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V Spiehler

Publications and source records attributed to V Spiehler.

25 records · Page 2Linked to original sources
PubMedDate not supplied

Application of expert systems analysis to interpretation of fatal cases involving amitriptyline.

Part I. Expert 4: The object of this study was to investigate the applicability of commercially available expert system shells to interpretation in forensic toxicology. Amitriptyline toxicology was selected as a pilot trial. Blood and tissue concentrations of amitriptyline and nortriptyline in fatal and nonfatal amitriptyline cases from the literature and from the Registry of Human Toxicology databank were entered into the expert system shell Expert 4 (Rivers, Elsevier). The statistical evaluation routines of the shell were used to search for patterns in the data. Successive changes in the data base were made to test for the influence of the data base on the conclusions. Finally the data base was refined, based on the evaluations, to strengthen the probabilities of the conclusions. The refined database was coupled with the Expert 4 inference engine to infer unknown parameters in the cases. The results of the expert system analysis were compared to known values and published expert opinions. The ratio of amitriptyline/nortriptyline and tissue levels of nortriptyline were found to be the most significant measures for interpretation of effect and time since ingestion. Part II. Computer Induction of Rules: Blood and tissue concentrations of amitriptyline and nortriptyline in fatal and nonfatal amitriptyline cases from the literature and from the Registry of Human Toxicology databank were entered into the expert system shell BEAGLE, (Forsyth, Machine Learning Research, Ltd.). The automatic rule induction routines of the shell were used to search for patterns in the data. The program expressed these patterns as numerical predictions or Boolean logic rules. The results were compared to those obtained with the Expert 4 (Rivers, Elsevier) using the same case knowledge base.(ABSTRACT TRUNCATED AT 250 WORDS)

Amitriptyline↗
PubMedDate not supplied

Methamphetamine in antemortem blood and urine by radioimmunoassay and GC/MS.

Methamphetamine abuse is increasing and methamphetamine is second only to alcohol as a positive finding in cases submitted to the San Diego Sheriff's Crime Laboratory. In general, whole blood specimens are submitted more often than urine. A modified version of a commercially available radioimmunoassay, Coat-A-Count (CAC) Methamphetamine, was investigated as a screen for methamphetamine in whole blood and urine. The assay was modified by using 100 microL of sample, making up standards in whole beef blood, extending the incubation time to 2 h or overnight, and using a cutoff reference of 50 ng/mL methamphetamine. The detection limit for the CAC Methamphetamine kit was 20 ng/mL methamphetamine in whole blood. The CAC Methamphetamine results were compared to Abuscreen Amphetamine High Specificity results and to gas chromatography/mass spectrometry (GC/MS) quantitation of amphetamine and methamphetamine for 157 positive and 48 negative blood specimens. With the CAC Methamphetamine assay there were 2 false negatives detected, both less than the 50 ng/mL cutoff level. There were 12 (6%) false positives with the CAC Methamphetamine assay and 29 (14%) false positives with the Abuscreen Amphetamine assay. Of the positive samples, 95% contained only methamphetamine, with an average concentration of 308 ng/mL, range 25-2030 ng/mL.

Evaluation Studies as Topic↗
PubMedDate not supplied

Whole blood quality assurance control samples for forensic toxicology.

Pilot studies were undertaken to examine the feasibility of preparing freeze-dried whole blood samples containing drugs of interest to be used as assay controls. The availability of such samples will enable analysts and laboratory managers to monitor analytical performance. A pilot batch of freeze-dried blood containing five compounds of forensic significance and a blank blood sample were prepared for reconstitution to 2.5-mL aliquots. Samples of each of these preparations were distributed to 55 laboratories in the USA and UK for analysis. A summary of the results is presented along with comments on the feasibility of producing freeze-dried whole blood samples for use in forensic toxicology.

Animals↗
PubMedDate not supplied

Whole blood deproteinization for drug screening using automatic pipettors.

Automating the initial screening of postmortem blood and other tissues for drugs of abuse requires a pipetting procedure that is compatible with immunoassay screening tests. The deproteinization procedure uses a zinc sulfate-5-sulfosalicylic acid reagent to precipitate blood proteins. This procedure for deproteinization of whole blood and tissue homogenates is compatible with coated tube radioimmunoassays (RIA) and can therefore be used in automating the initial screening step.

Automation↗