Search PubMed⌕ Search

Biomedical subjects

D G Thompson

Publications and source records attributed to D G Thompson.

At least 127 records · Page 7Linked to original sources
PubMed1987

Action of centrally mediated autonomic stimulation on human upper gastrointestinal transit: a comparative study of two stimuli.

Two well established experimental stressors, hand immersion in cold water, and mental stimulation with dichotomous listening, were applied to 37 normal subjects after the ingestion of a standard meal. Orocaecal transit was measured by serial exhaled breath hydrogen sampling. Cold water significantly delayed transit compared with warm water control (warm water 71.8 +/- 3.6 mins v cold water 93.2 +/- 5.7 mins p less than 0.01), with significant rises in blood pressure pulse rate perceived discomfort and plasma catecholamines. In contrast mental stimulation was unaccompanied by any change in transit (control; 67.4 +/- 4.7 v test 64.3 +/- 5.3 mins p greater than 0.1) despite a significant rise in pulse rate, skin conductance and plasma catecholamines. Repeated cold water immersion studies in eight individuals produced consistent orocaecal transit and autonomic responses, whereas mental stimulation showed reduced autonomic responses on repeat testing, suggesting that tolerance to the stimulus had occurred. The results of these studies show stimulus specific gastrointestinal response patterns to autonomic stimuli, and appear to have important implications for the design of future studies of human gastrointestinal autonomic physiology and for the investigation of patients with stress related gut dysfunction.

Acoustic Stimulation↗
PubMed1987

Responses of the upper esophageal sphincter and esophageal body to graded intraluminal distension.

1. The responses of the upper esophageal sphincter (UES) to graded intraluminal distension of the esophagus were examined to determine response thresholds and to define the functional relationship between the sphincter and the esophageal body. 2. Nine normal subjects underwent manometric examination using a multiluminal tube with an attached inflatable balloon located 10 cm below the UES. Sphincter and esophageal motor responses to six balloon inflation volumes (1, 2, 4, 6, 8, and 10 ml) were recorded in each subject. 3. The UES responded to distension by increasing pressure, from a median value of 42.5 mmHg with a threshold distension of 1.0 cm, to 95 mmHg at 2.2 cm. Non-swallow-related, secondary contractile waves were stimulated in the esophageal body proximal to the distension and increased in number as inflation increased. Distal propagation of this secondary activity was inhibited with increasing distension. The amplitude of the primary peristalsis increased significantly to 61.7 mmHg at 2.2 cm. 4. These data demonstrate the normal upper esophageal motor responses to distension and provide a reference for future investigations of patients showing evidence of impaired esophageal clearance and in whom standard manometry may be unhelpful.

Adult↗
PubMed1986

Influence of the oropharyngeal microflora on the measurement of exhaled breath hydrogen.

We investigated the possible contribution made by oropharyngeal microfloral fermentation of ingested carbohydrate to the generation of the early, transient exhaled breath hydrogen rise seen after carbohydrate ingestion. Ten subjects ate or were sham fed carbohydrate-containing meals with and without prior chlorhexidine mouthwash during serial collection of exhaled breath and mouth hydrogen samples. Meal ingestion and sham feeding both induced significant (p less than 0.01) elevations of breath and mouth hydrogen that were virtually abolished by prior chlorhexidine mouthwash. In 7 subjects, delivery of the meal directly into the stomach via an orogastric tube did not cause a breath or mouth hydrogen rise. Oral contents incubated anaerobically in vitro with carbohydrate generated hydrogen that was again inhibited by chlorhexidine. These studies indicate that fermentation of ingested carbohydrate by oropharyngeal bacteria can contribute significantly to measured breath hydrogen values soon after meal ingestion, and may introduce avoidable error into the interpretation of serial breath hydrogen data.

Adult↗
PubMed1986

Aiding the development of communication skills in medical students.

Difficulties with doctor-patient communication continue to be recognized as a major barrier to effective patient care. A fundamental requirement for effective communication has been identified to be an understanding of the patient as an individual, yet most medical students are educationally and socially isolated from their patients and have difficulty in understanding their problems. In an attempt to encourage an understanding of the communication difficulties which follow such ignorance, a simple project was designed for, and conducted by, two groups of medical students during their initial period of clinical contact. Students first estimated the expected level of basic biological knowledge and the likely life-styles of their patients and then compared their estimates with data collected from patients. Students' initial estimates of both knowledge and life-style were poor, but improved significantly after data collection and discussion of results. In addition to improving their knowledge, students also recognized the benefit that such understanding could bring to the quality of communication. From these results, it is suggested that similar class exercises could be valuably introduced with minimum effort into the undergraduate curriculum, as the first of a series of steps in the acquisition of effective communication skills.

Anatomy↗
PubMed1986

Functional dyspepsia. Symptoms and underlying mechanism.

We define the concept of functional dyspepsia and analyze the putative mechanisms involved in its pathogenesis. We consider the evidence for gastroduodenitis, including the relationship of spiral organisms and viruses in this entity, and for functional dyspepsia as a manifestation of gastric secretory dysfunction and upper gut dysmotility. Functional dyspepsia is probably a heterogeneous condition in which multiple etiopathogenetic mechanisms are involved. Nevertheless, patients with functional dyspepsia constitute a sizable fraction of gastroenterological practice and therefore this disorder deserves intense research.

Bacterial Infections↗
PubMed1985

Extra intestinal influences on exhaled breath hydrogen measurements during the investigation of gastrointestinal disease.

During the clinical investigation of patients with gastrointestinal disease by exhaled breath hydrogen measurement, the occurrence of inexplicable variations in recorded hydrogen values led to a search for extra intestinal factors which were capable of adversely influencing breath hydrogen concentration and impairing the diagnostic accuracy of the test. Serial breath samples were collected from normal subjects under a variety of conditions which might occur during routine clinical study, including, hyperventilation, exercise, cigarette smoking, and carbohydrate ingestion. Breath hydrogen concentrations were consistently reduced by hyperventilation (p less than 0.01) and exercise (p less than 0.05). Cigarette smoking, in contrast, caused a marked rise in measured breath hydrogen (p less than 0.01), as did oral carbohydrate (p less than 0.05). Prior bactericidal mouthwash abolished this carbohydrate associated rise, suggesting that the hydrogen was the result of fermentation by oropharyngeal bacteria. Because, in all instances, the changes in breath hydrogen were of sufficient magnitude to interfere with data interpretation, it is recommended that these factors are eliminated, whenever possible, from conditions of study.

Bacteria, Anaerobic↗
PubMed1983

Perturbation of upper gastrointestinal function by cold stress.

To study the effects of stressful stimulus (cold pain) upon postprandial gastric, duodenal, and pancreatic function, nine healthy adult volunteers were intubated and then given two identical liquid meals, (199 cal (789 KJ) 240 ml), each being ingested during a period of irregular fasting gastroduodenal motility. Ten minutes after each meal the subjects received, in randomised order, either a test or control stimulus. The test stimulus consisted of repeated one minute immersions of a hand into ice water, with 15 seconds recovery between immersions, for a total of 20 minutes, while for the control, water at 37 degrees C was used. Serial samples of gastric and duodenal contents allowed estimation of changes in gastric emptying and acid secretion, together with pancreatic trypsin output, by a double marker perfusion technique. Measurements of blood pressure, pulse, and finger temperature acted as extra-intestinal indices of autonomic response to the stimuli. Cold pain significantly delayed gastric emptying and produced a biphasic alteration in both gastric secretion and pancreatic trypsin output, with an initial reduction during the response to the stress followed by an increase during the post-stress period. Our findings show that the normal postprandial function of the upper gut can be measurably disturbed by a stressful stimulus. The coincidence of these disturbances with other extra-intestinal autonomic changes suggests that they are a further manifestation of the somatic response to a stress.

Adult↗
PubMed1982

Sustained mental stress alters human jejunal motor activity.

The effect of prolonged mental stress on upper small bowel motility was studied in 11 healthy, medical students using a pressure-sensitive radio-pill. During eight hours of continuous observation, subjects were stressed for four hours with a modified dichotomous listening test. During the first two hours of stress, inhibition of fasting motor complexes occurred and this effect was marked in the seven subjects who showed an appreciable cardiovascular response to stress.

Adult↗
PubMed1982

Patterns of small intestinal motility in duodenal ulcer patients before and after vagotomy.

Prolonged (18-24 hours) recordings of the pattern of small intestinal motor activity have been made, using radiotelemetry, in seven patients before surgery for chronic duodenal ulcer, seven after truncal vagotomy, and four with persistent post-vagotomy diarrhoea. There was no difference in the pattern of fasting cyclical activity between the three groups but the duration of feeding activity after a standard meal was reduced in asymptomatic truncal vagotomy patients compared with duodenal ulcer controls (p less than 0 . 05). In patients with post-vagotomy diarrhoea, the duration of the feeding pattern was further reduced compared with the asymptomatic post-vagotomy patients (p less than 0 . 001). It is suggested that altered emptying of food from the stomach in these patients together with duodenal receptor insensitivity is the probable explanation of these changes.

Adult↗
PubMed1982

Gastric emptying as a determinant of the oral glucose tolerance test.

Intraindividual variation in the results of repeated oral glucose tolerance tests in normal subjects is well recognized but incompletely explained. The present studies show that such variation can be produced by ingestion of the glucose solution during different phases of the normal fasting activity cycle of the upper gut. Such variation is not seen when glucose is administered intraduodenally during the same phases of activity. Gastric emptying shows similar variation with the activity cycle; larger volumes of solution were emptied from the stomach during activity than quiescence, thus presenting greater quantities of glucose solution to the small intestine for absorption. Metoclopramide and hyoscine butylbromide, drugs known to influence the rate of gastric emptying, reduced the variation in the glucose tolerance test. The data suggest na possible use of the glucose tolerance test for the assessment of gastric emptying.

Activity Cycles↗
PubMed1982

Perturbation of gastric emptying and duodenal motility through the central nervous system.

This study was undertaken to test the hypothesis that external stimuli acting through the central nervous system perturb the normal gastrointestinal response to meals. Thus, in 4 healthy volunteers we used a multilumen gastroduodenal tube system that allowed simultaneous measurements of gastroduodenal motility, gastric emptying rate, gastric acid secretion, and pancreatic trypsin output. Blood pressure, pulse rate, and skin temperature were also monitored for autonomic response. All subjects were studied on 2 days, receiving on each day two identical test meals. After one of the meals on each day, vertigo was induced by labyrinthine stimulation (ear irrigation with ice water) while the other meal was followed by one of two controls, ear irrigation at 37 degrees C (control stimulation) on 1 day and no stimulation on the other, the order of the tests being randomized. Labyrinthine stimulation at subnauseant levels resulted in a consistent and reproducible delay in gastric emptying of the meal. Further, in 2 of the 4 subjects a marked and reproducible alteration of the postprandial duodenal motility pattern occurred, with a change to one resembling the fasted state, even though nutrients continued to be present in the stomach. Duodenogastric reflux and gastric acid output remained unchanged. Trypsin output decreased initially but later returned to control values. These studies emphasize the role of the central nervous system in the control of gut function after feeding. Labyrinthine stimulation nay be a useful method for investigating inhibitory and disruptive effects of centrally acting stimuli on the human upper gut.

Adolescent↗
PubMed1981

Guts and their motions (gastrointestinal motility in health and disease).

In the last decade, a much greater understanding of human upper intestinal motility has been obtained. The existence of a cyclical fasting pattern is now recognized, associated with intermittent secretion and propulsion of material through the stomach and small intestine. This pattern changes after the ingestion of food, the duration of the disruption depending upon both quality and quantity of nutrient ingested. The present clinical relevance of this phenomenon is twofold. 1) In normal fasting persons, the passage and absorption by the small intestine of food and drugs may be influenced by such periodic changes. 2) Motility abnormalities in disease states may account for associated gastrointestinal symptoms. While the number of disorders showing clinically relevant motor dysfunction is small, continuing study will undoubtedly bring others to light, and may even provide a rational basis for therapy.

Bacterial Infections↗
PubMed1981

Oral hyoscine butylbromide does not alter the pattern of small intestinal motor activity.

1. Continuous recording of proximal jejunal motility of conscious healthy subjects was made following ingestion of 200 mg hyoscine butylbromide (ten times the recommended therapeutic dosage). 2. There was no detectable modification of fasting or postprandial motor activity, although the therapeutic potency of the standard intravenous dose was confirmed.

Administration, Oral↗
PubMed1981

Fasting motor activity occurs during a day of normal meals in healthy subjects.

Using a radiotelemetric technique of pressure recording which did not interfere with normal feeding, jejunal motor activity was recorded in seven healthy human subjects, who were given three hospital meals during the course of a day, and allowed ad libitum supplementary snacks. Fasting motor activity was detected during the day in five subjects, and, although its occurrence was very variable, tended to occur shortly before the next meal.

Adult↗