Page 112 - Helicobacter pylori and Gastric Cancer: From Tumor microenvironment to Immunotherapy

Serum pepsinogen levels
Fasting serum was collected from all subjects. The samples were centrifuged immediately at 4 °C and serum stored at −70 °C until used. Serum concentrations of pepsinogen (PG) I and II were measured using a latex-enhanced turbidimetric immunoassay, and the PG I to PG II ratios (PG I/II) were calculated.
Helicobacter pylori detection.
Serum samples from all patients were tested by enzyme linked immunosorbent assay for the presence and concentration of IgG antibodies to H. pylori (HM-CAP; Enteric Products Inc., Westbury, NY). A concentration ≥1.8 was defined as positive (sensitivity 98.7%, specificity 100%).We also employ the gold standard for H. pylori detection by culture. Following collection of gastric biopsy, samples were homogenized and cultured onto Brucella agar supplanted with 5% sheep blood and antibiotics (Vancomycin, Amphotericin B and Trimethoprim). Culture plates were incubated at microaerophilic condition, 37 oC and high humidity for 5-7 days. Organisms were identified as H. pylori based on colony morphology, gram staining and positive oxidase, catalase and urease tests.
Statistical analysis
STATA software (version 10.0; Stata Corp, College Station, TX, USA) was used. Chi-squared test and Fisher’s exact test were applied to evaluate endoscopic, histological, and serological parameters in patients with gastric atrophy. Agreement between endoscopic and histologic evaluations of the grade of gastric atrophy was assessed by determining the weighted kappa value. Factors associated with extensive atrophy were estimated by univariate logistic regression analysis. Covariates showing a significant association with extensive atrophy by the χ2 or t test were included in multiple logistic regression analyses. Odd ratios (ORs) and 95% confidence interval (CI) were calculated to assess the strength of association between variables. A P value < 0.05 was considered statistically significant.
Chapter 5
Chapter 5
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