Poloxamer 407/188 Binary Thermosensitive Gel as a Moxidectin Delivery System: In Vitro Release and In Vivo Evaluation.

Moxidectin (MXD) is an antiparasitic drug used extensively in veterinary clinics. In this study, to develop a new formulation of MXD, a thermosensitive gel of MXD (MXD-TG) was prepared based on poloxamer 407/188. Furthermore, the gelation temperature, the stability, in vitro release kinetics and in vivo pharmacokinetics of MXD-TG were evaluated. The results showed that the gelation temperature was approximately 27 °C. MXD-TG was physically stable and can be released continuously for more than 96 h in vitro. The Korsmeyer−Peppas model provided the best fit to the release kinetics, and the release mechanism followed a diffusive erosion style. MXD-TG was released persistently for over 70 days in sheep. Part of pharmacokinetic parameters had a difference in female and male sheep (p < 0.05). It was concluded that MXD-TG had a good stability, and its release followed the characteristics of a diffusive erosion style in vitro and a sustained release pattern in vivo.

In vitro antibiofilm activity of resveratrol against avian pathogenic Escherichia coli.

BACKGROUND: Avian pathogenic Escherichia coli (APEC) strains cause infectious diseases in poultry. Resveratrol is extracted from Polygonum cuspidatum, Cassia tora Linn and Vitis vinifera, and displays good antimicrobial activity. The present study aimed to investigate the antibiofilm effect of resveratrol on APEC in vitro. The minimum inhibitory concentration (MIC) of resveratrol and the antibiotic florfenicol toward APEC were detected using the broth microdilution method. Then, the effect of resveratrol on swimming and swarming motility was investigated using a semisolid medium culture method. Subsequently, the minimum biofilm inhibitory concentration (MBIC) and the biofilm eradication rate were evaluated using crystal violet staining. Finally, the antibiofilm activity of resveratrol was observed using scanning electron microscopy (SEM). Meanwhile, the effects of florfenicol combined with resveratrol against biofilm formation by APEC were evaluated using optical microscopy (OM) and a confocal laser scanning microscopy (CLSM). RESULTS: The MICs of resveratrol and florfenicol toward APEC were 128 µg/mL and 64 µg/mL, respectively. The swimming and swarming motility abilities of APEC were inhibited in a resveratrol dose-dependent manner. Furthermore, resveratrol showed a significant inhibitory activity against APEC biofilm formation at concentrations above 1 µg/mL (p < 0.01). Meanwhile, the inhibitory effect of resveratrol at 32 µg/mL on biofilm formation was observed using SEM. The APEC biofilm was eradicated at 32 µg/mL of resveratrol combined with 64 µg/mL of florfenicol, which was observed using CLSM and OM. Florfenicol had a slight eradication effect of biofilm formation, whereas resveratrol had a strong biofilm eradication effect toward APEC. CONCLUSION: Resveratrol displayed good antibiofilm activity against APEC in vitro, including inhibition of swimming and swarming motility, biofilm formation, and could eradicate the biofilm.

Transcriptome profile analysis reveals cardiotoxicity of maduramicin in primary chicken myocardial cells.

Maduramicin, an excellent ionophore antibiotic, is extensively used to control coccidiosis in poultry. Numerous maduramicin intoxications have been reported in farm animal and human due to its relatively narrow safety range, with necrosis or degeneration of cardiac and skeletal muscles as hallmark. To date, the mechanisms of maduramicin-induced cardiotoxicity remain unclear in chicken and other animals. Maduramicin (5 µg/mL)-treated primary chicken myocardial cells were used for RNA sequencing (RNA-Seq) and bioinformatics analysis in this study. A total of 1442 differential expressed genes were identified. 810 genes were up-regulated and the rest 632 genes were down-regulated. Transcriptome analysis revealed that the cytokine-cytokine receptor interaction, apoptosis, calcium signal and cytoplasmic vacuolization pathways were significantly affected. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that gene expression patterns were consistent with RNA-Seq analysis. Pro-inflammatory cytokines including tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8), apoptosis ratios, cleaved caspase-3, intracellular calcium level and Ca2+-ATPase activity were elevated after maduramicin (0.05, 0.5 and 5 µg/mL) treatment. Massive vacuole formation was found in the cytoplasm by morphology and transmission electron microscopy observation. Taken together, the results suggested that maduramicin exerted its cardiotoxicity by multiple molecular mechanisms in primary chicken myocardial cells.

Baicalein inhibits biofilm formation of avian pathogenic Escherichia coli in vitro mainly by affecting adhesion.

Avian pathogenic Escherichia coli (APEC) is a widespread bacterium that causes significant economic losses to the poultry industry. APEC biofilm formation may result in chronic, persistent, and recurrent infections in clinics, making treatment challenging. Baicalein is a natural product that exhibits antimicrobial and antibiofilm activities. This study investigates the inhibitory effect of baicalein on APEC biofilm formation at different stages. The minimum inhibitory concentration (MIC) of baicalein on APEC was determined, and the growth curve of APEC biofilm formation was determined. The effects of baicalein on APEC biofilm adhesion, accumulation, and maturation were observed using optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy. The biofilm inhibition rate of baicalein was calculated at different stages. The MIC of baicalein against APEC was 256 µg/mL. The process of APEC biofilm maturation takes approximately 48 h after incubation, with initial adhesion completed at 12 h, and cell accumulation finished at 24 h. Baicalein had a significant inhibitory effect on APEC biofilm formation at concentrations above 1 µg/mL (p < 0.01). Notably, baicalein had the highest rate of biofilm formation inhibition when added at the adhesion stage. Therefore, it can be concluded that baicalein is a potent inhibitor of APEC biofilm formation in vitro and acts, primarily by inhibiting cell adhesion. These findings suggests that baicalein has a potential application for inhibiting APEC biofilm formation and provides a novel approach for the prevention and control APEC-related diseases.

Effect of resveratrol on the biofilm formation and physiological properties of avian pathogenic Escherichia coli.

Avian pathogenic Escherichia coli (APEC) is widely distributed, causing great economic losses to the poultry industry. The formation of APEC biofilms causes chronic, persistent, and repeated infections in the clinic, making treatment difficult. Resveratrol is a natural product, which has good health benefits including antimicrobial, anti-inflammatory, and cardiovascular activities. Resveratrol shows efficient inhibition of bacterial biofilm formation. However, a comprehensive understanding of the proteomic properties of APEC treated resveratrol is still lacking. In this study, APEC cells treated by resveratrol were investigated using a label-free differential proteomic method. Several proteins, including those related to a two-component system and chemotaxis, were found to be implicated in APEC biofilm formation. In addition, the physiological properties were significantly changed in terms of purine, pyruvate, and glyoxylate and dicarboxylate metabolism in APEC. Data are available via ProteomeXchange with the identifier PXD025706. We speculated that pyruvate dehydrogenase might be a potential target to inhibit Escherichia coli biofilm formation. Overall, our results indicated that resveratrol inhibits APEC biofilm formation by regulating the levels of proteins in two-component systems, especially chemotaxis proteins. The results showed that resveratrol had a potential application in inhibiting the biofilm formation of APEC. SIGNIFICANCE: This study elucidated the mechanism of resveratrol inhibiting biofilm formation of avian pathogenic Escherichia coli (APEC) based on a label-free differential proteomics. It was indicated that resveratrol inhibits APEC biofilm formation by regulating the levels of proteins in two component systems, especially chemotaxis proteins. Meanwhile, we speculated that pyruvate dehydrogenase might be a potential target to inhibit Escherichia coli biofilm formation. It shows that resveratrol has a potential application prospect in inhibiting the biofilm formation of APEC.

Maduramicin triggers methuosis-like cell death in primary chicken myocardial cells.

Maduramicin frequently induces severe cardiotoxicity in broiler chickens as well as in humans who consume maduramicin accidentally. Apoptosis and non-apoptotic cell death occur concurrently in the process of maduramicin-induced cardiotoxicity; however, the underlying mechanism of non-apoptotic cell death is largely unknown. Here, we report the relationship between maduramicin-caused cytoplasmic vacuolization and methuosis-like cell death as well as the underlying mechanism in primary chicken myocardial cells. Maduramicin induced a significant increase of cytoplasmic vacuoles with a degree of cell specificity in primary chicken embryo fibroblasts and chicken hepatoma cells (LMH), along with a decrease of ATP and an increase of LDH. The accumulated vacuoles were partly derived from cellular endocytosis rather than the swelling of endoplasm reticulum, lysosomes, and mitochondria. Moreover, the broad-spectrum caspase inhibitor carbobenzoxy-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk) did not prevent maduramicin-induced cytoplasmic vacuolization. DNA ladder and cleavage of PARP were not observed in chicken myocardial cells during maduramicin exposure. Pretreatment with 3-methyladenine (3-MA) and cholorquine (CQ) of chicken myocardial cells did not attenuate cytoplasmic vacuolization and cytotoxicity, although LC3 and p62 were activated. Bafilomycin A1 almost completely prevented the generation of cytoplasmic vacuoles and significantly attenuated cytotoxicity induced by maduramicin, along with downregulation of K-Ras and upregulation of Rac1. Taken together, "methuosis" due to excessive cytoplasmic vacuolization mediates the cardiotoxicity of maduramicin. This provides new insights for understanding a nonclassical form of cell death in the field of drug-induced cytotoxicity.

Preparation and in vitro release kinetics of ivermectin sustained-release bolus optimized by response surface methodology.

Sustained-release formulations of ivermectin (IVM) are useful for controlling parasitic diseases in animals. In this work, an IVM bolus made from microcrystalline cellulose (MCC), starch and low-substituted hydroxypropyl cellulose (LS-HPC) was optimized by response surface methodology. The bolus was dissolved in a cup containing 900 mL of dissolution medium at 39.5 °C, under with stirring at 100 rpm. A quadratic model was formulated using analysis of variance according to the dissolution time. The optimized formulation of the bolus contained 8% MCC, 0.5% starch, and 0.25% LS-HPC. The length, width, and height of the prepared IVM bolus were 28.12 ± 0.14, 16.1 ± 0.13, and 13.03 ± 0.05 mm, respectively. The bolus weighed 11.4842 ± 0.1675 g (with a density of 1.95 g/cm3) and contained 458.26 ± 6.68 mg of IVM. It exhibited in vitro sustained-release for over 60 days, with a cumulative amount and percentage of released IVM of 423.72 ± 5.48 mg and 92.52 ± 1.20%, respectively. The Korsmeyer-Peppas model provided the best fit to the dissolution release kinetics, exhibiting an R2 value close to 1 and the lowest Akaike Information Criterion among different models. The parameter n (0.5180) of the Korsmeyer-Peppas model was between 0.45 and 0.89. It was demonstrated that the release mechanism of the IVM bolus followed a diffusive erosion style.

Salinomycin induces primary chicken cardiomyocytes death via mitochondria mediated apoptosis.

Salinomycin, as a polyether ionophore antibiotic, is extensively used as a feed additive against coccidiosis in poultry and as a growth promoter of ruminants worldwide. Owing to its narrow therapeutic index, numerous intoxication have been reported in target/non-target animals by overdosage, misuse or drug interactions as well as human who consumed salinomycin accidently. Salinomycin-induced cardiotoxicity in chicken and non-target animals is considered as a major contributor to animal death. In the current study, we aim to elucidate the underlying mechanism of its myocardial toxicity using primary chicken myocardial cell as an in vitro model. The results showed that salinomycin altered cellular morphology and induced cell death in a concentration-dependent manner. Salinomycin treatment elevated the permeability of the cell membrane and leaded to the efflux of enzymes, including creatine kinase (CK) and lactate dehydrogenase (LDH). Flow cytometry analysis indicated the number of apoptotic cells increased significantly by salinomycin exposure. Furthermore, caspase-3 and caspase-9 were activated at gene and protein level rather than caspase-8, along with the up-regulation of apoptosis genes Bax, Cytochrome C, Apoptotic peptidase activating factor 1 (Apaf-1) and the down-regulation of Bcl-2. Salinomycin-induced mitochondrial dysfunction was accompanied by the significant decrease of mitochondrial membrane potential (MMP) and the severe ultrastructure damage. In conclusion, these findings suggest that the toxic dose of salinomycin induces severe cardiomyocytes death through mitochondria mediated apoptosis pathway.

Maduramicin induces apoptosis in chicken myocardial cells via intrinsic and extrinsic pathways.

Maduramicin is one of the most extensively used anticoccidial drugs for the treatment of Eimeria spp. infections. However, overdosage, misuse and drug interactions have resulted in the development of ionophore toxic syndrome. Heart and skeletal muscles have been identified as the main target organs of toxicity. In the present study, primary chicken myocardial cells were isolated to investigate the toxicity and underlying mechanisms of maduramicin. Our results showed that maduramicin causes morphological changes and a decrease in the viability of chicken myocardial cells. Annexin V-FITC/PI and 4',6-diamidino-2-phenylindole (DAPI) staining showed a significant increase in the number of apoptotic cells. Furthermore, caspases-3/8/9 were activated at the gene and protein levels and this was accompanied by the upregulation of apoptosis-related genes, including bcl-2, bax, and cytochrome C. Treatment with the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp (O-Me) fluoromethyl ketone (z-VAD-fmk) ameliorated the apoptosis and cytotoxicity. Furthermore, intracellular Ca2+ and reactive oxygen species (ROS) were elevated, whereas mitochondrial membrane potential (MMP) and intracellular glutathione (GSH) decreased with exposure to maduramicin. The antioxidant N-acetyl-cysteine (NAC) had no significant effect on maduramicin-induced cytotoxicity and apoptosis. Taken together, our findings demonstrate that maduramicin is cytotoxic to primary chicken myocardial cells via caspase dependent and independent apoptotic pathways.

Prevalence of Eimeria species in domestic chickens in Anhui province, China.

Prevalence studies can adequately assist in the design of prophylaxis strategies for disease control. Here, the prevalence of Eimeria species in chickens was investigated in Anhui province, China, from July to September 2016. A total of 171 samples were tested by microscopic examination and molecular methods. The prevalence of coccidiosis in Anhui province was found to be 87.75% (150/171). Eimeria tenella was the most prevalent species (80.67%, 121/150), and Eimeria necatrix, Eimeria mitis, Eimeria maxima, Eimeria brunetti and Eimeria acervulina were 68% (102/150), 55.33% (83/150), 54.67% (82/150), 44.67% (67/150) and 2.67% (4/150), respectively. Eimeria praecox was not detected at all. The most common combinations are E. tenella, E. maxima, E. necatrix, E. brunetti and E. mitis (26.67%, 40/150), followed by E. tenella, E. maxima and E. necatrix (19.33%, 29/150). Eimeria necatrix exhibited the highest participation in multiple infections. The results of the present study suggested that Eimeria infection is mixed, severe and widespread in chickens, Therefore, integrated strategies should be performed to prevent and control coccidial infection in chickens in Anhui province.

[Effects of Huangqi on phagocytic activity of peritoneal macrophage of mice].

OBJECTIVE: To study the effects of Huangqi decoction (HQD) on phagocytic activity of peritoneal macrophage of mice. METHOD: One hundred Kunming mice, whose weight varied from 18 g to 22 g, were selected and divided into 10 groups randomly in eluding contrast group, groups conducted at different doses of HQD by ig, groups conducted in various ways of taking medicine, and groups conducted with comparative treat combining Huangqi and Dexamethasone. Mice in every group were taken medicine one time daily for 6 days. RESULT: Among the groups treated at different doses of HQD, phagocytic rate and phagocytic index of mice, which were taken HQD by ig at high, middle, and low doses, were significantly higher (P < 0.01) than that of mice in contrast group, at the same time the effect in group with high dose was the best. Among the groups treated in various ways of taking medicine, phagocytic rate of the ip group was significantly better (P < 0.01) than that of the sc group and that of the ig group respectively, but there was not significant difference (P > 0.05) of phagocytic index among them. Among the groups combining Huangqi and Dexamethasone, Huangqi could antagonize the immunosuppressive effect of Dexamethasone obviously (P < 0.01). CONCLUSION: HQD at different doses and with various ways of taking medicine could improve phagocytic activity of peritoneal macrophage of mice at different degree, and could antagonize the immunosuppressive effect of Dexamethasone.

Prevalence and characteristics of extended-spectrum ß-lactamase and plasmid-mediated fluoroquinolone resistance genes in Escherichia coli isolated from chickens in Anhui province, China.

The aim of this study was to characterize the prevalence of extended-spectrum ß-lactamase (ESBL) genes and plasmid-mediated fluoroquinolone resistance (PMQR) determinants in 202 Escherichia coli isolates from chickens in Anhui Province, China, and to determine whether ESBL and PMQR genes co-localized in the isolates. Antimicrobial susceptibility for 12 antimicrobials was determined by broth microdilution. Polymerase chain reactions (PCRs), DNA sequencing, and pulsed field gel electrophoresis (PFGE) were employed to characterize the molecular basis for ß-lactam and fluoroquinolone resistance. High rates of antimicrobial resistance were observed, 147 out of the 202 (72.8%) isolates were resistant to at least 6 antimicrobial agents and 28 (13.9%) of the isolates were resistant to at least 10 antimicrobials. The prevalence of blaCTX-M, blaTEM-1 and blaTEM-206 genes was 19.8%, 24.3% and 11.9%, respectively. Seventy-five out of the 202 (37.1%) isolates possessed a plasmid-mediated quinolone resistance determinant in the form of qnrS (n = 21); this determinant occurred occasionally in combination with aac(6')-1b-cr (n = 65). Coexistence of ESBL and/or PMQR genes was identified in 31 of the isolates. Two E. coli isolates carried blaTEM-1, blaCTX-M and qnrS, while two others carried blaCTX-M, qnrS and aac(6')-1b-cr. In addition, blaTEM-1, qnrS and aac(6')-1b-cr were co-located in two other E. coli isolates. PFGE analysis showed that these isolates were not clonally related and were genetically diverse. To the best of our knowledge, this study is the first to describe detection of TEM-206-producing E. coli in farmed chickens, and the presence of blaTEM-206, qnrS and aac(6')-1b-cr in one of the isolates.