Influence of surface topography on osteoblast response to fibronectin coated calcium phosphate thin films.

The ability to engineer biomaterial surfaces that are capable of a dynamic interaction with cells and tissues is central to the development of medical implants with improved functionality. An important consideration in this regard is the role played by the extracellular proteins that bind to an implant surface in vivo. Deliberate use of an ad-layer of such proteins on an implant surface has been observed to guide and direct cell response. However, the role that changes in surface topography might play in determining the nature of this cell-protein-surface interaction has not been investigated in detail. In this study, calcium phosphate (CaP) thin films have been deposited onto substrates with varying topography such that this is reflected in the (conformal) CaP surface features. A fibronectin (FN) ad-layer was then deposited from solution onto each surface and the response of MG63 osteoblast-like cells investigated. The results revealed that in all cases, the presence of the adsorbed FN layer on the CaP thin films improved MG63 cell adhesion, proliferation and promoted early onset differentiation. Moreover, the nature and scale of the response were shown to be influenced by the underlying CaP surface topography. Specifically, MG63 cell on FN-coated CaP thin films with regular topographical features in the nanometer range showed statistically significant differences in focal adhesion assembly, osteocalcin expression and alkaline phosphase activity compared to CaP thin films that lacked these topographical features. As such, these data indicate that surface topography can be used to further influence cell adhesion and downstream differentiation by enhancing the effects of a surface adsorbed FN layer.

Characterisation of calcium phosphate/titanium dioxide hybrid coatings.

The role of titanium dioxide (TiO2) as a means to engender enhanced stability into calcium phosphate (Ca-P) coatings has been well recognised. Several different methods have been used to create such Ca-P/TiO2 hybrid layers on a range of substrates. This paper reports the properties of a Ca-P/TiO2 system created by the sputter deposition of hydroxyapatite onto a titanium surface and the subsequent thermal diffusion of TiO2 through the porous Ca-P layer. The role of temperature in determining the surface contribution from TiO2 has been determined. Coatings annealed up to 600 degrees C did not exhibit any hybrid nature in the uppermost surface, however the coatings annealed to 700 degrees C did show the presence of both HA and rutile TiO2. The surfaces annealed to 800 degrees C were predominantly rutile TiO2. It was also observed that the Ca/P ratio decreased with increasing annealing temperature and that the coating annealed to 700 degrees C had a value of 1.82 +/- 0.07, which was closest to stoichiometric HA. Furthermore, the coatings that were annealed to 700 degrees C displayed a Ca-P/TiO2 hybrid nature, specifically in their uppermost surface and supported the growth and proliferation of osteoblast-like cells more readily when compared to the HA coatings or the rutile TiO2 surfaces.

Multiple eruptive milia in a 15-year-old boy.

We present a 15-year-old boy with periorbital idiopathic multiple eruptive milia. He represents the youngest case to date of this unusual dermatosis.

Xanthoerythrodermia perstans and alopecia mucinosa in a patient with CD-30 cutaneous T-cell lymphoma.

Xanthoerythrodermia perstans (XEP) is a distinctive variant of large-plaque parapsoriasis. Along with alopecia mucinosa and lymphomatoid papulosis, there is a strong association between large-plaque parapsoriasis and evolving cutaneous T-cell lymphoma (CTCL). In some reports, large-plaque parapsoriasis was suggested to be a precursor lesion that converted to CTCL in 10 to 30 percent of cases. We describe a patient who presented clinically with both XEP and alopecia mucinosa and was subsequently shown to have CD-30 CTCL.