73 research outputs found
Endocardial-mesenchymal transition underlies fusion of the conotruncal ridges during embryonic cardiac outflow tract septation
The embryonic cardiac outflow tract (conotruncus) is a single tubular chamber that connects the right ventricle with the aortic arch arteries. It contains two opposite, long and helical mesenchymal cushions covered by endocardial cells (conotruncal ridges). Conotruncal division (septation) gives rise to the adult right and left outflows together with the aortic and pulmonary valves. It takes place by fusion of the two opposite ridges and formation of the conotruncal septum. Although the participation of neural crest cells in septation is well established, the mechanism of fusion of the conotruncal ridges remains unknown. Defects in fusion have been shown to produce bicuspid aortic valve, the most prevalent human congenital cardiac malformation, in a hamster model.
Three fusion mechanisms have been proposed to operate during embryonic development: epithelial adhesion, epithelial apoptosis and epithelial-mesenchymal transition (EMT). The first mechanism entails the expression of adhesion molecules and the maintenance of the identity of cells in contact, whereas in the other two, epithelial cells covering the fusing structures disappear by apoptosis or by transforming into mesenchymal cells. The objective of this study is to elucidate the mechanism involved in the fusion of the conotruncal ridges. Immunofluorecence techniques were used in ED 11-12 hamster embryos.
The results indicate that the mechanism of EMT, but not epithelial adhesion or apoptosis, is involved in the process of fusion of the conotruncal ridges. The EMT mechanism associated with conotruncal septation seems to be uncoupled from the process of formation of the endocardial cushions, which takes place at early stages. With these results, we can raise the hypothesis that defects in the EMT process may lead to different morphological types of bicuspid aortic valve.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech. This study was supported by P10-CTS-6068 (Junta de AndalucĂa), CGL2014-52356-P and CGL2017-85090-P (Ministerio de EconomĂa y Competitividad), contract UMAJI75 (Junta de AndalucĂa, European Social Fund), and Universidad de Málaga
The anatomical components of the cardiac outflow tract of the bichir, polypterus senegalus. Evolutionary significance
El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013.Anatomical Record, Volume 296, Special Feature — 1: P-077.In chondrichthyans and actinopterygians, the outflow tract of the heart, namely, the
cardiac portion intercalated between the ventricle and the ventral aorta, consists of two
anatomical components: conus arteriosus and bulbus arteriosus. In chondrichthyans and
extant representatives of phylogenetically ancient actinopterygian groups, the conus and
bulbus are well-developed in size, whereas in most teleosts, the bulbus is markedly
larger than the conus. Current knowledge about the cardiac outflow tract of the
polypteriformes is scarce and highly contradictory, a fact that contrasts with their
crucial phylogenetic position at the source of the actinopterygian lineage. In fact, it
remains uncertain whether they have a bulbus at the arterial pole of the heart. The
present study aimed to elucidate the anatomical arrangement of the cardiac outflow tract
of the bichir in an attempt to improve our understanding of the evolution of the
vertebrate heart. We examined the hearts from 12 bichirs using histochemical and
immunohistochemical techniques. Our findings showed that the outflow tract of the
bichir consists of two components, namely, a long conus arteriosus, largely composed
of myocardial tissue and furnished with a variable number of valves at its luminal side,
and a very short, elastin rich bulbus arteriosus, devoid of myocardium. The bulbus has
an arterial-like histological composition. However, it differs from the aorta because it
has a thicker wall, shows a different arrangement of the histological elements, is
covered by the epicardium and is crossed by coronary arteries. The present observations
are consistent with the notion that the conus arteriosus and the bulbus arteriosus have
coexisted from the beginning of the jawed vertebrate radiation. This is of particular
interest, because there is evidence that the bulbus arteriosus, which is a second heart
field derivative, is homologous with the intrapericardial portions of the aorta and
pulmonary artery of birds and mammals.Proyecto CGL2010-16417/BOS; Fondos FEDER
Stochastic Comparisons of Two-Units Repairable Systems
We consider two models of two-units repairable systems: cold standby system
and warm standby system. We suppose that the lifetimes and repair times of the
units are all independent exponentially distributed random variables. Using
stochastic orders we compare the lifetimes of systems under different
assumptions on the parameters of exponential distributions. We also consider a
cold standby system where the lifetimes and repair times of its units are not
necessarily exponentially distributed
PROMESA, Puerto Rico’s Recipe for Disaster
PROMESA was signed with the purpose of helping the island’s economy recover from its crippling indebtedness. But three years later, the law has caused financial and social instability. Although, PROMESA grants Puerto Rico the right to file for bankruptcy, the effects of the law are worsening the island’s situation. Austerity measures, high costs, migration and a deeper economic recession are drowning the island.
Link to Capstone: https://medium.com/@cristina.oruna/promesa-puerto-ricos-recipe-for-disaster-1eadde7b671
Implementation of key biosecurity measures in Spanish broiler houses to reduce Campylobacter prevalence: hygienic barrier and training of farm personnel
Efficacy of biosecurity measures in Spanish broiler farms to prevent thermophilic Campylobacter colonization
ICN as Network Infrastructure for Multi-Sensory Devices: Local Domain Service Discovery for ICN-based IoT Environments
Information Centric Networking (ICN) is an emerging research topic aiming at shifting the Internet from its current host-centric paradigm towards an approach centred around content, which enables the direct retrieval of information objects in a secure, reliable, scalable, and efficient way. The exposure of ICN to scenarios other than static content distribution is a growing research topic, promising to extend the impact of ICN to a broader scale. In this context, particular attention has been given to the application of ICN in Internet of Things (IoT) environments. The current paper, by focusing on local domain IoT scenarios, such as multi-sensory Machine to Machine environments, discusses the challenges that ICN, particularly Interest-based solutions, impose to service discovery. This work proposes a service discovery mechanism for such scenarios, relying on an alternative forwarding pipeline for supporting its core operations. The proposed mechanism is validated through a proof-of-concept prototype, developed on top of the Named Data Networking ICN architecture, with results showcasing the benefits of our solution for discovering services within a collision domain. © 2017 Springer Science+Business Media New Yor
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