The in vitro metabolism of Eulan WA New by liver homogenates from freshwater fish

The rate of formation of pentachloro-2-aminodiphenylether (5-PAD) from pentachloro-2-(chloromethylsulphonamido) diphenylether (6-PCSD) by goldfish liver homogenates was studied in a variety of buffers. The highest rate was observed when the homogenate was prepared and assayed in phosphate buffer containing dithiothreitol. The 5-PAD forming activity of liver homogenate preparations from a variety of freshwater fish (goldfish, carp, pike, rainbow trout, perch and eel) showed contrasting species differences. These results could be correlated with information available on the toxicity of the mothproofing agent Eulan WA New (which contains PCSDs) to these fish.     

Action of morphine on guinea-pig myenteric plexus and mouse vas deferens studied by intracellular recording.

Morphine reduces the output of transmitter from the myenteric plexus-longitudinal muscle preparation of the guinea-pig ileum and from the mouse vas deferens. Intracellular recordings were made from ganglion cells of the myenteric plexus and smooth muscle cells of the vas deferens. Synaptic transmission within the myenteric plexus was blocked by hexamethonium. Morphine did not change the properties of the ganglion cells, nor did it affect synaptic potentials. 5-Hydroxytryptamine inhibited acetylcholine release at intraganglionic synapses by an action which was unaffected by morphine. In the vas deferens, excitatory junction potentials were elicited by stimulation of postganglionic adrenergic nerve fibres. The junction potentials were depressed by morphine and levorphanol but not by dextrorphan. This depression was reversed by naloxone. The results indicate that morphine acts directly to reduce transmitter release at the neuro-effector junctions in the myenteric plexus-longitudinal muscle preparation and in the vas deferens in these species.     

The in vitro metabolism by homogenates of goldfish (Carassius auratus) liver of pentachloro-2-(chloromethyl sulphonamido) diphenyl ether, the major component and active ingredient of the mothproofing agent Eulan WA New

After dosing goldfish (Carassius auratus) for 2 hr with pentachloro-2-(chloromethyl sulphonamido) diphenyl ether, 6-PCSD, (the major component of the active ingredients of the mothproofing agent Eulan WA New) in the surrounding water, high concentrations of the corresponding amine pentachloro-2-aminodiphenyl ether, 5-PAD, were found in the liver. This suggests that the liver is a primary site of 5-PAD formation in vivo. Homogenates of goldfish liver showed a 5-PAD forming activity when incubated with 6-PCSD; this activity was destroyed by boiling the homogenate or by treatment with trypsin. The activity was greater at pH 7.4 than at pH 3, 5 or 9. There was no detectable corresponding activity in homogenates of goldfish spleen or digestive tissue or in the digestive tract contents.     

Computer-controlled, patient-interactive, multichannel, implanted neurological stimulators

Programmable implantable neurological stimulation systems with multiple electrodes have many advantages in clinical use, but time-consuming postoperative adjustment of stimulation parameters is a distinct disadvantage. A personal computer interface to standard commercial radiofrequency-coupled devices has been developed, permitting direct patient interaction to expedite this process. In addition, the system permits simulated multichannel operation and implementation of various modulation schemes.     

Communication between the fungus garden and workers of the leaf-cutting ant, Atta sexdens rubropilosa, regarding choice of substrate for the fungus

Bait made from orange peel, containing the fungicide cycloheximide, was initially harvested by workers of Atta sexdens rubropilosa (Forel) and incorporated into the fungus garden as substrate for the fungus. The bait was subsequently rejected by the worker ants days later. Exposure of the fungus to cycloheximide, in laboratory sub-colonies, resulted in the fungus being ‘stressed’. By interchanging normal fungus garden with ‘stressed’ fungus garden, a change in the foraging behaviour of the workers was evident. –Two hypotheses to explain the behavioural changes were tested: a volatile semiochemical is produced by the fungus which affects the foragers directly, or contact between workers (and fungus garden) is necessary for information regarding fungal substrate to be transmitted through the worker force. When pairs of sub-colonies were connected (one colony of each pair exposed to cycloheximide in the bait) and workers were initially prevented from passing from one colony to the other, one colony continued to forage on orange bait while the other did not. When both colonies were allowed to make full contact then both colonies failed to accept orange bait. This discounted the first hypothesis, but supported the second, as a highly volatile chemical should be able to diffuse between colonies. When large foragers were prevented from making contact with the second colony, the information may be communicated by smaller workers.