Véronique Goffin

Surfactant-induced dermatitis: Comparison of corneosurfametry with predictive testing on human and reconstructed skin

BACKGROUND Surfactants elicit alterations in the stratum corneum. Predictive tests that avoid animal experimentation are needed. OBJECTIVE This study compares three methods of rating and predicting shampoo-induced irritation. METHODS Corneosurfametry entails collection of stratum corneum followed by brief contact with diluted surfactants and measurement of variations in staining of samples. RESULTS Corneosurfametry appears to correlate well with in vivo testing in volunteers with sensitive skin. However, corneosurfametry presents less interindividual variability than in vivo testing and allows better discrimination among mild products. Morphologic information about surfactant-induced loosening of corneocytes may be increased by testing surfactants on human skin equivalent. Results are similar to those provided by specimens used for corneosurfametry. CONCLUSION The corneosurfametric prediction of surfactant irritancy correlates with in vivo testing and with in vitro evaluation on human skin equivalent.

Corneosurfametry: A Predictive Assessment of the Interaction of Personal-Care Cleansing Products with Human Stratum corneum

OBJECTIVE Corneosurfametry is introduced as a noninvasive quantitative test rating the interaction between surfactants and human stratum corneum. It may be used as a predictive irritancy test. BACKGROUND Surfactants present in personal-care products elicit multiple effects on the stratum corneum. With upcoming regulations avoiding animal experiments and ethical considerations for human testing, there is a need for new in vitro methods evaluating irritancy. DESIGN Corneosurfametry entails collection of cyanoacrylate skin surface strippings and short contact time with surfactants followed by staining samples with toluidine blue and basic fuchsin dyes. Measurements are made by reading the color of samples using reflectance colorimetry. RESULTS The intensity of color increases with irritancy potential of the surfactant. Results are reproducible, and great differences are noted among a series of diluted shampoos, shower gels and facial cleansing gels. CONCLUSION Corneosurfametry is proposed as a rapid in vitro method allowing a predictive grading of surfactants related to irritancy.

A Multicenter Randomized Trial of Ketoconazole 2% and Zinc Pyrithione 1% Shampoos in Severe Dandruff and Seborrheic Dermatitis

Ketoconazole (KET) and zinc pyrithione (ZPT) are compounds active against the Malassezia spp. yeasts, which are believed to play a major role in dandruff and seborrheic dermatitis. We compared the efficacy and safety of KET 2% and ZPT 1% in shampoo formulations for the alleviation of severe dandruff and seborrheic dermatitis. This open randomized, parallel-group trial began with a 2-week run-in phase during which subjects applied a neutral nonantidandruff shampoo. It was followed by a 4-week randomized treatment phase and a subsequent 4-week follow-up phase without treatment. Shampooing during the treatment period was carried out twice weekly for the KET group and at least twice weekly for the ZPT group in accordance with the label instructions. A total of 343 subjects were recruited to enter the trial. Of the 331 eligible volunteers, 171 were randomized to KET 2% and 160 to ZPT 1%. Clinical assessments were performed. Beneficial effects were evidenced for both medicated shampoos, but the effect was significantly better for KET 2%, which achieved a 73% improvement in the total dandruff severity score compared with 67% for ZPT 1% at week 4 (p < 0.02). The recurrence rate of the disease was also significantly lower following KET 2% treatment than following ZPT 1% treatment. As a consequence, the overall clearing of the skin condition at the end of treatment and follow-up phase was in favor of the KET 2% formulation (p = 0.004). Side effects were minimal. It is concluded that after a 4-week treatment, KET 2% shampoo was significantly superior to ZPT 1% shampoo in the treatment of subjects with severe dandruff or seborrheic dermatitis of the scalp. It is our assumption that this difference is noticeable for the patient and as a consequence relevant. Both formulations were well tolerated.

Sensitive skin and stratunm corneum reactivity to household cleaning products

Products intended for individuals with sensitive skin are being increasingly developed by formulators of household cleaning products. However, there is currently no consensus about the definition and recognition of the biological basis of sensitive skin. We sought to determine the relation between the nature of environmental threat perceived as aggressive by panelists, and the stratum corneum reactivity lo household cleaning products as measured by the corneosurfametry lest. Results indicate substantial differences in irritancy potential between proprietary products. Corneosurfametry data show significant differences in stratum corneum reactivity between, on file one hand, individuals with cither non‐sensitive skin or skin sensitize to climate‐fabrics, and, on the other hand, individuals with detergent‐sensitive skin. It is concluded that sensitive skin is not one single condition. Sound information in rating detergent sensitive skin may be gained by corneosurfametry.

Comparison of in vitro predictive tests for irritation induced by anionic surfactants

Skin compatibility of anionic surfactants may often but not always he predicted by vitro tests. For instance, the correlation between in vivo and in vitro data is classically hampered in the presence of magnesium. This ion is known to interfere with in vitro skin irritation predictive test based on protein denaturation. This study was conducted to compare a recently introduced assay, corneosurfametry, with other in vitro tests including the pH‐rise of bovine serum albumin, collagen swelling, and zein solubilization tests. Corneosurfametry entails collection of eynoacrylate skin surface strippings and short contact time with surfactants, followed by staining samples with toluidine blue and basic fuchsin dyes. Measurements are made by reflectance colorimetry. Data show that irritation potentials predicted by corneosurfametry agree with those obtained by established in vivo and in vitro irritation tests. Moreover, corneosurfametry data are not artificially lowered by addition of magnesium in surfactant solutions. In conclusion, corneosurfametry should be viewed as one of the realistic predictive tests for surfactant irritancy.

Mechanical Properties of Skin in Ehlers‐Danlos Syndrome, Types I, II, and III

Abstract: Mechanical properties of skin were evaluated in vivo in 17 children suffering from Ehlers‐Danlos syndrome (EDS) types I, II, and III. These were compared with normal values from 63 healthy children. Non‐invasive measurements were performed under suction of 500 mbar using a Cutometer equipped with a 4‐mm probe. Prominent increases in skin extensibility and elasticity were the most distinctive and diagnostic features of all three EDS types. Differences in the average values of biome‐chanical variables were present among the three types. Patients with EDS‐I were the most affected, whereas those with EDS‐III had virtually normal skin. However, interindividual differences in the severity of rheo‐logical alterations were found within each type, illustrating a continuum in the variation of mechanical properties of EDS skin rather than yielding step differences among the types.

Digital Image Analysis of Microcomedones

OBJECTIVE Developing a technique for quantifying the number and size of follicular casts and microcomedones. BACKGROUND There is no human testing that is validated up to now to predict comedogenesis and comedolysis following topical applications of drugs or cosmetics. DESIGN Evaluations are performed by digital image analysis of cyanoacrylate follicular biopsies. The effects of two topical products are compared. RESULTS Microcomedogenesis was disclosed after a 2-month period of application of a cosmetic product aimed at treating acne. Microcomedolysis occurred following usage of a topical preparation containing benzoyl peroxide 5% and miconazole nitrate 2%. CONCLUSION Digital image analysis of skin surface biopsies is a sensitive method documenting microcomedo formation and dissolution.

Lymecycline and minocycline in inflammatory acne: A randomized, double-blind intent-to-treat study on clinical and in vivo antibacterial efficacy

Background: Some antibiotics represent a mainstay in acne treatment. However, studies comparing their efficacies are rare. Aim: To evaluate the clinical and in vivo antibacterial effect of lymecycline and minocycline at different dosages. Method: Eighty-six patients with moderate to severe acne were enrolled in a randomized, double-blind, intent-to-treat study comparing in three parallel groups the effect of (1) lymecycline 300 mg daily for 12 weeks, (2) minocycline 50 mg daily for 12 weeks and (3) minocycline 100 mg daily for 4 weeks followed by 50 mg daily for 8 weeks. Evaluations were made at the screening visit and at five on-treatment visits. They consisted of clinical counts of acne lesions and evaluations of bacterial viability using dual flow cytometry performed on microorganisms collected from sebaceous infundibula by cyanoacrylate strippings. Results: Patients receiving minocycline 100/50 mg had the best clinical outcome, particularly in the reduction of the number of papules. By the end of the trial, the microbial response to minocycline 100/ 50 mg was also superior to either of the other two treatments. There were less live and more dead bacteria. Conclusion: In this trial, minocycline 100/50 mg was superior for the treatment of inflammatory acne when compared to lymecycline 300 mg and minocycline 50 mg.

Beneficial Effects of Softened Fabrics on Atopic Skin

There is general concern about the possible cutaneous adverse effects of wearing garments treated with household laundry products, particularly on atopic skin. Our objective was to compare softened and non- softened fabrics in a forearm wet and dry test, under conditions simulating real-life conditions. Twenty atopic volunteers entered a single-blind 12-day (3 sessions per day) forearm wetting and drying test. Cotton fabrics were machine washed and liquid fabric conditioner was added or not to the final rinse. To simulate conditions of skin damage, a dilute solution of sodium lauryl sulphate was applied under occlusion to the forearm of each volunteer before the start of the study. Skin effects were evaluated by visual grading (redness, dryness and smoothness), squamometry and in vivo instrumental measurements (capacitance, transepidermal water loss and colorimetry). Rubbing of atopic skin with fabrics generally resulted in discrete to moderate alterations of the structure of the stratum corneum. Both for control and pre-irritated skin, all measured parameters indicated that softened fabric was less aggressive to the skin than unsoftened fabric. In the case of pre-irritated skin, the recovery of the skin was significantly faster when rubbed with softened than with unsoftened fabrics. In conclusion, softened fabrics help mitigate the skin condition in atopic patients.

Regional differences in stratum corneum reactivity to surfactants. Quantitative assessment using the corneosurfametry bioassay.

The skin does not react similarly to the presence of xenobiotics over all anatomic sites. Distinct regional differences have been described for irritancy and percutaneous absorption. The present study assesses the regional variation of stratum corneum reactivity to surfactants using the corneosurfametry bioassay. Stratum corneum was harvested from 6 body sites in 20 young adults. Corneosurfametry was performed using water, 1% SLS and a 5% soap solution. Data show that the best variable to assess regional variability in irritancy is the overall difference in corneosurfametry (ODC), comparing the effect of a given surfactant with water. The dorsal hand and volar forearm were the least reactive, the neck, forehead, back and dorsal foot the most reactive, sites. It is concluded that the corneosurfametry bioassay, through the ODC variable, is a practically non invasive tool for the evaluation of regional variation in irritancy at the level of the stratum corneum.