title: Effect of intense pulsed-light exposure on lipid peroxides and thymine dimers in human skin in vivo.
abstract: BACKGROUND
  Intense pulsed light (IPL) generates high-intensity short flashes of visible light and has been used for about 10 years to improve dermatological conditions such as telangiectasia, pigmented lesions, and skin aging. Although these systems deliver a moderate dose (10-30 J/cm(2)) of visible light, this dose is delivered during a short pulse (2-5 milliseconds), which implies a very high fluence rate (approximately 4000 W/cm(2)). For this reason, we speculated whether the Bunsen-Roscoe law of reciprocity could still be valid in these conditions.
  
  
  METHODS
  Nine healthy volunteers were exposed to IPL or UV-A or simulated solar UV radiation, and then thymine dimer and lipid peroxide concentrations were determined in skin biopsy specimens of the exposed sites. Only exposure to solar UV radiation (7-J/cm(2) UV-A + 80-mJ/cm(2) UV-B) produced measurable amounts of thymine dimers in DNA from skin biopsy specimens, whereas UV-A radiation (40 J/cm(2)) and IPL (9 J/cm(2)) induced 3-fold and 6-fold increases of cutaneous lipid peroxides, respectively.
  
  
  CONCLUSIONS
  These preliminary results indicate that IPL, although filtered for wavelengths shorter than 500 nm, can generate oxidative stress, a typical hallmark of UV-A, but does not induce thymine dimers. This emphasizes the need for long-term studies involving IPL before using this technique in a recurrent manner.
authors: Author Affiliations: Dermatology Department, University Hospital of Geneva, Geneva, Switzerland.
authors: Olivier
authors: O
authors: Sorg
authors: Victor
authors: V
authors: Janer
authors: Christophe
authors: C
authors: Antille
authors: Pierre
authors: P
authors: Carraux
authors: Evelyne
authors: E
authors: Leemans
authors: Elizabeth
authors: E
authors: Masgrau
authors: Jean-Hilaire
authors: JH
authors: Saurat
authors: Denis
authors: D
authors: Salomon
mesh_terms: D000293:Adolescent; D000328:Adult; D006801:Humans; D008054:Lipid Peroxides / Q000032:analysis / Q000528:radiation effects*; D008875:Middle Aged; D011740:Pyrimidine Dimers / Q000032:analysis / Q000528:radiation effects*; D012867:Skin / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D008054:Lipid Peroxides; D011740:Pyrimidine Dimers