Blue light induces DNA damage in normal human skin keratinocytes.

Background: The generation of DNA damage by ultra-violet radiations (UV) is well established, and both the nature of the DNA lesions and their respective DNA repair pathways have largely been described. Besides UV rays, visible light constitutes a very important part of the sun spectrum where blue light is considered a significant contributor to premature aging. However, blue light-induced DNA damage has not been deeply explored yet.

The social integration of healthcare agency workers in long-term care facilities: A cross-sectional study.

Background: Patient care quality is a key concern for long-term care facilities and is directly related to effective collaboration between healthcare professionals. The use of agency staff in long-term care facilities creates important challenges in terms of coordination and communication within work units.

Objectives: The purpose of this study is to assess the mediating effect of common in-group identity in the relationship between permanent employees' perceptions regarding the use of agency workers -namely distributive justice, perceptions of threat, perceived similarities with agency workers, and leader inclusiveness toward agency staff- and the permanent employees' adoption of collaborative behaviours.

Laser Scanning Microscopic Investigations of the Decontamination of Soot Nanoparticles from the Skin.

Background/aims: Airborne pollutants, such as nano-sized soot particles, are increasingly being released into the environment as a result of growing population densities and industrialization. They can absorb organic and metal compounds with potential biological activity, such as polycyclic aromatic hydrocarbons and airborne pollen allergens. Local and systemic toxicities may be induced in the skin if the particulates release their harmful components upon dermal contact.

Influence of Topical, Systemic and Combined Application of Antioxidants on the Barrier Properties of the Human Skin.

Background: The formation of free radicals in human skin by solar ultraviolet radiation is considered to be the main reason for extrinsic skin aging. The antioxidants in human tissue represent an efficient protection system against the destructive action of these reactive free radicals. In this study, the parameters of the skin, epidermal thickness, stratum corneum moisture, elasticity and wrinkle volume, were determined before and after the treatment with antioxidant- or placebo-containing tablets and creams.

Free Radical Threshold Value: A New Universal Body Constant.

Three evolutionary sources create 'primary' reactive oxygen species (ROS) and 'secondary' lipid oxygen species (LOS), forming the human body's 'free radical ground state'. We present evidence for the existence of a universal free radical threshold value (FRTV), defining the borderline between advantageous and adverse effects of free radicals observed above the free radical ground state. Based on standard vitamin D doses, the calculated amount of ∼3.

Low to moderate doses of infrared A irradiation impair extracellular matrix homeostasis of the skin and contribute to skin photodamage.

Human skin is daily exposed to sun rays, which include not only ultraviolet radiation, but also an important quantity of infrared (IR) radiation. In the past few years, many publications have underlined the negative impact of IR radiation on the human skin, particularly when the skin and/or the cells are exposed to high sun irradiance and significant doses of IR. In the present study, we demonstrate, in vitro on normal human fibroblasts, that even under low irradiance with single or very few repeated doses, infrared A irradiation (IRA) produces free radicals, triggers major changes in the expression of the type I collagen and elastin network, impairs the dermal-epidermal junction, upregulates several matrix metalloproteinases and has an impact on the expression of key genes of the extracellular matrix.

Influence of sun exposure on the cutaneous collagen/elastin fibers and carotenoids: negative effects can be reduced by application of sunscreen.

Resonance Raman spectroscopy and multi-photon tomography were used in vivo to analyse the influence of sun exposure on the cutaneous carotenoids and collagen/elastin fibers. Comparing Berlin (low sun exposure) and Monegasque (high sun exposure) volunteers, it could be demonstrated that extended sun exposure significantly reduces the cutaneous carotenoids and collagen/elastin concentration (p < 0.05).

Transfer of ultraviolet photon energy into fluorescent light in the visible path represents a new and efficient protection mechanism of sunscreens.

The development of sunscreens with high sun protection factor (SPF) values but low filter concentrations is the ultimate goal. The purpose of the present study was to investigate why a sunscreen spray and cream with different concentrations of the same UV-filters provided the same SPF. Therefore, the homogeneity of the distribution of both sunscreens was investigated by laser scanning microscopy (LSM) and tape stripping (TS).

Dermal carotenoid level and kinetics after topical and systemic administration of antioxidants: enrichment strategies in a controlled in vivo study.

Background: High doses of sun-emitted UV-radiation induce reactive oxygen species (ROS) as major pro-oxidants thus inducing premature skin aging. The best prevention of the destructive action of free radicals in human skin is textile coverings, topical sunscreens and the development of a high antioxidative protective network.

Objective: The effects of topical, systemic and combined application of antioxidants (AO) were investigated on human skin in vivo.

How a calculated model of sunscreen film geometry can explain in vitro and in vivo SPF variation.

Spectroscopic in vitro assay has recently gained importance for UVA protection, or even for SPF assessment, as manufacturers are increasingly keen to replace in vivo by in vitro tests. These assays are based on transmission UV spectroscopy of a known amount of sunscreen product spread onto an ultraviolet-transparent substrate. In the most recent European publications or methods, the preferred substrate is a roughened PMMA plate.

A catch-up validation study on reconstructed human epidermis (SkinEthic RHE) for full replacement of the Draize skin irritation test.

Efforts to fully replace the in vivo Draize skin irritation test, according to the Directive 67/548/ECC or OECD TG 404, were reinforced with the seventh Amendment of the Cosmetic Directive and the REACh regulation. In 2007, the EpiSkin test method was scientifically validated and recognized as the stand alone method to discriminate skin irritants (R38) from non-irritants (no label) according to the definition of the EU risk phrases. An ECVAM performance standards (PS) document was defined to evaluate the accuracy and reliability of other analogous test methods (ECVAM SIVS, May 2007).

Evaluation of photolyase (Photosome) repair activity in human keratinocytes after a single dose of ultraviolet B irradiation using the comet assay.

Photosome is constituted of photolyases included in liposomes. Photolyase is a bacterial enzyme that can repair ultraviolet B (UVB)-induced cyclobutane pyrimidine dimers (CPD) in eukaryotic cells. A modified version of the alkaline comet assay has been set up to evaluate the repair activity of this enzyme after a single dose of UVB (312 nm, 0.