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The crystallization roller in thin strip continuous casting combines the cooling function of the plate crystallizer with the rolling function of the roll, thereby significantly enhancing process efficiency. This also imposes higher demands on the thermal conductivity and hardness of the crystallization roller. During the utilization of the crystallization roller, as it comes into contact with the billet, the base material must exhibit exceptional wear resistance. The thermal conductivity and mechanical properties of high-strength beryllium copper alloy C17200 and traditional crystallization material CrZrCu alloy C18150 were assessed at various temperatures using a laser thermal conductivity meter (LFA-427) and microhardness meter (ZD-HVZHT-10), respectively. Detailed analysis confirms the potential suitability of C17200 as an alternative material for crystallization rollers. The hardness of C17200 was twice that of C18150 while maintaining the original thermal conductivity. The wear characteristics of C17200 were investigated at room temperature (25 °C) and simulated operating conditions (300 °C) using a reciprocating wear tester (MZF-1). Additionally, the wear mechanism of C17200 at different temperatures was studied using scanning electron microscopy (SEM). The findings demonstrated that C17200 exhibited favorable wear resistance even at a temperature of 300 °C, thereby satisfying the performance criteria for the crystallization roller during operational usage.

Abstract Background Antimicrobial resistance is a threat to global public health and requires the development of new antibiotic alternatives to treat bacterial infection. Infection with Escherichia coli (E. coli) is the most common cause of diarrhea in pigs, especially in weaning piglets. The objective of this study was to characterize chemical properties of water-soluble extract (WSE) obtained from yeast cell wall, and study its antibacterial activity and antimicrobial mechanisms against E. coli. Results WSE was extracted from yeast cell wall by hot water, followed by anhydrous ethanol precipitation and deproteinization by Sevag method to obtain water-soluble polysaccharides (WSP, accounting for 76.53 ± 5.91% by weight of WSE). WSP was purified by DEAE-52 cellulose column and Sephadex G-100 column to obtain three fractions of polysaccharides, WSNP, WSAP-1 and WSAP-2. Physicochemical properties of them were then characterized. The average molecular weights of WSNP, WSAP-1 and WSAP-2 were 105,130, 94,581 and 91,247 Da, respectively. WSNP was composed of glucosamine (GlcN), glucose (Glc), mannose (Man) and glucuronic acid (GlcA) in a molar ratio of 8.6:55.2:34.4:1.8, WSAP-1 was consisted of GlcN, Glc and Man in a molar ratio of 10.9:42.2:46.9, and WSAP-2 was consisted of GlcN, galactose (Gal), Glc and Man in a molar ratio of 9.0:1.0:55.1:34.9. Spectral analysis indicated that all three polysaccharides had pyran polysaccharides, triple-helix structure, α- and β-glycosidic bond. The minimum inhibitory concentrations of WSE and WSP on E.coli were 25 mg/mL and 100 mg/mL, respectively. WSE can not only disrupt the integrity of the cell wall and membrane of E.coli, but also increase the permeability of the outer membrane. Conclusions Our research elucidated chemical composition and structure of WSNP, WSAP-1 and WSAP-2. WSE exerted its bactericidal activity by damaging the bacterial cell wall and membrane and increasing outer membrane permeability. Yeast cell wall products have been recommended as a potential alternative to antibiotics. This work provides more information, regarding chemical properties and anti-E. coli mechanism of WSE, and facilitates the application of yeast cell wall products as a promising antibiotic alternative in animal feed.

Cefquinome is widely used to treat respiratory tract diseases of swine. While extra-label dosages of cefquinome could improve clinical efficacy, they might lead to excessively high residues in animal-derived food. In this study, a physiologically based pharmacokinetic (PBPK) model was calibrated based on the published data and a microdialysis experiment to assess the dosage efficiency and food safety. For the microdialysis experiment, in vitro/in vivo relative recovery and concentration-time curves of cefquinome in the lung interstitium were investigated. This PBPK model is available to predict the drug concentrations in the muscle, kidney, liver, plasma, and lung interstitial fluid. Concentration-time curves of 1000 virtual animals in different tissues were simulated by applying sensitivity and Monte Carlo analyses. By integrating pharmacokinetic/pharmacodynamic target parameters, cefquinome delivered at 3–5 mg/kg twice daily is advised for the effective control of respiratory tract infections of nursery pig, which the bodyweight is around 25 kg. Based on the predicted cefquinome concentrations in edible tissues, the withdrawal interval is 2 and 3 days for label and the extra-label doses, respectively. This study provides a useful tool to optimize the dosage regimen of cefquinome against respiratory tract infections and predicts the concentration of cefquinome residues in edible tissues. This information would be helpful to improve the food safety and guide rational drug usage. Author summary Physiologically-based pharmacokinetic (PBPK) models, a mechanism-based model that incorporate physiological and chemical-specific parameters, can describe the absorption, distribution, metabolism and excretion of chemicals in different organs of animals. It can be applied for chemical risk assessment, dosage optimization and withdrawal intervals determination. The Extra-label use antimicrobial drug is a way to solve the treatment failure resulting from antimicrobial resistance. Integrate with pharmacokinetic/pharmacodynamic (PK/PD) parameters and maximum residual limit, PBPK model can determine a safe and effective dosage. This approach would be helpful to improve the food safety and guide rational drug usage.

Abstract Salmonella is a significant foodborne zoonotic pathogen that endangers both human and animal health. The goal of this research is to gain a preliminary understanding of Salmonella contamination and antimicrobial resistance in the chicken production chain in Hubei Province, China. 1149 animal and environmental samples were collected from chicken farms, slaughterhouses, and retail markets in six cities across Hubei Province in China from 2019 to 2020, yielding Salmonella isolation rates of 4.68% (28/598), 12.21% (47/385), and 9.64% (16/166), respectively. Seventeen distinct serotypes were detected among 53 non-clonal Salmonella strains, of which Meleagridis (26.42%, 14/53) was the dominant serotype. Almost half of the strains (49.06%, 26/53) were multi-drug resistant (MDR). Whole-genome sequencing (WGS) showed that 10 resistance genes (tetA, bla TEM , parC, qnrS1, floR, aac(6′)-Iy, aph(6)-Id, aph(3″)-Ib, aac(6′)-Iaa and sul2) and 7 categories of virulence genes were present in all three links in 22 non-clonal dominant serotype strains. It was shown that Salmonella in the chicken production chain in Hubei Province had a high resistance rate to Tetracycline (TET, 73.58%), Ofloxacin (OFL, 69.81%), Florfenicol (FFC, 60.38%) and Ampicillin (AMP, 39.62%) which was consistent with the widespread use of these drugs in the husbandry industry in China. Salmonella ST types determined by MLST and serotypes determined by WGS had a one-to-one correlation. Minimum spanning tree analysis revealed that there was cross contamination of Salmonella in farms and slaughterhouses, slaughterhouses and markets, animal samples and environmental samples. This work provides useful information for the prevention and control of contamination and antimicrobial resistance of Salmonella in the chicken production chain, as well as demonstrating the dependable role of WGS in Salmonella molecular typing.

Abstract Background and aim Pyrrolizidine alkaloids (PA) induced hepatic sinusoidal obstruction syndrome (HSOS) occurred worldwide and the mortality rate remained high because there were no specific therapies. Defibrotide was effective for HSOS following hematopoietic stem cell transplantation. But the pathogenesis of the two types of HSOS were not equivalent. The purpose of this study was to see if defibrotide was also effective in PA induced rat HSOS. Methods First we improved rat HSOS model by using higher dose (230 mg/kg) of monocrotaline (a kind of PA) as the dose of median lethal dose. So drug effectiveness could be assessed by survival time. Next, male SD rats were divided into 5 groups. They were control group, model group, low dose low molecular weight heparin (LMWH) treatment group, high dose LMWH treatment group and defibrotide treatment group. Rats’ survival time, liver function, white blood cell count and cytokines were compared among the groups. The DeLeve score was used to assess the severity of liver pathology. Results The model group exhibited typical liver pathology of HSOS, such as hepatic sinus dilation, congestion, endothelial injury of central lobular vein, coagulative necrosis of hepatocytes and fibrin deposition in the subendothelial. The pathologic characteristics indicated that the model was built up successfully. The survival rate was significantly higher in defibrotide group (81.8%) than model group (43.7%), while the survival rates were similar in the two LMWH groups (62.5% and 75%) and model group. The survival time only be prolonged by defibrotide (P=0.028) but not LMWH (P>0.05). DeLeve score was improved most in the defibrotide group than the two LMWH groups (both P

Abstract Background Tetramethylpyrazine (TTMP) is a flavoring additive that significantly contributes to the formation of flavor compounds in soybean-based fermented foods. Over recent years, the application of TTMP in the food industry and medicine has been widely investigated. In addition, several methods for the industrial-scale production of TTMP, including chemical and biological synthesis, have been proposed. However, there have been few reports on the synthesis of TTMP through amino acid metabolic flux. In this study, we investigated genetic alterations of arginine metabolic flux in solid-state fermentation (SSF) of soybeans with Bacillus subtilis (B.subtilis) BJ3-2 to enhance the TTMP yield. Results SSF of soybeans with BJ3-2 exhibited a strong Chi-flavour (a special flavour of ammonia-containing smelly distinct from natto) at 37 °C and a prominent soy sauce-like aroma at 45 °C. Transcriptome sequencing and RT-qPCR verification showed that the rocF gene was highly expressed at 45 °C but not at 37 °C. Moreover, the fermented soybeans with BJ3-2ΔrocF (a rocF knockout strain in B. subtilis BJ3-2 were obtained by homologous recombination) at 45 °C for 72 h displayed a lighter color and a slightly decreased pH, while exhibiting a higher arginine content (increased by 14%) than that of BJ3-2. However, the ammonia content of fermented soybeans with BJ3-2ΔrocF was 43% lower than that of BJ3-2. Inversely, the NH4 + content in fermented soybeans with BJ3-2ΔrocF was increased by 28% (0.410 mg/kg). Notably, the TTMP content in fermented soybeans with BJ3-2ΔrocF and BJ3-2ΔrocF + Arg (treated with 0.05% arginine) were significantly increased by 8.6% (0.4617 mg/g) and 18.58% (0.504 mg/g) respectively than that of the BJ3-2. Conclusion The present study provides valuable information for understanding the underlying mechanism during the TTMP formation process through arginine metabolic flux.

Because of the high research and development cost of new drugs, the long development process of new drugs, and the high failure rate at later stages, combining past drugs has gradually become a more economical and attractive alternative. However, the ensuing problem of drug–drug interactions (DDIs) urgently need to be solved, and combination has attracted a lot of attention from pharmaceutical researchers. At present, DDI is often evaluated and investigated from two perspectives: pharmacodynamics and pharmacokinetics. However, in some special cases, DDI cannot be accurately evaluated from a single perspective. Therefore, this review describes and compares the current DDI evaluation methods based on two aspects: pharmacokinetic interaction and pharmacodynamic interaction. The methods summarized in this paper mainly include probe drug cocktail methods, liver microsome and hepatocyte models, static models, physiologically based pharmacokinetic models, machine learning models, in vivo comparative efficacy studies, and in vitro static and dynamic tests. This review aims to serve as a useful guide for interested researchers to promote more scientific accuracy and clinical practical use of DDI studies.

An amendment to this paper has been published and can be accessed via the original article.

Clostridium perfringens causes significant morbidity and mortality in swine worldwide. Avilamycin showed no cross resistance and good activity for treatment of C. perfringens. The aim of this study was to formulate optimal regimens of avilamycin treatment for C. perfringens infection based on the clinical breakpoint (CBP). The wild-type cutoff value (COWT) was defined as 0.25 μg/ml, which was developed based on the minimum inhibitory concentration (MIC) distributions of 120 C. perfringens isolates and calculated using ECOFFinder. Pharmacokinetics–pharmacodynamics (PK-PD) of avilamycin in ileal content were analyzed based on the high-performance liquid chromatography method and WinNonlin software to set up the target of PK/PD index (AUC0–24h/MIC)ex based on sigmoid Emax modeling. The PK parameters of AUC0–24h, Cmax, and Tmax in the intestinal tract were 428.62 ± 14.23 h μg/mL, 146.30 ± 13.41 μg/ml,, and 4 h, respectively. The target of (AUC0–24h/MIC)ex for bactericidal activity in intestinal content was 36.15 h. The PK-PD cutoff value (COPD) was defined as 8 μg/ml and calculated by Monte Carlo simulation. The dose regimen designed from the PK-PD study was 5.2 mg/kg mixed feeding and administrated for the treatment of C. perfringens infection. Five respective strains with different MICs were selected as the infection pathogens, and the clinical cutoff value was defined as 0.125 μg/ml based on the relationship between MIC and the possibility of cure (POC) following nonlinear regression analysis, CART, and “Window” approach. The CBP was set to be 0.25 μg/ml and selected by the integrated decision tree recommended by the Clinical Laboratory of Standard Institute. The formulation of the optimal regimens and CBP is good for clinical treatment and to control drug resistance.

Diaveridine (DVD) is widely used for the prevention and treatment of coccidiosis and leucocytozoonosis infections in food-producing animals. To gain a better understanding of DVD metabolism and pharmacokinetics in healthy Landrace/Doric Cross castrated male pigs and both female and male Cobb 500 broiler chickens, a method involving radioactive tracing coupled with LC/MS-IT-TOF was developed for the identification and quantitation of DVD and its metabolites in pig and chicken plasma, and then was applied to investigate DVD pharmacokinetics. A simple MCX solid phase extraction procedure was adopted for sample preparation. After a single oral administration of 3H-DVD (10 mg/kg BW), three radioactive compounds (D0: DVD; D1: 3′-desmethyl-DVD; and D2: monoglucuronide of 3′-desmethyl-DVD) were identified in pig plasma, while only two radioactive compounds (D0 and D2) were identified in chicken plasma. In both species, the Cmax values for all detected compounds were reached at 2 h after dosing. The Cmax order was D2 (1.38 μg/ml) > D0 (0.49 μg/ml) > D1 (0.24 μg/ml) in pigs and D0 (1.55 μg/ml) > D2 (0.27 μg/ml) in chickens. The longer t1/2 (elimination half-life) of D0 contributed to the slow elimination of DVD-related compounds. The t1/2β of D0 in pigs (66.41 h) was significantly longer than that in chickens (48.30 h), but the t1/2 of total DVD-related metabolites in pigs (42.86 h) was lower than that in chickens (56.11 h). These findings suggested that the metabolism and pharmacokinetics of DVD in pigs and chickens were significantly different, and that this would affect its effectiveness, toxicology, and food safety in these animals.

Veterinary antibiotics are widely used in animal agriculture. Owing to its good absorption in the gastrointestinal tract, strong tissue permeability, and long biological half-life, doxycycline (DOX) is widely used to treat bacterial infections; however, this use can pose an environmental risk. The adsorption/desorption and degradation of DOX in three agricultural soils were investigated. DOX rapidly adsorbed to the soils, with an adsorption equilibrium time of 12 h for the three soils. The Freundlich equation was used to fit the adsorption and desorption of DOX in soils. A high Freundlich affinity coefficient (KF) was obtained from Freundlich isotherms, indicating strong sorption of DOX to agricultural soils and weak mobility to aquatic environment. Soil organic matter, the clay ratio and the cation exchange capacity were significantly positively correlated with KF (P

Illegal use of salbutamol (SAL), a β-adrenergic leanness-enhancing agent, has posed potential threat to human health in China. The excretion and depletion of SAL in pigs and goats were investigated, and the concentration correlations between edible tissues and living samples were analyzed to find out a suitable living sample for pre-slaughter monitoring of SAL in pigs and goats. After a single oral dosage of 1.2 mg/kg SAL, approximately 70% of the dose was excreted by pigs and goats from their excreta. When pigs and goats were supplied feed containing SAL (20 mg/kg) for 14 consecutive days, high concentrations of SAL were observed in the liver and kidneys, and the longest persistence was observed in hair. Unlike pigs, SAL was presented primarily as conjugated SAL in goats. Excellent concentration correlations of SAL were observed between urine and edible tissues both in pigs and goats, and in addition, good correlations also were found between hair and edible tissues in pigs and between feces and edible tissues in goats. Hence, urine and hair could accurately predict SAL concentrations in edible tissues of pigs, whereas feces and urine were satisfactory for predicting SAL concentrations in edible tissues of goats. These data make it possible for pre-slaughter monitoring of SAL residues in the edible tissues of pigs and goats.

Cephalosporins are one of the most widely used antibiotics. When cephalosporins are discharged into the environment, they not only induce the production of antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARBs) but also cause toxic effects on animals and plants. Due to their complicated environmental behavior and lack of relevant data, the environmental behavior remains unclear. In this study, the adsorption-desorption and degradation characteristics of the third-generation cephalosporin drug ceftiofur (CEF) were investigated in three agricultural soils (sandy loam, loam and clay). According to the relevant parameters of the Freundlich adsorption isotherm (the Kf range was 57.63–122.44 μg1–1/n L1/n kg−1), CEF was adsorbed moderately in the soils and had the potential to migrate into groundwater. CEF exhibited low persistence in the soils and faster degradation than other antibiotics, such as tetracyclines and fluoroquinolones. The degradation half-lives (DT50) of CEF in soils ranged from 0.76 days to 4.31 days. Adding feces, increasing the water content, providing light and increasing the temperature significantly accelerated the degradation of CEF in soils. The DT50 values of CEF in soils were significantly prolonged when the soils were sterilized, indicating that both physical degradation and biodegradation played important roles in the degradation of CEF in soils. The DT50 values of CEF in soils were significantly prolonged at high concentrations, indicating that the degradability of CEF in soils was affected by the initial concentration. No significant differences were observed in the DT50 values for the different soil types (p > 0.05). This study provides useful information about the environmental behavior of CEF and improves the environmental risk assessment of CEF.

The aim of this study was to explore the prudent use of tylosin for the treatment of chronic respiratory infectious diseases in chickens caused by Mycoplasma gallisepticum (MG) based on its clinical breakpoint (CBP) and its effect on lung microbiota. The CBP was established based on the wild-type/epidemiological cutoff value (COWT/ECV), pharmacokinetics-pharmacodynamics (PK-PD) cutoff value (COPD), and clinical cutoff value (COCL) of tylosin against MG. The minimum inhibitory concentration (MIC) of tylosin against 111 MG isolates was analyzed and the COWT was 2 μg/ml. M17 with MIC of 2 μg/ml was selected as a representative strain for the PK-PD study. The COPD of tylosin against MG was 1 μg/ml. The dosage regimen formulated by the PK-PD study was 3 days administration of tylosin at a dose of 45.88 mg/kg b.w. with a 24-h interval. Five different MIC MGs were selected for clinical trial, and the COCL of tylosin against MG was 0.5 μg/ml. According to the CLSI decision tree, the CBP of tylosin against MG was set up as 2 μg/ml. The effect of tylosin on lung microbiota of MG-infected chickens was analyzed by 16S rRNA gene sequencing. Significant change of the lung microbiota was observed in the infection group and treatment group based on the principal coordinate analysis and the Venn diagrams of the core and unique OTU. The phyla Firmicutes and Proteobacteria showed difference after MG infection and treatment. This study established the CBP of tylosin against MG. It also provided scientific data for the prudent use of tylosin based on the evaluation of MG infection and tylosin treatment on the lung microbiota.

The presence of hypertension (HTN) in type 2 diabetes mellitus (DM) is a common phenomenon in more than half of the diabetic patients. Since HTN constitutes a predictor of vascular complications and cardiovascular disease in type 2 DM patients, it is of significance to understand the molecular and cellular mechanisms of type 2 DM binding to HTN. This review attempts to understand the mechanism via the perspective of the metabolites. It reviewed the metabolic perturbations, the biological function of perturbated metabolites in two diseases, and the mechanism underlying metabolic perturbation that contributed to the connection of type 2 DM and HTN. DM-associated metabolic perturbations may be involved in the pathogenesis of HTN potentially in insulin, angiotensin II, sympathetic nervous system, and the energy reprogramming to address how perturbated metabolites in type 2 DM affect the pathogenesis of HTN. The recent integration of the metabolism field with microbiology and immunology may provide a wider perspective. Metabolism affects immune function and supports immune cell differentiation by the switch of energy. The diverse metabolites produced by bacteria modified the biological process in the inflammatory response of chronic metabolic diseases either. The rapidly evolving metabolomics has enabled to have a better understanding of the process of diseases, which is an important tool for providing some insight into the investigation of diseases mechanism. Metabolites served as direct modulators of biological processes were believed to assess the pathological mechanisms involved in diseases.

Glaesserella parasuis (G. parasuis) causes Glasser’s disease in pigs and causes high mortality in piglets. The new drug Aditoprim (ADP) alone or combined with Sulfamethoxazole (SMZ) is one of the good choices for treating respiratory infections. The objective of this study was to recommend the optimal dosing regimen for the treatment of G. parasuis infection which contains resistance and virulence genes by ADP/SMZ compound through pharmacokinetics–pharmacodynamics (PK-PD) modeling. The whole genome of the virulent strain G. parasuis H78 was obtained and annotated by whole genome sequencing. The results show that G. parasuis H78 consists of a unilateral circular chromosome with prophages in the genome. The annotation results of G. parasuis H78 showed that the genome contained a large number of virulence-related genes and drug resistance-related genes. The in vitro PD study showed that the antibacterial effect of ADP/SMZ compound against G. parasuis was time-dependent, and AUC/MIC was selected as the PK-PD modeling parameter. The PK study showed that the content of ADP/SMZ compound in pulmonary epithelial lining fluid (PELF) was higher than plasma, and there were no significant differences in ADP and SMZ PK parameters between the healthy and infected group. The dose equation to calculate the optimal dosing regimen of ADP/SMZ compound administration for control of G. parasuis infection was 5/25 mg/kg b.w., intramuscular injection once a day for 3~5 consecutive days. The results of this study provide novel therapeutic options for the treatment of G. parasuis infection to decrease the prevalence and disease burden caused by G. parasuis.

As an emerging novel drug carrier, nanoparticles provide a promising way for effective treatment of parasitic diseases by overcoming the shortcomings of low bioavailability, poor cellular permeability, nonspecific distribution and rapid elimination of antiparasitic drugs from the body. In recent years, some kinds of ideal nanocarriers have been developed for antiparasitic drug delivery. In this review, the progress of the enhanced antiparasitic effects of different nanoparticles payload and their influencing factors were firstly summarized. Secondly, the transport and disposition process in the body were reviewed. Finally, the challenges and prospects of nanoparticles for antiparasitic drug delivery were proposed. This review will help scholars to understand the development trend of nanoparticles in the treatment of parasitic diseases and explore strategies in the development of more efficient nanocarriers to overcome the difficulty in the treatment of parasite infections in the future.

The hollow fiber cartridge has the advantages of good semi-permeability, high surface area to volume ratio, convenient operation, and so on. Its application in chemical analysis, drug in vitro experiment, hemodialysis, and other fields has been deeply studied. This paper introduces the basic structure of hollow fiber cartridge, compares the advantages and disadvantages of a hollow fiber infection model constructed by a hollow fiber cartridge with traditional static model and animal infection model and introduces its application in drug effects, mechanism of drug resistance, and evaluation of combined drug regimen. The principle and application of hollow fiber bioreactors for cell culture and hollow fiber dialyzer for dialysis and filtration were discussed. The hollow fiber cartridge, whether used in drug experiments, artificial liver, artificial kidney, etc., has achieved controllable experimental operation and efficient and accurate experimental results, and will provide more convenience and support for drug development and clinical research in the future.

The depletion profiles of olaquindox and its six major metabolites, including O1 (N1-deoxyolaquindox), O2 (deoxyolaquindox), O3 (2-carboxamide-3-methylquinoxaline-N4-oxide), O4 (2-carboxymethylaminocarbonyl-3-methylquinoxaline-N4-oxide), O5 (2-carboxymethylaminocarbonyl-3-methylquinoxaline), and O6 [3-methyl-quinoxaline-2-carboxylic acid (MQCA)] were studied with a sensitive and accurate HPLC-UV method in pigs and broilers after oral administration of olaquindox at the rate of 50 mg kg−1 feed for 14 consecutive days. Five medicated pigs and six medicated broilers and one control animal for each time point were anesthetized and killed at different time points (6 h and 1, 3, 7, and 14 days for pigs and 6 h and 1, 3, 5, and 7 days for broilers) after ingestion of the medicated feed ceased and samples of muscle, liver, kidney, and fat were collected. The samples were assayed using a liquid chromatographic method. Mean concentrations of O2 (deoxyolaquindox) metabolite residues in all tissues of pigs were higher than other metabolite residues at each time point. MQCA was detected at lower concentrations and eliminated more rapidly than deoxyolaquindox (calculated t1/2 1.78–2.28 days vs. t1/2 2.04–2.46 days). The elimination half-lives of deoxyolaquindox residue in broilers' liver and kidney tissues (t1/2 >4 days) were much longer than those in pigs. Thus, the use of olaquindox in poultry is clearly inappropriate, as significant drug residues will occur without a withdrawal time. The results that deoxyolaquindox occurs at higher concentrations in kidney tissue and is more persistent than other residues in edible tissues of pigs which indicate that deoxyolaquindox is the most relevant marker residue and should be monitored in the routine surveillance of olaquindox-related residues in foods of animal origin.

The study was to explore the rational use of danofloxacin against Mycoplasma gallisepticum (MG) based on its clinical breakpoint (CBP) and the effect on lung microbiota. The CBP was established according to epidemiological cutoff value (ECV/COWT), pharmacokinetic–pharmacodynamic (PK–PD) cutoff value (COPD) and clinical cutoff value (COCL). The ECV was determined by the micro-broth dilution method and analyzed by ECOFFinder software. The COPD was determined according to PK–PD modeling of danofloxacin in infected lung tissue with Monte Carlo analysis. The COCL was performed based on the relationship between the minimum inhibitory concentration (MIC) and the possibility of cure (POC) from clinical trials. The CBP in infected lung tissue was 1 μg/mL according to CLSI M37-A3 decision tree. The 16S ribosomal RNA (rRNA) sequencing results showed that the lung microbiota, especially the phyla Firmicutes and Proteobacteria had changed significantly along with the process of cure regimen (the 24 h dosing interval of 16.60 mg/kg b.w for three consecutive days). Our study suggested that the rational use of danofloxacin for the treatment of MG infections should consider the MIC and effect of antibiotics on the respiratory microbiota.

Model informed drug development is a valuable tool for drug development and clinical application due to its ability to integrate variability and uncertainty of data. This study aimed to determine an optimal dosage of ceftiofur against P. multocida by ex vivo pharmacokinetic/pharmacodynamic (PK/PD) model and validate the dosage regimens by Physiological based Pharmacokinetic-Pharmacodynamic (PBPK/PD) model. The pharmacokinetic profiles of ceftiofur both in plasma and bronchoalveolar lavage fluid (BALF) are determined. PD performance of ceftiofur against P. multocida was investigated. By establishing PK/PD model, PK/PD parameters and doses were determined. PBPK model and PBPK/PD model were developed to validate the dosage efficacy. The PK/PD parameters, AUC0–24 h/MIC, for bacteriostatic action, bactericidal action and elimination were determined as 44.02, 89.40, and 119.90 h and the corresponding dosages were determined as 0.22, 0.46, and 0.64 mg/kg, respectively. AUC24 h/MIC and AUC 72 h/MIC are simulated by PBPK model, compared with the PK/PD parameters, the therapeutic effect can reach probability of target attainment (PTA) of 90%. The time-courses of bacterial growth were predicted by the PBPK/PD model, which indicated the dosage of 0.46 mg/kg body weight could inhibit the bacterial growth and perform good bactericidal effect.

Streptococcus suis (S. suis) causes severe respiratory diseases in pigs and is also an important pathogen causing hidden dangers to public health and safety. Acetylkitasamycin is a new macrolide agent that has shown good activity to Gram-positive cocci such as Streptococcus. The purpose of this study was to perform pharmacokinetic–pharmacodynamic (PK-PD) modeling to formulate a dosing regimen of acetylkitasamycin for treatment of S. suis and to decrease the emergence of acetylkitasamycin-resistant S. suis. The minimal inhibitory concentration (MIC) of 110 S. suis isolates was determined by broth micro dilution method. The MIC50 of the 55 sensitive S. suis isolates was 1.21 μg/mL. The strain HB1607 with MIC close to MIC50 and high pathogenicity was used for the PK-PD experiments. The MIC and MBC of HB1607 in both MH broth and pulmonary epithelial lining fluid (PELF) was 1 and 2 μg/mL, respectively. The liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was used to determine the concentration change of acetylkitasamycin in piglet plasma and PELF after intragastric administration of a single dose of 50 mg/kg b.w. acetylkitasamycin. The PK parameters were calculated by WinNolin software. The PK data showed that the maximum concentration (Cmax), peak time (Tmax), and area under the concentration–time curve (AUC) were 9.84 ± 0.39 μg/mL, 4.27 ± 0.19 h and 248.58 ± 21.17 h·μg/mL, respectively. Integration of the in vivo PK data and ex vivo PD data, an inhibition sigmoid Emax equation was established. The dosing regimen of acetylkitasamycin for the treatment S. suis infection established as 33.12 mg/kg b.w. every 12 h for 3 days. This study provided a reasonable dosing regimen for a new drug used in clinical treatment, which can effectively be used to treat S. suis infection and slow down the generation of drug resistance.

Tuberculosis and fungal infections can pose serious threats to human health. In order to find novel antimicrobial agents, 26 novel quinoxaline-1,4-di-N-oxides containing a thiazolidinone moiety were designed and synthesized, and their antimycobacterial activities were evaluated. Among them, compounds 2t, 2u, 2y, and 2z displayed the most potent antimycobacterial activity against Mycobacterium tuberculosis strain H37Rv (minimal inhibitory concentration [MIC] = 1.56 μg/mL). The antifungal activity of all the compounds was also evaluated against Candida albicans, Candida tropicalis, Aspergillus fumigatus, and Cryptococcus neoformans. Compounds 2t, 2u, 2y, and 2z exhibited potential antifungal activities, with an MIC between 2 and 4 μg/mL. Comparative molecular field analysis (CoMFA: q2 = 0.914, r2 = 0.967) and comparative molecular similarity index analysis (CoMSIA: q2 = 0.918, r2 = 0.968) models were established to investigate the structure and antimycobacterial activity relationship. The results of contour maps revealed that electronegative and sterically bulky substituents play an important role in the antimycobacterial activity. Electronegative and sterically bulky substituents are preferred at the C7 position of the quinoxaline ring and the C4 position of the phenyl group to increase the antimycobacterial activity. Additionally, more hydrogen bond donor substituents should be considered at the C2 side chain of the quinoxaline ring to improve the activity.

Antibiotics-induced changes in intestinal flora (dysbiosis) may have various effects on the host. Dysbiosis is associated with numerous metabolites including bile acids, which are produced in the liver from cholesterol and metabolized in the gut by intestinal microbiota. Total phenolic extracts of Citrus aurantium L. (TPE-CA) are rich in dietary flavanones and their glycosyl derivatives, including flavones, flavonols, polymethoxyflavones and coumarins, which exert positive health effects on the microbiota. The aim of this study is to elucidate the interplays between the intestinal microbiota and bile acids metabolism attributed to antibiotics. Mice were exposed to broad-spectrum antibiotics, such as ampicillin, streptomycin and clindamycin, for 14 days. This exposure resulted in reduced bacterial diversity and richness, and destroyed intestinal permeability. The homeostasis of bile acids was also affected. Subsequent TPE-CA administration, counteracted most of the dysbiosis, and reshaped intestinal permeability, these effects occurred via upregulation of zonula occludens 1 and occludin associated proteins and downregulation of serum endotoxin compared to the antibiotics group. TPE-CA maintained the homeostasis of bile acids via modulation of the liver–gut axis related farnesoid X receptor (FXR)/fibroblast growth factor 15 (FGF15) pathway and FXR-targeted protein. Our findings indicated that TPE-CA exerted a protective effect on the restoration of intestinal microbiota composition, reshaped barrier integrity and maintained bile acid homeostasis via the liver–gut axis with antibiotics-induced dysbiosis.

Antimicrobial resistance is a major public health issue. The pharmacokinetic/pharmacodynamic (PK/PD) model is an essential tool to optimize dosage regimens and alleviate the emergence of resistance. The semi-mechanistic PK/PD model is a mathematical quantitative tool to capture the relationship between dose, exposure, and response, in terms of the mechanism. Understanding the different resistant mechanisms of bacteria to various antibacterials and presenting this as mathematical equations, the semi-mechanistic PK/PD model can capture and simulate the progress of bacterial growth and the variation in susceptibility. In this review, we outline the bacterial growth model and antibacterial effect model, including different resistant mechanisms, such as persisting resistance, adaptive resistance, and pre-existing resistance, of antibacterials against bacteria. The application of the semi-mechanistic PK/PD model, such as the determination of PK/PD breakpoints, combination therapy, and dosage optimization, are also summarized. Additionally, it is important to integrate the PD effect, such as the inoculum effect and host response, in order to develop a comprehensive mechanism model. In conclusion, with the semi-mechanistic PK/PD model, the dosage regimen can be reasonably determined, which can suppress bacterial growth and resistance development.

Streptococcus suis (S. suis), a zoonotic pathogen, causes severe diseases in both pigs and human beings. Cefquinome can display excellent antibacterial activity against gram-negative and gram-positive bacteria. The aim of this study was to derive an optimal dosage of cefquinome against S. suis with a pharmacokinetic/pharmacodynamic (PK/PD) integration model in the target infection site and to investigate the cutoffs monitoring the changes of resistance. The minimum inhibitory concentration (MIC) distribution of cefquinome against 342 S. suis strains was determined. MIC50 and MIC90 were 0.06 and 0.25 μg/mL, respectively. The wild-type cutoff was calculated as 1 μg/mL. A two-compartmental model was applied to calculate the main pharmacokinetic parameters after 2 mg/kg cefquinome administered intramuscularly. An optimized dosage regimen of 3.08 mg/kg for 2-log10 CFU reduction was proposed by ex vivo PK/PD model of infected swine. The pharmacokinetic-pharmacodynamic cutoff was calculated as 0.06 μg/mL based on PK/PD targets. Based on the clinical effectiveness study of pathogenic MIC isolates, the clinical cutoff was calculated as 0.5 μg/mL. A clinical breakpoint was proposed as 1 μg/mL. In conclusion, the results offer a reference for determining susceptibility breakpoint of cefquinome against S. suis and avoiding resistance emergence by following the optimal dosage regimen.

Abstract Metronidazole (MNZ) is used in veterinary medicine for the treatment of anaerobic infections and a variety of protozoal and parasitic diseases. Current study has been conducted to examine the disposition and residue depletion studies of MNZ and its main metabolites in pigs and broilers. After a single oral administration of MNZ, the concentrations of MNZ and its main metabolites in the excreta of pigs and broilers were determined by LC-MS/MS. More than 75% of the drug was recovered within 14 days, of which MNZ accounted for about 40%, MNZ-OH 20–25% and MAA less than 10%. The residue depletion study showed that MNZ was the most predominant residue in all of the tissues and could be detected in liver, kidney and muscle up to the withdrawal time of 14 days. MNZ-OH concentrations were lower than MNZ in all of the tissues, but its elimination half-life was close to MNZ. It is proposed that kidney and muscle are appropriate residue target tissues and both MNZ and its hydroxylated metabolite, MNZ-OH, should be monitored in the routine surveillance of MNZ related residues in food of animal origin.

Abstract The purpose of this study was to evaluate the activity of cyadox against Clostridium perfringens in swine and optimize the dosage regimen using ex vivo pharmacokinetic-pharmacodynamic (PK-PD) modeling. After oral administration, the ileum fluid of pigs containing the free cyadox was collected by implanted ultrafiltration probes. The Tmax, AUC24h, and CL/F of free cyadox in the ileum fluid were 1.96 h, 106.40 μg/h/mL, and 0.27 L/kg/h, respectively. Cyadox displayed a concentration-dependent killing action against C. perfrignens. The minimum inhibitory concentration (MIC) of cyadox against 60 clinical isolates ranged from 0.5 to 8 μg/mL, with MIC50 and MIC90 values of 2 and 4 μg/mL, respectively. The MIC was 2 μg/mL against the pathogenic C. perfrignens isolate CPFK122995 in both broth and ileum fluid. According to the inhibitory sigmoid Emax modeling, the AUC24h/MIC ratios of ileum fluid required to achieve the bacteriostatic, bactericidal, and virtual bacterial elimination effects were 26.72, 39.54, and 50.69 h, respectively. Monte Carlo simulations for the 90% target attainment rate (TAR) predicted daily doses of 29.30, 42.56, and 54.50 mg/kg over 24 h to achieve bacteriostatic, bactericidal, and elimination actions, respectively. The results of this study suggest that cyadox is a promising antibacterial agent for the treatment of C. perfringens infections, and can be used to inform its clinical use.

Abstract Background Rice vinegar (RV) and white vinegar (WV) as daily flavoring, have also used as accessory in traditional Chinese medicine processing. As we know, the promoting blood circulation efficiency could be enhanced when herbs processed by vinegar. Number of reports focused on health benefits derived by consumption of vinegar. However, few concerned the blood circulation bioactivity. Methods In this paper, a metabolomics guided strategy was proposed to elaborate on the chemical constituents’ variation of two kinds of vinegar. GC–MS coupled with multivariate statistical analysis were conducted to analyze the chemical components in RV and WV and discriminate these two kinds of vinegar. The anti-platelet activities in vitro were investigated by whole blood aggregometry platelet test. And the anticoagulant activities were monitored by the whole blood viscosity, plasma viscosity, packed cell volume, prothrombin time, and four coagulation tests (PT, TT, APTT, FIB) in vivo. Results Constituents of RV and WV were globally characterized and 33 potential biomarkers were identified. The contents of four potential alkaloid biomarkers increased with aging time prolonged in RV. RV and its alkaloids metabolites exhibited some anti-platelet effects in vitro and anticoagulant activities in vivo. WV failed to exhibit promoting effects. Conclusions Alkaloid metabolites were demonstrated to be the principal compounds contributing to discrimination and it increased with aging time prolonged in RV. RV exhibited the blood circulation bioactivity. The alkaloids of RV contributed to the blood circulation bioactivity. Graphical abstract The diagram of metabolomics guided promoting blood circulation bioactivity compounds screening strategy

Abstract An increase in number of newly developed synthetic drugs displays bioavailability constraints because of poor water solubility. Nanosuspensions formulation may help to overwhelm these problems by increasing dissolution velocity and saturation solubility. In the present study, cyadox (Cyx) nanosuspension was successfully prepared by recrystallization based on acid–base neutralization combined with high pressure homogenization method using Polyvinylpyrrolidone K30 (PVP) as stabilizer. The nanosuspension had uniform particle distribution, excellent sedimentation rate and redispersibility. The nanosuspension significantly improved the solubility, dissolution and bioavailability. The saturation solubility of Cyx nanocrystal was higher than that of bulk Cyx and released the total drug in very short time. Further, pharmacokinetics of Cyx nanosuspension and normal suspension following oral administration was investigated in beagle dogs. Nanosuspension improved the bioavailability of Cyx which could be beneficial for intestinal bacterial infection in animals. Maximum concentration and area under concentration time curve were increased with particles size reduction which might give rise to pronounce fluctuations in plasma concentration and more intensified antibacterial effects. The terminal half-life and mean resident time of Cyx nanosuspension had also increased compared to normal Cyx suspension. In conclusion, nanosuspensions may be a suitable delivery approach to increase the bioavailability of poorly soluble drugs.

Our previous study has showed that a novel gene is differentially expressed in the liver of cyadox-fed piglets, but its sequence and function are unknown. Here, rapid amplification of cDNA ends (RACE) and bioinformatics analysis showed that the novel gene is 953 bp without protein-coding ability and locates in chromosome 11. Hence, we identified the novel gene as long non-coding RNA (lncRNA) and named it cyadox-related novel gene (CRNG). Fluorescence in situ hybridization (FISH) showed that CRNG mainly distributes in cytoplasm. Moreover, microarray assay in combination with CRNG interference and overexpression showed that the differential genes such as ANPEP, KITLG, STAT5A, FOXP3, miR-451, IL-2, IL-10, IL-6, and TNF-α are mainly involved in viral and pathogens infection and the immune-inflammatory responses in PK-15 cells. This work reveals that CRNG might play a role in preventing the host from being infected by pathogens and viruses and exerting immune regulatory effects in the cytoplasm, which may be involved in prophylaxis of cyadox in piglets.

A broad-spectrum microbiological inhibition method has been developed for rapidly screening different kinds of antibiotics such as β-lactam, aminoglycosides, tetracyclines, sulfonamides, macrolides, lincosamides and quinolones in milk, chicken egg and honey by using an easy sample preparation. The microbiological system in microtiter plates consists of an agar medium, a mixture of nutrients, test bacteria (Geobacillus stearothermophilus var C953), bromocresol purple, and other supplements such as trimethoprim, chloramphenicol, streptomycin and enrofloxacin which helps to improve the detection capability of the microbiological system toward the chosen antibiotics. It was observed that the limit of detection of the kit used in present study for all kinds of antibiotics in milk were lower than or close to maximum residue limits determined by EU or CODEX. For chicken egg and honey, the detection capability of the kit was similar to that determined in milk. Moreover, it was revealed that the kit in present study was more sensitive to aminoglycosides, macrolides and quinolones in various matrixes than internationally available commercial kits. The false-positive and false-negative rates for both were 0%. The coefficient of variations among various factors was all less than 4%. Additionally, the quality guarantee period of the kit was more than 6 months at 4°C. A good correlation between the kit results and the LC–MS/MS results for milk was also observed, which revealed that the kit was reliable to screen antibiotics residues in incurred samples.

In-depth research on processing can promote the globalization of processed herbs. The purpose of this study is to propose an improved strategy for processing effect investigation. Frankincense and processed frankincense were used as research subjects. First, high-speed countercurrent chromatography (HSCCC) and preparation high-performance liquid chromatography (PHPLC) techniques were used for major compounds isolation and minor compounds concentration. Processed frankincense was subjected to two stepwise solvent systems, namely, n-hexane:ethanol:water (6:5:1) and n-hexane:methyl-acetate:acetonitrile:water (4:4:3:4), to yield 12 fractions, and 18 compounds were further separated. Second, a comprehensive metabolomic analysis conducted by ultrahigh-performance liquid-chromatography/electrospray-ionization mass spectrometry (UHPLC-Qtof-MS) coupled with multivariate statistics was performed to fully characterize the chemical components and discover the potential biomarkers between frankincense and processed frankincense. In total, 81 metabolites, including the 18 separated compounds, were selected as potential biomarkers between frankincense and processed frankincense among 153 detected compounds for their VIP values of greater than one. The tirucallane-type compounds and components with 9,11-dehydro structures clearly occurred at high levels in the processed frankincense, while lupine-type compounds and those with 11-keto structures were significantly higher in frankincense. Then, a network pharmacology model was constructed to decipher the potential mechanisms of processing. Intestinal absorption properties prediction indicated the possibility of processing-related absorption enhancement. A systematic analysis of the constructed networks showed that the C-T network was constructed with 18 potential biomarkers and 69 targets. TNF and IL-1β were among the top-ranked and were linked by 8 and 7 pathways, which were mainly involved in inflammation. The arachidonic acid metabolism pathway exhibited the highest number of target connections. Finally, the prediction was validated experimentally by an intestinal permeability and efficacy assay. The experiments provided convincing evidence that processed frankincense harbored stronger inhibition effects toward TNF-α-, IL-1β- and arachidonic acid-induced platelet aggregation. The processing procedure leads to changes of the chemical metabolites, which triggers the enhancement of absorption and cure efficiency. The global change of the metabolites, absorption and pharmacological effects of processing were depicted in a systematic manner.

Cyadox has potential use as an antimicrobial agent in animals. However, its pharmacodynamic properties have not been systematically studied yet. In this study, the in vitro antibacterial activities of cyadox were assayed, and the antibacterial efficacy of cyadox against facultative anaerobes was also determined under anaerobic conditions. It was shown that Clostridium perfringens and Pasteurella multocida (MIC = 0.25 and 1 μg/mL) from pigs, Campylobacter jejuni and Pasteurella multocida from poultry, E. coli, Streptococcus spp., and Flavobacterium columnare from fish were highly susceptible to cyadox (MIC= 1 and 8 μg/mL). However, F. columnare has no killing effect for drug tolerance. Under in vitro anaerobic conditions, the antibacterial activity of cyadox against most facultative anaerobes was considerably enhanced Under anaerobic conditions for the facultative anaerobes, susceptible bacteria were P. multocida, Aeromonas spp. (including A. hydrophila, A. veronii, A. jandaei, A. caviae, and A. sobria, excluding A. punctata), E. coli, Salmonella spp. (including S. choleraesui, S. typhimurium, and S. pullorum), Proteus mirabilis, Vibrio fluvialis, Yersinia ruckeri, Erysipelothrix, Acinetobacter baumannii, and Streptococcus agalactiae (MICs were 0.25~8 μg/mL, MBCs were 1–64 μg/mL). Intermediate bacteria were Enterococcus spp. (including E. faecalis and E. faecium), Yersinia enterocolitica, and Streptococcus spp. (MICs mainly were 8~32 μg/mL, MBCs were 16~128 μg/mL). This study firstly showed that cyadox had strong antibacterial activity and had the potential to be used as a single drug in the treatment of bacterial infectious diseases.

Haemophilus parasuis can cause high morbidity and mortality in swine. Cefquinome possesses excellent antibacterial activity against pathogens causing diseases of the respiratory tract. This study aimed to establish the clinical breakpoint (CBP) of cefquinome against H. parasuis and to monitor the resistance change. Referring to the minimum inhibitory concentration (MIC) distribution of cefquinome against 131 H. parasuis isolates, the MIC50 and MIC90 were determined to be 0.125 and 1 μg/mL, respectively. And the epidemiological cutoff (ECOFF) value was 1 μg/mL. HPS42 was selected as a representative strain for the pharmacodynamic (PD) experiment, pharmacokinetic (PK) experiment and clinical experiments. The PK/PD index values, area under concentration-time curve (AUC)/MIC, of the bacteriostatic, bactericidal, and bacterial elimination effects were 23, 41, and 51 h, respectively. The PK/PD cutoff was calculated as 0.125 μg/mL by Monte Carlo simulation (MCS), and the clinical cutoff was 0.25−4 μg/mL by WindoW. Combing these three values, the CBP of cefquinome against H. parasuis was found to be 1 μg/mL. In conclusion, this was the first study to integrate various cutoffs to establish the CBP in the laboratory. It is helpful to distinguish wild type H. parasuis and reduce the probability of treatment failure.

With the widespread application of wireless sensor networks (WSNs), WSN virtualization technology has received extensive attention. A key challenge in WSN virtualization is the survivable virtual network embedding (SVNE) problem which efficiently maps a virtual network on a WSN accounting for possible substrate failures. Aiming at the lack of survivability research towards physical sensor node failure in the virtualized sensor network, the SVNE problem is mathematically modeled as a mixed integer programming problem considering resource constraints. A heuristic algorithm—node reliability-aware backup survivable embedding algorithm (NCS)—is further put forward to solve this problem. Firstly, a node reliability-aware embedding method is presented for initial embedding. The resource reliability of underlying physical sensor nodes is evaluated and the nodes with higher reliability are selected as mapping nodes. Secondly, a fault recovery mechanism based on resource reservation is proposed. The critical virtual sensor nodes are recognized and their embedded physical sensor nodes are further backed up. When the virtual sensor network (VSN) fails caused by the failure physical node, the operation of the VSN is restored by backup switching. Finally, the experimental results show that the strategy put forward in this paper can effectively guarantee the survivability of the VSN, reduce the failure penalty caused by the physical sensor nodes failure, and improve the long-term operating income of infrastructure provider.

Previous studies have demonstrated differential perception of body expressions between males and females. However, only two recent studies (Kret et al., 2011; Krüger et al., 2013) explored the interaction effect between observer gender and subject gender, and it remains unclear whether this interaction between the two gender factors is gender-congruent (i.e., better recognition of emotions expressed by subjects of the same gender) or gender-incongruent (i.e., better recognition of emotions expressed by subjects of the opposite gender). Here, we used event-related potentials (ERPs) to investigate the recognition of fearful and angry body expressions posed by males and females. Male and female observers also completed an affective rating task (including valence, intensity, and arousal ratings). Behavioral results showed that male observers reported higher arousal rating scores for angry body expressions posed by females than males. ERP data showed that when recognizing angry body expressions, female observers had larger P1 for male than female bodies, while male observers had larger P3 for female than male bodies. These results indicate gender-incongruent effects in early and later stages of body expression processing, which fits well with the evolutionary theory that females mainly play a role in care of offspring while males mainly play a role in family guarding and protection. Furthermore, it is found that in both angry and fearful conditions male observers exhibited a larger N170 for male than female bodies, and female observers showed a larger N170 for female than male bodies. This gender-incongruent effect in the structural encoding stage of processing may be due to the familiarity of the body configural features of the same gender. The current results provide insights into the significant role of gender in body expression processing, helping us understand the issue of gender vulnerability associated with psychiatric disorders characterized by deficits of body language reading.

This paper presents a convenient and sensitive LC-MS/MS method for the simultaneous determination of carbadox and olaquindox residues, including desoxyolaquindox (DOLQ), desoxycarbadox (DCBX), quinoxaline-2-carboxylic acid (QCA), 3-methyl-quinoxaline-2-carboxylic acid (MQCA), and the glycine conjugates of QCA and MQCA (namely, QCA-glycine and MQCA-glycine, resp.) in swine muscle and liver tissues. Tissue samples were extracted with 2% metaphosphoric acid in 20% methanol and cleaned up by solid-phase extraction (SPE) on a mixed-mode anion-exchange column (Oasis MAX). Analysis was performed on a C18 column by detection with mass spectrometry in the multiple reaction monitoring (MRM) mode. The limits of detection (LODs) of the six analytes were determined to be 0.01 μg·kg−1 to 0.25 μg·kg−1, and the limits of quantification (LOQs) were 0.02 μg·kg−1 to 0.5 μg·kg−1. The total recoveries of the six analytes in all tissues were higher than 79.1% with the RSD% less than 9.2%. The developed method can determine the real residue level of QCA and MQCA, whether they are present in free form or as glycine conjugates in tissues, together with the carcinogenic desoxy metabolites DCBX and DOLQ with high recovery. Therefore, this method was suitable for routine analysis of residue control programmes and the residue depletion study of CBX and OLQ on swine.

Campylobacter jejuni is one of the most common foodborne pathogen worldwide. A putative transcriptional regulator, Cj0440c, was up-regulated in the erythromycin-resistant C. jejuni, however, the precise role of Cj0440c is yet to be determined. The aim of this study was to determine the biological functions of Cj0440c. The Cj0440c isogenic mutants were constructed from erythromycin-susceptible C. jejuni NCTC 11168 (S) and -resistant C. jejuni 68-ER (R), designating as SM and RM, respectively. The isogenic Cj0440c mutants (SM and RM) and parental strains (S and R) were subjected to microarray and qRT-PCR analysis to examine the transcriptional profile changes contributed by Cj0440c. The antimicrobial susceptibility, flagellar morphology, in vitro growth and in vivo colonization in chickens were carried out to analyze the biological function of Cj0440c. The results showed that 17 genes were down-regulated in SM compared to S, while 9 genes were down-regulated in RM compared to R. The genes with transcriptional change were mainly involved in flagella biosynthesis and assembly. Using transmission electron microscopy, we found that the filaments were impaired in SM and lost in RM. The chicken colonization experiments showed that Cj0440c mutants (SM and RM) had reduced colonization ability in chickens when compared with corresponding parental strains (S and R). In conclusion, Cj0440c regulates flagella biosynthesis and assembly, and consequently affect the in vivo colonization of erythromycin-susceptible and -resistant C. jejuni.

Quinoxaline 1,4-di-N-oxides (QdNOs) are a class of bioreductive compounds, however their antibacterial mechanisms are still unclarified. The aim of this study was to assess the ability of two representative QdNO drugs, cyadox (CYA) and olaquindox (OLA), to produce reactive oxide species (ROS) in Gram-positive anaerobe Clostridium perfringens CVCC1125 and Gram-negative anaerobe Brachyspira hyodysenteriae B204. In addition, the effects of QdNOs on the integrity of bacterial cell walls and membranes as well as the morphological alterations and DNA oxidative damage in C. perfringens and B. hyodysenteriae were analyzed. It was demonstrated that under anaerobic conditions, QdNOs were metabolized into the reduced products which did not show any antibacterial activity. A significant dose-related increase of intracellular ROS level and intracellular hydroxyl radicals were evident in bacteria exposed to QdNOs. The result of biochemical assay showed that the cell walls and membranes of the bacteria treated with QdNOs were damaged. After exposure to 1/2MIC to 4MIC of CYA and OLA, C. perfringens and B. hyodysenteriae became elongated and filamentous. Morphological observation with scanning and transmission electron microscopes revealed rupture, loss of cytoplasmic material and cell lysis in QdNO-treated bacteria, indicating serious damage of cells. There was an increase of 8-OHdG in the two strains treated by QdNOs, but it was lower in Gram-positive than in Gram-negative bacteria. Agarose gel electrophoresis showed the degradation of chromosomal DNA in both of the two anaerobes treated by QdNOs. The results suggest that QdNOs may kill C. perfringens and B. hyodysenteriae via the generation of ROS and hydroxyl radicals from the bacterial metabolism of QdNOs, which cause oxidative damage in bacteria under anaerobic conditions.

Boswellic acids (BAs), as the main components of frankincense, exhibit notable anti-inflammatory properties. However, their pharmaceutical development has been severely limited by their poor oral bioavailability. Traditional Chinese medicinal processing, called Pao Zhi, is believed to improve bioavailability, yet the mechanism is still completely unclear. Previous research suggested that the bioavailability of a drug can be influenced by physical properties. This paper was designed to investigate the physical properties of frankincense and processed frankincense, including the surface morphology, particle size, polydispersity index (PDI), zeta potential (ZP), specific surface area, porosity, and viscosity. The differences in the intestinal absorption characteristics and equilibrium solubilities between frankincense and processed frankincense were determined by an ultra-high-performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry (UHPLC-TQ-MS) analysis method. The results showed that vinegar processing can alter the surface morphology, decrease the particle size and PDI, raise the absolute values of the ZP, specific surface area and porosity, and drop the viscosity of frankincense. Meanwhile, the rates of absorption and dissolution of the main BAs were increased after the processing of frankincense. The present study proves that the physical properties were changed after processing, in which case the bioavailability of frankincense was enhanced.

The aim of this study was to reveal the molecular mechanism involved in multidrug resistance and virulence of Campylobacter jejuni isolated from broiler chickens. The virulence of six multidrug resistant C. jejuni was determined by in vitro and in vivo methods. The de novo whole genome sequencing technology and molecular biology methods were used to analyze the genomic features associated with the multidrug resistance and virulence of a selected isolate (C. jejuni 1655). The comparative genomic analyses revealed a large number of single nucleotide polymorphisms, deletions, rearrangements, and inversions in C. jejuni 1655 compared to reference C. jejuni genomes. The co-emergence of Thr-86-Ile mutation in gyrA gene, A2075G mutation in 23S rRNA gene, tetO, aphA and aadE genes and pTet plasmid in C. jejuni 1655 contributed its multidrug resistance to fluoroquinolones, macrolides, tetracycline and aminoglycosides. The combination of multiple virulence genes may work together to confer the relative higher virulence in C. jejuni 1655. The co-existence of mobile gene elements (e.g. pTet) and CRISPR-Cas system in C. jejuni 1655 may play an important role in the gene transfer and immune defense. The present study provides basic information of phenotypic and genomic features of C. jejuni 1655, a strain recently isolated from a chicken displaying multidrug resistance and relatively high level of virulence.

Cyadox (Cyx) is an antibacterial drug of the quinoxaline group that exerts markedly lower toxicity in animals, compared to its congeners. Here, the pharmacokinetics and metabolism of Cyx after oral (PO), intramuscular (IM) and intravenous (IV) routes of administration were studied to establish safety criteria for the clinical use of Cyx in animals. Six beagle dogs (3 males, 3 females) were administered Cyx through PO (40 mg kg-1 b.w.), IM (10 mg kg-1 b.w.) and IV (10 mg kg-1 b.w.) routes with a washout period of 2 weeks in a crossover design. Highly sensitive high-performance liquid chromatography with ultraviolet detection (HPLC-UV) was employed for determination of Cyx and its main metabolites, 1, 4-bisdesoxycyadox (Cy1), cyadox-1-monoxide (Cy2), N-(quinoxaline-2-methyl)-cyanide acetyl hydrazine (Cy4) and quinoxaline-2-carboxylic acid (Cy6) in plasma, urine and feces of dogs. The oral bioavailability of Cyx was 4.75%, suggesting first-pass effect in dogs. The concentration vs. time profile in plasma after PO administration indicates that Cyx is rapidly dissociated into its metabolites and eliminated from plasma earlier, compared to its metabolites. The areas under the curve (AUC) of Cyx after PO, IM and IV administration were 1.22 h×µg mL-1, 6.3 h×µg mL-1, and 6.66 h×µg mL-1, while mean resident times (MRT) were 7.32, 3.58 and 0.556 h, respectively. Total recovery of Cyx and its metabolites was >60% with each administration route. In feces, 48.83% drug was recovered after PO administration, while 18.15% and 17.11% after IM and IV injections, respectively, suggesting renal clearance as the major route of excretion with IM and IV administration and feces as the major route with PO delivery. Our comprehensive evaluation of Cyx has uncovered detailed information that should facilitate its judicious use in animals by improving understanding of its pharmacology.

A novel and aqueous gel-casting process has been successfully developed to fabricate porous MgAl2O4 ceramics by using hydratable alumina and MgO powders as raw materials and deionized water as hydration agent. The effects of different amounts of deionized water on the hydration properties, apparent porosity, bulk density, microstructure, pore size distribution and compressive strength of the samples were investigated. The results indicated that the porosity and the microstructure of porous MgAl2O4 ceramics were governed by the amounts of deionized water added. The porous structure was formed by the liberation of physisorbed water and the decomposition of hydration products such as bayerite, brucite and boehmite. After determining the addition amounts of deionized water, the fabricated porous MgAl2O4 ceramics had a high apparent porosity (52.5–65.8%), a small average pore size structure (around 1–3 μm) and a relatively high compressive strength (12–28 MPa). The novel aqueous gel-casting process with easy access is expected to be a promising candidate for the preparation of Al2O3-based porous ceramics.

Quinoxaline 1,4-di-N-oxides (QdNOs) are widely known as potent antibacterial agents, but their antibacterial mechanisms are incompletely understood. In this study, the transcriptomic and proteomic profiles of Escherichia coli exposed to QdNOs were integratively investigated, and the results demonstrated that QdNOs mainly induced an SOS response and oxidative stress. Moreover, genes and proteins involved in the bacterial metabolism, cellular structure maintenance, resistance and virulence were also found to be changed, conferring bacterial survival strategies. Biochemical assays showed that reactive oxygen species were induced in the QdNO-treated bacteria and that free radical scavengers attenuated the antibacterial action of QdNOs and DNA damage, suggesting an oxidative-DNA-damage action of QdNOs. The QdNO radical intermediates, likely carbon-centered and aryl-type radicals, as identified by electron paramagnetic resonance, were the major radicals induced by QdNOs, and xanthine oxidase was one of the QdNO-activating enzymes. This study provides new insights into the action of QdNOs in a systematic manner and increases the current knowledge of bacterial physiology under antibiotic stresses, which may be of great value in the development of new antibiotic-potentiating strategies.

Xanthine oxidoreductase (XOR) is a cytoplasmic molybdenum-containing oxidoreductase, catalyzing both endogenous purines and exogenous compounds. It is suggested that XOR in porcine hepatocytes catalyzes the N-oxide reduction of quinoxaline 1,4-di-N-oxides (QdNOs). To elucidate the molecular mechanism underlying this metabolism, the cDNA of porcine XOR was cloned and heterologously expressed in Spodoptera frugiperda insect cells. The bovine XOR, showing sequence identity of 91% to porcine XOR, was employed as template for homology modeling. By docking cyadox, a representative compound of QdNOs, into porcine XOR model, eight amino acid residues, Gly47, Asn352, Ser360, Arg427, Asp430, Asp431, Ser1227 and Lys1230, were located at distances of less than 4Å to cyadox. Site-directed mutagenesis was performed to analyze their catalytic functions. Compared with wild type porcine XOR, G47A, S360P, D431A, S1227A, and K1230A displayed altered kinetic parameters in cyadox reduction, similarly to that in xanthine oxidation, indicating these mutations influenced electron-donating process of xanthine before subsequent electron transfer to cyadox to fulfill the N-oxide reduction. Differently, R427E and D430H, both located in the 424-434 loop, exhibited a much lower K(m) and a decreased V(max) respectively in cyadox reduction. Arg427 may be related to the substrate binding of porcine XOR to cyadox, and Asp430 is suggested to be involved in the transfer of electron to cyadox. This study initially reveals the possible catalytic mechanism of porcine XOR in cyadox metabolism, providing with novel insights into the structure-function relationship of XOR in the reduction of exogenous di-N-oxides.

Pattern classification is a key approach in Traditional Chinese Medicine (TCM), and it is used to classify the patients for intervention selection accordingly. TCM cold and heat patterns, two main patterns of rheumatoid arthritis (RA) had been explored with systems biology approaches. Different regulations of apoptosis were found to be involved in cold and heat classification in our previous works. For this study, the metabolic profiling of plasma was explored in RA patients with typical TCM cold or heat patterns by integrating liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS) platforms in conjunction with the Ingenuity Pathway Analysis (IPA) software. Three main processes of metabolism, including amino acid, carbohydrate and lipid were focused on for function analysis. The results showed that 29 and 19 differential metabolites were found in cold and heat patterns respectively, compared with healthy controls. The perturbation of amino acid metabolism (increased essential amino acids), carbohydrate metabolism (galactose metabolism) and lipid metabolism, were found to be involved in both cold and heat pattern RA. In particular, more metabolic perturbations in protein and collagen breakdown, decreased glycolytic activity and aerobic oxidation, and increased energy utilization associated with RA cold pattern patients. These findings may be useful for obtaining a better understanding of RA pathogenesis and for achieving a better efficacy in RA clinical practice.