bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carcinoid syndrome
Authors: Khoo B. , Tan T.M. , Bloom S.R. 
Published: February 2020

Abstract
Carcinoid syndrome is a paraneoplastic syndrome caused by the release of 5-hydroxytryptamine (5-HT or serotonin) and other vasoactive substances from neuroendocrine tumours (NETs), typically those arising from the duodenum, jejunum, ileum, and also from bronchial NETs. Characteristic clinical features, which typically arise when tumours have metastasized to the liver, are flushing and secretory diarrhoea, and occasionally wheezing. Carcinoid crisis is an acute and life-threatening manifestation with sustained flushing, hyperdynamic shock, and acute kidney injury. Carcinoid heart disease typically manifests in the right side of the heart with valvular insufficiency and heart failure. Diagnosis is made by a combination of the characteristic clinical syndrome, biochemical markers such as 5-hydroxyindoleacetic acid (a metabolite of 5-HT), histopathological examination of tissue from tumour deposits, and imaging with conventional cross-sectional modalities as well as somatostatin receptor scintigraphy. Treatment is most often directed at control of symptoms, with the standard of care for control of the carcinoid syndrome being a somatostatin analogue. Symptomatic therapies are used to palliate diarrhoea. Niacin supplements should be given to forestall the development of pellagra. Multiple modalities for treatment of NETs exist, which should be directed by a multidisciplinary team. Their general prognosis is good with median overall survival of 9.3 years, but the presence of carcinoid syndrome cuts this to 5.0 years, and less in the presence of heart disease.
Differential diagnosis and investigation of malabsorption
Authors: Forbes Alastair , Mulcahy Victoria 
Published: February 2020

Abstract
Malabsorption is defined as defective mucosal absorption in the intestine, with clinical presentation ranging from diarrhoea or steatorrhoea with massive weight loss, through to abdominal bloating, fatigue, changes in bowel habit, or anaemia. There are many causes, but the commonest in adult life are coeliac disease, Crohn’s disease, and bile salt malabsorption. Simple blood tests may prompt suspicion of malabsorption, will sometimes go a long way to providing a diagnosis, and will guide further investigation with specific tests, for example, serum antibody to tissue transglutaminase (coeliac disease), endoscopic examinations, imaging studies, breath tests, and tests of bile salt absorption. Treatment for malabsorption is directed (where possible) to the underlying cause as specific agents to address the malabsorption itself are lacking. General nutritional support and replacement of individual deficiencies are crucial.
Coeliac disease
Authors: Mooney Peter D. , Sanders David S. 
Published: February 2020

Abstract
Coeliac disease is a common disorder of the small intestine in which storage proteins in dietary wheat, rye, and barley (gliadin, secalins, and hordeins, usually referred to as ‘gluten’) induce an autoimmune enteropathy characterized by villous atrophy in genetically susceptible individuals. The prevalence of coeliac disease is 0.2 to 2% in populations with high consumption of gluten-containing foods. Females are more commonly affected than males (1.5–2:1), with typical presentation now in the forties. ‘Classical’ coeliac disease presented in childhood with malabsorption, but this is now rare. ‘Nonclassical’ presentations are now the norm, and highly variable, ranging from nonspecific abdominal symptoms to the consequences of malabsorption (e.g. anaemia, osteoporosis) to nongastrointestinal symptoms (e.g. ataxia, dermatitis herpetiformis), and many have no symptoms at all. Diagnosis is made by serological testing for (usually) antitissue transglutaminase antibodies, which have excellent sensitivity and specificity, with confirmation by duodenal biopsy. Treatment is with a gluten-free diet, which constitutes a major challenge for some people. Most patients (but not all) can eat pure oats. Complications include lymphoma, osteoporosis, and other autoimmune conditions. Patients have a normal life expectancy, although quality of life is adversely affected.
Effects of massive bowel resection
Authors: Middleton Stephen J. , Gabe Simon M. , Playford Raymond J. 
Published: February 2020

Abstract
Major vascular events involving the superior mesenteric artery and small-bowel volvulus are the commonest reasons for adults to require massive intestinal resection. The ability of the residual bowel to adapt after resection varies greatly between patients, but common postoperative problems include sepsis, diarrhoea (or high-output stoma losses), fluid and electrolyte imbalance, malnourishment (protein–energy malnutrition, mineral and vitamin deficiencies), gallstones, renal stones, and psychological illness. Where appropriate, oral nutrition, initially consisting of low-volume polymeric feeds administered by nasogastric or enteral tube, should be started within the first few days of surgery. Small-volume, frequent, solid or semisolid meals with low long-chain triglycerides and (when colon is in continuity) oxalate content should be introduced subsequently, and isotonic electrolyte solutions given as required. Oral multivitamin and mineral supplements are usually needed, and vitamin B12 injections may be required. There should be regular long-term monitoring of fat-soluble vitamins (A and D), vitamin B12, folate, magnesium, zinc, and bone status. Long-term intravenous nutrition is sometimes needed. Growth factor administration, especially glucagon-like peptide-2 analogues, may stimulate bowel adaptation. Small-bowel lengthening may be considered for patients with dilated bowel close to the length required. Those who are dependent on peripheral nutrition and develop complications such as loss of venous access or liver disease should be considered for intestinal transplantation.
Irritable bowel syndrome
Authors: Farmer Adam D. , Aziz Qasim 
Published: February 2020

Abstract
Symptoms suggestive of disturbed lower gastrointestinal function without adequate explanation are very common in adults in the Western world, up to 15% of whom experience such symptoms at any one time, although most do not seek medical advice. The currently used terms are best viewed as an attempt to provide some clinically useful, rather than pathophysiologically accurate, categorization of patients and their symptoms based on disordered gut–brain interactions. Irritable bowel syndrome is defined according to the Rome III criteria as recurrent abdominal pain or discomfort associated with a change in bowel habit for at least 6 months, with symptoms experienced on at least 3 days of at least 3 months. Many subtypes are recognized. Routine haematological and biochemical screening is usually performed on the assumption that it will be normal. Features that raise the suspicion of organic disease and indicate a need for further investigation include the onset of symptoms in middle-aged or older individuals, weight loss, or blood in the stool. Management remains empirical: no single pharmacological agent or group of agents has ever been found to be consistently effective. The principal task of the physician is to provide explanation and reassurance (sometimes supplemented by psychological treatments), but particular symptoms are often treated as follows: (1) constipation—defecation may be eased by supplementary dietary fibre and poorly absorbed fermentable carbohydrates which increase faecal bulk and soften the stool; osmotic laxatives and enemas are used for the severely constipated patient, as well as more novel agents; (2) diarrhoea—attention to diet is often helpful, as are simple antidiarrhoeal agents; and (3) abdominal pain—antispasmodics (e.g. hyoscine butyl bromide) are frequently used, as are antidepressants.
Colonic diverticular disease
Authors: Buchs Nicolas C. , Hompes Roel , Ashraf Shazad Q. , Mortensen Neil J.McC. 
Published: February 2020

Abstract
Colonic diverticula are herniations of mucosa through the bowel musculature. They are seen most often in the sigmoid and descending colon, with a prevalence of up to 65% in people over the age of 80 in European populations. They are uncommon in African and Asian countries, where the prevalence is only 0.2%. A lifelong diet deficient in dietary fibre is associated with their development, but it is not known why some diverticula become symptomatic. Diverticula are usually discovered incidentally, but symptoms which are attributable to diverticular disease include colicky abdominal pain and bloating, often accompanied by a change in bowel habit with the passage of broken, pellety stools after considerable straining. All patients with such presentation should be investigated to exclude rectal or sigmoid carcinoma. Treatment is with reassurance that there is no serious underlying disease, a high-fibre diet, and—for patients with pain—antispasmodics such as mebeverine. Elective resection may be indicated in the few patients who have repeated severe attacks. Complications of diverticular disease include diverticulitis, pericolic abscess formation, peritonitis, intestinal obstruction, haemorrhage, and fistula formation. Acute diverticulitis typically presents with pain and tenderness over the left lower abdomen, and the patient may have pyrexia, malaise, anorexia, and nausea. Treatment is with rest, broad-spectrum antibiotics, and analgesia. Resection of the sigmoid colon may be necessary if symptoms fail to resolve or recur, or for patients with complications (peritonitis, fistula, obstruction). Overall, percutaneous drainage, antibiotic treatment, and expectant policies have reduced the need for both acute and elective surgical treatment.
Congenital abnormalities of the gastrointestinal tract
Authors: Uhlig Holm H. 
Published: February 2020

Abstract
Congenital abnormalities of the gastrointestinal tract can be divided into macroscopic anatomical abnormalities and monogenically determined, high-penetrance functional defects that present either directly postnatally or during the first few months of life. On occasion, symptoms may be delayed for months or years even in patients with substantial anatomical defects. Anatomical and structural abnormalities can affect any part of the gut. These include oesophageal atresia and tracheo-oesophageal fistula, anterior abdominal wall defects, congenital pyloric stenosis, atresia and stenosis of the small intestine, duplication of the gastrointestinal tract, small intestinal malrotation with or without volvulus, small intestinal lymphangiectasia, Meckel’s diverticulum, congenital short intestine syndrome, colonic atresia, Hirschsprung’s disease, and imperforate anus. Meconium ileus is an intestinal obstruction that develops in utero, often associated with subsequent structural abnormalities. The widespread use of ultrasonography allows many abnormalities to be recognized prenatally. Presentation of structural congenital abnormalities of the gastrointestinal tract in adult life is uncommon, but small intestinal lymphangiectasia, Meckel’s diverticulum, or small intestinal obstruction can present beyond childhood. Functional congenital abnormalities include multiple genetic defects that cause congenital diarrhoea due to malabsorption and maldigestion, defects in enterocyte and enterochromaffin cell development, and autoimmune enteropathies. In addition, there is a group of genetic defects that predispose to development of extreme early infantile onset of inflammatory bowel disease. An interdisciplinary approach is required for the optimal management of children with complex congenital abnormalities.
Cancers of the gastrointestinal tract
Authors: Labib Peter L. , Bridgewater J.A. , Pereira Stephen P. 
Published: February 2020

Abstract
Cancers of the gastrointestinal tract are one of the most rewarding interfaces in translational medicine, leading to greater understanding of the genetic mechanisms leading to cancer and the development of novel targeted therapies. Diagnosis of gastrointestinal tract cancers is usually made or suspected at endoscopy and confirmed by biopsy. Oesophageal cancer is a common cancer, usually of squamous cell histology, that is particularly prevalent in East Asia and Southeast Africa. Typical presentation is with dysphagia. Overall survival at 5 years is 15%. Usually adenocarcinoma, stomach cancer is particularly prevalent in East Asia, Eastern Europe, and Western South America. Predisposing factors include Helicobacter pylori infection, low socioeconomic status, tobacco smoking, heavy alcohol use, and diet. Dysphagia, early satiety, and anaemia are common presenting features, with weight loss being an indication of advanced disease. Overall survival at 5 years is 18.9%. Colorectal cancer is the third most common cancer in men and second most common in women worldwide, and is predisposed to by a Western diet. Most cases arise by transformation of an adenoma to a carcinoma by sequential inherited and acquired mutations. Typical presentations of left-sided tumours are alteration in bowel habit, obstruction, or overt bleeding, whereas right-sided tumours often present with iron-deficiency anaemia. Overall survival at 5 years is now almost 60%.
Vascular disorders of the gastrointestinal tract
Authors: Boyapati Ray 
Published: February 2020

Abstract
A wide range of vascular disorders and vasculitides may affect the gastrointestinal tract. Most are quite uncommon, but presentations are often dramatic with intestinal bleeding or gangrene. Intestinal ischaemia is most commonly due to atherosclerosis or thrombosis causing arterial or venous mesenteric vascular occlusion. There are four primary syndromes. (1) Ischaemic colitis—presents with abdominal pain, nausea, vomiting, and tenderness followed by passage of loose bloody stool. Supportive management is usually sufficient, but a key challenge is early identification of patients with severe injury who are likely to progress to transmural ulceration and perforation. (2) Acute mesenteric ischaemia—typically presents with sudden abdominal pain, initially without localizing signs such that diagnosis is often delayed. Priorities of management are resuscitation, exclusion of other causes of apparent abdominal catastrophe, and prompt laparotomy to resect ischaemic bowel. (3) Chronic mesenteric ischaemia—most often caused by atherosclerotic disease and presents with severe and poorly localized cramping abdominal pain after eating. Diagnosis requires evidence of vascular occlusion on imaging, and revascularization is the definitive management strategy. (4) Mesenteric venous thrombosis—diagnosis is most commonly via cross-sectional imaging. The mainstay of treatment is supportive, as well as anticoagulation and a search for predisposing factors. Vasculitides affecting the intestine may be primary or secondary. Abdominal symptoms rarely dominate the clinical picture. Vascular lesions of the gastrointestinal tract may present with acute haemorrhage, chronic iron deficiency anaemia, or obstruction. Lesions include angiodysplasias, telangiectasias, haemangiomas, Dieulafoy lesions, and gastric antral vascular ectasia. These lesions may occur in isolation or as part of a syndrome (e.g. hereditary haemorrhagic telangiectasia).
Pathobiology of chronic liver disease
Authors: Mehal Wajahat Z. 
Published: February 2020

Abstract
Chronic liver disease is responsible for most of the clinical burden of liver disease. Chronic liver injury can occur via a variety of mechanisms, including sterile inflammation and activation of innate and adaptive immunity. Despite the diversity of disease aetiologies and the ability of the liver to regenerate, a significant minority of patients with chronic liver disease proceed to liver fibrosis and eventually cirrhosis, which is defined histologically by regenerative hepatocyte nodules surrounded by fibrous bands of matrix. Ongoing liver injury stimulates the development of a myofibroblast cell type which is responsible for matrix remodelling, haemodynamic changes, and immune cell regulation. This typically results in repair without significant modification of the basic liver structure. In a few subjects, this repair process results in alterations of the basic structure of the liver with loss of hepatocyte mass, deposition of collagen, and the development of hypertension in the portal venous system. Although cirrhosis is well defined histologically, there is a spectrum of severity. In early cirrhosis, patients are asymptomatic but with increasing derangement in hepatic function and portal hypertension, patients can decompensate and develop ascites, coagulopathy, encephalopathy, jaundice, renal failure, oesophageal varices, and spontaneous bacterial infections. Management is focused on removing or reducing ongoing liver injury, and managing cirrhosis-related complications by the use of low-salt diets, diuretics, β-blockers, endoscopic therapy, vasopressors, and antibiotics. There is, as yet, no definite role for antifibrotic medications.
Liver failure
Authors: Macnaughtan Jane , Jalan Rajiv 
Published: February 2020

Abstract
Liver failure occurs when loss of hepatic parenchymal function exceeds the capacity of hepatocytes to regenerate or repair liver injury. Acute liver failure is characterized by jaundice and prolongation of the prothrombin time in the context of recent acute liver injury, with hepatic encephalopathy occurring within 8 weeks of the first onset of liver disease. Acute-on-chronic liver failure is characterized by hepatic and/or extrahepatic organ failure in patients with cirrhosis associated with an identified or unidentified precipitating event. The commonest causes of acute liver failure are acute viral hepatitis and drugs. Acute-on-chronic liver failure is most commonly precipitated by infection, alcohol abuse, and superimposed viral infection. The main clinical manifestations are hepatic encephalopathy, coagulopathy, jaundice, renal dysfunction, and haemodynamic instability. Infection and systemic inflammation contribute to pathogenesis and critically contribute to prognosis. Specific therapy for the underlying liver disease is administered when available, but this is not possible for most causes of liver failure. Treatment is predominantly supportive, with particular emphasis on (1) correction or removal of precipitating factors; (2) if encephalopathy is present, using phosphate enemata, nonhydrolysed disaccharide laxatives, and/or rifaximin; (3) early detection and prompt treatment of complications such as hypoglycaemia, hypokalaemia, cerebral oedema, infection, and bleeding. The onset of organ failure should prompt discussion with a liver transplantation centre. The mortality of acute liver failure (without liver transplantation) is about 40%. Patients with acute liver failure who do not develop encephalopathy can be expected to recover completely. Those who recover from an episode of acute-on-chronic liver failure should be considered for liver transplantation because otherwise their subsequent mortality remains high.
Hepatitis A to E
Authors: Alexander Graeme J.M. , Nash Kate 
Published: February 2020

Abstract
The clinical picture with each of the five major hepatitis viruses A, B, C, D, and E depends firstly upon whether infection is acute, with resolution, or evolves into chronic infection; secondly, on the grade of hepatic inflammation; and thirdly, the stage of fibrosis. Acute icteric hepatitis is the most easily recognized consequence of infection and is generally a self-limited condition. In otherwise healthy individuals, only hepatitis B and C cause chronic viral hepatitis. In immunosuppressed individuals, hepatitis A can follow a protracted course, while hepatitis E can evolve to chronic infection. A specific diagnosis is made by the combination of serology and polymerase chain reaction. Uncomplicated cases recover spontaneously; there is no proven therapy to enhance recovery. Acute liver failure caused by viral hepatitis now has a good outcome, with liver transplantation available for those with poor parameters at onset. Protection against hepatitis A and B is available, both by active vaccination and (less often now) by passive administration of hepatitis B immunoglobulin preparations. Vaccines for hepatitis C are some distance away, but for hepatitis E are under investigation. Vaccination against hepatitis B also protects against hepatitis D.
Primary sclerosing cholangitis
Authors: Lynch Kate D. , Chapman Roger W. 
Published: February 2020

Abstract
Primary sclerosing cholangitis is a chronic cholestatic liver disease caused by diffuse inflammation and fibrosis that can involve the entire biliary tree. The cause is unknown, but it is presumed to be immune mediated, and there is a close association with inflammatory bowel disease, particularly ulcerative colitis. The disorder tends to affect men (male:female, 2:1), some presenting with fatigue, intermittent jaundice, weight loss, right upper quadrant pain, and pruritus, but many are asymptomatic at diagnosis, which is made incidentally when a persistently raised serum alkaline phosphatase is discovered, usually in the clinical setting of ulcerative colitis. Serum biochemical tests usually indicate cholestasis, but diagnosis is based on three criteria: (1) generalized beading and stenosis of the biliary system on cholangiography; (2) absence of choledocholithiasis or a history of bile duct surgery; and (3) exclusion of bile duct cancer, usually by prolonged follow-up. There is no curative medical treatment. Pruritus is initially managed with cholestyramine, with second-line treatments including rifampicin and naltrexone. Orthotopic liver transplantation is the only option available for young patients with advanced liver disease.
Tumours of the pancreas
Authors: Skipworth James R.A. , Pereira Stephen P. 
Published: February 2020

Abstract
Pancreatic cancer, most commonly in the form of a solid ductal adenocarcinoma, accounts for 3% of all cancers but ranks in the top five leading causes of cancer deaths in most developed countries, reflecting the fact that it has a very poor prognosis (median survival 6–9 months). It is a disease of older age (85% of patients &gt;65 years), and commoner in smokers.
Most patients present with locally advanced or metastatic disease, often with obstructive jaundice. Pain is unusual in early disease, but when present is characteristically described as ‘gnawing’, ever present, and frequently radiating into the back. Weight loss is commonly due to anorexia as a result of jaundice or pain, but can occasionally be the only presenting symptom.
Serum biochemistry will typically show elevated bilirubin and a cholestatic picture of liver enzymes, with particular elevation of alkaline phosphatase and γ-glutamyl transferase. Transabdominal ultrasonography is usually the primary investigation in a patient with jaundice and can detect pancreatic tumours greater than 2 cm in size or hepatic metastases with a diagnostic accuracy of 75%, but identifies smaller tumours much less reliably. The essential investigations for the diagnosis and staging of pancreatic cancer are contrast-phased CT scan and occasionally MRI.
The only curative treatment for pancreatic cancer is surgical excision. This is technically feasible in up to 20% patients at presentation, but even after careful selection almost 40% of these will have positive microscopic resection margins, and overall postoperative survival is only around 10% at 5 years, the remainder experiencing metastatic disease in the peritoneum, liver, or lungs. Adjuvant chemotherapy with gemcitabine can double the 5-year survival rate. Palliative management may require biliary stenting for jaundice, duodenal stenting (or surgical bypass) for gastric outlet obstruction, pain control, and palliative chemotherapy.