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Biomedical subjects

W W Ward

Publications and source records attributed to W W Ward.

34 records · Page 2Linked to original sources
PubMed1981

Aortic cusp involvement causing severe aortic regurgitation in a case of relapsing polychondritis.

A case with relapsing polychondritis is described where primary involvement of the aortic valve cusps produced severe aortic regurgitation requiring valve replacement. An aneurysmal dilatation of the ascending aorta developing later led to disruption of the prosthesis requiring re-operation. Superior vena caval obstruction, an abdominal aortic aneurysm which ruptured and required resection, and obstructive lesions in common iliac arteries, presumably the result of the same process that involved the aorta and the cartilaginous structures, were also seen.

Adult↗
PubMed1977

Jejunal diverticulitis.

Two patients with jejunal diverticulitis are presented. Each demonstrated a wide spectrum of clinical and radiographic findings over several years. Radiographic abnormalities including incomplete jejunal obstruction, an omental mass displacing jejunal loops, leakage of barium into adjacent mesenteric abscess, and extrinsic serosal changes involving the transverse colon have permitted a correce preoperative diagnosis in each patient.

Aged↗
PubMed1975

Renilla luciferin as the substrate for calcium induced photoprotein bioluminescence. Assignment of luciferin tautomers in aequorin and mnemiopsin.

A study was made of the effects of pH and protic and aprotic solvents on the spectral properties of Renilla (sea pansy) luciferin and a number of its analogs. The results have made possible the assignment of two tautomeric forms of Renilla luciferin, one which absorbs maximally at 435 nm and another which exhibits an absorption maximum at 454 nm. Furthermore the results provide an explanation for the visible absorption characteristics of the photoproteins aequorin (lambda-max 454 nm) and mnemiopsin (lambda-max 435 nm). In addition a Renilla-like luciferin can be extracted from both of these photoproteins. This luciferin produces light with Renilla luciferase, at a rate dependent upon the concentration of dissolved oxygen, and in other respects is indistinguishable from Renilla luciferin in this bioluminescent reaction. The results suggest that the native chromophore in both photoproteins is Renilla luciferin (or a nearly identical derivative). The results also suggest that a hydroperoxide intermediate probably exists in photoproteins, on energetic grounds, and to account for the oxygen concentration independency of the rate of photoprotein reactions. This hydroperoxide may be attached initially to an amino-acid side chain (possibly indolyl-OOH, imidazoyl-OOH, or -SOOH) rather than to the luciferin chromophore.

Aequorin↗
PubMed1975

Extraction of Renilla-type luciferin from the calcium-activated photoproteins aequorin, mnemiopsin, and berovin.

Photoproteins, which emit light in an oxygen-independent intramolecular reaction initiated by calcium ions, have been isolated from several bioluminescent organisms, including the hydrozoan jellyfish Aequorea and the ctenophore Mnemiopsis. The system of a related anthozoan coelenterate, the sea pansy Renilla reniformis, however, is oxygen dependent, requiring two organic components, luciferin and luciferase. Previously published indirect evidence indicates that photoproteins may contain a Renilla-type luciferin. We have now extracted in high yield a Renilla-type luciferin from three photoproteins, aequorin (45% yield), mnemiopsin (98% yield), and berovin (85% yield). Photoprotein luciferin, released from the holoprotein by mercaptoethanol treatment and separated from apo-photoprotein by gel filtration, no longer responds to calcium but now requires luciferase and O2 for light production. Photoprotein luciferin is identical to Renilla luciferin with respect to reaction kinetics and bioluminescence spectral distribution. In view of these results, the generally accepted hypothesis that the photoprotein chromophore is a protein-stabilized hydroperoxide of luciferin must be modified. We believe, instead, that the chromophore is free luciferin and that oxygen is bound as an oxygenated derivative of an amino-acid side chain of the protein. We propose the general term "coelenterate luciferin" to describe the light-producing chromophore from all bioluminescent coelenterates and ctenophores.

Aequorin↗