Biomedical subjects

Wolfgang Meyer

Publications and source records attributed to Wolfgang Meyer.

5 recordsLinked to original sources

PubMed2007

Development of a new calcium phosphate powder-binder system for the 3D printing of patient specific implants.

A key requirement for three-dimensional printing (3-DP) of medical implants is the availability of printable and biocompatible powder-binder systems. In this study we developed a powder mixture comprising tetracalcium phosphate (TTCP) as reactive component and beta-tricalcium phosphate (beta-TCP) or calcium sulfate as biodegradable fillers, which can be printed with an aqueous citric acid solution. The potential of this material combination was demonstrated printing various devices with intersecting channels and filigree structures. Two post-processing procedures, a sintering and a polymer infiltration process were established to substantially improve the mechanical properties of the printed devices. Preliminary examinations on relevant application properties including in vitro cytocompatibility testing indicate that the new powder-binder system represents an efficient approach to patient specific ceramic bone substitutes and scaffolds for bone tissue engineering.

3T3 Cells↗

PubMed2005

Interactions between brushlike polyacrylic acid side chains on a polyacrylate backbone in dioxane-water.

Densely grafted polyacrylic acids (d-PAAs) with overcrowded PAA side chains on the polyacrylate main chains were synthesized and characterized. Acryloyl poly(tert-butyl acrylate) macromonomer [M-P(tert-BA)] was prepared with a definite chain length (n=29) by atom-transfer radical polymerization (ATRP), then homopolymerization was carried out to produce densely grafted P(tert-BA)s with polyacrylate main chains of two different lengths (m=27 and 161). The two d-PAAs were obtained by hydrolyzing d-P(tert-BA)s in the presence of trifluoroacetic acid (TFA). The d-PAAs exhibit intermolecular and intramolecular hydrogen bonding between the carboxylic groups of PAA side chains in dioxane and pyridine; both were investigated using proton nuclear magnetic resonance (1H NMR) spectroscopy. The intermolecular hydrogen bonding was found to be dependent on polymer concentration, temperature, and water content. The intramolecular association between the PAA side chains was found to produce a contraction of the hydrodynamic volume of the d-PAA. Intermolecular hydrogen bonding produces aggregates, as demonstrated by dynamic light scattering (DLS). The clusters were found to shrink as the overall water concentration decreased, and this effect is tentatively explained by considering the gradient in chemical potential of water inside the clusters in comparison with the solvent phase.

Acrylic Resins↗

PubMed2005

Synaptic plasticity in micropatterned neuronal networks.

Synaptic plasticity is thought to be of central importance for information processing by the nervous system. Additionally, specific neuronal connectivity patterns in the brain are implicated to play a role in the perception, processing and storage of incoming signals. Experimental control over connectivity within functional neuronal networks is therefore a promising approach in research on signal transduction and processing by the nervous system. A cell culture system is presented that allows experimental determination of neuronal connectivity patterns in an in vitro network. Rat embryonic cortical neurons were grown on patterns of extracellular matrix proteins applied to polystyrene substrates by microcontact printing. Cells comply well with the pattern and form synaptic connections along the experimentally defined pathways. Chemical synapses identified by double patch-clamp measurement showed paired pulse depression as well as frequency-dependent depression in response to trains of stimuli. This type of short-term plasticity has similarly been reported by others in brain slices. Thus, the system reproduces features central for neuronal information processing while the architecture of the network is experimentally manipulable. The ability to tailor the geometry of functional neuronal networks offers a valuable tool both for fundamental questions in neuroscientific research and a wide range of biotechnological applications.

Action Potentials↗

PubMed2004

State-of-the-art serological techniques for detection of antibodies against tick-borne encephalitis virus.

Indirect immunofluorescence, ELISA and immunoblot test systems for the detection of antibodies against tick-borne encephalitis (TBE) virus were developed and evaluated. Sera from 112 patients with clinically characterized TBE virus infections, 27 patients with antibodies against dengue or yellow fever virus and 100 healthy blood donors were investigated for anti-TBE virus antibodies. The assays yielded sensitivities of 91-95% and specificities of 91-94%. The test systems are valuable new tools for the diagnosis and monitoring of TBE virus infections.

Antibodies, Viral↗

PubMed2003

[Psychotherapy in a tax-financed sectorized health care system--a happy ending or disaster for English patients?].

Compared to other European countries' health systems, the NHS is very different. Finance by taxes, standards set by frameworks and statutory bodies to monitor nationwide the outcome, are virtually unknown on the Continent. For the patients there are considerable differences in how they are referred to psychotherapy and receive their treatment based on guaranteed standards. Health professionals identified with the NHS have to cope with a plethora of government directives.

Cost Control↗