Biomedical subjects

D F Evans

Publications and source records attributed to D F Evans.

At least 37 records · Page 2Linked to original sources

PubMed1997

Daytime and night time motor activity of the small bowel after solid meals of different caloric value in humans.

BACKGROUND: Meals disrupt the interdigestive pattern of small bowel motor activity and convert it into the postprandial pattern. Previous studies have shown that duration of postprandial motor activity depends on the caloric value of a meal, but results from two recent human studies suggested that there is a caloric ceiling, above which an additional increase in the caloric load fails to prolong the postprandial period further. AIM: To investigate the hypothesis of a caloric ceiling by studying daytime motor activity of the human small bowel in response to five solid meals, covering a wide range of calories. METHODS: Eight healthy male volunteers underwent five separate, ambulatory small bowel manometry studies and had a total of 80 meals. For lunch, volunteers ate between one and five portions of a solid meal (220, 440, 660, 880, or 1100 kcal). Ten hours later and 30 minutes before they went to bed, they ate either two or four portions of the same meal (440 kcal or 880 kcal). Recordings were analysed visually for phase III of the migrating motor complex and a validated computer program calculated incidence and amplitude of contractions. RESULTS: Apart from two versus three portions (440 kcal v 660 kcal), postprandial motor activity was significantly prolonged by each 220 kcal increase in the caloric load of the lunch (168 (SEM 14), 305 (22), 298 (23), 368 (36), and 398 (38) min). Mean incidence of contractions was significantly different only between the two extremes tested: 220 kcal and 1100 kcal (2.9 (0.3) v 4.5 (0.6) min-1). Amplitude of contractions did not depend on meal size. Daytime and night time postprandial activity were not significantly different. This was true for duration of fed activity, as well as mean incidence and amplitude of contractions during the postprandial period. CONCLUSION: Caloric value of a meal regulates duration of the fed activity in the human small bowel over a wide range of calories, and-for caloric loads up to 1100 kcal-there is no maximum duration of postprandial motor activity. Furthermore the postprandial small bowel motor activity is very similar between daytime and night time.

Adult↗

PubMed1997

Oesophageal acid and salivary secretion: is chewing gum a treatment option for gastro-oesophageal reflux?

The presence of acid in the oesophagus has been shown to stimulate salivary secretion, but the relevance of this oesophago-salivary reflex for acid clearance in physiological and pathological gastro-oesophageal reflux (GOR) is unknown. This study was designed to investigate the interrelation between oesophageal acid and both resting and stimulated salivary secretion. In 10 healthy volunteers, the acid clearance times after bolus infusion of 20 ml of 0.1 N hydrochloric acid were measured by means of ambulatory oesophageal pH monitoring. With a constant swallowing rate and resting salivary flow, the acid clearance time was significantly longer with dry as opposed to wet swallows (12.6 +/- 2.6 vs. 6.9 +/- 1.9 min; p = 0.01). When the salivary flow was doubled by chewing a gum base (26.0 +/- 3.4 vs. 13.2 +/- 2.0 ml/15 min; p = 0.005), the acid clearance time was markedly shortened (6.9 +/- 1.9 vs. 2.3 +/- 0.2 min; p = 0.02). As compared with water control, salivary flow, pH, and protein content were not affected by a bolus infusion of hydrochloric acid. This was true both for resting and gum-stimulated salivary secretion. Our study suggests that an oesophago-salivary reflex becomes effective only in prolonged episodes of GOR. This may explain why the water brash phenomenon is not regularly experienced by all reflux patients. Our study also suggests that chewing gum might be a non-pharmacological treatment option for some patients with symptomatic GOR.

Adult↗

PubMed1997

Comparison of the small bowel motor response to solid and liquid meals in man.

Interdigestive motor activity has been studied extensively both in the human and canine small intestine. The more irregular postprandial pattern, however, has rarely been studied. In particular, physiological studies in humans are lacking. Thus it is unknown whether the physical state of a meal affects the duration of the postprandial motor activity or contractile activity during the postprandial period. 8 healthy male volunteers, aged 19-38 years, underwent a single ambulatory 24-hour manometry study. During the study, volunteers had two physiological meals. The solid meal consisted of pasta with vegetables, and the liquid meal was a vanilla milk drink. The two meals were both palatable, isocaloric (660 kcal) and had an identical fat content (32%). Recordings were analyzed visually for phase III of the migrating motor complex and a validated computer program calculated the mean frequency and amplitude of contractions as well as the mean area under the curve (AUC). The postprandial period was significantly shorter after the liquid meal compared to the solid meal (196 +/- 43 vs. 298 +/- 23 min; p < 0.04). During the postprandial period, the mean incidence of contractions (2.0 +/- 0.5 vs. 3.7 +/- 0.4 min(-1); p < 0.02) and the mean AUC (132 +/- 32 vs. 236 +/- 27 mm Hg x s x min(-1); p < 0.02) were significantly lower after the liquid meal. The mean amplitude of contractions during the total postprandial period, however, was not significantly different between the two test meals (19.3 +/- 0.6 vs. 18.6 +/- 0.8 mm Hg). We conclude that human small bowel motor activity differs markedly between solid and liquid meals. Thus the postprandial pattern persists longer after solid meals, and this may have been due to the slower gastric emptying of solids as opposed to liquids. Furthermore the small bowel contracts far more frequently after solid meals.

Adult↗

PubMed1996

A study of the association between gastro-oesophageal reflux and palatal dental erosion.

Thirty-six patients aged 15-74 with palatal dental erosion where the aetiology was unclear were investigated for gastro-oesophageal reflux. Ten subjects without symptoms of reflux or palatal erosion acted as controls. Distal and proximal oesophageal reflux were measured over 24 hours by dual channel antimony electrodes. Oral pH was measured simultaneously over the same period by a radio-telemetry capsule held palatally in a vacuum formed splint. Data were logged onto two portable digitable recorders. Twenty-three patients (64%) with palatal erosion had pathological gastro-oesophageal reflux compared with standard criteria. More than 4% of the total percentage time that the pH is less than 4 in the distal oesophagus is internationally recognised by gastroenterologists as representing a pathological level of reflux. The median percentage time < pH 4 in the distal oesophagus for these patients was 5.7%, in the proximal oesophagus, pH 4 was 0.5% and pH < 5 was 3.1%. In the mouth, the results for the percentage time that the pH < 5.5 was 0.3% and < 6 was 4.4%. A relationship was observed between the pH < 4 in the distal oesophagus and the mouth pH < 5.5 (r = 0.47, P = 0.002) and pH < 6 (r = 0.34, p = 0.02). There was a relationship between oral acid exposure time pH < 6 and the tooth wear index (r = 0.37, P = 0.01). These results show that gastro-oesophageal reflux is strongly associated with palatal erosion and that some patients presenting with palatal dental erosion should be assessed for gastro-oesophageal reflux as a possible cause, even in the absence of clinical symptoms of reflux.

Adolescent↗

PubMed1996

Antireflux operations at flexible endoscopy using endoluminal stitching techniques: an experimental study.

BACKGROUND: Three antireflux operations-gastroplasty, fundoplication, and anterior gastropexy-were developed for performance at flexible endoscopy without laparotomy or laparoscopy. METHODS: An endoscopic sewing machine mounted on a standard gastroscope, endoscopic knotting devices, overtube, and nylon thread were used to perform these operations in adult beagle dogs. RESULTS: Gastroplasty (n = 10) was accomplished by suturing the anterior and posterior wall of the stomach to create a gastric tube (neoesophagus) along the lesser curve. An anatomic arrangement similar to fundoplication (n = 6) was achieved by invaginating the esophagus and fixing it to the stomach 2 cm distal to the cardioesophageal junction. Anterior gastropexy (n = 6) was performed using a technique similar to that used in creating percutaneous gastrostomies. There was no mortality. Ninety percent of sutures were seen at repeat endoscopy at 4 to 8 week intervals. The gastroplasty group was selected for more extensive evaluation. Manometry using a three-channel perfused catheter system before and after the procedures showed an increase in the lower esophageal sphincter pressure (preoperative median 4.6 mm Hg; post-operative median 13.33 mm Hg, p = 0.008) and cardiac yield pressures (preoperative median 10 mm Hg; postoperative median 19 mm Hg, p = 0.007). CONCLUSIONS: This study demonstrates the feasibility of performing antireflux operations at flexible endoscopy, without laparoscopy or laparotomy, by use of endoluminal suturing techniques.

Animals↗

PubMed1996

The relationship between gastro-oesophageal reflux disease and dental erosion.

It is well known that acid regurgitated from the stomach into the mouth will erode teeth. Conditions such as anorexia and bulimia nervosa, chronic alcoholism and gastric disturbances cause palatal dental erosion. The common factor in these conditions is the role played by the stomach and oesophagus in the acid movement. Acid moving through the lower oesophageal sphincter into the oesophagus is described as gastro-oesophageal reflux (GOR). In some patients the acid movement becomes chronic, painful and requires treatment and is termed gastro-oesophageal reflux disease (GORD). It is felt by many gastroenterologists that GORD is a failure of the anti-reflux mechanism, which is predominantly controlled by the lower oesophageal sphincter (LOS). Regurgitation is the reflux of gastric juice through the upper oesophageal sphincter and into the oral cavity. Once the acid has reached the mouth the potential exists for damage to the teeth. This paper reviews the role of GOR, GORD and regurgitation in the aetiology of dental erosion.

Esophagogastric Junction↗

PubMed1996

The effect of different types of exercise on gastro-oesophageal reflux.

Sportsmen and women frequently experience abdominal and chest pain during exertion. The symptoms could be cardiac but may be caused by gastro-oesophageal reflux (GOR). The aim of our study was to investigate the effect of the two activities on GOR in 17 fit, healthy adults. GOR, assessed by intraoesophageal pH, was recorded on portable monitoring equipment before, during and after rowing and running. GOR was also measured after a light meal to simulate pre-training hydration. Three studies were performed: rowing, fasted running, and post-prandial running. GOR was infrequent before exercise, being seen in only 2 subjects. However, GOR was induced in 70% of rowers, 45% of fasted runners, and 90 % of fed runners during and immediately after exercise. The presence of food in the stomach greatly increased the amount of reflux during post-prandial running, (p < 0.006 against control) but reflux was also significantly higher in those who refluxed during fasted running (p < 0.03) and rowing (p < 0.08). There was no statistical difference in the amount of GOR between the two exercise periods. This study shows that both running and rowing induce significant amounts of GOR in a normally asymptomatic group of athletes. GOR should be considered in the investigation of exertional chest pain in patients attending a sports clinic.

Adult↗

PubMed1995

Physiological and symptomatic outcome after laparoscopic gastric fundoplication.

The complications of open antireflux operations may be reduced by laparoscopic techniques. Fifteen patients of median age 42 (range 16-79) years with gastro-oesophageal reflux underwent laparoscopic fundoplication. Preoperative and postoperative assessment was by clinical scoring, oesophageal pH measurement and manometry. Median (range) operating time was 115 (60-210) min and hospital stay 3 (1-6) days, with no conversions to open operation and only one minor wound infection. Four patients had occasional reflux symptoms on postoperative assessment at a median of 7 weeks and nine had occasional dysphagia. Median DeMeester symptom scores improved from 4 to 1.5 (P = 0.001). There were significant increases in both lower oesophageal sphincter pressure and length. The nocturnal proportion of time at pH < 4 decreased from 9.6 to 0.05 per cent (P = 0.02), although the drop in total proportion of time at pH < 4 (10.4 to 2.2 per cent) was not statistically significant (P = 0.08). Early objective results of laparoscopic fundoplication show improved symptoms, decreased acid reflux and altered lower sphincter function. The procedure combines the benefits of early mobilization and reduced morbidity with the efficacy of the traditional open operation.

Adolescent↗

PubMed1995

Alkaline gastro-oesophageal reflux: dual probe pH monitoring.

Although the aetiology of Barrett's oesophagus or columnar line oesophagus (CLO), remains unknown, bile reflux has been implicated as a factor in its pathogenesis. This study aimed to detect alkaline reflux in gastro-oesophageal reflux patients using dual probe pH monitoring. Thirty patients with histologically diagnosed CLO, 15 age and sex matched patients with oesophagitis (grade 1-3), and 15 healthy volunteers were studied by dual probe, 18 hour pH monitoring and analysis of the bile acid content of oesophageal refluxate. Total acid exposure and acid exposure in the upright and supine postures were greater in CLO subjects than in oesophagitis patients and controls. Furthermore, the number of reflux episodes lasting more than five minutes and the duration of the longest reflux episode were significantly greater in the CLO subjects than the oesophagitis and control subjects. Nine subjects with CLO and oesophagitis, however, were not identified as refluxers, although six had a bile acid concentration in their oesophageal aspirate higher than the 95th centile value of the controls. There was no correlation between the oesophageal pH and the bile acid contents of refluxate. It is concluded that dual probe pH monitoring is not useful in detecting alkaline refluxers. pH monitoring, although the only subjective test available to identify acid refluxers, is not a sufficiently sensitive test with which to define alkaline reflux.

Barrett Esophagus↗

PubMed1995

The effect of barium sulphate on small bowel motility in man.

OBJECTIVE: To investigate the effect of barium sulphate on small bowel motor activity. METHODS: Nine healthy male volunteers underwent two separate, ambulatory 24 h manometry studies. Jejunal motor activity was recorded during fasting and after ingestion of 300 ml volumes of barium, water or a glucose solution (1380 kJ). Recordings were analysed visually for recurrence of phase III of the migrating motor complex, and a validated computer program was used to calculate the incidence and amplitude of contractions. RESULTS: Phase III reappeared 71 +/- 10 min after ingestion of barium sulphate. This interval was not significantly different after the intake of water (60 +/- 8 min) or in the fasted state (88 +/- 21 min), but it was significantly shorter than after ingestion of a glucose solution (136 +/- 17 min). The mean incidence of contractions after ingestion of barium was 3.0 +/- 0.5/min. This was significantly higher than that observed after water (1.9 +/- 0.4/min) and also significantly higher than during fasting (1.5 +/- 0.3/min), but not significantly different from the incidence of contractions after ingestion of a glucose solution (2.2 +/- 0.4/min). The mean amplitude of contractions after ingestion of barium was 24.2 +/- 1.4 mmHg. This was significantly higher than the amplitude of contractions during fasting (19.5 +/- 1.0 mmHg), but not significantly different from that after water intake (23.7 +/- 1.3 mmHg) or after ingestion of a glucose solution (21.4 +/- 1.3 mmHg). CONCLUSION: Small bowel motor activity after ingestion of barium sulphate differs distinctly both from the interdigestive and from the postprandial motor pattern. Barium suspensions do not interrupt the migrating motor complex with a typical 'fed' pattern, but contractions are more frequent after ingestion of barium than after the intake of water and are both more frequent and of greater force than the contractions observed during the fasted state.

Adult↗

PubMed1994

Daytime ingestion of alcohol alters nighttime jejunal motility in man.

We studied the effects of acute ingestion of intoxicating doses of alcohol on jejunal motility in six male volunteers ages 24-45 who had two 24-hr ambulatory manometries, one week apart, that each included three standardized meals with either red wine (0.6 g of alcohol/kg) or dealcoholized wine. Breath alcohol was measured at regular intervals for 3 hr following alcohol. The results show that the MMC cycle was significantly (P < 0.01) shorter during the night than during the day in the "nonalcohol" group but not in the "alcohol" group and that the amplitude of contractions was higher during the night than the day in the alcohol group (P < 0.01). All meals interrupted the MMC and induced a fed pattern. After the 300-kcal liquid meal, the duration of the fed pattern was shorter (P < 0.01), with a lower motility index (P < 0.01) and fewer contractions (P < 0.01), than following the two 600-kcal meals. The number of clustered contractions occurring in the postprandial period was lower in the alcohol group than in the nonalcohol group. After the three alcohol doses, a breath alcohol peak was reached in 20-60 min, and in all subjects, breath alcohol fell below 22 micrograms/100 ml after the third hour. This study showed that alcohol had only minor effects on postprandial contractile activity but abolished the circadian variation of the MMC normally seen in healthy subjects. The fact that breath alcohol was low by the time of onset of sleep, suggests that the effects on the MMC may be mediated through central rather than local mechanisms.

Adult↗

PubMed1993

Long-range attractive force between hydrophobic surfaces observed by atomic force microscopy.

There is evidence from atomic force microscopy for a long-range attractive force between hydrophobic surfaces that is virtually identical to that observed with the surface forces apparatus. This force is present in the nonaqueous solvent ethylene glycol. A possible molecular mechanism involves in-plane polarized domains of solid-like monolayers adsorbed on mica, and a theoretical model has been developed that accounts for many of the observations.

Ethylene Glycol↗

PubMed1993

Proximal colonic response and gastrointestinal transit after high and low fat meals.

The fat component of meals has been thought to make a major contribution to the colonic response to feeding. We have combined gamma scintigraphy and radiotelemetry to noninvasively study the response of the normally inaccessible proximal colon after ingestion of either a high or low fat meal. Separate studies were performed to measure the rate of passage of the same meals through the whole gut. Gastric emptying and small bowel transit of the two meals to the colon was similar, 50% of meal marker reaching the ascending colon 4.8 +/- 0.2 and 4.5 +/- 0.3 hr after the high and low fat meals respectively (N = 8, difference not significant). The low fat meal caused a consistent increase in motility index, which rose from a basal value of 1.0 +/- 0.3 to 2.6 +/- 0.7 mm Hg in the 2 hr after the meal (N = 8, P < 0.01). Response to the high fat meal was less consistent, motility index increasing from 1.6 +/- 0.6 basally to 2.3 +/- 0.7 mm Hg postprandially (N = 8, P = 0.21). Despite these increases in motor activity there was no net caudal propulsion of colonic contents after either meal. The geometric center was comparable, being 3.2 +/- 0.4 and 3.7 +/- 0.4 before the high and low fat meals. This did not change significantly after either meal, being then 3.5 +/- 0.4 and 3.6 +/- 0.4 2 hr after the high and low fat meals, respectively. We conclude that in normal subjects equicaloric high and low fat meals transit the whole gut at a similar rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Cisapride in the treatment of gastro-oesophageal reflux disease.

Prokinetic agents are being used increasingly in medical therapy for gastro-oesophageal reflux disease (GERD). This study examined the effect of 10 mg q.d.s., oral cisapride, or placebo, taken for 12 weeks, on 48 patients with symptoms and endoscopic evidence of GERD. Objective evaluation of benefit was obtained by endoscopy and biopsy, oesophageal manometry, acid reflux provocation test and 24-h oesophageal pH monitoring. Cisapride significantly increased lower oesophageal sphincter pressure (P = 0.003) against baseline and also against placebo, in patients (n = 9) with an hypotensive lower oesophageal sphincter pressure (P < 0.01). The frequency of dyspeptic symptoms was significantly improved in the cisapride group (P = 0.03). Antacid intake, global evaluation of symptoms and a VAS score for symptoms were all better than placebo but failed to reach significance (global evaluation by patients, P = 0.07). Overall, there was no significant improvement in oesophagitis at either 6 weeks (P < 0.05 > 0.3) or 12 weeks (P = 0.07). However, if patients with grades I and II oesophagitis at entry were excluded, cisapride had a significantly greater effect than placebo, 6 weeks (P = 0.05), 12 weeks (P = 0.04). In those with oesophageal ulceration, cisapride was significantly more effective than placebo in inducing healing. Gastro-oesophageal reflux was very variable on both 24-h pH monitoring and acid reflux provocation test. In spite of a 50% decrease in acid exposure on 24-h pH monitoring (cisapride group, mean % pH < 4 day: entry 18.9%, 12 weeks 9.6%), there were no significant intra- or intergroup differences for percentage of time < pH 4, or frequency and duration of episodes, neither pre- or post-prandially, day or night, except for the number of post-prandial episodes during acid reflux provocation tests, which decreased significantly more with cisapride than with placebo (P < 0.05). Thus, oral cisapride when taken for 12 weeks promoted healing of oesophagitis and improved symptoms in patients with GERD; although an increase in lower oesophageal sphincter pressure was observed and a reduction in acid reflux was measured, no significant decrease of acid exposure was seen.

Adult↗

PubMed1993

Prolonged monitoring of the upper gastrointestinal tract using echo planar magnetic resonance imaging.

Upper gastrointestinal motility and transit has been studied in five human volunteers with the ultra high speed, magnetic resonance imaging (MRI) technique MBEST (Modulus Blipped Echo-planar Single pulse Technique), a variant of echo planar imaging. Snapshot images requiring a data acquisition time of only 64-128 msec allowed visualisation of peristalsis in the antrum and duodenum in real time, without motional image degradation, as would normally be seen using conventional MRI. Gastroduodenal flow of the luminal contents was visualised using water as a contrast medium, with appropriate adjustment of the time constant (T2) weighting of the system. Rapid (0.3 Hz) imaging of gastroduodenal motility in both transverse and coronal planes was achieved by respiratory gating to the imaging frequency, allowing repetition rates of up to 20 frames per minute for 2-3 hours. Fast replay of stored images, to produce a 'movie loop', allowed identification of fasting motility patterns of the gastric antrum and proximal small intestine, with depiction of the phases of the migrating motor complex. Images of the fed patterns after the ingestion of a test meal showed good separation of solid and liquid particulate matter and mixing waves in the gastric body. The potential for quantitative measurements with this new imaging modality of the gastrointestinal tract is under development, which will allow us to measure transit and correlate this with motility data.

Adult↗

PubMed1993

Bile reflux in columnar-lined Barrett's oesophagus.

Total and individual bile acid concentrations in the oesophageal aspirates from 30 patients with Barrett's oesophagus were compared with those from 15 patients with oesophagitis and 15 normal subjects. The highest total bile acid concentrations were found in the Barrett's patients and this was statistically significant when compared with controls but not oesophagitis patients. However, when the 95th percentile value of bile acid concentration in the normal subjects was taken as the 'cut-off' level, a significantly higher number of Barrett's patients (15/30) were bile refluxers than were the oesophagitis patients (3/15). Glycocholic and taurocholic acids were the predominant bile acids detected, but taurochenodeoxycholic acid was also present in significant amounts in the patients with oesophagitis. It is possible that bile reflux contributes to the development of Barrett's oesophagus.

Aged↗

PubMed1991

A prospective evaluation of the effect of tumor cell DNA content on recurrence in colorectal cancer.

Tumor cell DNA (ploidy) content was measured prospectively in samples from 320 patients resected for colorectal cancer with a minimum follow-up time of 2 years. All patients were followed and those with recurrence were investigated carefully. There was no correlation between tumors with an abnormal cellular DNA content (aneuploid or tetraploid) and patient age, sex, tumor site, pathologic stage, or histologic grade. In 236 patients who underwent potentially curative operations, 75 (32%) had local and/or distant recurrence. The recurrence rate was significantly higher (test statistic, 4.3; P = 0.04) for those patients with aneuploid tumors (52 of 142, 37%) compared with those with diploid tumors (23 of 94, 24%). The subgroups of patients where ploidy exerted an effect were in patients with Stage B tumors or mobile tumors and in patients over 65 years of age. Further analysis showed that there was a twofold increase in local recurrence and a threefold increase in distant recurrence in patients with aneuploid tumors, but no excess of patients who had both local and distant recurrence. Measurement of DNA ploidy can identify a group of patients undergoing curative surgery for colorectal cancer at high risk for recurrence. In combination with clinicopathologic factors, DNA ploidy may be useful in analyzing the results of trials and in planning adjuvant therapy.

Aged↗

PubMed1991

Esophageal pH monitoring for gastroesophageal reflux: a United Kingdom study.

Esophageal pH monitoring is the accepted standard for the investigation of gastroesophageal reflux (GER) in adults. A postal questionnaire was sent to 912 United Kingdom paediatric physicians & surgeons. Five hundred forty-seven (61%) replied, with 124 (22.7%) currently using the technique, mostly in conjunction with barium swallow and/or esophagoscopy. The use of pH monitoring to quantify GER was also accepted in principal as being the best determinant of reflux by a further 186 (34%), but as yet was unavailable in their hospitals. Pediatricians were also questioned as to their management of children with GER. The majority were treated medically with a variety of antireflux medication, with only 237 (42%) referring cases for surgery.

Child↗