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Search Results: 1 - 10 of 2545 matches for " Akira Sawaki "
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Impact of Rechallenge with Imatinib in Patients with Advanced Gastrointestinal Stromal Tumor after Failure of Imatinib and Sunitinib
Akira Sawaki,Tatsuo Kanda,Yoshito Komatsu,Toshirou Nishida
Gastroenterology Research and Practice , 2014, DOI: 10.1155/2014/342986
Abstract: Purpose. This retrospective, nonrandomized study investigated the effect of imatinib rechallenge plus best supportive care (BSC) on overall survival after imatinib and sunitinib treatment for patients with locally advanced or metastatic gastrointestinal stromal tumor (GIST). Methods. Twenty-six patients who had previously been exposed to both imatinib and sunitinib were enrolled in this study. The treatment regimen was BSC with or without imatinib, based on the patient’s choice after discussion with his or her physician. The primary endpoint was overall survival, and secondary endpoints were time to treatment failure, clinical response rate assessed by Choi criteria, and safety. Results. Fourteen patients were treated with imatinib plus BSC and 12 received BSC alone. Median overall survival was greatly improved for the imatinib group, although differences were not significant (22 months for imatinib plus BSC versus 4 months for BSC; ). Three patients (21%) had a clinical response in the imatinib group, and one had a clinical response in the BSC alone group. Imatinib was well tolerated. Conclusions. Rechallenge with imatinib may be associated with improvement in overall survival without deteriorating performance status in patients who failed imatinib and sunitinib. A prospective study should be considered to confirm the efficacy of rechallenge with imatinib. 1. Introduction Gastrointestinal stromal tumor (GIST) is the most common type of nonepithelial tumor occurring in the gastrointestinal (GI) tract, including the peritoneum [1]. GISTs cannot always be distinguished from myogenic or neurogenic neoplasms by routine histological methods; as such, immunohistochemistry is often needed to distinguish GISTs from other spindle cell tumors. GISTs are generally considered to be KIT (CD117) positive tumors [2]. The tumor probably arises from KIT or platelet-derived growth factor receptor A (PDGFRA) gene mutations in precursor cells that normally give rise to the interstitial cells of Cajal [3–5]. Some GISTs are clinically malignant and metastasize predominantly to the liver and peritoneum [1, 6, 7]. About 85–90% of GISTs are associated with gain-of-function KIT gene mutations that lead to constitutive activation of KIT kinase activity [3]. A much smaller proportion of GISTs are associated with analogous gain-of-function mutations in PDGFRA, the gene-encoding platelet-derived growth factor receptor (PDGFR ); less than 10% contain no identified receptor tyrosine kinase mutations [8, 9]. Activating mutations of KIT or PDGFRA have been identified in the development
Game Russian Options for Double Exponential Jump Diffusion Processes  [PDF]
Atsuo Suzuki, Katsushige Sawaki
Journal of Mathematical Finance (JMF) , 2014, DOI: 10.4236/jmf.2014.41005

In this paper, we deal with the valuation of Game Russian option with jumps, which is a contract that the seller and the buyer have both the rights to cancel and to exercise it at any time, respectively. This model can be formulated as a coupled optimal stopping problem. First, we discuss the pricing model with jumps when the stock pays dividends continuously. Secondly, we derive the value function of Game Russian options and investigate properties of optimal boundaries of the buyer. Finally, some numerical results are presented to demonstrate analytical properties of the value function.

Gemcitabine sensitivity-related mRNA expression in endoscopic ultrasound-guided fine-needle aspiration biopsy of unresectable pancreatic cancer
Reiko Ashida, Bunzo Nakata, Minoru Shigekawa, Nobumasa Mizuno, Akira Sawaki, Kosei Hirakawa, Tetsuo Arakawa, Kenji Yamao
Journal of Experimental & Clinical Cancer Research , 2009, DOI: 10.1186/1756-9966-28-83
Abstract: mRNAs extracted from 35 pancreatic tubular adenocarcinoma tissues obtained by EUS-FNA before GEM-treatment were studied. mRNAs were amplified and applied to a Focused DNA Array, which was restricted to well-known genes, including GEM sensitivity-related genes, deoxycytidine kinase (dCK), human equilibrative nucleoside transporter 1 (hENT1), hENT2, dCMP deaminase, cytidine deaminase, 5'-nucleotidase, ribonucleotide reductase 1 (RRM1) and RRM2. mRNA levels were classified into high and low expression based on a cut-off value defined as the average expression of 35 samples. These 35 patients were divided into the following two groups. Patients with partial response and those with stable disease whose tumor markers decreased by 50% or more were classified as the effective group. The rest of patients were classified as the non-effective group. The relationship between GEM efficacy and mRNA expression was then examined by chi-squared test.Among these GEM sensitivity-related genes, dCK alone showed a significant correlation with GEM efficacy. Eight of 12 patients in the effective group had high dCK expression, whereas 16 of 23 patients in non-effective group had low dCK expressions (P = 0.0398).dCK mRNA expression is a candidate indicator for GEM efficacy in unresectable pancreatic cancer. Quantitative mRNA measurements of dCK using EUS-FNA samples are necessary for definitive conclusions.Pancreatic cancer is one of the most lethal human cancers. The standard treatment for unresectable pancreatic cancer was previously 5-fluorouracil (5-FU)-based chemotherapy. In 1997, however, it was reported that gemcitabine (GEM) conferred significantly longer survival and clinical benefits when compared to 5-FU in patients with locally advanced or metastatic pancreatic cancer [1]. Since that time, GEM has been recognized as the standard treatment for this disease.Recent investigations using cell lines or surgical specimens have revealed that the expressions of human equilibrative nucleo
Callable Russian Options and Their Optimal Boundaries
Atsuo Suzuki,Katsushige Sawaki
Advances in Decision Sciences , 2009, DOI: 10.1155/2009/593986
Abstract: We deal with the pricing of callable Russian options. A callable Russian option is a contract in which both of the seller and the buyer have the rights to cancel and to exercise at any time, respectively. The pricing of such an option can be formulated as an optimal stopping problem between the seller and the buyer, and is analyzed as Dynkin game. We derive the value function of callable Russian options and their optimal boundaries.
Cerebral Low-Molecular Metabolites Influenced by Intestinal Microbiota: A Pilot Study
Mitsuharu Matsumoto,Emiko Sawaki,Yoshimi Benno
Frontiers in Systems Neuroscience , 2013, DOI: 10.3389/fnsys.2013.00009
Abstract: Recent studies suggest that intestinal microbiota influences gut-brain communication. In this study, we aimed to clarify the influence of intestinal microbiota on cerebral metabolism. We analyzed the cerebral metabolome of germ-free (GF) mice and Ex-GF mice, which were inoculated with suspension of feces obtained from specific pathogen-free mice, using capillary electrophoresis with time-of-flight mass spectrometry (CE-TOFMS). CE-TOFMS identified 196 metabolites from the cerebral metabolome in both GF and Ex-GF mice. The concentrations of 38 metabolites differed significantly (p < 0.05) between GF and Ex-GF mice. Approximately 10 of these metabolites are known to be involved in brain function, whilst the functions of the remainder are unclear. Furthermore, we observed a novel association between cerebral glycolytic metabolism and intestinal microbiota. Our work shows that cerebral metabolites are influenced by normal intestinal microbiota through the microbiota-gut-brain axis, and indicates that normal intestinal microbiota closely connected with brain health and disease, development, attenuation, learning, memory, and behavior.
Phosphorus Release from Sediments in a Riparian Phragmites australis Community at the Estuary of the Chikugogawa River, Western Japan  [PDF]
Akira Haraguchi
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.37114
Abstract: In order to determine the contribution of aquatic macrophyte communities on nutrition to sustain the high primary productivity of an estuary aquatic community, we analyzed the process of phosphorus release from sediments in aquatic macrophyte community in the estuary of the Chikugogawa River, South-Western Japan. Vertical profile of PD3-4 concentration and redox potential (Eh) of pore water in sediments were investigated within and outside the Phragmites australis community. Sediment horizon lower than 23 cm layer from the surface showed anaerobic (Eh < -200 mV) in the P. australis community, whereas sediment was constantly oxic (Eh > 0 mV) up to 50 cm depth outside the P. australis community without organic matter accumulation. Non-vegetated sediment with organic matter accumulation showed anoxic profile as vegetated site. PD3-4 concentration in anaerobic parts of sediment showed higher than oxic parts, and higher PD3-4 concentration in sediment pore water corresponded to sulfur deposition in sediment. Sulfate ion supplied from the sea water is reduced under the anoxic condition and S2- reacts with water-insoluble phosphorus salts e.g. Fe3(PO4)2 or AlPO4 and Fe2S3 or Al2S3 precipitates. Thus PD3-4 was mobilized and released under anoxic sediments. P. australis supply organic litter to sediment and the sediment within the P. australis community showed anoxic after aerobic decomposition of organic substances in sediment. Incubation of sediments under N2 atmosphere accumulated PD3-4 in the medium corresponding to low Eh (< -300 mV) showing that PD3-4 was released under anaerobic condition. Estuary P. australis community has function for supplying PD3-4 to river water.
Analysis of the Tracer Diffusion Phenomena through Cracks in the Porous Media by Means of X-Ray CT  [PDF]
Akira Sato
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.48A003

The migration process of contamination materials in the porous rock mass was visualized and analyzed by X-ray CT image data. In this study, Kimachi sandstone, which had approximately 26% porosity, was used as a rock sample. Here two cases of diffusion phenomena were analyzed. One is the case that solute diffuses into the porous rock mass from the crack surfaces, and it simulates the contamination process of rock mass. Another is the case that the solute diffuses out of the porous rock mass, and it simulates the process that the contamination materials spread from highly contaminated sources. It was found that the diffusion phenomena were clearly visualized by X-ray CT method. By introducing the parameter, coefficient of tracer density increment α, quantitative analysis of tracer density became possible, and the relation between the density distribution of tracer and the crack apertures and the relation between the density distribution and porosity distribution became clear.

Effects of Salinity on Germination, Seedling Growth and Ecological Properties of Phragmites australis Communities in the Estuary of the Chikugogawa River, Southwestern Japan  [PDF]
Akira Haraguchi
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.55073

Salt tolerance of Phragmites australis populations was investigated in natural reed habitats in the estuary of the Chikugogawa River, southwestern Japan. P. australis populations were selected along the salinity gradient in the estuary, including limnetic (salinity 0.05%), oligohaline (0.4%) and polyhaline sections (2.5%). The ratio of Total-P/Total-N of river water showed high values in the oligohaline section and the above ground biomass, population height and culm diameter of P. australis showed maximum values in this section. Sufficient phosphorus supply could sustain the high productivity of the community in the oligohaline section, irrespective of the salinity of inundated water. The seed production of P. australis was lowest in the polyhaline section. Thus, the ecological performance of P. australis was highest in the oligohaline section and the performance declined with the increasing salinity of the habitat. The effects of salinity on germination and seedling growth were evaluated by means of cultivation in 0.0% -5.0% (NaCl w/w%) salinity medium. Seeds of P. australis collected from every natural population in the estuary failed to germinate at salinity levels above 2.3%. Growth of shoot length and above-ground biomass of seedlings germinated in the fresh water medium were measured for 21 days’ exposure to constant salinity solutions ranging from 0.0% -5.0%. Although mortality was high at salinity levels 3.5% and 5.0%, elongation of shoots of some plants was evident at a salinity level of 5.0%. Seeds from the population in the limnetic section

Extendibility Evaluation of Industrial EUV Source Technologies for kW Average Power and 6.x nm Wavelength Operation  [PDF]
Akira Endo
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.55039

Interests in the extendibility are growing after the introduction of the LPP (Laser Produced Plasma) EUV source technology in the semiconductor industry, towards higher average power and shorter wavelength, based on the basic architecture of the established LPP EUV source technology. It is discussed in this article that the power scaling of the 13.5nm wavelength source is essentially possible by a slight increase of the driving laser power, CE (Conversion Efficiency) and EUV collection efficiency by some introduction of novel component technologies. Extension of the EUV wavelength towards BEUV (Beyond EUV), namely 6.x nm is discussed based on the general rule of the UTA (Unresolved Transition Arrays) of high Z ions, and development of multilayer mirrors in this particular wavelength region. Technical difficulties are evaluated for the extension of the LPP source technology by considering the narrower mirror bandwidth and higher melting temperature of the candidate plasma materials. Alternative approach based on the superconducting FEL is evaluated in comparison with the LPP source technology for the future solution.

Effect of Degree of Cure on Sandwich Structural Capacitor Using Ion-Conductive Polymer with Carbon Fabric Skins  [PDF]
Akira Todoroki
Open Journal of Composite Materials (OJCM) , 2016, DOI: 10.4236/ojcm.2016.64011
Abstract: Structural capacitors are composite structures that function as energy storage capacitors. An electric double-layer capacitor with a composite structure using a solid polymer electrolyte matrix with a glass fiber fabric separator has recently been developed. In the present study, new foam core sandwich structure is adopted and the effect of the degree of cure is experimentally investigated. Carbon fiber fabric cloth is used as electrodes, and the polystyrene foam core is used as separator. Material system of Poly Ethylene Glycol DiGlycidyl Ether (PEGDGE) with Lithium bisTriFluoromethane Sulfonyl Imide (LiTFSI) and hardener of TriEthylene TetrAmine (TETA) is adopted as ion-conductive polymer matrix. The effect of the cure degree is experimentally investigated by using 100% cure degree, 70% cure degree and 0% cure degree specimens. As a result, the polystyrene foam-core sandwich system is proved to be effective, but the capacitance is not enough because of the lack of surface area of the carbon fiber electrodes. As the remained TETA impedes the movement of Li+ cation in the solid polymer by means of the segment-motion-assisted diffusion process, the low degree of cure causes small capacitance with this material system.
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