title: Fiberoptic resonance Raman spectroscopy to measure carotenoid oxidative breakdown in live tissues.
abstract: Based on compelling epidemiologic and corroboratory in vitro studies, carotenoids are thought to have great potential as dietary prevention against cancer. Yet, carotenoid-based chemopreventive trials have found very contradictory results. Definitive conclusions from these trials are hampered by an inability to accurately and safely measure carotenoids in specific tissues at risk of cancer development. Raman spectroscopy has been proposed as an optical technology with which to analyze various molecules in live tissues. One major obstacle that impedes the clinical use of this powerful technology is the lack of a fiberoptic Raman probe suitable for endoscopic tissue evaluation. A single-fiber resonance Raman Spectroscope capable of noninvasive "optical biopsies" to measure carotenoid concentrations in live tissues has been developed. The accuracy of this Raman instrument was confirmed by comparison with more standard methods of spectrophotometry and high-pressure liquid chromatography using solubilized beta-carotene (BC) and BC-loaded cells before use in a small patient cohort. This Raman instrument detected intact BC as well as BC oxidative breakdown as a decrement of its Raman signal in cells. Use of the Raman instrument in our small cohort study showed its feasibility for measuring human tissues and raised some potentially intriguing possibilities about BC tissue pharmacokinetics and oxidative biology. Based on these results, our newly developed single fiberoptic resonance Raman instrument may provide a very useful method of measuring carotenoids and their oxidative breakdown within live tissue during future carotenoid chemopreventive trials. This proof-of-concept study provides the foundation to justify future validation of our Raman prototype.
authors.affiliation: Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Utah School of Medicine, 50 North Medical Drive, Salt Lake City, UT 84132, USA. brandon.bentz@hci.utah.edu
authors.forename: Brandon G
authors.initials: BG
authors.lastname: Bentz
authors.forename: Jason
authors.initials: J
authors.lastname: Diaz
authors.forename: Terry A
authors.initials: TA
authors.lastname: Ring
authors.forename: Mark
authors.initials: M
authors.lastname: Wade
authors.forename: Konrad
authors.initials: K
authors.lastname: Kennington
authors.forename: David M
authors.initials: DM
authors.lastname: Burnett
authors.forename: Robert
authors.initials: R
authors.lastname: McClane
authors.forename: Frank A
authors.initials: FA
authors.lastname: Fitzpatrick
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002338:Carotenoids / Q000032:analysis* / Q000378:metabolism; D015331:Cohort Studies; D004724:Endoscopy / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D005336:Fiber Optic Technology / Q000295:instrumentation / Q000379:methods*; D049669:History, 16th Century; D006801:Humans; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D013059:Spectrum Analysis, Raman / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult
chemical_list: D002338:Carotenoids