MEF

Cell death is a crucial process during development, homeostasis and immune regulation of multicellular organisms, and its dysregulation is associated with numerous pathologies. Cell death is often induced upon pathogen infection as part of the defense mechanism, and pathogens have evolved strategies to modulate host cell death. In this review, we will discuss the molecular mechanisms and physiological relevance of four major types of programmed cell death, namely apoptosis, necrosis, autophagic cell death and pyroptosis.

Mutations in the presenilin genes (PS) account for most cases of familial Alzheimer's disease. PS contain the active site of the γ-secretase complex that cleaves within the transmembrane domain of β-amyloid precursor protein (APP). Full-length PS undergoes regulated endoproteolysis to produce fragments that comprise the active form of PS. The “presenilinase” responsible for endoproteolysis is unknown but may be the same presenilin-dependent γ-secretase activity that cleaves APP. To investigate the mechanism of endoproteolysis, we examined sequence specificity at the cleavage site and tested whether PS dimers are important for endoproteolysis as well as γ-secretase activity. No single point mutation, or a double mutation M292D/V293K, was able to completely abolish endoproteolysis and all mutants supported γ-secretase activity. When wtPS1 was co-expressed with either M292D/V293K or D257A, it was unable to restore normal endoproteolysis to either mutant. Lack of transcleavage by wtPS1 suggests that PS1 endoproteolysis occurs via intramolecular cleavage and does not require dimerization.

Revista Ciencias Técnicas Agropecuarias Universidad Agraria de La Habana paneque@isch.edu.cu ISSN (Versión impresa): 1010-2760 CUBA ... 2008 Miguel Herrera Suárez / Ciro E. Iglesias Coronel / Omar González Cueto / Elvis López Bravo / Ángel Sánchez ...

This document presents partial results of a much broader research project that has recognized historical and technical aspects pertaining to a set of 34 historic brick arch bridges, 20 of which still exist, all with diverse geometric characteristics and singular dimensions. The methodological process is exposed as carried out with one of them and conclusions are presented, which can be extended to almost the totality of the cases studied for the purpose of offering new analysis alternatives to professionals interested in the rehabilitation and
conservation of the Colombian architectural and engineering patrimony.