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Biomedical subjects

G D Webster

Publications and source records attributed to G D Webster.

At least 127 records · Page 7Linked to original sources
PubMed1980

Importance of routine vascular nephrotomography in excretory urography.

The rapid intravenous injection of a large bolus of contrast medium produces a vascular as well as a tubular nephrogram. They are additive but the vascular phase is early, intense, and brief whereas the tubular phase is less intense but more prolonged. The addition of tomography during either phase improves visualization of the renal parenchyma and its outline. A comparison study of tomography during the vascular phase (vascular nephrotomography) with that at five minutes demonstrated the superiority of the former. Our technique, data, and illustrative case abstracts are presented.

Adenocarcinoma↗
PubMed1980

The evaluation of bladder neck dysfunction.

Bladder neck dysfunction has been evaluated in 16 male patients. The efficacy of the traditional investigative methods for this entity is questionable and the value of video-urodynamics for definitive diagnosis is presented. The ability of the condition to masquerade as prostatis is apparent and treatment by unilateral bladder neck incision is proposed.

Diagnosis, Differential↗
PubMed1980

Accuracy of radionuclide imaging in distinguishing renal masses from normal variants.

To determine the accuracy of scintigraphy in distinguishing true renal masses from normal variants, 40 patients with excretory urographic findings indicating a possible, but not definite, mass lesion were studied. Scintigraphy correctly identified 17 true masses and 17 normal variants. Four false positive and two false negative results were obtained.

Abscess↗
PubMed1979

Traumatic rupture of the female urethra.

The clinical course of 4 female patients with complete traumatic rupture of the urethra was evaluated in an effort to propose guide lines for the investigation and initial management of this unusual injury. Treatment modalities are determined by the level of urethral injury and the subsequent effect on continence. We recommend a retropubic approach for bladder neck injuries, a transvaginal approach for proximal urethral ruptures with reanastomosis over a stenting catheter and acceptance of a hypospadiac neomeatus for distal urethral ruptures.

Adult↗
PubMed1978

Affinity chromatography of H+-translocating adenosine triphosphatase isolated by chloroform extraction of Rhodospirillum rubrum chromatophores. Modification of binding affinity by divalent cations and activating anions.

1. ATPase isolated from Rhodospirillum rubrum by chloroform extraction and purified by gel filtration or affinity chromatography shows three bands (alpha, beta and gamma) upon electrophoresis in sodium dodecyl sulphate. 2. Ca2+-ATPase activity of the preparation is inhibited by aurovertin and efrapeptin but not by oligomycin. Activity may be inhibited by treatment with 4-chloro-7-nitrobenzofurazan and subsequently restored by dithiothreitol. 3. The enzyme fails to reconstitute photophosphorylation in chromatophores depleted of ATPase by sonic irradiation. 4. Most of the active protein from the crude chloroform extract binds to an affinity chromatography column bearing an immobilised ADP analogue but not to a column bearing immobilised pyrophosphate. 5. In the absence of divalent cations, a component with a very high specific activity for Ca2+-ATPase is eluted from the column by 1.6 mM ATP. This protein migrates asa single band on 5% polyacrylamide gel electrophoresis and only possesses three subunits. At 12 mM ATP an inactive protein is eluted which does not run on acid or alkali polyacrylamide gels and shows a complex subunit structure. 6. ATPase preparations prepared by acetone extraction or by sonic irradiation of chromatophores may also be purified 10-fold by affinity chromatography. 7. The inclusion of 5 mM MgCl2 or CaCl2 during affinity chromatography of chloroform ATPase increases the capacity of the column for the enzyme and demands a higher eluting concentration of ATP. 8. When the enzyme is more than 90% inhibited by efrapeptin or 4-chloro-7-nitrobenzofurazan, the binding characteristics of the enzyme are not affected. 9. 10 mM Na2SO3, which greatly stimulates the Ca2+- and Mg2+-dependent ATPase activity of the enzyme and increases Ki (ADP) for Ca2+-ATPase from 50 to 850 micron, prevents binding to the affinity column. Binding may be restored by the addition of divalent cations. 10. Na2SO3 increases the rate of ATP hydrolysis, ATP-driven H+ translocation and ATP-driven transhydrogenase in chromatophores. 11. It is proposed that anions such as sulphite convert the chromatophore ATPase into a form which is a more efficient energy transducer.

Adenosine Triphosphatases↗
PubMed1975

The American Board of Internal Medicine recertification examination: process and results.

On 26 October 1974, 3356 diplomates of the American Board of Internal Medicine (ABIM) took a 1-day written examination for recertification consisting of multiple-choice, matching, and true-false questions derived from the American College of Physicians' Medical Knowledge Self-Assessment Program III and the ABIM Certifying Examination pool. The passing score was set by using a normative standard applied to a reference group of internists practicing general internal medicine who had had 2 or more years of residency training completed between the years 1949 and 1958. The passing score represented approximately 63% correct answers. The failure rate for the total number of examinees was 4.3%. Mean score of examinees showed an inverse relation with age but relatively slight differences when analyzed according to the degree of subspecialization, practice setting, hospital affiliation, or size of patient community.

Achievement↗