Article

Ethnic skin types: Are there differences in skin structure and function?

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  • AVR Consulting Ltd
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Abstract

People of skin of colour comprise the majority of the world's population and Asian subjects comprise more than half of the total population of the earth. Even so, the literature on the characteristics of the subjects with skin of colour is limited. Several groups over the past decades have attempted to decipher the underlying differences in skin structure and function in different ethnic skin types. However, most of these studies have been of small scale and in some studies interindividual differences in skin quality overwhelm any racial differences. There has been a recent call for more studies to address genetic together with phenotypic differences among different racial groups and in this respect several large-scale studies have been conducted recently. The most obvious ethnic skin difference relates to skin colour which is dominated by the presence of melanin. The photoprotection derived from this polymer influences the rate of the skin aging changes between the different racial groups. However, all racial groups are eventually subjected to the photoaging process. Generally Caucasians have an earlier onset and greater skin wrinkling and sagging signs than other skin types and in general increased pigmentary problems are seen in skin of colour although one large study reported that East Asians living in the U.S.A. had the least pigment spots. Induction of a hyperpigmentary response is thought to be through signaling by the protease-activated receptor-2 which together with its activating protease is increased in the epidermis of subjects with skin of colour. Changes in skin biophysical properties with age demonstrate that the more darkly pigmented subjects retaining younger skin properties compared with the more lightly pigmented groups. However, despite having a more compact stratum corneum (SC) there are conflicting reports on barrier function in these subjects. Nevertheless, upon a chemical or mechanical challenge the SC barrier function is reported to be stronger in subjects with darker skin despite having the reported lowest ceramide levels. One has to remember that barrier function relates to the total architecture of the SC and not just its lipid levels. Asian skin is reported to possess a similar basal transepidermal water loss (TEWL) to Caucasian skin and similar ceramide levels but upon mechanical challenge it has the weakest barrier function. Differences in intercellular cohesion are obviously apparent. In contrast reduced SC natural moisturizing factor levels have been reported compared with Caucasian and African American skin. These differences will contribute to differences in desquamation but few data are available. One recent study has shown reduced epidermal Cathepsin L2 levels in darker skin types which if also occurs in the SC could contribute to the known skin ashing problems these subjects experience. In very general terms as the desquamatory enzymes are extruded with the lamellar granules subjects with lowered SC lipid levels are expected to have lowered desquamatory enzyme levels. Increased pores size, sebum secretion and skin surface microflora occur in Negroid subjects. Equally increased mast cell granule size occurs in these subjects. The frequency of skin sensitivity is quite similar across different racial groups but the stimuli for its induction shows subtle differences. Nevertheless, several studies indicate that Asian skin maybe more sensitive to exogenous chemicals probably due to a thinner SC and higher eccrine gland density. In conclusion, we know more of the biophysical and somatosensory characteristics of ethnic skin types but clearly, there is still more to learn and especially about the inherent underlying biological differences in ethnic skin types.

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... It has been reported that more darkly pigmented individuals retain skin properties that are younger compared with lighter-pigmented individuals. 21 The less pigmented skin seems more susceptible to photoaging and atrophies more rapidly compared with other ethnicities, and it would seem that light-pigmented Caucasian skin is aging faster and is clinically more fragile and thinner than darker skin. 13 This area of research, regarding facial skin pigmentation, ultraviolet exposure, skin thickness, and aging, needs further exploration. ...
... Although it would be naive to apply these heuristic shortcuts to all, fine rhytids have a greater propensity to develop earlier in Caucasians than in Hispanics, African Americans, and East Asians. 21 Therefore, traditional superficial musculoaponeurotic system (SMAS) face and neck lift techniques of Caucasians can predispose more to the delayed lateral or vertical sweep phenomenon seen postoperatively with these traditional techniques. The sweep phenomenon can be resistant to correction by revision with a repeat of the traditional SMAS facelift. ...
... Darker skin is generally accepted to maintain its elasticity for longer. 21 Therefore, direct neck approaches without skin excision are a possible option for such patients, even at relatively older ages. ...
Article
There is a significant ongoing shift in the utilization of cosmetic procedures across ethnicities.The most noticeable changes with age occur in all ethnicities over the mobile superficial musculo-aponeurotic system. Extended facelift techniques are most effective across all ethnicities by releasing the retaining ligaments. The complete release of the retaining ligaments of the midface and neck will facilitate the effective repositioning of soft tissue and allow for the best possible natural results. Opening the neck through a submental incision may be required for the effective management of deep neck problems.
... There are six major ethnic skin types; White Skin, Mediterranean Skin, Light Asian Skin, Dark Asian Skin, Africo Caribbean Skin and Mixed Skin [2]. Asians comprise about half of the world's population today, though literature concerning their skin is lacking. ...
... Asian skin is pigmented, has larger sweat glands and is smooth, and more prone to comedowns. It has a thicker dermis with large collagen bundles, and shows minimal Signs of aging, but conversely the epidermis is thinner, and has higher trans epidermal water loss [TEWL] and weaker barrier function upon chemical or mechanical challenge [2,3]. Furthermore, they hold higher risk of pigmentary side effects following procedures carried out on their skin [2]. ...
... It has a thicker dermis with large collagen bundles, and shows minimal Signs of aging, but conversely the epidermis is thinner, and has higher trans epidermal water loss [TEWL] and weaker barrier function upon chemical or mechanical challenge [2,3]. Furthermore, they hold higher risk of pigmentary side effects following procedures carried out on their skin [2]. However, the story of Asian skin is still is still not fully understood and remains a mystery due to lack of large-scale studies and overall poor economy of the countries in Asia. ...
... An obvious ethnic skin difference relates to colouration, both within and between human populations, which varies with melanin and haemoglobin. There is variation in the size, distribution, and autophagic degradation of melanosomes (which contain eumelanin and phaeomelanin) across ethnicities, producing variation in skin colouration, photo-protection, and ageing [30][31][32][33]. For example, lightlypigmented individuals have an earlier onset and more pronounced skin wrinkling and sagging signs, whereas darkly-pigmented individuals have more pigmentary problems. ...
... Previous research documents variation in the age of onset, severity, and concerns with skin ageing across ethnicities [32,34,60,61] and ethnic differences have partly been explained by structural and functional differences of skin types [62]. ...
... Thus, in addition to questions of noticeability, signs of ageing occur later in skin of colour [32] possibly because of the higher melanin content and the dispersal of melanosome in more darkly-pigmented skin [63]. Although higher melanin content correlates negatively with the onset and severity of photoaging in darker skin, there is also a greater risk of pigmentation alteration [32,34]. ...
Article
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Objective: Accuracy in assessing age from facial cues is important in social perception given reports of strong negative correlations between perceived age and assessments of health and attractiveness. In a multi-ethnic and multi-centre study, we previously documented similar patterns of female facial age assessments across ethnicities, influenced by gender and ethnicity of assessors. Methods: Here we extend these findings by examining differences between estimated age from digital portraits and chronological age (Δ age) for 180 women from three age groups (20-34, 35-49, 50-66 years) and five ethnicities (36 images of each ethnicity, assessed for age on a continuous scale by 120 female and male raters of each ethnicity). Results: Across ethnicities, Δ age was smallest in French assessors and largest in South African assessors. Numerically, French women were judged oldest and Chinese women youngest relative to chronological age. In younger women, Δ age was larger than in middle-aged and older women. This effect was particularly evident when considering the interaction of women's age with assessor gender and ethnicity, independently and together, on Δ age. Conclusion: Collectively, our findings suggest that accuracy in assessments of female age from digital portraits depends on the chronological age and ethnicity of the photographed women, and the ethnicity and gender of the assessor. We discuss the findings concerning ethnic variation in skin pigmentation and visible signs of ageing and comment on implications for cosmetic science.
... Asian skin may be more prone to irritation to specific topical agents compared with other skin types, most notably White skin. 16 Asian skin was reported to have an elevated neurosensory response to insults when compared with White skin and was more reactive than the skin of Black Americans. 17 Compared with White and Black skin, East Asian skin had the least skin barrier strength, the least maturation, and, consequently, the highest skin sensitivity. ...
... 18 Furthermore, some studies suggest Asian people may have more sensitive skin than other people. 16,17 Therefore it is crucial to select rosacea treatment that patients can tolerate. ...
Article
Background: Rosacea is primarily an inflammatory disease of facial skin associated with impaired skin barrier function. While it is commonly thought of as a Caucasian person's disease, it is likely underdiagnosed in people of color, including Asians, leading to missed and delayed diagnoses and increased morbidity. The purpose of this review is to highlight literature on rosacea in Asian people and the role of non-prescription skincare in managing rosacea. Methods: Four dermatologists (the panel) completed pre-meeting surveys and participated in a web meeting to discuss the role of skin care in treating rosacea in the Asia Pacific (APAC) region. The survey results were summarized, then presented during the virtual meeting. These survey results and relevant papers identified through a literature review were then discussed. This review shows the fruit of these discussions, as well as the advisors' expert opinions and experiences. Results: The panel crafted 5 consensus statements regarding the role of skin care in the treatment of rosacea in the APAC region. The most common forms of rosacea seen by the advisors are mostly erythematous and papulopustular. Among the panel, doxycycline is the most popular treatment for papulopustular rosacea. The panel prioritize gentleness when choosing skincare products for patients with rosacea. Conclusions: In Asian patients with rosacea, adjunctive skincare is an important part of treatment, maintenance, and prescription treatment. Given the highly sensitive skin of certain Asian patients with rosacea, avoiding potentially irritating substances is crucial. J Drugs Dermatol. 2023;22(1):45-53. doi:10.36849/JDD.7021.
... European skin is characterized by a relatively thin epidermis that undergoes further degeneration with time. 95 The thinner epidermis, with a more fragile system of barrier corneocytes and lipids, is also characteristic of East Asian skin. 90,95 Consequently, the skin is more sensitive to environmental pollutants causing inflammation and an increase in oxidative stress. ...
... 95 The thinner epidermis, with a more fragile system of barrier corneocytes and lipids, is also characteristic of East Asian skin. 90,95 Consequently, the skin is more sensitive to environmental pollutants causing inflammation and an increase in oxidative stress. 96,97 This can further facilitate enhanced microbial invasion with subsequent colonization of sebaceous glands and acne. ...
Article
Full-text available
Purpose: Personalized approaches in dermatology are designed to match the specific requirements based on the individual genetic makeup. One major factor accounting for the differences in skin phenotypes is single nucleotide polymorphism (SNP) within several genes with diverse roles that extend beyond skin tone and pigmentation. Therefore, the cellular sensitivities to the environmental stress and damage linked to extrinsic aging could also underlie the individual characteristics of the skin and dictate the unique skin care requirements. This study aimed to identify the likely biomarkers and molecular signatures expressed in skin cells of different ethnic backgrounds, which could aid further the design of personalized skin products based on specific demands. Methods: Using data mining and in-silico modeling, the association of SNP-affected genes with three major skin types of European, Asian and African origin was analyzed and compared within the structure-function gene interaction networks. Cultured dermal fibroblasts were subsequently subjected to ultraviolet radiation and oxidative stress and analyzed for DNA damage and senescent markers. The protective applications of two cosmetic ingredients, Resveratrol and Quercetin, were validated in both cellular and in-silico models. Results: Each skin type was characterized by the presence of SNPs in the genes controlling facultative and constitutive pigmentation, which could also underlie the major differences in responses to photodamage, such as oxidative stress, inflammation, and barrier homeostasis. Skin-type-specific dermal fibroblasts cultured in-vitro demonstrated distinctive sensitivities to ultraviolet radiation and oxidative stress, which could be modulated further by the bioactive compounds with the predicted capacities to interact with some of the genes in the in-silico models. Conclusion: Evaluation of the SNP-affected gene networks and likely sensitivities of skin cells, defined as low threshold levels to extrinsic stress factors, can provide a valuable tool for the design and formulation of personalized skin products that match more accurately diverse ethnic backgrounds.
... Pigmentation in SOC arises from elevated levels of melanin, which is synthesized by melanocytes in the basal layer of the epidermis and stored in melanosomes for trafficking to surrounding keratinocytes. Compared with lighter skin, darker skin tends to have higher melanin content and number of melanosomes, but no difference in the number of melanocytes is seen [5,15,[23][24][25][26]. The size and distribution of melanosomes follow a gradient across skin types, with smaller and grouped melanosomes in lighter skin and larger and non-grouped melanosomes in darker skin [15,27,28]. ...
... Whereas chronologic aging primarily presents with fine wrinkles, soft tissue volume loss, and increased skin laxity, photoaging is more likely to present with coarse wrinkles, telangiectasias, solar lentigines, mottled hyperpigmentation, and skin dullness [46,47]. Due to protection by epidermal melanin, individuals with SOC develop wrinkles from sun exposure later in life than those with lighter skin [23,[52][53][54][55]. Nevertheless, histological evidence of solar elastosis in sun-exposed skin has been observed in Hispanics [56], Asians [39], and African Americans [57,58]. ...
Article
Photoprotection behaviors can mitigate skin damage caused by ultraviolet radiation, and common methods include seeking shade, avoiding sun exposure during peak daylight hours, wearing sun-protective clothing, applying sunscreen, and using sunglasses. While the role of sun protection in preventing sunburns, photoaging, and skin cancer is well established in fair-skinned populations, individuals with skin of color (SOC) are presumed to suffer fewer negative effects from solar radiation. Thus, the importance of photoprotection in this population is understudied and may be underestimated. In SOC populations, sun exposure is known to cause pigmentary disorders, photoaging, and basal cell carcinoma (BCC), highlighting the potential benefits of photoprotection. Although SOC populations tend to practice photoprotection by seeking shade and wearing sun-protective clothing, survey and interview-based studies have consistently found relatively low use of sunscreen among these populations. Common motivators for photoprotection in individuals with SOC include preventing sunburn and pigmentation, with the prevention of skin cancer being a less important reason. As a skin cancer risk behavior, indoor tanning is relatively rare in SOC populations, but its use may increase with acculturation to US norms. While more studies are necessary to clarify whether photoprotection behaviors may decrease skin cancer-related mortality in SOC populations, regular dermatologic care and counseling on photoprotection remain essential in patients with SOC for overall skin health.
... Another factor that may affect the results is the difference in skin structure between Asian and Caucasian patients. Asian skin has the weakest barrier function and is more sensitive to exogenous chemical agents, probably because of the thinner layer of the stratum corneum and higher density of the eccrine glands [36,37]. The number of SSI cases in other developing countries, such as China and India, is also higher. ...
... Indonesia is a tropical country with a hot humid climate, with an average humidity level of 70%-90% for most of the year, which can cause excessive sweat production and itchiness to the patients' skin. As previously stated, the thin dermal layer of the auricle made this part more prone to SSIs [36,37]. ...
Article
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Objective This study aimed to investigate the functional outcomes, satisfaction, and quality of life of patients with microtia following reconstructive surgery. Methods This cross-sectional study was conducted using retrospective data of patients with microtia following reconstructive surgery using the Nagata technique. Data were obtained from the medical records of patients who underwent reconstructive surgery at the Division of Facial Plastic and Reconstructive Surgery, Department of Otorhinolaryngology, Head and Neck Surgery, Dr. Cipto Mangunkusumo Hospital between 2014 and 2018. All eligible patients were referred to participate in this study between November 2018 and March 2019. The hearing function was assessed by a professional audiologist after surgery. Patient satisfaction was evaluated by interview using a previously developed questionnaire, while quality of life was assessed using the EuroQol-5D-Young questionnaire. Results Thirty-one eligible subjects were included in the study. Pain and discomfort were the most commonly reported factors related to the quality of life following surgery. Approximately 67.7% of the patients were satisfied; 19.4% were very satisfied, and 12.9% reported acceptance of their surgical outcomes. The most common complication was infection (n = 8). Most patients did not experience any problems in their lives after microtia surgery. Conclusions The highest rate of satisfactory outcomes was observed for the lobule subunit, which was assumed to be associated with the use of the Z-plasty technique. The most common complication was infection, as environmental hygiene was the most important factor. Thus, further concern for maintaining good hygiene is necessary to improve the quality of reconstructive surgery. The level of satisfaction with microtia reconstructive surgery was adequate. Most patients had a good health-related quality of life without experiencing any problems.
... Age, gender, and ethnicity could also be important factors that result in inconsistency. It has been reported that human skin of different ethnic types shows clear differences in structure and function [61]. For example, Asian skin in general shows higher water contents and higher SC lipid levels [61]. ...
... It has been reported that human skin of different ethnic types shows clear differences in structure and function [61]. For example, Asian skin in general shows higher water contents and higher SC lipid levels [61]. Studies have shown that aging skin shows decreased epidermis thickness [62], is more susceptible to become dry in low-humidity environments and is often characterized by roughness and wrinkling [63]. ...
Article
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The non-ionizing and non-invasive nature of THz radiation, combined with its high sensitivity to water, has made THz imaging and spectroscopy highly attractive for in vivo biomedical applications for many years. Among them, the skin is primarily investigated due to the short penetration depth of THz waves caused by the high attenuation by water in biological samples. However, a complete model of skin describing the THz–skin interaction is still needed. This is also fundamental to reveal the optical properties of the skin from the measured THz spectrum. It is crucial that the correct model is used, not just to ensure compatibility between different works, but more importantly to ensure the reliability of the data and conclusions. Therefore, in this review, we summarize the models applied to skin used in the THz regime, and we compare their adaptability, accuracy, and limitations. We show that most of the models attempt to extract the hydration profile inside the skin while there is also the anisotropic model that displays skin structural changes in the stratum corneum.
... Cutaneous mechanical properties are closely related to the barrier function [4], hydration [5][6][7] and external skin appearance. They depend on age, phenotype, and biological sex [8][9][10]. ...
Article
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// OPEN ACCESS -> MDPI Cosmetics. // The investigation of the mechanical properties of skin is of great interest for monitoring physiological and pathological changes in the cutaneous barrier function for dermatological and cosmetic issues. Skin constitutes a complex tissue because of its multi-layered organisation. From a rheological point of view, it can be considered to be a soft tissue with viscoelastic properties. In order to characterise ex vivo mechanical properties of skin on the mesoscopic scale, a biosensor including a thickness shear mode transducer (TSM) in contact with a skin explant was used. A specific experimental set-up was developed to monitor continuously and in real-time human skin explants, including the dermis and the epidermis. These were kept alive for up to 8 days. Skin viscoelastic evolutions can be quantified with a multi-frequency impedance measurement (from 5 MHz to 45 MHz) combined with a dedicated fractional calculus model. Two relevant parameters for the non-destructive mesoscopic characterisation of skin explants were extracted: the structural parameter αapp and the apparent viscosity ηapp. In this study, the validity of the biosensor, including repeatability and viability, was controlled. A typical signature of the viscoelastic evolutions of the different cutaneous layers was identified. Finally, monitoring was carried out on stripped explants mimicking a weakened barrier function.
... It is established that the application of TU in a continuous mode increases the tissue temperature, associated with an increase in the distensibility of collagen in scar tissue 5 . This justifies the use of TU to increase tissue distensibility 17 . Previously, the effect of TU has been evaluated on the scars and skin grafts of burn victims, and although the authors did not find a significant increase in distensibility with TU, they found a significant improvement in the active and passive amplitude of the movement 7 . ...
Article
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Objective: This study aimed to compare the effects of therapeutic ultrasound and paraffin with or without vacuum massage on the biomechanical properties of grafted skin after a burn. Methods: A total of 44 patients with deep second- and third-degree burns, with a mean age of 35.89 (±11.53) years, who visited the Hospital Burn Unity, were included in the study. The therapeutic interventions were randomly defined by drawing lots, with a crossover design (crossover), and a minimum interval of 7 days (washout) between interventions. Skin biomechanical parameters such as distensibility (R0) and viscoelasticity (R6) were noninvasively evaluated by Cutometer before and after 0, 10, 20, and 30 min of intervention with therapeutic ultrasound and paraffin alone, as well as associated with negative pressure therapy of the skin (vacuum therapy). In this study, all groups showed increased distensibility (R0) in the period immediately after the application of the resources and a progressive reduction in the effects in the consecutive tests. Participants with skin grafts showed a decrease in viscoelasticity (R6) in all groups, except therapeutic paraffin and therapeutic ultrasound and vacuum massage. Conclusion: The biomechanical properties of grafted skin after a burn are altered after therapeutic intervention with ultrasound alone or associated with vacuum massage, such as intervention with paraffin associated with vacuum massage, for both parameters evaluated, skin distensibility (R0) and skin viscoelasticity (R6). However, the same did not occur for the intervention with isolated paraffin. There was no significant difference between the interventions therapeutic ultrasound and therapeutic paraffin.
... Higher rates of facial sebum production may be associated with larger pore sizes [5]. Skin oiliness and pore size may differ by race, with some studies demonstrating larger amounts of sebum secretion or larger pore sizes in Black patients [1,6,7] and others finding no difference [8,9]. Sebum composition and production can also vary by age and gender, and in patients with or without acne [10][11][12][13][14]. ...
Article
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Background Excessive sebum production is a factor in acne development. Tazarotene 0.045% lotion has demonstrated reductions in acne lesions and acne-induced sequalae. Objective Evaluate efficacy, changes in skin oiliness, and safety with tazarotene 0.045% lotion in participants with moderate-to-severe acne and oily skin. Methods In two phase 3, double-blind, 12-week studies (NCT03168321; NCT03168334), participants aged ≥9 years with moderate-to-severe acne were randomized 1:1 to once-daily tazarotene 0.045% lotion or vehicle lotion (N = 1,614). This pooled, post hoc analysis included only participants self-categorized with oily skin at baseline on the Acne Quality of Life questionnaire item 19 (scores: 0 [extremely oily] to 6 [not at all oily]). Inflammatory/noninflammatory lesion counts, treatment success, skin oiliness, treatment-emergent adverse events (TEAEs), and cutaneous safety/tolerability were evaluated. Results In all participants with oily skin (n = 793), tazarotene provided greater reductions in inflammatory/noninflammatory lesions (P < 0.001, both) and greater treatment success rates versus vehicle (P < 0.01) at week 12. Over two-thirds of polymeric lotion-treated participants had subjective skin oiliness reductions by week 12, with around a third reporting ‘low/not’ oily skin. Tazarotene TEAE rates were similar to the overall population. Conclusion Once-daily treatment with tazarotene 0.045% polymeric emulsion lotion may help improve patient-perceived skin oiliness in those with moderate-to-severe acne.
... Thinning of the SC is a common finding in photoaged skin, and it correlates with delayed skin barrier recovery, as seen in melasma [87]. This finding is contrary to expectations in darker skin phototypes, which exhibit better barrier recovery, thicker SC, and lower pH than fair skin [88]. ...
Article
Full-text available
Melasma is a multifactorial dyschromia that results from exposure to external factors (such as solar radiation) and hormonal factors (such as sex hormones and pregnancy), as well as skin inflammation (such as contact dermatitis and esthetic procedures), in genetically predisposed individuals. Beyond hyperfunctional melanocytes, skin with melasma exhibits a series of structural and functional alterations in the epidermis, basement membrane, and upper dermis that interact to elicit and sustain a focal hypermelanogenic phenotype. Evolution in the knowledge of the genetic basis of melasma and the cutaneous response to solar radiation, as well as the roles of endocrine factors, antioxidant system, endothelium proliferation, fibroblast senescence, mast cell degranulation, autophagy deficits of the melanocyte, and the paracrine regulation of melanogenesis, will lead to the development of new treatments and preventive strategies. This review presents current knowledge on these aspects of the pathogenesis of melasma and discusses the effects of specific treatments and future research on these issues.
... to regulate the transcription of the MITF gene [28,29]. We found 13 POU gene family members within the duck genome. ...
Article
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Background Skin pigmentation is a broadly appearing phenomenon of most animals and humans in nature. Here we used a bird model to investigate why melanin spot deposits on the skin. Results Our result showed that growth age and the sunlight might induce melanin deposition in bird beak skin which was determined by genetic factors. GWAS helped us to identify two major loci affecting melanin deposition, located on chromosomes 13 and 25, respectively. The fine mapping works narrowed the candidate regions to 0.98 Mb and 1.0 Mb on chromosomes 13 and 25. The MITF and POU2F3 may be the causative genes and synergistically affect melanin deposition during duck beak skin. Furthermore, our data strongly demonstrated that the pathway of melanin metabolism contributes to melanin deposition on the skin. Conclusions We demonstrated that age and sunlight induce melanin deposition in bird beak skin, while heredity is fundamental. The MITF and POU2F3 likely played a synergistic effect on the regulation of melanin synthesis, and their mutations contribute to phenotypic differences in beak melanin deposition among individuals. It is pointed out that melanin deposition in the skin is related to the pathway of melanin metabolism, which provided insights into the molecular regulatory mechanisms and the genetic improvement of the melanin deposition in duck beak.
... The skin is the largest organ of the body, comprising approximately 1.7 m 2 and accounting for approximately 10% of total body weight of an average adult [57,58]. Skin provides a physiological barrier to shield the body from external sources including ultraviolet radiation, allergens, microorganisms and chemicals [57,59,60]. ...
Article
The poor aqueous solubility of many approved drugs and most new chemical entities poses a challenge to drug delivery scientists working in academic and industrial labs. Despite the high pharmacological activity these drugs may have, their limited water solubility leads to poor absorption and consequently to sub-therapeutic drug concentrations in target tissues. The formulation of drug nanocrystals (NCs) has emerged as one the most promising approaches for increasing the biopharmaceutical performance of hydrophobic drugs. Initially aimed at increasing the absorption of drugs administered orally, NCs have been increasingly utilised to allow drug delivery via multiple routes, namely, parenteral injections, transdermal, ocular, intranasal, and pulmonary. This review aims to describe the recent progress in the field and demonstrate how the NCs technology enabled the delivery of hydrophobic drugs through multiple administration routes.
... These changes had a higher incidence in lighter coloured horses, which might be due to lightly pigmented skin/mucosa being weaker and less resistant to wear than darker skin/mucosa. In people, black skin has greater cohesiveness than lighter coloured skin under some circumstances, but is also more likely to show mottled hyperpigmentation with an uneven skin tone [11]. Thus, dark skin might have a protective effect against the development of wear and pathological changes but can more easily display pigment changes. ...
Article
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This study addresses the presence and location of natural pigmentation, potentially pathological changes in pigment, interruptions of the natural lining (scars), roughness, and erosions/contusion (bruising) in and around the corners of the lips of 206 horses presented to a veterinarian for routine preventative dental treatment. After sedation, photographs were taken and later evaluated for the presence of lesions. During the photographic analysis, the Oral Commissure Assessment (OCA) protocol was developed to map precisely the areas of skin and mucosa around the corners of the lips, and the presence of lesions was recorded for each area. Potentially pathological pigment changes occurred more frequently in horses with a higher level of training (p = 0.04) and in light-coloured horses (p = 0.0004), but there was no association with the current use of a bit or the discipline that the horse participated in (p = 0.20). Scars occurred more frequently in horses competing at a higher level. Only two horses had contusions or erosions, five had ulcers, and none showed bleeding; these numbers were too low for statistical analysis. Using the OCA protocol provides a detailed method for categorizing and recording lesions in and around the corners of the lips, including natural vs. potential and/or definite pathological character.
... Face alterations in different ethnic can describe genetic differences which show with face age progression also. Some face age-related factors such as the color of skin, skin thickness and natural moisturizer [8,9], etc. can be different from one ethic to another. Also, human skin is observed with many gender differences [10]. ...
Article
Recently, there is incredible progress in the arena of machine learning with generative adversarial network (GAN) methods. These methods tend to synthesize new data from input images that are highly realistic at the output. One of its applications in the image-to-image transformation way is the face aging task. In the face aging process, new face images are synthesized with the help of the input images and desired target images. Face aging can be beneficial in several domains such as in biometric systems for face recognition with age progression, in forensics for helping to find the missing children, in entertainment, and many more. Nowadays, several GANs are available for face aging applications and this paper focuses on the insight comparison among the frequently used image-to-image translation GANs which are CycleGAN (Cycle-Consistent Adversarial Network) and AttentionGAN (Attention-Guided Generative Adversarial Network). The first model (CycleGAN) comprises two generators, two discriminators, and converting an image from one domain to another without the need for paired images dataset. The second is AttentionGAN, which consists of attention masks and content masks multiplied with the generated output in one domain to generate a highly realistic image in another domain. For comparison, these two are trained on two dataset which is CelebA-HQ (CelebFaces Attributes high-quality dataset) and FFHQ (Flickr Faces HQ). Efficacy is evaluated quantitatively with identity preservation, five image quality assessment metrics, and qualitatively with a perceptual study on synthesized images, face aging signs, and robustness. It has been concluded that overall CycleGAN has better performance than AttentionGAN. In the future, a more critical comparison can be performed on the number of GANs for face aging applications.
... The molecular anatomy together with the cellular and lipid architecture of stratum corneum (SC) is now well established for healthy skin barrier function [1]. Ethnic differences in SC structure, biochemical composition and function were recently reviewed with the aim of identifying the need for ethnically targeted skin care solutions [2][3][4]. However, there are limited data on ethnic differences in facial skin, especially in relation to the biochemistry of the SC. ...
Article
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Introduction: We report on the differences in ceramide composition and levels of omega-O-acylceramide processing enzymes of sun-exposed and sun-protected facial stratum corneum (SC) among Albino African, Black African and Caucasian women living in South Africa. Methods: Tape strippings were taken from the sun-exposed cheek and the sun-protected postauricular site (PA). In two subsets proteomic (n=18) and lipidomic (n=24) analysis were performed using mass-spectrometry-based shotgun platforms. Results: No significant differences in total ceramide levels or ceramide subtypes were found between the Black African and Caucasian women in either the cheek or PA samples. Compared to the other two groups the levels of total ceramide as well as selected omega-O-acylceramide species were increased in Albino Africans. On the cheek, ceramide (CER) EOS, EOH along with CER AS were increased relative to the Caucasian women, while CER EOP and EOdS were elevated relative to the Black African women. Moreover, on the PA site CER EOP and EOdS were elevated compared with the Black African women and CER EOdS in Caucasians. Decreases in mass levels of 12R-LOX and eLOX3 were observed on cheeks compared with the PA sites in all ethnic groups. On the PA sites 12R-LOX was particularly lower in the Albino Africans compared with the Black African and Caucasian women. On the cheeks mass levels of SDR9C7 was also lower in the Albino Africans. Conclusion: The mass levels of the ceramides were similar between Black African and Caucasian women. However, elevated total ceramides and excessively elevated selected omega-O-acylceramides were apparent in the Albino African women. The findings in the Albino women were unexpected as these participants suffer from impaired skin barrier function. However, the elevated levels omega-O-acylceramides can contribute to barrier insufficiency by directly impacting SC lipid phase behaviour and/or secondly elevated omega-O-acylceramide levels may indicate a reduced attachment of ceramides to the corneocyte lipid envelope and reduced corneocyte maturation that can also impair the barrier. Indeed, differences in the mass levels of omega-O-acylceramide processing enzymes were observed for 12R-LOX and SDR9C7 for the Albino Africans. This indicates a corneocyte lipid scaffold disorder in the Albino African women.
... Researches into the principles of diversities in ageing process have identified intrinsic factors as being crucial to consider. In the following, some studies are described to To clarify the definition of the term ethnicity, we can mention that it refers to large groups of inhabitants who share a common language and culture, whereas race typically represents a distinct population in terms of genetic similarity [165]. In this section, we allude to ethnic skin as the wide scope of skin phenotypes and compositions that portray people with obscurely pigmented skin including African American, Asian, Caucasian and Latino/Hispanic ancestry. ...
Thesis
The aim of this thesis is to deploy and develop mathematical models to digitally simulate the human faces at any target age. The state-of-the-art in ageing modeling has not addressed the role of biological maturation from infancy to young adulthood where the anthropometrical displacements are occurring. In addition, the three dimensional (3D) face representation is considered in this thesis. The depth and pose variation provides additional information to represent faces accurately.Contrary to numerous studies that focused on 2D facial ageing and predicting the face appearance in the future, this thesis proposes the mathematical de-ageing and ageing models using 3D facial textured meshes of human faces considering the natural trajectory of ageing development during childhood, adulthood and senility.For the purpose of model construction, the face templates are reconstructed in 3D for the age groups from 3 to 75 years old for both genders.To validate the results, three metrics are defined to assess the faces from textural, geometrical and landmark distortion aspects. The metrics were applied on the collected database Face Time-Machine (FaceTim V.2.0) which contains the ground truth 3D faces. The results of the performance evaluation metric on the de-ageing model known as 3D B-FAM show the similarity rate of 75% which means the model does not represent significant disparity.Having considered that facial ageing phenomenon rely on various intrinsic and extrinsic circumstances, we propose a dynamic shape model as a fusion of de-ageing ageing models. This model takes into account the facial shape variations due to lifestyle and nutritious diet. The rendering results indicate that they are perceptually satisfying. Besides, the evaluation results show that the proposed models are remarkably accurate to predict the correct face appearance of an individual in the target age and shape.Furthermore, we address facial asymmetry for methamphetamine addicts using a collected drug-addicted face database. The facial asymmetry is assessed by employing the structural similarity index for textural aspect; and bilateral features for morphological quantification. Statistical analysis indicates a significant increment of facial asymmetry for methamphetamine addicts while ageing. The statistical analysis shows that for drug-addicts, the asymmetry measurement in faces before using drugs is 2% in geometry aspect and it reaches to more than 5%. This increment is seen in textural aspect where the similarity index is 28% and points to 39% for drug addicts.
... Only its variation can be relevant. Moreover, the age effect of the donor is consistent with the literature: the younger skin has an elastic modulus higher than the older ones, which implies a greater firmness of this skin (Rawlings, 2006). This is particularly significant by observing the structural parameter . ...
Article
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As an answer to alternative non-animal testing, biosensors dedicated to the ex vivo skin explants monitoring are a challenge to study physiological-like behavior and optimize new topical products. Because of the skin viscoelastic behavior, mechanical tests are commonly based on macroscopic measurement and give global descriptors of its state. Other techniques, including photoacoustic ones, are more focused on the molecular scale. There is a gap to fill in the mesoscopic range to get information about the microstructure of the skin. This article presents the proof-of-concept of a biosensor coupling a thickness shear-mode transducer with human skin explants kept in life-like state for a week. Thanks to a multifrequency analysis of the transducer impedance, this biosensor is able to monitor the viscoelastic properties of the skin. To extract the complex shear modulus and the microstructural evolutions, a mechanical model based on fractional calculus is used. As a preliminary results, the sensitivity of the sensor to probe the skin viscoelasticity in lifelike state and the impact of its culture medium are presented. A suitable microstructural coefficient is also extracted in order to identify mechanical breaches in the skin barrier after the application of peeling products.
... Variation in physiological variables with diet is also clearly visible from the results, with vegetarian subjects recording lower M r and H r . Studies [41,42] have postulated that the subcutaneous layer characteristics of subjects changes with their ethnicity. This change can affect the rate of heat dissipation from the body, resulting in heat gain variation. ...
Article
This paper estimates metabolic rate and physiological response associated with different activity intensities through controlled climate chamber experiments. We investigate the effect of activity intensity, personal and environmental factors on the subjects' heart rate, oxygen consumption, energy expenditure, and metabolic rate (Mr). Forty-eight adult Indian subjects categorized based on age, gender, Body Mass Index (BMI), ethnicity and dietary practices are subjected to different temperature, relative humidity, and air velocity set-points. Cardio-Pulmonary Exercise Test (CPET) and Resting Metabolic Rate (RMR) Test are performed in a climate camber based on appropriate experimental protocols. We find substantial variation in the physiological responses concerning activity intensity. The difference in Mr for different age and BMI groups is statistically significant. Mr of stationary activities exhibits marginal variation with temperature change. However, Mr of non-stationary activities shows significant variation with temperature variations. The effect of relative humidity on Mr is significant for non-stationary activities. Ethnicity and dietary habits of the subjects depict good relationship with the mean Mr for non-stationary activities. There is a significant difference observed in the metabolic stabilisation period for different age group categories in non-stationary activities. We present the impact of these intrinsic variations of Mr on thermal comfort estimations.
... Asian participants had the highest CER/cholesterol ratio, followed by Caucasian participants, and African participants had the lowest ratio. The amount of the total free extractable SC CERs in Negroid individuals was approximately 50% less than that observed in Caucasian and Hispanic individuals (Rawlings 2006). Imokawa et al. (Imokawa et al. 1991) have reported that the amount of total free extractable CERs in the human SC was significantly decreased with aging. ...
Article
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Ceramide (CER), an important component of the extracellular lamellar lipids in the stratum corneum (SC), plays a critical role in maintaining the cutaneous barrier function. This study aimed to determine whether the quantity of free extractable SC CERs in dogs was affected by the age, sex, or breed. Fifty-eight dogs from the breeds Shiba Inu, beagle, miniature dachshund, shih tzu, and golden retriever, without any history of skin problems, were enrolled in this study. Lipid extracts from the SC were subjected to high-performance thin-layer chromatography to quantify the free extractable CERs. There were weak negative correlations between the age and the amount of free extractable CERs, CER [NP] (non-hydroxy fatty acids linked to phytosphingosines), CER [AS/NH] (α-hydroxy fatty acids linked to sphingosines/non-hydroxy fatty acids linked to 6-hydroxysphingosines), and CER [AP] (α-hydroxy fatty acids and phytosphingosines). There were no significant sex- or breed-related differences in the amounts of free extractable SC CERs in the dogs. These findings imply that aging causes a decline in the amount of free extractable SC CERs in dogs, similar to that observed in humans. The sex or breed of the dogs investigated in this study did not influence the amount of free extractable SC CERs.
... Skin pigmentation plays a key role in determining its susceptibility to external insults, primarily exposure to ultraviolet radiation (UVR). 2 However, it further influences the prevalence of dermatological disease, such as the incidence of keloid scars 3 or keratinocyte carcinoma. 4 Despite differences in susceptibility to the development of skin disease, studies of human skinits anatomy, physiology or pathobiologyoften focus on lightly pigmented, white individuals of European heritage. Within dermatology, an appreciation of understanding skinin all of its diversityis now beginning to emerge. ...
... There have been some studies on the difference in skin characteristics between races [17]. Because of the nature of the scalp, mainly sebum-based racial comparison studies were performed. ...
... Because of the different light reflections and absorption caused by the mixture of these chromophores, the skin appears in various shades. The combination of oxyhemoglobin and hemoglobin developed a pink color in white skin and the interaction of melanin and carotenes to develop a yellow-orange color in brown skin [53]. Melanocytes are skin cells that produce the color melanin. ...
Article
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Background: In the world scientific tradition, skin color is the primary physical characteristic used to divide humans into groups. Human skin has a wide range of tones and colors, which can be seen in a wide range of demographic populations. Many factors influence the color of people's skin, but the pigment melanin is by far the most important. Melanin is produced by cells called melanocytes in the skin and is the primary determinant of skin color in people with darker skin. Indeed, >150 genes have now been identified as having a direct or indirect effect on skin color. Vitamin D has recently been discovered to regulate cellular proliferation and differentiation in a variety of tissues, including the skin. The mechanisms through which the active vitamin D metabolite 1,25 dihydroxyvitamin D3 (or calcitriol) affects keratinocyte development are numerous and overlap with the mechanisms by which calcium influences keratinocyte differentiation. Ultraviolet (UV) is the most major modifiable risk factor for skin cancer and many other environmental-influenced skin disorders when it is abundant in the environment. Although the UV component of sunlight is known to cause skin damage, few researches have looked at the impact of non-UV solar radiation on skin physiology in terms of inflammation, and there is less information on the role of visible light in pigmentation. Summary: The quantity and quality of melanin are regulating by the expression of genes. The enzyme tyrosinase is primarily responsible for the genetic mechanism that controls human skin color. Genetics determines constitutive skin color, which is reinforced by facultative melanogenesis and tanning reactions. High quantities of melanin and melanogenic substances are typically accepted in darker skin to protect against UV radiation-induced molecular damage. Previous research has proposed that skin color variation is caused by a dynamic genetic mechanism, contributing to our understanding of how population demographic history and natural selection shape human genetic and phenotypic diversity. However, the most significant ethnic skin color difference is determined by melanin content. This current review aimed to assess the influence of skin color variations in skin structure and functions as well as difference in dermatological disease patterns. Also, this article reviewed several cases of skin color adaptation in different populations. Key Messages: Skin color impacts the composition and activity. Therefore, the contrast of dermatological ailments between distinct race-related categories is remarkable. Skin color adaptation is a challenging procedure. Refinement of skin color is an age-old craving of humans with ever-evolving drifts.
... The variations in skin pigmentation are the results of adaptability to various geographical locations [24,30] . ...
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Background Skin pigmentation is a broadly appearing phenomenon of most animals and humans in nature. Here we used a bird model to investigate why melanin spot deposits on the skin. Results We result shown that melanin deposition in bird skin was induced by growth age and ultraviolet UV radiation and determined by genetic factors. GWAS helped us to identify two major loci affecting melanin deposition, located on chromosomes 13 and 25, respectively. Fine mapping works narrowed the candidate regions to 0.98 Mb and 1.0 Mb on chromosome 13 and 25, respectively. The MITF and POU2F3 may be the causative genes and synergistically affect melanin deposition during duck skin. Furthermore, our data strongly demonstrated that the pathway of melanin metabolism contributes to melanin deposition on the skin. Conclusions We demonstrated that age and UV radiation induce melanin deposition in bird skin, while heredity is the fundamental factor. The MITF and POU2F3 likely played a synergistic effect on the regulation of melanin synthesis, and their mutations contribute to phenotypic differences in beak melanin deposition among individuals. It is pointed out that melanin deposition in the skin is related to the pathway of melanin metabolism, which provided insights into the molecular regulatory mechanisms and the genetic improvement of the melanin deposition in duck beak.
... In the English literature, there are only a few studies comparing the response of Asian and Caucasian skin to sunlight. [27][28][29] The aim of the current study was to determine whether this outdoor method would be able to differentiate more subtle differences between photoprotection levels by introducing an intermediate level of SPF, comparing products labeled as SPF 15 (P3), 30 (P5), and 50 (P8), as measured by erythema and delayed pigmentation. A secondary aim was to explore whether differences in skin responses to solar exposure between Chinese and Caucasian subjects could be observed. ...
Article
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Background Currently, sunscreens’ sun protection factor (SPF) and ultraviolet (UV) A protection are tested separately under indoor conditions, without considering external conditions that may affect performance. Studies are often conducted in Caucasian individuals; other racial groups may respond differently. Methods An outdoor, double-blind, intra-individual study was performed in 63 healthy Chinese and Caucasian volunteers in Singapore. Subjects underwent one outdoor sun exposure lasting 2-3 hours. ISO reference products P3 (SPF 15), P5 (SPF 30) and P8 (SPF 50+) applied at 2 mg/cm² were compared against each other and against an untreated exposed area (positive control) and an unexposed area (negative control). Endpoints were investigator global assessment (IGA) of erythema at 24 hours, IGA of pigmentation at 1 week, and colorimetry (a*, L* and ITA) at 24 hours and 1 week. Results Clinical erythema and pigmentation scores were statistically significantly different among the three sunscreens, with the highest SPF product providing the highest protection, confirming the discriminatory capacity of the model used. Colorimetric assessment correlated well with clinical evaluation. Conclusion This study confirmed the feasibility of ranking sunscreens (at 2 mg/cm²) based on clinical effects of high-intensity outdoor solar radiation. Larger studies are needed to look at differences in erythema and pigmentation reactions between Chinese and Caucasian individuals, which could be relevant for photoprotection.
... Cu, copper; DDC, dopamine decarboxylase; Fe, iron; H 2 O 2 , hydrogen peroxide; O 2 , superoxide; OH, hydroxyl radical; SOD, superoxide dismutase; TH, tyrosine hydroxylase; TY, tyrosinase; Zn, zinc can produce more melanin when stimulated such as by UV radiation of sunlight, with response in South Asians four times greater than in white Caucasians. 29,30 The quickest appearance of vitiligo following nitisinone administration was in case 4 who received the larger dose of nitisinone, and also with the greatest increase in serum tyrosine. The final observation that only one of the four patients in this report was a woman, generally more prone to autoimmune disease, could be due to the beneficial effect of estrogen in directing the tyrosine pathway toward 4-hydroxyphenylpyruvate through stimulation of ratelimiting tyrosine aminotransferase. ...
Article
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Four patients, from three families, with alkaptonuria receiving 4-hydroxyphenylpyruvate dioxygenase-inhibiting nitisinone therapy, which lowers homogentisic acid and increases tyrosine, developed vitiligo. Three of the four patients were receiving nitisinone 2 mg daily, while the fourth was on 10 mg daily. All four patients were either receiving or had received transiently proton-pump inhibitors as therapy for dyspepsia. The ages of the patients were 35, 42, 40, and 67 years, respectively. Three patients were men and one was a woman. All four patients were either taking a proton-pump inhibitor or had been taking one at some point. Three of the four were of South Asian and one of Caucasian background. The three patients with South Asian background also had either a personal or family history of autoimmune disease. Distressing vitiligo, initially in an acrofacial distribution, developed unexpectedly in these four patients, before then progressing to involve other parts of the body. Potential factors in the appearance of vitiligo in this setting, including nitisinone and other drug therapy, are explored and responses to the appearance of vitiligo are discussed.
... The skin phototype (SPT) is a common classification system that categorizes the skin types of all people by correlating the skin color and its dynamic capability with UV light exposures [109]. In particular, the significant difference in skin color are attributed by UV exposure, genetics, as well as the size and distribution of melanosomes present in the skin [110,111]. ...
Article
Wound healing is an elaborated process, well-regulated via cell migration and proliferation. Although the physiological basics of wound healing have been thoroughly investigated and reported, much remain to be studied. Particularly, various studies have demonstrated the immunomodulatory roles of exosomes derived from plant cells, mammalian cells and mesenchymal stem cells (MSCs) in the healing and repair system. The paracrine and therapeutic effects of exosomes are mainly associated with the broad exosomal cargo content comprising of growth factors, cytokines, enzymes, nucleic acids, proteins and lipid signaling molecules. Nevertheless, functional or mechanism pathway of exosomes with reference to overall exosomal cargo remains undetermined. To date, combinatorial analysis strategies employing Database for Annotation, Visualization, and Integrated Discovery (DAVID), STRING tools, Gene Ontology (GO), Kyoto Encyclopedia of Genes, Genomes (KEGG) pathway enrichment analysis, as well as Ingenuity Pathway Analysis (IPA) have been applied in elucidating network interaction and functional pathway of exosomes. In this review paper, application of combinatorial analysis strategies is demonstrated to better understand on the therapeutic potentials of exosomes in wound healing process. In conclusion, functional modulation of exosomal cargo for specify biological treatment is achievable, modelling of combinatorial analysis strategies will hopefully bridge the research gap and provides a paradigm shift to regenerative processes.
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Objective: There are very few studies about total knee arthroplasty biomechanical and biochemical effects in the early postoperative period. The aim of this study was to investigate the effect of total knee arthroplasty on pain intensity, knee joint valgus angle, malalignment, functional status, knee joint position sense, and cytokine levels. Methods: A total of 29 patients (female/male: 24/5) who underwent total knee arthroplasty were included in the late-stage knee osteoarthritis group, and 22 patients (female/male: 13/9) with grade 4 osteoarthritis were included in the early-stage knee osteoarthritis group. The visual analog scale and the Western Ontario and McMaster Universities Osteoarthritis Index were used to evaluate the pain intensity and functional status. Alignment and knee position sense measurements were also calculated. Systemic venous blood samples were taken to evaluate the interleukin-6, tumor necrosis factor-alpha, and interleukin-1 beta cytokine levels. Results: In the study group, there were positive improvements in pain intensity, functional status, valgus angle, malalignment, amount of joint position sense deviation at 70° knee flexion angle parameters, and interleukin-6 of patients at the postoperative 6th week compared to the preoperative period (p<0.05). The patients in the study group had similar or better results in pain intensity, functional status, valgus angle, malalignment, amount of joint position sense deviation at 35°, 55°, and 70° knee flexion angles parameters, and in interleukin-6, compared to the control group at postoperative 6th week. Conclusion: Total knee arthroplasty provides improvements in pain, function, valgus angle, joint position sense, and interleukin-6 in the early postoperative period.
Article
Light beam propagation inside biological tissue, is crucial for many fields. Giving that, we had investigated the effect of melanin, on light propagation inside different type of tissue. We had constructed phantoms that approximates a real tissue and mimic its reaction to light. The skin model of seven layers takes into consideration the volume fractions and optical properties of blood, water, and melanin content. We developed a Monte Carlo simulation to investigate the intensity distribution inside tissues of a light beam. The study is done for different Fitzpatrick skin types. We provide the intensity distribution and the penetration depth in the 200–1000 nm wavelength range.
Chapter
Purpose: The United States will soon be a nation of color; however, much of our knowledge of normal skin disease and treatment thereof is based on white skin. We and others have attempted to elucidate any potential differences and advantages/disadvantages in skin function that have emerged during Homo sapiens evolution post major migration from Eastern Africa. We investigated differences in one stratum corneum function by examining transepidermal water loss (TEWL) measurements in skin of color compared to Caucasian skin. TEWL, a measure of insensible water loss through the stratum corneum, plays a major role in human survival. Materials and Methods: A comprehensive literature search was conducted to procure relevant papers that measured baseline TEWL in skin of color and Caucasian skin. Results: The data shows wide contradiction in results for all skin of color groups and white skin, and, therefore, no conclusion can be made based on this question. Conclusion: We suggest this variation may be due to experimental confounding variables that impact TEWL quantification, such as anatomic site and sample size—subject to further analysis and focus.KeywordsTransepidermal water lossSkin of colorRaceEthnicityStratum corneumSkin
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Purpose: Etonogestrel subdermal implants are a commonly used contraceptive device placed in the medial upper arm. Plastic and orthopedic surgeons may be consulted for difficult implant removals. We performed a case-control study comparing patients undergoing surgical and uncomplicated in-office removal at our institution. Patients and methods: We identified patients who underwent operative removal of implantable contraceptive devices by plastic or orthopedic surgeons at our institution from January 2014 to October 2019. Patients who underwent uncomplicated office removal during the same time were compared. Demographic and surgical variables were collected, and descriptive statistics were calculated. Univariate and multivariate logistic regression was performed with surgical versus outpatient removal as the outcome of interest. Results: A total of 669 patients undergoing etonogestrel subdermal implant removals were identified during the five-year study period, of which thirteen patients required surgical removal (1.9%) and 326 were selected as uncomplicated removal comparisons. There were no significant differences in median (IQR) body mass index (BMI) (31.1 [28.2, 35.2] versus 29.3 [24.0, 35.1], p = 0.19), median (IQR) weight gain since device placement (5 [-0.6, 14.7] kilograms versus 1.6 [-1.2, 5.8] kilograms, p = 0.15), or length of time since device insertion (2.3 [0.8, 2.8] years versus 1.0 [0.4, 2.2] years, p = 0.17). Of those who needed surgical removal, the most common indication for implant removal was device expiration (n = 5, 38.5%). Devices placed by OBGYN attendings were less likely to require surgical removal (p = 0.02). Family medicine attendings were more likely to refer patients for surgical removal (p = 0.02). No significant findings were detected on univariate or multivariate regression. Among surgical removals, radiography was the most frequently used imaging modality. Implants were most frequently subdermal (n = 11, 84.6%) though intramuscular placement was also identified (n = 2, 15.4%). Only one patient had residual paresthesia along the length of the incision. No other complications were identified. Conclusion: We did not identify risk factors associated with the difficult removal of etonogestrel subdermal implants. Practitioners should consult upper extremity surgeons if they encounter difficult removals.
Article
Detection and documentation of bruises on survivors of intimate partner violence (IPV) can provide valuable evidence to support investigation and subsequent prosecution of these crimes. Detection of bruises in persons with darker skin tones is often difficult, contributing to disparities in health and criminal justice responses to IPV. The purpose of this secondary data analysis was to determine whether use of an alternate light source (ALS) increased the predictive probability of successfully detecting bruises on diverse skin tones following a history of physical trauma. In this study, data were analyzed from a convenience sample of 157 subjects inclusive of six skin tones (very light, light, intermediate, tan, brown, dark) with induced bruises. Bruises were assessed under white light and an ALS 21 times over four weeks using 10 different ALS wavelength and goggle color combinations. Data analyzed included 31,841 skin observations obtained over 2897 participant assessments. Multilevel modeling was used to account for the correlation among the repeated measurements for each bruise. Across all categories of skin pigmentation, ALS wavelengths 415 nm and 450 nm viewed through a yellow filter had the most frequent detections of bruises (415 nm: n=2,777, 11.2%; 450 nm: n=2,747, 11.1%) and greater predictive probability of a positive finding (415 nm: 0.90-0.99; 450 nm: 0.85-0.99) than white light (n=2,487; 10%; 0.81-0.90). These two ALS wavelengths were the only combinations that provided greater probability of detection than white light on groups with darker skin (brown or dark), whereas additional ALS wavelengths/filters worked equally well on groups with lighter skin. Findings suggest use of an ALS in clinical assessments of patients of color who report IPV may help reduce health and criminal justice-related disparities.
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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.
Article
Objective: Ideal complexion is a perceptual skin quality that is strongly influenced by cultural and ethnic background. The objectives of this study are to quantitatively characterize skin ideal complexion based on clinical image cues and to compare the perceptions of ideal complexion among multiple ethnicities. Methods: Facial images of Indian, Chinese, Caucasian and Latino females collected using VISIA®-CR were presented to naïve panels of the same ethnicity following a two-alternative forced choice design and responses on skin "ideal complexion" were obtained from 336 panelists. Panel perception was transformed logistically (d') and projected onto a continuum (ω) following Bradley-Terry model. Image cues including skin color and unevenness, skin shine and surface smoothness, and pigmentary blotches and spots were computed using image analysis and their relationship with ω were evaluated through multiple regression analysis. A novel skin index namely ideal complexion score (ICS) was developed and correlated against age using linear regression. Finally, ICS was applied to evaluate treatment efficacy of a skin brightening kit on 35 female Caucasian subjects. Results: Panel perception d' showed statistically significant (p < 0.05) correlation with the contrast of image cues for all ethnic panels (R2 = 0.74, 0.76, 0.62 and 0.46 for Indian, Chinese, Caucasian and Latino respectively) and strong correlations between perception ω and linear combinations of image cues were observed (R2 > 0.88 for all). Main effects of facial image visual cues on ideal complexion were compared: contrast of skin redness and pigmented spots and visual smoothness were important in determining ICS for all ethnicities; skin color unevenness was more pronounced for Indian and Caucasian; skin lightness was important for Indian and Chinese; skin shine was critical for Chinese and Latino; and skin hue angle ranked higher for Caucasian. Correlations between ICS and age were observed for Indian and Caucasian (R2 = 0.55) in which ICS decreased as age increased. Twenty-nine percent improvement on ICS was observed after 12 weeks' treatment using the brightening kit compared to the baseline. Conclusion: Mathematical models were successfully established to describe subjective perception towards skin ideal complexion based on objectively measured image cues for multiple ethnicities.
Article
Skin of color (SOC) populations include those who identify as Black/African, Hispanic/Latinx, Asian/Pacific Islander, American Indian/Native Alaskan, Indigenous Australian, Middle Eastern, biracial/multiracial, or non-White; this list is far from exhaustive and may vary between and within cultures. Recent genetic and immunological studies have suggested that cutaneous inflammatory disorders (atopic dermatitis, psoriasis, and hidradenitis suppurativa) and malignancies (melanoma, basal cell carcinoma, and cutaneous T-cell lymphoma) may have variations in their immunophenotype among SOC. Additionally, there is growing recognition of the substantial role social determinants of health play in driving health inequalities in SOC communities. It is critically important to understand that social determinants of health often play a larger role than biological or genetic factors attributed to "race" in healthcare outcomes. Herein, we describe the structural, genetic, and immunological variations and the potential implications of these variations in populations with SOC. This article underscores the importance of increasing the number of large, robust genetic studies of cutaneous disorders in SOC to create more targeted, effective therapies for this often underserved and understudied population. Part II of this CME will highlight the clinical differences in the phenotypic presentation of and the health disparities associated with the aforementioned cutaneous disorders in SOC.
Article
Background/Purpose High-dose-rate (HDR) electronic brachytherapy (EBT) has been shown to be effective for non-melanoma skin cancer (NMSC) in Caucasian patients. However, its efficacy remains unknown in Asian patients. To analyze the clinical outcome of HDR EBT for NMSC in a Taiwanese medical center. Methods Medical records over a 5-year period between January 2015 to December 2019 were retrospectively analyzed. Results Forty-seven patients with 54 NMSC including 42 basal cell carcinomas (BCCs) and 12 squamous cell carcinomas (SCCs) were treated with HDR EBT. The average age was 73.8 years. The mean radiation dose was 45.3 Gy (40–80 Gy). Mean follow-up duration was 33.1 months. Adequate local control was achieved in 50 lesions (92.6%). Grade 1 acute skin toxicity was noted in 63.0% of lesions, while no tumors had Grade 4 acute toxicity. No ulceration was observed six months after completion of treatment. At the last follow-up visit, all lesions were rated to have “fair” to “excellent” cosmetic outcomes. Conclusion HDR EBT provides adequate clinical outcomes and cosmetic results for NMSC in Asian patients. Further investigation of the dosage guidelines is needed for Asian patients with NMSC.
Article
Despite cosmetic procedures being on the rise in the US in all demographics, cosmetic procedures remain heavily skewed towards non‐skin of color patients. Cosmetic clinical trials in the United States must be representative of the ever‐increasing diversity of the US population. We sought to analyze published cosmetic randomized controlled trials, both industry‐sponsored and investigator‐initiated, to characterize and assess representation of skin of color participants over the past three decades. Our study shows that industry sponsorship correlates with poor study participant ethnic/racial diversity in aesthetic randomized controlled trials, and should serve as a call to action for industries to increase the inclusion of skin of color participants in their studies.
Article
The imagery of pigmented skin is underrepresented in teaching materials such as textbooks, journals, and online references, and this has resulted in poorer diagnostic and management outcomes of skin pathology, including delayed cutaneous drug hypersensitivity reactions. In this review, we use clinical images to highlight factors that impact clinical presentations and sequelae of drug hypersensitivity reactions in pigmented skin compared with nonpigmented skin. We describe clinical features in some anatomic sites that aid diagnosis or are associated with more severe sequelae. Finally, we discuss strategies that may aid the diagnosis and management of these reactions in pigmented skin.
Chapter
Pigmentation is especially important in patients of skin of color because pigmentary disorder is the most common reason for a visit to a dermatologist in this group. Melanin, the major determinant of skin color, absorbs UV light and blocks free radical generation, protecting the skin from sun damage and aging. The melanocytes in black skin are larger, more active in making melanin, and the melanosomes are packaged, distributed, and broken down differently than in white skin. Melanosome pH is another factor that plays a role in regulating differences in skin color. In the skin, protease‐activated receptor 2 is expressed in the keratinocytes of the basal, spinous, and granular layers of the epidermis, endothelial cells, hair follicles, myoepithelial cells of sweat glands, and dermal dendritic‐like cells. The morphologic features of African hair were examined using the transmission and scanning electron microscopic techniques in an unpublished study.
Chapter
Regardless of ethnicity and gender, facial ageing is a multidimensional and multifactorial process involving all facial layers, including the skull, musculature, fat pads and cutaneous tissue. Ethnic differences in age-related facial changes are not fully established. The key studies examining age-related changes of the facial skeleton and soft tissue are done on Caucasians. There are distinct differences in facial structure and characteristics of Asians and Caucasians, and this is true for the ageing process too. Varied facial structures, genetics, environmental factors and lifestyle, including eating habits, skincare, and attention to beauty since early years, and sun avoidance altogether result in different facial ageing patterns of Asians compared to Caucasians. In East Asians, the midface usually has minimal rhytids, and mid-moderate ptosis is seen with ageing. Increased superficial fat in combination with thickened dermis reduces the prevalence of superficial rhytids. Furthermore, there is dense fat and fibrous connections between the superficial musculoaponeurotic system and parotideomasseteric fascia which reduce the amount of soft tissue ptosis in Asians. In East Asians, skin pigmentation is an early sign of ageing in comparison to periorbital and perioral rhytids in Caucasians.
Article
Background Despite the invention of various noninvasive bioengineering tools, skin-type analysis has largely been based on subjective assessments. However, advancements in the functional cosmetic industry and in artificial intelligence-assisted dermatology are creating a greater demand for an objective skin-type classification system. Objectives To propose an objective skin-type classification system solely based on noninvasive, bioengineering devices; provide reference values applicable to the Korean population; and compare our reference values with those of published studies. Methods Biophysical parameter measurements were obtained from the 2018 International Skin Characteristics Data Bank Project conducted by the Foundation of Korea Cosmetic Industry Institute. The participants were 434 healthy South Korean adults. Each participant was assessed using eight bioengineering devices (Tewameter®, pH-meter®, Corneometer®, Sebumeter®, Cutometer®, Spectrophotometer®, PRIMOS® lite, and Janus®). The measurements were divided into tertiles to determine reference points. Results Our objective skin-type classification consists of five main categories (sensitivity, hydration, oiliness, elasticity, and skin tone) and five corresponding subcategories (erythema, roughness, pores, wrinkles, and pigmentation, respectively). Each skin type was assigned based on the reference point of the biophysical parameter, which was established as the tertile value associated with ‘unfavorable’ skin characteristics. Individuals were categorized as having sensitive skin when the TEWL scores were over 18.0 g/m²/h or the pH was over 5.45; dehydrated skin when the corneometric value measured below 47.17 A.U.; oily skin when the sebumetric value exceeded 70 μg/cm²; and loose skin when the cutometric R2 value was below 0.68 E/mm. Conclusions This study is the first to provide a comprehensive skin-type classification system based solely on noninvasive biophysical parameters. As measurement data accumulates, the reference points will progress to become more accurate, and they will be subdivided according to gender, age, and ethnic group. Therefore, our classification system serves as a basis for artificial intelligence-based skin-type analysis.
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The persistence of traditional tattoo inks presents an advantage for continuous and long‐term health monitoring in point of care devices. The replacement of tattoo pigments with optical biosensors aims a promising alternative for monitoring blood biomarkers. Tattoo inks functionalization enables the control of interstitial biomarkers with correlated concentrations in plasma, to diagnose diseases, evaluate progression, and prevent complications associated with physio pathological disorders or medication mismatches. The specific biomarkers in interstitial fluid provide a new source of information, especially for skin diseases. The study of tattoo inks displays insufficient regulation in their composition, a lack of reports of the related complications, and a need for further studies on their degradation kinetics. This review focuses on tattoo optical biosensors for monitoring dermal interstitial biomarkers and discusses the clinical advantages and main challenges for in vivo implantation. Tattoo functionalization provides a minimally invasive, reversible, biocompatible, real‐time sensing with long‐term permanence and multiplexing capabilities for the control, diagnosis, and prevention of illness; it enables self‐controlling management by the patient, but also the possibility of sending the records to the doctor. The replacement of tattoo pigments with optical biosensors enables a minimally invasive, reversible, biocompatible, and real‐time platform with long‐term permanence and multiplexing capabilities for the control, diagnosis, and prevention of illness by monitoring interstitial biomarkers with correlated concentrations in plasma. The interaction of the biomarker with the biosensor produces a signal proportional to the biomarker concentration in the interstitial fluid.
Chapter
The desire to optimise one’s appearance is probably as old as mankind itself. In order to apply the artistic flourish of such a precise chemical tool as BoNT on the infinite variation of human anatomy some basic influences, both biological and fashion, are presented. Important contributors to aging are introduced.
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Introduction: Travelers may transmit diseases due to their behavior of travel, consequently travelers should consider preventive measurement through pre-travel health consultation seeking behavior. Pre-travel health consultation is a particular preparation ideally conducted by international travelers to obtain risk assessment and management to prevent the transmission of diseases. This study investigates the relationship of socio-demographic characteristics and itinerary on pre-travel health consultation behavior among international travelers in Badung, Bali.Methods: A descriptive-correlative design using a cross-sectional approach employed 125 participants determined by a purposive sampling technique performed in the ten tourist destinations of Badung Regency. Data collection was conducted on February 15th until March 5th, 2020. Data demography, travel plan, and anonymous questionnaires regarding pre-travel health consultation behavior are used in this research. The Gamma coefficient correlation and Kruskal-Wallis statistic tests were performed in the study for bivariate analysis.Results: The results showed that age (p<0.0001; r=-0.650) and past-travel history to Bali (p=0.004; r=-0.475) were significantly correlated with pre-travel health consultation behavior among international travelers in Badung, Bali. Meanwhile sex, nationality, last education, travel duration, and types of the destination visited were not significantly associated with pre-travel health consultation behavior among international travelers in Badung, Bali (p>0.05).Conclusion: The age and past-travel history to Bali seem to be predictors for travelers to uptake pre-travel health consultation, thus nurses should be able to promote the implementation of pre-travel health consultation by utilizing the media promotion appropriately adjusted to the age of travelers and travel experience.
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The most important function of the stratum corneum (SC), the uppermost layer of the human epidermis, is the formation of the epidermal permeability barrier. Lipids, particularly ceramides, cholesterol, and free fatty acids, together form lamellar membranes in the extracellular spaces of the SC that limit the loss of water and electrolytes. In addition to preventing water and electrolyte loss, the SC as a permeability barrier prevents the entry of harmful irritants, allergens, and microorganisms into the skin. Disruption of the epidermal barrier leads to skin that is irritated, more reactive, and more sensitive than normal skin. SC thickness, lipid profile, and barrier function vary with different ethnic groups, which is also reflected the differences in prevalence and manifestation of diverse skin conditions related to the skin barrier function such as atopic dermatitis and sensitive skin. In addition to these compromised skin barrier related conditions, we are just now starting to understand the direct and indirect impact of COVID-19 on the skin and how current preventative measures are contributing to skin barrier disorders. Our understanding of various approaches for restoration of skin barrier, especially the role of topically applied mixtures of cholesterol, ceramides, and essential/nonessential free fatty acids (FFAs) allows for the strengthening of the compromised skin barrier and alleviation of symptoms and discomfort associated with skin barrier disorders. Ceramide containing products on the market are commonly available and offer protection and reparative benefits to the skin barrier. J Drugs Dermatol. 20(4 Suppl):17-22. doi:10.36849/JDD.S589C.
Article
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.
Article
Background It is commonly believed that there is serious heterogeneity in the rate of wrinkle progression among individuals. Although several skin characteristics have been shown to influence wrinkle progression, the ability to predict which individuals with skin characteristics are likely to develop wrinkles is still limited. Objectives The purpose of this study is to develop and validate an effective prediction model for longitudinal changes in wrinkles. Methods We collected annual wrinkle scores and multiple skin physiological characteristics in 48 Japanese women over a period of 7 years. We developed a multivariable prediction model for predicting future wrinkle status based on the various skin physiological characteristics using a linear mixed‐effects model. Results After variable selection by backwards, the final wrinkle prediction model included age, sebum volume, redness of skin color, lightness of skin color, and an interaction term between sebum volume and redness of skin color. The developed prediction model showed favorable prediction accuracy (R² = 87.92%, 95% confidence interval 84.27%‐90.68%). Conclusions The developed model accurately predicted levels of wrinkles in Japanese women aged 22‐60 years. The prediction model is based on age and three practical skin characteristics, which might implicate an essential insight to prevent wrinkle progression in individuals.
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The skin pigment melanin is produced in melanocytes in highly specialized organelles known as melanosomes. Melanosomes are related to the organelles of the endosomal/lysosomal pathway and can have a low internal pH. In the present study we have shown that melanin synthesis in human pigment cell lysates is maximal at pH 6.8. We therefore investigated the role of intramelanosomal pH as a possible control mechanism for melanogenesis. To do this we examined the effect of neutralizing melanosomal pH on tyrosinase activity and melanogenesis in 11 human melanocyte cultures and in 3 melanoma lines. All melanocyte cultures (9 of 9) from Caucasian skin as well as two melanomacell lines with comparable melanogenic activity showed rapid (within 24 h) increases in melanogenesis in response to neutralization of melanosomal pH. Chemical analysis of total melanin indicated a preferential increase in eumelanin production. Electron microscopy revealed an accumulation of melanin and increased maturation of melanosomes in response to pH neutralization. In summary, our findings show that: (i) near neutral melanosomal pH is optimal for human tyrosinase activity and melanogenesis; (ii) melanin production in Caucasian melanocytes is suppressed by low melanosomal pH; (iii) the ratio of eumelanin/phaeomelanin production and maturation rate of melanosomes can be regulated by melanosomal pH. We conclude that melanosomal pH is an essential factor which regulates multiple stages of melanin production. Furthermore, since we have recently identified that pink locus product (P protein) mediates neutralization of melanosomal pH, we propose that P protein is a key control point for skin pigmentation. We would further propose that the wide variations in both constitutive and facultative skin pigmentation seen in the human population could be associated with the high degree of P-locus polymorphism.
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Human skin is continuously exposed to internal and external influences that may alter its condition and functioning. As a consequence, the skin may undergo alterations leading to photoaging, inflammation, immune dysfunction, imbalanced epidermal homeostasis, or other skin disorders. Modern nutritional science is developing new insights into the relation between food intake and health, and effects of food ingredients may prove to be biologically relevant for optimal skin condition. The objective of this review was to evaluate the present knowledge about the interrelation of nutrients and skin, particularly the photoprotective effects of nutrients, the influences of nutrients on cutaneous immune responses, and therapeutic actions of nutrients in skin disorders. The nutrients of focus were vitamins, carotenoids, and polyunsaturated fatty acids. Supplementation with these nutrients was shown to provide protection against ultraviolet light, although the sun-protection factor was relatively small compared with that of topical sunscreens. An increase in delayed-type hypersensitivity skin responses after supplementation with nutrients has proven beneficial, especially in elderly people, and may boost cell-mediated immunity. Dietary consumption of certain plants or fish oil is known to modulate the balance of lipid inflammatory mediators and, therefore, is valuable in the treatment of inflammatory skin disorders. It was concluded that nutritional factors exert promising actions on the skin, but information on the effects of low-to-moderate doses of nutrients consumed long term by healthy individuals is obviously lacking, as are data on direct effects on basal skin properties, including hydration, sebum production, and elasticity.
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Biologic rhythms of cells and organisms are well documented and have been extensively studied at the physiologic and molecular levels. For the skin, many circadian changes have been investigated but few systematic studies comparing skin at different body sites have been reported. In this study we investigated facial and forearm skin circadian rhythms in eight healthy Caucasian women. Noninvasive methods were used to assess skin capacitance, sebum excretion, skin temperature, transepidermal water loss, and skin surface pH on fixed sites of the face and the volar forearm during a 48 h span under standardized environmental conditions. Using the cosinor or ANOVA methods, circadian rhythms could be detected for sebum excretion (face), transepidermal water loss (face and forearm), skin temperature (forearm), pH (face), and capacitance (forearm). No circadian rhythmicity was found for the other biophysical parameters. In addition to the 24 h rhythm component, rhythms with periods of 8 h were found for sebum excretion, of 8 and 12 h for transepidermal water loss (face and forearm), and of 12 h for skin temperature (forearm). Our study confirms that rhythms of skin surface parameters are readily measurable and that these rhythms differ between different sites. Furthermore, we demonstrate for the first time that, for transepidermal water loss (face and forearm), sebum excretion, and skin temperature (forearm), in addition to circadian rhythms, ultradian and/or component rhythms can be detected.
Article
Background and Design: Previous studies that compared transepidermal water loss in subjects of different race and sex showed minimal differences in basal permeability barrier function. These studies often did not assess the ability of the stratum corneum to withstand or recover from insults to the epidermal permeability barrier. We compared epidermal permeability barrier function in the following human subjects (age range, 22 to 38 years): white (n=8) vs Asian (n=6); male (n=7) vs female (n=7); and skin type II/III (n=14) vs skin type V/VI (n=7) (scale, I to VI). Basal transepidermal water loss was measured by evaporimetry (three sites) on the volar aspect of the forearm. Barrier integrity then was assessed by determining the number of tape strippings required to reach a transepidermal water loss greater than or equal to 20 g/m2 per hour. The rates of barrier recovery then were compared at 6, 24, and 48 hours and 1 week after abrogation.Results: Neither the number of tape strippings required to perturb the barrier nor the rates of barrier recovery were significantly different in white vs Asian subjects or in female vs male subjects. However, patients with skin types II/III re- quired only 29.6±2.4 tape strippings to perturb the barrier, while the skin type V/VI group required 66.7±6.9 tape strippings. Furthermore, while barrier function in skin type II/ III recovered by approximately 20% by 6 hours and 55% by 48 hours, barrier function in skin type V/VI, independent of race, recovered more quickly, 43% and 72% at 6 and 48 hours, respectively. Finally, neither the differences in barrier integrity nor in rates of recovery could be attributed to variations in cohesiveness, since stripping appears to remove the same weight of stratum corneum in both groups.Conclusions: Darkly pigmented skin displays both a more resistant barrier and one that recovers more quickly after perturbation by tape stripping than does the skin of individuals with lighter pigmentation. These findings have potential implications for transdermal delivery of topical or systemic therapeutic agents, the ability of individuals with different skin types to withstand environmental or occupational insults, and the influence of acquired hyperpigmentation or pigment loss to influence permeability.(Arch Dermatol. 1995;131:1134-1138)
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敏感肌に関する意識は国内外問わず高く, 自分の肌が敏感だと思う女性は増加の一途をたどっている。簡単で的確に敏感の程度を評価できる方法があれば, 敏感肌に効果的な化粧料を提供するために非常に有用である。われわれは敏感肌を推定する方法を試みるにあたり, 女性が自分の肌をどのように感じたとき敏感肌であると思っているかを調査した。その結果, 多様な理由があげられた一方で, 概ね共通の症状として痒み, 赤み, カサツキが認められることがわかった。これらの発症には角層のバリア機能の低下が考えられたことから, われわれは角層細胞に着目し, その形態学的な計測から敏感肌を推定する方法を試みた。研究の指標としてδAPAc (テープストリッピングにより採取した角層細胞の面積の同季節における同年齢の平均値からの偏差) に着目し敏感肌と健常肌とを比較した。この結果から, 角層細胞面積と敏感の程度には関連性があり, 面積を測定することにより, 肌の敏感の程度を従来の方法より正確に把握することが可能であることが示された。さらに本法を用いることにより皮膚特性に合わせた化粧料を提供することが可能になるものと考えられた。
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We report the utility of photographic scales to assess the degree of human facial wrinkles. A five-grade photo scale of wrinkles at eye corners was developed using photos obtained from 411 female participants aged 17 to 83 years. Based on this photo scale, scorings (five grades and nine grades) of all photos were performed by two specialists, and a standard photo for each wrinkle grade was obtained. In addition, in order to evaluate the influence of inter-observer differences in grading criteria, another scoring was performed by five general observers. The agreement between the grade standard and the score given by the general observers was evaluated by calculating the chance-corrected coefficient, i.e., the kappa value. The degree of agreement for the five-grade scale was more consistent than that for the nine-grade scale system, in which the kappa values were 0.499 and 0.396, respectively. When scoring was performed using the five-grade photo scale for the eye corners after 15 participants used a wrinkle-improving agent, a significant reduction of the wrinkle scores was confirmed. Taken together, the present findings indicate that the five-grade wrinkle photo scale is valid and useful to assess the degree of facial wrinkles.
Article
Differences in the characteristics of black and white skin were investigated in thirty black and thirty white female subjects between the ages of 18 and 45, using noninvasive methods. Parameters studied included transepidermal water loss (TEWL), electrical capacitance, skin pH, elasticity, dryness/scaling, and skin surface microflora. TEWL was found to be significantly lower on the cheeks and legs in blacks as compared to whites. Black facial skin exhibited higher elasticity and electrical capacitance values. The desquamation index was found to be higher in white subjects on the cheeks and forehead, whereas dryness scores were significantly higher for blacks on the legs. Whites had slightly higher pH than blacks. Overall density of Propionibacterium acnes was found to be higher in blacks. No significant differences were found in the aerobic skin surface microflora. Results from the present study will help gain a better understanding of the variations in characteristics of black and white skin.
Article
The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
Article
in the lower stratum comeurn but underwent degradation towards the upper surface of the stratum corneum. These observations contrasted with xerotic skin, which had disorganized lipid bilayers in the upper stratum corneum, although apparently normal lipid bilayers in the deeper tissue regions. Also, desmosomes remained undegraded in the upper layers of the xerotic stratum corneum, a finding corrobo- rated by western blotting showing increased levels of desmoglein 1. Chromatographic analysis of stratum comeurn lipids showed decreased ceramide and increased fatty acid levels in subjects with xerosis compared with normal individuals, particularly in the outer stratum corneum layers. Although ceramides were lost from the stratum comeurn, the increased levels of fatty acids may be due in part to the deposition of soap fatty acids. Our results support previous studies demonstrating the importance of desmosomal degradation in desquamation. Furthermore, we have been able to show changes in the normal membrane structure of intracellular lipids in the desquamating layers of the stratum comeurn. These studies also provide new insights into soap-induced winter xerosis, revealing abnormalities in stratum comeurn lipid composition and organization together with reduced desmosomal degradation.
Article
The purpose of this study was to determine whether a significant difference exists between Negroes and Caucasians in cutaneous irritant reaction to CS, and to try to localize to a specific layer of skin any relative protective principle which Negro skin might have. A determination as to whether racial difference exists in the symptomatic response of the skin was also sought. Standardized exposures were given on the volar surface of the forearm and the back by an occlusive patch-test technique, utilizing duration of exposure as the variable. A range of exposures, low to high, was given each subject, and the minimal perceptible erythema (MPE) was read. The impression that Negroes are less susceptible to irritant determatitis from CS2 was confirmed. On both forearm and back, the production of MPE required approximately twice the exposure time on Negroes as on Caucasians. The racial difference in reactivity is lost if stratum corneum (the barrier layer) is removed. Neither is there a racial difference in the stinging sensation, which is caused by CS that penetrates by the transappendageal route. It is proposed that the difference in the melanin content of the stratum corneum between the two races may account for the difference in reactivity; i.e., that melanin exerts a protective influence, possibly by reacting with CS. (Author)
Article
Stratum corneum from Negroes and Caucasians has been compared with respect to facility of tape stripping, numbers of cell layers, and density. Significantly more strips were required for removal of stratum corneum, and significantly more cell layers were present in the stratum corneum from Negroes as compared to Caucasians. The buoyant density of abdominal stratum corneum, as determined in organic solvent systems, is less in Negroes than in Caucasians. The reverse is true when density in air is determined and when isopyknic sucrose density gradient ultracentrifugation is employed. We believe the latter values portray the true relationship of Negro and Caucasian stratum corneum, since detipidization does not occur, and since a greater density of Negro stratum corneum is consonant with its greater microscopic compactness.
Article
Sunlight is essential for human life but we need to avoid overexposure to the sun. Chronic exposure of the skin to UV radiation leads to photoageing (sunburn, wrinkles, spots, freckles, skin texture changes, and dilated blood vessels), immunosuppression, and sometime more serious lesions. UV radiation also causes DNA damage, which is a critical event in skin photoageing and photocarcinogenesis [1]. Exposure to UV light induces wide range of DNA lesions on skin cells by direct absorption (UVB), or via oxidative stress (UVA and UVB). We choose to work on healthy Chinese women skin because it is demonstrated that Asian people developed less skin cancer than Caucasian, and few studies have been done on DNA damage in the skin of Asian subjects [2, 3].
Article
The significance of our understanding of the chemistry of melanin and melanogenesis is reviewed. Melanogenesis begins with the production of dopaquinone, a highly reactive o-quinone. Pulse radiolysis is a powerful tool to study the fates of such highly reactive melanin precursors. Based on pulse radiolysis data reported by Land et al. (J Photochem Photobiol B: Biol 2001;64:123) and our biochemical studies, a pathway for mixed melanogenesis is proposed. Melanogenesis proceeds in three distinctive steps. The initial step is the production of cysteinyldopas by the rapid addition of cysteine to dopaquinone, which continues as long as cysteine is present (1 μM). The second step is the oxidation of cysteinyldopas to give pheomelanin, which continues as long as cysteinyldopas are present (10 μM). The last step is the production of eumelanin, which begins only after most cysteinyldopas are depleted. It thus appears that eumelanin is deposited on the preformed pheomelanin and that the ratio of eu- to pheomelanin is determined by the tyrosinase activity and cysteine concentration. In eumelanogenesis, dopachrome is a rather stable molecule and spontaneously decomposes to give mostly 5,6-dihydroxyindole. Dopachrome tautomerase (Dct) catalyses the tautomerization of dopachrome to give mostly 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Our study confirmed that the role of Dct is to increase the ratio of DHICA in eumelanin and to increase the production of eumelanin. In addition, the cytotoxicity of o-quinone melanin precursors was found to correlate with binding to proteins through the cysteine residues. Finally, it is still unknown how the availability of cysteine is controlled within the melanosome.
Article
Background There are conflicting reports of structural differences between black and white skin, other than pigmentary differences. Objectives To evaluate differences in mast cells between black and white skin. Methods Biopsies of normal buttock skin were obtained from four African-American males (29·2 ± 3·0 years old) and four Caucasian males (29·4 ± 1·2 years old) and processed routinely for electron microscopy. For the quantitative assessment of mast cell granules, five electron micrographs at a final magnification of × 53,700 were analysed for each individual, using a computer-assisted image analyser. More than 10 granules per cell, and a total of 1210 granules, were evaluated for their internal structures. Results Mast cells in black skin contained larger granules than those in white skin (P < 0·0001). In black skin, fusion of granules seemed to account for the larger sizes. The percentage of granule matrix occupied by curved lamellae was higher in white skin, whereas parallel–linear striations were more frequent in black skin (P < 0·05). The subgranular distribution of the mast cell proteases, tryptase and cathepsin G, were evaluated by immunoelectron microscopy. Tryptase reactivity was localized preferentially over the parallel–linear striations and partially over the dark amorphous subregions within granules of black skin, whereas it was confined to the peripheral area of granules, including curved lamellae, in white skin. Cathepsin G reactivity was more intense over the electron-dense amorphous areas in both groups, while parallel–linear striations in black skin and curved lamellae in white skin were negative. Conclusions This study has confirmed ultrastructural differences in mast cell granules between black and white skin, which may be of functional importance.
Article
The photoprotective role of melanin was evaluated by comparing the transmission of ultraviolet (UV) radiation through skin samples of blacks and Caucasians, using both biologic and spectroscopic techniques. UVA transmission was measured using fluoranthene, which causes a phototoxic response to UVA wavelength. UVB was measured by monitoring erythema produced by either a 150-watt xenon arc or FS-20 sunlamps. It was found that on the average, five times as much ultraviolet light (UVB and UVA) reaches the upper dermis of Caucasians as reaches that of blacks. Differences in transmission between the stratum corneum of blacks and of Caucasians were far less striking. The main site of UV filtration in Caucasians is the stratum corneum, whereas in blacks it is the malpighian layers. Melanin acts as a neutral density filter, reducing all wavelengths of light equally. The superior photoprotection of black epidermis is due not only to increased melanin content but also to other factors related to packaging and distribution of melanosomes. Not only are these data consistent with epidemiologic evidence, but they also may indicate why blacks are less disposed to phototoxic drug responses as well as less susceptible to acute and chronic actinic damage.
Article
The assessment of the severity of cutaneous photodamage and its response to treatment is an impractical consideration for most practitioners without extensive experience or recourse to high-quality, standardized, baseline photographs. To address this problem, a nine-point photonumeric standard scale was developed using photographs of subjects representing grades of photodamage from none to severe. This scale was formally tested in a side-by-side comparison with a conventional and widely used written descriptive scale. A panel of seven graders used both scales to score two sets of 25 photographs of photodamaged individuals, and the intergrader agreement and repeatability for the scales were calculated. The photonumeric scale demonstrated significantly greater agreement between graders than did the descriptive scale (chance-corrected agreements of 0.31 and 0.11, respectively, P less than .0001) with no significant difference in repeatability between the two methods. This study demonstrates that the photonumeric standard scale is superior to existing methodology in the accurate assessment of cutaneous photodamage and would be a useful adjunct to studies of the efficacy of skin repair agents for this indication.
Article
It is well known that spontaneous desquamation and corneocyte size can reflect respectively stratum corneum cohesiveness and epidermal cell proliferation. The influence of skin pigmentation on these parameters has been investigated on the upper-outer arm of black, white and oriental volunteers, using the detergent scrub method. We found no difference between race in corneocyte surface area, a mean size of 900 microns 2 agreeing closely with that generally encountered in Whites on the upper-outer arm. By contrast, spontaneous desquamation is increased in black vis-à-vis white and oriental skin (factor 2.5, p less than 0.001). Taking into account the importance of the intercellular cement for the cohesion between corneocytes, racial differences in epidermal lipid composition should be investigated.
Article
The role of race in modulating skin responses has been investigated. Several parameters (skin thickness, transepidermal water loss, water content of the stratum corneum and skin biomechanics) have been measured using noninvasive tools in whites, Hispanics and blacks to assess whether the melanin content could induce changes in skin biophysical properties. Marked differences between races appear in stratum corneum water content and in skin extensibility, recovery and elastic modulus. Measurements done in different sun-exposed sites highlight the effects of solar irradiation on the skin and the role of melanin in preventing skin damage. The study shows that racial differences in skin physiology exist and are mainly related to the protective role of melanin present in races with darker skin. Moreover, differences in skin hydration are not fully explained according to the site and presence of hair.
Article
The forearm skin of 10 Caucasians and 10 American Negroes was inoculated with Candida albicans and the severity of the ensuing dermatitis as well as the population of Candida and other aerobes in the inoculum site have been assessed. Negroid skin proved to be less susceptible to irritation, even though it harboured a higher population of yeasts and aerobes other than Candida.
Article
Reactivity of white and hispanic skin after exposure to sodium lauryl sulphate (SLS) has been investigated. The tests were performed on the back as follows: untreated skin, skin pre-treated with short-term occlusion and delipidized skin. Irritant reactions were induced by applying 0.5% and 2.0% SLS via Finn chamber patch tests and monitored by means of laser Doppler velocimetry (LDV), transepidermal water loss (TEWL) and stratum corneum water content (WC). Higher TEWL, LDV and WC were recorded for 2.0% SLS when compared to 0.5% SLS and baselines. Differences between white and hispanic skin reactivity were recorded. TEWL and WC responses showed a greater sensitivity in hispanics possibly reflecting a different modulation of the water barrier function after chemical exposure. On the other hand, the microcirculatory response, as long as detected with LDV, was similar in the 2 groups. Correlations between these data and findings observed in other races are discussed.
Article
In vivo transepidermal water loss studies are characterized by large inter-individual variability and biased by environmental effects and eccrine sweating. An in vitro technique for measuring transepidermal water loss (TEWL) was used to compare TEWL in two racial groups--blacks and whites. In both groups a significant correlation between skin temperature and increased TEWL was found (P less than 0.01). Furthermore, black skin had a significantly higher mean TEWL than white skin, corrected log TEWL 2.79 and 2.61 micrograms/cm2/h, respectively. The difference in TEWL between the groups could because measurements were made in the absence of eccrine sweating and other vital functions. The higher TEWL in black skin could be explained on the basis of a thermoregulatory mechanism. The anatomical and physiological differences in the stratum corneum between different races are discussed.
Article
The different reactivity of black and white skin after exposure to sodium lauryl sulphate (SLS) has been investigated. 9 white and 10 black male volunteers entered the study. The tests were performed on the back at 3 sites: untreated skin, skin pre-treated with occlusion and skin pre-delipidized. Irritant reactions were elicited applying 0.5% and 2.0% SLS via Finn chamber patch tests and monitored by means of laser Doppler velocimetry (LDV), transepidermal water loss (TEWL) and stratum corneum water content (WC). Higher TEWL, LDV, and WC values were recorded for 2.0% SLS when compared to 0.5% SLS and baselines. Pre-treatment with short-term occlusion generally increased values, while delipidization produced flattening of the data more detectable in whites than in blacks. Significant TEWL differences for the two concentrations were recorded in whites for the occluded site (P less than 0.02) while in blacks in the untreated (P less than 0.04) and delipidized (P less than 0.03) sites. LDV revealed significant changes in the untreated and pre-occluded white skin (P less than 0.05 and 0.01, respectively). In blacks, the values were significantly different only in the pre-occluded skin (P less than 0.01). Water content correlated with the visual score and was greatly increased in sites with strongly positive reactions (P less than 0.01). It appears that there are significant differences in the modulation of irritation, in the behavior of water barrier function and of the erythematous response between blacks and whites. Clinical correlations are discussed.
Article
UVB-induced erythema, delayed tanning (DT), and UVA-induced immediate tanning (IT) in Japanese were investigated on the skin of the backs of 65 healthy subjects. The subjects were classified according to Japanese skin type (JST) based on personal history of sun-reactivity. Skin color was determined by skin reflectance using a Value Reflex Meter. With monochromatic UVR at wavelengths of 290 and 305 nm, minimal erythema dose (MED) and minimal melanogenic dose (MMD) were recorded at 24 h and 7 d after irradiation. Fading response of DT after the sunlamp-irradiation was measured by skin reflectance. Minimal IT dose (MITD) was observed immediately after irradiation with monochromatic UVR at wavelengths of 320, 340, 360, and 400 nm. The MED was exactly correlated with JST. The MED and the MMD increased with increasing JST, and with decreasing skin reflectance. The MMD was greater than the corresponding MED for individuals of all JST classes. The MITD was correlated with neither JST nor skin color. The action spectrum for IT showed a maximum at the wavelength of 320 nm and decreased gradually towards 400 nm.
Article
Using fused-silica capillary gas chromatography, we investigated sebum samples from 55 healthy individuals to discover the effects of aging on the sebaceous gland activity and on the fatty acid composition of wax exters. The sebaceous gland activity, which was expressed by the ratio of wax esters/[cholesterol + cholesterol esters] (WE/[C + CE]), showed a distinct change from infancy through maturity to senescence; the curve of the ratio made a peak in our subjects's 20s. Using the fatty acid analyses, we found an interesting relationship between C16:1 straight and C16:1 iso-branched chains, each of which occupied a large proportion in the fatty acids of wax esters; the former increased in proportion from infancy toward the 20s, with a correlation with aging (r = 0.788, p less than 0.01), and decreased thereafter until our subject's 50s (r = -0.611, p less than 0.01). In contrast, the proportion of the latter followed an entirely reversed course with advancing age. The percentages of C16:1 straight chain components were correlated positively with the WE/[C + CE] ratio (r = 0.642, p less than 0.01), while there was found to be a negative correlation between the proportion of C16:1 iso-branched chain components and the WE/[C + CE] ratio (r = -0.556, p less than 0.01). The results suggest that more active sebaceous glands in lipid production excrete lipids with a higher proportion of C16:1 straight chain fatty acid and a lower proportion of C16:1 iso-branched chain fatty acid. As well as the sebaceous gland activity, the fatty acid composition in sebum wax esters is affected by advancing age in Japanese.
Article
The measurement of the rate of desquamation is an important parameter for epidermal cell kinetic considerations. In order to obtain such information, we have compared 2 existing techniques with a new one and with a modification of a little-used technique for determining the rate of cell loss from the stratum corneum. We have also studied regional and age variations in desquamation in normal skin. The results of the studies performed show there was a strong positive correlation between the “chamber” technique (which measures passive desquamation) and the “scrub” technique (measuring forced desquamation). There was similar strong negative correlation for the “scrub” technique and the dansyl chloride fluorescence method which measures stratum corneum renewal.
Article
The sunburn response is markedly reduced by dietary fish oil rich in omega-3 polyunsaturated fatty acids. Because prostaglandins mediate the vasodilatation, we examined the effect of fish oil on ultraviolet (UV) B-induced prostaglandin metabolism. In addition we assessed the potential photoprotective effect of fish oil in light-sensitive patients. Thirteen patients with polymorphic light eruption received dietary supplements of fish oil rich in omega-3 polyunsaturated fatty acids for 3 months. At baseline and 3 months, the minimal erythema dose of UVB irradiation was determined, and a graded UVA challenge given to a forearm to assess the threshold dose for papule provocation. Suction blisters were raised on the other forearm, on control skin, and on skin irradiated with four times the minimal erythema dose of UVB 24 h previously, and blister fluid prostaglandin E2 was measured by radioimmunoassay. Following 3 months of fish oil, the mean minimal erythema dose of UVB irradiation increased from 19.8 +/- 2.6 to 33.8 +/- 3.7 mJ/cm2 (mean +/- SEM), p < 0.01. The UVA provocation test was positive in 10 patients at baseline, and after 3 months nine of these showed reduced sensitivity to papule provocation, p < 0.001. Before fish oil, PGE2 increased from 8.6 (SEM 2.1) ng/ml in control skin to 27.2 (11) ng/ml after UVB, p < 0.01. Following 3 months of fish oil, PGE2 decreased to 4.1 (1) and 9.6 (2.4) ng/ml in control and irradiated skin, respectively, p < 0.05. Reduction of UV-induced inflammation by fish oil may be due, at least partially, to lowered prostaglandin E2 levels. The photoprotection against UVA-provocation of a papular response suggests a clinical application for fish oil in polymorphic light eruption.
Article
Previous studies that compared transepidermal water loss in subjects of different race and sex showed minimal differences in basal permeability barrier function. These studies often did not assess the ability of the stratum corneum to withstand or recover from insults to the epidermal permeability barrier. We compared epidermal permeability barrier function in the following human subjects (age range, 22 to 38 years): white (n = 8) vs Asian (n = 6); male (n = 7) vs female (n = 7); and skin type II/III (n = 14) vs skin type V/VI (n = 7) (scale, I to VI). Basal transepidermal water loss was measured by evaporimetry (three sites) on the volar aspect of the forearm. Barrier integrity then was assessed by determining the number of tape strippings required to reach a transepidermal water loss greater than or equal to 20 g/m2 per hour. The rates of barrier recovery then were compared at 6, 24, and 48 hours and 1 week after abrogation. Neither the number of tape strippings required to perturb the barrier nor the rates of barrier recovery were significantly different in white vs Asian subjects or in female vs male subjects. However, patients with skin types II/III required only 29.6 +/- 2.4 tape strippings to perturb the barrier, while the skin type V/VI group required 66.7 +/- 6.9 tape strippings. Furthermore, while barrier function in skin type II/III recovered by approximately 20% by 6 hours and 55% by 48 hours, barrier function in skin type V/VI, independent of race, recovered more quickly, 43% and 72% at 6 and 48 hours, respectively. Finally, neither the differences in barrier integrity nor in rates of recovery could be attributed to variations in cohesiveness, since stripping appears to remove the same weight of stratum corneum in both groups. Darkly pigmented skin displays both a more resistant barrier and one that recovers more quickly after perturbation by tape stripping than does the skin of individuals with lighter pigmentation. These findings have potential implications for transdermal delivery of topical or systemic therapeutic agents, the ability of individuals with different skin types to withstand environmental or occupational insults, and the influence of acquired hyperpigmentation or pigment loss to influence permeability.
Article
The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
Article
Clinical assessments of photodamage are based upon a subjective evaluation of characteristic features such as wrinkling and pigmentary change, and are influenced by inter-observer differences in grading criteria. In an effort to standardize the grading of photodamage severity, we have developed a six-point photographic scale in which each of the six grades of overall photodamage severity is depicted by three photographs. The use of three photographs to portray each grade illustrates the diversity and range of manifestations within each grade. This photographic scale was tested by two groups of dermatologists, who used it on two occasions to grade the overall photodamage severity of a single group of female Caucasian subjects. Results indicate high inter-observer agreement, with chance-corrected agreement ranging from 0.44 to 0.63 and from 0.54 to 0.76 on the first and second occasions, respectively. Intra-observer repeatability was high, with chance-corrected agreement ranging from 0.56 to 0.78. Inter- and intra-observer differences were within one category in nearly all cases. Similar grades were assigned by dermatologists with and without experience in treating photodamaged patients. We conclude that application of this scale results in consistent and reproducible clinical evaluations of overall photodamage severity in Caucasian subjects. The scale may be useful in categorizing subjects for epidemiological studies, or in selecting patients for clinical trials.
Article
An individual's sensitivity to sunlight is traditionally assessed by the Boston or Fitzpatrick classification of skin type. The ability to tan depends, to some degree, on the melanin content of the epidermis. In the study reported here, surface corneocytes in exposed skin and unexposed skin have been assessed using a surface stripping slide mounting technique and an Optomax V image analyser, with which the percentage of corneocyte area occupied by melanin granules has been taken as the melanin content index (MCI). There was a significantly different MCI between different skin types for both exposed (P < 0.0001) and unexposed (P < 0.0001) areas using the Kruskal-Wallis one-way ANOVA test. There was also a positive significant correlation between MCI and skin types II-VI in both exposed (r = 0.95, P < 0.001) and unexposed areas (r = 0.89, P < 0.005). Image analysis also demonstrated that the number of melanin granules in surface corneocytes was significantly higher in the exposed area compared with the unexposed area, for skin types II, III, IV, V and VI. Melanin cap-like structures were also observed in exposed corneocytes and heavily pigmented skin contained larger melanin particles than fairer skin. The results indicate that an individual's skin phototype and melanin content, assessed by image analysis, have a significant correlation.