http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Kim, Taeyoon,Mays, Jimmy,Chung, Ildoo Elsevier 2018 Polymer Vol.158 No.-
<P><B>Abstract</B></P> <P>Porous biodegradable microspheres were fabricated by successful RAFT polymerization of methyl vinyl ketone onto polycaprolactone followed by an oil/water emulsion-evaporation method, then finally photodegradation of PMVK blocks by UV irradiation. Macro-CTA (chain transfer agent) was synthesized by reacting carboxylic acid-terminated CTA, S-1-dodecyl-S’-(α,α′-dimethyl-α’‘-acetic acid) trithiocarbonate (DDMAT) with hydroxyl terminated polycaprolactone, which was then used for the synthesis of triblock copolymer with methyl vinyl ketone (MVK). The synthesized triblock copolymers were characterized by FT-IR, <SUP>1</SUP>H NMR spectroscopies. Gel permeation chromatography (GPC) was used to evaluate the molecular weight and molecular weight distribution and monitored the photodegradability of the block copolymers. The morphology of microspheres was spherical with smooth surfaces before UV irradiation. However, those from PCL-PMVK triblock copolymers had rough surfaces and porous structures after UV irradiation due to the photodegradation of PMVK blocks as a porous template. The porosity and shape of the microspheres and shape of microspheres were dependent on the PMVK contents and size of microspheres.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Successful RAFT polymerization of triblock copolymers from methyl vinyl ketone onto polycaprolactone. </LI> <LI> Fabrication of porous microspheres by emulsion-evaporation method, followed by the photodegradation of PMVK blocks. </LI> <LI> Novel methods for direct templating fabrication of porous polymers by removing template blocks by UV light. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Y.,Han, B.,Titlow, W.,Mays, C.E.,Kwon, M.,Ryou, C. Elsevier/North-Holland 2009 Antiviral research Vol.84 No.2
Prion diseases are incurable, transmissible neurodegenerative disorders in humans and animals. Because the disease-associated isoform of prion protein, PrP<SUP>Sc</SUP>, is conformationally converted from cellular prion protein, PrP<SUP>C</SUP>, knockdown of PrP<SUP>C</SUP> expression by RNA interference (RNAi) implicates therapy for prion diseases. In this study, introduction of small interfering (si) and small hairpin (sh) RNAs targeting the prion protein gene (prnp) transcripts triggered specific gene silencing and reduced the PrP<SUP>C</SUP> level in both prion-free and -infected neuroblastoma cell lines. Furthermore, this approach suppressed PrP<SUP>Sc</SUP> formation and ultimately eliminated PrP<SUP>Sc</SUP> from prion-infected cell lines. However, prolonged culture of cured cells resulted in reappearance of PrP<SUP>Sc</SUP> in the cell population, presumably by de novo PrP<SUP>Sc</SUP> formation from residual PrP<SUP>C</SUP> uncontrolled by RNAi and PrP<SUP>Sc</SUP> remained under the detection limit. Protein misfolding cyclic amplification assays further confirmed that lysate of cured cells was sufficient to support PrP<SUP>Sc</SUP> propagation. Our data not only suggest a potential treatment option but also implicate a caveat for using an RNAi approach for prion diseases. These findings provide critical information required to advance RNAi-based prevention and therapy for prion diseases of humans and animals.
Worlanyo E. Gato,Daniel A. Hunter,Shamaya L. Whitby,Christopher A. Mays,Wilson Yau 대한당뇨병학회 2016 Diabetes and Metabolism Journal Vol.40 No.6
Background In recent times, there has been an increase in the incidence of type 2 diabetes mellitus (T2DM) particularly in children. Adipocyte dysfunction provide a critical link between obesity and insulin resistance resulting in diabetes outcome. Further, environmental chemical exposure during early years of life might be a significant contributing factor to the increase in the incidence of T2DM. This study tests the idea that exposure to environmental contaminants (2-aminoanthracene [2AA]) in utero will show effects in the adipose tissue (AT) that signify T2DM vulnerability. 2AA is a polycyclic aromatic hydrocarbon found in a variety of products. Methods To accomplish the study objective, pregnant dams were fed various amounts of 2AA adulterated diets from gestation through postnatal period. The neonates and older offspring were analyzed for diabetic-like genes in the ATs and analysis of serum glucose. Furthermore, weight monitoring, histopathology and immunohistochemical (IHC) staining for CD68 in AT, adipocyte size determination and adiponectin amounts in serum were undertaken. Results Up-regulation of adiponectin and interleukin-6 genes were noted in the pups and older rats. Combination of intrauterine 2AA toxicity with moderate high fat diet exhibited gene expression patterns similar to those of the neonates. Elevated serum glucose levels were noted in treated groups. IHC of the AT indicated no significant malformations; however, CD68+ cells were greater in the animals treated to 2AA. Similarly, mean sizes of the adipocytes were larger in treated and combined 2AA and moderate high fat animals. Adiponectin was reduced in 2AA groups. Conclusion From the preceding, it appears intrauterine 2AA disturbance, when combined with excess fat accumulation will lead to greater risk for the diabetic condition.
Goodwin, Andrew,Goodwin, Kimberly M.,Wang, Weiyu,Yu, Yong-Guen,Lee, Jae-Suk,Mahurin, Shannon M.,Dai, Sheng,Mays, Jimmy W.,Kang, Nam-Goo American Chemical Society 2016 Macromolecules Vol.49 No.17
<P>Anionic polymerization is one of the most powerful techniques for preparation of well-defined polymers. However, this well-known and widely employed polymerization technique encounters major limitations for the polymerization of functional monomers containing heteroatoms. This work presents the anionic polymerization of 2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole (VPyOzP), a heteroatom monomer that contains both oxadiazole and pyridine substituents within the same pendant group, using various initiating systems based on diphenylmethyl potassium (DPM-K) and triphenylmethyl potassium (TPM-K). Remarkably, well-defined poly(2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole) (PVPyOzP) polymers having predicted molecular weights (MW) ranging from 2200 to 21 100 g/mol and polydispersity indices (PDI) ranging from 1.11 to 1.15 were prepared with TPM-K, without any additional additives, at -78 degrees C. The effect of temperature on the polymerization of PVPyOzP was also studied at -78, -45, 0, and 25 degrees C, and it was observed that increasing the polymerization temperature produced materials with unpredictable MWs and broader molecular weight distributions. Furthermore, the nucleophilicity of PVPyOzP was investigated through copolymerization with methyl methacrylate and acrylonitrile, where only living poly(methyl methacrylate) (PMMA) prepared by DPM-K/VPPy and in the absence of additives such as lithium chloride (LiCl) and diethyl zinc (ZnEt2) could be used to produce the well-defined block copolymer of PMMA-b-PVPyOzP. It was also demonstrated by sequential monomer addition that the nucleophilicity of living PVPyOzP is located between that of living PMMA and polyacrylonitrile (PAN). The pyridine moiety of the pendant group also allowed for quaternization and produced PQVPyOzP homopolymer using methyl iodide (CH3I) and bis(trifluoromethylsulfonyl)amide [Tf2N ]. The resulting charged polymer and counterion complexes were manipulated and investigated for potential use as membranes for carbon dioxide (CO2) capture.</P>