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Reactive oxygen species play an important role in inflammatory skin diseases such as psoriasis. Reactive oxygen species synthesis is catalysed by iron and some species are scavenged by ascorbic acid. The aim of this work was to assess iron and ascorbic acid in uninvolved and involved psoriatic dermis and to compare the corresponding concentrations in the dermis of healthy subjects. Microdialysis associated with atomic absorption spectrometry and gas chromatography-mass spectrometry was used to assess iron and ascorbic acid, respectively. Seven psoriatic patients and five healthy volunteers were studied. Iron concentrations in the involved (57.1 +/- 19.3 microg/l) and uninvolved (49.7 +/- 27.1 microgl/l) psoriatic dermis were higher than the corresponding value determined in the dermis of healthy subjects (21.8 +/- 2.4 microg/l) (p<0.05). Ascorbic acid in involved (47.3 +/- 8.2 microg/ml) and uninvolved (42.0 +/- 14.0 microg/ml) psoriatic dermis was statistically lower than that found in healthy dermis (176.8 +/- 29.0 microg/ml) (p<0.05). These results demonstrate that psoriatic patients exhibit high iron and low ascorbic acid concentrations in the dermis, but there were no significant differences between involved and uninvolved skin.

A new tablet of micronized 5-methoxypsoralen (5-MOP) and a commonly used tablet in therapy (Psoraderm 5) were compared in 12 healthy subjects. Each subject ingested 1.2 mg/kg body weight of each formulation on different days. Bioavailability and phototoxicity of 5-MOP were compared. The results showed that serum and suction blister concentrations were significantly higher and occurred earlier after the oral intake of the micronized preparation. A series of graduated UVA doses were administered, one dose each time the concentration serum peaked, in order to determine the minimum phototoxic dose for each formulation. The micronized preparation induced greater photosensitivity than the unmicronized one. The micronized 5-MOP tablet may thus allow lower doses of UVA to achieve therapeutic results in photochemotherapy and a shortened waiting period following ingestion of drug.

Diurnal variations in drug pharmacokinetics are a well known phenomenon. Chronopharmacology studies now appear to be attracting increasing interest with a view to establishing an optimum therapeutic prescription. In order to determine possible chronobiological variations of 5-methoxypsoralen (5-MOP) pharmacokinetic, 5-MOP blood concentrations were quantified in 8 healthy subjects after drug ingestion at different times during the day. Stolk's High Performance Liquid Chromatography technique was used to assess the 5-MOP serum concentrations. Each subject underwent three pharmacokinetic studies after oral ingestion of 5-MOP (1.2 mg/kg), in conjunction with a standardized low-lipid meal. The first pharmacokinetic study was started in the morning, the second in the afternoon and the third in the evening. Drug intake was at intervals of 2 days, to avoid drug accumulation. The results showed that the evening intake of the drug induced a higher 5-MOP maximum concentration and a higher 'area under curve' than morning or afternoon ingestion. This study suggests an optimized PUVA therapy, when performed in the evening.

The skin relief influences the exterior aspect of the skin which is very sensitive to aging. It could also be related to the mechanical properties and structure of both dermis and stratum corneum. Consequently, quantitative measurement of the skin surface roughness would seem most useful, as it would permit a quantification of skin aging, an in vivo analysis of mechanical forces acting on the skin structure, and the detection of abnormalities otherwise not visible. The method described comprises three steps: (1) making a silicone rubber negative replica, (2) making an Araldite positive cast, (3) roughness measurement of the cast with a device commonly used in engineering, which provides quantitative parameters: Ra, Rp, Rt, Rmax and others. The reliability of each of these steps was checked, and also the absolute need to locate precisely the site of sampling and to know the angle of the scanning direction with the main axis of the limb or the body. The method seems useful for studying aging, either normal or affected by UV rays and other physiopathological events influencing the skin surface.