| 1. |
- Henriksnäs, Johanna, et al.
(författare)
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Acute effects of Helicobacter pylori extracts on gastric mucosal blood flow in the mouse
- 2009
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Ingår i: World Journal of Gastroenterology. - : Baishideng Publishing Group Inc.. - 1007-9327 .- 2219-2840. ; 15:2, s. 219-225
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To investigate the mechanisms underlying the reduction in gastric blood flow induced by a luminal water extract of Helicobacter pylori (HPE).METHODS: The stomachs of isoflurane-anesthetized mice were exteriorized, and the mucosal surface exposed. Blood flow was measured with the laser-Doppler technique, and systemic arterial blood pressure monitored. C57BL/6 mice were exposed to water extract produced from H pylori strain 88-23. To investigate the role of a nerve- or iNOS-mediated pathway, we used intraluminal lidocaine and iNOS-/- mice. Blood flow response to the endogenous nitric oxide synthase inhibitor asymmetric dimethyl arginine (ADMA) was also assessed.RESULTS: In wild-type mice, HPE decreased mucosal blood flow by approximately 30%. This reduction was abolished in iNOS-deficient mice, and by pre-treatment with lidocaine. Luminally applied ADMA resulted in reduction in blood flow similar to that observed in wild-type mice exposed to HPE.CONCLUSION: A H pylori water extract reduces gastric mucosal blood flow acutely through iNOS- and nerve-mediated pathways.
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| 2. |
- Henriksnäs, Johanna, et al.
(författare)
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An in vivo model for gastric physiological and pathophysiological studies in the mouse
- 2005
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 184:2, s. 151-159
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Tidskriftsartikel (refereegranskat)abstract
- Aim: In vivo models for studying gastrointestinal physiology and pathophysiology are well established in rats. Since a number of genetically modified mice are available there is a need for reliable mouse models. The aim of this project was to develop an in vivo mouse model for gastrointestinal studies. Methods: C57bl/6, NMRI and transgenic FVB/N (expressing human α-1,3/4-fucosyltransferase) mice were anaesthetized with isoflurane and the gastric mucosa exteriorized for intravital microscopy. Acid–base status and acid secretion were measured and blood pressure was continuously monitored. Gastric mucosal blood flow was recorded by laser-Doppler flowmetry. Mucus thickness and accumulation rate were measured with micropipettes. Results: We have developed an in vivo mouse model for studies of the gastric mucosa. With isoflurane anaesthesia the preparation can be studied for up to 5 h with stable blood pressure and mucosal blood flow. Acid–base status agrees with results from other laboratories. Blood flow increased in both C57bl/6 and α1.3/4-FT mice in response to luminal HCl, and the mucus gel could be divided into a firmly and a loosely adherent layer, all comparable with results in the rat. However, the firmly adherent mucus layer was thinner (45 ± 2 μm), and the mucus accumulation rate lower, than in the rat. Furthermore, both basal and stimulated acid secretion showed lower outputs than in the rat. Conclusions: This model has great potential for investigations of gastrointestinal physiology and pathophysiology and can be applied for Helicobacter pylori infection studies.
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| 3. |
- Henriksnäs, Johanna, 1973-
(författare)
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Helicobacter pylori and Gastric Protection Mechanisms : An in vivo Study in Mice and Rats
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The stomach is frequently exposed to hazardous agents and to resist this harsh environment, several protective mechanisms exist. Of special interest is the gastric pathogen Helicobacter pylori which causes gastritis, ulcers and cancer but the mechanism leading to these diseases are still unclear. However it is very likely that H. pylori negatively influence the protection mechanisms that exist in the stomach. The aims of the present investigation were first to develop an in vivo mouse model in which different protection mechanisms could be studied, and second to investigate the influence of H. pylori on these mechanisms. An in vivo preparation of the gastric mucosa in mice was developed. This preparation allows studies of different gastric mucosal variables and can also be applied for studies in other gastro-intestinal organs. Mice chronically infected with H. pylori, were shown to have a reduced ability of the mucosa to maintain a neutral pH at the epithelial cell surface. This could be due to the thinner inner, firmly adherent mucus gel layer, and/or to defective bicarbonate transport across the epithelium. The Cl-/HCO3- exchanger SLC26A9 was inhibited by NH4+, which also is produced by H. pylori. The mRNA levels of SLC26A9 were upregulated in infected mice, suggesting a way to overcome the inhibition of the transporter. Furthermore, the hyperemic response to acid pH 2 and 1.5 was abolished in these mice. The mechanisms by which the bacteria could alter the blood flow response might involve inhibition of the epithelial iNOS.Water extracts of H. pylori (HPE) reduces the blood flow acutely through an iNOS and nerve-mediated pathway, possibly through the endogenous iNOS inhibitor ADMA. Furthermore, HPE alters the blood flow response to acid as the hyperemic response to acid pH 0.8 is accentuated in mice treated with HPE.
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| 4. |
- Henriksnäs, Johanna, et al.
(författare)
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Impaired mucus-bicarbonate barrier in Helicobacter pylori-infected mice
- 2006
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Ingår i: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 291:3, s. G396-G403
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Tidskriftsartikel (refereegranskat)abstract
- To resist the harsh intrinsic milieu, several lines of defense exist in the stomach. The aim of this study was to investigate the effect of the gastric pathogen Helicobacter pylori on these mechanisms in vivo. We used FVB/N mice expressing human alpha-1,3/4-fucosyl transferase ( producing Lewis b epitopes) and inoculated with H. pylori 1. Mice were anesthetized with isoflurane or Hypnorm-midazolam, the stomach was exteriorized, and the surface of the corpus mucosa was exposed. Mucus thickness was measured with micropipettes, juxtamucosal pH (pH(jm)) was measured with pH-sensitive microelectrodes, blood flow was measured with laser-Doppler flowmetry, and mRNA levels of the bicarbonate transporter SLC26A9 were quantified with real-time PCR. The increase in mucosal blood flow seen in response to luminal acid (pH 1.5) in control animals (140 +/- 9% of control) was abolished in infected mice. The firmly adherent mucus layer was significantly thinner in infected mice (31 +/- 2 mu m) than in control mice (46 +/- 5 mu m), and no mucus accumulation occurred in infected mice. pHjm decreased significantly more on exposure to luminal acid in infected mice ( luminal pH 1.5, pH(jm) 2.4 +/- 0.7) than in control mice (pH(jm) 6.4 +/- 0.5). Despite reduced pHjm, SLC26A9 mRNA expression was significantly, by increased 1.9-fold, in infected mice. The reduction in pH(jm) by infection with H. pylori might be due to a reduced firmly adherent mucus layer, increased mucus permeability to H+, and/or inhibition of bicarbonate transport. The upregulation of SLC26A9 in H. pylori-infected epithelium might be a result of continuous inhibition of the transporter, e. g., by ammonium, a H. pylori product, which has been previously shown to inhibit SLC26A9.
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| 5. |
- Ljungdahl, Mikael, et al.
(författare)
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Inflammatory response in patients with malignant obstructive jaundice
- 2007
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 42:1, s. 94-102
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Surgery in patients with malignant obstructive jaundice is associated with increased risks for postoperative septic complications. The aim of this study was to investigate the inflammatory and the local cellular immune response in patients accepted for surgery because of tumours in the hepatic-pancreatic-biliary (HPB) tract. Material and methods. Patients with obstructive jaundice (group HPB+) were compared with those without (HPB-). Patients undergoing surgery for benign abdominal disorders served as controls. Obstructive jaundice was present in 18 out of 33 HPB patients. Preoperatively, blood was analysed for bacteria, endotoxins and cytokines (TNF-α, IL-6 and IL-10). At operation, mesenteric lymph nodes (MLNs) were excised for bacterial cultures using standard microbiological techniques, and immunohistochemistry, using antibodies CD4 and CD8 (mainly staining T lymphocytes), CD68 (macrophages), and anti-caspase-3 (to determine the rate of apoptosis). Results. Bacterial translocation was not demonstrated in any of the patients. Increased preoperative concentrations of endotoxins were found in group HPB+. The number of macrophages and the rate of apoptosis in MLNs were increased in jaundiced patients, while the number of T lymphocytes was decreased. Conclusions. Malignant obstructive jaundice causes increased blood concentrations of endotoxins and cytokines, an increased number of macrophages in MLNs, a higher rate of apoptosis in MLNs, but a decreased number of T lymphocytes in MLNs. The lymphocyte depletion is probably due to the increased rate of apoptosis, and might reduce the ability of jaundiced patients to eradicate infection.
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