Mucosal surface area of a reversed intestinal segment in rats

Restoring gut physiology in short bowel patients: from bench to clinical application of autologous intestinal reconstructive procedures

Introduction: Short bowel syndrome represents the leading etiology that causes intestinal failure both in children and adults. Total parenteral nutrition support has dramatically improved the prognosis for these patients but, if related irreversible complications occur, the alternative is represented by surgery and/or transplantation. Areas covered: Autologous gastrointestinal reconstructive procedures are a feasible, alternative approach with good long-term outcome data inexperienced surgical centers. Expert opinion: Ongoing innovative efforts have driven the surgical options for successful autologous reconstructive surgery: bowel elongation/tapering techniques (LILT, STEP, and the new SILT) together with the 'reversed bowel segment' procedure are now recognized procedures and all must be tailored to the individual patient needs to obtain the optimal result in terms of enteral autonomy. Background laboratory experimentation with new procedures e.g. options for bowel dilation techniques and distraction-induced enterogenesis, may provide additional management and treatment modalities.

Segmental reversal of distal small intestine in short bowel syndrome: a study on the influence on postoperative weight and intestinal topography in piglets

PURPOSE

The objective of the present study was to investigate the effect of segmental reversal of the distal 20 cm of the small intestine in piglets with induced SBS compared to controls with SBS alone. Primary endpoint was postoperative weight change over a period of 1 month. Secondary endpoints were the influence on cell proliferation and mucosal architecture shown by histological analysis.

METHODS

Sixteen piglets underwent a 60% resection of the distal small intestine and were randomized into two groups. Group 1 short bowel syndrome alone (SBS) (n = 8) and group 2 with reversal of a distal small intestinal segment (SBS-RS) (n = 8). Body weight was measured daily and the pigs were euthanized after 1 month. Crypt depths, villus heights and muscle layers thicknesses were measured. For the evaluation of microvilli of the brush border of the epithelium and cell proliferation, immunohistochemical staining with Villin and Ki-67 was performed.

RESULTS

No statistically significant differences were observed concerning weight gain. Mean ± SD weight gain was 2.31 ± 2.85 kg for SBS-RS and 2.03 ± 1.27 kg for SBS (p = 0.8). In the proximal jejunal segment a significant increase in villus heights was found in the SBS group and increase in the thickness of the circular and longitudinal muscle layers in the SBS-RS group. In the distal ileal segment the longitudinal muscle layer thicknesses were increased in the SBS group. Otherwise, no significant changes were found.

CONCLUSION

Reversal of a 20-cm distal segment showed no effect on weight gain, but there were some significant histological changes of unknown clinical significance.

Oral antibiotics attenuate bowel segment reversal-induced systemic inflammatory response and body weight loss in massively bowel-resected rats

BACKGROUND

Using a massively bowel-resected rat model, our previous study demonstrated that small bowel segment reversal stimulates jejunal hyperplasia but may also increase the possibility of bacterial translocation and the elevation of circulating white blood cells and serum interleukin-6 that may reduce the whole-body anabolism. The aim of this study is to investigate whether oral antibiotics might attenuate the inflammatory responses and might therefore facilitate the beneficial effects of bowel segment reversal.

METHODS

Male Wistar rats (approximately 270 g) underwent a 70% small bowel resection with (REV group) or without (CON group) a 3-cm small bowel segment reversal, or underwent a sham operation (SHAM group). After surgeries, half of the animals in the REV group were given oral clindamycin plus amoxicillin (50 plus 50 mg/kg/d, ANT group) for 3 weeks.

RESULTS

Oral antibiotics administration significantly attenuated the decreases in feeding efficiency (g of body weight/100 kcal diet) and increases in the circulation of white blood cells, serum nitric oxide, and interleukin-6 (1-way ANOVA, p < .05), which are associated with bowel segment reversal. In addition, antibiotics significantly increased serum concentrations of insulin-like growth factor-I, significantly decreased the total numbers of bacteria in the intestine, and tended to reduce the extent of jejunal hyperplasia in rats with bowel segment reversal.

CONCLUSIONS

Our results suggest that oral antibiotics may be used as an adjuvant to attenuate the inflammatory responses and to enhance the anabolic responses in massively bowel-resected patients with bowel segment reversal.

SYSTEMIC AND LOCAL SECRETIONS OF CYTOKINES AND NITRIC OXIDE IN MASSIVE BOWEL RESECTED RATS WITH OR WITHOUT SMALL BOWEL SEGMENT REVERSAL

Our previous study suggested that small bowel segment reversal stimulates jejunal hyperplasia, but that the elevated serum interleukin (IL-)6 eliminates whole-body anabolism in massive bowel resected rats. The aim of this study was to investigate systemic and local secretions of cytokines and nitric oxide (NO) in relation to whole-body and tissue responses in rats that underwent massive bowel resection with small bowel segment reversal. Seventy percent small bowel resection was performed in Wistar rats with (REV) or without (CON) a 5 cm reversed small bowel segment. Sham operation (SHAM) was performed on a third group of rats. Twelve days after surgery the REV group had significantly lower weight gain and greater serum levels of NO, IL-2 and IL-6 than the CON and SHAM groups. The weights of the livers in the REV and CON groups were significantly heavier, but these groups had lower levels of protein, tumour-necrosis factor-alpha, IL-2 and IL-6 than the SHAM group. The cecum weights of the REV group were significantly higher with increased protein and NO levels, but decreased IL-6 levels compared with the CON and SHAM groups. In the proximal small intestine the REV group had significantly increased protein levels and mucosal dry weights, but decreased interferon-gamma and IL-2 compared with the CON and SHAM groups. Our results suggested that cytokines and NO may have endocrine and paracrine/autocrine actions in regulating whole-body and tissue responses.

Small bowel segment reversal induces intestinal hyperplasia but reduces whole-body growth in massive bowel resected rats

BACKGROUND

Surgical reversal of a small bowel segment has been proposed as a means to improve nutritional status in individuals with extensive bowel resection. However, clinical experience remains controversial. The aim of this study was to determine the effects of bowel segment reversal on intestinal adaptation and whole-body anabolism.

METHODS

Male Wistar rats underwent a 70% small bowel resection with (REV) or without (CON) reversal of a 5-cm small bowel segment (5 cm distal to resected segment), or sham-operation (SHAM). After surgery (day 0), rats were fed with powdered diet from day 2 to day 12. Body weight, nitrogen balance, carcass compositions, and serum concentrations of albumin and insulin-like growth factor (IGF)-1 were determined to assess whole-body anabolism. The composition and architecture of the small intestine were measured to assess the intestinal growth response. Serum concentrations of tumor-necrosis factor (TNF)-alpha and interleukin (IL)-6 were measured to assess the response of postoperative cytokines.

RESULTS

Surgical reversal significantly increased the intestinal protein and DNA contents in the proximal segment compared with surgical resection. REV rats had a significantly slower rate of weight gain and lower serum levels of albumin and IGF-1, and had significantly greater levels of circulating white blood cells, blood urea nitrogen, and IL-6 compared with CON and SHAM rats. There were no significant differences in serum concentrations of TNF-alpha and carcass percentages of water, protein, and fat among groups.

CONCLUSIONS

Small bowel segment reversal stimulates jejunal hyperplasia but the surgical reversal induced-elevation in serum IL-6 may eliminate the whole-body anabolism in massive bowel-resected rats.

Experimental hypertrophy of myenteric neurones in the pig: a morphometric study

Muscular hypertrophy in the ileum of two pigs aged 6 weeks was induced using two different surgical techniques, narrowing of the gut circumference (mechanical stenosis) and segmental reversal of an ileal loop which results in a persistent antiperistalsis of that segment (functional stenosis). These pigs were sacrificed 5-6 weeks postoperatively. Cross sections through the gut wall at various distances from the operation sites revealed marked muscular hypertrophy in the pre-stenotic regions and in the reversed segment. Whole mounts from pre- and post-stenotic, as well as reversed ileal regions, were silver- impregnated. The corresponding ileal region of a third, nonoperated pig served as control. Using a computer-aided morphometric device, somal areas of five morphological neurone types were measured at various distances orally and anally from the operation sites and along the control ileum. Values between hypertrophic and nonhypertrophic zones as well as between two corresponding zones of nonoperated ileum were compared statistically. Along the control ileum, values revealed no differences in soma sizes. Within the experimentally altered material, somal areas of type VI neurones showed marked hypertrophy related to the sites of muscular hypertrophy whereas the other types remained constant throughout (II, IV in segmental reversal) or showed slightly larger somal areas within the post-stenotic, nonhypertrophied zones (I, V, IV in stenosis). Additionally, within the reversed segment, neuronal perikarya of type I, II, IV and V neurones were larger as compared to the neighbouring regions. However, this enlargement of perikarya within the reversed segment may not be correlated with muscular hypertrophy but rather with the transections of intramural axons before reversing this segment. The results suggest that morphologically distinct neurone types may play different roles within the mechanically stressed small intestine and possibly also in the coordination of normal muscular function.

Sequential intestinal lengthening procedures for refractory short bowel syndrome

Better understanding of the long-term delivery of parenteral nutrition (PN) in neonates and children has increased the survival for patients who have neonatal short bowel syndrome. Most infants with short bowel syndrome experience progressive enteral adaptation and are weaned from PN. This report describes the authors' clinical experience with nine infants and children who had refractory short bowel syndrome; single or sequential procedures were performed to lengthen the small bowel. Gut lengthening procedures used included a small bowel nipple valve constructed distally, to provide temporary partial obstruction and thereby induce dilatation and lengthening of the proximal small intestine (six patients). Bianchi's technique was used in three patients primarily and in six others after the bowel had been dilated and lengthened by the nipple valve. Kimura's gut lengthening technique was used in one patient after the small bowel had spontaneously become dilated subsequent to a Bianchi procedure. In all, 16 lengthening procedures were performed on the nine patients. Preoperatively, the nine patients tolerated less than 10% of their caloric intake enterally, with no evidence of improvement for a minimum of 6 months. Small bowel segments ranged from 6 to 92 cm originally and were increased an average of 2 1/2 times the original length. Two patients have been totally weaned from PN. For the patients whose lengthening procedure was performed more than 1 year ago, the percentage of enteral caloric intake averages 50%. One of the patients was profoundly impaired neurologically and was not resuscitated from an apneic episode. Another patient died in his sleep of unknown causes 1 year after intestinal lengthening.(ABSTRACT TRUNCATED AT 250 WORDS)