联苯胺比色法测定饲料中有机硒的含量

本文介绍了一种简便可靠的测定富硒酵母中有机硒含量的方法。采用双氧水∶高氯酸∶硫酸为3∶3∶1的消化液处理样品,用联苯胺比色法测定样品硒含量。在酸性条件下,硒与3,3′-二氨基联苯胺作用,生成黄色络合物(Se-DAB)。在pH值6.5～7.0左右时,用甲苯萃取,根据有机层显色的程度,可进行分光光度法测定。测定总硒和无机硒,用差减法求出有机硒含量。     

微波消解-石墨炉原子吸收光谱法测定醋酸地塞米松中的微量硒

采用微波制样技术对样品进行消解,减少了消化过程中硒的损失,利用石墨炉原子吸收光谱法对醋酸地塞米松中微量硒进行测定.以4 mg/mL Pd(NO3)2作为基体改进剂,灰化温度为950 ℃,原子化温度为2 100 ℃时,经氘灯校正背景,测定硒含量,回收率在89.24%～112.37% 之间,方法的相对标准偏差为7.42%,检出限为0.53 ng/mL.该法具有简便、快速、灵敏、稳定、准确等优点,适用于醋酸地塞米松中微量硒的分析测定.     

分子荧光紧密内插法快速测定饲料中的硒

为创建一种新型测定饲料中硒的方法,用微波消解样品,在酸性条件下,硒与2,3-二氨基萘(DAN)反应生成具有强荧光特性的4,5-苯并苤硒脑,其荧光强度与硒的含量成正比,以此用分子荧光紧密内插法测定饲料中的硒。结果表明:最佳测定条件为pH 1.5、DAN试剂4.00 mL、EDTA混合液20.00 mL、水浴时间6 min。饲料样品中硒的含量大于5.83 mg/kg,加标回收率大于92%。本方法具有快速简便、成本低廉、样品用量少、消解完全、无需测定空白和绘制标准曲线的优点,有较强的推广应用价值。     

微波消解—石墨炉原子吸收光谱法测定牛奶中铅的含量

作者研究了用微波消解法对牛奶样品进行前处理,操作简便,减少了操作带来的误差,再用石墨炉原子吸收光谱法测定其中铅的含量。该方法测定的线性范围在0～40 ng/mL,相关系数r=0.9998。牛奶样品添加回收率为90%～95%。该方法准确、可靠,而且大大提高了检测效率。     

氢化物发生-原子荧光光谱法测定饲料用香菇菌糠中硒含量的方法研究

建立饲料用香菇菌糠中硒检测的方法;利用正交试验设计对仪器的各项参数进行优化,采用单因素试验分析最佳氢化反应条件,通过混合酸消解对样品进行前处理,采用氢化物-原子荧光光谱仪测定样品中的硒含量;该方法在硒浓度0～5μg/l范围内,相关系数r为0.999 5,检出限为0.03μg/l,回收率为95.12%～98.30%,精密度为4.2%(n=6);检测取自河北省平泉、阜平、平山三个产区的香菇菌糠,其硒含量依次为2.54、2.77、2.62μg/kg;该方法线性良好,灵敏度和准确度高,精密度好,适用于饲料用香菇菌糠中硒含量的测定。     

氢化物发生-原子荧光光谱法测定牛肉中的硒含量

本试验采用了氢化物发生—原子荧光光谱法测定牛肉中的硒,通过消解液、预还原剂、介质酸的选择等优化了试验条件并测定其检出限、精密度、加标回收率等。结果显示本试验选用2∶1的混合酸作为消解液,6mol/L HCl作为预还原剂,体积比为10%的HCl作为介质酸。硒在0~8μg/L的范围内呈良好的线性关系,相关系数为0.9999,检出限为0.01ng/mL。在20、30和40μg/L 3个添加水平下牛肉的回收率为94%~104%,相对标准偏差(RSD)为3.80%。该方法具有简便、有效等特点,对肉制品中硒的测定具有一定的参考意义。     

微波消解-冷原子吸收法测定虾粉中的汞

采用微波消解技术冷原子吸收法分析测定虾粉样品中的总汞.探讨了微波条件的选择、微波条件对回收率的影响以及使用微波与测汞仪时的注意事项.建立了用微波消解-冷原子吸收法测定虾粉中总汞的方法,样品回收率为98.3%～101%,RSD%为1.2%～2.1%.     

高效液相色谱-电感耦合等离子体质谱法测定富硒蛋白多糖中纳米单质硒含量

本试验旨在建立高效、准确、快速测定富硒蛋白多糖中纳米单质硒含量的方法。将25 mg阴沟肠杆菌(Enterobacter cloacae)Z0206产富硒蛋白多糖样品悬浮在3 mL蒸馏水中,在3 mgⅩⅣ型蛋白酶作用下超声处理30 min(37℃),将酶解液离心得到的沉淀物(纳米单质硒)在常温下经双氧水-盐酸(H_2O_2-HCl)体系消解,所得溶液直接经高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)分析[以PRP X100阴离子色谱柱对样品中的亚硒根离子(SeO_2-3)进行分离,流动相组成为5 mmol/L柠檬酸水溶液(pH 4.5)],测得样品中纳米单质硒含量为2 439μg/g。以国家标准(GB/T 13883—2008)方法[样品以硝酸-高氯酸(HNO_3-HClO_4)体系消解处理,经氢化物发生-原子荧光(HG-AFS)分析]为对照,测得样品中纳米单质硒含量为2 450μg/g。2种方法的测定结果高度一致。与GB/T 13883—2008中描述的方法相比,采用本试验建立的氧化体系条件更温和、快速并且易于控制,适用于纳米单质硒的快速检测。     

氢化物发生-原子荧光光谱法同时测定饲料中的砷、汞、硒和镉

研究采用消化罐消解方法,应用氢化物发生-原子荧光光谱法同时进行饲料中砷、汞、硒、镉的测定,并对各种试验条件及影响因素进行了探讨。结果表明:采用HNO3-HClO4体系在消化罐内进行湿法消解,样品消解完全且所用时间短;使用HCl作为反应介质效果良好;在一定浓度范围内4种元素的浓度与荧光响应值均有良好的线性关系;4种元素的加标回收率均在90%以上;精密度(RSD,n=11)不大于1.7%。建立的方法简便、稳定可靠,检测成本低,结果满意,可用于饲料中砷、汞、硒和铅的同步检测。     

氢化物发生-原子荧光光谱法测定鹿饲料中硒含量的方法研究

文章深入研究了氢化物发生-原子荧光光谱法测定鹿饲料中硒的分析方法。研究结果表明,采用硝酸-高氯酸(8+1)混合酸消解样品,以2%盐酸介质作为载流,样品酸度控制在20%时进行样品分析,测定结果准确可靠。该方法的线性范围0~10μg/l,相关系数优于0.999,检出限0.07μg/l,加标回收率85.3%~116.9%。此方法具有简单易行、精密度好、回收率高等优点,适用于饲料中硒含量的测定。     

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.     

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.     

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.     

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