Baseline transepidermal water loss in patients with acute and healed irritant contact dermatitis

To examine the skin harrier function of patients with acute and healed irritant contact dermatitis ( n = 80) baseline transepidermal water loss (TEWL) was quantitatively measured using an evaporimeter. Healthy subjects served as controls ( n = 40). Test areas were the forearm and the thigh. A significant increase in TCVV'L was observed in the patients with acute and with healed irritant contact dermatitis (ICD) as compared LO healthy volunteers ( P ≤ 0.01). TEWL values in both test areas were com parable and markedly correlated ( p ≤ 0.01). with each other in every group. Thus, it is possible that basal TEWL depends more on the intrinsic skin barrier function of the subjects rather than the 2 anatomical regions examined. TEWL at the forearm with acme ICD was significantly higher ( P ≤ 0.01). than that of the group with healed ICD, but not for TCWL at the thigh suggesting that ICD may aggravate the barrier function of the adjacent involved skin. It is assumed, that increased basal TEWL in patients with ICD may relied a constitutional deviation of epidermal barrier function. This event seems to be comparable with the well-known symptom of atopic individuals. Using a detailed atopic scoring system in such a study may clarify the question of whether a proportion of patients with hand ICD may indeed be atopic individuals.     

Prediction of susceptibility to an irritant response by transepidermal water loss

The roles of the natural permeability of the stratum corneum to water, and the changes in that permeability effected by a single patch test, were investigated as parameters to predict the susceptibility of the skin to repeated exposures of an irritant. One site on the forearm skin of 27 non-atopic healthy subjects was exposed to a 0.5% concentration of sodium lauryl sulphate by a single occlusive 24-h patch. Another site was exposed to a twice daily 4-day repeated occlusive patch with the same irritant solution. The effects were evaluated by transepidermal water loss measurements made prior to the applications (baseline) on day 1 (BASE), following the single 24-h patch on day 2 (SINGL), and following the 4-day repeated applications on day 5 (REPET). Individuals with higher BASE had higher SINGL (R = 0.80, P less than 0.001) and higher REPET (R = 0.76, P less than 0.001). There was also a significant linear correlation between SINGL and REPET (R = 0.63, P less than 0.001). Multiple linear regression analysis of results, however, indicated that a high baseline TEWL is better indication of an individual's increased susceptibility (high REPET) to weak irritants than a high TEWL value following a single 24-h patch test. Baseline TEWL may therefore be used as a reasonably accurate preliminary "predictive" screening test for susceptibility to irritants.     

Skin irritant reactivity following experimental cumulative irritant contact dermatitis

Despite the frequency of irritant contact dermatitis, very little is known about the duration of barrier function impairment following cumulative irritant contact dermatitis. We studied post-irritation irritant reactivity by assessing the response to SLS irritation in previously irritated sites. Cumulative irritant contact dermatitis was induced on the forearms of 15 volunteers aged 18 to 50 years by repeated occluded application of 0.5% SLS I h per day over 3 weeks. 3, 6 and 9 weeks later, previously irritated and unirritated control sites were challenged with 2% SLS under occlusion for 23 h. Irritation was assessed by visual scoring, transepidermal water loss (TEWL) as an indicator of epidermal barrier function, and capacitance as a parameter of epidermal water content. While no difference in irritant reactivity between pre-irritated and unirritated sites was observed 3 weeks following irritant contact dermatitis, there was a significant hyporeactivity of previously irritated skin as expressed by clinical scores, TEWL and capacitance at 6 and 9 weeks. Our results indicate that epidermal barrier function remains altered even 9 weeks after cumulative irritant contact dermatitis. With regard to patch testing, post-irritation hyporeactivity might be a cause of false-negative tests on previously irritated sites.     

The barrier component and the driving force component of transepidermal water loss and their application to skin irritant tests

BACKGROUND/AIM: According to Fick's law of diffusion, the rate of transepidermal water loss (TEWL) is determined by a barrier component and a driving force component. The objective of this study is to propose novel indicators for the assessment of skin irritation potential from chemicals using these components. METHODS: Before and after acetone/ether (AE), sodium lauryl sulfate (SLS) and nicotinic acid methyl ester (NME) treatments, the apparent mass transfer coefficient of water, K, of the stratum corneum (SC) and the apparent water vapor pressure, P(d), at the interface between SC and epidermis were estimated as measures of the SC barrier and the driving force, respectively. RESULTS: After AE treatment, K showed marked increase and P(d) remained approximately constant. All participants reacted to NME with erythema and the laser-Doppler flowmetry (LDF) value peaked at around 30 min. While there was a change in P(d), which parallels with LDF changes, K showed little variation. Repeated SLS treatment induced a slight increase in P(d) besides an increase in K. In the meantime, all participants reacted with subtle erythema. CONCLUSIONS: Our results suggest that not only the SC barrier but also the driving force determines variations in the TEWL rates during skin irritant tests. Together, K and P(d) will provide us with invaluable information about skin condition.     

Artificial disruption of skin barrier prior to irritant patch testing does not improve test design

BACKGROUND: Irritant patch testing is often performed as a 24- or 48-h occlusive patch test with low concentrations of sodium lauryl sulphate (SLS). OBJECTIVES: The aim of this study was to investigate potential ways to shorten this test procedure and obtain precise test results. PATIENTS AND METHODS: Thirty-six healthy volunteers underwent irritant patch testing with different pretreatments (PT) of the test fields. Occlusive test chambers were applied on the upper back with SLS 0.5%, 1%, 2% and 5% in large Finn Chambers(R). The patches were removed after 4 and 24 h, respectively, depending on the concentration used. Test fields were pretreated as follows: PT 0, field without any PT (control); PT 1, prick with lancet; PT 2, prick with test stamp; PT 3, scratch with lancet; PT 4, incision with standardized incision instrument (0.1-0.2 mm depth). Skin reactions were evaluated by transepidermal water loss (TEWL), skin erythema and skin hydration and as well by a visual score (VS) at 4, 24 and 72 h. RESULTS: Our data show an obvious distinction between PT 0-2 and PT 3-4 at all measurement methods. The average TEWL values with PT 3-4 were higher than those with PT 0-2, especially on the 4-h course. This distinction may derive from the shape and size of the skin impairment achieved by PT 3-4, leading to a mechanical barrier disruption. However, SLS may infiltrate directly into deeper skin layers supported by capillarity. Consequently, no or little penetration through the epidermis and interaction with its structures occurs, which is responsible for irritant skin reactions. The SLS dose in the upper skin layers is therefore lower at these PTs. The lower remaining dose of SLS also explains this distinction, especially for the VS. Additionally, there are presumed reactions in deeper layers of the epidermis and dermis at PT 3-4. CONCLUSIONS: In summary, all data suggest a different reaction pattern from the classical irritant response. Therefore, application without any PT seems to be best suited for irritancy skin testing, especially for visual assessment. PTs prior to irritant patch testing have been shown to be unjustifiable.     

Augmentation of skin response by exposure to a combination of allergens and irritants - a review

Clinical experimental studies on contact dermatitis (CD) often evaluate the effect of one allergen or one irritant at a time. In real life, the skin is often exposed to more allergens, more irritants or allergens and irritants in combination. This combined exposure may potentially influence irritant effects as well as allergenicity of the substances. Mechanisms for a changed response can be immunological effects or enhanced penetration. Knowledge about the influence on skin reaction of combined exposures may influence skin reactivity and is important for prevention of CD. For allergens, threshold values may be influenced by the presence of other allergens or irritants, and prevention of CD by regulation of threshold values may not be sufficient if this is not taken into account.     

Implementation of fatty acid carriers to skin irritation and the epidermal barrier

Acute perturbations are followed by barrier repair and enhanced lipid synthesis, as well as cellular fatty acid trafficking, yet irritation of the skin may be induced by repeat disturbance of barrier function. Recently, new insights in cellular fatty acid transport and metabolism have evolved with respect to skin irritation and barrier disturbances: (1) Employing sodium dodecyl sulfate, skin irritation is accompanied by the induction of an epidermal (E) cytosolic fatty acid binding protein (FABP) associated with enhanced barrier repair. Whether E-FABP contributes to the water barrier function in normal skin remains to be elucidated; (2) Cutaneous inflammation, as it occurs in irritant contact dermatitis, can be reduced by peroxisome proliferating activated receptor (PPAR) agonists, such as linoleic acid, with clinical effects comparable to that of glucocorticoids; (3) PPARalpha agonists accelerate barrier recovery and enhance lamellar body synthesis, neutral lipid synthesis, in particular that of ceramides and cholesterol; (4) PPARalpha agonists increase the minimal erythema dose in UVB-irradiated human skin. This review provides a brief overview of the current understanding of mammalian fatty acid (FA) metabolism with respect to epidermal barrier abrogation and repair, including new insights into cellular FA transport and metabolism.     

The influence of repeated exposure to surfactants on the human skin as determined by transepidermal water loss and visual scoring

The purpose of this study was to develop a new model for the induction of chronic irritant contact dermatitis, which would reflect well the conditions of daily practice. Various weak irritant agents were tested for irritating potency on the skin and the sensitivity of transepidermal water loss (TEWL) measurements in the detection of early skin changes was also studied. 10 widely used surfactants and 1 solubilizer were applied to the skin of the forearms of healthy volunteers in aqueous solutions of 12.5 millimoles/l for 45 min twice daily for 3 weeks. The effect on the skin was evaluated daily by means of TEWL measurements and by a visual scoring system. Each solution caused an increase in TEWL value over time due to the cumulative irritating action on the epidermal barrier. This increase in TEWL was different for the various solutions, resulting in different mean TEWL values on the last day of the experiment. Thus, it was possible to rank the agents according to irritating potency. This ranking order was the same in almost every individual and remained constant during the 3 weeks. In comparison with the visual scoring system, the TEWL measurements were more sensitive in the detection of early changes in the skin.     

Effects of skin occlusion in patch testing with sodium lauryl sulphate

BACKGROUND: When evaluating transepidermal water loss (TEWL) in patch testing, the occlusive effect of the patch must be considered as an important artificial impairment of the measurement. OBJECTIVES: To investigate the time course of effects of occlusion. METHODS: Epicutaneous patches with sodium lauryl sulphate (SLS) 0.25%, SLS 0.5%, water and an empty test chamber (control) were applied on the volar forearm for different time intervals (12, 24, 48 h). Test reactions were evaluated by measurement of TEWL immediately, every 15 min during the first hour, every 30 min during the following 3 h and 24 h after patch removal. RESULTS: After patch removal, TEWL values showed a steep increase. When compared with basal values, TEWL values after SLS patch testing remained increased for 24 h, whereas TEWL values on water patch sites were only significantly increased for up to 180 min, and on empty patch sites for only up to 120 min after patch removal. The prolonged increase in TEWL values in SLS patch testing seemed to be induced by barrier function damage caused by SLS itself, as shown in various earlier studies. After the initial increase, TEWL values showed a significant decrease for all patches from 0 to 120 min after patch removal. Patch testing with water gave a significant decrease in TEWL values up to 180 min, and for empty chambers (control) up to 150 min after removal of patches. These data suggest that the occlusive effect on TEWL in patch testing ends 3 h after the removal of test chambers. CONCLUSIONS: We recommend TEWL measurement in SLS patch testing after a period of at least 3 h after patch removal. For practical purposes a 24-h period after patch removal may be useful.     

Time course of occlusive effects on skin evaluated by measurement of transepidermal water loss (TEWL) Including patch tests with sodium lauryl sulphate and water

The time course for transepidermal water loss (TEWL) for a period of 3 h after removal of occlusive patch tests with sodium lauryl sulphate (SLS), water and empty chambers was studied in healthy volunteers. Patches were applied to the upper arm for 24 h, TEWL was measured immediately after removal of the patches, and every 30 min up to 3 h. For SLS and water patches, TEWL remained significantly increased for 3 h. as compared to normal adjacent skin, while for empty chamber patches. TEWL was only significantly increased for 30 min. A significant decrease from 0 to 30 min and from 30 to 60 min was observed for all patches, and for water patches, a significant decrease in TEWL was found from 60 to 180 min, while SLS patches remained constant. The prolonged increase in TEWL observed after SLS exposure is a well-known occurrence. The prolonged increase in TEWL after exposure to water is interpreted as transient damage to the water harrier of the skin.     

免疫磁性技术分离提纯酵母样真菌的研究

用包被有羊抗鼠ＩｇＧ的磁珠结合鼠抗白念单抗后，对白念珠菌，类星形念珠菌，类星形念珠菌，热带念珠菌，新生隐球菌，光滑念珠菌菌悬液及白念珠菌与新生隐球菌两菌混悬液进行了分离纯化研究。结果：免疫磁球和白念珠菌，类星形念珠菌结合尤为明显，与热带念珠菌少量结合而不和新生隐球菌，光滑念珠菌结合。     

Efficacy of stratum corneum lipid supplementation on human skin

Recent studies suggest that supplementing intercellular lipids of the stratum corneum in ageing populations or in people with dry skin can stimulate the functioning of the skin. This work lends support to the reinforcement capacity of two different stratum corneum lipid mixtures (synthetic stratum corneum lipid mixtures, SSCL, and internal wool lipid extracts, IWL) formulated as liposomes on healthy skin of two differently aged groups of individuals. Protection of healthy skin against detergent-induced dermatitis was evaluated. Transepidermal water loss and capacitance were used to evaluate the effect of these formulations in in vivo long-term studies. Increase in water-holding capacity is obtained only when the formulations applied are structured as liposomes. This is slightly more pronounced for aged skin. Subsequent SLS exposure reflected the protection of healthy human skin against detergent-induced dermatitis. Slightly better results were obtained with IWL containing a mixture of natural ceramides than with SSCL with only one ceramide present in the formulation. All these results support the beneficial effects of skin lipid supplementation given their resemblance to the lipids in the stratum corneum both in composition and in the structuring of the formulation.     

Barrier recovery and influence of irritant stimuli in skin treated with a moisturizing cream

Moisturizers are used daily by many people to alleviate symptoms of clinically and subjectively dry skin. Recent studies suggest that certain ingredients in creams may accelerate the recovery of a disrupted barrier and decrease the skin susceptibility to irritant stimuli. In the present single-blind study, a moisturizing cream was tested for its influence both on barrier recovery in surfuctant-damaged skin and on the susceptibility of normal skin to exposure to the irritant sodium lauryl sulphate (SLS). Parameters measured were transepidermal water loss (TEWL) and skin corneometer values, indicating degree of hydration. Treatment of surfactant-damaged skin with the test cream for 14 days promoted barrier recovery, as observed as a decrease in TEWL. Skin corneometer values also normalized more rapidly during the treatment. In normal skin, use or the test cream significantly reduced TFWL after 14 days of treatment, and irritant reactions to SLS were, significantly decreased. Skin corneometer values increased after only 1 application and remained elevated after 14 days. In conclusion, the accelerated rate of recovery of surfactant-damaged skin and the lower degree of SLS-induced irritation in normal skin treated with the test cream may be of clinical relevance in attempts to reduce contact dermatitis due to irritant stimuli.     

Effect of mineral oil and linoleic-acid-containing emulsions on the skin vapour loss of sodium-lauryl-sulphate-induced irritant skin reactions

This study evaluates the influence of mineral oil and linoleic-acid-containing emulsions on the skin vapour loss (SVL) of detergent-induced irritant skin reactions. During a period of 2 weeks, 2 x 45 min applications of a sodium lauryl sulphate solution of low molarity were performed on the forearm of 9 volunteers. In the same period, a standard amount of each emulsion was applied on the induced irritant skin reactions, 3 times each day. The effect of the emulsions on the barrier function of the skin was evaluated by means of SVL measurements. The emulsion based on mineral greases significantly reduced SVL values during both weeks, possibly because of an occlusive effect. The emulsion with 15% of linoleic acid significantly reduced SVL values during the 1st week but not during the 2nd week. The emulsion with 38% of linoleic acid did not reduce SVL values at all.     

The intra- and inter-individual variability and reliability of transepidermal water loss measurements

An analysis of variance was conducted to estimate the intra- and inter-individual variations in TEWL on the forearms, by sites (8 measurement sites) and by days (10 different days), in 30 non-exposed healthy individuals. The estimated intra- and inter-individual variations, by sites, were 15.5% and 84.5%, respectively, the sum of the 2 components always being 100%. With the exclusion of the 2 most distal sites near the wrist, which had significantly higher baseline TEWL values and fluctuations in TEWL, an improvement in the intra-individual variation was obtained. Thus, of the 6 sites, the estimated intra- and inter-individual variations were 8.4% and 91.6%, respectively. This finding supports the exclusion of these most distal sites for future investigations. The estimated intra- and inter-individual variations, by days, were 20.6% and 79.4%, respectively. The low site-to-site (8.4%) and day-to-day (20.6%) intra-individual variations, as compared to the large inter-individual variations of the same (91.6% and 79.4%), indicate that baseline TEWL is a stable personal characteristic. Thus, individual susceptible to irritant contact dermatitis (ICD), due to occupational exposure, may be reliably characterized by utilizing their baseline TEWL values, for "prediction" of risk in epidemiological field studies.     

Efficacy of 4 commercially available protective creams in the repetitive irritation test (RIT)

Protective creams (PCs) play their part in the prevention of occupational contact dermatitis, even though efficacy data are frequently lacking. 4 different commercially-available PCs were evaluated against a set of 4 standard irritants (10%, sodium lauryl sulfate (SLS) 1% sodium hydroxide (NaOH), 30% lactic acid (LA) and undiluted toluene (TOL) in the repetitive irritation test (RIT) in humans described by Frosch and Kurte. 20 subjects were tested on the paravertebral skin on the mid-back. Irritation was assessed by visual scoring, transepidermal water loss (TEWL) as an indicator of epidermal barrier function, and colorimetry as a parameter of inflammation. Very different protective effects of the PCs on irritation by chemical substances were detectable. All products were very effective against SLS irritation. No PC provided significant protection against toluene. 3 products showed a partially protective effect against all ionic irritants, while the 4ih showed less protection against SLS and NaOH, and even amplification of inflammation by TOL. Considering the range of PC effects from good protection 10 increased irritation, depending on the irritant, the need for careful selection of PCs for specific workplaces is stressed.     

面部糖皮质激素依赖性皮炎患者经皮水分丢失和皮肤含水量分析

目的 分析面部糖皮质激素依赖性皮炎患者的皮肤屏障功能。方法 将面部分为额部、鼻尖、下颌、双面颊、双侧口角的皮损区及左耳后无皮损区共8个点，分别测量95例面部糖皮质激素依赖性皮炎患者及25例健康对照者的经皮水分丢失（TEWL）和皮肤含水量。结果 与健康组相比，面部糖皮质激素依赖性皮炎组下颌、双侧口角、双面颊TEWL值均显著升高（t值分别为4.90，2.60，2.57，2.54，3.77，P < 0.01）；双侧口角、右面颊及额部的皮肤含水量均显著降低（t值分别为3.27，3.81，2.02，2.78，P < 0.05）。在8个测量点中，面部糖皮质激素依赖性皮炎组与健康组TEWL值均为下颌及双侧口角 > 双面颊及额部 > 耳后无皮损区；皮肤含水量降低均为下颌及双侧口角 > 双面颊及额部 > 耳后无皮损区。结论 面部糖皮质激素依赖性皮炎患者下颌、双侧口角、双面颊区域皮肤屏障功能受损，口周区域TEWL值较高，而面颊皮肤水分含量较少。     

Experimental irritant contact dermatitis due to cumulative epicutaneous exposure to sodium lauryl sulphate and toluene: single and concurrent application

In clinical practice, cutaneous exposure to a variety of irritants such as surfactants and solvents is frequent. Although the induction of irritant dermatitis by single irritants has been extensively studied in recent years, our knowledge of the effects of simultaneous application of different irritants is limited. Using non-invasive techniques for measurements of transepidermal water loss (TEWL) and skin colour reflectance, we quantified the irritant effects of single and concurrent application of 0.5% sodium lauryl sulphate (SLS) and undiluted toluene (TOL) in vivo. The irritants were applied twice daily for 30 min to the volar forearms of 20 volunteers. Repeated application of SLS and TOL induced an irritant reaction, as indicated by an increase in TEWL and skin redness. In contrast to SLS alone, the application of TOL alone induced only a moderate increase in TEWL, confirming previous results. Concurrent application of SLS/TOL and TOL/SLS induced significantly stronger reactions than those caused by twice daily application of each irritant on its own. Our results demonstrate that a mixed application of an anionic detergent and an organic solvent has an additive effect on skin irritation. It is suggested that pretreatment with SLS causes an increased susceptibility to TOL irritation and vice versa. Thus, the necessity for special precautions against skin absorption of TOL when handling detergents such as SLS is emphasized.     

Proper statistical analysis of transepidermal water loss (TEWL) measurements in bioengineering studies

In irritancy studies, measurement of transepidermal water loss (TEWL) is a widely used technique to assess barrier function. Using inappropriate statistical methods, however, leads to loss of information and misinterpretation of results. In this paper, we discuss some problems and pitfalls when using a suitable statistical technique for most designs in bioengineering studies, analysis of variance (ANOVA): multiple comparisons, choice of sample size and violation of statistical assumptions. For clarification of these points, a practical example will be given. Using the proposed adequate statistical methods correctly will, although accompanied by increased complexity, increase the efficiency of bioengineering studies.