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Biomedical subjects

A Walker

Publications and source records attributed to A Walker.

At least 325 records · Page 18Linked to original sources
PubMed1977

Eye dose measurements using conventional and rare-earth screens during tomography of the para-nasal sinuses.

Eye dose measurements have been performed when using medium speed conventional and rare-earth screen-film combinations during tomography of the para-nasal sinuses. The measurements show that using conventional intensifying screens with the A.P. view a total eye dose of about 20 rad may be given during an examination. This eye dose can be reduced by 98% using the P.A. position. If rare-earth screen/film combinations are employed the eye dose measured in the A.P. view was reduced by 75% of that obtained with conventional screens without detectable loss of image quality. A total eye dose reduction of about 99.5% was measured in the P.A. view with the rare-earth systems.

Ear, Middle↗
PubMed1977

Management of chronic glaucoma with pilocarpine Ocuserts.

This paper presents a clinical assessment of the Ocusert pilocarpine therapeutic system in 22 patients. Severe patients were 'wearing failures' and one was a 'therapeutic failure'. In the remaining patients intraocular pressure were controlled satisfactorily by a small daily dose of pilocarpine and there was relief from the burden of regular drop administration and the transient myopia which follows each instillation. This study confirms a place for the 'Ocusert' system in the management of some patients with chronic glaucoma.

Adult↗
PubMed1976

Inducible, error-free DNA Repair in tsl recA mutants of E. coli.

Host of cell reactivation and UV reactivation and mutagenesis of UV-irradiated phage mu were measured in tsl recAplus and tsl recA host mutants. Host cell reactivation was slightly more efficient in the tsl recA strain. Phage was UV-reactivated in the tsl recA strain with about one-half the efficiency of that in the wild type strain, but there was no corresponding mutagenesis of phage. UV-reactivation was also slightly lower and mutagenesis several-fold lower than normal in the tsl recAplus strain. To account for these observations, we propose that there is an inducible, error-free pathway of DNA repair in E. coli that competes with error-prone repair for repair of phage lesions.

Coliphages↗
PubMed1976

The hydraulic impedance of the lower limb: its relevance to the success of bypass operations for occlusion of the superficial femoral artery.

Simultaneous measurements of pressure and flow waves were made in the course of 25 femoropopliteal bypass operations. From these measurements the the hydraulic impedance of the arterial system in the lower limb was calculated. The values obtained were correlated with the results of the operations. Although reconstruction reduced the impedance we were unable to predict accurately the probable result of the operation on the basis of these measurements. The results suggest that success is more closely related to a good collateral circulation than to "run off".

Arterial Occlusive Diseases↗
PubMed1976

Altered viscosity and yield stress in patients with abdominal malignancy: relationship to deep vein thrombosis.

Twenty-eight patients undergoing laparotomy were studied. Blood viscosity at both high and low rates of shear and a yield stress index were measured preoperatively and correlated with the incidence of post-operative deep vein thrombosis (DVT). There was a correlation between a raised index of yield stress and the incidence of DVT. Patients with cancer had a very high incidence of postoperative DVT and a high index of yield stress.

Abdominal Neoplasms↗
PubMed1976

The effect of an infusion of low molecular weight dextran on peripheral resistance in patients with arteriosclerosis.

Low molecular weight dextran is frequently given to improve the flow of blood to the periphery, but its mode of action is uncertain. We measured the effect of an infusion of 500 ml of Dextran 40 on the peripheral resistance in 12 patients undergoing reconstructive surgery for atherosclerotic occlusion of the superficial femoral artery. After the infusion, values of packed cell volume and blood viscosity indicated haemodilution. There was a consistent increase in mean flow and a fall in peripheral resistance. There was no correlation between change in viscosity and change in peripheral resistance, but there was a good correlation between the percentage change in resistance and the initial resistance. This suggests that the increase in flow of blood was due to reflex vasodilatation rather than to any reduction in viscosity.

Arteriosclerosis↗
PubMed1975

Immunology of sarcoidosis.

The cardinal immunologic changes in sarcoidosis consist of depression of delayed-type hypersensitivity, hyperreactive circulating antibody responses and the Kveim-Siltzbach skin test phenomenon. Depression of delayed-type hypersensitivity is demonstrated by skin tests using tuberculin, mumps, pertussis, trichophytin, oidiomycin, dinitrochlorobenzene and Californian keyhole limpet hemocyanin. The cultured lymphocytes from patients with depression of delayed-type hypersensitivity react poorly to phytohemagglutinin, and there is a close correlation between anergy of lymphocytes in culture and by cutaneous anergy. In vivo cutaneous anergy mirrors in vitro cellular hyporeactivity. Other technics used to expose immunologic defects in peripheral lymphocytes of patients with sarcoidosis include tests of T and B cell function, rosetie formation and migration inhibition. Whereas there is cutaneous anergy and impaired cellular immunity in patients with sarcoidosis, the reverse holds for circulating factors. There are increased circulating immunoglobulin levels, increased circulating antibody levels to Epstein-Barr, herpes simplex, rubella, measles and parainfluenza viruses, increase antibody response to mismatched blood and occasional false-positive Wassermann reactions, but there is no increase in circulating autoan tibodies. There is no evidence that patients with sarcoidosis belong predominantly to any particular histocompatibility locus. Worldwide figures for the Kveim-Siltzbach skin test are presented. They provide evidence of its specificity in various international series. The causes of nonspecific reactions are discussed.

Antibodies, Viral↗