The Damaging Effects of Long UVA (UVA1) Rays: A Major Challenge to Preserve Skin Health and Integrity.

Within solar ultraviolet (UV) light, the longest UVA1 wavelengths, with significant and relatively constant levels all year round and large penetration properties, produce effects in all cutaneous layers. Their effects, mediated by numerous endogenous chromophores, primarily involve the generation of reactive oxygen species (ROS). The resulting oxidative stress is the major mode of action of UVA1, responsible for lipid peroxidation, protein carbonylation, DNA lesions and subsequent intracellular signaling cascades.

Metabolism of DHEA in postmenopausal women following percutaneous administration.

The marked decline in serum dehydroepiandrosterone (DHEA) with age is believed to play a role in health problems associated with aging, these health issues being potentially preventable or reversible by the exogenous administration of DHEA. In the present study, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) and gas chromatrography/mass spectrometry (GC/MS) were used to measure the serum levels of DHEA and 11 of its metabolites in seventy-five 60-65-year-old Caucasian women who received 3g of 0.1%, 0.

Androgen glucuronides, instead of testosterone, as the new markers of androgenic activity in women.

Despite the long series of cohort studies performed during the last 20 years, the correlation between serum testosterone and any clinical situation believed to be under androgen control in women has remained elusive. This is likely related to the recent finding that the androgens made locally in large amounts in peripheral tissues from the precursor dehydroepiandrosterone (DHEA) act in the same cells where synthesis takes place and are not released in significant amounts in the circulation, thus making unreliable the measurement of serum testosterone as marker of total androgenic activity. The objective is to determine if serum androgen glucuronides can be replaced by testosterone or another steroid as measure of androgenic activity.

Long-term expansion of human functional epidermal precursor cells: promotion of extensive amplification by low TGF-beta1 concentrations.

We have previously introduced the concept of high proliferative potential-quiescent (HPP-Q) cells to refer to primitive human hematopoietic progenitors, on which transforming growth factor-beta1 (TGF-beta1) exerts a pleiotropic effect. TGF-beta1 confers to these slow-dividing cells a mitogenic receptor(low) phenotype and maintains immature properties by preventing differentiation and apoptosis. However, the effect of TGF-beta1 on long-term expansion has not yet been clearly demonstrated.

Peroxisome proliferator-activated receptor-alpha enhances lipid metabolism in a skin equivalent model.

Peroxisome proliferator-activated receptors are involved in certain cell types such as adipocytes and hepatocytes, in the control of several pathways of lipid synthesis or catabolism by regulating the gene expression level of key lipid metabolizing enzymes. As the epidermis exhibits an extensive lipid metabolism necessary for the establishment of the barrier function, we have examined the role of peroxisome proliferator-activated receptor-alpha activation in this process. Living skin equivalents were treated with Wy 14,643, a selective peroxisome proliferator- activated receptor-alpha ligand, which enhanced greatly the synthesis of membrane coating granules, the organelles specialized in the processing of stratum corneum lipids.