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Search Results: 1 - 10 of 4212 matches for " Yusuke Nakamura "
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On minimal log discrepancies on varieties with fixed Gorenstein index
Yusuke Nakamura
Mathematics , 2015,
Abstract: We generalize the rationality theorem of the accumulation points of log canonical thresholds which was proved by Hacon, M\textsuperscript{c}Kernan, and Xu. Further, we apply the rationality to the ACC problem on the minimal log discrepancies. We study the set of log discrepancies on varieties with fixed Gorenstein index. As a corollary, we prove that the minimal log discrepancies of three-dimensional canonical pairs with fixed coefficients satisfy the ACC.
On semi-continuity problems for minimal log discrepancies
Yusuke Nakamura
Mathematics , 2013,
Abstract: We show the semi-continuity property of minimal log discrepancies for varieties which have a crepant resolution in the category of Deligne-Mumford stacks. Using this property, we also prove the ideal-adic semi-continuity problem for toric pairs.
Personalizing carbamazepine therapy
Taisei Mushiroda, Yusuke Nakamura
Genome Medicine , 2011, DOI: 10.1186/gm243
Abstract: Carbamazepine (CBZ) is a drug frequently used as an anticonvulsant and mood stabilizer in the treatment of epilepsy and bipolar disorder. Cutaneous adverse drug reactions (cADRs) characterized by acute inflammatory reactions in skin and mucous membranes are dose-independent, unpredictable and sometimes life-threatening. Manifestations range from a mild erythematous maculopapular rash to a progressive, fulminating, severe variant with extensive mucocutaneous epithelial necrosis, Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN) and drug-induced hypersensitivity syndrome (DIHS), which is also referred to as drug rash with eosinophilia and systemic symptoms (DRESS). Almost all available drugs have been reported to have a risk of causing a cADR, and some drugs, such as CBZ, allopurinol, abacavir and nevirapine, are known to cause a very high incidence of severe cADRs, including SJS and TEN [1].It has been proposed recently that binding of drugs and/or their metabolites to human leukocyte antigen (HLA) may trigger undesirable immune responses. When the antigen is presented on HLA class II molecules, CD4+ helper T cells are activated. If the antigen is presented on class I molecules, it is likely to activate CD8+ cytotoxic T cells. Although the detailed mechanisms have not been clarified, HLA molecules are considered to be critical in the pathogenesis of severe cADRs. Therefore, genetic association analyses between HLA alleles and cADRs have been performed by many research groups, and several HLA alleles have been identified as major susceptibility factors that predispose an individual to develop cADRs. The first report demonstrating the critical involvement of a specific HLA allele in development of severe cADRs was published in 2002 [2]. This discovery had a big impact and resulted in alterations to the labeling of drugs. The report described a study of 18 Caucasian HIV patients with abacavir-induced hypersensitivity syndrome (HSS), and it revealed that t
The ACC Conjecture for minimal log discrepancies on a fixed germ
Mircea Mustata,Yusuke Nakamura
Mathematics , 2015,
Abstract: We show that on a klt germ (X,x), for every finite set I there is a positive integer N with the following property: for every R-ideal J on X with exponents in I, there is a divisor E over X that computes the minimal log discrepancy of (X,J) at x and such that its discrepancy k_E is bounded above by N. As an application, we prove Shokurov's ACC conjecture for minimal log discrepancies on a fixed klt germ.
Antifungal activity of chemotype essential oils from rosemary against Candida albicans  [PDF]
Yusuke Matsuzaki, Toshiyuki Tsujisawa, Tatsuji Nishihara, Mari Nakamura, Yasuaki Kakinoki
Open Journal of Stomatology (OJST) , 2013, DOI: 10.4236/ojst.2013.32031

Oral candidiasis is caused by Candida albicans. The symptoms including pain in the oral cavity affect our eating function. While some antifungal agents are commonly used for the treatment of candidiasis, occasional consumption of the effective dose cannot be tolerated due to side effects. There is also a possibility of induction of antifungal resistance, thus the development of replacement agents has been awaited. We aim to explore antimicrobial activities of essential oils. We evaluated the antifungal activities against C. albicans of essential oils from seven aromatic plants from three manufacturers, and of three chemotype essential oils from rosemary (Rosmarinus officinalis). As a result, we found that the antifungal activity was increased several times by the addition of Tween 80. All the tested essential oils showed stable antifungal activity, however, the variation was observed among the manufacturers of rosemary and eucalyptus. Rosemary has three chemotypes; CINEOL, CAMPHOR and VERBENON. They derived from a same plant species, but contain different chemical components. The CINEOL, dose-dependently decreased the number of C. albicans in the time-kill assay. Hence we concluded that the components of rosemary essential oil would have an effect on its antifungal activity. A chemotype is the first to consider in measuring antifungal activities of rosemary oil.

A Possible Mechanism of Cisplatin-Induced Tumor Necrosis Factor (TNF)-α Production in Murine Macrophages  [PDF]
Seikou Kim, Kouichi Yamamoto, Yusuke Nakamura, Yuichi Otoyo, Atsushi Yamatodani
Pharmacology & Pharmacy (PP) , 2013, DOI: 10.4236/pp.2013.42021
Abstract: Cisplatin has been used for the treatment of various solid cancers or sarcomas; however, it can induce severe adverse effects. Among these adverse effects, nephrotoxicity, which has the potential to be a dose-limiting factor of this agent, develops due to the secretion of tumor necrosis factor-α (TNF-α) from macrophages; however, the precise mechanisms are still unclear. To elucidate possible mechanisms, we investigated the involvement of mitogen-activated protein kinases (MAPK) and reactive oxygen species (ROS) in cisplatin-induced TNF-α mRNA expression and protein production in the mouse macrophage-like cell line, RAW 264. Cisplatin (1 μM) significantly increased TNF-α mRNA expression and protein production. Extracellular-regulated kinase (ERK) and p38 MAPK, but not c-Jun N-terminal kinase (JNK), phosphorylation increased in response to cisplatin. Although an ERK inhibitor (PD98059) suppressed both cisplatin-induced TNF-α mRNA expression and its protein production, a p38 MAPK inhibitor (SB203580) decreased TNF-α protein production only. A JNK inhibitor (SP600125) had no effect on cisplatin-induced TNF-α mRNA expression. Furthermore, a scavenger of ROS, N,N’-dimethylthiourea, suppressed both ERK activation and TNF-α mRNA expression. These results suggest that the phosphorylation of ERK by ROS is involved in cisplatin-induced TNF-α mRNA expression and that the signaling pathway of p38 MAPK is related to TNF-α protein production.
Lamiaceae Peppermint Oil with Surfactant Showing Equal Antifungal Activity against Candida albicans to Rosemary Chemotype CINEOL  [PDF]
Yusuke Matsuzaki, Yasuaki Kakinoki, Mari Nakamura, Tatsuji Nishihara, Toshiyuki Tsujisawa
Advances in Infectious Diseases (AID) , 2014, DOI: 10.4236/aid.2014.41010

Oral candidiasis causes pain in oral cavity or tongue. Antifungal drugs are commonly used for the treatment of candidiasis, however, there could be several problems such as side effects, drug resistance, or contraindication to concomitant use with drugs already taken. The development of substituting antimicrobial agents, which could be used internally or as gargling agents, is expected. Some essential oils have been known for the activities against microbes. We focused on the three chemotype essential oils from rosemary and five essential oils from Lamiaceae plants including rosemary, and examined their antifungal activity against Candida albicans by broth microdilution method. The activity with or without addition of Tween 80 or Tween 20 was statistically analyzed. Minimal inhibitory concentration (MIC) values of the essential oils were significantly decreased when either of the two surfactants was added. Among the tested oils, only CAMPHOR, a rosemary chemotype, showed a significantly lower MIC with addition of Tween 20 than Tween 80. It is inferred that the antifungal activity of essential oils is influenced by the type of surfactants. Some of the essential oils showed the same values of MIC and the minimal fungicidal concentration (MFC) when surfactant was added. Peppermint showed the same MICs and MFCs in most cases, and its low MFC indicated potent fungicidal activity against C. albicans, as observed in CINEOL. We will discuss peppermint oil as one of the potential candidates for antifungal agents against C. albicans.

The Textile Plot: A New Linkage Disequilibrium Display of Multiple-Single Nucleotide Polymorphism Genotype Data
Natsuhiko Kumasaka,Yusuke Nakamura,Naoyuki Kamatani
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0010207
Abstract: Linkage disequilibrium (LD) is a major concern in many genetic studies because of the markedly increased density of SNP (Single Nucleotide Polymorphism) genotype markers. This dramatic increase in the number of SNPs may cause problems in statistical analyses, such as by introducing multiple comparisons in hypothesis testing and colinearity in logistic regression models, because of the presence of complex LD structures. Inferences must be made about the underlying genetic variation through the LD structure before applying statistical models to the data. Therefore, we introduced the textile plot to provide a visualization of LD to improve the analysis of the genetic variation present in multiple-SNP genotype data. The plot can accentuate LD by displaying specific geometrical shapes, and allowing for the underlying haplotype structure to be inferred without any haplotype-phasing algorithms. Application of this technique to simulated and real data sets illustrated the potential usefulness of the textile plot as an aid to the interpretation of LD in multiple-SNP genotype data. The initial results of LD mapping and haplotype analyses of disease genes are encouraging, indicating that the textile plot may be useful in disease association studies.
Analysis of Particle Transfer by Periodic Lattice Modulation for Ultracold Fermionic Atom Systems in Three Dimensional Optical Lattice
Motoyoshi Inoue,Yusuke Nakamura,Yoshiya yamanaka
Physics , 2013, DOI: 10.7566/JPSJ.83.024604
Abstract: We analyze a ultracold fermionic atom system in a three dimensional optical lattice with a confinement harmonic potential, using the Hubbard model, and time-dependent Gutzwiller variational approach for numerical calculation. Our study is focused on the time evolution of the particle transfer when the lattice potential is modulated by adding a periodic one. The choice of the parameters such as the modulation frequency and amplitude and the particle number affects the particle transfer. We calculate the time evolution of the variance in the particle distribution, and show its dependence on the parameters. The lattice modulation turns out to work effectively in order to control the particle transfer, and will be a useful method in experiments for fermionic atom systems.
Effect of electron-phonon interactions on orbital fluctuations in iron-based superconductors
Yusuke Nomura,Kazuma Nakamura,Ryotaro Arita
Physics , 2013, DOI: 10.1103/PhysRevLett.112.027002
Abstract: To investigate the possibility whether electron-phonon coupling can enhance orbital fluctuations in iron-based superconductors, we develop an ab initio method to construct the effective low-energy models including the phonon-related terms. With the derived effective electron-phonon interactions and phonon frequencies, we estimate the static part (\omega=0) of the phonon-mediated effective on-site intra- or inter-orbital electron-electron attractions as ~ -0.4 eV and exchange or pair-hopping terms as ~ -0.02 eV. We analyze the model with the derived interactions together with the electronic repulsions within the random phase approximation. We find that the enhancement of the orbital fluctuations due to the electron-phonon interactions is small, making the spin fluctuations dominant. As a result, the superconducting state with the sign reversal in gap functions ($s_\pm$-wave) is realized.
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