Weekly hair washing: The recommended solution for women with afro-textured hair to alleviate dandruff and scalp discomfort.

Dandruff and scalp discomfort are common concerns for women and men in Africa. Moreover, women with afro-textured hair are prone to scalp discomfort owing to irregular hair washing, frequent use of oil-based products on their scalp, and harsh chemical treatments. Current literature does not, however, provide data on the pathophysiological mechanisms of these conditions in this population. In this study, we investigated the mechanisms behind scalp discomfort and dandruff in women of African descent before and after hair washing. We conducted the in Durban, South Africa, over a 3-week period with 60 women of African descent aged 20-40 years. The respondents were equally divided into a "dandruff" and a "no dandruff" group, based on clinical grading of adherent dandruff by a dermatologist. Malassezia spp. and bacterial loads were quantified by quantitative polymerase chain reaction. Evaluations of scalp condition and sample collection were performed at five time points during the 3 weeks. Data on discomfort symptoms were collected via a self-assessment questionnaire. We observed that the dandruff severity peaked at the end of the first week after hair washing and plateaued from thereon in both groups. Dandruff was associated with higher Malassezia and bacterial load counts and there was a direct correlation between the Malassezia spp. load and dandruff score. Via self-assessment questionnaire responses submitted by participants, we observed that itching was the most pronounced scalp discomfort, compared with the sensation of tingling and burning at baseline, while an improvement of the scalp symptoms of dandruff and itch was observed in both groups after one hair wash. The study also showed that higher colonization with Malassezia spp. and bacteria is associated with dandruff independently of the time point, confirming a scalp microbiome contribution to the dandruff pathophysiology in the study population. The benefits of washing were, however, not sustained after 1 week and we thus recommend weekly hair washing for long-term management of dandruff and scalp itchiness in this population.

The Eumelanin Human Skin Colour Scale: a proof-of-concept study.

BACKGROUND: At present there is no standard nomenclature for describing the diversity of human constitutive skin colour. OBJECTIVES: To develop a standard nomenclature to describe human constitutive skin colour. METHODS: Monthly focus group discussions were carried out among a multidisciplinary group of specialists over a 7-month period. Topics covered were (i) limitations and unmet needs of current nomenclature(s) pertaining to human cutaneous diversity, (ii) practical considerations about the function and role of any proposed nomenclature pertaining to human cutaneous diversity, (iii) review of the cellular basis and current molecular genetic understanding of variation in human skin pigmentation and (iv) in vivo methods to evaluate human skin pigmentation. In addition, a preliminary review of the published literature was undertaken to collate data on published skin reflectance measurements, notably melanin index values for well-referenced human populations. RESULTS: We developed a five-point scale to describe the full spectrum of human constitutive skin colour, termed the Eumelanin Human Skin Colour Scale. The nomenclature of the scale uses eumelanin, the dominant chromophore of human skin, as a central descriptive word. The categories of the scale (nomenclature and melanin index values) are eumelanin low (EML), < 25; eumelanin intermediate low (EMIL), 25 to < 50; eumelanin intermediate (EMI), 50 to < 75; eumelanin intermediate high (EMIH), 75 to < 100; and eumelanin high (EH), ≥ 100. CONCLUSIONS: The Eumelanin Human Skin Colour Scale enables the complete range of human constitutive skin colour to be described in an objective, equitable and understandable manner. In future, this scale can be used as the basis for developing other scales that address the specific functional aspects of human skin, such as response to ultraviolet radiation.

Sun Exposure and Black Skin.

Black skin, compared with white skin, is generally assumed to be more resistant to the consequences of sun exposure due to its epidermal melanin content. However, recent scientific evidence shows that black skin is not completely impervious to sunlight. Both clinical and -experimental data have reported sun-induced effects on black skin. Black skin can warm, burn and peel when -exposed to the sun. Exposure to the sun can also cause hyperpigmentation and photoageing manifestations. The current misconceptions expressed by most black individuals about their resistance to sun-induced effects prevent their engagement in sun safe behaviours. Therefore, the demystification of the harmful effects of the sun needs to be supported by more research studies showing the effectiveness of sun protection strategies for the black population.

Quantifying the impact of braiding and combing on the integrity of natural African hair.

BACKGROUND: Afro hair breakage is most commonly attributed to grooming practices such as braiding, hair extensions and weaves, both for chemically treated hair and natural Afro hair. These grooming practices are also frequently associated with traction alopecia in clinical studies. However, there is little to no quantitative scientific data on the surface and internal hair fibre damage caused by grooming, including combing, on Afro hair. METHODS: Qualitative and quantitative techniques such as scanning electron microscopy, cuticle cohesion and tensile testing were used to determine the effects of frequent braiding on the integrity of female Afro hair in 15 frequent braiders and 15 occasional braiders (control group) in Johannesburg, South Africa. Frequent braiders were women who braided more than 8 times per year, while occasional braiders typically limit braiding to only twice 2 per year. The severity of traction alopecia was quantified in both groups using the standard Marginal Traction Alopecia Scoring system. Surface damage on naturally curly Afro hair, that was combed but not braided, was assessed as another hairstyle option. RESULTS: All measurements showed a relationship between surface and internal hair fibre damage and braiding frequency. Frequent braiders had thinner hair, with more cuticle damage as shown by SEM and cuticle cohesion assessments. Their hair fibres were also significantly weaker (p < 0.05), as shown by the tensile testing. In addition, they also had higher traction alopecia severity scores. In the combing impact assessment, a linear trend was observed between surface hair fibre damage and the number of combing strokes. Cuticle damage from 480 combing strokes was more severe than that from frequent braiding. CONCLUSION: Frequent braiding and combing damage natural Afro hair. Quantification of damage caused by different grooming practices identifies a need to develop products that could help mitigate specific hair damage associated with grooming practices. The degree of damage and subsequent hair loss could also be minimized by education on best braiding practices to protect the hair fibre and avoid hair follicle miniaturization caused by high traction hairstyles.

CONTEXTE: La casse des cheveux d'origine Africaine est le plus souvent associées à des pratiques cosmétiques telles que le tressage et les extensions de cheveux, à la fois pour les cheveux traités chimiquement et les cheveux naturels. Ces pratiques cosmétiques sont également fréquemment associées à une alopécie de traction, comme le relatent les études cliniques. Cependant, il existe peu ou pas de données scientifiques quantitatives sur l'impact de ce type de pratiques, y compris le peignage, sur les dommages internes et de surface des cheveux d'origine africaine. MÉTHODES: Des techniques qualitatives et quantitatives, comme la microscopie électronique à balayage (MEB), la cohésion cuticulaire et des tests de traction, ont été utilisés pour déterminer les effets du tressage sur l'intégrité des cheveux de deux groupes de 15 femmes Africaines (à Johannesburg, Afrique du Sud) : un premier groupe de femmes pratiquant un tressage fréquent et un autre groupe un tressage occasionnel. Le groupe des tresseurs fréquents correspond à des femmes qui pratiquent le tressage plus de 8 fois par an, tandis que les tresseurs occasionnels limitent généralement le tressage à seulement deux fois par an. La gravité de l'alopécie de traction a été également quantifiée dans les deux groupes à l'aide du système standard de notation de l'alopécie tractionnelle. Parallèlement, à titre de comparaison, les dommages de surface ont été également évalués sur des cheveux d'origine Africaine naturellement bouclés, non tressés, mais qui ont subi un peignage répété. RÉSULTATS: Toutes les mesures ont montré une relation entre les dommages de surface et internes de la fibre et la fréquence de tressage. Les tresseurs fréquents ont des cheveux plus fins, avec un endommagement plus important de la cuticule, comme le montrent les évaluations MEB et la cohésion cuticulaire. Les cheveux sont également significativement plus fragiles (p <0,05), comme le montrent les tests de traction. De plus, ces femmes ont également des scores d'alopécie de traction plus élevés. Dans le cas spécifique du peignage répété, une tendance linéaire a été observée entre les dommages en surface de la fibre capillaire et le nombre de coups de peigne. On peut également noter que l'endommagement de la cuticule causé par 480 coups de peigne est plus important que celui causé par des tressages fréquents. CONCLUSION: Les tressages et peignages fréquents endommagent les cheveux naturels d'origine Africaine. La quantification des dommages causés par différentes pratiques cosmétiques met en évidence le besoin de développer des produits qui pourraient aider à atténuer les dommages liés à des pratiques spécifiques. Le niveau de dommage et la perte de cheveux pourraient également être minimisés par un apprentissage de meilleures pratiques de tressage pour protéger la fibre et éviter la diminution des follicules pileux causée par des coiffures qui entrainent un forte traction sur la fibre.

Dark cyclobutane pyrimidine dimers are formed in the epidermis of Fitzpatrick skin types I/II and VI in vivo after exposure to solar-simulated radiation.

INTRODUCTION: Unlike "light" cylobutane pyrimidine dimers (CPD) formed during ultraviolet radiation (UVR) exposure, dark CPD (dCPD) are formed afterwards. Studies have attributed this to delayed melanin sensitization. There are no data on the role of melanin in dCPD formation in human skin. METHODS AND RESULTS: Volunteers of Fitzpatrick skin types (FST I/II vs. VI) were exposed to erythemally equivalent doses of solar simulated radiation. CPD were assessed by semi-quantitative immunostaining in whole epidermis and in three epidermal zones, and quantitative HPLC-MS/MS (whole epidermis) at different times post-exposure up to 24 hr. A CPD peak that appeared at 1-2 hr post-exposure in whole epidermis measurements, in all skin types, demonstrated dCPD. However, both dCPD and light CPD were absent in the basal layer of FST VI with the greatest melanin concentration. Modelling the whole epidermis data showed no differences between the repair kinetics of FST I/II and VI. DISCUSSION: Melanin may be a sensitizer or "sunscreen" for dCPD depending on its location and concentration. Previous CPD repair studies in human skin have assumed peak CPD immediately after UVR exposure and so have overestimated total repair.

Sunburn and sun protection in black skin.

BACKGROUND: People with black skin are much less susceptible to sunburn than white-skinned individuals, yet there are scarce data on self-reported incidence of sunburn and sun protection measures in people with deeply-pigmented skin. METHOD: An on-line survey tool was used to collect self-assessed data about demographic variables, sunburn incidence, and use of sun protection modalities. RESULTS: Two-thirds of respondents with black skin living in the UK claimed never to have been sunburnt; a much higher proportion than those living in South Africa and Nigeria where 34 and 46%, respectively, reported never experiencing sunburn. Similar results were seen in the reported use of sun protection measures between the countries with two-thirds of black people living in the UK claiming they never used any form of sun protection compared with about one-third of Black Africans. Black people living in the UK were more likely to use sunscreen as a form of sun protection, whereas sunscreen was the least popular modality in the two African countries with shade being the most common form of limiting sun exposure. CONCLUSION: The findings provide some insight into the complexities of skin color perception, incidence of sunburn, and sun protection use among people with deeply-pigmented skin living in three countries with large differences in the solar UV environment.

Diffuse Reflectance Spectroscopy as a Reliable Means of Comparing Ultraviolet Radiation-induced Erythema in Extreme Skin Colors.

Erythema is widely considered an indicator of skin cancer susceptibility, but assessments are challenging in black skin because melanin can mask erythema under traditional visual and advanced objective Commission Internationale de l'Eclairage (CIE) L*a*b* assessments. Using spectral measurements (400-700 nm) from a spectrophotometer, an algorithm was developed to measure erythema in white Caucasians (n = 9) and black West Africans (n = 11) 19-24 h postsolar simulated radiation (SSR) exposures to the volar forearm. The derived spectrum achieved showed a strong maximum peak for hemoglobin at 580 nm and a linear slope between 650 and 700 nm for melanin absorption, as reported by other authors. Absorption by hemoglobin at 580 nm was used as a proxy for erythema, and melanin was quantified between 650 and 700 nm. Our algorithm corrected the erythema measurements for stray specular (mirror-like) reflection and the melanin-masking effect. A linear relationship between SSR exposure and erythema was evident (p < 0.0001 for white and black skin), and white skin is 8.4 times more responsive to SSR compared to black skin. The prediction of ultraviolet radiation sensitivity is vital in both clinical and investigative dermatology especially in the determination of starting phototherapy doses. Our methodology allows for the accurate assessment of erythema independent of constitutive pigmentation.

Melanin distribution in human epidermis affords localized protection against DNA photodamage and concurs with skin cancer incidence difference in extreme phototypes.

Epidermal DNA damage, especially to the basal layer, is an established cause of keratinocyte cancers (KCs). Large differences in KC incidence (20- to 60-fold) between white and black populations are largely attributable to epidermal melanin photoprotection in the latter. The cyclobutane pyrimidine dimer (CPD) is the most mutagenic DNA photolesion; however, most studies suggest that melanin photoprotection against CPD is modest and cannot explain the considerable skin color-based differences in KC incidence. Along with melanin quantity, solar-simulated radiation-induced CPD assessed immediately postexposure in the overall epidermis and within 3 epidermal zones was compared in black West Africans and fair Europeans. Melanin in black skin protected against CPD by 8.0-fold in the overall epidermis and by 59.0-, 16.5-, and 5.0-fold in the basal, middle, and upper epidermis, respectively. Protection was related to the distribution of melanin, which was most concentrated in the basal layer of black skin. These results may explain, at least in part, the considerable skin color differences in KC incidence. These data suggest that a DNA protection factor of at least 60 is necessary in sunscreens to reduce white skin KC incidence to a level that is comparable with that of black skin.-Fajuyigbe, D., Lwin, S. M., Diffey, B. L., Baker, R., Tobin, D. J., Sarkany, R. P. E., Young, A. R. Melanin distribution in human epidermis affords localized protection against DNA photodamage and concurs with skin cancer incidence difference in extreme phototypes.

The impact of skin colour on human photobiological responses.

Terrestrial solar ultraviolet radiation (UVR) exerts both beneficial and adverse effects on human skin. Epidemiological studies show a lower incidence of skin cancer in people with pigmented skins compared to fair skins. This is attributed to photoprotection by epidermal melanin, as is the poorer vitamin D status of those with darker skins. We summarize a wide range of photobiological responses across different skin colours including DNA damage and immunosuppression. Some studies show the generally modest photoprotective properties of melanin, but others show little or no effect. DNA photodamage initiates non-melanoma skin cancer and is reduced by a factor of about 3 in pigmented skin compared with white skin. This suggests that if such a modest reduction in DNA damage can result in the significantly lower skin cancer incidence in black skin, the use of sunscreen protection might be extremely beneficial for susceptible population. Many contradictory results may be explained by protocol differences, including differences in UVR spectra and exposure protocols. We recommend that skin type comparisons be done with solar-simulated radiation and standard erythema doses or physical doses (J/m2 ) rather than those based solely on clinical endpoints such as minimal erythema dose (MED).