title: Spatial and temporal analysis of skin glycation by the use of multiphoton microscopy and spectroscopy.
abstract: BACKGROUND
  Tissue glycation, the main cause of many diabetes-related complications, results in the accumulation of advanced glycation endproducts (AGE).
  
  
  OBJECTIVE
  These AGEs are endogenous fluorophores that can serve as a viable pathological indicator for disease diagnostics. Here we explore the capabilities of multiphoton microscopy to non-invasively localize and quantify the skin glycation.
  
  
  METHODS
  In our study, multiphoton microscopy and spectroscopy were used to investigate glycation events-induced changes in the intensities of autofluorescence and second harmonic generation on ex vivo human skin.
  
  
  RESULTS
  Temporal and spatial dependence of degrees of glycation of the epidermis, collagen and elastin fibers of dermis were evaluated for their relevance to the changes in amplitudes of autofluorescence signals. We found that glycation drastically and linearly increases multiphoton autofluorescence intensity of epidermis and dermal collagen whereas changes in dermal elastin are moderate. We also found decrease in the level of second harmonic generation signal.
  
  
  CONCLUSIONS
  Our study suggests that due to intrinsically weak autofluorescence the dermal collagen is the most sensitive skin tissue to be used for detecting changes in tissue glycation.
authors.affiliation: Department of Physics, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Ara A
authors.initials: AA
authors.lastname: Ghazaryan
authors.forename: Po-Sheng
authors.initials: PS
authors.lastname: Hu
authors.forename: Shean-Jen
authors.initials: SJ
authors.lastname: Chen
authors.forename: Hsin-Yuan
authors.initials: HY
authors.lastname: Tan
authors.forename: Chen-Yuan
authors.initials: CY
authors.lastname: Dong
mesh_terms: D002102:Cadaver; D003094:Collagen / Q000378:metabolism; D004547:Elastic Tissue / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000378:metabolism*; D006801:Humans; D008297:Male; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D008875:Middle Aged; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D017127:Glycation End Products, Advanced; D003094:Collagen