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468 results on '"Fujiwara, Koichi"'

8. Development of an epileptic seizure prediction algorithm using R–R intervals with self-attentive autoencoder

Author

Ode, Rikumo, Fujiwara, Koichi, Miyajima, Miho, Yamakawa, Toshikata, Kano, Manabu, Jin, Kazutaka, Nakasato, Nobukazu, Sawai, Yasuko, Hoshida, Toru, Iwasaki, Masaki, Murata, Yoshiko, Watanabe, Satsuki, Watanabe, Yutaka, Suzuki, Yoko, Inaji, Motoki, Kunii, Naoto, Oshino, Satoru, Khoo, Hui Ming, Kishima, Haruhiko, and Maehara, Taketoshi

Published
2023
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9. Dual targeting of DDX3 and eIF4A by the translation inhibitor rocaglamide A

Author

Chen, Mingming, Asanuma, Miwako, Takahashi, Mari, Shichino, Yuichi, Mito, Mari, Fujiwara, Koichi, Saito, Hironori, Floor, Stephen N, Ingolia, Nicholas T, Sodeoka, Mikiko, Dodo, Kosuke, Ito, Takuhiro, and Iwasaki, Shintaro

Subjects
Cancer, Genetics, Benzofurans, Cells, Cultured, DEAD-box RNA Helicases, Enzyme Inhibitors, Eukaryotic Initiation Factor-4A, Female, Humans, Male, Models, Molecular, Molecular Conformation, DDX3, RNA, RNA Bind-n-Seq, dominant negative, eIF4A, ribosome, ribosome profiling, rocaglate, translation, translation inhibitor
Abstract

The translation inhibitor rocaglamide A (RocA) has shown promising antitumor activity because it uniquely clamps eukaryotic initiation factor (eIF) 4A onto polypurine RNA for selective translational repression. As eIF4A has been speculated to be a unique target of RocA, alternative targets have not been investigated. Here, we reveal that DDX3 is another molecular target of RocA. Proximity-specific fluorescence labeling of an O-nitrobenzoxadiazole-conjugated derivative revealed that RocA binds to DDX3. RocA clamps the DDX3 protein onto polypurine RNA in an ATP-independent manner. Analysis of a de novo-assembled transcriptome from the plant Aglaia, a natural source of RocA, uncovered the amino acid critical for RocA binding. Moreover, ribosome profiling showed that because of the dominant-negative effect of RocA, high expression of eIF4A and DDX3 strengthens translational repression in cancer cells. This study indicates that sequence-selective clamping of DDX3 and eIF4A, and subsequent dominant-negative translational repression by RocA determine its tumor toxicity.

Published
2021

13. The Translation Inhibitor Rocaglamide Targets a Bimolecular Cavity between eIF4A and Polypurine RNA

Author

Iwasaki, Shintaro, Iwasaki, Wakana, Takahashi, Mari, Sakamoto, Ayako, Watanabe, Chiduru, Shichino, Yuichi, Floor, Stephen N, Fujiwara, Koichi, Mito, Mari, Dodo, Kosuke, Sodeoka, Mikiko, Imataka, Hiroaki, Honma, Teruki, Fukuzawa, Kaori, Ito, Takuhiro, and Ingolia, Nicholas T

Subjects
Biochemistry and Cell Biology, Biological Sciences, Genetics, Adenylyl Imidodiphosphate, Aglaia, Amino Acid Substitution, Benzofurans, Binding Sites, Drug Resistance, Eukaryotic Initiation Factor-4A, HEK293 Cells, Humans, Models, Molecular, Molecular Structure, Mutation, Plant Proteins, Protein Binding, Protein Biosynthesis, Protein Interaction Domains and Motifs, Protein Synthesis Inhibitors, RNA, Ribosomes, Structure-Activity Relationship, FMO, Ribo-Seq, Rocaglamide, X-ray, crystal structure, eIF4A, evolution, ribosome profiling, sequence specificity, translation, Medical and Health Sciences, Developmental Biology, Biological sciences, Biomedical and clinical sciences, Health sciences
Abstract

A class of translation inhibitors, exemplified by the natural product rocaglamide A (RocA), isolated from Aglaia genus plants, exhibits antitumor activity by clamping eukaryotic translation initiation factor 4A (eIF4A) onto polypurine sequences in mRNAs. This unusual inhibitory mechanism raises the question of how the drug imposes sequence selectivity onto a general translation factor. Here, we determined the crystal structure of the human eIF4A1⋅ATP analog⋅RocA⋅polypurine RNA complex. RocA targets the "bi-molecular cavity" formed characteristically by eIF4A1 and a sharply bent pair of consecutive purines in the RNA. Natural amino acid substitutions found in Aglaia eIF4As changed the cavity shape, leading to RocA resistance. This study provides an example of an RNA-sequence-selective interfacial inhibitor fitting into the space shaped cooperatively by protein and RNA with specific sequences.

Published
2019

29. Direct observation of localized excitation in the lowest excited triplet state of fullerene dimers C120 and C120O by means of time-resolved electron paramagnetic resonance

Author

Yamauchi, Seigo, Funayama, Tomoyo, Ohba, Yasunori, Paul, Parimal, Reed, Christopher A, Fujiwara, Koichi, and Komatsu, Koichi

Subjects
Physical Sciences, Chemical Sciences, Technology, Chemical Physics
Abstract

Time-resolved EPR spectra were observed by means of the transient EPR technique for two kinds of fullerene dimers C120 and C120O in the lowest excited triplet (T1) states and compared with those of mono-adducts of fullerene (C60). It was found that zero-field splitting (zfs) parameters of both dimers are nearly the same as those of the monomers, indicating that the excitation is almost completely localized at one of the two fullerene units in the T1 state. © 2002 Elsevier Science B.V. All rights reserved.

Published
2002

30. Development of an epileptic seizure prediction algorithm using R–R intervals with self-attentive autoencoder

Author

10642514, Ode, Rikumo, Fujiwara, Koichi, Miyajima, Miho, Yamakawa, Toshikata, Kano, Manabu, Jin, Kazutaka, Nakasato, Nobukazu, Sawai, Yasuko, Hoshida, Toru, Iwasaki, Masaki, Murata, Yoshiko, Watanabe, Satsuki, Watanabe, Yutaka, Suzuki, Yoko, Inaji, Motoki, Kunii, Naoto, Oshino, Satoru, Khoo, Ming, Hui, Kishima, Haruhiko, Maehara, Taketoshi, 10642514, Ode, Rikumo, Fujiwara, Koichi, Miyajima, Miho, Yamakawa, Toshikata, Kano, Manabu, Jin, Kazutaka, Nakasato, Nobukazu, Sawai, Yasuko, Hoshida, Toru, Iwasaki, Masaki, Murata, Yoshiko, Watanabe, Satsuki, Watanabe, Yutaka, Suzuki, Yoko, Inaji, Motoki, Kunii, Naoto, Oshino, Satoru, Khoo, Ming, Hui, Kishima, Haruhiko, and Maehara, Taketoshi

Abstract

Epilepsy is a neurological disorder that may affect the autonomic nervous system (ANS) from 15 to 20 min before seizure onset, and disturbances of ANS affect R–R intervals (RRI) on an electrocardiogram (ECG). This study aims to develop a machine learning algorithm for predicting focal epileptic seizures by monitoring R–R interval (RRI) data in real time. The developed algorithm adopts a self-attentive autoencoder (SA-AE), which is a neural network for time-series data. The results of applying the developed seizure prediction algorithm to clinical data demonstrated that it functioned well in most patients; however, false positives (FPs) occurred in specific participants. In a future work, we will investigate the causes of FPs and optimize the developing seizure prediction algorithm to further improve performance using newly added clinical data.

Published
2023

31. Auditory Feedback of False Heart Rate for Video Game Experience Improvement

Author

10642514, 30263114, Ogawa, Sayaka, Fujiwara, Koichi, Kano, Manabu, 10642514, 30263114, Ogawa, Sayaka, Fujiwara, Koichi, and Kano, Manabu

Abstract

Changes in emotions affect our physiological responses, and perhaps vice versa. We investigate a new game interaction system that uses false heart rate (fHR) feedback to improve the player experience (PX). The fHR feedback presents false HR information to players so that they perceive changes in the presented HR as being a result of alteration in PX. We introduced auditory fHR feedback into game interaction and investigated its effects through an experiment. Participants repeated gameplay of an action game while hearing heartbeat-like sounds and answered questionnaires regarding PX. Some participants heard the heartbeat-like sounds synchronized with their actual HR, whereas others heard the heartbeat-like sounds whose tempo became gradually faster or slower than their actual HR. The results indicated that an accelerating fHR feedback pattern with +5 bpm/min was appropriate for improving PX; participants were able to maintain their motivation to continue the game. The experiment also indicated that it is necessary for participants to perceive the presented heartbeat-like sounds as reflecting their actual HR. Participants did not maintain their motivation when they were told that the presented sounds were not correlated with their actual HR. The present work provides new principles for video game interaction design based on physiological measurements.

Published
2023

34. Driver Drowsiness Detection Using R-R Interval of Electrocardiogram and Self-Attention Autoencoder

Author

Fujiwara, Koichi, Iwamoto, Hiroki, Hori, Kentaro, and Kano, Manabu

Abstract

Drowsy driving detection is crucial for avoiding serious traffic accidents. Changes in sleep conditions affect the autonomic nervous system (ANS) and, subsequently, heart rate variability (HRV), which is fluctuation in the R-R interval (RRI) in an electrocardiogram (ECG). HRV is easy to measure with a wearable sensor, and it may be possible to use HRV to detect drowsy driving. In conventional HRV-based drowsy driving detection methods, some HRV features are extracted from RRI data for analysis, but it may result in the loss of time-series characteristics of the RRI data. This study proposes a new driver drowsiness detection method that can detect abnormal changes in the RRI data caused by drowsiness. The proposed method employs a self-attention autoencoder (SA-AE), which is a type of neural network that can utilize time series characteristics. An experiment with a driving simulator was performed to evaluate the drowsiness detection performance of the proposed method. In this experiment, RRI data were collected from 20 participants (nonprofessional drivers) while driving, whose sleep conditions were scored by a sleep specialist based on electroencephalography (EEG) data. The experimental result showed that the proposed RRI-based drowsiness detection method detected 16 out of 18 sleep-related events while driving (sensitivity of 88%), and a false-positive rate of 0.60 times per hour was achieved. In addition, we validated the proposed method employing 18 middle-aged professional drivers. The proposed drowsiness detection method would contribute to preventing accidents caused by drowsy driving in the future.

Published
2024
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44. Development of an epileptic seizure prediction algorithm using R–R intervals with self-attentive autoencoder

Author

Ode, Rikumo, primary, Fujiwara, Koichi, additional, Miyajima, Miho, additional, Yamakawa, Toshikata, additional, Kano, Manabu, additional, Jin, Kazutaka, additional, Nakasato, Nobukazu, additional, Sawai, Yasuko, additional, Hoshida, Toru, additional, Iwasaki, Masaki, additional, Murata, Yoshiko, additional, Watanabe, Satsuki, additional, Watanabe, Yutaka, additional, Suzuki, Yoko, additional, Inaji, Motoki, additional, Kunii, Naoto, additional, Oshino, Satoru, additional, Khoo, Hui Ming, additional, Kishima, Haruhiko, additional, and Maehara, Taketoshi, additional

Published
2022
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50. Design and Synthesis of Cyclopropane Congeners of Resolvin E3, an Endogenous Pro-Resolving Lipid Mediator, as Its Stable Equivalents

Author

Arai, Shota, primary, Fujiwara, Koichi, additional, Kojima, Masahiro, additional, Aoki-Saito, Haruka, additional, Yatomi, Masakiyo, additional, Saito, Tsugumichi, additional, Koga, Yasuhiko, additional, Fukuda, Hayato, additional, Watanabe, Mizuki, additional, Matsunaga, Shigeki, additional, Hisada, Takeshi, additional, and Shuto, Satoshi, additional

Published
2022
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