Equine exercise electrocardiogram : standardized lungeing test

Dissertação de Mestrado Integrado em Medicina Veterinária

Adaptação da Florida Affect Battery à população portuguesa

Dissertação de Mestrado, Neurociências Cognitivas e Neuropsicologia, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2016

Activité physique et récompense : impact de la leptine et de la signalisation STAT3 dans les neurones dopaminergiques

La course d’endurance active le système de récompense (SR) et est reliée aux comportements de recherche alimentaire. L’influence de la leptine sur l’activité physique (AP) volontaire est bien documentée d’un point de vue physiologique, mais très peu en termes d’impact hédonique. La leptine inhibe l’effet récompensant lié à la consommation de nourriture et joue un rôle semblable pour d’autres types de stimuli. La leptine s’arrime à la forme longue du récepteur à la leptine (Leprb) situé sur les neurones à dopamine (DA) et GABA de l’aire tegmentale ventrale (ATV) dans le mésencéphale. Signal transducer and Activator of Transcription 3 (STAT3) est un facteur de transcription important de la cascade de signalisation de la leptine. La phosphorylation de STAT3 n’est détectée que dans une parcelle des neurones DA positifs pour le Leprb, conférant aux neurones DA STAT3-spécifiques des caractéristiques uniques. Nous avons généré un modèle murin invalidé pour STAT3 sélectivement dans les neurones DA (STAT3DAT-KO). La première expérience consistait à évaluer les paramètres métaboliques de base de notre modèle en utilisant les chambres métaboliques Comprehensive Lab Animal Monitoring System (CLAMS), incluant l’activité ambulatoire, le ratio d’échanges respiratoires (RER) et la production de chaleur. Les STAT3DAT-KO sont hyperactives, démontré par une activité locomotrice augmentée, mais aucune variation entre les deux groupes n’est observée pour le RER et la production de chaleur, en plus d’un gain de poids identique. Une stratégie de récupération ciblant la réinsertion de STAT3 dans les neurones DA du système mésolimbique normalise l’AP anciennement plus élevée des STAT3DAT-KO à celle des contrôles, suivant l’accès libre à une roue d’exercice (RE) pour une durée de 4 semaines, suivant l’accès libre à une roue d’exercice (RE) pour une durée de 4 semaines. L’injection d’un psychostimulant (agoniste du récepteur DA de type 1 (D1R), le Chloro-APB-Hydrobromide (SKF 82958)) reflète une fonction dopaminergique réduite chez les STAT3DAT-KO. Un test de recherche compulsive de nourriture révèle une suppression de la prise alimentaire chez les deux groupes expérimentaux. Nous démontrons pour la première fois que la motivation alliée à la course d’endurance, indépendamment de la régulation de la prise alimentaire par la leptine, est dépendant d’une signalisation leptine-STAT3 amoindrie dans les neurones DA du système mésolimbique, révélant STAT3 comme élément clé dans la régulation du tonus dopaminergique et des propriétés récompensantes de l’AP.

Phosphodiesterase 6 generates intracellular cGMP microdomains in the native endothelium

Endothelial cells (EC) are essential regulator of vascular homeostasis through the generation and release of various bioactive agents, including nitric oxide (NO). NO modulates several vascular functions such as vascular tone and permeability, through the stimulation of soluble guanylate cyclase (sGC) leading to the production of cGMP. Conversely, phosphodiesterases (PDEs) are enzymes metabolizing cyclic nucleotides (cGMP and cAMP) and are therefore major regulatory players for cGMP and cAMP signalling pathways. Although ECs are the main source of NO, little is known on the endothelial NO-cGMP signalling pathway and cellular outcomes. It was then hypothesized that a specific population of cGMP-phosphodiesterases allows ECs to stabilize cGMP levels despite the elevated production of NO. Expression of cGMP-phosphodiesterases was initially studied in resistance mesenteric arteries from mice. PDE5 and PDE6 were both found at mRNA and protein levels in native arteries but PDE6 is not found in cultured ECs. Interestingly, subcellular distributions of both enzymes were distinct. PDE5 appeared to be homogeneously distributed whilst PDE6 catalytic subunits (PDE6 and PDE6) showed a preferential staining in the perinuclear region. These results suggest that PDE6 might be involved in the regulation of cGMP microdomains. Based on these findings, a mathematical model was developed. Simulations of dynamic cGMP levels in ECs support the notion of cGMP microdomains dependent on PDE6 expression and localization. In the absence of PDE6, application of NO either as a single bolus or repetitive pulses led to a homogeneous increase in cGMP levels in ECs despite PDE5 homogeneous distribution. However, PDE6 subcellular targeting to the perinuclear membrane generated a cGMP-depleted perinuclear space. The findings from this study provide the first evidence of the expression and specific intracellular distribution of PDE6 in native endothelial cells that strongly support their involvement in the generation of cGMP microdomains

Preservation of Nitric Oxide Availability as Nitrite and Nitrosothiols

Nitric Oxide (NO) has been known for long to regulate vessel tone. However, the close proximity of the site of NO production to “sinks” of NO such as hemoglobin (Hb) in blood suggest that blood will scavenge most of the NO produced. Therefore, it is unclear how NO is able to play its physiological roles. The current study deals with means by which this could be understood. Towards studying the role of nitrosothiols and nitrite in preserving NO availability, a study of the kinetics of glutathione (GSH) nitrosation by NO donors in aerated buffered solutions was undertaken first. Results suggest an increase in the rate of the corresponding nitrosothiol (GSNO) formation with an increase in GSH with a half-maximum constant EC50 that depends on NO concentration, thus indicating a significant contribution of ∙NO2 mediated nitrosation in the production of GSNO. Next, the ability of nitrite to be reduced to NO in the smooth muscle cells was evaluated. The NO formed was inhibited by sGC inhibitors and accelerated by activators and was independent of O2 concentration. Nitrite transport mechanisms and effects of exogenous nitrate on transport and reduction of nitrite were examined. The results showed that sGC can mediate nitrite reduction to NO and nitrite is transported across the smooth muscle cell membrane via anion channels, both of which can be attenuated by nitrate. Finally, a 2 – D axisymmetric diffusion model was constructed to test the accumulation of NO in the smooth muscle layer from reduction of nitrite. It was observed that at the end of the simulation period with physiological concentrations of nitrite in the smooth muscle cells (SMC), a low sustained NO generated from nitrite reduction could maintain significant sGC activity and might affect vessel tone. The major nitrosating mechanism in the circulation at reduced O2 levels was found to be anaerobic and a Cu+ dependent GSNO reduction activity was found to deliver minor amounts of NO from physiological GSNO levels in the tissue.

Give Us This Day

GIVE US THIS DAY is a collection of poetry grounded in the lyrical tradition that speaks to the conflicting need for structure and the inherent desire to be free. It focuses on those moments of rupture, when the structure, whether physical, emotional, psychological or political, is broken. The title poem sets the tone for the collection, capturing the idea that today is all one can truly know. Throughout the five sections of the collection, one comes to understand a complex family story, where right and wrong is blurred in the reality of existence. The sections, representing various parts of the day, are a parallel to the individual stories, speaking to the idea that a single day contains both times of light and darkness, similar to a life. The collection takes place in several cityscapes from Moscow to Delhi, Washington, D.C. to Miami. There are correlations drawn between familial settings and political unrest and tension. Often the political atmosphere is alluded to and drawn into context through the use of intimate personal vignettes. In contrast to the urban noise, there is pervasive natural imagery of gardens and tropical locales which mimic the physical life cycle, climaxing in the blossom.

Theoretical investigation of intra- and inter-cellular spatiotemporal calcium patterns in microcirculation

Microcirculatory vessels are lined by endothelial cells (ECs) which are surrounded by a single or multiple layer of smooth muscle cells (SMCs). Spontaneous and agonist induced spatiotemporal calcium (Ca2+) events are generated in ECs and SMCs, and regulated by complex bi-directional signaling between the two layers which ultimately determines the vessel tone. The contractile state of microcirculatory vessels is an important factor in the determination of vascular resistance, blood flow and blood pressure. This dissertation presents theoretical insights into some of the important and currently unresolved phenomena in microvascular tone regulation. Compartmental and continuum models of isolated EC and SMC, coupled EC-SMC and a multi-cellular vessel segment with deterministic and stochastic descriptions of the cellular components were developed, and the intra- and inter-cellular spatiotemporal Ca2+ mobilization was examined.^ Coupled EC-SMC model simulations captured the experimentally observed localized subcellular EC Ca2+ events arising from the opening of EC transient receptor vanilloid 4 (TRPV4) channels and inositol triphosphate receptors (IP3Rs). These localized EC Ca2+ events result in endothelium-derived hyperpolarization (EDH) and Nitric Oxide (NO) production which transmit to the adjacent SMCs to ultimately result in vasodilation. The model examined the effect of heterogeneous distribution of cellular components and channel gating kinetics in determination of the amplitude and spread of the Ca2+ events. The simulations suggested the necessity of co-localization of certain cellular components for modulation of EDH and NO responses. Isolated EC and SMC models captured intracellular Ca2+ wave like activity and predicted the necessity of non-uniform distribution of cellular components for the generation of Ca2+ waves. The simulations also suggested the role of membrane potential dynamics in regulating Ca2+ wave velocity. The multi-cellular vessel segment model examined the underlying mechanisms for the intercellular synchronization of spontaneous oscillatory Ca2+ waves in individual SMC. ^ From local subcellular events to integrated macro-scale behavior at the vessel level, the developed multi-scale models captured basic features of vascular Ca2+ signaling and provide insights for their physiological relevance. The models provide a theoretical framework for assisting investigations on the regulation of vascular tone in health and disease.^

A graduate piano recital : an analytical study

The purpose of this thesis is to provide a historical and musical analysis that illustrates characteristic features of musical compositions from the Baroque, Classical, Romantic, and Twentieth century styles. The structural analysis of the pieces reveal the evolution in the musical expression regarding line, texture, form, and the technical skills employed by the composers through polyphonic, homophonic, and twelve-tone procedures. The works of this recital represent four different styles: The prelude and fugue among the important forms of the Baroque style; the sonata embodying the principles of balance and unity of the Classical style; the etude and waltz as representative of the Romantic style; and the nocturne as an illustration of the transformation of the melody, harmony, and rhythm in the music of the 20thcentury.