Shinya Yamaguchi

Evaluation of chemiluminescence reagents for selective detection of reactive oxygen species

In order to evaluate the chemiluminescence (CL) reagents for selective detection of reactive oxygen species (ROS), we comprehensively measured the CL responses of 20 CL reagents (three luminol derivatives, two imidazopyrazinone derivatives, eight lophine derivatives, six acridinium ester derivatives and lucigenin) against six types of ROS (superoxide anion: O(2)(*-), hydroxyl radical: *OH, hydrogen peroxide: H(2)O(2), hypochlorite anion: ClO(-), singlet oxygen: (1)O(2), and nitric oxide: NO). As a result of the screening, it was found that nine CL reagents selectively detected O(2)(*-) while one CL reagent selectively detected *OH. However, no CL reagent had selectivity on the detection of H(2)O(2), ClO(-), (1)O(2) and NO. Our screening results could help to select the most suitable CL reagent for selective determination of different ROS. As an application study, 4-methoxyphenyl-10-methylacridinium-9-carboxylate (MMAC), one of the acridinium ester derivatives, showed high selectivity on the detection of O(2)(*-), and thus was applied to the assay of superoxide dismutase (SOD) activity. The dynamic range and detection limit of the developed CL assay were 0.1-10 and 0.06 U mL(-1), respectively. Significant correlation (r=0.997) was observed between the results by the CL assay using MMAC and the spectrophotometric assay using 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt.

Signet ring cell early gastric cancer presenting as an elevated lesion.

SummaryEarly gastric cancer composed of signet ring cell carcinoma is usually present as a depressed lesion and rarely manifests as a protruding lesion. To our knowledge, only eight cases have been reported in the literature. We herein report such a rare lesion which developed in an asymptomatic 55-year-old man.