RESUMO
Concerning the specificities of a longitudinal study, the trajectories of a subject's mean responses not always present a linear behavior, which calls for tools that take into account the non-linearity of individual trajectories and that describe them towards associating possible random effects with each individual. Generalized additive mixed models (GAMMs) have come to solve this problem, since, in this class of models, it is possible to assign specific random effects to individuals, in addition to rewriting the linear term by summing unknown smooth functions, not parametrically specified, then using the P-splines smoothing technique. Thus, this article aims to introduce this methodology applied to a dataset referring to an experiment involving 57 Swiss mice infected by Trypanosoma cruzi, which had their weights monitored for 12 weeks. The analyses showed significant differences in the weight trajectory of the individuals by treatment group; besides, the assumptions required to validate the model were met. Therefore, it is possible to conclude that this methodology is satisfactory in modeling data of longitudinal sort, because, with this approach, in addition to the possibility of including fixed and random effects, these models allow adding complex correlation structures to residuals.
Assuntos
Animais , Masculino , Camundongos , Trypanosoma cruzi/imunologia , Trypanosoma cruzi/parasitologia , Bioterápicos/antagonistas & inibidores , Soro/imunologia , Soro/parasitologia , Trajetória do Peso do Corpo , Pesos e Medidas Corporais , Anticorpos Antiprotozoários/imunologia , Galinhas , Doença de Chagas/tratamento farmacológico , Ensaio Clínico Controlado Aleatório Veterinário , Camundongos , Antígenos de Protozoários/imunologiaRESUMO
Con el objetivo de conocer la seroprevalencia de la infección por helicobacter pylori (Hp) en niños de una población de la frontera colombo-venezolana, determinanos en sangre anticuerpos IgG contra Hp. Se incluyeron 98 niños, 51 por ciento del sexo masculino y 49 por ciento del sexo femenino. Encontramos IgG contra Hp en el 47 por ciento contra un 53 por ciento de muestras negativas. No hubo diferencias significativas en cuanto al sexo. La mayor frecuencia se observó en los niños de nueve años. Nuestros resultados demuestran que desde temprana edad existe una alta seroprevalencia de la infección por Hp similar a la reportada en otros países en desarrollo.