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Biomedical subjects

N W Read

Publications and source records attributed to N W Read.

At least 109 records · Page 6Linked to original sources
PubMed1992

Effect of hysterectomy on anorectal and urethrovesical physiology.

To investigate whether vaginal or total abdominal hysterectomy is associated with changes in anorectal and urethrovesical physiology, 26 women were studied before operation and six weeks and six months afterwards. The results showed a postoperative increase in both rectal and vesical sensitivity (p less than 0.01). Similar results were observed irrespective of the type of hysterectomy. No significant changes in rectal or bladder compliance were noted, and anal pressure and urethral pressure and length were unchanged after surgery. Whole gut transit was not affected by hysterectomy. Urinary symptoms occurred de novo in 6/26 women and gastrointestinal symptoms in 2/26 women. These results show that significant changes in rectal and vesical sensitivity occur after hysterectomy for benign disease. These persist for at least six months postoperatively but are not always associated with development of urinary or gastrointestinal symptoms.

Adult↗
PubMed1992

Utility of a combined test of anorectal manometry, electromyography, and sensation in determining the mechanism of 'idiopathic' faecal incontinence.

Combined tests of anorectal manometry, sphincter electromyography and rectal sensation were carried out in 302 patients with faecal incontinence (235 women, 67 men). The results obtained were compared with 65 normal subjects (35 women, 30 men). A mechanism for incontinence was identified in all and the majority of patients had more than one abnormality. Two hundred and seventy eight patients (92%) had a weak external anal sphincter, 185 of these (67%, mostly women) also showed abnormal perineal descent, and 14 women showed clinical evidence of sphincter damage as a result of obstetric trauma. Ten per cent of patients with impaired external anal sphincter contraction showed associated evidence of spinal disease (impaired rectal sensation plus attenuated or enhanced reflex external anal sphincter activity). Unlike the other groups, the 'spinal' group contained equal numbers of men and women. Ninety seven patients (32%) had evidence of a weak internal anal sphincter. The external sphincter was also very weak and 92% of these patients also had perineal descent. Eighty two patients (27%) showed an unstable internal sphincter, characterised by prolonged 'spontaneous' anal relaxation under resting conditions and an abnormal reduction in anal pressure after conscious contraction of the sphincter or an increase in intraabdominal pressure. One hundred and forty two patients (47%) had a hypersensitive rectum associated with enhanced anorectal responses to rectal distension. All these patients had an abnormally weak external sphincter, suggesting that the hypersensitive or 'irritable' rectum should not be regarded as a cause of faecal incontinence unless accompanied by external sphincter weakness. Twenty four patients (8%) showed a normal basal and squeeze pressures and impaired rectal sensation; six showed giant rectal contractions during rectal distension. The results show that idiopathic faecal incontinence is not caused by a single abnormality, and it is suggested that combined anorectal manometry, electromyography, and sensory testing is a useful technique to identify the causes of faecal incontinence and provide a basis for appropriate treatment.

Adolescent↗
PubMed1992

Relation between hysterectomy and the irritable bowel: a prospective study.

Some women with irritable bowel syndrome date the onset of symptoms to previous hysterectomy. To assess prospectively the incidence of gastrointestinal symptomatology arising de novo after hysterectomy, and to study the effect of surgery on pre-existing symptoms, 205 women completed a symptom questionnaire before and six weeks and six months after surgery. Beforehand, symptoms suggestive of irritable bowel syndrome occurred in 22% of patients. At six months after operation, 60% of these had improved or were symptom free while 20% had increased symptomatology. New gastrointestinal symptoms were present more than once per week in 10% of previously asymptomatic women. Constipation predominant irritable bowel syndrome was the commonest symptom complex seen de novo, occurring more than once per week in 5% of the group. No relation was found between new symptomatology and the type of hysterectomy, oophorectomy, or the administration of perioperative antibiotics. This study suggests that many women with pre-existing gastrointestinal symptomatology improve after hysterectomy. However, symptoms suggestive of irritable bowel syndrome do arise de novo in 10%. As hysterectomy is common, gastroenterologists can expect to see women presenting with post-hysterectomy problems.

Adult↗
PubMed1992

Effect of short-chain fatty acids on contractile activity and fluid flow in rat colon in vitro.

The effect of short-chain fatty acids (SCFAs) on the contractile activity and fluid output of the large bowel of the rat was studied using an isolated segment of cecum and colon, mounted in vitro. The rate of contractile activity per minute in the proximal, mid, and distal regions of the colon was depressed by luminal infusion of associated SCFAs either as a mixture (acetic, propionic, and butyric) or individually (100 mM/pH = 4.1, in each case). Dose responses were observed for the individual fatty acids, with the 100 mM solutions eliciting a more prominent reduction in colonic motor activity than that induced by 10 mM. Neither the Na salt of the fatty acids nor an acidified Krebs solution (pH = 4.1) inhibited contractile activity or fluid output. No reduction in the rate of contractile activity was observed in the cecum with any test solutions, except 100 mM butyric acid. The data suggest that SCFAs inhibit smooth muscle contractility and resultant fluid transit.

Animals↗
PubMed1992

Further evaluation of the afferent nervous pathways from the rectum.

To evaluate the visceral afferents from the rectum, we recorded cerebral evoked potentials (EPs) in 26 healthy subjects after electrical stimulation of the rectum, pudendal nerve, and posterior tibialis nerve. We found two distinctly different EPs after rectal stimulation, with differences in latencies and pattern. In 13 subjects (group 1), the EP after rectal stimulation had multiple prominent peaks with early onset latencies ranging from 22 to 29 ms (mean 26 ms). In 13 subjects (group 2), the EP after rectal stimulation had a trifid configuration due to a very prominent negative peak between 97 and 108 ms (mean 101 ms) and longer onset latencies ranging from 50 to 61 ms (mean 55 ms). Latencies after pudendal nerve and posterior tibialis nerve stimulation were similar in the two groups. On further study, we found that both types of afferent pathways are present in the distal colon, since both types of EPs were found in the same subjects either in the rectum or in the rectum and sigmoid. We speculate that the early onset EP is a visceral pathway using the same afferents as the pudendal nerve because the early onset EP after rectal stimulation appears similar in number of peaks and interpeak latencies to EPs recorded after pudendal nerve stimulation, and the late onset EP is a visceral pathway using afferents along the pelvic nerve. Early onset EPs were also recorded after sigmoid stimulation, suggesting that both kinds of EPs are visceral afferents.

Adult↗
PubMed1991

Applied potential tomography. Noninvasive method for measuring gastric emptying of a solid test meal.

Applied potential tomography (APT) is a new noninvasive, nonradioactive method of measuring gastric emptying, which generates profiles of emptying of liquids that are similar to those obtained simultaneously by scintigraphy and dye dilution. This study validates the ability of APT to measure emptying of a solid beefburger test meal from the stomach by comparing the results obtained with those obtained simultaneously by scintigraphy. When acid secretion was inhibited, there was a significant correlation between the two methods for the time taken for half the meal to empty from the stomach and the amount of meal emptied at different time intervals. Furthermore, the profiles of gastric emptying obtained by APT resembled those obtained by scintigraphy in most studies. If acid secretion was not inhibited, there was no correlation between values obtained by the two methods.

Adult↗
PubMed1991

Is rectosigmoid response to food modulated by proximal colon stimulation?

Rectosigmoid motor activity and postprandial breath hydrogen levels were monitored in eight healthy males under basal conditions and for 3 1/2 hr after a meal (beefburger and breadroll and ice cream incorporating 20 g lactulose). Within minutes of ingestion there was a significant increase in motility index (P less than 0.05) and also an initial temporary rise in breath hydrogen. A late increase in motor activity occurred in seven of eight subjects 123 +/- 19 min after the meal and was temporally related to the beginning of a second, much larger rise in breath hydrogen (r = 0.99; P less than 0.01). The close association between the timing of the rises in breath hydrogen and rectosigmoid motor activity would support the possibility that the latter may be generated by chemical or mechanical stimulation of the proximal colon.

Adult↗
PubMed1991

Disturbed gastroduodenal motility in patients with active and healed duodenal ulceration.

Disordered gastroduodenal motility may promote duodenal ulceration by allowing prolonged acid contact with the duodenal mucosa. Using a multilumen perfused catheter incorporating 3 pH microelectrodes, antral and duodenal pH and antropyloroduodenal pressure activity were recorded in 36 subjects (10 with healed duodenal ulceration, 11 with active duodenal ulceration, and 15 healthy volunteers) during fasting and after a radiolabeled solid test meal. Correct pH probe/catheter position was continuously verified by recording transmucosal potential difference across the pylorus. Patients with active and healed duodenal ulcer had similarly disordered gastroduodenal motility. The chief abnormalities consisted of an increase in postprandial duodenal retroperistalsis (healed duodenal ulceration, 12 +/- 1 events per hour; active duodenal ulceration, 12 +/- 1; control, 6 +/- 1; mean +/- SEM: healed and active duodenal ulceration vs. control, P = 0.004 and P = 0.03, respectively), a reduction in pressure waves sweeping aborally through the duodenum after the meal (healed duodenal ulceration, 22 +/- 4 events per hour; active duodenal ulceration, 23 +/- 3; control, 34 +/- 4: healed and active duodenal ulceration vs. control, P = 0.04 and P less than 0.05, respectively), and an increased incidence of atypical, complex forms of coordinated duodenal motor activity throughout the study (postprandial data; healed duodenal ulceration, 8 +/- 1 events per hour; active duodenal ulceration, 10 +/- 1; control, 4 +/- 1: healed and active duodenal ulceration vs. control, P = 0.02 and P less than 0.02, respectively). In addition, gastric emptying of the solid test meal was significantly delayed in healed, but not active, duodenal ulceration [half-emptying time, healed duodenal ulceration 185 minutes (117-235); active duodenal ulceration 102 minutes (80-200); control 107 minutes (78-130): healed duodenal ulceration vs. control, P less than 0.009]. Duodenal bulb pH was similar in controls and patients with active duodenal ulceration; however, bulb pH was less than 4 for a significantly greater period of time in healed duodenal ulceration compared with active ulcer patients, particularly after the meal. In conclusion, duodenal ulcer disease is associated with disturbed gastroduodenal motility, even when the ulcer is quiescent and when intraduodenal acidity is low. In healed duodenal ulceration, disturbed motility may promote ulcer relapse by impairing acid clearance from the bulb. However, in active ulceration other factors such as mucosal bicarbonate secretion may have a more influential role in determining intraduodenal pH.

Adult↗
PubMed1991

The effect of short-term dietary supplementation with glucose on gastric emptying in humans.

In order to test whether gastric motility can adapt to changes in nutrient load, gastric emptying of hyperosmotic glucose and protein drinks was measured by applied potential tomography in two groups of ten volunteers following dietary supplementation with 400 g glucose/d for 3 d. The half emptying time for the glucose test meal was significantly faster after the standard diet had been supplemented with glucose compared with the standard diet alone (median and range, 20.7 (4.6-36.8) v. 29.1 (19.8-38.4) min; P less than 0.05), while the emptying of the protein drink (Oxo; Brooke Bond Ltd) was unchanged (median and range, 18.0 (12.5-23.6) v. 16.1 (9.6-22.7) min). These results suggest that rapid and specific adaptation of the small intestinal regulatory mechanisms for gastric emptying of nutrient solutions can occur in response to increases in dietary load. This adaptation may be explained by desensitization of nutrient receptors or by a reduction in the area of receptor field exposed to nutrients caused by increased absorption of glucose in the upper small intestine.

Adult↗
PubMed1991

The effect of a 5-HT3-antagonist on the ileal brake mechanism in the rat.

Studies have been carried out on 7 male adult rats to investigate how the action of the selective 5-HT3 receptor antagonist, granisetron, influences gastrointestinal transit under control conditions and when it is delayed by ileal infusion of lipid. Stomach to caecum transit time (SCTT) was measured using environmental hydrogen analysis. Subcutaneous administration of granisetron (BRL 43694, 40 micrograms kg-1) significantly delayed the passage of the head of the baked bean meal through the stomach and the small intestine under control conditions (P less than 0.05). The same compound, however, significantly reversed the delay in SCTT induced by ileal infusion of lipid (P less than 0.001). These apparently paradoxical results may be rationalized by postulating inhibition of receptors on afferent nerves initiating reflexes that both accelerate and delay transit.

Animals↗
PubMed1991

Influence of acid-pepsin secretion on gastric emptying of solids in humans: studies with cimetidine.

The commonly accepted model for gastric emptying suggests that the 'antral mill' is responsible for the triturition and subsequent emptying of solid food from the stomach. Little is known about the contribution to solid emptying made by other digestive mechanisms such as acid-pepsin secretion. We have investigated the effect of inhibiting gastic secretion on the rate at which a solid test meal emptied from the stomach. Using a radiolabelled beefburger, we performed paired gammacamera studies on consecutive days in 10 fasted, healthy volunteers to compare gastric emptying of the test meal with and without oral cimetidine (400 mg 1 hour before the test, 800 mg at the start of the meal). Inhibition of acid-pepsin secretion by cimetidine was associated with an appreciable delay in the rate of emptying of the burger from the stomach (T50 cimetidine 187 (16) min (mean (SEM); T50 no cimetidine 146 (15) min; p less than 0.01, paired t test). This delay was related to a change in the slope of the emptying profile and was not associated with a prolonged lag phase. These results may be explained by the relative achlorhydria and reduced pepsin activity induced by cimetidine impairing the breakdown of solid food into particles small enough to leave the stomach.

Adolescent↗
PubMed1991

Intermittent rectal motor activity: a rectal motor complex?

Prolonged nocturnal recordings from multiple sites in the anorectum and duodenum were performed in 12 healthy volunteers to investigate the presence and determine the characteristics of nocturnal rectal motor activity and assess any synchronicity with phase III of the small intestinal migrating motor complex. Runs of phasic contractions of two contractile frequencies (3 or 6/minute), sustained for more than three minutes, and preceded and followed by motor quiescence were observed in 10 of the 12 subjects. This phenomenon is similar to that described by other investigators and termed the 'rectal motor complex'. The runs of contractions showed considerable inter- and intrasubject variation, with a duration of 3-30 minutes (median 9.0), amplitude of 10-55 mm Hg (median 20.0), and periods of 10-420 minutes (median 55.5) between contractile activity. There was no propagation through the rectum, the phasic motor activity rarely occurred simultaneously at more than one rectal recording site. No consistent relation with phase III of the small intestinal migrating motor complex was observed in any subject. In view of these findings, we question whether this intermittent motor activity merits the term 'rectal motor complex'.

Adult↗
PubMed1991

Short chain fatty acids in the terminal ileum accelerate stomach to caecum transit time in the rat.

We have previously shown that infusion of triglycerides and long chain fatty acids into the ileum of humans and rats delays small bowel transit time. The present studies have investigated the effect on the stomach to caecum transit time of a baked bean meal of the ileal infusion of 20 mM, 50 mM, and 100 mM acetic, butyric, hexenoic, and caprylic acids in rats. After an 18 hour fast either a control or a short chain fatty acid (SCFA) solution (pH 6.5) was infused into the ileum for 30 minutes (0.3 ml/hour). A test meal was given by gavage and the infusion continued for a further 150 minutes. The arrival of the meal in the colon was signalled by a rise in the exhaled hydrogen concentration. Acetic acid (20 mM, 50 mM, 100 mM), butyric acid (100 mM), and caprylic acid (100 mM) produced a significant acceleration of transit which was inversely proportional to SCFA chain length. In a separate experiment, infusion of 100 mM acetic acid, the most potent SCFA, into an isolated ileal Thirty-Vella loop failed to accelerate transit of the test meal. Our results suggest that SCFAs accelerate transit via a local enteric reflex.

Acetates↗
PubMed1991

Gastrointestinal adaptation to diets of differing fat composition in human volunteers.

The effect of a low fat diet (9 MJ) v a high fat diet (19.26 MJ), each consumed separately for four and 14 days, on gastric emptying and mouth to caecum transit time of a high fat test meal and body weight and satiety were examined in groups of 10 and six normal male volunteers. The half time for gastric emptying (t1/2) and the mouth to caecum transit time of a high fat test meal was significantly faster after the high fat diet than the low fat diet when consumed for 14 days (t1/2=98 (80-116) v 147 (88-206) minutes (median (range)), p less than 0.05; mouth to caecum transit time 240 (130-350) v 360 (200-520) minutes, p less than 0.05), but not when consumed for only four days. The mean (SEM) body weight of all subjects significantly increased during the 14 day high fat diet (74.7 (1.3) v 72.7 (1.6) kg, p less than 0.05) but was not influenced during the consumption of the low fat diet. When subjects were given an appetising meal to consume on the day that they had consumed the transit test meal, they ate similar amounts irrespective of their recent dietary history, though the eating rate was significantly slower after the high fat diet (mean (SEM)) 46.7 (1.9) v 71.3 (14.8)/min, p less than 0.05). Maintaining normal subjects on a high or low fat diet for two weeks resulted in a desensitisation or sensitisation respectively of the mechanisms by which nutrients regulate gastrointestinal transit. These findings emphasise the importance of the recent dietary history in the interpretation of gastric emptying and small bowel transit time data.

Adaptation, Physiological↗
PubMed1991

Role of the proximal and distal stomach in mixed solid and liquid meal emptying.

The role of the proximal and distal stomach in the emptying of solids and liquids from the stomach remains unclear. We have used a dual isotope technique to quantify proximal and distal stomach emptying of a solid (100 g of 99mTc labelled liver/ground beef) liquid (either 200 ml of normal saline (eight subjects) or 25% dextrose (seven subjects) labelled with 113mIn-diethylenetriaminepenta-acetic acid) mixed meal. A manometric catheter simultaneously measured antral, pyloric, and duodenal motor activity. The liquid component dispersed rapidly throughout the stomach and emptied after a minimal lag period. The emptying of the 25% dextrose was delayed compared with the saline. This delay was associated with increased retention of the liquid in the distal stomach, a significant increase in localised phasic pyloric contractions, and a suppression of antral contractions. The solid component initially resided wholly within a proximal stomach reservoir area. Solids then redistributed from proximal to distal stomach during the emptying of liquid from the stomach. Dextrose delayed gastric emptying of solids compared with saline by increasing the solid lag period and retention in the proximal stomach. There was no significant difference between saline and dextrose meals in the distal stomach retention of solid or in the linear rate of emptying after the lag period. We conclude that, contrary to general opinion, the proximal stomach plays an important role in the control of gastric emptying of solids while the distal stomach is important in the emptying of nutrient liquids.

Adolescent↗