Time filter

Source Type

Kagoshima, Japan

, or Kadai is a Japanese national university located in Kagoshima, Kagoshima Prefecture, Japan. There are three campuses: Shimoarata: Faculty of Fisheries Sakuragaoka: Faculty of Medicine Korimoto: Faculties of Engineering, Science, Agriculture, Education, Humanities and Literature The University's Nansei-Toko Observatory for Earthquakes and Volcanoes is represented on the national Coordinating Committee for Earthquake Prediction. Wikipedia.

Matsuguchi T.,Kagoshima University
Current Medicinal Chemistry | Year: 2012

Mast cells are best known as central effector cells in IgE-mediated type I allergic diseases including asthma and hay fever. An increasing amount of evidence, however, has demonstrated that mast cells are sentinel cells playing a critical role in host defense against invading microbes. Mast cells are located immediately beneath the epithelial surfaces exposed to the outer environment, such as genitourinary and gastrointestinal tracts, skin, and airways. This review discusses recent studies on the critical roles of mast cells in host defense against Gram-negative bacterial infection. Mast cells are equipped with multiple receptors detecting the invading Gram-negative bacteria in both direct (opsonin-independent) and indirect (opsonin-dependent) mechanisms. The former includes Toll-like receptors (TLRs), CD48, and nucleotide-binding oligomerization (NOD) proteins, while the latter includes Fcγ receptors (FcγRs) and complement receptors. In addition to the detecting systems, mast cells are also armed with versatile tools to combat and kill Gram-negative bacteria. In response to the recognition of the Gram-negative bacterial infection, mast cells secrete various types of mediators which either regulate host immune system or directly attack the bacteria. Mast cells can also phagocytize and subsequently display the bacterial antigens on their cell surfaces. Moreover, recent findings have revealed the formation of extra-cellular traps by mast cells. Finally this review will especially focus on recent findings on LPS signaling in mast cells, both the functional outcome and the molecular mechanisms. © 2012 Bentham Science Publishers.

Kadokawa J.-I.,Kagoshima University
Chemical Reviews | Year: 2011

Precision polysaccharide synthesis by enzymatic catalysis are overviewed that include significant studies on the enzymatic synthesis of oligosaccharides. As the enzymatic glycosylations proceed with highly controlled stereo- and regioselectivities, the poly- and oligosaccharides with well-defined structure have efficiently been synthesized. Due to the production of the structurally defined saccharide chains by the enzymatic catalysis, the strict control of their higher-ordered assemblies is achieved. The enzymatic polysaccharide synthesis is found to have advantage over the conventional chemical process. These include the reactions proceed under the mild conditions in aqueous media and renewable resources from natural and related sources can be employed as the substrates of the reactions.

Wada K.,Kagoshima University
Astrophysical Journal | Year: 2012

We propose a plausible mechanism to explain the formation of the so-called obscuring tori around active galactic nuclei (AGNs) based on three-dimensional hydrodynamic simulations including radiative feedback from the central source. The X-ray heating and radiation pressure on the gas are explicitly calculated using a ray-tracing method. This radiation feedback drives a "fountain," that is, a vertical circulation of gas in the central few to tens parsecs. Interaction between the non-steady outflows and inflows causes the formation of a geometrically thick torus with internal turbulent motion. As a result, the AGN is obscured for a wide range of solid angles. In a quasi-steady state, the opening angles for the column density toward a black hole <1023cm-2 are approximately ±30° and ±50° for AGNs with 10% and 1% Eddington luminosity, respectively. Mass inflows through the torus coexist with the outflow and internal turbulent motion, and the average mass accretion rate to the central parsec region is 2 × 10-4 ∼ 10-3 M⊙ yr -1; this is about 10times smaller than accretion rate required to maintain the AGN luminosity. This implies that relatively luminous AGN activity is intrinsically intermittent or that there are other mechanisms, such as stellar energy feedback, that enhance the mass accretion to the center. © 2012. The American Astronomical Society. All rights reserved.

Wada K.,Kagoshima University
Astrophysical Journal | Year: 2015

Active galactic nuclei (AGNs) are believed to be obscured by an optical thick "torus" that covers a large fraction of solid angles for the nuclei. However, the physical origin of the tori and the differences in the tori among AGNs are not clear. In a previous paper based on three-dimensional radiation-hydorodynamic calculations, we proposed a physics-based mechanism for the obscuration, called "radiation-driven fountains," in which the circulation of the gas driven by central radiation naturally forms a thick disk that partially obscures the nuclear emission. Here, we expand this mechanism and conduct a series of simulations to explore how obscuration depends on the properties of AGNs. We found that the obscuring fraction fobs for a given column density toward the AGNs changes depending on both the AGN luminosity and the black hole mass. In particular, fobs for NH ≥ 1022 cm-2 increases from ∼0.2 to ∼0.6 as a function of the X-ray luminosity LX in the LX = 1042-44 erg s-1 range, but fobs becomes small (∼0.4) above a luminosity (∼1045 erg s-1). The behaviors of fobs can be understood by a simple analytic model and provide insight into the redshift evolution of the obscuration. The simulations also show that for a given LAGN, fobs is always smaller (∼0.2-0.3) for a larger column density (NH ≥ 1023 cm-2). We also found cases that more than 70% of the solid angles can be covered by the fountain flows. © 2015. The American Astronomical Society. All rights reserved..

Kadokawa J.-i.,Kagoshima University | Kobayashi S.,Kyoto Institute of Technology
Current Opinion in Chemical Biology | Year: 2010

Using biocatalysts as enzymes for in vitro polymer synthesis is a relatively new (third) stream that has become popular in the past two decades, following a first stream using catalysts of acids, bases, radical species, and so on, used since 1920s, and a second stream using catalysts of transition metals and rare metals since 1950s. Enzymatic catalysis is environmentally benign, yet allows the synthesis of various natural and unnatural polymers that have well-defined structures with controlled stereochemistry, regioselectivity, and chemoselectivity. This review will focus on recent developments in enzyme-catalyzed polymer synthesis in the areas of polysaccharides, polyesters, and polyaromatics, as well as polymer modification. © 2009 Elsevier Ltd. All rights reserved.

Discover hidden collaborations