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Current Biology : CB Feb 2009Hair is a primary characteristic of mammals, and exerts a wide range of functions including thermoregulation, physical protection, sensory activity, and social... (Review)
Review
Hair is a primary characteristic of mammals, and exerts a wide range of functions including thermoregulation, physical protection, sensory activity, and social interactions. The hair shaft consists of terminally differentiated keratinocytes that are produced by the hair follicle. Hair follicle development takes place during fetal skin development and relies on tightly regulated ectodermal-mesodermal interactions. After birth, mature and actively growing hair follicles eventually become anchored in the subcutis, and periodically regenerate by spontaneously undergoing repetitive cycles of growth (anagen), apoptosis-driven regression (catagen), and relative quiescence (telogen). Our molecular understanding of hair follicle biology relies heavily on mouse mutants with abnormalities in hair structure, growth, and/or pigmentation. These mice have allowed novel insights into important general molecular and cellular processes beyond skin and hair biology, ranging from organ induction, morphogenesis and regeneration, to pigment and stem cell biology, cell proliferation, migration and apoptosis. In this review, we present basic concepts of hair follicle biology and summarize important recent advances in the field.
Topics: Animals; Hair Diseases; Hair Follicle; Mice; Morphogenesis; Stem Cells
PubMed: 19211055
DOI: 10.1016/j.cub.2008.12.005 -
The Journal of Investigative... Dec 2007Shiny hair with a smooth texture and clean-cut ends or tapered tips is generally perceived to be healthy. Hair texture and shine relate to hair surface properties,... (Review)
Review
Shiny hair with a smooth texture and clean-cut ends or tapered tips is generally perceived to be healthy. Hair texture and shine relate to hair surface properties, whereas the integrity of hair ends relates to the hair cortex. Hair can be straight, wavy or curly, blonde, black, brown, red, gray white, and its natural variations are important to our identity. Manipulation of the normal structure of the hair shaft is epidemic and dictated by culture, fashion, and above all, celebrity. Although cosmetic procedures are intrinsically safe, there is potential for damage to the hair. Loss of lustre, frizz, split ends, and other hair problems are particularly prevalent among people who repeatedly alter the natural style of their hair or among people with hair that is intrinsically weak. This may be due to individual or racial variation or less commonly an inherited structural abnormality in hair fiber formation. Hair health is also affected by common afflictions of the scalp as well as age-related phenomena such as graying and androgenetic alopecia. Hair products that improve the structural integrity of hair fibers and increase tensile strength are available, as are products that increase hair volume, reduce frizz, improve hair manageability, and stimulate new hair growth.
Topics: Eicosanoic Acids; Female; Hair; Hair Diseases; Hair Preparations; Humans; Hygiene
PubMed: 18004288
DOI: 10.1038/sj.jidsymp.5650046 -
Actas Dermo-sifiliograficas Jan 2023Alopecia areata is an autoimmune disease that affects the hair follicle and can present as bald patches on the scalp and hair loss in other parts of the body. Diagnosis... (Review)
Review
Alopecia areata is an autoimmune disease that affects the hair follicle and can present as bald patches on the scalp and hair loss in other parts of the body. Diagnosis is clinical but can be aided by trichoscopy, a simple, rapid technique that reduces the need for invasive procedures and can also help with monitoring treatment response. We review the usefulness of trichoscopy in alopecia areata. The most common trichoscopic findings are yellow dots, black dots, exclamation mark hairs, short vellus hairs, and coudability hairs. Other, less common, findings can also help establish a diagnosis. Good response to treatment is indicated by the disappearance of black dots, broken hairs, and exclamation mark hairs. The observation of yellow dots, by contrast, indicates chronic disease and poor response to treatment.
Topics: Humans; Alopecia Areata; Dermoscopy; Hair; Alopecia; Hair Follicle; Hair Diseases
PubMed: 36067826
DOI: 10.1016/j.ad.2022.08.018 -
Indian Journal of Dermatology,... 2013The hair cosmetic industry has undergone a revolutionary change over the last two decades. The focus has dramatically veered from merely cleaning to repair, increasing... (Review)
Review
The hair cosmetic industry has undergone a revolutionary change over the last two decades. The focus has dramatically veered from merely cleaning to repair, increasing the tensile strength, reducing oxidative damage, and stimulating growth. Newer shorter procedures to make hair look naturally more lustrous, smooth, and manageable have evolved. Specialized grooming products have been formulated to cleanse, calm, and condition the hair, and are tailored for different hair-types, for example, dry, dry-damaged, oily, colored, and gray hair. Other products are formulated to alter the color or structure of the hair shaft, for example, hair dyes, perming/relaxing. Hair sprays and waxes/gels, can alter the 'lift' of the hair-shaft. Although dermatologists are experts in managing scalp and hair diseases, the esthetic applications of newer cosmetic therapies still remain elusive. This article attempts to fill the lacunae in our knowledge of hair cosmetics and esthetic procedures relevant in today's rapidly changing beauty-enhancing industry, with special emphasis on the Indian scenario for chemical and 'natural' hair products.
Topics: Hair Color; Hair Diseases; Hair Dyes; Hair Preparations; Herbal Medicine; Humans; India
PubMed: 23974582
DOI: 10.4103/0378-6323.116734 -
Journal of the American Academy of... May 2019Cytotoxic chemotherapies, molecularly targeted therapies, immunotherapies, radiotherapy, stem cell transplants, and endocrine therapies may lead to hair disorders,... (Review)
Review
Cytotoxic chemotherapies, molecularly targeted therapies, immunotherapies, radiotherapy, stem cell transplants, and endocrine therapies may lead to hair disorders, including alopecia, hirsutism, hypertrichosis, and pigmentary and textural hair changes. The mechanisms underlying these changes are varied and remain incompletely understood, hampering the development of preventive or therapeutic guidelines. The psychosocial impact of chemotherapy-induced alopecia has been well documented primarily in the oncology literature; however, the effect of other alterations, such as radiation-induced alopecia, hirsutism, and changes in hair color or texture on quality of life have not been described. This article reviews clinically significant therapy-related hair disorders in oncology patients, including the underlying pathophysiological mechanisms, severity grading scales, patient-reported quality of life questionnaires, management strategies, and future translational research opportunities.
Topics: Alopecia; Antineoplastic Agents; Cryotherapy; Hair Diseases; Humans; Immunotherapy; Molecular Targeted Therapy; Neoplasms; Pigmentation Disorders; Quality of Life; Radiotherapy; Severity of Illness Index
PubMed: 29660422
DOI: 10.1016/j.jaad.2018.03.055 -
Clinical and Experimental Dermatology Dec 2022Menopause, which usually occurs between the age of 45 and 55 years, is associated with falling oestrogen levels due to ovarian follicle depletion. The impact on the... (Review)
Review
Menopause, which usually occurs between the age of 45 and 55 years, is associated with falling oestrogen levels due to ovarian follicle depletion. The impact on the cardiovascular system and bone density are well documented; however, further research required to establish the impact on the skin and hair. In this first part of a four-part review, we examine the effect of menopause on the hair. We performed a literature review on dermatology and hair in menopause. Androgens and oestrogens are involved with regulation of the hair cycle, with a reduction in anagen hairs seen in postmenopausal women. Female pattern hair loss and frontal fibrosing alopecia have both been associated with the perimenopausal and postmenopausal states. It is clear that menopause and the change in hormone levels have an impact on the hair cycle and common hair conditions. However, further research is required, particularly to understand the therapeutic targets and role of hormonal therapy.
Topics: Female; Humans; Middle Aged; Alopecia; Hair Diseases; Hair; Menopause; Skin; Estrogens
PubMed: 35796569
DOI: 10.1111/ced.15327 -
Biomedicine & Pharmacotherapy =... May 2021Androgenic alopecia (AGA), also known as male pattern baldness, is one of the most common hair loss diseases worldwide. The main treatments of AGA include hair...
Androgenic alopecia (AGA), also known as male pattern baldness, is one of the most common hair loss diseases worldwide. The main treatments of AGA include hair transplant surgery, oral medicines, and LDL laser irradiation, although no treatment to date can fully cure this disease. Animal models play important roles in the exploration of potential mechanisms of disease development and in assessing novel treatments. The present study describes androgen receptor (AR) in C57BL/6 mouse hair follicles that can be activated by dihydrotestosterone (DHT) and translocate to the nucleus. This led to the design of a mouse model of androgen-induced AGA in vivo and in vitro. DHT was found to induce early hair regression, hair miniaturization, hair density loss, and changes in hair morphology in male C57BL/6 mice. These effects of DHT could be partly reversed by the AR antagonist bicalutamide. DHT had similar effects in an ex vivo model of hair loss. Evaluation of histology, organ culture, and protein expression could explain the mechanism by which DHT delayed hair regrowth.
Topics: Alopecia; Androgen Antagonists; Anilides; Animals; Dihydrotestosterone; Disease Models, Animal; Hair Follicle; Male; Mice; Mice, Inbred C57BL; Nitriles; Organ Culture Techniques; Receptors, Androgen; Signal Transduction; Tosyl Compounds
PubMed: 33517191
DOI: 10.1016/j.biopha.2021.111247 -
Lasers in Medical Science Sep 2018Benefit deriving from the use of light is known since ancient time, but, only in the last decades of twentieth century, we witnessed the rapid expansion of knowledge and... (Review)
Review
Benefit deriving from the use of light is known since ancient time, but, only in the last decades of twentieth century, we witnessed the rapid expansion of knowledge and techniques. Light-emitted diode (LED)-based devices represent the emerging and safest tool for the treatment of many conditions such as skin inflammatory conditions, aging, and disorders linked to hair growth. The present work reviews the current knowledge about LED-based therapeutic approaches in different skin and hair disorders. LED therapy represents the emerging and safest tool for the treatment of many conditions such as skin inflammatory conditions, aging, and disorders linked to hair growth. The use of LED in the treatment of such conditions has now entered common practice among dermatologists. Additional controlled studies are still needed to corroborate the efficacy of such kind of treatment.
Topics: Aging; Alopecia; Humans; Light; Photochemotherapy; Photosensitizing Agents; Skin Diseases
PubMed: 30006754
DOI: 10.1007/s10103-018-2584-8 -
International Journal of Molecular... Jan 2014Hair follicle morphogenesis depends on Wnt, Shh, Notch, BMP and other signaling pathways interplay between epithelial and mesenchymal cells. The Wnt pathway plays an... (Review)
Review
Hair follicle morphogenesis depends on Wnt, Shh, Notch, BMP and other signaling pathways interplay between epithelial and mesenchymal cells. The Wnt pathway plays an essential role during hair follicle induction, Shh is involved in morphogenesis and late stage differentiation, Notch signaling determines stem cell fate while BMP is involved in cellular differentiation. The Wnt pathway is considered to be the master regulator during hair follicle morphogenesis. Wnt signaling proceeds through EDA/EDAR/NF-κB signaling. NF-κB regulates the Wnt pathway and acts as a signal mediator by upregulating the expression of Shh ligand. Signal crosstalk between epithelial and mesenchymal cells takes place mainly through primary cilia. Primary cilia formation is initiated with epithelial laminin-511 interaction with dermal β-1 integrin, which also upregulates expression of downstream effectors of Shh pathway in dermal lineage. PDGF signal transduction essential for crosstalk is mediated through epithelial PDGF-A and PDGFRα expressed on the primary cilia. Dermal Shh and PDGF signaling up-regulates dermal noggin expression; noggin is a potent inhibitor of BMP signaling which helps in counteracting BMP mediated β-catenin inhibition. This interplay of signaling between the epithelial and dermal lineage helps in epithelial Shh signal amplification. The dermal Wnt pathway helps in upregulation of epithelial Notch expression. Dysregulation of these pathways leads to certain abnormalities and in some cases even tumor outgrowth.
Topics: Animals; Hair Diseases; Hair Follicle; Humans; Morphogenesis; Signal Transduction
PubMed: 24451143
DOI: 10.3390/ijms15011647 -
Journal of Veterinary Diagnostic... May 2021Hair follicle neoplasms occur in many different species, including humans. In domestic animals, they are most common in dogs. Most hair follicle tumors are benign, but... (Review)
Review
Hair follicle neoplasms occur in many different species, including humans. In domestic animals, they are most common in dogs. Most hair follicle tumors are benign, but malignant neoplasms can also occur. To diagnose hair follicle neoplasms, a thorough knowledge of follicular anatomy is important, given that follicular tumors are classified according to the differentiation pattern seen in the corresponding part of the normal hair follicle. This review focuses on the key diagnostic features of hair follicle tumors and follicular cysts in dogs and cats.
Topics: Animals; Cat Diseases; Cats; Cysts; Dog Diseases; Dogs; Hair Diseases; Hair Follicle; Skin Neoplasms
PubMed: 33666111
DOI: 10.1177/1040638721993565