Coronary Microcirculatory vasoconstriction during ischemia in patients with unstable angina

OBJECTIVE To verify the behavior of coronary microvascular tone during spontaneous ischemia in patients with unstable angina (UA). BACKGROUND In UA, the pathogenetic role of vasoconstriction is classically confined at the stenotic coronary segment. However, microcirculatory vasoconstriction has been also suggested by previous experimental and clinical studies. METHODS The study included 10 patients with UA (recent worsening of anginal threshold and appearance of angina at rest) and single-vessel CAD. Blood flow velocity was monitored by a Doppler catheter in the diseased artery. Transstenotic pressure gradient was monitored by aortic and distal coronary pressure monitoring. Stenosis resistance was calculated as the ratio between pressure gradient and blood flow, microvascular resistance as the ratio between distal pressure and blood flow. Measurements were obtained at baseline, following intracoronary adenosine (2 mg) and during transient ischemia. Aortic and distal coronary pressures were also measured during balloon coronary occlusion. RESULTS Adenosine did not affect stenosis resistance, while it decreased (p , 0.05) microvascular resistance to 52 6 22% of baseline. Angina and ischemic ST segment shift were associated with transient angiographic coronary occlusion in 7 of 10 patients; however, in no case was ischemia associated with interruption of flow. Despite markedly different flow values, distal coronary pressure was similar during adenosine and during spontaneous ischemia (48 6 15 vs. 46 6 20 mm Hg, respectively, NS). During ischemia, a marked increase in the resistance of both coronary stenosis and coronary microcirculation was observed (to 1,233% 6 1,298% and 671% 6 652% of baseline, respectively, p , 0.05). Distal coronary pressure was markedly reduced during balloon coronary occlusion (14 6 7 mm Hg, p , 0.05 vs. both adenosine and ischemia), suggesting the absence of significant collateral circulation. CONCLUSIONS In patients with UA, transient myocardial ischemia is associated with vasoconstriction of both stenotic arterial segment and downstream microcirculation

Metformin and cancer: Technical and clinical implications for FDG-PET imaging

Metformin is the most widely used hypoglycemic agent. Besides its conventional indications, increasing evidence demonstrate a potential efficacy of this biguanide as an anticancer drug. Possible mechanisms of actions seem to be independent from its hypoglycemic effect and seem to involve the interference with key pathways in cellular proliferation and glycolysis. To date, many clinical trials implying the use of metformin in cancer treatment are on-going. The increasing use of (18)F-2-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in cancer evaluation raises a number of questions about the possible interference of the biguanide on FDG distribution. In particular, the interferences exerted by metformin on AMP-activated protein kinase pathway (the cellular energy sensor), on insulin levels and on Hexokinase could potentially have repercussion on glucose handling and thus on FDG distribution. A better comprehension of the impact of metformin on FDG uptake is needed in order to optimize the use of PET in this setting. This evaluation would be useful to ameliorate scans interpretation in diabetic patients under chronic metformin treatment and to critically interpret images in the context of clinical trials. Furthermore, collecting prospective data in this setting would help to verify whether FDG-PET could be a valid tool to appreciate the anticancer effect of this new therapeutic approach

Eficiencia en la asignación de costos en empresa constructora

Tesis (Maestría en Dirección de Negocios) -- Universidad Nacional de Córdoba. Facultad de Ciencias Económicas; Argentina, 2018.El 2016 representó para Argentina el final de un ciclo populista, y con ello el cambio de políticas tanto económicas como sociales. Luego de un año de contracción de la economía y de caída del PBI, el nuevo gobierno debió establecer una estrategia de reactivación y aceleración del crecimiento. Como lo habían hecho gobiernos anteriores, se decidió apostar a la industria de la construcción como motor para lograr esa reacción ya que, según la teoría, el aumento del gasto en obras públicas genera más empleo, con su consecuente aumento del poder adquisitivo y crecimiento del consumo (aumento de la demanda agregada). Complementariamente a largo plazo, mejorar el nivel de infraestructura, genera aumentos de la productividad, la reducción de costos de logística, energéticos y de transporte. El Indicador Sintético de la Actividad de la Construcción (ISAC) muestra la evolución del sector según el comportamiento de la demanda de un conjunto de insumos representativos. La empresa Boetto y Buttilgliengo S.A., objeto de estudio, es una empresa familiar cordobesa con cuarenta años de trayectoria en el rubro de la construcción.Fil: Sambuceti, Antonela. Universidad Nacional de Córdoba. Facultad de Ciencias Económicas; Argentina

¿Quién es el juez justo?

No presenta resumen

Reference Tissue Models for FDG-PET Data: Identifiability and Solvability

A reference tissue model (RTM) is a compartmental approach to the estimation of the kinetic parameters of the tracer flow in a given two-compartment target tissue (TT) without explicit knowledge of the time activity curve (TAC) of tracer concentration in the arterial blood. An \u201cindirect\u201d measure of arterial concentration is provided by the TAC of a suitably chosen one-compartment reference tissue (RT). The RTM is formed by the RT and the TT. In this paper, it is shown that the RTM is identifiable, i.e., the rate constants are uniquely retrievable, provided that a selection criterion for one of the coefficients, which is based on the Logan plot of the RT, is introduced. The exchange coefficients are then evaluated by the application of a Gauss-Newton method, with a regularizing term, accounting for the ill-posedness of the problem. The reliability of the method is validated against synthetic data generated according to realistic conditions, and compared with the full two-compartment model for the TT, here used as \u201cgold standard.\u201d Finally, the RTM is applied to the estimate of the rate constants in the case of animal models with murine cancer cell lines CT26 inoculated

Myocardial blood flow regulation in infarcted patients with stress-induced normalization of negative T waves

The correlation of stress-induced normalization of negative T waves (NTW) with regional myocardial blood flow (MBF) regulation and tissue viability remains still dented