81 research outputs found
Contractile Response of Bovine Lateral Saphenous Vein to Ergotamine Tartrate Exposed to Different Concentrations of Molecularly Imprinted Polymer
Ergot alkaloids, in their active isomeric form, affect animal health and performance, and adsorbents are used to mitigate toxicities by reducing bioavailability. Adsorbents with high specificity (molecularly imprinted polymers: MIP) adsorb ergot alkaloids in vitro, but require evaluation for biological implications. Using ex vivo myography, synthetic polymers were evaluated for effects on the bioactivity of ergotamine tartrate (ETA). Polymers were first evaluated using isotherms. Lateral saphenous veins were collected from 17 steers for four independent studies: dose response of ETA, adsorbent dose response, validation of pre-myograph incubation conditions and MIP/ non-molecularly imprinted polymer (NIP) comparison. Norepinephrine normalized percent contractile response to increasing ETA exhibited a sigmoidal dose response (max: 88.47 and log of the effective molar concentration (EC50) (âlog [ETA]) of 6.66 ± 0.17 M). Although sample preparation time affected contractile response (p \u3c 0.001), pre-myograph incubation temperature (39 vs. 21 °C, 1 h) had no effect (p \u3e 0.05). Isothermal adsorption showed a maximum adsorption of 3.27E-008 moles·mgâ1 and affinity between 0.51 and 0.57 mg (R2: 0.83â0.92) for both polymers, with no significant difference between polymers (p \u3e 0.05). No significant differences in maximum inhibitory (p = 0.96) and IC50 responses (p = 0.163) between MIP and NIP were noticed. Normalized percent contraction could be predicted from the in vitro adsorption data (R2 = 0.87, p\u3c 0.01), for both polymers. These studies indicate that synthetic polymers are potentially effective adsorbents to mitigate ergot toxicity caused by ergot alkaloids, with little evidence of significant differences between MIP and NIP in aqueous media
Effects of Adipocyte Aryl Hydrocarbon Receptor Deficiency on PCB-Induced Disruption of Glucose Homeostasis in Lean and Obese Mice
BACKGROUND: Coplanar polychlorinated biphenyls (PCBs) promote adipocyte inflammation and impair glucose homeostasis in lean mice. The diabetes-promoting effects of lipophilic PCBs have been observed only during weight loss in obese mice. The molecular mechanisms linking PCB exposures to impaired glucose metabolism are unclear.
OBJECTIVES: In this study we tested the hypothesis that coplanar PCBs act at adipocyte aryl hydrocarbon receptors (AhRs) to promote adipose inflammation and impair glucose homeostasis in lean mice and in obese mice during weight loss.
METHODS AND RESULTS: PCB-77 administration impaired glucose and insulin tolerance in LF (low fat diet)-fed control (AhRfl/fl) mice but not in adipocyte AhR-deficient mice (AhRAdQ). Unexpectedly, AhRAdQ mice exhibited increased fat mass when fed a standard LF or high fat (HF) diet. In mice fed a HF diet, both genotypes became obese, but AhRAdQ mice administered vehicle (VEH) exhibited increased body weight, adipose mass, adipose inflammation, and impaired glucose tolerance compared with AhRfl/fl controls. Impairment of glucose homeostasis in response to PCB-77 was not observed in obese mice of either genotype. However, upon weight loss, AhRfl/fl mice administered PCB-77 exhibited increased abundance of adipose tumor necrosis factor-α (TNF-α) mRNA and impaired glucose homeostasis compared with those administered VEH. In contrast, PCB-77 had no effect on TNF-α or glucose homeostasis in AhRAdQ mice exhibiting weight loss.
CONCLUSIONS: Our results demonstrate that adipocyte AhR mediates PCB-induced adipose inflammation and impairment of glucose homeostasis in mice. Moreover, deficiency of AhR in adipocytes augmented the development of obesity, indicating that endogenous ligand(s) for AhR regulate adipose homeostasis
Adipose-Specific PPARα Knockout Mice Have Increased Lipogenesis by PASKâSREBP1 Signaling and a Polarity Shift to Inflammatory Macrophages in White Adipose Tissue
The nuclear receptor PPARα is associated with reducing adiposity, especially in the liver, where it transactivates genes for ÎČ-oxidation. Contrarily, the function of PPARα in extrahepatic tissues is less known. Therefore, we established the first adipose-specific PPARα knockout (PparaFatKO) mice to determine the signaling position of PPARα in adipose tissue expansion that occurs during the development of obesity. To assess the function of PPARα in adiposity, female and male mice were placed on a high-fat diet (HFD) or normal chow for 30 weeks. Only the male PparaFatKO animals had significantly more adiposity in the inguinal white adipose tissue (iWAT) and brown adipose tissue (BAT) with HFD, compared to control littermates. No changes in adiposity were observed in female mice compared to control littermates. In the males, the loss of PPARα signaling in adipocytes caused significantly higher cholesterol esters, activation of the transcription factor sterol regulatory element-binding protein-1 (SREBP-1), and a shift in macrophage polarity from M2 to M1 macrophages. We found that the loss of adipocyte PPARα caused significantly higher expression of the Per-Arnt-Sim kinase (PASK), a kinase that activates SREBP-1. The hyperactivity of the PASKâSREBP-1 axis significantly increased the lipogenesis proteins fatty acid synthase (FAS) and stearoyl-Coenzyme A desaturase 1 (SCD1) and raised the expression of genes for cholesterol metabolism (Scarb1, Abcg1, and Abca1). The loss of adipocyte PPARα increased Nos2 in the males, an M1 macrophage marker indicating that the population of macrophages had changed to proinflammatory. Our results demonstrate the first adipose-specific actions for PPARα in protecting against lipogenesis, inflammation, and cholesterol ester accumulation that leads to adipocyte tissue expansion in obesity
Sorption of Ochratoxin A from Aqueous Solutions Using ÎČ-Cyclodextrin-Polyurethane Polymer
The ability of a cyclodextrin-polyurethane polymer to remove ochratoxin A from aqueous solutions was examined by batch rebinding assays. The results from the aqueous binding studies were fit to two parameter models to gain insight into the interaction of ochratoxin A with the nanosponge material. The ochratoxin A sorption data fit well to the heterogeneous Freundlich isotherm model. The polymer was less effective at binding ochratoxin A in high pH buffer (9.5) under conditions where ochratoxin A exists predominantly in the dianionic state. Batch rebinding assays in red wine indicate the polymer is able to remove significant levels of ochratoxin A from spiked solutions between 1â10 ÎŒg·Lâ1. These results suggest cyclodextrin nanosponge materials are suitable to reduce levels of ochratoxin A from spiked aqueous solutions and red wine samples
Determination of the LOQ in real-time PCR by receiver operating characteristic curve analysis: application to qPCR assays for Fusarium verticillioides and F. proliferatum
Real-time PCR (qPCR) is the principal technique for the quantification of pathogen biomass in host tissue, yet no generic methods exist for the determination of the limit of quantification (LOQ) and the limit of detection (LOD) in qPCR. We suggest using the Youden index in the context of the receiver operating characteristic (ROC) curve analysis for this purpose. The LOQ was defined as the amount of target DNA that maximizes the sum of sensitivity and specificity. The LOD was defined as the lowest amount of target DNA that was amplified with a false-negative rate below a given threshold. We applied this concept to qPCR assays for Fusarium verticillioides and Fusarium proliferatum DNA in maize kernels. Spiked matrix and field samples characterized by melting curve analysis of PCR products were used as the source of true positives and true negatives. On the basis of the analysis of sensitivity and specificity of the assays, we estimated the LOQ values as 0.11Â pg of DNA for spiked matrix and 0.62Â pg of DNA for field samples for F. verticillioides. The LOQ values for F. proliferatum were 0.03Â pg for spiked matrix and 0.24Â pg for field samples. The mean LOQ values correspond to approximately eight genomes for F. verticillioides and three genomes for F. proliferatum. We demonstrated that the ROC analysis concept, developed for qualitative diagnostics, can be used for the determination of performance parameters of quantitative PCR
Les mycotoxines dans les aliments des ruminants, leur devenir et leurs effets chez l'animal
National audienceMycotoxins are secondary metabolites produced by moulds belonging chiefly to the Aspergillus, Penicillium and Fusarium genera. They are found on a large variety of food and feeds before, during and after harvest, Because of their individual and synergetic toxicity, the diversity of mycotoxins is risky for consumers of contaminated food. The metabolism of mycotoxins is complex in ruminants. It includes several pathways of bio-activation and detoxification which are controlled by the action of enzymes from the digestive microbial ecosystem and from the host. Part of the toxins or their metabolites can be transferred to the biological tissues. Most of them are eliminated in the urine, faeces and milk. Differences in sensitivity to the toxins have been observed for different animal species. For ruminants, toxicity generally appears through minor chronic troubles and rarely leads to death. A decrease in feed intake and the associated performances is generally observed. A possible presence of residues in edible animal products (milk, meat, offal) has to be considered. Food safety is associated to a severe control of fungal contamination of plants through the techniques of culture, harvest, preservation, by elimination of contaminated feeds, and by the decrease of toxin bio-availability in the digestive tract by means of binders or adsorbents.Les mycotoxines sont des mĂ©tabolites secondaires sĂ©crĂ©tĂ©s par des moisissures appartenant principalement aux genres Aspergillus, Penicillium et Fusarium. Elles sont produites sur une large variĂ©tĂ© de denrĂ©es alimentaires avant, pendant et aprĂšs rĂ©colte. En raison de la diversitĂ© de leurs effets toxiques et de leurs propriĂ©tĂ©s synergiques, les mycotoxines prĂ©sentent un risque pour le consommateur dâaliments contaminĂ©s. Le mĂ©tabolisme des mycotoxines est complexe et comprend plusieurs voies de bioactivation et de dĂ©toxication rĂ©gies par des mĂ©canismes de biotransformation rĂ©sultant de lâaction dâenzymes de lâhĂŽte et de la flore microbienne prĂ©sente dans le tube digestif. Une partie des toxines ou de leurs mĂ©tabolites peut se fixer dans les tissus biologiques ; la majoritĂ© est Ă©liminĂ©e par voie urinaire, fĂ©cale et lactĂ©e. Des diffĂ©rences de sensibilitĂ© sont observĂ©es entre espĂšces animales. Chez les ruminants, la toxicitĂ© se manifeste gĂ©nĂ©ralement par des troubles chroniques lĂ©gers et nâaboutit que rarement Ă la mort. Une diminution de lâingestion et des performances zootechniques est gĂ©nĂ©ralement observĂ©e. Le problĂšme de la prĂ©sence Ă©ventuelle de rĂ©sidus toxiques se pose pour les produits animaux destinĂ©s Ă la consommation humaine (lait, viande, abats). La rĂ©duction des risques passe par un contrĂŽle de la contamination fongique des vĂ©gĂ©taux rĂ©sultant de la maĂźtrise des mĂ©thodes de culture, de rĂ©colte et de conservation, par des techniques dâĂ©limination des toxines sur lâaliment contaminĂ©, et par une rĂ©duction de leur biodisponibilitĂ© dans le tractus digestif des animaux par lâemploi dâadsorbants
Mycotoxins in feeds and their fate in animals : A review
Mycotoxins are secondary metabolites secreted by moulds, mostly belonging
to the three genera Aspergillus, Penicillium and Fusarium. They are produced
in cereal grains as well as forages before, during and after harvest, in various
environmental conditions. Due to the diversity of their toxic effects and their
synergetic properties, mycotoxins are considered as risky to the consumers
of contaminated foods. Mycotoxin metabolism is complex and involves pathways
of bioactivation and detoxification in both humans and animals. Detoxification occurs
via biotransformation mediated by enzymes in the host cells and in the digestive
microbial flora. Some of the toxins or their metabolites may become fixed in animal
or human tissues. However, most are eliminated in the urine, faeces and milk. In animals,
toxicity is generally revealed as chronic minor troubles and only rarely causes death.
The presence of mycotoxins in feeds may decrease feed intake and affect animal performance.
In addition, the possible presence of toxic residues in edible animal products (milk,
meat, offal), may have some detrimental effects on human health. Maximum acceptable
doses in feeds and milk have been set for certain mycotoxins by international authorities.
The potential risks of mycotoxins may be controlled by checking plant material for fungal
contamination, by improving methods of cultivation, harvest and storage, by eliminating
or diluting toxins from the contaminated food or feeds, and by using adsorbents to reduce
the bioavailability of toxins in the digestive tracts of animals. These measures will be
assessed in the present paper.Les mycotoxines dans les aliments et leur devenir chez le ruminant. Les mycotoxines
sont des métabolites secondaires produits par les moisissures appartenant principalement
aux genres Aspergillus, Penicillium et Fusarium. Ces moisissures se développent
sur les grains des céréales et dans les fourrages pendant la culture au champ, pendant
la récolte et durant la période de conservation. Les mycotoxines sont souvent présentes
en mélange et constituent un risque pour les consommateurs en raison de leur synergie.
Le métabolisme des mycotoxines est complexe. Il implique chez l'homme et les animaux,
des voies de bioactivation et de détoxication. La détoxication fait appel à des processus
de biotransformation impliquant des enzymes de l'hĂŽte et de l'Ă©cosystĂšme microbien
présent dans le tube digestif. Certaines des toxines ou de leurs métabolites peuvent
ĂȘtre fixĂ©s dans les tissus animaux ou humains. Cependant, la majoritĂ© est Ă©liminĂ©e
dans l'urine, dans les fÚces et dans le lait. La toxicité se manifeste généralement
sous forme de troubles chroniques difficiles Ă identifier, et rarement par la mort
de l'animal. La présence de mycotoxines dans les aliments diminue la plupart du temps
les quantités d'aliments ingérés ainsi que les performances zootechniques des animaux.
La présence de résidus toxiques dans les produits animaux destinés à la consommation
humaine (lait, viande, abats) constitue un risque potentiel qu'il est nécessaire
d'évaluer pour mieux répondre à la demande sociétale de sécurité dans la chaßne alimentaire.
Des doses acceptables devront ĂȘtre dĂ©finies pour les toxines les plus dangereuses.
En parallĂšle, des moyens de contrĂŽle devront ĂȘtre mis en place pour vĂ©rifier l'innocuitĂ©
des produits alimentaires mis sur le marché. Le risque potentiel des mycotoxines peut
ĂȘtre diminuĂ© en Ă©vitant la contamination des plantes par les moisissures au moment de
leur culture, de leur récolte et de leur conservation. Il est également possible de
réduire la concentration en toxines des plantes contaminées par dilution avec des
aliments sains et par des traitements appropriés, et (ou) de limiter la biodisponibilité
des mycotoxines par l'ajout de ligands spécifiques. Ces différents aspects seront traités
dans le présent article
Comparison of the sequestering properties of yeast cell wall extract and hydrated sodium calcium aluminosilicate in three in vitro
How yeast cell wall components can alleviate mycotoxicosis in animal production and improve the safety of edible animal products
International audienceSeveral authors have reported that the addition of yeast cell walls to contaminated feeds alleviates the harmful effects of mycotoxins, but nothing is known on the chemical interactions between the binder and the toxins. We showed that beta-D-glucans are the yeast component responsible for the complexation of mycotoxins, and that the reticular organization of beta-D-glucans and the distribution between beta-(1,3)-D-glucans and beta-(1,6)-D-glucans play a major role in the efficacy. Weak hydrogen and van der Waals bonds are involved in the complexation of mycotoxins by beta-D-glucans, thus indicating that the chemical interaction is more of "adsorption type" than "binding type". We performed molecular modelling and calculated potential energy to estimate the stability of the complexes
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