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Search Results: 1 - 10 of 803 matches for " Hirofumi Hirai "
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Interaction of Helicobacter pylori Cell Membrane with Non-Esterified Cholesterol and Other Steroids  [PDF]
Hirofumi Shimomura, Kouichi Hosoda, Yoshikazu Hirai
Open Journal of Medical Microbiology (OJMM) , 2013, DOI: 10.4236/ojmm.2013.31011
Abstract: Helicobacter pylori performs the unique action of assimilating exogenous non-esterified cholesterol into its cell membrane. This bacterium aggressively incorporates non-esterified cholesterol into the membrane, induces its glucosylation, and uses both non-esterified cholesterol and glucosylated cholesterols as membrane lipid compositions. The reason for this assimilation of non-esterified cholesterol into the cell membrane of H. pylori has eluded investigators for many years. Recent hypotheses posit that the sterol-uptake and sterol-glucosylation contribute to the survival of H. pylori cells in different ways. The incorporation of the non-esterified cholesterol into the cell membrane fortifies the resistance of H. pylori against the antibacterial actions of phosphatidylcholines, antibiotics, and bile salts. In parallel, the glucosylation of the non-esterified cholesterol incorporated into the cell membrane serves H. pylori in two ways. First, it helps the bacterium evade host immune responses, such as phagocytosis by macrophages and activation of antigen-specific T cells. Second, it detoxifies sterols fatal to the bacterium via a novel action of sterol glucosylation recently described in another report from our group. The reluctance of H. pylori to absorb esterified cholesterol remains unexplained. A recent study by our group has demonstrated that the phosphatidylethanolamine (PE) in the outer membrane of H. pylori serves as a steroid-binding lipid the incorporation of non-esterified cholesterol into the membrane. We have also discovered that the myristic acid (C14:0) molecule attached to the PE of this bacterium plays an important role in the selective binding of non-esterified cholesterol but not esterified cholesterol.
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 New Omics Data Resource of Pleurocybella porrigens for Gene Discovery
Tomohiro Suzuki, Kaori Igarashi, Hideo Dohra, Takumi Someya, Tomoyuki Takano, Kiyonori Harada, Saori Omae, Hirofumi Hirai, Kentaro Yano, Hirokazu Kawagishi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069681
Abstract: Background Pleurocybella porrigens is a mushroom-forming fungus, which has been consumed as a traditional food in Japan. In 2004, 55 people were poisoned by eating the mushroom and 17 people among them died of acute encephalopathy. Since then, the Japanese government has been alerting Japanese people to take precautions against eating the P. porrigens mushroom. Unfortunately, despite efforts, the molecular mechanism of the encephalopathy remains elusive. The genome and transcriptome sequence data of P. porrigens and the related species, however, are not stored in the public database. To gain the omics data in P. porrigens, we sequenced genome and transcriptome of its fruiting bodies and mycelia by next generation sequencing. Methodology/Principal Findings Short read sequences of genomic DNAs and mRNAs in P. porrigens were generated by Illumina Genome Analyzer. Genome short reads were de novo assembled into scaffolds using Velvet. Comparisons of genome signatures among Agaricales showed that P. porrigens has a unique genome signature. Transcriptome sequences were assembled into contigs (unigenes). Biological functions of unigenes were predicted by Gene Ontology and KEGG pathway analyses. The majority of unigenes would be novel genes without significant counterparts in the public omics databases. Conclusions Functional analyses of unigenes present the existence of numerous novel genes in the basidiomycetes division. The results mean that the omics information such as genome, transcriptome and metabolome in basidiomycetes is short in the current databases. The large-scale omics information on P. porrigens, provided from this research, will give a new data resource for gene discovery in basidiomycetes.
Solvent-Induced Phase-Inversion and Electrical Actuation of Dielectric Copolymer Films  [PDF]
Yeonju Jang, Toshihiro Hirai
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.23023
Abstract: Block copolymers posses inherently the ability of form a variety of phase-separated microdomain structures. The lengths of block segments and the selectivity of the solvent are primary factors affecting the resultant morphology. This paper investigated the effect of casting solvents on the morphologies and electrical actuation of poly(methyl methacrylate)-poly(n-butyl acrylate)-poly(methyl methacrylate) (PMMA-PnBA-PMMA) triblock copolymer films comprising PMMA hard segment and PnBA soft segment. Transmission electron microscopy and confocal laser scanning microscopy observation revealed that PMMA and PnBA segments were assembled into various micro- and nano-sized phase structures where either of them formed continuous phase. This implies that continous phase could be inversed by used casting solvents. Solvent-dependent phase morphologies had a significant effect on the electrical actuation results. Increase of the PnBA contents and the continuous phases of PnBA soft segments improved both of electrical actuation and dielectric constant, indicating that solvent-induced phase separation modulates the electrical actuation of dielectric films. The significance of the role of solvent selectivity and the major continuous phase of the polymer in defining the morphology and electrical actuation of the self-assembled block copolymer structure are discussed.
Distinct Transforming Activity of ABL Family Tyrosine Kinase Oncogenes Is Induced by Their C-Terminal Domain*  [PDF]
Keiko Okuda, Hideyo Hirai
Open Journal of Blood Diseases (OJBD) , 2013, DOI: 10.4236/ojbd.2013.33A005
Abstract: The TEL/ARG oncogene is similar in structure to the TEL/ABL fusion found in human leukemia, however, we have demonstrated previously that the expression of TEL/ARG in Ba/F3 cells does not sustain strong activity of proliferation, whereas, that of TEL/ABL appeared to induce immediate cell proliferation. To study the molecular basis of the difference in the transforming activity of TEL/ARG and TEL/ABL, TEL/ARG mutants that swapped the kinase domain or C-terminus of ARG with the corresponding domain in ABL were generated, and each mutant was expressed in Ba/F3 cells. A TEL/ARG mutant containing the ABL kinase domain was similar to TEL/ARG in this study, but replacing the ARG C-terminal domain with that of ABL resulted in accelerated proliferation that was similar to that of TEL/ABL. When expressed in primary mouse bone marrow cells by retroviral transduction, spontaneous colony formation in methylcellulose culture was observed, in a fashion dependent on the C-terminal portion of ABL. These results indicate that distinct bio-phenotypes associated with these oncogenes are likely to be regulated by their C-termini, and the C-terminus of ARG contains a functional subdomain that impairs the growth signal induced by ABL family tyrosine kinase.
Longitudinal Study of Spatially Heterogeneous Emphysema Progression in Current Smokers with Chronic Obstructive Pulmonary Disease
Naoya Tanabe, Shigeo Muro, Susumu Sato, Shiro Tanaka, Tsuyoshi Oguma, Hirofumi Kiyokawa, Tamaki Takahashi, Daisuke Kinose, Yuma Hoshino, Takeshi Kubo, Toyohiro Hirai, Michiaki Mishima
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044993
Abstract: Background Cigarette smoke is the main risk factor for emphysema, which is a key pathology in chronic obstructive pulmonary disease (COPD). Low attenuation areas (LAA) in computed tomography (CT) images reflect emphysema, and the cumulative size distribution of LAA clusters follows a power law characterized by the exponent D. This property of LAA clusters can be explained by model simulation, where mechanical force breaks alveolar walls causing local heterogeneous lung tissue destruction. However, a longitudinal CT study has not investigated whether continuous smoking causes the spatially heterogeneous progression of emphysema. Methods We measured annual changes in ratios of LAA (LAA%), D and numbers of LAA clusters (LAN) in CT images acquired at intervals of ≥3 years from 22 current and 31 former smokers with COPD to assess emphysema progression. We constructed model simulations using CT images to morphologically interpret changes in current smokers. Results D was decreased in current and former smokers, whereas LAA% and LAN were increased only in current smokers. The annual changes in LAA%, D, and LAN were greater in current, than in former smokers (1.03 vs. 0.37%, p = 0.008; ?0.045 vs. ?0.01, p = 0.004; 13.9 vs. 1.1, p = 0.007, respectively). When LAA% increased in model simulations, the coalescence of neighboring LAA clusters decreased D, but the combination of changes in D and LAN in current smokers could not be explained by the homogeneous emphysema progression model despite cluster coalescence. Conversely, a model in which LAAs heterogeneously increased and LAA clusters merged somewhat in relatively advanced emphysematous regions could reflect actual changes. Conclusions Susceptibility to parenchymal destruction induced by continuous smoking is not uniform over the lung, but might be higher in local regions of relatively advanced emphysema. These could result in the spatially heterogeneous progression of emphysema in current smokers.
Emphysema distribution and annual changes in pulmonary function in male patients with chronic obstructive pulmonary disease
Naoya Tanabe, Shigeo Muro, Shiro Tanaka, Susumu Sato, Tsuyoshi Oguma, Hirofumi Kiyokawa, Tamaki Takahashi, Daisuke Kinose, Yuma Hoshino, Takeshi Kubo, Emiko Ogawa, Toyohiro Hirai, Michiaki Mishima
Respiratory Research , 2012, DOI: 10.1186/1465-9921-13-31
Abstract: We followed up 131 male patients with COPD for a median of 3.7?years. We measured wall area percent (WA%) in right apical segmental bronchus, total lung volume, percent low attenuation volume (LAV%), and the standard deviation (SD) of LAV% values from CT images of 10 isovolumetric partitions (SD-LAV) as an index of cranial-caudal emphysema heterogeneity. Annual changes in FEV1 were then determined using a random coefficient model and relative contribution of baseline clinical parameters, pulmonary function, and CT indexes including LAV%, SD-LAV, and WA% to annual changes in FEV1 were examined.The mean (SD) annual change in FEV1 was ?44.4 (10.8) mL. Multivariate random coefficient model showed that higher baseline FEV1, higher LAV%, current smoking, and lower SD-LAV independently contributed to an excessive decline in FEV1, whereas ratio of residual volume to total lung capacity, ratio of diffusing capacity to alveolar ventilation, and WA% did not, after adjusting for age, height, weight, and ratio of CT-measured total lung volume to physiologically-measured total lung capacity.A more homogeneous distribution of emphysema contributed to an accelerated decline in FEV1 independently of baseline pulmonary function, whole-lung emphysema severity, and smoking status. In addition to whole-lung analysis of emphysema, CT assessment of the cranial-caudal distribution of emphysema might be useful for predicting rapid, progressive disease and for developing a targeted strategy with which to prevent disease progression.
Thioredoxin-1 Protects against Neutrophilic Inflammation and Emphysema Progression in a Mouse Model of Chronic Obstructive Pulmonary Disease Exacerbation
Naoya Tanabe, Yuma Hoshino, Satoshi Marumo, Hirofumi Kiyokawa, Susumu Sato, Daisuke Kinose, Kazuko Uno, Shigeo Muro, Toyohiro Hirai, Junji Yodoi, Michiaki Mishima
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079016
Abstract: Background Exacerbations of chronic obstructive pulmonary disease (COPD) are characterized by acute enhancement of airway neutrophilic inflammation under oxidative stress and can be involved in emphysema progression. However, pharmacotherapy against the neutrophilic inflammation and emphysema progression associated with exacerbation has not been established. Thioredoxin-1 has anti-oxidative and anti-inflammatory properties and it can ameliorate neutrophilic inflammation through anti-chemotactic effects and prevent cigarette smoke (CS)-induced emphysema. We aimed to determine whether thioredoxin-1 can suppress neutrophilic inflammation and emphysema progression in a mouse model of COPD exacerbation and if so, to reveal the underlying mechanisms. Results Mice were exposed to CS and then challenged with polyinosine-polycytidylic acid [poly(I:C)], an agonist for virus-induced innate immunity. Airway neutrophilic inflammation, oxidative stress and lung apoptosis were enhanced in smoke-sensitive C57Bl/6, but not in smoke-resistant NZW mice. Exposure to CS and poly(I:C) challenge accelerated emphysema progression in C57Bl/6 mice. Thioredoxin-1 suppressed neutrophilic inflammation and emphysema progression. Poly(I:C) caused early neutrophilic inflammation through keratinocyte-derived chemokine and granulocyte-macrophage colony-stimulating factor (GM-CSF) release in the lung exposed to CS. Late neutrophilic inflammation was caused by persistent GM-CSF release, which thioredoxin-1 ameliorated. Thioredoxin-1 enhanced pulmonary mRNA expression of MAP kinase phosphatase 1 (MKP-1), and the suppressive effects of thioredoxin-1 on prolonged GM-CSF release and late neutrophilic inflammation disappeared by inhibiting MKP-1. Conclusion Using a mouse model of COPD exacerbation, we demonstrated that thioredoxin-1 ameliorated neutrophilic inflammation by suppressing GM-CSF release, which prevented emphysema progression. Our findings deepen understanding of the mechanisms underlying the regulation of neutrophilic inflammation by thioredoxin-1 and indicate that thioredoxin-1 could have potential as a drug to counteract COPD exacerbation.
Chromosomal differentiation of schistosomes: what is the message?
Hirohisa Hirai
Frontiers in Genetics , 2014, DOI: 10.3389/fgene.2014.00301
Abstract: As the only group of flukes with dioecism, schistosomes are unique organisms; they not only have intriguing biological and evolutionary aspects but also are responsible for major public health problems in the developing world. Schistosomiasis caused by this fluke affects approximately 210 million people in 76 countries. In order to facilitate the discovery of eradication methods for this disease, fundamental biological outcomes must be made available. Whole genome sequence data represent one such resource applicable to discovering eradication methods and measures. Herein, I describe three remarkable chromosomal changes and briefly discuss the differentiation of the Asian and African groups of this parasite taxon. Chromosomal data and evolutionary aspects will enable us to exploit genomic information for advancing schistosome studies.
Entropy Oriented Trading: A Trading Strategy Based on the Second Law of Thermodynamics
Yoichi Hirai
Physics , 2007,
Abstract: The author proposes a finance trading strategy named Entropy Oriented Trading and apply thermodynamics on the strategy. The state variables are chosen so that the strategy satisfies the second law of thermodynamics. Using the law, the author proves that the rate of investment (ROI) of the strategy is equal to or more than the rate of price change.
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