Ekins J.,U.S. Food and Drug Administration |
Peters S.M.,U.S. Food and Drug Administration |
Jones Y.L.,U.S. Food and Drug Administration |
Swaim H.,U.S. Food and Drug Administration |
And 8 more authors.
Journal of Food Protection | Year: 2012
The U.S. Food and Drug Administration (FDA) has previously validated a real-Time PCR-based assay that is currently being used by the FDA and several state laboratories as the official screening method. Due to several shortcomings to the assay, a multiplex real-Time PCR assay (MRTA) to detect three ruminant species (bovine, caprine, and ovine) was developed using a lyophilized bead design. The assay contained two primer or probe sets: A "ruminant" set to detect bovine-, caprine-, and ovinederived materials and a second set to serve as an internal PCR control, formatted using a lyophilized bead design. Performance of the assay was evaluated against stringent acceptance criteria developed by the FDA's Center for Veterinary Medicine's Office of Research. The MRTA for the detection of ruminant DNA passed the stringent acceptance criteria for specificity, sensitivity, and selectivity. The assay met sensitivity and reproducibility requirements by detecting 30 of 30 complete feed samples fortified with meals at 0.1% (wt/wt) rendered material from each of the three ruminant species. The MRTA demonstrated 100% selectivity (0.0% false positives) for negative controls throughout the assessment period. The assay showed ruggedness in both sample selection and reagent preparation. Second and third analyst trials confirmed the quality of the written standard operating procedure with consistency of results. An external laboratory participating in a peer-verification trial demonstrated 100% specificity in identifying bovine meat and bone meal, while exhibiting a 0.03% rate of false positives. The assay demonstrated equal levels of sensitivity and reproducibility compared with the FDA's current validated real-Time PCR assay. The assay detected three prohibited species in less than 1.5 h of total assay time, a significant improvement over the current real-Time assay. These results demonstrated this assay's suitability for routine regulatory use both as a primary screening tool and as a confirmatory test. © International Association for Food Protection.
Ou G.,301 Centennial Mall South |
Li R.,Southern Illinois University Carbondale |
Pun M.,301 Centennial Mall South |
Osborn C.,301 Centennial Mall South |
And 3 more authors.
Journal of Hydrology | Year: 2016
The conventional numerical method is computationally intensive and prone to numerical noises for stream depletion analyses using MODFLOW. In this study, a new MODFLOW package has been developed to improve the computational efficiency and reduce the noises for each simulation. Using the assumption of unchanged flow coefficients between the baseline and scenario runs, the nonlinear groundwater flow system is linearized for solving the flow equations. The new package has been successfully applied to a regional groundwater model in Nebraska. The results show that the numerical noises, commonly identified in conventional approach, have been significantly reduced and a twenty-fold speedup has been achieved for a regional groundwater model in Nebraska. The results suggest this package can be adapted to be a component of optimization tools for water management scenario analyses especially when a large number of scenario model runs are involved. © 2015 Elsevier B.V.