The tetracyclines in dermatology.

Tetracycline is one of the most widely used antibiotics. It may share some properties with conventional immunosuppressive drugs and act as an anti-inflammatory agent in the treatment of inflammatory disease. This article reviews cutaneous diseases that have been treated with tetracyclines and their antiinflammatory and immunosuppressive properties.     

Barrier function of the skin in a repetitive irritation model and influence of 2 different treatments*

Background/aims: The aim of this study was to develop and characterize an experimental model of cumulative irritant contact dermatitis using the repetitive application over 2 weeks of 2 different irritative stimuli, sodium lauryl sulphate (SLS) in low concentration and toluene. Further, it was intended to look at the effect of 2 different treatments which could influence the regeneration of the skin barrier, as already investigated in preliminary short-term experiments. Methods: Occlusive short-time daily application of the irritants (SLS 30 min; toluene 10 min) was performed. After removal of the occlusive patch, the irritated areas were treated with 2 different preparations, Lotio Alba Aquosa and vaseline (white petroleum jelly). Bioengineering techniques were used to precisely measure the skin condition. Results: A mild irritation was obtained under these experimental conditions. The bioengineering measurements allowed us to differentiate both irritants through their different influences on trans-epidermal water loss and skin hydration. Treatment with vaseline did not significantly influence the course of the irritation, but Lotio Alba Aquosa clearly potentiated it, whereby different effects were noticed for both irritative stimuli. Conclusions: The use of bioengineering techniques in this model of mild cumulative irritation allowed us to differentiate the action of both irritants, showing that they act through different mechanisms. The results of the treatments pointed out the need to treat an irritation with the right product for the right time period.     

Stratum corneum dynamic function measurements after moisturizer or irritant application

Two simple tests were conducted which allowed the quantification of parameters that characterize the stratum corneum (SC) dynamic functions in vivo under physiological conditions after moisturizer applications for 1 h and after irritation with different concentrations of sodium lauryl sulphate (SLS; 0.5–4%) applied under occlusion for 15 min or 24 h. Both tests, the sorption-desorption test (SDT) and the moisture accumulation test (MAT), were performed with a Nova Dermal Phase Meter 9003. The following parameters were quantified: prehydration state (SDT, MAT), hygroscopicity, water-holding capacity (SDT), water accumulation velocity and water accumulation (MAT). These procedures allowed the demonstration of the water-holding effect of urea contained in moisturizers. Differences between the long and the short application time of SLS were characterized by differences in SC dynamic functions while the hydration state was not changed. An effect on transepidermal water loss (TEWL) was noted only after the long application time, although the MAT clearly showed dynamic parameters to be changed after 15 min of treatment. These tests were simple in practice and allowed the demonstration of functional modifications of the SC while other parameters remained unchanged. They gave insight into possible action mechanisms of urea and SLS in the SC.     

Néphrite tubulo-interstitielle et maladie de Crohn,néphrotoxicité ou atteinte extradigestive de la maladie de Crohn ? À propos d’un cas

Extraintestinal manifestations in inflammatory bowel disease involve most frequently the joints, the skin, the eyes, the liver and the biliary tract. Renal involvement is rare, and manifested as nephrolithiasis, tubulointerstitial nephritis, glomerulonephritis and amyloidosis. In patients with inflammatory bowel disease, renal disease is most frequently due to treatment nephrotoxicity and rarely as a guenine extraintestinal manifestation of inflammatory bowel disease. We are reporting a case of tubulointerstitial nephritis as an extraintestinal manifestation of Crohn's disease and we are explaining the diagnostic difficulty to distinguish this from drug-induced nephrotoxicity.     

Transepidermal water loss related to volar forearm sites in humans.

The aim of this study was to demonstrate differences in human skin transepidermal water loss (TEWL) in vivo related to site on volar forearm. Fourteen healthy volunteers entered the study and seven sites were tested. After randomization of both forearm and measure order, TEWL measurements were performed using the Servo Med Evaporimeter. TEWL values next to the wrist were found statistically greater than on the other sites. Hence wrist region should preferably be excluded from TEWL measurements on forearm.     

A new micronized 5-methoxypsoralen preparation. Higher bioavailability and lower UVA dose requirement.

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.     

Skin Penetration and Sun Protection Factor of Ultra-Violet Filters from Two Vehicles

Purpose. In order to improve our knowledge on the efficacy and safety of sunscreen products, we measured the skin penetration profiles of ultra-violet (UV) filters in vitro and in vivo, and the corresponding sun protection factors (SPF) from two vehicles (an O/W emulsion-gel and petroleum jelly). Methods. The UV filters tested were oxybenzone (5%, A), 2-ethylhexyl 4-methoxycinnamate (7.5%, B), and 2-ethylhexylsalicylate (3%, C). Two mg/cm² were applied for 2 min to 6 h. In vitro penetration measurements were performed with static diffusion cells. In vivo, horny layer concentrations were measured after stripping and the SPF evaluated as recommended by the COLIPA-guidelines. Results. Significant differences between vehicles were noticed in vitro as well as in vivo. In vitro, the emulsion-gel generated higher epidermal concentrations than petroleum jelly. Values at 6 h, expressed as percent of the applied dose for A, B, and C were 4, 9, and 7% for the emulsion-gel and 2, 1, and 2% for petroleum jelly. An opposite trend was noticed, mainly for A, in the deeper skin layers with concentrations of 2% in the dermis and 5% in the receptor fluid for petroleum jelly and 0.6% and 1% for the emulsion-gel respectively. In vivo, for each UV filter, maximal stratum corneum levels (15 strips) were obtained at 0.5 h with percentages of the applied doses of 50% for the emulsion-gel and 15% for petroleum jelly. SPFs, measured 0.5 h after application amounted to 14 for the emulsion-gel and 5 for petroleum jelly, and decreased in both cases by a factor 2.2 after removal of non penetrated product. Conclusions. These preliminary results demonstrated that UV filters penetration and retention as well as expected SPF could be optimized by a suitable vehicle.     

Intestinal permeability in patients with psoriasis

A possible relationship between intestinal structure and function in the pathogenesis of psoriasis has recently brought about considerable interest. The purpose of this study was to evaluate the intestinal permeability in psoriatic patients by comparing it with healthy controls. 15 psoriatic patients and 15 healthy volunteers entered the study. Intestinal permeability was evaluated using the 51Cr-labeled EDTA absorption test. The 24-h urine excretion of 51Cr-EDTA from psoriatic patients was 2.46 +/- 0.81%. These results differed significantly from controls (1.95 +/- 0.36%; P less than 0.05). The difference in intestinal permeability between psoriatic patients and controls could be due to alterations in the small intestinal epithelium of psoriatics.