The action of gamma-vinyl-GABA and gamma-acetylenic-GABA on the resting and stimulated release of GABA in vivo.

The effects of gamma-vinyl-GABA (4-amino-hex-5-enoic acid, RMI 71754) and gamma-acetylenic-GABA (4-amino-hex-5-ynoic acid, RMI 71645), the selective and irreversible inhibitors of GABA-transaminase (E.C. 2.

Use of Moore swabs for isolating Vibrio cholerae from sewage.

The Moore swab method was shown to be a practical and sensitive technique for the isolation of Vibrio cholerae from sewage. In each of three instances in which cholera patients lived in homes connected to municipal sewers, V. cholerae was isolated from the community sewage plant intake at the time of the patients illness.

A unique environmental occurrence of hydrogen sulfide positive Escherichia coli.

For the first time in nearly 4 decades of surveillance, H2S positive Escherichia coli have been isolated from Calcasieu Lake and River. These results are reported because of recent clinical interest in these organisms.

Actions of tremorgenic fungal toxins on neurotransmitter release.

The neurochemical effects of the tremorgenic mycotoxins Verruculogen and Penitrem A, which produce a neurotoxic syndrome characterised by sustained tremors, were studied using sheep and rat synaptosomes. The toxins were administered in vivo, either by chronic feeding (sheep) or intraperitoneal injection 45 min prior to killing (rat), and synaptosomes were subsequently prepared from cerebrocortical and spinal cord/medullary regions of rat, and corpus striatum of sheep. Penitrem A (400 mg mycelium/kg) increased the spontaneous release of endogenous glutamate, GABA (gamma-aminobutyric acid), and aspartate by 213%, 455%, and 277%, respectively, from cerebrocortical synaptosomes.

Peripheral sensory stimulation and the release of transmitter amino acids in vivo from specific regions of cerebral cortex.

The effects of sensory stimulation on the release of amino acids from sensorimotor and visual cortex have been studied using a superfusion technique. Electrical stimulation of the brachial plexus contralateral to the superfusion cannula increased significantly the release of glutamate and glutamine from the sensorimotor cortex of anaesthetized rats. No clear effect was observed with the other amino acids.

Evidence for presynaptic cholinergic receptors on dopaminergic terminals: degeneration studies with 6-hydroxydopamine.

Intraventricular injections of 6-hydroxydopamine (6-OHDA) caused a significant decrease in the tyrosine hydroxylase of striatal synaptosomes of rats, without influencing GABA levels. Significant decreases in the muscarinic and nicotinic receptors also occurred in this preparation after 3 days. The receptors were measured by specific binding studies with N-methylatropine and alpha-bungarotoxin respectively.

Peripheral sensory stimulation and the release of transmitter amino acids in vivo from specific regions of cerebral cortex.

The effects of sensory stimulation on the release of amino acids from sensori-motor and visual cortices have been studied using a superfusion technique. Electrical stimulation of the brachial plexus contra-lateral to the superfusion cannula increased significantly the release of glutamate and glutamine from the sensori-motor cortex of anesthetized rats. No clear effect was observed with the other amino acids.

Metabolic and secretory processes in nerve-endings isolated from post-mortem brain.

Isolated nerve ending particles (synaptosomes) prepared from rat and human cerebral cortex, after varying conditions of post-mortem storage were shown to possess good structural and morphological integrity and metabolic activity. Respiration, potassium retention, lactate dehydrogenase content, and stimulus-induced release of transmitter candidate amino acids, as well as the neuropeptide somatostatin, were measured. These preparations from post-mortem material showed properties which were closely comparable with similar preparations from fresh material.

Defective binding of thrombin to platelets in myeloid leukaemia.

Platelets from patients with myeloid leukaemia showed reduced aggregation with collagen or thrombin. These platelets also had a lower capacity to bind thrombin. This lower thrombin binding is due to a decrease in the total quantity of receptors available and not because of a change in the affinity.

Biochemical evidence for the presence of presynaptic receptors on dopaminergic nerve terminals.

Two compartments of striatal synaptosome dopamine were identified by differential labelling with the isotopic presursors, L-tyrosine and Dopa, and from specific radioactivity measurement. Either, endogenous or exogenous L-tyrosine could provide a source for the dopamine pool synthesised and released in response to K+ depolarization, whereas external DOPA did not enter this pool. Acetylcholine (0.

Uptake studies of taurine in vivo and its effects on the course of experimental focal epilepsy in rats.

The passage of orally administered taurine across the intestinal wall to the blood plasma and target sites of neuromuscular excitability has been studied. This has been correlated with the effect of repeated oral dosing on the manifestations of cobalt-induced epilepsy in the rat. The blood-brain barrier and the organ distribution of taurine uptake have important implications in testing its effect on hyperexcitability phenomena.