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Biomedical subjects

R L Barclay

Publications and source records attributed to R L Barclay.

9 recordsLinked to original sources
PubMed2001

Ulcerative colitis of the appendix ('ulcerative appendicitis') mimicking acute appendicitis.

Appendiceal involvement in ulcerative colitis may occur in the setting of either diffuse or distal disease, and is usually diagnosed incidentally at the time of proctocolectomy. The present patient had a rare case of 'ulcerative appendicitis' occurring on a background of clinically quiescent ulcerative colitis, and presented with the signs and symptoms of acute appendicitis.

Acute Disease↗
PubMed1997

Esophagitis as the outcome of progressive failures of the defensive repertoire.

Pre-epithelial defences include the coordinated actions of the lower esophageal sphincter and the esophageal muscles, which minimize reflux of gastric contents and promote clearance of refluxed material. The esophageal epithelium also possesses innate resistance to luminal damaging agents and may be protected luminally by a mucus or 'mucus bicarbonate' barrier and possibly a layer of hydrophobic surfactants. These components are derived from submucosal glands located in the submucosal connective tissue and from salivary secretions that may bind to the esophageal surface. Epithelial defences include the glycocalyx, permeability properties of the epithelial cell plasma membrane, junctional barriers to proton permeation through the paracellular pathway and ion transport processes for regulation of intracellular pH. Subepithelial defences involve mainly regulation of blood supply via responses of nerves, mast cells and blood vessels to influxing protons. Although the epithelium can withstand prolonged exposure to physiologically relevant concentrations of acid, the presence of pepsin or bile salts may overcome the permeability barrier, which probably resides in the superficial layers of epithelial cells. Focal destruction of these cells allows access of luminal acid and other aggressive agents to the vulnerable basolateral cell membranes and to the submucosa. The result is lesion production, although an efflux of alkaline plasma may protect the underlying submucosa and allow healing. Salivary-derived epidermal growth factor (EGF) is present in the luminal fluid, and lesion development may also provide access of EGF to receptors within the epithelium and in the underlying vasculature. Accelerated cell proliferation would then contribute to healing. Inflammation and healing should also be viewed as defensive responses, as can the development of Barrett's esophagus, in which the stratified squamous epithelium is replaced by a potentially acid-resistant columnar epithelium. Chronic inflammation and esophagitis only result when this multilayered set of defences is overcome. The challenge for research is to identify those components of the defensive repertoire that are defective in individuals who suffer from chronic esophagitis.

Animals↗
PubMed1995

Morphological evidence of mast cell degranulation in an animal model of acid-induced esophageal mucosal injury.

In previous studies we have demonstrated that microvascular permeability increases early in the course of experimental acid-induced esophageal mucosal injury. This is associated with an increase in the intraluminal appearance of histamine, suggesting a possible role for mast cells in this form of injury. In the present study, quantitative analysis of esophageal mast cells was undertaken using both light and electron microscopy in opossums undergoing intraluminal esophageal acid perfusion or normal saline control perfusion. Light microscopy showed that animals perfused with either 50 or 100 mM hydrochloric acid had an approximate 50% decrease in the number of stainable esophageal mast cells. Stereologic analysis of electron micrographs revealed that within the mucosa, the mean area of the mast cells as well as nuclear area and area of intact granules were also significantly reduced in acid perfused animals. Taken together these quantitative morphological analyses suggest that intraluminal acid exposure is associated with degranulation and/or lysis of esophageal mast cells and that released mediators from esophageal mast cells may play a role in the pathophysiology of reflux esophagitis.

Animals↗
PubMed1976

Aspects of the normal psychology of pregnancy: the midtrimester.

In this study of nonpregnant women were compared with pregnant women. A set of feelings and attitudes along with questions relevant to the anatomy and physiology of parturition were the measures of comparison. The pregnant women and the nonpregnant women had almost identical feelings and attitudes. There were, however, three exceptions to this general condordance. They were: (1) the nonpregnant women's regard of pregnancy as a depressive and withdrawing experience, (2) a greater fear for the fetus among the nonpregnant women, and (3) higher scores on a pregnancy information inventory among the pregnant women.

Adjustment Disorders↗
PubMed1975

Total calcium content of skeletal muscle isolated from humans and pigs susceptible to malignant hyperthermia.

Total calcium content of both human and porcine MHS skeletal muscle is significantly less than normal. This data is consistent with the concept that some organelle (probably the sarcoplasmic reticulum, the mitochondrion or even the sarcolemma) within the MHS muscle stores less than normal amounts of calcium. The large variability between muscle specimens rules out measurement of total calcium content of skeletal muscle as a routine diagnostic test for malignant hyperthermia susceptibility.

Animals↗