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Diarrhea is common in infants (children less than 2 years of age), usually acute, and, if chronic, commonly caused by allergies and occasionally by infectious agents. Congenital diarrheas and enteropathies (CODEs) are rare causes of devastating chronic diarrhea in infants. Evaluation of CODEs is a lengthy process and infrequently leads to a clear diagnosis. However, genomic analyses and the development of model systems have increased our understanding of CODE pathogenesis. With these advances, a new diagnostic approach is needed. We propose a revised approach to determine causes of diarrhea in infants, including CODEs, based on stool analysis, histologic features, responses to dietary modifications, and genetic tests. After exclusion of common causes of diarrhea in infants, the evaluation proceeds through analyses of stool characteristics (watery, fatty, or bloody) and histologic features, such as the villus to crypt ratio in intestinal biopsies. Infants with CODEs resulting from defects in digestion, absorption, transport of nutrients and electrolytes, or enteroendocrine cell development or function have normal villi to crypt ratios; defects in enterocyte structure or immune-mediated conditions result in an abnormal villus to crypt ratios and morphology. Whole-exome and genome sequencing in the early stages of evaluation can reduce the time required for a definitive diagnosis of CODEs, or lead to identification of new variants associated with these enteropathies. The functional effects of gene mutations can be analyzed in model systems such as enteroids or induced pluripotent stem cells and are facilitated by recent advances in gene editing procedures. Characterization and investigation of new CODE disorders will improve management of patients and advance our understanding of epithelial cells and other cells in the intestinal mucosa., (Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Obesity usually is associated with morbidity related to diabetes mellitus and cardiovascular diseases. However, there are many gastrointestinal and hepatic diseases for which obesity is the direct cause (eg, nonalcoholic fatty liver disease) or is a significant risk factor, such as reflux esophagitis and gallstones. When obesity is a risk factor, it may interact with other mechanisms and result in earlier presentation or complicated diseases. There are increased odds ratios or relative risks of several gastrointestinal complications of obesity: gastroesophageal reflux disease, erosive esophagitis, Barrett's esophagus, esophageal adenocarcinoma, erosive gastritis, gastric cancer, diarrhea, colonic diverticular disease, polyps, cancer, liver disease including nonalcoholic fatty liver disease, cirrhosis, hepatocellular carcinoma, gallstones, acute pancreatitis, and pancreatic cancer. Gastroenterologists are uniquely poised to participate in the multidisciplinary management of obesity as physicians caring for people with obesity-related diseases, in addition to their expertise in nutrition and endoscopic interventions., (Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.)

The Phosphatase And Tensin Homolog Deleted On Chromosome 10 (PTEN) regulates the phosphoinositol-3-kinase (PI3K)-AKT signaling pathway. In a series of 34 patients with PTEN mutations, we described gastrointestinal lymphoid hyperplasia, extensive hyperplastic tonsils, thymus hyperplasia, autoimmune lymphocytic thyroiditis, autoimmune hemolytic anemia, and colitis. Functional analysis of the gastrointestinal mucosa-associated lymphoid tissue revealed increased signaling via the PI3K-AKT pathway, including phosphorylation of S6 and increased cell proliferation, but also reduced apoptosis of CD20(+)CD10(+) B cells. Reduced activity of PTEN therefore affects homeostasis of human germinal center B cells by increasing PI3K-AKT signaling via mammalian target of rapamycin as well as antiapoptotic signals., (Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Mice deficient of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) exhibit severe intestinal lesions, particularly mucous overproduction/secretion and accumulation, which is similar to meconium ileus in CF patients. Moreover, severity of the intestinal disease in CF mice is strongly influenced by genetic modifiers, and CFTR deficiency affects the expression of multiple secondary genes that may impact on the phenotype. The murine orthologue of human hCLCA1 (mCLCA3) is expressed by goblet cells and implicated in their normal function, particularly with mucus production/secretion that is exaggerated in CF; however, its influence on the CF intestinal disease, although suggested, remains unclear., Methods: To investigate the role of mCLCA3 on the CF intestinal disease in mice, its expression in this tissue has been assessed, and a CF mouse line maintaining elevated mCLCA3 levels has been developed and comprehensively characterized., Results: Expression of mCLCA3 is significantly reduced in CF mouse intestines, although the number of goblet cells is elevated, indicating marked reduction per cell. Importantly, correction of this deficiency results in amelioration of the mucous-based disease leading to a marked improvement of intestinal pathology and survival, although goblet cell hyperplasia and hypertrophy were augmented. This intestinal amelioration did not appear to be related to rectification of the CF electrophysiologic defect., Conclusions: mCLCA3 has a role in intestinal goblet cell function that includes modification of the mucous properties and/or secretion that are altered in CF. Thus, elevation of mCLCA3 (hCLCA1) levels could provide a means to reduce intestinal mucous-based lesions in CF and related diseases.

Background & Aims: The short bowel syndrome (SBS) may be associated with either transient or permanent intestinal failure, presently treated by parenteral nutrition (PN). Survival and PN-dependence probabilities, taking into account both small bowel remnant length and the type of the digestive circuit of anastomosis, are not known in adult SBS patients. The aim of this study was to assess such prognostic factors., Methods: A total of 124 consecutive adults with nonmalignant SBS were enrolled from 1980 to 1992 at 2 home PN centers. They were analyzed for survival and PN-dependence probabilities using the Cox model and for PN dependence using linear discriminant analysis. Data were updated in April 1996., Results: Survival and PN-dependence probabilities were 86% and 49% and 75% and 45% at 2 and 5 years, respectively. In multivariate analysis, survival was related negatively to end-enterostomy, to small bowel length of <50 cm, and to arterial infarction as a cause of SBS, but not to PN dependence. The latter was related negatively to postduodenal small bowel lengths of <50 and 50-99 cm and to absence of terminal ileum and/or colon in continuity. Cutoff values of small bowel lengths separating transient and permanent intestinal failure were 100, 65, and 30 cm in end-enterostomy, jejunocolic, and jejunoileocolic type of anastomosis, respectively., Conclusions: In adult SBS patients, small bowel length of <100 cm is highly predictive of permanent intestinal failure. Presence of terminal ileum and/or colon in continuity enhances both weaning off PN and survival probabilities. After 2 years of PN, probability of permanent intestinal failure is 94%. These rates may lead to selection of other treatments, especially intestinal transplantation, instead of PN, for permanent intestinal failure caused by SBS.

Background & Aims: Bowel ischemia and perforation is an infrequent but ominous event in patients with malignant lymphoma. The underlying pathogenesis of this association remains to be clarified in most cases. Seven unusual cases of angiocentric T-cell lymphoma of the intestine presenting with bowel ischemia or perforation are reported. Their clinicopathologic features were analyzed., Methods: Clinical records and histopathology were reviewed. Immunophenotypic studies and EBER1 in situ hybridization for Epstein-Barr virus were performed., Results: All patients (3 men and 4 women; mean age, 42 years) presented with acute abdominal pain, bloody stool, or bowel perforation. The intestinal lesions were ulcerated and transmurally necrotic or gangrenous. The angiodestruction of the tumor cells appeared to be responsible for the presenting bowel ischemia. The neoplastic cells expressed a pan-T-cell antigen CD45RO; 4 of them contained Epstein-Barr virus transcripts EBER1. The prognosis was grave; 6 patients died within 3 months of onset., Conclusions: Intestinal angiocentric T-cell lymphoma represents a distinct etiology of bowel ischemia. The condition should be taken into consideration, particularly in young adults with ischemic bowel disease.

In 10-day-old suckling and adult mice, reovirus type 1 adheres selectively to and penetrates membranous epithelial (M) cells. To determine when M cells first appear, when they first transport reovirus, and if reovirus adheres to and is endocytosed by other epithelial cells in the first postnatal week, we examined neonatal mouse intestine by transmission electron microscopy after reovirus type 1 exposure. At 2 days M cells accounted for 0.9% of dome epithelial cells. By 9 days M cells had increased to 7.4%. Reovirus type 1 adherence to the surface of villus and dome epithelial cells showed marked variation in 2-6-day-old animals, but by 7 days only a few absorptive cell profiles had adherent reovirus. Adherence to greater than 50% of M-cell profiles occurred in all but 2 animals, but adherence to the majority of Peyer's patch absorptive cell profiles was present only in some 4- and 5-day-old animals. Adherence to a majority of undifferentiated cell profiles occurred in some animals at all ages. Membranous epithelial cells endocytosed reovirus at all ages but only at 2 days did rare villus and dome absorptive cells endocytose reovirus into the apical cytoplasm. Thus, adherence of reovirus to the apical surface of mucosal epithelial cells is nonselective in newborn mice but becomes more selective within the first postnatal week with adherence by day 7 to most M-cell profiles, to a substantial but variable number of undifferentiated cell profiles, but to few absorptive cell profiles.

Normal and immunodeficient CBA and A2G strain mice were inoculated with crude (100 to 20 to 30 micrometer), cell-free (0.2 micrometer) filtrates of Crohn's or noninflammatory bowel disease tissue homogenates, which were either fresh or frozen to -70 degree C. Mice of each strain developed epithelioid and giant cell granulomas both locally at the site of injection and systemically in response to crude and cell-free filtrates of Crohn's tissues. Control mice did not develop such changes. The granulomas evolved slowly, predominantly between 9 and 27 months. The granuloma-inciting agent has been shown to be present in ileum, colon, and mesenteric lymph nodes of patients with Crohn's disease and it withstands freezing to -70 degree C. The use of Crohn's tissues common to this study and one in rabbits previously reported, suggests that the induction of granulomas by this agent is not strain- or species-specific, and is independent of the immune status of CBA mice.

Two patients undergoing hemodialysis for 19 and 13 yr, respectively, developed intestinal infarction with extensive amyloid deposits in the muscle layer and blood vessels. In 1 patient the deposit reacted positively with antiserum to beta 2-microglobulin by immunohistochemical stain, and therefore was classified as beta 2-microglobulin in origin. The amyloid protein of the other patient remains unclassified. In patients with gastrointestinal symptoms who have been undergoing hemodialysis for long periods of time, amyloidosis of the intestine should be considered.

A controlled, retrospective study was undertaken to ascertain whether or not abdominal surgery at any time before radiation therapy might result in an increased incidence of radiation enteropathy. One hundred and five patients in three groups were studied; 24 had radiation enteropathy which developed an average of 12.5 months after radiation therapy, and 28 were matched controls without this complication. The records of a further group of 53 unmatched controls, who survived more than 2 years after irradiation were also examined. In the group with radiation enteropathy, 18 (75%) had a history of prior surgery, whereas only 3 (10.7%) of the matched controls had been operated before irradiation (chi2 = 3.52, P less than .005). The incidence of prior surgery in the unmatched control group was 13.2%. These data indicate that abdominal surgery before radiotherapy does increase the risk of subsequent development of radiation enteropathy.

In 6 (10 to 12 kg) mongrel female dogs, silver electrodes for recording electrical activity and for pacing of pacesetter potentials (PP) were implanted on the stomach and duodenum and a catheter for intraluminal instillations was inserted into the duodenum. Beginning 2 weeks after operation, electrical recordings were made intermittently from the fasted, conscious dogs with no pacing and during pacing of the PP in the proximal and in the distal duodenum. A suspension of BaSO4 injected into the unpaced duodenum and observed cinefluoroscopically was swept quickly from the duodenum into the jejunum; little or none passed orad into the proximal duodenum, and BaSO4 rarely entered the stomach. Only 1 to 3% of a duodenal infusate of 154 mM NaCl with [14C] polyethylene glycol (2 ml per min) appeared in the stomach after 15 min. The results during proximal duodenal pacing were the same as with no pacing. However, distal duodenal pacing, which reversed the direction of propagation of the duodenal PP's, caused duodenal-gastric reflux of BaSO4 in every dog and forced about 30% of the duodenal infusate into the stomach during fasting and during gastric emptying of 400 ml of 154 mM NaCl; at the same time, the rate of emptying of the gastric instillate was slowed about 25%.