52 research outputs found
Evaluation of an alternative spectroscopic approach for aflatoxin analysis: Comparative analysis of food and feed samples with UPLC-MS/MS
Increasing research has highlighted the effects of changing climates on the occurrence and prevalence of toxigenic Aspergillus species producing aflatoxins. There is concern of the toxicological effects to human health and animal productivity following acute and chronic exposure that may affect the future ability to provide safe and sufficient food globally. Considerable research has focused on the detection of these toxins, based on the physicochemical and biochemical properties of the aflatoxin compounds, in agricultural products for human and animal consumption. As improvements in food security continue more regulations for acceptable levels of aflatoxins have arisen globally; the most stringent in Europe. These regulations are important for developing countries as aflatoxin occurrence is high significantly effecting international trade and the economy. In developed countries analytical approaches have become highly sophisticated, capable of attaining results with high precision and accuracy, suitable for regulatory laboratories. Regrettably, many countries that are affected by aflatoxin contamination do not have resources for high tech HPLC and MS instrumentation and require more affordable, yet robust equally accurate alternatives that may be used by producers, processors and traders in emerging economies. It is especially important that those companies wishing to exploit the opportunities offered by lucrative but highly regulated markets in the developed world, have access to analytical methods that will ensure that their exports meet their customers quality and safety requirements. This work evaluates the ToxiMet system as an alternative approach to UPLCâMS/MS for the detection and determination of aflatoxins relative to current European regulatory standards. Four commodities: rice grain, maize cracked and flour, peanut paste and dried distillers grains were analysed for natural aflatoxin contamination. For B1 and total aflatoxins determination the qualitative correlation, above or below the regulatory limit, was good for all commodities with the exception of the dried distillers grain samples for B1 for which no calibration existed. For B1 the quantitative R2 correlations were 0.92, 0.92, 0.88 (<250 ÎŒg/kg) and 0.7 for rice, maize, peanuts and dried distillers grain samples respectively whereas for total aflatoxins the quantitative correlation was 0.92, 0.94, 0.88 and 0.91. The ToxiMet system could be used as an alternative for aflatoxin analysis for current legislation but some consideration should be given to aflatoxin M1 regulatory levels for these commodities considering the high levels detected in this study especially for maize and peanuts. (RĂ©sumĂ© d'auteur
G protein-coupled receptor-mediated calcium signaling in astrocytes
Astrocytes express a large variety of G~protein-coupled receptors (GPCRs)
which mediate the transduction of extracellular signals into intracellular
calcium responses. This transduction is provided by a complex network of
biochemical reactions which mobilizes a wealth of possible calcium-mobilizing
second messenger molecules. Inositol 1,4,5-trisphosphate is probably the best
known of these molecules whose enzymes for its production and degradation are
nonetheless calcium-dependent. We present a biophysical modeling approach based
on the assumption of Michaelis-Menten enzyme kinetics, to effectively describe
GPCR-mediated astrocytic calcium signals. Our model is then used to study
different mechanisms at play in stimulus encoding by shape and frequency of
calcium oscillations in astrocytes.Comment: 35 pages, 6 figures, 1 table, 3 appendices (book chapter
Tecnologia e administração de recursos humanos: uma anĂĄlise crĂtica da implantação de sistemas integrados de gestĂŁo em uma cooperativa agro-industrial
Gi/o-protein coupled receptors in the aging brain
Cells translate extracellular signals to regulate processes such as differentiation, metabolism and proliferation, via transmembranar receptors. G protein-coupled receptors (GPCRs) belong to the largest family of transmembrane receptors, with over 800 members in the human species. Given the variety of key physiological functions regulated by GPCRs, these are main targets of existing drugs. During normal aging, alterations in the expression and activity of GPCRs have been observed. The central nervous system (CNS) is particularly affected by these alterations, which results in decreased brain functions, impaired neuroregeneration, and increased vulnerability to neuropathologies, such as Alzheimer's and Parkinson diseases. GPCRs signal via heterotrimeric G proteins, such as Go, the most abundant heterotrimeric G protein in CNS. We here review age-induced effects of GPCR signaling via the Gi/o subfamily at the CNS. During the aging process, a reduction in protein density is observed for almost half of the Gi/o-coupled GPCRs, particularly in age-vulnerable regions such as the frontal cortex, hippocampus, substantia nigra and striatum. Gi/o levels also tend to decrease with aging, particularly in regions such as the frontal cortex. Alterations in the expression and activity of GPCRs and coupled G proteins result from altered proteostasis, peroxidation of membranar lipids and age-associated neuronal degeneration and death, and have impact on aging hallmarks and age-related neuropathologies. Further, due to oligomerization of GPCRs at the membrane and their cooperative signaling, down-regulation of a specific Gi/o-coupled GPCR may affect signaling and drug targeting of other types/subtypes of GPCRs with which it dimerizes. Gi/o-coupled GPCRs receptorsomes are thus the focus of more effective therapeutic drugs aiming to prevent or revert the decline in brain functions and increased risk of neuropathologies at advanced ages.This work was supported by Fundação para a CiĂȘncia e
Tecnologia, Centro 2020 and Portugal 2020, the COMPETE
program, QREN, and the European Union (FEDER program)
via the GoBack project (PTDC/CVT-CVT/32261/2017),
the pAGE program (Centro-01-0145-FEDER-000003), and
Institute for Biomedicine iBiMED (UID/BIM/04501/2013;
UID/BIM/04501/2019).publishe
Induction of type IPACAP receptor expression by the new zinc finger protein Zac1 and p53
Cooccurrence of mycotoxins in maize and poultry feeds from Brazil by liquid chromatography/tandem mass spectrometry.
The objective of this study was to quantitatively evaluate mycotoxins in samples of maize and poultry feed produced in Brazil. A multimycotoxin method based on HPLC-MS/MS was applied to investigate the occurrence of toxical fungal metabolites in 119 samples collected from poultry feed factory integrated poultry farms: maize grain (74), poultry feed (36), and feed factory residue (9). Twenty of 101 fungal metabolites investigated were detected and quantified in the samples: aflatoxins B1, B2, G1, and G2, fumonisins B1, B2, and B3, hydrolyzed fumonisin B1, zearalenone, agroclavine, chanoclavine, deoxynivalenol, and nivalenol, and enniatin A, A1, B, B1, beauvericin, kojic acid, and moniliformin. Most samples were contaminated with more than one mycotoxin. All samples were contaminated with fumonisins, with medians values of 1,840âÎŒg/kg, 239âÎŒg/kg, and 23,676âÎŒg/kg for maize, feed, and factory residue samples, respectively. Surprisingly, beauvericin was detected in more than 90% of samples. The median contaminations of aflatoxin and trichothecenes were low, near LOD values. The factory residue presented highest contamination levels for all mycotoxins. This is the first study dealing with agroclavine, chanoclavine, enniatin A, A1, B, B1, beauvericin, and kojic acid contamination of maize and poultry feeds from Brazil
Synthesis and preliminary evaluation of (S)-2-(4'-carboxycubyl)glycine, a new selective mGluR1 antagonist.
DÂČBIOFRUITS - DĂ©veloppement de mĂ©thodologies d'Ă©valuation des pertes post-rĂ©colte et Ă©tude de lâefficacitĂ© de procĂ©dĂ©s compatibles avec l'agriculture biologique pour dĂ©sinfecter et dĂ©sinsectiser les fruits. Innovations
Les recherches menĂ©es dans le cadre du projet DÂČBIOFRUITS ont portĂ© sur quatre espĂšces de fruits jugĂ©es sensibles aux pertes : la pĂȘche, la mangue, la chĂątaigne et le raisin de table. Dans une premiĂšre action, des mĂ©thodologies de quantification et dâĂ©valuation des causes de pertes dans la filiĂšre fruits et lĂ©gumes frais ont Ă©tĂ© dĂ©veloppĂ©s grĂące Ă des diagnostics dâentreprises et lâidentification des processus clĂ©s. Une mĂ©thode dâidentification des maladies de la chĂątaigne et un outil pour anticiper les pertes pour le raisin de table ont Ă©galement Ă©tĂ© mis au point. Les autres travaux ont portĂ© sur lâĂ©valuation de mĂ©thodes physiques (traitements thermiques, atmosphĂšre contrĂŽlĂ©e, anoxie, UV-C) ou faisant appel Ă des produits de biocontrĂŽle (levure antagoniste et huiles essentielles). Les mĂ©thodes physiques se sont rĂ©vĂ©lĂ©es ĂȘtre les plus efficaces pour lutter contre le dĂ©veloppement des pourritures ou dĂ©truire dâĂ©ventuels insectes Ă lâintĂ©rieur des fruits et certaines peuvent ĂȘtre rapidement transfĂ©rĂ©es Ă grande Ă©chelle. Lâapplication de la levure antagoniste Metschnikowia fructicola ou dâhuiles essentielles a montrĂ© une efficacitĂ© in vitro sur les champignons responsables des pourritures des fruits mais cette efficacitĂ© nâa pas Ă©tĂ© confirmĂ©e lors dâune application sur fruits aprĂšs rĂ©colte
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