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PubMed2000

Melanocortin-1 receptor polymorphisms and risk of melanoma: is the association explained solely by pigmentation phenotype?

Risk of cutaneous malignant melanoma (CMM) is increased in sun-exposed whites, particularly those with a pale complexion. This study was designed to investigate the relationship of the melanocortin-1 receptor (MC1R) genotype to CMM risk, controlled for pigmentation phenotype. We report the occurrence of five common MC1R variants in an Australian population-based sample of 460 individuals with familial and sporadic CMM and 399 control individuals-and their relationship to such other risk factors as skin, hair, and eye color; freckling; and nevus count. There was a strong relationship between MC1R variants and hair color and skin type. Moreover, MC1R variants were found in 72% of the individuals with CMM, whereas only 56% of the control individuals carried at least one variant (P<.001), a finding independent of strength of family history of melanoma. Three active alleles (Arg151Cys, Arg160Trp, and Asp294His), previously associated with red hair, doubled CMM risk for each additional allele carried (odds ratio 2.0; 95% confidence interval 1. 6-2.6). No such independent association could be demonstrated with the Val60Leu and Asp84Glu variants. Among pale-skinned individuals alone, this association between CMM and MC1R variants was absent, but it persisted among those reporting a medium or olive/dark complexion. We conclude that the effect that MC1R variant alleles have on CMM is partly mediated via determination of pigmentation phenotype and that these alleles may also negate the protection normally afforded by darker skin coloring in some members of this white population.

Data Interpretation, Statistical↗
PubMedDate not supplied

[Taxonomy of the musk deer (Artiodactyla, Mammalia)].

We studied the chromosome sets and specific morphological features and phenetic traits of hair cover coloration, as well the pattern of its inheritance upon experimental hybridization. The diploid set of chromosomes in the animals from the northern part of the range contains 2n = 58 (there are two additional B-chromosomes in the Far Eastern musk deer) and is identical to that from the southern musk deer forms. Discrete polymorphic features of neck and hair cover coloration have been identified in the northern and southern musk deer, and these are used as taxonomic features. A map illustrates distribution of the established subspecies.

Animals↗
PubMed2006

Interpreting the color effect of melanin on cocaine and benzoylecgonine assays for hair analysis: brown and black samples compared.

This paper examines the hypothesis that cocaine and BE assays of hair demonstrate a putative bias effect for darker color hair samples. Although such an effect has been reported in the literature, no one has examined this claim outside the bounds of simple significance of mean difference. In this paper a large number of black and brown hair samples are compared for cocaine and BE concentration values, and this comparison is evaluated for both significance and effect size. Two innovative measures are used to assess this relationship - a calculation of effect size using Cohen's d, and the use of an ROC curve to evaluate the potential for a dark color bias. The paper reports mixed results for significance, but consistent results for effect size. There does not appear to be any significant effect for cocaine. While BE demonstrates a significant mean difference, both the effect size and the ROC analysis show the effect to be trivial.

Cocaine↗
PubMedDate not supplied

Morphologic basis of inherited coat-color dilutions of cats.

The melanin granules in hair of black, smoke, blue, Chediak-Higashi-smoke, and pink-eyed dilution cats were studied. The hair of black cats contains numerous small dark brown to black melanin granules uniformly distributed throughout all portions. The basis for the dilution in smoke cats is a paucity of melanin granules in the basal portions of the hair. Blue cat hair has a larger basic melanin granule, some very large but relatively regularly shaped granules, and a non-uniform distribution of granules. The granules in the blue cat hair resemble those in the hair of dilute mice. The Chediak-Higashi trait causes even larger basic melanin granules than the blue dilution and enlarged and relatively irregularly shaped granules. The melanin granules in the hair of the pink-eyed dilution cat are very small, and are yellowish brown compared to the dark brown to black of those of black, smoke, and blue cats.

Animals↗
PubMed1998

Quantitation of cocaine in human hair: the effect of centrifugation of hair digests.

Hair pigmentation is a critical factor in the interpretation of the concentration of certain compounds and their metabolites incorporated into hair. Melanin is responsible for the pigmentation. The color and the melanin content of human hair samples differs over a wide range. Once deposited into hair, drug may remain detectable for a period of months to years. However, if drug disposition into hair is influenced by those properties attributed to hair color, then certain persons may test positive more frequently than other persons. Removal of the melanin from hair digests prior to drug analysis may reduce the effect of melanin on the total drug concentration by excluding the drug bound to the pigment. In this study, the effect of melanin removal by centrifugation of hair digests on cocaine concentrations was investigated. Two sets of hair samples from five cocaine users were analyzed for cocaine and metabolites. A solution consisting of 10 mL of 0.5M Tris buffer (pH 6.4) to which is added 60 mg D,L-dithiothreitol, 200 mg SDS, and 200 U Proteinase K, was used to digest the hair. Two milliliters of this solution was added to 20 mg of hair and incubated at 37 degrees in a shaking water bath (90 oscillations/min) overnight. The samples were removed from the water bath and mixed. One set was centrifuged at 2000 rpm and divided into supernatant and melanin pellet. The other set was not centrifuged. Internal standards were added to all tubes. The samples were further extracted, derivatized, and analyzed by gas chromatography-mass spectrometry. A mean of 8.8% (standard deviation [SD] 7.0%) of the total cocaine concentration (supernatant and pellet) was left behind in the pellet. The same experiment was repeated except that the melanin pellet was redigested with 0.1 N HCl. After redigestion of the melanin pellet, the mean cocaine concentration in the pellet was 3.8% +/- 4.0% (mean +/- SD) of the total cocaine concentration in hair. These data demonstrate that removal of melanin from hair digests by centrifugation does not eliminate hair color bias when interpreting cocaine concentrations.

Centrifugation↗
PubMed1999

Ruby laser-assisted hair removal success in relation to anatomic factors and melanin content of hair follicles.

Ruby laser-assisted hair removal is thought to work via selective photothermolysis, which relies on light reaching the deeper layers of skin, and the absorption of light by the target chromophore, melanin. It is therefore possible that efficacy of treatment is affected by anatomic factors that determine the amount of light reaching the hair bulbs (i.e., skin color, depth of intracutaneous hair, epidermal thickness and dermal density) and the melanin content of hair. To examine this hypothesis, a prospective study was performed. Forty-eight volunteers were treated with the Chromos 694 Depilation Ruby Laser at a single standard fluence of 11 J/cm2. Treatment efficacy was determined by measuring hair density at 3 and 7 months after treatment. Epidermal depth and dermal density were measured from 2-mm biopsies taken before treatment, and the intracutaneous hair length was determined from plucked hair. Skin color was assessed using a spectrophotometer, and melanin content of dissolved hair was assessed using spectrophotometry. Efficacy of treatment for each patient was compared with the patient's age, intracutaneous hair length, epidermal depth, dermal density, skin color, and total melanin content and relative eumelanin content of hair. No correlation was found between the efficacy of treatment and age and the various anatomic factors. Patients with higher eumelanin content in their hair had better long-term results (Spearman rank test, p = 0.00219). The results suggested that the efficacy of treatment did not depend solely on the amount of laser light penetrating the skin but correlated well with the eumelanin content of hair. The clinical implication of this finding is discussed.

Adolescent↗
PubMed2006

Bioaccumulation and antioxidant responses in goldfish Carassius auratus under HC Orange No. 1 exposure.

HC Orange No. 1 is used as a color additive in hair dyes and colors. In this study, laboratory experiments were carried out to determine the accumulation of HC Orange No. 1 in goldfish and the biochemical responses in liver of freshwater goldfish Carassius auratus. Goldfish were exposed to 1.0 mg/L HC Orange No. 1 for 6, 12, 24, 36, 48, 60, 72, and 96 h. Results showed that the concentrations of HC Orange No. 1 in water decreased rapidly in the first 24h, and then maintained equilibrium, while the concentrations of HC Orange No. 1 in goldfish reached a maximum level at 24 h, and then descended appreciably. For the total loss of HC Orange No. 1 in water 16.4% was due to the accumulation by goldfish, and approximately 57.6% resulted from metabolism by goldfish. After calculation, lgBCF is equal to 2.11. Hence, HC Orange bioaccumulation is significantly affected by a fast metabolic clearance in goldfish. Next, we investigated the biochemical responses in liver of freshwater goldfish C. auratus. It was shown that the hepatic antioxidant defense parameters of goldfish, including the contents of reduced glutathione (GSH) and activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), were highly sensitive to HC Orange No. 1 exposure, accompanied by changes of HC Orange No. 1 accumulation in liver tissue. Changes of these parameters indicated that there was an increase in the production of oxyradicals by goldfish and the presence of oxidative stress. These findings also implied that glutathione as well as other antioxidant enzymes function in the protection against HC Orange No. 1 toxicity and that these antioxidants provide a first line of defense against HC Orange No. 1, before the induction of any other detoxification mechanism.

Animals↗
PubMed1995

Glutathione plays a key role in the depigmenting and melanocytotoxic action of N-acetyl-4-S-cysteaminylphenol in black and yellow hair follicles.

This study examined the effect of glutathione on the in vivo depigmenting potency of N-acetyl-4-S-cysteaminylphenol (N-acetyl-4-S-CAP) in black and yellow mice after multiple intraperitoneal injections on 10 consecutive days. In black mice (C57BL/6J, a/a), N-acetyl-4-S-CAP showed dose-dependent depigmenting potency (0.5, 1.0, and 2.0 mmol/kg), which was in parallel to the tissue eumelanin content (98%, 28%, and 3% of controls, respectively) and to the tissue glutathione content (94%, 85%, and 76%, respectively). In lethal yellow mice (C57BL/6J, Ay/a), only a dose of 2.0 mmol/kg showed the color change of hair to dark, not to white as seen in black mice. This was reflected by the decrease of pheomelanin content (56%) and the increase of eumelanin content (28% of black mice). The simultaneous administration of N-acetyl-cysteine, which up-regulated glutathione content, completely abolished the depigmenting potency of N-acetyl-4-S-CAP, whereas administration of buthionine sulfoximine, which depleted the tissue glutathione content, enhanced the depigmenting potency of N-acetyl-4-S-CAP in black hair. In yellow mice, the darkening of hair follicles by 2.0 mmol/kg of N-acetyl-4-S-CAP was completely abolished by the combined administration of N-acetyl-cysteine, with the resulting hair color the same as in controls, whereas combined administration with buthionine sulfoximine caused some whitening of yellow hair follicles. Our data indicate that the tissue content of glutathione regulates melanocytotoxicity and depigmenting potency of N-acetyl-4-S-CAP and that this alteration of glutathione content may switch the melanogenesis type from pheomelanin to eumelanin.

Animals↗
PubMed1988

Magnetic field effects on pineal N-acetyltransferase activity and melatonin content in the gerbil--role of pigmentation and sex.

The ambient geomagnetic field influences a variety of biological phenomena. Electrical and biochemical parameters of the rodent pineal gland are influenced by the alteration of weak magnetic fields (MF), the magnetic receptor probably residing in the retina. However, open questions concern the role of retinal pigmentation as well as species- and sex-specific differences in MF perception. We therefore exposed male and female naturally pigmented and albino Mongolian gerbils, as well as Sprague-Dawley (SD) rats to a 60 degrees rotation of the horizontal component of the ambient MF. Alteration of nocturnal pineal melatonin content and N-acetyltransferase (NAT) activity were utilized as a parameter for assessing magneto-sensitivity. In pigmented gerbils, MF exposure resulted in no significant changes in pineal melatonin synthesis. In contrast, albino gerbils and SD rats exhibited--regardless of sex--significant decreases in pineal NAT activity and melatonin content following MF exposure. These results suggest that in rodents hypopigmentation appears to favor magnetoperception. The available evidence indicates that the pigmentation of the retina could play a crucial role.

Acetyltransferases↗
PubMedDate not supplied

Maltese dilution of domestic cats. A generalized cutaneous albinism lacking ocular involvement.

The Maltese dilution is an autosomal recessive trait of cats that dilutes black cats to blue, and orange cats to cream. The pigmented cutaneous and ocular tissues of Maltese dilution and control cats were examined and compared by light microscopy. Most of the melanin granules in all of the pigmented cutaneous tissues of the Maltese dilution cats were aggregated together into large clumps. However, none of the intraocular tissues containing melanin producing cells of either neural crest or optic cup embryologic origin contained clumped melanin granules. It is concluded that the Maltese dilution trait is a unique generalized albinism without ocular involvement.

Albinism↗
PubMedDate not supplied

Platinum coat color locus in the deer mouse.

Platinum coat color in the deer mouse, Peromyscus maniculatus, is an autosomal recessive trait marking a locus, pt, distinct from silver (si), albino (c), blonde (bl), brown (b), and agouti (a). Platinum deer mice are conspicuously pale, with light ears and tail stripe. The pewter trait is allelic with and phenotypically identical to platinum, and represents an independent recurrence of this mutant. The rate of recoveries of coat color mutations from wild deer mice is consistent with available data for recurring mutation rates balanced by strong selection against the recessive phenotype.

Alleles↗
PubMed2006

The Tabby cat locus maps to feline chromosome B1.

The Tabby markings of the domestic cat are unique coat patterns for which no causative candidate gene has been inferred from other mammals. In this study, a genome scan was performed on a large pedigree of cats that segregated for Tabby coat markings, specifically for the Abyssinian (Ta-) and blotched (tbtb) phenotypes. There was linkage between the Tabby locus and eight markers on cat chromosome B1. The most significant linkage was between marker FCA700 and Tabby (Z = 7.56, theta = 0.03). Two additional markers in the region supported linkage, although not with significant LOD scores. Pairwise analysis of the markers supported the published genetic map of the cat, although additional meioses are required to refine the region. The linked markers cover a 17-cM region and flank an evolutionary breakpoint, suggesting that the Tabby gene has a homologue on either human chromosome 4 or 8. Alternatively, Tabby could be a unique locus in cats.

Animals↗
PubMed1993

Multicentric squamous cell carcinoma in situ resembling Bowen's disease in cats.

Multicentric squamous cell carcinoma in situ was studied in 12 cats (eight castrated males and four spayed females). The neoplasms occurred in middle-aged to old (mean age = 12 years) mixed-breed cats with a variety of hair-coat colors. The lesions were found in haired pigmented regions of the skin, including the trunk, limbs, feet, head, and neck, and were unrelated to exposure to sunlight. Lesions occurred at multiple sites in nine cats and at solitary sites in three cats and were from 0.5 cm to 3.0 cm in diameter, irregular, slightly elevated, plaque-like or papillated, and partially alopecic. Histologically, the lesions consisted of sharply demarcated regions of neoplastic, keratinocytic infiltration of the epidermal and follicular infundibular epithelium. Neoplastic cells were confined to the epithelium without frank invasion of the dermis. Two histologic subclasses of multicentric squamous cell carcinoma in situ were identified, the irregular nonhyperkeratotic type and the verrucous hyperkeratotic type. Three cats also had invasive squamous cell carcinoma adjacent to lesions characteristic of multicentric squamous cell carcinoma in situ. Grossly, these were solitary 2.0-4.0 cm-diameter firm, crusted, crateriform cutaneous masses. During follow-up periods of 4 to 20 months (mean follow-up period = 11 months), neoplasms did not recur locally after surgical excision; however, similar lesions developed at new sites in four cats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Linkage studies on 13 biochemical loci and 2 coat color loci in a [(BN x TM) x TM] backcross progeny of the rat (Rattus norvegicus).

In a [(BN X TM) X TM] backcross progeny of rats, nine significant linkage associations were found among 105 pairwise combinations of 15 loci. After comparing this with other published data and data of personal communications, we considered that the d gene we tentatively designated may be identical to the gene for pink-eyed dilution (p), and that the associations of Gc-Hbb, RT1-h, and Gc-Fh were due to chance rather than real linkage. The linkages obtained in this study, therefore, were Hbb-p (26.5 +/- 5.5) in LG I, Mup-1-Acon-1 (12.5 +/- 4.1) in LG II, Hao-1-Svp-1 (23.8 +/- 6.6) in LG IV, Es-1-Es-3 (17.2 +/- 4.7) in LG V, h-Gc (10.9 +/- 3.3) in LG VI, and Fh-Pep-3 (32.3 +/- 5.9) in LG X.

Alleles↗