Novel double staining of the stratum corneum with fluorescent ε-poly-l-lysine and anionic dextran.

OBJECTIVE: ε-Poly-l-lysine (PLL) is a cationic polymer consisting of 25-35 l-lysine residues. Our previous study revealed that fluorescently labelled PLL can stain the stratum corneum (SC) via ionic interactions between PLL and SC constituents. In this study, to further clarify the mechanisms underlying the interaction between PLL and the SC, the staining properties of fluorescent PLL were compared with that of fluorescently labelled anionic dextran (aDex), which has approximately the same molecular weight as PLL. METHODS: SC samples were collected by non-invasive tape stripping and stained with fluorescent PLL and/or fluorescent aDex. Fluorescence images were acquired using a fluorescence microscope and then analysed. RESULTS: The SC could be stained with either fluorescent PLL or aDex, both of which were inhibited by the addition of high concentrations of salt solutions. In particular, aDex staining was inhibited at a lower salt concentration than PLL staining. Moreover, PLL staining was inhibited under acidic conditions, while aDex staining was inhibited under neutral to alkaline conditions. Double staining of SC with both fluorescent polymers produced heterogeneous staining patterns: corneocytes stained with both polymers, corneocytes stained with PLL or aDex in a mutually exclusive manner, and unstained corneocytes. Staining of SC samples from the face was more extensive than staining of SC samples from the inside of the upper arm with both polymers. In addition, pretreatment of the SC with ethanol resulted in enhanced staining with both polymers. These results suggest that double staining of SC with both polymers can provide information on the damaged SC. CONCLUSION: Staining of SC with fluorescent PLL depends on its properties of a cationic and hydrophobic polymer with appropriate molecular size, which can distinguish the damaged SC. Double staining of SC with fluorescent PLL and aDex is a novel approach to obtain information for the analysis of skin conditions.

OBJECTIF: La ε-poly-L-lysine (PLL) est un polymère cationique constitué de résidus de 25 à 35 L-lysines. Notre précédente étude a révélé que la PLL marquée par fluorescence peut colorer le stratum corneum (SC) par des interactions ioniques entre la PLL et les constituants du SC. Dans cette étude, afin de clarifier davantage les mécanismes sous-jacents à l'interaction entre la PLL et le SC, les propriétés de coloration de la PLL fluorescent ont été comparées à celles du dextran anionique (aDex) marqué par fluorescence, qui a à peu près le même poids moléculaire que la PLL. MÉTHODES: Les échantillons SC ont été prélevés par «tape stripping¼ non invasif et colorés avec de la PLL fluorescente et/ou de l'aDex fluorescent. Les images de fluorescence ont été acquises au microscope à fluorescence puis analysées. RÉSULTATS: Le SC pouvait être coloré avec de la PLL ou de l'aDex fluorescents, tous deux inhibés par l'ajout de fortes concentrations de solutions salines. En particulier, la coloration par aDex était inhibée à une concentration en sel inférieure à la coloration par PLL. En outre, la coloration de la PLL a été inhibée dans des conditions acides, tandis que la coloration de l'aDex a été inhibée dans des conditions neutres à alcalines. La double coloration de SC avec les deux polymères fluorescents a produit des modes de coloration hétérogènes: cornéocytes colorés avec les deux polymères, cornéocytes colorés avec de la PLL ou de l'aDex d'une manière mutuellement exclusive, et cornéocytes non colorés. La coloration des échantillons de SC sur le visage était plus étendue que la coloration des échantillons de SC sur la face intérieure du haut du bras avec les deux polymères. En outre, le prétraitement du SC avec de l'éthanol a entraîné une coloration améliorée avec les deux polymères. Ces résultats indiquent qu'une double coloration du CS avec les deux polymères peut fournir des informations sur le CS endommagé. CONCLUSION: La coloration du CS avec de la PLL fluorescente dépend de ses propriétés de polymère cationique et hydrophobe de taille moléculaire appropriée, ce qui permet de distinguer le CS endommagé. La double coloration de SC avec de la PLL et de l'aDex fluorescents est une nouvelle approche pour obtenir des informations pour l'analyse des affections cutanées.

Staining of stratum corneum with fluorescent ε-poly-L-lysine and its application to evaluation of skin conditions.

BACKGROUND: ε-Poly-L-lysine (PLL) is a cationic polymer consisting of 25 to 35 L-lysine residues that adheres to the surface of skin as well as hair. However, the properties of PLL regarding its adhesion to the skin remain to be elucidated. In this study, we examined the staining of stratum corneum (SC) with fluorescence-labeled PLL and explored its relationship with skin condition. MATERIALS AND METHODS: Alexa Fluor 488-labeled PLL (AF-PLL) was reacted with tape-stripped stratum corneum (SC), and the staining properties were monitored by fluorescence microscopy. Clinical study was performed by measuring the water content of the cheek SC and transepidermal water loss (TEWL), and the tape-stripped SC was subjected to staining with AF-PLL. RESULTS: AF-PLL staining of the SC was inhibited at acidic pH or by the addition of high concentration of salt solution, suggesting the involvement of ionic interaction between PLL and the SC, at least in part. The AF-PLL staining was inhibited by unlabeled PLL or various alkyl amines, but not by L-lysine monomer. AF-PLL staining was observed inside the corneocytes as well as surrounding cornified envelope. Clinical study revealed that AF-PLL staining intensity of the SC was negatively correlated with its water content and positively correlated with its TEWL. CONCLUSION: PLL can efficiently adhere to SC and AF-PLL staining of SC can be applied to evaluate skin conditions.

Changes in facial moisture distribution and feelings of moisture/dryness among various environmental temperatures and humidities in summer and winter.

BACKGROUND: As environmental conditions vary depending on area of residence, consideration of environmental temperature and humidity conditions is crucial for detection of actual skin conditions in daily life. In this study, we determined changes in facial moisture and sensory evaluation distributions in various environmental temperature and humidity conditions. MATERIALS AND METHODS: An original near-infrared (NIR) imaging system was used to obtain moisture distributions. Sensory evaluations of feelings of moisture/dryness were graded, and changes were compared among 10 healthy Japanese female subjects in four different environmental temperature and humidity conditions (28°C, 60% RH; 28°C, 20% RH; 15°C, 60% RH; 15°C, 20% RH) in summer and winter. RESULTS: Skin moisture was lower at high temperatures and higher at low temperatures. Feelings of dryness on bare skin were high in low humidity. Sensitivity of feelings of moisture and dryness was high around the center of the cheekbones between side of the eyes and the mouth, but the same was not true of the moisture distribution. Moisture level was lower in winter at high temperatures, especially under the eyes near the side of the nose ridge, while the sense of dryness was not strong. These divergences between sensory evaluation and moisture level indicate the presence of a "hidden dry situation." CONCLUSION: Changes in moisture level and sensory evaluation scores in facial skin varied among environmental conditions, which differed between summer and winter, even under the same environmental temperature and humidity.

Self-Assembled Fullerene Crystals as Excellent Aromatic Vapor Sensors.

Here we report the aromatic vapor sensing performance of bitter melon shaped nanoporous fullerene C60 crystals that are self-assembled at a liquid-liquid interface between isopropyl alcohol and C60 solution in dodecylbenzene at 25 °C. Average length and center diameter of the crystals were ca. 10 µm and ~2 µm, respectively. Powder X-ray diffraction pattern (pXRD) confirmed a face-centered cubic (fcc) structure with cell dimension ca. a = 1.4272 nm, and V = 2.907 nm³, which is similar to that of the pristine fullerene C60. Transmission electron microscopy (TEM) confirmed the presence of a nanoporous structure. Quartz crystal microbalance (QCM) results showed that the bitter melon shaped nanoporous C60 performs as an excellent sensing system, particularly for aromatic vapors, due to their easy diffusion through the porous architecture and strong π⁻π interactions with the sp²-carbon.

1-(2-Hydroxyethyl)-2-imidazolidinone, a heparanase and matrix metalloproteinase inhibitor, improves epidermal basement membrane structure and epidermal barrier function.

Daily exposure to sunlight is known to affect the structure and function of the epidermal basement membrane (BM), as well as epidermal differentiation and epidermal barrier function. The aim of this study is to clarify whether the inhibition of BM-degrading enzymes such as heparanase and matrix metalloproteinase 9 (MMP-9) can improve the epidermal barrier function of facial skin, which is exposed to the sun on a daily basis. 1-(2-hydroxyethyl)-2-imidazolidinone (HEI) was synthesized as an inhibitor of both heparanase and MMP-9. HEI inhibited not only the BM damage at the DEJ but also epidermal proliferation, differentiation, water contents and transepidermal water loss abnormalities resulting from ultraviolet B (UVB). This was determined in this study by the use of UVB-induced human cultured skins as compared with the control without HEI. Moreover, topical application of HEI improved epidermal barrier function by increasing water content and decreasing transepidermal water loss in daily sun-exposed facial skin as compared with non-treated skins. These results suggest that the inhibition of both heparanase and MMP-9 is an effective way to care for regularly sun-exposed facial skin by protecting the BM from damage.

Visualization of Water Distribution in the Facial Epidermal Layers of Skin Using High-Sensitivity Near-Infrared (NIR) Imaging.

Skin moisturization is an important function of cosmetics in dermatology, and acquisition of two-dimensional information about the water content of facial skin is of great interest. Near-infrared (NIR) imaging using the water OH band centered near 1460 nm has been applied to the evaluation of water in skin. However, detection of small changes in the water content of skin water is difficult using this band because of the low absorption coefficient of water at that wavelength and inadequate optical units. We developed a high-sensitivity water imaging system using strong water bands centered near 1920 nm. This system can be used for the entire face. With the water imaging system, time-dependent changes in the water content of moisturizer-treated skin and hair were visualized with high sensitivity. In this study, we performed a water distribution analysis, with the aim of understanding the water distribution in facial skin under different environmental conditions. The water imaging system combines a diffuse illumination unit and an extended-range indium-gallium arsenide NIR camera with a detection range of 1100-2200 nm. The skin water distributions for multiple subjects with different facial shapes and sizes were compared using averaged NIR image data and a mesh partition analysis using a developed algorithm. Changes in the facial skin water content with season and humidity were visualized by the algorithm. The water content decreased in autumn, especially near the eyes and upper-cheek. Compared to other areas on the face, the water content around the eyes decreased more during an 85 min stay in a room at 10% relative humidity. The proposed method for water distribution analysis provides a powerful tool for facial skin hydration research in dermatological and cosmetics fields.

Image analysis of skin color heterogeneity focusing on skin chromophores and the age-related changes in facial skin.

BACKGROUND/PURPOSE: Heterogeneity with respect to skin color tone is one of the key factors in visual perception of facial attractiveness and age. However, there have been few studies on quantitative analyses of the color heterogeneity of facial skin. The purpose of this study was to develop image evaluation methods for skin color heterogeneity focusing on skin chromophores and then characterize ethnic differences and age-related changes. METHODS: A facial imaging system equipped with an illumination unit and a high-resolution digital camera was used to develop image evaluation methods for skin color heterogeneity. First, melanin and/or hemoglobin images were obtained using pigment-specific image-processing techniques, which involved conversion from Commission Internationale de l'Eclairage XYZ color values to melanin and/or hemoglobin indexes as measures of their contents. Second, a spatial frequency analysis with threshold settings was applied to the individual images. Cheek skin images of 194 healthy Asian and Caucasian female subjects were acquired using the imaging system. Applying this methodology, the skin color heterogeneity of Asian and Caucasian faces was characterized. RESULTS: The proposed pigment-specific image-processing techniques allowed visual discrimination of skin redness from skin pigmentation. In the heterogeneity analyses of cheek skin color, age-related changes in melanin were clearly detected in Asian and Caucasian skin. Furthermore, it was found that the heterogeneity indexes of hemoglobin were significantly higher in Caucasian skin than in Asian skin. CONCLUSION: We have developed evaluation methods for skin color heterogeneity by image analyses based on the major chromophores, melanin and hemoglobin, with special reference to their size. This methodology focusing on skin color heterogeneity should be useful for better understanding of aging and ethnic differences.

Motion-artifact-robust, polarization-resolved second-harmonic-generation microscopy based on rapid polarization switching with electro-optic Pockells cell and its application to in vivo visualization of collagen fiber orientation in human facial skin.

Polarization-resolved second-harmonic-generation (PR-SHG) microscopy is a powerful tool for investigating collagen fiber orientation quantitatively with low invasiveness. However, the waiting time for the mechanical polarization rotation makes it too sensitive to motion artifacts and hence has hampered its use in various applications in vivo. In the work described in this article, we constructed a motion-artifact-robust, PR-SHG microscope based on rapid polarization switching at every pixel with an electro-optic Pockells cell (PC) in synchronization with step-wise raster scanning of the focus spot and alternate data acquisition of a vertical-polarization-resolved SHG signal and a horizontal-polarization-resolved one. The constructed PC-based PR-SHG microscope enabled us to visualize orientation mapping of dermal collagen fiber in human facial skin in vivo without the influence of motion artifacts. Furthermore, it implied the location and/or age dependence of the collagen fiber orientation in human facial skin. The robustness to motion artifacts in the collagen orientation measurement will expand the application scope of SHG microscopy in dermatology and collagen-related fields.

Imaging of hemoglobin oxygen saturation ratio in the face by spectral camera and its application to evaluate dark circles.

BACKGROUND: Contact-type spectrophotometers have been widely used to measure skin color to determine the color values and melanin and hemoglobin contents. Recently, a spectral camera was introduced to evaluate two-dimensional color distribution. However, its application to skin color measurement has been limited. METHODS: The original spectral imaging system developed for facial skin consisted of a spectral camera and an original lighting unit for uniform irradiation of the face. The distribution of skin chromophores in the face, including melanin and oxy- and deoxyhemoglobin, was calculated from the reflectance data for each pixel of the spectral images. In addition, to create a mean spectral image of the group, a face morphing technology for spectral data was proposed. Using the system, we determined the characteristics of the dark circles around the eyes and also evaluated the effects of an anti-dark circle cosmetic. RESULTS: This system enabled the sensitive detection of skin chromophores in the face. Melanin content increased and hemoglobin oxygen saturation ratio decreased locally in the infraorbital areas of women with dark circles compared with those of women without dark circles. In addition, we were able to detect improvement in the dark circles after 6 weeks' use of anti-dark circle cosmetic products by visualizing the distribution of the relative concentrations of melanin and hemoglobin oxygen saturation ratio. CONCLUSION: Using a spectral camera, we developed a non-contact image-processing system that was capable of capturing a wide area of the face to visualize the distribution of the relative concentrations of skin chromophores in the face.

The relationship between the Young's modulus of the stratum corneum and age: a pilot study.

BACKGROUND/PURPOSE: The mechanical properties of the stratum corneum play an important role in protecting the body from external physical stimuli and excessive sensitivity. However, it is difficult to analyze these mechanical properties in vivo. To resolve this problem, we carried out a numerical analysis to calculate the Young's modulus of the stratum corneum. We then investigated the relationship between the Young's modulus of the stratum corneum and age. METHODS: We used a Cutometer(®) and a Dermal Torque Meter(®) for measuring skin mechanical parameters, and optical coherence tomography and an ultrasonic imaging system for measuring skin thickness. Based on these non-invasive results, liner elastic analysis was performed by the finite element method, and the Young's moduli of the stratum corneum and the dermis were calculated by solving an inverse problem. Using these techniques, we analyzed the correlation between the Young's modulus of the stratum corneum for the cheeks of seventy-eight Japanese women aged from 20 to 68 years. RESULTS: In the group study, the mean Young's moduli of the stratum corneum and dermis were calculated 1.993 MPa and 0.066 MPa, respectively. While carrying out individual analyses, there was a weak relationship between the Young's modulus of the stratum corneum and age (r = 0.337). CONCLUSION: We calculated the Young's modulus of the stratum corneum in vivo, with commercially available systems, and found that it is a weak correlation with age in this group of subjects. Future developments of our method would be beneficial in the characterization of facial skin aging and the validation of cosmetic and medical applications.

Stratum corneum drying drives vertical compression and lipid organization and improves barrier function in vitro.

The stratum corneum dehydrates after exogenous hydration due to skincare or bathing. In this study, sheets of stratum corneum were isolated from reconstructed human epidermis and the barrier function and structure of these sheets were assessed during drying with the aim of improving our understanding of skincare. Water diffusion through the sheets of stratum corneum decreased with drying, accompanied by decreased thickness and increased visible light transmission through the sheets. Electron paramagnetic resonance revealed that the order parameter values of stratum corneum lipids increased with drying. X-ray diffraction analysis revealed increases in the diffraction intensity of lamellar structures, with an 11-12 nm periodicity and spacing of 0.42 nm for lattice structures with drying. These results suggest that the drying process improves the barrier function of the stratum corneum by organizing the intercellular lipids in a vertically compressed arrangement.

In vivo observation of age-related structural changes of dermal collagen in human facial skin using collagen-sensitive second harmonic generation microscope equipped with 1250-nm mode-locked Cr:Forsterite laser.

In vivo visualization of human skin aging is demonstrated using a Cr:Forsterite (Cr:F) laser-based, collagen-sensitive second harmonic generation (SHG) microscope. The deep penetration into human skin, as well as the specific sensitivity to collagen molecules, achieved by this microscope enables us to clearly visualize age-related structural changes of collagen fiber in the reticular dermis. Here we investigated intrinsic aging and/or photoaging in the male facial skin. Young subjects show dense distributions of thin collagen fibers, whereas elderly subjects show coarse distributions of thick collagen fibers. Furthermore, a comparison of SHG images between young and elderly subjects with and without a recent life history of excessive sun exposure show that a combination of photoaging with intrinsic aging significantly accelerates skin aging. We also perform image analysis based on two-dimensional Fourier transformation of the SHG images and extracted an aging parameter for human skin. The in vivo collagen-sensitive SHG microscope will be a powerful tool in fields such as cosmeceutical sciences and anti-aging dermatology.

Improvement of skin surface texture by topical estradiol treatment in climacteric women.

BACKGROUND: Hormone replacement therapy (HRT) has been widely applied to climacteric women to improve various climacteric symptoms. Purpose of the present study is to reveal the effect of topical HRT with estradiol on skin surface texture (SST), a major determinant of skin appearance. METHODS: Estradiol 1.08 mg in gel was topically applied daily to the upper limbs of menopausal or ovariectomized women for 8 weeks. Thereafter, lower-dose estradiol 0.54 mg or placebo gel was applied for a further 16 weeks. Images of SST in the flexor forearm and cheek were captured by video microscope; fineness of texture as revealed by the number of ridges was calculated by image analysis. RESULTS: Increase in fineness of texture by topical HRT during 8 weeks was observed not only in the forearm, where estradiol was applied, but also in the cheek, an unapplied site. In women receiving topical estradiol, the fine texture tended to decline slightly but nonsignificantly during the consecutive 16-week low-dose HRT period whereas it was markedly declined in those receiving placebo gel. CONCLUSION: Topical HRT can improve age-associated decline of fineness of SST.

Light source spectrum strongly influences the in vitro estimation of sun protection factor.

Irradiation from an artificial solar simulator that matches the relative cumulative erythema effectiveness (RCEE) of sunlight is used for in vivo sun protection factor (SPF) testing, whereas irradiation that matches the spectrum of natural sunlight (NS) is generally used for in vitro SPF testing. This study was designed to clarify whether this difference is important. Eight sunscreens spread on artificial substrates and several optical filters as sunscreen mimics were used. Their in vitro SPF values were evaluated using RCEE-compliant and NS spectrum-matching light sources in calculation. The calculated in vitro SPF values obtained using NS light (SPF [NS]) were lower than those obtained using RCEE light (SPF [RCEE]). The in vitro SPF (RCEE) values showed a better correlation and better agreement with in vivo SPF values, as compared with the in vitro SPF (NS) values. A marked difference between in vitro SPF values obtained with the two light sources in calculation was found for sunscreens showing low transmittance in the ultraviolet B region. To obtain in vitro SPF values that correspond well to in vivo SPF values measured with currently accepted methodology, it is important to use an RCEE-compliant light source.

Influence of application amount on sunscreen photodegradation in in vitro sun protection factor evaluation: proposal of a skin-mimicking substrate.

Widely used polymethylmethacrylate substrates for in vitro sun protection factor (SPF) testing of sunscreens do not mimic the rough surface structure of skin, and in addition, sample loading is less than that used in in vivo SPF testing (2.00 mg cm(-2)). We have developed a skin-mimicking substrate (SMS), which has furrows and ridges on its surface, like human skin. A comparison of the photodegradation profiles of sunscreens on commercially available substrates (including SMS) at the recommended application amounts, and on SMS at various application amounts showed that the photodegradation rate of photounstable sunscreen was dependent on the application amount being higher at lower application amounts. SMS at the recommended application amount of 2.00 mg cm(-2) provided in vitro SPF values that were comparable with in vivo SPF values. Our results confirm that, in order to develop a reliable in vitro SPF method, which is consistent with in vivo SPF determination, it is important to use the same application amount of sample as in the in vivo method, in order to take proper account of sunscreen photostability.

Dermal carbonyl modification is related to the yellowish color change of photo-aged Japanese facial skin.

BACKGROUND: The photo-aged facial skin is characterized by various unique features such as dark spots, wrinkles, and sagging. Elderly people, particularly Asians, tend to show a yellowish skin color change with photo-aging. However, there has been no analytical study conducted on this unique skin color change of the aged facial skin. OBJECTIVE: The purpose of the present study is to examine whether the carbonyl modification in the dermal protein is involved in the yellowish color change that occurs in the photo-aged skin. METHODS: Normal skin samples excised from the face, abdomen and buttock of variously aged Japanese were separated into the epidermal and the dermal portions. These skin samples were histologically examined for carbonyl modification. Moreover, an in vitro constructed dermis model composed of a contracted collagen gel was treated with acrolein or 4-hydroxynonenal. All these samples were also studied colorimetrically. RESULTS: The dermal samples obtained from the photo-aged facial skin exhibited an appearance of yellowish color, whereas neither the facial epidermis nor the dermis obtained from the abdomen or buttock showed such a yellowish discoloration. The upper layer of the dermis that revealed the yellowish color showed elastosis whose elastic fibers were found to colocalize with carbonyl protein as detected by a labeled hydrazide, as well as by an immunohistochemical examination using the antibody against acrolein adduct. Experimental induction of carbonyl modification in a dermis model in vitro by a long-term treatment with acrolein or 4-hydroxynonenal was found to show the appearance of the yellowish change which was also proven by an increase in b* value of colorimetry. It was more pronounced than that induced by glycation. CONCLUSION: Our present results strongly suggest that carbonyl modification of the dermal protein is involved in the production of the yellowish color change that is noted in the photo-aged facial skin.

Comparison of sagging at the cheek and lower eyelid between male and female faces.

BACKGROUND: Facial sagging is a well-known morphological feature associated with aging and reduced dermal elasticity. Its morphological characteristics and mechanism have been studied in females, but it is unclear whether or not there is a gender difference. AIMS: The aim of this study was to clarify the morphological characteristics of sagging and the mechanism of sagging formation in male faces as compared with female faces, focusing on changes in dermal elasticity. METHODS: Faces of 98 healthy Japanese male volunteers, in their 20s-60s, were photographed at an angle of 45°. Upper and lower cheek sagging severity was evaluated by using photograph-based grading criteria. In addition, new photograph-based grading criteria of sagging severity at the lower eyelid were established and used. Dermal elasticity was measured using a non-invasive, in vivo suction skin elasticity meter, Cutometer(®). Furthermore, photographs of 108 healthy Japanese female volunteers in their 20s-60s were used to compare the difference in the morphological characteristics of sagging between males and females. RESULTS: Male facial sagging was prominent at the lower eyelid, upper cheek and lower cheek. Sagging severity in the upper and lower cheek was almost the same between males and females at all ages, whereas sagging at the lower eyelid in males was significantly more severe than that in females after middle age. Although dermal extensibility (U(f)) was not related to age, total deformation recovery (U(a)), -(amount of deformation) -(U(f)-U(a)), overall elasticity of the skin including creep and creep recovery (U(a)/U(f)), net elasticity excluding viscoelastic creep (U(r)/U(e)), ratio of elastic recovery to total deformation (U(r)/U(f)) and -(ratio of viscoelastic to elastic distention) -(U(v)/U(e)) were all significantly negatively related to age in both men and women. Furthermore, as in female faces, male facial sagging was significantly negatively related to dermal elasticity parameters, such as -(U(f)-U(a)), U(a)/U(f), U(r)/U(e) and U(r)/U(f). CONCLUSION: These results indicate that the morphology and areas of sagging in male faces are similar to those in females in the cheek, but sagging at the lower eyelid is more severe in males after middle age. Furthermore, the dermal elasticity of male facial skin decreased with age similar to that of females, and may therefore be associated with the sagging formation in male faces.

Increased carbonyl protein level in the stratum corneum of inflammatory skin disorders: A non-invasive approach.

The stratum corneum (SC) is the interface of body and environment, and is continuously exposed to oxidative stress, resulting in carbonyl modification of proteins. We have developed a simple and non-invasive method to assess carbonyl protein (CP) level in the SC, applied it to various kinds of skin, and revealed a link between the stratum corneum carbonylated protein (SCCP) level and water content in the SC. The purpose of the present study is to examine the SCCP level in inflammatory skin disorders associated with xerosis. Psoriasis vulgaris (PV) and atopic dermatitis (AD) are typical inflammatory skin disorders, of which the stratum corneum shows markedly low water content. SC samples were non-invasively collected from the lesional and non-lesional areas of PV and AD by adhesive tape stripping, and their carbonyl groups were determined by reaction with fluorescein-5-thiosemicarbazide. The average fluorescence intensity of the SC was calculated as SCCP level. Higher SCCP level was observed in the lesional area of PV as compared with non-lesional area or healthy control. Lesional area of AD also exhibited higher SCCP level than corresponding non-lesional area, of which SCCP level was slightly higher than the healthy control. These data suggest the involvement of oxidative modification of the SC protein, at least in part, in generation of xerotic skin in inflammatory skin disorders as well as dry skin in healthy subjects.

An innovative method to measure skin pigmentation.

BACKGROUND/PURPOSE: It is crucial to establish an accurate method for measuring skin pigmentation in cosmetic science and clinical dermatology. Here, we report a non-invasive precise method for measuring skin melanin content. METHODS: In order to determine the concentrations of melanin and hemoglobin in skin, we used the spectrum resolution (SR) method. In brief, the absorption spectrum of the skin was calculated from the reflection spectrum using a spectrophotometer. The concentrations of melanin and hemoglobin were then determined using a multiple regression analysis, assuming that the absorption spectrum of the skin is expressed as a linear summation of the absorptions of melanin and hemoglobin according to the Lambert-Beer law. The skin changes in the volar forearm, which had been irradiated by ultraviolet rays (UV), were observed daily by the SR method. RESULTS: A multiple regression analysis with an absorption spectrum of 500-700 nm was performed. The multiple correlation coefficient was 0.993, resulting in a satisfactory precise estimate of the concentrations of melanin. After UV irradiation, the concentration of melanin monitored by the SR method increased until 8 days and decreased gradually afterwards. CONCLUSIONS: The SR method allows the evaluation of the changes of epidermal melanin induced by UV irradiation.