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41.
42.
Min-Kyung Kang Soo-Il Kim Su Yeon Oh Woojin Na Young-Hee Kang 《International journal of molecular sciences》2020,21(22)
Podocyte injury inevitably results in leakage of proteins from the glomerular filter and is vital in the pathogenesis of diabetic nephropathy (DN). The underlying mechanisms of podocyte injury facilitate finding of new therapeutic targets for DN treatment and prevention. Tangeretin is an O-polymethoxylated flavone present in citrus peels with anti-inflammatory and antioxidant properties. This study investigated the renoprotective effects of tangeretin on epithelial-to-mesenchymal transition-mediated podocyte injury and fibrosis through oxidative stress and hypoxia caused by hyperglycemia. Mouse podocytes were incubated in media containing 33 mM glucose in the absence and presence of 1–20 μM tangeretin for up to 6 days. The in vivo animal model employed db/db mice orally administrated with 10 mg/kg tangeretin for 8 weeks. Non-toxic tangeretin inhibited glucose-induced expression of the mesenchymal markers of N-cadherin and α-smooth muscle actin in podocytes. However, the reduced induction of the epithelial markers of E-cadherin and P-cadherin was restored by tangeretin in diabetic podocytes. Further, tangeretin enhanced the expression of the podocyte slit diaphragm proteins of nephrin and podocin down-regulated by glucose stimulation. The transmission electron microscopic images revealed that foot process effacement and loss of podocytes occurred in diabetic mouse glomeruli. However, oral administration of 10 mg/kg tangeretin reduced urine albumin excretion and improved foot process effacement of diabetic podocytes through inhibiting loss of slit junction and adherenes junction proteins. Glucose enhanced ROS production and HIF-1α induction in podocytes, leading to induction of oxidative stress and hypoxia. Similarly, in diabetic glomeruli reactive oxygen species (ROS) production and HIF-1α induction were observed. Furthermore, hypoxia-evoking cobalt chloride induced epithelial-to-mesenchymal transition (EMT) process and loss of slit diaphragm proteins and junction proteins in podocytes, which was inhibited by treating submicromolar tangeretin. Collectively, these results demonstrate that tangeretin inhibited podocyte injury and fibrosis through blocking podocyte EMT caused by glucose-induced oxidative stress and hypoxia. 相似文献
43.
Joon‐Seop Kim Min‐Chul Hong Yeon Hwa Nah Yeonhee Lee Seunghee Han Hyun Eui Lim 《应用聚合物科学杂志》2002,83(11):2500-2504
The wetting properties of polystyrene‐based ionomers treated with plasma source ion implantation (PSII) were investigated by the measurement of water contact angles. When sulfonated ionomers were aged for a few days, the hydrophobic recovery for the ionomers became much slower than that for the nonionic polymers. However, when the samples were aged over 20 days, the water contact angle of the ionomers converged with that of the nonionic polymer. Thus, it was concluded that the ionic interaction between the ionic groups and the presence of ionic groups together resulted in the slow hydrophobic recovery and that the aging effect was significant for the ionomers. For the methacrylate ionomer of low ion content, on the other hand, it was found that the PSII treatment produced only a small change in hydrophobic recovery behavior. Thus, it was suggested that the low ionic content coupled with the small size of the ionic unit might cause changes only of a very insignificant degree in hydrophobic recovery behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2500–2504, 2002 相似文献
44.
Seong Ik Yoo Tae Yeon Lee Jin‐San Yoon Ik‐Mo Lee Mal‐Nam Kim Han Sup Lee 《应用聚合物科学杂志》2002,83(4):767-776
The interfacial reaction of the polyethylene (PE)/starch blend system containing the reactive compatibilizer maleated polyethylene (m‐PE) was directly characterized by Fourier transform infrared (FTIR) spectroscopy. A significant amount of anhydride groups on m‐PE existed as hydrolyzed forms, resulting in a large amount of carboxyl groups. Using a vacuum‐heating‐cell designed in the laboratory, the carboxyl groups were successfully transformed into the dehydrolyzed state (i.e., anhydride group). This result enabled the direct spectroscopic observation of chemical reaction occurring at the interface. For the PE/starch blend system containing m‐PE, the chemical reaction at the interface was verified by the evolution of ester and carboxyl groups in the FTIR spectra. The effect of the reactive compatibilizer on the interfacial morphology was also examined by scanning electron micrography (SEM). Enhanced interfacial adhesion was clearly observed for the blend system containing reactive compatibilizer. Tensile strengths of blend systems containing m‐PE also increased noticeably compared with the corresponding system without compatibilizer. A similar observation was made for the breaking elongation data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 767–776, 2002 相似文献
45.
Soon-Ho Kwon Youn-Ki Jun Seong-Hyeon Hong In-Seop Lee Hyoun-Ee Kim Ye Yeon Won 《Journal of the American Ceramic Society》2002,85(12):3129-3131
Porous bioceramics, such as hydroxyapatite (HA), tricalcium phosphate (TCP), and biphasic HA/TCP, were fabricated using the polyurethane sponge technique. The porosity of the ceramics was controlled by a multiple coating of the porous body. When a porous body was produced by a single coating, the porosity was ∼90%, and the pores were completely interconnected. When the sintered body was coated five times after the porous network had been made, the porosity decreased to 65%. As the porosity decreased, the strength increased exponentially. The TCP exhibited the highest dissolution rate in a Ringer's solution, and the HA had the lowest rate. The biphasic HA/TCP showed an intermediate dissolution rate. 相似文献
46.
Perron and Zhu (2005) established the consistency, convergence rate and limiting distributions of parameter estimates in time trends with a change in slope with or without a concurrent level change for the cases with I(1) or I(0) errors. We extend their analysis to the general case of fractionally integrated errors with memory parameter d?. Our results uncover interesting features; e.g., with a level shift allowed, the convergence rate for the break date estimate is the same for all d?∈(?0.5,0.5). In other cases, it is decreasing as d? increases. We also provide results about the so‐called spurious break issue. 相似文献
47.
Ji Yeon Ko Sin-Young Park Duk Yong Yoon Suk-Joong L. Kang 《Journal of the American Ceramic Society》2004,87(12):2262-2267
When TiC–20 wt% Ni powder mixtures are sintered at 1400°C, relatively large TiC grains possibly containing some Ni form with near-equilibrium shapes. When these specimens are heat-treated again at 1400°C in contact with sintered WC–20 wt% Ni pieces, the liquid films between the TiC grains in the contact region migrate against their increasing curvatures, forming (Ti,W)C solid solution behind them. These migrating liquid films reverse their directions on further heat-treatment. As in other alloys, this liquid film migration must be driven by the coherency strain energy produced by W diffusion at the surface of the dissolving TiC grains. Shells of (Ti,W)C solid solution also form around the cores of TiC grains near the contact region, and this process is probably driven by both coherency strain energy and free energy of mixing. At some contact regions, (Ti,W)C precipitates nucleate and grow, probably driven mainly by the free energy of mixing. In powder mixtures, the formation of core-shell grains is expected to be driven by the coherency strain energy, the free energy of mixing, and the capillary effect. 相似文献
48.
Bo-Hyuk Jang Tae-Hun Yeon Hyun-Sik Han Yong-Ki Park Jae-Eui Yie 《Catalysis Letters》2001,77(1-3):21-28
Barium-containing NO
x
storage catalyst showed serious deactivation under thermal exposure at high temperatures. To elucidate the thermal deterioration of the NO
x
storage catalyst, four types of model catalyst, Pt/Al2O3, Ba/Al2O3, Pt–Ba/Al2O3, and a physical mixture of Pt/Al2O3 + Ba/Al2O3 were prepared and their physicochemical properties such as BET, NO TPD, TGA/DSC, XRD, and XPS were evaluated while the thermal aging temperature was increased from 550 to 1050°C. The fresh Pt–Ba/Al2O3 showed a sorption capacity of 3.35 wt%/g-cat. but the aged one revealed a reduced capacity of 2.28 wt%/g-cat. corresponding to 68% of the fresh one. It was found that this reduced sorption capacity was directly related to the deterioration of the NO
x
storage catalyst by thermal aging. The Ba on Ba/Al2O3 and Pt–Ba/Al2O3 catalysts began to interact with alumina to form Ba–Al solid alloy above 600°C and then transformed into stable BaAl2O4 having a spinel structure. However, no phase transition was observed in the Pt/Al2O3 catalyst having no barium component, even after aging at 1050°C. 相似文献
49.
Bo-Hyuk Jang Tae-Hun Yeon Hyun-Sik Han Yong-Ki Park Jae-Eui Yie 《Catalysis Letters》2001,77(4):255-258
Authors Index
Author Index 相似文献50.
Yeon Kim Su-Ji Jang Hyeung-Rak Kim Seon-Bong Kim 《Korean Journal of Chemical Engineering》2017,34(5):1400-1404
We evaluated the deodorizing activities of polyphenolics against methyl mercaptan and their inhibitory activity on Streptococcus mutans, Candida albicans, and glucosyltransferase responsible for oral health. Polyphenolics including eckol, dieckol, catechol, catechin, phloroglucinol, chlorogenic acid, epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC), caffeic acid, and tannic acid were used to investigate their deodorizing, antimicrobial and enzyme activity. Among the polyphenolics, dieckol, eckol, and catechol showed higher deodorizing activity against methyl mercaptan than sodium copper chlorophyllin known as a commercial deodorant. Catechol, dieckol, and eckol exhibited a strong antimicrobial activity on S. mutans, while cinnamic acid, caffeic acid, and catechol showed a strong antifungal activity on C. albicans compared to other polyphenolics. Tannic acid, ECG, and dieckol strongly inhibited the activity of the glucosyltransferase produced by Streptococcus mutans. 相似文献