Are you Ken-ichi Hisamatsu?

Claim your profile

Publications (3)4.48 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Our purpose was to investigate mucosal cell injury due to the nitric oxide (NO)-superoxide system in otitis media with effusion. We determined the levels of nitrotyrosine (NT) and NO and the activities of superoxide dismutase (SOD) and lactic dehydrogenase (LDH) in 90 middle ear fluid samples. The NT concentration was significantly higher in group A (<16 years old) than in group C (>50 years old; p < .05), and significantly higher in the acute group than in the chronic group (p < .05). The NO concentration did not show a significant difference among the groups. The activity of SOD showed significant correlations with the concentrations of NT and NO and with LDH activity (p < .05). The LDH activity was significantly greater in group A than in group C (p < .05). Our results indicate involvement of the NO-superoxide system in the pathogenesis of otitis media with effusion, showing evidence of protein and/or cell injury in the middle ear.
    The Annals of otology, rhinology, and laryngology 10/2005; 114(10):804-8. · 1.21 Impact Factor
  • Otolaryngology-head and Neck Surgery - OTOLARYNGOL HEAD NECK SURG. 01/2003; 129(2).
  • [Show abstract] [Hide abstract]
    ABSTRACT: A gas mediator, nitric oxide is converted to peroxynitrite in the presence of superoxide anion. Peroxynitrite is a potent oxidant, which injures various tissues and organs by nitration of the tyrosine residues of proteins, and it enhances the late response of inflammation. The determination of nitrated tyrosine, nitrotyrosine, which is a stable final metabolite of peroxynitrite, provides an important indicator of tissue disorders caused by peroxynitrite. This paper reports a competitive solid-phase immunoassay for measuring nitrotyrosine in various biological specimens. In this study, peroxidase-conjugated nitrotyrosine was prepared by reaction of nitrotyrosine with 1,4-benzoquinone treatment, and then it was allowed to compete with nitrotyrosine on an anti-nitrotyrosine antibody-coated 96-well multiplate. No amino acids or related compounds tested in the experiments interfered with the immune reaction of nitrotyrosine, except cysteine, which only slightly inhibited the immune reaction at the concentrations higher than 1000 times the concentration of nitrotyrosine. The limit of detection of free nitrotyrosine was approximately 500 pg/mL (2 nM) at a competition ratio (B/B(o)%) of 80%. The newly developed enzyme immunoassay (EIA) method was used for assay of nitrotyrosine in biological specimens, with the following results: (i) Lipopolysaccharide (LPS) activation of RAW264.7 cells induced a significant increase in nitrotyrosine production compared to that with nonactivated cells. N(omega)-nitro-L-arginine methyl ester decreased nitrotyrosine production with either LPS-activated or nonactivated RAW cells. There is a relationship between nitrotyrosine production and nitrite ion. (ii) The nitrotyrosine level detected in the plasma specimens from healthy volunteers was 35.21 +/- 4.87 ng/mL (135.4 +/- 18.7 nM). (iii) The concentration of nitrotyrosine in the nasal lavage fluid of allergic rhinitis patients was 41.40 +/- 20.96 ng/mL (159.02 +/- 80.6 nM). Thus, the EIA method combines sensitivity and specificity with the ability to process a large number of specimens to quantify nitrotyrosine produced with in vivo and in vitro sources.
    Nitric Oxide 09/2002; 7(1):11-7. · 3.27 Impact Factor