Age-dependent changes in eumelanin composition in hairs of various ethnic origins / S. Commo in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 34, N° 1 (02/2012)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 34, N° 1 (02/2012) . - p. 102-107 Titre : Age-dependent changes in eumelanin composition in hairs of various ethnic origins Type de document : texte imprimé Auteurs : S. Commo, Auteur ; K. Wakamatsu, Auteur ; Isabelle Lozano, Auteur ; S. Panhard, Auteur ; G. Loussouarn, Auteur ; B. A. Bernard, Auteur ; S. Ito, Auteur Année de publication : 2012 Article en page(s) : p. 102-107 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cheveux Dopachrome Tautomerase Eumélanine Mélanine Tags : Âge  'Dopachrome  tautomerase'  'Origine  ethnique'  Eumélanine  'Mélanine  cheveu' Index. décimale : 668.5 Parfums et cosmétiques Résumé : Hair pigmentation is one of the most conspicuous phenotypes of humans. From a chemical point of view, however, data remain scarce regarding human hair pigmentation characteristics. To determine melanin content and composition in human eumelanic hair from individuals of different ethnic origins and at different ages, we collected hair from 56 subjects with eumelanic hair from each group of African-American, East Asian, and Caucasian origin. The 56 subjects consist of 14, seven each of males and females, each from four age classes of younger than 11, between 12 and 19, between 20 and 45, and older than 46. We analysed hair colour scale, total melanin value, and contents of pyrrole-2,3,5-tricarboxylic acid (PTCA) and pyrrole-2,3-dicarboxylic acid (PDCA). We measured age-dependent increases in the relative quantity of eumelanin in pigmented human hairs in the three ethnic groups. Regarding melanin composition, we observed an increase in the PDCA/PTCA ratio with age in African-American and Caucasian hairs until approaching the quite constant level of the ratio in East Asian hairs in the elderly individuals. Our results evidence differences in the content and composition of eumelanin in human hair among African-American, Caucasian and East Asian individuals. Furthermore, we show evidence of age-dependent changes in the quantity and quality of eumelanin in pigmented human hairs. In particular, the age-dependent modification of the PDCA/PTCA ratio, a marker for 5,6-dihydroxyindole units in eumelanin, suggests a chronological evolution of hair follicle melanocyte phenotype (e.g. decrease in dopachrome tautomerase expression). Note de contenu : - MATERIALS AND METHODS : Hair samples - Chemical analyses - Statistical analyses - RESULTS : Pigmentation scores in the three ethnic groups - Effect of age on quantity and quality of eumalenin DOI : 10.1111/j.1468-2494.2011.00691.x En ligne : http://onlinelibrary.wiley.com/doi/10.1111/j.1468-2494.2011.00691.x Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=13285 [article]

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The diversity of the human hair colour assessed by visual scales and instrumental measurements. A worldwide survey / Isabelle Lozano in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 39, N° 1 (02/2017)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 39, N° 1 (02/2017) . - p. 101-107 Titre : The diversity of the human hair colour assessed by visual scales and instrumental measurements. A worldwide survey Type de document : texte imprimé Auteurs : Isabelle Lozano, Auteur ; J. B. Saunier, Auteur ; S. Panhard, Auteur ; G. Loussouarn, Auteur Année de publication : 2017 Article en page(s) : p. 101-107 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse spectrale Cheveux -- analyse Colorimétrie Pigmentation des cheveux Index. décimale : 668.5 Parfums et cosmétiques Résumé : Objectives : To study (i) the diversity of the natural colour of the human hair through both visual assessment of hair tone levels and colorimetric measurements of hair strands collected from 2057 human male and female volunteers, from 23 regions of the world and (ii) the correlation between visual assessments and colorimetric measurements. Methods : Hair strands were analysed by a spectrocolorimeter under the L*, a*, b* referential system and scored in vivo by experts before sampling, through standardized visual reference scales based on a 1–10 range. Results : Results show that from a typological aspect, black or dark brown hairs largely predominate among studied ethnic groups, whereas Caucasian or derived populations exhibit the widest palette of medium to fair shades, partly explaining some past interbreeding among populations. Instrumental measurements clearly confirm that a given colour of a pigmented hair, at the exclusion of red hairs, is mostly governed by two components, L* and b*, from the L*, a*, b* reference system. Conclusion : The comparisons between visual assessments and instrumental data show that these appear closely linked. Darker hairs show close or subtle variations in L*, a*, b* parameters, making their individual colour differentiation calling for technical improvements in colorimetric measurements. The latter are likely governed by other physical factors such as shape, diameter and shine. Note de contenu : - MATERIALS AND METHODS : Subjects - Hair sampling - Visual assessments - Colorimetric measurements - Statistics - RESULTS : Overall analysis through L*, a*, b* axis - Pigmented hairs (non-red, non-white) - Links between instrumental measurements and visual assessments - Pigmented hairs and geographical regions - The case of red hairs - The case of grey hairs DOI : 10.1111/ics.12359 En ligne : https://drive.google.com/file/d/14reAZ0LwAy-UVulJwPj_a2YASTVOECxx/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=27849 [article]

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