Detection of microRNAs in DNA Extractions for Forensic Biological Source Identification

Molecular‐based approaches for biological source identification are of great interest in the forensic community because of a lack of sensitivity and specificity in current methods. MicroRNAs (miRNAs) have been considered due to their robust nature and tissue specificity; however, analysis requires a separate RNA extraction, requiring an additional step in the forensic analysis workflow. The purpose of this study was to evaluate miRNA detection in blood, semen, and saliva using DNA extraction methods commonly utilized for forensic casework. RT‐qPCR analysis revealed that the tested miRNAs were consistently detectable across most tested DNA extraction methods, but detection was significantly reduced compared to RNA extracts in some biological fluids. DNase treatment was not necessary to achieve miRNA‐specific results. A previously developed miRNA panel for forensic body fluid identification was evaluated using DNA extracts, and largely demonstrated concordance with results from samples deriving from RNA extracts of semen, blood, and saliva.     

Mucosal Cell Isolation and Analysis from Cellular Mixtures of Three Contributors

In forensic genetic analyses, mixtures of various biological materials are common samples. Micromanipulation, which is performed based on differences in cellular morphology, is an effective method for the isolation of cells from mixtures. In this study, mucosal cell was isolated from somatic cellular mixtures (blood and saliva) based on micromanipulation and a low volume‐PCR (LV‐PCR) platform. One hundred and twenty‐six parallel LV‐PCR processes were performed using an Identifiler^® kit, with 107 reactions yielding single‐source DNA profiles. Among them, 54 full profiles (50%) and 37 partial profiles (13–15 loci) were obtained. Based on the above method, we obtained a single‐source DNA profile from a cigarette butt contaminated by two victims’ blood in a murder case. The generated genotype was used to query a DNA database, and a perfect match was found.     

Estimating Time Since Death from Postmortem Human Gut Microbial Communities

Postmortem succession of human‐associated microbial communities (“human microbiome”) has been suggested as a possible method for estimating postmortem interval (PMI) for forensic analyses. Here we evaluate human gut bacterial populations to determine quantifiable, time‐dependent changes postmortem. Gut microflora were repeatedly sampled from the proximal large intestine of 12 deceased human individuals as they decayed under environmental conditions. Three intestinal bacterial genera were quantified by quantitative PCR (qPCR) using group‐specific primers targeting 16S rRNA genes. Bacteroides and Lactobacillus relative abundances declined exponentially with increasing PMI at rates of N_t = 0.977e^?0.0144t (r² = 0.537, p < 0.001) and N_t = 0.019e^?0.0087t (r² = 0.396, p < 0.001), respectively, where N_t is relative abundance at time (t) in cumulative degree hours. Bifidobacterium relative abundances did not change significantly: N_t = 0.003e^?0.002t (r² = 0.033, p = 0.284). Therefore, Bacteroides and Lactobacillus abundances could be used as quantitative indicators of PMI.     

Evaluation of Direct PCR Amplification Using Various Swabs and Washing Reagents

DNA profiles were generated via direct amplification from blood and saliva samples deposited on various types of swab substrates. Each of the six non-FTA substrates used in this research was punched with a Harris 1.2 mm puncher. After 0.1 μL of blood or 0.5 μL saliva, samples were deposited on each of these punches, samples were pretreated with one of four buffers and washing reagents. Amplification was performed using direct and nondirect autosomal and Y-STR kits. Autosomal and Y-STR profiles were successfully generated from most of these substrates when pretreated with buffer or washing reagents. Concordant profiles were obtained within and between the six substrates, the six amplification kits, and all four reagents. The direct amplification of substrates which do not contain lysing agent would be beneficial to the forensic community as the procedure can be used on evidence samples commonly found at crime scenes.     

59例过敏反应死亡案例分析

目的通过对过敏反应死亡案例分析,探索过敏反应死亡法医学鉴定标准,为法医学鉴定提供依据。方法收集上海地区1998—2008年59例诊断为过敏反应死亡案例,对案例中死者的临床病史、过敏反应临床表现、尸体检验结果等进行分析。结果 59例过敏反应死亡案例中有58例死于药物过敏(其中77.6%为抗生素),正规医院与非法行医各占37.3%和61.0%,过敏症状主要为呼吸困难、颜面发绀等,自接触过敏原至死亡从1 min到3 d,血清总Ig E浓度50~576.92 IU/m L,临床表现和病理解剖检查结果也有明显改变。结论在排除其他死因基础上,综合分析案情、病史、临床表现、尸检结果,可以得出过敏反应死亡的鉴定结论。其中案情调查(包括过临床病史、过敏原接触史、临床表现)对诊断过敏反应死亡具有关键性作用。     

复方"连黄"对金黄色葡萄球菌耐药基因femA的影响

采用聚合酶链式反应(PCR)扩增金黄色葡萄球菌耐药基因femA;通过耐药基因失活试验,研究了中药复方"连黄"对金黄色葡萄球菌耐药基因femA的影响,探讨了中药"连黄"降低金黄色葡萄球菌对β-内酰胺类药物耐药性的作用机理。结果显示,中药"连黄"作用前后金黄色葡萄球菌的耐药基因femA在23~72碱基区发生较大改变,对应的氨基酸序列也发生改变,从而导致femA基因失活。     

浅谈散手运动的速度训练

散手运动作为警察体育的必修科目 ,训练手段和方法日趋完善和科学化。快速的反应、灵巧的动作、飘逸的步伐 ,是散手速度训练的目标。高水平的速度训练 ,为散手运动水平的提高奠定了坚实基础。     

动物产品及饲料中牛源和羊源性成分PCR检测方法的优化

以牛肉、山羊肉为试验材料,对动物产品及饲料中牛源、羊源性成分 PCR检测方法进行了优化。结果,牛源性成分的最低检测限可达 10μg/g,羊源性成分的最低检测限达 0. 1μg/g。PCR检测和酶切鉴定结果表明,在水平测试的混合饲料粉中可检出牛源、羊源性成分。