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Vol. 19 No. 2
Bioanalytical Systems, Inc. / December 2000


Foreword (9k)
I have been disturbed lately by the number of issues on which people take extreme positions...

Acetylcholinesterase Inhibitors Are Neither Necessary nor Desirable for Microdialysis Studies of Brain Acetylcholine (329k)
Acetylcholine (ACh), one of the major neurotransmitters in brain, has an important role in various types of cognition, including attention and memory. ACh is critical to the neurocognitive dysfunction in Alzheimer’s disease and possibly other psychiatric disorders such as schizophrenia. Furthermore, the development of drugs which increase the availability of brain ACh is a major research goal. Thus, direct measurement of brain ACh release under physiological conditions, using in vivo microdialysis, in laboratory animals is of great importance. Because of the low concentration of ACh, many of the microdialysis studies published to date required Acetylcholinesterase (AChE) inhibitors in the perfusion medium to increase basal ACh. However, the artificially increased concentration exerts a significant influence on the cholinergic system, thereby making interpretation of drug effects problematic. We have recently developed a highly sensitive method of ACh measurement, which requires no AChE inhibitors. Advantages of the new method are discussed.

Simulation of Cyclic Voltammetry Using Finite Difference Methods
This article discusses the application of finite difference methods to the simulation of cyclic voltammograms with particular reference to the BAS simulation software DigiSim®.

The Electrochemistry of Thiol Self-Assembled Monolayers (SAMs) on a Hanging Mercury Drop Electrode (HMDE) (71k)
The electrochemistry of functionalized self-assembled monolayers on Hg is studied by cyclic voltammetry and AC voltammetry. The results suggest that thiols can be adsorbed either chemically or physically depending on the Hg potential. The transformation between these two states occurs via an oxidation-reduction process. While a multi-layer of short chemisorbed thiols is formed under positive potentials than the oxidation-reduction process, a dense monolayer is self-assembled under more negative potentials.

Ramifications of Pump-Switching Step Gradients for Bioanalytical LC/MS/MS (60k)
Two separate isocratic LC pumps were configured to perform fast, step gradients for bioanalytical LC/MS/MS assays, simultaneously reducing analysis time and ion suppression, and improving peak shape. Although the technique offers significant advantages for bioanalytical LC/MS/MS assays, it also presents some practical challenges. A newly designed LC pump, the BAS PM-92, is shown to be ideally suited for pump-switching step gradients.

Products, In the EC Literature, In the MD Literature, Miscellany (79k)

In the EC Literature: Adrian Bott, BAS, discusses papers on a special fullerene derivative, reagentless biosensors and much more.

In the LC Literature: Bruce Solomon of BAS reviews discussions on use of a dual-mode electrochemical detector to determine 3-nitrotyrosine by high-pressure LC and several other recent papers.
In the MD Literature: James Gitzen of BAS looks at articles on: the possible reduction in certain behaviors by mGlu2/3 agonists due to changes in dopaminergic activity; the delivery of ondansetron HCI via transdermal microdialysis probes; and microdialysis to separate inorganic anions for analysis in wastewater clean-up.
Miscellany: Upcoming conferences and symposia, faculty vacancies, the new Indiana Instrumentation Institute and a discussion of available tools and services for CNS research.


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