The effects of the appearance rate of stimulus on the rats' auditory evoked potentials

The mismatch negativity (MMN) is a component of the auditory event-related brain potential which is elicited by the infrequent stimuli within the repeated frequent stimuli. The stimulus sequence which generates the MMN has the property which elicit following two automatic processes: (1) the neural model for frequent stimulus is established, and difference between incoming stimulus and the model is detected (Cowan, Winkler, Teder, & Naatanen, 1993) and/or (2) the neural model for the context, infrequent as figure and frequent as ground, is established, and the attention to figure is called. The Papez circuit is known to be critical for memory because the demage of these regions cause the memory deficit. In this study, auditory evoked potentials for frequent and infrequent tones in the above stimulus sequence were recorded from the regions of the Papez circuit (dentate gyrus, mammillary body, anterior thalamus) and cortices (auditory and entorhinal). The purpose of this study is to examine following three : (1) whether the components which correspond to the automatic processes appear or not in the regions of the Papez circuit; and if these components appear, (2) the temporal relation between the information processing in the Papez circuit and that in cortical area by comparing the latencies of processing in the Papez circuit and that in cortical area by comparing the latencies of components; (3) the effects of stimulus appearance rate on those components in the Papez circuit. In the regions of the Papez circuit, the amplitudes of the positive component peaking at about 30 and 70msec for infrequent tones were higher than those for frequent tones. But in the cortical area, only the amplitude of positive component peaking at about 70msec for infrequent tones was higher than those for frequent tones. These phenomenon disappeared as frequent and infrequent tones came to be more equal in the stimulus appearance rate. The results suggested that the information processing which based on the neural model of the frequent standard stimulus and/or on the context of global stimulus sequence occurred in the cortical area and the Papez circuit in parallel

第一原理計算に基づくペロブスカイト型酸水素化物の理論予測

学位の種別: 課程博士審査委員会委員 : （主査）東京大学准教授 藤堂 真治, 東京大学教授 福谷 克之, 東京大学教授 瀧川 仁, 東京大学准教授 松田 巌, 東京大学准教授 杉野 修University of Tokyo(東京大学

R-Process Nucleosynthesis in MHD Jet Explosions of Core-Collapse Supernovae

We investigate $r$-process nucleosynthesis during the magnetohydrodynamical (MHD) explosion of supernova in a massive star of 13 $M_{\odot}$. Contrary to the case of the spherical explosion, jet-like explosion due to the combined effects of the rotation and magnetic field lowers the electron fraction significantly inside the layers above the iron core. We find that the ejected material of low electron fraction responsible for the $r$-process comes out from the silicon rich layer of the presupernova model. This leads to the production up to the third peak in the solar $r$-process elements. We examine whether the fission affects the $r$-process paths by using the full nuclear reaction network with both the spontaneous and $\beta$-delayed fission included. Moreover, we pay particular attention how the mass formula affects the $r$-process peaks with use of two mass formulae. It is found that both formulae can reproduce the global abundance pattern up to the third peak though detailed distributions are rather different. We point out that there are variations in the $r$-process nucleosynthesis if the MHD effects play an important role in the supernova explosion.Comment: 19 pages with 7 figures, submitted to Ap

Vitrification of Germinal Vesicle Stage Oocytes

In order to cryopreserve germinal vesicle (GV) stage oocytes, we first need to develop a novel container for keeping large quantities of GV oocytes, because of collecting them as cumulus oocytes complexes (COCs) that have bigger size and larger volume than oocytes themselves, and second modify a protocol for optimizing vitrification of them. In this mini-review, we describe our recent progress for attaining these objectives. When 65 bovine COCs having GV oocytes could be placed on a sheet of nylon mesh, and plunged directly into liquid nitrogen for vitrification, the recovery rate was significantly higher compared with that in 15 ones on the electron microscope (EM) grid as a control, followed by obtaining the resultant cleavage and developmental rates after in vitro fertilization and culture (IVFC) without significant difference. Using bovine and murine oocytes, we found that a step-wise manner to expose them with the vitrification solution increased rates of in vitro maturation, subsequent development to blastocysts and hatching/hatched blastocysts after IVFC. Our results show that nylon mesh is an alternative material for cryopreserving large quantities of bovine GV oocytes, and that a step-wise exposure to cryoprotectants may have befit for decreasing disadvantage during vitrification

Palmitate induces reactive oxygen species production and β-cell dysfunction by activating nicotinamide adenine dinucleotide phosphate oxidase through Src signaling.

[Aims/Introduction]Chronic hyperlipidemia impairs pancreatic β-cell function, referred to as lipotoxicity. We have reported an important role of endogenous reactive oxygen species (ROS) overproduction by activation of Src, a non-receptor tyrosine kinase, in impaired glucose-induced insulin secretion (GIIS) from diabetic rat islets. In the present study, we investigated the role of ROS production by Src signaling in palmitate-induced dysfunction of β-cells. [Materials and Methods]After rat insulinoma INS-1D cells were exposed to 0.6 mmol/L palmitate for 24 h (palmitate exposure); GIIS, ROS production and nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity were examined with or without exposure to10 μmol/L 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2), a Src inhibitior, for 30 or 60 min. [Results]Exposure to PP2 recovered impaired GIIS and decreased ROS overproduction as a result of palmitate exposure. Palmitate exposure increased activity of NOX and protein levels of NOX2, a pathological ROS source in β-cells. Palmitate exposure increased the protein level of p47phox, a regulatory protein of NOX2, in membrane fraction compared with control, which was reduced by PP2. Transfection of small interfering ribonucleic acid of p47phox suppressed the augmented p47phox protein level in membrane fraction, decreased augmented ROS production and increased impaired GΙIS by palmitate exposure. In addition, exposure to PP2 ameliorated impaired GIIS and decreased ROS production in isolated islets of KK-Ay mice, an obese diabetic model with hyperlipidemia. [Conclusions]Activation of NOX through Src signaling plays an important role in ROS overproduction and impaired GΙIS caused by chronic exposure to palmitate, suggesting a lipotoxic mechanism of β-cell dysfunction of obese mice

Book Recommendation Based on Library Loan Records and Bibliographic Information

AbstractIn order to show the effectiveness of using (a) library loan records and (b) information about book contents as a basis for book recommendations, we entered various data into a support vector machine (SVM), used it to recommend books to subjects, and asked them for evaluations of the recommendations that were given. The data that we used were (1) confidence and support with an association rule that was based on the loan records, (2) similarities between book titles, (3) matches/mismatches between the Nippon Decimal Classification (NDC) categories of the books, and (4) similarities between the outlines of the books in the BOOK Database. The subjects were 32 students who belonged to T University. The books that we recommended and the loan records that we used were obtained from the T University Library. The results showed that the combinations of (1), (2), (3) and (1), (2) were rated more favorably by the subjects than the other combinations. However, the books that were recommended by Amazon were rated even more favorably by the subjects. This is a topic for further research