Population variability in animal health: Influence on dose‐exposure‐response relationships: Part II: Modelling and simulation

During the 2017 Biennial meeting, the American Academy of Veterinary Pharmacology and Therapeutics hosted a 1‐day session on the influence of population variability on dose‐exposure‐response relationships. In Part I, we highlighted some of the sources of population variability. Part II provides a summary of discussions on modelling and simulation tools that utilize existing pharmacokinetic data, can integrate drug physicochemical characteristics with species physiological characteristics and dosing information or that combine observed with predicted and in vitro information to explore and describe sources of variability that may influence the safe and effective use of veterinary pharmaceuticals.     

Population variability in animal health: Influence on dose–exposure–response relationships: Part I: Drug metabolism and transporter systems

There is an increasing effort to understand the many sources of population variability that can influence drug absorption, metabolism, disposition, and clearance in veterinary species. This growing interest reflects the recognition that this diversity can influence dose–exposure–response relationships and can affect the drug residues present in the edible tissues of food‐producing animals. To appreciate the pharmacokinetic diversity that may exist across a population of potential drug product recipients, both endogenous and exogenous variables need to be considered. The American Academy of Veterinary Pharmacology and Therapeutics hosted a 1‐day session during the 2017 Biennial meeting to explore the sources of population variability recognized to impact veterinary medicine. The following review highlights the information shared during that session. In Part I of this workshop report, we consider sources of population variability associated with drug metabolism and membrane transport. Part II of this report highlights the use of modeling and simulation to support an appreciation of the variability in dose–exposure–response relationships.     

广西地方玉米种质和加拿大群体的遗传多样性分析

 【目的】分析45份广西地方玉米品种和15份加拿大改良群体的遗传多样性,为更好地利用地方品种拓宽广西玉米种质的遗传基础提供理论依据。【方法】采用混合取样法（每个群体中随机提取4个混合样本,每个样本包括10个单株）和SSR分子标记技术进行研究。【结果】70对SSR引物在60个群体的240份样本中扩增出245条等位基因,每对引物检测出的等位基因数目为2～6条,平均每个位点3.5条。加拿大的15份群体和广西的45份地方品种分别聚为二大类群。加拿大的15份群体又可以分为硬粒型和马齿型两个亚群。在45份广西地方种质中,同样可以分为硬粒型和马齿型两个亚群;糯玉米没有单独聚类,而是分散在硬粒型类群当中。【结论】广西亚热带种质比温带的加拿大种质具有更大的遗传变异,研究这些材料的遗传多样性可更好地扩增广西玉米种质的遗传基础,对玉米育种中发现潜在突破性种质可能会起到一定的作用。     

Development of drought‐tolerant breeding lines derived from Helianthus annuus × H. argophyllus interspecific crosses

Helianthus argophyllus is a wild species known as “silver sunflower”, which possesses several traits, including morphological traits that increase drought tolerance. Therefore, introgressions between chosen cultivated lines and two H. argophyllus accessions were made, and segregating generations were established. Important agronomic traits including single heading, high pollen fertility, silver canopy (indicating more cuticular wax), and content of cuticular waxes and oil were selected over six segregating generations. The resulting F₆ lines showed introgression of water saving traits, as they had lower excise leaf water loss, with comparable yield to standard checks. However, these F₆ lines were late maturing and showed poor flowering synchronization between the cultivated and introgressed lines. Introgressed line “D‐22” was particularly promising as a breeding line, with superior agronomic and drought resistance traits. This line had the potential to be used as an inbred parental line for introgression of drought resistance traits into elite sunflower germplasm. Combining ability analysis of the introgressed lines further showed their potential for heterosis breeding or to be used as parental lines in breeding programme.     

Responsiveness of fish mass–abundance relationships and trophic metrics to flood disturbance,stream size,land cover and predator taxa presence in headwater streams

Characterisation of food webs, by summarising energy transfer and trophic relationships, allows more functional measurement of ecosystems and may reveal threats (e.g., land‐cover change) in sensitive environments that are not obvious from conventional biomonitoring. However, typical methods used to achieve this are time‐consuming and expensive. Therefore, we tested the usefulness of fish‐focused food‐web proxies as functional measures, specifically mass–abundance relationships of fish assemblages and stable isotope (SI)‐derived metrics in headwater stream reaches. These metrics have been trialled before for similar use in other settings, but have yielded varying results, and have not been employed in tandem in temperate freshwaters. Sampling reaches (N = 46) were spread across a variety of streams, and the effects of habitat predictors at multiple scales on metrics were assessed using model selection. We found that habitat size positively correlated with food‐chain lengths in streams, possibly because of increased abundance of fish at multiple trophic levels in habitats with more space. Additionally, flood disturbance was negatively associated with fish mass–abundance and carbon range, likely due to the harshness of flood‐prone streams. Riparian land‐cover variables were correlated with multiple metrics, indicating the importance of terrestrial–aquatic linkages. Additionally, variations in all metrics were influenced by the presence of native, predatory longfin eels. Overall, we conclude that mass–abundance relationships and SI‐derived metrics are sensitive to drivers of trophic organisation and likely reflect processes occurring at multiple spatial scales in freshwaters. Thus, these metrics could be an insightful monitoring tool for managers because they reflect functional measures of aquatic ecosystems.     

Farmers' perceptions and practices for managing tomato leaf curl virus disease in southern India

A survey of 174 tomato farmers in five districts of Karnataka State, South India, was conducted between March and July 1998 with the objectives of assessing farmers' knowledge and perceptions of tomato leaf curl virus disease (ToLCVD) and examining their current control practices. The findings showed that farmers were familiar with ToLCVD and regarded it as a serious constraint upon production, particularly in the hot season. However, only 2% of farmers were aware that tomato leaf curl virus (ToLCV) was transmitted by a whitefly vector, Bemisia tabaci . A similarly small number of farmers knew that ToLCVD was caused by a virus, whilst 86% of farmers believed that it was caused by high temperatures. Approximately 90% of farmers relied primarily on pesticides for control of ToLCVD. Few ToLCV-resistant varieties were available but one such variety, Avinash II, was grown by 13% of farmers in the hot season when incidence of the disease is highest. Farmers visiting experimental trials at a farmer field day, showed a strong interest in new advanced breeding tomato lines with resistance to ToLCV. Factors affecting the adoption of ToLCV-resistant varieties by tomato farmers are discussed.     

A comparison of the effectiveness of three neck-hold killing traps in occluding carotid arteries in the neck of the brushtail possum

Aims. To compare the potential humaneness of three types of neck-hold killing traps in terms of the blood vessels that are occluded, and to examine the anatomy of the blood vessels that supply blood to the possum’s brain.

Method. The prevalence of occlusion of the common carotid arteries and the trachea was examined in 33 possums which were caught with Timms, LDL and Conibear 160 traps. The anatomy of the blood supply to the brain was examined in six possums using a resin casting technique.

Results. The prevalence of complete bilateral common carotid artery occlusion was 77% for the Timms trap, 45% for the LDL trap and 22% for the Conibear 160 trap. The major route for blood supply to the brain was via the common carotid arteries.

Conclusion. Where the aim is to kill possums quickly by ischaemia of the brain, the Timms trap is to be preferred over the LDL and Conibear 160 traps.     

Marker-Assisted Introgression of Quantitative Resistance Gene pi21 Confers Broad Spectrum Resistance to Rice Blast

The quantitative resistance gene pi21 from Sensho was introgressed to an indica breeding line IR63307-4B-13-2, a pyramiding line IRBB4/5/13/21, and a tropical japonica line Kinandang Patong by marker-assisted backcrossing. A total of 192 improved lines at the BC_4F_3 and BC_4F_4 generations were developed and confirmed to have the gene introgression via genotyping using a pi21-specific In Del marker. Thirteen randomly selected improved lines, representing all the three genetic backgrounds, demonstrated resistance against leaf blast composites in the field and a broader spectrum resistance against individual isolates compared to the recurrent parents in the glasshouse. Specifically, the tested lines exhibited pi21-acquired resistance against 11 leaf blast isolates that elicited susceptible reactions from the recurrent parents. All the tested lines maintained a comparative heading date, and similar or improved panicle length, number of primary branches per panicle and number of total grains per panicle relative to the recurrent parents. The physical grain characteristics of the recurrent parents were also maintained in the 13 lines tested, although variability in the amylose content and chalkiness degree was observed. The successful marker-assisted introgression of pi21 in diverse genetic backgrounds and the resulting broader spectrum resistance of improved lines against leaf blast indicate the potential of pi21 for deployment in cultivars grown across other rice growing regions in Asia.     

Gallbladder sludge on ultrasound is predictive of increased liver enzymes and total bilirubin in cats

The purposes of this retrospective study were to assess the prevalence of gallbladder sludge (GBS) in a population of cats presented for abdominal ultrasound in a teaching hospital and to determine its association with increased serum alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total bilirubin (TB). Gallbladder sludge was detected in 152 (14%) of the cats undergoing abdominal ultrasound between 2004 and 2008. This population was compared to a control group of 32 cats without GBS. Alanine aminotransferase, ALP, and TB mean values were significantly higher in cats with GBS than in controls (P ≤ 0.0005) and odds for increased values in cats with GBS were 4.2 [95% confidence interval (CI): 1.6 to 11.0], 9.5 (95% CI: 2.2 to 41.7), and 4.1 (95% CI: 1.5 to 11.5), respectively (P ≤ 0.007). In conclusion, GBS is an uncommon ultrasonographic finding in cats that is predictive of increased liver enzymes and TB. More studies are needed to establish potential links between GBS and hepatobiliary disease in cats.