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Introduction: Cardiovascular surgery risk prediction models are widely applied in medical practice. However, they have been criticized for their low methodological quality and scarce external validation. An additional limitation added in Latin America is that most of these models have been developed in the United States or Europe, which present marked geographical differences. The objective of this study is to characterize the postoperative clinical events of cardiovascular surgeries with the use of cardiopulmonary bypass pump in a local setting and to evaluate the prediction of postoperative mortality using the EuroSCORE II predictive model. Methods: Cross-sectional study in an urban university hospital in Buenos Aires. Patients ≥21 years of age were included, with a clinical indication for on-pump cardiovascular surgery. Patients with incomplete clinical data regarding EuroSCORE II variables or in-hospital survival, ≥95 years of age, or undergoing heart transplantation were excluded. Results: 195 patients were enrolled. Postoperative mortality estimated by EuroSCORE II presented a clear underestimation of risk (3.0% vs 7.7%). Discrimination (AUC = 0.82; 95% CI 0.74-0.92) and goodness of fit of the model were adequate (χ2 = 7.91; p = 0.4418). The most frequent postoperative complications were postoperative heart failure (35.9%), vasoplegic shock (13.3%), and cardiogenic shock (10.26%). Conclusion: The EuroSCORE II is an appropriate tool to discriminate between different risk categories in patients undergoing on-pump cardiovascular surgery, although it underestimates the risk.

Introducción: Los modelos de predicción de riesgo de cirugías cardiovasculares se aplican ampliamente a la práctica médica. Sin embargo, han sido criticados por su baja calidad metodológica y escasa validación externa. En América Latina se agrega la limitación de que la mayoría de estos modelos fueron desarrollados en Estados Unidos o Europa, existiendo diferencias geográficas marcadas. Objetivo: El objetivo de este estudio es caracterizar los eventos clínicos postoperatorios de cirugías cardiovasculares con uso de bomba de circulación extracorpórea en un escenario local y evaluar la predicción de mortalidad postoperatoria del modelo predictivo EuroSCORE II. Métodos: Corte transversal en un hospital universitario urbano de Buenos Aires. Se incluyeron a pacientes ≥21 años de edad, con indicación de cirugía cardiovascular con uso de bomba. Se excluyeron a pacientes con datos clínicos incompletos respecto a las variables del EuroSCORE II o respecto a la sobrevida intrahospitalaria, con ≥95 años de edad o sometidos a trasplante cardíaco. Resultados: Se enrolaron 195 pacientes. La mortalidad postoperatoria estimada por el EuroSCORE II presentó una clara subestimación del riesgo (3,0% vs 7,7%). La discriminación (AUC = 0,82; IC95% 0,74-0,92) y la bondad del ajuste del modelo fueron adecuadas (χ2 = 7,91; p = 0,4418). Las complicaciones postoperatorias más frecuentes fueron insuficiencia cardíaca postoperatoria (35,9%), shock vasopléjico (13,3%) y shock cardiogénico (10,26%). Conclusión: El EuroSCORE II es una herramienta apropiada para discriminar entre diferentes categorías de riesgo en pacientes sometidos a cirugías cardiovasculares con uso de bomba, si bien subestima el riesgo.

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OBJECTIVES: Cardiopulmonary bypass (CPB) use is an essential strategy for many cardiovascular surgeries. However, its use and duration have been associated with a higher rate of postoperative complications, such as low cardiac output syndrome due to myocardial oedema and dysfunction. Though Aquaporin water channels have been implicated in myocardial water balance, their specific role in this clinical scenario has not been established. METHODS: In a consecutive study of 17 patients with severe aortic stenosis undergoing aortic valve replacement surgery, 2 myocardial biopsies of the left ventricle were taken: 1 before and 1 after CPB use. Sociodemographic, clinical and laboratory data were collected. Western blot and immunohistochemistry studies were performed. RESULTS: After CPB use, there was a mean increase of ∼62% in Aquaporin 1 protein levels (P = 0.001) and a mean reduction of ∼38% in Aquaporin 4 protein levels (P = 0.030). In immunohistochemistry assays, Aquaporin 1 was found lining small blood vessels, while Aquaporin 4 formed a circular label in cardiomyocytes. There were no changes in the localization of either protein following CPB use. During the observed on-pump time interval, there was a 1.7%/min mean increase in Aquaporin 1 (P = 0.021) and a 2.5%/min mean decrease in Aquaporin 4 (P = 0.018). Myocardial interstitial oedema increased by 42% (95% confidence interval 31-54%) after CPB use. Patients who developed low cardiac output syndrome were in the upper half of the median percentage change of Aquaporin expression. CONCLUSION: Time-dependent changes in cardiac Aquaporin expression may be associated with myocardial oedema and dysfunction related to CPB use.

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Sterol carrier protein 2 (SCP2) binds lipids with high affinity and broad specificity. The overall hydrophobicity, fluidity, and dipolar dynamics of the binding site of SCP2 from Yarrowia lipolytica were characterized using the environmentally-sensitive fluorescent probe Laurdan. The study revealed a binding site with an overall polarity similar to that of dichloromethane and an internal phase comparable to that of phospholipid membranes with coexisting solid-ordered and liquid-crystalline states. The fluorescence properties of bound Laurdan also revealed that the binding site of SCP2 can accommodate competitively more than one ligand, with micro and nanomolar dissociation constants. The much higher affinity for the second than for the first ligand implies that the most prominent SCP2 species in the cellular context are those occupied by two ligands. Thus SCP2 may carry a highly populated lipid in the background and a second one, specific for the functional purpose of SCP2. Our findings are important for the characterization of SCP2 biological functions and the design of specific inhibitors.

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Sterol Carrier Protein 2 (SCP2) has been associated with lipid binding and transfer activities. However, genomic, proteomic, and structural studies revealed that it is an ubiquitous domain of complex proteins with a variety functions in all forms of life. High-resolution structures of representative SCP2 domains are available, encouraging a comprehensive review of the structural basis for its success. Most SCP2 domains pertain to three major families and are frequently found as stand-alone or at the C-termini of lipid related peroxisomal enzymes, acetyltransferases causing bacterial resistance, and bacterial environmentally important sulfatases. We (1) analyzed the structural basis of the fold and the classification of SCP2 domains; (2) identified structure-determined sequence features; (3) compared the lipid binding cavity of SCP2 and other lipid binding proteins; (4) surveyed proposed mechanisms of SCP2 mediated lipid transfer between membranes; and (5) uncovered a possible new function of the SCP2 domain as a protein-protein recognition device.

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La hipertensión pulmonar tromboembólica crónica presenta un tratamiento curativo, siendo la endarterectomía pulmonar (EP) la opción terapéutica establecida. Sin embargo, la angioplastia con balón a arterias pulmonares puede ser considerada una alternativa viable en pacientes inoperables o en aquellos que persisten con hipertensión pulmonar tras una EP. Se reporta a continuación el primer caso de angioplastia con balón a arterias pulmonares realizada en un centro de Argentina.

Chronic thromboembolic pulmonary hypertension presents a curative treatment, with pulmonary endarterectomy being the established therapeutic option. However, balloon angioplasty to pulmonary arteries may be considered an alternative therapeutic option for patients with inoperable or residual disease after surgery. Herewith, we report the first case of chronic thromboembolic pulmonary hypertension treated with balloon pulmonary angioplasty in Argentina.

A hipertensão pulmonar tromboembólica crônica tem um tratamento curativo, a endarterectomia pulmonar (EP), a opção terapêutica estabelecida. No entanto, angioplastia com balão de artérias pulmonares pode ser considerado uma alternativa viável em pacientes inoperáveis ou aqueles que persistem com a hipertensão pulmonar após EP. Relatamos o primeiro caso de angioplastia pulmonar com balão no centro da Argentina.

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Sterol carrier protein 2 (SCP2), a small intracellular domain present in all forms of life, binds with high affinity a broad spectrum of lipids. Due to its involvement in the metabolism of long-chain fatty acids and cholesterol uptake, it has been the focus of intense research in mammals and insects; much less characterized are SCP2 from other eukaryotic cells and microorganisms. We report here the X-ray structure of Yarrowia lipolytica SCP2 (YLSCP2) at 2.2 Å resolution in complex with palmitic acid. This is the first fungal SCP2 structure solved, and it consists of the canonical five-stranded ß-sheet covered on the internal face by a layer of five α-helices. The overall fold is conserved among the SCP2 family, however, YLSCP2 is most similar to the SCP2 domain of human MFE-2, a bifunctional enzyme acting on peroxisomal ß-oxidation. We have identified the common structural elements defining the shape and volume of the large binding cavity in all species characterized. Moreover, we found that the cavity of the SCP2 domains is distinctly formed by carbon atoms, containing neither organized water nor rigid polar interactions with the ligand. These features are in contrast with those of fatty acid binding proteins, whose internal cavities are more polar and contain bound water. The results will help to design experiments to unveil the SCP2 function in very different cellular contexts and metabolic conditions.

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Pseudomonas aeruginosa infections constitute a widespread health problem with high economical and social impact, and the phosphorylcholine phosphatase (PchP) of this bacterium is a potential target for antimicrobial treatment. However, drug design requires high-resolution structural information and detailed biophysical knowledge not available for PchP. An obstacle in the study of PchP is that current methods for its expression and purification are suboptimal and allowed only a preliminary kinetic characterization of the enzyme. Herein, we describe a new procedure for the efficient preparation of recombinant PchP overexpressed in Escherichia coli. The enzyme is purified from urea solubilized inclusion bodies and refolded by dialysis. The product of PchP refolding is a mixture of native PchP and a kinetically-trapped, alternatively-folded aggregate that is very slowly converted into the native state. The properly folded and fully active enzyme is isolated from the refolding mixture by size-exclusion chromatography. PchP prepared by the new procedure was subjected to chemical and biophysical characterization, and its basic optical, hydrodynamic, metal-binding, and catalytic properties are reported. The unfolding of the enzyme was also investigated, and its thermal stability was determined. The obtained information should help to compare PchP with other phosphatases and to obtain a better understanding of its catalytic mechanism. In addition, preliminary trials showed that PchP prepared by the new protocol is suitable for crystallization, opening the way for high-resolution studies of the enzyme structure.

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Sterol carrier protein 2 (SCP2) is an intracellular protein domain found in all forms of life. It was originally identified as a sterol transfer protein, but was recently shown to also bind phospholipids, fatty acids, and fatty-acyl-CoA with high affinity. Based on studies carried out in higher eukaryotes, it is believed that SCP2 targets its ligands to compartmentalized intracellular pools and participates in lipid traffic, signaling, and metabolism. However, the biological functions of SCP2 are incompletely characterized and may be different in microorganisms. Herein, we demonstrate the preferential localization of SCP2 of Yarrowia lipolytica (YLSCP2) in peroxisome-enriched fractions and examine the rate and mechanism of transfer of anthroyloxy fatty acid from YLSCP2 to a variety of phospholipid membranes using a fluorescence resonance energy transfer assay. The results show that fatty acids are transferred by a collision-mediated mechanism, and that negative charges on the membrane surface are important for establishing a "collisional complex". Phospholipids, which are major constituents of peroxisome and mitochondria, induce special effects on the rates of transfer. In conclusion, YLSCP2 may function as a fatty acid transporter with some degree of specificity, and probably diverts fatty acids to the peroxisomal metabolism.

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We report a biophysical characterisation of apo-sterol carrier protein-2 from Yarrowia lipolytica (YLSCP-2) and its urea-induced unfolding followed by intrinsic tryptophan fluorescence, far-UV CD, ANS binding, and small angle X-ray scattering (SAXS). The unfolding is described as a three-step process. The first steps, between 1 and 2 M urea, have well-defined cooperative character and are related to the break down of most of the tertiary and secondary structure. The third step, at higher urea concentrations, is characterised by the disruption of residual interactions involving the single tryptophan. A 3D structure model for the YLSCP2 monomer was built by homology, which account for the fluorescence and CD spectroscopy data and is consistent with the binding mode observed for other SCP2. SAXS and cross-linking experiments suggest that YLSCP2 dimerise at approximately 70 microM concentration.

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The 14-kDa sterol carrier protein 2 (SCP2) domain is present in Eukaria, Bacteria and Archaea, and has been implicated in the transport and metabolism of lipids. We report the cloning, expression, purification and physicochemical characterization of a SCP2 from the yeast Yarrowia lipolytica (YLSCP2). Analytical size-exclusion chromatography, circular dichroism and fluorescence spectra, indicate that recombinant YLSCP2 is a well-folded monomer. Thermal unfolding experiments show that SCP2 maximal stability is at pH 7.0-9.0. YLSCP2 binds cis-parinaric acid and palmitoyl-CoA with KD values of 81+/-40 nM and 73+/-33 nM, respectively, sustaining for the first time the binding of fatty acids and their CoA esters to a nonanimal SCP2. The role of yeast SCP2 and other lipid binding proteins in transport, storage and peroxisomal oxidation of fatty acids is discussed.

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The three-dimensional structure of protein is encoded in the sequence, but many amino acid residues carry no essential conformational information, and the identity of those that are structure-determining is elusive. By circular permutation and terminal deletion, we produced and purified 25 Bacillus licheniformis beta-lactamase (ESBL) variants that lack 5-21 contiguous residues each, and collectively have 82% of the sequence and 92% of the non-local atom-atom contacts eliminated. Circular dichroism and size-exclusion chromatography showed that most of the variants form conformationally heterogeneous mixtures, but by measuring catalytic constants, we found that all populate, to a greater or lesser extent, conformations with the essential features of the native fold. This suggests that no segment of the ESBL sequence is essential to the structure as a whole, which is congruent with the notion that local information and modular organization can impart most of the tertiary fold specificity and cooperativity.

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The effects of C-terminal truncation on the equilibrium folding transitions and folding kinetics of B. licheniformis exo small beta-lactamase (ES-betaL) have been measured. ES-betaL lacking 19 residues (ES-betaL(C)(Delta)(19)) has no enzymic activity. Deletion of the last 14 residues produces ES-betaL(C)(Delta)(14), which is 0.1% active. The enzyme lacking nine residues (ES-betaL(C)(Delta)(9)) is nearly fully active, has native optical and hydrodynamic properties, and is protease resistant, a distinguishing feature of the wild-type enzyme. Although ES-betaL(C)(Delta)(9) folds properly, it does so 4 orders of magnitude slower than ES-betaL, making possible the isolation and characterization of a compact intermediate state (I(P) ES-betaL(C)(Delta)(9)). Based on the analysis of folding rates and equilibrium constants, we propose that equilibrium between I(P) ES-betaL(C)(Delta)(9) and other intermediate slow folding. Residues removed in ES-betaL(C)(Delta)(9) and ES-betaL(C)(Delta)(14) are helical and firmly integrated into the enzyme body through many van der Waals interactions involving residues distant in sequence. The results suggest that the deleted residues play a key role in the folding process and also the existence of a modular organization of the protein matrix, at the subdomain level. The results are compared with other examples of this kind in the folding literature.

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Una encuesta anonima voluntaria y privada se aplico a 247 mujeres internadas por aborto incompleto inducido, en el servicio de Ginecologia del Hospital Obrero de La Paz, que registra un incremento paulatino del problema. Los resultados revelan que esas mujeres tienen todavia muchos años de vida reproductiva y que han recurrido al aborto fundamentalmente por razones economicas (61%), pues el 75% de ellas cumplia alguna actividad laboral, aunque el ingreso mensual familiar era menos a Bs 200 en 74,5% de los casos. El 78% sabia como evitar el embarazo pero no lo hizo; como tal recurrio al aborto, que estuvo a cargo de un medico en el 68% del todal de casos. Por todo lo anterior, podemos afirmar que muchas mujeres han convertido el aborto en un peligroso metodo de planificacion familiar. Ademas la informacion recogida revela que hay falta de informacion y de servicios de anticoncepticon. Consideramos pues que la solucion del aborto inducido no es legal sino medica a traves de la planificacion familiar.

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