Chiharu Ishii

Chiral amino acid analysis, especially the determination of trace levels of D-enantiomers, is currently gathering attention in a variety of research areas including the food/clinical sciences. These D-amino acids had long been believed to be absent in the higher animals. However, by the advances of analytical technologies, some of the D-enantiomers are found in mammals including humans and increasingly recognized as novel physiologically-active substances and/or biomarkers. For the determination

Intestinal microbiota and their metabolites are strongly associated with host physiology. Developments in DNA sequencing and mass spectrometry technologies have allowed us to obtain additional data that enhance our understanding of the interactions among microbiota, metabolites, and the host. However, the strategies used to analyze these datasets are not yet well developed. Here, we describe an original analytical strategy, metabologenomics, consisting of an integrated analysis of mass spectrome

In this paper, we consider the omni-directional vision using equidistance projection fish eye lens. The partial domain of an original image in fish eye image is selected, and this is converted to a perspective image for human eyes based on a projection rule of fish eye lens so that it may become the same as a standard image which is obtained by central projection of common lens. However, since this conversion enlarges the original image spatially and is based on discrete data, crevice is generat

Chiral amino acids in fermented products including Japanese traditional black vinegar, a processed cheese and nam pla were determined using an on-line two-dimensional (2D) HPLC-MS/MS system. As the target amino acids, Ala, Asp, Glu, Leu, Pro and Ser were selected. Prior to the HPLC separation, the fermented products were appropriately homogenized and deproteinized, then amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). Using the 2D-HPLC system, the target NBD-amino

For the discovery of sensitive biomarkers of kidney function focusing on chiral amino acids, a multiple heart-cutting two-dimensional (2D) liquid chromatography-mass spectrometry (LC-MS)/MS system has been designed/developed. As the target analytes, alanine (Ala), aspartic acid, glutamic acid (Glu), leucine (Leu), lysine, methionine, phenylalanine (Phe), proline (Pro), serine (Ser), and valine were selected considering the presence of their d-forms in mammals. The 2D LC-MS/MS system consisted of

The formation of D-amino acid residues in proteins is considered as one of the deterioration processes, and the determination of these D-amino acid residues is highly expected for the screening of new biomarkers under various disease conditions. In the present study, a two-dimensional (2D) HPLC-MS/MS system following the hydrolysis with deuterium chloride (2HCl/2H2O) and derivatization of amino acids with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) has been designed/developed and applied to th

Due to the recent discoveries of several D-amino acids in mammals and also by the elucidation of their physiological functions and/or availabilities as diagnostic markers, the enantioselective analysis of intrinsic amino acids has been the focus of attention. Based on the determination of amino acids with chiral discrimination, the clarification of their distributions, regulation mechanisms, physiological functions and the diagnostic/therapeutic values of a wide variety of D-amino acids is expec

A B6DAO-/- mouse strain lacking D-amino acid oxidase (DAO) activity with the genetic background of C57BL strain, frequently used to produce disease model mice in the current medical/life science areas, was newly developed. In the plasma of the control C57BL/6J and mutant B6DAO-/- mice, five D-amino acids widely found in mammals were determined using a highly-selective two-dimensional LC-MS/MS system. As the targets, D-alanine (Ala), D-aspartic acid (Asp), D-leucine (Leu), D-proline (Pro) and D-s

A highly-selective three-dimensional (3D) HPLC system has been designed/developed for the determination of acidic amino acid enantiomers, i.e., aspartic acid (Asp) and glutamic acid (Glu). The 3D-HPLC system consisted of a reversed-phase column (Singularity RP18, 1.0 ×250 mm) in the first dimension, a mixed-mode column (Singularity MX-001, 1.5 ×250 mm) in the second dimension and a Pirkle-type enantioselective column (Singularity CSP-011S, 1.5 ×250 mm) in the third dimension. By using this syste