994 resultados para Toxicology.


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Furazolidone, a nitrofuran antibiotic, is banned from use in food animal production within the European Union. Increasingly, compliance with this ban is monitored by use of analytical methods to detect a stable tissue-bound metabolite, 3-amino-2-oxazolidinone (AOZ). Widespread use of furazolidone in poultry and prawns imported into Europe highlighted the urgent need for development of nitrofuran immunoassay screening tests. The first enzyme-linked immunoabsorbant assay for detection of AOZ residues in prawns (shrimps) is now described. Prawn samples were derivatized with o-nitrobenzaldehyde, extracted into ethyl acetate, washed with hexane and applied to a competitive enzyme immunoassay based on a rabbit polyclonal antiserum. Assay limit of detection (LOD) (mean+3 s) calculated from the analysis of 20 known negative cold and warm water prawn samples was 0.1 mug kg(-1). Intra- and interassay relative standard deviations were determined as 18.8 and 38.2%, respectively, using a negative prawn fortified at 0.7 mug kg(-1). The detection capability (CCbeta), defined as the concentration of AOZ at which 20 different fortified samples yielded results above the LOD, was achieved at fortification between 0.4 and 0.7 mug kg(-1). Incurred prawn samples (n=8) confirmed by liquid chromatography coupled with tandem mass spectrometry detection to contain AOZ concentrations between 0.4 and 12.7 mug kg(-1) were all screened positive by this enzyme-linked immunoabsorbant assay. Further data are presented and discussed with regard to calculating assay LOD based on accepting a 5% false-positive rate with representative negative prawn samples. Such an acceptance improves the sensitivity of an ELISA and in this case permitted an LOD of 0.05 mug kg(-1) and a CCbeta of below 0.4 mug kg(-1).

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Zeranol, an oestrogenic growth promoter in food animals, is banned within the European Union (EU). However, commercially available immunoassay kits for zeranol cross-react with toxins formed by naturally occurring Fusarium spp. fungi, leading to false-positive screening results. This paper describes the validation of a specificity enhanced, rapid dry reagent time-resolved fluoroimmunoassay (TR-FIA) for zeranol (recovery 99%, limit of detection 1.3 ng ml(-1)) demonstrating that up to 150 ng ml(-1) of Fusarium spp. toxins in urine do not lead to false-positive results. This assay will assist EU Member States to implement Council Directive 961 23\EC, which requires states to monitor for potential abuses of zeranol. A similar TR-FIA for the Fusarium spp. toxin a-zearalenol, using the same sample extract, is also described (recovery 68%, limit of detection 5.6 ng ml(-1)). Only the addition of diluted sample extract is required to perform these dry-reagent TR-FIAs, the results being available within 1 h of extract application. The EU-funded project 'Natural Zeranol' (FAIR5-CT97-3443) will use these fluoroimmunoassays to screen bovine urine in four Member States to gather data on the seasonality of Fusarium spp. toxin contamination of urine and the incidence of zeranol screening test positives.

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Regulatory authorities, the food industry and the consumer demand reliable determination of chemical contaminants present in foods. A relatively new analytical technique that addresses this need is an immunobiosensor based on surface plasmon resonance (SPR) measurements. Although a range of tests have been developed to measure residues in milk, meat, animal bile and honey, a considerable problem has been encountered with both serum and plasma samples. The high degree of non-specific binding of some sample components can lead to loss of assay robustness, increased rates of false positives and general loss of assay sensitivity. In this paper we describe a straightforward precipitation technique to remove interfering substances from serum samples to be analysed for veterinary anthelmintics by SPR. This technique enabled development of an assay to detect a wide range of benzimidazole residues in serum samples by immunobiosensor. The limit of quantification was below 5 ng/ml and coefficients of variation were about 2%.

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A rapid imununoassay using an optical biosensor (BIAcore(TM)) for determining the presence of sulphadiazine (SDZ) residues in pig bile was developed. SDZ,cas immobilised onto the surface of a dextran-coated silicon chip and a solution containing SDZ antibody, sample and buffer was injected over the chip surface. The level of antibody binding to the chip was determined after 20 s and the surface of the chip was then regenerated over a 1-min period prior to another sample injection taking place. Standard curves were constructed to allow quantification of SDZ presence in sample. Concentrations ranging from 0 to 10.64 mu g ml(-1) SDZ were detected in bile samples taken from experimentally fed pigs and randomly selected pigs taken from a local slaughterhouse. These results were compared to the concentrations of SDZ detected by high-performance liquid chromatography: in associated tissues. When concentrations in bile exceeded 0.6 mu g ml(-1) SDZ, the corresponding edible tissue was above the maximum residue level (MRL), i.e. 0.1 mu g g(-1) in 13 out of 14 cases. Wizen the bile concentration was less than 0.6 mu ml(-1) the associated tissue concentrations never exceeded rite MRL. This experiment has indicated that biosensor analysis of bile is a highly effective method for detecting violative SDZ residues in meat.

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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.

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1. Extracts of the liver fluke, Fasciola hepatica from three different hosts (cow, sheep, rat) have been subjected to radioimmunoassay using antisera to 6 mammalian regulatory peptides.

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Background: Studies of the adverse neurobehavioral effects of maternal alcohol consumption on the fetus have been largely confined to the postnatal period, after exposure to alcohol has finished. This study explored the brain function of the fetus, at the time of exposure to alcohol, to examine its effect on information processing and stability of performance. Methods: Five groups of fetuses, defined by maternal alcohol consumption patterns, were examined: control (no alcohol); moderate (5 to 10 units/wk either drunk evenly across the week or as a binge, in 2 to 3 days); heavy (20+ units/wk drunk evenly or as a binge). Fetal habituation performance was examined on 3 occasions, separated by 7 days, beginning at 35 weeks of gestation. The number of trials required to habituate on each test session and the difference in performance across test sessions were recorded. Results: Fetuses exposed to heavy binge drinking required significantly more trials to habituate and exhibited a greater variability in performance across all test sessions than the other groups. Maternal drinking, either heavily but evenly or moderately as a binge, resulted in poorer habituation, and moderate binge drinking resulted in greater variability compared with no, or even, drinking. Conclusions: Decreased information processing, reflected by poorer habituation, and increased variability in performance may reflect the initial manifestations of structural damage caused by alcohol to the brain. These results will lead to a greater understanding of the effects of alcohol on the fetus's brain, enable the antenatal identification of fetal alcohol spectrum disorders, and lead to the early implementation of better management strategies. © 2012 by the Research Society on Alcoholism.


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Reaxys Database Information|

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Objective To assess current experiences and attitudes of hospital based paediatricians towards off-label medicine prescribing. Setting Paediatric hospital wards and out-patient clinics. Design A prospective, questionnaire based study. Results A 30 item questionnaire was sent to 300 hospital based paediatricians and 250 (83%) were returned completed. Over 69% of responders were familiar with the term off-label medicines. However, only 28% were knowingly prescribing off-label medicines to children. The majority of respondents (90%) expressed concerns about the safety and efficacy of off-label medicines. Only 15% had observed Adverse Drug Reactions, and 31% a treatment failure. The vast majority of respondents (83%) did not obtain informed consent or tell parents they were prescribing off label medicines to their children. Conclusions Off-label prescribing of medicines to children is a familiar concept to the majority of paediatricians in Jordan although only a smaller number are aware that it is common in their practice. Respondents showed concern about off label prescribing, although the majority do not consider it necessary to inform parents. More comprehensive research is needed in this area in Jordan and other Middle Eastern countries.

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The implementation of a new model for drug selection in Northern Ireland has improved the quality of prescribing, safety and reduced costs.

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Objective: To assess the views of the Maltese general public on services provided by community pharmacies in Malta and their opinions on the proposed extended role for pharmacies.

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Objective: The buccal absorption of captopril does not exhibit the classical pH/partition hypothesis, suggesting that mechanisms other than passive diffusion are involved in its absorption; animal studies have suggested that a peptide carrier-mediated transport system may be responsible for its absorption. The present study evaluated the effects of pH on octanol partitioning, and on the buccal absorption of enalapril and lisinopril, using in vitro techniques and buccal partitioning in human volunteer subjects.

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We evaluated a structured pharmaceutical care program for elderly patients (> 65 yrs) with congestive heart failure (CHF) based on objective measures of disease control, quality of life, and use of health care facilities in a randomized, controlled, longitudinal, prospective clinical trial. The 42 patients in group A received education from a pharmacist on the disease and its treatment, and lifestyle changes that could help control symptoms. Patients also were encouraged to monitor their symptoms and comply with prescribed drug therapy. If necessary, dosage regimens were simplified in liaison with hospital physicians. The 41 control patients (group B) received standard care. The following outcome measures were assessed in all patients at baseline (before the start of the trial) and at 3, 6, 9, and 12 months: 2-minute walk test, blood pressure, body weight, pulse, forced vital capacity, quality of life [disease-specific (Minnesota Living with Heart Failure questionnaire) and generic (SF-36)], knowledge of symptoms and drugs, compliance with therapy, and use of health care facilities (hospital admissions, visits to emergency room, emergency calls). Patients in group A showed improved compliance with drug therapy, which in turn improved their exercise capacity compared with those in group B; education on management of symptoms, lifestyle changes, and dietary recommendations were also of benefit. Group A patients significantly improved knowledge of their drug therapy over the 12-month study and had fewer hospital admissions compared with group B patients. They also had improved outcomes compared with group B, despite the small samples. An extension of this trial to other sites with pooling of results would provide additional evidence of the value of this structured program in elderly patients with CHF.