Thermal Degradation Of Sucralose: A Combination Of Analytical Methods To Determine Stability And Chlorinated Byproducts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)In the late years, much attention has been brought to the scientific community regarding the safety of sucralose and its industrial applications. Although it is the most used artificial sweetener in foods and pharmaceuticals, many questions still arise on its potential to form chlorinated byproducts in high temperatures, as demonstrated by several recent studies. In the present contribution, we use a combination of differential scanning calorimetry and thermogravimetric analysis coupled with infrared spectroscopy (DSC/TGA/IR), Hot-stage microscopy (HSM) and high-resolution mass spectrometry (HRMS) on samples submitted to water bath at mild temperatures to evaluate a broad spectrum of hazardous compounds formed in the degradation of this product. TGA/IR has revealed that there is effective decomposition in form of CO2 along with the formation of hydrogen chloride and other minor compounds. HSM results have provided accurate information, where the melting of the crystals was observed, followed by decomposition. Chlorinated derivatives, including polychlorinated aromatic hydrocarbons (PCAHs) were also confirmed by HRMS. These findings not only corroborate the suspected instability of sucralose to high temperatures, but also indicate that even exposed to mild conditions the formation of hazardous polychlorinated compounds is observed.5Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [11/50400-0, 14/00084-2

Physics of Psychophysics: Stevens and Weber-Fechner laws are transfer functions of excitable media

Sensory arrays made of coupled excitable elements can improve both their input sensitivity and dynamic range due to collective non-linear wave properties. This mechanism is studied in a neural network of electrically coupled (e.g. via gap junctions) elements subject to a Poisson signal process. The network response interpolates between a Weber-Fechner logarithmic law and a Stevens power law depending on the relative refractory period of the cell. Therefore, these non-linear transformations of the input level could be performed in the sensory periphery simply due to a basic property: the transfer function of excitable media.Comment: 4 pages, 5 figure

Uso del Tiempo en el Aula. Instituciones Educativas de nivel Secundaria 2013

El estudio arroja como resultados que en las aulas de quinto año de secundaria, a nivel nacional, las IIEE dedican aproximadamente el 70.6% del tiempo a actividades académicas. Mientras que el tiempo dedicado a actividades no académicas resultó ser de 29%. De este porcentaje, el 19.4% de las actividades estuvo destinada a la administración de la clase y de disciplina; y el 9.6% fue tiempo en el que el docente no se encontraba involucrado con la clase (por ejemplo, casos en los que el docente se encontraba fuera del aula)

Influence of environmental factors on tenuazonic acid production by Epicoccum sorghinum: An integrative approach of field and laboratory conditions

Sorghum is the fifth most cultivated and consumed grain in the world. However, this grain is frequently contaminated with toxins from fungi. The present study evaluated the effects of environmental factors on tenuazonic acid (TeA) production by Epicoccum sorghinum in the field and in controlled laboratory conditions. In this study, 50 sorghum grain samples were collected from summer and autumn growing seasons and analyzed for TeA contamination using LC-MS/MS. To further understand the ecophysiology of this fungus, an isolated strain of E. sorghinum from the field was investigated for its development and TeA production under controlled environmental conditions in the laboratory. In the ecophysiological investigation, the effects of water activity (0.90, 0.95, 0.99) and temperature (18, 22, 26 and 30?°C) were evaluated on the radial growth, enzymatic production and expression of TAS1, which is the gene involved in TeA production. Results showed that in the field, the summer season presented the highest TeA average level in the grains (587.8??g/kg) compared to level found in the autumn (440.5??g/kg). The ecophysiological investigation confirmed that E. sorghinum produces more actively TeA under environmental conditions simulating the summer season. Optimum growth, maximum TAS1 gene expression, and higher extracellular enzymatic production were observed at 26?°C with a water activity of 0.99. Pearson correlation analyses showed that the production of TeA highly correlates with fungal growth. The present study demonstrates that abiotic factors in a combined approach of field and laboratory conditions will assist in predicting the driving environmental factors that could affect growth of E. sorghinum and TeA production in sorghum grains

Método potencial para otimização de captura e manejo de abelhas nativas sem ferrão (Hymenoptera: Apidae: Meliponini) em iscas atrativas

Currently, pollinators are suffering an accelerated decline in their biodiversity due to factors such as pesticides, habitat loss, climate change and competition between exotic species. Bees are among the most important agents of pollination and those of the Meliponini tribe have been gaining prominence due to the spread of rational breeding practices. These practices can positively contribute to recreational, educational and commercial exploitation of the products produced. Despite widespread practices, and the various existing initiatives to regulate the creation and quality of honey, little has been proposed to improve techniques for obtaining colonies. In order to examine the potential use of an optimized technique for handling the removal of nests captured on attractive baits, a sheet of parchment paper was included as a coating inside two baits, in order to verify if this process does not interfere in obtaining the colony. and would facilitate its removal without damaging internal structures, improving handling. In the two attempts carried out, there was success in capturing swarms of the Jataí species (Tetragonisca angustula Latreille, 1811; Hymenoptera: Apidae: Meliponini) between three and five days after the installation of the bait. After the establishment of the swarm, the potential for the use of tracing paper was observed, which not only facilitated the handling and avoided the stress of the bees during the transfer but was even used for the construction of the nest by the bees of this species

Mass Spectrometry and Metabolomics—New Approaches for Helminth Biochemical Studies

Metabolomics, the study of the endogenously synthesized small molecules repertoire (nonproteinaceous), is of great relevance for establishing a wide view of cell physiology at specific moments, linking metabolic profiles to phenotypes and genotypes. To better understand biological systems, such as helminths life cycle, helminthic infection, and host-parasite interaction, metabolomics studies are crucial. For that, mass spectrometry-based metabolomics is the most popular strategy. Nontargeted metabolomics allows researchers to profile entire metabolomes present in cells, tissues, biofluids, or even samples as complex as stools. Through different mass spectrometric techniques, it is possible to unveil chemical markers for helminths, such as Schistosoma mansoni (a trematode) and Ascaris lumbricoides (a nematode), in addition to study mechanisms of action for different drugs, which targets parasites. Therefore, mass spectrometry allows designing biochemical pathways that may clarify the processes of parasite life cycle, helminthic infection, and host-parasite interaction, providing targets to further interference for parasite control or even infection treatment

Resolving the fine structure in the energy landscapes of repeat proteins

Ankyrin (ANK) repeat proteins are coded by tandem occurrences of patterns with around 33 amino acids. They often mediate protein–protein interactions in a diversity of biological systems. These proteins have an elongated non-globular shape and often display complex folding mechanisms. This work investigates the energy landscape of representative proteins of this class made up of 3, 4 and 6 ANK repeats using the energy-landscape visualisation method (ELViM). By combining biased and unbiased coarse-grained molecular dynamics AWSEM simulations that sample conformations along the folding trajectories with the ELViM structure-based phase space, one finds a three-dimensional representation of the globally funnelled energy surface. In this representation, it is possible to delineate distinct folding pathways. We show that ELViMs can project, in a natural way, the intricacies of the highly dimensional energy landscapes encoded by the highly symmetric ankyrin repeat proteins into useful low-dimensional representations. These projections can discriminate between multiplicities of specific parallel folding mechanisms that otherwise can be hidden in oversimplified depictions.M.N.S. was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; Grant 130147/2020-6). This research was supported by the Center for Theoretical Biological Physics sponsored by the NSF (Grant PHY-2019745). A.B.O. acknowledges the Robert A. Welch Postdoctoral Fellow program. P.G.W. is also supported by the D.R. Bullard-Welch Chair at Rice University (Grant C-0016). V.B.P.L. was supported by CNPq (Grant 310017/2020-3) and FAPESP (Grants 2019/22540-3 and 2018/18668-1). D.U.F. is a CONICET researcher and is supported by Grant PICT2016/1467, UBACYT, and NASA Astrobiology Institute-Enigma (Grant 80NSSC18M0093).Peer ReviewedPostprint (published version

Coenzyme Q10 or Creatine Counteract Pravastatin-Induced Liver Redox Changes in Hypercholesterolemic Mice

Statins are the preferred therapy to treat hypercholesterolemia. Their main action consists of inhibiting the cholesterol biosynthesis pathway. Previous studies report mitochondrial oxidative stress and membrane permeability transition (MPT) of several experimental models submitted to diverse statins treatments. The aim of the present study was to investigate whether chronic treatment with the hydrophilic pravastatin induces hepatotoxicity in LDL receptor knockout mice (LDLr-/-), a model for human familial hypercholesterolemia. We evaluated respiration and reactive oxygen production rates, cyclosporine-A sensitive mitochondrial calcium release, antioxidant enzyme activities in liver mitochondria or homogenates obtained from LDLr-/- mice treated with pravastatin for 3 months. We observed that pravastatin induced higher H2O2 production rate (40%), decreased activity of aconitase (28%), a superoxide-sensitive Krebs cycle enzyme, and increased susceptibility to Ca2+-induced MPT (32%) in liver mitochondria. Among several antioxidant enzymes, only glucose-6-phosphate dehydrogenase (G6PD) activity was increased (44%) in the liver of treated mice. Reduced glutathione content and reduced to oxidized glutathione ratio were increased in livers of pravastatin treated mice (1.5- and 2-fold, respectively). The presence of oxidized lipid species were detected in pravastatin group but protein oxidation markers (carbonyl and SH- groups) were not altered. Diet supplementation with the antioxidants CoQ10 or creatine fully reversed all pravastatin effects (reduced H2O2 generation, susceptibility to MPT and normalized aconitase and G6PD activity). Taken together, these results suggest that 1- pravastatin induces liver mitochondrial redox imbalance that may explain the hepatic side effects reported in a small number of patients, and 2- the co-treatment with safe antioxidants neutralize these side effects