组合指数在环境混合物联合毒性研究中的初步应用

化学品在实际环境中总是以组分繁杂多变的混合物形式存在,其混合物的毒性评估与预测一直是环境毒理学研究重点。在环境毒理学领域,浓度加和(concentration addition,CA)及独立作用(independent action,IA)是评估与预测化学混合物联合毒性的经典模型,一般认为CA适用于作用模式相似的混合物体系而IA适用于作用模式相异的混合物体系,但如何使用CA与IA一直存在争议。组合指数(combination index,CI)是在半数效应方程基础上发展起来的不依赖于作用模式的用于混合物联合毒性评估的混合物毒性指数,具有坚实的理论基础,不仅能定性地评估毒理学相互作用,也能定量地评估相互作用的大小,已在药物组合研究中得以广泛应用,近年来已引起环境毒理学研究者兴趣。本文就组合指数及药物组合应用、进入环境毒理学领域、与CA及IA的关系、存在的问题等几个方面进行评述,以期推进CI在化学混合物毒性评估与预测领域中的应用。     

Sorption mechanisms of cephapirin, a veterinary antibiotic, onto quartz and feldspar minerals as detected by Raman spectroscopy

Raman spectroscopy was used to investigate sorption mechanisms of cephapirin (CHP), a veterinary antibiotic, onto quartz (SiO₂) and feldspar (KAlSi₃O₈) at different pH. Sorption occurs by electrostatic attraction, monodentate and bidentate complexation. The zwitterion (CHP^o) adsorbs to a quartz⁽⁺⁾ surface by electrostatic attraction of the carboxylate anion group (-COO⁻) at low pH, but adsorbs to a quartz⁽⁻⁾ surface through electrostatic attraction of the pyridinium cation, and possibly COO⁻ bridge complexes, at higher pH. CHP⁻ bonds to quartz⁽⁻⁾ surfaces by bidentate complexation between one oxygen of -COO⁻ and oxygen from carbonyl of an acetoxymethyl group. On a feldspar^(+/−) surface, CHP^o forms monodentate complexes between CO, and possible -COO⁻ bridges and/or electrostatic attachments to localized edge (hydr)oxy-Al surfaces. CHP⁻ adsorbs to feldspar⁽⁻⁾ through monodentate CO complexation. Similar mechanisms may operate for other cephalosporins. Results demonstrate, for the first time, that Raman techniques can be effective for evaluating sorption mechanisms of antibiotics.     

Effects of veterinary fences on Wildlife conservation in Zimbabwe

In Zimbabwe, veterinary fences are used to control trypanosomiasis and foot- and-mouth disease, two important diseases that threaten cattle production and beef exports. Wildlife is implicated in both instances and the effects of fences on wildlife conservation and land use are discussed in relation to these two diseases. Advantages and disadvantages related to direct and indirect fence effects are outlined. Although the maintenance of fences for trypanosomiasis control is likely to become obsolete, control of foot- and-mouth disease will rely on fences for the foreseeable future. Most of Zimbabwe's protected wildlife areas are located in marginal agricultural land around the periphery of the country where cattle productivity is low. This land should be excluded from any involvement in the beef export industry rather than attempting its inclusion through cordoning and isolating individual protected areas. Within such land, the need for rigid veterinary restrictions should then disappear and allow more flexible strategies for disease control, including adaptive and imaginative approaches to land-use planning.     

X射线衍射法在有机药物研究中的运用

目前随着新药开发、研制过程中对测试方法要求的不断增高,X射线衍射法因其能快速准确地判断药物晶体而被广泛应用于有机药物研究的各个领域.通过对X射线衍射法中装样方法、θ角度和狭缝的选择等参数研究,以获得该方法测定有机药物成分的最佳工作条件,使该法能为有机药物测定提供满意的图谱和更准确的测定结果.     

有机肥中4类典型兽药抗生素的多残留测定

建立了固相萃取-超高效液相色谱-串联质谱（SPE—UPLC—MS／MS）法同时测定有机肥中7种磺胺类、4种氟喹诺酮类、4种四环素类和3种大环内酯类抗生素残留的方法。采用乙腈和磷酸盐缓冲液（pH=3）的混合液作为有机肥样品的提取溶液,用强阴离子交换柱（SAX）-亲水亲脂平衡萃取柱（HLB）串联进行提取液的富集和纯化。以甲醇-φ=0．1％的甲酸溶液作为流动相,进行液相质谱分析。18种抗生素在5—500μg·kg-1的浓度范围内线性关系良好,决定系数（r2）1〉0．99。以3倍信噪比估算磺胺类、氟喹诺酮类、四环素类和大环内酯类的检测限分别为0．37～4．65、0．43—2．42、0．94～2．78和0．83～4．20μg·kg-1,这4类抗生素50和500μg·kg。2个添加水平的样品平均加标回收率分别为71．6％～94．3％、72．3％～86．7％、71．0％～102．2％和70．7％～93．3％,相对标准偏差在2．1％～11．4％之间。采用所建方法对南京地区市售8种有机肥中18种抗生素含量的测定结果显示,除磺胺类外,其他抗生素均有不同程度的检出。     

土壤环境中四环素类抗生素残留及抗性基因污染的研究进展(Tetracycline Residues and Tetracycline Resistance Gene Pollution in Soil: A Review)

近年来,致病菌耐药性的增加和扩散已成为全世界关注的热点问题,而人类医疗和畜禽养殖业抗生素的滥用正不断加剧这一问题.众多研究表明土壤环境作为一个巨大的抗性基因储存库,在抗性微生物和抗性基因的传播中起重要的作用,具有潜在的生态与健康风险.在总结国内外最新研究基础上,对土壤环境中典型抗生素-四环素类抗生素的主要污染源以及其在土壤中的基本环境行为等进行了分析,并探讨了土壤中四环素类抗性基因的来源、迁移和扩散及分子检测手段等问题.我国作为抗生素的生产和消费大国,抗生素污染问题较其他国家更为严重,而国内相关研究才刚刚起步,迫切需要开展有关环境中抗生素和抗生素抗性基因污染的系统研究.     

Determination of chloramphenicol, enrofloxacin and 29 pesticides residues in bovine milk by liquid chromatography-tandem mass spectrometry

A sensitive method for determination of chloramphenicol, enrofloxacin and 29 pesticides residues in bovine milk by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. Residues of the targets were extracted from milk with acetonitrile, cleaned up by C₁₈-SPE cartridge, and then determined by HPLC-MS/MS. The MS detection was operated in positive or negative ionization mode, depending on the compounds. For confirmation of each target compound, two precursor ion > product ion transitions were selected by multi-reaction monitoring mode (MRM). The method showed good linearity for all the tested compounds over the studied concentration range with correlation coefficient higher than 0.9910. Recoveries for the studied compounds at three spiked levels (0.05, 0.10, 0.19 mg kg⁻¹) in bovine milk were in the range of 71-107% with RSDs not larger than 13.7%, except that recoveries of trifluralin ranged between 62% and 70% at the spiked levels. Limits of quantitation for the analytes were estimated to range between 0.03 × 10⁻³ and 14.5 × 10⁻³ mg kg⁻¹. The proposed method was applied for the determination of the analytes residues in real samples. The found levels of the analytes in milk samples were lower than maximum residues levels (MRL).     

Binding of the veterinary drug tetracycline to bovine hemoglobin and toxicological implications

Tetracycline (TC) is a widely used veterinary drug in animal breeding and fishery. Because of its low bioavailability, the TC residue extensively exists in the environment (e.g. soils, lakes and rivers), which can enter the human body, being potentially harmful. Hemoglobin (Hb) is a protein responsible for oxygen carrying in the vascular system of animals. The aim of this study was to investigate the interaction of bovine hemoglobin (BHb) with TC through spectroscopic and molecular modeling methods. The experimental results revealed that TC can interact with BHb with one binding site to form a TC-BHb complex, mainly through van der Waals interactions and hydrogen bonds. The UV-visible absorption, synchronous fluorescence, and circular dichroism (CD) results revealed that the binding of TC can cause conformational and some microenvironmental changes of BHb, which may affect BHb physiological functions. The synchronous fluorescence experiment disclosed that TC binds into BHb central cavity, which was verified by molecular modeling study. The work contributes to clarify the molecular mechanism of TC toxicity in vivo.     

混凝-氧化法预处理原料药废水

采用混凝-Fenton试剂氧化或混凝-臭氧氧化两种氧化技术预处理上海某医药集团原料药废水。实验结果表明：采用聚合氯化铝（PAC）和聚丙烯酰胺（PAM）复合混凝处理该废水,在混凝pH为9.5、混凝时间1h、PAC和PAM加入量分别为600mg/L和12mg/L时,COD的去除率可达23%;混凝后废水再分别用臭氧氧化和Fenton试剂氧化处理,臭氧氧化明显比Fenton试剂氧化经济有效,在臭氧氧化pH为10、臭氧加入量为15g/L、臭氧氧化时间为1h的条件下,废水COD去除率为27.8%,废水BOD₅/COD明显提高,为后续生化处理提供了良好的条件。     

16种蛇鳞的微皮纹分析

对16种蛇鳞的扫描电镜观察表明,蛇类鳞片微皮纹的基本结构是由d约05μm横行排列的小孔和介于小孔间向后延伸的指状突构成背鳞的微皮纹结构有种的特异性同一种蛇的原动物、蛇蜕和药材标本相同部位的鳞片具有相同的微皮纹特征因此蛇鳞的微皮纹特征亦可作为蛇类药材的鉴别依据之一,并以背鳞的微皮纹特征为依据,编制了16种蛇背鳞微皮纹特征检索表。