Pili bigemini and terminal hair growth induced by low-fluence alexandrite laser hair removal

BACKGROUND: Different types of lasers are used in the removal of undesirable hair by targeting the hair follicles, with the melanin pigment acting as the chromophore, and through the mechanism of selective photothermolysis. OBJECTIVES: This report documents an unusual increase in terminal hair growth after alexandrite laser hair removal in three female patients. CONCLUSION: Excessive hair growth after alexandrite laser hair removal must be listed as one of the complications resulting from the use of a laser with a fluence that is too low and can possibly be prevented if we use higher energy to fully destroy the hair follicles, with consideration given to the skin type and an effective cooling system.     

Pemphigus and the terminal hair follicle

The scalp is frequently involved in the autoimmune skin disease pemphigus. This study demonstrates the distribution of pemphigus antigen in the scalp terminal hair follicle; as well as being found in the epidermis, it is distributed throughout the whole hair follicle outer root sheath and in the dermal bulb matrix cells. The increase in volume of target antigen offered by the follicular epithelium could be a factor determining scalp involvement in pemphigus.     

拉坦前列素对人头皮毛囊毛发生长的影响

目的:研究拉坦前列素对人头皮毛囊毛发生长状况变化的影响。方法:选取体外培养成功的毛囊120根,随机分为6组:空白对照组、试验组四组(分别加0.005%、0.001%、0.0005%、0.01%拉坦前列素)、阳性对照组(加米诺地尔125μg/mL)每组20根,培养14天。以显微镜目镜测微器测量毛囊长度。每组选取6根毛囊,掺入3H-TdR后,置于闪烁杯中液闪记数。结果:0.005%和0.001%拉坦前列素组毛囊毛发生长速度较其它组快,0.01%拉坦前列素组较其它组慢,差异有统计学意义;同位素3H-TdR摄入率值的比较结果与毛囊生长长度一致。结论:拉坦前列素对人头皮毛囊毛发生长的作用取决于药物浓度(低浓度起促进作用,高浓度起抑制作用);可能的机制为促进毛囊生长,抑制毛囊进入休止期。     

Morphometry of human terminal and vellus hair follicles

Previous studies suggest that drug delivery systems based on particles can be used to deposit active compounds in hair follicles and to target hair follicle-associated cell populations. The development of application protocols is complicated by the fact that there is no information available on the size and the position of key target structures in the different hair follicle types and their intra- and interindividual variation. Therefore, we performed morphometric measurements on histological sections of human terminal (THF) and vellus hair follicles (VHF) from the scalp and the retroauricular region. With 3864 +/- 605 microm and 580 +/- 84 microm in THF compared to 646 +/- 140 microm and 225 +/- 34 microm in VHF, the total length and the length of the infundibulum differed significantly as determined by paired t-test (P < 0.0001). The same level of significance was observed for the position and the length of the bulge region. The thickness of the epithelial lining was lowest in VHF (45 +/- 14 microm at 100 microm from skin surface) compared to 65 +/- 20 microm at 150 microm in THF, while the thickness of the interfollicular epidermis ranged between 64 +/- 12 microm and 99 +/- 18 microm in VHF-bearing skin and 72 +/- 16 microm and 136 +/- 37 microm in THF-bearing skin. In addition, the diameter of the hair follicle opening was determined at 50 microm intervals from the skin surface. Our data suggest that hair follicle types in defined body regions represent rather homogenous groups and that particle-based drug delivery may be a feasible approach, also in larger numbers of individuals. We provide precise information on the size and the position of key target structures in VHF and THF.     

褪黑素对毛发生长的影响

褪黑素主要是由松果体合成的一种激素,作为脊椎动物内分泌系统生物钟的同步器,其受体广泛分布于垂体、下丘脑、视网膜、肾脏和皮肤及其附属器,有着多种生理活性,按光周期信号调节生物体昼夜节律和季节节律.除了参与中枢、生殖及免疫系统的生理活动,研究表明,褪黑素与毛发生长也有密切关系,还可影响动物皮毛的季节性更替.目前已有用褪黑素制品治疗雄激素性秃发的实验性研究.     

Androgens and hair growth

Hair's importance in human communication means that abnormalities like excess hair in hirsutism or hair loss in alopecia cause psychological distress. Androgens are the main regulator of human hair follicles, changing small vellus follicles producing tiny, virtually invisible hairs into larger intermediate and terminal follicles making bigger, pigmented hairs. The response to androgens varies with the body site as it is specific to the hair follicle itself. Normally around puberty, androgens stimulate axillary and pubic hair in both sexes, plus the beard, etc. in men, while later they may also inhibit scalp hair growth causing androgenetic alopecia. Androgens act within the follicle to alter the mesenchyme-epithelial cell interactions, changing the length of time the hair is growing, the dermal papilla size and dermal papilla cell, keratinocyte and melanocyte activity. Greater understanding of the mechanisms of androgen action in follicles should improve therapies for poorly controlled hair disorders like hirsutism and alopecia.     

African hair growth parameters

BACKGROUND: Hair growth parameters have been studied mostly in caucasian hair, whereas few data on African hair have been reported in the literature. OBJECTIVES: To evaluate hair growth characteristics of African volunteers born in Africa. METHODS: Thirty-eight young adults (19 women, 19 men, mean +/- SD age 27 +/- 10 years), native of central and western Africa, took part in the study. Phototrichograms were performed in order to record three parameters of hair growth: hair density, telogen percentage and rate of growth. For each volunteer, three regions of the scalp, namely vertex, temporal and occipital areas, were assessed. RESULTS: Hair density varied from 90 to 290 hairs cm(-2), with higher counts on the vertex. No significant difference between men and women was recorded. Telogen percentage showed wide variations, from 2 to 46%, with higher levels on the temporal area and in men. The rate of growth fluctuated from 150 to 363 microm day(-1) with no difference related either to gender or to scalp region. These data were compared with those previously obtained in caucasian volunteers of comparable age, and showed significant differences between the two ethnic groups in all three parameters studied. Hair density in African volunteers was lower than that in caucasians (mean +/- SD 190 +/- 40 and 227 +/- 55 hairs cm(-2), respectively). African hair grew at a much slower rate than caucasian hair (mean +/- SD 256 +/- 44 vs. 396 +/- 55 microm day(-1)), and telogen counts were frequently higher in African hair (mean +/- SD 18 +/- 9% vs. 14 +/- 11%). CONCLUSIONS: This study demonstrated significant differences between African and caucasian hair growth parameters, which might suggest a trend towards increased hair loss in Africans, even though it contrasts with a lower and slower incidence of the development of alopecia in Africans.     

毛发生长的评价方法

如何对毛发生长情况进行评价一直是毛囊生物学研究者和皮肤科医生关注的焦点,特别是随着非那雄胺和米诺地尔治疗雄激素性秃发的广泛应用,已经越来越迫切需要准确而客观地评价毛发生长.毛发生长的主要生理性参数包括:毛发的密度、直径、毛发的线性生长速度和毛发循环的比例等,其中,休止期胜长期毛囊的比例是反映毛发循环比例的重要参数.目前,评价毛发生长的方法包括创伤性、半创伤性和非创伤性三大类,在应用过程中各有其适应范围和优缺点.     

Soymilk reduces hair growth and hair follicle dimensions

We have recently shown that soybean-derived serine protease inhibitors and soybean extracts alter skin pigmentation, suggesting that soymilk could be used as a natural alternative to skin lightening. The present studies were initiated to examine the possible effect of STI, BBI and soymilk on hair pigmentation. Interestingly, these agents were found to affect not only hair pigmentation, but also the rate of hair growth, the dimensions of the hair follicle and hair shaft, and the appearance of the hair. The studies presented here provide first evidence, at the morphological and histological level, that soymilk and the soybean-derived serine protease inhibitors could be used as effective agents for hair care and management. These agents could reduce the rate of hair growth, decrease hair shaft dimensions and alter the pattern of melanogenic gene expression.