Validation of a new in vitro Sun Protection Factor method to include a wide range of sunscreen product emulsion types.

In 2017, Cosmetics Europe performed a double-blinded ring test of 24 emulsion-type sunscreen products, across 3 in vivo test laboratories and 3 in vitro test laboratories, using a new candidate in vitro SPF test method. Based on the results of this work, an article was published showing how data derived from a new lead candidate method conform to new International Standards (ISO) acceptance criteria for alternative SPF test methods (Any alternative method should consider the matrix effect and if required, specify the matrix applicability of the method; Criterion 1a: Systematic differences between methods should be negligible: 95% of all individual results of an alternative method are within the range of ±2× reproducibility standard deviation of the in vivo method, that is overall bias must be below 0.5× reproducibility standard deviation of the in vivo method; Criterion 1b: Measurement uncertainty of an alternative method should be below the measurement uncertainty of the in vivo method. Candidate method predicted values must fall within the full 'funnel' (SPF 6-50+) limits proposed by Cosmetics Europe (derived from the same minimum test design, that is using the ISO24444 Method to measure at least 24 products across at least 3 laboratories using at least 5 test subjects/laboratory, in a blinded fashion).). Of the 24 sunscreen products tested, the majority of emulsions were of the oil-in-water (O/W) type, whereas only one was water-in-oil (W/O) and there were no products with a mineral-only sun filter system. In order to confirm the scope of this method, therefore, a new study was conducted that included 73 W/O (12 mineral + organic, 44 mineral only and 17 organic only) and 3 O/W mineral-only, emulsion-type sunscreen products (a total of 76 new sunscreen products). When combined with the previous 24 products (tested in 3 different laboratories), this yielded a new data set comprising a total of 100 emulsion-type sunscreen products, with SPF values ranging from 6 to 50+ (with a total of 148 data points). These products were tested using the double-plate in vitro SPF test method and compared with the ISO TC217/WG7 acceptance criteria for alternative SPF test methods. Over 95% of paired in vitro: in vivo SPF values lay within the upper and lower limits of the ISO acceptance criteria funnel, with no bias. This new in vitro SPF test method, therefore, meets the minimum requirements for an alternative SPF test method to ISO24444:2010, for emulsion-type sunscreen products (which make up the majority of marketed sunscreen products).

En 2017, Cosmetics Europe a réalisé un ring test en double aveugle de 24 produits de protection solaire de type émulsion, dans 3 laboratoires de test in vivo et 3 laboratoires de test in vitro, en utilisant une nouvelle méthode de test SPF in vitro. Sur la base des résultats de ces travaux, un article a été publié montrant comment les données dérivées de cette nouvelle méthode sont conformes aux nouveaux critères d'acceptation des normes internationales (ISO) pour les méthodes de test SPF alternatives. Sur les 24 produits de protection solaire testés, la majorité des émulsions étaient du type huile dans l'eau (H / E), tandis qu'un seul était de l'eau dans l'huile (E / H) et il n'y avait aucun produit contenant uniquement des minéraux. Afin de confirmer cette méthode, une nouvelle étude a donc été menée comprenant 73 produits E/ H (12 produits contenant des filtres minéraux + organiques, 44 produits contenant des filtres minéraux uniquement et 17 produits contenant des filtres organiques uniquement) et 3 produits H / E contenant des filtres minéraux uniquement, tous de type émulsion (donc un un total de 76 nouveaux produits de protection solaire). Combiné aux 24 produits précédents (testés dans 3 laboratoires différents), cela a donné un nouvel ensemble de données comprenant un total de 100 produits de protection solaire de type émulsion, avec des valeurs SPF allant de 6 à 50+ (avec un total de 148 points de données) . Ces produits ont été testés à l'aide de la méthode de test SPF in vitro double approche et comparés aux critères d'acceptation de l'ISO TC217 / WG7 pour les méthodes alternatives du SPF in vivo. Plus de 95% des valeurs de SPF appariées in vitro: in vivo se situent dans les limites supérieure et inférieure de l'entonnoir des critères d'acceptation ISO, sans biais. Cette nouvelle méthode de test SPF in vitro, par conséquent, répond aux exigences minimales d'une méthode de test SPF alternative à ISO24444: 2010, pour les produits de protection solaire de type émulsion (qui constituent la majorité des produits de protection solaire commercialisés).

Anti-inflammatory / anti-oxidant activity of ingredients of sunscreen products? Implications for SPF.

OBJECTIVE: The Sun Protection Factor (SPF) of sunscreen products is derived from testing in vivo their ability to prevent erythema ("sunburn"). Recently, certain articles have raised concerns that sunscreen products may actively suppress erythema via anti-inflammatory / anti-oxidant (AI/AO) activity. These articles reason that this may result in a higher labelled SPF value than that provided by the efficacy of the UVR filters alone, giving consumers a "false sense of security". On the other hand, since inflammatory processes are known to play a role in the mechanisms of photodamage / skin cancer induction and propagation, AI/AO activity may provide valuable incremental photoprotective benefit (provided that there is no interference with visible erythema). The objective of these studies, therefore, was to investigate the potential of AI/AO ingredients to suppress UVR-induced erythemal response in human skin, in vivo. METHODS: In vivo studies with SPF30 sunscreen formulations containing a variety of AI/AO ingredients were performed according to the International Standard ISO24444:2010 method. While ISO24444:2010 requires assessment of erythema at 20 ± 4h post-irradiation, an additional assessment at 5 h post-irradiation was also used to determine potential delay in erythema development. RESULTS: None of the formulations, containing a variety of AI/AO ingredients, influenced SPF determination in comparison to the vehicle formulation. CONCLUSION: Our in vivo results demonstrate that commonly-used AI/AO ingredients, at concentrations typically used in sunscreen products, neither influence SPF value nor delay erythemal response, i.e., the measured SPF reflects the true photoprotective capacity of the product.

OBJECTIF: Le facteur de protection solaire (SPF) des produits de protection solaire est dérivé de tests in vivo servant à déterminer leur capacité à prévenir un érythème (« coup de soleil ¼). Récemment, certains articles ont soulevé des inquiétudes en insinuant que les produits de protection solaire pourraient activement faire disparaître un érythème par le biais d'une activité anti-inflammatoire/anti-oxydante (AI/AO). Ces articles soutiennent que cela pourrait impliquer une valeur déclarée du SPF plus élevée que celle fournie par l'efficacité des filtres RUV à eux seuls, donnant ainsi une « fausse impression de sécurité ¼ aux consommateurs. D'autre part, étant donné que les processus inflammatoires sont réputés jouer un rôle dans les mécanismes de photo-altération/d'induction et de propagation du cancer de la peau, l'activité AI/AO pourrait apporter un précieux bénéfice photo-protecteur amplifié (à condition qu'il n'y ait aucune interférence avec un érythème visible). L'objectif de ces études était, par conséquent, d'étudier le potentiel des ingrédients contribuant à l'activité AI/AO à faire disparaître la réponse érythémateuse induite par les RUV dans la peau humaine, in vivo. MÉTHODES: Des études in vivo avec des formules de produits solaires à SPF30 contenant une variété d'ingrédients contribuant à l'activité AI/AO ont été effectuées conformément à la méthode correspondant à la norme internationale ISO24444:2010. Bien que l'ISO24444:2010 nécessite l'évaluation de l'érythème à 20 _ 4 heures post-irradiation, une évaluation supplémentaire à 5 heures post-irradiation a également été utilisée pour déterminer l'éventuel délai d'apparition d'un érythème. RÉSULTATS: Aucune des formules, contenant une variété d'ingrédients contribuant à l'activité AI/AO, n'a influencé la détermination du SPF par comparaison à la formule véhicule. CONCLUSION: Nos résultats in vivo démontrent que les ingrédients contribuant à l'activité AI/AO fréquemment utilisés, aux concentrations généralement utilisées dans les produits de protection solaire, n'influencent pas la valeur du SPF, pas plus qu'ils ne retardent la réponse érythémateuse, autrement dit, le SPF mesuré reflète la véritable capacité photo-protectrice du produit.

Validation of an in vitro sun protection factor (SPF) method in blinded ring-testing.

OBJECTIVE: The objective of this work was to investigate the utility of a new in vitro SPF test method in blinded ring-testing, against new ISO acceptance criteria. METHODS: Twenty four blinded, commercial, emulsion-type, primary sunscreen products, covering the full range of labelled SPF in Europe (SPF6 - 50+), were tested by three test institutes using the current ISO24444:2010 In Vivo SPF Test Method and simultaneously by three separate test laboratories using a new candidate in vitro SPF test method, developed under the leadership of Cosmetics Europe (CE). The resulting relationship between in vitro SPF and in vivo SPF values was then compared with acceptance criteria developed recently by the International Standards (ISO) TC217/WG7 Sun Protection Test Methods Working Group. RESULTS: Analysis of the mean inter-laboratory in vitro and mean inter-institute in vivo SPF values revealed a strong correlation between in vitro and in vivo values, with a Pearson correlation coefficient of r2  = 0.88 (P < 0.0001), a slope of 1.01 and a non-significant intercept (-1.48; P = 0.62). When these data were compared to the new ISO WG7 acceptance criteria, method bias was found to be extremely low and over 95% of the coupled data lay within the model 'funnel' (defined by upper and lower confidence intervals). CONCLUSION: In conclusion, the results of blinded ring testing and comparison to new ISO WG7 acceptance criteria indicate that a new in vitro SPF test method meets (and exceeds) these minimum criteria and is an interesting candidate for possible deployment as an industry test methodology.

The effect of skin surface topography and skin colouration cues on perception of male facial age, health and attractiveness.

OBJECTIVE: Previous studies investigating the effects of skin surface topography and colouration cues on the perception of female faces reported a differential weighting for the perception of skin topography and colour evenness, where topography was a stronger visual cue for the perception of age, whereas skin colour evenness was a stronger visual cue for the perception of health. We extend these findings in a study of the effect of skin surface topography and colour evenness cues on the perceptions of facial age, health and attractiveness in males. METHODS: Facial images of six men (aged 40 to 70 years), selected for co-expression of lines/wrinkles and discolouration, were manipulated digitally to create eight stimuli, namely, separate removal of these two features (a) on the forehead, (b) in the periorbital area, (c) on the cheeks and (d) across the entire face. Omnibus (within-face) pairwise combinations, including the original (unmodified) face, were presented to a total of 240 male and female judges, who selected the face they considered younger, healthier and more attractive. RESULTS: Significant effects were detected for facial image choice, in response to skin feature manipulation. The combined removal of skin surface topography resulted in younger age perception compared with that seen with the removal of skin colouration cues, whereas the opposite pattern was found for health preference. No difference was detected for the perception of attractiveness. These perceptual effects were seen particularly on the forehead and cheeks. Removing skin topography cues (but not discolouration) in the periorbital area resulted in higher preferences for all three attributes. CONCLUSION: Skin surface topography and colouration cues affect the perception of age, health and attractiveness in men's faces. The combined removal of these features on the forehead, cheeks and in the periorbital area results in the most positive assessments.

A randomized controlled trial to evaluate the effect of a new skincare regimen on skin barrier function in those with podoconiosis in Ethiopia.

BACKGROUND: Podoconiosis affects an estimated 3 million people in Ethiopia with a further 19 million at risk. Volcanic soil and pathogens enter skin breaches in the feet causing inflammation, lymphoedema and hyperkeratosis. There is no robust evidence on optimal podoconiosis skincare regimens to improve skin barrier function (SBF). OBJECTIVES: To evaluate the effectiveness of a new, low-cost, evidence-based intervention to improve SBF in the lower limbs of those with podoconiosis. METHODS: A randomized controlled trial (NCT02839772) was conducted over 3 months in two podoconiosis clinics (n = 193). The intervention comprised 2% (v/v) glycerine added to a reduced volume of soaking water. The control group received the current skincare regimen. Primary outcome measures were transepidermal water loss (TEWL) and stratum corneum hydration (SCH) at four specific sites on the lower limbs. RESULTS: Improvement in SBF was observed in both groups across all measurement sites and time points, although this was significantly greater in the experimental group. TEWL reduced in both groups at all sites. For example, on top of the foot the estimated group difference in TEWL at visit 4 was 1·751 [standard error (SE) = 0·0390] in favour of the experimental group [t = 3·15, degrees of freedom (df) = 189·58, P = 0·002, 95% confidence interval (CI) 0·066-2·85], indicating a greater reduction in TEWL in the experimental group. Similarly, at the same site the estimated group difference in SCH at visit 4 was -2·041 (SE = 0·572) in favour of the experimental group (t = -3·56, df = 186·74, P < 0·001, 95% CI -3·16 to -0·91), indicating a greater increase in SCH in the experimental group. There were also significantly greater reductions in odour, number of wounds and largest foot circumference in the experimental vs. the control group. CONCLUSIONS: The addition of 2% (v/v) glycerol to a reduced volume (83% reduction) of soaking water significantly improved SBF.

Hexamidine salts - applications in skin health and personal care products.

Hexamidine (HEX) has been used as a preservative in topical preparations since the 1950s. A number of studies also indicate that the molecule plays a beneficial role in skin homoeostasis. In this review, we describe the physicochemical properties of hexamidine diisethionate (HEX D) and the corresponding hydrochloride salt (HEX H). The biocidal and protease inhibition properties of HEX are outlined as well as the effects of HEX on lipid processing enzymes, corneocyte maturity, stratum corneum thickness and transepidermal water loss (TEWL). Skin permeation properties of HEX D and HEX H are summarized, and formulation approaches for effective dermal targeting of HEX are discussed.

Randomized, double-blinded, vehicle-controlled, split-face study to evaluate the effects of topical application of a Gold Silk Sericin/Niacinamide/Signaline complex on biophysical parameters related to skin ageing.

OBJECTIVE: To investigate the effects of topical application of a Gold Silk Sericin (GSS) complex on biophysical parameters related to skin ageing. METHODS: A range of non-invasive bioengineering methods were deployed in an 8-week randomized, double-blinded, vehicle-controlled, split-face study among 40 female subjects aged 40-70. Endpoints measured included expert grades of skin condition, stratum corneum (SC) hydration, SC barrier function, elasticity and surface topography. RESULTS: The GSS complex produced significant single-variable (P < 0.05) improvements in SC hydration, barrier function, elasticity and surface topography compared with the Vehicle control. CONCLUSION: The GSS complex examined in this study represents an interesting new cosmetic topical technology with which to address multiple aspects of aged/photoaged female facial skin.

In vitro-in vivo correlation in skin permeation.

PURPOSE: In vitro skin permeation studies have been used extensively in the development and optimisation of delivery of actives in vivo. However, there are few reported correlations of such in vitro studies with in vivo data. The aim of this study was to investigate the skin permeation of a model active, niacinamide, both in vitro and in vivo. METHODS: Conventional diffusion cell studies were conducted in human skin to determine niacinamide permeation from a range of vehicles which included dimethyl isosorbide (DMI), propylene glycol (PG), propylene glycol monolaurate (PGML), N-methyl 2-pyrrolidone (NMP), Miglyol 812N® (MG), and mineral oil (MO). Single, binary or ternary systems were examined. The same vehicles were subsequently examined to investigate niacinamide delivery in vivo. For this proof-of-concept study one donor was used for the in vitro studies and one volunteer for the in vivo investigations to minimise biovariability. Analysis of in vitro samples was conducted using HPLC and in vivo uptake of niacinamide was evaluated using Confocal Raman spectroscopy (CRS). RESULTS: The amount of niacinamide permeated through skin in vitro was linearly proportional to the intensity of the niacinamide signal determined in the stratum corneum in vivo. A good correlation was observed between the signal intensities of selected vehicles and niacinamide signal intensity. CONCLUSIONS: The findings provide further support for the use of CRS to monitor drug delivery into and across the skin. In addition, the results highlight the critical role of the vehicle and its disposition in skin for effective dermal delivery.

Assessment of skin barrier function in podoconiosis: measurement of stratum corneum hydration and transepidermal water loss.

BACKGROUND: Podoconiosis is a common cause of lymphoedema in barefoot workers in Ethiopia and other countries. It has severe consequences for patients' physical function, quality of life and economic status. AIMS: To investigate stratum corneum (SC) hydration and transepidermal water loss (TEWL) in patients with podoconiosis compared with controls. METHODS: In total, 55 patients and 20 controls were recruited. For each study subject, SC and TEWL measurements were taken, along with foot and lower leg circumferences. Measurements were compared between the patient and control groups. RESULTS: Foot circumferences tended to be higher in patients with podoconiosis, with the mean foot:leg circumference ratio being 1·19 (95% confidence interval 1·11-1·28) times that for controls (P = 0·001). There was no detectable difference between patients and controls in TEWL values (P > 0·05); however, SC hydration was significantly lower in patients vs. controls for the foot (P = 0·004) and lower leg (P = 0·046) sites. CONCLUSIONS: Patients with podoconiosis have significantly lower SC hydration in the skin of their lower legs and feet than controls, which may lead to cracking and splitting, and increased risk of lymphoedema and infection.

Influence of niacinamide containing formulations on the molecular and biophysical properties of the stratum corneum.

Niacinamide-containing moisturisers are known be efficacious in alleviating dry skin conditions and improving stratum corneum (SC) barrier function. However, the mechanisms of action of niacinamide at the molecular level in the SC are still not well understood. Previously, we have reported the development of novel methods to probe SC barrier properties in vivo. The aim of the present study was to characterise changes in Trans Epidermal Water Loss (TEWL), corneocyte surface area and maturity, selected protease activities and SC thickness after repeated application of a simple vehicle containing niacinamide. A commercial formulation was also included as a reference. The left and right mid-volar forearms of 20 healthy volunteers were used as study sites, to which topical formulations were applied twice daily for 28 days. After successive tape-stripping, corneocyte maturity and surface area were assessed. In addition, activity of the desquamatory kallikrein (KLK) protease enzymes KLK5 and KLK7, and tryptase and plasmin (implicated in inflammatory process) were measured using a fluorogenic probe assay. The amount of protein removed and TEWL were also recorded. SC thickness before and after treatment was determined using Confocal Raman Spectroscopy (CRS). Overall (i) corneocyte maturity and surface area decreased with increasing number of tape strips, (ii) activity of both the desquamatory and inflammatory enzymes was highest in the outer layers of the SC and decreased with depth (iii) TEWL increased as more SC layers were removed. Furthermore, areas treated with formulations containing niacinamide were significantly different to pre-treatment baseline and untreated/vehicle-control treated sites, with larger and more mature corneocytes, decreased inflammatory activity, decreased TEWL and increased SC thickness. These data (a) confirm the utility of measures and metrics developed previously for the non-invasive assay of SC barrier function, (b) present an holistic picture of a SC compartment managing barrier function through dynamic optimisation of pathlength and quality of building materials used, and (c) shed new light on niacinamide as a topical formulation adjunct with unique SC barrier-augmentation properties.

Comparison of gravimetric and spectroscopic approaches to quantify stratum corneum removed by tape-stripping.

Skin surface tape-stripping is an extensively used technique to examine the distribution profile, penetration and safety of various active compounds. It is also a widely accepted method to probe skin barrier properties and more specifically, those of the stratum corneum (SC). The amount of SC removed by tape-stripping is generally determined either gravimetrically or by extraction and measurement of SC proteins. A novel infra-red densitometry (IRD) technique has recently been introduced to measure SC protein content. In the present study, IRD was investigated as an alternative method to measure the mass of SC removed by tape-stripping. Tape-stripping experiments were conducted on human volunteers. The weight of the stratum corneum removed was assessed by the gravimetric approach and by IRD. Transepidermal water loss (TEWL) was also measured before and after each tape-strip. A linear correlation coefficient was obtained for the data from the gravimetric and IRD measurements (r(2)=0.65; n=240). IRD is therefore proposed as a rapid, non-destructive alternative to the gravimetric approach to estimate the amount of SC removed by tape-stripping in vivo.

Visible skin colouration predicts perception of male facial age, health and attractiveness.

Although there is evidence that perception of facial age, health and attractiveness is informed by shape characteristics as well as by visible skin condition, studies on the latter have focused almost exclusively on female skin. Recent research, however, suggests that a decrease in skin colour homogeneity leads to older, less healthy and less attractive ratings of facial skin in both women and men. Here, we elaborate on the significance of the homogeneity of visible skin colouration in men by testing the hypothesis that perception of age, health and attractiveness of (non-contextual) digitally isolated fields of cheek skin only can predict that of whole facial images. Facial digital images of 160 British men (all Caucasian) aged between 10 and 70 were blind-rated for age, health and attractiveness by a total of 147 men and 154 women (mean age = 22.95, SD = 4.26), and these ratings were related to those of corresponding images of cheek skin reported by Fink et al. (J. Eur. Acad. Dermatol. Venereol. in press). Linear regression analysis showed that age, health and attractiveness perception of men's faces could be predicted by the ratings of cheek skin only, such that older men were viewed as older, less healthy and less attractive. This result underlines once again the potent signalling role of skin in its own right, independent of shape or other factors and suggests strongly that visible skin condition, and skin colour homogeneity in particular, plays a significant role in the perception of men's faces.

Colour homogeneity and visual perception of age, health and attractiveness of male facial skin.

BACKGROUND: Visible facial skin condition in females is known to affect perception of age, health and attractiveness. Skin colour distribution in shape- and topography-standardized female faces, driven by localized melanin and haemoglobin, can account for up to twenty years of apparent age perception. Although this is corroborated by an ability to discern female age even in isolated, non-contextual skin images, a similar effect in the perception of male skin is yet to be demonstrated. OBJECTIVES: To investigate the effect of skin colour homogeneity and chromophore distribution on the visual perception of age, health and attractiveness of male facial skin. METHODS: Cropped images from the cheeks of facial images of 160 Caucasian British men aged 10-70 years were blind-rated for age, health and attractiveness by a total of 308 participants. In addition, the homogeneity of skin images and corresponding eumelanin/oxyhaemoglobin concentration maps were analysed objectively using Haralick's image segmentation algorithm. RESULTS: Isolated skin images taken from the cheeks of younger males were judged as healthier and more attractive. Perception of age, health and attractiveness was strongly related to melanin and haemoglobin distribution, whereby more even distributions led to perception of younger age and greater health and attractiveness. The evenness of melanized features was a stronger cue for age perception, whereas haemoglobin distribution was associated more strongly with health and attractiveness perception. CONCLUSIONS: Male skin colour homogeneity, driven by melanin and haemoglobin distribution, influences perception of age, health and attractiveness.

Influence of Aqueous Cream BP on corneocyte size, maturity, skin protease activity, protein content and transepidermal water loss.

BACKGROUND: Aqueous Cream BP is frequently prescribed for patients with eczema and is known to induce sensitivity in certain patients and also to decrease the thickness of the stratum corneum (SC). We have previously reported methodology to quantify corneocyte maturity and size, protease activity and protein content within different levels of the SC. OBJECTIVES: The aim of the present study was to investigate changes in corneocyte size, corneocyte maturity, selected protease activities, protein content and transepidermal water loss (TEWL) in normal skin after a 28-day application of Aqueous Cream BP. METHODS: The left and right mid volar forearms of six healthy female volunteers were selected as the study sites. Aqueous Cream BP was applied twice daily to treated sites for 28 days. At the end of this period, the site was tape-stripped and corneocyte maturity, corneocyte size and protease activity of the desquamatory kallikrein proteases, KLK5 and KLK7, and the inflammatory proteases tryptase and plasmin were measured. Protein content and TEWL measurements were also recorded. RESULTS: Corneocyte maturity and size decreased with increasing number of tape strips, and were significantly lower in treated sites compared with untreated sites. Protease activity and TEWL values were higher (P < 0·05) for the treated sites compared with untreated sites. The amount of protein removed from deeper layers of treated sites was significantly lower than from untreated sites. CONCLUSIONS: We report rapid minimally invasive measures of the effects of Aqueous Cream BP at the cellular and molecular level of the skin. Treatment with this formulation is associated with increased desquamatory and inflammatory protease activity. Changes in corneocyte maturity and size are also indicative of accelerated skin turnover induced by chronic application of this emollient. These findings question firmly the routine prescription of this preparation as a moisturizer in patients with atopic dermatitis.

Depth profiling of stratum corneum biophysical and molecular properties.

BACKGROUND: The barrier function of the skin may be characterized by a number of biophysical and molecular methods. Variation in the barrier properties as a function of depth has not been explored in detail. OBJECTIVES: To characterize changes in corneocyte surface area, corneocyte maturity, selected protease activities and transepidermal water loss (TEWL) in the ventral forearm with increasing depth. METHODS: The left mid-ventral forearm of 22 healthy volunteers was selected as the study site. After tape stripping, corneocyte maturity and surface area were assessed. The protease activity of the desquamatory kallikrein proteases, KLK5 and KLK7, and inflammatory tryptase was measured using a fluorogenic probe assay. Protein content and TEWL were also recorded. RESULTS: Corneocyte maturity and surface area decreased with increasing number of tape strippings, i.e. depth into the skin. More mature corneocytes were typically larger than less mature corneocytes. The protease activities of both the desquamatory and inflammatory enzymes together with the protein content were highest in the outer layers of the stratum corneum and decreased with depth. As expected, TEWL increased as more stratum corneum layers were removed. There were no statistical differences between men and women or caucasian and black subjects for all of the parameters studied. CONCLUSIONS: The techniques used in this study provide rapid noninvasive measures of the spatial distribution of corneocyte maturity and surface area as well as protease activity and protein content within different levels of the stratum corneum layers. The methods used will allow mechanistic insight into the effects of formulation excipients and active ingredients on epidermal turnover and skin barrier function.

Differences in visual perception of age and attractiveness of female facial and body skin.

Perception of age and health is critical in the judgement of attractiveness. The few studies conducted on the significance of apparent skin condition on human physical appearance have studied faces alone or isolated fields of images facial skin. Little is known about whether perception of the face matches that of other body parts or if body skin affects overall age and attractiveness perception when presented in combination with facial skin. We hypothesized that independent presentation of female faces, chests and arms (including hands) - cropped from a full face and upper body image - would result in significant differences in perception of age and attractiveness compared to the corresponding composite. Furthermore, we sought to investigate whether relatively young and attractive looking skin on selected, individual parts of the body affects overall perception. Digital photographs of 52 women aged 45-65 years were collected and processed to yield four derivative sets of images: One set showed the composite of all features, i.e. the face, the chest and the arms, whereas the other three were cropped carefully to show each part of the upper body described above independently. A total of 240 participants judged these faces for perceived age and attractiveness. Our results showed significant differences in perception with the chest and the arms being judged significantly younger than the face or composite image of the same women. Moreover, arms and chest images were perceived as more attractive than face and composite images. Finally, regression analysis indicated that differences between the perceived and chronological values of overall age perception could be predicted by age perception of the face and arms. These results continue to support the significance of facial age perception in assessment of a woman's age, but highlight that body skin also plays a role in overall age impression.

The COLIPA in vitro UVA method: a standard and reproducible measure of sunscreen UVA protection.

There is a continuing need to measure and communicate reliably the UVA protection offered by commercial sunscreens. To that end, the COLIPA (European Cosmetics Trade Association) 'In Vitro Sun Protection Methods' group has developed a new in vitro method for measuring UVA protection in a standardized, reproducible manner. The method is based on in vitro UV substrate spectrophotometry and convolution of resulting absorbance data with the action spectrum for the in vivo Persistent Pigment Darkening (PPD) endpoint to provide an in vitro UVA protection factor (UVAPF) which is correlated with an in vivo measure. This method has been published as a COLIPA guideline, used currently in European geographies for testing and labelling sunscreen products. This article summarizes two 'ring' studies, involving eight separate testing laboratories, which both defined critical parameters for the method and validated it. In Ring Study 1, eight laboratories tested the in vitro UV transmission of a total of 24 sunscreens and, from the data, a unit dose of UVA (D(0) of 1.2 J cm(-2)) was defined to provide a single irradiation step which, by taking into account potential sunscreen photo-instability, gave the closest agreement with in vivo UVAPF values. In Ring Study 2, eight laboratories tested the in vitro UV transmission of a total of 13 sunscreens using this single irradiation step and established a very good correlation (r(2) = 0.83; slope = 0.84, P < 0.0001) between resulting in vitro UVAPF values and corresponding values derived from the in vivo PPD method. This new method, therefore, can be used to provide a reliable in vitro metric to describe and label UVA efficacy in sunscreen products, in line with the EU Commission recommendation 2006/247/EC.

Visible skin condition and perception of human facial appearance.

Evolutionary psychology suggests that certain human beauty standards have evolved to provide reliable cues of fertility and health. Hence, preferences for some physical characteristics of the face and body are thought to reflect adaptations for the promotion of mate choice. Studies that have investigated facial attractiveness have concentrated mainly on features such as symmetry, averageness and sex-typical traits, which are developed under the influence of sex steroids. Few studies, however, have addressed the effect of human skin condition on perception of facial appearance in this context, and possible implications for sexual selection. There is now accumulating evidence that skin pigmentation and skin surface topography cues, particularly in women, have a significant influence on attractiveness judgements, as they seem primarily to signal aspects of age and health. This article (i) reviews briefly some of the main determinants of visible skin condition, (ii) presents recent evidence on its signalling value in face perception and (iii) suggests areas for future research with reference to an evolutionary psychology framework.

Reduction in the appearance of facial hyperpigmentation after use of moisturizers with a combination of topical niacinamide and N-acetyl glucosamine: results of a randomized, double-blind, vehicle-controlled trial.

BACKGROUND: Topical niacinamide and N-acetyl glucosamine (NAG) each individually inhibit epidermal pigmentation in cell culture. In small clinical studies, niacinamide-containing and NAG-containing formulations reduced the appearance of hyperpigmentation. OBJECTIVES: To assess the effect of a combination of niacinamide and NAG in a topical moisturizing formulation on irregular facial pigmentation, including specific detection of changes in colour features associated with melanin. METHODS: This was a 10-week, double-blind, vehicle-controlled, full-face, parallel-group clinical study conducted in women aged 40-60 years. After a 2-week washout period, subjects used a daily regimen of either a morning sun protection factor (SPF) 15 sunscreen moisturizing lotion and evening moisturizing cream each containing 4% niacinamide + 2% NAG (test formulation; n = 101) or the SPF 15 lotion and cream vehicles (vehicle control; n = 101). Product-induced changes in apparent pigmentation were assessed by capturing digital photographic images of the women after 0, 4, 6 and 8 weeks of product use and evaluating the images by algorithm-based computer image analysis for coloured spot area fraction, by expert visual grading, and by chromophore-specific image analysis based on noncontact SIAscopy for melanin spot area fraction and melanin chromophore evenness. RESULTS: By all four measures, the niacinamide + NAG formulation regimen was significantly (P < 0.05) more effective than the vehicle control formulation regimen in reducing the detectable area of facial spots and the appearance of pigmentation. CONCLUSIONS: A formulation containing the combination of niacinamide + NAG reduced the appearance of irregular pigmentation including hypermelaninization, providing an effect beyond that achieved with SPF 15 sunscreen.