Temperature regulation in horses during exercise and recovery in a cool environment

BACKGROUND

Clipping the winter coat in horses is done to improve heat dissipation during exercise and make grooming easier. It is often combined with blanketing to keep the horse warm. The aims of the present study were to investigate how clipping and the use of blankets affect thermoregulation during exercise and recovery in horses.

METHODS

One Gotland pony, one New Forest pony, and one warm-blooded horse exercised one after the other on a 6450 m long track. The horses walked, trotted and cantered according to a predetermined scheme, which took about 50 minutes including three stops. The scheme was repeated on five consecutive days when horses were: 1) unclipped 2) unclipped + blanket during recovery, 3) left or right side clipped, 4) clipped, and 5) clipped + riding blanket + blanket during recovery. Heart rate (HR) was measured with telemetry, respiratory rate (RR) by counting flank contractions, skin temperatures by thermistor probes, and rectal temperature with a digital thermometer. Skin wetness (SW) was estimated by ocular inspection (dripping = 5, dry = 0).

RESULTS

Mean outdoor temperature varied from -1.1 to - 8.7°C. HR increased progressively during exercise with no difference between treatments. Maximum RR was 77 ± 30 breaths/min (unclipped) and 49 ± 27 breaths/min (clipped). The lowest skin temperature was 17.5 ± 2.7°C in a hind leg during exercise, which increased to 34.5 ± 0.1°C during recovery. Rectal temperature was elevated during recovery in unclipped, but not in clipped horses and skin temperature at base of tail was elevated during recovery except in unclipped horses without blanket. Moisture after exercise scored 3.2 ± 0.8 in unclipped and zero in clipped horses.

DISCUSSION AND CONCLUSION

Leg skin temperature initially dropped at onset of exercise in clipped horses, and then increased after about 30 minutes due to internal heat from the working muscles. These changes were not significant when clipped horses had riding blankets, whereas unclipped horses became overheated as judged from respiratory rate and elevated rectal temperature. Providing clipped horses with blankets dampened the changes in leg skin temperature during exercise.

The cell cycle regulator protein 14-3-3σ is essential for hair follicle integrity and epidermal homeostasis

The 14-3-3σ (Stratifin; Sfn) is a cell cycle regulator intimately involved in the program of epithelial keratinization. 14-3-3σ is unique in that it is expressed primarily in epithelial cells and is frequently silenced in epithelial cancers. Despite its well-documented role as a cell cycle regulator and as a tumor suppressor, the function of 14-3-3σ in the intricate balance of proliferation and differentiation in epithelial development is poorly understood. A mutation in 14-3-3σ was found to be responsible for the repeated epilation (Er) phenotype. It has previously been shown that Sfn(+/Er) mice are characterized by repeated hair loss and regrowth, whereas Sfn(Er/Er) mice die at birth displaying severe oral fusions and limb abnormalities as a result of defects in keratinizing epithelia. Here we show that mice heterozygous for the 14-3-3σ mutation have severe defects in hair shaft differentiation, resulting in destruction of the hair shaft during morphogenesis. Furthermore, we report that the interfollicular epidermis and sebaceous glands are hyperproliferative, coincident with expanded nuclear Yap1 (Yes-associated protein 1)--a critical modulator of epidermal stem cell proliferation. We also report that hair follicle stem cells in the bulge cycle abnormally, raising important questions as to the role of 14-3-3σ in the bulge.

[Implantation of newborn mice skin cells with chamber method to construct a model of hair follicle development]

OBJECTIVE

To construct a convenient, reliable and visual model of hair follicle development to test the hair-inductive potential of follicular cells and investigate the molecular mechanism regulating hair follicle morphogenesis and cycling.

METHODS

An open chamber was transplanted into the nude mice dorsal skin, dermal and epidermal cells isolated from newborn C57BL/6 mice skin were mixed at a specific ratio and then injected into the chamber together, 1 week after transplantation, the chamber was removed, and then, hair formation and regeneration after hair plucking was observed.

RESULTS

1 week after cells implantation, the wound was moist without apparent contraction and among that pink and translucent tissue was formed. 2 weeks after implantation, the wound healed completely. 3 weeks after implantation, black hair grew from the skin was observed. 4 weeks after implantation, thick and black hair grew from the skin vertically. Completely developed structure of hair follicle was observed with paraffin section and HE staining. 1 week after plucking, new hair had regrown. The ratio of cell component was varied, whereas the other component was fixed at 1 x 10(7) cells. When the number of epidermal cells was reduced to 1 x 10(6) cells, the efficiency of hair follicle reconstitution was mostly unchanged. On the other hand, the density of newly formed hair was diminished considerably by reducing the number of dermal cells to 5 x 10(6) cells or lower. Neither epidermal cells nor dermal cells transplanted alone formed hair follicle.

CONCLUSIONS

Newborn mice skin cells transplanted by chamber method can construct a complete model of hair follicle development, which can be used to test the hair-inductive potential of follicular cells and investigate the molecular mechanism regulating hair follicle morphogenesis and cycling.

Alopecia: a review of laser and light therapies

Since the 1980s, laser technology has become increasingly popular to treat a variety of cutaneous conditions. Its successful use as an epilator comes with the rare but interesting side effect of paradoxical hypertrichosis. In this review, we summarize cases describing hair growth after photoepilation, as well as studies testing laser and light sources as treatment for alopecia, particularly androgenetic alopecia and alopecia areata. We also discuss the possible biologic mechanisms by which phototherapy induces hair regeneration.

The frizzled/stan pathway and planar cell polarity in the Drosophila wing

Drosophila has been the key model system for studies on planar cell polarity (PCP). The rich morphology of the insect exoskeleton contains many structures that display PCP. Among these are the trichomes (cuticular hairs) that cover much of the exoskeleton, sensory bristles, and ommatidia. Many genes have been identified that must function for the development of normal PCP. Among these are the genes that comprise the frizzled/starry night (fz/stan) and dachsous/fat pathways. The mechanisms that underlie the function of the fz/stan pathway are best understood. All of the protein products of these genes accumulate asymmetrically in wing cells and there is good evidence that this involves local intercellular signaling between protein complexes on the distal edge of one cell and the juxtaposed proximal edge of its neighbor. It is thought that a feedback system, directed transport, and stabilizing protein-protein interactions mediate the formation of distal and proximal protein complexes. These complexes appear to recruit downstream proteins that function to spatially restrict the activation of the cytoskeleton in wing cells. This leads to the formation of the array of distally pointing hairs found on wings.

Hair breakage by combing and brushing--a comment on: T. A. Evans and K. Park, A statistical analysis of hair breakage. II. Repeated grooming experiments, J. Cosmet. Sci., 41, 439-456 (2010)

Literature dealing with the mechanisms of hair breakage in combing and brushing published so far has been reviewed as a background for the critical evaluation of the method and data analysis of the paper "Statistical Analysis of Hair Breakage. II" by Evans and Park (1). Accumulated knowledge about hair breakage in these grooming processes indicates that hair breakage in combing and brushing results from tangling, looping, knotting, and impact loading. Fatiguing, though responsible for some weakening of the fiber in the grooming process, it is unlikely to be a significant factor in hair breakage in combing and brushing.

Qualification of an automated device to objectively assess the effect of hair care products on hair shine

The authors developed and qualified an automated routine screening tool to quantify hair shine. This tool is able to separately record individual properties of hair shine such as specular reflection and multiple reflection, as well as additional features such as sparkle, parallelism of hair fibers, and hair color, which strongly affect the subjective ranking by individual readers. A side-by-side comparison of different hair care and styling products with regard to hair shine using the automated screening tool in parallel with standard panel assessment showed that the automated system provides an almost identical ranking and the same statistical significances as the panel assessment. Provided stringent stratification of hair fibers for color and parallelism, the automated tool competes favorably with panel assessments of hair shine. In this case, data generated with the opsira Shine-Box are clearly superior over data generated by panel assessment in terms of reliability and repeatability, workload and time consumption, and sensitivity and specificity to detect differences after shampoo, conditioner, and leave-in treatment. The automated tool is therefore well suited to replace standard panel assessments in claim support, at least as a screening tool. A further advantage of the automated system over panel assessments is the fact that absolute numeric values are generated for a given hair care product, whereas panel assessments can only give rankings of a series of hair care products included in the same study. Thus, the absolute numeric data generated with the automated system allow comparison of hair care products between studies or at different time points after treatment.

Biologic rhythms derived from Siberian mammoths' hairs

Hair is preserved for millennia in permafrost; it enshrines a record of biologic rhythms and offers a glimpse at chronobiology as it was in extinct animals. Here we compare biologic rhythms gleaned from mammoth's hairs with those of modern human hair. Four mammoths' hairs came from varying locations in Siberia 4600 km, four time zones, apart ranging in age between 18,000 and 20,000 years before present. We used two contemporaneous human hairs for comparison. Power spectra derived from hydrogen isotope ratios along the length of the hairs gave insight into biologic rhythms, which were different in the mammoths depending on location and differed from humans. Hair growth for mammoths was ∼31 cms/year and ∼16 cms/year for humans. Recurrent annual rhythms of slow and fast growth varying from 3.4 weeks/cycles to 8.7 weeks/cycles for slow periods and 1.2 weeks/cycles to 2.2 weeks/cycles for fast periods were identified in mammoth's hairs. The mineral content of mammoth's hairs was measured by electron microprobe analysis (k-ratios), which showed no differences in sulfur amongst the mammoth hairs but significantly more iron then in human hair. The fractal nature of the data derived from the hairs became evident in Mandelbrot sets derived from hydrogen isotope ratios, mineral content and geographic location. Confocal microscopy and scanning electron microscopy showed varied degrees of preservation of the cuticle largely independent of age but not location of the specimens. X-ray fluorescence microprobe and fluorescence computed micro-tomography analyses allowed evaluation of metal distribution and visualization of hollow tubes in the mammoth's hairs. Seasonal variations in iron and copper content combined with spectral analyses gave insights into variation in food intake of the animals. Biologic rhythms gleaned from power spectral plots obtained by modern methods revealed life style and behavior of extinct mega-fauna.

Hair and nails

BACKGROUND

Hair and nails are elements of dermatology that can often be omitted from the dermatological assessment. However, there are common and distressing hair and nail conditions that require diagnosis and management.

OBJECTIVE

This article considers common and important hair and nail presentations to general practice. General and specific conditions will be discussed.

DISCUSSION

Hair conditions may have significant psychological implications. This article considers assessment and management of conditions of too much hair, hair loss or hair in the wrong places. It also considers the common nail conditions seen in general practice and provides a guide to diagnosis and management.

Use of multivariate analyses for determining heat tolerance in Brazilian cattle

Adaptability can be evaluated by the ability of an animal to adjust to environmental conditions and is especially important in extreme weather conditions such as that found in tropical Brazil. A multivariate analysis using physical and physiological traits in exotic (Nellore and Holstein) and naturalized (Junqueira, Curraleira, Mocho Nacional, Crioula Lageana, and Pantaneira) cattle breeds was carried out in the Federal District of Brazil to test and determine which traits are important in the adaptation of animal to heat stress as well as the ability of these traits and statistical techniques to separate the breeds studied. Both physical and physiological traits were measured on three occasions and included body measurements, skin and hair thickness, hair number and length, pigmentation, sweat gland area as well as heart and breathing rates, rectal temperature, sweating rate, and blood parameters. The data underwent multivariate statistical analyses, including cluster, discriminate, and canonical procedures. The tree diagram showed clear distances between the groups studied, and canonical analysis was able to separate individuals in groups. Coat traits explained little variation in physiological parameters. The traits which had higher discriminatory power included packed cell volume, shoulder height, mean corpuscular volume, body length, and heart girth. Morphological and physiological traits were able to discriminate between the breeds tested, with blood and size traits being the most important. More than 80% of animals of all breeds were correctly classified in their genetic group.

Sphere formation restores and confers hair-inducing capacity in cultured mesenchymal cells

Interactions between epithelial and dermal cells are essential for hair follicle morphogenesis and maintenance. In experimental trials of hair regeneration, isolated dermal cells have been shown to possess hair-inducing capacity. However, dermal cells lose this potential immediately after cultivation. Sphere-forming multipotent cells derived from the dermis possess hair-inducing capacity. These previous findings raise the question of whether hair-inducing capacity depends on the identity as dermal cells or the process of sphere formation. To address this issue, we compared the in vitro and in vivo characteristics of two-dimensionally cultured or thereafter sphere formation-induced dermal and lung mesenchymal cells. We show that sphere-forming mesenchymal cells exhibited higher expression of Wnt signalling genes. Sphere-forming cells but not two-dimensionally cultured cells possessed in vivo hair-inducing capacity. These data suggest that various mesenchymal cells attain hair-inducing capacity through the process of sphere formation.

Alopecia in adolescents

It is important for practitioners to accurately diagnose hair loss in adolescents so that prompt and appropriate therapy can be initiated.

Thermal styling: efficacy, convenience, damage tradeoffs

We introduce a simple method to explore the efficacy of thermal styling, By using a temperature gradient curling iron we rapidly explore a range of thermal treatment conditions. The thermodynamic literature on the glass transition in keratin fibers explains the surprisingly limited role of elevated temperature in improvements in the efficacy of holding the styled curvature of the fibers. The onset of damage, however, is strongly temperature dependent. This combination of measurements of damage and efficacy shows the range of conditions over which thermal protection products must be functional.

Proteomic analysis of hair shaft and nail plate

The protein components of living cells in the hair follicle are amenable to study by standard molecular biological techniques, but identifying those in the hair shaft has been problematic until recently. Most of the protein, primarily keratins and keratin associated proteins, can be extracted under denaturing conditions, but 15-20% is intractable due to transglutaminase-mediated cross-linking. Shotgun proteomics now permits identifying >300 constituents of the isopeptide cross-linked proteome and even certain post-translational modifications. The proteins originate from all the intracellular compartments, indicating that the cross-linking process makes effective use of available resources to produce structures with great mechanical stability. Knowing this proteome provides a foundation for correlating defects in hair shaft structure with protein deficiencies. Such investigations can be extended to mouse models of aberrant pelage hair. Thus, inbred mouse strains can be distinguished by their hair proteomes, raising the possibility of similar variation in the human population. The nail plate is also amenable to this shotgun proteomic approach. Providing discrete and noninvasive sampling of the human proteome, these epidermal appendages could have diagnostic utility for certain disease states.

Study of hair surface energy and conditioning

A new test method has been developed to determine surface energy of hair fibers through measurements of contact angles at two hair/liquid interfaces. By measuring changes in surface energy of the same hair fiber before and after a cosmetic treatment, effects of active ingredients and the performance of tested formulations can be evaluated.The establishment of the method is based on Fowkes theory (1,2) described with two components, a dispersive and a non-dispersive component. The non-polar liquid used in this study was diiodomethane, and the polar liquid was benzyl alcohol. A Kruss 100 Tensiometer was used to measure contact angles of hair fibers. Virgin dark brown and regular bleached hairs were treated with selected conditioner formulations. Reductions in combing forces of hair tresses before and after respective treatments were correlated with decreases in average surface energy of hair fibers obtained from the corresponding tresses.Experimental results indicate that the average surface energy of hair fibers treated with conditioners decreases and the hydrophobicity of the hair surface increases, the results correlate well with the reduction in combing forces after respective treatments. This research work provides a new methodology to evaluate/screen conditioning performance of hair care ingredients and formulations for development of better products.

Characterization of hair styling formulations targeted to specific multicultural needs

The ethnic hair care market is large and diverse, with many unmet needs, especially when the definition of ethnic varies as much as the hair does. By examining the variety of hair care raw materials now available, we designed hair styling formulations for targeted benefits such as anti-frizz, conditioning, style control, humidity resistance, UV protection and color loss protection. We have characterized three distinctive hair styling formulations targeted to specific multicultural needs. This has been completed by using standard personal care laboratory evaluations including the Diastron Limited (TM)Miniature Tensile Tester for stiffness, the Bossa Nova Technologies (TM) Shine Instrument, high-humidity curl control, UV exposure, and expert panel evaluations; the results were substantiated using current state-of-the-art analytical tools, including atomic force microscopy and scanning electron microscopy. Results demonstrate that a varied product portfolio is required for such a diverse market segment. Styling products ranging from alcoholic sprays, leave on styling creams or gels and styling curl activators offer performance attributes that can be utilized on a variety of hair types such as Asian, African, Caucasian and Brazilian.

Graying of the human hair follicle

Quality of life in our society depends crucially on healthy aging, a hallmark of which is the graying hair follicle. During anagen melanocyte precursors migrate to the hair bulb to form the pigmentary unit where they mature and synthesize melanin. Melanin is transferred to the hair shaft forming keratinocytes giving the hair its colour. Graying is the process in which distinct mechanisms lead to deterioration of the hair follicle melanocyte population. We briefly review the hair graying process and state that the aging hair follicle is a valid model for tissue specific aging and a promising target to test therapeutic intervention.

A statistical analysis of hair breakage. II. Repeated grooming experiments

The objective of this work was to introduce the idea of analyzing data from repeated brushing and combing experiments on hair in accordance with standard fatigue testing approaches. In mechanical testing terms, the brushing and combing of hair represents a fatiguing process wherein individual strands experience repeated exposure to an external stimulus. Therefore, in accordance with fatiguing principles, one expects a gradual propagation of flaws within individual fibers until, ultimately, catastrophic failure (breakage) results. A previous paper in this series described the modeling of single-fiber fatigue data using the Weibull approach, and, in so doing, introduced the idea of treating fiber breakage as a statistical variable. Here, a grouped Weibull methodology was used to analyze breakage data from repeated brushing and combing experiments. At a top level, the generation of the two Weibull parameters provides a means of characterizing these experiments. However, the real strength of the approach involves the ability to generate survival probability plots that provide predictions as to the likelihood of fiber breakage under different conditions. Therefore, assuming laboratory experiments are a reasonable representation of real-life conditions, it becomes possible to predict breakage rates on actual heads as a function of different habits and practices. It is also shown how the two Weibull parameters, together with information about the number of fibers in the test tresses, allow for the modeling of repeated brushing and combing tests and allow anyone to re-create the experimental outcome for comparison to their own experiences. These principles have been demonstrated using experiments that compare breakage in virgin and chemically damaged hair, while also showing how conditioning treatments provide considerable retardation.

The naked truth: Sphynx and Devon Rex cat breed mutations in KRT71

Hair is a unique structure, characteristic of mammals, controlling body homeostasis, as well as cell and tissue integration. Previous studies in dog, mouse, and rat have identified polymorphisms in Keratin 71 (KRT71) as responsible for the curly/wavy phenotypes. The coding sequence and the 3′ UTR of KRT71 were directly sequenced in randomly bred and pedigreed domestic cats with different pelage mutations, including hairless varieties. A SNP altering a splice site was identified in the Sphynx breed and suggested to be the hairless (hr) allele, and a complex sequence alteration, also causing a splice variation, was identified in the Devon Rex breed and suggested to be the curly (re) allele. The polymorphisms were genotyped in approximately 200 cats. All the Devon Rex were homozygous for the complex alterations and most of the Sphynx were either homozygous for the hr allele or compound heterozygotes with the Devon-associated re allele, suggesting that the phenotypes are a result of the identified SNPs. Two Sphynx carrying the proposed hr mutation did not carry the Devon-associated alteration. No other causative mutations for eight different rexoid and hairless cat phenotypes were identified. The allelic series KRT71⁺ > KRT71^hr > KRT71^re is suggested.

A naturally occurring variant of Hsp90 that is associated with decanalization

The heat shock protein Hsp90 has been the focus of many studies since it was suggested that it acts to mediate the buffering of phenotypic variation. Hsp90-mediated buffering may result in the accumulation of cryptic genetic variation that, when released either as a consequence of environmental or genetic stress, increases the evolvability of a population. Recent studies using laboratory-induced mutations of Hsp90 and/or chemical inhibition to disrupt Hsp90 function confirm that Hsp90 can buffer cryptic genetic variation. We have previously identified a naturally occurring variant in the charged linker region of the Hsp90 gene, and now examine whether this variant is associated with altered levels of trait variability. The variant is associated with the release of cryptic genetic variation for canalized morphological (bristle) traits, but not for uncanalized morphological (wing and bristle) traits, and the effect on canalized traits depends on culture temperature. This suggests that natural genetic variation in Hsp90 may mediate the evolution of canalized morphological traits even if it does not influence the expression of variation for uncanalized traits.

Hair stem cells for bladder regeneration in rats: preliminary results

BACKGROUND

A variety of tissue engineering techniques are currently under development or investigation for bladder augmentation, but so far no approach is clearly superior. The aim of this study was to compare the suitability for cystoplasty augmentation in rats of in vivo implanted acellular bladder matrices (BAM) previously seeded with hair follicle stem cells and that of matrices implanted without the cells.

MATERIALS AND METHODS

The rat hair follicle stem cell line was positive for CD34, p63, and Ki-67. 1 x 10(6) cells from 34 to 40 passages seeded onto nine BAM scaffolds were cultured for one week. Nine other scaffolds were left unseeded. Scaffolds were grafted into a surgically created defect within the anterior bladder wall: nine rats with acellular matrices and nine with cell-seeded BAM. Rats observed for six months were killed in monthly intervals. We performed gross examination, X-ray cystography, and hematoxylin-eosin, cytokine (CK)-7, CK-20, myoglobin, and desmin staining of the excised bladders.

RESULTS

Minimal adhesions were observed and urinary leakage was noted in one case. Two animals died in the acellular group. Rats developed stone disease in bladders reconstructed with acellular BAM. Bladder capacity was similar, but the shape was regular and characteristically oval only in bladders grafted with cell-seeded BAM. Muscle layers in the apical parts of the reconstructed bladder walls were extremely thin in the cases of acellular grafts and thicker in bladders reconstructed with cell-seeded grafts. Muscle layer regeneration was better in the cell-seeded group. Urothelium regenerated in all animals.

CONCLUSIONS

We have shown that hair follicle stem cells may be used for rat bladder wall regeneration.

A computational fluid dynamics model of viscous coupling of hairs

Arrays of arthropod filiform hairs form highly sensitive mechanoreceptor systems capable of detecting minute air disturbances, and it is unclear to what extent individual hairs interact with one another within sensor arrays. We present a computational fluid dynamics model for one or more hairs, coupled to a rigid-body dynamics model, for simulating both biological (e.g., a cricket cercal hair) and artificial MEMS-based systems. The model is used to investigate hair-hair interaction between pairs of hairs and quantify the extent of so-called viscous coupling. The results show that the extent to which hairs are coupled depends on the mounting properties of the hairs and the frequency at which they are driven. In particular, it is shown that for equal length hairs, viscous coupling is suppressed when they are driven near the natural frequency of the undamped system and the damping coefficient at the base is small. Further, for certain configurations, the motion of a hair can be enhanced by the presence of nearby hairs. The usefulness of the model in designing artificial systems is discussed.