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Biomedical subjects

L E White

Publications and source records attributed to L E White.

17 recordsLinked to original sources
PubMed1992

Equanimity.

Explore the source record for details and available documents.

Career Choice↗
PubMed1991

Distributions of choline acetyltransferase and acetylcholinesterase activities in the retinal layers of the red-tailed hawk and road runner.

The activities of choline acetyltransferase and acetylcholinesterase were assayed in submicrogram samples from layers of red-tailed hawk and road runner retina. Both enzyme activities were concentrated in and near the inner plexiform layer. Within the inner plexiform layers of both species, activities of each enzyme were concentrated in two bands, one in each half of this layer. Little choline acetyltransferase activity was found superficial to the middle third of the inner nuclear layer. The distributions of acetylcholinesterase activities corresponded well to those of choline acetyltransferase, except in the outer plexiform layer and the outer margin of the inner nuclear layer of the hawk. These distributions of enzyme activities indicate that populations of amacrine cells in the retinae of these species are cholinergic. In addition to these same cells and presumably cholinoceptive amacrine and ganglion cells, acetylcholinesterase activity in the hawk was associated with a population of horizontal cells that may be unrelated to synaptic cholinergic neurotransmission. Choline acetyltransferase activities associated with amacrine somata and processes were about four times greater in the hawk than in the road runner, suggesting important differences in the density and function of cholinergic elements between species. Possible synaptic relationships in the inner plexiform layer consistent with the interspecies differences in enzyme activities are considered.

Acetylcholinesterase↗
PubMed1990

Distributions of choline acetyltransferase and acetylcholinesterase activities in the retinal layers of pigeon red and yellow fields.

The activities of choline acetyltransferase and acetylcholinesterase were assayed in submicrogram samples from layers of pigeon retina. Red and yellow fields were sampled separately to investigate quantitatively the relationship between these enzymes of acetylcholine metabolism and the gradient of inner plexiform layer complexity, increasing from the yellow field to the red. Choline acetyltransferase and acetylcholinesterase activities were concentrated in and near the inner plexiform layer, within which two peaks of activity for each enzyme were obtained. The distributions of enzyme activities indicate that populations of amacrine cells in the pigeon retina are cholinergic. The quantitative similarities between the enzyme activities in red and yellow fields suggest that the cholinergic system may not be specifically involved in the increase in inner plexiform layer complexity across the pigeon retina.

Acetylcholinesterase↗
PubMed1989

High-frequency components in epileptiform EEG.

We analyzed the spectral content of interictal and ictal EEG of rats treated with metrazol. Significant power was present in the EEG between 100 and 800 Hz ictally but not interictally. Since high-frequency activities appeared to accompany spiking episodes, a computer algorithm was developed to recognize rapid voltage fluctuations or high-frequency components in EEG. The algorithm turned out to be effective in the identification of seizure spikes. The significance of high frequencies in EEG spikes and the advantage of the spike selection algorithm are discussed.

Algorithms↗
PubMed1989

Cortical control of tongue contractility in the rat under ketamine anaesthesia.

1. Cortico-lingual and linguo-cortical interconnectivity was investigated in ketamine-anaesthetized rats mounted onto a stereotaxic apparatus. The tip of the tongue was tied to a force displacement transducer to monitor tongue retrusions. The tongue cortical area was exposed in one or both hemispheres to record evoked potentials or spontaneous electroencephalographic (EEG) activity, or to stimulate electrically with single square pulses of up to 50 V and 0.25 ms pulse width. 2. The results showed that (i) tongue retrusions elicited by electrical stimulation were identical to those induced by ketamine; (ii) ketamine-induced tongue contractions correlated in time with cortical EEG potentials which were easily distinguished from the background noise; (iii) haloperidol (2.5 mg/kg, i.m.) suppressed the cortically evoked tongue contractions as well as the ketamine-induced contractions. 3. These results suggest that ketamine-induced tongue retrusions may involve the cortex in their mediation if not their generation and that this may provide a basis for the suppression of dyskinetic activity during sleep or unconsciousness.

Anesthesia↗
PubMed1989

Neurosonographic features of central nervous system infections in infancy and childhood.

Infections of the central nervous system (CNS) are a serious threat to the developing brain and are a major cause of neurologic handicap in the young. Of the neuroimaging modalities available, cranial ultrasonography has become an important technique in providing information about intracranial infection because of its portability, low cost, minimal morbidity, and diagnostic image quality. Authors of recent reports described ultrasonographic changes in brain parenchyma, extracerebral fluid, and ventricles. Parenchymal changes have been observed with cerebritis, edema, hemorrhage, infarction, and abscess formation; changes in extracerebral fluid include effusion and empyema; and ventricular changes associated with ventriculitis and hydrocephalus have been reliably described. By identifying changes associated with intracranial infections, ultrasonography has emerged as a technique that provides valuable information in making the diagnosis, identifying complications, and directing decisions in management of CNS infection.

Bacterial Infections↗
PubMed1979

The regions of the fornix longus: a morphologic analysis.

The areas surrounding the fornix longus were examined using the rapid Golgi method, acetylcholinesterase (AChE) histochemistry, and horseradish peroxidase histochemistry. Parasagittal Golgi impregnated sections revealed the neuronal configurations of the nuclei of the fornix longus. An interstitial nucleus within the fiber bundle and a bed nucleus were observed. They coursed from midline dorsal hippocampus and became continuous with caudal septal regions (notably septotriangularis). Neurons in the interstitial nucleus were spine-poor whereas bed nucleus neurons were spiny. Numerous axon collaterals were observed in the area. These gave rise to many apparent synaptic boutons. This intrinsic connectivity within the fornix longus was verified physiologically. Acetylcholinesterase histochemistry revealed the presence of AChE positive fibers traveling in both the bed nucleus and fornix longus. These fibers appeared to emanate from the regions of the diagonal band and formed a marked density in the bed nucleus. Also apparent was a striking midline density of AChE that forms a distinct midline fornix. All of these AChE positive fibers appeared to be related to the medial portions of the dorsal hippocampus from its septal pole to the dorsal psalterium. Injections of horseradish peroxidase into medial septal regions resulted in pick-up of the peroxidase in a specialized portion of hippocampus. Specifically, neurons were identified in the alvear portions of the midline dorsal hippocampus as well as in the alveus and stratum oriens (occasionally) of CA 3. It was concluded that the area of the fornix longus is situated in the mainstream of many incoming and outgoing hippocampal fiber systems. Because of this unique situation and the bi-directionality of the projections fibers of the area, the bed nucleus and interstitial nucleus of the fornix longus were postulated to play a crucial role in normal hippocampal processing.

Acetylcholinesterase↗
PubMed1978

Retinal venous occlusion and ABO blood-groups.

The distribution of ABO blood-groups in 79 patients with a retinal venous occlusion (RVO) was not significantly different from that of local blood donors. In 67 of these patients it was found that the visual outcome six months after the RVO is significantly associated with the patient's ABO blood-group. For central and branch retinal vein occlusions taken together 18 percent of patients with blood-group A had a vision of 6/9 or better in the affected eye, whereas 46 percent of patients with blood-group 0 and 49 percent of patients with blood-groups, O, B or AB achieved this vision.

ABO Blood-Group System↗
PubMed1976

The rodent neostriatum: a Golgi analysis.

In the adult rodent, coronal sections of Golgi impregnations of the neostriatum display a compact segregation of axon fascicles, neuronal clusters, and dendritic bundles thus forming an areolar configuration. Isolated neurons are rarely seen. The dorsomedial region of the neostriatum appears free of axon fascicles and dendritic bundles. Horizontal and sagittal sections of the neostriatum show clusters of cells parallel to axon fascicles. The neurons exhibit spine-laden dendrites with an initial spine-free segment. Neonatal impregnations exhibit a different configuration. Neonatally, cells tend to cluster but there is no bundling of dendrites. Neurons are spine-free or have protospines on the soma and the dendrites, including the initial segment. Transition from neonate to adult configuration is discernible at about 15 days after birth. The neostriatum of carnivores exhibits a different structure from the rodent neostriatum. This difference is associated with a developed anterior limb of the internal capsule in the carnivore. The axon fascicle-free portion of the carnivore neostriatum lacks dendritic bundles and pallisades. Portions near the capsule with axon fascicles appear similar to the rodent neostriatum with dendritic bundlings and pallisading. Such findings emphasize the importance of total neuronal configuration (neuronal-architectonics) in morphologic analyses.

Animals↗
PubMed1975

Some factors affecting mother-infant relations in rhesus monkeys.

The effects of six independent variables on rhesus mother-infant relations are examined by comparing sub-groups of mother-infant pairs differing in only one of the variables. Variables compared and discussed include mother's parity, previous experience and social status, sex of the infant and the presence of peers. All variables except maternal parity appeared to affect the relationship, but none produced effects that were wholly consistent over all comparisons. Further tentative analyses were made of some age effects and interactions between variables which may have accounted for the inconsistencies.

Animals↗
PubMed1975

Muscarinic stimulation of cardiac guanylate cyclase.

Right ventricular kitten papillary muscles were incubated with dibutyryl adenosine 3',5'-monophosphate (db-cAMP) at varying concentrations from 1 X 10(-4) M to 1 X 10(-3) M. A positive inotropic effect was observed with all concentrations of db-cAMP. Concomitant administration of 5 X 10(-4) M monobutyryl guanosine 3',5'-monophosphate and 1--2 X 10(-4) M db-cAMP did not produce an inotropic response. At the biochemical level cardiac guanyl cyclase activity is enhanced 2--3 times with acetylcholine and this enhancement is completely blocked by atropine. This increased activity appears to be the result of a decrease in the Michaelis constant (Km) for GTP. Calcium also produces a significant activation of guanyl cyclase activity.

Acetylcholine↗