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Oku, Yusuke,Kurokawa, Kenji,Matsuo, Miki,Yamada, Sakuo,Lee, Bok-Luel,Sekimizu, Kazuhisa American Society for Microbiology 2009 Journal of Bacteriology Vol.191 No.1
<B>ABSTRACT</B><P>Lipoteichoic acid (LTA) is one of two anionic polymers on the surface of the gram-positive bacterium <I>Staphylococcus aureus</I>. LTA is critical for the bacterium-host cell interaction and has recently been shown to be required for cell growth and division. To determine additional biological roles of LTA, we found it necessary to identify permissive conditions for the growth of an LTA-deficient mutant. We found that an LTA-deficient <I>S. aureus</I> Δ<I>ltaS</I> mutant could grow at 30°C but not at 37°C. Even at the permissive temperature, Δ<I>ltaS</I> mutant cells had aberrant cell division and separation, decreased autolysis, and reduced levels of peptidoglycan hydrolases. Upshift of Δ<I>ltaS</I> mutant cells to a nonpermissive temperature caused an inability to exclude Sytox green dye. A high-osmolarity growth medium remarkably rescued the colony-forming ability of the Δ<I>ltaS</I> mutant at 37°C, indicating that LTA synthesis is required for growth under low-osmolarity conditions. In addition, the Δ<I>ltaS</I> mutation was found to be synthetically lethal with the Δ<I>tagO</I> mutation, which disrupts the synthesis of the other anionic polymer, wall teichoic acid (WTA), at 30°C, suggesting that LTA and WTA compensate for one another in an essential function.</P>
Dietary Fiber and Large Bowel Cancer
Tsuneyuki Oku 한국식품영양과학회 1996 한국식품영양과학회지 Vol.25 No.3
Large bowel cancer correlates tightly to dietary factors such as dietary fiber and fat. Dietary fiber prevents the large bowel cancer in different modes of action which depend upon physicochemical and fermentable properties. Water-soluble fiber is fermented easily by intestinal microbes producing short chain fatty acids ; in contrast, water-insoluble fiber occurs effectively more rapid transit time due to greater bulk of gut content, though it is unfermentable. Not only short chain fatty acid is utilized in the proximal and distal colon as primary energy source, but also it lowers pH in the colon to normalize cellular differentiation and helps to stimulate peristaltic movement by acting as an osmotic laxative. In particular, butyric acid may also regulate gene expression and cell growth, though it is an important respiratory fuel for the colonocyte. Since dietary fiber and non-digestible oligosaccharides are the major source of butyric acid, this provides a possible link between dietary fiber and oligosaccharide and prevention of large bowel cancer. But, as with many links between dietary fiber and large bowel cancer, a direct casual association has not been established. In addition, RDA of dietary fiber which is 20~25g/day for adult Japanese, appears to be reasonable for the defecation once daily and the prevention of large bowel cancer.
Experiment on closed-loop subspace model identification of an unstable underactuated system
Hiroshi Oku,Shun Ushida 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
We report an experimental result on closed-loop subspace model identification of a cart-inverted pendulum system. Such a system as mentioned here is known as a typical unstable under actuated system, which is impossible of open-loop identification. Furthermore, any conventional SISO identification is not applicable to this systemsince this system is of single input and two outputs. Therefore, in this case, closed-loop subspace model identification is the only way of identification. Bode diagrams will show that the reisfairly good agreement between an identified model obtained from closed-loop subspace identification and an initial model used for a stabilizing feedback controller at the frequency important for control of this inverted pendulum.
Keiko Oku 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.10
The Kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae) constructs webs over leaf surfaces and usually lives under the webs. T. kanzawai produces two types of excreta, black and yellow pellets, and uses its webs as a place for excretion. T. kanzawai also uses its webs as a refuge when the predatory mite, Neoseiulus womersleyi (Acari: Phytoseiidae) is present. To clarify what factors deter N. womersleyi from foraging on T. kanzawai webs, I experimentally examined the effects of T. kanzawai excreta on its own fitness (fecundity) and the foraging behaviour of N. womersleyi. When the excreta of T. kanzawai was put on leaf surfaces, the fecundity of T. kanzawai adult females was reduced by the black but not the yellow faecal pellets. On the other hand, predation by N. womersleyi was reduced by the yellow but not the black pellets. Although this effect of the yellow pellets on N. womersleyi did not last on leaf surfaces, it deterred N. womersleyi from staying on the webs regardless of its freshness. These results suggest that T. kanzawai deposits black pellets on webs to avoid its negative effect on their own fitness, and yellow pellets are deposited on webs to reduce the risk of predation.
Formation and characterization of MEH-PPV/PCBM-based bulk heterojunction solar cells
Takeo Oku,Syuichi Nagaoka,Atsushi Suzuki,Kenji Kikuchi,Yasuhiko Hayashi,Hayato Sakuragi,Tetsuo Soga 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6
Polymer/fullerene bulk heterojunction solar cells with poly[2-methoxy-5-(20-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV), zinc-phthalocyanine (ZnPc) and 6,6-phenyl C61-butyric acid methyl ester (PCBM), were produced and characterized. A device based on MEH-PPV and PCBM provided better efficiency, fill factor and short-circuit current compared to those of a device on MEH-PPV(ZnPc) and PCBM. The solar cells with a MEH-PPV and PCBM structure showed a higher photoresponse in the range of 300 to 60 nm. The energy levels of the molecules were calculated and are discussed. Polymer/fullerene bulk heterojunction solar cells with poly[2-methoxy-5-(20-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV), zinc-phthalocyanine (ZnPc) and 6,6-phenyl C61-butyric acid methyl ester (PCBM), were produced and characterized. A device based on MEH-PPV and PCBM provided better efficiency, fill factor and short-circuit current compared to those of a device on MEH-PPV(ZnPc) and PCBM. The solar cells with a MEH-PPV and PCBM structure showed a higher photoresponse in the range of 300 to 60 nm. The energy levels of the molecules were calculated and are discussed.
Hisae Oku,Fumika Kitagawa,Yoshihisa Kato,Tomoya Miyashita,Masaomi Hara,Toshitaka Minetoki,Shizuo Yamada 한국식품영양과학회 2021 Journal of medicinal food Vol.24 No.5
We evaluated the effects of unripe mandarin orange (Citrus unshiu) extract powder (unripe mandarin extract powder [UMEP]) treated with subcritical water on allergic diseases by using animal models. High performance liquid chromatography (HPLC) analysis revealed that subcritical water is a more effective solvent than alcohol and hot water, as it quickly extracted approximately 90% of the functional compounds narirutin (1) and hesperidin (2) from whole fruits. Repeated oral administration of UMEP significantly reversed the peripheral blood flow decline observed during the promotion of allergies after sensitization with the antigen, hen egg-white lysozyme (HEL). UMEP also significantly inhibited compound 48/80-induced scratching behavior in HEL-sensitized mice, which are more sensitive to itching stimuli than are normal mice, without suppressing locomotor activity. In addition, repeated oral administration of UMEP in ovalbumin-challenged guinea pigs significantly suppressed the late phase of nasal airway resistance. This study provides evidence that the subcritical water extract powder of unripe C. unshiu fruit is an effective anti-allergic functional food.