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At least 325 records · Page 18Linked to original sources
PubMed2005

Hair bundle heights in the utricle: differences between macular locations and hair cell types.

Hair bundle structure is a major determinant of bundle mechanics and thus of a hair cell's ability to encode sound and head movement stimuli. Little quantitative information about bundle structure is available for vestibular organs. Here we characterize hair bundle heights in the utricle of a turtle, Trachemys scripta. We visualized bundles from the side using confocal images of utricular slices. We measured kinocilia and stereocilia heights and array length (distance from tall to short end of bundle), and we calculated a KS ratio (kinocilium height/height of the tallest stereocilia) and bundle slope (height fall-off from tall to short end of bundle). To ensure that our measurements reflect in vivo dimensions as closely as possible, we used fixed but undehydrated utricular slices, and we measured heights in three dimensions by tracing kinocilia and stereocilia through adjacent confocal sections. Bundle heights vary significantly with position on the utricular macula and with hair cell type. Type II hair cells are found throughout the macula. We identified four subgroups that differ in bundle structure: zone 1 (lateral extrastriola), striolar zone 2, striolar zone 3, and zone 4 (medial extrastriola). Type I hair cells are confined to striolar zone 3. They have taller stereocilia, longer arrays, lower KS ratios, and steeper slopes than do neighboring (zone 3) type II bundles. Models and experiments suggest that these location- and type-specific differences in bundle heights will yield parallel variations in bundle mechanics. Our data also raise the possibility that differences in bundle structure and mechanics will help explain location- and type-specific differences in the physiological profiles of utricular afferents, which have been reported in frogs and mammals.

Acoustic Maculae↗
PubMed2003

Time course and extent of mechanotransducer adaptation in mouse utricular hair cells: comparison with frog saccular hair cells.

Whole cell transduction currents were recorded from hair cells in early postnatal mouse utricles in response to step deflections of the hair bundle. For displacement steps delivered by a stiff probe (1-ms rise time), half-maximal responses decayed monoexponentially with a mean time constant of 30 ms. Adaptation and other transduction properties did not vary systematically with hair cell type (I vs. II) or region (striola vs. extrastriola). Thus regional variation in the phasic properties of utricular afferents arises through other mechanisms. When bundles were deflected by a fluid jet, which delivers force steps, transduction currents decayed about 3-fold more slowly than during displacement steps. A simple model of myosin-mediated adaptation predicts such slowing through forward creep of the bundle during a force step. For a faster stiff probe (rise time 200 micros), step responses of both mouse utricular and frog saccular hair cells decayed with two exponential components, which may correspond to distinct feedback processes. For half-maximal responses, the two components had mean time constants of 5 and 45 ms (mouse) and 2 and 18 ms (frog). The fast and slow components dominated the decay of responses to small and large stimuli, respectively. Adaptation shifts the instantaneous operating range in the direction of the adapting step. In frog saccular hair cells, the operating range shift is a constant percentage of the displacement. In mouse utricular hair cells, the percentage shift increases for large displacements, extending the range of background stimuli over which adaptation can restore instantaneous sensitivity.

Adaptation, Physiological↗
PubMed2006

Creeping hair: an isolated hair burrowing in the uppermost dermis resembling larva migrans.

A 55-year-old Japanese male presented with a slowly moving linear erythema that looked like an eruption of creeping disease, or cutaneous larva migrans. The eruption extended linearly along Langer's line of the lateral side of the abdomen to the lower back, leaving wave-like erythema. In the top third of the erythematous eruption, close examination demonstrated a black thin line, which was revealed to be a hair shaft by a shallow incision of the skin. After removal of the hair, the eruption diminished immediately, leaving a slight pigmentation. An ingrown pubic hair seemed to have migrated with the lower end forward along Langer's line, because of the arrangement of hair cuticle and the force of body motion. Linearly moving erythematous eruptions that look like that of larva migrans should be differentiated from creeping hair by close examination detecting burrowing hair.

Diagnosis, Differential↗
PubMed2004

Transient activation of beta-catenin signalling in adult mouse epidermis is sufficient to induce new hair follicles but continuous activation is required to maintain hair follicle tumours.

When beta-catenin signalling is disturbed from mid-gestation onwards lineage commitment is profoundly altered in postnatal mouse epidermis. We have investigated whether adult epidermis has the capacity for beta-catenin-induced lineage conversion without prior embryonic priming. We fused N-terminally truncated, stabilised beta-catenin to the ligand-binding domain of a mutant oestrogen receptor (DeltaNbeta-cateninER). DeltaNbeta-cateninER was expressed in the epidermis of transgenic mice under the control of the keratin 14 promoter and beta-catenin activity was induced in adult epidermis by topical application of 4-hydroxytamoxifen (4OHT). Within 7 days of daily 4OHT treatment resting hair follicles were recruited into the hair growth cycle and epithelial outgrowths formed from existing hair follicles and from interfollicular epidermis. The outgrowths expressed Sonic hedgehog, Patched and markers of hair follicle differentiation, indicative of de novo follicle formation. The interfollicular epidermal differentiation program was largely unaffected but after an initial wave of sebaceous gland duplication sebocyte differentiation was inhibited. A single application of 4OHT was as effective as repeated doses in inducing new follicles and growth of existing follicles. Treatment of epidermis with 4OHT for 21 days resulted in conversion of hair follicles to benign tumours resembling trichofolliculomas. The tumours were dependent on continuous activation of beta-catenin and by 28 days after removal of the drug they had largely regressed. We conclude that interfollicular epidermis and sebaceous glands retain the ability to be reprogrammed in adult life and that continuous beta-catenin signalling is required to maintain hair follicle tumours.

Animals↗
PubMed1997

Semi-quantitative measurements of body hair in hirsute women compare well with direct diameter measurements of hair shafts.

No standards exist for the evaluation of hair in hirsute women. This study compared the semi-quantitative visual scoring of body hair, using the Ferriman & Gallwey scale, in 88 hirsute women with direct objective measurements of hair shaft diameter and daily linear growth rates of hair growing on the pre-auricular area of the face, the forearm, the anterior abdominal wall and the anterior thigh. There was a significant correlation between the semi-quantitative score and diameter measurements on the forearm, abdominal wall and thigh. There was no relationship between linear growth rates at any of the four sites and the semi-quantitative score. The conclusion of this report is that suitably standardised and controlled semi-quantitative measurement of hair in hirsute women with visual analogue scores would appear to offer information similar to that obtained by direct measurement of hair diameter.

Adolescent↗
PubMed2006

Human scalp hair follicles are both a target and a source of prolactin, which serves as an autocrine and/or paracrine promoter of apoptosis-driven hair follicle regression.

The prototypic pituitary hormone prolactin (PRL) exerts a wide variety of bioregulatory effects in mammals and is also found in extrapituitary sites, including murine skin. Here, we show by reverse transcriptase-polymerase chain reaction and immunohistology that, contrary to a previous report, human skin and normal human scalp hair follicles (HFs), in particular, express both PRL and PRL receptors (PRL-R) at the mRNA and protein level. PRL and PRL-R immunoreactivity can be detected in the epithelium of human anagen VI HFs, while the HF mesenchyme is negative. During the HF transformation from growth (anagen) to apoptosis-driven regression (catagen), PRL and PRL-R immunoreactivity appear up-regulated. Treatment of organ-cultured human scalp HFs with high-dose PRL (400 ng/ml) results in a significant inhibition of hair shaft elongation and premature catagen development, along with reduced proliferation and increased apoptosis of hair bulb keratinocytes (Ki-67/terminal dUTP nick-end labeling immunohistomorphometry). This shows that PRL receptors, expressed in HFs, are functional and that human skin and human scalp HFs are both direct targets and sources of PRL. Our data suggest that PRL acts as an autocrine hair growth modulator with catagen-promoting functions and that the hair growth-inhibitory effects of PRL demonstrated here may underlie the as yet ill-understood hair loss in patients with hyper-prolactinemia.

Apoptosis↗
PubMed1992

Differences in hair bundles associated with type I and type II vestibular hair cells of the guinea pig saccule.

Several studies have reported variations in shape and size of stereociliary bundles and in a limited number of observations have associated them to type I and type II hair cells. A systematic study has been undertaken for which a technique was developed in order to identify both cell types and their corresponding hair bundles. Numerous fissures were obtained in saccular epithelia and observed in scanning electron microscopy. Saccular type I and type II hair cells in the guinea pig were found to have distinctive hair bundles. The tallest stereocilia of almost all type I cells were longer than 6 microns, and were shorter in the striola compared to the periphery. In contrast, the tallest stereocilia of almost all type II cells were shorter than 6 microns and were not found to vary notably in size from the striola to the periphery. Hair bundles with stereocilia organized in straight or in staggered rows were found for both types of cells across the whole saccular epithelium, with no apparent particular distribution. Possible physiological significance of differences in hair bundles is discussed.

Animals↗
PubMed1981

Analyses of cystine in human hair: its level in women's hair of former times.

An appropriate procedure for analysis of cystine in the hair has been established, and this procedure was applied to the hair of Japanese women. The recovery of authentic cystine added to a hair sample was 85-90% in 6N HCl hydrolysis, and 96% in acid hydrolysis after performic acid oxidation. The 18-hr acid hydrolysis, but not 4-hr one, was sufficient to digest the hair. In colorimetry by using phosphotungstate, Brown's reagent gave a stable color development. The cystine content by amino acid autoanalysis was significantly correlated with that by the phosphotungstate colorimetry by the modified method of Kassel et al. or of Shinohara. The cystine content in women's hair, which was collected from specimens of different individuals cut during the period from 1910s to 1980, indicated a wide variation ranging from 0.654 to 1.607 mmol half-cystine per g of hair after washing with 0.5% sodium laurylsulfate.

Adult↗
PubMedDate not supplied

Secondary ion mass spectrometric investigation of penetration of coconut and mineral oils into human hair fibers: relevance to hair damage.

An attempt has been made to show the difference in the penetrability of coconut oil and mineral oil in human hair. We have used secondary ion mass spectrometry (SIMS) in combination with a time-of-flight (TOF) mass spectrometer. Characteristic ions formed by the pure components when bombarded with gallium ions have been identified with their m/z values. The distribution of the ion, characteristic of the particular treatment, has been established in the cross sections of hair treated with coconut and mineral oils. The results show that coconut oil penetrates the hair shaft while mineral oil does not. The difference may be due to the polarity of the coconut oil compared to the nonpolar nature of the mineral oil. The affinity of the penetrant to the protein seems to be the cause for this difference in their behavior. This study also indicates that the swelling of hair is limited by the presence oil. Since the process of swelling and deswelling of hair is one of the causes of hair damage by hygral fatigue, coconut oil, which is a better penetrant than mineral oil, may provide better protection from damage by hygral fatigue.

Coconut Oil↗
PubMedDate not supplied

Scalp hair length. II. Estimating the percentages of adults in the USA and larger populations by hair length.

Scalp hair length assessments by anatomical site, previously made in Florida theme parks on adults, are related to anatomical measurements to obtain estimates of free-hanging hair lengths in centimeters. A plot of the natural logarithm of the percent population versus these hair lengths provides a straight line and an equation that permits the estimation of the numbers of persons in the USA and larger populations with hair lengths up to 183 cm (just beyond ankle-length). Data were also collected via a literature search for even longer hair lengths (ankle-length or longer) to provide an equation to estimate the numbers of persons with exceptionally long hair. A comparative plot of these two equations suggests that "normal" anagen periods may be considerably longer than current estimates in the literature.

Adolescent↗
PubMedDate not supplied

Study of the interaction between hair protein and organic acid that improves hair-set durability by near-infrared spectroscopy.

In this study, hydrogen bonds around hair proteins were analyzed by near-infrared spectroscopy to reveal the mechanism of improving hair-set durability by treatment with a specific organic acid. The improvement of set durability was confirmed by measurement on single hair fibers, suggesting that improvement is not because of the surface adhesion increase but because of the internal changes in the hair. Through analysis by two-dimensional near-infrared correlation spectroscopy, it was found that a combination band of stretching NH and amide II is deconvoluted into three bands interacting with different hydrogen bonds. From the assignment of the three bands, the behavior of the organic acid in the hair was clarified as follows: it absorbs at the site where water originally binds, even in extremely dry conditions, prevents water penetration, and makes strong and stable hydrogen bonds with hair proteins. The formation of such strong and stable hydrogen bonds suppresses the exchange of hydrogen bonds that is the cause of the breakage of set durability.

Hair↗
PubMed1981

Outer root sheath keratinization in anagen and catagen of the mammalian hair follicle. A seventh distinct type of keratinization in the hair follicle: trichilemmal keratinization.

Trichilemmal keratinization, first described in Maurer in 1895 and rediscovered by Holmes (1968) and Pinkus (1968) converts the stratified epithelium of the outer root sheath into anuclear keratin without an intervening keratohyalin layer. It is a distinct seventh type of keratinization in the hair follicle, not derived from the hair matrix. It occurs wherever outer root sheath is not apposed to inner root sheath, in anagen in the zone of sloughing just below the opening of the sebaceous duct, in catagen in the trichilemmal sac surrounding the lower end of the dying hair shaft where it forms the club of the telogen hair. Electron microscopic study of the thick hairs of dogs (but not the tiny hairs of rodents) reveals intricate infoldings of non-keratinized and keratinized cells. It also shows unique ladder-like membrane coating granules in anagen, which are strongly acid phosphatase-positive and are suggested to be the source of enzyme involved with disintegration of the inner root sheath.

Acid Phosphatase↗
PubMed1998

Pesticide deposition in hair: preliminary results of a model study of methomyl incorporation into rabbit hair.

This work studied the incorporation of methomyl, a carbamate insecticide, into the hair of New Zealand white rabbits. A total of 600 mg methomyl was administered by drinking water over 4 mo, and acetylcholinesterase activity in serum was monitored. At the end of the dosing period, hair from the back of the rabbits was cut off, and the methomyl concentration was measured using ELISA and HPLC. A decrease of serum acetylcholinesterase occurred. The top cm of hair contained no methomyl, the second cm contained 0.9 ng/mg and the 3rd cm of hair contained 3 ng methomyl/mg. Methomyl was incorporated into the rabbit hair in a process independent of gender but dependent on the hair growth rate.

Acetylcholinesterase↗
PubMed2002

Statistical evaluation of morphological data of Japanese head hair and the screening of evidential hair samples by cluster analysis.

Intra-individual and inter-individual variations in Japanese head hair morphology were reevaluated and the screening of evidential hair samples using a statistical method was investigated. A quantification of the morphological data was used as a system in which morphological features obtained by macroscopic and microscopic observations can be objectively processed in the form of numerical information. For confirming the availability of morphological features for hair comparison, the inter-individual comparison of ten male Japanese was investigated by discrimination analysis using 18 variables including five original numerical morphological features (variables) and 13 variables obtained from six morphological features by quantification. The majority of the comparisons showed a high level of discrimination between two individuals. For morphologically narrowing down the number of evidential hair samples collected from a crime scene, a screening method was investigated by cluster analysis using 18 variables. In an experimental model of evidential hair samples derived from 20 individuals, hair samples from 13 individuals were successfully discriminated using the cluster analysis described in the present investigation.

Journal Article↗
PubMed2005

Nod factors alter the microtubule cytoskeleton in Medicago truncatula root hairs to allow root hair reorientation.

The microtubule (MT) cytoskeleton is an important part of the tip-growth machinery in legume root hairs. Here we report the effect of Nod factor (NF) on MTs in root hairs of Medicago truncatula. In tip-growing hairs, the ones that typically curl around rhizobia, NF caused a subtle shortening of the endoplasmic MT array, which recovered within 10 min, whereas cortical MTs were not visibly affected. In growth-arresting root hairs, endoplasmic MTs disappeared shortly after NF application, but reformed within 20 min, whereas cortical MTs remained present in a high density. After NF treatment, growth-arresting hairs were swelling at their tips, after which a new outgrowth formed that deviated with a certain angle from the former growth axis. MT depolymerization with oryzalin caused a growth deviation similar to the NF; whereas, combined with NF, oryzalin increased and the MT-stabilizing drug taxol suppressed NF-induced growth deviation. The NF-induced disappearance of the endoplasmic MTs correlated with a loss of polar cytoarchitecture and straight growth directionality, whereas the reappearance of endoplasmic MTs correlated with the new set up of polar cytoarchitecture. Drug studies showed that MTs are involved in determining root hair elongation in a new direction after NF treatment.

Cytoskeleton↗
PubMed2004

Circumscribed scalp hair loss following multiple hair-cutter ant invasion.

A 32-year-old woman presented with an abrupt, localized loss of scalp hair that occurred on the previous day. Her nails, skin, and mucosae were normal. On the vertex of the scalp, there was a circular patch of alopecia; the hairs were broken at approximately equal lengths above the skin surface. Several erythematous macules were seen in the affected area, but scale, twisted hair, and exclamation-mark hairs were not present. Further examination revealed the presence of ants on the scalp. This patient is one of several referred to our department presenting with hair loss associated with hair-cutter ant invasion.

Adult↗