Carbapenemase-Producing Extraintestinal Pathogenic Escherichia coli From Argentina: Clonal Diversity and Predominance of Hyperepidemic Clones CC10 and CC131.

Extraintestinal pathogenic Escherichia coli (ExPEC) causes infections outside the intestine. Particular ExPEC clones, such as clonal complex (CC)/sequence type (ST)131, have been known to sequentially accumulate antimicrobial resistance that starts with chromosomal mutations against fluoroquinolones, followed with the acquisition of bla CTX-M-15 and, more recently, carbapenemases. Here we aimed to investigate the distribution of global epidemic clones of carbapenemase-producing ExPEC from Argentina in representative clinical isolates recovered between July 2008 and March 2017. Carbapenemase-producing ExPEC (n = 160) were referred to the Argentinean reference laboratory. Of these, 71 were selected for genome sequencing. Phenotypic and microbiological studies confirmed the presence of carbapenemases confirmed as KPC-2 (n = 52), NDM-1 (n = 16), IMP-8 (n = 2), and VIM-1 (n = 1) producers. The isolates had been recovered mainly from urine, blood, and abdominal fluids among others, and some were from screening samples. After analyzing the virulence gene content, 76% of the isolates were considered ExPEC, although non-ExPEC isolates were also obtained from extraintestinal sites. Pan-genome phylogeny and clonal analysis showed great clonal diversity, although the first phylogroup in abundance was phylogroup A, harboring CC10 isolates, followed by phylogroup B2 with CC/ST131, mostly H30Rx, the subclone co-producing CTX-M-15. Phylogroups D, B1, C, F, and E were also detected with fewer strains. CC10 and CC/ST131 were found throughout the country. In addition, CC10 nucleated most metalloenzymes, such as NDM-1. Other relevant international clones were identified, such as CC/ST38, CC155, CC14/ST1193, and CC23. Two isolates co-produced KPC-2 and OXA-163 or OXA-439, a point mutation variant of OXA-163, and three isolates co-produced MCR-1 among other resistance genes. To conclude, in this work, we described the molecular epidemiology of carbapenemase-producing ExPEC in Argentina. Further studies are necessary to determine the plasmid families disseminating carbapenemases in ExPEC in this region.

Are Oxidative Stress Biomarkers Sensitive to Environmental Concentrations of Chlorpyrifos Exposed to the Freshwater Crab, Zilchiopsis collastinensis (Decapoda; Trichodactylidae)?

Global trends in pesticide use can increase aquatic pollution and affect resident fisheries. Crabs exposed to organophosphate pesticides, such as chlorpyrifos, may increase production of reactive oxygen species (ROS), affecting the pro-oxidant/antioxidant balance. Zichiopsis collastinensis crabs were exposed to environmentally relevant concentrations of chlorpyrifos (0.1 and 0.5 µg L-1). Effects on the oxidative stress enzymes catalase, superoxide dismutase, glutathione S-transferases, glutathione reductase, and on thiobarbituric acid reactive substances and hydrogen peroxide concentrations were evaluated at four intervals during 96 h exposures. Exposures caused decreased GST activity and increased H2O2 levels in gills. There were modifications of GST, CAT and SOD activities in the hepatopancreas after 12 h of exposure, and an increase of H2O2 levels at every exposure interval observed. The present study proved that chlorpyrifos lead to oxidative stress in Z. collastinensis. However other enzymatic/non-enzymatic responses should be further investigated in order to be included as part of a battery of biomarkers, together with H2O2 levels, which is a parameter highly recommended to be taken into account.

Genetics of alternative splicing evolution during sunflower domestication.

Alternative splicing enables organisms to produce the diversity of proteins necessary for multicellular life by using relatively few protein-coding genes. Although differences in splicing have been identified among divergent taxa, the shorter-term evolution of splicing is understudied. The origins of novel splice forms, and the contributions of alternative splicing to major evolutionary transitions, are largely unknown. This study used transcriptomes of wild and domesticated sunflowers to examine splice differentiation and regulation during domestication. We identified substantial splicing divergence between wild and domesticated sunflowers, mainly in the form of intron retention. Transcripts with divergent splicing were enriched for seed-development functions, suggesting that artificial selection impacted splicing patterns. Mapping of quantitative trait loci (QTLs) associated with 144 differential splicing cases revealed primarily trans-acting variation affecting splicing patterns. A large proportion of identified QTLs contain known spliceosome proteins and are associated with splicing variation in multiple genes. Examining a broader set of wild and domesticated sunflower genotypes revealed that most differential splicing patterns in domesticated sunflowers likely arose from standing variation in wild Helianthus annuus and gained frequency during the domestication process. However, several domesticate-associated splicing patterns appear to be introgressed from other Helianthus species. These results suggest that sunflower domestication involved selection on pleiotropic regulatory alleles. More generally, our findings indicate that substantial differences in isoform abundances arose rapidly during a recent evolutionary transition and appear to contribute to adaptation and population divergence.

[Chronic pulmonary insufficiency after tetralogy of Fallot and pulmonary stenosis intervention. Pulmonary valve replacement with mechanical prosthesis]. / Insuficiencia pulmonar crónica secundaria a tetralogía de Fallot y estenosis pulmonar intervenida. Recambio valvular pulmonar con prótesis metálica.

INTRODUCTION: Tetralogy of Fallot and pulmonary stenosis are a frequent cause of consultation in patients with congenital heart disease. Interventions performed in infancy can cause residual pulmonary insufficiency and may require pulmonary valve replacement when adults. METHODS: From 2003 to 2007, 37 patients underwent right ventricular outflow tract or pulmonary valve intervention (tetralogy of Fallot and pulmonary stenosis). Differences between echocardiographic parameters in both pathologies, indications for pulmonary valvular replacement and the type of prosthesis used, were studied. RESULTS: 25 (67.6 %) patients had tetralogy of Fallot and 12 (32.4 %) pulmonary stenosis. In the pulmonary stenosis group, 7 patients had pulmonary valvulotomy in infancy and 5 had percutaneous pulmonary valvuloplasty in adulthood. Fallot patients received a transannular patch. No significant differences were seen in echocardiographic parameters (right and left ventricular diameter, pulmonary insufficiency, transpulmonary gradient and left ventricular ejection fraction). Mechanical prosthesis valve replacement was performed in 5 (13.5 %) patients, with no morbidity-mortality and with a significant improvement of the functional class. CONCLUSIONS: Chronic pulmonary insufficiency is a frequent complication after intervention of tetralogy of Fallot and pulmonary stenosis. Mechanical prosthesis valve replacement has low morbidity-mortality and low risk of complications after short to medium-term follow-up.

Insuficiencia pulmonar crónica secundaria a tetralogía de Fallot y estenosis pulmonar intervenida. Recambio valvular pulmonar con prótesis metálica / Chronic pulmonary insufficiency after tetralogy of Fallot and pulmonary stenosis intervention. Pulmonary valve replacement with mechanical prosthesis

Introducción. La tetralogía de Fallot y la estenosis pulmonar intervenida son causas frecuentes de consulta en pacientes con cardiopatías congénitas. Las intervenciones realizadas en la infancia conllevan una insuficiencia pulmonar residual que puede requerir recambio valvular pulmonar en la edad adulta. Métodos. Entre 2003 y 2007 se controló a 37 pacientes con intervencionismo sobre el tracto de salida del ventrículo derecho y la válvula pulmonar (tetralogía de Fallot y estenosis pulmonar). Se realizó un estudio para evaluar la diferencia entre los parámetros ecocardiográficos de ambas patologías, las indicaciones de recambio valvular pulmonar y el tipo de prótesis implantada. Resultados. Del total de pacientes con intervención sobre la válvula pulmonar, 25 (67,6 %) tenían tetralogía de Fallot y 12 (32,4 %), estenosis pulmonar. De los pacientes con estenosis pulmonar, a 7 se les realizó valvulotomía en la infancia y a 5, valvuloplastia pulmonar en la edad adulta. A los pacientes con tetralogía de Fallot se les realizó una ampliación transanular con parche. La diferencia de medias de los parámetros ecocardiográficos estudiados (diámetros de los ventrículos derecho e izquierdo, grado de insuficiencia pulmonar, gradiente transpulmonar y fracción de eyección del ventrículo izquierdo) no fue significativa. Se realizó recambio valvular pulmonar con prótesis metálica en 5 (13,5 %) pacientes, sin morbimortalidad y con una mejoría significativa del grado funcional. Conclusiones. La insuficiencia pulmonar crónica es una complicación frecuente en los pacientes con tetralogía de Fallot y estenosis pulmonar intervenidas. El recambio pulmonar con prótesis metálica es un procedimiento de baja morbimortalidad y escaso riesgo de complicaciones a corto-medio plazo

Introduction. Tetralogy of Fallot and pulmonary stenosis are a frequent cause of consultation in patients with congenital heart disease. Interventions performed in infancy can cause residual pulmonary insufficiency and may require pulmonary valve replacement when adults. Methods. From 2003 to 2007, 37 patients underwent right ventricular outflow tract or pulmonary valve intervention (tetralogy of Fallot and pulmonary stenosis). Differences between echocardiographic parameters in both pathologies, indications for pulmonary valvular replacement and the type of prosthesis used, were studied. Results. 25 (67.6 %) patients had tetralogy of Fallot and 12 (32.4 %) pulmonary stenosis. In the pulmonary stenosis group, 7 patients had pulmonary valvulotomy in infancy and 5 had percutaneous pulmonary valvuloplasty in adulthood. Fallot patients received a transannular patch. No significant differences were seen in echocardiographic parameters (right and left ventricular diameter, pulmonary insufficiency, transpulmonary gradient and left ventricular ejection fraction). Mechanical prosthesis valve replacement was performed in 5 (13.5 %) patients, with no morbidity-mortality and with a significant improvement of the functional class. Conclusions. Chronic pulmonary insufficiency is a frequent complication after intervention of tetralogy of Fallot and pulmonary stenosis. Mechanical prosthesis valve replacement has low morbidity-mortality and low risk of complications after short to medium-term follow-up

[Clinical assessment of a new anesthetic system: the Temel Supra (II)]. / Análisis clínico de un nuevo sistema de anestesia: Temel Supra (II).

OBJECTIVES: To assess the clinical performance of a new anesthetic system developed to provide novel advantages in ventilating the anesthetized patient. PATIENTS AND METHOD: The clinical performance of the Temel Supra was evaluated in 100 adult patients who were anesthetized and ventilated using the device. RESULTS: The patients were adequately oxygenated and ventilated; no adverse events were observed. An open circuit, low flow, or closed circuit could be chosen freely. Ventilation was fully monitored: among the variables measured were rebreathed volume; leaks while the patient was connected; consumption of oxygen, nitrous oxide and anesthetic agents; and cardiac output (noninvasively). CONCLUSIONS: Ventilation and gas exchange were satisfactory in all cases even though some patients developed considerable respiratory impedance. The monitoring of oxygen and other gases consumed and of carbon dioxide produced provided very valuable information about metabolism and pharmacokinetics. The noninvasive monitoring of cardiac output seems to us to be a useful feature for aiding hemodynamic control. The independence of the open and closed circuits means that expired gases do not pass through the canister when the open circuit is used, resulting in savings on soda lime for drying. During pressure-control ventilation, the system maintains a plateau to guarantee better distribution of inspired gases. Other important features are warnings, constant monitoring of leaks, the 100% efficacy of the circuit, and the low internal volume.

[Bilateral compartment syndrome after surgical perfusion for chronic ischemia of the lower extremities]. / Síndrome compartimental bilateral tras reperfusión quirúrgica en la isquemia crónica de miembros inferiores.

A 61-year-old man diagnosed with advanced stage Leriche syndrome underwent revascularization surgery with placement of an aortobifemoral shunt and prosthesis under combined general and lumbar epidural anesthesia. After 6 hours he developed bilateral lower extremity compartment syndrome with acute anuric kidney failure caused by severe rhabdomyolysis. Thirty hours after surgery the patient suffered cardiac arrest due to hyperkalemia and was unresponsive to advanced cardiopulmonary resuscitation. The delay in diagnosis, in part owing to the epidural block provided for surgery, and loss of muscle mass led to the unfavorable outcome in this case.

Towards new thymidine phosphorylase/PD-ECGF inhibitors based on the transition state of the enzyme reaction.

Computational studies have been conducted to built a closed form of TPase and to characterize the transition state of the phosphorylisis reaction catalyzed by TPase. The results obtained point to a crucial role of His-85 and the O2 of thymine in the catalysis. This modelled transition state forms the basis for the design of new TPase inhibitors.

Molecular dynamics simulations of the conformational changes of the glutamate receptor ligand-binding core in the presence of glutamate and kainate.

Excitatory synaptic transmission is mediated by ionotropic glutamate receptors (iGluRs) through the induced transient opening of transmembrane ion channels. The three-dimensional structure of the extracellular ligand-binding core of iGluRs shares the overall features of bacterial periplasmic binding proteins (PBPs). In both families of proteins, the ligand-binding site is arranged in two domains separated by a cleft and connected by two peptide stretches. PBPs undergo a typical hinge motion of the two domains associated with ligand binding that leads to a conformational change from an open to a closed form. The common architecture suggests a similar closing mechanism in the ligand-binding core of iGluRs induced by the binding of specific agonists. Starting from the experimentally determined kainate-bound closed form of the S1S2 GluR2 construct, we have studied by means of molecular dynamics simulations the opening motion of the ligand-binding core in the presence and in the absence of both glutamate and kainate. Our results suggest that the opening/closing interdomain hinge motions are coupled to conformational changes in the insertion region of the transmembrane segments. These changes are triggered by the interaction of the agonists with the essential Glu 209 residue. A plausible mechanism for the coupling of agonist binding to channel gating is discussed.

Soft- and hard-modeling approaches for the determination of stability constants of metal-peptide systems by voltammetry.

The Zn(2+)-glutathione system is studied as a model for metal-peptide systems where some critical factors must be considered when using voltammetric techniques for the determination of stability constants. These factors are the presence of side reactions (in this case, both the protonation of glutathione and the hydrolysis of Zn(2+)), the association-dissociation rates of the complexes compared with the time scales of the measurements (which makes the complexes electrochemically labile or inert), and the electron transfer kinetics on the electrode surface (which makes the metal ion reduction reversible or irreversible). For the study of these factors, three data treatment approaches have been applied: (i) the electrochemical hard-modeling approach (modelization of both chemical equilibrium and electrochemical processes), (ii) a chemical hard-modeling approach (modelization of chemical equilibria only, based on the least-squares curve-fitting program SQUAD), and (iii) a previously developed model-free soft-modeling approach based on multivariate curve resolution with a constrained alternating least-squares optimization. By analyzing differential pulse polarographic data obtained under different experimental conditions, the influence of the mentioned factors on every approach is discussed and, if possible, the corresponding stability constants are computed. The results of this study showed the potential usefulness of voltammetry in combination with hard- and soft-modeling data analysis for the study of peptide complexation equilibria of metal ions such as Zn which have neither relevant spectroscopic properties nor proper isotopes for NMR measurements.

[A superior vena cava syndrome due to a surgical retractor]. / Síndrome de vena cava superior por retractor quirúrgico.

A 56-year-old male diagnosed of epidermoid carcinoma of the right lung (T4 N0 M0, stage IIIb) is described. He had earlier received chemotherapy and radiotherapy and was scheduled for removal of the right lung. During surgery the need to resect tumor infiltration of the right atrium became evident. During weaning from by-pass sudden deterioration of hemodynamics occurred with poor response to volume and inotropic drugs. Superior vena cava syndrome due to traction of the innominate trunk from a surgical retractor was diagnosed; the crisis resolved when the retractor was withdrawn. We discuss the pathophysiology of this clinical picture and relevant intraoperative aspects.

Two-phase induction of the nonnative alpha-helical form of beta-lactoglobulin in the presence of trifluoroethanol.

The trifluoroethanol-dependent induction of the nonnative alpha-helical form of beta-lactoglubulin has been studied by circular dichroism spectroscopy. Data analysis is performed by factor analysis and multivariate curve resolution. An intermediate form in the induction of the alpha-helical form of the beta-lactoglobulin has been identified at low TFE concentration. By application of an alternating least-squares algorithm, the CD spectrum corresponding to the intermediate form has been resolved. The deconvolution of this CD spectrum shows a secondary structure content more in agreement with the one predicted from the amino acid sequence than the secondary structure of the helical form obtained at higher TFE concentrations. The additional alpha-helical content of the form present at higher TFE concentrations could be due to nonspecific interaction of TFE with the polypeptide chain.

Multivariate curve resolution: a possible tool in the detection of intermediate structures in protein folding.

Different multivariate data analysis techniques based on factor analysis and multivariate curve resolution are shown for the study of biochemical evolutionary processes like conformational changes and protein folding. Several simulated CD spectral data sets describing different hypothetical protein folding pathways are analyzed and discussed in relation to the feasibility of factor analysis techniques to detect and resolve the number of components needed to explain the evolution of the CD spectra corresponding to the process (i.e., to detect the presence of intermediate forms). When more than two components (the native and unordered forms) are needed to explain the evolution of the spectra, an iterative multivariate curve resolution procedure based on an alternating least squares algorithm is proposed to estimate the CD spectrum corresponding to the intermediate form.

[Common variable immunodeficiency associated with autoimmune thrombocytopenia: anesthetic management]. / Inmunodeficiencia variable común asociada a trombopenia autoinmune: manejo anestésico.

A 44-year-old man diagnosed of common variable immunodeficiency associated with thrombopenia due to autoimmunity required anesthesia for anal fissure repair and hemorrhoidectomy. Hemostatic complications developed after surgery, with extreme thrombopenia (1,000 platelets/pl) and analytical changes that necessitated administration of six units of platelets from apheresis, as well as immunoglobulins, antifibrinolytic agents (e-aminocaproic acid) and granulocytic colony stimulating factors. Anesthesia for such patients is reviewed, with emphasis on careful management of the airways, preparation of sufficient material for surgery (rapid transfusion equipment, large caliber intravenous catheters, sterile material) and orientation of anesthetic technique toward general anesthesia through a laryngeal mask.

Application of multivariate curve resolution to voltammetric data. II. Study of metal-binding properties of the peptides.

The complexation of Cd2+ by glutathione (GSH), in 0.13 m borate buffer at pH 9.5, was studied by differential pulse polarography (DPP) and multivariate curve resolution. The Cd-GSH system has been chosen as a model to check the possibilities of this new polarographic approach to the study of metal ion complexation by peptides. Experimental data obtained by DPP for different Cd2+-to-GSH concentration ratios have been analyzed by a procedure which consists of using several chemometrical techniques based on factor analysis: principal component analysis, evolving factor analysis, and multivariate curve resolution with alternating least-squares (ALS) optimization. The use of different constraints during the ALS optimization process, such as nonnegativity and unimodality constraints, yields the optimal sought solution from a chemical point of view. In the present work, a new constraint has been implemented during ALS optimization to take into account the expected peak-shaped signal of DPP. This data treatment allows us to detect simultaneously the formation of 1:1 and 1:2 Cd:GSH complexes which were very difficult to detect by univariate analysis of DPP data. It is concluded that the described multivariate curve resolution method could be a reliable tool for studying metal-binding properties of peptides.

Transferrin binding capacity as a marker of differentiation and maturation of rat erythroid cells fractionated by counter current distribution in aqueous polymer two-phase systems.

Rat bone marrow cell populations, containing different proportions of erythroid cells, have been fractionated by counter-current distribution in the non-charge-sensitive dextran/polyethyleneglycol two-phase systems on the basis of hydrophobic cell surface properties. Cell fractions with a low distribution coefficient, which contain non-erythroid cells and early erythoblasts, showed a low transferrin binding capacity and a low haemoglobin/cell ratio whereas cell fractions with a high distribution coefficient, which contain intermediate-late erythroblasts and mature red cells, showed an elevated transferrin binding capacity and the highest haemoglobin/cell ratio. These results support transferrin binding capacity as a good marker parameter for the erythroid bone marrow cell differentiation and maturation processes.

Transferrin-binding capacity by rat bone marrow populations containing different proportions of erythroid cells.

The transferrin-binding capacity of rat bone marrow cells and different erythroid-enriched populations from rat bone marrow has been studied and compared with that previously reported for pure reticulocyte populations. Two components with different transferrin-binding capacities were found. The one with higher affinity was present mainly in erythroid cells and showed an association constant similar to that observed in reticulocyte populations. The component with a lower transferrin affinity was observed mainly in bone marrow fractions containing low proportions of erythroid cells.

Fractionation of erythroblasts with affinity-mediated modifications of their electrical properties using counter-current distribution.

We have previously reported the possibility of modifying the electrical properties of cells by means of their interaction with a specific ligand carrying a polyelectrolyte (Anal Biochem 200: 280-285). This selective modification of receptor-containing cells changed their partition in a charge-sensitive aqueous two-phase system. We here present the fractionation of electrically modified erythroblasts by the use of an automatic multiple-partition procedure, counter-current distribution. The cells were fractionated according to the degree of differentiation of erythroblasts as evaluated from the hemoglobin content as well as the relative activities of the two enzymes, 3-phosphoglycerate kinase and bisphospho-glycerate mutase.