Antibacterial Activity of New Oxazolidin-2-One Analogues in Methicillin-Resistant Staphylococcus aureus Strains

Staphylococcus aureus is one of the most common causes of nosocomial infections. The purpose of this study was the synthesis and in vitro evaluation of antimicrobial activity of 10 new 3-oxazolidin-2-one analogues on 12 methicillin resistant S. aureus (MRSA) clinical isolates. S. aureus confirmation was achieved via catalase and coagulase test. Molecular characterization of MRSA was performed by amplification of the mecA gene. Antimicrobial susceptibility was evaluated via the Kirby-Bauer disc diffusion susceptibility test protocol, using commonly applied antibiotics and the oxazolidinone analogues. Only (R)-5-((S)-1-dibenzylaminoethyl)-1,3-oxazolidin-2-one (7a) exhibited antibacterial activity at 6.6 μg. These results, allow us to infer that molecules such as 7a can be potentially used to treat infections caused by MRSA strains.     

Experimental methods in chemical engineering: Thermogravimetric analysis—TGA

Thermogravimetric analysis (TGA) is a quantitative analytical technique that monitors the mass of a sample from 1 mg to several g as a furnace ramps temperature to as high as 1600°C under a stable or changing gas flow. The first gravimetric test was in 27 BC when Vitruvius measured limestone's change of mass as it calcined to lime. In modern chemical engineering, researchers apply the technique to derive conversions, kinetics, and mechanisms for any process with a change of mass by isothermal, non-isothermal, and quasi-isothermal methods. The mass drops as the sample decomposes, volatile compounds evaporate, or the oxidation state decreases, while in reactive environments (with O₂, for example), the mass of transition metals may increase. TGA is incapable of detecting phase transitions, polymorphic transformations, or reactions for which mass is invariant. DSC or DTA couple with TGA to help deconvolute a DSC plot by separating physical changes from chemical changes. Evolved gas analysis techniques monitor the gaseous products exiting the TGA furnace on-line as the temperature ramps. A bibliometric map of keywords from articles citing TGA indexed by Web of Science in 2016 and 2017 identified five research clusters: nanoparticles, performance, and films; crystal structures, acid, and oxidation; composites, nanocomposites, and mechanical properties; kinetics, pyrolysis, and temperature; and adsorption, water and wastewater, and aqueous solutions. This review provides an overview of the basic principles of modern TGA.     

Do networking centres perform better? An exploratory analysis in Psychiatry and Gastroenterology/Hepatology in Spain

Science has become progressively more complex, requiring greater integration and collaboration between individuals, institutions and areas. Networking research establishes common rules and offers a suitable framework for this cooperation. Therefore, it is a good choice for both scientists and policy-makers. The objective of this study is to know whether the scientists perform better within these structures than outside them. As an example, we analysed the Biomedical Research Networking Centres in Spain and, for the exploratory investigation, we selected two disciplines (Psychiatry and Gastroenterology/Hepatology). The results showed that in every situation of networking research there were higher collaboration and impact rates. Furthermore, the main differences found between disciplines were related to the scope of cooperation, carried out at a more local level in Gastroenterology/Hepatology. Besides, HJ-Biplot technique allowed us to conclude that the outcomes may vary somewhat depending on the types of centres where the scientists work. Although further investigation is needed, the findings of this study might anticipate possible scenarios in which networking research could be the most natural way of collaboration.     

Influence of winemaking techniques on proanthocyanidin extraction in Monastrell wines from four different areas

The effect of two low pre-fermentative temperature techniques (cold soak and must freezing with dry ice) using two macerating enzymes was studied during the vinification of Monastrell wines from four different areas (Cañada del Judío, Cañada de Albatana, Montealegre and Chaparral) belonging to two Denomination of Origins (Jumilla and Bullas), to assess their influence on wine proanthocyanidin concentration and composition. When the control wines were compared, Chaparral wine showed the lowest proanthocyanidin content, together with the lowest mDP and the highest degree of galloylation in its proanthocyanidins, suggesting that the most of the proanthocyanidins in wine had been extracted from the grape seeds. However, Cañada de Albatana wines showed the highest proanthocyanidin content. Different results were found in the four areas when the oenological treatments were applied to the grapes. In Cañada de Albatana wines, no treatment had any effect, while in the case of Montealegre wines, the cold treatments led to a higher proanthocyanidin content compared with the control wines. In Cañada del Judío and Chaparral wines, all the treatments increased the proanthocyanidin content, except when galactoside was used in Chaparral wines, when the results were even lower than for the control wines. Discriminant analyses were applied to check whether the different areas influenced the wine proanthocyanidin profile. The results showed a clear separation between the four plots, suggesting that the proanthocyanidin wine composition was related to the zone where grapes were cultivated.     

Bioavailability of a Heme-Iron Concentrate Product Added to Chocolate Biscuit Filling in Adolescent Girls Living in a Rural Area of Mexico

ABSTRACT: A heme-iron concentrate product derived from swine hemoglobin was used to enrich the chocolate-flavored filling of biscuits and the bioavailability of this source of heme-iron was assessed in adolescent girls. The placebo control (PC) group consisted of 35 teenagers with the highest baseline hemoglobin concentrations. The supplemented groups were randomized to receive biscuits fortified with iron sulfate (IS, n = 37) or heme-iron concentrate (HIC, n = 40). Both groups were supplemented with 10.3 mg Fe/d for 7 wk. Blood chemistry and hematology analyses were performed at baseline and at the end of the study. The baseline prevalence of anemia (hemoglobin <12g/dl) in the entire group was 3.9% and by the end of the study it had fallen to 2.3%. The hemoglobin levels in both supplemented groups increased (P < 0.05) during the study period from 13.6 and 13.5 g/dl for HIC and IS, respectively, at baseline to 14 g/dl at the end of the study. Serum ferritin concentrations decreased by the end of the study in both the PC and IS groups (P < 0.05), but not in the heme group. In conclusion, iron bioavailability from HIC-fortified biscuits was calculated to be 23.7% higher than that observed for IS, as shown by the differences observed in serum ferritin levels during the study. The iron contained in the heme-iron concentrate was well absorbed and tolerated by the adolescents included in the study.     

Theoretical Investigation of Hydrogen Adsorption and Dissociation on Iron and Iron Carbide Surfaces Using the ReaxFF Reactive Force Field Method

We have developed a ReaxFF reactive force field to describe hydrogen adsorption and dissociation on iron and iron carbide surfaces relevant for simulation of Fischer?CTropsch (FT) synthesis on iron catalysts. This force field enables large system (>>1000 atoms) simulations of hydrogen related reactions with iron. The ReaxFF force field parameters are trained against a substantial amount of structural and energetic data including the equations of state and heats of formation of iron and iron carbide related materials, as well as hydrogen interaction with iron surfaces and different phases of bulk iron. We have validated the accuracy and applicability of ReaxFF force field by carrying out molecular dynamics simulations of hydrogen adsorption, dissociation and recombination on iron and iron carbide surfaces. The barriers and reaction energies for molecular dissociation on these two types of surfaces have been compared and the effect of subsurface carbon on hydrogen interaction with iron surface is evaluated. We found that existence of carbon atoms at subsurface iron sites tends to increase the hydrogen dissociation energy barrier on the surface, and also makes the corresponding hydrogen dissociative state relatively more stable compared to that on bare iron. These properties of iron carbide will affect the dissociation rate of H₂ and will retain more surface hydride species, thus influencing the dynamics of the FT synthesis process.