Pharmacokinetic–pharmacodynamic modelling for the determination of optimal dosing regimen of florfenicol in Nile tilapia (Oreochromis niloticus) at different water temperatures and antimicrobial susceptibility levels

Optimized dosing regimen is key to the effective use of antibacterials and to minimizing drug‐related side effects. The current study established a pharmacokinetic–pharmacodynamic (PK‐PD) model for the determination of optimal antibacterial dosing regimen in fish taken into consideration the temperature‐dependent PK and the pathogen‐dependent antimicrobial susceptibility, using florfenicol (FF) in Nile tilapia as an example. The calculated optimal dosages significantly varied by temperature and target MIC levels, ranging from 2.23 (MIC 1 µg/ml at 24°C) to 34.88 mg kg^?1 day^?1 (MIC 4 µg/ml at 32°C). The appropriateness of the calculated dosages was successfully verified by the in vivo studies. After 5 days of oral administration of the calculated optimal dosage at 24°C, the predicted plasma drug values were in line with the mean observed C_min(ss) while at 28 and 32°C underestimation of the C_min(ss) in a dose‐dependent manner was observed and likely due to the occurrence of non‐linear PK at high dosages. The averaged serum protein binding of FF was 19.1%. Our results demonstrated the appropriateness and clinical applicability of the developed PK‐PD approach for the determination of optimal dosing regimens at given temperatures and MICs. Saturation metabolism and PK non‐linearity of FF in tilapia warrant further study.     

叠加法拟定给药方案的理论和实例

叠加法是工程技术上经常运用的数学方法,移植到药物代谢动力学领域用作简便的拟定给药方案的非房室法。文章依据药动学原理系统地推导和定义了应用该法拟定给药方案所必需的若干数学式子,并以作者试验材料为例,介绍如何正确运用这些式子制定合理的给药方案。     

夏商周时期的森林生态思想简析

夏、商与西周三代,是中国古代文明由兴起到繁盛的重要历史时期。先民们为了发展农业而大面积毁林开荒,砍伐林木以满足生产生活需要,致使破坏森林资源的程度越来越严重,并时常引发生态危害。为了节制森林利用和减缓生态破坏,更有效地保护利用森林资源,产生了某些较原始的关于森林利用和生态保护的思想意识,包括对森林动植物的图腾崇拜,五行学说对“木”的认识,阴阳学说与生态安全,森林与生态资源持续利用等思想。在这些朴素的生态思想意识的支配和指导下,相对加强了对森林生态资源的保护和管理。     

盐酸沙拉沙星在蛋鸡体内的血液动力学的研究

为研究盐酸沙拉沙星在蛋鸡体内血液动力学 ,选用成年健康蛋鸡 6 5只进行试验。按 10mg/kg体重口服给药后 ,测定血清中盐酸沙拉沙星的含量。结果表明 :盐酸沙拉沙星在血液中经时过程符合一级吸收一室模型 ,其理论方程为Cb=1.0 36 (e-0 .173 5t-e-2 .0 57t)。Ka 为 1.6 0 2 5h-1、Cmax为 0 .74 2 9μg/mL、tmax为 1.5 80 7h。由抗生素后效应及药动学参数 ,建议临床给药口服方案为 10 .12mg/kg。     

Growth Performance,Meat Yield,and Economic Responses of Broilers Fed Diets Varying in Metabolizable Energy from Thirty to Fifty-Nine Days of Age

Two studies examined responses of broilers to diets varying in AME from 30 to 59 d of age. A 59-d termination allows for evaluation of energy needs applicable to “big bird” programs, because research on nutritional needs for such programs is warranted. Two experiments were conducted: experiment (exp.) 1 having low temperatures whereas exp. 2 used moderate temperatures. The treatments in exp. 1 and 2 were AME concentrations ranging from 3,175 to 3,310 kcal/kg with CP, TSAA, and Lys being identical across all treatments. In exp. 2, an additional treatment consisted of a diet containing 3,310 kcal of AME/kg with CP, TSAA, and Lys being increased by 4% of those specifications used in the other treatments so as to minimize differences in energy:CP ratio.In both experiments, feed consumption and conversion decreased linearly as dietary AME increased, but breast meat yield was reduced with the high AME diet and only increasing amino acids in exp. 2 ameliorated the negative effect. Live production costs and gross feeding margin (bird return over feed costs) were optimized in exp. 1 with 3,220 kcal of AME/kg of diet, but 3,310 kcal of AME/kg of diet and increased amino acids were needed in exp. 2 for improved monetary returns. In both experiments, broilers had similar caloric consumption indicating that these broilers can compensate to varying dietary AME concentrations within practical limits. These results demonstrated that the response to dietary AME was more pronounced under moderate ambient temperatures.     

Dietary regimen of the woodpigeon (Columba palumbus)

Recently, new agricultural policies and European Directives brought to important changes in farming practice, some of which could affect food availability for the wild bird population endangering biodiversity. This study aims to evaluate the consequences of such agricultural changes in France on the woodpigeon's dietary regimen. A total of 1,093 woodpigeons were collected over a four-year period (2014–2017). Voluntary sampling was performed in six regions in the south-west of France by local hunters during this species’ autumnal migration and wintering. Ingluvies contents were recovered, macroscopically and microscopically identified, and then weighed before and after drying. Five food groups were identified: acorns, corn, green plant material, cultivated seeds and others. ANOVA testing followed by Tukey's test for multiple comparison were performed (R version 3.5.2). Significance was set at p < .05. A total of 762 woodpigeons met the study's inclusion criteria. Mean weight of total crop contents was less of 9 grams of dry matter. Most frequent food groups were “green plant material” (70.3%), acorns (42.3%) and corn (27.2%). In terms of grams of dry matter, the most important food in the crop content were acorns (62%): these were eaten more during the first two hunting seasons (p < .001), and in region A, lower amount was consumed compared to all other regions. On the contrary, corn intake peaked during the third year (p < .001), and in region A, birds had an increasing intake of this cereal. Cultivated seeds contributed to the diet more during migration (p = .007), while “green plant material” and others more during wintering (p = .011; p = .004). In conclusion, results confirm the opportunistic nature of the woodpigeon, balancing its diet according to food availability. Corn was eaten more in areas where the winter burying of chopped maize stover (mulching), provided by the Nitrate's directive, was in derogation.     

氟甲喹在大菱鲆体内的药代动力学研究

为探讨氟甲喹在大菱鲆体内的药代动力学特征,在水温14~17℃条件下,以20 mg/kg的剂量静脉注射和口服氟甲喹,分别于给药后15、30 min和1、2、4、6、8、12、16、24、36、48、72、96 h采血及各组织,利用高效液相色谱法测定血浆和各组织中的氟甲喹含量,采用DAS 2.0药动学软件中统计矩方法分析药代动力学参数。结果显示,静注给药后,血浆中氟甲喹的表观分布容积为5.46 L/kg,消除半衰期为56.93 h,曲线下面积、生物利用度分别为220.32 h·mg/L、100%;口服给药后,血浆中氟甲喹的曲线下面积、生物利用度分别为95.85 h·mg/L和43.51%,达峰时间为16 h,表观分布容积为4.21 L/kg,消除半衰期为14.12 h。结果表明,静注和口服氟甲喹在大菱鲆体内组织分布均较广,但静注消除慢,口服吸收差、消除快。口服给药后,血浆中氟甲喹浓度在24 h内高于对常见病菌的抑菌浓度,因此,每天以20 mg/kg的剂量给药1次,可对常见细菌疾病起到较好防治效果。