Determination of free serotonin and its metabolite 5‐HIAA in blood human samples with consideration to pre‐analytical factors

Significant differences have been reported over the years in measuring physiological levels of free circulating serotonin (f5‐HT) in platelet‐poor plasma (PPP). This work shows that there are crucial pre‐analytical factors in sample manipulation that can provoke an artifactual release of 5‐HT from platelets, and that, even when the sample is accurately processed to obtain PPP, f5‐HT levels are approximately 2.8 times higher than those of f5‐HT in blood. An alternative methodology consisting of ex vivo blood microdialysis coupled to high‐performance liquid chromatography–electrochemical detection is proposed and validated. It is considered the most accurate technique to measure physiological circulating f5‐HT and its metabolite 5‐hydroxyindoleacetic acid (f5‐HIAA), owing to its sensitivity (limits of quantification of 0.08 ng/mL) and reliability since there is no sample manipulation. The f5‐HT and f5‐HIAA levels in blood and in PPP were studied in control subjects, hypertensive and end‐stage renal disease patients, who have a deregulated serotonergic system. This work reveals that blood is the best matrix to determine f5‐HT concentrations, and the clinical relevance of the accuracy of f5‐HT determination is discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

A practical procedure for the removal of the phenylethanol moiety from phenylglycinol-derived lactams

Chiral non-racemic bicyclic lactams derived from phenylglycinol have been appointed as key building blocks for the preparation of enantiopure nitrogen compounds. The removal of the chiral inductor leading to substituted piperidones by using air or oxygen in basic media is presented.     

On theT(1)-theorem for the Cauchy integral

The main goal of this paper is to present an alternative, real variable proof of theT(1)-theorem for the Cauchy integral. We then prove that the estimate from below of analytic capacity in terms of total Menger curvature is a direct consequence of theT(1)-theorem. An example shows that theL ^∞-BMO estimate for the Cauchy integral does not follow fromL ² boundedness when the underlying measure is not doubling.     

Graphs with homeomorphically irreducible spanning trees

It is an NP-complete problem to decide whether a graph contains a spanning tree with no vertex of degree 2. We show that these homeomorphically irreducible spanning trees are contained in all graphs with minimum degree at least c√n and in triangulations of the plane. They are nearly present in all graphs of diameter 2. They do not necessarily occur in r-regular or r-connected graphs.     

Orthorhombic Pbcn SnO2 nanowires for gas sensing applications

Pure monocrystalline orthorhombic SnO₂ nanowires decorated and non-decorated with cassiterite SnO₂ nanoclusters are analyzed and compared with pure monocrystalline cassiterite SnO₂. We corroborate the coexistence of both, cassiterite and orthorhombic phases, having a higher growth speed for the cassiterite one, in the obtained nanowires by the evaporation/condensation technique. For both phases, the building blocks are the [SnO₆]^8? octahedron which are forming chains of edge-sharing octahedral along the [0 0 1] direction for the cassiterite phase, while in the orthorhombic phase, chains run in a zigzag fashion and contains four octahedra on each unit of chain instead of two previously reported for orthorhombic material obtained at high pressure conditions as Pbcn SnO₂ orthorhombic structure. Results obtained reveal singular structural characteristics of these synthesized orthorhombic nanowires.