W M Sun

Royal Adelaide Hospital, Adelaide, South Australia, Australia

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Publications (49)269.56 Total impact

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    Article: Effects of acute hyperglycaemia on anorectal motor and sensory function in diabetes mellitus.
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    ABSTRACT: To determine the effects of acute hyperglycaemia on anorectal motor and sensory function in patients with diabetes mellitus. In eight patients with Type 1, and 10 patients with Type 2 diabetes anorectal motility and sensation were evaluated on separate days while the blood glucose concentration was stabilized at either 5 mmol/l or 12 mmol/l using a glucose clamp technique. Eight healthy subjects were studied under euglycaemic conditions. Anorectal motor and sensory function was evaluated using a sleeve/sidehole catheter, incorporating a barostat bag. In diabetic subjects hyperglycaemia was associated with reductions in maximal (P<0.05) and plateau (P<0.05) anal squeeze pressures and the rectal pressure/volume relationship (compliance) during barostat distension (P<0.01). Hyperglycaemia had no effect on the perception of rectal distension. Apart from a reduction in rectal compliance (P<0.01) and a trend (P=0.06) for an increased number of spontaneous anal sphincter relaxations, there were no differences between the patients studied during euglycaemia when compared with healthy subjects. In patients with diabetes, acute hyperglycaemia inhibits external anal sphincter function and decreases rectal compliance, potentially increasing the risk of faecal incontinence.
    Diabetic Medicine 02/2004; 21(2):176-82. · 2.90 Impact Factor
  • Article: Relationship between ultrasonically detected phasic antral contractions and antral pressure.
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    ABSTRACT: The relationships between gastric wall motion and intraluminal pressure are believed to be major determinants of flows within and from the stomach. Gastric antral wall motion and intraluminal pressures were monitored in five healthy subjects by concurrent antropyloroduodenal manometry and transabdominal ultrasound for 60 min after subjects drank 500 ml of clear soup. We found that 99% of antral contractions detected by ultrasound were propagated aborally, and 68% of contractions became lumen occlusive at the site of the ultrasound marker. Of the 203 contractions detected by ultrasound, 53% were associated with pressure events in the manometric reference channel; 86% of contractions had corresponding pressure events detectable somewhere in the antrum. Contractions that occluded the lumen were more likely to be associated with a pressure event in the manometric reference channel (P < 0.01) and to be of greater amplitude (P < 0.01) than non-lumen-occlusive contractions. We conclude that heterogeneous pressure event patterns in the antrum occur despite a stereotyped pattern of contraction propagation seen on ultrasound. Lumen occlusion is more likely to be associated with higher peak antral pressure events.
    AJP Gastrointestinal and Liver Physiology 07/2001; 281(1):G95-101. · 3.43 Impact Factor
  • Article: Long-term effects of pyloromyotomy on pyloric motility and gastric emptying in humans.
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    ABSTRACT: The aim of this study was to determine the long term effects of pyloromyotomy for infantile hypertrophic pyloric stenosis (IHPS) on gastric emptying and pyloric motility. Concurrent measurements of gastric emptying and antropyloroduodenal pressures were performed in six volunteers (aged 24-26 yr) who had had pyloromyotomy performed in infancy because of IHPS, and in six normal subjects. Subjects were studied on 2 days, once sitting and once in the left lateral position. Gastric emptying of 300 ml 25% dextrose labeled with 20 MBq 99mTc sulfur colloid was measured. Antropyloroduodenal motility was evaluated with a sleeve/multiple sidehole manometric assembly, which was also used to deliver an intraduodenal triglyceride infusion at 1.1 kcal/min for 60 min, starting 30 min after ingestion of the dextrose. In both body positions, gastric emptying and intragastric distribution of the drink did not differ between the two groups. In both groups and postures, the amount emptied was less during intraduodenal lipid infusion. The number (p<0.01) and amplitude (p<0.02) of isolated pyloric pressure waves (IPPWs) was greater in the control subjects, whereas basal pyloric pressure was greater in the pyloromyotomy subjects (p<0.02). In both groups, the rate of gastric emptying in the sitting position was related to the number of IPPWs (r> or =0.40, p<0.05), but not to basal pyloric pressure. These results indicate that, in adults who have had pyloromyotomy for IHPS in infancy, patterns of pyloric motility are abnormal; pyloric tone is higher, whereas the number and amplitude of phasic pyloric pressure waves are less. In contrast, the overall rate of gastric emptying of a nutrient liquid meal is normal. These observations are consistent with the concept that the stomach has the capacity to compensate for changes in pyloric motility to minimize effects on gastric emptying.
    The American Journal of Gastroenterology 02/2000; 95(1):92-100. · 7.28 Impact Factor
  • Article: The effect of hyperglycaemia on cerebral potentials evoked by rapid rectal distension in healthy humans.
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    ABSTRACT: Acute hyperglycaemia affects the perception of sensations arising from the gastrointestinal tract. The mechanisms responsible for this effect are unknown. Recordings of cerebral evoked potentials (EPs) can be used to assess the integrity of visceral afferent pathways. Our aim was to determine whether hyperglycaemia affects EPs elicited by rectal distension in healthy humans. Twelve healthy men, aged 19-31 years, were studied. A manometric catheter, incorporating a rectal balloon, was positioned 7-10 cm from the anal verge. Balloon distensions at both 'low' ( approximately 20 mL) and 'high' ( approximately 28 mL) volumes were performed, in a single-blind, randomized order, during both euglycaemia (4 mmol L-1) and hyperglycaemia (12 mmol L-1). EPs were recorded from a midline scalp electrode (Cz, International 10-20 system) and averaged for each series of 50 distensions. EP latencies and interpeak amplitudes were calculated. Polyphasic EPs were recorded in all but one subject. Although the blood glucose concentration had no significant effect on the latencies of the EP peaks elicited by either 'low'- or 'high'-volume balloon distension, the interpeak amplitude (P1-N1) was greater during hyperglycaemia than during euglycaemia at the 'low' balloon volume (6.3 +/- 1.2 microV vs. 4.8 +/- 1.0 microV, P < 0.05). The blood glucose concentration had no significant effect on the perception of rectal balloon distension. We conclude that in normal subjects acute hyperglycaemia increases the amplitude of the cerebral EP elicited by rectal balloon distension at low balloon volumes, suggesting that the effects of hyperglycaemia on gastrointestinal sensation may be mediated by central mechanisms.
    European Journal of Clinical Investigation 07/1999; 29(6):512-8. · 3.02 Impact Factor
  • Article: Effects of hyperglycemia on cortical response to esophageal distension in normal subjects.
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    ABSTRACT: Acute changes in the blood glucose concentration affect the intensity of gastrointestinal sensations. The aim of this study was to examine the effects of hyperglycemia on cortical potentials evoked by esophageal distension. In 16 healthy volunteers, a balloon was positioned in the lower esophagus. A series of 50 distensions was performed at both a lower volume (producing definite sensation) and a higher volume (producing unpleasant sensation), at blood glucose concentrations of 5 and 13 mmol/liter. Triphasic cortical potentials were recorded from a midline scalp electrode (Cz). During euglycemia, interpeak amplitudes were greater at the higher than the lower balloon volume (P < 0.005). At the lower balloon volume, the interpeak amplitudes were greater during hyperglycemia than euglycemia (P < 0.05). There was no effect of the blood glucose concentration on amplitude at the higher balloon volume. We conclude that in healthy subjects, the amplitude of the cortical response to moderate, but not unpleasant, esophageal distension is greater during hyperglycemia when compared to euglycemia. These observations are consistent with the concept of increased intensity of gut sensation during hyperglycemia.
    Digestive Diseases and Sciences 03/1999; 44(2):279-85. · 2.12 Impact Factor
  • Article: Effects of nitroglycerin on liquid gastric emptying and antropyloroduodenal motility.
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    ABSTRACT: The effects of the nitric oxide donor nitroglycerin on gastric emptying and antropyloroduodenal motility were evaluated in nine healthy male subjects (ages 19-36 yr). Antropyloroduodenal pressures were recorded with a manometric assembly that had nine side holes spanning the antrum and proximal duodenum and a pyloric sleeve sensor; gastric emptying was quantified scintigraphically. In each subject, the emptying of 300 ml of 25% glucose labeled with 99mTc was assessed on two separate days during intravenous infusion of either nitroglycerin (5 micrograms/min in 5% dextrose) or 5% dextrose (control). Studies were performed with the subject in the supine position; blood pressure and heart rate were monitored. Nitroglycerin had no significant effect on blood pressure or heart rate. Nitroglycerin slowed gastric emptying (P < 0.02), and this was associated with greater retention of the drink in the proximal stomach (P < 0.05). In both nitroglycerin and control studies, ingestion of the drink was associated with an increase in the number of isolated pyloric pressure waves (P < 0.05) and antral pressure wave sequences (P < 0.05). Nitroglycerin reduced the number of isolated pyloric pressure waves (P < 0.05), basal pyloric pressure (P < 0.05), and the number of antral pressure wave sequences (P < 0. 05), but not the total number of antral pressure waves. The rate of gastric emptying and the number of isolated pyloric pressure waves were inversely related during control (P = 0.03) and nitroglycerin (P < 0.05) infusions. We conclude that in normal subjects, 1) gastric emptying of 300 ml of 25% glucose is inversely related to the frequency of phasic pyloric pressure waves, and 2) nitroglycerin in a dose of 5 micrograms/min inhibits pyloric motility, alters the organization but not the number of antral pressure waves, and slows gastric emptying and intragastric distribution of 25% glucose.
    The American journal of physiology 11/1998; 275(5 Pt 1):G1173-8.
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    Article: Acute effects of therapeutic irradiation for prostatic carcinoma on anorectal function.
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    ABSTRACT: The incidence of anorectal symptoms after radiotherapy (RTH) for localised pelvic malignant disease is unclear. In addition, the effects of pelvic irradiation on both anorectal motility and sensory function are poorly defined. A prospective study was therefore performed on 35 patients (55-82 years of age) with localised prostatic carcinoma before and four to six weeks after RTH to assess its effects on anorectal function. Anorectal symptoms were assessed by questionnaire. Anorectal pressures at rest and in response to voluntary squeeze, rectal distension, and increases in intra-abdominal pressure were evaluated with perfused sleeve side hole manometry. Rectal sensation was tested during graded balloon distension. Rectal compliance was calculated by the pressure-volume relation obtained during the testing of rectal sensation. Ultrasound was used to determine anal sphincter structure and integrity. RTH had no effect on anal sphincter morphology. The frequency of defecation increased after RTH (7 (3-21) v 10 (3-56) bowel actions a week; p < 0.01). After RTH, 16 patients had faecal urgency and eight faecal incontinence, compared with five and one respectively before RTH (p < 0.01 for each). Basal and squeeze sleeve recorded pressures were reduced after RTH (54 (3) v 49 (3) mm Hg (p < 0.05) and 111 (8) v 102 (8) mm Hg (p < 0.01), before and after RTH respectively; means (SEM)). Rectal compliance was reduced after RTH (1.2 v 1.4 mm Hg/ml, p < 0.05). After RTH, threshold volumes for perception of rectal distension were lower in the 16 patients who either experienced faecal urgency for the first time (13 patients) or reported worsening of this symptom (three patients) compared with the remaining patients (34 (4) v 48 (5) ml respectively, p < 0.05). Faecal incontinence (23%) is a common problem four to six weeks after RTH for prostatic carcinoma and is associated with minor reductions in anal sphincter pressures. The high prevalence of faecal urgency in patients after RTH may be related to alterations in rectal perception of stool.
    Gut 07/1998; 43(1):123-7. · 10.11 Impact Factor
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    Article: Effect of glucose supplementation on appetite and the pyloric motor response to intraduodenal glucose and lipid.
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    ABSTRACT: The effects of different macronutrients on appetite and pyloric motility and the impact of short-term dietary glucose supplementation on these responses were evaluated. Ten males (aged 19-38 yr) received isocaloric (2.9 kcal/min) intraduodenal infusions of glucose and lipid while antropyloroduodenal motility and appetite were assessed by manometry and visual analog scales, respectively. Effects of each intraduodenal nutrient on appetite and motility were evaluated before and after 7 days of dietary supplementation with glucose (400 g daily). Initially, both nutrients caused a similar rise in pyloric tone, but intraduodenal lipid was a more potent stimulus of phasic pyloric motility (P = 0.05) and suppressed appetite more (P = 0.013) than intraduodenal glucose. After dietary glucose supplementation, the increase in pyloric tone during intraduodenal glucose was attenuated. Although intraduodenal lipid remained a more potent stimulant of phasic pyloric motility (P = 0.016), it no longer decreased appetite. We conclude that in healthy young males 1) intraduodenal infusion of lipid is a more potent stimulus of phasic pyloric motility and suppresses appetite more than intraduodenal glucose and 2) dietary glucose supplementation alters both the appetite suppressant effect of intraduodenal lipid and the pyloric motor response to intraduodenal glucose infusion.
    The American journal of physiology 05/1998; 274(4 Pt 1):G645-52.
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    Article: Acute hyperglycaemia affects anorectal motor and sensory function in normal subjects.
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    ABSTRACT: The pathogenesis of anorectal dysfunction, which occurs frequently in patients with diabetes mellitus, is poorly defined. Recent studies indicate that changes in the blood glucose concentration have a major reversible effect on gastrointestinal motor function. To determine the effects of physiological changes in blood glucose and hyperglycaemia on anorectal motor and sensory function in normal subjects. In eight normal subjects measurements of anorectal motility and sensation were performed on separate days while blood glucose concentrations were stabilised at 4, 8, and 12 mmol/l. Anorectal motor and sensory function was measured using a sleeve/sidehole catheter incorporating a balloon, and electromyography. The number of spontaneous anal relaxations was greater at 12 mmol/l than at 8 and 4 mmol/l glucose (p < 0.05 for both). Anal squeeze pressures were less at a blood glucose of 12 mmol/l when compared with 8 and 4 mmol/l (p < 0.05 for both). During rectal distension, residual anal pressures were not significantly different between the three blood glucose concentrations. Rectal compliance was greater (p < 0.05) at a blood glucose of 12 mmol/l when compared with 4 mmol/l. The threshold volume for initial perception of rectal distension was less at 12 mmol/l when compared with 4 mmol/l (40 (20-100) ml versus 10 (10-150) ml, p < 0.05). An acute elevation of blood glucose to 12 mmol/l inhibits internal and external anal sphincter function and increases rectal sensitivity in normal subjects. In contrast, physiological changes in blood glucose do not have a significant effect on anorectal motor and sensory function.
    Gut 11/1997; 41(4):494-9. · 10.11 Impact Factor
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    Article: Spatial patterns of fasting and fed antropyloric pressure waves in humans.
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    ABSTRACT: 1. Gastric mechanics were investigated by categorizing the temporal and spatial patterning of pressure waves associated with individual gastric contractions. 2. In twelve healthy volunteers, intraluminal pressures were monitored from nine side hole recording points spaced at 1.5 cm intervals along the antrum, pylorus and duodenum. 3. Pressure wave sequences that occurred during phase II fasting contractions (n = 221) and after food (n = 778) were evaluated. 4. The most common pattern of pressure wave onset along the antrum was a variable combination of antegrade, synchronous and retrograde propagation between side hole pairs. This variable pattern accounted for 42% of sequences after food, and 34% during fasting (P < 0.05). Other common pressure wave sequence patterns were: purely antegrade-29% after food and 42% during fasting (P < 0.05); purely synchronous-23% fed and 17% fasting; and purely retrograde-6% fed and 8% fasting. The length of sequences was shorter after food (P < 0.05). Some sequences 'skipped' individual recording points. 5. The spatial patterning of gastric pressure wave sequences is diverse, and may explain the differing mechanical outcomes among individual gastric contractions. 6. Better understanding of gastric mechanics may be gained from temporally precise correlations of luminal flows and pressures and gastric wall motion during individual gastric contraction sequences.
    The Journal of Physiology 09/1997; 503 ( Pt 2):455-62. · 4.72 Impact Factor
  • Article: Pyloric motor response to central and peripheral nitric oxide in the ferret.
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    ABSTRACT: This study has investigated the relative importance of central nervous and peripheral nitroxidergic mechanisms in the control of pyloric motility. In 10 urethane-anaesthetized ferrets, drugs were administered directly to the CNS via a 0.5-mm-diameter cannula inserted into the 4th ventricle, approximately at the obex. Drugs were also given directly to the upper GI tract by close intra-arterial (i.a.) injection at the coeliac axis. Antropyloroduodenal pressures were recorded with a five-channel sleeve/sidehole micromanometric assembly (1.35 x 1.75 mm o.d.), which was introduced via the duodenum. Pyloric motility was stimulated throughout the main part of each study with a continuous i.v. infusion of CCK-8 (30 pmol min-1). This infusion produced an immediate and sustained increase in tonic and phasic pyloric activity, and sustained abolition of antral pressure waves. CCK-8 also induced a duodenal motor response, but this was short-lived (11.4 +/- 7.9 min). Coeliac axis injection of the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) decreased phasic pyloric activity (from 330 +/- 35 to 148 +/- 21 mmHg min-1 after SNAP 5 micrograms, P < 0.01). By comparison central SNAP administration over the same dose range had no effect on CCK-stimulated pyloric motlity. Inhibition of endogenous NO synthase with L-Nitro Arginine Methyl Ester (L-NAME, 100 mg kg-1 close i.a.) caused a marked increase of phase pyloric motor activity from 349 +/- 59 to 1044 +/- 140 mmHg min-1 (P < 0.01). In addition, SNAP caused marked stimulation of pyloric tone from 2.6 +/- 0.5 to 13.1 +/- 2.8 mmHg (P < 0.01). Central nervous administration of L-NAME caused modest enhancement of phasic pyloric activity (248 +/- 31 to 283 +/- 32 mmHg min-1 P < 0.05) and pyloric tone (2.6 +/- 0.5 to 3.7 +/- 0.7 mmHg, P < 0.05). Our data indicate that motor activity of the ferret pylorus is potently modulated by NO released within the upper gut. Additionally, there is potential for modulation of pyloric motility by central nervous system production of NO.
    Neurogastroenterology and Motility 09/1997; 9(3):167-75. · 3.41 Impact Factor
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    Article: Relation between postprandial satiation and antral area in normal subjects.
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    ABSTRACT: The factors influencing appetite in humans are poorly understood. There is a weak relation between appetite and gastric emptying in normal subjects. Recent studies have shown that fasting and postprandial antral areas increase in patients with functional dyspepsia compared with normal subjects. We evaluated the hypothesis that antral area, and hence antral distention, is a significant determinant of postprandial fullness. Fourteen normal subjects had simultaneous measurements of gastric emptying by scintigraphy and antral area by ultrasound after ingestion of 350 mL 20% glucose. Fullness and hunger were assessed by visual analog scales. Measurements of the gastric-emptying half time (t1/2) by scintigraphy and ultrasound were not significantly different (129.6 +/- 11.8 min compared with 115.6 +/- 11.4 min). Fullness increased (P < 0.001) and hunger decreased (P < 0.001) after the drink. Both fullness and the magnitude of the increase in fullness after the drink were related to antral area (r > 0.56, P < 0.05), the increase in antral area (r > 0.59, P < 0.05), and the scintigraphic content of the distal stomach (r > 0.57, P < 0.05), but not to the ultrasound or scintigraphic t1/2 values. In contrast, hunger and the magnitude of the decrease in hunger after the drink were not related to either antral area, the increase in antral area, or the rate of gastric emptying. We conclude that postprandial fullness, but not hunger, was closely related to antral distention in normal subjects.
    American Journal of Clinical Nutrition 07/1997; 66(1):127-32. · 6.67 Impact Factor
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    Article: Hyperglycemia affects gastric electrical rhythm and nausea during intraduodenal triglyceride infusion.
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    ABSTRACT: Hyperglycemia slows gastric emptying and increases the intensity of perception of gastric distension during fasting and small intestinal nutrient stimulation. In order to examine the possibility that abnormalities of gastric electrical rhythm may be associated with the effects of hyperglycemia, the gastric electrical rhythm (cutaneous electrogastrogram) and the perception rating scores for upper gastrointestinal sensations (visual analog scale) were examined. Studies were performed during intraduodenal triglyceride infusion in 10 healthy volunteers under euglycemic and hyperglycemic (approximately 15 mmol/liter) conditions. During fasting, hyperglycemia had no effect on either gastric electrical rhythm or sensation. Intraduodenal triglyceride infusion was associated with an increase in bradygastria (<2.4 cpm) during both euglycemia (33 +/- 9%) and hyperglycemia (36 +/- 10%, P < 0.05 vs baseline for each). During intraduodenal triglyceride infusion, tachygastria (>3.6 cpm) was more prevalent during hyperglycemia when compared to euglycemia (25 +/- 10% vs 1 +/- 1%, P < 0.05) and the perception rating scores for nausea and abdominal discomfort were greater during hyperglycemia (P < 0.05 for both). The intensity of nausea correlated with the proportion of time spent in tachygastria (r = 0.64, P < 0.01). These data are consistent with the concept that postprandial upper gastrointestinal symptoms in patients with diabetes mellitus may be modulated by the blood glucose concentration.
    Digestive Diseases and Sciences 04/1997; 42(3):568-75. · 2.12 Impact Factor
  • Article: Hyperglycemia affects proximal gastric motor and sensory function during small intestinal triglyceride infusion.
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    ABSTRACT: Hyperglycemia slows gastric emptying in normal individuals and patients with diabetes mellitus and may affect both somatic and visceral sensation. The effects of hyperglycemia on proximal gastric motility and sensation during intraduodenal infusion of a triglyceride emulsion were evaluated using a barostat in six normal subjects during euglycemia and hyperglycemia (approximately 15 mmol/l). Isobaric distension induced greater bag volumes during hyperglycemia compared with euglycemia at 3 (452 +/- 26 vs. 343 +/- 12 ml, P < 0.05) and 4 mmHg (600 +/- 55 vs. 497 +/- 50 ml, P < 0.05) above basal pressure. During isovolumetric distension, intrabag pressure was less during hyperglycemia at 500 (2.5 +/- 0.3 vs. 3.5 +/- 0.5 mmHg above basal pressure, P < 0.05) and 600 ml (3.0 +/- 0.4 vs. 4.5 +/- 0.5 mmHg above basal pressure, P < 0.05). Perception of nausea (P < 0.05) and fullness (P < 0.05) was increased during hyperglycemia compared with euglycemia. We conclude that hyperglycemia 1) reduces proximal gastric tone during intraduodenal triglyceride infusion, an effect that may contribute to delayed gastric emptying, and 2) increases the intensity of nausea and fullness during intraduodenal triglyceride infusion and proximal gastric distension, indicative of an effect on visceral sensation.
    The American journal of physiology 11/1996; 271(5 Pt 1):G814-9.
  • Article: Disturbances in anorectal function in patients with diabetes mellitus and faecal incontinence.
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    ABSTRACT: The pathophysiology of faecal incontinence in diabetes mellitus is poorly understood. The study was designed to document the anorectal dysfunctions in diabetic patients with faecal incontinence. Multiport anorectal manometry and electromyography were done in 11 diabetic patients with faecal incontinence and in 20 healthy controls. Basal and squeeze pressures were reduced (P < 0.05) in the diabetic patients compared with the control subjects. During basal recording six patients showed regular oscillations in anal electrical activity and pressure with an amplitude of 10-40 (median: 25) cmH2O and a frequency of 6-10 (median: 8) min-1. Nine patients also exhibited spontaneous transient anal relaxations with an amplitude of 15-50 (median: 40) cmH2O and a duration of 15-720 (median: 60)s, and in six of them leakage occurred as the anal pressure fell below the rectal pressure. None of the control subjects showed oscillation or spontaneous relaxations. In patients there was a greater tendency for repetitive rectal contractions in response to rectal distension and reduced rectal compliance (P < 0.01). During rectal distension four patients showed no anal relaxation, and in the remainder relaxation occurred at an abnormally high threshold. However, the residual pressures were lower (P < 0.05) than in control subjects and often fell below rectal pressure, whereupon leakage occurred. There was no significant difference in the distension thresholds for rectal sensation between patients and control subjects, but in 9/11 patients the perception of rectal sensation was delayed by more than 2s (P < 0.05). These results indicate that aetiology of faecal incontinence in diabetic patients is multifactorial and, suggest for the first time, that instability of the internal sphincter probably plays a major role.
    European Journal of Gastroenterology & Hepatology 10/1996; 8(10):1007-12. · 1.76 Impact Factor
  • Article: Appetite regulation by carbohydrate: role of blood glucose and gastrointestinal hormones.
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    ABSTRACT: To investigate the mechanisms by which intestinal carbohydrate affects eating behavior, seven fasted, healthy male volunteers received intraduodenal infusions of glucose or saline over a 90-min period while blood glucose levels were matched by use of intravenous glucose and saline infusions. A second study examined the effect of intraduodenal glucose on eating behavior when the gastrointestinal hormone response was inhibited by intravenous octreotide. Intravenous glucose infusion did not affect hunger or satiety. In contrast, intraduodenal infusion of glucose suppressed hunger, increased fullness and satiety ratings, reduced energy intake, and resulted in higher plasma insulin responses compared with the intravenous glucose infusion. Octreotide abolished the plasma insulin response to intraduodenal glucose and reversed the changes in ratings and eating behavior. This study has shown that the effects of intestinal glucose on appetite are not mediated via an increase in blood glucose but are likely to reflect small intestinal stimulation of release of either insulin or intestinal incretins.
    The American journal of physiology 09/1996; 271(2 Pt 1):E209-14.
  • Article: A retrospective study of the effects of pelvic irradiation for gynecological cancer on anorectal function.
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    ABSTRACT: To evaluate the prevalence of anorectal dysfunction following therapeutic pelvic irradiation. Anorectal function was evaluated in 15 randomly selected patients (aged 47-84 years) who had received pelvic irradiation for treatment of carcinoma of the uterine body and cervix 5 and 10 years earlier. The following parameters were assessed in each patient: (a) anorectal symptoms (questionnaire), (b) anorectal pressures at rest and in response to rectal distension, voluntary squeeze, and increases in intraabdominal pressure (multiport anorectal manometry with concurrent electromyography of the anal sphincters), (c) rectal sensation (rectal balloon distension) and, (d) anal sphincteric morphology (ultrasound). Results were compared with those obtained in nine female control subjects. Ten of the 15 patients had urgency of defecation and 4 also suffered fecal incontinence. Basal anorectal pressures measured just proximal to the anal canal (p = 0.05) and anorectal pressures generated in response to voluntary squeeze measured at the anal canal were less (p < 0.01) in the patients. The fall in anal pressures in response to rectal distension was greater in the patients (p < 0.05) and the desire to defecate occurred at lower rectal volumes (p < 0.05). The slope of the pressure/volume relationship in response to rectal distension was greater (p < 0.05) in the patients, suggestive of a reduction in rectal compliance. In 14 of the 15 patients at least one parameter of anorectal motor function was outside the control range. There was no difference in the thickness of the anal sphincters between the two groups. Abnormal anorectal function occurs frequently following pelvic irradiation for gynecological malignant diseases and is characterized by multiple dysfunctions including weakness of the external anal sphincter, stiffness of the rectal wall, and a consequent increase in rectal sensitivity.
    International Journal of Radiation OncologyBiologyPhysics 08/1996; 35(5):1003-10. · 4.11 Impact Factor
  • Article: Effects of glyceryl trinitrate on the pyloric motor response to intraduodenal triglyceride infusion in humans.
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    ABSTRACT: The retardation of gastric emptying induced by infusion of triglyceride into the small intestine is associated with suppression of antral pressure waves and stimulation of basal pyloric tone in combination with phasic pressure waves localized to the pylorus. The role of nitric oxide (NO) mechanisms in the control of pyloric motility was evaluated in 12 healthy male subjects (21-43 years), using the NO donor glyceryl trinitrate (GTN). Antropyloric pressures were measured with a manometric assembly incorporating nine sideholes, spanning the antrum and proximal duodenum, and a pyloric sleeve sensor. On separate days, an intraduodenal triglyceride infusion (10% intralipid at 1 mL min-1) was started during antral phase I activity and continued for 60 min. On one of the days GTN (600 micrograms) was given sublingually 20 min after start of the triglyceride infusion. The tonic pyloric motor response to triglyceride [5.6 (SEM 0.8,) vs. 2.7 (1.3) mmHg, P < 0.001] and both the number 3.2 (0.2) vs. 2.2 (0.2) min-1, P < 0.05] and amplitude [40 (4) vs. 27 (5) mmHg, P < 0.05] of phasic isolated pyloric pressure waves were reduced by GTN. These observations suggest that NO mechanisms are involved in the regulation of pyloric motor activity in humans.
    European Journal of Clinical Investigation 08/1996; 26(8):657-64. · 3.02 Impact Factor
  • Article: Hyperglycaemia affects proximal gastric motor and sensory function in normal subjects.
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    ABSTRACT: Hyperglycaemia delays gastric emptying in normal subjects and patients with diabetes mellitus by uncertain mechanisms and may affect the perception of somatic sensations. The effects of hyperglycaemia on the motor function of the proximal stomach and the perception of gastric distension were evaluated in normal subjects. Paired studies were performed in randomized order in 10 healthy volunteers on separate days during euglycaemia and hyperglycaemia (blood glucose approximately equal to 15 mmol/l). With a barostat and a balloon positioned in the proximal stomach, tasting subjects underwent a stepwise gastric distension. Each 2 mmHg step was maintained at a constant pressure for 2 min. The volume of the barostat balloon was measured and perception of the sensations of fullness, desire to belch, nausea, abdominal discomfort and hunger was scored at each step. Hyperglycaemia was associated with an increase in proximal gastric compliance (P < 0.01) evident from 2 mmHg above basal intragastric pressure. Perception scores for the sensations of nausea and desire to belch were greater during hyperglycaemia than euglycaemia (P < 0.05) in relation to both pressure at each step and volume. Hyperglycaemia did not affect perception of the sensations of abdominal discomfort, fullness or hunger. Hyperglycaemia increases proximal gastric compliance, reflecting a reduction in gastric tone. This may contribute to the previously observed delay in gastric emptying associated with hyperglycaemia. Hyperglycaemia appears to increase the perception of some of the sensations induced by gastric distension.
    European Journal of Gastroenterology & Hepatology 04/1996; 8(3):211-7. · 1.76 Impact Factor
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    Article: Effects of cisapride on gastric emptying of oil and aqueous meal components, hunger, and fullness.
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    ABSTRACT: To evaluate the effects of cisapride on gastric emptying of extracellular fat and hunger and fullness 10 volunteers consumed a meal consisting of 60 ml technectium-99m (99mTc)-V-thiocyanate labelled olive oil and 290 ml indium-113m (113mIn) labelled soup after taking cisapride (10 mg four times daily orally) and placebo, each for four days, in randomised, double blind fashion. Gastric emptying was quantified scintigraphically. Hunger and fullness before and after the meal were evaluated using visual analogue scales. Cisapride accelerated gastric emptying of oil and aqueous components by reducing the lag phase mean (SEM) (20.3 (7.0) min v 40.7 (4.1) min (p < 0.05) for oil and 4.1 (2.5) min v 10.0 (3.1) min (p < 0.05) for aqueous). Cisapride had no effect on the post-lag emptying rate of oil. Treatment with cisapride was associated with reduced retention of oil in the proximal stomach (p < 0.05). Subjects were more hungry before ingestion of the meal while receiving cisapride (6.7 (0.9) v 3.9 (0.7), p < 0.001). The scores for hunger at 120 and 180 minutes were inversely related to gastric emptying of oil on both cisapride (r > -0.62, p < 0.05) and placebo (r > -0.86, p < 0.001). Fullness increased after the meal while receiving placebo (p < 0.01), but not cisapride and postprandial fullness was less with cisapride at (30 min; 0.4 (0.3) v 3.3 (1.0), p < 0.05). With placebo, but not cisapride, the score for fullness at 15 minutes was inversely related to emptying of the aqueous phase (r = 0.68, p < 0.05). These results show that in normal volunteers after ingestion of an oil/aqueous meal: (a) postprandial hunger is inversely related to gastric emptying of oil, while fullness is inversely related to gastric emptying of the aqueous phase, (b) cisapride affects the intragastric distribution and accelerates gastric emptying of both oil and aqueous meal components, and (c) cisapride increases preprandial hunger and reduces postprandial fullness.
    Gut 03/1996; 38(3):310-5. · 10.11 Impact Factor

Institutions

  • 1995–2004
    • Royal Adelaide Hospital
      • Department of Medicine
      Adelaide, South Australia, Australia
  • 1996
    • University of Adelaide
      • Discipline of Medicine
      Adelaide, South Australia, Australia
  • 1994
    • Universitair Medisch Centrum Utrecht
      • Department of Surgery
      Utrecht, Provincie Utrecht, Netherlands
  • 1991–1994
    • Northern General Hospital
      Sheffield, ENG, United Kingdom
  • 1988–1993
    • The University of Sheffield
      Sheffield, ENG, United Kingdom
  • 1989–1990
    • Royal Hallamshire Hospital
      Sheffield, ENG, United Kingdom