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Biomedical subjects

R H Riddell

Publications and source records attributed to R H Riddell.

144 records · Page 8Linked to original sources
PubMed1970

Trimethoprim as an additional selective agent in media for the isolation of N. gonorrhoeae.

The incorporation of trimethoprim into existing selective media using either saponin-lysed blood agar or chocolate agar as the base is suggested for the routine isolation of the gonococcus. The principal advantage over other selective media is the inhibition of Proteus mirabilis and other commensal organisms as a consequence of which multiple swabs can be plated out onto a single selective plate irrespective of source, while the recovery rate of the gonococcus from these specimens is increased. The relative merits of both basic media are briefly discussed.

Agar↗
PubMedDate not supplied

Grading of dysplasia.

Lethal carcinomas are still found inadvertently in patients under surveillance; some may not be preceded by conventional dysplasia. However, there is a survival advantage for cancers detected endoscopically rather than symptomatically, and, therefore, by preventing them by colectomy when dysplasia first becomes apparent. It may, therefore, be unnecessary to grade dysplasia when found, for if unequivocally present, then immediate consideration of colectomy is appropriate. It is unreasonable to expect colonoscopists to rebiopsy what might be a minute patch of dysplasia that has no distinguishing features endoscopically. Aneuploidy deserves consideration as a potential marker of patients at particular risk of developing dysplasia, who might undergo more frequent colonoscopy and biopsies than those without the presence of aneuploidy. There is still considerable interobserver variability in the grading of dysplasia by pathologists; part of this may be because grading occurs around a mean, the width of the tails of this distribution curve determining interobserver variation.

Colitis, Ulcerative↗
PubMedDate not supplied

Polyps and polypectomy surveillance--role of the histopathologist.

The traditional roles of the pathologist are those of diagnostician, and being able to communicate these diagnoses back to the clinician in a clear unambiguous form so that subsequent therapy can be planned. Important findings may require more direct communication, particularly when the implications involve a choice between therapeutic options. Some diagnoses have implications that require an educational role for the pathologist; these in turn may evolve into a research role, based on clinico-pathological correlation, active basic science research or simply supplying tissue for research. Clinicians must also be aware that the same biopsy can be interpreted in numerous ways, depending upon the clinical situation.

Colonic Polyps↗
PubMedDate not supplied

A study to examine agreement between endoscopy and histology for the diagnosis of columnar lined (Barrett's) esophagus.

Eleven subjects with a previous diagnosis of columnar lined esophagus and 12 control patients underwent esophagogastroduodenoscopy, including vital staining with Lugol's iodine and biopsy. Histology in 47 of 48 biopsies from controls agreed with endoscopic findings, and no patient had a columnar lined esophagus. Of 60 biopsies taken from study patients, the endoscopic appearance in 8 (13%) was not consistent with the histology. Good agreement was demonstrated between endoscopy and histology (kappa = 0.72). Compared with histology as the reference measure, the sensitivity, specificity, and accuracy of endoscopy were 89%, 93%, and 91%, respectively.

Adult↗
PubMedDate not supplied

Evaluation of salivary antibodies to detect infection with Helicobacter pylori.

Helicobacter pylori infection is an important cause of peptic ulcer disease and chronic gastritis. Infection with this bacterium stimulates the production of immunoglobulin (Ig) G antibody. Salivary IgG antibody tests to detect H pylori infection offer a convenient and noninvasive method of diagnosis. To evaluate an IgG salivary antibody kit, saliva was collected from 157 out-patients with dyspepsia referred for endoscopy to a tertiary centre. A salivary IgG ELISA antibody assay was performed using the Helisal Helicobacter pylori (IgG) assay kit, and at least four gastric biopsies were obtained. H pylori infection was confirmed by demonstration of the organism on Warthin-Starry silver stain (sensitivity 85%, specificity 55%). The prevalence of infection with H pylori was 30%. When the analysis was redone, excluding those treated with eradication therapy, the results were similar (sensitivity 86%, specificity 58%). The positive predictive value of the assay was 45% and the negative predictive value was 90%. Despite the ease of sampling, the assay used has limited diagnostic utility, lacking the predictive value to indicate which patients referred with dyspeptic symptoms to a tertiary care setting are infected with H pylori.

Adolescent↗
PubMedDate not supplied

East meets West: what is early cancer?

It has become increasingly apparent that the Japanese and Western systems of classifying dysplasia and carcinoma in the gastrointestinal tract are not the same. The implication of these differences is that in an article in a Western journal on gastrointestinal 'cancer' originating from Japan, it is often impossible to repeat the study to confirm or refute it because of these differences in definitions. 'Carcinoma' is diagnosed in Japan by virtue of its structural and cytological features but by invasion in the Western system. Adenoma does not mean a dysplastic lump in the Japanese system (although it can), but in most cases is similar to low grade dysplasia irrespective of the macroscopic and/or endoscopic appearances (hence flat and depressed adenomas in the Japanese system); however, most examples of high grade dysplasia in the Western system, as well as some low grade dysplasia, are 'cancer' in the Japanese system. Conversely, both have conceptual areas that are useful in the other's system.

Adenoma↗
PubMedDate not supplied

Apatite determination and distribution in an early stage of gallbladder calcification.

This study is concerned with the nature and distribution of mineral in the gallbladder of a patient with chronic cholecystitis. Light and electron microscopic imaging revealed the mineral to be in the epithelial cells of the mucosa and fibroblasts of the submucosa. In the epithelial cells at the early stages of deposition, mineral was located in the nuclei and throughout the cytoplasm in association with interdigitating cell processes and apical microvilli but was absent in mitochondria. Elemental and electron diffraction analyses indicated the mineral inclusions to be apatite in nature.

Adult↗
PubMedDate not supplied

Accumulation of mast cells and macrophages in focal active gastritis of patients with Crohn's disease.

BACKGROUND/AIMS: Recent studies have shown that focal active gastritis seems to be the typical gastric pathology in Crohn's disease. The aim of this study was to compare the incidence of focal active gastritis, Helicobacter pylori infection and distribution of gastric mast cells and macrophages in patients with Crohn's disease, ulcerative colitis and H. pylori gastritis without inflammatory bowel disease. METHODOLOGY: Patients with histologically confirmed Crohn's disease (n = 25) or ulcerative colitis (n = 25) and control patients without inflammatory bowel disease (n = 25) were included in this study. Biopsy specimens were obtained from the antrum and corpus of each patient, and stained with hematoxylin and eosin and immunostained using antibodies to tryptase (AA1) and CD68. The number of mast cells and macrophages located in the lamina propria was determined. RESULTS: Focal active gastritis was detected in 54% of H. pylori-negative patients with Crohn's disease, but it was not found in patients with ulcerative colitis nor in the control group. The density of mast cells and macrophages in the lamina propria of H. pylori-positive patients was significantly higher than in H. pylori-negative patients in all groups. In the Crohn's disease group, the number of mast cells (antrum; 83 +/- 11, body; 89 +/- 11/mm2) and macrophages (antrum; 94 +/- 22, body; 92 +/- 17/mm2) in the lamina propria of H. pylori-negative patients with focal active gastritis was halfway between that in H. pylori-positive and H. pylori-negative patients. In focal active gastritis, mast cells accumulated at the border of focal active gastritis, whereas macrophages accumulated in the center of such lesions. CONCLUSIONS: Our findings indicated that the diagnosis of focal active gastritis, using immunostain for mast cells and macrophages, is the histological hallmark of gastric Crohn's disease. Macrophages might be associated with the formation of focal active gastritis in patients with Crohn's disease.

Adult↗