COPOLYMER-MEDIATED FABRICATION OF VERSATILE ELECTRO-ACTIVE AND INFLAMMATION ATTENUATING SUBSTRATES FOR BIOLOGICAL INTERROGATION

EDWARD K. CHOW,BENJAMIN CHU,GENHONG CHENG,YU-CHONG TAI,ERIK PIERSTORFF,DEAN HO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2007 NANO Vol.2 No.6

Serving as platforms for both cellular interrogation as well as biomembrane mimicry, biotic–abiotic functionalized materials, such as block copolymeric membranes, offer the opportunity for tailored biology, where specific embedded functionalities can be rapidly engineered, on demand, without the need for genetic processing. These versatile materials enable rapid, thin film deposition of a plethora of biologically-relevant materials at the air–water interface given their amphiphilic properties, meaning that they possess alternating hydrophilic and hydrophobic components. This property confers to these materials the ability to be transferred to a wide range of substrates and materials, further enhancing their interfacial versatility. In addition, their biologically-inert, and tunable, thickness-dependent insulating properties serve as ideal bio-active substrates while maintaining the functionality of the integrated molecule (e.g., protein, effector molecule, etc.). Here, we report the application of a polyethyleneoxide–polymethylmethacrylate (PEO–PMMA) diblock and polymethyloxazoline–polydimethylsiloxane–polymethyloxazoline (PMOXA–PDMS–PMOXA) triblock copolymers as molecular anchors for tethering a broad spectrum of materials. These include carbon nanotubes for the fabrication of bioelectrodes to measure cytochrome c-mediated oxidation-reduction, as well as the anti-inflammatory molecule, dexamethasone, for the suppression of lipopolysaccharide (LPS)-induced inflammation in murine macrophages. As such, this work demonstrates the versatility, and broad applicability and impact of this platform approach towards the fabrication of multifunctional arrays of biologically-active surfaces for experimentation ranging from bio-electroactivity to studies of cellular immunity.

Effect of degumming conditions on the fluorescence intensity of fluorescent silk cocoons: A combined experimental and molecular dynamics study

Chan Yeong Yu,Ezekiel Edward Nettey-Oppong,Elijah Effah,Su Min Han,김성완,최승호 한국잠사학회 2022 International Journal of Industrial Entomology Vol.45 No.2

Silk is a unique natural biopolymer with outstanding biocompatibility, high mechanical strength, and superior optical transparency. Due to its excellent properties, silk has been widely reported as an ideal biomaterial for several biomedical applications. Recently, fluorescent silk protein, a variant of native silk, has been reported as a biophotonic material with the potential for bioimaging and biosensing. Despite the realization of fluorescent silk, the traditional degumming process of fluorescence silk is crude and often results in fluorescence loss. The loss of fluorescent properties is attributed to the sensitivity of silk fibroin to temperature and solvent concentration during degumming. However, there is no comprehensive information on the influence of these processing parameters on fluorescence evolution and decay during fluorescent silk processing. Therefore, we conducted a spectroscopic study on fluorescence decay as a function of temperature, concentration, and duration for fluorescent silk cocoon degumming. Sodium carbonate solution was tested for degumming the fluorescent silk cocoons with different concentrations and temperatures; also, sodium carbonate solution is combined with Alcalase enzyme and triton x-100 to find optimal degumming conditions. Additionally, we conducted a molecular dynamics study to investigate the fundamental effect of temperature on the stability of the fluorescent protein. We observed degumming temperature as the prime source of fluorescent intensity reduction. From the MD study, fluorescence degradation originated from the thermal agitation of fluorescent protein Cα atoms and fluctuations of amino acid residues located in the chromophore region. Overall, degumming fluorescent silk with sodium carbonate and Alcalase enzyme solution at 25 °C preserved fluorescence.

기계적으로 결합된 CNT/Cu 복합재료

피알라고 애드워드(Edward Joshua Pialago),정희여(Heeyeo Jung),유다영(Dayoung Yu),배성만(Seongman Bae),박찬우(Chan-Woo Park) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

In the present study, the mechanical alloying of carbon nanotubes (CNTs) and copper powder by ball milling is being investigated. Results show that the physical characteristics such as the dispersion of CNTs and the presence or absence of the agglomeration of particles are depended on the milling time and CNT content of the powder mixture. Depending on the end application of the CNT-Cu powder composite, the desired composite can be fabricated by controlling the milling parameters such as mixture composition, milling time as well as temperature.

Comment on “The Clinical Features and Pathophysiology of Acute Radiation Dermatitis in Patients Receiving Tomotherapy”

Slav Yartsev,Edward Yu 대한피부과학회 2011 Annals of Dermatology Vol.23 No.-

Letter to the Editor : Comment on "The Clinical Features and Pathophysiology of Acute Radiation Dermatitis in Patients Receiving Tomotherapy"

( Slav Yartsev ),( Edward Yu ) 대한피부과학회 2011 Annals of Dermatology Vol.23 No.1S

Activation of Antioxidant-Response Element (ARE), Mitogen- Activated Protein Kinases (MAPKs) and Caspases by Major Green Tea Polyphenol Components during Cell Survival and Death

Chen, Chi,Yu, Rong,Owuor, Edward D.,Kong, A.NTony The Pharmaceutical Society of Korea 2000 Archives of Pharmacal Research Vol.23 No.6

Green tea polyphenols (GTP) have been demonstrated to suppress tumorigenesis in several chemical-induced animal carcinogenesis models, and predicted as promising chemopreventive agents in human. Recent studies of GTP extracts showed the involvement of mitogen-activated protein kinases (MAPKs) in the regulation of Phase II enzymes gene expression and induction of apoptosis. In the current work we compared the biological actions of five green tea catechins: (1) induction of ARE reporter gene, (2) activation of MAP kinases, (3) cytotoxicity in human hepatoma HepG2-C8 cells, and (4) caspase activation in human cervical squamous carcinoma HeLa cells. For the induction of phase IIgene assay, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) potently induced antioxidant response element (ARE)-mediated luciferase activity, with induction observed at 25 $\mu\textrm{m}$with EGCG. The induction of ARE reporter gene appears to be structurally related to the 3-gallate group. Comparing the activation of MAPK by the five polyphenols, only EGCG showed potent activation of all three MAPKs (ERK, JNK and p38) in a dose- and time-dependent manner, whereas EGC activated ERK and p38. In the concentration range of 25 $\mu\textrm{m}$ to 1 mM, EGCG and ECG strongly suppressed HepG2-ARE-C8 cell-growth. To elucidate the mechanisms of green tea polyphenol-induced apoptosis, we measured the activation of an important cell death protein, caspase-3 induced by EGCG, and found that caspase-3 was activated in a dose- and time-dependent manner. Interestingly, the activation of caspase-3 was a relatively late event (peaked at 16 h), whereas activation of MAPKs was much earlier (peaked at 2 h). It is possible, that at low concentrations of EGCG, activation of MAPK leads to ARE-mediated gene expression including phase II detoxifying enzymes. Whereas at higher concentrations of EGCG, sustained activation of MAPKs such as JNK leads to apoptosis. These mechanisms are currently under investigation in our laboratory. As the most abundant catechin in GTP extract, we found that EGCG potently induced ARE-mediated gene expression, activated MAP kinase pathway, stimulated caspase-3 activity, and induced apoptosis. These mechanisms together with others, may contribute to the overall chemopreventive function of EGCG itself as well as the GTP.

Risk of second cancer among young prostate cancer survivors

Hong Zhang,Andrew Yu,Andrea Baran,Edward Messing 대한방사선종양학회 2021 Radiation Oncology Journal Vol.39 No.2

Purpose: About 40% of men diagnosed with prostate cancer (Pca) are ≤65 years of age. This study evaluates the risk of second cancer among young Pca patients treated with surgery or radiation. Materials and Methods: This is a retrospective review of 150,915 men aged ≤65 years at Pca diagnosis treated with surgery or radiation registered in the Surveillance, Epidemiology, and End Results (SEER) database between 1973 and 2014. Incidence rates of second rectum/rectosigmoid junction (RJ), bladder, and lung cancer in each treatment group were reported with adjustment for potential confounders. Cumulative incidence functions were used to summarize the risk of second cancer after completing initial treatment. Results: Men treated with external beam radiation (BEAM), brachytherapy (SEED), or combined radiation all exhibited a statistically significant increased incidence of second bladder cancer compared to men treated with surgery (adjusted incidence rate ratio [IRR]: 2.09, 1.91, and 2.04, respectively). Incidence of rectum/RJ cancer was also significantly increased in men receiving BEAM and combined radiation (adjusted IRR: 1.58 and 1.98, respectively). There were also significant differences in the cumulative incidence of second bladder cancer after receiving any form of radiation compared to surgery. Conclusion: Pca survivors ≤65 years of age at Pca diagnosis had an increased risk of second bladder and rectum/RJ cancer after BEAM and combined radiation treatment after adjusting for confounding factors. Second bladder cancer incidence after either form of radiation treatment was increased even at 5 years after a Pca diagnosis.

Risk of Diabetic Retinopathy between Sodium-Glucose Cotransporter-2 Inhibitors and Glucagon-Like Peptide-1 Receptor Agonists

Tzu-Yi Lin,Eugene Yu-Chuan Kang,Shih-Chieh Shao,Edward Chia-Cheng Lai,Sunir J. Garg,Kuan-Jen Chen,Je-Ho Kang,Wei-Chi Wu,Chi-Chun Lai,Yih-Shiou Hwang 대한당뇨병학회 2023 Diabetes and Metabolism Journal Vol.47 No.3

Background: To compare risk of diabetic retinopathy (DR) between patients taking sodium-glucose cotransporter-2 inhibitors (SGLT2is) and those taking glucagon-like peptide-1 receptor agonists (GLP1-RAs) in routine care.Methods: This retrospective cohort study emulating a target trial included patient data from the multi-institutional Chang Gung Research Database in Taiwan. Totally, 33,021 patients with type 2 diabetes mellitus using SGLT2is and GLP1-RAs between 2016 and 2019 were identified. 3,249 patients were excluded due to missing demographics, age <40 years, prior use of any study drug, a diagnosis of retinal disorders, a history of receiving vitreoretinal procedure, no baseline glycosylated hemoglobin, or no follow-up data. Baseline characteristics were balanced using inverse probability of treatment weighting with propensity scores. DR diagnoses and vitreoretinal interventions served as the primary outcomes. Occurrence of proliferative DR and DR receiving vitreoretinal interventions were regarded as vision-threatening DR.Results: There were 21,491 SGLT2i and 1,887 GLP1-RA users included for the analysis. Patients receiving SGLT2is and GLP-1 RAs exhibited comparable rate of any DR (subdistribution hazard ratio [SHR], 0.90; 95% confidence interval [CI], 0.79 to 1.03), whereas the rate of proliferative DR (SHR, 0.53; 95% CI, 0.42 to 0.68) was significantly lower in the SGLT2i group. Also, SGLT2i users showed significantly reduced risk of composite surgical outcome (SHR, 0.58; 95% CI, 0.48 to 0.70).Conclusion: Compared to those taking GLP1-RAs, patients receiving SGLT2is had a lower risk of proliferative DR and vitreoretinal interventions, although the rate of any DR was comparable between the SGLT2i and GLP1-RA groups. Thus, SGLT2is may be associated with a lower risk of vision-threatening DR but not DR development.

Mixture copulas with discrete margins and their application to imbalanced data

Liu Yujian,Xie Dejun,Edwards David A.,Yu Siyi 한국통계학회 2023 Journal of the Korean Statistical Society Vol.52 No.4

This article introduces the approach of using Bayesian sampling to estimate the mixture copula with discrete margins, we further apply our models to solve the class imbalanced problems in data science by oversampling. The methodology makes it possible to learn and sample from the data set with the discrete and continuous features exists simultaneously. On the other hand, the discreetness of factors in a data set are not naturally considered for the classic SMOTE algorithm and classic random oversampling is simply performed by generating the already existing points, which do not give any new information to the classifiers and is easy to overfit. Copula methods enable us to generate new points with the correlation structure memorized by learning from the training set. Hence, the overfitting problems are reduced. Experiments with synthetic and real data are done in the article following the introduction of the methodology. The outcomes shows the validity of the approach when compared with the benchmark methods.

Quality assessment of high performance concrete using digitized image elements

Sheng-Szu Peng,Her-Yung Wang,Yu-Te Chou,Edward H. Wang 사단법인 한국계산역학회 2012 Computers and Concrete, An International Journal Vol.10 No.4

The quality of high performance concrete largely depends on water cement ratio, porosity,material composition and mix methods. The uniformity of color, texture and compressive strengths are quality indicators commonly used to assess the overall characteristics of concrete mixes. The homogeneity and share of coarse aggregates play a key role in concrete quality and must be analyzed in a microscopic point of view. This research studies the quality of high performance concrete by taking drilled cores in both horizontal and vertical directions from a 1.0 m3 specimen. The coarse aggregate, expressed in digitized 100×116 dpi resolution images are processed based on brightness in colors through commercial software converted into text files. With the image converting to text format, the share of coarse aggregate is quantified leading to a satisfactory assessment of homogeneity – a quality index of high performance concrete. The compressive strengths of concrete and the shares of coarse aggregate of the samples are also compared in this research study to illustrate its correlation in concrete quality. It is concluded that a higher homogeneity of aggregate exists in the vertical plane than that of the horizontal planes of the high performance concrete. In addition, the concrete specimen showing denser particle packing has relatively higher compressive strengths. The research methodology provides an easy-to-use, direct measurement of high performance concrete when conducting quality assessment in the construction site.