Effect of occlusive dressings on the stratum corneum water holding capacity.

Occlusion of the skin is used in clinical dermatology to promote wound healing and to increase the transcutaneous penetration of topically applied drugs. These effects are related to the degree of occlusion exerted and depend on the physicochemical nature of the dressing. We have evaluated the effects of four different materials on the skin barrier and the stratum corneum water holding capacity (WHC) using the Plastic Occlusion Stress Test (POST). The following materials were compared: hydrocolloid dressing, polyurethane film, polyethylene film, and a plastic chamber. These devices were applied on the volar forearm for 24 hours in 10 healthy volunteers (mean age 32 +/- 4 years). Upon their removal, the stratum corneum WHC, measured as skin surface water loss (SSWL), was recorded continuously for 25 minutes using an Evaporimeter. SSWL decay curves showed significant differences between the occlusive materials (analysis of variance, p less than 0.01). Higher SSWL values were recorded in sites occluded with the plastic chamber, whereas the polyurethane film resulted in poor occlusive capacity. Hydrocolloid dressing and polyethylene gave similar responses with higher WHC values compared to polyurethane (p less than 0.05). The relevance of these findings to clinical dermatology in terms of wound healing and drug absorption is discussed.

Blood transfusions in the therapy of a case of prolidase deficiency.

A case is reported of a 15-year-old boy with prolidase deficiency and marked urinary excretion of the iminodipeptide gly-pro. Prolidase activity of erythrocytes against substrate glycyl-proline was deficient, but after blood transfusions this was increased to 15.7% of donor activity and declined to 12% and 3.4% of normal activity after 8 and 45 days, respectively. Urinary iminodipeptide levels following transfusion remained unaltered.

Ranking of surfactant skin irritancy in vivo in man using the plastic occlusion stress test (POST).

Irritant effects and disturbance of water-holding capacity induced by surfactants were investigated using the plastic occlusion stress test (POST) technique. 4 surfactants (sodium lauryl sulphate (SLS), sorbitan monolaurate, cocoamidopropyl betaine and benzalkonium chloride) and an amphoteric/nonionic (A/N) mix were investigated. 1 x daily for 3 days, test surfactants were applied to marked sites (open) on the volar forearm. After 24 h occlusion with a plastic chamber on the 4th day, skin surface water loss (SSWL) (g/m2h) was recorded continuously for 25 min with an evaporimeter. The differences between the surfactants were statistically significant (Friedman's test p less than 0.01). SLS and the A/N mix revealed significant differences compared to the other compounds (p less than 0.05), both in decay constants and in values recorded at the beginning and at the end of the decay curve. The study suggests a mechanism for the high irritant potential of sodium lauryl sulphate compared to other surfactants: sorbitan monolaurate and benzalkonium chloride seem to influence (at the concentrations tested) to a lesser extent the water-holding capacity of the stratum corneum. The clinical and biological relevance of these observations requires long-term clinical correlations with final product use tests.

In vivo hydration and water-retention capacity of stratum corneum in clinically uninvolved skin in atopic and psoriatic patients.

Hydration and the water-retention capacity of stratum corneum have been investigated in uninvolved psoriatic and atopic skin and compared with that of healthy controls. Thirty-three subjects of either sex and matched for age entered the study. The subjects were free from all signs of skin disease and skin dryness. Hydration was evaluated by means of transepidermal water loss and skin capacitance measurements. Water-retention capacity was investigated using the plastic occlusion stress test. Atopic skin differed significantly from uninvolved psoriatic and control skin which had a reduced water content and an increased transepidermal water loss. Furthermore, the skin surface water loss profile representing the stratum corneum water-retention capacity was significantly lower in normal atopic skin. The data suggest that clinically normal skin may be functionally abnormal, resulting in a defective barrier that could lead to higher risk of irritant or contact dermatitis.

Effects of a topical preparation on some hair growth parameters, evaluated utilizing a morphometric computerized analysis.

Synopsis The action of a topical preparation on some hair growth parameters has been evaluated. The morphometric computerized analysis applied to photographic images of a predetermined area (with shots after cutting and after 96 h) enabled an estimation of the percentage of elements in active growth phase compared to the total number, the length of all elements and that of the sole elements in active growth phase after 96 h and the growth with respect to the base values; statistically significant differences are observed before and after 60 days treatment. L'évaluation des effets d'un topique sur quelques paramètres de la croissance des cheveux à travers une analyse morphométrique informatisée.