ArticleLiterature Review

Androgens and hair growth

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Abstract

Hair's importance in human communication means that abnormalities like excess hair in hirsutism or hair loss in alopecia cause psychological distress. Androgens are the main regulator of human hair follicles, changing small vellus follicles producing tiny, virtually invisible hairs into larger intermediate and terminal follicles making bigger, pigmented hairs. The response to androgens varies with the body site as it is specific to the hair follicle itself. Normally around puberty, androgens stimulate axillary and pubic hair in both sexes, plus the beard, etc. in men, while later they may also inhibit scalp hair growth causing androgenetic alopecia. Androgens act within the follicle to alter the mesenchyme-epithelial cell interactions, changing the length of time the hair is growing, the dermal papilla size and dermal papilla cell, keratinocyte and melanocyte activity. Greater understanding of the mechanisms of androgen action in follicles should improve therapies for poorly controlled hair disorders like hirsutism and alopecia.

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... There has been more than a century of research on fur and hair growth across Mammalia, e.g., [5][6][7][8][9][10][11], reviewed in [12]. Yet, the majority of this has work been focused on animals that grow and shed seasonal coats, and on hair loss. ...
... Hair or fur growth for animals with more continuously growing hair, such as primates, has been much more limited. There has been some work on humans, e.g., [12][13][14][15][16][17], but remarkably little attention has been paid to fur and hair growth in non-human primates. The few exceptions are a handful of studies by Uno and colleagues on stump-tailed macaques (Macaca speciosa) that were focused on alopecia [18][19][20], a study by Fourie and colleagues [3] that demonstrated considerable variability in fur and hair growth for a handful of captive individuals (N = 1-3) from a range of old-world monkey and ape species (Allen's swamp monkey, Allenopithecus nigroviridis; golden-bellied mangabey, Cercocebus chrysogaster; gelada baboon, Theropithecus gelada; western lowland gorilla, Gorilla gorilla; yellow-cheeked crested gibbon, Hylobates gabriellae; and Siamang, Symphalangus syndactylus), and a study by Pereira and colleagues [21] that demonstrated seasonal fur growth for captive ring-tailed lemurs (Lemur catta) and red-fronted brown lemurs (Eulemur fulvus rufus). ...
... Fur and hair growth is primarily regulated by hormones, but may also be affected by nutrition, and possibly shaving. Sex hormones (particularly androgens) and thyroid hormones (e.g., thyroxine) are the most important players [10,12,29,30]. Seasonal fluctuations in growth are most pronounced in mammals with seasonal coats, but have also been observed in humans [16,[31][32][33][34]. ...
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Researchers typically assume constant fur and hair growth for primates, but the few studies that have investigated growth explicitly suggest this may not be the case. Instead, growth may vary considerably among individuals and across seasons. One might expect this variability to be most pronounced for species that have seasonally variable activity patterns (e.g., Madagascar’s Cheiorogaleidae). In particular, dwarf lemurs (Cheirogaleus spp.) undergo considerable changes in their daily activity levels (torpor) in the austral fall, when nights get shorter. I monitored regrowth of shaved fur patches for eight adult captive fat-tailed dwarf lemurs (Cheirogaleus medius) and gray mouse lemurs (Microcebusmurinus) on a bi-weekly basis for 21 months in total. Regrowth varied considerably both within and among individuals. Overall, fur regrew in spurts and was faster for mouse lemurs (0–14 to 215–229 days) than dwarf lemurs (27–40 to 313–327 days). There were significant differences between species and an obvious influence of season for dwarf lemurs, but no clear influence of shave location, age, or sex. Similar trends have been previously reported for captive lemurids, suggesting that seasonal fur growth may be widespread across Lemuroidea. Researchers are cautioned against using primate fur or hair to investigate variables confounded by seasonality (such as diet and body condition) until patterns of growth are better understood.
... Sebaceous glands, hair follicles and many types of skin cells express AR and the enzyme 5α-reductase, which converts testosterone to its more potent form, DHT [2,21,23]. The dermal papilla in the center of the hair bulb is a principal site of androgen action and influences keratinocytes of the hair follicle through paracrine signaling, regulating the size, shape and color of the hair as well as its frequency of regeneration [21,[24][25][26]. Androgenic or antiandrogenic activity results in loss or growth of scalp hair, respectively [2,22,27]. ...
... The role of estrogens in hair growth is controversial and complex [6,20,24]. The increase in female pattern hair loss (FPHL) following menopause suggests that estrogen promotes hair growth, although high-quality data have not yet become available to confirm an association between hair loss and menopausal status [30]. ...
... Estrogen has been postulated to aid hair growth by extending the anagen phase of the hair growth cycle [32], during pregnancy, for example [6]. In the postpartum period, an increase in number of hairs in the telogen phase results in increased hair shedding [5,6,24]. Estrogen is presumed to be the principal hormone responsible for changes in hair cycling around pregnancy; however, the interference by other hormones (such as prolactin) cannot be excluded. ...
Article
Hormones have an intimate relationship with hair growth. Hormonal replacement therapy is used to treat menopausal symptoms and to provide protection from chronic diseases for which postmenopausal women may be at risk. Additionally, hormonal therapies are prescribed for contraception and treatment of acne. Considering the widespread use of such therapies, there is a demand for further understanding of their implications in hair disorders. This article reviews the specific properties of current estrogen- and progesterone-containing hormonal treatments and their implications for the patient with hair loss. The complexity of the task comes from the paucity of data and discrepancy in the literature on the effect of the specific hormonal-receptor activities.
... The key role of androgen and its converting enzyme 5-α-reductase which converts testosterone to the more active dihydrotestosterone has been well-documented (Lolli et al. 2017;Randall 2008;Inui and Itami 2013). The opposing role of androgen in the beard and scalp HF has also attracted some attention. ...
... The opposing role of androgen in the beard and scalp HF has also attracted some attention. It is believed that the local microenvironment including the receptors, hormone metabolism, and HF properties control the different responses: while the beard HFs are stimulated to grow and enlarge, the scalp HFs diminish in size (Lolli et al. 2017;Randall 2008;Inui and Itami 2013). The inhibitory factors downstream of hormone and 5-α-reductase include TGF-β1, TGF-β2, IL-6 and Dkk1 (Inui and Itami 2013), whereas WNT5A, WNT10B and BMP2 are suppressed (Leirós et al. 2017;Ceruti et al. 2021) (Fig. 2B). ...
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Hair growth and regeneration represents a remarkable example of stem cell function. Recent progress emphasizes the micro- and macro- environment that controls the regeneration process. There is a shift from a stem cell-centered view toward the various layers of regulatory mechanisms that control hair regeneration, which include local growth factors, immune and neuroendocrine signals, and dietary and environmental factors. This is better suited for clinical application in multiple forms of hair disorders: in male pattern hair loss, the stem cells are largely preserved, but androgen signaling diminishes hair growth; in alopecia areata, an immune attack is targeted toward the growing hair follicle without abrogating its regeneration capability. Genome-wide association studies further revealed the genetic bases of these disorders, although the precise pathological mechanisms of the identified loci remain largely unknown. By analyzing the dysregulation of hair regeneration under pathological conditions, we can better address the complex interactions among stem cells, the differentiated progeny, and mesenchymal components, and highlight the critical role of macroenvironment adjustment that is essential for hair growth and regeneration. The poly-genetic origin of these disorders makes the study of hair regeneration an interesting and challenging field.
... In humans, facial hair represents a potential target of sexual selection by female choice and male-male competition (Dixson et al., 2005;Grueter et al., 2015). Beards are strikingly sexually dimorphic, appearing first in late childhood, developing further under the actions of androgens during puberty, with full expression typically evident at young adulthood (Randall, 2008). While muscularity and masculine craniofacial shape require testosterone for their expression (Griggs et al., 1989;Whitehouse et al., 2015), facial hair develops as testosterone is converted into dihydrotestosterone via the enzyme 5-alpha reductase 2 (Randall, 2008). ...
... Beards are strikingly sexually dimorphic, appearing first in late childhood, developing further under the actions of androgens during puberty, with full expression typically evident at young adulthood (Randall, 2008). While muscularity and masculine craniofacial shape require testosterone for their expression (Griggs et al., 1989;Whitehouse et al., 2015), facial hair develops as testosterone is converted into dihydrotestosterone via the enzyme 5-alpha reductase 2 (Randall, 2008). How androgens exert effects on the density, patterning, and distribution of facial hair is genetically determined (Adhikari et al., 2016). ...
Article
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Objectives To test whether intra-sexual selection has influenced perceptions of male facial hair. We predicted that beards would increase the speed and accuracy of perceptions of angry but not happy facial expressions. We also predicted that bearded angry faces would receive the highest explicit ratings of masculinity and aggressiveness, whereas higher prosociality ratings would be ascribed to clean-shaven happy faces.MethodsA total of 106 participants, ranging from 17 to 59 years of age (M = 27.27, SD = 10.03); 59 were female and 47 were male (44.3%) completed an emotion categorization tasks and an explicit ratings task. Participants viewed faces of the same men when bearded, clean-shaven, and 10 days of natural growth (i.e. stubble) when posing angry and happy facial expressions.ResultsAngry facial expressions were categorised most rapidly and with the greatest accuracy on bearded faces, followed by faces with stubble then clean-shaven faces. Conversely, happy facial expressions were categorised most rapidly and with the greatest accuracy on clean-shaven faces, followed by stubbled faces then bearded faces. Irrespective of facial expression, full bearded faces received the highest ratings of masculinity followed by faces with stubble then clean-shaven faces. Aggressiveness ratings were highest for angry faces with full beards, followed by angry faces with stubble, with clean-shaven angry faces receiving the lowest ratings. In contrast to our prediction, bearded smiling faces were rated as significantly more prosocial than stubbled and clean-shaven smiling faces.Conclusions These findings contribute further evidence that men’s beardedness represents an intra-sexually selected badge of status that enhances nonverbal threat potentially by augmenting underlying masculine facial structures.
... An adult human male has on average 10,000-20,000 hair follicles on the face (Robertson, 1999), which makes the difference between the sexes visually salient and easy to recognize. Additionally, male facial hair length may play a role in communicating levels of masculinity, which is a measure of typically male sexual characteristics that are influenced by androgen levels (Penton-Voak et al., 2004;Randall, 2008). The presence of a beard can produce a more masculine appearance, as a beard augments jaw size (Dixson et al., , 2018 and the midface (Guthrie, 1970;Sherlock et al., 2017). ...
... Previous research has shown that testosterone affects the density and rate of beard growth (Chieffi, 1949;Randall, 2008;Thornton et al., 1993Thornton et al., , 1998. However, in this study, we found no relationship between beard length and levels of testosterone and self-reported dominance. ...
Article
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The male beard is one of the most visually salient and sexually dimorphic traits and a hypothesized potential marker of other traits, such as dominance, masculinity, social status, and self-confidence. However, as men can easily alter their facial hair, beards may provide unreliable information about the beard owner’s characteristics. Here, we examined whether beards are honest signals of biological (testosterone levels) and psychological (self-reported dominance) traits. Young (M = 21.29, SD = 1.54) and healthy men (N = 97) participated in the study. Their beards were measured directly (using digital calipers) and by self-report. Participants provided saliva samples before and after acute exercise (to assess their testosterone and cortisol levels) and reported their dominance on a 5-item scale. The results showed that beard length (directly measured and self-reported) was not related to testosterone levels or dominance; thus, no evidence was found to support the hypothesis that beards are honest (or dishonest) signals of the beard owners’ testosterone levels and dominance.
... Each hair strand belonging to a single individual was cut from the proximal to the distal ends based on their monthly tail-hair growth rate (assuming that each segment corresponds with the previous month) and stored separately in labeled tubes for further analyses. The hair growth rate may vary between seasons, age-classes, sexes, dietary habits, reproductive states, etc (Randall & Ebling, 1991;Rushton, 2002;Randall, 2008;Bertoli et al., 2020); however, for the current study the monthly growth rate was assumed to be uniform across the tail-hair and segments were prepared accordingly. Each hair segment, representing growth over 1-month, was then pulverized, using two-three beads (3.0 mm Zirconia beads, ZB-30, Tomy Seiko Co., LTD., Tokyo, Japan) and the crusher (MS-100, Tomy Seiko Co., LTD.), for 5 min (three times). ...
... Inter-individual variation was observed in the hair growth rate, but differences in growth rate between hairs within the same individual were minimal (except for Mito). Hair growth in humans and other animals has been shown to be greatly influenced by a variety of exogenous and endogenous factors including quality of diet (nutritional contents such as zinc and iron status - Rushton, 2002), seasonality (Randall & Ebling, 1991), environmental factors (temperature, pollution -Johnson, 1981;Horev, 2007), age and sex of an individual (Bertoli et al., 2020) and their physiological and reproductive states (Randall, 2008;Grymowicz et al., 2020). There is a paucity of scientific information on how these factors influence the hair growth rates in elephants. ...
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Background Assessment of physiological states by measuring biomarkers, such as cortisol, has significantly contributed to the monitoring of health, welfare and management of animals. Immunoreactive cortisol in hair (hC) has been used widely for deciphering ‘stressful’ past-events in various wild and captive animals. However, no such studies have been done in long-lived mammals. Methods In this first exploratory study in elephants, we assessed (i) tail-hair growth rate (TGR) and (ii) hC levels in tail-hair samples from six captive Asian elephants from two zoos in Japan for comparing hC levels with zoo-keepers’ records of distinct biological events over a c.0.5–2.0-year period. Tail-hair samples were cut into segments (based on monthly growth rate), pulverized or minced and a validated cortisol enzyme-immunoassay employed to measure hC levels. Results When the hC levels of all individuals were compared with the keepers’ records, a posteriori , most of the high hC levels were found to be associated with ‘stressful’ or distinct behavioural events such as pathological (anaemia, colic infection, skin infection, oral sores), psychosocial (reluctance in entering the enclosure, presence of a calf) and husbandry practice-related (contact trials/ space sharing) conditions, indicating that tail-hair indeed can be a potential ‘retrospective’ calendar of physiological health of an animal. Conclusions Our observations open up the possibility of using the tail-hair as an alternative matrix to reconstruct the physiological history of elephants.
... 6 The appearance of pubic hair and axillary hair, an indication of puberty, also relies on the secretion of androgens from adrenal gland, known as the adrenarche. 7 However, excessive androgen can cause follicular dysplasia, which may impair ovulation and would result in menstrual disorders. In addition, androgen is an important hormone for maintaining the female's sexual desire. ...
Article
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Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women at reproductive age. However, the underlying pathogenic mechanisms have not been completely understood. Hyperandrogenism is an important clinic feature in patients with PCOS, suggesting its pathologic role in the development and progression of PCOS. However, the actual role of androgen and the related signals in PCOS and PCOS‐related complications have not yet been clarified. In this review, we surveyed the origin and effects of androgen on PCOS and the related complications, highlighted the cellular signals affecting androgen synthesis and summarized the pathological processes caused by hyperandrogenism. Our review well reveals the important mechanisms referring the pathogenesis of PCOS and provides important clues to the clinic strategies in patients with PCOS.
... An important role in the development of AGA is attributed to androgen steroid hormones that act directly in the hair follicle and inhibit scalp hair growth but stimulate beard growth. This condition is known as the androgenic paradox [2]. Besides the decrease in the level of sex hormones, the incidence of AGA increases with age and by the age of 80, it can affect 90% of the European population [3]. ...
Article
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Androgenetic alopecia (AGA) is the most common variant of male pattern baldness in which occurrence and development of multiple genetic, hormonal, and metabolic factors are involved. We aimed to estimate plasma element content (Mg, Ca, Zn, Cu, Se, Fe), vitamin status (B12, D, E, and folic acid) in patients with AGA using direct colorimetric tests or atomic absorption spectrometry, and the influence of these parameters in the formation of various hair loss patterns. The study included 50 patients with I–IV stages of AGA divided into two groups with normal and high levels of dihydrotestosterone compared with 25 healthy individuals. The presence of two patterns of pathological hair loss in the androgen-dependent (parietal) and androgen-independent (occipital) areas of the scalp was confirmed. It was shown that all patients with AGA have a deficiency of elements (Zn, Cu, Mg, Se) and vitamins (B12, E, D, folic acid). However, the hair loss rate was not due to their content. А positive interrelation between quantitative trichogram parameters in the occipital region and iron metabolism in pairs “hair density vs Fe” and “hair diameter vs ferritin” was shown. In turn, in the parietal region, an inverse correlation of hair diameter with plasma Cu level was found, the most pronouncing in patients with high levels of dihydrotestosterone. The obtained results indicate the importance of multiple micronutrient deficiencies in the AGA occurrence accompanied by the existence of two different hair loss patterns, differently related to the content of certain trace elements and androgens in the blood.
... Growth factors in hair growth, e.g., IGF-1, have been reported as important growth factors involved in hair growth and regulation by promoting the growth of epithelial cells in culture, increasing the tissue length of hair follicles, and acting as an important factor promoting hair growth (Itami et al., 1995;Hibino and Nishiyama, 2004). IGF-1 is involved in the increased expression by androgenic hormones and the action of testosterone on the hair, and it is known to play an important role in the mechanism of action that causes androgen-dependent alopecia (Price, 1999;Randall, 2008). ...
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Alnus sibirica Fisch. ex Turcz (ASFT), belonging to the family of Betulaceae, grows naturally in Asia, Europe, and America. The aims of this study are determining the efficacy of various biomarkers related to hair loss, evaluated by extracting the branch with 60% alcohol, and purely separating diarylheptanoid oregonin, an indicator and active substance, from 60% alcohol extract of the tree. To determine the preventive effects on hair loss, we investigated the anti-oxidative and anti-apoptotic effects on hydrogen peroxide-induced cytotoxicity on human hair dermal papilla cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Western blotting analysis for proving of apoptosis-related marker alteration, respectively. Moreover, we examined the ameliorative effects of 60% alcohol extract of the tree and oregonin against changes of oxidative stress-induced cytokine and testosterone-induced dihydrotestosterone production as crucial pathways of the hair loss mechanism. These results suggest that 60% alcohol extract of the tree and oregonin were available as novel natural materials for maintaining hair health in mammals.
... Some possible reasons for the inconsistent results of latanoprost on eyelashes and eyebrows compared to the scalp hair, is their different growth patterns. These differences consist of androgen sensitivity, hair cycle duration, number of follicles, average growth rate, and anagen or telogen duration (29)(30)(31)(32)(33). Chemotherapy induced alopecia is also a major problem, and poses a great burden in cancer patients, with approximate incidence of 65% which represents a challenge especially in women and children. ...
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ABSTRACT Background: Alopecia is a common condition among males and females in all age groups. There are many treatment options with their own benefits and side effects. In some cases, the current treatments lack sufficient efficacy. Therefore, there is a need to probe for alternative treatments. Recently, latanoprost has been suggested as an effective therapeutic option for managing scalp baldness. Objectives : To review latanoprost effects in different types of scalp alopecia. Data sources: Scopus and Pubmed data-base Eligibility criteria and Methods: In this review, we included the studies evaluating effects of latanoprost in different types of scalp alopecia including androgenic alopecia and alopecia areata in the English literature. Results: There were promising results for latanoprost application in animal models of androgenic alopecia. Effects of latanoprost on human scalp alopecia were satisfying in mostof the studies. In alopecia areata of the eyelash, some studies observed remarkable improvement, while others didn’t notice significant changes. One study suggested that latanoprost could be used as an effective adjuvant therapy with corticosteroids in alopecia areata of the scalp. Conclusion : It seems that latanoprost can be an efficient agent in the treatment of alopecia areata of scalp. Key words: Prostaglandin F, Latanoprost, Alopecia areata, Androgenic alopecia, Prostaglandin analog, Bimatoprost, Alopecia, Review
... Hair growth stimulants (hair tonic) are preparations that contain ingredients needed by hair, hair roots and scalp [1,2]. Currently, hair tonic preparations are widely available in the market both from chemicals and herbal ingredients [8,9]. ...
Article
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Objective: The purpose of this study was to determine the physical stability and effectiveness of hair growth in hair tonic preparations containing ethanol extract of clove leaves (Syzygium aromaticum) with a concentration variation of 5, 10, and 15%. Methods: Formulations were evaluated, including organoleptic observation, pH checking, and preparation stability tests using the Climatic Chamber. The effectiveness of clove leaf extract as a hair tonic was tested by looking at hair growth in test animals. Results: The results showed that the preparation was stable at high temperatures (40±2 °C) where the odor, color, clarity, and pH remained constant. Effectiveness test on rabbit hair growth showed significantly different results after measuring hair growth on the 21st day, where the results were 11.83+0.06 mm for positive control, 1.71+0.06 mm as blank, 1.69+0.06 mm for the group without treatment, and successively the results of the group given clove leaf extract 5, 10, and 15% were 4.00+0.06; 4.80+0.06; and 5.46+0.08 mm. Conclusion: Hair tonics containing clove ethanol extract can increase rabbit hair growth.
... [4][5][6][7][8][9] Serum free androgens have been thought to play an important part in the etiopathogenesis of AGA, which can bind to androgen receptors on the scalp to micronize hair follicles leading to hair loss. 10 It has been reported that serum-free androgens may stimulate vascular smooth muscle cells (VSMC) proliferation to promote atherosclerosis and cause vasoconstriction leading to hypertension. 11 Insulin resistance, as a CAD risk factor, can aggravate AGA, which may explain the positive correlation between AGA and CAD. ...
Article
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Purpose: This research aimed to investigate the correlation between androgenic alopecia (AGA) and coronary artery disease (CAD) and analyze its value in predicting the severity of coronary atherosclerosis in the Han Chinese male population. Patients and methods: A total of 402 Han Chinese male patients aged 28-75 years were enrolled and performed coronary angiography (CAG) after admission. According to the BASP classification, the participants were divided into mild, moderate and severe AGA. CAD was determined via CAG and defined as stenosis of ≥50% in at least one major coronary artery, and the Gensini score was calculated to evaluate the severity of coronary atherosclerosis. Results: In this study, CAD status (P = 0.002), dyslipidemia status (P = 0.002), age (P = 0.003) and coronary atherosclerosis severity (P < 0.001) were different in patients with different levels of AGA. Multivariate logistic regression analysis revealed that severe AGA was independently correlated to CAD risk (OR, 2.111; 95% CI 1.152 to 3.870, P = 0.016), while the relative CAD risk of early-onset AGA was 2.292 (OR, 2.292; 95% CI 1.132 to 4.640, P = 0.021). AGA status (OR, 2.247; 95% CI 1.396 to 3.617, P = 0.001), severe AGA (OR, 2.360; 95% CI 1.506 to 3.699, P < 0.001) and early-onset AGA (OR, 3.474; 95% CI 2.069 to 5.832, P < 0.001) were all independently associated with the severity of coronary atherosclerosis. The area under the receiver operating characteristic (ROC) curve plotted using severe AGA was 0.601, which is predictive of severe coronary atherosclerosis. Moreover, the presence of severe AGA increases the risk of developing CAD associated with obesity (SI = 1.663, SIM = 1.222, AP = 0.289), diabetes (SI = 2.239, SIM = 1.149, AP = 0.503) and dyslipidemia (SI = 1.062, SIM = 0.646, AP = 0.045). Conclusion: This study suggested that AGA is independently associated with CAD in a Han Chinese male population. AGA may be a simple and feasible method for screening CAD and indicative of the severity of coronary atherosclerosis.
... There have also been breakthroughs in the treatment of androgenic alopecia. The transition of some terminal hairs into vellus hairs is an androgen dependent secondary sexual characteristic but vice versa of that phenomenon cause baldness [55]. ...
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Beauty is a prime concern of life. The standards of beauty varies from place to place but healthy skin and lustrous hair are focused point of concern in poetries and also applicable in daily life. So this review is based on various disorders of skin such as hyperpigmentation, wrinkle, leucoderma, dark circles, acne etc. and various disorders of hair such as alopecia, dandruff, seborrhea which give rise to ugly and aged appearance and the natural remedies for these disorders as they do not have side effects and are economic, biocompatible and ecofriendly.
... Neave & Shields, 2008;Wogalter & Hosie, 1991). Beardedness is an obvious biological marker of sexual maturity (Alwaleedi, 2015;Randall, 2008). However, it is generally unrelated to health and provides little survival advantage . ...
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Researchers have found that men's facial hair may have certain signaling functions connected with intrasexual competition and intersexual attractiveness. The interesting issue is whether men's and women's preferences for men's facial hair may be considered a reflection of their intuitive knowledge about these functions. The aim of the presented studies was to analyze women's and men's preferences regarding men's facial hair using questions with a dichotomous answer format (Study 1 and Study 2) and pictorial stimuli (Study 2). In both studies, women were asked to indicate their preferences for men's facial hair. Men were asked to report preferences for facial hair in themselves and in other men, as well as to report their actual appearance of facial hair. The results showed that women's preferences for men's facial hair were ambiguous, while men preferred facial hair for themselves and had a lower inclination to prefer facial hair in other men. It suggests that men may be aware of some aspects of signaling functions of facial hair, especially these connected with intrasexual competition.
... Pattern baldness or hair loss/absence of hair, which is most noticeable on the scalp, is due to a combination of genetic and hormonal effect and therefore is regarded as a sex-influenced trait (Randall, 1994;Burns and Bottino, 1988). Differences exist in the amount and distribution of hair loss between genders, races and ethnic groups of people (Nalluri and Harries, 2016). ...
Article
Prevalence of some common human traits viz., body weight, height and body mass index (BMI), pattern baldness, body hair, chin, colour blindness, cheek dimples, earlobes, length of index finger, lips, nose, polydactyly, tongue and widow’s peak, and ABO blood groups along with their Rh-D antigen, were recorded and analyzed from 500 male and 1000 female students of the Rajshahi University (RU) Campus. Results showed that body weights of the male students (66.42±8.92 kg) were significantly higher (t= 35.14; P<0.001) than those of the female students (51.64±6.97 kg). The differences in BMI between males (23.32±3.26) and females (20.85±2.63), as expected, were also highly significant (t= 15.79; P<0.001) and notably, some of the female students were underweight (BMI< 18.5). No female had baldness compared to 15.8% bald males. Sparse body hair was prevalent over the dense body hair in both genders. The females had much higher smooth chin (89.6%) than the males (58.0%) but the males had much higher cleft chin (42.0%) compared to the females (10.4%). No female was colourblind whereas 7.4% males were colourblind. Absence of dimples was recorded in 92.4% males and 85.7% females. Attached earlobes were higher than the free earlobes in both sexes. Compared to the length of the ring finger, shorter index finger was prevalent both in males (85.4%) and females (68.6%). Frequencies of the broad lips in males and females were 53.4% and 58.6%, respectively. Females dominated large and broad noses (76.1%) in comparison with their male counterparts (61.4%). Polydactyly was a rare trait in the Campus, where only 2.2% males and 0.2% females had extra digits in their hands or feet. Tongue rollers (53.8%) outnumbered the tongue folders in males, but tongue folders (54.4%) outnumbered the tongue rollers in females. Males with widow’s peak were higher (25.8%) than that in the females (19.0). Blood groups in the males and females were in the order: B (32.0) > O (29.8) > A (22.4) > AB (15.8) and O (34.8) > B (34.4) > A (21.9) > AB (8.9), respectively. As a whole, 85.4% males and 98.0% females were Rh-positive where the blood group phenotypes did not affect body weight, height and BMI of the subjects (r=0.012; P=0.63). The relevance of these findings to the physical, physiological, social and clinical well-being of the humans has been discussed. Bangladesh J. Zool. 49 (2): 215-228, 2021
... Androgens play a pivotal role in the development of FAGA. The dermal papilla of the pilosebaceous unit is able to synthesize and metabolize a wide range of androgens, with subsequent alteration of soluble factors regulating the growth and activity of hair follicles keratinocytes [12,13]. ...
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Background: female androgenetic alopecia (FAGA) is a common cause of non-scarring alopecia in women, affecting approximately 40% of women by age 50, bearing a significant psychosocial burden on affected patients. Platelet-rich plasma (PRP) has been widely investigated as a potential effective treatment for several dermatological conditions, including male androgenetic alopecia (MAGA). However, few studies have been conducted focusing on the use of PRP in FAGA. The aim of this review was to identify reports that investigated the use of PRP for the treatment of FAGA. Methods: Electronic databases of MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) from inception to September 2020 have been searched using different combinations of the following terms: “androgenetic alopecia,” “FAGA,” “female pattern hair loss,” “platelet-rich fibrin,” “platelet-rich plasma,” and “PRP”. Results and conclusions: Eight (n = 8) clinical studies consistent with our research were identified. A total of 197 subjects has been enrolled in the included studies. All of them were adult female patients (mean age: 38.9) affected by female pattern hair loss. PRP is a well-tolerated procedure which showed promising results in males-only and mixed populations of AGA patients. PRP showed to produce high levels of satisfaction and improvement in the quality of life in patients affected by FAGA. In the light of this evidence, PRP may be proposed in patients who did not respond or did not tolerate topical minoxidil, as well as in combination with topical and oral treatments.
... Pharmaceutics 2020, 12, 0994 2 of 20 individuals, they reverse the transformation of large, deep follicles producing long, often heavily pigmented terminal scalp hairs to miniaturised vellus follicles forming tiny, almost invisible hairs [4]. Testosterone, a key androgen, is converted to its potent form, dihydrotestosterone (DHT), by the 5α-reductase enzyme, which appears to have a higher activity on the balding scalp compared to the non-balding scalp [5]. ...
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Dutasteride, licensed as an oral medicine for the treatment of benign prostatic hypoplasia, has been investigated as a treatment for androgenic alopecia. In this study, the potential for dustasteride to be delivered topically in order to reduce systemic exposure, irritation of the skin, and also cytotoxicity was explored. Chitosan oligomer (CSO) was successfully synthesised with lauric acid as a coating for a dutasteride-loaded nanostructured lipid carriers (DST-NLCs) system. DST-NLCs were prepared using a combination of melt-dispersion and ultrasonication. These negatively charged NLCs (−18.0 mV) had a mean particle size of ~184 nm, which was not significantly increased (p > 0.05) when coated with lauric acid-chitosan oligomer (CSO-LA), whilst the surface charge changed to positive (+24.8 mV). The entrapment efficiency of DST-NLCs was 97%, and coated and uncoated preparations were physically stable for up to 180 days at 4–8 °C. The drug release was slower from DST-NLCs coated with CSO-LA than from uncoated NLCs, with no detectable drug permeation through full-thickness pig ear skin from either preparation. Considering the cytotoxicity, the IC50 values for the DST-NLCs, coated and uncoated with CSO-LA were greater than for dutasteride alone (p < 0.05). DST-NLCs and empty NLCs coated with CSO-LA at 25 µM increased the cell proliferation compared to the control, and no skin irritation was observed when the DST-NLC formulations were tested using EpiDerm™. The cell and skin uptake studies of coated and uncoated NLCs incorporating the fluorescent marker Coumarin-6 showed the time-dependent uptake of Coumarin-6. Overall, the findings suggest that DST-NLCs coated with CSO-LA represent a promising formulation strategy for dutasteride delivery for the treatment of androgenic alopecia, with a reduced cytotoxicity compared to that of the drug alone and lower irritancy than an ethanolic solution of dutasteride
... Most of our adult bodies are covered in vellus hairs that are short, thin, and relatively unpigmented. Certain parts of our bodies, such as the head, face, armpit, and pubic area, have collections of terminal hairs that are long, coarse, pigmented and under the influence of particular hormones (e.g., androgens; Randall, 2008). The evolution of human "hairlessness" has likely provided some important survival benefits, perhaps in terms of more efficient thermoregulation and a greater defense against ectoparasites, such as lice (i.e., the ectoparasite avoidance hypothesis; Rantala, 2007;Ruxton & Wilkinson, 2011;Sandel, 2013). ...
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Researchers have highlighted numerous sociocultural factors that have been shown to underpin human appearance enhancement practices, including the influence of peers, family, the media, and sexual objectification. Fewer scholars have approached appearance enhancement from an evolutionary perspective or considered how sociocultural factors interact with evolved psychology to produce appearance enhancement behavior. Following others, we argue that evidence from the field of evolutionary psychology can complement existing sociocultural models by yielding unique insight into the historical and cross-cultural ubiquity of competition over aspects of physical appearance to embody what is desired by potential mates. An evolutionary lens can help to make sense of reliable sex and individual differences that impact appearance enhancement, as well as the context-dependent nature of putative adaptations that function to increase physical attractiveness. In the current review, appearance enhancement is described as a self-promotion strategy used to enhance reproductive success by rendering oneself more attractive than rivals to mates, thereby increasing one’s mate value. The varied ways in which humans enhance their appearance are described, as well as the divergent tactics used by women and men to augment their appearance, which correspond to the preferences of opposite-sex mates in a heterosexual context. Evolutionarily relevant individual differences and contextual factors that vary predictably with appearance enhancement behavior are also discussed. The complementarity of sociocultural and evolutionary perspectives is emphasized and recommended avenues for future interdisciplinary research are provided for scholars interested in studying appearance enhancement behavior.
... Contrary to the "naked ape" image, the key functions of human hair are protection, social communication, and signaling, with hair having high significance for both males and females across a wide range of cultures (Randall, 2008) in both social and psychological experiences (Henss, 2001). Hence, despite hair's primal function as protection (e.g., camouflage, insulation), its importance as a form of social communication or status has increased over time. ...
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How are masculine‐looking politicians perceived by voters? Are these judgments accurate? We asked Australian survey participants to rate images of unknown‐to‐them Swiss politicians. We find that politicians with prominent markers of masculinity (including facial hair, baldness, and higher facial width‐to‐height ratio) are perceived as less honest and competent. To determine whether these perceptions correlate with political behavior, we exploit two unique features of Swiss politics. First, to check for politician–voter congruence, we match each politician's voting record to that of their constituents on identically worded legislative proposals. We find that bearded politicians are less likely to behave according to constituents' preferences. Second, by exploiting the mandatory disclosure of lobby group affiliations, we show that bearded politicians are less likely to be captured by interest groups. Our results suggest that more masculine‐looking politicians are recognized by both voters and lobby groups as less amenable to being controlled.
... contains supplementary material, which is available to authorized users. genetically determined androgen-dependent secondary sexual characteristic (Randall 2008). Experimental studies report that facial hair augments ratings of men's age (Neave and Shields 2008), masculinity (Addison 1989;Dixson and Brooks 2013) social status (Dixson and Vasey 2012), physical dominance (Gray et al. 2020;Saxton et al., 2016) and aggressiveness (Geniole and McCormick 2015;Muscarella and Cunningham 1996;Nelson et al. 2019). ...
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Objectives To test whether cross-cultural variation in men’s facial hair conforms to patterns predicted by processes of inter-sexual and intra-sexual selection.Methods Data were taken from the PEW Research Center’s World’s Muslims’ project that collected information from 14,032 men from 25 countries. An Independent Factor Analysis was used to analyse how suites of demographic factors predict men’s beardedness.ResultsAnalyses replicated those from past research using the PEW data, showing that beardedness was more frequent under prevailing conditions of lower health and higher economic disparity.Conclusions These findings contribute to evidence that men’s decision to augment their masculinity via full beardedness occurs under conditions characterised by stronger inter-sexual and intra-sexual selection.
... Hair loss is a disorder in which the amount of hair is less or more than normal with or without visible thinning. Normally 80-120 strands of hair are shed per day 5,6 . The normal number of hair follicles on the head is around 100,000, and it is called an abnormality if the number reaches 50% which means about 50,000 strands. ...
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Hair loss is an unavoidable process, as the age increase, the rate of hair growth also slows down. Hair loss is caused by many factors and occur in different areas of body. Since hair become one of the major aspect for women beauty, hair loss will become a serious problem if it is not solved. Many plants or their extracts have been used to reduce hair loss. The leaves of sea hibiscus (Hibiscus tiliaceus L.) have been known empirically to promote hair growth and prevent hair loss. The leaves contain saponin, flavonoid, and also polyphenol compounds. The purpose of this study was to formulate sea hibiscus leaf extract into hair tonic preparations and evaluate the activity in triggering hair growth. In this research, tested animals were divided into 5 groups: F0 (blank) as a negative control, F1 (20%), FII (25%), FIII (30%) extract of sea hibiscus leaves and minoxidil as positive control. All preparations made were kept in room temperature for 12 weeks and the pH value test was carried out in first, fourth, eighth and twelfth week. The hair growth activity was done by applying hair tonic to the guinea pig and hair was randomly plucked from test area measuring hair length using calliper on the 7th, 14th, 21st days. On the 21st day, hair tonic of 30% sea hibiscus leaf extract showed a great activity on the growth of hair length with an average of 17.2633 mm and weighed an average of 0.145g, with a significant difference compared to another formula (p < 0.05). Keywords: Hair tonic, Hibiscus tiliaceus, Sea Hibiscus Leaves
... Incidence of hair loss/thinning increases with age (senescent alopecia) (Whiting, 2011) and in patterned hair loss, often related to hormonal responses. In men, androgenetic alopecia causes miniaturization of frontotemporal and vertex follicles (Randall, 2008), while FPHL presents as diffuse thinning, with onset commonly associated with menopause (Chen et al., 2010;Thornton, 2005) when circulating estrogen drops as ovarian function ceases, accelerating age-related skin deterioration (Stevenson and Thornton, 2007;Thornton, 2013Thornton, , 2002. ...
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In women, ageing leads to reduced hair density and thinner fibers and can result in female pattern hair loss (FPHL). However, the impact of the ageing dermal environment on female scalp hair follicles (HFs) remains unclear. Here we document in situ changes in 22 women (19-81yrs), and in primary cultures of dermal fibroblast (DF) and dermal sheath (DS) cells. In situ, the papillary/reticular boundary was indistinguishable in young scalp, but prominent over 40yrs, accompanied by reduced podoplanin (PDPN) expression, increased versican (VCAN) expression, and changes in collagen organisation. HFs were shorter, not reaching the adipose layer. Hyaluronic acid synthase 2 (HAS2) was highly expressed, while matrix metalloproteinase-1 (MMP1) was elevated in the DP and DS in situ. Primary DF cultures confirmed MMP1 increased with age, while in DS cells, HAS2 and PDPN increased and α-smooth muscle actin (αSMA) decreased. Both exhibited increased cartilage oligomeric protein (COMP) expression. Proteomics revealed an increase in DS proteins in the DF secretome with age. In summary, ageing female scalp shows striking structural and biological changes in the HF environment that may impact hair growth.
... In addition to hair type/shape, another reason for racial group differences in cortisol concentrations may be variability in rates of growth by season and hair type, hair density, or hair loss (Loussouarn et al., 2016;Randall, 1994). Studies have found group differences in hair growth depending on geographic origins and density variability within racial groups (Loussouarn et al., 2016). ...
Article
The biomarker cortisol assesses the impact of biopsychosocial stressors that activate the stress response system. Hair has emerged as a valid and non-invasive means of gauging cumulative cortisol deposited over month-long periods of time. Established protocols for the extraction of hair cortisol are being validated and refined in humans, yet methodological information about hair characteristics on cortisol remains limited. In addition to external hair exposures (e.g. dye, time spent outside), we examined hair categorization or type (e.g. kinky, straight) by extending a hair typing methodology for scientific use that is currently popular among hair care professionals. We then examined the interaction between hair type and race on cortisol levels with a hair questionnaire. Three studies were pooled to investigate how sample weight, hair type, race, heat exposures, and hair treatments impacted cumulative hair cortisol concentrations. Study 1 consisted of Adult Kenyan Medical Workers (N=44); Study 2 Mexican and Mexican Americans (N=106); and Study 3 American Youth (N=107). We found significantly higher cortisol in 5 mg of hair when compared to larger sample weights, and higher cortisol in those who spent more time outdoors. Cortisol concentrations differed between racial groups and varied by hair type; moreover, there were directional differences in cumulative cortisol from straighter to curlier hair types which depended on racial group. In addition to demonstrating the impact of relatively novel control factors like hair sample weight, outdoor exposure, and hair type, the present study illustrates the importance of disentangling hair type and race to understand variability in cumulative hair cortisol. These influences should be included in future studies that measure hair cortisol.
... The hairy growth on the face caused by reasons including testosterone and genetics, a sign of biological maturity (Moller, 1987), also has destabilising psychological consequences. The hairy growth on the face indicates the arrival of adulthood and marks sexual maturity (Randall, 2008). Although beard is a dimorphic secondary trait but it was quite surprising to find its missing connection with sexual maturity rather its meaning predominantly revolved around socio-cultural aspects. ...
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The trend of wearing a bearded look has become a vogue. This study sought to explore the underlying reasons and reconcile contraction between expressed superficiality and practised profundity of growing facial hair from a psycho-socio-cultural perspective.
... In the circulatory system, lion's share of T and DHT is bound to transport protein while only 1% is free, which is the biologically active form [80]. The androgens have important physiological roles including, enhancement of bone growth, calcium deposition, muscle mass buildup, development of signs of puberty such as axillary and pubic hair growth, and maintenance of female sexual desire [81][82][83]. Serum levels of DHEAS, T, DHEA, and free T were known to be elevated in PCOS patients. Ovary thecal cells of PCOS women exhibited an upregulated messenger RNA (mRNA) level of steroidogenic acute regulatory (StAR), cytochrome P450 family 11 subfamily A member 1 (CYP11A), cytochrome P-450c17alpha (CYP17A1), and luteinizing hormone (LH) receptors when compared to normal cycling women [84]. ...
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Polycystic ovary syndrome (PCOS) is one of the most frequently observed endocrinopathies among women of reproductive age that redound to subfertility. The specific etiology of this heterogenic syndrome remains ambiguous. Metabolic complications, hormonal imbalance, deregulation in the immune system and their interrelationship make PCOS more complex. Hyperandrogenism and chronic low-grade inflammation modulate each other and enhance the self-perpetuation of PCOS. Even though there are many literature studies on PCOS and immune deregulation, this review focuses on the endocrine-immune nexus and how the altered endocrine system is embroiled in the immunopathology of PCOS.
... It should be noted thatandrogens are the main hormonal regulators of hair growth [10]. According to Sato et al. [11] minoxidil in human dermal cell culture is able to increase the activity of enzymes involved in androgen metabolism. ...
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The problem of alopecia, for treatment of which the use of over the counter lotions containing minoxidil is recommended, is paid considerable attention all over the world. The consumers rarely seek medical advice due to certain psychological barriers. Thus, it contributes to the uncontrolled use of the drugs, and fixation of their side effects becomes impossible. There are isolated reports on the effect of minoxidil containing lotions on male fertility. The Aim. To establish organometric parameters of testes and their paradidymis, functional parameters of spermatozoa in mature rats under topical exposure to a 10% minoxidil containing lotion. Methods. Analytical, toxicological, statistical. Results. It was established that under the conditions of 72-day percutaneous application of 10% minoxidil containing lotion some changes in the reproductive system organs can be observed, which are in particular a decrease in the mass of testes and epididymis, as well as a decrease in organs’ linear size. The total time of motor activity of gametes after exposure to a lotion containing 10% minoxidil has statistically significantly shortened, a 6-fold inhibition of the activity of redox processes occurred in the rats of the experimental group compared to the control one. Conclusions. Taking into consideration the obtained data and the uncontrolled and long-term use of 10% minoxidil containing lotions by men of reproductive age, an in-depth study of its gonadotoxic effects in experimental conditions in combination with epidemiological studies of the patients using these lotions is deemed necessary. Key Words: minoxidil, gonadotoxicity, mature rats.
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Steroidogenesis is a set of metabolic reactions where the enzymes play a key role to control the physiological levels of steroids. A deficiency in steroidogenesis induces an accumulation and/or insufficiency of steroids in human blood and can lead to different pathologies. This issue added to the low levels of steroids (pg mL⁻¹ to ng mL⁻¹) in this biofluid make of their determination an analytical challenge. In this research, we present a high-throughtput and fully automated method based on solid-phase extraction on-line coupled to liquid chromatography with tandem mass spectrometry detection (SPE–LC–MS/MS) to quantify estrogens (estrone and estradiol), androgens (testosterone, androstenedione, dihydrotestosterone and dehydroepiandrosterone), progestogens (progesterone, pregnenolone, 17-hydroxyprogesterone and 17-hydroxypregnenolone), glucocorticoids (21-hydroxyprogesterone, 11-deoxycortisol, cortisone, corticosterone and cortisol) and one mineralocorticoid (aldosterone) in human serum. The performance of the SPE step and the multiple reaction monitoring (MRM) mode allowed reaching a high sensitivity and selectivity levels without any derivatization reaction. The fragmentation mechanisms of the steroids were complementary studied by LC–MS/MS in high-resolution mode to confirm the MRM transitions. The method was characterized with two SPE sorbents with similar physico-chemical properties. Thus, limits of quantification were at pg mL⁻¹ levels, the variability was below 25% (except for pregnenolone and cortisone), and the accuracy, expressed as bias, was always within ±25%. The proposed method was tested in human serum from ten volunteers, who reported levels for the sixteen target steroids that were satisfactorily in agreement with the physiological ranges reported in the literature.
Article
Hirsutism is defined as the presence of terminal hair with male pattern distribution in women. While in the general population, hirsutism affects around 4–11% of women, it is the main manifestation of hyperandrogenism in women with polycystic ovary syndrome (PCOS), with a prevalence estimated at 65–75%. Hirsutism in PCOS is associated with both androgen excess and individual response of the pilosebaceous unit to androgens. The modified Ferriman–Gallwey (mFG) scoring system has been widely used in clinical practice to visually score excessive terminal hair, thus standardizing hirsutism evaluation and facilitating data comparison. Although a universal mFG score cutoff would be useful for comparisons, ethnic variations, as well as skin type and other factors, should be considered when evaluating hirsutism in distinct populations. In turn, androgen levels, measured by conventional techniques, have been shown to correlate poorly with the severity of hirsutism. Indeed, while most women with PCOS and hirsutism also have higher than reference values for serum androgen levels, some of them may not present with biochemical hyperandrogenism, representing a challenge to the diagnosis of PCOS. In this article, we critically review this not uncommon condition in women with PCOS presenting with hirsutism but normal androgen levels.
Chapter
Hair may vary considerably in length, width, quantity, and distribution of follicles depending on its type and location on the human body. The two main types of hair are terminal hair and vellus hair. Terminal hairs are normally thicker and longer, with hair shaft diameters greater than 0.06 mm and hair bulbs rooted deeply in the subcutaneous tissue. On the other hand, vellus hairs are usually only 1–2 mm in length and have thinner shafts measuring less than 0.03 mm in diameter. Their bulbs are located in the upper portion of the dermis, and they are characteristically more hypopigmented than the baseline hair color. Vellus hair is typically more noticeable on women and children because men tend to have more terminal body hair [1].
Article
This chapter focuses on the microscopical examination of hair in the forensic domain. It discusses the relevant biological aspects of hair to provide the necessary background information upon which forensic hair examinations are based. The chapter introduces the methodologies and techniques used by forensic hair examiners. It describes the basic chemistry and basic histology of hairs. Each individual hair progresses through a regular and predictable cycle. This cycle is classically described as having three major phases: anagen, catagen, and telogen. While a variety of methods can be used, forceps and tape lifts are the two most commonly employed techniques for collecting hairs. Most forensic hair cases involve the examination of human hair. Historically, the emphasis has been placed on human hair comparisons. The chapter provides general guidelines for the comparison of hairs. Finally, the interpretation and significance of the results obtained through a microscopical hair examination are considered.
Article
Androgenetic alopecia (AGA) is a common genetic disorder, and a X-chromosomal locus that contains the androgen receptor (AR) and ectodysplasin A2 receptor (EDA2R) genes represents a major susceptibility locus for AGA. In our previous study, we reported that ectodysplasin-A2 (EDA-A2) induces apoptosis in cultured human hair follicle (HF) cells and promotes the regression of HFs in mice. However, the role of the EDA-A2/EDA2R in AGA remains unknown, as the causative gene in this pathway has not yet been identified and potential functional connections between EDA-A2 signaling and the androgen pathway remain unclear. In this study, we investigated the expression of EDA2R in balding HFs and matched with non-balding HFs. The EDA2R level was upregulated in the balding dermal papilla (DP) cells compared with non-balding DP cells derived from patients with AGA. However, EDA2R was strongly expressed in both balding and non-balding outer root sheath (ORS) cells. We screened EDA-A2-regulated genes in balding DP cells and identified dickkopf 1 (DKK-1) as catagen inducer during the hair cycle. The mRNA and protein expression levels of DKK-1 were both upregulated by EDA-A2. In addition, DKK-1 expression was induced by EDA-A2 both in cultured human HFs and in mouse HFs. Moreover, the EDA-A2-induced apoptosis of DP and ORS cells was reversed by the antibody-mediated neutralization of DKK-1. Collectively, our data strongly suggest that EDA-A2 induces DKK-1 secretion and causes apoptosis in HFs by binding EDA2R, which is overexpressed in the bald scalp. EDA-A2/EDA2R signaling could inhibit hair growth through DKK-1 induction, and an inhibitor of EDA-A2/EDA2R signaling may be a promising agent for the treatment and prevention of AGA.
Chapter
Hyperandrogenism, defined as elevated circulating C19 androgen (dehydroepiandrosterone [DHEA], dehydroepiandrosterone sulfate [DHEAS], androstenedione, and testosterone) concentrations, presents with a variety of clinical and biochemical characteristics. Typically, in females, hyperandrogenism is due to increased adrenal and/or ovarian C19 steroid androgen production. Hyperandrogenism is often associated with an underlying endocrine disorder. Common presenting features in adolescent girls include hirsutism, severe acne that is unresponsive to topical medications, and irregular menses. Evaluation includes a thorough history and physical exam followed by laboratory studies to assess for elevated circulating androgens. Suspicion for polycystic ovary syndrome, disorders of steroidogenesis, or an androgen-secreting tumor should prompt referral to pediatric endocrinology for evaluation and management. Topical or cosmetic treatments may benefit some patients with familial isolated hirsutism and acne, a diagnosis of exclusion. Poor response to these treatments should prompt further evaluation to assess for hyperandrogenism with a specialist.
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Pattern Hair Loss (PHL) is a chronic regressive condition of the scalp, where follicular miniaturisation and decreased scalp hair coverage occurs in affected areas. In all PHL cases there is a measurable progressive shortening of the terminal hair growth duration, along with reduced linear growth rates. In both genders, PHL initially shows an increase in short telogen hairs ≤30mm in length, reflecting a cycle completion of under six months in affected terminal hair follicles. To understand the miniaturisation process, we re-examine the dynamics of miniaturisation and ask the question, ‘why do miniaturised hair follicles resist treatment?’ In the light of recent developments in relation to hair regeneration, we looked back in the older literature for helpful clues ‘lost to time’ and reprise a 1978 Hermann Pinkus observation of an array of elastin deposits beneath the dermal papilla following subsequent anagen/telogen transitions in male balding, originally described by Arao and Perkins who concluded that these changes provide a “morphologic marker of the entire biologic process in the balding scalp”. Thus, we have reviewed the role of the elastin-like bodies in hair pathology and we propose that alterations in elastin architecture may contribute to the failure of vellus-like hair reverting back to their terminal status and may indicate a new area for therapeutic intervention.
Chapter
Androgenetic Alopecia (AGA) is by far the most common cause of hair loss in men, and its high prevalence has been reported in detail for many decades [1]. Several different terms in international medical bibliography have been suggested by several authors, such as androgenic alopecia, male pattern baldness, androgen-dependent alopecia, common baldness, and genetic hair loss. However, the term “Androgenetic Alopecia” is considered the most appropriate since it summarizes the etiology of the condition, with the term “andro-” referring to the hormonal and “-genetic”, implying the inherited parameter of its pathogenesis.
Chapter
Introduction: The Dermal Papilla (DP) has been the focus of many studies regarding the hair follicle due to its critical role in morphogenesis, hair cycling, and de novo induction. These studies have led to the current ambition of harnessing DP cells to provide a clinical cell-based therapy which overcomes the major limitation in hair follicle transplantation, a lack of donor material. Methods: Revision of peer-reviewed published literature using different databases including Pubmed. Results: Early work using explanted DP demonstrated a capacity to induce de novo hair follicles at implantation sites. In order to overcome limited donor material, cells need to be expanded in vitro. However, DP cells lose their inductive potential when cultured. In order to address this issue, researchers have attempted to maintain, restore, and improve inductivity in a number of ways. The most successful of these studies to date have combined elements of the 3 pillars of Tissue Engineering: Cells, Signals and Scaffolds. Conclusions: In the past, most approaches have utilised single pillar approaches in order to improve DP inductivity with limited success. More recent bioengineered solutions which are carefully designed to factor all three pillars of tissue engineering are starting to show real promise. Challenges remain, largely surrounding the quality of induced hair follicles and the efficiency to which they are induced as well as time and cost to deliver these therapies. However, if these issues can be overcome, tissue engineered hair follicle restoration would present a significant step-change in hair follicle restoration.
Article
Background: Animal studies suggest that exposure to certain neonicotinoids may interfere with the normal function of endocrine system in mammals. However, evidence from human studies is limited. Objectives: This study conducted a cross-sectional analysis to examine urinary neonicotinoids concentrations in Chinese adolescents and its association with pubertal development. Methods: 774 urine samples from 439 boys (median age: 13.7 years; 25th-75th percentile: 12.7-14.5 years) and 335 girls (median age: 13.7 years; 25th-75th percentile: 12.7-14.5 years) were collected for determination of ten neonicotinoids (imidacloprid, nitenpyram, acetamiprid, thiacloprid, imidaclothiz, thiamethoxam, clothianidin, dinotefuran, flonicamid, sulfoxaflor) and one metabolite (N-desmethyl-acetamiprid). Urinary creatinine was detected for concentration adjustment. Pubertal development including pubic hair, axillary hair, genitalia (boys), testicular volume (boys) and breast (girls) assessed by Tanner stages and others (spermarche, facial hair for boys and menarche for girls) were obtained by physical examination and questionnaire. Logistic and bayesian kernel machine regression were used to investigate the association between neonicotinoids concentrations and pubertal developments. Results: High detection rates ranged from 72.0% to 100.0% for all neonicotinoids. Boys and girls with thiacloprid concentration at the >75th percentile had lower stage of genitalia development (OR: 0.83, 95% CI: 0.33-0.93) and higher stage of axillary hair development (OR: 1.46, 95% CI: 1.12-3.41), respectively, compared with those at the <25th percentile. The estimate change in genitalia stage was significantly different at or above the 75th percentile concentration of neonicotinoids mixture compared to the 50th percentile concentration. No associations were found between other urinary neonicotinoids and other indicators of puberty. Conclusions: Higher thiacloprid concentration was associated with delayed genitalia development in boys and early axillary hair development in girls. Neonicotinoids mixture was negatively associated with genitalia stage in the joint effect. Given the characteristic of the cross-sectional study, our results need further confirmation of the causal relationship.
Article
Hair is a deeply rooted component of identity and culture. Recent articles in this series have focused on scientific evidence relating to hair growth and new insights into the pathogenesis and mechanism of hair loss. This article reviews emerging evidence that has advanced our understanding of hair growth in both of these areas to provide a context for outlining current and emerging therapies. These include finasteride, minoxidil, topical prostaglandins, natural supplements, microneedling, low-level laser light, platelet-rich plasma, fractional lasers, cellular therapy, Wnt activators and SFRP1 antagonism.
Chapter
Hair follicles are complex, minuscule, dynamic organs found only in mammals, representing one of their most defining features. Despite their tiny size, they possess impressive physiological properties, often overlooked by those who can be misled by their small size. Some properties of the hair follicle in mammals are unique and extremely diverse: sensation, protection, camouflage, thermal regulation and insulation, decoration, cleansing, transport, pigmentation, dispersion of sebum, and pheromones, signaling, and communication, even stem cells reserving for renewal and reparative responses. Hair cannot be, therefore, scientifically ignored.
Chapter
Ηardy described the hair follicle as “a treasure waiting to be discovered by even more molecular biologists” [1]. And there is nothing more intriguing about hair follicle physiology than its life cycle.
Article
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Hair loss in women has been considered one of the most common problems faced the dermatologists. It is also considered a haunting problem for women because of the association of hair with femininity, beauty and personal strength, and thus can cause psychological problems for them. In Iraq, there was a little attention was advocated to determine the most type and prevalence of hair loss accurately and the associated causes. The aim of the study is to highlight the main physiological causes of hair loss for women in Basra Governorate, Southern Iraq. Given the important role that some hormones and nutrients play in addition to oxidative stress in influencing the appearance of hair loss disease in women. The study was conducted on volunteer patients that visiting the dermatology consultation unit in hospitals affiliated to the Basra Health Administration during the period from September 2019 to the beginning of January 2020. The study was applied on a random sample consisting of 67 women suffering from hair loss and another sample of 21 women as control volunteers sound for the purpose of comparison. The results of the current study have revealed a significant decrease in blood parameters (MCH-MCV-Hb) and a decrease in the level of iron in the patients group compared with the control group indicating the association of anemia with hair loss in women. The results showed a significant decrease in the concentration of zinc and vitamin D in the patients group compared with the control group. The results also showed a significant increase in the concentration of testosterone and a significant decrease in the level of estrogen and thyroid hormone T3 in the group of patients compared to the control group. Furthermore, the results presented a high level of (MDA) among the patients group compared to the control group, indicating that increased oxidative stress may cause hair loss in women.
Chapter
This chapter is a revised version of the Puberty chapter published in the second edition. The principal changes include updates to the proximate regulators of pubertal hypothalamic GnRH secretion, a brief section on epigenetics, and slight alterations in language to acknowledge that, while biological studies of puberty treat individuals as sexually dimorphic, lived experience varies. New references have been inserted among the pre-existing ones but have not been numbered so that, if revisions are required, the work of formatting and ordering need not take place a second time. They are highlighted in the bibliography to make them easily visible. All tables and figures remain the same except Fig. 5.3. If possible, I would like to include a revised version of this figure that appeared in an Annual Review of Anthropology article (by Reiches). That file is attached below.
Article
Androgenetic alopecia (AGA) management is a significant clinical and therapeutic challenge for transgender and gender diverse (TGD) patients. Although gender-affirming hormone therapies affect hair growth, there is little research about AGA in TGD populations. After reviewing the literature on approved treatments, off-label medication usages, and procedures for treating AGA, we present treatment options for AGA in TGD patients. First-line treatments for any TGD patient include topical minoxidil 5% applied to the scalp once or twice daily, finasteride 1 mg oral daily, and/or low-level laser light therapy. Spironolactone 200 mg daily is also first-line for transfeminine patients. Second-line options include daily oral minoxidil dosed at 1.25 or 2.5 mg for transfeminine and transmasculine patients, respectively. Topical finasteride 0.25% monotherapy or combination with minoxidil 2% solution are second-line options for transmasculine and transfeminine patients, respectively. Other second-line treatments for any TGD patient include oral dutasteride 0.5 mg daily, platelet-rich plasma, or hair restoration procedures. After 6-12 months of treatment, AGA severity and treatment progress should be assessed via non-sex-based scales, e.g. the Basic and Specific Classification or the Bouhanna scales. Dermatologists should coordinate care with the patient’s primary gender-affirming clinician(s) so that shared knowledge of all medications exists across the care team.
Article
Topical 17-beta-estradiol (E2) regulates the hair cycle, hair shaft differentiation, and sebum production. Vitamin A also regulate sebum production. Vitamin A metabolism proteins localized to the pilosebaceous unit (PSU; hair follicle and sebaceous gland); and were regulated by E2 in other tissues. This study tests the hypothesis that E2 also regulates vitamin A metabolism in the PSU. First, aromatase and estrogen receptors localized to similar sites as retinoid metabolism proteins during mid-anagen. Next, female and male wax stripped C57BL/6J mice were topically treated with E2, the estrogen receptor antagonist ICI 182,780 (ICI), letrozole, E2 plus letrozole, or vehicle control (acetone) during mid-anagen. E2 or one of its inhibitors regulated most of the vitamin A metabolism genes and proteins examined in a sex dependent manner. Most components were higher in females and reduced with ICI in females. ICI reductions occurred in the premedulla, sebaceous gland, and epidermis. Reduced E2 also reduced RA receptors in the sebaceous gland and bulge in females. However, reduced E2 increased the number of retinal dehydrogenase 2 positive hair follicle associated dermal dendritic cells in males. These results suggest that estrogen regulates vitamin A metabolism in the skin. Interactions between E2 and vitamin A have implications in acne treatment, hair loss, and skin immunity.
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Background Pilonidal disease is common amongst adolescent males and females and often leads to recurrent symptoms and life-altering morbidity. The traditional surgical approach includes wide excision of the involved area and carries a high rate of postoperative morbidity. A minimally invasive surgical approach using trephines was described by Gips in 2008 and has since been widely adopted by many surgeons. The aim of this study was to explore outcomes of the trephination procedure for pediatric and adolescent patients by evaluating postoperative wound healing and disease recurrence. Materials and Methods A retrospective cohort study for patients that underwent the trephination procedure as part of standard of care for the treatment of pilonidal disease from November 1, 2019-November 1, 2020 was performed. Patient demographics, presenting characteristics, and previous treatment history were identified. Outcome measures included healing time, recurrent disease, and need for reoperation. Results A total of 19 patients underwent the trephination procedure at a mean age of 16.4 years of age. An average of 3.8 pits were excised and there were no reported intraoperative complications. Following trephination, 26.3% of patients were healed at 30-day’s, with just over 40% showing complete healing by 6-months. The recurrence rate was 16.1% at 6-months and approximately 15% of patients required a second surgery. Conclusion Early results for trephination at our institution show a high rate of healing complications and frequent reoperation. Future research is needed to establish the role of the trephination procedure in the context of defining the best practices for treating this challenging disease.
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Background Autologous hair transplantation has been the convention in cases of androgenic alopecia. Routinely, the occipital area serves as an ideal donor site. The advent of follicular unit extraction (FUE) has made body and beard hair harvest a possibility. Beard hair, in particular, has been far more sought after than other parts of the body.Materials and MethodsA case series of 20 patients have been documented wherein cases with Grade 6 and 7 androgenic alopecia have been treated with beard hair as an adjunct donor site. The local anatomy, procedural technicalities and method of harvesting have been emphasized. The pre, intra and postoperative records have been maintained.DiscussionThe advent of FUE paved way for minimal downtime, better cosmesis and less scarring facilitating the possibility of using non-scalp hair in hair restoration, thus increasing the overall donor graft availability. Beard hair has its characteristic differences when compared to the scalp hair. Alongside there exists an array of advantages and disadvantages.Conclusion Minimal complications and potential advantages have encouraged the usage of beard graft in the recent past. In hindsight, beard to scalp transplantation is a worthwhile alternative in cases demanding an expanded source of donor hair which demands further literary contribution.
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Androgenetic alopecia is the most common disease associated with hair loss in both females and males. Given the high prevalence of androgenetic alopecia and limited therapeutic methods and the high cost of hair transplantation and ease of use or platelet‐rich plasma (PRP) therapies, this systematic review study was conducted to evaluate the effect of PRP on androgenetic alopecia of women. In this systematic review study, English‐language articles were searched on PubMed, ISI web of knowledge, and Google Scholar by the end of 2019 with a combination of keywords. Finally, 6 articles were evaluated. The total number of subjects in this systematic review study was 92 people in 6 studies. All studies were clinical trials. Most of the studied had been conducted as a pilot study. Follow‐up period for patients varied from 6 months to 12 months. Except for one study, other studies have reported a positive therapeutic effect for PRP. The major limitation of the studies was the pilot nature and small sample size of these studies. According to the limited studies included in this systematic review, PRP treatment had a positive effect on the improvement of androgenetic alopecia, increasing hair density and improving hair diameter in affected women. This article is protected by copyright. All rights reserved.
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17-β-Estradiol (10 nmol per 200 μ1 acetone) applied topically twice weekly to the clipped dorsal surface of C57BL/6 or C3H female mouse skin prevented hair growth, as previously described in the CD-1 mouse strain. Twice weekly topical application of the estrogen receptor antagonist, ICI 182 780 (10 nmol per 200 μ1 acetone), induced the telogenanagen transition and produced early pigmentation appearance in skin and hair growth in C57BL/6 and C3H female mice. Whereas twice weekly topical application of 10 nmol 17-β-estradiol blocked hair growth, the intraperitoneal administration of this dose twice weekly did not block hair growth, suggesting a direct cutaneous effect of 17-β-estradiol. We also evaluated the effect of 17-α-estradiol, 17-β-estradiol, and ICI 182 780 on hair growth in male mice. As observed in female mice, 17-β-estradiol was a potent inhibitor of hair growth and ICI 182 780 stimulated hair growth; however, unlike the results previously observed in female mice, 17-α-estradiol was a potent inhibitor of hair growth in male mice. These results demonstrate that (i) the route of administration of 17-β-estradiol is critical for its ability to block hair growth; (ii) C57BL/6 and C3H mice, two commonly employed mouse strains for hair growth studies, responded to 17-β-estradiol and ICI 182 780 in a manner similar to that described in CD-1 mice; and (iii) the hair follicles of male and female mice respond similarly to 17-β-estradiol and ICI 182 780, but display striking sex differences in the response to 17-α-estradiol on hair growth.
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A two-year field study of colour change in a population of Mountain hares showed that the rate of colour change was significantly faster in a warm spring than in a cold one. The same result was found in individually marked wild hares, indicating that the response is not due to differences in age or sex ratios. It is postulated that the white coat is for camouflage, and the duration for which it is worn is correlated with temperature because of the coat's thickness. Moulting is probably timed by daylength, and the rate of moult affected by temperature.
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Hair loss in women is a very common clinical complaint, and is usually associated with severe emotional distress. In this article, the authors review the most common clinical causes of hair loss in women, and emphasize the role of hormonal changes in the regulation of hair loss and hair growth.
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Hair-follicle regression in the bald scalps of stumptailed macaques develops after puberty, which corresponds to an elevation of serum testosterone and dihydrotestosterone. Using the cultured cells from the pre- and postpubertal macaques, we examined the role of dermal papilla cells in testosterone-induced inhibition of outer root sheath cell proliferation. Testosterone showed no effects on proliferation of either dermal papilla cells or outer root sheath cells cultured alone. Testosterone-induced inhibition of outer root sheath cell proliferation occurred only in coculture with dermal papilla cells derived from the bald scalps of adult macaques but not with dermal papilla cells from the hairy occipital scalps of adult macaques or the prebald frontal scalps of juvenile macaques. Furthermore, RU 58841, an androgen receptor blocker, antagonized this testosterone-elicited inhibition. Together our data indicate that the inhibitory effect of testosterone on proliferation of epithelial cells is age dependent, a...
Chapter
This chapter reviews the functions of hair, its structure and the processes occurring during the hair growth cycle, the changes which can occur with the seasons, and the importance of the main regulator of human hair growth, the androgens. Its main focus lies on human hair growth. Mammalian skin produces hair everywhere except for the glabrous skin of the lips, palms, and soles. Although obvious in most mammals, human hair growth is so reduced with tiny, virtually colorless vellus hairs in many areas, that we are termed the “naked ape.” Externally hairs are thin, flexible tubes of dead, fully keratinised epithelial cells; they vary in color, length, diameter, and cross-sectional shape. Inside the skin hairs are part of individual living hair follicles, cylindrical epithelial downgrowths into the dermis, and subcutaneous fat, which enlarge at the base into the hair bulb surrounding the mesenchyme-derived dermal papilla. Human hair's main functions are protection and communication; it has virtually lost insulation and camouflage roles, although seasonal variation and hair erection when cold indicate the evolutionary history. Children's hairs are mainly protective; eyebrows and eyelashes stop things entering the eyes, while scalp hair probably prevents sunlight, cold, and physical damage to the head and neck.
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Red deer stags produce an androgen-dependent mane of long hairs only in the breeding season; in the non-breeding season, when circulating androgen levels are low, the neck hair resembles the rest of the coat. This study was designed to determine whether androgen receptors are present in deer follicles throughout the year or only in the mane (neck) follicles when circulating testosterone levels are high in the breeding season. Although androgens regulate much human hair growth the mechanisms are not well understood; they are believed to act on the hair follicle epithelium via the mesenchyme-derived dermal papilla. The location of androgen receptors in the follicle was investigated by immunohistochemistry and androgen binding was measured biochemically in cultured dermal papilla cells derived from mane and flank follicles during the breeding season and from neck follicles during the non-breeding season. Immunohistochemistry of frozen skin sections using a polyclonal antibody to the androgen receptor localised nuclear staining only in the dermal papilla cells of mane follicles. Saturation analysis assays of 14 primary dermal papilla cell lines using [(3)H]-mibolerone demonstrated high-affinity, low-capacity androgen receptors were present only in mane (breeding season neck) cells; competition studies with other steroids confirmed the specificity of the receptors. Androgen receptors were not detectable in cells from either the breeding season flank nor the non-breeding season neck follicles. The unusual biological model offered by red deer of androgen-dependent hair being produced on the neck in the breeding, but not the non-breeding season, has allowed confirmation that androgen receptors are required in follicle dermal papilla cells for an androgen response; this concurs with previous human studies. In addition, the absence of receptors in the non-breeding season follicles demonstrates that receptors are not expressed unless the follicle is responding to androgens. Androgen receptors may be induced in mane follicles by seasonal changes in circulating hormone(s).
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The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
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1. The patterns of the first and second hair growth waves, forming the second and third coats, were followed in albino rats which had been dyed black before the start of hair growth. 2. The length of hair produced during the growth waves varies from region to region of the body. These regional differences are partly the result of differences in rates of growth, but mainly due to differences in the duration of the period of follicular activity. 3. The duration of the growing and resting periods varies in different areas of the body. For example, in the ventral region the resting period between the first and second waves lasts for about 14 days and the growing period of the second wave for only 12 days, whereas in the mid-dorsal region the resting period lasts for about 4 weeks and the growing period about 19 days. 4. As the growth wave spreads over each area every follicle produces a new hair alongside the dead or 'club' hair. Loss of club hairs then begins, and the rate of loss varies from region to region of the body. 5. In female rats the growth wave moves more slowly, the definitive length of hair is shorter, and the loss of club hairs is slower than in the male. The sexual differences in hair length are the result of differing rates of growth, and there is no difference in the duration of follicular activity between the sexes. 6. It is suggested that in assessing the effect on hair growth of any treatment the following aspects should be considered: ( a ) Time of initiation of the growth wave and its duration. (The length of the resting period in any region will depend on both these factors.) ( b ) Duration of the growing period. ( c ) Rate of elongation of the hair during the growing period. ( d ) Rate of loss of club hairs.
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In the 20 yr since it was established that impairment of dihydrotestosterone formation is the cause of a rare form of human intersex, a wealth of information has accumulated about the genetics, endocrinology, and variable phenotypic manifestations, culminating in the cloning of cDNAs encoding two 5 alpha-reductase genes and documentation that mutations in the steroid 5 alpha-reductase 2 gene are the cause of 5 alpha-reductase deficiency. Perplexing and difficult problems remain unresolved, e.g. whether the variability in manifestations is due to variable expressions of steroid 5 alpha-reductase 1 or to effects of testosterone itself. It is also imperative to establish whether defects in steroid 5 alpha-reductase 2, perhaps in the heterozygous state, are responsible for a portion of cases of sporadic hypospadias, to determine whether 5 alpha-reductase plays a role in progesterone action in women, and to elucidate the relation between androgen action and gender role behavior.
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Background: Androgenetic alopecia (male pattern hair loss) is caused by androgen-dependent miniaturization of scalp hair follicles, with scalp dihydrotestosterone (DHT) implicated as a contributing cause. Finasteride, an inhibitor of type II 5α-reductase, decreases serum and scalp DHT by inhibiting conversion of testosterone to DHT. Objective: Our purpose was to determine whether finasteride treatment leads to clinical improvement in men with male pattern hair loss. Methods: In two 1-year trials, 1553 men (18 to 41 years of age) with male pattern hair loss received oral finasteride 1 mg/d or placebo, and 1215 men continued in blinded extension studies for a second year. Efficacy was evaluated by scalp hair counts, patient and investigator assessments, and review of photographs by an expert panel. Results: Finasteride treatment improved scalp hair by all evaluation techniques at 1 and 2 years (P < .001 vs placebo, all comparisons). Clinically significant increases in hair count (baseline = 876 hairs), measured in a 1-inch diameter circular area (5.1 cm2 ) of balding vertex scalp, were observed with finasteride treatment (107 and 138 hairs vs placebo at 1 and 2 years, respectively; P < .001). Treatment with placebo resulted in progressive hair loss. Patients’ self-assessment demonstrated that finasteride treatment slowed hair loss, increased hair growth, and improved appearance of hair. These improvements were corroborated by investigator assessments and assessments of photographs. Adverse effects were minimal. Conclusion: In men with male pattern hair loss, finasteride 1 mg/d slowed the progression of hair loss and increased hair growth in clinical trials over 2 years. (J Am Acad Dermatol 1998;39:578-89.)
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The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
Article
The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
Article
The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
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The mane of the African lion (Panthera leo) is a highly variable trait that reflects male condition and ambient temperature. We examined the consequences of this variation in a long-term study of lions in the Serengeti National Park, Tanzania. Mane darkness indicates nutrition and testosterone and influences both female choice and male-male competition. Mane length signals fighting success and only appears to influence male-male assessment. Dark-maned males enjoy longer reproductive life-spans and higher offspring survival, but they suffer higher surface temperatures, abnormal sperm, and lower food intake during hot months of the year. Maned males are hotter than females, and males have lighter and/or shorter manes in hotter seasons, years, and habitats. This phenotypic plasticity suggests that the mane will respond to forecasted increases in ambient temperature.
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The circadian pacemaker imposes stereotypic patterns of daily variation on the activity of human neuroendocrine systems. In a number of cases, these patterns exhibit waveforms that are characterized by distinct diurnal and nocturnal periods with relatively discrete transitions between them (corresponding to a biological day, a biological dusk, a biological night, and a biological dawn). In humans, for example, diurnal periods of absence of melatonin secretion, low prolactin secretion, and falling levels of cortisol alternate with nocturnal periods of active melatonin secretion, high prolactin secretion and rising levels of cortisol. In response to light, the circadian pacemaker synchronizes the timing of the biological day and night so that their timing and duration are appropriately matched with the timing and duration of the solar day and night. As the pacemaker carries out this function, it is able to adjust the duration of the biological day and night to match seasonal variation in the duration of the solar day and night. Thus, after humans have been chronically exposed to long nights (scotoperiods), the duration of nocturnal periods of active melatonin secretion, high prolactin secretion and rising levels of cortisol is longer than it is after they have been chronically exposed to short nights. Furthermore, the sleep-related peak of growth hormone secretion is half as high after exposure to long nights as it is after exposure to short nights. These responses to seasonal changes in duration of the natural scotoperiod are suppressed in most individuals - especially men - who live in modern urban environments in which they are exposed to artificial light after dark and artificial darkness during the daytime.
Article
Androgenetic alopecia in the female occurs much more frequently than is generally believed. The condition is still considered infrequent, for it differs, in its clinical picture and in the sequence of events leading to it, from common baldness in men. To facilitate an early diagnosis (desirable in view of the therapeutic possibilities by means of antiandrogens) a classification of the stages of the common form (female type) of androgenetic alopecia in women is presented. The exceptionally observed male type of androgenetic alopecia can be classified according to Hamilton or to the modification of this classification proposed by Ebling & Rook.
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The need for a widely accepted, accurate, and reproducible standard of classification for male pattern baldness has increased with the advent and increasing popularity of hair transplant surgery. This report establishes such a classification, and reports its use in determining the incidence of male pattern baldness at various ages in 1,000 white adult male subjects. The action of testosterone as an incitant in male pattern baldness is well known, but this study points out the continued effect of time, even in later years. Since most hair transplant surgery is peformed on subjects with male pattern baldness, and because the success of hair transplant surgery is largely dependent on proper patient selection, a complete understanding of male pattern baldness is essential for consistently good results with hair transplantation.
Article
Every other month, during the course of 14 months, the circadian rhythm in plasma testosterone (among others variables) of 5 healthy males (26 to 32 years) was documented. Subjects' synchronization: light-on at 7 ± 1 h; light-off at 23 ± 1.5 h during the whole year. Blood sampling 4-hourly, at fixed times during 28 h, for radioimmunological testosterone determinations. The cosinor method was used for statistical analyses. An annual rhythm in the testosterone 24-h mean is detected ( P < 0.025) with a peak in October (from 16 July to 26 December, with 95% confidence limits). Annual mean (± 1 se ) = 759 (± 26) ng/100 ml. Peaktrough difference = 197 ng/100 ml (from 106 to 290 with 95% confidence limits). The timing of the testosterone circadian peak, in the 24-h-scales also varies during the course of the year. The peak is found around 8 h in May and around 14 h in November, this phase-shift being statistically significant ( P < 0.05).
Article
In a groups of 15 healthy male subjects a statistically significant circannual cycle in plasma testosterone levels was assessed by sampling blood at 3-monthly intervals. Peak levels were found in summer and early autumn and a nadir in the winter and early spring.
Article
Androgens stimulate hair growth in many areas, e.g. the beard; they also induce regression and balding on the scalp with increasing age in genetically disposed individuals. The cause(s) of this biological conundrum is unknown but age-related; androgen-potentiated changes also occur in the prostate. The mesenchymederived dermal papilla situated at the base of the hair follicle is thought to play an important role in regulating the growth and development of the follicular epithelium. Since androgens probably act on the hair follicle via the dermal papilla, cultures of dermal papilla cells from human hair follicles with differing responses to androgens in vivo have been established and their ability to bind androgens assessed. Receptor binding was assayed by saturation analysis (0·05–10 nmol/l) using the synthetic non-metabolizable androgen, [ ³ H]mibolerone. Shionogi 115 cells were also assayed as a positive control. Specific high-affinity low-capacity androgen receptors were identified in 12 dermal papilla primary cell lines with similar characteristics to established androgen receptors. Cells from androgen-sensitive follicles (beard, scrotum and pubis) contained higher levels of androgen receptors than those derived from relatively androgeninsensitive non-balding scalp follicles whether the receptor content was calculated in relation to cell number, protein or DNA content of the cells. These results support the hypothesis that androgens act on hair follicles via the dermal papilla in vivo and demonstrate that dermal papilla cells exhibit an altered phenotype in culture which depends on the body site from which they were derived. Cultured human dermal papilla cells should prove a useful model system for studies of the mechanism of androgen action, and further investigations may elucidate the paradox of why bald men can grow beards. Journal of Endocrinology (1992) 133, 141–147
Article
The expression of basement membrane molecules and interstitial collagens in human hair follicle mesenchyme was studied by immunohistochemical staining of tissue sections and of cells cultured from dermal papillae. Type I and type III collagens were found in the dermal sheath and in the dermal papilla throughout the hair cycle. Laminin and type IV collagen were expressed at the outer root sheath basement membrane and in the extracellular matrix of the dermal papilla of anagen and catagen follicles. In telogen follicles, where the volume of the dermal papilla extracellular matrix is much reduced, outline staining of dermal papilla cells for laminin and type IV collagen was still apparent. Staining for bullous pemphigoid antigen was also seen at the outer root sheath basement membrane extending to the lower tip of the hair bulb. In anagen follicles, there was no staining for bullous pemphigoid antigen at the interface between hair bulb epithelium and the dermal papilla and no staining within the dermal papilla. However, linear staining for bullous pemphigoid antigen became continuous around hair follicle epithelium during catagen and telogen. Cells cultured from human dermal papillae also stained for interstitial collagens, type IV collagen and laminin. However, similar results were obtained when cultured dermal fibroblasts were stained with the same antibodies. The expression of basement membrane proteins in human dermal papillae resembles that seen in follicles from other mammalian species and suggests that this is relevant to dermal papilla function. Cultured dermal papilla cells express a similar pattern of interstitial collagens and basement membrane proteins to those seen in tissue sections but this finding is not specific to dermal papilla cells.
Article
Various parameters of hair growth were determined every 28 days for 18 months in 14 healthy Caucasian men aged 18-39 with indoor occupations in Sheffield, U.K. (latitude 53.4 degrees N). In the scalp the proportion of follicles in anagen reached a single peak of over 90% in March, and fell steadily to a trough in September. The number of shed hairs reached a peak around August/September, when least follicles were in anagen. At this time the average loss of hairs was about 60 per day, more than double that during the preceding winter. The rate of growth of the beard was lowest in January and February and increased steadily from March to July to reach a peak about 60% above the winter level. The rate of growth of thigh hair showed a similar pattern though with less pronounced differences. No seasonal fluctuations in finger- or toenail growth were detected.
Article
The activity of 5 alpha-reductase was assessed in cultured human beard dermal papilla cells and reticular dermal fibroblasts to elucidate the mechanism of androgen action in promoting the growth of beards in men. The monolayer was incubated with 50 nM of [1,2-3H]-testosterone. Steroids were extracted from the medium and analyzed by thin layer chromatography. The major metabolite in the beard dermal papilla cells was dihydrotestosterone (DHT), the most potent androgen in the androgen target tissue. By contrast, the amount of DHT formed was similar to that of androstenedione in reticular dermal fibroblasts. The 5 alpha-reductase activity in beard dermal papilla cells was three to five times as high as that in the reticular dermal fibroblasts from the same skin sample. The apparant Michaelis constant of 5 alpha-reductase in the beard dermal papilla cells was 1.0 X 10(-6) M, which was virtually equivalent to that of genital skin fibroblasts, typical androgen target cells. It was 4.0 X 10(-5) M in reticular dermal fibroblasts. By contrast, the activities of 5 alpha-reductase in dermal papilla cells from occipital scalp hair follicles were similar to those of reticular dermal fibroblasts of the same skin samples. These results strongly suggest that the beard dermal papilla cell is an androgen target cell, and that DHT plays a role in the growth of beards in men.
Article
Inconsistent with the view that hair follicle stem cells reside in the matrix area of the hair bulb, we found that label-retaining cells exist exclusively in the bulge area of the mouse hair follicle. The bulge consists of a subpopulation of outer root sheath cells located in the midportion of the follicle at the arrector pili muscle attachment site. Keratinocytes in the bulge area are relatively undifferentiated ultrastructurally. They are normally slow cycling, but can be stimulated to proliferate transiently by TPA. Located in a well-protected and nourished environment, these cells mark the lower end of the "permanent" portion of the follicle. Our findings, plus a reevaluation of the literature, suggest that follicular stem cells reside in the bulge region, instead of the lower bulb. This new view provides insights into hair cycle control and the possible involvement of hair follicle stem cells in skin carcinogenesis.
Article
Prevasectomy levels of plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), estradiol (E2), and 20 alpha-dihydroprogesterone (20 alpha-DHP), as well as semen analyses including semen volume, sperm count, and sperm motility from 260 healthy men were evaluated for annual changes. A statistically significant (P less than or equal to 0.015) high-amplitude seasonal variation with the peak in April to May was detected in semen volume, sperm count, and sperm motility. A statistically significant (P less than or equal to 0.04) annual change of moderate T to large FSH amplitude was detected in each of the five plasma endocrine variables as well. Plasma LH, T, and E2 peaked in autumn, while FSH and 20 alpha-DHP peaked in summer. Analysis of postvasectomy LH, FSH, E2, 20 alpha-DHP, and T blood levels for the 3 years following vasectomy revealed loss of seasonal rhythmicity as a group phenomenon in LH, E2, and T. The amplitude of the seasonal variation in FSH was decreased and that in 20 alpha-DHP was unchanged compared with before-vasectomy baselines. For those annual rhythms which persisted following vasectomy, the peak time was unchanged. Compared with the prevasectomy group annual mean, that for each of the endocrine values was unchanged, except for that of LH and T, which was slightly, yet statistically significantly, elevated. The existence of prominent annual variation implicates their consideration in the design of research protocols involving investigation of reproductive phenomena in human beings.
Article
In the male badger we showed that hair growth and molt are related to plasma testosterone and thyroxine cycles. We established the action of testosterone by castration and subcutaneous testosterone implants, and the action of thyroxine by thyroidectomy and dietary supplementation with thyroxine. The following groups of animals were studied: controls, thyroidectomized, thyroidectomized and thyroxine-treated, castrated, castrated and thyroxine-treated, thyroidectomized and castrated and thyroxine-treated, castrated and testosterone-implanted, and intact testosterone-implanted. In control animals, molt and hair growth occurred during the summer, with a maximum growth in autumn. Molt ended at the beginning of winter when the plasma testosterone level had started to rise, and began again after this level had started to decline. Both the start of molt and the period of maximum hair growth coincided with high thyroxine levels of about 20 ng/ml. Castration advanced molt and hair follicle activity, whereas testosterone implants delayed both molt and hair growth. In thyroidectomized badgers, neither hair growth nor seasonal molt was observed. However, when thyroxine levels were restored to 20 ng/ml or more by dietary T4 supplementation, molting was resumed in animals that had undergone either thyroidectomy or thyroidectomy plus castration. In those that underwent castration only, the molt was advanced leading to early hair growth further stimulated by the suppression of testosterone. Testosterone had an inhibitory effect on the molt--since testosterone implants in intact control animals delayed it by 4 weeks--but did not inhibit it completely. On the other hand, a T4-enriched diet advanced the date of the molt. However, the molt could not be induced, nor could hair follicle growth be reactivated, at all times during the annual cycle. Thus, in castrated animals. T4 enrichment of the diet in early January, at the end of the molt, caused follicle reactivation only toward the end of May, despite the lack of testosterone. This 18-week latency period from January to May might therefore constitute a "refractory period" in this species. The above findings show that the regulation of the seasonal molt and hair growth in the European badger involves both the thyroid and genital axes. This regulation is discussed in terms of joint control by the hypothalamus and pituitary governed, in turn, by an external factor--the photoperiod--considered to be the main synchronizer.
Article
Extract: Data are provided which concern daytime levels of circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol and progesterone in healthy female children and adolescents. These findings are correlated with sexual and skeletal maturation. Serum estradiol and testosterone levels were low in childhood, but rose to adult levels coincident with the appearance of secondary sexual characteristics. Serum LH levels did not rise above prepubertal levels until these characteristics were already apparent. Serum FSH levels showed a biphasic pattern with age; widely scattered values, some into the adult range, were seen in infancy. Mean FSH levels then declined throughout childhood until the onset of clinical puberty at which time they increased again to adult levels. Serum progesterone concentrations remained low (below 150 ng/100 ml) until menarche. Levels of serum progresterone which suggested possible ovulation and corpus luteum formation (over 200 ng/100 ml) were found in 9 of 30 girls who were less than 3 years postmenarchal.
Article
Extract: Data are provided on levels of circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone in healthy male children and adolescents, and these levels are correlated with the stage of sexual maturation, bone maturation, whole body 40K content, and the 24-hr excretion of creatinine, estrogens, 17-hydroxy-corticosteroids, total 17-ketosteroids, and fractionated ll-deoxy-17-ketosteroids (see Tables I and II).
Article
.— Twenty scalp hairs were plucked from each of 131 Caucasoid women, and measurements of diameter, at 1 mm intervals, starting just above the root, were made for each hair. There was little variation in diameter along normal anagen hairs in any of the subjects. The mean anagen hair diameter in 58 women with diffuse hair thinning, of whom 44 were without detectable endocrine abnormality and 14 were clinically hypothyroid, significantly decreased with age. This appeared to be an accentuation of a normal trend, although this could not be statistically established in the control group of 73 women. At any age the mean thickness of hair in the subjects with diffuse thinning was less than in normal subjects of the same age. Normal subjects showed a symmetrical distribution of hair diameter, with a marked peak at 0.08 mm. In contrast, subjects with diffuse alopecia without detectable endocrine abnormality showed a wide spread of diameters, with 2 equal peaks at 0.04 mm and 0.06 mm The hypothyroid group showed a similar distribution, except that there was a larger proportion of hairs of the smaller diameters. The results suggest that, in the development of diffuse thinning, not all follicles behave identically, and that there may be more than one type of follicle in the human scalp.
Article
Six young men were fed a protein-free liquid diet, which was complete in all other nutrients. Consistent and significant hair root morphological changes were evident at 11 days of depletion. These included bulb diameter reduction, atrophy, dyspigmentation, and sheath absence. The growth phase did not change. Urinary nitrogen reached minimum values by 11 days. Total serum protein and albumin levels remained normal. When protein was added to the diet, the hair root changes were reversed.
Article
Hair growth from the vertex, temple, mustache, finger, arm and leg of three Japanese men (60, 30, and 21 years of age) was measured by direct observation from October, 1966 to November 1968. Detailed information regarding hair growth cycles in the regions tested is presented.
Article
Three basic hair patterns of the scalp are recognized. These are totopilose, indentato-pilose, and indentato-circulo-pilose. The indentato-pilose has the highest incidence in both white and Negro males, and the totopilose is over four times more common in the Negroes than in the whites. The indentato-pilose has high correlation with the pecto-sterno-infraclavicular chest hair pattern in both groups.