Valerie A Randall

University of Bradford | UB · Centre for Skin Sciences

Male sex hormones-androgens-regulate male physique development. Without androgen signaling, genetic males appear female. During puberty, increasing androgens harness the hair follicle's unique regenerative ability to replace many tiny vellus hairs with larger, darker terminal hairs (e.g., beard). Follicle response is epigenetically varied: some rem...

Balding causes widespread psychological distress but is poorly controlled. The commonest treatment, minoxidil, was originally an antihypertensive drug that promoted unwanted hair. We hypothesized that another serendipitous discovery, increased eyelash growth side-effects of prostamide F(2α)-related eyedrops for glaucoma, may be relevant for scalp a...

The concept of regenerative medicine is relatively new, but animals are well known to remake their hair and feathers regularly by normal regenerative physiological processes. Here, we focus on 1) how extrafollicular environments can regulate hair and feather stem cell activities and 2) how different configurations of stem cells can shape organ form...

Hair growth plays important roles in human social and sexual communication. People throughout the world classify a person's state of health, sex, sexual maturity and age, often subconsciously, by assessing their scalp and body hair. Hair's importance is seen in many social customs in different cultures. Hair removal generally has a strong depersona...

Alopecia causes widespread psychological distress, but is relatively poorly controlled. The development of new treatments is hampered by the lack of suitable human hair follicle models. Although intermediate and vellus hair follicles are the main clinical targets for pharmacological therapy, terminal hair follicles are more frequently studied as sm...

Androgenetic alopecia is a common, progressive, patterned loss of visible scalp hair. It causes psychological distress and negative effects on the quality of life. Adult levels of circulating androgens and functional intracellular receptors are essential prerequisites for the balding processes. Metabolism of circulating androgens, such as testoster...

This chapter reviews the functions of hair, its structure and the processes occurring during the hair growth cycle, the changes which can occur with the seasons, and the importance of the main regulator of human hair growth, the androgens. Its main focus lies on human hair growth. Mammalian skin produces hair everywhere except for the glabrous skin...

Hair's importance in human communication means that abnormalities like excess hair in hirsutism or hair loss in alopecia cause psychological distress. Androgens are the main regulator of human hair follicles, changing small vellus follicles producing tiny, virtually invisible hairs into larger intermediate and terminal follicles making bigger, pigm...

Hair disorders cause psychological distress but are generally poorly controlled; more effective treatments are required. Despite the long-standing use of minoxidil for balding, its mechanism is unclear; suggestions include action on vasculature or follicle cells. Similar drugs also stimulate hair, implicating ATP-sensitive potassium (K(ATP)) channe...

Androgens stimulate many hair follicles to alter hair colour and size via the hair growth cycle; in androgenetic alopecia tiny, pale hairs gradually replace large, pigmented ones. Since stem cell factor (SCF) is important in embryonic melanocyte migration and maintaining adult rodent pigmentation, we investigated SCF/c-Kit signalling in human hair...

• Hair follicles can produce different types of hair (length, thickness, colour) at various times in an individual’s life due to the follicle’s capacity to regenerate a new hair during the hair cycle. This allows hairs to change to correlate with alterations in season or sexual development, etc. • The type of hair produced is under endocrine contro...

Hair's importance for insulation and camouflage or human communication means that hairs need to change with season, age or sexual development. Regular, regenerating hair follicle growth cycles produce new hairs which may differ in colour and/or size, e.g., beard development. Hormones of the pineal-hypothalamus-pituitary axis coordinate seasonal cha...

The following is a review of a satellite symposium held at the British Medical Laser Association Meeting, in November 2005. Prof. V.A. Randall gave a comprehensive overview of hormones and hair growth, followed by an in-depth discussion of hirsutism, the therapeutic options, treatment and trends, by Dr. S. Lanigan. Dr. I. Hamzavi concluded the symp...

Background: Androgenetic alopecia, or male pattern baldness, is a common, progressive disorder where large, terminal scalp hairs are gradually replaced by smaller hairs in precise patterns until only tiny vellus hairs remain. This balding can cause a marked reduction in the quality of life. Although these changes are driven by androgens, most mole...

The ability of K + channel openers to stimulate hair growth has led to the adoption of topical minoxidil for the treatment of hair loss, although it appears only to be effective in some patients [35,36]. By contrast, the ability of other K + channel openers to cause hypertrichosis can limit their clinical applications. Our understanding of how mino...

Although ATP-sensitive potassium (K(ATP)) channel openers, e.g., minoxidil and diazoxide, can induce hair growth, their mechanisms require clarification. Improved drugs are needed clinically. but the absence of a good bioassay hampers research. K(ATP) channels from various tissues contain subtypes of the regulatory sulfonylurea receptor, SUR, and p...

no Alopecia areata is an immunologically mediated disease characterized by extreme variability not only in the time of initial onset of hair loss but in the duration, extent and pattern of hair loss during any given episode of active loss. These variables, as well as the unpredictable nature of spontaneous regrowth and lack of a uniform response to...

Since the way in which the hair follicle functions is not well understood, many hair disorders are poorly controlled. A range of in vitro and in vivo models have therefore been developed to investigate the cell biological and biochemical mechanisms involved in the organization of this complex tissue. These range from cultures of a single cell type,...

Androgens regulate many aspects of human hair growth in both sexes. After puberty they transform tiny vellus follicles in many areas, e.g. the face, to terminal ones producing long, thick, pigmented hairs. In genetically predisposed individuals, androgens also cause the reverse transformation of terminal scalp follicles into vellus ones, causing ba...

Red deer stags produce an androgen-dependent mane of long hairs only in the breeding season; in the non-breeding season, when circulating androgen levels are low, the neck hair resembles the rest of the coat. This study was designed to determine whether androgen receptors are present in deer follicles throughout the year or only in the mane (neck)...

Androgens are the main regulator of normal human hair growth. After puberty, they promote transformation of vellus follicles, producing tiny, unpigmented hairs, to terminal ones, forming larger pigmented hairs, in many areas, e.g. the axilla. However, they have no apparent effect on the eyelashes, but can cause the opposite transformation on the sc...

Androgens stimulate many hair follicles, e.g., beard, but may cause regression on the scalp; occipital areas are considered androgen independent. The mesenchyme-derived dermal papilla that regulates the hair follicle is considered the site of androgen action. Because hair size has been clearly related to dermal papilla size, one of the key function...

Androgens can gradually transform large scalp hair follicles to smaller vellus ones, causing balding. The mechanisms involved are unclear, although androgens are believed to act on the epithelial hair follicle via the mesenchyme-derived dermal papilla. This study investigates whether the levels and type of androgen receptors in primary lines of cul...

Human hair growth plays a major role in social and sexual communication. Often subconsciously people all over the world classify a person’s state of health, sex, sexual maturity and age by assessing their scalp and body hair.

The mesenchyme-derived dermal papilla plays a major regulatory role in the complex cell biology of the hair follicle. The ability to culture dermal papilla cells from a range of species and particularly a range of normal and disordered human hair follicles has enabled the development of a powerful new model system for investigating hair follicle bi...

Alopecia areala is a form of balding whose aetiology is uncertain. Although the dermal papilla in the hair bulb regulates the iollicie and may play a part in the pathogenesis of alopecia areata. Its ultrastructure has not been well described. As clinically normal, i.e. non-balding, follicles from alopecia areata scalps show abnormalities at the lig...

Red deer stags annually grow two distinct seasonal coats, a winter coat and a summer coat; in addition, they produce a mane during the breeding season when plasma testosterone levels are high, which is replaced by the short neck hairs of the summer coat when testosterone levels are low. As two very different hair types are produced from the same fo...

As stem cell factor (SCF) and its receptor, c-kit, are involved in hair pigmentation, SCF is probably produced in the skin, possibly by the regulatory follicular dermal papilla. Since androgens often alter the type and color of hair, probably via the dermal papilla, they may regulate its SCF production. SCF produced by beard and non-balding scalp d...

Androgens regulate the growth of many human hair follicles, but only pubic, axillary, and scalp hair growth occur in men with 5α-reductase deficiency. This suggests that 5α-dihydrotestosterone is the active intracellular androgen in androgen-dependent follicles, except in the axilla and pubis. Since the dermal papilla plays a major regulatory role...

Male pattern baldness is a common, androgen-dependent skin problem in adult men which is not well understood, although androgens are believed to act on the hair follicle via the mesenchyme-derived dermal papilla situated in the middle of the hair follicle bulb. Since dermal papilla cells retain specific characteristics in culture, such as hair-grow...

The red deer is a seasonally breeding mammal with a circannual cycle of prolactin secretion which reaches its peak during the non-breeding season. This study investigated expression of the prolactin receptor gene in red deer tissues collected in the breeding and non-breeding seasons. A 562 bp fragment of the extracellular domain of the red deer pro...

The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.

Although the ultrastructure of the dermal-epidermal junction has been well characterized, little is known about the junctions between the dermal papilla and the surrounding epithelial cells of the hair bulb, or between the connective tissues and the epithelial cells on the outside of the hair follicle. Because the dermal papilla plays a major role...

The mechanism of androgen action varies in different tissues, but in the majority of androgen target tissues either testosterone or 5α-dihydrotestosterone (DHT) binds to a specific androgen receptor to form a complex that can regulate gene expression. Testosterone is metabolized to DHT by the enzyme 5α-reductase. The autosomal recessive genetic dis...

Androgens are major regulators of human hair growth with paradoxically different effects on hair follicles depending on their body site. They stimulate terminal growth in many regions including the face, have no effect on eyelashes, but may cause inhibition and balding on the scalp in genetically disposed individuals. How this occurs is unknown. Ho...

Objective: Androgens have paradoxically different effects on hair follicles depending on body site, stimulating beard growth while inducing regression in some areas of the scalp. The mesenchyme derived dermal papilla at the base of the hair follicle regulates many aspects of the growth of follicular epithelium, and is probably the site of androgen...

Many hair follicles produce different types of hair in response to environmental changes or the mammals age, that are translated to the follicle by hormones. Androgens cause many changes, such as transforming vellus follicles producing insignificant hairs on the face to terminal beard ones at puberty or the reverse on the scalp. In male red deer th...

Androgens are major regulators of human hair growth, but their effects vary: many follicles are stimulated by androgens, e.g., beard; some remain unaffected, e.g., eyelashes; whereas scalp follicles undergo regression and balding in genetically disposed individuals. Because the dermal papilla controls many aspects of the hair follicle, androgens ma...

Androgens stimulate hair growth in many areas, e.g. the beard; they also induce regression and balding on the scalp with increasing age in genetically disposed individuals. The cause(s) of this biological conundrum is unknown but age-related; androgen-potentiated changes also occur in the prostate. The mesenchymederived dermal papilla situated at t...

Androgens stimulate hair growth in some areas, e.g., beard, but may cause regression and baldness on the scalp. The mesenchyme-derived dermal papilla is believed to regulate many aspects of hair growth. It is probable that androgens exert their effect on hair growth via the dermal papilla. In this study the effect of androgens on the growth of cult...

The "active" edges of patches of alopecia areata and normal areas from the same scalp (i.e., bearing normal terminal hair) from seven patients with alopecia areata were investigated immunohistologically. Similar areas from a further eight patients were examined using light and electronmicroscopy. "Active" and "normal" areas of alopecia areata scalp...

Various parameters of hair growth were determined every 28 days for 18 months in 14 healthy Caucasian men aged 18-39 with indoor occupations in Sheffield, U.K. (latitude 53.4 degrees N). In the scalp the proportion of follicles in anagen reached a single peak of over 90% in March, and fell steadily to a trough in September. The number of shed hairs...

The expression of basement membrane molecules and interstitial collagens in human hair follicle mesenchyme was studied by immunohistochemical staining of tissue sections and of cells cultured from dermal papillae. Type I and type III collagens were found in the dermal sheath and in the dermal papilla throughout the hair cycle. Laminin and type IV c...

The effects of combined treatment with the antiandrogen, cyproterone acetate, and ethinyl oestradiol on four women with long-standing hidradenitis suppurativa have been investigated. The condition was controlled successfully in all patients with 100 mg/day cyproterone acetate using the reversed sequential regimen; lowering the antiandrogen to 50 mg...

Male rat liver contains components in both cytosol and nucleosol which bind the synthetic testosterone derivative, mibolerone, with a high affinity, low capacity and a high specificity for androgens. Gel filtration chromatography shows two binding components. A high molecular weight component (M.Wt 230,000) present in cytosol alone and a low molecu...

1. We have bred a strain of pigs with an inherited condition of hypocalcaemic rickets, transmitted by an autosomal-recessive mechanism. 2. Homozygous (affected) piglets grew at half the rate of their heterozygous (clinically normal) littermates, and developed profound hypocalcaemia with severe secondary hyperparathyroidism and hypophosphataemia by...

In the absence of photoexcitation and under conditions of low ionic strength, the native form of the androgen receptor in rat prostate sediments as a large, 9.2S complex with tritiated androgens, including [3H]methyltrienolone. On photoexcitation, the configuration of labelled receptor complexes changes to a form of lower sedimentation coefficient,...

Antiandrogens, such as cyproterone acetate, and oestrogens both inhibit sebaceous secretion in rats and have a potentiality for the treatment of hirsutism and acne in the human female. However, they act at different points. In castrated rats treated with testosterone, 3 micrograms/day oestradiol produced a greater decrease in sebum secretion than a...

The assumption that the metabolism of testosterone to 5α-dihydrotestosterone (5α-DHT) is required for androgen action in the skin was investigated by studying the uptake and metabolism of testosterone by skin and other tissues of the rat in vivo. The skin resembled the classical androgen target organs in the uptake and retention of radioactivity, b...

The uptake and metabolism of radioactively labelled testosterone was investigated in vivo at various time intervals in the skin, plasma and other tissues of adult rats castrated 24 h earlier. After the addition of marker steroids the components of the tissue extracts were separated by partition and development in several chromatographic systems; st...

Sebum production was measured on 2 symmetrically placed areas on the flanks of rats over alternating periods of 18 and 6 hr for 4 days, by absorbing the lipid on pads of cigarette paper held in place by a specially designed harness. Castrated rats receiving testosterone produced about twice as much sebum as untreated littermate controls. Once daily...

Testosterone, previously considered to be the major androgen, 1 now appears to require metabolism by its target cell before it can be used (King and Mainwaring, 1974; Mainwaring, 1976). The simplified theory of androgen action (Fig. 1) considers that testosterone is carried around the body in the blood — both as free testosterone and bound to the p...

The quantitative changes in body hair growth, and sebaceous secretion, as well as plasma sex hormone binding globulin, luteinizing hormone and follicle stimulating hormone, testosterone and androstenedione were measured in a hirsute woman aged 21 years under ‘reverse sequential’ treatment with cyproterone acetate and ethinyl oestradiol. The subject...

The relative responses to testosterone of the prostate, preputial, Harderian, and lachrymal glands, the seminal vesicles and the brown adipose tissue, have been compared in litter-mate, castrated and hypophysectomized-castrated rats, with or without treatment with bovine GH. The responses of both prostate and preputial glands, though not the semina...

Alpha-Melanocyte-stimulating hormone was shown to act synergistically with testosterone to stimulate the sebaceous, prostate and the seminal vesicles in hypophys-ectomized-castrated rats. The sebaceous glands differed from the other three organs in that alpha-MSH not only acted synergistically, but also had a significant effect which was independen...

Sebum production of rats was assessed by measuring the levels of fat extractable by diethyl ether from samples of hair clipped immediately after shampooing with sodium lauryl sulphate and 2 days later. By the use of matched litter mates in was unequivocally demonstrated that the response of the sebaceous glands to testosterone is virtually abolishe...