Masashi Ikeda
Dokkyo University
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Amino Acids | 1997
T. Okayasu; Masashi Ikeda; Kazumi Akimoto; Kenji Sorimachi
SummaryHigh performance liquid chromatography was used to analyze the amino acid composition of cells. A total of 17 amino acids was analyzed. This method was used to compare the amino acid compositions of the following combinations: primary culture and established cells, normal and transformed cells, mammalian and bacterial cells, andEscherichia coli andStaphylococcus aureus. The amino acid compositions of mammalian cells were similar, but the amino acid compositions ofEscherichia coli andStaphylococcus aureus differed not only from mammalian cells, but also from each other. It was concluded that amino acid composition is almost independent of cell establishment and cell transformation, and that the amino acid compositions of mammalian and bacterial cells differ. Thus, it is likely that changes in amino acid composition due to cell transformation or species differences between mammalian cells are negligible compared with the differences between mammalian and bacterial cells, which are more distantly related.
European Journal of Pharmacology | 1998
Shu-ichi Kojima; Masashi Ikeda
The present study was designed to determine the influence of endogenous acetylcholine and nitric oxide (NO) on spontaneous luminal serotonin (5-hydroxytryptamine, 5-HT) release in the luminally perfused isolated guinea-pig proximal colon in vitro. 5-HT was determined by high-performance liquid chromatography with electro-chemical detection. The luminal outflow of 5-HT was significantly reduced by atropine (0.2 microM), hexamethonium (100 microM), the NO synthase inhibitor NG-nitro-L-arginine (L-NNA, 10 microM) and the NO-trapping agent 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO, 30 microM). Addition of excess L-arginine (300 microM) reversed the inhibitory effect of L-NNA on the 5-HT outflow. Physostigmine (1 microM) caused a great increase (atropine-sensitive) in 5-HT outflow. The enhancing action of physostigmine on 5-HT outflow was partially inhibited by L-NNA (100 microM) or carboxy-PTIO (30 microM), but was unaffected by the muscarinic M1 receptor antagonist pirenzepine (0.2 microM) or a muscarinic M3 receptor antagonist 4-diphenyl-acetoxy-N-methyl-piperidine methiodide (0.2 microM). These results suggest that 5-HT release from luminally perfused proximal colon of the guinea pig is stimulated via a NO pathway and cholinergic pathways which utilize muscarinic synapses and nicotinic synapses. Further, an intrinsic cholinergic-NO link appears to play a role in the stimulation of luminal 5-HT release, which may reflect the release of 5-HT from entero-chromaffin cells.
Journal of Chromatography B: Biomedical Sciences and Applications | 1993
Masashi Ikeda; Kenji Sorimachi; Kazumi Akimoto; Yosihiro Yasumura
A high-performance liquid chromatographic method for the analysis of hydroxyproline and proline has been developed. The method is based on the derivatization of the secondary amino group with dabsyl-chloride after blocking of the primary amino group with o-phthalaldehyde. Dabsyl-hydroxyproline and dabsyl-proline were separated from other amino acids by high-performance liquid chromatography in the gradient elution mode, and eluted at 10.27 and 16.02 min, respectively. The correlations between the peak areas of dabsyl-hydroxyproline and dabsyl-proline were linear in the range from 20-200 pmol, with equations y = 1.10x - 0.80 (r = 0.999) and y = 1.12x - 0.52 (r = 0.999), respectively. The method was applied to the analysis of rat tail collagen, and the contents of hydroxyproline and proline were 1.55 +/- 0.04 and 2.03 +/- 0.04 nmol/micrograms, respectively.
Amino Acids | 1991
Ryuichi Konno; Masashi Ikeda; Akira Niwa; Yosihiro Yasumura
SummaryUrine of mutant ddY/DAO− mice lackingd-amino-acid oxidase activity contained more serine and proline than that of normal ddY/DAO+ mice.d-Amino-acid oxidase treatment of urinary amino acids decreased the serine and proline, suggesting that they containedd-isomers. An HPLC analysis confirmed the presence ofd-serine. Urinary serine and proline contents were not decreased when the ddY/DAO− mice were fed a diet which did not contain supplementaryd-methionine or when they were given water containing antibiotics. These results suggest that thed-serine andd-proline do not derive from thed-methionine supplemented in the diet or from intestinal bacteria. In urine of the ddY/DAO− mice, a substance which seemed to bed-methionine sulfoxide and/ord-methionine sulfone was present. It is probably a metabolite of thed-methionine supplemented in the diet. Thed-aminoaciduria in the mutant mice lackingd-amino-acid oxidase activity indicates that this enzyme is involved in the metabolism of thed-amino acids in normal mice.
Amino Acids | 1995
Masashi Ikeda; Kenji Sorimachi; Kazumi Akimoto; Masami Okazaki; Masakatsu Sunagawa; Akira Niwa
SummaryIn order to analyse hydroxyproline (HYP) in urine, a high-performance liquid chromatographic method was modified. The primary amino groups were blocked with o-phthalaldehyde, and then the secondary amino groups were derivatized with 4-dimethylaminoazobenzene-4′-sulphonyl chloride. In addition, the dabsylated samples were treated with ethyl acetate to obtain a simple elution profile in high-performance liquid chromatography. The dabsyl-HYP and -proline were eluted at 4.7 min and 8.0 min, respectively. The chromatographic analysis was completed within 10 min, including the time needed for reequilibration of the column. Using the present method, the concentration of HYP in urine was determined to 260 ± 6µmol/l.
Journal of Pharmacological Sciences | 2005
Kazunobu Omura; Masahito Hitosugi; Xia Zhu; Masashi Ikeda; Hiroaki Maeda; Shogo Tokudome
Archives of Toxicology | 2000
Ryuichi Konno; Masashi Ikeda; K. Yamaguchi; Y. Ueda; Akira Niwa
Biochemical and Biophysical Research Communications | 2004
Tadatoshi Kinouchi; Shoichi Ishiura; Yoko Mabuchi; Yasuko Urakami-Manaka; Hideki Nishio; Yuji Nishiuchi; Masahiko Tsunemi; Katsumi Takada; Masatomo Watanabe; Masashi Ikeda; Hisao Matsui; Shigeo Tomioka; Hiroyuki Kawahara; Toshiro Hamamoto; Koichi Suzuki; Yasuo Kagawa
Journal of Pharmacological Sciences | 2005
Shu-ichi Kojima; Masashi Ikeda; Yuichiro Kamikawa
Bulletin of Environmental Contamination and Toxicology | 1991
Masatoshi Hayashi; Yasuie Shimazaki; Shin-ichi Kamata; Norihide Kakiichi; Masashi Ikeda