超高效液相色谱-串联质谱法测定鸡蛋中四环素类、喹诺酮类、磺胺类残留量

建立了超高效液相色谱-串联质谱法，测定了鸡蛋中四环素类、喹诺酮类、磺胺类11种抗生素残留量。采用1%酸化乙腈溶液提取，应用超高效液相色谱-串联质谱仪检测，定量方法采用外标法。鸡蛋中上述11种药物在5～100ng/mL的浓度范围内呈现良好的线性关系，鸡蛋中的检测限为1.0μg/kg，定量限为2.0μg/kg，在1.0～50μg/kg添加浓度范围内的回收率为70.2%～90.2%，批内与批间RSD值均<7.9%。     

鸡蛋和鸡肉中尼卡巴嗪残留检测高效液相色谱 串联质谱法研究

建立了鸡蛋和鸡肉中尼卡巴嗪残留标示物4,4'-二硝基碳酰替苯胺(DNC)检测的高效液相色谱-串联质谱方法(HPLC-MS/MS).液相色谱条件为色谱柱为XBridge C18柱(150 mm×2.1 mm,5 μm),流动相为甲醇 0.1 mol/L的乙酸铵水溶液(75 25,V/V),柱温30 ℃,流速0.2 mL/min,进样量20 μL.质谱条件为电喷雾离子源(ESI-),多反应监测(MRM)方式进行采集;DNC-D8同位素内标法定量.结果表明,DNC在10～500 ng/mL浓度范围内呈现良好的线性关系,R2为0.999 7;鸡蛋和鸡肉中DNC残留检测方法检测限均为0.5 ng/g,定量限均为1 ng/g;鸡蛋中从2、5和10 ng/g三个添加浓度检测结果可以看出,方法平均回收率为95.9%～102.2%,批内RSD为0.9%～4.4%,批间RSD为0.3%～2.1%.鸡肉组织从100、200和300 ng/g三个添加浓度检测结果可以看出,方法平均回收率为94.0%～103.3%,批内RSD为2.0%～6.3%,批间RSD为3.1%～5.2%.     

超高效液相色谱-串联质谱法测定鸡蛋中沙拉沙星残留的研究

建立了鸡蛋中沙拉沙星残留检测的液相色谱-串联质谱法。样品经1 mol/L磷酸和乙腈提取后,饱和正己烷除脂净化,以0.1%甲酸溶液和乙腈为流动相,液相色谱-串联质谱法测定,内标法定量。试验结果表明：沙拉沙星在1～25 ng/mL浓度范围内线性关系良好,相关系数r大于0.999。沙拉沙星在鸡全蛋及其蛋清、蛋黄中的检测限均为0.5μg/kg,定量限为1μg/kg。沙拉沙星在1、10、20μg/kg浓度添加水平内的平均回收率范围为97.0%～105.4%,批内、批间相对标准偏差在1.3%～10.3%范围之间。本方法适用于鸡全蛋及其蛋清、蛋黄中沙拉沙星残留量的测定。     

超高效液相色谱-串联质谱法测定猪牛组织中甲基盐霉素残留量

建立超高效液相色谱-串联质谱法测定猪牛组织中甲基盐霉素残留量。猪、牛组织中残留的甲基盐霉素,经乙腈溶液提取,硅胶固相萃取柱净化,超高效液相色谱-串联质谱法测定,外标法定量。甲基盐霉素在5 ng/mL～250 ng/mL的浓度范围内呈现良好的线性关系,甲基盐霉素在猪、牛肌肉、肝脏、肾脏、脂肪中的检测限均为2.5μg/kg,定量限均为5.0μg/kg,猪牛肌肉、肝脏、肾脏、脂肪中5.0 ng/g～100 ng/g添加浓度范围内的回收率均值为71.9%～88.4%,批内批间RSD值均<15%。     

鸡蛋中硝基呋喃类代谢物残留的UPLC-MS/MS检测方法研究

为建立鸡蛋中硝基呋喃类代谢物(AOZ、AMOZ、AHD和SEM)残留检测的超高效液相色谱-串联质谱方法(UPLC-MS/MS),采用内标法定量,样品在酸性条件下衍生化后,弱碱性条件下用乙酸乙酯提取后,用正己烷去除脂肪,高速离心去除蛋白质等杂质,上机测试。液相色谱条件:色谱柱为BEH C18(50 mm×2.1 mm,1.7μm),流动相为甲醇+10 mmol/L乙酸铵水溶液,梯度洗脱,流速为0.3m L/min,柱温为30℃,进样量为10μL。质谱条件:电喷雾离子源(ESI+),多反应监测(MRM)方式进行采集。结果表明:硝基呋喃类代谢物在0.5~20 ng/mL浓度范围内均呈现良好的线性关系,相关系数(R2)均大于0.990。鸡蛋中四种代谢物的检测限均为0.25 ng/g,定量限均为0.5 ng/g。在0.5、1和5 ng/g三个添加浓度平均回收率为79.1%~109.4%,批内和批间RSD均小于20%。该方法具有简便快捷、灵敏度高、定性准确等特点。     

液相色谱-串联质谱法测定猪肌肉中硝基呋喃类代谢物的残留量

本文应用液相色谱-串联质谱法测定猪肉组织中硝基呋喃类代谢物。猪肌肉组织中硝基呋喃类代谢物经衍生化、提取后,采用电喷雾离子源,正离子检测方式进行分析。在0.5～20ng/ml浓度范围内,4种硝基呋喃类代谢物均呈线性,相关系数r〉0.995,在空白猪肉中添加浓度2.5μg/kg范围内的回收率均在80%～100%之间,批内批间RSD值均〈20%,实验结果完全符合国家规定的兽药残留实验技术规范的要求。     

用超高效液相色谱-串联质谱检测动物源性食品中头孢喹肟残留

建立了动物源性食品中头孢喹肟残留量检测的超高效液相色谱-串联质谱法。样品经乙腈水溶液提取后,用C18固相萃取柱净化、浓缩。头孢喹肟残留量在10～500μg/L浓度范围内线性关系良好,r=0.9996。方法检测限为1 ng/g,定量限为5 ng/g。猪肌肉在5～100 ng/g空白添加浓度范围内平均回收率为57.7%～69.4%,RSD为6.68%～13.41%,猪肝在5～100 ng/g空白添加浓度范围内平均回收率为50.6%～58.6%,RSD为5.13%～12.42%,牛奶在5～40 ng/g空白添加浓度范围内中平均回收率为59.2%～65.3%,RSD为6.12%～13.26%。     

羊组织中三氯苯唑及代谢物残留量检测方法研究

建立了一种可同时检测羊组织中三氯苯达唑及其代谢物三氯苯达唑酮残留的高效液相色谱检测方法。结果表明三氯苯达唑、三氯苯达唑酮浓度在20～600 ng/mL范围时与峰面积呈良好的线性关系,R2均大于0.999 9,方法的定量限为30μg/kg。三氯苯达唑、三氯苯达唑酮在30～300μg/kg的浓度添加水平上,其回收率在60%～100%,批内、批间的相对标准偏差均小于15%。     

鸡蛋中硝基呋喃类代谢物残留检测UPLC-MS/MS法研究

建立了鸡蛋中硝基呋喃类代谢物（AOZ、AMOZ、AHD和SEM）残留检测的超高效液相色谱-串联质谱方法（UPLC-MS/MS）。样品在酸性条件下衍生化后,弱碱性条件下用乙酸乙酯提取后,用正己烷去除脂肪,高速离心去除蛋白质等杂质,上机测试。液相色谱条件：色谱柱为BEH C18（50×2.1mm,1.7μm）,流动相为甲醇+10mmol/L乙酸铵水溶液,梯度洗脱,流速为0.3 mL/min,柱温为30 ℃,进样量为10 μL。质谱条件：电喷雾离子源（ESI+）,多反应监测（MRM）方式进行采集。结果表明：硝基呋喃类代谢物在0.5~20 ng/mL浓度范围内均呈现良好的线性关系,相关系数（R2）均大于0.990;鸡蛋中四种代谢物的检测限均为0.25ng/g,定量限均为0.5ng/g。在0.5、1和5 ng/g三个添加浓度平均回收率为79.1％~109.4％,批内和批间RSD均小于20%。该方法具有简便快捷、灵敏度高、定性准确等特点。     

液相色谱-串联质谱法检测鸡肌肉组织中硝基呋喃类代谢物的研究

建立了一种专属、灵敏的液相色谱-串联质谱法,同时检测鸡肌肉组织中硝基呋喃类代谢物：呋喃唑酮代谢物AOZ、呋喃它酮代谢物AMOZ,呋喃妥因代谢物AHD和呋喃西林代谢物SEM.鸡肌肉组织中硝基呋喃类代谢物经衍生化、提取后,采用电喷雾离子源,正离子检测方式进行分析.在0.5～20 ng/mL浓度范围内,4种硝基呋喃类代谢物均呈线性,相关系数r＞0.99.在0.5、1和2 μg/kg 3种添加浓度,AOZ、AMOZ、AHD和SEM相应的平均回收率在80%～120%,RSD＜16%.4种硝基呋喃类代谢物的检测限均可达到0.25 μg/kg.该方法专属性强、灵敏度高,适用于鸡肌肉组织中硝基呋喃类代谢物的检测.     

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