title: Precise analysis of the autofluorescence characteristics of rat colon under UVA and violet light excitation.
abstract: OBJECTIVE
  Tissue autofluorescence study is a promising means of endoscopic detection of colonic neoplasia, but the mechanism of autofluorescence eruption has still not been verified. The purpose of this study was to precisely analyze the autofluorescence characteristics of freshly prepared normal rat colon under UVA and violet light excitation.
  
  
  METHODS
  Excised rat colons were studied by using multichannel spectrophotometry, spectroscopic imaging, confocal microscopy, combined two-photon excited fluorescence and second-harmonic generation (SHG) microscopy, and fluorescence lifetime imaging microscopy.
  
  
  RESULTS
  Spectroscopic analysis of freshly prepared colon sections revealed that the mucosa and the submucosa showed strong autofluorescence under UVA and violet light excitation. The combined images of two-photon and SHG microscopy revealed that the mucosal epithelia are the important source of autofluorescence. Nicotinamide adenine dinucleotide seems to be one of the major substances involved in the autofluorescence of the mucosal layer on 365- nm light excitation. The autofluorescence spectra of the luminal surfaces were identical to those of the mucosa on crosssectional examinations with 365-nm excitation. The main origin of autofluorescence of the luminal surface with 365-nm excitation is the epithelial cells in the mucosa without overlay of submucosal fluorescence.
  
  
  CONCLUSIONS
  The mucosal layer is the important source of the autofluorescence observed under excitation with UVA/violet light in multilayered colonic structures. Illumination of 365-nm wavelength light is a suitable means of analyzing the autofluorescence of mucosal epithelia.
authors.affiliation: Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto 602-8566, Japan.
authors.forename: Keimei
authors.initials: K
authors.lastname: Nakano
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Harada
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamaoka
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Miyawaki
authors.forename: Katsuichi
authors.initials: K
authors.lastname: Imaizumi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takaoka
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakaoka
authors.forename: Naoki
authors.initials: N
authors.lastname: Wakabayashi
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Takamatsu
mesh_terms: D000818:Animals; D003106:Colon / Q000033:anatomy & histology*; D005453:Fluorescence; D007413:Intestinal Mucosa / Q000033:anatomy & histology*; D008027:Light; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D009243:NAD; D051381:Rats; D011916:Rats, Inbred F344; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D009243:NAD