Browsing by Subject "forensic samples"
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Item Evaluation of Applied Biosystems' Real-Time Human Quantification Assays(2003-05-01) Hybki, Dixie Lee Peters; John Planz; Arthur Eisenberg; Joseph WarrenTo aid the forensic community with its quantification issues, Applied Biosystems is currently developing human specific and human male specific quantification assays using Real-Time PCR (RT-PCR) and TaqMan probes. The human specific assay amplifies an autosomal specific gene, located on chromosome five, while the human male specific assay amplifies a region on the Y chromosome. The purpose of this project was to evaluate the assays with forensic samples to determine if the use of these kits would be appropriate to the forensic community. These kits are not commercially available at the time of this writing. Therefore, several details have been omitted to protect the patent and legal issues that are still pending. It is expected that these assays will surpass the sensitivity and specificity of current methods. This will not only meet, but also exceed the standard set forth by the DAB. By providing additional information such as human male DNA quantification and PCR inhibitor detection, these kits can provide what the forensic community has been lacking. The human male DNA detection and quantification is valuable in providing proof that male DNA was present in an intimate sample from a sexual assault case. This would be especially important in a case in which the offender was a vasectomized male, and for resolving mixtures of the victim and offender’s genetic profiles. The detection of PCR inhibitors for the elimination of futile genetic analysis is a novel component that would provide additional advantages. These kits will offer means for proper quantification to allow for minimal space waste, and allow for successful multiplex PCR within its optimal range. Today, STR analysis will proceed, and is often successful, even if no quantification results are obtained with current methods. The legal system questions this approach. The ability of autosomal specific and Y-chromosome specific RT-PCR quantification assays to assess low level DNA would provide the justification for subsequent analysis that would quiet the legal system’s arguments concerning human quantification.Item Evaluation of the SlicPrep 96 Device for Use in Extraction of Forensic Samples on the Biomek 2000 Laboratory Automation Workstation(2005-07-01) Plopper, Farah Jo Homsi; Joseph Warren; Arthur Eisenberg; John PlanzThe purpose of this study was to evaluate the Slicprep ™ 96 Device for extraction of forensic samples on the BioMek® 2000 robot to determine if it can further automate and increase the efficiency of the extraction process as well as generate optimal DNA yields with no contamination. This validation study was not as comprehensive as PBSO's validation of the BioMek® 2000, because the platform and reagents used were the same. The differences include the use of the Slicprep™ 96 Device during extraction and the slight modifications to protocol that were made to accommodate this device.Item Evaluation of Unlabeled Primers for Sex Determination of Animal and Wildlife Samples(2006-07-01) Price, Glynis Nicola; John Planz; Arthur Eisenberg; Joseph WarrenSpecies identification is not only important in determining the origins of remains found in human forensic cases, but is also important in the growing field of nonhuman forensics. Animal forensics is an emerging discipline in the non-human forensics field. Animal forensics focuses on domestic animals, or animals that live in close contact with humans. These animals include dogs, cats, cattle, pigs, horses, sheep as well as others. Objective 1: Sensitivity - Forensic samples are often low copy number so there may be little viable or non-degraded DNA to work with. The PCR reaction needs to be optimized to determine how little DNA you can start with and still obtain accurate results. The given protocol from DNA Solutions, Inc. (Appendix A) [ 17] suggests 20ng of input DNA. In practice, this level is rarely found in forensic cases, so this assay will begin at 5ng of 9 input DNA. The dilution series will be 5ng, 2ng, 1 ng, 500pg, 250pg, 125pg, 62.5pg, 31.25pg and 15.63pg. Objective 2:PCR cycle number- As a part of sensitivity, PCR cycle number is an important part of optimizing the reaction. Since agarose gels are being run to visualize results, increased cycle number can result in increased specificity. Cycle numbers being evaluated are 26 cycles [ 17], 28 cycles, 30 cycles, 32 cycles and 34 cycles. Objective 3: Species Specificity - It must be determined if these universal primers do, in fact, bind to all species that possess the genes of interest. Samples from across the different animal classes will be evaluated to determine the specificity of the primers. The primers have already been tested on members of the deer family, with success, so a male deer sample has been sent to be used as a positive control as it shows both genes. Species of interest are mammals, birds and fish as there are many of each that are endangered and identifying the sex of the animal is an important step to identifying the individual animal.Item Evaluation of Y-STR Data Using a Duplex Gender Real-Time PCR Assay on an ABI Prism 7000 SDS Followed by Amplification with Applied Biosystems AmpFLSTR Yfiler PCR Amplification Kit(2007-08-01) Miller, Jennifer J.; John Planz; Arthur Eisenberg; Joseph WarrenQuantification is the process of determining the concentration of DNA in a sample and plays an extremely important role in the processes of amplification and STR typing. A method of quantification is mandated for a laboratory conducting forensic DNA analysis by National Standard 9.3 (1). Furthermore, anytime a forensic laboratory chooses to implement a new or novel methodology for any step in DNA analysis, a laboratory must conduct an internal validation to ensure the quality of method and any results generated on the equipment used within that laboratory are reliable, reproducible, and accurate before the method is utilized for casework analysis (1). Prior to an internal validation, the method or technology must undergo a developmental validation by the developer or manufacturer to determine conditions or limitations of the method or technology on DNA analysis of forensic samples (2). A study has shown that Y-STR results can be obtained even when the quantification of samples yields a value of 0.00ng/μl (4). The issue of the absolute lowest limit of detection in the quantification process versus input DNA concentrations of the unknown samples to yield any valuable Y-STR typing data has not been addressed. A duplex gender assay developed by Nicklas and Buel (3) has a reported detection limit of 0.5pg for the Alu probe of the duplex assay and quantification will be evaluated on a different qPCR platform than originally reported and followed by amplification using Applied Biosystems’ AmpFLSTR Yfiler PCR Amplification Kit to assess quantification limits. The goal of this internship project was to complete a preliminary evaluation of the sensitivity of a quantification methodology on a different qPCR platform under different detection parameters utilizing Y-chromosome DNA in correlation to Y-STR typing results and evaluate the data qualitatively.Item Sensitivity Comparison of an Organic Based DNA Extraction Method to a Silica Based DNA Extraction System Utilizing Carrier RNA and Effects of a Post-PCR Purification Process(2008-12-01) Nguyen, Chau; Arthur Eisenberg; Joseph Warren; John PlanzNguyen, Chau D., Sensitivity Comparison of an Organic Based DNA Extraction Method to a Silica Based DNA Extraction System Utilizing Carrier RNA and Effects of a Post-PCR Purification Process. Master of Science (Forensic Genetics), December 2008, 2008, 84 pp., 24 tables, 9 figures, References, 33 titles. Organic extraction from forensic samples has consistently produced high DNA yields. However, organic extraction is time-consuming and contains many steps where sample manipulation can occur. In this study, sensitivity of organic extraction method is compared to QIAamp DNA Investigator Kit, a silica based extraction utilizing carrier RNA. The results suggested that the QIAamp DNA Investigator Kit is just as sensitive as organic extraction method in obtaining partial and full DNA profiles. The QIAamp DNA Investigator Kit is less time-consuming than organic extraction and can be automated on the QIAcube. The study also studied the reliability of a post-PCR purification kit in obtaining a better DNA profile. The Qiagen MinElute PCR Purification Kit increased the number of loci detected in 65% of samples tested.