Glycocalyx of Epidermal Cells in Vitro: Demonstration and Enzymatic Removal

Guinea-pig epidermal cells in culture possess a glycocalyx coat similar to that in vivo, as revealed by the ruthenium red staining technique. Trypsin. phospholipase C, and lysozyme do not produce any changes of the glycocalyx, while hyaluronidase and neuraminidase lead to partial and subcomplete removal, respectively. Cells stripped of their glycocalyx coat by neuraminidase do not detach from the support and do not show any signs of toxicity. There is complete reconstitution of the glycocalyx within 24 hr

Immediate Pigment Darkening Phenomenon. A Reevaluation of Its Mechanisms

Proposed mechanisms of immediate pigment darkening (IPD) are controversial. They include photooxidation of “premelanin,” changes in the distribution pattern of microfilaments and microtubules, movement of melanosomes to melanocyte dendrites, increased transfer of melanosomes to keratinocytes, and changes in the melanosome distribution pattern in keratinocytes. We investigated the following aspects of IPD: (1) production of IPD by UVA under physiologic and nonphysiologic conditions in full-thickness skin and epidermal sheets; (2) reversibility of IPD in vitro after in vivo and in vitro production; (3) blocking of IPD by disruption of the microfibrillar or microtubular system in vitro; (4) alterations of the cytoskeleton of melanocytes; (5) the melanosome distribution pattern in melanocytes and keratinocytes.The results were as follows: IPD could be elicited in vitro in full-thickness skin and in epidermal sheets. Its production was temperature independent (0°-37°) and was not inhibited by repeated freezing and thawing, or by formalin fixation. IPD was reversible in vitro under tissue culture conditions but only in viable skin. IPD could not be blocked by substances that disrupt the microfibrillar or microtubular system (cytochalasin B, colcemid, vincristine). As shown with a monoclonal antivimentin antibody, IPD-producing UBA doses did not induce changes in the cytoskeleton of melanocytes. No changes in number and distribution patter of melanosomes were observed electron-microscopically and by morphometric analysis of EM micrographs. Productions of IPD does not depend on the structural and functional integrity of themelanocyte cytoskeletal apparatus and is not confined to viable skin, whereas its reversibility is. The fact that no increased melanosome transfer occurs may explain the lack of a UV protective action

Phototherapy and Photochemotherapy of Skin Disease Warwick L.MorisonPhototherapy and Photochemotherapy of Skin Disease1983Praeger PublishersNew York151$28.95

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