Nutritional effects of surgical and medical treatment for short bowel syndrome

Significance of the Extent of Intestinal Resection on the Outcome of a Short-bowel Syndrome in a Porcine Model

AIM OF THE STUDY

Insufficient data are available to determine the most suitable extent of intestinal resection required to induce short-bowel syndrome (SBS) in pigs. This study aimed to compare the three main SBS-models published.

METHODS

A 75%, 90%, or 100% mid-intestinal resection was performed in groups of n = 5 pigs each. Clinical (body weight, stool consistency) and biochemical (serum eletrolytes, citrulline, albumin, prealbumin, and transferrin) parameters were determined daily, functional (D-xylose resorption) and histological (intestinal villus length) parameters were determined after 2 weeks. A t-test and ANOVA were used for statistical analysis.

RESULTS

Only in the 100% group, we observed a persistent weight loss (13.6 ± 3.8%) and diarrhea, as well as a decrease in prealbumin-levels (41%) and transferrin levels (33%). Serum electrolytes remained stable in all groups during the observation period. Citrulline stabilized at different levels (100% group 13.9 ± 1.0 μmol/L; 90% group 18.8 ± 1.0 μmol/L; 75% group 26.3 ± 1.4 μmol/L; all p < .05). D-xylose resorption was lowest in the 100%, followed by 90% and 75% group (100% group 32.8 ± 4.9 mg/L; 90% group 50.0 ± 19.6 mg/L; 75% group 57.8 ± 8.8 mg/L; p = .393). Intestinal villus length decreased in all groups (100% group 11.0%; 90% group 14.0%; 75% group 19.1%).

CONCLUSIONS

75% intestinal resection is less suitable as an SBS model, as animals tend to recover remarkably. The 90% model is suitable for longer-term studies, as animals might survive longer due to partial compensation. Due to severe nutritional, biochemical, and physiological derangements, the 100% model can only be used for acute experiments and those immediately followed by small bowel transplantation.

Animal models of gastrointestinal and liver diseases. Animal models of infant short bowel syndrome: translational relevance and challenges

Intestinal failure (IF), due to short bowel syndrome (SBS), results from surgical resection of a major portion of the intestine, leading to reduced nutrient absorption and need for parenteral nutrition (PN). The incidence is highest in infants and relates to preterm birth, necrotizing enterocolitis, atresia, gastroschisis, volvulus, and aganglionosis. Patient outcomes have improved, but there is a need to develop new therapies for SBS and to understand intestinal adaptation after different diseases, resection types, and nutritional and pharmacological interventions. Animal studies are needed to carefully evaluate the cellular mechanisms, safety, and translational relevance of new procedures. Distal intestinal resection, without a functioning colon, results in the most severe complications and adaptation may depend on the age at resection (preterm, term, young, adult). Clinically relevant therapies have recently been suggested from studies in preterm and term PN-dependent SBS piglets, with or without a functional colon. Studies in rats and mice have specifically addressed the fundamental physiological processes underlying adaptation at the cellular level, such as regulation of mucosal proliferation, apoptosis, transport, and digestive enzyme expression, and easily allow exogenous or genetic manipulation of growth factors and their receptors (e.g., glucagon-like peptide 2, growth hormone, insulin-like growth factor 1, epidermal growth factor, keratinocyte growth factor). The greater size of rats, and especially young pigs, is an advantage for testing surgical procedures and nutritional interventions (e.g., PN, milk diets, long-/short-chain lipids, pre- and probiotics). Conversely, newborn pigs (preterm or term) and weanling rats provide better insights into the developmental aspects of treatment for SBS in infants owing to their immature intestines. The review shows that a balance among practical, economical, experimental, and ethical constraints will determine the choice of SBS model for each clinical or basic research question.

Intestinal proteomics in pig models of necrotising enterocolitis, short bowel syndrome and intrauterine growth restriction

Necrotising enterocolitis (NEC), short bowel syndrome (SBS) and intrauterine growth restriction (IUGR) are three conditions associated with intestinal dysfunction in newborn infants, particularly those born preterm. Piglet (Sus scrofa) models have recently been developed for NEC, SBS and IUGR, and tissue proteomic analyses have identified unknown pathways and new prognostic disease markers. Intestinal HSPs, iron metabolism proteins and proteins related to amino acid (e.g. arginine) and glucose metabolism are consistently affected by NEC progression and some of these proteins are also affected by SBS and IUGR. Parallel changes in some plasma and urinary proteins (e.g. haptoglobin, globulins, complement proteins, fatty acid binding proteins) may mirror the intestinal responses and pave the way to biomarker discovery. Explorative non-targeted proteomics provides ideas about the cellular pathways involved in intestinal adaptation during the critical neonatal period. Proteomics, combined with other -omic techniques, helps to get a more holistic picture of intestinal adaptation during NEC, SBS and IUGR. Explorative -omic research methods also have limitations and cannot replace, but only supplement, classical hypothesis-driven research that investigate disease mechanisms using a single or few endpoints.

Aldohexose malabsorption in preterm pigs is directly related to the severity of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) causes morbidity and mortality among preterm infants and is associated with nutrient malabsorption. Therefore, a preterm pig model that spontaneously develops NEC was used to investigate the relationship between severity of NEC lesions and galactose absorption in vivo and carrier-mediated glucose absorption by intact mid small intestine. Preterm pigs collected by caesarian section at 92% of gestation received parenteral nutrition with and without minimal enteral nutrition for 48 h before conversion to enteral nutrition with colostrum or an enteral formula. Pigs were killed when symptoms of NEC were observed or after 36-40 h of enteral nutrition. NEC lesions decreased in vivo absorption of galactose and mannitol by more than 50% and abolished carrier-mediated glucose uptake by tissues with lesions. Moreover, when NEC lesions were restricted to the colon, small intestinal tissues that seemed clinically healthy had decreased in vitro glucose absorption due to reduced uptake via the sodium-dependent glucose transporter with little or no involvement of the apical facilitative glucose carrier. The present findings reveal a direct relationship between the severity of NEC lesions and the magnitude of sugar malabsorption that is detectable before clinical symptoms are evident.

Serial transverse enteroplasty enhances intestinal function in a model of short bowel syndrome

OBJECTIVE/SUMMARY BACKGROUND DATA: Serial transverse enteroplasty (STEP) is a new intestinal lengthening procedure that has been shown to clinically increase bowel length. This study examined the impact of the STEP procedure upon intestinal function in a model of short bowel syndrome.

METHODS

Young pigs (n=10) had a reversed segment of bowel interposed to induce bowel dilatation. Five pigs underwent a 90% bowel resection with a STEP procedure on the remaining dilated bowel while 5 served as controls and had a 90% bowel resection without a STEP procedure. Determinations of nutritional status, absorptive capacity, and bacterial overgrowth were conducted 6 weeks after resection. Statistical comparisons were made by 2-sample t test (significance at P<0.05).

RESULTS

The STEP procedure lengthened the bowel from 105.2+/-7.7 cm to 152.2+/-8.3 cm (P<0.01). The STEP animals showed improved weight retention compared with controls (mean, -0.5%+/-1.8% body weight versus -17.6%+/-1.5%, P<0.001). Intestinal carbohydrate absorption, as measured by d-Xylose absorption and fat absorptive capacity as measured by serum vitamin D and triglyceride levels, were increased in the STEP group versus controls. Serum citrulline, a marker of intestinal mucosal mass, was significantly elevated in the STEP pigs compared with controls. None of the STEP animals but 4 of 5 control animals were noted to have gram-negative bacterial overgrowth in the proximal bowel.

CONCLUSIONS

STEP improves weight retention, nutritional status, intestinal absorptive capacity, and serum citrulline levels in a porcine short bowel model. A salutary effect upon bacterial overgrowth was also noted. These data support the use of this operation in short bowel syndrome.

Impaired absorption of marked oligopeptide Glycine-I Tyrosine-Glycine after successful autologous-allotopic ileal mucosa transplantation in beagles

PURPOSE

After establishing a method for ileal mucosa transplantation in an animal model, the authors investigated the absorptive capacity for oligopeptides of the transplanted mucosa.

METHODS

In 14 beagle dogs the authors transplanted ileal mucosa in a vascularized demucosed segment of the transverse colon. The colonic wall-ileal mucosa complex then was integrated in the ileal continuity. Six animals were lost owing to operative complications. Absorptive capacity for oligopeptides was measured in the remaining 8 animals with the iodine 131 (131I)-marked tripeptide glycine-tyrosine-glycine before and 4 weeks after transplantation. The results were compared and analyzed with the Student's t test for matched pairs. Blood concentrations of the marked tripeptide with P value less than .05 were considered as a significant reduction in the absorptive capacity of the transplanted ileal mucosa. After fixation with glutaraldehyd graft, uptake of the colonic wall-ileal mucosa complex was evaluated histologically in 8 animals.

RESULTS

In all 8 animals, a 100% graft uptake was verified in all sections. Fifteen minutes after application of 15 MBc Glycine-131I-Tyrosine-Glycine there was no significant difference in the absorption between normal and transplanted ileal mucosa. After 30 minutes, the absorption of the transplanted ileal mucosa showed a tendency (P < .1) for an impaired uptake of the marked tripeptide. However, 60 minutes after application the difference in the absorptive capacity of the transplanted ileal mucosa was significant (P < .05).

CONCLUSIONS

Autologous allotopic ileal mucosa transplantation is feasible; however, an impaired absorption of oligopeptides of the transplanted mucosa 4 weeks after transplantation could be observed.