Biological effects of simulated ultraviolet daylight: a new approach to investigate daily photoprotection.

Background: The irradiance of standard ultraviolet daylight (UV-DL) is representative of most frequently encountered UV exposure conditions and simulators of UV-DL can now be used to properly investigate the biological effects of a non-extreme UV radiation. One of the characteristics of the simulated UV-DL used in this study is its dUVA to dUVB irradiance ratio, which amounts to 24, instead of close to 10, for the simulated zenithal UV radiation (UV-SSR).

Purpose/methods: The aim of our study was to compare photobiological effects induced, in human skin, by acute and semi-chronic exposure to simulated UV-DL with those induced by UV-SSR.

Histological evaluation of a topically applied retinol-vitamin C combination.

Two double-blind studies versus vehicle were carried out to investigate the effects of a topically applied retinol plus vitamin C combination on epidermal and dermal compartments of aged or photoaged human skin. The two studies were performed on postmenopausal women who were selected for treatment based on the mild level of elastosis of their facial skin. At completion of treatment, skin biopsies were collected and processed for classical histology and immunohistochemistry.

Modulation of gene expression induced in human epidermis by environmental stress in vivo.

Environmental insults on the skin induce biologic responses through the modulation of expression of genes implicated in different cell functions. The aim of this study was to investigate the modulation of gene expression profile in human epidermis in vivo following different stresses. We determined the modulations of gene expression using cDNA macroarray in the epidermis of 28 healthy volunteers, following mild and physiologic insults, including: (1), tape stripping; (2) application of 10% sodium dodecyl sulfate; (3) daily application of vaseline; and (4), exposure to one minimal erythema dose of solar-simulated radiation.

High ultraviolet A protection affords greater immune protection confirming that ultraviolet A contributes to photoimmunosuppression in humans.

Solar radiation causes immunosuppression that contributes to skin cancer growth. Photoprotective strategies initially focused on the more erythemogenic ultraviolet B. More recently, the relationship of ultraviolet A and skin cancer has received increased attention.

p53 mutations in cutaneous lesions induced in the hairless mouse by a solar ultraviolet light simulator.

We investigated skin lesions induced in hairless SKH:HR1 mice by chronic exposure to a solar ultraviolet light (UV) simulator for alterations of the p53 gene in conserved domains. Mutations of exons 5-8 of the p53 gene in skin lesions were screened in 31 benign skin lesions (hyperplasias), 25 precancerous skin lesions (keratoacanthomas), and 25 malignant skin lesions (squamous cell carcinomas; SCC) by polymerase chain reaction-single-strand conformation polymorphism analysis. Most of the mutations occurred at dipyrimidine sequences located on the nontranscribed strand; the most frequent modifications were C-->T transitions (77%) and CC-->TT tandem mutations (5%); the latter are considered the UV fingerprint.