Cutaneous application of α-methylspermidine activates the growth of resting hair follicles in mice

Recent studies using transgenic animals have revealed a crucial role for polyamines in the development and the growth of skin and hair follicles. In mammals, the growth of hair is characterized by three main cyclic phases of transformation, including a rapid growth phase (anagen), an apoptosis-driven regression phase (catagen) and a relatively quiescent resting phase (telogen). The polyamine pool during the anagen phase is higher than in telogen and catagen phases. In this study, we used α-methylspermidine, a metabolically stable polyamine analog, to artificially elevate the polyamine pool during telogen. This manipulation was sufficient to induce hair growth in telogen phase mice after 2 weeks of daily topical application. The application site was characterized by typical features of anagen, such as pigmentation, growing hair follicles, proliferation of follicular keratinocytes and upregulation of β-catenin. The analog penetrated the protective epidermal layer of the skin and could be detected in dermis. The natural polyamines were partially replaced by the analog in the application site. However, the combined pool of natural spermidine and α-methylspermidine exceeded the physiological spermidine pool in telogen phase skin. These results highlight the role of polyamines in hair cycle regulation and show that it is possible to control the process of hair growth using physiologically stable polyamine analogs.     

Quick-freeze,deep-etch visualization of the ‘cytoskeletal spring’ of cochlear outer hair cells

Summary The lateral membrane system of the cochlear outer hair cell, consisting of the lateral plasma membrane, pillars, filamentous lattice and subsurface cisternae, is considered to be involved in the contractile movement of the isolated cochlear outer hair cell. The filamentous lattice, called the cytoskeletal spring, has been identified in the demembranated cochlear outer hair cell treated with the detergent Triton X-100. In this study, the quick-freeze, deep-etch method was applied to demonstrate the three-dimensional organization of both the filamentous and membranous structures of the lateral membrane system of cochlear outer hair cells. Treatment with saponin revealed that the inner leaflet of the lateral plasma membrane of the cochlear outer hair cell possesses more membrane particles than the outer leaflets, and that the pillars are closely associated with membrane particles in the inner leaflet of the lateral membrane. The presence of filamentous bridges between the filamentous lattice and the subsurface cisternae was also detected. We propose that the lateral membrane system in the cochlear outer hair cell may play an important role in the tuning mechanisms within the cochlea in normal hearing.     

Is a "color effect" demonstrated for hair analysis of carbamazepine?

Psillakis et al. have reported on the concentration of carbamazepine recovered from hair samples collected from patients receiving this anti-seizure medication under medical supervision and determined that their was a high correlation between dose and quantitation of recovered analyte. The analyte was identified by two techniques, FPIA (Abbott TDx) and HPLC and the correlation was high for both procedures. In the literature on hair analysis some have suggested that analyte concentration in hair is critically dependent on hair color. In reporting their data Psillakis et al. reported the hair color of each patient but made no attempt to analyze their results in relation to color. This article performs a secondary analysis of the Psillakis et al. data in order to determine whether there is a hair color effect discernible in the recovery of carbamazepine from hair. Analysis of this data set for both the FPIA and HPLC by one-way analysis of variance fails to identify a color effect at p = .05. Weighting the data for per-patient dosage values fails to discern a color effect. Examination of all possible two-color comparisons also fails to identify a statistically significant effect for any subset of combinations. These data suggest that carbamazepine does not exhibit a color effect when using either FPIA or HPLC assay methods.     

Differential response of epithelial stem cell populations in hair follicles to TGF-β signaling

Epidermal stem cells residing in different locations in the skin continuously self-renew and differentiate into distinct cell lineages to maintain skin homeostasis during postnatal life. Murine epidermal stem cells located at the bulge region are responsible for replenishing the hair lineage, while the stem cells at the isthmus regenerate interfollicular epidermis and sebaceous glands. In vitro cell culture and in vivo animal studies have implicated TGF-β signaling in the maintenance of epidermal and hair cycle homeostasis. Here, we employed a triple transgenic animal model that utilizes a combined Cre/loxP and rtTA/TRE system to allow inducible and reversible inhibition of TGF-β signaling in hair follicle lineages and suprabasal layer of the epidermis. Using this animal model, we have analyzed the role of TGF-β signaling in distinct phases of the hair cycle. Transient abrogation of TGF-β signaling does not prevent catagen progression; however, it induces aberrant proliferation and differentiation of isthmus stem cells to epidermis and sebocyte lineages and a blockade in anagen re-entry as well as results in an incomplete hair shaft development. Moreover, ablation of TGF-β signaling during anagen leads to increased apoptosis in the secondary hair germ and bulb matrix cells. Blocking of TGF-β signaling in bulge stem cell cultures abolishes their colony-forming ability, suggesting that TGF-β signaling is required for the maintenance of bulge stem cells. At the molecular level, inhibition of TGF-β signaling results in a decrease in both Lrig1-expressing isthmus stem cells and Lrg5-expressing bulge stem cells, which may account for the phenotypes seen in our animal model. These data strongly suggest that TGF-β signaling plays an important role in regulating the proliferation, differentiation, and apoptosis of distinct epithelial stem cell populations in hair follicles.     

Regeneration of the tibia and somatotopy of regenerated hair sensilla in Schistocerca gregaria (Forskål)

After injury many arthropods are able to regenerate lost body parts and their innervation. Here, regeneration was studied in the desert locust Schistocerca gregaria after amputation of the midleg tibia and tarsus in the first larval instar. A regenerate was formed first in the third larval instar and it increased in size with each larval moult. The regenerate was always unsegmented and remained much shorter than the intact leg parts. The growth rate was initially rather high and decreased thereafter to that of intact parts. The amputation also influenced the growth rate of proximal leg parts (femur and trochanter) resulting in shortened leg segments. The regenerate carried many sense organs like trichoid sensilla and canal sensilla. The primary mechanosensory neurons of the trichoid sensilla projected somatotopically into the mesothoracic ganglion. A comparison of these projections from intact leg segments and regenerates showed a regrow into the target neuropil areas and a restoration of the somatotopy. Intact sensilla on the injured leg and regenerated sensilla expanded their central projections lateral-medially.     

Detection without deflection? A hypothesis for direct sensing of sound pressure by hair cells

It is widely thought that organisms detect sound by sensing the deflection of hair-like projections, the stereocilia, at the apex of hair cells. In the case of mammals, the standard interpretation is that hair cells in the cochlea respond to deflection of stereocilia induced by motion generated by a hydrodynamic travelling wave. But in the light of persistent anomalies, an alternative hypothesis seems to have some merit: that sensing cells (in particular the outer hair cells) may, at least at low intensities, be reacting to a different stimulus — the rapid pressure wave that sweeps through the cochlear fluids at the speed of sound in water. This would explain why fast responses are sometimes seen before the peak of the travelling wave. Yet how could cells directly sense fluid pressure? Here, a model is constructed of the outer hair cell as a pressure vessel able to sense pressure variations across its cuticular pore, and this ‘fontanelle’ model, based on the sensing action of the basal body at this compliant spot, could explain the observed anomalies. Moreover, the fontanelle model can be applied to a wide range of other organisms, suggesting that direct pressure detection is a general mode of sensing complementary to stereociliar displacement.     

New method of derivatization and headspace solid-phase microextraction for gas chromatographic–mass spectrometric analysis of amphetamines in hair

A simple method for hair analysis of methamphetamine (MAMP) and amphetamine (AMP) by gas chromatography–mass spectrometry (GC–MS) was developed using simultaneous headspace solid-phase microextraction (HS-SPME) with derivatization. After alkaline-digestion of hair, the analytes derivatized with heptafluoro-n-butyryl chloride were adsorbed on a polydimethylsiloxane-coated fiber by HS-SPME and analyzed by GC–MS. Their mass spectra were, respectively, observable at 1 ng per sample. The standard curves in the range of 0.1–100 ng were linear. The intra-day coefficients of variation at each 0.5 ng were 12.5% for AMP and 3.8% for MAMP. The applicability of this method was demonstrated in some case studies.     

Effects of low-dose γ-rays on the embryonic development of mouse melanoblasts and melanocytes in the epidermis and hair bulbs

The effects of low-dose γ-rays on the embryonic development of animal cells are not well studied. The mouse melanocyte is a good model to study the effects of low-dose γ-rays on the development of animal cells, as it possesses visible pigment (melanin) as a differentiation marker. The aim of this study is to investigate in detail the effects of low-dose γ-rays on embryonic development of mouse melanoblasts and melanocytes in the epidermis and hair bulbs at cellular level. Pregnant females of C57BL/10J mice at nine days of gestation were whole-body irradiated with a single acute dose of γrays (0.1, 0.25, 0.5, and 0.75 Gy), and the effects of γ-rays were studied by scoring changes in the development of epidermal melanoblasts and melanocytes, hair follicles, and hair bulb melanocytes at 18 days in gestation. The number of epidermal melanoblasts and melanocytes, hair follicles, and hair bulb melanocytes in the dorsal and ventral skins was markedly decreased even at 0.1 Gy-treated embryos (P < 0.001), and gradually decreased as dose increased. The effects on the ventral skin were greater than those on the dorsal skin. The dramatic reduction in the number of melanocytes compared to melanoblasts was observed in the ventral skin, but not in the dorsal skin. These results suggest that low-dose γ-rays provoke the death of melanoblasts and melanocytes, or inhibit the proliferation and differentiation of melanoblasts and melanocytes, even at the low dose.     

Genetic diversity and assessment of 23 microsatellite markers for parentage testing of Santa Inês hair sheep in Brazil

Santa Inês is the most common hair sheep breed in Brazil and probably has the highest genetic diversity among sheep breeds in this country. Successful breeding programs for Brazilian sheep breeds are not common for various reasons, including a lack of control of parentage in the flocks. We developed an allele frequency database for 23 STR loci for the Santa Inês breed based on 285 animals sampled from five populations distributed across the central-western and north-eastern regions of Brazil. The marker set included seven microsatellites used in the 2011 International Society for Animal Genetics sheep genotyping comparison tests and all eight microsatellites currently approved by the Brazilian Agricultural Ministry laboratory accreditation guidelines for sheep identification. The microsatellites had an average of 10 alleles and a mean expected heterozygosity of 0.745. Combined paternity exclusion probabilities when no parent or one parent was known were >99.99%. A small proportion (5.8%) of the existing genetic variation was found to be among the Santa Inês populations, possibly derived from genetic drift and selection. We found that the marker panel proposed by the Agricultural Ministry, although generally useful, should be enhanced by including more markers for improved exclusionary power in parentage testing. This database provides a useful tool for parentage testing of this major Brazilian breed, contributing to improved management and breeding of existing herds.     

Laser hair removal: where are we now?

The hair removal market is evolving rapidly. The goal has always been long-term epilation. Success is dependent on understanding hair biology and physiology and on knowledge of laser physics, skin optics, and tissue preservation with respect to these emerging laser technologies. These topics will be reviewed, as will specific categories of laser systems in the hair removal arena and the clinical aspects of laser hair removal today.     

Effects of whole body vibration on outer hair cells’ hearing response to distortion product otoacoustic emissions

Whole body vibration (WBV) is one of the most vexing problems in industries. There is a debate about the effect of WBV exposure on hearing system as vibration-induced hearing loss. The purpose of this study was to investigate outer hair cells' (OHCs') hearing response hearing response to distortion product otoacoustic emissions (DPOAEs) in rabbits exposed to WBV. It was hypothesized that the DPOAE response amplitudes (A(dp)) in rabbits exposed to WBV would be lower than those in control rabbits not exposed to WBV. New Zealand white (NZW) rabbits as vibration group (n = 6, exposed to WBV in the z-axis at 4-8 Hz and 1.0 ms(-2) root mean square for 8 h per day during five consecutive days) and NZW rabbits as control group (n = 6, not exposed to any WBV) were participated. A(dp) and noise floor levels (L(nf)) were examined on three occasions: day 0 (i.e., baseline), day 8 (i.e., immediately 1 h after exposure), and day 11 (i.e., 72 h following exposure) with f(2) frequencies ranging from 500 to 10,000 Hz and primaries L(1) and L(2) levels of 65 and 55 dB sound pressure level, respectively. Main effects were statistically found to be significant for group, time, and frequency (p < 0.05). DPOAE amplitudes were significantly larger for rabbits exposed to WBV, larger on day 8 and larger for mid to high f(2) frequencies (at and above 5,888.50 Hz). Main effects were not statistically found to be significant for ear (p > 0.05). Also, four statistically significant interactions including time by ear, time by frequency, group by frequency, and group by time were detected (p < 0.05). Contrary to the main hypothesis, DPOAE amplitudes were significantly larger for rabbits exposed to WBV. WBV exposure significantly led to enhanced mean A(dp) at mid to high frequencies rather than at low ones.     

Thyroid hormone receptor α1 is a critical regulator for the expression of ion channels during final differentiation of outer hair cells

Cochlear outer hair cells (OHCs) terminally differentiate prior to the onset of hearing. During this time period, thyroid hormone (TH) dramatically influences inner ear development. It has been shown recently that TH enhances the expression of the motor protein prestin via liganded TH receptor β (TRβ) while in contrast the expression of the potassium channel KCNQ4 is repressed by unliganded TRα1. These different mechanisms of TH regulation by TRα1 or TRβ prompted us to analyse other ion channels that are required for the final differentiation of OHCs. We analysed the onset of expression of the Ca²⁺ channel Ca_V1.3, and the K⁺ channels SK2 and BK and correlated the results with the regulation via TRα1 or TRβ. The data support the hypothesis that proteins expressed in rodents prior to or briefly after birth like Ca_V1.3 and prestin are either independent of TH (e.g. Ca_V1.3) or enhanced through TRβ (e.g. prestin). In contrast, proteins expressed in rodents later than P6 like KCNQ4 (∼P6), SK2 (∼P9) and BK (∼P11) are repressed through TRα1. We hypothesise that the precise regulation of expression of the latter genes requires a critical local TH level to overcome the TRα1 repression. Harald Winter and Claudia Braig contributed equally to this work.     

Microstructural characteristics of hair of pleistocene mummy of “Bilibino horse” <Emphasis Type="Italic">Equus</Emphasis> sp.

The microstructure of hair of all mummified horses found in Northeastern Siberia has been studied for the first time in a comparative aspect by means of light optical and electron microscopy techniques. The possibility of using hair of horse mummies of different geological ages for a comparative analysis has been demonstrated. No fundamental differences were found in hair microstructure between the mummy of the “Bilibino” horse Equus sp. (geological age 58500 years) and mummified remains of the Lena horse Equus lenesis Russanov, 1968 (geological age 38 5000–29 500 years), which suggests their close relationship. It has been shown that morphological adaptations in the structure of the equine hair coat formed during the Pleistocene and Holocene under the specific climate conditions of Northeastern Siberia.     

Have we found the tip link,transduction channel,and gating spring of the hair cell?

Recent reports have offered candidates for key components of the apparatus used for mechanotransduction in hair cells. TRPA1 and cadherin 23 have been proposed to be the transduction channel and component of the tip link, respectively; moreover, ankyrin repeats in TRPA1 have been proposed to be the gating spring. Although these are excellent candidates for the three components, definitive experiments supporting each identification have yet to be performed.