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629 results on '"Okamura, Kunihiro"'

12. The SRA protein Np95 mediates epigenetic inheritance by recruiting Dnmt1 to methylated DNA

Author

Sharif, Jafar, Muto, Masahiro, Takebayashi, Shin-ichiro, Suetake, Isao, Iwamatsu, Akihiro, Endo, Takaho A., Shinga, Jun, Mizutani-Koseki, Yoko, Toyoda, Tetsuro, Okamura, Kunihiro, Tajima, Shoji, Mitsuya, Kohzoh, Okano, Masaki, and Koseki, Haruhiko

Abstract

DNA methyltransferase (cytosine-5) 1 (Dnmt1) is the principal enzyme responsible for maintenance of CpG methylation and is essential for the regulation of gene expression, silencing of parasitic DNA elements, genomic [...]

Published
2007

13. A novel extraction method of fetal electrocardiogram from the composite abdominal signal

Author

Sato, Michiyoshi, Kimura, Yoshitaka, Chida, Shinichi, Ito, Takuya, Katayama, Norihiro, Okamura, Kunihiro, and Nakao, Mitsuyuki

Subjects
Abdomen -- Research, Electrocardiogram -- Research, Electrocardiography -- Research, Fetal heart -- Research, Biological sciences, Business, Computers, Health care industry
Abstract

In contrast to the ultrasonic measurement of fetal heart motion, the fetal electrocardiogram (ECG) provides clinically significant information concerning the electrophysiological state of a fetus. In this paper, a novel method for extracting the fetal ECG from abdominal composite signals is proposed. This method consists of the cancellation of the mother's ECG and blind source separation with the reference signal (BSSR). The cancellation of the mother's ECG component was performed by subtracting the linear combination of mutually orthogonal projections of the heart vector. The BSSR is a fixed-point algorithm, the Lagrange function of which includes the higher order cross-correlation between the extracted signal and the reference signal as the cost term rather than a constraint. This realizes the convexity of the Lagrange function in a simple form, which guarantees the convergence of the algorithm. By practical application, the proposed method has been shown to be able to extract the P and T waves in addition to the R wave. The reliability and accuracy of the proposed method was confirmed by comparing the extracted signals with the directly recorded ECG at the second stage of labor. The gestational age-dependency of the physiological parameters of the extracted fetal ECG also coincided well with that of the magnetocardiogram, which proves the clinical applicability of the proposed method. Index Terms--Blind source separation with reference signal, fetal electrocardiogram, P and T waves.

Published
2007

17. Association of maternal smoking during pregnancy and infant neurobehavioral status

Author

Suzuki, Keita, Nakai, Kunihiko, Oka, Tomoko, Sakai, Takeo, Hosokawa, Toru, Okamura, Kunihiro, Satoh, Chieko, and Satoh, Hiroshi

Subjects
Smoking and women -- Psychological aspects, Smoking in pregnancy -- Psychological aspects, Smoking in pregnancy -- Analysis, Psychology and mental health
Abstract

The association of maternal smoking during pregnancy with neurobehavioral status was examined in 344 Japanese infants. Based on a questionnaire, their mothers were classified into three groups, Nonsmokers, Exsmokers, and Smokers. The Neonatal Behavioral Assessment Scale was administered three days after birth. Among the three groups, on the seven clusters and their 28 behavioral subscales there were no significant differences. The infants of Smokers had lower scores than those of Exsmokers and Nonsmokers on two behavioral items, general tone and peak of excitement. General tone remained significant after adjustment for covariates.

Published
2006

21. International Advisory Board

Author

Wahed, Ahmad M. Abdel, primary, Dekker, Gustaaf, additional, Duan, Tao, additional, Jeganathan, J. Ravichandran R., additional, Lau, Tze Kin, additional, Lee, Keun-Young, additional, Okamura, Kunihiro, additional, Okonofua, Friday E., additional, Pattinson, Robert C., additional, Vadeyar, Shantala, additional, and Villar, Jose, additional

Published
2011
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22. Fractal and periodic heart rate dynamics in fetal sheep: comparison of conventional and new measures based on fractal analysis

Author

Koshino, Takahiro, Kimura, Yoshitaka, Kameyama, Yoshinobu, Takahashi, Takeshi, Yasui, Tomoharu, Chisaka, Hiroshi, Sugawara, Junichi, and Okamura, Kunihiro

Subjects
Circadian rhythms -- Physiological aspects, Heart beat -- Measurement, Biological sciences
Abstract

The physiological significance of spectral and fractal components of spontaneous heart rate (HR) variability in the fetus remains unclear. To examine the relationship between circadian rhythms in different measures of HR variability, R-R interval time series obtained by fetal ECGs were recorded continuously over 24 h in five pregnant sheep at 116-125 days gestation. Conventional measures of short-term (STV) and long-term variability (LTV), low-frequency (LF; 0.025-0.15 cycles/beat) and high-frequency (HF; 0.2-0.5 cycles/beat) spectral powers, the LF-to-HF ratio, and fractal dimension values were calculated from 24-h ECG recordings and quantified every 60 min. STV, LTV, and LF and HF spectral powers were minimal during the day but increased significantly to their highest values at night. We found a significant positive correlation between these measures, whereas the cosinor method showed significant similarity between their circadian rhythm patterns. Fetal R-R intervals also exhibited fractal structures. Fetal HR variability had a fractal structure, which was similar between day and night. These results suggested that the circadian rhythms exhibited by STV and LTV during the day were mainly due to changes in frequency components rather than to fractal components of fetal HR fluctuation. circadian rhythm; fetal heart rate variability

Published
2003

37. Time-frequency analysis of fetal heartbeat fluctuation using wavelet transform

Author

Kimura, Yoshitaka, Okamura, Kunihiro, Watanabe, Takanori, Yaegashi, Nobuo, Uehara, Shigeki, and Yajima, Akira

Subjects
Heart beat -- Analysis, Cardiology -- Research, Fetus -- Research, Nervous system, Autonomic -- Research, Biological sciences
Abstract

A study was conducted to analyze the influence of the nonlinear control mechanism of the fetal autonomic nervous system on different fetal states. A nonlinear structure of the time series of heart rate fluctuation of the gamma distribution in heart fetuses was considered. Results indicated that the existence of the gamma distribution structure from 17 weeks of gestation onward. It proved that the gestation stage is an important property of the circulation control mechanism of a living body.

Published
1998

44. Fetal signals and parturition

Author

Challis, John R. G., Bloomfield, Frank H., Bocking, Alan D., Casciani, Valentina, Chisaka, Hiroshi, Connor, Kristin, Dong, Xuesen, Gluckman, Peter, Harding, Jane E., Johnstone, Jim, Li, Wei, Lye, Stephen, Okamura, Kunihiro, and Premyslova, Marina

Published
2005

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