A gated electronic switch for stimulation and recording with a single electrode
A circuit design is described for an electronic device which is gate controlled to rapidly switch electrode connections between a stimulator and an amplifier. An integrated switch in the circuit is operated by transistor-transistor logic pulses and will conduct analog signals of up to 15 V amplitude. Electrographic records made using the switch show multi-unit spike discharge after repetitive stimulation of the amygdala in the kindled rat.
Closed-Loop Deep Brain Stimulation for Parkinson’s Disease
Optimal outcomes of deep brain stimulation (DBS) surgery are often an elusive goal. 
 
 
Constant “one-program” stimulation does not reflect the reality of changing clinical symptoms. 
 
 
Closed-loop technology might provide a solution. 
 
 
Closed-loop design will likely integrate multi-sourced sensing data, computed using information from a population database and individual hierarchical paradigms to continuously titrate parameters of stimulation. 
 
 
Proof of principle already exists for the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) primate model and in human Parkinson’s disease (PD) patients. 
 
 
Many elements of such a feedback system have already been developed.
l-Phenylalanine dehydrogenase from Brevibacterium sp. for production of l-phenylalanine by reductive amination of phenylpyruvate
SummaryFor production of l-phenylalanine the reductive amination of phenylpyruvate, catalyzed by phenylalanine-dehydrogenase was examined. To reach high levels and a sufficient stability of the inducible intracellular enzyme, growth conditions of Brevibacterium sp. are optimized. For continuous production of l-phenylalanine in an enzyme membrane reactor, the kinetic parameters of the partially purified enzyme are determined.In continuous production a space time yield of 37.4 g l-Phe l-1 d-1 can be reached.By means of the measured kinetic parameters and simultaneous calculation of the mass balances of all reaction components the behaviour of the reactor can be simulated. For certain conditions the multi-enzyme-system shows multiple steady-states.