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1.
BACKGROUND: Screening tests for feline retroviruses are thought to have high sensitivity and specificity, although previous studies that evaluated these tests have limitations. Novel statistical approaches have been developed that allow the estimation of sensitivity and specificity in situations where the true state of the disease in individual animals cannot be assured. OBJECTIVE: The purpose of this study was to evaluate the sensitivity and specificity of a variety of retrovirus tests, including some screening tests, in a population of cats potentially infected with either feline leukemia virus (FeLV) and/or feline immunodeficiency virus (FIV) by using a Bayesian statistical approach. METHODS: Four hundred and ninety blood samples from cats being evaluated for FIV infection were tested by 2 rapid immunomigration tests (Witness single [WS], Witness combi [WC]) and a plate-based ELISA (Petcheck) for FIV antibody, and by a newly designed real-time polymerase chain reaction (PCR) assay for FIV provirus. Four hundred and ninety-five blood samples from cats being evaluated for FeLV infection were tested by 2 rapid immunomigration tests (WS, WC) and a plate-based ELISA (Petcheck) for FeLV antigen, and by a FeLV virus isolation technique. Results were then analyzed by using a Bayesian statistical method. RESULTS: For FIV tests, median sensitivity estimates were 0.98 for WS, 0.97 for WC, 0.98 for ELISA, and 0.92 for PCR. Median specificity estimates were 0.96 for WS, 0.96 for WC, 0.93 for ELISA, and 0.99 for PCR. For FeLV tests, median sensitivity estimates were 0.97 for WS, 0.97 for WC, 0.98 for ELISA, and 0.91 for virus isolation. Median specificity estimates were 0.96 for WS, 0.96 for WC, 0.98 for ELISA, and 0.99 for virus isolation. CONCLUSIONS: The use of Bayesian statistical methods overcomes a variety of methodologic problems associated with diagnostic test evaluations, including the lack of a definitive reference test. The sensitivity and the specificity of all 6 evaluated screening tests was high: however, specificity estimates were slightly lower than those reported by most recent studies.  相似文献   

2.
The construction of ancillary equipment used to improve image quality and reduce personnel radiation exposure in the equine nuclear medicine laboratory is illustrated. The devices include a self supporting lead sheet for shielding the distal limb or limb pair, a hanging lead sheet for shielding the proximal limb, a lead square for shielding the urinary bladder or jugular catheter, a restraining board for acquiring a palmar view of the foot, a head support to stabilize the head for imaging and a head support for stabilizing the neck for imaging. The restraining board and head supports decrease patient motion, improve image quality, and decrease the number of repeat acquisitions so that the time to perform the complete study is shortened. The self supporting shielding device allows the handlers to increase their distance from the horse which enhances radiation safety.  相似文献   

3.
Genetic parameters were estimated for prevalences of primary cataract (CAT), persistent pupillary membrane (PPM) and distichiasis (DIST) in 615 single-colored and 617 multi-colored English Cocker Spaniels (ECS) bred in the German kennel club for Spaniels (Jagdspaniel-Klub e.V.). CAT or CAT diagnosed in dogs up to three and a half years of age (early-onset cataract, CAT-early) and CAT diagnosed in dogs over three and a half years of age (late-onset cataract, CAT-late), PPM and DIST were included as binary traits in multivariate genetic analyses. Heritabilities on the underlying liability scale were 0.15 for CAT, 0.34 for CAT-early, 0.13 for CAT-late, 0.46 for PPM, and 0.62 for DIST in single-colored ECS and 0.06 for CAT, 0.13 for CAT-early, 0.14 for CAT-late, 0.10 for PPM, and 0.61 for DIST in multi-colored ECS. There were indications for a different genetic basis of CAT-early and CAT-late in single-colored ECS as genetic correlations were close to zero. In multi-colored ECS, a similar tendency for CAT-early and CAT-late could be observed.  相似文献   

4.
The aim of this study was to investigate the need for different cut-off points, according to animal age and the purpose of testing, for two of the most widely used serological techniques in bovine neosporosis, IFAT and a crude antigen ELISA (Civtest, HIPRA). Therefore, the population reference sera used were defined using a combination of multiple criteria such as epidemiological/clinical and histopathological parameters and an immunoblot test. Firstly, foetuses and breeding cattle (heifers and cows) were considered as separate subpopulations for serological evaluation. Secondly, cut-off points for each serological technique (IFAT and ELISA) according to age group (foetuses and breeding cattle) and the different practical applications (detection of infection and abortion) were calculated following the receiver operating characteristics (ROC) analysis. Cut-off points were defined, for IFAT and ELISA for aborted breeding cattle and for IFAT alone in the case of the foetuses, assuming an equivalent cost of false positive and negative results. In infected breeding cattle, for IFAT and ELISA and in foetuses for ELISA, two possible cut-off values were obtained, one for a maximum sensitivity and one for a maximum specificity and the intervals of unclear results were defined. In this case, a cut-off value for equal sensitivity and specificity was also estimated. When cut-off points for infected breeding cattle, 1:100-1:250 for IFAT and 0.306-0.451 for ELISA were applied to a target population, optimal and similar negative and positive predictive values together with similar apparent and true prevalence results were observed suggesting the possibility of using both tests interchangeably.  相似文献   

5.
本研究欲通过改进数据存取方式、增加矩阵运算以提高雪灾监测与预警系统对数据的更新效率和对矩阵的处理能力。使用Tomcat Web服务、GeoServer地图服务、PostgreSQL数据库、OpenLayers地图数据访问框架、J2EE技术架构、雪灾风险评估Logistic线性回归模型、雪灾家畜死亡率估测BP-ANN模型以及MATLAB矩阵运算功能设计开发青海省牧区雪灾监测与预警系统,以实现雪灾监测与预警数据、区域属性信息的web页面展示及查询,雪灾风险概率运算,雪灾家畜死亡率运算以及数据导入等功能,解决以往雪灾风险监测系统对数据资料更新不及时的问题,提高风险监测与预警系统的矩阵运算能力,同时减少重复的数据操作,方便用户对青海省牧区雪灾监测及预警数据的管理。  相似文献   

6.
In recent decades, electrical conductivity (EC) has been introduced as an indicator of mastitis, and genetic selection based on this trait may be possible. In this study, genetic parameters for test-day EC and test-day somatic cell score (SCS) were compared. Data were collected from a Danish experimental herd, including daily records of EC and SCS from 265 first lactation cows. Different genetic models were tested, and a random regression animal model with a 4th order Legendre polynomial for the permanent environmental effect for both traits, a 1st order Legendre polynomial for the additive genetic effect of EC and a 2nd order Legendre polynomial for the additive genetic effect of SCS, gave the best fit. The patterns of the curves were similar for both permanent environmental and additive genetic variance for the two traits. Heritability estimates ranged from 0.05 to 0.12, and from 0.01 to 0.09, for EC and SCS, respectively. The estimate of genetic correlation between the traits was high, and ranged from 0.86 to 0.98. Based on these results, EC could be a potential indicator trait in a breeding programme where selection for increased mastitis resistance is included.  相似文献   

7.
WANG Yang  JIN Yi 《中国畜牧兽医》2017,44(5):1281-1288
Small interfering RNA (siRNA) has proved to be a powerful tool for target-specific gene silencing via RNA interference (RNAi). Its ability to control targeted gene expression gives new hope to gene therapy as a treatment for cancers and genetic diseases. However,siRNA shows poor pharmacological properties, such as low serum stability,off-targeting, and innate immune responses, which present a significant challenge for clinical applications.In addition, siRNA cannot cross the cell membrane for siRNA activity because of its anionic property and stiff structure.Therefore, the development of a safe,stable,and efficient system for the delivery of siRNA therapeutics into the cytoplasm of targeted cells is crucial. Several nanoparticle platforms for siRNA delivery have been developed to overcome the major hurdles facing the therapeutic uses of siRNA. This review covers a broad spectrum of non-viral siRNA delivery systems developed for enhanced cellular uptake and targeted gene silencing in vitro and in vivo, and discusses their characteristics and opportunities for clinical applications of therapeutic siRNA,in order to lay a good foundation for the later research.  相似文献   

8.
王洋  金一 《中国畜牧兽医》2017,44(5):1281-1288
小干扰RNA （small interfering RNA,siRNA）通过基因干扰技术进行有针对性的基因沉默,其控制目标基因表达的能力为基因治疗癌症和遗传性疾病提供了新的希望。但siRNA的药理性能很低,如血清稳定性低、脱靶、先天免疫反应,为临床治疗提供了一个挑战。由于负离子性能和刚性结构致使siRNA难以穿透细胞膜,因此,构建安全、稳定、高效的siRNA运载系统将siRNA运载到靶细胞的细胞质是至关重要的。作者综述了几种可增强体内外细胞摄取和靶基因沉默的广泛、发达的非病毒性siRNA运载系统,并讨论了它们的特点和进行siRNA治疗用于临床应用的机会,以期为今后siRNA的研究与临床应用奠定基础。  相似文献   

9.
The objective of this study was to determine an appropriate method for using yearling scrotal circumference observations and heifer pregnancy observations to produce EPD for heifer pregnancy. We determined the additive genetic effects of and relationship between scrotal circumference and heifer pregnancy for a herd of Hereford cattle in Solano, New Mexico. The binary trait of heifer pregnancy was defined as the probability of a heifer conceiving and remaining pregnant to 120 d, given that she was exposed at breeding. Estimates of heritability for heifer pregnancy and scrotal circumference were .138+/-.08 and .714+/-.132, respectively. Estimates of fixed effects for age of dam and age were significant for heifer pregnancy and bull scrotal circumference. The estimate of the additive genetic correlation between yearling heifer pregnancy and yearling bull scrotal circumference was .002+/-.45. Additional analyses included models with additive genetic groups for scrotal circumference EPD for heifer pregnancy or heifer pregnancy EPD for scrotal circumference to account for a potential nonlinear relationship between scrotal circumference and heifer pregnancy. Results support the development of a heifer pregnancy EPD because of a higher estimated heritability than previously reported. The development of a heifer pregnancy EPD would be an additional method for improving genetic merit for heifer fertility.  相似文献   

10.
A total of six AVA members have formally nominated for the two positions to be contested in the coming election to choose a President-Elect and a member of the AVA Board. There are three candidates for President-Elect and four for the Board position (one nominee has chosen to contest both ballots). The candidates for President-Elect are: Tom Lonsdale, Norm Blackman and Ian Denney (a member of the current Board). The nominees for the Board are: Norm Blackman, Joanne Sillence, Breck Muir and Robert Baker. Each of the nominees was requested to submit a 200 to 300* word'biography for publication in this edition of the AVJ (see below) as a means of indicating to members why they are seeking support for the positions they are contesting.  相似文献   

11.
The purpose of this study was to compare characteristics and performances between single-phase (SP) and high-frequency (HF) generators for x-ray units dedicated to veterinary radiology practice. A 30-kW SP and a 30-kW high HF generator connected to a rotating anode x-ray tube were used for the study. Source-film distance, screen/film combination, and film processing were kept the same during the experiment. The mAs value yielding a similar film optical density of a stair step phantom, as assessed by a densitometer and a similar dose, as assessed by a solid state detector, was estimated for different kVp values. The ratio of the mAs used with the SP generator to the equivalent mAs used with the HF generator to produce similar film density or radiation dose was calculated. Subject contrast was measured for different kVp values as the relative difference in film optical density between two steps of the phantom. The waveform of the tube current was recorded for the two generators using an oscilloscope. Motion artifact was produced on a lateral radiograph of a canine tarsus using the two generators. Reproducibility was assessed by comparing the variances of film density measurements made on the central step of the phantom on 10 consecutive images produced with the two generators. mAs ratios (SP/HF) to obtain similar film optical density ranged from 2 (for 90kVp) to 2.5 (for 70 kVp), and mAs ratios to obtain similar radiation dose ranged from 1.2 (for 100 kVp) to 1.4 (for 70 kVp). Image contrast was slightly higher for the SP than for the HF generator. Current waveform for the SP generator was half-sinusoidal and it was almost continuous for the HF generator. Motion artifact appeared as blur for the HF generator and as several regularly placed images of the subject for the SP generator. Reproducibility was significantly better for the HF than for the SP generator (P = 0.047). It was concluded that the HF generator was approximately two times more efficient, had a better reproducibility, and produced images with a lower contrast than the SP generator. Motion artifact appears differently due to different current waveform.  相似文献   

12.
文章以云贵高原的人工草地为研究对象，分析了草地资源分布的时空特征及增长动态，运用生物控制论方法组建了牧草资源种群保护性利用的最大持续产量模型，并以试验为例，确定了具体的保护指标与放牧管理措施，研究了单播人工草地的最优控制模型与放牧对策，进行了相应的定量分析。  相似文献   

13.
Advances in the understanding of protective immune responses to tuberculosis are providing opportunities for the rational development of improved vaccines for bovine tuberculosis. Protection requires activation of macrophages through stimulation of a Th 1 type immune response. Ideally, a vaccine for cattle should induce protection without causing animals to react in a tuberculin test when exposed to Mycobacterium bovis. A number of new tuberculosis vaccines including attenuated M. bovis strains, killed mycobacteria, protein and DNA vaccines have been developed and many of these are being assessed in cattle. The requirements for a tuberculosis vaccine for wildlife differ from those for cattle. The major goal of a wildlife vaccine is to prevent the transmission of M. bovis to cattle and other wildlife. Although there are a number of technical problems associated with the development of a vaccine delivery system for wildlife, attenuated M. bovis vaccines administered via oral baits or aerosol spray to possums have already been shown to reduce the severity of a subsequent M. bovis infection.  相似文献   

14.
《Veterinary microbiology》2015,175(2-4):179-184
Sunshine virus is a paramyxovirus of pythons associated with neurorespiratory disease and mortalities. This report provides evidence for its vertical transmission. In a collection of over 200 Australian pythons, a dam and a sire, both carpet pythons (Morelia spilota), were PCR-positive for Sunshine virus at a time when the dam was likely to have been gravid. A clutch of 21 eggs was laid and three non-viable eggs were tested for the presence of Sunshine virus by PCR. One egg had been incubating for 34 days while the other two had been incubating for 49 days. The surface of all three eggs was negative for Sunshine virus but swabs of the allantois and amnion were positive in all three eggs. Embryo tissue samples were tested from the two 49 day old eggs. From one embryo, a sample of brain and a pooled sample of lung, liver, kidney and intestine were positive, while for the other embryo, a pooled sample of lung, liver, kidney, intestine and brain was positive. Fourteen of the 21 eggs hatched and all hatchlings were tested by PCR at least once between the ages of 53 and 229 days old. All hatchlings were PCR-negative for Sunshine virus.  相似文献   

15.
Typing of Haemophilus parasuis strains by PCR-RFLP analysis of the tbpA gene   总被引：13，自引：0，他引：13  
On the basis of a species-specific PCR assay, a RFLP analysis for typing of Haemophilus parasuis strains was developed and evaluated. Amplification was based on the gene tbpA, encoding a transferrin-binding protein. RFLP analysis of the 1.9-kb tbpA-amplicon using TaqI, AvaI and RsaI endonucleases produced 12 different patterns for the reference strains of the 15 known H. parasuis serovars, and showed a high heterogeneity (33 RFLP groups) for 101 H. parasuis clinical isolates tested. The sensitivity, typeability (100% versus 65% for immunodiffusion), high degree of discrimination (0.93 versus 0.84 for immunodiffusion), simplicity and low cost per test make this PCR-RFLP assay a useful method for typing H. parasuis and, therefore, for studying the epidemiology of outbreaks of Gl?sser's disease.  相似文献   

16.
Between 0 and 50 per cent of the dogs in eight rural villages in far northern California with a high risk of tickborne diseases were seropositive for Anaplasma phagocytophilum and Bartonella vinsonii subspecies berkhoffii, and between 0 and 10 per cent were seropositive for Borrelia burgdorferi. The odds ratio for the co-exposure of individual dogs to B vinsonii berkhoffii and A phagocytophilum was 18.2. None of the diseases was associated with the sex of the dogs, whether they slept out of doors, or whether tick-preventive measures were taken. When the villages were assessed for landscape risk factors, a particularly high seroprevalence for B vinsonii berkhoffii and A phagocytophilum was observed in a village at a relatively high altitude and greater distance from the Pacific coast, and montane hardwood conifer woodland was most associated with a high seroprevalence for these two pathogens.  相似文献   

17.
Our objectives were to estimate genetic parameters for carcass traits and evaluate the influence of slaughter end point on estimated breeding values (BV). Data provided by the American Simmental Association were divided into three sets: 1) 9,604 records of hot carcass weight (CW) and percentage retail cuts (PRC), 2) 6,429 records of CW, PRC, and marbling score (MS), and 3) 1,780 records of CW, PRC, MS, fat thickness (FT), and longissimus muscle area (LMA). Weaning weights (WW) from animals with carcass data and from their weaning contemporaries were used. Data were analyzed with a multiple-trait animal model and REML procedures to estimate genetic parameters and BV on an age-, CW-, MS-, or FT-constant basis. The model for carcass traits included fixed contemporary group and covariates for breed, heterozygosity, and slaughter end point and random additive direct genetic and residual effects. Weaning weight was preadjusted for founder effects, direct and maternal heterosis, age of dam, and age of calf. The model for WW included fixed contemporary group and random additive direct genetic, maternal genetic, maternal permanent environment, and residual effects. Heritabilities from data set 1 were 0.34 for CW and 0.25 for PRC on an age-constant basis and 0.25 for PRC on a CW end point. Heritabilities for data set 2 were 0.35, 0.24, and 0.36 for CW, PRC, and MS, respectively, on an age-constant basis. Data set 2 heritabilities were 0.25 for PRC and 0.34 for MS on a CW-constant basis and 0.33 for CW and 0.25 for PRC at a constant MS end point. Heritabilities on an age-constant basis for data set 3 were as follows: CW, 0.32; PRC, 0.09; MS, 0.12; FT, 0.10; and LMA, 0.26. Heritability estimates for data set 3 on a CW-, MS-, and FT-constant basis were similar to those on an age-constant basis. Heritabilities were 0.12 for PRC, 0.12 for MS, 0.14 for FT, and 0.22 for LMA on a CW-constant basis; 0.30 for CW, 0.09 for PRC, 0.10 for FT, and 0.28 for LMA at a constant MS end point; and 0.33, 0.17, 0.13, and 0.29 for CW, PRC, MS, LMA on a FT-constant basis. Genetic correlations among traits varied across groups and end points but suggested that it should be possible to select for improved lean yield without sacrificing quality grade. Correlations were calculated among BV computed at different end points. Adjustment to various end points resulted in some changes in BV and reranking of sires, especially for PRC; however, the number of records available had a larger influence than slaughter end point.  相似文献   

18.
畜牧业是张掖市的支柱产业,面对当前动物疫病防控形势依然严峻的现状,创建无疫小区是保障畜牧业持续稳定发展的必由之路,我市的规模养殖比重达较大,创建无疫小区的基础好,通过认真分析我市养殖现状和动物疫病防控形势后,针对创建养殖场无疫小区提出了出台扶持政策、加强宣传引导和落实管控措施的思路与对策,为我市创建无疫小区和无疫区,更好地做好动物疫病防控工作,保持畜牧业增收势头更强劲提出可供参考的建议。  相似文献   

19.
Several methods were evaluated for collecting fecal and intestinal samples from wild birds found near broiler chicken houses. A few intestinal samples and cloacal swabs were obtained from European starlings and house sparrows. Most of the samples collected consisted of wild bird droppings found on or near the houses. Samples were collected from each of four farms of a broiler integrator during a grow-out cycle: a cycle in the summer for farm A, fall for farm B, and spring, summer, fall, and winter for farms C and D. Of the 25 wild bird intestinal and fecal samples collected from a broiler house on farm A during a grow-out cycle in July-August 1997, 24% were positive for Salmonella spp., 4% for Campylobacter jejuni, and 28% for Clostridium perfringens. Of the nine fecal samples collected from broiler house B in a grow-out cycle in September-November 1997, 33% were positive for Salmonella spp., 11% for C. jejuni, and 22% for C. perfringens. For farms C and D, of the 23 samples collected in March-April 1998, 0 were positive for Salmonella spp., 11% for C. jejuni, and 52% for C. perfringens; of 27 samples collected in June-July 1998, 4% were positive for Salmonella spp., 0 for C. jejuni, and 13% for C. perfringens; of 24 samples collected in August-October 1998, 14% were positive for Salmonella spp., 5% for C. jejuni, and 4% for C. perfringens; of 14 samples collected December 1998-January 1999, 0 were positive for Salmonella, 50% for C. jejuni, and 14% for C. perfringens. The incidence of these bacterial enteropathogens in wild birds near the broiler chicken houses suggests that wild birds that gain entry to poultry grow-out houses have the potential to transmit these pathogens to poultry.  相似文献   

20.
Estimates of additive direct heritability (h2a) for traits such as litter size may be biased by maternal effects. The size of these effects was estimated using a derivative-free restricted maximum likelihood procedure under an animal model. First-parity records from Yorkshire (Y) and Landrace (L) gilts were obtained from the Quebec Record of Performance sow productivity program for 21,127 litters born between 1977 and 1987. Direct (sigma 2a) and maternal (sigma 2m) additive genetic variances, their covariance (sigma am) and error variance (sigma 2e) were estimated for total numbers born (NOBN), born alive (NOBA) and weaned (NOWN). Analysis of purebred Y and crossbred litters indicated that estimates of sigma 2a were of similar magnitude for all traits, with h2a ranging from .06 to .13. Except for L litters, estimates of sigma 2m were relatively low for NOBN and NOBA, and increased in size for NOWN, with h2m ranging from 0 to .08. Also, estimates of sigma am were negative, except for NOBN and NOBA with crossbred litters, and became increasingly negative for NOWN. Results from purebred L litters indicated there was a stronger negative correlation between direct and maternal genetic effects for NOBN and NOBA than for NOWN.  相似文献   

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