Vibrational study and force field of the citric acid dimer based on the SQM methodology

We have carried out a structural and vibrational theoretical study for the citric acid dimer. The Density Functional Theory (DFT) method with the B3LYP/6-31G() and B3LYP/6-311++ G methods have been used to study its structure and vibrational properties. Then, in order to get a good assignment of the IR and Raman spectra in solid phase of dimer, the best fit possible between the calculated and recorded frequencies was carry out and the force fields were scaled using the Scaled Quantum Mechanic Force Field (SQMFF) methodology. An assignment of the observed spectral features is proposed. A band of medium intensity at 1242 cm - 1 together with a group of weak bands, previously not assigned to the monomer, was in this case assigned to the dimer. Furthermore, the analysis of the Natural Bond Orbitals (NBOs) and the topological properties of electronic charge density by employing Bader's Atoms in Molecules theory (AIM) for the dimer were carried out to study the charge transference interactions of the compound.Facultad de Ciencias Exacta

Detection of acylhomoserine lactones in cultures of Gluconacetobacter diazotrophicus PAL5

Gluconacetobacter diazotrophicus is an acid-tolerant nitrogen- fixing Alphaproteobacterium first found in association with sugarcane. It has also been isolated from rice, coffee and tea, among others crops. The recent sequencing of the G. diazotrophicus PAL5 genome shows the presence of one luxI homolog. These genes encode LuxI-type enzymes responsible for the synthesis of N- acylhomoserine lactones (AHLs), the main quorum sensing molecules in gram negative bacteria. The objective of this work was the detection and identification of AHLs produced by G. diazotrophicus PAL5. The strain was cultured aerobically, and extracts were prepared with acidified ethyl acetate. Samples were analyzed by thin layer chromatography developed with the biosensor Agrobacterium tumefaciens NTL4 (pCF218) (pCF372). Results show that G. diazotrophicus PAL5 produce at least two types of AHLs under the assayed conditions. Short-chain AHLs could be detected since early exponential growth phase, and medium-chain AHLs were detected in mid- and late-exponential growth phase. The results suggest that the luxI homolog in G. diazotrophicus PAL5 is expressed and quorum sensing molecules are produced and secreted. Similar to other bacteria, production of AHLs in G. diazotrophicus PAL5 could serves as a signaling mechanism among members of this genus or as inter kingdom signals.Fil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Bichara, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Marino, Damian Jose Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigaciones del Medio Ambiente - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones del Medio Ambiente; ArgentinaFil: Castellanos, Lucia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Irazusta, Verónica Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología MolecularPuerto MadrynArgentinaSociedad Argentina de Investigación en Bioquímica y Biología Molecula

Vibrational study and force field of the citric acid dimer based on the SQM methodology

We have carried out a structural and vibrational theoretical study for the citric acid dimer. The Density Functional Theory (DFT) method with the B3LYP/6-31G() and B3LYP/6-311++ G methods have been used to study its structure and vibrational properties. Then, in order to get a good assignment of the IR and Raman spectra in solid phase of dimer, the best fit possible between the calculated and recorded frequencies was carry out and the force fields were scaled using the Scaled Quantum Mechanic Force Field (SQMFF) methodology. An assignment of the observed spectral features is proposed. A band of medium intensity at 1242 cm - 1 together with a group of weak bands, previously not assigned to the monomer, was in this case assigned to the dimer. Furthermore, the analysis of the Natural Bond Orbitals (NBOs) and the topological properties of electronic charge density by employing Bader's Atoms in Molecules theory (AIM) for the dimer were carried out to study the charge transference interactions of the compound.Facultad de Ciencias Exacta

Density Functional Theory Calculations of the Molecular Force Field of l -Ascorbic Acid, Vitamin C

We have studied l-ascorbic acid and characterized it by infrared spectroscopy in solid and aqueous solution phases. The density functional theory (DFT) method together with Pople’s basis set show that three stable molecules for the compound have been theoretically determined in the gas phase, and that an average of only two more stable conformations are present in the solid phase, as it was experimentally observed. The harmonic vibrational wavenumbers for the optimized geometries of both structures were calculated at B3LYP/6-31G*and B3LYP/6-311++G** levels at the proximity of the isolated molecule. For a complete assignment of the vibrational spectra in the compound solid and aqueous solution phases, DFT calculations were combined with Pulay’s scaled quantum mechanics force field methodology in order to fit the theoretical wavenumber values to the experimental ones. In this way, a complete assignment of all the observed bands in the infrared spectrum for l-ascorbic acid was performed. The natural bond orbital study reveals the characteristics of the electronic delocalization of the three structures while the corresponding topological properties of electronic charge density are analyzed by employing Bader’s atoms-in-molecules theory.Fil: Bichara, Laura Cecilia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; ArgentinaFil: Lanús, Hernán Enrique. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; ArgentinaFil: Brandan, Silvia Antonia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Física; Argentin

Early hemodynamic and biochemical markers for metabolic risk in children with a background of intrauterine growth restriction

El bajo peso al nacer (BPN) se asocia a riesgo cardiovascular y metabólico futuro.Sin embargo, no existen marcadores tempranos, hemodinámicos y bioquímicos,en niños con BPN que ayuden a prevenir las complicaciones posteriores al nacimiento. Mas aún, existe escasa evidencia sobre la relación de la función vasculary su asociación con el BPN y alteraciones metabólicas como posibles marcadorestempranos. Objetivo: Estudiar variables bioquímicas, antropométricas y hemodinámicas en niños con antecedentes de BPN. Métodos: En niños de 7 añosde edad, de ambos sexos, con y sin antecedentes de BPN (BPN, n=17 vs grupocontrol, n=5), que concurren al Hospital del Niño Jesús (Tucumán) se hicieron lassiguientes determinaciones: peso, talla, índice de masa corporal (IMC), y perímetros de cuello y cintura. Se midió las presiones arteriales sistólica (PAS), diastólica(PAD) y media (PAM) y la frecuencia cardiaca (FC). Se evaluó la función endotelial (FE) por método no invasivo de hiperemia reactiva. Además, se determinó elperfil lipídico, glucemia, insulinemia y resistencia a la insulina. Resultados: Elgrupo BPN presentó una importante tendencia de aumento de peso (grupo control: 23±1 kg vs BPN: 31±3 kg; p=0.09; percentil de 15 y 85 respectivamente),aunque sin significancia estadística. Similarmente, no se encontró diferenciasen talla, IMC, perímetros de cuello y cintura. En ambos grupos el percentil de PAfue <95. Sin embargo, BPN presentó mayor PAS (grupo control: 85±1 mmHg vsBPN:97±1; p<0,05), PAD (grupo control: 52±1 mmHg vs BPN:61±1; p<0,05) yPAM, sin diferencias en la FC. BPN presentó menor FE comparado a los controles(p<0.05). Además, se observó una correlación positiva entre el BPN con la PAS yla FE. Finalmente, se observó una asociación entre la resistencia a la insulina y laPAS. Conclusiones: En los niños con BPN, hubo un aumento en los marcadoreshemodinámicos de PAS, PAD, y PAM a pesar de estar en el percentil de la normalidad. Además, fue acompañado por una reducción en FE. Entre los marcadoresbioquímicos, los niveles de insulina con una correlación positiva con TG mostraron verse afectados en las primeras etapas de la vida. Además, BPN se correlacionó positivamente con la PAS. Estos resultados sugieren que hay marcadoreshemodinámicos y bioquímicos tempranos de riesgo cardiovascular y metabólicoa futuro. Además, indica que la resistencia a la insulina podría desempeñar unpapel en el aumento de la presión arterial en BPN. Futuros estudios son necesarios para la confirmación de estas observaciones y la implementación de alternativas terapéuticas a una edad temprana.Low birth weight (LBW) is associated with future cardiovascular and metabolic risk. However, there are no early, hemodynamic and biochemical markers in children with LBW that help prevent post-birth complications. Moreover, there is little evidence on the relationship between vascular function and its association with LBW and metabolic alterations as possible early markers. Aim: To study the biochemical, anthropometric, and hemodynamic parameters in children with a history of BPN. Methods: In children aged seven years, both sexes, with and without a history of LBW (LBW, n=17 vs. control group, n=5), who attend the Hospital del Niño Jesús (Tucumán) the following determinations were made: weight, height, body mass index (BMI), and neck and waist circumferences. Blood pressure was measured as systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP), and also heart rate (HR) was registered. Endothelial function (EF) was evaluated by the non-invasive method of reactive hyperemia. Also, lipid profile, blood glucose, insulinemia, and insulin resistance were determined. Results: The LBW group presented an important trend of weight gain (control group: 23±1 kg vs. LBW: 31±3 kg; p=0.09; percentile of 15 and 85 respectively), although without statistical significance. Similarly, no differences were found in height, BMI, neck, and waist circumferences. In both groups, the BP percentile was <95. However, LBW had higher SBP (control group: 85±1 mmHg vs LBW: 97±1; p<0.05), DBP (control group: 52±1 mmHg vs LBW: 61±1; p<0.05) and MAP, with no differences in HR. LBW had lower EF compared to controls (p<0.05). In addition, a positive correlation was observed between LBW and SBP and EF. Finally, an association between insulin resistance and SBP was observed. Conclusions: In children with LBW, there was an increase in hemodynamic markers such as SBP, DBP, and MAP despite being in the percentile of normality. Besides, it was accompanied by a reduction in EF. Among biochemical markers, insulin levels and TG showed to be affected early in life. In addition, LBW was positively correlated with SBP and EF. These results suggest that there are early hemodynamic and biochemical markers for future cardiovascular and metabolic risk. Also, it indicates that insulin may play a role in the increases in blood pressure in LBW. Future studies are necessary for the confirmation of these observations and the implementation of therapeutic alternatives at an early age of life.Fil: Peral, Maria de Los Angeles. Universidad Nacional de Tucumán. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto Superior de Investigaciones Biológicas. Grupo de Investigación y Desarrollo del Noroeste Argentino | Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas. Grupo de Investigación y Desarrollo del Noroeste Argentino; ArgentinaFil: Marañón, Rodrigo Oscar. Universidad Nacional de Tucumán. Facultad de Medicina; ArgentinaFil: Joo Turoni, Claudio Martín. Universidad Nacional de Tucumán. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto Superior de Investigaciones Biológicas. Grupo de Investigación y Desarrollo del Noroeste Argentino | Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas. Grupo de Investigación y Desarrollo del Noroeste Argentino; ArgentinaFil: Bichara, Laura Cecilia. Universidad Nacional de Tucumán. Facultad de Medicina; Argentina. Servicio Endocrinología Hospital del Niño Jesús Tucumán; ArgentinaFil: Chahla, Rossana. Provincia de Tucuman. Ministerio de Salud; ArgentinaFil: Chaila, Maria Zulema. Universidad Nacional de Tucumán. Facultad de Medicina; ArgentinaFil: Simesen de Bielke, Maria Gabriela. Universidad Nacional de Tucumán. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Cristiani, Jorge. Universidad Nacional de Tucumán. Facultad de Medicina; ArgentinaFil: Elias, A. Universidad Nacional de Tucumán. Facultad de Medicina; ArgentinaFil: Graiff, O.. Universidad Nacional de Tucumán. Facultad de Medicina; ArgentinaFil: Bazan de Casella, María Cristina del Valle. Universidad Nacional de Tucumán. Facultad de Medicina; Argentin