[Diagnostic assessment of knowledge and competencies in medical students at the end of the second year of medical school: the challenge of building an airplane while it's flying].

Introduction: In Latin America there is almost no published information about knowledge retention and formative assessment of competencies in medical students, during medical school training and curricular changes.

Objective: To assess knowledge level and clinical competencies in medical students at the end of the second year in a new curriculum.

Methods: Observational, cross-sectional study in UNAM Faculty of Medicine students.

[Impact of problem-based learning on the cognitive processes of medical students].

The problem based learning (PBL) method was conceived as a teaching strategy to be applied in different areas or disciplines, thus several universities adopted it, among which was the Universidad Nacional Autónoma de México, best known as UNAM. The Faculty of Medicine of UNAM implemented this innovative teaching method of medicine for its learner-centered educational method tendency (patient-centered practice). This method develops also several abilities in the students, such as active and significant learning, seeking and data selection and autoanalysis and synthesis, knowledge integration of, mind's logic for the detection and solution of problems, among others.

[Signaling pathways involved in megakaryopoiesis].

Hematotoxicology has been studied with less interest than other fields associated with atmospheric pollution. There is limited knowledge about on the effects that certain atmospheric pollutants may provoke in the blood and bone marrow. Suspended particle pollution has become an area of scientific inquiry due to the contaminants adhering to its surface.