Internal Validation of Human Mitochondrial DNA Quantification Using Real‐Time PCR

The quantity of mitochondrial DNA (mtDNA) template added for amplification and subsequent dye terminator reactions is critical for obtaining quality sequence data. Validation of a human mtDNA real‐time quantitative PCR (qPCR) assay demonstrated its high degree of reproducibility and precision as well as an extremely sensitive threshold of detection (0.0001 pg/μL or approximately six human mtDNA copies/μL). A study of 35 nonprobative bone and teeth evidence samples revealed that 20 pg of mtDNA template is recommended for successful HV1 and HV2 sequence analysis; however, as little as 0.013 pg can generate a full mtDNA profile when using enhanced amplification reactions. The assay can also detect PCR inhibition and is useful for identifying samples that may benefit from re‐purification. Overall, the assay is an excellent method to quantify mtDNA and is useful for determining the best analytical approach for successful sequencing.     

实时荧光定量PCR检测羊肉制品中鼠源性成分

目的建立基于实时荧光PCR技术的肉制品中鼠源性成分的快速检测方法。方法以羊和鼠的细胞色素b基因序列设计特异性引物和Taqman荧光探针,通过特异性、灵敏性及模拟混合肉样检测实验,建立羊肉制品中鼠源性成分实时荧光定量PCR检测方法。结果该检测方法具有良好的特异性和灵敏度,在50mg羊肉和鼠肉的混合样品检测中,鼠源性成分检测限可低至1%。结论所建立的鼠源性成分检测的实时荧光定量PCR方法,为肉制品质量控制提供了有效的技术手段,弥补了利用RTi-PCR检测肉制品中鼠源性成分的技术空白。     

微滴式数字PCR技术用于生物样品种属鉴定和绝对定量

目的 运用微滴式数字PCR技术进行生物样品的种属鉴定和绝对定量.方法 选择人mtDNA两个编码基因ND4和16S rRNA,设计特异性引物与探针,用人来源及常见动物样本验证种属特异性,再用重组质粒和2组共16份人来源生物检材,倍比稀释.使用微滴式数字PCR技术进行种属检验和绝对定量,验证其灵敏度和稳定性.结果 人重组质粒FAM （ND4）可进行人来源样品的检测,其检测结果与各级稀释梯度基本吻合,微滴式数字PCR技术可以检测出反应体系中低至单拷贝的DNA.结论 微滴式数字PCR技术可以进行生物样品的种属鉴定和绝对定量,并具有很高的灵敏度和特异性,可应用于日常法医物证检验.     

信息时代犯罪定量标准的体系化构建

伴随着信息技术和互联网的迅猛发展,传统的犯罪定量标准体系在信息时代日渐滞后,难以适用于网络空间和网络犯罪。司法实践中对于犯罪定量标准在"点"上有所探索,但是在"面"上整体滞后,缺乏成体系的犯罪定量标准体系,根本无法对于信息时代不断增长和变异的新型犯罪进行公正、高效的定量评价。信息时代犯罪定量标准的整体创建遭遇着惯性阻碍,表现在信息时代犯罪定量标准体系的单一化倾向与数量化倾向。对于网络犯罪创建体系化的犯罪定量标准是当务之急;而创新全新定量标准体系的整体发展路径,是在采用复合化方案与情节化方案。     

Public preferences regarding police facebook posts: a macro-level analysis

ABSTRACT

Police agencies have adopted social media quite widely, but researchers have paid relatively little attention to the phenomenon. To date few studies have explored public reaction to police use of social media. The current study uses a purposive sample with 7,116 police Facebook posts collected from 14 different police agencies during a one-year period to answer two principal research questions: (1) with respect to the number of likes, number of shares, or number of comments regarding different themes present in police Facebook posts, are there differences among police agencies corresponding to differences in the thematic content in their postings? and (2) What factors are related to the public reaction (i.e., likes, shares, comments) to a police Facebook post? The findings from ANOVA and negative binomial regression models clearly indicate that citizens do have definite preferences on police Facebook posts – they are more likely to like and make comments on posts of police personnel and police-public relations, but less likely to share posts of Social Networking Sites. Also, they are more prone to like posts with narratives and pictures, but less likely to favor posts containing hyperlinks. Policy implications and practice guidelines, study limitations, and future research are also discussed.     

Medical examiner response to the drug overdose epidemic in King County Washington: “Real-time” surveillance,data science,and applied forensic epidemiology

As the overdose epidemic overwhelmed medicolegal death investigation offices and toxicology laboratories, the King County Medical Examiner's Office responded with “real-time” fatal overdose surveillance to expedite death certification and information dissemination through assembling a team including a dedicated medicolegal death investigator, an information coordinator, and student interns. In-house testing of blood, urine, and drug evidence from scenes was performed using equipment and supplies purchased for surveillance. Collaboration with state laboratories allowed validation. Applied forensic epidemiology accelerated data dissemination. From 2010 to 2022, the epidemic claimed 5815 lives in King County; the last 4 years accounted for 47% of those deaths. After initiating the surveillance project, in-house testing was performed on blood from 2836 decedents, urine from 2807, and 4238 drug evidence items from 1775 death scenes. Time to complete death certificates decreased from weeks to months to hours to days. Overdose-specific information was distributed weekly to a network of law enforcement and public health agencies. As the surveillance project tracked the epidemic, fentanyl and methamphetamine became dominant and were associated with other indicators of social deterioration. In 2022, fentanyl was involved in 68% of 1021 overdose deaths. Homeless deaths increased sixfold; in 2022, 67% of 311 homeless deaths were due to overdose; fentanyl was involved in 49% and methamphetamine in 44%. Homicides increased 250%; in 2021, methamphetamine was positive in 35% of 149 homicides. The results are relevant to the value of rapid surveillance, its impact on standard operations, selection of cases requiring autopsy, and collaboration with other agencies in overdose prevention.     

Internal validation of reduced PCR reaction volume of the Qiagen Investigator® Argus X-12 QS Kit from blood samples on FTA cards

The onus of proof in criminal cases is beyond any reasonable doubt, and the issue on the lack of complete internal validation data can be manipulated when it comes to justifying the validity and reliability of the X-chromosomal short tandem repeats analysis for court representation. Therefore, this research evaluated the efficiency of the optimized 60% reduced volumes for polymerase chain reaction (PCR) amplification using the Qiagen Investigator® Argus X-12 QS Kit, as well as the capillary electrophoresis (CE) sample preparation for blood samples on Flinder's Technology Associates (FTA) cards. Good-quality DNA profile (3000–12,000 RFU) from the purified blood sample on FTA card (1.2 mm) were obtained using the optimized PCR (10.0 μL of PCR reaction volume and 21 cycles) and CE (9.0 μL Hi-Di™ Formamide and 0.3 μL DNA Size Standard 550 [BTO] and 27 s injection time) conditions. The analytical and stochastic thresholds were 100 and 200 RFU, respectively. Hence, the internal validation data supported the use of the optimized 60% reduced PCR amplification reaction volume of the Qiagen Investigator® Argus X-12 QS Kit as well as the CE sample preparation for producing reliable DNA profiles that comply with the quality assurance standards for forensic DNA testing laboratories, while optimizing the analytical cost.     

大鼠早期缺血心肌中Basigin mRNA的表达

目的检测Basigin mRNA在大鼠早期缺血心肌和非缺血区心肌中的表达差异及探讨其法医学意义。方法建立大鼠早期心肌缺血手术模型,分为EIM组、NIM组、假手术组以及空白对照组,采用real-time PCR方法检测大鼠心肌缺血后15min、30min、1h和2h Basigin mRNA的表达量。结果与NIM组、假手术组及空白组相比,EIM组BSG mRNA表达量在缺血15min时降低,而冠状动脉结扎1h后表达量降低到SO组的一半,此时具有统计学差异(P0.05),结扎2h后表达量恢复至SO组水平。NIM组、SO组和空白对照组之间表达量无统计学差异(P0.05)。结论心肌急性缺血2小时内BSG mRNA表达降低明显,之后升高,说明BSG参与早期缺血心肌自我保护病理生理过程,提示BSG可用于鉴定早期心肌缺血。     

人体脑组织RNA表达水平与早期PMI的相关性

目的探讨人体脑组织多种RNA指标的表达水平与早期死亡时间(PMI)的相关性。方法选取12例已知PMI(4.3~22.5 h)的个体,提取脑组织总RNA。选取8种常用RNA指标(β-actin、GAPDH、RPS29、18S rRNA、5S rRNA、U6 snRNA、miRNA-9、miRNA-125b),通过实时荧光定量PCR技术检测其在脑组织中的表达水平。运用geNorm软件筛选早期PMI表达稳定的内参指标,并分析其表达水平与相关因素(年龄、性别、死亡原因)的关系。运用R软件将内参标准化的RNA指标代入前期研究建立的数学模型推断PMI,计算推断PMI的误差率以验证模型精确性。结果 5S rRNA、miRNA-9和miRNA-125b表达稳定,其表达水平与年龄、性别、死亡原因无关。利用β-actin推断PMI的误差率为24.6%,GAPDH为41.0%。结论 5S rRNA、miRNA-9和miRNA-125b在死亡早期表达稳定,适合作为人体脑组织的内参指标。β-actin表达水平与PMI相关性良好,有望成为推测早期PMI的辅助指标。     

六色荧光标记快速PCR扩增体系的建立及验证

目的建立PCR快速扩增程序和体系,并对其技术指标进行验证。方法采用六色荧光标记技术,对24个常染色体STR基因座、1个Y-STR基因座和Amelogenin、Y-In Del基因座进行复合扩增及毛细管电泳检测,同时考察体系的灵敏度、特异性、同一性、稳定性、混合样本及批量样本测试,并观察各种常见检材及降解、脱落细胞检材的分型情况。结果所建立的体系灵敏度达0.062 5 ng,快速扩增仅耗时65 min就可获得准确分型;种属特异性高;各种纸质血样本和混合、降解、脱落细胞检材的分型正确。结论本研究建立的快速扩增体系可显著提升检验速率,分型准确、稳定,对建立STR数据库、研究群体遗传学和进行法医学鉴定有重要意义。