A specificity-enhanced time-resolved fluoroimmunoassay for zeranol employing the dry reagent all-in-one-well principle

A simple dry chemistry time-resolved fluorescence immunoassay (TR-FIA) method was developed for the measurement of zeranol in bovine urine samples. The samples were purified by immunoaffinity chromatography and a specificity-enhanced zeranol antibody was employed in the immunoassay. This resulted in a highly selective method, which had only negligible reactivity with Fusarium spp, toxins. The all-in-one-well dry chemistry concept made the assay very simple to use because all the assay-specific reagents were already present in the reaction wells in dry form. Only the addition of diluted sample extract was required to perform the competitive one-step TR-FIA and the results were available in less than 1 h. The analytical limit of detection (mean + 3s) for the immunoassay was 0.16 ng ml(-1) (n=12) and the functional limit of detection for the whole method, estimated by the analysis of zeranol-free samples, was 1.3 ng ml(-1) (n=20). The recovery of zeranol at the level of 2 ng ml(-1) was 99% (n=18) and the within-assay variation ranged between 4.5 and 9.0%.

Comparison of the efficiences of enzymatic and chemical hydrolysis of (nortestosterone and diethylstilboestrol) glucuronides in bovine urine

Residues of 19-nortestosterone (19-NT) and diethylstilboestrol (DES) are excreted in bovine urine, mainly conjugated to glucuronic acid. Prior to quantification, urine must be deconjugated, which is commonly performed by enzymatic or chemical hydrolysis. The efficiencies of two enzymatic and two chemical deconjugation methods were studied. The range of efficiencies obtained for DES were 51.8% (beta -glucuronidase, incubation at 37 degreesC overnight) and 2.7% (methanolic HCl), respectively. Similarly, efficiencies for NT ranged from 43.1% (beta -glucuronidase, incubation at 55 degreesC for 2 h) to 12.7% (methanolic HCl). The results highlight that within control laboratories significant underestimation of drug residue content in samples may occur, due to poor deconjugation. (C) 2001 Elsevier Science B.V. All rights reserved.

Comparison of two polyclonal antibodies for the detection of 19-nortestosterone in bovine bile by ELISA

19-Nortestosterone (beta-NT) is banned for use as a growth promoter in food animals within the European Union. For regulatory control purposes, urine and bile samples are routinely screened by immunoassay. The aim of the present study was to compare the ability of two immunoassays, using two rabbit polyclonal antibodies raised against two different NT derivatives, to detect NT residues in bovine bile. One antiserum cross-reacted with both alpha-NT and beta-NT (alpha/beta-NT), whereas the other was specific for alpha-NT. Bile samples from 266 slaughtered cattle were deconjugated and analyzed using both antibodies, with all screening positives (>2 ng ml(-1)) confirmed by high resolution gas chromatography mass spectrometry. The alpha/beta-NT and alpha-NT antibody-based ELISAs screened 39 and 44 samples positive, respectively, with NT confirmed in 22 and 39, respectively. The alpha/beta-NT antibody-based ELISA produced a false-negative rate of 44% compared to 0% for the alpha-NT antibody-based ELISA. Supplementary investigations concluded that a matrix effect was a major cause of the marked differences in false-negative rates. This result underlines the necessity to validate immunoassays in the sample matrix.

Increased diagnosis and detection rates of carcinoma in situ of the breast

The purpose of this study was to identify trends in the diagnosis of carcinoma in situ (CIS) of the breast in the United Kingdom (UK) and the Republic of Ireland (ROI) and to examine the impact of mammography. Data on cases of newly diagnosed CIS of the breast and mode of detection (screen detected or not) were obtained, where available, from regional cancer registries between 1990 and 2007. Age-standardised diagnosis rates for the UK and the ROI, and regional screen detected diagnosis rates were compared by calculating the annual percentage change (APC) over time. The APC of the diagnosis rate amongst women aged 50-64 years (original screening age group) showed a significant 5.9% increase in the UK (1990-2007) and 11.5% increase in the ROI (1994-2007). The rate of diagnosis (50-64 years) stabilized in the UK between 2005 and 2007 and was substantially higher than in other western populations with national screening programmes. The APC of the diagnosis rate amongst those aged 65-69 years showed a significant 12.4% increase in the UK (1990-2007) and 10.3% increase in the ROI (1994-2007). amongst women aged 50-74 years in the UK, approximately 4,300 cases of CIS (˜90% ductal carcinoma in situ) were diagnosed in 2007. Our analyses have shown that screen detected CIS contributed primarily to the increase in diagnosis of CIS of the breast. The high diagnosis rate of screen detected CIS of the breast underlines the need for further research into lesion and patient characteristics that are related to progression of CIS to invasive disease to better target treatment. © 2012 Springer Science+Business Media, LLC.

The level playing field: the impact of assessment practice on professional development

Context: The effects of assessment practice on students’ learning are unclear, particularly regarding professional development. Corralling in objective structured clinical examinations (OSCEs) is designed to reduce illicit passing of examination information. Candidates completing an examination are kept secluded until the next cohort of examinees has begun. We used the introduction of corralling as a context in which to explore social influences on examination misconduct, with the aims of improving understanding of the hidden effects of assessment, and evaluating the acceptability of corralling from the student perspective.

Methods: A questionnaire was administered to students corralled post-OSCE for the first time. Eleven semi-structured interviews were subsequently conducted. Questionnaire data were analysed for descriptive statistics and thematic analysis of interview transcripts was carried out.

Results: The questionnaire response rate was 95.4% (251/263). Before corralling, 80.9% (203/251) of students were aware of the sharing of information among peers and 78.5% (197/251) agreed that such misconduct was unprofessional. The majority were in favour of corralling (90.8%, 228/251). Four themes emerged from the semi-structured interviews: the student network versus the individual; assessment-driven culture; the deferring of professionalism, and the ‘level playing field’. Students saw interaction within the student network, on a background of assessment-driven culture, as the key driver in examination misconduct. Conforming to the rules of the social network was prioritised over individual agency, although the mismatch between the rules of the network and the dominant professional discourse caused some conflict for individuals. Deferred professionalism (described as the practice of taking on the norms of professional behaviour only when qualified) was a rationalisation used to minimise this conflict. Corralling provided a ‘level playing field’ in which the influences of the network were minimised.

Conclusions: Examination misconduct is thus a complex social construction with implications for individual learners in terms of professional development. Corralling is one mechanism for addressing misconduct that is acceptable to students, but assessment processes have important hidden effects which educators should acknowledge.

Reliability Assessment of 3-D Space Frame Structures Applying Stochastic Finite Element Analysis

Throughout design development of satellite structure, stress engineer is usually challenged with randomness in applied loads and material properties. To overcome such problem, a risk-based design is applied which estimates satellite structure probability of failure under static and thermal loads. Determining probability of failure can help to update initially applied factors of safety that were used during structure preliminary design phase. These factors of safety are related to the satellite mission objective. Sensitivity-based analysis is to be implemented in the context of finite element analysis (probabilistic finite element method or stochastic finite element method (SFEM)) to determine the probability of failure for satellite structure or one of its components.

Numerical and Experimental Investigation of Aircraft Panel Deformations During Riveting Process

In collaboration with Airbus-UK, the dimensional growth of aircraft panels while being riveted with stiffeners is investigated. Small panels are used in this investigation. The stiffeners have been fastened to the panels with rivets and it has been observed that during this operation the panels expand in the longitudinal and transverse directions. It has been observed that the growth is variable and the challenge is to control the riveting process to minimize this variability. In this investigation, the assembly of the small panels and longitudinal stiffeners has been simulated using static stress and nonlinear explicit finite element models. The models have been validated against a limited set of experimental measurements; it was found that more accurate predictions of the riveting process are achieved using explicit finite element models. Yet, the static stress finite element model is more time efficient, and more practical to simulate hundreds of rivets and the stochastic nature of the process. Furthermore, through a series of numerical simulations and probabilistic analyses, the manufacturing process control parameters that influence panel growth have been identified. Alternative fastening approaches were examined and it was found that dimensional growth can be controlled by changing the design of the dies used for forming the rivets.

Virtual Engineering Centre - Examples of Virtual Prototyping and Multidisciplinary Design Optimization

The requirement for the use of Virtual Engineering, encompassing the construction of Virtual Prototypes using Multidisciplinary Design Optimisation, for the development of future aerospace platforms and systems is discussed. Some of the activities at the Virtual Engineering Centre, a University of Liverpool initiative, are described and a number of case studies involving a range of applications of Virtual Engineering illustrated.

Common variants at the MHC locus and at chromosome 16q24.1 predispose to Barrett's esophagus

Barrett's esophagus is an increasingly common disease that is strongly associated with reflux of stomach acid and usually a hiatus hernia, and it strongly predisposes to esophageal adenocarcinoma (EAC), a tumor with a very poor prognosis. We report the first genome-wide association study on Barrett's esophagus, comprising 1,852 UK cases and 5,172 UK controls in the discovery stage and 5,986 cases and 12,825 controls in the replication stage. Variants at two loci were associated with disease risk: chromosome 6p21, rs9257809 (P(combined) = 4.09 × 10(-9); odds ratio (OR) = 1.21, 95% confidence interval (CI) =1.13-1.28), within the major histocompatibility complex locus, and chromosome 16q24, rs9936833 (P(combined) = 2.74 × 10(-10); OR = 1.14, 95% CI = 1.10-1.19), for which the closest protein-coding gene is FOXF1, which is implicated in esophageal development and structure. We found evidence that many common variants of small effect contribute to genetic susceptibility to Barrett's esophagus and that SNP alleles predisposing to obesity also increase risk for Barrett's esophagus.

Mass spectrometric analysis of muscle samples to detect potential antibiotic growth promoter misuse in broiler chickens

Mass spectrometric methods were developed and validated for the analysis in chicken muscle of a range of antibiotic growth promoters: spiramycin, tylosin, virginiamycin and bacitracin, and separately for two marker metabolites of carbadox (quinoxaline-2-carboxylic acid and 1,4-bisdesoxycarbadox), and a marker metabolite of olaquindox (3-methyl-quinoxaline-2-carboxylic acid). The use of these compounds as antibiotic growth promoters has been banned by the European Commission. This study aimed to develop methods to detect their residues in muscle samples as a means of checking for the use of these drugs during the rearing of broiler chickens. When fed growth-promoting doses for 6 days, spiramycin (31.4 mu g kg(-1)), tylosin (1.0 mu g kg(-1)), QCA (6.5 mu g kg(-1)), DCBX (71.2 mu g kg(-1)) and MQCA (0.2 mu g kg(-1)) could be detected in the muscle 0 days after the withdrawal of fortified feed. Only spiramycin could consistently be detected beyond a withdrawal period of 1 day. All analytes showed stability commercial cooking process, therefore raw or cooked muscle could be used for monitoring purposes.

Nitrofuran antibiotic residues in pork The FoodBRAND retail survey

Use of nitrofuran drugs in food-producing animals has been prohibited within the EU because they may represent a public health risk. Monitoring compliance with the ban has focused on the detection of protein-bound nitrofuran metabolites which, in contrast to the parent compounds, are stable and persist in animal tissues. As part of the "FoodBRAND" project, an extensive survey of pork was undertaken across 15 European countries. Samples (n = 1500) purchased at retail outlets were analysed for the nitrofuran metabolites AOZ, AMOZ, AHD and SEM using LC-MS/MS determination of nitrobenzaldehyde derivatives. Limits of quantification for the method were 0.1 mug/kg (AOZ, AMOZ), 0.2 mug/kg (SEM) and 0.5 mug/kg (AHD). Of the 1500 samples tested, measurable residues of nitrofuran metabolites were confirmed in 12 samples (0.8% incidence overall) of which 10 samples were purchased in Portugal (AOZ, 0.3 mug/kg; AMOZ, 0.2-0.6 mug/kg) and one sample each in Italy (AMOZ, 1.0 mug/kg) and Greece (AOZ, 3.0 mug/kg). (C) 2004 Elsevier B.V. All rights reserved.