Mini-SGM multiplex in degraded samples

A five Mini-SGM multiplex which encompasses TH01, FGA, D18S51, D16S539 and D2S1338, common STR markers in human identity testing, have been performed. Two cases with different biological tissues were selected to illustrate the usefulness of this technique in forensic casework. The use of routine methodology can sometimes give only a partial genetic profile or no profile at all. However, using the Mini-STR technique, a full profile was obtained for the majority of the degraded samples. We conclude that the Mini-SGM methodology is more sensible than routine methodology for degraded samples, although a full genetic profile is not obtained in all cases as results are still very much sample-dependent. This Mini-SGM multiplex can be considered a useful tool to complement conventional STR analysis in degraded samples.     

Y-STR profiling in extended interval (> or = 3 days) postcoital cervicovaginal samples

Depending upon specific situations, some victims of sexual assault provide vaginal samples more than 36-48 h after the incident. We have tested the ability of commercial and in-house Y-STR systems to provide DNA profiles from extended interval (> or =3 days) postcoital samples. The commercial Y-STR systems tested included the AmpFlSTR Yfiler (Applied Biosystems), PowerPlex Y (Promega) and Y-PLEX 12 (Reliagene) products whereas the in-house systems comprised Multiplex I (MPI) and Multiplex B (MPB). Three donor couples were recruited for the study. Postcoital cervicovaginal swabs (x2) were recovered by each of the three females at specified intervals after sexual intercourse (3-7 days). Each time point sample was collected after a separate act of sexual intercourse and was preceded by a 7-day abstention period. As a negative control, a precoital swab was also recovered prior to coitus for each sampling and only data from postcoital samples that demonstrated a lack of male DNA in the associated precoital sample was used. A number of DNA profile enhancement strategies were employed including sampling by cervical brushing, nondifferential DNA extraction methodology, and post-PCR purification. Full Y-STR profiles from cervicovaginal samples recovered 3-4 days after intercourse were routinely obtained. Profiles were also obtainable 5-6 days postcoitus although by this stage partial profiles rather than full profiles were a more likely outcome. The DNA profiles from the sperm fraction of a differential lysis were superior to that obtained when a nondifferential method was employed in that the allelic signal intensities were generally higher and more balanced and exhibited less baseline noise. The incorporation of a simple post-PCR purification process significantly increased the ability to obtain Y-STR profiles, particularly from 5- to 6-day postcoital samples. Remarkably an 8 locus Y-STR profile was obtained from a 7-day postcoital sample, which is approaching the reported time limit for sperm detection in the cervix.     

Automated Quantifiler quantitative PCR setup, template normalization and PCR setup using HID EVOlution™ qPCR/STR setup on trace evidence samples

We have implemented and validated customized protocols for automated Quantifiler^® setup, template normalization and PCR setup using the Tecan HID EVOlution™ qPCR/STR setup. The protocols were validated for the Quantifiler^® human DNA quantification, AmpF?STR^® SGM Plus^® and SEfiler Plus™ PCR Amplification Kits (Applied Biosystems) according to EN/ISO 17025.     

Mini-STRs: A powerful tool to identify genetic profiles in samples with small amounts of DNA

Degraded human remains and crime scene evidences with small amounts of DNA typically reveal incomplete or null genetic profiles when using standard (large) STR amplicons. The technology of mini-STRs, using reduced-size STR amplicons, can help to recover information from these samples. In our Forensic Genetic Service several genetic profiles were obtained or completed using MiniFiler kit (Applied Biosystems) increasing the success rate in sample typing. In all studied cases no inconsistencies were found between profiles obtained with MiniFiler and Identifiler, suggesting that this mini-STR kit can be used to include low copy number (LCN) evidence profiles in STR databases.     

侦查机关强制采取物证比对样本的必要性及合法化路径研究

本文讨论了刑事侦查中强制采取物证比对样本的必要性以及立法规制这种强制活动的必要性,探究了强制采样的合法化路径。认为法律应明确侦查机关有权依照必要性原则、适当性原则和比例原则在侦查中强制采取物证比对样本,并就强制采样的主体、对象、程序等问题作出具体规定,否则,就有可能侵犯相关人员的基本人权。     

Nitrate and Nitrite Determination in Gunshot Residue Samples by Capillary Electrophoresis in Acidic Run Buffer,

Simultaneous determination of nitrate and nitrite in gunshot residue has been conducted by capillary electrophoresis using an acidic run buffer (pH 3.5). In previously developed capillary electrophoretic methods, alkaline pH separation buffers were used where nitrite and nitrate possess similar electrophoretic mobility. In this study, the electroosmotic flow has been reversed by using low pH running buffer without any additives. As a result of reversing the electroosmotic flow, very fast analysis has been actualized, well‐defined and separated ion peaks emerge in less than 4 min. Besides, the limit of detection was improved by employing large volume sample stacking. Limit of detection values were 6.7 and 4.3 μM for nitrate and nitrite, respectively. In traditional procedure, mechanical agitation is employed for extraction, while in this work the extraction efficiency of ultrasound mixing for 30 min was found sufficient. The proposed method was successfully applied to authentic gunshot residue samples.     

型特异性沉淀素血清检验人唾液斑精斑ABO血型的研究与应用

本文介绍了利用型特异性沉淀素血清环状沉淀法检验人唾液斑、精液斑ABO血型的方法与实验结果,并与中和试验及解离试验进行了比较。实验结果表明,本法操作简便,对多种干扰条件下的唾液斑、精斑均具有高度的型特异性,并能从分泌液与血液的混合斑中准确地鉴别出分泌液的血型。本法仅需0.4cm的分泌斑纱线即可进行血型鉴定,其灵敏度高于中和试验而略低于热解离试验,并能有效地检出陈旧分泌液斑中的型物质,因此适于在实际检案中应用。     

Determination of triptolide and wilforlide A in biological samples by LC-MS/MSCSCD

Objective: To determinate triptolide and wilforlide A in biological samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and to verify the method. Methods: After 0.4 mL blood, urine or 0.4 g hepatic tissues with internal standard were extracted by ethyl acetate, they were separated on a Allure PFP Propyl (100 mm × 2.1 mm, 5 μm) with a mobile phase of methanol-20 mmol/L ammonium acetate using gradient elution. For mass spectrometric detection, electrospray ionization (ESP) in positive mode was elected and the data was collected using multiple-reaction monitoring (MRM). Results: The linearity was good (r>0.9950) and the limit of detection was 2 ng/mL or 2 ng/g for triptolide and wilforlide A. The recovery was 61.08%-102.98%. The intra-day and inter-day precision was less than 12.58% for each biological sample, and the accuracy was 90.61%-105.80%. Conclusion: This method is simple, convenient and good selective, and could be applied to analysis of triptolide and wilforlide A in different biological samples. And the method may provide technical support for forensic medicine identification, clinical diagnosis and treatment of tripterygium wilfordii Hook. f. poisoning. © 2015 by the Editorial Department of Journal of Forensic Medicine.     

Beyond the “Narrow Data Base”: Another Convenience Sample for Experimental Research

The experimental approach has begun to permeate political science research, increasingly so in the last decade. Laboratory researchers face at least two challenges: determining who to study and how to lure them into the lab. Most experimental studies rely on student samples, yet skeptics often dismiss student samples for lack of external validity. In this article, we propose another convenience sample for laboratory research: campus staff. We report on a randomized experiment to investigate the characteristics of samples drawn from a general local population and from campus staff. We report that campus staff evidence significantly higher response rates, and we find few discernible differences between the two samples. We also investigate the second challenge facing researchers: how to lure subjects into the lab. We use evidence from three focus groups to identify ways of luring this alternative convenience sample into the lab. We analyze the impact of self-interest, social-utility, and neutral appeals on encouraging study participation, and we find that campus staff respond better to a no-nonsense approach compared to a hard-sell that promises potential policy benefits to the community or, and especially, to the self. We conclude that researchers should craft appeals with caution as they capitalize on this heretofore largely untapped reservoir for experimental research: campus employees.

液相色谱-串联质谱法检测生物样品中百草枯及其代谢物

目的建立生物样品中百草枯(paraquat,PQ)及其2种主要代谢物monoquat,paraquatmonopyridone(MP)的液相色谱-串联质谱(LC-MS/MS)检测方法,应用于百草枯中毒案件的法医学鉴定。方法生物样品经乙腈或甲醇沉淀蛋白,使用Agilent HILIC Plus(4.6×100mm,3.5μm)色谱柱,以0.1%甲酸水溶液～0.1%甲酸乙腈溶液(v/v)为流动相进行洗脱,在多反应监测模式下检测。结果百草枯及其代谢物在1～1000ng/mL内线性关系良好,相关系数(r)≥0.9996,最低检出限为0.34～6.00ng/mL,检测准确度为91.25%～113.44%,日内及日间精密度分别为1.51%～3.99%和1.92%～4.93%。结论本文建立的LC-MS/MS法具有灵敏度高、特异性好的特点,可应用于百草枯中毒相关案件的法医学鉴定。