Transplantation of dopaminergic ventral mesencephalic (VM) tissue into the basal ganglia of patients with Parkinson's disease (PD) shows at best moderate symptomatic relief in some of the treated ...cases. Experimental animal studies and clinical trials with allogenic and xenogenic pig-derived VM tissue grafts to PD patients indicate that one reason for the poor outcome of neural transplantation is the low survival and differentiation of grafted dopaminergic neurons. To improve dopaminergic cell survival through a gene-therapeutic approach we have established and report here results of lipid-mediated transfer of the gene for human glial cell line-derived neurotrophic factor (GDNF) to embryonic (E27/28) porcine VM tissue kept as organotypic explant cultures. Treatment of the developing VM with two mitogens, basic fibroblast growth factor and epidermal growth factor, prior to transfection significantly increased transfection yields. Expression of human GDNF via an episomal vector could be detected by
in situ hybridization and by the measuring of GDNF protein secreted into the culture medium. When compared to mock-transfected controls, VM tissue expressing recombinant GDNF contained significantly higher numbers of tyrosine hydroxylase-positive neurons in the cultured VM tissue. We conclude that lipid-mediated gene transfer employed on embryonic pig VM explant cultures is a safe and effective method to improve survival of dopaminergic neurons and may become a valuable tool to improve allo- and xenotransplantation treatment in Parkinson's disease.
This study presents design and implementation of a system which performs wireless power transfer and data transmission for very high data rate in implanted monitoring system. The proposed system is ...powered by implanted energy storage which can be rechargeable by 4-coil inductive link. The system supports low-power/high data rate transmitter for carrying digitalized sensor data. The performance of transmitter based on cross-coupled oscillator is improved significantly. The integrated circuits are manufactured in 0.18 μm CMOS technology. The hermetically sealed circuits are validated in in-vivo experiments. Wireless power transfer is realized at 8 MHz achieving 30% efficiency for delivering 10 mW at a distance of 10 mm. A communication channel is established between the implant and the base station with 12 Mbps data rate. A transmitted set of neural monitoring data from a rat with epilepsy seizure is also presented.
Biological macromolecules with catalytic activity can be created artificially using two approaches. The first exploits a system that selects a few catalytically active biomolecules from a large pool ...of randomly generated (and largely inactive) molecules. Catalytic antibodies and many catalytic RNA molecules are obtained in this way. The second involves rational design of a biomolecule that folds in solution to present to the substrate an array of catalytic functional groups. Here we report the synthesis of rationally designed polypeptides that catalyse the decarboxylation of oxaloacetate via an imine intermediate. We determine the secondary structures of the polypeptides by two-dimensional NMR spectroscopy. We are able to trap and identify intermediates in the catalytic cycle, and to explore the kinetics in detail. The formation of the imine by our artificial oxaloacetate decarboxylases is three to four orders of magnitude faster than can be achieved with simple amine catalysts: this performance rivals that of typical catalytic antibodies.
The expression of Xenopus laevis larval and adult globin genes after phenylhydrazine-induced anemia has been investigated at the cellular and molecular levels by means of cloned cDNA probes specific ...for the four main larval and the four main adult globin mRNA species. In the circulating blood of anemic metamorphic larvae there are at least two distinct populations of erythroblasts containing either larval or adult globin mRNA sequences. The cells expressing adult sequences replace those expressing larval ones at the end of metamorphosis. Under the influence of anemia the qualitative pattern of transcribed RNA species is not changed, but the larval to adult transition takes place earlier during development. This would imply that this transition is not strongly correlated with the morphological changes of metamorphosis. The abundance of the different larval globin mRNA species is similar and, as compared to control animals, not affected by the phenylhydrazine treatment. In anemic adults no reactivation of larval gene expression has been observed. The different adult globin mRNA species are present in comparable abundance, but the phenylhydrazine treatment appears to enhance expression of the alpha A II and beta A II genes, as compared to nonanemic individuals.
