Coronary fluid mechanics in an ageing cardiovascular system

Coronary artery diseases are a leading cause of mortality and are increasingly prevalent with age. However, the large number of age-increasing co-morbidities make difficult to understand the impact of cardiovascular ageing alone on the coronary flow pattern. The present study aims to shed light on the effect of arterial and ventricular ageing on the coronary circulation, which is here studied by means of a validated mathematical model. Forward and backward pressure and flow waves are analysed, as well as their intensity. Results highlight a complex spatiotemporal coronary wave pattern, where intense waves originate from the aorta (particularly in systole) and from the deep myocardium, during both the isovolumic compression and the diastolic phase. The subendocardial viability ratio decreases with age, the total coronary flow is slightly reduced, and the left-ventricular work increases. Consequently, the left-ventricular work per unit of blood flow increases, thus limiting the cell oxygen availability abundance, and therefore increasing the risk of myocardial infarction. Our results highlight a physiological age-induced supply/demand unbalance, which can augment the risk of myocardial ischemia and can contribute to pave the way to other typical coronary pathological processes.     

Synthesis and Chemistry of New Central and Planar Chiral Sulfur-Containing Ferrocenyl Compounds

Abstract

Enantiomerically pure 2-hydroxyalkyl, 2-aminoalkyl and 2-iminoalkyl ferrocenyl p-tolylsulfides are easily prepared in good yields and with complete diastereocontrol from (S)-(2-p-tolylthio)ferrocencarboxyaldehyde. 2-Iminoalkyl ferrocenyl derivatives can be used as ligands in asymmetric catalysis and as starting materials for asymmetric Staudinger reaction.     

Evaluation of methoxy polyethylene glycol‐polylactide diblock copolymers as additive in hypromellose film coating

This paper deals with a new application of diblock methoxy polyethylene glycol‐polylactide block copolymers, a class of synthetic biomaterials largely studied in the pharmaceutical and biomedical fields owing to their favorable properties such as biocompatibility, biodegradability, low immunogenicity, and good mechanical properties. In this work, these materials were evaluated as additives for gastro‐soluble pharmaceutical coating aimed to reduce film stiffness and water permeability. Two copolymers with different polylactide chain lengths were synthesized and characterized in term of molecular weight and solid‐state properties. A series of free films with different hypromellose/copolymers ratio were prepared and characterized in terms of appearance, components miscibility, plasticity, and water vapor permeability. The obtained results demonstrate that copolymers effectively influence hypromellose film properties according to their concentration and molecular weight. Specifically, the addition of the copolymer with a molecular weight of 6.5 kDa in a ratio hypromellose:polymer 5:1, allowed to obtain films with good appearance, improved plasticization, and water permeability properties. For higher molecular weight, copolymer or different ratios was not possible to observe the improvement of all the properties at the same time. The results also make possible to define the critical features to improve in order to use block copolymers as additive in hypromellose film coating. The availability of new water‐soluble additives able to work as plasticizer and moisture sealer in polymeric films represents an important progress not only in the field of pharmaceutical coating but also in that of food coatings, as for example in the formulation of edible films. Copyright © 2013 John Wiley & Sons, Ltd.     

Quaternary Ammonium Polyelectrolytes. V. Amination Studies of Chloromethylated Polystyrene with N,N-Dimethylalkylamines

The amination reactions of chloromethylated polystyrene with N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, and N,N-dimethylhexadecylamine were studied. The physical properties, particularly the solubility properties of the resulting polymers, are influenced by the hydrophobic properties of the long alkyl chain on the N⁺ atoms. The main factor that influences the kinetics of the reactions is the polymersolvent interaction parameter.     

New Aspects of Polymers Containing Quaternary Ammonium Groups

It was established that linear polymers with quaternary ammonium groups are obtained by the reaction of chloromethylated polystyrene (CMPS) with hydroxyalkylic tertiary amines when the amines contain one or two hydroxyl groups, and that crosslinked polymers are obtained with aminoether groups when the amines have three hydroxyl groups, i.e., tris(2-hydroxyethy1)amine. The aminoether units appear by intramolecular rearrangement of quaternary ammonium structural units. Kinetic studies on the synthesis of polymers with quaternary ammonium groups from CMPS, poly(N,N-dimethylamino-ethylmethacrylate), and poly(N,N-dimethylaminopropylacrylamide), were performed. The main factors which influence the kinetics of reactions are steric hindrance of near neighboring groups, hydrophilic effect for hydroxyalkylamines and polymer-solvent interaction.     

Synthesis,binding and fluorescence studies of a new neutral H-bonding receptor for anions based on 3,5-bis(trifluoromethyl)phenylurea

The synthesis and anion binding studies of the new neutral receptor 1,1′-(2,2′-(4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(2-oxoethane-2,1-diyl))bis(3-(3,5-bis(trifluoromethyl)phenyl)urea) (L1) are reported. L1 is a macrocyclic ligand containing the 3,5-trifluoromethylphenylureido-binding fragment attached as a side arm on the tetraazacyclododecane. L1 is soluble in numerous organic solvents; the binding properties of L1 towards several simple anions (G) were investigated by NMR, UV–vis and fluorescence techniques in DMSO and CH₃CN solutions. L1 is able to bind F^? , Cl^?  and AcO^?  in both solvents; in addition, it binds Br^?  in CH₃CN. Fluoride shows the highest constant values in the halide series (F^?  > Cl^?  > Br^? ) and AcO^?  is the most strongly bound among all the anions investigated. L1 is able to signal the presence of the anions in solution by fluorescence change; in the case of acetate, this occurs in the visible range.     

On choosing a reference redox system for electrochemical measurements: a cautionary tale

The potential of a quasi-reference electrode can be determined by introducing an internal reference redox system (IRRS) which comprises either the oxidizable or reducible form of a reversible (and, ideally, outer-sphere) redox couple and then observing the cyclic voltammetric responses. The objective is to choose the IRRS so that the cyclic voltammetric response for the simultaneously present electroactive analyte system (ANS) can be observed independently of the IRRS response. We identify three fundamental paradigms describing the relative positioning of the IRRS and ANS on the potential scale, the operative redox components for the IRRS and ANS, and the starting potential (E _start), reversing potential (E _rev), and ending potential (E _end) for the cyclic voltammetric scan as follows: paradigm A, an optimal paradigm which can produce completely independent cyclic voltammetric responses for the IRRS or for ANS; paradigm B, a less-than-optimal paradigm which can produce an independent cyclic voltammetry (CV) response for the ANS or a mixed response for the IRRS with that response on top of the ANS response; paradigm C, a problematic paradigm that can produce an independent CV response for the IRRS or a mixed response for the ANS with that response on top of the IRRS response; and any mixed response produces a thermodynamically favored redox cross-reaction which couples the IRRS and ANS systems and which can complicate the analysis of the ANS and IRRS responses. The conclusion is that paradigm C is to be avoided.     

Quantification of L‐ergothioneine in whole blood by hydrophilic interaction ultra‐performance liquid chromatography and UV‐detection

A new hydrophilic interaction ultra‐performance LC method was established for the whole blood measurement of L‐ergothioneine. Chromatographic separation was achieved in a fairly short time, less than 4 min, on a 100 × 2.1 mm Acquity UPLC BEH HILIC 1.7 μm column with a mobile phase consisting of a mixture of 100 mmol/L ammonium acetate/ACN/water (5:85:10, v/v/v) that flowed isocratically at 0.250 mL/min. The LOD and the limit of quantification were 3.85 and 11.67 μmol/L, respectively. The method exhibited linearity in a concentration range of 15.63–1000 μmol/L (R² > 0.999). Mean recovery was 96.34% whereas intraassay and interassay precision were 1.52 and 1.82% RSD, respectively. On the whole, the developed method is simple, fast, precise, accurate, and sensitive and may be useful for routine analyses.