Developmental regulation of mouse brain monomeric acetylcholinesterase.

Acetylcholinesterase (AChE) molecular forms were studied during mouse brain development. Mouse embryos expressed a monomeric (G1) and a tetrameric (G4) AChE form. Our results indicate that G4 AChE expressed at embryonic day (ED) 9 and ED15 could be purified by acridinium-Sepharose chromatography and shared similar biochemical and kinetic properties with the adult form. However, the G1 form expressed at either embryonic stage did not bind to acridinium, was not inhibited by excess substrate, and possessed higher K(m) and lower Vmax values than the adult G1 form. Two peripheral anionic binding site inhibitors, fasciculin and propidium, had a significantly lower affinity for the monomeric form at ED9. Results are discussed in terms of the biological significance of the embryonic G1 form, and its resemblance to the AChE activity found, associated with the senile plaques present in the brains of Alzheimer's patients.

[Biological success in osseointegrated implants]. / Exito biológico en implantes oseointegrados.

Long term research results initiated by Dr. P. I. Branemark in 1965 and before, had widely demonstrated that with an adequate biomaterial, a phenomenon of biological acceptance from maxillary bone occurs, configurating a real bone healing, obtaining an intimate bonding between this alive tissue and the implant, which will last under function. Nevertheless, for this bio-physiological step happens and remain, there are many necessary factors named biological and biomechanical principles, and they command and are the responsibles of the osseointegration success.