Greying of the human hair: A worldwide survey, revisiting the '50' rule of thumb

ArticleinBritish Journal of Dermatology 167(4):865-73 · June 2012with 1,978 Reads 
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Abstract
Summary Background While numerous papers have reported on the biological mechanisms of human hair pigmentation and greying, epidemiological descriptions of both natural hair colour and the greying process, worldwide, remain scarce. Objectives To assess hair colour and greying in a large world sample of human subjects, and to revisit the validity of the 50/50/50 rule of thumb, which states that ‘at age 50 years, 50% of the population has at least 50% grey hair’. Methods The natural hair colour of 4192 healthy male and female volunteers was assessed using a sensorial expert evaluation through the comparison of each volunteer’s hair with standard swatches. Hair colour was studied according to age, gender and ethnic or geographical origin. Results Overall we observed that between 45 and 65 years of age, 74% of people were affected by grey hair with a mean intensity of 27%. Men harboured significantly more grey hair than women. Both age at onset and rate of greying with age appeared to be clearly linked to ethnic/geographical origin. Subjects of Asian and African descent showed less grey hair than those of caucasian origin, at comparable ages, confirming previously reported data. Conclusions Calculating the percentage of people showing at least 50% grey hair coverage at age 50 years leads to a global range of 6–23%, according to ethnic/geographical origin and natural hair colour: well below that expressed by the ‘50’ rule of thumb.

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  • ... According to famous 50s rule of thumb, 50% of the population has at least 50% gray hair at 50 years old, but Panhard et al. reported that 6---23% of the population has at least 50% gray hair at 50 years old. 4,18 In a previous study conducted around the world, it was reported that incidence of HG in same age groups was very low in sub-Saharan African and African-Americans than other ethnic origins and severity of HG was the lowest in the African and Asian groups and the highest in the European group. 18 The frequency and 19 HG usually starts at around 40 years but it may start at any age. ...
    Article
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    Background Hair graying is common in humans; but there is scarce data about its epidemiology. Objective This study aimed to evaluate the clinical and epidemiological characteristics and associated factors of Hair graying. Methods A total of 1541 volunteers between 15 and 65 years old were included in this population-based, cross-sectional study. A questionnaire on characteristics and associated factors of Hair graying were filled in by face-to-face interview method. Results One thousand sixty three participants (69.0%) had Hair graying. The mean onset age of Hair graying was 32.9 ± 9.8 years. It was 31.7 ± 9.5 years in females, whereas 33.7 ± 10.0 years in males (p = 0.001). The most common involved area of Hair graying at the onset and at the present was temporal region. When it was evaluated by gender, it was temporal in males whereas parietal in females. Hair graying was more severe in males than in females and in late-onset Hair graying than early-onset Hair graying (respectively, p = 0.000, p < 0.001). The most common involved area at the onset and at the present was temporal in severe Hair graying; whereas parietal in mild Hair graying. In logistic regression analysis, age, educational status, presence of hair loss, skin type, family history of early-onset Hair graying and anxiety were independently related to Hair graying (p < 0.05). Study limitations The study was performed in only Turkish individuals. The recall biases were another limitations. Conclusion Male gender, late-onset and temporal-onset of Hair graying may be considered to be poor prognostic factors for Hair graying. There is need for further epidemiological studies in people with different ethnic origin to illuminate the clinical and epidemiological characteristics and associated factors of Hair graying.
  • ... Grey hair is widespread amongst 95 elderly and middle-aged people. A study of 23 different ethnic groups found that 74% of people between the ages of 45 and 65 had some measure of grey hair (Panhard, Lozano & Loussouarn, 2012). Moreover, developing grey hair in one's twenties is not uncommon (Ortonne, 1990). ...
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    Hair colour is a potent signifier of age. We explore how women negotiate stereotyping and ageism through their decisions either to dye their hair and pass for younger and reap the benefits of doing so, in and out of the workplace, or to resist societal pressure to conform to unrealistic beauty standards and wear their natural hair colour.
  • ... There is a traditional 50/50/50 rule of thumb, which states that “at age 50 years, 50% of the population has at least 50% gray hair.” However, in a recent study calculating the percentage of people showing at least 50% gray hair coverage at age 50 years, leads to a global range of 6-23%, according to ethnic, geographical origin and natural hair color that this percentage has been well below that expressed by the ‘50’ rule of thumb.[5] ...
    Article
    Osteoarthritis (OA) is the most common form of arthritis and one of the causes of pain and disability. The hair graying characteristic correlates strictly with chronological aging and take places to varying degrees in all individuals, disregarding gender or race. Comparison of the degrees of clinical and radiologic severity of the knee OA in individuals with early hair graying compared to ordinary individuals. A total of 60 patients with knee OA and similar demographic characteristics were enrolled in this study. All patients were classified in to 3 age subgroups in each of the case and control groups (30-40 year, 41-50 year, 51-60 year). In the case group, the patients must had early hair graying, too. Knee OA were classified using the Kellgren-Lawrence (KL) grading scale. Western Ontario McMaster University Osteoarthritis index (WOMAC) was applied to assess clinical severity of the knee OA. The mean ± SD of WOMAC index in the case group was 60.7 ± 15.9 and in the control group was 55.3 ± 15.3 (P = 0.1). The mean rank of KL scale in case group was 35.3 and in the control group was 25.6 (P = 0.02). Even at the same age of OA onset, the rate of progression of radiological findings and the grade of joint destruction in individuals with early hair graying are greater than normal individuals. However, clinical and functional relevant remain unclear.
  • ... A recent worldwide survey showed that 74% of people between the ages of 45 and 65 have grey hair, and that occurs earliest in people of Caucasian descent, followed by Asians and Africans [1]. Hair is considered to grey prematurely only if it occurs before the age of 20 years in Whites, before 25 years in Asians and before 30 years in Africans [2]. ...
    Article
    Full-text available
    Intricate coordinated mechanisms that govern the synchrony of hair growth and melanin synthesis remain largely unclear. These two events can be uncoupled in prematurely gray hair, probably due to oxidative insults that lead to the death of oxidative stress-sensitive melanocytes. In this study, we examined the gene expression profiles of middle (bulge) and lower (hair bulb) segments that had been micro-dissected from unpigmented and from normally pigmented hair follicles from the same donors using quantitative real-time RT-PCR (qPCR) arrays. We found a significant down-regulation of melanogenesis-related genes (TYR, TYRP1, MITF, PAX3, POMC) in unpigmented hair bulbs and of marker genes typical for melanocyte precursor cells (PAX3, SOX10, DCT) in unpigmented mid-segments compared with their pigmented analogues. qPCR, western blotting and spin trapping assays revealed that catalase protein expression and hydroxyl radical scavenging activities are strongly repressed in unpigmented hair follicles. These data provide the first clear evidence that compromised antioxidant activity in gray hair follicles simultaneously affects mature hair bulb melanocytes and their immature precursor cells in the bulge region.
  • ... In 1933, Rev. C. Ashlin West writes in a journal on human genetics, 'Sir, For quite a number of years I have interested myself in the phenomena of "premature" grey hair, and am convinced that in many instances this kind of hair, the despair of the ladies, and the horror of business men, is not the outcome of any other than natural factors and that it is not a sign of prematurity, but rather the sign that germinal factors have been at work (West, 1933)'. Indeed, in humans, epidemiological data repeatedly demonstrate a variable genetic component to hair graying exemplified by differential onset with age based on race, with people of Asian and African descent graying later than Caucasians (Boas and Michelson, 1932;Keogh and Walsh, 1965;Panhard et al., 2012). Strong correlation between the amount of gray hair observed in monozygotic twins further suggests the influence of genetic factors on this phenotype (Gunn et al., 2009). ...
    Article
    Full-text available
    Hair graying in mouse is attributed to the loss of melanocyte stem cell function and the progressive depletion of the follicular melanocyte population. Single gene, hair graying mouse models have pointed to a number of critical pathways involved in melanocyte stem cell biology, however, the broad range of phenotypic variation observed in human hair graying suggests that additional genetic variants involved in this process may yet be discovered. Using a sensitized approach, we ask here whether natural genetic variation influences a predominant cellular mechanism of hair graying in mouse, melanocyte stem cell differentiation. We developed an innovative method to quantify melanocyte stem cell differentiation by measuring ectopically pigmented melanocyte stem cells in response to the melanocyte-specific transgene Tg(Dct-Sox10). We make the novel observation that the production of ectopically pigmented melanocyte stem cells varies considerably across strains. The success of sensitizing for melanocyte stem cell differentiation by way of Tg(Dct-Sox10) sets the stage for future investigations into the genetic basis of strain-specific contributions to melanocyte stem cell biology. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
  • ... From demographic or ethnologic viewpoints, such chart suggests that skin colours from A4 to F11 likely cover 80-90% of the world human population, whereas skin colours from A1 to F3 grossly represent the socalled Caucasian type. The same holds true for hair colour where black or brown shades (tones 1-3) are shared by more than 90% of the total population [50]. In brief, the eumelanin/black pigment clearly predominates within the skin and hair of Homo sapiens, whereas phaeomelanin/red-yellow pigment may be viewed as a mutation-induced pigment, as previously mentioned. ...
    Article
    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 out-dated phrasings used in its communication. As a second objective, it aims at proposing an alternative to these wordings. The latter would combine 6 shade-types, defined by Individual Type Angle (ITA) values, a coloured reference chart and associated colour adjectives, highly corresponding to the 6 Photo-types previously defined by Fitzpatrick. Such alternative would overcome most references to both ethnic and ethical related issues.This article is protected by copyright. All rights reserved.
  • ... Gray hair condition varies between individuals, worldwide, with various ages of incidence and distinct progression in magnitude ( Panhard et al., 2012). The graying of hair is due to a progressive depletion of melanocyte stem cells (MSC) in hair follicles, leading to the defect of the hair pigmentation unit renewal at the telogen to anagen transition during the hair cycle, and to the growth of white hair, eventually ( Commo et al., 2004a;Nishimura et al., 2005). ...
    Article
    Full-text available
    During the past decade, melanins and melanogenesis have attracted growing interest for a broad range of biomedical and technological applications. The burst of polydopamine-based multifunctional coatings in materials science is just one example, and the list may be expanded to include melanin thin films for organic electronics and bioelectronics, drug delivery systems, functional nanoparticles and biointerfaces, sunscreens, environmental remediation devices. Despite considerable advances, applied research on melanins and melanogenesis is still far from being mature. A closer intersectoral interaction between research centers is essential to raise the interests and increase the awareness of the biomedical, biomaterials science and hi-tech sectors of the manifold opportunities offered by pigment cells and related metabolic pathways. Starting from a survey of biological roles and functions, the present review aims at providing an interdisciplinary perspective of melanin pigments and related pathway with a view to showing how it is possible to translate current knowledge about physical and chemical properties and control mechanisms into new bioinspired solutions for biomedical, dermocosmetic, and technological applications.
  • ... Humans differ from other primates in having lost most terminal body hair (via hair follicle miniaturization), possibly in connection to the adaptive development of more efficient sweating, linked to bipedalism 2,3 . However, considerable head hair has been retained in modern humans and its appearance shows extensive variation between individuals [4][5][6] . Head hair appearance is highly heritable 7-10 and certain traits show high differentiation between continental native populations. ...
    Article
    Full-text available
    We report a genome-wide association scan in over 6,000 Latin Americans for features of scalp hair (shape, colour, greying, balding) and facial hair (beard thickness, monobrow, eyebrow thickness). We found 18 signals of association reaching genome-wide significance (P values 5 × 10(-8) to 3 × 10(-119)), including 10 novel associations. These include novel loci for scalp hair shape and balding, and the first reported loci for hair greying, monobrow, eyebrow and beard thickness. A newly identified locus influencing hair shape includes a Q30R substitution in the Protease Serine S1 family member 53 (PRSS53). We demonstrate that this enzyme is highly expressed in the hair follicle, especially the inner root sheath, and that the Q30R substitution affects enzyme processing and secretion. The genome regions associated with hair features are enriched for signals of selection, consistent with proposals regarding the evolution of human hair.
  • ... Insufficient synthesis of melanin leads to several human hypopigmentation disorders, such as hair graying and vitiligo (2). A recent study showed that 74% of people between 45 and 65 years of age have grey hair (3). Vitiligo is a frequent cause of depigmentation worldwide with an estimated prevalence of 1% (4). ...
    Article
    Full-text available
    Lactoferricin B (LfcinB), a peptide of bovine lactoferrin (LfB), exhibits multiple biological functions, including antimicrobial, antiviral, antioxidant and immunomodulatory activities. However, the role of LfcinB-related peptides in melanogenesis remains unclear. In this study, a set of five LfcinB-related peptides was examined. We found that LfB17‑34, an 18-mer LfcinB-derived peptide, increased melanogenesis in B16F10 melanoma cells without significantly affecting cell viability. LfB17‑34 increased in vitro tyrosinase activity and melanin content in a dose-dependent manner. The results of RT-qPCR and western blot analyses showed that LfB17‑34 increased the mRNA and protein expression of tyrosinase and tyrosinase-related protein 1 (Trp1). Moreover, LfB17‑34 inhibited the phosphorylation of MAPK/Erk, but not p38 and Akt, and constitutively active MEK was able to reverse the LfB17-34-enhanced pigmentation, melanin content, and tyrosinase activity, suggesting a role of Erk signaling in the process of LfB17‑34-mediated pigmentation. Taken together, these results suggest that LfB17‑34 induces melanogenesis in B16F10 cells primarily through increased tyrosinase expression and activity and that LfB17‑34 could be further developed for the treatment of hypopigmentation disorders.
  • ... [1] However, the validity of this 50/50/50 rule of thumb is doubtful, evidenced from the results of a survey conducted on 4192 healthy male and female volunteers, in which calculating the percentage of people showing at least 50% gray hair coverage at age 50 years lead to a global range of 6%-23%, according to ethnic/geographical origin and natural hair color, well below that expressed by the "50" rule of thumb. [13] Despite a strong genetic control and inheritance pattern of onset of hair graying, little is known about the mechanism(s) by which functional melanocytes are lost from anagen graying hair follicles. Graying of hair is believed to have a multifactorial etiology including a genetic component, environmental factors, endocrine abnormalities, and nutritional status, among others. ...
    Article
    Full-text available
    Background The incidence of self-reported premature hair graying (PHG) seems to be on the rise. PHG has a profound impact on the patient's quality of life. It remains an incompletely understood etiology with limited and modest treatment options. Aim The evaluation of the demographic and clinical profile of patients with premature canities, and exploration of the association of this entity with certain systemic disorders suspected to be related to its etiology. Methods Seventy-one cases of premature canities (onset noticed by patients before 25 years of age) presenting to an urban skin clinic in Gurugram, India, between September 2012 and September 2015 with this complaint were retrospectively analyzed. The patient records were retrieved that provided details of the onset, duration and pattern of involvement, history, and examination findings (scalp, cutis, and general physical). Since all these patients had been screened for anemia, thyroid disorder, fasting blood glucose, and Vitamin B12 levels at the time of presentation, these parameters were also available for analysis. Results The mean age at onset of graying was 10.2 ± 3.6 years (range: 5–19 years), with an almost equal gender distribution. The earliest age of onset recorded was 5 years. A positive family history of PHG (at least one of the biological parents or siblings) was obtained in 64 (90.1%) of the cases. The temporal regions of the scalp (35.2%) were most commonly involved followed by the frontal region (18.3%). Hypovitaminosis B12 and hypothyroidism showed significant association with the disorder, whereas anemia, serum ferritin, and fasting blood glucose did not. Conclusion The age of onset of hair graying can be as low as 5 years. Temporal and frontal areas are the most commonly involved sites. A strong family history, Vitamin B12 deficiency, and hypothyroidism are strongly associated with PHG. Larger case–control studies are mandated for discerning the correlation of these and other risk factors with PHG.
  • ... Weathering of hair shaft involves degeneration of hair fibres that develop from the root to the tip. Ageing hair follicles refers to decreased melanocyte function (known as greying) and decreased hair production [8]. Hair greying is a physiological phenomenon that is considered to be a natural age-associated feature. ...
    Article
    Full-text available
    BACKGROUND: Many researchers have been indicated that premature hair greying (PHG) may be associated with the multifactorial problem include genetic, trace elements deficiencies and some medical problems such as metabolic disorders. However, the risk factors for premature hair greying are not well known for young adult. AIM: This study aimed to determine the risk factors of hair greying in young adult. METHODS: We conducted a cross-sectional study recruited 100 respondents of a college student at the Universitas Sumatera Utara (USU) with the inclusion criteria: male, less than 25 years old with hair greying and not have skin pigmentation disorders. The questionnaires about greying of hair status, family history of greying and history of family disease were collected by self-report. RESULTS: The age of participants in this study was 20.09 ± 2.01 years (mean ± SD). The mean onset of PHG was 15.23 ± 3.52 years (range: 9 – 22 years). The family history of PHG was 39% with paternal in 262%; maternal in 10%% and both parents in 3%. There was a significant difference between several grey hairs with a family history of PHG P = 0.045. The family history with metabolic disorders; hypertension was 29%, obesity was 25%, and diabetes Mellitus (DM) was 15%. Limitations: Owing to the use of questionnaires, the possibility of recall bias exists. The young female was not evaluated in this study. CONCLUSION: The family history of PHG and onset of greying are important risk factors associated with PHG of a young adult.
  • ... In 2012, a survey was conducted to assess hair color and graying in a large worldwide sample of human subjects, according to ethnic/geographic origin and natural hair color. 27 The percentage of people at around the age of 50 years who had at least 50% gray hair was 6-23%, well below that expressed by the "50" rule of thumb in the Japanese population. 28 In our survey of vitiligo patients, 22.9% had moderate, 6.3% had a lot and 1.6% had all gray hair. ...
    Article
    Full-text available
    To assess the sociodemographic data and clinical information of outpatients affected by vitiligo in the northeast of China, vitiligo patients or guardians who presented to the clinic were invited to participate in an exploratory questionnaire. The questionnaire consisted of two sections related to vitiligo, including sociodemographic data and clinical information. A total of 983 vitiligo patients answered the questionnaire. The rates of female and male patients were comparable. The investigated patients were mostly young and middle-aged. Most patients suffered from vitiligo in childhood or young adulthood. Vitiligo vulgaris was the most common type of vitiligo in clinic and 53.0% of patients were categorized as body surface area (BSA) of 10% or less. In response to the latest treatment, 43.6% of patients achieved good response (completely stopped or almost disappeared). More patients at active stage showed good response than the patients at stable stage (χ2 = 7.866, P < 0.05). Chronic comorbid condition(s) were observed in 12.6% of patients with BSA of more than 10%, whereas those were seen in 6.0% of patients with BSA of 10% or less (χ2 = 12.969, P < 0.05). In conclusion, active vitiligo seems to respond better than stable vitiligo and complications with other autoimmune diseases more frequently observed in severe patients than mild patients. The current study presented a comprehensive understanding of vitiligo in the northeast of China.
  • ... In African Americans, onset is shifted to slightly later in life at 43.9 ± 10.3 years, whereas the late 30's are the rule for Asians. [2] Onset is defined as premature when graying starts before 20 in Caucasian, 25 in Asian, and 30 in Negro. [3,4] Canities may affect individual hair follicles with either gradual loss of pigment over time and over several cycles, gradual loss of pigment along the same hair shaft i.e. within the same anagen phase of a single hair cycle, or, the hair fiber may grow in fully depigmented. ...
    Article
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    Abstract: Background : Hair graying is an aging sign that was found to be associated with several systemic diseases like ischemic heart disease, osteopenia, and autoimmune diseases. Metabolic syndrome was applied to the clustering of risk factors that often associate with increased risk for atherosclerotic cardiovascular disease. Aim of Study : Our work aimed to test retrospectively the association between onset of hair graying and risk of metabolic syndrome. Patients & Methods : Four hundred and eighty one gray hair individuals, with no history of any type of atherosclerotic disease, participated in the study. They were recruited during the period extending from September 2016 to may2017, as inpatients from the medical and surgical wards in addition to outpatients from Department of Dermatology and Venereology of Baghdad Teaching Hospital. The participants have been divided into two groups according to the presence or absence of criteria of metabolic syndrome which were detected clinically and by investigation into control and metabolic syndrome groups, and each individual in both groups was asked about the decade (2 nd -6 th ) when he/she firstly noticed that he/she had a gray hair. A comparison was made regarding the age of onset of graying between the two groups. Results: This study showed significant difference in decades between individuals with metabolic syndrome and the control group and was found in the 4 th and 5 th decade of life; p values were 0.045 and 0.024 respectively while the difference was found to be non significant in the 2 nd , 3 rd and 6 th decades of life . The mean age of onset of hair graying in metabolic syndrome was (36.207 ±8.30 year) and the control group was (38.434 ±8.31 year), there is also a significant difference between the two groups (p value=0.003). Conclusion: patients with metabolic syndrome have an earlier age of onset of gray hair. Key words: Metabolic Syndrome, Hair graying. Introduction Graying of hair (canities) is usually a manifestation of the natural aging process and is thou
  • ... In African Americans, onset is shifted to slightly later in life at 43.9 ± 10.3 years, whereas the late 30's are the rule for Asians. [2] Onset is defined as premature when graying starts before 20 in Caucasian, 25 in Asian, and 30 in Negro. [3,4] Canities may affect individual hair follicles with either gradual loss of pigment over time and over several cycles, gradual loss of pigment along the same hair shaft i.e. within the same anagen phase of a single hair cycle, or, the hair fiber may grow in fully depigmented. ...
    Article
    Full-text available
    Background: Hair graying is an aging sign that was found to be associated with several systemic diseases like ischemic heart disease, osteopenia, and autoimmune diseases. Metabolic syndrome was applied to the clustering of risk factors that often associate with increased risk for atherosclerotic cardiovascular disease. Aim of Study: Our work aimed to test retrospectively the association between onset of hair graying and risk of metabolic syndrome. Patients & Methods: Four hundred and eighty one gray hair individuals, with no history of any type of atherosclerotic disease, participated in the study. The participants were divided into two groups according to the presence or absence of criteria of metabolic syndrome into control and metabolic syndrome groups, and each individual in both groups was asked about the decade (2 nd-6 th) when he/she firstly noticed that he/she had a gray hair. A comparison was made regarding the age of onset of graying between the two groups. Results: There was a significant difference in decades between individuals with metabolic syndrome and the control group and was found in the 4 th and 5 th decade of life (P =0.045 & 0.024 respectively) while the difference was not significant in the 2 nd , 3 rd and 6 th decades of life. The mean age of onset of hair graying in metabolic syndrome was 36.207 ± 8.30 year and the control group was 38.434 ±8.31 year, there is also a significant difference between the two groups (P value=0.003). Conclusion: patients with metabolic syndrome have an earlier age of onset of gray hair.
  • ... Third, the hair follicles enter a resting, dormant state called telogen (Figure 3.5). In a worldwide study, it has been calculated that 74% of people between 45 and 65 years of age are affected by hair greying (Panhard et al. 2012). An elegant by Nishimura and colleagues showed that defective self-maintenance of MSCs led to hair greying (Nishimura et al. 2005). ...
  • ... Hair graying is a common process occurring in people as they age. Fifty percent of the population has about 50% gray hair at the age of 50 years, known as the 50-50-50 rule 1,2 . Most non-pigmented hairs are white, attributable to total loss of melanin in the hair bulb. ...
    Article
    Full-text available
    Hair graying is an obvious sign of human aging. Although graying has been investigated extensively, the mechanism remains unclear. Here, we reviewed previous studies on the mechanism of graying and seek to offer some new insights. The traditional view is that hair graying is caused by exhaustion of the pigmentary potential of the melanocytes of hair bulbs. Melanocyte dysfunction may be attributable to the effects of toxic reactive oxygen species on melanocyte nuclei and mitochondria. A recent study suggests that bulge melanocyte stem cells (MSCs) are the key cells in play. Graying may be caused by defective MSC self-maintenance, not by any deficiency in bulbar melanocytes. Our previous study suggested that graying may be principally attributable to active hair growth. Active hair growth may produce oxidative or genotoxic stress in hair bulge. These internal stress may cause eventually depletion of MSC in the hair follicles. Taken together, hair graying may be caused by MSC depletion by genotoxic stress in the hair bulge. Hair graying may also be sometimes caused by dysfunction of the melanocytes by oxidative stress in the hair bulb. In addition, hair graying may be attributable to MSC depletion by active hair growth. Copyright © The Korean Dermatological Association and The Korean Society for Investigative Dermatology..
  • ... Spelled 'grey' by the British, and 'gray' by the Americans, it is defined as the change in hair colour that makes us feel older. While inaccurate, the commonly believed 'Rule of 50' (50% of 50-year-olds have about 50% grey hairs) [1] clearly emphasizes the mutual concern of our society in regards to hair greying. ...
    Article
    An obvious sign of aging is hair graying, or the loss of pigment production and deposition within the hair shafts. Numerous mechanisms, acting at different levels and follicular locations, contribute to hair graying, ranging from melanocyte stem cells defects to follicular melanocyte death. One key issue that is in common to these processes is oxidative damage. At the hair follicle stem cells niche, oxidative stress, accelerated by BCL-2 depletion, leads to selective apoptosis and diminution of melanocyte stem cells, reducing the repopulation of newly formed anagen follicles. Melanotic bulbar melanocytes express high levels of BCL-2 to enable survival from melanogenesis- and ultraviolet A (UVA)-induced reactive oxygen species (ROS) attacks. With aging, the bulbar melanocyte expression of anti-oxidant proteins like BCL-2, and possibly TRP-2, is reduced, and the dedicated enzymatic anti-oxidant defense system throughout the follicle weakens, resulting in enhanced oxidative stress. A marked reduction in catalase expression and activity results in milimolar accumulation of hydrogen peroxide, contributing to bulbar melanocyte malfunction and death. Interestingly, amelanotic melanocytes at the outer root sheath (ORS) are somewhat less affected by these processes, and survive for longer time even within the white, aging hair follicles. Better understanding of the over-time susceptibility of melanocytes to oxidative stress at the different follicular locations might yield clues to possible therapies for prevention and reversal of hair graying. This article is protected by copyright. All rights reserved.
  • ... Hair greying (canities) is a natural physiological process that is closely related with aging. Recent epidemiologic studies of men and women of various ethnicities revealed that between 45 and 65 years of age, 74% of people were affected by grey hair with a mean intensity of 27% [1]. ...
    Article
    Objective Hair greying (i.e., canities) is a component of chronological aging and occurs regardless of gender or ethnicity. Canities is directly linked to the loss of melanin and increase in oxidative stress in the hair follicle and shaft. To promote hair pigmentation and reduce the hair greying process, an agonist of α‐melanocyte‐stimulating hormone (α‐MSH), a biomimetic peptide (palmitoyl tetrapeptide‐20; PTP20) was developed. The aim of this study was to describe the effects of the designed peptide on hair greying. Methods Effect of the PTP20 on the enzymatic activity of catalase and the production of H2O2 by Human Follicle Dermal Papilla Cells (HFDPC) was evaluated. Influence of PTP20 on the expression of melanocortin receptor‐1 (MC1‐R) and the production of melanin were investigated. Enzymatic activity of sirtuin 1 (SIRT1) after treatment with PTP20 was also determined. Ex vivo studies using human micro‐dissected hairs allowed to visualise the effect of PTP20 on the expression in hair follicle of catalase, TRP‐1, TRP‐2, Melan‐A, ASIP and MC1‐R. These investigations were completed by a clinical study on 15 human male volunteers suffering from premature canities. Results The in vitro and ex vivo studies revealed the capacity of the examined PTP20 peptide to enhance the expression of catalase and to decrease (30%) the intracellular level of H2O2. Moreover, PTP20 was shown to activate in vitro and ex vivo the melanogenesis process. In fact, an increase in the production of melanin was shown to be correlated with elevated expression of MC1‐R, TRP‐1 and Melan‐A, and with the reduction in ASIP expression. A modulation on TRP‐2 was also observed. The pivotal role of MC1‐R was confirmed on protein expression analyzed on volunteer's plucked hairs after 3 months of the daily application of lotion containing 10 ppm of PTP20 peptide. Conclusion The current findings demonstrate the ability of the biomimetic PTP20 peptide to preserve the function of follicular melanocytes. The present results suggest potential cosmetic application of this newly designed agonist of α‐MSH to promote hair pigmentation and thus, reduce the hair greying process. This article is protected by copyright. All rights reserved.
  • ... It is approximated that the average age at onset of hair greying is mid-30 s for Caucasians and mid-40 s for individuals of African descent [30]. Another study also concluded that the incidence of hair greying appears to depend mainly on the ethnic origin and reported that individuals of Asian and African descent have less grey hair than those of the same age of Caucasian descent [31]. These results support the hypothesis that earlier onset of hair greying is associated with PD; however, due to lack of data on the link between hair features and PD in groups of individuals of different ancestry, this association seems far-fetched. ...
  • ... If melanin is not produced, the hair turns pale and it leads to white hair [2]. The causes of white hair include genetic factors [3], physical stress [4], under-nutrition [4], and aging [5]. With aging, the cellular activity decreases and melanin synthesis also fails at the same time. ...
    Article
    Full-text available
    We observed that on long-term breeding, gp91phox-knockout (gp91phox−/−) mice developed white hair. Here, we investigate the origin of this hitherto unexplained phenomenon. Moreover, we investigated the effect of tranexamic acid administration on the hair color in gp91phox−/− mice. We administered tranexamic acid (about 12 mg/kg/day) orally to 9-week-old C57BL/6j (control) and gp91phox−/− mice, thrice a week for 12 months. Compared to control mice, gp91phox−/− mice showed more white hair. However, the concentrations of reactive oxygen species and the levels of interleukin (IL)-1β and transforming growth factor (TGF)-β in the skin were lower than those in the control group. Furthermore, increase in white hair was observed in the control mice upon administration of the IL-1β antagonist. On the other hand, administration of tranexamic acid led to brown colored hair on gp91phox−/− mice. Although tranexamic acid treatment did not alter the expression levels of melanocortin receptor 1 and agouti signaling protein on hair follicles, it increased the expression of mahogunin ring finger protein 1 (MGRN1) and collagen XVII. These results suggested that retention of black hair requires the gp91phox/ROS/IL-1β/TGF-β pathway and that elevated levels of MGRN1 and collagen XVII lead to brown hair in gp91phox−/− mice.
  • ... Hair graying may be classified as natural senile canities and premature graying. Natural senile canities usually has its onset after the age of 40 years and aggravates with the ongoing aging process (1). Unlike senile canities, premature graying occurs prior to the age of 25 years and is usually progressive and permanent (2,3). ...
    Article
    Premature hair graying, or canities, is a complex multi-factorial process with negative effects on affected individuals. The aim of the present study was to investigate the possible underlying mechanisms of premature hair graying at the genetic level. A total of 5 unrelated Han Chinese individuals presenting with premature hair graying (25-40 years old, with >1% hair affected) were enrolled in the present study. RNA sequencing was performed to identify gene expression changes between the follicular cells of grey and black hair from the cohort. A total of 127 differentially expressed genes (DEGs) were identified. These DEGs were overrepresented in categories associated with the pigmentation pathway, with a decreased expression of key genes responsible for melanin synthesis. Of note, the decreased expression of certain transcription factors and the increased expression of certain precursor microRNAs observed may explain for the downregulation of certain other DEGs, which were identified as their targets via Starbase v2 and Integrated Motif Activity Response Analysis. The DEGs were also enriched in terms associated with the nervous system, indicating that neural disturbances may also have certain roles in premature hair graying. Of note, five of the downregulated DEGs were associated with aging according to the JenAge Aging Factor Database. To the best of our knowledge, the present study was the first genome-wide survey of the gene expression profile associated with premature hair graying. Dysfunction of the melanin biosynthesis pathway is probably the direct cause of hair graying and the present results provide valuable clues for further functional and mechanistic investigation.
  • ... There is a rule of thumb known as the 50-50-50: about 50% of the population will have 50% of gray hairs by the age of 50. 25,26 However, hair graying does not happen at the same age in all phenotypes. In Caucasians with low phototypes, the age of onset is commonly 34 ± 9.6 years, while in Africans with high phototypes, the age of onset is 43.9 ± 10.3 years. ...
    Article
    Full-text available
    Hair follicles experience several changes with aging, the most noticeable of which is graying of the hair shaft due to loss of melanin. Additional changes in the diameter and length of the hair have contributed to the concept of senescent alopecia, which is different from androgenetic alopecia according to most. Graying happens in most individuals, although in different grades and starting at different ages. It is related to a decrease in the number, and in the activity of, the melanocytes of the hair bulb, which eventually completely disappear from the bulb of the white hair. Residual non active melanocytes remain in the outer root sheath and in the bulge, which allows for repigmentation of the hair under certain stimuli or conditions. This article is protected by copyright. All rights reserved.
  • ... The objective of this research is to automatically estimate the natural hair tone of a person. This feature is expressed as a value from 1 to 10, ranging from black hair to the lightest blond (see Figure 1), as described in [27]. This perceptually linear notation applies well to most natural hair, since their color is directly related to the two melanin pigments that are present in human hair and is bound by the color space of hair colors existing in na-ture [3]. ...
  • ... Graying of hair, also called canities or achromotrichia, is part of the natural aging process. It has been reported that worldwide 6-23% of people have 50% gray hair by 50 years of age [2]. Graying typically begins in the mid-30s for Caucasians, the late-30s for Asians, and the mid-40s for Africans [3][4][5]. ...
    Article
    Hair graying is a common sign of aging resulting from complex regulation of melanogenesis. Currently, there is no medical treatment available for hair repigmentation. In this article we review the literature on medication-induced hair repigmentation, discuss the potential mechanisms of action, and review the quality of the literary data. To date, there have been 27 studies discussing medication-induced gray hair repigmentation, including 6 articles on gray hair repigmentation as a primary objective, notably with psoralen treatment or vitamin supplementation, and 21 reports on medication-induced gray hair repigmentation as an incidental finding. Medications noted in the literature include anti-inflammatory medications (thalidomide, lenalidomide, adalimumab, acitretin, etretinate, prednisone, cyclosporin, cisplatinum, interferon-α, and psoralen), stimulators of melanogenesis (latanoprost, erlotinib, imatinib, tamoxifen, and levodopa), vitamins (calcium pantothenate and para-amino benzoic acid), a medication that accumulates in tissues (clofazimine), and a medication with an undetermined mechanism (captopril). Diffuse repigmentation of gray hair can be induced by certain medications that inhibit inflammation or stimulate melanogenesis. There is also low-quality evidence that some vitamin B complex supplementation can promote gray hair darkening. While these compounds are not currently indicated for the treatment of gray hair, their mechanisms shed light on targets for future medications for hair repigmentation.
  • Article
    Background: The exact etiology of premature hair graying (PHG) remains unknown; however, oxidative stress is shown to be involved. Selenium, as an antioxidant, is widely known for its antiaging potentials. Moreover, PGH is more prevalent among addicts and because Lead is a common impurity found in illegal drug. Aims: We evaluated the serum levels of lead and selenium in patients with PHG and compared it with a control group. Patients/methods: In this cross-sectional study, 60 patients referred to Dermatology Clinic of Imam-Reza Hospital of Mashhad, Iran in 2015 were evaluated in two groups with and without PHG. Demographic information and disease characteristics, skin phenotype, and family history of PHG were recorded. Furthermore, 5 mL of brachial blood was drawn for measuring selenium and lead levels. Results: The mean patients' age was 28.1 ± 4.8 years. Age, sex, occupation, and skin phenotype in individuals with and without PHG were not significantly different (P > .05) but family history of PHG was significantly higher in the patients with PHG (P = .001). Similarly, the number of white hairs was significantly higher (P < .001), and the age of onset of hair graying was significantly lower in patients with PHG (P < .001). Serum levels of selenium and lead were not significantly different between two groups (P < .05). However, the serum levels of lead in the patients with PHG were slightly higher. Conclusions: The results of this study showed that there was no significant difference in lead and selenium serum levels in patients with and without PHG.
  • Chapter
    Patients often have a number of questions regarding changes in their hair. This chapter contains the most common questions patients ask as well as the answers to these questions. The chapter discusses basic information about hair growth and loss; age-related hair problems; effect of nutrition and lifestyle choices on hair; specific diagnoses including androgenetic alopecia, alopecia areata, cicatricial alopecia, and seborrheic dermatitis; and, finally, common treatment questions.
  • Article
    Christoffersen and coworkers1 reported that earlobe crease, xantelasmata, and crown top and frontoparietal baldness are associated with the increased risk of ischemic heart disease, myocardial infarction, and total death independently of several cardiovascular, socioeconomic, and lifestyle risk factors. Crude estimates and estimates adjusted for age suggested that moderate to complete graying of hair, facial wrinkles, and arcus corneae are also associated with the end points; gray hair remained a predictor after age and sex adjustments, but became nonsignificant after multifactorial adjustments.1 Although Christoffersen and coworkers1 stated that no other study associates gray hair with the risk of myocardial infarction, we have found such an …
  • Article
    Objective: 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 spectro-colorimeter 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 amongst 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. This article is protected by copyright. All rights reserved.
  • Article
    The appearance of human scalp hair is often tied to perceptions of youth and virility, especially in men. Hair loss, or alopecia and hair graying are commonly associated with advancing age and are frequently a source for emotional distress and anxiety. Our understanding of the complex molecular signals and mechanisms that regulate and influence the hair follicle has expanded in recent years. By harnessing this understanding we are poised to address the esthetic concerns of aging hair. Additionally, changes in the hair follicle may be a reflection of systemic senescent signals, thus because of its accessibility, the hair follicle may serve as an important research tool in gerontology. In this review, the most current knowledge and research regarding mechanisms of androgenetic alopecia, senescent alopecia, and graying are discussed, as are extrinsic factors that may contribute to hair changes with age. Evidence based management strategies for treatment of age-related hair changes are also reviewed. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
  • Article
    Humans are social animals that communicate disproportionately via potent genetic signals imbued in the skin and hair, including racial, ethnic, health, gender, and age status. For the vast majority of us, age-related hair pigment loss becomes the inescapable signal of our disappearing youth. The hair follicle (HF) pigmentary unit is a wonderful tissue for studying mechanisms generally regulating aging, often before this becomes evident elsewhere in the body. Given that follicular melanocytes (unlike those in the epidermis) are regulated by the hair growth cycle, this cycle is likely to impact the process of aging in the HF pigmentary unit. The formal identification of melanocyte stem cells in the mouse skin has spurred a flurry of reports on the potential involvement of melanocyte stem cell depletion in hair graying (i.e., canities). Caution is recommended, however, against simple extrapolation of murine data to humans. Regardless, hair graying in both species is likely to involve an age-related imbalance in the tissue's oxidative stress handling that will impact not only melanogenesis but also melanocyte stem cell and melanocyte homeostasis and survival. There is some emerging evidence that the HF pigmentary unit may have regenerative potential, even after it has begun to produce white hair fibers. It may therefore be feasible to develop strategies to modulate some aging-associated changes to maintain melanin production for longer.
  • Article
    Much like an individual's hairstyle, hair fibers along the scalp see a number of changes over the course of one's lifetime. As the decades pass, the shine and volume synonymous with youthful hair may give way to thin, dull, and brittle hair commonly associated with aging. These changes are a result of a compilation of genetic and environmental elements influencing the cells of the hair follicle, specifically the hair follicle stem cells and melanocytes. Telomere shortening, decrease in cell numbers, and particular transcription factors have all been implicated in this process. In turn, these molecular alterations lead to structural modifications of the hair fiber, decrease in melanin production, and lengthening of the telogen phase of the hair cycle. Despite this inevitable progression with aging, there exists an array of treatments such as light therapy, minoxidil, and finasteride which have been designed to mitigate the effects of aging, particularly balding and thinning hair. Although each works through a different mechanism, all aim to maintain or potentially restore the youthful quality of hair.
  • Article
    Context: Premature canities is a common, yet unexplored disorder. Oxidative stress levels have been evaluated within the greying hair follicle but not in the sera of patients with premature canities. Aims: To evaluate the oxidative stress parameters in the sera of patients with premature canities. Settings and design: A pilot case-controlled study, conducted in a tertiary care setup in Delhi during November 2011 to December 2012. Materials and methods: Fifty-two self-reporting cases of premature canities (age of onset <20 years) and 30 healthy controls were recruited from outpatient Department of Dermatology. Oxidative stress parameters (serum malonaldehyde (MDA), whole blood reduced glutathione (rGSH) and serum ferric reducing antioxidant potential [FRAP]) were assessed in cases and controls. Mann-Whitney test was used to compare the oxidative stress parameters between the two groups (SPSS version 17.0, SPSS Inc, Chicago, USA; P < 0.05 considered as significant). Results: The age and sex distribution of cases and controls was comparable. The mean serum levels of MDA were higher in cases than controls (3.7 ± 1.6 nmol/ml vs. 2.8 ± 1.5 nmol/ml; P = 0.01). The GSH levels were lower in the cases than controls (31.5 ± 8.9 mg/dl vs. 36.6 ± 16.9 mg/dl; P = 0.064). Similarly, the mean FRAP levels were lower in the cases than controls (400 ± 70 nmol/ml vs. 430 ± 80 nmol/ml; P = 0.038). Conclusions: Patients with premature canities had a higher level of pro-oxidants and lower levels of antioxidants than controls. This is the first humble attempt to document the oxidative stress parameters in sera of patients with premature canities, further studies with larger sample size are required to reach a definite conclusion.
  • Article
    Cutaneous science has seen considerable development in the last 25 years, in part due to the Omics revolution, and the appreciation that this organ is hardwired into the body's key neuro-immuno-endocrine axes. Moreover, there is greater appreciation of how stratification of skin disorders will permit more targeted and more effective treatments. Against this has been how the remarkable extension in the average human life-span, though in the West at least, this parallels worrying increases in lifestyle-associated conditions like diabetes, skin cancer etc. These demographic trends bring greater urgency to finding clinical solutions for numerous age-related deficits in skin function caused by extrinsic and intrinsic factors. Mechanisms for aging skin include the actions of reactive oxygen species (ROS), mtDNA mutations, and telomere shortening, as well as hormonal changes. We have also significantly improved our understanding of how to harness the skin's considerable regenerative capacity e.g., via its remarkable investment of stem cell subpopulations. In this way we hope to develop new strategies to selectively target the skin's capacity to undergo optimal wound repair and regeneration. Here, the unsung hero of the skin regenerative power may be the humble hair follicle, replete with its compliment of epithelial, mesenchymal, neural and other stem cells. This review introduces the topic of human skin aging, with a focus on how maintenance of function in this complex multi-cell type organ is key for retaining quality of life into old age.
  • Article
    Context: Although the primary cause of premature hair graying (PHG) is considered to be genetic, certain environmental factors also play a role. Trace element deficiencies such as Vitamin B12, Vitamin D3, and calcium may also be associated with PHG. However, India-specific data are relatively sparse. Aims: The present study aimed at identifying factors associated with PHG in Indian patients. Settings and design: A case-control study was conducted at a trichology clinic in Bengaluru between October 2013 and April 2014 with a total of 37 cases of PHG and 37 age- and gender-matched controls. Materials and methods: A total of 100 subjects were investigated for various parameters such as hemoglobin, serum ferritin, zinc, copper, calcium, Vitamin B12, and Vitamin D after obtaining informed consent. Statistical analysis used: Chi-square test was used to compare proportions between groups. Means were compared between groups using Student's t-test. Results: Serum ferritin levels were lower in patients with PHG as compared to the control group and the differences were statistically significant (P < 0.001). Furthermore, as compared to the controls, patients with PHG had lower serum Vitamin B12 levels (P < 0.001). Individuals with PHG had significantly lower levels of high-density lipoprotein cholesterol (HDL-C) as compared to the control group (P < 0.001). Significant proportions of patients with PHG had a sedentary lifestyle and admitted to having irregular eating habits. Conclusion: PHG is associated with low serum ferritin, Vitamin B12, and HDL-C levels in Indian patients aged <25 years. However, studies with large sample sizes may be required to conclusively define these putative associations.
  • Article
    Biomedicine has not provided a complete explanation with fully effective therapies for disorders of pigmentation. Biomedicine emphasizes the role of melanocyte for protection from UV rays and as a determinant of skin colour. These important properties acquired a genetic basis much later than other functions, many relating to cell contact as in the keratinocyte - melanocyte unit, or as with the synapses of the neurological system. There are other roles, biochemical and mechanical, of melanocyte. Management that is inclusive of a maximally holistic approach justifies the use of diverse herbals, yoga and concern for cultural awareness provided by integrated medicine. Vitiligo provides a model which demonstrates that Ayurveda has a richer view of its presentations, possibly a stronger line on its pathogenesis, and a huge range of herbals, many now backed by studies from ethnobotanical laboratories, awaiting research into the many possible mechanisms by which they may act in the wide and complex field of melanocyte biochemistry.
  • Article
    Human scalp hair is one of the most common trace materials found at violent crime scenes. Accordingly, scalp hair is critical evidential material in forensic investigations for identifying relations and persons, which could result in solving cases. Knowledge about micro-morphological variations of scalp hair in the Thai population, however, is scarce, and information on age changes and sex differences with respect to these traits is limited. The present study was thus undertaken to explore three micro-morphological parameters of Thai scalp hair—hair index (HI), hair area (HA), medullary index (MI)—relative to age and sex differences. Scalp hair samples were collected from 340 unrelated Thai cadavers (170 male, 170 female) of all ages, which were divided into seventeen age groups, 5-year-old interval per group beginning with 0 − 5 years and end up with ≥80 years. Approximately 30 hair strands at the posterior vertex region of the scalp were cut with scissors as close to the scalp as possible. The hair samples were subsequently used to make permanent slides, and the mounted hairs were examined for microscopic cross-sectional characteristics. The authors found that the HI and MI were similar in the male and female cadavers and did not significantly differ (p > 0.05) according to age. In contrast, the HA was significantly different between the male and female cadavers at 50 − 79 years of age (p < 0.05). There were other differences according to age as well. That is, the HA increased abruptly during their early twenties and then decreased gradually until ≥80 years of age. Thus, Thai scalp hair shows some age and sex variations that are reflected in the HA and might be useful for forensic, medical, and anthropological investigations.
  • Article
    Melanocyte stem cells (McSCs) are localized in the bulge region of hair follicles and supply melanocytes, which determine hair color by synthesizing melanin. Ectopic differentiation of McSCs, which are usually undifferentiated in the bulge region, causes depletion of McSCs and results in hair graying. Therefore, to prevent hair graying, it is essential to maintain McSCs in the bulge region, but the mechanism of McSC maintenance remains unclear. To address this issue, we investigated the role of CXCL12, a chemokine which was previously suggested to induce migration of melanocyte lineage cells, as a niche component of McSCs. Immunohistological analysis revealed that CXCL12 was highly expressed in the bulge region of human hair follicles. CXCL12 mRNA expression level was significantly lower in white hairs plucked from human scalps than in black hairs. CXCL12 attracted the migration of early-passage normal human epidermal melanocytes (eNHEMs), an in vitro model of McSCs, which had characteristics of immature melanocyte precursors. We also found that CXCL12 suppressed their differentiation. These results suggest that CXCL12 regulates differentiation of McSCs as well as their proper localization, and maintaining McSCs by regulating CXCL12 expression level in the bulge region may be a key to preventing hair graying.
  • Chapter
    Age-induced hair graying (canities), or the age-induced loss of melanin synthesis and deposition within the hair shafts, is a noticeable and undesired sign of the aging process. Numerous mechanisms contribute to age-induced hair graying, affecting both follicular and stem cell melanocytes and acting at different follicular locations. Many of these processes are induced, directly or indirectly, by oxidative insults and damage. Melanin-producing bulbar melanocytes express high levels of BCL-2 to survive reactive oxygen species (ROS) attacks, which are induced by the melanogenic process itself and by ultraviolet A (UVA) irradiation. With aging, the expression of BCL-2, and possibly of TRP-2, is reduced, and the endogenous, enzymatic antioxidant defense system declines, resulting in greater oxidative stress. In particular, catalase expression and activity are markedly reduced with aging, leading to millimolar accumulation of hydrogen peroxide within the hair follicle and contributing to bulbar melanocyte failure and death. Additionally, exposure of melanocyte stem cells to cumulative oxidative damage, combined with reduced BCL-2 protective levels, results in apoptosis and therefore decreases the number of melanocytes that could repopulate the newly formed anagen follicles. Altogether, oxidative stress may contribute to age-induced hair graying via multiple pathways. Better understanding of the different processes, sources, and types of oxidative stress within the follicular environment, and the different susceptibilities of melanocytes to oxidative stress at the different follicular locations, might yield clues to possible interventions for prevention or reversal of hair graying.
  • Article
    Objective: To examine the ability of an extract from traditional Chinese medicine, Polygonum multiflorum Radix, to protect melanocyte viability from oxidative stress, a key mechanism in the initiation and progression of hair greying. Methods: To assess the antioxidant capacity of Polygonum multiflorum Radix extract, primary human foreskin melanocytes were treated with a commercially available Polygonum multiflorum Radix extract added to culture medium and exposed to hydrogen peroxide (H2 O2 ), using intracellular reactive oxygen species concentrations and glutathione/protein ratios as endpoints. To improve solubility for cosmetic uses, a new Polygonum multiflorum Radix extract was derived. As hair graying is the consequence of melanocyte disappearance in an oxidative stress environment, we checked if the anti-oxidant capacity of the new Polygonum multiflorum Radix extract could preserve melanocyte viability in response to H2 O2 -induced oxidative stress, and preserve pigmentation within ex vivo human hair follicles. Results: In vitro treatment of primary human foreskin melanocytes with traditional available Polygonum multiflorum Radix extract resulted in decreased intracellular ROS accumulation in response to H2 O2 exposure with a concomitant preservation of glutathione to protein ratio, consistent with a protective response against H2 O2 exposure and demonstrating the promise of this extract for protecting melanocytes against oxidative stress. Melanocytes treated with the improved Polygonum multiflorum Radix extract exhibited attenuated H2 O2 -induced cell death, demonstrating a clear cytoprotective effect. Treatment of ex vivo human hair follicles with the improved Polygonum multiflorum Radix extract resulted in a higher level of melanin compared to vehicle-treated controls, demonstrating an ex vivo protective effect on hair pigmentation. Conclusion: Polygonum multiflorum Radix extract protects in vitro primary human foreskin melanocytes from the deleterious effects of H2 O2 -exposure and improves pigmentation within ex vivo human hair follicles, demonstrating the utility of Polygonum multiflorum Radix extract as a potential active ingredient for the protection of melanocytes against premature death. This data provides in vitro mechanistic evidence consistent with existing in vivo studies for the use of Polygonum multiflorum Radix extract as a strategy for the prevention of oxidative-stress induced hair greying, in line with traditional Polygonum multiflorum Radix uses. This article is protected by copyright. All rights reserved.
  • Chapter
    Age-induced hair graying (canities), or the age-induced loss of melanin synthesis and deposition within the hair shafts, is a noticeable and undesired sign of the aging process. Numerous mechanisms contribute to age-induced hair graying, affecting both follicular and stem cell melanocytes and acting at different follicular locations. Many of these processes are induced, directly or indirectly, by oxidative insults and damage. Melanin-producing bulbar melanocytes express high levels of BCL-2 to survive reactive oxygen species (ROS) attacks, which are induced by the melanogenic process itself and by ultraviolet A (UVA) irradiation. With aging, the expression of BCL-2, and possibly of TRP-2, is reduced, and the endogenous, enzymatic antioxidant defense system declines, resulting in greater oxidative stress. In particular, catalase expression and activity are markedly reduced with aging, leading to millimolar accumulation of hydrogen peroxide within the hair follicle and contributing to bulbar melanocyte failure and death. Additionally, exposure of melanocyte stem cells to cumulative oxidative damage, combined with reduced BCL-2 protective levels, results in apoptosis and therefore decreases the number of melanocytes that could repopulate the newly formed anagen follicles. Altogether, oxidative stress may contribute to age-induced hair graying via multiple pathways. Better understanding of the different processes, sources, and types of oxidative stress within the follicular environment, and the different susceptibilities of melanocytes to oxidative stress at the different follicular locations, might yield clues to possible interventions for prevention or reversal of hair graying.
  • Article
    Premature graying of hair has major psychosocial and socioeconomic repercussion, as it is considered as a sign of hastily progressing old age, ill health and often leads to loss of self‐esteem. Hair is said to gray prematurely when it happens before the age of 20 years in Caucasians, 25 years in Asians, and 30 years in Africans. The hair color chiefly depends on melanin pigment, and fabrication of this pigment takes place in melanosomes through the process of melanogenesis. This complex biochemical pathway (melanogenesis) is further dependent on tyrosinase which acts as fuel.The normal human scalp is subjected to various factors categorized as intrinsic and extrinsic leading to graying of hair. Intrinsic factors comprise of variants responsible for changes at genetic level while extrinsic factors include air pollution, ultraviolet radiation, smoking, and nutrition. It has been proposed that direct or indirect effect of all these factors results in the generation of reactive oxygen species (ROS), thus leading to further damage. Though research has expanded in last few years in terms of microscopic, biochemical (hormonal, enzymatic), and molecular changes happening within hair follicle/shaft, still the exact mechanism leading to premature graying of hair is not well understood. Probable solutions toward this quandary are diet, herbal remedies, and temporary hair colorants. Ironically, the latter one being the most common has various side effects such as allergic reactions, inflammation, and hair loss. The aim of this paper was to review the manifestation and probable future interventions in preventing premature hair graying.
  • Chapter
    Single nucleotide polymorphisms (SNPs) are the most frequent DNA sequence variations in the genome. They have been studied extensively in the last decade with various purposes in mind. In this chapter, we will discuss the advantages and disadvantages of using SNPs for human identification and briefly describe the methods that are preferred for SNP typing in forensic genetics. In addition, we will illustrate how SNPs can be used as investigative leads in the police investigation by discussing the use of ancestry informative markers and forensic DNA phenotyping. Modern DNA sequencing technologies (also called next-generation sequencing or NGS) have the potential to completely transform forensic genetic investigations as we know them today. Here, we will make a short introduction to NGS and explain how NGS may combine analysis of the traditional forensic genetic markers with analysis of SNPs. This will allow acquisition of more information from the sample materials and open up for new possibilities as well as new challenges. Keywords: single nucleotide polymorphism; forensic genetics; human identification; population genetics; ancestry informative marker; forensic DNA phenotyping; pigmentary traits
  • Article
    Hair pigmentation is regulated by follicular melanogenesis, in which the process consists of melanin formation and transfer to keratinocytes in the hair shaft. Human hair follicles contain two types of melanin: the brown‐black eumelanin and yellow‐red pheomelanin. Eumelanin is commonly present in black and brown hair while pheomelanin is found in auburn and blonde hair. Hair follicle melanogenesis is under cyclical control and is concurrently coupled to hair growth. Many factors including intrinsic and extrinsic factors affect the follicular melanogenesis. Though many studies have been conducted to identify the pathogenesis and regulation of hair pigmentation, the etiology of canities and hair pigmentation is still unclear. The pathogenesis of canities or gray hair is believed to occur either from insufficient melanin formation due to melanocyte degeneration or a defect in melanosomal transfer. Canities is an aging sign which often interferes with one's socio‐cultural adjustment. On the other hand, premature canities correlate with diseases such as osteopenia and cardiovascular disease. Risk factors associated with canities are not only genetic but also external causes. For example, smoking, alcohol consumption, and stress are among the most common factors. Camouflage techniques are still used as the primary treatment of canities. Further treatments for canities are being developed to achieve the true reversal of hair pigmentation.
  • Article
    Premature graying of hair (PGH) is defined as graying of hair before the age of 20 years in Caucasians and before 30 years in African American population. It can severely affect the self-esteem of an individual. The exact etiopathogenesis remains unknown, although it has been associated with premature aging disorders, atopy, and autoimmune diseases. Patients, who present with PGH, should be assessed for syndromes and metabolism diseases. Hair dyes remain the main modality of the treatment for cosmetic concerns after nutritional supplementation.
  • Article
    Full-text available
    Age-related hair graying is caused by malfunction in the regenerative potential of the adult pigmentation system. The retention of hair color over the life of an organism is dependent on the ability of the melanocyte stem cells and their progeny to produce pigment each time a new hair grows. Age-related hair graying is variable in association with genetic background suggesting that quantitative trait loci influencing this trait can be identified. Identification of these quantitative trait loci may lead to the discovery of novel and interesting genes involved in stem cell biology and/or melanogenesis. With this in mind we developed previously a sensitized, mouse modifier screen and discovered that the DBA/1J background is particularly resistant to melanocyte stem cell differentiation in comparison to the C57BL/6J background. Melanocyte stem cell differentiation generally precedes hair graying and is observed in melanocyte stem cells with age. Using quantitative trait loci analysis, we have now identified three quantitative trait loci on mouse chromosomes 7, 13, and X that are associated with DBA/1J-mediated variability in melanocyte stem cell differentiation. Taking advantage of publicly-available mouse sequence and variant data, in silico protein prediction programs, and whole genome gene expression results we describe a short list of potential candidate genes that we anticipate to be involved in melanocyte stem cell biology in mice.
  • Article
    Aim Premature hair graying (PHG) is commonly observed in society, but there are a few studies evaluating risk factors associated with PHG. We aimed to evaluate the socio‐clinical risk factors associated with PHG in this study. Methods A total of 1192 volunteers between 18 and 20 years old were included in this cross‐sectional study. Volunteers were asked to fill in a questionnaire on socio‐clinical risk factors associated with PHG such as smoking, alcohol consumption, diet preference, atopy history, and family history of PHG and Perceived Stress Scale (PSS). Results Three hundred and seventy‐seven (31.6%) of the 1192 volunteers had PHG. Vegetarian diet preference, atopy history, and family history of PHG were significantly higher in subjects with PHG. Mean body mass index (BMI) and PSS scores were higher in subjects with PHG, but was not statistically significant. In the ordinal logistic regression analysis according to severity of PHG, male gender, BMI, alcohol consumption, and history of paternal PHG were significantly higher and onset age of PHG was significantly lower in PHG group. Conclusion Our study is the first study reporting a relationship between PHG and diet. It may be possible to prevent PHG or reduce its severity with some lifestyle changes such as diet preference, having normal weight, and decreasing alcohol consumption.
  • Article
    Background Premature hair graying (PHG) is often a matter of great concern for patients as it is viewed as a sign of increasing age, debility, decreasing vigor, and may lead to low self-esteem and psychological morbidity. Its etiopathogenesis is not completely understood but genetic, and various acquired factors have been implicated. The present study was undertaken to evaluate various epidemiological and biochemical variables associated with PHG. Materials and Methods A cross-sectional case–control study was conducted at a tertiary care hospital in North India for 1 year which comprised 120 patients and equal number of controls. Various epidemiological variables were recorded and compared to controls. Serum ferritin, serum calcium, serum Vitamin D, serum Vitamin B12, lipid profile, thyroid profile, and fasting blood sugar were measured and compared among cases and controls. Results Significantly higher proportion of cases had atopic diathesis, sedentary lifestyle, family history, history of smoking, and higher perceived stress values as compared to controls. Hair oiling seemed to protect against premature graying. Significantly, lower levels of serum calcium, ferritin, Vitamin B12, high-density lipoprotein-cholesterol, and high low-density lipoprotein-cholesterol were observed among cases. Conclusion In the light of the present study, further studies with larger sample size are required to establish the definite etiological significance of these variables and formulate various preventive and therapeutic targets to prevent and treat PHG.
  • Article
    Hair graying and hair loss are prominent and common characteristics of the elderly population. In some individuals these processes can significantly impact their quality of life, leading to depression, anxiety and other serious mental health problems. Accordingly, there has been much interest in understanding the complex physiological changes within the hair follicle in the aging individual. It is now known that hair follicles represent a prototypical stem cell niche, where both micro- and macroenvironmental influences are integrated alongside stem cell-stem cell and stem cell-stem niche interactions to determine hair growth or hair follicle senescence. Recent studies have identified imbalanced stem cell differentiation and altered stem cell activity as important factors during hair loss, indicating new avenues for the development of therapeutic agents to stimulate hair growth. Here, we pull together the latest findings on the hair follicle stem cell niche and the multifactorial interactions underlying the various forms of hair loss.
  • Book
    The most comprehensive source on the subject, this Second Edition is completely revised and expanded to reveal the most recent advances, technologies, and trends in hair and hair care science-tracking the development of hair care products, the emergence of new regulatory practices, and the latest methods in product safety and efficacy assessment.
  • Article
    The editor, recognizing the indisputable interrelation between cosmetology and dermatology, has prepared a textbook designed to bridge the gap between these two disciplines. Physicians, in particular dermatologists, primarily provide such care as it relates to the treatment of diseases of the scalp and hair; cosmetologists are primarily concerned with enhancing the beauty of hair and scalp and improving hair hygiene. For many years a distinct line separated the types of care rendered by these professionals to their patients or clients. For obvious reasons, a fundamental understanding of scalp and hair pathology by cosmetologists and of the various hair-grooming and hygienic techniques by dermatologists is imperative, so that each group may render optimum care. However, the editor does not propose that cosmetologists administer treatment for diseases of the scalp and hair, nor does he intend for physicians and dermatologists to become proprietors of hair-care salons. I suspect such a textbook as
  • Article
    The melanocortin 1 receptor, a seven pass transmembrane G protein coupled receptor, is a key control point in melanogenesis. Loss-of-function mutations at the MC1R are associated with a switch from eumelanin to phaeomelanin production, resulting in a red or yellow coat colour. Activating mutations, in animals at least, lead to enhanced eumelanin synthesis. In man, a number of loss-of-function mutations in the MC1R have been described. The majority of red-heads (red-haired persons) are compound heterozygotes or homozygotes for up to five frequent loss-of-function mutations. A minority of red-heads are, however, only heterozygote. The MC1R is, therefore, a major determinant of sun sensitivity and a genetic risk factor for melanoma and non-melanoma skin cancer. Recent work suggests that the MC1R also shows a clear heterozygote effect on skin type, with up to 30% of the population harbouring loss-of-function mutations. Activating mutations of the MC1R in man have not been described. The MC1R is particularly informative and a tractable gene for studies of human evolution and migration. In particular, study of the MC1R may provide insights into the lightening of skin colour observed in most European populations. The world wide pattern of MC1R diversity is compatible with functional constraint operating in Africa, whereas the greater allelic diversity seen in non-African populations is consistent with neutral predictions rather than selection. Whether this conclusion is as a result of weakness in the statistical testing procedures applied, or whether it will be seen in other pigment genes will be of great interest for studies of human skin colour evolution.
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    Although we have made significant progress in understanding the regulation of the UVR-exposed epidermal-melanin unit, we know relatively little about how human hair follicle pigmentation is regulated. Progress has been hampered by gaps in our knowledge of the hair growth cycle's controls, to which hair pigmentation appears tightly coupled. However, pigment cell researchers may have overly focused on the follicular melanocytes of the nocturnal and UVR-shy mouse as a proxy for human epidermal melanocytes. Here, I emphasize the epidermis-follicular melanocyte pluralism of human skin, as research models for vitiligo, alopecia areata and melanoma, personal care/cosmetics innovation. Further motivation could be in finding answers to why hair follicle and epidermal pigmentary units remain broadly distinct? Why melanomas tend to originate from epidermal rather than follicular melanocytes? Why multiple follicular melanocyte sub-populations exist? Why follicular melanocytes are more sensitive to aging influences? In this perspective, I attempt to raise the status of the human hair follicle melanocyte and highlight some species-specific issues involved which the general reader of the pigmentation literature (with its substantial mouse-based data) may not fully appreciate.
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    Full-text available
    The desire of many to look young for their age has led to the establishment of a large cosmetics industry. However, the features of appearance that primarily determine how old women look for their age and whether genetic or environmental factors predominately influence such features are largely unknown. We studied the facial appearance of 102 pairs of female Danish twins aged 59 to 81 as well as 162 British females aged 45 to 75. Skin wrinkling, hair graying and lip height were significantly and independently associated with how old the women looked for their age. The appearance of facial sun-damage was also found to be significantly correlated to how old women look for their age and was primarily due to its commonality with the appearance of skin wrinkles. There was also considerable variation in the perceived age data that was unaccounted for. Composite facial images created from women who looked young or old for their age indicated that the structure of subcutaneous tissue was partly responsible. Heritability analyses of the appearance features revealed that perceived age, pigmented age spots, skin wrinkles and the appearance of sun-damage were influenced more or less equally by genetic and environmental factors. Hair graying, recession of hair from the forehead and lip height were influenced mainly by genetic factors whereas environmental factors influenced hair thinning. These findings indicate that women who look young for their age have large lips, avoid sun-exposure and possess genetic factors that protect against the development of gray hair and skin wrinkles. The findings also demonstrate that perceived age is a better biomarker of skin, hair and facial aging than chronological age.
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    Skin and hair colour contribute significantly to our overall visual appearance and to social/sexual communication. Despite their shared origins in the embryologic neural crest, the hair follicle and epidermal pigmentary units occupy distinct, although open, cutaneous compartments. They can be distinguished principally on the basis of the former's stringent coupling to the hair growth cycle compared with the latter's continuous melanogenesis. The biosynthesis of melanin and its subsequent transfer from melanocyte to hair bulb keratinocytes depend on the availability of melanin precursors and on a raft of signal transduction pathways that are both highly complex and commonly redundant. These signalling pathways can be both dependent and independent of receptors, act through auto-, para- or intracrine mechanisms and can be modified by hormonal signals. Despite many shared features, follicular melanocytes appear to be more sensitive than epidermal melanocytes to ageing influences. This can be seen most dramatically in hair greying/canities and this is likely to reflect significant differences in the epidermal and follicular microenvironments. The hair follicle pigmentary unit may also serve as an important environmental sensor, whereby hair pigment contributes to the rapid excretion of heavy metals, chemicals and toxins from the body by their selective binding to melanin; rendering the hair fibre a useful barometer of exposures. The recent availability of advanced cell culture methodologies for isolated hair follicle melanocytes and for intact anagen hair follicle organ culture should provide the research tools necessary to elucidate the regulatory mechanisms of hair follicle pigmentation. In the longer term, it may be feasible to develop hair colour modifiers of a biological nature to accompany those based on chemicals.
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    Melanin pigmentation plays an important part in adaptation to the environment. It protects against the carcinogenic effects of actinic radiation. As man migrated away from the tropics, the lightening of the species might have been due to a decreased need for this protection as well as to the need of a lighter skin to allow proper synthesis of vitamin D. New adaptations to sunnier climates might be accompanied by reverse darkening. The reason for the darkening of hair from infancy into adulthood needs studying as well as the differences in texture and coloring between scalp and beard hair. The sociological implications of skin pigmentation are serious. Sufferers from pigmentary disturbances need strong emotional support in addition to the standard forms of treatment.
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    Some of the physical and chemical properties of the melanins isolated from human black and red hair were compared. Some of these properties were also compared with those of synthetic dopa melanin. Five samples each of black and red hair were used for isolating melanin by extraction with 2.5 M NaOH, and purification by repeated precipitation with HCl and redissolution in NaOH. The proteins associated with the melanins were hydrolyzed by refluxing the melanoproteins in 6 M HCl. The melanoproteins from black and red hair had 55.8 ± 2.0% and 41.5 ± 2.5% melanin, respectively. There was no statistically significant difference between the amino acid compositions of the hydrolysates from black and red hair melanoproteins. The ultraviolet and visible spectra of red hair melanin showed significant differences from those of black hair melanin and dopa melanin. Even though the overall spectra of red hair melanin showed some differences from those of black hair and dopa melanins, the results indicate a close similarity in the groups identifiable by the IR spectra. The compositions of C, H, N, S, and O in these melanins were determined. Red hair melanin contained more S than black hair melanin; dopa melanin did not contain any S. Black and red hair melanins oxidized NADH at approximately the same rate. Ultraviolet irradiation increased the oxidation of NADH by red hair melanin to a greater extent than that by black hair melanin. These results show that although there are general similarities, there are significant differences in the physical and chemical properties of melanins isolated from black and red hair.
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    The color variants of mammalian hair, including spotting and albinism, are the result of melanocyte activity and have been shown to be determined by the action of multiple genes, some of which operate through the milieu in which the pigment cell resides; others appear to act intracellularly to control the type of melanogenesis. Although there has been much descriptive work on the mode of action of these genes, it has only been with the recent advances in the chemistry and molecular biology of melanin pigmentation that some progress is being made in understanding the nature and origin of hair color. It is the purpose of this article to provide an integrated overview of the major advances so made and to draw attention to certain peculiarities of the melanization processes of hair with respect to those underlying skin pigmentation. Key words: melanins, melanocytes, melanogenesis, hair.
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    The melanocortin 1 receptor, a seven pass transmembrane G protein coupled receptor, is a key control point in melanogenesis. Loss-of-function mutations at the MC1R are associated with a switch from eumelanin to phaeomelanin production, resulting in a red or yellow coat colour. Activating mutations, in animals at least, lead to enhanced eumelanin synthesis. In man, a number of loss-of-function mutations in the MC1R have been described. The majority of red-heads (red-haired persons) are compound heterozygotes or homozygotes for up to five frequent loss-of-function mutations. A minority of redheads are, however, only heterozygote. The MC1R is, therefore, a major determinant of sun sensitivity and a genetic risk factor for melanoma and non-melanoma skin cancer. Recent work suggests that the MC1R also shows a clear heterozygote effect on skin type, with up to 30% of the population harbouring loss-of-function mutations. Activating mutations of the MC1R in man have not been described. The MC1R is particularly informative and a tractable gene for studies of human evolution and migration. In particular, study of the MC1R may provide insights into the lightening of skin colour observed in most European populations. The world wide pattern of MC1R diversity is compatible with functional constraint operating in Africa, whereas the greater allelic diversity seen in non-African populations is consistent with neutral predictions rather than selection. Whether this conclusion is as a result of weakness in the statistical testing procedures applied, or whether it will be seen in other pigment genes will be of great interest for studies of human skin colour evolution.
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    The visual appearance of humans derives predominantly from their skin and hair color. The phylogenetical pathway underling this phenomenon is called melanogenesis and results in the production of melanin pigments in neural crest-derived melanocytes, followed by its transfer to epithelial cells. While melanin from epidermal melanocytes clearly protects human skin by screening harmful ultraviolet radiation, the biologic value of hair pigmentation is less clear. In addition to important roles in social/sexual communication, one potential benefit of pigmented scalp hair in humans may be the rapid excretion of heavy metals, chemicals, toxins from the body by their selective binding to melanin.
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    The biological importance and/or significance of human hair colour is unknown even though greying is obviously associated with ageing. In order to further characterise hair pigmentation in relation with hair growth variables we evaluated 3 scalp sites (top of the head (T): left and right and occipital(O)) in 12 untreated menopausal women (age range: 49-66 years: average 59.63 +/- 5.66) who presented complaining of hair loss and/or diffuse alopecia. Controls were 12 non menopausal sexually mature woman (7 age range 15-21 and 5 age range 38-48) not complaining of hair loss. One hair sample (whenever possible n = 60) was taken one month after clipping from T and O on each person; menopausal women were sampled twice. The following measures were performed with a light microscope: diameter (average min-max., microm), medulla (0% = absent to 100% = fully developed) and linear hair growth rate (mm/day). The hairs were categorised as pigmented (P) or non-pigmented (white, W) as compared with a black and white reference card. A total of 3343 hairs were analysed with 2-factor analysis of variance (ANOVA). A global comparison (all hairs) showed that the average diameter of W hair (67.68 microm) exceeded that of P hair (57.41 microm) (p = 0.0001) and this was maintained on all 3 scalp sites. In addition, the medulla of W hair (23.91%) appeared more developed than the medulla of P hair (12.21%) (p = 0.0001) and was more expressed in W T hairs as compared with W O hairs (p = 0.0325). There was also a significant interaction between site and pigmentation (p = 0.0074). Growth rate of W hairs (0.38 mm/d) was higher than that of P hairs (0.35 mm/d) (p = 0.0001) and there was a significant variation according to scalp sites (p = 0.0001). There was also a significant interaction between site and pigmentation (p = 0.0062) with the following rank order: O W (0.40 mm/d), T W (0.37 mm/d), O P (0.37 mm/d) and T P (0.34 mm/d). Subgroups of W and P of paired thickness in the range of 50 to 80 pm consistently showed a 10% faster growth rate of W. Previous studies have shown that growth rate and diameter declines in age and alopecia i.e. in hair thinning. Our data shows that the reduced growth rate of terminal hairs is in fact limited to the pigmented hairs. The mechanisms by which white hairs are spared these ageing changes are not yet understood. Less pigmented hairs are usually undetected by photo- graphic techniques used for drug trials. The potential role of drug induced modifications of hair pigmentation should be taken into account during the interpretation of efficacy except if contrast-enhancement has been applied.
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    Although hair greying is a very common phenomenon characterized by loss of pigment in the hair shaft, the events that cause and control natural hair whitening with age in humans are still unclear. To decipher the origin of natural hair whitening. Human hair melanocytes were immunohistochemically characterized at different stages of whitening. Loss of hair shaft melanin was found to be associated with a decrease in both bulb melanin content and bulb melanocyte population. Although few melanocytes were present in the bulbs of grey hair, they still expressed tyrosinase and tyrosinase-related protein-1, synthesized and transferred melanins to cortical keratinocytes as seen by the presence of melanin granules. In white hair bulbs, no melanocytes could be detected either with pMel-17 or vimentin labelling. Pigmented hair follicles are known to contain inactive melanocytes in the outer root sheath (ORS), and grey and white hairs were also found to contain some of these quiescent melanocytes. However, their population was decreased compared with pigmented hair follicles, ranging from small to nil. This depletion of melanocytes in the different areas of white hairs was detected throughout the hair cycle, namely at telogen and early anagen stages. In contrast, the infundibulum and sebaceous gland of both pigmented and white hairs showed a similar distribution of melanocytes. Furthermore, other distinct cell populations located in the ORS, namely putative stem cells, Merkel cells and Langerhans cells were equivalently identified in pigmented and white hairs. Thus, hair greying appears to be a consequence of an overall and specific depletion of bulb and ORS melanocytes of human hair.
  • Article
    Skin and hair colour mostly depend on the activity of melanogenic melanocytes. Numerous proteins involved in melanocyte function have been identified including pMel-17, Mitf-M, Sox10, tyrosinase, tyrosinase related proteins-1 (TRP-1) and -2 (TRP-2). In the hair, melanogenic activity occurs only during the anagen phase of the hair cycle. In order to evaluate the implications of some known melanogenic proteins in human hair pigmentation, we performed immunohistochemical studies to reveal the expression of pMel-17, Mitf-M, tyrosinase, TRP-1 and TRP-2 in active bulb melanocytes of eumelanic brown and black anagen hairs of different ethnic origins, e.g. brown Caucasian, black Asian and African hairs. The labelling was compared with that observed in Caucasian and African scalp epidermis (interfollicular epidermis) melanocytes. We found that while pMel-17, TRP-1 and TRP-2 were expressed in epidermal melanocytes irrespective of ethnic origin and melanin content of the scalp epidermis, Mitf-M and tyrosinase expression were clearly evidenced only in pigmented epidermis, e.g. African scalps. Regarding human hair, pMel-17, Mitf-M, tyrosinase and TRP-1 were detected in a similar manner in active bulb melanocytes of brown and black hairs. In contrast and unexpectedly, TRP-2 could not be detected in hair bulb melanocytes, whatever the hair colour and ethnic origin. The lack of TRP-2 was further confirmed by western blot analyses. Reverse transcriptase-polymerase chain reaction (RT-PCR) performed on hair bulb mRNA demonstrated that Mitf-M, tyrosinase and TRP-1 amplimer signals were easily detected, whereas the TRP-2 amplimer signal was barely detectable. Furthermore Sox10 was not detected in hair bulb. Altogether our results suggest that the absence of detectable level of TRP-2 is due to transcriptional control in active melanocytes of human eumelanic hair bulbs. According to the absence of TRP-2 in melanin-producing melanocytes of brown and black hair bulbs, one must consider that eumelanogenesis as well as brown and black colour do not require TRP-2 expression in human hair.
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    Full-text available
    ACTH, adrenocartico trophic hormone; Eso, sombre; Etob, tobacco; Fk, forskolin; MC1r, melanocortin 1 receptor; Mitf-M, microphtalmia transcription factor-M; POMC, proopiomelanocortin;; α-MSH, α-melanocyte-stimulating hormone; TRP-1, tyrosinase-related protein-1; TRP-2, tyrosinase-related protein-2
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    TRP-2 (dopachrome tautomerase) is a melanogenic enzyme whose expression was recently reported to modulate melanocyte response to different cytotoxic events. Here we studied a possible role of TRP-2 in the oxidative stress response in the amelanotic WM35 melanoma cell line. Cell viability assays showed that TRP-2 overexpression in WM35 cells reduced their sensitivity to oxidative stress. Comet assays linked TRP-2 expression to DNA damage protection, and high-performance liquid chromotography-tandem mass spectrometry experiments showed an increase in intracellular glutathione in TRP-2-overexpressing cells. These effects were specifically reversed when TRP-2 was silenced by RNA interference. Nevertheless, these properties appeared to depend on a particular cell environment because expression of TRP-2 failed to rescue HEK epithelial cells exposed to similar treatments.