常见毛囊细胞角蛋白在毛囊周期中的表达研究

目的探讨常见毛囊细胞角蛋白在毛囊周期中的表达特征。 方法取毛囊发育期、生长期启动、生长期、退化期和静止期的小鼠皮肤,石蜡切片后通过免疫荧光的方法,检测细胞角蛋白Krt5、Krt6、Krt10、Krt14、Krt15和Krt19的表达情况。 结果Krt5在静止期和生长期启动表达于所有毛囊上皮细胞,在其他时期表达不一致;Krt6表达于所有时期的外根鞘细胞和内根鞘细胞;Krt10表达于生长期和退化期的毛母质和内根鞘细胞,在其他时期表达不一致;Krt14在生长期和退化期表达于所有毛囊上皮细胞,在其他时期表达不一致;Krt15和Krt19表达于毛囊发育期、生长期启动和静止期的毛囊隆突区细胞,在生长期和退化期表达不一致。 结论角蛋白作为毛囊结构或毛囊干细胞标记物仅适用于特定的毛囊周期。研究者在使用毛囊角蛋白作为标记物时,应首先明确其在毛囊周期中的表达情况。     

Evaluation of the permeability of hair growing ingredient encapsulated PLGA nanospheres to hair follicles and their hair growing effects

This paper describes the process of encapsulating hair growing ingredients in the PLGA nanospheres by emulsion solvent diffusion method and investigates the feasibility of using the PLGA nanospheres as the DDS (Drug delivery System) carriers for delivering various hair growing ingredients to hair follicles. In-vitro and in-vivo tests were conducted to verify the performances of encapsulated PLGA nanospheres with three different hair growing ingredients. In the in-vitro tests, the scalp-pore permeability of hair growing ingredient encapsulated PLGA nanospheres (dispersed in the PBS solution) was examined using human scalp biopsies in a modified Bronaugh diffusion chamber in comparison to that of the control samples containing the hair growing ingredient in the PBS solution. Furthermore, the hair growing effect of the encapsulated PLGA nanospheres was evaluated with the C3H mice in the in-vivo tests. By observing the fluorescence intensity of the ingredients, as shown in the cross-section photographs of the human scalp biopsies, it was found that the dispersion liquids containing hair growing ingredient encapsulated PLGA nanospheres exerted a scalp-pore permeability 2.0- to 2.5-fold more marked than that of the control samples. Also, the hair growing activities were enhanced by using the encapsulated PLGA nanospheres, which transformed the hair growth cycle from the resting phase to the growing phase. As a result, the degree of hair growth was improved significantly. These results suggested that the PLGA nanosphere can be a new DDS carrier for delivering hair growing ingredients and drugs to the hair follicles.     

Proteins of normal hair and of cysteine-deficient hair from mentally retarded siblings

1. S-Carboxymethylkerateines extracted from normal hair can be fractionated into high-sulphur and low-sulphur proteins similar to those obtained from sheep's wool. Normal human hair gives a major high-sulphur protein of higher molecular weight and S-carboxymethylcysteine content than any isolated from normal sheep's wool. 2. The proteins from cystine-deficient hair can also be divided into high-sulphur and low-sulphur proteins. There is a lower proportion of high-sulphur protein in cystine-deficient hair than in normal hair. 3. The high-sulphur proteins from cystine-deficient hair have an abnormal amino acid composition and in particular are lower in S-carboxymethylcysteine content than the corresponding proteins from normal hair. New components are present and the content of very high-sulphur proteins of high molecular weight is much decreased. The low-sulphur proteins of cystine-deficient hair are probably also deficient in S-carboxymethylcysteine. 4. The proteins of cystine-deficient hair probably resemble those in the normal hair root, except that disulphide-bridge formation has occurred.     

Sustained epithelial beta-catenin activity induces precocious hair development but disrupts hair follicle down-growth and hair shaft formation

During embryonic and postnatal development, Wnt/beta-catenin signaling is involved in several stages of hair morphogenesis from placode formation to hair shaft differentiation. Using a transgenic approach, we have investigated further the role of beta-catenin signaling in embryonic hair development. Forced epithelial stabilization of beta-catenin resulted in precocious and excessive induction of hair follicles even in the absence of Eda/Edar signaling, a pathway essential for primary hair placode formation. In addition, the spacing and size of the placodes was randomized. Surprisingly, the down-growth of follicles was suppressed and hair shaft production was severely impaired. Gene and reporter expression analyses revealed elevated mesenchymal Wnt activity, as well as increased BMP signaling, throughout the skin that was accompanied by upregulation of Sostdc1 (Wise, ectodin) expression. Our data suggest that BMPs are downstream of Wnt/beta-catenin and that their interplay may be a critical component in establishing correct patterning of hair follicles through the reaction-diffusion mechanism.     

Confocal microscopy of hair

Confocal microscopy is an excellent method for studying the localization of fluorescent stains. Used in this way, superior 3D images can be obtained from multiple optical sections with very shallow depth of field. The main advantage of this technique is that the sample is not damaged. We have taken serial confocal sections of hair and via specific image enhancement routines have obtained high-quality 3D images enabling the visualization of cuticle scale and its pattern of distribution. This has been done on various types of hair: bleached, permed and in certain pathological conditions. This first step will allow us to characterize the hair surface in terms of its roughness, and the distribution and form of cuticular scale, parameters that have potential in the assessment of dermocosmetic efficacy.     

Theoretical conditions for high-frequency hair bundle oscillations in auditory hair cells

Substantial evidence exists for spontaneous oscillations of hair cell stereociliary bundles in the lower vertebrate inner ear. Since the oscillations are larger than expected from Brownian motion, they must result from an active process in the stereociliary bundle suggested to underlie amplification of the sensory input as well as spontaneous otoacoustic emissions. However, their low frequency (<100 Hz) makes them unsuitable for amplification in birds and mammals that hear up to 5 kHz or higher. To examine the possibility of high-frequency oscillations, we used a finite-element model of the outer hair cell bundle incorporating previously measured mechanical parameters. Bundle motion was assumed to activate mechanotransducer channels according to the gating spring hypothesis, and the channels were regulated adaptively by Ca²⁺ binding. The model generated oscillations of freestanding bundles at 4 kHz whose sharpness of tuning depended on the mechanotransducer channel number and location, and the Ca²⁺ concentration. Entrainment of the oscillations by external stimuli was used to demonstrate nonlinear amplification. The oscillation frequency depended on channel parameters and was increased to 23 kHz principally by accelerating Ca²⁺ binding kinetics. Spontaneous oscillations persisted, becoming very narrow-band, when the hair bundle was loaded with a tectorial membrane mass.     

The actions of calcium on hair bundle mechanics in mammalian cochlear hair cells

Sound stimuli excite cochlear hair cells by vibration of each hair bundle, which opens mechanotransducer (MT) channels. We have measured hair-bundle mechanics in isolated rat cochleas by stimulation with flexible glass fibers and simultaneous recording of the MT current. Both inner and outer hair-cell bundles exhibited force-displacement relationships with a nonlinearity that reflects a time-dependent reduction in stiffness. The nonlinearity was abolished, and hair-bundle stiffness increased, by maneuvers that diminished calcium influx through the MT channels: lowering extracellular calcium, blocking the MT current with dihydrostreptomycin, or depolarizing to positive potentials. To simulate the effects of Ca²⁺, we constructed a finite-element model of the outer hair cell bundle that incorporates the gating-spring hypothesis for MT channel activation. Four calcium ions were assumed to bind to the MT channel, making it harder to open, and, in addition, Ca²⁺ was posited to cause either a channel release or a decrease in the gating-spring stiffness. Both mechanisms produced Ca²⁺ effects on adaptation and bundle mechanics comparable to those measured experimentally. We suggest that fast adaptation and force generation by the hair bundle may stem from the action of Ca²⁺ on the channel complex and do not necessarily require the direct involvement of a myosin motor. The significance of these results for cochlear transduction and amplification are discussed.     

Effects of Wnt-10b on hair shaft growth in hair follicle cultures

Wnts are deeply involved in the proliferation and differentiation of skin epithelial cells. We previously reported the differentiation of cultured primary skin epithelial cells toward hair shaft and inner root sheath (IRS) of the hair follicle via beta-catenin stabilization caused by Wnt-10b, however, the effects of Wnt-10b on cultured hair follicles have not been reported. In the present study, we examined the effects of Wnt-10b on shaft growth using organ cultures of whisker hair follicles in serum-free conditions. No hair shaft growth was observed in the absence of Wnt-10b, whereas its addition to the culture promoted elongation of the hair shaft, intensive incorporation of BrdU in matrix cells flanking the dermal papilla (DP), and beta-catenin stabilization in DP and IRS cells. These results suggest a promoting effect of Wnt-10b on hair shaft growth that is involved with stimulation of the DP via Wnt-10b/beta-catenin signalling, proliferation of matrix cells next to the DP, and differentiation of IRS cells by Wnt-10b.     

Validity of hair mineral testing

The variance of testing was compared between the College of American Pathologists clinical survey and that of a recent review about hair mineral testing. The review suggested that the accuracy of hair mineral testing was unreliable. In general, there was a greater range of variance in the College of American Pathologists testing results. These latter results are based on laboratory testing and are used as a “yardstick” to determine if a laboratory passes or fails that analyte and are considered a “gold standard.” An extract, which resulted from a method that avoided the washing step, was compared among five laboratories. Very good precision resulted, indicating that the varied washing steps used by the laboratories in a recent review were probably the source of much variance. Analysis of hair analysis seemed to yield important information in several historical or forensic cases involving Ludwig von Beethoven, Napoleon Bonaparte, ex-US-presidents Zachary Taylor and Andrew Jackson, and Charles Hall, an Arctic explorer. Several elements that were reviewed, including arsenic, cadmium, cobalt, germanium, lead, lithium, manganese, mercury, nickel, and thallium, showed relationships between body burden, dosage, and exposure or toxicity. Evidence of toxicity could not be found by measuring hair aluminum or vanadium. Chromium, selenium, and zinc seemed to have nutritional value. Ratios of hair elements with clinical importance could not be found.