Vegetation-environment relatioship based on a life-forms classification in a semiarid region of Tropical Mexico

Taking the view that morphological characteristics represent behavioral strategies of plants to cope with environmental pressures, we defined 18 life-forms, using multivariate classification techniques in a tropical semiarid ecosystem in Central Mexico. A multiple discriminant analysis confirmed the existence of these groups. A null model of random membership of species to life-forms was significantly different from our classification. Vegetation-environment relationships were examined with Detrended Canonical orrespondence Analysis (DCCA). Ordination axes were interpreted mainly be altitude and soil moisture. Response curves of life-forms along these gradients were explored fitting generalized linear models (GLIM's). We believe that the life-forms approach for the study of vegatation-environment relationships is a valid alternative to the traditional species approach usually used in physiological research because: i) life-forms number was found to be an excellent species diversity predictor, ii) this approach enables considerable reduction in the bulk of data without losing ecological information, and iii) life-forms represent ecological strategies per se and, they constitute an index of the number of different ways the desert's resources are utilized

Microbiologia de la otitis cronica en ninos y comparacion de dos tecnicas para la obtencion de la secrecion otica. / Microbiology of chronic otitis in children and comparison of two technics in obtaining otic secretion

Se estudio la concentracion de las immunoglobulinas G y M mas el perfil electroforetico de las proteinas en 14 sueros de ninos con ascesso hepatico amibiano. Todos tenian diferentes grados de perdida de peso y de necrosis hepatica. La concentracion de las proteinas totales del suero estuvo sujeta a diversos factores y resulto con amplias variaciones individuales. Lo mismo se obtuvo cuando se expresaron, en g/dl, los valores de las fracciones que separo la eletroforesis.En cambio, los valores porcentuales dieron un perfil similar para dos los pacientes. Ademas del aumento significativo de las IgG, se encontro uma inversion de la relacion albumina/ globulinas y un aumento de los porcentajes de las fracciones alfa-l, alfa-2 y gamma. Se especula sobre la importancia que pueden tener los mecanismos antienzimas proteoliticas en la evolucion de la lesion que provocan en el higado, las enzimas liberadas por los protozoarios