| 1. |
- Albinsson, Linda, et al.
(författare)
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SKL byter DNA-kit
- 2011
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Ingår i: Kriminalteknik. - Linköping : SKL. ; :1, s. 4-5
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 2. |
- Ansell, Ricky, et al.
(författare)
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Snabbanalysinstrumentet RapidHIT på SKL
- 2014
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Ingår i: Kriminalteknik. - Linköping : Statens Kriminaltekniska Laboratorium. - 1653-6169. ; :1, s. 18-19
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
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| 3. |
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| 4. |
- Boiso, Samuel, et al.
(författare)
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RapidHIT for the purpose of stain analyses – An interrupted implementation
- 2017
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Ingår i: Forensic Science International. - : Elsevier. - 1875-1768 .- 1875-175X. ; 6:Supplement C, s. e589-e590
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Tidskriftsartikel (refereegranskat)abstract
- Rapid DNA instruments have in recent years been developed, enabling analysis of forensic samples with a minimum of human intervention. Initially intended for fast handling of reference samples, such as samples from suspects in booking suites, attention shifted to include crime scene samples. The aim of this study was to determine whether or not the RapidHIT System (IntegenX) is fit for crime scene samples. The first runs gave very poor results, which was found to be due to an incorrect firmware setting leading to no or just minute amounts of amplicons being injected for electrophoresis. After solving this problem, 28 full runs (seven samples each) applying NGM SElect Express were performed comprising various amounts of blood on cotton swabs. Six of the runs failed completely, four due to cartridge leakage and in two runs the PCR mix was not injected. For 155 samples with 1–5ΌL blood (volumes for which complete DNA profiles are expected), 119 samples (77%) gave complete DNA profiles. Among the most serious failures were incorrect allele calling and leakage of DNA extract or PCR product. Other general issues were failure to export results, anode motor breakdown and broken capillary array. Due to the encountered problems with software, hardware and cartridges, together with the low success rate, it was decided not to continue towards implementation of the RapidHIT System in casework.
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| 5. |
- Borgmästars, Emmy, et al.
(författare)
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Improved Detection of Norovirus and Hepatitis A Virus in Surface Water by Applying Pre-PCR Processing
- 2017
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Ingår i: Food and Environmental Virology. - : Springer Science and Business Media LLC. - 1867-0334 .- 1867-0342. ; 9:4, s. 395-405
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) detection of waterborne RNA viruses generally requires concentration of large water volumes due to low virus levels. A common approach is to use dead-end ultrafiltration followed by precipitation with polyethylene glycol. However, this procedure often leads to the co-concentration of PCR inhibitors that impairs the limit of detection and causes false-negative results. Here, we applied the concept of pre-PCR processing to optimize RT-qPCR detection of norovirus genogroup I (GI), genogroup II (GII), and hepatitis A virus (HAV) in challenging water matrices. The RT-qPCR assay was improved by screening for an inhibitor-tolerant master mix and modifying the primers with twisted intercalating nucleic acid molecules. Additionally, a modified protocol based on chaotropic lysis buffer and magnetic silica bead nucleic acid extraction was developed for complex water matrices. A validation of the modified extraction protocol on surface and drinking waters was performed. At least a 26-fold improvement was seen in the most complex surface water studied. The modified protocol resulted in average recoveries of 33, 13, 8, and 4% for mengovirus, norovirus GI, GII, and HAV, respectively. The modified protocol also improved the limit of detection for norovirus GI and HAV. RT-qPCR inhibition with Cq shifts of 1.6, 2.8, and 3.5 for norovirus GI, GII, and HAV, respectively, obtained for the standard nucleic acid extraction were completely eliminated by the modified protocol. The standard nucleic acid extraction method worked well on drinking water with no RT-qPCR inhibition observed and average recoveries of 80, 124, 89, and 32% for mengovirus, norovirus GI, GII, and HAV, respectively.
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| 6. |
- Foreberg, Christina, et al.
(författare)
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High-throughput DNA extraction of forensic adhesive tapes
- 2016
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Ingår i: Forensic Science International. - : Elsevier. - 1872-4973 .- 1878-0326. ; 24, s. 158-163
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Tidskriftsartikel (refereegranskat)abstract
- Tape-lifting has since its introduction in the early 2000's become a well-established sampling method in forensic DNA analysis. Sampling is quick and straightforward while the following DNA extraction is more challenging due to the "stickiness", rigidity and size of the tape. We have developed, validated and implemented a simple and efficient direct lysis DNA extraction protocol for adhesive tapes that requires limited manual labour. The method uses Chelex beads and is applied with SceneSafe FAST tape. This direct lysis protocol provided higher mean DNA yields than PrepFiler Express BTA on Automate Express, although the differences were not significant when using clothes worn in a controlled fashion as reference material (p=0.13 and p=0.34 for T-shirts and button-down shirts, respectively). Through in-house validation we show that the method is fit-for-purpose for application in casework, as it provides high DNA yields and amplifiability, as well as good reproducibility and DNA extract stability. After implementation in casework, the proportion of extracts with DNA concentrations above 0.01ng/μL increased from 71% to 76%. Apart from providing higher DNA yields compared with the previous method, the introduction of the developed direct lysis protocol also reduced the amount of manual labour by half and doubled the potential throughput for tapes at the laboratory. Generally, simplified manual protocols can serve as a cost-effective alternative to sophisticated automation solutions when the aim is to enable high-throughput DNA extraction of complex crime scene samples.
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| 7. |
- Forsberg, Christina, et al.
(författare)
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The need for automation is limited when using a quick and inexpensive one-tube DNA extraction protocol for crime scene samples
- 2019
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Ingår i: Forensic Science International: Genetics Supplement Series. - : Elsevier BV. - 1875-1768. ; 7:1, s. 377-378
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Tidskriftsartikel (refereegranskat)abstract
- Generally, simplified manual protocols can serve as a cost-effective alternative to sophisticated automation solutions. We have developed, validated and implemented a quick, inexpensive and efficient one-tube direct lysis DNA extraction protocol for the majority of our crime scene samples. The method includes one pipetting step, the addition of a lysis buffer based on Chelex beads, Proteinase K and Tween 20. After three incubation steps with vortexing in between, the sample is ready for downstream applications (DNA quantification and STR profiling). The amount of lysis buffer added varies between 200–1000 μL depending on the amount of carrier material in the tube. If needed the extract can be purified or concentrated using a filter device, in our case Amicon Ultra-2. Through in-house validation we show that the method is fit-for-purpose for application in casework for samples containing blood, saliva, shed cells and semen as it provides high DNA yields and high quality STR profiles. The method was implemented at the Swedish National Forensic Centre (NFC) in February 2018. During the first year more than 35,000 crime scene samples were extracted using the method, generating DNA yields equivalent to the previously used method. In conclusion, the need for automation of the DNA extraction process is limited when using a one-tube direct lysis protocol including only the addition of lysis buffer and no transferring steps. In addition it saves costs as there is no need for expensive pipetting robots or service fees and since the reagents used in this direct lysis protocol are relatively inexpensive.
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| 8. |
- Hedell, Ronny, 1985, et al.
(författare)
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Determining the optimal forensic DNA analysis procedure following investigation of sample quality
- 2018
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Ingår i: International Journal of Legal Medicine. - : Springer Science and Business Media LLC. - 0937-9827 .- 1437-1596. ; 132:4, s. 955-966
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 Springer-Verlag GmbH Germany Crime scene traces of various types are routinely sent to forensic laboratories for analysis, generally with the aim of addressing questions about the source of the trace. The laboratory may choose to analyse the samples in different ways depending on the type and quality of the sample, the importance of the case and the cost and performance of the available analysis methods. Theoretically well-founded guidelines for the choice of analysis method are, however, lacking in most situations. In this paper, it is shown how such guidelines can be created using Bayesian decision theory. The theory is applied to forensic DNA analysis, showing how the information from the initial qPCR analysis can be utilized. It is assumed the alternatives for analysis are using a standard short tandem repeat (STR) DNA analysis assay, using the standard assay and a complementary assay, or the analysis may be cancelled following quantification. The decision is based on information about the DNA amount and level of DNA degradation of the forensic sample, as well as case circumstances and the cost for analysis. Semi-continuous electropherogram models are used for simulation of DNA profiles and for computation of likelihood ratios. It is shown how tables and graphs, prepared beforehand, can be used to quickly find the optimal decision in forensic casework.
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| 9. |
- Hedell, Ronny, 1985, et al.
(författare)
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Enhanced low-template DNA analysis conditions and investigation of allele dropout patterns
- 2015
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Ingår i: Forensic Science International: Genetics. - : Elsevier BV. - 1878-0326 .- 1872-4973. ; 14, s. 61-75
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Tidskriftsartikel (refereegranskat)abstract
- Forensic DNA analysis applying PCR enables profiling of minute biological samples. Enhanced analysis conditions can be applied to further push the limit of detection, coming with the risk of visualising artefacts and allele imbalances. We have evaluated the consecutive increase of PCR cycles from 30 to 35 to investigate the limitations of low-template (LT) DNA analysis, applying the short tandem repeat (STR) analysis kit PowerPlex ESX 16. Mock crime scene DNA extracts of four different quantities (from around 8-84 pg) were tested. All PCR products were analysed using 5, 10 and 20 capillary electrophoresis (CE) injection seconds. Bayesian models describing allele dropout patterns, allele peak heights and heterozygote balance were developed to assess the overall improvements in EPG quality with altered PCR/CE settings. The models were also used to evaluate the impact of amplicon length, STR marker and fluorescent label on the risk for allele dropout. The allele dropout probability decreased for each PCR cycle increment from 30 to 33 PCR cycles. Irrespective of DNA amount, the dropout probability was not affected by further increasing the number of PCR cycles. For the 42 and 84 pg samples, mainly complete DNA profiles were generated applying 32 PCR cycles. For the 8 and 17 pg samples, the allele dropouts decreased from 100% using 30 cycles to about 75% and 20%, respectively. The results for 33, 34 and 35 PCR cycles indicated that heterozygote balance and stutter ratio were mainly affected by DNA amount, and not directly by PCR cycle number and CE injection settings. We found 32 and 33 PCR cycles with 10 CE injection seconds to be optimal, as 34 and 35 PCR cycles did not improve allele detection and also included CE saturation problems. We find allele dropout probability differences between several STR markers. Markers labelled with the fluorescent dyes CXR-ET (red in electropherogram) and TMR-ET (shown as black) generally have higher dropout risks compared with those labelled with JOE (green) and fluorescein (blue). Overall, the marker D10S1248 has the lowest allele dropout probability and D8S1179 the highest. The marker effect is mainly pronounced for 30-32 PCR cycles. Such effects would not be expected if the amplification efficiencies were identical for all markers. Understanding allele dropout risks and the variability in peak heights and balances is important for correct interpretation of forensic DNA profiles.
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| 10. |
- Hedman, Johannes, et al.
(författare)
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A fast analysis system for forensic DNA reference samples
- 2008
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Ingår i: Forensic Science International: Genetics. - : Elsevier BV. - 1878-0326 .- 1872-4973. ; 2:3, s. 184-189
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Tidskriftsartikel (refereegranskat)abstract
- On January 1st, 2006, the Swedish legislation on obtaining DNA reference samples from Suspects and the recording of DNA profiles in databases was changed. As a result the number of samples analysed at the Swedish National Laboratory of Forensic Science (SKL) increased from about 4500 in 2005 to more than 25,000 in 2006. To meet this challenge, SKL launched a flew analysis system to create an unbroken chain, from sampling to incorporation of a profile in the national DNA database and subsequent automatic generation of digitally signed hit reports. The system integrates logistics, digital data transfer, new functions in LIMS (ForumDNA Version 4, Ida Infront AB) and laboratory automation. Buccal swab samples are secured on a FTA (R) card attached to an identity form, which is barcoded with a unique sample ID. After sampling, the police officer sends a digital request to SKL. The sample is automatically registered in LIMS and processed on delivery. The resulting DNA profiles are automatically classified according to quality using a custom-made expert system. Building the evaluation around mathematical rules makes it reproducible, standardised and minimises manual work and clerk errors. All samples are run in duplicate and the two profiles are compared within LIMS before incorporation in the database. In the first year of operation, the median time for completion of an analysis was 3 days, measured from delivery of the sample to incorporation of the profile in the national DNA database. In spite of the dramatic increase in the number of reference samples there was no backlog. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
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