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排序方式: 共有314条查询结果,搜索用时 15 毫秒
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DL Lacey JM Erdmann SL Teitelbaum HL Tan J Ohara A Shioi 《Canadian Metallurgical Quarterly》1995,136(6):2367-2376
Interleukin 4 (IL-4) is an immune cytokine that inhibits bone resorption in mice and suppresses osteoclastic cell formation in vitro through an undefined mechanism. In this report, we have established the cellular identity of the IL-4 target cell using a variety of bone marrow/stromal cell coculture methods. Initially, we found that the majority of IL-4's inhibition of osteoclastic cell formation was due to its effect on bone marrow cells, not stromal cells. Consequently, bone marrow macrophages were used as osteoclastic cell progenitors after they had been transiently exposed to IL-4 (48 h), before the addition of stromal cells, 1,25-dihydroxyvitamin D3, and dexamethasone. In this circumstance, IL-4 impaired subsequent osteoclastic cell formation, suggesting that the macrophage may be potentially targeted by many factors known to influence osteoclast formation. Consequently, we discovered that interferon-gamma (IFN gamma), prostaglandin E (PGE), and cell-permeant cAMP analogs also impacted osteoclastic cell formation when used to selectively treat bone marrow macrophages. IFN gamma suppressed osteoclastic cell formation, whereas PGE and cAMP analog treatment led to the formation of significantly enlarged osteoclastic cells. Importantly, PGE antagonized the inhibitory effects of both IL-4 and IFN gamma on the osteoclastic cell-forming potential of bone marrow macrophages. Collectively, these findings establish bone marrow macrophages as osteoclastic cell precursors with the degree of their commitment to the osteoclast pathway sensitive to the effects of soluble mediators, including IL-4, IFN gamma, and PGE. 相似文献
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Proteins are targeted to the membrane and matrix of peroxisomes by distinct pathways. Recent observations suggest a further route: a subset of peroxisomal membrane proteins might be targeted first to the endoplasmic reticulum, and from there to peroxisomes by vesicle-mediated transport. 相似文献
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The thermal curing reaction of two phenolic resole resins is monitored using the fluorescence technique. The intrinsic fluorescence can be used as an indicator for cure monitoring for the first resole. As the thermal curing proceeds, the intrinsic fluorescence intensity of the resole resin decreases and exhibits a few nanometers of redshift. The fluorescence intensity of the emission maxima is correlated with the conversion measured by differential scanning spectroscopy. A linear correlation is found at three different temperatures. The intrinsic fluorescence cannot always be used for monitoring the curing process of phenolic resole resins. Thus, three intramolecular charge transfer compounds and two organic donor–π‐acceptor salts are selected and applied for the cure monitoring of the second phenolic resole resin. As the curing reaction proceeds, the fluorescence emission spectra of the probes exhibit a blue spectral shift and the intensity changes because of environmental changes. An intensity ratio method is applied in which the ratios of the low‐ to high‐intensity changes in the emission bands are used to determine the degree of the curing process. There is a smooth correlation between the intensity ratio method and the degree of cure. The method enables one to follow the changes in the polymer structure at low and intermediate degrees of the curing process (below 70%) and obtain comparable results from different types of probes during the same curing process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1773–1780, 2002 相似文献
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High Conductivity in Molecularly p‐Doped Diketopyrrolopyrrole‐Based Polymer: The Impact of a High Dopant Strength and Good Structural Order
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Yevhen Karpov Tim Erdmann Ivan Raguzin Mahmoud Al‐Hussein Marcus Binner Uwe Lappan Manfred Stamm Kirill L. Gerasimov Tetyana Beryozkina Vasiliy Bakulev Denis V. Anokhin Dimitri A. Ivanov Florian Günther Sibylle Gemming Gotthard Seifert Brigitte Voit Riccardo Di Pietro Anton Kiriy 《Advanced materials (Deerfield Beach, Fla.)》2016,28(28):6003-6010
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JM Warnecke JP Fürste WD Hardt VA Erdmann RK Hartmann 《Canadian Metallurgical Quarterly》1996,93(17):8924-8928
To study the cleavage mechanism of bacterial Nase P RNA, we have synthesized precursor tRNA substrates carrying a single Rp- or Sp-phosphorothioate modification at the RNase P cleavage site. Both the Sp- and the Rp-diastereomer reduced the rate of processing by Escherichia coli RNase P RNA at least 1000-fold under conditions where the chemical step is rate-limiting. The Rp-modification had no effect and the Sp-modification had a moderate effect on precursor tRNA ground state binding to RNase P RNA. Processing of the Rp-diastereomeric substrate was largely restored in the presence of the "thiophilic" Cd2+ as the only divalent metal ion, demonstrating direct metal ion coordination to the (pro)-Rp substituent at the cleavage site and arguing against a specific role for Mg(2+)-ions at the pro-Sp oxygen. For the Rp-diastereomeric substrate, Hill plot analysis revealed a cooperative dependence upon [Cd2+] of nH = 1.8, consistent with a two-metal ion mechanism. In the presence of the Sp-modification, neither Mn2+ nor Cd2+ was able to restore detectable cleavage at the canonical site. Instead, the ribozyme promotes cleavage at the neighboring unmodified phosphodiester with low efficiency. Dramatic inhibition of the chemical step by both the Rp- and Sp-phosphorothioate modification is unprecedented among known ribozymes and points to unique features of transition state geometry in the RNase P RNA-catalyzed reaction. 相似文献
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Kati Raju Seyoung Kim Eun Jung Kang Kyong Sik Yun Young-Hoon Seong In-Sub Han Hyun-Kwuon Lee Ji Haeng Yu 《Journal of the European Ceramic Society》2021,41(9):4884-4895
The present work involved the application of a two-step sintering (TSS) technique for typical Ce0.9Gd0.1O2?δ–La0.6Sr0.4Co0.2Fe0.8O3–δ (GDC–LSCF) composites and its effect on the microstructure and resultantly mechanical and O2-permeating properties. The samples obtained by conventional sintering (CS) performed at 1100, 1250, and 1400 °C for 3 h exhibited maximum flexural strength and hardness values of 142 MPa and 8.71 GPa, respectively. However, the application of a TSS procedure produced fine-grained microstructures with improved mechanical properties. In particular, with the use of a typical 1250/1200 TSS protocol, increases of approximately 31 % and 7% in the flexural strength and hardness values, respectively, were observed compared to those obtained using the CS method. Moreover, thick-film (~ 60 μm) GDC–LSCF membrane prepared by tape casting and the TSS technique showed remarkably 1.5–2 times higher oxygen permeation flux than membrane sintered by CS method. The results are discussed and explained in detail. 相似文献
10.
Kati Raju Dang-Hyok Yoon Jai-Yeoul Lee 《Journal of Superconductivity and Novel Magnetism》2014,27(11):2501-2506
The crystal structure and magnetic properties of a typical polycrystalline double-layered manganite, La1.2Sr0.9Ca0.9Mn2O7, were examined using neutron diffraction and magnetization techniques. Neutron diffraction was performed at low and room temperatures and the crystal structure was refined using the Rietveld method based on the space group I4/Mmm. Low temperature neutron diffraction and magnetization measurements clearly revealed antiferromagnetic ordering. A neel transition was observed at approximately 150 K. 相似文献