In vivo Nitrosoproline formation and other risk factors in Costa Rican Children from high-and low-risk areas for gastric cancer

Artículo científico -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1993The hypothesis that intragastric synthesis of N-nitroso compounds (NOC) in early life could play a role in gastric carcinogenesis was tested by applying the N-nitrosoproline (NPRO) test to about 50 children living in high- and low-risk areas for stomach cancer in Costa Rica. The median values of excretion of NPRO and the sum of three nitrosamino acids (micrograms/12 h urine) were 10-20% of those in adults from other geographical high-risk areas for stomach cancer. The urinary NPRO level after proline intake was higher in children from the high-risk area (P < 0.04) and markedly reduced after ingestion of ascorbic acid together with proline (P < 0.05). NPRO levels on the day of proline intake were highly correlated with levels of nitrate excretion (P < 0.001). Mean levels of total NOC in an aqueous (pH 2) extract of cooked beans from the high- and low-risk areas were similar. Acid-catalyzed nitrosation of the extract increased the total NOC concentration up to 1000-fold, but there was no difference between samples from the two areas. About 10% of bean extracts from both areas showed weak direct-acting genotoxicity in Escherichia coli; after acid-catalyzed nitrosation, all samples were genotoxic at similar levels. The diet of children in the low-risk area satisfied recommended levels of intake of energy and most nutrients except riboflavin and retinol equivalents. Diets from the high-risk area were deficient in energy intake and all nutrients except protein and vitamin C. Blood samples were collected from 276 children and young adults from the same areas and analyzed for serum antibodies against Helicobacter pylori. Although very high, no significant difference was found in the prevalence of IgG or IgA antibodies between the two regions.International Agency for Research on Cancer, Lyon, France.Universidad de Costa Rica, Instituto de Investigaciones en SaludUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Helicobater pylori. Is the eradication posible?

Artículo científico -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1999Objetivo: Erradicar H. pylori en pacientes dispepticos de una población de alto riesgo de cancer gástrico Poblacion y metodos: A 174 pacientes dispepticos, de una poblacion de alto riesgo de cancer gastric°, se les determinó la pre valencia de infección por H. pylori y la tasa de erradicaciOn ocho semanas despues de recibir: amoxicilina, subcitrato de bismuto y metronidazol. Resultados: El 98% los pacientes estaban infectados. Se erradica la bacteria solo en el 10.8% de los 83 pacientes que tomaron mas del 75% de los medicamentos. Conclusiones: Las caracteristicas ecológicas y socio-economicas de los pacf-s tropicales en desarrollo hacen que se usen, mal usen y abuse de los antibiOticos, desde la infancia, lo que posibilita la presencia de cepas resistentes a los antibiaticos, especialmente al metronidazol. Este hecho junto con la alta probabilidad de infección y reinfeccion cuestiona el empleo de tratamientos que no hayan sido validados en esos paises. Los esfuerzos deberían dirigirse a conocer el comportamiento de la bacteria y su trasmisión con miras a prevenir la infección y a la búsqueda de una vacuna.Objetive: Elimination H. pylori in dyspeptic patients from a population at high-risk for gastric cancer. Population and methods: In 174 dyspeptic patients from a population at high-risk for gastric cancer, the prevalence rate of H. pylori infection and the perceilt erradication at 8 weeks after treatment with amoxicillin, bismuth subsalicylate and metronidazole were determined. Results: 98% of patients were infected. The bacteria was eliminated in only 10.8% of the 83 patients who took more than 75% of the medicines. Conclusions: Due to ecological and socioeconomical characteristics of tropical countries, frequent use and abuse of antibiotics exists from infancy and this facilitates the presence of strains which are ree)- tant to antibiotics, particularly metronidazole. A .is finding, together with the high probability of infection and reinfection, question the use of treatments that have not been validated in these countries. Efforts should be directed towards determinnig the behaviour of the bacteria and its transmission in order to prevent infection and search for an effective vaccine.Universidad de Costa Rica. Instituto de Investigaciones en SaludUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Exposure to N-nitrosamines and other risk factors for gastric cancer in Costa Rican children

Artículo científico -- Universidad de Costa Rica. Instituto de Investigaciones en Salud, 1991The hypothesis that endogenous chemical nitrosation in the normal stomach in early life could play a crucial role in inducing chronic atrophic gastritis/intestinal metaplasia in later life was tested by applying the N-nitrosoproline (NPRO) test to 12-h urine samples from about 50 children (aged 8-14 years) living in high- and low-risk areas for stomach cancer. The median values of NPRO and the sum of four nitrosamino acids analysed were 0.28-0.84 ag/12 h and 0.75-1.75 tig/12 h, respectively. The NPRO level after proline intake was significantly higher in children from a high-risk area than in those from a low-risk area (p < 0.04), and markedly reduced after ingestion of ascorbic acid and proline (p < 0.05). Urinary nitrate level was lower than that of adults. NPRO levels on the day of proline intake, however, correlated well with nitrate levels (p < 0.001), indicating that children in a high-risk area in Costa Rica have high endogenous nitrosation potential. Blood samples were also collected from about 300 children (aged 7-20 years) and analysed for antibodies against Campylabacter pylori, a suspected gastritis-causing bacteria. About 71% of children in both high- and low-risk areas for stomach cancer had antibodies. In addition, raw and cooked beans, which are consumed very frequently in Costa Rica, were collected from families in both areas and analysed for levels of nitrite/nitrate, total N-nitroso compounds and genotoxicity in the SOS chromotest. Mean levels of total N-nitroso compounds in an aqueous extract (pH 2) of cooked bean samples from high- and low-incidence areas were similar (0.4-0.6 nmol/g of cooked beans). Acid-catalysed nitrosation of the same aqueous extracts produced levels up to 2.4 pmol/g of cooked beans. There was no difference in mean levels of nitrosation-dependent total N-nitroso compounds between samples from the two areas. Only two out of 11 extracts from the low-incidence area and two out of 14 from the high-incidence area showed weak direct genotoxicity. After acid-catalysed nitrosation, all samples were genotoxic at similar levelsUniversidad de Costa Rica. Instituto de Investigaciones en Salud.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Antibodies to Helicobacter pylori and pepsinogen levels in children from Costa Rica: comparison of two areas with different risks for stomach cáncer

Artículo científico -- Universidad de Costa Rica. Instituto de Investigaciones en Salud, 1992In children and adolescents from two areas of Costa Rica with contrasting gastric cancer risks, two factors suspected to be linked to the natural history of the disease were tested: serum antibodies to Helicobacter pylori and serum pepsinogen levels. One hundred fiftyfive subjects from the high-risk area of Turrubares were compared to 127 from the low-risk area of Hojancha. No significant differences were found in the prevalence of IgG or IgA antibodies to Helicobacter pylori between the two regions. The prevalence of IgG was 65.8% in the high-risk area and 72.4 in the lowrisk area, and that of IgA was 43% in both areas. The levels of pepsinogen, especially pepsinogen C, were significantly elevated in subjects with H. pylori antibodies in their serum. The mean levels of pepsinogen C in those negative, positive, and strong positive for H. pylori antibodies were 8.7, 14.3, and 21.1 ng/ml. These findings suggest that H. pyloriassociated gastritis, predominantly of antral localization, is very prevalent in Costa Rican children and adolescents. Such gastritis might be associated with a high prevalence of intestinal metaplasia and a high gastric cancer risk in the inland, but not the coastal rural populations. H. pylori may therefore be an insufficient cause whose role in gastric carcinogenesis is contingent upon the presence of other factors.Universidad de Costa Rica, Instituto de Investigaciones en SaudUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Erradicación de Helicobacter pylori en una población de alto riesgo de cáncer gástrico

Artículo científico -- Universidad de Costa Rica, Instituto de Investigaciones en Salud. 1998Resumen Objetivo: Erradicación de Helicobacter pylori en pacientes dispépticos de una población de alto riesgo de cáncer gástrico. Antecedentes: H. pylori causa gastritis crónica y úlceras pépticas; además se considera un factor de riesgo de cáncer gástrico. El tratamiento es muy controversial por la presencia de cepas resistentes, especialmente en los países en desarrollo. Costa Rica presenta una prevalencia alta de infección por H. pylori y es el país con mayor tasa de mortalidad por cáncer gástrico. Método: En 180 pacientes dispépticos de una población de alto riesgo de cáncer gástrico, en Costa Rica, se determine', por cultivo, tinción y ureasa rápida en las biopsias, la prevalencia de infección por H. pylori, y la tasa de erradicación un mes después de un tratamiento al azar con cimetidina o contra la bacteria (amoxicilina + subsalicilato de bismuto). Resultados: La bacteria estaba presente en el 88,6% de los pacientes. Existe un traslape en la distribución de Ia frecuencia de los niveles de anticuerpos IgG c IgA, de las personas infectadas y no infectadas. Un mes después de finalizar el tratamiento solo se había erradicado is bacteria en 28,9% de los pacientes. Conclusiones: La alta probabilidad de cepas de H. pylori resistentes a los antibióticos y de infección y reinfección en las poblaciones tropicales, exigen evaluar los tratamientos de erradicación, aunque datos hayan tenido éxito en otras poblaciones. Los esfuerzos deben dirigirse a conocer la ecología y vías de trasmisión de Ia bacteria para prevenir la infección: así como a Ia búsqueda de una vacuna. Los niveles de anticuerpos contra H. pylori no sirven para discriminar los pacientes infectados de los no infectadosUniversidad de Costa Rica. Instituto de Investigaciones en Salud.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA