Photoaging's portrait: The road map towards its photoprotection.

OBJECTIVE: To summarize key research published by the author's group, dealing with skin photoaging and its photoprotection. MATERIALS AND METHODS: Two methodologies (standard photographs and selfies imaging) resulting from referential skin ageing atlases were applied on 2487 subjects of different ancestries, ages and gender. These aimed at first to best assess and grade the variable severities of some facial signs (texture/wrinkles, pigmentary spots, sagging and vascular disorders) that occur progressively during the photoaging process. Second, such methodologies were used to record the benefits brought by a photoprotective regimen (671 women and men). RESULTS: In all studied ancestries, each facial sign show an increase severity along decades, at its own pace, some showing a linear like progression, whereas some plateau at early ages. These changes differed according to skin innate colour (phototype) and with individual behaviours vis-à-vis sun exposures, more so among European women than North-East Asian women. An effect of gender (less severe alterations) was observed on Chinese men, as compared to Chinese women. Pigmentary disorders were found hallmarks of photo-aged North-East Asian women. Globally, photoaging impact the apparent age of the different subjects. The counteracting effects of strong topical Photoprotective regimens were evidenced along a 6-month seasonality in Chinese and French women or 1-year period in Brazilian women with phototypes II to VI. Photoprotection led to a more even skin complexion among Indian subjects with pigment irregularities. CONCLUSION: Two factors clearly hamper a better assessment of the efficiency of photoprotection of the sun-induced cutaneous ageing: short durations (months) of the studies with regard to the global fate of photoaging by decades and the number of studied subjects, limited to hundreds for practical reasons. The methodology based on the automatic analysis of facial signs through selfies images could theoretically bypass both factors, allowing thousands of subjects to be studied along years.

OBJECTIF: Résumer les travaux précédemment publiés par le groupe auquel appartient l'auteur dans le cadre du photo-vieillissement cutané et de sa photoprotection. MATÉRIEL ET MÉTHODES: Deux méthodologies (issues de photographies standards ou d'images selfies) furent successivement utilisées, basées sur des atlas de référence du vieillissement cutané facial, et appliquées à 2487 sujets de différentes ethnies, des deux sexes et d'âges différents. Ces études visaient d'abord à déterminer et quantifier au mieux les sévérités variables de quelques signes du visage (texture/rides, taches pigmentaires, relâchement, désordres vasculaires) qui apparaissent progressivement au cours du photo-vieillissement cutané. En second lieu, de déterminer les bénéfices apportés par un produit photo-protecteur (671 femmes et hommes). RESULTATS: Dans tous les groupes ethniques étudiés, chaque signe du visage possède son développement propre, certains selon une progression quasi linéaire tandis que d'autres atteignent un plateau assez tôt. Ces modifications diffèrent selon la carnation naturelle (phototype) et le carnation individuel vis à vis de l'exposition solaire, surtout chez les femmes Européennes, comparées aux femmes Chinoises. Un effet du genre (modifications moins sévères) a été observé chez les hommes Chinois, comparés aux femmes Chinoises. Les désordres pigmentaires semblent caractériser les femmes asiatiques. Globalement, le photo-vieillissement impacte l'âge apparent des différents sujets étudiés. Les effets luttant contre ces changements, apportés par une forte photoprotection topique ont été mis en évidence après 6 mois chez les femmes Chinoises et Françaises ou sur une période d'un an chez les femmes Brésiliennes de phototypes II à VI. Une forte photoprotection a conduit à une carnation du visage plus homogène chez des sujets Indiens présentant des irrégularités pigmentaires. CONCLUSION: Deux facteurs limitent clairement une meilleure estimation de l'efficacité de la photoprotection du vieillissement cutané photo-induit: courte durée des observations (mois) par rapport au lent (décennies) développement du photo-vieillissement et le nombre de sujets étudiés, limité à quelques centaines pour des raisons pratiques. La méthodologie basée sur l'analyse automatique d'images selfies semble en théorie apte à contourner ces deux facteurs, autorisant l'enregistrement de données sur des milliers de sujets durant des années.

Structural and functional age-related changes in some facial signs of Chinese men: A pilot study.

OBJECTIVE: The objective of the study was to associate, on the same Chinese male subjects, changes in facial ageing signs with some biomechanical skin properties. METHODS: The severities of 20 facial ageing signs of 219 differently aged Chinese men (20-65 years) were graded in blind by trained experts through standardized photographs, using a referential skin Atlas dedicated to Asian men. On each subject, the mechanical properties were assessed on the cheek area (left or right at random) by the validated suction technique Cutometer®. Finally, the skin colour parameters were assessed on images from VISIA-CR device. RESULTS: Clinically speaking, the severity of almost all facial ageing signs increases from 30 to 65 years, in a linear-like progression, whereas the 20-30 years shows weak increases. Skin colour shows slight but progressive decreases in Luminance and ITA, whereas the yellow and red components slightly increased between 40 and 65 years. At the exception of skin firmness, the skin mechanical properties show a clear decline during the 30-50 years period and plateau beyond. CONCLUSION: The present study suggests that the 20-30 years period, albeit more clinically 'silent' than the other periods of age, seems to be an age range during which early alterations of some dermal elements' onset. Deeper in vivo investigating techniques (Echography, Multiphotonic microscopy) are needed to confirm such hypothesis.

OBJECTIF: Pouvoir associer, sur les mêmes sujets masculins chinois, les modifications des signes de vieillissement faciaux avec certaines propriétés mécaniques du tégument. MÉTHODES: Les sévérités de vingt signes du vieillissement faciaux de 219 hommes chinois de différents âges (de 20 à 65 ans) ont été évalués en aveugle par des experts entraînés sur des photographies standardisées en utilisant des échelles cliniques de référence pour les hommes asiatiques issues des Atlas du vieillissement. Sur chaque sujet les propriétés biomécaniques ont été enregistrées sur la zone de la joue (droite ou gauche suivant un plan de randomization) avec un appareil de succion validé, le Cutometer®. Enfin, les paramètres coloriels ont été mesurés sur des images enregistrées avec le VISIA-CR. RÉSULTATS: D'un point de vue clinique, la sévérité de la plupart des signes étudiés augmentent de manière linéaire de 30 à 65 ans, tandis qu'entre 20 et 30 ans les augmentations sont faibles. La couleur de la peau présente une faible, mais linéaire, chute de la luminance et de l'ITA, tandis que les composantes jaune et rouge augmentent légèrement entre 40 et 65 ans. A exception de la fermeté de la peau, les propriétés mécaniques présentent une chute importante entre 30 et 50 ans et un plateau ensuite. CONCLUSION: Cette étude suggère que la période entre 20 et 30 ans, observée comme "silencieuse" d'un point de vue Clinique contrairement aux autres classes d'âge, semble être un moment charnière durant lequel les premières altérations dermiques s'opèrent. De plus amples investigations in vivo usant de techniques d'imageries structurelles (Microscopie Multi-photonique, Echographie…) seraient nécessaires pour confirmer de tells hypothèses.

Age-related changes to characteristics of the human eyes in women from six different ethnicities.

BACKGROUND: To describe some morphological characteristics of the eyes of women of 6 different ethnicities and ages. MATERIAL & METHODS: Standard digital photographs of 3600 women of different ethnicities and ages were taken for evaluating the effects of some makeup products (eyeliners, mascaras, eyelids makeup, etc) through a before/after comparison. Photographs corresponding to pre-applications offered opportunity to quantify, through image analysis, some features of the human eyes (height, length, ellipticity, horizontality, etc) for recording their possible variations linked to ethnicities and/or age. RESULTS: Although some minor differences between ethnicities were found (inter-pupillary distance and inner canthal distance), most eyes criteria among the 11 recorded were comparable (height and length of the eyes, ellipticity, etc). The somewhat low variability of the latter more reflects individual morphologies, at comparable ages. Asian subjects significantly differ by a much more oblique orientation of their main axis versus the horizontal inter-pupillary line. In all ethnicities, the skin aging process was found significantly altering i) the height of the eyes and ii) their orientation. Whereas the decrease of height likely results from a sagging of the upper eyelid, the decrease of orientation in all ethnicities (more marked among Asian women) possibly results from a sagging of the outer corner of the eyes. Whether this sagging may be related to the progressive outcome of crow's feet wrinkles is a plausible hypothesis. CONCLUSION: The present work is an original and complementary approach to the skin aging process prone at modifying some characteristics of women eyes of different ethnicities.

Immunohistochemical patterns in the interfollicular Caucasian scalps: influences of age, gender, and alopecia.

Skin ageing and gender influences on the scalp have been seldom studied. We revisited the changes in the interfollicular scalp. The study was performed on a population of 650 volunteers (300 women and 350 men) for over 7 years. Three age groups were selected in both genders, namely, subjects aged 20-35, 50-60, and 60-70 years. The hair status was further considered according to nonalopecic and alopecic patterns and severity (discrete, moderate, and severe). Biopsies from the parietal area were processed for immunohistochemistry. Stromal cells were distinguished according to the presence of vimentin, Factor XIIIa, CD117, and versican. Blood and lymphatic vessels were highlighted by Ulex europaeus agglutinin-1 and human podoplanin immunoreactivities, respectively. Actinic elastosis was identified by the lysozyme coating of elastic fibres. The epidermis was explored using the CD44 variant 3 and Ki67 immunolabellings. Biplot analyses were performed. Immunohistochemistry revealed a prominent gender effect in young adults. Both Factor XIIIa+ dermal dendrocytes and the microvasculature size decreased with scalp ageing. Alopecia changes mimicked stress-induced premature senescence.

Chemical stability and degradation mechanisms of ferulic acid (F.A) within various cosmetic formulations.

Ferulic acid (F.A) receives significant interest in the beauty industry with regard to its skin-whitening and anti-oxidant properties. However, its use in cosmetics is limited due to pH- and temperature-related instabilities. In this study, we investigated the stability of F.A in eight different prototype formulae. The results confirmed that in our conditions the stability of F.A is pH- and temperature-related. Additionally, the nature of the solvent dipropylene glycol (DPPG) showed a capacity to stabilize F.A. A series of experiments was further planned for studying the mechanism of degradation of F.A. In a prototype of a cosmetic medium, F.A degrades first through a decarboxylation step, leading to 4-hydroxy-3-methoxystyrene (PVG). Further, F.A and PVG are both involved in an additional reaction, resulting in the trans-conjugation dimer of PVG. The consequences of these results in formulating F.A are discussed.

Shape variability and classification of human hair: a worldwide approach.

Human hair has been commonly classified according to three conventional ethnic human subgroups, that is, African, Asian, and European. Such broad classification hardly accounts for the high complexity of human biological diversity, resulting from both multiple and past or recent mixed origins. The research reported here is intended to develop a more factual and scientific approach based on physical features of human hair. The aim of the study is dual: (1) to define hair types according to specific shape criteria through objective and simple measurements taken on hairs from 1442 subjects from 18 different countries and (2) to define such hair types without referring to human ethnicity. The driving principle is simple: Because hair can be found in many different human subgroups, defining a straight or a curly hair should provide a more objective approach than a debatable ethnicity-based classification. The proposed method is simple to use and requires the measurement of only three easily accessible descriptors of hair shape: curve diameter (CD), curl index (i), and number of waves (w). This method leads to a worldwide coherent classification of hair in eight well-defined categories. The new hair categories, as described, should be more appropriate and more reliable than conventional standards in cosmetic and forensic sciences. Furthermore, the classification can be useful for testing whether hair shape diversity follows the continuous geographic and historical pattern suggested for human genetic variation or presents major discontinuities between some large human subdivisions, as claimed by earlier classical anthropology.

Worldwide diversity of hair curliness: a new method of assessment.

BACKGROUND: For many years, cosmetic scientists have attempted to measure the physical features of human hair, such as its shape and colour, as these can be artificially modified using cosmetic products. With regard to hair shape, previous anthropologic studies have emphasized its variability within and between human ethnic groups. Many studies have broadly distinguished three ethnic human subgroups: African, Asian, and Caucasian. Such a broad classification cannot account for the great complexity of human biological diversity, resulting from multiple, past or recent mixed origins. The verbal description of hair shape ranges from the classic to the more sophisticated, with terms such as straight, wavy, curly, frizzy, kinky, woolly, helical, etc. Although these descriptions evoke a global appearance, they remain confusing as their definitions and limits are unclear. Assessments are therefore required to more accurately define such verbal attributes. OBJECTIVE: The work reported here attempts to address the following issues: (i) to define hair types according to specific shape criteria through objective and simple measurements; and (ii) to define such hair types without referring to human ethnicity. METHODS: Measurements of four parameters related to hair curliness (curve diameter, curl index) or kinking of the hair (numbers of waves, numbers of twists) were performed on hair from 2449 subjects from 22 different countries. Principal components analysis and hierarchical ascendant classification were used to identify homogeneous groups of hair and to determine key variables for the assignment of group membership. Finally, a segmentation tree was prepared in order to establish simple rules for predicting group membership of new subjects. RESULTS AND CONCLUSIONS: This study has shown that it is possible to classify the various hair types found worldwide into eight main groups. The approach involves objective descriptors of hair shape, and is more reliable than traditional methods relying on categories such as curly, wavy, and kinky. Applied to worldwide human diversity, it avoids reference to the putative, unclear ethnic origin of subjects. Briefly, a straight hair type I is just that, and whether it originates from a Caucasian or an Asian subject is not at issue. The hair types defined here also more adequately reflect the large variation of hair shape diversity around the world, and may possibly help to trace past mixed origins amongst human subgroups.

The use of hydroxy acids on the skin: characteristics of C8-lipohydroxy acid.

The hydroxy acids are widely used in skin creams because of their exfoliating and rejuvenating effect on photoaged skin. As a member of this family, the salicylic acid derivative known in the literature as 2-hydroxy-5-octanoyl benzoic acid or beta-lipohydroxy acid has also been proposed as an exfoliant and as a treatment of photoaged skin and acne. This article reviews the effects of the hydroxy acids and compares them to those of the salicylic acid derivative. We propose the name C(8)-lipohydroxy acid (C8-LHA) for this derivative to differentiate it from other related compounds. The lipophilic nature of C8-LHA and its relatively slow penetration in the skin afford it an exfoliating effect that is efficient at low concentrations. It appears to have antimicrobial, anti-inflammatory, and anticomedogenic properties, which make it effective against acne. Its antifungal and exfoliating properties are also likely to prove useful in combating dandruff.

Subclinical speckled perifollicular melanosis of the scalp.

Based on the clinical presentation of some skin pigmentation disorders it is thought that a bicompartmental functional system exists in the epidermal melanocyte population. It corresponds to the perifollicular and interfollicular compartments, respectively. The present study was undertaken looking for the presence of such a system on scalp unaffected by pigmentary disorders. The scalps of 100 men with incipient to severe androgenic alopecia were examined using a videocamera equipped with an internal ultraviolet light-emitting unit. The face, trunk and limbs were similarly examined in 45 of these adults and in 13 children of both sexes. In 92 men, a subclinical hypermelanosis was found as a speckled pattern centered on every single follicle. With increasing baldness severity, another epidermal hyperpigmentation pattern involving the interfollicular area was superimposed to the perifollicular pattern. These stereotyped patterns of subclinical melanoderma were also disclosed on the face of adults, but not in children. In addition, the spotty perifollicular pattern was discrete or not apparent on the other parts of the body. It is concluded that the perifollicular subclinical melanotic pattern is a regional characteristic of cephalic skin, perhaps related to the local production of melanocortins, particularly alpha-MSH by the pilosebaceous unit.