Duration of Anthelmintic Effect of Three Formulations of Ivermectin (Oral,Injectable and Pour-on) Against Multiple Anthelmintic-Resistant <Emphasis Type="Italic">Haemonchus contortus</Emphasis> in Sheep

We report the results of investigations that were conducted in a sheep flock in Uttaranchal, India where repeated failure of anthelmintic medication was noted. The study revealed that Haemonchus contortus in sheep had developed resistance to benzimidazoles (fenbendazole, mebendazole and albendazole), imidazothiazole (levamisole) and salicylanide (rafoxanide), while it was fully susceptible to avermectins (ivermectin). Further, the suppression of nematode egg output in faeces of sheep naturally infected with multiple anthelmintic-resistant H. contortus following treatment with ivermectin tablet (0.4 mg/kg body weight (bw), orally), ivermectin injection (1% w/v, 0.2 mg/kg bw, subcutaneously) and ivermectin pour-on (0.5 w/v, 0.5 mg/kg bw) was also studied over a period of 10 weeks post treatment. It was noted that ivermectin tablet after initial clearance of infection (faecal egg count reduction 100%), could not prevent establishment of new patent natural infection for even a single day, while ivermectin pour-on and injection prevented the establishment of new infection for 7 and 14 days post treatment, respectively. Maximum protection period (duration for which mean faecal egg count of sheep reaches 500 eggs per gram of faeces or more) of 68 days was recorded in sheep treated with injectable ivermectin, followed by pour-on (60 days) and oral (53 days) preparations.     

细菌附属敏感性：优化药物治疗的新思路

交叉耐药性(cross resistance)是指细菌耐药性进化过程中,对单一药物产生耐药性的同时,也会对结构或作用机理相似的药物产生耐药性的现象。附属敏感性(collateral sensitivity)则指细菌对某一药物敏感性下降时,反而对其他药物敏感性提高的现象。在抗菌药物的持续压力下,细菌会选择性地发生交叉耐药性或附属敏感性两种不同的进化路径。在后抗生素来临的时代背景下,科学家提出了一种新颖的治疗思路：借用细菌对药物的附属敏感性特征进行治疗方案的设计或优化。然而,细菌附属敏感性进化是极为复杂的过程,其发生概率不稳定且规律性不强。为更好地认知细菌附属敏感性的进化规律及应用前景,本文对影响细菌附属敏感性的关键因素及附属敏感性的产生规律进行综述,并以此提出目前研究的不足以及未来发展的可能方向。     

Food animals as reservoirs and potential sources of multidrug-resistant diarrheagenic E. coli pathotypes: Focus on intensive pig farming in South Africa

BackgroundDiarrheagenic E. coli (DEC) strains are a major cause of diarrheal diseases in both developed and developing countries. Healthy asymptomatic animals may be reservoirs of zoonotic DEC, which may enter the food chain via the weak points in hygiene practices.AimWe investigated the prevalence of DEC along the pig production continuum from farm-to-fork.MethodsA total of 417 samples were collected from specific points along the pig production system, that is, farm, transport, abattoir and food. E. coli was isolated and enumerated using Colilert. Ten isolates from each Quanti-tray were selected randomly and phenotypically identified using eosin methylene blue agar selective media. Real-time polymerase chain reaction (PCR) was used to confirm the species and to classify them into the various diarrheagenic pathotypes. Antimicrobial susceptibility was determined against a panel of 20 antibiotics using the Kirby-Bauer disk diffusion method and EUCAST guideline.ResultsThe final sample size consisted of 1044 isolates, of which 45.40% (474/1044) were DEC and 73% (762/1044) were multidrug-resistant. Enteroinvasive E. coli (EIEC) was the most predominant DEC at all the sampling sites.ConclusionThe presence of DEC in food animal production environments and food of animal origin could serve as reservoirs for transmitting these bacteria to humans, especially in occupationally exposed workers and via food. Adherence to good hygienic practices along the pig production continuum is essential for mitigating the risk of transmission and infection, and ensuring food safety.     

系统耦合与荒漠─绿洲草地农业系统─—以祁连山一临泽剖面为例

生态系统内部自由能的积累，使系统失去平衡并趋于同其它生态系统结合，自由能驱使两个或两个以上的生态系统或亚生态系统，通过会聚，超循环和耦合而联合，从而形成具有特殊结构一功能的更高一级的新系统。系统耦合可以多途径解放生态系统中的自由能而增加农业生态系统的生产力，亦即从催化潜势，位差潜势，多稳定潜势及管理潜势中取得能输出。上述过程可作用于农业系统中的四个子系统，这四个子系统各有自己的产品：前植物生产，植物生产，动物生产，外生物生产，从而大幅度提高其生产力。在荒漠─绿洲草地农业生态系统中，本文分别计量了各个子系统的能流单位及其流程，证明它的子系统也可以成功的发生系统耦合，其中绿洲子系统应居关键地位。     

益生菌大肠杆菌Nissle 1917抗逆性能、猪肠上皮细胞黏附率及抑菌效果研究

本试验旨在研究益生菌大肠杆菌Nissle 1917(Ec N)抗逆性能、猪肠上皮细胞黏附率及抑菌效果。采用体外法对Ec N进行生长曲线绘制和耐酸、耐胆盐、耐热性能的测定;以猪肠上皮细胞IPEC-J2细胞为体外细胞模型,考察了Ec N对该细胞的黏附率以及对致病菌大肠杆菌K88的黏附抑制率;同时通过蛋白质印迹法检测了Ec N对IPEC-J2细胞β-防御素-2和Toll样受体4的水平的影响。结果表明:1)Ec N对高酸、高胆盐和高温环境具有一定耐受能力。2)Ec N对IPEC-J2细胞的黏附作用以对数期最佳,黏附率达33.96%,显著高于迟缓期、稳定期和衰亡期(P0.05)。3)Ec N对致病菌大肠杆菌K88具有良好的抑制效果,黏附抑制率达87.84%。4)Ec N还能上调IPEC-J2细胞β-防御素-2和Toll样受体4水平。结果提示,益生菌Ec N具有较好的抗逆性能,能够良好地黏附猪肠上皮细胞,对致病菌大肠杆菌K88具有良好的抑制作用。     

SNP genetic polymorphisms of MDR-1, CYP1A2 and CYPB11 genes in four canine breeds upon toxicological evaluation

The fields of pharmacogenetics and pharmacogenomics have become increasingly promising regarding the clinical application of genetic data to aid in prevention of adverse reactions. Specific screening tests can predict which animals express modified proteins or genetic sequences responsible for adverse effects associated with a drug. Among the genetic variations that have been investigated in dogs, the multidrug resistance gene (MDR) is the best studied. However, other genes such as CYP1A2 and CYP2B11 control the protein syntheses involved in the metabolism of many drugs. In the present study, the MDR-1, CYP1A2 and CYP2B11 genes were examined to identify SNP polymorphisms associated with these genes in the following four canine breeds: Uruguayan Cimarron, Border Collie, Labrador Retriever and German Shepherd. The results revealed that several SNPs of the CYP1A2 and CYP2B11 genes are potential targets for drug sensitivity investigations.     

茉莉酸甲酯和磷酸氢二钾诱导柱花草对炭疽病的抗性

探究茉莉酸甲酯（Methyl Jasmonate,MeJA）和磷酸氢二钾（K2HPO4）诱导柱花草对炭疽病的抵抗作用。结果表明,二者浓度分别为0.001~0.1 mgmL-1和10~50 mmolL-1时,病情指数均显著降低（P0.05）,最佳诱导浓度分别是0.001 mgmL-1和30 mmolL-1,诱导效果分别是64.84 %和54.40 %。0.001 mgmL-1 MeJA处理组的过氧化物酶（POD）及多酚氧化酶（PPO）活性在48 h达到最大值,显著高于对照组。30 mmolL-1 K2HPO4处理组的POD与PPO活性分别在48和24 h达到最大值,显著高于对照组。两种诱抗剂处理的POD和PPO活性在接种早期增加了柱花草对炭疽菌的侵染的抵御能力,进而提高植株的抗病性。30 mmolL-1 K2HPO4处理组的过氧化氢酶（CAT）活性在48~72 h内上升,显著高于对照组,而0.001 mgmL-1 MeJA处理组的CAT活性除72 h显著低于对照组,其他时间点与对照组相差不大。说明在诱导柱花草抗病性方面,两种诱导抗性剂处理的诱抗效果与POD、PPO和CAT的酶活性的诱导的时间及程度有关。     

鸭茅幼苗生长及形态对铝胁迫的响应

选取我国西南地区的鸭茅(Dactylis glomerata)主栽品种‘德纳塔’、‘安巴’、‘宝兴’和‘牧友’为供试材料,研究酸性环境下不同梯度的铝离子(0,10,30,50和100 μM)对鸭茅幼苗生长及形态的影响。结果表明:铝胁迫下,鸭茅枝条干重、根系干重、植株形态及根系伸长均受到显著抑制,且随着浓度的增加呈现出下降趋势;低浓度(10～30 μM)铝离子处理对鸭茅生长造成的抑制较弱,对鸭茅植株的健康形态塑造没有造成影响;而高浓度(≥50 μM)铝离子处理则对鸭茅植株根系伸长和植株形态造成严重的抑制,不利于植株后期的健康生长;供试鸭茅地下部根系积累铝的量要大于地上部枝条,且品种间存在一定差异,‘牧友’根系中铝含量最低,耐受性较强。表明鸭茅通过改变植株形态和调控自身积累铝的水平来应对酸性土壤中的铝离子胁迫,但是酸性铝离子环境对鸭茅早期生长仍具有一定的毒害作用,低浓度造成的影响较小,而高浓度则对鸭茅植株生长和形态塑造均造成不良的影响。     

饲用小黑麦在海河平原区的生产性能及适应性评价

在海河平原区对11个饲用小黑麦品种进行了生产性能比较试验以及旱作条件下适应性,试验得出:冀饲-1成熟早,生育期短,抽穗期比对照中新830提前6d,干草产量高,比对照中新830提高26.7%,能与春播作物形成一年两作,适于在海河平原区推广利用;冀饲-2在海河平原地区鲜干草产量均较高,分别比对照中新830增产4 854.3kg/hm2和777.0kg/hm2,属于高产品种,茎叶比低,叶量丰富是海河平原区主要品种推广种植。旱作条件下种植,饲用小黑麦株高比正常管理条件下降低64.6%~83.4%,分蘖数和成穗数分别减少60.0%~74.7%和85.3%~98.1%,鲜干草产量分别降低69.3%和70.2%,利用价值不大,只有在一定的灌溉和施肥条件下种植才能产生较好经济效益。