Living electrodes: tissue engineering the neural interface.

Soft, cell integrated electrode coatings are proposed to address the problem of scar tissue encapsulation of stimulating neuroprosthetics. The aim of these studies was to prove the concept and feasibility of integrating a cell loaded hydrogel with existing electrode coating technologies. Layered conductive hydrogel constructs are embedded with neural cells and shown to both support cell growth and maintain electro activity. The safe charge injection limit of these electrodes was 8 times higher than conventional platinum (Pt) electrodes and the stiffness was four orders of magnitude lower than Pt. Future studies will determine the biological cues required to support stem cell differentiation from the electrode surface.

Integrated electrode and high density feedthrough system for chip-scale implantable devices.

High density feedthroughs have been developed which allow for the integration of chip-scale features and electrode arrays with up to 1141 stimulating sites to be located on a single implantable package. This layered technology displays hermetic properties and can be produced from as little as two laminated 200 µm thick alumina sheets. It can also be expanded to a greater number of layers to allow flexible routing to integrated electronics. The microelectrodes, which are produced from sintered platinum (Pt) particulate, have high charge injection capacity as a result of a porous surface morphology. Despite their inherent porosity the electrodes are electrically stable following more than 1.8 billion stimulation pulses delivered at clinically relevant levels. The ceramic-Pt constructs are also shown to have acceptable biological properties, causing no cell growth inhibition using standard leachant assays and support neural cell survival and differentiation under both passive conditions and active electrical stimulation.

Time-Temperature Conditions of Gyros.

Four gyro operations in foodservice establishments were examined for the possibility that pathogenic foodborne bacteria could survive and/or grow during each step of these operations. Gyros cooked on broilers attained temperatures lethal to vegetative pathogenic bacteria on the surface of the meat and in the thin layer just below the surface, but nowhere else. However, only meat sliced from the surface was normally put in gyro sandwiches or otherwise served. The temperatures of gyros as they cooled were such that bacterial growth could occur, both on the surfaces and within the mass. After gyros had been cooked and cooled, as many as 10,000 Clostridium perfringens per gram were recovered from samples taken just under the surface. Temperatures of gyro meat during reheating varied with the method of reheating, and they were in safe ranges when slices of meat were reheated in microwave ovens and steam chambers. When gyros were reheated on broilers, however, temperatures lethal to vegetative pathogenic bacteria occurred at and near the surfaces only. Recommendations for procedures to use for cooking, slicing, hot holding, cooling, and reheating gyros to prevent this product from becoming a vehicle of foodborne illness are given. Emphasis is on using the entire gyro the day it is originally cooked, rapid cooling of any leftover portions, and thorough reheating of leftover gyros.