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925 results on '"Kikuchi, Tatsuya"'

4. Imaging α-synuclein pathologies in animal models and patients with Parkinson’s and related diseases

Author

Endo, Hironobu, Ono, Maiko, Takado, Yuhei, Matsuoka, Kiwamu, Takahashi, Manami, Tagai, Kenji, Kataoka, Yuko, Hirata, Kosei, Takahata, Keisuke, Seki, Chie, Kokubo, Naomi, Fujinaga, Masayuki, Mori, Wakana, Nagai, Yuji, Mimura, Koki, Kumata, Katsushi, Kikuchi, Tatsuya, Shimozawa, Aki, Mishra, Sushil K., Yamaguchi, Yoshiki, Shimizu, Hiroshi, Kakita, Akiyoshi, Takuwa, Hiroyuki, Shinotoh, Hitoshi, Shimada, Hitoshi, Kimura, Yasuyuki, Ichise, Masanori, Suhara, Tetsuya, Minamimoto, Takafumi, Sahara, Naruhiko, Kawamura, Kazunori, Zhang, Ming-Rong, Hasegawa, Masato, and Higuchi, Makoto

Published
2024
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8. Cysts or necrotic components in pancreatic ductal adenocarcinoma is associated with the risk of EUS-FNA/B complications including needle tract seeding

Author

Terasawa, Hiroyuki, Matsumoto, Kazuyuki, Tanaka, Takehiro, Tomoda, Takeshi, Ogawa, Taiji, Ishihara, Yuki, Kikuchi, Tatsuya, Obata, Taisuke, Oda, Takashi, Matsumi, Akihiro, Miyamoto, Kazuya, Morimoto, Kosaku, Fujii, Yuki, Yamazaki, Tatsuhiro, Uchida, Daisuke, Horiguchi, Shigeru, Tsutsumi, Koichiro, Kato, Hironari, and Otsuka, Motoyuki

Published
2023
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12. Response to the letter: “Predictive factors for transition to conversion therapy in HCC using atezolizumab plus bevacizumab”

Author

Kikuchi, Tatsuya, primary, Takeuchi, Yasuto, additional, Nouso, Kazuhiro, additional, Kariyama, Kazuya, additional, Kuwaki, Kenji, additional, Toshimori, Junichi, additional, Iwado, Shota, additional, Moriya, Akio, additional, Hagihara, Hiroaki, additional, Takabatake, Hiroyuki, additional, Tada, Toshifumi, additional, Yasunaka, Tetsuya, additional, Sakata, Masahiro, additional, Sue, Masahiko, additional, Miyake, Nozomi, additional, Adachi, Takuya, additional, Wada, Nozomu, additional, Onishi, Hideki, additional, Shiraha, Hidenori, additional, Takaki, Akinobu, additional, and Otsuka, Motoyuki, additional

Published
2024
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14. Colossal barocaloric effects in plastic crystals

Author

Li, Bing, Kawakita, Yukinobu, Wang, Hui, Kikuchi, Tatsuya, Yu, Dehong, Yano, Shinichiro, Ren, Weijun, Nakajima, Kenji, and Zhang, Zhidong

Subjects
Condensed Matter - Materials Science
Abstract

Solid-state refrigeration technology based on caloric effects are promising to replace the currently used vapor compression cycles. However, their application is restricted due to limited performances of caloric materials. Here, we have identified colossal barocaloric effects (CBCEs) in a class of disordered solids called plastic crystals. The obtained entropy changes are about 380 J kg-1 K-1 in the representative neopentylglycol around room temperature. Inelastic neutron scattering reveals that the CBCEs in plastic crystals are attributed to the combination of the vast molecular orientational disorder, giant compressibility, and high anharmonic lattice dynamics. Our study establishes the microscopic scenario for CBCEs in plastic crystals and paves a new route to the next-generation solid-state refrigeration technology., Comment: four figures and supplementary materials

Published
2018
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23. Predictive factors for transition to conversion therapy in hepatocellular carcinoma using atezolizumab plus bevacizumab

Author

Kikuchi, Tatsuya, primary, Takeuchi, Yasuto, additional, Nouso, Kazuhiro, additional, Kariyama, Kazuya, additional, Kuwaki, Kenji, additional, Toshimori, Junichi, additional, Iwado, Shota, additional, Moriya, Akio, additional, Hagihara, Hiroaki, additional, Takabatake, Hiroyuki, additional, Tada, Toshifumi, additional, Yasunaka, Tetsuya, additional, Sakata, Masahiro, additional, Sue, Masahiko, additional, Miyake, Nozomi, additional, Adachi, Takuya, additional, Wada, Nozomu, additional, Onishi, Hideki, additional, Shiraha, Hidenori, additional, Takaki, Akinobu, additional, and Otsuka, Motoyuki, additional

Published
2024
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31. Magnetic excitations of the spin-1/2 tetramer substance Cu$_2$$^{114}$Cd$^{11}$B$_2$O$_6$ obtained by inelastic neutron scattering experiments

Author

Hase, Masashi, Nakajima, Kenji, Ohira-Kawamura, Seiko, Kawakita, Yukinobu, Kikuchi, Tatsuya, and Matsumoto, Masashige

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

We performed inelastic neutron scattering experiments on Cu$_2$$^{114}$Cd$^{11}$B$_2$O$_6$ powder. The magnetic excitations at low temperatures are similar to those of the interacting spin-1/2 tetramers in the ordered state. The weak excitations existing above 3 meV suggest that the Higgs mode appears in Cu$_2$CdB$_2$O$_6$ at ambient pressure and zero magnetic field. We evaluated $J_1 = 27.3 \pm 1.0$ and $J_2 = -14.0 \pm 1.4$ meV for the intra-tetramer interactions and $J_3 = -0.4 \pm 0.2$ and $J_4 = 1.4 \pm 0.2$ meV for the inter-tetramer interactions. The spin gap in the isolated spin tetramer was calculated to be 1.6 meV, which is less than the effective inter-tetramer interaction value ($3.6 \pm 0.8$ meV). Therefore, antiferromagnetic long-range order is possible, although the ground state of the isolated spin tetramer is the spin-singlet state. We discuss the temperature dependence of the magnetic excitations., Comment: 9 pages, 7 figures, 1 table

Published
2015
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33. Efficient Reductive N‐11C‐Methylation Using Arylamines or Alkylamines and In Situ–Generated [11C]Formaldehyde From [11C]Methyl Iodide.

Author

Kikuchi, Tatsuya, Okamura, Toshimitsu, and Zhang, Ming‐Rong

Subjects
*METHYL iodide, *ALKYLAMINES, *AROMATIC amines, *FORMALDEHYDE, *AMINATION, *ACETIC acid, *DIMETHYL sulfoxide
Abstract

Reductive N‐11C‐methylation using [11C]formaldehyde and amines has been used to prepare N‐11C‐methylated compounds. However, the yields of the N‐11C‐methylated compounds are often insufficient. In this study, we developed an efficient method for base‐free reductive N‐11C‐methylation that is applicable to a wide variety of substrates, including arylamines bearing electron‐withdrawing and electron‐donating substituents. A 2‐picoline borane complex, which is a stable and mild reductant, was used. Dimethyl sulfoxide was used as the primary reaction solvent, and glacial acetic acid or aqueous acetic acid was used as a cosolvent. While reductive N‐11C‐methylation efficiently proceeded under anhydrous conditions in most cases, the addition of water to the reductive N‐11C‐methylation generally increased the yield of the N‐11C‐methylated compounds. Substrates with hydroxy, carboxyl, nitrile, nitro, ester, amide, and phenone moieties and amine salts were applicable to the reaction. This proposed method for reductive N‐11C‐methylation should be applicable to a wide variety of substrates, including thermo‐labile and base‐sensitive compounds because the reaction was performed under relatively mild conditions (70°C) without the need for a base. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Calciothermic Reduction and Electrolysis of Sulfides in CaCl2 Melt

Author

Suzuki, Ryosuke O., Suzuki, Nobuyoshi, Yashima, Yuta, Natsui, Shungo, Kikuchi, Tatsuya, Davis, Boyd R., editor, Moats, Michael S., editor, Wang, Shijie, editor, Gregurek, Dean, editor, Kapusta, Joël, editor, Battle, Thomas P., editor, Schlesinger, Mark E., editor, Alvear Flores, Gerardo Raul, editor, Jak, Evgueni, editor, Goodall, Graeme, editor, Free, Michael L., editor, Asselin, Edouard, editor, Chagnes, Alexandre, editor, Dreisinger, David, editor, Jeffrey, Matthew, editor, Lee, Jaeheon, editor, Miller, Graeme, editor, Petersen, Jochen, editor, Ciminelli, Virginia S. T., editor, Xu, Qian, editor, Molnar, Ronald, editor, Adams, Jeff, editor, Liu, Wenying, editor, Verbaan, Niels, editor, Goode, John, editor, London, Ian M., editor, Azimi, Gisele, editor, Forstner, Alex, editor, Kappes, Ronel, editor, and Bhambhani, Tarun, editor

Published
2018
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50. Improved synthesis of 6-bromo-7-[11C]methylpurine for clinical use.

Author

Okamura, Toshimitsu, Kikuchi, Tatsuya, Ogawa, Masanao, and Zhang, Ming-Rong

Subjects
*MULTIDRUG resistance-associated proteins, *METHYL triflate, *POLAR solvents, *ETHYL acetate, *POTASSIUM carbonate, *ACETONITRILE
Abstract

Background: Multidrug resistance-associated protein 1 (MRP1), an energy-dependent efflux pump, is expressed widely in various tissues and contributes to many physiological and pathophysiological processes. 6-Bromo-7-[11C]methylpurine ([11C]7m6BP) is expected to be useful for the assessment of MRP1 activity in the human brain and lungs. However, the radiochemical yield (RCY) in the synthesis of [11C]7m6BP was low, limiting its clinical application, because the methylation of the precursor with [11C]CH3I provided primarily the undesired isomer, 6-bromo-9-[11C]methylpurine ([11C]9m6BP). To increase the RCY of [11C]7m6BP, we investigated conditions for improving the [11C]7m6BP/[11C]9m6BP selectivity of the methylation reaction. Results: [11C]7m6BP was manually synthesized via the methylation of 6-bromopurine with [11C]CH3I in various solvents and at different temperatures in the presence of potassium carbonate for 5 min. Several less polar solvents, including tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), and ethyl acetate (AcOEt) improved the [11C]7m6BP/[11C]9m6BP selectivity from 1:1 to 2:1, compared with the conventionally used solvents for the alkylation of 6-halopurines, acetone, acetonitrile, and N,N-dimethylformamide. However, a higher temperature (140 °C or 180 °C) was needed to progress the 11C-methylation in the less polar solvents, and the manual conditions could not be directly translated to an automated synthesis. [11C]Methyl triflate ([11C]CH3OTf) was thus used as a methylating agent to increase the conversion at a lower temperature. The 11C-methylation using [11C]CH3OTf at 100 °C proceeded efficiently in THF, 2-MeTHF, and AcOEt with maintenance of the improved selectivity. Starting from 28 to 34 GBq [11C]CO2, [11C]7m6BP was produced with 2.3–2.6 GBq for THF, 2.7–3.3 GBq for AcOEt, and 2.8–3.9 GBq for 2-MeTHF at approximately 30 min after the end of bombardment (n = 3 per solvent). The isolated RCYs (decay corrected) for THF, 2-MeTHF, and AcOEt were 24–28%, 29–35%, and 22–31% (n = 3), respectively. Conclusions: The use of THF, 2-MeTHF, and AcOEt improved the [11C]7m6BP/[11C]9m6BP selectivity in the methylation reaction, and the improved method provided [11C]7m6BP with sufficient radioactivity for clinical use. [ABSTRACT FROM AUTHOR]

Published
2024
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