Functional gastroenterological disorders: the name's the thing ...
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Chronic Disease↗
Biomedical subjects
N W Read
Publications and source records attributed to N W Read.
Effect of cisapride on the gastrointestinal transit of a solid meal in normal human subjects.
The effect of cisapride, a new gastrointestinal prokinetic agent, on the transit of a standard meal through the stomach, small intestine and colon was studied in 10 normal subjects. Cisapride had no significant effect on gastric emptying but decreased mouth to caecum transit time (p less than 0.01). Stool weight and frequency were not significantly increased but the time for the first appearance of stool markers and the arrival of 20% and 50% of stool markers was decreased after cisapride (p less than 0.05).
Adult↗
Preservation of faecal continence during rises in intra-abdominal pressure: is there a role for the flap valve?
Studies were carried out in 15 normal subjects and 14 patients with idiopathic faecal incontinence to test whether a rectoanal flap valve could be responsible for maintaining faecal continence in man. Intraluminal pressures were recorded from the rectum and from three sites in the anal canal during serial increases in intra-abdominal pressure, produced by forced expiration into a sphygmomanometer keeping the height of the column of mercury at prescribed levels. The anal pressures in the normal volunteers always remained higher than the intrarectal pressures even when these were as high as 230 cm H2O. This pressure gradient was the reverse of that which would be found if an anterior rectal flap valve maintained continence and suggests instead that continence is normally maintained by a reflex contraction of the external anal sphincter. The anal pressures in patients with idiopathic faecal incontinence, however, fell below the rectal pressure as the intra-abdominal pressure increased, creating the conditions for a flap valve. The valve was incompetent, however, because fluid infused into the rectum leaked from the anus whenever the rectal pressure exceeded the anal pressure.
Adult↗
Effect of stool size and consistency on defecation.
The ability of subjects to expel from the rectum objects simulating stools of different characteristics was assessed in paired studies carried out in a total of 58 normal subjects and 25 young women with severe constipation. Our results showed that a lower percentage of normal subjects and a lower percentage of constipated patients were able to pass a 1.8 cm incompressible sphere compared with a 50 ml deformable balloon, although constipated patients found it more difficult than normal subjects to expel both types of simulated stool. It was also more difficult for normal subjects to pass a soft compressible silicon rubber simulated stool than a stool made up of a similar volume of incompressible 1 cm wooden spheres contained in a cylindrical latex envelope, but both objects were much easier to pass than the same number of 1 cm spheres placed loose within the rectum. When normal subjects were instructed to expel single incompressible spheres of different sizes placed in the rectal ampulla, the intrarectal pressure and the time needed to pass these objects varied inversely with their diameter. These results suggest that more effort is required to expel stools from the rectum if they are small and hard than if they are large and soft.
Adult↗
Influence of olsalazine on gastrointestinal transit in ulcerative colitis.
The effect of olsalazine on stool output and the transit of a solid radiolabelled meal through the stomach, small intestine and colon was studied in six patients with ulcerative colitis intolerant of sulphasalazine. Olsalazine 250 mg four times daily significantly accelerated gastric emptying (mean +/- SD; 45.3 +/- 24.2 min v 67.3 +/- 33.1 min, p less than 0.05), mouth to caecum transit time (242 +/- 41 min v 325 +/- 33 min, p less than 0.02) and whole gut transit time (60.5 +/- 26 h v 37.8 +/- 17.8 h, p less than 0.05). No significant changes were seen in mean daily stool weight (215 +/- 41 g v 162 +/- 62 g) and mean daily stool frequency (2.2 +/- 0.6 v 2.4 +/- 1.8). None of these patients developed diarrhoea, but acceleration of gastric and intestinal transit may be responsible for the diarrhoea reported in some patients taking this drug.
Adult↗
Effect of food consistency on gastric emptying in man.
The gastric emptying of two radiolabelled pancake meals of identical composition, but different consistency, was compared with the rates at which they could be broken down in vitro by mechanical agitation in a solution of either acid-pepsin or saline. Neither of the pancake meals were broken up within 150 minutes by mechanical agitation in a normal saline medium, but both were disrupted in the presence of acid-pepsin, the light consistency pancake being broken up more rapidly than the heavy consistency pancake (0.5 +/- 0.1 v 0.2 +/- 0.1% radioactivity appearing in the bathing medium per minute, p less than 0.01). Under normal conditions, the pattern and rate of gastric emptying of both meals was similar. Stimulating acid secretion with pentagastrin (6 micrograms/kg bodyweight sc) delayed the onset of emptying of both pancakes and tended to increase the slope of emptying. Under these conditions, the denser pancake was emptied more slowly than the lighter pancake because of an increase in the lag period. Thus the data did not confirm the hypothesis that the rate of emptying of disruptible solid food from the stomach under normal conditions of acid secretion is influenced by the ease with which it can be broken down by mechanical agitation in an acid-pepsin medium. The trend for an accelerated rate of emptying after administration of pentagastrin, however, may well be explained by the increased rate of disruption of the food in the presence of acid, but the longer lag periods are more compatible with inhibition of gastric emptying caused by free acid in the duodenum.
Adolescent↗
Effect of aging on anorectal function.
Measurements of anorectal function were conducted on 37 elderly (66-87 years) and 48 young (19-55 years) normal subjects. Elderly subjects had decreased anal pressures compared with younger subjects, required lower rectal volumes to inhibit anal sphincter tone and had increased rectal pressures upon balloon distension. The rectal volume required to cause the desire to defecate and the maximum tolerated volume were lower in the elderly, but the corresponding rectal pressures were similar, indicating the sensations were mediated by tension, or pressure receptors. Rectal contractions were generated at similar degrees of rectal distension. A lower proportion of elderly, compared with young subjects could defecate a sphere 18 mm in diameter within 20 seconds. The degree of perineal descent was greater in the elderly female subjects compared with the young women, although there was no difference in this measurement between men. The anorectal angle was similar in young and old. The changes in anorectal function in the elderly would tend to make them more susceptible to faecal incontinence.
Adult↗
Adaptation of hydrogen analysis to measure stomach to caecum transit time in the rat.
Excreted hydrogen analysis was used to measure stomach to caecum transit time of the head of a test meal in 120 rats fed by gavage. Results were compared with the distribution of a labelled test meal in the gastrointestinal tract of rats killed at different time intervals after gavage. Values for stomach to caecum transit were compatible with the distribution of labelled meals in 91% of animals, although in the remainder the hydrogen concentration had not risen even though food residues were in the caecum when the animals were killed. The technique gave reproducible results; the coefficients of variation for four studies carried out in each of six animals varied between 4 and 14%. A meal consisting of homogenised baked beans had a significantly shorter stomach to caecum transit time (88.1 +/- 4.5 min; mean +/- SE; n = 21; p less than 0.001) than an equivalent volume of Complan/lactulose (180.9 +/- 8.7 min; n = 13). This technique was used to investigate the effect of ileal infusion of a fat emulsion (20% Intralipid) via a chronically implanted intestinal cannula on the stomach to caecum transit time of a bean meal, in a series of paired studies carried out in six rats. Stomach to caecum transit time was significantly delayed during ileal infusion of 20% Intralipid compared with the control infusion of an isotonic saline solution (218.3 +/- 21 min v 106.7 +/- 33 min Intralipid v saline; n = 6; p less than 0.001).
Animals↗
Is the diarrhoea in ulcerative colitis related to impaired colonic salvage of carbohydrate?
In order to determine whether failure of the colon to salvage carbohydrate could contribute to the diarrhoea of ulcerative colitis we investigated the effect of ingesting a drink containing 20 g lactulose on stool output and breath hydrogen production in 39 colitic patients subdivided according to their disease extent and activity and in 14 normal volunteers. Each subject took a standard diet for four days and stool output was monitored throughout this period. Administration of lactulose on day three significantly increased stool weight and frequency in patients with both active and quiescent total colitis (p less than 0.01), but not in patients with distal colitis or in the volunteers. The basal and peak breath hydrogen responses to ingested lactulose were similar to normal controls in all patient groups but the hydrogen concentration tended to be higher in colitics. The mouth to caecum transit of the lactulose meal was slower in all groups of colitics (p less than 0.02) when compared with controls. These results suggest that impaired colonic salvage of carbohydrate could contribute to the diarrhoea in patients with total colitis who are ingesting a diet rich in unabsorbed carbohydrate, or who are hypolactasic.
Adult↗
Irritable bowel syndrome (IBS)--definition and pathophysiology.
The article presents some individual perceptions of the nature of the disease we call the Irritable Bowel Syndrome (IBS), and attempts to rationalise the variable presenting features, the influence of the psyche and the lack of pathological or biochemical markers. Among the topics discussed include the existence of recognisable subsets of the disease, the influence of mental stress, and the pathophysiology of the presenting symptoms. My impression is that IBS is a condition, in which the gut is hypersensitive and hyper-reactive to mechanical and chemical stimuli and as such, can be compared with asthma in the respiratory system. This hyper-reactivity could be caused by increased mucosal permeability, increased numbers and/or responses of effector cells such as mast cells or enterochromaffin cells, and enhancement of intrinsic nerve reflexes by increased activity of efferent vagal fibres.
Colonic Diseases, Functional↗
Constipation: is there light at the end of the tunnel?
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Aged↗
Applied potential tomography. A new noninvasive technique for measuring gastric emptying.
Applied potential tomography is a new, noninvasive technique that yields sequential images of the resistivity of gastric contents after subjects have ingested a liquid or semisolid meal. This study validates the technique as a means of measuring gastric emptying. Experiments in vitro showed an excellent correlation between measurements of resistivity and either the square of the radius of a glass rod or the volume of water in a spherical balloon when both were placed in an oval tank containing saline. Altering the lateral position of the rod in the tank did not alter the values obtained. Images of abdominal resistivity were also directly correlated with the volume of air in a gastric balloon. Profiles of gastric emptying of liquid meals obtained using applied potential tomography were very similar to those obtained using scintigraphy or dye dilution techniques, provided that acid secretion was inhibited by cimetidine. Profiles of emptying of a mashed potato meal using applied potential tomography were also very similar to those obtained by scintigraphy. Measurements of the emptying of a liquid meal from the stomach were reproducible if acid secretion was inhibited by cimetidine. Thus, applied potential tomography is an accurate and reproducible method of measuring gastric emptying of liquids and particulate food. It is inexpensive, well tolerated, easy to use, and ideally suited for multiple studies in patients, even those who are pregnant.
Colloids↗
Role of anal cushions in maintaining continence.
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Adult↗
Irritable bowel syndrome: a paroxysmal motor disorder?
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Colonic Diseases, Functional↗
Anal hypertonia in fissures: cause or effect?
High sphincter pressures recorded in patients with fissure-in-ano have been attributed to sphincter spasm induced by wide recording assemblies. To investigate this hypothesis, anal sphincter pressure was measured using a series of perfused probes of 0.4-2 cm diameter in six men with chronic anal fissure in whom digital examination was easily tolerated. The results were compared with those from 14 normal men. The resting pressure within the anal canal exceeded the normal range in all six patients irrespective of probe size. With the smallest (0.4 cm) probe, the resting pressure was 114 +/- 17.1 cmH2O (mean +/- s.d.) in patients with fissure and 73.1 +/- 27.0 cmH2O (mean +/- s.d.) in control subjects (P less than 0.001) even 10 min after introduction of the device. The minimum residual pressure attained during inflation of a rectal balloon with 100 ml of air was higher in patients with anal fissure than controls, reaching statistical significance with the 1.0 cm probe (80.8 +/- 17.7 cmH2O versus 36.9 +/- 19.0 cmH2O, P less than 0.001). Maximum pressures recorded during a voluntary contraction of the sphincter were no higher than in control subjects. The results suggest that high resting pressures are recorded in patients with chronic anal fissures even when small probes are employed and are unlikely to be due to spasm, but probably represent a true increase in basal sphincter tone. It is proposed that elevated sphincter pressures may cause ischaemia of the anal lining and this may be responsible for the pain of anal fissures and their failure to heal.
Adult↗
Effect of lidamidine, a proposed alpha 2-adrenoreceptor agonist, on salt and water transport in human jejunum.
The effects of a new antidiarrheal agent, lidamidine (10 mg per os) and an identical placebo on jejunal fluid and electrolyte transport in vivo were investigated in five normal volunteers during steady-state perfusion of a 25-cm length of jejunum with a plasma-like solution. Studies were carried out under basal conditions and during secretion stimulated by incorporation of prostaglandin E2 (5 X 10(-6) M) in the infusate. Lidamidine had no significant effect on jejunal fluid transport under basal conditions but reduced secretion induced by prostaglandin E2 (P less than 0.05).
Adrenergic alpha-Agonists↗
An analysis of anal sphincter pressure and anal compliance in normal subjects.
To investigate anal sphincter mechanics, anal pressure was measured in 14 normal males and 11 normal females using probes of 0.4 to 3 cm in diameter. Resting pressure profiles on insertion and withdrawal did not differ significantly. Anteroposterior pressure differences could be explained by leverage of rigid probes against the anterior rectal wall. A maximal voluntary squeeze increased pressure throughout the anus, whereas the recto-anal inhibitory reflex resulted in a greater reduction in pressure in the upper part of the anal canal. Resting pressure, squeeze pressure and minimum residual pressure (during rectal distension) rose with increasing anal diameter. Estimated sphincter tension was linearly related to anal diameter and the slope of this relationship was increased by sphincter contraction and reduced by sphincter relaxation. The deviation from linearity of this relationship at low anal diameters may be due to swelling of the anal cushions to maintain anal pressure when muscular tension approaches zero.
Adult↗