替米考星含量测定方法的改进研究

建立了高效液相色谱法测定替米考星原料及其制剂的中替米考星的含量。采用C18色谱柱（4.6mm×250mm，5μm），以10%三氟乙酸-乙腈（65-35）为流动相，流速1.0 mL/min，进样量10 μL，检测波长为280 nm，柱温30℃。结果表明，当替米考星浓度为0.01～2.0 mg/mL时，替米考星顺式峰和反式峰面积和与浓度线性关系良好（R2=0.9998），无杂质干扰，重复性、稳定性和精密度的相对标准偏差＜0.8%，检出限为0.8 μg/mL，替米考星顺式峰和反式峰的分离度符合规定，顺-8-差向异构体能够实现良好分离。该方法操作简便，准确度高，重复性好，提高了替米考星及其制剂质量控制的检测效率，为其质量标准的改进提供了依据。     

超高效液相色谱-串联质谱法同时测定饲料中6种多肽类抗生素

本研究旨在建立超高效液相色谱-串联质谱法同时测定饲料中6种多肽类抗生素的分析方法。样品用0.1 mol/L盐酸水溶液/乙腈（3：7，V/V）作为提取液提取，经PRiME HLB固相萃取柱净化，在电喷雾电离正离子模式下使用超高效液相色谱-串联质谱仪进行测定，外标法定量。结果表明：恩拉霉素A和B、杆菌肽A和B在质量浓度为5 ~ 200 μg/L内，维吉尼亚霉素M1和S1在质量浓度为2.5 ~ 100 μg/L内线性关系良好，相关系数（r2）为0.9985 ~ 0.9991。6种多肽类抗生素在添加浓度0.025 ~ 1.0 mg/kg内，平均回收率为83.2% ~ 112.1%，相对标准偏差（RSDs）小于7.8%，方法的定量限为0.025 ~ 0.05 mg/kg。该方法快速简便、准确可信、灵敏度高，适合饲料中多肽类抗生素的检测。 [关键词] 超高效液相色谱-串联质谱法|PRiME HLB固相萃取柱|饲料|多肽类抗生素     

超高效液相色谱-串联质谱法同时测定饲料中的喹诺酮类和四环素类药物含量

为建立同时测定饲料中5种喹诺酮类和4种四环素类药物含量的超高效液相色谱-串联质谱（UPLC/MS/MS）分析方法,本实验采用1%甲酸甲醇溶液作为样品的提取溶液,经HLB固相萃取柱净化后上机测定。在正离子模式下通过两对离子对进行定性和定量分析,基质匹配标准溶液外标法校准。结果显示：各药物浓度在2.5 ～ 50 μg/L内线性关系良好,相关系数r均大于0.995|空白饲料添加浓度为0.05、0.1、0.25 mg/kg时,回收率为74.7% ～ 93.2%|批内、批间相对偏差（RSD）均小于15%|本方法对饲料中喹诺酮类和四环素类药物的定量限为0.05 mg/kg（S/N＞10）,检测限为0.025 mg/kg（S/N＞3）。 [关键词] 喹诺酮类|四环素类|饲料|超高效液相色谱-串联质谱     

液相色谱技术在饲料中抗菌肽分离纯化和含量测定的应用研究

文章旨在分析纯化饲料添加剂中的抗菌肽，为抗菌肽的含量测定及样品检测提供了参考依据。本研究采用过滤膜超滤浓缩，采用固相萃取柱进行洗脱和分离，用过滤膜进行过滤，用高效液相色谱仪进行分离纯化，优化色谱条件，并对不同类型的饲料中抗菌肽的含量进行测定，流动相为甲醇，实验将流速设置为0.75 mL/min，甲醇的体积比为10%，柱温度为31℃，检测波长为526 nm，进样量为10 ul，而后用高效液相色谱仪测定饲料中抗菌肽含量。结果显示：该方法分离纯化获得的抗菌肽蛋白活性较强。该方法检测饲料中抗菌肽的保留时间为7.25 min，呈现单峰，峰值较好，在误差范围呈现线性关系，方法操作简单、快速、安全环保、灵敏度高，应用范围广泛。液体动物饲料添加剂的抗菌肽测定值为2.45 mg/kg，水产动物饲料和家禽饲动物料的抗菌肽测定值分别为3.14 mg/kg和2.56 mg/kg。因此，本实验建立了高效液相测定法有利于饲料中抗菌肽的纯化和饲料中抗菌肽的测定。 [关键词]抗菌肽|高效液相色谱|分离纯化|含量测定     

高效液相色谱法测定饲料中苯丙酸诺龙含量的研究

本实验建立了测定饲料中苯丙酸诺龙含量的高效液相色谱检测方法。5.0 g饲料样品经叔丁基甲醚提取后,旋转蒸发至干,5 mL甲醇复溶,冷冻净化除脂后进行HPLC检测分析。以乙腈-水为流动相,采用反相高效液相色谱-紫外检测法进行测定,检测波长为241 nm,流速为1.0 mL/min。结果表明:此条件下,苯丙酸诺龙的线性范围是0.1~25.0 mg/L,回收率为92.3%~101%,方法的检测限为0.1 mg/kg,定量限为0.5 mg/kg。     

多重杂质吸附结合液相色谱串联质谱测定宠物饲料中牛磺酸

本研究采用多重杂质吸附净化技术结合液相色谱-串联质谱仪（LC-MS/MS）建立了宠物饲料中牛磺酸含量的检测方法。宠物饲料样品经0.5 mol/L盐酸溶液提取，使用多重杂质吸附技术富集净化后，上LC-MS/MS分析测定。结果表明：牛磺酸在宠物饲料中的检测回收率＞85%，变异系数＜10%，检出限为5 mg/kg。该方法适用于宠物饲料中牛磺酸含量的测定。 [关键词] 牛磺酸|液相色谱-串联质谱|多重杂质吸附|宠物饲料     

同位素内标-液质联用法测定鸡可食性组织中替米考星残留量

建立了鸡四种可食性组织中替米考星的液相色谱串联质谱内标法。样品经磷酸二氢钾缓冲液和乙腈提取后,C18固相萃取柱净化,以0.1%甲酸乙腈溶液和0.1%甲酸水为流动相,液相色谱串联质谱法测定,内标法定量。试验结果表明：鸡四种可食性组织中替米考星在1 μg/kg~100 μg/kg的浓度范围内呈线性关系,相关系数r大于0.99;替米考星在鸡四种可食性组织中的检测限为0.5 μg/kg,定量限为1 μg/kg;四种组织中替米考星添加浓度为1 μg/kg~4800 μg/kg时,批间平均回收率为94.6%~100.9%,批内、批间变异系数在1.11%-5.06%范围之间。本方法适用于鸡四种可食性组织中替米考星含量的测定。     

替米考星预混剂在猪组织中残留消除规律的研究

为了研究替米考星预混剂在猪体内残留消除规律,试验采用400 mg/kg替米考星预混剂饲喂猪,饲喂过程中及饲喂后不同时间取猪肌肉、肝脏和肾脏,用高效液相色谱法检测替米考星浓度。结果表明:饲喂期间,猪肌肉、肝脏、肾脏中替米考星含量在0.1~1.5μg/g之间,停药14天猪肌肉、肝脏和肾脏中替米考星含量已经降到最高残留限量以下。     

高效液相色谱法测定饲料中盐酸赛庚啶和盐酸可乐定含量

本实验建立了高效液相色谱法测定饲料中盐酸赛庚啶和盐酸可乐定含量的方法。取2 g样品以0.1%盐酸-乙腈沉淀蛋白,8000 r/min高速离心3 min后合并上清液,50℃减压旋转蒸发至干。5 mL 0.1%盐酸-乙腈(90∶10,V/V)溶液溶解后通过混合型阳离子交换柱净化,收集洗脱液于50℃减压旋转蒸发至干,用1 mL 0.1%盐酸-乙腈(90∶10,V/V)溶液溶解后,过0.22μm尼龙过滤膜,上机测定。液相色谱条件为:流动相A为0.1%HCl(pH=2.0),流动相B为乙腈,进行梯度洗脱,色谱柱为十八烷基硅烷键合相,柱温30℃,流速1.0 mL/min,检测器为二极管阵列检测器,检测波长为210 nm。实验结果表明,该方法在1~100 mg/kg线性关系良好(r0.999),在预混合饲料、浓缩饲料、配合饲料中添加量为1、10、100 mg/kg时方法的准确性(回收率70%)和重现性(RSD10%)好,可用于饲料中盐酸赛庚啶和盐酸可乐定含量的检测。     

高效液相色谱法测定饲料中替米考星的含量

本试验介绍了用高效液相色谱法测定饲料中替米考星含量的方法。采用Phenyl色谱柱分离,梯度洗脱,在紫外280nm处检测,外标法定量。结果表明,该方法回收率为94.2%～104.6%,定量限(LOQ)为2mg/kg。     

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.     

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

Tropical Animal Health and Production -     

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.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

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