A sensitive microassay for the determination of hemolytic complement activity in bovine milk

A ⁵¹Cr release microhemolytic complement assay is described to detect hemolytic complement activity in bovine milk. ⁵¹Cr-labeled guinea-pig erythrocytes (GPRBC), which have been sensitized with a subagglutinating amount of rabbit anti-GPRBC, are placed in microtiter plates. Pooled bovine sera as source of complement to achieve about 50% of ⁵¹Cr release were added to each well prior to the addition of the samples on the test. Determination of CH100 titer was obtained by difference of counting between heated and unheated diluted whey samples from a standard linear regression. Comparative hemolytic values throughout lactation were established for the first time and confirmed the improved sensitivity of the assay.     

A comparison of an enzymatic and a gas-chromatographic method for measuring the acetate concentration in the blood plasma of cattle

The concentration of acetate in blood plasma was measured by both a gas-liquid chromatographic method and an enzymatic method using acetyl-CoA synthetase. When acetate was measured enzymatically without previous protein precipitation, the apparent concentration was lower than when the concentration measured by either a gas-chromatographic method or by the enzymatic method after protein precipitation with perchloric acid and neutralization.     

Comparison of serum, milk and urine as samples in an enzyme immunoassay for bovine leukaemia virus infection

Serum, milk and urine specimens were taken from 15 bovine leukaemia virus (BLV)-positive and 20 BLV-negative cattle which had been determined previously to be infected or not by the use of a monoclonal enzyme-linked immunosorbent assay (ELISA). An ELISA was performed on the samples for the detection of IgG₁ antibodies to the BLv surface glycoprotein, gp 51. The three types of samples had parallel optical density (OD) values apart from three urine samples which, although accepted as- negative for anti-BLv antibodies, had numerically higher ODS than those of control BLV-negative animals. Therefore, detection of IgG₁ antibodies against BLv in the urine of naturally infected animals could be an indication for the use of urine for diagnosis of BLV infection.     

A simple method for determination of pepsinogen in bovine serum and plasma.

Calf serum pepsinogen can be determined by radial diffusion in a casein-containiing agarose gel prepared at pH 8.2 and afterwards immersed in a BaGla-containing buffer, pH 2.4, whereby the casein is precipitated homogeneously. Serum samples are placed in wells in the gel, and at the low pH pepsinogen present in the samples will be activated and the casein digested, whereby transparent, circular zones are formed in the otherwise opaque gel. The diameter of these zones can be measured directly and used as an expression of the serum pepsinogen level. On analysis of a number of sera from calves with or without ostertagiasis a positive correlation was found between the results obtained by this method and conventional absorption photometry (r = 0.87, n = 55).     

A high-performance liquid chromatography method for determination of 4-aminopyridine in tissues and urine

An analytical method was developed to measure 4-aminopyridine in tissues and urine to determine appropriate diagnostic samples in acute poisoning cases. Tissues from rats dosed with 4-aminopyridine were extracted with methylene chloride. Extracts were analyzed by high-performance liquid chromatography using an isocratic solvent system of acetonitrile and aqueous solution (15/85 v/v) consisting of 0.015 M sodium salt of l-heptane-sulfonic acid, 0.002 M tetramethylammonium bromide, and 0.01 M sodium dihydrogen phosphate adjusted to pH 3.0 with phosphoric acid. We concluded that suitable diagnostic samples for acute poisoning cases include stomach contents, kidney, liver, and urine.     

液相色谱法测定牛奶中三聚氰胺残留量的不确定度

通过数学建模,对GB/T22388-2008中HPLC法测定牛奶中三聚氰胺残留量的不确定度进行分析。将各个分量分化,运用最小二乘法对标准曲线拟合的不确定度,用极差法对测定次数较少时引起的不确定度,添加回收率的不确定度等进行分析。结果表明,合成标准不确定度U（X）=0.040,当取样量为2.00g,k=2（95%置信度）时,测得牛奶中三聚氰胺的含量为（2.00±0.160）mg/kg。     

Flow cytofluorometric characterization of bovine blood and milk leukocytes

Flow cytometry and sorting proved to be a rapid method that facilitated the identification of different leukocyte populations in bovine blood and milk. After briefly incubating whole blood and milk samples in a hypotonic phosphate buffer, containing supravital acridine orange, 5 classes of leukocytes were found in the blood (lymphocytes, neutrophils, eosinophils, basophils, and monocytes) and 4 in the milk (lymphocytes, neutrophils, monocytes, and macrophages) by flow cytometry. Cells were morphologically identified by fluorescent microscopy after flow cytometric sorting and by light microscopy after Papanicolaous staining. Udder parenchymal and ductal tissue cells (secretory and epithelial cells) were not found in the milk samples evaluated. Large differences in the total and differential cell counts were found in the different milk secretions.     

A method for separation of bovine blood leukocytes for in vitro studies.

Various methods have been developed for separation of the cellular components of blood. Size and density differences in cellular blood elements of various animal species necessitate the use of specific separative procedures. This study describes a method which combines isopycnic density-gradient centrifugation with erythrocyte aggregation as a means of isolating leukocytes from bovine blood. The procedure yields a viable population of mixed leukocytes which has proven useful for cell culture and in vitro tests of cell-mediated immunity.     

泌乳反刍动物乳蛋白的合成机理及调控途径的研究

<正>乳蛋白含有机体几乎所有的必需氨基酸,具有较高的营养价值。乳蛋白的消化会产生一系列的生物活性肽,对人体有调节生理,预防疾病和抗感染等生理功能,是一种具有潜力的营养保健性物质,人类对其消费量很大。不过,在不同的生产条件下,乳腺乳蛋白的合成能力不同,乳蛋白的产量也有所变化。有报道     

动物尿液中盐酸克伦特罗残留检测方法的改进

通过对NY/XQ421-2003动物尿液中盐酸克伦特罗残留检测方法(GC/MS)的改进,可使该方法操作简便,灵敏度提高,稳定性增强,回收率提高到92%。     

A simple method for the in vitro determination of phagocytic activity of bovine polymorphonuclear leukocytes

A simple method for the in vitro determination of the phagocytic activity of bovine polymorphonuclear leukocytes (PMNL) is described. An enriched PMNL population was obtained from peripheral blood of healthy cattle and mixed with opsonized Candida utilis or with opsonized bovine red blood cells on BSA treated coverglass slides. The phagocytosis and killing of C. utilis was determined simultaneously on the coverglass slides stained with acridine orange. Phagocytosis of bovine erythrocytes was determined by microscopic examination of the Wright-Giemsa stained slides. This method is appropriate under limited laboratory conditions because it does not require highly sophisticated equipment and materials, it is easy and rapid to perform, reproducible and inexpensive. Therefore, it could be used as a first evaluation of the phagocytic activity of bovine PMNL.     

从血凝块中提取DNA的快捷方法

将7 mL全血去血清后的血凝块用携带不锈钢均质头的均质器裂解后,加入红细胞裂解液处理至无血凝块存在,得到1 mL左右的白细胞提取物,可较完全地去除红细胞成分。白细胞提取物提取的DNA成分经凝胶电泳分析,可得到较清晰的DNA条带。用牛特异性引物从所有血凝块扩增出271 bp的牛特异性条带,用血凝块处理后的细胞沉淀添加病毒悬液提取的DNA作BHV1病毒gB-PCR检测,结果显示添加BHV1的血凝块样品均出现478 bp的BHV1-gB特异性条带。