Adsorption of albumin and IgG to porous and smooth titanium

The possibility to load submicrometer porous titanium surfaces with relatively small proteins, albumin and immunoglobulin G (IgG) was investigated. The loading ability is of interest due to the possibility of slow release of molecules from biomaterial surfaces, and may be important for the manipulation of wound healing around prostheses. Iodine-125 (125I) labeled albumin and IgG were adsorbed onto smooth and to porous titanium with a pore diameter of 200-300 nm. The smooth and porous surfaces were divided into three groups: hydrophilic, hydrophobic, or to amine-terminated silane (3-aminopropyltriethoxysilane) that bound proteins via glutaraldehyde. The protein solution pH and protein concentrations were varied, and the adsorption experiments made without or in the presence of calcium and magnesium ions. The adsorbed amounts were quantified with a gamma counter. Two to eleven times more proteins adsorbed onto porous than smooth surfaces and the adsorbed amounts increased with increasing protein concentration (0.1-10 mg/ml) during a constant incubation time. The elutability by sodium dodecyl sulphate (SDS) was incomplete on porous surfaces.     

Construction of a Microstructured Collagen Membrane Mimicking the Papillary Dermis Architecture and Guiding Keratinocyte Morphology and Gene Expression

A papillary‐structured collagen fibril membrane is created, mimicking the 3D‐architecture of the human papillary dermis. Primary human keratinocytes cultured to confluency on papillar‐structured films are compared to keratinocytes cultured on flat membranes. Microscopical evaluation reveals the presence of morphologically distinct cells at the base of the papillar structures that are not observed on flat membranes. Gene expression microarrays and RT‐qPCR indicate that these cells are in a more proliferative/migrational state, whereas cells on flat membranes have a more differentiated expression profile. Immunohistochemical stainings confirm these results. In conclusion, specific collagen architecture can direct keratinocyte behavior, and this may be used to further improve skin regeneration.

     

On the equality of Hausdorff and box counting dimensions

By viewing the covers of a fractal as a statistical mechanical system, the exact capacity of a multifractal is computed. The procedure can be extended to any multifractal described by a scaling function to show why the capacity and Hausdorff dimension are expected to be equal.     

Trace Formulas for Stochastic Evolution Operators: Weak Noise Perturbation Theory

Periodic orbit theory is all effective tool for the analysis of classical and quantum chaotic systems. In this paper we extend this approach to stochastic systems, in particular to mappings with additive noise. The theory is cast in the standard field-theoretic formalism and weak noise perturbation theory written in terms of Feynman diagrams. The result is a stochastic analog of the next-to-leading ? corrections to the Gutzwiller trace formula, with long-time averages calculated from periodic orbits of the deterministic system. The perturbative corrections are computed analytically and tested numerically on a simple 1-dimensional system.     

Clinical use of laboratory thyroid tests and investigations.

Laboratory thyroid testing involves in vitro tests for autoimmune thyroid disease, thyroid dysfunction and neoplasia, in vivo investigations of thyroid function, and investigations of thyroid morphology. The authors describe, in tabular form, the diagnostic information carried by the tests and their clinical utility as well as clinically relevant interferences.     

Adsorbate-induced alloy phase separation: a direct view by high-pressure scanning tunneling microscopy

The influence of high pressures of carbon monoxide (CO) on the stability of a Au/Ni(111) surface alloy has been studied by high-pressure scanning tunneling microscopy. We show that CO induces a phase separation of the surface alloy at high pressures, and by means of time-lapsed STM movies we find that Ni atoms are removed from the surface layer during the process. Density functional theory calculations reveal the thermodynamic driving force for the phase separation to be the Au-induced compression of the CO overlayer with a resulting CO-CO repulsion. Furthermore, the atomistic mechanism of the process is shown to be kink-site carbonyl formation and evaporation which is found to be enhanced by the presence of Au.     

A new approach to dynamic deactivation in capillary zone electrophoresis

This paper describes a simple means of obtaining high resolution separations of basic proteins at a pH below their pl. Small amounts of a cationic fluorosurfactant are added to the running buffer. A positively charged wall is thereby obtained which will repel positively charged proteins. The particular chemistry of fluorosurfactants is believed to enhance the efficiency of the deactivation. Examples are presented of the separation of some model proteins, including a human insulin-like growth factor (IGF-I), and a misfolded by-product of the growth factor.