Genomic loci involved in sensing environmental cues and metabolism affect seasonal coat shedding in Bos taurus and Bos indicus cattle

Seasonal shedding of winter hair at the start of summer is well studied in wild and domesticated populations. However, the genetic influences on this trait and their interactions are poorly understood. We use data from 13,364 cattle with 36,899 repeated phenotypes to investigate the relationship between hair shedding and environmental variables, single nucleotide polymorphisms, and their interactions to understand quantitative differences in seasonal shedding. Using deregressed estimated breeding values from a repeated records model in a genome-wide association analysis (GWAA) and meta-analysis of year-specific GWAA gave remarkably similar results. These GWAA identified hundreds of variants associated with seasonal hair shedding. There were especially strong associations between chromosomes 5 and 23. Genotype-by-environment interaction GWAA identified 1,040 day length-by-genotype interaction associations and 17 apparent temperature-by-genotype interaction associations with hair shedding, highlighting the importance of day length on hair shedding. Accurate genomic predictions of hair shedding were created for the entire dataset, Angus, Hereford, Brangus, and multibreed datasets. Loci related to metabolism and light-sensing have a large influence on seasonal hair shedding. This is one of the largest genetic analyses of a phenological trait and provides insight into both agriculture production and basic science.

Hair Shedding Evaluation for Alopecia: A Refined Wash Test

PURPOSE

The aim of this study is to establish a refined wash test (RWT) and explore the characteristics of daily shedding hair parameters in normal individuals and patients with androgenetic alopecia (AGA) or telogen effluvium (TE).

MATERIALS AND METHODS

Chinese subjects diagnosed as normal, AGA or TE were enrolled. For the RWT procedure, the subjects were asked to pre-wash their hair 24 hours before the first collection, then to wash and rinse their hair with flowing water above a sink covered with a piece of filtering cloth. All hairs entrapped in the filtering cloth were air dried and collected. This "wash-and-collect" process was repeated for 3 consecutive days with a 24 ± 2 hour interval. Collected hairs were counted manually, and hair diameter was measured by videodermoscope. Number and diameter of daily shedding hairs and percentage of vellus and terminal hairs were analyzed.

RESULTS

A total of 176 subjects participated in and completed the study. Shedding hair number during daily shampooing was 27.9 ± 12.2, 52.2 ± 28.5 and 125.5 ± 62.7 hairs in normal, AGA and TE participants, respectively, and the differences between each two of the three groups were all statistically significant. Diameter of shedding hairs was 76.9 ± 9.0 μm, 60.0 ± 9.5 μm and 82.7 ± 9.2 μm in normal, AGA and TE, respectively. Along with advancement of AGA severity, shedding hair number was generally increased, while hair diameter decreased. The percentage of vellus hairs in AGA was significantly higher than in the normal and TE groups (8.3 ± 6.6% vs 1.0 ± 1.6% and 1.0 ± 1.0%). The combination of shedding hair number and percentage of vellus hairs had a high diagnostic confidence (AUC = 0.957) to diagnose AGA from normal. Shedding hair number alone showed high confidence to diagnose TE from normal (AUC = 0.999).

CONCLUSION

The non-invasive, easy-to-use RWT established in this study is a valuable tool to evaluate daily shedding hairs, which may be useful in diagnosis, dynamic monitoring of disease progression and treatment efficacy.

Trichodynia and telogen effluvium in COVID-19 patients: Results of an international expert opinion survey on diagnosis and management

BACKGROUND

The cutaneous manifestations of COVID-19 may be useful disease markers and prognostic indicators. Recently, postinfectious telogen effluvium and trichodynia have also been reported.

OBJECTIVE

To evaluate the presence of trichodynia and telogen effluvium in patients with COVID-19 and describe their characteristics in relation to the other signs and symptoms of the disease.

METHODS

Patients with a history of COVID-19 presenting to the clinics of a group of hair experts because of telogen effluvium and/or scalp symptoms were questioned about their hair signs and symptoms in relation to the severity of COVID-19 and associated symptoms.

RESULTS

Data from 128 patients were collected. Telogen effluvium was observed in 66.3% of the patients and trichodynia in 58.4%. Trichodynia was associated with telogen effluvium in 42.4% of the cases and anosmia and ageusia in 66.1% and 44.1% of the cases, respectively. In majority (62.5%) of the patients, the hair signs and symptoms started within the first month after COVID-19 diagnosis, and in 47.8% of the patients, these started after 12 weeks or more.

LIMITATIONS

The recruitment of patients in specialized hair clinics, lack of a control group, and lack of recording of patient comorbidities.

CONCLUSION

The severity of postviral telogen effluvium observed in patients with a history of COVID-19 infection may be influenced by COVID-19 severity. We identified early-onset (<4 weeks) and late-onset (>12 weeks) telogen effluvium.

Identification of Breed Differences in Known and New Fescue Toxicosis Associated Phenotypes in Charolais-and Hereford-Sired Crossbred Beef Cows

Simple Summary

The consumption of toxic fescue has caused significant losses in the U.S. beef industry. Widely accepted symptoms of toxic fescue exposure include the retention of a thick hair coat, tissue necrosis in the extremities, and reduced nutrient absorption. However, there is variability in the severity of these symptoms, both across and within breeds. The objective of this study was to characterize the effect of fescue toxicosis across Hereford- and Charolais-sired cows for known and new fescue stress-associated phenotypes. Results indicated that Hereford cows had a lessened ability to shed their winter coat and regulate body temperature along with lower serum mineral concentrations compared to Charolais cows when exposed to toxic fescue. Differences between and within sire breed in hair shedding were also observed, providing further evidence of genetic variation. This study provides evidence of variability in the fescue toxicosis that is potentially useful for genetic selection to reduce fescue stress and characterizes effects on pregnant cows which may impact calves in utero.

Abstract

Beef cattle phenotypes are affected by the consumption of toxic fescue. Toxic fescue’s impact is dependent on heat stress and breed composition, with genetic variability for robustness to toxin exposure believed to exist within and across breeds. The study objective was to characterize the effect of fescue toxicosis across breeds for known and novel heat and fescue stress-associated phenotypes. One-hundred crossbred fall-calving Charolais- and Hereford-sired cows of parities 1–3 were allocated to graze either toxic fescue (n = 50), non-toxic fescue (n = 25), or a rotation between toxic and non-toxic fescue (n = 25) for 156 days. Phenotypes impacted by breed (genetics) included hair coat score (p < 0.0001), hair reduction/shedding rate (p < 0.05), rectal temperature (RT) (p < 0.0001), vaginal temperature (p < 0.05), serum phosphorus concentration (p < 0.02) and respiration rate (RR) (p < 0.003). Cows on toxic fescue experienced reduced hair shedding efficacy (p < 0.0001), higher vaginal temperatures (p < 0.0001), increased systolic blood pressure (p < 0.04), increased RR (p < 0.0001) and reduced average daily gain (p < 0.0001), compared to cows grazing non-toxic fescue. Calves born from cows with higher RT during the last third of gestation had higher RT at weaning (p < 0.02), indicating potential physiological effects of in utero heat stress. The study indicates that beef cows exhibit variable responses to toxic fescue within and across breeds which may impact future calf phenotypes.

Scalp application of antioxidants improves scalp condition and reduces hair shedding in a 24-week randomized, double-blind, placebo-controlled clinical trial

OBJECTIVE

Increasing hair fullness is a global unmet need for many men and women. An approach to the problem is to decrease hair fall or shedding by reducing scalp stratum corneum oxidation and barrier damage to increase hair retention. This study evaluated a combination of functional antioxidants and barrier-enhancing cosmetic ingredients to improve scalp condition thereby enabling stronger hair anchorage and longer retention.

METHODS

Male and female subjects with normal scalp condition and self-perceived hair thinning participated in a 24-week, double-blind, placebo-controlled, randomized clinical study assessing either a regimen of treatment shampoo and leave-on treatment containing functional antioxidant and barrier-enhancing agents or an identical placebo chassis shampoo control. The functional ingredients were piroctone olamine, zinc pyrithione, zinc carbonate, niacinamide, panthenol and caffeine. At baseline and after 8, 16 and 24 weeks of product use, several measurements were taken: hair shedding, total hair count (by phototrichogram), hair samples, TEWL and evaluation of biomarkers of scalp and hair conditions. Subjects also completed self-assessment questionnaires.

RESULTS

Statistically significant effects for functional ingredient-containing treatment regimen versus a placebo control shampoo formulation were observed for reduced hair shedding, increased total hair count, reduced TEWL and improvement in scalp biomarker values. Subjects also noticed these improvements assessed via self-assessment questionnaires.

CONCLUSIONS

These results establish that the use of functional antioxidant and barrier-enhancing agents to further improve scalp condition can enable a reduction in hair shedding and thus an increase in perceived hair fullness. The underlying improvements in scalp condition suggest the hair benefits were achieved as a result of improved scalp skin barrier and scalp condition leading to a viable preventative approach for hair thinning.

Scalp application of the antioxidant piroctone olamine reduces hair shedding in an 8-week randomized, double-blind, placebo-controlled clinical study

OBJECTIVE

Increasing scalp hair fullness is a global unmet consumer need. An approach to decrease hair shedding by reducing scalp stratum corneum oxidation via a combination of antioxidant and barrier-enhancing technologies has been previously demonstrated. The purpose of this study was to test the effectiveness of the individual antioxidant piroctone olamine in two different product forms (shampoo or leave-on product) for activity to improve hair retention.

METHODS

Female subjects with self-perceived hair thinning participated in an 8-week, double-blind, placebo-controlled, randomized clinical study to evaluate either a piroctone olamine (PO) containing shampoo or a PO containing leave on treatment, each relative to their corresponding placebo formulation Too many periods. Results for phototrichograms, TEWL, and biomarker analysis of scalp condition for the shampoo treatments are discussed. Phototrichogram results are shared for the assessment of the leave on treatment.

RESULTS

Statistically significant increases in hair amount were observed by phototrichogram after use of both PO-containing products versus placebo formulations. The PO shampoo treatment also significantly decreased oxidative stress on the hair and scalp, and improved scalp condition as assessed by TEWL and scalp biomarker values.

CONCLUSION

These results illustrate the effectiveness of a cosmetic antioxidant to improve scalp condition thereby improving hair retention. The observed improvements in scalp condition are consistent with previous reports with other antioxidant technologies and suggest that the hair retention effect was achieved by preventing oxidative damage to the scalp.

Telogen effluvium associated with COVID-19 infection

Telogen effluvium (TE) is characterized by diffuse hair shedding 2‐3 months after a stressor, and COVID‐19 infection is potentially one such stressor. Those who were infected with the virus were under immense psychosocial and physiologic stress. We retrospectively reviewed electronic medical records of 552 patients who were evaluated by a Henry Ford Health System dermatologist between February 2020 and September 2020 and had a diagnosis of COVID‐19 infection. Ten patients were identified with TE attributed to COVID‐19 infection and described their presentations as a case series. For the ten patients selected, the mean age was 48.5 years old and 90% were female. Six of the patients were Black, one Middle Eastern, and three White. On average, the hair shedding began 50 days after the first symptom of COVID‐19 infection. About 80% of these patients were treated with antibiotics, systemic corticosteroids, and/or hydroxychloroquine for their COVID‐19 infection and 70% were hospitalized. The presentations of these patients suggest that COVID‐19 infection may be a significant trigger of TE. TE caused by hydroxychloroquine, azithromycin or other medications cannot be ruled out, and the global pandemic itself is a source of psychosocial stress. Further studies will be needed to understand the long‐term prevalence and prognosis of TE associated with COVID‐19 infection.

Styling without shedding: Novel topical formula reduces hair shedding by contracting the arrector pili muscle

Approximately 40% of women experience excessive hair shedding during styling (e.g., hair brushing). Previously, we demonstrated that topically applied phenylephrine, a potent α₁ adrenergic receptor agonist, can be used to contract the arrector pili muscle of the follicular unit; thus, increasing the force required to pluck hair and reducing shedding during brushing. While demonstrating efficacy, phenylephrine has several drawbacks when applied to the scalp, including the possibility cardiovascular events. We hypothesized that a high concentration of a weak α₁ agonist would allow for: (a) rapid penetration through the stratum corneum eliciting a quick response; (b) a low probability of cardiac adverse events owing to the low receptor binding affinity; and (c) an efficacy of the weak α₁ agonist similar to that of phenylephrine at the local site of application. Accordingly, we developed a novel topical solution, AB-102, containing a high concentration of a weak α₁ agonist. Several studies were conducted to test the safety and efficacy of AB-102. In a dose escalating safety study, utilizing a wearable holter monitor, we observed no cardiac or hemodynamic adverse events. In addition, in a controlled efficacy study, AB-102 reduced the number of hairs shed during brushing by up to 77% (average of 38%).

Protease activity, localization and inhibition in the human hair follicle

Objective

In humans, the process of hair shedding, referred to as exogen, is believed to occur independently of the other hair cycle phases. Although the actual mechanisms involved in hair shedding are not fully known, it has been hypothesized that the processes leading to the final step of hair shedding may be driven by proteases and/or protease inhibitor activity. In this study, we investigated the presence of proteases and protease activity in naturally shed human hairs and assessed enzyme inhibition activity of test materials.

Methods

We measured enzyme activity using a fluorescence-based assay and protein localization by indirect immunohistochemistry (IHC). We also developed an ex vivo skin model for measuring the force required to pull hair fibres from skin.

Results

Our data demonstrate the presence of protease activity in the tissue material surrounding club roots. We also demonstrated the localization of specific serine protease protein expression in human hair follicle by IHC. These data provide evidence demonstrating the presence of proteases around the hair club roots, which may play a role during exogen. We further tested the hypothesis that a novel protease inhibitor system (combination of Trichogen® and climbazole) could inhibit protease activity in hair fibre club root extracts collected from a range of ethnic groups (UK, Brazil, China, first-generation Mexicans in the USA, Thailand and Turkey) in both males and females. Furthermore, we demonstrated that this combination is capable of increasing the force required to remove hair in an ex vivo skin model system.

Conclusion

These studies indicate the presence of proteolytic activity in the tissue surrounding the human hair club root and show that it is possible to inhibit this activity with a combination of Trichogen® and climbazole. This technology may have potential to reduce excessive hair shedding.

Résumé