液相色谱-串联质谱测定饲料中7种硝基咪唑类药物

采用液相色谱-串联质谱法(LC-MS/MS)测定了饲料中甲硝唑(MNZ)、地美硝唑(DMZ)、洛硝唑(RNZ)、替硝唑(TNZ)、奥硝唑(ONZ)、异丙硝唑(IPZ)和塞克硝唑(SCZ)等7种硝基咪唑类药物。样品用乙酸乙酯提取,正己烷-磷酸溶液反萃取,MCX柱净化,以0.1%乙酸水溶液和乙腈作流动相进行梯度洗脱,电喷雾电离源正离子(ESI+)多反应监测(MRM)模式下检测。方法的检测限和定量限分别为0.03 mg/kg和0.1 mg/kg。添加浓度为0.1、1 mg/kg和10 mg/kg时的平均回收率为72.9%~98.8%,变异系数为4.9%~12.1%。     

动物性食品中硝基咪唑类药物残留检测方法 --高效液相色谱法

农业部于 2 0 0 3年 1月 2 2日发布了 2 3 6号公告 ,发布 1 2个动物性食品中兽药残留检测方法。方法之二 :动物性食品硝基咪唑类药物残留检测方法———高效液相色谱法。动物性食品硝基咪唑类药物残留检测方法———高效液相色谱法1　范围本标准规定了动物性食品中甲硝唑、地美硝唑、洛硝哒唑单个或混合物残留量检测的制样和高效液相色谱测定方法。本标准适用于鸡的肌肉和肝脏组织中甲硝唑、地美硝唑、洛硝哒唑单个或混合物残留量检测。2　规范性引用文件下列文件中的条款通过本标准的引用而成为本标准的条款。凡是注日期的引用文件 ,其随后…     

超高效液相色谱-串联质谱法测定鸡蛋中5种硝基咪唑类兽药残留

本试验基于固相萃取-超高效液相色谱-串联质谱技术，旨在建立鸡蛋中甲硝唑、迪美硝唑、奥硝唑、罗硝唑和替硝唑等5种硝基咪唑类兽药残留的精确定量分析方法。鸡蛋样品采用5%NaCl溶液-乙腈-乙酸乙酯提取，经MCS固相萃取小柱净化，以C18色谱柱进行分离，0.1%甲酸-1 mmol/L甲酸铵水-甲醇为流动相梯度洗脱，在电喷雾ESI离子源正离子模式下，采用多反应监测模式进行定性分析，以内标法进行定量分析。结果表明：方法检出限和定量限分别为0.05～0.1μg/kg和0.2μg/kg，回收率为76.09%～117.73%，相对标准偏差为0.79%～13.13%，精密度较好。5种硝唑咪唑化合物在范围内呈现良好的线性关系，相关系数为0.9931～0.9995。综上，本方法简单、准确、可靠，能满足鸡蛋中5种硝基咪唑类药物残留分析的要求。     

超高效液相色谱-串联质谱法检测饲料中4种硝基咪唑类药物

建立了同时检测饲料中洛硝哒唑、甲硝唑、二甲硝唑、替硝唑4种硝基咪唑类药物的超高效液相色谱-串联质谱法。样品经乙酸乙酯提取,Oasis MCX柱净化,以0.1%甲酸水-乙腈溶液为流动相梯度洗脱进行液相色谱-串联质谱检测。在10、50、100μg/kg的添加浓度下,饲料中各药物的回收率为70.3%～96.0%,相对标准偏差为4.2%～8.7%。检测限为3μg/kg,定量限为10μg/kg。     

鸡肝中硝基咪唑类药物残留的检测

为验证检测方法的有效性,利用超高效液相色谱法对鸡肝中残留的甲硝唑、洛硝哒唑、地美硝唑等三种硝基咪唑类药物进行检测。绘制标准曲线,R2均大于0.99,表明三种硝基咪唑类药物的峰面积与质量浓度呈显著性相关。由此可见,该方法适用于鸡肝中甲硝唑、洛硝哒唑、地美硝唑残留的检测。     

LC/MS法快速检测猪预混合饲料中4种硝基咪唑类药物

试验对猪预混合饲料中4种硝基咪唑类药物(甲硝唑、洛硝哒唑、二甲硝唑和替硝唑)的液相色谱-质谱检测方法(LC/MS)进行了研究。采用0.1mol/l磷酸提取,MCX固相萃取柱净化,LC/MS测定。结果表明:方法平均回收率为86.1%～99.0%,批内变异系数为4.3%～9.4%,批间变异系数为4.9%～10.9%,洛硝哒唑、甲硝唑、替硝唑和二甲硝唑的检测限依次为9.0、3.2、3.9、4.3μg/kg;定量限依次为30.0、10.7、13.0、14.3μg/kg。     

阿苯达唑与硝基咪唑类治疗中美貘贾第鞭毛虫病的临床效果比较

比较了阿苯达唑与硝基咪唑类药物(甲硝唑、奥硝唑)治疗中美貘贾第鞭毛虫病的临床效果。结果显示:硝基咪唑类药物使用后临床症状虽有改善,动物食欲稍有增加,但仍表现腹泻,不能彻底清除病原和痊愈;使用阿苯达唑后临床症状明显改善,食欲恢复正常,粪便成形,病原彻底清除并很快痊愈。表明阿苯达唑较奥硝唑、甲硝唑具有疗效高、疗程短、便于用药、无不良反应的优点,为以后有效治疗动物的贾第虫病提供有效的参考依据。     

鸡肉组织中硝基咪唑类药物及代谢物多残留检测高效液相色谱法研究

建立了鸡肉组织中甲硝唑、洛达硝唑、地美硝唑、替硝唑、塞克硝唑、奥硝唑6种硝基咪唑类药物及地美硝唑代谢产物1-甲基-5-硝基-2-羟甲基咪唑(HMMNI)共7种组分残留检测的高效液相色谱法(HPLC).样品采用乙酸乙酯提取,SCX柱净化;色谱条件:色谱柱为Eclipse Plus C18柱(4.6 mm×150 mm,3.5 μm);流动相为水-乙腈-甲醇,梯度洗脱;柱温为35℃;流速为0.8 mL/min,紫外检测波长为320 nm,外标法定量.结果表明:7种组分在5～60ng/mL范围内,呈良好线性关系,相关系数R2均大于0.998;方法检出限为1 μg/kg;添加浓度分别为2、3、5 μg/kg时,平均回收率为66.6%～101%,批内和批间RSD均小于20%.     

高效液相色谱-质谱法测定猪组织中硝基咪唑类药物残留量

建立了一种高灵敏度和高选择性的检测猪组织中硝基咪唑类药物残留的高效液相色谱-大气压化学电离质谱(APCI)法,可同时进行猪组织中3种硝基咪唑类药物残留的确证分析.本方法检测猪肌肉、肝脏、肾脏和皮下组织中硝基咪唑类药物的检测限为0.5～1μg/kg;空白组织添加硝基咪唑类药物水平为0.5、1、2或4μg/kg时,测得回收率:肌肉为61.1%～85.4%,肝脏为62.3%～80.4%,肾脏为61.6%～82.0%,皮下组织为63.6%～84.1%.     

乌鸡中硝基咪唑类药物检测方法的研究

本研究建立了高效液相色谱串联质谱法测定乌鸡鸡肉中羟基甲硝唑和甲硝唑含量的方法。鸡肉样品经过乙腈水溶液提取,离心取用上清液再经过PRIMEHLB固相萃取柱净化、氮吹、甲醇水溶液定容以及0.22μm水相滤膜过滤,随后用液相色谱法串联质谱法检测硝基咪唑。结果显示:在线性范围0.1μg/L～500μg/L内,硝基咪唑类药物线性关系良好,甲硝唑相关系数为r=0.997,羟基甲硝唑相关系数为r=0.9993。在1.0μg/kg、2.0μg/kg和10μg/kg三个水平添加回收试验条件下,甲硝唑的回收率为80%～109%,相对标准偏差为2.45%～11.0%;羟基甲硝唑的回收率为74.0%～96.6%,相对标准偏差为3.96%～8.33%。可确定的方法检出限甲硝唑为0.35μg/kg,羟基甲硝唑为0.38μg/kg。该方法具有灵敏度高和重现性好的特点,可满足鸡肉中痕量元素的检测。     

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