Benjamin D. Gold

ideR, an Essential Gene in Mycobacterium tuberculosis: Role of IdeR in Iron-Dependent Gene Expression, Iron Metabolism, and Oxidative Stress Response

ABSTRACT The mycobacterial IdeR protein is a metal-dependent regulator of the DtxR (diphtheria toxin repressor) family. In the presence of iron, it binds to a specific DNA sequence in the promoter regions of the genes that it regulates, thus controlling their transcription. In this study, we provide evidence that ideR is an essential gene in Mycobacterium tuberculosis. ideR cannot normally be disrupted in this mycobacterium in the absence of a second functional copy of the gene. However, a rare ideR mutant was obtained in which the lethal effects of ideR inactivation were alleviated by a second-site suppressor mutation and which exhibited restricted iron assimilation capacity. Studies of this strain and a derivative in which IdeR expression was restored allowed us to identify phenotypic effects resulting from ideR inactivation. Using DNA microarrays, the iron-dependent transcriptional profiles of the wild-type, ideR mutant, and ideR-complemented mutant strains were analyzed, and the genes regulated by iron and IdeR were identified. These genes encode a variety of proteins, including putative transporters, proteins involved in siderophore synthesis and iron storage, members of the PE/PPE family, a membrane protein involved in virulence, transcriptional regulators, and enzymes involved in lipid metabolism.

A Global, Evidence-Based Consensus on the Definition of Gastroesophageal Reflux Disease in the Pediatric Population

OBJECTIVES:To develop an international consensus on the definition of gastroesophageal reflux disease (GERD) in the pediatric population.METHODS:Using the Delphi process, a set of statements was developed and voted on by an international panel of eight pediatric gastroenterologists. Statements were based on systematic literature searches using Medline, EMBASE, and CINAHL. Voting was conducted using a six-point scale, with consensus defined, a priori, as agreed by 75% of the group. The strength of each statement was assessed using the GRADE system.RESULTS:There were four rounds of voting. In the final vote, consensus was reached on 98% of the 59 statements. In this vote, 95% of the statements were accepted by seven of eight voters. Consensus items of particular note were: (i) GERD is present when reflux of gastric contents causes troublesome symptoms and/or complications, but this definition is complicated by unreliable reporting of symptoms in children under the age of ∼8 years; (ii) histology has limited use in establishing or excluding a diagnosis of GERD; its primary role is to exclude other conditions; (iii) Barretts esophagus should be defined as esophageal metaplasia that is intestinal metaplasia positive or negative; and (iv) extraesophageal conditions may be associated with GERD, but for most of these conditions causality remains to be established.CONCLUSIONS:The consensus statements that comprise the Definition of GERD in the Pediatric Population were developed through a rigorous process. These statements are intended to be used for the development of future clinical practice guidelines and as a basis for clinical trials.

Differentiating ulcerative colitis from Crohn disease in children and young adults: report of a working group of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition and the Crohn's and Colitis Foundation of America.

Background: Studies of pediatric inflammatory bowel disease (IBD) have varied in the criteria used to classify patients as having Crohn disease (CD), ulcerative colitis (UC), or indeterminate colitis (IC). Patients undergoing an initial evaluation for IBD will often undergo a series of diagnostic tests, including barium upper gastrointestinal series with small bowel follow-through, abdominal CT, upper endoscopy, and colonoscopy with biopsies. Other tests performed less frequently include magnetic resonance imaging scans, serological testing, and capsule endoscopy. The large amount of clinical information obtained may make a physician uncertain as to whether to label a patient as having CD or UC. Nevertheless, to facilitate the conduct of epidemiological studies in children, to allow the entry of children into clinical trials, and to allow physicians to more clearly discuss diagnosis with their patients, it is important that clinicians be able to differentiate between CD and UC. Methods: A consensus conference regarding the diagnosis and classification of pediatric IBD was organized by the Crohns and Colitis Foundation of America. The meeting included 10 pediatric gastroenterologists and 4 pediatric pathologists. The primary aim was to determine the utility of endoscopy and histology in establishing the diagnosis of CD and UC. Each member of the group was assigned a topic for review. Topics evaluated included differentiating inflammatory bowel disease from acute self-limited colitis, endoscopic and histological features that allow differentiation between CD and UC, upper endoscopic features seen in both CD and UC, ileal inflammation and “backwash ileitis” in UC, patchiness and rectal sparing in pediatric IBD, periappendiceal inflammation in CD and UC, and definitions of IC. Results: Patients with UC may have histological features such as microscopic inflammation of the ileum, histological gastritis, periappendiceal inflammation, patchiness, and relative rectal sparing at the time of diagnosis. These findings should not prompt the clinician to change the diagnosis from UC to CD. Other endoscopic findings, such as macroscopic cobblestoning, segmental colitis, ileal stenosis and ulceration, perianal disease, and multiple granulomas in the small bowel or colon more strongly suggest a diagnosis of CD. An algorithm is provided to enable the clinician to differentiate more reliably between these 2 entities. Conclusions: The recommendations and algorithm presented here aim to assist the clinician in differentiating childhood UC from CD. We hope the recommendations in this report will reduce variability among practitioners in how they use the terms “ulcerative colitis,” “Crohn disease,” and “indeterminate colitis.” The authors hope that progress being made in genetic, serological, and imaging studies leads to more reliable phenotyping.

A Comprehensive Review of the Natural History of Helicobacter pylori Infection in Children

Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life.

Differential expression of iron-, carbon-, and oxygen- responsive mycobacterial genes in the lungs of chronically infected mice and tuberculosis patients

Pathogenetic processes that facilitate the entry, replication, and persistence of Mycobacterium tuberculosis (MTB) in the mammalian host likely include the regulated expression of specific sets of genes at different stages of infection. Identification of genes that are differentially expressed in vivo would provide insights into host-pathogen interactions in tuberculosis (TB); this approach might be particularly valuable for the study of human TB, where experimental opportunities are limited. In this study, the levels of selected MTB mRNAs were quantified in vitro in axenic culture, in vivo in the lungs of mice, and in lung specimens obtained from TB patients with active disease. We report the differential expression of MTB mRNAs associated with iron limitation, alternative carbon metabolism, and cellular hypoxia, conditions that are thought to exist within the granulomatous lesions of TB, in the lungs of wild-type C57BL/6 mice as compared with bacteria grown in vitro. Analysis of the same set of mRNAs in lung specimens obtained from TB patients revealed differences in MTB gene expression in humans as compared with mice.

Evidence-based Guidelines From ESPGHAN and NASPGHAN for Helicobacter pylori Infection in Children

Objective: As the clinical implications of Helicobacter pylori infection in children and adolescents continue to evolve, ESPGHAN and NASPGHAN jointly renewed clinical guidelines using a standardized evidence-based approach to develop updated recommendations for children and adolescents in North America and Europe. Methods: An international panel of 11 pediatric gastroenterologists, 2 epidemiologists, 1 microbiologist, and 1 pathologist was selected by societies that developed evidence-based guidelines based on the Delphi process with anonymous voting in a final face-to-face meeting. A systematic literature search was performed on 8 databases of relevance including publications from January 2000 to December 2009. After excluding nonrelevant publications, tables of evidence were constructed for different focus areas according to the Oxford classification. Statements and recommendations were formulated in the following areas: whom to test, how to test, whom to treat, and how to treat. Grades of evidence were assigned to each recommendation based on the GRADE system. Results: A total of 2290 publications were identified, from which 738 were finally reviewed. A total of 21 recommendations were generated, and an algorithm was proposed by the joint committee providing evidence-based guidelines on the diagnostic workup and treatment of children with H pylori infection. Conclusions: These clinical practice guidelines represent updated, best-available evidence and are meant for children and adolescents living in Europe and North America, but they may not apply to those living on other continents, particularly in developing countries with a high H pylori infection rate and limited health care resources.

Lansoprazole for children with poorly controlled asthma: a randomized controlled trial.

CONTEXT Asymptomatic gastroesophageal reflux (GER) is prevalent in children with asthma. Untreated GER has been postulated to be a cause of inadequate asthma control in children despite inhaled corticosteroid treatment, but it is not known whether treatment with proton pump inhibitors improves asthma control. OBJECTIVE To determine whether lansoprazole is effective in reducing asthma symptoms in children without overt GER. DESIGN, SETTING, AND PARTICIPANTS The Study of Acid Reflux in Children With Asthma, a randomized, masked, placebo-controlled, parallel clinical trial that compared lansoprazole with placebo in children with poor asthma control who were receiving inhaled corticosteroid treatment. Three hundred six participants enrolled from April 2007 to September 2010 at 19 US academic clinical centers were followed up for 24 weeks. A subgroup had an esophageal pH study before randomization. INTERVENTION Participating children were randomly assigned to receive either lansoprazole, 15 mg/d if weighing less than 30 kg or 30 mg/d if weighing 30 kg or more (n = 149), or placebo (n = 157). MAIN OUTCOME MEASURES The primary outcome measure was change in Asthma Control Questionnaire (ACQ) score (range, 0-6; a 0.5-unit change is considered clinically meaningful). Secondary outcome measures included lung function measures, asthma-related quality of life, and episodes of poor asthma control. RESULTS The mean age was 11 years (SD, 3 years). The mean difference in change (lansoprazole minus placebo) in the ACQ score was 0.2 units (95% CI, 0.0-0.3 units). There were no statistically significant differences in the mean difference in change for the secondary outcomes of forced expiratory volume in the first second (0.0 L; 95% CI, -0.1 to 0.1 L), asthma-related quality of life (-0.1; 95% CI, -0.3 to 0.1), or rate of episodes of poor asthma control (relative risk, 1.2; 95% CI, 0.9-1.5). Among the 115 children with esophageal pH studies, the prevalence of GER was 43%. In the subgroup with a positive pH study, no treatment effect for lansoprazole vs placebo was observed for any asthma outcome. Children treated with lansoprazole reported more respiratory infections (relative risk, 1.3 [95% CI, 1.1-1.6]). CONCLUSION In this trial of children with poorly controlled asthma without symptoms of GER who were using inhaled corticosteroids, the addition of lansoprazole, compared with placebo, improved neither symptoms nor lung function but was associated with increased adverse events. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00442013.

High Prevalence of Helicobacter pylori in the Alaska Native Population and Association with Low Serum Ferritin Levels in Young Adults

ABSTRACT Iron deficiency anemia is a common public health problem in the Alaska Native population. Yet, a clear etiology has eluded researchers for decades. Previous studies suggested a link betweenHelicobacter pylori infection, gastrointestinal blood loss due to hemorrhagic gastritis, and generalized iron deficiency anemia in adult Alaska Natives. Therefore, we examined the association between the prevalence of H. pylori-specific immunoglobulin G (IgG) and serum ferritin levels, a marker of iron deficiency. A random sample of 2,080 serum samples from Alaska Native residents drawn between 1980 and 1986 from residents in 13 regions was selected, and the samples were stratified by age, sex, and region. Overall, 75% were positive for H. pylori-specific IgG. The rate of H. pylori seropositivity increased with age; by age 14 years, 78% of the residents were positive. There were no gender differences inH. pylori seropositivity. However, marked regional differences were observed. Serum ferritin levels of <12 ng/ml were found most commonly among persons <20 years of age and among women of childbearing age. A significant association between low serum ferritin levels and prevalence of H. pylori-specific IgG was found, particularly for people aged less than 20 years. H. pylorimay be a factor contributing to the iron deficiency anemia in the Alaska Native population.

Use Caution with Serologic Testing for Helicobacter pylori Infection in Children

Commercial serologic assays accurately detect adult Helicobacter pylori infection. Their use in children remains controversial. An ELISA to detect H. pylori IgG in children was developed and compared with three commercial assays. ELISA standardization was done with sera from all ages and validation was done with another cohort of sera with known H. pylori status. Three commercial serologic assays were subsequently compared against this pediatric ELISA at independent sites, at which 142 pediatric serum samples from different countries were evaluated. The pediatric ELISA was 91.4% sensitive. Assay 3 demonstrated a sensitivity of 78%. Less sensitivity was observed for assay 1 (70%) and assay 2 (63%). Accuracy of commercial assays was greatly reduced when sera from developing countries and younger ages were evaluated. Results of serologic tests used to diagnose H. pylori should be interpreted with caution when evaluating children with abdominal pain. Accurate serologic assays in children may be more important for epidemiologic research than for clinical decision making.

Development of extraintestinal manifestations in pediatric patients with inflammatory bowel disease.

Background: Extraintestinal manifestations (EIMs) in pediatric patients with inflammatory bowel disease (IBD) are poorly characterized. We examined the prevalence of EIMs at diagnosis, subsequent incidence, and risk factors for EIMs. Methods: Data for 1649 patients from the PediIBD Consortium Registry, diagnosed with IBD before 18 years of age (1007 [61%] with Crohns disease, 471 [29%] with ulcerative colitis, and 171 [10%] with indeterminate colitis), were analyzed using logistic regression, Kaplan–Meier, log rank tests, and Cox models. Results: EIMs were reported prior to IBD diagnosis in 97 of 1649 patients (6%). Older children at diagnosis had higher rates compared with younger children, and arthritis (26%) and aphthous stomatitis (21%) were most common. Among the 1552 patients without EIM at diagnosis, 290 developed at least 1 EIM. Kaplan–Meier estimates of cumulative incidence were 9% at 1 year, 19% at 5 years, and 29% at 15 years after diagnosis. Incidence did not differ by IBD type (P = 0.20), age at diagnosis (P = 0.22), or race/ethnicity (P = 0.24). Arthritis (17%) and osteopenia/osteoporosis (15%) were the most common EIMs after IBD diagnosis. Conclusions: In our large cohort of pediatric IBD patients, 6% had at least 1 EIM before diagnosis of IBD. At least 1 EIM will develop in 29% within 15 years of diagnosis. The incidence of EIMs both before and after diagnosis of IBD differs by type of EIM and may be slightly higher in girls, but is independent of the type of IBD, age at diagnosis, and race/ethnicity.