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Incontinence-associated dermatitis (IAD) is a painful yet preventable form of cumulative skin irritation prevalent amongst those with limited movement. Consequently, it has a significant impact on the quality of life for those affected as well as substantial cost implications. Prevention and intervention is typically through good skin hygiene regimes and regular use of barrier products. In this paper, we describe the development of an in vivo model of IAD in healthy volunteers by occluded application of alkaline synthetic urine to the volar aspect of volunteer's forearms for 6 h per day over a five-day period to reproduce the moist and irritant conditions causative of IAD. Irritation was assessed and quantified on a daily basis by a series of non-invasive biophysical measurements and compared to a contralateral saline-treated (control) site. Dermal irritation was assessed by subjective (visual) and objective measurements (laser Doppler and polarisation spectroscopic imaging, infrared thermography, skin reflectance spectroscopy, transepidermal water loss and skin surface pH). The provocation of reproducible, cumulative skin irritation was successfully demonstrated and quantified. This five-day model of irritation is considered appropriate for the initial clinical assessment of topical products to prevent or treat IAD. [ABSTRACT FROM AUTHOR]

The skin of neonates and infants exhibits distinct anatomical and functional properties that might be clinically reflected by its characteristic susceptibility to skin barrier disruption. In this systematic review, we aimed to characterize skin barrier maturation as reflected by transepidermal water loss (TEWL) and skin surface pH during the first 2 years of life. We systematically searched MEDLINE and EMBASE via OVID from 1975 to 2013 to identify primary studies reporting TEWL and/or skin surface pH values in healthy full-term infants aged 0-24 months without any cutaneous diseases. After full text assessment, 36 studies reporting n = 8,483 TEWL measurements for 26 anatomical areas and n = 6,437 skin surface pH measurements for 14 anatomical areas were included. The mean age of the subjects ranged from 1.4 h to 1.2 years. The lowest pH of 4.63 was identified on the forehead at the age of 25.6 weeks, whereas the highest of 7.31 was on the volar forearm at 0.0 weeks. The lowest TEWL value of 3.1 g/m/h was reported for the back at 0.6 weeks and the highest of 43.1 g/m/h for the upper leg at 58.7 weeks. The skin surface pH reveals a steep decline during the first postnatal week, succeeded by a further gradual site-specific acidification process during the first month. A competent permeability barrier in most anatomical areas is indicated by TEWL, which does not exhibit a time-dependent development during the first 2 years of life. [ABSTRACT FROM AUTHOR]

The objective of this study was to clarify variations of the ceramide (CER) profile in human stratum corneum (SC) in different seasons and in different regions of the body and to estimate the contributions of CERs to the SC barrier and water-holding functions. Based on the information that there are great variations of SC functions among body sites, we compared the CER profiles obtained from ten different anatomical sites in healthy Japanese males in four seasons. Not only the physiological parameters of skin but also the CER profile showed body region and seasonal variations. The total CER level, the CER composition and the C34-CER[NS] species displayed strong correlations with the values of transepidermal water loss and capacitance throughout the body. Especially in the cheek, a strong correlation between the capacitance and the CER profile was observed. There were seasonal variations of the CER profile in the lip, upper arm and palm. Our results indicate that regional and seasonal variations of the CER profile may contribute to SC functions. [ABSTRACT FROM AUTHOR]

Patients with a prosthetic limb report negative skin effects, including irritation, rash and chaffing, which can lead to infection, discomfort and reduced wear time to significantly impact normal activities. The aims were to examine the epidermal integrity (transepidermal water loss, TEWL), stratum corneum (SC) hydration [moisture accumulation rate (MAT)], friction and biomechanical properties in active below the knee amputees and to determine the effects of an inert sock liner on skin condition. The liner reduced hydration, TEWL and friction and increased elasticity versus the amputee's conventional skin care methods. Residual limb TEWL was increased and MAT was reduced versus the contralateral normal skin. In a second study, we hypothesized that complete occlusion would decrease free amino acids (FAA) and quantified them by high performance liquid chromatography in an adult volar forearm model. Occlusion with a water vapor impermeable wet dressing led to increased TEWL, erythema and dryness and reduced MAT versus normal skin, comparable to the results in the amputees. The FAA levels were significantly reduced for the occluded sites. The results suggest that residual limb occlusion in amputees may block the formation of FAA in the upper SC. Therapies based on replacement of water binding FAAs, may alleviate the consequences of long-term occlusion. [ABSTRACT FROM AUTHOR]

Ethanol intake is associated with a variety of skin diseases. The aim of the present study was (1) to identify the pathways of release of orally administered ethanol through the skin, and (2) to investigate the effects of a single oral dose of ethanol on the penetration of topically applied substances into the skin. Ethanol evaporation via the skin was measured using the new technique of ion mobility spectrometry (IMS). Transepidermal water loss (TEWL) and skin surface temperature were simultaneously measured before and after ethanol consumption. Measurements were performed on skin sites with different stratum corneum (SC) thickness, and density of follicles and sweat glands. These appendages were selectively sealed to investigate their participation in ethanol evaporation. The penetration of a topically applied UV filter substance was studied before and after ethanol consumption after removing the SC with adhesive tape. Ethanol evaporation was measured within 5 min of consumption, while the skin surface temperature remained nearly constant. The sealing of the appendages did not have a significant effect on ethanol evaporation. On the forehead, a higher TEWL value was measured than on the forearm. On both skin sites, an increase in TEWL was observed after ethanol ingestion. No influence of orally administered ethanol on the penetration of the topically applied UV filter substance was observed. The results indicate that ethanol evaporation occurs via the lipid layers without a significant effect on the penetration of the topically applied substance. [ABSTRACT FROM AUTHOR]

The stratum corneum, which is the outermost layer of the skin, functions as an important barrier to maintain biological homeostasis. The multilamellar structures formed by intercellular lipids present in the stratum corneum are considered to play an important role in barrier function. Most intercellular lipids are unbound and can be extracted by organic solvents, but some intercellular lipids are covalently bound to cornified envelope proteins. Decreases in unbound lipid levels reduce the barrier function of the stratum corneum, but the relationship between bound lipid and the barrier function of the stratum corneum is not well understood. In this study, we examined the relationship between the amount of covalently bound ceramide, the main bound lipid, and the barrier function of the stratum corneum. A single dose of UVB irradiation (2 × MED), or continuous UVB irradiation (0.5 × MED/day for 14 days) to the back, or feeding with an essential fatty acid-deficient (EFAD) diet for ¶8 weeks caused a significant elevation of TEWL and a significant reduction in covalently bound ceramides in hairless rats. Transmission electron microscopy revealed that the intercellular multilamellar structures in the stratum corneum of treated rats were incomplete (folding, defects, unclear images) compared to the structures seen in the stratum corneum of non-UVB-irradiated and non-EFAD rats. These results suggest that the amount of covalently bound ceramides is highly correlated with the barrier function of the skin, and that covalently bound ceramides play an important role in the formation of lamellar structures, and are involved in the maintenance of the barrier function of the skin. [ABSTRACT FROM AUTHOR]

Moisturizers are used in the treatment of dry skin, both clinically and in cosmetic products. In the present study the influence of different moisturizers on the normal skin barrier properties was evaluated by measuring transepidermal water loss (TEWL) and skin capacitance. In addition, the skin reactivity to a topically applied surfactant, sodium lauryl sulphate (SLS), following the use of the moisturizers was examined. The skin reaction was assessed visually and by measuring TEWL and superficial blood flow. Treatment with two urea-containing moisturizers for 10 and 20 days decreased TEWL. The irritant reactions after exposure to SLS were also significantly decreased after prior treatment for 20 days with the urea-containing moisturizers. In a double-blind vehicle-controlled part of the study, urea was found to decrease the skin susceptibility to SLS after only three applications. However, this decrease in skin reactivity was not preceded by a reduction in TEWL. Skin capacitance increased after three applications of urea-containing moisturizers and was still increased after 10 days, but not after 20 days of this treatment. Treatment for 20 days with two moisturizers without urea did not influence either TEWL or the susceptibility to irritation from SLS, but it increased the skin capacitance significantly. The mechanism underlying these changes is not known. The lower degree of SLS-induced irritation in the skin treated previously with urea-containing moisturizers may be of clinical relevance in reducing contact dermatitis from irritant stimuli. [ABSTRACT FROM AUTHOR]