Assessment of a video system for scanning DNA autoradiographs

A video based scanning system had been developed for processing DNA autoradiographs (T. Catterick and J.R. Russell, Lab. Microcomput. (1991), in press). Before the scanner was used in casework it was necessary to assess its performance. Test DNA samples containing fragments (alleles) of known kilobase size were run against the primary (Amersham, U.K.) calibration ladder. The resulting autoradiographs were processed with the new video scanner and also using manual, ruler based measurements. Comparisons were then made between these experimental results and also with the known kilobase values quoted by the supplier of the test samples.     

Determining priorities and investment levels in scientific research and development

The differing viewpoints on resource allocation in research and development are reviewed and the criteria for rational planning discussed. The significance of different sets of criteria and their practicability are explored and it is concluded that the application of cost-benefit analysis methods, while imperfect, is the best basis for rational decisionmaking in the present state of knowledge. Society has as yet no clearly defined goals and this poses problems for the analyst particularly since social attitudes appear to be undergoing a particularly rapid change at the present time.     

Screening postmortem whole blood for oxycodone by ELISA response ratios

The objective of this study was to investigate the accuracy of screening postmortem whole blood for oxycodone using the ratio of the oxycodone immunoassay response to the response for the specimen obtained with a general opiate-class immunoassay. Fifty eight specimens which were negative for opiates and 158 postmortem whole blood specimens positive for opiates including 66 specimens known to contain oxycodone were assayed. Specimens were diluted 1:5 with assay buffer and analyzed by both the Neogen Oxymorphone/Oxycodone ELISA and the Neogen Opiate Group ELISA (Neogen Corporation, Lexington KY). The oxycodone equivalents in ng/mL from the Oxymorphone/Oxycodone ELISA were divided by the morphine equivalents in ng/mL from the Opiates ELISA to obtain an Oxycodone/Opiates Response Ratio. This ratio was compared with the GC/MS data for all specimens and for opiate positive specimens. Receiver Operating Characteristic (ROC) analysis suggested that optimum relative response ratio was 2.0. The sensitivity of the ELISA response ratio for the presence of oxycodone at a response ratio cutoff of 2.0 was 89.4% +/- 3.8% and the specificity was 88.1% +/- 3.2%. Specimens with a ratio of 2.0 or higher had a greater than 50% probability (positive predictive value) of containing oxycodone in a population with a greater than 15% prevalence of oxycodone.