The effect of washing on the thickness of the stratum corneum in normal and atopic individuals

The report describes a method for the assay of five enzymatic activities involved in establishing the stratum corneum permeability barrier: β-glucocerebrosidase, acid phosphatase, phospholipase A₂ (PLA₂) and two serine proteases: chymotrypsin and its activator in the stratum corneum, trypsin. The specific activities of these different enzymes have been determined along with their pH profiles and sensivities to specific inhibitors. It can be noted that only two presented a pH optimum similar to the pH of the stratum corneum. This could suggest that their activities are regulated by local variations in pH. The method was applied to a pathological situation, that of a non-eczematous dry atopic dermatitis. Atopic skin had significantly reduced trypsin activity, increased acid phosphatase and no change in the activities of three other studied enzymes. Understanding these activities can provide a tool for the characterization of skin pathologies and for the development of a certain number of applications in cosmetology and therapeutics.

Section: Discussionmentioning

confidence: 99%

Characterisation and Assay of Five Enzymatic Activities in the Stratum Corneum Using Tape-Strippings

Redoulès

Tarroux

Assalit

et al. 1999

“…This can lead to peeling of corneocytes ('keratolysis'). Such an effect could be demonstrated by the assay of a thinning of the horny layer [23,24].…”

Section: Effects Of Aqueous Solutions Of Emulsifying Agents On the Homentioning

confidence: 99%

How Do Dermatological Vehicles Influence the Horny Layer?

Gloor

2004

Emulsifying agents in aqueous solution lead to dehydration of the horny layer of the epidermis and damage to the barrier. This is only partly true if emulsifying agents are constituents of emulsions. Water-in-oil (W/O) emulsions cause an improvement in the hydration of the horny layer and barrier function. In the case of an additional effect of wash solutions, a partial or complete abolition of the drying out and barrier-damaging effect of the wash solution results. Oil-in-water (O/W) emulsions without glycerol have no effect on the moisture of the horny layer or indeed increase it, but they lead to considerable damage to the barrier and irritation. In wash tests, they do not induce any protective effect. With micro-emulsions this is still more the case and, moreover, they can also lead to exsiccation. As a result of the addition of glycerol, the barrier-damaging effect can be abolished. Also in stress tests with wash solutions, the damage to the horny layer is reduced by glycerol-containing O/W emulsions. Whereas the penetration-promoting effect of O/W emulsions without glycerol is best, only W/O emulsions or glycerol-containing O/W emulsions are suitable for atopic dermatitis. A hydrating effect on the stratum corneum was also found in a propylene glycol ointment.

“…Studying both healthy volunteers and patients with atopic dermatitis, White et al [3] found reductions in stratum corneum cell layers and intercellular lipids in patients with atopic dermatitis. In both populations, washing with soap (no details given) twice daily for 7 days produced reductions in stratum corneum cell layers and intercellular lipids.…”

Section: Discussionmentioning

confidence: 99%

“…The prototypes of indirect keratolytic agents are retinoids, which interfere with the keratinization pro- Gloor/Haus/Keipert cess. Direct keratolytic activity has also been postulated for surfactants [2][3][4]. Microemulsions (MEs) with a relatively high surfactant content may therefore also have keratolytic activity.…”

Section: Introductionmentioning

confidence: 99%

Keratolytic Activity of Microemulsions

Gloor

Haus

Keipert

2003

Objective: To compare the keratolytic activities of a drug-free hydrophilic microemulsion (ME) and a drug-free lipophilic ME with water, and with regard to the hydrophilic ME also with a 5% salicylic acid gel on the sole of the foot. Methods: Twenty healthy volunteers had their plantar forefoot, midfoot, and rearfoot stratum corneum blackened with silver nitrate and a photographic developer, and a chromameter was used to determine the extent of removal of this black dye by a* value and L value measurement at 24 and 48 h. Results: Both drug-free MEs produced significantly greater increases in a* value and L value than water, and the hydrophilic ME was also more effective than 5% salicylic acid gel. Conclusion: The irritating effect of MEs is rather negligible on the sole of the foot because of the thick plantar stratum corneum. Both MEs therefore appear suitable for the elimination or prevention of plantar desquamative and hyperkeratotic skin changes.