Cutaneous sodium lauryl sulphate irritation potential: age and regional variability

The impact of irritant challenge on the skin barrier and myeloid-resident immune cells in women who are postmenopausal is modulated by hormone replacement therapy

BACKGROUND

Sex hormone changes during menopausal transition contribute to declining skin health. However, how menopause and its treatment by hormone replacement therapy (HRT) impact the skin barrier and immune system is unclear.

OBJECTIVES

To examine how menopause and HRT affect the skin barrier and immune cell composition in postmenopausal women following irritant challenge.

METHODS

Two cohorts of postmenopausal women were recruited to the study. The first cohort consisted of 10 untreated women [HRT-; mean (SEM) age 56.5 (1.6) years (range 48-63)] and the second was composed of 8 women receiving HRT [HRT+; mean (SEM) age 54.0 (2.1) years (range 48-63)]. Skin irritation was induced by applying topical sodium lauryl sulfate (SLS) 1.25% to occluded buttock skin for 48 h. Clinical assessment was conducted after 24 h, followed by biopsy of both SLS-challenged and unchallenged skin for analysis of skin barrier proteins and immune cell distribution using immunofluorescence.

RESULTS

Clinically, there were no significant differences in skin irritant responses between those taking or not taking HRT (including increased skin redness and blood flow). In response to SLS challenge a significant increase in transepidermal water loss (P < 0.05), filaggrin deposition and cytokeratin 10 (K10)+ cell layers (P < 0.01) was observed in individuals receiving HRT compared with the HRT- group. Following SLS challenge in individuals taking HRT, a significant (P < 0.01) reduction in CD207+ cells in the epidermis was observed, accompanied by an increase of CD207+ cells in the dermis, indicative of migrating Langerhans cells (LCs). Significantly fewer migrating LCs were found in those who were not receiving HRT (P < 0.01). Furthermore, the numbers of dermal dendritic cells (DCs), macrophages, and CD11c+CD206- and CD68+CD206- subsets were found to be significantly (P < 0.05) higher in those taking HRT following SLS challenge.

CONCLUSIONS

Individuals receiving HRT displayed enhanced skin barrier response to SLS challenge with thicker filaggrin and increased K10+ epidermal cell layers. Following challenge, HRT users exhibited elevated LC, inflammatory DC and macrophage counts in the dermis. These may render skin both more prone to inflammation and more capable of resolving it, while also promoting skin repair.

Itch and Pain Behaviors in Irritant Contact Dermatitis Produced by Sodium Lauryl Sulfate in Mice

Irritant contact dermatitis (ICD) is a nonspecific skin inflammation caused by irritants, leading to itch and pain. We tested whether differential responses to histamine-dependent and -independent pruritogens can be evoked in ICD induced by sodium lauryl sulfate (SLS). An ICD mouse model was established with 5% SLS in acetone versus a vehicle topically applied for 24 h to the cheek. Site-directed itch- and pain-like behaviors, occurring spontaneously and in response to mechanical, thermal, and chemical stimuli (histamine, ß-alanine, BAM8-22, and bradykinin) applied to the cheek, were recorded before (day 0) and after irritant removal (days 1, 2, 3, and 4). Skin inflammation was assessed through visual scoring, ultrasound, and measurements of skin thickness. SLS-treated mice exhibited hyperalgesia-like behavior in response to mechanical and heat stimuli on day 1 compared to the controls. SLS mice exhibited more spontaneous wipes (pain) but not scratching bouts (itch) on day 1. Pruritogen injections caused more scratching but not wiping in SLS-treated mice compared to the controls. Only bradykinin increased wiping behavior compared to saline. SLS-treated mice developed noticeable erythema, scaling, and increased skin thickness on days 1 and 2. SLS induced cutaneous inflammation and behavioral signs of spontaneous pain and itching, hyperalgesia to mechanical and heat stimuli and a chemical algogen, and enhanced itch response to pruritogens. These sensory reactions preceded the inflammation peak and lasted up to two days.

Skin homeostasis: Mechanism and influencing factors

BACKGROUND

The skin is the largest organ in the human body, not only resisting the invasion of harmful substances, but also preventing the loss of moisture and nutrients. Maintaining skin homeostasis is a prerequisite for the proper functioning of the body. Any damage to the skin can lead to a decrease in local homeostasis, such as ultraviolet radiation, seasonal changes, and air pollution, which can damage the skin tissue and affect the function of the skin barrier.

OBJECTIVE

This article reviews the maintenance mechanism and influencing factors of skin homeostasis and the symptoms of homeostasis imbalance.

METHODS

We searched for articles published between 1990 and 2022 in English and Chinese using PubMed, Web of Science, CNKI, and other databases in the subject area of dermatology, using the following search terms in various combinations: "skin homeostasis," "skin barrier," and "unstable skin." Based on our results, we further refined our search criteria to include a series of common skin problems caused by the destruction of skin homeostasis and its treatments. Limitations include the lack of research on dermatological and cosmetic problems triggered by the disruption of skin homeostasis.

RESULTS

This study describes the neuroendocrine-immune system, skin barrier structure, and skin metabolic system that maintain skin homeostasis. In addition, we discuss several common symptoms that occur when skin homeostasis is out of balance, such as dryness, redness, acne, sensitivity, and aging, and explain the mechanism of these symptoms.

CONCLUSION

This article provides an update and review for students and practitioners, and provides a theoretical basis for the development of skin care products for the maintenance and repair of skin homeostasis.

Impacts of Skin Eccrine Glands on the Measured Values of Transepidermal Water Loss

Transepidermal water loss (TEWL) is widely used to assess and quantify skin insensible water loss to assess skin's barrier function integrity. Low TEWL values are normally indicative of intact skin and a healthy functional barrier, whereas an increased TEWL reveals a disturbed or disrupted skin barrier. Because most skin sites at which these measurements are made have eccrine glands present, the contribution of the sweat gland activity to these measurements is variable and, in most cases, unknown. The separation between the contribution of water loss that is reflective of the skin barrier integrity versus that contributed via eccrine activation is not easy and is made more difficult since both components increase with increasing skin and environmental temperature. Endogenous factors that impact eccrine sweat gland activity include sympathetic nervous system activity, emotional stress, physical activity, eccrine gland density, and age. Exogenous factors that impact eccrine gland activity include ambient temperature and humidity and the climate where one resides. The aforementioned variables impact eccrine gland activity positively or negatively and therefore alter TEWL values accordingly. Although it may be theoretically possible to control all these factors, the difficulty in doing so results in only a few being controlled during most TEWL measurements. Such confounding processes may have impacted historical TEWL reference ranges and values previously reported. Thus, the impact of eccrine activation on standardly measured TEWL values is at this juncture unclear and may be a component contributing to some reported variability in TEWL values. To help clarify the issues, a literature review was conducted to investigate and summarize relevant prior research efforts and outcomes with respect to ways to consider eccrine activity in TEWL measurements and estimate the contribution of eccrine gland activity to TEWL values. Online databases such as Excerpta Medica Database (EMBASE), Public/Publisher Medline (PubMed), Elton B. Stephans Company (EBSCO), Google Scholar, and Wiley Online Library were searched with "transepidermal water loss" or "TEWL" in the title combined with "eccrine glands" or "sweat" anywhere in the text. The present findings indicate a multiplicity of biological and environmental variables impacting eccrine gland activity and thereby potentially affecting measured TEWL values. Even if laboratory conditions adhere to various guidelines and recommendations, it is not yet possible to separate the eccrine activation component from the parameter of true interest in the assessment of the skin's physiological barrier function except for full gland deactivation. The amount that such eccrine gland activation impacts the measured value of TEWL is generally not determined using currently available methods and the only sure way to eliminate a confounding effect is to inactivate the glands during such TEWL measurements. Because such eccrine gland deactivating approach is not usually desirable or even possible, other approaches would be recommended. One would be the development of a measuring device that could distinguish between the component of TEWL that is associated with the skin barrier function and the other that is attributable to sweat gland activation. Further research and development along these lines appear warranted.

hMSC exosomes as a novel treatment for female sensitive skin: An in vivo study

Background: Recent studies have reported that the incidence of sensitive skin is increasing. Skin sensitivity and skin barrier functions were related to many skin diseases including atopic dermatitis, psoriasis, rosacea, and so on. Mesenchymal stem cell (MSC)-derived exosomes (hMSC) might be considered as a new effective therapeutic scheme.

Aims: This study aims to investigate the safety and efficacy of hMSC exosomes as a novel topical treatment for sensitive skin.

Patients/Methods: Exosomes were extracted from primary hMSC via ultracentrifugation method. The morphology of hMSC exosomes was studied via transmission electron microscope. Expression of exosome specific surface marker was detected via Western blot. 22 subjects (female, aged 18–55) diagnosed with sensitive skin were enrolled. Follow-up was conducted before, 7-day, 14-day, and 28-day after hMSC exosomes use. Transepidermal water loss (TEWL), surface hydration, sebum secretion, and L*a*b* value were simultaneously tested at the same time point in an environment-controlled room.

Results: Under transmission electron microscopy, the extracted hMSC exosomes were circular or elliptical with intact membrane structure, and their diameters ranged mainly from 40 to 80 nm. Western blot showed that the expression of markers CD63, CD9, and Tsg101 was positive. Brownian motion based nanoparticle trajectory analysis (NTA) showed that the main peak of particle size distribution occurred around 96 nm, the average particle size was 122 nm, and the main peak accounted for 96.7%. All this conformed to the biological characteristics of exosomes standardized by the International Society for Extracellular Vesicles. In the clinical trial, scores of objective symptoms including roughness, scales, erythema, and subjective symptoms including tension, burning, or itching, were improved after 7-, 14-, and 28- day using hMSC-exosomes. TEWL, hydration, sebum, pH, and a* values were tended to return to the level of healthy skin.

Conclusion: The hMSC-exosomes, with the advantages of biocompatibility and biodegradability, could improve clinical symptoms and eruptions in sensitive skin patients, and might be as an MSC cell-free novel therapy in sensitive skin-related disease treatment.

Topical non-pharmacological treatment of eczema: an Italian consensus

Eczematous diseases (contact dermatitis, atopic dermatitis, hand eczema) are among the most frequent findings in dermatological clinical practice. A large body of evidence exists on structural and functional skin barrier damage in eczematous diseases, and on the importance of interventions aimed to repair such damage. While there is substantial agreement on pharmacological treatment, more sparse data are available on role, indications and usefulness of topical non-pharmacological treatments, despite significant research and progress in the composition and technology of emollients, cleansers and barrier creams significantly changed and expanded the functional activities of these products. This often leads to inadequate prescription and/or use, which increase individual and social costs of the disease and make the products useless or, in some cases, even counterproductive. This consensus document, discussed and compiled in a series of meetings by a group of Italian dermatologists experienced in the field of eczematous diseases, summarizes epidemiology and clinical features of the nosological entities of the "eczema family", illustrates the chemical/biochemical structure of emollients, cleansers and barrier creams, and aims to help physicians to exploit the full potential of available products, by providing a detailed but practical guide on characteristics, indications and correct use of non-pharmacological treatments currently available for eczematous diseases.

Psychological Aspects of Sensitive Skin: A Vicious Cycle

Sensitive Skin Syndrome (SSS) has been the subject of intense research in the past several years. Recent reviews confirm that about 40% of the population report moderate or very sensitive skin, and an additional 30% report slightly sensitive skin. Although certain phenotypes are more susceptible, anyone can suffer from SSS and this condition can manifest in all anatomic sites. A wide variety of environmental and lifestyle factors can trigger SSS symptoms of itching, stinging, burning, pain, and tingling. In order to avoid such triggers, the SSS individuals often alter their behaviors and habits such as restricting their daily activities, and modifying the use of everyday products that non-sensitive individuals take for granted. In addition, there is an association between SSS and some common psychological problems. Sensitive skin symptoms such as itching, stinging, burning and pain can result in sleep disorders, fatigue, stress and anxiety. Conversely, lack of sleep and stress from external sources can make the SSS sufferer more prone to the symptoms. This becomes a vicious cycle that impacts consumers’ quality of life and well-being. We are beginning to understand the importance of the underlying causes that can impact skin conditions. However, in order to better understand the SSS individual, we need to also be aware of the psychological factors that can trigger and/or worsen this skin condition, as well as the psychological stresses the condition places on the individual.

Irritant Contact Dermatitis — a Review

Purpose of Review

Recent Findings

Summary

Understanding the Sensitive Skin Subject to Achieve a More Holistic Diagnosis

Sensitive skin Syndrome (SSS) is a complex global clinical phenomenon that is defined by the self-reported presence of different sensory perceptions, including tightness, stinging, burning, tingling, pain and pruritus and often without objective signs. Due to the subjective nature of this clinical condition, the diagnosis is complex and there is often a disconnect between what subjects feel and what medical professionals can observe. This chapter reviews the known underlying physiology, some of the triggering factors associated with SSS, co-morbidities as well as the psychological impact on individuals suffering from this condition. The goal is to bridge the gap between the physicians’ understanding and the subjects’ perceptions of this real-life condition that affects so many.

Unbearable transepidermal water loss (TEWL) experimental variability: why?

Despite the wide breadth of research, much disparity exists in transepidermal water loss (TEWL) research data-possibly due to uncontrolled experimental variables. We determined whether such experimental variables significantly impact TEWL studies and cause this disparity. An initial literature search regarding TEWL was performed to determine potential confounding variables. A subsequent search procured relevant and representative studies investigating the impact of these variables on TEWL. Variables, such as age, anatomic site, and temperature, impact TEWL and should be controlled for in TEWL studies. Other variables, such as smoking and menstrual cycle, have inconclusive results or do not provide sufficient data breadth to make a conclusion regarding its effect, if such an effect exists, on TEWL metrics. Therefore, these variables require further research to determine their potential impact on TEWL. Matching for as many experimental variables as possible may reduce the disparity in TEWL data/conclusions.

Anatomical location differences in sodium lauryl sulfate‐induced irritation

Linked Article: https://doi.org/10.1111/bjd.17633.

Diagnosis and Treatment of Sensitive Skin Syndrome: An Algorithm for Clinical Practice

Sensitive skin has traditionally been viewed as a cosmetic problem or as a purely psychosomatic alteration with a major subjective component. Different studies of its pathophysiologic etiology, however, have shown it to be a complex entity that several authors now consider to be a neurodermatological syndrome. Because of this complexity, skin sensitivity can be difficult to diagnose and treat, particularly considering that it may present with another disease. Simple tools applicable to clinical practice are thus necessary to identify and manage this disease as an independent entity. In this study, we perform a practical review of the most recent scientific advances in the area of sensitive skin that justify it being considered an individual entity, and provide tools for its identification and treatment. We propose diagnostic and treatment algorithms based on evidence from the literature and our experience and expertise.

The Prevalence of Sensitive Skin

Sensitive skin has been described as unpleasant sensory responses to stimuli that should not provoke such sensations. Objectively measurable signs of irritation are not always present in individuals with sensitive skin, however, subjective sensory effects such as, itching, burning, stinging, tightness, and dryness, are consistently present. Given the subjective nature of the phenomenon known as sensitive skin, surveys have been a popular approach to evaluating the prevalence of this condition among the general population, and a number of them have been conducted worldwide. Overall, ~60–70% of women and 50–60% of men report having some degree of sensitive skin. However, there are differences between populations in various geographies, and perceptions of sensitive skin at specific anatomic sites. This article is a review of survey data on the prevalence of self-declared sensitive skin in various geographies, among different gender and age groups, and at various anatomic sites. In addition, we review the factors that may contribute to sensitive skin, and the physiological characteristics associated with this condition, including impaired barrier function and heightened neural reactions.

Sensitive Skin in the Genital Area

When evaluating sensitive skin, it is common to focus on the face. However, it is becoming increasingly clear that individuals can have different perceptions about the degree of skin sensitivity at distinct anatomic sites. Structural variations in the skin of different body sites can contribute to differences in barrier function, which may contribute to differences in skin sensitivity. Potential triggering factors for skin sensitivity would be expected to vary by body site. For example, the face is exposed to all ambient environmental conditions in the course of daily life, and to several products (e.g., cosmetics for women) and practices (e.g., shaving for men) that may lead to adverse sensations associated with sensitive skin. In contrast, the skin of the genital area is protected from ambient environmental conditions. However, the genital area can be exposed to conditions of higher temperature, different habits and practices and moisture due to the semi-occlusive environment. For some individuals, additional challenges such as incontinence can provide triggering factors for skin sensitivity that effect only the genital area. This article reviews data on the perception of sensitive skin of the genital area, differences based on gender, age, racial differences, and the effects of incontinence on skin sensitivity. The effects of menopause are also considered with regards to sensitive skin perceptions and to emerging differences in biomolecular and physical measures of the urogenital skin.

Skin subtype categorization based on a new questionnaire for Korean women

BACKGROUND

Several terms have been used to characterize skin types. However, these are not based on evident dermatologic definitions, which usually include subjective and psychological properties.

OBJECTIVE

The objective of this study is to establish a new practical questionnaire to classify skin subtypes in Korean women to establish treatment and skin care guidance.

METHODS

Eight experts developed consensus statements about skin types and created a questionnaire. The content was categorized into four major subtypes: dry or non-dry; oily or nonoily; sensitive or nonsensitive; and pigmented or nonpigmented. A total of 512 patients completed the questionnaire. Correlations with age, skin Fitzpatrick's phototypes, and dermatologic comorbidities were analyzed.

RESULTS

Korean women commonly have oily skin but complain of dryness after cleansing. They are especially sensitive to skin care products and prone to developing pigmentary lesions. There was a trend in the proportion of dry skin subtype that increased as pigmented skin increased and oily skin decreased with advanced age. The proportion of sensitive skin was higher in patients with dermatologic comorbidities. The proportion of the pigmented skin was higher in darker Fitzpatrick skin phototypes.

CONCLUSION

This is the first questionnaire established for Korean women to classify practical skin subtypes and may provide a basis for treating various skin conditions.

Assessment of the efficacy of a new complex antisensitive skin cream

BACKGROUND

Sensitive skin is frequently complaint in dermatology consultation with cutaneous manifestations such as stinging, redness, dryness, and burning sensation that affect the quality of life. Its pathogenesis is mainly related to dysfunction of neurosensory, skin barrier, and also immune activity. The treatment is generally based on continuous and topical therapy by nonirritating complex.

OBJECTIVE

To evaluate the antisensitive function of a new complex cream composed by Yunnan Portulaca oleracea extract, Prinsepia utilis oil, beta-glucan, and sodium hyaluronate extracted from mushroom.

METHODS

A randomized double-blind and self-control study was conducted on 20 selected volunteers with sensitive skin. Subjects applied the test cream to 1 side of the face, and the control cream (tolerance-extreme cream) to the other side of the face, twice daily over 28 days. Evaluations were performed at baseline and at 28 days. Expert clinical grading of facial skin including dryness, roughness, desquamation, and erythema was assessed. Subject self-assessment questionnaires, digital photography and noninvasive bioinstrumentation of hydration, transepidermal water loss, lipid index, skin texture, and wettability were also included in the study.

RESULTS

Products were well tolerated. For all parameters studied, no significant difference was observed between test and control creams. Results showed that test cream provided a statistically significant improvement in clinical grading scores for dryness, roughness, and erythema at 28 days compared to baseline. In addition, statistically significant improvement of skin hydration and texture parameters (eg, smoothness and roughness) was demonstrated. Volunteers' questionnaire revealed self-perceived benefits consistent with expert visual grading.

CONCLUSION

This study confirmed the effectiveness and tolerance of the new complex cream in subjects with sensitive skin. The test cream could serve as a daily care moisturizer for face.

The Scourge of the Spurge Family-An Imitator of Rhus Dermatitis

The Euphorbiaceae family (commonly known as "spurge") is a large, diverse, and widely distributed family of plants that encompass around 300 genera and more than 8000 species. Their attractiveness and hearty nature have made them popular for both indoor ornamentation and outdoor landscaping. Despite their ubiquity, the potential to cause irritant contact dermatitis (ICD) is often overlooked in favor of more notorious causes of phytodermatitis, namely, Toxicodendron species and nettles. We examined case reports spanning 40 years and discovered that spurge-induced ICD tends to befall children and middle-aged adults who unwittingly encounter the plant through play or horticulture, respectively. Clinical presentation is pleomorphic. Erythema, edema, burning, vesicles, and pruritus of acute onset and rapid resolution are frequently observed. We present a classic case of ICD in a 12-year-old girl after exposure to Euphorbia myrsinites and review the literature on phytodermatitis caused by members of the Euphorbiaceae family.

Sensitive skin

Sensitive skin is a clinical condition defined by the self-reported facial presence of different sensory perceptions, including tightness, stinging, burning, tingling, pain and pruritus. Sensitive skin may occur in individuals with normal skin, with skin barrier disturbance, or as a part of the symptoms associated with facial dermatoses such as rosacea, atopic dermatitis and psoriasis. Although experimental studies are still pending, the symptoms of sensitive skin suggest the involvement of cutaneous nerve fibres and neuronal, as well as epidermal, thermochannels. Many individuals with sensitive skin report worsening symptoms due to environmental factors. It is thought that this might be attributed to the thermochannel TRPV1, as it typically responds to exogenous, endogenous, physical and chemical stimuli. Barrier disruptions and immune mechanisms may also be involved. This review summarizes current knowledge on the epidemiology, potential mechanisms, clinics and therapy of sensitive skin.

Prevalence of and Risk Factors for Skin Diseases Among Army Personnel and Flood Victims During the 2011 Floods in Thailand

OBJECTIVE

This study aimed to determine the prevalence of and risk factors for skin problems among flood victims and army personnel during the 2011 floods in Thailand.

METHODS

To determine the prevalence of and risk factors for skin symptoms, standardized questionnaires were used to collect demographic data, current skin symptoms, history of water exposure, and sanitary behaviors. A certified dermatologist evaluated those who presented with skin problems and provided diagnoses. Univariate and multivariate analyses were performed to assess independent risk factors for skin symptoms.

RESULTS

The most prevalent skin disease was irritant contact dermatitis. Flood victims showed a higher prevalence of skin symptoms compared with army personnel. Development of skin symptoms after exposure to floodwater was also observed earlier among flood victims. Having a history of skin diseases and delayed skin cleaning after exposure were also significant risk factors for the development of skin symptoms.

CONCLUSION

This information might be used as guidelines for protecting military personnel and to educate the general public regarding flood disaster management. (Disaster Med Public Health Preparedness. 2016;10:570-575).

Wet-work Exposure: A Main Risk Factor for Occupational Hand Dermatitis

Wet-work can be defined as activities where workers have to immerse their hands in liquids for >2 hours per shift, or wear waterproof (occlusive) gloves for a corresponding amount of time, or wash their hands >20 times per shift. This review considers the recent literature on wet-work exposure, and examines wet-work as a main risk factor for developing irritant contact dermatitis of the hands. The aim of this paper is to provide a detailed description of wet-work exposure among specific occupational groups who extensively deal with water and other liquids in their occupations. Furthermore, it highlights the extent and importance of the subsequent adverse health effects caused by exposure to wet-work.

Sensitive skin: an overview

Sensitive skin is a condition of subjective cutaneous hyper-reactivity to environmental factors. Subjects experiencing this condition report exaggerated reactions when their skin is in contact with cosmetics, soaps and sun screens, and they often report worsening after exposure to dry and cold climate. Although no sign of irritation is commonly detected, itching, burning, stinging and a tight sensation are constantly present. Generally substances that are not commonly considered irritants are involved in this abnormal response.Sensitive skin and subjective irritation are widespread but still far from being completely defined and understood. A correlation between sensitive skin and constitutional anomalies and/or other triggering factors such as occupational skin diseases or chronic exposure to irritants has been hypothesized. Recent findings suggest that higher sensitivity can be due to different mechanisms. Hyper-reactors may have a thinner stratum corneum with a reduced corneocyte area causing a higher transcutaneous penetration of water-soluble chemicals. Alterations in vanilloid receptors and changes in neuronal transmission have been described. Monitoring skin parameters such as barrier function, proclivity to irritation, corneocyte size and sensorial transmission can also be useful to identify regional differences in skin sensitivity.

Irritant contact dermatitis: effect of age

Knowledge on age-relationship to irritant contact dermatitis (ICD) remains of interest. We searched for articles and textbooks on age-relationship to ICD and evaluated relevant data. Irritant response may be enhanced in children and decline with increasing age. In general, older skin reacts more slowly and with less intensity to irritants when compared with young skin. Such age-related changes may depend: (i) on differences in percutaneous penetration in old and young skin, and/or on (ii) differences in the microcirculatory efficiency, which serves as the route by which inflammatory cells make their way to the site of inflammation. Additionally, stratum corneum turnover time increases with age which means that an irritant remains longer on the skin; a compromised cutaneous blood vessel network with ageing may lead to a decreased inflammatory response, decreased absorption and decreased clearance. In conclusion, age-related differences of ICD are present despite some conflicting data. Investigations elucidating this interesting subject may benefit in prevention and intervention strategies.

Full-body skin mapping for six biophysical parameters: baseline values at 16 anatomical sites in 125 human subjects

BACKGROUND/AIM

The skin, as the outermost organ, protects against exogenous hazards (outside-in barrier) and prevents the loss of essential parts of the body (inside-out barrier). The epidermal barrier exerts several functions with specific morphological elements. Regional differences in skin functions are well known. The aim of the present study was to assess and compare skin physiological parameters in vivo at 16 anatomical sites: Barrier function in terms of transepidermal water loss (TEWL), stratum corneum (SC) hydration (assessed by capacitance), skin surface pH, skin surface temperature, erythema index and skin pigmentation were quantified at 16 anatomical sites under basal conditions. In addition, casual skin lipid level as a function of sebaceous lipids was measured on the forehead.

MATERIAL AND METHODS

The 6 functions at the 16 anatomical sites were assessed in a cohort of 125 volunteers working in the food processing industry. These functions were quantified with noninvasive instruments, namely a Tewameter (barrier function), a Corneometer (SC hydration), a pH-meter, a Mexameter (erythema index and pigmentation), a skin surface thermometer and a Sebumeter (casual sebum level).

RESULTS

We identified ranges for the 16 anatomical locations for each instrument and some parameters could be classified into distinctive groups. Furthermore, a left-right comparison was performed at 3 sites (dorsal hand, ventral hand and ventral forearm). Certain side differences could be shown for SC hydration, surface pH, erythema index, melanin index and skin surface temperature in the 3 assessed areas. A left-to-right, statistically nonsignificant difference was also established for TEWL.

CONCLUSION

The detected site-specific characteristics could be attributed to factors such as occlusion, different degrees of UV exposure, microcirculation and distribution of afferent and efferent nerve endings as well as fat distribution. External factors, such as life style, UV exposure and working conditions need to be taken into account. The present data are intended for an adequate selection of parameters and anatomical locations when assessing working conditions and designing clinical dermatological and pharmaceutical studies.

Contact dermatitis in older adults: a review of the literature

Contact dermatitis is a significant health problem affecting the elderly. Impaired epidermal barrier function and delayed cutaneous recovery after insult enhances susceptibility to both irritants and allergens. Exposure to more numerous potential sensitizers and for greater durations influences the rate of allergic contact dermatitis in this population. Medical co-morbidities, including stasis dermatitis and venous ulcerations, further exacerbate this clinical picture. However, while these factors tend to increase the degree of sensitization in the elderly, waning immunity can actually decrease such a propensity. This interplay of both intrinsic and extrinsic factors makes a generalization on trends for contact dermatitis in older adults challenging. The literature has varying reports on the overall incidence of allergic contact dermatitis with advancing age. Nevertheless, it does clearly show that sensitivity to topical medicaments increases with age. Irritant contact dermatitis studies are more consistent, with less reactivity (to irritants) in older compared with younger skin. Diagnosis of both irritant and allergic contact dermatitis is based on a thorough history, complete skin examination, and comprehensive patch testing. The mainstay of therapy is avoidance of the offending chemical substances and the use of topical along with systemic therapies, depending on the severity of the condition.

Distinct locational differences observable in biophysical functions of the facial skin: with special emphasis on the poor functional properties of the stratum corneum of the perioral region

The face is composed of complicated anatomical components, presenting unique portions, such as the eyes, nose and mouth in a relatively narrow area. Moreover, the facial skin is densely populated by the pilosebaceous units and sweat glands, and its stratum corneum (SC) is much thinner than that of the trunk and limbs, although it is always exposed to the environment. Among various portions of the facial skin, some are more easily irritated than others by environmental stimuli, or are more often affected by certain dermatoses. However, the functional aspects of the different portions of the facial skin have not been studied in detail under a strictly controlled environment in sufficiently large numbers of subjects covering different age groups. Thus, we conducted studies in winter with various biophysical techniques, such as transepidermal water loss (TEWL), as a parameter for SC barrier function, high-frequency conductance as that for skin surface hydration state, skin surface lipids, pH, blood flow and skin surface temperature on the forehead, mid-portion of the cheek (cheek in short), nasal tip (nose in short), nasolabial fold and chin of 20 healthy Japanese females aged 22-37 years (average 25 years) in a climate chamber adjusted to 21 degrees C and 50% relative humidity. Thereafter, we studied the influence of ageing on these biophysical parameters by collecting data of TEWL, high-frequency conductance and size of superficial corneocytes on the cheek, nasolabial fold and chin of 303 healthy Japanese female volunteers of different ages. The obtained results showed that the barrier function of the SC was best on the cheek, presenting the lowest TEWL, which was significantly higher on the nasolabial fold and chin than on the cheek. TEWL showed a decrease with age. In contrast, skin hydration state was higher on the nose, but it tended to be lower on the nasolabial fold, showing a mild age-related increase. The corneocytes on the nasolabial fold and chin were smaller than those on the cheek. They revealed a clear increase in size with age. Skin surface lipids were richest on the nose, whereas the superficial pH on the nose was the lowest among the regions tested. The skin temperature was lowest on the cheek than on other areas of the face; although, together with the nose, its blood flow was higher than that of the others. These data indicate great regional differences observable in SC functions on the face. In general, the SC barrier function increases with age, probably because of a decreased epidermal turnover rate as recognized by the increase in corneocyte size. Among the various sites, the skin of the nasolabial fold and chin, whose SC consisted of the smallest corneocytes, showed poorest SC properties in barrier function, suggesting the presence of mild invisible inflammation. It is understandable that this area easily develops not only the complaint of sensitive skin to cosmetics but also dermatitis because of various external agents.

Caffeine improves barrier function in male skin

The influence of androgens, especially testosterone and its effector dihydrotestosterone, results in a constitutive disadvantage for male skin, e.g. reduced viability of hair at the scalp and reduced epidermal permeability barrier repair capacity. Dihydrotestosterone can act, among others, as an adenyl cyclase inhibitor. Caffeine on the other hand is an inexpensive and (in regular doses) harmless substance used in various cosmetic products, which can act as a phosphodiesterase inhibitor. To prove the hypothesis that caffeine as a phosphodiesterase inhibitor is able to override testosterone-induced effects on barrier function, we performed a double-blind placebo controlled study with healthy volunteers. In this study, 0.5% caffeine in a hydroxyethylcellulose gel preparation (HEC) was applied on one forearm, HEC without caffeine on the other forearm of male and female volunteers for 7 days and transepidermal water loss (TEWL) was measured before and at the end of the treatment period. Basal TEWL did not differ significantly between male and female subjects but the application of caffeine significantly reduced TEWL in male skin compared with female skin. We conclude that caffeine is beneficial for barrier function in male skin.

Percutaneous absorption and exposure assessment of pesticides

Dermal exposure to a diverse range of chemicals may result from various uses. In order to assess exposure and estimate potential risks, accurate quantitative data on absorption are required. Various factors will influence the final results and interpretations of studies designed to assess the ability of compounds to penetrate the skin. This overview will discuss skin penetration by pesticides, emphasizing key parameters to be considered from the perspective of exposure assessment.

Chronic Pain of the Vulva without Dermatologic Manifestations: Distinguishing among a Spectrum of clinical Disorders

The causes of chronic vulvar pain are many and when not accompanied by obvious physical signs they are difficult to unravel. Many common vulvar dermatoses can manifest without obvious erythema or mucocutaneous lesions, as can some less common disorders of both infectious and allergic origin. In addition localized and generalized vulvar dysesthesia, recently defined chronic pain syndromes of neurogenic origin, can also occur in the vulvar area.

Chronic vulvovaginal symptoms in early stages are often presumptuously labeled as vulvovaginal candidiasis (VVC) by patients and clinicians alike, which can delay accurate diagnosis. When presented with chronic vulvar pain unaccompanied by verifiable signs, the clinician must effect a sensitive integration of a detailed medical history, including temporal associations of all potential exposures, with more definitive diagnostic tools. Effective use of those available tools can improve initial diagnosis, thus allowing prompt initiation of effective therapy. Optimal therapy will recognize the significant psychological distress that accompanies any chronic pain syndrome.