Morphometric characteristics of feminine eyebrows: variations with ethnicities and age.

OBJECTIVE: To explore some morphological features of the eyebrows of women of different ethnicities and ages. MATERIALS AND METHODS: Standard digital photographs of 3600 women of six ethnicities, aged 18-84 years, previously used to describe the morphology of the human eyes, allowed us to focus on their eyebrows, as supplementary and opportunistic study. Photographs of both eyebrows were analysed partly by manual markings and automatically by dedicated algorithms. Six parameters of the eyebrows were recorded: length, waviness/curvature, oblique aspect, size (vertical height), total surface and hair coverage (density). RESULTS: Most criteria present ethnic specificities. These are: length (longer eyebrows of Indian, shorter among African women); waviness where the straighter eyebrows were found among Chinese and Japanese women. In general, the longer the eyebrows, the higher their waviness and vice versa. Thickness (or height) of the eyebrows presents a wide ethnic variability as well as hair coverage, where African women present the lower hair density, inversely to Indian women. The same holds true with regard to the total surface of eyebrows, of a large variability (by about four times). Some criteria appear more individually dependent than ethnic-specific, such as the oblique positioning, at the exception of Indian women with less oblique eyebrows. In all subjects, the criteria of both eyebrows (Left vs. Right) were found to be highly correlated (r > 0.7, P < 0.001). CONCLUSION: The present investigation brings new findings on a scarcely studied facial element, the morphologic features of which are, for most, ethnic-dependent. As applied consequences, the results of the present work pave the road to better adapt adorning procedures of the eyebrows vis-à-vis ethnic and age specificities.

OBJECTIF: D'explorer quelques critères morphologiques des sourcils de femmes de 6 ethnies, d'âges différents (18-84 ans). MÉTHODES: Des photographies digitales standards de 3600 femmes de 6 ethnies, âgées de 18 à 84 ans, préalablement utilisées pour décrire les morphologies des yeux, ont été mises à profit pour une analyse morphologique dédiée aux sourcils. Les images ont été analysées pour partie par marquages manuels, pour partie par des algorithmes de reconnaissance automatique. Six critères ont été analysés: longueur, ondulation, aspect oblique, taille (hauteur), surface totale et couverture pilaire (densité des poils). RÉSULTATS: Chez tous les sujets, les critères des deux sourcils (Gauche et Droit) ont été observés comme fortement corrélés, et présentent des spécificités ethniques pour la plupart. Par exemple, la longueur, i.e. plus élevée chez les femmes Indiennes, plus faibles chez les femmes Africaines, l'ondulation où les sourcils les plus droits sont trouvées chez les femmes Chinoises et Japonaises. En général, les plus longs sourcils présentent une plus forte ondulation et vice versa. Leur hauteur maximale présente aussi une forte dépendance ethnique tout comme la couverture pilaire où les femmes Africaines montrent une plus faible densité, à l'inverse des femmes Indiennes. Un même résultat est obtenu pour la surface totale qui présente de fortes variations inter-ethniques, allant du simple au quadruple. D'autres paramètres semblent plus individuels qu'ethniques tel que l'aspect oblique, à l'exception des femmes Indiennes qui présentent les sourcils les moins obliques. CONCLUSION: Cette investigation apporte quelques nouveaux résultats sur un sujet très peu étudié, dont la morphologie est, sur de nombreux aspects, ethnique-dépendante. Ces résultats offrent alors, en terme d'application, une approche plus adaptée des procédures d'ornementation des sourcils vis à vis des spécificités ethniques et de l'âge.

The worldwide diversity of scalp seborrhoea, as daily experienced by seven human ethnic groups.

OBJECTIVE: The re-greasing process and kinetics of the human scalp, post-shampooing, have been previously documented, in vivo, on a few Caucasian subjects. The objective of the presented research was to extend such knowledge over seven different ethnic groups. METHODS: The post-shampooing re-greasing kinetics of the scalp was studied on 1325 subjects (women and men of two distinct age classes) from seven different ethnic groups in their residential and native country. Sebum amounts were determined onto small shaved scalp areas at various times post-shampooing, using the Sebumeter® technique. RESULTS: As previously published on Caucasian subjects, scalp re-greasing process follows a hyperbolic-like kinetics over days. However, amounts of collected sebum highly vary with ethnicity. As recorded through the casual level (CL) at the equilibrium phase, 2-3 days post-shampooing, the highest amount of sebum was found in African American subjects, followed in descending order by Caucasian American, Japanese, Chinese, Thai, Caucasian European and Indian subjects, the latter showing very low values. Lower amounts of sebum were recorded in the older age class in all ethnics, as compared to the younger one, and male subjects were found higher sebum producers than women, irrespective of ethnicity. CONCLUSION: The kinetics and slopes of the re-greasing process of the human scalp appear similar in all ethnic groups studied. However, striking quantitative differences are found between the seven ethnic groups, resulting from different sebaceous production levels and scalp hygiene routines.

The colour of the human skin: fruitful science, unsuitable wordings.

A review of the various facets of the colour of human skin is proposed. It aims first at illustrating the paradoxical association of the remarkable recent scientific advances that characterize changes in the skin colour, with some totally inappropriate or outdated phrasings used in its communication. As a second objective, it aims at proposing an alternative to these wordings. The latter would combine six shade types, defined by Individual Type Angle (ITA) values, a coloured reference chart and associated colour adjectives, highly corresponding to the six Phototypes previously defined by Fitzpatrick. Such alternative would overcome most references to both ethnic- and ethical-related issues.

[Place your bets, the die is cast ... the skin at the retiring age today and tomorrow]. / Faites vos jeux, rien ne va plus ... la peau à l'age de la retraite, aujourd'hui et demain.

Senescence of people represents a global expression of obsolescence of their organs, tissues, cells and constitutive molecules. Skin, similarly to any other organ, is ageing in particular ways. Over the past century, the time effects on skin have been expressed differently. Skin of any individual presently engaged in the Third Age looks different from that of his/her line ancestral. What is the expected future? The Third Age population is expanding and skin problems call for a variety of management procedures. Prevention of the diverse types of skin ageing has made tremendous progresses particularly in the field of preventive and corrective dermocosmetology. The future should further speed up such trends.

[Striae distensae, colors and mechanobiology]. / Les vergetures, leurs couleurs et leur mécanobiologie.

Striae distensae represent a common skin condition, corresponding to a physiological event particularly developed during adolescence, pregnancy and gain in body weight. In addition, these lesions are induced by the Cushing syndrome or an intense corticotherapy. The viscoelastic properties of the skin are altered and vary according to the severity of striae distensae. Otherwise, the colours of striae distensae vary with time in response to the mechanobiology of blood vessels and melanocytes.

A preliminary investigation of the impact of oily skin on quality of life and concordance of self-perceived skin oiliness and skin surface lipids (sebum).

OBJECTIVE: This preliminary study investigated both the impact of oily skin on quality of life (QoL) and the agreement between subjective oily skin self-assessment and objective skin surface sebum measurement in young to middle-aged Chinese women in Beijing. METHODS: A 18-item Chinese version of the Oily Skin Self-Image Questionnaire (OSSIQ) was used to assess the impact of oily skin on QoL in 300 healthy female subjects (age groups: 20-25; 26-30; 31-35,). The subjects were divided equally into the oily skin group and the non-oily skin group based on their self-perception of skin oiliness. The level of skin surface lipids (SSL) was measured on the middle of the forehead, and both cheeks using the Sebumeter(®). In order to assess the agreement between self-perceived skin oiliness and measured SSL, we tentatively used the SSL median value as a dividing point to regroup all subjects. RESULTS: The results indicate that the Chinese version of the OSSIQ distinguished the oily skin group from the non-oily skin group. Subjects in the oily skin group had significant higher emotional status score and behavior score when compared with subjects in the non-oily skin group. Subjects in the oily skin group had higher SSL when compared with subjects in the non-oily skin group, especially in younger age groups. The agreement between self-perceived skin oiliness and measured SSL was moderately strong in younger age groups, and declined with age. CONCLUSION: These results strongly suggest that having oily skin can cause a significant negative impact on QoL among Chinese women. The Chinese version of the OSSIQ is a reliable and valid tool for assessing the impact of oily skin on QoL. The accuracy of oily skin self-assessment declines with age.

'Cosmeceuticals'. Of men, science and laws .

Through the hybrid term 'Cosmeceuticals', the present paper aims at reviewing some scientific and legal sources of ambiguities or uncertainties that, in many regulatory cases, added confusions to the respective roles of drugs and cosmetics. The origins of such questions, likely arose from new anti-ageing claims from the cosmetic industry in the late 80s which faced a rather old regulatory backdrop. Based on the analysis of some legal statements and scientific facts from a 2012 vision, this review tentatively aims at re-defining the respective roles of these two branches that both fill the two vital needs of humans, 'being' and 'well-being'.

Relationships between hair growth rate and morphological parameters of human straight hair: a same law above ethnical origins?

After measurement of individual growth rates, natural hair fibres from Asian and Caucasian subjects were analysed using scanning electron microscopy. In total, more than 1000 hairs were analysed. Measurements of diameter, medulla and interscale distance (average distance between two successive cuticle scales) show these parameters strongly correlated with hair growth rate. A thicker hair fibre corresponds to a faster growth rate, a shorter interscale distance and greater probability to have a medulla, and vice versa, a thin hair fibre shows slower growth rate, a larger interscale distance and a lower probability to have a medulla. Very interestingly, this finding appears to be unrelated to the ethnic origin of the subjects, suggesting a common characteristic of human hair, at least for the straight or semi-straight hair studied. From a practical viewpoint, this finding clearly suggests an alternative method for measuring hair growth rates, by measuring the interscale distance, which appears easier than using common laboratory equipments.

Challenging the scalp with 'dry' wash shampooing (DW) on Chinese men: an in vivo study.

Cosmetic habits show a strong diversity worldwide. The same applies to procedures that are considered as basic hygiene acts such as shampooing. Apart from common traditional shampoo routine, a special shampoo procedure, 'dry' wash is daily performed in Chinese hair salons. Without pre-wetting step, hairdresser applies the shampoo directly to dry hair with small quantity of water to create foam. Hand massaging is then offered on the scalp. This shampooing process is distinguished from traditional 'regular wash' by slightly diluted shampoo, and longer contact with the scalp and scalp massaging, all of which could be possibly considered as challenges to the structure and barrier function of the scalp. In this study, the effects of 'dry' wash on Chinese scalp have been investigated, in vivo, using regular wash as a control. A total of 67 Chinese males in two cohorts, non-dandruff and with dandruff, were included. In each cohort, volunteers were split into two groups, one with 'dry' wash and the other one with regular wash. Both shampoo methods were performed daily for five consecutive days using the same shampoo formulation. Volunteers' self assessment, clinical assessment by an expert and instrumental measurements were carried out. The results showed that Chinese 'dry' wash did not induce any negative consequence on the scalp physiology under such experimental conditions.

Chronological ageing of human hair keratin fibres.

Examination of very long hair (length > 2.4 m) using a large range of evaluation methods including physical, chemical, biochemical and microscopic techniques has enabled to attain a detailed understanding of natural ageing of human hair keratin fibres. Scrutinizing hair that has undergone little or no oxidative aggression--because of the absence of action of chemical agents such as bleaching or dyeing--from the root to the tip shows the deterioration process, which gradually takes place from the outside to the inside of the hair shaft: first, a progressive abrasion of the cuticle, whilst the cortex structure remains unaltered, is evidenced along a length of roughly 1 m onwards together with constant shine, hydrophobicity and friction characteristics. Further along the fibre, a significant damage to cuticle scales occurs, which correlates well with ceramides and 18-Methyl Eicosanoic Acid (18-MEA) decline, and progressive decrease in keratin-associated protein content. Most physical descriptors of mechanical and optical properties decay significantly. This detailed description of natural ageing of human hair fibres by a fine analysis of hair components and physical parameters in relationship with cosmetic characteristics provides a time-dependent 'damage scale' of human hair, which may help in designing new targeted hair care formulations.

[Circadian chronophysiology of the scalp]. / Chronophysiologie circadienne du cuir chevelu.

Biological rhythms are numerous and vary according to periodicity and amplitude. Variations over the course of a day, particularly circadian rhythms have been reported in the skin of the face and forearms. However, little information is available about daily biorhythms of the scalp. The aim of the present study was to explore the chronophysiology of the scalp. We report a series of diurnal rhythms in 8 Caucasian men using the plexogram method at 4-h intervals over a 5-day period. Statistically significant biorhythms were found for the colour, hydration, barrier function and pH of the skin, and for the sebum excretion as well. The early afternoon was the time of maximum increase in redness, hydration, pH and sebum output, combined with decreased skin barrier function. The amplitude of some of these biorhythms was so discrete that their clinical relevance remained uncertain even when they appeared statistically significant. In view of the apparent synchronization between them, it is likely that a central oscillator exerts a major influence. However, only rare subjects exhibited biorhythms for all the considered physiological parameters. Hence, peripheral reactivity and/or environmental synchronizers also play an important role to define the good and bad respondors to the potential biorhythms of each individual parameter.

Dandruff-associated smouldering alopecia: a chronobiological assessment over 5 years.

BACKGROUND: In some individuals, dandruff may be recurrent and even chronic. This represents a difficult-to-treat condition. Excessive hair shedding and diffuse alopecia may develop. OBJECTIVES: To evaluate the chronobiological aspects of dandruff, hair shedding and alopecia. METHODS: This study was performed in eight men suffering from such a scalp condition. They were examined 40 times at regular intervals for five consecutive years. Hair-density assessments and trichograms were performed at least twice per trimester on the parietal region of the scalp, corresponding to an area where dandruff was present. RESULTS: A positive correlation was found between the percentage of telogen hairs and dandruff severity as assessed by the squamometry index. Bimodal yearly biorhythms were found for dandruff severity, telogen counts and hair loss between two consecutive visits. The chronobiological fluctuations were prominent in some study participants, but remained inconspicuous in others. The biorhythms were almost synchronized in all participants, showing variations over the year. CONCLUSIONS: The biorhythms on the hair cycle in dandruff are not fundamentally different from those previously reported in subjects without dandruff. The periodicity may be an intrinsic feature of human skin.

[Normal and pathologic sebaceous function. Research in a shallow milieu?]. / Fonction sébacée normale et pathologique. Des recherches au milieu du gué?

Modern therapeutic approaches allow to control sebaceous secretion but knowledge about the sebaceous gland and its precise function within the pilosebaceous unit is still insufficient. Steroid hormones are the principal albeit not exclusive regulators of the sebaceous glands. Three phases may be distinguished in sebaceous physiology: secretion-production, stocking in the follicular reservoir, and excretion. Human "native" intracellular sebum, before secretion, is composed of squalene, waxes, and triglycerides. Once secreted, the sebum is colonised by various xenobiots whose development is controlled by several defensive humoral mechanisms and by the contact with ambient oxygen. Oxygen and micro-organisms transform "native" sebum, lysis of triglycerides to fatty acids being the most pronounced activity. Certain components of this complex mixture of molecules present in the sebum are clearly cytotoxic or irritant, provoking reactive follicular hyperkeratosis and comedone formation--the first step to acne. Some lipophilic organisms like Malassezia yeast may be highly antigenic and induce chronic inflammatory reactions like in seborrhoeic dermatitis. Demodex is an inrafollicular parasite feeding on sebum that frequently causes blepharitis. Sebum is also a vehicle transporting and transmitting several endogenous and exogenous molecules, including potential regulatory factors of hair follicles. Recent development of in vitro cultures of functional sebocytes should help to better understand several aspects of the sebaceous gland's biology.

Effect of residence time on the efficacy of antidandruff shampoos.

Dandruff is known to be controlled by fungistatic shampoos active against Malassezia spp. These products also remove the loosely attached scales. This study was performed to assess the effect of a 5-min residence time on the efficacy of antidandruff shampoos. Two commercially available shampoos were used in two groups of 21 panelists with severe dandruff. They contained either 1% ketoconazole or 1% piroctone olamine. In each group, intraindividual comparisons were made by a split-scalp design between the effect of a 5-min residence time versus no residence time. Both shampoos induced significant reductions in scaliness and yeast colonization. The beneficial effects were obvious immediately after one single shampooing and 3 days later as well. The improvement was greater with a 5-min residence time. The piroctone olamine treatment benefited more than the ketoconazole treatment from the extension of shampoo-exposure time. In conclusion, the benefit of a residence time in treating dandruff is documented. The level of improvement in efficacy may vary according to the nature of the shampoo.

The hair eclipse phenomenon: sharpening the focus on the hair cycle chronobiology.

Chronobiology governing the hair cycle is a fascinating and complex process. Both the hair growth cycle and the hair shaft growth are coordinated and depend on the interplay of different biological signals and various exogenous stimuli. A latency period may occur between hair shedding (teloptosis, exogen phase) and the early emergence of the next anagen VI stage. This lag time referred to on the hair eclipse phenomenon likely depends on the influence of a series of distinct synchronizers, and does not represent per se a peculiar hair cycle phase. It is the result of some dysregulations of the hair cycling, involving early teloptosis, delayed anagen I initiation or stunted hair growth at any stage between the anagen I and anagen V phases. As such, the hair eclipse phenomenon may be an erratic process occurring in physiopathological conditions affecting hair follicles singly or in focal to generalized patterns. It may be more frequent when it follows synchronized teloptosis occurring in telogen effluvium (newborn alopecia, post-partum alopecia, seasonal alopecia and alopecia areata). It may also be prominent when microinflammation is abutted on the permanent portion of the hair follicle as in dandruff, seborrhoeic dermatitis, androgenic alopecia and photoageing baldness. Local synchronizers such as growth factors and other mediators may eventually be lacking or involved in the hair eclipse phenomenon. Their identification and characterization might drive new corrective or preventive applications.

Isolation and identification of human hair ceramides.

Synopsis The analysis of the lipids extracted from human hair by silica-gel-column liquid chromatography permitted an isolation of the fraction enriched in free ceramides. These were identified by GC/MS and are related to ceramide classes 2 and 5 in which the long-chain base was predominantly sphinganine. This differs from that observed in the free ceramides found within the stratum corenum.

[Physiology of the pilosebaceous follicle]. / Physiologie du follicule pilo-sébacé.

The human pilosebaceous follicle shows an extreme diversity with regard both its variation according to its localisation along the human body, and the various physiological dependences of the two tissues which comprise the pilosebaceous follicle. These latter, highly differentiated toward specialised synthesis (proteins, lipids) have their own specific physiology which, though, responds to some common mediators. Each pilosebaceous follicle shows specific cycles and regulation, irrespective with those of its "neighbour". Despite such a complex situation, the most common features of these two tissues, as well as their endogenous and exogenous consequences, are described.

How does sodium lauryl sulfate alter the skin barrier function in man? A multiparametric approach.

The effects of topically applied sodium lauryl sulfate were studied in vivo, in man, through noninvasive methods and compared with those obtained in vitro, using human stratum corneum as a model. The results show that the very marked increase of transepidermal water loss obtained in vivo cannot be related to any removal of epidermal lipids. The most likely explanation of our findings lies in the hyperhydration of stratum corneum consecutive to the inflammation process and a possible disorganization of the lipid bilayers.

Comparison of the kinetics of sebum secretion in young women with and without acne.

We utilized a sebum-sensitive adhesive film, Sebutape, to visualize the pore patterns of women with and without acne with computerized image analysis. In normal young women, we found a positive correlation between the number of active sebaceous follicles and total sebum excretion. When seborrhea was intense, this correlation was however lost. The situation was more complex in acne. The severity of seborrhea was positively correlated with the mean sebum excretion of individual follicles but not with the number of active follicles.