Immortalization of mouse melanocytes carrying mutations in various pigmentation genes.
Explore the source record for details and available documents.
Animals↗
SEARCH · Search PubMed
Results for “Hair Color”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The eumelanin and pheomelanin contents in dorsal hairs of female recessive yellow mice are greater than in male.
BACKGROUND: The murine recessive yellow (Mc1r(e)) is a loss-of-function mutation in the receptor for alpha-melanocyte-stimulating hormone (MSH), melanocortin receptor 1 (MC1R), and produces yellow coats by inducing pheomelanin synthesis in hair follicular melanocytes. OBJECTIVE: It is not known whether the Mc1r(e) mutation affects pheomelanin synthesis in other skin sites. In this study, the eumelanin and pheomelanin contents in the epidermis and dermis as well as hairs of wild-type and mutant mice were measured. MATERIALS AND METHODS: The content of melanin was measured by high performance liquid chromatography. RESULTS: The eumelanin contents in the epidermis and dermis of newborn wild-type (Mc1r(+)/Mc1r(+)) mice (0.5, 3.5, 5.5, and 7.5 days) were much greater than those of mutant (Mc1r(e)/Mc1r(e)) mice, whereas the pheomelanin contents in the epidermis and dermis of mutant mice were much greater than those of wild-type mice. No sex differences in the contents of eumelanin and pheomalanin in the epidermis and dermis both in mutant and wild-type mice were observed. The eumelanin contents in mutant hairs (5-week-old) was much smaller than in wild-type hairs, whereas the pheomelanin contents in mutant hairs was much greater than in wild-type hairs. However, the eumelanin and pheomelanin contents in mutant female hairs were greater than in male. These sex differences were not observed in wild-type mice. CONCLUSION: The Mc1r(e) gene stimulates pheomelanin synthesis in the epidermis, dermis and hair follicles. In addition, eumelanin and pheomelanin contents in Mc1r(e)/Mc1r(e) hairs may be influenced by the sex difference.
Animals↗
Sensorineural hearing loss, early greying, and essential tremor: a new hereditary syndrome?
OBJECTIVE: To present a syndrome composed of sensorineural hearing loss, early greying of scalp hair, and adult-onset essential tremor. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary care academic hospital. RESULTS: Three individuals were seen with this triad, each with family members with similar features. Our patients are a 65-year-old man and two women in their 40s. Two noted hearing loss in adulthood, one as a child. All had complete greying in their 20s. The women developed essential tremor in their 20s, and the man in his 50s. All individuals have blue eyes without heterochromia. Additional evaluation failed to further categorize these patients. Each has two or more immediate family members with a combination of these findings. Molecular genetic testing suggests this is not a variant of Waardenburg syndrome. CONCLUSION: We believe this represents a previously unreported hereditary syndrome. SIGNIFICANCE: This new syndrome should be considered in the context of other syndromes involving audition, pigmentation, and movement.
Adult↗
Detection of enrofloxacin and its metabolite ciprofloxacin in equine hair.
Hair analysis to detect drug administration has not been studied extensively in horses. This study aimed to (a) develop an analytical method for enrofloxacin and its metabolite ciprofloxacin in mane and tail hair, (b) relate measured values to doses, routes of administration, hair colour, and (c) demonstrate long-term detectability. Samples were extracted in trifluoroacetic acid at 70 degrees C. Extracts were cleaned-up by solid-phase extraction and analysed by high-performance liquid chromatography with UV-diode array detection. Analyte recoveries were > 87%. Horses were sampled after therapeutic enrofloxacin administration either orally at 7.5 mg/kg daily for 3-13 days or twice daily for 10-14 days (Group 1, n=7) or intravenously at 5.0 mg/kg daily for 12 and 15 days (Group 2, n=2). Enrofloxacin and ciprofloxacin were detected at concentrations up to 452 and 19 ng/mg, respectively, up to 10 months post-treatment. In vitro, enrofloxacin and ciprofloxacin were extensively bound to melanin (> 96%) and in vivo, their uptake was 40-fold greater in black than white hair. Enrofloxacin and ciprofloxacin concentrations correlated to enrofloxacin dose (r2=0.777 and r2=0.769). Enrofloxacin:ciprofloxacin ratios were 21:1 and 13:1 following intravenous and oral administration, respectively. Longitudinal analyte distributions correlated to treatment-sampling interval.
Administration, Oral↗
Sunlight exposure and pathogenesis of uveal melanoma.
Uveal melanoma is the most frequent primary malignant intraocular tumor of adults. Among various non-modifiable risk factors, Caucasian race seems to be the most significant with light skin color, blond hair, and blue eyes being specific risk factors. The racial predisposition to uveal melanoma have been explained on the basis of susceptibility of Caucasian race to oncogenic effects of sunlight. Although there is ample evidence in support of this hypothesis in regard to skin melanoma, the evidence in regard to uveal melanoma is insufficient and contradictory. In the following review, we examine physiologic, epidemiological, and genetic data in order to determine the role of sunlight exposure in the pathogenesis of uveal melanoma.
Environmental Exposure↗
How the mouse got its spots.
One's ultimate phenotype is the result of a combination of genotype and environment, and includes a poorly understood component termed "developmental noise". This "developmental noise", also known as "intangible variation", is rarely discussed even though it appears to make a significant contribution to the variance of quantitative traits within a species. The molecular basis of developmental noise remains unknown, but it appears to be established in embryonic development and to be retained for the life of the organism. We propose that the molecular basis of developmental noise is, at least in some instances, the epigenetic state of the genome. The stochastic nature of the establishment of epigenetic state, combined with its heritability during mitosis, provides all of the essential components for developmental noise.
Animals↗
Interactions between Sox10, Edn3 and Ednrb during enteric nervous system and melanocyte development.
The requirement for SOX10 and endothelin-3/EDNRB signalling pathway during enteric nervous system (ENS) and melanocyte development, as well as their alterations in Waardenburg-Hirschsprung disease (hypopigmentation, deafness and absence of enteric ganglia) are well established. Here, we analysed the genetic interactions between these genes during ENS and melanocyte development. Through phenotype analysis of Sox10;Ednrb and Sox10;Edn3 double mutants, we show that a coordinate and balanced interaction between these molecules is required for normal ENS and melanocyte development. Indeed, double mutants present with a severe increase in white spotting, absence of melanocytes within the inner ear, and in the stria vascularis in particular, and more severe ENS defects. Moreover, we show that partial loss of Ednrb in Sox10 heterozygous mice impairs colonisation of the gut by enteric crest cells at all stages observed. However, compared to single mutants, we detected no apoptosis, cell proliferation or overall neuronal or glial differentiation defects in neural crest cells within the stomach of double mutants, but apoptosis was increased in vagal neural crest cells outside of the gut. These data will contribute to the understanding of the molecular basis of ENS, pigmentation and hearing defects observed in mouse mutants and patients carrying SOX10, EDN3 and EDNRB mutations.
Animals↗
A mouse TRAPP-related protein is involved in pigmentation.
We identified a new spontaneous recessive mutation in the mouse, mhyp (mosaic hypopigmentation), in a screen for novel proviral integration sites in a multiple ecotropic provirus mapping stock. Integration of an 8.4-kb retrovirus results in mosaic loss of coat pigment in mhyp homozygotes. Patchy loss of pigmentation in the retinal pigmented epithelial layer of the eye with abnormal melanosomes is also evident. We mapped mhyp to mouse chromosome 7 and cloned the underlying gene. mhyp is a defect in the Trappc6a gene. Expression of Trappc6a is markedly diminished in mhyp homozygotes. The normal protein, TRAPPC6A, is a subunit of the TRAPP (transport protein particle) I and II complexes. While TRAPP complexes are essential for ER-to-Golgi and intra-Golgi vesicle trafficking in yeast, TRAPP subunits participate in additional, including post-Golgi, transport events in mammals. The data implicate mammalian TRAPPC6A in vesicle trafficking during melanosome biogenesis.
Amino Acid Sequence↗
Premature gray hair and coronary artery disease.
Explore the source record for details and available documents.
Adult↗
The melanocyte stimulating hormone receptor polymorphism: association of the V92M and A294H alleles with basal cell carcinoma.
Allelic variants in the melanocyte stimulating hormone receptor (MC1R) gene are susceptibility/outcome candidates for cutaneous basal cell carcinoma (BCC). We identified the val92met (V92M) and asp294his (A294H) alleles in 311 cases and 190 controls. The cases included four homo- and 53 heterozygotes for V92M and 12 heterozygotes for A294H and two compound heterozygotes (V92M/A294H). Allele frequencies were similar in controls. In the cases, we found no association between the alleles and skin type though A294H was more common in those with red hair (4/19) than with other hair colours (6/163) (P = 0.012). V92M was not associated with BCC numbers. Cases with A294H had fewer BCC in comparison with those without the allele though the difference was not significant. After inclusion of red hair in the model, A294H was significantly associated with fewer tumours. While MCIR alleles are attractive candidates for BCC, the variants studied did not influence susceptibility. The association with outcome was relatively weak. The large number of MC1R alleles and their low frequency, make assessment of the importance of this gene in the pathogenesis of skin cancers difficult.
Alleles↗
A familial defect in cellular chemotaxis associated with redheadedness and recurrent infection.
This study describes a familial defect in polymorphonuclear leukocyte chemotaxis associated with redheadedness and recurrent infection in two of six siblings. Laboratory data indicate that this defect in chemotaxis is not associated with a concurrent defect in leukocyte bactericidal activity. Additional studies demonstrate that although these children experience recurrent infections, immunoglobulin levels (IgG, IgA, IgM, and IgE) and complement components (total hemolytic complement, Clq, C3 and C3PA) are all within normal limits. Measurements of PMN random mobility and phytohemagglutinin-stimulated lymphocyte transformation were also within normal limits. These studies demonstrate a familial PMN defect limited to leukocyte chemotaxis and associated with recurrent infection and possibly redheadedness.
Bacterial Infections↗
Cystinosis in a black child.
Explore the source record for details and available documents.
Black People↗
Hair analysis for drugs of abuse XX. Incorporation and behaviors of seven methamphetamine homologs in the rat hair root.
To elucidate drug disposition in hair, the incorporation and retention behavior of 7 phenethylamines in the rat hair root were investigated: methamphetamine(MA), 3,4-methylenedioxymethamphetamine(MDMA), benzphetamine(BZP), ephedrine(EP), N,N-dimethylamphetamine(DMA), p-nitro-methamphetamine(NO2MA), and N-acetylmethamphetamine(AcMA). On day 10 after shaving the hair on the back of the rats, drug was intraperitoneally administered at a single dose of 10 mg/kg to Long Evans rats (which were male and 6 weeks of age), possessing black and white hair, and the back hair that grew was collected by plucking with hair nippers at 0.083 h (5 min), 0.25 h, 0.5 h, 1 h, 2 h, 4 h, 6 h, 9 h, 24 h, 33 h and 48 h. After washing the plucked hairs three times with 0.1% sodium dodecylsulfate, the amount of drug in each of the hair root samples was analyzed by a selected ion monitoring of gas chromatography mass spectrometry (GC-MS) analysis. The times at which the concentration of each drug in the hair root samples reached the peak concentration, ranged between 3.30 and 41.51 ng/mg. For each drug, the point of time at which the largest positive incremental change in drug concentration was seen, ranged between 5 min and 1 h, for all of the drugs except for AcMA which was hardly incorporated in the rat hair. The data showed that there are mainly 4 modes in which a drug becomes incorporated into the black hair root: rapid and prolonged incorporation (NO2MA, MDMA), rapid and short incorporation(MA, DMA), slow and prolonged incorporation(BZP, EP), slow and short incorporation, which includes hardly any incorporation (AcMA). As all seven drugs were hardly incorporated into the white hair, it was concluded that the combination of melanin and basic compounds is essential for a drug to become incorporated into hair. Our results suggest that a portion of the drugs in the hair root is accumulated in the hair shaft, and the remaining portion is redistributed outside the hair shaft. The second finding is that the concentration of drug incorporated into hair mainly depends on two processes--(1) the drug incorporation into hair and the drug retention in hair.
Animals↗
Macronutrient diet intake of the lethal yellow agouti (Ay/a) mouse.
To examine the effect of chronic endogenous melanocortin receptor (MC-R) antagonism on macronutrient diet selection, Ay/a mice that ectopically overexpress the MC-R antagonist, agouti, were fed a three-choice macronutrient diet of pure fat, carbohydrate, and protein. Ay/a mice gained more weight and consumed a greater proportion of their daily intake from fat and less from carbohydrate than wild-type littermates did. The increased fat preference was present immediately, and persisted throughout the 7-week long experiment. Protein intake was greater for Ay/a mice; however, the proportion of protein intake to total intake was similar between mouse types. Ovarian fat pads of Ay/a mice comprised a greater percentage of total body weight that that from wild-type littermates. These results suggest that endogenous inhibition of MC-Rs mediate the increased fat intake in growing mice.
Animals↗
Near infrared spectroscopy for non-invasive assessment of intracranial haemoglobin oxygenation in an in vitro model of the calf head.
An in vitro model of the calf head was used to examine the ability of near infrared spectroscopy (NIRS) to non-invasively determine oxygenation events within the calf head. The brains were removed from 16 calf skulls and replaced with oxygenated dilutions of calf blood that had the oxygen progressively decreased from PO2 > 110 mmHg to < 10 mmHg. Appropriate placement of the lighting source and sensor (optodes) was examined, as were the influences of skull thickness and overlying skin of the skull (including colour). The changes in haemaglobin oxygenation in the model calf head, as observed by NIRS, were highly correlated to PO2 changes in all 16 calf skulls examined (mean r2=0.91, range 0.71 to 0.99). There was a trend for optode positioning to achieve optimal NIRS signals over the middle of the frontal bone in a longitudinal axis and with optodes spaced 4 cm apart, but with the large variation between calf heads this was not shown to be significantly different from other sites tested. The presence of skin over the skull had a significant damping effect on the NIRS signal when compared with the bare skull (P<0.01) but it was not possible to detect a difference in this damping effect between black and white coloured skin. All but the two thickest skulls (13 and 14 mm frontal bone thickness) appeared to allow sufficiently strong NIRS signals of changes in haemoglobin oxygenation. This study showed that NIRS can be used for non-invasive study of oxygenation events within the cranial cavity of calves, and established some guidelines and limitations for its use in this species.
Animals↗
Longevity, stress response, and cancer in aging telomerase-deficient mice.
Telomere maintenance is thought to play a role in signaling cellular senescence; however, a link with organismal aging processes has not been established. The telomerase null mouse provides an opportunity to understand the effects associated with critical telomere shortening at the organismal level. We studied a variety of physiological processes in an aging cohort of mTR-/- mice. Loss of telomere function did not elicit a full spectrum of classical pathophysiological symptoms of aging. However, age-dependent telomere shortening and accompanying genetic instability were associated with shortened life span as well as a reduced capacity to respond to stresses such as wound healing and hematopoietic ablation. In addition, we found an increased incidence of spontaneous malignancies. These findings demonstrate a critical role for telomere length in the overall fitness, reserve, and well being of the aging organism.
Aging↗
Greying with age in mice: relation to expression of murine leukemia viruses.
Some strains of C57BL/10 H-2-congenic mice were found to exhibit greying with age, whereas others did not. Two patterns of greying were observed, diffuse greying beginning at 4 to 6 months of age and patterned greying beginning at 4 to 6 weeks. Strains exhibiting either greying pattern expressed high levels of infectious ecotropic and mink cell focus-inducing murine leukemia viruses (MuLV) in tests of thymus and spleen and in cultures from skin or tail biopsies, whereas nongreying strains expressed little virus until late in life. Electron microscopy demonstrated large accumulations of MuLV in grey, but not in black areas, of skin from a mouse with patterned greying. Infectious MuLV was produced spontaneously by embryos of greying, but not of nongreying, mice and pups of nongreying strains fostered on greying mothers turned grey after 3 months. These results suggest that greying with age results from melanocyte dysfunction that occurs subsequent to pre- or early postnatal infection with MuLV.
Aging↗
Melanocortin-1-receptor gene and sun sensitivity in individuals without red hair.
Susceptibility to sunburn, photoageing, and skin cancer is inversely related to an individual's ability to tan after sun exposure. We examined variants in the melanocortin-1-receptor (MC1R) gene in individuals from Ireland and the UK. We found evidence of an association between the degree of tanning after repeated sun exposure, and the number of variant alleles present. Heterozygotes were intermediate between wild-type individuals and those with two variant alleles. We suggest that MC1R gene status therefore determines sun sensitivity in people without red hair.
Adult↗