Update on management and treatment of short gut

Epithelial PIK3R1 (p85) and TP53 Regulate Survivin Expression during Adaptation to Ileocecal Resection

Intestinal adaptation to small-bowel resection (SBR) after necrotizing enterocolitis expands absorptive surface areas and promotes enteral autonomy. Survivin increases proliferation and blunts apoptosis. The current study examines survivin in intestinal epithelial cells after ileocecal resection. Wild-type and epithelial Pik3r1 (p85α)-deficient mice underwent sham surgery or 30% resection. RNA and protein were isolated from small bowel to determine levels of β-catenin target gene expression, activated caspase-3, survivin, p85α, and Trp53. Healthy and post-resection human infant small-bowel sections were analyzed for survivin, Ki-67, and TP53 by immunohistochemistry. Five days after ileocecal resection, epithelial levels of survivin increased relative to sham-operated on mice, which correlated with reduced cleaved caspase-3, p85α, and Trp53. At baseline, p85α-deficient intestinal epithelial cells had less Trp53 and more survivin, and relative responses to resection were blunted compared with wild-type. In infant small bowel, survivin in transit amplifying cells increased 71% after SBR. Resection increased proliferation and decreased numbers of TP53-positive epithelial cells. Data suggest that ileocecal resection reduces p85α, which lowers TP53 activation and releases survivin promoter repression. The subsequent increase in survivin among transit amplifying cells promotes epithelial cell proliferation and lengthens crypts. These findings suggest that SBR reduces p85α and TP53, which increases survivin and intestinal epithelial cell expansion during therapeutic adaptation in patients with short bowel syndrome.

Factors affecting survival to intestinal transplantation in the very young pediatric patient

BACKGROUND

Very young pediatric patients awaiting intestinal transplantation have a high mortality rate due to long waiting times, scarcity of appropriate size donor organs, and mortality due to sepsis and liver failure. To investigate specific risk factors impacting survival to intestinal transplantation, we performed a 4-year institutional retrospective study comparing children who received grafts by age 18 months with children 18 months or younger who died while on the waiting list.

PATIENTS AND METHODS

Twelve children comprised the transplanted group and had the underlying diagnoses: necrotizing enterocolitis, gastroschisis, Hirschsprung's disease, and omphalocele. Ten children comprised the deceased group and had the underlying diagnoses: intestinal atresia, necrotizing enterocolitis, gastroschisis, and midgut volvulus. Multiple risk factors were assessed in these groups.

RESULTS

No differences in residual small bowel length, presence of the colon, number of line infections, or number of central lines were found. The average body weight of the transplanted group trended higher, whereas the deceased group had more impairment of hepatic function. Intestinal atresia was the most common diagnosis in the deceased group while none of the transplanted group carried this diagnosis. Ileocecal valve was retained in 80% of the deceased group and in none of the transplanted group.

CONCLUSIONS

In children younger than 18 months, risk factors affecting survival to intestinal transplantation include small body size and advanced liver disease. A primary diagnosis of intestinal atresia and the presence of the ileocecal valve may confer additional risk to these very young children.

Surgical therapy for short bowel syndrome

Patients with short bowel syndrome (SBS) suffer tremendous morbidity secondary to prolonged hospitalization and chronic parenteral nutrition (TPN). Overall, the majority of infants will adapt and ultimately become independent of TPN, but this process may require many months or years. Reasons for continued TPN dependency include bowel dysmotility, bacterial overgrowth, insufficient adaptation, or very short bowel length. It is this subpopulation of patients who may benefit from surgical procedures that optimize intestinal adaptation and increase the mucosal absorptive surface area. The goal of this review article is to summarize the process of intestinal adaptation and then to outline the surgical principles and techniques available to surgeons who treat this complicated group of patients.

Neonatal congenital microvillus atrophy

Congenital microvillous atrophy (CMVA) is the leading cause of neonatal secretory diarrhoea with onset either in the first 72 hours of life (early onset) or at 6-8 weeks after birth (late onset). To date over 30 cases have been reported worldwide. The prognosis for this life threatening condition continues to be poor. Therapeutic agents like somatostatin and epidermal growth factor are either ineffective or of marginal benefit. Overall five year survival after small bowel transplantation is currently approximately 50%. The following brief review is aimed towards helping neonatologists/perinatologists in the early diagnosis, and management of CMVA and in counselling the parents appropriately.