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Biomedical subjects

D J Watson

Publications and source records attributed to D J Watson.

At least 55 records · Page 3Linked to original sources
PubMed1987

Isotope-dilution assay for urinary methylmalonic acid in the diagnosis of vitamin B12 deficiency. A prospective clinical evaluation.

Vitamin B12 deficiency is a frequently considered diagnosis for which there is no single, commonly available and accurate test. A urinary methylmalonic acid assay using gas chromatography-mass spectrometry has been proposed as the preferred test. We reviewed vitamin B12 assays on 1599 consecutive patients and prospectively studied all patients with low serum B12 levels (n = 75) and a random sample of patients with normal levels (n = 68). Of 96 evaluable patients, 7 had clinical deficiency. All 7 deficient patients had urinary methylmalonic acid levels greater than 5 micrograms/mg creatine (sensitivity, 100%; confidence interval, 65% to 100%). Of the 89 patients who were not clinically deficient, 88 had urinary methylmalonic acid levels less than or equal to 5 micrograms/mg creatinine (specificity, 99%). The overall test accuracy in this population was 99%. If the high sensitivity and specificity of the gas chromatography-mass spectrometry assay for urinary methylmalonic acid is supported by other clinical studies, the methylmalonic acid assay may become the reference standard for the diagnosis of vitamin B12 deficiency.

Aged↗
PubMed1986

The effect on the ear of late closure of the cleft hard palate.

Thirty-three patients with cleft palate are reviewed. The late effects on the ear of delayed closure of the hard palate after early soft palate repair are compared with the results of simultaneous early closure of both hard and soft palate clefts. Delayed closure of the hard palate does not affect the incidence of otitis media, the number of insertions of ventilation tubes or the findings on otoscopy. The prevalence of sensorineural hearing loss is significantly raised by late closure of the hard palate. The reason for this is unknown.

Adolescent↗
PubMed1983

Large-cell calcifying sertoli cell tumor of the testis. An ultrastructural, immunocytochemical, and biochemical study.

This report describes the ultrastructural and hormonal characteristics of the recently described large-cell calcifying Sertoli cell tumor of the testis, a rare subtype of pure Sertoli cell tumor. The ultrastructural findings showed similarity to normal Sertoli cells, pure Sertoli cell tumors, Sertoli cells in azoospermic human testes, and the Sertoli cell component of Sertoli-Leydig cell tumors. Ultrastructure indicated features common to steroid-producing cells. Testosterone and estradiol were demonstrated in the tumor by immunocytochemical and biochemical methods.

Basement Membrane↗
PubMed1976

The influence of gastric distension and the duodenal infusate on the pattern of stomach (abomasal) emptying in the preruminant calf.

1. In the conscious calf it is possible to use duodenal re-entrant cannulae to measure the output of a gastric test meal directly from the proximal cannula placed near the pylorus. At the same time the duodenum can be isolated from the stomach and maintained under constant stimulus by a continual infusion at regulated pressure, volume and temperature into the distal cannula. 2. Under these experimental conditions the pattern of gastric emptying is exponential in form. Thus direct recording of gastric emptying validates indirect methods, such as the serial test meal, where volume markers are used. It appears likely that the exponential pattern of gastric emptying is common to man, dog, cat and calf. 3. When the isolated duodenum was infused with water, the exponential pattern of gastric emptying was maintained even when the volume of meal instilled was increased substantially from 1 to 41. 4. Distension of the stomach by larger test meals did not affect the relative rate of emptying so that the half-time of emptying of all meals was about the same. 5. When the isolated duodenum was infused with 0-06 M-HCl gastric emptying of the smaller meals was almost completely inhibited. The inhibition of gastric evacuation was accompanied by inhibition of the gastric e.m.g. 6. Infusion of the duodenum with acid also produced marked, but not complete, inhibition of emptying the larger test meals but the distension produced by the larger meals appeared to partially overcome the inhibitory effect of the acid duodenal infusate so that a small efflux occurred from the stomach. This small efflux was usually associated with some slight degree of gastric e.m.g. activity. 7. We are still investigating the mechanisms whereby the duodenum affects gastric emptying, but it is clearly demonstrable from our present results that the inhibitory effects of acid duodenal infusate are sufficiently powerful to overcome the forces, both physical and reflex, which normally aid gastric evacuation.

Abomasum↗