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Search Results: 1 - 10 of 2218 matches for " Makoto Obara "
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Synthesis of sialoglycopolypeptide for potentially blocking influenza virus infection using a rat α2,6-sialyltransferase expressed in BmNPV bacmid-injected silkworm larvae
Makoto Ogata, Makoto Nakajima, Tatsuya Kato, Takakiyo Obara, Hirokazu Yagi, Koichi Kato, Taichi Usui, Enoch Y Park
BMC Biotechnology , 2009, DOI: 10.1186/1472-6750-9-54
Abstract: FLAG-tagged recombinant ST6Gal1 was expressed efficiently and purified by precipitation with ammonium sulphate followed by affinity chromatography on an anti-FLAG M2 column, generating 2.2 mg purified fusion protein from only 11 silkworm larvae, with a recovery yield of 64%. The purified ST6Gal1 was characterized and its N-glycan patterns were found to be approximately paucimannosidic type by HPLC mapping method. Fluorescently-labelled N-acetyllactosamine (LacNAc) glycoside containing dansyl group was synthesized chemo-enzymatically as high-sensitivity acceptor substrate for ST6Gal1. The acceptor substrate specificity of the enzyme was similar to that of rat liver ST6Gal1. The fluorescent glycoside is useful as a substrate for a highly sensitive picomole assay of ST6Gal1. Asialoglycopolypeptide was regioselectively and quantitatively sialylated by catalytic reaction at the terminal Gal residue to obtain α2,6-sialoglycopolypeptide using ST6Gal1. The α2,6-sialoglycopolypeptide selectively inhibited hemagglutination induced by Sambucus nigra (SNA) lectin, showing about 780-fold higher affinity than the control fetuin. Asialoglycopolypeptide and γ-polyglutamic acid did not affect SNA lectin-mediated hemagglutination.The recombinant ST6Gal1 from a silkworm expression system is useful for the sialylation of asialoglycopeptide. The sialylated glycoprotein is a valuable tool for investigating the molecular mechanisms of biological and physiological events, such as cell-cell recognition and viral entry during infection.Sialic acids are distributed in a variety of glycolipids and glycoproteins, often existing at the non-reducing termini of carbohydrate chains. Sialic acids play important roles in various biological and physiological events [1,2]. Sialic acid is added to the terminal sugar of glycoproteins and glycolipids by sialyltransferase (SiaT) enzymes. The sialic acid that is added to a galactose (Gal) can be bound either to the hydroxyl attached to carbon-3 of Gal to fo
The Welfare Comparison of Ad-Valorem Tax and Specific Tax with Both Quality and Quantity Choice of a Consumer  [PDF]
Takuya Obara, Shuichi Tsugawa
Theoretical Economics Letters (TEL) , 2017, DOI: 10.4236/tel.2017.76122
Abstract: This paper compares ad-valorem and specific taxation in models where a representative consumer with an exogenous income has both a quality and a quantity choice under perfect competition. In the setting, while ad-valorem tax causes income effect only, specific tax causes both income effect and substitution effect. Therefore, ad-valorem tax decreases consumer demand for both quality and quantity; on the other hand, specific tax decreases consumer demand for quantity. However, the sign of consumer demand for quality is ambiguous and is determined by the curvature of marginal utility on quantity. Additionally, using a constant elasticity of substitution (CES) utility function and a linear price function, we show that ad-valorem tax is superior to specific tax except for the Leontief preference under which the two forms of commodity taxes generate the same tax revenue. The substitution effect caused by specific tax disappears if the elasticity of substitution converges to zero.
The Principal of Dynamic Contrast Enhanced MRI, the Method of Pharmacokinetic Analysis, and Its Application in the Head and Neck Region
Toru Chikui,Makoto Obara,Arjan W. Simonetti,Masahiro Ohga,Shoichi Koga,Shintaro Kawano,Yoshio Matsuo,Takeshi Kamintani,Tomoko Shiraishi,Erina Kitamoto,Katsumasa Nakamura,Kazunori Yoshiura
International Journal of Dentistry , 2012, DOI: 10.1155/2012/480659
Abstract: Many researchers have established the utility of the dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) in the differential diagnosis in the head and neck region, especially in the salivary gland tumors. The subjective assessment of the pattern of the time-intensity curve (TIC) or the simple quantification of the TIC, such as the time to peak enhancement ( ) and the wash-out ratio (WR), is commonly used. Although the semiquantitative evaluations described above have been widely applied, they do not provide information on the underlying pharmacokinetic analysis in tissue. The quantification of DCE-MRI is preferable; therefore, many compartment model analyses have been proposed. The Toft and Kermode (TK) model is one of the most popular compartment models, which provide information about the influx forward volume transfer constant from plasma into the extravascular-extracellular space (EES) and the fractional volume of EES per unit volume of tissue is used in many clinical studies. This paper will introduce the method of pharmacokinetic analysis and also describe the clinical application of this technique in the head and neck region. 1. Introduction The technique of dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI), in which multiphase MRI scans are taken following the intravenous injection of a contrast agent, has been widely used in clinical practice. Many researchers have established the utility of the DCE-MRI in the differential diagnosis of salivary gland tumors [1–3]. DCE-MRI can successfully demonstrate the nature of a lymphoma and is helpful for making a differential diagnosis from other lesions [4]. Some researcher have also attempted to utilize DCE-MRI for lesions in the jaw bone [5–7]. The most conventional assessment using DCE-MRI may, therefore, be to use the characteristics of the time-intensity curve (TIC) regarding the regions of interest (ROIs), which are delineated by the observers. The subjective assessment of the pattern of the TIC or the simple quantification of the TIC, such as the time to peak enhancement ( ) and the wash-out ratio (WR), is also commonly used.  Although the semiquantitative evaluations described above have been widely applied, they do not provide information on the underlying pharmacokinetic nature in the tissue. Moreover, an analysis based on the signal intensity (SI) is predominantly affected by the scan parameters. Therefore, it is difficult to compare the results obtained at different institutes. Conversely, a pharmacokinetic analysis enables the quantification of contrast agent
On Canard Homoclinic of a Liénard Perturbation System  [PDF]
Makoto Hayashi
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.210170
Abstract: The classification on the orbits of some Liénard perturbation system with several parameters, which is relation to the example in [1] or [2], is discussed. The conditions for the parameters in order that the system has a unique limit cycle, homoclinic orbits, canards or the unique equilibrium point is globally asymptotic stable are given. The methods in our previous papers are used for the proofs.
Traffic Dynamics and Congested Phases Derived from an Extended Optimal-Velocity Model  [PDF]
Makoto Watanabe
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.68048

Dynamics is studied for one-dimensional single-lane traffic flow by means of an extended optimal-velocity model with continuously varied bottleneck strength for nonlinear roads. Two phases exist in this model such as free flow and wide moving jam states in the systems having relatively small values of the bottleneck strength parameter. In addition to the two phases, locally congested phaseappears as the strength becomes prominent. Jam formation occurs with the similar mechanism to the boomerang effect as well as the pinch one in it. Wide scattering of the flow-density relation in fundamental diagram is found in the congested phase.

Employment Protection, Employers’ Hiring Strategies and the Screening Role of Temporary Contracts  [PDF]
Makoto Masui
Modern Economy (ME) , 2016, DOI: 10.4236/me.2016.77080
Abstract: In this paper, we develop a matching model with both permanent and temporary contracts to address situations in which the quality of a match formed by a worker-firm pair is not observable to both workers and firms. The screening and cost-saving aspects of temporary employment contracts are two primary reasons that firms use them, but screening has received little attention in the study of employment protection. We show that increasing dismissal costs decreases job creation and that higher dismissal costs are likely to reduce the hiring threshold for temporary jobs and raise the threshold for permanent jobs. We also examine how changes in dismissal costs affect the average productivity of permanent jobs and discuss the effectiveness of the policy of increasing labour market flexibility by weakening firing restrictions for permanent employment.
On Utilization of K-Means for Determination of q-Parameter for Tsallis-Entropy-Maximized-FCM  [PDF]
Makoto Yasuda
Journal of Software Engineering and Applications (JSEA) , 2017, DOI: 10.4236/jsea.2017.107033
Abstract: In this paper, we consider a fuzzy c-means (FCM) clustering algorithm combined with the deterministic annealing method and the Tsallis entropy maximization. The Tsallis entropy is a q-parameter extension of the Shannon entropy. By maximizing the Tsallis entropy within the framework of FCM, membership functions similar to statistical mechanical distribution functions can be derived. One of the major considerations when using this method is how to determine appropriate q values and the highest annealing temperature, Thigh?, for a given data set. Accordingly, in this paper, a method for determining these values simultaneously without introducing any additional parameters is presented. In our approach, the membership function is approximated by a series of expansion methods and the K-means clustering algorithm is utilized as a preprocessing step to estimate a radius of each data distribution. The results of experiments indicate that the proposed method is effective and both q and Thigh can be determined automatically and algebraically from a given data set.
Atg14: A Key Player in Orchestrating Autophagy
Keisuke Obara,Yoshinori Ohsumi
International Journal of Cell Biology , 2011, DOI: 10.1155/2011/713435
Abstract: Phosphorylation of phosphatidylinositol (PtdIns) by a PtdIns 3-kinase is an essential process in autophagy. Atg14, a specific subunit of one of the PtdIns 3-kinase complexes, targets the complex to the probable site of autophagosome formation, thereby, sorting the complex to function specifically in autophagy. The N-terminal half of Atg14, containing coiled-coil domains, is required to form the PtdIns 3-kinase complex and target it to the proper site. The C-terminal half of yeast Atg14 is suggested to be involved in the formation of a normal-sized autophagosome. The C-terminal half of mammalian Atg14 contains the Barkor/Atg14(L) autophagosome-targeting sequence (BATS) domain that preferentially binds to the highly curved membranes containing PtdIns(3)P and is proposed to target the PtdIns 3-kinase complex efficiently to the isolation membrane. Thus, the N- and C-terminal halves of Atg14 are likely to have an essential core function and a regulatory role, respectively. 1. PtdIns 3-Kinase in Autophagy Eukaryotic cells can enclose their own cytoplasmic components in a double-membrane structure, the autophagosome, and deliver it to a lytic compartment, the vacuole/lysosome, where the contents are then degraded. This conserved system is involved not only in the recycling of proteins under starvation conditions but also in the clearance of organelles and aberrant aggregate-prone proteins, digestion of invading pathogens, and so on [1–4]. Genes involved in autophagy were first identified by yeast genetic screenings [5–7]. At present, more than 30 autophagy-related (ATG) genes have been identified in yeast, and of them at least 18 genes are essential for autophagosome formation, a crucial process in autophagy. Most of these 18 genes are conserved in mammals, suggesting that the mechanism of autophagosome formation is basically conserved from yeast to mammals. The 18 Atg proteins can be divided into five groups according to their functions [8, 9]. One group consists of subunits of a class III phosphatidylinositol (PtdIns) 3-kinase complex (hereafter, PtdIns 3-kinase indicates the class III PtdIns 3-kinase). Atg14 and Vps30/Atg6 are two such proteins and are included in this group together with Vps34 and Vps15, catalytic and regulatory subunits, respectively, (the functions of Vps34 and Vps15 in the vacuolar protein sorting pathway have been studied in detail, and; thus, they are not designated as Atg proteins although they are essential for autophagy). Atg14 is a key subunit in determining the function of the PtdIns 3-kinase complex and is the focus of this
PtdIns 3-Kinase Orchestrates Autophagosome Formation in Yeast
Keisuke Obara,Yoshinori Ohsumi
Journal of Lipids , 2011, DOI: 10.1155/2011/498768
Abstract: Eukaryotic cells can massively transport their own cytoplasmic contents into a lytic compartment, the vacuole/lysosome, for recycling through a conserved system called autophagy. The key process in autophagy is the sequestration of cytoplasmic contents within a double-membrane structure, the autophagosome. Autophagosome formation requires the elaborate cooperation of Atg (autophagy-related) proteins and lipid molecules. Phosphorylation of phosphatidylinositol (PtdIns) by a PtdIns 3-kinase, Vps34, is a key step in coordinating Atg proteins and lipid molecules. Vps34 forms two distinct protein complexes, only one of which is involved in generating autophagic membranes. Upon induction of autophagy, PtdIns(3)P, the enzymatic product of PtdIns 3-kinase, is massively transported into the lumen of the vacuole via autophagy. PtdIns(3)P is enriched on the inner membrane of the autophagosome. PtdIns(3)P recruits the Atg18?Atg2 complex and presumably other Atg proteins to autophagic membranes, thereby coordinating lipid molecules and Atg proteins. 1. Membrane Dynamics of Autophagy Eukaryotic cells are equipped with a self-digesting system called macroautophagy (hereafter, autophagy). Using this system, cells can degrade a portion of their cytoplasmic contents, occasionally including organelles, within a lytic compartment called the vacuole or lysosome. Autophagy is considered a primarily cell survival mechanism that enables macromolecules to be recycled under nutrient-limited conditions. However, recent studies have shown that autophagy is a versatile system that is also involved in the clearance of protein aggregate precursors, defense against invading pathogens, cell differentiation, and so forth [1–4]. Autophagy involves unique membrane dynamics, which has been predominantly shown through detailed electron microscopic analyses of starved yeast cells [5, 6]. Upon the induction of autophagy, a cup-shaped isolation membrane emerges in the cytoplasm and elongates to enclose a portion of the cytoplasm. The isolation membrane fuses at its ends to become a closed double-membrane structure called the autophagosome. The autophagosome then fuses with a vacuole or lysosome, where the inner membrane structure is released into the lumen as the autophagic body and is then degraded (Figure 1) [5, 7]. Autophagosome formation is a fundamental process in autophagy that occurs in a variety of situations. Despite its importance, the molecular mechanism of autophagosome formation is still largely unknown. There are unsolved problems including the source of the autophagosome
Sugawara K,Obara Y
岩石力学与工程学报 , 2001,
Abstract: 1 前 言 (1)岩体应力是岩石结构施工过程中至关重要的问题,比如在地下硐室工程中就是如此。地下硐室围岩的力学行为由岩体应力控制,而且岩石结构的稳定性紧密地依赖于岩体应力状态。在岩体应力现场测量中,已有多种方法和仪器被用来测量很多种岩石。以往,Kim博士和Franklin博士所建议的方法包括扁千斤顶法、水力劈裂法以及USBM和CSIRO套孔法[1]。现在,我们这个建议方法中介绍整装锥端钻孔套孔(CCBO)测量应力的技术。 (2)人们总希望通过测量单个钻孔就确定出应力张量,希望使用直径更小一些的微型套…
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