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Search Results: 1 - 10 of 1098 matches for " Yuichi Matsuura "
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A Rapid Bioassay for Classical and L-Type Bovine Spongiform Encephalopathies  [PDF]
Yuichi Matsuura, Yukiko Ishikawa, Robert A. Somerville, Takashi Yokoyama, Ken’ichi Hagiwara, Yoshio Yamakawa, Tetsutaro Sata, Tetsuyuki Kitamoto, Shirou Mohri
Open Journal of Veterinary Medicine (OJVM) , 2013, DOI: 10.4236/ojvm.2013.31013
Abstract:

The rapid detection of infectivity of several agents that cause Creutzfeldt-Jakob disease has previously been achieved by assaying for deposits of abnormal prion protein (PrPSc) in follicular dendritic cells in the spleens of transgenic mice carrying the human prion protein gene. In this study, transgenic mice expressing the bovine prion protein were inoculated intraperitoneally with classical (C-type) or atypical L-type bovine spongiform encephalopathies (BSE). Proteinase-resistant PrPSc were detected in the spleens of all transgenic mice at 75 days after inoculation with both types of BSE. Infectivity in PrPSc-positive spleens of the transgenic mice revealed that prions of C- and L-type BSE replicated. These results suggest that bioassay system by the transgenic mice could be useful for the rapid detection of BSE infectivity with discriminating between C- and L-type BSEs.

Intraspecies Prion Transmission Results in Selection of Sheep Scrapie Strains
Takashi Yokoyama,Kentaro Masujin,Mary Jo Schmerr,Yujing Shu,Hiroyuki Okada,Yoshifumi Iwamaru,Morikazu Imamura,Yuichi Matsuura,Yuichi Murayama,Shirou Mohri
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015450
Abstract: Sheep scrapie is caused by multiple prion strains, which have been classified on the basis of their biological characteristics in inbred mice. The heterogeneity of natural scrapie prions in individual sheep and in sheep flocks has not been clearly defined.
Sulfated Dextrans Enhance In Vitro Amplification of Bovine Spongiform Encephalopathy PrPSc and Enable Ultrasensitive Detection of Bovine PrPSc
Yuichi Murayama,Miyako Yoshioka,Kentaro Masujin,Hiroyuki Okada,Yoshifumi Iwamaru,Morikazu Imamura,Yuichi Matsuura,Shigeo Fukuda,Sadao Onoe,Takashi Yokoyama,Shirou Mohri
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013152
Abstract: Prions, infectious agents associated with prion diseases such as Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE) in cattle, and scrapie in sheep and goats, are primarily comprised of PrPSc, a protease-resistant misfolded isoform of the cellular prion protein PrPC. Protein misfolding cyclic amplification (PMCA) is a highly sensitive technique used to detect minute amounts of scrapie PrPSc. However, the current PMCA technique has been unsuccessful in achieving good amplification in cattle. The detailed distribution of PrPSc in BSE-affected cattle therefore remains unknown.
Recent Advances in X-Ray Structures of Metal-Phenoxyl Radical Complexes  [PDF]
Yuichi Shimazaki
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.31A009
Abstract:

An “experimental” valence state of metal complexes is sometime different from the “formal” oxidation state, especially in the species having redox active ligands. This difference can be seen in biological system, such as iron(IV)-porphyrin π-cation radical in some heme proteins and copper(II)-phenoxyl radical in galactose oxidase (GO). Although structural characterizations of these species by X-ray diffraction methods have been rare due to their stability, some artificial metal-phenoxyl radical complexes have been synthesized and successfully characterized by X-ray crystal structure. In this review, syntheses and X-ray crystal structures of the one-electron oxidized metal-phenolate complexes, metal- phenoxyl radical, and high-valent metal phenolate species are discussed.

Relationships among Risk Assessment, Risk Perception and Acceptance Model of the Residents near Nuclear Power Plants in Japan  [PDF]
Yuichi Otsuka
Open Journal of Safety Science and Technology (OJSST) , 2015, DOI: 10.4236/ojsst.2015.52005
Abstract: This study aims at revealing the relationships among risk assessment result, risk perception model and risk acceptance model of the residents near nuclear power plants in Japan. Risk acceptance model is based on the trust of resident to nuclear power plants (NPPs) companies. The risk perception of the residents is very fragile and is not always based on objective technical knowledge. In addition, there are two models of risk acceptance: traditional trust model and salient value similarity model. In order to discuss the risk communication framework between NPPs with residents, applicability of two modes on the perception of the residents should be investigated. The author collected questionnaire from local resident near Kashiwazaki-Kariwa NPP in Niigata, Japan. Severity of risk is significantly affected by the extents of risks, not by amount of knowledge. Radiation relating hazard is normally evaluated higher risk. Risk acceptance level is significantly related to the factors of social benefits and trust to the NPPs company, not by regional interest nor amount of knowledge. Furthermore, value similarity model was not significant in this study. The results demonstrated that risk acceptance model of local residents near NPPs could be arranged by traditional trust model. In order to establish mutual trustworthy relationships between local residents and NPPs engineer, expert knowledge in nuclear power, communication skills, and expertise in safety are necessary to the engineers.
Experimental H-type bovine spongiform encephalopathy characterized by plaques and glial- and stellate-type prion protein deposits
Hiroyuki Okada, Yoshifumi Iwamaru, Morikazu Imamura, Kentaro Masujin, Yuichi Matsuura, Yoshihisa Shimizu, Kazuo Kasai, Shirou Mohri, Takashi Yokoyama, Stefanie Czub
Veterinary Research , 2011, DOI: 10.1186/1297-9716-42-79
Abstract: Bovine spongiform encephalopathy (BSE), which belongs to a group of diseases called transmissible spongiform encephalopathies (TSE), is a fatal neurodegenerative disorder of cattle. BSE was first identified in the United Kingdom in 1986 [1], then spread to European as well as North American countries and Japan, and has affected more than 190 000 cattle in the world. The infectious agent responsible for TSE is the disease-associated prion protein (PrPSc), which is thought to be a post-translationally modified form of the host-encoded membrane glycoprotein (PrPC) [2]. According to the protein-only hypothesis, PrPSc is the principal component of the infectious agent.On the basis of uniform pathology and biochemical profile of the protease-resistant prion protein (PrPres) among BSE-affected cattle, it is assumed that BSE in cattle is caused by only one prion strain. Since 2003, variants of BSE (named atypical BSE) have been detected in Japan, Europe, and North America and classified in at least two groups, namely, H-type and L-type BSE, according to the molecular mass of PrPres, compared with those of the classical BSE (named C-type BSE) [3]. H-type BSE was first identified in France [4], and L-type BSE, called bovine amyloidotic spongiform encephalopathy (BASE), was first detected in Italy [5]. It is accepted that C-type BSE is caused by the consumption of BSE-contaminated feed, whereas the origins of H-type and L-type BSE remain enigmatic. Hypotheses for the origin of atypical BSE include (1) infection of cattle with different BSE agents; (2) infection of cattle with a non-bovine source or unrecognized forms of infectious TSE agents; (3) genetic mutations in the prion protein gene; and (4) spontaneous or so-called sporadic forms of TSE in cattle, limited to old age, like the sporadic form of human Creutzfeldt-Jakob disease (CJD) [6-10]. However, only one genetic mutation has been found in an H-type BSE case [11]. Sequence analysis of the open reading frame (ORF) of th
The N-Terminal Sequence of Prion Protein Consists an Epitope Specific to the Abnormal Isoform of Prion Protein (PrPSc)
Kentaro Masujin, Yuko Kaku-Ushiki, Ritsuko Miwa, Hiroyuki Okada, Yoshihisa Shimizu, Kazuo Kasai, Yuichi Matsuura, Takashi Yokoyama
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058013
Abstract: The conformation of abnormal prion protein (PrPSc) differs from that of cellular prion protein (PrPC), but the precise characteristics of PrPSc remain to be elucidated. To clarify the properties of native PrPSc, we attempted to generate novel PrPSc-specific monoclonal antibodies (mAbs) by immunizing PrP-deficient mice with intact PrPSc purified from bovine spongiform encephalopathy (BSE)-affected mice. The generated mAbs 6A12 and 8D5 selectivity precipitated PrPSc from the brains of prion-affected mice, sheep, and cattle, but did not precipitate PrPC from the brains of healthy animals. In histopathological analysis, mAbs 6A12 and 8D5 strongly reacted with prion-affected mouse brains but not with unaffected mouse brains without antigen retrieval. Epitope analysis revealed that mAbs 8D5 and 6A12 recognized the PrP subregions between amino acids 31–39 and 41–47, respectively. This indicates that a PrPSc-specific epitope exists in the N-terminal region of PrPSc, and mAbs 6A12 and 8D5 are powerful tools with which to detect native and intact PrPSc. We found that the ratio of proteinase K (PK)-sensitive PrPSc to PK-resistant PrPSc was constant throughout the disease time course.
Novel Synthetic Method for the Vilsmeier-Haack Reagent and Green Routes to Acid Chlorides, Alkyl Formates, and Alkyl Chlorides  [PDF]
Yoshikazu Kimura, Daisuke Matsuura
International Journal of Organic Chemistry (IJOC) , 2013, DOI: 10.4236/ijoc.2013.33A001
Abstract: An environmentally benign and practical preparation method for the Vilsmeier-Haack reagent (VH) has been developed by using phthaloyl dichloride with DMF in toluene or 2-chlorotoluene. Phthalic anhydride as the byproduct was recovered in high yield by simple filtration. Some aromatic acids have been transformed into the corresponding acid chlorides in good yields by employing the isolated VH. Treatment of primary or secondary alcohols with VH gave alkyl formates or alkyl chlorides by depending on the reaction conditions.
Empirical Investigation of Threats to Loyalty Programs by Using Models Inspired by the Gordon-Loeb Formulation of Security Investment  [PDF]
Shiori Shinoda, Kanta Matsuura
Journal of Information Security (JIS) , 2016, DOI: 10.4236/jis.2016.72003
Abstract: Loyalty program (LP) is a popular marketing activity of enterprises. As a result of firms’ effort to increase customers’ loyalty, point exchange or redemption services are now available worldwide. These services attract not only customers but also attackers. In pioneering research, which first focused on this LP security problem, an empirical analysis based on Japanese data is shown to see the effects of LP-point liquidity on damages caused by security incidents. We revisit the empirical models in which the choice of variables is inspired by the Gordon-Loeb formulation of security investment: damage, investment, vulnerability, and threat. The liquidity of LP points corresponds to the threat in the formulation and plays an important role in the empirical study because it particularly captures the feature of LP networks. However, the actual proxy used in the former study is artificial. In this paper, we reconsider the liquidity definition based on a further observation of LP security incidents. By using newly defined proxies corresponding to the threat as well as other refined proxies, we test hypotheses to derive more implications that help LP operators to manage partnerships; the implications are consistent with recent changes in the LP network. Thus we can see the impacts of security investment models include a wider range of empirical studies.
Matrices and Division by Zero z/0 = 0  [PDF]
Tsutomu Matsuura, Saburou Saitoh
Advances in Linear Algebra & Matrix Theory (ALAMT) , 2016, DOI: 10.4236/alamt.2016.62007
Abstract: In this paper, a new viewpoint of the division by zero z/0 = 0 in matrices is introduced and the results will show that the division by zero is our elementary and fundamental mathematics. New and practical meanings for many mathematical and physical formulas for the denominator zero cases may be given. Furthermore, a new space idea for the point at infinity for the Eucleadian plane is also introduced.
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