Sequential therapy is statistically significant compared with standard therapy for eradicating H. pylori infection and is statistically significantly more effective in patients with clarithromycin-resistant strains. Side effects are similar with both treatment regimens and are rarely severe enough to cause discontinuation of therapy. ClinicalTrials.gov registration number: NCT00403364.

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To investigate the potential involvement of the nitric oxide (NO) pathway in colorectal carcinogenesis, we correlated the expression and the activity of inducible nitric oxide synthase (iNOS) with the degree of tumor angiogenesis in human colorectal cancer. Tumor samples and adjacent normal mucosa were obtained from 46 surgical specimens. Immunohistochemical expression of iNOS, vascular endothelial growth factor (VEGF), and CD31 was analyzed on paraffin-embedded tissue sections. iNOS activity and cyclic GMP levels were assessed by specific biochemical assays. iNOS protein expression was determined by Western blot analysis. iNOS and VEGF mRNA levels were evaluated using Northern blot analysis. Both iNOS and VEGF expressions correlated significantly with intratumor microvessel density (r(s) = 0.31, P = 0.02 and r(s) = 0.67, P < 0.0001, respectively). A significant correlation was also found between iNOS and VEGF expression (P = 0.001). iNOS activity and cyclic GMP production were significantly higher in the cancer specimens than in the normal mucosa (P < 0.0001 and P < 0.0001, respectively), as well as in metastatic tumors than in nonmetastatic ones (P = 0.002 and P = 0.04, respectively). Western and Northern blot analyses confirmed the up-regulation of the iNOS protein and gene in the tumor specimens as compared with normal mucosa. NO seems to play a role in colorectal cancer growth by promoting tumor angiogenesis.

Purpose: Activity of histidine decarboxylase, the key enzyme in the synthesis of histamine, has been shown to be increased in several types of human tumors.We attempted to establish whether the possible involvement of histidine decarboxylase and histamine in colorectal carcinogenesis might be mediated by the activation of the cyclooxygenase-2 (COX-2) pathway. Experimental Design: Expression/activity of histidine decarboxylase, histamine content, and prostaglandin E 2 (PGE 2 ) production were analyzed in 33 colorectal cancer samples and in the HT29, Caco-2, and HCT116 colon cancer cell lines. The effects of histamine, celecoxib, and H 1 , H 2 , and H 4 receptor antagonists on COX-2 expression/activity, cell proliferation, and vascular endothelial growth factor (VEGF) production were assessed in the three colon cancer lines that showed different constitutive COX-2 expression. Results: We showed the up-regulation of histidine decarboxylase protein expression and activity in the tumor specimens when compared with normal colonic mucosa. Histidine decarboxylase activity and histamine content were also significantly higher in metastatic tumors than in nonmetastatic ones.These variables significantly correlated with tumor PGE 2 production.The administration of histamine increased COX-2 expression/activity, cell proliferation, and VEGF production in the COX-2-positive HT29 and Caco-2 cells. Treatment with either H 2 /H 4 receptor antagonists or celecoxib prevented these effects. Histamine had no effect on both the COX-2 pathway andVEGF production in the COX-2-negative HCT116 cells. Conclusions: Our data showed that histamine exerts both a proproliferative and a proangiogenic effect via H 2 /H 4 receptor activation. These effects are likely to be mediated by increasing COX-2-related PGE 2 production in COX-2-expressing colon cancer cells.

False negative breath and stool tests are equally common in patients taking proton pump inhibitors. Antacids do not impair the sensitivity of the breath tests or the stool test.

Background: A standard third-line treatment is lacking, and European guidelines recommend performing culture in these patients. However, the use of this procedure as 'routine practice' is definitively not feasible. Aim: To evaluate the eradication rate of a 10-day levofloxacin-based triple therapy in patients who have failed two eradication courses for Helicobacter pylori. Methods: A total of 151 patients with persistent Helicobacter pylori infection after two treatments were studied. Patients were considered positive if two of three endoscopic tests were positive. Susceptibility testing was also performed. Patients received a standard dose of

Purpose: Up-regulation of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) enzymes has been reported in colorectal cancer. We aimed at evaluating the possible interaction between the nitric oxide and COX-2 pathways, and its effect on promoting tumor angiogenesis.Experimental Design: Expression of iNOS, COX-2, vascular endothelial growth factor (VEGF), and CD31 was analyzed in tumor samples and corresponding normal mucosa obtained from 46 surgical specimens. We also evaluated iNOS activity, prostaglandin E 2 (PGE 2 ), cyclic GMP and cyclic AMP production in the same specimens. Nitrite/nitrate levels, and PGE 2 and VEGF production were assessed in HCT116 and HT29 colon cancer cell lines after induction and selective inhibition of the two enzyme pathways.Results: A significant correlation was found between iNOS and COX-2 immunohistochemical expression. PGE 2 production significantly correlated with iNOS activity and cGMP levels. A significant correlation was also found among PGE 2 production, microvessel density, and VEGF expression. Coinduction of both iNOS and COX-2 activities occurred after lipopolysaccharide (LPS) and epidermal growth factor (EGF) treatment in HCT116 and HT29 cells. Inhibition of iNOS by 1400W significantly reduced both LPS-and EGF-induced PGE 2 production. Treatment with LPS, EGF, and arachidonic acid significantly increased VEGF production in the iNOS-negative/COX-2-positive HT29 cells. This effect was completely reversed by treatment with the selective COX-2 inhibitor celecoxib.Conclusions: Our data showed a prominent role of nitric oxide in stimulating COX-2 activity in colorectal cancer. This interaction is likely to produce a cooperative effect in promoting angiogenesis through PGE 2 -mediated increase in VEGF production.

This study showed that: (i) there is a relevant discordance between the two methods; and (ii) phenotypic clarithromycin resistance markedly reduces H. pylori eradication when it is linked to a specific point mutation.