910 research outputs found

    What Questions do People Ask on a Human Papillomavirus Website? A Comparative Analysis of Public and Private Questions

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    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

    Ru-Catalyzed, cis-Selective Living Ring-Opening Metathesis Polymerization of Various Monomers, Including a Dendronized Macromonomer, and Implications to Enhanced Shear Stability

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    An unsaturated polymer’s cis/trans-olefin content has a significant influence on its properties. For polymers obtained by ring-opening metathesis polymerization (ROMP), the cis/trans-olefin content can be tuned by using specific catalysts. However, cis-selective ROMP has suffered from narrow monomer scope and lack of control over the polymerization (giving polymers with broad molecular weight distributions and prohibiting the synthesis of block copolymers). Herein, we report the versatile cis-selective controlled living ROMP of various endo-tricyclo[4.2.2.0^(2,5)]deca-3,9-diene and various norbornene derivatives using a fast-initiating dithiolate-chelated Ru catalyst. Polymers with cis-olefin content as high as 99% could be obtained with high molecular weight (up to M_n of 105.1 kDa) and narrow dispersity (<1.4). The living nature of the polymerization was also exploited to prepare block copolymers with high cis-olefin content for the first time. Furthermore, owing to the successful control over the stereochemistry and narrow dispersity, we could compare cis- and trans-rich polynorbornene and found the former to have enhanced resistance to shear degradation

    The Analysis of Antecedents for the Video Telephony Service Adoption: From the Value-Based Perspective

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    Korean Telecommunications Industry has a large scale market and boasts on high service quality and high technologies enough to provide the Video Telephony Service (VTS) satisfactorily. For many years, Korean telephone companies have been investing enormous sums to advertise their services widely and to allow their customers to change their cell phones for the third-generation (3G) devices indispensable for the service. However, despite their efforts, the VTS adoption rate in Korea is very low and it seems that customers seldom feel the necessity to use. From this viewpoint, it becomes necessary to find the antecedents influencing the intention to use for the VTS empirically. For this purpose, we proposed several hypotheses from the perspective of the Value-based Adoption Model (VAM). VAM is a conceptual model suggested to overcome some limitations of the Technology Acceptance Model (TAM) in explaining the adoption of new Information and Communication Technology (ICT) such as Mobile Internet where customers play the role of service consumer rather than simply technology users. We conducted a survey on 125 samples and found that customers perceive the value of VTS when they can recognize the service is functionally useful (Perceived Usefulness) and when they feel they can put themselves forward by using it (Self-Expression). On the other hand, the other factors including Technical Complexity, Privacy Concern and Perceived Price (Fee) don’t have statistically significant influences on the Perceived Value of VTS

    Unleashing the full potential of Hsp90 inhibitors as cancer therapeutics through simultaneous inactivation of Hsp90, Grp94, and TRAP1

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    Cancer therapeutics: Extending a drug&apos;s reach A new drug that blocks heat shock proteins (HSPs), helper proteins that are co-opted by cancer cells to promote tumor growth, shows promise for cancer treatment. Several drugs have targeted HSPs, since cancer cells are known to hijack these helper proteins to shield themselves from destruction by the body. However, the drugs have had limited success. Hye-Kyung Park and Byoung Heon Kang at Ulsan National Institutes of Science and Technology in South Korea and coworkers noticed that the drugs were not absorbed into mitochondria, a key cellular compartment, and HSPs in this compartment were therefore not being blocked. They identified a new HSP inhibitor that can reach every cellular compartment and inhibit all HSPs. Testing in mice showed that this inhibitor effectively triggered death of tumor cells, and therefore shows promise for anti-cancer therapy. The Hsp90 family proteins Hsp90, Grp94, and TRAP1 are present in the cell cytoplasm, endoplasmic reticulum, and mitochondria, respectively; all play important roles in tumorigenesis by regulating protein homeostasis in response to stress. Thus, simultaneous inhibition of all Hsp90 paralogs is a reasonable strategy for cancer therapy. However, since the existing pan-Hsp90 inhibitor does not accumulate in mitochondria, the potential anticancer activity of pan-Hsp90 inhibition has not yet been fully examined in vivo. Analysis of The Cancer Genome Atlas database revealed that all Hsp90 paralogs were upregulated in prostate cancer. Inactivation of all Hsp90 paralogs induced mitochondrial dysfunction, increased cytosolic calcium, and activated calcineurin. Active calcineurin blocked prosurvival heat shock responses upon Hsp90 inhibition by preventing nuclear translocation of HSF1. The purine scaffold derivative DN401 inhibited all Hsp90 paralogs simultaneously and showed stronger anticancer activity than other Hsp90 inhibitors. Pan-Hsp90 inhibition increased cytotoxicity and suppressed mechanisms that protect cancer cells, suggesting that it is a feasible strategy for the development of potent anticancer drugs. The mitochondria-permeable drug DN401 is a newly identified in vivo pan-Hsp90 inhibitor with potent anticancer activity

    Cytoprotective Activity of Glycyrrhizae radix Extract Against Arsenite-induced Cytotoxicity

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    Licorice, Glycyrrhizae radix, is one of the herbal medicines in East Asia that has been commonly used for treating various diseases, including stomach disorders. This study investigated the effect of licorice on arsenite (As)-induced cytotoxicity in H4IIE cells, a rat hepatocyte-derived cell line. Cell viability was significantly diminished in As-treated H4IIE cells in a time and concentration-dependent manner. Furthermore, results from flow cytometric assay and DNA laddering in H4IIE cells showed that As treatment induced apoptotic cell death by activating caspase-3. Licorice (0.1 and 1.0 mg ml−1) treatment significantly inhibited cell death and the activity of caspase-3 in response to As exposure. These results demonstrate that licorice induced a cytoprotective effect against As-induced cell death by inhibition of caspase-3

    Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin film

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    Transition metal oxide thin films show versatile electrical, magnetic, and thermal properties which can be tailored by deliberately introducing macroscopic grain boundaries via polycrystalline solids. In this study, we focus on the modification of the magnetic and thermal transport properties by fabricating single- and polycrystalline epitaxial SrRuO3 thin films using pulsed laser epitaxy. Using epitaxial stabilization technique with atomically flat polycrystalline SrTiO3 substrate, epitaxial polycrystalline SrRuO3 thin film with crystalline quality of each grain comparable to that of single-crystalline counterpart is realized. In particular, alleviated compressive strain near the grain boundaries due to coalescence is evidenced structurally, which induced enhancement of ferromagnetic ordering of the polycrystalline epitaxial thin film. The structural variations associated with the grain boundaries further reduce the thermal conductivity without deteriorating the electronic transport, and lead to enhanced thermoelectric efficiency in the epitaxial polycrystalline thin films, compared with their single-crystalline counterpart.Comment: 24 pages, 5 figure

    Preparation and evaluation of polymeric microparticulates for improving cellular uptake of gemcitabine

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    Ji-Ho Lim1,*, Sung-Kyun You1,*, Jong-Suep Baek1, Chan-Ju Hwang1, Young-Guk Na1, Sang-Chul Shin2, Cheong-Weon Cho11College of Pharmacy and Institute of Drug Research and Development, Chungnam National University, Gungdong, Yuseonggu, Daejeon, South Korea, 2College of Pharmacy, Chonnam National University, Buggu, Gwangju, South Korea *These authors contributed equally to this workBackground: Gemcitabine must be administered at high doses to elicit the required therapeutic response because of its very short plasma half-life due to rapid metabolism. These high doses can have severe adverse effects.Methods: In this study, polymeric microparticulate systems of gemcitabine were prepared using chitosan as a mucoadhesive polymer and Eudragit L100-55 as an enteric copolymer. The physicochemical and biopharmaceutical properties of the resulting systems were then evaluated.Results: There was no endothermic peak for gemcitabine in any of the polymeric gemcitabine microparticulate systems, suggesting that gemcitabine was bound to chitosan and Eudragit L100-55 and its crystallinity was changed into an amorphous form. The polymeric gemcitabine microparticulate system showed more than 80% release of gemcitabine in 30 minutes in simulated intestinal fluid. When mucin particles were incubated with gemcitabine polymeric microparticulates, the zeta potential of the mucin particles was increased to 1.57 mV, indicating that the polymeric gemcitabine microparticulates were attached to the mucin particles. Furthermore, the F53 polymeric gemcitabine microparticulates having 150 mg of chitosan showed a 3.8-fold increased uptake of gemcitabine into Caco-2 cells over 72 hours compared with gemcitabine solution alone.Conclusion: Overall, these results suggest that polymeric gemcitabine microparticulate systems could be used as carriers to help oral absorption of gemcitabine.Keywords: gemcitabine, polymeric microparticulates, mucoadhesive, enteric coating, cellular uptake, oral absorptio
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