1,346 results on '"A, Umemoto"'
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2. Development of Water Solubility of 2‑Phenylsulfanylhydroquinone Dimer Dye
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Akio Kamimura, Haruka Umemoto, Takuji Kawamoto, and Takeshi Honda
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Chemistry ,QD1-999 - Published
- 2021
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3. Ionization of Xenon Clusters by a Hard X-ray Laser Pulse
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Yoshiaki Kumagai, Weiqing Xu, Kazuki Asa, Toshiyuki Hiraki Nishiyama, Koji Motomura, Shin-ichi Wada, Denys Iablonskyi, Subhendu Mondal, Tetsuya Tachibana, Yuta Ito, Tsukasa Sakai, Kenji Matsunami, Takayuki Umemoto, Christophe Nicolas, Catalin Miron, Tadashi Togashi, Kanade Ogawa, Shigeki Owada, Kensuke Tono, Makina Yabashi, Hironobu Fukuzawa, Kiyonobu Nagaya, and Kiyoshi Ueda
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hard X-ray laser ,xenon cluster ,nanoplasma ,electron spectroscopy ,ion time-of-flight spectroscopy ,pump–probe experiment ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Ultrashort pulse X-ray free electron lasers (XFFLs) provided us with an unprecedented regime of X-ray intensities, revolutionizing ultrafast structure determination and paving the way to the novel field of non-linear X-ray optics. While pioneering studies revealed the formation of a nanoplasma following the interaction of an XFEL pulse with nanometer-scale matter, nanoplasma formation and disintegration processes are not completely understood, and the behavior of trapped electrons in the electrostatic potential of highly charged species is yet to be decrypted. Here we report the behavior of the nanoplasma created by a hard X-ray pulse interacting with xenon clusters by using electron and ion spectroscopy. To obtain a deep insight into the formation and disintegration of XFEL-ignited nanoplasma, we studied the XFEL-intensity and cluster-size dependencies of the ionization dynamics. We also present the time-resolved data obtained by a near-infrared (NIR) probe pulse in order to experimentally track the time evolution of plasma electrons distributed in the XFEL-ignited nanoplasma. We observed an unexpected time delay dependence of the ion yield enhancement due to the NIR pulse heating, which demonstrates that the plasma electrons within the XFEL-ignited nanoplasma are inhomogeneously distributed in space.
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- 2023
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4. Self-Organizing Super-Structures Formed from Hydrogen-Bonded Biimidazolate Metal Complexes
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Tadokoro, Makoto, Kanno, Hideaki, Kitajima, Tadanori, Shimada-Umemoto, Hiromi, Nakanishi, Noritaka, Isobe, Kiyoshi, and Nakasuji, Kazuhiro
- Published
- 2002
5. Mechanical Properties of Cementite
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Hideyuki Ohtsuka and Minoru Umemoto
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chemistry.chemical_compound ,Materials science ,chemistry ,Cementite ,Mechanics of Materials ,Mechanical Engineering ,Metallurgy ,Materials Chemistry ,Metals and Alloys ,Physical and Theoretical Chemistry ,Condensed Matter Physics - Published
- 2022
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6. In vivo bioresorbability and bone formation ability of sintered highly pure calcium carbonate granules
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Toshitake Furusawa, Shota Umemoto, Tohru Sekino, Masahiko Tajika, and Hidero Unuma
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Calcite ,Materials science ,Aragonite ,technology, industry, and agriculture ,chemistry.chemical_element ,Sintering ,Calcium ,engineering.material ,equipment and supplies ,Phosphate ,Resorption ,chemistry.chemical_compound ,Calcium carbonate ,chemistry ,Chemical engineering ,In vivo ,Ceramics and Composites ,engineering ,General Dentistry - Abstract
Calcium carbonate-based bone substitutes derived from natural coral exoskeleton (aragonite) are resorbed and remodeled faster than calcium phosphate-based substitutes. However, coral species with structures appropriate for use as bone substitutes are very limited. Therefore, it is important to evaluate potential of artificial calcium carbonate ceramics as a bone substitute. In this study, calcium carbonate granules with various porosities and pore sizes were prepared by sintering a highly pure (>99.98%) calcium carbonate powder (calcite), and their resorption properties and bone formation abilities were examined in vivo for the first time. The sintered calcium carbonate was resorbed faster than β-tricalcium phosphate, which has a similar structure. However, sintered calcium carbonate did not promote new bone formation during long-term implantation. Furthermore, both resorption and new bone formation were affected by the pore structure. The optimal structures of the artificially sintered calcium carbonate bone substitute were also discussed.
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- 2021
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7. Gummi Formulations Comprising Amenamevir Solid Dispersions with Polyvinyl Alcohol
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Shinya Uchida, Atsushi Kambayashi, Koki Sugimoto, Noriyuki Namiki, Yoshiaki Umemoto, Yasuharu Kashiwagura, and Shimako Tanaka
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Oxadiazoles ,food.ingredient ,Molecular Structure ,Drug Compounding ,Water ,In vivo absorption ,General Chemistry ,General Medicine ,Polyvinyl alcohol ,Gelatin ,chemistry.chemical_compound ,food ,Sensory tests ,chemistry ,Polyvinyl Alcohol ,Drug Discovery ,Absorption (chemistry) ,Dissolution ,Nuclear chemistry - Abstract
The aim of the present study was to determine whether solid dispersions (SDs) are applicable to gummi formulations. Amenamevir was selected as a model of a poorly water-soluble drug, and polyvinyl alcohols (PVAs) with various degrees of hydrolysis (PVA 66, PVA 80, PVA 88, and PVA 66/88) were used as SD carriers. Design of experiments (DOE) was used to develop a gummi formulation that was suitable for an amenamevir SD using SD with PVA 66. Dissolution studies and clinical sensory tests on 11 formulations calculated by DOE revealed that a gummi formulation comprising 10.5% gelatin and 22.8% water was suitable for SD of the drug. Gummi formulations comprising amenamevir SDs with various PVAs were prepared using the determined gummi formulation, and their ability to dissolve amenamevir, their stability, and their oral absorption in dogs were evaluated. The results suggested that PVA 66, PVA 66/88, and PVA 80 were appropriate in terms of dissolution, stability, and in vivo absorption, respectively. Considering these results comprehensively, it was concluded that PVA 80, which enabled the highest degree of absorption, was the most suitable SD carrier for gummi formulations. Thus, it was possible to apply a PVA SD of amenamevir to gummi formulations.
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- 2021
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8. Characterization of C‐26 aminotransferase, indispensable for steroidal glycoalkaloid biosynthesis
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Haruka Miyachi, Bunta Watanabe, Masaharu Mizutani, Naoyuki Umemoto, Toshiya Muranaka, Kazuki Saito, Masaru Nakayasu, Ryota Akiyama, Kiyoshi Ohyama, Hyoung Jae Lee, and Yukihiro Sugimoto
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Transamination ,Plant Science ,Hydroxylation ,chemistry.chemical_compound ,Glycoalkaloid ,Biosynthesis ,Genetics ,Ketocholesterols ,Plant Proteins ,Solanum tuberosum ,Gene Editing ,chemistry.chemical_classification ,biology ,fungi ,food and beverages ,Cytochrome P450 ,Cell Biology ,Saponins ,Monooxygenase ,biology.organism_classification ,Solanine ,Complementation ,Plant Tubers ,chemistry ,Biochemistry ,4-Aminobutyrate Transaminase ,biology.protein ,Solanum - Abstract
Steroidal glycoalkaloids (SGAs) are toxic specialized metabolites found in members of the Solanaceae, such as Solanum tuberosum (potato) and Solanum lycopersicum (tomato). The major potato SGAs are α-solanine and α-chaconine, which are biosynthesized from cholesterol. Previously, we have characterized two cytochrome P450 monooxygenases and a 2-oxoglutarate-dependent dioxygenase that function in hydroxylation at the C-22, C-26 and C-16α positions, but the aminotransferase responsible for the introduction of a nitrogen moiety into the steroidal skeleton remains uncharacterized. Here, we show that PGA4 encoding a putative γ-aminobutyrate aminotransferase is involved in SGA biosynthesis in potatoes. The PGA4 transcript was expressed at high levels in tuber sprouts, in which SGAs are abundant. Silencing the PGA4 gene decreased potato SGA levels and instead caused the accumulation of furostanol saponins. Analysis of the tomato PGA4 ortholog, GAME12, essentially provided the same results. Recombinant PGA4 protein exhibited catalysis of transamination at the C-26 position of 22-hydroxy-26-oxocholesterol using γ-aminobutyric acid as an amino donor. Solanum stipuloideum (PI 498120), a tuber-bearing wild potato species lacking SGA, was found to have a defective PGA4 gene expressing the truncated transcripts, and transformation of PI 498120 with functional PGA4 resulted in the complementation of SGA production. These findings indicate that PGA4 is a key enzyme for transamination in SGA biosynthesis. The disruption of PGA4 function by genome editing will be a viable approach for accumulating valuable steroidal saponins in SGA-free potatoes.
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- 2021
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9. Development of N-F fluorinating agents and their fluorinations: Historical perspective
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Yuhao Yang, Teruo Umemoto, and Gerald B. Hammond
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chemistry.chemical_classification ,010405 organic chemistry ,Research areas ,Chemistry ,fluorosulfonimide ,Science ,Organic Chemistry ,chemistry.chemical_element ,Salt (chemistry) ,DABCO ,Optically active ,fluoropyridinium salt ,010402 general chemistry ,01 natural sciences ,fluorination ,0104 chemical sciences ,fluorodiazoniabicyclo[2.2.2]octane salt ,chemistry.chemical_compound ,QD241-441 ,n-f fluorinating agent ,Reagent ,Fluorine ,Organic chemistry ,Octane - Abstract
This review deals with the historical development of all N-F fluorinating agents developed so far. The unique properties of fluorine make fluorinated organic compounds attractive in many research areas and therefore fluorinating agents are important. N-F agents have proven useful by virtue of their easy handling. This reagent class includes many types of N-F compounds: perfluoro-N-fluoropiperidine, N-fluoro-2-pyridone, N-fluoro-N-alkylarenesulfonamides, N-fluoropyridinium salts and derivatives, N-fluoroquinuclidium salts, N-fluoro-trifluoromethanesulfonimide, N-fluoro-sultams, N-fluoro-benzothiazole dioxides, N-fluoro-lactams, N-fluoro-o-benzenedisulfonimide, N-fluoro-benzenesulfonimide, 1-alkyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluoropyridinium-2-sulfonate derivatives, 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluorodinitroimidazole, N-fluoro-trichloro-1,3,5-triazinium salt, N-F ethano-Tröger’s base derivatives, N-fluoro-methanesulfonimide, N-fluoro-N-arylarenesulfonamides, bisN-F salts such as N,N’-difluorobipyridinium salts and N,N’-difluoro-1,4-diazoniabicyclo[2.2.2]octane salts, and their many derivatives and analogs, including chiral N-F reagents such as optically active N-fluoro-sultam derivatives, N-fluoro-alkaloid derivatives, DABCO-based N-F derivatives, and N-F binaphthyldisulfonimides. The synthesis and reactions of these reagents are described chronologically and the review also discusses the relative fluorination power of each reagent and their mechanisms chronicling developments from a historical perspective.
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- 2021
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10. Trifluoromethyl Nonaflate: A Practical Trifluoromethoxylating Reagent and its Application to the Regio‐ and Stereoselective Synthesis of Trifluoromethoxylated Alkenes
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Teruo Umemoto, Zhichao Lu, Tatsuya Kumon, and Gerald B. Hammond
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chemistry.chemical_classification ,Primary (chemistry) ,Trifluoromethyl ,Hydrocarbons, Fluorinated ,Alkyne ,Stereoisomerism ,General Medicine ,Chemistry Techniques, Synthetic ,General Chemistry ,Alkenes ,Combinatorial chemistry ,Article ,Catalysis ,chemistry.chemical_compound ,chemistry ,Nucleophile ,Reagent ,Stereoselectivity ,Indicators and Reagents ,Nonaflate ,Alkyl - Abstract
The trifluoromethoxy group has elicited much interest among drug and agrochemical discovery teams because of its unique properties. We developed trifluoromethyl nonafluorobutanesulfonate (nonaflate), TFNf, an easy-to-handle, bench-stable, reactive, and scalable trifluoromethoxylating reagent. TFNf is easily and safely prepared in a simple process in large scale and the nonaflyl part of TFNf can easily be recovered as nonaflyl fluoride after usage and recycled. The synthetic potency of TFNf was showcased with the underexplored synthesis of various trifluoromethoxylated alkenes, through a high regio- and stereoselective hydro(halo)trifluoromethoxylation of alkyne derivatives such as haloalkynes, alkynyl esters, and alkynyl sulfones. The synthetic merits of TFNf were further underscored with a high-yielding and smooth nucleophilic trifluoromethoxylation of alkyl triflates/bromides and primary/secondary alcohols.
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- 2021
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11. Removal of Novolac Photoresist with Various Concentrations of Photo-active Compound Using H2/O2 Mixtures Activated on a Tungsten Hot-wire Catalyst
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Masashi Yamamoto, Shota Sogo, Koki Akita, Hideo Horibe, Ryusei Sogame, Shiro Nagaoka, and Hironobu Umemoto
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Materials science ,Polymers and Plastics ,Chemical engineering ,chemistry ,Active compound ,Organic Chemistry ,Materials Chemistry ,chemistry.chemical_element ,Photoresist ,Tungsten ,Catalysis - Published
- 2021
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12. Molecular Dynamics Simulation of Fracture at a Polymer and Metal Oxide Joining Interface
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Kazuhiko Umemoto, Hiroaki Yoneyama, and Tomoyuki Kinjo
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chemistry.chemical_classification ,Sulfide ,010405 organic chemistry ,Chemistry ,Oxide ,General Chemistry ,Polymer ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Metal ,Molecular dynamics ,chemistry.chemical_compound ,visual_art ,Fracture (geology) ,visual_art.visual_art_medium ,Composite material ,Layer (electronics) - Abstract
Molecular dynamics simulations are used to study the fracture mechanism of the joining interface of a polymer and metal oxide. A polyphenylene sulfide (PPS) layer is sandwiched between two plates o...
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- 2021
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13. Multispectroscopic Study of Single Xe Clusters Using XFEL Pulses
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Toshiyuki Nishiyama, Christoph Bostedt, Ken R. Ferguson, Christopher Hutchison, Kiyonobu Nagaya, Hironobu Fukuzawa, Koji Motomura, Shin-ichi Wada, Tsukasa Sakai, Kenji Matsunami, Kazuhiro Matsuda, Tetsuya Tachibana, Yuta Ito, Weiqing Xu, Subhendu Mondal, Takayuki Umemoto, Catalin Miron, Christophe Nicolas, Takashi Kameshima, Yasumasa Joti, Kensuke Tono, Takaki Hatsui, Makina Yabashi, and Kiyoshi Ueda
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xfel ,diffractive imaging ,fluorescence spectroscopy ,ion spectroscopy ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
X-ray free-electron lasers (XFELs) deliver ultrashort coherent laser pulses in the X-ray spectral regime, enabling novel investigations into the structure of individual nanoscale samples. In this work, we demonstrate how single-shot small-angle X-ray scattering (SAXS) measurements combined with fluorescence and ion time-of-flight (TOF) spectroscopy can be used to obtain size- and structure-selective evaluation of the light-matter interaction processes on the nanoscale. We recorded the SAXS images of single xenon clusters using XFEL pulses provided by the SPring-8 Angstrom compact free-electron laser (SACLA). The XFEL fluences and the radii of the clusters at the reaction point were evaluated and the ion TOF spectra and fluorescence spectra were sorted accordingly. We found that the XFEL fluence and cluster size extracted from the diffraction patterns showed a clear correlation with the fluorescence and ion TOF spectra. Our results demonstrate the effectiveness of the multispectroscopic approach for exploring laser−matter interaction in the X-ray regime without the influence of the size distribution of samples and the fluence distribution of the incident XFEL pulses.
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- 2019
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14. Development of Water Solubility of 2-Phenylsulfanylhydroquinone Dimer Dye
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Takeshi Honda, Haruka Umemoto, Takuji Kawamoto, and Akio Kamimura
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Aqueous solution ,biology ,General Chemical Engineering ,Bioactive molecules ,Dimer ,Light irradiation ,General Chemistry ,Combinatorial chemistry ,Fluorescence ,Article ,Chemistry ,chemistry.chemical_compound ,chemistry ,biology.protein ,Side chain ,Molecule ,Bovine serum albumin ,QD1-999 - Abstract
With the aim of developing a new fluorescence dye with enhanced photophysical properties, this study describes the modification of the 2-phenylsulfanylhydroquinone dimer to realize a new bioimaging molecule. The characteristics of the dimer were advanced by introducing tetraethylene glycol side chains to provide sufficient water solubility and a tether consisting of an N-hydroxysuccinimide-terminated C6-carbon chain to attach bioactive molecules. Two derivatives containing two or three tetraethylene glycol side chains were designed and prepared, and the latter showed sufficient water solubility for biochemical applications. Both compounds exhibited similar photophysical properties and blue fluorescence under UV light irradiation. The dye containing three tetraethylene glycol units reacted with bovine serum albumin in water to give fluorescent derivatives.
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- 2021
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15. Murine neonatal ketogenesis preserves mitochondrial energetics by preventing protein hyperacetylation
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Yumiko Kawamura, Yasuhiro Izumiya, Mitsuyoshi Nakao, Yasuhito Tanaka, Yoshifumi Sato, Kazuya Yamagata, Toshihiro Yamada, Kazuo Tonami, Takashi Yamamoto, Terumasa Umemoto, Naomi Nakagata, Toru Takeo, Shinjiro Hino, Kenichi Matsushita, Yoshiko Nakagawa, Toshio Suda, Sanshiro Hanada, Taishi Nakamura, Kenji Sakamoto, Takehisa Watanabe, Yuichiro Arima, Katsuya Nagaoka, Eiichiro Yamamoto, Hiroki Kurihara, Koichi Nishiyama, Koichi Kaikita, Kenichi Tsujita, Tetsushi Sakuma, Toshifumi Ishida, and Satoshi Araki
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Hydroxymethylglutaryl-CoA Synthase ,Endocrinology, Diabetes and Metabolism ,Microvesicular Steatosis ,Ketone Bodies ,Mitochondrion ,Energy homeostasis ,Mitochondrial Proteins ,Mice ,Oxygen Consumption ,Physiology (medical) ,Ketogenesis ,Internal Medicine ,Animals ,Mice, Knockout ,Enzyme Gene ,Mice, Inbred ICR ,3-Hydroxybutyric Acid ,ATP synthase ,biology ,Chemistry ,Acetylation ,Cell Biology ,Mitochondria ,Cell biology ,Mice, Inbred C57BL ,Animals, Newborn ,Microvessels ,biology.protein ,Ketone bodies ,Energy Metabolism - Abstract
Ketone bodies are generated in the liver and allow for the maintenance of systemic caloric and energy homeostasis during fasting and caloric restriction. It has previously been demonstrated that neonatal ketogenesis is activated independently of starvation. However, the role of ketogenesis during the perinatal period remains unclear. Here, we show that neonatal ketogenesis plays a protective role in mitochondrial function. We generated a mouse model of insufficient ketogenesis by disrupting the rate-limiting hydroxymethylglutaryl-CoA synthase 2 enzyme gene (Hmgcs2). Hmgcs2 knockout (KO) neonates develop microvesicular steatosis within a few days of birth. Electron microscopic analysis and metabolite profiling indicate a restricted energy production capacity and accumulation of acetyl-CoA in Hmgcs2 KO mice. Furthermore, acetylome analysis of Hmgcs2 KO cells revealed enhanced acetylation of mitochondrial proteins. These findings suggest that neonatal ketogenesis protects the energy-producing capacity of mitochondria by preventing the hyperacetylation of mitochondrial proteins.
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- 2021
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16. The acute effect of dopamine infusion on lipid and cytokine concentrations in persons with a cervical spinal cord injury—a pilot study
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Masumi Nakahama, Christof A. Leicht, Yasunori Umemoto, Victoria L. Goosey-Tolfrey, Sven P. Hoekstra, Yohei Furotani, Fumihiro Tajima, Takayoshi Matsushita, Kazunari Nishiyama, Yasunori Nagano, and Yoshi-ichiro Kamijo
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030506 rehabilitation ,medicine.medical_specialty ,medicine.medical_treatment ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Dopamine ,Internal medicine ,medicine ,Triglyceride ,business.industry ,Interleukin ,Lipid metabolism ,General Medicine ,Endocrinology ,Cytokine ,Acetoacetic acid ,Neurology ,chemistry ,Ketone bodies ,Catecholamine ,Neurology (clinical) ,0305 other medical science ,business ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Study design Acute experimental study. Objectives To investigate the acute response of markers of lipid metabolism and interleukin (IL)-6 to dopamine infusion in people with a cervical spinal cord injury (CSCI). Setting Laboratory of Wakayama Medical University, Japan. Methods Ten participants, four with CSCI and six AB individuals, underwent 50 min of dopamine infusion. Blood samples were collected prior to, immediately after and 1 h following cessation of dopamine infusion for the determination of circulating catecholamine, lipid, ketone body and IL-6 concentrations. Results The adrenaline concentration following dopamine infusion was increased by 59 ± 7% in CSCI (p = 0.038, Cohen's d effect size (ES): 1.47), while this was not changed in AB (p = 0.223). Triglycerides and acetoacetic acid concentration were increased in both groups, immediately after and 1 h post-infusion (triglycerides p ≤ 0.042, ES CSCI: 1.00, ES AB: 1.12; acetoacetic acid p ≤ 0.030; ES CSCI: 1.72, ES AB: 1.31). 3-Hydroxybutyric acid concentration was increased in CSCI only (48 ± 15%, p = 0.039, ES: 1.44; AB p = 0.115). Dopamine infusion did not affect plasma IL-6 concentration in either group (p ≥ 0.368). Conclusions Dopamine infusion induced a sustained increase in triglyceride and ketone body concentrations in persons with CSCI. In contrast, cytokine concentrations were not affected by dopamine infusion. These findings suggest that circulating catecholamines can stimulate metabolism in people with CSCI despite the presence of autonomic dysfunction.
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- 2021
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17. Critical Agglomerate Size for Electrical Insulation Lifetime Extension of Epoxy/TiO2 Nanocomposite with a Void Defect
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Muneaki Kurimoto, Takahiro Umemoto, Hirotaka Muto, and Shigeyoshi Yoshida
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010302 applied physics ,Materials science ,Nanocomposite ,Nanoparticle ,Epoxy ,Critical value ,01 natural sciences ,chemistry.chemical_compound ,chemistry ,Agglomerate ,visual_art ,0103 physical sciences ,Void (composites) ,Titanium dioxide ,Partial discharge ,visual_art.visual_art_medium ,Electrical and Electronic Engineering ,Composite material - Abstract
This study investigates the time to breakdown of epoxy/TiO 2 nanocomposites with a void defect. In the tests, partial discharge (PD) is continuously monitored to clarify the degradation of the nanocomposites. In evaluating the dependence of the maximum agglomerate size and the volume fractions of the TiO 2 particles, it is found that the agglomerate size, rather than the volume fractions, dominates the electrical insulation lifetime of the nanocomposites. Furthermore, the lifetime increases drastically when the agglomerate size exceeds a critical value. The continuous PD signal monitoring reveals that the lifetime extension of the nanocomposites is achieved due to delaying the electrical tree propagation in the nanocomposite, rather than extensions of the times required for the transition from the void discharges to the tree initiation.
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- 2021
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18. Breakdown Strength of TiO2/Epoxy Nanocomposites Using Centrifugation Agglomerate Removal
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Takahiro Mabuchi, Muneaki Kurimoto, Takahiro Umemoto, Hirotaka Muto, and Sigeyoshi Yoshida
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010302 applied physics ,Filler (packaging) ,Materials science ,Nanocomposite ,Nanoparticle ,Epoxy ,01 natural sciences ,chemistry.chemical_compound ,chemistry ,Agglomerate ,visual_art ,0103 physical sciences ,Titanium dioxide ,visual_art.visual_art_medium ,Electrical and Electronic Engineering ,Composite material ,Dispersion (chemistry) ,Curing (chemistry) - Abstract
In this study, TiO 2 /epoxy nanocomposites are evaluated for impulse and AC breakdown strength when agglomerations of TiO 2 nanofillers are removed by centrifugation. It is found that the nanocomposites with micrometric agglomerates exhibit lower breakdown strengths than that of unfilled epoxy resin. However, with the removal of agglomerates larger than 0.5 µm for 0.4 vol% filler concentration, the breakdown strengths are higher than that of unfilled epoxy resin. Micrometric agglomerates of TiO 2 nanoparticles behave as defects, thus lowering the breakdown strength of the nanocomposites. When such agglomerates are removed prior to curing, an improvement of the breakdown strengths is observed with very low filler concentration.
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- 2021
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19. Biocompatible composite of cellulose nanocrystal and hydroxyapatite with large mechanical strength
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Tomohiro Nohara, Akito Masuhara, Ryuichiro Shimada, Keisuke Tabata, Kazuki Umemoto, Kazuki Koseki, Toshihiko Arita, and Ryota Sato
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Aqueous solution ,Fabrication ,Materials science ,Polymers and Plastics ,Composite number ,Pellets ,Compression molding ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Coating ,Nanocrystal ,engineering ,Cellulose ,0210 nano-technology - Abstract
Exploring the simple fabrication process to prepare CNC@HAp for biological tissues is still a challenging subject considering the wide applications of the composites for bio tissues. In this work, aiming for the fabrication of CNC@HAp composites via a simple and environment-friendly process and materials, we propose the neutralization titration in the presence of CNCs in the suspension. Core–shell structured composite of cellulose nanocrystal (CNC) and hydroxyapatite (HAp) (CNC@HAp) was successfully synthesized via simple aqueous neutralization titration. The method studied successfully hybridizes CNCs with a certain amount of HAps and easily controls the coating amounts of HAps from 9 wt% to 17 wt%. In particular, CNC@HAp pellets were easily prepared by simple compression molding from the powder of hybridized CNCs and HAps and the pellets showed high mechanical strength of over 500 N with a low strain of less than 5%. Both the process and the product of the study were environmental-friendly, no toxicity, simple and pure therefore the CNC@HAp can be easily applied to tissue engineering and medical purposes.
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- 2020
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20. Suppressed ER‐associated degradation by intraglomerular cross talk between mesangial cells and podocytes causes podocyte injury in diabetic kidney disease
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Yusuke Hata, Tomoko Kanki, Daisuke Fujimoto, Yoshihiko Nishiguchi, Takashige Kuwabara, Satoru Takahashi, Manabu Hayata, Yutaka Kakizoe, Masashi Mukoyama, Shuro Umemoto, Yuichiro Izumi, and Teruhiko Mizumoto
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Male ,0301 basic medicine ,MafB Transcription Factor ,Mice, Obese ,Apoptosis ,macromolecular substances ,Biochemistry ,Diabetes Mellitus, Experimental ,Podocyte ,Rats, Sprague-Dawley ,Diabetic nephropathy ,Nephrin ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Downregulation and upregulation ,Genetics ,medicine ,Albuminuria ,Animals ,ERAD pathway ,Diabetic Nephropathies ,Molecular Biology ,biology ,Podocytes ,Chemistry ,Endoplasmic reticulum ,Endoplasmic Reticulum-Associated Degradation ,Endoplasmic Reticulum Stress ,medicine.disease ,Rats ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,MAFB ,Mesangial Cells ,biology.protein ,030217 neurology & neurosurgery ,Signal Transduction ,Biotechnology - Abstract
Mesangial lesions and podocyte injury are essential manifestations of the progression of diabetic kidney disease (DKD). Although cross-communication between mesangial cells (MCs) and podocytes has recently been suggested by the results of single-nucleus RNA sequencing analyses, the molecular mechanisms and role in disease progression remain elusive. Our cDNA microarray data of diabetic mouse glomeruli suggested the involvement of endoplasmic reticulum (ER) stress in DKD pathophysiology. In vitro experiments revealed the suppression of the ER-associated degradation (ERAD) pathway and induction of apoptosis in podocytes that were stimulated with the supernatant of MCs cultured in high glucose conditions. In diabetic mice, ERAD inhibition resulted in exacerbated albuminuria, increased apoptosis in podocytes, and reduced nephrin expression associated with the downregulation of ERAD-related biomolecules. Flow cytometry analysis of podocytes isolated from MafB (a transcription factor known to be expressed in macrophages and podocytes)-GFP knock-in mice revealed that ERAD inhibition resulted in decreased nephrin phosphorylation. These findings suggest that an intraglomerular cross talk between MCs and podocytes can inhibit physiological ERAD processes and suppress the phosphorylation of nephrin in podocytes, which thereby lead to podocyte injury under diabetic conditions. Therapeutic intervention of the ERAD pathway through the cross talk between these cells is potentially a novel strategy for DKD.
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- 2020
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21. Pyrene‐Thiol‐modified Pd Nanoparticles on Carbon Support: Kinetic Control by Steric Hinderance and Improved Stability by the Catalyst‐Support Interaction
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Daiki Umemoto, Hirotomo Nishihara, Hiromi Yamashita, Yasutaka Kuwahara, Masanori Yamamoto, Kohsuke Mori, Takeharu Yoshii, and Takashi Kyotani
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chemistry.chemical_classification ,Steric effects ,Catalyst support ,Organic Chemistry ,chemistry.chemical_element ,Photochemistry ,Heterogeneous catalysis ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Thiol ,Surface modification ,Pyrene ,Dehydrogenation ,Physical and Theoretical Chemistry ,Carbon - Published
- 2020
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22. Core Size-Dependent Proton Conductivity of Silica Filler-Functionalized Polymer Electrolyte Membrane
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Ryota Sato, Tomohiro Nohara, Sasiphapa Rodbuntum, Toshihiko Arita, Ryuichiro Shimada, Masaki Takeda, Akito Masuhara, Yukina Suzuki, Kazuki Umemoto, Kazuki Koseki, and Keisuke Tabata
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chemistry.chemical_classification ,Filler (packaging) ,Materials science ,Proton ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Core (manufacturing) ,General Chemistry ,Electrolyte ,Polymer ,Conductivity ,Membrane ,chemistry ,Chemical engineering ,Environmental Chemistry ,Reversible addition−fragmentation chain-transfer polymerization - Abstract
Polymer electrolyte fuel cells (PEFC) are expected as next energy generation systems, and their performance is strongly dependent upon the polymer electrolyte membrane (PEM). We have suggested a ne...
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- 2020
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23. Selective lysine‐specific demethylase 1 inhibitor, NCL1, could cause testicular toxicity via the regulation of apoptosis
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Taku Naiki, Tomoki Takeda, Hiroyuki Kato, Shoichiro Iwatsuki, Takashi Nagai, Satoshi Nozaki, Yukihiro Umemoto, Takayoshi Suzuki, Keitaro Iida, Satoru Takahashi, Takahiro Yasui, Toshiki Etani, and Aya Naiki-Ito
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Male ,Urology ,Endocrinology, Diabetes and Metabolism ,Antineoplastic Agents ,Apoptosis ,Cell Line ,Flow cytometry ,Andrology ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Western blot ,NCL1 ,Testis ,medicine ,Animals ,Humans ,Testosterone ,Viability assay ,Infertility, Male ,Histone Demethylases ,Sertoli Cells ,toxicity in testis ,030219 obstetrics & reproductive medicine ,medicine.diagnostic_test ,Chemistry ,Prostatic Neoplasms ,Original Articles ,Spermatozoa ,spermatogenesis ,Mice, Inbred C57BL ,Blot ,Reproductive Medicine ,Vacuolization ,Hematologic Neoplasms ,Toxicity ,Original Article ,lysine‐specific demethylase 1 ,Spermatogenesis - Abstract
Background Recent studies have shown that epigenetic alterations, such as those involving lysine‐specific demethylase 1 (LSD1), lead to oncogenic activation and highlight such alterations as therapeutic targets. However, studies evaluating the effect of LSD1 inhibitors on male fertility are lacking. Objectives We analyzed the potential toxicity of a new selective LSD1 inhibitor, N‐[(1S)‐3‐[3‐(trans‐2‐aminocyclopropyl)phenoxy]‐1‐(benzylcarbamoyl)propyl] benzamide (NCL1), in testes. Materials and methods Human testicular samples were immunohistochemically analyzed. Six‐week‐old male C57BL/6J mice were injected intraperitoneally with dimethyl sulfoxide vehicle (n = 15), or 1.0 (n = 15) or 3.0 (n = 15) mg/kg NCL1 biweekly. After five weeks, toxicity and gene expression were analyzed in testicular samples by ingenuity pathway analysis (IPA) using RNA sequence data and quantitative reverse transcriptase (qRT)–PCR; hormonal damage was analyzed in blood samples. NCL1 treated GC‐1, TM3, and TM4 cell lines were analyzed by cell viability, chromatin immunoprecipitation, flow cytometry, and Western blot assays. Results LSD1 was mainly expressed in human Sertoli and germ cells, with LSD1 levels significantly decreased in a progressive meiosis‐dependent manner; germ cells showed similar expression patterns in normal spermatogenesis and early/late maturation arrest. Histological examination revealed significantly increased levels of abnormal seminiferous tubules in 3.0 mg/kg NCL1–treated mice compared to control, with increased cellular detachment, sloughing, vacuolization, eosinophilic changes, and TUNEL‐positive cells. IPA and qRT–PCR revealed NCL1 treatment down‐regulated LSD1 activity. NCL1 also reduced total serum testosterone levels. Western blots of mouse testicular samples revealed NCL1 induced a marked elevation in cleaved caspases 3, 7, and 8, and connexin 43 proteins. NCL1 treatment significantly reduced GC‐1, but not TM3 and TM4, cell viability in a dose‐dependent manner. In flow cytometry analysis, NCL1 induced apoptosis in GC‐1 cells. Conclusions High‐dose NCL1 treatment targeting LSD1 caused dysfunctional spermatogenesis and induced caspase‐dependent apoptosis. This suggests the LSD1 inhibitor may cause testicular toxicity via the regulation of apoptosis.
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- 2020
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24. Evaluation of Decomposition Property of Photoresist by Oxygen Radicals Using Helium-Oxygen Mixtures
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Koki Akita, Shiro Nagaoka, Masashi Yamamoto, Hideo Horibe, and Hironobu Umemoto
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Materials science ,Polymers and Plastics ,Chemical engineering ,chemistry ,Radical ,Organic Chemistry ,Materials Chemistry ,Hardening (metallurgy) ,chemistry.chemical_element ,HELIUM/OXYGEN ,Photoresist ,Oxygen - Published
- 2020
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25. Imaging Mass Spectrometry Reveals the Changes in the Taurine Conjugates of Dihydroxycholanoic Acid During Hepatic Warm Ischemia and Reperfusion in a Rat Model
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Kohei Umemoto, Akinobu Taketomi, Sodai Sakamoto, Yuka Hama, Takahisa Ishikawa, Shingo Shimada, Kenji Wakayama, Satsuki Hashimoto, Norio Kawamura, Kengo Shibata, Tsuyoshi Shimamura, Moto Fukai, Nozomi Kobayashi, Takahiro Hayasaka, and Koichi Kato
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Male ,Taurine ,medicine.medical_specialty ,Ischemia ,Intrahepatic bile ducts ,Endogeny ,Tandem mass spectrometry ,Mass spectrometry imaging ,chemistry.chemical_compound ,Internal medicine ,medicine ,Animals ,Warm Ischemia ,cardiovascular diseases ,Transplantation ,medicine.disease ,Rats ,Disease Models, Animal ,Endocrinology ,Liver ,chemistry ,Reperfusion Injury ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Surgery ,Reperfusion injury ,Deoxycholic Acid - Abstract
Warm ischemia and reperfusion injury (IRI) is a prognostic factor in donation after cardiac death donor transplantation. However, a reliable method to predict IRI before transplantation has not been established. The aim of this study was to identify predictive markers of hepatic IRI by simultaneous measurement of endogenous molecules using matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). Rats were subjected to hepatic warm ischemia (70%) for 30 or 90 minutes and subsequent reperfusion. The livers were collected at the end of ischemia and 1 hour, 6 hours, and 24 hours after reperfusion. The liver tissue sections were applied to IMS (m/z 200-2000). Candidate molecules were identified by tandem mass spectrometry. Imaging mass spectrometry (IMS) revealed a significant increase in the taurine conjugates of dihydroxycholanoic acid (TDHCA) during ischemia and a tendency to return to the basal level after reperfusion. Notably, high-resolution measurements revealed focal accumulation of TDHCA in the intrahepatic bile duct with ischemic time. In conclusion, IMS is a useful method to detect minute changes provoked by ischemia, which are barely detectable in assays involving homogenization. Accordingly, focal accumulation of TDHCA during ischemia may be a candidate marker for predicting later IRI.
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- 2020
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26. Optimization of double-layer stress grading system for high voltage rotating electrical machines by electric field and thermal coupled analysis
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Yasutomo Otake, Takahiro Umemoto, Ryoji Miyatake, Takashi Nada, and Manabu Yoshimura
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010302 applied physics ,Materials science ,High voltage ,01 natural sciences ,Stress (mechanics) ,chemistry.chemical_compound ,chemistry ,Electromagnetic coil ,0103 physical sciences ,Arc flash ,Silicon carbide ,Electric potential ,Transient (oscillation) ,Electrical and Electronic Engineering ,Composite material ,Thermal analysis - Abstract
Silicon carbide particle-loaded semi-conductive materials with electric field-dependent conductivity have been used for end-turn stress grading (SG) systems of high voltage rotating electrical machines for decades. Particularly, high voltage class turbogenerators use double-layer SG systems, at which two SG materials with different conductivities are applied, to reduce power dissipations within the SG materials. To prevent the excessive local heating of the SG material and resulting flashover, the field-dependent conductivities of the two SG materials, as well as length of the SG layer in the longitudinal direction along a coil, were optimized, by a nonlinear transient electrical field and thermal coupled analysis. The field-dependent conductivities of the SG materials were adjusted to the suitable ones by changing the average diameter of silicon carbide particles. Then, the appropriate length of the SG layer was selected to minimize the temperature rise in the system. As a result, the newly optimized double-layer SG system showed a 20% lower temperature rise, and more than 15% higher flashover voltage than the conventional ones. Therefore, the effectiveness of the optimized double-layer SG system is successfully confirmed.
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- 2020
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27. Hv1/VSOP regulates neutrophil directional migration and ERK activity by tuning ROS production
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Eiji Umemoto, Yasushi Okamura, and Yoshifumi Okochi
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Mice, Knockout ,MAPK/ERK pathway ,chemistry.chemical_classification ,Reactive oxygen species ,MAP Kinase Signaling System ,Neutrophils ,p38 mitogen-activated protein kinases ,Immunology ,Chemotaxis ,Stimulation ,Cell Biology ,VSOP ,Biology ,Ion Channels ,Cell biology ,Mice, Inbred C57BL ,N-Formylmethionine Leucyl-Phenylalanine ,Chemotaxis, Leukocyte ,Mice ,chemistry ,Knockout mouse ,Animals ,Immunology and Allergy ,Reactive Oxygen Species ,Receptor - Abstract
High-level reactive oxygen species (ROS) production in neutrophils is tightly regulated, as it can damage host cells. Neutrophils also undergo low-level ROS production when stimulated by cytokines or chemoattractants, but its biologic significance remains largely unknown. Voltage-gated proton channels (Hv1/VSOP) activity reportedly supports ROS production in neutrophils; however, we show here that Hv1/VSOP balances ROS production to suppress neutrophil directional migration in the presence of low concentrations of N-formyl-Met-Leu-Phe (fMLF). Neutrophils derived from Hvcn1 gene knockout mice produced more ROS than neutrophils from wild-type mice in the stimulation with fMLF at concentration of 1 µM and nonstimulus condition. They also exhibited stronger chemotactic responses to low concentrations of fMLF than did wild-type neutrophils. Receptor sensitivity to fMLF and evoked Ca2+ responses did not differ between Hv1/VSOP-deficient and wild-type neutrophils. Activation of ERK, but not p38, was enhanced and prolonged during the increased ROS production seen after fMLF stimulation in Hv1/VSOP-deficient neutrophils. Inhibiting ROS production suppressed the enhanced ERK activation in Hv1/VSOP-deficient neutrophils and their directional migration. These results indicate that Hv1/VSOP balances ROS production to reduce ERK signaling and suppress excessive neutrophil migration in response to fMLF. Our findings thus reveal a novel role for ROS in the directional migration of neutrophils.
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- 2020
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28. Incorporation of winter grasses suppresses summer weed germination and affects inorganic nitrogen in flooded paddy soil
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Keitaro Tawaraya, Eko Hanudin, Riza Kurnia Sabri, Putu Oki Bimantara, Weiguo Cheng, Riho Umemoto, Valensi Kautsar, and Asih Indah Utami
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0106 biological sciences ,Milk Vetch ,biology ,Soil Science ,chemistry.chemical_element ,04 agricultural and veterinary sciences ,Plant Science ,biology.organism_classification ,01 natural sciences ,Nitrogen ,Agronomy ,chemistry ,Alopecurus aequalis ,Germination ,Foxtail ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Astragalus sinicus ,Weed ,Inorganic nitrogen ,010606 plant biology & botany - Abstract
Laboratory experiments were conducted to investigate how incorporation of the winter grasses foxtail (Alopecurus aequalis) and milk vetch (Astragalus sinicus) into flooded paddy soil affects the ge...
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- 2020
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29. Ablation of Myeloid Cell MRP8 Ameliorates Nephrotoxic Serum-induced Glomerulonephritis by Affecting Macrophage Characterization through Intraglomerular Crosstalk
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Yuichiro Izumi, Yuki Sato, Yoshihiko Nishiguchi, Hideki Yokoi, Kiyoshi Mori, Masashi Mukoyama, Youngna Kan, Takashige Kuwabara, Yutaka Kakizoe, Daisuke Fujimoto, Shuro Umemoto, Yusuke Hata, Tomoko Kanki, and Motoko Yanagita
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Serum ,0301 basic medicine ,Myeloid ,Kidney Glomerulus ,Cell ,030232 urology & nephrology ,lcsh:Medicine ,Diseases ,Article ,S100A8 ,Mice ,03 medical and health sciences ,Glomerulonephritis ,0302 clinical medicine ,Downregulation and upregulation ,Stress Fibers ,medicine ,Animals ,Calgranulin A ,Cell Lineage ,Lectins, C-Type ,Receptor ,lcsh:Science ,Myeloid Progenitor Cells ,Mice, Knockout ,Recombination, Genetic ,Multidisciplinary ,Integrases ,Chemistry ,Macrophages ,lcsh:R ,Membrane Proteins ,medicine.disease ,Up-Regulation ,Toll-Like Receptor 4 ,Disease Models, Animal ,RAW 264.7 Cells ,030104 developmental biology ,medicine.anatomical_structure ,Nephrology ,Mesangial Cells ,Knockout mouse ,TLR4 ,Cancer research ,lcsh:Q ,Gene Deletion - Abstract
Toll-like receptor 4 (TLR4) and one of its endogenous ligands myeloid-related protein 8 (MRP8 or S100A8), especially expressed in macrophages, play an important role in diabetic nephropathy and autoimmune disorders. However, detailed mechanisms and consequence of MRP8 expression remain unknown, partly due to embryonic lethality of MRP8 knockout mice. In this study, Myeloid lineage cell-specific MRP8 knockout mice were generated, and nephrotoxic serum-induced glomerulonephritis was developed. Mice with conditional ablation of MRP8 gene in myeloid cells exhibited less severe histological damage, proteinuria and inflammatory changes compared to control mice. Mechanism of MRP8 upregulation was investigated using cultured cells. Co-culture of macrophages with mesangial cells or mesangial cell-conditioned media, but not with proximal tubules, markedly upregulated MRP8 gene expression and inflammatory M1 phenotype in macrophages, which was attenuated in MRP8-deleted bone marrow-derived macrophages. Effects of MRP8 deletion was further studied in the context of macrophage-inducible C-type lectin (Mincle), which is critically involved in maintenance of M1 phenotype of macrophages. MRP8 ablation in myeloid cells suppressed the induction of Mincle expression on macrophages in glomerulonephritis. Thus, we propose that intraglomerular crosstalk between mesangial cells and macrophages plays a role in inflammatory changes in glomerulonephritis, and MRP8-dependent Mincle expression in macrophage may be involved in the process.
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- 2020
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30. Tribofilms Produced by Supply of Fine Metal Particles in Vacuum
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Hirotaka Kato, Akihiro Takimi, and Minoru Umemoto
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tribofilm ,fine metal particles ,wear ,pin-on-disc ,bismuth ,Physics ,QC1-999 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Mechanical engineering and machinery ,TJ1-1570 ,Chemistry ,QD1-999 - Abstract
This study demonstrates wear-protective tribofilms produced by an artificial supply of fine metal particles onto rubbing steel surfaces in vacuum. The supplied metal particles were Ag, Bi, Cu, Ni, Ti, and Fe, with the diameters of the particles ranging from 20 nm to 45 μm. The influence of the metal type of the supplied particles on the behavior of tribofilm formation as well as wear of the tribofilms were investigated. When Bi or Ti particles were supplied, the rubbed surfaces were almost entirely covered with the tribofilm. The thickness of the tribofilm produced by supplying Bi particles was 5 ∼ 8 μm. The tribofilms formed by supplying Ag, Bi or Cu particles showed initial low wear in wear tests, and the sliding distance of initial low wear was longer for the tribofilms formed by supplying finer particles. The tribofilms produced by supplying Bi (1.5 μm) particles showed the longest sliding distance of initial low wear.
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- 2011
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31. Synthesis of a Novel Re(I)-Ru(II)-Re(I) Trinuclear Complex as an Effective Photocatalyst for CO2 Reduction
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Osamu Ishitani, Yasuomi Yamazaki, Daiki Saito, Akinari Umemoto, and Yusuke Tamaki
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010405 organic chemistry ,Chemistry ,Supramolecular chemistry ,Photocatalysis ,Photosensitizer ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Redox ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,Artificial photosynthesis - Abstract
Supramolecular photocatalysts, which consist of redox photosensitizer and catalyst units, have recently attracted attention in the field of artificial photosynthesis. Aiming to construct a durable ...
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- 2020
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32. Development of tensile fixture with corrugated structure sheet and estimation of tensile strength of glass fibre fabrics based single face corrugated structure sheet
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Songtam Laosuwan, Shigeru Nagasawa, and Kazuki Umemoto
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Materials science ,Glass fiber ,chemistry.chemical_element ,flexible pins ,shimming tape ,Fixture ,Clamping ,tensile strength ,chemistry ,Breakage ,Aluminium ,Ultimate tensile strength ,lcsh:TA401-492 ,lcsh:Materials of engineering and construction. Mechanics of materials ,Adhesive ,Composite material ,stress concentration ,wavy fixture ,Stress concentration - Abstract
This work aims to reveal the tensile characteristics of Glass Fibre fabrics based single face corrugated Structure Sheet (GFSS) by developing a pressure-adjustable fixture in the machine producing direction of GFSS. In order to set the fixture quick-ready and stable, the effects of several set-up conditions on the tensile behavior of GFSS were investigated. As the set-up condition, a wavy aluminum block fitted to the surface trace, insertion of multiple flexible pins into wave holes, and double-sided tapes attached on the upper/lower surfaces were discussed by changing the number of pins N, and also a few of instant adhesives was dipped on the clamped/pressured zone of GFSS (the reinforced model). Through this study, the followings were revealed. To use multiple polystyrene pins and several pieces of double-sided tapes in the proposed fixture contributes to make the tensile line force stable (as the simple model: without any instant adhesives on the clamped zone). To perform the breakage of liner and wave layers in the area of the gauge span, the reinforced model is usable when choosing N > 1. Investigating the tensile response, the strength (peak maximum line force) and the elongation limit of the liner and wave layers were revealed, respectively. By dipping instant adhesives on the clamping zone when N > 6, the combination resistance of liner and wave braiding structure was actualized.
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- 2020
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33. Effects of Blade Tip Profile on In-Plane Tensile Properties of Wedge-Notched Polypropylene Sheet
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Thepwachara Ruchirabha, Akihiro Yamamoto, Shigeru Nagasawa, and Kazuki Umemoto
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Polypropylene ,0209 industrial biotechnology ,business.product_category ,Materials science ,Crazing ,Mechanical Engineering ,02 engineering and technology ,Work hardening ,Industrial and Manufacturing Engineering ,Wedge (mechanical device) ,chemistry.chemical_compound ,In plane ,Cracking ,020303 mechanical engineering & transports ,020901 industrial engineering & automation ,0203 mechanical engineering ,chemistry ,Ultimate tensile strength ,Composite material ,business - Abstract
In this work, the tensile characteristics of a 0.2-mm-thick polypropylene (PP) sheet subjected to indentation with virgin and blunt knives (apex angle, α=42◦; tip thickness, w=6 and 20 μm, respectively), were experimentally investigated. To determine the effect of mechanical condition, such as the notched depth and the profile of the root surface, on the breaking behavior of the half-cut PP specimen, the tensile testing of the half-cut specimen was carried out by varying the indentation depth and tensile velocity. By the experiments, the breakage behavior of the scored (half-cut) zone was determined by varying the indentation depth, tip thickness of the blade, and elongation rate. A kind of crazing or cracking by the blunt knife decreased the tensile resistance and burr elongation for an indentation depth larger than 0.9, whereas the work hardening by the blunt knife increased these properties for an indentation depth less than 0.8. When a blunt knife was used at a high elongation rate larger than 0.01 s-1, the half-cut zone of the PP sheet exhibited brittle fracture, i.e., the tensile resistance and burr elongation decreased.
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- 2019
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34. 2‐Sulfanylhydroquinone Dimer as a Switchable Fluorescent Dye
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Haruka Umemoto, Sanshiro Sakamoto, Akio Kamimura, Michinori Sumimoto, and Takuji Kawamoto
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Photoluminescence ,010405 organic chemistry ,Dimer ,Organic Chemistry ,General Chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Fluorescence ,Chemical reaction ,Catalysis ,0104 chemical sciences ,Acylation ,chemistry.chemical_compound ,Hydrolysis ,chemistry ,Derivative (chemistry) - Abstract
A new dye was developed, the photoluminescence properties of which are controlled by a chemical reaction. The fluorescence properties of 2-sulfanylhydroquinone dimers depend on the number of hydroxyl groups that are acylated. Unprotected or monoacylated 2-sulfanylhydroquinone dimers displayed good fluorescence properties, whereas diacylated and tetraacylated 2-sulfanylhydroquinone dimers showed dramatically decreased fluorescence. A monomesylated derivative was devised, which shows good fluorescence characteristics as a switching fluorescence dye through a chemical reaction.
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- 2019
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35. A New Lead Identification Strategy: Screening an sp 3 ‐rich and Lead‐like Compound Library Composed of 7‐Azanorbornane Derivatives
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Hideaki Fujii, Yasuhito Uezono, Kanako Miyano, Ryoto Someya, Sho Umemoto, Karin Ashizawa, Naoto Ishibashi, Shigeto Hirayama, Takumi Ogino, Noriko Sato, Tomoya Oki, and Fumika Karaki
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Pharmacology ,010405 organic chemistry ,Chemistry ,Drug discovery ,Organic Chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Lead (geology) ,Drug development ,Drug Discovery ,Click chemistry ,Molecular Medicine ,Identification (biology) ,General Pharmacology, Toxicology and Pharmaceutics - Abstract
Although the advantages of sp3 -rich, sterically complicated molecules in drug development have been pointed out, modern screening libraries are filled with planar, sp2 -rich components. Compounds that are sp3 -rich are difficult to synthesize, and thus we aimed to invent an efficient method to construct sp3 -rich libraries. By modifying sp3 -rich 7-azanorbornane scaffolds through click chemistry, we efficiently prepared a small set of compounds. These compounds were not only sp3 -rich, but also had sufficient "lead-like" properties in view of molecular weights and hydrophobicity. Screening assays of this library provided weak κ opioid receptor agonists and growth hormone secretagogue receptor agonists with high hit rates. These results indicate that the 7-azanorbornane scaffold may be a "privileged structure" for lead identification in drug discovery.
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- 2019
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36. Photoconductive Properties of Dibenzotetrathiafulvalene-Tetracyanoquinodimethane (DBTTF-TCNQ) Nanorods Prepared by the Reprecipitation Method
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Kenta Hojo, Matthew Shuette White, Tsukasa Yoshida, Philipp Stadler, Masaki Takeda, Kazuki Umemoto, Niyazi Serdar Sariciftci, Akito Masuhara, Shuji Okada, Jun Matsui, Madalina Furis, Markus C. Scharber, and Cigdem Yumusak
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Materials science ,Photoconductivity ,Biomedical Engineering ,Bioengineering ,General Chemistry ,Crystal structure ,Condensed Matter Physics ,Tetracyanoquinodimethane ,Evaporation (deposition) ,law.invention ,Crystal ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,General Materials Science ,Nanorod ,Thin film ,Crystallization - Abstract
Charge-transfer complex crystals have been extensively studied because of their metallic conductivity, photoconductivity, ambipolar charge transport, and high career mobility. Numerous studies of their applications for organic electric devices such as organic field effect transistors and solar cells have reported. However, bulky single crystals of charge-transfer complexes are difficult to handle, specifically to be made into a form of a thin film. Recently, nano/micro crystallization of charge-transfer crystal is attracted to realize thin film applications. In this paper, charge transfer complex nanorods composed of dibenzotetrathiafulvalene-tetracyanoquinodimethane (DBTTF-TCNQ) were prepared by the reprecipitation method. The as-formed nanorods possess a kinetically metastable crystal structure different from the thermodynamically stable bulk crystal prepared by slow evaporation of the solvent. From photoconductive measurement, nanorod stacks show a significant photosensitivity (354.57 μA/W) on par with bulk crystal (417.14 μA/W). These results suggest dibenzotetrathiafulvalene-tetracyanoquinodimethane (DBTTF-TCNQ) nanorods have a favorable crystal structure for carrier transport due to the difference of molecular stacking assembly.
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- 2019
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37. Relationship between Oxygen Additive Amount and Photoresist Removal Rate Using H Radicals Generated on an Iridium Hot-Wire Catalyst
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Shiro Nagaoka, Masashi Yamamoto, Hironobu Umemoto, Tomokazu Shikama, Hideo Horibe, and Tomohiro Shiroi
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Materials science ,Polymers and Plastics ,chemistry ,Radical ,Organic Chemistry ,Inorganic chemistry ,Materials Chemistry ,chemistry.chemical_element ,Iridium ,Photoresist ,Oxygen ,Catalysis - Published
- 2019
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38. Oxygen additive effects on decomposition rate of poly(vinyl phenol)-based polymers using hydrogen radicals produced by a tungsten hot-wire catalyst
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Masashi Yamamoto, Hironobu Umemoto, Hideo Horibe, Keisuke Ohdaira, and Shiro Nagaoka
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010302 applied physics ,chemistry.chemical_classification ,Materials science ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,Surfaces and Interfaces ,Polymer ,Tungsten ,Photoresist ,021001 nanoscience & nanotechnology ,01 natural sciences ,Oxygen ,Decomposition ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Catalysis ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,0103 physical sciences ,Materials Chemistry ,Side chain ,Phenol ,0210 nano-technology - Abstract
For fabricating semiconductor devices and for microelectromechanical systems, photoresists are important materials supporting photolithography processes. However, photoresists must be removed for subsequent processes. An earlier study demonstrated that adding a small amount of oxygen gas to the atmosphere in which hydrogen radicals are produced increased the decomposition rate of a positive-tone novolac photoresist. For this study, we prepared polymers with different side chain structures based on poly(vinyl phenol) (PVP). We examined the effects of added oxygen and the oxygen-added hydrogen radicals on the decomposition rates of PVP-based polymers. Hydroxyl groups of PVP are partly substituted with tert-butoxycarbonyl groups in order to use for base polymer of KrF photoresist. Results show that oxygen addition can be useful for KrF photoresist removal.
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- 2019
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39. Wettability of Primer-Treated Al2O3 Surfaces by Bisphenol A Diglycidyl Ether: Determination of the Mechanism from Molecular Dynamics Simulations and Experiments
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Yoshitake Suganuma, Hiroaki Yoneyama, Tomoyuki Kinjo, Kazuhiko Umemoto, Satoru Yamamoto, and Takuya Mitsuoka
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Primer (paint) ,010304 chemical physics ,engineering.material ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Molecular dynamics ,chemistry ,Chemical engineering ,0103 physical sciences ,Materials Chemistry ,engineering ,Wetting ,Physical and Theoretical Chemistry ,Bisphenol A diglycidyl ether - Abstract
This study aims to develop a molecular dynamics (MD) simulation procedure to investigate the wettability of primer-treated Al2O3 surfaces by bisphenol A diglycidyl ether (BADGE) and to understand t...
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- 2019
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40. Identification of a 3β-Hydroxysteroid Dehydrogenase/ 3-Ketosteroid Reductase Involved in α-Tomatine Biosynthesis in Tomato
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Midori Kobayashi, Toshiya Muranaka, Masaru Nakayasu, Yukihiro Sugimoto, Kazuki Saito, Masaharu Mizutani, Haruka Miyachi, Ryota Akiyama, Hyoung Jae Lee, and Naoyuki Umemoto
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0106 biological sciences ,0301 basic medicine ,3-Hydroxysteroid Dehydrogenases ,Physiology ,Plant Science ,Reductase ,Genes, Plant ,Real-Time Polymerase Chain Reaction ,01 natural sciences ,Tomatine ,03 medical and health sciences ,chemistry.chemical_compound ,Solanum lycopersicum ,Biosynthesis ,Genetically modified tomato ,Phylogeny ,Plant Proteins ,Alcohol dehydrogenase ,chemistry.chemical_classification ,biology ,Chemistry ,fungi ,food and beverages ,Cell Biology ,General Medicine ,biology.organism_classification ,030104 developmental biology ,Aglycone ,Enzyme ,Biochemistry ,biology.protein ,Solanum ,Metabolic Networks and Pathways ,010606 plant biology & botany - Abstract
α-Tomatine and dehydrotomatine are major steroidal glycoalkaloids (SGAs) that accumulate in the mature green fruits, leaves and flowers of tomato (Solanum lycopersicum), and function as defensive compounds against bacteria, fungi, insects and animals. The aglycone of dehydrotomatine is dehydrotomatidine (5,6-dehydrogenated tomatidine, having the Δ5,6 double bond; the dehydro-type). The aglycone of α-tomatine is tomatidine (having a single bond between C5 and C6; the dihydro-type), which is believed to be derived from dehydrotomatidine via four reaction steps: C3 oxidation, isomerization, C5 reduction and C3 reduction; however, these conversion processes remain uncharacterized. In the present study, we demonstrate that a short-chain alcohol dehydrogenase/reductase designated Sl3βHSD is involved in the conversion of dehydrotomatidine to tomatidine in tomato. Sl3βHSD1 expression was observed to be high in the flowers, leaves and mature green fruits of tomato, in which high amounts of α-tomatine are accumulated. Biochemical analysis of the recombinant Sl3βHSD1 protein revealed that Sl3βHSD1 catalyzes the C3 oxidation of dehydrotomatidine to form tomatid-4-en-3-one and also catalyzes the NADH-dependent C3 reduction of a 3-ketosteroid (tomatid-3-one) to form tomatidine. Furthermore, during co-incubation of Sl3βHSD1 with SlS5αR1 (steroid 5α-reductase) the four reaction steps converting dehydrotomatidine to tomatidine were completed. Sl3βHSD1-silenced transgenic tomato plants accumulated dehydrotomatine, with corresponding decreases in α-tomatine content. Furthermore, the constitutive expression of Sl3βHSD1 in potato hairy roots resulted in the conversion of potato SGAs to the dihydro-type SGAs. These results demonstrate that Sl3βHSD1 is a key enzyme involved in the conversion processes from dehydrotomatidine to tomatidine in α-tomatine biosynthesis.
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- 2019
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41. Contrast-Induced Nephropathy and Long-Term Clinical Outcomes Following Percutaneous Coronary Intervention in Patients With Advanced Renal Dysfunction (Estimated Glomerular Filtration Rate <30 ml/min/1.73 m2)
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Naoyuki Yoshioka, Akihito Tanaka, Norio Umemoto, Masato Watarai, Hideki Ishii, Toyoaki Murohara, Susumu Suzuki, Kensuke Takagi, Yosuke Negishi, Hiroshi Asano, Yosuke Inoue, Naoki Shibata, Itsuro Morishima, and Yusuke Uemura
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medicine.medical_specialty ,medicine.medical_treatment ,Population ,030232 urology & nephrology ,Urology ,Contrast-induced nephropathy ,Renal function ,030204 cardiovascular system & hematology ,urologic and male genital diseases ,Nephropathy ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,medicine ,education ,Dialysis ,Creatinine ,education.field_of_study ,business.industry ,Percutaneous coronary intervention ,medicine.disease ,surgical procedures, operative ,chemistry ,Conventional PCI ,Cardiology ,Cardiology and Cardiovascular Medicine ,business - Abstract
The incidence of contrast-induced nephropathy (CIN) increases with the progression of renal dysfunction. Recent reports have shown that percutaneous coronary intervention (PCI) can be safely performed even in patients with advanced renal dysfunction by appropriate CIN-prevention strategies. However, data are limited regarding the occurrence and prognostic influence of CIN in patients with advanced renal dysfunction. We examined the data obtained from 323 consecutive patients with advanced renal dysfunction (eGFR
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- 2019
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42. Tomato E8 Encodes a C-27 Hydroxylase in Metabolic Detoxification of α-Tomatine during Fruit Ripening
- Author
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Toshiya Muranaka, Ryota Akiyama, Masaru Nakayasu, Midori Kobayashi, Hyoung Jae Lee, Kazuki Saito, Junpei Kato, Naoyuki Umemoto, Yoko Iijima, Yukihiro Sugimoto, and Masaharu Mizutani
- Subjects
0106 biological sciences ,0301 basic medicine ,Ethylene ,Physiology ,Plant Science ,01 natural sciences ,Mixed Function Oxygenases ,Substrate Specificity ,Hydroxylation ,03 medical and health sciences ,chemistry.chemical_compound ,Tomatine ,Glycoalkaloid ,Solanum lycopersicum ,Genetically modified tomato ,Phylogeny ,Plant Proteins ,chemistry.chemical_classification ,biology ,fungi ,food and beverages ,Ripening ,Cell Biology ,General Medicine ,Saponins ,biology.organism_classification ,Plants, Genetically Modified ,Recombinant Proteins ,Horticulture ,030104 developmental biology ,Enzyme ,chemistry ,Fruit ,Solanum ,010606 plant biology & botany - Abstract
Tomato (Solanum lycopersicum) contains α-tomatine, a steroidal glycoalkaloid that contributes to the plant defense against pathogens and herbivores through its bitter taste and toxicity. It accumulates at high levels in all the plant tissues, especially in leaves and immature green fruits, whereas it decreases during fruit ripening through metabolic conversion to the nontoxic esculeoside A, which accumulates in the mature red fruit. This study aimed to identify the gene encoding a C-27 hydroxylase that is a key enzyme in the metabolic conversion of α-tomatine to esculeoside A. The E8 gene, encoding a 2-oxoglutalate-dependent dioxygenase, is well known as an inducible gene in response to ethylene during fruit ripening. The recombinant E8 was found to catalyze the C-27 hydroxylation of lycoperoside C to produce prosapogenin A and is designated as Sl27DOX. The ripe fruit of E8/Sl27DOX-silenced transgenic tomato plants accumulated lycoperoside C and exhibited decreased esculeoside A levels compared with the wild-type (WT) plants. Furthermore, E8/Sl27DOX deletion in tomato accessions resulted in higher lycoperoside C levels in ripe fruits than in WT plants. Thus, E8/Sl27DOX functions as a C-27 hydroxylase of lycoperoside C in the metabolic detoxification of α-tomatine during tomato fruit ripening, and the efficient detoxification by E8/27DOX may provide an advantage in the domestication of cultivated tomatoes.
- Published
- 2021
43. Development of
- Author
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Teruo, Umemoto, Yuhao, Yang, and Gerald B, Hammond
- Subjects
fluorodiazoniabicyclo[2.2.2]octane salt ,Chemistry ,fluorosulfonimide ,Organic Chemistry ,N-F fluorinating agent ,Review ,fluoropyridinium salt ,fluorination - Abstract
This review deals with the historical development of all N-F fluorinating agents developed so far. The unique properties of fluorine make fluorinated organic compounds attractive in many research areas and therefore fluorinating agents are important. N-F agents have proven useful by virtue of their easy handling. This reagent class includes many types of N-F compounds: perfluoro-N-fluoropiperidine, N-fluoro-2-pyridone, N-fluoro-N-alkylarenesulfonamides, N-fluoropyridinium salts and derivatives, N-fluoroquinuclidium salts, N-fluoro-trifluoromethanesulfonimide, N-fluoro-sultams, N-fluoro-benzothiazole dioxides, N-fluoro-lactams, N-fluoro-o-benzenedisulfonimide, N-fluoro-benzenesulfonimide, 1-alkyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluoropyridinium-2-sulfonate derivatives, 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluorodinitroimidazole, N-fluoro-trichloro-1,3,5-triazinium salt, N-F ethano-Tröger’s base derivatives, N-fluoro-methanesulfonimide, N-fluoro-N-arylarenesulfonamides, bisN-F salts such as N,N’-difluorobipyridinium salts and N,N’-difluoro-1,4-diazoniabicyclo[2.2.2]octane salts, and their many derivatives and analogs, including chiral N-F reagents such as optically active N-fluoro-sultam derivatives, N-fluoro-alkaloid derivatives, DABCO-based N-F derivatives, and N-F binaphthyldisulfonimides. The synthesis and reactions of these reagents are described chronologically and the review also discusses the relative fluorination power of each reagent and their mechanisms chronicling developments from a historical perspective.
- Published
- 2021
44. Effect of pore diameter on the elution behavior of analytes from thermoresponsive polymer grafted beads packed columns
- Author
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Kenichi Nagase, Yuta Umemoto, and Hideko Kanazawa
- Subjects
Analyte ,Science ,02 engineering and technology ,Bead ,010402 general chemistry ,Methacrylate ,01 natural sciences ,Article ,Copolymer ,Thermoresponsive polymers in chromatography ,Packed bed ,chemistry.chemical_classification ,Multidisciplinary ,Chromatography ,Chemistry ,Elution ,Polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Green chemistry ,visual_art ,visual_art.visual_art_medium ,Medicine ,0210 nano-technology ,Analytical chemistry - Abstract
Temperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. Analyte elution behavior in this type of chromatography depends on the modified thermoresponsive polymer and the structure of the base materials. In the present study, we examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. Poly(N-isopropylacrylamide-co-n-butyl methacrylate) hydrogel was applied to beads of various pore sizes: 7, 12, and 30 nm. Almost the same amount of copolymer hydrogel was applied to all beads, indicating that the efficiency of copolymer modification was independent of pore size. Analyte retention on prepared beads in a packed column was observed using steroids, benzodiazepines, and barbiturates as analytes. Analyte retention times increased with temperature on packed columns of 12- and 30-nm beads, whereas the column packed with 7-nm beads exhibited decreased retention times with increasing temperature. The difference in analyte elution behavior among the various pore sizes was attributed to analyte diffusion into the bead pores. These results demonstrate that bead pore diameter determines temperature-dependent elution behavior.
- Published
- 2021
45. Experimental and Numerical Simulation Study of Devolatilization in a Self-Wiping Corotating Parallel Twin-Screw Extruder
- Author
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Yuya Sasai, Masatoshi Ohara, Shin-ichi Kihara, Shin-ichiro Tanifuji, Sho Umemoto, Yuya Obata, Takemasa Sugiyama, and Kentaro Taki
- Subjects
twin-screw extruder ,Work (thermodynamics) ,Materials science ,Polymers and Plastics ,Plastics extrusion ,02 engineering and technology ,Die swell ,Article ,lcsh:QD241-441 ,chemistry.chemical_compound ,Screw thread ,lcsh:Organic chemistry ,020401 chemical engineering ,toluene ,0204 chemical engineering ,Composite material ,Polypropylene ,2.5D Hele–Shaw flow ,Rotational speed ,General Chemistry ,021001 nanoscience & nanotechnology ,simulation ,devolatilization ,Finite element method ,Volumetric flow rate ,chemistry ,self-wiping ,0210 nano-technology ,polypropylene - Abstract
Devolatilization is an important process for separating and removing unnecessary residual volatile substances or solvents during the production of polymers using twin-screw extruders. Latinen proposed a surface renewal model to determine the concentration of volatile components in the extrudate of a single-screw extruder. When a twin-screw extruder is used to calculate the concentration, it is necessary to use the exposed surface area of the resin in the starved region of Latinen&rsquo, s model, which, however, is difficult to estimate. In our previous work, we numerically determined resin profiles of the screws using the 2.5D Hele&ndash, Shaw flow model and the finite element method, which helps in estimating the surface area of devolatilization. In this study, we numerically analyzed the volatile concentration of the extrudate in a self-wiping corotating twin-screw extruder using Latinen&rsquo, s surface renewal model along with our resin profile calculation method. The experimental results of the concentrations of the volatile component (toluene) in the extrudate of polypropylene agreed well with its numerical calculation with a relative error of 6.5% (except for the data of the lowest rotational speed). Our results also showed that decreasing the flow rate and increasing the pump capacity were effective for removing the volatile component. The screw pitch of a full-flight screw was not affected by the devolatilization efficiency with a fixed flow rate and screw speed.
- Published
- 2020
46. Enhancement of AC Breakdown Strength of Epoxy TiO2 Nanocomposite by Removing Agglomerates
- Author
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Takahiro Mabuchi, Hirotaka Muto, Shigeyoshi Yoshida, Muneaki Kurimoto, and Takahiro Umemoto
- Subjects
010302 applied physics ,Materials science ,Nanocomposite ,Fabrication ,Nanoparticle ,Epoxy ,01 natural sciences ,Dilution ,chemistry.chemical_compound ,chemistry ,Agglomerate ,visual_art ,0103 physical sciences ,Volume fraction ,Titanium dioxide ,visual_art.visual_art_medium ,Composite material - Abstract
Epoxy nanocomposites (NCs) are known to have advantages when used in the electrical insulation of power equipment. Agglomerates of nanoparticles, which inevitably form during the fabrication process, can affect the insulating properties of the resultant nanocomposites. Our previous research has clarified that the impulse breakdown strength of the solid part, rather than the surface, of epoxy–TiO 2 NCs with agglomerates removed was higher than that of unfilled epoxy resin. Here, we investigated the dependence of the TiO 2 filler volume fraction on the AC breakdown strength of NCs whose agglomerate size was controlled. The volume fraction and the maximum agglomerate size were controlled using a simple dilution procedure and a centrifugation technique. The AC breakdown strength of the NCs was found to increase with decreasing volume fraction of TiO 2 nanoparticles when the maximum agglomerate size was controlled at the same level. The variation of the AC breakdown strength of the NCs decreased with decreasing maximum agglomerate size, suggesting that the existence of agglomerates larger than a critical size could affect the breakdown.
- Published
- 2020
- Full Text
- View/download PDF
47. Critical agglomerate sizes to improve the insulation characteristics of epoxy/TiO2 nanocomposites
- Author
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Muneaki Kurimoto, Shigeyoshi Yoshida, Takahiro Umemoto, Takahiro Mabuchi, and Hirotaka Muto
- Subjects
010302 applied physics ,Range (particle radiation) ,Fabrication ,Nanocomposite ,Materials science ,Nanoparticle ,Epoxy ,01 natural sciences ,chemistry.chemical_compound ,chemistry ,Agglomerate ,visual_art ,0103 physical sciences ,Titanium dioxide ,Partial discharge ,visual_art.visual_art_medium ,Composite material - Abstract
Agglomerates of nanoparticles which inevitably occur in the fabrication process of epoxy nanocomposite can affect the insulation properties of epoxy nanocomposite. This paper presents an attempt to clarify the effect of agglomerate size on two important insulation properties of epoxy/TiO 2 nanocomposite (NC). One is intrinsic AC breakdown strength and the other is long-term partial discharge lifetime. We used a centrifugation technique to control the maximum size of the agglomerates in the range from 5 μm down to 0.05 μm in each sample. As the results, AC intrinsic breakdown strength was increased with decreasing the maximum agglomerate size and became even higher than the neat epoxy resin when the maximum size is less than around 0.05um. On the other hand, partial discharge lifetime decreased with decreasing the maximum agglomerate size. It should be noted that the PD lifetime distinctively decreased when the agglomerate size is less than around 0.2 um indicating the existence of a critical agglomerate size which contribute to the suppression of partial discharge development resulting in the extension of the partial discharge lifetime.
- Published
- 2020
- Full Text
- View/download PDF
48. Light Emission with Partial Discharge at the Stator Coil End of a Rotating Machine under Operating Temperature
- Author
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Takahiro Umemoto, Kazunari Karasawa, Kunihiko Hidaka, Takahiro Nakamura, Hasegawa Yuki, Takaaki Onoda, and Akiko Kumada
- Subjects
010302 applied physics ,Materials science ,01 natural sciences ,Stress (mechanics) ,chemistry.chemical_compound ,chemistry ,Operating temperature ,Electromagnetic coil ,Electric field ,0103 physical sciences ,Partial discharge ,Silicon carbide ,Light emission ,Composite material ,Voltage - Abstract
Electric field grading system (SG system) is introduced to prevent partial discharge at the stator coil end of a rotating machine. The SG system consists of corona armor tape (CAT) and stress grading tape/paint (SGT/SGP). The CAT is a carbon-loaded highly-conductive tape and is wound over the main insulation. A SGT/SGP is a silicon carbide powder-loaded tape/paint with field-dependent conductivity and is wound over partially the end of CAT. In general, the conductivity of SGT/SGP also has temperature dependence, but has little field-dependence under higher temperature condition. The coil temperature under operating condition exceeds 100°C and this means the electric field on the coil end may increase due to the less non-linearity of SGT/SGP. When the temperature is high, the density of air decreases and surface discharge may occur easily even under the same field distribution. To examine this issue, light emission of partial discharge (PD) on a model bar system under 1-kHz AC voltage was observed by a photomultiplier tube and a digital camera equipped with an image intensifier. The temperature on SG system was set to 30, 70, and 100°C. Unexpectedly, light emission from PD became weaker and the light emission area became smaller as the temperature increased. Some reasonable explanations for this are as follows: the change in the occurrence phase of PD: and the amount of water contained in the vicinity of SG system surface. Although further investigation is required, but the unexpected increase in the PD pulses has not been observed so far within the measured range.
- Published
- 2020
- Full Text
- View/download PDF
49. GPR31-dependent dendrite protrusion of intestinal CX3CR1+ cells by bacterial metabolites
- Author
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Hisako Kayama, Junichi Kikuta, Naoki Morita, Junken Aoki, Asuka Inoue, Takeshi Haneda, Kiyoshi Takeda, Masaru Ishii, Ikuo Kimura, Ryu Okumura, Ryusuke Nabeshima, setsuko fujita, Akio Hayashi, Yuichi Maeda, Nobuhiko Okada, Hitomi Mimuro, Toshiyuki Kida, Toshio Imai, and Eiji Umemoto
- Subjects
0301 basic medicine ,Multidisciplinary ,Chemistry ,Dendrite ,Small intestine ,Cell biology ,Lactic acid ,03 medical and health sciences ,GPR31 ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,medicine.anatomical_structure ,Immune system ,Antigen ,030220 oncology & carcinogenesis ,medicine ,Dendrite extension ,Pyruvic acid - Abstract
Small intestinal mononuclear cells that express CX3CR1 (CX3CR1+ cells) regulate immune responses1-5. CX3CR1+ cells take up luminal antigens by protruding their dendrites into the lumen1-4,6. However, it remains unclear how dendrite protrusion by CX3CR1+ cells is induced in the intestine. Here we show in mice that the bacterial metabolites pyruvic acid and lactic acid induce dendrite protrusion via GPR31 in CX3CR1+ cells. Mice that lack GPR31, which was highly and selectively expressed in intestinal CX3CR1+ cells, showed defective dendrite protrusions of CX3CR1+ cells in the small intestine. A methanol-soluble fraction of the small intestinal contents of specific-pathogen-free mice, but not germ-free mice, induced dendrite extension of intestinal CX3CR1+ cells in vitro. We purified a GPR31-activating fraction, and identified lactic acid. Both lactic acid and pyruvic acid induced dendrite extension of CX3CR1+ cells of wild-type mice, but not of Gpr31b-/- mice. Oral administration of lactate and pyruvate enhanced dendrite protrusion of CX3CR1+ cells in the small intestine of wild-type mice, but not in that of Gpr31b-/- mice. Furthermore, wild-type mice treated with lactate or pyruvate showed an enhanced immune response and high resistance to intestinal Salmonella infection. These findings demonstrate that lactate and pyruvate, which are produced in the intestinal lumen in a bacteria-dependent manner, contribute to enhanced immune responses by inducing GPR31-mediated dendrite protrusion of intestinal CX3CR1+ cells.
- Published
- 2019
- Full Text
- View/download PDF
50. A Study of Mechanical Properties and Molecular Motions at Low Temperature of Novel Polyolefin Materials
- Author
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Daisuke Takeuchi, Kohtaro Osakada, Tadashi Umemoto, Hiroki Takeshita, and Katsuhisa Tokumitsu
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Mechanics of Materials ,Mechanical Engineering ,Molecular motion ,General Materials Science ,Composite material ,Condensed Matter Physics ,Polyolefin - Published
- 2019
- Full Text
- View/download PDF
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