Search

Copyright of International Journal of Cosmetic Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The topical treatment of nail fungal infections has been a focal point of nail research in the past few decades as it offers a much safer and focused alternative to conventional oral therapy. Although the current focus remains on exploring the ways of enhancing permeation through the formidable nail barrier, the understanding of the nail microstructure and composition is far from complete. This article reviews our current understanding of the nail microstructure, composition and diseases. A few of the parameters affecting the nail permeability and potential causes of the recurrence of fungal nail infection are also discussed. [ABSTRACT FROM AUTHOR]

Background/purpose: The water content of skin has a significant impact on skin properties; sufficient hydration is necessary to keep the skin supple, flexible, and smooth. To understand more completely the water retention properties of the human skin barrier, physical macroscopic properties must be related to the structural organization of the stratum corneum (SC). Water, lipids, and natural moisturizing factor (NMF) influence the molecular structures that affect the properties of SC, including water sorption and binding enthalpy. In the research reported here, isothermal microcalorimetry was used to study the interaction of water vapor with isolated human SC in intact, delipidized, and water-washed delipidized forms to identify the influences of the principal components of SC on water sorption. The calorimetric data are interpreted in conjunction with spectroscopic results to identify the conformational changes in keratins induced by lipid and NMF removal and to assess the influence of these changes on water binding in SC. Methods: Isothermal calorimetry was used to measure the integral heat of water vapor sorption on intact, delipidized, and water-washed delipidized human SC at 32 °C as a function of relative humidity using back and thigh skin from three donors. Calorimetric measurements were combined with water vapor sorption measurements to determine the differential thermodynamic properties of these systems. Attenuated total reflection–Fourier transform infrared spectroscopy was used to investigate effects of extraction on protein secondary structure. Results: The magnitudes of the differential enthalpy, entropy, and free energy were greatest for intact SC and least for water-washed delipidized SC. Water sorption followed a similar trend. Delipidization led to a significantly reduced binding enthalpy at low water content; water washing the delipidized SC had only a small additional effect on binding enthalpy. Delipidization converts a fraction of keratin α-helixes to turns and random coils, while water sorption converts a fraction of keratin α-helixes to β-sheets, turns, and random coils. Conclusions: The results of this study are consistent with a water sorption model in which keratin–keratin hydrogen bonds are replaced by keratin–water hydrogen bonds. Delipidization reduces the fraction of dry keratin that is in the α-helix conformation, suggesting that lipids hold the keratins in a conformation conducive to optimal hydration. [ABSTRACT FROM AUTHOR]

Background/purpose: The current method of producing cultured skin substitutes (CSS) is focused on providing treatments for severe skin wounds/burns. We have developed a modified growth method to make them more suitable for in vitro product-testing/toxicity-testing purposes. Method: CSS grown in Petri dishes were either transferred to Franz diffusion cells on day 5 (modified method) or left in the Petri dish (standard method) and maintained in these environments for the remainder of the growth phase. Mitochondrial metabolism (MTT assay) was measured on days 5, 10 and 14 and histology was studied on days 5, 10 and 14. Barrier function for all tissues was evaluated by transferring them to Franz cells (standard method) and measuring transepidermal water loss (TEWL), 3H2O penetration and 14C-niacinamide permeability on days 7, 14 and 21. Results: CSS grown by the standard and modified methods showed comparable cell viability and tissue morphology. Barrier function, however, was markedly improved in CSS grown by the modified method. The average improvement at days 7 and 14 was 1.3-fold for TEWL, 2.1-fold for 3H2O penetration and 6.4-fold for 14C-niacinamide permeability. The barrier function of CSS grown by the modified method was still significantly lower than that of human cadaver skin tested by the same methods. Conclusions: CSS developed using the anchored multi-cell system showed similar cell viability and morphology and improved barrier function compared with CSS produced by the standard Petri dish method, thereby improving its potential as an in vitro skin permeability and toxicity model. [ABSTRACT FROM AUTHOR]

The physical and transport properties of keratinized tissues are closely related to their water content. This report presents water uptake and desorption isotherms for the human nail and compares them with those of wool, horn, hair, and stratum corneum. Nail absorbed a maximum of ~0.3 gH2O/g dry tissue, with the shape and magnitude of the isotherm most closely resembling horn. Hysteresis between uptake and desorption was observed, similar to that of other keratins. The shape of the isotherms was adequately described by both the D’Arcy-Watt and Guggenheim-Anderson-deBoer (GAB) models; however, small positive deviations from both models were found in the relative humidity range, 30–60%. Directionally better fits to the data were found with the D’Arcy-Watt model. This analysis suggests that most of the water in the tissue was in a strongly bound state, consistent with observations made by other techniques. [ABSTRACT FROM AUTHOR]