Modelo experimental de infeccion por Helicobacter pylori en el raton. Estudio del dano gastrico producido por indometacina / Experimental model of infection of Helicobacter pylori in the mouse. A study of gastric damage caused by indomethacin

INTRODUCTION: The action of non-steroidal anti-inflammatory drugs (NSAIDs) on the Helicobacter Pylori (Hp) infected mucosa is a matter of debate. Some authors consider them to cause additive iatrogeny whilst others attribute a purportedly protective action to them. The development of on experimental animal model could help clarify this phenomenon. OBJECTIVES: 1--To develop an animal model of Hp gastric infection. 2--To evaluate the aggressiveness of NSAIDs in this model. MATERIALS AND METHODS: Male 6 month old BALC/C mice weighing 38 g were studied. Pylori Hp infection was ruled out. On three occasions, in the same week, 18 mice were inoculated intra-gastrically with 0.6 ml of Hp culture broth (brain-heart infusion) containing 1 x 10 8-1 x 10 9 CFU/ml. Another group of mice were inoculated with sterile saline. After two months the mice were killed and their stomachs studied. They were divided into groups: a) 6 Hp negative control mice. b) 8 Hp negative mice with prior intra-peritoneal injection of 25 mg/Kg indomethacin (24 hs.) c) 8 mice inoculated with Hp with indomethacin. d) 8 mice inoculated with Hp, without indomethacin. The stomachs were opened along the greater curvature and photographed macroscopically in order to map the necrotic area. The antrums were biopsied to test for urease and separate antrum and body specimens were send for staining with Warthin-Starry H & B and histopathology. RESULTS: All the mice inoculated with Hp acquired the infection. The necrotic area was larger in Group B: 55.5 +/- 7.87 mm than in Group C: 15 +/- 1.82 mm P < 0.00019. HISTOLOGY: Group A: normal mucosa. Group B: extensive coagulation necrosis and focal erosions. Group C: ulcers with inflammatory infiltrate and smaller necrotic area, presence of Hp on the surface epithelium. Group D: no ulcers, Hp present. CONCLUSION: An animal model of Hp infection was successfully developed Hp infection could play a potentially protective role against indomethacin aggression in the mouse.

Stable isotope techniques for the detection of Helicobacter pylori infection in clinical practice. 13C-urea breath test in different experimental conditions

The (13)C-UBT has been demonstrated to be a reliable method for the evaluation of Helicobacter pylori infection. The aim of our work is to determine the cut-off point of the (13)C-UBT for samples collected as gas or collected in a solution of triethanolamine. For this purpose, patients fasted for at least 6 hours were able to collect basal samples before the administration of 65 mg of (13)C-urea solution. Breath samples were taken 10,30 and 60 minutes after the administration of the labeled solution. All the samples were collected in gas collectors and in glass vials containing 1 ml of a 7 per cent triethanolamine solution. The cut-off points for gas collected samples were established in 4.0 per cent and for 10, 30 and 60 minutes samples, respectively, while for the samples, collected in triethanolamine solution, cut-off points were established in 5.0 per cent, for the 10 minutes samples, in 3.5 per cent for the 30 minutes samples and 4.7 per cent for the 60 minutes samples. We found that this test has a sensitivity of 100 per cent and a specificity of 100 per cent for H. pylori detection in both experimental conditions, when multiple breath samples are taken. If we considered only the 30 minutes time, sensitivity and specificity diminish for the gas collected samples. We conclude that the collection of breath samples in triethanolamine solution allows a better differentiation between H. pylori infected and non infected patients than gas collected samples.