Zakia Abid

A simple multiplex PCR assay for diagnosing virulent Helicobacter pylori infection in human gastric biopsy specimens from subjects with gastric carcinoma and other gastro-duodenal diseases

Aim:  To evaluate and develop a multiplex polymerase chain reaction (PCR) assay for diagnosing and specific identification of virulent Helicobacter pylori strains and their main virulence genes cagA, cagE, cagT, vacA and hrgA.

Anti-unlcer and antimicrobial activities of sodium selenite against Helicobacter pylori: in vitro and in vivo evaluation.

Abstract We examined sodium selenite, an inorganic selenium supplement, for its ulcer healing properties and antimicrobial activity against gastric pathogen Helicobacter pylori. Minimum inhibitory concentrations (MIC) were determined using disk diffusion and flow cytometry. The studies were performed over a concentration range of 1 μg/ml to 500 μg/ml sodium selenite. Mild activity was seen at 10 μg/ml and 50 μg/ml, a moderate response at 100 μg/ml and strong response at 500 μg/ml with a MIC value of 10 μg/ml. The compound was found to be active at low pH without any resistance after 10 passages. Flow cytometry data showed a characteristic shift of the viability peak in comparison with the control, thereby confirming the bactericidal effects of sodium selenite. Sodium selenite administered in Wistar rats, pre-ulcerated with naproxen and infected with H. pylori, showed ulcer healing and anti-H. pylori activity at a concentration range of 10–50 μg/rat; however concentrations of 100 μg/rat and 500 μg/rat were found to be toxic in the in vivo studies. In conclusion, sodium selenite shows both ulcer healing and anti-H. pylori activity at a low concentration (10 μg/rat) without toxicity.

Antibacterial and ulcer healing effects of organoselenium compounds in naproxen induced and Helicobacter pylori infected wistar rat model.

Aim of the present study was to evaluate in vitro toxicity and in vivo antibacterial, anti-inflammatory, antiulcer, and antioxidant activities of two organoselenium compounds, selenocystine (SeCys) and ebselen (Ebs). The study was conducted in experimentally induced ulcers in rodent model infected with Helicobacter pylori (H. pylori). In vitro toxicological studies on normal splenic lymphocytes revealed that SeCys and Ebs were non-toxic to the cells even at 100 μM concentration. Antibacterial activity was observed at 500 μg/mL concentration of either of the compounds against H. pylori. In vivo studies after treatment with SeCys and Ebs (500 μg/kg/day) resulted in significant reduction in ROS production and inhibition of lipid peroxidation in gastric tissue. The antioxidant and anti-inflammatory activities of both the compounds were also confirmed by their ability to lower GSH reduction, to induce the expression of antioxidant genes such as GPx-4, and MnSOD and to suppress inflammatory genes namely COX-2, TNF-α and TGF-β. In addition, the immunomodulatory activity of both the compounds was evident by enhance of the CD4 levels and maintenance of the IgG, IL-6 and IL-10 levels. Persistent treatment (500 μg/kg, for 28 days) with both the compounds showed considerable (p<0.05) ulcer healing property supporting its role in gastro protection. In conclusion, the results of our study suggest that both SeCys and Ebs possess broad spectrum of activities without any potential toxicity.

Relevance of Helicobacter pylori genotypes in gastric pathology and its association with plasma malondialdehyde and nitric oxide levels

Persistent infection with Helicobacter pylori confers an increased risk of peptic ulceration and gastric adenocarcinoma. Reactive oxygen and nitrogen species play a crucial role in the progression from normal gastric mucosa to cancer. The aim of the present study was to investigate the plasma malondialdehyde and nitric oxide levels in H. pylori related gastroduodenal diseases and associate their levels with gastric pathology and genotypes of H. pylori. Malondialdehyde and nitric oxide levels in plasma samples of 250 subjects were spectrophotometrically determined. Subsequently, genotypic and histopathological assessment was performed in gastric biopsies obtained during endoscopy. The levels of MDA and NO exceeded in subjects infected with genotype-1 of Hp than those with other genotypes suggesting more precise interaction of highly virulent strains of Hp in eliciting severe tissue damage. In conclusion, the study demonstrates close relationship between the plasma malondialdehyde and nitric oxide levels, gastric histopathology and genotypes of H. pylori.

OL-030 Synergistic interplay between Helicobacter pylori virulence genes and host COX-2 and iNOS enhances the risk of premalignant and malignant lesions

Background and Aim: H. pylori (Hp) strains vary in their carcinogenic potential. Both host factors and bacterial factors have been postulated to contribute to the variable outcome. Over expression of host COX-2 and iNOS has been implicated in the development of gastric carcinoma. Furthermore, the link between genotypes in relation to COX-2 and iNOS expression and disease status needs to be determined. Therefore the present study addressed to identify Hp-bearing hosts who are at greatest risk of developing precancerous lesions. Methods: A total of 240 subjects with various gastric disorders were screened. Genotyping based on cagA, cagE, cagT, vacA signal region and hrgA genes of Hp was performed using DNA from gastric biopsies. Expression of COX-2 and iNOS was assessed by RT-PCR and immunoblotting. Histological scoring of antral and corpus biopsies for the presence precancerous lesions was done. Results: The genotype cagA+/cagE+/cagT+/hrgA+/vacAs1 showed high prevalence 177 (73.7%). Among which 81.1% had overt gastric disorders whereas 46% subjects had less severe gastric disease. Histology revealed presence of atrophy in 52% vs 18%, IM in 32% vs 9% and dysplasia in 20% vs 4% respectively (Statistically significant at p < 0.01). RT-PCR and immunoblotting data showed high expression patterns of COX-2 and iNOS in overt gastric disorders than with less severe gastrointestinal disorders. Conclusion: Genotype cagT+ve/hrgA+ve/cagA+ve/cagE+ve/ vacAs1+ve and heightened expression levels of COX-2 and iNOS have higher differentiating and predictive value for the development of severe disease manifestations. This suggests that Hp induced gastric inflammatory reaction to be influenced by multiple factors, and probably results from the synergistic effect of bacterial virulence and host factors, which work together in a complex way causing various diseases in the host.