高效液相色谱法检测多种动物组织中氟喹诺酮类药物残留量的研究

建立了猪、牛、羊、鸡、兔的肌肉、脂肪、肝脏和肾脏四种组织中环丙沙星、达氟沙星、恩诺沙星、沙拉沙星和二氟沙星残留量检测的高效液相色谱法。试样经磷酸盐溶液提取,C18固相萃取柱浓缩净化后,用高效液相色谱分析,荧光检测器检测,外标法定量。5种药物在0.1～100μg/L浓度范围内线性关系良好。环丙沙星、恩诺沙星、沙拉沙星和二氟沙星在五种动物肌肉、脂肪组织中的定量限为5μg/kg,在肝脏、肾脏组织中的定量限为10μg/kg;达氟沙星在肌肉、脂肪组织中的定量限为1μg/kg,在肝脏、肾脏组织中的定量限为2μg/kg。在指定的三个浓度添加水平下,5种药物在各组织中的平均回收率为62%～103%;批内变异系数为0.30%～18%,批间变异系数为1.0%～17%。该方法操作简单,准确度和精密度好,动物品种及动物组织覆盖范围广,可以很好地满足实际检测工作的需要。     

猪肉及猪肝中四环素类药物残留量测定的高效液相色谱法

采用高效液相色谱法建立了猪肉及猪肝中土霉素、四环素、金霉素、多西环素残留量的检测方法。试样中的四环素类药物经Na2EDTA-Mcllvaine缓冲溶液提取,硫酸和钨酸钠溶液沉淀蛋白,HLB及LCX固相萃取柱净化,高效液相色谱法测定。以0.01 mol/L三氟乙酸-乙腈为流动相,梯度洗脱,检测波长为340 nm。结果显示：四种四环素类药物在0.05~5 μg/mL质量浓度范围内呈良好的线性关系,决定系数大于0.999。本方法在猪肉中的检测限为20 μg/kg,定量限为50 μg/kg;在猪肝中的检测限为50 μg/kg,定量限为100 μg/kg。在空白猪肉组织中添加50~200 μg/kg浓度,平均回收率为62.8%~114.4%,日内相对标准偏差为0.5%~6.6%,日间相对标准偏差为21%~5.4%;在空白猪肝组织中添加100~600 μg/kg浓度,平均回收率为602%~111.9%,日内相对标准偏差为0.3%~3.1%,日间相对标准偏差为1.1%~3.5%。该方法各项技术指标均能满足残留检测要求,且重现性良好,适用于猪肉及猪肝中四环素类药物残留量的测定。     

超高效液相色谱—串联质谱法检测鸡组织中黏杆菌素残留

将鸡组织样品经酸性乙腈溶液提取,正己烷去脂后C18固相萃取柱净化,样品浓缩后在XevoTM TQ-S串联四极杆质谱仪多反映监测(MRM)下测定.黏杆菌素标准曲线在10 μg/kg到1000 μg/kg浓度范围内线性良好(r＞0.997).在0.02μg/g、0.10 μg/g、1.00 μg/g添加水平下,黏杆菌素在鸡组织(肾脏、肝脏、肌肉和脑)中添加回收率在83.43％～98.15％之间,日内和日间变异系数(RSD)均小于10％;黏杆菌素在鸡组织中的定量限为20 μg/kg,最低检测限为10 μg/kg.结果表明,建立了一种灵敏、可靠的检查鸡组织中黏杆菌素药物残留的超高效液相色谱-串联质谱分析方法.     

鸡蛋中四环素类药物残留量测定的高效液相色谱法研究

建立了鸡蛋中土霉素、四环素、金霉素、多西环素残留量测定的高效液相色谱法。样品经弱酸性缓冲液提取后,HLB固相萃取柱净化后,反相液相色谱分离测定,本方法的检出限为10μg／kg,定量限为50μg／kg。四种四环素类药物在50～1000ng／mL范围内呈线性相关。在100～400ng／g添加浓度范围内,平均回收率为60％～110％,批内变异系数在3．2％～13．7％之间（n=5）,批间变异系数在0．9％-5．3％之间（n=4）。结果表明,该法简单、灵敏、特异性强,适用于鸡蛋中土霉素、四环素、金霉素、多西环素残留量的测定。     

基于PRiME HLB前处理技术的鸡蛋中四环素类药物的快速筛选方法研究

使用新型固相萃取小柱PRiC_1MEC_1 HLB处理鸡蛋样品,建立了一种鸡蛋中四种四环素类药物的简单、快速的筛选分析方法。鸡蛋样品经Na_2EDTA-Mcllvaine缓冲液提取,乙腈沉淀蛋白,PRiC_1MEC_1 HLB固相萃取柱净化,浓缩富集后,采用液相色谱法检测,外标法定量。PRiC_1MEC_1 HLB固相萃取法是简单的通过式净化处理方法,样品净化过程简单、快速、高效。方法最低检出限为50μg/kg,定量限为100μg/kg,土霉素、四环素、金霉素、多西环素4种四环素类药物在50~5000C_1ng/mC_1L范围内呈现良好线性,回收率满足分析筛选的要求。该方法可以有效起到快速筛选鸡蛋中四环素类药物残留的作用,具有较广的应用性。     

牛可食性组织中加米霉素残留量的液相色谱-串联质谱检测方法的研究

本试验建立了牛可食性组织中加米霉素残留量检测的制样和高效液相色谱-串联质谱检测方法,适用于牛组织中加米霉素残留量的测定。牛组织(牛的肌肉、肝脏、肾脏和脂肪)经绞碎、均质后,样品经0. 1 mol/L磷酸二氢钾缓冲液提取,Oasis HLB固相萃取柱净化,高效液相色谱-串联质谱法检测,内标法定量。该方法特异性好,空白样品无干扰。该方法的检测限为1μg/kg,定量限为2μg/kg,基质匹配标准曲线范围为5μg/L～500μg/L,相关系数 0. 99;牛肌肉和肾脏组织在2、50、100、200μg/kg四个添加浓度的平均回收率为93. 56%～103. 31%,批内变异系数≤8. 67%,批间变异系数≤6. 70%;牛肝脏组织在2、100、200、400μg/kg四个添加浓度的平均回收率为94. 37%～102. 52%,批内变异系数≤5. 70%,批间变异系数≤4. 61%;牛脂肪组织在2、10、20、40μg/kg四个添加浓度的平均回收率为100. 95%～105. 58%,批内变异系数≤5. 89%,批间变异系数≤4. 52%。     

猪鸡组织中左旋咪唑残留的HPLC检测方法研究

建立了猪、鸡组织中左旋咪唑残留检测的高效液相色谱法。组织试样在碱性条件下先用乙酸乙酯提取,然后用0.1 mol/L盐酸反萃取,萃取的样液用混合型阳离子固相萃取小柱净化,采用C18(5μm,250 mm×4.6 mm i.d.)色谱柱,用高效液相色谱仪(带紫外检测器)在220 nm波长处测定,外标法定量。在此条件下,左旋咪唑的保留时间为12～14 min。左旋咪唑浓度在10～1 000μg/L时,与峰面积呈良好的线性关系,线性方程为y=196.37x+81.599(r=0.999 9)。结果表明,左旋咪唑在在猪、鸡的肌肉、脂肪和肾脏中的检测限为2μg/kg,定量限为5μg/kg;在猪、鸡的肝脏中的检测限为2μg/kg,定量限为10μg/kg。在添加不同浓度水平测定下,平均回收率在70%～110%,批内变异系数在10%以内,批间变异系数在15%以内。     

UPLC-MS/MS法检测禽蛋中四环素类药物及其代谢物的残留量

研究建立了禽蛋中四环素类药物及其代谢物残留量检测的UPLC-MS/MS法。将待测物用Na_2EDTA-Mcllvaine缓冲液提取两次,水饱和的正己烷脱脂,过Oasis PRiME HLB固相萃取小柱,用液相色谱-串联质谱仪测定,外标法定量。结果表明,6种四环素类药物在2.0~100.0 ng/mL浓度范围内呈现良好线性,回收率在72.8%~96.4%之间,RSD小于15%,方法的检出限为0.5μg/kg,定量限为1.0μg/kg。     

鸡皮脂和肾脏中替米考星残留HPLC检测方法的建立

本试验旨在建立鸡皮脂和肾脏组织中替米考星残留量的HPLC测定方法。皮脂和肾脏组织中残留的替米考星用乙腈提取、MCX固相萃取柱净化,采用高效液相色谱-紫外检测法测定。皮脂组织和肾脏组织中替米考星检测限分别为20μg/kg和30μg/kg,定量限分别为35μg/kg和50μg/kg。空白皮脂组织添加替米考星在35～150μg/kg浓度水平,回收率在75%～98%之间,批内与批间变异系数均小于10%;空白肾脏组织添加替米考星在50～500μg/kg浓度水平,回收率在71%～97%之间,批内变异系数小于11%,批间变异系数小于10%。本试验建立的方法快速、准确、灵敏,适用于鸡皮脂和肾脏组织中替米考星残留量的检测。     

妥曲珠利在肉鸡组织中残留的研究

用高效液相色谱法(HPLC)检测肉鸡肌肉、肝脏和肾脏组织中妥曲珠利的残留量。将妥曲珠利以20、200和2 000μg/kg的含量分别添加到空白组织中,测得肌肉、肝脏和肾脏组织的回收率大于75%,变异系数均低于7%。用该方法测定肌肉、肝脏和肾脏组织中妥曲珠利的最低检测限为10μg/kg。肉鸡分别在第9,10,16,17,23,24天以8 mg/kg的剂量灌服2.5%妥曲珠利溶液,每天给药1次。最后一次给药后测定不同组织中妥曲珠利的浓度。停药后肌肉、肝脏、肾脏组织中妥曲珠利的残留量逐渐下降;停药第6天后肌肉中检测不到妥曲珠利,停药后第7天肝脏和肾脏组织中均检测不到。     

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.     

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     

Evaluation of the Microbiological Status of Milk and Various Structures in Mammary Glands from Naturally Infected Dairy Cows

A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L₃) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L₃ developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.