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The Na+/H+ exchanger isoform NHE2 is highly expressed in the intestinal tract, but its physiological role has remained obscure. The aim of this study was to define its expression, location, and regulatory properties in murine colon and to look for the compensatory changes in NHE2 (−/−) colon that allow normal histology and absorptive function. To this end, we measured murine proximal colonic surface and crypt cell NHE1, NHE2, and NHE3 expression levels, transport rates in response to acid, hyperosmolarity and cAMP in murine proximal colonic crypts, as well as changes in transcript levels and acid-activated NHE activity in NHE2 (−/−) crypts. We found that NHE2 was expressed most abundantly in crypts, NHE1 equally in crypts and surface cells, and NHE3 much stronger in surface cells. NHE2, like NHE1, was activated by low intracellular pH (pHi), hyperosmolarity, and cAMP, whereas NHE3 was activated only by low pHi. Crypts isolated from NHE2 (−/−) mice displayed increased acid-activated NHE1- and NHE3-attributable Na+/H+ exchange activity, no change in NHE1 expression, and NHE3 expression levels twice as high as in normal littermates. No change in cellular ultrastructure was found in NHE2 (−/−) colon. Our results demonstrate high NHE2 expression in the crypts and suggest a role for NHE2 in cryptal pHi and volume homeostasis. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To describe the ultrasound (US) features of reactivation in post-traumatic chronic osteomyelitis in adults. METHODS: Twelve patients with clinical suspicion of reactivation of chronic osteomyelitis, secondary to trauma, surgery, and who were investigated with US were selected for the study. The following US features were assessed: periosseous fluid collection, bone changes (periosteal reactions, cortical irregularity, callus, sequestrum and cloaca) and soft-tissue changes (cellulitis and sinus tracts). US findings were correlated with plain radiography (n = 11), computed tomography (n = 3) and magnetic resonance imaging (n = 2). RESULTS: US detected fluid collections in all patients (12 periosseous and 3 in soft tissues), bone changes in 10 and sinus tracts and cellulitis in 5 patients each. Bone changes detected were cortical irregularity (n = 10), discontinuity of cortex (n = 7), sequestrum (n = 2), callus (n = 2), periosteal reaction (n = 1) and cloaca (n = 1). Cellulitis was seen in 5 patients and sinus tracts in 5. Reactivation was confirmed at surgery in all patients. CONCLUSION: US is a reliable noninvasive imaging modality for the diagnosis of reactivation of post-traumatic chronic osteomyelitis in adults. [ABSTRACT FROM AUTHOR]

Abstract: Aim: This study aimed to explore the molecular mechanisms for the parietal cell loss and fundic hyperplasia observed in gastric mucosa of mice lacking the carbonic anhydrase 9 (CAIX). Methods: We assessed the ability of CAIX‐knockout and WT gastric surface epithelial cells to withstand a luminal acid load by measuring the pHi of exteriorized gastric mucosa in vivo using two‐photon confocal laser scanning microscopy. Cytokines and claudin‐18A2 expression was analysed by RT‐PCR. Results: CAIX‐knockout gastric surface epithelial cells showed significantly faster pHi decline after luminal acid load compared to WT. Increased gastric mucosal IL‐1β and iNOS, but decreased claudin‐18A2 expression (which confer acid resistance) was observed shortly after weaning, prior to the loss of parietal and chief cells. At birth, neither inflammatory cytokines nor claudin‐18 expression were altered between CAIX and WT gastric mucosa. The gradual loss of acid secretory capacity was paralleled by an increase in serum gastrin, IL‐11 and foveolar hyperplasia. Mild chronic proton pump inhibition from the time of weaning did not prevent the claudin‐18 decrease nor the increase in inflammatory markers at 1 month of age, except for IL‐1β. However, the treatment reduced the parietal cell loss in CAIX‐KO mice in the subsequent months. Conclusions: We propose that CAIX converts protons that either backflux or are extruded from the cells rapidly to CO2 and H2O, contributing to tight junction protection and gastric epithelial pHi regulation. Lack of CAIX results in persistent acid backflux via claudin‐18 downregulation, causing loss of parietal cells, hypergastrinaemia and foveolar hyperplasia. [ABSTRACT FROM AUTHOR]

Aim: Slc26a9 is a member of the Slc26 multifunctional anion transporter family. Polymorphisms in Slc26a9 are associated with an increased incidence of meconium ileus and diabetes in cystic fibrosis patients. We investigated the expression of Slc26a9 in the murine pancreatic ducts, islets and parenchyma, and elucidated its role in pancreatic ductal electrolyte and fluid secretion and endocrine function. Methods: Pancreatic Slc26a9 and CFTR mRNA expression, fluid and bicarbonate secretion were assessed in slc26a9−/− mice and their age‐ and sex‐matched wild‐type (wt) littermates. Glucose and insulin tolerance tests were performed. Results: Compared with stomach, the mRNA expression of Slc26a9 was low in pancreatic parenchyma, 20‐fold higher in microdissected pancreatic ducts than parenchyma, and very low in islets. CFTR mRNA was ~10 fold higher than Slc26a9 mRNA expression in each pancreatic cell type. Significantly reduced pancreatic fluid secretory rates and impaired glucose tolerance were observed in female slc26a9−/− mice, whereas alterations in male mice did not reach statistical significance. No significant difference was observed in peripheral insulin resistance in slc26a9−/− compared to sex‐ and aged‐matched wt controls. In contrast, isolated slc26a9−/− islets in short term culture displayed no difference in insulin content, but a significantly reduced glucose‐stimulated insulin secretion compared to age‐ and sex‐matched wt islets, suggesting that the impaired glucose tolerance in the absence of Slc26a9 expression these is a pancreatic defect. Conclusions: Deletion of Slc26a9 is associated with a reduction in pancreatic fluid secretion and impaired glucose tolerance in female mice. The results underline the importance of Slc26a9 in pancreatic physiology. [ABSTRACT FROM AUTHOR]

OBJECTIVE: First, to validate an ultrasonographic measure of the acromio-humeral distance (AHD); second, to compare the AHD variation during active abduction in patients with shoulder impingement syndrome (SIS) and healthy subjects; and third, to evaluate the relationship between functional status and AHD variations before and after rehabilitation in SIS subjects. DESIGN: This study has 3 components: (1) a reliability study, (2) a case-control study, and (3) a preliminary pretreatment/posttreatment clinical trial. SETTING: Primary care hospital setting. PARTICIPANTS: Seven SIS patients and 13 healthy subjects. INTERVENTIONS: For the clinical trial, the SIS subjects participated in 12 sessions of a rehabilitation program over 4 weeks. MAIN OUTCOME MEASURES: First, intraclass correlation coefficient for interobserver reliability; second, AHD measured at 0 degrees, 45 degrees, and 60 degrees of active abduction; and third, Western Ontario Rotator Cuff Index. RESULTS: Intraclass correlation coefficient for interobserver reliability ranged from 0.86 to 0.92 for the 3 shoulder positions. A significant reduction of the AHD was found within groups between rest and active abduction (P < 0.05). Comparison of AHD between groups was not statistically different (P = 0.06; beta < 0.80). In pre-post rehabilitation analysis, improvement of the Western Ontario Rotator Cuff Index score was positively correlated to the reduction of the AHD narrowing as the arm was abducted (r = 0.86; P = 0.01). CONCLUSIONS: The ultrasound measure of AHD is reliable and sensitive. Although a distinct pattern of AHD variation in SIS patients could not be confirmed, a strong positive relationship was found between the reduction of AHD narrowing and functional improvement following rehabilitation. Ultrasound measurement of AHD might help identify SIS patients who will benefit from rehabilitation. [ABSTRACT FROM AUTHOR]

Aim Downregulated in adenoma ( DRA, Slc26a3) is a member of the solute carrier family 26 ( SLC26), family of anion transporters, which is mutated in familial chloride-losing diarrhoea (CLD). Besides Cl−-rich diarrhoea, CLD patients also have a higher-than-average incidence of intestinal inflammation. In a search for potential explanations for this clinical finding, we investigated colonic electrolyte transport, the mucus layer and susceptibility against dextran sodium sulphate ( DSS)-induced colitis in Slc26a3−/− mice. Methods HCO3− secretory (JHCO3−) and fluid absorptive rates were measured by single-pass perfusion in vivo and in isolated mid-distal colonic mucosa in Ussing chambers in vitro. Colonocyte intracellular pH ( pHi) was assessed fluorometrically, the mucus layer by immunohistochemistry and colitis susceptibility by the addition of DSS to the drinking water. Results HCO3− secretory (JHCO3-) and fluid absorptive rates were strongly reduced in Slc26a3−/− mice compared to wild-type (WT) littermates. Despite an increase in sodium/hydrogen exchanger 3 (NHE3) m RNA and protein expression, and intact acid-activation of NHE3, the high colonocyte p H in Slc26a3−/− mice prevented Na+/H+ exchange-mediated fluid absorption in vivo. Mucin 2 (MUC2) immunohistochemistry revealed the absence of a firm mucus layer, implying that alkaline secretion and/or an absorptive flux may be necessary for optimal mucus gel formation. Slc26a3−/− mice were highly susceptible to DSS damage. Conclusions Deletion of DRA results in severely reduced colonic HCO3− secretory rate, a loss of colonic fluid absorption, a lack of a firmly adherent mucus layer and a severely reduced colonic mucosal resistance to DSS damage. These data provide potential pathophysiological explanations for the increased susceptibility of CLD patients to intestinal inflammation. [ABSTRACT FROM AUTHOR]

All segments of the gastrointestinal tract are comprised of an elaborately folded epithelium that expresses a variety of cell types and performs multiple secretory and absorptive functions. While the apical membrane expresses the electrolyte transporters that secrete or absorb electrolytes and water, basolateral transporters regulate the secretory or absorptive rates. During gastric acid formation, Cl/HCO and Na/H exchange and other transporters secure Cl re-supply as well as pH and volume regulation. Gastric surface cells utilize ion transporters to secrete HCO, maintain pH during a luminal acid load and repair damaged surface areas during the process of epithelial restitution. Na/H exchange and Na/HCO cotransport serve basolateral acid/base import for gastroduodenal HCO secretion. The gastric and duodenal epithelium also absorbs salt and water. Recent molecular information on novel ion transporters expressed in the gastric and duodenal epithelium has exploded; however, a function has not been found yet for all transporters. The purpose of this review is to summarize current knowledge on the molecular identity and cellular function of basolateral ion transporters in the gastric and duodenal epithelium. [ABSTRACT FROM AUTHOR]

We investigated the role of the Na+/H+ exchanger regulatory factor 1 (NHERF1) on intestinal salt and water absorption, brush border membrane (BBM) morphology, and on the NHE3 mRNA expression, protein abundance, and transport activity in the murine intestine. NHERF1-deficient mice displayed reduced jejunal fluid absorption in vivo, as well as an attenuated in vitro Na+ absorption in isolated jejunal and colonic, but not of ileal, mucosa. However, cAMP-mediated inhibition of both parameters remained intact. Acid-activated NHE3 transport rate was reduced in surface colonocytes, while its inhibition by cAMP and cGMP was normal. Immunodetection of NHE3 revealed normal NHE3 localization in the BBM of NHERF1 null mice, but NHE3 abundance, as measured by Western blot, was significantly reduced in isolated BBM from the small and large intestines. Furthermore, the microvilli in the proximal colon, but not in the small intestine, were significantly shorter in NHERF1 null mice. Additional knockout of PDZK1 (NHERF3), another member of the NHERF family of adaptor proteins, which binds to both NHE3 and NHERF1, further reduced basal NHE3 activity and caused complete loss of cAMP-mediated NHE3 inhibition. An activator of the exchange protein activated by cAMP (EPAC) had no effect on jejunal fluid absorption in vivo, but slightly inhibited NHE3 activity in surface colonocytes in vitro. In conclusion, NHERF1 has segment-specific effects on intestinal salt absorption, NHE3 transport rates, and NHE3 membrane abundance without affecting mRNA levels. However, unlike PDZK1, NHERF1 is not required for NHE3 regulation by cyclic nucleotides. [ABSTRACT FROM AUTHOR]

Background and aims: We investigated the role of the recently discovered, villous-expressed anion exchanger Slc26a6 (PAT1) and the predominantly crypt-expressed cystic fibrosis transmembrane regulator (CFTR) in basal and acid-stimulated murine duodenal HCO3− secretion in vivo, and the influence of blood HCO3− concentration on both. Methods: The proximal duodenum of anaesthetized mice was perfused in situ, and HCO3− secretion was determined by back-titration. Duodenal mucosal permeability was assessed by determining 51Cr-EDTA leakage from blood to lumen. Results: Compared with wild type (WT) littermates basal duodenal HCO3− secretory rates were slightly reduced in Slc26-deficient mice at low (∼21 mm), and markedly reduced at high blood HCO3− concentration (∼29 mm). In contrast, basal HCO3− secretion was markedly reduced in CFTR-deficient mice compared with WT littermates both at high and low blood HCO3− concentration. A short-term application of luminal acid increased duodenal HCO3− secretory rate in Slc26a6-deficient and WT mice to the same degree, but had no stimulatory effect in the absence of CFTR. Luminal acidification to pH 2.5 did not alter duodenal permeability. Conclusions: The involvement of Slc26a6 in basal HCO3− secretion in murine duodenum in vivo is critically dependent on the systemic acid/base status, and this transporter is not involved in acid-stimulated HCO3− secretion. The presence of CFTR is essential for basal and acid-induced HCO3− secretion irrespective of acid/base status. This suggests a coupled action of Slc26a6 with CFTR for murine basal duodenal HCO3− secretion, but not acid-stimulated secretion, in vivo. [ABSTRACT FROM AUTHOR]

Excitotoxic insults induce c-Jun N-terminal kinase (JNK) activation, which leads to neuronal death and contributes to many neurological conditions such as cerebral ischemia and neurodegenerative disorders. The action of JNK can be inhibited by the D-retro-inverso form of JNK inhibitor peptide (D-JNKI1), which totally prevents death induced by N-methyl-D-aspartate (NMDA) in vitro and strongly protects against different in vivo paradigms of excitotoxicity. To obtain optimal neuroprotection, it is imperative to elucidate the prosurvival action of D-JNKI1 and the death pathways that it inhibits. In cortical neuronal cultures, we first investigate the pathways by which NMDA induces JNK activation and show a rapid and selective phosphorylation of mitogen-activated protein kinase kinase 7 (MKK7), whereas the only other known JNK activator, mitogen-activated protein kinase kinase 4 (MKK4), was unaffected. We then analyze the action of D-JNKI1 on four JNK targets containing a JNK-binding domain: MAPK-activating death domain-containing protein/differentially expressed in normal and neoplastic cells (MADD/DENN), MKK7, MKK4 and JNK-interacting protein-1 (IB1/JIP-1).Cell Death and Differentiation (2007) 14, 240–253. doi:10.1038/sj.cdd.4401988; published online 23 June 2006 [ABSTRACT FROM AUTHOR]

Reduced gastrointestinal HCO[sup -, sub 3] secretion contributes to malabsorption and obstructive syndromes in cystic fibrosis. The apical HCO[sup -, sub 3] transport pathways in these organs have not been defined. We therefore assessed the involvement of apical Cl[sup -]/HCO[sup -, sub 3] exchangers and anion conductances in basal and cAMP-stimulated duodenal HCO[sup -, sub 3] secretion. Muscle-stripped rat and rabbit proximal duodena were mounted in Ussing chambers, and electrical parameters, HCO[sup -, sub 3] secretion rates, and [sup 36]Cl[sup -], [sup 22]Na[sup +], and ³H[sup +] mannitol fluxes were assessed, mRNA expression levels were measured by a quantitative PCR technique. Removal of Cl[sup -] from or addition of 1 mM DIDS to the luminal perfusate markedly decreased basal HCO[sup -, sub 3] secretion but did not influence the HCO[sup -, sub 3] secretory response to 8-bromo-cAMP, which was inhibited by luminal 5-nitro-2-(3-phenylpropylamino)benzoate. Bidirectional [sup 22]Na[sup +] and [sup 36]Cl[sup -] flux measurements demonstrated an inhibition rather than a stimulation of apical anion exchange during cAMP-stimulated HCO[sup -, sub 3] secretion. The ratio of Cl[sup -] to HCO[sup -, sub 3] in the anion secretory response was compatible with both Cl[sup -] and HCO[sup -, sub 3] being secreted via the CFTR anion channel. CFTR expression was very high in the duodenal mucosa of both species. We conclude that in rat and rabbit duodena, an apical Cl[sup -]/HCO[sup -, sub 3] exchanger mediates a significant part of basal HCO[sup -, sub 3] secretion but is not involved in the HCO[sup -, sub 3] secretory response to cAMP analogs. The inhibitor profile, the strong predominance of Cl[sup -] over HCO[sup -, sub 3] in the anion secretory response, and the high duodenal CFTR expression levels suggest that a major portion of cAMP-stimulated duodenal HCO[sup -, sub 3] secretion is directly mediated by CFTR. [ABSTRACT FROM AUTHOR]

Islet-brain1 (IB1) or c-Jun NH2 terminal kinase interacting protein-1 (JIP-1), the product of the MAPK8IP1 gene, functions as a neuronal scaffold protein to allow signalling specificity. IB1/JIP-1 interacts with many cellular components including the reelin receptor ApoER2, the low-density lipoprotein receptor-related protein (LRP), kinesin and the Alzheimer's amyloid precursor protein. Coexpression of IB1/JIP-1 with other components of the c-Jun NH2 terminal-kinase (JNK) pathway activates the JNK activity; conversely, selective disruption of IB1/JIP-1 in mice reduces the stress-induced apoptosis of neuronal cells. We therefore hypothesized that IB1/JIP-1 is a risk factor for Alzheimer's disease (AD). By immunocytochemistry, we first colocalized the presence of IB1/JIP-1 with JNK and phosphorylated tau in neurofibrillary tangles. We next identified a -499A > G polymorphism in the 5' regulatory region of the MAPK8IP1 gene. In two separate French populations the -499A > G polymorphism of MAPK8IP1 was not associated with an increased risk to AD. However, when stratified on the +766C > T polymorphism of exon 3 of the LRP gene, the IB1/JIP-1 polymorphism was strongly associated with AD in subjects bearing the CC genotype in the LRP gene. The functional consequences of the -499A > G polymorphism of MAPK8IP1 was investigated in vitro. In neuronal cells, the G allele increased transcriptional activity and was associated with an enhanced binding activity. Taken together, these data indicate that the increased transcriptional activity in the presence of the G allele of MAPK8IP1 is a risk factor to the onset of in patients bearing the CC genotype of the LRP gene. [ABSTRACT FROM AUTHOR]

Presents a correction to the author's name of the article "Islet-Brain 1/C-Jun N-Terminal Kinase Interacting Protein-1 (IB1/JIP-1) Promoter Variant is Associated With Alzheimer's Disease" that was previously published in the issue of the journal "Molecular Psychiatery" as of November 01, 2003.

Molecular Psychiatry (2003) 8, 363. doi:10.1038/sj.mp.4001342 [ABSTRACT FROM AUTHOR]