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Biomedical subjects

E K Killam

Publications and source records attributed to E K Killam.

36 records · Page 2Linked to original sources

Biogenic amines and the photomyoclonic syndrome in the baboon, Papio papio.

The role of biogenic amines in the proclivity of the baboon, Papio papio, to exhibit an epileptoid response to flashing light was studied. Intraventricular injections of epinephrine and norepinephrine reduced or blocked the photomyoclonic syndrome without modifying ongoing behavior. Epinephrine was effective at doses of 100 mg and more, and norepinephrine was effective at doses of 250 mg and more. Neither intraventricular injections of as much as 1.5 mg of dopamine and 1.0 mg of serotonin nor chronic systemic administration of L-dopa and L-tryptophan affected the syndrome, but reserpine, administered chronically at doses of 0.5 and 1.0 mg/kg/day, induced photosensitivity in previously nonphotosensitive animals. Seizure testing of usually photosensitive animals 12 hours after reserpine, 0.5 mg/kg, showed that the drug prevented totally or reduced the intensity of seizures in these animals. Studies of the spontaneous electroencephalogram and of visually evoked potentials of the reserpine-treated animals revealed changes in power spectra and in the averaged evoked response from the occipital area which paralleled the induction of photosensitivity. The probability that epinephrine and norepinephrine brain concentrations are essential for inhibitory modulation and control of seizures in this species is discussed.

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Measurement of anticonvulsant activity in the Papio papio model of epilepsy.

The status of Papio papio as a model of clinical epilepsy has been reviewed. The anticonvulsant effects of single doses of various classic and experimental agents have been compared against seizures induced in the P. papio by intermittent light stimulation. Long-acting but not short-acting barbiturates have been shown fully to control seizures with minor sedative effects. Diphenylhydantoin (in chronic doses only) and trimethadione are often effective but not consistently so. Diazepam and clonazepam block seizures at very low doses both acutely and chronically. However, an initial dose well above threshold seems essential if anticonvulsant effects are to be maintained under chronic administration of these compounds. Carbamazepine and SC 13504 (1-benzhydryl-4(6 methyl-2-pyridylmethyleneimino)piperazine), as well as two nonstimulant analogues of amphetamine, were shown to be promising anticonvulsants in this model. A biphasic action of tetrahydrocannabinol, anticonvulsant at a few micrograms per kilogram but not at higher doses, was also demonstrated. Finally, the anticonvulsant action of intraventricular epinephrine and norepinephrine was reported.

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