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Peterbrough, United Kingdom

Koester P.J.,University of Rostock | Tautorat C.,University of Rostock | Beikirch H.,Electronic Appliances | Gimsa J.,University of Rostock | Baumann W.,University of Rostock
Biosensors and Bioelectronics | Year: 2010

This short communication reports on the innovative method of the local micro-invasive needle electroporation (LOMINE) of single adherent cells. The investigation of cellular reactions in living cell cultures represents a fundamental method, e.g. for drug development and environmental monitoring. Existing classical methods for intracellular measurements using, e.g. patch clamp techniques are time-consuming and complex. Present patch-on-chip systems are limited to the investigation of single cells in suspension. Nevertheless, the most part of the cells of the human body is adherently growing. Therefore, we develop a new chip system for the growth of adherent cells with 64 micro-structured needle electrodes as well as 128 dielectrophoretic electrodes, located within a measuring area of 1mm2. With this analytical chip, the intracellular investigation of electro-chemical changes and processes in adherently growing cells will become possible in the near future. Here, we present first intracellular measurements with this chip system. © 2010 Elsevier B.V. Source

Zietz C.,University of Rostock | Bergschmidt P.,University of Rostock | Lange R.,Electronic Appliances | Mittelmeier W.,University of Rostock | Bader R.,University of Rostock
International Journal of Artificial Organs | Year: 2013

Aim: Total knee arthroplasties have reached a high grade of quality and safety, but most often fail because of aseptic implant loosening caused by polyethylene wear debris. Wear is generated at the articulating surfaces, e.g. caused by third-body particles. The objective of this experimental study was to determine the wear of tibial polyethylene inserts combined with metallic and ceramic femoral com-ponents under third-body wear conditions initiated by bone cement particles. Methods and Materials: Wear testing using a cemented unconstrained bicondylar knee endoprosthe-sis (Multigen Plus CR knee system) was performed in a knee wear simulator. Tibial polyethylene inserts were combined with the identical femoral component design, but made of two different materials (cobalt-chromium and ceramic). Bone cement debris including zirconium oxide particles was added every 500,000 cycles between the articulating surfaces. After 5 million load cycles, the amount of wear was determined gravimetrically and compared with results from standard wear test conditions. The surfaces of tibial inserts were also analyzed. Results: The average gravimetrical wear of the tibial polyethylene inserts in combination with cobalt-chromium and ceramic femoral components under third-body wear conditions amounted to 31.88 ± 4.53 mg and 13.06 ± 1.88 mg after 5 million cycles, respectively, and was higher than under standard wear test conditions in both cases. Conclusions: The wear simulator test demonstrates that wear of polyethylene inserts under third-body wear conditions, in combination with ceramic femoral components, was significantly lower than with metallic femoral components. © 2013 Wichtig Editore. Source

Electronic Appliances | Date: 2015-05-27

Grills cooking appliances; cooling installations for liquids; water sterilizers; friction lighters for igniting gas.

Staehlke S.,University of Rostock | Koertge A.,Electronic Appliances | Nebe B.,University of Rostock
Biomaterials | Year: 2015

Detailed insights into the complex cellular behavior at the biomaterial interface are crucial for the improvement of implant surfaces with respect to their acceptance and integration. The cells perceive microtopographical features and, in consequence, rearrange their adhesion structures like the actin cytoskeleton and adaptor proteins. But little is known about whether these altered cellular phenotypes have consequences for intracellular calcium signaling and its dynamics. To elucidate if an artificial, geometrical microtopography influences calcium ion (Ca2+) mobilization in osteoblasts, human MG-63 cells were stained with the calcium dye Fluo 3-acetoxymethyl ester and set on defined silicon-titanium (Ti) arrays with regular pillar structures (P5, 5×5×5μm) and compared with planar Ti. To induce an immediate calcium signal, cells were stimulated with adenosine 5'-triphosphate (ATP). Interestingly, osteoblasts on micropillars expressing a shortened actin cytoskeleton were hampered in their calcium mobilization potential in signal height as well duration. Even the basal level of the intracellular Ca2+ concentration was reduced, which was accompanied by a disturbed fibronectin synthesis. The expression of the voltage-sensitive calcium channels Cav1.2, Cav1.3 (L-type) and Cav3.1, Cav3.2, Cav3.3 (T-type) as well as the signaling proteins phospho-AKT and phospho-GSK3α/β remained unaffected on pillars. The topography-dependent calcium dynamics observed here provide new insights into how topographical cues alter cell functions - via the intracellular Ca2+ signaling. © 2014 Elsevier Ltd. Source

Elter P.,Electronic Appliances | Weihe T.,University of Rostock | Buhler S.,University of Rostock | Gimsa J.,University of Rostock | Beck U.,Electronic Appliances
Colloids and Surfaces B: Biointerfaces | Year: 2012

Using single-cell force spectroscopy, we compared the initial adhesion of L929 fibroblasts to planar and nanostructured silicon substrates as a function of fibronectin concentration. The nanostructures were periodically grooved with a symmetric groove-summit period of 180. nm and a groove depth of 120. nm. Cell adhesion strength to the bare nanostructure was lower (79. ± 13%) than to the planar substrate, which we attribute to reduced contact area. After pre-incubation with a low fibronectin concentration (5μg/ml) the adhesion strengths to both surfaces increased, with adhesion strength on the nanostructure outweighing that of the planar substrate by 133% ± 14%. At a high fibronectin concentration (25μg/ml) the adhesion strengths on both surfaces further increased and showed wide variations. In parallel, the nanostructure lost its clear advantage over the planar substrate. Our results demonstrate that cell adhesion is influenced by substrate topography and fibronectin, which mediate the interplay between specific interactions, non-specific interactions, and cell mechanics. Two parallel processes govern the initial adhesion strength: the detachment of the cell body from the substrate and the extraction of tethers from the cell membrane. The duration of the latter process is determined by tether lifetimes, and is a major contributor to the overall work required for cell-substrate detachment. Cell body detachment and tether lifetimes are affected by surface topography and may be strongly modulated by the presence of adsorbed proteins, whereas the tether extraction forces remained unchanged by these factors. © 2012 Elsevier B.V.. Source

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