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91.
Distribution and Dynamic Pathway of Selenium Species in Selenium-deficient Mice Injected with (82)Se-enriched Selenite 总被引:1,自引:0,他引:1
Kaori Shigeta Kentaro Matsumura Yoshinari Suzuki Atsuko Shinohara Naoki Furuta 《Analytical sciences》2008,24(9):1117-1122
In order to elucidate Se metabolism in a living body, (82)Se-enriched selenite was injected intravenously into mice fed Se-adequate and -deficient diets. We studied the time-dependent changes in the distribution of the labeled Se in organs, red blood cells, and plasma. The total Se was determined by flow-injection ICPMS, and Se speciation analysis was conducted by micro-affinity chromatography coupled with low-flow ICPMS. Total Se in almost all organs, including liver, showed the maximum at 1 h after injection. From speciation analysis, exogenous (82)Se as Se-containing proteins other than selenoprotein P (Sel-P) (selenium containing albumin (SeAlb) and extra cellular glutathione peroxidase (eGPx)), peaked at 1 h and quickly decreased from 1 to 6 h after injection, whereas that as Sel-P, peaked at 6 h, and gradually decreased from 6 to 72 h after injection. We found that there were two pathways for the transfer of Se in mice; one was as SeAlb until 1 h after injection, and the other was as Sel-P from 6 to 72 h after injection. 相似文献
92.
Otsuki J Kanazawa Y Kaito A Shafiqul Islam DM Araki Y Ito O 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(12):3776-3784
Excited energy-transfer processes were investigated for a supramolecular Zn-porphyrin free-base porphyrin dyad, ZnPA-2 x FbPC-2, in which beta-octaalkylated meso-diarylporphyrins are connected through an amidinium-carboxylate salt bridge. The rate of energy transfer in the dyad (1.3 x 10(9) s(-1)) is substantially slower than that in the previously reported dyad, ZnPA-1FbPC-1 (4.0 x 10(9) s(-1)), in which meso-tetraarylporphyrins are connected through the same amidinium-carboxylate salt bridge. The F?rster-type mechanism can explain only minor parts of these rates (3.3 x 10(8) and 5.1 x 10(8) s(-1), respectively). Thus, Dexter-type through-bond energy transfer may be invoked. Indeed, bridge-mediated electronic processes would be favored in ZnPA-1 x FbPC-1 over ZnPA-2 x FbPC-2 on the basis of steric and electronic factors. Sterically, the phenyl groups in ZnPA-2 and FbPC-2 are more closely perpendicular to the porphyrin planes than those in ZnPA-1 and FbPC-1. Electronically, the energy and symmetry of the occupied frontier orbitals should favor ZnPA-1 x FbPC-1 over ZnPA-2 x FbPC-2 in terms of electronic interactions through the bridge. Therefore, the observed trend (ZnPA-1 x FbPC-1>ZnPA-2 x FbPC-2), consistent with these considerations, lends further support to the through-bond mechanism. Thus, the amidinium-carboxylate salt bridge is effective in mediating through-bond energy transfer even though the bond is noncovalent. 相似文献
93.
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95.
Taniguchi Y Ikehara T Kamo N Watanabe Y Yamasaki H Toyoshima Y 《Photochemistry and photobiology》2007,83(2):311-316
The photoreceptor phoborhodopsin (ppR; also called sensory rhodopsin II) forms a complex with its cognate the Halobacterial transducer II (pHtrII) in the membrane, through which changes in the environmental light conditions are transmitted to the cytoplasm in Natronomonas pharaonis to evoke negative phototaxis. We have applied a fluorescence resonance energy transfer (FRET)-based method for investigation of the light-induced conformational changes of the ppR/pHtrII complex. Several far-red dyes were examined as possible fluorescence donors or acceptors because of the absence of the spectral overlap of these dyes with all the photointermediates of ppR. The flash-induced changes of distances between the donor and an acceptor linked to cysteine residues which were genetically introduced at given positions in pHtrII(1-159) and ppR were determined from FRET efficiency changes. The dye-labeled complex was studied as solubilized in 0.1% n-dodecyl-beta-D-maltoside (DDM). The FRET-derived changes in distances from V78 and A79 in pHtrII to V185 in ppR were consistent with the crystal structure data (Moukhametzianov, R. et al. [2006] Nature, 440, 115-119). The distance from D102 in pHtrII linker region to V185 in ppR increased by 0.33 angstroms upon the flash excitation. These changes arose within 70 ms (the dead time of instrument) and decayed with a rate of 1.1 +/- 0.2 s. Thus, sub-angstrom-scale distance changes in the ppR/pHtrII complex were detected with this FRET-based method using far-red fluorescent dyes; this method should be a valuable tool to investigate conformation changes in the transducer, in particular its dynamics. 相似文献
96.
Park JS Akiyama Y Yamasaki Y Kataoka K 《Langmuir : the ACS journal of surfaces and colloids》2007,23(1):138-146
Novel thermosensitive polyion complex (PIC) micelles were prepared in an aqueous medium based on the complexation of a pair of oppositely charged block ionomers, poly(2-isopropyl-2-oxazoline)-b-poly(amino acid)s (PiPrOx-b-PAA), containing thermosensitive PiPrOx segments. The controlled synthesis of PiPrOx-b-PAA was achieved via the ring-opening anionic polymerization of N-carboxyanhydrides (NCA) of either eta-benzyloxycarbonyl-l-lysine (Lys(Z)-NCA) or beta-benzyl-l-aspartate (BLA-NCA) with omega-amino-functionalized PiPrOx macroinitiators and the subsequent deprotection reaction under acidic or basic conditions. Gel permeation chromatography (GPC) and 1H NMR spectroscopy revealed that the syntheses of two block ionomers, poly(2-isopropyl-2-oxazoline)-b-poly(l-lysine) [PiPrOx-P(Lys)] and poly(2-isopropyl-2-oxazoline)-b-poly(aspartic acid) [PiPrOx-P(Asp)], proceeded almost quantitatively to give samples with a narrow molecular weight distribution (Mw/Mn = 1.2). The mixing of these two oppositely charged block ionomers in an aqueous medium led to the spontaneous formation of PIC micelles, which was confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The PIC micelles were spherical particles with a narrow distribution in the range of the measured concentration (0.125-1 mg/mL) and were stable without any secondary aggregates. Furthermore, the PIC micelles had a constant cloud-point temperature (Tcp) of approximately 32 degrees C under physiological conditions regardless of the total concentration, suggesting that the concentration factor is almost negligible with respect to the Tcp of the micelles presumably because of the increased local concentration of the PiPrOx segments in the shell layer. These PIC micelles have a promising application as a size-regulated smart nanocontainer loading charged compounds as well as bearing a thermosensitive outer shell that is useful for physical affinity control. 相似文献
97.
Matsuura H Nomura S Subeki Yamada K Yamasaki M Yamato O Maede Y Katakura K Trimurningsih Chairul Yoshihara T Nabeta K 《Natural product research》2007,21(4):328-333
Anti-babesial ingredients, (12R)- and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols, were isolated from Curcuma xanthorrhiza. The structures were established by the extensive NMR techniques. The assignments of (1)H NMR data of (12R)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was revised, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was isolated as a pure form for the first time. The IC(50) of the active compounds were compared with that of commercial drug, diminazene aceturate (Ganaseg). IC(50) values of Ganaseg, (12R)-, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols were 0.6 microg mL(-1), 8.3 microg mL(-1) and 11.6 microg mL(-1), respectively. 相似文献
98.
Yoshiteru Akezaki Shunichi Yasuda Katumi Hamaoka Yoshinobu Yoshimoto Susumu Yoshimura Takuo Nomura Hiroshi Yamasaki Atushi Sato 《Physical Therapy Research》2009,12(1):9-12
Purpose: The obstacle negotiation gait (ONG) is a fundamental activity of daily living. In cerebrovascular hemiplegic patients (stroke patients), the weight-bearing rate (WBR) on the paretic limb necessary for an independent ONG was studied. Methods: One hundred and seventeen stroke patients were involved. The patients'' average age at the time of the study was 67 years, and the average time from stroke onset was 102 days. There were 68 men and 49 women. Seventy patients were right hemiplegics, and 47 were left hemiplegics. The correlations between ONG and age, sex, body mass index (BMI), time from stroke onset, muscle strength of both the paretic and non-paretic limbs, Brunnstrom stage of the lower limbs, deep sensation, and the WBR on both the paretic and non-paretic limbs were studied. Patients who could perform ONG independently and safely were categorized as the independent group (IG), and those who needed observation or any assistance were categorized as the dependent group (DG). Results: The BMI, muscle strength of both the paretic and non-paretic limbs, Brunnstrom stage of the lower limbs, deep sensation and the WBR for both the paretic and non-paretic limbs were significantly different between the IG and DG groups. In particular, the WBR on the paretic limb was found to correlate significantly with the ONG, and a WBR value of 80.5% on the paretic limb gave a clear cut-off value. Conclusion: Although multiple factors influenced the ONG of stroke patients, the WBR on the paretic limb was the most influential. 相似文献
99.
The Ni-catalyzed [3+2+2] cocyclization between ethyl cyclopropylideneacetate (1) and 1,3-diynes afforded cycloheptadiene derivatives. The three-component reaction of 1, 1,3-diynes, and alkynes proceeded with good yield and high selectivity. Scope of the substrates was studied, and the origin of chemo- and regioselectivity of the reaction is discussed. 相似文献
100.
Suzuko Yamazaki Hiroyuki Abe Toshifumi Tanimura Yousuke Yamasaki Kenji Kanaori Kunihiko Tajima 《Research on Chemical Intermediates》2009,35(1):91-101
The thermal treatment of TiO2 pellets prepared by the sol–gel method decreased the photocatalytic activity. The activity divided by the specific surface
area of the pellets for the complete mineralization of ethylene or chloroform was maximized at the firing temperature of 400°C.
For the photocatalytic degradation of trichloroethylene (TCE), most of them were converted to chlorinated by-products, such
as dichloroacetic acid, chloroform, and phosgene, and the stoichiometric ratio of [CO2]formed/[TCE]degraded showed a maximal value at 400°C. The electron spin resonance (ESR) spin-trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO)
in the flow injection system indicated that firing at 400°C gave the highest signal intensity of DMPO–OH adducts. These findings
indicated that the OH radical was produced most effectively on the TiO2 fired at 400°C, which would be related to the content of anatase and rutile. Concerning the formation of chlorinated by-products
from TCE, more dichloroacetic acid (DCAA) were detected and less CHCl3 and COCl2 were formed at lower firing temperatures, suggesting that the branching ratio of chloroethoxy radicals to the formation of
DCAA or CHCl3 and COCl2 by C–C bond scission depended on the firing temperature. 相似文献