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Dive into the research topics where Andreas Mentis is active.

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Featured researches published by Andreas Mentis.


Helicobacter | 2002

Epidemiology and Diagnosis of Helicobacter pylori Infection

Andreas Mentis; Philippe Lehours; Francis Mégraud

Medline, PubMed and the Cochrane databases were searched on epidemiology and diagnosis of Helicobacter pylori for the period of April 2011–March 2012. Several studies have shown that the prevalence of H. pylori infection is decreasing in adults and children in many countries. Various diagnostic tests are available, and most of them have high sensitivity and specificity. The Maastricht IV/Florence consensus report states that the urea breath test using 13C urea remains the best test to diagnose H. pylori infection. Among the stool antigen tests, the ELISA monoclonal antibody test is recommended. All these tests were used, either as a single diagnostic test or in combination, to investigate H. pylori infection among different populations throughout the world. Of particular interest, current improvements in high‐resolution endoscopic technologies enable increased diagnostic accuracy for the detection of H. pylori infection, but none of these techniques, at present, are specific enough for obtaining a real‐time diagnosis of H. pylori infection.


Applied and Environmental Microbiology | 2004

In Vitro and In Vivo Inhibition of Helicobacter pylori by Lactobacillus casei Strain Shirota

Sgouras D; Maragkoudakis P; Petraki K; Martinez-Gonzalez B; Eriotou E; Michopoulos S; Kalantzopoulos G; Effie Tsakalidou; Andreas Mentis

ABSTRACT We studied the potential inhibitory effect of Lactobacillus casei strain Shirota (from the fermented milk product Yakult [Yakult Ltd., Tokyo, Japan]) on Helicobacter pylori by using (i) in vitro inhibition assays with H. pylori SS1 (Sydney strain 1) and nine H. pylori clinical isolates and (ii) the in vivo H. pylori SS1 mouse model of infection over a period of 9 months. In vitro activity against H. pylori SS1 and all of the clinical isolates was observed in the presence of viable L. casei strain Shirota cells but not in the cell-free culture supernatant, although there was profound inhibition of urease activity. In vivo experiments were performed by oral administration of L. casei strain Shirota in the water supply over a period of 9 months to 6-week-old C57BL/6 mice previously infected with H. pylori SS1 (study group; n = 25). Appropriate control groups of H. pylori-infected but untreated animals (n = 25) and uninfected animals given L. casei strain Shirota (n = 25) also were included in the study. H. pylori colonization and development of gastritis were assessed at 1, 2, 3, 6, and 9 months postinfection. A significant reduction in the levels of H. pylori colonization was observed in the antrum and body mucosa in vivo in the lactobacillus-treated study group, as assessed by viable cultures, compared to the levels in the H. pylori-infected control group. This reduction was accompanied by a significant decline in the associated chronic and active gastric mucosal inflammation observed at each time point throughout the observation period. A trend toward a decrease in the anti-H. pylori immunoglobulin G response was measured in the serum of the animals treated with lactobacillus, although this decrease was not significant.


Antimicrobial Agents and Chemotherapy | 2007

In Vitro and In Vivo Activities of Chios Mastic Gum Extracts and Constituents against Helicobacter pylori

Sotirios Paraschos; Prokopios Magiatis; Sofia Mitakou; Kalliopi Petraki; Petros A. Maragkoudakis; Andreas Mentis; Dionyssios N. Sgouras; Alexios-Leandros Skaltsounis

ABSTRACT The extracts and pure major constituents of Chios mastic gum (resin of Pistacia lentiscus var. chia) were tested for their activities against Helicobacter pylori. A total mastic extract without polymer (TMEWP) was prepared after removal of the contained insoluble polymer in order to ameliorate solubility and enhance in vivo activity. Administration of TMEWP to H. pylori SS1-infected mice over the period of 3 months with an average dose of 0.75 mg/day led to an approximately 30-fold reduction in the H. pylori colonization (1.5 log CFU/g of tissue). However, no attenuation in the H. pylori-associated chronic inflammatory infiltration and the activity of chronic gastritis was observed. To further characterize potential active mastic constituents, the TMEWP was separated into an acidic and a neutral fraction. Both were extensively characterized by nuclear magnetic resonance and mass spectroscopy to elucidate the structure of the components contained within each fraction. After chromatographic separation, the acid fraction gave the major triterpenic acids, while the neutral fraction gave several triterpenic alcohols and aldehydes. Mastic extracts and isolated pure triterpenic acids were tested for in vitro activity against a panel of 11 H. pylori clinical strains. The acid fraction was found to be the most active extract (minimum bactericidal concentration [MBC], 0.139 mg/ml), and the most active pure compound was isomasticadienolic acid (MBC, 0.202 mg/ml [0.443 mM]). Our results show that administration of TMEWP may be effective in reducing H. pylori colonization and that the major triterpenic acids in the acid extract may be responsible for such an activity.


Epidemiology and Infection | 1991

ABO blood group, secretor status and detection of Helicobacter pylori among patients with gastric or duodenal ulcers.

Andreas Mentis; C. Caroline Blackwell; Donald M. Weir; C. Spiliadis; A. Dailianas; N. Skandalis

Patients (454) referred for gastroscopy to the General Hospital of Athens were examined to determine (1) if non-secretors were over-represented among patients with ulcers and (2) if there was an association with ABO blood group or secretor status and carriage of Helicobacter pylori. Compared with the local population, among patients with either gastric ulcer (51) or duodenal ulcer (96) there was a significant increase in the proportion of those who were blood group O (P less than 0.025); however, there were no significant differences in the proportions of non-secretors. H. pylori was identified in 62% of the 454 patients: 59.5% of those without evidence of ulcers; 62.5% of those with gastric ulcer; 88% of those with duodenal ulcer (P less than 0.0005). These bacteria were cultured more often and in higher numbers from patients with duodenal ulcer (P less than 0.025). There was no association between ABO blood group and prevalence of H. pylori. The prevalence of H. pylori among non-secretors with gastric ulcer (12.5%) was significantly lower than that for non-secretors with duodenal ulcer (100%) (P less than 0.0005). This was not observed for secretors.


Clinical and Vaccine Immunology | 2005

Lactobacillus johnsonii La1 Attenuates Helicobacter pylori-Associated Gastritis and Reduces Levels of Proinflammatory Chemokines in C57BL/6 Mice

Dionyssios N. Sgouras; Effrosini G. Panayotopoulou; Beatriz Martinez-Gonzalez; Kalliopi Petraki; Spyros Michopoulos; Andreas Mentis

ABSTRACT In clinical settings, Lactobacillus johnsonii La1 administration has been reported to have a favorable effect on Helicobacter pylori-associated gastritis, although the mechanism remains unclear. We administered, continuously through the water supply, live La1 to H. pylori-infected C57BL/6 mice and followed colonization, the development of H. pylori-associated gastritis in the lamina propria, and the levels of proinflammatory chemokines macrophage inflammatory protein 2 (MIP-2) and keratinocyte-derived cytokine (KC) in the serum and gastric tissue over a period of 3 months. We documented a significant attenuation in both lymphocytic (P = 0.038) and neutrophilic (P = 0.003) inflammatory infiltration in the lamina propria as well as in the circulating levels of anti-H. pylori immunoglobulin G antibodies (P = 0.003), although we did not observe a suppressive effect of La1 on H. pylori colonizing numbers. Other lactobacilli, such as L. amylovorus DCE 471 and L. acidophilus IBB 801, did not attenuate H. pylori-associated gastritis to the same extent. MIP-2 serum levels were distinctly reduced during the early stages of H. pylori infection in the La1-treated animals, as were gastric mucosal levels of MIP-2 and KC. Finally, we also observed a significant reduction (P = 0.046) in H. pylori-induced interleukin-8 secretion by human adenocarcinoma AGS cells in vitro in the presence of neutralized (pH 6.8) La1 spent culture supernatants, without concomitant loss of H. pylori viability. These observations suggest that during the early infection stages, administration of La1 can attenuate H. pylori-induced gastritis in vivo, possibly by reducing proinflammatory chemotactic signals responsible for the recruitment of lymphocytes and neutrophils in the lamina propria.


Alimentary Pharmacology & Therapeutics | 2002

Effectiveness of two quadruple, tetracycline‐ or clarithromycin‐containing, second‐line, Helicobacter pylori eradication therapies

Sotirios Georgopoulos; Spiros D. Ladas; S. Karatapanis; Konstantinos Triantafyllou; Charis Spiliadi; Andreas Mentis; V. Artikis; Sotirios A. Raptis

There are no guidelines on second‐line therapies for Helicobacter pylori eradication failures of omeprazole–clarithromycin–amoxicillin triple therapy.


Digestion | 2006

Hypergastrinemia Is Associated with Increased Risk of Distal Colon Adenomas

Sotirios Georgopoulos; Dimitrios Polymeros; Konstantinos Triantafyllou; Charis Spiliadi; Andreas Mentis; Dimitrios G. Karamanolis; Spiros D. Ladas

Background/Aims:Helicobacter pylori infection is a recognized cause of hypergastrinemia, but the association of blood gastrin levels with colonic adenomas (CAs) is controversial. The aim of this study is to investigate if hypergastrinemia, H. pylori infection and/or cagA protein are risk factors for CAs. Methods: In this prospective case-control study, fasting serum samples from 78 consecutive patients with CAs and 78 demographically matched colonoscopy-negative controls were assayed for anti-H. pylori immunoglobulin G, cagA protein and serum gastrin levels. Multivariate analysis was performed to identify risk factors for colon adenomas. Results: Though prevalence of H. pylori antibodies was not significantly different, the prevalence of cagA protein was significantly higher in patients with adenomas (42.3%) as compared with controls (25.6%, p < 0.03). Mediangastrin levels were significantly higher in patients with CAs (55, 20–975 pg/ml) than in controls (45.2, 23–529 pg/ml) (p < 0.001). Hypergastrinemia (>110 pg/ml) was commoner in patients with CAs than in controls (29.5 vs. 11.5%, p = 0.006) and was the only independent risk factor for adenomas (odds ratio 3.2, 95% CI 1.4–7.5) by multivariate analysis, but not H. pylori infection or cagA positivity. There was a significant association of hypergastrinemia and distal distribution of adenomas (p < 0.002). Conclusions: Our study shows that hypergastrinemia is a risk factor for CAs, especially of the distal colon.


Journal of Clinical Microbiology | 2007

Strategy To Characterize the Number and Type of Repeating EPIYA Phosphorylation Motifs in the Carboxyl Terminus of CagA Protein in Helicobacter pylori Clinical Isolates

Effrosini G. Panayotopoulou; Dionyssios N. Sgouras; Konstantinos S. Papadakos; George V. Papatheodoridis; Andreas Mentis; Athanasios J. Archimandritis

ABSTRACT Cytotoxin-associated gene A (CagA) diversity with regard to EPIYA-A, -B, -C, or -D phosphorylation motifs may play an important role in Helicobacter pylori pathogenesis, and therefore determination of these motifs in H. pylori clinical isolates can become a useful prognostic tool. We propose a strategy for the accurate determination of CagA EPIYA motifs in clinical strains, based upon one-step PCR amplification using primers that flank the EPIYA coding region. We thus analyzed 135 H. pylori isolates derived from 75 adults and 60 children Greek patients. A total of 34 cases were found to be EPIYA PCR negative and were consequently verified as cagA negative by cagA-specific PCR, empty-site cagA PCR, and Western blotting. Sequencing of the remaining 101 PCR-positive amplicons confirmed that an accurate prediction of the number of EPIYA motifs on the basis of size distribution of the PCR products was feasible in all cases. Furthermore, our assay could identify closely related H. pylori subclones within the same patient, harboring different numbers of EPIYA repeats. The prevalence of CagA proteins with three EPIYA motifs (ABC) or four EPIYA motifs (ABCC) was the same within the adult and children groups. However, CagA species with more than four EPIYA motifs were observed exclusively within adults (8.6%), suggesting that CagA-positive strains may acquire additional EPIYA-C motifs throughout adulthood. Our strategy requires no initial cagA screening of the clinical isolates and can accurately predict the number of EPIYA repeats in single or multiple closely related subclones bearing different numbers of EPIYA motifs in their CagA, which may coexist within the same patient.


Journal of Clinical Microbiology | 2009

Phylogenetic Analysis of Human Parvovirus B19 Sequences from Eleven Different Countries Confirms the Predominance of Genotype 1 and Suggests the Spread of Genotype 3b

Judith M. Hübschen; Zefira Mihneva; Andreas Mentis; François Schneider; Yair Aboudy; Zehava Grossman; H Rudich; Kalia Kasymbekova; Inna Sarv; Jasminka Nedeljkovic; Marc C. Tahita; Zekiba Tarnagda; Jean-Bosco Ouédraogo; A. G. Gerasimova; T. N. Moskaleva; Nina T. Tikhonova; Nazibrola Chitadze; Joseph C. Forbi; Adedayo O. Faneye; Jesse A. Otegbayo; Emilie Charpentier; Claude P. Muller

ABSTRACT Phylogenetic analysis of 166 human parvovirus B19 sequences from 11 different countries attributed 91.57% to genotype 1, 5.42% to genotype 3b, and 3.01% to genotype 3a. Very similar viruses of genotype 1 circulated widely in Europe and Israel. Genotype 3b seems to show an increasing spread outside of Africa.


Helicobacter | 2013

Clinical Evaluation of a Ten-Day Regimen with Esomeprazole, Metronidazole, Amoxicillin, and Clarithromycin for the Eradication of Helicobacter pylori in a High Clarithromycin Resistance Area

Sotirios Georgopoulos; Elias Xirouchakis; Beatriz Martinez-Gonzalez; Dionyssios N. Sgouras; Charikleia Spiliadi; Andreas Mentis; Fotini Laoudi

Increasing clarithromycin resistance reduces Helicobacter pylori eradication rates with conventional triple regimens. We evaluated effectiveness and safety of a 10‐day‐quadruple nonbismuth containing regimen, as first‐line treatment or second‐line treatment (after conventional triple) for H. pylori, and assessed impact of antibiotic resistance on treatment success.

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Sotirios Tsiodras

National and Kapodistrian University of Athens

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Angeliki Melidou

Aristotle University of Thessaloniki

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