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Jin BJ, Thiagarajah JR, Verkman AS. Convective washout reduces the antidiarrheal efficacy of enterocyte surface-targeted antisecretory drugs. ACTA ACUST UNITED AC 2013; 141:261-72. [PMID: 23359285 PMCID: PMC3557305 DOI: 10.1085/jgp.201210885] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Secretory diarrheas such as cholera are a major cause of morbidity and mortality in developing countries. We previously introduced the concept of antisecretory therapy for diarrhea using chloride channel inhibitors targeting the cystic fibrosis transmembrane conductance regulator channel pore on the extracellular surface of enterocytes. However, a concern with this strategy is that rapid fluid secretion could cause convective drug washout that would limit the efficacy of extracellularly targeted inhibitors. Here, we developed a convection-diffusion model of washout in an anatomically accurate three-dimensional model of human intestine comprising cylindrical crypts and villi secreting fluid into a central lumen. Input parameters included initial lumen flow and inhibitor concentration, inhibitor dissociation constant (K(d)), crypt/villus secretion, and inhibitor diffusion. We modeled both membrane-impermeant and permeable inhibitors. The model predicted greatly reduced inhibitor efficacy for high crypt fluid secretion as occurs in cholera. We conclude that the antisecretory efficacy of an orally administered membrane-impermeant, surface-targeted inhibitor requires both (a) high inhibitor affinity (low nanomolar K(d)) to obtain sufficiently high luminal inhibitor concentration (>100-fold K(d)), and (b) sustained high luminal inhibitor concentration or slow inhibitor dissociation compared with oral administration frequency. Efficacy of a surface-targeted permeable inhibitor delivered from the blood requires high inhibitor permeability and blood concentration (relative to K(d)).
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Affiliation(s)
- Byung-Ju Jin
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
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van der Hoeven-Hangoor E, van de Linde I, Paton N, Verstegen M, Hendriks W. Effect of different magnesium sources on digesta and excreta moisture content and production performance in broiler chickens. Poult Sci 2013; 92:382-91. [DOI: 10.3382/ps.2012-02404] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Brock C, Olesen SS, Olesen AE, Frøkjaer JB, Andresen T, Drewes AM. Opioid-induced bowel dysfunction: pathophysiology and management. Drugs 2012; 72:1847-65. [PMID: 22950533 DOI: 10.2165/11634970-000000000-00000] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Opioids are the most commonly prescribed medications to treat severe pain in the Western world. It has been estimated that up to 90% of American patients presenting to specialized pain centres are treated with opioids. Along with their analgesic properties, opioids have the potential to produce substantial side effects, such as nausea, cognitive impairment, addiction and urinary retention. In the gut, opioids exert their action on the enteric nervous system, where they bind to the myenteric and submucosal plexuses, causing dysmotility, decreased fluid secretion and sphincter dysfunction, which all leads to opioid-induced bowel dysfunction (OIBD). In the clinic, this is reported as nausea, vomiting, gastro-oesophageal reflux-related symptoms, constipation, etc. One of the most severe symptoms is constipation, which can be assessed using different scales for subjective assessment. Objective methods such as radiography and colonic transit time can also be used, together with manometry and evaluation of anorectal function to explore the pathophysiology. Dose-limiting adverse symptoms of OIBD can lead to insufficient pain treatment. Even though several treatment strategies are available, the side effects are still a major challenge. Traditional laxatives are normally prescribed but they are often insufficient to alleviate symptoms, especially those from the upper gastrointestinal tract. Newer prokinetics, such as prucalopride and lubiprostone, may be more effective in alleviating OIBD. Another treatment approach is co-administration of opioid antagonists, which either cannot cross the blood-brain barrier or selectively target opioid receptors in the gastrointestinal tract. However, although these new agents have proved to be more efficacious than placebo, clinical trials still need to prove their superiority to standard co-prescribed laxative regimes.
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Affiliation(s)
- Christina Brock
- Mech-Sense, Department of Gastroenterology and Hepatology, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark.
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Medani M, Bzik VA, Rogers A, Collins D, Kennelly R, Winter DC, Brayden DJ, Baird AW. Zinc sulphate attenuates chloride secretion in Human colonic mucosae in vitro. Eur J Pharmacol 2012; 696:166-71. [DOI: 10.1016/j.ejphar.2012.09.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/04/2012] [Accepted: 09/17/2012] [Indexed: 10/27/2022]
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Morrison JD. Prolonged stimulation of pancreatic serous secretions by bile and sodium taurocholate in anaesthetized rats. J Physiol Biochem 2012; 68:503-20. [PMID: 22538870 DOI: 10.1007/s13105-012-0165-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 03/13/2012] [Indexed: 11/27/2022]
Abstract
There have been numerous reports that infusion of either natural bile or bile salts into the duodenum evokes a rapid increase in pancreatic secretion through the release of the hormone secretin from the duodenal mucosa. We have extended this observation by the demonstration of an additional late increase in secretion which persisted for many hours and have sought to identify the processes underlying this increase. In anaesthetised rats, infusion of 20 mM taurocholate into the duodenum caused a staircase-like increase in the weight of pancreatic secretion which extended over many hours during which, the HCO[Formula: see text] and protein output of the secretion showed only minimal changes. This effect was also reproduced with intra-duodenal infusion of natural bile which was inferred to act though its taurocholate content. Since the stimulatory action was also obtained with superfusion of taurocholate or natural bile onto the small intestine and by intravenous injection of taurocholate, it was concluded that taurocholate acted by being absorbed into the bloodstream and then by exerting a stimulatory action on the exocrine pancreas. This action was inhibited by puromycin (a protein synthesis inhibitor), by furosemide (a Na( + )/K( + )/2Cl(-) cotransporter inhibitor), though not by SITS (an inhibitor of Cl(-)/HCO[Formula: see text] exchange). The long lasting increase in pancreatic serous secretion would be consistent with the possible activation of gene transcription by taurocholate leading to increased activity of the Na( + )/K( + )/2Cl(-) cotransporter through which the acinar cells increased their secretions.
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Affiliation(s)
- James D Morrison
- School of Life Sciences, West Medical Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
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Fiskerstrand T, Arshad N, Haukanes BI, Tronstad RR, Pham KDC, Johansson S, Håvik B, Tønder SL, Levy SE, Brackman D, Boman H, Biswas KH, Apold J, Hovdenak N, Visweswariah SS, Knappskog PM. Familial diarrhea syndrome caused by an activating GUCY2C mutation. N Engl J Med 2012; 366:1586-95. [PMID: 22436048 DOI: 10.1056/nejmoa1110132] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Familial diarrhea disorders are, in most cases, severe and caused by recessive mutations. We describe the cause of a novel dominant disease in 32 members of a Norwegian family. The affected members have chronic diarrhea that is of early onset, is relatively mild, and is associated with increased susceptibility to inflammatory bowel disease, small-bowel obstruction, and esophagitis. METHODS We used linkage analysis, based on arrays with single-nucleotide polymorphisms, to identify a candidate region on chromosome 12 and then sequenced GUCY2C, encoding guanylate cyclase C (GC-C), an intestinal receptor for bacterial heat-stable enterotoxins. We performed exome sequencing of the entire candidate region from three affected family members, to exclude the possibility that mutations in genes other than GUCY2C could cause or contribute to susceptibility to the disease. We carried out functional studies of mutant GC-C using HEK293T cells. RESULTS We identified a heterozygous missense mutation (c.2519G→T) in GUCY2C in all affected family members and observed no other rare variants in the exons of genes in the candidate region. Exposure of the mutant receptor to its ligands resulted in markedly increased production of cyclic guanosine monophosphate (cGMP). This may cause hyperactivation of the cystic fibrosis transmembrane regulator (CFTR), leading to increased chloride and water secretion from the enterocytes, and may thus explain the chronic diarrhea in the affected family members. CONCLUSIONS Increased GC-C signaling disturbs normal bowel function and appears to have a proinflammatory effect, either through increased chloride secretion or additional effects of elevated cellular cGMP. Further investigation of the relevance of genetic variants affecting the GC-C-CFTR pathway to conditions such as Crohn's disease is warranted. (Funded by Helse Vest [Western Norway Regional Health Authority] and the Department of Science and Technology, Government of India.).
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Affiliation(s)
- Torunn Fiskerstrand
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, 5021 Bergen, Norway.
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Berend K, van Hulsteijn LH, Gans ROB. Chloride: the queen of electrolytes? Eur J Intern Med 2012; 23:203-11. [PMID: 22385875 DOI: 10.1016/j.ejim.2011.11.013] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 10/20/2011] [Accepted: 11/22/2011] [Indexed: 12/26/2022]
Abstract
BACKGROUND Channelopathies, defined as diseases that are caused by mutations in genes encoding ion channels, are associated with a wide variety of symptoms and have been documented extensively over the past decade. In contrast, despite the important role of chloride in serum, textbooks in general do not allocate chapters exclusively on hypochloremia or hyperchloremia and information on chloride other than channelopathies is scattered in the literature. STUDY DESIGN To systematically review the function of chloride in man, data for this review include searches of MEDLINE, PubMed, and references from relevant articles including the search terms "chloride," "HCl," "chloride channel" "acid-base," "acidosis," "alkalosis," "anion gap" "strong anion gap" "Stewart," "base excess" and "lactate." In addition, internal medicine, critical care, nephrology and gastroenterology textbooks were evaluated on topics pertaining the assessment and management of acid-base disorders, including reference lists from journals or textbooks. CONCLUSION Chloride is, after sodium, the most abundant electrolyte in serum, with a key role in the regulation of body fluids, electrolyte balance, the preservation of electrical neutrality, acid-base status and it is an essential component for the assessment of many pathological conditions. When assessing serum electrolytes, abnormal chloride levels alone usually signify a more serious underlying metabolic disorder, such as metabolic acidosis or alkalosis. Chloride is an important component of diagnostic tests in a wide array of clinical situations. In these cases, chloride can be tested in sweat, serum, urine and feces. Abnormalities in chloride channel expression and function in many organs can cause a range of disorders.
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Affiliation(s)
- Kenrick Berend
- Nephrology department, St. Elisabeth Hospital, Willemstad, Curaçao, The Netherlands.
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Abstract
PURPOSE OF REVIEW To highlight recent developments relating perioperative fluid therapy to gastrointestinal function by reviewing clinically pertinent English language articles mainly from January 2010 to March 2011. RECENT FINDINGS The control of fluid and electrolyte balance involves multiple processes in which the gastrointestinal tract plays an integral role. Diseases affecting the gastrointestinal tract commonly cause fluid and electrolyte disturbance. Similarly, intravenous fluid therapy in the perioperative period can affect gastrointestinal function and have a bearing on postoperative outcome. Striking a balance, in terms of both fluid composition and volume, is likely to reduce the morbidity associated with interstitial edema, a frequently observed occurrence with contemporary perioperative fluid regimens. This balance may be best achieved using individualized and goal-directed approaches to fluid therapy, in order to provide fluid when it is needed and in the correct quantities. SUMMARY In planning strategies of fluid therapy, the possibility of adverse effects on the gastrointestinal tract should be considered, as this is likely to have an impact on fluid and electrolyte balance and postoperative outcome.
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Affiliation(s)
- Abeed H Chowdhury
- Division of Gastrointestinal Surgery, Nottingham Digestive Diseases Centre, NIHR Biomedical Research Unit, Nottingham University Hospitals, Queen's Medical Centre, Nottingham, UK
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Gill M, Bartolo RC, Demmers K, Harfoot N, Fan S, Butt G. The distribution and expression of CFTR restricts electrogenic anion secretion to the ileum of the brushtail possum, Trichosurus vulpecula. ACTA ACUST UNITED AC 2011; 214:1943-54. [PMID: 21562182 DOI: 10.1242/jeb.053371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In eutherian mammals, fluid secretion is essential for intestinal function. This is driven by electrogenic Cl(-) secretion, which involves a NaK2Cl cotransporter (NKCC1) in the enterocyte basolateral membrane and the cystic fibrosis transmembrane conductance regulator (CFTR) in the apical membrane. However, in the possum ileum, NKCC1 expression is low and secretagogues stimulate electrogenic HCO(3)(-) secretion driven by a basolateral NaHCO(3) cotransporter (pNBCe1). Here we investigated whether electrogenic anion secretion occurs in possum duodenum and jejunum and determined the role of CFTR in possum intestinal anion secretion. Prostaglandin E(2) (PGE(2)) and forskolin stimulated a large increase in ileal short-circuit current (I(sc)), consistent with electrogenic HCO(3)(-) secretion, but had little effect on the duodenal and jejunal I(sc). Furthermore, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and N-(2-naphthalenyl)-[(3,5-dibromo-2,4-dihydroxyphenyl)methylene]glycine hydrazide (GlyH101) inhibited cloned possum CFTR in cultured cells and the PGE(2)-stimulated ileal I(sc), implicating CFTR in ileal HCO(3)(-) secretion. Consistent with this, CFTR is expressed in the apical membrane of ileal crypt and lower villous cells, which also express pNBCe1 in the basolateral membrane. In contrast, duodenal and jejunal CFTR expression is low relative to the ileum. Jejunal pNBCe1 expression is also low, whereas duodenal and ileal pNBCe1 expression are comparable. All regions have low NKCC1 expression. These results indicate that cAMP-dependent electrogenic Cl(-) secretion does not occur in the possum small intestine because of the absence of CFTR and NKCC1. Furthermore, CFTR functions as the apical anion conductance associated with HCO(3)(-) secretion and its distribution limits electrogenic HCO(3)(-) secretion to the ileum.
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Affiliation(s)
- Mike Gill
- Department of Physiology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Sainsbury A, Ford AC. Treatment of irritable bowel syndrome: beyond fiber and antispasmodic agents. Therap Adv Gastroenterol 2011; 4:115-27. [PMID: 21694813 PMCID: PMC3105621 DOI: 10.1177/1756283x10387203] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Irritable bowel syndrome (IBS) is a chronic functional disorder of the gastrointestinal tract of unknown etiology. The diagnosis of IBS is made clinically, using symptom-based criteria such as the Manning or Rome criteria. Medical therapy for this condition has traditionally been directed towards symptom relief, using fiber or antispasmodic agents. In recent years, emerging data have confirmed the efficacy of antidepressants, psychological therapies, 5-HT(3) antagonists, 5-HT(4) agonists, and probiotics in the short-term treatment of IBS, although whether these therapies influence the long-term course of the disease is unknown. Increasing knowledge regarding the pathophysiological mechanisms underlying IBS has resulted in a number of novel molecular treatments, which show promise. These include therapies targeting gastrointestinal mucosal chloride channels and guanylate cyclase-C receptors, as well as highly selective agents influencing serotonergic transmission that, at the time of writing, do not appear to have any severe deleterious effects. In this article we provide a summary of current and emerging therapies in this field.
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Affiliation(s)
- Anita Sainsbury
- Leeds Gastroenterology Institute, Leeds General Infirmary, Leeds, UK
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