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Biomedical subjects

J Clark

Publications and source records attributed to J Clark.

At least 559 records · Page 31Linked to original sources
PubMed1968

The extracellular potential field of the single active nerve fiber in a volume conductor.

The potential field of an active fiber in a uniform medium of infinite extent and within a nerve trunk is calculated from transmembrane potential data. The resulting distributions are given quantitatively. A comparison of both magnitude and field pattern in the nerve trunk and infinite medium environments is made and the effect of interstitial conductivity and nerve trunk diameter on potential magnitudes is considered.

Electrophysiology↗
PubMed1966

Dealkylation and loss of capacity for reactivation of cholinesterase inhibited by sarin.

Inhibition of rat brain acetylcholinesterase by (32)P-sarin in vivo results initially in (32)P-isopropylmethylphosphonylated enzyme. The percentage of inhibited enzyme that could not be reactivated by pyridinium aldoxime methochloride (aged enzyme) approximated the amount of radioactivity identified as (32)P-methylphosphonate. The (32)P-isopropyl methylphosphonate not released fromthe inhibited enzyme by the oxime accounted for 51 +/- 10 percent ( standard deviation) of the radioactivity fixed to brain tissue. It showed no correlation with aging and was probably bound to sites other than acetylcholinesterase.

Aging↗
PubMed1966

A mathematical evaluation of the core conductor model.

This paper is a mathematical evaluation of the core conductor model where its three dimensionality is taken into account. The problem considered is that of a single, active, unmyelinated nerve fiber situated in an extensive, homogeneous, conducting medium. Expressions for the various core conductor parameters have been derived in a mathematically rigorous manner according to the principles of electromagnetic theory. The purpose of employing mathematical rigor in this study is to bring to light the inherent assumptions of the one dimensional core conductor model, providing a method of evaluating the accuracy of this linear model. Based on the use of synthetic squid axon data, the conclusion of this study is that the linear core conductor model is a good approximation for internal but not external parameters.

Electrophysiology↗