注射用盐酸土霉素的细菌内毒素检查

参照<中国兽药典>二○○○年版一部附录细菌内毒素检查法,研究了注射用盐酸土霉素对细菌内毒素检测的干扰情况,确定0.312 5 mg/mL浓度的供试品溶液对检测无干扰作用,建立了注射用盐酸土霉素的细菌内毒素限量检查方法.     

The Pharmacokinetics of a Long-acting Oxytetracycline Formulation in Healthy Dogs and in Dogs Infected with Ehrlichia canis

The pharmacokinetic properties of oxytetracycline were studied following a single injection of a long-acting formulation (20 mg/kg body weight) into the semimembranosus muscle of healthy dogs and of dogs that had been experimentally infected with Ehrlichia canis. The disposition curves of the long-acting oxytetracycline formulation before and after infection were best described by a bi-exponential decline after a first-order absorption. The mean maximum serum concentration (C _max) following infection was significantly lower and the time taken to attain this concentration (t _max) was significantly shorter than that in the healthy dogs. The mean apparent elimination half-life (t _1/2) was significantly increased following infection. The corresponding rate constant () was significantly decreased. The absorption half-life (t _1/2ab) was significantly decreased after infection. The volume of distribution at steady state (V _dss) increased significantly following infection. It was concluded that the pharmacokinetic behaviour of a long-acting oxytetracycline in dogs after intramuscular administration is characterized by a two-compartment model with a slow elimination phase. This could be due to flip-flop kinetics. The febrile reaction in experimental E. canis infection affected some pharmacokinetic parameters of oxytetracycline.     

The Use of Trypanocides and Antibiotics by Maasai Pastoralists

Information was collected on the use of veterinary drugs by Maasai pastoralists in an area of Kenya where tsetse flies and trypanosomosis occur. Three herds of cattle were followed for between 4 and 5 years and records were kept of every veterinary drug treatment given by the livestock owners. Almost all treatments were either with the trypanocides homidium or diminazene, or with oxytetracycline by intramuscular injection. The rate of trypanocide use varied between 0.66 and 1.56 treatments per animal per year, while oxytetracycline use was between 0.20 and 1.00 treatments per animal per year. Farmers were injecting these drugs in the absence of veterinary supervision, obtaining their supplies mainly from local village shops or informal traders. Underdosing with trypanocides appeared to be uncommon and the indications were that farmers generally gave the drugs at dosage rates above the recommended standard dose. Accurate information on the dose rates of oxytetracycline could not be obtained, but it was noted that in most cases farmers gave a single injection rather than a course of treatment. In a proportion of cases, trypanocides and antibiotics were mixed together before injection. The farmers administered the drugs when disease was recognized and were rarely using trypanocides as prophylactics. Although necessity forces the livestock owners to obtain and use these drugs without veterinary supervision, there are concerns with regard to the possibility of drug misuse and the development of drug resistance.     

复方中草药灌注液治疗奶牛子宫内膜炎临床效果观察

目的 研究旨在通过试验观察中草药治疗奶牛子宫内膜炎疗效,以其为临床应用中草药治疗奶牛子宫内膜炎提供参考。方法 将60 头患子宫内膜炎奶牛,随机分成5 组,每组12 头,复方中草药高、中、低剂量组（分别子宫灌注150 mL/头、100 mL/头和50 mL/头）、土霉素组（子宫灌注50 mL/头）和对照组。结果 复方中草药中剂量组和高剂量组的总有效率为75.00%和83.33%,均高于土霉素组的总有效率66.67%;土霉素组在治疗结束后的平均发情天数缩短了14 d,所有复方中草药组的发情天数也缩短了11~19 d;3 个情期内土霉素组受胎率为50.00%,复方中草药组受胎率介于41.67%~66.67%之间。结论 复方中草药对奶牛子宫内膜炎的治疗效果优于土霉素,其中以高剂量组效果最佳。     

Effect of biofilm formation on antimicrobial tolerance of Flavobacterium psychrophilum

Treatment of bacterial fish diseases can be complicated by resistant bacterial biofilms harbouring pathogenic bacteria and causing recurrent exposure of fish to infections. In this study, the effect of biofilm formation on antimicrobial tolerance was examined using three bacterial isolates of the fish pathogen Flavobacterium psychrophilum and two antimicrobial agents, oxytetracycline and flumequine, commonly used in aquaculture. Planktonic and biofilm cells were exposed to a minimum inhibitory concentration (MIC), to a 3 × MIC concentration and to an environmental concentration level of each antimicrobial in 96-well microtitre plates after which growth on agar plates was measured. The type strain NCIMB1947 of F. psychrophilum was further used to study the development of antimicrobial resistance in biofilm cells. The results suggest that at high bacterial densities (>10(7) CFU mL(-1)), biofilm cells of F. psychrophilum are less susceptible to antimicrobial agents. Furthermore, the results imply that biofilm cells of F. psychrophilum may rapidly develop resistance to both oxytetracycline and flumequine if exposed to subinhibitory concentrations of these antimicrobials.     

An assessment of yellow perch, Perca flavescens, stocking contributions in eastern South Dakota lakes

The success and value of yellow perch, Perca flavescens (Mitchill), stocking programmes are largely unknown because of the difficulties in differentiating between naturally recruited and translocated stocks. To determine stocking contributions of yellow perch, fingerlings and adults were collected from natural rearing ponds in south-eastern South Dakota. Prior to stocking, all fish were marked for 6 h in transfer tanks containing 700 mg L⁻¹ oxytetracycline hydrochloride. Six lakes containing yellow perch populations were supplemented at low, medium and high stocking densities of about 25, 135 or 200 fish ha⁻¹, respectively. Yellow perch populations were subsequently sampled with experimental gill nets during late summer; two lakes were resampled with additional gears (electric fishing, trap nets and cloverleaf traps). Yellow perch were processed for routine measurements, and saggital otoliths were removed to determine the origin of the fish. Stock contribution estimates determined from gill-net samples for Island (low), Oak (low), Twin (medium) and Wall (high) lakes were approximately 18, 5, 41, and 38%, respectively. Samples from other gears provided stock contributions of 15 and 10% for Cavour Lake and 41% for Diamond Lake (high density stockings). Although these results showed that supplemental stockings were successful, variability in stock contributions among populations indicates a need for further assessment of variables that may influence the stocking success of yellow perch.     

土霉素固体脂质纳米粒在家兔体内的药代动力学研究

【目的】研究土霉素固体脂质纳米粒在家兔体内的药代动力学特征,以评价其应用效果。【方法】将10只家兔随机分为2组,分别按土霉素剂量20mg/kg腹腔注射土霉素固体脂质纳米粒和土霉素注射液,于设定的时间点采血,用HPLC法测定血浆药物质量浓度,并用DAS3.1.0药动学程序计算药代动力学参数。【结果】土霉素注射液与固体脂质纳米粒的达峰质量浓度(Cmax)分别为(3.676±0.376)和(3.699±0.562)mg/L;吸收平衰期(T1/2Ka)分别为(18.570±0.851)和(27.871±1.767)h;0-∞时段药时曲线下的面积(AUC(0-∞))分别为(83.955±3.720)和(170.150±10.403)mg/(L·h);0-∞时段的平均滞留时间(MRT(0-∞))分别为(36.848±0.268)和(44.672±0.392)h。【结论】土霉素制备成固体脂质纳米粒后,具有明显的缓释作用,血药质量浓度达峰值的时间推迟,同时药物在兔体内平均滞留时间明显长于土霉素注射液,生物利用度得以显著提高。     

土霉素对柑橘黄龙病的防治效果及对柑橘产量和品质的影响

为有效防控柑橘黄龙病，于2017年在佛罗里达大学柑橘研究与教育中心的奥本代尔市柑橘试验场进行田间试验筛选黄龙病的防治药剂及其浓度，测定注射土霉素后叶片中柑橘黄龙病菌亚洲种Cadidatus Liberibacter asiaticus、土霉素、淀粉含量、柑橘产量、出汁率、可溶性固形物含量和酸度，显微镜下观察注射土霉素后淀粉粒的分布。结果表明，浓度为1.6g/株土霉素处理180 d后柑橘叶片中黄龙病菌亚洲种含量减少幅度最大，为91.78%；注射浓度为1.6g/株土霉素后7d，叶片中土霉素含量达142.2 μg/kg，注射后11 d叶片中土霉素含量达到最大，为239.8 μg/kg，注射后45 d叶片中土霉素含量低至99.6 μg/kg以下；注射后7~90d，叶片中黄龙病菌亚洲种含量呈波浪形变化，注射90 d后叶片中黄龙病菌亚洲种含量一直处于增长趋势，叶片中黄龙病菌亚洲种含量总体随着土霉素含量的升高而降低；注射浓度为1.6g/株土霉素后，叶片中淀粉含量大幅度下降，60d时达到最低值，为3.3 μg/mm²，90d时达到峰值，为14.5 μg/mm²；单株产量为16.7 kg，与注射浓度为0.8 g/株土霉素处理差异不显著，但均显著高于其它2个处理；柑橘出汁率、可溶性固形物和酸度均与清水对照差异不显著。表明土霉素可有效抑制黄龙病菌亚洲种，减少柑橘叶片内淀粉含量，增加柑橘产量，但对果实品质未产生显著影响。     

土霉素在斑节对虾体内药代动力学和生物利用度

在自然海水（盐度33）．水温为（28．0±1．0）℃养殖条件下,采用反相高效液相色谱法（RP—HPLC）,研究口灌（100mg／kg）和围心腔注射（20mg／kg）2种给药途径下,土霉素在斑节对虾（Penaeus7YlOylodoYl）体内的药代动力学和生物利用度。围心腔注射和口灌给药下,血药药时曲线均适合采用二室模型拟合。围心腔注射下血药达峰浓度（Cmax）、药时曲线下面积（AUC0-1）、消除半衰期（t,m）分别为（80．71±13．12）mg／L 378．25nag·h·L-1、17．398h;口灌给药下的相应值分别为（21．98±3．32）mg／I。324．52nag·h·L-1、23．372h,土霉素在斑节对虾体内的生物利用度（F）为17．16％。口灌土霉素后,肝胰腺Cmax为（138．655±21．375）μg／g,是血药的6．3倍、肌肉峰浓度的130．2倍,药物在肝胰腺中含量最高;然而。肌肉和肝胰腺中土霉素消除较快,消除半衰期（t1/2x）分别为28．18h和19．311 h。根据我国水产品中药物残留限量规定,水产品中土霉素的最高残留限量（NY5070—2002）为0．1mg／kg,结合本试验研究结果,斑节对虾使用土霉素后的休药期为5d,肌肉可食组织即符合无公害食品标准要求。