The origin of the saline waters in the Villafáfila lakes (NW Spain). A hydrogeological, hydrochemical, and geophysical approach.

Villafáfila lakes are a natural reserve included in the intergovernmental RAMSAR agreements for conservation of wetlands, with special interest for their brackish-saline waters. These lakes are located at the western margin of the Duero basin, whose aquifer system has no evaporitic rocks upstream. Understanding the origin of the lake's salinity, the groundwater circulation and the distribution of the brackish-saline waters in the area is important not only for the preservation and management of the natural reserve, but for human water consumption as well. Three types of waters have been identified according to their chemical composition. Type 1 are calcium-bicarbonate fresh waters identified in the local recharge areas (surrounding hills); Type 2 are mixed waters dominated by sodium and chloride-bicarbonate, identified at the toe of the hills; Type 3 are brackish to saline sodium-chloride waters from the lakes, springs and boreholes. Time domain electromagnetic (TDEM) profiles have revealed the existence of a basement elevation that forces brackish regional groundwater flow to rise. Radiocarbon age of regional groundwaters points to residence times of 20-30 Ky. Villafáfila lakes are through-flow lakes nourished by meteoric waters (direct precipitation and shallow groundwaters) as deduced by stable isotopes (δ18OH2O, δDH2O), while the solutes are provided by ascendant deep groundwater flows in the lakes bottom and in the surrounding area. Sulphate stable isotopes (δ18OSO4=; δ34SSO4=) suggest that deep groundwaters have been in contact with Triassic and Cenozoic evaporites. Below the lake's bottom there is a brine (TDS = 27 g/L) contained within the lake-sediment aquitard that is concentrated by evaporation in the vadose zone and by salt recycling. A salinity inversion has been observed below the brine. The lack of saline crusts on the lake's bottom is favored by the SW outflow of the brine.

Europatitan eastwoodi, a new sauropod from the lower Cretaceous of Iberia in the initial radiation of somphospondylans in Laurasia.

The sauropod of El Oterillo II is a specimen that was excavated from the Castrillo de la Reina Formation (Burgos, Spain), late Barremian-early Aptian, in the 2000s but initially remained undescribed. A tooth and elements of the axial skeleton, and the scapular and pelvic girdle, represent it. It is one of the most complete titanosauriform sauropods from the Early Cretaceous of Europe and presents an opportunity to deepen our understanding of the radiation of this clade in the Early Cretaceous and study the paleobiogeographical relationships of Iberia with Gondwana and with other parts of Laurasia. The late Barremian-early Aptian is the time interval in the Cretaceous with the greatest diversity of sauropod taxa described in Iberia: two titanosauriforms, Tastavinsaurus and Europatitan; and a rebbachisaurid, Demandasaurus. The new sauropod Europatitan eastwoodi n. gen. n. sp. presents a series of autapomorphic characters in the presacral vertebrae and scapula that distinguish it from the other sauropods of the Early Cretaceous of Iberia. Our phylogenetic study locates Europatitan as the basalmost member of the Somphospondyli, clearly differentiated from other clades such as Brachiosauridae and Titanosauria, and distantly related to the contemporaneous Tastavinsaurus. Europatitan could be a representative of a Eurogondwanan fauna like Demandasaurus, the other sauropod described from the Castrillo de la Reina Formation. The presence of a sauropod fauna with marked Gondwananan affinities in the Aptian of Iberia reinforces the idea of faunal exchanges between this continental masses during the Early Cretaceous. Further specimens and more detailed analysis are needed to elucidate if this Aptian fauna is caused by the presence of previously unnoticed Aptian land bridges, or it represents a relict fauna from an earlier dispersal event.

Molecular mechanisms underlying synergistic adhesion of sickle red blood cells by hypoxia and low nitric oxide bioavailability.

The molecular mechanisms by which nitric oxide (NO) bioavailability modulates the clinical expression of sickle cell disease (SCD) remain elusive. We investigated the effect of hypoxia and NO bioavailability on sickle red blood cell (sRBC) adhesion using mice deficient for endothelial NO synthase (eNOS) because their NO metabolite levels are similar to those of SCD mice but without hypoxemia. Whereas sRBC adhesion to endothelial cells in eNOS-deficient mice was synergistically upregulated at the onset of hypoxia, leukocyte adhesion was unaffected. Restoring NO metabolite levels to physiological levels markedly reduced sRBC adhesion to levels seen under normoxia. These results indicate that sRBC adherence to endothelial cells increases in response to hypoxia prior to leukocyte adherence, and that low NO bioavailability synergistically upregulates sRBC adhesion under hypoxia. Although multiple adhesion molecules mediate sRBC adhesion, we found a central role for P-selectin in sRBC adhesion. Hypoxia and low NO bioavailability upregulated P-selectin expression in endothelial cells in an additive manner through p38 kinase pathways. These results demonstrate novel cellular and signaling mechanisms that regulate sRBC adhesion under hypoxia and low NO bioavailability. Importantly, these findings point us toward new molecular targets to inhibit cell adhesion in SCD.

Nitric oxide reduces sickle hemoglobin polymerization: potential role of nitric oxide-induced charge alteration in depolymerization.

We previously demonstrated that inhaling nitric oxide (NO) increases the oxygen affinity of sickle red blood cells (RBCs) in patients with sickle cell disease (SCD). Our recent studies found that NO lowered the P(50) values of sickle hemoglobin (HbS) hemolysates but did not increase methemoglobin (metHb) levels, supporting the role of NO, but not metHb, in the oxygen affinity of HbS. Here we examine the mechanism by which NO increases HbS oxygen affinity. Because anti-sickling agents increase sickle RBC oxygen affinity, we first determined whether NO exhibits anti-sickling properties. The viscosity of HbS hemolysates, measured by falling ball assays, increased upon deoxygenation; NO treatment reduced the increment. Multiphoton microscopic analyses showed smaller HbS polymers in deoxygenated sickle RBCs and HbS hemolysates exposed to NO. These results suggest that NO inhibits HbS polymer formation and has anti-sickling properties. Furthermore, we found that HbS treated with NO exhibits an isoelectric point similar to that of HbA, suggesting that NO alters the electric charge of HbS. NO-HbS adducts had the same elution time as HbA upon high performance liquid chromatography analysis. This study demonstrates that NO may disrupt HbS polymers by abolishing the excess positive charge of HbS, resulting in increased oxygen affinity.

Guayaquil en 1842: Rocafuerte y la epidemia de fiebre amarilla / Colección Rescate / Guayaquil in 1842: Rocafuerte and the epidemic of yellow fever

Narra las causas y consecuencias de la epidemia de fiebre amarilla desatada en Guayaquil en 1842. Expone el número de víctimas por día, entre otros indicadores epidemiológicos; la evolución de la peste; y las medidas sanitarias adoptadas por el entonces presidente de la república Don Vicente Rocafuerte, para combatirla. Es un estudio histórico de los hechos desde el punto de vista clínico/terapéutico...