The stratum corneum (SC) plays a fundamental role in the barrier function of the skin. The SC consists of corneocytes embedded in a lipid matrix. The main lipid classes in the lipid matrix are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The aim of this study was to examine the effect of the chain length of FFAs on the thermotropic phase behavior and mixing properties of SC lipids. Fourier transform infrared spectroscopy and Raman imaging spectroscopy were used to study the mixing properties using either protonated or deuterated FFAs. We selected SC model lipid mixtures containing only a single CER, CHOL and either a single FFA or a mixture of FFAs mimicking the FFA SC composition. The single CER consists of a sphingoid base with 18 carbon atoms and an acyl chain with a chain length of 24 carbon atoms. When using lignoceric acid (24 carbon atoms) or a mixture of FFAs, the CER and FFAs participated in mixed crystals, but hydration of the mixtures induced a slight phase separation between CER and FFA. The mixed crystalline structures did not phase separate during storage even up to a time period of 3months. When using palmitic acid (16 carbon atoms), a slight phase separation was observed between FFA and CER. This phase separation was clearly enhanced during hydration and storage. In conclusion, the thermotropic phase behavior and the mixing properties of the SC lipid mixtures were shown to strongly depend on the chain length and chain length distribution of FFAs, while hydration enhanced the phase separation.
The aim of this work was to develop a nanolayered pH sensitive coating method whereby proteins are coated at a suitable pH on the surface of chemically modified biomedical/bioanalytical microdevices and protein release is triggered by a pH-shift upon contact with the physiological environment. In this work such a coating was developed and was applied onto microneedles. First, the surface of microneedle arrays was modified with basic groups with a surface pK a below physiological pH. This modification was a multistep procedure: first the surface was hydroxylated in a piranha mixture, then 3-aminopropyltriethoxysilane was coupled (yielding a "pH independent" surface with a positive charge over a broad pH range), next 4-pyridinecarboxaldehyde was coupled to the obtained surface amine groups and finally the imine bond was reduced by sodium cyanoborohydride. The obtained pH-sensitive pyridinemodified microneedles were coated with ovalbumin at surface pK a > pH > pI of the protein; thus the surface of the microneedles is positively charged and the protein is negatively charged. The coating efficiency of ovalbumin was 95% for the amine-modified (pH independent) and the pyridine-modified (pH sensitive) surfaces, whereas a non-modified surface had a coating efficiency of only 2%. After the protein-coated microneedle arrays were pierced into the skin, having a pH > surface pK a of the microneedle arrays, 70% of the protein was released within 1 minute, whereas the protein release from pH independent microneedle arrays was only 5%. In conclusion, we developed a procedure to efficiently coat microneedle arrays with proteins that are released upon piercing into human skin.
Background: Skin occlusion caused by the use of diapers or sanitary napkins often results in irritant contact dermatitis. Furthermore, prolonged occlusion and exposure to body fluids are known to increase skin hydration and permeability, thus leading to irritant contact dermatitis.Objective: To investigate the effects of water exposure on the skin and its barrier functions, in order to obtain more insights into the mechanisms of irritant contact dermatitis.Methods: Water patches were applied to the volar forearm skin of 10 human subjects for 3 hours. Permeability of the stratum corneum (SC) was examined with methyl nicotinate (MN).Alterations in the hydration and ultrastructure of the SC were measured with Raman spectroscopy and multiphoton microscopy, respectively.Results: Water profiles found with Raman spectroscopy showed notable increases in water content throughout the SC and skin surface. Multiphoton microscopy showed morphological changes in the intercellular space of the SC. Emerged pools seemed to contribute to increased MN absorption.Conclusion: Excessive skin hydration leading to changes in the SC ultrastructure might result in increased skin permeability to skin irritants and allergens.
and MMP-9 activities from its lowest concentration, and MMP-1 and MMP-2 at its higher concentrations, which implies a greater protective effect on elastin. It dramatically increased the expression of types I, III, and V collagens, and elastin, fibrillin-1, and fibrillin-2 in dermal fibroblasts. The effects were similar to those of ascorbic acid. This is the first report identifying xanthohumol's potential to improve skin structure and firmness: it simultaneously inhibits the activities of elastase/MMPs and stimulates the biosynthesis of fibrillar collagens, elastin, and fibrillins.pp. 133-145 Comparison of hydration, tyrosinase resistance, and antioxidant activation in three kinds of pearl powders by
incorporation into an o/w emulsion at 8% yielded increased viscosity and reduced emulsion droplet size as compared to the emollient ester CCT (capric/caprylic triglyceride) or a control formulation. Quantitative data indicate that application of the o/w emulsion formulation containing either HP or CCT significantly elevated skin moisture content and thus reduced transepidermal water loss (TEWL) by a maximal 33% against the control formulation within 3 h and maintained this up to 6 h. Visual observation of skin treated with the HP-containing formulation showed fine texture and clear contrast as compared to the control or the CCT formulation, confirming this effect. As a result of increased hydration, skin conductivity, as measured in terms of corneometer values, was also elevated significantly by about tenfold as early as 20 min after HP or CCT application and was maintained throughout the test period. Throughout the test period the HP formulation was 5-10% more effective than the CCT formulation both in reduction of TEWL as well as in increased skin conductivity. Thus, compared to the emollient ester (CCT), HP showed a unique capability for long-lasting effect in retaining moisture and improving skin texture.J. Cosmet. Sci., 60, 25-29 (January/February 2009) A rapid method to clinically assess the effect of an anti-acne formulation Synopsis Historically, clinical evaluation of acne treatment has been based on direct visual assessment and the counting of lesions over a period of several weeks of treatment. However, with advancing technology there has been ever-increasing speed in the effectiveness of these treatments. To successfully assess these faster treatments, acne pathology needs to be evaluated in a shorter time frame. The object of these studies was to develop techniques to evaluate individual acne lesions in a shorter time frame and to assess speedier treatment technologies. Ten healthy volunteers with acne lesions on their upper backs were recruited for the study. Two inflamed acne lesions were selected for each treatment, along with lesions to be left untreated, on each volunteer. Each lesion was marked, photographed, and visually graded. A skin surface microscope (Scopeman) was used to visualize size and to grade the lesions by two experts every day for five days. The sites were treated once a day for the course of the study. There was a remarkable reduction in the size and erythema of acne lesions after treatment with the acne formulation as compared to the untreated and vehicle-treated lesions. Individual lesions, both treated and untreated, appeared resolved in 14 days. This resolution can be noticeably accelerated by topical treatments. We have developed a simple and faster clinical method to evaluate the effects of topical anti-acne technology.A technology for the deposition of a persistent hydrophobicity to alkaline-color-treated weathered hair surfaces using 18-MEA (18-methyleicosanoic acid) is presented. Two approaches were examined in order to make 18-MEA bind tightly to the alkaline-color-tre...
There are several in vitro methods to determine the whitening potential of actives; however, the in vivo testing of skin whiteners is a long and expensive process. We have designed a rapid clinical method to screen potential skin whiteners using a UV-induced skin tan as a model. Small areas of identical suntan are repeatably induced on the skin, and treatment of these sites allows rapid screening of several skin whiteners within the course of a month. The method provides reproducible results and valuable information about the potential skin-lightening activity of topical preparations.
Additional Supporting Information may be found in the online version of this article:Data S1. Methods. Table S1. Association between IL13, IL4, IL5 variants and different patient groups. The effects of Sox21 gene deletion on hair lipids have been studied. For the cuticle-specific bound lipid 18-methyl eicosanoic acid (18-MEA), which was found to predominantly exist as the free form in Sox21 À/À hair, total levels and distribution were unexpectedly unchanged. This indicates that while the biosynthesis of 18-MEA is unaffected, its covalent attachment to the cuticle surface is disrupted by loss of keratinassociated protein binding partners. Although the class compositions differed, the total ceramide (CER) levels were found to be comparable between Sox21 +/+ and Sox21 À/À hairs. Deletion of the gene was also found to increase cholesterol sulphate (CS) levels. The biosynthesis process might be associated with cuticle keratinocyte maturation, because both CS and CERs are known bioactives in keratinocyte differentiation.
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