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Melanin Pigment (melanin + pigment)
Selected AbstractsEffects of Melanogenesis-Inducing Nitric Oxide and Histamine on the Production of Eumelanin and Pheomelanin in Cultured Human MelanocytesPIGMENT CELL & MELANOMA RESEARCH, Issue 1 2003Michael W. Lassalle Melanin pigments produced in human melanocytes are classified into two categories; black coloured eumelanin and reddish-yellow pheomelanin. Stimulation of melanocytes with ,-melanocyte-stimulating hormone (,-MSH), one of several melanogenic factors, has been reported to enhance eumelanogenesis to a greater degree than pheomelanogenesis, which contributes to hyperpigmentation in skin. Nitric oxide (NO) and histamine are also melanogenesis-stimulating factors that are released from cells surrounding melanocytes following ultraviolet (UV) irradiation. In this study, the effects of NO and histamine on the ratio of eumelanin and pheomelanin were examined in human melanocytes, and then compared with that of ,-MSH. The amounts of eumelanin and pheomelanin were quantified using high-performance liquid chromatography analysis after oxidation and hydrolysis of melanin. Melanogenesis was induced by the addition of ,-MSH, NO, or histamine to melanocytes. The amount of eumelanin production significantly increased with independent stimulation by these melanogenic factors, especially histamine, while that of pheomelanin significantly increased with ,-MSH and NO, but only slightly with histamine. As a result, the ratio of eumelanin and pheomelanin increased significantly with the addition of NO or histamine. These results suggest that NO and histamine, as in the case of ,-MSH, may contribute to UV-induced hyperpigmentation by enhancing eumelanogenesis. [source] Histologic and Ultrastructural Analysis of Ultraviolet B Laser and Light Source Treatment of Leukoderma in Striae DistensaeDERMATOLOGIC SURGERY, Issue 4 2005David J. Goldberg MD Background. Lasers and light sources emitting ultraviolet B (UVB) irradiation have been shown to repigment striae distensae. Objective. The purpose of this study was to analyze the histologic and ultrastuctural changes seen after UVB laser, or light source,induced repigmentation of striae distensae. Methods. Ten subjects with hypopigmented striae were selected. Five subjects were treated with an XeCl excimer UVB laser, and five subjects were treated with a UVB light device. Six months after the final treatment, the biopsies were evaluated for both standard and electron microscopic changes in melanocytes. Results. Analyses of biopsied skin after treatment with both the UVB laser and light source showed increased melanin content, hypertrophy of melanocytes, and an increase in the number of melanocytes in all patients. Conclusions. Repigmentation of striae distensae with either a UVB laser or light source is due to an increase in melanin pigment, hypertrophy of melanocytes, and an increase in melanocytes. DAVID J. GOLDBERG, MD, ELLEN S. MARMUR, MD, CHRYSALINE SCHMULTS, MD, MUSSARRAT HUSSAIN, MD, AND ROBERT PHELPS, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source] Melanin-associated pigmented lesions of the oral mucosa: presentation, differential diagnosis, and treatmentDERMATOLOGIC THERAPY, Issue 3 2010Susan Müller ABSTRACT Intraoral pigmentation is quite common and has numerous etiologies, ranging from exogenous to physiological to neoplastic. Many pigmented lesions of the oral cavity are associated with melanin pigment. The differential diagnosis of mucosal pigmented lesions includes hematomas, varices, and petechiae which may appear to be pigmented. Unlike cutaneous melanomas, oral melanomas are diagnosed late and have a poor prognosis regardless of depth of invasion. As such, the clinical presentation and treatment of intraoral melanoma will be discussed. Developing a differential diagnosis is imperative for a clinician faced with these lesions in order to appropriately treat the patient. This article will focus on the most common oral melanocytic lesions, along with mimics. [source] Effusion cytomorphology and immunocytochemistry of malignant melanoma: Five cases of melanotic melanoma and one case of amelanotic melanomaDIAGNOSTIC CYTOPATHOLOGY, Issue 7 2009I.A.C., Katsuhide Ikeda C.T. Abstract Effusion cytological analyses of amelanotic malignant melanoma (AMM) are very rare and no concise description of AMM related cytomorphologic features using effusion have been reported. Here, we report the cytomorphological, immunohistochemical, and immunocytochemical findings in the effusion cytology of six cases of malignant melanoma (MM), one case of AMM, and five cases of melanotic malignant melanoma. Papanicolaou-stained smears exhibited conspicuous nucleoli, multinucleation, and cytoplasmic vacuolization in all of the MM cases. In addition, the AMM case displayed numerous mitotic figures and intranuclear cytoplasmic inclusions. With regard to the immunohistochemistry findings, all six cases of melanoma were positive for Melan-A/MART-1, HBME-1, and S-100. In the immunohistochemistry analyses, five of six cases of melanoma were positive for WT-1, as was the AMM specimen. Furthermore, because the effusion analysis of malignant mesothelioma proved positive for WT-1, it should be noted that WT-1 effusion analysis is not an appropriate means to distinguish between MM and malignant mesothelioma. We suggest that it is important to recognize cytomorphologic characteristics, such as melanin pigment, conspicuous nucleoli, multinucleation, and cytoplasmic vacuolization, and to choose appropriate antibodies for the correct diagnosis of MM in effusion. Diagn. Cytopathol., 2009. © 2009 Wiley-Liss, Inc. [source] Diagnosis of melanoma aspirates on ThinPrep®: The University of Michigan experienceDIAGNOSTIC CYTOPATHOLOGY, Issue 5 2002Güliz Akdas Barkan M.D. Abstract The purpose of this study was to compare the cytologic features of melanoma fine-needle aspirates (FNAs) prepared by ThinPrep® (TP) with those in conventional smears (CS) and to identify any diagnostic pitfalls. Fifty-one aspirates diagnosed as melanoma were obtained, 36 of which were prepared by both TP and CS. The preparations were evaluated for cellularity, cell aggregates, cellular appearance, melanin pigment, cytoplasmic, and nuclear features. Categorical data were analyzed by the chi-square test and continuous data by the Wilcoxin-signed rank test. Correlation was determined by Spearman's test for bivariate correlations (rho). Good correlation between the two methods was identified for the following features: cellularity, cell type, bi/multinucleated cells, cytoplasmic features, NC ratio, and presence of macronucleoli. TP exhibits coarser chromatin compared to CS (P = 0.005). Six of 36 CS contained large cellular groups; none of the TP contained them (P = 0.018). Twenty-five of 36 CS contained intranuclear inclusions as opposed to 12/36 TP (P < 0.001). The number of inclusions was significantly reduced on TP. The amount of intracellular melanin was the same with both techniques. Background melanin was markedly reduced on TP except when either trapped by fibrin or attached to cellular clusters (P = 0.006). Background blood was also markedly reduced on TP (P < 0.005). In summary, the cytological features of TP and CS for FNA evaluation of melanoma correlate well; however, one needs to be aware of the cytologic alterations introduced by TP. TP is a sufficient preparation method in the diagnosis of melanoma FNA aspirates when performed by clinicians. It is also a useful adjunct in bloody or low-cellular aspirates, where it tends to reduce the background blood and concentrate the cells. Diagn. Cytopathol. 2002;26:334,339. © 2002 Wiley-Liss, Inc. [source] Melanism in a larval Lepidoptera: repeatability and heritability of a dynamic traitECOLOGICAL ENTOMOLOGY, Issue 2 2006Kwang Pum Lee Abstract., 1.,Although it is well established that the deposition of melanin pigment in the cuticle of larval Lepidoptera is influenced by both environmental and genetic factors, few studies have examined intra-individual regional variation in the degree of melanism or the ontogenetic dynamics of this trait. Here, heritable and density-dependent effects on within-individual and stage-specific variation in melanism were examined in caterpillars of the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval). 2.,Using quantitative spectrometric methods, it is shown that cuticular melanism changes dramatically within larval stadia, showing the highest and lowest levels of melanism early (first day) and late (final day) in each larval stadium respectively. However, solitary-reared caterpillars were significantly paler than those reared gregariously at all stages of development and maintained greater levels of variation in melanism. This variation in melanism was repeatable and exhibited a significant heritable component (narrow sense heritability based on offspring,parent regressions: h2 = 0.18,0.30). 3.,The degree of melanism was correlated negatively with larval body weight in solitary caterpillars, but not gregarious ones. Melanism also varied spatially, with the lateral longitudinal band being consistently darker than the dorsal or dorso-lateral bands. Crowd-rearing increased melanism in all regions of larval cuticle, but the extent of crowding-induced melanism was more pronounced in the dorsal and dorso-lateral bands than in the lateral one. 4.,These results indicate that although cuticular melanism is a highly dynamic trait, ontogenetic changes in relative cuticular melanism are both predictable and repeatable within individuals and genotypes. This has implications for our understanding of the evolution of melanism and for applying artificial selection on the basis of colour. [source] Application of computerized image analysis in pigmentary skin diseasesINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2001Eun-So Lee MD Background Melanocyte number and the amount of melanin pigment are related to diagnosis and treatment of pigmentary skin diseases. Various histologic methods are used, such as Fontana-Masson stain for melanin pigment or immunohistochemical stain for melanocytes. Recently, computerized image analysis has been applied to many fields to avoid interobserver bias. In this study, we applied a computerized image analysis to assess the melanin content and melanocyte density of human epidermis. Methods We evaluated the skin biopsy specimens (paraffin blocks) from normal human skin (33 ± 6.6, n = 11) and diseased skins; vitiligo (32 ± 10.0, n = 8), melasma (35 ± 8.6, n = 11), and lentigo senilis (40 ± 7.2, n = 11) (mean age ± SD). Each specimen was stained with Fontana,Masson for melanin pigments and immunohistochemical method for melanocytes. Quantitative analysis of melanin pigment and melanocyte number (density) were investigated through two methods: (1) two dermatologists measured the visual scales; and (2) computerized image analysis was used to measure melanin content indices (MCI). The data were evaluated using one-way anova. Results The visual scale of the Fontana,Masson stain was the highest for lentigo senilis (3.8 ± 0.40), followed by melasma (2.6 ± 0.67), normal skin (1.8 ± 0.60) and vitiligo (0) (P < 0.05). These findings were consistent with objective measurements made by computerized image analysis. MCI values were 120.3 ± 20.74 for lentigo senilis, 81.1 ± 19.27 for melasma, 45.5 ± 16.92 for normal skin, and 0.3 ± 0.30 for vitiligo in decreasing order (P < 0.05). MC/1E (melanocyte number per 1 mm epidermis) was about two fold larger in lentigo senilis (18.1 ± 8.92) than melasma (9.7 ± 2.40) or normal skin (9.3 ± 2.67) (P < 0.05). MC/1B (melanocyte number per 1 mm basal layer) was about 1.5 fold higher in lentigo senilis (13.5 ± 4.17), compared to normal skin (9.0 ± 3.55) (P < 0.05). Melasma showed increased melanocyte numbers compared to normal skin, but it was not statistically significant (P > 0.05). Conclusion We believe this computerized image analysis could be useful tool for diagnosis and comparison of interval changes in pigmentary diseases like melasma or lentigo senilis by quantifying melanin pigments or melanocytes in skin biopsy specimens. [source] Clear cell sarcoma of soft tissue: diagnostic utility of fluorescence in situ hybridization and reverse transcriptase polymerase chain reactionJOURNAL OF CUTANEOUS PATHOLOGY, Issue 4 2008Choladda V. Curry A 7-year-old girl presented with pain and progressive swelling on the left plantar surface. Biopsy of a 2.5 cm mass showed nests of large round to oval neoplastic cells with abundant amphophilic to clear cytoplasm, prominent nucleoli and high mitotic activity. Occasional cells showed spindled morphology. Infrequent melanin pigment was present. Melanocytic markers (HMB45, S-100) were diffusely positive. A diagnosis of clear cell sarcoma of soft tissue (CCSS) was made, and the mass was re-excised with negative margins. 28 months later, a 1.0 cm pulmonary nodule was identified and wedge excision showed metastatic CCSS. Cytogenetics showed a complex karyotype (unbalanced translocation der(12;14)(q10;q10), additional chromosome 22 material of unknown origin). Although the CCSS translocation t(12;22)(q13;q12) was not identified, EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH). Reverse transcription polymerase chain reaction (RT-PCR) showed an EWS-ATF1 fusion transcript, confirmed by direct sequencing. CCSS requires differentiation from malignant melanoma, because of overlapping clinical presentations, sites of involvement, histomorphology, immunocytochemical profiles and ultrastructure. In many circumstances, definitive diagnosis is only possible with confirmation of the CCSS-defining translocation. [source] Clear Cell Sarcoma of Soft Tissue with Cytogenetic and Molecular AnalysesJOURNAL OF CUTANEOUS PATHOLOGY, Issue 1 2006C. Vejabhuti A 7-year-old girl presented with pain and progressive swelling on the left plantar surface. Biopsy of a 2.5 cm mass demonstrated nests of large oval tumor cells with high nuclear-to-cytoplasm ratio, amphophilic to clear cytoplasm, prominent nucleoli, and brisk mitotic activity. Occasional cells showed spindled morphology. Infrequent melanin pigment was present. Melanocytic markers (HMB45, S-100) were diffusely positive. A diagnosis of clear cell sarcoma of soft tissue (CCSS) was made, and the tumor was re-excision with negative margins. 28 months later, a 1.0 cm pulmonary nodule was identified and showed CCSS. Cytogenetics demonstrated a complex karyotype (unbalanced translocation der(12;14)(p10;q10), additional chromosome 22 material of unknown origin). Although the CCSS translocation t(12;22)(q13;q12) was not identified, EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH). RT-PCR demonstrated an EWS-ATF1 fusion transcript, confirmed by direct sequencing. CCSS requires differentiation from malignant melanoma, due to overlapping clinical presentations, sites of involvement, histomorphology, immunocytochemical profiles, and ultrastructure. In many circumstances, definitive diagnosis is only possible with confirmation of the CCSS tumor-defining translocation. [source] The Role of P-75 NGF-R in the Diagnosis of Desmoplastic MelanomaJOURNAL OF CUTANEOUS PATHOLOGY, Issue 1 2005S. Ghosn The histologic diagnosis of desmoplastic melanoma is challenging, particularly when the overlying junctional component is absent and when the spindle cells lack melanin pigment. In these instances, the importance of immunohistochemistry cannot be overemphasized. S-100 protein, with a sensitivity approaching 90%, is the primary immunohistochemical stain used for this purpose. HMB-45, although a more specific marker for melanocytes, is often negative in these cases. A marker of schwannian differentiation, p-75 NGF-R has been shown to be a useful confirmatory marker for desmoplastic and neurotropic melanoma, with staining intensity comparable to or better than S-100 protein. We report two cases of desmoplastic melanoma which stained focally and weakly with S-100 protein in comparison with the stronger staining of p-75 NGF-R. In both cases, S-100 staining could have been missed or interpreted as non-confirmatory, thus misguiding the diagnosis. We therefore suggest that p-75 NGF-R be a complementary marker to S-100 protein in differentiating desmoplastic melanoma from other non-neural crest-derived spindle cell tumors. [source] Genetics of human iris colour and patternsPIGMENT CELL & MELANOMA RESEARCH, Issue 5 2009Richard A. Sturm Summary The presence of melanin pigment within the iris is responsible for the visual impression of human eye colouration with complex patterns also evident in this tissue, including Fuchs' crypts, nevi, Wolfflin nodules and contraction furrows. The genetic basis underlying the determination and inheritance of these traits has been the subject of debate and research from the very beginning of quantitative trait studies in humans. Although segregation of blue-brown eye colour has been described using a simple Mendelian dominant-recessive gene model this is too simplistic, and a new molecular genetic perspective is needed to fully understand the biological complexities of this process as a polygenic trait. Nevertheless, it has been estimated that 74% of the variance in human eye colour can be explained by one interval on chromosome 15 that contains the OCA2 gene. Fine mapping of this region has identified a single base change rs12913832 T/C within intron 86 of the upstream HERC2 locus that explains almost all of this association with blue-brown eye colour. A model is presented whereby this SNP, serving as a target site for the SWI/SNF family member HLTF, acts as part of a highly evolutionary conserved regulatory element required for OCA2 gene activation through chromatin remodelling. Major candidate genes possibly effecting iris patterns are also discussed, including MITF and PAX6. [source] The Pigmentation of Human Iris Influences the Uptake and Storing of ZincPIGMENT CELL & MELANOMA RESEARCH, Issue 5 2004Despina Kokkinou Age-related macular degeneration (AMD) is more prevalent among the elderly Caucasians than in Africans. A significant association between light iris colour, fundus pigmentation and incidence of AMD is reported, suggesting a possible correlation with melanin pigment. Zinc is known to bind to melanin in pigmented tissues and to enhance antioxidant capacity by function as a cofactor or gene expression factor of antioxidant enzymes in the eye. In this in vitro study, we investigated the uptake and storage of zinc in human irides. Irides of blue and brown human eyes were used. The number of melanocytes was measured. Tissues without any treatment served as controls. The irides were incubated with 100 ,M zinc chloride in culture medium for 24 h. Specimens of the tissues were stored for the uptake examination. The remained pieces were further incubated for 3 and 7 d to investigate the storage of zinc. The concentration of zinc was measured by inductively coupled plasma mass spectrometry (ICP-MS). Melanocytes count was significantly higher in the brown tissues (P < 0.0001). Zinc concentration of blue coloured irides after 24 h zinc treatment was close to the controls. We did not observe any significant storing. In contrast, the concentration of zinc in brown irides was significantly increased after 24 h (P , 0.01) and remained at a high level for 7 d. The uptake of zinc is likely dependent on the amount of pigmentation in human iris. Therefore, we assume that in patients suffering from AMD the degree of pigmentation of the irides and eventually fundi should be under consideration when the patients are treated with zinc supplementation. [source] Six novel mutations of the ADAR1 gene in patients with dyschromatosis symmetrica hereditaria: Histological observation and comparison of genotypes and clinical phenotypesTHE JOURNAL OF DERMATOLOGY, Issue 7 2008Taisuke KONDO ABSTRACT Dyschromatosis symmetrica hereditaria (DSH), is a pigmentary genodermatosis of autosomal dominant inheritance. Since we clarified that the disease is caused by a mutation of the adenosine deaminase acting on the RNA 1 gene (ADAR1) in 2003, the molecular pathogenesis of a peculiar clinical feature of the disease has been expected to be clarified. We examined five familial cases and one sporadic case of Japanese families with DSH. The mutation analyses were done with single-strand conformation polymorphism/heteroduplex (SSCP/HD) analysis and direct sequencing of ADAR1. The DNA analysis of each patient revealed one missense mutation (p.F1091S), two nonsense mutations (p.C893X, p.S581X) and three frame-shift mutations (p.E498fsX517, p.F1091fsX1092, p.L855fsX856). Visual and electron microscopic findings showed abundant melanin pigment deposited all over the basal layer, and enlarged melanocytes with long dendrites located in the pigmented lesions with small or immature melanosomes scattered sparsely in the cytoplasm, but in the adjacent keratinocytes many small melanosomes were singly dispersed or aggregated. The hypopigmented areas showed little melanin deposition and reduced numbers of melanocytes in which much degenerative cytoplasmic vacuole formation could be observed by electron microscopy. Herein, we report six cases of DSH with six novel mutations. The variety of their clinical phenotypes even in the pedigree may suggest the presence of factors other than the ADAR1 gene influencing the extent of the clinical skin lesion. Microscopic findings suggest that the clinical appearance must have developed directly by melanocyte variations mainly induced by the ADAR1 gene mutations. [source] Cyclosporine treatment of RPE allografts in the rabbit subretinal spaceACTA OPHTHALMOLOGICA, Issue 2 2000Sven Crafoord ABSTRACT. Purpose: To determine the effects of systemic cyclosporine A (CsA) on the survival of retinal pigment epithelial (RPE) allografts in the subretinal space in an animal model using atraumatic transplantation surgery. Methods: Following pars plana vitrectomy, an RPE cell suspension from brown rabbits was injected with a glass micropipette into the subretinal space of 39 albino rabbits. For immunosuppression, 22 rabbits were given an injection of CsA, 20 mg daily intramuscularly, 17 rabbits with RPE grafts were controls. The grafts were monitored by biomicroscopy, color fundus photography, and fluorescein angiography. Rabbits were sacrificed at 1, 3 and 6 months, respectively, and the eyes processed for light and electron microscopy including immunohistochemistry. Results: After three months, the transplanted RPE cells, in both the CsA group and the controls, formed a monolayer in the subretinal space. Although a few macrophages were encountered, there was no massive cellular infiltration and the photoreceptor layer was well preserved. After six months, however, there was a disruption of grafted RPE cells in both groups, characterized by dispersion of melanin pigment in the subretinal space, and invasion of macrophages with focal photoreceptor damage but no infiltration of lymphocytes in the retina or choroid. No significant differences between the CsA treated and the control eyes were discernible. Conclusion: Although the subretinal space has been considered an immunologically privileged site, we found that the survival of RPE allografts was limited. CsA did not prevent RPE allograft destruction in the subretinal space. The transplant seems to be disrupted either by immunological mechanisms that are not inhibited by CsA, or by nonimmunologic events. [source] ,-MSH and cAMP signalling in normal human melanocytesEXPERIMENTAL DERMATOLOGY, Issue 9 2004R. Buscà Melanocytes are neural crest-derived skin cells specialized in the synthesis of melanin pigments responsible, in human, for skin and hair colour. The pro-opiomelanocortin peptide, ,-MSH is a strong melanogenic agent secreted by keratinocytes following UV radiation. ,-MSH through the binding to the MC1R and activation of the cyclic AMP pathway plays a pivotal role in melanocyte differentiation and in the regulation of skin pigmentation. During the last few years, we have elucidated the molecular events linking the cAMP pathway to melanogenesis upregulation. This cascade involves the activation of protein kinase A and CREB transcription factor, leading to the upregulation of the expression of microphthalmia-associated transcription factor (MITF). MITF binds and activates the melanogenic gene promoters thereby increasing their expression, which results in an increased melanin synthesis. Beyond this simplified scheme, other intracellular signalling pathways are regulated by cAMP and participate to the regulation of melanocyte differentiation. Indeed, cAMP inhibits the phosphatidyl inositol 3-kinase pathway, leading to the inhibition of AKT and to the activation of GSK3,. This kinase phosphorylates MITF and allows its binding to the target sequence. Such pathways are involved in the upregulation of melanogenesis. ,-MSH and cAMP signalling also regulate melanocyte dendricity, and melanosome transport through the inhibition of the Rho GTPase cascade that function downstream the PI3 kinase. It should be also mentioned that cAMP activates the ERK pathway through a melanocyte-specific pathway involving Ras and B-Raf. The activation of ERK and RSK1 leads to the phosphorylation of MITF and target MITF to the proteasome degradation pathway. Interestingly, several proteins involved in melanocyte differentiation by ,-MSH (MC1R, PI3K, B-Raf and MITF) have also been implicated in the development of melanoma, suggesting that the cAMP pathway could influence melanocyte transformation. [source] Application of computerized image analysis in pigmentary skin diseasesINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2001Eun-So Lee MD Background Melanocyte number and the amount of melanin pigment are related to diagnosis and treatment of pigmentary skin diseases. Various histologic methods are used, such as Fontana-Masson stain for melanin pigment or immunohistochemical stain for melanocytes. Recently, computerized image analysis has been applied to many fields to avoid interobserver bias. In this study, we applied a computerized image analysis to assess the melanin content and melanocyte density of human epidermis. Methods We evaluated the skin biopsy specimens (paraffin blocks) from normal human skin (33 ± 6.6, n = 11) and diseased skins; vitiligo (32 ± 10.0, n = 8), melasma (35 ± 8.6, n = 11), and lentigo senilis (40 ± 7.2, n = 11) (mean age ± SD). Each specimen was stained with Fontana,Masson for melanin pigments and immunohistochemical method for melanocytes. Quantitative analysis of melanin pigment and melanocyte number (density) were investigated through two methods: (1) two dermatologists measured the visual scales; and (2) computerized image analysis was used to measure melanin content indices (MCI). The data were evaluated using one-way anova. Results The visual scale of the Fontana,Masson stain was the highest for lentigo senilis (3.8 ± 0.40), followed by melasma (2.6 ± 0.67), normal skin (1.8 ± 0.60) and vitiligo (0) (P < 0.05). These findings were consistent with objective measurements made by computerized image analysis. MCI values were 120.3 ± 20.74 for lentigo senilis, 81.1 ± 19.27 for melasma, 45.5 ± 16.92 for normal skin, and 0.3 ± 0.30 for vitiligo in decreasing order (P < 0.05). MC/1E (melanocyte number per 1 mm epidermis) was about two fold larger in lentigo senilis (18.1 ± 8.92) than melasma (9.7 ± 2.40) or normal skin (9.3 ± 2.67) (P < 0.05). MC/1B (melanocyte number per 1 mm basal layer) was about 1.5 fold higher in lentigo senilis (13.5 ± 4.17), compared to normal skin (9.0 ± 3.55) (P < 0.05). Melasma showed increased melanocyte numbers compared to normal skin, but it was not statistically significant (P > 0.05). Conclusion We believe this computerized image analysis could be useful tool for diagnosis and comparison of interval changes in pigmentary diseases like melasma or lentigo senilis by quantifying melanin pigments or melanocytes in skin biopsy specimens. [source] Red-winged blackbirds Agelaius phoeniceus use carotenoid and melanin pigments to color their epauletsJOURNAL OF AVIAN BIOLOGY, Issue 6 2004Kevin J. McGraw Over the past three decades, the red-winged blackbird Agelaius phoeniceus has served as a model species for studies of sexual selection and the evolution of ornamental traits. Particular attention has been paid to the role of the colorful red-and-yellow epaulets that are striking in males but reduced in females and juveniles. It has been assumed that carotenoid pigments bestow the brilliant red and yellow colors on epaulet feathers, but this has never been tested biochemically. Here, we use high-performance liquid chromatography (HPLC) to describe the pigments present in these colorful feathers. Two red ketocarotenoids (astaxanthin and canthaxanthin) are responsible for the bright red hue of epaulets. Two yellow dietary precursors pigments (lutein and zeaxanthin) are also present in moderately high concentrations in red feathers. After extracting carotenoids, however, red feathers remained deep brown in color. HPLC tests show that melanin pigments (primarily eumelanin) are also found in the red-pigmented barbules of epaulet feathers, at an approximately equal concentration to carotenoids. This appears to be an uncommon feature of carotenoid-based ornamental plumage in birds, as was shown by comparable analyses of melanin in the yellow feathers of male American goldfinches Carduelis tristis and the red feathers of northern cardinals Cardinalis cardinalis, in which we detected virtually no melanins. Furthermore, the yellow bordering feathers of male epaulets are devoid of carotenoids (except when tinged with a carotenoid-derived pink coloration on occasion) and instead are comprised of a high concentration of primarily phaeomelanin pigments. The dual pigment composition of red epaulet feathers and the melanin-only basis for yellow coloration may have important implications for the honesty-reinforcing mechanisms underlying ornamental epaulets in red-winged blackbirds, and shed light on the difficulties researchers have had to date in characterizing the signaling function of this trait. As in several other birds, the melanic nature of feathers may explain why epaulets are used largely to settle aggressive contests rather than to attract mates. [source] Increased dopamine and its metabolites in SH-SY5Y neuroblastoma cells that express tyrosinaseJOURNAL OF NEUROCHEMISTRY, Issue 2 2003Takafumi Hasegawa Abstract Oxidized metabolites of dopamine, known as dopamine quinone derivatives, are thought to play a pivotal role in the degeneration of dopaminergic neurons. Although such quinone derivatives are usually produced via the autoxidation of catecholamines, tyrosinase, which is a key enzyme in melanin biosynthesis via the production of DOPA and subsequent molecules, may potentially accelerate the induction of catecholamine quinone derivatives by its oxidase activity. In the present study, we developed neuronal cell lines in which the expression of human tyrosinase was inducible. Overexpression of tyrosinase in cultured cell lines resulted in (i) increased intracellular dopamine content; (ii) induction of oxidase activity not only for DOPA but also for dopamine; (iii) formation of melanin pigments in cell soma; and (iv) increased intracellular reactive oxygen species. Interestingly, the expressed tyrosinase protein was initially distributed in the entire cytoplasm and then accumulated to form catecholamine-positive granular structures by 3 days after the induction. The granular structures consisted of numerous rounded, dark bodies of melanin pigments and were largely coincident with the distribution of lysosomes. This cellular model that exhibits increased dopamine production will provide a useful tool for detailed analyses of the potentially noxious effects of oxidized catecholamine metabolites. [source] An update on the honesty of melanin-based color signals in birdsPIGMENT CELL & MELANOMA RESEARCH, Issue 2 2008Kevin J. McGraw Summary The control mechanisms and information content of melanin-based color signals in birds have generated much recent interest and controversy among evolutionary biologists. Initial experimental studies on this topic manipulated coarse metrics of an individual's condition (i.e. food intake, disease state) and failed to detect significant condition-dependence of melanin ornament expression. However, three new lines of research appear profitable and target specific factors associated with the production of melanin pigments. These include the role of (i) metals, (ii) amino acids, and (iii) testosterone and social interactions in shaping the extent and intensity of melanin-colored plumage patches. Here, I review recent studies of and evidence for these honesty-reinforcing mechanisms. [source] | |||||||||||||