Disposition Kinetics of Difloxacin After Intravenous,Intramuscular and Subcutaneous Administration in Calves

The pharmacokinetics of difloxacin (Dicural) was studied in a crossover study using three groups (n = 4) of male and female Friesian calves after intravenous (i.v.), intramuscular (i.m.) and subcutaneous (s.c.) administrations of 5 mg/kg body weight. Drug concentration in plasma was determined by high-performance liquid chromatography using fluorescence detection. The plasma concentration–time data following i.v. administration were best fitted to a two-compartment open model and those following i.m. and s.c. routes were best fitted using one-compartment open model. The collected data were subjected to a computerized kinetic analysis. The mean i.v., i.m. and s.c. elimination half-lives (t _1/2β) were 5.56 ± 0.33 h, 6.12 ± 0.42 h and 7.26 ± 0.6 h, respectively. The steady-state volume of distribution (V _dss) was 1.12 ± 0.09 L/kg and total body clearance (Cl_B) was 2.19 ± 0.1 ml/(min. kg). The absorption half lives (t _1/2ab) were 0.38 ± 0.027 h and 2.1 ± 0.09 h, with systemic bioavailabilities (F) of 96.5% ± 6.4% and 84% ± 5.5% after i.m. and s.c. administration, respectively. After i.m. and s.c. dosing, peak plasma concentrations (C _max) of 3.38 ± 0.13 μg/ml and 2.18 ± 0.12 μg/ml were attained after (t _max) 1.22 ± 0.20 h and 3.7 ± 0.52 h. The MIC₉₀ of difloxacin for Mannheimia haemolytica was 0.29 ± 0.04 μg/ml. The AUC/MIC₉₀ and C _max/MIC₉₀ ratios for difloxacin following i.m. administration were 120 and 11.65, respectively and following s.c. administration were 97.58 and 7.51, respectively. Difloxacin was 31.7–36.8% bound to calf plasma protein. Since fluoroquinolones display concentration-dependent activities, the doses of difloxacin used in this study are likely to involve better pharmacodynamic characteristics that are associated with greater clinical efficacy following i.m. administration than following s.c. administration.     

Differential susceptibility to tetracycline,oxytetracycline and doxycycline of the calf pathogens Mannheimia haemolytica and Pasteurella multocida in three growth media

For clinical isolates of bovine Mannheimia haemolytica and Pasteurella multocida, this study reports minimum inhibitory concentration (MIC) differences for tetracycline, oxytetracycline and doxycycline between cation‐adjusted Mueller‐Hinton broth (CAMHB), foetal bovine serum (FBS) and Roswell Park Memorial Institute (RPMI) medium. MICs were determined according to CLSI standards and additionally using five overlapping sets of twofold dilutions. Matrix effect: (a) free drug MICs and minimum bactericidal concentrations (MBC) for all drugs were significantly higher in FBS than in CAMHB for both pathogens (p < 0.001); (b) MICs and MBCs were higher for CAMHB and FBS compared to RPMI for P. multocida only. Net growth rate for P. multocida in CAMHB was significantly slower than in FBS and higher than in RPMI, correlating to MIC and MBC ranking. Drug effect: doxycycline MICs and MBCs were significantly lower (p < 0.001) in both CAMHB and FBS than tetracycline and oxytetracycline for both pathogens. Only for M. haemolytica were oxytetracycline MIC and MBC significantly lower than tetracycline, precluding the use of tetracycline to predict oxytetracycline susceptibility in this species. Determining potencies of tetracyclines in a physiological medium, such as FBS, is proposed, when the objective is correlation with pharmacokinetic data for dosage determination.     

Effect of transdermally administered fentanyl on the minimum alveolar concentration of isoflurane in cats

OBJECTIVE: To determine the effect of two doses of fentanyl, administered transdermally, on the minimum alveolar concentration (MAC) of isoflurane in cats. STUDY DESIGN: Prospective, randomized study. ANIMALS: Five healthy, spayed, female cats. METHODS: Each cat was studied thrice with at least 2 weeks between each study. In study 1, the baseline isoflurane MAC was determined in triplicate for each cat. In studies 2 and 3, isoflurane MAC was determined 24 hours after placement of either a 25 or 50 microg hour(-1) fentanyl patch. In each MAC study, cats were instrumented to allow collection of arterial blood and measurement of arterial blood pressure. Twenty-four hours prior to studies 2 and 3, a catheter was placed and secured in the jugular vein and either a 25 or 50 microg hour(-1) fentanyl patch was placed in random order on the left thorax. Blood samples for plasma fentanyl determination were collected prior to patch placement and at regular intervals up to 144 hours. After determination of MAC in studies 2 and 3, naloxone was administered as a bolus dose (0.1 mg kg(-1)) followed by an infusion (1 mg kg(-1) hour(-1)) and MAC redetermined. RESULTS: The baseline isoflurane MAC was 1.51 +/- 0.21% (mean +/- SD). Fentanyl (25 and 50 micro g hour(-1)) administered transdermally significantly reduced MAC to 1.25 +/- 0.26 and 1.22 +/- 0.16%, respectively. These MAC reductions were not significantly different from each other. Isoflurane MAC determined during administration of fentanyl 25 micro g hour(-1) and naloxone (1.44 +/- 0.16%) and fentanyl 50 micro g hour(-1) and naloxone (1.51 +/- 0.19%) was not significantly different from baseline MAC (1.51 +/- 0.21%). CONCLUSIONS AND CLINICAL RELEVANCE: Fentanyl patches are placed to provide long-lasting analgesia. In order to be effective postoperatively, fentanyl patches must be placed prior to surgery. Plasma fentanyl concentrations achieved intraoperatively decrease the need for potent inhalant anesthetics in cats.     

In vitro susceptibility of Brachyspira hyodysenteriae to organic acids and essential oil components

The antibacterial potential of organic acids and essential oil components against Brachyspirahyodysenteriae, the causative pathogen of swine dysentery, was evaluated. Minimum inhibitoryconcentrations (MIC) of 15 compounds were determined at pH 7.2 and pH 6.0, using a broth microdilution assay.In addition, possible synergism was determined. MIC values for the three tested strains were similar. Fororganic acids, MIC values at pH 6.0 were lower than at pH 7.2. B. hyodysenteriae was mostsensitive to cinnamaldehyde and lauric acid, with MIC values <1.5 mM. Most antibacterial effects of binarycombinations were additive, however, for thymol and carvacrol, synergism could be observed. Invitro results demonstrate the antibacterial action of certain essential oil components and organicacids against B. hyodysenteriae.     

鸡ND、IB、IBD三联弱毒苗免疫剂量及免疫保护试验研究

本研究采用β-微量血凝抑制试验、琼脂扩散(AGP)试验及强毒攻击保护试验,对研制的ND、IB、IBD三联弱毒疫苗的最小免疫量和免疫保护性进行了测定,结果显示,125羽/mL以下的疫苗都能获得较好保护,且对ND、IB、IBD的保护率分别为100%、90%、70%。     

恩施藤茶乙醇提取物对高温煮熟鱼肉腐败菌的抑制作用研究

以生长菌落数为评价指标,研究恩施藤茶乙醇提取物对高温煮熟鱼肉的防腐效果;采用稀释平板法分离纯化和16S rDNA测序技术鉴定导致高温煮熟鱼肉腐败变质的细菌;运用滤纸片法测试恩施藤茶乙醇提取物对腐败变质细菌的抑菌活性;通过测定恩施藤茶乙醇提取物对腐败变质细菌生长曲线、导电率及生物大分子含量的影响研究其抑菌机理。结果表明:在储藏15 d内,30 mg·mL-1恩施藤茶乙醇提取物能完全抑制高温煮熟鱼肉中细菌生长;分离、鉴定了2株导致高温煮熟鱼肉腐败变质的细菌Bacillus methylotrophicus T-10、Alcaligenes faecalis T-9;恩施藤茶乙醇提取物对这2株腐败菌具有中敏抑菌活性(抑菌圈直径:10~20 mm),其最小抑菌浓度(MIC)分别为16.0 mg·mL-1和20.0 mg·mL-1;恩施藤茶乙醇提取物通过破坏菌体细胞膜的完整性,致使生物大分子物质外溢而发挥抑菌作用。     

DIGITAL POWER SYSTEM STABILIZER ( DPSS )

A digital power system stabilizer ( DPSS ) and its design method are presented in this paper. The mathematical model of a single machine infinite bus power system is obtained using off-line parameter identifications, and on the base of the identified model the control system is synthesized by generalized minimum variance control principles. Through feedback combination of several signals this control system has double functions of damping low frequency oscillation and automatic voltage regulating. In order to avoid static errors the very effective way is to combine discrete generalized minimum variance control with continuous integral control. Besides the proposed control strategy is very simple in structures and very easy to realize. Simulation results under several cases have shown the correctness and effectiveness of the proposed control strategy.     

有风险投资与无风险投资组合的研究

本研究通过引入单位风险的概念，并结合有效边界上的单位风险极小点，给出了各种情况下有风险投资和无风险投资的最优组合方案。     

辽河河口湿地生态环境需水量研究

科学合理地确定辽河河口湿地的适宜与最小生态环境需水量是维持其生态系统健康的重要保障。利用3S技术提取辽河河口湿地覆被信息,将生态环境需水量的计算类型划分为消耗型和非消耗型,建立了适合辽河河口湿地的计算模型,并利用该模型计算了研究区2000、2005和2014年的生态环境需水量以及适宜生态环境需水量与不同降水频率条件下的最小生态环境需水量。结果表明,研究区适宜生态环境需水量为99 554.92×10~4m~3;多年平均降水条件下、75%降水频率下和95%降水频率下对应的最小生态环境需水量分别为20 220.13×10~4m~3、22 362.31×10~4m~3和24 314.98×10~4m~3。     

A systematic review of sevoflurane and isoflurane minimum alveolar concentration in domestic cats

ObjectiveThe purpose of this systematic review is to summarize the results of studies which have determined the minimum alveolar concentration (MAC) of isoflurane and sevoflurane in domestic cats.Study DesignSystematic review.AnimalsCats.Methods usedA comprehensive search of research literature was performed without language restriction. The search utilized the Pubmed, Google Scholar, and CAB Abstracts electronic databases using a combination of free text terms ‘Minimum alveolar concentration’, ‘sevoflurane’, ‘isoflurane’, ‘anesthetic’, ‘cat’, ‘cats’ or ‘feline’. The search was conducted from November 2010 to June 2012.ResultsThe MAC for isoflurane ranged from 1.20 ± 0.13% to 2.22 ± 0.35% and the MAC for sevoflurane ranged from 2.5 ± 0.2% to 3.95 ± 0.33%. The average MAC for isoflurane was 1.71 ± 0.07% and for sevoflurane was 3.08 ± 0.4%.Conclusions &; Clinical RelevanceThe average MAC for isoflurane was 1.71 ± 0.07% and for sevoflurane was 3.08 ± 0.4%. Methodology differed among studies, and particular attention should be paid in the future to appropriate reporting of methods to allow sound conclusions to be made from the results.