Detection of monensin residues in poultry liver using an enzyme immunoassay

Monensin, a carboxylic acid ionophore, is commonly fed to poultry to control coccidiosis. A method for the detection and quantification of monensin residues in liver has been developed, Samples (3 g) were extracted with acetonitrile-water and applied to a competitive enzyme immunoassay using a polyclonal antiserum raised against a monensin-transferrin conjugate, The limit of detection (mean + 3s) calculated from the analysis of 12 known negative samples was 2.91 ng g(-1). Intra- and inter-assay RSD were determined as 8.5 and 10.6%, respectively, using a liver sample fortified with 20 ng g(-1) monensin, A pharmacokinetic study in which 70 six week old broilers were fed monensin at a rate of 120 mg kg(-1) in their feed for 14 d resulted in mean monensin liver residues of 102 ng g(-1). However these had fallen below the limit of detection of the assay within the 3 d withdrawal period recommended by the manufacturer.

Development of a dual label time-resolved fluoroimmunoassay for the detection of beta-agonists in cattle urine

beta-Agonists are among the most widely abused drugs in veterinary medicine for the illegal promotion of farm animal growth. An array of analytical procedures has been developed to detect the residues of these compounds in many biological materials. As the number of beta-agonist formulations increases, it has become increasingly difficult to devise screening techniques capable of detecting a broad spectrum of these residues in a single test. A dual immunoassay based on time-resolved fluorescence was developed that incorporated a monoclonal antibody raised to tertiary butyl amines and a polyclonal antibody to biphenolic beta-agonists. This assay was capable of detecting residues of a range of beta-agonists present in bovine urine without the need for sample extraction. The limits of detection of the assay ranged from 1 to 8.5 ng ml(-1) depending on the cross-reactivity of individual compounds with the antibodies employed in the procedure.

Detection of ivermectin residues in bovine liver using an enzyme immunoassay

Ivermectin, a member of the avermectin group, is frequently used to control parasites in many food producing animal species. A method for the detection and quantification of ivermectin residues in bovine liver has been developed. Liver samples (4 g) were extracted with acetonitrile and applied to a competitive enzyme immunoassay using a polyclonal antiserum raised in rabbits against an ivermectin-transferrin conjugate, The limit of detection of the assay (mean +/- 3s) calculated from the analysis of 24 known negative samples was 1.6 ng g(-1), Intra- and inter-assay RSDs were determined as 8.8 and 14.6%, respectively, using a negative bovine liver sample fortified with 100 ng g(-1) of ivermectin. Four Friesian steers were treated with a pour-on application of ivermectin at a dose rate of 0.5 mg kg(-1) body mass then withdrawn and killed at 7, 14, 21 and 28 d, Livers mere removed and ivermectin residue concentrations determined using the proposed immunoassay procedure, Seven days post-treatment the ivermectin liver concentration was determined as 52.7 ng g(-1), decreasing to 4.1 ng(-1) at 28 d, All immunoassay results were confirmed using high-performance liquid chromatography (HPLC), The immunoassay and HPLC results for invermectin ranged from 1 to 58 ng g(-1) and were in close correlation (r = 0.99).

A simple competitive enzyme immunoassay for the detection of the trypanocidal drug isometamidium

A new competitive enzyme immunoassay technique has been developed for the determination of concentrations of the trypanocidal drug isometamidium chloride (Samorin) in bovine serum. The method has been shown to be highly repeatable and reproducible, and it has several advantages over previous immunoassay techniques for the drug. There are fewer incubation steps overall; microtitre plates may be of coated in batches and stored frozen for future use; and the competition incubation is overnight and is followed only by a brief colour development stage of 10 min. Coefficients of variation (CVs) of duplicate samples were similar to 5%, and mean response variances of untreated cattle (n = 57) were small (CV, 10%). Partitioning of variance showed 77% of this variability to be intrinsic to the samples, and the remaining 23% was due to the procedure. The limit of detection was approximately 0.5 ng ml(-1), which was considered to be satisfactory for the intended use of the method. The drug could be detected in serum of treated cattle for up to 10 weeks following treatment, and determinations showed a high level of reproducibility.

DETECTION OF CLENBUTEROL RESIDUES IN BOVINE LIVER, MUSCLE, RETINA AND URINE USING GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A gas chromatographic/mass spectrometric method is described for the detection of clenbuterol residues in liver, muscle, urine and retina. Tissue samples are first digested using protease and any clenbuterol present is extracted using a simple liquid/liquid extraction procedure. The dried extracts are then derivatized using methylboronic acid and the derivatives are subjected to gas chromatography/mass spectrometry on a magnetic sector instrument. The detection limit of the assay is 0.05 ng g-1 clenbuterol in liver, muscle or urine using a 10 g sample size, and 4 ng g-1 in retina using a 0.5 g sample size. The assay is made very specific by using selected ion monitoring of three ions at a resolution of 3500 and by ion ratio measurements. The precision and reproducibility of the assay are enhanced by the use of a deuterated internal standard, with a typical coefficient of variation of 3%.

Development and clinical validation of a loop-mediated isothermal amplification method for the rapid detection of Neisseria meningitidis

Loop-mediated isothermal amplification (LAMP) is an innovative technique that allows the rapid detection of target nucleic acid sequences under isothermal conditions without the need for complex instrumentation. The development, optimization, and clinical validation of a LAMP assay targeting the ctrA gene for the rapid detection of capsular Neisseria meningitidis were described. Highly specific detection of capsular N. meningitidis type strains and clinical isolates was demonstrated, with no cross-reactivity with other Neisseria spp. or with a comprehensive panel of other common human pathogens. The lower limit of detection was 6 ctrA gene copies detectable in 48 min, with positive reactions readily identifiable visually via a simple color change. Higher copy numbers could be detected in as little as 16 min. When applied to a total of 394 clinical specimens, the LAMP assay in comparison to a conventional TaqMan® based real-time polymerase chain reaction system demonstrated a sensitivity of 100% and a specificity of 98.9% with a ? coefficient of 0.942. The LAMP method represents a rapid, sensitive, and highly specific technique for the detection of N. meningitidis and has the potential to be used as a point-of-care molecular test and in resource-poor settings.

VLT DETECTION OF A RED SUPERGIANT PROGENITOR OF THE TYPE II-P SUPERNOVA 2008bk

We report the identification of a source coincident with the position of the nearby Type II-P supernova (SN) 2008bk in high-quality optical and near-infrared preexplosion images from the ESO Very Large Telescope (VLT). The SN position in the optical and near-infrared preexplosion images is identified to within about +/- 70 and +/- 40 mas, respectively, using postexplosion-band images obtained with the NAOS CONICA adaptive optics system K-s on the VLT. The preexplosion source detected in four different bands is precisely coincident with SN 2008bk and is consistent with being dominated by a single point source. We determine the nature of the point source using the STARS stellar evolutionary models and find that its colors and luminosity are consistent with the source being a red supergiant progenitor of SN 2008bk with an initial mass of 8.5 +/- 1.0 M-circle dot.

The WR content of IC10 - first detection of WC9 stars in a low metallicity environment?

We present deep, narrow-hand photometry of the Local Group starburst galaxy IC10. Our dedicated photometric system provides detection of 13 new Wolf-Rayet (WR) stars and allows spectral subtypes to be assigned. Three of these new stars appear to be WC9 subtypes. If confirmed, these would be the very first WC9 stars ever detected in a low metallicity environment, hence putting strong new constraints on the formation and evolution models of massive stars. Eight of the new WR stars are of the WC subtype, which does not significantly modify the anomalously high WC/WN ratio in IC10. However it is likely that a number of Wolf-Rayet stars of the WNE and WC spectral subtypes are still to be discovered in the heart of the galaxy.

Detection of short lived radioisotopes as a fast diagnostic for intense laser-solid interactions

As a diagnostic of high-intensity laser interactions (> 10(19) W cm(-2)), the detection of radioactive isotopes is regularly used for the characterization of proton, neutron, ion, and photon beams. This involves sample removal from the interaction chamber and time consuming post shot analysis using NaI coincidence counting or Ge detectors. This letter describes the use of in situ detectors to measure laser-driven (p,n) reactions in Al-27 as an almost real-time diagnostic for proton acceleration. The produced Si-27 isotope decays with a 4.16 s half-life by the predominantly beta+ emission, producing a strong 511 keV annihilation peak. (c) 2006 American Institute of Physics.

Immunological detection of Bacteroides fragilis in clinical-samples

A monospecific polyclonal antiserum, prepared against Bacteroides fragilis common polysaccharide antigen purified by polyacrylamide gel immunoblot detected B. fragilis, B. thetaiotaomicron, B. ovatus and Prevotella melaninogenica in pus samples from various anatomical sites by immunofluorescence microscopy of the pus. With standard clinical laboratory culture methods, 36% of 147 samples were positive for one or more of the above bacteria. Of these, B. fragilis accounted for 33%. By immunofluorescent labelling of pus with the common antigen antiserum the detection of these bacteria in the samples increased to 50%. All nine of the blood cultures in which B. fragilis was detected by culture contained bacteria positive for the common antigen. Immunofluorescent labelling of pus samples with a selection of monoclonal antibodies specific for surface polysaccharides which are known to be antigenically variable in culture in vitro and in an animal model of infection showed that these polysaccharides are also variable in natural infection. The results indicate that the common polysaccharide antigen, in contrast to the variable surface polysaccharides, is a suitable target for the immunodetection of B, fragilis in clinical samples from a range of anatomical sites.

A study of endonuclease III-sensitive sites in irradiated DNA: detection of alpha-particle-induced oxidative damage

An important difference between chemical agents that induce oxidative damage in DNA and ionizing radiation is that radiation-induced damage is clustered locally on the DNA, Both modelling and experimental studies have predicted the importance of clustering of lesions induced by ionizing radiation and its dependence on radiation quality. With increasing linear energy transfer, it is predicted that complex lesions will be formed within 1-20 bp regions of the DNA, As well as strand breaks, these sites may contain multiple damaged bases, We have compared the yields of single strand breaks (ssb) and double strand breaks (dsb) along with those produced by treatment of irradiated DNA with the enzyme endonuclease III, which recognizes a number of oxidized pyrimidines in DNA and converts them to strand breaks. Plasmid DNA was irradiated under two different scavenging conditions to test the involvement of OH radicals with either Co-60 gamma-rays or alpha-particles from a Pu-238 source. Under low scavenging conditions (10 mM Tris) gamma-irradiation induced 7.1x10(-7) ssb Gy/bp, which increased 3.7-fold to 2.6 x 10(-6) ssb Gy/bp with endo III treatment. In contrast the yields of dsb increased by 4.2-fold from 1.5 x 10(-8) to 6.3 x 10(-8) dsb Gy/bp, This equates to an additional 2.5% of the endo III-sensitive sites being converted to dsb on enzyme treatment. For alpha-particles this increased to 9%. Given that endo III sensitive sites may only constitute similar to 40% of the base lesions induced in DNA, this suggests that up to 6% of the ssb measured in X- and 22% in alpha-particle-irradiated DNA could have damaged bases associated with them contributing to lesion complexity.