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Search Results: 1 - 10 of 999 matches for " Toshiyuki Matsunaga "
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Aldo–Keto Reductase 1B10 and Its Role in Proliferation Capacity of Drug-Resistant Cancers
Toshiyuki Matsunaga,Midori Soda
Frontiers in Pharmacology , 2012, DOI: 10.3389/fphar.2012.00005
Abstract: The human aldo–keto reductase AKR1B10, originally identified as an aldose reductase-like protein and human small intestine aldose reductase, is a cytosolic NADPH-dependent reductase that metabolizes a variety of endogenous compounds, such as aromatic and aliphatic aldehydes and dicarbonyl compounds, and some drug ketones. The enzyme is highly expressed in solid tumors of several tissues including lung and liver, and as such has received considerable interest as a relevant biomarker for the development of those tumors. In addition, AKR1B10 has been recently reported to be significantly up-regulated in some cancer cell lines (medulloblastoma D341 and colon cancer HT29) acquiring resistance toward chemotherapeutic agents (cyclophosphamide and mitomycin c), suggesting the validity of the enzyme as a chemoresistance marker. Although the detailed information on the AKR1B10-mediated mechanisms leading to the drug resistance process is not well understood so far, the enzyme has been proposed to be involved in functional regulations of cell proliferation and metabolism of drugs and endogenous lipids during the development of chemoresistance. This article reviews the current literature focusing mainly on expression profile and roles of AKR1B10 in the drug resistance of cancer cells. Recent developments of AKR1B10 inhibitors and their usefulness in restoring sensitivity to anticancer drugs are also reviewed.
Effects of Nozzle-Lip Length on Reduction of Transonic Resonance in 2D Supersonic Nozzle  [PDF]
Seoungyoung Shin, Akira Matsunaga, Hiroyuki Marubayashi, Toshiyuki Aoki
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32A011
Abstract: It is known that the transonic resonance takes place, in divergent section of supersonic nozzle, similarly to the longitudinal acoustic resonance of a conical section with one end closed and the other end open. And the conical section is similar to the separation zone between shock wave and nozzle exit in divergent part of supersonic nozzle. The present paper describes an experimental work to investigate a reduction of transonic resonance by change the lip length of 2-Dimensional converging-diverging nozzle. In this study, the nozzle pressure ratio varied in the range between 1.4 and 2.2 as shock-containing flow conditions. And a Schlieren optical system was used to visualize the flow fields. Especially, by using a high-speed video camera, we obtained the shock position at that moment. And acoustic measurements were employed to compare the sound spectra level of each experimental case. And it was found that the transonic resonance was decreased when a large separation zone located at the side, where a nozzle-lip attached to nozzle exit additionally. In this case, the amplitude of shock oscillation and wall static pressure oscillation were also decreased.

 

Oseltamivir Prescription and Regulatory Actions Vis-à-Vis Abnormal Behavior Risk in Japan: Drug Utilization Study Using a Nationwide Pharmacy Database
Hisashi Urushihara, Yuko Doi, Masaru Arai, Toshiyuki Matsunaga, Yosuke Fujii, Naoko Iino, Takashi Kawamura, Koji Kawakami
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028483
Abstract: Background In March 2007, a regulatory advisory was issued in Japan to restrict oseltamivir use in children aged 10-19 years because of safety concerns over abnormal behavior. The effectiveness and validity of regulatory risk minimization actions remain to be reviewed, despite their significant public health implications. To assess the impact of the regulatory actions on prescribing practices and safety reporting. Methodoloy/Prinicpal Findings In this retrospective review of a nationwide pharmacy database, we analyzed 100,344 dispensation records for oseltamivir and zanamivir for the period from November 2006 to March 2009. The time trend in dispensations for these antiviral agents was presented before and after the regulatory actions, contrasted with intensity of media coverage and the numbers of spontaneous adverse reaction reports with regard to antivirals. The 2007 regulatory actions, together with its intense media coverage, reduced oseltamivir dispensation in targeted patients in fiscal year 2008 to 20.4% of that in fiscal year 2006, although influenza activities were comparable between these fiscal years. In contrast, zanamivir dispensation increased approximately nine-fold across all age groups. The number of abnormal behavior reports associated with oseltamivir in children aged 10-19 years decreased from fiscal year 2006 to 2008 (24 to 9 cases); this decline was offset by the increased number of reports of abnormal behavior in children under age 10 (12 to 28 cases). The number of reports associated with zanamivir increased in proportion to increased dispensation of this drug (11 to 114 cases). Conclusions/Significance The 2007 actions effectively reduced oseltamivir prescriptions and the number of reports of abnormal behavior in the targeted group. The observed increase in abnormal behavior reports in oseltamivir patients under age 10 and in zanamivir patients suggests that these patient groups may also be at risk, calling into question the validity of the current discrimination by age and agent (translation is available in Japanese: Appendix S1).
Characteristics of Unsteady Boundary Layer Induced by the Compression Wave Propagating in a Tunnel  [PDF]
Toshiyuki Tanaka, Toshiyuki Aoki
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24A030
Abstract:

A compression wave is generated ahead of a high-speed train, while entering a tunnel. This compression wave propa- gates to the tunnel exit and spouts out as a micro pressure wave, causing an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a compression wave propagating along a tunnel must be understood and experimental information on these phenomena is required. An experimental and numerical in- vestigation is carried out to clarify the mechanism of the propagating compression wave in a tube. The final objective of our study is to understand the mechanism of the attenuation and distortion of propagating compression waves in a tun- nel. In the present paper, experimental investigations are carried out on the transition of the unsteady boundary layer induced by a propagating compression wave in a model tunnel by means of a developed laser differential interferometry technique.

Geographic Variation in Germination Traits in Melia azedarach and Rhaphiolepis umbellata  [PDF]
Tetsuto Abe, Michio Matsunaga
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.21007
Abstract: Some plant species traits may not be uniform across populations distributed across a wide latitudinal range. This study examined intraspecies variation in the effects of cold stratification on the germination of seeds of two widespread trees, Rhaphiolepis umbellata (Rosaceae) and Melia azedarach (Meliaceae), collected from the subtropical Ogasawara Islands (southern seeds) and the temperate Japan mainland (northern seeds). Under the no-treatment control, the southern seeds germinated faster in R. umbellata and achieved a higher germination percentage in M. azedarach. The regional differences in germination performance were reduced by cold stratification. It was reasonable that these germination traits increase fitness under each climate region. Because the remote Ogasawara populations are sufficiently isolated to have developed some distinct characteristics, even common, widespread species may have important conservation value where they exist within insular biota.
The Menu-Induced Core of an Economy with an Excludable Public Good  [PDF]
Toshiyuki Hirai
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.44039
Abstract:

This paper introduces a core concept in an economy with an excludable public good. In the economy, we assume that each coalition is allowed to achieve an allocation via a menu, a kind of a nonlinear price. Our core concept is called the menu-induced core that is defined as the set of allocations achievable by menus that are robust against all coalitional improvements achieved via menus. We show that the menu-induced core is nonempty. We also investigate certain properties of the menu-induced core that show the difference between the menu-induced core and the core defined in a standard way.

A Review of Measurement-Integrated Simulation of Complex Real Flows  [PDF]
Toshiyuki Hayase
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2015, DOI: 10.4236/jfcmv.2015.32006
Abstract: In spite of the inherent difficulty, reproducing the exact structure of real flows is a critically important issue in many fields, such as weather forecasting or feedback flow control. In order to obtain information on real flows, extensive studies have been carried out on methodology to integrate measurement and simulation, for example, the four-dimensional variational data assimilation method (4D-Var) or the state estimator such as the Kalman filter or the state observer. Measurement-integrated (MI) simulation is a state observer in which a computational fluid dynamics (CFD) scheme is used as a mathematical model of the physical system instead of a small dimensional linear dynamical system usually used in state observers. A large dimensional nonlinear CFD model makes it possible to accurately reproduce real flows for properly designed feedback signals. This review article surveys the theoretical formulations and applications of MI simulation. Formulations of MI simulation are presented, including governing equations of a flow field observer, those of a linearized error dynamics describing the convergence of the observer, and stabilization of the numerical scheme, which is important in implementation of MI simulation. Applications of MI simulation are presented ranging from fundamental turbulent flows in pipes and Karman vortices in a wind tunnel to clinical application in diagnosis of blood flows in a human body.
Preconditioned Iterative Method for Regular Splitting  [PDF]
Toshiyuki Kohno
Advances in Pure Mathematics (APM) , 2017, DOI: 10.4236/apm.2017.72009
Abstract: Several preconditioners are proposed for improving the convergence rate of the iterative method derived from splitting. In this paper, the comparison theorem of preconditioned iterative method for regular splitting is proved. And the convergence and comparison theorem for any preconditioner are indicated. This comparison theorem indicates the possibility of finding new preconditioner and splitting. The purpose of this paper is to show that the preconditioned iterative method yields a new splitting satisfying the regular or weak regular splitting. And new combination preconditioners are proposed. In order to denote the validity of the comparison theorem, some numerical examples are shown.
Flows of a Rarefied Gas between Coaxial Circular Cylinders with Nonuniform Surface Properties  [PDF]
Toshiyuki Doi
Open Journal of Fluid Dynamics (OJFD) , 2019, DOI: 10.4236/ojfd.2019.91002
Abstract: Flows of a rarefied gas between coaxial circular cylinders with nonuniform surface properties are studied on the basis of kinetic theory. It is assumed that the outer cylinder is a diffuse reflection boundary and the inner cylinder is a Maxwell-type boundary whose accommodation coefficient varies in the circumferential direction. Three fundamental flows are studied: 1) a flow caused by the rotation of the outer cylinder (Couette flow), 2) a flow induced between the cylinders at rest kept at different temperatures (heat transfer problem), and 3) a flow induced by the circumferential temperature distribution along the cylindrical surfaces (thermal creep flow). The linearized ES-BGK model of the Boltzmann equation is numerically analyzed using a finite difference method. The time-independent behavior of the gas is studied over a wide range of the gas rarefaction degree, the radii ratio, and a parameter characterizing the distribution of the accommodation coefficient. Due to an effect of nonuniform surface properties, a local heat transfer occurs between the gas and the cylindrical surfaces in Couette flow; a local tangential stress arises in the heat transfer problem. However, the total heat transfer between the two cylinders in Couette flow and the total torque acting on the inner cylinder in the heat transfer problem vanish irrespective of the flow parameters. Two nondegenerate reciprocity relations arise due to the effect of nonuniform surface properties. The reciprocity relations among the above-mentioned three flows are numerically confirmed over a wide range of the flow parameters. The force on the inner cylinder, which also arises due to the effect of nonuniform surface properties in Couette flow and the heat transfer problems, is studied.
The Influence of Free 3-Nitrotyrosine and Saliva on the Quantitative Analysis of Protein-Bound 3-Nitrotyrosine in Sputum
Kazuhito Ueshima, Yoshiaki Minakata, Hisatoshi Sugiura, Satoru Yanagisawa, Tomohiro Ichikawa, Keiichirou Akamatsu, Tsunahiko Hirano, Masanori Nakanishi, Kazuto Matsunaga, Toshiyuki Yamagata and Masakazu Ichinose
Analytical Chemistry Insights , 2012,
Abstract: : Background: We have recently developed a new technique for quantitatively measuring protein-bound 3-nitrotyrosine (3-NT), a footprint of nitrosative stress, utilizing high-performance liquid chromatography with an electrochemical detection (HPLC-ECD) system. Using this system, we showed that 3-NT formation was upregulated in the sputum of both COPD and asthmatic patients. However, in order to improve the accuracy of the measurement system. We have to resolve some problems which were the influence of free amino acid form of 3-NT and of salivary contamination. Objectives: We initially investigated the amount of the free amino acid form of 3-NT in induced sputum and compared with that of protein-bound 3-NT. Next, we evaluated the concentration of protein-bound 3-NT in saliva and compared with that in induced sputum by means of HPLC-ECD. Methods: Five male COPD patients were enrolled. Induced sputum and saliva were obtained from the patients. The free amino acid form of 3-NT in sputum and saliva was measured by HPLC-ECD, and the protein-bound 3-NT and tyrosine in sputum and saliva were enzymatically hydrolyzed by Streptomyces griseus Pronase and measured for the protein hydrolysate by HPLC-ECD. Results: The mean value of the amount of protein-bound 3-NT was 65.0 fmol (31.2 to 106.4 fmol). On the other hand, the amount of the free amino acid form of 3-NT was under the detection limit (<10 fmol). The levels of both 3-NT (sputum: 0.55 ± 0.15 pmol/ml, saliva: 0.02 ± 0.01 pmol/ml, p < 0.01) and tyrosine (sputum: 0.81 ± 0.43 μmol/ml, saliva: 0.07 ± 0.04 μmol/ml, p < 0.01) in saliva were significantly lower than in sputum. The percentage of 3-NT in saliva to that in sputum was about 3.1%, and that of tyrosine was about 9.0%. Conclusion: The free amino acid form of 3-NT does not affect the measurement of protein-bound 3-NT. Furthermore, the influence of salivary contamination on the measurement of protein-bound 3-NT in induced sputum by means of HPLC-ECD was very small and could be negligible.
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