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PubMed2002

[Genotype, melanocortin 1 receptor and ultraviolet radiation].

Recent work on the melanocortin 1 receptor (MC1R) suggests that MC1R plays a central role in regulation of eumelanin (brown/black melanins) and phaeomelanin (red/yellow melanins) synthesis within the mammalian melanocyte. In the mouse,genetic studies show that the MC1R appears to be a unique, bifunctionally controlled receptor, activated by alpha-MSH and antagonized by agouti,both of which contribute to the variability seen in mammalian coat color. Variants of this receptor are associated with different animal's coat,human skin and hair colors. In addition, cutaneous pigmentation is a major determinant of the cutaneous response to ultraviolet radiation,and consequently of the risk of developing skin cancer. MC1R variants are a risk factor for melanoma susceptibility.

English Abstract↗
PubMed1988

Variables influencing cadmium concentrations in hair of pre-school children living in different areas of the Federal Republic of Germany.

The influence of several factors on cadmium (Cd) concentrations in the hair of 474 pre-school children was examined. The study was performed in an industrial (Duisburg) and rural area (Westfalen) of the (FRG). Season, sex, hair color, and place of residence were found to be the main factors influencing Cd levels in hair. Concentrations of Cd in samples obtained during summer were on the average nearly twice as high as those sampled during winter (geometric means: 116.1 vs. 63.7 ng/g). Boys had more Cd in their hair than girls (111.5 vs. 74.0 ng/g). Cd levels in hair decreased from red to blond, to brown, and black hair. Children living in Duisburg had more Cd in their hair than those from rural areas (103.9 vs. 77.0 ng/g). Cd content in hair was inversely related to age.

Cadmium↗
PubMed1990

[Image analytic studies of melanin granules of human hairs with transmission electron micrographs].

Using electron micrographs of human hairs, we measured the minor axis and density of melanin granules by an image analyser. The melanin density of the outer hair cortex was higher than that of the inner hair cortex, and significant differences were evident especially in the minor axis and density of melanin granules among individuals. These quantitative analyses as to the minor axis and density of hair melanin granules are a reliable tool for the measurement of hair color.

Adult↗
PubMed2002

Laser hair removal.

The presence of unwanted hair continues to plague many individuals for whom traditional methods of hair removal remain unsatisfactory. Laser and flashlamp technology now offers the potential for rapid, safe, and effective treatment of unwanted hair. An ever-increasing number of published studies have confirmed the long-term efficacy of laser and flashlamp treatment. For the most part, however, the benefits of this technology have been limited to individuals with dark hair and relatively fair skin. The remaining challenge is to develop the means to eliminate light-colored hair as well as the capability to safely treat individuals with darker skin. The rapid pace of technological advancement as well as continued studies of hair follicle biology promise to improve this field over the years to come.

Hair Removal↗
PubMed2001

Beard dermatitis due to para-phenylenediamine use in Arabic men.

The most common active ingredient in hair coloring is para-phenylenediamine (PPDA), which can produce contact dermatitis, particularly in persons who dye their scalp hair and in hairdressers. We have identified another group of patients also at risk, namely men from Arab countries, who commonly grow beards and dye them. We searched the computerized patient database at the Mayo Clinic for patients with beard dermatitis associated with dye use. Eight Arabic men presented to the Mayo Clinic between 1994 and 1999 with beard dermatitis and a positive patch test to PPDA. The lesions were described as pruritic, erythematous, papular eruptions that developed in the jaw area after each application of beard dye. The symptoms subsided after the patients discontinued use of the PPDA-containing dye and received treatment with topical corticosteroids. Allergic contact dermatitis in the beard area due to PPDA occurs in Arabic men as a result of their propensity to dye their beards.

Arabs↗
PubMed2004

The genetics of sun sensitivity in humans.

Humans vary >100-fold in their sensitivity to the harmful effects of ultraviolet radiation. The main determinants of sensitivity are melanin pigmentation and less-well-characterized differences in skin inflammation and repair processes. Pigmentation has a high heritability, but susceptibility to cancers of the skin, a key marker of sun sensitivity, is less heritable. Despite a large number of murine coat-color mutations, only one gene in humans, the melanocortin 1 receptor (MC1R), is known to account for substantial variation in skin and hair color and in skin cancer incidence. MC1R encodes a 317-amino acid G-coupled receptor that controls the relative amounts of the two major melanin classes, eumelanin and pheomelanin. Most persons with red hair are homozygous for alleles of the MC1R gene that show varying degrees of diminished function. More than 65 human MC1R alleles with nonsynonymous changes have been identified, and current evidence suggests that many of them vary in their physiological activity, such that a graded series of responses can be achieved on the basis of (i) dosage effects (of one or two alleles) and (ii) individual differences in the pharmacological profile in response to ligand. Thus, a single locus, identified within a Mendelian framework, can contribute significantly to human pigmentary variation.

Gene Dosage↗
PubMed1999

Dermatologic manifestations of Hermansky-Pudlak syndrome in patients with and without a 16-base pair duplication in the HPS1 gene.

BACKGROUND: Hermansky-Pudlak syndrome (HPS) consists of oculocutaneous albinism, a platelet storage pool deficiency, and lysosomal accumulation of ceroid lipofuscin. Patients with HPS from northwest Puerto Rico are homozygous for a 16-base pair (bp) duplication in exon 15 of HPS1, a gene on chromosome 10q23 known to cause the disorder. OBJECTIVE: To determine the dermatologic findings of patients with HPS. DESIGN: Survey of inpatients with HPS by physical examination. SETTING: National Institutes of Health Clinical Center, Bethesda, Md (a tertiary referral hospital). PATIENTS: Sixty-five patients aged 3 to 54 years were diagnosed on the basis of the absence of platelet dense bodies in individuals with albinism and a bleeding diathesis. The presence of a 16-bp duplication in HPS1 was determined by polymerase chain reaction amplification; 40 patients were homozygous for the duplication and 25 lacked the duplication. All patients with the duplication were from northwest Puerto Rico; all patients without the duplication were non-Puerto Rican except 4 from central Puerto Rico. RESULTS: Both patients homozygous for the 16-bp duplication and patients without the duplication displayed skin color ranging from white to light brown. Patients with the duplication, as well as those lacking the duplication, had hair color ranging from white to brown and eye color ranging from blue to brown. New findings in both groups of patients with HPS were melanocytic nevi with dysplastic features, acanthosis nigricans-like lesions in the axilla and neck, and trichomegaly. Eighty percent of patients with the duplication exhibited features of solar damage, including multiple freckles, stellate lentigines, actinic keratoses, and, occasionally, basal cell or squamous cell carcinomas. Only 8% of patients lacking the 16-bp duplication displayed these findings. As a group, the patients with the duplication lived closer to the equator than those without the duplication. CONCLUSION: Patients with HPS exhibit wide variation in pigmentation and dermatologic findings.

Adolescent↗
PubMed1996

Mercury in hair for a child population from Tarragona Province, Spain.

Mercury concentrations were determined in scalp hair of 233 school children aged 6-16 years. The study was carried out in three communities (Flix, Tarragona and Tortosa) from Tarragona Province (Southern Catalonia, Spain). The influence of the variables place of residence, age, sex, fish and seafood consumption, number of dental amalgam fillings, hair color, parents' occupation, and smoking habits of the household members was also examined. The geometric mean mercury concentration in hair was 0.77 microgram/g. The place of residence, sex, and the frequency in consuming fish and seafood were the variables that significantly affected hair mercury concentrations. Girls had more mercury in their hair than boys, whereas hair mercury levels were significantly correlated with the frequency in the fish and seafood consumption, with the levels being more elevated when the fish and seafood consumption was also higher. Hair mercury concentrations were also affected by the place of residence, with school children of Flix showing lower mercury concentrations than those found in children from Tarragona and Tortosa. The remaining variables had no influence on hair mercury levels.

Adolescent↗
PubMed1994

Differences in dorsal and ventral pigmentation result from regional expression of the mouse agouti gene.

The agouti coat color gene encodes a paracrine signaling molecule that controls the production of yellow and black pigment by melanocytes within hair follicles. Some agouti alleles affect the dorsum and ventrum independently, which has provided the basis for speculation that agouti gene action in different regions of the body is controlled by distinct genetic loci that are closely linked. Using a combination of cDNA cloning and RNA expression studies, we find that alternative isoforms of agouti mRNA contain different noncoding first exons located 100 kb apart, whose patterns of expression indicate independent control by regulatory elements that are either ventral specific or hair cycle specific. These results demonstrate that the apparent genetic complexity of the agouti locus is explained by the existence of multiple regulatory elements exerting control over a single coding sequence and provide a conceptual basis for understanding differences in dorsal and ventral hair coloration in many mammalian species. The ventral-specific agouti isoform represents an example of a transcript whose expression is restricted to ventral skin and provide an approach to investigate the mechanisms by which dorsal-ventral differences in gene expression are established and maintained.

Age Factors↗
PubMed1975

Trace elements in hair, as related to exposure in metropolitan New York.

Previous studies have revealed that trace element concentrations in hair can reflect exposure in cases of frank poisoning and deficiency. This study reports significant correlations within a single metropolitan area between trace-element content of hair and exposure (as measured by analyses for the corresponding elements in dustfall or housedust) for Ba, Cr, Pb, Hg, Ni, Sn, and V. Age, sex, hair color, and smoking habits were factors included in the statistical evaluation. Several metals increase and decrease together in the hair specimens, in agreement with trends reported for other human tissues.

Adult↗
PubMed2002

Color and genomic ancestry in Brazilians.

This work was undertaken to ascertain to what degree the physical appearance of a Brazilian individual was predictive of genomic African ancestry. Using a panel of 10 population-specific alleles, we assigned to each person an African ancestry index (AAI). The procedure was able to tell apart, with no overlaps, 20 males from northern Portugal from 20 males from São Tomé Island on the west coast of Africa. We also tested 10 Brazilian Amerindians and observed that their AAI values fell in the same range as the Europeans. Finally, we studied two different Brazilian population samples. The first consisted of 173 individuals from a rural Southeastern community, clinically classified according to their Color (white, black, or intermediate) with a multivariate evaluation based on skin pigmentation in the medial part of the arm, hair color and texture, and the shape of the nose and lips. In contrast to the clear-cut results with the African and European samples, our results showed large variances and extensive overlaps among the three Color categories. We next embarked on a study of 200 unrelated Brazilian white males who originated from cosmopolitan centers of the four major geographic regions of the country. The results showed AAI values intermediate between Europeans and Africans, even in southern Brazil, a region predominantly peopled by European immigrants. Our data suggest that in Brazil, at an individual level, color, as determined by physical evaluation, is a poor predictor of genomic African ancestry, estimated by molecular markers.

Africa↗
PubMed2004

Final report on the safety assessment of 6-Amino-m-Cresol, 6-Amino-o-Cresol, 4-Amino-m-Cresol, 5-Amino-4-Chloro-o-Cresol, 5-Amino-6-Chloro-o-Cresol, and 4-Chloro-2-Aminophenol.

Each of these ingredients function as hair colorants. 5-Amino-4-Chloro-o-Cresol and 5-Amino-6-Chloro-o-Cresol are identified as oxidative hair dyes, that is, they are combined with an oxidizing agent before being applied to the hair. 6-Amino-m-Cresol, 6-Amino-o-Cresol, 4-Amino-m-Cresol, and 5-Amino-4-Chloro-o-Cresol are used in oxidative hair dyes, but it is not known if they are also used in nonoxidative (semipermanent) hair dyes. No toxicologically significant impurities are present with these two ingredients. To supplement the safety test data on these ingredients, available data on related ingredients (4-amino-2-hydroxytoluene and p-,m-, and o-aminophenol) previously found safe as used by the Cosmetic Ingredient Review (CIR) Expert Panel were summarized. 5-Amino-4-Chloro-o-Cresol and 5-Amino-6-Chloro-o-Cresol do not absorb significant ultraviolet radiation in the UVB region and none in the UVA region, although 4-Amino-m-Cresol had a symmetrical UV absorption peak at 300 nm. Percutaneous penetration of 5-Amino-4-Chloro-o-Cresol and 5-Amino-6-Chloro-o-Cresol alone was significant, but when combined with oxidative developer, skin absorption was extremely low. Both of these dyes are excreted rapidly via the urine. Repeated exposure of animal skin to 5-Amino-4-Chloro-o-Cresol and 5-Amino-6-Chloro-o-Cresol failed to produce any cumulative irritation and single exposures up to 10%were not irritating to animal skin. 5-Amino-4-Chloro-o-Cresol and 5-Amino-6-Chloro-o-Cresol combined with oxidizer were not sensitizers in guinea pig maximization tests. Ocular irritation resulted from exposure of animals to undiluted 5-Amino-4-Chloro-o-Cresol, but not to a 5%solution. Only minor irritation was observed with 5%5-Amino-6-Chloro-o-Cresol. Subchronic toxicity testing in animals using 5-Amino-4-Chloro-o-Cresol, 5-Amino-6-Chloro-o-Cresol, and 4-Amino-m-Cresol did not yield any adverse reactions. 6-Amino-m-Cresol and 4-Amino-m-Cresol were generally not mutagenic in in vitro and in vivo tests. Exposure to 5-Amino-4-Chloro-o-Cresol, 5-Amino-6-Chloro-o-Cresol, 6-Amino-m-Cresol and 4-Amino-m-Cresol from cosmetics were several orders of magnitude below developmental toxicity no-observed-adverse effect levels (NOAELs). Although irritation data on several ingredients are absent, products containing these ingredients must include a caution statement and patch test instructions for determining whether the product causes skin irritation. The Expert Panel expects that following this procedure would identify individuals who would have an adverse reaction and allow them to avoid significant exposures. These compounds, when tested alone, are moderate skin sensitizers, but when combined with the developer, these ingredients are not sensitizers in animal tests. This information, coupled with the available animal test data, supports the safety of these ingredients in oxidative hair dyes. In the absence of systemic toxicity data, however, the available data are insufficient to support the safety of 6-Amino-o-Cresol and 4-Chloro-2-Aminophenol in semipermanent hair dyes. The types of data required for these two ingredients for this use include (1) physical and chemical properties, including the octanol/water partition coefficient; (2) impurities data, especially regarding the presence of m-cresol, other organic molecules, and heavy metals; (3) data demonstrating that the metabolism is similar to that of 4-amino-2-hydroxytoluene and/or p-,m-, and o-aminophenol, or 28-day dermal toxicity with histopathology, dermal reproductive toxicity data, and an in vitro genotoxicity study for 6-Amino-o-Cresol and one genotoxicity study in a mammalian system; if positive, a 2-year dermal carcinogenicity study using National Toxicology Program methods may be needed.

Animals↗
PubMed2006

The use of a constant spectrum, uniform temporal profile intense pulsed light source for long-term hair removal in Asian skin.

Phototherapy has become a treatment of choice in many areas of medicine. Light can deliver energy to tissue selectively, targeting specific structures in order to induce the desired therapeutic outcome. For the safe and effective removal of unwanted hair, the key optical parameters are wavelength, pulse duration and energy density, and can vary dependent upon skin and hair color. In recent years, the use of broad spectrum white light sources has proved to be safe and efficacious in the removal of hair with minimal short- or long-term side effects. Whilst these highly flexible devices can achieve the desired results, there is scope for improvement. There are two key limitations to these devices: an inability to produce a 'true' long pulse matched to the thermal relaxation time of the hair structure and fluctuations in the output spectrum can lead to ineffective treatment with an increased risk of side effects. This paper describes an alternative approach to producing long pulse, constant spectrum optical pulses and presents clinical data showing improved efficacy in long-term hair removal.

Adult↗
PubMed2002

The long-term results of ruby laser depilation in a consecutive series of 346 patients.

The goal of this study was to prospectively assess the long-term results of ruby laser depilation in 346 consecutive patients who underwent hair removal at 402 anatomical sites. The patients were treated using a ruby laser, with mean power ranging from 8.6 J to 15.7 J according to skin type. Results were assessed using two outcome measures-the percentage reduction in hair density and the hair-free interval. The median reduction in hair density was 55 percent (range, 0 to 100 percent) at a median time of 1 year after the last treatment session. The median hair-free interval was 8 weeks. Patients underwent a median number of four treatment sessions. Forty-three of the 346 patients were treated at more than one anatomical site. Of the sites treated, 75 percent reduction in hair density was achieved in 22 percent, 90 percent reduction was achieved in 2.2 percent, and complete depilation was achieved in only 0.7 percent. Darker colored hair was more effectively treated. Treatment efficacy was not affected by anatomical site, with the exception of the faces of male patients, which were found to be particularly resistant to treatment. There was a significant correlation between the number of treatments given and the outcome. The overall complication rate was 9.0 percent (36 of 402 sites) with respect to pigmentary changes and blistering, but varied according to Fitzpatrick skin type. The complication rate was highest in skin types V and VI (24.7 percent), with no complications in skin type I. Although a greater than 50 percent reduction in hair density was achieved in half of the 346 patients treated, complete depilation was achieved in only an extremely limited number of patients.

Adult↗
PubMedDate not supplied

Hair photoprotection by dyes.

We have found that hair dyes protect hair against photodamage. The efficacy of photoprotection of dye products has been measured by monitoring the tensile strength of hair fibers and the integrity of the disulfide bonds in the fibers. Although the hair dyed with permanent dye products are initially weakened due to oxidative chemical damage, they also show a slower rate of degradation upon photoirradiation, compared to the undyed hair. Thus, a less appreciated benefit of using hair colors is their ability to provide protection against sun damage.

Hair↗
PubMed2000

Multifactorial classification of male and female androgenetic alopecia.

BACKGROUND: Various classifications of male androgenetic alopecia have been described. In fact, all the classification schemes proposed so far are only topographic. A more objective, accurate, and detailed approach to classifying baldness is needed. OBJECTIVE: To propose a dynamic multifactorial classification of certain parameters that can be quantitated and computerized. METHODS: A multifactorial classification has been developed to study parameters such as fixed distances of the face, scalp mobility and thickness, and covering power of hair. This includes density, caliber, shape, length, growth rate, and hair color. RESULTS: Classification proved to be efficient during the fluctuations of different parameters in hormonal and minoxidil treatments. It also helps to determine surgical indications of hair transplant and the stage of maximal baldness. CONCLUSION: This approach will lead to a better evaluation of the evolution of androgenetic alopecia in both sexes, either spontaneously or under treatment.

Alopecia↗
PubMed2006

A generative sketch model for human hair analysis and synthesis.

In this paper, we present a generative sketch model for human hair analysis and synthesis. We treat hair images as 2D piecewise smooth vector (flow) fields and, thus, our representation is view-based in contrast to the physically-based 3D hair models in graphics. The generative model has three levels. The bottom level is the high-frequency band of the hair image. The middle level is a piecewise smooth vector field for the hair orientation, gradient strength, and growth directions. The top level is an attribute sketch graph for representing the discontinuities in the vector field. A sketch graph typically has a number of sketch curves which are divided into 11 types of directed primitives. Each primitive is a small window (say 5 x 7 pixels) where the orientations and growth directions are defined in parametric forms, for example, hair boundaries, occluding lines between hair strands, dividing lines on top of the hair, etc. In addition to the three level representation, we model the shading effects, i.e., the low-frequency band of the hair image, by a linear superposition of some Gaussian image bases and we encode the hair color by a color map. The inference algorithm is divided into two stages: 1) We compute the undirected orientation field and sketch graph from an input image and 2) we compute the hair growth direction forthe sketch curves and the orientation field using a Swendsen-Wang cut algorithm. Both steps maximize a joint Bayesian posterior probability. The generative model provides a straightforward way for synthesizing realistic hair images and stylistic drawings (rendering) from a sketch graph and a few Gaussian bases. The latter can be either inferred from a real hair image or input (edited) manually using a simple sketching interface. We test our algorithm on a large data set of hair images with diverse hair styles. Analysis, synthesis, and rendering results are reported in the experiments.

Algorithms↗