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Biomedical subjects

R H Riddell

Publications and source records attributed to R H Riddell.

At least 55 records · Page 3Linked to original sources
PubMed1993

Crohn's disease.

Explore the source record for details and available documents.

Biopsy↗
PubMed1993

Altered small intestinal smooth muscle function in Crohn's disease.

BACKGROUND: Studies in animals indicate that inflammation causes changes in smooth muscle contractility. Because Crohn's disease is associated with altered motility, this study investigated the contractility of intestinal muscle resected from patients with or without Crohn's disease. METHODS: The isometric contraction of muscle strips from the small bowel of 36 patients with and 24 patients without Crohn's disease was examined. RESULTS: In longitudinal muscle from patients with Crohn's disease, there was a 55% increase in maximum contraction induced by carbachol but not histamine, but there was no change in the 50% effective dose (ED50) for these agonists. In contrast, in circular muscle from patients with Crohn's disease there was a sevenfold decrease in the ED50 value for carbachol but no change in maximum contraction. There was a 2.5-fold increase in the maximum response to histamine, but no change in ED50, in circular muscle from patients with Crohn's disease. However, there was no change in KCl-induced contraction between the two groups. The carbachol responses were atropine sensitive. Histamine responses were blocked by the H1 antagonist mepyramine but were not altered by a diamine oxidase inhibitor. All responses were tetrodotoxin insensitive. CONCLUSION: These results show altered receptor-mediated contraction in small intestinal muscle in patients with Crohn's disease.

Adolescent↗
PubMed1993

Mucosal permeability to 51Cr EDTA following subclinical intestinal ischemia-reperfusion injury in the weanling rat.

The etiology of necrotizing enterocolitis (NEC) is uncertain. We have hypothesized that subclinical intestinal ischemia might result in increased mucosal permeability to intraluminal toxins or bacteria, resulting in inflammation and NEC. In order to pursue this hypothesis, we designed a series of studies to investigate whether the first assumption is correct, ie whether a subclinical ischemia-reperfusion injury (IRI) results in increased mucosal permeability. Using a model of superior mesenteric artery occlusion (SMAO) in weanling rats, we initially defined 10-minute SMAO as "subclinical" IRI (ie, 100% survival, no histological changes, and no hemodynamic instability). Mucosal permeability to a standard probe molecule (51Cr EDTA) was then measured after sham operation, or 2-minute or 10-minute SMAO. There was an early increase in permeability 30 minutes after reperfusion in the 10-minute SMAO group, which was completely reversed by 2 hours. Further studies suggested that having passed through the mucosa, the probe entered the systemic circulation via both portal venous and intestinal lymphatic routes. Subclinical intestinal IRI results in an early, reversible increase in mucosal permeability to 51Cr EDTA, which may be important in the pathogenesis of NEC. Further studies are required to fully characterize this phenomenon, and to determine the mechanisms by which it occurs.

Animals↗
PubMed1993

Can severity of symptoms be used as an outcome measure in trials of non-ulcer dyspepsia and Helicobacter pylori associated gastritis?

Most trials of non-ulcer dyspepsia (NUD) and Helicobacter pylori associated gastritis (HPAG) have not used validated methods of measuring symptoms. Three attributes are necessary for use of symptom severity scoring systems as outcome measures in clinical trials: reproducibility, responsiveness to change and validity compared to corroborating measures. The objective of this study was to establish that selected gastrointestinal symptoms recorded as a series of 5-point Likert Scales meet the 3 criteria for use as outcome measures in clinical trials. Patients with NUD (Helicobacter pylori-negative) and HPAG were studied. A preliminary assessment of 24 patients was used to select the 8 most frequently occurring and most severe symptoms. These symptoms were then scored in a further 55 patients to assess their utility as outcome measures. Observations were made at 3 time points, enrollment (T1), after 1 week with no intervention (T2) and after 4 weeks of therapy for either disease (T3). The study took place in a university hospital outpatient gastroenterology service. Symptom scores were reproducible before treatment (symptom scores at T1 and T2 were correlated), responsive (symptom scores changed after treatment between T2 and T3) and valid (symptom score changes corresponded to changes in general health status). Scoring of gastrointestinal symptom severity using 5-point Likert Scales satisfies the 3 criteria for use as outcome measures in clinical trials of NUD and HPAG.

Clinical Trials as Topic↗
PubMed1992

Distribution of collagenous colitis: utility of flexible sigmoidoscopy.

We investigated the distribution of the collagen band in 33 patients with collagenous colitis to estimate the likelihood of the disease being diagnosed in biopsy specimens from the left side of the colon, such as those obtained using flexible sigmoidoscopy. To be included in this study patients had a subepithelial collagen band greater than or equal to 10 microns, an increase in chronic inflammatory cells in the same specimen, and diarrhoea for which there was no other apparent cause. In 17 patients undergoing full colonoscopy with a thickened collagen band, collagenous colitis was frequently patchy, even though overall the thickened collagen band was almost equally distributed throughout the colon. Rectal biopsy specimens showed a normal collagen band in 73% of patients, while a thickened collagen band was found in 82% of patients in at least one specimen from the left side of the colon. Three patients had a thickened collagen band only in the caecum. In three of eight rectal biopsy specimens with a normal collagen band there was no mucosal inflammation to raise the possibility of proximal disease, although all but one specimen with a normal collagen band from the sigmoid and descending colon were inflamed. Rectal biopsy alone is therefore a relatively poor method of making the diagnosis. Flexible sigmoidoscopy with multiple biopsy specimens from several sites is a reasonable initial investigation but not sufficient to exclude collagenous colitis when based on the presence of a thickened collagen band alone. Should left sided biopsy specimens show a normal collagen band but an inflamed mucosa, total colonoscopy with multiple specimens including the caecum may be required to establish the diagnosis.

Adolescent↗
PubMed1992

Non-steroidal anti-inflammatory drugs as a possible cause of collagenous colitis: a case-control study.

The use of oral non-steroidal anti-inflammatory drugs (NSAIDs) in 31 patients with collagenous colitis and in 31 matched control patients with irritable bowel syndrome or colonic diverticular disease who had also undergone colonoscopy and biopsy was investigated. The long term use (greater than 6 months) of NSAIDs was significantly commoner in the study group (19/31) than in the control group (4/31) (p less than 0.02), even assuming the most adverse drug history in six patients in whom this could not be established. In all patients with collagenous colitis taking NSAIDs, diarrhoea followed the use of these drugs, and by a mean (SD) of 5.5 (4.4) years (range 0.5 to 15 years). In three patients with collagenous colitis, diarrhoea improved after withdrawing NSAIDs; rechallenge in one was followed by a recurrence of diarrhoea, which improved after withdrawing the drug again. It is suggested that NSAIDs may play an aetiological role in the diarrhoea and thickened collagen band in some patients with collagenous colitis.

Adult↗
PubMed1991

Yersinia enterocolitica infection with ileal perforation associated with iron overload and deferoxamine therapy.

Despite the frequency of gastrointestinal disease caused by Yersinia enterocolitica, intestinal perforation is a rare complication of this infection and to date only eight cases have been reported in the English literature. We describe a case of this unusual condition in a 17-year-old male patient with thalassemia intermedia requiring transfusion, who was also taking deferoxamine. The severity of the clinical picture is probably due to the increased virulence of Yersinia enterocolitica in the presence of deferoxamine and iron.

Adolescent↗
PubMed1991

The normal esophagus.

The diagnosis of diseases affecting the esophagus frequently depends on a knowledge of the normal anatomy and histology of the esophagus. This paper describes and relates normal esophageal gross and histological features to pathological conditions affecting the esophagus. Special attention is given to the problems of diagnosis encountered when confronted with mucosal biopsy specimens from the gastroesophageal junction.

Choristoma↗
PubMed1991

Helicobacter pylori--some what, why, and how morphologic issues.

This paper questions, and attempts to answer or speculate on, some of the morphologic questions about Helicobacter pylori in the stomach and duodenum. These include whether H. pylori can survive intact through the entire intestine, why organisms are found between rather than over the entire cells, why pedestals are relatively infrequent, possible advantages of attachment rather than a luminal existence, the nature of the inflammatory cascade from chronic inflammation to local erosion, possible mechanisms by which H. pylori causes chronic duodenitis, and the different ways that gastric metaplasia can occur in the duodenum.

Bacterial Adhesion↗
PubMed1991

Surveillance of patients with chronic ulcerative colitis. WHO Collaborating Centre for the Prevention of Colorectal Cancer.

In chronic ulcerative colitis, the object of surveillance is prevention of cancer or at least prevention of death from cancer by diagnosis at an early curable stage or by detection at a pre-malignant phase. Patients must be informed about their cancer risk as well as the limitations of endoscopic surveillance and the availability of surgical alternatives. Physicians must bear in mind the risks, benefits and costs of surveillance procedures. Patients at greatest risk of cancer for whom endoscopic surveillance is warranted are those with extensive colitis of greater than 8 years duration. Colonoscopy should be performed every 1 to 2 years at which time multiple biopsies are obtained from every 10-12 cm of normal-appearing mucosa. Targeted biopsies should also be obtained from areas where the surface appears raised as a broad-based polyp, low irregular plaque or villiform elevation, or from an unusual ulcer, particularly one with raised edges, or from a stricture. Typical inflammatory polyps need not be sampled. Colectomy is recommended in the presence of multifocal high-grade dysplasia if confirmed by an experienced pathologist. The identification of a mass lesion associated with any degree of overlying dysplasia is also a generally accepted indication for colectomy, while persistent low-grade dysplasia without a mass is somewhat more controversial. Recently introduced biomarkers may replace or supplement dysplasia in surveillance programmes as well as provide new information about malignant transformation.

Algorithms↗
PubMed1990

Screening strategies in gastrointestinal cancer.

The concept of screening is based on the notion that regular examination can reduce the mortality from gastrointestinal cancer, but there is as yet little evidence that this is the case in either Barrett's esophagus or ulcerative colitis. Screening is carried out by regular endoscopy with multiple biopsies in an attempt to detect dysplasia, which has traditionally been regarded as the end point of surveillance and the time when resection should be considered. Considerable departure from these guidelines has occurred. Attempts are increasingly being made to select patients in both of these groups who might be at particular high risk of developing dysplasia because of the presence of nuclear aneuploidy, the assumption being that these patients are at particular risk of developing dysplasia and carcinoma. However, data to support stratification at this level are unavailable. In addition, there is not good agreement as to whether surveillance is indicated at all in some groups of patients such as those with less than total colitis or short-segment Barrett's esophagus. The end point of surveillance has also been questioned, with reluctance to recommend colectomy in ulcerative colitis with the finding of low-grade dysplasia, possibly because the sampling problem is so great that it may be impossible to confirm that diagnosis on repeated endoscopy and biopsy. While better markers than dysplasia may be required to predict patients at highest risk, there are currently no marker other than the development of invasive carcinoma on which the decision to resect can be based.(ABSTRACT TRUNCATED AT 250 WORDS)

Barrett Esophagus↗
PubMed1990

The pathological diagnosis and differential diagnosis of Crohn's disease.

Crohn's disease and ulcerative colitis are distinct entities, but in 5 to 10% of patients and resected specimens, a clear separation may not be possible. The pathological diagnosis and differential diagnosis of Crohn's disease, including ulcerative colitis, indeterminate colitis and other diseases that may mimic Crohn's disease are discussed in this review, with particular emphasis on the biopsy diagnosis. It is often difficult or impossible to distinguish diversion colitis and pouchitis from recurrence of Crohn's disease; special measures need to be taken for their identification. The predisposition to cancer, and the presence of dysplasia in Crohn's disease in relation to surveillance, are also discussed.

Adult↗