Appearance Of Human Skin Research Articles

Hidden Links Between Skin Microbiome and Skin Imaging Phenome.

Despite the skin microbiome has been linked to skin health and diseases, its role in modulating human skin appearance remains understudied. Using a total of 1244 face imaging phenomes and 246 cheek metagenomes, we first established three skin age indices by machine learning including skin phenotype age (SPA), skin microbiota age (SMA), and skin integration age (SIA) as surrogates of phenotypic aging, microbial aging, and their combination, respectively. Moreover, we found that besides aging and gender as intrinsic factors, skin microbiome might also play a role in shaping skin imaging phenotypes (SIPs). Skin taxonomic and functional α diversity was positively linked to melanin, pore, pigment, and ultraviolet spot levels, but negatively linked to sebum, lightening, and porphyrins levels. Furthermore, certain species were correlated with specific SIPs, such as sebum and lightening levels negatively correlated with Corynebacterium matruchotii, Staphylococcus capitis, and Streptococcus sanguinis. Notably, we demonstrated skin microbial potential in predicting SIPs, among which the lightening level presented the least error of 1.8%. Lastly, we provided a reservoir of potential mechanisms through which skin microbiome adjusted the SIPs, including the modulation of pore, wrinkle, and sebum levels by cobalamin and heme synthesis pathways, predominantly driven by Cutibacterium acnes. This pioneering study unveils the paradigm for the hidden links between skin microbiome and skin imaging phenome, providing novel insights into how skin microbiome shapes skin appearance and its healthy aging.

Effect of Oral Intake of Flammulina velutipes (Enokitake) on Skin Condition in Healthy Adult Women: A Randomized, Double-Blind, Placebo-Controlled Study on Mental and Physical Health

Nutritional foods are concentrated sources of molecules with a nutritional or physiological effect which contain nutrients. There is a category, “nutricosmetics”, defined as ingestible natural health products that enhance the function and appearance of human skin, nails, and hair. A new variety of Flammulina velutipes (F. velutipes), Oki-Shirayuki 919, was explored to ascertain whether its components have functions of nutricosmetics. We focused on physiological effects for enhancing the human skin condition, such as moisturizing or barrier functions in F. velutipes. A randomized, double-blind, placebo-controlled clinical study was performed between January and March 2022. Among healthy men and women (n = 30) aged 20 to 59 years, the test group (n = 15) took a test product which included F. velutipes dry powder, and the placebo group (n = 15) took a placebo (a similar product in which the F. velutipes dry powder was replaced with plum fruit paste). Since the amount of increase in skin hydration over four weeks in the test group was significantly larger than that in the placebo group, a significant difference between the two groups was observed (p = 0.033). F. velutipe was suggested to have some physiological functions such as improving skin moisture.

Age‐related changes in surface reflection, diffuse reflection, and subsurface scattering light of facial skin: Luminance value measured by the system for the optical properties of facial skin

AbstractWe have developed a system that separates and measures the optical properties of skin that determine its visual quality, that is, the surface reflection, diffuse reflection, and subsurface scattering components of the skin. This system includes two polarization filters that separate light from the skin into a surface reflection component image and a diffuse reflection component image. Furthermore, by using a projector as a light source and irradiating the skin using a high‐frequency binary illumination pattern, the subsurface scattering component image alone can be separated and generated. Application of an algorithm that calculates the luminance value Y for each component image not only makes it possible to analyze each light signal from the skin quantitatively, but also enables understanding of how each light signal is related to the skin's overall appearance. Using the proposed system, we performed a survey of 154 Japanese women aged from their 20s to their 70s and analyzed age‐related changes in the optical properties of their skin. The results revealed the following. First, the luminance value Y of the surface reflection from the cheek and its standard deviation within the analysis area increase with age. Second, the Y value of diffuse reflection from the skin decreases with age. Third, the amount of light in the subsurface scattering components also decreases with age. The proposed system is expected to be suitable for a wide range of applications, including color science, and various studies of the appearance of human skin.

Circ004463 promotes fibroblast proliferation and collagen I synthesis by sponging miR-23b and regulating CADM3/MAP4K4 via activation of AKT/ERK pathways

Skin thickness is closely related to the appearance of human skin, such as sagging and wrinkling, which primarily depends on the level of collagen I synthesized by fibroblasts in the dermal layer. To explore the underlying genetics of the development of skin thickness, we used the indigenous Chinese Chenghua pigs, considered to have superior skin thickness, as model animals. We first performed whole transcriptome sequencing analysis to identify significant skin morphological differences between Chenghua pigs and Large White pigs and obtained some differentially expressed coding RNAs (454 mRNAs) and noncoding RNAs (612 circRNAs, 188 miRNAs, and 19 lncRNAs); moreover, some competing endogenous RNA (ceRNA) networks were constructed. Interestingly, we then identified a circRNA, namely circ0044633, which plays an important role in promoting fibroblast proliferation along with myofibroblast transition and collagen I synthesis by sponging miR-23b and regulating CADM3 and MAP4K4 expression via activation of the downstream AKT and ERK pathways in vitro. Furthermore, overexpression of circ004463 increased the mouse skin thickness and collagen I content in vivo. These results revealed a whole transcript profile of skin tissue and identified an important circ0044633-miR-23b-CADM3/MAP4K4 axis related to fibroblast proliferation and collagen I synthesis during the development of skin thickness.

Small extracellular vesicles derived from dermal fibroblasts promote fibroblast activity and skin development through carrying miR-218 and ITGBL1

Skin thickness is closely related to the appearance of human skin, such as sagging and wrinkling, which primarily depends on the level of collagen I synthesized by dermal fibroblasts (DFs). Small extracellular vesicles (SEVs), especially those derived from human DFs (HDFs), are crucial orchestrators in shaping physiological and pathological development of skin. However, the limited supply of human skin prevents the production of a large amount of HDFs-SEVs, and pig skin is used as a model of human skin. In this study, SEVs derived from DFs of Chenghua pigs (CH-SEVs), considered to have superior skin thickness, and Large White pigs (LW-SEVs) were collected to compare their effects on DFs and skin tissue. Our results showed that, compared with LW-SEVs, CH-SEVs more effectively promoted fibroblast proliferation, migration, collagen synthesis and contraction; in addition, in mouse model injected with both SEVs, compared with LW-SEVs, CH-SEVs increased the skin thickness and collagen I content more effectively. Some differentially expressed miRNAs and proteins were found between CH-SEVs and LW-SEVs by small RNA-seq and LC–MS/MS analysis. Interestingly, we identified that CH-SEVs were enriched in miRNA-218 and ITGBL1 protein, which played important roles in promoting fibroblast activity via activation of the downstream TGFβ1-SMAD2/3 pathway in vitro. Furthermore, overexpression of miRNA-218 and ITGBL1 protein increased the thickness and collagen I content of mouse skin in vivo. These results indicate that CH-SEVs can effectively stimulate fibroblast activity and promote skin development and thus have the potential to protect against and repair skin damage.Graphical

Chromatic and luminance sensitivity for skin and skinlike textures.

Despite the importance of the appearance of human skin for theoretical and practical purposes, little is known about visual sensitivity to subtle skin-tone changes, and whether the human visual system is indeed optimized to discern skin-color changes that confer some evolutionary advantage. Here, we report discrimination thresholds in a three-dimensional chromatic-luminance color space for natural skin and skinlike textures, and compare these to thresholds for uniform stimuli of the same mean color. We find no evidence that discrimination performance is superior along evolutionarily relevant color directions. Instead, discriminability is primarily determined by the prevailing illumination, and discrimination ellipses are aligned with the daylight locus. More specifically, the area and orientation of discrimination ellipses are governed by the chromatic distance between the stimulus and the illumination. Since this is true for both uniform and textured stimuli, it is likely to be driven by adaptation to mean stimulus color. Natural skin texture itself does not confer any advantage for discrimination performance. Furthermore, we find that discrimination boundaries for skin, skinlike, and scrambled skin stimuli are consistently larger than those for uniform stimuli, suggesting a possible adaptation to higher order color statistics of skin. This is in line with findings by Hansen, Giesel, and Gegenfurtner (2008) for other natural stimuli (fruit and vegetables). Human observers are also more sensitive to skin-color changes under simulated daylight as opposed to fluorescent light. The reduced sensitivity is driven by a decline in sensitivity along the luminance axis, which is qualitatively consistent with predictions from a Von Kries adaptation model.

A surface roughening technique for maxillofacial prostheses

Giving a natural surface texture to the maxillofacial prostheses is one of the major goals for the maxillofacial prosthodontists. This article describes a technique for application of an antiskid epoxy resin to the surface of the definitive mold before pouring the maxillofacial silicone elastomer. This technique produces evenly distributed and same-size pores that are more similar to the natural appearance of human skin.

Multimodal mapping of human skin

The combination of coherent anti-Stokes Raman scattering (CARS), second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) imaging--referred to as multimodal imaging--provides complementary contrast based on molecular vibrations, the structure of various tissue components and endogenous fluorophores, respectively. To present a comprehensive overview of the appearance of human skin in multimodal imaging. Multimodal imaging of unstained skin cross-sections of 32 individuals was performed using a laser scanning microscope and picosecond laser pulse for excitation. The epidermis, dermis and subcutis are distinguishable in all three applied modalities, but are unveiled best in multimodal images. While the subcutis is dominated by the CARS signal, predominately SHG and the secondary TPEF signal detect the dermis. In contrast, no SHG signal is detected in the epidermis, whereas CARS and TPEF show equal contributions. Additionally, the appearance of the major skin appendages is described, i.e. the hair follicle, sebaceous and sweat glands, and blood vessels belonging to the vascular system. All four investigated functional units show a characteristic morphochemistry in TPEF and CARS, allowing identification of further subunits, e.g. the major components of the hair follicle, while the SHG signal delineates the localization of the functional units. Multimodal imaging is a powerful tool to investigate human skin by providing high contrast based on the molecular constitution. It is therefore suggested that multimodal imaging has a high potential in application to dermatological research and clinical diagnostics of various skin alterations.

Real-Time Rendering for Multi-Layered Translucent Materials such as Human Skin under Dynamic Environment Lighting

Human skin is a highly scattering translucent material and is difficult to be scaled. In this paper, we combine approximation of specular reflection with subsurface scattering in the texture space and introduce the dynamic environment lighting to render the human skin to obtain a much more realistic expression. Considering lower computation and requirement for real-time, we use few spherical harmonics coefficients to represent the environment lighting approximated by the environment map. Further, by rotating the environment map, we obtain dynamic rendering effect of human skin appearance, which has a great practical value for creation of virtual character in real scene.

Simple and effective method for measuring translucency using edge loss: optimization of measurement conditions and applications for skin

We have developed a simple and effective method for everyday measurement of translucency with a handy spectral reflectometer using edge loss. Edge loss can be used to quantify the translucency index in terms of changes in reflectance under two types of measurement conditions. Here, a measurement condition represents the pairing of an illumination area and a measurement area. As a measure of the degree of lateral spread of reflected light, the translucency index can influence the appearance of human skin because this index represents eventual translucency. First, we estimated how edge loss changes when measurement conditions are varied. We then selected the combination of two measurement conditions of large and small edge loss to minimize errors. Finally, we estimated actual skin translucency changes before and after treatments comprising acetone-ether immersion and ultraviolet irradiation. The results were qualitatively consistent with the expectations under variations in absorbance and scattering capacity, indicating the effectiveness of this method in evaluating translucency. This method allows simultaneous measurement of translucency and reflectance as a spectrum, and also appears applicable for daily use, although common optical parameters cannot be derived using this method alone.

Subsurface scattering using splat-based diffusion in point-based rendering

Point-based graphics has gained much attention as an alternative to polygon-based approaches because of its simplicity and flexibility. However, current point-based techniques do not provide a sufficient rendering quality for translucent materials such as human skin. In this paper, we propose a point-based framework with subsurface scattering of light, which is important to create the soft and semi-translucent appearance of human skin. To accurately simulate subsurface scattering in multilayered materials, we present splat-based diffusion to apply a linear combination of several Gaussian basis functions to each splat in object space. Compared to existing point-based approaches, our method offers a significantly improved visual quality in rendering human faces and provides a similar visual quality to polygon-based rendering using the texture space diffusion technique. We demonstrate the effectiveness of our approach in rendering scanned faces realistically.

Reflectance of human skin using colour photometric stereo: with particular application to pigmented lesion analysis

The optical appearance of human skin is highly dependent on the interaction between the illumination (type and position), observer position and the skin surface structure. Different currently available photographic techniques record different aspects of this appearance, each providing its own incomplete description. This limits their usefulness, especially for pigmented skin lesion diagnosis. In this paper a new, easy to use, low-cost photographic method is described,which aims to generate an efficiently encoded yet reasonably complete representation of skin appearance. A prototype hand-held camera was developed that rapidly acquires six colour images, each with the skin illuminated from a different direction. A novel photometric stereo processing was used to combine these into a colour image of the skin's diffuse reflectance, independent of the skin surface topography, as well as a separate representation of that topography in the form of a surface gradient image. Images of four clinical pigmented skin lesions were evaluated in comparison with conventional digital photographs by both visual judgement and automated lesion boundary detection. The new colour reflectance images were free from the effects of topographical shading, shadowing and specular reflections. Lesion boundaries obtained automatically from the reflectance images were always closer to the outline drawn by a dermatologist than those obtained from conventional photographs. Finally, recombining the colour reflectance and surface gradient data to form a virtual image of the skin surface that is highly realistic in appearance. The new colour photometric stereo camera produces images of skin and skin tumours in which the reflectance information that is related to subsurface pigment distribution is separated from the surface topographic information. The total information generated by the system, for use in visual or automated analysis, is potentially greater than that for either conventional photography or dermatoscopy alone. Its further development and broader clinical evaluation are warranted to determine its usefulness and role in a wide range of dermatological tasks, including tele-dermatology applications.

Investigation of interactions between silicones and stratum corneum lipids

Ingredients of topically applied skin care formulations have not only positive effects on the appearance of human skin but can also disturb the Stratum corneum (SC) lipid barrier. In the present study, the influence of silicones (PDMS), as often used cosmetic ingredients, on the microstructure of SC lipids was investigated. For this purpose the interactions of four different PDMS with excised human SC were examined first using differential scanning calorimetry (DSC) and wide angle X-ray diffraction for physical characterization. Because the physical properties of human stratum corneum strongly depend on the lipid composition, showing inter-and intra-individual differences, the interactions with an in vitro model lipid system containing SC fatty acids were also studied, using polarized light microscopy, transmission electron microscopy, small angle X-ray diffraction and DSC. The results revealed that the investigated PDMS do not change either the microstructure of excised human SC or the biphasic lamellar/inverse hexagonal structure of the in vitro model. We concluded that PDMS will not cause any side-effects when topically applied and that our simplified in vitro model could be helpful for estimating interactions between cosmetic ingredients and other topically applied substances and the skin barrier at an early moment of formulation development.