Human recombinant EGF protein delivered by a biodegradable cell transplantation system.

We have previously shown a new approach to expand cultured human keratinocytes and reconstitute the epidermis in full-thickness wounds using a new microsperical transport system. This was a new approach to increase the cell yield for seeding without altering the anchoring proteins by enzymatic steps. That time we used Cytodex 3 which failed to be degraded and induced an inflammatory reaction in a t-cell-deficient organism. Therefore, we have investigated another microcarrier consisting of PLGA, which is a well-known carrier material for cell culture and transplantation. After coating the PLGA carrier with gelatine the seeding time of viable cells reached 4 h and the cell gain after 7 days of spinner culture was 16-fold. At 14 days after transplantation, we could detect a new stratified epithelium in our full-thickness wound healing model. Because cytokines play a major role in wound healing, we loaded this carrier material with different concentrations of rhEGF, showing a dose dependent release of the protein in vitro and in vivo. This result might lead to a different approach in the treatment of wounds.

Impairment in a discrimination reversal task after D1 receptor blockade in the pigeon "prefrontal cortex".

Dopamine (DA) is known to modulate cognitive functions of the prefrontal cortex (PFC) of mammals, especially via D1 receptor mechanisms. Like the PFC, the neostriatum caudolaterale (NCL) of birds is characterized by dopaminergic input, and NLC and PFC lesions cause similar deficits. The significance of DA in a color discrimination reversal was assessed by evaluating the effects of bilateral infusions of the D1 receptor antagonist SCH 23390 into the NCL of pigeons (Columba livia). Reversal deficits were qualitatively similar to those in mammals. At a low dose, perseveration occurred predominantly to the incorrect stimulus. Higher doses caused additional spatial perseveration. The data demonstrate, for the first time, that D1 receptor mechanisms in the NCL of pigeons contribute substantially to its function in cognitive processes. Thus, the avian NCL and mammalian PFC could represent functionally equivalent neural networks under control of the DA system.

Single unit activity during a Go/NoGo task in the "prefrontal cortex" of pigeons.

Single unit activity was recorded during a delayed auditory/visual Go/NoGo task from the neostriatum caudolaterale (NCL) of pigeons, a multimodal associative avian forebrain structure comparable to the prefrontal cortex (PFC). The animals were trained to mandibulate (to open their beak) during the Go period after which they received a drop of water as reward. Neuronal activity changes were observed during the delay period (DELAY) between auditory and visual stimulation, to the onset of the visual stimulus or to the delivery of the reward. In some neurons, responses were related to the behavioral significance of the stimulus such that the neuronal activity was statistically different between Go and NoGo trials. Moreover, some units anticipated the upcoming reward or changed their firing frequency in a correlated manner prior to beak movements. These neuronal activity patterns suggest that the NCL provides a neural network that participates in the integration and processing of external stimuli in order to generate goal directed behavior.