Assessment of the efficacy of a new formulation for plantar wart mummification: new experimental design and human papillomavirus identification.

Cutaneous warts are caused by infection of the epidermis with human papillomavirus (HPV). Cryotherapy using liquid nitrogen is one of the most common local treatments. In this study, we used a novel ex vivo approach to compare the efficacy of a new product with conventional liquid-nitrogen cryotherapy by studying epidermal histology and assessing the presence of HPV types 1 and 2 DNA in plantar warts. The studied formulation, which acts by tissues mummification, is a combination of nitric acid, organic acids and metallic salts. We found that, similar to liquid nitrogen, the studied product induced alterations in the wart structure. In addition, unlike liquid nitrogen, this product also reduced the amount of HPV DNA. The results suggest that there is a poor correlation between the histological response and the antiviral efficacy of standard wart treatment.

Assessment of the water content of the stratum corneum using a sorption-desorption test.

BACKGROUND/AIM: Various instruments based on electrical properties of the skin are currently used to assess the stratum corneum (SC) hydration state or water holding capacity. However, no direct relation with the quantity of water measured is provided. The objective of the present study was to calibrate the Corneometer, a device displaying electrical-capacitance-related values (which reflect the skin hydration state), and the amount and behaviour of the water taken up by the outer part of the SC during a sorption-desorption test. METHODS: The experiment was performed on the ventral forearms of 20 healthy volunteers after a rest in an environmentally controlled room. Corneometer and transepidermal water loss (TEWL) values were measured at intervals over the desorption process. The areas under the TEWL-versus-time curve provided the absolute amounts of residual sorbed water. RESULTS: The decrease kinetics of both signals after subtraction of prehydration values were very similar and bi-exponential, both showing a rapid, then a slower phase. The absolute amount of water taken up by the SC (hygroscopicity) and the two desorption rates were obtained. The Corneometer values were mono-exponentially related to the amount of water remaining within the SC. This allowed the in vivo calibration of the Corneometer in terms of absolute amount of water over the desorption range. CONCLUSION: The method may be used to calibrate in vivo other electrical devices aimed at assessing SC hydration during a sorption-desorption test. It may also provide new ways to measure SC water uptake and water holding capacity following application of products.

Simple equilibrium dialysis-high-performance liquid chromatographic method for the in vitro assessment of 5-methoxypsoralen bound to human albumin.

Increasingly used in therapeutics, 5-methoxypsoralen (5-MOP), a linear furocoumarin, associated with UVA irradiation (PUVA), is now an established treatment for skin diseases such as vitiligo, mycosis funcoides and particularly psoriasis. Successful PUVA therapy depends on a sufficiently high peak 5-MOP plasma concentration coinciding with the UVA irradiation. However, as with most drugs, only the free plasma fraction is able to enter the target cells and has a pharmacological effect. In this work, the binding of 5-MOP to human albumin was studied in vitro, using a dialysis chamber. Bound and free 5-MOP fractions were quantified by a modification of Stolk's high-performance liquid chromatographic method. Dialysis was performed at 37 degrees C and pH 7.4 for 2 h, against a 4% albumin solution in phosphate buffer. The 5-MOP concentrations used were from 5 x 10(-5) to 5 x 10(-2) g/l in 1 x 10(-1) g/l steps. The 5-MOP bound strongly to human albumin in an unsaturable way. The mean 5-MOP binding to albumin was 95.3%. These results are in accordance with those published by Artuc et al. and not with those of Veronese et al., who found a lower saturable fixation (91%). These two research groups used tritiated 5-MOP. The technique used in this work is simple and inexpensive. It can be employed easily in vivo, e.g., for the assessment of 5-MOP free fractions in different therapeutic conditions.