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( Hiroshi Ozaki ) 대한소화기학회 2004 대한소화기학회 춘계학술대회 Vol.2004 No.-
IL-1β, which is produced mainly by macrophages and monocytes, is a proinflammatory cytokine that plays a central role in the inflammation. It has been reported that the concentration of IL-1β in intestinal mucosa increased in patients with Crohns disease and Ulcerative colitis. We observed that, in rat IBD model, resident macrophages distributed in the Auerbachs plexus region expressed sufficient amounts of IL-1β, which could affect smooth muscle contractility in a paracrine manner. In order to elucidate the mechanism of motility disorders frequently observed in IBD, we investigated the long-term effects of IL-1β on rat ileal smooth muscle contractility by using an organ-culture system. When ileal smooth muscle strips were cultured with IL-1β (10ng/mL), contractions elicited by high K+ and carbachol were inhibited in a time-dependent manner. IL-1b more strongly inhibited the carbachol-induced contractions than high K+ with decreasing MLC phosphorylation. In the a-toxin-permeabilized ileal muscle, carbachol with GTP or GTPgS increased the Ca2+ sensitivity of contractile elements, and this G protein-coupled Ca2+-sensitization was significantly reduced in the IL-1β-treated ileum. Among the functional proteins involved in the smooth muscle Ca2+ sensitization, CPI-17 expression was significantly reduced after the culture with IL-1β, while the expressions of RhoA, ROCK-I, ROCK-II, MYPT-1, MLCK, and myosin phosphatase (PP1) were unchanged. Phosphorylation level of CPI-17 by carbachol was low in accordance with decrease in CPI-17 expression due to IL-1β treatment. These results suggest that long-term treatment with IL-1b decreases either CPI-17 expression, which may result in an increase in myosin phosphatase activity to reduce force generation. Based on these findings, we consider IL-1β to be an important mediator of gastrointestinal motility disorders in IBD, and CPI-17 is a key molecule in the decreased smooth muscle contractility due to IL-1β.
Novel Macrolide Actin-inhibitors Isolated from Sea Sponges
Karaki, Hideaki,Ozaki, Hiroshi The Korean Society of Toxicology Korea Environment 2001 Toxicological Research Vol.17 No.-
Several marine toxins with macrolide structure have been found to act on actin. One of these toxins is mycalolide B isolated from the genus Mycale. This compound belongs to macrolide antibiotics and consists of tris-oxazole with strong cytotoxic activity ($IC_{50}$: 10-50 nM for growth of L1210 murine leukemia cells). This compound was found to be an actin-depolymerizing agent with the mode of action distinct from that of the known actin inhibitor, cytochalasin D. Tolytoxin, a macrolide isolated from cyano-bacteria with similar chemical structure to mycalolide B, seems to have similar effect. Another macrolide compound, aplyronine A, showed the effects similar to those of mycalolide B. Although bistheonellide A, a dimeric macrolide, did not show a severing effect, it de polymerized F-actin and sequestered G-actin by forming 1 : 2 complex with G-actins. Swinholide A has a structure and effects similar to those of bistheonel-lide A. In conclusion, mycalolide B, tolytoxin, aplyronine A, bistheonellide A and swinholide A are the members of "actin de polymerizing macrolide" the mechanism of which is different from that of cytochalasin D.halasin D.
Communications Protocol Used in the Wireless Token Rings for Bird-to-Bird
Nakajima, Isao,Juzoji, Hiroshi,Ozaki, Kiyoaki,Nakamura, Noboru Korea Multimedia Society 2018 The journal of multimedia information system Vol.5 No.3
We developed a multicast communication packet radio protocol using a time-sharing tablet system ("wireless token ring") to achieve the efficient exchange of files among packet radio terminals attached to swans. This paper provides an overview of the system and the protocol of the packet communications. The packet device forming the main part of the transceiver developed is the Texas Instruments CC2500. This device consists of one call-up channel and one data transmission channel and could improve error frame correction using FEC (forward error correction) with 34.8 kbps MSK and receiving power of at least -64 dBm (output 1 dBm at distance of 200 m using 3 dBi antenna). A time-sharing framework was determined for the wireless token ring using call sign ordinals to prevent transmission right loss. Tests using eight stations showed that resend requests with the ARQ (automatic repeat request) system are more frequent for a receiving power supply of -62 dBm or less. A wireless token ring system with fixed transmission times is more effective. This communication protocol is useful in cases in which frequency resources are limited; the energy consumed is not dependent on the transmission environment (preset transmission times); multiple terminals are concentrated in a small area; and information (position data and vital data) is shared among terminals under circumstances in which direct communication between a terminal and the center is not possible. The method allows epidemiological predictions of avian influenza infection routes based on vital data and relationships among individual birds based on the network topology recorded by individual terminals. This communication protocol is also expected to have applications in the formation of multiple in vivo micromachines or terminals that are inserted into living organisms.
Tomoharu Inoue,Shin Nagai,Shota Inoue,Masahiro Ozaki,Shohei Sakai,Hiroyuki Muraoka,Hiroshi Koizumi 한국산림과학회 2012 Forest Science And Technology Vol.8 No.2
We investigated the relationships between soil respiration and environmental factors during foliation and defoliation periods in three ecosystems under the same physical–geographical environmental conditions in central Japan. These ecosystems comprised deciduous broad-leaved forest (Quercus crispula dominated, site Q), deciduous needle-leaved forest (Larix kaempferi dominated, site L), and grassland (Zoysia japonica dominated, site Z). Field measurements of soil respiration were made using a closed chamber method with an infrared gas analyzer at monthly intervals in the snow-free seasons from May 2010 to November 2011. Soil respiration began to increase in May, peaked rapidly in summer (July to September), and decreased in November. The seasonal patterns of soil respiration and soil temperature were nearly parallel among the three sites, with one exception, which may have been caused by the decrease in soil water content during summer months (July to September). Although Q_10 values based on the entire measurement period in 2010 were roughly the same as those in 2011 at the three sites, there was a large difference in Q_10 between the foliation and defoliation periods in both years, especially at the two forest sites. These differences among the three sites may be caused by differences in soil temperature dynamics and precipitation activity. To better understand the relationship between soil respiration and environmental factors, continuous observations are needed of soil respiration, environmental factors, and biological activities both below ground and above ground under the same physical–geographical environmental conditions.
자궁평활근의 Carbachol 및 Oxytocin 수축에 있어서의 세포내 Ca<sup>2+</sup> 동원
김보경(Bo-Kyung Kim),정동수(Dong-Su Chung),김윤선(Yoon-Sun Kim),이윤호(Yoon-Ho Lee),용준환(Jun-Hwan Yong),이원창(Won-Chang Lee),Hiroshi Ozaki,Hideaki Karaki,이상목(Sang-Mog Lee) 대한약리학회 1996 대한약리학잡지 Vol.32 No.2
The properties of cytosolic Ca<sup>2+</sup> level([Ca<sup>2+</sup>]<sub>i</sub>) movement of high KCl, carbachol and oxytocin were examined with myometrium isolated from non-pregnant rat(estrus cycle). High concentration of KCl≤23.3mM) induced rhythmic increases in [Ca<sup>2+</sup>]<sub>i</sub> and muscle contraction. However, sustained [Ca<sup>2+</sup>]<sub>i</sub> and contracion were obtained at higher KCl concentration (≥30.3mM) The rhythmic and sustained contraction closely associated with changes in [Ca<sup>2+</sup>]<sub>i</sub> induced by high KCl. Carbachol (3 ~ 30μM generated rhythmic increases with tonic component in [Ca<sup>2+</sup>]<sub>i</sub> and muscle contraction. Myometrial contraction stimulated by carbachol was also closely correlated with change in [Ca<sup>2+</sup>]<sub>i</sub>. And the [Ca<sup>2+</sup>]<sub>i</sub>/contraction relationships were similar when muscle strips were stimulated by high KCl and carbachol. Maximal concentration of carbachol (10μM) and oxytocin(100 nM) increased [Ca<sup>2+</sup>]<sub>i</sub> and contraction which were slightly greater than that of high KCl in non-pregnant myometrium, respectively. However, the [Ca<sup>2+</sup>]<sub>i</sub> and contraction were strongly inhibited by verapamil (10μM), a 1-type Ca<sup>2+</sup> channel blocker, as in the case of high KCl. Additionally, although carbachol further increased [Ca<sup>2+</sup>]<sub>i</sub> and contraction induced by high KCl, these changes also strongly inhibited by application of verapamil. These results suggest that uterotonic agents, carbachol and oxytocin, induced contraction by increase in [Ca<sup>2+</sup>]<sub>i</sub> through Ca<sup>2+</sup> influx than by a regulation of Ca<sup>2+</sup>-sensitization in non-pregnant myometrium.
자궁평활근의 Carbachol 및 Oxytocin 수축에 있어서의 세포내 $Ca^{2+}$ 동원
김보경,정동수,김윤선,이윤호,용준환,이원창,이상목,Kim, Bo-Kyung,Chung, Dong-Su,Kim, Yoon-Sun,Lee, Yoon-Ho,Yong, Jun-Hwan,Lee, Won-Chang,Ozaki, Hiroshi,Karaki, Hideaki,Lee, Sang-Mog 대한약리학회 1996 대한약리학잡지 Vol.32 No.2
The properties of cytosolic $Ca^{2+}$ level$([Ca^{2+}]_i)$ movement of high KCl, carbachol and oxytocin were examined with myometrium isolated from non-pregnant rat(estrus cycle). High concentration of KCl$({\leq}23.3mM)$ induced rhythmic increases in $[Ca^{2+}]_i$ and muscle contraction. However, sustained $[Ca^{2+}]_i$ and contracion were obtained at higher KCl concentration $({\geq}30.3mM)$ The rhythmic and sustained contraction closely associated with changes in $[Ca^{2+}]_i$ induced by high KCl. Carbachol $(3{\sim}30{\mu}M$ generated rhythmic increases with tonic component in $[Ca^{2+}]_i$ and muscle contraction. Myometrial contraction stimulated by carbachol was also closely correlated with change in $[Ca^{2+}]_i$. And the $[Ca^{2+}]_i/contraction$ relationships were similar when muscle strips were stimulated by high KCl and carbachol. Maximal concentration of carbachol $(10{\mu}M)$ and oxytocin(100 nM) increased $[Ca^{2+}]_i$ and contraction which were slightly greater than that of high KCl in non-pregnant myometrium, respectively. However, the $[Ca^{2+}]_i$ and contraction were strongly inhibited by verapamil $(10{\mu}M)$, a 1-type $Ca^{2+}$ channel blocker, as in the case of high KCl. Additionally, although carbachol further increased $[Ca^{2+}]_i$ and contraction induced by high KCl, these changes also strongly inhibited by application of verapamil. These results suggest that uterotonic agents, carbachol and oxytocin, induced contraction by increase in $[Ca^{2+}]_i$ through $Ca^{2+}$ influx than by a regulation of $Ca^{2+}-sensitization$ in non-pregnant myometrium.