鸡肝组织中磺胺类药物多残留分析法

建立了鸡肝组织中磺胺嘧啶、磺胺二甲基嘧啶、磺胺甲氧吡嗪、磺胺－6－甲氧嘧啶、磺胺甲恶唑、磺胺－2，6－二甲氧嘧啶和磺胺喹恶啉的多残留高效液相色谱分析法。样品经乙腈提取、正己烷液－液分配和碱性氧化铝柱固相萃取法净化后用反相高效液相色谱法测定（UV270nm）。7种磺胺类药物标准曲线的相关系数（r^2)为0．9991－1．0000（0.01μg/ml-0.5μg/ml）。在0.05mg/kg-0.5mg/kg浓度范围内，磺胺类药物的回收率为68．8％－100．0％，变异系数为1．3％－12．0％。 检测限为0．01mg/kg-0.03mg/kg，定量限低于0.05mg/kg。     

磺胺对甲氧嘧啶和二甲氧苄啶在肉鸡体内的残留消除

采用高效液相色谱-串联质谱法研究磺胺对甲氧嘧啶(SMD)和二甲氧苄啶(DVD)预混剂在白羽肉鸡体内各组织中的残留消除规律。对48只健康白羽肉鸡连续饲喂添加1 000mg/kg磺胺对甲氧嘧啶和二甲氧苄啶预混剂(含SMD 200mg,DVD 40mg)的全价饲料10d,在停药后4h,1、3、6、9、12、15d分别宰杀6只鸡,采集各组织进行药物残留测定。通过空白样品添加回收试验,所有基质中SMD和DVD的定量限分别为10μg/kg和5μg/kg,SMD和DVD分别在50、100、200μg/kg和25、50、100μg/kg 3个添加水平下的平均回收率为71.7%~102.3%,相对标准偏差为1.0%~11.9%。结果表明,磺胺对甲氧嘧啶和二甲氧苄啶预混剂在肾脏中残留量最高,肝脏其次;肌肉和皮脂中的残留量显著低于肝脏和肾脏,停药9d时,残留量低于药物残留限量。综合各组织中总残留量和最高残留限量规定,建议磺胺对甲氧嘧啶和二甲氧苄啶预混剂在鸡的休药期为7d。     

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%。     

高效液相色谱-串联质谱法同时检测鸡蛋中金刚乙胺和金刚烷胺药物残留研究

为建立一种同时检测鸡蛋中金刚乙胺和金刚烷胺药物残留的高效液相色谱-串联质谱法，试验样品采用1.0%乙酸乙腈提取后，以0.1%甲酸水和甲醇溶液作为流动相进行梯度洗脱，经Waters XBridge C₁₈Column分离，正离子多反应监测模式检测。结果显示：两种药物在0.5～100μg/L范围内均呈良好的线性关系(R²>0.997)；盐酸金刚乙胺和盐酸金刚烷胺检出限均为0.3μg/kg，定量限均为1.0μg/kg；盐酸金刚乙胺平均回收率为87.43%～98.64%，批内和批间变异系数均≤0.45%，盐酸金刚烷胺平均回收率为96.60%～102.13%，批内和批间变异系数均≤0.22%。研究表明，建立的高效液相色谱-串联质谱法简便、灵敏、准确，适用于鸡蛋中金刚乙胺和金刚烷胺药物残留检测。     

鸡组织中磺胺对甲氧嘧啶和二甲氧苄啶残留的HPLC-MS/MS测定

建立了同时测定鸡组织中残留的磺胺对甲氧嘧啶(SMD)和二甲氧苄啶(DVD)了的高效液相色谱-串联质谱法(HPLC-MS/MS)。样品经乙腈提取,取部分提取液用正己烷脱脂后于氮气吹干,残渣用流动相溶解并定容后上机检测,外标法定量。采用C18色谱柱,流动相为乙腈和1mL/L甲酸水溶液。选择1个母离子和2个子离子进行反应监测,对磺胺对甲氧嘧啶和二甲氧苄啶残留进行定性,选择信号最强的子离子进行定量。结果显示,SMD和DVD分别在1ng/mL~200ng/mL和0.5ng/mL~100ng/mL范围内呈良好线性关系,相关系数R20.992。通过空白样品添加回收试验,所有基质中SMD和DVD的定量限分别为10μg/kg和5μg/kg,SMD和DVD分别在50、100、200μg/kg和25、50、100μg/kg 3个添加水平下的回收率为71.7%~115.0%,相对标准偏差为1.8%~13.2%,该方法定量限低,灵敏度高,重现性好,符合相关研究的要求。     

固相萃取-高效液相色谱法测定饲料中5种磺胺类药物的研究

建立了固相萃取-高效液相色谱(SPE-HPLC)测定饲料中磺胺嘧啶、磺胺间甲氧嘧啶、磺胺二甲基嘧啶、磺胺甲恶唑、磺胺喹恶啉5种磺胺类药物的方法。考察了碱性氧化铝小柱的最大饱和容量及洗脱条件,优化了色谱条件:流动相为乙腈和水(257∶5,v/v),流速为1.0 mL/min,检测波长为270 nm。在优化条件下,方法的最低定量限分别为磺胺嘧啶、磺胺间甲氧嘧啶5 mg/kg;磺胺二甲基嘧啶、磺胺甲恶唑、磺胺喹恶啉2 mg/kg。方法的线性范围在0.2～200μg/mL之间,线性相关系数高于0.9996。将该方法用于鸡配合饲料、猪配合饲料和浓缩饲料中磺胺类药物残留的测定,不同添加浓度的回收率均高于80%,相对标准偏差≤10%,能够满足实际样品的分析要求。     

鸡血浆中磺胺氯吡嗪钠和甲氧苄啶含量HPLC检测方法的建立

建立了鸡血浆中磺胺氯吡嗪钠和甲氧苄啶含量测定的HPLC方法。对鸡血浆中磺胺氯吡嗪和甲氧苄啶采用乙腈提取和净化,梯度洗脱,高效液相色谱紫外检测法测定,外标法定量。流动相为甲醇-0.02 mol/L磷酸二氢钾水溶液。紫外测定时采用双波长检测:磺胺氯吡嗪检测波长为268 nm,甲氧苄啶检测波长为240 nm。空白血浆添加磺胺氯吡嗪和甲氧苄啶分别在0.1～70.0μg/m L和0.05～5.00μg/m L范围内线性关系良好(R~2均大于0.9999),磺胺氯吡嗪和甲氧苄啶的检测限分别为0.05μg/m L和0.025μg/m L,定量限分别为0.1μg/m L和0.05μg/m L。空白血浆添加磺胺氯吡嗪和甲氧苄啶在各自线性范围内,批内变异系数分别小于6.84%和7.55%,批间系数分别小于5.23%和6.81%。本研究建立的鸡血浆中磺胺氯吡嗪和甲氧苄啶的提取和净化方法,适用于鸡血浆中磺胺氯吡嗪和甲氧苄啶含量的单个或同时测定。     

磺胺氯吡嗪钠二甲氧苄啶溶液质量标准研究

研究磺胺氯吡嗪钠二甲氧苄啶溶液的质量标准。以高效液相色谱法测定溶液中磺胺氯吡嗪钠和二甲氧苄啶含量,采用Sino Chrom ODS-BP色谱柱,以磷酸二氢钾溶液∶甲醇为流动相,磺胺氯吡嗪钠和二甲氧苄啶在0.5-100.0μg/m L和0.3-45.0μg/m L范围内线性关系良好,平均回收率分别为99.9%和99.1%。该研究建立的色谱条件可同时检测2种成分,简便快捷。     

高效液相色谱法同时测定猪肌肉中氟喹诺酮类和磺胺类药物残留

为了建立同时检测猪肌肉组织中3种喹诺酮类药物(环丙沙星、单诺沙星、恩诺沙星)和3种磺胺类药物(磺胺二甲基嘧啶、磺胺间甲氧嘧啶、磺胺甲唑)的高效液相色谱(HPLC)检测方法,试验采用磷酸盐缓冲液(pH值为6)提取动物组织样品,混合型阳离子交换(MCX)固相萃取柱净化,无水乙醇平衡、洗涤,无水乙醇-氨水(95/5)洗脱,Symmetry C18色谱柱分离,紫外检测器串联荧光检测器同时测定。线性良好,相关系数(r2)大于0.998 7,平均回收率为70.6%~89.3%,相对标准偏差为2.5%~13.4%。喹诺酮类药物的检出限为0.04~0.20μg/kg,定量限为0.2~1.0μg/kg;磺胺类药物的检出限为4μg/kg,定量限为15μg/kg。结果表明:HPLC法具有快速、环保的特点,可以用于猪肌肉组织中氟喹诺酮类和磺胺类药物的常规残留检测。     

固相萃取-高效液相色谱法同时检测奶牛粪污中5种磺胺类抗生素

建立的固相萃取-高效液相色谱法具有灵敏度高、检测限低的特点,可同时定量检测奶牛粪污中磺胺嘧啶、磺胺二甲嘧啶、磺胺间甲氧嘧啶、磺胺甲恶唑、磺胺喹噁啉的残留。采用C18色谱柱(500 mm×4.6 nm, 5μm),以0.3%的乙酸-乙腈溶液为流动相,在流速1.0 mL/min、检测波长270 nm、柱温30℃条件下,5种抗生素均能达到基线分离;3倍信噪比下,5种抗生素的检出限均为20μg/kg。在加标浓度50μg/kg条件下,奶牛粪污样品经前处理、MCX固相萃取小柱富集净化后,五种磺胺类抗生素回收率达到75%～80%,相对标准偏差为2.8%～3.9%。此方法检测了某规模化奶牛场粪污中磺胺类抗生素残留,结果显示,磺胺嘧啶的浓度范围在45～50μg/kg,其他抗生素无检出。     

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.