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Enrofloxacin (ENR) is effective in the prevention and treatment of bacterial infections caused by various fish pathogenic bacteria such as Aeromonas spp., Vibrio spp., Nocardia and Yersinia spp. The purpose of this work was to explore the pharmacokinetics (PK), tissue distribution, and depletion of ENR and its main metabolite, ciprofloxacin (CIP), in northern snakehead (Channa argus) reared at 25 °C during and after repeated oral dose of 10 mg/kg animal body weight per day for a total of 5 days. ENR and CIP concentrations were simultaneously determined in the plasma, liver, kidney, gill, and muscle with adhering skin by HPLC with fluorescence detection. Using a non-compartmental analysis, PK parameters were derived from the mean concentration versus time data of ENR and CIP. The results showed a slow absorption, long half-life and wide tissue distribution of ENR in the northern snakehead. The maximum concentrations of ENR in the plasma, muscle plus skin, liver, kidney, and gill tissues were observed at 3, 6, 6, 6, and 9 h post treatment, respectively, and the corresponding depletion half-lives (T1/2z) were 78.00, 83.24, 82.56, 126.07, and 68.70 h, respectively. The extent of ENR distribution into the tissues followed the decreasing order of liver > kidney > gill > plasma > muscle plus skin. The highest concentrations of both ENR and CIP were observed in the liver, suggesting that liver is the major site of ENR metabolism in northern snakehead. The Cmax/MIC and AUC24/MIC ratios obtained in the present study indicated that the ENR regimen employed would be effective in treatment of infections caused by susceptible strains with MIC values below 0.7 μg/mL. Based on the calculation results, a reasonable withdrawal period should not be less than 18 days at 25 °C for ENR in northern snakehead after treatment ceased.

The Asian giant softshell turtle, Pelochelys cantorii, is endangered and has been designated as a first-grade protected animal in China. This article reports the results of a study on the reproductive biology of Asian giant softshell turtles. Two individuals, a male and a female from the Suijiang River in Guangning County, Guangdong Province, were introduced into captivity 8 yrs ago. The 2 turtles have engaged in mating activity since April 2014, and the female laid a total of 66 eggs in 2014 (25 eggs on 15 June, 22 eggs on 30 June, and 19 eggs on 14 July). The egg laying took an average of 50.6 min. Egg shape was spherical, and mean (± SD) egg mass was 13.27 ± 0.97 g, with mean diameter 2.90 ± 0.12 cm. The viability rate was 46% and the hatching rate 33%, and only 10 neonates successfully hatched. Hatchling body weight averaged 10.0 ± 0.56 g, carapace length averaged 42.25 ± 3.69 mm, carapace width averaged 40.25 ± 1.58 mm, and carapace height averaged 12.54 ± 0.91 mm. The juvenile turtles diffe...

The pharmacokinetics of cefquinome was studied in plasma after a single dose (10 mg/kg) of intramuscular (i.m.) or intraperitoneal (i.p.) administration to tilapia (Oreochromis niloticus) in freshwater at 30 °C. Ten fish per sampling point were examined after treatment. The data were fitted to two-compartment open models following both routes of administration. The estimates of total body clearance (CL/F), volume of distribution (Vd/F), and absorption half-life (T1/2ka ) were 0.049 and 0.037 L/h/kg, 0.41 and 0.33 L/kg, and 0.028 and 0.035 h following i.m. and i.p. administration, respectively. After i.m. injection, the elimination half-life (T1⁄2β ) was calculated to be 5.81 h, the maximum plasma concentration (Cmax ) to be 49.40 μg/mL, the time to peak plasma cefquinome concentration (Tmax ) to be 0.14 h, and the area under the plasma concentration-time curve (AUC) to be 204.6 μg h/mL. Following i.p. administration, the corresponding estimates were 6.05 h, 44.39 μg/mL, 0.17 h and 267.8 μg h/mL. The minimum inhibitory concentrations of cefquinome, determined for 30 strains of Streptococcus agalactiae isolated from diseased tilapia, ranged from 0.015 to 0.12 μg/mL. Results from these studies support that 10 mg cefquinome/kg body weight daily could be expected to control tilapia bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of ≤2 μg/mL.

The single-dose disposition kinetics of the antibiotic marbofloxacin were determined in Chinese soft-shelled turtles (n = 10) after oral and intramuscular (i.m.) dose of 10 mg/kg bodyweight. The in vitro and ex vivo activities of marbofloxacin in serum against a pathogenic strain of Aeromonas hydrophila were determined. A concentration-dependent antimicrobial activity of marbofloxacin was confirmed for levels lower than 4 × MIC. For in vivo PK data, values of AUC: minimum inhibitory concentration (MIC) ratio for serum were 1166.6 and 782.4 h, respectively, after i.m. and oral dosing of marbofloxacin against a pathogenic strain of A. hydrophila (MIC = 0.05 μg/mL). The ex vivo growth inhibition data after oral dosing were fitted to the inhibitory sigmoid Emax equation to provide the values of AUC/MIC required to produce bacteriostasis, bactericidal activity and elimination of bacteria. The respective values were 23.79, 36.35 and 126.46 h. It is proposed that these findings might be used with MIC50 or MIC90 data to provide a rational approach to the design of dosage schedules, which optimize efficacy in respect of bacteriological as well as clinical cures.

China is the largest freshwater aquaculture producer and antibiotics consumer in the world, and rivers in China are generally polluted by antibiotics. However, there is little information available regarding the linkage of antibiotics in aquaculture and the aquatic environment. Therefore, this study investigated the fate of antibiotics in several open water culture-based freshwater aquafarms, including integrated livestock/fish systems and non-integrated fish ponds, and explored the contamination profiles of antibiotics in the Beijiang River. Then the study tried to clarify the two-way interaction of antibiotics in aquaculture and the environment. The results showed that, when compared with the effluent from livestock farms and wastewater treatment plants, the contribution of antibiotics from non-integrated fish pond water without livestock sewage input was limited, while that of effluent from the integrated livestock/fish system was quite high. The total concentrations of antibiotics detected in the aquafarm source water were similar to those in the upper river water and generally higher than those in the corresponding fish pond water, implying that the occurrence of antibiotics in intensive aquafarms can mainly be attributed to the antibiotic residues in nearby river water. Overall, the results underscore the need to develop a sewage infrastructure for the treatment of effluent from integrated livestock/fish aquafarms, and suggest that open water culture-based fish farms should be located far from seriously contaminated sections of rivers.

Powder coating is a dry coating technology, which has several advantages over conventional liquid coatings. However, wider applications were limited by its inferior surface finish and increased film thickness. Making powder finer (fine powder technology) can provide much better surface appearance and smaller film thickness comparable to liquid coating, but it’s much more difficult to produce fine powder products with narrow particle size distributions than coarse powder. Another issue that restricts the applications is its electrostatic spraying method, which limits the applications mainly to be with conductive substrates, like metals. In this study, to ensure a narrow particle size distribution of fine powder products, nine kinds of modification were conducted with the classifier of widely-used air classifying mill (ACM) by changing the air flow through it. For each kind of modification, the experiments were conducted under five operating conditions and were repeated for three times. According to the results of 150 samples, the particle sizes and particle size distributions of products were greatly affected by the classifier configuration. All nine kinds of modification showed better performance than the original classifier on narrowing particle size distributions, without compromising any collection efficiency. In addition, non-conductive plastics were employed as substrates in fine powder experiments, using two popular commercial coating powders. Results showed that lowering the particle sizes and narrowing particle size distributions of coating powders contributed to better surface finishes on the workpieces. Besides, due to the poor flowability of fine powder, different amounts of flow additives were used with fine coating powders, and the optimum amount of additives was selected considering the effects on both flowability and surface quality. Furthermore, utilizing voltage was proven to be an effective method assisting pre-heating to increase transfer efficiency.

The pharmacokinetics of enrofloxacin (ENR) was studied in crucian carp (Carassius auratus gibelio) after single administration by intramuscular (IM) injection and oral gavage (PO) at a dose of 10 mg/kg body weight and by 5 mg/L bath for 5 hr at 25°C. The plasma concentrations of ENR and ciprofloxacin (CIP) were determined by HPLC. Pharmacokinetic parameters were calculated based on mean ENR or CIP concentrations using WinNonlin 6.1 software. After IM, PO and bath administration, the maximum plasma concentration (Cmax) of 2.29, 3.24 and 0.36 μg/ml was obtained at 4.08, 0.68 and 0 hr, respectively; the elimination half-life (T1/2β) was 80.95, 62.17 and 61.15 hr, respectively; the area under the concentration–time curve (AUC) values were 223.46, 162.72 and 14.91 μg hr/ml, respectively. CIP, an active metabolite of enrofloxacin, was detected and measured after all methods of drug administration except bath. It is possible and practical to obtain therapeutic blood concentrations of enrofloxacin in the crucian carp using IM, PO and bath immersion administration.

The Asian giant softshell turtle, Pelochelys cantorii (Trionychidae), is endangered and was designated as a First Grade Protected Animal in China in 1989 and listed as Endangered on the International Union for Conservation of Nature Red List in 2000; the species has suffered a gradual reduction in its range, its total population has decreased, and the need to protect this species has been ignored. We investigated 13 nature reserves with P. cantorii as the main object of protection and 5 captive-breeding centers; we also present the results from a questionnaire sent to one nature reserve. We summarize the distribution and habitat characteristics, evaluate the species' conservation status in each nature reserve, analyze the causes of extinction, and put forward our proposal for the protection of P. cantorii.

To enhance the operational safety of civil aviation, based on the data of civil aviation unsafe incidents on 2006-2015, the assessment index was constructed with typical accident and incident events, and the operational safety risk assessment model based on grey whitening clustering was proposed in this paper. Then the weight of each index is determined by the principle of maximizing deviation. Finally, the safety risk in these 10 years was evaluated by actual operation data. According to the result, it was consistent with the actual operation of civil aviation, which verified the rationality of the safety risk assessment indexes taking into account of the typical accidents and incidents. It had changed the traditional safety assessment index and methods of civil aviation based on people, machines, environment and administration, which had positive significance to improve the safety production capacity of civil aviation.