Alpha hydroxyacids (AHAs) are used to enhance stratum corneum desquamation and improve skin appearance. The purpose of this study was to evaluate whether some AHAs improve skin barrier function and prevent skin irritation. Eleven healthy subjects (aged 28 +/- 6 years, mean +/- SD) entered the study. Six test sites of 8 x 5 cm (four different AHAs, vehicle only (VE) and untreated control (UNT) were selected and randomly rotated on the volar arm and forearm. The four different AHAs at 8% concentration in base cream were glycolic acid (GA), lactic acid, tartaric acid (TA) and gluconolactone (GLU). The products were applied twice a day for 4 weeks (2 mg/cm2). At week 4, a 5% sodium lauryl sulphate (SLS) challenge patch test was performed under occlusion for 6 h (HillTop chamber, 18 mm wide) on each site. Barrier function and skin irritation were evaluated by means of evaporimetry (Servomed EP-1) and chromametry (a* value, Minolta CR200) weekly, and at 0, 24 and 48 h after SLS patch removal. No significant differences in transepidermal water loss (TEWL) and erythema were observed between the four AHAs at week 4. After SLS challenge, GLU- and TA-treated sites resulted in significantly lower TEWL compared with VE, UNT (P < 0.01) and GA (P < 0.05) both at 24 and 48 h. Similarly, a* values were significantly reduced after irritation in GLU- and TA-treated sites. This study shows that AHAs can modulate stratum corneum barrier function and prevent skin irritation; the effect is not equal for all AHAs, being more marked for the molecules characterized by antioxidant properties.

Surfactant-induced irritant reactions may be elicited by several endogenous and exogenous factors. Among these, surfactant concentration, and duration and frequency of exposure play important rôles. The study focuses on the influence of water temperature in determining damage of the skin barrier. 10 subjects of both sexes entered the study. 4 areas (4 x 4 cm2) were randomly selected on the volar forearm and were treated with a daily open application of 5% sodium lauryl sulphate for 4 days. The solutions were at 3 temperatures: 4 degrees, 20 degrees and 40 degrees C. One site served as untreated control. On the 5th day, skin irritation was evaluated using transepidermal water loss (TEWL) measurements, erythema (a* value), skin reflectance (L* value), hydration (capacitance) and desquamation (stripping). The results show a significant effect of the solution's temperature in determining skin irritation (P < 0.001). Skin damage was higher in sites treated with warmer temperatures and a highly significant correlation (P < 0.001) between irritation and temperature was found. In conclusion, the study shows that water temperature during washing has an important effect on the onset of irritant contact dermatitis.

An increase of sebum excretion rate (SER) is frequently observed in patients suffering from Parkinson's disease (PD). Some authors attribute it to the hyperactivity of the parasympathetic system, while others consider the possible action of androgens or of MSH-hormone. The aim of our study was to verify and quantify SER in 70 parkinsonian patients and compare it with SER in 60 normal subjects. We found higher values of SER in male subjects, both in normal and in parkinsonian patients. The highest rate of excretion was observed in parkinsonian males, in agreement with the possible main role of androgens or testosterone in sebum excretion, while the phenomenon did not appear to be related to abnormalities of the autonomic nervous system. The association of PD and sex hormones might therefore be crucial for the developing of seborrhea.