title: Determination of chronological aging parameters in epidermal keratinocytes by in vivo harmonic generation microscopy.
abstract: Skin aging is an important issue in geriatric and cosmetic dermatology. To quantitatively analyze changes in keratinocytes related to intrinsic aging, we exploited a 1230 nm-based in vivo harmonic generation microscopy, combining second- and third-harmonic generation modalities. 52 individuals (21 men and 31 women, age range 19-79) were examined on the sun-protected volar forearm. Through quantitative analysis by the standard algorithm provided, we found that the cellular and nuclear size of basal keratinocytes, but not that of granular cells, was significantly increased with advancing age. The cellular and nuclear areas, which have an increase of 0.51 μm(2) and 0.15 μm(2) per year, respectively, can serve as scoring indices for intrinsic skin aging.
authors.affiliation: Department of Dermatology, National Taiwan University Hospital and College of Medicine, National Taiwan University, No.7, Chung-Shan South Road, Taipei 10002,  Taiwan ; Molecular Imaging Center, National Taiwan University, No.1, Sec.4, Roosevelt Road, Taipei 10617,  Taiwan ; yihualiao@ntu.edu.tw.
authors.forename: Yi-Hua
authors.initials: YH
authors.lastname: Liao
authors.forename: Szu-Yu
authors.initials: SY
authors.lastname: Chen
authors.forename: Sin-Yo
authors.initials: SY
authors.lastname: Chou
authors.forename: Pei-Hsun
authors.initials: PH
authors.lastname: Wang
authors.forename: Ming-Rung
authors.initials: MR
authors.lastname: Tsai
authors.forename: Chi-Kuang
authors.initials: CK
authors.lastname: Sun
keywords: (110.0180) Microscopy; (170.1530) Cell analysis; (170.1610) Clinical applications; (170.1870) Dermatology; (170.3880) Medical and biological imaging; (190.4160) Multiharmonic generation