Population differences in acute skin irritation responses. Race, sex, age, sensitive skin and repeat subject comparisons

The association between wet work and hand eczema in the Dutch general population: Application of a job exposure matrix to the lifelines cohort study

BACKGROUND

Studies on wet work and hand eczema (HE) frequently rely solely on self-reports regarding wet work.

OBJECTIVES

To assess the association between wet work and moderate-to-very-severe HE, within the Dutch general population, by using a (sex-specific) job exposure matrix (JEM).

METHODS

Within the Lifelines Cohort Study, participants with self-reported moderate-to-very-severe HE at worst in the past year were linked to data from the Danish (sex-specific) wet work JEM, a tool that links occupations with wet work indices (including duration and probability of glove use, wet hands and total wet work for at least 2 and 4 h/working day).

RESULTS

In total, 56 978 (41.9%) participants were included. The multivariate binary logistic regression analyses showed significant associations between all facets of wet work and moderate-to-very-severe HE. When using the sex-specific JEM, significant associations were found in females, but not in males.

CONCLUSIONS

This study is the first to use a wet work-specific JEM in a general population sample, and found positive associations between wet work and HE. The sex-specific findings should be interpreted with caution, due to limitations inherent in using a JEM, and should be further explored with observational studies, with a focus on duration, frequency, and exposure type.

Toxicological evaluation of a nonlethal riot control combinational formulation upon dermal application using animal models

Numerous adverse effects on human health have been reported in epidemiological studies of oleoresin capsicum (OC) and other riot control agents (RCAs). Importantly, the daunting risk of such RCAs can be neutralized by optimizing the desired concentration of such agents for mob dispersal. Hence, a nonlethal riot control combinational formulation (NCF) was prepared for dispersing rioters without imparting fatal outcomes. However, for desired utilization of NCF, it is essential to recognize its extent of potential toxicity. Therefore, the current investigation evaluated the dermal toxicity of NCF using experimental animals in compliance with the OECD guidelines. Additionally, few essential metal ions were analyzed and found non -significantly different in the test rats as compared to control rats. Moreover, abnormal dermal morphology and lesions ultrastructural tissue defects were not noticed as evinced by different studies like ultrasonography, histology, and scanning electron microscopy (SEM) respectively. Further, Doppler ultrasonography exhibited non-significantly different blood flow velocity in both groups, whereas miles test demonstrated a significantly increased Evans blue concentration in test rats compared to the control rats, which might be due to an initial increase in blood flow via an instant action of the NCF at the cutaneous sensory nerve endings. However, our results demonstrated NCF can produce initial skin irritating and sensitizing effects in guinea pigs and rabbits without the antecedence of acute toxicity (≤2000 mg/kg) in Wistar rats.

The Challenges in Investigating the Pathogenesis of Sensitive Skin by Noninvasive Measurements: A Systematic Review

Sensitive skin (SS) is a common cutaneous condition that seriously affects people's quality of life, but studies of sensitive skin pathogenesis are unclear, the exploration are ongoing, and the biophysical properties of sensitive skin disagree with the study results. In this paper, we summarize the noninvasive biophysical and imaging instrumental methods used for sensitive skin and provide support for the classification of sensitive skin subtypes to prescribe precise treatment. PubMed and Web of Science databases were searched according to PRISMA guidelines for articles from January 1971 to May 2022 that used noninvasive biophysical or imaging methods to monitor adult subjects with sensitive skin. The quality of the included articles was determined based on 22 items of the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) statement. A total of 55 studies were included, representing 8 biophysical and 5 imaging methods and their applications in treatment efficacy evaluation studies. The biophysical parameter and cutaneous morphological property changes in sensitive skin subjects were observed. The quality of the studies was relatively low, and there was high variability in results between studies. Several parameters have shown tremendous potential in exploring the pathogenesis with different sensitive skin subtypes: type I may be detected with higher transepidermal water loss and lower stratum corneum hydration values, as well as with thinner epidermis with a shallower and more irregular honeycomb structure; Type II and III are more prone to higher blood flow, lower current perception threshold than normal skin. This systematic review identifies key reasons for the lack of uniform trends in noninvasive measurements and recommends the use of effective selection instruments or relevant parameters to explore the pathogenesis of sensitive skin, and to differentiate the subtypes of sensitive skin for achieving the precise treatment.

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

Sensitive skin: Active ingredients on the spotlight

OBJECTIVE

Sensitive skin is characterized by self-reported sensory perceptions in response to stimuli that should not provoke unpleasant sensations. Cosmetic products for sensitive skin are designed to minimize these symptoms. This study aimed to unveil the most used active ingredients for sensitive skin in facial care products from the pharmacy and parapharmacy channel.

METHODS

A pool of products from the pharmacy and parapharmacy channel whose label included the expressions 'sensitive skin', 'reactive skin' or 'intolerant skin' were analysed. The active ingredients were identified from product compositions and ranked in descending order of occurrence. The scientific evidence regarding the mechanism of action and efficacy of each ingredient was also compiled.

RESULTS

Eighty-eight products from 19 multinational brands were included. Niacinamide leads the top, followed by Avena sativa, allantoin, glycyrrhetinic acid and derivatives and Laminaria ochroleuca. Ingredients that can reduce skin inflammation and act on the skin barrier were used in more than half of the products analysed. The clinical studies regarding the active ingredients used in these products remain sparse and lack methodological quality. Among the top ingredients, niacinamide, panthenol and acetyl dipeptide-1 cetyl ester were the only ones studied on volunteers having sensitive skin, while acetyl dipeptide-1 cetyl ester and palmitoyl tripeptide-8 were designed to act on the molecular targets involved in this condition.

CONCLUSION

This study reveals the most used active ingredients in cosmetic products for sensitive skin, as well as the scientific evidence supporting their efficacy and the mechanisms of action. This insight is meaningful for dermatologists and other health professionals to provide customized advice based on the symptomatology of individuals with sensitive skin, and for the formulation of cosmetic products and design of new active ingredients.

A Survey to Identify Determinants That Influence Self-Perceived Sensitive Skin in a British Population: Clues to Developing a Reliable Screening Tool for Sensitive Skin

Background

Skin sensitivity characteristics and triggers have been identified in populations in previous studies. However, few have compared these characteristics among self-reported sensitive skin.

Objective

The aim of the study was to evaluate and compare specific intrinsic and extrinsic triggers of skin sensitivity between individuals with self-reported sensitive skin and non-sensitive skin.

Methods

A systematic literature review was undertaken to identify intrinsic and extrinsic factors associated with sensitive skin. A 167-item survey was developed on the basis of the literature review. The survey was completed online by a sample of adult participants drawn from the general United Kingdom population. Participants also completed sociodemographic and self-reported health questions.

Results

A total of 3050 surveys were completed: 1526 participants with self-reported skin sensitivity and 1524 participants not reporting skin sensitivity. There was a decrease in self-reported skin sensitivity with increasing age (p<0.05), and proportionally more women reported sensitive skin. Smoking also led to a higher frequency of sensitive skin. All signs and symptoms of sensitive skin, such as itch, dryness/flakiness, roughness and flushing/blushing were more commonly reported by those with self-reported sensitive skin. These were frequently reported in association with external factors (cold/windy weather, clothes and fabrics), as well as internal factors such as pre-existing skin conditions and atopy.

Conclusion

The study evaluated self-reported sensitive skin against a non-sensitive skin in order to identify common inherent and external triggers to distinguish between these groups in a large general population study in the United Kingdom. The key symptoms and signs of this syndrome identified in the literature were confirmed to be reported significantly more when compared with those without sensitive skin. However, no correlation or pattern of symptomology could be identified, reinforcing the complexity of this condition. Given the strong differentiation from the non-sensitive group, the results of this research could be utilised for the development of a clinically meaningful screening tool.

Influence of Ethnicities and Skin Color Variations in Different Populations: A Review

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.

Nationwide Survey and Identification of Potential Stress Factor in Sensitive Skin of Chinese Women

Purpose

Sensitive skin is characterized by uncomfortable sensations in response to a number of factors. We performed a large-scale study to investigate the prevalence of sensitive skin at all ages and the impacts of related factors across China.

Methods

A nationwide sampling of the Chinese population aged over 18 was conducted. Subjects were categorized into sensitive and non-sensitive groups, and critical differences between these two groups were investigated.

Results

In total, 22,085 questionnaires were collected from Chinese women with sensitive skin. The prevalence of sensitive skin is 49.6% and is associated with age, skin type, geographic area of subjects, and other factors. Heavy life stress and the application of several cosmetic products also affect the prevalence of sensitive skin.

Conclusion

Having a combination or oily skin type, living in the municipalities, being under heavy stress, and applying several cosmetic products will increase skin stress and contribute to the occurrence of sensitive skin.

Have We Just Scratched the Surface? A Narrative Review of Uremic Pruritus in 2020

Purpose of review:

Uremic pruritus is a highly prevalent and debilitating symptom in patients with chronic kidney disease (CKD) and end-stage kidney disease (ESKD). The purpose of this review is to examine current evidence on the mechanisms and treatments of pruritus in CKD and highlight promising areas for future research.

Sources of information:

Published literature, including randomized controlled trials, cohort studies, case reports, and review articles, was searched for evidence pertaining to the pathophysiology and treatment of uremic pruritus.

Methods:

A comprehensive narrative review was conducted to explore the molecular mechanisms underlying uremic pruritus, as well as the evidence (or lack thereof) supporting pharmacological and nonpharmacological treatments for uremic pruritus. The potential role of patient sex in the pathophysiology and management of uremic pruritus is also discussed.

Key findings:

The pathophysiology of uremic pruritus involves a complex interplay of uremic toxins, systemic inflammation, mast cell activation, and imbalance of opioid receptors. Classic treatment strategies for uremic pruritus include optimization of dialysis parameters, amelioration of CKD-related mineral and bone disease, topical emollients and analgesics, antihistamines, the anticonvulsant medications gabapentin and pregabalin, and ultraviolet light B (UV-B) phototherapy. Strong data to support many of these classical treatments for uremic pruritus are limited. Newly evolving treatment approaches for uremic pruritus include opioid receptor modulators, neurokinin-1 inhibitors, and cannabinoids. Further studies regarding their efficacy, pharmacodynamics, and safety in the CKD and ESKD population are needed before these agents are accepted into widespread use. Additional nonpharmacological strategies aimed at treating uremic pruritus include psychotherapy, acupuncture, omega-3 fatty acids, and exercise. Finally, sex differences may exist regarding uremic pruritus, but studies directly addressing sex-specific mechanisms of uremic pruritus remain absent.

Limitations:

High-quality evidence in the management of uremic pruritus remains lacking. Most recommendations are based on expert opinion or studies involving small numbers of patients. In addition, our understanding of the pathophysiological mechanisms behind uremic pruritus is incomplete and continues to evolve over time.

Implications:

Uremic pruritus is a common symptom which reduces quality of life in CKD and ESKD. The identification of novel targeted treatment approaches may ease the burden of uremic pruritus in the future.

Plant Complexity and Cosmetic Innovation

Plants have been used in cosmetic products since ancient times and are the subject of scientific investigation even nowadays. During the years, a deeper understanding of both the behavior of skin and of plants have become available drawing increasingly complex pictures. Plants are complex organisms that produce different metabolites responding to the environment they live in. Applied to the skin, phytomolecules interact with skin cells and affect the skin well-being and appearance. Ethnobotanical studies on the one hand and physico-chemical analyses on the other have pictured a rich inventory of plants with potential to enrich modern cosmetic products.

Challenging a paradigm: skin sensitivity to sodium lauryl sulfate is independent of atopic diathesis

BACKGROUND

Sodium lauryl sulfate (SLS) is the best-studied detergent in irritant contact dermatitis. In atopic dermatitis, the two major pathophysiological abnormalities concern skin barrier function and regulation of cutaneous immune responses. The probability of atopic skin diathesis can be assessed by comprehensive analysis of patient history, as well as clinical and laboratory findings, resulting in the Erlangen Atopy Score (EAS).

OBJECTIVES

To investigate the impacts of (i) atopic skin diathesis according to the EAS and (ii) the physician-assessed diagnoses 'atopic dermatitis', 'allergic rhinitis' and 'allergic asthma' on SLS skin reactions.

METHODS

This is a retrospective analysis of data from 2030 consecutive patients patch tested with SLS (0·25% aqueous) from two tertiary referral centres in Germany, from 2008 to 2014.

RESULTS

Patients with a high probability of atopic skin diathesis showed no significant increase in positive SLS reactions compared with patients without atopic skin diathesis (14·2% vs. 16·8%). The grading of positive SLS skin reactions (1-4) revealed no differences in patients with or without atopic skin diathesis. Furthermore, diagnoses of atopic dermatitis, allergic rhinitis or allergic asthma had no impact on positive SLS skin reactions in multivariate logistic regression analysis.

CONCLUSIONS

We found no association of increased skin irritability to SLS with atopic skin diathesis, atopic dermatitis, allergic rhinitis or allergic asthma in a large patient cohort. It therefore seems that the test of skin irritability with SLS, which is currently common practice in many centres, does not allow prediction of susceptibility to irritant eczematous inflammation in atopic vs. nonatopic individuals. What's already known about this topic? Irritant contact dermatitis and atopic skin diathesis share impaired skin barrier function as a pathophysiological pattern. Sodium lauryl sulfate (SLS) is tested at 0·25% aqueous as an irritant control in patch testing, and hence the results might be affected by atopic skin diathesis. What does this study add? Challenging a long-standing paradigm, we found no association of increased reactivity to SLS patch tests in individuals with atopic skin diathesis, atopic dermatitis, allergic rhinitis or allergic asthma in a large patient cohort. Thus, irritant control testing with SLS, which is useful in interpreting doubtful allergen patch test results, does not depend on individual atopy status.

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.

Sensitive skin is highly frequent in extrinsic atopic dermatitis and correlates with disease severity markers but not necessarily with skin barrier impairment

BACKGROUND

Sensitive skin is a condition of cutaneous hypersensitivity to environmental factors. Lactic acid stinging test (LAST) is commonly used to assess sensitive skin and composed of four distinct sensations (pain, burning sensation, itch, and crawly feeling). A link between sensitive skin and barrier dysfunction has been proposed in atopic dermatitis (AD) patients. However, clinical and laboratory factors that are associated with sensitive skin remain unelucidated.

OBJECTIVE

To investigate relationship between sensitive skin and AD-associated markers.

METHODS

Forty-two Japanese AD patients and 10 healthy subjects (HS) were enrolled. AD patients were divided into extrinsic (EAD; high IgE levels) and intrinsic (IAD; normal IgE levels) types. We conducted 1% LAST by assessing the four distinct sensations and calculated the frequencies of sensitive skin in EAD, IAD, and HS. We also performed clinical AD-related tests, including transepidermal water loss (TEWL), visual analogue scale (VAS) of pruritus, and quality of life, and measured laboratory markers, including blood levels of IgE, CCL17/TARC, lactate dehydrogenase (LDH) and eosinophil counts, and concentration levels of serum Th1/Th2 cytokines. Filaggrin (FLG) mutations were examined in 21 patients. These values were subjected to correlation analyses with each of the four sensation elements.

RESULTS

According to the standard criteria for LAST positivity, the frequencies of LAST-positive subjects were 54.8% and 10.0% in AD and HS, respectively (P=0.014). EAD patients showed a significantly (P=0.026) higher frequency of positive LAST (65.6%) than did IAD patients (20.0%). Among the four LAST sensation elements, the crawly feeling and pain scores positively correlated with VAS of pruritus, total serum IgE, mite-specific IgE, CCL17/TARC, and/or LDH. There was no association of the LAST scores with serum Th1/Th2 cytokine levels. Notably, neither TEWL nor FLG mutations correlated with LAST positivity or any sensation scores.

CONCLUSIONS

The frequency of sensitive skin is higher in EAD than in IAD. Sensitive skin is associated with AD severity, but not necessarily with barrier condition.

Treatment of Seborrhoeic Dermatitis in Asia: A Consensus Guide

Seborrhoeic dermatitis (SD) is common in Asia. Its prevalence is estimated to be 1-5% in adults. However, larger population-based studies into the epidemiology of SD in Asia are lacking, and the aetiology of SD may differ widely from Western countries and in different parts of Asia. In addition, clinically significant differences between Asian and Caucasian skin have been reported. There is a need to define standardized clinical diagnostic criteria and/or a grading system to help determine appropriate treatments for SD within Asia. With this in mind, experts from India, South Korea, Taiwan, Malaysia, Vietnam, Singapore, Thailand, the Philippines, Indonesia, and Italy convened to define the landscape of SD in Asia at a meeting held in Singapore. The consensus group developed a comprehensive algorithm to aid clinicians to recommend appropriate treatment of SD in both adults and children. In most cases, satisfactory therapeutic results can be accomplished with topical antifungal agents or topical corticosteroids. Non-steroidal anti-inflammatory agents with antifungal properties have been shown to be a viable option for both acute and maintenance therapy.

A double-blinded, randomized, vehicle-controlled study to access skin tolerability and efficacy of an anti-inflammatory moisturizer in treatment of acne with 0.1% adapalene gel

INTRODUCTION

Topical retinoids are considered to be the first-line agents and maintenance therapy of acne; however, irritation side effects are major concern issues. Noncomedogenic moisturizers are sometimes added to relieve cutaneous irritations. This study aimed to compare tolerability and efficacy of moisturizers containing licochalcone A, l-carnitine and 1,2-decanediol (active formulation) with a placebo in mild to moderate severe acne in Asian subjects.

METHODS

This was an 8-week double-blind, prospective, randomized controlled study. All patients (n = 120) were randomized equally into three groups: (A) adapalene gel, (B) adapalene gel with the active formulation and (C) adapalene gel with the placebo. The severity of acne, skin bioengineering measurements and skin tolerability were recorded during the study.

RESULTS

Compared to baseline, the active formulation group showed significant reductions in inflammatory lesions and total lesions at the end of the study without flare-up. Moreover, skin irritations were less detected than in the other two groups by corneometer and transepidermal water loss measurements.

CONCLUSIONS

The concomitant usage of adapalene gel and the moisturizer containing licochalcone A, l-carnitine and 1,2-decanediol could reduce undesirable side effects without interfering the efficacy of adapalene. This moisturizer may be superior to placebo to prevent cutaneous irritations and enhance patients' adherence to acne medications.

Skin sensitivity and intolerance in Shanghai: cumulative influence of different meteorological parameters

BACKGROUND

Although Sensitive skin (SS) conditions are reported to be affected by climate changes, the correlations with meteorological parameters remain mostly unclear.

OBJECTIVE

To investigate the changes of facial skin conditions in different seasons in Shanghai, including the speed and severity of the influences imposed by different meteorological parameters.

METHODS

Totally eighty-one healthy female volunteers completed the study in both spring (May) and summer (August). Evaluations of facial skin conditions included stimulating sensory test, clinical grading and biophysical measurements. Correlations between the meteorological parameters and ΔTEWL as well as clinical parameters were analyzed.

RESULTS

There was no significant difference between two seasons in lactic acid sting test. The stimulation sensations felt by Vitamin B3 (VB3) containing cream was significantly higher in May than that in August. In accordance, baseline visual scores for erythema and scaliness in May were also significantly higher than those scores in August. The baseline transepidermal water loss (TEWL) value was significantly higher in May than that in August. Positive correlations were detected between ΔTEWL and atmospheric pressure on the test day, adjust 3-day and 7-day mean of daily solar radiation respectively. There were negative correlations between ΔTEWL and temperature outside on the test day, adjust 3-day mean as well as adjust 7-day mean of relative humidity.

CONCLUSIONS

Facial skin conditions in summer are better than that in spring in Shanghai. The influences from atmospheric pressure and temperature are relatively quick in speed, while the influences from relative humidity and solar radiation are slow but cumulative.

Sensory and motor thresholds of transcutaneous electrical stimulation are influenced by gender and age

BACKGROUND

Transcutaneous electrical stimulation (ES) is a therapeutic procedure used in rehabilitation. However, the effectiveness of it depends on sensory responses to pain and motor control in neuromuscular recruitment, considering the differences related to gender and age of the subjects treated, as well as the intensity and frequency of ES.

OBJECTIVE

To determine the threshold of sensory perception (TSP) and the threshold of motor response (TMR) in young and elderly individuals of both genders.

DESIGN

Randomized controlled clinical trial.

SETTING

General community.

PARTICIPANTS

Eighty volunteers with no history of systemic diseases were selected to participate in the study: 40 men and 40 women were subdivided by convenience sampling and age group into young male and female (age 21.6 ± 2.4 years) groups as well as into elderly female and male groups (age 72.6 ± 6.1 years).

INTERVENTIONS

The participants received electrical stimulation (ES) at 5 and 50 Hz, with pulse durations of 20, 100, 400, 1000, and 3000 μs applied on the flexor muscle bellies of the wrist and fingers.

MAIN OUTCOME MEASURES

TSP was identified as the first sensation of increased current intensity and TMR as the minimum muscle contraction detected. The results were submitted to analysis of variance, followed by the Tukey's test, with a significance level of 5%.

RESULTS

TSP was lower than TMR for all pulse durations, regardless of gender and age. In women, TSP was lower than that in young and elderly men at both frequencies. However, TSP was higher in elderly subjects than in younger subjects at 50 Hz for both genders. Age also affected the TMR, presenting higher thresholds in elderly subjects of both genders at 50 Hz; however the same occurred only in male subjects at 5 Hz.

CONCLUSION

Age and gender interfere directly with ES. These variables should be considered during rehabilitation because they indicate that electrical stimulation in elderly women should be carefully performed, as they have lower thresholds than elderly men when polarized currents are used, and there is a risk of skin lesion because of their high thresholds.

Contact hypersensitivity: quantitative aspects, susceptibility and risk factors

The development of allergic sensitisation by environmental chemicals results in allergic contact dermatitis and highly undesirable morbidity and disability. This form of hypersensitivity is mediated by specific T lymphocytes that recognise the chemical sensitiser bound to self-proteins. Use of deliberate experimental contact sensitisation with dinitrochlorobenzene (DNCB) has been used to investigate the human immune system which exhibits dose-related responses. Many factors contribute to whether sensitisation occurs and the nature and magnitude of the immune response. Chemicals vary in sensitising potency, mainly reflecting their intrinsic protein-binding properties. The amount of sensitiser reaching the immune system is determined by many factors of which the concentration (dose per unit area), the relative lipid solubility and molecular weight are the most critical. Host-related factors contributing to the nature and magnitude of immune responses are mainly genetically determined including gender, age, the biochemical/physical integrity of the epidermal barrier and the quality of the innate and adaptive immune systems. The underlying mechanisms must be elucidated before it will be possible to make reliable predictions of whether a given individual will develop allergic sensitisation by a given chemical.

Prevalence of sensitive skin and its biophysical response in a Mexican population

AIM: To describe the frequency and biophysical response of sensitive skin in Mexican subjects, using the lactic acid test.

METHODS: The lactic acid stinging test was applied to 250 healthy volunteers, both sexes, 18 years of age or older, without any active dermatoses on the test site. Volunteers were university students, workers of public institutions, and general population from San Luis Potosi, Mexico. Participants were not excluded based on socioeconomic status. Demographic data were obtained through a questionnaire. Skin phototype was obtained through colorimetry. Subjects were randomized to receive 10% lactic acid on one nasolabial fold and placebo on the other side. The presence and intensity of adverse sensations, such as itching, burning, or stinging, was evaluated through a 10-point Visual Analogue Scale (VAS) prior to treatment and at 3, 5, 8 and 10 min after the intervention. Subjects with a VAS of 2 or higher were considered positive for the test. A VAS lower than 2 was considered a normal response to skin manipulation. Simultaneously, biophysical changes and barrier function were assessed by colorimetry, transepidermal water loss (TEWL), and capacitance. To decrease measurement variations by skin manipulation, the nasolabial fold was segmented in four areas of 1 cm² for each time measurement. Descriptive analyses were made using central tendency measures. Analyses of data were performed using two-tailed χ² test, Fisher’s test, t-test, logistic regression, or Mann-Whitney U test for non-parametric values between groups.

RESULTS: Of the included 246 subjects, 68% were women and the mean age was 32 years. The most frequent skin phototype was V (ranges II-V). Thirty-six percent of the subjects identified themselves as having sensitive skin. Fifty-two percent of the subjects were positive to the lactic acid stinging test, with a mean VAS of 4.5 at 3 min. Subjects with the self-diagnosis of sensitive skin were more likely to be positive for the test (80% vs 36%, P < 0.001). Lighter skin phototypes (types II and III) showed a higher response to the test compared to darker skin tones (type V; OR = 0.88, P < 0.001). There were no statistical differences in baseline biophysical measurements. At 3 min, TEWL was significantly higher in subjects positive to the test (27.5 vs 23.7, P < 0.05). At 5 min, TEWL and capacitance showed statistical differences (26.0 vs 22.4, P < 0.05, and 239 vs 179, P < 0.05, respectively). After 5 min, values tended to return to baseline levels in both groups.

CONCLUSION: Sensitive skin is frequent in our population. Darker skin phototypes have a lower prevalence of this syndrome, probably due to inherent differences in skin barrier function.

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.