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81.
T Murakami M Yamamoto K Ono M Nishikawa N Nagata K Motoyoshi T Akatsu 《Canadian Metallurgical Quarterly》1998,252(3):747-752
Osteoclastogenesis inhibitory factor (OCIF), also termed osteoprotegerin (OPG), is a secreted member of the tumor necrosis factor (TNF) receptor family. It inhibits bone resorption in vivo and osteoclast-like cell (OCL) formation in vitro. To better understand the biological role of OCIF, we first examined the effects of various osteotropic agents on OCIF mRNA levels in mouse calvarial osteoblasts. Northern blot analysis showed that stimulators of OCL formation such as 1,25-(OH)2D3, prostaglandin E2 (PGE2), parathyroid hormone (PTH), and interleukin 1 (IL-1) decreased OCIF mRNA levels. In contrast, transforming growth factor (TGF)-beta1 increased OCIF mRNA levels in primary osteoblasts as well as in osteoblastic/stromal cell lines. Since it was reported that both TGF-beta1 and OCIF not only inhibited OCL formation but also impaired the survival of OCL by inducing apoptosis in vitro, we next examined the possible involvement of OCIF in TGF-beta1-induced impairment of OCL survival. In a mouse bone marrow culture, we confirmed that addition of OCIF or TGF-beta1 decreased the number of surviving OCL. Anti-OCIF IgG, which completely neutralized the effect of OCIF, partially prevented the TGF-beta1-induced decrease in the number of OCL. Our results suggest that (i) downregulation of OCIF expression is one of the mechanisms for the stimulatory effects of 1,25(OH)2D3, PGE2, PTH, and IL-1 on osteoclastogenesis; and (ii) the TGF-beta1-induced apoptosis of OCL is mediated, at least in part, by upregulation of OCIF expression. 相似文献
82.
We have generated mice having a single copy of the human haptoglobin gene (Hp2), driven by its natural promoter, and a neomycin resistance gene (Neo), driven by a herpes simplex thymidine kinase promoter with polyoma enhancers, inserted into two defined chromosomal locations, the Hprt locus on the X-chromosome and the apolipoprotein (apo) AI-CIII gene cluster on chromosome 9. The haptoglobin promoter is highly specialized in its tissue of action; the viral promoter has few restrictions. The apoAI-CIII gene is naturally active in only two tissues, whereas the Hprt gene region is ubiquitously active. Expression of both transgenes at substantial levels was achieved only (a) when the transgenes were inserted into the genome close to a known tissue-specific enhancer/locus control region in the apoAI-CIII gene cluster, and (b) when known conditions for function of their promoters were met. The specificities of the two chromosomal regions and of the two promoters are preserved, but their interactions are not specific. We conclude that transgenes are affected by locus-related enhancers in the same manner as nearby endogenous genes. Our experiments reinforce the usefulness of using gene targeting to direct single-copy transgenes to appropriate chromosomal locations. 相似文献
83.
T Clackson W Yang LW Rozamus M Hatada JF Amara CT Rollins LF Stevenson SR Magari SA Wood NL Courage X Lu F Cerasoli M Gilman DA Holt 《Canadian Metallurgical Quarterly》1998,95(18):10437-10442
FKBP ligand homodimers can be used to activate signaling events inside cells and animals that have been engineered to express fusions between appropriate signaling domains and FKBP. However, use of these dimerizers in vivo is potentially limited by ligand binding to endogenous FKBP. We have designed ligands that bind specifically to a mutated FKBP over the wild-type protein by remodeling an FKBP-ligand interface to introduce a specificity binding pocket. A compound bearing an ethyl substituent in place of a carbonyl group exhibited sub-nanomolar affinity and 1,000-fold selectivity for a mutant FKBP with a compensating truncation of a phenylalanine residue. Structural and functional analysis of the new pocket showed that recognition is surprisingly relaxed, with the modified ligand only partially filling the engineered cavity. We incorporated the specificity pocket into a fusion protein containing FKBP and the intracellular domain of the Fas receptor. Cells expressing this modified chimeric protein potently underwent apoptosis in response to AP1903, a homodimer of the modified ligand, both in culture and when implanted into mice. Remodeled dimerizers such as AP1903 are ideal reagents for controlling the activities of cells that have been modified by gene therapy procedures, without interference from endogenous FKBP. 相似文献
84.
Takanori Ambo Motoyoshi Noike Hirofumi Kurokawa Tanetoshi Koyama 《Journal of Bioscience and Bioengineering》2009,107(6):620-622
cis-Prenyltransferase catalyzes the synthesis of Z,E-mixed prenyl diphosphates by a condensation of isopentenyl diphosphate to an allylic diphosphate. A novel gene encoding a cis-prenyltransferase is cloned from Thermobifida fusca. It showed a unique substrate specificity accepting dimethylallyl diphosphate as a shortest allylic substrate, and synthesizes polyprenyl products up to C70. 相似文献
85.
A power control system for a doubly fed wound rotor induction generator has been developed. This power control system applies a control method using a rotating reference frame fixed on the gap flux of the generator, and can control active and reactive power independently and stably. The characteristics of the control system have been proved by experiment. Harmonic currents fed to the rotor windings are transmitted to the stator winding changing its frequency. The transmitting characteristics of the harmonic currents have been analyzed and verified by experiments 相似文献
86.
We have studied the enhancement of heat transfer by vortex generators. Experiments were performed on rectangular‐type vortex generators mounted on a parallel‐plate heater, and the heat transfer coefficient of the heater surface and pressure drop in the duct were measured. These measurements indicated that a rectangular vortex generator (called a double‐inclined winglet), with inclination angle of the vortex generator surface to the heater surface (β) at 60°, and the attack angle to the flow direction (γ) at 45°, maximizes the local Nusselt number of the heater surface. It was also found that a group of double‐inclined winglets has an optimal arrangement in a winglet array, longitudinal pitch and transverse pitch, that maximizes the ratio [Colburn's dimensionless heat transfer coefficient JH]/[friction factor f]. The results of numerical calculations showed that the double‐inclined winglet was superior to the conventional rectangular vortex generator in heat transfer. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(3): 253–267, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10089 相似文献
87.
Konishi M Nagahama T Fukuoka T Morita T Imura T Kitamoto D Hatada Y 《Journal of Bioscience and Bioengineering》2011,111(6):702-705
We improved the culture conditions for a biosurfactant producing yeast, Pseudozyma hubeiensis SY62. We found that yeast extract greatly stimulates MEL production. Furthermore, we demonstrated a highly efficient production of MELs in the improved medium by fed-batch cultivation. The final concentration of MELs reached 129 ± 8.2g/l for one week. 相似文献
88.
89.
Ximu Chen Kazuaki Toyoura Naoyuki Hatada Tetsuya Uda 《Journal of the American Ceramic Society》2022,105(8):5448-5460
With the aim to elucidate the proton conduction mechanism in sodium tantalite with an orthorhombic perovskite structure, o-NaTaO3, proton sites and elementary processes of proton jumps in the crystal were explored using first-principles calculations. In this crystal, interoctahedral hopping plays a key role in the proton conduction, contrast to cubic perovskites where protons migrate over a long range only by rotation and intraoctahedral hopping. The interoctahedral hopping results from the tilting structure of TaO6 octahedra units, which accelerates the relatively fast proton migration along b- and c-axes compared to that along a-axis. This suggests that the low symmetry of the crystal structure can be beneficial to proton conduction in some cases, although the low symmetry is generally considered to make the potential barrier of long-range proton migration higher. Considering the trapping effect of Ti dopants as the change in the concentration of mobile protons, the calculated proton conductivity is in excellent agreement with the experimental one. 相似文献
90.
Yoshinobu Adachi Naoyuki Hatada Ken Hirota Masaki Kato Tetsuya Uda 《Journal of the American Ceramic Society》2019,102(12):7077-7088
Lanthanum nickelates with Ruddlesden-Popper structure (La2NiO4, La3Ni2O7, and La4Ni3O10) and perovskite structure (LaNiO3) have attracted considerable attention due to their potential applications such as solid oxide fuel cells. Currently, the ionic and electronic conduction properties of La3Ni2O7, La4Ni3O10, and LaNiO3 are not fully understood because it is quite difficult to prepare their dense bodies required for the characterization. The difficulty arises from their narrow thermodynamic stable temperature and oxygen partial pressure ranges. In this study, we successfully obtained dense bodies of single-phase La3Ni2O7, La4Ni3O10, and LaNiO3 via a post-sintering oxidation process. First, dense pellets composed of fine-grain precursors La2NiO4 and NiO (~0.5 μm) were prepared by nitrate freeze-drying technique and low-temperature sintering at 1150°C-1225°C. Then they were converted into almost single-phase La3Ni2O7, La4Ni3O10, and LaNiO3 by high-temperature oxidation. La3Ni2O7 and La4Ni3O10 were obtained under an oxygen partial pressure of 1 bar at 1275°C and 1200°C-1250°C, respectively, while LaNiO3 was obtained under of 392 bar at 1250°C using hot isostatic pressing. The relative densities of the pellets exceeded 90%. With regard to their phase stability, decomposition was not detected at 600°C-1100°C in air for at least 100 hour despite their thermodynamic instability. 相似文献