- 著者
- Athchaya SUWANSOONTORN Katsuhiro YAMAMOTO Shusaku NAGANO Jun MATSUI Yuki NAGAO
- 出版者
- The Electrochemical Society of Japan
- 雑誌
- Electrochemistry (ISSN:13443542)
- 巻号頁・発行日
- pp.21-00042, (Released:2021-05-21)
- 参考文献数
- 47
- 被引用文献数
- 2
Investigation of interfacial proton transport is necessary to elucidate biological systems. As commonly found in biomaterials, the carboxylic acid group was proven to act as a proton-conducting group. This study investigated the influence of carboxylic acid concentration on both interfacial and internal proton transport. Several styrene-based polymers containing the carboxylic acid group were synthesized. The amount of carboxylic acid group in the polymer chain was varied to explore the effects of weak acid concentration on polymer thin films’ electrical properties. The IR p-polarized multiple-angle incidence resolution spectrometry (pMAIR) spectra show the higher ratio of the free carboxylic acid groups rather than cyclic dimers in polymers with a higher concentration of carboxylic acid group, facilitating the more hydrogen bonding networks in films. The water uptake results reveal the similar number of adsorbed water molecules per carboxylic acid group in all thin films. Remarkably, polymer thin films with high carboxylic acid concentration provide internal proton conduction because of the relative increase in the amount of the free carboxylic acid group. In contrast, interfacial proton conduction was found in low carboxylic acid concentration polymers because of the relatively large amount of cyclic dimer carboxylic acid group and poor amount of free carboxylic acid group. This study provides insight into interfacial proton transport behavior according to the weak acid concentration, which might explain proton transport in biological systems.
- 著者
- Maki Yamashita Naoki Tamasawa Kota Matsuki Jutaro Tanabe Hiroshi Murakami Jun Matsui Toshihiro Suda
- 出版者
- Japan Atherosclerosis Society
- 雑誌
- Journal of Atherosclerosis and Thrombosis (ISSN:13403478)
- 巻号頁・発行日
- vol.17, no.11, pp.1183-1189, 2010 (Released:2010-11-27)
- 参考文献数
- 37
- 被引用文献数
- 8 19
Aims: We studied the effect of insulin on HDL-mediated cholesterol efflux from macrophages. The potential involvement of cholesteryl ester hydrolysis and membrane cholesterol transport was also addressed.Methods: Human monocyte-derived THP-1 cells were developed into macrophages. Cholesterol efflux was measured by incubating macrophages, labeled with [3H]-cholesterol, with HDL for 24 h. The cells were treated with insulin (0-500 nM) for 30 min prior to the addition of HDL. To investigate the molecular mechanisms of the effect of insulin, the expressions of neutral cholesteryl ester hydrolase (nCEH) and ATP-binding cassette transporter (ABC) G1 were analyzed.Results: Insulin inhibited, in a concentration-dependent manner, HDL-mediated cholesterol efflux from macrophages. Insulin also inhibited the enzyme activity of nCEH and its mRNA and protein expression in cells. Insulin also suppressed the expressions of mRNA and protein for ABCG1.Conclusions: Insulin inhibits HDL-mediated cholesterol efflux from macrophages, which may result from the suppression of nCEH and ABCG1 expressions. Our findings show part of the potential molecular mechanism of atherogenesis in type 2 diabetes with hyperinsulinemia.