TYPE-ZERO SADDLE-NODE BIFURCATIONS AND STABILITY REGION ESTIMATION OF NONLINEAR AUTONOMOUS DYNAMICAL SYSTEMS

A complete characterization of the stability boundary of a class of nonlinear dynamical systems that admit energy functions is developed in this paper. This characterization generalizes the existing results by allowing the type-zero saddle-node nonhyperbolic equilibrium points on the stability boundary. Conceptual algorithms to obtain optimal estimates of the stability region (basin of attraction) in the form of level sets of a given family of energy functions are derived. The behavior of the stability region and the corresponding estimates are investigated for parameter variation in the neighborhood of a type-zero saddle-node bifurcation value.

Comparative analysis between ventricular and sinoatrial node vascularization in cats

Biasi C., Borelli V., Benedicto H.G., Pereira M.R., Favaron P.O. & Bombonato P.P. 2012. [Comparative analysis between ventricular and sinoatrial node vascularization in cats.] Analise comparativa entre a vascularizacao ventricular e do no sinoatrial em gatos. Pesquisa Veterinaria Brasileira 31(1): 78-82. Setor de Anatomia dos Animais Domesticos e Silvestres, Faculdade de Medicina Veterinaria e Zootecnia, Universidade de Sao Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87, Cidade Universitaria, Sao Paulo, SP 05508-000, Brazil. E-mail: caiobiasi@usp.br The possible existence of interdependence in the blood nutrition of both atrial and ventricular territories has been a subject of concern to cardiologists, mainly related to vascularization of the sinoatrial node and its dependence on just one coronary artery or both, and its relation with the predominance of these vessels in the ventricular vascularization. Therefore, this research aimed evaluated the relation of blood irrigation of the sinoatrial node in relation to the coronary artery predominance in the ventricle vascularization. In doing so, we analyzed 30 hearts of cats without pedigree, males and females, adults of several ages. They were not carrying any heart problems. The hearts were injected by the thoracic aorta with Neoprene Latex 450, stained with red pigment, and then they were dissected. It was found that when there was a prevalence of ventricular vascularization of the left type (63.34%) the sinoatrial node irrigation was predominantly in the dependency of the Ramus proximalis atrii dextri (78.9%) or with less frequency by Ramus proximalis atrii sinister (21.1%). In the ventricular vascularization of the balanced type (33.34%), the pacemaker irrigation was in dependence more often of Ramus proximalis atrii dextri (80%) or with less frequency the nutrition of the sinoatrial node occurred by Ramus proximalis atril sinister (20%). In a single-case, we observed the ventricular vascularization of the right type (3.34%), the pacemaker nutrition was in an exclusive dependence of the Ramus intermedius atril dextri. These results suggest in this species there is no relationship between both the sinoatrial node irrigation and the type of ventricular vascularization, regardless of gender.

Intestinal Lymph-Borne Factors Induce Lung Release of Inflammatory Mediators and Expression of Adhesion Molecules After an Intestinal Ischemic Insult

Background. Intestinal ischemia and reperfusion (I/R) is a documented cause of acute lung injury (ALI) and systemic inflammation. We previously reported that obstruction of thoracic lymphatic flow during intestinal I/R blunts pulmonary neutrophil recruitment and microvascular injury and decreases the systemic levels of tumor necrosis factor. Here, we consider the existence of a gut-lung axis promoting the induction of systemic inflammation, whereby drained intestinal lymph stimulates lung expression of adhesion molecules and matrix components and generation of inflammatory mediators. Material and Methods. Upon administration of anesthesia, male Wistar rats were subjected to occlusion of the superior mesenteric artery for 45 min, followed by 2 h of intestinal reperfusion (I/R); groups of rats were subjected to I/R with or without thoracic lymphatic duct ligation immediately before the procedure. The non-manipulated rats were used to investigate basal parameters. Results. Obstruction of thoracic lymphatic flow before intestinal I/R decreased the ability of cultured lung tissue explants to release IL-1 beta, IL-10, and VEGF. In contrast, lymphatic obstruction normalized the elevated lung expression of PECAM-1 caused by intestinal I/R. On the other hand, lung E-selectin expression was significantly reduced, whereas fibronectin expression and collagen synthesis were not affected. Lymph levels of LTB4 and TXB2 were found to be significantly increased. Conclusions. These data suggest that lymph factors drained from the intestine during ischemic trauma stimulate the lung to generate inflammatory mediators and alter the expression of adhesion molecules. Disturbances in lung homeostasis mediated by lymph might contribute to the spread of inflammatory processes, thereby accounting for the systemic inflammation induced by intestinal I/R. (C) 2012 Elsevier Inc. All rights reserved.

Non-functionant urinary bladder paraganglioma

Introduction: Paragangliomas are rare tumors origined on chromaffin-cells of neural crest and can be located from skull base to pelvis, on sympathetic or parasympathetic paraganglia. They account on less than 0,06% of all urinary bladder tumors, with only few hundreds of cases reported in literature since the first record by Zimmermmann in 1953. Case Report: A 63 year-old woman referring irritative urinary symptoms was submitted to an ultrassonography that disclosed an irregular-shaped nodulation on her bladder. CT confirmed the existence of a nodulation on bladder's anterior wall. Patient had normal levels of urinary catecholamins and Vanilmandelic acid. Tumor was excised and posterior immunohistochemical study revealed it was a paraganglioma. Nowadays, ten months after surgery, patient stills healthy and disease-free. Discussion: Paragangliomas can be classified as functionant or non-functionant, according to its production of cathecolamins, which can cause the same symptom complex of pheocromocytomas. About 10-15% of bladder paragangliomas are malignant, and potential metastasis are more common to lymph nodes, lungs and bones. 131-MIBG iodine cyntilography is the most sensitive method for diagnosis and surgery (transurethral resection or cystectomy) is the best choice for treatment.

Predicting the connectivity of primate cortical networks from topological and spatial node properties

Abstract Background The organization of the connectivity between mammalian cortical areas has become a major subject of study, because of its important role in scaffolding the macroscopic aspects of animal behavior and intelligence. In this study we present a computational reconstruction approach to the problem of network organization, by considering the topological and spatial features of each area in the primate cerebral cortex as subsidy for the reconstruction of the global cortical network connectivity. Starting with all areas being disconnected, pairs of areas with similar sets of features are linked together, in an attempt to recover the original network structure. Results Inferring primate cortical connectivity from the properties of the nodes, remarkably good reconstructions of the global network organization could be obtained, with the topological features allowing slightly superior accuracy to the spatial ones. Analogous reconstruction attempts for the C. elegans neuronal network resulted in substantially poorer recovery, indicating that cortical area interconnections are relatively stronger related to the considered topological and spatial properties than neuronal projections in the nematode. Conclusion The close relationship between area-based features and global connectivity may hint on developmental rules and constraints for cortical networks. Particularly, differences between the predictions from topological and spatial properties, together with the poorer recovery resulting from spatial properties, indicate that the organization of cortical networks is not entirely determined by spatial constraints.

Stability boundary characterization of nonlinear autonomous dynamical systems in the presence of saddle-node equilibrium points

A dynamical characterization of the stability boundary for a fairly large class of nonlinear autonomous dynamical systems is developed in this paper. This characterization generalizes the existing results by allowing the existence of saddle-node equilibrium points on the stability boundary. The stability boundary of an asymptotically stable equilibrium point is shown to consist of the stable manifolds of the hyperbolic equilibrium points on the stability boundary and the stable, stable center and center manifolds of the saddle-node equilibrium points on the stability boundary.