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Biomedical subjects

J L Shannon

Publications and source records attributed to J L Shannon.

15 recordsLinked to original sources
PubMed2000

Emergency repair of type A aortic dissection in type IV Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome type IV is a distinctive syndrome in which thin and fragile skin, premature ageing, bruising and scarring are combined with lethal or life-threatening arterial weakness. Aortic rupture either at the aortic root and arch, or sometimes lower down the artery, are particularly characteristic. Even quite minor injury can produce dangerous vascular tearing and damage. Technical difficulties encountered in arterial repair or venous ligature are particularly worrying. The authors report the treatment of a ruptured type A aortic dissection associated with Ehlers-Danlos syndrome where the extreme fragility of the tissues and tendency to bleed posed a difficult task for the surgeon.

Adult↗
PubMed1999

The C-terminal domain of the Bordetella pertussis autotransporter BrkA forms a pore in lipid bilayer membranes.

BrkA is a 103-kDa outer membrane protein of Bordetella pertussis that mediates resistance to antibody-dependent killing by complement. It is proteolytically processed into a 73-kDa N-terminal domain and a 30-kDa C-terminal domain as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. BrkA is also a member of the autotransporter family of proteins. Translocation of the N-terminal domain of the protein across the outer membrane is hypothesized to occur through a pore formed by the C-terminal domain. To test this hypothesis, we performed black lipid bilayer experiments with purified recombinant protein. The BrkA C-terminal protein showed an average single-channel conductance of 3.0 nS in 1 M KCl. This result strongly suggests that the C-terminal autotransporter domain of BrkA is indeed capable of forming a pore.

Bacterial Outer Membrane Proteins↗
PubMed1998

Studies on the innervation of human renal allografts.

Kidneys are innervated by a plexus of nerves around the renal artery, which is disrupted by transplantation. This is a report of a comparison of the nerves in human renal allografts and normal kidneys. There were many sympathetic ganglia around normal renal arteries but none around transplanted vessels, although equal numbers of ganglia were present in hilar tissues of normal and transplanted kidneys. An immunohistological study with an antibody to synaptophysin showed that the number of synapses in transplanted ganglia was severely reduced. Immunohistological studies on allograft kidneys using antibodies to various neurofilament proteins and the Schwann cell marker S100 showed a marked reduction in neurofilament proteins shortly after transplantation with subsequent partial recovery, and a lesser reduction in S100. Renal allografts have structurally abnormal innervation but are not completely denervated.

Follow-Up Studies↗
PubMed1991

Communicating patients' esthetic needs to the dental laboratory.

A visual aid in the form of a lined transparent plastic screen is attached to an earbow type of facebow and placed on the face. The screen can be adjusted to several horizontal tilts from the horizontal aspect in a clockwise or counterclockwise direction. The screen helps the dentist visualize horizontal and vertical facial characteristics that facilitate alignment of anterior restorations. This information can be sent to the laboratory, which can interpret the data with a smaller version of the adjustable screen.

Communication↗
PubMed1981

Scanning and transmission electron microscopy of Candida albicans chlamydospores.

A simple, convenient method of growing large quantities of Candida albicans chlamydospores on a cellulose dialysis membrane has been developed. Long, narrow, cylindrical suspensor cells bearing spherical to ovoid chlamydospores were observed. Ultrastructural observations showed the chlamydospore to have a bilayered cell wall made up of an outer electron-transport primary layer and an inner electron-dense secondary layer, a large portion of the total cell volume occupied by a single large vacuole and several smaller vacuoles, and cytoplasmic organelles typical of those observed in the yeast-like cell. There are structural similarities between the region of chlamydospore-suspensor cell connection and septa observed in budding yeast-like cells.

Candida albicans↗
PubMed1980

A bilaterally balanced occlusal scheme for patients with arch width and curvature discrepancies.

A technique is described that will allow the patient maximum tooth contact in bilateral balanced occlusion without compromising esthetics or mechanics for a patient with an underdeveloped retrognathic and normal or oversized maxillae (Figs. 4 and 5). A disadvantage is maintaining the upper posterior teeth in the mold during the boil-out procedure, but this problem may be minimized with careful execution of the laboratory procedures.

Dental Arch↗
PubMed1975

Use of the remount jig as an aid in relining upper dentures.

A remount jig record is used to reposition the teeth of an upper denture reline in their original position. A face-bow record is used to position the upper edentulous cast in the correct relation to cranial planes. The impression may be developed as is done in any other impression procedure, and the repositioning can be accomplished in the laboratory with reasonable assurance that the upper denture is positioned occlusally as it was when the denture was constructed originally. This procedure relieves the dentist of the monumental task of making a reline impression and adjusting the position of the denture in one three-minute operation.

Dental Equipment↗