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81.
A total synthesis of (-)-histrionicotoxin was achieved. Our synthesis features preparation of a pseudosymmetrical dienyne through chirality transfer from an allenylsilane, a dienyne metathesis to produce the bicyclo [5.4.0] system in optically active form, selective functionalization of a diene via a 5-exo-trig iodoetherification, and an asymmetric propargylation. 相似文献
82.
Using an organic p/n bilayer comprised of 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole (PTCBI, an n-type semiconductor) and 29H,31H-phthalocyanine (H2Pc, a p-type semiconductor) as a photoanode in the presence of FeII(CN)64? (an electron donor), the oxidation kinetics on the H2Pc surface was investigated with respect to the pHs employed (i.e. pH = 4, 7, and 10). The kinetic analysis of the rate-limiting charge transfer between H2Pc and FeII(CN)64? was conducted by assuming the Langmuir adsorption equilibrium at the H2Pc/water interface. In addition to a demonstration of the PTCBI/H2Pc photoanode under the weakly acidic–alkaline conditions, the present work evidently shows that the photoanodic reaction is kinetically independent of the pH conditions employed. 相似文献
83.
Shikata T Iseki M Matsunaga S Higashi S Kamei Y Watanabe M 《Photochemistry and photobiology》2011,87(3):590-597
Photophysiological and pharmacological approaches were used to examine light-induced germination of resting spores in the red-tide diatom Leptocylindrus danicus. The equal-quantum action spectrum for photogermination had peaks at about 440 nm (blue light) and 680 nm (red light), which matched the absorption spectrum of the resting spore chloroplast, as well as photosynthetic action spectra reported for other diatoms. DCMU, an inhibitor of photosynthetic electron flow near photosystem II, completely blocked photogermination. These results suggest that the photosynthetic system is involved in the photoreception process of light-induced germination. Results of pharmacological studies of the downstream signal transduction pathway suggested that Ca(2+) influx is the closest downstream neighbor, followed by steps involving calmodulin, nitric oxide synthase, guanylyl cyclase, protein-tyrosine-phosphatase, protein kinase C and actin polymerization and translation. 相似文献
84.
Masao Yamasaki Yumi Yamasaki Rina Furusho Hayaka Kimura Ichiro Kamei Hiroko Sonoda Masahiro Ikeda Tatsuya Oshima Kenjiro Ogawa Kazuo Nishiyama 《Molecules (Basel, Switzerland)》2021,26(9)
The aim of this study was to evaluate the involvement of nanoparticles prepared from Allium cepa L. as anti-inflammatory agents. In the present study, we identified nanoparticles from Allium cepa L. using the ultracentrifugation exosome purification method. The nanoparticles were referred to as 17,000× g and 200,000× g precipitates, and they contained quercetins, proteins, lipids, and small-sized RNA. The nanoparticles inhibited nitric oxide production from lipopolysaccharide (LPS)-stimulated RAW264 cells without cytotoxic properties. Cellular incorporation was confirmed by laser microscopic observation after PKH26 staining. The inhibition of caveolae-dependent endocytosis and macropinocytosis significantly prevented the incorporation of the nanoparticles but had no effect on the inhibition of nitric oxide in RAW264 cells. Collectively, the identified nanoparticles were capable of inhibiting the LPS response via extracellular mechanisms. Taken together, the way of consuming Allium cepa L. without collapsing the nanoparticles is expected to provide an efficient anti-inflammatory effect. 相似文献
85.
Yasutaka Kamei Atsushi Sudo Haruo Nishida Kiyoshi Kikukawa Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(7):2525-2535
A series of activated urethane‐type derivatives of α‐amino acids were synthesized and applied to polypeptide synthesis. The urethane used herein, N‐(4‐nitrophenoxycarbonyl)‐α‐amino acids 1 , were synthesized by N‐carbamoylation of γ‐benzyl‐L ‐glutamate, β‐benzyl‐L ‐aspartate, L ‐leucine, L ‐phenylalanine, and L ‐proline, with 4‐nitrophenyl chloroformate. When 1 was dissolved in N,N‐dimethylacetamide (DMAc) and heated at 60 °C, it was smoothly converted into the corresponding polypeptides with releasing 4‐nitrophenol and carbon dioxide. Spectroscopic analyses of the obtained polypeptides revealed that they were comparable with the authentic polypeptides synthesized by the ring‐opening polymerizations of amino acid N‐carboxyanhydrides (NCAs). Besides the successful polycondensations of a series of 1 , their polycondensations of 1a and other 1 were also successfully carried out to obtain the corresponding statistic copolypeptides. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2525–2535, 2008 相似文献
86.
Yasutaka Kamei Atsushi Nagai Atsushi Sudo Haruo Nishida Kiyoshi Kikukawa Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(8):2649-2657
A series of activated urethane‐type derivatives of γ‐benzyl‐L ‐glutamate were synthesized, and their potential as monomers for polypeptide synthesis was investigated. The derivatives of the focus of this work were a series of N‐aryloxycarbonyl‐γ‐benzyl‐L ‐glutamate 1 , of which aryl groups were phenyl, 4‐chlorophenyl, and 4‐nitrophenyl. These urethanes 1 were reactive in polar solvents such as dimethylsulfoxide, N,N‐dimethylformamide (DMF), and N,N‐dimethylacetamide (DMAc), and were efficiently converted into poly(γ‐benzyl‐L ‐glutamate) (poly(BLG)) under mild conditions; at 60 °C without addition of any catalyst. Among the three urethanes, that having 4‐nitrophenoxycarbonyl group 1c was the most reactive to give poly(BLG) efficiently, as was expected from the highly electron deficient nature of the nitrophenoxycarbonyl group. On the other hand, the urethane 1a having phenoxycarbonyl group was also efficiently converted into poly(BLG), in spite of the intrinsically less electrophilicity of the phenoxycarbonyl group. In addition, the successful formation of poly(BLG) by the reaction of 1a favored its diluted concentration (0.1 M) much more than 2.0 M, the optimum initial concentration for 1c . 1H NMR spectroscopic analyses of the reactions in situ revealed that the predominant pathway from 1 to poly(BLG) involved the intramolecular cyclization of 1 into the corresponding N‐carboxyanhydride, with release of phenol and its successive ring‐opening polymerization with release of carbon dioxide. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2649–2657, 2008 相似文献
87.
Satoshi Kamei 《Discrete Mathematics》2007,307(24):3201-3206
Constructibility is a combinatorial property of simplicial complexes. In general, it requires a great deal of time to decide whether a simplicial complex is constructible or not. In this paper, we consider sufficient conditions for nonconstructibility of simplicial 3-balls to investigate efficient algorithms for the decision problem. 相似文献
88.
89.
Let A?B?0 with A>0, t∈[0,1] and p?1. Then we shall show that
90.
H Harada Y Ueno M Kamei R Ohura N Tanabe Y Uchida F Koyama T Yamaguchi 《Biomedical chromatography : BMC》1989,3(3):110-113
Fluorescein isothiocyanate (FITC)-labelled asialotransferrin and pyridyl aminated oligosaccharides were prepared from asialotransferrin and human milk using affinity chromatography and high performance liquid chromatography (HPLC), respectively. These substances were incubated with galactosidase or sialyltransferase and then examined by lectin affinity HPLC. The elution patterns changed according to the period of incubation and amount of enzyme. This analytical method using lectin affinity HPLC with fluorescence labelled glycoprotein or oligosaccharides as the substrates has great value for detecting these enzyme under the same chromatographic conditions. In addition, differences were noted in the activity of beta-galactosidase toward oligosaccharides having the Gal beta(1----3)GlcNAc or Gal beta(1----4)GlcNAc structure at reducing termini. 相似文献