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Search Results: 1 - 10 of 3141 matches for " Minoru Saito "
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Study on the Optimal Interval of Monitoring Following Gastric Polyp
Minoru Kawaguchi,Toshihiko Saito
Diagnostic and Therapeutic Endoscopy , 2000, DOI: 10.1155/dte.6.59
Abstract: The present study was conducted to determine how long hyperplastic polyps (HPs) and fundic gland hyperplastic polyps (FGPs) should be endoscopically followed up. Our findings showed that in the case of FGPs, yearly endoscopy is not required and it is sufficient to repeat X-ray and compare films with those obtained in the previous year. In contrast, yearly follow-up by endoscopy is necessary in the case of HPs.
Fluorescent Voltage Imaging Technique for the Measurement of Molluscan Neural Activities  [PDF]
Yuuta Hamasaki, Makoto Hosoi, Shogo Nakada, Tomoya Shimokawa, Minoru Saito
Open Journal of Biophysics (OJBIPHY) , 2013, DOI: 10.4236/ojbiphy.2013.31A007
Abstract:

The electrophysiological methods using microelectrodes are not appropriate for the simultaneous measurement of neural activities of many neurons. To overcome the difficulty, the fluorescent imaging technique using voltage sensitive dyes can be a powerful technique. The voltage sensitive dyes, however, generally exhibit a relatively small change in their fluorescence intensities, resulting in a low S/N ratio. Additionally, they often exhibit photobleaching and phototoxity. We have therefore improved the fluorescent voltage imaging technique by using a LED as the light source and an electron multiplying (EM)-CCD camera as the fluorescence detector. In this study, we applied our imaging system for the measurement of two kind of molluscan neural activities; one of which is involved in the olfactory processing of the land slug Limax valentianus and the other is involved in the feeding rhythm of the pond snail Lymnaea stagnalis. The system enabled us to measure the neural activities for a long time with a high speed and a high S/N ratio, and the obtained results showed some new physiological findings.

Simultaneous Measurement of Neural Activities of Acute Mouse Hippocampal Slices Using Multi-Electrode Array System and Laser Confocal Calcium Imaging  [PDF]
Yuuta Hamasaki, Natsumi Haba, Naoki Iwata, Yoshiki Uno, Minoru Saito
Journal of Behavioral and Brain Science (JBBS) , 2017, DOI: 10.4236/jbbs.2017.72008
Abstract: Recently, non-invasive, real-time and multi-point measurement of neural activities has become possible by using a multi-electrode array (MEA). Another method for multi-point measurement is the fluorescent imaging technique using voltage indicator dyes or calcium indicator dyes. Especially, calcium imaging using fluorescent calcium indicator dyes is often more useful, because they exhibit larger changes in the fluorescence intensity than voltage indicator dyes and their fluorescence changes can be detect easily. Additionally, calcium signals play key roles in the brain function, such as the long-term potentiation (LTP) in the hippocampus, and calcium imaging can be a powerful tool to elucidate the brain function. In this study, we constructed a measurement apparatus combining the MEA system and laser confocal calcium imaging and simultaneously measured electric signals and calcium signals in acute mouse hippocampal slices. The obtained results showed the availability of the present method.
The binding site for acute corticosterone effects on N-methyl-D-aspartate receptor-mediated Ca2+ signals in mouse hippocampal slices  [PDF]
Hiromi Osanai, Akiyoshi Suzuki, Yoshimasa Komatsuzaki, Hideo Mukai, Suguru Kawato, Minoru Saito
Journal of Biophysical Chemistry (JBPC) , 2011, DOI: 10.4236/jbpc.2011.24050
Abstract: We have examined acute effects of corticosterone (CORT) on N-methyl-D-aspartate (NMDA) receptor-mediated Ca2+ signals in adult mouse hippocampal slices. We found so far that the 30 min preincubation of CORT induced a signifcant decrease of the peak amplitude of NMDA-induced Ca2+ elevation in the CA1 region. The membrane non-permeable bovine serum albumin-conjugated CORT also induced a similar effect in the CA1 region. Therefore the acute CORT effects should be induced via putative surface CORT receptors. A possible candidate is a classical intracellular glucocorticoid receptor (GR). To confirm this speculation, we here examined the effects of dexamethasone (DEX: an agonist of GR) and CORT with RU38486 (an antagonist of GR) on NMDA-induced Ca2+ signals. As a result, DEX induced a similar effect to the suppressive CORT effect in the CA1 region, and RU38486 inhibited the suppressive CORT effect. These results indicate that the surface CORT receptor should be GR bound to plasma mem- brane.
Coherency Evaluation of Spatiotemporal Neural Activities in the Molluscan Olfactory Center Applying Extracellular Recording with Wavelet Analysis  [PDF]
Yuuta Hamasaki, Tomoya Shimokawa, Kohei Ishida, Yoshimasa Komatsuzaki, Satoshi Watanabe, Minoru Saito
Open Journal of Biophysics (OJBIPHY) , 2013, DOI: 10.4236/ojbiphy.2013.34035
Abstract: The procerebrum (PC) of the land slug Limax is the olfactory center involved in olfactory discrimination and learning. In the PC, an oscillation of local field potential (LFP) with 0.5 - 1 Hz is observed by electrophysiological extracellular recording. Additionally, spatiotemporal neural activities in the PC have been examined using optical recordings. However, extracellular recording is preferable to measure neural activities for a long time with a high speed, while it is not abundant in spatial information. In this study, we therefore attempted to elicit spatial information from extracellular recording. For this purpose, we evaluated spatial information included in the LFP compared with the spatiotemporal neural activities measured by the fluorescent voltage imaging. As a result, aversive odors induced the coherent spatiotemporal neural activities in the PC, and the increase in coherency was observed as a change in the LFP waveform. It was also evaluated as a decrease in entropy by analyzing the LFP oscillation patterns and wavelet analysis. Thus, although the LFP provides only one series of signals, the coherency of the spatiotemporal neural activities in the PC can be evaluated by applying extracellular recording with wavelet analysis.
Spatiotemporal Neural Activity Changes in the Molluscan Olfactory Center Specifically Induced by Innately Aversive and In Vitro Aversively Conditioned Odors  [PDF]
Kohei Ishida, Momo Murata, Koharu Hashiguchi, Yoshimasa Komatsuzaki, Satoshi Watanabe, Minoru Saito
Journal of Behavioral and Brain Science (JBBS) , 2018, DOI: 10.4236/jbbs.2018.85018
Abstract: In the procerebrum (PC), the olfactory center, of the land slug Limax, an oscillation of local field potential (LFP) with 0.5 - 1 Hz is observed by electrophysiological extracellular recording. The oscillation has a phase delay along the distal-proximal axis, resulting in the propagation of waves from the distal to proximal region. One important advantage of nervous systems of mollusks such as Limax is that their nervous systems in vitro retain several types of computational properties found in vivo (e.g. learning and memory). A previous study showed that the LFP frequency in the PC of Limax increased specifically in response to innately aversive and in vitro aversively conditioned odors. In the present study, we examined spatiotemporal neural activity changes induced in the PC by those odors using the fluorescent voltage imaging technique. The results showed that innately aversive (onion and hexanol) and in vitro aversively conditioned (carrot, which is innately attractive) odors specifically induced an increase in propagation speed of the neural activity in the PC, while innately attractive odors did not induce it. The results also suggested that the avoidance behavior by those odors might be induced by the increase of propagation speed and the following increases in the discharges of the partial nerve that transmits the motor output.
Minimum Wage, Public Investment, Economic Growth  [PDF]
Minoru Watanabe
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.35048
Abstract: This paper considers the relationship between economic growth and minimum wage. Minimum wage helps reduce poverty and maintain a minimum standard of living. However, it is also claimed that minimum wage has a negative effect on employment and GDP. This paper develops a simple two-period overlapping generation model with three economic policies, minimum wage, unemployment benefit, and public investment that improves labor productivity. The government imposes tax on firms to finance public capital and unemployment benefit under a balanced budget. We show that economic growth is promoted with an increase in minimum wage and the ratio of public investment to tax revenue.
Corticosterone Induces Rapid Spinogenesis via Synaptic Glucocorticoid Receptors and Kinase Networks in Hippocampus
Yoshimasa Komatsuzaki, Yusuke Hatanaka, Gen Murakami, Hideo Mukai, Yasushi Hojo, Minoru Saito, Tetsuya Kimoto, Suguru Kawato
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034124
Abstract: Background Modulation of dendritic spines under acute stress is attracting much attention. Exposure to acute stress induces corticosterone (CORT) secretion from the adrenal cortex, resulting in rapid increase of CORT levels in plasma and the hippocampus. Methodology/Principal Findings Here we demonstrated the mechanisms of rapid effect (~1 h) of CORT on the density and morphology of spines by imaging neurons in adult male rat hippocampal slices. The application of CORT at 100–1000 nM induced a rapid increase in the density of spines of CA1 pyramidal neurons. The density of small-head spines (0.2–0.4 μm) was increased even at low CORT levels (100–200 nM). The density of middle-head spines (0.4–0.5 μm) was increased at high CORT levels between 400–1000 nM. The density of large-head spines (0.5–1.0 μm) was increased only at 1000 nM CORT. Co-administration of RU486, an antagonist of glucocorticoid receptor (GR), abolished the effect of CORT. Blocking a single kinase, such as MAPK, PKA, PKC or PI3K, suppressed CORT-induced enhancement of spinogenesis. Blocking NMDA receptors suppressed the CORT effect. Conclusions/Significance These results imply that stress levels of CORT (100–1000 nM) drive the spinogenesis via synaptic GR and multiple kinase pathways.
A new mouse model for renal lesions produced by intravenous injection of diphtheria toxin A-chain expression plasmid
Shingo Nakamura, Masuo Terashima, Natsuko Kikuchi, Minoru Kimura, Tadaaki Maehara, Akira Saito, Masahiro Sato
BMC Nephrology , 2004, DOI: 10.1186/1471-2369-5-4
Abstract: An expression plasmid carrying the cytomegalovirus enhancer/chicken β-actin promoter linked to a DT-A gene was mixed with lipid (FuGENE?6) and the resulting complexes were intravenously injected into adult male B6C3F1 mice every day for up to 6 days. After final injection, the kidneys of these mice were sampled on day 4 and weeks 3 and 5.H-E staining of the kidney specimens sampled on day 4 revealed remarkable alterations in glomerular compartments, as exemplified by mesangial cell proliferation and formation of extensive deposits in glomerular basement membrane. At weeks 3 and 5, gradual recovery of these tissues was observed. These mice exhibited proteinuria and disease resembling sub-acute glomerulonephritis.Repeated intravenous injections of DT-A expression plasmid DNA/lipid complex caused temporary abnormalities mainly in glomeruli of mouse kidney. The disease in these mice resembles sub-acute glomerulonephritis. These DT-A gene-incorporated mice will be useful as animal models in the fields of nephrology and regenerative medicine.Glomerular injury has been thought to play an important role in progression to renal failure. To search for therapeutic drugs for renal failure, it is of importance to use renal disease models in animals. There are several experimentally-induced models in animals, including subtotal nephrectomized animals, [1,2] snake venom-induced glomerulonephritis models, [3] and glomerulonephritis models produced by tail-vein injection of antiserum [4-7]. Transgenic mice overexpressing megsin, a novel protein of Kunitz-type plasminogen activator inhibitor, under a ubiquitous promoter system CAG [8] (composed of cytomegalovirus enhancer and chicken β-actin promoter) are reported to exhibit glomerular nephritis associated with mesangial proliferation, accumulation of extracellular matrix and deposits of IgG [9]. Experimentally induced models are always accompanied by fluctuation in degree of manifestation of disease among individuals, and much time
Evaluation of Pharyngeal Function between No Bolus and Bolus Propofol Induced Sedation for Advanced Upper Endoscopy
Shinsuke Kiriyama,Hiroshi Naitoh,Minoru Fukuchi,Takaharu Fukasawa,Kana Saito,Yuichi Tabe,Hayato Yamauchi,Tomonori Yoshida,Hiroyuki Kuwano
Diagnostic and Therapeutic Endoscopy , 2014, DOI: 10.1155/2014/248097
Abstract: This study aimed to assess pharyngeal function between no bolus and bolus propofol induced sedation during gastric endoscopic submucosal dissection. A retrospective study was conducted involving consecutive gastric cancer patients. Patients in the no bolus group received a 3?mg/kg/h maintenance dose of propofol after the initiation of sedation without bolus injection. All patients in the bolus group received the same maintenance dose of propofol with bolus 0.5?mg/kg propofol injection. Pharyngeal functions were evaluated endoscopically for the first 5?min following the initial administration of propofol. Fourteen patients received no bolus propofol induction and 13 received bolus propofol induction. Motionless vocal cords were observed in 2 patients (14%) in the no bolus group and 3 (23%) in the bolus group. Trachea cartilage was not observed in the no bolus group but was apparent in 6 patients (46%) in the bolus group ( ). Scope stimulated pharyngeal reflex was observed in 11 patients (79%) in the no bolus group and in 3 (23%) in the bolus group ( ). Propofol induced sedation without bolus administration preserves pharyngeal function and may constitute a safer sedation method than with bolus. 1. Introduction Early detection and diagnosis may improve outcome and survival in patients with gastric cancer. The endoscopic submucosal dissection (ESD) technique was developed to resect large neoplasms en bloc and to reduce the risk of recurrence [1]. However, ESD generally takes longer than conventional endoscopic mucosal resection (EMR) [2], so adequate moderate and deep sedations are necessary [3]. Recently, propofol sedation administered by anaesthesiologists or gastroenterologists has gained popularity in endoscopic procedures [4–7]. Propofol is a short-acting sedative, that is, an agonist of the γ-aminobutyricacid receptor in the central nervous system [8]. Effectiveness of propofol induced sedation during endoscopic procedures is under evaluation. It has been reported that monitored propofol sedation is safer than sedation with midazolam [3, 9, 10]; however, cases of respiratory depression including reduced oxygen saturation during propofol sedation have been reported [11–13]. Bolus administration of propofol is often performed at the initial stage of sedation; however, bolus induction might be regarded as one of the causes of respiratory depression. Although the relationship between propofol and respiratory depression has been reported [14], the direct association with propofol and pharyngeal function is thus far not known. Therefore, we evaluated this
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