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Hair Cycle (hair + cycle)

Distribution by Scientific Domains

Medical Sciences	72%
Life Sciences	27%

Selected Abstracts

Enhancing the Growth of Natural Eyelashes: The Mechanism of Bimatoprost-Induced Eyelash Growth

DERMATOLOGIC SURGERY, Issue 9 2010
2Article first published online: 2 APR 2010, JOEL L. COHEN MD
BACKGROUND Many women desire prominent eyelashes. In December 2008, bimatoprost ophthalmic solution 0.03% was approved for the treatment of hypotrichosis of the eyelashes in the United States. OBJECTIVE To review eyelash physiology and the proposed mechanisms by which the topical pros-tamide product bimatoprost enhances eyelash growth. METHODS AND MATERIALS Clinical and preclinical studies pertaining to the efficacy, safety, and mechanisms of action of bimatoprost are presented. RESULTS Treatment with bimatoprost increases the percentage of eyelash follicles in anagen at any one time. This probably accounts for its ability to lengthen lashes. Bimatoprost-induced stimulation of melanogenesis appears to result in darker lashes and, at the same time, appears to increase the size of the dermal papilla and hair bulb, affecting lash thickness and fullness. Such effects, largely demonstrated in animal studies, are consistent with the results of a recent Food and Drug Administration phase III clinical trial. The favorable safety profile of bimatoprost in human subjects is probably secondary to the limited exposure of ocular tissues resulting from topical application at the base of the upper lashes. CONCLUSION By influencing the eyelash hair cycle and follicles, bimatoprost ophthalmic solution 0.03% is a safe and effective means of enhancing eyelash growth. Dr. Cohen has served as a consultant and clinical trial participant for Allergan, Inc. [source]

Paradoxical Hypertrichosis After Laser Therapy: A Review

DERMATOLOGIC SURGERY, Issue 3 2010
SHRADDHA DESAI MD
BACKGROUND Laser hair removal is a safe and effective procedure for the treatment of unwanted body hair but is not exempt from side effects. A rare but significant adverse effect with this treatment modality is paradoxical hypertrichosis. OBJECTIVE To evaluate the potential etiologies, risk factors, related laser types, and treatment options for the development of excess hair after laser therapy. MATERIALS AND METHODS An analysis of previously published case studies and review articles along with our own experience was used to gather information regarding this phenomenon. RESULTS Paradoxical hypertrichosis has a low incidence, ranging from 0.6% to 10%, and most commonly occurs on the face and neck. All laser and light sources have the potential to cause hair induction, especially in individuals with darker skin types (III,VI); with dark, thick hair; and with underlying hormonal conditions. Possible causes include the effect of inflammatory mediators and subtherapeutic thermal injury causing induction of the hair cycle. Treatment for paradoxical hypertrichosis is laser therapy of the affected area. CONCLUSIONS Paradoxical hypertrichosis is a rare side effect of laser hair removal; the pathogenesis of this event remains widely unknown. We recommend further large-scale studies to investigate this effect. The authors have indicated no significant interest with commercial supporters. [source]

Embryonic dermal condensation and adult dermal papilla induce hair follicles in adult glabrous epidermis through different mechanisms

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 2 2006
Mutsumi Inamatsu
Hair induction in the adult glabrous epidermis by the embryonic dermis was compared with that by the adult dermis. Recombinant skin, composed of the adult sole epidermis and the embryonic dermis containing dermal condensations (DC), was transplanted onto the back of nude mice. The epidermis of transplants formed hairs. Histology on the induction process demonstrated the formation of placode-like tissues, indicating that the transplant produces hair follicles through a mechanism similar to that underlying hair follicle development in the embryonic skin. An isolated adult rat sole skin piece, inserted with either an aggregate of cultured dermal papilla (DP) cells or an intact DP between its epidermis and dermis, was similarly transplanted. The transplant produced hair follicles. Histology showed that the epidermis in both cases surrounded the aggregates of DP cells. The epidermis never formed placode-like tissues. Thus, it was concluded that the adult epidermal cells recapitulate the embryonic process of hair follicle development when exposed to DC, whereas they get directly into the anagen of the hair cycle when exposed to DP. The expression pattern of Edar and Shh genes, and P-cadherin protein during the hair follicle development in the two types of transplants supported the above conclusion. [source]

Runx3 is involved in hair shape determination

DEVELOPMENTAL DYNAMICS, Issue 4 2005
Eli Raveh
Abstract Transcriptional regulators of the Runx family play critical roles in normal organ development and, when mutated, lead to genetic diseases and cancer. Runx3 functions during cell lineage decisions in thymopoiesis and neurogenesis and mediates transforming growth factor-, signaling in dendritic cells. Here, we study the function of Runx3 in the skin and its appendages, primarily the hair follicle, during mouse development. Runx3 is expressed predominantly in the dermal compartment of the hair follicles as they form and during the hair cycle, as well as in the nail and sweat gland skin appendages. Distinct expression is also detected periodically in isolated cells of the epidermis and in melanocytes, populating the hair bulb. Runx3 -deficient mice display a perturbation of the normal hair coat, which we show to be due to hair type and hair shape changes. Thus, one of the functions of Runx3 in skin may be to regulate the formation of the epithelial derived structural hair by affecting dermal to epidermal interactions. Developmental Dynamics 233:1478,1487, 2005. © 2005 Wiley-Liss, Inc. [source]

Foot shock stress prolongs the telogen stage of the spontaneous hair cycle in a non-depilated mouse model

EXPERIMENTAL DERMATOLOGY, Issue 7 2007
Mirei Katayama
Abstract:, Background:, There is an increasing evidence to indicate that stress can influence skin disease and cutaneous functions. Previous studies have shown that stress alters the murine hair cycle; however, these studies have been carried out by using mouse models in which the hair cycle is forcibly synchronized after depilation. Objective:, To examine whether foot shock stress (FS) changes the spontaneous hair cycle in a non-depilated animal model, and to evaluate the role of mast cells and substance P (SP) in the influence of stress on the hair cycle. Methods:, Changes in the spontaneous hair cycle and the inhibitory effects of a specific SP NK1 receptor antagonist were examined in non-depilated mice during 3,4 weeks of FS. Results:, Foot shock stress prolonged the telogen stage of the hair cycle and delayed the induction of the subsequent anagen stage in the animal model. FS caused an increase in the ratio of de-granulated mast cells in the skin, an increase in the number of TUNEL-positive cells, and a decrease in the number of Ki67-positive cells. The NK1 receptor antagonist, WIN 62577, inhibited these stress responses. Conclusion:, Our results strongly support previous work, demonstrating that stress alters active hair-cycling in vivo through the action of SP. [source]

Immunoreactivity of corticotropin-releasing hormone, adrenocorticotropic hormone and , -melanocyte-stimulating hormone in alopecia areata

EXPERIMENTAL DERMATOLOGY, Issue 7 2006
Hei Sung Kim
Abstract:, Psychological factors are believed to play a role in the pathogenesis of alopecia areata (AA), a frequently encountered hair disorder. In our study, statistically significant elevation of psychological stress was felt by AA patients prior hair loss compared with control, which was strongly believed contributory to hair loss (t -test, P < 0.01). The corticotropin-releasing hormone (CRH) and proopiomelanocortin (POMC) mRNA have been identified in the basal layer of the epidermis and pilosebaceous units of the normal scalp. And with the recent discovery of melanocytes and dermal fibroblasts capable of corticosterone production, the presence of a local stress response system resembling the hypothalamic,pituitary,adrenal (HPA) axis has been suggested. The local stress response system is involved in regulation of the normal hair cycle, but its precise role in AA is unknown. The influence of a local HPA axis or rather, CRH,POMC axis in AA was investigated by analysing immunohistochemically the expression levels of CRH and POMC peptides, including the adrenocorticotropic hormone (ACTH) and , -melanocyte-stimulating hormone (, -MSH), in a number of AA lesions and normal scalp (as control). The epidermis and pilosebaceous units of normal scalp stained weakly with CRH, ACTH and , -MSH, whereas those from the affected sites of the AA group showed intense expression of the peptides (chi-square test, P < 0.01). The meaning of this enhanced expression and their role in the pathogenesis of AA should be further evaluated in future. [source]

Decapeptide with fibroblast growth factor (FGF)-5 partial sequence inhibits hair growth suppressing activity of FGF-5

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2003
Chikako Ito
Earlier studies demonstrated that knock-out of fibroblast growth factor-5 gene (Fgf-5) prolonged anagen VI phase of hair cycle, resulting long hairs in the mice. We showed the activities on hair growth of the two Fgf-5 gene products, one of which, FGF-5 suppressed hair growth by inhibiting anagen proceeding and inducing the transition from anagen to catagen, and FGF-5S, a shorter polypeptide with FGF-5-antagonizing activity translated from alternatively spliced mRNA, suppressed this activity of FGF-5. As the results suggested that FGF-5 antagonist would increase hair growth, we synthesized various peptides having partial sequences of human FGF-5 and FGF-5S and determined their FGF-5 antagonist activity. Among them, a decapeptide designated P3 (95-VGIGFHLQIY-104) that aligns with receptor binding sites of FGF-1 and FGF-2 suppressed FGF-5-induced proliferation of BALB/3T3 A31 and NIH/3T3 murine fibroblasts, and FGF receptor-1c (FGFR-1c)-transfected Ba/F3 cell line (FR-Ba/F3 cells). IC50s of this peptide on these cell proliferations were 64, 28, 146 ,M, respectively. On the other hand, IC50 of this peptide on binding of FGF-5 to the FGFR-1(IIIc)/Fc chimera was 483 ,M. Examination in dorsal depilated mice revealed that the P3 peptide reduced the activity of FGF-5 to recover hair pigmentation and hair follicle lengths. The classification of histologically observed skin sections showed FGF-5-induced delations of anagen procedure had reduced by the P3 peptide. The anti-Ki67 antibody staining of hair follicles was inhibited by administration of FGF-5, and this inhibition by FGF-5 was recovered by administration of the P3 peptide. The P3 peptide alone did not affect hair follicle length and hair cell proliferation. These results indicate that the decapeptide antagonized FGF-5 activity in vivo, and reduced the inhibition of FGF-5 in hair growth, confirming that FGF-5 inhibitors are promising substances against hair loss and/or for promoting hair growth. J. Cell. Physiol. 197: 272,283, 2003. © 2003 Wiley-Liss, Inc. [source]

Temporary hair removal by low fluence photoepilation: Histological study on biopsies and cultured human hair follicles

LASERS IN SURGERY AND MEDICINE, Issue 8 2008
Guido F. Roosen MSc
Abstract Background and Objectives We have recently shown that repeated low fluence photoepilation (LFP) with intense pulsed light (IPL) leads to effective hair removal, which is fully reversible. Contrary to permanent hair removal treatments, LFP does not induce severe damage to the hair follicle. The purpose of the current study is to investigate the impact of LFP on the structure and the physiology of the hair follicle. Study Design/Materials and Methods Single pulses of IPL with a fluence of 9 J/cm2 and duration of 15 milliseconds were applied to one lower leg of 12 female subjects, followed by taking a single biopsy per person, either immediately, or after 3 or 7 days. Additionally, we present a novel approach to examine the effects of LFP, in which ex vivo hairy human scalp skin was exposed to IPL pulses with the same parameters as above, followed by isolation and culturing of the hair follicles over several days. Samples were examined histologically and morphologically. Results The majority of the cultured follicles that had been exposed to LFP treatment showed a marked treatment effect. The melanin containing part of the hair follicle bulb was the target and a catagen-like transformation was observed demonstrating that hair formation had ceased. The other follicles that had been exposed to LFP showed a less strong or no response. The skin biopsies also revealed that the melanin-rich region of the hair follicle bulb matrix was targeted; other parts of the follicle and the skin remained unaffected. Catagen/telogen hair follicles were visible with unusual melanin clumping, indicating this cycle phase was induced by the IPL treatment. Conclusions Low fluence photoepilation targets the pigmented matrix area of the anagen hair follicle bulb, causing a highly localized but mild trauma that interrupts the hair cycle, induces a catagen-like state and eventually leads to temporary loss of the hair. Lesers Surg. Med. 40:520,528, 2008. © 2008 Wiley-Liss, Inc. [source]

Time-specific occurrence of alopecia in neonatal C57BL mice treated with N -methyl- N -nitrosourea and the therapeutic efficacy of tacrolimus hydrate

PATHOLOGY INTERNATIONAL, Issue 3 2000
Katsuhiko Yoshizawa
Abstract Alopecia was induced in male and female neonatal C57BL mice by a single intraperitoneal injection of 60 mg/kg N -methyl- N -nitrosourea (MNU). MNU administration was most effective in the 8-day-old mice and less effective in the 5-day-old mice (at active and early anagen stages of the first hair cycle, respectively). No alopecia was seen in the day 14 MNU-treated animals (at telogen stage of the first hair cycle). MNU effectively induced hair follicular cell apoptosis at the anagen stage by up-regulation of Bax protein without down-modulation of Bcl-2 protein. In day 8 MNU-treated mice, the immunosuppressive agent 0.01% tacrolimus hydrate (FK506), when topically applied for 5 days from 1 day after MNU treatment (before the occurrence of alopecia), decreased the severity of alopecia. However, it did not stimulate hair growth when applied for 5 days from 20 days of age (after occurrence of alopecia). [source]

Ligand-independent Regulation of the hairless Promoter by Vitamin D Receptor,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2008
Andrew Engelhard
The characteristic alopecia associated with mutations in the hairless (hr) and vitamin D receptor (VDR) genes defines the resulting genetic disorders, known as atrichia and VDRRIIa rickets, as phenocopies. In both cases, the separation of the dermal papilla from the regressing hair follicle at the onset of the first catagen phase of the hair cycle and the development of dermal cysts and utricules subsequent to mutation of either gene suggests that their activities affect the same regulatory pathways. VDR functions as a hormonally activated transcription factor, and a role in transcription has been postulated for Hr due in part to its nuclear localization and homology with the GATA-1 zinc-finger domain. Therefore, we examined the hypothesis that VDR and Hr have a direct regulatory effect on each other via a transcriptional mechanism. Ectopic expression of the VDR repressed hr promoter activity in HaCaT cells and primary human keratinocytes (PHKs). While this repression occurs in the absence of 1,25 dihydroxyvitamin D3 (D3), the addition of ligand greatly augments the effect. However, we also demonstrate the rare phenomenon of ligand-independent promoter transactivation by VDR. We show that the full-length promoter is transactivated by VDR in a ligand-independent and cell type-specific manner, suggesting that direct transcriptional regulation of hr by the VDR accounts in part for the phenotypic overlap between atrichia and VDRRIIa rickets. [source]

Dynamic changes in nerve growth factor and substance P in the murine hair cycle induced by depilation

THE JOURNAL OF DERMATOLOGY, Issue 12 2006
Zhanchao ZHOU
ABSTRACT Increasing evidence suggests that various neurotrophins and neuropeptides play an important role in the progression of hair follicle cycling. Among them, nerve growth factor (NGF) and substance P (SP) have attracted special interest recently. However, the interaction between these factors during hair cycling has not yet been systematically studied. We therefore investigated the mutual relationships between NGF and SP and the mechanism by which the anagen stage of the hair cycle is initiated. Fluctuations in numbers of SP-positive nerve fibers and variations in amounts of SP, NGF, and another neurotrophic factor, glial cell-derived neurotrophic factor, in skin in the C57BL/6 mouse depilation-induced hair cycle model, together with the spatiotemporal expression patterns of each of these factors, were followed simultaneously by enzyme-linked immunosorbent assay and immunohistochemistry. The main finding was that a surge in NGF expression and a rapid increase in NGF content in skin is an initial event within 1 day after depilation, followed by elevation of SP content and numbers of SP-containing fibers 2 days after the increase in NGF. Our findings suggest that a rapid and abundant increase in NGF plays a key role in the induction and progression of anagen hair cycling through keratinocyte growth promotion. NGF may also induce plastic changes such as sprouting and hyperplasia in dermal nerve fibers and enhance their SP production. Elevated levels of SP in skin may additionally contribute to the progression of consecutive anagen hair cycles. [source]

Follicular miniaturization in female pattern hair loss: clinicopathological correlations

BRITISH JOURNAL OF DERMATOLOGY, Issue 5 2006
A.G. Messenger
Summary Background, The pathology of female pattern hair loss (FPHL) is characterized by an increase in the proportion of vellus follicles, manifest as a low terminal/vellus ratio. This is conventionally thought to be due to a progressive miniaturization of terminal hair follicles. There is also a prolongation of the latent period of the hair cycle (kenogen) in both male pattern hair loss and FPHL and follicles in kenogen may be difficult to classify histologically. Therefore, a low terminal/vellus ratio could be due to a preferential increase in the number of terminal follicles in kenogen rather than to a true increase in the number of vellus follicles. Objectives, To establish whether there is an increase in the absolute number of vellus follicles during the progression of FPHL, indicating a process of follicular miniaturization. Methods, We studied 42 women complaining of hair loss. The severity of the hair loss was graded clinically on a five-point scale from 1 (no obvious hair loss) to 5 (severe hair loss). Three 4-mm punch biopsies were taken from the frontal scalp of each patient, sectioned horizontally and stained with haematoxylin and eosin. Two levels were studied on each biopsy: through the mid-infundibular region and through the mid-isthmus. The following were counted: total follicles, terminal follicles, vellus follicles, anagen and telogen/catagen follicles. The results from the three biopsies from each subject were averaged and statistical evaluations performed on the mean values. Results, There was a progressive decline in mean total follicle count with increasing grade of hair loss (grade 1, 317 cm,2; grade 5, 243 cm,2) and a more pronounced reduction in terminal follicle counts (grade 1, 263 cm,2; grade 5, 96 cm,2). The absolute number of vellus follicles increased from 33 cm,2 (grade 1) to 71 cm,2 (grade 4), declining to 51 cm,2 at grade 5. The terminal/vellus ratio fell from 12·8 (grade 1) to 2·3 (grade 4) and remained at this level thereafter. The proportion of follicles in telogen increased from 13·7% (grade 1) to 31·4% (grade 5). Conclusions, Our results show that there is an increase in vellus follicle numbers with increasing severity of hair loss in women with FPHL, suggesting that terminal follicles do indeed miniaturize. It is possible that there is also an increase in the number of follicles in a latent stage of telogen but this was difficult to assess from our data. The fall in total follicle counts with stabilizing of the terminal/vellus ratio in severe hair loss suggests that miniaturization does not stop with a vellus follicle but progresses to follicular deletion. [source]

Topical tacrolimus suppresses the expression of vascular endothelial growth factor and insulin-like growth factor-1 in late anagen

CLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 8 2009
Y. Wang
Summary Tacrolimus has shown promising results in the treatment of various dermatological diseases, including hair loss. The direct effect of tacrolimus on hair follicles and its underlying mechanisms have rarely been investigated. In this study, we investigated the effects of topical tacrolimus on anagen in the hair cycle and on the expression of vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1) mRNAs in mouse skin. Topical tacrolimus 0.1% ointment was applied to one side of the skin of depilated C57BL/6 mice. Skin samples from both sides were taken during the study. Vegf and Igf-1 mRNA were determined by quantitative RT-PCR. No obvious difference in skin colour, hair cycling or histological features was found between the treated and untreated skin, but the levels of Vegf mRNA and Igf-1 mRNA were markedly decreased in the treated skin in late anagen, compared with those in untreated skin. [source]

Hedgehog signaling maintains hair follicle stem cell phenotype in young and aged human skin

AGING CELL, Issue 6 2009
Laure Rittié
Summary Skin hair follicles (HF) contain bulge stem cells (SC) that regenerate HFs during hair cycles, and repair skin epithelia following injury. As natural aging is associated with decreased skin repair capacity in humans, we have investigated the impact of age on human scalp HF bulge cell number and function. Here, we isolated human bulge cells, characterized as CD200+/KRT15+/KRT19+ cells of the HF, by dissection-combined CD200 selection in young and aged human skin. Targeted transcriptional profiling indicates that KRT15, KRT19, Dkk3, Dkk4, Tcf3, S100A4, Gas1, EGFR and CTGF/CCN2 are also preferentially expressed by human bulge cells, compared to differentiated HF keratinocytes (KC). Our results demonstrate that aging does not alter expression or localization of these HF SC markers. In addition, we could not detect significant differences in HF density or bulge cell number between young and aged human scalp skin. Interestingly, hedgehog (Hh) signaling is activated in human bulge cells in vivo, and down-regulated in differentiated HF KCs, both in young and aged skin. In addition, activation of Hh signaling by lentivirus-mediated overexpression of transcription factor Gli1 induces transcription of HF SC markers KRT15, KRT19, and Gas1, in cultured KCs. Together with previously reported knock-out mouse results, these data suggest a role for Hh signaling in maintaining bulge cell phenotype in young and aged human skin. [source]