377 research outputs found
Dasom Kwon, piano, Wednesday, February 26, 2014
No full textIn partial fulfillment of the requirements for the degree of
Master of Musi
Hyemin Kim, violin, Tuesday, April 1, 2014
No full textIn partial fulfillment of the requirements for the degree of
Artist Diplom
Electrochemical Evolution of Ru-based Polyoxometalates into Si,W-codoped RuOx for Acidic Overall Water Splitting
No full textDespite intensive studies over decades, the development of electrocatalysts for acidic water splitting still relies on platinum group metals (PGM), especially Pt and Ir, which are scarce, expensive, and poorly sustainable. Because such problems can be alleviated, Ru-based bifunctional catalysts such as rutile RuO2 have recently emerged. However, RuO2 has a relatively low activity for hydrogen evolution reactions (HER) and low stability for oxygen evolution reactions (OER) under acidic conditions. In this study, we report the synthesis of a RuOx-based bifunctional catalyst (RuSiW) for acidic water splitting via the electrochemical evolution from Ru-based polyoxometalates at cathodic potentials. RuSiW consists of the nanocrystalline RuO2 core and Si,W-codoped RuOx shell. RuSiW exhibits outstanding HER and OER activity comparable to Pt/C and RuO2, respectively, with high stability. Computational analysis suggests that the codoping of RuOx with W and Si synergistically improves the HER activity of otherwise poor RuO2 by shifting the d-band center and optimizing atomic configurations beneficial for proper hydrogen adsorption. This study provides insights into the design and synthesis of unprecedented bifunctional electrocatalysts using catalytically inactive and less explored elements, such as Si and W
Formyl-methionine as an N-degron of a eukaryotic N-end rule pathway
No full textIn bacteria, nascent proteins bear the pretranslationally generated N-terminal (Nt) formyl-methionine (fMet) residue. Nt-fMet of bacterial proteins is a degradation signal, termed fMet/N-degron. By contrast, proteins synthesized by cytosolic ribosomes of eukaryotes were presumed to bear unformylated Nt-Met. Here we found that the yeast formyltransferase Fmt1, although imported into mitochondria, could also produce Nt-formylated proteins in the cytosol. Nt-formylated proteins were strongly up-regulated in stationary phase or upon starvation for specific amino acids. This up-regulation strictly required the Gcn2 kinase, which phosphorylates Fmt1 and mediates its retention in the cytosol. We also found that the Nt-fMet residues of Nt-formylated proteins act as fMet/N-degrons and identified the Psh1 ubiquitin ligase as the recognition component of the eukaryotic fMet/N-end rule pathway, which destroys Nt-formylated proteins.111Nsciescopu
비항체 단백질 골격을 이용한 사이토카인에 대한 검출 민감도 및 혈액 내 순환시간 증대
No full text학위논문(박사) - 한국과학기술원 : 생명과학과, 2021.8,[ⅸ, 87 p. :]Cytokines are key signaling molecules to mediate and regulate inflammatory responses in the immune system. They mediate the activity and proliferation of immune cells for effective immune responses. Based on these attributes, cytokines have been used as immunological biomarkers for diagnosis of tumor or chronic inflammatory autoimmune diseases. Therefore, precise and sensitive detection of cytokine is essential for early diagnosis to increase therapeutic efficacy. In addition, cytokines have therapeutic potential in cancer treatment because it has an ability to directly stimulate the proliferation and cytotoxic functions of NK cells and T cells. However, due to the extremely short half-life of cytokine in the blood, there are many limitations in real medical application. Thus, there have been many efforts to extend the half-life of cytokines by modifying with Fc region of antibody, polyethylene glycol (PEG) and all that sort of things.
In chapter 1, we present a sensitive immunoassay platform using DNA-tethered gold nanoparticles and repebody to detect tumor necrosis factor alpha (TNF-α) which is a representative inflammatory cytokine. The DNA-tethered AuNPs were reacted with two different zinc finger proteins which had been genetically fused to a TNF-α-specific protein binder and alkaline phosphatase, respectively. Functionalized gold nanoparticles were used as a signal generator for colorimetric immunoassay of TNF-α. The functionalized gold nanoparticle-based immunoassay system has been confirmed high reproducibility and sensitivity, having 160-fold enhanced detection limit compared with conventional system.
In chapter 2, we developed human interleukin 15 (hIL15) which can efficiently activate NK cells and T cells with a dramatically increased half-life by fusing the human serum albumin specific protein binders (rHSA) to maximize treatment efficacy. To maintain the biological function of each part, rHSA and hIL15 were fused into one considering structure-based protein engineering. We provide evidence supporting the improved pharmacokinetics of hIL15 through in vivo test, and the result showed a nearly 40-fold longer half-life. Furthermore, anti-tumor activity of rHSA-hIL15 were also proved in two types of melanoma xenograft mouse model.
In this study, we successfully develop the immunoassay platform for the sensitive cytokine detection and the cancer immunotherapeutics for the effective extension of half-life, based on the use of non-antibody protein scaffold. Our results suggest that the cytokines which have both potentials, biomarkers or therapeutics, could be utilized to particular purposes by utilizing protein engineering for the development of detection system or therapeutics.한국과학기술원 :생명과학과
Abstract 482: miRNAs involved in LY6K and estrogen receptor-α contribute to tamoxifen susceptibility in breast cancer
No full textAbstract
Estrogen receptor-alpha is a clinically important therapeutic target for breast cancer. However, tumors that lose ERα are less responsive to anti-estrogens such as tamoxifen. MicroRNAs are small RNAs that regulate expression of their target gene and dysregulations of miRNA has been identified in many diseases including human cancer. However, only a few miRNAs associated with tamoxifen resistance has been reported. In this study, we found that lymphocyte antigen 6 complex, which is a member of the Ly-6/μPAR superfamily and related to breast cancer progression and metastasis, is inversely correlated with ERα expression. We, for the first time, found miRNAs involved in the regulatory molecular mechanism between ERα and LY6K and related to tamoxifen susceptibility in breast cancer. miR-192-5p, induced by LY6K, downregulates ERα directly and induced tamoxifen resistance in ERα-positive breast cancer cells. In addition, re-expression of ERα in ERα-negative breast cancer cells increased miR-500a-3p expression and directly inhibits LY6K expression. Ectopic expression of miR-500a-3p sensitized ERα-negative cells to tamoxifen by increasing apoptosis. Finally, we observed an inverse correlation between LY6K and ERα in primary breast cancer samples. We found that patients with recurrence showed high expression of miR-192-5p after tamoxifen treatments. In addition, expression of miR-500a-3p was significantly correlated to survival outcome. As miRNAs involved in the regulatory mechanism between LY6K and ERα can affect tamoxifen resistance, downregulating miR-192-5p or re-expressing miR-500a-3p could be a potential therapeutic approach for treating tamoxifen resistant patients.
Citation Format: Yesol Kim, Dasom Son, Kyung Hyun Yoo, Jong Hoon Park. miRNAs involved in LY6K and estrogen receptor-α contribute to tamoxifen susceptibility in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 482. doi:10.1158/1538-7445.AM2017-482</jats:p
Thermal Ablation and High-Resolution Imaging Using a Back-to-Back (BTB) Dual-Mode Ultrasonic Transducer: In Vivo Results
No full textWe present a back-to-back (BTB) structured, dual-mode ultrasonic device that incorporates a single-element 5.3 MHz transducer for high-intensity focused ultrasound (HIFU) treatment and a single-element 20.0 MHz transducer for high-resolution ultrasound imaging. Ultrasound image-guided surgical systems have been developed for lesion monitoring to ensure that ultrasonic treatment is correctly administered at the right locations. In this study, we developed a dual-element transducer composed of two elements that share the same housing but work independently with a BTB structure, enabling a mode change between therapy and imaging via 180-degree mechanical rotation. The optic fibers were embedded in the HIFU focal region of ex vivo chicken breasts and the temperature change was measured. Images were obtained in vivo mice before and after treatment and compared to identify the treated region. We successfully acquired B-mode and C-scan images that display the hyperechoic region indicating coagulation necrosis in the HIFU-treated volume up to a depth of 10 mm. The compact BTB dual-mode ultrasonic transducer may be used for subcutaneous thermal ablation and monitoring, minimally invasive surgery, and other clinical applications, all with ultrasound only.11Ysciescopu
Factors associated with partitioning behavior of persistent organic pollutants in a feto-maternal system: A multiple linear regression approach
No full textPrenatal exposure to persistent organic pollutants (POPs) has been a matter of particular concern because such exposure can severely affect the health of the fetus. The mechanistic understanding of the partitioning behavior of POPs in the feto-maternal system and the associated factors, however, have rarely been studied. Here, we employed a new approach based on multiple linear regression (MLR) analysis to predict the feto-maternal ratio (FM-ratio) of POPs and to assess the factors associated with feto-maternal partitioning behavior. Two preliminary exploratory MLR models were built using physiological conditions of the participants, and molecular descriptors were calculated with a computational model. The FM-ratio was calculated from the concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs) in 20 pairs of maternal and cord blood. The models showed that the lipids and cholesterols in the maternal and cord blood and the placenta significantly influence the partitioning of POPs. The body mass index (BMI) change during pregnancy was also related to the FM-ratio. The physicochemical properties associated with lipophilicity and molecular size were also related to the FM-ratio. Even though the results should be interpreted with caution, the preliminary MLR models illustrate that feto-maternal partitioning is governed by transplacental transporting mechanisms, toxicokinetics, and the molecular physicochemical properties of POPs. Overall, the new approach used in this study can improve our understanding of the partitioning behavior in the feto-maternal system. (C) 2020 Published by Elsevier Ltd
염료 컬러 레지스트용 이온성 바인더 폴리머의 합성에 관한 연구
No full text학위논문(석사) - 한국과학기술원 : 화학과, 2015.8
,[iv, 39P :]다양한 염료들이 액정 디스플레이 패널의 컬러필터 응용에 연구되어 오고있다. 그 이유는 염료는 안료에 비해 입자크기가 작아 잘 분산될 수 있기 때문이다. 그러므로 염료를 사용하게되면 빛 산란을 줄여줄 뿐만아니라 명암비와 휘도를 증가시켜 줄 수 있다. 그러나 염료들은 용액내에서는 잘 녹아 있더라도 가열과정시 응집되는 문제가 발생한다. 이러한 응집물들은 오히려 빛의 산란을 증가시키고 분광학적 특성인 휘도와 명암비를 감소시키게 된다. 따라서 다이의 응집을 막기위해 다이와 상호작용 가능한 그룹을 도입하여 바인더 폴리머를 디자인하게 되었다. 폴리머 합성은 methacrylic acid, butyl methacrylate, 2-ethylhexyl methacrylate and the 2-(methacryloyloxy)ethyl]trimethylammonium chloride를 이용해 라디칼 중합하였다. 또한 추가적으로 폴리머내에 이중결합을 도입함으로써 반응성 모노머와 가교결합을 형성하게 해주었으며 이로 인해 배향막 공정중 NMP 용액내로 다이가 새어나오는 문제를 억제할 수 있었다. 합성된 바인더 폴리머들은 기존의 바인더 폴리머에 비해 다이의 응집을 억제시킬 뿐만 아니라 더 향상된 분광학적 특성을 얻을것으로 기대된다.한국과학기술원 :화학과
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