Patterns of aluminum hydroxychloride deposition onto the skin.

BACKGROUND: Aluminum hydroxychloride (AlCl(3) ) is an antiperspirant. AIM: To revisit the AlCl(3) deposition in vivo and in vitro on glass slides and stratum corneum (SC) harvested by cyanoacrylate skin surface strippings (CSSS). METHODS: Transepidermal water loss (TEWL) was assessed following application of 5% AlCl(3) on the forearms. The AlCl(3) -coated skin, glass slides and CSSS were observed using two ultraviolet light-emitting CCD cameras in order to record changes in specular reflectance related to AlCl(3) deposition. In addition, the corneoxenometry bioassay was performed in order to predict AlCl(3) irritation. RESULTS: AlCl(3) deposited on glass slides looked as linear threads and rings of similar sizes. AlCl(3) deposits on skin were almost restricted inside the microrelief lines and as annular deposits at their crossings where acrosyringia are opening. After daily AlCl(3) applications, deposits extended on the CSSS plateaus. At rest in absence of sweating, TEWL was decreased following AlCl(3) applications. During physical exercise, the TEWL increase was limited on the AlCl(3) areas. CSSS appeared unreactive to AlCl(3) at the corneoxenometry bioassay. CONCLUSION: The similar aspect of AlCl(3) deposits on human SC and on glass slides suggested a physical property of AlCl(3) . Repetitive applications of AlCl(3) increased both the deposit area and the barrier function.

Facing up to the imperceptible perspiration. Modulatory influences by diabetic neuropathy, physical exercise and antiperspirant.

BACKGROUND: Sweating is variably altered by physical exercise, diabetic neuropathy and antiperspirants. METHODS: Skin temperature, skin surface water loss (SSWL), the Corneometer(®) average capacitance (CMAC) and skin capacitance mapping (SCM) were measured before and after moderate physical exercise in 20 healthy subjects. The effect of 5% aluminium chloride hexahydrate (ACH) in a water solution was similarly tested. The same assessments were performed in 20 diabetic patients at rest. RESULTS: Diabetic neuropathy appeared at rest as an increased (compensatory) SCM on the forearms without obvious modification on the hypohidrotic legs. On ACH sites after exercise, SCM revealed both a lowered number of active sweat glands and a lighter stratum corneum (SC) (dryness). In addition, CMAC and SSWL were decreased on ACH sites at rest and at completion of exercise. CONCLUSION: In diabetic neuropathy, the compensatory hyperhidrosis is more easily disclosed than the hypohidrosis. ACH affects both sweat excretion and the SC hydration.

The skin landscape following nonoptical capacitance imaging.

Skin capacitance is an electrical property measurable at the level of the stratum corneum. Values are related to the moisture content of the tissue. Using the silicon image sensor technology, it has recently become possible to measure capacitance at 50 microm intervals on the skin surface. The resulting nonoptical picture corresponds to skin capacitance imaging. This novel tool for dermatologists highlights with precision the hollow skin surface patterns, including dermatoglyphics, the patterns of the shallow skin lines, and wrinkles. The topographic heterogeneity in skin surface hydration is made visible. In addition, the sweat gland and follicular openings are disclosed. Skin disorders induced by surfactants or presenting as hyperkeratotic areas, including some neoplasms, may show typical aspects. It is concluded that skin capacitance imaging brings added value to the clinical assessment performed by dermatologists.

Epidermal field carcinogenesis in bald-headed: An attempt at finetuning early non-invasive detection.

Skin weathering and photoaging of the balding scalp have not attracted much investigative attention so far. However, the concept of field cancerization, in particular actinic field carcinogenesis, is likely applicable to this part of the body. The aim of the study was to finetune the epidermal actinic changes present on hairlessness scalp. The ultraviolet light-enhanced visualization (ULEV) method was used to assess a series of 50 healthy men older than 50 years with documented baldness for over 15 years. They were scrutenized looking for altered epidermal structures corresponding to photoaging-associated changes. Attention was focused on the faint mosaic melanoderma (FMM) and atypical scaliness. Observations were made on the scalp and forehead. FMM was recognized in each case. It presented either as a single manifestation of photoaging or it was associated with an unusual pattern of discrete rimmed scaliness. In this latter case histology and morphometry disclosed keratinocyte dysplasia. A similar scaly pattern was not seen on the forehead. Subtle skin surface changes were disclosed on long-standing sunexposed balding scalps. The scaly aspect was distinct from dandruff, seborrheic dermatitis or any other common inflammatory scalp dermatosis. The presently described changes had not previously been described during early balding. It is suggested that the presently described condition may be associated with or indicative for actinic field carcinogenesis and incipient keratinocyte dysplasia.

Effects of various concentrations of glycolic acid at the corneoxenometry and collaxenometry bioassays.

BACKGROUND: Glycolic acid is an alpha-hydroxy acid used as a chemical peeling for more than a quarter century. The primary tissue target is the stratum corneum. OBJECTIVE: This study aims to assess the effects of various concentrations of glycolic acid on the stratum corneum and collagen fibers using two selected bioassays. METHODS: Corneoxenometry was performed to test the effects on human stratum corneum. Collaxenometry was similarly designed to quantify the effect on sheets of collagen fibers. Different glycolic acid concentrations ranging from 5% to 70% in alcohol were tested, respectively, for 3- and 10-min exposure times. RESULTS: Both bioassays showed consistent reactivities with a dose-effect relationship when using a 3-min exposure time. By contrast, the tests appeared unreliable or uninformative for the 10-min exposure time. CONCLUSION: Corneoxenometry and collaxenometry appear useful for in vitro testing peeling agents during short exposure times.

Skin protection creams in medical settings: successful or evil?

BACKGROUND: Chronic exposure to mild irritants including cleansing and antiseptic products used for hand hygiene generates insults to the skin. To avoid unpleasant reactions, skin protection creams are commonly employed, but some fail to afford protection against a variety of xenobiotics. In this study, two skin protection creams were assayed comparatively looking for a protective effect if any against a liquid soap and an alcohol-based gel designed for hand hygiene in medical settings. METHODS: Corneosurfametry and corneoxenometry are two in vitro bioessays which were selected for their good reproducibility, sensitivity and ease of use. A Kruskal-Wallis ANOVA test followed by the Dunn test was realized to compare series of data obtained. RESULTS: Significant differences in efficacy were obtained between the two assayed skin protection creams. One of the two tested creams showed a real protective effect against mild irritants, but the other tested cream presented an irritant potential in its application with mild irritants. CONCLUSION: The differences observed for the two tested skin protection creams were probably due to their galenic composition and their possible interactions with the offending products. As a result, the present in vitro bioassays showed contrasted effects of the creams corresponding to either a protective or an irritant effect on human stratum corneum.

Dew point effect of cooled hydrogel pads on human stratum corneum biosurface.

BACKGROUND: Cooled hydrogel pads are used to prevent overheating effects of laser therapy. They do not induce cold injuries to the skin, but their more subtle physiological effects have not been thoroughly studied. PURPOSE: To describe the changes in transepidermal water loss and electrometric properties of the skin surface following application of cooled hydrogel pads. Measurements were performed on normal forearm skin of 27 healthy volunteers and on freshly excised skin from abdominoplasty. METHODS: LaserAid hydrogel pads cooled to 4 degrees C were placed for 15 min on the forearm skin. Measurements of transepidermal water loss (TEWL) and electrometric properties (Corneometer, Nova DPM 900) were performed before application and after removal of the cooled pads. RESULTS: A consistent increase in corneometer units, dermal phase meter (DPM) values and TEWL were recorded at removal of the cooled hydrogel pads. Both the in vivo and in vitro assessments brought similar information. DISCUSSION: The similar changes disclosed in vitro and in vivo suggest that a common physical process is operating in these conditions. The observed phenomenon is opposite to the predicted events given by the Arrhenius law probably because of the combination of cooling and occlusion by the pads. A dew point effect (air temperature at which relative humidity is maximal) is likely involved in the moisture content of the stratum corneum. Thus, the biological impact of using cooling hydrogel pads during laser therapy is different from the effect of a cryogenic spray cooling procedure. The better preservation of the water balance in the stratum corneum by the cooled hydrogel pads could have a beneficial esthetic effect on laser treated areas.

Regional variability in stratum corneum reactivity to antiseptic formulations.

Skin does not react in an identical way to the action of chemicals over all anatomic sites. Accordingly, distinct regional differences have been described in relation to irritancy. The present study assesses the regional variations of stratum corneum (SC) reactivity to 3 proprietary antiseptic solutions (povidone iodine (PVP-I), 70 mg/ml and 100 mg/ml, and chlorhexidine digluconate 50 mg/ml) using the corneoxenometry (CXM) bioassay. SC was harvested from the volar forearm, the forehead and the back in 30 young adults. Each SC sample was covered by one of the neat test product or deionized water for 2 hr at 20 degrees C. The intrinsic staining property of each antiseptic on SC was assessed by reflectance colorimetry. For the CXM bioassay, samples were then stained by a toluidine blue-basic fuschin solution in order to show protein denaturation induced by the test products. The colorimetric index of mildness (CIM = L*- Chroma C*) was measured by colorimetry. Data show that PVP-I 100 mg/ml was the least reactive antiseptic to the SC. It was significantly milder than the 2 other antiseptics.

Skin capacitance imaging of acne lesions.

BACKGROUND: Little information is available about specific functional characteristics of skin in acneic patients. OBJECTIVE: To determine a capacitance mapping of lesional skin in acne in order to predict drug affinity according to the hydrophilic-lipophilic characteristics. METHOD: Skin capacitance imaging based on silicon image sensor technology was used with the SkinChip device. RESULTS: The non-optical images obtained by this means clearly identified low capacitance comedones contrasting with a perifollicular rim of high capacitance in inflammatory papules. This method also showed sweating and the follicular pores distributed in a pinpoint pattern. CONCLUSION: The objective mapping of skin surface capacitance showed large differences between acne lesions and the surrounding skin. The low capacitance of comedones contrasted with the high capacitance of the perifollicular area in inflammatory papules. These electrometric characteristics reflecting the corneocyte hydration may influence drug affinity to acne lesions.

Skin capacitance imaging, a new technique for investigating the skin surface.

Thanks to the recently introduced silicone image sensor technology, skin capacitance imaging has now been made possible. The dedicated device is called SkinChip. This method is easy to handle and provides information about the skin microrelief, the level of stratum corneum hydration and the sweat gland activity. The apparatus sees and measures these parameters with a 50 microm resolution. A series of conditions have been explored using skin capacitance imaging. This review summarizes relevant findings about regional variability on the body, changes occurring with ageing, effects of a hydrating formulation, reactivity kinetics of corneocytes to surfactants, acne and skin pores characteristics, as well as hyperkeratotic dermatoses and tumours.

Highlighting the rim of the perifollicular epidermal unit.

The perifollicular and interfollicular areas of normal skin may look similar. However, some physiological and pathological processes may specifically involve a thin perifollicular rim. This review illustrates some of the methods available for highlighting the rim of the perifollicular epidermal unit. Non invasive methods rely on dermoscopy, ultraviolet light enhanced visualization (ULEV), skin capacitance imaging and cyanoacrylate skin surface strippings (CSSS). Conventional histology and immunohistochemistry may also show specific perifollicular features without, however, revealing the aspects highlighted by the specific non invasive methods. The clinically relevant modifications consist of pigmentary and hyperkeratotic perifollicular changes.

Skin capacitance imaging and corneosurfametry. A comparative assessment of the impact of surfactants on stratum corneum.

Silicon image sensor (SIS) technology was recently introduced as an innovative tool (SkinChip, L'Oréal) providing sensitive imaging of the skin capacitance. This method can detect discrete focal variations in skin surface hydration, and thus early discrete manifestations of skin irritation induced by surfactants. In the present in vivo study, 2 neat and diluted shampoos, and 5% and 10% sodium laurylsulfate solutions were tested on human skin. Each surfactant solution was gently rubbed on the skin using wet hair wicks mimicking the casual use of a shampoo on the scalp. Clinical and SIS evaluations were carried out. In addition, the same products were tested using the ex vivo corneosurfametry bioassay performed on human stratum corneum (SC) harvested by cyanoacrylate skin surface strippings. The colourimetric index of mildness (CIM) was measured on these samples. The product reactivity with the SC was recognized by darker skin capacitance images, and by both lowered SkinChip-generated values and lowered CIM values. The extent in changes varied according to the nature of the test products and their concentrations. The SkinChip image changes likely corresponded to the acute surfactant-induced water swelling of the corneocytes. Skin capacitance imaging and corneosurfametry allow to disclose discrete surfactant-induced alterations of corneocytes.

The key role of corneocytes in pityrosporoses.

Pityrosporoses encompass various Malassezia-driven conditions. Dandruff and seborrheic dermatitis are members of this family of disorders. Their precise pathomechanisms have not been completely elucidated so far. This review focuses on the role of corneocytes in these disorders. Malassezia yeasts are not evenly distributed at the surface of the stratum corneum. Rather, they are clumped on some corneocytes while other corneocytes in their vicinity are almost free of these microorganisms. The corneocytes heavily coated by yeasts suggest a cell-related defect in the mechanisms controlling the skin biocene including the natural antimicrobial peptides and nitric oxide. Most environmental factors influencing pityrosporoses indeed affect the natural human defenses against certain microorganisms. We frame as a hypothesis that the primary defect in some Malassezia-driven disorders resides in the corneocytes and their precursor keratinocytes.