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Biomedical subjects

M Anvari

Publications and source records attributed to M Anvari.

13 recordsLinked to original sources
PubMed1996

Does the colon adopt small bowel features in a small bowel environment?

BACKGROUND: Isoperistaltic colon interposition is one of several surgical options available in the treatment of short bowel syndrome. It functions primarily by slowing the rapid intestinal transit that follows small bowel resection (SBR). Previous studies have interposed distal colonic segments and although there is evidence of adaptation by the interposed colon it is not known whether these segments develop histologic or functional small bowel characteristics. METHODS: In this study evidence was sought of metaplasia in the interposed segments after 80% SBR and, because proximal colon is a midgut derivative, the differences between proximal and distal colonic segments were examined. RESULTS: There was no qualitative histological evidence of metaplasia by the interposed segments. There was a significant increase in crypt depth, mucosal thickness and maltase concentration of the interposed segments compared with the nontransposed colon of the controls. The maltase concentations were increased to the extent that they were not significantly different from the concentration present in normal ileum. CONCLUSIONS: Although there was no gross evidence of small bowel intestinalization by the interposed segments, there was evidence of adaptation which was not merely an extension of the adaptive process seen after SBR alone. These changes resulted in the colon taking on some small bowel features. There was no significant difference between proximal vs distal interposed segments.

Adaptation, Physiological↗
PubMed1995

Mechanics of pulsatile transpyloric flow in the pig.

1. In eight conscious pigs equipped with gastric and duodenal cannulae, the relationship of transpyloric flow to gastro-duodenal motor events was evaluated during gastric emptying of 1000 ml of saline. Rates of liquid gastric emptying were correlated with pressures at the antrum, pylorus and duodenum, recorded by a sleeve sensor and multiple perfused side-holes. Transpyloric flow was recorded concurrently by continuous collection and weighing of the duodenal effluent. 2. In three pigs the above measurements were repeated during concurrent videofluoroscopy of gastric emptying after adding 100 ml of liquid barium to the gastric instillate. 3. The mean volume of saline emptied in 30 min was 627 +/- 51.2 ml. Pulsatile flow accounted for 71% of total emptying. Pulses had a mean flow rate of 3.9 +/- 0.44 ml s-1. Most flow pulses (59%) occurred during the first 5 min of emptying. 4. Distinctive, low-amplitude (4.8 +/- 0.33 mmHg), relatively long-lasting (15.8 +/- 0.46 s) antral pressure waves were associated with 58% of flow pulses. In all antral pressure recording points, the first and longest duration component of these pressure waves had an identical timing, amplitude and waveform consistent with pressurization of the entire antrum-gastric cavity. 5. Videofluoroscopy and concurrent manometry showed that these antral common cavity pressure waves were associated with non-lumen-occlusive contractions of the gastric wall, initially observed at the corpus which propagated down to the pylorus; 93% of these contractions became lumen occlusive in the terminal antrum and pylorus when pressure waves of a unique pattern for each recording point were recorded at this level. 6. The onset of 68% of the flow pulses which accounted for 62% of pulsatile emptying occurred in the interval (mean 7.9 +/- 0.65 s) between the onset of the common cavity wave and the onset of localized, lumen-occlusive distal antral-pyloric pressure waves. 7. These findings indicate that in the pig, pulsatile emptying of non-nutrient liquids into the duodenum occurs predominantly during the non-lumen-occlusive stage of a propagated gastric contraction, which is recognisable as a common cavity pressure wave. This is a previously inadequately recognized pattern of gastric pumping.

Animals↗
PubMed1995

Role of antral intramural neural pathways in control of gastric emptying in the pig.

1. The role of antral intramural pathways in the control of antropyloric motility and gastric emptying was evaluated in five conscious pigs equipped with chronic gastric and duodenal cannulae. Neural pathways were divided by transection and re-anastomosis of the antrum 2 cm proximal to the pylorus. Concurrent measurements of gastric emptying, transpyloric flow and antropyloric motility were performed before and 6 weeks after surgery. 2. Antral transection retarded gastric emptying, only 36% of 1000 ml saline being emptied in 30 min compared with 62% before transection. Transection did not alter the number of transpyloric flow pulses (22.0 +/- 4.0 cf. 24.4 +/- 3.2 pre-transection), but reduced (P < 0.01) the volume of flow pulses substantially (8.6 +/- 0.4 cf. 18.7 +/- 1.5 ml pre-transection). 3. Antral transection was associated with a reduction in the rate of distal antral pressure waves (P < 0.05), but no alteration in the rate of phasic low level pressurization of the entire gastric content by gastric contractions (gastric common cavity pressure waves). However, transection was associated with a significant (P < 0.05) shortening of the interval between the onset of gastric common cavity pressure waves, and the onset of lumen-occlusive pyloric pressure waves generated by the same contraction sequence (3.2 +/- 0.3 cf. 7.9 +/- 0.6 s). 4. Transection did not alter the inhibition of antral pressure waves, stimulation of localized pyloric pressure waves, and retardation of gastric emptying produced by infusion of 25% dextrose into the duodenum. 5. These studies suggest that antral intramural nerves regulate the emptying of liquids from the stomach by modulating the timing of pyloric closure in relation to phasic gastric antral and corpus contractions. 6. Distal antral intramural neural pathways do not appear to play a major role in the suppression of antral motor activity produced by duodenal glucoreceptors.

Animals↗
PubMed1995

Laparoscopic Nissen fundoplication is a satisfactory alternative to long-term omeprazole therapy.

A total of 168 patients with proven gastro-oesophageal reflux disease (GORD) receiving long-term medical therapy underwent laparoscopic Nissen fundoplication. The operation was converted to open fundoplication in four patients. All patients reported complete (92.3 per cent) or partial (7.7 per cent) relief of reflux symptoms 1 month after surgery. There were no associated deaths and the perioperative complication rate was 8.9 per cent. The mean(s.e.m.) length of operating time was 69.9(2.4) min and mean(s.e.m.) hospital stay 2.7(0.1) days. Symptom score assessment, 24-h oesophageal pH recording and lower oesophageal sphincter pressure showed significant (P < 0.0001) improvement 6 months after surgery in 85 evaluable patients. Before operation 37.5 per cent of the patients were considered symptomatically controlled on omeprazole and had excellent symptom control after surgery. This initial experience suggests that laparoscopic Nissen fundoplication is a safe and effective treatment for patients with GORD requiring long-term medication.

Adolescent↗
PubMed1995

Effects of posture on gastric emptying of nonnutrient liquids and antropyloroduodenal motility.

The effects of posture on gastric emptying, intragastric distribution, and antropyloroduodenal motility after ingestion of a nonnutrient liquid have been evaluated. In seven healthy volunteers antropyloroduodenal pressures were measured for 30 min after ingestion of 150 ml of normal saline in two different positions: sitting and left lateral. Saline drinks were radiolabeled and ingested both before and after intravenous atropine (4 micrograms/kg). Rates of emptying from both the total (P < 0.05) and the proximal (P < 0.05) stomach were faster in the sitting position than in the left lateral position. There were more long (> 6 cm) antropyloric pressure waves (P < 0.05) and isolated pyloric pressure waves (P < 0.05) in the sitting position. Intravenous atropine slowed emptying in both positions (P < 0.05) and in the sitting position decreased (P < 0.05) the number of antropyloric pressure waves. After atropine, gastric emptying was also faster in the sitting compared with the decubitus position (P < 0.05), although there was no difference in antropyloric or isolated pyloric pressure waves between the two postures. We conclude that the effects of gravity on gastric emptying of nonnutrient liquids are likely to reflect changes in both antropyloric motility and intragastric distribution.

Adolescent↗
PubMed1994

Laparoscopic-assisted vagotomy and distal gastrectomy.

This is a report of the techniques used on and outcome for three patients who underwent laparoscopic-assisted vagotomy and distal gastrectomy for complicated peptic ulcer disease. The first patient had a Billroth I anastomosis in 2 h 42 min with an estimated blood loss of 200 ml. Oral fluids were started on day 3 and the diet progressed to a soft food by day 5. The patient was discharged 11 days after his gastrectomy following a transurethal prostatic resection on day 6. The second patient had a Billroth II anastomosis. The operation was completed in 4 h 40 min with an estimated blood loss of 350 ml. Oral fluids were commenced on the 1st postoperative day and the patient was tolerating a soft diet by day 4. The patient was discharged 5 days after his gastrectomy. The third patient had a Billroth I anastomosis with an estimated blood loss of less than 150 ml. The surgery took 2 h 35 min; the patient was tolerating oral fluids on the first postoperative day and was discharged on the 4th postoperative day on soft diet. Laparoscopic-assisted vagotomy and gastrectomy has the advantages of a minimal-access procedure without the risks of an intracorporeal anastomosis.

Aged↗
PubMed1994

Modulation of pumping function of gastric body and antropyloric contractions.

Gastric and antropyloric phasic contractions control transpyloric pulsatile flow, the major mechanism of gastric emptying. Both the occurrence and patterning of phasic gastric contractions are highly modulated by intestinal feedback mechanisms, with resultant variation in gastric emptying. The observed patterns of these contractions can only be plausibly explained by the action of neural influences on gastric motility. These influences derive from several mechanisms driven by intestinal feedback, central nervous system controls, and higher centers, with transmission of signals via intrinsic enteric pathways and extrinsic nerves. It is suggested that the occurrence and patterning of gastric phasic contractions depend on the spatial specificity and local modulation of the intensity of neural stimulation of gastric muscle. The resultant strength of contraction determines the occurrence and timing of lumen occlusion relative to adjacent regions. The timing of lumen occlusion in adjacent regions may be the major determinant of mechanical outcome.

Animals↗
PubMed1994

Laparoscopic Nissen fundoplication.

OBJECTIVE: The authors laparoscopic approach for a Nissen fundoplication is presented. SUMMARY BACKGROUND DATA: The technique has been undertaken in 155 patients over 29 months, with 137 patients having been observed for more than 3 months. METHODS: Three hundred sixty degree fundoplication was undertaken using three or four sutures to secure the wrap. Short gastric vessels were not divided, and the anterior wall of the stomach was used to construct the wrap around the esophagus with a large bougie in position. RESULTS: The operation was not completed laparoscopically in 19 patients because a satisfactory wrap could not be achieved. Ten patients undergoing laparoscopic fundoplication underwent a subsequent operation related to the laparoscopic procedure within 6 months, and there was one postoperative death. Seven other patients were readmitted to the hospital several days subsequent to their discharge, four because of pulmonary emboli. Of 137 patients who have been observed for more than 3 months, 133 patients are well and currently are free from reflux symptoms. CONCLUSIONS: In uncomplicated cases, laparoscopic fundoplication has similar advantages to laparoscopic cholecystectomy. In spite of the fact that it has not yet achieved the overall usefulness of open fundoplication, it seems likely that laparoscopic fundoplication will be used increasingly in the treatment of patients with gastroesophageal reflux disease.

Adult↗
PubMed1992

Relation of pyloric motility to pyloric opening and closure in healthy subjects.

The relation between pyloric motor activity, opening, and closure was examined in eight healthy men. Manometry was performed with an assembly combining 13 side holes and a sleeve sensor positioned astride the pylorus. Simultaneous with manometry, pyloric opening and closure and antroduodenal contractions were observed fluoroscopically with the antrum filled with barium. During intraduodenal normal saline infusion, coordinated antral pressure waves swept over the pylorus and ejected barium into the duodenum. No localised pyloric motor pattern was observed under these conditions. In contrast, the intraduodenal triglyceride infusion was associated with the absence of antral pressure waves and virtual absence of antral wall movement. At the pylorus, there was a zone of luminal occlusion less than 1 cm long that persisted for the period of observation. This zone of luminal occlusion corresponded precisely with manometric recordings of a narrow zone of pyloric phasic and tonic activity. During the duodenal triglyceride infusion, the pylorus was closed for 98.5% of the measurement period when basal pyloric pressure was 4 mm Hg or more, and during this motor pattern, barium did not traverse the pylorus. Localised pyloric contractions cause sustained pyloric closure, whether these contractions are phasic or tonic. These contractions occur independently of antral or duodenal contractions and may interrupt gastric emptying.

Adult↗
PubMed1992

Nervous control of distension-induced relaxation of the porcine lower oesophageal sphincter.

The mechanisms involved in the relaxation of the lower oesophageal sphincter induced by distension of the oesophagus and different parts of the stomach, were studied in an anaesthetized porcine model. A computer technique was developed allowing on-line digitizing of lower oesophageal sphincter (sleeve device) and intragastric pressures. Basal sphincter tone was slightly reduced by truncal vagotomy, an effect which seemed to be reversed by sectioning of the vagosympathetic trunks in the neck. Balloon distension of the body of the oesophagus, relaxed the sphincter irrespective of the denervation procedures carried out. Distension of the whole stomach with increasing amounts of air induced a dose-dependent relaxatory lower oesophageal sphincter response, which was also closely associated with the subsequent increases in intragastric pressure. Denervation procedures did not alter this dose-response relationship. The importance of intramural mechanisms was illustrated by the abolition of distension-induced effects in most animals studied after transection of the gastro-oesophageal junction distal to the sphincter. Balloon distension of the antrum elicited a smaller but significant sphincter relaxation, but the mechanisms behind this response seemed to be more complex than after insufflation of air.

Animals↗
PubMed1989

The effect of glucagon on esophageal peristalsis and clearance.

The effect of 0.5 mg intravenous glucagon on esophageal peristalsis and transit of water and barium was studied in nine healthy subjects by concurrent videofluoroscopy and manometry. Glucagon lowered manometric peristaltic amplitude in both mid- and distal esophagus. This reached significance (p = 0.0075) in the distal 3 cm of the esophagus 2 min after the injection. The efficiency of esophageal stripping was also reduced (increased proximal escape on fluoroscopy), and became significant (p = 0.05) at 2 min after the injection of glucagon.

Adolescent↗