978 resultados para Cardiovascular system - Diseases - Thesis
Resumo:
This research activity studied how the uncertainties are concerned and interrelated through the multi-model approach, since it seems to be the bigger challenge of ocean and weather forecasting. Moreover, we tried to reduce model error throughout the superensemble approach. In order to provide this aim, we created different dataset and by means of proper algorithms we obtained the superensamble estimate. We studied the sensitivity of this algorithm in function of its characteristics parameters. Clearly, it is not possible to evaluate a reasonable estimation of the error neglecting the importance of the grid size of ocean model, for the large amount of all the sub grid-phenomena embedded in space discretizations that can be only roughly parametrized instead of an explicit evaluation. For this reason we also developed a high resolution model, in order to calculate for the first time the impact of grid resolution on model error.
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Alzheimer's disease (AD) is a fatal neurodegenerative condition characterized clinically by progressive memory loss and irreversible cognitive deterioration. It has been shown that there is a progressive degeneration of the brain cholinergic neurons which leads to the appearance of cognitive symptoms of the disease. The aim of this work was the formulation of multifunctional nanocarriers for nasal administration of tacrine-HCl (THA). This route has many advantages; in particular is possible to convey the drug directly to the Central Nervous System, through the olfactory bulb. In particular, were prepared Albumin nanoparticles carrying beta cyclodextrin and two different beta cyclodextrin derivatives (hydroxypropyl beta cyclodextrin and sulphobutylether beta cyclodextrin), and Multifunctional liposomes, prepared using traditional excipients (cholesterol and phosphatidylcholine), partly enriched with α-tocopherol (Toc) and/or polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid) (Ω3). Both nanosystems were characterized in terms of size, Zeta potential and encapsulation efficiency. Were also evaluated their functional properties such as mucoadhesion and permeability, using an ex-vivo assay based on nasal sheep mucosa. On Liposomes were also assessed drug neuronal uptake, cell toxicity, antioxidant and, cytoprotective activity in the human neuronal cell line SH-SY5Y and finally tocopherol trans-membrane diffusion. Both the nanocarriers produced presented excellent properties and a high potential as new systems for CNS-delivery of anti-Alzheimer drugs via the nasal route.
Resumo:
L'insufficienza renale cronica (CKD) è associata ad un rischio cardiovascolare più elevato rispetto alla popolazione generale: fattori come uremia, stress ossidativo, età dialitica, infiammazione, alterazioni del metabolismo minerale e presenza di calcificazioni vascolari incidono fortemente sulla morbosità e mortalità per cause cardiovascolari nel paziente uremico. Diversi studi hanno verificato il coinvolgimento dei progenitori endoteliali (EPC) nella malattia aterosclerotica ed è stato dimostrato che esprimono osteocalcina, marcatore di calcificazione. Inoltre, nella CKD è presente una disfunzione in numero e funzionalità delle EPC. Attualmente, il ruolo delle EPC nella formazione delle calcificazioni vascolari nei pazienti in dialisi non è stato ancora chiarito. Lo scopo della tesi è quello di studiare le EPC prelevate da pazienti con CKD, al fine di determinarne numero e fenotipo. È stato anche valutato l'effetto del trattamento in vitro e in vivo con calcitriolo e paracalcitolo sulle EPC, dato il deficit di vitamina D dei pazienti con CKD: il trattamento con vitamina D sembra avere effetti positivi sul sistema cardiovascolare. Sono stati valutati: numero di EPC circolanti e la relativa espressione di osteocalcina e del recettore della vitamina D; morfologia e fenotipo EPC in vitro; effetti di calcitriolo e paracalcitolo sull’espressione di osteocalcina e sui depositi di calcio. I risultati dello studio suggeriscono che il trattamento con vitamina D abbia un effetto positivo sulle EPC, aumentando il numero di EPC circolanti e normalizzandone la morfologia. Sia calcitriolo che paracalcitolo sono in grado di ridurre notevolmente l’espressione di OC, mentre solo il paracalcitolo ha un effetto significativo sulla riduzione dei depositi di calcio in coltura. In conclusione, il trattamento con vitamina D sembra ridurre il potenziale calcifico delle EPC nell’uremia, aprendo nuove strade per la gestione del rischio cardiovascolare nei pazienti affetti da CKD.
Resumo:
Speeding the VO2 kinetics results in a reduction of the O2 deficit. Two factors might determine VO2 kinetics: oxygen delivery to muscle (Tschakovsky and Hughson 1999) and a muscle 'metabolic inertia' (Grassi et al. 1996). Therefore, in study 1 we investigated VO2 kinetics and cardiovascular system adaptations during step exercise transitions in different regions of the moderate domain. In study 2 we investigated muscle oxygenation and cardio-pulmonary adaptations during step exercise tests before, after and over a period of training. Study 1 methods: Seven subjects (26 ± 8 yr; 176 ± 5 cm; 69 ± 6 kg) performed 4 types of step transition from rest (0-50W; 0-100W) or elevate baseline (25-75W; 25-125W). GET and VO2max were assessed before testing. O2 uptake and were measured during testing. Study 2 methods: 10 subjects (25 ± 4 yr; 175 ± 9 cm; 71 ± 12 kg) performed a step transition test (0 to 100 W) before, after and during 4 weeks of endurance training (ET). VO2max and GET were assessed before and after of ET (40 minutes, 3 times a week, 60% O2max). VO2 uptake, Q and deoxyheamoglobin were measured during testing. Study 1 results: VO2 τ and the functional gain were slower in the upper regions of the moderate domain. Q increased more abruptly during rest to work condition. Q τ was faster than VO2 τ for each exercise step. Study 2 results: VO2 τ became faster after ET (25%) and particularly after 1 training session (4%). Q kinetics changed after 4 training sessions nevertheless it was always faster than VO2 τ. An attenuation in ∆[HHb] /∆VO2 was detectible. Conclusion: these investigations suggest that muscle fibres recruitment exerts a influence on the VO2 response within the moderate domain either during different forms of step transition or following ET.
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In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schrödinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.
Resumo:
The effect of soil incorporation of 7 Meliaceae derivatives (6 commercial neem cakes and leaves of Melia azedarach L.) on C and N dynamics and on nutrient availability to micropropagated GF677 rootstock was investigated. In a first laboratory incubation experiment the derivatives showed different N mineralization dynamics, generally well predicted by their C:N ratio and only partly by their initial N concentration. All derivatives increased microbial biomass C, thus representing a source of C for the soil microbial population. Soil addition of all neem cakes (8 g kg-1) and melia leaves (16 g kg-1) had a positive effect on plant growth and increased root N uptake and leaf green colour of micropropagated plants of GF677. In addition, the neem cakes characterized by higher nutrient concentration increased P and K concentration in shoot and leaves 68 days after the amendment. In another experiment, soil incorporation of 15N labeled melia leaves (16 g kg-1) had no effect on the total amount of plant N, however the percentage of melia derived-N of treated plants ranged between 0.8% and 34% during the experiment. At the end of the growing season, about 7% of N added as melia leaves was recovered in plant, while 70% of it was still present in soil. Real C mineralization and the priming effect induced by the addition of the derivatives were quantified by a natural 13C abundance method. The real C mineralization of the derivatives ranged between 22% and 40% of added-C. All the derivatives studied induced a positive priming effect and, 144 days after the amendment, the amount of C primed corresponded to 26% of added-C, for all the derivatives. Despite this substantial priming effect, the C balance of the soil, 144 days after the amendment, always resulted positive.
Resumo:
One of the current trends in governance and legal development in Russia is aimed at establishing a modern, efficient and internationally harmonised system of safeguards of human rights and civil liberties. A fairly recent addition to this system has been the institution of ombudsman as a public authority specialised in promoting and protecting human rights and civil liberties. The introduction of this institution as well as its formalisation at the constitutional and legislative levels has been increasingly relevant and important, as it raises the dealings between the state and the individual to a new level. As an independent public institution resolving conflicts between citizens and government authorities, the ombudsman makes steps, within the scope of his jurisdiction, to restitute individual rights, and helps to enhance the reputation of government. The present work describes and assesses the birth, development and institutionalization process of the Ombudsman Office in the Russian Federation, at federal and regional levels, with a particular emphasis on the role of international references and cooperation for institution building. Ombudsmen have done a magnificent job in demonstrating value with the resolution of individual and systemic complaints; subsequent improvements to government; and economic savings by mitigating litigation costs.
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In this thesis we focus on optimization and simulation techniques applied to solve strategic, tactical and operational problems rising in the healthcare sector. At first we present three applications to Emilia-Romagna Public Health System (SSR) developed in collaboration with Agenzia Sanitaria e Sociale dell'Emilia-Romagna (ASSR), a regional center for innovation and improvement in health. Agenzia launched a strategic campaign aimed at introducing Operations Research techniques as decision making tools to support technological and organizational innovations. The three applications focus on forecast and fund allocation of medical specialty positions, breast screening program extension and operating theater planning. The case studies exploit the potential of combinatorial optimization, discrete event simulation and system dynamics techniques to solve resource constrained problem arising within Emilia-Romagna territory. We then present an application in collaboration with Dipartimento di Epidemiologia del Lazio that focuses on population demand of service allocation to regional emergency departments. Finally, a simulation-optimization approach, developed in collaboration with INESC TECH center of Porto, to evaluate matching policies for the kidney exchange problem is discussed.
Fault detection, diagnosis and active fault tolerant control for a satellite attitude control system
Resumo:
Modern control systems are becoming more and more complex and control algorithms more and more sophisticated. Consequently, Fault Detection and Diagnosis (FDD) and Fault Tolerant Control (FTC) have gained central importance over the past decades, due to the increasing requirements of availability, cost efficiency, reliability and operating safety. This thesis deals with the FDD and FTC problems in a spacecraft Attitude Determination and Control System (ADCS). Firstly, the detailed nonlinear models of the spacecraft attitude dynamics and kinematics are described, along with the dynamic models of the actuators and main external disturbance sources. The considered ADCS is composed of an array of four redundant reaction wheels. A set of sensors provides satellite angular velocity, attitude and flywheel spin rate information. Then, general overviews of the Fault Detection and Isolation (FDI), Fault Estimation (FE) and Fault Tolerant Control (FTC) problems are presented, and the design and implementation of a novel diagnosis system is described. The system consists of a FDI module composed of properly organized model-based residual filters, exploiting the available input and output information for the detection and localization of an occurred fault. A proper fault mapping procedure and the nonlinear geometric approach are exploited to design residual filters explicitly decoupled from the external aerodynamic disturbance and sensitive to specific sets of faults. The subsequent use of suitable adaptive FE algorithms, based on the exploitation of radial basis function neural networks, allows to obtain accurate fault estimations. Finally, this estimation is actively exploited in a FTC scheme to achieve a suitable fault accommodation and guarantee the desired control performances. A standard sliding mode controller is implemented for attitude stabilization and control. Several simulation results are given to highlight the performances of the overall designed system in case of different types of faults affecting the ADCS actuators and sensors.
Resumo:
The blood-brain barrier (BBB) and the blood-spinal cord barrier (BSCB) separate the brain and the spinal cord from the circulating blood and are important for the maintenance of the CNS homeostasis. They build a physical barrier thereby protecting the CNS from pathogens and toxic agents, and their disruption plays a crucial role in the pathogenesis of several CNS disorders. In this thesis, the blood-CNS-barriers were studied via in vitro models in two case studies for neurodegenerative disorders, in particular Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS). The first model evaluates treatment possibilities of AD using nanotechnology-based strategies. Since the toxic amyloid-β42 (Aβ42) peptide plays a crucial role in the pathogenesis of AD, reduced generation or enhanced clearance of Aβ42 peptides are expected to modify the disease course in AD. Therefore, several Aβ42-lowering drugs like flurbiprofen had been tested in clinical trials, but most of them failed due to their low brain penetration. Here, flurbiprofen was embedded in polylactide (PLA) nanoparticles and its transport was examined in an in vitro BBB model. The embedding of flurbiprofen into the nanoparticles disguised its cytotoxic potential and enabled the administration of higher drug concentrations which resulted in a sufficient transport of the drug across an endothelial cell monolayer. These results demonstrate that non-permeable drugs can be transported efficiently via nanoparticles and that these nanotechnology-based strategies are a promising tool to generate novel therapeutic options for AD and other CNS diseases. rnThe focus of the second project was to investigate the impaired integrity of the BSCB in a mouse model for ALS. About 20% of all familial ALS cases are associated with missense mutations or small deletions in the gene that encodes Cu/Zn-superoxide dismutase 1 (SOD1). To date, the molecular mechanisms resulting in ALS are still unknown, but there is evidence that the disruption of the BSCB is one of the primary pathological events. In both familial and sporadic ALS patients, loss of endothelial integrity and endothelial cell damage was observed, and studies with SOD1 transgenic mice demonstrated that the BSCB disruption was found prior to motor neuron degeneration and neurovascular inflammation. Thus, an in vitro model for ALS endothelial cells was generated which exhibited comparable integrity characteristics and tight junction (TJ) protein expression profiles as isolated primary endothelial cells of the BSCB of SOD1 transgenic mice. In this, an alteration of the βcat/AKT/FoxO1 pathway, which regulates the expression of the TJ protein claudin-5, could be observed. These data furthermore indicate that ALS is a neurovascular disease, and understanding of the primary events in ALS pathogenesis will hopefully provide ideas for the development of new therapeutic strategies. rn
Resumo:
CRF has powerful receptor-mediated cardiovascular actions. To evaluate the precise distribution of CRF receptors, in vitro CRF receptor autoradiography with (125)I-[Tyr(0), Glu(1), Nle(17)]-sauvagine or [(125)I]-antisauvagine-30 was performed in the rodent and human cardiovascular system. An extremely high density of CRF(2) receptors was detected with both tracers in vessels of rodent lung, intestine, pancreas, mesenterium, kidney, urinary bladder, testis, heart, brain, and in heart muscle. In humans, CRF(2) receptors were detected with (125)I- antisauvagine-30 at low levels in vessels of kidneys, intestine, urinary bladder, testis, heart and in heart muscle, while only heart vessels were detected with (125)I-[Tyr(0), Glu(1), Nle(17)]-sauvagine. This is the first extensive morphological study reporting the extremely wide distribution of CRF(2) receptors in the rodent cardiovascular system and a more limited expression in man, suggesting a species-selective CRF receptor expression.
Resumo:
The sedative and cardiovascular effects of rectally administered diazepam (0.6 mg/kg) were compared to placebo in uncooperative children who required sedation during dental treatment. Twelve healthy preschool children, who required amalgam restorations, were treated during two standardized restorative appointments in a double-blind, crossover study. Blood pressure and pulse were obtained during four specified intervals during the appointment. The behavior of the children during the treatment visits was videotaped and later statistically analyzed using a kinesics/vocalization instrument. Behavioral ratings of cooperation were significantly improved during the treatment visit following diazepam. All interfering bodily movements, patient vocalizations and operator commands for the diazepam group were reduced significantly (p≤0.0001). No significant differences were observed for noninterfering behavioral response. Rectally administered diazepam did not alter blood pressure or pulse significantly in these sedated children when compared to the placebo. These findings indicate that rectal diazepam is an effective sedative agent with minimal effect on the cardiovascular system for the management of the young pediatric dental patient.
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A lumped parameter model of the cardiovascular system has been developed and optimized using experimental data obtained from 13 healthy subjects during graded head-up tilt (HUT) from the supine position to [Formula: see text]. The model includes descriptions of the left and right heart, direct ventricular interaction through the septum and pericardium, the systemic and pulmonary circulations, nonlinear pressure volume relationship of the lower body compartment, arterial and cardiopulmonary baroreceptors, as well as autoregulatory mechanisms. A number of important features, including the separate effects of arterial and cardiopulmonary baroreflexes, and autoregulation in the lower body, as well as diastolic ventricular interaction through the pericardium have been included and tested for their significance. Furthermore, the individual effect of parameter associated with heart failure, including LV and RV contractility, baseline systemic vascular resistance, pulmonary vascular resistance, total blood volume, LV diastolic stiffness and reflex gain on HUT response have also been investigated. Our fitted model compares favorably with our experimental measurements and published literature at a range of tilt angles, in terms of both global and regional hemodynamic variables. Compared to the normal condition, a simulated congestive heart failure condition produced a blunted response to HUT with regards to the percentage changes in cardiac output, stroke volume, end diastolic volume and effector response (i.e., heart contractility, venous unstressed volume, systemic vascular resistance and heart rate) with progressive tilting.
Resumo:
A large body of empirical research shows that psychosocial risk factors (PSRFs) such as low socio-economic status, social isolation, stress, type-D personality, depression and anxiety increase the risk of incident coronary heart disease (CHD) and also contribute to poorer health-related quality of life (HRQoL) and prognosis in patients with established CHD. PSRFs may also act as barriers to lifestyle changes and treatment adherence and may moderate the effects of cardiac rehabilitation (CR). Furthermore, there appears to be a bidirectional interaction between PSRFs and the cardiovascular system. Stress, anxiety and depression affect the cardiovascular system through immune, neuroendocrine and behavioural pathways. In turn, CHD and its associated treatments may lead to distress in patients, including anxiety and depression. In clinical practice, PSRFs can be assessed with single-item screening questions, standardised questionnaires, or structured clinical interviews. Psychotherapy and medication can be considered to alleviate any PSRF-related symptoms and to enhance HRQoL, but the evidence for a definite beneficial effect on cardiac endpoints is inconclusive. A multimodal behavioural intervention, integrating counselling for PSRFs and coping with illness should be included within comprehensive CR. Patients with clinically significant symptoms of distress should be referred for psychological counselling or psychologically focused interventions and/or psychopharmacological treatment. To conclude, the success of CR may critically depend on the interdependence of the body and mind and this interaction needs to be reflected through the assessment and management of PSRFs in line with robust scientific evidence, by trained staff, integrated within the core CR team.
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Close similarities of various physiological parameters makes the pig one of the preferred animal models for the study of human diseases, especially those involving the cardiovascular system. Unfortunately, the use of pig models to study diseases such as viral hemorrhagic fevers and endotoxic shock syndrome have been hampered by the lack of the necessary immunological tools to measure important immunoregulatory cytokines such as tumor necrosis factor (TNF). Here we describe a TNF-bioassay which is based on the porcine kidney cell line PK(15). Compared to the widely used murine fibroblastoid cell line L929, the PK(15) cell line displays a 100-1000-fold higher sensitivity for porcine TNF-alpha, a higher sensitivity for human TNF-alpha, and a slightly lower sensitivity for murine TNF-alpha. Using a PK(15) bioassay we can detect recombinant TNF-alpha as well as cytotoxic activity in the supernatants of lipopolysaccharide (LPS)-activated porcine monocytes at high dilutions. This suggests that the sensitivity of the test should permit the detection of TNF in biological specimens such as pig serum.