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Biomedical subjects

A C Webb

Publications and source records attributed to A C Webb.

At least 73 records · Page 4Linked to original sources
PubMed1980

Analysis of malate dehydrogenase isozymes from anuran amphibian ovary by isoelectric focusing.

The isozymes patterns of ovarian malate dehydrogenase (MDH) from various anuran amphibian series were analyzed by isoelectric focusing (IEF). Extensive variability was observed in both the soluble (sMDH) and mitochondrial (mMDH) patterns with as few as two and as many nine bands being visualized in different species. The mean pIs for sMDH ranged from 4.5 to 8.3 and those for mMDH fell between 5.1 and 8.2. The sMDHs are considerably more heat labile in Rana species living in northern latitudes compared to those from southern states. Inhibition with p-chlormercuribenzoate (PCMB) revealed the importance of sulfhydryl groups for the activity of sMDHs, while the functional requirement for these groups in mMDHs appears to be of lesser importance. Observations from these studies lend support to the accumulating evidence that Rana pipiens from such southern locations as New Mexico may have undergone speciation.

Animals↗
PubMed1980

Medical coordination in airport disasters.

The goals of an Airport Disaster Plan includes the care, treatment and transportation of the wounded with the quality and quantity of care that minimizes the mortality and morbidity of the survivors of a crash. Coordination of the medical aspects of these plans requires participation by physicians, nurses, ambulance and hospital personnel, psychologists, and psychiatrists. To maintain these divers groups in a state of readiness for a potential disaster which may have a frequency of 5-20 years is a challenging problem. This paper addresses methods of accomplishing this goal.

Aircraft↗
PubMed1979

The effects of sleep on neurons in isolated cerebral cortex.

Slabs of cat parietal cortex with some 2 mm of underlying white matter were surgically isolated from the rest of the nervous system, without interference with the superficial blood supply. Wire micro-recording electrodes were inserted into the isolated cortex; bone, muscle and skin wounds were repaired and the animal allowed to recover from anaesthesia. The adequacy of surgical isolation was examined histologically 8--12 weeks after operation. Only one of the six preparations reported here showed surviving neural connections with the rest of the brain. Soon after operation, spontaneous bursts of neural activity appeared within the isolated area. These became more frequent until neural discharge was continuous but irregular. Our records were made from this time onwards. The interval distributions obtained from neurons within the isolated area did not differ significantly from log-normal curves. When the unrestrained animal fell asleep, there was no significant alteration in the model interval or geometric standard deviation of interval distributions recorded from cells in isolated cortex. The interval distributions of neurons in isolated cerebral cortex resembled those of neurons in the intact cortex of an alarmed animal. It is concluded that the reduction of modal interval that is shown by neurons in intact cortex when an animal falls asleep is probably due to the neural influence of infracortical structures.

Action Potentials↗
PubMed1979

The correlation between discharge times of neighbouring neurons in isolated cerebral cortex.

The purpose of the experiments was to find out whether neighbouring neurons in chronic preparations of neurally isolated cerebral cortex are more likely to fire synchronously than are similar neurons in the intact brain. Chronically implanted extracellular microelectrodes were used to obtain simultaneous records of the spontaneous discharges of neighbouring neurons in the suprasylvian gyrus of the unanesthetized, unrestrained cat. We have examined multi-unit records obtained from neurons in islands of neurally isolated cortex; these records have been compared with similar records from neurons in the same cortical region of the intact brains of control animals. In isolated cortex, neighbouring neurons showed a tendency to discharge in near synchrony. In contrast, there was a random temporal relation between the firing times of adjacent nerve cells of intact cortex, provided the cat was awake. These results, taken together with the relevant observations of other workers, may indicate the manner in which biologically important information is transmitted within the mammalian brain.

Action Potentials↗
PubMed1979

The measurement of receptive field properties of neurones in the visual cortex of the conscious, mobile cat.

We have assessed the accuracy, reliability and ease of use of a technique for determining the receptive field properties of cells in the visual cortex of the conscious, unrestrained cat. Our tests have provided the following results: (1) Minimal behavioural training is necessary; it is often possible to train an animal in only two sessions. (2) A surprising degree of optical stability can be achieved. Measurements of receptive field properties are consequently reliable and repeatable. (3) We are not certain of the exact limits of accuracy which can be achieved, but we usually determine orientation specificity +/- 5 degrees, and measure receptive field positions +/- 1.5 degrees.

Animals↗
PubMed1976

An autoradiographic study of tritiated uridine incorporation into the larval ovary of Xenopus laevis.

The in vitro incorporation of 3H-5-uridine into the germinal and somatic cells of the larval ovary of Xenopus laevis has been studied using both light and electron microscope autoradiography. Incubation for only one hour in the presence of precursor revealed that the follicle cells are highly active in rRNA synthesis, whereas substantial oogonial nucleolar labeling was not detected for several hours. Semi-quantitative analysis of high-resolution autoradiograms indicated that the density of silver grains associated with "nuage" in oogonia was almost 4-fold greater than the surrounding cytoplasm. This strongly suggests that a significant amount of RNA is associated with "nuage" at this stage of Xenopus oogenesis, in addition to its well documented protein composition. "Pulse-chase" experiments further suggest that the nuage-associated RNA is stable for at least 24 hours. These results are discussed (within the limitations imposed by the methodology) both in relation to other studies on the composition of nuage in a wide variety of germinal cell types and in the light of growing speculation that nuage and germinal granules are synonymous.

Animals↗