T. Koga

Publication List Details

Period

1998 - 2006

Number

135

Co-Authors

Effect of an InP/In$_{0.53}$Ga$_{0.47}$As Interface on Spin-orbit Interaction in In$_{0.52}$Al$_{0.48}$As/In$_{0.53}$Ga$_{0.47}$As Heterostructures (2004)

Lin, Y., Koga, T., Nitta, J.

We report the effect of the insertion of an InP/In$_{0.53}$Ga$_{47}$As Interface on Rashba spin-orbit interaction in In$_{0.52}$Al$_{0.48}$As/In$_{0.53}$Ga$_{0.47}$As quantum wells. A small spin...

Competition between Spin-Orbit Interaction and Zeeman Coupling in Rashba 2DEGs (2004)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Koga, T., Nitta, J.

We investigate systematically how the interplay between Rashba spin-orbit interaction and Zeeman coupling affects the electron transport and the spin dynamics in InGaAs-based 2D electron gases. From...

Competition between spin-orbit interaction and Zeeman coupling in Rashba two-dimensional electron gases (2004)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Koga, T., Nitta, J.

We systematically investigate how the interplay between the Rashba spin-orbit interaction and Zeeman coupling affects the electron transport and the spin dynamics in InGaAs-based 2D electron gases....

Statistical significance of the fine structure in the frequency spectrum of Aharonov-Bohm conductance oscillations (2004)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Koga, T., Nitta, J.

We discuss a statistical analysis of Aharonov-Bohm conductance oscillations measured in a two-dimensional ring, in the presence of Rashba spin-orbit interaction. Measurements performed at different...

Competition between spin-orbit interaction and Zeeman coupling in Rashba two-dimensional electron gases (2004)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Koga, T., Nitta, J.

We systematically investigate how the interplay between the Rashba spin-orbit interaction and Zeeman coupling affects the electron transport and the spin dynamics in InGaAs-based 2D electron gases....

Statistical significance of the fine structure in the frequency spectrum of Aharonov-Bohm conductance oscillations (2004)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Koga, T., Nitta, J.

We discuss a statistical analysis of Aharonov-Bohm conductance oscillations measured in a two-dimensional ring, in the presence of Rashba spin-orbit interaction. Measurements performed at different...

Competition between spin-orbit interaction and Zeeman coupling in Rashba two-dimensional electron gases (2004)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Koga, T., Nitta, J.

We systematically investigate how the interplay between the Rashba spin-orbit interaction and Zeeman coupling affects the electron transport and the spin dynamics in InGaAs-based 2D electron gases....

Statistical significance of the fine structure in the frequency spectrum of Aharonov-Bohm conductance oscillations (2004)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Koga, T., Nitta, J.

We discuss a statistical analysis of Aharonov-Bohm conductance oscillations measured in a two-dimensional ring, in the presence of Rashba spin-orbit interaction. Measurements performed at different...

Statistical significance of fine structure in the frequency spectrum of Aharonov-Bohm conductance oscillations (2003)

Meijer, F. E., Morpurgo, A. F., Klapwijk, T. M., Nitta, J., Koga, T.

We discuss a statistical analysis of Aharonov-Bohm conductance oscillations measured in a two-dimensional ring, in the presence of Rashba spin-orbit interaction. Measurements performed at different...

Low-density polymer thin film formation in supercritical carbon dioxide (2003)

Koga, T., Jerome, J. L., Ge, S., Rafailovich, M. H., Sokolov, J. C., ...

This version is available at the following Publisher URL: http://apl.aip.org

Thermoelectric figure of merit of Bi/Pb_{1-x}Eu_{x}Te superlattices (2000)

Koga, T., Rabin, O., Dresselhaus, M. S.

An enhanced thermoelectric figure of merit Z_{3D}T is predicted for Bi/(111)Pb_{1-x}Eu_{x}Te superlattices. The values of Z_{3D}T obtained for x≈1 superlattices are 2.31, 1.55, and 1.61 at 300,...

Thermoelectric figure of merit of Bi/Pb_{1-x}Eu_{x}Te superlattices (2000)

Koga, T., Rabin, O., Dresselhaus, M. S.

An enhanced thermoelectric figure of merit Z_{3D}T is predicted for Bi/(111)Pb_{1-x}Eu_{x}Te superlattices. The values of Z_{3D}T obtained for x≈1 superlattices are 2.31, 1.55, and 1.61 at 300,...

Thermoelectric figure of merit of Bi/Pb_{1-x}Eu_{x}Te superlattices (2000)

Koga, T., Rabin, O., Dresselhaus, M. S.

An enhanced thermoelectric figure of merit Z_{3D}T is predicted for Bi/(111)Pb_{1-x}Eu_{x}Te superlattices. The values of Z_{3D}T obtained for x≈1 superlattices are 2.31, 1.55, and 1.61 at 300,...

Mechanism of the enhanced thermoelectric power in (111)-oriented n-type PbTe/Pb_{1-x}Eu_{x}Te multiple quantum wells (1999)

Koga, T., Harman, T. C., Cronin, S. B., Dresselhaus, M. S.

A theoretical investigation of the recently observed enhanced thermoelectric power S in (111)-oriented n-type PbTe/Pb1-xEuxTe multiple-quantum-wells (x≃0.09) has been carried out, including both...

Mechanism of the enhanced thermoelectric power in (111)-oriented n-type PbTe/Pb_{1-x}Eu_{x}Te multiple quantum wells (1999)

Koga, T., Harman, T. C., Cronin, S. B., Dresselhaus, M. S.

A theoretical investigation of the recently observed enhanced thermoelectric power S in (111)-oriented n-type PbTe/Pb1-xEuxTe multiple-quantum-wells (x≃0.09) has been carried out, including both...

Mechanism of the enhanced thermoelectric power in (111)-oriented n-type PbTe/Pb_{1-x}Eu_{x}Te multiple quantum wells (1999)

Koga, T., Harman, T. C., Cronin, S. B., Dresselhaus, M. S.

A theoretical investigation of the recently observed enhanced thermoelectric power S in (111)-oriented n-type PbTe/Pb1-xEuxTe multiple-quantum-wells (x≃0.09) has been carried out, including both...

Carrier pocket engineering applied to "strained" Si/Ge superlattices to design useful thermoelectric materials (1999)

Koga, T., Sun, X., Cronin, S. B., Dresselhaus, M. S.

The concept of carrier pocket engineering is applied to strained Si/Ge superlattices to obtain a large thermoelectric figure of merit ZT. In this system, the effect of the lattice strain at the Si/Ge...

Carrier pocket engineering applied to “strained" Si/Ge superlattices to design useful thermoelectric materials (1999)

Koga, T., Sun, X., Cronin, S. B., Dresselhaus, M. S.

The concept of carrier pocket engineering is applied to strained Si/Ge superlattices to obtain a large thermoelectric figure of merit ZT. In this system, the effect of the lattice strain at the Si/Ge...

Carrier pocket engineering applied to “strained" Si/Ge superlattices to design useful thermoelectric materials (1999)

Koga, T., Sun, X., Cronin, S. B., Dresselhaus, M. S.

The concept of carrier pocket engineering is applied to strained Si/Ge superlattices to obtain a large thermoelectric figure of merit ZT. In this system, the effect of the lattice strain at the Si/Ge...

Structural and Mechanical Properties of Fine Composites Prepared by Ti-Si3-N4 Solid State Reactions. (1998)

Koga, T., Mizuno, M., Nagumo, M.

Mechanical alloying of elemental ti and si3n4 powders was conducted by high energy ball milling and solid state reactions were observed to take place during milling. an incubation period for the...

Origin of osteoclasts: mature monocytes and macrophages are capable of differentiating into osteoclasts under a suitable microenvironment prepared by bone marrow-derived stromal cells.

Udagawa, N, Takahashi, N, Akatsu, T, Tanaka, H, Sasaki, T, Nishihara, T, ...

We previously reported that osteoclast-like cells were formed in cocultures of a mouse marrow-derived stromal cell line (ST2) with mouse spleen cells in the presence of 1 alpha, 25-dihydroxyvitamin...

In vitro and in vivo antibacterial activities of CS-834, a novel oral carbapenem.

Fukuoka, T, Ohya, S, Utsui, Y, Domon, H, Takenouchi, T, Koga, T, ...

CS-834 is a novel oral carbapenem antibiotic. This compound is an ester-type prodrug of the active metabolite R-95867. The antibacterial activity of R-95867 was tested against 1,323 clinical isolates...

Role of the capsular polysaccharide-like serotype-specific antigen in resistance of Actinobacillus actinomycetemcomitans to phagocytosis by human polymorphonuclear leukocytes.

Yamaguchi, N, Kawasaki, M, Yamashita, Y, Nakashima, K, Koga, T

Serotype b-specific polysaccharide antigen (SPA) of Actinobacillus actinomycetemcomitans Y4 consists of D-fucose and L-rhamnose. To clarify the role of SPA in phagocytosis of the organism by human...

Actinobacillus actinomycetemcomitans serotype b-specific polysaccharide antigen stimulates production of chemotactic factors and inflammatory cytokines by human monocytes.

Yamaguchi, N, Yamashita, Y, Ikeda, D, Koga, T

Serotype b-specific polysaccharide antigen (SPA) was extracted from whole cells of Actinobacillus actinomycetemcomitans Y4 by autoclaving and purified by chromatography on DEAE-Sephadex A-25 and...

Role of the charged tail in localization of a surface protein antigen of Streptococcus mutans.

Murakami, Y, Yamashita, Y, Nakano, Y, Ito, H O, Yu, H, Koga, T

To make clear the role of the C terminus of a surface protein antigen (PAc) of Streptococcus mutans, stepwise truncations beginning at the C terminus of PAc were performed by utilizing site-directed...

Effects of antibodies against cell surface protein antigen PAc-glucosyltransferase fusion proteins on glucan synthesis and cell adhesion of Streptococcus mutans.

Yu, H, Nakano, Y, Yamashita, Y, Oho, T, Koga, T

Cell surface protein antigen (PAc) and glucosyltransferases (GTFs) produced by Streptococcus mutans are considered to be major colonization factors of the organism, and the inhibition of these two...

Identification of a frameshift mutation resulting in premature termination and loss of cell wall anchoring of the PAc antigen of Streptococcus mutans GS-5.

Murakami, Y, Nakano, Y, Yamashita, Y, Koga, T

Most strains of Streptococcus mutans possess a 190-kDa protein antigen (PAc) on their cell surfaces, while strain GS-5 produces extracellularly a 155-kDa PAc protein. The pac gene of strain GS-5...

Biological function of the dTDP-rhamnose synthesis pathway in Streptococcus mutans.

Tsukioka, Y, Yamashita, Y, Oho, T, Nakano, Y, Koga, T

We have cloned a new gene locus that comprises three genes concerned with the biosynthesis of the serotype c-specific polysaccharide antigen in Streptococcus mutans. The genes encode proteins...

Identification of a fourth gene involved in dTDP-rhamnose synthesis in Streptococcus mutans.

Tsukioka, Y, Yamashita, Y, Nakano, Y, Oho, T, Koga, T

We had isolated three genes (rmlA, rmlB, and rmlC) involved in dTDP-rhamnose synthesis in Streptococcus mutans and found that three genes were insufficient for dTDP-rhamnose synthesis (Y. Tsukioka,...

Interaction between biofilms formed by Pseudomonas aeruginosa and clarithromycin.

Yasuda, H, Ajiki, Y, Koga, T, Kawada, H, Yokota, T

Interactions between bacterial biofilms formed by Pseudomonas aeruginosa and clarithromycin, a macrolide having no anti-P. aeruginosa activity, were investigated. P. aeruginosa incubated for 10 days...

Morphological varieties and host ranges of Vibrio parahaemolyticus bacteriophages isolated from seawater.

Koga, T, Toyoshima, S, Kawata, T

Eighteen bacteriophages lytic for Vibrio parahaemolyticus were isolated from seawater, and their ultrastructure was examined by electron microscopy. Based on the phage morphology, they were...

Genetic control of immune responses in mice to synthetic peptides of a Streptococcus mutans surface protein antigen.

Takahashi, I, Matsushita, K, Nisizawa, T, Okahashi, N, Russell, M W, Suzuki, Y, ...

The immune responses to a cell surface protein antigen (PAc) of Streptococcus mutans and a peptide corresponding to residues 301 to 319 of the protein antigen [PAc(301-319)] in various strains of...

Murine macrophage interleukin-1 release by capsularlike serotype-specific polysaccharide antigens of Actinobacillus actinomycetemcomitans.

Takahashi, T, Nishihara, T, Ishihara, Y, Amano, K, Shibuya, N, Moro, I, ...

Serotype-specific polysaccharide antigens (SPAs) were extracted from whole cells of Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a), Y4 (serotype b), and NCTC 9710 (serotype c) by...

Complete nucleotide sequence of the gene for a surface protein antigen of Streptococcus sobrinus.

Tokuda, M, Okahashi, N, Takahashi, I, Nakai, M, Nagaoka, S, Kawagoe, M, ...

The complete nucleotide sequence of the gene for a cell surface protein antigen (SpaA) of Streptococcus sobrinus MT3791 (serotype g) was determined. The spaA gene consisted of 4,698 bp and coded for...

Surface hydrophobicity, adherence, and aggregation of cell surface protein antigen mutants of Streptococcus mutans serotype c.

Koga, T, Okahashi, N, Takahashi, I, Kanamoto, T, Asakawa, H, Iwaki, M

The pac gene of the serotype c strain Streptococcus mutans MT8148 encodes a cell surface protein antigen (PAc) of approximate 190 kilodaltons. The serotype c strain S. mutans GS-5 does not produce...

Suppression of murine macrophage interleukin-1 release by the polysaccharide portion of Haemophilus actinomycetemcomitans lipopolysaccharide.

Nishihara, T, Koga, T, Hamada, S

Lipopolysaccharide (LPS) was extracted from whole cells of Haemophilus actinomycetemcomitans Y4 by the hot phenol-water procedure. LPS was cleaved into its lipid A and polysaccharide moieties by...

Purification and immunochemical studies of type b carbohydrate antigen of oral Streptococcus milleri.

Yakushiji, T, Inoue, M, Koga, T

The type-specific antigen of serotype b Streptococcus milleri was extracted with trichloroacetic acid from a purified cell wall preparation of the strain NCTC 10708 and then purified on a...

Production of an interleukin-1 inhibitor by cell line P388D1 murine macrophages stimulated with Haemophilus actinomycetemcomitans lipopolysaccharide.

Nishihara, T, Koga, T, Hamada, S

Murine macrophages of the P388D1 cell line stimulated with lipopolysaccharide (LPS) from Haemophilus actinomycetemcomitans Y4 released an interleukin-1 (IL-1) inhibitor, as well as IL-1. Maximal IL-1...

Gamma interferon-mediated increase in the number of Ia-bearing macrophages during infection with Listeria monocytogenes.

Koga, T, Mitsuyama, M, Handa, T, Watanabe, Y, Nomoto, K

The role of gamma interferon (IFN-gamma) in an increase in Ia-bearing macrophages during Listeria monocytogenes infection was studied. The peritoneal macrophages from L. monocytogenes-infected mice...

Immunochemical and structural characterization of a serotype-specific polysaccharide antigen from Actinobacillus actinomycetemcomitans Y4 (serotype b).

Amano, K, Nishihara, T, Shibuya, N, Noguchi, T, Koga, T

A serotype-specific polysaccharide antigen of Actinobacillus actinomycetemcomitans Y4 (serotype b) was extracted from whole cells by autoclaving. The extract was purified by chromatography on...

Augmentation of host defense by a unicellular green alga, Chlorella vulgaris, to Escherichia coli infection.

Tanaka, K, Koga, T, Konishi, F, Nakamura, M, Mitsuyama, M, Himeno, K, ...

Protection against Escherichia coli inoculated intraperitoneally into mice was enhanced by intraperitoneal, intravenous, or subcutaneous administration of a water-soluble, high-molecular-weight...

Biochemical and immunobiological properties of lipopolysaccharide (LPS) from Bacteroides gingivalis and comparison with LPS from Escherichia coli.

Koga, T, Nishihara, T, Fujiwara, T, Nisizawa, T, Okahashi, N, Noguchi, T, ...

Lipopolysaccharides (LPSs) were isolated from Bacteroides gingivalis and Escherichia coli by the phenol-water and butanol-water procedures. The phenol-water-extracted LPS from B. gingivalis 381 was...

Acute joint inflammation in mice after systemic injection of the cell wall, its peptidoglycan, and chemically defined peptidoglycan subunits from various bacteria.

Koga, T, Kakimoto, K, Hirofuji, T, Kotani, S, Ohkuni, H, Watanabe, K, ...

The systemic injection of an aqueous suspension of cell wall or its peptidoglycan (PG)-rich sonicate derived from group A streptococcus and Lactobacillus casei induced acute joint lesions in BALB/c,...

Clinical isolates of Streptococcus mutans serotype c with altered colony morphology due to fructan synthesis.

Okahashi, N, Asakawa, H, Koga, T, Masuda, N, Hamada, S

Streptococcus mutans MT6801 , MT6861 , and MT6879 , which form large mucoid colonies on mitis salivarius agar, were isolated from a mother and her two daughters. These isolates were identified as...

Purification and immunochemical characterization of Streptococcus sanguis ATCC 10557 serotype II carbohydrate antigen.

Koga, T, Okahashi, N, Yamamoto, T, Mizuno, J, Inoue, M, Hamada, S

Cell wall carbohydrate antigen of Streptococcus sanguis ATCC 10557 (serotype II/biotype B) was extracted from purified cell walls by treatment with 5% trichloroacetic acid at 4 degrees C for 8 h. The...

Saliva-binding region of Streptococcus mutans surface protein antigen.

Nakai, M, Okahashi, N, Ohta, H, Koga, T

A 190-kDa surface protein antigen (PAc) of Streptococcus mutans binds to human salivary components. For detection of specific binding of the PAc protein to human salivary components, a simple...

Identification of antigenic epitopes in an alanine-rich repeating region of a surface protein antigen of Streptococcus mutants.

Okahashi, N, Takahashi, I, Nakai, M, Senpuku, H, Nisizawa, T, Koga, T

A surface protein antigen (PAc) of Streptococcus mutans with a molecular mass of 190 kDa is considered to play an important role in the initial attachment of this streptococcus to the tooth surface....

Genetic and functional characterization of the gene cluster specifying expression of Pseudomonas aeruginosa pili.

Koga, T, Ishimoto, K, Lory, S

The genetic organization of the gene cluster containing pilA, the structural gene for type IV pilin of Pseudomonas aeruginosa, as well as the accessory genes pilB, pilC, and pilD, has been studied....

Interaction between clarithromycin and biofilms formed by Staphylococcus epidermidis.

Yasuda, H, Ajiki, Y, Koga, T, Yokota, T

Interactions between clarithromycin and biofilms formed by Staphylococcus epidermidis were investigated by using a clarithromycin-resistant strain. Treatment of the colonization with a relatively low...

Identification of antigenic epitopes in a surface protein antigen of Streptococcus mutans in humans.

Matsushita, K, Nisizawa, T, Nagaoka, S, Kawagoe, M, Koga, T

The reactivities of antibodies in human serum and saliva to a cell surface protein antigen (PAc) of Streptococcus mutans and synthetic peptides covering the PAc molecule were examined. Both an...

Oral immunization with recombinant Streptococcus lactis carrying the Streptococcus mutans surface protein antigen gene.

Iwaki, M, Okahashi, N, Takahashi, I, Kanamoto, T, Sugita-Konishi, Y, Aibara, K, ...

A recombinant Streptococcus lactis strain which carries the structural gene for a surface protein antigen (PAc) of 190,000 daltons from Streptococcus mutans serotype c was constructed for development...

Effect of a glucosyltransferase inhibitor on glucan synthesis and cellular adherence of Streptococcus mutans.

Koga, T, Hamada, S, Murakawa, S, Endo, A

The effects of mutastein, a glucosyltransferase inhibitor derived from an Aspergillus terreus strain, on the glucan synthesis by glucosyltransferases of Streptococcus mutans and sucrose-dependent...

Purification and immunochemical characterization of Streptococcus sanguis serotype I carbohydrate antigen.

Okahashi, N, Koga, T, Akada, H, Hamada, S

The serotype-specific antigen of Streptococcus sanguis ST3 (serotype I, biotype A) was extracted, chromatographically purified, and characterized by immunological and chemical methods. The antigen...

Inhibition of macrophage migration by muramyl peptides.

Nagao, S, Tanaka, A, Yamamoto, Y, Koga, T, Onoue, K, Shiba, T, ...

In the capillary tube migration system a synthetic muramyl dipeptide (MDP; N-acetylmuramyl-L-alanyl-D-isoglutamine), a part of bacterial cell wall peptidoglycans, inhibited the migration of...

IL-12 Production Induced by Agaricus blazei Fraction H (ABH) Involves Toll-like Receptor (TLR)

Kasai, H., He, L. M., Kawamura, M., Yang, P. T., Deng, X. W., Munkanta, M., ...

Agaricus blazei Murill is an edible fungus used in traditional medicine, which has various well-documented medicinal properties. In the present study, we investigated the effects of...

Release of Ca2+ from a non-mitochondrial store site in peritoneal macrophages treated with saponin by inositol 1,4,5-trisphosphate.

Hirata, M, Suematsu, E, Hashimoto, T, Hamachi, T, Koga, T

The effects of inositol 1,4,5-trisphosphate, prepared from human erythrocyte ghosts, on Ca2+ release from intracellular store sites were studied in saponin-treated guinea pig peritoneal macrophages....

Guanine nucleotide binding protein involved in muscarinic responses in the pig coronary artery is insensitive to islet-activating protein.

Sasaguri, T, Hirata, M, Itoh, T, Koga, T, Kuriyama, H

In an attempt to identify the nature of guanine nucleotide binding protein(s) (G-protein) involved in the acetylcholine (ACh)-induced (muscarinic) response of pig coronary-artery smooth muscle, we...