472 results on '"Sada K"'
Search Results
202. DNA-assisted swarm control in a biomolecular motor system.
- Author
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Keya JJ, Suzuki R, Kabir AMR, Inoue D, Asanuma H, Sada K, Hess H, Kuzuya A, and Kakugo A
- Subjects
- Azo Compounds, Kinesins, Light, Nanostructures, Ultraviolet Rays, Biophysical Phenomena, Cytoskeleton, DNA, Microtubules, Motion
- Abstract
In nature, swarming behavior has evolved repeatedly among motile organisms because it confers a variety of beneficial emergent properties. These include improved information gathering, protection from predators, and resource utilization. Some organisms, e.g., locusts, switch between solitary and swarm behavior in response to external stimuli. Aspects of swarming behavior have been demonstrated for motile supramolecular systems composed of biomolecular motors and cytoskeletal filaments, where cross-linkers induce large scale organization. The capabilities of such supramolecular systems may be further extended if the swarming behavior can be programmed and controlled. Here, we demonstrate that the swarming of DNA-functionalized microtubules (MTs) propelled by surface-adhered kinesin motors can be programmed and reversibly regulated by DNA signals. Emergent swarm behavior, such as translational and circular motion, can be selected by tuning the MT stiffness. Photoresponsive DNA containing azobenzene groups enables switching between solitary and swarm behavior in response to stimulation with visible or ultraviolet light.
- Published
- 2018
- Full Text
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203. Lipophilic polyelectrolyte gel derived from phosphonium borate can absorb a wide range of organic solvents.
- Author
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Sunaga S, Kokado K, and Sada K
- Abstract
Herein, we demonstrate a polyelectrolyte gel which can absorb a wide range of organic solvents from dimethylsulfoxide (DMSO, permittivity: ε = 47.0) to tetrahydrofuran (ε = 5.6). The gel consists of polystyrene chains with small amounts (∼5 mol%) of lipophilic electrolytes derived from triphenylphosphonium tetraaryl borate. The swelling ability of the polyelectrolyte gel was higher than that of the alkyl ammonium tetraaryl borate previously reported by us, and this is attributed to the higher compatibility with organic solvents, as well as the higher dissociating ability, of the triphenyl phosphonium salt. The role of the ionic moieties was additionally confirmed by post modification of the polyelectrolyte gel via a conventional Wittig reaction, resulting in a nonionic gel. Our findings introduced here will lead to a clear-cut molecular design for polyelectrolyte gels which absorb all solvents.
- Published
- 2018
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204. Development of a multiplex real-time PCR assay for detection of human enteric viruses other than norovirus using samples collected from gastroenteritis patients in Fukui Prefecture, Japan.
- Author
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Kowada K, Takeuchi K, Hirano E, Toho M, and Sada K
- Subjects
- Adenoviridae genetics, Adenoviridae isolation & purification, Child, Child, Preschool, Coinfection epidemiology, Coinfection virology, Disease Outbreaks, Feces virology, Foodborne Diseases diagnosis, Foodborne Diseases epidemiology, Foodborne Diseases virology, Gastroenteritis diagnosis, Gastroenteritis epidemiology, Humans, Infant, Japan epidemiology, Norovirus genetics, RNA, Viral genetics, Rotavirus genetics, Rotavirus isolation & purification, Sapovirus genetics, Sapovirus isolation & purification, Viruses classification, Viruses genetics, Gastroenteritis virology, Multiplex Polymerase Chain Reaction methods, Norovirus isolation & purification, Real-Time Polymerase Chain Reaction methods, Viruses isolation & purification
- Abstract
There are many varieties of gastroenteritis viruses, of which norovirus (NoV) accounts for over 90% of the viral food poisoning incidents in Japan. However, protocols for rapidly identifying other gastroenteritis viruses need to be established to investigate NoV-negative cases intensively. In this study, a multiplex real-time PCR assay targeting rotavirus A, rotavirus C, sapovirus, astrovirus, adenovirus, and enterovirus was developed using stool samples collected from gastroenteritis patients between 2010 and 2013 in Fukui Prefecture, Japan. Of the 126 samples collected sporadically from pediatric patients with suspected infectious gastroenteritis, 51 were positive for non-NoV target viruses, whereas 27 were positive for NoV, showing a high prevalence of non-NoV viruses in pediatric patients. In contrast, testing in 382 samples of 58 gastroenteritis outbreaks showed that non-NoV viruses were detected in 13 samples, with NoV in 267. Of the 267 NoV-positive patients, only two were co-infected with non-NoV target viruses, suggesting that testing for non-NoV gastroenteritis viruses in NoV-positive samples was mostly unnecessary in outbreak investigations. Given these results, multiplex real-time PCR testing for non-NoV gastroenteritis viruses, conducted separately from NoV testing, may be helpful to deal with two types of epidemiological investigations, regular surveillance of infectious gastroenteritis and urgent testing when gastroenteritis outbreaks occur., (© 2017 Wiley Periodicals, Inc.)
- Published
- 2018
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205. A New Aspect of Cholinergic Transmission in the Central Nervous System
- Author
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Muramatsu I, Masuoka T, Uwada J, Yoshiki H, Yazama T, Lee KS, Sada K, Nishio M, Ishibashi T, Taniguchi T, Akaike A, Shimohama S, and Misu Y
- Abstract
In the central nervous system, acetylcholine (ACh) is an important neurotransmitter related to higher brain functions and some neurodegenerative diseases. It is released from cholinergic nerve terminals and acts on presynaptic and postsynaptic ACh receptors (AChRs). Following release, ACh is rapidly hydrolyzed and the resultant choline is recycled as a substrate for new ACh synthesis. However, this classical concept of cholinergic transmission is currently reevaluated due to new evidence. In the cholinergic synapse, ACh may be itself taken up into postsynaptic neurons by a specific transport system and may act on AChRs at intracellular organelles (Golgi apparatus and mitochondria). Choline for ACh synthesis in cholinergic nerve terminals may be mainly supplied from choline at relevant concentration levels present in the extracellular space, rather than recycled from ACh-derived choline. Recent evidence has reopened the issue of classical cholinergic transmission and cognition, and may provide a novel approach to rational drug development for the treatment of neurodegenerative disorders such as Alzheimer’s disease., (Copyright 2018, The Author(s).)
- Published
- 2018
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206. Tubulointerstitial Nephritis with IgM-Positive Plasma Cells.
- Author
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Takahashi N, Saeki T, Komatsuda A, Munemura C, Fukui T, Imai N, Homma N, Hatta T, Samejima KI, Fujimoto T, Omori H, Ito Y, Nishikawa Y, Kobayashi M, Morikawa Y, Fukushima S, Yokoi S, Mikami D, Kasuno K, Kimura H, Nemoto T, Nakamoto Y, Sada K, Sugai M, Naiki H, Yoshida H, Narita I, Saito Y, and Iwano M
- Subjects
- Adult, Aged, Female, Humans, Male, Middle Aged, Immunoglobulin M, Nephritis, Interstitial blood, Nephritis, Interstitial immunology, Plasma Cells immunology
- Abstract
Infiltration by IgG-positive plasma cells is a common finding in tubulointerstitial nephritis. Indeed, it has been thought that CD138-positive mature plasma cells secrete mainly IgG, and the occurrence of tubulointerstitial nephritis with CD138-positive plasma cells secreting IgM has rarely been reported. Routine immunofluorescence of fresh frozen sections is considered the gold standard for detection of immune deposits. However, the immunoenzyme method with formalin-fixed, paraffin-embedded sections is superior for detecting IgM- or IgG-positive cells within the renal interstitium, thus histologic variants may often go undetected. We recently discovered a case of tubulointerstitial nephritis showing IgM-positive plasma cell accumulation within the interstitium. To further explore the morphologic and clinical features of such cases, we performed a nationwide search for patients with biopsy-proven tubulointerstitial nephritis and high serum IgM levels. We identified 13 patients with tubulointerstitial nephritis and IgM-positive plasma cell infiltration confirmed with the immunoenzyme method. The clinical findings for these patients included a high prevalence of distal renal tubular acidosis (100%), Fanconi syndrome (92%), and anti-mitochondrial antibodies (82%). The pathologic findings were interstitial nephritis with diffusely distributed CD3-positive T lymphocytes and colocalized IgM-positive plasma cells, as well as tubulitis with CD3-positive T lymphocytes in the proximal tubules and collecting ducts. Additionally, levels of H
+ -ATPase, H+ , K+ -ATPase, and the HCO3 - -Cl- anion exchanger were markedly decreased in the collecting ducts. We propose to designate this group of cases, which have a common histologic and clinical form, as IgM-positive plasma cell-tubulointerstitial nephritis., (Copyright © 2017 by the American Society of Nephrology.)- Published
- 2017
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207. Low glucose induces mitochondrial reactive oxygen species via fatty acid oxidation in bovine aortic endothelial cells.
- Author
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Kajihara N, Kukidome D, Sada K, Motoshima H, Furukawa N, Matsumura T, Nishikawa T, and Araki E
- Subjects
- Animals, Aorta, Cattle, Endothelial Cells metabolism, Endothelial Cells physiology, Hypoglycemia metabolism, Hypoglycemia physiopathology, Metabolomics, Nitric Oxide Synthase metabolism, Oxidation-Reduction, Oxygen Consumption, Vascular Cell Adhesion Molecule-1 metabolism, Fatty Acids metabolism, Glucose metabolism, Mitochondria metabolism, Reactive Oxygen Species metabolism
- Abstract
Aims/introduction: Overproduction of reactive oxygen species (ROS) in endothelial cells (ECs) plays a pivotal role in endothelial dysfunction. Mitochondrial ROS (mtROS) is one of the key players in the pathogenesis of diabetic vascular complications. Hypoglycemia is linked to increased ROS production and vascular events; however, the underlying mechanisms remain unclear. In the present study, we aimed to determine whether and how low glucose (LG) mediates mtROS generation in ECs, and to examine the impact of LG-induced mtROS on endothelial dysfunction., Materials and Methods: Metabolomic profiling, cellular oxygen consumption rate, mtROS, endothelial nitric oxide synthase phosphorylation, and the expression of vascular cell adhesion molecule-1 or intercellular adhesion molecule-1 were evaluated in bovine aortic ECs., Results: We found that LG increased mtROS generation in ECs; which was suppressed by overexpression of manganese superoxide dismutase. Comprehensive metabolic analysis using capillary electrophoresis-mass spectrometry and oxygen consumption rate assessment showed that the pathway from fatty acid to acetyl-CoA through fatty acid oxidation was upregulated in ECs under LG conditions. In addition, etomoxir, a specific inhibitor of the free fatty acid transporter, decreased LG-induced mtROS production. These results suggested that LG increased mtROS generation through activation of fatty acid oxidation. We further revealed that LG inhibited endothelial nitric oxide synthase phosphorylation, and increased the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. These effects were suppressed either by overexpression of manganese superoxide dismutase or by treatment with etomoxir., Conclusions: The activation of fatty acid oxidation followed by mtROS production could be one of the causes for endothelial dysfunction during hypoglycemia., (© 2017 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.)
- Published
- 2017
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208. Motility of Microtubules on the Inner Surface of Water-in-Oil Emulsion Droplets.
- Author
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Tsuji M, Rashedul Kabir AM, Ito M, Inoue D, Kokado K, Sada K, and Kakugo A
- Abstract
Water-in-oil emulsion systems have recently attracted much attention in various fields. However, functionalization of water-in-oil emulsion systems, which is required for expanding their applications in industries and research, has been challenging. We now demonstrate the functionalization of a water-in-oil emulsion system by anchoring a target protein molecule. A microtubule (MT)-associated motor protein kinesin-1 was successfully anchored to the inner surface of water-in-oil emulsion droplets by employing the specific interaction of nickel-nitrilotriacetic acid-histidine tag. The MTs exhibited a gliding motion on the kinesin-functionalized inner surface of the emulsion droplets, which confirmed the success of the functionalization of the water-in-oil emulsion system. This result would be beneficial in exploring the roles of biomolecular motor systems in the cellular events that take place at the cell membrane and might also contribute to expanding the nanotechnological applications of biomolecular motors and water-in-oil emulsion systems in the future.
- Published
- 2017
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209. Regulation of synaptic acetylcholine concentrations by acetylcholine transport in rat striatal cholinergic transmission.
- Author
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Muramatsu I, Uwada J, Masuoka T, Yoshiki H, Sada K, Lee KS, Nishio M, Ishibashi T, and Taniguchi T
- Subjects
- Animals, Biological Transport physiology, Choline metabolism, Hemicholinium 3 metabolism, Male, Organ Culture Techniques methods, Rats, Rats, Wistar, Acetylcholine metabolism, Cholinergic Neurons metabolism, Corpus Striatum metabolism, Presynaptic Terminals metabolism, Synapses metabolism, Synaptic Transmission physiology
- Abstract
In addition to hydrolysis by acetylcholine esterase (AChE), acetylcholine (ACh) is also directly taken up into brain tissues. In this study, we examined whether the uptake of ACh is involved in the regulation of synaptic ACh concentrations. Superfusion experiments with rat striatal segments pre-incubated with [
3 H]choline were performed using an ultra-mini superfusion vessel, which was developed to minimize superfusate retention within the vessel. Hemicholinium-3 (HC-3) at concentrations less than 1 μM, selectively inhibited the uptake of [3 H]choline by the high affinity-choline transporter 1 and had no effect on basal and electrically evoked [3 H]efflux in superfusion experiments. In contrast, HC-3 at higher concentrations, as well as tetraethylammonium (>10 μM), which inhibited the uptake of both [3 H]choline and [3 H]ACh, increased basal [3 H]overflow and potentiated electrically evoked [3 H]efflux. These effects of HC-3 and tetraethylammonium were also observed under conditions where tissue AChE was irreversibly inactivated by diisopropylfluorophosphate. Specifically, the potentiation of evoked [3 H]efflux was significantly higher in AChE-inactivated preparations and was attenuated by atropine. On the other hand, striatal segments pre-incubated with [3 H]ACh failed to increase [3 H]overflow in response to electrical stimulation. These results show that synaptic ACh concentrations are significantly regulated by the postsynaptic uptake of ACh, as well as by AChE hydrolysis and modulation of ACh release mediated through presynaptic muscarinic ACh receptors. In addition, these data suggest that the recycling of ACh-derived choline may be minor in cholinergic terminals. This study reveals a new mechanism of cholinergic transmission in the central nervous system., (© 2017 International Society for Neurochemistry.)- Published
- 2017
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210. Organic Reaction as a Stimulus for Polymer Phase Separation.
- Author
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Naya M, Hamano Y, Kokado K, and Sada K
- Abstract
Molecular design of stimuli-sensitive polymers has been attracting considerable interest of chemists because of their latent ability to achieve smart materials. Heat, light, pH, and chemicals have been often utilized as a stimuli-inducing polymer phase transition from solution to aggregation and vice versa. In this report, as a new trigger for lower critical solution temperature (LCST)-type polymer phase transition, we introduce organic reaction of small organic molecules, not to the polymer chain itself. The addition of the reactant for the "effector", which can interact with the polymer chain for increasing the compatibility of the polymer chain with the media, caused a polymer phase separation, due to reduction of the solvation ability of the effector to the polymer chain. In other words, decrease of the "effector" concentration induced the polymer phase separation. Within our knowledge, this is the first report to connect a polymer phase separation with organic reaction dynamics. This process will be the first step for the development of artificial allosteric enzyme mimics from a combination of a simple synthetic polymer and a product or reactant in organic reactions.
- Published
- 2017
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211. Syk-dependent tyrosine phosphorylation of 3BP2 is required for optimal FcRγ-mediated phagocytosis and chemokine expression in U937 cells.
- Author
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Chihara K, Kato Y, Yoshiki H, Takeuchi K, Fujieda S, and Sada K
- Subjects
- Adaptor Proteins, Signal Transducing chemistry, Adaptor Proteins, Signal Transducing genetics, Amino Acid Sequence, Chemokines metabolism, Humans, Mutation, Phosphorylation, Protein Binding, Protein Interaction Domains and Motifs, Receptors, Fc chemistry, Receptors, Fc genetics, Syk Kinase chemistry, Syk Kinase genetics, U937 Cells, src Homology Domains, Adaptor Proteins, Signal Transducing metabolism, Chemokines genetics, Gene Expression Regulation, Phagocytosis, Receptors, Fc metabolism, Syk Kinase metabolism, Tyrosine metabolism
- Abstract
The adaptor protein c-Abl SH3 domain binding protein-2 (3BP2) is tyrosine phosphorylated by Syk in response to cross-linking of antigen receptors, which in turn activates various immune responses. Recently, a study using the mouse model of cherubism, a dominant inherited disorder caused by mutations in the gene encoding 3BP2, showed that 3BP2 is involved in the regulation of phagocytosis mediated by Fc receptor for IgG (FcγR) in macrophages. However, the molecular mechanisms underlying 3BP2-mediated regulation of phagocytosis and the physiological relevance of 3BP2 tyrosine phosphorylation remains elusive. In this study, we established various gene knockout U937 cell lines using the CRISPR/Cas9 system and found that 3BP2 is rapidly tyrosine phosphorylated by Syk in response to cross-linking of FcγRI. Depletion of 3BP2 caused significant reduction in the Fc receptor γ chain (FcRγ)-mediated phagocytosis in addition to the FcγRI-mediated induction of chemokine mRNA for IL-8, CCL3L3 and CCL4L2. Syk-dependent tyrosine phosphorylation of 3BP2 was required for overcoming these defects. Finally, we found that the PH and SH2 domains play important roles on FcγRI-mediated tyrosine phosphorylation of 3BP2 in HL-60 cells. Taken together, these results indicate that Syk-dependent tyrosine phosphorylation of 3BP2 is required for optimal FcRγ-mediated phagocytosis and chemokine expression.
- Published
- 2017
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212. Electrochemical potassium-ion intercalation in Na x CoO 2 : a novel cathode material for potassium-ion batteries.
- Author
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Sada K, Senthilkumar B, and Barpanda P
- Abstract
Reversible electrochemical potassium-ion intercalation in P2-type Na
x CoO2 was examined for the first time. Hexagonal Na0.84 CoO2 platelets prepared by a solution combustion synthesis technique were found to work as an efficient host for K+ intercalation. They deliver a high reversible capacity of 82 mA h g-1 , good rate capability and excellent cycling performance up to 50 cycles.- Published
- 2017
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213. High-Resolution Imaging of a Single Gliding Protofilament of Tubulins by HS-AFM.
- Author
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Keya JJ, Inoue D, Suzuki Y, Kozai T, Ishikuro D, Kodera N, Uchihashi T, Kabir AMR, Endo M, Sada K, and Kakugo A
- Subjects
- Microtubules ultrastructure, Motion, Single Molecule Imaging, Kinesins ultrastructure, Microscopy, Atomic Force methods, Tubulin ultrastructure
- Abstract
In vitro gliding assay of microtubules (MTs) on kinesins has provided us with valuable biophysical and chemo-mechanical insights of this biomolecular motor system. Visualization of MTs in an in vitro gliding assay has been mainly dependent on optical microscopes, limited resolution of which often render them insufficient sources of desired information. In this work, using high speed atomic force microscopy (HS-AFM), which allows imaging with higher resolution, we monitored MTs and protofilaments (PFs) of tubulins while gliding on kinesins. Moreover, under the HS-AFM, we also observed splitting of gliding MTs into single PFs at their leading ends. The split single PFs interacted with kinesins and exhibited translational motion, but with a slower velocity than the MTs. Our investigation at the molecular level, using the HS-AFM, would provide new insights to the mechanics of MTs in dynamic systems and their interaction with motor proteins.
- Published
- 2017
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214. Activation of muscarinic receptors prevents TNF-α-mediated intestinal epithelial barrier disruption through p38 MAPK.
- Author
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Uwada J, Yazawa T, Islam MT, Khan MRI, Krug SM, Fromm M, Karaki SI, Suzuki Y, Kuwahara A, Yoshiki H, Sada K, Muramatsu I, and Taniguchi T
- Subjects
- ADAM17 Protein genetics, ADAM17 Protein metabolism, Epithelial Cells metabolism, ErbB Receptors metabolism, HT29 Cells, Humans, Inflammatory Bowel Diseases genetics, Inflammatory Bowel Diseases pathology, Intestinal Mucosa metabolism, MAP Kinase Signaling System genetics, Phosphorylation, Receptor, Muscarinic M3 metabolism, Receptors, G-Protein-Coupled genetics, Receptors, G-Protein-Coupled metabolism, Receptors, Histamine H1 genetics, Receptors, Histamine H1 metabolism, Receptors, Tumor Necrosis Factor genetics, Receptors, Tumor Necrosis Factor metabolism, Signal Transduction genetics, Tumor Necrosis Factor-alpha metabolism, p38 Mitogen-Activated Protein Kinases metabolism, ErbB Receptors genetics, Receptor, Muscarinic M3 genetics, Tumor Necrosis Factor-alpha genetics, p38 Mitogen-Activated Protein Kinases genetics
- Abstract
Intestinal epithelial cells form a tight barrier to act as selective physical barriers, repelling hostile substances. Tumor necrosis factor-α (TNF-α) is a well characterized pro-inflammatory cytokine which can compromise intestinal barrier function and the suppression of TNF-α function is important for treatment of inflammatory bowel disease (IBD). In this study, we investigated the contribution of G-protein-coupled receptor (GPCR)-induced signalling pathways to the maintenance of epithelial barrier function. We first demonstrated the existence of functional muscarinic M3 and histamine H1 receptors in colonic epithelial cell HT-29/B6. As we previously reported, muscarinic M3 receptor prevented TNF-α-induced barrier disruption through acceleration of TNF receptor (TNFR) shedding which is carried out by TNF-α converting enzyme (TACE). M3 receptor-mediated suppression of TNF-α function depends on Gα
q/11 protein, however, histamine H1 receptor could not ameliorate TNF-α function, while which could induce Gαq/11 dependent intracellular Ca2+ mobilization. We found that p38 MAPK was predominantly phosphorylated by M3 receptor through Gαq/11 protein, whereas H1 receptor barely upregulated the phosphorylation. Inhibition of p38 MAPK abolished M3 receptor-mediated TNFR shedding and suppression of TNF-α-induced NF-κB signalling. The p38 MAPK was also involved in TACE- mediated EGFR transactivation followed by ERK1/2 phosphorylation. These results indicate that not H1 but M3 receptor-induced activation of p38 MAPK might contribute to the maintenance of epithelial barrier function through down-regulation of TNF-α signalling and activation of EGFR., (Copyright © 2017 Elsevier Inc. All rights reserved.)- Published
- 2017
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215. Pyrolysis of Helical Coordination Polymers for Metal-Sulfide-Based Helices with Broadband Chiroptical Activity.
- Author
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Hirai K, Yeom B, and Sada K
- Abstract
Fabrication of chiroptical materials with broadband response in the visible light region is vital to fully realize their potential applications. One way to achieve broadband chiroptical activity is to fabricate chiral nanostructures from materials that exhibit broadband absorption in the visible light region. However, the compounds used for chiroptical materials have predominantly been limited to materials with narrowband spectral response. Here, we synthesize Ag
2 S-based nanohelices derived from helical coordination polymers. The right- and left-handed coordination helices used as precursors are prepared from l- and d-glutathione with Ag+ and a small amount of Cu2+ . The pyrolysis of the coordination helices yields right- and left-handed helices of Cu0.12 Ag1.94 S/C, which exhibit chiroptical activity spanning the entire visible light region. Finite element method simulations substantiate that the broadband chiroptical activity is attributed to synergistic broadband light absorption and light scattering. Furthermore, another series of Cu0.10 Ag1.90 S/C nanohelices are synthesized by choosing the l- or d-Glu-Cys as starting materials. The pitch length of nanohelicies is controlled by changing the peptides, which alters their chiroptical properties. The pyrolysis of coordination helices enables one to fabricate helical Ag2 S-based materials that enable broadband chiroptical activity but have not been explored owing to the lack of synthetic routes.- Published
- 2017
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216. Association of C-Type Lectin Mincle with FcεRIβγ Subunits Leads to Functional Activation of RBL-2H3 Cells through Syk.
- Author
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Honjoh C, Chihara K, Yoshiki H, Yamauchi S, Takeuchi K, Kato Y, Hida Y, Ishizuka T, and Sada K
- Subjects
- Animals, Cell Degranulation, Cell Line, Enzyme Activation, Extracellular Signal-Regulated MAP Kinases metabolism, Gene Expression Regulation, Mast Cells metabolism, Mast Cells physiology, Mutation genetics, NFATC Transcription Factors metabolism, Phospholipase C gamma metabolism, Phosphorylation, Phosphotyrosine metabolism, Protein Binding, Rats, Signal Transduction, Lectins, C-Type metabolism, Protein Subunits metabolism, Receptors, IgE metabolism, Receptors, Immunologic metabolism, Syk Kinase metabolism
- Abstract
Macrophage-inducible C-type lectin (Mincle) interacts with the γ-subunit of high-affinity IgE receptor (FcεRIγ) and activates Syk by recognizing its specific ligand, trehalose-6,6'-dimycolate, a glycolipid produced by Mycobacterium tuberculosis. It has been suggested that mast cells participate in the immune defense against pathogenic microbes including M. tuberculosis, although the functions are still uncertain. In this study, we examined the Mincle-mediated signaling pathway and cellular responses using RBL-2H3 cells. Mincle formed a protein complex with not only FcεRIγ but also FcεRIβ in a stable cell line expressing myc-tagged Mincle. In addition, engagement of Mincle increased the levels of protein tyrosine phosphorylation and ERK phosphorylation. A pull-down assay demonstrated that cross-linking of Mincle induced binding of FcεRIβγ subunits to the Src homology 2 domain of Syk. Pharmacological and genetic studies indicated that activation of Syk was critical for Mincle-mediated activation of phospholipase Cγ2, leading to the activation of ERK and nuclear factor of activated T cells. Moreover, engagement of Mincle efficiently induced up-regulation of characteristic mast cell genes in addition to degranulation. Taken together, our present results suggest that mast cells contribute to Mincle-mediated immunity through Syk activation triggered by association with the FcεRIβγ complex.
- Published
- 2017
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217. Disassembly Control of Saccharide-Based Amphiphiles Driven by Electrostatic Repulsion.
- Author
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Yamada T, Kokado K, and Sada K
- Subjects
- Copper, Hydrophobic and Hydrophilic Interactions, Static Electricity, Carbohydrates chemistry
- Abstract
According to the design of disassembly using electrostatic repulsion, novel amphiphiles consisting of a lipophilic ion part and a hydrophilic saccharide part were synthesized via the facile copper-catalyzed click reaction, and their molecular assemblies in water and chloroform were studied. The amphiphiles exhibited a molecular orientation opposite to that of the conventional amphiphiles in each case. ζ Potential measurements indicated that the lipophilic ion part is exposed outside in chloroform. The size of a solvophobic part in the amphiphiles dominates the size of an assembling structure; that is, in water, these amphiphiles tethering different lengths of the saccharide part exhibited almost identical assembling size, whereas in chloroform, the size depends on the length of the saccharide part in the amphiphiles.
- Published
- 2017
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218. Joint Loading in the Sagittal Plane During Gait Is Associated With Hip Joint Abnormalities in Patients With Femoroacetabular Impingement.
- Author
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Samaan MA, Schwaiger BJ, Gallo MC, Sada K, Link TM, Zhang AL, Majumdar S, and Souza RB
- Subjects
- Activities of Daily Living, Adult, Biomechanical Phenomena, California, Female, Foot Joints abnormalities, Humans, Knee Joint abnormalities, Male, Middle Aged, Range of Motion, Articular, Walking, Femoracetabular Impingement physiopathology, Foot Joints physiology, Knee Joint physiology
- Abstract
Background: Femoroacetabular impingement (FAI) is a morphological abnormality of the hip joint that results in functional impairments during various activities of daily living (ADL) such as walking. Purpose/Hypothesis: The purpose of this study was to determine if lower extremity joint loading differed between patients with FAI and controls and to determine whether these altered biomechanical parameters were associated with intra-articular abnormalities. It was hypothesized that patients with FAI would exhibit altered lower extremity joint loading during walking when compared with healthy controls and that these altered joint loading patterns would be associated with intra-articular abnormalities., Study Design: Controlled laboratory study., Methods: Lower extremity kinetics was assessed during walking at a self-selected speed in 15 presurgical patients with FAI and 34 healthy controls matched for age and body mass index. All participants underwent unilateral hip magnetic resonance imaging (MRI) to assess hip joint abnormalities. Hip joint abnormalities were assessed using a semiquantitative MRI-based scoring system. Self-reported outcomes of pain and function were obtained using the Hip disability and Osteoarthritis Outcome Score (HOOS), and physical performance was measured using the 6-minute walk test (6MWT). Group differences were assessed using an independent t test and analysis of variance. In the patients with FAI, associations of joint kinetics with HOOS subscores and intra-articular abnormalities were assessed using the Pearson ( r) and Spearman (ρ) correlation coefficients, respectively., Results: Compared with the control group, the FAI group exhibited a significantly increased severity of acetabular (FAI: 1.87 ± 1.55; control: 0.47 ± 0.79; P < .001) and femoral (FAI: 3.27 ± 2.79; control: 1.21 ± 1.55; P = .002) cartilage abnormalities, increased levels of pain (FAI: 65.0 ± 18.8; control: 98.2 ± 3.4; P = .001), and reduced function (FAI: 67.2 ± 21.5; control: 98.9 ± 3.4; P < .001) but similar walking speeds (FAI: 1.55 ± 0.19 m/s; control: 1.63 ± 0.22 m/s; P = .20) and 6MWT performance (FAI: 628.0 ± 91.2 m; control: 667.2 ± 73.4 m; P = .13). The FAI group demonstrated increased hip flexion moment impulses (FAI: 0.14 ± 0.04 N·m·s/kg; control: 0.11 ± 0.03 N·m·s/kg; P = .03), peak ankle dorsiflexion moments (FAI: 1.64 ± 0.16 N·m/kg; control: 1.46 ± 0.31 N·m/kg; P = .04), and ankle dorsiflexion moment impulses (FAI: 0.39 ± 0.07 N·m·s/kg; control: 0.31 ± 0.07 N·m·s/kg; P = .01) compared with the control group. Within the FAI group, an increased hip flexion moment impulse during walking was significantly correlated with increased pain ( r = -0.60, P = .03), decreased ADL ( r = -0.57, P = .04), and increased severity of acetabular cartilage abnormalities (ρ = 0.82, P < .01)., Conclusion: Patients with FAI exhibited altered hip and ankle joint loading patterns during walking. These data suggest that patients with FAI demonstrate both local and distal joint alterations during walking and that hip joint loading is directly related to hip joint abnormalities., Clinical Relevance: The results of this study suggest that the hip flexion moment impulse may be an important biomechanical parameter to understand FAI, as the hip flexion moment impulse during walking was shown to be directly related to hip joint abnormalities on MRI.
- Published
- 2017
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219. Anisotropically Swelling Gels Attained through Axis-Dependent Crosslinking of MOF Crystals.
- Author
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Ishiwata T, Kokado K, and Sada K
- Abstract
Anisotropically deforming objects have attracted considerable interest for use in molecular machines and artificial muscles. Herein, we focus on a new approach based on the crystal crosslinking of organic ligands in a pillared-layer metal-organic framework (PLMOF). The approach involves the transformation from crosslinked PLMOF to polymer gels through hydrolysis of the coordination bonds between the organic ligands and metal ions, giving a network polymer that exhibits anisotropic swelling. The anisotropic monomer arrangement in the PLMOF underwent axis-dependent crosslinking to yield anisotropically swelling gels. Therefore, the crystal crosslinking of MOFs should be a useful method for creating actuators with designable deformation properties., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2017
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220. Liquefaction-induced emission enhancement of tetraphenylethene derivatives.
- Author
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Machida T, Taniguchi R, Oura T, Sada K, and Kokado K
- Abstract
A typical AIE dye, TPE, was liquefied by attaching long and branched alkyl chains. The obtained liquid dye showed intense emission compared to the solid dye or TPE. The linkage between TPE and the alkyl chain led to significant difference in their photoluminescent and thermal properties.
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- 2017
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221. Crystal Crosslinked Gels with Aggregation-Induced Emissive Crosslinker Exhibiting Swelling Degree-Dependent Photoluminescence.
- Author
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Oura T, Taniguchi R, Kokado K, and Sada K
- Abstract
The synthesis and photoluminescence properties of crystal crosslinked gels (CCGs) with an aggregation-induced emission (AIE) active crosslinker derived from tetraphenylethene (TPE) is discussed in this article. The CCG was prepared from a metal organic framework (MOF) with large pore aperture to allow the penetration of TPE crosslinker. The obtained CCG possessed a rectangular shape originated from the parent MOF, KUMOF. The CCG showed stimuli-responsive photoluminescence behavior depending on the swelling degree, thus the photoluminescence intensity was higher at higher swelling degree. By changing the solvent, water content, or ionic strength, the photoluminescence intensity was controllable, accompanying the change of swelling degree. Moreover, emission color tuning was also achieved by the introduction of luminescent rare earth ions to form a coordination bonding with residual carboxylate inside the CCG.
- Published
- 2017
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222. STAT1 is essential for the inhibition of hepatitis C virus replication by interferon-λ but not by interferon-α.
- Author
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Yamauchi S, Takeuchi K, Chihara K, Honjoh C, Kato Y, Yoshiki H, Hotta H, and Sada K
- Subjects
- Antiviral Agents administration & dosage, Carcinoma, Hepatocellular pathology, Carcinoma, Hepatocellular virology, DNA Replication genetics, Hepacivirus pathogenicity, Hepatitis C genetics, Hepatitis C pathology, Hepatitis C virology, Humans, Interferon Regulatory Factor-1 genetics, RNA, Viral genetics, Virus Replication genetics, Hepacivirus genetics, Interferon-alpha genetics, Interferon-gamma genetics, STAT1 Transcription Factor genetics, STAT2 Transcription Factor genetics
- Abstract
Interferon-α (IFN-α) and IFN-λ are structurally distinct cytokines that bind to different receptors, but induce expression of similar sets of genes through Janus kinase (JAK)-signal transducers and activators of transcription (STAT) pathways. The difference between IFN-α and IFN-λ signaling remains poorly understood. Here, using the CRISPR/Cas9 system, we examine the role of STAT1 and STAT2 in the inhibition of hepatitis C virus (HCV) replication by IFN-α and IFN-λ. Treatment with IFN-α increases expression of IFN-stimulated genes (ISGs) such as double-stranded RNA-activated protein kinase (PKR) and decreases viral RNA and protein levels in HCV-infected Huh-7.5 human hepatoma cells. These responses are only partially attenuated by knockout of STAT1 but are abolished by knockout of STAT2. In contrast, the inhibition of HCV replication by IFN-λ is abolished by knockout of STAT1 or STAT2. Microarray analysis reveals that IFN-α but not IFN-λ can induce expression of the majority of ISGs in STAT1 knockout cells. These findings suggest that IFN-α can inhibit HCV replication through a STAT2-dependent but STAT1-independent pathway, whereas IFN-λ induces ISG expression and inhibits HCV replication exclusively through a STAT1- and STAT2-dependent pathway.
- Published
- 2016
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223. Buckling of microtubules on elastic media via breakable bonds.
- Author
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Afrin T, Kabir AM, Sada K, Kakugo A, and Nitta T
- Subjects
- Compressive Strength, Computer Simulation, Elasticity, Kinesins chemistry, Kinesins metabolism, Microtubules chemistry, Microtubules metabolism
- Abstract
Buckling of microtubules observed in cells has been reconstructed on a two-dimensional elastic medium consisting of kinesins grafted over compressible substrates, enabling precise control of experimental conditions and quantitative analysis. However, interpretations of the observations have ambiguities due to inevitable experimental difficulties. In this study, with computer simulations, we investigated importance of the mode of interaction of microtubule with elastic medium in the buckling behavior of microtubule. By taking into consideration of forced-induced detachments of kinesins from microtubules, our simulations reproduced the previous experimental results, and showed deviations from predictions of the elastic foundation model. On the other hand, with hypothetical linkers permanently bound to microtubules, our simulation reproduced the predictions of the elastic foundation model. By analyzing the results of the simulations, we investigated as to why the difference arose. These findings indicate the importance of the mode of interaction of microtubule with the medium in the buckling behavior of microtubule. Our findings would bring new insights on buckling of microtubules in living cells., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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224. Pharmacological evidence of specific acetylcholine transport in rat cerebral cortex and other brain regions.
- Author
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Muramatsu I, Yoshiki H, Uwada J, Masuoka T, Sada K, Taniguchi T, and Nishio M
- Subjects
- Animals, Biological Transport drug effects, Biological Transport physiology, Brain drug effects, Brain metabolism, Cerebral Cortex drug effects, Colon drug effects, Colon metabolism, Dose-Response Relationship, Drug, Heart drug effects, Heart physiology, Isoflurophate pharmacology, Kidney drug effects, Kidney metabolism, Male, Rats, Rats, Wistar, Acetylcholine antagonists & inhibitors, Acetylcholine metabolism, Cerebral Cortex metabolism, Cholinesterase Inhibitors pharmacology
- Abstract
Functional acetylcholine receptors (AChRs) were recently demonstrated to exist not only in the plasma membrane but also intracellularly in brain tissues. In order to activate intracellular AChRs, endogenous hydrophilic ACh must cross the plasma membrane. Here, we examined the pharmacological characteristics of this process, including whether it is mediated by active ACh uptake. When ACh esterase (AChE) was suppressed by diisopropylfluorophosphate, [
3 H]ACh was effectively taken up into segments of rat cerebral cortex and other brain regions, in contrast to peripheral tissues such as liver and kidney. The uptake of [3 H]ACh in rat cerebral cortex was temperature-dependent, and the uptake capacity was comparable to that of [3 H]choline. However, [3 H]ACh uptake was inhibited by lower concentrations of ACh, carbachol, tetraethylammonium (TEA), compared with uptake of [3 H]choline. Uptake of [3 H]ACh was also inhibited by several organic cations, including choline, hemicholinium-3 (HC-3), quinidine, decynium 22, clonidine, diphenhydramine, but was little affected by some amino acids and biogenic amines, corticosterone, spermine, atropine, and tetrodotoxin. Unlike diisopropylfluorophosphate, several ACh esterase inhibitors, including drugs for Alzheimer's disease, such as donepezil, galantamine, and rivastigmine, also suppressed the uptake of [3 H]ACh, but not [3 H]choline. These results indicate that in the brain, ACh is specifically taken up through a unique transport system with different pharmacological properties from known organic cation transporters (OCTs), and suggest that this mechanism may be involved in intracellular cholinergic transmission in the brain., (© 2016 International Society for Neurochemistry.)- Published
- 2016
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225. Sensing surface mechanical deformation using active probes driven by motor proteins.
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Inoue D, Nitta T, Kabir AMR, Sada K, Gong JP, Konagaya A, and Kakugo A
- Subjects
- Adenosine Triphosphate chemistry, Animals, Brain metabolism, Dimethylpolysiloxanes chemistry, Dyneins chemistry, Elasticity, Green Fluorescent Proteins chemistry, Humans, Kinesins chemistry, Materials Testing, Microtubules chemistry, Myosins chemistry, Reactive Oxygen Species chemistry, Stress, Mechanical, Swine, Cytoskeleton chemistry, Molecular Motor Proteins chemistry
- Abstract
Studying mechanical deformation at the surface of soft materials has been challenging due to the difficulty in separating surface deformation from the bulk elasticity of the materials. Here, we introduce a new approach for studying the surface mechanical deformation of a soft material by utilizing a large number of self-propelled microprobes driven by motor proteins on the surface of the material. Information about the surface mechanical deformation of the soft material is obtained through changes in mobility of the microprobes wandering across the surface of the soft material. The active microprobes respond to mechanical deformation of the surface and readily change their velocity and direction depending on the extent and mode of surface deformation. This highly parallel and reliable method of sensing mechanical deformation at the surface of soft materials is expected to find applications that explore surface mechanics of soft materials and consequently would greatly benefit the surface science.
- Published
- 2016
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226. Normothermic thyroid storm: an unusual presentation.
- Author
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Sabir AA, Sada K, Yusuf BO, and Aliyu I
- Abstract
Thyroid storm is a rare life-threatening emergency due to thyrotoxicosis. A 30-year-old female presented with restlessness, tachycardia and vomiting but with normothermia which is an unusual presentation. There is the need for clinicians to be aware of atypical clinical features that can make the diagnosis of thyroid storm difficult.
- Published
- 2016
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227. Hyperglycemia Induces Cellular Hypoxia through Production of Mitochondrial ROS Followed by Suppression of Aquaporin-1.
- Author
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Sada K, Nishikawa T, Kukidome D, Yoshinaga T, Kajihara N, Sonoda K, Senokuchi T, Motoshima H, Matsumura T, and Araki E
- Subjects
- 8-Hydroxy-2'-Deoxyguanosine, Animals, Apoptosis drug effects, Blotting, Western, Cattle, Cell Hypoxia, Cell Line, Deoxyguanosine analogs & derivatives, Deoxyguanosine biosynthesis, Diabetes Mellitus, Experimental complications, Diabetes Mellitus, Experimental metabolism, Endothelial Cells drug effects, Endothelial Cells metabolism, Endothelin-1 genetics, Endothelin-1 metabolism, Fibronectins genetics, Fibronectins metabolism, Glucose pharmacology, Hyperglycemia complications, Hypoxia metabolism, Mice, Inbred C57BL, Mice, Transgenic, Reverse Transcriptase Polymerase Chain Reaction, Superoxide Dismutase genetics, Superoxide Dismutase metabolism, Hyperglycemia metabolism, Mitochondria metabolism, Reactive Oxygen Species metabolism
- Abstract
We previously proposed that hyperglycemia-induced mitochondrial reactive oxygen species (mtROS) generation is a key event in the development of diabetic complications. Interestingly, some common aspects exist between hyperglycemia and hypoxia-induced phenomena. Thus, hyperglycemia may induce cellular hypoxia, and this phenomenon may also be involved in the pathogenesis of diabetic complications. In endothelial cells (ECs), cellular hypoxia increased after incubation with high glucose (HG). A similar phenomenon was observed in glomeruli of diabetic mice. HG-induced cellular hypoxia was suppressed by mitochondria blockades or manganese superoxide dismutase (MnSOD) overexpression, which is a specific SOD for mtROS. Overexpression of MnSOD also increased the expression of aquaporin-1 (AQP1), a water and oxygen channel. AQP1 overexpression in ECs suppressed hyperglycemia-induced cellular hypoxia, endothelin-1 and fibronectin overproduction, and apoptosis. Therefore, hyperglycemia-induced cellular hypoxia and mtROS generation may promote hyperglycemic damage in a coordinated manner.
- Published
- 2016
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228. Mesogenic Polyelectrolyte Gels Absorb Organic Solvents and Liquid Crystalline Molecules.
- Author
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Nishikori Y, Iseda K, Kokado K, and Sada K
- Abstract
In this paper, mesogenic polyelectrolyte gels (MPEgels) tethering mesogenic groups on the side chains were synthesized from a mesogenic monomer and ionic monomer via a conventional radical polymerization process. The obtained MPEgels absorbed various organic solvents in a wide range of dielectric constants from chloroform (ε = 7.6) to DMSO (ε = 46.5). The electrostatic repulsion among the polymer chains and the osmotic pressure between the interior and exterior of the MPEgel is responsible for the high swelling ability, revealed by the common ion effect using tetra( n -hexyl)ammonium tetra(3,5-bis(trifluoromethyl)phenylborate (THATFPB). The obtained MPEgels could also absorb liquid crystalline molecules such as 4-cyano-4'-pentylbiphenyl (5CB), analogously caused by the above-mentioned polyelectrolyte characteristic. The MPEgels exhibited liquid crystal transition temperature ( T
NI ) on differential scanning calorimetry (DSC) measurement, and the increase of the ionic group content lowered TNI . The MPEgels absorbing liquid crystalline molecules exhibited differing TNI , dependent on the compatibility of the mesogenic group on the side chain to the liquid crystalline molecule.- Published
- 2016
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229. Enhanced dynamic instability of microtubules in a ROS free inert environment.
- Author
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Islam MS, Kabir AM, Inoue D, Sada K, and Kakugo A
- Subjects
- Animals, Swine, Tubulin chemistry, Tubulin isolation & purification, Tubulin metabolism, Microtubules metabolism, Reactive Oxygen Species
- Abstract
Reactive oxygen species (ROS), one of the regulators in various biological processes, have recently been suspected to modulate microtubule (MT) dynamics in cells. However due to complicated cellular environment and unavailability of any in vitro investigation, no detail is understood yet. Here, by performing simple in vitro investigations, we have unveiled the effect of ROS on MT dynamics. By studying dynamic instability of MTs in a ROS free environment and comparing with that in the presence of ROS, we disclosed that MTs showed enhanced dynamics in the ROS free environment. All the parameters that define dynamic instability of MTs e.g., growth and shrinkage rates, rescue and catastrophe frequencies were significantly affected by the presence of ROS. This work clearly reveals the role of ROS in modulating MT dynamics in vitro, and would be a great help in understanding the role of ROS in regulation of MT dynamics in cells., (Copyright © 2015. Published by Elsevier B.V.)
- Published
- 2016
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230. Gas-generated thermal oxidation of a coordination cluster for an anion-doped mesoporous metal oxide.
- Author
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Hirai K, Isobe S, and Sada K
- Abstract
Central in material design of metal oxides is the increase of surface area and control of intrinsic electronic and optical properties, because of potential applications for energy storage, photocatalysis and photovoltaics. Here, we disclose a facile method, inspired by geochemical process, which gives rise to mesoporous anion-doped metal oxides. As a model system, we demonstrate that simple calcination of a multinuclear coordination cluster results in synchronic chemical reactions: thermal oxidation of Ti8O10(4-aminobenzoate)12 and generation of gases including amino-group fragments. The gas generation during the thermal oxidation of Ti8O10(4-aminobenzoate)12 creates mesoporosity in TiO2. Concurrently, nitrogen atoms contained in the gases are doped into TiO2, thus leading to the formation of mesoporous N-doped TiO2. The mesoporous N-doped TiO2 can be easily synthesized by calcination of the multinuclear coordination cluster, but shows better photocatalytic activity than the one prepared by a conventional sol-gel method. Owing to an intrinsic designability of coordination compounds, this facile synthetic will be applicable to a wide range of metal oxides and anion dopants.
- Published
- 2015
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231. Activation of muscarinic cholinoceptor ameliorates tumor necrosis factor-α-induced barrier dysfunction in intestinal epithelial cells.
- Author
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Khan MR, Uwada J, Yazawa T, Islam MT, Krug SM, Fromm M, Karaki S, Suzuki Y, Kuwahara A, Yoshiki H, Sada K, Muramatsu I, Anisuzzaman AS, and Taniguchi T
- Subjects
- Animals, Colon cytology, HT29 Cells, Humans, Intestinal Mucosa drug effects, Intestinal Mucosa metabolism, NF-kappa B metabolism, Rats, Receptors, Tumor Necrosis Factor, Type I metabolism, Signal Transduction drug effects, Intestinal Mucosa cytology, Receptors, Muscarinic metabolism, Tumor Necrosis Factor-alpha pharmacology
- Abstract
Impaired intestinal barrier function is one of the critical issues in inflammatory bowel diseases. The aim of this study is to investigate muscarinic cholinoceptor (mAChR)-mediated signaling for the amelioration of cytokine-induced barrier dysfunction in intestinal epithelium. Rat colon challenged with TNF-α and interferon γ reduced transepithelial electrical resistance (TER). This barrier injury was attenuated by muscarinic stimulation. In HT-29/B6 intestinal epithelial cells, muscarinic stimulation suppressed TNF-α-induced activation of NF-κB signaling and barrier disruption. Finally, muscarinic stimulation promoted the shedding of TNFR1, which would be a mechanism for the attenuation of TNF-α/NF-κB signaling and barrier disruption via mAChR., (Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)
- Published
- 2015
- Full Text
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232. Buckling of Microtubules on a 2D Elastic Medium.
- Author
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Kabir AM, Inoue D, Afrin T, Mayama H, Sada K, and Kakugo A
- Subjects
- Animals, Compressive Strength, Dimethylpolysiloxanes chemistry, Elasticity, Kinesins chemistry, Microtubules ultrastructure, Models, Biological, Protein Structure, Quaternary, Stress, Mechanical, Sus scrofa, Microtubules chemistry
- Abstract
We have demonstrated compression stress induced mechanical deformation of microtubules (MTs) on a two-dimensional elastic medium and investigated the role of compression strain, strain rate, and a MT-associated protein in the deformation of MTs. We show that MTs, supported on a two-dimensional substrate by a MT-associated protein kinesin, undergo buckling when they are subjected to compression stress. Compression strain strongly affects the extent of buckling, although compression rate has no substantial effect on the buckling of MTs. Most importantly, the density of kinesin is found to play the key role in determining the buckling mode of MTs. We have made a comparison between our experimental results and the 'elastic foundation model' that theoretically predicts the buckling behavior of MTs and its connection to MT-associated proteins. Taking into consideration the role of kinesin in altering the mechanical property of MTs, we are able to explain the buckling behavior of MTs by the elastic foundation model. This work will help understand the buckling mechanism of MTs and its connection to MT-associated proteins or surrounding medium, and consequently will aid in obtaining a meticulous scenario of the compression stress induced deformation of MTs in cells.
- Published
- 2015
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233. Depletion force induced collective motion of microtubules driven by kinesin.
- Author
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Inoue D, Mahmot B, Kabir AM, Farhana TI, Tokuraku K, Sada K, Konagaya A, and Kakugo A
- Subjects
- Animals, Humans, Kinesins chemistry, Microtubules chemistry
- Abstract
Collective motion is a fascinating example of coordinated behavior of self-propelled objects, which is often associated with the formation of large scale patterns. Nowadays, the in vitro gliding assay is being considered a model system to experimentally investigate various aspects of group behavior and pattern formation by self-propelled objects. In the in vitro gliding assay, cytoskeletal filaments F-actin or microtubules are driven by the surface immobilized associated biomolecular motors myosin or dynein respectively. Although the F-actin/myosin or microtubule/dynein system was found to be promising in understanding the collective motion and pattern formation by self-propelled objects, the most widely used biomolecular motor system microtubule/kinesin could not be successfully employed so far in this regard. Failure in exhibiting collective motion by kinesin driven microtubules is attributed to the intrinsic properties of kinesin, which was speculated to affect the behavior of individual gliding microtubules and mutual interactions among them. In this work, for the first time, we have demonstrated the collective motion of kinesin driven microtubules by regulating the mutual interaction among the gliding microtubules, by employing a depletion force among them. Proper regulation of the mutual interaction among the gliding microtubules through the employment of the depletion force was found to allow the exhibition of collective motion and stream pattern formation by the microtubules. This work offers a universal means for demonstrating the collective motion using the in vitro gliding assay of biomolecular motor systems and will help obtain a meticulous understanding of the fascinating coordinated behavior and pattern formation by self-propelled objects.
- Published
- 2015
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234. Hepatitis C Virus Particle Assembly Involves Phosphorylation of NS5A by the c-Abl Tyrosine Kinase.
- Author
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Yamauchi S, Takeuchi K, Chihara K, Sun X, Honjoh C, Yoshiki H, Hotta H, and Sada K
- Subjects
- Animals, COS Cells, Cell Line, Tumor, Chlorocebus aethiops, HEK293 Cells, Hepacivirus genetics, Hepacivirus physiology, Host-Pathogen Interactions, Humans, Immunoblotting, Microscopy, Confocal, Phosphorylation, Proto-Oncogene Proteins c-abl genetics, RNA Interference, RNA, Viral genetics, RNA, Viral metabolism, Reverse Transcriptase Polymerase Chain Reaction, Tyrosine genetics, Tyrosine metabolism, Viral Nonstructural Proteins genetics, Virion genetics, Virion metabolism, Virion physiology, Hepacivirus metabolism, Proto-Oncogene Proteins c-abl metabolism, Viral Nonstructural Proteins metabolism, Virus Assembly
- Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is thought to regulate the replication of viral RNA and the assembly of virus particles in a serine/threonine phosphorylation-dependent manner. However, the host kinases that phosphorylate NS5A have not been fully identified. Here, we show that HCV particle assembly involves the phosphorylation of NS5A by the c-Abl tyrosine kinase. Pharmacological inhibition or knockdown of c-Abl reduces the production of infectious HCV (J6/JFH1) particles in Huh-7.5 cells without markedly affecting viral RNA translation and replication. NS5A is tyrosine-phosphorylated in HCV-infected cells, and this phosphorylation is also reduced by the knockdown of c-Abl. Mutational analysis reveals that NS5A tyrosine phosphorylation is dependent, at least in part, on Tyr(330) (Tyr(2306) in polyprotein numbering). Mutation of this residue to phenylalanine reduces the production of infectious HCV particles but does not affect the replication of the JFH1 subgenomic replicon. These findings suggest that c-Abl promotes HCV particle assembly by phosphorylating NS5A at Tyr(330)., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2015
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- View/download PDF
235. Metal-organic framework tethering PNIPAM for ON-OFF controlled release in solution.
- Author
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Nagata S, Kokado K, and Sada K
- Abstract
A smart metal-organic framework (MOF) exhibiting controlled release was achieved by modification with a thermoresponsive polymer (PNIPAM) via a surface-selective post-synthetic modification technique. Simple temperature variation readily switches "open" (lower temperature) and "closed" (higher temperature) states of the polymer-modified MOF through conformational change of PNIPAM grafted onto the MOF, resulting in controlled release of the included guest molecules such as resorufin, caffeine, and procainamide.
- Published
- 2015
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- View/download PDF
236. Mentoring the next generation of physician-scientists in Japan: a cross-sectional survey of mentees in six academic medical centers.
- Author
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Sakushima K, Mishina H, Fukuhara S, Sada K, Koizumi J, Sugioka T, Kobayashi N, Nishimura M, Mori J, Makino H, and Feldman MD
- Subjects
- Adult, Cross-Sectional Studies, Education, Medical, Continuing methods, Faculty, Medical, Female, Humans, Interprofessional Relations, Japan, Male, Academic Medical Centers organization & administration, Clinical Competence, Mentors, Translational Research, Biomedical education
- Abstract
Background: Physician-scientists play key roles in biomedical research across the globe, yet prior studies have found that it is increasingly difficult to recruit and retain physician-scientists in research careers. Access to quality research mentorship may help to ameliorate this problem in the U.S., but there is virtually no information on mentoring in academic medicine in Japan. We conducted a survey to determine the availability and quality of mentoring relationships for trainee physician-scientists in Japan., Methods: We surveyed 1700 physician-scientists in post-graduate research training programs in 6 academic medical centers in Japan about mentorship characteristics, mentee perceptions of the mentoring relationship, and attitudes about career development., Results: A total of 683 potential physician-scientist mentees completed the survey. Most reported that they had a departmental mentor (91%) with whom they met at least once a month; 48% reported that they were very satisfied with the mentoring available to them. Mentoring pairs were usually initiated by the mentor (85% of the time); respondents identified translational research skills (55%) and grant writing (50%) as unmet needs. Mentoring concerning long-term career planning was significantly associated with the intention to pursue research careers, however this was also identified by some mentees as an unmet need (35% desired assistance; 15% reported receiving it)., Conclusions: More emphasis and formal training in career mentorship may help to support Japanese physician-scientist mentees to develop a sense of self-efficacy to pursue and stay in research careers.
- Published
- 2015
- Full Text
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237. Effect of length and rigidity of microtubules on the size of ring-shaped assemblies obtained through active self-organization.
- Author
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Wada S, Kabir AM, Ito M, Inoue D, Sada K, and Kakugo A
- Subjects
- Animals, Biomimetics, Guanosine Triphosphate analogs & derivatives, Guanosine Triphosphate metabolism, Kinesins metabolism, Microscopy, Fluorescence, Swine, Microtubules metabolism
- Abstract
The microtubule (MT)-kinesin biomolecular motor system has attracted considerable attention due to its possible applications in artificial biomachines. Recently, an active self-organization (AcSO) method has been established to integrate MT filaments into highly organized assembled structures. The ring-shaped MT assembly, one of the structures derived from the AcSO of MTs, can convert the translational motion of MTs into rotational motion. Due to this attractive feature, the ring-shaped MT assembly appears to be a promising candidate for developing artificial devices and for future nanotechnological applications. In this work, we have investigated the effect of length and rigidity of the MT filaments on the size of the ring-shaped MT assembly in the AcSO process. We show that the size of the ring-shaped MT assembly can be controlled by tuning the length and rigidity of MT filaments employed in the AcSO. Longer and stiffer MT filaments led to larger ring-shaped assemblies through AcSO, whereas AcSO of shorter and less stiff MT filaments produced smaller ring-shaped assemblies. This work might be important for the development of biomolecular motor based artificial biomachines, especially where size control of ring-shaped MT assembly will play an important role.
- Published
- 2015
- Full Text
- View/download PDF
238. Controlling the bias of rotational motion of ring-shaped microtubule assembly.
- Author
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Wada S, Kabir AM, Kawamura R, Ito M, Inoue D, Sada K, and Kakugo A
- Subjects
- Animals, Biomechanical Phenomena, Biotin chemistry, Humans, Kinesins metabolism, Recombinant Proteins chemistry, Recombinant Proteins metabolism, Rotation, Swine, Tubulin metabolism, Kinesins chemistry, Tubulin chemistry
- Abstract
Biomolecular motor system microtubule (MT)-kinesin is considered a building block for developing artificial microdevices. Recently, an active self-organization method has been established to integrate MT filaments into ring-shaped assembly that can produce rotational motion both in the clockwise and in the counterclockwise directions. In this work, we have investigated the effect of parameters such as MT and kinesin concentration, length, and rigidity of MT and type of kinesin (structure of tail region) on the preferential rotation of the ring-shaped MT assembly produced in an active self-organization. We elucidated that these factors can significantly affect the bias of rotation of the ring-shaped MT assembly, which seems to be related to the fluctuation of leading tip of moving MT filaments. This new finding might be important for designing handedness regulated artificial biomachine using the ring-shaped MT assembly in future.
- Published
- 2015
- Full Text
- View/download PDF
239. Surveillance for the use of mycophenolate mofetil for adult patients with lupus nephritis in Japan.
- Author
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Yasuda S, Atsumi T, Shimamura S, Ono K, Hiromura K, Sada K, Mori M, Takei S, Kawaguchi Y, Tamura N, and Takasaki Y
- Subjects
- Adult, Aged, Female, Humans, Immunosuppressive Agents administration & dosage, Immunosuppressive Agents adverse effects, Japan, Male, Middle Aged, Mycophenolic Acid administration & dosage, Mycophenolic Acid adverse effects, Mycophenolic Acid therapeutic use, Remission Induction, Retrospective Studies, Rheumatology, Treatment Outcome, Immunosuppressive Agents therapeutic use, Lupus Nephritis drug therapy, Mycophenolic Acid analogs & derivatives, Off-Label Use
- Abstract
Objectives: Mycophenolate mofetil (MMF) is used as one of the standard induction/maintenance protocols for lupus nephritis (LN). However, MMF has not been approved for treating LN in any country, resulting in worldwide off-label use of this immunosuppressant. In order to clarify the real-world use of MMF as a treatment for LN in Japan, Japan College of Rheumatology surveyed the use of MMF in daily clinical practice., Methods: Adult patients with LN who visited enrolled hospitals from October 2008 to September 2013 were surveyed for the initial, maximum, and maintenance doses of MMF. The safety and efficacy of MMF were retrospectively evaluated., Results: One hundred and thirty-seven LN patients including 116 females were enrolled. The median of initial, maximum, and maintenance doses of MMF were 1.0 g/day, 1.5 g/day, and 1.0 g/day, respectively. Sixty-one adverse events were reported in 39 patients during the follow-up period. Median urine protein level decreased from 1.89 g/gCr to 0.21 g/gCr, meanC3 level increased from 66.4 mg/dl to 80.3 mg/dl, and median anti-DNA antibody titer decreased from 40.6 IU/ml to 10.6 IU/ml., Conclusion: MMF was commonly used for the treatment of adult LN patients with acceptable efficacy and safety in Japan.
- Published
- 2015
- Full Text
- View/download PDF
240. Dectin-1-mediated signaling leads to characteristic gene expressions and cytokine secretion via spleen tyrosine kinase (Syk) in rat mast cells.
- Author
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Kimura Y, Chihara K, Honjoh C, Takeuchi K, Yamauchi S, Yoshiki H, Fujieda S, and Sada K
- Subjects
- Animals, Antifungal Agents chemistry, Cell Line, Tumor, Dendritic Cells metabolism, Dendritic Cells microbiology, Immunity, Innate, Macrophages metabolism, Macrophages microbiology, Mast Cells cytology, Mice, Mycoses immunology, Phosphorylation, Rats, Signal Transduction, Syk Kinase, Tyrosine chemistry, beta-Glucans chemistry, beta-Glucans metabolism, Cytokines metabolism, Gene Expression Profiling, Gene Expression Regulation, Enzymologic, Intracellular Signaling Peptides and Proteins metabolism, Lectins, C-Type metabolism, Mast Cells enzymology, Protein-Tyrosine Kinases metabolism
- Abstract
Dectin-1 recognizes β-glucan and plays important roles for the antifungal immunity through the activation of spleen tyrosine kinase (Syk) in dendritic cells or macrophages. Recently, expression of Dectin-1 was also identified in human and mouse mast cells, although its physiological roles were largely unknown. In this report, rat mast cell line RBL-2H3 was analyzed to investigate the molecular mechanism of Dectin-1-mediated activation and responses of mast cells. Treatment of cells with Dectin-1-specific agonist curdlan induced tyrosine phosphorylation of cellular proteins and the interaction of Dectin-1 with the Src homology 2 domain of Syk. These responses depended on tyrosine phosphorylation of the hemi-immunoreceptor tyrosine-based activation motif in the cytoplasmic tail of Dectin-1, whereas they were independent of the γ-subunit of high-affinity IgE receptor. DNA microarray and real-time PCR analyses showed that Dectin-1-mediated signaling stimulated gene expression of transcription factor Nfkbiz and inflammatory cytokines, such as monocyte chemoattractant protein-1, IL-3, IL-4, IL-13, and tumor necrosis factor (TNF)-α. The response was abrogated by pretreatment with Syk inhibitor R406. These results suggest that Syk is critical for Dectin-1-mediated activation of mast cells, although the signaling differs from that triggered by FcϵRI activation. In addition, these gene expressions induced by curdlan stimulation were specifically observed in mast cells, suggesting that Dectin-1-mediated signaling of mast cells offers new insight into the antifungal immunity., (© 2014 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2014
- Full Text
- View/download PDF
241. Biomolecular motor modulates mechanical property of microtubule.
- Author
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Kabir AM, Inoue D, Hamano Y, Mayama H, Sada K, and Kakugo A
- Subjects
- Animals, Kinesins chemistry, Kinesins isolation & purification, Surface Properties, Swine, Tubulin chemistry, Tubulin isolation & purification, Tubulin metabolism, Kinesins metabolism, Microtubules chemistry, Microtubules metabolism
- Abstract
The microtubule (MT) is the stiffest cytoskeletal filamentous protein that takes part in a wide range of cellular activities where its mechanical property plays a crucially significant role. How a single biological entity plays multiple roles in cell has been a mystery for long time. Over the recent years, it has been known that modulation of the mechanical property of MT by different cellular agents is the key to performing manifold in vivo activities by MT. Studying the mechanical property of MT thus has been a prerequisite in understanding how MT plays such diversified in vivo roles. However, the anisotropic structure of MT has been an impediment in obtaining a precise description of the mechanical property of MT along its longitudinal and lateral directions that requires employment of distinct experimental approach and has not been demonstrated yet. In this work, we have developed an experimental system that enabled us to investigate the effect of tensile stress on MT. By using our newly developed system, (1) we have determined the Young's modulus of MT considering its deformation under applied tensile stress and (2) a new role of MT associated motor protein kinesin in modulating the mechanical property of MT was revealed for the first time. Decrease in Young's modulus of MT with the increase in interaction with kinesin suggests that kinesin has a softening effect on MT and thereby can modulate the rigidity of MT. This work will be an aid in understanding the modulation of mechanical property of MTs by MT associated proteins and might also help obtain a clear insight of the endurance and mechanical instability of MTs under applied stress.
- Published
- 2014
- Full Text
- View/download PDF
242. Tyrosine phosphorylation of 3BP2 is indispensable for the interaction with VAV3 in chicken DT40 cells.
- Author
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Chihara K, Kimura Y, Honjoh C, Yamauchi S, Takeuchi K, and Sada K
- Subjects
- Adaptor Proteins, Signal Transducing chemistry, Animals, COS Cells, Cell Line, Chickens, Chlorocebus aethiops, Intracellular Signaling Peptides and Proteins metabolism, Phosphorylation physiology, Protein Binding, Proto-Oncogene Proteins c-bcr metabolism, Syk Kinase, src Homology Domains, Adaptor Proteins, Signal Transducing metabolism, Protein Processing, Post-Translational physiology, Protein-Tyrosine Kinases metabolism, Proto-Oncogene Proteins c-vav metabolism
- Abstract
Adaptor protein c-Abl SH3 domain-binding protein-2 (3BP2) is known to play regulatory roles in immunoreceptor-mediated signal transduction. We have previously demonstrated that Tyr(174), Tyr(183) and Tyr(446) in mouse 3BP2 are predominantly phosphorylated by Syk, and the phosphorylation of Tyr(183) and the Src homology 2 (SH2) domain of mouse 3BP2 are critical for B cell receptor (BCR)-induced activation of nuclear factor of activated T cells (NFAT) in human B cells. In this report, we have shown that Syk, but not Abl family protein-tyrosine kinases, is critical for BCR-mediated tyrosine phosphorylation of 3BP2 in chicken DT40 cells. Mutational analysis showed that Tyr(174), Tyr(183) and Tyr(426) of chicken 3BP2 are the major phosphorylation sites by Syk and the SH2 domain of 3BP2 is critical for tyrosine phosphorylation. In addition, phosphorylation of Tyr(426) is required for the inducible interaction with the SH2 domain of Vav3. Moreover, the expression of the mutant form of 3BP2 in which Tyr(426) was substituted to Phe resulted in the reduction in BCR-mediated Rac1 activation, when compared with the case of wild-type. Altogether, these data suggest that 3BP2 is involved in the activation of Rac1 through the regulation of Vav3 by Syk-dependent phosphorylation of Tyr(426) following BCR stimulation., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
243. [Syk inhibitors].
- Author
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Kimura Y, Chihara K, Takeuchi K, and Sada K
- Subjects
- Adaptor Proteins, Signal Transducing immunology, Adaptor Proteins, Signal Transducing metabolism, Humans, Intracellular Signaling Peptides and Proteins chemistry, Protein-Tyrosine Kinases chemistry, Signal Transduction drug effects, Syk Kinase, Antirheumatic Agents therapeutic use, Arthritis, Rheumatoid drug therapy, Intracellular Signaling Peptides and Proteins antagonists & inhibitors, Protein Kinase Inhibitors therapeutic use, Protein-Tyrosine Kinases antagonists & inhibitors
- Abstract
Non-receptor type of protein-tyrosine kinase Syk (spleen tyrosine kinase) was isolated in the University of Fukui in 1991. Syk is known to be essential for the various physiological functions, especially in hematopoietic lineage cells. Moreover, ectopic expression of Syk by epigenetic changes is reported to cause retinoblastoma. Recently, novel Syk inhibitors were developed and its usefulness has been evaluated in the treatment of allergic rhinitis, rheumatoid arthritis, and idiopathic thrombocytopenic purpura. In this review, we will summarize the history, structure, and function of Syk, and then describe the novel Syk inhibitors and their current status. Furthermore, we will introduce our findings of the adaptor protein 3BP2 (c-Abl SH3 domain-binding protein-2), as a novel target of Syk.
- Published
- 2013
244. Transformation of metal-organic framework to polymer gel by cross-linking the organic ligands preorganized in metal-organic framework.
- Author
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Ishiwata T, Furukawa Y, Sugikawa K, Kokado K, and Sada K
- Subjects
- Cross-Linking Reagents chemistry, Ligands, Molecular Structure, Organometallic Compounds chemistry, Particle Size, Surface Properties, Cross-Linking Reagents chemical synthesis, Gels chemistry, Organometallic Compounds chemical synthesis, Polymers chemistry
- Abstract
Until now, seamless fusion of metal-organic frameworks (MOFs) and covalently cross-linked polymer gels (PG) at molecular level has been extremely rare, since these two matters have been regarded as opposite, that is, hard versus soft. In this report, we demonstrate transformation of cubic MOF crystals to PG via inner cross-linking of the organic linkers in the void space of MOF, followed by decomposition of the metal coordination. The obtained PG behaved as a polyelectrolyte gel, indicating the high content of ionic groups inside. Metal ions were well adsorbed in the PG due to its densely packed carboxylate groups. A chimera-type hybrid material consisting of MOF and PG was obtained by partial hydrolysis of resulting cross-linked MOF. The shape of resulting PG network well reflected the crystal structure of MOF employed as a template. Our results will connect the two different network materials that have been ever studied in the two different fields to provide new soft and hard hybrid materials, and the unique copolymerization in the large void space of the MOF will open a new horizon toward "ideal network polymers" never prepared before now.
- Published
- 2013
- Full Text
- View/download PDF
245. Polymer phase-transition behavior driven by a charge-transfer interaction.
- Author
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Amemori S, Kokado K, and Sada K
- Subjects
- Molecular Structure, Phase Transition, Solubility, Temperature, Polymers chemistry
- Published
- 2013
- Full Text
- View/download PDF
246. Syk inhibitors.
- Author
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Chihara K, Kimura Y, Honjo C, Takeuchi K, and Sada K
- Subjects
- Aminopyridines, Humans, Intracellular Signaling Peptides and Proteins physiology, Mast Cells enzymology, Morpholines, Oxazines therapeutic use, Protein-Tyrosine Kinases physiology, Pyridines therapeutic use, Pyrimidines, Syk Kinase, Intracellular Signaling Peptides and Proteins antagonists & inhibitors, Protein-Tyrosine Kinases antagonists & inhibitors
- Abstract
Non-receptor type of protein-tyrosine kinase Syk (spleen tyrosine kinase) was isolated in University of Fukui in 1991. Syk is most highly expressed by haemopoietic cells and known to play crucial roles in the signal transduction through various immunoreceptors of the adaptive immune response. However, recent reports demonstrate that Syk also mediates other biological functions, such as innate immune response, osteoclast maturation, platelet activation and cellular adhesion. Moreover, ectopic expression of Syk by epigenetic changes is reported to cause retinoblastoma. Because of its critical roles on the cellular functions, the development of Syk inhibitors for clinical use has been desired. Although many candidate compounds were produced, none of them had progressed to clinical trials. However, novel Syk inhibitors were finally developed and its usefulness has been evaluated in the treatment of allergic rhinitis, rheumatoid arthritis and idiopathic thrombocytopenic purpura. In this review, we will summarize the history, structure and function of Syk, and then the novel Syk inhibitors and their current status. In addition, we will introduce our research focused on the functions of Syk on Dectin-1-mediated mast cell activation.
- Published
- 2013
- Full Text
- View/download PDF
247. Ionic Polymers Act as Polyelectrolytes in Nonpolar Media.
- Author
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Ono T, Ohta M, and Sada K
- Abstract
Polyelectrolytes are ubiquitous materials, and their unique properties originate from dissociation of ionic groups to the small number of macromolecular ions and the large number of small counterions. They have been exploited only in water or high-dielectric media and scarcely in nonpolar ones (ε < 10). Herein, we demonstrate that poly(octadecyl acrylate) bearing tetraalkylammonium tetraarylborate as ionic groups behaves as a polyelectrolyte in the common nonpolar organic solvents such as chloroform, THF, and 1,2-dichloroethane. Conductivity measurement, DOSY NMR spectroscopy, and viscosity measurements clearly indicate that they form the extended conformation in them. This result emphasizes that the ionic polymers bearing suitable ion pairs ionizable in the given media act as polyelectrolytes. Various characteristic properties and processes of polyelectrolytes should be realized in nonpolar media by designing ion pairs and polymer chains in the ionic polymers. Moreover, our results imply that electrostatic interaction is readily available as a long-range repulsive force even in the nonpolar media.
- Published
- 2012
- Full Text
- View/download PDF
248. Nano- and microsized cubic gel particles from cyclodextrin metal-organic frameworks.
- Author
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Furukawa Y, Ishiwata T, Sugikawa K, Kokado K, and Sada K
- Subjects
- Models, Molecular, Molecular Conformation, Particle Size, Porosity, Cyclodextrins chemistry, Gels chemistry, Metals chemistry, Nanoparticles chemistry, Organometallic Compounds chemistry
- Abstract
Sweet cube o' mine: Bottom-up control of gel particles has been regarded as a great challenge. By employing internal cross-linking of cyclodextrin metal-organic frameworks, cubic sugar gels were formed with sharp edges that reflect the shape of the crystals. This enabled the fabrication of shape- and size-controlled polymer gels from porous crystals (see picture)., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2012
- Full Text
- View/download PDF
249. [Trends in drug development for diabetic retinopathy].
- Author
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Nishikawa T, Goto H, Sada K, Kukidome D, and Araki E
- Subjects
- Animals, Diabetic Retinopathy metabolism, Glycation End Products, Advanced metabolism, Humans, Oxidative Stress drug effects, Polymers, Protein Kinase C metabolism, Diabetic Retinopathy drug therapy
- Published
- 2012
250. Fundamental molecular design for precise control of thermoresponsiveness of organic polymers by using ternary systems.
- Author
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Amemori S, Kokado K, and Sada K
- Abstract
The de novo design of thermosensitive polymers in solution has been achieved by using the addition of small organic molecules (or "effectors"). Hydrogen bonding as an attractive polymer-polymer or polymer-effector interaction substantially dominates the responsivity, causing facile switching between LCST-type and UCST-type phase transitions, control of the transition temperature, and further coincidence of the two transitions. Small molecules having a high affinity for the polymer induce UCST-type phase behavior, whereas those having a low affinity for the polymer showed LCST-type phase behavior.
- Published
- 2012
- Full Text
- View/download PDF
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