Identifying patterns behind the changes in skin pores using 3-dimensional measurements and K-means clustering.

BACKGROUND: Skin pores are structural features of the skin, which tend to change as the skin ages. Since previous studies measured pores two-dimensionally, precise measurements using three-dimensional imaging were needed to comprehensively understand skin pores. This study aimed to determine the patterns behind the changes in skin pores during one's lifetime and to identify new characteristics of the pores in aged. MATERIALS AND METHODS: Skin surface profiles were measured three-dimensionally from the cheeks of 101 Korean women from February to March 2020 to analyze the exact state of their pores. The researchers performed K-means clustering to classify the skin pores, and topographical features of pores were analyzed as well. Statistical analyses were performed to verify the differences in the skin pore characteristics among clusters and the correlation between clusters and ages. RESULTS: Skin pores were classified into five groups based on size, density, and elongation. The skin conditions of the cluster groups were well correlated with aging, despite excluding age as a factor in pore classification. Adjacent skin pores tend to connect in the elderly. CONCLUSION: Skin pores become larger and longer over time. Skin pores connect together in the elderly, which might be related to wrinkle formation. This phenomenon strongly suggests skin pores as a characteristic of aging skin and as a potential target for anti-aging treatment.

Influence of quarantine mask use on skin characteristics: One of the changes in our life caused by the COVID-19 pandemic.

BACKGROUND: The influence of various environmental factors on skin properties is well known. However, there is a lack of research into the effect of quarantine masks on skin properties, even though the use of masks has significantly increased after the COVID-19 outbreak. Therefore, this study aimed to investigate the influence of mask use on skin properties. MATERIALS AND METHODS: Twenty subjects were enrolled in this study. The subjects used approved quarantine masks for 6 hours a day for 2 weeks. We measured eight skin biophysical parameters: temperature, redness, pore volume, texture, elasticity, trans-epidermal water loss (TEWL), sebum content, and pH, and evaluated acne lesions before and after using quarantine masks. The evaluation was performed on the mask-wearing area of the face. RESULTS: Skin temperature, redness, and TEWL increased significantly after a 6-hour mask use, while the sebum content increased marginally. Skin elasticity was reduced by the use of masks over 1 and 2 weeks, whereas the pore volume and the number of acne lesions increased after a 2-week mask use. The skin changes caused by mask use showed sex-based differences in the skin elasticity (after 6 hours), redness, and roughness (after 2 weeks). CONCLUSIONS: The use of quarantine masks causes a change in the skin temperature, redness, and TEWL in the short term and in skin elasticity, pores, and acne in the long term. This study revealed that prolonged mask use could have negative effects on the skin.

Validation of the elastic angle for quantitative and visible evaluation of skin elasticity in vivo.

BACKGROUND: Reduction in skin elasticity due to aging causes skin sagging and wrinkles. Although there are various objective and reliable techniques for measuring skin elasticity, it is difficult to obtain a visual representation of skin elasticity with them. Therefore, we developed a novel device, the Swing anglemeter, and analyzed its effectiveness for measuring skin elasticity of the cheek. MATERIALS AND METHODS: Forty-five healthy Korean women (age, 23-60 years) participated. The Swing anglemeter works by dropping a rubber ball on a subject's cheek, which draws a curve as it collides with the cheek. After recording the movement of the ball using the slow-motion function on a mobile phone, we defined the maximum angle at which the ball bounces off the skin as the elastic angle, using frame-by-frame video analysis. Changes in the elastic angle were assessed according to age, and correlation with the Ballistometer® results (Dia-stron Ltd., Andover, UK) was analyzed for validation. RESULTS: Elastic angles differed significantly (P < .001) according to age. A negative correlation was found between the elastic angle and age (r = -.799, P < .001). Compared with the Ballistometer® measurements, the elastic angle was negatively correlated with alpha (r = -.570, P < .001); it was positively correlated with the mean coefficient of restitution and area (r = .602, P < .001 and r = .535, P < .001, respectively). CONCLUSION: The elastic angle is a useful parameter for reflecting skin elasticity, both quantitatively and visually. Our method can help subjects understand their skin elasticity status. Therefore, we expect the device will be utilized in various fields within the cosmetic industry.

Relationship of transcutaneous oxygen tension with age and skin elasticity in Korean women.

BACKGROUND: Oxygen has several positive effects on the skin, including improving collagen synthesis and accelerating wound healing. However, only a few studies have investigated the relationship between skin oxygenation and skin aging parameters. Therefore, this study aimed to assess the correlation between skin oxygenation and skin aging parameters-elasticity, hydration, sebum, color (lightness, redness), and blood perfusion-in Korean women. MATERIALS AND METHODS: We evaluated the transcutaneous partial pressure of oxygen, also known as transcutaneous oxygen tension (TcPO2 ), and skin aging parameters, including elasticity, hydration, sebum, color (lightness or redness), and blood perfusion, in the cheek of 34 healthy women (aged 20-69 years) and assessed the correlation between TcPO2 and other skin aging parameters using IBM SPSS Statistics 25 software (SPSS Inc). RESULTS: Facial TcPO2 was negatively correlated with age (P < .05). There were positive correlations between facial TcPO2 and elasticity parameters (P < .01). We noted no correlation between facial TcPO2 and skin lightness; however, skin lightness tended to slightly improve with increasing TcPO2 . Skin aging parameters, including hydration, sebum, skin redness, and blood perfusion, showed no correlations with TcPO2 . CONCLUSION: In Korean women, facial TcPO2 tends to decrease with increasing age and is positively correlated with gross, net, and biological skin elasticity. Therefore, this study demonstrated that oxygen tension of facial skin can be a major causative factor of skin aging.

Machine learning for the prediction of sunscreen sun protection factor and protection grade of UVA.

We report a prediction model for sunscreen sun protection factor (SPF) and protection grade of ultraviolet (UV) A (PA) based on machine learning. We illustrate with real clinical test results of UV protection ability of sunscreen for SPF and PA. With approximately 2200 individual clinical results for both SPF and PA level detection, individually, we were able to see that active ingredient information can provide accurate SPF and PA prediction rates through machine learning. Furthermore, we included four new factors-presence of pigment, concentration of pigment grade titanium dioxide, type of formulation and type of product-as additional information for the prediction model and were able to see increased prediction rates as results.

Two newly developed indices evaluating facial skin aging.

BACKGROUND: Skin assessment methodologies have focused mainly on intuitive aging characteristics, including facial wrinkles and pigmented spots, and usually adopt pattern recognition algorithms. Recently, distinct methods of interpreting skin aging, such as the detection of facial landmarks and age prediction using machine learning techniques, have been conducted. MATERIALS AND METHODS: We defined two indices that represent the severity of facial aging. The first index was the ratio of the bizygomatic distance and bigonial distance. The second index was the ratio of the degrees of the near mandible. The indices extracted from two-dimensional frontal face images were intended to show the deformation of the facial skin downward with aging progress. To validate whether these proposed indicators can represent facial aging, we conducted correlation tests with age and facial skin characteristics and performed association tests between the indices and facial skin characteristics, adjusted for age. RESULTS: The indices showed strong correlations with age (r = 0.557 and 0.464, respectively) and facial skin characteristics. Although there were correlations between the indices and facial skin features, the associations between the indices and facial skin characteristics adjusted for age were weak or not significant. This suggests that the newly developed indices are appropriate for evaluating facial skin aging and distinct from typical measurements. CONCLUSION: We suggest two novel indices for evaluating facial aging based on frontal face images. The indices exhibited strong correlations with age and representative facial skin characteristics. The newly developed values can be differentiated indicators of facial aging compared with general skin features.

Novel human skin surface antimicrobial peptide quantification method using a skin patch test chamber: A pilot study.

INTRODUCTION: Antimicrobial peptides (AMPs) on the skin surface are related to the innate immunity of the skin in preventing external infection. Skin rinsing and tape stripping (TS) are acceptable methods for analyzing AMPs on the skin surface but have limitations, such as causing skin damage. In this study, we proposed a noninvasive method to measure AMPs on the skin surface with minimal skin damage. METHODS: Using the patch test assay, we aimed to analyze the skin surface human ß-defensin (hBDs) levels without damaging the skin barrier. The concentrations of hBDs on the skin surface were evaluated through the skin patch testing of 13 healthy subjects, and hBD-1 concentrations were compared with those obtained using the TS method in this proof-of-concept study. In addition, changes in skin physiology and concentration of hBDs under 1% sodium lauryl sulfate stimulation were monitored in 14 healthy subjects (8 young and 6 elderly subjects) for 150 h. RESULTS: The correlation between the two methods had a Pearson's coefficient of 0.640, and skin patch analysis led to a relatively less impaired barrier with no significant increase in transepidermal water loss after analysis. Age-specific comparisons suggested that higher skin surface hBD-2 concentrations were present in the young group as compared with the elderly group. Skin surface expression of hBD-2 after skin barrier disruption was also higher in the young group. CONCLUSION: Our findings show that skin patch analysis is a convenient method to analyze hBDs on the skin surface. hBDs are factors of innate immunity that can be used as an index to predict a decreased chemical immune response of skin due to aging.

Development of the facial glycation imaging system for in situ human face skin glycation index measurement.

BACKGROUND: The accumulation of advanced glycation end products has been proposed as a causative agent of skin aging, but there are no conventional devices for quantifying advanced glycation end-product accumulation in facial skin. AIMS: This study aimed to develop a convenient and accurate in situ advanced glycation end-product measurement system for the human face. METHODS: We developed a facial glycation imaging system, which consisted of illumination (white light-emitting diode, ultraviolet light-emitting diode) and image acquisition modules to capture face images. Advanced glycation end product-related autofluorescence and total skin reflectance were calculated to obtain the skin glycation index using an image analysis algorithm. Correlations between the skin glycation index and facial skin elasticity and age were examined in 36 healthy Korean women. RESULTS: The facial glycation imaging system was validated against a volar forearm skin autofluorescence measurement device, that is, the AGE Reader mu, with forearm skin glycation index (R = 0.64, P < .01). Cheek elasticity was negatively correlated with cheek skin glycation index (R = -0.56, R = -0.57, and R = -0.61, P < .01 for R2, R5, and R7, respectively). Age was significantly correlated with forearm skin glycation index (R = 0.44, P < .01) and cheek skin glycation index (R = 0.48, P < .01). CONCLUSION: We successfully developed a novel in situ facial skin glycation index measurement device. Our convenient and accurate system enables in situ skin glycation index monitoring for skin aging studies such as those on anti-glycation cosmetics.

Biophysical characteristics of dandruff-affected scalp categorized on the basis of sebum levels.

BACKGROUND: Various sebum levels can be detected in dandruff-affected scalps. However, few studies have compared the biophysical characteristics of dandruff scalps categorized based on sebum levels. AIMS: To investigate and compare the biophysical characteristics of dandruff-affected scalps categorized based on sebum levels. METHODS: Fifty-four Korean women with dandruff and 30 healthy Korean women underwent physiological measurements, including evaluation of sebum and hydration levels, pH, and transepidermal water loss (TEWL) in the scalp. The levels of the biomarkers of interleukin-8 (IL-8) and kallikrein 5 (KLK5) and corneodesmosomes were investigated in the stratum corneum (SC) of the scalp. RESULTS: Dandruff was categorized as dry (low-sebum, n = 25) or oily (high-sebum, n = 29) based on a sebum cutoff level of 97.82 µg/cm2 . Both dry and oily dandruff-affected scalps showed significantly decreased hydration levels and increased pH and TEWL compared with healthy subjects, with hydration levels being lower in dry dandruff-affected scalps. IL-8 expression was significantly increased in the oily dandruff-affected scalp. In addition, both dry and oily dandruff-affected scalps showed significantly increased KLK5 levels in the SC, with the levels being higher in oily dandruff-affected scalps. Altered distribution of corneodesmosomes, present on the entire surface area of the corneocytes, was notable in oily dandruff-affected scalps. CONCLUSION: The biophysical characteristics of the two types of dandruff represent the influence of different characteristics, including hydration levels, expression of IL-8 and KLK5, and corneodesmosome distribution. Thus, strategies to reduce dandruff levels should differ according to sebum levels.

Effect of the skincare product on facial skin microbial structure and biophysical parameters: A pilot study.

Daily use of cosmetics is known to affect the skin microbiome. This study aimed to determine the bacterial community structure and skin biophysical parameters following the daily application of a skincare product on the face. Twenty-five Korean women, who used the same skincare product for four weeks participated in the study. During this period, skin hydration, texture, sebum content, and pH were measured, and skin swab samples were collected on the cheeks. The microbiota was analyzed using the MiSeq system. Through these experiments, bacterial diversity in facial skin increased and the microbial community changed after four weeks of skincare product application. The relative abundance of Cutibacterium and Staphylococcus increased, significant changes in specific bacterial modules of the skin microbial network were observed, and skin hydration and texture improved. It was suggested that daily use of skincare products could affect the microbial structure of facial skin as well as the biophysical properties of the facial skin. These findings expand our understanding of the role of skincare products on the skin environment.

A study correlating between instrumental and consumers' subjective luster values in oriental hair tresses.

Hair luster has long been a key objective for consumers in the hair care market and many researchers have sought to quantitate the luster of hair fibers or tresses. Recently, a fast polarimetric video camera called SAMBA with a high polarization contrast was introduced that can effectively separate specular and diffuse light. Instrumental measurement of shine using SAMBA was conducted to quantitate the luster on phenyl trimethicone-treated hair tresses. We confirmed with atomic force microscopy that phenyl trimethicone's luster-enhancing effect was related to its reduction of hair surface. Panel tests by 15 untrained panelists were carried out to determine whether their assessment corresponded with instrumental results. The instrumental data showed an excellent correlation with subjective assessments from the 15 panelists. This study shows that SAMBA has utility as an instrumental technique for hair luster evaluation and is in good agreement with consumers' subjective evaluation of luster.

Partially purified paeoniflorin exerts protective effects on UV-induced DNA damage and reduces facial wrinkles in human skin.

Partially purified paeoniflorin (PF), a new cosmetic ingredient from roots of Paeoniae lactiflora, has been developed. Its paeoniflorin content is about 64%, far higher than that of conventional, cosmetic-grade peony root extracts (approximately 10%). In this report, we studied the effects of PF on UV-induced DNA damage in both cultured human keratinocytes and hairless mouse skin. We also investigated the anti-wrinkle effects of PF-containing cosmetic preparations on human skin. From the in vitro and in vivo comet assay, it was revealed that PF protected cells from DNA damage induced by ultraviolet B (UVB) irradiation in both cultured normal human keratinocytes (19.4% decrease at 0.001%) and hairless mouse skin keratinocytes (41% decrease at 0.01%). An eight-week clinical trial using 0.5% PF-containing formulation with 20 volunteers resulted in a statistically significant reduction in facial wrinkles (p < 0.05). These results suggest that the partially purified paeoniflorin has potent anti-aging and anti-wrinkle activities and should be a useful ingredient for these purposes.

Penetration enhancement in mouse skin and lipolysis in adipocytes by TAT-GKH, a new cosmetic ingredient.

Since the basic domain of human immunodeficiency virus type I (HIV-1) transactivator of transcription (TAT) protein was reported to possess the ability to traverse biological membranes efficiently, various therapeutic proteins have been attached to TAT for the purpose of therapy. In this study, the tripeptide GKH (glycine-lysine-histidine) derived from parathyroid hormone (PTH), known as lipolytic peptide, was attached to 9-poly lysine (TAT) to be used as a cosmetic ingredient in slimming products. TAT-GKH at 10(-5) M induced approximately 37.6% and 41.5% maximal lipolytic effects in cultured 3T3-L1 differentiated adipocytes and in epididymal adipocytes isolated from rats, respectively, compared with basal lipolysis. The lipolytic effect of GKH was not changed by TAT-GKH fusion. In cytotoxicity tests, there was no cytotoxicity in any dose concentration of TAT-GKH. We confirmed that TAT-GKH induced lipolytic activity by GKH without cytotoxicity and with the possibility of its use as a safe cosmetic ingredient. TAT-GKH elevated penetration into excised hairless mice skin 36 times more efficiently than GKH. TAT-GKH can be used as a cosmetic ingredient in slimming products, with both penetration enhancement and lipolytic effect without cytotoxicity.