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Biomedical subjects

A D Rosen

Publications and source records attributed to A D Rosen.

9 recordsLinked to original sources
PubMed1979

Pre- and postsynaptic effects of pancuronium at the neuromuscular junction of the mouse.

The dose-effectiveness of pancuronium as it relates to membrane potentials, action potentials, electrical membrane constants, miniature endplate potentials, endplate potentials, and quantal release was studied in murine phrenic nerve-diaphragm preparations in vitro. Emphasis was placed on comparison of presynaptic with postsynaptic effects of pancuronium under similar experimental conditions. At low concentrations of pancuronium (5 X 10(-8) g/ml or less), no presynaptic effect was found. At high concentration (5 X 10(-7) g/ml), pancuronium depressed quantal release to 26 per cent of control in cut-fiber preparations and 40 per cent of control in high-magnesium preparations. Postsynaptic effects as measured by the amplitude of miniature endplate potentials and relative depolarization induced by 20 microns carbachol, revealed depression to 16 and 22 per cent of control, respectively, at a pancuronium concentration of 5 X 10(-7) g/ml. Pancuronium had no effect on directly elicited action potentials and electrical membrane constants. The authors conclude that presynaptic as well as postsynaptic effects of pancuronium in paralytic doses are essential in contributing to the total efficacy of neuromuscular depression.

Action Potentials↗
PubMed1979

Cortical modification of an epileptogenic focus.

The influence of cerebral cortex on penicillin-induced spikes in striate cortex was studied with the technique of hypothermic block. Direct cooling of the involved or contralateral striate cortex markedly reduced seizure activity. Significant reduction in seizure activity was also seen with cooling of ipsilateral and contralateral visual association cortex. None of the other cortical areas tested had a reproducible effect on the frequency of seizures. These findings are discussed in term of local and remote factors influencing the epileptogenic focus.

Animals↗
PubMed1978

Amyotrophic lateral sclerosis. Clinical features and prognosis.

The clinical diagnosis of amyotrophic lateral sclerosis was identified in 668 patients who were followed up for periods up to three years. This disease was found to be more common in women than previously believed. The five-year survival for all patients was found to be 39.4%, but younger patients had a substantially better prognosis than those in whom the disease was diagnosed when over the age of 50 years. When the mode of onset was considered, the spinal form was associated with a threefold better five-year survival than the bulbar form.

Adolescent↗
PubMed1977

Antidromic activity in visual radiation during evoked cortical responses.

1. Antidromic stimulation of the visual radiation of cats has been used to investigate the possibility that some of the activity in principal geniculate cells following an optic tract stimulus is antidromic. Single spikes were selected from two classes of poststimulus activity to condition the antidromic test spike--the undoubted orthodromic postsynaptic spike and the later spikes, occurring up to 100 ms after the optic tract stimulus. 2. In 15 of 39 cells the minimum antidromic activation times and the minimum spike-spike intervals were found to be shorter and latencies for antidromic stimulation were longer when the conditioning spikes belonged the class of late poststimulus activity. The differences are in accord with the assumption that some of the conditioning spikes were antidromic. 3. Test spikes were frequently found to have long and variable latency when the conditioning spike occurred more than 45 ms after the optic tract stimulus. Possible reasons are briefly discussed. 4. It is suggested that antidromic activity may occur in conditions of the cortex that are more physiological than those associated with a penicillin-induced seizure focus. Some possible mechanisms and functional significance are briefly discussed.

Animals↗
PubMed1976

Influence of association cortex on penicillin discharges in the primary visual cortex.

The influence of visual association cortex on the pattern of neuronal activity in the lateral geniculate body, during penicillin-induced discharges in visula cortex, was studied. In a majority of those geniculate cells which exhibited a pre-penicillin discharge increment in activity, that increment was abolished or significantly reduced during focal hypothermia of the visual association cortex. The frequency of penicillin discharges in visual cortex was, in most cases, reduced during cooling of association cortex. These findings are briefly discussed in terms of corticothalamic interactions.

Animals↗