高效液相色谱法检测鸩肌肉组织中地美硝唑及其羟基代谢物

地美硝唑（dimetridazole，DMZ）为硝基咪唑类药物，具有抗原虫和抗菌活性，同时具有很强的抗厌氧菌作用，用于治疗鸡组织滴虫病、猪密螺旋体性痢疾、肠道和全身的厌氧菌感染。但它有致癌、致突变及潜在毒性。地美硝唑的主要代谢物羟基地美硝唑（hydroxy dimetridazole，DMZOH）同样可能有致突变性，欧盟和美国都把地美硝唑列为禁用的兽药，我国规定地美硝唑的MRL为0。国外建立了多种检测动物组织中地美硝唑及其他硝基咪唑类药物的检测方法，主要有气相色谱法、高效液相色谱（HPLC）-电化学检测法、高效液相色谱-紫外法、质谱法等。国内谢凯舟等用HPLC测定地美硝唑在肉鸡组织中的残留，沈建忠等分别建立了检测鸡肉、家禽肌肉组织中硝基咪唑类药物的液相色谱法。有关同时检测DMZ和DMZOH的报道较少，且检测限高。因此建立了测定鸡肌肉组织中DMZ和DMZOH的高效液相色谱法。     

高效液相色谱法检测鸡肌肉组织中地美硝唑及其羟基代谢物

地美硝唑(dimetridazole,DMZ)为硝基咪唑类药物,具有抗原虫和抗菌活性,同时具有很强的抗厌氧菌作用,用于治疗鸡组织滴虫病、猪密螺旋体性痢疾、肠道和全身的厌氧菌感染.但它有致癌、致突变及潜在毒性.地美硝唑的主要代谢物羟基地美硝唑(hydroxy dimetridazole,DMZOH)同样可能有致突变性,欧盟和美国都把地美硝唑列为禁用的兽药,我国规定地美硝唑的MRL为0.国外建立了多种检测动物组织中地美硝唑及其他硝基咪唑类药物的检测方法,主要有气相色谱法、高效液相色谱(HPLC)-电化学检测法、高效液相色谱-紫外法、质谱法等.国内谢凯舟等用HPLC测定地美硝唑在肉鸡组织中的残留,沈建忠等分别建立了检测鸡肉、家禽肌肉组织中硝基咪唑类药物的液相色谱法.有关同时检测DMZ和DMZOH的报道较少,且检测限高.因此建立了测定鸡肌肉组织中DMZ和DMZOH的高效液相色谱法.     

超高效液相色谱-串联质谱法测定动物源性食品中硝基咪唑类药物残留量的方法优化

本研究建立了一种超高效液相色谱-串联质谱法测定动物源性食品中硝基咪唑类药物残留量的方法。该方法在硝基咪唑类药物的残留量介于0.300～30.0ng/mL的范围内时具有良好线性关系，5种硝基咪唑类药物标准曲线的相关系数(r)均大于0.999，方法检出限在4.60×10^-2～3.38×10^-1μg/kg范围内，低、中、高不同浓度点加标平均回收率范围分别为74.6%～105.0%、77.4%～106.0%、81.7%～107.0%，相对标准偏差为2.9%～11.7%。试验结果显示，该方法具有快速、简便、准确、灵敏的特点，适用于动物源性食品中硝基咪唑类药物残留量的检测。     

食品中硝基呋喃类药物残留检测方法的研究进展

硝基呋喃类药物作为一类广谱性抗生素,广泛应用于食用性动物疾病的预防与控制中。然而不法分子对此类药物的长期滥用,易使动物体内产生耐药菌株,进而导致抗生素的作用大大降低,同时,食品中药物残留还对人体有“三致”作用（致癌、致畸、致突变作用）。作者对食品中硝基呋喃类抗生素代谢物残留的危害及其检测方法进行了调查,食品中硝基呋喃类药物残留的检测方法主要包括高效液相色谱法、液相色谱-质谱法、液相色谱串联质谱法、酶联免疫分析法、胶体金免疫分析法和荧光免疫分析法,作者概述了这些方法的研究现状,并对今后的研究方向提出建议,以期为以后的方法学研究提供参考。     

盐酸克伦特罗试纸条速测法

目前克伦特罗的检测方法主要有4种,分别是试纸条速测法、酶联免疫吸附测定法、气相色谱-质谱法和高效液相色谱法。酶联免疫吸附测定法、气相色谱-质谱法和高效液相色谱法可以定量检测,但所需仪器设备昂贵,     

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…     

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%.     

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。     

原料乳及乳制品中三聚氰胺检测方法研究

全面分析和比较了目前原料乳及乳制品中三聚氰胺的检测方法,主要包括色谱检测法(高效液相色谱法、气相质谱法、液相色谱-串联质谱法)、光谱检测法(拉曼光谱法、近红外光谱法、荧光光谱法)以及免疫检测方法。     

非甾体抗炎药残留检测方法研究进展

介绍了国内外目前检测非甾体抗炎药(Non-steroidal anti-inflammatory drugs,NSAIDs)的几种主要方法,包括高效液相色谱法、液相色谱-质谱法、气相色谱-质谱法、毛细管电泳法、薄层色谱法、分光光度法等,其检测样品基质以血液、尿液为主,动物组织(肌肉、肝脏等)中NSAIDs残留的检测方法报道较少。     

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.