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Presynaptic Mechanism Underlying Regulation of Transmitter Release by G Protein Coupled Receptors
Tomoyuki Takahashi,Yoshinao Kajikawa,Masahiro Kimura,Naoto Saitoh,Tetsuhiro Tsujimoto 대한생리학회-대한약리학회 2004 The Korean Journal of Physiology & Pharmacology Vol.8 No.2
A variety of G protein coupled receptors (GPCRs) are expressed in the presynaptic terminals of central and peripheral synapses and play regulatory roles in transmitter release. The patch-clamp whole-cell recording technique, applied to the calyx of Held presynaptic terminal in brainstem slices of rodents, has made it possible to directly examine intracellular mechanisms underlying the GPCR-mediated presynaptic inhibition. At the calyx of Held, bath-application of agonists for GPCRs such as GABA<SUB>B</SUB> receptors, group III metabotropic glutamate receptors (mGluRs), adenosine A<SUB>1</SUB> receptors, or adrenaline α2 receptors, attenuate evoked transmitter release via inhibiting voltage-activated Ca<SUP>2</SUP> currents without affecting voltage-activated K<SUP></SUP> currents or inwardly rectifying K<SUP></SUP> currents. Furthermore, inhibition of voltage-activated Ca<SUP>2</SUP> currents fully explains the magnitude of GPCR-mediated presynaptic inhibition, indicating no essential involvement of exocytotic mechanisms in the downstream of Ca<SUP>2</SUP> influx. Direct loadings of G protein βγ subunit (Gβγ) into the calyceal terminal mimic and occlude the inhibitory effect of a GPCR agonist on presynaptic Ca<SUP>2</SUP> currents (Ip<SUB>Ca</SUB>), suggesting that Gβγmediates presynaptic inhibition by GPCRs. Among presynaptic GPCRs glutamate and adenosine autoreceptors play regulatory roles in transmitter release during early postnatal period when the release probability (p) is high, but these functions are lost concomitantly with a decrease in p during postnatal development.
Presynaptic Mechanism Underlying Regulation of Transmitter Release by G Protein Coupled Receptors
Takahashi, Tomoyuki,Kajikawa, Yoshinao,Kimura, Masahiro,Saitoh, Naoto,Tsujimoto, Tetsuhiro The Korean Society of Pharmacology 2004 The Korean Journal of Physiology & Pharmacology Vol.8 No.2
A variety of G protein coupled receptors (GPCRs) are expressed in the presynaptic terminals of central and peripheral synapses and play regulatory roles in transmitter release. The patch-clamp whole-cell recording technique, applied to the calyx of Held presynaptic terminal in brainstem slices of rodents, has made it possible to directly examine intracellular mechanisms underlying the GPCR-mediated presynaptic inhibition. At the calyx of Held, bath-application of agonists for GPCRs such as $GABA_B$ receptors, group III metabotropic glutamate receptors (mGluRs), adenosine $A_1$ receptors, or adrenaline ${\alpha}2$ receptors, attenuate evoked transmitter release via inhibiting voltage-activated $Ca^{2+}$ currents without affecting voltage-activated $K^+$ currents or inwardly rectifying $K^+$ currents. Furthermore, inhibition of voltage-activated $Ca^{2+}$ currents fully explains the magnitude of GPCR-mediated presynaptic inhibition, indicating no essential involvement of exocytotic mechanisms in the downstream of $Ca^{2+}$ influx. Direct loadings of G protein ${\beta}{\gamma}$ subunit $(G{\beta}{\gamma})$ into the calyceal terminal mimic and occlude the inhibitory effect of a GPCR agonist on presynaptic $Ca^{2+}$ currents $(Ip_{Ca})$, suggesting that $G{\beta}{\gamma}$ mediates presynaptic inhibition by GPCRs. Among presynaptic GPCRs glutamate and adenosine autoreceptors play regulatory roles in transmitter release during early postnatal period when the release probability (p) is high, but these functions are lost concomitantly with a decrease in p during postnatal development.
Modified Open-Door Laminoplasty Using a Ceramic Spacer and Suture Fixation for Cervical Myelopathy
Tomoyuki Ozawa,Tomoaki Toyone,Ryutaro Shiboi,Kunimasa Inada,Yasuhiro Oikawa,Kazuhisa Takahashi,Seiji Ohtori,Gen Inoue,Masayuki Miyagi,Tetsuhiro Ishikawa,Toshiyuki Shirahata,Yoshifumi Kudo,Katsunori In 연세대학교의과대학 2015 Yonsei medical journal Vol.56 No.6
Purpose: To introduce a new simple technique using suture anchors and ceramic spacers to stabilize the elevated laminae in open-door cervical laminoplasty. Although ceramic spacers were placed in the opened laminae and fixed with nylon threads in this series, it was occasionally difficult to fix the nylon threads to the lateral mass. Materials and Methods: Study 1: A preliminary study was conducted using a suture anchor system. Sixteen consecutive patients who underwent surgery for cervical myelopathy were prospectively examined. Study 2: The second study was performed prospectivelyto evaluate the feasibility of this new technique based on the result of the preliminary study. Clinical outcomes were examined in 45 consecutive patients [cervical spondylotic myelopathy (CSM)] and 43 consecutive patients (OPLL). The Japanese Orthopedic Association scoring system (JOA score), axial neck pain, and radiological findings were analyzed. Results: 1) In one case, re-operation was necessary due to dislodgement of the ceramic spacer following rupture of the thread. 2) In all patients, postoperative CT scans showed that the anchors were securely inserted into the bone. In the CSM group, the average JOA score improved from 9.5 points preoperatively to 13.3 at follow-up (recovery 51%). In the OPLL group, the average JOA score improvedfrom 10.1 (5–14) points preoperatively to 14.4 (11–16) at follow-up (recovery 62%). There were no serious complications. Conclusion: The use of the suture anchor system made it unnecessary to create a hole in the lateral mass and enabled reliable and faster fixation of the HA spacers in open-door laminoplasty.
( Kenichiro Takahashi ),( Shigeki Bamba ),( Masahiro Kawahara ),( Atsushi Nishida ),( Osamu Inatomi ),( Masaya Sasaki ),( Tomoyuki Tsujikawa ),( Ryoji Kushima ),( Mitsushige Sugimoto ),( Katsuyuki Kit 대한장연구학회 2018 Intestinal Research Vol.16 No.4
The objective of this study was to evaluate the magnified endoscopic findings in the diagnosis of follicular lymphoma in the small intestine in comparison with those of intestinal follicular lymphoma and lymphangiectasia. Four patients with follicular lymphoma and 3 with lymphangiectasia in the small intestine were retrospectively analyzed. A prototype magnifying single-balloon enteroscope was used. The findings of the intestinal follicular lymphoma and lymphangiectasia were retrospectively analyzed to determine the magnified endoscopic findings of follicular lymphoma in the small intestine. Opaque white granules were observed in 3 of the 4 patients with follicular lymphoma. Magnified narrow-band imaging (NBI) of the opaque white granules showed stretched microvessels, which had a diminutive tree-like appearance. The remaining patient had no opaque white granules and only displayed whitish villi. Magnified NBI observation of the whitish villi revealed the absence of marginal villus epithelium, which was confirmed by histology. The magnified NBI enteroscopy revealed the diminutive tree-like appearance on the opaque white granules and the absence of marginal villus epithelium of the whitish villi in intestinal follicular lymphoma. These findings may be useful in diagnosing follicular lymphoma. (Intest Res 2018;16:628-634)
Foxf2 represses bone formation via Wnt2b/β-catenin signaling
Tanaka Tomoyuki,Takahashi Akira,Kobayashi Yutaka,Saito Masanori,Xiaolong Sun,Jingquan Chen,Ito Yoshiaki,Kato Tsuyoshi,Ochi Hiroki,Sato Shingo,Yoshii Toshitaka,Okawa Atsushi,Carlsson Peter,Inose Hiroyu 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
Differentiation of mesenchymal stem cells (MSCs) into osteoblasts is a critical process for proper skeletal development and acquisition/maintenance of bone mass. However, since this regulatory mechanism has not yet been fully elucidated, the treatment of severe osteoporosis and fractures is a challenge. Here, through a comprehensive analysis of gene expression during the differentiation of MSCs into osteoblasts, we show that the forkhead transcription factor Foxf2 is a crucial regulator of this process. Foxf2 expression transiently increased during MSC osteoblastic differentiation. Overexpression of Foxf2 in MSCs inhibited osteoblastic differentiation, and conversely, knockdown of Foxf2 expression promoted this process. Osteoprogenitor-specific Foxf2 knockout mice developed a high bone mass phenotype due to increased bone formation. RNA-seq analysis and molecular experiments revealed that Foxf2 regulation of bone formation is mediated by Wnt2b. Knockdown of Foxf2 in mouse femurs enhanced bone regeneration in vivo. FOXF2 expression was correlated with hip bone mineral density in postmenopausal women with low bone mass. Finally, inhibition of FOXF2 promoted osteoblastic differentiation of human MSCs. This study uncovers a critical role of Foxf2 in the differentiation of MSCs into osteoblasts and provides insight into the pathogenesis associated with bone-related diseases such as osteoporosis and nonunion after fracture
Mitigation of Load Frequency Fluctuation Using a Centralized Pitch Angle Control of Wind Turbines
Junqiao, Liu,Rosyadi, Marwan,Takahashi, Rion,Tamura, Junji,Fukushima, Tomoyuki,Sakahara, Atsushi,Shinya, Koji,Yosioka, Kazuki Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.1
In this paper an application of centralized pitch angle controller for fixed speed wind turbines based wind farm to mitigate load frequency fluctuation is presented. Reference signal for the pitch angle of each wind turbine is calculated by using proposed centralized control system based on wind speed information. The wind farm in the model system is connected to a multi machine power system which is composed of 4 synchronous generators and a load. Simulation analyses have been carried out to investigate the performance of the controller using real wind speed data. It is concluded that the load frequency of the system can be controlled smoothly.