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
