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Biomedical subjects

S Muchnik

Publications and source records attributed to S Muchnik.

At least 73 records · Page 4Linked to original sources
PubMed1975

In vivo and in vitro miniature end-plate potentials at various external K concentrations.

In order to obtain a nore reliable picture of transmitter release, spontaneous synaptic activity was studied in vivo in the rat soleus neuromuscular junction. The in vivo miniature end-plate potential (MEPP) recordings were compared with those obtained in vitro and, in both circumstances, MEPP frequency was measured at external potassiumconcentrations ranging from 5 to 15 mM. The influence of external potassium loading on intra- and extracellular potassium concentration also estimated by measuring the muscle ionic composition and water distribution at normal and high plasma potassium concentrations. The MEPP frequencies recorded in vivo were consistently lower than those observed in vitro for all external potassium concentrations studied (P less than0.01). These data suggest that better experimental conditions are maintained in thein vivo preparations, since the intracellular potassium increase that follows the external potassium loading can only partially justify the observed differnce and other factors, such as anesthetic effects, etc, may be ruled out.

Animals↗
PubMedDate not supplied

Familial congenital facial diplegia: electrophysiologic and genetic studies.

A 13-year-old boy with autosomal-dominant congenital facial diplegia was evaluated by electrophysiologic and genetic investigations. Thirteen members of his family were affected over 4 generations. The electrophysiologic studies revealed blink reflex abnormalities. Both R1 and R2 responses were prolonged on the left side after ipsilateral stimulation, while R2 was also delayed by contralateral stimulation. Ipsilateral R1 and R2 were of normal latencies when the right side was stimulated. A third ipsilateral response at 63 msec of latency could be obtained when stimulating the left side. These findings suggest functional damage to the brainstem. Further support for this interpretation was provided by the prolonged time between waves I and V, bilaterally, documented by study of brainstem auditory evoked potentials.

Adolescent↗