Recent use of proton pump inhibitor-based triple therapies for the eradication of H pylori: a broad data review

Development of Genetically Encoded Biosensors for Reporting the Methyltransferase-Dependent Biosynthesis of Semisynthetic Macrolide Antibiotics

Clarithromycin is an improved semisynthetic analogue of the naturally occurring macrolide, erythromycin. The subtle modification of a methyl group on the C-6 hydroxyl group endows the molecule with improved acid stability and results in a clinically useful antibiotic. Here, we show that the effector specificity of the biosensor protein, MphR, can be evolved to selectively recognize clarithromycin and therefore report on the production of this molecule in vivo. In addition, a crystal structure of the evolved variant reveals the molecular basis for selectivity and provides a guide for the evolution of a new metabolic function using this biosensor.

Standard triple therapy in Helicobacter pylori eradication in Turkey: Systematic evaluation and meta-analysis of 10-year studies

BACKGROUND/AIMS

This study aims at evaluating the mean eradication rate by a systematic compilation of the studies which involved the standard triple therapy (STT) in first-line Helicobacter pylori (Hp) eradication in Turkey over a period of 10 years between 2004 and 2013 using the meta-analysis method.

MATERIALS AND METHODS

The systematic compilation and meta-analysis were carried out according to the PRISMA standards defined in the Cochrane handbook. The results of full-text studies published in national and international journals in English and Turkish languages on Turkish population in a period of 10 years, from 2004 to 2013, are included in this study. The studies include open-label trials, controlled trials, treatment arms, and case series that included a triple therapy regimen consisting of standard doses of a proton pump inhibitor (PPI; omeprazole 20 mg BID, lansoprazole 30 mg BID, pantoprazole 40 mg BID, esomeprazole 40 mg BID, or rabeprazole 20 mg BID) along with clarithromycin 500 mg BID and amoxicillin 1 g BID for 7-14 days. They were scanned electronically via the search engines Google Scholar, PubMed, and the Turkish Medicine Index using specific keywords. The related keywords used were Turkey, Helicobacter pylori, infection, standard triple treatment, first-line therapy, eradication, omeprazole, lansoprazole, pantoprazole, rabeprazole, esomeprazole, clarithromycin, and amoxicillin. Studies carried out with adults were included in the evaluation. The publication year of the studies and the included number of patients, their age, gender, treatment duration (7, 10, and 14 days), and PPIs used were evaluated by two separate gastroenterologists and biostatisticians. Studies that used at least one reliable method (histology, urea breath test (UBT), or Helicobacter pylori stool antigen (HpSA) test) four weeks after completing the treatment for the control of Hp eradication were included. Only naive patients were accepted, and patients who had previously received eradication treatment were excluded. The effectiveness of the Hp eradication was analyzed using an intention-to-treat (ITT) or per-protocol (PP) analysis.

RESULTS

The STT regime of 45 studies complying with the inclusion criteria was evaluated. A total of 3715 patients were included in the study. Of the 3010 patients whose gender information was available, 55% were women and 45% were men; the weighted age average given explicitly in the studies was 42.14±0.67. The treatment lasted for 14 days in 42 studies, for 7 days in six studies, and for 10 days in 1 study. The eradication rates evaluated according to the ITT and PP analyses were 60% (95% CI: 56%-63%) and 57% (95% CI: 51%-62%), respectively. The rates for 7 days of treatment were 57% (95% CI: 46%-68%) and 60% (95% CI: 51%-67%) and for 14 days of treatment were 60% (95% CI: 56%-63%) and 56% (95% CI: 50%-62%), respectively. The ITT eradication rate of the only 10-day study was 78% (95% CI: 66%-86%). In the meta-regression analysis, the treatment duration, PPI, age, and gender ratio (women/men) used for the ITT analysis had no effect. The gender ratio and age were not considered in this analysis because they were not clearly stated in studies using the PP analysis. The duration of treatment and the PPI used had no effect.

CONCLUSION

A systematic meta-analysis of studies conducted during the period 2004-2013 in Turkey revealed that the rate of first-line Hp eradication using STT was unacceptably low, and the duration of treatment and PPI used made no difference.

The inhibitory effect of flavonoids on interleukin-8 release by human gastric adenocarcinoma (AGS) cells infected with cag PAI (+) Helicobacter pylori

Introduction

It is well known that the presence of Helicobacter pylori in the stomach induces gastritis and causes an immune response. Exposure of gastric epithelial cell lines to this germ induces the secretion of interleukin-8 (IL-8), which is a potent PMN-activating chemotactic cytokine. Interleukin-8 is usually elevated in gastric biopsy samples of patients with H. pylori-associated gastritis and significantly increases in the supernatant of in vitro cultivated biopsy samples of gastric mucosa with active H. pylori gastritis. Interleukin-8 is an activating factor for leucocytes and other pro-inflammatory factors, free radicals, and proteolytic enzymes. That is why natural compounds potentially useful in therapy are still investigated – among them flavonoids. They reveal anti-oxidative and anti-inflammatory activities and significantly inhibit the gastric mucosa damage.

The aim of the study

Was the estimation of the anti-inflammatory effects of flavonoids on H. pylori-induced activation of human gastric adenocarcinoma cells (AGS). After infection of AGS cells by cag PAI (+) H. pylori in vitro, secretion of IL-8, effects of flavonoids on viability of AGS cells, and effects of flavonoids on increase of H. pylori were determined. Such flavones as chrysin, quercetin, kaemferide, flavanone, galangin, and kaempferol were examined.

Results

This study has shown an inhibitory effect of flavonoids on the release of IL-8 through infected AGS cells (except chrysin), and no toxic effects to AGS cells were observed. Galangin revealed antibacterial effects against H. pylori. Flavonoids limit the inflammatory process through the inhibition of IL-8 release in infected AGS cells with H. pylori. The strongest inhibitor of IL-8 was galangin.

Comparative study of Nigella Sativa and triple therapy in eradication of Helicobacter Pylori in patients with non-ulcer dyspepsia

BACKGROUND/AIM

A large number of diseases are ascribed to Helicobacter pylori (H. pylori), particularly chronic active gastritis, peptic ulcer disease and gastric cancer. Successful treatment of H. pylori infection with antimicrobial agents can lead to regression of H. pylori-associated disorders. Antibiotic resistance against H. pylori is increasing, and it is necessary to find new effective agents. Nigella sativa seed (NS), a commonly used herb, possesses in vitro anti-helicobacter activity. The present study was undertaken to evaluate the efficacy of NS in eradication of H. pylori infection in non-ulcer dyspeptic patients.

MATERIALS AND METHODS

The study was conducted on 88 adult patients attending King Fahd Hospital of the University, Al-Khobar, Saudi Arabia, from 2007 to 2008, with dyspeptic symptoms and found positive for H. pylori infection by histopathology and urease test. Patients were randomly assigned to four groups, receiving i) triple therapy (TT) comprising of clarithromycin, amoxicillin, omeprazole [n= 23], ii) 1 g NS + 40 mg omeprazole (OM) [n= 21], iii) 2 g NS + OM [n= 21] or iv) 3 g NS + OM [n= 23]. Negative H. pylori stool antigen test four weeks after end of treatment was considered as eradication.

RESULTS

H. pylori eradication was 82.6, 47.6, 66.7 and 47.8% with TT, 1 g NS, 2 g NS and 3 g NS, respectively. Eradication rates with 2 g NS and TT were statistically not different from each other, whereas H. pylori eradication with other doses was significantly less than that with TT (P < 0.05). Dyspepsia symptoms improved in all groups to a similar extent.

CONCLUSIONS

N. sativa seeds possess clinically useful anti-H. pylori activity, comparable to triple therapy. Further clinical studies combining N. sativa with antibiotics are suggested.

Preparation and evaluation of anti-Helicobacter pylori efficacy of chitosan nanoparticles in vitro and in vivo

The aim of this study was to formulate and systematically evaluate in vitro and in vivo Helicobacter pylori (Hp) efficacy of chitosan (CS) nanoparticles (NPs). CS NPs were prepared by the polymerid dispersion method. The in vitro anti-Hp effect of concentration, pH and deacetylation degree of CS NP solutions was detected. Then, 60 BALB/c mice were randomly divided into 3 groups and Hp-infected mice were established by inoculating with Hp strain. Thereafter that, mice in different groups received PBS, CS solution of CS NP solution intragastrically, twice daily for 14 consecutive days. Four weeks after the last administration, the mice were killed and part of the gastric mucosa was embedded in paraffin, cut into sections and assayed with Giemsa staining. Part of the gastric mucosa was used to quantitatively culture Hp. At pH 4-6, the anti-Hp effect of CS NP solution had a negative correlation with pH value (P < 0.01), and the optimal pH value was 4; there was a significant difference in anti-Hp effect between 88.5% deacelytation degree (DD88.5) CS NP and 95% deacelytation degree (DD95) CS NP (P < 0.05-0.01). The anti-Hp effect ranked from high to low, i.e., from DD95 CS NP to DD88.5 CS NP; the anti-Hp effect of DD88.5 CS NP and DD95 CS NP showed no difference within between 5 and 20 g/l (P > 0.05). The Hp eradication rate was 0, 55 and 75%, respectively, among the three groups (P < 0.01) and the Hp colonized density in the control group and CS group was significantly higher than that in the CS NP group (P < 0.01, 0.05). These results suggest that CS NP improves the anti-Hp efficacy of CS in vitro or in vivo and has the potential to kill Hp directly.

Emodin targets the beta-hydroxyacyl-acyl carrier protein dehydratase from Helicobacter pylori: enzymatic inhibition assay with crystal structural and thermodynamic characterization

Background

The natural product Emodin demonstrates a wide range of pharmacological properties including anticancer, anti-inflammatory, antiproliferation, vasorelaxant and anti-H. pylori activities. Although its H. pylori inhibition was discovered, no acting target information against Emodin has been revealed to date.

Results

Here we reported that Emodin functioned as a competitive inhibitor against the recombinant β-hydroxyacyl-ACP dehydratase from Helicobacter pylori (HpFabZ), and strongly inhibited the growth of H. pylori strains SS1 and ATCC 43504. Surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) based assays have suggested the kinetic and thermodynamic features of Emodin/HpFabZ interaction. Additionally, to inspect the binding characters of Emodin against HpFabZ at atomic level, the crystal structure of HpFabZ-Emodin complex was also examined. The results showed that Emodin inhibition against HpFabZ could be implemented either through its occupying the entrance of the tunnel or embedding into the tunnel to prevent the substrate from accessing the active site.

Conclusion

Our work is expected to provide useful information for illumination of Emodin inhibition mechanism against HpFabZ, while Emodin itself could be used as a potential lead compound for further anti-bacterial drug discovery.

Phytoceuticals: mighty but ignored weapons against Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection causes peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphomas and gastric adenocarcinomas, for which the pathogenesis of chronic gastric inflammation prevails and provides the pathogenic basis. Since the role of H. pylori infection is promoting carcinogenesis rather than acting as a direct carcinogen, as several publications show, eradication alone cannot be the right answer for preventing H. pylori-associated gastric cancer. Therefore, a non-antimicrobial approach has been suggested to attain microbe-associated cancer prevention through controlling H. pylori-related chronic inflammatory processes and mediators responsible for carcinogenesis. Phytoceutical is a term for plant products that are active on biological systems. Phytoceuticals such as Korean red ginseng, green tea, red wine, flavonoids, broccoli sprouts, garlic, probiotics and flavonoids are known to inhibit H. pylori colonization, decrease gastric inflammation by inhibiting cytokine and chemokine release, and repress precancerous changes by inhibiting nuclear factor-kappa B DNA binding, inducing profuse levels of apoptosis and inhibiting mutagenesis. Even though further unsolved issues are awaited before phytoceuticals are accepted as a standard treatment for H. pylori infection, phytoceuticals can be a mighty weapon for either suppressing or modulating the disease-associated footprints of H. pylori infection.

Effects of a one-week treatment with acid gastric inhibitors on Helicobacter pylori-infected mice

OBJECTIVE

Antiacid drugs, including omeprazole and ranitidine, were prescribed to Helicobacter pylori-infected subjects in combination with antibiotics during eradication treatment. Several reports suggest that these drugs have additional pharmacological properties, such as antineutrophil, antiapoptotic and antioxidant characteristics. The aim of this work was to study the effects of acid suppressive medication treatment in the H. pylori infection experimental model, focusing on possible additional pharmacological properties.

MATERIAL AND METHODS

The ability of gastric acid suppression was assessed in pylorus-ligated animals. Gastric H. pylori colonization levels, myeloperoxidase (MPO) acitivity, macroscopic damage, Bax and Bcl-2 expression and DNA damage levels were assessed in C57BL/6-infected mice after treatment for one week with omeprazole (100 mg kg(-1)) or ranitidine (100 mg kg(-1)).

RESULTS

Omeprazole treatment increased bacteria colonization and MPO activity in mice stomachs. Both antiacid drugs efficiently improved macroscopic damage, although only omeprazole restored the expression of the antiapoptotic Bcl-2 protein in gastric mucosa of infected animals.

CONCLUSIONS

Some additional omeprazole-related properties, such as antineutrophil properties, were not observed in H. pylori-infected mice after one week of treatment, suggesting that this property is restricted to in vitro approaches. However, the antiapoptotic activity of omeprazole could be attributed to an ability to modify the protein expression of Bcl-2, decreased by H. pylori infection.

The efficacy of bismuth containing quadruple therapy as a first-line treatment option for Helicobacter pylori

BACKGROUND

Helicobacter pylori eradication rates have tended to decrease recently, mostly due to increasing antibiotic-resistance. The present study aimed to compare the efficacy of bismuth-based quadruple regimen with proton pump inhibitor-based triple regimen for eradication of H. pylori.

METHODS

Consecutive H. pylori-positive patients with non-ulcer dyspepsia were randomized into one of two regimens: (i) bismuth subsalicylate 300 mg q.i.d., lansoprazole 30 mg b.i.d., tetracycline 500 mg q.i.d. and metronidazole 500 mg t.i.d. (BLTM group) for 14 days; (ii) lansoprazole 30 mg b.i.d., amoxicillin 1 g b.i.d and clarithromycin 500 mg b.i.d. (LAC) for 14 days. Gastroscopy and (14)C-Urea breath test (UBT) were performed before enrollment, and UBT only was repeated for 6 weeks after treatment.

RESULTS

A total of 240 patients were randomized into groups and 212 of them completed the protocols. The 'intention-to-treat' (ITT) and 'per protocol' (PP) H. pylori eradication rates were 70% (95%CI 61-78) and 82.3% (95%CI 74-89) in the BLTM group, and 57.5% (95%CI 48-66) and 62.7% (95%CI 53-71) in the LAC group. The BLTM treatment achieved a significantly better eradication rate compared with LAC treatment in PP analysis (82.3% vs. 62.7%, P = 0.002). Mild to severe side-effects, which were more frequent in the BLTM group, were reported in 18.2% of the patients.

CONCLUSION

The bismuth-based quadruple regimen achieved a better eradication rate compared with proton pump inhibitor-based triple regimens as a first-line eradication option for H. pylori in our population.

One-week versus two-week furazolidone-based quadruple therapy as the first-line treatment for Helicobacter pylori infection in Iran

BACKGROUND AND AIM

Furazolidone-based regimens for the eradication of Helicobacter pylori are low cost and effective although less tolerable. Our aim was to compare the efficacy and compliance of 1-week furazolidone-based quadruple therapy (furazolidone, amoxicillin, bismuth subcitrate, omeprazole; FABO) with 2-week quadruple therapy using the same drugs.

METHODS

One hundred and fifty-six consecutive patients with H. pylori related diseases were enrolled in our study. The patients were randomized into two groups of FABO1 and FABO2 groups receiving, 1 or 2 weeks' quadruple H. pylori eradication therapies, respectively, as follows: furazolidone (200 mg twice daily), amoxicillin (1 g twice daily), bismuth (240 mg twice daily) and omeprazole (20 mg twice daily). The chi(2) test was used to compare the efficacy of the therapies.

RESULTS

The per-protocol eradication rate in FABO1 and FABO2 groups were 56/66 (84.8%) and 57/69 (82.6%), respectively. The intention-to-treat eradication rate was 56/78 (71.8%) in FABO1 group and 57/78 (73.1%) in FABO2 group. There was not any significant statistical difference between two groups. A significant decrease in compliance in FABO2 group was seen.

CONCLUSION

This is an encouraging report showing a therapy with possible success in decreasing the duration of H. pylori infection as well as reaching the eradication rate of 80%.

American College of Gastroenterology guideline on the management of Helicobacter pylori infection

Helicobacter pylori (H. pylori) remains a prevalent, worldwide, chronic infection. Though the prevalence of this infection appears to be decreasing in many parts of the world, H. pylori remains an important factor linked to the development of peptic ulcer disease, gastric malignanc and dyspeptic symptoms. Whether to test for H. pylori in patients with functional dyspepsia, gastroesophageal reflux disease (GERD), patients taking nonsteroidal antiinflammatory drugs, with iron deficiency anemia, or who are at greater risk of developing gastric cancer remains controversial. H. pylori can be diagnosed by endoscopic or nonendoscopic methods. A variety of factors including the need for endoscopy, pretest probability of infection, local availability, and an understanding of the performance characteristics and cost of the individual tests influences choice of evaluation in a given patient. Testing to prove eradication should be performed in patients who receive treatment of H. pylori for peptic ulcer disease, individuals with persistent dyspeptic symptoms despite the test-and-treat strategy, those with H. pylori-associated MALT lymphoma, and individuals who have undergone resection of early gastric cancer. Recent studies suggest that eradication rates achieved by first-line treatment with a proton pump inhibitor (PPI), clarithromycin, and amoxicillin have decreased to 70-85%, in part due to increasing clarithromycin resistance. Eradication rates may also be lower with 7 versus 14-day regimens. Bismuth-containing quadruple regimens for 7-14 days are another first-line treatment option. Sequential therapy for 10 days has shown promise in Europe but requires validation in North America. The most commonly used salvage regimen in patients with persistent H. pylori is bismuth quadruple therapy. Recent data suggest that a PPI, levofloxacin, and amoxicillin for 10 days is more effective and better tolerated than bismuth quadruple therapy for persistent H. pylori infection, though this needs to be validated in the United States.

Eradication of Helicobacter pylori with triple therapy: an epidemiologic analysis of trends in Turkey over 10 years

BACKGROUND

There is increasing concern about the efficacy of current regimens for the eradication of Helicobacter pylori.

OBJECTIVES

This study examined rates of H. pylori eradication with a commonly used triple-therapy regimen consisting of a proton pump inhibitor (PPI), clarithromycin, and amoxicillin in trials performed in Turkey from 1996 to 2005. It also investigated the relationship between eradication rates and the duration of treatment (7, 10, or 14 days), choice of PPI, and indication for treatment (dyspepsia or peptic ulcer).

METHODS

This was a retrospective epidemiologic analysis. Articles concerning H. pylori eradication in Turkey that were published in peer-reviewed national and international journals were identified through searches of MEDLINE using the terms Helicobacter, eradication, and Turkey, and of the Turkish Medical Index using the terms Helicobacter and eradication. Abstracts from the Turkish Gastroenterology Congress from 1996 through 2005 were searched manually. Open-label trials, controlled trials, treatment arms, and case series that included a triple-therapy regimen consisting of standard doses of any PPI (omeprazole 20 mg BID, lansoprazole 30 mg BID, pantoprazole 40 mg BID, or esomeprazole 40 mg BID) with clarithromycin 500 mg BID and amoxicillin 1 g BID for 7 to 14 days were selected for analysis. Trials including patients who had undergone a previous attempt at eradication of H. pylori were excluded.

RESULTS

Of 138 trials or treatment arms identified, 94 met the criteria for inclusion (3637 subjects). The pooled eradication rate was 68.8% (95% CI, 67.3-70.3). A marked decrease in eradication was noted after 2000. Pooled eradication rates each year from 1996 through 2005 were 79.4%, 83.7%, 81.8%, 81.8%, 75.1%, 61.3%, 65.6%, 65.1%, 55.3%, and 61.1%, respectively. Eradication rates were not affected by the duration of treatment, choice of PPI, or indication for treatment.

CONCLUSIONS

Rates of H. pylori eradication with the triple-therapy regimen decreased in Turkey over the 10-year period studied. In an era of increasing clarithromycin use, the effectiveness of this regimen for H. pylori eradication appears to require reassessment.

5-LOX inhibitor modulates the inflammatory responses provoked by Helicobacter pylori infection

BACKGROUND

Arachidonic acid metabolites have been considered as pivotal mediators in Helicobacter pylori-induced inflammatory response, which are mainly metabolized by two distinct enzymes: cyclooxygenase (COX) and lipoxygenase (LOX). While COX has become well known to play a key role in either carcinogenesis or inflammation related to H. pylori infection, little is known regarding the implication of LOX in H. pylori infection. In this study, we evaluated the roles of 5-LOX and its metabolites in H. pylori-induced host responses and further a potential beneficial action of specific LOX inhibitors against H. pylori infection.

MATERIALS AND METHODS

Expressions of cytosolic phospholipase A(2) (cPLA(2)), COX-2, and 5-LOX after H. pylori infection were evaluated by immunofluorescence staining and Western blotting. Synthesis of LOX metabolites was measured with reversed-phase high-performance liquid chromatography. For analyzing the influence of 5-LOX inhibitors, nordihydroguaiaretic acid (NDGA) and geraniin, on H. pylori-induced inflammatory responses, RNase protection assay and RT-PCR were performed.

RESULTS

H. pylori stimulated the translocation of cPLA(2) from cytoplasm to nucleus and increased the biosynthesis of hydroxyeicosatetraenoic acids (HETEs) as a predominant form of 5S-HETE in gastric epithelium. NDGA exerted a strong suppression activity of H. pylori-induced 5-LOX signaling. The administration of LOX inhibitors was related with down-expression of proinflammatory mediators such as interleukin-8 and tumor necrosis factor-alpha in both H. pylori-infected gastric epithelial cells and macrophage cells.

CONCLUSION

LOX modulation with its specific inhibitors could impose significant anti-inflammatory responses after H. pylori infection, based on the fact that H. pylori infection provoked gastric inflammation through metabolizing arachidonic acid by the 5-LOX pathway.

Discovery of Helicobacter pylori shikimate kinase inhibitors: Bioassay and molecular modeling

Shikimate kinase (SK) is the fifth enzyme in the shikimate pathway and catalyzes the phosphate transfer from ATP to shikimate in generating shikimate 3-phosphate and ADP. SK has been developed as a promising target for the discovery of antibacterial agents. In this report, two small molecular inhibitors (compound 1, 3-methoxy-4-{[2-({2-methoxy-4-[(4-oxo-2-thioxo-1,3-thiazolidin-5-ylidene)methyl]phenoxy}methyl)benzyl]oxy}benzaldehyde; compound 2, 5-bromo-2-(5-{[1-(3,4-dichlorophenyl)-3,5-dioxo-4-pyrazolidinylidene]methyl}-2-furyl)benzoic acid) against Helicobacter pylori SK (HpSK) were successfully identified with IC(50) values of 5.5+/-1.2 and 6.4+/-0.4 microM, respectively. The inhibition kinetics shows that compound 1 is a noncompetitive inhibitor with respect to both shikimate and MgATP, and compound 2 is a competitive inhibitor toward shikimate and noncompetitive inhibitor with respect to MgATP. The surface plasmon resonance (SPR) technology based analysis reveals that the equilibrium dissociation constants (K(D)s) of compounds 1 and 2 with HpSK enzyme are 4.39 and 3.74 microM, respectively. The molecular modeling and docking of two inhibitors with HpSK reveals that the active site of HpSK is rather roomy and deep, forming an L-shape channel on the surface of the protein, and compound 1 prefers the corner area of L-shape channel, while compound 2 binds the short arm of the channel of SK in the binding interactions. It is expected that our current work might supply useful information for the development of novel SK inhibitors.

Biochemical characterization and inhibitor discovery of shikimate dehydrogenase from Helicobacter pylori

Shikimate dehydrogenase (SDH) is the fourth enzyme involved in the shikimate pathway. It catalyzes the NADPH-dependent reduction of 3-dehydroshikimate to shikimate, and has been developed as a promising target for the discovery of antimicrobial agent. In this report, we identified a new aroE gene encoding SDH from Helicobacter pylori strain SS1. The recombinant H. pylori shikimate dehydrogenase (HpSDH) was cloned, expressed, and purified in Escherichia coli system. The enzymatic characterization of HpSDH demonstrates its activity with k(cat) of 7.7 s(-1) and K(m) of 0.148 mm toward shikimate, k(cat) of 7.1 s(-1) and K(m) of 0.182 mm toward NADP, k(cat) of 5.2 s(-1) and K(m) of 2.9 mm toward NAD. The optimum pH of the enzyme activity is between 8.0 and 9.0, and the optimum temperature is around 60 degrees C. Using high throughput screening against our laboratory chemical library, five compounds, curcumin (1), 3-(2-naphthyloxy)-4-oxo-2-(trifluoromethyl)-4H-chromen-7-yl 3-chlorobenzoate (2), butyl 2-{[3-(2-naphthyloxy)-4-oxo-2-(trifluoromethyl)-4H-chromen-7-yl]oxy}propanoate (3), 2-({2-[(2-{[2-(2,3-dimethylanilino)-2-oxoethyl]sulfanyl}-1,3-benzothiazol-6-yl)amino]-2-oxoethyl}sulfanyl)-N-(2-naphthyl)acetamide (4), and maesaquinone diacetate (5) were discovered as HpSDH inhibitors with IC(50) values of 15.4, 3.9, 13.4, 2.9, and 3.5 microm, respectively. Further investigation indicates that compounds 1, 2, 3, and 5 demonstrate noncompetitive inhibition pattern, and compound 4 displays competitive inhibition pattern with respect to shikimate. Compounds 1, 4, and 5 display noncompetitive inhibition mode, and compounds 2 and 3 show competitive inhibition mode with respect to NADP. Antibacterial assays demonstrate that compounds 1, 2, and 5 can inhibit the growth of H. pylori with MIC of 16, 16, and 32 microg.mL(-1), respectively. This current work is expected to favor better understanding the features of SDH and provide useful information for the development of novel antibiotics to treat H. pylori-associated infection.

Peptide deformylase is a potential target for anti-Helicobacter pylori drugs: reverse docking, enzymatic assay, and X-ray crystallography validation

Colonization of human stomach by the bacterium Helicobacter pylori is a major causative factor for gastrointestinal illnesses and gastric cancer. However, the discovery of anti-H. pylori agents is a difficult task due to lack of mature protein targets. Therefore, identifying new molecular targets for developing new drugs against H. pylori is obviously necessary. In this study, the in-house potential drug target database (PDTD, http://www.dddc.ac.cn/tarfisdock/) was searched by the reverse docking approach using an active natural product (compound 1) discovered by anti-H. pylori screening as a probe. Homology search revealed that, among the 15 candidates discovered by reverse docking, only diaminopimelate decarboxylase (DC) and peptide deformylase (PDF) have homologous proteins in the genome of H. pylori. Enzymatic assay demonstrated compound 1 and its derivative compound 2 are the potent inhibitors against H. pylori PDF (HpPDF) with IC50 values of 10.8 and 1.25 microM, respectively. X-ray crystal structures of HpPDF and the complexes of HpPDF with 1 and 2 were determined for the first time, indicating that these two inhibitors bind well with HpPDF binding pocket. All these results indicate that HpPDF is a potential target for screening new anti-H. pylori agents. In addition, compounds 1 and 2 were predicted to bind to HpPDF with relatively high selectivity, suggesting they can be used as leads for developing new anti-H. pylori agents. The results demonstrated that our strategy, reverse docking in conjunction with bioassay and structural biology, is effective and can be used as a complementary approach of functional genomics and chemical biology in target identification.

Evaluation of triple and quadruple Helicobacter pylori eradication therapies in Iranian children: a randomized clinical trial

BACKGROUND

Clinical trials in children concerning Helicobacter pylori eradication treatments are scarce. The purpose of this study was to assess the efficacy of proton pump inhibitor (PPI)-based triple therapy using PPI, amoxicillin and clarithromycin in Iranian children. We also evaluated the efficacy of quadruple therapy with PPI, metronidazole, amoxicilin and bismuth citrate in Iranian children.

METHODS

This was a randomized clinical trial performed in Emam Khomeini Hospital between 2003 and 2004. Patients with confirmed H. pylori infection by histology were divided into two groups in a randomized 1:1 scheme: the triple regimen group (omeprazole, clarithromycin and amoxicillin for 10 days) and the quadruple regimen group (omeprazole, amoxicillin, metronidazole and bismuth citrate for 10 days). The eradication was assessed by the C-urea breath test 4 weeks after the end of treatment and analyzed by per-protocol and intention-to-treat approaches.

RESULTS

One hundred and twenty-two patients (mean age 12.36+/-3.06 years) were entered into the study. Only 100 patients completed the study (50 patients in each regimen group). The eradication rates by triple therapy were 92% and 75.5% for the "per-protocol" and "intention-to-treat" approaches, respectively. In the quadruple regimen group, the eradication rates were 84% by the per-protocol approach and 68.8% in the intention-to-treat approach. Symptom responses to therapy were reported in all patients with successful eradication (88% of all patients).

CONCLUSION

With regard to recent recommendations, we also suggest PPI, amoxicillin and clarithromycin triple therapy as a first-line eradication treatment, and quadruple therapies as a second-line option, in Iranian children.

Laparoscopic treatment of gastroduodenal perforations: comparison with conventional surgery

BACKGROUND

Laparoscopic techniques have been proposed as an alternative to open surgery for the treatment of peptic ulcer perforation. This study compared the outcome of laparoscopic and open approaches for the repair of gastroduodenal perforations.

METHODS

A retrospective review was conducted with 134 consecutive patients treated for gastroduodenal perforations. These patients included 122 with perforated duodenal ulcers, 10 with perforated gastric ulcers, and 2 with iatrogenic duodenal perforations. Whereas 68 patients were treated laparoscopically, 66 patients underwent conventional (open) surgery.

RESULTS

Laparoscopic repair was successful in 65 cases (96 %). The mean operating time was shorter with the laparoscopic technique (68 vs 59 min), but the difference was not significant. The duration of postoperative nasogastric aspiration and time to resumed oral intake were shorter in the laparoscopic group (2.6 vs 4.1 days and 4.4 vs. 5.2 days, respectively; p = 0.043). The postoperative analgetic requirements, and overall complications rate were significantly lower after laparoscopic surgery (p = 0.03 and p = 0.004, respectively). There was no statistically significant difference in hospital stay (5.1 vs 6.1 days) or mortality rate between the two procedures.

CONCLUSION

Laparoscopic repair of gastroduodenal perforations is a safe alternative treatment offering certain significant short-term advantages.

Antibacterial effect of plant extracts against Helicobacter pylori

The aim of this work was to evaluate the antibacterial effect of plant extracts as alternative and[sol ]or as active agents supporting antibiotics for treating Helicobacter pylori infection. The effect of either, ethanolic or aqueous extracts from 17 plant materials were studied against one H. pylori standard strain and 11 clinical isolates using a disc diffusion test and by evaluating the minimum inhibitory concentration (MIC) on solid media. An inhibitory activity against H. pylori strains was recorded in a large percentage of tested plants. MIC values of ethanolic extracts were from two to four concentration steps lower than the aqueous ones. In particular, ethanolic extracts of Cuminum cyminum L. and Propolis expressed MIC90 values of 0.075 mg/mL. The results show a significant in vitro effect of plant extracts against H. pylori that could be considered a valuable support in the treatment of the infection and may contribute to the development of new and safe agents for inclusion in anti-H. pylori regimens.

Effect of high-dose aspirin on Helicobacter pylori eradication

We conducted a pilot study aimed at comparing the efficacy of the standard OAC (omeprazole-amoxicillin-clarithromycin) regimen with a combination of the OAC regimen and aspirin (OACA). Follow-up endoscopic findings showed that the previous ulcers were completely healed in all subjects. The eradication rates (per protocol) were 80.3% (49/61) in the OAC group and 86.7% (52/60) in the OACA group. The eradication rate was not significantly different between the two groups. The most common adverse event was a bad taste, and the overall adverse events were similar in the two groups. The combination of the OAC regimen and aspirin was not significantly superior to the standard OAC regimen, but it was well tolerated in a group of patients with peptic ulcer disease. Its potential for clinical use to augment the efficacy of H. pylori eradication may warrant further investigation.

Response of blood endothelin-1 and nitric oxide activity in duodenal ulcer patients undergoing Helicobacter pylori eradication

AIM: To investigate the effect of Helicobacter pylori eradication on endothelin-1 (ET-1) and nitric oxide (NO) in duodenal ulcer (DU) patients.

METHODS: Sixty-six H pylori-infected active DU patients were consecutively enrolled to receive one-week triple therapy (rabeprazole, amoxicillin and metronidazole) and then one-month rabeprazole therapy. They were asked back to determine ulcer and H pylori status using endoscopy one month later. Thirty-seven healthy controls (H pylori +/-: 17/20) were enrolled for comparison. Blood samples were collected in each visit to measure plasma ET-1 and nitrate/nitrite levels using an enzyme immunoassay kit.

RESULTS: Sixty DU patients finished trial per protocol. The ulcer healing and H pylori-eradication rates were 86.7% and 83.3%, respectively. Plasma ET-1 level in DU patients was higher than that of H pylori-negative and positive controls (3.59±0.96 vs 0.89±0.54 vs 0.3±0.2 pg/mL, P<0.01), while nitrate/nitrite levels among them were also significantly different (8.55±0.71 vs 5.27±0.68 vs 6.39±0.92 µmol/L, P<0.05). H pylori eradication diminished ET-1 levels (3.64±0.55 vs 2.64±0.55 pg/mL, P<0.01) but elevated nitrate/nitrite level (8.16±0.84 vs 11.41±1.42 µmol/L, P<0.05).

CONCLUSION: Both plasma ET-1 and nitrate/nitrite levels increase in active DU patients. After an effective H pylori eradication, DU healing is associated with diminished blood ET-1 level and elevated nitrate/nitrite level.

Antibacterial activity of hydrolyzable tannins derived from medicinal plants against Helicobacter pylori

Helicobacter pylori is a major etiological agent in gastroduodenal disorders. In this study, we isolated 36 polyphenols and 4 terpenoids from medicinal plants, and investigated their antibacterial activity against H. pylori in vitro. All hydrolyzable tannins tested demonstrated promising antibacterial activity against H. pylori. Monomeric hydrolyzable tannins revealed especially strong activity. Other compounds demonstrated minimal antibacterial activity with a few exceptions. A monomeric hydrolyzable tannin, Tellimagrandin I demonstrated time- and dose-dependent bactericidal activity against H. pylori in vitro. On the other hand, hydrolyzable tannins did not affect the viability of MKN-28 cells derived from human gastric epithelium. Hydrolyzable tannins, therefore, have potential as new and safe therapeutic regimens against H. pylori infection. Furthermore, we investigated effects of hydrolyzable tannins on lipid bilayer membranes. All the hydrolyzable tannins tested demonstrated dose-dependent membrane-damaging activity. However, it remains to be elucidated whether their membrane-damaging activity directly contributes to their antibacterial action.

A model for the study of Helicobacter pylori interaction with human gastric acid secretion

We present a comprehensive mathematical model describing Helicobacter pylori interaction with the human gastric acid secretion system. We use the model to explore host and bacterial conditions that allow persistent infection to develop and be maintained. Our results show that upon colonization, there is a transient period (day 1-20 post-infection) prior to the establishment of persistence. During this period, changes to host gastric physiology occur including elevations in positive effectors of acid secretion (such as gastrin and histamine). This is promoted by reduced somatostatin levels, an inhibitor of acid release. We suggest that these changes comprise compensatory mechanisms aimed at restoring acid to pre-infection levels. We also show that ammonia produced by bacteria sufficiently buffers acid promoting bacteria survival and growth.

Dual vs. triple therapy for childhood Helicobacter pylori gastritis: a double-blind randomized multicentre trial

BACKGROUND

Data on the efficacy of eradication treatment for Helicobacter pylori gastritis in children are scarce.

AIM

To evaluate the efficacy of triple therapy with lansoprazole plus amoxicillin and tinidazole vs. dual therapy with amoxicillin and tinidazole in a double-blind randomized multicentre trial, and the usefulness of eradication in terms of long-term symptom resolution.

SUBJECTS

We enrolled 43 consecutive children undergoing endoscopy for upper gastrointestinal dyspepsia with H. pylori gastritis. They underwent a 13C-urea breath test, completed a 2-week symptom diary card, and were randomized. Treatment was given in a Redidose box (Redidose Company Ltd., Brighton, UK) containing either lansoprazole-amoxicillin-tinidazole (triple therapy) or placebo plus amoxicillin-tinidazole (dual therapy) for 1 week. The completion of a 2-week symptom diary card and the performance of a breath test were repeated 6 weeks and 6 months after the end of therapy. One to two years later, a structured telephone interview was conducted with 36 of the children.

RESULTS

According to the breath test, 6 weeks after the end of therapy H. pylori was eradicated in 15 of 22 children on triple therapy [68.2%; 95% confidence interval (CI) = 45-88] and in 15 of 21 children on dual therapy (71%; 95% CI = 48-89; not significant), and 6 months after the end of therapy it was eradicated in 16 of 22 children on triple therapy (72.7%) and in 15 of 21 children on dual therapy. Six months after therapy, symptoms were analysed in 11 H. pylori-positive and 31 H. pylori-negative children, and it was found that dyspeptic symptoms had disappeared or improved in both groups, with no difference between them. One to two years later, 36 children were interviewed. Epigastric pain had recurred in three of 26 H. pylori-negative and in seven of 10 H. pylori-positive children (p = .001); in three of the latter, pain was severe and required additional treatment.

CONCLUSION

One-week triple or dual therapy with two antibiotics achieved similar eradication rates. Soon after treatment, symptoms disappeared or improved in most children irrespective of eradication, but epigastric pain recurred in the majority of the still-infected children within 2 years.

Helicobacter pylori and Gastroesophageal Reflux Disease

Since the rediscovery of Helicobacter pylori two decades ago, it has become increasingly clear that the true relationships between this organism and diseases of the upper gastrointestinal tract are highly complex. H. pylori colonization is a strong risk factor for peptic ulceration and distal gastric cancer; however, gastritis has no adverse consequences for most hosts, and the prevalence of H. pylori is inversely related to gastroesophageal reflux disease (GERD) and its sequelae, which include Barrett's esophagus and esophageal adenocarcinoma. One clinical implication stemming from these data is that H. pylori eradication may not be appropriate in certain human populations due to potential beneficial effects conferred by persistent gastric inflammation. However, the majority of published intervention trials indicate that H. pylori treatment neither leads to the development of clinically significant de novo esophagitis nor exacerbates existing reflux disease. Superimposed upon these observations are reports that long-term acid suppression induced by proton-pump inhibitors (PPIs) in conjunction with H. pylori colonization may enhance the development of atrophic gastritis, a well-recognized histologic step in the progression to intestinal-type gastric cancer. Therefore, current evidence-based recommendations regarding management of H. pylori-positive individuals with GERD include the following. H. pylori should not be treated with the intent to either improve reflux symptoms or prevent the development of reflux complications. However, if patients are to receive long-term acid suppressive therapy, they should be tested for H. pylori and treated if positive, due to the potential for PPIs to accelerate atrophy within H. pylori-infected mucosa. Optimal first-line regimens in this country consist of a PPI in combination with clarithromycin and either amoxicillin or metronidazole (triple therapy) for at least 7, but preferably 10, days. Because the most effective second-line regimens contain metronidazole, it is advisable to use amoxicillin instead of metronidazole as first-line therapy in order to optimize results should subsequent therapy be required. If first-line regimens fail to eliminate H. pylori, patients should receive quadruple therapy consisting of a PPI, bismuth subsalicylate, metronidazole, and tetracycline for 14 days. Due to the availability and accuracy of noninvasive diagnostic tests for H. pylori, it is recommended that successful cure be confirmed after intervention.

Treatment of Helicobacter pylori infection

Review of the recently published data on Helicobacter pylori management highlights various interesting aspects. Current H. pylori eradication guidelines generally suggest a noninvasive 'test and treat' strategy for all dyspeptic patients with certain age limits depending on the local gastric neoplasia risk. According to the 'Maastricht 2-2000 Consensus Report' treatment should be thought of as a 'package' considering first- and second-line eradication therapies together. Various centres have published their results using novel antimicrobial formulations and 'rescue' and 'sequential' therapies. Review suggests that care at the specialist level remains a challenge and guidelines are deficient particularly as regards the selection and duration of eradication therapies. Results indicate that differences for CYP2C19 genotype and the selection of proton pump inhibitors have no significant role in determining eradication rates whereas antibiotic resistance and socio-economic factors play a variable role according to different geographical areas. Compliance remains an important factor in determining clinical outcome at the primary and secondary levels worldwide.