Peptides for Coating TiO2 Implants: An In Silico Approach.

Titanium is usually used in the manufacturing of metal implants due to its biocompatibility and high resistance to corrosion. A structural and functional connection between the living bone and the surface of the implant, a process called osseointegration, is mandatory for avoiding prolonged healing, infections, and tissue loss. Therefore, osseointegration is crucial for the success of the implantation procedure. Osseointegration is a process mediated by bone-matrix progenitor cells' proteins, named integrins. In this study, we used an in silico approach to assemble and test peptides that can be strategically used in sensitizing TiO2 implants in order to improve osseointegration. To do so, we downloaded PDB structures of integrins α5ß1, αvß3, and αIIbß3; their biological ligands; and low-cost proteins from the Protein Data Bank, and then we performed a primary (integrin-protein) docking analysis. Furthermore, we modeled complex peptides with the potential to bind to the TiO2 surface on the implant, as well as integrins in the bone-matrix progenitor cells. Then we performed a secondary (integrin-peptide) docking analysis. The ten most promising integrin-peptide docking results were further verified by molecular dynamics (MD) simulations. We recognized 82 peptides with great potential to bind the integrins, and therefore to be used in coating TiO2 implants. Among them, peptides 1 (GHTHYHAVRTQTTGR), 3 (RKLPDATGR), and 8 (GHTHYHAVRTQTLKA) showed the highest binding stability during the MD simulations. This bioinformatics approach saves time and more effectively directs in vitro studies.

O deixar-se cair e a estrutura do ato suicida / Dejarse caer y la estructura del acto suicida / Letting oneself fall and the structure of the suicidal act

O trabalho tem como propósito discutir o suicídio e sua estrutura de ato, adotando como pre-missa que a satisfação presente na autopunição é indutora da perspectiva lacaniana sobre pas-sagem ao ato e acting out. Para a construção deste estudo, tomou-se como base a metapsico-logia da melancolia em sua diferenciação do luto, o mito de Ájax, de Sófocles, e o caso freudi-ano da Jovem Homossexual, para explorar o posicionamento do Eu e do objeto como engrena-gem intrínseca ao ato suicida. Dado que Ajax se deixa cair sobre a espada e a Jovem Homosse-xual sobrevive após se atirar de uma ponte, o que se percebe é que há na queda o desfecho de algo que não mais seria suportável. É neste movimento que a constituição do Eu é atravessada e o sujeito lança-se para fora da cena, ao se identificar ao objeto a, em uma última saída. (AU)

The purpose of this work is to discuss the suicide and its structure of the act, taking as its premise that the satisfaction present in self-punishment introduces the Lacanian perspective on passage to the act and acting out. For the construction of this study, the metapsychology of melancholia in its differentiation from the mourning process, the myth of Ajax, of Sophocles, and the Freudian case about the Young Homosexual Woman were used as basis, to explore the positioning of the Ego and the object as intrinsic gear to the suicidal act. Given that Ajax lets himself fall on the sword and the Young Homosexual Woman survives after throwing herself off a bridge, what is noticeable is that there is in the fall the outcome of something that would no longer be bearable. It is in this movement that the egoic constitution is transposed and the subject throws himself out of the scene, by identifying himself with object a, in a last exit. (AU)