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... 40 Hair follicle growth cycling modulation in alopecia areata There are three key phases of the hair cycle: the growth phase (anagen), the regression phase (cata- gen), and the resting phase (telogen). 43 The cycling of these phases is finely coordinated by the expres- sion of hormones, cytokines, transcription factors, and their corresponding receptors and is carefully regulated through endocrine, paracrine, and auto- crine routes. The disruption of these finely tuned pathways can result in the development of hair diseases. ...
... Correspondingly, inflammatory cell infiltration occurs in early anagen follicles without migration to draining lymph nodes as follicles capit- ulate and return to telogen. 43,45 Finally, when AA is chronic, the hair follicles tend to persist in a pro- longed telogen phase without an apparent attempt to return to an anagen growth phase (Fig 14). 38,43,45 Autoimmune activity in alopecia areata ...
... 43,45 Finally, when AA is chronic, the hair follicles tend to persist in a pro- longed telogen phase without an apparent attempt to return to an anagen growth phase (Fig 14). 38,43,45 Autoimmune activity in alopecia areata ...
... Extensive research has examined hair follicle embryogenesis and its control, though our understanding of the biological mechanisms involved is still quite limited. 4,5 However, it is clear that very specific signalling through multiple pathways is required for the correct development and geographical distribution of hair follicle formation in the skin. 6 Though very rare and typically due to a genetic modification, perturbations in hair follicle embryogenesis result in hypotrichosis, a deficiency of hair growth from birth. ...
... Hair fibers are classed into 3 different groups and size is the key feature that determines their categorization. 4,8 Most of our hair follicles produce short, fine, nonpigmented vellus hairs. In contrast, eyebrow, eyelash, and scalp follicles produce much bigger, slowly cycling, usually pigmented, terminal hairs from birth. ...
... 7 There are 3 main hair follicle growth cycling phases: anagen, when follicles are actively growing hair fiber; hair follicle regression during catagen; and a telogen quiescent resting phase. 4,9 How long each phase takes partly depends on the type of hair follicle involved and its geographic location. On the scalp, about 85% of scalp hair follicles are in anagen and 15% are normally in telogen. ...
Article
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There are many hair disorders, all of which involve alterations in normal hair biology. Essentially, hair disorders involve changes to hair fiber caliber, density per unit area, and/or the duration of anagen and telogen in the hair growth cycle. Hair disorders may be triggered by inflammation, genetics, the environment, or hormones; the relative contributions of these factors vary for different hair disorder diagnoses. Suitable treatments may either address the underlying causal factors or directly act on hair follicle biology. The objectives are to normalize the hair growth cycle, modulate the size of hair follicles, and potentially regenerate hair follicles to stabilize hair density. The purpose of this manuscript is to review the basic biology of the hair follicle, as well as causal mechanisms for the disordered hair follicle using some selected examples of hair disorders. ©2015 Frontline Medical Communications.
... In general, lighter hair is thinner while darker hair is thicker; in Europeans, fair hair measures about 40-80 µm, compared to dark brown hair, which has an average diameter of 50-90 µm (Vogt et al., 2008). Across ethnicities, the cross-sectional shape of the hair follicle determines the shape of the hair shaft in determining its curliness-round follicles produce straight hair while flat or oblong follicles produce wavy or curly hair. ...
... Human follicle formation begins in the 8th to 12th weeks of gestation, with the development of the follicle and hair fiber cell differentiation followed by growth of the hair fiber (Paus & Cotsarelis, 1999;Schmidt-Ullrich & Paus, 2005). Previous research has shown that hair follicle morphogenesis is affected by a complex network of autocrine, paracrine, and endocrine signaling pathways, as well as regulatory pathways; however, the nature of their interactions and relative significance is not well understood (Vogt et al., 2008). ...
Article
Hair diameter and curvature are two characteristics of human scalp hair used in forensic contexts. While previous data show that subjective categorization of hair curvature is highly heritable, the heritability of objectively measured curvature and diameter, and variability of hair characteristics within each individual have not yet been studied. The present study measured hair diameter and curvature using an optical fiber diameter analyzer in a sample of 2,332 twins and siblings. Heritability was estimated using maximum likelihood structural equation modeling. Results show sex differences in the magnitude of genetic influence for mean diameter and curvature, with the vast majority of the variance accounted for by genetic effects in males (diameter = 86%, curvature = 53%) and females (diameter = 77%, curvature = 61%). The consistency of diameter (variance within an individual) was also highly heritable, but did not show sex limitation, with 68% of the variance accounted for by genetic factors. Moderate phenotypic correlations were seen between diameter and consistency ( r = 0.3) but there was little correlation between diameter and curvature ( r = -0.13). A bivariate Cholesky analysis was used to estimate the genetic and environmental correlations between hair diameter and consistency, yielding genetic correlations of r gF = 0.27 for females and r gM = 0.25 for males.
... Changes in the hair cycle result in hair growth disorders, 1 the most frequent being androgenetic alopecia (AGA), commonly known as male pattern baldness. 2 AGA affects approximately 50% of men and 20-53% of women by age 50 years. 3 Currently, the available treatment for AGA involves the use of drugs such as minoxidil and finasteride. ...
... Four dimensions (50, 100, 200 and 400 lm) were chosen based on histological studies of the hair follicle, which showed that a human hair follicle is approximately 150-200 lm in diameter at its root. 2 The ratio between the diameter of the center islet and the diameter of the microwell is 1:3, since the diameter of the mesenchymal condense enclosed by hair matrix cells is nearly one third of the diameter of lower hair bulb. The side views of PDMS patterned from the silicon master were shown in Figure 2(A) (i-iv). ...
Article
Hair follicle transplantation is often used in the treatment of androgenetic alopecia (AGA). However, the only source of hair follicles is from human donors themselves, which limits the application of this approach. One possible solution is to reconstitute hair follicle from dissociated cells. Currently, a number of microscale technologies have been developed to create size and shape controlled microenvironments in tissue engineering. Photopolymerizable PEGDA hydrogels are often selected as promising scaffolds in engineered microtissues due to their biocompatibility and adjustable mechanical properties. Here, we fabricated an array of PEGDA microwells with center islets that mimic the architecture of human hair follicles using soft lithography. Dermal and epithelial cells were seeded in different compartments of the microstructured mould to mimic mesenchymal and epithelial compartmentalization in native hair follicles. We demonstrated that these compartmentalized microstructures support cell proliferation and cell survival over 14 days, and spreading of dermal fibroblasts was observed. This hydrogel micromould provides a potentially useful tool for engineering 3D hair follicle-mimicking complex cultures in vitro. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
... Normal scalp is characterized by the presence of follicular units containing about 2-4 terminal hairs and 1 or 2 vellus hairsof uniform thickness and color [17][18][19][20]. The mean thickness of normal hair was about 0.06 mm [19]; however, up to 10% of hairs are represented by vellus hairs which lack the medulla [6,21,22]. A normal terminal hair is uniform in thickness and color throughout its length, however, vellus hairsare lightly pigmented [21,22]. ...
... The mean thickness of normal hair was about 0.06 mm [19]; however, up to 10% of hairs are represented by vellus hairs which lack the medulla [6,21,22]. A normal terminal hair is uniform in thickness and color throughout its length, however, vellus hairsare lightly pigmented [21,22]. Simple, fine red loops, which represent capillaries within the dermal papillae, are generally visible among hairs, and the subpapillary plexus is visible as linear arborizing vessels. ...
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Hair and scalp examination techniques can be classified into three categories: noninvasive methods (clinical history, general examination, photography, hair count, weighing shed hair, pull test, global hair counts, dermoscopy, electron microscopy, laser scanning microscopy, etc.); semi‐invasive methods (the trichogram, unit areatrichogram); and invasive methods (biopsies in cicatritial alopecia). Scalp dermoscopy or trichoscopy is one of thenoninvasive techniques for the evaluation of patients with hair loss that allows for magnified visualization of the hair and scalp skin. It may be performed with a manual dermoscope (10× magnification) or a videodermoscope (up to 1000× magnification). This method is simple, quick, and easy to perform, is well‐accepted by patients, and is useful for monitoring treatment, determining severity of the disease and follow‐up. It is a simple, minimally invasive and rapid technique for measuring hair follicle activity. Trichogram represents a semi‐invasive technique for the evaluation of patients with hair loss that allows the microscopic examination of hairs plucked from the scalp and provides information about the state of the proximal end of the hair shaft and the distal end. The trichogram is a useful complementary tool for clinical evaluation, diagnosis, and the monitoring of treatment response.
... However, follicles retain a degree of plasticity with respect to the type of hair produced and a number can transform from vellus into terminal hair production and visa versa. This is particularly seen during puberty when androgen responsive vellus hair follicles are promoted into terminal follicles [5]. ...
... The time duration of each phase depends on the type and location of the hair follicle. Under physiological conditions, approximately 85% of scalp hair follicles are in anagen while 15% are in a telogen phase [5]. The duration of anagen in healthy scalp hair follicles is typically 2-6 years and is the principle determinant of hair length. ...
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Hair follicles are complex skin appendages, the perturbations of which have an impact on human health and emotional welfare disproportionate to their small dimensions. Changes to the parameters of hair follicle size, numbers per unit area of skin, and growth cycle time duration determine hair coverage and fundamentally underlie the diagnosis of an individual with alopecia or hypertrichosis. Here we review the hair follicle's physiology, its disorders and principles of hair disorder treatment development.
... Hair life cycle. Reproduced with permission from[33], published by Springer Berlin Heidelberg, 2008. ...
Article
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Hair can be strategically divided into two distinct parts: the hair follicle, deeply buried in the skin, and the visible hair fiber. The study of the hair follicle is mainly addressed by biological sciences while the hair fiber is mainly studied from a physicochemical perspective by cosmetic sciences. This paper reviews the key topics in hair follicle biology and hair fiber biochemistry, in particular the ones associated with the genetically determined cosmetic attributes: hair texture and shape. The traditional and widespread hair care procedures that transiently or permanently affect these hair fiber features are then described in detail. When hair is often exposed to some particularly aggressive cosmetic treatments, hair fibers become damaged. The future of hair cosmetics, which are continuously evolving based on ongoing research, will be the development of more efficient and safer procedures according to consumers’ needs and concerns.
... (LJZ) with species and body site. Many disorders inducing hair loss are extensively exhibited and discussed including hypotheses on skull expansion relating to alopecia and the clinical evaluation [8,9]. Androgenic alopecia (AGA) is the main attention of the present article based on its clinical importance. ...
Article
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Hair loss may not be recognized as a life-threatening disorder. However, it has a great harm on a person's self-respect, mental health, and entirety quality of life. Androgenic alopecia (AGA) is the most common type of hair loss, which affects a great number of both men and women. Alopecia can be treated with various hair loss strategies, including hair transplant, cosmetics and medication. Medical treatment shows the outstanding ability in improving hair growth. Plenty of drugs prevent alopecia by inhibiting the secretion of male hormone. But these medicines exhibit some undesirable side effects. Since hair loss requires a long-term treatment, and minimizing adverse side effects is extremely urgent in drug development. Accordingly, new agents are obtained from natural products with less adverse effects. Traditional Chinese medicines exhibit unique advantages in hair loss treatment. This review generalizes and analyzes the recent progress of medicinal plants for the treatment of hair loss, suggested mechanisms and outlines a number of trials taken or underway to optimize the treatment.
... Biopsy: Punch Biopsy was taken in 29 cases, histopathology report showed both anagen and telogen follicles with peri follicular lymphocytic infiltrate which was in concordance with previous studies. 15,16 Type of AA: In the present study most common type of AA is patchy type 73%, followed by ophiasis in 7%, sisaphio in 7%, totalise in 4%, universalise in 3%, reticulate in 3%, diffuse in 3% of cases which were comparable to Thomas et al. 5 study. ...
... The density of beard hair follicles varies with facial area and ethnicity. Values range between 20 and 80 follicles/cm 2 [3,17]. High densities of beard hair follicles can contribute to multiple stroke shaving. ...
Article
The challenge of shaving is to cut the beard hair as closely as possible to the skin without unwanted effects on the skin. To achieve this requires the understanding of beard hair and male facial skin biology as both, the beard hair and the male facial skin, contribute to the difficulties in obtaining an effective shave without shaving-induced skin irritation. Little information is available on the biology of beard hairs and beard hair follicles. We know that, in beard hairs, the density, thickness, stiffness, as well as the rates of elliptical shape and low emerging angle, are high and highly heterogeneous. All of this makes it challenging to cut it, and shaving techniques commonly employed to overcome these challenges include shaving with increased pressure and multiple stroke shaving, which increase the probability and extent of shaving-induced skin irritation. Several features of male facial skin pose problems to a perfect shave. The male facial skin is heterogeneous in morphology and roughness, and male skin has a tendency to heal slower and to develop hyperinflammatory pigmentation. In addition, many males exhibit sensitive skin, with the face most often affected. Finally, the hair follicle is a sensory organ, and the perifollicular skin is highly responsive to external signals including mechanical and thermal stimulation. Perifollicular skin is rich in vasculature, innervation and cells of the innate and adaptive immune system. This makes perifollicular skin a highly responsive and inflammatory system, especially in individuals with sensitive skin. Activation of this system, by shaving, can result in shaving-induced skin irritation. Techniques commonly employed to avoid shaving-induced skin irritation include shaving with less pressure, pre- and post-shave skin treatment and to stop shaving altogether. Recent advances in shaving technology have addressed some but not all of these issues. A better understanding of beard hairs, beard hair follicles and male facial skin is needed to develop novel and better approaches to overcome the challenge of shaving. This article covers what is known about the physical properties of beard hairs and skin and why those present a challenge for blade and electric shaving, respectively. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.
... Фаза роста определяет длину волос. Большая часть волос кожи головы (85-90 %) находятся в фазе анагена, которая является стадией роста цикла волосяного фолликула и длится в течение 2-6 лет, что определяет длину и диаметр волос [15]. 10-15 % волос находятся в фазе телогена, которая является фазой отдыха цикла волосяного фолликула и длится около 3 месяцев. ...
Article
Background. Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders, affecting 5–10 % of reproductive-aged women. The dermatologic manifestations of PCOS play a significant role in diagnosis. The purpose of the present study was to examine the impact of androgenic alopecia among patients with PCOS and to define their most significant trichological features. Because the data on dermatologic changes associated with PCOS are rather scarce, the present study was designed to determine the incidence and prevalence of androgenic alopecia. Materials and methods. We conducted a prospective observational study of patients with PCOS. The diagnosis of PCOS was made according to the consensus criteria adopted in May 2003 in Rotterdam. Each patient signed informed consent, and then a general physical examination, systemic examination, breast and pelvic examination, as well as a detailed trichological examination were carried out. Results. Twenty women with PCOS participated in the study. The median age was 28.7 ± 6.2 years. Oligo/anovulation frequency was 63.2 %, hirsutism frequency – 68.4 %. In our study, the prevalence of androgenic alopecia was found to be 30 %, telogenic hair loss – 55 %, absence of alopecia signs in 15 % of cases. Conclusions. Androgenic alopecia is a prevalent but unreliable marker of biochemical hyperandrogenism. It is therefore imperative for the treating physicians to understand the adverse effects associated with PCOS, recognize these potential health risks in patients, and treat them accordingly.
... These and other studies demonstrate that DP cells retain knowl- edge of size and shape of the hair follicle they should form and that they retain a memory of their hair cycle clock (Matsuzaki and Yoshizato, 1998;Ohyama et al., 2010;Vogt et al., 2008;Waters et al., 2007). Morphogenesis of all structures of mesenchymal ori- gins appears to reflect striking similarities (Hall and Miyake, 2000;Widelitz et al., 1997). ...
Article
Across many tissues and organs, the ability to create an organoid, the smallest functional unit of an organ, in vitro is the key both to tissue engineering and preclinical testing regimes. The hair follicle is an organoid that has been much studied based on its ability to grow quickly and to regenerate after trauma. But hair follicle formation in vitro has been elusive. Replacing hair lost due to pattern baldness or more severe alopecia, including that induced by chemotherapy, remains a significant unmet medical need.By carefully analyzing and recapitulating the growth conditions of hair follicle formation, we recreated human hair follicles in tissue culture that were capable of producing hair. Our microfollicles contained all relevant cell types and their structure and orientation resembled in some ways excised hair follicle specimens from human skin. This finding offers a new window onto hair follicle development. Having a robust culture system for hair follicles is an important step towards improved hair regeneration as well as to an understanding of how marketed drugs or drug candidates, including cancer chemotherapy, will affect this important organ.
... While this may seem trivial, these textures have carried colonial geographical connotations for centuries, with scientific research using hair texture uncritically to denote and classify race and culture. In this vein, typically circular hair structures are associated mostly with straighter Asian hair, whilst elliptical or very elliptical hair fibre is associated with wavier Caucasian and curlier African hair types respectively (Vogt et al., 2008). William Ripley, in his 1898 study: The Racial Geography of Europe famously utilised this classificatory technique to differentiate and organise a cultural hierarchy among European populations according to the characteristics of the body: ...
Article
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This paper extends discussions of the geographies of the body by examining hair as a geographical lens that reimagines the body’s borders. Hair is a key agent in producing and representing the body, specifically through the presences and absences of hair that influence, disturb, transform and transcend its margins. By examining the materialities, performances and discourses associated with how and where hair is situated (or not) on the body, this paper situates hair as a geographical prism that explores new frontiers of the bordered body, shapes corporeal understandings of appearance and projects identities and power well beyond its physical limits.
... while terminal hair is coarse, thick, and usually pigmented. 17,18 Scalp leukotrichia was considered due to vitiligo and not canities in cases with: 1. Leukotrichic hair within vitiliginous scalp 2. Grouped leukotrichic hair with all hairs arising from a single hair follicle. ...
Article
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Background: Leukotrichia has been considered a predictor of poor outcome in vitiligo. However, studies considering the different clinical aspects of leukotrichia in vitiligo patients are few. Aim: Our aim was to conduct a detailed clinical study to provide insights into the relevance and associations of leukotrichia in non-segmental vitiligo. Methods: In this cross-sectional study, vitiligo patients attending the dermatology outpatient clinic and phototherapy unit at Cairo University Hospital over a period of 6 months (April–September 2016) were included. Family history, clinical details, the Vitiligo Global Issues Consensus Conference classification, the Dermatology Life Quality Index, Vitiligo Area and Severity Index, Vitiligo Extent Score, Vitiligo Disease Activity Score and Vellus Score were determined and these measurements were correlated to leukotrichia. Results: Out of the 101 patients studied, leukotrichia was found in 47 (46.5%) patients, with vellus hair involved in 37 (78.7%), terminal hairs in 30 (63.8%) and both in 20 (42.5%) patients. Vellus hair involvement was significantly higher in generalized bilaterally symmetrical vitiligo than in acrofacial or unclassified vitiligo. The incidence of scalp leukotrichia also was higher in generalized symmetrical vitiligo than in acrofacial vitiligo. The Vellus Score showed significant associations with Vitiligo Area and Severity Index, Vitiligo Extent Score and the Dermatology Life Quality Index. Limitations: This was a short-term study with a small sample size. Prognostic and therapeutic correlations were not studied; prospective longitudinal studies are needed for further evaluation. Conclusion: Leukotrichia was found in almost half of the studied sample and its frequency varied among the different types of vitiligo.
... Back to the "several factors" mentioned earlier, the information available in the literature concerning the rates of the hair growth is regrettably scanty. Vogt et al. [16] report that scalp and beard hairs grow at roughly the same rate (0.35 and 0.38 mm/day, respectively), while eyebrows grow more slowly (0.16 mm/day). Racial differences have been described [17] and, indeed, in Japanese, the growth rate on the vertex (0.44 mm/day) is higher than on the temporal area (0.39 mm/day) and, in general, than in Caucasians. ...
... [68][69][70] In humans, the anagen:telogen ratio also changes with age, though the fluctuations are less extreme as compared to rodents given the mosaic pattern of hair cycling. 71,72 The first hair growth phase in humans typically occurs in utero comprised of lanugo hair, 73 though in principle, this may also have an impact on the developing immune system and tolerance promotion. 74 Unfortunately, very little is known with regards to differences between rodents and humans in the molecular regulation of IP at the level of individual HFs. ...
Article
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Anagen stage hair follicles (HFs) exhibit “immune privilege (IP)” from the level of the bulge downwards to the bulb. Both passive and active IP mechanisms protect HFs from physiologically undesired immune responses and limit immune surveillance. IP is relative, not absolute, and is primarily based on absent, or greatly reduced, intra‐follicular antigen presentation via MHC class I and II molecules, along with prominent expression of “no danger” signals like CD200, and the creation of an immuno‐inhibitory signaling milieu generated by the secretory activities of HFs. Perifollicular mast cells, Tregs, and other cells may also contribute to HF IP maintenance in healthy human skin. Collapse of anagen hair bulb IP is an essential prerequisite for the development of alopecia areata (AA). In AA, lesional HFs are rapidly infiltrated by NKG2D+ T‐lymphocytes and natural killer (NK) cells, while perifollicular mast cells acquire a profoundly pro‐inflammatory phenotype and interact with autoreactive CD8+ T cells. Using animal models, significant functional evidence has accumulated that demonstrates the dominance of the immune system in AA pathogenesis. Purified CD4+, CD8+, and NK cell populations, which secrete IFNg, have each been shown to be able to induce AA, whereas Tregs and iNKT cells may provide relative protection against AA development. While IP collapse may be induced by exogenous agents, inherent IP deficiencies might confer increased susceptibility to AA for some individuals. Thus, a key goal for effective AA management is the re‐establishment of a functional HF IP, which may also provide superior protection from disease relapse.
... [8] However, Rakowska defines terminal hair as ≥55 μm wide and uniform in thickness and color, and vellus hair as hypopigmented, nonmedullated, <30 μm thick, and <2-3 mm long. [5,9] In a study by Barth et al., video dermoscopy showed the presence of WTH in 20% of the newborns. These hairs measured 0.04 mm in diameter and 2 cm in length, which is not consistent with either vellus At birth, there are two consecutive waves of hair from the forehead to nape of the neck with the newer wave consisting only of anagen roots, and the previous wave converting to telogen prior to being shed. ...
Article
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Objective: The aim of the study is to establish normal values of measurable parameters, set the standard, and provide a framework for future reference. Materials and methods: A total of 750 children of Malayalam speaking ethnicity with no hair or scalp diseases in anamnesis and clinical examination were included in the study. Children were divided into six age groups (neonates, infants, 1-5, 6-10, 11-14, and 15-17 years), and trichoscopy was performed in frontal, left and right temporal, vertex, crown, and occiput using Wi-Fi cordless digital dermoscope. Hair shaft, follicular opening, and perifollicular and interfollicular area were evaluated and analyzed with SPSS software. Results: Among the parameters analyzed, we observed that with 0.95 probability (95%), the terminal: vellus ratios are (26,29), (22,25), (22,26), (29,33), (25,29), and (19,24) in neonates; (11,14), (7,11), (9,13), (13,17), (12,16), and (7,12) in infants; (16,17), (10,11), (10,11), (16,18), (15,16), and (14,15) in 1-5 years; (17,18), (11), (11), (19,21), (23), and (16,17) in 6-10 years; (17,18), (9,10), (10), (19,20), (18,19), and (16,17) in 11-14 years; and (14,15), (8-9), (8,9), (15,16), (14, 16), and (13,14) in 15-17 years. Likewise, we have documented the various trichoscopic findings of different age groups. Conclusion: We propose the summary of trichoscopic patterns of different age groups with normal hair and scalp to accurately identify the abnormal.
... 16 In our study, PEGDA hydrogels patterned with 200 μm microwells were fabricated as the diameter of the hair bulb was shown to be around 150-200 μm from histological images. 18 Herein this study, we introduce a systematic approach for producing 3D core-shell heterotypic spheroids of controlled sizes by the sequential seeding of dissociated human DP cells, keratinocytes and HDF cells into microarray hydrogels fabricated from PEGDA using soft photolithography. Preparing the heterotypic spheroids in this way restores the spatial orientation of these cells in order to investigate the effects on their cell compartmentalization. ...
Article
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Objectives: Reproducing human hair follicles in vitro is often limited by various reasons such as the lack of a systematic approach to culture distinct hair follicle cell types to reproduce their spatial relationship. Here, we reproduce hair follicle-like constructs resembling the spatial orientation of different cells in vivo, to study the role of keratinocytes in maintaining cellular compartmentalization among hair follicle-related cells. Materials and methods: Dermal papilla (DP) cells, HaCaT keratinocytes and human dermal fibroblast (HDF) cells were seeded sequentially into three-dimensional (3D) microwells fabricated from polyethylene glycol diacrylate hydrogels. Quantitative polymerase chain reaction was used to compare inductive gene expression of 3D and two-dimensional (2D) DP. DP and HaCaT cells were transfected with green fluorescent protein and red fluorescent protein lentivirus, respectively, to enable cell visualization using confocal microscopy. Results: The 3D DP cultures showed significantly enhanced expression of essential DP genes as compared 2D cultures. Core-shell configurations containing keratinocytes forming the outer shell and DP forming the core were observed. Migratory polarization was mediated by cell-cell interaction between the keratinocytes and HDF cells, while preserving the aggregated state of the DP cells. Conclusions: Keratinocytes may play a role in maintaining compartmentalization between the DP and the surrounding HDF residing in the dermis, and therefore maintains the aggregative state of the DP cells, necessary for hair follicle development and function.
... Similar to other precocial mammals, GCR offspring are born with their eyes opened and hairs on the body (Opara, 2010). Interestingly, we found that eyelid development (as assessed by the time between eyelid fusion and separation) appears faster in the pre-natal GCR, in which it covers about 20% of total gestation length (30 of 150 days), when compared to that of human, in which it covers about 30% (84 of 280 days), and sheep, in which it covers about 33% of total gestation length (50 of 150 days) Tawfik, Abdulhafez, Fouad, & Dutton, 2016 (Bolla, Jasmin, Monteil, & Loubiere, 1991;Hill, 2019c;Lyne & Hollis, 1972;Sivachelvan et al., 1996;Vogt, McElwee, & Blume-Peytavi, 2008 The anogenital distance was computed as the distance between the genital tubercle (A) and anal opening (B). Scale bars represent 0.5 cm. ...
Article
The Greater cane rat (GCR, Thyronomys swinderianus) is a precocial rodent predominantly found within Africa. Economic and scientific interests have led to several research efforts towards the domestication and better understanding of the biology and development of this rodent. Despite these efforts, information on the pre‐natal development of this rodent is currently lacking. This study characterises distinct developmental milestones including skin pigmentation, emergence and distributions of hairs, calvarium consistency, teeth eruption, development of appendages, sensory organs and external genitalia in the pre‐natal GCR and assesses quantitative body parameters, that is body weight, body and crown–rump lengths across its entire gestation length (gestation days [GDs] 10‐140). Using these external features, we provide baseline reference ontogenetic scales for GCR embryos and fetuses, employable for stage, age and sex estimation of the pre‐natal GCR in future studies. We observed that the first evidence of an embryo was not seen before the end of the first trimester (GD50) and that the late second trimester (GD80‐GD100) marks the transition from embryogenesis to fetogenesis in the GCR. As both events occur at a much later developmental time point when compared to precocial non‐rodents including human, sheep and pig and slightly later when compared to other precocial rodents such as guinea pig, our data provide first indication that the pre‐natal GCR development might be associated with a reproductive delay. Together, this study expands our knowledge of the development and biology of the GCR, which will improve reproductive and breeding management, and native species conservation of this hystricomorph mammal.
... The curved shape of the hair follicle is responsible for the curly, spiral or helical nature of the African hair. [12][13][14] After a close shave, emerging sharp-tipped hairs from the follicle grow downwards or parallel to the skin and penetrate the skin a few millimeters away from the follicle, known as extra-follicular penetration ( Figure 1A, B). The penetration of the epidermis by the hair shaft causes invagination of the epidermis simulating a follicle hence the name "pseudofollicle". ...
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Adebola Ogunbiyi Department of Medicine, University College Hospital, Ibadan, Oyo State, Nigeria Abstract: Pseudofolliculitis barbae (PFB) is a chronic inflammatory disorder of follicular and peri-follicular skin characterized by papules, pustules, and post-inflammatory hyperpigmentation. It occurs more frequently in men of African and Asian descent. The etiology of PFB is multifactorial. Shaving or plucking the hair precipitates the onset of an inflammatory reaction that results from the penetration of the adjacent skin by the growing sharp tips. The curved shape of the hair follicle allows for the downward curvature and penetration of the growing hair tips into the skin. The onset of the foreign body reaction leads to itching and the development of papules, pustules, and post-inflammatory hyperpigmentation, especially in the beard area although other shaved areas of the body may be affected. Keloids have also been known to develop after the onset of PFB, giving rise to extensive unsightly scars. Diagnosis is clinical. Cessation of shaving or removal of the involved hair follicles usually terminates the development of PFB. Individuals with the single nucleotide substitution in the hair follicle companion layer specific keratin gene (K6hf) have a six fold increased chance of developing PFB. Keywords: pseudofolliculitis barbae, pathogenesis, treatment
Article
Trichoscopy (or dermoscopy of hair and scalp) is an easy in-office technique that may be performed with a handheld dermoscope or a digital videodermoscopy system. This method is gaining increasing popularity, because it may be applied in differential diagnosis of multiple hair and scalp diseases. The focus of this article is application of trichoscopy in differential diagnosis of the most frequent hair and scalp diseases in dermatologic practice. Trichoscopy of genetic hair shaft abnormalities are briefly addressed. A new classification of perifollicular and interfollicular skin surface abnormalities is proposed.
Article
AIMS: Analysis of ethyl glucuronide (EtG), a minor metabolite of ethanol, is a valid tool for the assessment of social and chronic excessive alcohol consumption. Standardized analysis of EtG is usually done in head hair. As head hair cannot always be provided, alternative hair matrices become more and more interesting. Therefore, a study was performed that compared the intra-individual EtG concentrations in scalp hair and non-head hair (chest, arm, leg and axillary hair). METHODS: Hair samples were collected from 68 subjects undergoing an expert assessment for fitness to drive. Aqueous extracts of the hair matrix were cleaned by solid-phase extraction, using an Oasis MAX column. EtG was first derivatized with perfluoropentanoic anhydride and then quantified by GC-MS/MS in negative chemical ionization mode, using EtG-d5 as internal standard. RESULTS: For categorizing drinking behaviour, the two EtG cut-off values recommended by the Society of Hair Testing were applied for all different hair types. For chest, arm and leg hair, correct classification ratios were >83%. This corresponds to sensitivity values >78% and specificities >75%. Such values indicate together with ϕ coefficients (rϕ) > 0.7 a high correlation of the categorization of the drinking behaviour based on these body hair EtG concentrations compared with the indexing based on scalp hair EtG-values. However, it must be taken into consideration that the time frame represented by non-head hair may extend way back. CONCLUSIONS: These results indicate that chest, arm and leg hair can be a valid alternative to assess the drinking behaviour of a subject if head hair is not available; whereas axillary hair is not suitable as alternative matrix.
Article
Trichoscopy (hair and scalp dermoscopy) analyzes the structure and size of growing hair shafts, providing diagnostic clues for inherited and acquired causes of hair loss. Types of hair shaft abnormalities observed include exclamation mark hairs (alopecia areata, trichotillomania, chemotherapy-induced alopecia), Pohl-Pinkus constrictions (alopecia areata, chemotherapy-induced alopecia, blood loss, malnutrition), comma hairs (tinea capitis), corkscrew hairs (tinea capitis), coiled hairs (trichotillomania), flame hairs (trichotillomania), and tulip hairs (in trichotillomania, alopecia areata). Trichoscopy allows differential diagnosis of most genetic hair shaft disorders. This article proposes a classification of hair shaft abnormalities observed by trichoscopy.
Article
Diseases of the periocular hair range from localized disease to systemic processes and may present challenging diagnostic questions. We present a comprehensive clinical guide to the evaluation and diagnosis of these disorders. Deficiencies in growth, excess production, changes in pigmentation, aberrant position, or abnormalities in form may affect this region's hair. These range from benign to sight-, and even life-, threatening pathologies. (Surv Ophthalmol 56:416-432, 2011. (C) 2011 Elsevier Inc. All rights reserved.)
Article
Identifying criminals and victims in images (e.g., child pornography and masked gunmen) can be a challenging task, especially when neither their faces nor tattoos are observable. Skin mark patterns and blood vessel patterns are recently proposed to address this problem. However, they are invisible in low-resolution images and dense androgenic hair can cover them completely. Medical research results have implied that androgenic hair patterns are a stable biometric trait and have potential to overcome the weaknesses of skin mark patterns and blood vessel patterns. To the best of our knowledge, no one has studied androgenic hair patterns for criminal and victim identification before. This paper aims to study matching performance of androgenic hair patterns in low-resolution images. An algorithm designed for this paper uses Gabor filters to compute orientation fields of androgenic hair patterns, histograms on a dynamic grid system to describe their local orientation fields, and the blockwise Chi-square distance to measure the dissimilarity between two patterns. The 4552 images from 283 different legs with resolutions of 25, 18.75, 12.5, and 6.25 dpi were examined. The experimental results indicate that androgenic hair patterns even in low-resolution images are an effective biometric trait and the proposed Gabor orientation histograms are comparable with other well-known texture recognition methods, including local binary patterns, local Gabor binary patterns, and histograms of oriented gradients.
Article
The aim of this study was to evaluate by clinical and noninvasive instr umental evaluations the efficacy and tolerance of a cosmetic topi cal slimming treatment specific for light/moderate adipose pannicula at the level of the waist and hips. The protocol was per formed as a double-blind active vs placebo trial in 110 volunteers for a period of 4 weeks, with an additional visit 4 weeks after the last product applica tion. The following clinical/instr umental evaluation was per formed during the visit: clinical assessment of hip-abdomen adipose pannicula, circumference measurements, ultrasonographic evaluation of adipose pannicula thickness, and plicometr y. At the end of treatment, the slimming activity of the study product resulted in clinically different results than placebo, determined by a significant decrease in abdomen/ hips circumferences and considerable reduction of abdomen/hips adipose pannicula thickness. The tolerability of the product was good and the enrolled volunteers expressed their full satisfaction with the studied product.
Article
Hair and scalp diseases present an extensive diagnostic and therapeutic task. Treating them is often a challenge for the physician in daily practice. Unclear diagnoses, chronic conditions with long-lasting therapies and the uncertainty of the patient may often lead to unsatisfying situations for both the patient as well as the doctor. The complaints can be divided into (1) hair loss, (2) increased hair growth and (3) abnormal hair quality. A structured history and the objectification of the clinical findings with the help of standardized diagnostic methods and score systems or classifications enable a diagnosis in most patients already at the first visit. Moreover, such structured processes strengthen the treatment satisfaction and compliance of both the patient and the therapist. In the meantime, diagnostic measures and clinical practice guidelines are available for the most common hair disorders. Expertise in basic psychosomatic care and an empathetic approach to the fears and concerns as well as practical advice for the daily contact with hair disorders should be integrated as separate elements in the management of hair diseases; in most cases they are gratefully welcomed by the patients. The aim of this article is to provide the physician with a guideline for the structured management of a hair patient. An overview of recent new developments and the currently available clinical practice guidelines for diagnosis and therapy of hair disorders is presented.
Article
Humans are unique in many respects including being furless, striding bipeds that excel at walking and running long distances in hot conditions. This review summarizes what we do and do not know about the evolution of these characteristics, and how they are related. Although many details remain poorly known, the first hominins (species more closely related to humans than to chimpanzees) apparently diverged from the chimpanzee lineage because of selection for bipedal walking, probably because it improved their ability to forage efficiently. However, because bipedal hominins are necessarily slow runners, early hominins in open habitats likely benefited from improved abilities to dump heat in order to forage safely during times of peak heat when predators were unable to hunt them. Endurance running capabilities evolved later, probably as adaptations for scavenging and then hunting. If so, then there would have been strong selection for heat-loss mechanisms, especially sweating, to persistence hunt, in which hunters combine endurance running and tracking to drive their prey into hyperthermia. As modern humans dispersed into a wide range of habitats over the last few hundred thousand years, recent selection has helped populations cope better with a broader range of locomotor and thermoregulatory challenges, but all humans remain essentially adapted for long distance locomotion rather than speed, and to dump rather than retain heat. © 2015 American Physiological Society. Compr Physiol 5: 99-117, 2015.
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Over the last few decades, recent advances in molecular biology and genetics, as well as the development of new experimental techniques, have brought together scientists from all fields of biological science [1]. Developmental biologists, geneticists, endocrinologists, and dermatologists now study the many diverse facets of hair follicle biology, including neuroectodermal-mesenchymal interactions, immunology, pigmentation, and stem cell biology. Progress in these scientific fields has led to discovering more than 300 genetic diseases, whose clinical picture includes hair follicles disorders. The evaluation of hair growth is a simple, first-rate diagnostic tool in pediatric dermatology and genetics. Identifying hair disorders can also be a useful tool in diagnosing diseases in their early stages before more severe symptoms of progressive multi-organ involvement develop [1, 2].
Article
Dermoscopic examination of hair and scalp, also named "trichoscopy," is an essential tool in diagnosis of hair and scalp diseases. Trichoscopy is fast and noninvasive and can be used to evaluate hair disorders in all body areas. Body hair disorders are uncommon, and most publications on their dermoscopic features are limited to case reports or series. In this review we present the available information on the dermoscopic diagnosis of body hair disorders including keratosis pilaris, trichostasis spinulosa, pili multigemini, circle hairs, rolled hairs, eruptive vellus hair cyst, and ingrown hairs. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.
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Over the past years, hair follicles have gained a lot of interest in the field of skin penetration research as they represent an important penetration pathway for topically applied substances. They function as reservoirs [1, 2] and also as portals of entry to the viable skin layers [3]. Under physiological conditions the intact stratum corneum significantly impairs skin penetration, especially of large hydrophilic molecules and particulate structures. Hair follicles, in contrast, represent interruptions in this barrier and the importance of the transfollicular route of penetration has been demonstrated by several independent studies on various animal skin models, where hairy skin was compared with hair follicle-free skin areas [4, 5]. The role of the follicular penetration pathway compared to transepidermal route was also demonstrated by selective blockage of the follicular orifices in porcine ear skin [6] as well as human skin explants [7]. In vivo experiments with caffeine applied as shampoo formulations on skin with open or sealed hair follicles further underlined the importance of hair follicles for the transdermal permeation and systemic delivery of hydrophilic drugs [8]. The follicular route seems to be of special importance for particle penetration in skin. Particulate structures ranging from liposomes to solid inorganic particles and microspheres up to a diameter of 10 μm were shown to aggregate and remain in hair follicle openings. Such observations provided the basis for the idea of hair follicle targeting with particulate drug carriers [9]. Modifications of nanoparticle physicochemical properties, use of permeabilizing agents, as well as partial removal of the stratum corneum are some of the methods which were shown to increase the hair follicle penetration of drug-loaded nanoparticles as well as their targeting ability [10, 11]. In the following chapter, we outline how hair follicles act as entry pathway and reservoir structure for topically applied particles. We review the penetration properties of specific particle types and the influence of hair follicle parameters, e.g., hair follicle types, growth activity, and sebum production as modifying factors of particle–skin interactions. In fact, studies by our group and others strongly suggest that the hair follicle provides an important interface for such interactions. Nanoparticle-based hair follicle targeting aims at utilizing these interactions for therapeutic purposes, e.g., to deliver functionalized particles loaded with active compounds selectively to the hair follicles or even to specific skin compartments and cell populations. Particle-based targeting of hair follicles may include deposition of active compounds in the follicular reservoir, targeting of active compounds to specific compartments within the follicular duct, e.g., sebaceous gland, stem cell region, or even targeting of specific cell populations such as perifollicular antigen-presenting cells (Fig. 9.1).
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Normal hair shafts are uniform in thickness and color. Trichoscopy allows detection of several hair shaft abnormalities, including various types of fractured hairs, hairs with narrowings, hairs with node-like structures, twisted or curled hairs, hairs with bands, and short hairs. In this chapter, we propose a classification of hair shaft abnormalities that may be detected by trichoscopy.
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In the human body, hair follicles, and hence, the hair shafts that grow from them vary, depending on location, age, and sex. Moreover, each hair follicle may produce different hair types throughout its lifetime [1]: lanugo hair is produced during intrauterine life, vellus hair in childhood and pre-puberty, and terminal hair in adulthood are all produced by the same hair follicle. However, the number and distribution of hair follicles on the human body are both genetically predetermined and remain throughout life [2].
Article
Background Several interactions between retinoids and immune system exist. Current evidences suggest a role of retinoic acid in controlling hair cycle. Retinol-binding protein 4 (RBP4) belongs to the lipocalin family and is the specific carrier for retinol (vitamin A) in the blood. It delivers retinol from the liver stores to the peripheral tissues. The pathogenesis of alopecia areata (AA) may be related to increased serum RBP4 level. Objective To assess the level of RBP4 in patients with AA. Patients and methods This comparative study was conducted on 60 participants who were divided into three groups: group A consisting of 20 patients with active AA; group B consisting of 20 patients with androgenetic alopecia, selected as an example of noninflammatory hair loss; and group C consisting of 20 normal healthy controls. Blood samples were collected from all participants and RBP4 level was measured using enzyme-linked immunosorbent assay. Results RBP4 mean value was found to be 38.37±2.83, 37.27±5.05, and 32.10±2.28 μg/ml for groups A, B, and C, respectively. Healthy control group had statistically significant lower value of RBP4 than did the other two groups, but there were no significant difference between AA patients and androgenetic alopecia patients. In AA group, there was no significant relation between number of lesions and the level of RBP4. Conclusion The level of RBP4 was found to be increased in serum of both AA and androgenetic alopecia patients. The role of RBP4 may be as a nonspecific molecule leading to hair loss or miniaturization through controlling hair cycle. However, the exact role of RBP4 in the hair cycle and its clinical significance in treatment of AA remains to be elucidated.
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The word hair usually refers to two distinct structures, hair follicle, the part locates in the dermis, and the hair shaft, which is the hard filamentous part that extends above the skin surface and varies with ethnicity in diameter and format. The hair shaft can be modified with different cosmetic procedures and also can be damage during the process. This chapter will approach hair anatomy, structure of hair shaft, hair damage, hair analyses, and different ways to process hair changes.
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Trichoscopy (hair and scalp dermoscopy) is a novel method of noninvasive skin imaging that may be applied in diagnosing hair and scalp diseases. The method may also be used for quantitative evaluation and monitoring of hair loss in dermatological practice and in clinical trials. A rough semiquantitative estimation of trichoscopy features may be obtained with a handheld dermoscope and is sufficient for clinical practice. For research purposes and clinical trials, it is preferable to obtain digital photographs of the visualized area.
Article
p class="abstract"> Anagen effluvium occurs due to an agent or event that drastically reduces the metabolic activity of the matrix cells of the hair follicle. At any given time more than 80% of scalp hair is in the anagen phase of the hair cycle. Hence the resulting hair loss is abrupt and extensive. In majority of the cases, it occurs in association with cancer chemotherapy and radiation, other causes being rare. Here we report a case of a middle aged female suffering from Atopic dermatitis that was put on treatment with Azathioprine for the same. Treatment with Azathioprine was followed by a diffuse and extensive hair loss from the scalp associated with painful oral ulcers and marked leucocytopenia within a month of administration. The hair grew back within four months of stopping Azathioprine. This case report is an attempt to highlight a rare but extremely distressing side effect of Azathioprine which is a commonly used drug in dermatology. </p
Chapter
The word hair usually refers to two distinct structures, hair follicle, the part locates in the dermis, and the hair shaft, which is the hard filamentous part that extends above the skin surface and varies with ethnicity in diameter and format. The hair shaft can be modified with different cosmetic procedures and also can be damage during the process. This chapter will approach hair anatomy, structure of hair shaft, hair damage, hair analyses, and different ways to process hair changes.
Article
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The hair follicle is an organ in the human skin. This organ consists of about 20 cell types. Hair follicles regulate hair growth with hormones, neuroproteins, and immune cells. This complex interaction leads to the production of different hair by hair follicles seen on different parts of the body. The stages of hair growth are: Anagen (active growth stage), Catagen (rest stage), Telogen (regression phase of the hair follicle), Exogen (active phase of hair erosion), and finally Kenogen (the time between hair follicle being empty and new hair growth) (1). The hair follicle includes hair roots and sebaceous glands. This structure inside the skin has a certain biochemistry, metabolism, and immunology. Recent studies have focused on hair follicles as a potential route for delivery of topical and systemic drugs (2). Drug delivery through hair follicles is very important because it has optimal effects on the delivery of topical medications. These follicles are enclosed by capillaries, antigen-containing cells, sebaceous glands, and stem cells in the extremity of the hair follicles (3). Hair follicles and sebaceous glands can be specific pathways for the passage of certain molecules or formulations that enter the site of effect or blood faster than the stratum corneum (4). The immunological environment of the hair follicles has recently been addressed by researchers in the field of transfollicular delivery, in particular for the development of active immune function without needle insertion. Hair follicles may facilitate the absorption of large molecules or hydrophilic molecules, such as vaccine antigens. Nanotechnology may facilitate transfollicular in various ways, as nanoparticles penetrate more in hair follicles. Also, nanoencapsulation can stabilize the antigens and increase their antigenicities. It seems that only a limited portion of the antigen should be available locally through the hair follicles (5). The use of formulations, such as foam, can also increase the absorption of drugs by transfollicular treatment. A study on the absorption of minoxidil showed that minoxidil foam brings the drug through the hair follicle better than the stratum corneum pathway. This study suggests that higher absorption from the follicular route is due to the presence of a dense network of hair follicles by a dense network of blood capillaries, dendritic cells and stem cells, which is very suitable for drug delivery (6). Many studies have shown that drug permeation with a microemulsion formulation may be increased by trans-follicular administration (7). Microemulsions are transparent semi-solid drug delivery systems with high hermo-dynamic stability, which include isotropic liquid, oil, water and surfactant mixtures, usually combined with a carbohydrate compound (8, 9). The particle size of the dispersed phase in a microemulsion is less than 100 nm. Microemulsions primarily increase drug local absorption (10-12). Trans-follicular transfusion adapalene examination shows that microemulsions penetrates through hair follicles and is suitable for delivery of a transfollicular drug (7). Liposomes have been used extensively for drug delivery in several studies. Studies have shown that liposomes have a greater penetration in the hair follicle than simple pharmaceutical forms. Liposomes exhibited greater penetration depth than standard formulas. The relative penetration depth used in the standard formula was 30% on average, while liposomal formulations mainly penetrated to a greater depth of hair follicles. Amphoteric and cationic liposomes reach a depth of relative penetration of about 70% of the length of the full hair follicle (13). Transfollicular drug delivery can greatly affect the absorption of steroid drugs. A research showed that this drug delivery method can greatly affect the permeation of drugs, such as hormonal drugs and corticosteroids (14). In a study that compared the absorption of drugs from the scalp and abdomen, the results showed that the scalp could be significantly more suitable for the delivery of hydrophilic and lipophilic drugs than abdominal skin. Histological examination of the skin after using the formulation shows that the probe penetrates the site of the skin and follicles (15). The rate of absorption of caffeine can be greatly increased by crossing the trans-follicular pathway (16). Various absorption enhancers can also greatly enhance the permeability of the drug through the hair follicle. Therefore, the use of oleic acid and eucalyptus increased the absorption of caffeine up to four times, while maintaining caffeine in stratum corneum was the same in all cases. The researchers found that the optimal formulation of drug delivery through the transfollicular route can also be used as absorption enhancers (17). The findings of the review of transfollicular drug delivery suggest that this drug delivery pathway can be a good route to replace other methods. Formulations used in studies, such as liposome, micro-emulsion, foam and etc. somewhat respond to this pathway more appropriately.
Article
Previous genetic studies on hair morphology focused on the overall morphology of the hair using data collected by self-report or researcher observation. Here, we present the first genome-wide association study (GWAS) of a micro-level quantitative measure of hair curvature. We compare these results to GWAS results obtained using a macro-level classification of observable hair curvature performed in the same sample of twins and siblings of European descent. Observational data were collected by trained observers, while quantitative data were acquired using an Optical Fibre Diameter Analyser (OFDA). The GWAS for both the observational and quantitative measures of hair curvature resulted in genome-wide significant signals at chromosome 1q21.3 close to the trichohyalin ( TCHH ) gene, previously shown to harbor variants associated with straight hair morphology in Europeans. All genetic variants reaching genome-wide significance for both GWAS (quantitative measure lead single-nucleotide polymorphism [SNP] rs12130862, p = 9.5 × 10 –09 ; observational measure lead SNP rs11803731, p = 2.1 × 10 –17 ) were in moderate to very high linkage disequilibrium (LD) with each other (minimum r 2 = .45), indicating they represent the same genetic locus. Conditional analyses confirmed the presence of only one signal associated with each measure at this locus. Results from the quantitative measures reconfirmed the accuracy of observational measures.
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Full-text available
Introduction: Many procedures are performed on the scalp, such as excision of pilar and sebaceous cysts, melanocytic nevi, and reduction surgery for scarring alopecia, among others. In hair transplants, telogen effluvium is often reported 3 months after surgery; however, hair loss usually happens much earlier, around second week after the procedure, not compatible with the time required for hair to enter telogen and exogenous phases in normal conditions. Case reports: We report 3 cases of anagen hair loss 4 weeks after surgeries, with perilesional trichoscopy suggesting anagen effluvium, with typical signs such as black dots and exclamation hairs. Discussion: There are only a few reports about hair loss around operated areas. The cause of this postoperative anagen effluvium is probably a transient ischemia. Conclusion: The practical importance of this phenomenon is to properly orient patients because most of the hair will be lost, since 85% of them are anagens, and also will have spontaneous recovery in the next 3 months.
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A dermoscope used to diagnose hair and scalp disorders is called a trichoscope. Approach to trichology is based on clinical expertise of the dermatologist and investigative techniques. Trichoscopy is a valuable asset in clinical practice as it simplifies diagnosis of common trichological conditions with similar presentations. It not only highlights the subtle trichoscopic points invisible to the naked eye but also serves as a prognostic and monitoring tool in therapeutic management. Trichoscopy goes a long way in improving the diagnostic and clinical acumen of the physician. Trichoscopic language deals with pattern analysis ranging from hair shaft patterns to follicular, perifollicular, and interfollicular patterns. This section on trichoscopy not only describes the key trichoscopic features of non-cicatricial alopecias and cicatricial alopecias but also helps to delineate various trichological mimics from each other. It highlights various trichoscopic points of genetic hair shaft disorders and pediatric trichological conditions.
Article
The important role of hair follicles as penetration pathways and reservoir structures for topically applied compounds has been validated in numerous animal models as well as in humans. Follicular penetration rates are modulated by regional variations in size and proportions and the functional status. Advances have especially been made in the targeting of hair follicle-associated cell populations including antigen-presenting cells and stem cells. Improved investigative methods based on differential stripping, spectrophotometry and confocal laser scanning microscopy have led to the determination of the penetration profiles and kinetics for a multiplicity of drugs and drug delivery systems. The observation that particulate delivery systems aggregate and remain in hair follicle openings and their penetration along the follicular duct occurs in a size-dependent manner, which has led to advanced concepts of targeted drug delivery of bioactive compounds in the field of solid particles, as well as semi-solid particles, such as liposomes. This review summarizes the recent progress in this field, and underlines the necessity for pilot studies in human volunteers to further the development of clinical applications for follicular targeting.
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Hair disorders have become a central social and psychological issue with increasing demands and expectations from patients. Written by world-renowned experts, this lavishly illustrated textbook provides the latest scientific aspects of hair biology, up-to-date knowledge on hair diagnosis and treatment options as well as hair removal and restoration techniques. The well-structured content is divided into three sections: * Basic aspects of hair growth * Hair and scalp disorders * Fotoepilation, surgery and hair cosmetics It also contains unique sections on hair at different ages, in art and in forensic investigations as well as ethnic hair.