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81.
Terauchi T Asai N Doko T Taguchi R Takenaka O Sakurai H Yonaga M Kimura T Kajiwara A Niidome T Kume T Akaike A Sugimoto H 《Bioorganic & medicinal chemistry》2007,15(22):7098-7107
We present efficient syntheses of serofendic acids A and B (SA-A and SA-B), novel neuroprotective substances isolated from fetal calf serum. Biological and pharmacological evaluation showed that SA-A and SA-B have potent protective action against glutamate-induced neurotoxicity, but do not interact directly with glutamate receptors. A pharmacokinetic study showed that they have good oral bioavailability in rats. The results indicate that SA-A and SA-B are potential lead compounds for candidate drugs to treat various neurological disorders. 相似文献
82.
Kawaguchi A Asano H Matsushima K Wada T Yoshida S Ichida S 《Neurochemical research》2007,32(9):1469-1475
It is well known that morphological and functional changes during neural differentiation sometimes accompany the expression
of various voltage-gated ion channels. In this work, we investigated whether the enhancement of sodium current in differentiated
neuroblastoma × glioma NG108-15 cells treated with dibutyryl cAMP is related to the expression of voltage-gated sodium channels.
The results were as follows. (1) Sodium current density on peak voltage in differentiated cells was significantly enhanced
compared with that in undifferentiated cells, as detected by the whole-cell patch clamp method. The steady-state inactivation
curve in differentiated cells was similar to that for undifferentiated cells, but a hyperpolarized shift in the activation
curve for differentiated cells was observed. The sodium currents of differentiated and undifferentiated cells were completely
inhibited by 10−7 M tetrodotoxin (TTX). (2) The only NaV mRNA with an increased expression level during neuronal differentiation was that for NaV1.7, as observed by real-time PCR analysis. (3) The increase in the level of NaV1.7 α subunit expression during neuronal differentiation was also observed by immunocytochemistry; in particular, the localization
of NaV1.7 α subunits on the soma, varicosities and growth cone was significant. These results suggest that the enhancement of TTX-sensitive
sodium current density in differentiated NG108-15 cells is mainly due to the increase in the expression of the TTX-sensitive
voltage-gated Na+ channel, NaV1.7. 相似文献
83.
84.
Background
The purpose of this study was to investigate the coordination strategy of maximal-effort horizontal jumping in comparison with vertical jumping, using the methodology of computer simulation. 相似文献85.
86.
87.
Takasu A Kondo S Ito A Furukawa Y Higuchi M Kinoshita T Kwon I 《Biomacromolecules》2011,12(10):3444-3452
In vivo incorporation of phenylalanine (Phe) analogues into an artificial extracellular matrix protein (aECM-CS5-ELF) was accomplished using a bacterial expression host that harbors the mutant phenylalanyl-tRNA synthetase (PheRS) with an enlarged binding pocket. Although the Ala294Gly/Thr251Gly mutant PheRS (PheRS**) under the control of T5 promoter allows incorporation of some Phe analogues into a protein, the T5 system is not suitable for material science studies because the amount of materials produced is not sufficient due to the moderate strength of the T5 promoter. This limitation can be overcome by using a pair of T7 promoter and T7 RNA polymerase instead. In the T7 expression system, it is difficult, however, to achieve a high incorporation level of Phe analogues, due to competition of Phe analogues for incorporation with the residual Phe that is required for synthesis of active T7 RNA polymerase. In this study, we prepared the PheRS** under T7 promoter and optimized culture condition to improve both the incorporation level of recombinant aECM protein and the incorporation level of Phe analogues. Incorporation and expression levels tend to increase in the case of p-azidophenylalanine, p-iodophenylalanine, and p-acetylphenylalanine. We evaluated the lower critical transition temperature, which is dependent on the incorporation ratio and the turbidity decreased when the incorporation level increased. Circular dichromism measurement indicated that this tendency is based on conformational change from random coil to β-turn structure. We demonstrated that polyethylene glycol (PEG) can be conjugated at reaction site of Phe analogues incorporated. We also demonstrated that the increased hydrophilicity of elastin-like sequences in the aECM-CS5-ELF made by PEG conjugation could suppress nonspecific adhesion of human umbilical vein endothelial cells (HUVEC). 相似文献
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89.
Hydroxylated polychlorinated biphenyls are the metabolites produced from parent compounds by the drug-metabolizing enzyme cytochrome P450. These compounds are suspected to disrupt postembryonic neural development in the brains of mammals including humans. We studied the effects of these compounds on thyroid hormone function in the brain by using metamorphosing tadpoles of the African clawed toad (Xenopus laevis) as a model for mammalian postembryonic development. The metamorphosis assay revealed that these compounds inhibit thyroid hormone-induced metamorphosis. Genome-wide gene expression analysis in the brain following short-term exposure demonstrated that delayed metamorphosis could partially be caused by disruption of thyroid hormone-induced gene expression. Furthermore, we associated the terms of functional ontology with the genes, whose expression was disrupted by these compounds. We suggest that the use of a genome-wide analysis coupled with bioinformatics might provide an overview of the molecular mechanism underlying thyroid-disrupting activities in vivo. 相似文献
90.
Individual feeding area specialization has been reported for several seabird species. Researchers suspect that this behaviour results in feeding and/or reproductive advantages. Adélie Penguins Pygoscelis adeliae feed in small predictable open waters in a fast sea-ice area near Syowa Station, Antarctica. Their feeding sites were determined by radiotracking both members of 20 pairs rearing chicks. Twenty-five birds repeatedly fed in distinct areas more frequently than expected by chance, while the remaining 15 birds had no significant feeding area specialization. Birds seemed to feed at sites that were closer to their most recent feeding sites than they were to earlier feeding sites. Variation in specialized area, degree of feeding area fidelity and distance to feeding sites had no significant effect on the number of feeds that a bird brought to chicks per day. Neither did the estimated mass of feeds brought per day per pair depend on feeding area specialization. 相似文献