Biomedical subjects

L A Marco

Publications and source records attributed to L A Marco.

3 recordsLinked to original sources

PubMed1979

Effects of mercuric chloride on the resting membrane potentials of blue crab (Callinectes sapidus) muscle fibers.

The effects of concentrations of mercuric chloride ranging from 3.68 to 368 microM (1--100 ppm) on the resting membrane potentials of muscle fibers in the extensor muscle of the carpopodite in walking legs of adults blue crabs were investigated in vitro. Glass micropipettes filled with saturated solutions of potassium chloride and conventional electronic equipment were used. Resting membrane potentials in uncontaminated artificial sea water averaged -78 mV +/- 4 mV (S.E.M.). Mercuric chloride added to the control bath at 3.68 or 9.2 microM did not affect the resting membrane potentials. At 18.4 microM threshold effects were obtained in 50% of the preparations. At concentrations ranging from 25.7 to 368 microM progressive deterioration of membrane polarization occurred as the mercury concentration was increased. This effect was irreversible despite multiple washes with normal sea water. We conclude that mercuric chloride has very powerful toxic effects at the peripheral motor effector elements in blue crabs. These results do not, of course, rule out more central effects on enzymatic systems or neuronal networks.

Animals↗

PubMed1979

Succinylcholine drug interactions during electroconvulsive therapy.

Electroconvulsive therapy (ECT) is frequently described as being almost free of absolute contraindications. However, drug interactions with succinylcholine pose potential hazards to which this paper calls attention. In addition to its neuromuscular-blocking action, succinylcholine has other acetylcholine-like effects. Drugs which inhibit cholinesterase activity or which inhibit acetylcholine release or synthesis may produce prolonged respiratory paralysis when combined with succinylcholine. The increasing longevity of the population receiving chemotherapy for physical ailments implies that greater numbers of these patients may also become candidates for ECT and therefore be at risk for adverse drug interactions with succinylcholine. Of particular importance to the psychiatrist are the various psychotropic drugs that have been reported to interact with succinylcholine. Precautions in using drug combinations and treatment of complications are described.

Animals↗

PubMedDate not supplied

Narcolepsy with tinnitus aura: interpretation.

A fifty-five year old man was admitted to our ward for evaluation of narcoleptic-cataplectic attacks which were signaled by a "hissing sound like high pressure steam leaking out of a pipe." This tinnitus was exclusively localized to the right ear. It started about sixty-to-ninety seconds before the cataplectic episode (affecting mostly the jaw muscles) and lasted through part of it as it became progressively louder toward the end and ceased abruptly. It is postulated that, along with the collapse of tonic musculature of the mandible, a decrease of proprioceptive tone also affected the tensor tympani muscle leaving the middle ear vulnerable to internally generated noise. We further postulate that tinnitus was finally arrested by the generation of phasic bursts of contraction of the tensor tympani and/or the stapedius muscle at a later stage of cataplexy.

Electroencephalography↗