Maintenance effect of a once-weekly regimen of a Selenium Disulfide-based shampoo in moderate-to-severe scalp seborrheic dermatitis after initial treatment with topical corticosteroid/salicylic acid.

INTRODUCTION: Seborrheic dermatitis (SD) is a chronic, relapsing, inflammatory disorder of the head and trunk. OBJECTIVES: To explore the potential of a 1% Selenium disulphide (SeS2)-based shampoo to prevent relapses of scalp SD (SSD) following corticosteroid/salicylic acid (TCS/SA) treatment. MATERIALS & METHODS: After a 2-week treatment with TCS/SA, adult patients with moderate-to-severe SSD received either the SeS2-based shampoo or its vehicle for eight weeks in a randomized, double-blinded fashion. Visits took place at baseline, weeks 2, 6 and 10. SSD severity was assessed based on erythema, flakes and pruritus; patients assessed the severity of pruritus. Global investigator and patient satisfaction were assessed at week 10. RESULTS: Forty-eight adults were included. After four and eight weeks of post TCS/SA maintenance regimen, 8.1% and 16.7% in the SeS2, and 41.7% and 54.2% in the vehicle group relapsed, respectively. First median time-to-relapse in the vehicle group was 56 days; this was not reached for SeS2. After two weeks of TCS/SA, the prevalence of patients with no pruritus was 29.2% in the SeS2 group, and 41.7% in the vehicle group; it increased to 76.2% with SeS2 and to 57.1% with the vehicle at the end of the study. The clinical benefit of treatment with TCS/SCA was maintained in the SeS2 group only. Investigators and patients were highly satisfied with the efficacy of SeS2. Tolerance to SeS2 was excellent, with no reported adverse events. CONCLUSION: The SeS2-based shampoo significantly reduces the time-to-relapse of moderate-to-severe SSD flares. Its tolerance was excellent, with no reported adverse events.

Selenium disulfide: a key ingredient to rebalance the scalp microbiome and sebum quality in the management of dandruff.

BACKGROUND: Dandruff is a chronic and relapsing scalp condition characterized by flaky scalp. Environmental and host factors (exposome) may alter the sebaceous gland activity, sebum composition, epidermal barrier function, and scalp microbiome balance, resulting in dandruff. Selenium disulfide (SeS2) improves the clinical signs of dandruff. OBJECTIVES: To investigate the mode of action of SeS2 shampoo during treatment and relapse phases. MATERIALS & METHODS: Two single-center studies assessed dandruff severity, subjective efficacy perception, microbial balance, microbiota diversity and sebum lipids. RESULTS: SeS2 significantly (p≤0.01) reduced scaling and led to a significant decrease of Malassezia and Staphylococcus spp. counts in both lesional and non-lesional areas, compared to the vehicle at D28 returning to baseline levels at D56. Cutibacterium spp. levels were not different between the SeS2 and the vehicle treatment groups but had significantly increased with SeS2 (p<0.001) in the lesional zone at D56. The ratio Malassezia spp./Cutibacterium spp. decreased significantly in lesional zones compared to baseline levels, at both D28 and D35 (p<0.001). The total squalene content significantly increased (p<0.05), whereas peroxided squalene had significantly decreased by almost 50% at D31. The ratio triglycerides/free fatty acids significantly (p<0.0001) increased, almost 5-fold, between D0 and D31. SeS2 shampoo was very well tolerated. CONCLUSION: SeS2 is beneficial in scalp dandruff, even after treatment interruption. It is well tolerated, rebalances the equilibrium between the main bacterial and fungal populations, and improves sebum quality.

Exploring some characteristics (density, anagen ratio, growth rate) of human body hairs. Variations with skin sites, gender and ethnics.

OBJECTIVE: To determine, in vivo, the density, growth rate and percentage of anagen phase follicles of body hairs present on five different skin sites (axilla, cheek, chin, leg, upper-lip) of women and men from four different ethnics (African, Caucasian, Chinese, North African). The same characteristics of terminal hairs from the nape of all subjects were recorded as references. METHODS: The photo-trichogram technique was used on all skin sites (of different sizes) at variable times (2 or 3 days) post shaving of small skin areas (a few cm2 ). Digital photographs were then analysed through a dedicated software that allows to record the density of body hairs (N cm-2 ), the % of growing hairs (Anagen phase) and their growth rates (in µm day-1 ). RESULTS: The densities of terminal hairs (on nape) found on all subjects were similar to those previously observed on much larger populations. The same ranking of a decreased density of body hairs in the five skin sites was observed in men, irrespective with ethnics. Body hairs seem homogeneously distributed among ethnics on armpit and leg with slight gender-related differences. In men, a significantly higher anagen phase percentage (> 85%) is found on terminal hairs, cheek and upper-lip region in Caucasians and North Africans, as compared to African and Chinese men. The technique used cannot precisely determine the very thin hairs present on the faces of all women. The anagen phase percentage appears higher in all women on leg and armpit. Hair body growth rates ranged from 180 to 485 µm day-1 and were found, on axilla, close to those of terminal hairs. CONCLUSION: The abundance of body hairs, in the studied skin sites, appears similar, irrespective with ethnic groups, whereas their functional characteristics (anagen ratio, growth rate) are more driven by individual/gender influences. RÉSUMÉ: Objectif Déterminer, in vivo, la densité, la vitesse de pousse et le pourcentage de follicules en phase anagènes des poils corporels présents sur 5 sites cutanés différents (l'aisselle, la joue, le menton, la jambe, la lèvre supérieure) de femmes et d'hommes issus de 4 groupes ethniques différents (Africain, Caucasien, Chinois, Nord-africain). Ces mêmes caractéristiques ont été enregistrées pour les cheveux (poils terminaux) en nuque de tous les sujets en tant que références. Méthodes la technique du photo-trichogramme a été utilisée sur tous les sites cutanés (de tailles différentes) après un temps variable (2 ou 3 jours) suivant le rasage de petites zones cutanées (quelques cm-2 ). Les photographies numériques ont été alors analysées par un logiciel spécifique qui permet d'enregistrer la densité de poils corporels (N.cm-2 ), le pourcentage de poils en phase de croissance (la phase Anagène) et leur vitesse de pousse (en µm/jour). Résultats la densité de cheveux (en nuque) trouvée sur tous les sujets était semblable à celle précédemment observée sur des populations beaucoup plus larges. On retrouve chez les hommes le même classement entre les 5 sites cutanés en termes de densité de poils corporels, indépendamment du groupe ethnique étudié. Les poils corporels semblent distribués de manière homogène parmi les membres d'un groupe ethnique sur l'aisselle et la jambe avec des légères différences liées au genre. Chez les hommes, les Caucasiens et les Nord-Africains présentent un pourcentage de poils terminaux en phase anagène significativement plus élevé (>85%) sur la joue et la région de la lèvre supérieure que les hommes Africains et Chinois. La technique utilisée ne permet pas précisément de déterminer la présence de poils très minces sur les visages des femmes. Le pourcentage de poils en phase anagène paraît plus élevé chez les femmes sur la jambe et l'aisselle. Les vitesses de pousse des poils corporels s'étendent de 180 à 485 µm/jours et se trouvent, sur les aisselles, proches de celles des cheveux. Conclusion la densité de poils corporels, dans les sites cutanés étudiés, présente une variabilité de sites indépendante du groupe ethnique considéré, tandis que leurs caractéristiques fonctionnelles (le ratio de poils en phase anagène, la vitesse de pousse) sont plus dirigées par des influences d'individu/genre.

Diversity in human hair growth, diameter, colour and shape. An in vivo study on young adults from 24 different ethnic groups observed in the five continents.

Based on previous findings, from a worldwide study, classified the shapes of human hair into 8 major types, from straight to highly curly. This clearly extended the usual classification of hair into African, Asian or Caucasian types. However, determinations of hair growth parameters and hair density were excluded from such studies. To measure and compare the hair growth profiles of young adults without alopecia living in the five continents. 2249 young adults (18-35 years, females and males) without alopecia, originating from 24 various human ethnic groups were included in the study. Total hair density, telogen percentage and growth rate on three different scalp areas were measured, using non-invasive validated techniques. Natural hair colour level, curliness and hair diameter were additionally recorded, when practically possible. Diversity in hair growth parameters among the entire cohort was a key finding, with differences linked to scalp area, gender and geographic origin. Statistical approaches depicted African hair as having lower density and a slower growth rate. Asian hair showed a thicker diameter, with faster growth. Caucasian hair showed a high total hair density. On the one hand, this inter-continental study of hair growth parameters provides initial valuable base-line data on hair in young adults without alopecia, and on the other hand, further extends our knowledge of this unique human appendage, with some mosaic features, observed worldwide.

Functional and structural age-related changes in the scalp skin of Caucasian women.

BACKGROUND: Ageing of the skin, being chronological or sun induced is highly documented. Scalp, as a specific skin site, has, however, received little attention. This work attempted to describe functional and structural alterations that occur in scalp skin with ageing. METHODS: Two different age groups (N = 15 each; 30 ± 3 and 62 ± 2 y.o. respectively) of Caucasian women participated in the study. Some functional parameters (TEWL, Sebum level, Hydration, T°) were recorded on the vertex part of the scalp, after having cut the hair flat on the scalp surface. Imaging of some structural criteria was carried out using high-frequency ultrasound technique and optical coherence tomography on the same scalp site and on the mid-forehead, as a close control skin site. RESULTS: As compared with the younger group, the scalp of older women significantly showed a decreased TEWL and a slightly lower T°. The thickness of total skin (epidermis + dermis) increased with age on both scalp and on forehead. The thickness of scalp epidermis decreased with age while not significantly altered on forehead. Pseudoattenuation of ultrasound images increased in the older age group. Other criteria, such as sebum level, stratum corneum hydration, stratum corneum thickness, were not found altered with age. CONCLUSION: With ageing, some few functional and structural changes are observed in the scalp of Caucasian women. Similarities or differences with those previously reported in other skin sites are discussed.

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.

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.

Skin capacitance imaging and corneosurfametry. A comparative assessment of the impact of surfactants on stratum corneum.

Silicon image sensor (SIS) technology was recently introduced as an innovative tool (SkinChip, L'Oréal) providing sensitive imaging of the skin capacitance. This method can detect discrete focal variations in skin surface hydration, and thus early discrete manifestations of skin irritation induced by surfactants. In the present in vivo study, 2 neat and diluted shampoos, and 5% and 10% sodium laurylsulfate solutions were tested on human skin. Each surfactant solution was gently rubbed on the skin using wet hair wicks mimicking the casual use of a shampoo on the scalp. Clinical and SIS evaluations were carried out. In addition, the same products were tested using the ex vivo corneosurfametry bioassay performed on human stratum corneum (SC) harvested by cyanoacrylate skin surface strippings. The colourimetric index of mildness (CIM) was measured on these samples. The product reactivity with the SC was recognized by darker skin capacitance images, and by both lowered SkinChip-generated values and lowered CIM values. The extent in changes varied according to the nature of the test products and their concentrations. The SkinChip image changes likely corresponded to the acute surfactant-induced water swelling of the corneocytes. Skin capacitance imaging and corneosurfametry allow to disclose discrete surfactant-induced alterations of corneocytes.

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.