Los límites del sitio : Una estrategia de muestreo para casos de baja o nula visibilidad arqueológica

En este trabajo se presenta un diseño de muestreo para sitios arqueológicos con baja o nula visibilidad, cuyo objetivo es establecer los límites del asentamiento y evaluar la variabilidad de los hallazgos arqueológicos intrasitio. Los trabajos se realizaron en un área de 10.800 m2 con una cubierta arbórea y de gramíneas. A partir de una pequeña muestra de quince sondeos se calcularon algunos parámetros y se caracterizaron los tipos de hallazgos. El diseño de muestreo se realizó teniendo en cuenta los datos de la muestra inicial, el tamaño mínimo establecido para una unidad o área de ocupación de campamentos de cazadores-recolectores móviles y considerando, además, las probabilidades de que una unidad de muestreo intersecte un sitio, que además contenga un artefacto y que éste sea detectado por el arqueólogoThis paper deals about a sampling design for archaeological sites with low or null visibility, which aims to establish the boundaries of the settlement and assess the variability within intrasite archaeological finds. The research was conducted in an area of 10,800 m2, with tree cover and grass. Some parameters were calculated from a small sample of fifteen test pits and the types of findings were also characterized. The sampling design was based on the initial data sample, the minimum size of mobile hunter-gatherers campsites or settlement areas and the probabilities that a test pit intersect a site, which also contains an artifact and that it can be detected by the archaeologist.Sociedad Argentina de Antropologí

Can a single low-intensity premature stimulus induce ventricular arrhythmias in the normal heart?

Previously, we observed that a single low-intensity premature ventricular stimulation could occasionally induce spontaneous ectopic beats in normal rat hearts. Possible hypothesis for the arrhythmia is that a premature beat can encounter a zone of conduction block to initiate reentry. However, enhanced dispersion of repolarization, a necessary condition for initiation of reentry, is unlikely to be present in normal myocardium. Thus, the main objective of the present study was to perform detailed pace mapping measurements in normal ventricular myocardium with a view to identify pacing sites and critical coupling intervals which could induce spontaneous ectopic beats and to characterize the reentrant circuits

Multienzymatic Stereoselective Reduction of Tetrasubstituted Cyclic Enones to Halohydrins with Three Contiguous Stereogenic Centers

The asymmetric hydrogenation of conjugated tetrasubstituted alkenes with transition-metal catalysts is a challenging reaction, especially for substrates bearing a halide substituent. We describe a two-step multienzymatic reduction of a series of α-halo β-alkyl tetrasubstituted cyclic enones, affording halohydrins with three contiguous stereogenic centers, in good yield and with a high stereoselectivity. The reduction is catalyzed by a stereospecific ene-reductase (OYE2-3 or NemA) and a highly enantioselective alcohol dehydrogenase (ADH). The use of two enantiodivergent ADHs allows the control of the diastereoselectivity. The absolute stereochemical configurations of the products have been determined from the analysis of single-crystal structures (Flack's parameter). The enantiomeric excess (ee) has been determined by derivatization of the products with (R) Mosher's acid. Lastly, we extended our methodology also to a nonhalogenated substrate: the α-methyl ketoisophorone was reduced by two distinct enantiodivergent ene-reductases (flavin mononucleotide- and F 420-dependent), affording each enantiomer of the saturated ketone with ee > 98%

Arrhythmia susceptibility in senescent rat hearts

Cardiovascular disease increases with age as well as alterations of cardiac electrophysiological properties, but a detailed knowledge about changes in cardiac electrophysiology relevant to arrhythmogenesis in the elderly is relatively lacking. The aim of this study was to determine specific age-related changes in electrophysiological properties of the ventricles which can be related to a structural-functional arrhythmogenic substrate. Multiple epicardial electrograms were recorded on the ventricular surface of in vivo control and aged rats, while arrhythmia vulnerability was investigated by premature stimulation protocols. Single or multiple ectopic beats and sustained ventricular arrhythmias were frequently induced in aged but not in control hearts. Abnormal ventricular activation patterns during sinus rhythm and unchanged conduction velocity during point stimulation in aged hearts suggest the occurrence of impaired impulse conduction through the distal Purkinje system that might create a potential reentry substrate

Clinical features and outcomes of elderly hospitalised patients with chronic obstructive pulmonary disease, heart failure or both

Background and objective: Chronic obstructive pulmonary disease (COPD) and heart failure (HF) mutually increase the risk of being present in the same patient, especially if older. Whether or not this coexistence may be associated with a worse prognosis is debated. Therefore, employing data derived from the REPOSI register, we evaluated the clinical features and outcomes in a population of elderly patients admitted to internal medicine wards and having COPD, HF or COPD + HF. Methods: We measured socio-demographic and anthropometric characteristics, severity and prevalence of comorbidities, clinical and laboratory features during hospitalization, mood disorders, functional independence, drug prescriptions and discharge destination. The primary study outcome was the risk of death. Results: We considered 2,343 elderly hospitalized patients (median age 81 years), of whom 1,154 (49%) had COPD, 813 (35%) HF, and 376 (16%) COPD + HF. Patients with COPD + HF had different characteristics than those with COPD or HF, such as a higher prevalence of previous hospitalizations, comorbidities (especially chronic kidney disease), higher respiratory rate at admission and number of prescribed drugs. Patients with COPD + HF (hazard ratio HR 1.74, 95% confidence intervals CI 1.16-2.61) and patients with dementia (HR 1.75, 95% CI 1.06-2.90) had a higher risk of death at one year. The Kaplan-Meier curves showed a higher mortality risk in the group of patients with COPD + HF for all causes (p = 0.010), respiratory causes (p = 0.006), cardiovascular causes (p = 0.046) and respiratory plus cardiovascular causes (p = 0.009). Conclusion: In this real-life cohort of hospitalized elderly patients, the coexistence of COPD and HF significantly worsened prognosis at one year. This finding may help to better define the care needs of this population

Titanium dioxide nanoparticles promote arrhythmias via a direct interaction with rat cardiac tissue

BackgroundIn light of recent developments in nanotechnologies, interest is growing to better comprehend the interaction of nanoparticles with body tissues, in particular within the cardiovascular system. Attention has recently focused on the link between environmental pollution and cardiovascular diseases. Nanoparticles <50 nm in size are known to pass the alveolar¿pulmonary barrier, enter into bloodstream and induce inflammation, but the direct pathogenic mechanisms still need to be evaluated. We thus focused our attention on titanium dioxide (TiO2) nanoparticles, the most diffuse nanomaterial in polluted environments and one generally considered inert for the human body.MethodsWe conducted functional studies on isolated adult rat cardiomyocytes exposed acutely in vitro to TiO2 and on healthy rats administered a single dose of 2 mg/Kg TiO2 NPs via the trachea. Transmission electron microscopy was used to verify the actual presence of TiO2 nanoparticles within cardiac tissue, toxicological assays were used to assess lipid peroxidation and DNA tissue damage, and an in silico method was used to model the effect on action potential.ResultsVentricular myocytes exposed in vitro to TiO2 had significantly reduced action potential duration, impairment of sarcomere shortening and decreased stability of resting membrane potential. In vivo, a single intra-tracheal administration of saline solution containing TiO2 nanoparticles increased cardiac conduction velocity and tissue excitability, resulting in an enhanced propensity for inducible arrhythmias. Computational modeling of ventricular action potential indicated that a membrane leakage could account for the nanoparticle-induced effects measured on real cardiomyocytes.ConclusionsAcute exposure to TiO2 nanoparticles acutely alters cardiac excitability and increases the likelihood of arrhythmic events

Circulación de motivos decorativos en la cerámica de los cazadores-recolectores de la Pampa Deprimida, provincia de Buenos Aires, Argentina

We analyze a set of pottery sherds from seven archaeological sites located in the Pampa Deprimida, all of them with late Holocene chronologies, to discuss the spatial variability of ceramic decoration. As a way to quantify their characteristics and variation we used a component analysis model and statistical techniques. The outcome allows to discriminate a set of similar design or some variation that involve the same attributes or a combination of them and the same decoration techniques, setting up a decorative structure that might have travelled through all these sites. On the other hand, it allows isolating some atypical designs that are present in a few sites or limited to a single one.Se analiza un conjunto de tiestos procedentes de siete sitios de la Pampa Deprimida, cuyas cronologías corresponden al Holoceno tardío, con el objetivo de discutir la variabilidad espacial de la decoración cerámica. Para ello se aplica el modelo de análisis por componentes y se utilizan técnicas estadísticas multivariadas para cuantificar sus características y variabilidad. Los resultados permitieron establecer un conjunto de diseños similares o una variación de estos que involucra los mismos atributos o su combinación, además de las iguales técnicas de decoración, conformando una estructura decorativa que habría circulado por todos estos sitios. Por otra parte, permitieron aislar algunos diseños atípicos que se encuentran restringidos a algunos o a un solo sitio