The cystine/glutamate exchanger (xCT, SLC7A11) is a component of the system Xc amino-acid antiporter that is able to export glutamate and import cysteine into cells. The xCT amino acid exchanger has ...received a lot of attention, due to the fact that cysteine is an essential substrate for the synthesis of glutathione (GSH), an endogenous antioxidant in cells. The objective of this research was to clone the full-length cDNA of chicken xCT, and to investigate the gene expression of xCT in different tissues, including intestinal segments of broiler chickens during development. The full-length cDNA of chicken xCT (2,703 bp) was obtained from the jejunum by reverse transcription-PCR and sequenced. Homology tests showed that chicken xCT had 80.4%, 80.2%, and 71.2% homology at the nucleotide level with humans, cattle, and rats, respectively. Likewise, amino acid sequence analysis showed that chicken xCT protein is 86.4%, 79.3%, and 75.6% homologous with humans, cattle, and rats, respectively. Additionally, phylogenetic analysis indicated that chicken xCT genes share a closer genetic relationship with humans and cattle, than with rats. The chicken xCT protein has 12 transmembrane helixes, 6 extracellular loops, and 5 intracellular loops. The mRNA of xCT was detected in all tissues, including intestinal segments, in which the mRNA expression of xCT was significantly higher (P < 0.05) within the colon, compared to the jejunum and ileum. During development, a linear pattern of changes regarding the levels of the xCT mRNA was found, indicating that there was an abundance of xCT within the duodenum (P < 0.05). Furthermore, there were changes of the xCT mRNA abundance in the colon during development, which displayed linear and cubic patterns (P < 0.05). These results indicated that xCT is widely expressed both in intestinal segments, as well as other organs that are not associated with nutrient absorption. Further investigation is needed to characterize the functional relevance of xCT activity in oxidative stress and inflammation in the small intestine of broiler chickens.
Bacterial quorum sensing (QS) is a cell-to-cell communication in which specific signals are activated to coordinate pathogenic behaviors and help bacteria acclimatize to the disadvantages. The QS ...signals in the bacteria mainly consist of acyl-homoserine lactone, autoinducing peptide, and autoinducer-2. QS signaling activation and biofilm formation lead to the antimicrobial resistance of the pathogens, thus increasing the therapy difficulty of bacterial diseases. Anti-QS agents can abolish the QS signaling and prevent the biofilm formation, therefore reducing bacterial virulence without causing drug-resistant to the pathogens, suggesting that anti-QS agents are potential alternatives for antibiotics. This review focuses on the anti-QS agents and their mediated signals in the pathogens and conveys the potential of QS targeted therapy for bacterial diseases.
Egg has ben documented as a rich source for the supply of biologically active peptides. This study characterizes the immunomodulatory effects of an egg white enzymatic hydrolysate (EWH) using a ...BALB/c mouse model of egg allergy. Mice were orally sensitized to egg white and subsequently gavaged with EWH. ELISA results indicated significant reductions of both serum histamine and specific IgE titers in EWH-fed mice, accompanied by a repression of both IL-4 and IFN-γ production in spleen cell cultures. Similarly, real-time RT-PCR analyses highlighted decreased mRNA expression of IFN-γ and IL-12 (Th1-biased), as well as lower ratios of IL-4 and IL-13 mRNA (Th2-biased). On the other hand, increased intestinal expressions of TGF-β and FOXp3 mRNA were determined in EWH-fed mice, suggesting induction of local regulatory mechanisms. The presence of immunodominant epitopes was proposed to be responsible for the immunomodulatory effects observed.
ABSTRACT Background: Nutritional prebiotic supplementation represents an attractive approach for interventions of allergy. In this study, the potential therapeutic effect of β-1, 4 mannobiose (MNB) ...in a murine model of cedar pollinosis was investigated. Methods: Groups of Balb/c mice were intranasally sensitized to Japanese cedar pollen extract, and subsequently administered with low or high dose MNB. Both intraperitoneal and intranasal challenges were performed to monitor for clinical signs. Frequency of sneezing was recorded. Serum, spleen and Peyer's patches were collected for various biomarker analyses. Anti-allergic activity of MNB using RBL-2H3 cells was also evaluated. Results: Significant decrease in sneezing frequency, histamine, interleukin (IL)-4 and IL-17A and increase in TGF-β and IL-10 concentration were exhibited by the MNB-treated mice, However, Cry j1 and Cry j2-specific IgE activity remained unaltered. The high dose MNB treatment increased total IgA activity and IL-10, TGF-β and FoxP3 and decreased IL-4, IL-17A, and RORγT mRNA expression. Inhibition of activation of RBL-2H3 cells was observed via decrease in histamine, intracellular Ca2+ concentration, and FcεRI mRNA expression. Conclusions: We demonstrated the immunomodulatory effects of MNB and conclude that MNB is a potential therapeutic molecular nutritional supplement candidate for treatment of pollen allergy.
Dietary supplementation with unique prebiotic nondigestible carbohydrates has been shown to suppress allergy. In the present study, the prophylactic efficacy of a disaccharide β-1, 4 mannobiose (MNB) ...in a BALB/C mouse model of intranasally-induced pollen allergy was characterized.
Balb/c mice were pretreated with MNB orally and sensitized with pollen extract intraperitoneally and intranasally and challenged with histamine and crude pollen extract. Outcomes were measured as clinical signs, antibody isotypes, cytokine gene and protein expression patterns.
The MNB-treated mice had lower sneezing frequency as compared to the positive control mice (P < 0.05). The low dose MNB-treated mice had less histamine (P < 0.05). However, the Cry j1 and Cry j 2-specific IgE, IgG, IgG1 and IgG2a antibody activity did not differ between groups (P > 0.05). The MNB-treated mice had increased IFN-γ (P < 0.05), and decreased IL-4 (P < 0.05). Mice in the high dose group had increased IL-10 (P < 0.05). However, TGF-β and IL-17 concentration did not differ between groups (P > 0.05). Both total and Cry j1 and Cry j 2-specific IgA were increased in the high dose group. Real-time RT-PCR analysis indicated that IL-4 and IL-17 mRNA expression were lower in MNB-treated mice (P < 0.05).
This work provides insights into using MNB as a potential prebiotic immunomodulator via decreased clinical signs, improved type1/type 2 balance, and IgA production, thus validating the potential use of MNB as a prophylactic prebiotic candidate to attenuate allergic response.
The anti-allergic immunomodulatory effects of Quillaja saponin in antigen-stimulated rat basophilic leukemia cell line RBL-2H3 were investigated. Quillaja saponin exhibited a significant inhibitory ...activity using β-hexosaminidase and histamine release assays on anti-DNP-IgE-sensitized rat basophilic leukemia (RBL)-2H3 cells in a dose-dependent manner when tested in the range of 0.5–8.0 μg/mL. In addition, Quillaja saponin also suppressed mRNA expression of interleukins (IL)-4 and IL-6. In order to explore the antigen-allergy mechanisms of Quillaja saponin in mast cells, intracellular Ca2+ level and IgE receptor FcεRI mRNA expression were also determined. It was found that the intracellular Ca2+ level was also decreased with Quillaja saponin tested at various concentrations. Furthermore, real time-PCR results showed that mRNA expression of FcεRI α chain was significantly suppressed by Quillaja saponin, and not of the β and γ chains.
Abstract
Post-weaning diarrhea in piglets, caused primarily by enterotoxigenic Escherichia coli is a major cause of productive and economic losses to the swine industry. Traditionally, the swine ...industry has managed this disease by utilizing starter diets containing highly digestible and specialized ingredients such as spray-dried porcine plasma and sub-therapeutic levels of antibiotics as growth promoters. However, there has intense public pressure to discontinue the use of animal products and antibiotics in pig diets for fear that these products represent a risk to human health. This has sparked great interest in swine nutrition is to identify effective, safe, and environmentally friendly nutritional interventions that could be used in place of in-feed antibiotics. This requires that any such intervention is rigorously tested under conditions that represent those that are encountered in production settings. To this end, the Escherichia coli K88 (or F4) disease challenge model has been used to test the potential of these interventions to support gut health and function in piglets and to allow investigations into the mode of action underlying any such effects. Although this model has been applied successfully to examine the efficacy of different nutritional interventions, including diet formulation strategies and addition of various feed additives, the degree of success achieved varies due to among other factors such as dose used, age of the pigs, and study duration. Being a disease challenge model, animal care oversight, regulatory requirements for Containment Level II facilities, and trial site managements to avoid cross-contamination among treatment groups add to the complexity of protocols for running trials involving this model. Nonetheless, the enterotoxigenic Escherichia coli model has been an effective tool in our hands to test the efficacy of various nutritional interventions in protecting piglets against post-weaning diarrhea disease and to elucidate their modes of action.
The accurate estimation of mechanical parameters is essential for the control optimization and condition monitoring of permanent-magnet synchronous motor (PMSM) drives. In this article, an online ...parallel estimation scheme is proposed based on a network of three interconnected extended sliding-mode observers. With a two-step mechanism derived from the developed network, this scheme can simultaneously achieve the accurate real-time observation of three mechanical parameters, including the viscous friction coefficient, the moment of inertia, and the load torque. The first step utilizes the presented network to precisely acquire the Coulomb friction coefficient by offering only one speed. With aiding from this estimated coefficient, the second step attains the high-precision online identification of the three concerned parameters by compensating the Coulomb friction torque to counteract its adverse effect. These two steps are implemented utilizing the identical network, thus, furthest avoiding increasing the estimation complexity. Besides, any additional knowledge other than the rotor speed and electromagnetic torque is no longer required for guaranteeing the asymptotic convergence of the estimation errors. Sufficient evaluations from simulations and experiments confirm the validity of the proposed scheme.
Acquiring the accurate knowledge of nonlinear friction and load torque is of great interest for optimizing the control behavior of permanent-magnet synchronous motor drives. In this work, a ...friction-and-load adaptive identification scheme based on a parallel-observer-based network with model compensation (POBN-MC) is presented. The developed network possesses a parallel structure consisting of the designed two novel observers, which involve a gain-adaptation super-twisting load torque observer and a variable-learning-rate Adaline inertia observer. A nonempirical friction model is proposed to capture friction, forming the model compensation part that is exploited for correcting the torque input of the network. With a two-step mechanism derived from the POBN-MC, the proposed scheme attains the online adaptive identification of the friction and load torque in a manner that integrates both accuracy and simplicity. In the first step, an explicit mapping relationship between the nonlinear friction torque and the rotor speed is determined with the speed response triggered by the natural deceleration. The second step accomplishes the online observation with regard to friction-and-load information matching the real-time operating conditions. Sufficient theoretical analyses, as well as the validations of numerous simulations and experiments, are presented to support the suggested scheme.
Abstract
The aim of this study was to investigate the effects of diet complexity and l-Thr supplementation level on the growth performance, immune response, intestinal barrier function, and microbial ...metabolites in nursery pigs. Thirty-two weaned pigs (body weight 7.23 ± 0.48 kg) were randomly assigned to dietary treatments in a 2 × 2 factorial arrangement based on diet complexity (complex or simple) and dietary Thr content. The complex diet contained fish meal, plasma protein, and dried whey to mimic a conventional nursery diet. The simple diet was formulated with corn, wheat, and soybean meal and did not contain any animal products. l-Thr was supplemented to each diet to supply either 100% (STD Thr) or 115% (SUP Thr) of the NRC (2012) requirement for standardized ileal digestible Thr. Pigs were individually housed and fed experimental diets ad libitum for 14 d. Diet complexity, dietary Thr content, and their interactions were considered the main effects. Pigs fed the simple diet had greater (P < 0.05) plasma interleukin (IL)-10 and IL-6 concentrations compared with those fed the complex diet on days 7 and 14, respectively. Simple diet-fed pigs tended to show greater (P < 0.10) expression of genes encoding for tumor necrosis factor-α, claudin-1, and zonula occludens-1 in the jejunum compared with complex diet-fed pigs. The simple diet-fed pigs had greater (P < 0.05) concentrations of NH3-N in the jejunum digesta than did complex diet-fed pigs. The SUP Thr increased (P < 0.05) villus height and goblet cell (GC) density in villi and crypts in the jejunum and deepened (P < 0.05) crypts in the proximal colon. The SUP Thr resulted in the upregulation (P < 0.05) of occludin gene expression and a tendency toward the downregulation (P = 0.10) of IL-6 gene expression in the jejunum. Interactions (P < 0.05) between diet complexity and l-Thr supplementation level were observed in GC density in the crypt, NH3-N concentration in the jejunum, and the contents of acetate, propionate, and total volatile fatty acids in the colon. In conclusion, feeding a simple diet to nursery pigs resulted in systemic and intestinal inflammation. The SUP Thr diet did not normalize the simple diet-induced inflammation but improved gut integrity. SUP Thr seems to have greater benefits with a simple diet than with a complex diet. Therefore, SUP Thr in a simple diet could be a beneficial nutritional strategy for enhancing gut health.
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