Reversal effects of topical retinoic acid on the skin of kidney transplant recipients under systemic corticotherapy.

The systemic long-term corticosteroid treatment administered to kidney graft recipients (KGR) within the framework of the required immunosuppressive therapy induces an atrophy of the skin, from the sixth month onwards. We studied the effect of topical all-trans retinoic acid (0.05%; Galderma Labs.) applied to the forearms of 27 KGR (14 men, 13 women) over a 6-month period. Twenty-four subjects completed the trial. The following results were obtained in the treated forearm versus the untreated forearm (excipient alone): clinically, an increase in skin thickness; by noninvasive techniques, an increase in skin thickness, skin elasticity, skin conductance, and TEWL, and a reduction in the size of the corneocytes. No change in stratum corneum lipid content was observed. A sex-related difference was noted in the response to treatment under our experimental conditions, the female patients responding better. A punch biopsy (4 mm) was performed on both forearms of four patients after the 6-month period. Histologic and ultrastructural examination revealed epidermal and dermal changes evoking increased cellular metabolism in the retinoic acid-treated forearms.

Miniature pig as an animal model to study photoaging.

Seven miniature pigs were irradiated thrice weekly over a 14 months period with suberythematogenic doses of UVB and UVA. Another seven were not exposed, to record innate aging changes. Chronic irradiation induced the following changes: 1. Increased scaling, with thickening of the stratum corneum and decreased reactivity to acetic acid. 2. Increased minimum erythema dose, corresponding to decreased transmission of UV-radiation through isolated epidermis. 3. Increased elastic fibers, accompanied by strong deposition of glycosaminoglycans in the upper dermis. 4. Increased laxity with greater extensibility to a deforming torque. 5. Increased density of vessels. 6. More disorderly arrangement of collagen bundles with minor alterations in collagen biochemistry. These changes mimic those in photoaged human skin but are milder in degree, attributable to the low total dosage of ultraviolet radiation.

In vivo evaluation of photoprotection against chronic ultraviolet-A irradiation by a new sunscreen Mexoryl SX.

In a previous study on the hairless mouse it was shown that sub-erythemal doses of pure UV-A enhanced the numerous changes normally observed during chronological aging. A new sunscreen (a bis-benzylidene campho sulfonic acid derivative) has been synthesized in our research laboratory (lambda max: 345 nm, epsilon: 47,000). Its photoprotective properties against UV-A induced damages were assessed in our mouse model. Three month old albino hairless mice were exposed for 1 y to suberythemal doses (35 J/cm2) of UV-A obtained from a xenon source filtered through a WG 345 filter. One group of animals was exposed untreated, the other received a formulation containing 5% of the sunscreen prior to irradiation. At the end of the study the cutaneous properties of protected mice were compared to those of unprotected animals and to 3 and 15 month old unirradiated controls. We found that the visible changes induced by UV-A irradiation were mainly sagging and wrinkling. Histological and electron microscopic alterations consisted of hyperkeratosis, increased density of elastic fibers with alteration of fiber orientation and increased glycosaminoglycan deposits. Biochemical changes consisted of decreases in total collagen and collagen hydroxylation and increases in both collagen III/I + III ratio and fibronectin biosynthesis. All these changes were reduced or abolished by the sunscreen.

The lipometre: an easy tool for rapid quantitation of skin surface lipids (SSL) in man.

The purpose of this study is to present a rapid, simple, and accurate method for quantitation of SSL in man. The technique which is derived from the works by Schaefer and Kuhn-Bussius, employs a series of clearn ground glass plates, and an apparatus, the Lipometre, for the determination of the variation of light transmission across the plates as a function of the fat deposited on them. Results on 32 adults, males and females, show that the first four iterative samplings, at constant pressure, on the same forehead area follow an identical physical law independently of whether the skin is fatty or dry. This law affords a precise definition of the Casual-Level, its quantification and its correlation with skin patterns. It is consequently possible, either as an investigative or a routine technique, to predict the total amount of SSL with good accuracy within 2 min. The SSL, for non-pathological skins, fall within the range 150 microgram/cm2 to 900 microgram/cm2 which is in good agreement with values quoted in the literature.