盐酸多西环素片在羔羊体内残留消除规律及休药期分析

旨在确定盐酸多西环素片按照给药说明给药后在羔羊体内的残留消除规律及休药期。将盐酸多西环素片根据体重以5 mg·kg^-1内服给药,间隔24 h,连续给药5次。在最后1次给药后,分别在第0（12小时）、1、2、3、5、7和9天时间点采集羔羊脂肪、肌肉、肝和肾,采用建立并验证的HPLC-VWD方法测定组织中多西环素的含量。结果显示：方法学考察结果表明,在50~5 000 ng·mL^-1添加的线性方程和相关系数为y=0.044x-0.414,R²=0.999。试验结果表明,多西环素在羔羊组织中代谢快速,最后1次给药后第9天,在肌肉、肝、肾和脂肪中均未检测到多西环素。本试验以5 mg·kg^-1体重内服给予羔羊盐酸多西环素片后,根据欧洲药品评估机构法规《EMEA/CVMP/036/95》,建议盐酸多西环素片在羔羊组织中的休药期为2 d。     

盐酸多西环素注射液在猪体内残留消除规律研究

为研究自制盐酸多西环素注射液在猪体内的残留消除规律,以10 mg/kg剂量给健康猪肌内注射盐酸多西环素注射液,每日1次给药,连续三次。在最后一次给药后7、14、21、28和35 d时间点采集肌肉、肝脏、肾脏、脂肪和注射部位肌肉,用UPLC-MS/MS法测定组织中多西环素残留量。结果表明,给药35 d后,肌肉、肝脏、肾脏、脂肪和注射部位肌肉中的多西环素残留量分别为18、24、69、10、59μg/kg,均低于最高残留限量。用WT1.4软件计算休药期,盐酸多西环素注射液在猪肌肉、肝脏、肾脏、脂肪和注射部位肌肉中的休药期分别为33.9、23.8、24.8、0和36.9 d,为保证兽药安全使用、消费者身体健康与食品安全,建议盐酸多西环素注射液在猪的休药期为42 d。     

盐酸多西环素在猪体内的药物动力学及其残留

试验建立了反相高效液相色谱(RT-HPLC)法测定盐酸多西环素的浓度,探讨了盐酸多西环素在猪体内的药物动力学和残留特征。结果表明,盐酸多西环素以2.5mg/kg单剂量肌内注射给猪(n=6),药物动力学模型符合有吸收一室模型,药物动力学参数:吸收半衰期(t1/2ka)、消除半衰期(t1/2ke)为(0.400±0.312)h、(9.530±0.956)h,药时曲线下面积(AUC)为(44.414±4.123)mg·h·L-1,最大血药浓度(Cmax)为(2.811±0.136)mg/L,达峰时间(Tp)为(1.910±0.213)h。另外,以相同剂量肌内注射给猪(n=6),每天1次,连续给药4d后,在不同时间测定盐酸多西环素在猪的肌肉、肝脏、肾脏、皮肤和脂肪中的残留量。在给药后16d,盐酸多西环素在各组织均能检测到,且残留均低于残留限量。盐酸多西环素注射液在猪体内消除缓慢,残留期较长,建议休药期不低于16d。     

长效盐酸多西环素注射液在猪体内残留的消除规律

在常规饲养条件下,对35头健康成年猪按10 mg/kg体质量的剂量肌肉注射10%长效盐酸多西环素注射液,给药2次,给药间隔时间为48 h。第2次给药后12 h及2、5、9、14、192、5 d分别屠宰5头猪,分别采取每头猪的肌肉、肝脏、肾脏、皮肤+脂肪和注射位点肌肉等5种组织,用高效液相色谱法进行残留量测定。结果表明:在第2次给药后19 d,多西环素在各组织均能检测到,且残留均低于残留限量。多西环素残留浓度大小顺序:注射部位(肾脏(肝脏(皮脂(肌肉。采用WT1.4软件制定的统计方法来处理猪组织中药物浓度-时间数据,以制定休药期。     

盐酸多西环素注射液在猪体内药效-药代动力学研究

为研究自制盐酸多西环素注射液在猪体内的药代动力学-药效学,对10头健康猪单次肌内注射盐酸多西环素注射液,采用UPLC法测定血浆中药物浓度,利用药代动力学软件WinNonlin进行数据处理。结果显示,主要药代动力学参数：消除半衰期t1/2为（31．3±9．2）h,达峰时间Tmax为（0．80±0．7）h,峰浓度Cmax为（4132±2475）μg/L,药时曲线下面积AUC为（88378±88095）（μg／L）·h,平均滞留时间MRT为（20．5±2．5）h;PK／PD参数T〉MIC为24h,AUC／MIC〉50。试验表明该制剂以10mg／kg剂量肌内注射,给药间隔两天一次为宜。     

盐酸多西环素缓释注射液在猪体内的药物动力学

健康猪6头,体质量(17.85±1.3)kg,按拉丁方设计进行单剂量静注、肌注盐酸多西环素注射液(普通制剂)和肌注盐酸多西环素缓释注射液,注射剂量按多西环素计均为20 mg/kg,比较盐酸多西环素缓释注射液和盐酸多西环素注射液在猪体内的药动学特征和生物利用度.用高效液相色谱法测定其血药浓度,试验所得的血药浓度-时间数据采用非房室模型统计矩原理分析处理.猪静注盐酸多西环素注射液的主要药物动力学参数为AUC(108.15±13,25)mg·h·L-1,MRT(5.56±1.08)h,CI(0.19±0.02)L·h-1·kg-1,Vd(ss)(1.04±0.09)L·kg-1,t1/2(4.07±0.65)h.猪肌注盐酸多西环素注射液和盐酸多西环素缓释注射液的主要药物动力学参数分别为MRT(15.18±2.13)h和(22.25±3.49)h;Tmax(1.135±0.44)h和(2.0±0.63)h;Cmax(3.32±0.33)mg·L-1和(3.10±0.29)mg·L-1;AUC(38.91±4.35)mg·h·L-1和(61.72±10.16)mg·h·L-1;F(36.66±7.88)%和(57.66±10.75)%.比较盐酸多西环素注射液和盐酸多西环素缓释注射液的主要药动学参数,除了Cmax以外,MRT、Tmax、AUC、F等主要参数均有显著的统计学意义(P＜0.05).这表明盐酸多西环素缓释注射液肌注后吸收缓慢.消除半衰期延长,临床用药48 h给药1次仍能维持对常见病原菌的有效血药浓度.     

两种盐酸多西环素注射液在猪体内的药代动力学研究

研究制备了两种稳定的20％盐酸多西环素注射液,按10 mg/kg的剂量分别给猪肌肉注射,观察两个制剂在猪体内单剂量肌注的药代动力学特征.结果表明,多西环素在猪体内的药物动力学特征均符合一级吸收二室开放模型,其主要的药物代谢动力学参数:消除半衰期(T1/2β)分别为(3.246±1.04)和(9.631±1.12)h,药时曲线下面积(AUC)为(10.462±0.28)和(17.525±0.14)(μg/mL)*h,达峰时间(Tpeak)及达峰浓度(Cmax)分别为(1.427±0.16)h、(1.465±0.20) μg/mL和(1.694±0.15)h、(1.058±0.09) μg/mL.其中制剂一的血药浓度在给药2h后迅速降低,为普通注射液;与制剂一相比,制剂二能够缓慢释放药物,为长效缓释盐酸多西环素注射液.     

牛奶中多西环素残留消除及最大残留限量

为制定牛奶中多西环素最大残留限量标准,首先开展盐酸多西环素子宫注入剂在牛奶中的残留消除试验,盐酸多西环素子宫注入剂经子宫给药1次,给药前及停药后6,12,24,48,72,96,120,144和168 h共10个时间点采集牛奶,采用液相色谱-串联质谱测定多西环素残留量。然后在查阅国际食品法典委员会、欧洲药品管理局和我国制定动物性食品中多西环素最大残留限量研究报道基础上,制定牛奶中多西环素最大残留限量标准。结果表明,停药后168 h,牛奶中多西环素的残留量均低于10μg/kg。多西环素每日允许摄入量为0～3μg/kg,建议参照欧盟动物性食品中多西环素最大残留限量制定方法,将每日允许摄入量按比例分配到全部组织+奶,推荐牛奶中多西环素的最大残留限量为10μg/kg,盐酸多西环素子宫注入剂在牛奶中弃奶期为9 d。     

恩诺沙星可溶性粉在北京油鸡体内残留消除规律研究

为研究恩诺沙星可溶性粉在北京油鸡体内的残留消除规律，以确定休药期，试验采用推荐剂量（75 mg/L）和2倍推荐剂量（150 mg/L）恩诺沙星自由饮水方式连续对北京油鸡给药5 d，在最后一次给药后0（停药后4 h）、1、3、5、7、9、12和15 d，采集北京油鸡肝脏、肾脏、肌肉和脂肪，采用高效液相色谱串联质谱法测定各组织中的恩诺沙星及其代谢物环丙沙星的残留量，并用WT1.4软件计算休药期。结果显示，推荐剂量5%恩诺沙星可溶性粉在北京油鸡各组织的休药期分别为肝脏7.1 d、肌肉3.8 d、肾脏5.2 d、脂肪4.4 d,2倍推荐剂量的休药期分别为肝脏9.6 d、肌肉4.2 d、肾脏6.4 d和脂肪8.4 d。结果表明，恩诺沙星在北京油鸡的休药期可设置为8 d。     

双波长紫外分光光度法测定酒石酸泰乐菌素-盐酸多西环素可溶性粉的含量

建立了双波长紫外分光光度法同时测定酒石酸泰乐菌素-盐酸多西环素可溶性粉中酒石酸泰乐菌素和盐酸多西环素含量的检测方法。结果显示，吸收度与浓度呈良好线性关系。酒石酸泰乐菌素的平均回收率为99．90％，RSD为0．42％n=5）；盐酸多西环素的平均回收率为100．07％，RSD为0．74％（n=5）。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -