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Biomedical subjects

D G King

Publications and source records attributed to D G King.

32 records · Page 2Linked to original sources
PubMed1983

On neuronal homology: a comparison of similar axons in Musca, Sarcophaga, and Drosophila (Diptera: Schizophora).

Thoracic axons occurring in Musca and Sarcophaga are similar to those previously reported in the giant fiber pathway of Drosophila. Serial section reconstruction of both species has shown that the cervical giant fiber descending from the brain into the thoracic ganglion and the thoracic motor axon innervating the tergotrochanteral muscle follow courses matching those of similar axons in Drosophila. Likewise in both Musca and Sarcophaga a thoracic axon establishes axoaxonal synapses onto dorsal longitudinal muscle motor neurons. This axon is similar in both course and synaptic configuration to the peripherally synapsing interneuron in Drosophila. Although these similarities suggest that the three axon pairs are homologous in all three fly species, Several differences are also observed. Thus this system of identified axons may be a useful model for investigating phylogenetic variation in specific neuronal form and connectivity.

Animals↗
PubMed1980

Anatomy of the giant fibre pathway in Drosophila. I. Three thoracic components of the pathway.

Activity in the flight muscles and jump muscles in Drosophila can be stimulated by excitation of a pair of giant fibres that enter the thoracic ganglion from the brain. Contrary to previous descriptions, these giant fibres are not themselves motor axons. Each giant fibre contacts both a large motor axon and an interneuron. The motor axon innervates the ipsilateral tergotrochanteral (jump) muscle. The interneuron synapses in turn with the motor neurons that innervate the contralateral dorsal longitudinal flight muscle. The output synapses of this interneuron occur directly onto the motor axons within a peripheral nerve. The unusual peripheral location for these interneuron synapses suggests that the interneuron may function to speed up activation of the motor axons by bypassing integration within the motor neurons' dendritic trees. The synapses are typical dipteran chemical synapses, with occasional reciprocal contacts from the motor axons back onto the interneuron. The interneuron-motor axon synapses may be especially useful for morphological studies of identified synaptic contacts because their peripheral location makes them extremely easy to locate and identify.

Animals↗
PubMed1980

Choice of electrode in electromyography of the external urethral and anal sphincters.

The needle, anal and catheter methods of performing simultaneous cystometry and pelvic floor electromyography were compared in 29 patients. Urethral sphincter electromyographic recordings consistently were satisfactory with a needle electrode, whereas the catheter surface electrode caused recording artifacts and was fragile. Anal sphincter electromyography was more reliable with a needle electrode than with an anal surface electrode.

Electrodes↗
PubMed1980

Computed tomography of the lumbar thecal sac.

With a high resolution modification of a translate--rotate body scanner (EMI CT5005), radiologists may now demonstrate the epidural fat, thecal sac, and axillary pouches of the lower thoracic, lumbar, and sacral spinal canal without using contrast agents. Preliminary results with a newer rotary motion scanner (EMI CT7070) suggest that this scanner achieves sequally good delineation of intracanalicular anatomy.

Adipose Tissue↗
PubMed1980

Superimposition reformatted CT for preoperative lesion localization and surgical planning.

With computer reformatting techniques, it is possible to project any lesion into its proper position with respect to the reformatted midsagittal computed tomography (CT) plane, the reformatted biparietal CT plane, or any other useful reference plane. The calvarial contour depicted on the reformatted midsagittal CT image is exactly comparable to the calvarial contour seen on a true lateral skull radiograph, and the calvarial contour depicted on the reformatted biparietal CT image is exactly comparable to the biparietal calvarial contour seen on the standard frontal skull radiograph. Using simple geometric proportions, therefore, it is easy to transfer the projection of a lesion from the reformatted images onto true lateral and frontal skull radiographs to provide neurosurgeons and radiotherapists with frontal and lateral pictures of the lesion and the skull suitable for planning surgical incisions and radiation portals.

Adult↗
PubMed1979

Anal stimulating electrodes in electromyography.

The Continaid pelvic floor stimulating electrode is useful in reception of electromyographic signals, a use for which the device was not originally conceived. I believe there is money to be saved and some clinical problems can be avoided when this plug is substituted for some others now in clinical use.

Anal Canal↗
PubMed1979

Development of high resolution computed tomography of the spinal cord.

Computed tomography of the spinal cord was a natural development of total body scanning. Much time and effort was spent in order to visualize the spinal cord and the various conditions affecting it. This was achieved by using an EMI CT5005 scanner and a series of step by step modifications and improvements to obtain a very high degree of resolution. The large variety of intraspinal lesions seen at the Montreal Neurological Hospital allowed us, by selecting appropriate cases, to determine the value of CT of the spinal cord.

Humans↗
PubMed1977

Embryonal rhabdomyosarcoma of the prostate.

Embryonal rhabdomyosarcoma of the prostate is typically a rare mesenchymal tumor of young boys, presenting with obstructive urinary symptoms or an abdominal mass. The origin is probably in undifferentiated mesenchymal cells that persist into adult life. Histologically, the tumor cells resemble normal muscle development in a 7 to 10-week fetus. Treatment is combined radical surgery and chemotherapy, and usually radiotherapy as well. The prognosis is extremely poor in all patients. Our case is added to the few in the literature in which this disease occurred in a man more than 50 years old.

Humans↗
PubMed1976

Organization of crustacean neuropil. I. Patterns of synaptic connections in lobster stomatogastric ganglion.

The stomatogastric ganglion of the lobster consists of about thiry neurons, mainly large monopolar cells, which have been well characterized physiologically. This paper presents an anatomical description of this ganglion, emphasizing synaptic connections in the neuropil. The neuron cell bodies are located on the dorsal surface of the ganglion. They send processes into the underlying neuropil mass. The neuropil is differentiated into two regions: a core of coarse neuropil consists of large heavily ensheathed processes; a surrounding region of fine-textured synaptic neuropil consists of smaller unsheather processes. Synapses are found only in synaptic neuropil, not in the core of coarse neuropil. Synaptic contacts, about one million in the entire neuropil, are easily recognized by a set of criteria including presynaptic vesicles and pre- and postsynaptic membrane specializations. Most synaptic contacts invole at least three neural processes, usually one pre- and two postsynaptic elements. Synapses are clustered onto irregular swellings or varicosities on neural processes. These varicosities make both pre- and postsynaptic contacts. Three differenty types of presynaptic profile are recognized. Pyloric dilator, ventricular dilator and lateral posterior gastric neurons belong to type A with clear irregular synaptic vesicles. Lateral pyloric, pyloric, anterior median and dorsal gastric neurons belong to type B with larger clear round vesicles. Many unidentified fibres, presumably stomatogastric nerve afferents, blong to type C with both small clear irregular vesicles and also large dense-core vesicles. The synaptic vesicle types are tentatively correlated with neurotransmitter: type A with acetylcholine, type B with an unknown transmitter, possibly glutamate, and type C with dopamine. The distribution of synaptic contacts on the processes of identified neurons reconstructed from serial section is presented in the following paper.

Animals↗
PubMed1976

Organization of crustacean neuropil. II. Distribution of synaptic contacts on identified motor neurons in lobster stomatogastric ganglion.

Identified neurons in the stomatogastric ganglion of the lobster were examined and reconstructed by serial section electron microscopy. Each motor neuron consists of a soma, a primary process leading directly from the soma to the motor axon which leaves the ganglion, and a group of secondary processes which branch from the primary process and ramify within the neuropil. Synapses are found only on small processes in the synaptic neuropil, never on the primary processes or on larger secondary processes in the coarse neuropil. Nearly every secondary process of every neuron examined makes both pre- and postsynaptic contacts. Hence these neurons are not polarized into distinct pre- and postsynaptic regions but have both input and output distributed over each of the secondary processes in the neuropil. The conncetion between a specific pair of neurons is also distributed over several branches of both the pre- and the postsynaptic neurons. The restriction of synapses to the more distal portions of the secondary processes suggests that no single contact or localized group of contacts can exert an overrriding influence on the neuron by virtue of an especially advantageous position. The close proximity of input and output on most secondary processes suggests that synaptic input may be capable of directly influencing output without the intervention of action potentials. The distribution of specific synapses over several branches of both pre- and postsynaptic neurons suggests that each neuron functions as a whole without differentiation into specialized branches.

Animals↗