Sarraf Nejad A, Hoodei E, Siavoshi F, Maserrat S, Jadali Z, Shahrestani T,
Volume 59, Issue 4 (9 2001)
Abstract
Helicobacter pylori (H.pylori) is the most prominent causative agent of gastroduodenal diseases all over the world. Other manifestations such as urticaria and coronary heart diseases, also are suspected to be induced by H.pylori. Non invasive methods are preferred for diagnosis and ELISA, because of its reliability, speed, sensitivity and specificity is widely preferred as diagnostic tool. Previously we have used IFA, and here, we report an indirect ELISA technique for H.pylori diagnosis. First, 9 strains, of H.pylori isolated from biopsies, were cultured, and the soluble crude antigen was used to coat ELISA plates. Antigen concentration and conjugated antiserum dilution were optimised using checker board method. In this study the gold standard was: rapid urease test, culture and direct smear. Patient serum dillution and the cut-off value was determind, using 22 negative and 30 positive confirmed samples according to ROC curve and the results were compared with a commercial kit. The sensitivity and specificity of this method were 93.2 percent and 95.4 percent respectively. A commercial ELISA Kit, was used and compared simultaneously. The sensitivity and specificity were 87.8 percent and 73 percent respectively. Therefore, regarding the acceptable sensitivity and specificity, ease of work of ELISA, being economical and non-invasive, it can be employed in diagnosis of H.pylori infection and also in epidemiological studies.
Zavarreza J, Doosti M, Ariabarzin Sh, Soleymani S, Siavoshi F, Maserrat S,
Volume 65, Issue 1 (5 2008)
Abstract
Background: Helicobacter pylori (H. pylori) is one of the major causes of peptic ulcer, gastritis and gastric cancer. This bacterium has a special lipopolysaccharide (LPS), which is responsible for its pathogenesis and its high resistance against gastric acid and escape from the human immune system. This property makes it a target for further research and diagnostic goals. In this study, the extraction of the LPS and separation from the outer membrane is required.
Methods: The LPS was extracted from the outer membrane, or envelope, of H. pylori obtained from patients suffering from gastritis, gastric ulcer and gastric cancer. LPS extraction was performed using the proteinase K method. SDS-PAGE and silver staining were applied to investigate the electrophoretic pattern of the LPS. This pattern was compared with that of E. coli serotype O111:B4 and Salmonella serotype ATCC 14028.
Results: The extracted LPS has a ladder-shaped electrophoretic pattern and the bands are located in three groups: high, medium and low molecular weights.
Conclusion: The distribution of the bands of the ladder-shaped electrophoretic pattern is caused by the different number of oligosaccharide chains associated with the LPS. The high molecular weight bands represent S-LPS and the low molecular weight bands represent the R-LPS, which lacks the O-chain.
