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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Experimental dermatology 13 (2004), S. 0 
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: In the development of congenital nevi, how nevus cells migrate in the dermis remains unclear. As shown in an earlier study designed to investigate Unna's Abtropfung hypothesis, dermal invasion does not occur when nevus cells are seeded on epidermal reconstructs. In melanoma, the decrease of E-cadherin expression is associated with the dermal invasion of melanoma cells. Objective: To study the expression of E-cadherin in dermal-cultured nevus cells from congenital nevi and its relevance to explain the absence of dermal invasion noted in epidermis reconstructed with cultured nevus cells. Methods: Comparison of the immunohistochemical expression pattern of E-cadherin in congenital nevi in vivo and after culture in monolayers and in a three-dimensional system. Results: E-cadherin was not expressed in vivo by dermal nevus cells, either isolated or in nests. However, in monolayer cultures, dermal nevus cells expressed E-cadherin. When these cells were used in reconstructed epidermis, nevus cells did not invade the dermis and they expressed E-cadherin when isolated and just weakly or not when grouped in junctional nests. Conclusions: The absence of dermal invasion of nevus cells could be due to the expression of E-cadherin in these cells in reconstructed epidermis. Our experiments suggest, a restoration of the control of keratinocytes, that nevus cells escape in the dermal compartment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Experimental dermatology 14 (2005), S. 0 
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract:  The incidence rate of melanoma is higher in fair-skinned than in dark-skinned individuals. In negroid skin there is more eumelanin which is present in all skin layers and fewer polyunsaturated fatty acids (PUFA) than in caucasoid skin. The western diet, which is rich in omega–6 polyunsaturated fatty acids, is associated with more proneness to cancer including cutaneous melanoma. To study the respective influence of omega-6 PUFA and low phototype melanocytes on redox status -basal and following UV irradiation-, we used epidermal reconstructs. The addition of polyunsaturated fatty acids as well as the presence of low phototype melanocytes affected basal status similarly except for catalase activity, which decreased significantly in polyunsaturated fatty acid-supplemented reconstructs. Following UV, polyunsaturated fatty acids and low phototype melanocytes increased lipid and protein oxidative damage without affecting direct DNA damage. However, polyunsaturated fatty acids increased epidermal apoptosis whereas low phototype melanocytes decreased it. Since our data suggest that an omega-6 PUFA rich-diet may increase oxidative damage in melanocytes without inducing apoptosis, the long-term net outcome could be cumulated mutations and an increased risk of skin cancer, especially melanoma.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Journal of cutaneous pathology 31 (2004), S. 0 
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Senile lentigo (SL) is a common component of photoaged skin. It is characterized by hyperpigmented macules which affect chronically irradiated skin mostly after 50 years of age. This study was undertaken to assess the basic morphology of SL on dorsum of hands.Methods:  A systematic comparison between lesional vs. perilesional skin using immunohistochemistry and electron microscopy was done to detect precursor lesions of SL and to determine whether melanocytes or keratinocytes were first affected in the evolution of lesions.Results:  In 12 cases studied, the main findings show that clusters of perilesional keratinocytes accumulate melanin in large melanosomial complexes, and that melanocytes counts are increased respective to total length of section in lesional skin, but the increment is probably due to the development of characteristic epidermal rete ridges. Melanocytes had overall a normal ultrastructure, with mostly quiescent features in perilesional skin and melanosomial transport seeming more active in lesional skin.Conclusions:  Our data indicate that SL may represent a loss of epidermal melanin unit homeostasis due to chronic irradiation, where keratinocytic changes predominate over melanocytic changes. We hypothesize that abnormal pigment retention in keratinocytes is the primary defect in SL, which may partly explain the therapeutic effect of retinoids.
    Type of Medium: Electronic Resource
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