Resistance to a triple combination of broad-spectrum anthelmintics in naturally-acquired Ostertagia circumcincta infections in sheep

Extract

To the veterinary practitioner, the challenge of managing a cat with renal failure is very real. The specific goals of therapy are to:     

RP-HPLC法测定银杏叶提取物类脂质体中黄酮和萜类内酯含量的优化方法

建立反相高效液相色谱法(RP-HPLC),测定银杏叶提取物类脂质体(EGBN)中银杏3种黄酮化合物(槲皮素、山奈素、异鼠李素)和4种萜类内酯(银杏内酯A、银杏内酯B、银杏内酯C、白果内酯)的含量,及银杏总黄酮醇苷的饱和溶解度.采用透析法提取出EGBN中的银杏黄酮.黄酮应用Agilent HC-C18色谱柱(4.6 mm× 250.0 mm,5μm),以V(乙腈)∶V(0.4％磷酸)=28∶72为流动相,流速1.0 mL/min,检测波长360nm,柱温40℃.萜类内酯应用Agilent HC-C18色谱柱(4.6 mm×250.0 mm,5μm),以V(甲醇)∶V(四氢呋喃)∶V(水)=46∶7∶47为流动相,流速0.8 mL/min,NEB温度60℃,EVA温度105℃.结果表明:透析法可以将EGBN中有效成分很好的分离,从而易于测定其中药物含量.在此色谱条件下,槲皮素、山奈素、异鼠李素分别在2.01～100.50,1.01～50.3,0.26～ 12.8 mg/mL范围内与峰面积呈良好的线性关系;银杏内酯A、银杏内酯B、银杏内酯C、白果内酯采用外标两点测定;平均加样回收率(n=6)均在(100±2)％范围内;精密度试验的RSD(n=6)均＜2.0％.并将该法应用于银杏总黄酮醇苷的饱和溶解度的测定.该法灵敏、准确、重复性好,结合透析法可以准确的测定EGBN中黄酮、萜类内酯的含量,适合于银杏叶提取物类脂质体的质量控制.     

响应面法优化芹菜汁内酯豆腐生产工艺

以大豆和芹菜为原料,以葡萄糖酸-δ-内酯（GDL）为凝固剂制作芹菜汁内酯豆腐,综合运用感官评定和质构测定的方法对芹菜汁内酯豆腐的感官品质和质构特性进行了分析,确定制作芹菜汁内酯豆腐的最适单因素条件,再利用响应面分析法确定芹菜内酯豆腐的最佳工艺条件为：GDL添加量0.33%,芹菜汁添加量19%,凝固温度78 ℃,凝固时间30 min,此工艺下制作出的芹菜汁内酯豆腐呈浅绿色,口感细腻有弹性,质地柔软有光泽,既有纯正的豆香味又有芹菜特有的风味。     

Prevalence of anthelmintic resistance on 62 beef cattle farms in the North Island of New Zealand

AIM: To establish the prevalence of anthelmintic resistance in parasitic nematodes on a random sample of beef cattle herds in the North Island of New Zealand.

METHODS: A cross-sectional prevalence study was conducted using a standardised faecal nematode egg count (FEC) reduction (FECR) test (FECRT) for ivermectin, levamisole and albendazole on 60 calves on each of 62 farms in the North Island chosen at random from farms that conformed with the selection criteria. Resistance to an anthelmintic was inferred when there was <95% reduction in FEC 7-10 days after treatment. Larval cultures were performed for all control groups and for treated groups for which resistance was evident.

RESULTS: Of the farms that completed the FECRT, 4/61 (7%) showed ≥95% reduction in FEC for all anthelmintics tested. Resistance to ivermectin was evident on 56/61 (92%) farms, to albendazole on 47/62 (76%) farms, and to both ivermectin and albendazole on 45/61 (74%) farms. Resistance to levamisole was evident on only 4/62 (6%) farms. The parasites most prevalent in resistant populations cultured were Cooperia spp. On 45/61 (74%) farms where Cooperia spp were present in suffi cient numbers, resistance to both ivermectin and albendazole was evident. No cases of levamisole-resistant Cooperia spp were detected. Resistance of Ostertagia spp to ivermectin was evident on 4/45 (9%) farms, to albendazole on 15/46 (35%) farms, and to levamisole on 4/46 (9%) farms.

CONCLUSION: Anthelmintic resistance in parasitic nematodes of cattle is common in the North Island of New Zealand. Beef farmers need to be aware of the risks posed by anthelmintic resistance, and routine FECR testing is recommended to ensure optimal productivity and to guide decision-making when purchasing anthelmintics to be used on-farm.     

Turbulence and change - the veterinary profession in a competitive environment

This paper examines the views of members of the veterinary profession towards the change in orientation of professional practice that is occurring. It contrasts the values of veterinarians with those of doctors, dentists, lawyers and accountants. Particular attention is given to the areas of business efficiency, competition and advertising.

Data was derived from self-completion questionnaires containing 40 Likert scales which were mailed to 300 members of each of the five professions.     

Protozoan encephalomyelitis causing pelvic limb paresis in a yearling sheep

A pelvic limb paresis of 6 weeks duration in a yearling sheep resulted from protozoan encephalomyelitis involving the spinal cord at the thoracolumbar junction. An elevated lumbosacral cerebrospinal fluid protein concentration but normal cisternal cerebrospinal fluid protein concentration indicated the presence of a thoracolumbar inflammatory lesion resulting in cord compression which obstructed the rostral flow of the cerebrospinal fluid. Under general anaesthesia, myelography at the lumbo-sacral site demonstrated blockage to the rostral flow of contrast medium at T₁₃L₁. At necropsy, there were no gross pathological changes at T₁₃/L₁, but histopathology revealed non-tract specific lymphocytic perivascular cuffing, axonal swelling and oedema in the spinal cord, characteristic of a protozoa1 encephalomyelitis. No parasites were detected in the multiple spinal cord sections examined but immunocytochemistry identified antigens cross-reactive with Sarcocystis spp. antigens in glial cells in these lesions.     

Farm management practices associated with macrocyclic lactone resistance on sheep farms in New Zealand

AIM: To identify farm practices associated with the presence of resistance to a macrocyclic lactone (ML) anthelmintic on sheep farms in New Zealand.

METHODS: A cross-sectional study was conducted to test for associations between the presence of resistance to an ML anthelmintic (ivermectin) and management practices on sheep farms in New Zealand. Selection of farms was both random (n=80) and purposive (n=32; being farms with a history of suspected ML resistance). Resistance was inferred from faecal nematode egg count (FEC) reduction (FECR) tests (FECRTs) when there was <95% reduction in FEC 7–10 days after treatment with a half dose of ivermectin (0.1 mg/kg). A logistic regression model was built to identify farm-level factors that were associated with the presence or absence of ML resistance.

RESULTS: Of the 112 flock managers that were approached for interview, 103 (92%) returned useable questionnaires. The odds of ML resistance were increased: on farms that had used long-acting ML products in ewes as a pre-lambing treatment for ≥3 of the previous 5 years (odds ratio (OR) = 7.2; 95% confidence interval (CI) = 1.7–30.3); on farms where <70% of the total stock units mid-winter were from sheep (OR=6.5; 95% CI=1.6–25.6); on farms which over the year purchased ≥10% of the number of sheep present mid-winter (OR=7.1; 95% CI=1.5–34.7); and on farms where the average wool diameter of the main flock was <37 (OR=4.1; 95% CI=1.1–14.7) microns. The model provided a good fit to the data (pseudo R²=0.64; Hosmer-Lemeshow statistic = 0.38).

CONCLUSIONS: Explanatory factors identified as associated with the presence of ML (ivermectin) resistance on farms included the use of long-acting anthelmintic formulations in ewes pre-lambing, sources of refugia of unselected parasites on the farm, breed of sheep and their requirements for anthelmintic treatments, and the importing of resistant parasites with purchased stock. The study provides support for controls that aim to provide refugia of susceptible worms and that minimise the risk of introduction of resistance through effective quarantine-drenching.     

大环内酯类抗寄生虫药耐药性研究进展

近年来,世界各国陆续报道了寄生虫对大环内酯类抗寄生虫药物的耐药性。影响这类药物耐药性产生和发展的因素很多,包括药物的结构、性质、药物选择压力、耐药基因的遗传特性、用药频率、用药时机、治疗效果以及用药剂量等。谷氨酸门控氯离子通道亚基构象的突变,是引起寄生虫对依赖其作用的药物产生耐药的主要原因。但是,这类药物的耐药机制比较复杂,还存在着γ-氨基丁酸门控氯离子通道受体结构改变引起的耐药以及P-糖蛋白基因结构改变引起的耐药。     

Sesquiterpene lactones from Carpesium abrotanoides

Phytochemical study on the ethanol extract of the aerial parts of Carpesium abrotanoides led to the isolation of two new sesquiterpene lactones, carabrolactone A (1) and carabrolactone B (2). Their structures were elucidated on the basis of extensive spectroscopic analysis.