Assessment of aging of the human skin by in vivo ultrasonic imaging.

The ultrasonic imaging technique that we have developed provides cross-sectional images of human skin in vivo with a resolution of about 80 microns axially (i.e., deep into the skin) and 250 microns lateral (parallel to the surface). In order to study aging skin, we obtained ultrasonic images from the mid-forearm (volar and dorsal sides) of 142 women. Ultrasonically, on the images, the dermis appears composed of two bands: a dark superficial one where the ultrasonic waves are propagated in a relatively homogeneous or non-echogenic medium, and a deeper one, which is lighter in color, suggesting a heterogeneous medium. Our results show that skin is thicker on the dorsal than on the volar forearm. In contrast to previously published results, skin thickness remains constant until the seventh decade of life, diminishing thereafter. The relative thickness of the two bands show marked variations with age: a progressive thickening of the dark band, from zero in infants to approximately 75% of total skin thickness in aged subjects, while the light band shows the inverse trend. Comparing the amplitude of the bands on the volar and dorsal forearm, the relative thickness of the dark band is larger on the dorsal (exposed) side and increases with age. These findings and the analysis of variously stained biopsies taken in some of our patients lead us to assign this dark band to a zone in the upper dermis where the collagen network is delicate, dense, and well organized. This is supported by some data in the literature. The thickness of this subepidermal non-echo-genic band appears to be a far more sensitive marker of skin aging at the dermal level than is the measurement of skin thickness.

Age-related mechanical properties of human skin: an in vivo study.

We have investigated in vivo how various viscoelastic parameters that describe the mechanical properties of the human skin may vary with age. Accordingly, we have used a mechanical device that records the torsional extensibility of the skin. When submitted to a low torque, the time-response curve of the skin affords the determination of the immediate extensibility (UE), the immediate recovery (UR), the viscoelastic part of the deformation (UV), the elastic recovery (UR/UE), and the creep relaxation time (tau). Because the skin thickness varies with age and primarily governs the mechanical properties, it was measured through an ultrasound technique at the same sites (forearm) where the torque was applied. The results show that the skin maintains its thickness and extensibility up to the seventh decade as opposed to its elasticity or recovery capacities, which decrease from an early age. The viscous part of the deformation is constant through life, whereas the creep relaxation time decreases linearily with age. Except for skin thickness, no differences in these parameters between men and women were detected. The significance of these results are discussed in terms of structure alterations. The determination of the elastic recovery (UR/UE) appears to be a parameter of choice for illustrating skin aging.

Effects of a new psoralen, 5-geranoxypsoralen, plus UVA radiation on murine ATPase positive Langerhans cells.

5-geranoxypsoralen (5-GOP), commonly called bergamottin, is a highly photoreactive psoralen, which in contrast to most furocoumarins, does not strongly interact with DNA. 5-GOP gives the opportunity to study, in a more selective way, the mechanisms of phototoxic and immunological activities induced by psoralen and UVA radiation. We investigated the effects of repetitive treatments with 5-GOP plus UVA radiation (320-400 nm) on the number of ATPase+ epidermal Langerhans cells and on the induction of photoreactivity. These effects were compared with those of 8-methoxypsoralen (8-MOP) or 5-methoxypsoralen (5-MOP) plus UVA radiation and UVA radiation alone. C3H/HeN mice were treated topically with the psoralen three times/week for 4 consecutive weeks followed each time by 1 J/cm2 of UVA radiation. At the end of the treatment, mice treated with 8-MOP or 5-MOP plus UVA radiation exhibited severe gross phototoxicity and nearly total depletion of ATPase-stained Langerhans cells. Both treatments produced severe morphological alterations of Langerhans cells. No gross but a microscopic phototoxic effect was observed after 5-GOP plus UVA radiation treatment, while the number of ATPase+ Langerhans cells was also greatly reduced. Interestingly the latter treatment induced no morphological alterations of the remaining Langerhans cells in contrast to treatment with 8-MOP or 5-MOP plus UVA radiation. We conclude that phototoxicity and decrease in the number of ATPase-stained epidermal immune cells observed after treatment with 5-GOP plus UVA radiation are not related to the DNA binding activity of the psoralen.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Skin care in childhood.

Childhood (3 to 9 years) is a calm period of constant growth throughout which social contacts are discovered and intelligence and discretion take place. Consequently, most diseases are infectious. Microrelief was found twice shallower and skin (epidermis + dermis) twice thinner than in adults. Intervals between furrows were reduced parallel to total body surface, thus ruling out the possible existence of special shelters favouring bacterial growth. Sweating is lower, as are skin surface lipid levels, in contrast to the post-natal period, inducing dryness of skin. Although total skin stiffness in vivo was found to be identical to young adult skin, skin chapping is much more frequent. Since detergents as well as extended hot baths may reduce the stratum corneum water binding capacity, they should be used with discretion. Hence, skin care in this period of age should be based upon different criteria than in adults.

Protective effect of trimethylpsoralen against UV-B erythema.

Vitiliginous patients undergoing photochemotherapy with TMP were less susceptible to a sun burn. To investigate this point, the MED for UV-B was measured before, 2 h, and 24 h after oral intake of TMP in 10 healthy volunteers. There was an increase of MED when UV exposure had taken place 2 h after TMP intake (P < 0.01). This was no longer detectable when the exposure had taken place 24 h after intake. MED increase was 11.8% for 0.19 mg/kg TMP, 21.0% for 0.37 mg/kg, and 23.7% for 0.74 mg/kg. This dose-dependence was significant (P < 0.01). The protective effect of TMP against UV-B erythema seemed related to UV absorption by the drug while it was in the blood stream.

Peak blistering point: influence on fluid levels of 5-MOP in human skin in vivo after systemic administration.

The concentration of 5-methoxypsoralen (5-MOP) in suction blister fluid (SBF) after oral intake was determined in relation to the peak blistering point. Interstitial fluid was obtained from nine healthy male volunteers by applying mild suction (300-350 mmHg) to the skin of the volar aspect of the forearm. Blisters were raised at three different times: 18 h prior to drug administration (group I); 2 h prior to drug administration (group II); and during drug ingestion (group III). SBF levels of 5-MOP were determined in each group of blisters 2 h after oral administration of 1.2 mg/kg micronized 5-MOP. The results showed a statistically significant difference in the concentrations of 5-MOP between each group of blisters. The highest concentration of 5-MOP in the SBF was found in group III and the lowest in group II blisters. These findings suggest that the point of peak blistering in relation to drug administration needs to be known in each pharmacological study using suction blisters.

Mechanical properties and Young's modulus of human skin in vivo.

The mechanical properties of the in vivo dermis were measured by means of a torque applied to the skin. The resulting deformation of 2-6 degrees, including the immediate and delayed visco-elastic components, as well as the relaxation were measured, and the raw values corrected for a constant skin thickness. The experiment performed on 138 individuals from 3 to 89 years old revealed a diminished elasticity and stretchability after the age of 30, associated with an increase in the visco-elastic component. The Young's modulus doubles with age. The results are discussed in terms of the various models proposed to explain dermal structure.

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.

Influence of ageing on the in vivo extensibility of human skin at a low stress.

The response of the forearm skin to a 9 . 10(-3) N . m torque was measured on 141 subjects aged 3-89 years. The results for each age class were adjusted to a skin thickness of 1 mm by use of a skinfold caliper. Results indicate a maximum skin thickness around the age of 40 years. Standardised skin extensibility decreases with age, the skin of females being less extensible than that of males. These results, which should be considered in relation to the total water content of the skin, are compared to those of other papers dealing with this subject.

An original procedure for quantitation of cutaneous resorption of sebum.

This paper describes an original in vivo device to investigate and quantify cutaneous resorption of sebum. Such a phenomenon was explored using a photometric determination of residual skin surface lipids at different times following initial deposits of known amounts of artificial sebum on demarcated areas. The technique was carried out on seven healthy subjects. The chosen area was the anterior aspect of the forearm, owing to the very low sebum production of this site, less than the sensitivity of the measuring instrument. The kinetics of absorption of applied sebum turned out to be hyperbolic-like and well correlated with experimental results (r = 0.992), allowing a mathematical determination of the initial velocity of penetration of sebum into the skin, reaching 20 micrograms/cm2.min for a standard program including a mean initial deposit of 116 micrograms/cm2. This kinetics actually does not fit with a true percutaneous absorption of lipids but is compatible with that of absorption into the stratum corneum. It conveys the faster absorption of the latter for sebum, a well-known but not so far quantified property of stratum corneum. The model here described is not at once transposable to skin areas with high sebum production since, quite obviously in such zones, the stratum corneum is permanently saturated with skin surface lipids. Therefore, the conclusions of this work cannot be correlated with the regreasing parameters studied so far on the forehead, but they provide interesting data about the evolution of sebum following its output onto the skin surface and therefore a better understanding of sebaceous physiology.

Treatment of psoriasis with a new micronized 5-methoxypsoralen tablet and UVA radiation.

Since 1974, phototherapy with psoralen and ultraviolet A (UVA) has been used successfully for the treatment of psoriasis. However, undesirable side effects, including phototoxicity, nausea, stomach pain and headaches, have led investigators to develop new psoralen compounds. 5-Methoxypsoralen (5-MOP) has thus been introduced as an alternative to 8-MOP because of its less pronounced side effects. Since the absorption kinetics and bioactivity of 5-MOP are known to be variable, a new micronized tablet form (5-MOPm) has been developed. In an open randomized study, oral treatments with 5-MOP or 5-MOPm plus UVA radiation were compared in 22 psoriatic patients. Skin type and initial psoriasis area severity index did not differ significantly between treatment groups. Serum concentrations were significantly higher (320 vs 85.82 ng/ml) and occurred earlier (51.8 vs 229.09 min) with 5-MOPm. In addition, a reduction in PASI of more than 90% was achieved sooner (10.63 vs 17.27 treatments) and with a lower cumulative UVA dose (145.89 vs 232.11 J/cm2), in the group treated with 5-MOPm. No side effects were observed with 5-MOPm. Our data indicate that 5-MOPm has a higher bioavailability, clinical efficacy and tolerability than the commonly used 5-MOP.

Comparative electron microscopic study of clear cells in epidermodysplasia verruciformis and flat warts.

Are Epidermodysplasia verruciformis (E.V.) and disseminated flat warts different diseases? Are there any diagnostic criteria between them? In order to attempt answering these 2 questions, fundamental for prognosis and nosology, a comparative ultrastructural study was made of epidermal clear cells of 2 cases of E.V. and 4 flat warts from 4 patients of whom 3 were under immunosuppression drugs. The reason of cytoplasmic electron translucency was mainly a reduction in tonofilaments and keratohyalin amounts in E.V. and a centrifugal edema and vacuolization in flat warts. On the other hand, the number of ribosomes was raised in E.V. and reduced in flat warts. These findings allow differentiation between the 2 diseases and suggest a possible different host-virus relationship.

Comparative electron microscopic study of clear cells in epidermodysplasia verruciformis and flat warts.

Are Epidermodysplasia verruciformis (E.V.) and disseminated flat warts different diseases? Are there any diagnostic criteria between them? In order to attempt answering these 2 questions, fundamental for prognosis and nosology, a comparative ultrastructural study was made of epidermal clear cells of 2 cases of E.V. and 4 flat warts from 4 patients of whom 3 were under immunosuppression drugs. The reason of cytoplasmic electron translucency was mainly a reduction in tonofilaments and keratohyalin amounts in E.V. and a centrifugal edema and vacuolization in flat warts. On the other hand, the number of ribosomes was raised in E.V. and reduced in flat warts. These findings allow differentiation between the 2 diseases and suggest a possible different host-virus relationship.

Action of trypsin on human plantar stratum corneum. An ultrastructural study.

Incubation of human plantar stratum corneum (SC) with trypsin at various pH suppressed the typical "keratin pattern" in the cytoplasm of the horny cells and disclosed tonofilaments and desmosomal attachment plates as they are seen in living keratinocyts. Tonofilaments were 62-75 A wide and showed a 100-120 A periodicity. This effect was non-specific since it was also obtained by incubation of SC with citric acid or sodium citrate, but it was not due to hydration alone. Partial acantholysis was obtained by incubation with trypsin followed by citric acid. After simultaneous action of trypsin in sodium citrate and in citric acid, cell membranes were separated from the cytoplasm and many of them were broken around desmosomes with subsequent isolation of desmosomes. The role of trypsin in this effect was uncertain. These findings strongly suggest that the filamentous network built up by living keratinocytes remains almost unchanged during the keratinization process although no longer visible under E.M.

Heterogeneous keratohyalin formation in warts.

The heterogenecity of keratohyalin (KH) has been demonstrated in rats, then in human warts where similar morphological features have been found and among them, dense homogeneous ovoïd single granules (SG) and composite granules (CG) apparently made up of single granules "coated" with a matrix. This work compares the ultrastructure of the KH of the tongue of newborn rats with that of common warts with and without post-fixation by OsO4, after oxydation by H2O2 and after pepsin treatment. The osmiophily of the SG is confirmed as well as the absence of osmiophily of the matrix of the CG. In man, however, the SG are resistant to oxydation by H2O2 and the CG matrix is oxydation sensitive whereas the opposite is observed in the case of rats. These differences show that it is impossible to deduce the composition of the KH in human warts from that of the rat despite their close ultrastructural resemblance but that important modification of the keratogenesis and KH formation are induced in the cells parasited by the virus of common warts.

Effect of a conjugated oestrogen (Premarin) cream on ageing facial skin. A comparative study with a placebo cream.

The effects of Premarin cream on ageing facial skin were studied in a randomised, double-blind, parallel group study. Fifty-four women aged 52-70 years who had moderate to severe facial cutaneous ageing, applied 1 g of either Premarin cream (0.625 mg conjugated oestrogens per gram of cream), or placebo cream (same composition with the exclusion of conjugated oestrogens) to the face nightly for 24 weeks. Each morning these women protected their face with a sunblock SPF 15. Skin thickness was measured by B-scan ultrasonic echography, and skin microrelief by profilometry. Each subject's facial appearance was also evaluated by the subject herself and by the clinician. A statistically significant difference (P = 0.013) in favour of Premarin cream was detected in skin thickness at week 24. Skin thickness (dermal plus epidermal) for the women who used Premarin cream increased from 1.56 +/- 0.20 mm at baseline to 1.68 +/- 0.19 mm, compared with 1.52 +/- 0.20 mm at baseline to 1.59 +/- 0.19 mm in the placebo group. Premarin cream was also significantly more effective than placebo cream in improving fine wrinkles according to the results at weeks 12 and 24 (P = 0.010 and P = 0.012, respectively). Significant improvement from baseline was detected in both groups for roughness, laxity and mottled pigmentation and/or lentigines; however, there was no significant difference in these parameters between the two treatment groups. No subjects discontinued treatment for a safety reason. In conclusion, Premarin cream produced better results than the placebo cream; the difference was statistically significant for skin thickness and fine wrinkles. Premarin cream was well tolerated locally, and its general safety was good.

A new technique to study the mechanical properties of collagen lattices.

A new technique to study the mechanical properties of collagen lattices or dermal equivalents is described. With the help of the load-extension curve obtained with a uniaxial traction apparatus, a stiffness modulus varying from 0.06 to 1 MPa is calculated from the studied parameters (duration of culture, collagen and fibroblast concentration). The technique is presented as a new tool for testing the effect of pharmacological agents on the mechanical properties of the skin.

Surface recovery and stripping methods to quantify percutaneous absorption of caffeine in humans.

The percutaneous absorption of caffeine from two vehicles, an emulsion and an acetone solution, was quantified by in vivo techniques in humans. A surface recovery technique over a 6-h application and a stripping method after a 30-min application were performed on the volar aspect of the forearm on 12 volunteers. Caffeine was assessed by HPLC. Two phases were distinguished in the percutaneous absorption of caffeine: a higher filling up of the stratum corneum with the oil-in-water emulsion than with the acetone solution, which was then followed by a steady-state flux corresponding to the penetration in the living tissues. The permeability constants (Kp) with emulsion and acetone were 1.59 x 10(-4) and 9.53 x 10(-8) cm/h, respectively. The stripping method showed concentrations of caffeine in stratum corneum that were five times higher with emulsion (212 ng/cm2) than with acetone (37 ng/cm2). With acetone as a vehicle, approximately 40% of caffeine of the cornfield layer was found around the treated area. This sizeable lateral spread within the stratum corneum was not observed with the emulsion.

Dermatological autoimmune diseases and the multiple autoimmune syndromes.

The association of autoimmune pathologies with cutaneous diseases has received little attention, except for their association by twos. The combination of at least three autoimmune diseases in a same patient has recently been defined as a Multiple Autoimmune Syndrome (MAS). The purpose of this article is to define the place of dermatological autoimmune conditions (vitiligo, alopecia areata, pemphigus, bullous pemphigoid, dermatitis herpetiformis) among the MAS and to stress the clinical aspects that may aid dermatologists in the care of their patients.