Details of a Researcher - KOBAYASHI Nobumichi

Isolation and characterisation of poliovirus mutants resistant to heating at 50 degrees C for 30 min

H Shiomi, T Urasawa, S Urasawa, N Kobayashi, S Abe, K Taniguchi

JOURNAL OF MEDICAL VIROLOGY ( WILEY-LISS ) 74 ( 3 ) 484 - 491 2004.11

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Poliovirus is heat-labile; on heating at 50degreesC for 30 min its infectivity decreases drastically and its antigenicity reverts from N to H. However, mutants resistant to heating at 50degreesC for 30 min from the Sabin 1 and 2 viruses were isolated by repeating the process of incubation of the virus stock at 50degreesC for 30 min and multiplication of the remaining virus in a cell culture. The isolated mutants were stable genetically, and maintained the rct and d markers of the parent virus. On electron microscopical examination, the mutants were observed to retain the intact morphology after being heated at 50degreesC for 30 min, while the parent virus was converted to empty particles devoid of RNA under the same conditions. On determination of the nucleotide sequence of the P1 region, a single nucleotide sequence substitution was detected at nucleotide no. 2741, resulting in an amino acid change from valine to alanine at the 87th position of VP1. This amino acid might be associated with the heat-resistance of the mutants. Furthermore, it was found that the thermostable mutants obtained in this study, which are resistant to "high" temperature (50degreesC) for a short time (30 min), were not stable against heating at the ambient temperature (37degreesC) for a long time (5 or 7 days). This suggests that the inactivation at high temperature for a short time and that at ambient temperature for a long time involve different mechanisms. (C) 2004 Wiley-Liss, Inc.

DOI
Prediction analysis for measles epidemics

A Sumi, N Ohtomo, Y Tanaka, S Sawamura, LF Olsen, N Kobayashi

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS ( INST PURE APPLIED PHYSICS ) 42 ( 12 ) 7611 - 7620 2003.12

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A newly devised procedure of prediction analysis, which is a linearized version of the nonlinear least squares method combined with the maximum entropy spectral analysis method, was proposed. This method was applied to time series data of measles case notification in several communities in the UK, USA and Denmark. The dominant spectral lines observed in each power spectral density (PSD) can be safely assigned as,fundamental periods. The optimum least squares fitting (LSF) curve calculated using these fundamental periods can essentially reproduce the underlying variation of the measles data. An extension of the LSF curve can be used to predict measles case notification quantitatively. Some discussions including a predictability of chaotic time series are presented.

DOI CiNii
Human group B rotavirus infections cause severe diarrhea in children and adults in Bangladesh

T Sanekata, MU Ahmed, A Kader, K Taniguchi, N Kobayashi

JOURNAL OF CLINICAL MICROBIOLOGY ( AMER SOC MICROBIOLOGY ) 41 ( 5 ) 2187 - 2190 2003.05

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Human group B rotavirus was detected in 12 of 220 adult patients and 2 of 67 child patients with severe diarrhea in Bangladesh. Group B rotavirus may be virulent in both adults and children, and the virus may be an especially serious diarrheal agent in Bangladesh.

DOI
Molecular characterization and epidemiology of group B rotaviruses.

Diarrhoeal diseases - current status, research trends and field studies 2003
感染症のダイナミクス

札幌医学雑誌 72 23 - 29 2003