The changes in the hair cycle during gestation and the post-partum period

Effects of Seasonality and Pregnancy on Hair Loss and Regrowth in Rhesus Macaques

Several studies have examined the etiology of alopecia, or hair loss, in rhesus macaques. While outcomes differ across studies, some commonalities have emerged. Females, particularly pregnant females, show more alopecia than males, and alopecia follows a seasonal pattern. Much research has explored causes of hair loss; however, alopecia can result from lack of hair growth in addition to hair loss. To better understand how sex, reproductive state, and season affect alopecia, we followed 241 rhesus macaques (Macaca mulatta) in outdoor breeding groups over one year, recording both alopecia severity and presence of hair regrowth. We found that both alopecia and hair regrowth followed a seasonal pattern; alopecia was highest in spring and lowest in late summer, while regrowth started in spring and peaked in late summer. Reproductive state also correlated with both alopecia and hair growth. Females in their third trimester had the highest average level of alopecia and the lowest amount of hair regrowth. Regrowth resumed postpartum, regardless of whether females were rearing an infant. Results indicate that the seasonal pattern of alopecia is due in part to the seasonal limitations on hair regrowth, and that breeding, which also occurs seasonally in rhesus macaques, may further suppress hair regrowth.

Clinical and phototrichogrammatic evaluation of estradiol replacement therapy on hair growth in postmenopausal Japanese women with female pattern hair loss: a pilot study

Background

Female pattern hair loss (FPHL) is known to present with characteristic pathological conditions, including reduced overall hair density. Female hormones affect hair condition; however, the detailed mechanism is unknown. Furthermore, research on the topic is complicated by the fact that senescent alopecia often occurs concurrently with FPHL. Therefore, we investigated the effect of estradiol, a female hormone, on hair growth by eliminating aging factors and objectively evaluating hair changes caused by female hormone replacement therapy (HRT).

Objective

This study was conducted to elucidate the mechanism through which female hormones exert their effects on hair.

Methods

The study included 11 female patients undergoing HRT who were evaluated before initiating HRT, 3 months after initiating HRT, and 6 months after initiating HRT. The thinning hair score, hair density, telogen hair rate, telogen plucking strength, hair growth rate, and hair thickness were measured and evaluated. Furthermore, hematological tests were performed to assess the general physical condition of the participants.

Results

HRT increased the telogen hair rate (P = .010, paired t test) at 3 months, improved frontal hairline thinning score (P = .008, Wilcoxon test), and increased the plucking strength (P = .013, paired t test) at 6 months.

Limitations

The limitation of this study included the relatively small sample size, inability to conduct further long-term tests because of participant burden, and lack of a control group.

Conclusion

The results suggested that HRT improved the appearance of the frontal hairline. As few studies have analyzed the effects of female hormones on human hair, a novel finding of this study was the effects of estradiol on the plucking strength after excluding age as a factor. We believe that these findings will contribute to understanding FPHL and developing female hormone-related treatments.

Effects of oxytocin on the hair growth ability of dermal papilla cells

Oxytocin (OXT) is a neuropeptide hormone termed "love hormone" produced and released during childbirth and lactation. It is also produced in response to skin stimulation (e.g., during hugging and massaging) and music therapy. The effects of OXT on various organs have been revealed in recent years; however, the relationship between hair follicles and OXT remains unclear. In this study, we examined the effects of OXT on dermal papilla (DP) cells that control hair growth by secreting growth/regression signals. Gene expression analysis revealed that DP signature markers were significantly upregulated in DP cells treated with OXT. In addition, we tested the hair growth-promoting effects of OXT using in vitro hair follicle organoids. OXT promoted the growth of hair peg-like sprouting by upregulating the expression of growth-promoting factors, including genes encoding vascular endothelial growth factor A (VEGFA). This study highlights the positive effects of OXT in hair follicles and may assist in the development of new treatments for alopecia.

Investigation of exacerbating factors for postpartum hair loss: a questionnaire-based cross-sectional study

Background

Although postpartum hair loss is believed to be common, there is little reliable information.

Objective

We sought to examine the factors that were associated with postpartum hair loss and to elucidate factors correlated with its pathogenesis.

Methods

We carried out a questionnaire-based cross-sectional study. The study participants were women who delivered at 2 facilities and filled the questionnaire 10-18 months after delivery. The survey questionnaire included baseline characteristics, pregnancy details, delivery, childcare, and extent of postpartum hair loss. We divided participants into 2 groups according to the absence or presence of postpartum hair loss and performed logistic regression analyses.

Results

A total of 331 (21.0%) responses were analyzed; among these 304 (91.8%) women had postpartum hair loss. The average time for the start, peak, and end of hair loss was 2.9, 5.1, and 8.1 months, respectively. Women with hair loss had an earlier time of delivery, a lower birth weight, a higher preterm labor rate, and longer-term breastfeeding. Logistical regression analyses revealed that longer-term breastfeeding and preterm labor were independent predictors of postpartum hair loss. The adjusted odds ratio for postpartum hair loss in women who ended breastfeeding 6-12 months postpartum versus those who ended it after 12 months or more was 5.96 (95% confidence interval [CI] [1.68, 21.09]) and 6.37 (95% CI [1.95, 20.76]) compared with those who stopped breastfeeding within 6 months postpartum.

Limitations

Finer details such as pregnancy complications and delivery information may not be accurate since all results are based on questionnaire responses. There may be a sampling bias because women who suffer from postpartum hair loss may tend to participate more frequently.

Conclusion

Over 90% of women experienced postpartum hair loss. Our data show that long-term breastfeeding and preterm labor correlate with postpartum hair loss.

Considerations for cutaneous physiologic changes of pregnancy that fail to resolve postpartum

Pregnancy prompts many adaptive and unique physiologic modifications, with cutaneous changes being possibly the most noticeable. These cutaneous changes are of interest to physicians, since they must be diagnosed as anticipated normal physiologic changes or potentially harmful and managed accordingly. Research has been conducted on physiologically normal and abnormal cutaneous manifestations of pregnancy but is lacking in regard to the persistence of these changes after delivery. This prompts the question as to whether these are normal physiologic changes taking longer to resolve, abnormal changes that may have been previously misdiagnosed, or a separate underlying change that is incorrectly attributed to a common dermatosis caused by pregnancy. Some of the conditions that may persist longer than expected during or after pregnancy, and thus require further workup for an underlying condition, include telogen effluvium, severe hirsutism, palmar erythema, and striae. The objective of this review is to focus on these four common cutaneous physiologic changes of pregnancy, and what to consider when they do not resolve as expected.

Maternal hair cortisol concentrations across pregnancy and the early postpartum period in a Puerto Rican sample

OBJECTIVE

Hair cortisol is a noninvasive, long-term biomarker of human stress. Strengths and weaknesses of this biomarker as a proxy measure of perinatal stress are not yet well understood. Hair cortisol data were collected from pregnant women in Puerto Rico to investigate maternal cortisol level variance across pregnancy.

METHODS

In 2017, we recruited 86 pregnant women planning to birth at a large urban hospital. We aimed to collect four hair samples from each participant, one in each trimester and one in the postpartum period.

RESULTS

Median cortisol in the first trimester (n = 82) was 5.7 picograms/milligram (pg/mg) (range: 1.0-62.4). In the second, third, and postpartum periods, the medians were 6.8 pg/mg (1.0-69.5), (n = 46), 20.1 pg/mg (5.6-89.0), (n = 30), and 14.1 pg/mg (1.7-39.8), (n = 9), respectively. These medians disguise a 10-fold and 50-fold variability for two participants. Our sample sizes declined sharply when Hurricane Maria caused major disruptions in services and participants' lives.

CONCLUSION

Maternal hair cortisol concentrations were lower in the first and second trimester than the third trimester and early postpartum period. We also observed a wide range of variation in cortisol levels throughout pregnancy and in the postpartum period.

Trichoscopic features of hair and scalp in noncomplaining individuals: A descriptive study

BACKGROUND

Trichoscopy is a simple noninvasive tool that is used in calculating different hair parameters and the diagnosis of different hair/scalp diseases at variable magnifications.

OBJECTIVE

The aim of this work is to describe the features and parameters of hair and scalp in a healthy sample of Egyptian population using videodermoscopy. This may help to provide standard range of measurements of normal hair in both males and females.

METHODS

A nonrandomized, observational study for features and parameters of hair structure, performed on 368 healthy Egyptian subjects with no hair/scalp complaint.

RESULTS

Each scalp area has its own vascular pattern. Male subjects showed different values regarding their hair parameters from the female subjects. No significant difference was seen after application of hair dye, except for few values. In both genders, there was a change in hair parameters with age. Smoking had a negative influence on hair parameters.

CONCLUSION

Hair features and parameters observed in our population are different from those reported by other populations. Smoking affects hair thickness and density. Dyed hair has greater thickness mostly due to the protective effect of hair conditioners.

Stress-associated ectopic differentiation of melanocyte stem cells and ORS amelanotic melanocytes in an ex vivo human hair follicle model

Hair greying depends on the altered presence and functionality of hair follicle melanocytes. Melanocyte stem cells (MelSCs) reside in the bulge of hair follicles and give rise to migrating and differentiating progeny during the anagen phase. Ageing, genotoxic stress, redox stress and multiple behaviour-associated acute stressors have been seen to induce hair greying by depleting the MelSC pool, a phenomenon which is accompanied by ectopic pigmentation of these cells, followed by their depletion from the stem cell niche. This aberrant differentiation produces a state from which a return to stem cell-like quiescence appears to be lost. The cellular features of stress-induced hair greying have been extensively studied in murine models. Here, we describe a method to assess and quantify human hair follicle MelSC differentiation by measuring ectopically pigmented MelSCs in isolated human hair follicles exposed to specific stress signal mediators. Ionizing radiation, hydrogen peroxide and noradrenaline have been shown to cause hair greying in mice. We demonstrate here that isolated, ex vivo cultured human hair follicles exposed to these treatments display similar ectopic pigmentation within the bulge area which is accompanied by induction of differentiated melanocytic markers. This study suggests that as in murine models, stress signalling induces closely matching phenotypic changes in human hair follicles which can be monitored and studied as a surrogate model for early steps in human hair greying.

Investigation of grape sap on wingless/integrated and β-catenin genes expression with histological factors on the hair follicle in rat

Background and purpose

Natural products are used to improve the damage caused by harmful reagents in various pathological situations. This study investigated the effect of grape sap as a natural product with antioxidant properties on follicle cell proliferation in bleomycin (as a chemotherapy agent with toxic effects on hair growth) treated rats skin.

Experimental approach

The bleomycin treated rats were administrated grape sap. Wingless/integrated (wnt) and β-catenin gene expression as follicle proliferative markers were evaluated using real-time polymerase chain reaction. Furthermore, histological factors and total antioxidant capacity were evaluated.

Findings / Results

The data showed that, grape sap increased the number of anagenic hair follicle in grape sap (100 mg/kg) group (P < 0.001), sebaceous glands (P < 0.001), blood vessel density (P < 0.001), and hair growth length (P < 0.001). Also, wnt and β-catenin gene expression was elevated. The data showed that wnt and β-catenin gene expression were elevated in grape sap treated animals versus bleomycin group (P < 0.01 and 0.001, respectively).

Conclusion and implications

Our finding showed that grape sap can be effective in increasing hair growth a gains bleomycin toxic effects on skin hair growth.

Telogen effluvium: a comprehensive review

Excessive hair shedding is a common and alarming phenomenon, usually complained about by women. The disorder, named telogen effluvium (TE), bears several problems which are discussed in this essay. They are as follows: 1) how profuse a hair loss must be for TE to be diagnosed; 2) its heterogeneity that needs to be properly classified; 3) its distinction from androgenetic alopecia (AGA) with which it is often associated; 4) its main symptom, trichodynia, which is unclear how frequent and how diagnostic could be; 5) why histopathology has been reported to be nonspecific; and 6) its management, from diagnosis to treatment. A common mistake of the dermatologist is to minimize the complaint. Instead, the disorder may have a profound impact on the patients' mind and would require attention, time, and empathy.

Effects of Pregnancy, Outdoor Access, and Antifungal Medication on Hair Loss in Breeding-age Female Pigtailed Macaques (Macaca nemestrina)

Over 18 mo, adult female pigtailed macaques (Macaca nemestrina) housed at a breeding facility in Arizona were monitored every 6 mo for alopecia. The study period coincided with the movement of a majority of animals from primarily outdoor housing to continuous indoor housing and a corresponding decrease in available space. These changes were made due to the newly recognized prevalence of coccidioidomycosis at this site. The effects of pregnancy status, changes in outdoor access or space, and administration of fluconazole for the treatment of coccidioidomycosis on alopecia were explored. In this group of pigtailed macaques pregnancy did not appear to affect alopecia, in contrast to findings from a closely related species, rhesus macaques. Fluconazole administration increased alopecia in older animals but not in the youngest age group. Conversely, the effects of limited outdoor access or decreased space on increasing alopecia were greatest in the youngest group of animals.

Pattern of skin diseases in a university hospital in Jeddah, Saudi Arabia: age and sex distribution

BACKGROUND

Previous studies have investigated the pattern of dermatological diseases in some regions of Saudi Arabia, but studies on the prevalence of skin diseases in Jeddah are lacking.

OBJECTIVES

Assess the pattern of skin diseases in Jeddah based on age and sex differences and compare the results with those of previous studies conducted in other regions of Saudi Arabia and the Middle East.

DESIGN

A cross-sectional prevalence study, retrospective.

SETTING

Dermatology clinic of King Abdulaziz University hospital.

PATIENTS AND METHODS

Data obtained from electronic medical records were summarized and analyzed. We only included new patients, who first visited the clinic in 2017.

MAIN OUTCOME MEASURES

Descriptive epidemiological data and statistical comparisons.

SAMPLE SIZE

1244.

RESULTS

Among 3458 patients who attended the dermatology clinic, 1244 were new patients. There were 365 (29.3%) men and 879 (70.7%) women for a male-to-female ratio of 1:2.4. The mean (SD) age of the total population was 35 (3.8) years. The most common dermatological disease was dermatitis (n=266, 21.4%), followed by acne (n=195, 15.7%) and fungal infection (n=136, 10.9%). Atopic dermatitis was the most prevalent dermatome in children (41.7%), while acne was the most prevalent disease in adults (19.5%). The chi-square test indicated a significant difference between acne and sex (P=.007), with adult women being more commonly affected (79%) and for alopecia and sex (P less than .001), with women being more commonly affected (91.2%).

CONCLUSIONS

There are slight differences in the prevalence of dermatological diseases in Jeddah, as shown in this study and other studies from other regions in Saudi Arabia and the Middle East. We recommend initiating awareness campaigns to increase knowledge about skin diseases, particularly in men, and improving dermatology-related training programs for primary health care physicians. A population-based study is warranted to clarify the prevalence of skin diseases in Saudi Arabia.

LIMITATIONS

The inclusion of patients who visited the dermatology clinic only in 2017 and data collection from only registration records.

CONFLICT OF INTEREST

None.

Metabolomics of Pregnancy Complications: Emerging Application of Maternal Hair

In recent years, the study of metabolomics has begun to receive increasing international attention, especially as it pertains to medical research. This is due in part to the potential for discovery of new biomarkers in the metabolome and to a new understanding of the "exposome", which refers to the endogenous and exogenous compounds that reflect external exposures. Consequently, metabolomics research into pregnancy-related issues has increased. Biomarkers discovered through metabolomics may shed some light on the etiology of certain pregnancy-related complications and their adverse effects on future maternal health and infant development and improve current clinical management. The discoveries and methods used in these studies will be compiled and summarized within the following paper. A further focus of this paper is the use of hair as a biological sample, which is gaining increasing attention across diverse fields due to its noninvasive sampling method and the metabolome stability. Its significance in exposome studies will be considered in this review, as well as the potential to associate exposures with adverse pregnancy outcomes. Currently, hair has been used in only two metabolomics studies relating to fetal growth restriction (FGR) and gestational diabetes mellitus (GDM).

Short communication: Temporal changes in the skin morphology of dairy cows during the periparturient period

Management of dairy cow productivity requires monitoring of their nutritional status by visual observation. It has been suggested that changes in hair coat appearance are among the indicators of nutritional state in dairy cows. Temporal changes in the skin morphology in cows, however, have not been reported. In this study, we examined the changes in the skin of dairy cows that occur during the peripartum period. Seven pluriparous cows were used. Skin samples were collected at 28 d before the due date and 28 d and 56 d after calving for morphological examination. Hair follicle width was 108.8 ± 5.9 µm (±SD) in the dry period, 95.5 ± 5.5 µm at 28 d after calving, and 104.2 ± 5.3 µm at 56 d postpartum. The percentages of anagen hair follicles during these 3 periods were 41.4 ± 3.4, 18.5 ± 3.4, and 32.3 ± 3.3%, respectively. The corresponding sebaceous gland sizes were 8,362.0 ± 707.6, 7,800.0 ± 831.4, and 9,186.8 ± 962.6 µm², respectively. Hair follicle width was positively correlated with percentage of anagen hair follicles. The thickness of epidermal and proliferation rate of epidermal cell were also correlated. However, the hair follicle width, sebaceous gland size and cell proliferation rate, and thickness and proliferation rate of epidermal cells did not show any marked changes.

Analysis of sequential hair segments reflects changes in the metabolome across the trimesters of pregnancy

The hair metabolome has been recognized as a valuable source of information in pregnancy research, as it provides stable metabolite information that could assist with studying biomarkers or metabolic mechanisms of pregnancy and its complications. We tested the hypothesis that hair segments could be used to reflect a metabolite profile containing information from both endogenous and exogenous compounds accumulated during the nine months of pregnancy. Segments of hair samples corresponding to the trimesters were collected from 175 pregnant women in New Zealand. The hair samples were analysed using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. In healthy pregnancies, 56 hair metabolites were significantly different between the first and second trimesters, while 62 metabolites were different between the first and third trimesters (p < 0.05). Additionally, three metabolites in the second trimester hair samples were significantly different between healthy controls and women who delivered small-for-gestational-age infants (p < 0.05), and ten metabolites in third trimester hair were significantly different between healthy controls and women with gestational diabetes mellitus (p < 0.01). The findings from this pilot study provide improved insight into the changes of the hair metabolome during pregnancy, as well as highlight the potential of the maternal hair metabolome to differentiate pregnancy complications from healthy pregnancies.

Physiologic changes of pregnancy: A review of the literature

Throughout pregnancy, the body undergoes a variety of physiologic changes. The cutaneous findings can be most noticeable and often worrisome to both physicians and patients. Obstetricians and dermatologists must be able to differentiate between changes that are benign and those that may be pathologic. Most physicians recognize benign changes that are commonly described in literature such as hyperpigmentation, melasma, striae gravidarum, and telogen effluvium; however, they may be unaware of changes that tend to be less frequently discussed. This comprehensive review provides a broad overview of the physiologic cutaneous changes that occur during pregnancy as described in the literature over the past 10 years.

Hair chemical element contents and influence factors of reproductive-age women in the West Ujimqin Banner, Inner Mongolia, China

Women have an increased risk for chemical element deficiencies during reproductive age, particularly due to higher chemical element requirements and poor diets. Twenty-one chemical elements (Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Se, Si, Sn, Sr, Ti, V and Zn) in hair samples, which were collected from 71 non-pregnant and 236 pregnant women living in the West Ujimqin Banner, central Inner Mongolia, China, were measured, and the environment, dietary habits and ethnic group influence factors associated with the biomarker were analyzed. The results indicated that the average values of the chemical element contents from hair were greatly different compared to those from other areas, especially the Al, Cd, Pb, Ca and Sr contents. There was no significant difference among the three ethnicities for any element except Mn and Ti in non-pregnant women. Compared to non-pregnant women, in the first trimester group, the levels of nine chemical elements (Ba, Cd, Cu, Pb, Se, Si, Sn and Ti) decreased, while the others increased, and the contents of all of the chemical elements decreased in the second trimester group, while in the third trimester, there was a slight increase. Three chemical elements (Cu, Mn and Zn) displayed a synergistic correlation between each other in the third trimester group, which may protect the placenta from some oxidant damage. The high levels of Cd and Pb in hair likely originate from house renovations and traffic pollution. This study provided basic and useful information on the levels of chemical elements in reproductive-age women, and the results of this study are helpful to control the contents and improve the health of pregnant and non-pregnant women.

Presence of Mast Cells and Mast Cell Degranulation in Scalp Biopsies of Telogen Effluvium

BACKGROUND

Telogen effluvium (TE) is a type of acquired, diffuse alopecia that occurs due to an abnormal shift of scalp hair follicles from anagen to telogen, leading to premature shedding of hair. Previous studies have suggested the existence of a neuroimmunologic "brain-hair follicle" axis, in which mast cells have been implicated as an important link between the nervous system and immunologic system.

OBJECTIVE

The current study sought to investigate the role of mast cell presence and mast cell degranulation in the pathogenesis of TE.

MATERIALS AND METHODS

Mast cells were counted using Giemsa and tryptase immunohistochemical stains in scalp biopsy specimens with the pathologic diagnosis of TE (TE, n = 10), alopecia areata (AA, n = 7), and androgenic alopecia (ANDRO, n = 9).

RESULTS

We found significant (P < 0.001) group-level differences between the mean mast cell counts per high-power fields for each type of alopecia studied. Tukey post hoc analysis showed the mean mast cell count for TE to be significantly larger than AA for both Giemsa (P = 0.002) and tryptase (P = 0.006); significantly larger than ANDRO for both Giemsa (P < 0.001) and tryptase (P < 0.001); and significantly larger when compared to normal scalp skin for both Giemsa (P < 0.001) and tryptase (P < 0.001). No significant difference of mean mast cell counts was observed for AA compared to ANDRO for Giemsa (P = 0.373) or tryptase (P = 0.598) stains.

CONCLUSION

Our findings suggest that mast cells could play a role in mediating stress-induced hair loss seen in TE.

Pregnancy and the hair growth cycle: anagen induction against hair growth disruption using Nourkrin® with Marilex® , a proteoglycan replacement therapy

Postpartum effluvium is a well-known clinical fact. However, following some minor research activities in the 1960s, very little has happened on the research front of the subject. It was hypothesized that postpartum hair loss might be a manifestation of a change in the hair growth cycle occurring normally during pregnancy. Recently, new research has been published trying to explain the mechanism of action behind this frequently occurring hair growth disruption, and to develop a functional treatment schedule and regime. Under normal circumstances, postpartum effluvium will disappear by itself as a function of time, and therefore adequate information to the patient is important in order to reduce the anxiety that it will not be a permanent problem. However, in some subjects it can manifest itself for longer stages and even become permanent. At the present time, treatments aim at correcting underlying hormonal imbalances and at improving overall cosmetic appearance. Several treatments in the form of thyroid supplementation, topical progesterone and estradiol lotions, and even oral contraceptive have been studied. All the available studies have significant limitations in their scientific basis, such as small sample size, absence of control group, or highly subjective measurement of treatment response. It is evident from the available studies that no specific treatment has been investigated thoroughly enough to justify recommendation in clinical treatment or to be termed "effective." Without the ability to provide a pathogenic diagnosis or causality criteria, chances are low that a treatment by trial and error will adequately be able to control hair effluvium. Current hair treatment strategies are symptomatic and nonspecific; therefore, future research must aim at developing new and targeted methods with a point of departure in observing concomitant biological mechanisms. Based on the research in the 1960s, current knowledge about the hair follicle and the regulation of the hair cycles, we believe that an anagen inducer in the form of a specific proteoglycan replacement therapy (Nourkrin^® with Marilex^® from Pharma Medico) could be a proper solution to shorten the hair eclipse phenomenon - and give the patient a feeling of control and empowerment.

The Postpartum Telogen Effluvium Fallacy

INTRODUCTION

Postpartum telogen effluvium (PPTE) is a commonly described entity, but few studies deal with the real incidence and pathogenesis of this claimed common disease.

OBJECTIVE

To analyze the objective data published and to define the real incidence of the so-called PPTE.

METHOD

A retrospective review of the published data was conducted.

RESULTS

No statistically significant data were found in any of the papers reviewed, which could support the conclusion that the amount of hair shedding between pregnant and postpartum women is different.

CONCLUSION

PPTE is not a well-defined entity, and the exact incidence is unknown. From our literature review, we could state that the frequency of PPTE is so low and undefined that we dare say that PPTE does not exist.

The Hair Follicle: A Comparative Review of Canine Hair Follicle Anatomy and Physiology

The hair follicle (HF) has a wide range of functions including thermoregulation, physical and immunological protection against external insults, sensory perception, social interactions, and camouflage. One of the most characteristic features of HFs is that they self-renew during hair cycle (HC) throughout the entire life of an individual to continuously produce new hair. HC disturbances are common in humans and comparable to some alopecic disorders in dogs. A normal HC is maintained by follicular stem cells (SCs), which are predominately found in an area known as the bulge. Due to similar morphological characteristics of the human and canine bulge area, the particularity of compound HFs in humans and dogs as well as similarities in follicular biomarker expression, the dog might be a promising model to study human HC and SC disorders. In this review, we give an overview of normal follicular anatomy, the HC, and follicular SCs and discuss the possible pathogenetic mechanisms of noninflammatory alopecia.

Hair loss in women

Hair loss is a common cause of morbidity for many women. As a key member of the woman's health care team, the obstetrician/gynecologist may be the first person to evaluate the complaint of hair loss. Common types of nonscarring hair loss, including female pattern hair loss and telogen effluvium, may be diagnosed and managed by the obstetrician/gynecologist. A systematic approach to diagnosis and management of these common forms of hair loss is presented.

Calcineurin/Nfatc1 signaling links skin stem cell quiescence to hormonal signaling during pregnancy and lactation

In most tissues, the prevailing view is that stem cell (SC) niches are generated by signals from within the nearby tissue environment. Here, we define genetic changes altered in hair follicle (HF) SCs in mice treated with a potent SC activator, cyclosporine A (CSA), which inhibits the phosphatase calcineurin (CN) and the activity of the transcription factor nuclear factor of activated T cells c1 (Nfatc1). We show that CN/Nfatc1 regulates expression of prolactin receptor (Prlr) and that canonical activation of Prlr and its downstream signaling via Jak/Stat5 drives quiescence of HF SCs during pregnancy and lactation, when serum prolactin (Prl) levels are highly elevated. Using Prl injections and genetic/pharmacological loss-of-function experiments in mice, we show that Prl signaling stalls follicular SC activation through its activity in the skin epithelium. Our findings define a unique CN-Nfatc1-Prlr-Stat5 molecular circuitry that promotes persistent SC quiescence in the skin.

Blood and hair manganese concentrations in pregnant women from the infants' environmental health study (ISA) in Costa Rica

Manganese (Mn), an essential nutrient, is a neurotoxicant at high concentrations. We measured Mn concentrations in repeated blood and hair samples collected from 449 pregnant women living near banana plantations with extensive aerial spraying of Mn-containing fungicide mancozeb in Costa Rica, and examined environmental and lifestyle factors associated with these biomarkers. Mean blood Mn and geometric mean hair Mn concentrations were 24.4 μg/L (8.9-56.3) and 1.8 μg/g (0.05-53.3), respectively. Blood Mn concentrations were positively associated with gestational age at sampling (β = 0.2; 95% CI: 0.1 to 0.2), number of household members (β = 0.4; 95% CI: 0.1 to 0.6), and living in a house made of permeable and difficult-to-clean materials (β = 2.6; 95% CI: 1.3 to 4.0); and inversely related to smoking (β = -3.1; 95% CI: -5.8 to -0.3). Hair Mn concentrations were inversely associated with gestational age at sampling (% change = 0.8; 95% CI: -1.6 to 0.0); and positively associated with living within 50 m of a plantation (% change = 42.1; 95% CI: 14.2 to 76.9) and Mn concentrations in drinking water (% change = 17.5; 95% CI: 12.2 to 22.8). Our findings suggest that pregnant women living near banana plantations aerially sprayed with mancozeb may be environmentally exposed to Mn.

Transgenic flash mice for in vivo quantitative monitoring of canonical Wnt signaling to track hair follicle cycle dynamics

Hair follicles (HFs) upon development enter a lifelong cycle of growth, regression, and resting. These phases have been extensively studied at the cellular and molecular levels for individual HFs. However, HFs group into domains with coordinated cycling strongly influenced by their environment. These macroscopic hair domains have been difficult to study and can be influenced by physiological or pathological conditions, such as pregnancy or skin wounds. To robustly address this issue, we generated a mouse model for quantitative monitoring of β-catenin activity reflecting HF cycle dynamics macroscopically by using live bioluminescence imaging. These mice allowed live tracking of HF cycles and development, and highlighted hair regenerative patterns known to occur through macro-environmental cues, including initiation events, propagating anagen and border stability, and allowed refinement of a mechanistic mathematical model that integrates epidermal cell population dynamics into an excitable reaction-diffusion model. HF cycling could be studied in situations of pregnancy, wound healing, hair plucking, as well as in response to cyclosporine or Wnt3a stimulation. In conclusion, we developed a model for analysis of HF cycling at the macroscopic level that will allow refined analysis of hair cycle kinetics as well as its propagation dynamics.