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PubMed1985

An inquiry into the epidemiology of melanoma.

The authors conducted a study of 404 melanoma patients and 521 control patients of both sexes at Roswell Park Memorial Institute. As have previous investigators, they found that higher risk attaches to upper socioeconomic status, as measured by occupation and education, lightness of complexion and hair, and amount of blue in the admixture of eye color. The authors also found a higher risk among individuals who reacted to sun exposure by burning, blistering, or freckling rather than by tanning. A particular concern was to measure risk associated with exposure to the sun. As have two other investigators, they found that risk decreased with increasing exposure, suggesting either that individuals continually exposed to the sun have less risk because of tanning, or that susceptibles purposely avoid sun exposure, or both. The fact that melanoma occurs with greater frequency on sites exposed to the sun suggests that sun exposure plays a part. These studies showed a dose-response increase in risk (odds ratios of up to 4 for males and over 6 for females) with increases in number of traits possessed, such as light complexion, and burning or freckling in response to sun exposure. This is consistent with the authors' earlier finding of a strong familial aggregation of melanoma.

Adult↗
PubMed2003

The biology of melanocytes.

In veterinary medicine, our understanding of the biology and regulation of melanocytic function is mostly based on information realized from human and murine studies. Improved understanding of the biology of melanocytes is needed to develop more effective treatment regimens for malignant melanoma and other melanocytic disorders. In vertebrates, melanocytes are well known for their role in skin pigmentation, hair and feather coloration, and for their ability to produce and distribute melanin to surrounding keratinocytes. Enzymes involved in melanin synthesis are present exclusively in melanosomes. The type of melanin synthesized by melanocytes in mammals is regulated at a genetic, biochemical and environmental level. These regulatory factors affect not only the phenotypic appearance, but also the photoprotective properties of melanin. This review addresses the biology of melanocytes, melanin synthesis and the photoprotective properties of melanin.

Animals↗
PubMed2003

The role of melanocortin-1 receptor polymorphism in skin cancer risk phenotypes.

We have examined melanocortin-1 receptor (MC1R) variant allele frequencies in the general population and in a collection of adolescent dizygotic and monozygotic twins to determine statistical associations of pigmentation phenotypes with increased skin cancer risk. This included hair and skin color, freckling, mole count and sun exposed skin reflectance. Nine variants were studied and designated as either strong R (OR = 63; 95% CI 32-140) or weak r (OR = 5; 95% CI 3-11) red hair alleles. Penetrance of each MC1R variant allele was consistent with an allelic model where effects were multiplicative for red hair but additive for skin reflectance. To assess the interaction of the brown eye color gene BEY2/OCA2 on the phenotypic effects of variant MC1R alleles we imputed OCA2 genotype in the twin collection. A modifying effect of OCA2 on MC1R variant alleles was seen on constitutive skin color, freckling and mole count. In order to study the individual effects of these variants on pigmentation phenotype we have established a series of human primary melanocyte strains genotyped for the MC1R receptor. These include strains which are MC1R wild-type consensus, variant heterozygotes, and homozygotes for strong R alleles Arg151Cys and Arg160Trp. Ultrastructural analysis demonstrated that only consensus strains contained stage III and IV melanosomes in their terminal dendrites whereas Arg151Cys and Arg160Trp homozygous strains contained only immature stage I and II melanosomes. Such genetic association studies combined with the functional analysis of MC1R variant alleles in melanocytic cells should provide a link in understanding the association between pigmentary phototypes and skin cancer risk.

Alleles↗
PubMedDate not supplied

Dose-concentration relationships in hair from subjects in a controlled heroin-maintenance program.

Hair specimens were collected from the vertex area of 20 subjects taking part in a heroin-maintenance program. Subjects were administered, under controlled conditions, heroin hydrochloride in 2 or 3 doses/day intravenously. Heroin doses ranged from 30 to 800 mg/day, and were self-administered. In all cases, a 4-cm segment from the proximal zone (root) was analyzed, which corresponded to about 100 days of hair growth. During that period, total heroin administered ranged from 14,100 to 71,540 mg. All special features of hair such as coloring, bleaching, etc. were noted. Each sample was washed twice with dichloromethane (5 mL, 2 min) and, after drying, cut into small pieces of approximately 1 mm. A 30-35-mg aliquot was incubated overnight at 45 degrees C in 1 mL methanol in the presence of 200 ng of heroin-d9, 6-acetylmorphine-d3, and morphine-d3. The methanolic extract was then evaporated to dryness, and the residue was derivatized by silylation (BSTFA + 1% TMCS). Drugs were analyzed by gas chromatography-mass spectrometry in electron impact mode. Limits of quantitation were set to 0.1 ng/mg. Concentrations ranged from 0 to 4.53, 0.38 to 10.11, and 0.71 to 5.20 ng/mg for heroin, 6-acetylmorphine, and morphine, respectively. 6-Acetylmorphine was the major analyte present in hair in all but five cases. Heroin was present in the highest concentration in three cases, and morphine was the major metabolite in two cases, probably because of hydrolysis. Subjects tested positive for heroin in all but two cases. No correlation between the doses of administered heroin and the concentrations of total opiates in hair was observed (r = 0.346). However, when considering a single analyte, it was observed that the correlation coefficient seemed to be linked to its plasma half-life. A weak correlation coefficient corresponds to a drug with a short plasma half-life, and the correlation coefficient increases when plasma half-life increases, as r = 0.12, 0.25, and 0.64 for heroin, 6-acetylmorphine, and morphine, respectively. These results suggest that using quantitative drug measurements in hair to determine the amount of drug ingested will remain inapplicable until more is known about the factors that may influence the incorporation of drugs into hair and a way to reduce the observed variability.

Adult↗
PubMedDate not supplied

Five new mutations in the Syrian hamster: furloss, fur-deficiency, juvenile gray, ashen, and quaking.

Five new mutations in the Syrian hamster are described: furloss, a simple recessive trait affecting the quality of hair; fur-deficiency, a simple recessive trait affecting the quantity of hair and longevity; juvenile gray, a simple recessive trait affecting coat color and body size; ashen, a semidominant trait affecting both coat color and quantity of hair; and quaking, a simple recessive trait affecting motor activity. Gene symbols, fs, Rfd, jg, A, and q are proposed for these mutations.

Alopecia↗
PubMed1986

Prevalence of feline leukemia virus infection among adult cats at an animal control center: association of viremia with phenotype and season.

The overall frequency of feline leukemia virus infection among 555 cats tested from the Hillsborough County Florida Animal Control facility, using a commercial enzyme-linked immunosorbent assay, was 9.4%. Among male cats, the frequency was 13.8%, which was statistically higher (P = 0.003) than that for females (5.9%). There was no statistical evidence to associate frequency of viral infection with hair length or coloration. There was an association with color distribution. The frequency of viral infection in cats with a solid color in their coat, excluding tabby, calico, and tortoise, was higher (12.2%) than the frequency in the remainder of the cats (5.5%; P = 0.011). Finally, there was a difference in frequency related to season. For the 10 months of the study, cats collected in the 5 cooler months (January, February, March, April, and October) had a frequency of 14.6%; cats obtained in the 5 warmer months (May, June, July, August, and September) had a frequency of 7.2% (P = 0.038).

Animals↗
PubMed2004

Topical application of a protein kinase C inhibitor reduces skin and hair pigmentation.

To determine whether inhibition of PKC-beta activity decreases pigmentation, paired cultures of primary human melanocytes were first pretreated with bisindolylmaleimide (Bis), a selective PKC inhibitor, or vehicle alone for 30 min, and then treated with TPA for an additional 90 min to activate PKC in the presence of Bis. Bis blocked the expected induction of tyrosinase activity by activation of PKC. Addition of a peptide corresponding to amino acids 501-511 of tyrosinase containing its PKC-beta phosphorylation site, a presumptive PKC-beta pseudosubstrate, gave similar results. To determine whether Bis reduces pigmentation in vivo, the backs of four shaved and depilated pigmented guinea pigs were UV irradiated with a solar simulator for 2 wk excluding weekends. Compared to vehicle alone, Bis (300 microM), applied twice daily to paired sites for various periods encompassing the irradiation period, decreased tanning. Bis also, although less strikingly, reduced basal epidermal melanin when topically applied twice daily, 5 d per wk, for 3 wk to shaved and depilated unirradiated skin. Moreover, topical application of Bis (100 microM) once daily for 9 d to the freshly depilated backs of 8-wk-old mice markedly lightened the color of regrowing hair. These results demonstrate that inhibiting PKC activity in vivo selectively blocks tanning and reduces basal pigmentation in the epidermis and in anagen hair shafts.

Animals↗
PubMed2005

Melanocortin-1 receptor (MC1R) gene variants and dysplastic nevi modify penetrance of CDKN2A mutations in French melanoma-prone pedigrees.

Germline mutations in CDKN2A gene predispose to melanoma with high but incomplete penetrance. Penetrance of CDKN2A gene was found to be significantly influenced by host factors (nevus phenotypes and sunburn) on one hand and by variants of MC1R gene (RHC variants consistently associated with red hair and fair skin) on the other hand. Our goal was to examine the joint effects of MC1R variants and other potential risk factors [total nevi, dysplastic nevi, pigmentary traits (skin, hair and eye color), skin reactions to sunlight, and degree of sun exposure] on CDKN2A penetrance. Clinical, genetic, and covariate data were recorded in 20 French melanoma-prone families with cosegregating CDKN2A mutations. Analysis of the cotransmission of melanoma and CDKN2A mutations was conducted by likelihood-based methods using the regressive logistic models, which can account for a variation of disease risk with age and can include the aforementioned risk factors as covariates. RHC variants, considered either alone or in the presence of pigmentation and nevus phenotypes, were found to increase significantly CDKN2A penetrance. Multivariate analysis, using a stepwise selection procedure, showed significant effects of two factors on melanoma risk in CDKN2A mutations carriers: RHC variants [odds ratio of hazard function (OR), 2.21; P = 0.03] and dysplastic nevi (OR, 2.93; P < 0.01). Such results may have important consequences to improve the prediction of melanoma risk in families.

Adult↗
PubMed2000

Determination of metal concentrations in animal hair by the ICP method: comparison of various washing procedures.

Concentrations of minor and trace elements (Mg, Ca, Fe, Ba, Cu, Zn, Cd, Ni, Al, Mn, Cr, Ti, and V) in the hair of three races of dogs (fox terrier, schnauzer, and mini schnauzer) were analyzed by the inductively coupled plasma-atomic emission spectrometry method. The influence of five washing solutions, deionized water, acetone, methanol, EDTA, and Triton X-100, on the concentrations measured in hair was investigated. Triton X-100 was found to be suitable to use for the removal of exogenous elements in multielemental hair analysis. Additionally, the results indicated that the concentration of the elements measured in the dogs' hair were similar to those reported for human hair. The relation between the element content in the dog hair and its color were similar to those found for human hair.

Animals↗
PubMed1997

Influence of pigmentation on the codeine content of hair fibers in guinea pigs.

Tortoise shell guinea pigs (n = 7) were administered codeine (1 mg/mL codeine-base) in their drinking water for 3 weeks. Black, reddish-brown and white hair was collected separately from each animal before and after treatment. The hair samples were analyzed by GC/MS. The experiment showed positive results for all hair fibers with large individual variability of drug incorporation. Low drug intake resulted in small differences of the drug content in hair fibers different in color, whereas in cases of high drug intake a strong influence of hair pigmentation on the analytical results was observed. The highest drug content was always found in black hair samples, non-pigmented hair showed the lowest drug concentrations and the drug content in reddish-brown fibers was less than in black hair samples from the same animal. From the results it was concluded, that eumelanins rather than phenomelanins are the decisive factor for codeine-melanin binding in hair and the amount of drug intake was suggested to determine the relevance of hair pigmentation on the analytical results.

Animals↗
PubMed2006

Hair analysis for ketamine and its metabolites.

A rapid and sensitive method was developed for the simultaneous identification and quantitation of ketamine (K) and its major metabolite, norketamine (NK) in hair. After decontamination, the hair sample was incubated and extracted, and analyzed by gas chromatography-mass spectrometry (GC-MS). Limits of quantitation were found to be 0.05 ng/mg. Hair segments in black color were collected from 15 K abusers. Based on an experiment with 15 cavies with black, white, and brown hair, the mechanism of incorporation of K into hair was investigated. After shaving hair on the back of the cavies (8 cm x 4 cm), they were separated into three groups and administered intraperitoneally once a day for 7 successive days with high, medium, and low doses of K, respectively. Two days after this, hair segments with different colors were shaved. There was a direct correlation between the concentration of K in cavy hair and the dose and DHNK was detected only in high dosage group. The concentration of K increased in the order of white, brown, and black hair. The possible factors responsible for the incorporation of K and its metabolites in hair were discussed.

Anesthetics, Dissociative↗
PubMed2006

Investigation of the role of the agouti signaling protein gene (ASIP) in coat color evolution in primates.

We investigated variation in the gene encoding the agouti signaling protein (ASIP) in relation to coat color evolution in primates. We found little evidence that mutations in the coding region of ASIP have been involved in color changes among closely related primate species. Among many closely related species with differing coat color, the coding region of ASIP was identical. In two cases (Sulawesi macaque and black lion tamarin) where species with almost completely black coat color had derived point mutations in exon 4 of the ASIP coding sequence, the same mutations did not alter coloration in other mammals and so probably do not affect ASIP function. Evolutionary reconstructions of two key phenotypes that are typically related to ASIP function--transverse phaeomelanin bands on hairs and pale ventral coloration--showed that these usually evolved concurrently, suggesting that loci acting downstream of ASIP may be involved. Analysis of dN/dS ratios revealed a likely change in functional constraint on ASIP following loss of agouti-banded hairs + pale ventral coloration, particularly in catarrhine primates (humans, apes, and Old World monkeys). Together with previous results on a lack of association of coat color with MC1R variation, these results suggest that other loci probably have an important role in primate coat color evolution.

Agouti Signaling Protein↗
PubMedDate not supplied

Analyzing the laser-light reflection from human hair fibers. II. Deriving a measure of hair luster.

Hair shine or luster is perceived as an important, though analytically somewhat elusive, attribute of beauty, primarily associated with clean and healthy hair. Principles for the assessment of hair luster are developed that are consistent with the practical situation. These principles are related to the components of light, specularly and diffusely reflected from single hair fibers, as measured by laser-based, multiangle goniophotometry, presented in Part I. Considering various definitions of gloss, their tradition, practical implementation, and their inherent limitations for testing hair, the gloss index as a physically consistent measure of hair luster is derived from the ratio of the integral intensities of the light components. Changes of the parameter values along hair length, namely their decrease, are analyzed for hairs of different color and ethnic origin. The correlation with shine evaluations of hair tresses by panels, based on literature data, is analyzed and ascertained.

Hair↗