Navegando por Palavras-chave "Melanocytes"

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    Distribuição de queloide e cicatriz hipertrófica segundo fototipos de pele de Fitzpatrick
    (Sociedade Brasileira de Cirurgia Plástica, 2012-06-01) Hochman, Bernardo [UNIFESP]; Farkas, Caroline Benevides; Isoldi, Felipe Contoli; Ferrara, Soraia Francisco [UNIFESP]; Furtado, Fabianne [UNIFESP]; Ferreira, Lydia Masako [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    BACKGROUND: Keloid and hypertrophic scars have a common physiopathogenic origin and are defined as fibroproliferative scars. Fibroproliferative scars are frequent in individuals with darker skin. However, mixing of races renders it difficult to group patients with different skin tones according to morphological and static classifications (white for Caucasians; brown for individuals of Spanish descent (Hispanic/Latino); yellow for individuals of East Asian descent; and black for individuals of African descent) according to their response to sun exposure. It is known that when individuals whose ethnic origin is in colder countries move to tropical countries, they show a higher incidence of these types of scars, which mainly affect parts of the body that are more exposed to the sun. A correlation between fibroproliferative scars and Fitzpatrick phototype, a dynamic classification based on the skin's response to sun exposure, would contribute to an understanding of the pathophysiology of these scars. The aim of this study is to investigate the distribution of fibroproliferative scars according to Fitzpatrick phototypes. METHODS: We classified patients' fibroproliferative scars according to the Muir classification as Long-Term Evolution (keloid scars), Short-Term Evolution (hypertrophic scars), and Intermediate Group (mixed scars), while their skin types were grouped according to the Fitzpatrick classification. RESULTS: Fitzpatrick phototype III and mixed scars were predominant among the patients analyzed (p = 0.001). A correlation (p = 0.025) was observed between fibroproliferative scars and Fitzpatrick phototypes; the higher the phototype, the higher the tendency to develop keloid and mixed scar tissue. CONCLUSIONS: Fitzpatrick skin phototypes proved to be an efficient method to study keloid and hypertrophic scars.
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    Endothelial nitric oxide synthase uncoupling as a key mediator of melanocyte malignant transformation associated with sustained stress conditions
    (Elsevier B.V., 2011-05-15) Melo, Fabiana Henriques Machado de [UNIFESP]; Molognoni, Fernanda [UNIFESP]; Morais, Alice Santana [UNIFESP]; Toricelli, Mariana [UNIFESP]; Mouro, Margaret Gori [UNIFESP]; Higa, Elisa Mieko Suemitsu [UNIFESP]; Lopes, Jose Daniel [UNIFESP]; Jasiulionis, Miriam Galvonas [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Melanoma cell lines and cells corresponding to premalignant melanocytes were established by our group after subjecting a nontumorigenic murine melanocyte lineage, melan-a, to sequential cycles of anchorage blockade. Previous results showed that in melan-a cells the superoxide level increases after such procedure. Superoxide production during melanocyte de-adhesion was inhibited by L-sepiapterin, the precursor of eNOS cofactor BH(4), and increased by the inhibitor of BH(4) synthesis, DAHP, hence indicating a partial uncoupling state of eNOS. the eNOS uncoupling seems to be maintained in cells derived from melan-a, because they present decreased nitric oxide and increased superoxide levels. the inhibition of superoxide production in Tm5 melanoma cells with L-sepiapterin reinforces their eNOS-uncoupled state. the maintenance of oxidative stress seems to be important in melanoma apoptosis resistance because Mn(III)TBAP, a superoxide scavenger, or L-sepiapterin renders Tm5 cells more sensitive to anoikis and chemotherapy. More importantly, eNOS uncoupling seems to play a pivotal role in melanocyte malignant transformation induced by sustained anchorage impediment, because no malignant transformation was observed when L-NAME-treated melanocytes were subjected to sequential cycles of de-adhesion. Our results show that uncoupled eNOS contributes to superoxide production during melanocyte anchorage impediment, contributing to anoikis resistance and malignant transformation. (C) 2011 Elsevier Inc. All rights reserved.
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    Melanocitoma do nervo óptico
    (Sociedade Brasileira de Oftalmologia, 2008-12-01) Gouveia, Enéias Bezerra; Morales, Maira Saad De Ávila [UNIFESP]; Centro Médico Avimed; Universidade Federal de São Paulo (UNIFESP)
    Melanocytoma of the optic disc is a well known variant of melanocytic nevus that usually occurs as a deeply pigmented lesion on the head of the optic disc. Historically, this tumor has often been confused with malignant melanoma. Histopathologically, it is composed of deeply pigmented round oval cells with abundant cytoplasm and small, round, bland nuclei. Melanocytomas is a benign, stationary tumors, with almost no propensity to undergo malignant transformation. Most cases that occur on the optic disc are visually asymptomatic, but they can cause an afferent pupillary and visual field defects. Importantly, it can exhibit malignant transformation into melanoma in 1 to 2% of the cases. The affected patients should have periodic follow up.
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    Modificações em marcas epigenéticas em histonas ao longo da gênese do melanoma
    (Universidade Federal de São Paulo (UNIFESP), 2011) Meliso, Fabiana Marcelino [UNIFESP]; Jasiulionis, Miriam Galvonas [UNIFESP]
    Entre os principais transtornos mundiais, o cancer permanece como a segunda doenca responsavel pelo maior numero de mortes no mundo e o melanoma e, cada vez mais, um dos tipos mais preocupantes de tumor. Os tumores, como amplamente estudado, estao relacionados a fatores geneticos e epigeneticos, entretanto, ate o momento, nao esta claro quais sao os fatores que levam ao estabelecimento de padroes epigeneticos aberrantes associados tanto ao inicio quanto a progressao tumoral. Recentes estudos tem demonstrado que alteracoes no microambiente celular, assim como o estresse oxidativo, sao importantes fatores que levam ao estabelecimento de caracteristicas neoplasicas. Metilacao de DNA e modificacoes pos-traducionais em histonas sao os mecanismos epigeneticos mais estudados. Embora haja estudos sobre metilacao de DNA aberrante em melanomas, ainda sao escassos os estudos sobre marcas em histonas nestes tumores. Nesse sentido, utilizando um modelo murino de transformacao maligna de melanocitos associado a condicoes sustentadas de estresse, esse trabalho teve por objetivo identificar padroes epigeneticos aberrantes associados a diferentes fases da genese do melanoma. Foram observadas variacoes em marcas de histonas relacionadas a ativacao ou repressao genica nas primeiras etapas e ao longo da progressao maligna, com indicios de cromatina aberta nos estagios intermediarios da transformacao. Da mesma forma, identificamos alteracoes em componentes da maquinaria epigenetica ao longo da transformacao maligna dos melanocitos. Alem disso, dados ainda preliminares indicam associacao diferencial de sequencias de DNA a desacetilase de histonas Sirt1 apos submeter os melanocitos a situacao de estresse sustentado, o que pode indicar um papel de Sirt1 no estabelecimento de padroes epigeneticos aberrantes. Finalmente, esse trabalho mostra mudancas dinamicas tanto em componentes da maquinaria quanto em marcas epigeneticas ao longo da genese do melanoma e ainda sugere reprogramacao epigenetica e aquisicao de caracteristicas de pluripotencia nos estagios que precedem a aquisicao do fenotipo maligno pelos melanocitos