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Search Results: 1 - 10 of 1144 matches for " Naokado Ikeda "
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Transporter-Mediated Drug Interaction Strategy for 5-Aminolevulinic Acid (ALA)-Based Photodynamic Diagnosis of Malignant Brain Tumor: Molecular Design of ABCG2 Inhibitors
Toshihisa Ishikawa,Kenkichi Takahashi,Naokado Ikeda,Yoshinaga Kajimoto,Yuichiro Hagiya,Shun-ichiro Ogura,Shin-ichi Miyatake,Toshihiko Kuroiwa
Pharmaceutics , 2011, DOI: 10.3390/pharmaceutics3030615
Abstract: Photodynamic diagnosis (PDD) is a practical tool currently used in surgical operation of aggressive brain tumors, such as glioblastoma. PDD is achieved by a photon-induced physicochemical reaction which is induced by excitation of protoporphyrin IX (PpIX) exposed to light. Fluorescence-guided gross-total resection has recently been developed in PDD, where 5-aminolevulinic acid (ALA) or its ester is administered as the precursor of PpIX. ALA induces the accumulation of PpIX, a natural photo-sensitizer, in cancer cells. Recent studies provide evidence that adenosine triphosphate (ATP)-binding cassette (ABC) transporter ABCG2 plays a pivotal role in regulating the cellular accumulation of porphyrins in cancer cells and thereby affects the efficacy of PDD. Protein kinase inhibitors are suggested to potentially enhance the PDD efficacy by blocking ABCG2-mediated porphyrin efflux from cancer cells. It is of great interest to develop potent ABCG2-inhibitors that can be applied to PDD for brain tumor therapy. This review article addresses a pivotal role of human ABC transporter ABCG2 in PDD as well as a new?approach of quantitative structure-activity relationship (QSAR) analysis to design potent ABCG2-inhibitors.
Sentinel Lymph Node Biopsy as Guidance for Lateral Neck Dissection in Patients with Papillary Thyroid Carcinoma  [PDF]
Yoshifumi Ikeda
Surgical Science (SS) , 2011, DOI: 10.4236/ss.2011.22012
Abstract: Introduction: The surgical management of lateral lymph nodes in differentiated thyroid carcinoma is controversies. Therefore, we analyzed whether sentinel lymph nodes (SLN) biopsy of the first draining nodes in the jugulo-carotid chain is an accurate technique to select patients with true-positive but nonpalpable lymph nodes for selective lateral node dissection. Materials and Methods: From January 2009 to December 2009, 12 patients with solitary papillary carcinoma measuring 2 cm by ultrasonography were included in this study. After the thyroid gland was exposed to avoid injuring the lateral thyroid lymphatic connection, approximately 0.2 ml of 5mg/ml indocyanine green was injected into the parenchyma of upper and lower thyroid gland. Some stained lymph nodes in the jugulo-carotid chain could be identified following the stained lymphatic duct and dissected as the SLN. After that, thyroidectomy with modified neck dissection was performed. Results: The mean tumor size was 22.1 ± 4.6 mm. Identification and biopsy of stained SLN in the ipsilateral jugulo-carotid chain was successful in all 12 cases. In 6 cases, histopathological analysis of SLNs revealed metastases of the papillary thyroid carcinoma. Among them, 2 cases had additional metastatic lymph nodes in the ipsilateral compartment. Of the 6 patients who had negative lymph node metastasis (LNM) in SLNs, all patients had negative LNM in the ipsilateral compartment. Conclusions: The method may be helpful in the detection of true-positive but nonpalpable lymph nodes and may support a decision to perform a selective lateral node dissection in patients with papillary thyroid carcinoma.
The Function of Roots of Tea Plant (Camellia sinensis) Cultured by a Novel Form of Hydroponics and Soil Acidification  [PDF]
Kieko Saito, Masahiko Ikeda
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.35078
Abstract: A novel form of hydroponic culture was employed to explore the physiological function of roots of a tea plant (Camellia sinensis). The pH of the nutrient solution with an actively growing tea plant decreased during cultivation. Furthermore, no oxalic acid, tartaric acid, malic acid or citric acid, all possible factors in acidification, was detected in the nutrient solution of a growing plant. A proton pump inhibitor suppressed the acidification of the solution. Soil acidification might have been accelerated with a proton released from ammoniacal nitrogen preferentially for the growth, suggesting the specific mechanism of tea plant as a functional food.
Regional Mapping of Vertical Hydraulic Gradient Using Uncertain Well Data: A Case Study of the Toyohira River Alluvial Fan, Japan  [PDF]
Yoshitaka Sakata, Ryuji Ikeda
Journal of Water Resource and Protection (JWARP) , 2013, DOI: 10.4236/jwarp.2013.58083
Abstract:

Vertical hydraulic gradient (VHG) provides detailed information on 3D groundwater flows in alluvial fans, but its regional mapping is complicated by a lack of piezometer nests and uncertainty in conventional well data. Especially, determining representative depth of well screen in each well is problematic. Here, a VHG map of the Toyohira River alluvial fan, Sapporo, Japan, is constructed based on groundwater table elevation (GTE), using available well-data of various screen lengths and depths. The water-level data after 1988, when subway constructions are mostly completed in the city, are divided into those of shallow wells (≤20 m deep), and those of deep wells (>20 m deep). First, the GTE map is generated by kriging interpolation of shallow well data with topographic drift. Next, the individual VHG value of each deep well is calculated using its top, middle, and bottom elevations of the screen depths, respectively. The VHG maps of three cases are then obtained using neighborhood kriging. The VHG map of the bottom screen depths has proven most valid by cross-validation. The VHG map better visualizes that downward flows of groundwater are predominant over the fan. Positive area of VHG is mostly vanished around the fan-toe, indicating urbanization effect such as artificial withdrawals. A negative peak of VHG corresponds to recharge area, and is seen along the distinct losing section in the river. The negative peak also expands upstream to the fan-apex where a basement is suddenly depressed.

Exchange Rate and Current Account Dynamics with Habits over Consumption and Money Holdings  [PDF]
Ichiro Gombi, Shinsuke Ikeda
Modern Economy (ME) , 2013, DOI: 10.4236/me.2013.47051
Abstract:

Incorporating two independent habits over consumption and money holdings into a small country model, we examine the adjustment dynamics of the current account and the exchange rate to expansionary monetary and fiscal shocks under two alternative policy regimes: (1) the endogenous income transfer regime; and (2) the endogenous fiscal spending regime. In response to the shocks under regime (1), the exchange rate depreciates on impact and in the long run whereas it appreciates (depreciates) in transition if preferences for real money balances exhibit distant (adjacent) complementarity. Under regime (2), the consumption habits and the monetary habits jointly generate possibly non-monotonic current account dynamics. An induced increase in fiscal spending in regime (2) can generate a current account surplus in the case where the monetary habits exhibit strong distant complementarity.

Fabrication and Characterization of Porous Silica Monolith by Sintering Silica Nanoparticles  [PDF]
Hiroshi Ikeda, Shigeru Fujino
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2017, DOI: 10.4236/jmmce.2017.53009
Abstract: This paper aims to fabricate over centimeter size of porous silica monolith having meso-pores with large surface area. A precursor of porous silica monolith was obtained by sintering a monolithic SiO2-poly (vinyl alcohol) (PVA) nanocomposite at 600oC-1100oC. The sintering behavior was examined by means of Raman spectroscopy and a porosimetry. The PVA of the SiO2-PVA nanocomposite was combusted below 600oC, subsequently the silica nanoparticles of the nanocomposite were sintered above 900oC. The Raman spectroscopy suggested that amorphous structure of the porous silica monolith obtained above 1000oC was similar to that of a silica glass. The BET surface area and pore radius of the porous silica monolith decreased with increasing sintering temperature. These values were tailored in the range of ca. 0-291 m2.g-1 and 5-25 nm, respectively, by controlling the sintering temperature and time. The fabricated porous-silica monolith was translucent or opaque porous-silica depending on the pore size.
Should We Enhance or Restrict Technological Diffusion from Major to Minor Firms?  [PDF]
Hideki Nakamura, Takeshi Ikeda
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.811146
Abstract: This study examines how technological diffusion from a major firm to a minor firm affects social welfare via R & D competition in an asymmetric Cournot duopoly. We assume that the minor firm can decrease its production cost because of the spillover effect arising through R & D by the major firm. R & D by the minor firm depends on the free-riding effect and a taking-away effect that removes market share from the major firm. If given a low R & D cost, both firms invest in R & D with an appropriate level of technological diffusion, we can obtain a high level of social welfare. However, an increase in the level of technological diffusion could make the major firm abandon R & D activity. Given a high R & D cost, a high level of welfare can be obtained only with a low level of technological diffusion because the potential presence of technological diffusion easily disrupts R & D by the major firm.
One-dimensional Kac model of dense amorphous hard spheres
Harukuni Ikeda,Atsushi Ikeda
Physics , 2015, DOI: 10.1209/0295-5075/111/40007
Abstract: We introduce a new model of hard spheres under confinement for the study of the glass and jamming transitions. The model is an one-dimensional chain of the $d$-dimensional boxes each of which contains the same number of hard spheres, and the particles in the boxes of the ends of the chain are quenched at their equilibrium positions. We focus on the infinite dimensional limit ($d \to \infty$) of the model and analytically compute the glass transition densities using the replica liquid theory. From the chain length dependence of the transition densities, we extract the characteristic length scales at the glass transition. The divergence of the lengths are characterized by the two exponents, $-1/4$ for the dynamical transition and $-1$ for the ideal glass transition, which are consistent with those of the $p$-spin mean-field spin glass model. We also show that the model is useful for the study of the growing length scale at the jamming transition.
Evaluating Sleeping and Waking States of Infants: Consistency of Actigraph and Observational Data  [PDF]
Rie Nakamura Ikeda, Kiyoko Fukai
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.65053
Abstract: The objective was to evaluate sleeping and waking states of infants <6 months old. The design of study was comparing video-recorded and actigraphic data. Participants were thirteen healthy 3- to 5-month-old infants. At their homes, subjects wore an ankle actigraph for 1 h and were videotaped simultaneously. We performed per-minute analysis of video data using the method for observing newborns developed by Brazelton. Video and actigraphic data were compared each minute. The total concordance rate was 93.5%. Sleep/wake identification by actigraphy and visual observation correspond closely for infants.
Atomic force microscopy and Raman scattering spectroscopy studies on heat-induced fibrous aggregates of β-lactoglobulin
Shinya Ikeda
Spectroscopy: An International Journal , 2003, DOI: 10.1155/2003/920321
Abstract: Nanometer-thick fibrous aggregates of β-lactoglobulin alone and its mixture with other globular proteins were formed by heating aqueous solutions at pH 2 with maintaining an effective level of electrostatic repulsion among denatured protein molecules. In atomic force microscopy (AFM) images, these fibrous aggregates appeared to be fairly uniform in width and height and composed of strings of globular elements. Fibrous aggregates formed in β-lactoglobulin individual systems were only slightly thicker than the size of the native β-lactoglobulin monomer, while those formed in the presence of other globular proteins were more than twice thicker, suggesting that different species of globular proteins were incorporated into each individual fibrous aggregate in the mixed systems. At neutral pH, aggregates were generally composed of ellipsoidal primary particles much larger than the size of the monomer, suggesting that aggregation proceeds in two steps at neutral pH. Molecular structural changes probed by Raman scattering spectroscopy revealed that considerable fractions of β-sheet structures remained to be folded during the formation of fibrous aggregates but α-helix structures were partially lost. It was also suggested that a limited extent of hydrophobic interactions among heat-denatured protein molecules is required for the fibrous aggregation.
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