Improving Bowel Management in Children With Spina Bifida

OBJECTIVES

In individuals with spina bifida (SB), bowel incontinence is associated with lower quality of life and lower likelihood of employment. In an effort to maximize bowel continence in children and adolescents, we created a bowel management assessment and follow-up protocol in a multidisciplinary clinic. Here we report the results of this protocol using quality-improvement methodology.

METHODS

Continence was defined as no unplanned bowel movements. Our protocol involved: (1) a standardized 4-item questionnaire about bowel continence and consistency; (2) if the patient was not achieving continence, an intervention starting with oral medication (stimulant and/or osmotic laxatives), and/or suppositories (glycerin or bisacodyl) followed by an escalation to trans-anal irrigation, or continence surgery; and (3) follow-up phone calls at regular intervals to monitor progress and make changes as needed. Results are summarized with descriptive statistics.

RESULTS

We screened 178 eligible patients in the SB clinic. Eighty-eight agreed to participate in the bowel management program. Of those who did not participate, the majority (68/90, 76%) were already achieving continence with their bowel regimen. Of children in the program, most (68/88, 77%) had a diagnosis of meningomyelocoele. At 1 year, the proportion of patients who were bowel accident free improved to 46% (vs 22% initially, P = 0.0007).

CONCLUSIONS

A standardized bowel management protocol, primarily the use of suppositories and trans-anal irrigation to achieve social continence, as well as frequent telephone follow-up, can reduce bowel incontinence in children and adolescents with SB.

Human Challenge Studies for Cholera

The human challenge model permits an estimate of the vaccine protection against moderate and severe cholera. It eliminates the difficulty in setting up a vaccine study in endemic area including uncertainties about the incidence of cholera and the logistic arrangements for capturing those who do/do not become ill. Valuable information from small groups of subjects can be obtained in a short period. Under proper precautions and study design, the challenge model is safe and efficient. Although the model has evolved since it was introduced over 50 years ago, it has been used extensively to test vaccine efficacy. Vaccine licensure has resulted from data obtained using the human challenge model. In addition, the model has been used to: (1) Establish and validate a standardized inoculum, (2) Identify immune markers and immune responses, (3) Determine natural immunity (in re-challenge studies), (4) Identify the role of the gastric acid barrier in preventing cholera infection, (5) Show homologous and heterologous infection-derived immunity, and (6) Test the efficacy of anti-diarrheal/anti-secretory small molecules. The aim of this chapter is to present an overview on the state of the art for human challenge models used to study cholera and new medical interventions against it.

Intestinal Guanylate Cyclase-C mRNA Expression in Duodenum and Colon of Children

OBJECTIVES

Guanylate cyclase-C (GC-C) agonists, which increase intestinal secretion and accelerate transit, are used to treat chronic constipation and constipation-predominant irritable bowel syndrome and are being evaluated for pediatric use. Prior studies suggest GC-C receptor density may be higher in young children, potentially amplifying GC-C agonism with treatment implications. We aimed to quantitate duodenal and colonic GC-C mRNA expression in children.

METHODS

Mucosal biopsies were obtained from subjects aged 6 months to 18 years during clinically indicated upper, that is, esophago-gastro-duodenal, and/or colonic endoscopy. Tissue samples without histologic abnormalities were grouped by subject age (<24 months, 24 months to <6 years, 6 to <12 years, and 12 to <18 years) and analyzed for GC-C mRNA expression by qPCR. The relationship between GC-C mRNA levels and age was modeled using regression analyses.

RESULTS

Ninety-nine subjects underwent upper endoscopy/colonoscopy; 93 had evaluable samples. Mean relative GC-C mRNA expression was 2.36 (range 2.21-2.46) for duodenal samples and 1.56 (range 1.22-1.91) for colonic samples. Predicted and observed normalized GC-C mRNA expression in each region were comparable among age groups. Pooled expression by region demonstrated lower expression in colonic versus duodenal samples.

CONCLUSIONS

Uniform levels of GC-C mRNA expression were detected in children aged >6 months in the duodenum and >12 months in the colon. Higher expression was observed in all age groups in duodenal versus colonic samples, indicating regional variability in GC-C receptor density. These data are reassuring for further studies of GC-C agonists in children.

Lipopolysaccharide-specific memory B cell responses to an attenuated live cholera vaccine are associated with protection against Vibrio cholerae infection

BACKGROUND

The single-dose live attenuated vaccine CVD 103-HgR protects against experimental Vibrio cholerae infection in cholera-naïve adults for at least 6 months after vaccination. While vaccine-induced vibriocidal seroconversion is associated with protection, vibriocidal titers decline rapidly from their peak 1-2 weeks after vaccination. Although vaccine-induced memory B cells (MBCs) might mediate sustained protection in individuals without detectable circulating antibodies, it is unknown whether oral cholera vaccination induces a MBC response.

METHODS

In a study that enrolled North American adults, we measured lipopolysaccharide (LPS)- and cholera toxin (CtxB)-specific MBC responses to PXVX0200 (derived from the CVD 103-HgR strain) and assessed stool volumes following experimental Vibrio cholerae infection. We then evaluated the association between vaccine-induced MBC responses and protection against cholera.

RESULTS

There was a significant increase in % CT-specific IgG, % LPS-specific IgG, and % LPS-specific IgA MBCs which persisted 180 days after vaccination as well as a significant association between vaccine-induced increase in % LPS-specific IgA MBCs and lower post-challenge stool volume (r = -0.56, p < 0.001).

DISCUSSION

Oral cholera vaccination induces antigen-specific MBC responses, and the anamnestic LPS-specific responses may contribute to long-term protection and provide correlates of the duration of vaccine-induced protection.

CLINICAL TRIALS REGISTRATION

NCT01895855.

Rotavirus immunization: Global coverage and local barriers for implementation

BACKGROUND

Rotavirus (RV) is a major agent of gastroenteritis and an important cause of child death worldwide. Immunization (RVI) has been available since 2006, and the Federation of International Societies of Gastroenterology Hepatology and Nutrition (FISPGHAN) identified RVI as a top priority for the control of diarrheal illness. A FISPGHAN working group on acute diarrhea aimed at estimating the current RVI coverage worldwide and identifying barriers to implementation at local level.

METHODS

A survey was distributed to national experts in infectious diseases and health-care authorities (March 2015-April 2016), collecting information on local recommendations, costs and perception of barriers for implementation.

RESULTS

Forty-nine of the 79 contacted countries (62% response rate) provided a complete analyzable data. RVI was recommended in 27/49 countries (55%). Although five countries have recommended RVI since 2006, a large number (16, 33%) included RVI in a National Immunization Schedule between 2012 and 2014. The costs of vaccination are covered by the government (39%), by the GAVI Alliance (10%) or public and private insurance (8%) in some countries. However, in most cases, immunization is paid by families (43%). Elevated cost of vaccine (49%) is the main barrier for implementation of RVI. High costs of vaccination (rs=-0.39, p=0.02) and coverage of expenses by families (rs=0.5, p=0.002) significantly correlate with a lower immunization rate. Limited perception of RV illness severity by the families (47%), public-health authorities (37%) or physicians (24%) and the timing of administration (16%) are further major barriers to large- scale RVI programs.

CONCLUSIONS

After 10years since its introduction, the implementation of RVI is still unacceptably low and should remain a major target for global public health. Barriers to implementation vary according to setting. Nevertheless, public health authorities should promote education for caregivers and health-care providers and interact with local health authorities in order to implement RVI.

Required and Elective Experiences During the 4th Year: An Analysis of ACGME Accredited Psychiatry Residency Program Websites

OBJECTIVE

The objective of this study was to assess and describe required and elective components of the 4th post-graduate year (PGY4) in psychiatry residency programs.

METHODS

We reviewed the websites of all 193 2014-2015 ACGME accredited psychiatry residency programs for content describing the specific components of the PGY4 year.

RESULTS

Nearly all residency programs (99 %) had some form of required experiences during the PGY4 year. Ninety-four percent had clinical requirements for PGY4 residents, with longitudinal outpatient clinic being the most common (77 %). All programs offered some elective time during PGY4, but the amount of time ranged from 2 months to 100 %.

CONCLUSION

Virtually all residency programs include some requirements in the 4th year (most commonly didactics and outpatient clinic) in addition to a broad array of elective experiences. Although 3 years may suffice for residents to complete ACGME requirements, a variety of factors may motivate programs to include required 4th year curricula. Future studies should explore the rationales for and possible benefits of programmatic requirements throughout 4 versus only 3 years of psychiatric training.

Single-dose Live Oral Cholera Vaccine CVD 103-HgR Protects Against Human Experimental Infection With Vibrio cholerae O1 El Tor

BACKGROUND

No licensed cholera vaccine is presently available in the United States. Cholera vaccines available in other countries require 2 spaced doses. A single-dose cholera vaccine that can rapidly protect short-notice travelers to high-risk areas and help control explosive outbreaks where logistics render 2-dose immunization regimens impractical would be a major advance.PXVX0200, based on live attenuated Vibrio cholerae O1 classical Inaba vaccine strain CVD 103-HgR, elicits seroconversion of vibriocidal antibodies (a correlate of protection) within 10 days of a single oral dose. We investigated the protection conferred by this vaccine in a human cholera challenge model.

METHODS

Consenting healthy adult volunteers, 18-45 years old, were randomly allocated 1:1 to receive 1 oral dose of vaccine (approximately 5 × 10(8) colony-forming units [CFU]) or placebo in double-blind fashion. Volunteers ingested approximately 1 × 10(5) CFU of wild-type V. cholerae O1 El Tor Inaba strain N16961 10 days or 3 months after vaccination and were observed on an inpatient research ward for stool output measurement and management of hydration.

RESULTS

The vaccine was well tolerated, with no difference in adverse event frequency among 95 vaccinees vs 102 placebo recipients. The primary endpoint, moderate (≥3.0 L) to severe (≥5.0 L) diarrheal purge, occurred in 39 of 66 (59.1%) placebo controls but only 2 of 35 (5.7%) vaccinees at 10 days (vaccine efficacy, 90.3%; P < .0001) and 4 of 33 (12.1%) vaccinees at 3 months (vaccine efficacy, 79.5%; P < .0001).

CONCLUSIONS

The significant vaccine efficacy documented 10 days and 3 months after 1 oral dose of PXVX0200 supports further development as a single-dose cholera vaccine.

CLINICAL TRIALS REGISTRATION

NCT01895855.

Current Issues in Transitioning from Pediatric to Adult-Based Care for Youth with Chronic Health Care Needs

For over 25 years, with medical advances increasing the lifespan of YYASHCN, we have been aware of the need to improve health care transition to adult-based care services. Barriers to health care transition have been identified and in a number of settings, recognition of the problem and preliminary success has been achieved for pilot programs. Evidence-based solutions to improve health care transition for YYASHCN are needed. There are barriers at the patient, family, pediatric, and adult provider, and insurance system levels that must be overcome.

CNS, lung, and lymph node involvement in Gaucher disease type 3 after 11 years of therapy: clinical, histopathologic, and biochemical findings

A Caucasian male with Gaucher disease type 3, treated with continuous enzyme therapy (ET) for 11 years, experienced progressive mesenteric and retroperitoneal lymphadenopathy, lung disease, and neurological involvement leading to death at an age of 12.5 years. Autopsy showed significant pathology of the brain, lymph nodes, and lungs. Liver and spleen glucosylceramide (GluCer) and glucosylsphingosine (GluS) levels were nearly normal and storage cells were cleared. Clusters of macrophages and very elevated GluCer and GluS levels were in the lungs, and brain parenchymal and perivascular regions. Compared to normal brain GluCer (GC 18:0), GluCer species with long fatty acid acyl chains were increased in the patient's brain. This profile was similar to that in the patient's lungs, suggesting that these lipids were present in brain perivascular macrophages. In the patient's brain, generalized astrogliosis, and enhanced LC3, ubiquitin, and Tau signals were identified in the regions surrounding macrophage clusters, indicating proinflammation, altered autophagy, and neurodegeneration. These findings highlight the altered phenotypes resulting from increased longevity due to ET, as well as those in poorly accessible compartments of brain and lung, which manifested progressive disease involvement despite ET.

Impact of the information age on residency training: communication, access to public information, and clinical care

Access to technology in practice helps physicians manage information, communicate, and research topics; however, those in training receive almost no formal preparation for integrating web-based technologies into practice. One reason for this is that many faculty-aside from junior faculty or those in recent generations-did not grow up using Internet communication, may use it minimally, if at all, in their own practices, and may know little about its forms and varieties. This report presents a case to illustrate how these disparities may play out in the supervisory situation and makes suggestions about helping supervisors integrate technology-awareness into their teaching.

Effect of guanylate cyclase-C activity on energy and glucose homeostasis

Uroguanylin is a gastrointestinal hormone primarily involved in fluid and electrolyte handling. It has recently been reported that prouroguanylin, secreted postprandially, is converted to uroguanylin in the brain and activates the receptor guanylate cyclase-C (GC-C) to reduce food intake and prevent obesity. We tested central nervous system administration of two GC-C agonists and found no significant reduction of food intake. We also carefully phenotyped mice lacking the GC-C receptor and found them to have normal body weight, adiposity, and glucose tolerance. Interestingly, uroguanylin knockout mice had a small but significant increase in body weight and adiposity that was accompanied by glucose intolerance. Our data indicate that the modest effects of uroguanylin on energy and glucose homeostasis are not mediated by central GC-C receptors.

Linaclotide inhibits colonic nociceptors and relieves abdominal pain via guanylate cyclase-C and extracellular cyclic guanosine 3',5'-monophosphate

BACKGROUND & AIMS

Linaclotide is a minimally absorbed agonist of guanylate cyclase-C (GUCY2C or GC-C) that reduces symptoms associated with irritable bowel syndrome with constipation (IBS-C). Little is known about the mechanism by which linaclotide reduces abdominal pain in patients with IBS-C.

METHODS

We determined the effects of linaclotide on colonic sensory afferents in healthy mice and those with chronic visceral hypersensitivity. We assessed pain transmission by measuring activation of dorsal horn neurons in the spinal cord in response to noxious colorectal distention. Levels of Gucy2c messenger RNA were measured in tissues from mice using quantitative reverse transcription polymerase chain reaction and in situ hybridization. We used human intestinal cell lines to measure release of cyclic guanosine-3',5'-monophosphate (cGMP) by linaclotide. We performed a post-hoc analysis of data from a phase III, double-blind, parallel-group study in which 805 patients with IBS-C were randomly assigned to groups given an oral placebo or 290 μg linaclotide once daily for 26 weeks. We quantified changes in IBS-C symptoms, including abdominal pain.

RESULTS

In mice, linaclotide inhibited colonic nociceptors with greater efficacy during chronic visceral hypersensitivity. Intra-colonic administration of linaclotide reduced signaling of noxious colorectal distention to the spinal cord. The colonic mucosa, but not neurons, was found to express linaclotide's target, GC-C. The downstream effector of GC-C, cGMP, was released after administration of linaclotide and also inhibited nociceptors. The effects of linaclotide were lost in Gucy2c(-/-) mice and prevented by inhibiting cGMP transporters or removing the mucosa. During 26 weeks of linaclotide administration, a significantly greater percentage of patients (70%) had at least a 30% reduction in abdominal pain compared with patients given placebo (50%).

CONCLUSIONS

We have identified an analgesic mechanism of linaclotide: it activates GC-C expressed on mucosal epithelial cells, resulting in the production and release of cGMP. This extracellular cGMP acts on and inhibits nociceptors, thereby reducing nociception. We also found that linaclotide reduces chronic abdominal pain in patients with IBS-C.

Induction of cytochrome P450-mediated detoxification of xanthotoxin in the black swallowtail

Xanthotoxin is a phototoxic allomone found in many of the host plants of the black swallowtail,Papilio polyxenes (Lepidoptera: Papilionidae). When added to the diet of final instar larvae, xanthotoxin can induce the cytochrome P450 monooxygenase (P450) activity in midgut microsomes by which it is detoxified. Induction is dose-dependent, increasing sevenfold when larvae feed on parsley treated topically with xanthotoxin at 0.5 or 1.0% fresh weight. Although xanthotoxin exerts much of its toxic effects when photoactivated by ultraviolet light, induction of P450 activity did not differ in the presence or absence of ultraviolet light. Despite a 4.7-fold induction of xanthotoxin-metabolizing P450 activity, total P450 content measured in the same microsomal samples did not increase significantly. These data indicate that multiple forms of P450 exist in the black swallowtail midgut and that they are differentially induced by xanthotoxin.

Guanylate cyclase C deficiency causes severe inflammation in a murine model of spontaneous colitis

Background

Guanylate Cyclase C (GC-C; Gucy2c) is a transmembrane receptor expressed in intestinal epithelial cells. Activation of GC-C by its secreted ligand guanylin stimulates intestinal fluid secretion. Familial mutations in GC-C cause chronic diarrheal disease or constipation and are associated with intestinal inflammation and infection. Here, we investigated the impact of GC-C activity on mucosal immune responses.

Methods

We utilized intraperitoneal injection of lipopolysaccharide to elicit a systemic cytokine challenge and then measured pro-inflammatory gene expression in colonic mucosa. GC-C^+/+ and GC-C^−/− mice were bred with interleukin (IL)-10 deficient animals and colonic inflammation were assessed. Immune cell influx and cytokine/chemokine expression was measured in the colon of wildtype, IL-10^−/−, GC-C^+/+IL-10^−/− and GC-C^−/−IL-10^−/− mice. GC-C and guanylin production were examined in the colon of these animals and in a cytokine-treated colon epithelial cell line.

Results

Relative to GC-C^+/+ animals, intraperitoneal lipopolysaccharide injection into GC-C^−/− mice increased proinflammatory gene expression in both whole colon tissue and in partially purified colonocyte isolations. Spontaneous colitis in GC-C^−/−IL-10^−/− animals was significantly more severe relative to GC-C^+/+IL-10^−/− mice. Unlike GC-C^+/+IL-10^−/− controls, colon pathology in GC-C^−/−IL-10^−/− animals was apparent at an early age and was characterized by severely altered mucosal architecture, crypt abscesses, and hyperplastic subepithelial lesions. F4/80 and myeloperoxidase positive cells as well as proinflammatory gene expression were elevated in GC-C^−/−IL-10^−/− mucosa relative to control animals. Guanylin was diminished early in colitis in vivo and tumor necrosis factor α suppressed guanylin mRNA and protein in intestinal goblet cell-like HT29-18-N2 cells.

Conclusions

The GC-C signaling pathway blunts colonic mucosal inflammation that is initiated by systemic cytokine burst or loss of mucosal immune cell immunosuppression. These data as well as the apparent intestinal inflammation in human GC-C mutant kindred underscore the importance of GC-C in regulating the response to injury and inflammation within the gut.

Guanylate cyclase C limits systemic dissemination of a murine enteric pathogen

Background

Guanylate Cyclase C (GC-C) is an apically-oriented transmembrane receptor that is expressed on epithelial cells of the intestine. Activation of GC-C by the endogenous ligands guanylin or uroguanylin elevates intracellular cGMP and is implicated in intestinal ion secretion, cell proliferation, apoptosis, intestinal barrier function, as well as the susceptibility of the intestine to inflammation. Our aim was to determine if GC-C is required for host defense during infection by the murine enteric pathogen Citrobacter rodentium of the family Enterobacteriacea.

Methods

GC-C^+/+ control mice or those having GC-C genetically ablated (GC-C^−/−) were administered C. rodentium by orogastric gavage and analyzed at multiple time points up to post-infection day 20. Commensal bacteria were characterized in uninfected GC-C^+/+ and GC-C^−/− mice using 16S rRNA PCR analysis.

Results

GC-C^−/− mice had an increase in C. rodentium bacterial load in stool relative to GC-C^+/+. C. rodentium infection strongly decreased guanylin expression in GC-C^+/+ mice and, to an even greater degree, in GC-C^−/− animals. Fluorescent tracer studies indicated that mice lacking GC-C, unlike GC-C^+/+ animals, had a substantial loss of intestinal barrier function early in the course of infection. Epithelial cell apoptosis was significantly increased in GC-C^−/− mice following 10 days of infection and this was associated with increased frequency and numbers of C. rodentium translocation out of the intestine. Infection led to significant liver histopathology in GC-C^−/− mice as well as lymphocyte infiltration and elevated cytokine and chemokine expression. Relative to naïve GC-C^+/+ mice, the commensal microflora load in uninfected GC-C^−/− mice was decreased and bacterial composition was imbalanced and included outgrowth of the Enterobacteriacea family.

Conclusions

This work demonstrates the novel finding that GC-C signaling is an essential component of host defense during murine enteric infection by reducing bacterial load and preventing systemic dissemination of attaching/effacing-lesion forming bacterial pathogens such as C. rodentium.

Recurrent pancreatitis in ornithine transcarbamylase deficiency

Ornithine transcarbamylase (OTC) deficiency is a urea cycle defect with varying frequency and severity of episodes of hyperammonemia. We report three patients with OTC deficiency with recurrent pancreatitis. The pathogenesis of acute pancreatitis in this patient population requires further elucidation. Pancreatitis significantly affected dietary/metabolic management and increased frequency of hospitalizations.

Role for the membrane receptor guanylyl cyclase-C in attention deficiency and hyperactive behavior

Midbrain dopamine neurons regulate many important behavioral processes, and their dysfunctions are associated with several human neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD) and schizophrenia. Here, we report that these neurons in mice selectively express guanylyl cyclase-C (GC-C), a membrane receptor previously thought to be expressed mainly in the intestine. GC-C activation potentiates the excitatory responses mediated by glutamate and acetylcholine receptors via the activity of guanosine 3',5'-monophosphate-dependent protein kinase (PKG). Mice in which GC-C has been knocked out exhibit hyperactivity and attention deficits. Moreover, their behavioral phenotypes are reversed by ADHD therapeutics and a PKG activator. These results indicate important behavioral and physiological functions for the GC-C/PKG signaling pathway within the brain and suggest new therapeutic targets for neuropsychiatric disorders related to the malfunctions of midbrain dopamine neurons.

Murine guanylate cyclase C regulates colonic injury and inflammation

Guanylate cyclase C (GUCY2C or GC-C) and its ligands, guanylin (GUCA2A or Gn) and uroguanylin (GUCA2B or Ugn), are expressed in intestinal epithelial cells and regulate ion secretion, intestinal barrier function, and epithelial monolayer homeostasis via cGMP-dependent signaling pathways. The aim of this study was to determine whether GC-C and its ligands direct the course of intestinal inflammation. In this article, we show that dextran sodium sulfate (DSS)-induced clinical disease and histological damage to the colonic mucosa were significantly less severe in GC-C(-/-) mice and moderately reduced in Gn(-/-) animals. Relative to wild-type controls, GC-C(-/-) and Gn(-/-) mice had reduced apoptosis and increased proliferation of intestinal epithelial cells during DSS colitis. Basal and DSS-induced production of resistin-like molecule β (RELMβ) was substantially diminished in GC-C(-/-) mice. RELMβ is thought to stimulate cytokine production in macrophages in this disease model and, consistent with this, TNF-α and IFN-γ production was minimal in GC-C(-/-) animals. RELMβ and cytokine levels were similar to wild-type in Gn(-/-) mice, however. Colonic instillation of recombinant RELMβ by enema into GC-C(-/-) mice restores sensitivity to DSS-mediated mucosal injury. These findings demonstrate a novel role for GC-C signaling in facilitating mucosal wounding and inflammation, and further suggest that this may be mediated, in part, through control of RELMβ production.

Loss of guanylyl cyclase C (GCC) signaling leads to dysfunctional intestinal barrier

Background

Guanylyl Cyclase C (GCC) signaling via uroguanylin (UGN) and guanylin activation is a critical mediator of intestinal fluid homeostasis, intestinal cell proliferation/apoptosis, and tumorigenesis. As a mechanism for some of these effects, we hypothesized that GCC signaling mediates regulation of intestinal barrier function.

Methodology/Principal Findings

Paracellular permeability of intestinal segments was assessed in wild type (WT) and GCC deficient (GCC−/−) mice with and without lipopolysaccharide (LPS) challenge, as well as in UGN deficient (UGN−/−) mice. IFNγ and myosin light chain kinase (MLCK) levels were determined by real time PCR. Expression of tight junction proteins (TJPs), phosphorylation of myosin II regulatory light chain (MLC), and STAT1 activation were examined in intestinal epithelial cells (IECs) and intestinal mucosa. The permeability of Caco-2 and HT-29 IEC monolayers, grown on Transwell filters was determined in the absence and presence of GCC RNA interference (RNAi). We found that intestinal permeability was increased in GCC−/− and UGN−/− mice compared to WT, accompanied by increased IFNγ levels, MLCK and STAT1 activation in IECs. LPS challenge promotes greater IFNγ and STAT1 activation in IECs of GCC−/− mice compared to WT mice. Claudin-2 and JAM-A expression were reduced in GCC deficient intestine; the level of phosphorylated MLC in IECs was significantly increased in GCC−/− and UGN−/− mice compared to WT. GCC knockdown induced MLC phosphorylation, increased permeability in IEC monolayers under basal conditions, and enhanced TNFα and IFNγ-induced monolayer hyperpermeability.

Conclusions/Significance

GCC signaling plays a protective role in the integrity of the intestinal mucosal barrier by regulating MLCK activation and TJ disassembly. GCC signaling activation may therefore represent a novel mechanism in maintaining the small bowel barrier in response to injury.

Clostridium difficile infection in hospitalized children in the United States

OBJECTIVES

To evaluate the trend in Clostridium difficile infection (CDI) among hospitalized children in the United States and to evaluate the severity of and risk factors associated with these cases of CDI.

DESIGN

A retrospective cohort study using the triennial Healthcare Cost and Utilization Project Kids' Inpatient Database for the years 1997, 2000, 2003, and 2006.

SETTING

Hospitalized children in the United States.

PARTICIPANTS

A nationally weighted number of patients (10 474 454) discharged from the hospital, 21 274 of whom had CDI.

MAIN EXPOSURE

Discharge diagnosis of CDI.

MAIN OUTCOME MEASURES

Trend in cases of CDI; effect and severity were measured by length of hospital stay, hospitalization charges, colectomy rate, and death rate.

RESULTS

There was an increasing trend in cases of CDI, from 3565 cases in 1997 to 7779 cases in 2006 (P < .001). Patients with CDI had an increased risk of death (adjusted odds ratio [OR], 1.20; 95% confidence interval [95% CI], 1.01-1.43), colectomy (adjusted OR, 1.36; 95% CI, 1.04-1.79), a longer length of hospital stay (adjusted OR, 4.34; 95% CI, 3.97-4.83), and higher hospitalization charges (adjusted OR, 2.12; 95% CI, 1.98-2.26). There was no trend in death, colectomy, length of hospital stay, or hospitalization charges during the 4 time periods (ie, 1997, 2000, 2003, and 2006). The risk of comorbid diagnoses associated with CDI included inflammatory bowel disease, with an OR of 11.42 (95% CI, 10.16-12.83), and other comorbid diagnoses associated with immunosuppression or antibiotic administration.

CONCLUSIONS

There is an increasing trend in CDI among hospitalized children, and this disease is having a significant effect on these children. In contrast to adults, there is no increasing trend in the severity of CDI in children. Children with medical conditions (including inflammatory bowel disease and immunosuppression) or conditions requiring antibiotic administration are at high risk of CDI.

Lack of guanylate cyclase C results in increased mortality in mice following liver injury

Background

Guanylate Cyclase C (GC-C) expression in the intestine plays a role in the regulation of fluid and ion transport, as well as epithelial cell apoptosis and proliferation. In the adult rat liver, GC-C expression is increased in response to injury. We hypothesized that GC-C is required for repair/recovery from liver injury.

Methods

We subjected wild type (WT) and GC-C deficient mice to acute liver injury with a single injection of the hepatotoxin carbon tetrachloride. Changes in the level of expression of GC-C and its ligands uroguanylin and guanylin were quantified by real-time PCR. Liver morphology, and hepatocyte necrosis, apoptosis and proliferation, were examined at 1-3 days post-injury in mice on a mixed genetic background. Survival was followed for 14 days after carbon tetrachloride injection in wild type and GC-C deficient mice on both a mixed genetic background and on an inbred C57BL6/J background.

Results

GC-C deficient mice on the mixed genetic background nearly all died (median survival of 5 days) following carbon tetrachloride injection while WT littermates experienced only 35% mortality. Elevated levels of TUNEL-positive hepatocyte death on post-injury day 1, increased apoptosis on day 2, and increased areas of centrilobular necrosis on days 2 and 3, were evident in livers from GC-C null mice compared to WT. Collectively these data suggest increased hepatocyte death in the GC-C null mice in the early time period after injury. This corresponds temporally with increased expression of GC-C and its ligands guanylin and uroguanylin in post-injury WT mouse liver. The hepatocyte proliferative response to injury was the same in both genotypes. In contrast, there was no difference in survival between GC-C null and WT mice on the inbred C57BL/6 J background in response to acute liver injury.

Conclusions

Signalling via GC-C promotes hepatocyte survival in vivo and is required for effective recovery from acute toxic injury to the liver in a strain-specific manner.

Teaching and tomorrow: a novel recruitment program for a pediatric subspecialty

OBJECTIVES

: In 2001, the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition created Teaching and Tomorrow, a novel pediatric subspecialty recruitment program to provide prospective fellows the opportunity to participate in the society's annual meeting and to interact with current trainees and members. The aims of this report are to describe participant survey data from the first 4 years of the program and to explore potential influences of participation on outcomes and proposed career choices.

MATERIALS AND METHODS

: Pre- and postprogram surveys were administered during opening and closing breakfast meetings, respectively, to ascertain demographics, certainty of career intent, factors influencing choice of specialty, and anticipated benefits from participation.

RESULTS

: Among 189 applications, 107 (57%) participated and 107 (57%) matriculated into gastroenterology(GI) fellowship. The matriculation rate was similar between participants and nonparticipants. Among applicants who became GI fellows, there was a 42% lower odds of being female than male (OR 0.42; chi = 8.48, P < 0.01). Among participants who completed both pre- and postprogram surveys (n = 91) and who reported certainty about entering GI both before and after, 79% entered GI fellowship. Among participants who reported uncertainty about entering GI both before and after, 8% entered GI. More participants were interested in jobs as clinician-investigators and funded clinical or translational investigators.

CONCLUSIONS

: In a selected population of pediatric residents with high interest in pediatric gastroenterology, there was no difference in the matriculation rate into pediatric GI fellowship training among those who participated compared with those who did not. However, those who eventually matriculated had a higher odds of being male than female. There was a high retention rate of participants who were initially certain and a modest conversion rate of those who were initially uncertain about pursuing a career in pediatric GI.

Heat-stable enterotoxin of Escherichia coli (STa) can stimulate duodenal HCO3(-) secretion via a novel GC-C- and CFTR-independent pathway

The heat-stable enterotoxin of Escherichia coli (STa) is a potent stimulant of intestinal chloride and bicarbonate secretion. Guanylyl cyclase C (GC-C) has been shown to be the primary receptor involved in mediating this response. However, numerous studies have suggested the existence of an alternative STa-binding receptor. The aims of this study were to determine whether a non-GC-C receptor exists for STa and what is the functional relevance of this for intestinal bicarbonate secretion in mice. (125)I-STa-binding experiments were performed with intestinal mucosae from GC-C knockout (KO) and wild type (WT) mice. Subsequently, the functional relevance of an alternative STa-binding receptor was explored by examining STa-, uroguanylin-, and guanylin-stimulated duodenal bicarbonate secretion (DBS) in GC-C KO mice in vitro and in vivo. Significant (125)I-STa-binding occurred in the proximal small intestines of GC-C KO and WT mice. Analysis of binding coefficients and pH dependence showed that (125)I-STa-binding in GC-C KO mice involved a receptor distinct from that of WT mice. Functionally, STa, uroguanylin, and guanylin all stimulated a significant increase in DBS in GC-C KO mice. Uroguanylin- and guanylin-stimulated DBS were significantly inhibited by glibenclamide, but not by 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS). However, STa-stimulated DBS was unaffected by glibenclamide but inhibited by DIDS. Taken together, our results suggest that alternative, non-GC-C, receptors likely exist for STa, uroguanylin, and guanylin in the intestines of mice. While uroguanylin- and guanylin-stimulated DBS are cystic fibrosis transmembrane conductance regulator (CFTR) dependent, STa-stimulated DBS is CFTR independent. Further understanding of this alternative receptor and its signaling pathway may provide important insights into rectification of intestinal bicarbonate secretion in cystic fibrosis.

Molecular cloning and promoter analysis of downregulated in adenoma (DRA)

Downregulated in adenoma (DRA), also referred to as SLC26A3, is an intestinal anion transporter essential for intestinal chloride absorption. Mutations in DRA result in congenital chloride diarrhea. DRA expression has been shown to be induced by differentiation and to be modulated by cytokines. However, mechanisms of DRA gene transcription and its tissue-specific targeting have not yet been investigated. In this study, we cloned a 3,765-bp promoter fragment of human DRA gene and characterized its activity in human colonic LS174T and Caco-2 human colon cell lines. Primer extension identified a single transcriptional initiation site that was identical in both colon cancer cell lines and normal colon. Although hepatic nuclear factor HNF-4 is involved in the basal activity of DRA promoter, sodium butyrate induces its activity in LS174T cells via the binding of Yin Yang 1 (YY1) and GATA transcription factors to their respective cis-elements in promoter region. We also demonstrated a reduction in DRA promoter activity in Caco-2 cells by IFN-gamma, suggesting that regulation of DRA promoter by IFN-gamma may contribute to the pathophysiology of intestinal inflammation. Furthermore, we showed that the DRA promoter fragment is sufficient to drive human growth hormone transgene expression specifically in villus epithelial cells of the small intestine and in differentiated upper crypt and surface epithelial cells of the colon. Our studies provide evidence for the involvement of HNF-4, YY1, and GATA transcription factors in DRA expression in intestinal differentiated epithelial cells.

Human mass balance study of the novel anticancer agent ixabepilone using accelerator mass spectrometry

Ixabepilone (BMS-247550) is a semi-synthetic, microtubule stabilizing epothilone B analogue which is more potent than taxanes and has displayed activity in taxane-resistant patients. The human plasma pharmacokinetics of ixabepilone have been described. However, the excretory pathways and contribution of metabolism to ixabepilone elimination have not been determined. To investigate the elimination pathways of ixabepilone we initiated a mass balance study in cancer patients. Due to autoradiolysis, ixabepilone proved to be very unstable when labeled with conventional [¹⁴C]-levels (100 μCi in a typical human radio-tracer study). This necessitated the use of much lower levels of [¹⁴C]-labeling and an ultra-sensitive detection method, Accelerator Mass Spectrometry (AMS). Eight patients with advanced cancer (3 males, 5 females; median age 54.5 y; performance status 0–2) received an intravenous dose of 70 mg, 80 nCi of [¹⁴C]ixabepilone over 3 h. Plasma, urine and faeces were collected up to 7 days after administration and total radioactivity (TRA) was determined using AMS. Ixabepilone in plasma and urine was quantitated using a validated LC-MS/MS method. Mean recovery of ixabepilone-derived radioactivity was 77.3% of dose. Fecal excretion was 52.2% and urinary excretion was 25.1%. Only a minor part of TRA is accounted for by unchanged ixabepilone in both plasma and urine, which indicates that metabolism is a major elimination mechanism for this drug. Future studies should focus on structural elucidation of ixabepilone metabolites and characterization of their activities.

Gaucher disease: progressive mesenteric and mediastinal lymphadenopathy despite enzyme therapy

A 5-year-old male with Gaucher's disease type 3 developed progressive mesenteric and mediastinal lymphadenopathy over 12 months, despite enzyme replacement therapy, contributing to the development of a protein-losing enteropathy. These complications are unique, indicating poorly accessible, differentially responsive compartments in patients with Gaucher's disease who are receiving enzyme therapy.

Novel mechanism of cyclic AMP mediated extracellular signal regulated kinase activation in an intestinal cell line

The extracellular signal regulated kinase (ERK1/2) signaling cascade has been implicated as both a pro-apoptotic and anti-apoptotic pathway depending on cell type and context. In the T84 intestinal epithelial cell line, cAMP activates ERK1/2 resulting in the inhibition of apoptosis. Cyclic-AMP signaling relies on the binding and activation of a cAMP binding protein. In most cell types, the majority of this signaling occurs through an isoform of protein kinase A (PKAI or PKAII). Despite evidence to the contrary, we hypothesized that ERK1/2 activation is through a PKA isoform. Pharmacological activators and inhibitors of PKA as well as siRNA were used to further interrogate this potential signaling pathway. Our results demonstrate that at doses sufficient to increase PKA activity, PKAII specific cAMP analogs activate ERK1/2 while PKAI analogs do not. Pharmacological inhibition of the PKAII regulatory subunit and catalytic subunit as well as siRNA knockdown of the catalytic subunit blocks ERK1/2 activation. We conclude that in the T84 cell line, cAMP binding to the PKAII regulatory subunit leads to the subsequent phosphorylation of ERK1/2 and provides insight into the mechanism of cAMP mediated survival signaling in the intestinal epithelium. These results directly implicate PKAII as a mediator of cell survival in T84 cells and provide evidence for an additional means by which cAMP can influence intestinal cell turnover.

Potential of blood eosinophils, eosinophil-derived neurotoxin, and eotaxin-3 as biomarkers of eosinophilic esophagitis

BACKGROUND & AIMS

Eosinophilic esophagitis (EE) is an increasingly recognized disorder characterized by eosinophilic inflammation of the esophageal mucosa, and typically requires serial invasive endoscopic biopsy examinations to document the characteristic histologic features of the disorder. The aim of this study was to identify noninvasive biomarkers that correlated with disease activity and response to treatment as measured by esophageal eosinophilia.

METHODS

A prospective, cross-sectional analysis was performed on 47 pediatric patients undergoing endoscopic evaluation of possible EE. Blood samples were collected for measurement of peripheral blood absolute eosinophil count (AEC) and levels of eosinophil-derived neurotoxin (EDN), eotaxin-1, -2, and -3, and interleukin-5. Stool samples were collected for measurement of EDN. Biomarker levels were correlated with esophageal eosinophil density, and differences in biomarker levels based on disease activity and treatment were determined.

RESULTS

AEC, plasma EDN levels, and eotaxin-3 levels significantly correlated with esophageal eosinophil density (AEC: r = 0.56, P < .0001; EDN: r = 0.54, P < .0001; eotaxin-3: r = 0.32, P = .04), and were increased in patients with active EE vs controls (AEC: 440 vs 140 eosinophils/muL, P < .05; EDN: 50.3 vs 31.1 ng/mL, P = .01; eotaxin-3: 37.7 vs 11.5 pg/mL, P = .01). Cut-off values were established to maximize the sensitivity, specificity, and predictive values of these biomarkers alone and in combination. Eotaxin-1, eotaxin-2, interleukin-5, and fecal EDN levels did not correlate with esophageal eosinophil density, and were not increased in active EE vs controls or those with inactive EE.

CONCLUSIONS

These data show that blood levels of AEC, EDN, and eotaxin-3 may have value as noninvasive biomarkers for monitoring EE.

A randomized, double-blind, placebo-controlled trial of fluticasone propionate for pediatric eosinophilic esophagitis

BACKGROUND & AIMS

Eosinophilic esophagitis is an increasingly recognized disorder with distinctive endoscopic, histologic, and allergic features. Although several therapies are advocated, no placebo-controlled trials have been conducted. We aimed to determine the efficacy of swallowed fluticasone propionate (FP) in the treatment of eosinophilic esophagitis.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial of swallowed FP in pediatric patients with active eosinophilic esophagitis. Thirty-six patients were randomly assigned to receive either 880 mug of FP (21 patients) or placebo (15 patients) divided twice daily for 3 months. The primary end point was histologic remission, defined by a peak eosinophil count of </=1 eosinophil in all 400x fields in both the proximal and distal esophagus.

RESULTS

Fifty percent of FP-treated patients achieved histologic remission compared with 9% of patients receiving placebo (P = .047). FP decreased esophageal eosinophil levels, with a more pronounced effect in nonallergic individuals (65.9 +/- 25.3 vs 1.4 +/- 1.1 eosinophils/high-power field in the proximal esophagus [P = .03] and 84.6 +/- 19.7 vs 19.6 +/- 12.9 eosinophils/high-power field in the distal esophagus [P = .04]). Resolution of vomiting occurred more frequently with FP than placebo (67% vs 27%; P = .04). FP-induced resolution of mucosal eosinophilia was associated with resolution of endoscopic findings, epithelial hyperplasia, younger age (P = .0003), shorter height (P = .002), and lighter weight (P = .02). Effective treatment with FP decreased the number of CD8(+) T lymphocytes and mast cells in both the proximal and distal esophagus (P < .05).

CONCLUSIONS

Swallowed FP is effective in inducing histologic remission in eosinophilic esophagitis, with a more pronounced effect in nonallergic and younger individuals, especially in the proximal esophagus.

The proximal convoluted tubule is a target for the uroguanylin-regulated natriuretic response

OBJECTIVES AND METHODS

Guanylin and uroguanylin are peptides synthesized in the intestine and kidney that are postulated to have both paracrine and endocrine functions, forming a potential enteric-renal link to coordinate salt ingestion with natriuresis. To explore the in vivo role of guanylin and uroguanylin in the regulation of sodium excretion, we used gene-targeted mice in which the uroguanylin, guanylin or the peptide receptor guanylate cyclase C gene expression had been ablated.

RESULTS

Metabolic balance studies demonstrated that there was impaired excretion of a sodium load in uroguanylin (but not in guanylin or guanylate cyclase C) knockout mice. Uroguanylin-dependent natriuresis occurred without an increase in circulating prouroguanylin. A distinct morphological phenotype was present in the proximal convoluted tubules of uroguanylin knockout animals after an enteral salt loading. Marked vacuolization of the proximal convoluted tubule epithelial cells was observed by using light and electron microscopy. There was also a change in the distribution of the sodium hydrogen exchanger 3 (NHE3) after an enteral salt loading. In wild-type animals, there was a partial redistribution of NHE3 from the villus fraction to the less accessible submicrovillus membrane compartment, but this effect was less apparent in uroguanylin knockout animals, presumably resulting in greater Na/H exchange.

CONCLUSIONS

Together, these findings further establish a role for uroguanylin in fluid homeostasis and support a role for uroguanylin as an integral component of a signaling mechanism that mediates changes in Na excretion in response to an enteral salt loading. Proximal tubular NHE3 activity is a possible target for uroguanylin-mediated changes in Na excretion.

Effect of triglyceride structure on fecal excretion of 13C-labeled triglycerides

OBJECTIVE

The aim of this work was to determine the effects of specific changes in the structure of (13)C-labeled triglyceride (TG*) on its fecal excretion relative to total stool fat excretion determined simultaneously in patients with reduced exocrine pancreatic function.

METHODS

A series of 47 studies were conducted in 26 young cystic fibrosis (CF) patients and 11 adult patients with chronic pancreatitis over a five year period. Each test consisted of ingesting a single high fat test meal containing both (13)C-labeled triglyceride (TG*) and dysprosium chloride (DyCl(3)) a nonabsorbable marker of intestinal transit; in most studies the food colorant brilliant blue (FD&C blue #1) was administered along with the DyCl(3). The TG*s tested were: P*P*P* = TRIPALMITIN-1,1,1-(13)C(3); SO*S = 2-OCTANOYL-1,3-DISTEARIN-2-octanoyl-1,2-(13)C(2); and P*LP* = 2-LAURYL-1,3-DIPALMITIN-dipalmitoyl-1,1,2,2-(13)C(4). Ingestion of the test meal was followed by collection of individual stools for at least 72 hours. Stools were analyzed for (13)C-Excess ((13)C*), total fat, and Dy.

RESULTS

Excretion of P*LP* showed a high degree of linear correlation with stool fat (r(2) = 0.924) over a wide-range of fecal fat values. Excretion of SO*S was also significantly correlated with stool fat, but its excretion was less than 10% at all levels of steatorrhea and the slope of the regression line relating TG* excretion to stool fat was some four to five times smaller than observed for P*LP*. Fecal excretion of P*P*P* was highly correlated with stool fat (r(2) = 0.941) in patients with moderate steatorrhea (<25 g fat/24 hours) and the slope of the regression line (3.20) was considerably greater than for P*LP*. Only results from those studies in which stool collections were complete (Dy excretion >90%) were utilized in the statistical comparisons (36 of 47 studies).

CONCLUSIONS

The observed highly significant linear correlation between P*LP* and stool fat over the entire range of steatorrhea suggests that P*LP* excretion may be a suitable surrogate for fecal fat in patients with reduced exocrine pancreatic function. Because fecal excretion of TG* administered as described can be accurately determined by sampling only two visually marked stools, development of a noninvasive test to replace the current 72-hour stool fat test using this approach is possible. Use of other engineered TG*s and/or labeled fatty acids, may provide a method for non-invasive in vivo assessment of the specific defect(s) leading to steatorrhea in other patient groups.

Eotaxin-3 and a uniquely conserved gene-expression profile in eosinophilic esophagitis

Eosinophilic esophagitis (EE) is an emerging disorder with a poorly understood pathogenesis. In order to define disease mechanisms, we took an empirical approach analyzing esophageal tissue by a genome-wide microarray expression analysis. EE patients had a striking transcript signature involving 1% of the human genome that was remarkably conserved across sex, age, and allergic status and was distinct from that associated with non-EE chronic esophagitis. Notably, the gene encoding the eosinophil-specific chemoattractant eotaxin-3 (also known as CCL26) was the most highly induced gene in EE patients compared with its expression level in healthy individuals. Esophageal eotaxin-3 mRNA and protein levels strongly correlated with tissue eosinophilia and mastocytosis. Furthermore, a single-nucleotide polymorphism in the human eotaxin-3 gene was associated with disease susceptibility. Finally, mice deficient in the eotaxin receptor (also known as CCR3) were protected from experimental EE. These results implicate eotaxin-3 as a critical effector molecule for EE and provide insight into disease pathogenesis.

Novel effects of the prototype translocating Escherichia coli, strain C25 on intestinal epithelial structure and barrier function

Intestinal bacteria play an etiologic role in triggering and perpetuating chronic inflammatory bowel disorders. However, the precise mechanisms whereby the gut microflora influences intestinal cell function remain undefined. Therefore, the effects of the non-pathogenic prototype translocating Escherichia coli, strain C25 on the barrier properties of human T84 and Madine-Darby canine kidney type 1 epithelial cells were examined. T-84 cells were also infected with commensal E. coil, strains F18 and HB101, and enterohaemorrhagic E. coli, serotype O157:H7. Strains F18 and HB101 had no effect on transepithelial electrical resistance (TER) of T84 monolayers. By contrast, epithelial cells infected with strain C25 displayed a time-dependent decrease in TER, preceded by an altered distribution of the cytoskeletal protein alpha-actinin, comparable to infection with E. coli O157:H7. E. coli C25 infection also led to activation of nuclear factor kappaB (NF-kappaB), interleukin-8 secretion and alterations in localization of claudin-1, but not zona occludens-1 or claudin-4, in T84 cells. There were adherent C25 bacteria on the intact apical surface of infected T84 cells, while mitochondria appeared swollen and vacuolated. These novel findings demonstrate the ability of a translocating commensal bacterium to adhere to and modulate intestinal epithelial barrier function and to induce morphological changes in a manner distinct from the known enteric pathogen, E. coli O157:H7.

Lack of guanylyl cyclase C, the receptor for Escherichia coli heat-stable enterotoxin, results in reduced polyp formation and increased apoptosis in the multiple intestinal neoplasia (Min) mouse model

Guanylyl cyclase C (GC-C), a transmembrane receptor for bacterial heat-stable enterotoxin and the mammalian peptides guanylin and uroguanylin, mediates intestinal ion secretion and affects intestinal cell growth via cyclic GMP signaling. In intestinal tumors, GC-C expression is maintained while guanylin and uroguanylin expression is lost, suggesting a role for GC-C activation in tumor formation or growth. We show by in situ hybridization that GC-C expression is retained in adenomas from multiple intestinal neoplasia (Apc(Min/+)) mice. In order to determine the in vivo role of GC-C in intestinal tumorigenesis, we generated Apc(Min/+) mice homozygous for a targeted deletion of the gene encoding GC-C and hypothesized that these mice would have increased tumor multiplicity and size compared to wild-type Apc(Min/+) mice on the same genetic background. In contrast, the absence of GC-C resulted in a reduction of median polyp number by 55%. There was no change in the median diameter of polyps, suggesting no effect on tumor growth. Somatic loss of the wild-type Apc allele, an initiating event in intestinal tumorigenesis, also occurred in polyps from GC-C-deficient Apc(Min/+) mice. We have found increased levels of apoptosis as well as increased caspase-3 and caspase-7 gene expression in the intestines of GC-C-deficient Apc(Min/+) mice compared with Apc(Min/+) mice. We propose that these alterations are a possible compensatory mechanism by which loss of GC-C signaling also affects tumorigenesis.

Prevalence and outcome of allergic colitis in healthy infants with rectal bleeding: a prospective cohort study

OBJECTIVES

Allergic colitis is often diagnosed clinically in healthy infants with rectal bleeding and often treated with costly hypoallergenic formula. The true prevalence of allergic colitis is unknown. We tested the hypothesis that allergic colitis is overdiagnosed in healthy infants with rectal bleeding. The authors also determined whether rectal bleeding in infants without allergic colitis would resolve without diet change.

METHODS

For the purposes of this study, allergic colitis was defined histologically as colonic mucosa with >or= 6 eosinophils per high power field and/or eosinophils in colonic crypts or muscularis mucosae. We surveyed all 56 Ohio NASPGHAN members to determine standard practice regarding the evaluation of rectal bleeding in infants. In addition, infants <or= 6 months old with rectal bleeding were recruited from the referral area of Cincinnati Children's Hospital Medical Center. All infants underwent flexible sigmoidoscopy with biopsies at 5, 10 and 15 cm. Formula or maternal diet was changed only for infants with histologic findings of allergic colitis as defined. Study subjects were followed for 9 weeks.

RESULTS

In the survey of NASPGHAN members, 84% indicated they would empirically change the diet of an infant with rectal bleeding to treat presumed allergic colitis. In our study population, however, only 14 of 22 (64%; 95% confidence interval, 41-83) infants with rectal bleeding had allergic colitis. Five (23%) had normal biopsies and three (14%) had nonspecific colitis. Rectal bleeding in all infants with normal biopsies or nonspecific colitis resolved without diet change except for 1 infant subsequently diagnosed with infantile inflammatory bowel disease.

CONCLUSION

A significant proportion of infants with rectal bleeding may not have allergic colitis and may undergo unnecessary, expensive formula or maternal diet changes that may discourage breast-feeding.