Review Articles in 2012

Richard Guerrant and colleagues discuss the growing evidence that vicious cycles of early childhood enteric infections and malnutrition are associated with obesity and its comorbidities in later life, forming a triple burden of poverty. The potential mechanisms and interventions that must be understood and applied to prevent this loss of human potential are also presented.

The enteric nervous system (ENS) arises from neural crest-derived cells. Here, Heather Young and colleagues provide an overview of the progress made in the past five years in our understanding of ENS development and the potential involvement of defects in ENS development in paediatric motility disorders.

Ischaemia–reperfusion injury (IRI) in the liver is a major complication of transplantation. This Review outlines our current understanding of the cellular and molecular mechanisms that underlie liver IRI and summarizes the latest progress in large animal models and clinical trials of liver IRI.

Upper gastrointestinal tract cancers (UGICs) pose a major health risk around the world, and therapeutic improvements have been very slow and small. Increased understanding of the role of microRNAs in UGICs could lead to novel prevention strategies, early detection and improved therapeutics for these cancers.

The permeability of the intestinal epithelial barrier has a central role in the regulation of fluid and nutrient intake as well as in the control of the passage of pathogens. In this Review, Michel Neunlist and colleagues summarize current studies characterizing neuronal and glial effects on the intestinal epithelial barrier and outline the novel concept of a digestive neuronal–glial–epithelial unit.

As the burden of hepatocellular carcinoma (HCC) continues to increase, attention turns to the appropriate management of the disease. In this Review, the authors discuss and critique the currently available medical interventions for the treatment and management of HCC, as well as introduce future developments in the field.

IBS is a common disorder that can have an enormous negative effect on patients and society as a whole; however, many patients do not achieve adequate symptom relief with the currently available therapies. In this Review, Magnus Halland and Nicholas Talley discuss the latest treatments for IBS, including novel nonpharmacological and pharmacological approaches.

Targets for the medical management of NAFLD remain elusive and no medications have been approved by the FDA to date. Instead, lifestyle modification via diet and exercise is most commonly recommended. The optimal physical activity regimen in terms of both effectiveness and compliance remains to be determined and is the focus of this Review.

Colorectal cancer (CRC) largely affects patients >75 years old, yet no evidence-based guidelines are available for this age group. In this article, Riccardo Audisio and Demetris Papamichael discuss the various treatment options available for older patients with CRC and suggest that treatment should be tailored to the individual patient.

This Review focuses on several of the hormones released by the gastrointestinal tract prior to or during nutrient ingestion that have key roles in maintaining energy balance. These hormones include the gastric orexigenic hormone, ghrelin, and the distal L cell anorex-igenic and metabolic hormones, glucagon-like peptide (GLP) 1, GLP 2, oxyntomodulin and peptide YY. Their biological actions are outlined, as well as potential or actual uses as treatments for obesity and type 2 diabetes mellitus.

Hepatitis E is common in developing countries, and occasional cases of this disease have been identified in developed countries. The currently available diagnostic tests have undergone limited testing and often yield discordant results. In this article, Rakesh Aggarwal reviews the information on diagnosis of hepatitis E, including past and current diagnostic tests.

The incidence of eosinophilic oesophagitis (EoE) has been increasing since it was defined as a distinct disease entity in the 1990s. In this Review, Alex Straumann and Alain Schoepfer define EoE and describe its aetiology and pathogenesis. They also discuss strengths and limitations of existing therapeutic approaches.

Gastrointestinal motility results from coordinated contractions of the smooth muscle tissues forming thetunica muscularisof the alimentary canal. Smooth muscle cells are organized into an electrical syncytium that also incorporates interstitial cells. Myogenic, neural and humoral factors provide integrated control of contractile activity. Kenton Sanders and colleagues provide an overview of the cells and mechanisms that generate and regulate smooth muscle contractile behaviour and gastrointestinal motility.

The human gut harbours a vast array of micro-organisms and the benefits of these bacteria should not be forgotten. Here, Flint and colleagues discuss the role of the gut microbiota in nutrition and health, describing the development of these bacteria in the healthy gut, and their positive influences on microbial and human metabolism.

Diarrhoea and constipation are two of the most common symptoms encountered by primary care physicians and gastroenterologists. Luminally acting agents are less likely to cause adverse events than drugs with systemic actions. This Review discusses luminally acting treatments for diarrhoea and constipation, focussing on new agents and those that are currently in clinical trials.

The gut microbiota is recognized to have a role in the development of obesity, and evidence indicates that the composition of the microbiota is modified after bariatric surgery. This Review summarizes current knowledge of the potential mechanisms by which major modifications of the digestive tract after bariatric surgery can affect the composition of the gut microbiota.

IBD is emerging as a worldwide epidemic. Patients with IBD often have an abnormal gut microbiota; however, it is unknown whether this feature is a cause or a consequence of disease. In this article, Francisco Guarner and colleagues review our current knowledge of the human gut microbiota, describe changes observed in patients with IBD and discuss whether such changes might explain the pathophysiological characteristics of IBD.

Enteric glia encompass a diverse range of glial cells that populate the gastrointestinal tract. In this Review, Gulbransen & Sharkey provide a timely update on the different types of enteric glia and their role in normal and abnormal gut function. In addition, key areas in which further knowledge is needed to fully appreciate the physiology of these cells are also highlighted.

The development of the gut microbiota occurs early in life. As outlined in this Review by Isolauri and colleagues, the initial microbial colonization of the gut, and indeed of the rest of the human body, is a stepwise process and interactions between these colonizing bacteria and the human host ultimately have a key influence on health and disease.

Postoperative ileus is a common complication of abdominal surgery and places a considerable burden on health-care systems. In this Review, the authors outline evidence that postoperative ileus is mediated by the immune system and highlight new therapeutic approaches to interrupt the inflammatory cascade that characterizes this condition.