2,734 research outputs found
Resonance energy transfer and superradiance mediated by plasmonic nanowaveguides
We show how both the subwavelength confinement associated with surface plasmons and the one-dimensional character of plasmonic waveguides can be exploited to enhance the coupling between quantum emitters. Resonance energy transfer and the phenomenon of superradiance are investigated in three different waveguiding schemes (wires, wedges, and channels) by means of the Finite Element Method. We also develop a simplified model that is able to capture the main features of the numerical results. © 2010 American Chemical Societ
Host-Specific Enzyme-Substrate Interactions in SPM-1 Metallo-beta-Lactamase are Modulated by Second Sphere Residues
Pseudomonas aeruginosa is one of the most virulent and resistant non-fermenting Gram-negative pathogens in the clinic. Unfortunately, P. aeruginosa has acquired genes encoding metallo-beta-lactamases (MBLs), enzymes able to hydrolyze most beta-lactam antibiotics. SPM-1 is an MBL produced only by P. aeruginosa, while other MBLs are found in different bacteria. Despite similar active sites, the resistance profile of MBLs towards beta-lactams changes from one enzyme to the other. SPM-1 is unique among pathogen-associated MBLs in that in that it contains "atypical" second sphere residues (S84, G121). Codon randomization on these positions and further selection of resistance-conferring mutants was performed. MICs, periplasmic enzymatic activity, Zn(II) requirements, and protein stability was assessed. Our results indicated that identity of second sphere residues modulates the substrate preferences and the resistance profile of SPM-1 expressed in P. aeruginosa. The second sphere residues found in wild type SPM-1 give rise to a substrate selectivity that is observed only in the periplasmic environment. These residues also allow SPM-1 to confer resistance in P. aeruginosa under Zn(II)-limiting conditions, such as those expected under infection. By optimizing the catalytic efficiency towards beta-lactam antibiotics, the enzyme stability and the Zn(II) binding features, molecular evolution meets the specific needs of a pathogenic bacterial host by means of substitutions outside the active site.Fil: Gonzalez, Lisandro Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Rosario. Instituto de BiologĂa Molecular y Celular de Rosario; ArgentinaFil: Moreno, Diego Martin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Rosario. Instituto de QuĂmica Rosario; ArgentinaFil: Bonomo, Robert A.. Case Western Reserve University; Estados UnidosFil: Vila, Alejandro Jose. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Rosario. Instituto de BiologĂa Molecular y Celular de Rosario; Argentin
Didactic strategy for the promotion of reading using technology with three-year-old boys and girls from the El Tintal Manuel Zapata Olivella Public Library.
El presente trabajo de grado identificĂł como problemĂĄtica el uso instrumentalizado de la tecnologĂa en niños y niñas de tres años durante las visitas que Ă©stos realizaron en la Biblioteca PĂșblica El Tintal Manuel Zapata Olivella. A partir de la caracterizaciĂłn de la necesidad se plantea como objetivo proponer una estrategia didĂĄctica para la promociĂłn de lectura desde el uso de la tecnologĂa para niños y niñas de 3 años de la Biblioteca PĂșblica El Tintal Manuel Zapata Olivella de la ciudad de BogotĂĄ D.C.The present degree work identified as problematic the instrumentalized use of technology in three-year-old boys and girls during their visits to the Manuel Zapata Olivella El Tintal Public Library. Based on the characterization of the need, the objective is to propose a didactic strategy for the promotion of reading from the use of technology for 3-year-old boys and girls of the El Tintal Manuel Zapata Olivella Public Library of the city of BogotĂĄ D.C
Coordination of peroxide to the CuM center of peptidylglycine α-hydroxylating monooxygenase (PHM): Structural and computational study
Many bioactive peptides, such as hormones and neuropeptides, require amidation at the C terminus for their full biological activity. Peptidylglycine a-hydroxylating monooxygenase (PHM) performs the first step of the amidation reaction-the hydroxylation of peptidylglycine substrates at the Ca position of the terminal glycine. The hydroxylation reaction is copper- and O2-dependent and requires 2 equiv of exogenous reductant. The proposed mechanism suggests thatO2 is reduced by two electrons, each provided by one of two nonequivalent copper sites in PHM (CuH and CuM). The characteristics of the reduced oxygen species in the PHM reaction and the identity of the reactive intermediate remain uncertain. To further investigate the nature of the key intermediates in the PHM cycle, we determined the structure of the oxidized form of PHM complexed with hydrogen peroxide. In this 1.98-A° -resolution structure (hydro)peroxide binds solely to CuM in a slightly asymmetric side-on mode. The O-O interatomic distance of the copperbound ligand is 1.5 A ° , characteristic of peroxide/hydroperoxide species, and the Cu-O distances are 2.0 and 2.1 A ° . Density functional theory calculations using the first coordination sphere of the CuM active site as a model system show that the computed energies of the side-on L3CuM(II)-O2 2- species and its isomeric, end-on structure L3CuM(I)-O2 - are similar, suggesting that both these intermediates are significantly populated within the protein environment. This observation has important mechanistic implications. The geometry of the observed side-on coordinated peroxide ligand in L3CuM(II)O2 2- is in good agreement with the results of a hybrid quantum mechanical-molecular mechanical optimization of this species.Fil: Rudzka, Katarzyna. University Johns Hopkins; Estados UnidosFil: Moreno, Diego Martin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Rosario. Instituto de QuĂmica Rosario; Argentina. Universidad de Buenos Aires; ArgentinaFil: Eipper, Betty. University Of Connecticut; Estados UnidosFil: Mains, Richard. University Of Connecticut; Estados UnidosFil: Estrin, Dario Ariel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de QuĂmica, FĂsica de los Materiales, Medioambiente y EnergĂa; Argentina. Universidad de Buenos Aires; ArgentinaFil: Amzel, L. Mario. University Johns Hopkins; Estados Unido
Shaping substrate selectivity in a broad-spectrum metallo-ÎČ-lactamase
Metallo-ÎČ-lactamases (MBLs) are the major group of carbapenemases produced by bacterial pathogens. The design of MBL inhibitors has been limited by, among other issues, incomplete knowledge about how these enzymes modulate substrate recognition. While most MBLs are broad-spectrum enzymes, B2 MBLs are exclusive carbapenemases. This narrower substrate profile has been attributed to a sequence insertion present in B2 enzymes that limits accessibility to the active site. In this work, we evaluate the role of sequence insertions naturally occurring in the B2 enzyme Sfh-I and in the broad-spectrum B1 enzyme SPM-1. We engineered a chimeric protein in which the sequence insertion of SPM-1 was replaced by the one present in Sfh-I. The chimeric variant is a selective cephalosporinase, revealing that the substrate profile of MBLs can be further tuned depending on the protein context. These results also show that the stable scaffold of MBLs allows a modular engineering much richer than the one observed in nature.Fil: GonzĂĄlez, Lisandro J.. Instituto de Biologia Molecular y Celular de Rosario; ArgentinaFil: Stival, Cintia EstefanĂa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂa Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de BiologĂa Molecular y Celular de Rosario; ArgentinaFil: Puzzolo, Juan Luis. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de QuĂmica Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de QuĂmica Rosario; ArgentinaFil: Moreno, Diego M.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de QuĂmica Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de QuĂmica Rosario; ArgentinaFil: Aguilar Vila, Alejandro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂa Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de BiologĂa Molecular y Celular de Rosario; Argentin
Enterocutaneous fistulas due to stent migration. How reliable is its use on duodenal benign pathology? a case report
Duodenal stenting has been widely used on malignant pathology on selected patients with poor prognosis and advanced disease. In these last years, there has been a clear ampliation of the clinical applications of endoscopy procedures and stents. Its use on benign pathology is spreading but there is a lack of literature about the complications in this context. The incidence of stent migration is about 10-25% in self-expandable metal stent (SEMS), and 2-5% on covered self-expanding metal stents (CSEMS). We reported a clinical case of a 48 years old patient who developed a duodenal ulcer. The patient was submitted to exploratory laparotomy, with duodenal primary closure of the ulcer. Later, the patient developed a enterocutaneous fistula because of the duodenal leak. It was referred to our third level hospital to the hepatopancreatobiliary surgery service. A new exploratory laparotomy with duodenal exclusion was planned, but it was impossible to access due to frozen abdomen. CSEMS was placed in the duodenal bulb resulting in the resolution of leaking, but the stent could not be removed because of migration. The stent trajectory was followed by abdominal x ray and tomography. The patient developed multiple intestinal an fecal enterocutaneous fistulas. It was submitted to multiples endoscopies, colonoscopies and enteroscopy without any success to reaching it. It was decided to perform a right lumbotomy to extract the prothesis. The stent was surgically removed, a planned stoma was left on the right flank on the extraction site
Climate tolerances of Philaenus spumarius should be considered in risk assessment of disease outbreaks related to Xylella fastidiosa
The bacterium Xylella fastidiosa (Xf) is an invasive insect-borne pathogen, which causes lethal diseases to important crops including olives, citrus, almonds and grapes as well as numerous forest, ornamental, and uncultivated plants. Outbreaks of Xf-related plant diseases are currently occurring in the Mediterranean region, causing substantial losses to various agricultural sectors. Several models have recently been published to identify which regions are at highest risk in Europe; however, such models did not consider the insect vectors, which constitute the key driver of short-range Xf spread. We fitted bioclimatic species distribution models to depict the macroclimatic preferences of the meadow spittlebug Philaenus spumarius L. (1978) (Hemiptera: Aphrophoridae), the major epidemiologically relevant vector currently responsible for Xf spread in the Europe. Many regions of Western Europe and Mediterranean basin are predicted by models as highly climatically suitable for this vector, including all regions where severe Xf have occurred so far. Conversely, the driest and warmest areas of the Mediterranean basin are predicted as little suitable for P. spumarius. Models forecast that agricultural-important parts of the southern Mediterranean area might experience a substantial decrease in climatic suitability for P. spumarius by the period 2040â2060. Areas predicted as highly suitable just for the bacterium but not optimal for this vector are apparently still free of severe Xf outbreaks, suggesting that climate tolerances of P. spumarius might partly explain the current spatial pattern of Xf outbreaks in Europe and should always be considered in further risk assessments.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work has been financially supported by the Spanish Ministerio de Ciencia, InnovaciĂłn y Universidades, Grant/Award Number: AGL2017-89604-R and the European Union Horizon 2020 research and innovation program under grant agreements no. 635646 POnTE (Pest Organisms Threatening Europe), and no. 727987 XF-ACTORS (Xylella Fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy). The first author of this study was funded by the fellowship âAyudas destinadas a la atracciĂłn de talento investigador de la Comunidad de Madridâ. Daniele Cornara participation in this work was supported by a research grant in the frame of European Unionâs Horizon 2020 research and innovation programme under the Marie SkĆodowska-Curie grant agreement No 835732 XYL-SPIT
Anomalies in Noncommutative Dipole Field Theories
We study chiral symmetries of fermionic non commutative dipole theories. By
using Fujikawa's approach we obtain explicit expressions of the anomalies for
Dirac and chiral fermions in 2 and 4 dimensions.Comment: 11pages, latex file. Comments adde
Epigenetics, bioelectricity and laterality of breast cancer
Epigenetics, Bioelectricity and Laterality of Breast CancerIn previous studies we found unexpectedly in patients that left-right (L-R) breast cancers (BC) differed in their methylation profiles (DM). We opened a new research line in which we hypothesize that, given the L-R environments of breast glands are non-identical: i. the bioelectric communication of the tumor with the L-R context differs, and ii. epigenetics has a crucial role in these differences. Our results, so far, are promising. We found in-silico that the top genes with L-R DM were involved in development, embryogenesis, and neural differentiation. We confirmed the same processes, by developing a MDA-MB231-Nod Scid Gama xenographt model and compared L-R tumoral methylation patterns by RRBS. With focus on ion channels, we found that depolarizing channels were more methylated R. This was suggesting that right sided tumors had a more polarized state as compared to left tumors. We setup an in-vitro model to treat MDA-MB231 cells with L-R conditioned extracts from normal human mammary glands and measured Ca2+ and ÎÏp with fluorescent probes. Cytometry assays confirmed bioelectric differences in the same direction: a more polarized state of right-treated cells. When deepening on epigenetic regulators, we found in-vitro a subtle increase of DNMT3 (de-novo methyltransferase) in left-treated cells, and confirmed it in-silico. Our studies support a non-explored epigenetic-bioelectric-laterality hypothesis for BC, which could serve as proof-of-principle for other bilateral tumors.Fil: Masuelli, SofĂa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Real, SebastiĂĄn. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Campoy, Emanuel Martin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Marzese, Diego MatĂas. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos; Argentina. Saint Johnâs Cancer Institute; Estados UnidosFil: Salomon, Matt. University of Southern California; Estados UnidosFil: de Blas, Gerardo AndrĂ©s. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Arias, Rodolfo JosĂ©. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Roque Moreno, Maria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias MĂ©dicas. Instituto de HistologĂa y EmbriologĂa de Mendoza Dr. Mario H. Burgos; ArgentinaBuenos Aires Breast Cancer SymposiumCiudad AutĂłnoma de Buenos AiresArgentinaConsejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FisiologĂa, BiologĂa Molecular y NeurocienciasConsejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de BiologĂa y Medicina ExperimentalCentro de EducaciĂłn MĂ©dica e Investigaciones ClĂnicasConsejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en Medicina TraslacionalConsejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Nanosistema
A transmembrane histidine kinase functions as a pH sensor
The two-component system DesK-DesR regulates the synthesis of unsaturated fatty acids in the soil bacteria Bacillus subtilis. This system is activated at low temperature and maintains membrane lipid fluidity upon temperature variations. Here, we found that DesKâthe transmembrane histidine kinaseâalso responds to pH and studied the mechanism of pH sensing. We propose that a helix linking the transmembrane region with the cytoplasmic catalytic domain is involved in pH sensing. This helix contains several glutamate, lysine, and arginine residues At neutral pH, the linker forms an alpha helix that is stabilized by hydrogen bonds in the i, i + 4 register and thus favors the kinase state. At low pH, protonation of glutamate residues breaks salt bridges, which results in helix destabilization and interruption of signaling. This mechanism inhibits unsaturated fatty acid synthesis and rigidifies the membrane when Bacillus grows in acidic conditions.Fil: Bortolotti, Ana. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de MicrobiologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: VĂĄzquez, Daniela BelĂ©n. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de MicrobiologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Almada, Juan Cruz. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de MicrobiologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Inda, MarĂa Eugenia. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de MicrobiologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Drusin, Salvador IvĂĄn. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y Farmaceuticas. Departamento de QuĂmica y FĂsica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Villalba, Juan Manuel. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de MicrobiologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Moreno, Diego Martin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de QuĂmica Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de QuĂmica Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y Farmaceuticas. Departamento de QuĂmica y FĂsica; ArgentinaFil: Ruysschaert, Jean Marie. Structure et Fonction des Membranes Biologiques; BĂ©lgicaFil: Cybulski, Larisa Estefania. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de MicrobiologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; Argentin
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