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  • Küçük Resim
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    AFM feature definition for neural cells on nanofibrillar tissue scaffolds.
    (Scanning, 2011-12-23) Tiryaki, Volkan; Khan, Adeel A; Ayres, Virginia M.
    A diagnostic approach is developed and implemented that provides clear feature definition in atomic force microscopy (AFM) images of neural cells on nanofibrillar tissue scaffolds. Because the cellular edges and processes are on the same order as the background nanofibers, this imaging situation presents a feature definition problem. The diagnostic approach is based on analysis of discrete Fourier transforms of standard AFM section measurements. The diagnostic conclusion that the combination of dynamic range enhancement with lowfrequency component suppression enhances feature definition is shown to be correct and to lead to clearfeatured images that could change previously held assumptions about the cell–cell interactions present. Clear feature definition of cells on scaffolds extends the usefulness of AFM imaging for use in regenerative medicine. SCANNING 34: 316–324, 2012. C 2012 Wiley Periodicals, Inc.
  • Küçük Resim
    Öğe
    Nanofibrillar scaffolds induce preferential activation of Rho GTPases in cerebral cortical astrocytes
    (International Journal of Nanomedicine, 2012-07-12) Tiryaki, Volkan; Ayres, Virginia M.; Khan, Adeel A; Ahmed, Ijaz; Shreiber, David I; Meiners, Sally
    Cerebral cortical astrocyte responses to polyamide nanofibrillar scaffolds versus poly-L-lysine (PLL)-functionalized planar glass, unfunctionalized planar Aclar coverslips, and PLL-functionalized planar Aclar surfaces were investigated by atomic force microscopy and immunocytochemistry. The physical properties of the cell culture environments were evaluated using contact angle and surface roughness measurements and compared. Astrocyte morphological responses, including filopodia, lamellipodia, and stress fiber formation, and stellation were imaged using atomic force microscopy and phalloidin staining for F-actin. Activation of the corresponding Rho GTPase regulators was investigated using immunolabeling with Cdc42, Rac1, and RhoA. Astrocytes cultured on the nanofibrillar scaffolds showed a unique response that included stellation, cell–cell interactions by stellate processes, and evidence of depression of RhoA. The results support the hypothesis that the extracellular environment can trigger preferential activation of members of the Rho GTPase family, with demonstrable morphological consequences for cerebral cortical astrocytes.