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Background: Seborrheic dermatitis is a chronic and recurring skin disorder with clinical manifestations as erythematous macules or plaques with a scale associated with pruritus. The most common predilection is the face area. Treatments for seborrheic dermatitis should address the normalization process of skin function and structure, not only relieving the symptoms and clinical symptoms of the disease. Thus, leading to long-term remission. Objective: The narrative review was conducted by reviewing the articles that discussed about the treatment effectiveness on facial seborrheic dermatitis. Methods: Articles search was carried out through databases such as Pubmed and Google Scholar with determined keywords and selected based on inclusion and exclusion criteria. Results: In total, six articles were reviewed with 184 cases of facial dermatitis seborrheic. All studies showed significant improvement. This review included additional literatures to support the results of the main literatures. Conclusion: The treatments commonly used for seborrheic dermatitis these days are pharmacological treatments in the form of topical and systemic drugs as well as non-pharmacological treatments. Topical drugs were able to repair the clinical manifestation on mild to moderate seborrheic dermatitis whereas systemic drugs were indicated for cases with wide lesions and more severe condition. Non-pharmacological treatment can be used as an adjuvant to accelerate the clinical condition.

Coronavirus is a disease that affects mainly the upper respiratory tract, but in somecases, it can also affect the skin. This study aims to describe the effect of coronavirus on the skin function. Skin gets affected easily because coronavirus first comes into contact with the skin and mucous membrane. Numerous studies are investigating the symptoms of coronavirus appearing on the skin in different forms like rashes, blisters, irritation, dermatitis, etc. The excessive use of sanitizers and soaps can also cause skin problems. Personal protective equipment can also cause irritation to the skin and mucous membrane. It is concluded from the study that skin must be protected from the exposure of the external environment where the virus may be present. Moreover, sanitizers and soaps must be used in a limited quantity and proper medication should be taken by the patients having a skin disease because they may get affected with the coronavirus.

Michael Paul Wakeman Department of Cancer Sciences, School of Medicine, University of Birmingham, Edgbaston, Birmingham,UK Background: This study examines the efficacy of a new plant-based emollient and assesses product acceptability.Methods: Primary efficacy endpoints were improvement in transepidermal water loss, hydration, skin elasticity and firmness, erythema, and skin roughness and smoothness as measured using the versions of Tewameter, Corneometer, Cutometer, Mexameter, and Visioscan VC98, respectively. The cream was applied twice daily by 32 participants to an area of one forearm unaffected by eczema, while the same area of the other forearm was used as a control. Measurements were taken at day 0 and day 14. Secondary endpoints assessed the acceptability of the product.Results: At the end of 2 weeks, transepidermal water loss, hydration, skin elasticity and firmness, erythema, and skin roughness and smoothness improved. All changes were statistically significant (p

Background: Plant-derived ceramides are functional natural products with vari-ous physiological effects that improve water retention and skin permeability functions. Objective: Herein, we isolated peach (Prunus persica)-derived glucosylceramide with high purity and evaluated its effects on moisture and permeability of skin. Methods: Three separate experiments were performed: evaluations of the effect of peach-derived glucosylceramide application on the ceramide content in a three-dimensional hu-man cultured skin model, water retention effect of the oral administration of the peach-derived glucosylceramide on human skin functionality, and safety of the long-term admin-istration of the peach-derived glucosylceramide in human subjects. Results: Treatments of three-dimensional cultures of human skin with peach-derived gluco-sylceramide led to dose-dependent increases in human ceramide contents. Additionally, af-ter oral administration of ceramide to humans, dose-dependent improvements in water re-tention functions of skin, suppression of trans-epidermal water loss and improvements in skin texture were observed. Furthermore, no significant changes in subjective/objective symptoms, physical characteristics, or laboratory test values were observed in human sub-jects following long term oral administration of ceramide at doses that were 4.5-9-times greater than recommended. Taken together, the present data indicate the positive effects of peach ceramide on skin function and no adverse effects.

Urea is an emollient widely used in clinical dermatology to moisturise and protect the skin. Non-invasive techniques can be useful in evaluating and quantifying the moisturising and hydrating properties of topically applied urea. Amongst these, transepidermal water loss, skin conductance and capacitance are the most widely used. Dynamic tests and mapping of skin moisturisation are additional features that can be used to evaluate the dynamics of water into the stratum corneum. Ultrasound and mechanical properties can be used to investigate the effects on skin smoothness and tone. In conclusion, urea is a fundamental ingredient of cosmetic and dermatological formulations and can have several positive effects on skin function. These can be easily investigated and monitored using non-invasive techniques measuring the stratum corneum function.

The skin is the largest organ in mammals and serves as a protective barrier at the interface between the human body and the surrounding environment. It guards the underlying organs and protects the body against pathogens and microorganisms. Accordingly, it is directly exposed to potentially harmful microbial, thermal, mechanical and chemical influences. Simulating skin function aims for different biomaterials evaluation and for explorations of fundamental biological processes. In this mini review, we summarize in vitro methods that simulate skin hydration, aging and photoaging process, wound healing and menopause, high lightening novel efforts in the design of in vitro studies for the development of skin care products.

Chytridiomycosis, a lethal skin disease caused by the fungal pathogen Batrachochytrium dendrobatidis ( Bd), disrupts skin function of amphibians, interfering with ionic and osmotic regulation. To regulate fungal loads, amphibians increase their rate of skin sloughing. However, sloughing also causes a temporary loss of ionic and osmotic homeostasis due to disruption of the skin, a key osmoregulatory organ. The combined effects of increased sloughing frequency and chytridiomycosis contribute to the high rates of mortality from Bd infections. However, the mechanisms responsible for the loss of cutaneous osmotic regulation remain unknown. We measured the changes in whole animal water uptake rates, in vitro transcutaneous water fluxes across the ventral skin, and the mRNA expression of epithelial water transport proteins (aquaporins, AQPs) and junctional proteins in Bd-infected and uninfected Litoria caerulea skin. We hypothesize that infected frogs would show reduction/inhibition in cutaneous water transporters responsible for regulating water balance, and sloughing would exacerbate cutaneous water fluxes. We found that infected, nonsloughing frogs had an impaired rate of water uptake and showed increased rates of in vitro water efflux across the ventral skin. In uninfected frogs, the expression of AQPs and junction genes increased significantly with sloughing, which may assist in regulating cutaneous water movements and barrier function in the newly exposed skin. In contrast, infected frogs did not show this postsloughing increase in AQP gene expression. The combination of increased sloughing frequency, impaired water uptake rates, and increased rates of water loss likely contributes to the loss of osmotic homeostasis in frogs infected with Bd.

Introduction : Complications of diabetes can damage internal organs and the skin. Diabetic skin, irritated and dry, is susceptible to skin infections. However little is known about influence of emollients on biophysical changes in skin during diabetes. Aim : To evaluate clinical skin changes after application of emollients with benfothiamine and Biolin prebiotic and to assess changes in biophysical parameters of the skin before and 4 weeks after daily application of an emollient. Material and methods : We recruited 50 patients with diabetes mellitus type 1 (DM1) or type 2 (DM2). All participants applied emollients on their left forearms and left shins for 4 weeks. The biophysical properties: pH, transepidermal water loss (TEWL), hydration of the stratum corneum and sebum content were measured and compared to those before enrollment to the study, after 1 h, 1 week and 4 weeks after application of an emollient. Results : After 4 weeks of treatment, there was an increase in skin hydration (40.61 ±19.03 vs. 48.83 ±15.51), pH (5.11 ±0.56 to 5.27 ±0.48) and sebum content (22.16 ±8.67 to 63.99 ±25.41) and a decrease in TEWL (12.54 ±5.6 vs. 9.85 ±5.69 g/m2/h) on forearms (p < 0.05 for all comparisons). On lower legs, significant changes in skin hydration (37.21 ±14.01 vs. 43.95 ±12.67), pH (5.04 ±0.57 to 5.31 ±0.49), sebum content (25.82 ±10.46 to 72.63 ±31.23) and TEWL (8.87 ±4.05 vs. 7.39 ±3.22 g/m2/h) were observed (p < 0.05 for all comparisons). Conclusions : Our study provides an insight into changes in diabetic skin after application of an emollient. To our knowledge, this is the first report on the emollient containing benfothiamine and Biolin prebiotic and its influence on biophysical parameters of epidermis.

The epidermis at the forefront of the skin, wraps around the entire body and acts as a barrier to prevent the loss of internal moisture and the invasion of foreign substance. Its involvement in the transduction of external stimuli has been reported, and there has been growing interest in its intelligent aspects in recent years. A potential difference, called the transepidermal potential (TEP), is generated across the epidermis, and its magnitude is about tens of mVs where its surface is negative [1]. Active ion transportation by the epidermal keratinocytes is seemed to generate TEP, and its value changes according to the state of epidermal wounds and barrier. Unfortunately, the lack of an appropriate method for TEP measurement has hindered the progress of the research for decades. As TEP is generated across the epidermis, measuring electrodes have to be connected to the outside of the epidermis (surface of the skin) and the inside of the epidermis (tissue under the epidermis). Typically, a wound is created as an electrical path to the subepidermal tissue, despite its invasiveness. As an alternative, sublingual mucosa was utilized as a potential reference, suffering from the interference of other tissues. In this study, we developed a minimally invasive measurement method and applied it to the evaluation and control of skin function. To measure relatively small resting potential, a pair of reversible Ag/AgCl electrodes were connected to the inside and outside of the epidermis via a salt bridge. A commercially available painless medical micro-needle (Nanopass 34G, Terumo) was employed to support the salt bridge for subepidermal connection. The external diameter of the needle was 0.18 mm (34 G), which minimized the damage accompanied by the insertion. The salt bridge was made biocompatible from Ringer's solution and agarose, and held in the hydrophilized needle, which could quickly soak up tissue fluid and stabilize the ionic conduction. Then the needle salt bridge for subepidermal tissue and a tubular salt bridge for the surface of the epidermis were bundled into a measuring probe (Figure 1A) [2]. For ex vivo measurement, porcine skin samples were used to observe the disruption and recovery of epidermal barrier induced by visible light stimulation. In vivo measurements were performed on human participants. All procedures performed in studies involving human participants were in accordance with the standards of the Ethics Committee of Graduate School of Engineering, Tohoku University (16A-5) and with the 1964 Helsinki declaration and its later amendments. In vivo measurements in human participants successfully observed a decrease in TEP according to the experimental barrier disruption, accompanied by an increase in the amount of water evaporation across the skin (Figure 1B) [3]. The penetration depth of the needle was about 1 mm, allowing access into the epidermis with minimal invasion. Compared to the water evaporation, which requires the controlled atmosphere for measurement, TEP was reflected by the electrical properties of the inside of the epidermis, and expected to be suitable for on-demand measurement. TEP of porcine skin sample also showed decrease along with the barrier disruption, and application of electrical potential that have been reported to therapeutic effect on skin barrier [4] caused greater recovery (Figure 1C). These results indicate that the developed device would be a practical tool for less-invasive TEP potential, and suggest further application of it in the electrical diagnosis and cure. References [1] A. T. Barker, L. F. Jaffe, and J. W. Vanable Jr., “The glabrous epidermis of cavies contains a powerful battery.”, Am. J. Physiol., 242, R358–R366, (1982) [2] Y. Abe et al., “Minimally-invasive transepidermal potentiometry with microneedle salt bridge”, Biomed. Microdevices, 18, 55, (2016) [3] Y. Abe et al., “Red light-promoted skin barrier recovery: Spatiotemporal evaluation by transepidermal potential”, PLoS One, 14, e0219198, (2019) [4] M. Denda, and N. Kumazawa, “Negative electric potential induces alteration of ion gradient and lamellar body secretion in the epidermis, and accelerates skin barrier recovery after barrier disruption”, J. Invest. Dermatol., 118, 65–72, (2002) Figure 1

The forkhead box N1 (Foxn1) transcription factor regulates biological processes of the thymus and skin. Loss-of-function mutations in Foxn1 cause the nude phenotype in humans, mice, and rats, which is characterized by hairless skin and a lack of thymus. This review focuses on the role of Foxn1 in skin biology, including epidermal, dermal, and dermal white adipose tissue (dWAT) skin components. In particular, the role of Foxn1 in the scar-forming skin wound healing process is discussed, underscoring that Foxn1 inactivity in nude mice is permissive for scar-less cutaneous wound resolution.

Ageing of populations has emerged as one of the most pressing societal, economic and healthcare challenges currently facing most nations across the globe. The ageing process itself results in degradation of physiological functions and biophysical properties of organs and tissues, and more particularly those of the skin. Moreover, in both developed and emerging economies, population ageing parallels concerning increases in lifestyle-associated conditions such as Type 2 diabetes, obesity and skin cancers. When considered together, these demographic trends call for even greater urgency to find clinical and engineering solutions for the numerous age-related deficits in skin function.\ud \ud From a tribological perspective, detrimental alterations of skin biophysical properties with age have fundamental consequences on how one interacts with the body's inner and outer environments. This stems from the fact that, besides being the largest organ of the human body, and also nearly covering its entirety, the skin is a multifunctional interface which mediates these interactions.\ud \ud The aim of this paper is to present a focused review to discuss some of the consequences of skin ageing from the viewpoint of biotribology, and their implications on health, well-being and human activities. Current and future research questions/challenges associated with biotribology of the ageing skin are outlined. They provide the background and motivation for identifying future lines of research that could be taken up by the biotribology and biophysics communities.

We compare here the principal characteristics of over-the-counter moisturizers with physiologic lipid-based barrier repair therapy. Moisturizers are standard ancillary therapy for anti-inflammatory skin disorders, like atopic dermatitis (AD), and can attenuate the emergence of AD, the initial step in the “atopic march.” But not all moisturizers are beneficial; some can make skin function worse, and can even induce inflammation, possibly accounting for the frequent occurrence of “sensitive skin” in women. In contrast, physiologic lipid-based barrier repair therapy, if comprised of the 3 key stratum corneum lipids, in sufficient quantities and at an appropriate molar ratio, can correct the barrier abnormality and reduce inflammation in AD, and perhaps in other inflammatory dermatoses.

Individual responses of human skin to the environmental stress are determined by differences in the anatomy and physiology that are closely linked to the genetic characteristics such as pigmentation. Ethnic skin phenotypes can be distinguished based on defined genotypic traits, structural organization and compartmentalized sensitivity to distinct extrinsic aging factors. These differences are not only responsible for the variation in skin performance after exposure to damaging conditions, but can also affect the mechanisms of drug absorption, sensitization and other longer term effects. The unique characteristics of the individual skin function and, particularly, of the ethnic skin type are currently considered to shape the future of clinical and pharmacologic interventions as a basis for personalized skincare. Individual approaches to skincare render a novel and actively growing area with a range of biomedical and commercial applications within cosmetics industry. In this review, we summarize the aspects of the molecular and clinical manifestations of the environmental stress on human skin and proposed protective mechanisms that are linked to ethnic differences and pathophysiology of extrinsic skin aging. We subsequently discuss the possible applications and translation of this knowledge into personalized skincare.

Skin is the first line of defense for protecting our bodies against external perturbations, including ultraviolet (UV) irradiation, mechanical/chemical stress, and bacterial infection. Nutrition is one of many factors required for the maintenance of overall skin health. An impaired nutritional status alters the structural integrity and biological function of skin, resulting in an abnormal skin barrier. In particular, the importance of micronutrients (such as certain vitamins and minerals) for skin health has been highlighted in cell culture, animal, and clinical studies. These micronutrients are employed not only as active compounds in therapeutic agents for treating certain skin diseases, but also as ingredients in cosmetic products. Here, the author describes the barrier function of the skin and the general nutritional requirements for skin health. The goal of this review is to discuss the potential roles and current knowledge of selected micronutrients in skin health and function.

Evidence suggests a protective role for several nutrients and foods in the maintenance of skin function. Nevertheless, all the requests for authorization to use health claims under Article 13(5) in the framework of maintenance of skin function presented to the European Food Safety Authority (EFSA) have received a negative opinion. Reasons for such failures are mainly due to an insufficient substantiation of the claimed effects, including the choice of inappropriate outcome variables (OVs) and methods of measurement (MMs). The present paper reports the results of an investigation aimed at collecting, collating and critically analyzing the information with relation to claimed effects (CEs), OVs and MMs related to skin health compliance with Regulation 1924/2006. CEs, OVs and MMs were collected from both the EFSA Guidance document and from the authorization requests of health claims under Article 13(5). The critical analysis of OVs and MMs was based on a literature review, and was aimed at defining their appropriateness (alone or in combination with others) in the context of a specific CE. The results highlight the importance of an adequate choice of OVs and MMs for an effective substantiation of the claims.

Background Obesity is considered problematic not only as a major cause of diabetes, hypertension, and dyslipidemia, but also as a risk of intractable dermatosis; however influence of obesity on skin function has not been clarified. To clarify the mechanism of obesity-associated skin disorders, we aimed to characterize the skin function of subjects with obesity, and identify possible influencing factors. Methods Complex analyses including instrumental measurement, biochemical and lipidomics were performed for facial skin and physical evaluation in 93 Caucasian women with obesity (OB) and non-obesity (NOB). Results In OB, imbalance in metabolism of carbohydrate and lipid, autonomic nerve activity, and secreted factors were confirmed. In the skin properties in OB, surface roughness was higher by 70%, the water content was lower by 12%, and changes in the lipid profile of stratum corneum ceramide were observed; in particular, a 7% reduction of [NP]-type ceramide, compared with NOB. Moreover, significant redness accompanied by a 34% increase in skin blood flow was observed in OB. Correlation analysis elucidated that the water content was strongly correlated with local skin indices, such as the ceramide composition, redness, blood flow, and TNFα in the stratum corneum, whereas roughness was correlated with the systemic indices, such as serum insulin, leptin, and IL-6. Conclusions Characteristics of obesity-associated skin were (A) reduction of the barrier and moisturizing function accompanied by intercellular lipid imbalance, (B) increased redness accompanied by hemodynamic changes, and (C) surface roughness. It was suggested that each symptom is due to different causes in local and/or systemic physiological impairment related to the autonomic nerve-vascular system, inflammation and insulin resistance.

Background Skin is a multilayer interface between the body and the environment, responsible for many important functions, such as temperature regulation, water transport, sensation, and protection from external triggers. Objectives This paper provides an overview of principal factors that influence human skin and describes the diversity of skin characteristics, its causes and possible consequences. It also discusses limitations in the barrier function of the skin, describing mechanisms of absorption. Methods There are a number of in vivo investigations focusing on the diversity of human skin characteristics with reference to barrier properties and body-dependent factors. Results Skin properties vary among individuals of different age, gender, ethnicity, and skin types. In addition, skin characteristics differ depending on the body site and can be influenced by the body-mass index and lifestyle. Although one of the main functions of the skin is to act as a barrier, absorption of some substances remains possible. Conclusions Various factors can alter human skin properties, which can be reflected in skin function and the quality of everyday life. Skin properties and function are strongly interlinked.

Skin function deteriorates with aging, and the dermal water content decreases. In this study, we have analyzed the mechanism of aging-related skin dryness focusing on aquaporins (AQPs), which are the water channels. Mice aged 3 and 20 months were designated as young and aged mice, respectively, to be used in the experiments. No differences were observed in transepidermal water loss between the young mice and aged mice. However, the dermal water content in aged mice was significantly lower than that in young mice, thus showing skin dryness. The expression of AQP1, AQP3, AQP4, AQP7, and AQP9 was observed in the skin. All the mRNA expression levels of these AQPs were significantly lower in aged mice. For AQP3, which was expressed dominantly in the skin, the protein level was lower in aged mice than in young mice. The results of the study showed that the expression level of AQPs in the skin decreased with aging, suggesting the possibility that this was one of the causes of skin dryness. New targets for the prevention and treatment of aging-related skin dryness are expected to be proposed when the substance that increases the expression of AQP3 is found.

Earlier studies showed that dermal cells lose trichogenic capacity with passage, but studies on the effect of keratinocyte passage on human hair follicle neogenesis and graft quality have been hampered by the lack of a suitable model system. We recently documented human hair follicle neogenesis in grafted dermal-epidermal composites, and in the present study, we determined the effects of keratinocyte passage on hair follicle neogenesis. Dermal equivalents were made with cultured human dermal papilla cells and were overlaid with either primary or passaged human keratinocytes to form dermal-epidermal composites; these were then grafted onto immunodeficient mice. Superior hair follicle neogenesis was observed using early keratinocyte cultures. Characteristics such as formation of hair shafts and sebaceous glands, presence of hair follicles with features of anagen or telogen follicles, and reproducible hair and skin function parameters make this model a tool to study human hair follicle neogenesis and development.

Background Skin function is dependent on its biomechanical characteristics, resistance, malleability, and elasticity. Therapeutic ultrasound may increase cutaneous malleability thus and optimize the rehabilitation process on specific diseases. The aim of this study is to evaluate possible alterations of biomechanical characteristics of the normal skin after therapeutic ultrasound application. Methods Thirty-one volunteers took part of the study, and the average age was 31.61 ± 8.37 years old. Biomechanical characteristics evaluation of the skin was performed with the Cutometer MPA 580 (Courage + Khazaka Electronic—Köln, Germany) of 2-mm probe hole and 500-mbar vacuum. Skin characteristics were analyzed before and after therapeutic ultrasound application, and the variables R0 (distensibility), R2 (gross elasticity), and R6 (viscoelasticity) were used for the study. Areas of therapeutic ultrasound application (continuous, 3 MHz, 1 W/cm2 SATA) were defined at the upper limbs and standardized using a neoprene template. Sociodemographic data of volunteers were analyzed using SPSS 15.0. To analyze the distribution of the data, the Shapiro-Wilk test was used, which showed the normal distribution for R0 values, R2 and R6. For this procedure, the PROC TTEST from SAS® 9.0 software and Minitab 16 software, with significance, was set at the 0.05 level. Results In relation to R0, a significant increase (p = 0.001) was observed for the distensibility, when compared to values of pre- (0.3273 mm) and immediately post- (0.3795 mm) resource application which feature a greater distensibility. Related to R2 values, a significant increase (p = .001) of the gross elasticity at pre- (0.8419) and post- (0.8884) therapeutic ultrasound application was found. Conclusions Therapeutic ultrasound promotes significant alterations of the biomechanical characteristics of the skin. Trial registration ClinicalTrials.gov, 1111-1146-7342

Ultraviolet(UV)rays are suggested to be one of the factors responsible for skin photoaging induced by active oxygen species. In recent years, it has been reported that the intake of some compounds such as carotenoids prevented UV-induced photoaging. This study aims to investigate the effect of herb tea intake on the skin function of hairless mice irradiated with UV rays. The mice were given the following types of herb tea: Lavandula angustifolia, Malva sylvestris, Calluna vulgaris, Rosa laevigata, and Emblica officinalis. The skin condition of the Malva sylvestris-given mice was the best among all the experimental mice groups. Malva sylvestris had the lowest antioxidant activity and total polyphenolic content. While we could not identify the underlying mechanism, we infer that the long-term intake of herb tea such as Malva sylvestris increases the barrier function of the corneum and the water content of the epidermis.

Degenerative skin diseases affect one third of individuals over the age of sixty. Current therapies use various physical and chemical methods to rejuvenate skin; but since the therapies affect many tissue components including cells and extracellular matrix, they may also induce significant side effects, such as scarring. Here we report on a new, non-invasive, non-thermal technique to rejuvenate skin with pulsed electric fields. The fields destroy cells while simultaneously completely preserving the extracellular matrix architecture and releasing multiple growth factors locally that induce new cells and tissue growth. We have identified the specific pulsed electric field parameters in rats that lead to prominent proliferation of the epidermis, formation of microvasculature and secretion of new collagen at treated areas without scarring. Our results suggest that pulsed electric fields can improve skin function and thus can potentially serve as a novel non-invasive skin therapy for multiple degenerative skin diseases.

Background Obesity is considered problematic not only as a major cause of diabetes, hypertension, and dyslipidemia, but also as a risk of intractable dermatosis; however influence of obesity on skin function has not been clarified. To clarify the mechanism of obesity-associated skin disorders, we aimed to characterize the skin function of subjects with obesity, and identify possible influencing factors. Methods Complex analyses including instrumental measurement, biochemical and lipidomics were performed for facial skin and physical evaluation in 93 Caucasian women with obesity (OB) and non-obesity (NOB). Results In OB, imbalance in metabolism of carbohydrate and lipid, autonomic nerve activity, and secreted factors were confirmed. In the skin properties in OB, surface roughness was higher by 70%, the water content was lower by 12%, and changes in the lipid profile of stratum corneum ceramide were observed; in particular, a 7% reduction of [NP]-type ceramide, compared with NOB. Moreover, significant redness accompanied by a 34% increase in skin blood flow was observed in OB. Correlation analysis elucidated that the water content was strongly correlated with local skin indices, such as the ceramide composition, redness, blood flow, and TNFα in the stratum corneum, whereas roughness was correlated with the systemic indices, such as serum insulin, leptin, and IL-6. Conclusions Characteristics of obesity-associated skin were (A) reduction of the barrier and moisturizing function accompanied by intercellular lipid imbalance, (B) increased redness accompanied by hemodynamic changes, and (C) surface roughness. It was suggested that each symptom is due to different causes in local and/or systemic physiological impairment related to the autonomic nerve-vascular system, inflammation and insulin resistance. Electronic supplementary material The online version of this article (10.1186/s12944-017-0608-1) contains supplementary material, which is available to authorized users.

Circadian rhythms are present in most functions of living beings. We have demonstrated the presence of circadian rhythms in skin variables (transepidermal water loss, TEWL; stratum corneum hydration, SCH; and skin temperature) in hairless rats under different environmental conditions of light and temperature. Circadian rhythms in TEWL and SCH showed mean amplitudes of about 20% and 14% around the mean, respectively, and appeared under light-dark cycles as well as under constant darkness. Environmental temperature was able to override TEWL, but not SCH rhythm, evidencing the dependency of TEWL on the temperature. Mean daily values of TEWL and SCH, and also the amplitude of TEWL rhythm, increased with the age of the animal. Under constant light, situation that induces arrhythmicity in rats, SCH and TEWL were inversely correlated. The results suggest the importance to take into account the functional skin rhythms in research in dermatological sciences.

The skin is the largest organ of the human body and plays a major role in maintaining homeostasis and protection. As the main component of skin, collagen has a key role in providing integrity and elasticity to this organ. Several factors, including autoimmune disease, aging, and stress, can change the quantity and integrity of skin collagen. These factors impair collagen quality and consequently affect skin function. Stress seems to affect the integrity of skin collagen through glucocorticoid-mediated processes that alter its synthesis and degradation. Glucocorticoids also affect skin quality through modulation of the immune system. This review will briefly present comprehensive data from both animal and human studies delineating processes that modulate alterations in collagen in general, and will treat in more detail the consequences of stress on skin collagen.

The pathobiology of vitiligo has been hotly disputed for as long as one remembers, and has been a magnet for endless speculation. Evidently, the different schools of thought--ranging, e.g. from the concept that vitiligo essentially is a free-radical disorder to that of vitiligo being a primary autoimmune disease--imply very different consequences for the best therapeutic strategies that one should adopt. As a more effective therapy for this common, often disfiguring pigmentary disorder is direly needed, we must strive harder to settle the pathogenesis debate definitively--on the basis of sound experimental evidence, rather than by a war of dogmatic theories. Recognizing, however, that it is theories which tend to guide our experimental designs and choice of study parameters, the various pathogenesis theories on the market deserve to be critically, yet unemotionally re-evaluated. This Controversies feature invites you to do so, and to ask yourself: is there something important or worthwhile exploring in other pathogenesis scenarios than those already favoured by you that may help you improve your own study design, next time you have a fresh look at vitiligo? Vitiligo provides a superb model for the study of many fundamental problems in skin biology and pathology. Therefore, even if it later turns out that, as far as your own vitiligo pathogenesis concept is concerned, you have barked-up the wrong tree most of the time, chances are that you shall anyway have generated priceless new insights into skin function along the way.

The dermal route of exposure is important in worker exposure to biocidal products. Many biocidal active substances which are used on a daily basis may decrease the barrier function of the skin to a larger extent than current risk assessment practice addresses, due to possible skin effects of repeated exposure. The influence of repeated and single exposure to representative biocidal active substances on the skin barrier was investigated in vitro. The biocidal active substances selected were alkyldimethylbenzylammonium chloride (ADBAC), boric acid, deltamethrin, dimethyldidecylammonium chloride (DDAC), formaldehyde, permethrin, piperonyl butoxide, sodium bromide, and tebuconazole. Of these nine compounds, only the quaternary ammonium chlorides ADBAC and DDAC had a clear and consistent influence on skin permeability of the marker compounds tritiated water and [14C]propoxur. For these compounds, repeated exposure increased skin permeability more than single exposure. At high concentrations the difference between single and repeated exposure was quantitatively significant: repeated exposure to 300 mg/L ADBAC increased skin permeability two to threefold in comparison to single exposure. Therefore, single and repeated exposure to specific biocidal products may significantly increase skin permeability, especially when used undiluted. © 2005 Elsevier Inc. All rights reserved.