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Search Results: 1 - 10 of 495 matches for " Mitsuhiro Ohshima "
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An Integrated Expression Profiling Reveals Target Genes of TGF-β and TNF-α Possibly Mediated by MicroRNAs in Lung Cancer Cells
Akira Saito, Hiroshi I. Suzuki, Masafumi Horie, Mitsuhiro Ohshima, Yasuyuki Morishita, Yoshimitsu Abiko, Takahide Nagase
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0056587
Abstract: EMT (epithelial-mesenchymal transition) is crucial for cancer cells to acquire invasive phenotypes. In A549 lung adenocarcinoma cells, TGF-β elicited EMT in Smad-dependent manner and TNF-α accelerated this process, as confirmed by cell morphology, expression of EMT markers, capacity of gelatin lysis and cell invasion. TNF-α stimulated the phosphorylation of Smad2 linker region, and this effect was attenuated by inhibiting MEK or JNK pathway. Comprehensive expression analysis unraveled genes differentially regulated by TGF-β and TNF-α, such as cytokines, chemokines, growth factors and ECM (extracellular matrices), suggesting the drastic change in autocrine/paracrine signals as well as cell-to-ECM interactions. Integrated analysis of microRNA signature enabled us to identify a subset of genes, potentially regulated by microRNAs. Among them, we confirmed TGF-β-mediated induction of miR-23a in lung epithelial cell lines, target genes of which were further identified by gene expression profiling. Combined with in silico approaches, we determined HMGN2 as a downstream target of miR-23a. These findings provide a line of evidence that the effects of TGF-β and TNF-α were partially mediated by microRNAs, and shed light on the complexity of molecular events elicited by TGF-β and TNF-α.
Derivative of a Determinant with Respect to an Eigenvalue in the LDU Decomposition of a Non-Symmetric Matrix  [PDF]
Mitsuhiro Kashiwagi
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.43069
Abstract:

We demonstrate that, when computing the LDU decomposition (a typical example of a direct solution method), it is possible to obtain the derivative of a determinant with respect to an eigenvalue of a non-symmetric matrix. Our proposed method augments an LDU decomposition program with an additional routine to obtain a program for easily evaluating the derivative of a determinant with respect to an eigenvalue. The proposed method follows simply from the process of solving simultaneous linear equations and is particularly effective for band matrices, for which memory requirements are significantly reduced compared to those for dense matrices. We discuss the theory underlying our proposed method and present detailed algorithms for implementing it.

Derivative of a Determinant with Respect to an Eigenvalue in the Modified Cholesky Decomposition of a Symmetric Matrix, with Applications to Nonlinear Analysis  [PDF]
Mitsuhiro Kashiwagi
American Journal of Computational Mathematics (AJCM) , 2014, DOI: 10.4236/ajcm.2014.42009
Abstract:

In this paper, we obtain a formula for the derivative of a determinant with respect to an eigenvalue in the modified Cholesky decomposition of a symmetric matrix, a characteristic example of a direct solution method in computational linear algebra. We apply our proposed formula to a technique used in nonlinear finite-element methods and discuss methods for determining singular points, such as bifurcation points and limit points. In our proposed method, the increment in arc length (or other relevant quantities) may be determined automatically, allowing a reduction in the number of basic parameters. The method is particularly effective for banded matrices, which allow a significant reduction in memory requirements as compared to dense matrices. We discuss the theoretical foundations of our proposed method, present algorithms and programs that implement it, and conduct numerical experiments to investigate its effectiveness.

A New Analysis Concept in Applying Software Reliability Growth Models and Tool Implementation: The SafeMan  [PDF]
Takaji Fujiwara, Mitsuhiro Kimura
Journal of Software Engineering and Applications (JSEA) , 2014, DOI: 10.4236/jsea.2014.75036
Abstract:

In recent years, many software development organizations have been assessing and analyzing their software product’s reliability/quality and judging whether the software product is releasable by using Software Reliability Growth Models (SRGMs) at the final stage of software development. The usage of SRGMs originates in the advantage that various reliability analysis results based on the SRGMs can be acquired easily. However, it is very difficult for general software project managers to grasp the achievement level of reliability/quality based on its analysis results because some sort of professional knowledge is required in order to understand the information on the attainment progress of software product’s reliability/quality. Moreover, it is also difficult for software project managers and inspectors who do not deeply comprehend the details of their project to evaluate the degree of software reliability and quality, if they assess it without grasping the live development situation and only see the documents submitted from their staff. In this paper, we propose a new analysis concept for assessing the software product’s reliability/quality, and illustrate the output results obtained by a tool, the SafeMan.

Ownership or Taking Action: Which Is More Important for Happiness?  [PDF]
Kohji Hayase, Mitsuhiro Ura
Psychology (PSYCH) , 2015, DOI: 10.4236/psych.2015.66072
Abstract: In two studies (2010 and 2011), more than 2000 respondents living in Japan were asked whether they gained more happiness from ownership or from taking action. In the 2010 study, many more individuals preferred taking action to ownership; this preference was greater in women than in men and in older people than in younger people. Reasons for this preference were plainly ex-pressed in respondents’ free writing, and a categorical distinction between ownership and taking action was readily recognized and widely shared. Social desirability concerns probably did not play a role in responses. In the 2011 study, many individuals valued action more than ownership as like as the 2010 study. The preference for taking action over ownership was greater in women than in men, in older people than in younger people, and in people with higher levels of education than in people with lower levels of education. There was no relationship with annual income. The correlations with gender and level of education were similar to results of comparable studies conducted in the USA, although in the US studies, experiential purchases were evaluated, rather than taking action; however, the correlation with age was uncertain in the US studies. Further studies with US respondents will be necessary to examine this correlation. Possible reasons why many more people preferred happiness gained from taking action to happiness experienced from ownership were discussed.
Production Smoothing in Developed Countries  [PDF]
Isamu Ginama, Mitsuhiro Odaki
Journal of Mathematical Finance (JMF) , 2017, DOI: 10.4236/jmf.2017.72018
Abstract: This paper extends the method of regressing production and sales variables on a set of seasonal dummy variables and a linear trend for empirical tests on the production smoothing hypothesis of inventory investment. Unit root testing procedures form the basis for constructing the bootstrap confidence intervals for the ratio of the variance of production to the variance of sales. Models used to test for a unit root when there are structural breaks in the linear time trend are converted to equations comprising deterministic and stochastic components. A limiting distribution of the test statistic is derived. Bootstrap resampling is conducted over deterministic parts of the converted equations to construct confidence intervals for the relative variance ratio for G7 countries. Primary findings for these countries are production-counter smoothing phenomena.
Centrosome Aberrations Associated with Cellular Senescence and p53 Localization at Supernumerary Centrosomes
Susumu Ohshima
Oxidative Medicine and Cellular Longevity , 2012, DOI: 10.1155/2012/217594
Abstract: Centrosome overduplication or amplification has been observed in many human cancers and in premalignant tissue, but the mechanisms leading to such centrosome aberrations are not fully understood. We previously showed that abnormal mitotic cells with supernumerary centrosomes increase with replicative senescence in human fibroblasts, especially in a polyploid subpopulation. This study examines localization of p53 protein at centrosomes in mitotic cells, which is often observed in association with DNA damage response, to investigate a possible association between p53 localization and numerical centrosome aberrations induced by cellular senescence. Cultures at later passages or the 4th day after exposure to H2O2 showed increased frequencies of mitotic cells with supernumerary centrosomes, especially in a polyploid subpopulation. Immunohistochemical analysis frequently showed p53-positive foci in mitotic cells, and some were localized at centrosomes. The number of p53-positive foci in mitotic cells and its localization to centrosomes increased with replicative and premature senescence. Supernumerary centrosomes showed higher frequencies of p53 localization compared to normally duplicated centrosomes. Centrosome-associated p53 protein was phosphorylated at Ser15. These data suggest a possible association between localization of p53 protein and numerical centrosome aberrations in replicatively or prematurely senescent cells.
Discovery of the 2001 outburst of wz sagittae
T. Ohshima
Revista mexicana de astronomía y astrofísica , 2004,
Abstract:
Theory of electrostatics and electrokinetics of soft particles
Hiroyuki Ohshima
Science and Technology of Advanced Materials , 2009,
Abstract: We investigate theoretically the electrostatics and electrokinetics of a soft particle, i.e. a hard particle covered with an ion-penetrable surface layer of polyelectrolytes. The electric properties of soft particles in an electrolyte solution, which differ from those of hard particles, are essentially determined by the Donnan potential in the surface layer. In particular, the Donnan potential plays an essential role in the electrostatics and electrokinetics of soft particles. Furthermore, the concept of zeta potential, which is important in the electrokinetics of hard particles, loses its physical meaning in the electrokinetics of soft particles. In this review, we discuss the potential distribution around a soft particle, the electrostatic interaction between two soft particles, and the motion of a soft particle in an electric field.
Centrosome Aberrations Associated with Cellular Senescence and p53 Localization at Supernumerary Centrosomes
Susumu Ohshima
Oxidative Medicine and Cellular Longevity , 2012, DOI: 10.1155/2012/217594
Abstract: Centrosome overduplication or amplification has been observed in many human cancers and in premalignant tissue, but the mechanisms leading to such centrosome aberrations are not fully understood. We previously showed that abnormal mitotic cells with supernumerary centrosomes increase with replicative senescence in human fibroblasts, especially in a polyploid subpopulation. This study examines localization of p53 protein at centrosomes in mitotic cells, which is often observed in association with DNA damage response, to investigate a possible association between p53 localization and numerical centrosome aberrations induced by cellular senescence. Cultures at later passages or the 4th day after exposure to H2O2 showed increased frequencies of mitotic cells with supernumerary centrosomes, especially in a polyploid subpopulation. Immunohistochemical analysis frequently showed p53-positive foci in mitotic cells, and some were localized at centrosomes. The number of p53-positive foci in mitotic cells and its localization to centrosomes increased with replicative and premature senescence. Supernumerary centrosomes showed higher frequencies of p53 localization compared to normally duplicated centrosomes. Centrosome-associated p53 protein was phosphorylated at Ser15. These data suggest a possible association between localization of p53 protein and numerical centrosome aberrations in replicatively or prematurely senescent cells. 1. Introduction Centrosome overduplication or centrosome amplification has been observed in many human cancers and in premalignant tissue [1–5]. Centrosome aberrations have been linked to genomic instability during tumour progression, because centrosomes dysfunction may cause abnormal spindle assembly and chromosome missegregation, leading to chromosome aneuploidy [1, 3, 5]. Some studies showed that genetic manipulations that cause centrosome amplification in vivo can induce tumor development [6, 7]. The mechanisms leading to centrosome aberrations have been studied extensively but still are not fully understood. However, DNA damage-induced centrosome aberrations such as inactivation, amplification, or fragmentation have been reported. For example, inhibitors of DNA replication such as aphidicolin or hydroxyurea cause centrosome inactivation or centrosome splitting, leading to spindle defects [8–10]. Deficiency of Rad51 recombinase, which is essential for DNA repair, causes supernumerary centrosomes [11]. Radiation causes centrosome amplification in tumour cells and in p53-inactivated or ATR-deficient human cells [12–14]. Several studies
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