Biomechanics of hair fibre growth: A multi-scale modeling approach

Zamil, M. Shafayet; Harland, Duane P.; Fisher, Brian K.; Davis, Michael; Schwartz, James R.; Geitmann, Anja

doi:10.1016/j.jmps.2021.104290

Cited by 6 publications

(4 citation statements)

References 43 publications

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“…While proliferation occurs in the follicular bulb, the remaining pre-emergent hair is considered to be 'dead' [19]. The process of normal fibre elongation post-proliferation can be viewed as a mechanical process [20]. Thus, reducing oxidative stress at the scalp is a means of creating an optimal environment for hair to passively mature normally, achieving optimal quality and anchorage.…”

Section: Introductionmentioning

confidence: 99%

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

Davis

Piliang

Bergfeld

et al. 2021

Intern J of Cosmetic Sci

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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 leaveon 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.

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Section: Introductionmentioning

confidence: 99%

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

Davis

Piliang

Bergfeld

et al. 2021

Intern J of Cosmetic Sci

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“…Along the axis of hair growth, there are natural changes in local density within the shaft and surrounding sheaths associated with keratinization via oxidation and crosslinking of the keratin and cornification resulting in turgor loss. 87,88 Even before keratinization, polymerisation of keratins from dimers to unit-length filaments (the monomer of a KIF) is thought to release water molecules. 89 Because water and its flow is important to hair growth, dehydration-induced morphological degradation 90 is of particular concern for follicles.…”

Section: Dehydr Ation and Free Ze Subs Tituti Onmentioning

confidence: 99%

“…It is during this dehydration process, effectively a solvent exchange, where the hierarchical structure of the hair follicle can be a potential problem. Along the axis of hair growth, there are natural changes in local density within the shaft and surrounding sheaths associated with keratinization via oxidation and cross‐linking of the keratin and cornification resulting in turgor loss 87,88 . Even before keratinization, polymerisation of keratins from dimers to unit‐length filaments (the monomer of a KIF) is thought to release water molecules 89 .…”

Section: Dehydration and Freeze Substitutionmentioning

confidence: 99%

Processing hair follicles for transmission electron microscopy

Velamoor

Mitchell

Bostina

et al. 2021

Experimental Dermatology

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Transmission electron microscopy (TEM) has greatly advanced our knowledge of hair growth and follicle morphogenesis, but complex preparations such as fixation, dehydration and embedding compromise ultrastructure. While recent developments with cryofixation have been shown to preserve the ultrastructure of biological materials close to native state, they do have limitations. This review will focus on each stage of the TEM sample preparation process and their effects on the structural integrity of follicles.

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“…The coordinated series of physical-chemical changes enable the lengthening and strengthening of the hair fibre. This can be modelled as a mechanical process in which the physical forces due to hardening and water transport explain the resultant fibre progression towards the scalp surface [6].…”

Section: Introductionmentioning

confidence: 99%

Role of scalp health in achieving optimal hair growth and retention

Tosti

Schwartz

2021

Intern J of Cosmetic Sci

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We have conducted a thorough review of the literature to assess the evidence for supporting a cause-and-effect linkage between scalp condition and resultant hair condition.Over 20 epidemiological studies have been published covering a wide range of abnormal scalp conditions in which consequent impacts to the hair have been documented. A treatment study was conducted to demonstrate not only that impaired scalp condition led to impaired hair quality but that the impacts to hair are reversible upon normalization of the scalp condition. A proposed explanation involves the impact of scalp oxidative stress, which is part of the etiology of these scalp conditions as well as normal aging, in interfering with the normal keratinization of the pre-emergent hair cuticle. This perturbed cuticle impedes normal fiber anchorage and emerges more brittle and fragile than normal cuticle leading to accelerated physical degradation, mirroring the effects of chronological aging of the hair fiber. The consequences of the rapid cuticle degradation result in hair that is more vulnerable to mechanical insults and compromised overall quality. RésuméNous avons mené un examen approfondi de la littérature médicale pour évaluer les preuves étayant un lien de cause à effet entre l'état du cuir chevelu et celui des cheveux. Plus de 20 études épidémiologiques ont été publiées, couvrant un large éventail d'affections du cuir chevelu pour lesquelles des impacts conséquents sur les cheveux ont été documentés. Une étude de traitement a été menée pour démontrer non seulement qu'une altération du cuir chevelu entraînait une altération de la qualité des cheveux, mais aussi que les impacts sur les cheveux étaient réversibles après normalisation de l'état du cuir chevelu. Une explication proposée inclut l'impact du stress oxydatif sur le cuir chevelu, qui fait partie de l'étiologie de ces affections du cuir chevelu ainsi que du vieillissement normal, en interférant avec la kératinisation normale de la cuticule du cheveu à son point d'émergence. Cette cuticule perturbée gêne l'ancrage normal des fibres et fait émerger des cuticules plus fragiles et friables que la normale, entraînant une dégradation physique accélérée, reflet des effets du vieillissement chronologique des fibres capillaires. La dégradation rapide de la cuticule rend les cheveux plus vulnérables aux agressions mécaniques et compromet leur qualité globale.

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Biomechanics of hair fibre growth: A multi-scale modeling approach

Cited by 6 publications

References 43 publications

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

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

Processing hair follicles for transmission electron microscopy

Role of scalp health in achieving optimal hair growth and retention

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