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Search Results: 1 - 10 of 4519 matches for " Hiroshi Umakoshi "
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Enhanced Cytotoxicity for Colon 26 Cells Using Doxorubicin-Loaded Sorbitan Monooleate (Span 80) Vesicles
Keita Hayashi, Tsuyoshi Tatsui, Toshinori Shimanouchi, Hiroshi Umakoshi
International Journal of Biological Sciences , 2013,
Abstract: Span 80 (sorbitan monooleate) vesicles behaved differently from conventional phospholipid vesicles (liposomes) because the former had a more fluid interface. After doxorubicin hydrochloride (DOX) was encapsulated into the Span 80 vesicle (loading efficiency: 63 %), DOX-loaded Span 80 vesicles (DVs) were thereafter added to Colon 26 cells. It was suggested, from the flow cytometric analysis and confocal laser microscopic observation, that DVs directly deliver DOX into the cytoplasm of Colon 26 cells. DVs showed the different delivery manner from the DOX-loaded liposomes (DLs). It is considered that the difference of delivery manner between DVs and DLs resulted in the difference of cytotoxicity (IC50); i.e. IC50 values for DVs and DLs were 5 and > 30 μM, respectively. The results obtained herein would give the fundamental findings which can contribute to the improvement of formulation of conventional liposome-based carrier and its cytotoxicity.
Hydrophobic Properties of tRNA with Varied Conformations Evaluated by an Aqueous Two-Phase System
Keishi Suga, Hibiki Tomita, Seishiro Tanaka, Hiroshi Umakoshi
International Journal of Biological Sciences , 2012,
Abstract: The surface properties of transfer RNA (tRNA) were analyzed using a poly(ethylene glycol)/dextran aqueous two-phase system (ATPS), where the surface net hydrophobicity (HFS) and the local hydrophobicity (LH) were evaluated based on the partition coefficient of tRNA in the ATPS. According to the evaluated HFS values, the surface of the tRNA molecule was hydrophilic at 20° -40 °C, and it became hydrophobic at 50° -80 °C because of the exposure of the intrinsic nucleobases of tRNA. In contrast, the LH values were found to be maximal at 20° -40 °C. The conformation of tRNA was investigated by Raman and circular dichroism (CD) spectroscopies, corroborating the results with the calculated prediction of its secondary structure (Mfold). It was shown that 66% of A-form structure existed at room temperature; the base stacking (θ265) was gradually decreased, and the A-form structure (θ208) was denatured along with a sigmoid curve against the temperature increase; the denatured secondary structures were observed above 50° C by Mfold prediction. The HFS value of the DNA duplex was found to be hydrophilic, compared to that of the single-stranded DNA, indicating that the exposure of nucleobases is a key factor of the hydrophobic properties of nucleotides. We conclude that the hydrophobic property of the tRNA surface was directly affected by its conformational transition.
Oxidative Stress Can Affect the Gene Silencing Effect of DOTAP Liposome in an In Vitro Translation System
Hiroshi Umakoshi, Tomoyuki Tanabe, Keishi Suga, Huong Thi Bui, Toshinori Shimanouchi, Ryoichi Kuboi
International Journal of Biological Sciences , 2011,
Abstract: Oxidative stress can affect in vitro GFP expression through its control of the gene silencing effect of the liposome prepared by 1,2-dioleoyl-3-trimethyl-ammonium propane (DOTAP). The gene silencing effect of cationic DOTAP liposome in in vitro GFP expression, especially focusing on its translation process, and the effects of oxidative stress on its silencing effect were investigated. GFP expression, initiated by mRNA, was found to be thoroughly inhibited in the presence of DOTAP liposome at concentration of more than 2.5 mM, though its inhibitory effect was reduced in the presence of hydrogen peroxide. The analyses of (i) the interaction of mRNA with DOTAP, (ii) the chemical structure of DOTAP, and (iii) the membrane fluidity of DOTAP liposome imply the possible role of gene expression by the liposome membrane and stress conditions.
Active Targeting to Osteosarcoma Cells and Apoptotic Cell Death Induction by the Novel Lectin Eucheuma serra Agglutinin Isolated from a Marine Red Alga
Keita Hayashi,Peter Walde,Tatsuhiko Miyazaki,Kenshi Sakayama,Atsushi Nakamura,Kenji Kameda,Seizo Masuda,Hiroshi Umakoshi,Keiichi Kato
Journal of Drug Delivery , 2012, DOI: 10.1155/2012/842785
Abstract: Previously, we demonstrated that the novel lectin Eucheuma serra agglutinin from a marine red alga (ESA) induces apoptotic cell death in carcinoma. We now find that ESA induces apoptosis also in the case of sarcoma cells. First, propidium iodide assays with OST cells and LM8 cells showed a decrease in cell viability after addition of ESA. With 50? g/ml ESA, the viabilities after 24 hours decreased to 54.7 ± 11.4% in the case of OST cells and to 41.7 ± 12.3% for LM8 cells. Second, using fluorescently labeled ESA and flow cytometric and fluorescence microscopic measurements, it could be shown that ESA does not bind to cells that were treated with glycosidases, indicating importance of the carbohydrate chains on the surface of the cells for efficient ESA-cell interactions. Third, Span 80 vesicles with surface-bound ESA as active targeting ligand were shown to display sarcoma cell binding activity, leading to apoptosis and complete OST cell death after 48 hours at 2? g/ml ESA. The findings indicate that Span 80 vesicles with surface-bound ESA are a potentially useful drug delivery system not only for the treatment of carcinoma but also for the treatment of osteosarcoma. 1. Introduction Osteosarcoma has one of the worst prognosis among all malignant tumors. Before 1970, the 5-year survival rate of the treated patients was only about 20% [1, 2]. The treatment of osteosarcoma currently involves surgical resection in combination with neoadjuvant chemotherapy. Despite advances in the neoadjuvant chemotherapy and in limb-salvage surgery, the disease-free survival rate still remains poor for patients with metastatic, recurrent, or unresectable osteosarcoma. Thus, novel selective therapeutic approaches against osteosarcoma are highly required. Previously, we found that the novel lectin Eucheuma serra agglutinin (ESA), which was successfully isolated by Kawakubo et al. [3] from the marine red alga Eucheuma serra, specifically binds to carcinoma cell lines of human adenocarcinoma, human cervical squamous cell carcinoma, and marine adenocarcinoma but not to normal human fibroblasts or lymphocytes [4]. We also revealed, that the specific binding of ESA to carcinoma cells is based on specific interactions between ESA and the unique sugar chains of high mannose type on the surface of the carcinoma cells [4]. In a more recent study, Hori et al. [5] investigated the specific interactions between ESA and various unique sugar chains of high mannose type in detail. Furthermore, we successfully elaborated the basis for a novel type of drug delivery system (DDS) for cancer
Plastic deformation behaviour and deformation substructure in Al-rich TiAl single crystals deformed at high temperatures
K Hayashi, T Nakano and Y Umakoshi
Science and Technology of Advanced Materials , 2001,
Abstract: Plastic deformation behaviour in Ti–54.7 at.%Al and Ti–58.0 at.%Al single crystals was examined around and above the anomalous strengthening peak temperature (Tp) focusing on the effect of Al5Ti3 superstructure. The Al5Ti3 superstructure developed in the L10 matrix of Ti–58.0 at.%Al, and the size of the Al5Ti3 phase once increased during annealing at 800°C and then decreased with increasing temperature, while no significant evidence of the Al5Ti3 particles was obtained in Ti–54.7 at.%Al from TEM observation although diffuse scattering corresponding to the spots for the Al5Ti3 superstructure was observed. The transition of slip plane for lang110] ordinary dislocations from {111} to {110) and/or (001) occurred at and above Tp due to anisotropy of anti-phase boundary energies on {111}, {110) and (001) in the Al5Ti3 superstructure. Anomalous strengthening is related to the development of this superstructure which may assist the cross-slip of some parts of lang110] ordinary dislocations onto {110) and/or (001) resulting in the formation of dragging points to the motion of the dislocations.
Formation of nanocrystalline structure during electron irradiation induced crystallization in amorphous Fe–Zr–B alloys
T. Nagase, Y. Umakoshi and N. Sumida
Science and Technology of Advanced Materials , 2002,
Abstract: Effect of electron irradiation on the crystallization and phase stability of Fe88Zr9B3 and Fe71Zr9B20 amorphous alloys was examined. Electron irradiation at an accelerated voltage of 2000 kV was performed at room temperature. The Fe71Zr9B20 alloy showed a wide supercooled liquid region and the ΔTx value was 71 K, while no glass transition was observed in Fe88Zr9B3 alloy. The amorphous phase in Fe–Zr–B alloys was not stable under irradiation and crystallization from the amorphous phase was accelerated by the irradiation. Nanocrystalline structure composed of α-Fe and cubic-Fe2Zr was formed in Fe88Zr9B3 alloy by irradiation induced crystallization, while no nanoscale precipitates of intermetallic compounds were formed during annealing. In Fe71Zr9B20 alloy, the formation of nanocrystalline precipitates was also confirmed by irradiation induced crystallization, although the formation of nanocrystalline structure had not been realized in high B concentration Fe–Zr–B alloys by annealing. These new results show that electron irradiation is effective in producing a new nanocrystalline structure.
Behaviour of Ru(bpy)2+3 on the Surface of Water-Soluble Single-Walled Carbon Nanotubes on Adding Other Cations  [PDF]
Hiroshi Shioyama
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2012, DOI: 10.4236/jsemat.2012.22015
Abstract: Behaviour of excited Ru(bpy)2+3 bound to the surface of water-soluble single-walled carbon nanotubes on addition of other cations have been investigated by measuring Ru(bpy) luminescence. In contrast to what was observed with a solution containing rod-like aggregation particles of Nafion, we found that Ru(bpy)2+3 has a stronger attraction than that of other cations to the sulfonic groups on the carbon nanotubes. Such a difference is attributed to the unique micro-environmental characteristics of the molecular assemblies.
Extension of Smoothed Particle Hydrodynamics (SPH), Mathematical Background of Vortex Blob Method (VBM) and Moving Particle Semi-Implicit (MPS)  [PDF]
Hiroshi Isshiki
American Journal of Computational Mathematics (AJCM) , 2014, DOI: 10.4236/ajcm.2014.45036
Abstract: SPH has a reasonable mathematical background. Although VBM and MPS are similar to SPH, their ma-thematical backgrounds seem fragile. VBM has some problems in treating the viscous diffusion of vortices but is known as a practical method for calculating viscous flows. The mathematical background of MPS is also not sufficient. Not with standing, the numerical results seem reasonable in many cases. The problem common in both VBM and MPS is that the space derivatives necessary for calculating viscous diffusion are not estimated reasonably, although the treatment of advection is mathematically correct. This paper discusses a method to estimate the above mentioned problem of how to treat the space derivatives. The numerical results show the comparison among FDM (Finite Difference Method), SPH and MPS in detail. In some cases, there are big differences among them. An extension of SPH is also given.
The Effective Chiral Model of Quantum Hadrodynamics Applied to Nuclear Matter and Neutron Stars  [PDF]
Hiroshi Uechi
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.32017

We review theoretical relations between macroscopic properties of neutron stars and microscopic quantities of nuclear matter, such as consistency of hadronic nuclear models and observed masses of neutron stars. The relativistic hadronic field theory, quantum hadrodynamics (QHD), and mean-field approximations of the theory are applied to saturation properties of symmetric nuclear and neutron matter. The equivalence between mean-field approximations and Hartree approximation is emphasized in terms of renormalized effective masses and effective coupling constants of hadrons. This is important to prove that the direct application of mean-field (Hartree) approximation to nuclear and neutron matter is inadequate to examine physical observables. The equations of state (EOS), binding energies of nuclear matter, self-consistency of nuclear matter, are reviewed, and the result of chiral Hartree-Fock \"\"approximation is shown. Neutron stars and history of nuclear astrophysics, nuclear model and nuclear matter, possibility of hadron and hadron-quark neutron stars are briefly reviewed. The hadronic models are very useful and practical for understanding astrophysical phenomena, nuclear

Patterns in Stroke Occurrence on Warm Days in Winter by Associations Analysis  [PDF]
Hiroshi Morimoto
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.512074
Abstract: There is increasing interest in the effects of meteorological factors on stroke occurrence. A number of studies have found that cold exposure was a trigger to the onset of cerebral infarction in winter. It was believed that the case of stroke occurrence on warm days in winterwas just a coincidence and negligible. The main objective of this study was to offer the evidence against the above belief. We aimed to find typical patterns among stroke occurrences in case the weather became warmer in winter. Associations analysis was conducted using daily data of emergency transport at Nagoya City in Japan. Typical patterns were identified among risky stroke occurrences even for the case that the weather became warmer in winter. These findings will contribute to an accurate forecast of stroke occurrence in winter.
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