Dynamics of the response of barley mildew to the use of sterol synthesis inhibitors1

Since 1980, the increase in the use of triazole fungicides to control Erysiphe graminis on barley in the UK has been accompanied by an increase in the frequency of pathogen isolates with different levels of reduced sensitivity to the fungicides. In each year, the rate of change varied, probably in relation to the degree of selection at different times in the host life cycle. In the first years, isolates with reduced sensitivity were less pathogenic than sensitive strains on a range of host cultivars. These differences were less obvious on cultivars with the Mla6 and Mlv resistance genes. More recently, reduced sensitivity has become widespread in the pathogen population and the general pathogenicity of this part of the population has increased. As a result, the yield benefit previously associated with mildew control by the triazoles is becoming severely diminished. This effect is not due primarily to the increase of highly insensitive isolates, but to the high frequency of isolates with intermediate insensitivity that are able to cause epidemic increase of the pathogen soon after fungicide application.     

Host-mediated interactions between pathogen genotypes

Barley c ltivars with different resistance genes were inoculated with various sequences of virulent and non-virulent isolates of Erysiphe graminis f.sp. hordei. The resistance induced in incompatible reactions decreased infection by virulent isolates while, conversely, the degree of susceptibility induced in compatible reactions was sufficient to increase the ability of normally non-virulent isolates to infect a resistant host. The net effect of interactions was always overall reduction of conidial production when compared with inoculation of a virulent isolate alone.
Each interaction between isolates was dependent on the host cultivar, the pathogen isolates used and on the inoculation sequence. Often, induced resistance was most obvious when a nonvirulent isolate was inoculated prior to a virulent isolate. Induced susceptibility was usually more apparent when the virulent isolate was inoculated first. However, on the cultivar Wing, induced susceptibility was more apparent following prior inoculation of a non-virulent isolate. On the cultivar Hassan, prior inoculation with a virulent isolate sometimes induced susceptibility, but in some cases more susceptibility was induced by prior inoculation with a non-virulent isolate. In the latter instances, although relatively little infection developed, the majority of the spores produced were those of the normally non-virulent isolate.
There was some evidence of non-virulent isolates acquiring the ability to infect normally incompatible hosts. This effect disappeared after several generations in the absence of the virulent isolate.     

Integration of host resistance and fungicide use1

The current strategies for using host resistances and fungicides encourage the increase of pathogen strains with matching pathogenicity or insensitivity. Diversification of cultivars and fungicides is recommended, but involves only diversification between crops and does not include integration of the two methods of control. A strategy of complete or total diversification requires diversification within as well as between crops. For example, the system of using cultivar mixtures can provide assured high yields, even though control of pathogen development is incomplete. Within-crop diversification of fungicides applied to seed is becoming a practical possibility with the development of film-coating of carriers that can adhere different materials firmly to different seeds whilst maintaining uniform seed-flow characteristics. An ideal system would involve integrated total diversification of host cultivars and fungicides. Field data indicate that this can provide excellent profit margins and disease control, while maximising evolutionary problems for the pathogen. The system is technically feasible using developed methods of cultivar mixing together with the new technique of film-coating.     

Long term use of hydraulic artificial urethral sphincters in nine dogs from New Zealand with urethral sphincter mechanism incompetence

AIMS: To report on the long-term outcomes of hydraulic artificial urethral sphincter (HAUS) placement for the correction of urethral sphincter mechanism incompetence (USMI) in New Zealand dogs.

METHODS: Retrospective data were obtained from cases of dogs which had a HAUS placed after failed medical and/or surgical management of USMI between August 2012 and November 2016. Owner assessment of urinary incontinence was evaluated by an online survey in May 2017 using a visual analogue scale (0 being normal, 100 being severely affected) for the frequency, volume and severity of any straining to urinate, immediately prior to the placement of the HAUS and at the time of the survey. The number of days between surgery and the completion of survey were recorded.

RESULTS: Seven females and two male dogs, which were all desexed except for one female, were eligible for inclusion in the study. The period of follow-up following HAUS placement ranged from 206–1,685 days. Following HAUS placement, frequency and volume of urinary incontinence decreased for six dogs and were practically unchanged for three dogs. The median frequency score decreased from 70 to 13 and the volume score decreased from 73 to 12. There was no consistent change in the perceived degree of straining to urinate. Complications occurred in three dogs; one required repositioning of a dislodged injection port, one required management for haematuria and a hypoplastic bladder, and one required surgical removal of fibrous tissue around the HAUS cuff.

CONCLUSIONS AND CLINICAL RELEVENCE: HAUS placement was an effective method for the treatment of persistent USMI in most dogs and provided good clinical results based on owner assessment. The technique was associated with few complications and allowed successful long-term control of urinary incontinence without the need for medical management.     

"人、机、料、法、环"与兽药GMP的关系

本文尝试将质量管理学中五要素"人、机、料、法、环"的重要概念引入到兽药GMP管理体系中来,便于记忆和理解,有助于进一步认识、掌握和运行GMP.     

对兽药地方标准清理工作的思考

当前兽药地方标准清理工作已进入攻关阶段,但在清理地方标准的实际工作中尚存在一些问题,笔者分析了这些具体问题,认为在升标工作中,政府应当给予合理的政策扶持,加快地方标准清理工作进度,保护企业利益;企业应当着重做好品种筛选,合理安排临床试验资金投入;企业通过采取联合参与升标方式,减少资金投入;对于移植外省标准,可采取不同措施妥善解决;为保证升标工作顺利进行,农业部和各省兽医行政管理部门应做好升标培训指导工作.     

Pathology of experimental enteric septicaemia in channel catfish, Ictalurus punctatus (Rafinesque), following immersion-exposure to Edwardsiella ictaluri

Abstract. Fingerling channel catfish, Ictalurus punctatus (Rafinesque), were exposed experimentally to Edwardsiella ictaluri by immersion for 1 h in water containing 5 × 10⁸ colony-forming units (CFU) of the bacterium per ml. Ninety per cent of the fish developed lesions typical of enteric septicaemia of catfish (ESC), 93% of affected fish developed the acute form of ESC and 7% developed chronic ESC. Acute disease was characterized grossly by cutaneous haemorrhage and ulceration, and microscopically by enteritis, olfactory sacculitis, hepatitis and dermatitis. The earliest lesions of acute ESC, i.e. enteritis and olfactory sacculitis, were observed microscopically at 2 days post-exposure (PE); gross lesions, primarily mild subcutaneous haemorrhage at the base of fins, were first apparent at 4 days PE. Chronic ESC, seen most commonly 3–4 weeks PE, was characterized by dorsocranial swelling and ulceration, granulomatous olfactory neuritis/perineuritis, and meningoencephalitis involving the olfactory bulbs, olfactory tracts and olfactory lobes of the brain. Gross and microscopic lesions in the acute and chronic forms of experimental ESC were similar to the lesions reported in naturally occurring ESC. Definitive pathogenesis of acute and chronic ESC remains to be determined.     

江苏省兽药科技创新探析

当前兽药生产企业已全面通过GMP验收，兽药科技创新成为后GMP时代企业生存发展的首要任务。在此形势下江苏省提出了“建设兽药强省”工作思路。针对当前江苏乃至全国兽药产业现状进行了调查分析和研究探索，就如何充分利用本省科研优势和GMP建设形成的基础设施优势，在政府投入引导机制、合作创新开发机制和企业内研发机制等方面提出了建设性意见。