Christopher Y Chan

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Quasi steady-state electric fields were applied across the isolated turtle cerebellum to study the relationship between applied field, neuronal morphology and the modulation of the neuronal spike firing pattern. Spiking elements were identified electrophysiologically using extracellular recording methods and by subsequent horseradish peroxidase injection,(More)
1. Transmembrane potential (TMP) responses of Purkinje cells (PCs) in isolated turtle cerebellum to externally applied quasi-steady-state electric fields aligned with the dendritic axis were continuously measured using simultaneous intracellular and extracellular recording. TMP was obtained by subtraction of extracellular voltage fields from intracellular(More)
Prenatal cocaine exposure produces sustained neurobehavioral and brain synaptic changes closely resembling those of animals with defective AMPA receptors (AMPARs). We hypothesized that prenatal cocaine exposure attenuates AMPAR signaling by interfering with AMPAR synaptic targeting. AMPAR function is governed by receptor cycling on and off the synaptic(More)
The characteristic reduction and binding of nitroimidazoles to cellular macromolecules in the absence of oxygen allows their use for detection and characterization of hypoxia. The biodistribution of a new nitroimidazole, EF5 (2-[2-nitro-1H-imidazol-1-yl]-N-(2,2,3,3,3-pentafluoropropyl) acetamide), in mice bearing EMT6 tumors is described. Detection methods(More)
Taurine is an endogenous brain substance with robust neuromodulatory and possible neuroprotective properties. Though other mechanisms of action have been reported, its interaction with the NMDA (N-methyl-D-aspartic acid) receptor is undocumented. We investigated taurine's interaction with the NMDA receptor using electrophysiological and receptor binding(More)
Exhaustive photoaffinity coupling of flunitrazepam to living spinal cord neurons reduced the capacity of benzodiazepines to potentiate the electrophysiologically measured GABA response. In qualitative agreement with reversible binding data the dose-response curve for enhancement of the GABA response by benzodiazepines was shifted to the right, indicating(More)
An external electric field applied parallel to longitudinal axis of neurons selectively depolarizes either end and thereby activates voltage-sensitive conductance changes in a large population of neurons. Here, we characterized such population responses in the in vitro turtle cerebellum. The responses were recorded and analyzed using a multimodal approach:(More)
Taurine, an endogenous amino sulfonic acid, exhibits numerous neuropsychopharmacological activities. Previous studies in our laboratory have shown that it is an effective anti-cataleptic and neuro-protective agent. Current investigations show that acute or chronic administration of psychotropic drug cocaine may increase extracellular release of endogenous(More)
The ability of several homologous benzodiazepine and heterologous nonbenzodiazepine ligands to alter the conductance increase induced in spinal cord neurons by gamma-aminobutyric acid (GABA) was determined. Complete dose-response curves were carried out on individual neurons, reducing error introduced by cell-to-cell variability. The efficacies of(More)
HCT116 human colon carcinoma xenografts were grown in nude mice. Frozen sections of control and irradiated tumors were stained and analysed for the distribution and extent of hypoxia and apoptosis. Tissue oxygen partial pressure was measured by immunohistochemical staining of hypoxia-dependent metabolites of the 2-nitroimidazole EF5. Apoptosis was assessed(More)