We studied whether physiological concentration of short-chain fatty acids (SCFAs) affects colonic transit and colonic motility in conscious rats. Intraluminal administration of SCFAs (100-200 mM) into the proximal colon significantly accelerated colonic transit. The stimulatory effect of SCFAs on colonic transit was abolished by perivagal capsaicin treatment, atropine, hexamethonium, and vagotomy, but not by guanethidine. The stimulatory effect of SCFAs on colonic transit was also abolished by intraluminal pretreatment with lidocaine and a 5-hydroxytryptamine (HT)(3) receptor antagonist. Intraluminal administration of SCFAs provoked contractions at the proximal colon, which migrated to the mid- and distal colon. SCFAs caused a significant increase in the luminal concentration of 5-HT of the vascularly isolated and luminally perfused rat colon ex vivo. It is suggested that the release of 5-HT from enterochromaffin cells in response to SCFAs stimulates 5-HT(3) receptors located on the vagal sensory fibers. The sensory information is transferred to the vagal efferent and stimulates the release of acetylcholine from the colonic myenteric plexus, resulting in muscle contraction.

All patients who reattend after head injury should undergo computed tomography as at least 14% of scans can be expected to yield positive results. Where this facility is not available patients with predictors for operation should be urgently referred for neurosurgical opinion. Other patients can be readmitted and need referral only if symptoms persist despite symptomatic treatment or there is neurological deterioration while under observation. These patients are a high risk group and should be treated seriously.

The authors review 45 pediatric patients with intra-abdominal tuberculosis (ATB) treated between May 1990 and April 1998. The diagnosis was confirmed histologically or by positive culture for Mycobacterium tuberculosis. Clinical presentation was with an abdominal mass (12), subacute obstruction (11), ascites (5), mass and ascites (4), peritonitis (4), and 9 unusual presentations. Mantoux tests were positive in 68% of patients tested. There were radiologic features suggestive of pulmonary TB in 29 patients (64%); abnormal abdominal radiographs were recorded in 21 (47%). Lymphadenopathy was noted on abdominal ultrasound in 23 of 30 patients (77%) and on computed tomography scan in a further 3 of 8 patients investigated. Ascitic fluid adenosine deaminase (ADA) levels were greater than 30 IU/l in 3 of 4 patients (75%), suggesting ATB. All 28 patients screened for human immunodeficiency virus were negative. A surgical procedure was performed in 39 patients. 29 (74%) had an elective diagnostic laparotomy for tissue diagnosis. One (3.4%) developed a postoperative intra-abdominal abscess. Ten (26%) presented with complications requiring surgical intervention including perforated viscus, segmental bowel resection, strictureplasty, adhesiolysis, or ileostomy. One of the latter died due to sepsis after having complications of persistent intestinal obstruction and cecal perforation. The authors recommend an aggressive approach to patients with suspected ATB in order to obtain an early definitive diagnosis, prevent complications, and reduce morbidity and mortality. They emphasize the importance of tissue diagnosis and confirmation by culture.