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Search Results: 1 - 10 of 75 matches for " Shimpei Iikuni "
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Development of Novel 123I-Labeled Pyridyl Benzofuran Derivatives for SPECT Imaging of β-Amyloid Plaques in Alzheimer’s Disease
Masahiro Ono, Yan Cheng, Hiroyuki Kimura, Hiroyuki Watanabe, Kenji Matsumura, Masashi Yoshimura, Shimpei Iikuni, Yoko Okamoto, Masafumi Ihara, Ryosuke Takahashi, Hideo Saji
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074104
Abstract: Imaging of β-amyloid (Aβ) plaques in the brain may facilitate the diagnosis of cerebral β-amyloidosis, risk prediction of Alzheimer’s disease (AD), and effectiveness of anti-amyloid therapies. The purpose of this study was to evaluate novel 123I-labeled pyridyl benzofuran derivatives as SPECT probes for Aβ imaging. The formation of a pyridyl benzofuran backbone was accomplished by Suzuki coupling. [123I/125I]-labeled pyridyl benzofuran derivatives were readily prepared by an iododestannylation reaction. In vitro Aβ binding assays were carried out using Aβ(1–42) aggregates and postmortem human brain sections. Biodistribution experiments were conducted in normal mice at 2, 10, 30, and 60 min postinjection. Aβ labeling in vivo was evaluated by small-animal SPECT/CT in Tg2576 transgenic mice injected with [123I]8. Ex vivo autoradiography of the brain sections was performed after SPECT/CT. Iodinated pyridyl benzofuran derivatives showed excellent affinity for Aβ(1–42) aggregates (2.4 to 10.3 nM) and intensely labeled Aβ plaques in autoradiographs of postmortem AD brain sections. In biodistribution experiments using normal mice, all these derivatives displayed high initial uptake (4.03–5.49% ID/g at 10 min). [125I]8 displayed the quickest clearance from the brain (1.30% ID/g at 60 min). SPECT/CT with [123I]8 revealed higher uptake of radioactivity in the Tg2576 mouse brain than the wild-type mouse brain. Ex vivo autoradiography showed in vivo binding of [123I]8 to Aβ plaques in the Tg2576 mouse brain. These combined results warrant further investigation of [123I]8 as a SPECT imaging agent for visualizing Aβ plaques in the AD brain.
A loop group method for Demoulin surfaces in the 3-dimensional real projective space
Shimpei Kobayashi
Mathematics , 2013,
Abstract: For a surface in the 3-dimensional real projective space, we define a Gauss map, which is a quadric in $\mathbb R^{4}$ and called the first-order Gauss map. It will be shown that the surface is a Demoulin surface if and only if the first-order Gauss map is conformal, and the surface is a projective minimal coincidence surface or a Demoulin surface if and only if the first-order Gauss map is harmonic. Moreover for a Demoulin surface, it will be shown that the first-order Gauss map can be obtained by the natural projection of the Lorentz primitive map into a 6-symmetric space. We also characterize Demoulin surfaces via a family of flat connections on the trivial bundle $\D \times \SL$ over a simply connected domain $\mathbb{D}$ in the Euclidean 2-plane.
Nonlinear d'Alembert formula for discrete pseudospherical surfaces
Shimpei Kobayashi
Mathematics , 2015,
Abstract: On the basis of loop group decompositions (Birkhoff decompositions), we give a discrete version of the nonlinear d'Alembert formula, a method of separation of variables of difference equations, for discrete constant negative Gauss curvature (pseudospherical) surfaces in Euclidean three space. We also compute two examples by this formula in detail.
Real forms of complex surfaces of constant mean curvature
Shimpei Kobayashi
Mathematics , 2012,
Abstract: It is known that complex constant mean curvature ({\sc CMC} for short) immersions in $\mathbb C^3$ are natural complexifications of {\sc CMC}-immersions in $\mathbb R^3$. In this paper, conversely we consider {\it real form surfaces} of a complex {\sc CMC}-immersion, which are defined from real forms of the twisted $\mathfrak{sl}(2, \mathbb C)$ loop algebra $\Lambda \mathfrak{sl}(2, \mathbb C)_\sigma$, and classify all such surfaces according to the classification of real forms of $\Lambda \mathfrak{sl}(2, \mathbb C)_\sigma$. There are seven classes of surfaces, which are called {\it integrable surfaces}, and all integrable surfaces will be characterized by the (Lorentz) harmonicities of their Gau{\ss} maps into the symmetric spaces $S^2$, $H^2$, $S^{1,1}$ or the 4-symmetric space $SL(2, \mathbb C)/U(1)$. We also give a unification to all integrable surfaces via the generalized Weierstra{\ss} type representation.
TGF-beta1 on osteoimmunology and the bone component cells
Shimpei Kasagi, Wanjun Chen
Cell & Bioscience , 2013, DOI: 10.1186/2045-3701-3-4
Abstract: Bone is a rigid organ that constitutes part of the endoskeleton of vertebrates. It serves multiple functions; providing mechanical support for joints and tendons, protecting soft tissue or various organs from mechanical stress or trauma, storing minerals, generating hematopoietic cells, and producing hormones. These many functions are regulated by several soluble factors. Interestingly, accumulated evidence indicates that transforming growth factor beta 1 (TGF-β1) plays a critical role in bone formation, mineral storage, and hematopoietic cell generation. In addition, recent progress in the study of the cross-talk between the skeletal system and the immune system (termed osteoimmunology) has revealed shared components and mechanisms between the two systems [1]. This review highlights recent findings focusing on the role of TGF-β1 in bone metabolism and osteoimmunology.TGF-β1 is a one of the most potent regulatory cytokines with diverse effects on hematopoietic cells. In the immune system, TGF-β1 induces and maintains immune tolerance by regulation of lymphocyte proliferation, differentiation, and survival. Disruption of TGF-β1 results in a dysregulated immune system [2], leading to inappropriate immune cell activation, inflammation, cancer (Leukemia and malignant lymphoma etc) and autoimmune diseases [3]. In fact, TGF-β1-deficient mice (TGF-β1ko) die within 2-3 weeks after birth due to lymphocyte and monocyte infiltration of multiple vital organs [3,4]. CD4+Foxp3+ T cells that predominantly produce anti-inflammatory cytokines (TGF-β, IL-10), but not inflammatory cytokines (IFN-γ, TNF-α, and IL-17) are known as regulatory T cells (Tregs). They inhibit the action of other effector T cells through soluble factors (TGF-β or IL-10) or cell-to-cell contact [5]. It is well known that TGF-β suppresses inflammatory cytokine production by effector T cells, and additionally, it drives the differentiation of na?ve T cells to CD4+CD25+Foxp3+ Tregs [6]. Moreover, TGF-β controls t
Cadmium transport and tolerance in rice: perspectives for reducing grain cadmium accumulation
Shimpei Uraguchi, Toru Fujiwara
Rice , 2012, DOI: 10.1186/1939-8433-5-5
Abstract: Cadmium (Cd) is a toxic heavy metal and is also known as one of the major environmental pollutants. Moderate Cd contamination of arable soils can result in considerable Cd accumulation in edible parts of crops (Arao and Ae 2003; Arao et al. 2003; Wolnik et al. 1983). Such levels of Cd in plants are not toxic to crops but can contribute to substantial Cd dietary intake by humans (Wagner 1993). In the case of "Itai-itai disease", Cd-polluted rice was the major source of Cd intake in the patients (Yamagata and Shigematsu 1970). This is the early case of chronic Cd toxicity in general populations without specific industrial exposure. Even in recent general populations in Japan, the internal Cd level is higher than those of other countries and this is largely because of daily consumption of Japanese rice which contains relatively high Cd (Watanabe et al., 1996; Watanabe et al. 2000; Tsukahara et al. 2003). Cd concentrations of recent Japanese rice have been constantly higher compared to those of other countries (Watanabe et al., 1996; Shimbo et al., 2001), although the values are much lower than the limit established by the Codex Alimentarius Commission of FAO/WHO (0.4 mg/kg). In some areas in China and Thailand, production of highly Cd-polluted rice and renal disfunctions among populations were reported (Nordberg et al., 1997; Jin et al., 2002; Honda et al., 2010). In the United States, increased consumption of rice and other cereals contributes to the recent increase of the dietary Cd intake (Egan et al. 2007). Many reports suggest importance to consider chronic effects of Cd exposure through foods (Jarup and Akesson 2009). In Japanese populations, the average dietary Cd intake (3.0 μg Cd/kg body weight/week) exceeds the tolerable weekly intake (2.5 μg Cd/kg body weight) set by the European Food Safety Authority (EFSA) and is about 50% of a provisional tolerable monthly intake (25 μg Cd/kg body weight/month) established by the Joint Food and Agriculture Organization/Wo
Development of Micro-Blog Based Discussion Environment for Participants in University Lecture
Shimpei Matsumoto,Tomoko Kashima
Lecture Notes in Engineering and Computer Science , 2012,
Hijacking of the Host SCF Ubiquitin Ligase Machinery by Plant Pathogens
Shimpei Magori,Vitaly Citovsky
Frontiers in Plant Science , 2011, DOI: 10.3389/fpls.2011.00087
Abstract: The SCF (SKP1-CUL1-F-box protein) ubiquitin ligase complex mediates polyubiquitination of proteins targeted for degradation, thereby controlling a plethora of biological processes in eukaryotic cells. Although this ubiquitination machinery is found and functional only in eukaryotes, many non-eukaryotic pathogens also encode F-box proteins, the critical subunits of the SCF complex. Increasing evidence indicates that such non-eukaryotic F-box proteins play an essential role in subverting or exploiting the host ubiquitin/proteasome system for efficient pathogen infection. A recent bioinformatic analysis has identified more than 70 F-box proteins in 22 different bacterial species, suggesting that use of pathogen-encoded F-box effectors in the host cell may be a widespread infection strategy. In this review, we focus on plant pathogen-encoded F-box effectors, such as VirF of Agrobacterium tumefaciens, GALAs of Ralstonia solanacearum, and P0 of Poleroviruses, and discuss the molecular mechanism by which plant pathogens use these factors to manipulate the host cell for their own benefit.
Strategy for early SUSY searches at ATLAS
Shimpei Yamamoto,for the ATLAS collaboration
Physics , 2007,
Abstract: The CERN Large Hadron Collider (LHC) is scheduled to commence operation in 2008 and inclusive searches for supersymmetry (SUSY) will be one of our primary tasks in the first days of LHC operation. It is certain that the final state of multijets + missing transverse energy will provide a superior performance in SUSY searches. Strategies to understand the instrumental background and to understand the Standard Model (SM) background are still under development and are urgent issues for the coming data. We describe the strategy for early SUSY searches at the ATLAS experiment using the fist data corresponding to an integrated luminosity up to 1fb^-1, which comprises much progress in the data-driven technique for the SM background estimations.
Perfect screening of the inter-polaronic interaction
Shimpei Endo,Masahito Ueda
Physics , 2013,
Abstract: We consider heavy particles immersed in a Fermi sea of light fermions, and study the interaction between the heavy particles induced by the surrounding light fermions. With the Born-Oppenheimer method, we analytically show that the induced interaction between N heavy particles vanishes for any N in the limit of high light-fermion density. The induced interaction vanishes even in the unitarity regime. This suggests that the formation of N-body bound states associated with the Efimov effect is suppressed in the presence of the dense Fermi sea. We ascribe the vanishing induced interaction to the screening effect in the neutral Fermi system.
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