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Biomedical subjects

D G King

Publications and source records attributed to D G King.

At least 19 recordsLinked to original sources
PubMed1995

Methods and materials for porcelain veneers.

Porcelain veneers are an esthetic, relatively conservative restoration used to cover the facial surface of the teeth. Following proper guidelines, the practitioner can achieve successful results as a matter of routine. This article reviews the most current literature published on this subject to bring practitioners up to date on clinical methods and materials used for porcelain veneers.

Cuspid↗
PubMed1990

Combined exfoliation and pigment dispersion syndrome.

Both exfoliation syndrome and pigmentary dispersion syndrome can lead to secondary glaucoma. We treated five patients who had pigmentary dispersion and who subsequently developed exfoliation. In one patient who had bilateral pigment dispersion syndrome, the presence of exfoliation increased the difficulty of controlling intraocular pressure in the affected eye. In a monocular patient, exfoliation and pigmentary dispersion were concurrently present with characteristic defects of both pigmentary dispersion and exfoliation as seen by transillumination defects of the iris. A third patient had bilateral pigmentary dispersion and uncontrollable intraocular pressure in an eye with exfoliation. Despite argon laser trabeculoplasty, the pressure remained uncontrolled. Another patient had a filtering operation in the left eye, with gradually increasing intraocular pressure in the right eye. Exfoliation material complicated the pressure control in the unoperated on eye. Another patient had an eight-year history of glaucoma in the left eye for which filtering surgery was performed. Exfoliation was present in both eyes with controlled pressure in the filtered eye but uncontrolled pressure in the nonfiltered eye.

Anterior Eye Segment↗
PubMed1990

Serpiginous choroidopathy associated with elevated factor VIII-von Willebrand factor antigen.

Elevated Factor VIII-von Willebrand factor antigen levels are associated with vascular endothelial injury in several disorders, including scleroderma, Raynaud's phenomenon, polymyalgia rheumatica, and temporal arteritis. Eight patients with serpiginous choroidopathy were evaluated with the use of quantitative immunoelectrophoresis for Factor VIII-von Willebrand factor antigen. The serpiginous choroidopathy patients had a mean Factor VIII-von Willebrand factor activity of 226 +/- 47.3%, whereas a disease-free, age- and sex-matched control group had a mean activity of 107 +/- 28%. These findings are statistically significant (P greater than 0.005) and suggest that in some patients, serpiginous choroidopathy represents an occlusive vascular phenomenon that involves the choroidal circulation.

Adult↗
PubMed1989

Phylogenetic diversity of cellular organization in the cardia of muscoid flies (Diptera: Schizophora).

In each of 30 dipteran species, representing 13 acalyptrate and 7 calyptrate families, the cardia is formed from specialized cells at the junction between foregut and midgut. Foregut epithelium forms the stomodeal valve; midgut epithelium envelops the valve to form the cardia's outer wall. Cytological characteristics within these epithelia differ from region to region and from species to species. Since the cardia secretes the peritrophic membrane, cardias with diverse patterns of cellular differentiation may be expected to produce peritrophic membranes with similarly diverse properties. Close relatives often share more details of cardia structure than do distantly related taxa. Within the monophyletic Calyptratae, a common pattern of cellular differentiation includes three distinct zones of columnar midgut cells enclosing a flanged stomodeal valve. Among species in the paraphyletic Acalyptratae, midgut typically includes a single zone of tall columnar cells, while the valve may be spheroidal, cylindrical, conical, or flanged. The correlation of phylogenetic distance with divergence in cardia organization implies a strong influence of ancestry upon current structure, regardless of current diet. However, at least some of the observed diversity in cardia structure is associated with dietary divergence. Calyptrate flies with derived blood-feeding behavior display cellular differentiation that is simplified from that seen in calyptrate relatives with less specialized feeding habits. This evolutionary modification suggests that cardia organization and hence peritrophic membrane structure can adapt to dietary changes, with possible significance for the spatial organization of digestive processes and interactions with ingested microorganisms.

Animals↗
PubMed1988

Cellular organization and peritrophic membrane formation in the cardia (proventriculus) of Drosophila melanogaster.

The peritrophic membrane of Drosophila melanogaster consists of four layers, each associated with a specific region of the folded epithelial lining of the cardia. The epithelium is adapted to produce this multilaminar peritrophic membrane by bringing together several regions of foregut and midgut, each characterized by a distinctively differentiated cell type. The very thin, electron-dense inner layer of the peritrophic membrane originates adjacent to the cuticular surface of the stomadeal valve and so appears to require some contribution by the underlying foregut cells. These foregut cells are characterized by dense concentrations of glycogen, extensive arrays of smooth endoplasmic reticulum, and pleated apical plasma membranes. The second and thickest layer of the peritrophic membrane coalesces from amorphous, periodic acid-Schiff-positive material between the microvilli of midgut cells in the neck of the valve. The third layer of the peritrophic membrane is composed of fine electron-dense granules associated with the tall midgut cells of the outer cardia wall. These columnar cells are characterized by cytoplasm filled with extensive rough endoplasmic reticulum and numerous Golgi bodies and by an apical projection filled with secretory vesicles and covered by microvilli. The fourth, outer layer of the peritrophic membrane originates over the brush border of the cuboidal midgut cells, which connect the cardia with the ventriculus.

Animals↗
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↗