A comprehensive in vivo study of Caucasian facial skin parameters on 442 women

Epidermal and dermal hydration in relation to skin color parameters

BACKGROUND

Our goal was to investigate linkages between skin color parameters and skin hydration. Since most prior studies focused on stratum corneum hydration, we focused on epidermal and dermal hydration in relation to skin color parameters in both sexes.

MATERIALS AND METHODS

Thirty adults (16 female) with an age ± SD of 24.3 ± 0.6 years participated. Three sites on both volar forearms were evaluated for melanin index (MI), erythema index (EI), Individual Typology Angle (ITA), tissue dielectric constant (TDC) values to depths of 0.5 mm (TDC0.5) and 2.5 mm (TDC2.5), and Fitzpatrick skin type (FST).

RESULTS

MI and EI were highly correlated (r = 0.800, p < 0.001) with maximum differences in MI and ITA along the arm of 3% and 6.3% with no difference between arms. Male MI was greater than females (p < 0.01). Male TDC2.5 was 36.1 ± 5.4 and correlated with EI (r = 0.231, p = 0.035). Contrastingly, female TDC25 was 28.5 ± 3.6 with no correlation with EI but was correlated with MI (r = -0.301, p = 0.003). These differential patterns held true for TDC0.5. For both sexes, FST and ITA were highly correlated (r = -0.756, p < 0.001).

CONCLUSIONS

The findings revealed several correlations between skin color parameters and hydration that differed between males in females in some cases. The observed correlations may indicate that melanin may differentially impact water-holding capacity between sexes and provides a future research target. Further, these initial findings also may hold significance for dermatological assessments and the customization of skincare treatments tailored to individual skin types and demographics.

Exploratory study on the body distribution of skin color, pigmentation and, degree of tan in Central European Caucasian Women

It is well known that skin color varies by body site and with season. However, little quantitative data on the topography of skin color and pigmentation are available. Therefore, exploratory cutaneous colorimetric measurements in 20 in central European Caucasian women aged 20 to 60 years have been made at 18 body sites. Tri-stimulus L*a*b*-values, hue, and chroma are considered to describe skin color. Based on the "Individual Typology Angle", the "Degree of Tan" was introduced to quantify the difference between constitutive and facultative pigmentation. Measurements were done in late winter and early summer to estimate potential changes by solar ultraviolet radiation. These measurements made evident that skin color obviously differs across the body in late winter. Even nearby body sites can be recognized as differently colored. A remaining degree of tan was found at permanent and intermittent exposed body sites. The remaining tan was not most pronounced at the permanently exposed sites but on the intermediate ones like the shoulder. In early summer, the degree of tan has most developed at the hands, arms, and instep, followed by the face. This study showed that besides basic differences between body sites in winter, accumulation, and degradation of tan also vary between body sites.

Diversity of Asian skin: A review on skin biophysical properties

Asian is home to dozens of different ethnic groups that are characterised by fascinating social and cultural variations. Unfortunately, existing literature on the skin properties of Asians tends to group this diverse population solely based on skin colour, perpetuating the misconception and stereotype that all Asian skin is the same. While Asia is one of the largest continents in the world, the difference in the geographical location and climate have long shaped the population into various ethnic groups with significant differences in the collective and diverse customs, traditions, cultures and living habits. The diverse ethnic groups in this region hint us that their skin biophysical characteristics can be very different from each other. This review features the profiling of the distinctive skin biophysical properties of Asians. We learn more about the different ethnic groups in Asia and acknowledge the unique skin biophysical properties even from the same country.

Correlating facial skin parameters with age and gender in population of Shaanxi Province, China

OBJECTIVE

This study was designed to comprehensively evaluate the changes in facial skin biophysical parameters with age, as well the influence of gender differences in populations of Shaanxi Province, China.

METHODS

Fourteen skin parameters, including stratum corneum hydration (SCH), transdermal water loss (TEWL), erythema, melanin, R0, R2, R5, R7, F4, gloss, skin surface pH, skin erythema index (a*), wrinkle length, and sebum, were measured by noninvasive instruments in 481 volunteers from Shaanxi Province. Spearman correlation analysis was performed to analyze the relationship between skin parameters and age. Additionally, skin parameters were analyzed for different age groups and different genders.

RESULTS

The results of the study showed a linear decrease in skin surface pH and sebum content with age, and the skin elasticity parameters R0, R2, R5, and R7 decreased significantly at the age of 54-65 years. Wrinkle length showed a linear and increase with age. R5 showed a weak negative correlation with age, R2, R7, and sebum content showed a moderate negative correlation, while wrinkle length showed a strong positive correlation. Considering the effect of gender on skin parameters, the results showed that SCH and gloss were lower in men than in women, while TEWL, erythema, melanin, wrinkle length, and sebum were higher than in women. However, there was no difference in skin elasticity between them.

CONCLUSION

The facial skin parameters, especially for the wrinkle length, exhibited the strong correlation relationship with ages in Shaanxi Province. Meanwhile, most skin parameters show significant differences with gender, which can provide a reference for future research and development in the field of cosmetics.

Stability Profile and Clinical Evaluation of an Innovative Hydrogel Containing Polymeric Micelles as Drug Delivery Systems with Oregano Essential Oil against Fibroepithelial Polyps

Skin tags, also known as fibroepithelial polyps (FPs) or acrochordons, are soft, pigmented excrescences, with a prevalence of 50-60% in the population, occurring especially in the fourth decade of life. To date, FPs have been efficiently eliminated using minimum invasive methods such as surgical removal, cauterization, laser irradiation, and cryosurgery. Over-the-counter treatments are also of interest for patients due to their non-invasive character, but their clinical efficiency has not been clearly demonstrated. This study was designed in order to evaluate the efficacy of a modern-pharmaceutical-formulation-type poloxamer-based binary hydrogel, having Origanum vulgare L. essential oil (OEO-PbH) as an active ingredient in the management of FPs. The formulation has been shown to possess good qualities in terms of stability and sterility. Non-invasive measurements revealed changes in some physiological skin parameters. An increase in transepidermal water loss (TEWL) and erythema index was noted, while skin surface water content (SWC) decreased during eight weeks of treatment. The macroscopic evaluation revealed that the FPs dried and shrunk after topical treatment with OEO-PbH. Clinically, patients presented a lowering of the number of lesions on the treated area of 20-30% after one month of treatment and around 50% after the second month. Histopathological examination suggests that topical treatment with OEO-PbH may induce histological changes in the epidermis, dermis, and fibrovascular cores of FPs, including a loss of thickness, reduced size and number of blood vessels, and low cellularity. These changes may contribute to the observed reduction in size of FPs after treatment with OEO-PbH.

Shotgun metagenomic sequencing reveals skin microbial variability from different facial sites

Biogeography (body site) is known to be one of the main factors influencing the composition of the skin microbial community. However, site-associated microbial variability at a fine-scale level was not well-characterized since there was a lack of high-resolution recognition of facial microbiota across kingdoms by shotgun metagenomic sequencing. To investigate the explicit microbial variance in the human face, 822 shotgun metagenomic sequencing data from Han Chinese recently published by our group, in combination with 97 North American samples from NIH Human Microbiome Project (HMP), were reassessed. Metagenomic profiling of bacteria, fungi, and bacteriophages, as well as enriched function modules from three facial sites (forehead, cheek, and the back of the nose), was analyzed. The results revealed that skin microbial features were more alike in the forehead and cheek while varied from the back of the nose in terms of taxonomy and functionality. Analysis based on biogeographic theories suggested that neutral drift with niche selection from the host could possibly give rise to the variations. Of note, the abundance of porphyrin-producing species, i.e., Cutibacterium acnes, Cutibacterium avidum, Cutibacterium granulosum, and Cutibacterium namnetense, was all the highest in the back of the nose compared with the forehead/cheek, which was consistent with the highest porphyrin level on the nose in our population. Sequentially, the site-associated microbiome variance was confirmed in American populations; however, it was not entirely consistent. Furthermore, our data revealed correlation patterns between Propionibacterium acnes bacteriophages with genus Cutibacterium at different facial sites in both populations; however, C. acnes exhibited a distinct correlation with P. acnes bacteriophages in Americans/Chinese. Taken together, in this study, we explored the fine-scale facial site-associated changes in the skin microbiome and provided insight into the ecological processes underlying facial microbial variations.

Cyclic changes of sensory parameters in migraine patients

BACKGROUND

Migraine shows a cyclic pattern with an inter-ictal-, a pre-ictal, an ictal- and a post-ictal phase. We aimed to examine changes in psychophysical parameters during the migraine cycle.

METHODS

The perception of nociceptive and non-nociceptive stimuli and an electrically induced axon-reflex-erythema were assessed in 20 healthy controls and 14 migraine patients on five consecutive days according to different phases of the migraine cycle. Pain was rated three times during a 10-second electrical stimulus. The size of the axon-reflex-erythema was determined using laser-Doppler-imaging. Intensity and hedonic estimates of odours presented by Sniffin' Sticks were rated.

RESULTS

In healthy controls, no significant changes over the test days were observed. In migraine patients pain thresholds at the head decreased with an ictal minimum. Less habituation after five seconds of stimulation at the head was found pre-ictally, whereas reduced habituation to 10-second electrical stimulation was present in all phases. The axon-reflex-erythema size showed an inter-ictal-specific minimum at the head. odours were perceived ictally as more unpleasant and intense.

CONCLUSIONS

Somatosensory functions, pain thresholds and habituation as predominantly central parameters, axon-reflex-erythema as a peripheral function of trigeminal neurons and odour perception as a predominantly extra-thalamic sensation change specifically over the migraine cycle indicating complex variations of neuronal signal processing.

Facial Skin Aging Stages in Chinese Females

Background

Facial skin is exposed to the environment, which marks it with obvious signs of aging. Based on multi-dimensional non-invasive evaluation data, female facial skin can be characterized in detail. However, there are few studies on the general aging rules of facial skin. Most skin aging studies divide the ages into 5-10-year intervals, so they have lacked dynamic matching with facial skin aging.

Aim

To explore facial skin aging rules, discuss the main parameters of facial skin aging, propose an unequal-distance aging division method based on the main skin parameters, and study the skin characteristics of Chinese women of different aging stages.

Methods

We comprehensively described the skin status as 24 non-invasive skin parameters belonging to five dimensions: skin wrinkles, texture, stain, color and barrier function. We performed polynomial fitting on the 21 skin parameters that were significantly correlated with age and derived the rules of aging in the different dimensions. Based on the wrinkle dimension, the facial skin aging process was divided into four stages, and the skin characteristics of the different stages were compared.

Results

Skin wrinkles increased, texture deteriorated, acne decreased, pigment spots increased, skin tone darkened, and sebum secretion decreased with age, according to the polynomial fitting. The aging stage was divided into an incubation period (18-30 years old), an aging occurrence period (31-42 years old), a rapid aging period (43-47 years old), and a stable aging period (48-60 years old), according to the wrinkles. Different aging stages had different skin characteristics.

Conclusion

The incubation period is the critical period for the appearance of skin stains; the skin texture gradually deteriorates during the aging occurrence period; the rapid aging period is a critical period for the aging of skin parameters; skin status during the stable aging period is the worst.

Evaluation of the changes in sebum, moisturization and elasticity in acne vulgaris patients receiving systemic isotretinoin treatment

AIM

The aim of this study was to determine the change in facial skin sebum, hydration and elasticity of acne vulgaris patients after being treated with systemic isotretinoin.

METHOD

Patients who were diagnosed with acne vulgaris and who received systemic isotretinoin treatment for 6 months in Cerrahpaşa Medical Faculty Department of Dermatology between June 2012 and May 2017 were included in this study. The sebum, hydration and elasticity of the skin were measured non-invasively with a device called "Soft Plus Skin Analyses System" before treatment and 6 months after treatment. The relationship between the pre-treatment and post-treatment values were evaluated statistically. 35 adult patients (20 female, 15 male) who were diagnosed with acne vulgaris and who received systemic isotretinoin treatment for 6 months.

RESULTS

The pre-treatment sebum value for both sexes ranged between 5 and 100 and the mean value was calculated as 75.8 ± 28.0. The post-treatment sebum values ranged between 1 and 98 and the mean value was calculated as 48.4 ± 31.8. The difference between the pre-treatment and post-treatment values was statistically significant, p < 0.001. The decline in sebum value after treatment was 36%. The pre-treatment hydration values ranged between 9 and 77.5 and the mean was 34.6 ± 14.6. The post treatment hydration values ranged between 4.8 and 100 and the mean was calculated as 62.4 ± 28.6. The difference between the pre-treatment and post-treatment hydration values were statistically significant, p < 0.001. The post-treatment increase in hydration was 79%. The pre-treatment skin elasticity ranged between 28 and 50; the mean was 40.4 ± 5.5. The post-treatment elasticity values ranged between 20 and 50; and the mean was 37.5 ± 8.2. However, the difference was not statistically significant (p = 0.1).

CONCLUSION

With this study, it was concluded that, systemic isotretion leads to a 36% decline in skin sebum values and a 79% increase in the skin hydration. However, the change in skin elasticity was not statistically significant. Furthermore, the changes in sebum and skin hydration did not lead to a change in skin elasticity.

Facial Skin Biophysical Profile of Women in Malaysia: Significance of Facial Skincare Product Use

INTRODUCTION

At present, there is a lack of baseline data on the facial skin biophysical profile of women in Malaysia. The implications related to the daily habits and facial skincare product use on the skin biophysical condition are, thus, unknown. In this study, we aim to evaluate facial skin biophysical parameters of Malaysian women and examine the influence of demographic characteristics, daily habits, and facial skincare product use on these parameters.

METHODS

Four skin biophysical parameters - transepidermal water loss (TEWL), melanin content, elasticity, and collagen intensity - were assessed on the cheek of the subjects (20-60 years). Demographic background, daily habits, and skincare product use were gauged through a survey. Only 197 from the 213 subjects recruited initially were used for analysis after the data were screened for normality.

RESULTS

The biophysical parameters were similar in different races, except a higher melanin content in Indian female individuals. Elasticity and collagen intensity reduced with age, while melanin content increased in the older age-groups. But no difference was observed in TEWL at different ages. Evaluating the influence of daily habits, we observed that exercise significantly lowered TEWL and increased melanin content, which may be associated with UV radiation exposure. Facial skincare products are popular among the female subjects (>85% users). Products with moisturizing, sunscreening, and other skincare functions (astringent, antiaging, and anti-wrinkle) were preferred by subjects of all ages. These product functions significantly improve skin elasticity and reduce melanin content in the young adults. While aged women recognized the importance of having an additional skin-lightening function in their skincare routine. Although the influence of individual skincare function on skin biophysical parameters was mostly positive, the alteration of these parameters varied at different ages.

CONCLUSION

This is the first report of facial skin biophysical profile of Malaysian women. There is no difference among 3 major races saved for melanin content. This work demonstrated age-dependent influences on the biophysical parameters, except TEWL. The significance of skincare product use is well reflected in the improvement of these parameters at different age-groups based on individual skincare functions.

Changes in Skin Barrier Function after Repeated Exposition to Phospholipid-Based Surfactants and Sodium Dodecyl Sulfate In Vivo and Corneocyte Surface Analysis by Atomic Force Microscopy

(1) Background: The aim of the study was to evaluate the effect of pure lecithins in comparison to a conventional surfactant on skin in vivo. (2) Methods: Physiological skin parameters were evaluated at the beginning and the end of the study (day 1 and day 4) (n = 8, healthy forearm skin) with an Aquaflux^®, skin-pH-Meter, Corneometer^® and an Epsilon^® sensor. Confocal Raman spectroscopy was employed to monitor natural moisturizing factor, urea and water content of the participants' skin. Tape strips of treated skin sites were taken and the collected corneocytes were subjected to atomic force microscopy. Circular nano objects were counted, and dermal texture indices were determined. (3) Results: Transepidermal water loss was increased, and skin hydration was decreased after treatment with SDS and LPC80. Natural moisturizing factor and urea concentrations within the outermost 10 µm of the stratum corneum were lower than after treatment with S75 or water. Dermal texture indices of skin treated with SDS were higher than skin treated with water (control). (4) Conclusions: Results suggest very good (S75) or good (LPC80) skin-tolerability of lecithin-based surfactants in comparison to SDS and encourage further investigation.

The Interaction of Age and Anatomical Region Influenced Skin Biophysical Characteristics of Chinese Women

BACKGROUND

Ageing is an inevitable physiology process of humans, and skin biophysical parameters change owing to genetic and environmental factors in different ethnic populations.

AIM

To gain comprehensive data on the skin biophysical parameters of different anatomical regions and to explore the change trend of the skin characteristics associated with age for the indicated regions by generalized additive model.

METHODS

We measured various skin biophysical parameters on forehead, cheek, chin and inner forearm of 178 Chinese women aged between 20 and 64 years living in Beijing. These parameters comprised skin hydration, transepidermal water loss (TEWL), sebum content, erythema index (EI), melanin index (MI), L*a*b* values, individual typology angle (ITA) and pH, which were quantified by non-invasive instruments.

RESULTS

Comparing the skin parameters among the four test areas, we observed that the hydration, TEWL, EI and a* values were significantly higher for the face than for the forearm, but the L* and ITA values were just the opposite. The cheek was the lightest and brightest region with lowest sebum content, while the chin was much darker and the forehead was yellowish. Considering the change of the skin parameters with age, TEWL, sebum content and melanin and erythema indices had a linear relationship with age, whereas skin hydration, L, a, b, ITA and pH values exhibited a non-monotonic relationship. The turning points of these curves appeared almost at the thirties, showing the lightest and evenest skin color and more hydration, with lower pH values.

CONCLUSION

This study indicates that the skin biophysical characteristics of Chinese women were significantly affected by age and body regions.

Seasonal variations in the skin parameters of Caucasian women from Central Europe

BACKGROUND

The human skin is greatly affected by external factors such as UV radiation (UVR), ambient temperature (T), and air humidity. These factors oscillate during the year giving rise to the seasonal variations in the skin properties. The aim of this study was to evaluate the effect of seasons, environmental T, relative and absolute humidity on the skin parameters of Caucasian women, perform a literature review and discuss the possible factors lying behind the found changes.

MATERIALS AND METHODS

We measured stratum corneum (SC) hydration, transepidermal water loss (TEWL), sebum level, erythema index, and elasticity parameters R2 and R7 on the forehead and the cheek of Caucasian women from the Czech Republic throughout the year. We also performed a non-systematic literature review focused on the seasonal variations in these skin parameters.

RESULTS

We confirmed a well-documented low SC hydration and sebum production in winter. In spring, we found the lowest TEWL (on the forehead) and the highest SC hydration but also the highest erythema index and the lowest elasticity presumably indicating skin photodamage. For most of the skin parameters, the seasonal variations probably arise due to a complex action of different factors as we extensively discussed.

CONCLUSION

The data about the seasonal variations in the skin parameters are still highly inconsistent and further studies are needed for better understanding of the normal skin changes throughout the year.

In Vivo Assessment of Water Content, Trans-Epidermial Water Loss and Thickness in Human Facial Skin

Mapping facial skin in terms of its biophysical properties plays a fundamental role in many practical applications, including, among others, forensics, medical and beauty treatments, and cosmetic and restorative surgery. In this paper we present an in vivo evaluation of the water content, trans-epidermial water loss and skin thickness in six areas of the human face: cheeks, chin, forehead, lips, neck and nose. The experiments were performed on a population of healthy subjects through innovative sensing devices which enable fast yet accurate evaluations of the above parameters. A statistical analysis was carried out to determine significant differences between the facial areas investigated and clusters of statistically-indistinguishable areas. We found that water content was higher in the cheeks and neck and lower in the lips, whereas trans-epidermal water loss had higher values for the lips and lower ones for the neck. In terms of thickness the dermis exhibited three clusters, which, from thickest to thinnest were: chin and nose, cheek and forehead and lips and neck. The epidermis showed the same three clusters too, but with a different ordering in term of thickness. Finally, the stratum corneum presented two clusters: the thickest, formed by lips and neck, and the thinnest, formed by all the remaining areas. The results of this investigation can provide valuable guidelines for the evaluation of skin moisturisers and other cosmetic products, and can help guide choices in re-constructive/cosmetic surgery.

Global data of unprotected skin minimal erythema dose relationship to Individual Typology Angle

BACKGROUND

Determination of the Minimal Erythema Dose (MED_u ) of unprotected skin is perhaps the most critical aspect of the Sun Protection Factor (SPF) value and disproportionately influences the SPF. Individual Typology Angle (ITA°), a skin reflectance measure of the skin's pigmentation, has been used by many clinical laboratories to estimate the MED_u values for SPF testing.

METHODS

Individual Typology Angle and unprotected MED_u data on 9931 individuals were received from 12 laboratories located on 5 continents to determine MED_u values in prospective sunscreen testing studies.

RESULTS

These data were compiled and normalized by laboratory (to account for differences in number of subjects within each laboratory). A polynomial regression best fits the relationship between ITA° and their MED_u and may be used to accurately predict the MED_u of an unknown test subject.

CONCLUSION

The regression data have been incorporated into the latest ISO24444 (Cosmetics - Protection test methods - in vivo determination of the sun protection factor (SPF), 2019) in vivo Sunscreen testing method that must be utilized to determine a subject's provisional MED_u for the testing procedure. Use of this common ITA°-MED_u relationship will help to minimize SPF variability between testing laboratories due to use of widely varying MED_u values.

Aging-associated alterations in epidermal function and their clinical significance

Chronologically-aged skin displays multiple functional changes in both the dermis and the epidermis. It appears that epidermal dysfunction, compromised permeability homeostasis, reduced stratum corneum hydration and elevated skin surface pH predispose to the development of aging-associated cutaneous and extracutaneous disorders. Improvements in epidermal function have been shown to be an effective alternative therapy in the prevention and treatment of some aging-associated cutaneous disorders, including eczematous dermatitis, pruritus, and xerosis. Recent studies demonstrated that epidermal dysfunction leads to the development of chronic, low-grade systemic inflammation, termed ‘inflammaging,’ which is linked to the development of aging-associated systemic disorders. Thus, correction of epidermal dysfunction could comprise a novel strategy in the prevention and treatment of aging-associated systemic disorders as well. In this review, we summarize aging-associated alterations in epidermal function, their underlying mechanisms, and their clinical significance. Regimens to improve epidermal function in the elderly are also discussed.

Objective measurement and comparison of human facial skin color in East Asian females

BACKGROUND

Skin color is an important physiological index of human skin that has essential significance in cosmetology and dermatological diagnoses and aesthetics, especially in East Asian culture, where the beauty standard is the whiter the skin, the more beautiful a person is. However, there has been a lack of objective comparisons of facial skin color in East Asian females.

MATERIALS AND METHODS

Skin color at the cheek site was measured in 445 healthy females, including 362 Chinese women in Beijing and 83 Japanese women in Tokyo, all aged 18-50 years. The parameters consisted of L^* , a^* , b^* , individual typology angle (ITA°), and hue angle and were determined using noninvasive skin measurement instruments.

RESULTS

The skin color categories in East Asians ranged from very light (I) to brown (V), and the dark (VI) category was not observed; the main categories were light (II), intermediate (III), and tan (IV). The facial skin color of Chinese individuals was brighter, more reddish, and less yellowish than that of Japanese individuals. With age, L* values decreased, and a* values and hue angle increased in East Asians with significant differences. Chinese women showed the same differences as Japanese women for all parameters in all age groups.

CONCLUSIONS

This study provides objective skin color measurements and examines significant differences with respect to geographic location and age.