153 results on '"Ohkura K"'
Search Results
2. A Model of Curvature-Induced Phase Transitions in Inflationary Universe
- Author
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Hashida, J., Mukaigawa, S., Muta, T., Ohkura, K., and Yamamoto, K.
- Subjects
General Relativity and Quantum Cosmology ,High Energy Physics - Phenomenology - Abstract
Chiral phase transitions driven by space-time curvature effects are investigated in de Sitter space in the supersymmetric Nambu-Jona-Lasinio model with soft supersymmetry breaking. The model is considered to be suitable for the analysis of possible phase transitions in inflationary universe. It is found that a restoration of the broken chiral symmetry takes place in two patterns for increasing curvature : the first order and second order phase transition respectively depending on initial settings of the four-body interaction parameter and the soft supersymmetry breaking parameter. The critical curves expressing the phase boundaries in these parameters are obtained. Cosmological implications of the result are discussed in connection with bubble formations and the creation of cosmic strings during the inflationary era., Comment: 12 pages, 3 figures, REVTeX
- Published
- 1998
- Full Text
- View/download PDF
3. Pattern of Chiral Symmetry Restoration at Finite Temperature in A Supersymmetric Composite Model
- Author
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Hashida, J., Muta, T., and Ohkura, K.
- Subjects
High Energy Physics - Phenomenology - Abstract
The structure of chiral symmetry restorations at finite temperature is thoroughly investigated in the supersymmetric Nambu-Jona-Lasinio model with a soft supersymmetry breaking term. It is found that the broken chiral symmetry at vanishing temperature is restored at sufficiently high temperature in two patterns, i. e., the first order and second order phase transition depending on the choice of the coupling constant $G$ and the supersymmetry breaking parameter $\Delta$. The critical curves expressing the phase boundaries in the $G-\Delta$ plane are completely determined and the dynamically generated fermion mass is calculated as a function of temperature., Comment: 12 pages, 4 figures, REVTeX
- Published
- 1998
- Full Text
- View/download PDF
4. Thermal Restoration of Chiral Symmetry in Supersymmetric Nambu-Jona-Lasinio Model with Soft SUSY Breaking
- Author
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Hashida, J., Muta, T., and Ohkura, K.
- Subjects
High Energy Physics - Phenomenology - Abstract
The supersymmetric version of the Nambu-Jona-Lasinio model is investigated in connection with the chiral symmetry breaking induced by a soft SUSY breaking term. It is found that the broken chiral symmetry due to the soft breaking term is restored at suitably high temperature and the symmetry restoration occurs as first-order phase transitions. The critical temperature at which the chiral symmetry is restored is determined as a function of the strength of the soft breaking term and the field coupling constant. The dynamical fermion mass is calculated at finite temperature. Some possible applications to the breaking scenario of unified field theories are discussed., Comment: 9 pages, 2 figures
- Published
- 1998
- Full Text
- View/download PDF
5. Depression of sink activity precedes the inhibition of biomass production in tomato plants subjected to potassium deficiency stress
- Author
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Kanai, S., Ohkura, K., Adu-Gyamfi, J. J., Mohapatra, P. K., Nguyen, N. T., Saneoka, H., and Fujita, K.
- Published
- 2007
6. Effect of P-deficiency on photoassimilate partitioning and rhythmic changes in fruit and stem diameter of tomato (Lycopersicon esculentum) during fruit growth
- Author
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Fujita, K., Okada, M., Lei, K., Ito, J., Ohkura, K., Adu-Gyamfi, J. J., and Mohapatra, P. K.
- Published
- 2003
7. Large HTS magnet made by improved DI-BSCCO tapes
- Author
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Ohkura, K., Okazaki, T., and Sato, K.
- Subjects
Magnetic fields -- Analysis ,Superconductors -- Thermal properties ,Superconductors -- Magnetic properties ,Bismuth -- Magnetic properties ,Bismuth -- Thermal properties ,Business ,Electronics ,Electronics and electrical industries - Abstract
The performance of the high temperature superconductor (HTS) is progressing rapidly and the enhancement in [J.sub.c] in Bi2223 long wires are achieved. The design study of the magnet by using the latest Dynamically Innovative bismuth-based HTS wire (DI-BSCCO) has shown that the higher magnetic field is produced with almost the same size of the magnet.
- Published
- 2008
8. Compressible bag model and the phase structure
- Author
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Kagiyama, S., Kumamoto, S., Minaka, A., Nakamura, A., Ohkura, K., and Yamaguchi, S.
- Published
- 2002
- Full Text
- View/download PDF
9. Recent progress of HTS magnet using Bi-2223 Ag-sheathed wire
- Author
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Ohmatsu, K., Hahakura, S., Kato, T., Fujino, K., Ohkura, K., and Sato, K.
- Subjects
Electrical wiring -- Usage ,High temperature superconductors -- Usage ,Superconducting magnets -- Design and construction ,Business ,Electronics ,Electronics and electrical industries - Abstract
The progress on the development of high temperature superconducting magnets using Bi-2223 Ag-sheathed wire is reported. Two types of refrigerator cooled high temperature superconducting magnets, namely, a high magnetic field type and a large bore type, were successfully constructed. The magnets were developed using Bi-2223 silver-sheathed tape wire. Results show that one of the most important benefits of the magnets is their capability of rapid excitation.
- Published
- 1999
10. Magnetic separation of kaolin clay using a high temperature superconducting magnet system
- Author
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Iannicelli, J., Pechin, J., Ueyama, M., Ohkura, K., Hayashi, K., Sato, K., Lauder, A., and Rey, C.
- Subjects
High temperature superconductors -- Usage ,Superconducting magnets -- Usage ,Kaolin -- Research ,Business ,Electronics ,Electronics and electrical industries - Abstract
Sumitomo Electric, DuPont and Aquafine successfully employed a high temperature superconducting (HTS) magnet system in separating mineral contaminants from kaolin clay. The magnetic separation effort involved the extraction of paramagnetic and ferromagnetic contaminants from five types of kaolin. Results from brightness tests reveal that conventional and HTS magnets generate consistent brightness at 2.0 T.
- Published
- 1997
11. Development of Ag-sheathed Bi2223 superconducting wires and their application to magnets
- Author
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Hayashi, K., Hahakura, S., Saga, N., Kobayashi, S., Kato, T., Ueyama, M., Kaneko, T., Hikata, T., Ohkura, K., and Sato, K.
- Subjects
Electrical wire -- Research ,Superconductive devices -- Research ,Magnets -- Research ,Business ,Electronics ,Electronics and electrical industries - Abstract
The powder-in-tube technique was utilized in fabricating silver-sheathed BiPbSrCaCuO 223 superconducting long length wires with a high critical current density of 10(super 4) A/cm2. Considerations involving crystal alignment and connectivity between grains and flux pinning were found to be useful in achieving higher critical current densities. High strength and high amperage wires were also also developed for applications in large scale magnets.
- Published
- 1997
12. Two Classifier Systems for Reinforcement Learning of Motion Patterns
- Author
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Yamada, K., Svinin, M., Ohkura, K., Hosoe, S., and Ueda, K.
- Published
- 2001
- Full Text
- View/download PDF
13. Untersuchung weingeisthaltiger pharmazeutischer Präparate
- Author
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Meyer, Walter, Vigreux, H., Kariyone, T., Ohkura, K., Patzsch, H., Jeglinski, H., Nobili, L., Büchi, J., Ruszkowski, M., Herzog, J., Tietz, H., Layons, A. B., Bümming, G., Booth, J. D., and Zimmermann, W.
- Published
- 1935
- Full Text
- View/download PDF
14. 250 * TRANSOESOPHAGEAL SPINAL CORD STIMULATION FOR MOTOR-EVOKED POTENTIAL MONITORING: FEASIBILITY, SAFETY AND STABILITY
- Author
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Tsuda, K., primary, Shiiya, N., additional, Takahashi, D., additional, Ohkura, K., additional, Yamashita, K., additional, and Kando, Y., additional
- Published
- 2014
- Full Text
- View/download PDF
15. Time-invariant Motion Planner in discretized C-Spacetime for MRS
- Author
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Yasuda, T, Ohkura, K, Marchese, F, MARCHESE, FABIO MARIO GUIDO, Yasuda, T, Ohkura, K, Marchese, F, and MARCHESE, FABIO MARIO GUIDO
- Abstract
In this work, a new class of planners for MRS is introduced: Time-invariant Motion Planners, a class of planners that operate indifferently in forward or in backward planningtime direction. Thanks to the specular symmetry (with respect to the timeline) of the motion operators, the planning algorithm can operate both in top-down way (from the goal to the starting pose) or vice versa bottom-up (from the starting pose to the goal) addressing different types of problems. The planner underlying mechanism is an artificial field over a lattice (CAs), where the robots are shrunk to points subjected to attractive and repulsive forces (Lagrangian mechanics). Building a regular manifold of potential values and following its minimum valleys, a trajectory in the spacetime is extracted, corresponding to a robot movement (geometrization of the motion). The potential manifold is constructed on the base of the motion operators. These are the atomic (non interruptible) moves over the space and the time lattice and the set of all of them represents the entire kinematics of a robot. Every robot has its own set and there are contemporarily robots with different kinematics. The manifold emerges from the interaction of the set of operators, the world model and the representation of the robots’ shapes. Using a discretized C-Spacetime, the definition of velocity of a robot becomes an intrinsical (geometrical) property emerging from the interaction between the motion operators and the spacetime. It is fundamental for the correctness of the planning to take care of the actual robot occupancy during an atomic move to avoid collisions with other robots/obstacles. It derives the definition of Motion Silhouette, a conceptual evolution of the Sweeping Silhouette (2002), which is itself an evolution of the Obstacles Enlargement concept by Lozano-Pérez in 1983. To avoid the problem of the swapping of two robots, it is important to take in consideration of the well-known Shannon’s Theorem in the dis
- Published
- 2011
16. Vertebral artery variations in thoracic aortic patients
- Author
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Ohkura, K., primary, Shiiya, N., additional, Washiyama, N., additional, Yamashita, K., additional, Takahashi, D., additional, Tsuda, K., additional, and Kando, Y., additional
- Published
- 2014
- Full Text
- View/download PDF
17. 298 * VERTEBRAL ARTERY VARIATIONS IN THORACIC AORTIC PATIENTS
- Author
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Ohkura, K., primary, Shiiya, N., additional, Washiyama, N., additional, Yamashita, K., additional, and Takahashi, D., additional
- Published
- 2013
- Full Text
- View/download PDF
18. Novel Twin Streptolysin S-Like Peptides Encoded in the sag Operon Homologue of Beta-Hemolytic Streptococcus anginosus
- Author
-
Tabata, A., primary, Nakano, K., additional, Ohkura, K., additional, Tomoyasu, T., additional, Kikuchi, K., additional, Whiley, R. A., additional, and Nagamune, H., additional
- Published
- 2013
- Full Text
- View/download PDF
19. Curvature-induced phase transitions in the inflationary universe : Supersymmetric Nambu–Jona-Lasinio model in de Sitter spacetime
- Author
-
Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., Yamamoto, Kazuhiro, Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., and Yamamoto, Kazuhiro
- Abstract
type:text, The phase structure associated with chiral symmetry is thoroughly investigated in de Sitter spacetime in the supersymmetric Nambu–Jona-Lasinio model with supersymmetry breaking terms. The argument is given in the three and four space-time dimensions in the leading order of the 1/N expansion and it is shown that the phase characteristics of the chiral symmetry is determined by the curvature of de Sitter spacetime. It is found that the symmetry breaking takes place as the first order as well as second order phase transition depending on the choice of the coupling constant and the parameter associated with the supersymmetry breaking term. The critical curves expressing the phase boundary are obtained. We also discuss the model in the context of the chaotic inflation scenario where topological defects (cosmic strings) develop during inflation.
- Published
- 2000
20. Industrial Applications of HTS Coils Using DI-BSCCO Wire
- Author
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Okazaki, T., primary, Ohkura, K., additional, Kato, T., additional, Fujino, K., additional, Hayashi, K., additional, and Sato, K., additional
- Published
- 2006
- Full Text
- View/download PDF
21. Controlled Over Pressure Processing of Bi2223 Long Length Wires
- Author
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Kobayashi, S., primary, Kato, T., additional, Yamazaki, K., additional, Ohkura, K., additional, Fujino, K., additional, Fujikami, J., additional, Ueno, E., additional, Ayai, N., additional, Kikuchi, M., additional, Hayashi, K., additional, Sato, K., additional, and Hata, R., additional
- Published
- 2005
- Full Text
- View/download PDF
22. Model of curvature-induced phase transitions in the inflationary universe
- Author
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Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., Yamamoto, Kazuhiro, Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., and Yamamoto, Kazuhiro
- Abstract
type:text, Chiral phase transitions driven by space-time curvature effects are investigated in de Sitter space in the supersymmetric Nambu–Jona-Lasinio model with soft supersymmetry breaking. The model is considered to be suitable for the analysis of possible phase transitions in inflationary universe. It is found that a restoration of the broken chiral symmetry takes place in two patterns for increasing curvature: the first-order and second-order phase transition, respectively, depending on initial settings of the four-body interaction parameter and the soft supersymmetry breaking parameter. The critical curves expressing the phase boundaries in these parameters are obtained. Cosmological implications of the result are discussed in connection with bubble formations and the creation of cosmic strings during the inflationary era.
- Published
- 1999
23. Thermal restoration of chiral symmetryin supersymmetric Nambu-Jona-Lasinio model with soft SUSY breaking
- Author
-
Hashida, J., Muta, Taizo, Ohkura, K., Hashida, J., Muta, Taizo, and Ohkura, K.
- Abstract
type:text, The supersymmetric version of the Nambu-Jona-Lasinio model is investigated in connection with the chiral symmetry breaking induced by a soft SUSY breaking term. It is found that the broken chiral symmetry due to the soft breaking term is restored at suitably high temperature and the symmetry restoration occurs as first-order phase transitions. The critical temperature at which the chiral symmetry is restored is determined as a function of the strength of the soft breaking term and the field coupling constant. The dynamical fermion mass is calculated at finite temperature. Some possible applications to the breaking scenario of unified field theories are discussed.
- Published
- 1998
24. Stable grasp planning by evolutionary programming
- Author
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Katada, Y., primary, Svinin, M., additional, Ohkura, K., additional, and Ueda, K., additional
- Published
- 2001
- Full Text
- View/download PDF
25. A 12-T forced flow type superconducting magnet.
- Author
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Nishi, M., Takahashi, Y., Ando, T., Shimamoto, S., Takei, H., and Ohkura, K.
- Published
- 1987
- Full Text
- View/download PDF
26. Development of a large high-current-density Nb3Sn superconductor made by solid-liquid diffusion method.
- Author
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Nagata, M., Ohkura, K., Isojima, S., Watanabe, M., Umeda, M., and Kimura, Y.
- Published
- 1985
- Full Text
- View/download PDF
27. IMMUNOGLOBULIN HAPLOTYPES OF TWO POPULATION GROUPS IN IRAN.
- Author
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Loghem, Erna van, Lange, Gerda de, Matsumoto, H., Miyazaki, T., and Ohkura, K.
- Published
- 1977
- Full Text
- View/download PDF
28. Curvature-induced phase transitions in the inflationary universe : Supersymmetric Nambu–Jona-Lasinio model in de Sitter spacetime
- Author
-
Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., Yamamoto, Kazuhiro, Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., and Yamamoto, Kazuhiro
- Abstract
The phase structure associated with chiral symmetry is thoroughly investigated in de Sitter spacetime in the supersymmetric Nambu–Jona-Lasinio model with supersymmetry breaking terms. The argument is given in the three and four space-time dimensions in the leading order of the 1/N expansion and it is shown that the phase characteristics of the chiral symmetry is determined by the curvature of de Sitter spacetime. It is found that the symmetry breaking takes place as the first order as well as second order phase transition depending on the choice of the coupling constant and the parameter associated with the supersymmetry breaking term. The critical curves expressing the phase boundary are obtained. We also discuss the model in the context of the chaotic inflation scenario where topological defects (cosmic strings) develop during inflation.
29. Thermal restoration of chiral symmetryin supersymmetric Nambu-Jona-Lasinio model with soft SUSY breaking
- Author
-
Hashida, J., Muta, Taizo, Ohkura, K., Hashida, J., Muta, Taizo, and Ohkura, K.
- Abstract
The supersymmetric version of the Nambu-Jona-Lasinio model is investigated in connection with the chiral symmetry breaking induced by a soft SUSY breaking term. It is found that the broken chiral symmetry due to the soft breaking term is restored at suitably high temperature and the symmetry restoration occurs as first-order phase transitions. The critical temperature at which the chiral symmetry is restored is determined as a function of the strength of the soft breaking term and the field coupling constant. The dynamical fermion mass is calculated at finite temperature. Some possible applications to the breaking scenario of unified field theories are discussed.
30. Model of curvature-induced phase transitions in the inflationary universe
- Author
-
Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., Yamamoto, Kazuhiro, Hashida, J., Mukaigawa, S., Muta, Taizo, Ohkura, K., and Yamamoto, Kazuhiro
- Abstract
Chiral phase transitions driven by space-time curvature effects are investigated in de Sitter space in the supersymmetric Nambu–Jona-Lasinio model with soft supersymmetry breaking. The model is considered to be suitable for the analysis of possible phase transitions in inflationary universe. It is found that a restoration of the broken chiral symmetry takes place in two patterns for increasing curvature: the first-order and second-order phase transition, respectively, depending on initial settings of the four-body interaction parameter and the soft supersymmetry breaking parameter. The critical curves expressing the phase boundaries in these parameters are obtained. Cosmological implications of the result are discussed in connection with bubble formations and the creation of cosmic strings during the inflationary era.
31. 298VERTEBRAL ARTERY VARIATIONS IN THORACIC AORTIC PATIENTS.
- Author
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Ohkura, K., Shiiya, N., Washiyama, N., Yamashita, K., and Takahashi, D.
- Published
- 2013
- Full Text
- View/download PDF
32. DI-BSCCO wires by Controlled over pressure sintering.
- Author
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Ayai, N., Kato, T., Fujikami, J., Fujino, K., Kobayashi, S., Ueno, E., Yamazaki, K., Kikuchi, M., Ohkura, K., Hayashi, K., Sato, K., and Hata, R.
- Published
- 2006
- Full Text
- View/download PDF
33. Streptolysin S induces proinflammatory cytokine expression in calcium ion-influx-dependent manner.
- Author
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Yamamori Y, Shirai R, Ohkura K, Nagamune H, Tomoyasu T, and Tabata A
- Abstract
Anginosus group streptococci (AGS) are opportunistic pathogens that reside in the human oral cavity. The β-hemolytic strains of Streptococcus anginosus subsp. anginosus (SAA) produce streptolysin S (SLS), a streptococcal peptide hemolysin. In recent clinical scenarios, AGS, including this species, have frequently been isolated from infections and disorders beyond those in the oral cavity. Consequently, investigating this situation will reveal the potential pathogenicity of AGS to ectopic infections in humans. However, the precise mechanism underlying the cellular response induced by secreted SLS and its relevance to the pathogenicity of AGS strains remain largely unknown. This study aims to elucidate the mechanism underlying the host cellular response of the human acute monocytic leukemia cell line THP-1 to secreted SLS. In THP-1 cells incubated with the culture supernatant of β-hemolytic SAA containing SLS as the sole cytotoxic factor, increased Ca
2+ influx and elevated expression of proinflammatory cytokines were observed. Significantly reduced expression of SLS-dependent upregulated cytokine genes under Ca2+ -chelating conditions suggests that Ca2+ influx triggers SLS-dependent cellular responses. Furthermore, SLS-dependent enhanced expression of IL-8 was also implicated in the activation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) signaling pathways. The findings presented in this study are crucial for a comprehensive understanding of the real pathogenicity of SLS-producing β-hemolytic AGS in the latest clinical situations., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Atsushi Tabata reports financial support was provided by Japan Society for the Promotion of Science. Kazuto Ohkura reports financial support was provided by Japan Society for the Promotion of Science. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (© 2024 The Authors.)- Published
- 2024
- Full Text
- View/download PDF
34. Improving the performance of mutation-based evolving artificial neural networks with self-adaptive mutations.
- Author
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Hiraga M, Komura M, Miyamoto A, Morimoto D, and Ohkura K
- Subjects
- Neural Networks, Computer, Mutation, Algorithms
- Abstract
Neuroevolution is a promising approach for designing artificial neural networks using an evolutionary algorithm. Unlike recent trending methods that rely on gradient-based algorithms, neuroevolution can simultaneously evolve the topology and weights of neural networks. In neuroevolution with topological evolution, handling crossover is challenging because of the competing conventions problem. Mutation-based evolving artificial neural network is an alternative topology and weights neuroevolution approach that omits crossover and uses only mutations for genetic variation. This study enhances the performance of mutation-based evolving artificial neural network in two ways. First, the mutation step size controlling the magnitude of the parameter perturbation is automatically adjusted by a self-adaptive mutation mechanism, enabling a balance between exploration and exploitation during the evolution process. Second, the structural mutation probabilities are automatically adjusted depending on the network size, preventing excessive expansion of the topology. The proposed methods are compared with conventional neuroevolution algorithms using locomotion tasks provided in the OpenAI Gym benchmarks. The results demonstrate that the proposed methods with the self-adaptive mutation mechanism can achieve better performance. In addition, the adjustment of structural mutation probabilities can mitigate topological bloat while maintaining performance., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Hiraga et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
- Published
- 2024
- Full Text
- View/download PDF
35. Streptolysin S induces pronounced calcium-ion influx-dependent expression of immediate early genes encoding transcription factors.
- Author
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Yamada T, Yamamori Y, Matsuda N, Nagamune H, Ohkura K, Tomoyasu T, and Tabata A
- Subjects
- Ions, Streptococcus pyogenes, Humans, Genes, Immediate-Early, Streptococcus, Calcium, Transcription Factor AP-1, Mouth Neoplasms, Carcinoma, Squamous Cell, Head and Neck Neoplasms, Betaproteobacteria
- Abstract
Anginosus group streptococci (AGS) are opportunistic human pathogens of the oral cavity. The β-hemolytic subgroup of Streptococcus anginosus subsp. anginosus secretes streptolysin S (SLS) and exhibits not only hemolytic activity but also cytotoxicity toward cultured human cell lines. However, the detailed mechanism of action of SLS and the cellular responses of host cells have not yet been fully clarified. To determine the pathogenic potential of SLS-producing β-hemolytic S. anginosus subsp. anginosus, the SLS-dependent response induced in the human oral squamous cell carcinoma HSC-2 cells was investigated to determine the pathogenic potential of SLS-producing β-hemolytic S. anginosus subsp. anginosus. This study revealed that the Ca
2+ influx and the expression of immediate early genes (IEGs) encoding transcription factors such as early growth responses (EGRs) and activator protein-1 (AP-1) were greatly increased in HSC-2 cells incubated with the culture supernatant of SLS-producing β-hemolytic S. anginosus subsp. anginosus. Moreover, this SLS-dependent increase in expression was significantly suppressed by Ca2+ chelation, except for jun. These results suggest that SLS caused Ca2+ influx into the cells following greatly enhanced expression of IEG-encoding transcription factors. The results of this study may help in understanding the pathogenicity of SLS-producing AGS., (© 2023. Springer Nature Limited.)- Published
- 2023
- Full Text
- View/download PDF
36. Dual functions of discoidinolysin, a cholesterol-dependent cytolysin with N-terminal discoidin domain produced from Streptococcus mitis strain Nm-76.
- Author
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Tabata A, Matsumoto A, Fujimoto A, Ohkura K, Ikeda T, Oda H, Yokohata S, Kobayashi M, Tomoyasu T, Takao A, Ohkuni H, and Nagamune H
- Abstract
Background: Some strains of Streptococcus mitis exhibit β-hemolysis due to the β-hemolytic activity of cholesterol-dependent cytolysin (CDC). Recently, a gene encoding an atypical lectinolysin-related CDC was found in S. mitis strain Nm-76. However, the product of this gene remains uncharacterized. We aimed to characterize this atypical CDC and its molecular functions and contribution to the pathogenicity of S. mitis strain Nm-76., Methods: Phylogenetic analysis of the CDC gene was conducted based on the web-deposited information. The molecular characteristics of CDC were investigated using a gene-deletion mutant strain and recombinant proteins expressed in Escherichia coli ., Results: The gene encoding CDC found in Nm-76 and its homolog are distributed among many S. mitis strains. This CDC is phylogenetically different from other previously characterized CDCs, such as S. mitis -derived human platelet aggregation factor (Sm-hPAF)/lectinolysin and mitilysin. Because this CDC possesses an additional N-terminal domain, including a discoidin motif, it was termed discoidinolysin (DLY). In addition to the preferential lysis of human cells, DLY displayed N-terminal domain-dependent facilitation of human erythrocyte aggregation and intercellular associations between human cells., Conclusion: DLY functions as a hemolysin/cytolysin and erythrocyte aggregation/intercellular association molecule. This dual-function DLY could be an additional virulence factor in S. mitis ., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)
- Published
- 2022
- Full Text
- View/download PDF
37. Construction of a Drug Release Evaluation System: Application of Mitochondrial Respiration to Monitor Drug Release.
- Author
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Ohkura K, Tatematsu Y, and Tabata A
- Subjects
- Alginates chemistry, Animals, Anti-Inflammatory Agents, Non-Steroidal chemistry, Cell Respiration, Diclofenac chemistry, Drug Carriers chemistry, Mefenamic Acid chemistry, Nitriles chemistry, Rats, Uncoupling Agents chemistry, Drug Liberation, Mitochondria, Liver metabolism, Oxygen metabolism
- Abstract
Background/aim: Efficient drug encapsulation and regulation of drug release are important factors for sustained drug release and application for release-controlled anti-cancer and anti-inflammatory drug delivery. In the present study, a direct evaluation system for drug-release from model carrier (e.g., alginate-gel beads) was examined using the mitochondrial oxygen consumption rate as an index., Materials and Methods: Alginate-gel beads were coated with the uncoupler SF6847 (SF beads) and used as a model microparticle-type drug. The real-time monitoring of SF6847 release from prepared alginate-gel beads was performed using the mitochondrial oxygen consumption rate. Release profiles of nonsteroidal anti-inflammatory drugs [NSAIDs, mefenamic acid (MEF) and diclofenac (DIC)] from alginate-gel beads as well as SF beads were investigated using the real time monitoring system., Results: SF6847 release from alginate-gel beads was clearly detected using the rat liver mitochondrial oxygen consumption rate. The release features of MEF and DIC from alginate-gel beads were defined by the present trial monitoring system, and these NSAIDs exhibited different release profiles., Conclusion: The present drug monitoring system detected released drugs, and the release profile reflected the molecular properties of the test drugs. This system may be applied to the design and development of precise sustained drug release systems (e.g., anti-cancer and anti-inflammatory drugs)., (Copyright © 2021 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
38. Type B Acute Aortic Dissection as a Perioperative Complication after an Endovascular Abdominal Aortic Repair.
- Author
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Natsume K, Shintani T, Hayahi M, Ohkura K, Hasegawa Y, and Ariya T
- Abstract
Type B aortic dissection (TBAD) is a rare but catastrophic complication of endovascular aneurysm repair (EVAR). We report two cases of TBAD occurring in the perioperative period of EVAR. The intraoperative and postoperative courses were unremarkable. Routine postoperative computed tomography angiography (CTA) revealed TBAD. Conservative treatment was successful, and no adverse aortic events occurred. TBAD that occurs in the perioperative period is likely to be iatrogenic in origin, uncomplicated, and managed with medical therapy: its prognosis is better than when the condition develops in the midterm postoperative period., Competing Interests: Disclosure StatementThe authors declare no conflict of interest., (© 2021 The Editorial Committee of Annals of Vascular Diseases.)
- Published
- 2021
- Full Text
- View/download PDF
39. Effect of Isomerization of TX-2036 Derivatives on the Interaction With Tyrosine Kinase Domain of EGF Receptor.
- Author
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Ohkura K, Tabata A, Uto Y, and Hori H
- Subjects
- Antineoplastic Agents pharmacology, Binding Sites, Cell Line, Tumor, ErbB Receptors metabolism, Humans, Isomerism, Radiation-Sensitizing Agents pharmacology, Stereoisomerism, Protein Domains drug effects, Protein Kinase Inhibitors pharmacology
- Abstract
Background: From the design and synthesis of enantiomers, we can expect to obtain two compounds with different pharmacokinetics and pharmacological activities at the same time, which is thought to lead to the development of efficient anticancer agents. Chiral-2-nitroimidazole TX-2036 derivatives exhibit stereo-configuration (R- and S-configuration)-dependent tyrosine kinase inhibitory activity, and the activity of the tyrosine kinase domain of EGF receptor (EGFR-tyk) is suppressed. In order to clarify the reason why the effects on EGFR-tyk activity differ depending on stereoisomers, we tried to analyze the interaction between each TX-2036 derivative and EGFR-tyk., Materials and Methods: The 2-nitroimidazole-based radiosensitizer TX-2036 series were synthesized and their molecular features were examined using protein kinase inhibition assay and molecular structural analysis., Results: R-configured TXs (TX-2043, -2030, and -2036) exhibited more potent protein kinase inhibitory activity than S-configured TXs (TX-2044, - 2031, and -2037), and the IC
50 value of TX-2036 was 1.8 μM., Conclusion: R-configured TXs interacted with Lys721 and Thr766 of EGFR-tyk. The combinations of amino acid residues targeted by the S-configured TXs were different from each other (Ile765 and Thr766 (TX-2044), Ser696 , Thr766 , and Thr830 (TX-2031), Gly772 , Cys773 , and Thr830 (TX-2037)). Preparing a series of isomers with different target sites was considered beneficial when the target was mutated., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)- Published
- 2020
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40. Correlation Between Radiosensitizing Activity and the Stereo-structure of the TX-2036 Series of Molecules.
- Author
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Ohkura K, Tabata A, Uto Y, and Hori H
- Subjects
- Cell Hypoxia drug effects, Cyclopentanes chemical synthesis, Cyclopentanes chemistry, Humans, Nitroimidazoles chemical synthesis, Radiation-Sensitizing Agents chemical synthesis, Static Electricity, Stereoisomerism, Structure-Activity Relationship, Drug Design, Nitroimidazoles chemistry, Radiation Tolerance drug effects, Radiation-Sensitizing Agents chemistry
- Abstract
Background/aim: The stereo-configuration (R-, S-configuration) of chiral-2-nitroimidazole derivatives alters their radiosensitizing activity. This study aimed at examining the molecular features of these enantiomers by molecular simulation techniques., Materials and Methods: A series of 2-nitroimidazole-based radiosensitizer TX-2036 molecules were synthesized, and their profiles were examined using molecular structural analysis such as conformation analysis, molecular orbital analysis, and electrostatic potential analysis., Results: R-configured TXs (TX-2043, -2030, -2036) had a weaker radiosensitizing activity than S-configured TXs (TX-2044, -2031, -2037), and R-compounds had a small minus electrostatic potential (ESP) field in the cyclopentene-1,3-dione region. S-configured TX-2046 had weaker radiosensitizing activity than R-configured TX-2045, and TX-2046 had a small minus ESP field as well as R-configured TX-2043, -2030, - 2036., Conclusion: The cyclopentene-1,3-dione involved in the small minus ESP field affected the radiosensitizing activity of the TX-2036 series of molecules., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)
- Published
- 2019
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- View/download PDF
41. β-Hemolytic Streptococcus anginosus subsp. anginosus causes streptolysin S-dependent cytotoxicity to human cell culture lines in vitro .
- Author
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Tabata A, Yamada T, Ohtani H, Ohkura K, Tomoyasu T, and Nagamune H
- Abstract
Background: Streptococcus anginosus subsp. anginosus (SAA) is one of the opportunistic pathogens in humans that inhabits the oral cavity. The type strain of SAA, NCTC10713
T , showed clear β-hemolysis on blood agar plates, and the sole β-hemolytic factor revealed two streptolysin S (SLS) molecules. SLS is well known as the peptide hemolysin produced from the human pathogen S. pyogenes and shows not only hemolytic activity on erythrocytes but also cytotoxic activity in cell culture lines in vitro and in vivo , such as in a mouse infection model. However, no cytotoxic activity of SLS produced from β-hemolytic SAA (β-SAA) has been reported so far. Objective and Design: In this study, the SLS-dependent cytotoxicity of the β-SAA strains including the genetically modified strains was investigated in vitro . Results: The SLS-producing β-SAA showed cytotoxicity in human cell culture lines under the co-cultivation condition and it was found that this cytotoxicity was caused by the SLS secreted into the extracellular milieu. Conclusion: The results from this study suggest that the SLS produced from β-SAA might indicate the cytotoxic potential similar to that of the SLS from S. pyogenes and the SLS-producing β-SAA would be recognized as "a wolf in sheep's clothing" More attention will be paid to the pathogenicity of β-hemolytic Anginosus group streptococci.- Published
- 2019
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42. Structure-associated Functional Control of TX-1877 Series by Glyco-conjugation.
- Author
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Ohkura K, Kawaguchi Y, Tatematsu Y, Tabata A, Uto Y, and Hori H
- Subjects
- Animals, Cell Line, Glycosylation, Mice, Drug Design, Nitroimidazoles chemistry, Radiation-Sensitizing Agents chemistry, Structure-Activity Relationship
- Abstract
Background/aim: Sugar molecules are often used as a tool to structurally modify chemical compounds. The features of synthesized sugar-conjugated TX-1877 derivatives were herein examined., Materials and Methods: The molecular stabilities (reactivity) and hydrophobicities of sugar (e.g., monosaccharide and tetra-O-acetylated monosaccharide)-conjugated TXs were analyzed using a molecular simulation (e.g. molecular mechanics (MM) and molecular orbital (MO) analysis)., Results: The hydrophobicities of TX-1877 derivatives were increased by tetra-O-acetylation, and TX-2244 exhibited the most potent radiosensitizing activity (enhancement ratio: ER=2.30)., Conclusion: The conformations and hydrophobicities of chemical compounds may be controlled by adding monosaccharide- and tetra-O-acetyl-conjugated sugars to TX-1877., (Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
43. Carotid stenosis with impaired brain flow reserve is associated with an increased risk of stroke in on-pump cardiovascular surgery.
- Author
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Tsuda K, Shiiya N, Washiyama N, Yamashita K, Ohkura K, Takahashi D, Kando Y, Natsume K, Yamanaka K, and Takeuchi Y
- Subjects
- Acetazolamide, Aged, Aged, 80 and over, Carotid Stenosis diagnostic imaging, Female, Humans, Magnetic Resonance Angiography, Male, Middle Aged, Retrospective Studies, Risk Factors, Stroke diagnostic imaging, Stroke physiopathology, Tomography, Emission-Computed, Single-Photon, Carotid Stenosis complications, Carotid Stenosis physiopathology, Cerebrovascular Circulation physiology, Postoperative Complications epidemiology, Stroke epidemiology, Vascular Surgical Procedures adverse effects
- Abstract
Objectives: To prevent haemodynamic stroke during cardiovascular surgery in patients with carotid stenosis, we routinely evaluated magnetic resonance angiography and selectively evaluated brain perfusion single-photon emission computed tomography with acetazolamide challenge. Off-pump surgery was preferred when cerebral blood flow reserve was impaired. This strategy's usefulness was investigated., Methods: Among the 1059 consecutive patients who underwent preoperative carotid screening by magnetic resonance angiography, 84 (7.9%) patients had >50% stenosis; 45 of them underwent brain single-photon emission computed tomography. The severity of cerebral blood flow compromise was estimated by the proportion of Stage 2 area in the affected territory, in which both resting blood flow (<32 ml/min) and flow reserve (<10%) were reduced., Results: Perioperative stroke occurred in 1.7% overall (18/1059), in 6% (5/84) of those with carotid stenosis and in 1.3% (13/975) of those without stenosis (P = 0.010). On subgroup analysis, carotid stenosis was associated with an increased risk of stroke in the on-pump surgery group [n = 949, 5/59 (9%) with stenosis vs 11/890 (1.1%) without stenosis, P = 0.002], while it was not in the off-pump group [n = 110, 0/25 (0%) with stenosis vs 2/85 (2%) without stenosis, P = 0.59]. With respect to the role of acetazolamide single-photon emission computed tomography, 2 of the 4 patients with Stage 2 area >10% undergoing on-pump surgery without preceding carotid revascularization developed stroke, while none of the 21 patients with Stage 2 area <10% undergoing on-pump surgery developed stroke (P = 0.020)., Conclusions: Carotid stenosis is a risk factor for perioperative stroke in on-pump surgery. Patients with large Stage 2 area (>10%) are at increased risk of perioperative stroke when on-pump surgery is performed.
- Published
- 2018
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44. N-methyl-d-aspartate receptor dysfunction in the prefrontal cortex of stroke-prone spontaneously hypertensive rat/Ezo as a rat model of attention deficit/hyperactivity disorder.
- Author
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Shikanai H, Oshima N, Kawashima H, Kimura SI, Hiraide S, Togashi H, Iizuka K, Ohkura K, and Izumi T
- Subjects
- Animals, Attention Deficit Disorder with Hyperactivity complications, Attention Deficit Disorder with Hyperactivity pathology, Disease Models, Animal, Dizocilpine Maleate pharmacology, Excitatory Amino Acid Antagonists pharmacology, Hypertension complications, Long-Term Potentiation, Male, Prefrontal Cortex cytology, Pyramidal Cells drug effects, Pyramidal Cells metabolism, Pyramidal Cells physiology, Rats, Rats, Inbred SHR, Rats, Wistar, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors, Attention Deficit Disorder with Hyperactivity metabolism, Hypertension metabolism, Prefrontal Cortex metabolism, Receptors, N-Methyl-D-Aspartate metabolism
- Abstract
Aim: We previously reported that stroke-prone spontaneously hypertensive rat/Ezo (SHRSP/Ezo) has high validity as an attention deficit/hyperactivity disorder (AD/HD) animal model, based on its behavioral phenotypes, such as inattention, hyperactivity, and impulsivity. Fronto-cortical dysfunction is implicated in the pathogenesis of AD/HD. In this study, we investigated prefrontal cortex (PFC) function in SHRSP/Ezo rats by electrophysiological methods and radioreceptor assay., Methods: We recorded excitatory postsynaptic potential in layer V pyramidal neurons in the PFC by intracellular recording method to assess synaptic plasticity in the form of long-term potentiation (LTP). We also performed N-methyl-d-aspartate acid (NMDA) receptor binding assay in the PFC and hippocampus using radiolabeled NMDA receptor antagonist [
3 H]MK-801., Results: Theta-burst stimulation induced LTP in the PFC of genetic control, WKY/Ezo, whereas failed to induce LTP in that of SHRSP/Ezo. The Kd value of [3 H]MK-801 binding for NMDA receptors in the PFC of SHRSP/Ezo was higher than in the WKY/Ezo. Neither the Bmax nor Kd of [3 H]MK-801 binding in the SHRSP/Ezo hippocampus was significantly different to WKY/Ezo., Conclusion: These results suggest that the AD/HD animal model SHRSP/Ezo has NMDA receptor dysfunction in the PFC., (© 2018 The Authors. Neuropsychopharmacology Reports published by John Wiley & Sons Australia, Ltd on behalf of The Japanese Society of Neuropsychopharmacology.)- Published
- 2018
- Full Text
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45. Effects of the Nonsteroidal Anti-inflammatory Drug Celecoxib on Mitochondrial Function.
- Author
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Tatematsu Y, Fujita H, Hayashi H, Yamamoto A, Tabata A, Nagamune H, and Ohkura K
- Subjects
- Aldehyde Dehydrogenase, Mitochondrial metabolism, Animals, Cell Membrane Permeability drug effects, Dose-Response Relationship, Drug, Electron Transport drug effects, Erythrocytes drug effects, Hydroxymethylglutaryl-CoA Synthase metabolism, In Vitro Techniques, Male, Mitochondria, Liver drug effects, Mitochondrial Swelling drug effects, Oxygen Consumption drug effects, Rats, Rats, Wistar, Anti-Inflammatory Agents, Non-Steroidal pharmacology, Celecoxib pharmacology, Cyclooxygenase 2 Inhibitors pharmacology, Mitochondria drug effects
- Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used to treat inflammation and pain. In the present study, we examined the effects of celecoxib, a cyclooxygenase-2 (COX-2)-selective NSAID, on rat liver mitochondrial function. Celecoxib dose-dependently induced mitochondria swelling, which was not suppressed by cyclosporine A (CsA). The oxygen consumption rate in mitochondria-suspended solution was facilitated by the addition of celecoxib, and its uncoupling activity was observed. Celecoxib also suppressed SF6847-induced uncoupling, and appeared to exert inhibitory effects on the electron transport chain. Celecoxib suppressed the state 3 oxygen consumption rate in the presence of ADP. Protein release from the mitochondrial matrix was detected following the addition of celecoxib, and aldehyde dehydrogenase 2 (ALDH2) and hydroxymethylglutaryl-CoA (HMG-CoA) synthase 2 (HMGCS2) bands were confirmed in a Western blot analysis. On the other hand, protein release of cytochrome C (CytC), which is an inducer of apoptosis, from the intermembrane space was not observed. Celecoxib enhanced the membrane permeability of human erythrocytes and synthesized liposomes dose-dependently. It then induced the membrane-involving mitochondrial swelling and suppressed mitochondrial function.
- Published
- 2018
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46. Interactive Analysis of TX-1123 with Cyclo-oxygenase: Design of COX2 Selective TX Analogs.
- Author
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Ohkura K, Tatematsu Y, Kawaguchi Y, Uto Y, and Hori H
- Subjects
- Binding Sites, Celecoxib pharmacology, Cyclooxygenase 1 chemistry, Cyclooxygenase 2 chemistry, Cysteine metabolism, Glutamine metabolism, Humans, Models, Molecular, Molecular Docking Simulation, Protein Binding, Benzylidene Compounds pharmacology, Cyclooxygenase 1 metabolism, Cyclooxygenase 2 metabolism, Cyclopentanes pharmacology
- Abstract
Background: To date, two cyclo-oxygenase (COX) isoforms, COX1 and COX2, have been identified. In the present study, the COX-inhibitory activities of TX-1123 derivatives with the 2-hydroxyarylidene-4-cyclopentene-1,3-dione structure were examined, and the binding profiles of TX-1123 to COXs were analyzed using docking simulations., Materials and Methods: X-Ray data on COX1 [protein data bank (PDB) ID=1PGG] and COX2 (PDB ID=3LN1) were used for molecular interactive simulations. The interactive profiles of TX-1123 derivatives with COXs were examined using a molecular simulation technique with Molegro Virtual Docker (CLC bio, Aarhus, Denmark)., Results: TX-1123 exhibited COX1-inhibitory activity [half-maximal-inhibitory concentration (IC
50 )=1.57×10-5 M]. The COX2 inhibitory activity of TX-1123 was potent (IC50 =1.16×10-6 M), and the ratio of COX1/COX2 inhibition was 13.5. TX-1123 bound to the COX2 molecule, and the oxygen atom of the 4-cyclopentene-1,3-dione region of TX-1123 interacted with Cys26 and Gln447 of COX2., Conclusion: The TX-1123-binding pocket of COX2 differs from that of the COX2-selective celecoxib-binding pocket. TX-1123 exhibited a different COX2-interactive mechanism from that of celecoxib., (Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)- Published
- 2017
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47. The Thymidine Phosphorylase Imaging Agent 123I-IIMU Predicts the Efficacy of Capecitabine.
- Author
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Kobashi N, Matsumoto H, Zhao S, Meike S, Okumura Y, Abe T, Akizawa H, Ohkura K, Nishijima K, Tamaki N, and Kuge Y
- Subjects
- Animals, Capecitabine pharmacokinetics, Cell Line, Tumor, Colonic Neoplasms diagnostic imaging, Female, Humans, Male, Mice, Mice, Inbred BALB C, Mice, Nude, Molecular Imaging methods, Prognosis, Reproducibility of Results, Sensitivity and Specificity, Treatment Outcome, 5'-Nucleotidase metabolism, Capecitabine therapeutic use, Colonic Neoplasms drug therapy, Colonic Neoplasms enzymology, Drug Monitoring methods, Single Photon Emission Computed Tomography Computed Tomography methods
- Abstract
Unlabelled: Recently, companion diagnostics with nuclear medicine techniques have been anticipated as more suitable means than biopsy for predicting treatment efficacy. The anticancer effect of capecitabine, an orally administered chemotherapeutic agent activated by thymidine phosphorylase (TP), is positively associated with tumor TP expression levels. This study aimed to assess whether TP imaging using a radiolabeled uracil derivative, (123)I-5-iodo-6-[(2-iminoimidazolidinyl)methyl]uracil ((123)I-IIMU), could predict the efficacy of capecitabine treatment., Methods: Sensitivity to doxifluridine, a metabolite of capecitabine and direct substrate for TP, was assessed by water-soluble tetrazolium salt assays in vitro for 3 human colon cancer cell lines with different TP expression profiles. The intracellular uptake and retention of (123)I-IIMU were evaluated. Mice inoculated with each cell line were treated with capecitabine for 2 wk, and tumor growth was compared. In vivo distribution studies and SPECT/CT imaging of (123)I-IIMU were performed in inoculated mice., Results: In vitro experiments showed a positive relation between TP expression levels and doxifluridine sensitivity. In vitro studies revealed that intracellular uptake and retention of (123)I-IIMU were dependent on TP expression levels. In vivo experiments in inoculated mice showed that (123)I-IIMU accumulation in tumor tissue was in line with TP expression levels and susceptibility to capecitabine treatment. Moreover, SPECT/CT imaging of (123)I-IIMU in tumor-inoculated mice showed that (123)I-IIMU reflects TP expression levels in tumor tissues., Conclusion: (123)I-IIMU could be used as an in vivo companion diagnostic for predicting the efficacy of capecitabine treatment., (© 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)
- Published
- 2016
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48. An Antitumor 2-Hydroxyarylidene-4-cyclopentene-1,3-Dione as a Protein Tyrosine Kinase Inhibitor: Interaction Between TX-1123 Derivatives and Src Kinase.
- Author
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Ohkura K, Kawaguchi Y, Tatematsu Y, Uto Y, and Hori H
- Subjects
- Binding Sites, Drug Screening Assays, Antitumor, Humans, Models, Molecular, Protein Binding, src-Family Kinases chemistry, Antineoplastic Agents chemistry, Benzylidene Compounds chemistry, Cyclopentanes chemistry, Protein Kinase Inhibitors chemistry, src-Family Kinases antagonists & inhibitors
- Abstract
Background: Protein tyrosine kinases (PTKs) play major roles in signal transduction during cell proliferation and apoptosis. Tyrphostin AG17 was previously shown to be a potent tumor growth inhibitor, while AG17 induced apoptosis and inhibited activity of cyclin-dependent kinase 2. We herein describe the binding features of tyrphostin AG17 analogs, such as TX-1123, with Src kinase (Src-K)., Materials and Methods: Structural data for Src-K were obtained from a protein data bank (ID=2SRC), and the molecular interactions between Src-K and TX-1123 derivatives were examined., Results: TX-1123 exihibited potent Src-K inhibitory activity (half maximal-inhibitory concentration=2.2 μM), and fit into the pocket of the Src-K molecule as well as c-AMP did., Conclusion: The binding profiles of TX-1123 derivatives differed from each other, while their Src-K inhibitory activities were affected by their fit in the Src-K molecule., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)
- Published
- 2016
49. Transesophageal versus transcranial motor evoked potentials to monitor spinal cord ischemia.
- Author
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Tsuda K, Shiiya N, Takahashi D, Ohkura K, Yamashita K, Kando Y, and Arai Y
- Subjects
- Animals, Disease Models, Animal, Dogs, Neurologic Examination, Reaction Time, Spinal Cord Ischemia physiopathology, Time Factors, Esophagus innervation, Evoked Potentials, Motor, Muscle, Skeletal innervation, Spinal Cord physiopathology, Spinal Cord Ischemia diagnosis, Transcranial Direct Current Stimulation
- Abstract
Objectives: We have previously reported that transesophageal motor evoked potential is feasible and more stable than transcranial motor evoked potential. This study aimed to investigate the efficacy of transesophageal motor evoked potential to monitor spinal cord ischemia., Methods: Transesophageal and transcranial motor evoked potentials were recorded in 13 anesthetized dogs at the bilateral forelimbs, anal sphincters, and hindlimbs. Spinal cord ischemia was induced by aortic balloon occlusion at the 8th to 10th thoracic vertebra level. In the 12 animals with motor evoked potential disappearance, occlusion was maintained for 10 minutes (n = 6) or 40 minutes (n = 6) after motor evoked potential disappearance. Neurologic function was evaluated by Tarlov score at 24 and 48 hours postoperatively., Results: Time to disappearance of bilateral motor evoked potentials was quicker in transesophageal motor evoked potentials than in transcranial motor evoked potentials at anal sphincters (6.9 ± 3.1 minutes vs 8.3 ± 3.4 minutes, P = .02) and hindlimbs (5.7 ± 1.9 minutes vs 7.1 ± 2.7 minutes, P = .008). Hindlimb function was normal in all dogs in the 10-minute occlusion group, and motor evoked potentials recovery (>75% on both sides) after reperfusion was quicker in transesophageal motor evoked potentials than transcranial motor evoked potentials at hindlimbs (14.8 ± 5.6 minutes vs 24.7 ± 8.2 minutes, P = .001). At anal sphincters, transesophageal motor evoked potentials always reappeared (>25%), but transcranial motor evoked potentials did not in 3 of 6 dogs. In the 40-minute occlusion group, hindlimb motor evoked potentials did not reappear in 4 dogs with paraplegia. Among the 2 remaining dogs, 1 with paraparesis (Tarlov 3) showed delayed recovery (>75%) of hindlimb motor evoked potentials without reappearance of anal sphincter motor evoked potentials. In another dog with spastic paraplegia, transesophageal motor evoked potentials from the hindlimbs remained less than 20%, whereas transcranial motor evoked potentials showed recovery (>75%)., Conclusions: Transesophageal motor evoked potentials may be superior to transcranial motor evoked potentials in terms of quicker response to spinal cord ischemia and better prognostic value., (Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)
- Published
- 2016
- Full Text
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50. Effect of N-Phenylanthranilic Acid Scaffold Nonsteroidal Anti-inflammatory Drugs on the Mitochondrial Permeability Transition.
- Author
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Tatematsu Y, Hayashi H, Taguchi R, Fujita H, Yamamoto A, and Ohkura K
- Subjects
- Animals, Anti-Inflammatory Agents, Non-Steroidal chemistry, Electron Transport drug effects, Male, Mitochondria, Liver metabolism, Molecular Structure, Nitriles pharmacology, Oxygen Consumption drug effects, Rats, Rats, Wistar, Anti-Inflammatory Agents, Non-Steroidal chemical synthesis, Mitochondria, Liver drug effects, ortho-Aminobenzoates chemistry
- Abstract
Hepatotoxicity is a known side effect of nonsteroidal anti-inflammatory drugs (NSAIDs). In the present study, the effects of N-phenylanthranilic acid (NPA) scaffold NSAIDs on rat liver mitochondria were examined. Mefenamic acid (MEF, 200 µM) induced mitochondrial swelling, which was inorganic phosphate (Pi)-dependent and suppressed by cyclosporin A (CsA, 2.5 µM), similar to calcium-induced swelling. Mitochondrial swelling was also observed following the addition of 200 µM flufenamic acid (FLU), meclofenamic acid (MCL), and tolfenamic acid (TOL). Less swelling was observed with the addition of 200 µM diclofenac (DIC) or NPA. Diphenylamine (DPA)-induced swelling occurred in a Pi-independent manner and was not sensitive to CsA. The mechanism by which DPA interacted with the mitochondrial inner membrane differed from those of the other NPA scaffold NSAIDs. The addition of 50 µM MEF, MCL, TOL, and FLU had uncoupling effects in mitochondrial inner membrane. These NSAIDs dose-dependently obstructed electron transport in the respiratory chain. NSAIDs are known to have various dynamic structures, and the solvation free energies (dGWs: an index of stereo-hydrophobicity) of the conformers obtained were determined using a molecular orbital analysis. The relationship between the dynamic structures and swelling induced by NPA scaffold NSAIDs was also examined.
- Published
- 2016
- Full Text
- View/download PDF
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