Pharmacokinetics of danofloxacin after single oral and intravenous administration in non-laying hens.

The current study aimed to explore the pharmacokinetics of danofloxacin in non-laying hens after a single oral (PO) and intravenous (IV) dose, both at 5 mg/kg body weight (BW). Eighteen 13-week-old healthy hens were equally and randomly divided into two groups. After both doses, blood samples (approximately 1 ml) were collected at different time points. Danofloxacin concentrations were quantified by a validated high-performance liquid chromatography (HPLC) method followed by a non-compartmental analysis using the software of WinNonLin. The elimination half-lives (t1/2λz s) after PO and IV routes were determined as 8.15 ± 3.37 and 7.69 ± 3.40 h, respectively. After IV administration, danofloxacin had an initial concentration (C0 ) of 3.62 µg/ml, a volume of distribution at steady state (VSS ) of 3579.72 ± 454.29 ml/kg, and a total body clearance (Cl) of 0.49 ml/h/g. After PO administration, the absolute bioavailability and absorption half-life (t1/2ka ) were calculated as 100.99% ± 23.10% and 0.82 ± 0.58 h, respectively. Based on the calculated ratio values of AUC/MIC and Cmax /MIC, an oral dose of 5 mg/kg danofloxacin would be expected to successfully treat hens infected with strains with MIC values ≤0.1 µg/ml.

Metagenomic insights into the antibiotic resistomes of typical Chinese dairy farm environments.

Antibiotic resistance genes (ARGs) in the environment pose a threat to human and animal health. Dairy cows are important livestock in China; however, a comprehensive understanding of antibiotic resistance in their production environment has not been well clarified. In this study, we used metagenomic methods to analyze the resistomes, microbiomes, and potential ARG bacterial hosts in typical dairy farm environments (including feces, wastewater, and soil). The ARGs resistant to tetracyclines, MLS, ß-lactams, aminoglycoside, and multidrug was dominant in the dairy farm ecosystem. The abundance and diversity of total ARGs in dairy feces and wastewater were significantly higher than in soil (P < 0.05). The same environmental samples from different dairy have similar resistomes and microbiomes. A high detection rate of tet(X) in wastewater and feces (100% and 71.4%, respectively), high abundance (range from 5.74 to 68.99 copies/Gb), and the finding of tet(X5) challenged the clinical application of the last antibiotics resort of tigecycline. Network analysis identified Bacteroides as the dominant genus in feces and wastewater, which harbored the greatest abundance of their respective total ARG coverage and shared ARGs. These results improved our understanding of ARG profiles and their bacterial hosts in dairy farm environments and provided a basis for further surveillance.

Shifts of Antibiotic Resistomes in Soil Following Amendments of Antibiotics-Contained Dairy Manure.

Dairy manure is a nutrition source for cropland soils and also simultaneously serves as a contamination source of antibiotic resistance genes (ARGs). In this study, five classes of antibiotics including aminoglycosides, beta-lactams, macrolides, sulfonamides, and tetracyclines, were spiked in dairy manure and incubated with soil for 60 days. The high throughput qPCR and 16S rRNA amplicon sequencing were used to detect temporal shifts of the soil antibiotic resistomes and bacterial community. Results indicated dairy manure application increased the ARG abundance by 0.5-3.7 times and subtype numbers by 2.7-3.7 times and changed the microbial community structure in soils. These effects were limited to the early incubation stage. Selection pressure was observed after the addition of sulfonamides. Bacterial communities played an important role in the shifts of ARG profiles and accounted for 44.9% of the resistome variation. The incubation period, but not the different antibiotic treatments, has a strong impact on the bacteria community. Firmicutes and Bacteroidetes were the dominant bacterial hosts for individual ARGs. This study advanced our understanding of the effect of dairy manure and antibiotics on the antibiotic resistome in soils and provided a reference for controlling ARG dissemination from dairy farms to the environment.

Residue Depletion of Imidocarb in Bovine Tissues by UPLC-MS/MS.

In this study, an ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the residue depletion of imidocarb (IMD) in bovine tissues, and the drug withdrawal time of IMD was determined. Twenty-five clinically healthy cattle (body weight 300 kg ± 15 kg) were randomly divided into five groups of five cattle each. The cattle were treated subcutaneously injecting a single dose of a generic IMD formulation, at the recommended dosage of 3.0 mg/kg. The five groups of cattle were slaughtered respectively at 96, 160, 198, 213, and 228 days after IMD administration. Samples from the liver, kidney, muscle, fat, and injection site were collected from each animal. After subtilis proteinase was used to digest the tissue, the content of IMD in the samples was analyzed by UPLC-MS/MS method. In conclusion, the method validation results showed that the method meets the criteria, and the longest withdrawal time of 224 days for the liver can be selected as the conclusive withdrawal time to guarantee consumer safety.

Does coal-to-gas policy reduce air pollution? Evidence from a quasi-natural experiment in China.

Whether the use of cleaner energy can reduce air pollution is the focus of debate among scholars, but there is still no unanimous conclusion. This study seeks to explore the net impact of coal-to-gas policy, an energy transition policy in China, on air pollution. Utilizing prefecture-level city data from 2003 to 2016, we apply the PSM-DID method to estimate the policy's net impact. Further, we examine the dynamic effects of coal-to-gas policy and its impact mechanism on air pollution. The results show that 1) The coal-to-gas policy has an average reduction effect of 31.3%, 36%, 0.3%, and 33.1% on industrial sulfur dioxide (SO2), industrial Smoke (dust), fine particulate matter (PM2.5), and air quality index (AQI). After eliminating the spreading interference of PM2.5 in surrounding areas, the effect of this policy on PM2.5 reduction is 7%; 2) the impact of the coal-to-gas policy is significant in 2012 and 2013, i.e. the second and third years after the implementation of the policy. Then, the reduction effect of the policy on air pollution began to decrease; 3) the coal-to-gas policy has led to the increase in the proportion of the tertiary industry and the decrease in the degree of industrialization. Since the development of the tertiary industry and the reduction of industrialization also led to a reduction in air pollution, the coal-to-gas policy can reduce air pollution through industrial structure upgrading and de-industrialization. The robustness test results support the above conclusions. Practicable policies to reduce air pollution in China are suggested and applicable to other developing countries with resource-scarce and serve air pollution.

Energy carbon emission structure and reduction potential focused on the supply-side and demand-side.

In recent years, the environmental problems caused by excessive carbon emissions from energy sources have become increasingly serious, which not only aggravates the climate change caused by the greenhouse effect but also seriously restricts the sustainable development of Chinese economy. An attempt is made in this paper to use energy consumption method and input-output method to study the carbon emission structure of China's energy system and industry in 2015 from two perspectives, namely China's energy supply side and energy demand side, by taking into account the two factors of energy invest in gross capital formation and export. The results show that neglecting these two factors will lead to underestimation of intermediate use carbon emissions and overestimation of final use carbon emissions. On energy supply side, the carbon emission structure of China's energy system is still dominated by high-carbon energy (raw coal, coke, diesel, and fuel oil, etc.), accounting for more than 70% of total energy carbon emissions; on the contrary, the natural gas such as clean energy accounts for only 3.45% of total energy carbon emissions, indicating that the energy consumption structure optimization and emission reduction gap of China's energy supply side are still substantial. On energy demand side, the final use (direct consumption by residents and government) produces less carbon emissions, while the intermediate use (production by enterprises) produces more than 90% of the total energy carbon emissions. Fossil energy, power sector, heavy industry, chemical industry, and transportation belong to industries with larger carbon emissions and lower carbon emission efficiency, while agriculture, construction, light industry, and service belong to industries with fewer carbon emissions and higher carbon emission efficiency. This means that the optimization of industrial structure is conducive to slowing down the growth of energy carbon emissions on the demand side.

Preparation and evaluation of enrofloxacin microspheres and tissue distribution in rats.

New enrofloxacin microspheres were formulated, and their physical properties, lung-targeting ability, and tissue distribution in rats were examined. The microspheres had a regular and round shape. The mean diameter was 10.06 µm, and the diameter of 89.93% of all microspheres ranged from 7.0 µm to 30.0 µm. Tissue distribution of the microspheres was evaluated along with a conventional enrofloxacin preparation after a single intravenous injection (7.5 mg of enrofloxacin/kg bw). The results showed that the elimination half-life (t1/2ß) of enrofloxacin from lung was prolonged from 7.94 h for the conventional enrofloxacin to 13.28 h for the microspheres. Area under the lung concentration versus time curve from 0 h to ∞ (AUC00∞) was increased from 11.66 h·µg/g to 508.00 h·µg/g. The peak concentration (Cmax) in lung was increased from 5.95 µg/g to 93.36 µg/g. Three lung-targeting parameters were further assessed and showed that the microspheres had remarkable lung-targeting capabilities.