A study of geo-chemical problems by gas-analytical methods

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Traditional serological methods vs. DNA analysis to detect the presence of semen in sexual assault evidence swabs

Deoxyribonucleic Acid (DNA) analysis is an essential tool for analyzing biological evidence from sexual assault forensic casework. Advances in the sensitivity of DNA quantitation kits and short tandem repeat (STR) analysis have led some forensic laboratories to modify their forensic workflow toward a “direct to DNA” analysis method that eliminates all or some serological testing. Traditional body fluid testing is significantly cheaper and faster than DNA testing, therefore, if biological screening methods can eliminate non-probative samples from the workflow valuable resources can be saved. However, if DNA methods are more sensitive and are a better predictor of the presence of biological material, it could be advantageous to bypass traditional body fluid screening techniques. This study evaluates the sensitivity of presumptive and confirmatory forensic serological screening methods compared to the sensitivity of quantitative real time polymerase chain reaction (q-PCR) and capillary electrophoresis (CE) for semen-positive evidence swabs. Semen samples from four volunteers, one of which was azoospermatic, were obtained and dilutions ranging from 1:10 to 1:8000 were prepared. Neat semen and the dilutions were analyzed using the SERI® AP Spot Test, ABA card® p30 Test, RSIDTM-Semen Test, as well as microscopically examined for spermatozoa aided by Kernechtrot Picrodindigocarmine (KPIC) staining. The serological exam results were compared to DNA quantitation results using the Quantifiler® Trio DNA Quantitation Kit, CE results using the GlobalFiler™ PCR Amplification Kit in conjunction with a SeqStudioTM genetic analyzer, and profile analysis using GeneMapper® ID-X v1.6. Results showed that the AP Spot Test was the most sensitive out of the four serological tests examined. Positive results were observed up to a 1 in 4000 semen dilution if allowed five minutes of development time. However, if only given two minutes to develop, the limit of detection was observed at a 1 in 1000 semen dilution. RSIDTM-Semen yielded positive results for three of four donors at the 1:1000 dilution with the fourth donor providing results only up to the 1:100 dilution. Comparatively, the ABA card® p30 Test and microscopic analysis using KPIC stain had a limit of detection of 1 in 100. The azoospermatic donor showed higher sensitivity than the sperm positive donors, displaying serology results up to a 1:4000 dilution. To assess the comparative sensitivities between serological testing and DNA testing, the 1 in 100, 1 in 1000, and 1 in 2000 dilutions were selected for DNA quantitation and analysis. The DNA quantitation results obtained showed that values suggestive of successful autosomal DNA profiling could be obtained for most 1 in 100 and 1 in 1000 semen dilutions. When samples were analyzed using capillary electrophoresis, full STR profiles were obtainable at the 1 in 1000 dilution for all three sperm-positive donors when using an analytical threshold (AT) of 30 relative fluorescent units (RFU). For one sperm-positive donor, a full profile was obtained at the 1 in 2000 dilution with successful partial profiles obtained from the other two sperm-positive donors. The azoospermatic sample provided full STR profiles up to a 1 in 100 dilution, which was as sensitive or less sensitive than its corresponding serological test results. DNA analysis was more sensitive than serological testing for the sperm-positive samples in this study. Overall, the findings of this study support a “direct to DNA” approach for sexual assault evidence swabs, however it highlights that additional serological examination may be beneficial, particularly in cases involving an azoospermatic donor

Longitudinal link between ADHD and anxiety for children with low social preference : the mediating role of hostile attribution bias

Expression of ADHD symptoms may confer risk for increases in internalizing outcomes over time. One potential explanation is the presence of hostile attribution bias: this social processing deficit has been observed in populations with ADHD and has also been shown to predict increases in anxiety over time in community samples. Given that children with ADHD often experience poor relations with peers, and significant evidence links low social preference and later anxiety, low social preference may experience amplified risk for later anxiety. The current study used a sample of 362 participants to test 1) whether expression of symptoms associated with ADHD in childhood predicts increases in anxious symptoms in emerging adolescence, 2) whether this association is mediated by hostile attribution bias in childhood, and 3) whether social preference in childhood moderates this mediation. Results revealed a significant longitudinal association between ADHD symptoms and increases in anxious symptoms in emerging adolescence, but hostile attribution was not found to mediate this association. Additionally, low social preference was not found to exacerbate risk for later anxiety. Given that findings of the present study were nonsignificant, future research should consider other potential mechanisms of risk from ADHD to later anxious symptoms in order to inform interventions for children with ADHD who may be at risk for developing internalizing symptoms later in development