Cutting oil dermatitis on guinea pig skin

The effect of repeated exposure of cutting oil on 8 guinea pigs' skin was evaluated by visual scoring for erythema and skin water vapour loss (SVL) measurement over a 6-week period. The visual scores (measuring severity of erythema) and SVL values were significantly higher on skin treated with cutting oils (positive control) compared to untreated skin (negative control) throughout the study period. The scores and SVL values returned to near-baseline values when cutting oil application was stopped. In addition, the effect of 2 "after-work" emollient creams on 8 guinea pigs' skin repeatedly treated with a cutting oil was assessed by similar methods. The visual scores and SVL values of guinea pig skin that was repeatedly treated with the cutting oil and moisturized with "after-work" emollient creams, were significantly higher than negative and positive control guinea pig skin. It appeared that the 2 "after-work" emollient creams do not alleviate the irritant effect of the cutting oil on guinea pig skin. They appeared to aggravate the irritant effect of the cutting oil.     

Cutting oil dermatitis on guinea pig skin

We assessed the effect of repeated application of cutting oil on 9 guinea pigs' skin by visual scoring and skin water vapour loss measurement. The visual scores (severity score) were significantly higher on skin treated with cutting oil (positive control) compared to untreated skin (negative control). The corresponding mean SVL values were also significantly higher. We also assessed the effect of 2 barrier creams on the 9 guinea pigs' skin treated with cutting oil. The visual scores on skin treated with either barrier cream were significantly higher than positive control skin. The corresponding mean SVL values on skin treated with either barrier cream were also higher (not statistically significant). It appeared that the 2 barrier creams did not confer protection against the irritant effect of the cutting oil. On the contrary, barrier creams appeared to exacerbate the irritant effect of cutting oil.     

Repair of acetone- and sodium lauryl sulphate-damaged human skin barrier function using topically applied emulsions containing barrier lipids

BACKGROUND: It is generally acknowledged that well-formulated moisturizing skin care products can restore disturbed barrier function that can be assessed by transepidermal water loss (TEWL) measurements. When ceramides and/or other barrier lipids are incorporated, it is, however, not always clearly demonstrated which ingredients of the formulation exert the beneficial effects. OBJECTIVES: In this study the effects of topically applied ceramide-containing mixtures on the barrier repair of sodium lauryl sulphate (SLS)- and acetone-induced skin damage have been studied in human volunteers. TEWL and stratum corneum hydration measurements were carried out. The emulsions applied contained either a mixture of two types of ceramides, CerIII and CerIIIB (emulsion 1) or a complete mixture of ceramides III, IIIB and VI together with phytosphingosine, cholesterol and the free fatty acid linoleic acid (emulsion 2). RESULTS: After SLS damage, it was observed that barrier recovery was significantly accelerated by topical application (14 days, 2 x/d) of emulsion 2 compared with the results obtained with emulsion 1. Corneometrical results were not relevant due to the occurrence of scaly fissured skin, failing to provide a good skin/probe contact. Although no effect on TEWL could be observed, the improvement of skin hydration after acetone treatment and a single application of the emulsions, was significantly more positive for emulsion 2 than for emulsion 1. CONCLUSIONS: The investigative methods used in this study show that ceramides combined with other skin lipids can improve barrier repair after damage.     

Efficacy of skin barrier creams (IV). The repetitive irritation test (RIT) with a set of 4 standard irritants

An improved human model for the quantification of skin barrier creams (BCs) is described. In contrast to the previously published procedure, the back, instead of the forearm, and a total of 4 irritants are used. Due to the larger area, 3 BC formulations can be simultaneously compared to the control field, which receives the irritant only, without BC-pretreatment. On 10 human volunteers, the irritants 10% sodium lauryl sulfate (SLS), 1% sodium hydroxide (NaOH), 30% lactic acid (LA) and undiluted toluene (TOL) were applied via large Finn Chambers for 30 min, 5 × during the 1st week and 4 × during the 2nd week. Taktosan Salbe (water-in-oil emulsion) and RAWI Speerschutzcreme (oil-in-water emulsion) were applied 30 min before contact with the irritants. In order to asses reproducibility and interindividual variation, the BC RAWI was tested in duplicate. Irritant cutaneous reactions were quantified by 4 parameters: erythema score, transepidermal water loss, blood flow volume and stratum corneum hydration by measuring capacitance. The results showed marked differences in efficacy. Taktosan significantly suppressed irritation by SLS, NaOH and LA, which was apparent in nearly all parameters. RAWI caused significant inhibition of SLS irritation, and a positive trend against NaOH and LA was observed. Both BCs failed against TOL. The results of duplicate testing with RAWI showed good reproducibility. The dogma that oil-in-water emulsions are primarily effective against lipophilic irritants, and water-in-oil emulsions against hydrophilic irritants, needs to be re-evaluated on the basis of our findings. This model seems to have potential for further studies on BCs and might elucidate the complex interaction of BCs with irritants.     

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.     

Ceramide 1 and ceramide 3 act synergistically on skin hydration and the transepidermal water loss of sodium lauryl sulfate-irritated skin

Background  Stratum corneum intercellular lipids, such as ceramides, play an important role in the regulation of skin water barrier homeostasis and water-holding capacity.
Aim  To evaluate the potential water retention capacity of control emulsion and three oil-in-water (o/w) emulsions containing ceramide 1, ceramide 3, or both.
Methods  Fifteen healthy Asian women (age, 20–30 years) with healthy skin, pretreated with sodium lauryl sulfate (SLS), applied the tested emulsions twice daily over a period of 28 days. Skin hydration and transepidermal water loss (TEWL) values were measured on the indicated days with a Corneometer®825 and a TEWAMETER TM210, respectively.
Results  The maximum increase in skin humidity was reached after 4 weeks, with values of 21.9 ± 1.8% and 8.9 ± 0.9% for emulsion C and control emulsion, respectively. The maximum decrease in TEWL was also reached after 4 weeks, with values of 36.7 ± 4.7% and 5.1 ± 0.8% for the same emulsions.
Conclusions  It can be concluded that all the tested ceramide-containing emulsions improved skin barrier function when compared with untreated skin. There was some indication that ceramides 1 and 3 contained in emulsion C might exert a beneficial synergistic effect on skin biochemical properties, such as skin hydration and TEWL, and play a key role in the protection mechanism against SLS irritation.     

两种维生素E乳剂保湿性的比较

目的了解维生素E乳喷雾剂的保湿效果及患者的依从性,与对照乳液比较,评价其优劣。方法共观察40例受试者,采用自身对照试验,分别在基线、2周后、4周后检测靶部位皮肤的角质层含水量、经表皮失水率、pH值,受试者主观评价。结果全部受试者均完成了试验,未发生不良反应。2组之间靶部位的角质层含水量、经表皮失水率、pH值在0,2,4周时差异均无统计学意义（P〉0．05）。2组靶部位的角质层含水量在2周及4周后均较基线时显著升高,差异有统计学意义（P〈0．01）;而表皮失水率和pH值较基线时无明显变化,差异无统计学意义（P〉0．05）。多数受试者（67．5％）认为喷雾剂优于乳膏剂。结论维生素E乳喷雾剂保湿效果好,与对照乳液的保湿效果相当,优点是清爽、无香味。     

The effect of grenz rays on irritant skin reactions in man

To investigate the effect of grenz rays on irritant contact reactions, eleven healthy volunteers were studied. They were given 3 Gy of grenz rays, once a week for 3 weeks, to a defined area of the back. Twenty-four hours after the last treatment, serial dilution sodium lauryl sulphate patch tests were applied both on the grenz ray treated area and on the untreated control skin. Biopsy specimens were taken from the irritant reactions both from the grenz ray treated area and from the control area and different cell populations in dermis and epidermis were identified by monoclonal antibodies (Leu 2, 3, 4, 7, Leu M1, B1, OKT6). In the grenz ray treated epidermis there was a pronounced reduction of OKT6-positive cells but the composition of the dermal cellular infiltrate did not differ between control and grenz ray treated skin. The assessment of the patch test reactions did reveal a tendency towards weaker reactions in the grenz ray pre-treated skin but this difference was not statistically significant. It is concluded that grenz rays do not have a marked effect on the elicitation of irritant reactions.     

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.     

Efficacy of skin barrier creams

2 barrier creams (BC) were evaluated against the anionic detergent sodium lauryl sulphate (SLS) using a new human test model. In the repetitive irritation test (RIT) on human skin, the irritant SLS is applied to the ventral forearm of Healthy volunteers daily for 2 weeks. 1%, 5%, and 10% SLS is exposed to the skin for 30 min. using a glass cup 2.5 cm in diameter. The BC is applied 30 min before the irritant. Cutaneous irritation is assessed on a score for erythema (0 to 5+), and quantified by various biophysical techniques: transepidermal water loss (TEWL) by evaporimetry, skin blood flow volume (BFV) by laser-Doppler velocimetry, and -skill colour bi colorimetry (La^* value). 10 subjects were tested with SLS on one forearm without pretreatment (control) and with Taktosan Salbe as BC on the other forearm. A 2nd panel of 10 subjects was tested in the same way with SLS and Marly skin as BC. Taktosan Salbe was extremely effective in reducing the irritation by SLS: there were significant differences regarding all lest parameters for 10% SLS in the 2nd week. The most differentiating parameter was TEWL, revealing statistical differences as early as the 1st week for 10%. SLS and Taktosan Salbe, while the least differentiating sensitivity was found for La^*. In contrast, there was no significant suppression of irritancy in any parameter with Marly skin, either in the 1st week or in the 2nd week with any concentration of SLS. The results show the differentiating potential of the model developed. Results obtained with the previously described animal model are confirmed- Noninvasive biophysical techniques, particularly TEWL measurements, might be extremely valuable in identifying new active ingredients of BC.     

Efficacy of skin barrier creams

An animal model for the evaluation of skin protective creams against chemical irritants is described. The irritants were applied daily for 2 weeks to shaved back skin of young guinea pigs: sodium tauryl sulphate (5% aq.: 30 min), sodium hydroxide (0,5% aq.; 2 min). and toluene (20'i. eth.; 2 mint. "The harrier cream was applied 2 h prior to and immediately after exposure to the irritant. Control animals were treated with the irritant only. The irritant reaction was scored on a 4–point scale for erythema and quantified with regard to transepidennal water loss (TEWL) by evaporime-try and skin blood flow volume (BFV) by laser Doppler velocimetry. A total of 90 guinea pigs, consisting of" individual panels of 5 to 10 animals, was tested. While one barrier cream (Slokoderm) significantly suppressed the irritation due 10 sodium lauryl sulphate and toluene, the other (Contra-Alkalh failed to do so and even aggravated the response, which was particularly evident with sodium hydroxide. This model may be useful in developing more effective barrier creams.     

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.     

Effect of an antioxidant (quercetin) on sodium-lauryl-sulfate-induced skin irritation

Quercetin is a bioflavonoid with antioxidant and anti-inflammatory activity. The purpose of this study was to examine the effect of quercetin on acute skin irritation, with special interest in the skin barrier function recovery. Acute irritant contact dermatitis was induced in 15 patients by 24-h occlusion of 2% sodium lauryl sulfate (SLS) (day (D) 1). The influence of application on SLS-irritated skin of topical quercetin for 5 consecutive Ds, compared to vehicle and controls, was studied. Parameters measured were transepidermal water loss (TEWL) and erythema index. Final measurements were taken on D 7 after a 1-D rest period. TEWL and the erythema index continued to rise 2 D after application of SLS and 1 D after treatment with quercetin, vehicle or controls. Both TEWL and erythema values at D 7 did not return to values before the SLS barrier disruption at all the test sites. Therefore, quercetin topically applied after induction of irritant contact dermatitis does not appear to increase the recovery of barrier function and erythema caused by SLS.     

Immediate irritant reactions to benzoic acid are enhanced in washed skin areas

Factors affecting immediate irritant skin reactions are poorly understood. Our purpose was to study the effect of washing on reactions to benzoic acid, a well-known immediate-type irritant. 12 test subjects washed their left upper arms with a diluted dishwashing liquid 2× daily for 6 days. Benzoic acid in a dilution series was tested on both upper arms on days 0, 3 and 6. The reactions were graded visually, and the blood flow, skin color, transepidermal water loss and electrical capacitance of the test sites were measured. On days 3 and 6, the benzoic acid reactions were stronger on the washed arm than on the control arm. This was clinically visible and was associated with changes in blood flow and skin color measurements. Washing itself did not ususally cause visible erythema, but transepidermal water loss increased and electrical capacitance decreased. Low concentration of irritant substances, such as benzoic acid, may cause clinically relevant reactions in repeatedly washed skin. This should be taken into consideration in assessing product safety in the cosmetic, medical and household chemical industries, and when tests for chemical skin irritancy are designed and the results of such tests interpreted.     

Biophysical characterization of skin damage and recovery after exposure to different surfactants

The majority of adverse skin reactions to personal-care products are presumed to be caused by irritant substances, like surfactants. In this study, different aspects of the irritant reaction after a single exposure to 8 surfactants were characterized during 2 weeks. Solutions of 2% sodium lauryl sulfate, 5% sodium C12-15 pareth sulfate, 5% sodium cocoyl isethionate, 10% disodium laureth sulfosuccinate, 10% sodium cocoamphoacetate, 10% cocamide DEA, 10% cocamidopropyl betaine and 10% lauryl glucoside, respectively, were applied to the forearm of 12 volunteers. Clinical assessment, an evaporimeter, a laser Doppler flowmeter and a corneometer were used for evaluation. The surfactants induced different degrees of irritation. Erythema, transepidermal water loss and skin blood flow exhibited a similar time course, which seemed to be inversely related to the delayed scaling and reduced skin capacitance. The mechanism of the damaging effect of the surfactants seems to be similar, although some minor differences were noted.     

Clinically normal atopic skin vs. non-atopic skin as seen through electrical impedance

BACKGROUND/AIMS: In an earlier study, we have shown that the electrical impedance (IMP) is dependent on the lipid content of the stratum corneum as studied by lipid extraction. Therefore, we now employ the IMP technique to compare the properties of clinically normal atopic skin with that of non-atopic skin. We looked at the same time at concomitant alterations in transepidermal water loss (TEWL) and skin moisture results. METHODS: Twenty-two healthy participants and 26 patients with atopic dermatitis were recruited. One test site on each volar forearm was used in the test procedure, of cyclohexane swabbing, skin stripping, and lipid extraction using a mixture of hexane:isopropanol. Responses were evaluated by measuring TEWL, skin moisture using electrical capacitance, and finally IMP spectroscopy in the frequency range 1 kHz to 1 MHz before the start of the study, after each step of the test procedure, and also during a 2 weeks recovery period. RESULTS: Only the IMP results showed significant changes between baseline values of clinically normal atopic skin and healthy skin. Furthermore, IMP and TEWL showed significantly larger reactivity for the atopic group after the skin stripping procedure, and IMP after lipid extraction as well. CONCLUSION: Our results show that IMP is a useful method for detection of changes in the lipid content of the stratum corneum by discriminating healthy looking atopic skin from healthy control skin, and to detect changes in reactivity between the two groups.     

Efficacy of topical corticosteroids on irritant skin reactions

Topical corticosteroids are frequently used in the treatment of irritant contact dermatitis (ICD). The efficacy of this treatment has, however, not been thoroughly established, and experimental studies on the topic have provided conflicting results. The aim of the present study was to evaluate the effect of potent topical corticosteroids on experimentally-induced irritant skin reactions in a double-blind, vehicle-controlled study. 16 healthy volunteers had sodium lauryl sulfate patch tests symmetrically applied to the upper arms. After removal of patch tests, a potent topical cortico-steroid (betamethasone-17-valerate) was applied to the irritant skin reaction on one arm, while the corresponding vehicle was applied to the irritant skin reaction on the opposite arm 2 × daily for 7 days. Reactions were evaluated by measurement of transepidermal water loss (TEWL) and erythema. After 7 days, statistically significant lower values of TEWL and erythema were found in corticosteroid-treated, compared to the vehicle-treated, skin reactions. The results indicate that topical corticosteroids improve healing of ICD.     

Investigation of functions of essential fatty acids in the skin

Essential fatty acid-deficient rats develop scaly skin that has impaired barrier properties and lowered concentrations of linoleic and arachidonic acids in phospholipids. Topical linoleic acid restores impaired barrier function to normal (within 5 days) and increases the amount of linoleic acid in skin lecithin, but has no effect on the low levels of arachidonic acid in this phospholipid, or on skin scaliness, during this time. Topical butyl PGE₁ or butyl PGE₂ for 1 week have no effect on scaliness, impaired barrier function or lipids. Also, the effect of linoleic acid on barrier function is seen even when prostaglandin synthesis has been inhibited by repeated administration of indomethacin. Intraperitoneal linoleic acid also repairs barrier function but has no simultaneous effect on scaliness; and arachidonic acid, similarly administered, rapidly heals skin scaliness, without simultaneously repairing barrier function. Hypophysectomized rats, which grossly resemble essential fatty acid-deficient rats (their skin is scaly), exhibit virtually normal skin fatty acids, and skin permeability is normal, but such animals do not synthesize prostaglandins. These date indicat that of the 2 major essential fatty acids of rat skin, linoleic and arachidonic acids, athe former is found esterified to phospholipids of epidermal membrancs and is also important in the maintenance of the cutanecous barrier to water loss, whereas the latter, although also found in phospholipids, plays no part in barrier function. rather, it is important as a precursor of prostaglandins, which are thought to be involved in the regulation of normal cell division and differantiation of the epidermis, and, consequently, the control of skin scaliness. Hypophysectomized rats and essential fatty acid-deficient rats are similar as neither can synthesize adequate prostagladins, the former probably because the multi-enzyme complex of prostaglandin synthetase in faulty, the latter due ot ethe absence of essential fatty acid precursors.     

Intra-individual variation of irritant threshold and relationship to transepidermal water loss measurement of skin irritation

Irritant susceptibility studies have used either visual assessment or transepidermal water loss (TEWL) to determine subject response. We have developed a visual assessment method which determines subject irritant threshold. We examined the relationship between sodium lauryl sulfate (SLS) irritant threshold and TEWL measurements from normal skin and SLS patch tests. 19 subjects were recruited. The irritant threshold of each subject was measured and TEWL measurements made from the applied SLS patch tests. Individuals with a lower irritant threshold (easily irritated skin) had elevated TEWL levels compared to those with higher thresholds. The irritant threshold test had a low intraindividual variation. This study showed that the 2 methods grouped patients in a similar manner. The variation seen may reflect the different outcomes measured: irritant threshold visually assesses the skin inflammatory response while TEWL measures skin barrier modification.     

Long-term repetitive sodium lauryl sulfate-induced irritation of the skin: an in vivo study

Skin may adapt to topical irritants through accommodation. This study focuses on long-term exposure to irritants and attempts to demonstrate accommodation. Sodium lauryl sulfate (SLS) induced irritant contact dermatitis at 3 concentrations (0.025% to 0.075%). Distilled water, acetone and an empty chamber served as controls. Experimental compounds were applied to forearms of 7 healthy volunteers for 24 hr before replacing by a fresh chamber for 6 non-consecutive weeks over 103 days. Possible accommodation was quantified by visual scoring (erythema and dryness) and by bioengineering parameters: transepidermal water loss (TEWL), capacitance, chromametry and laser Doppler flowmetry (LDF). Significant erythema, dryness, elevated TEWL, skin colour reflectance and LDF values occurred during the exposure periods. Upon repeat exposure, an immediate and augmented response in erythema, TEWL, skin colour reflectance and LDF developed. However, irritant skin changes were not sustained. Irritation parameters return to baseline after cessation of exposure. There was no evidence of sustained irritation or accommodation after the last exposure. Study findings do not document sustained accommodation or adaptive hyposensitivity after long-term repetitive irritant exposure under these test conditions. Alternative models should be developed to prove or disprove the accommodation hypothesis.