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Biomedical subjects

A E Robinson

Publications and source records attributed to A E Robinson.

At least 37 records · Page 2Linked to original sources
PubMed1990

Degenerative lumbar spine disorders in gradient refocused echo axial magnetic resonance images.

The axial images of 58 lumbar disks having degenerative disorders imaged by gradient refocused echo (GRE) and spin echo (SE) magnetic resonance imaging (MRI) pulse sequences at high field strength were compared for diagnostic quality. The vacuum phenomenon, calcified disk, and bony hypertrophic changes were better demonstrated by GRE images than by SE images due to magnetic susceptibility effect. Axial GRE images are therefore useful adjuncts to SE images for effective MRI of degenerative lumbar spine disorders at high field strength.

Humans↗
PubMed1990

Variations in gastrointestinal melanoma metastases.

In 10 patients with gastrointestinal metastases from cutaneous malignant melanoma, metastases to the stomach were found in 2, the small bowel in 9, and the large bowel in 3. Gastric metastases typically appeared as target lesions. However, the morphology of secondary melanoma deposits to the small and large intestine varied significantly, target lesions being only one possible manifestation. Less common appearances of gut metastases were found in 4 patients. One presented atypically with matted loops of distal ileum resulting in prolonged stasis of barium in the affected areas. In 3 patients, infiltrative and stenotic lesions were found in the distal ileum, terminal ileum and cecum. One stenotic lesion of the distal ileum was accompanied by multiple small polypoid lesions more proximally, and the cecal lesion was ulcerated. Six of the patients presented with polypoid and, occasionally, ulcerated and multiple secondary melanoma deposits. Possible causes for variations in morphology are discussed.

Gastrointestinal Neoplasms↗
PubMed1989

Standard setting and protection of human health and safety.

Human health and safety are determined by the behavior and performance of the individual, or of a piece of equipment, under the prevailing conditions. Setting health or safety standards, which will define a set of conditions to provide protection, requires consideration of many factors, including the level of protection required and the collection and assessment of factual information. The purpose of the paper is to identify and discuss the elements of the standard-setting process and the major issues likely to be associated with it. Occupational exposure values and other initiatives to provide protection of human health from the potential effects of chemicals in Canada are reviewed in the context of recent initiatives and current pressures for change.

Accident Prevention↗
PubMed1988

Giant aneurysms of bilateral internal carotid arteries in a child.

Aneurysms in the petrous or cavernous portion of the internal carotid artery in childhood are extremely rare. Only two such cases have been previously reported. We present a case of bilateral giant intrapetrous aneurysms in a young female. CT was especially helpful in evaluating the absolute size of these aneurysms. This case is unique in that we demonstrated the temporal evolution of internal carotid aneurysms on follow-up angiography.

Carotid Artery, Internal↗
PubMed1988

Breast neoplasms: duplex sonographic imaging as an adjunct in diagnosis.

Sonographic breast imaging has been useful in the differentiation of cystic from solid masses. It has also been helpful in the characterization of palpable breast masses in the absence of corresponding abnormalities. The authors undertook a prospective study that incorporated pulsed Doppler analysis into sonographic real-time imaging of solid breast masses. Thirty-eight patients were examined. In 12 of the patients there were positive Doppler signals, while in 26 patients there were no Doppler signals. The 12 patients showing positive Doppler signals proved to have infiltrating ductal carcinoma, while the 26 patients with negative Doppler signals proved to have benign breast disorders. Pulsed Doppler analysis as a supplement to sonographic real-time imaging shows promise for the identification of breast carcinoma.

Adult↗
PubMed1987

Effect of cross linkers on the bacteriorhodopsin photocycle.

A general behavior of bacteriorhodopsin in purple membranes from Halobacterium halobium has been observed upon modification resulting in cross-linking of carboxyl and lysine groups. The rise of the M-intermediate contained two components with approximately 50-50% intensity; its decay showed three components with approximately 25-50-25% intensity respectively in a pH range of 5-9. The significance of these remarkably similar data with respect to the proton translocation mechanism in bacteriorhodopsin is that chemical modification allows us to conclude that disturbing parts of the hypothetical "proton conducting chain" does not inhibit proton translocation.

Bacteriorhodopsins↗
PubMed1987

Eosinophilic granuloma of the cervical spine without vertebrae plana.

A case of eosinophilic granuloma of the cervical spine is described. Cervical radiography and computed tomography demonstrated destruction of pedicles and posterior portions of the neural arch. Vertebral body heights were essentially preserved and the importance of this finding is underscored. Computed tomography played an important role in evaluating the extent of this disease.

Cervical Vertebrae↗
PubMed1986

Radiation dose reduction in pediatric CT.

The relationship between image noise and radiation dose was investigated in computed tomography (CT) images of a pediatric abdomen phantom. A protocol which provided a minimum absorbed dose consistent with acceptable image noise criteria was determined for a fourth generation CT scanner. It was found that pediatric abdominal CT scans could maintain diagnostic quality with at least a 50% reduction in dose from the manufacturers' suggested protocol.

Child↗
PubMed1986

Aggregation and proton release of purple and white membranes following cleavage of the carboxyl-terminal tail of bacteriorhodopsin.

Our results indicate that the previously reported decrease in proton release by proteolyzed purple membrane sheets was due merely to the aggregation state of these preparations and not to the loss of the carboxyl-terminal tail. Changes in H+/M412 ratios obtained for purple and white membrane preparations correlate with the measured aggregation. White membrane preparations consistently exhibit H+/M412 ratios more than twice those measured for native purple membranes under the same conditions. Quasi-elastic light scattering was used to characterize the size of isolated purple and white membrane sheets before and after proteolysis. The results clearly show that native purple membrane preparations are larger in size than would be expected and that, following trypsin treatment, they are on average more than an order of magnitude larger. Negative staining electron microscopy showed that the purple membrane became aggregated in stacked arrays. Bleaching and reconstitution with retinal also affect aggregation, but iodination or nitration of purple membrane does not affect the measured size. The average size of white membranes is smaller; this is consistent with results of electron microscopy and the size increase is much less than that of purple membranes following trypsin treatment. No size change occurs with retinal reconstitution. In aggregated purple membrane preparations, protons and other cations are unable to exchange freely with the aqueous medium, explaining why proteolysis lowers the proton release from purple membrane sheets in suspension.

Bacteriorhodopsins↗
PubMed1986

Flank mass and pain in a 72-year-old man.

This patient had retroperitoneal multiseptated masses, which extensively invaded the right flank and thigh musculature. The radiologic, pathologic, and clinical findings were consistent with a retroperitoneal pseudomyxoma from an appendiceal mucocele.

Aged↗
PubMed1985

A study of one of the iron-sulphur clusters in oxidized hydrogenase from Megasphaera elsdenii by magnetic-circular-dichroism spectroscopy.

The m.c.d. spectrum of the oxidized state of hydrogenase from Megasphaera elsdenii has been measured at liquid-helium temperatures. This oxidation state of the enzyme displays a characteristic rhombic e.p.r. signal with g-values of 2.101, 2.052 and 2.005 assigned previously to a [4Fe-4S]3+ cluster as in oxidized HiPIP (high-potential iron-sulphur protein) [Van Dijk, Grande, Mayhew & Veeger (1980) Eur. J. Biochem. 107, 251-261]. The low-temperature m.c.d. spectrum shows no features attributable to an oxidized four-iron cluster of the HiPIP type, but does reveal broad, positive peaks at 460 and 730 nm, which magnetize in a manner untypical of a spin S = 1/2 cluster with g-values close to 2. The m.c.d. spectrum is most closely similar to that of dye-oxidized P-clusters known in the enzyme nitrogenase. It is therefore proposed that the rhombic e.p.r. spectrum at a g-value close to 2 arises from an m.c.d.-silent radical species that may be related chemically to the cysteine persulphide species, RS-S., recently found in the hexacyanoferrate-oxidized seven-iron ferredoxin of Azotobacter vinelandii [Morgan, Stephens, Devlin, Stout, Melis & Burgess (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 1931-1935].

Circular Dichroism↗