Comparative pharmacokinetics of marbofloxacin in healthy and Mannheimia haemolytica infected calves

The pharmacokinetics of marbofloxacin were investigated in healthy (n=8) and Mannheimia haemolytica naturally infected (n=8) Simmental ruminant calves following intravenous (i.v.) and intramuscular (i.m.) administration of 2 mg kg(-1) body weight. The concentration of marbofloxacin in plasma was measured using high performance liquid chromatography with ultraviolet detection. Following i.v. administration of the drug, the elimination half-life (t(1/2 beta)) and mean residence time (MRT) were significantly longer in diseased calves (8.2h; 11.13 h) than in healthy ones (4.6 h; 6.1 h), respectively. The value of total body clearance (CL(B)) was larger in healthy calves (3 ml min(-1) kg(-1)) than in diseased ones (1.3 ml min(-1) kg(-1)). After single intramuscular (i.m.) administration of the drug, the elimination half-life, mean residence time (MRT) and maximum plasma concentration (C(max)) were higher in diseased calves (8.0, 12 h, 2.32 microg ml(-1)) than in healthy ones (4.7, 7.4 h, 1.4 microg ml(-1)), respectively. The plasma concentrations and AUC following administration of the drug by both routes were significantly higher in diseased calves than in healthy ones. Protein binding of Marbofloxacin was not significantly different in healthy and diseased calves. The mean value for MIC of marbofloxacin for M. haemolytica was 0.1+/-0.06 microg ml(-1). The C(max)/MIC and AUC(24)/MIC ratios were significantly higher in diseased calves (13.0-64.4 and 125-618 h) than in healthy calves (8-38.33 and 66.34-328 h). The obtained results for surrogate markers of antimicrobial activity (C(max)/MIC, AUC/MIC and T > or = MIC) indicate the excellent pharmacodynamic characteristics of the drug in diseased calves with M. haemolytica, which can be expected to optimize the clinical efficacy and minimize the development of resistance.     

Multiple hepatic peribiliary cysts in a young pig

Histopathologic features of hepatic peribiliary cysts were described in a young slaughtered pig. The animal was an apparently healthy 6-month-old pig of mixed breed. Macroscopically, all lobes of the liver contained numerous cysts of varying size containing serous fluid in all lobes. Histopathologically, the cysts were located mainly around the large bile duct and in the connective tissue of the portal tracts. Within serial sections, these cysts were assumed to be solitary or multilocular, but they were separated from the bile duct. The cysts were lined by a single layer of columnar, cuboidal, and flattened epithelial cells. Occasionally, goblet cells were observed. The epithelial cells were stained with periodic acid-Schiff/alcian blue and high-iron diamine/alcian blue, indicating the presence of neutral mucin, sialomucin, and sulfomucin. Grimalius' method revealed the presence of endocrine cells in the lining epithelium. There was no bile pigment in the cysts by the Hall method.     

马γ-干扰素成熟蛋白基因在大肠埃希氏茵中表达及其多克隆抗体制备

采用RT-PCR从ConA刺激的马外周血单核细胞（PBMC）中扩增获得含信号肽的马γ-干扰素（Equine interferon-γ，EIFN-γ）基因，将其克隆至载体pCR2．1-TOPO中。通过PCR方法从重组质粒（pCR-EIFN-γ）中扩增马干扰素成熟蛋白（MatureEIFN-γ，mEIFN-γ）基因，并将其亚克隆至原核表达载体pET-28a（＋）。重组子经测序鉴定正确后转化至大肠杆菌BL21（DE3），经IPTG诱导，对其产物进行SDS-PAGE分析和Western blot鉴定，将纯化后的表达产物免疫新西兰白兔制备多克隆抗体。结果表明，mEIFN-γ基因全长为441b口，含一个开放阅读框，编码146个氨基酸的成熟蛋白；对其表达产物以可溶性和包涵体两种形式存在，重组蛋白相对分子量约为18Ku，且具有免疫反应活性。mEIFN-γ基因在大肠杆菌中高效表达并在非变性和变性条件下，采用Ni^＋亲和层析纯化方法均可获得高纯度的重组马γ-干扰素制备的多克隆抗体，为建立马γ-干扰素检测方法、监测机体免疫状态和研究机体免疫机制奠定了基础。     

人类艾滋病动物模型研究进展

许多疾病的研究离不开动物模型,它是进行发病机制、药物治疗和疫苗研究的必需条件之一。文章综述了近年来国内外建立艾滋病动物模型研究方面的新进展,包括了灵长类动物和非灵长类动物,并对建立艾滋病动物模型的发展前景进行展望。     

The effect of 6‐ and 8‐hour light‐dark cycles on egg production and pattern of ovipositions

1. Two flocks of 60 laying hens were transferred from 14 h light (L): 10 h dark (D), to repeated 3L:3Dor4L:4D lighting schedules at 37 weeks of age. Egg production decreased slightly but egg weight and shell quality improved.

2. The intake of low‐calcium diet and of oyster shell were similar for each light period of each lighting regimen.

3. Ovipositions were distributed virtually at random throughout the day and the mean interval between successive eggs within a clutch was increased.

4. Reducing the total daily photoperiod from 12 to 6 h decreased daily food consumption.     

驼绒藜属牧草种苗耐盐性评价及生理基础研究

对7份驼绒藜属材料种子萌发及幼苗进行耐盐性研究。结果表明,种苗具有较高的耐盐性,在种间及种内生态型间存在差异,其中华北驼绒藜耐盐性最强,其次为华北驼绒藜科尔沁生态型,驼绒藜荒漠生态型和心叶驼绒藜耐盐性最弱。种苗的耐盐能力和种子的活力呈正相关,在恶劣生境条件下形成的种子活力较低,种苗的耐盐力也较低;种苗耐盐半致死浓度与种子活力3项指标呈显著或极显著正相关(r=0.82^*、0.93^**、0.90^**)。而盐性生理基础的研究结果表明,种子耐盐性的指标与种子含氮量呈极显著正相关(r=0.88^**、0.90^**),与种子含磷量呈正相关(r=0.77、0.68),与含糖量相关性较小(r=-0.33～0.55)。初步认为种子耐盐半致死浓度、种子活力指数和含氮量可以作为种子耐盐性评价和选育的生理指标。