Improved surgical technique for the establishment of a murine model of aortic transplantation.

Aortic allotransplantation is a reliable procedure to study the evolvement of chronic rejection in mice. The progressive nature of this process in mice is characterized by diffuse and concentric myointimal proliferation which is inevitably associated with variable degrees of luminal constriction. These vascular changes are comparable to those that are witnessed in organ allografts undergoing chronic rejection in humans, underscoring its utility as a model of choice for the study of the development of this lesion. Whilst improved surgical technique has resulted in markedly enhanced graft survival, the results are far from being acceptable. Realizing this limitation, we embarked on developing a modified technique for aortic transplantation which would allow for improved graft survival in mice. A bypass conduit was created by end-to-side anastomosis of a segment of the donor's thoracic aorta into the infrarenal portion of the recipient's abdominal aorta. Using this technique, the graft survival was >98% with evidence in allotransplanted aorta of morphological changes pathognomonic of chronic rejection. On the contrary, no histopathological anomalies were discerned in aortic grafts transplanted across syngeneic animals. This modified surgical approach ameliorates the unacceptably high graft loss associated with earlier techniques, further extending the utility of this model as a tool to study the molecular and cellular mechanisms rudiment to the evolvement of chronic rejection

Marked mitigation of transplant vascular sclerosis in FasL(gld) (CD95L) mutant recipients. I. The role of alloantibodies in the development of chronic rejection

Background. In the acute rejection of allografts, the interaction between Fas (CD95) and its ligand (FasL; CD95L) has been shown to be involved in mediating apoptotic cell death. The role, however, of these molecules in the pathogenesis of transplant vascular sclerosis is as yet undetermined. The present study was therefore designed to address this issue. Material. C3H/HEJ FasL(gld) (FasL-; H2(k)) spontaneously mutant mice were used either as donors or recipients of aortic allografts; wild-type C57BI/6 (B6; H2b) were used as corresponding recipients or donors (n=6/group), respectively. Controls included aortas transplanted across appropriate allogeneic and syngeneic strain combinations. For histopathological evaluations, the grafts were harvested at day 40 after transplantation, at which time, splenocytes and sera were also obtained for mixed leukocyte reaction and complement- mediated microcytotoxicity assays, respectively. Results. Similar to aortas obtained from allogeneic controls, allografts harvested from FasL-→B6 recipients had morphological evidence of chronic rejection characterized by circumferential intimal thickening with partial disruption of the elastic membranes. Correspondingly, heightened antidonor cellular reactivity was also witnessed in these recipients. On the contrary, B6 allografts harvested from the majority of C3H→FasL- recipients exhibited marked preservation of aortic morphology. Although these recipients had diminished antidonor cellular proliferation, the titers of alloantibodies were markedly elevated. Conclusion. The presence of FasL-expressing functional cytotoxic T cells is required for the pathogenesis of transplant vascular sclerosis. The significant reduction and/or absence of chronic rejection with the concomitant retention of antidonor humoral response in C3H FasL- recipients of B6 aortas prompt us to suggest that perhaps posttransplantation vasculopathy is initiated by cell-mediated cytotoxicity with its perpetuation facilitated by alloantibodies

Chlamydia trachomatis Intercepts Golgi-Derived Sphingolipids through a Rab14-Mediated Transport Required for Bacterial Development and Replication

Chlamydia trachomatis are obligate intracellular bacteria that survive and replicate in a bacterial-modified phagosome called inclusion. As other intracellular parasites, these bacteria subvert the phagocytic pathway to avoid degradation in phagolysosomes and exploit trafficking pathways to acquire both energy and nutrients essential for their survival. Rabs are host proteins that control intracellular vesicular trafficking. Rab14, a Golgi-related Rab, controls Golgi to endosomes transport. Since Chlamydia establish a close relationship with the Golgi apparatus, the recruitment and participation of Rab14 on inclusion development and bacteria growth were analyzed. Time course analysis revealed that Rab14 associated with inclusions by 10 h post infection and was maintained throughout the entire developmental cycle. The recruitment was bacterial protein synthesis-dependent but independent of microtubules and Golgi integrity. Overexpression of Rab14 dominant negative mutants delayed inclusion enlargement, and impaired bacteria replication as determined by IFU. Silencing of Rab14 by siRNA also decreased bacteria multiplication and infectivity. By electron microscopy, aberrant bacteria were observed in cells overexpressing the cytosolic negative Rab14 mutant. Our results showed that Rab14 facilitates the delivery of sphingolipids required for bacterial development and replication from the Golgi to chlamydial inclusions. Novel anti-chlamydial therapies could be developed based on the knowledge of how bacteria subvert host vesicular transport events through Rabs manipulation

Ryanodine receptors

Excitation-contraction coupling involves the faithful conversion of electrical stimuli to mechanical shortening in striated muscle cells, enabled by the ubiquitous second messenger, calcium. Crucial to this process are ryanodine receptors (RyRs), the sentinels of massive intracellular calcium stores contained within the sarcoplasmic reticulum. In response to sarcolemmal depolarization, RyRs release calcium into the cytosol, facilitating mobilization of the myofilaments and enabling cell contraction. In order for the cells to relax, calcium must be rapidly resequestered or extruded from the cytosol. The sustainability of this cycle is crucially dependent upon precise regulation of RyRs by numerous cytosolic metabolites and by proteins within the lumen of the sarcoplasmic reticulum and those directly associated with the receptors in a macromolecular complex. In addition to providing the majority of the calcium necessary for contraction of cardiac and skeletal muscle, RyRs act as molecular switchboards that integrate a multitude of cytosolic signals such as dynamic and steady calcium fluctuations, β-adrenergic stimulation (phosphorylation), nitrosylation and metabolic states, and transduce these signals to the channel pore to release appropriate amounts of calcium. Indeed, dysregulation of calcium release via RyRs is associated with life-threatening diseases in both skeletal and cardiac muscle. In this paper, we briefly review some of the most outstanding structural and functional attributes of RyRs and their mechanism of regulation. Further, we address pathogenic RyR dysfunction implicated in cardiovascular disease and skeletal myopathies

Balcones resilientes. Introduciendo seguridad hídrica, energética y alimentaria en viviendas multifamiliares

The urban density in cities is growing, which could favor land use efficiency, mobility and provides an opportunity for other environmental services; for those reasons is expected the increase of homes in high buildings in the coming decades. On the other hand, the urgency of initiatives for adaptation and mitigation to climate change in the cities has led to questions and rethinking for the built environment, as well as alternative proposals moved away from conventions.Considering the large number of families living in medium and high density multifamily homesin most of the world’s cities, the “resilient balconies” project proposes a change in the designand planning of the balcony space; destined to water, energy and food security to create anopportunity for survival face of the uncertain impacts of climate change on cities.Las ciudades vienen experimentado un aumento de densidad urbana, lo cual favorece laeficiencia del suelo, la movilidad y brinda oportunidad para otros servicios medioambientales; por lo que se espera el incremento de viviendas en altura en las próximas décadas.De otro lado, la urgencia de iniciativas para la adaptación y mitigación al cambio climáticoen las urbes viene llevando a cuestionamientos y replanteos para el medio construido,así como propuestas alternativas y alejadas de convencionalismos. Teniendo en cuenta lagran cantidad de familias que viven y vivirán en multifamiliares de mediana y alta densidaden la mayor parte de las ciudades del mundo, el proyecto “balcones resilientes” proponeun cambio en la concepción y diseño del espacio balcón, destinándolo a la seguridad hídrica, energética y alimentaria, pudiendo así crear una oportunidad de supervivencia frente ala incertidumbre de los impactos del cambio climático en las ciudades