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51.
N Cho Y Nara M Harada T Sugo Y Masuda A Abe K Kusumoto Y Itoh T Ohtaki T Watanabe S Furuya 《Canadian Metallurgical Quarterly》1998,46(11):1724-1737
On the basis of structural information for the cyclic hexapeptide endothelin (ET) receptor antagonist, TAK-044, a series of thieno[2,3-d]pyrimidine-2,4-dione derivatives bearing a carboxyl group and aromatic rings that were important for receptor binding were designed, synthesized, and evaluated for ET receptor binding affinities and inhibitory activities against ET-induced vasoconstriction. Optimization of each substituent in the thieno[2,3-d]pyrimidine ring led to the discovery of a novel and potent nonpeptide ET receptor antagonist, 6-(4-methoxymethoxyphenyl)-5-methylsulfonylaminomethyl-1-(2- methylthiobenzyl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]p yrimidine-3- acetic acid (32 g), which binded to human ETA and ETB receptor subtypes with affinities (IC50) of 7.6 and 100 nM, respectively. Compound 32 g effectively antagonized ET-induced vasoconstriction and the inhibitory effect mediated by the ETB receptor was more potent than that of bosentan, while the inhibitory effect mediated by the ETA receptor was slightly less potent than that of bosentan. 相似文献
52.
A Ozaki M Kitano N Itoh K Kuroda N Furusawa T Masuda H Yamaguchi 《Canadian Metallurgical Quarterly》1998,36(9-10):811-817
Five synthetic food colours Food Red Nos 3, 40 and 102 and Food Blue Nos 1 and 2, and their UV irradiated products were tested for mutagenic activity by means of the Ames test using Salmonella typhimurium strains TA98 and TA100. Food colours were irradiated with UV light for 14 days. Food Red Nos 3, 40 and 102 and Food Blue No. 1 were non-mutagenic before and after irradiation. UV irradiated products of Food Blue No. 2 were mutagenic in TA98 with or without S-9 mix. The mutagenic activity increased with increasing irradiation period, reached maximum potency on day 6, and then decreased. Moreover, Food Blue No. 2 showed DNA-damaging activity after 14 days of irradiation in rec-assay using Bacillus subtilis strains H17 and M45. The capillary electrophoresis was applied for the analysis of UV irradiated products of Food Blue No. 2. The original peak of Food Blue No. 2 was decomposed into seven peaks after UV irradiation. 相似文献
53.
Different photoactivatable derivatives of toxin 3 (CTX) Naja naja siamensis were obtained after CTX reaction with N-hydroxysuccinimide esters of p-azidobenzoic, p-azidotetraflourobenzoic, p-benzoylbenzoic and p-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzoic acids. The ion-exchange HPLC profiles for the reaction products were very similar in four cases, with one predominant peak corresponding to the derivative containing the label at Lys23. After [125I]iodination, CTX photoactivatable derivatives were cross-linked to the nicotinic acetylcholine receptor from Torpedo californica under optimized conditions. The highest cross-linking yield (up to 16% of the bound toxin) was observed for azidobenzoyl-Lys23-CTX. Different receptor subunits were found to be labelled depending on the nature of the photoactivatable group: the azido derivatives labelled the gamma and delta subunits, benzoylbenzoyl derivative labelled the alpha and delta subunits, while p-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzoyl derivative reacted with alpha, gamma and delta subunits. The cross-linking experiments in the presence of varying concentrations of (+)-tubocurarine demonstrated that the Lys23-attached diazirinyl group contacts the delta and alpha subunits in one ligand-binding site, whereas at the other site, for another CTX molecule, the contacts of the Lys23-diazirinyl are with gamma and alpha subunits. This means that the central loop in the two CTX molecules binds at the alpha/gamma and alpha/delta interfaces. Calculation of the sterically possible displacement of diazirinyl nitrogen, basing on the known X-ray structure of CTX, showed that this value does not exceed 13 A. The results obtained favor the disposition of the ligand-binding sites at the subunit interfaces, with the distance between alpha and delta, or alpha and gamma subunits at these sites being not more than 13 A. 相似文献
54.
55.
Kajihara Akiro; Komooka Hitoshi; Kamiya Kenshu; Umeyama Hideaki 《Protein engineering, design & selection : PEDS》1993,6(6):615-620
Bovine pancreatic /S-trypsin (PDB ID-code: 1TPO) which is registeredin the Brookhaven Protein Data Bank (PDB) consists of four exons.The results of homology searches for each exon in the PDB showedthat homologous proteins were tonin (PDB ID-code: 1TON), ratmast cell protease (PDB ID-code: 3RP2_A), kaffikrein A (PDBID-code: 2PKA_B) and kallikrein A (2PKA_B) respectively. Thus,for the three-dimensional structure prediction of 1TPO, a chimeraprotein was constructed from the three proteins mentioned aboveand the 3-D structure prediction was performed using this chimerareference protein. The modelled structure of 1TPO was energeticallyoptimized by molecular mechanics and molecular dynamics simulationand was compared with its X-ray crystal structure registeredin the PDB. The root mean square deviations (r.m.s.d.) of mainchain atoms and the neighbouring active site (5 sphere fromHis57, AsplO2 and Serl95) between the modelled structure andthe X-ray structure were 1.66 and 0.94 respectively. Porcinepancreatic elastase (PDB ID-code: 3EST) which is registeredin the PDB was used as the reference protein and the modelledstructure from 3EST was also compared with the X-ray data. Ther.m.s.d. of main chain atoms and that of the active site were2.14 and 1.18 respectively. These results dearly support thepropriety of this method using the chimera reference protein. 相似文献
56.
Hideaki Itoh Shigeharu Naka Tsuneaki Matsudaira Hiroshi Hamamoto 《Journal of Materials Science》1990,25(1):533-536
A sintered compact of titanium diboride (TiB2) was prepared by hot pressing of the synthesized TiB2 powder, which was obtained by a solid-state reaction between TiN and amorphous boron. Densification of the sintered compact occurred at 20 MPa and 1800° C for 5 to 60 min with the aid of a reaction sintering, including the TiB2 formation reaction between excess 20 at % amorphous boron in the as-synthesized powder (TiB2 + 0.2B) and intentionally added 10 at % titanium metal. A homogeneous sintered compact of a single phase of TiB2, which was prepared by hot pressing for 30 min from the starting powder composition [(TiB2 + 0.2B) + 0.1 Ti], had a fine-grained microstructure composed of TiB2 grains with diameters of 2 to 3 m. The bulk density was 4.47 g cm–3, i.e. 98% of the theoretical density. The microhardness, transverse rupture strength and fracture toughness of the TiB2 sintered compact were 2850 kg mm–2, 48 kg mm–2 and 2.4 MN m–3/2, respectively. The thermal expansion coefficient increased with increasing temperature up to 400° C and had a constant value of 8.8 x 10–6 deg–1 above 500° C. 相似文献
57.
Hideaki Itoh Tsuneaki Matsudaira Shigeharu Naka Hiroshi Hamamoto 《Journal of Materials Science》1989,24(2):420-424
TiB2 powder was synthesized by a controlled formation reaction from titanium metal and amorphous boron. Precursory TiB2 formed by the pretreatment of the mixed powder (mole ratio: B/Ti=2.0) at 600° C for 60 min in an argon stream. Hollow TiB2 powder with an average grain size of 15m was obtained by subsequent heat treatment above 900° C for more than 60 min in an argon stream. The formation reaction of TiB2 powder was further controlled by pretreatment of the mixed powder at 600° C for 60 min in a hydrogen and argon stream and subsequent heat treatment at 1000° C for 360 min in an argon stream, when hollow-free TiB2 powder was formed by a milder formation reaction between amorphous boron and the reformed titanium metal with hydrogen diffused lattice. 相似文献
58.
T. Hioki A. Itoh M. Ohkubo S. Noda H. Doi J. Kawamoto O. Kamigaito 《Journal of Materials Science》1986,21(4):1321-1328
Sapphire plates, cut parallel to an {0001} plane, have been implanted with 300 keV nickel ions to doses ranging from 5×1012 to 1×1017 Ni cm–2 at specimen temperatures of 100, 300 and 523 K, in order to investigate the effect of implantation temperature on the mechanical property changes in sapphire caused by ion implantation. The measured changes in surface hardness, surface fracture toughness and bulk flexural strength were found to depend strongly on the implantation temperature, and were largely correlated with the residual surface compressive stress measured by using a cantilever beam technique. The surface amorphization that occurred only by the implantation at 100 K and at doses larger than 2×10s15 Ni cm–2 reduced the hardness to 0.6 relative to the value of the unimplanted sapphire, and considerably increased the surface plasticity. Furthermore, the amorphization was found to involve a large volume expansion of 30% and to change drastically the apparent shape and size of a Knoop indentation flaw made prior to implantation. This effect was suggested to reduce stress concentrations at surface flaws and hence to increase the flexural strength. 相似文献
59.
Atsushi Takahashi Isao Nakamura Masaaki Haneda Tadahiro Fujitani Hideaki Hamada 《Catalysis Letters》2006,106(3-4):133-138
Catalytic hydrogenation of naphthalene to decalin was studied over a carbon-supported rhodium catalyst in supercritical carbon
dioxide solvent at 333 K, and the results were compared with those in an organic solvent. cis-, trans-Decalin and tetralin were formed from the beginning of the reaction in supercritical carbon dioxide. Higher concentration
of hydrogen in carbon dioxide solvent and on the active site, and also the suppression of desorption of partially hydrogenated
tetralin molecules from the active site would be responsible for higher selectivity to cis-decalin in supercritical carbon dioxide than that in an organic solvent. 相似文献
60.
We have developed a reel-to-reel microchip mounting system that continuously mounts LED chips and other microchips on meter-long flexible printed circuit board (PCB) tape for 1.2-m-long standard LED light tubes. Mounting microchips on meter-long PCBs is difficult because a large chip mounter is expensive and the chip positioning stage is difficult to move in a meter-wide area with an accuracy of hundreds of micrometers. Hence, we developed a new microchip mounting system that utilizes a small chip mounter and reel winding machines. The system repeatedly moves the long PCB tape by a certain length with the reel winding machines and mounts the chips on it. The PCB tape (which is 5 mm wide) is made by fabricating long PCB tapes which are 25 cm × 26.6 m through a roll-to-roll PCB process and slitting them into meter-long tapes. The reel-to-reel system repeatedly mounts chips by adjusting their positions through image processing of the copper wiring pattern on the PCBs. Our constructed system mounted 24 LED chips with a pitch of 5 cm with an accuracy of 0.082 mm to form a 1.2-m-long LED tape. The luminance of the tape is 12.4 lx at a distance of 1 m, which is the luminance of outdoor corridor lighting. Therefore, this system can be used for meter-long tape lighting. 相似文献