Water Content In Human Skin Research Articles

Conformal sensor-based harmonic wave technique for in-vivo non-invasive monitoring skin water content

The thermal conductivity of human skin reflects the water content of skin, and thus is a strong indicator of skin health status. The current diagnosis methods for human skin can only detect the water content in a small depth beneath the skin surface, typically within the stratum corneum layer (10–20 μm), which fails to extract the water content in larger depth such as dermis, thereby limiting the timely diagnosis of some severe skin diseases (psoriasis, dry skin, skin eczema, etc.). Here we developed a conformal sensor-based harmonic wave technique which can modulate the thermal wave penetration depth and thus measure the water content in both epidermis and dermis. Variations in water content for three factors (age, site and BMI index) of different subjects were discussed. The progress made so far provides a useful approach for monitoring the water content of human skin and early warning of skin diseases.

Anatomical site variation of water content in human skin measured by the Epsilon: A pilot study.

BackgroundThis pilot study aimed to investigate the anatomical site variation of water content of the stratum corneum (SC) on the body by measuring skin capacitance with the Epsilon, a new generation corneometer with multiple sensors. Secondly, values of the Epsilon were compared to values measured by conventional single sensor corneometers.MethodsThe hydration status of SC was measured in 15 healthy Caucasian volunteers with the Epsilon at five body sites (cheek, lower forearm, mid‐calf, lower back and abdomen). Transepidermal water loss (TEWL) was measured with the Aquaflux to get more insight into the condition of the skin barrier. A literature search was performed to compare Epsilon values with conventional corneometers.ResultsThe tested anatomical locations showed significant differences in water content (P < 0.001) with large interindividual variations; highest values were found in the cheek (11.64ε) and lowest values in the mid‐calf (4.43ε). No correlation between water content and TEWL was found. In general, Epsilon values were lower compared to values of conventional corneometers, with a similar trend.ConclusionThis pilot study showed significant variations in water content at different skin locations measured by the Epsilon. Moreover, the Epsilon measured consistent lower values compared to single sensor corneometers. Further validation of the device is recommended.

The Potential of the Double Debye Parameters to Discriminate Between Basal Cell Carcinoma and Normal Skin

The potential of terahertz imaging for improving the efficiency of Mohs's micrographic surgery in terms of tumor margin detection was previously studied. Thanks to high water content of human skin, its dielectric response to terahertz radiation can be described by the double Debye model which uses five parameters to fit experimental data. Skin tumors typically have a higher water content than normal tissues do, and this should be apparent in the parameters. The goal of this paper is to apply statistical methods to these parameters to test their power to differentiate skin cancer from normal tissue. Based on the prediction accuracy estimated using a cross-validation method, we found the best classifier was the static permittivity at low frequency $({\mmb\varepsilon}_{s})$ . By combining the most relevant parameters, we obtained a classification accuracy of 95.7%, confirming the classification capability of the parameters, thereby supporting their application to improve terahertz imaging for the purpose of skin cancer delineation.

The effect of external mechanical compression on in vivo water content in human skin

We have studied the influence of external mechanical compression on diffuse reflection spectra of human skin tissue under in vivo conditions in the spectral range 800–2000 nm. It has been found that the external compression leads to a decrease in the reflection coefficient of the skin. Analysis of spectra based on the diffusion approximation of the radiation transfer theory has allowed us to find that the external compression weakens both absorbing and scattering properties of the skin. We have revealed that, of the two processes that control the in vivo reflection coefficient of skin in the near-infrared spectral range under conditions of its external mechanical compression, the weakening process of the scattering properties of tissue as a result of the displacement of water out of the volume of the skin subjected to the compression is predominating. It has been found that, under the application of an external compression of 110 kPa, the water content in the skin decreases by a value of about 10%. The stabilization process of diffuse reflection spectra under external compression conditions has an inertial character. In this case, under the application of an external compression of 110 kPa, the stabilization time of spectra is about 10 min, whereas, after the removal of the compression, the skin recovers its optical properties in the near-IR range within the period of time of about 50 min.

Intrinsic aging- and photoaging-dependent level changes of glycosaminoglycans and their correlation with water content in human skin

Glycosaminoglycans (GAGs) have various structural and physiological regulatory functions in skin, including tissue water maintenance, due to their high water-holding capacity. To investigate changes of GAGs during intrinsic aging and photoaging of human skin and their correlations with water content. Samples of sun-protected buttock and sun-exposed forearm skin were obtained from young male (21-30 years, n=8) and female (20-33 years, n=8) subjects, as well as old male (70-78 years, n=8) and female (70-80 years, n=8) subjects, and their epidermal and dermal contents of hyaluronic acid (HA), total sulfated GAG (tsGAG), total uronic acid (tUA), and tissue water were measured. HA content was determined by enzyme-linked immunosorbent assay using HA-binding protein, tsGAG by the sulfated GAG assay kit using 1,9-dimethylmethylene blue, tUA by carbazole reaction, and tissue water by subtraction of tissue dry weight from wet weight. In the buttock, HA was higher in dermis than in epidermis, while tsGAG and tUA were higher in epidermis. In intrinsically aged buttock, epidermal HA and dermal tsGAG and tUA decreased. However, when analyzed for each gender, epidermal tsGAG, tUA, and tissue water decreased only in females. Forearm/buttock ratios of each molecule were compared for determination of photoaging-dependent changes. Forearm/buttock ratios of HA, tsGAG, tUA, and tissue water increased in aged dermis, but showed no change in aged epidermis. When analyzed for each gender, ratios of epidermal HA and tissue water increased only in aged females, while ratios of epidermal tsGAG, tUA, and tissue water decreased only in aged males. Correlations of water content with HA, tsGAG, and tUA were found in epidermis, but not with tsGAG in dermis. These intrinsic aging- and photoaging-dependent GAG changes and their correlations with water content provide new insights into the pathophysiology of dry skin in the elderly.

Lysophospholipids improve skin moisturization by modulating of calcium‐dependent cell differentiation pathway

Recent studies have demonstrated that lysophospholipids (LPL) play critical roles in several biological signal transduction pathways to maintain the homoeostasis of cells, tissues and organs. Among them, lysophosphatidic acid (LPA) has been identified as a lipid mediator that induces morphological improvement in the epidermis in mice. In this study, we examined the effects of LPL (soybean-derived phospholipids modified with phospholipase A2 and C) compared with LPA. We initially examined the effects of LPA on normal human epidermal keratinocytes (NHEK) focusing on the expression of profilaggrin and serine palmitoyltransferase (SPT) mRNAs. LPA enhanced the expression of profilaggrin and SPT mRNAs via the modulation of Ca(2+) influx. Based on those results, the influence of LPL on NHEK was examined and was expanded to analyse the expression of two tight junction-related proteins, occludin and claudin-1. LPL had similar effects to increase profilaggrin and SPT mRNA expression and also stimulated the expression of occludin and claudin-1 at the mRNA and protein levels. In accordance with these results, LPL elicited significant improvements in surface water content in human skin. These findings indicate that LPL has the potential to strengthen the skin moisturizing capability by up-regulating the expression of mRNAs encoding components important to skin barrier function and skin hydration.

The effect of N‐acetyl‐glucosamine on stratum corneum desquamation and water content in human skin

Alpha-hydroxy acids have been used topically to treat skin for both dermatological and cosmetic problems for many years. Though there are many known benefits of the use of alpha-hydroxy acids on skin, there have been recent reports that topical treatments with alpha-hydroxy acids increase skin damage resulting from UVB. Additionally, high concentrations of alpha-hydroxy acids by themselves have also been found to cause skin irritation. In order to find alternatives to alpha-hydroxy acids, we investigated a variety of amino sugar compounds that were previously reported to inhibit the reaggregation of dissociated corneocytes by modulating cellular adhesion. In vivo, we observed that topical treatments with a formulation containing N-acetyl-glucosamine (NAG) led to an increase in skin moisturization, a decrease in skin flakiness, and the normalization of stratum corneum exfoliation. In vitro, we observed an upregulation of differentiation markers, keratin 10 and involucrin, in keratinocytes treated with NAG. CD44 is a lectin cell adhesion molecule that is also expressed in keratinocytes. Amino sugars such as NAG may competitively bind to CD44, modulating keratinocyte cellular adhesion. We hypothesize that these amino sugars modulate keratinocyte cellular adhesion and differentiation, leading to the normalization of stratum corneum exfoliation. We propose the use of amino sugars such as NAG as alternative compounds to replace the use of alpha-hydroxy acids in skin care.

Millimeter wave reflectivity used for measurement of skin hydration with different moisturizers

A new non-invasive method for determining the free water content in human skin has been developed. The method analyzes the reflection of millimeter (mm) wavelength electromagnetic waves. The amount of reflection of mm waves depends on an electrical property (namely, the permittivity) of the skin, and this depends upon the free water content of the various skin layers. The aim of the present study was to use the mm wave reflectometry method for determination of free water content in healthy skin treated with different hydrating substances. Skin lotion, pure water, glycerol, and petroleum jelly (an occlusive substance) were used for hydration of skin. The amount of free water was calculated using the permittivity values of skin layers found from fitting a three layer skin model to measured reflection data. The skin model consisted of (1) the stratum corneum (SC), (2) the viable epidermis plus the dermis, and (3) fat layers. Mm wave reflection was significantly affected by the water content of the thick SC of the palm but not by the very thin SC of the forearm. Treatment of the forearm and palm skin with different hydrating substances produced notable changes of the free water content in the SC, but not in the viable epidermis or dermis. The greatest hydration was produced by pure water and skin lotion, and the lowest by petroleum jelly. However, petroleum jelly produced prolonged retention of water in the SC following its hydration by other moisturizers. The content of free water was found to return to its baseline value after removal of moisturizers in as short a time as 8.3 min. The study shows that mm wave reflectometry can be used as a sensitive technique for the non-invasive determination of water content in living skin.

Regional Difference of Water Content in Human Skin Studied by Diffuse-Reflectance Near-Infrared Spectroscopy: Consideration of Measurement Depth

Diffuse reflectance (DF) spectra in the 1250-2500 nm region were measured in vivo for the skin of the forehead, cheek, jaw, elbow, volar forearm, palm, knee, and heel of seven healthy volunteers, using a Fourier transform near-infrared (FT-NIR) spectrophotometer with a fiber-optic probe. Apparent regional differences of water content in the skin, as estimated from the diffuse reflectance NIR spectra, are discussed in relation to the influence of measurement depth. The NIR spectra were collected with or without a 300 microm gap between the fiber-optic probe and the skin surface. For comparison, in vitro NIR spectra of stratum corneum sheets equilibrated at 41, 50, 63, and 81% relative humidity, at 25 degrees C, were also obtained. There was a difference in the ratio of the two water bands centered near 1450 nm and 1900 nm between the contact and non-contact measurements. In addition, regional differences of water content calculated from the peak height of the 1900 nm water band, which was normalized to the peak height of the 2175 nm amide band, were compared. The results of Monte Carlo simulation indicated that the apparent regional differences arise at least in part from differences in the measurement depth due to differences in specular reflection at the skin surface and in the thickness of the stratum corneum.