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排序方式: 共有4513条查询结果,搜索用时 15 毫秒
51.
Fukushi Shuetsu Okada Masato Kageyama Tsutomu Hoshino Fuminori B. Katayama Kazuhiko 《Virus genes》1999,19(2):153-161
Translation initiation of hepatitis C virus (HCV) RNA is controlled by an internal ribosome entry site (IRES) contained in 5 noncoding region (NCR) and in several nucleotides of the coding region. The ability of a 25-kilodalton cellular protein (p25) to bind the HCV 5 NCR is correlated with the efficiency of translation initiation of HCV RNA, indicating that this protein plays a critical role in HCV translation (S. Fukushi, C. Kurihara, N. Ishiyama, F. B. Hoshino, A. Oya, and K. Katayama, J Virol 71, 1662–1666, 1997). We have extended the study for identification of the IRES region required for p25 binding. For this purpose, we have performed UV cross-linking competition analyses using 5- or 3- deleted mutants of the HCV 5 NCR as competitor RNAs for binding of p25 to wild-type HCV 5 NCR. Competitor RNAs lacking nucleotides (nt) 47–74 or nt 279–331 did not inhibit p25 binding to the HCV IRES, indicating that these regions are necessary for interaction of the p25 and HCV IRES. Since p25 binding was not observed in the IRES elements of encephalomyocarditis virus and poliovirus in UV cross-linking competition analyses, the p25 binding may be specific for the HCV IRES. p25 bound to the HCV IRES was detected when a purified 40S ribosomal subunit was used for UV cross-linking experiment, indicating that p25 is one of 40S ribosomal subunit proteins. These results reveal an unique interaction between the 40S ribosomal subunit and HCV IRES to contribute to translation initiation of the HCV genome. 相似文献
52.
Capillary endothelial proliferation is often a prominent feature of malignant gliomas. The understanding of structural and functional characteristics of the vascular microenvironment in gliomas is essential for the design of future therapeutic strategies against this tumor. Electron microscopic analysis of the capillary endothelial proliferation in malignant gliomas indicated that the complex vascular structures within the tumor were composed essentially of immature capillaries. Immature capillaries had a narrow slitlike lumen composed of endothelial cells with their high nuclear:cytoplasmic ratio and the relative paucity of organelles. They resembled capillary buds seen in normal repair tissue. Immature microvessels caused by angiogenesis were found more frequently in marginal zone of the tumors with increased microvessels. The tubular body was an organelle observed in vascular endothelial cells and was used frequently as a marker of the endothelial cell. Tubular bodies were evaluated by quantitative measurement of the mean percent (%) ratio of the number of endothelial cells with tubular bodies to all endothelial cells in microvessels of tumors. In glioblastomas it yielded a value of 32.4% in the margin, about two times as high as that in the center of the tumors. However, it was lower in all locations of astrocytomas. Tubular bodies in endothelial cells could be increased in proportion to neovascularization, and they might serve as a marker for increasing microvessels in astrocytic tumors. Tumor angiogenesis may be regulated by growth factors with angiogenic activities that are secreted by tumor cells. Vascular endothelial growth factor (VEGF) may play a critical role in the regulation of vascular endothelial proliferation. We found that 86% of 29 glioblastomas and 79% of 14 anaplastic astrocytomas demonstrated immunoreactivity for VEGF in their tumor cells. There tended to be a correlation between VEGF and vascularity. A correlation existed between the grade of immunoreactivity for VEGF and the grade of p53 protein expression in the malignant gliomas. However, the MIB-1 indices did not increase in correlation with increase in the extent of immunoreactivity for VEGF. 相似文献
53.
Cross-linking of Fc(gamma)-receptor on monocytes inhibits hepatitis C virus-specific cytotoxic T-lymphocyte induction in vitro. 总被引:2,自引:0,他引:2
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T Kanto N Hayashi T Takehara K Katayama A Ito K Mochizuki N Kuzushita T Tatsumi Y Sasaki A Kasahara M Hori 《Immunology》1998,94(4):461-468
In hepatitis C virus (HCV) infection, immune complex (IC)-type virus particles are frequently observed in circulation. The IC leads to cross-linking of Fcgamma receptors (FcgammaR) on monocytes and exerts immunoinhibitory function. To test the roles of IC in HCV-specific cytotoxic T lymphocyte (CTL) induction, we generated HCV CTL from peripheral blood mononuclear cells of chronic hepatitis C patients with or without HCV-IC- or immunoglobulin G (IgG)-coated culture plates and compared their lytic activities. HCV-IC or adherent IgG, which induces FcgammaR cross-linking, significantly reduced CTL activity. Expression of B7-1 on monocytes decreased on adherent IgG. In addition, tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) production increased from cells on adherent IgG and their mRNA expression in monocytes was enhanced. Anti-TNF-alpha antibody during induction on adherent IgG inhibited lysis; however, anti-TGF-beta completely reversed its inhibitory effect. These results demonstrated that HCV-IC or adherent IgG impaired HCV-CTL induction in vitro. The FcgammaR-mediated CTL suppression occurred via decreased expression of monocyte B7-1 and/or enhanced production of TGF-beta1. 相似文献
54.
Electrical polarization of plasma-spray-hydroxyapatite coatings for improvement of osteoconduction of implants 总被引:1,自引:0,他引:1
Kato R Nakamura S Katayama K Yamashita K 《Journal of biomedical materials research. Part A》2005,74(4):652-658
We have established the electrical polarization method of hydroxyapatite (HA) coatings (HAC) for clinical use, such as dental and orthopedic implants. The HAC examined in the current study was prepared in titanium substrates by plasma spraying of beta-tricalcium phosphate (TCP) powders followed by hydrothermal treatment. The prepared HAC consisted of a single phase of HA, because the starting TCP phase was completely transformed to the HA phase during the posthydrothermal treatment. Polarization was carried out at the elevated temperature of 400 degrees C under a d.c. field of 1 kV . cm(-1). The electrical measurements showed that the stored charges of the polarized HAC were greater than the reported value of the sintered ceramic HA. The enhanced bioactivity of the polarized HAC was demonstrated using 1.5 simulated body fluid (SBF). The crystal growth from the SBF solution was accelerated on the negatively charged surface in comparison with the untreated HAC. Similar to the polarized ceramic HA, the current results confirmed that the bioactivity of HAC would be effective for improving the initial fixation by polarization. 相似文献
55.
56.
Yasuhiro Amemiya Masamichi Katayama Susumu Harada 《Macromolecular chemistry and physics.》1977,178(9):2499-2505
Copolymers from 1,6-heptadiene ( 1 ) and SO2 with various mole ratios of their units were prepared. Their structures were studied by elemental analyses, IR and 1H NMR spectroscopy. Structures containing a cyclopentane ring ( 2 ) and such containing a thiane ring ( 3 ) in the main chain are proposed. 相似文献
57.
Cross education of muscular strength during unilateral resistance training and detraining 总被引:2,自引:0,他引:2
Shima N Ishida K Katayama K Morotome Y Sato Y Miyamura M 《European journal of applied physiology》2002,86(4):287-294
Abstract. The purpose of the present study was to examine the changes in maximum voluntary isometric contraction (MVC) in the contralateral
untrained limb during unilateral resistance training and detraining, and to examine the factors inducing these changes by
means of electrophysiological techniques. Nine healthy males trained their plantar flexor muscles unilaterally 4 days·week–1 for 6 weeks using 3 sets of 10–12 repetitions at 70–75% of one-repetition maximum a day, and detrained for 6 weeks. Progressive
unilateral resistance training significantly (P<0.05) increased MVC, integrated electromyogram (iEMG), and voluntary activation in the trained and contralateral untrained
limbs. The changes in MVC after training were significantly correlated with the changes in iEMG in both limbs. No significant
changes occurred in MVC, voluntary activation, and iEMG in the contralateral limb after detraining. The changes in MVC after
detraining did not correlate with the changes in voluntary activation or iEMG in either limb. Training and detraining did
not alter twitch and tetanic peak torques in either limb. These results suggest that the mechanisms underlying cross education
of muscular strength may be explained by central neural factors during training, but not solely so during detraining.
Electronic Publication 相似文献
58.
59.
Takada D Emi M Ezura Y Nobe Y Kawamura K Iino Y Katayama Y Xin Y Wu LL Larringa-Shum S Stephenson SH Hunt SC Hopkins PN 《Journal of human genetics》2002,47(12):0656-0664
60.
Kazuya Takeda Shuhei Sakakibara Kazuo Yamashita Daisuke Motooka Shota Nakamura Marwa Ali El Hussien Jun Katayama Yohei Maeda Masanobu Nakata Shigeyuki Hamada Daron M. Standley Masaki Hayama Takashi Shikina Hidenori Inohara Hitoshi Kikutani 《The Journal of allergy and clinical immunology》2019,143(3):1163-1175.e15