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The Gut Microbiome in Pediatrics

Introduction The human gastrointestinal (GI) tract represents one of the largest interfaces between the host, environmental factors, and antigens. In addition to food and liquids, an abundance of environmental microorganisms and xenobiotics pass through the GI tract daily, posing a potential threat on intestinal health. The collection of bacteria, fungi, viruses, and yeasts in the GI tract, termed gut microbiota, can be considered a microbial organ…

Bile Acid Physiology and Alterations in the Enterohepatic Circulation

Introduction Bile acids are essential in the processing of dietary lipids and serve at least four major functions: (1) Bile acids aggregate and form micelles in the upper small intestine, which help to solubilize lipolytic products, cholesterol, and fat-soluble vitamins, thereby facilitating absorption across the intestinal epithelium. (2) Bile acids stimulate bile flow during their secretion across the biliary canaliculus. (3) Bile acids are major regulators…

Basic Aspects of Digestion and Absorption

Introduction The gastrointestinal (GI) tract performs the essential function of receiving, digesting, and absorbing nutrients from our diet. Digestion is the mechanical and chemical enzymatic breakdown of the food we consume. Absorption is the mobilization of digestion products across the gut to the bloodstream, from where they are destined to be utilized. The digestive system is also equipped to recycle the significant volume of fluid generated…

Development of the Gastrointestinal Tract

Introduction In this chapter we will describe the process of how a complex three-dimensional digestive system with regional differentiation stems from a primitive endodermal tube-like structure. The dramatic cellular and molecular changes seen in gastrointestinal (GI) development guide our understanding for many of the congenital and acquired forms of GI diseases. Included is a review of early patterning, later differentiation, and proliferation into organ systems, plus…

Gastrointestinal Diseases Related to Nutrition

Pancreatitis Acute pancreatitis is an example of a disease process possibly affected by method of feeding (total parenteral nutrition [TPN] versus total enteral nutrition [TEN]). In a prospective study of 54 patients with acute mild pancreatitis, catheter sepsis was 10 times higher in the TPN group than in control subjects who received intravenous fluids only. In the same study, pneumothorax occurred only in the TPN group,…

Surgical Treatment of Obesity

Demographics Obesity has reached epidemic proportions in the United States. The number of obese persons increased by 34% from 2000 to 2016. Nearly 40% of adults and 18% of children are now obese. In Hispanic and black populations, the prevalence is near 50% for adults. Worldwide, the number of overweight people has increased to approximately 38%, with 500 million now obese. Patients with a body mass…

Dietary Fiber

Dietary fiber is the nonstarch polysaccharide part of plant foods that is poorly digested by human enzymes. In the latter half of the 20th century, physicians and scientists began to understand the importance of dietary fiber in maintaining health and dietary fiber deficiencies in causing disease. Cleave first noted the increased sugar intake that resulted from decreased dietary fiber intake. Epidemiologists and gastroenterologists such as Burkett,…

Vascular Disorders of the Liver

Secondary liver disease stemming from vascular pathology related to heart failure, portal vein obstruction, and Budd-Chiari syndrome represents clinically important conditions associated with significant morbidity and impairment of health-related quality of life. The Liver in Heart Failure Heart failure represents one of the more common etiologies for passive congestion of the liver, which may be associated with significant clinical sequelae. Importantly, the severity of passive liver…

Other Infections of the Liver: Amebiasis, Spirochetes, Actinomycosis, Echinococcus, Schistosomiasis

Systemic Amebiasis may be complicated by the development of an amebic liver abscess ( Fig. 179.1 ). Entamoeba histolytica (also known as E. histolytica ) represents the most common parasite identified in amebic liver abscess and is a commensal organism which can result in an invasive amebiasis associated with systemic illness, including fever, nausea, and diarrhea. Symptoms of amebic liver abscess include right upper quadrant pain,…

Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) represents one of the most important and life-threatening complications of chronic liver disease. The 5-year survival of patients with HCC remains sobering despite significant advances in the epidemiology, diagnosis, and management of this disease. The epidemiology of HCC in the United States reveals an ongoing increase in HCC incidence and incidence-based mortality. Although chronic hepatitis B virus (HBV) infection represents the most common…