TY - JOUR
T1 - Spectroscopic measurements of photoinduced processes in human skin after topical application of the hexyl ester of 5-aminolevulinic acid
AU - Zhao, Lu
AU - Nielsen, Kristian P.
AU - Juzeniene, Asta
AU - Juzenas, Petras
AU - Lani, Vladimir
AU - Ma, Li Wei
AU - Stamnes, Knut
AU - Stamnes, Jakob J.
AU - Moan, Johan
PY - 2006
Y1 - 2006
N2 - Although 5-aminolevulinic acid, ALA, and its derivatives, have been widely studied and applied in clinical photodynamic therapy (PDT), there is still a lack of reliable and non-invasive methods and technologies to evaluate physiological parameters of relevance for the therapy, such as erythema, melanogenesis, and oxygen level. We have investigated the kinetics of these parameters in human skin in vivo during and after PDT with the hexyl ester of ALA, ALA-Hex. Furthermore, the depth of photosensitizer (protoporphyrin IX, PpIX) production after different application times was investigated. It was found that the depth increased with increasing application time of ALA-Hex. We also investigated the depth of PpIX before and after light exposure causing 50% photobleaching at 407 nm. The PpIX localized in superficial layers of the normal tissue was removed during the bleaching. Thus, after bleaching, the remaining PpIX was localized mainly in the deeper! layers of normal tissue. We have applied fluorescence emission spectroscopy, fluorescence excitation spectroscopy, and reflectance spectroscopy in the study of the above-mentioned parameters. In conclusion, fluorescence excitation spectroscopy and reflectance spectroscopy are simple, useful, reliable, and noninvasive techniques in the evaluation of the processes taking place in human skin in vivo during and after PDT. Using these methods we were able to quantify melanogenesis, O2 level, erythema, vasoconstriction, and vasodilatation.
AB - Although 5-aminolevulinic acid, ALA, and its derivatives, have been widely studied and applied in clinical photodynamic therapy (PDT), there is still a lack of reliable and non-invasive methods and technologies to evaluate physiological parameters of relevance for the therapy, such as erythema, melanogenesis, and oxygen level. We have investigated the kinetics of these parameters in human skin in vivo during and after PDT with the hexyl ester of ALA, ALA-Hex. Furthermore, the depth of photosensitizer (protoporphyrin IX, PpIX) production after different application times was investigated. It was found that the depth increased with increasing application time of ALA-Hex. We also investigated the depth of PpIX before and after light exposure causing 50% photobleaching at 407 nm. The PpIX localized in superficial layers of the normal tissue was removed during the bleaching. Thus, after bleaching, the remaining PpIX was localized mainly in the deeper! layers of normal tissue. We have applied fluorescence emission spectroscopy, fluorescence excitation spectroscopy, and reflectance spectroscopy in the study of the above-mentioned parameters. In conclusion, fluorescence excitation spectroscopy and reflectance spectroscopy are simple, useful, reliable, and noninvasive techniques in the evaluation of the processes taking place in human skin in vivo during and after PDT. Using these methods we were able to quantify melanogenesis, O2 level, erythema, vasoconstriction, and vasodilatation.
KW - ALA-Hex PDT
KW - Erythema
KW - Fluorescence excitation spectroscopy
KW - Melanogenesis
KW - Oxygen
KW - Reflectance spectroscopy
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U2 - 10.1615/JEnvironPatholToxicolOncol.v25.i1-2.200
DO - 10.1615/JEnvironPatholToxicolOncol.v25.i1-2.200
M3 - Article
C2 - 16566726
AN - SCOPUS:33644778934
SN - 0731-8898
VL - 25
SP - 307
EP - 320
JO - Journal of Environmental Pathology, Toxicology and Oncology
JF - Journal of Environmental Pathology, Toxicology and Oncology
IS - 1-2
ER -