Baseline transepidermal water loss in 3 different anatomical regions in healthy and eczematous subjects

Occlusive properties of monolayer patches: in vitro and in vivo evaluation

PURPOSE

Patches can cause a different grade of skin occlusion, depending on matrix composition and thickness, backing layer material. The aim of this work was to verify if in vitro water vapour permeability (WVP) values are predictive of transepidermal water loss (TEWL) and Fourier-transform infrared (FTIR) spectroscopy values measured in vivo after 24 h of methacrylic or acrylic monolayer patches application. The correlation between both in vivo methods has been evaluated.

METHODS

The WVP, TEWL and FTIR measurements were performed by using four patches made of a methacrylic or an acrylic polymeric system (250 and 500 microm thickness on a polyurethane backing layer). A fifth patch was made of the methacrylic matrix on a polvvinyl chloride backing layer. RESULTS. A good correlation was found between TEWL values and IR water/lipid absorbance ratios. The in vitro WVP values are in a good correlation with the results of both in vivo methods: TEWL = -().()WVP + 21.31 (R2 = 0.9312): FTIR water/lipid ratio = -0.01WVP + 27.15 (R2 = 0.9447).

CONCLUSIONS

The in vitro method proposed for measuring the WVP is predictive of the degree of occlusion resulting from the in vivo application of monolayer patches.

Skin barrier function in patients with completely healed atopic dermatitis

Although it has been well established that the dry skin often seen in patients with atopic dermatitis shows a deranged barrier function, there is no unanimity of opinion as to whether the barrier in normal-appearing skin of patients with the disease is deranged or not. Hence, it remains unclear whether individuals with atopic dermatitis constitution have an intrinsic derangement of skin barrier function or not. To settle this problem, in the present study we examined transepidermal water loss and stratum corneum water content in normal appearing skin of the upper back of 16 patients with completely healed atopic dermatitis who had been free from skin symptoms for 5 years or more, 30 patients with active atopic dermatitis, and 39 healthy subjects. The transepidermal water loss values and the stratum corneum water content values in normal-appearing skin of the completely healed patients were not different from the values in normal controls. These findings indicate that skin barrier function is not disturbed in patients with completely healed atopic dermatitis.

Baseline transepidermal water loss in patients with acute and healed irritant contact dermatitis

To examine the skin barrier function of patients with acute and healed irritant contact dermatitis (n = 80) baseline transepidermal water loss (TEWL) was quantitatively measured using an evaporimeter. Healthy subjects served as controls (n = 40). Test areas were the forearm and the thigh. A significant increase in TEWL was observed in the patients with acute and with healed irritant contact dermatitis (ICD) as compared to healthy volunteers (P < or = 0.01). TEWL values in both test areas were comparable and markedly correlated (P < or = 0.01) with each other in every group. Thus, it is possible that basal TEWL depends more on the intrinsic skin barrier function of the subjects rather than the 2 anatomical regions examined. TEWL at the forearm with acute ICD was significantly higher (P < or = 0.01) than that of the group with healed ICD, but not for TEWL at the thigh suggesting that ICD may aggravate the barrier function of the adjacent uninvolved skin. It is assumed, that increased basal TEWL in patients with ICD may reflect a constitutional deviation of epidermal barrier function. This event seems to be comparable with the well-known symptom of atopic individuals. Using a detailed atopic scoring system in such a study may clarify the question of whether a proportion of patients with hand ICD may indeed be atopic individuals.