Solvatochromism in urea/water and urea-derivative/water solutions.

This work reports the experimental measurements of solvent acidity (SA), basicity (SB), and solvent dipolarity and polarizability (SPP) for water solutions with urea (U) and its molecular derivatives, monomethyl-urea (MU), 1,3-dimethyl-urea (DMU) and tetramethyl-urea (TMU). These solvatochromic parameters are applied to understanding the variation of indexes of refraction and densities and other physico-chemical properties reported for these solutions. These properties are well correlated to the SA, SB, and SPP solvent parameters of these solutions. As a result, from the characterization of the physico-chemical properties, one can infer that urea and its molecular derivatives are mainly modifiers in the structure of liquid water. The solvatochromic parameters indicate the possible existence of different mechanisms in the denaturation process of proteins in these urea/water solutions.

Prediabetes y pronóstico clínico de los pacientes con cardiopatía isquémica y revascularización coronaria percutánea / Prediabetes and coronary artery disease: Outcome after revascularization procedures

Objetivo: Determinar si la prediabetes, a largo plazo, se asocia a un mayor riesgo de eventos cardiovasculares en pacientes con cardiopatía isquémica y revascularización coronaria percutánea. Método: Cohortes retrospectivo. De los procedimientos de revascularización realizados durante 2010 se seleccionaron aquellos sin diagnóstico de diabetes y con determinación de hemoglobina glucosilada. Se constituyeron 2 grupos: prediabetes (5,7-6,5%) y control (< 5,7%). Se registraron variables demográficas, clínicas e intervencionistas. Los objetivos de estudio fueron mortalidad, ingresos hospitalarios, infarto de miocardio (IM) y procedimientos de revascularización. Resultados: Los sujetos de estudio fueron 132 (hombres 82,6%; edad 65,26 ± 12,46). No se encontraron diferencias significativas en las variables demográficas, clínicas ni intervencionistas. La prevalencia de prediabetes fue 40,2%. El 64,1% de los casos de revascularización se debieron a IM con elevación de ST. Tras un seguimiento de 42,3 ± 3,6 meses no se encontraron diferencias entre prediabetes y control en mortalidad total: 5,4% vs 1,9% (riesgo relativo [RR]: 2,86, intervalo de confianza del 95% [IC 95%]): 0,27-30,44, p = 0,56), mortalidad no cardiovascular: 2,7% vs 1,9% (RR: 1,43, IC 95%: 0,93-22,18, p = 0,79), ingresos de cualquier causa: 19% vs 25% (RR: 1,13, IC 95%: 0,73-1,73, p = 0,57), IM: 3% vs 1% (RR: 4,28, IC 95%: 0,46-39,52; p = 0,30) ni revascularización de la lesión tratada: 3% vs 6% (RR: 0,70, IC 95%: 0,18-2,61, p = 0,72). Conclusiones: En pacientes sometidos a revascularización coronaria la presencia de prediabetes, definida según valores de hemoglobina glucosilada, no se asocia a un incremento de eventos cardiovasculares a largo plazo (AU)

Objective: To assess the long-term association between prediabetes and an increased risk of cardiovascular events in patients with coronary artery disease and percutaneous coronary intervention (PCI). Methods: A retrospective cohort study. We searched our database to identify all PCI procedures performed in 2010. Patients with no diabetes and HbA1c measurement in the index hospitalization were enrolled and divided into two groups based on HbA1c value: 5.7-6.5% for prediabetes and <5.7% for controls. Demographic, clinical, and procedure-related variables were recorded. Study endpoints were mortality, hospital admissions, myocardial infarction (MI), and revascularization procedures. Results: The study population consisted of 132 subjects (82.6% males, age: 65.26 ± 12.46 years). No difference was found as regards distribution of demographic, clinical, and procedure-related variables. A majority (64.1%) of PCI procedures were performed for ST-segment elevation MI. Prevalence of prediabetes was 40.2%. After a mean follow-up period of 42.3 ± 3.6 months, no differences were found in outcomes between the prediabetes and control groups in total mortality (5.4% vs 1.9%; relative risk [RR] 2.86, 95% confidence interval [95% CI] 0.27-30.44; P = .56), non-cardiovascular mortality (2.7% vs 1.9%; RR 1.43, 95% CI 0.93-22.18; P = .79), hospital admissions (19% vs 25%; RR 1.13, 95%CI 0.73-1.73; P = .57), MI (3% vs 1%; RR 4.28, 95%CI .46-39.52; P = .30), or target lesion revascularization (3% vs 6%); RR .70, 95%CI .18-2.61; P = .72). Conclusions: Prediabetes, as determined by HbA1c (5.7%-6.5%), is not associated with long-term adverse cardiovascular outcomes in patients with CAD and PCI (AU)

Prediabetes and coronary artery disease: Outcome after revascularization procedures.

OBJECTIVE: To assess the long-term association between prediabetes and an increased risk of cardiovascular events in patients with coronary artery disease and percutaneous coronary intervention (PCI). METHODS: A retrospective cohort study. We searched our database to identify all PCI procedures performed in 2010. Patients with no diabetes and HbA1c measurement in the index hospitalization were enrolled and divided into two groups based on HbA1c value: 5.7-6.5% for prediabetes and <5.7% for controls. Demographic, clinical, and procedure-related variables were recorded. Study endpoints were mortality, hospital admissions, myocardial infarction (MI), and revascularization procedures. RESULTS: The study population consisted of 132 subjects (82.6% males, age: 65.26 ± 12.46 years). No difference was found as regards distribution of demographic, clinical, and procedure-related variables. A majority (64.1%) of PCI procedures were performed for ST-segment elevation MI. Prevalence of prediabetes was 40.2%. After a mean follow-up period of 42.3 ± 3.6 months, no differences were found in outcomes between the prediabetes and control groups in total mortality (5.4% vs 1.9%; relative risk [RR] 2.86, 95% confidence interval [95% CI] 0.27-30.44; P=.56), non-cardiovascular mortality (2.7% vs 1.9%; RR 1.43, 95% CI 0.93-22.18; P=.79), hospital admissions (19% vs 25%; RR 1.13, 95%CI 0.73-1.73; P=.57), MI (3% vs 1%; RR 4.28, 95%CI .46-39.52; P=.30), or target lesion revascularization (3% vs 6%); RR .70, 95%CI .18-2.61; P=.72). CONCLUSIONS: Prediabetes, as determined by HbA1c (5.7%-6.5%), is not associated with long-term adverse cardiovascular outcomes in patients with CAD and PCI.

Síndrome poslesión cardíaca: pericarditis traumática: a propósito de un caso / Post-cardiac injury syndrome. Post-traumatic pericarditis: apropos of a case

La pericarditis postraumática se incluye dentro de los síndromes poslesión cardíaca. Este síndrome es un proceso inflamatorio que afecta al pericardio, la pleura, o ambos, secundario a un infarto de miocardio, a un traumatismo torácico o a una cirugía cardíaca. Las características clínicas incluyen el dolor torácico de perfil pericardítico, fiebre y elevación de los reactantes de fase aguda. Generalmente responde de manera satisfactoria al tratamiento con antiinflamatorios no esteroideos y corticoides, pero la falta de pruebas diagnósticas puede llevar a estudios innecesarios o tratamientos inadecuados con posibles efectos secundarios. Se presenta el caso de un hombre joven que evolucionó favorablemente tras la instauración del tratamiento apropiado(AU)

Temperature controlled fluorescence on Au@Ag@PNIPAM-PTEBS microgels: effect of the metal core size on the MEF extension.

In this work, we present a novel method to produce thermoresponsive, monodisperse microgels which display temperature-dependent photoluminescence. The system is based on bimetallic cores of Au@Ag encapsulated within thermoresponsive poly(N-isopropylacrylamide) microgels and coated with a photoluminescent polymer (poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (PTEBS) using the Layer-by-Layer technique. The electromagnetic radiation used to excite the PTEBS induces a local electromagnetic field on the surface of the bimetallic cores that enhances the excitation and emission rates of the PTEBS, yielding a metal enhanced fluorescence (MEF). This effect was studied as a function of the bimetallic core size and the separation distance between the PTEBS and the bimetallic cores. Our results permit evaluation of the effect that the metallic core size of colloidal particles exerts on the MEF for the first time, and prove the relevance of the metallic cores to extend the effect far away from the metallic surface.

The C-terminal sterile alpha motif (SAM) domain of human p73 is a highly dynamic protein, which acquires high thermal stability through a decrease in backbone flexibility.

The α-splice variant of p73 (p73α), a homologue of the tumour suppressor p53, has close to its C terminus a sterile alpha motif (SAM), SAMp73, that is involved in protein-biomolecule interactions. The conformational stability of SAMp73 is low (∼5 kcal mol(-1)), although its thermal stability is high. To explain this high thermostability, we studied the dynamics of SAMp73 over a wide range of GdmCl (guanidine hydrochloride) concentrations and temperatures by NMR relaxation, NMR hydrogen-exchange (HX) and fluorescence lifetime approaches. The slowest exchanging residues of SAMp73 belong to the helical regions, and they did exchange by a global unfolding process. Moreover, SAMp73 was very flexible, with most of its amide protons affected by slow µs-ms conformational exchange. Within this time scale, the residues of SAMp73 with the largest exchange rates (R(ex)) were involved in binding with other molecules; therefore, the flexibility in the µs-ms range was associated with biological functions. As the [GdmCl] increased, the pico-to-nanosecond flexibility of the backbone amide protons raised, but it did so differently depending on the residue. We were able to obtain, for the first time, the linear [GdmCl]-variation of the local conformational entropies, m(S(i)), which ranged from 5.3 to 0.3 cal mol(-1) K(-1) M(-1), similar to those measured by using macroscopic techniques in other proteins. Conversely, the temperature dependence of the pico-to-nanosecond dynamics of the backbone amide protons of SAMp73 indicates that the flexibility of some residues decreased with the temperature; these results explain the high thermostability of the protein.

Nucleotide-induced conformational transitions in the CBS domain protein MJ0729 of Methanocaldococcus jannaschii.

Nucleotide-binding cystathionine ß-synthase (CBS) domains function as regulatory motifs in several proteins distributed through all kingdoms of life. This function has been proposed based on their affinity for adenosyl-derivatives, although the exact binding mechanisms remain largely unknown. The question of how CBS domains exactly work is relevant because in humans, several genetic diseases have been associated with mutations in those motifs. In this work, we describe the adenosyl-ligand (AMP, ATP, NADP and SAM) properties of the wild-type CBS domain protein MJ0729 from Methanocaldococcus jannaschii by using a combination of spectroscopic techniques (fluorescence, FTIR and FRET). The fluorescence results show that binding to AMP and ATP occurs with an apparent dissociation constant of ~10 µM, and interestingly enough, binding induces protein conformational changes, as shown by FTIR. On the other hand, fluorescence spectra (FRET and steady-state) did not change upon addition of NADP and SAM to MJ0729, suggesting that tryptophan and/or tyrosine residues were not involved in the recognition of those ligands; however, there were changes in the secondary structure of the protein upon addition of NADP and SAM, as shown by FTIR (thus, indicating binding to the nucleotide). Taken together, these results suggest that: (i) the adenosyl ligands bind to MJ0729 in different ways, and (ii) there are changes in the protein secondary structure upon binding of the nucleotides.

Aggregation of antitumoral drug emodin on Ag nanoparticles: SEF, SERS and fluorescence lifetime experiments.

We have studied the fluorescence and Raman emission of the anthraquinone drug emodin immobilized molecules on nanostructured silver surfaces, prepared through two different methods. Two different pHs (pH = 10 and pH = 6) have been used. The dye aggregation favors SEF at pH = 6, whereas quenching of fluorescence is observed at pH = 10, due to the short distance between emodin and Ag particles. Along with these results, SERS spectra have given us information about the different species present in the solution. We have used two different reducing agents to obtain the Ag nanoparticles: hydroxylamine hydrochloride and sodium citrate. In all the cases analysed, the enhancement of both SEF and SERS spectra, is larger for hydroxylamine hydrochloride than that for sodium citrate. We have also measured fluorescence lifetime, observing a shorter lifetime for emodin molecules near Ag nanoparticles than that for emodin solved in pure water, thus corroborating the results obtained in fluorescence emission spectra.

Interactions of 2,2,2-trifluoroethanol with aqueous micelles of Triton X-100.

The effect of 2,2,2-trifluoroethanol (TFE) on micellar properties of Triton X-100 (TX-100) in aqueous solutions was investigated by cloud point (CP), viscosity, surface tension, and fluorescence techniques. The critical micelle concentration (CMC) values of the corresponding mixtures were obtained by the pyrene 1:3 ratio method and by surface tension data using the pendant drop technique. All the techniques provided about the same values for the CMC. Up to 0.83 M TFE increased the CMC by 30%. The small increase in the CMC is consistent with a slight increase in the solubility of the TX-100. Fluorescence measurements indicate that the TFE decreased the aggregation number by about 30%. The CP decrease and the intrinsic viscosity increase with TFE concentration are consistent with a preferential interaction of TFE with TX-100 micelles. TFE molecules form hydrophobic domains in the micellar layer palisade because they hydrogen bond with the oxyethylene group in TX-100. The intrinsic viscosity data are consistent with an increase in micelle hydrodynamic radius owing to the presence of TFE.

Influence of the surfactant chain length on the fluorescence properties of a water-soluble conjugated polymer.

In this work, we report the influence of surfactant chain length and surfactant concentration on the photoluminescence (PL) of water-soluble pi-conjugated poly(thienyl ethylene oxide butyl sulfonate) (PTE-BS). We have used alkylammomium surfactants with 8, 9, 10, and 12 carbon atoms per hydrocarbon chain. The surfactant concentration was varied from 0.125 the critical micelle concentration (CMC) up to 2 times the CMC. The results show that at premicellar concentrations all the surfactants promote the polymer aggregation inducing an increase in the interchain charge transfer by pi-pi interactions, which competes with PL emission processes. However, in the premicellar range, the polymer PL emission is sharply affected by the surfactant chain length. Thus, the PL is quenched by the surfactants with the shortest tails, whereas the surfactants with the longest ones provoke an enhancement of the PL emission. This behavior has been associated with the capacity of the surfactants with the longest hydrocarbon chains to accommodate their tails inside the polymer, obstructing the appearance of pi-pi interchain interactions during aggregation and reducing intrachain defects. By contrast, at the CMC, the surfactant chain length does not modify the PL emission, since the excess of surfactant inhibits polymer aggregation, thus enhancing the efficiency of light emissive processes.

Identification of the antitumoral drug emodin binding sites in bovine serum albumin by spectroscopic methods.

Using SERS, fluorescence, circular dichroism and stopped-flow, we have unequivocally characterized the binding sites of emodin in bovine serum albumin. Emodin interacts with protein through two different binding sites corresponding to Sudlow's sites 1 and 2. Site 2, where the binding drug presents, in the cavity, a form between neutral and mono-anionic species slightly displaced to the neutral one, is the primary interaction site, with higher association binding constant, and hence, higher affinity than the other binding site. This interaction changes considerably the alpha-helical content of the protein and it occurs mainly within the interval [emodin]/[protein] < or = 2.0. The process involves a fast reaction and the observed rate constant increases when increasing the [emodin]/[protein] ratio. The secondary emodin interaction site corresponds to the Sudlow's site 1, where the drug shows a similar form to that deduced for site 2, but in this case, it is more displaced to mono-anionic species. This interaction does not change the alpha-helical content of bovine serum albumin, and it occurs mainly for [emodin]/[protein] > 2.0 ratios, the process implies a slower reaction than the union process to the site 2, with an observed rate constant that is invariable within the studied interval.

Characterization of binary solvent mixtures: the water-acetonitrile mixture.

Binary mixtures of water and acetonitrile (W/AN) were characterized in the light of the pure solvent scales, using suitable probe/homomorph couples. Various thermodynamic (vapour pressure, softness parameter, excess molar Gibbs energy and enthalpy of mixing) properties, surface tension, viscosity, and spectroscopic (IR, Raman and NMR) properties of the mixtures, and the distribution of molecular structures (viz. free CH3CN and CH3CN-H2O complexes) are described in terms of their polarity, acidity and basicity, and the descriptions examined in relation to a potential physical significance.