[Alimentary factors and gastric cancer: design of a hospital based case-control study]. / Factores alimentarios y cáncer gástrico: diseño de un estudio caso-control de base hospitalaria.

One of the most widely used design in etiologic research is the case-control study. In the present work the methodology used in the design of a case-control study, performed in a hospital setting, which objectives was to verify etiological hypothesis related with food-intake and gastric adenocarcinoma and 234 controls from the population--188 selected through a randomized selection on the phone book and 46 following neighborhood criteria--are studied. The methodology and the development of the field work are described, with a special interest in the possible bias incurred during its design and development.

[Immune response to hepatitis B vaccine produced with genetic engineering]. / Respuesta inmunitaria a la vacuna contra la hepatitis B obtenida por ingeniería genética.

With the aim of evaluating the immune response obtained after the administration of the three standard doses of Hepatitis B vaccine obtained by recombinant DNA techniques (Engerix B) and the factors that may have an influence in it, we have studied 537 subjects belonging to different risk groups. The ratio of non-responders to the vaccine has been. We have found significant differences (p less than 0.001) when comparing the mean titers obtained amongst the groups of studied. We have observed a higher percentage amongst the non-responders in men, although there are not statistically significant differences between sexes. We compare the results obtained with those published by other groups.