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At least 217 records · Page 12Linked to original sources
PubMed2001

Contrasting localization of c-Myc with other Myc superfamily transcription factors in the human hair follicle and during the hair growth cycle.

The mammalian hair follicle is a highly dynamic skin appendage that undergoes repeated cycles of growth and regression, involving closely co-ordinated regulation of cell proliferation, differentiation, and apoptosis. The Myc superfamily of transcription factors have been strongly implicated in the regulation of these processes in many tissues. Using immunohistochemistry, we have investigated the patterns of c-Myc, N-Myc, Max, and Mad1-4 expression at different stages of the human hair growth cycle. N-Myc, Max, Mad1, and Mad3 immunoreactivity was detected in the epidermis and the epithelium of both anagen and telogen hair follicles. Three distinct patterns of hair follicle c-Myc immunoreactivity were observed. In the infundibulum, c-Myc staining was predominantly in the basal layers, with little detectable immunoreactivity in the terminally differentiating suprabasal layers; this pattern was similar to that seen in the epidermis. In contrast, c-Myc expression in the follicle bulb was found both in the proliferating germinative epithelial cells and in the terminally differentiating matrix cells that give rise to the hair fiber. Finally, intense c-Myc immunoreactivity was detected in the bulge region of the outer root sheath. Using the C8/144B antibody as a bulge marker, we confirmed that c-Myc immunoreactivity in the outer root sheath correlates with the putative hair follicle stem cell compartment. c-Myc expression in the bulge was independent of the hair growth cycle stage. Our data suggest that Myc superfamily members serve different functions in separate epithelial compartments of the hair follicle and may play an important role in determining cell fate within the putative stem cell compartment.

Basic Helix-Loop-Helix Leucine Zipper Transcriptio↗
PubMed2002

High efficiency genetic modification of hair follicles and growing hair shafts.

A technique for genetic modification of hair follicles was developed which results in efficient alteration of the hair shaft phenotype. High-level in vivo transgene expression was maintained in hair follicles such that growing hair shafts were phenotypically altered. Mouse anagen skin fragments, maintained in histoculture, were genetically modified at high efficiency with adenoviral-GFP. The histocultured skin fragments were treated with collagenase which made hair follicles accessible to the adenoviral GFP gene, allowing high-efficiency transduction. These skin fragments were subsequently grafted on to nude mice where GFP was readily visualized in as many as 75% of hair follicles. Most follicles produced GFP-fluorescent growing hair shafts. This technique has produced efficient genetic modification of the hair shaft.

Adenoviridae↗
PubMed1996

Consecutive wide and long single hair-bearing transposition flaps in combination with hair transplantation for the management of slot formation after alopecia reducing surgery.

BACKGROUND: Because the Frechet-style triple hair-bearing transposition flaps use up a great deal of scalp laxity from both occipitoparietal areas, it is virtually impossible to perform simultaneous donor harvesting for hair transplantation. The flaps in this technique are also prone to tip necroses due to their narrow width and pointed tips. This article presents a sequential protocol that dramatically and easily treats the slot, while simultaneously allowing hair transplantation to be performed to the frontal area. OBJECTIVE: To present a simple method that combines hair transplantation with consecutive wide and long single hair-bearing transposition flaps for the management of slot formation after alopecia reducing surgery. METHOD: A wide and long single hair-bearing transposition flap is first performed. The area directly inferior and contralateral to the side from where the superior flap is transposed is then used for donor harvesting. This method is repeated with each progressive hair grafting session until the desired result is accomplished. RESULTS: In the over 100 cases performed by the author to date, the results have been consistently excellent with complications nonexistent thus far. CONCLUSION: Using consecutive wide and long single hair-bearing transposition flaps is a safer, more aesthetically pleasing, and easier way to manage slot formation when compared with the triple flap technique. Besides these advantages, it affords the surgeon the opportunity to work on the frontal hairline immediately after the flap procedure is performed.

Alopecia↗
PubMedDate not supplied

A girl with loose anagen hair syndrome and uncombable, spun-glass hair.

A 4-year-old girl presented with a 2-year history of scalp hair that had an odd texture, was difficult to manage, tended to "stick out" from the scalp, and was irregular in length. A hair pull test revealed that hairs could be easily and painlessly extracted. Light microscopic examination of the hair demonstrated anagen hairs with a ruffled cuticle and distorted bulb as well as an unusual undulation and grooving of the shafts. These findings are consistent with both loose anagen and uncombable hair syndromes. The occurrence of both syndromes in the same patient seems unlikely, and we propose that our patient has loose anagen hair syndrome with features resembling uncombable hair syndrome.

Child, Preschool↗
PubMed1998

Immunolocalization of myosin Ibeta in the hair cell's hair bundle.

The hair bundle, the hair cell's sensory organelle, transduces acoustical or vestibular stimulation into a change in membrane potential. The actin-based stereociliary processes of the hair bundle contain a number of myosin isoforms that may be important to the bundle's function. One of these isoforms, myosin Ibeta, has been proposed to constitute an adaptation motor controlling sensitivity of the hair bundle to mechanical displacement. To gain insight into myosin Ibeta's function, its distribution within the hair bundle was examined. A polyclonal antibody was produced that recognizes a protein surface loop within the head domain of myosin Ibeta. This antibody was used to localize myosin Ibeta in the hair cell by indirect-immunofluorescence microscopy and indirect-immunoelectron microscopy. Within the hair bundle, myosin Ibeta immunoreactivity was located along the sides of the stereociliary actin core, concentrated in the distal two-thirds of the stereocilia. Within the hair cell soma, myosin Ibeta immunoreactivity was located throughout the cytoplasm exclusive of the cuticular plate.

Amino Acid Sequence↗
PubMed2004

Cyclosporin A-induced hair growth in mice is associated with inhibition of hair follicle regression.

BACKGROUND: Cyclosporin A (CsA) often causes hair growth in transplant recipients. Our objectives were to evaluate the effect of CsA on follicular hair keratinocyte growth in nude mice by assessing their proliferation in vivo, and to assess the ability of CsA to prevent follicular keratinocyte apoptosis in vivo and chemotherapy-induced keratinocyte apoptosis in vitro. METHODS: Nude mice were fed various daily doses of CsA (10-100 mg/kg). Dorsal skin sections stained with hematoxylin and eosin, followed by immunostaining with 4-deoxybromouridine, were examined for determination of hair follicle number and hair follicle keratinocyte proliferation. Follicular keratinocytes were isolated and examined for apoptotic status. Apoptosis was induced in vitro in a keratinocyte cell line by 4-hydroperoxycyclophosphamide. The antiapoptotic effects of various CsA concentrations (0.1-5 microg/ml) were measured by annexin-V/propidium iodide binding. RESULTS: CsA caused a dose-dependent increase in the number of hair follicles but had no effect on follicular keratinocyte proliferation. Treatment with CsA decreased the number of apoptotic follicular keratinocytes. In vitro, there was a dose-dependent inhibition of the extent of early and late apoptosis of treated keratinocytes. CONCLUSION: CsA may induce hair growth by increasing the number of hair follicles and inhibiting apoptosis of follicular keratinocytes, thereby delaying hair follicle regression.

Animals↗
PubMed2005

The HOXC13-controlled expression of early hair keratin genes in the human hair follicle does not involve TALE proteins MEIS and PREP as cofactors.

We previously showed that the homeodomain protein HOXC13 is involved in the expression control of the early human hair keratin genes hHa5 and hHa2, which contain specific HOXC13 binding sites in their proximal promoters. Hox specificity is generally thought to be enhanced by the interaction with members of the TALE superclass of homeodomain proteins Pbx, Meis, and Prep. Using reverse transcription PCR with total human hair follicle RNA, we demonstrated transcripts of the major TALE proteins PBX1-4, MEIS1, 2 and PREP1, 2 in the human hair follicle. In view of the presence of MEIS/PREP responsive elements in close vicinity to the HOXC13 binding sites of the hHa5 and hHa2 promoters, we determined the expression sites of these TALE proteins in the human hair follicle. We found that MEIS1, MEIS2, PREP1 and PREP2 were differentially expressed in the three layers of the inner root sheath. In addition, MEIS2 and PREP1 exhibited expression in the mid-to upper hair cortex, with PREP1 being also expressed in the dermal papilla and the connective tissue sheath of the hair follicle. In virtually all cases, the expression of these TALE proteins was exclusively cytoplasmic. Considering that in contrast, HOXC13 is expressed in the nuclei of matrix, precortex and lower cuticle cells of the hair follicle, our data suggest that despite the presence of MEIS/PREP binding sites in the hHa5 and hHa2 promoters, the HOXC13-controlled activation of these genes in the hair follicle does not seem to involve these TALE proteins as cofactors.

Cell Nucleus↗
PubMed1985

Incorporation routes of elements into human hair; implications for hair analysis used for monitoring.

A study has been made on the incorporation of some trace elements and minerals into human hair by measuring their distributions across hair diameters. For this study the Particle Induced X-ray Emission (PIXE) technique using the proton microbeam of the Vrije Universiteit of Amsterdam has been applied. Results of measurements on single hair strands at different positions in the root and outside the skin provide evidence that the elements not only can enter the cortex via the matrix but also via the hair root sheaths. Moreover, there are indications that the distribution of an endogenous element is not always homogeneously spread over a cross section of the hair. Endogenous Fe and Pb seem to be peaked on the periphery of the hair by natural means, while the elements S,Zn and Cu of the samples measured are found to be distributed homogeneously across the hair diameter. The consequences for hair analysis in use for monitoring the trace elements status of an individual are discussed.

Adult↗
PubMed1987

The distribution of hair cell bundle lengths and orientations suggests an unexpected pattern of hair cell stimulation in the chick cochlea.

A detailed analysis of the morphological polarity of the hair cell bundles on the chick cochlea was carried out. Although the pattern is identical from cochlea to cochlea, the morphological polarity of the bundles varies at different positions on the cochlea. More specifically, the hair cell bundles located immediately adjacent to the inferior and superior edges are oriented with their morphological polarity perpendicular to the margins. As we move across the cochlea (transect it), there is a gradual rotation in the polarity of the bundles so that in the center of the cochlea the hair cells are oriented at an angle to those at the edges. As we continue to the superior edge the polarity gradually rotates back again. The amount of rotation depends on the position of the transect such that at the extreme proximal end there is little rotation, while at the distal end the rotation is up to 90 degrees. The rotation is always in the same direction with the tallest rows of stereocilia nearest the distal end of the cochlea. Measurements of the length of the longest stereocilia in the hair cell bundles revealed that not only are the bundles systematically longer from the proximal to distal end of the cochlea, but also the hair cells on the superior edge are significantly longer than those on the inferior edge at the same distance from one end of the cochlea. If we draw on micrographs of the cochlea contour lines through hair cells whose stereocilia are the same height, these lines coincide with the morphological polarity of the hair cells included in these contours. Furthermore analysis of damage to the cochlea induced by pure tones of high intensity also roughly follows the same contour lines. We conclude that unlike what has been thought, the stimulation of hair cells by pure tones may not occur in a strictly transverse pattern, but instead may follow the oblique contours demonstrated here.

Acoustic Stimulation↗
PubMed1989

The responses of cochlear hair cells to tonic displacements of the sensory hair bundle.

Hair bundle displacements and receptor potentials were recorded from outer hair cells (OHCs) in organotypic cultures of the mouse cochlea during force steps applied to the bundles with a silica probe of known stiffness. The receptor potentials of some OHCs adapt for excitatory displacements and the time constants of receptor potential adaptation and hair bundle force relaxation for excitatory displacements are very similar. Thus in these OHCs, the receptor potentials correspond to the applied force for excitatory displacements. For inhibitory displacements, the receptor potentials correspond to hair bundle displacement. Some OHC receptor potentials are nonadapting and follow displacement in both the excitatory and inhibitory directions. The hair bundles of nonadapting OHCs are less stiff than those of adapting OHCs and nonadapting OHCs are an order of magnitude less sensitive to hair bundle displacement than adapting OHCs. In response to a combination of excitatory, tonic, hair bundle displacement and current injection, the receptor potentials of nonadapting OHCs decline as the membrane potential is made more positive and reverse near 0 mV. When the receptor potentials of adapting OHCs measured during current injection are compensated for constant input resistance and driving voltage across the transducer conductance, the receptor potential amplitude at the offset of the step displacement is independent of the level and polarity of the injected current. Before adaptation, at the onset of the step displacement of the hair bundle, the amplitude of the receptor potential increases as the injected current becomes more positive. For adapting OHCs, the receptor potential amplitude is a linear function of excitatory bundle displacement for amplitudes less than 50 nm. With negative, but not positive, current injection the receptor potentials at the onset of the displacement tend to saturate and the slope of the function decreases. This voltage dependent control of OHC transducer operating range is proposed to have a role in regulating the sensitivity of the cochlea.

Adaptation, Physiological↗
PubMed1995

Theoretical limits of the evaluation of drug concentrations in hair due to irregular hair growth.

When examining concentration relationships of doses it must be taken into account that hair growth is irregular. Hair growing from the shaved skin after a single dose of a certain drug cannot possibly contain the same concentration as hair after the same dose that has not been cut over a long period. Concentrations can even change during the hair growth in cases where the hair had been cut a couple of months before the hair sample was taken. The variations in the expected concentrations can exceed 20%. On the other hand, the evaluation of a hair tuft which has grown after the last drug consumption may be important in forensic cases where the hair which has grown earlier is not available. This may lead to misinterpretations at low concentrations. Expected concentrations are calculated assuming a telogen part of 10%.

Hair↗
PubMed1987

The infected hairs of tinea capitis due to Microsporum canis: demonstration of uniqueness of the hair cuticle by scanning electron microscopy.

Scanning and transmission electron microscopic studies were done on scalp hairs of four patients infected with ectothrix Microsporum canis. Both freeze fracture and cross-sectioning of hairs revealed a thick sheath of fungal spores encircling the hair shaft beneath an intact cuticle. These spores were not visible on surface inspection but became apparent only where the cuticle had been rubbed off or broken. Daily selenium sulfide shampoos removed all of the spores from these sites. The cuticle is viewed as being an effective barrier to the penetration of fungi, so that the hair is vulnerable to fungus infection only deep within the hair follicle below the level of the mature cuticle. Once the fungus enters the hair cortex just above the hair bulb, it produces myriads of spores that remain trapped and hidden beneath the cuticle for the length of the intact hair.

Child↗
PubMed2000

Differentiation of hair growth cycle from scalp hair roots for the diagnosis of glucose-6-phosphate dehydrogenase deficiency in neonates.

Hair analysis can be used as a screening tool in the diagnosis of genetic diseases. The scalp hair roots of 67 normal neonates and 39 neonates with glucose-6-phosphate dehydrogenase (G6PD) deficiency were analysed using Fourier transform infrared (FT-IR) microspectroscopy to differentiate the stages of the hair growth cycle and to diagnose the genetic disorder on the basis of spectral differences. We have demonstrated that FT-IR microspectroscopy is a rapid and effective noninvasive diagnostic method to differentiate scalp hair roots of normal neonates into the anagen, catagen or telogen phases of the hair growth cycle, using IR spectral differences within the 3000-2800 cm(-1) region and the IR peak area ratio of 2854 cm(-1)/2873 cm(-1) or 1084 cm(-1)/amide II band (p<0.001). Moreover, G6PD-deficient neonates could be accurately diagnosed from telogen phase hair roots owing to significant differences in IR peak area ratios of 2854 cm(-1)/2873(-1) or 1084 cm(-1)/amide II band compared to normal values in healthy neonates. The result suggests that the application of FT-IR microspectroscopy may be capable not only of differentiating the hair growth cycle into anagen, categen or telogen phases but also of detecting G6PD deficiency. Hair root analysis promises to be a useful complement to serum and urine analysis in the diagnosis of genetic diseases.

Female↗
PubMed2001

A comprehensive guide for the accurate classification of murine hair follicles in distinct hair cycle stages.

Numerous strains of mice with defined mutations display pronounced abnormalities of hair follicle cycling, even in the absence of overt alterations of the skin and hair phenotype; however, in order to recognize even subtle, hair cycle-related abnormalities, it is critically important to be able to determine accurately and classify the major stages of the normal murine hair cycle. In this comprehensive guide, we present pragmatic basic and auxiliary criteria for recognizing key stages of hair follicle growth (anagen), regression (catagen) and quiescence (telogen) in C57BL/6NCrlBR mice, which are largely based on previous work from other authors. For each stage, a schematic drawing and representative micrographs are provided in order to illustrate these criteria. The basic criteria can be employed for all mouse strains and require only routine histochemical techniques. The auxiliary criteria depend on the immunohistochemical analysis of three markers (interleukin-1 receptor type I, transforming growth factor-beta receptor type II, and neural cell-adhesion molecule), which allow a refined analysis of anatomical hair follicle compartments during all hair cycle stages. In contrast to prior staging systems, we suggest dividing anagen III into three distinct substages, based on morphologic differences, onset and progression of melanogenesis, and the position of the dermal papilla in the subcutis. The computer-generated schematic representations of each stage are presented with the aim of standardizing reports on follicular gene and protein expression patterns. This guide should become a useful tool when screening new mouse mutants or mice treated with pharmaceuticals for discrete morphologic abnormalities of hair follicle cycling in a highly reproducible, easily applicable, and quantifiable manner.

Animals↗
PubMed2002

Syndecan-1 is strongly expressed in the anagen hair follicle outer root sheath and in the dermal papilla but expression diminishes with involution of the hair follicle.

Syndecan-1 is the prototypic member of a family of heparan sulfate-bearing cell surface proteoglycans that function in adhesion, cell-extracellular matrix interactions, migration, and proliferation. During embryogenesis, syndecan-1 expression in the epithelium is downregulated when the epithelium gives rise to motile mesenchymal cells, whereas mesenchymal syndecan-1 expression is upregulated during organ formation. In aggressive basal cell carcinomas, syndecan-1 expression is evident in the stroma. Some neoplastic cells induce stroma to meet needs for growth, and it may be the mesenchymal cells that produce and shed syndecan-1 into the stroma. The physiologic mechanism by which the hair follicle undergoes its cyclic process of involution and formation of a new active hair follicle is not well understood. Sixty scalp biopsies and a large scalp resection were evaluated for syndecan-1 expression within hair follicles in the growing (anagen), involuting (catagen), and resting (telogen) phases. Strong syndecan-1 immunoreactivity was evident in the outer root sheath (ORS) of the anagen hair follicle, but this expression diminished in intensity with the involution and resting stages in the hair follicle cycle. The diminution of syndecan-1 immunoreactivity in the ORS of involuting and resting hair follicles may be a result of terminal keratinocyte differentiation. Syndecan-1 was also present in the dermal papilla of the anagen hair follicle, where it may promote growth factor-mediated cell signaling that induces and maintains growth of the hair shaft and the inner root sheath.

Dermis↗
PubMed1996

Evidence for saturable incorporation of methadone into rat hair: relationships among oral dose, plasma concentration, and hair content.

Six groups of six male Wistar rats were administered methadone in their drinking water over the concentration range 0-0.25 mg/ml. Hair and trunk blood samples were collected after a 6-week period of drug administration. Immunoreactive methadone was measured by radioimmunoassay and methadone and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidene (EDDP), by gas chromatography in plasma and alkali digests of hair. Plasma methadone concentration increased with increasing oral dose. The mean hair concentration of methadone increased to a maximum of 5.1 ng/mg at a drinking water concentration of 0.1 mg/ml corresponding to a plasma level of 14.0 ng/ml. No further significant rise in hair content was seen with higher drinking water concentrations despite a continuing increase in oral drug intake and in plasma methadone concentration. EDDP was not detected in plasma but was present at > 2 ng/mg in 25% of hair samples. The mean EDDP concentration in hair peaked at 3.2 ng/mg at the lowest dose level of methadone administered. The data suggest that methadone is incorporated into rat hair via a capacity-limited process that becomes saturated at plasma levels of some 14 ng/ml. Competition for uptake into hair between methadone and EDDP may occur.

Animals↗
PubMed2004

Macrophage-stimulating protein promotes hair growth ex vivo and induces anagen from telogen stage hair follicles in vivo.

Hepatocyte growth factor (HGF) is a promoter of hair follicle growth. We examined another HGF family member, macrophage-stimulating protein (MSP), for its hair follicle-modulating properties. Western blotting revealed presence of mature MSP in cultured human dermal papilla (DP) cells and bulbar dermal sheath (DS) cells, but not non-bulbar DS cells. Immunohistology demonstrated expression of MSP receptor RON in the outer and inner root sheaths, hair matrix cells, DP, and bulbar DS whereas non-follicular epithelium and some cells of the sweat glands exhibited low-level receptor expression. Human hair follicles exposed in vitro for 8 d to 0.1, 1, 10, and 100 ng per mL MSP all yielded a mean net increase in hair follicle length in excess of the mean baseline growth observed in controls. MSP was incubated with agarose beads and injected subcutaneously into mice all 70 d old when a uniform telogen state in dorsal skin was apparent. All eight mice receiving 1 microg MSP, and four of eight receiving 100 ng MSP showed induction of anagen hair growth at the site of bead implantation by 16 d whereas eight mice implanted with saline incubated beads had no hair growth. The data identify MSP as a modulator of hair growth.

Adult↗
PubMed1994

Vellus hair follicle-derived keratinocyte culture: a new experimental model in human hair research.

Biological and biochemical mechanisms of hair growth are difficult to study in vivo; therefore the development of in vitro models is of great interest. Today, we have of our disposal reliable techniques to cultivate cell populations and entire components of terminal hair follicles; however, in vitro culture models for cells derived from vellus hair follicles have not yet been established. In this study, we present a technique for cultivating vellus hair follicle-derived keratinocytes (VHK) and we present first findings on their characterization. Primary cultures of VHK were obtained as outgrowths of cultured intact vellus hair follicles prepared by microsurgical means after incubation of full-thickness human skin with dispase. (1) VHK cultures reached confluency after 16-20 days and 3-4 subcultures were possible. (2) VHK were characterized as epithelial cells by light and electron microscopy. (3) A multi-layered stratified epithelium with 8-10 cell layers was observed by electron microscopy presenting abundant keratinosomes in individual cells in contrast to outer root sheath keratinocytes. (4) Synthesis studies of two glycoproteins characteristic for undifferentiated (gp 38) and for differentiated (gp 80) keratinocytes revealed higher synthesis levels for gp 80 and lower levels for gp 38 in VHK as compared to normal epidermal keratinocytes in vitro. These findings suggest a distinct morphologic and differentiation pattern of VHK in culture. This experimental model provides a new tool to study mechanisms of hair growth regulation in vellus hair follicles and to compare them to those of terminal hair follicles.

Cell Differentiation↗