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Campylobacter jejuni and C. coli are causes of foodborne enteric infection worldwide (1). Campylobacter spp. are among the most frequent pathogens identified in diarrheal samples from persons in Africa, particularly [...]

IntroductionInflammatory bowel diseases (IBD) are chronic recurrent inflammatory diseases of the gastrointestinal tract, mainly Crohn's disease and ulcerative colitis (Scharl and Rogler 2012). The incidence of IBD is increasing each [...], The enterohepatic circulation of bile acids (BAs) critically depends on BA transporters and enzymes, which can be affected by inflammatory bowel disease. Diarrhea in colitis is believed to result in part from BA malabsorption. The work aimed to investigate whether diarrhea in colitis was associated with the expression of BA transporters, enzymes, and nuclear receptors. RT-qPCR and Western blot techniques were used to evaluate the gene and protein levels of Cyp7a1, Asbt, SHP, FXR, Ost[beta] in a 2.4.6- trinitrobenzenesulfonic-acid-induced rat model of colitis. The total BAs (TBAs) levels were assayed using ELISA kits, and the individual BAs were measured by LC-MS/MS. Results showed that the fecal excretions of TBAs were significantly increased by 1.6- fold in acute stage of colitis. In ileum, Asbt was significantly decreased; however, there was a compensatory increase in Cyp7a1 level in liver. Moreover, FXR has a decreased tendency and the downstream target gene SHP was downregulated. Contrary to acute stage, molecular changes were completely reversible during the remission phase. Our results indicated that the expression of Asbt and Cyp7a1 were altered in acute colitis, which performed vital roles in maintaining BA homeostasis. Early medical manipulation of BA transporters and enzymes may help prevent diarrhea.Key words: colitis, bile acid malabsorption, Asbt, Cyp7a1, FXR.Le cycle enterohepatique des acides biliaires (AB) depend de maniere cruciale des transporteurs et des enzymes des AB, lesquels peuvent etre affectes par les maladies inflammatoires du tube digestif. On croit que les diarrhees dans les colites sont en partie le fait d'une malabsorption des AB. Ces travaux visaient a etudier si dans la colite, la diarrhee etait associee a l'expression des transporteurs, des enzymes et des recepteurs nucleaires des AB. A l'aide des techniques de PCR quantitatif par transcriptase inverse et d'immunobuvardage de Western, nous avons evalue les taux des genes et des proteines pour Cyp7a1, Asbt, SHP, FXR et Ost[beta] dans un modele de colite provoquee par l'acide 2,4,6-trinitrobenzenesulfonique chez le rat. Nous avons mesure les taux d'AB totaux (ABT) a l'aide de kits d'ELISA et les taux d'AB individuels a l'aide de la chromatographie liquide couplee a la spectrometrie de masse en tandem (LC-MS/MS). Les resultats ont montre que l'excretion fecale d'ABT augmentait nettement par un facteur de 1,6 pendant les stades aigus de colite. Dans l'ileon, Asbt affichait une nette diminution, mais les taux hepatiques de Cyp7a1 augmentaient de maniere compensatoire. De plus, FXR affichait une tendance a la baisse, et le gene cible SHP en aval etait regule a la baisse. Contrairement a ce que nous observions au stade aigu, les modifications moleculaires etaient entierement reversibles pendant la phase de remission. Nos resultats ont montre que l'expression des genes Asbt et Cyp7a1 etait touchee pendant la colite aigue, alors que leur role est essentiel pour le maintien de l'homeostasie des AB. La manipulation precoce des transporteurs et des enzymes des AB par des moyens medicaux pourrait contribuer a prevenir la diarrhee. [Traduit par la Redaction]Mots-cles: colite, malabsorption des acides biliaires, Asbt, Cyp7a1, FXR.

A case study of a 50-year-old woman with loose bowels is discussed to explain the diagnosis of chronic diarrhea, its causes, symptoms and treatment methodologies. The analysis of case history, physical examination and laboratory tests used to characterize the ailment as VIPoma (vasoactive intestinal polypeptide) amidst several possibilities of causes for the chronic diarrhea are highlighted.

The aim of this study was to characterize in vivo rat colonic motor activity in normal and inflamed states and determine its neural regulation. Circular muscle contractions were recorded by surgically implanted strain-gauge transducers. The rat colon exhibited predominantly giant migrating contractions (GMCs) whose frequency decreased distally. Only a small percentage of these GMCs propagated in the distal direction; the rest occurred randomly. Phasic contractions were present, but their amplitude was very small compared with that of GMCs. Inflammation induced by oral administration of dextran sodium sulfate suppressed the frequency of GMCs in the proximal and middle but not in the distal colon. Frequency of GMCs was suppressed by intraperitoneally administered atropine and 4-diphenylacetoxy-N-methyl-piperidine methiodide and was enhanced by [N.sup.w]-nitro-L-arginine methyl ester. Serotonin, tachykinin, and calcitonin gene-related peptide receptor or receptor subtype antagonists as well as guanethidine and suramin had no significant effect on the frequency of GMCs. Verapamil transiently suppressed the GMCs. In conclusion, unlike the canine and human colons, the rat colon exhibits frequent GMCs and their frequency is suppressed in inflammation. In vivo GMCs are stimulated by neural release of acetylcholine that acts on [M.sub.3] receptors. Constitutive release of nitric oxide may partially suppress their frequency. inflammation; diarrhea; [N.sup.[omega]]-nitro-L-arginine methyl ester; peristaltic reflex; enteric neurons

In inflamed colonic mucosa, the equilibrium between absorptive and secretory functions for electrolyte and salt transport is disturbed. We compared the expression of three major mediators of the intestinal salt transport between healthy and inflamed colonic mucosa to understand the pathophysiology of diarrhea in inflammatory bowel disease. Expression levels of the cystic fibrosis transmembrane regulator (CFTR) ([Cl.sup.-] channel), SLC26A3 ([Cl.sup.-]/HC[O.sup.-.sub.3] exchanger) and SLC9A3 ([Na.sup.+]/[H.sup.+] exchanger) mRNAs were measured by real-time quantitative RT-PCR in peroperative colonic samples from controls (n = 4) and patients with ulcerative colitis (n = 10). Several samples were obtained from each individual. Tissue samples were divided into three subgroups according to their histological degree of inflammation. Expression of CFTR and SLC26A3 proteins were determined by immunohistochemistry and Western blotting from the same samples, respectively. Increased expression of CFTR mRNA was observed in all three groups of affected tissue samples, most pronounced in mildly inflamed colonic mucosa (5-fold increase in expression; P < 0.001). The expression of the CFTR protein was detected from health and inflamed colon tissue. Although the expression of the SLC26A3 mRNA was significantly decreased in severe ulcerative colitis (P < 0.05), the SLC26A3 protein levels remained unchanged in all groups. The expression of SLC9A3 mRNA was significantly changed between the mild and severe groups. Intestinal inflammation modulates the expression of three major mediators of intestinal salt transport and may contribute to diarrhea in ulcerative colitis both by increasing transepithelial [Cl.sup.-] secretion and by inhibiting the epithelial NaCl absorption. inflammation; anion transport; diarrhea; inflammatory bowel disease; cystic fibrosis transmembrane regulator

Ledoussal, Clara, Alison L. Woo, Marian L. Miller, and Gary E. Shull. Loss of the NHE2 [Na.sup.+]/[H.sup.+] exchanger has no apparent effect on diarrheal state of NHE3-deficient mice. Am J Physiol Gastrointest Liver Physiol 281: G1385--G1396, 2001.--The expression of NHE2 and NHE3 on intestinal-brush border membranes suggests that both [Na.sup.+]/[H.sup.+] exchangers serve absorptive functions. Studies with knockout mice showed that the loss of NHE3, but not NHE2, causes diarrhea, demonstrating that NHE3 is the major absorptive exchanger and indicating that any remaining absorptive capacity contributed by NHE2 is not sufficient to compensate fully for the loss of NHE3. To test the hypothesis that NHE2 provides partial compensation for the diarrheal state of NHE3-deficient mice, we crossed doubly heterozygous mice carrying null mutations in the Nhe2 and Nhe3 genes and analyzed the phenotypes of their offspring. The additional loss of NHE2 in NHE3-deficient mice caused no apparent reduction in viability, no further impairment of systemic acid-base status or increase in aldosterone levels, and no apparent worsening of the diarrheal state. These in vivo phenotypic correlates of the absorptive defect suggest that the NaC1, HC[O.sup.-.sub.3], and fluid absorption that is dependent on apical [Na.sup.+]/[H.sup.+] exchange is due overwhelmingly to the activity of NHE3, with little contribution from NHE2. sodium absorption; diarrhea; Slc9a2; Slc9a3 Received 21 June 2001; accepted in final form 14 August 2001

An increase in intestinal permeability in HIV patients with diarrhea increases the absorption of ganciclovir, according to a study of 42 HIV patients. Ganciclovir is used to prevent and treat cytomegalovirus infections.

Congenital chloride diarrhea is a recessively inherited disorder associated with the intestinal electrolyte absorption involving Cl-/HCO-/3 exchange. Caused by mutations in a chromosome 7 gene, the disease has been reported all around the world. The CLD gene supports a transmembrane protein related to the sulfate transporter family supporting three known members in human. Members of the gene family can also effectively transport other anions.

A study was conducted to test whether downregulated in adenoma (DRA) is an intestinal chloride transporter and examine how mutations affect transport. Xenopus oocytes were injected with wild-type and mutagenized DRA cRNA. The uptake of Cl- and So2/4 were assayed before being transported by wild-type DRA. Experimental results indicated that DRA is a chloride transporter defective in chloride diarrhea.

A study was conducted to determine an agent that supports efficacy against in vivo cholera toxin-induced fluid secretion and in vitro cyclic adenylic acid-mediated Cl- secretion. The sealed adult mouse framework was utilized to determine fluid accumulation. Results indicated that the agent supports an inhibitory effect on cAMP-mediated Cl- and fluid secretion. Findings also showed that it can be applied as a broad-spectrum anti-diarrheal agent.

In vitro studies of human distal colon indicated that the tumor necrosis factor-alpha changes Cl- and K+ transport towards secretion. Stimulation of TNF-alpha also caused diarrhea in human immunodeficiency infections and inflammatory bowel diseases (BID). Furthermore, TNF-alpha also increases the levels of prostaglandin E2 which promotes the secretory activity of enterocytes. Treatment with anti-TNF-alpha-antibodies reduced occurrence of diarrhea in BID patients.

This study investigated the effect of clinical and subclinical vitamin A deficiency on intestinal structure and function in rats. Weanling male rats fed a vitamin A-deficient diet (VA-) for 40-42 or 60-63 d were compared with rats either pair-fed (PF) or with free access to the same diet supplemented with vitamin A (VA+). A reference (REF) group was fed a standard rat diet. Weight began to plateau in VA- rats after 42 d, becoming significantly different from PF rats at 60-63 d (P < 0.02). Diarrhea did not develop in any study group. VA- rats had clinical signs of vitamin A deficiency in the 60-63 d study, but not in the 40-42 d study. However, serum and liver retinol concentrations were negligible in all VA- rats. VA- rats in the 60-63 d study had significantly reduced villus height (P < 0.02), and sucrase and maltase activities (P < 0.02) compared with PF rats, There were no differences between VA- and PF rats in mucosal wet weights, protein and DNA concentrations, thymidine kinase activity and glucose transport. No differences were detected in the 40-42 d study for any variable measured. Because clinical vitamin A deficiency in rats causes only mild changes in intestinal structure and function, it is unlikely that these alterations alone are responsible for the interactions observed in epidemiological studies between vitamin A deficiency and diarrheal disease. INDEXING KEY WORDS: vitamin A deficiency; diarrhea; rats; jejunal structure and function

Insulin and IGF-I inhibit calcium-dependent chloride secretion by T84 human colonic epithelial cells. Am J Physiol Gastrointest Liver Physiol 281: G129-G137, 2001.--D-Myo-inositol (3,4,5,6) tetrakisphosphate [Ins(3,4,5,6)[P.sub.4]] or phosphatidylinositol 3-kinase (PI 3-kinase) activity acts to inhibit calcium-dependent chloride secretion in T84 colonic epithelial cells. To further distinguish between the contributions of these two signaling pathways to the inhibition of secretion, we studied effects of insulin, because the insulin receptor links to PI 3-kinase but not to pathways postulated to generate Ins(3,4,5,6)[P.sub.4]. Chloride secretion across T84 cell monolayers was studied in Ussing chambers. Activation of PI 3-kinase was assessed by Western blotting. Basolateral, but not apical, addition of insulin inhibited carbachol- and thapsigargin-induced chloride secretion in a time- and concentration-dependent fashion. Insulin-like growth factor-I (IGF-I) had similar effects. Insulin had no effect on Ins(3,4,5,6)[P.sub.4] levels, and the inhibitory effects of insulin and IGF-I on chloride secretion were fully reversed by the PI 3-kinase inhibitors wortmannin and LY-294002. Western blot analysis showed that both insulin and IGF-I recruited the 85-kDa regulatory and 110-kDa catalytic subunits of PI 3-kinase to anti-phosphotyrosine immunoprecipitates. In conclusion, insulin and IGF-I act to inhibit calcium-dependent chloride secretion through a PI 3-kinase-dependent pathway. Because insulin is released in a pulsatile fashion postprandially and IGF-I levels are elevated in pathological settings, our findings may have physiological and/or pathophysiological significance. insulin-like growth factor I; diarrhea; diabetes

Although chronic diarrhea affects heart function and morphology, the pathogenic mechanisms are unknown. It was our hypothesis that diarrhea imposes metabolic stress to inhibit the synthesis of new contractile proteins. To test this hypothesis, we investigated the effects of lactose-induced diarrhea in rats. The groups were: 1) freely fed controls, 2) rats with lactose-induced diarrhea or 3) pair-fed rats. After 1 wk, hearts from the rats were subjected to subcellular fractionation techniques to isolate the major protein fractions, including myofibrillar proteins. The rates of protein synthesis were measured with concomitant assay of cardiac composition and plasma analytes. In comparison with the control group, diarrhea induced the following changes (P [is less than] 0.05): a decrease in heart Weight, reduced RNA and mixed protein contents and a reduction in the fractional rate of mixed protein synthesis. There was a reduction in the content of all protein fractions. The fractional synthesis rate was reduced only for the myofibrillar fraction. Plasma insulin-like growth factor-I, but not corticosterone, was reduced. Plasma cholesterol and triglyceride concentrations were also reduced. In comparison with the pair-fed group, diarrhea induced the following changes (P [is less than] 0.05): a reduction in heart weight and fractional rate of mixed protein synthesis, reduced myofibrillar absolute synthesis rate and increased sarcoplasmic/myofibrillar fractional synthesis rate ratio. Plasma bicarbonate, triglyceride and urea concentrations were reduced, with an increase in albumin. Diarrhea impaired cardiac biochemistry, including a reduction in protein content and synthesis. A substantial proportion of these changes is due to anorexia, but the selective reduction in the synthesis of contractile proteins is a feature exclusive to the diarrhea group and may be due to reductions in plasma insulin-like growth factor-I. J. Nutr. 131: 1513-1519, 2001. KEY WORDS: * diarrhea * heart * protein synthesis * rats insulin-like growth factor

IFN-[Gamma] downregulates expression of [Na.sup.+]/[H.sup.+] exchangers NHE2 and NHE3 in rat intestine and human Caco2/bbe cells. Am J Physiol Cell Physiol 280: C1224-C1232, 2001.--Diarrhea associated with inflammatory bowel diseases has traditionally been attributed to stimulated secretion. The purpose of this study was to determine whether chronic stimulation of intestinal mucosa by interferon-[Gamma] (IFN-[Gamma]) affects expression and function of the apical membrane [Na.sup.+]/[H.sup.+] exchangers NHE2 and NHE3 in rat intestine and Caco-2/bbe (C2) cells. Confluent C2 cells expressing NHE2 and NHE3 were treated with IFN-[Gamma] for 2, 24, and 48 h. Adult rats were injected with IFN-[Gamma] intraperitoneally for 12 and 48 h. NHE2 and NHE3 activities were measured by unidirectional [sup.22]Na influx across C2 cells and in rat brush-border membrane vesicles. NHE protein and mRNA were assessed by Western and Northern blotting. IFN-[Gamma] treatment of C2 monolayers caused a [is greater than] 50% reduction in NHE2 and NHE3 activities and protein expression. In rats, region-specific, time- and dose-dependent reductions of NHE2 and NHE3 activities, protein expression, and mRNA were observed after exposure to IFN-[Gamma]. Chronic exposure of intestinal epithelial cells to IFN-[Gamma] results in selective downregulation of NHE2 and NHE3 expression and activity, a potential cause of inflammation-associated diarrhea. inflammatory bowel disease; inflammation; mucosa; sodium transport; sodium absorption; water and electrolyte transport; diarrhea; malabsorption; transporter; intestinal adaptation

The authors had observed that during episodes of diarrhea caused by Clostridium dificile, the body tends to develop an antibody response to toxin A. The current investigation demonstrated that these antibodies, formed during the first bout with the pathogen, tend to protect the patient against recurrence of the diarrhea.

Oprins, Judith C. J., Helen P. Meijer, and Jack A. Groot. TNF-[Alpha] potentiates the ion secretion induced by muscarinic receptor activation in HT29cl.19A cells. Am. J. Physiol. Cell Physiol. 278: C463-C472, 2000.--Chronic gastrointestinal diseases such as ulcerative colitis and Crohn's disease are characterized by severe diarrhea. Mucosal biopsies of these patients show enhanced levels of cytokines, secreted by infiltrated inflammatory cells. In this study, we investigated the effect of the cytokine tumor necrosis factor-[Alpha] (TNF-[Alpha]) on ion secretion in human intestinal epithelial cells. The conventional microelectrode technique in the cell line HT29cl.19A was used, which allows for simultaneous measurements of transepithelial potential difference and intracellular potential difference across the apical membrane. Preincubation (2-78 h) with 10 ng/ml TNF-[Alpha] did not change basal secretory activity. However, the secretory response to the muscarinic receptor agonist carbachol was strongly increased after exposure to TNF-[Alpha] Application of the protein kinase C (PKC) inhibitor GF 109203X (bisindolylmaleimide I) inhibited the response to carbachol as well as the TNF-[Alpha] potentiated response, indicating that PKC mediates the effect of carbachol in this cell line. Propranolol, a substance that inhibits the phospholipase D (PLD) pathway, strongly reduced the response to muscarinic stimulation and its potentiation by TNF-[Alpha]. The results indicate that activation of PLD is involved in ion secretion induced by muscarinic receptor activation and that TNF-[Alpha] can potentiate this pathway. phospholipase D; protein kinase C; intestinal epithelia; carbachol; cytokine; tumor necrosis factor-[Alpha]

One function of N-linked glycans is to assist in the folding of glycoproteins by mediating interactions of the lectin-like chaperone proteins calnexin and calreticulin with nascent glycoproteins. These interactions can be prevented by inhibitors of the [Alpha]-glucosidases, such as N-butyl-deoxynojirimycin (NB-DNJ) and N-nonyl-DNJ (NN-DNJ), and this causes some proteins to be misfolded and retained within the endoplasmic reticulum (ER). We have shown previously that the NN-DNJ-induced misfolding of one of the hepatitis B virus (HBV) envelope glycoproteins prevents the formation and secretion of virus in vitro and that this inhibitor alters glycosylation and reduces the viral levels in an animal model of chronic HBV infection. This led us to investigate the effect of glucosidase inhibitors on another ER-budding virus, bovine viral diarrhea virus, a tissue culture surrogate of human hepatitis C virus (HCV). Here we show that in MDBK cells [Alpha]-glucosidase inhibitors prevented the formation and secretion of infectious bovine viral diarrhea virus. Data also are presented showing that NN-DNJ, compared with NB-DNJ, exhibits a prolonged retention in liver in vivo. Because viral secretion is selectively hypersensitive to glucosidase inhibition relative to the secretion of cellular proteins, the possibility that glucosidase inhibitors could be used as broad-based antiviral hepatitis agents is discussed. A single drug against HBV, HCV, and, possibly, HDV, which together chronically infect more than 400 million people worldwide, would be of great therapeutic value.

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhea in humans. The mouse homolog of EPEC, Citrobacter rodentium, causes colonic hyperplasia in young mice. EPEC and C. rodentium [...], Enteropathogenic Escherichia coli (EPEC) cells adhere to gut epithelial cells through intimin [Alpha]: the ligand for a bacterially derived epithelial transmembrane protein called the translocated intimin receptor. Citrobacter rodentium colonizes the mouse colon in a similar fashion and uses a different intimin: intimin Β. Intimin [Alpha] was found to costimulate submitogenic signals through the T cell receptor. Dead intimin [Β.sup.+] C. rodentium, intimin [Alpha]-transfected C. rodentium or E. coli strain K12, and EPEC induced mucosal hyperplasia identical to that caused by C. rodentium Eve infection, as well as a massive T helper cell-type 1 immune response in the colonic mucosa. Mutation of cysteine-937 of intimin to alanine reduced costimulatory activity in vitro and prevented immunopathotogy in vivo. The mucosal changes elicited by C. rodentium were interferon-[Gamma]-dependent. Immunopathology induced by intimin enables the bacteria to promote conditions that are favorable for increased microbial colonization.