The wavelengths and bandwidths of fluorescence spectra in normal mucosa, adenomatous polyps and malignant colonic tissue were determined and compared to that of type IV (basement membrane) collagen & elastin to evaluate their role in colonic fluorescence spectra. METHODS: Tissue was obtained at endoscopy (32 polyps, all tubular adenomas) & surgery (36 paired samples of normal mucosa and adenocarcinoma), which were immediately snap frozen in liquid Nitrogen and stored at -70 Celsius. Before spectroscopy, tissue was thawed over ice and moistened with phosphate buffered saline at pH 7.4 (PBS). A Spectrofluorometer with a Xenon lamp and excitation & emission spectrometers (Shimatzu RF-5301 PC, Columbia, MD) was used. Emission spectra (excitation: 290 nm to 400 nm, at 10 nm increments) were measured and digitally recorded (normalized intensity vs wavelength). Tissue was fixed and submitted for histology. Spectra from basement membrane (type IV) collagen & Elastin were similarly recorded. The wavelength of each emission peak and its full width at half maximum intensity (FWHM) were determined. RESULTS: Normal mucosa, adenomatous polyps and adenocarcinoma all gave 4 emission peaks (W-Z), without any significant difference in wavelength or bandwidth. Their mean wavelength in nm ± standard error, with FWHM in parenthesis were: W) 331.3 ± 0.7, (53.4); X) 365.1 ± 1.0 (9.5); Y) 385.7 ± 2.0 (40.4); Z) 453.1 ± 6.0 (100.5). Collagen type IV gave 4 emission maxima; at the following wavelengths with FWHM in brackets: 345 (64), 365 (12), 392 (28) and 430 (125). Elastin produced peaks at 365 nm (FWHM 20) and 390 nm (FWHM 103). All values in nanometers. PBS had negligible fluorescence. CONCLUSIONS: Four major emission peaks were identified in all three tissue groups. Their wavelengths and bandwidths were independent of histology and tissue geometry. Type IV (basement membrane) collagen is probably responsible for peak X and may be the cause of peak Y. Elastin does not contribute to tissue fluorescence in the range measured.
|Original language||English (US)|
|State||Published - Dec 1 1998|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging