Biomedical subjects
Publications and source records attributed to L S Kane.
Diastolic dysfunction may be associated with increased morbidity and mortality. In this article, an overview of the pathophysiology of diastolic dysfunction is discussed and the findings of Doppler echocardiography used to aid in its diagnosis are reviewed.
In crayfish and squid giant nerve fibers, glutamate appears to be an axon-glia signaling agent. We have investigated glutamate transport and metabolism by crayfish central nerve fibers in order to identify possible mechanisms by which glutamate could subserve this non-synaptic signaling function. Accumulation of radiolabeled L-glutamate by desheathed cephalothoracic nerve bundles was temperature and Na(+) dependent, linear with time for at least 8h and saturable at about 0.5-1mM L-glutamate. Most accumulated radiotracer was associated with the periaxonal glial sheath and remained as glutamate. Compounds known to block glutamate transport in invertebrate peripheral nerves or mammalian brain slices or cell cultures were also effective on crayfish central nerve fibers. Tissue radiotracer levels were only 3% of control levels when 1mM p-chloromercuriphenylsulfonate was present, and 13%, 20%, 26%, 38% and 42% of control levels, respectively, when L-cysteate, L-cysteine sulfinate, L-aspartate, D-aspartate or DL-threo-beta-hydroxyaspartate was present. L-Glutamine, GABA, N-methyl-DL-aspartate, alpha-aminoadipate and D-glutamate were without inhibitory effect on tissue tracer accumulation. Radiolabeled D-aspartate was an equivalent non-metabolized substitute for radiolabeled L-glutamate. D-Aspartate, p-chloromercuriphenylsulfonate and GABA had comparable effects on isolated medial giant nerve fibers.These studies indicate that L-glutamate is taken up primarily by the periaxonal glia of crayfish central nerve fibers by a low-affinity, saturable, Na(+)-dependent transport system and is retained by the fibers primarily in that form. Our results suggest that the glia are not only the target of the glutamate signal released from non-synaptic regions of the crayfish medial giant axon during high-frequency stimulation, but that they are also the primary site of its inactivation.
Only a few intracellular S-nitrosylated proteins have been identified, and it is unknown if protein S-nitrosylation/denitrosylation is a component of signal transduction cascades. Caspase-3 zymogens were found to be S-nitrosylated on their catalytic-site cysteine in unstimulated human cell lines and denitrosylated upon activation of the Fas apoptotic pathway. Decreased caspase-3 S-nitrosylation was associated with an increase in intracellular caspase activity. Fas therefore activates caspase-3 not only by inducing the cleavage of the caspase zymogen to its active subunits, but also by stimulating the denitrosylation of its active-site thiol. Protein S-nitrosylation/denitrosylation can thus serve as a regulatory process in signal transduction pathways.
Subjects estimated the duration of five different time intervals, either filled or unfilled, in relation to one or two standard intervals. Half of the subjects were presented with the standard at the beginning of the experiment only, and half were presented with the standard before every interval. The five estimations were then used to calculate, for each subject, the exponent in Stevens' Power Law which describes the form of the power relationship. The resulting over-all exponent of .91, although nearly linear, was significantly different from 1.0. The data were then analyzed by a 2 X 2 X 2 analysis of variance which showed a significant interaction between presenting the standard either once or before each interval with the duration of the standard.