risk Factors of Neonatal Anemia in Placenta Previa
Dong Gyu Jang, Yun Sung Jo, Sung Jong Lee, Gui Se Ra Lee
International Journal of Medical Sciences , 2011,
Abstract: Objectives: Placenta previa is a major cause of neonatal anemia. The purpose of this study was to elucidate the risk factors of neonatal anemia in placenta previa. Methods: The study was conducted on 158 placenta previa patients at 3 hospitals in affiliation with the Catholic Medical Center, Seoul, Korea from May 1999 through December 2009. The subjects were divided in to 2 groups: 47 placenta previa patients with neonatal anemia, and 113 placenta previa patients without neonatal anemia. The subjects' characteristics were compared. Logistic regression was used to control for confounding factors. Results: Anterior placental location (OR 2.48; 95% CI: 1.20-5.11) was an independent risk factor of neonatal anemia after controlling for potential confounders. Conclusion: To manage neonatal anemia in placenta previa patients, obstetricians should do their best to detect placental location. Pediatricians should consider the high possibility of neonatal anemia in cases involving anterior placental location.
Filiform polyposis in the sigmoid colon: A case series
Chang Geun Lee, Yun Jeong Lim, Jong Sun Choi, Jin Ho Lee
World Journal of Gastroenterology , 2010,
Abstract: Filiform polyposis is a rare condition of uncertain pathogenesis that is usually found in association with Crohn’s disease, ulcerative colitis, intestinal tuberculosis or histiocytosis X. We report seven interesting cases of polyposis with various pathologic components, mainly located in the left side of the colon with no associated inflammatory bowel disease, intestinal tuberculosis or histiocytosis X. Multiple finger-like polypoid lesions with the appearance of stalactites were noted on the left side of the colon, especially in the sigmoid area, at the time of colonoscopy. The polyps had a variety of sizes and shapes and were shown to have various histopathologic components among the different patients. Although filiform polyposis localized in the sigmoid colon appears not to have high oncogenic potential, periodic follow-up seems to be needed.
Spin relaxation in mesoscopic superconducting Al wires
Yun-Sok Shin,Hu-Jong Lee,Hyun-Woo Lee
Physics , 2004, DOI: 10.1103/PhysRevB.71.144513
Abstract: We studied the diffusion and the relaxation of the polarized quasiparticle spins in superconductors. To that end, quasiparticles of polarized spins were injected through an interface of a mesoscopic superconducting Al wire in proximity contact with an overlaid ferromagnetic Co wire in the single-domain state. The superconductivity was observed to be suppressed near the spin-injecting interface, as evidenced by the occurrence of a finite voltage for a bias current below the onset of the superconducting transition. The spin diffusion length, estimated from finite voltages over a certain length of Al wire near the interface, was almost temperature independent in the temperature range sufficiently below the superconducting transition but grew as the transition temperature was approached. This temperature dependence suggests that the relaxation of the spin polarization in the superconducting state is governed by the condensation of quasiparticles to the paired state. The spin relaxation in the superconducting state turned out to be more effective than in the normal state.
Endogenous Timing in Contests with Group-Specific Public-Goods Prizes  [PDF]
Jong Hwa Lee
Theoretical Economics Letters (TEL) , 2017, DOI: 10.4236/tel.2017.76112
Abstract: I analyze the two-group contest with the group-specific public-goods prize when each player decides on the timing of their moves endogenously and individually. Unlike the previous papers, I show that free riders suffer a damage in the endogenous-timing framework because the decision on the endogenous timing adversely affects the behavior of free riders, by making them more egotistical.
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