Intestinal Motility and its Disorders

Colonic transit time in mentally retarded persons

INTRODUCTION

Constipation is frequently seen in patients with mental retardation (MR). Its pathophysiology is poorly understood. Measurement of colon transit time (CTT) differentiates between retentive and non-retentive constipation.

AIM

To determine total and segmental CTT in MR patients compared to healthy controls.

METHOD

Of 250 residents, 60 patients older then 16, without swallowing disorder or scoliosis, are randomly chosen, 58 participated (intelligence quotient < 50, median age 35.5 year, 29 male). Constipation was defined as less than three defecations a week. Controls are 32 non-constipated age-matched healthy volunteers (median age 29 year, 19 male). CTT is measured by daily administration of ten radio-opaque markers during 6 days and abdominal X-ray on day 7. CTT is calculated using Bouchoucha's [7] method.

RESULTS

Compared to controls, total CTT is significantly (P < 0.001) longer in MR (median 22.8 h vs. 57.6 h, respectively). Of the MR patients, 21/58 (36%) are constipated. The mental retardated and constipated (MRC) have a significant prolonged CTT in all segments (P < 0.01; median right CTT 19.2 h vs. 4.8 h; left CTT 14.4 h vs. 4.8 h; rectosigmoidal CTT 42 h vs. 9.6 h), whereas in mental retarded non-constipated (MRNC) persons, the rectosigmoidal CTT is prolonged (median 21.6 h vs. 9.6 h).

CONCLUSION

Patients with moderate to deep MR have a significantly prolonged total CTT. In MRNC persons, rectosigmoidal CTT prolongation suggests a defecation problem. In MRC, CTT is prolonged in all segments, suggesting diffuse colonic inertia problem.

Impaired gastric motility in the gastroesophageal reflux rat model: an in vitro study

PURPOSE

The present study investigated the effects of acid and mixed reflux on the responsiveness of gastric smooth muscle in the gastroesophageal reflux (GER) rat model.

MATERIAL AND METHODS

Three groups of rat were studied encompassing acid reflux, mixed reflux and sham operation. Acid reflux was induced by pyloric ligation (AR group) and mixed reflux was induced by jejunal ligation 1 cm distal to Treitz ligament (MR group). Similar surgical manipulations were carried out in the sham operated rats (SO group). Carbachol-, serotonin-, KCl-induced contractile response and nicotine-, sodium nitroprusside-, papaverine-induced relaxant response in isolated gastric fundus smooth muscle strips were determined using in vitro muscle technique 24 h after surgery.

RESULTS

Isolated gastric fundus smooth muscle contractility to serotonin, carbachol or KCl was significantly reduced in the AR and MR groups with decreased Emax and pD(2) values compared with the SO group. Relaxant responses to nicotine was significantly increased in the AR and MR groups with increased Emax and pD(2) values compared with the SO group. Sodium nitroprusside and papaverine-induced-relaxant responses were similar in all of the groups and there was no change in agonist potency.

CONCLUSION

The present study indicates that decreased contractile and increased nicotine-induced relaxant response of the gastric smooth muscle in the surgically created GER model. These findings suggest that impaired gastric smooth muscle reactivity at least in part may play a role in gastric dysmotility in GER.

Involvement of endogenous nitric oxide and c-kit-expressing cells in chronic intestinal pseudo-obstruction

BACKGROUND/PURPOSE

Chronic intestinal pseudo-obstruction (CIP) in infants and children is a motility disorder without apparent mechanical cause. Nitric oxide (NO), an inhibitory neurotransmitter and c-kit cells, essential for the intestinal pacemaker activity, both play a key role in the intestinal motility function. In the current study, the authors investigated the distributive change in the intestinal nitric oxide synthase (NOS) and c-kit cells of patients with CIP.

METHODS

Tissues were obtained from 4 patients undergoing bowel resection or biopsy for CIP at laparotomy. For controls, the intestinal specimens were obtained from 4 age-matched cases of intestinal stricture, intussusception, and autopsy with no evidence of gastrointestinal disease. Immunohistochemical studies were performed on paraffin-embedded tissue cross sections with neuronal NOS and inducible NOS monoclonal antibody as well as a rabbit polyclonal antibody against the human c-kit receptor.

RESULTS

Under immunohistochemical staining, a greatly increased density of neuronal NOS immunoreactivity and an evidently increased number of intense NOS immunoreactive nerve fibers were observed in the myenteric plexus and circular muscle layers compared with the control sections. In the submucosal plexus and longitudinal muscle layer, there was no change in NOS immunoreactivity. Inducible NOS immunoreactivity was not detected in the control cases. However, in tissues of CIP, almost all the epithelial cells were positively and strongly labeled for inducible NOS immunoreactivity. For c-kit cells staining, the number of c-kit-positive cells in the myenteric plexus and circular muscle layers were greatly less than that in the controls, especially in the myenteric plexus region.

CONCLUSION

These findings suggest that sustained production of NO by an increased NOS activity and a deficiency of c-kit cells in the intestine may be related to the pathogenesis of CIP.

Successful management of idiopathic intestinal pseudo-obstruction with cisapride

This is a case report of a previously asymptomatic 11-year-old boy who developed chronic intestinal pseudo-obstruction. Barium studies revealed grossly disordered motility of the proximal small bowel, and ganglion cells in a gastric biopsy were mildly abnormal. Treatment with conventional prokinetic agents and gastrojejunostomy were ineffective. Intravenous cisapride induced an immediate remission, which has been maintained subsequently by rectal administration of the drug.

Gastric emptying with gastro-oesophageal reflux

The time taken for gastric emptying of a liquid (milk) or a semi-liquid (pudding) meal was evaluated in 477 infants and children. These patients were referred for suspected gastro-oesophageal reflux and underwent gastro-oesophageal scintigraphy, prolonged oesophageal pH study, manometric evaluation of the lower oesophageal sphincter pressure, and fibreoptic endoscopy. No difference in gastric emptying was observed in children aged under 3 years, regardless of the presence or absence of the gastro-oesophageal reflux, the pressure of the lower oesophageal sphincter, or the presence of oesophagitis. In children over 6 years, however, gastric emptying was significantly delayed in those presenting with reflux compared with those without reflux; in children over 3 years there was slower gastric emptying in those with a decreased lower oesophageal sphincter pressure compared with those with higher pressure and in those with overt oesophagitis compared with those without oesophagitis. This study suggests that gastro-oesophageal reflux is more severe in childhood than in infancy, probably due to more complex motor disorders affecting the gastric fundus as well as lower oesophageal sphincter function.