The efficacy of Diamond™ nucleic acid dye-stained cell counting techniques for forensic application

IF 1.9 4区医学 Q2 MEDICINE, LEGAL Science & Justice Pub Date : 2024-09-08 DOI:10.1016/j.scijus.2024.09.002

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Abstract

Touch DNA is one of the most common types of biological material collected during criminal investigations. Diamond™ Nucleic Acid Dye (DD) has been shown to aid in touch sample visualisation and target sampling. It has also been used as a method of shedder categorisation that is cheaper and quicker than DNA methods. However, the DD method routinely involves manual cell counting, which can result in intra and inter-person variability similar to other manual techniques used in forensic science, for example, fingerprint identification. Additionally, DD based shedder categorisation involves counting cells in a portion of the touch deposit to extrapolate an individual’s shedder status, and the sampling effect of such estimations is currently unknown.

The present study tested different data analysis aspects of the DD method, including counting variability within and between people, shedder classification differences based on different counting methods (entire thumbprint, sub-section of a print with most cells, sub-section of a print deemed most representative of the entire thumbprint, and random sections), the use of ImageJ software to semi-automate counting and the use and extension of the DD method for investigating DNA Transfer, Persistence, Prevalence and Recovery (DNA-TPPR).

The results of this study show that there are meaningful differences observed during counting processes both between and within people. These differences tended to increase as the factor of time, or the duration of counting, rather than the complexity of cell deposits being assessed. Investment in cell counting software that eliminates personal factors, such as boredom fatigue, can remedy most of these issues, however, will require optimisation, such as fibre recognition. Shedder testing was shown to be affected by the choice of sampling and categorisation methods, and suggested that using an entire finger or larger section size can provide increased precision. Finally, inverted worn gloves stained with DD may provide an acceptable alternative for hands in DNA-TPPR investigations, providing an interesting alternative for future research.

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用于法医应用的 Diamond™ 核酸染色细胞计数技术的功效

触摸 DNA 是刑事调查中最常见的生物材料之一。钻石™核酸染料 (DD) 已被证明有助于触摸样本的可视化和目标取样。它还被用作脱落物分类方法，比 DNA 方法更便宜、更快捷。不过，DD 方法通常涉及人工细胞计数，这可能会导致人与人之间的差异，类似于法医学中使用的其他人工技术，例如指纹识别。此外，基于脱落细胞计数法的脱落细胞分类涉及对部分触摸沉积物中的细胞进行计数，以推断个体的脱落细胞状态，而这种估计的采样效果目前尚不清楚。本研究测试了 DD 方法的不同数据分析方面，包括人内和人与人之间的计数差异、基于不同计数方法的脱落者分类差异（整个拇指指纹、含有最多细胞的指纹的子部分、被认为最能代表整个拇指指纹的指纹的子部分以及随机部分）、使用 ImageJ 软件进行半自动计数以及使用和扩展 DD 方法调查 DNA 转移、持久性、流行性和恢复（DNA-TPPR）。研究结果表明，在计数过程中，人与人之间以及人与人之间都存在有意义的差异。这些差异往往会随着时间因素或计数持续时间而增加，而不是随着被评估细胞沉积的复杂程度而增加。对细胞计数软件进行投资，消除个人因素（如无聊疲劳），可以解决大部分问题，但需要进行优化，如纤维识别。结果表明，脱落细胞检测受取样和分类方法选择的影响，使用整个手指或更大的切片尺寸可提高精确度。最后，在 DNA-TPPR 调查中，用 DD 染色的反戴式手套可以作为手的替代品，为未来研究提供了一个有趣的选择。

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来源期刊

Science & Justice 医学-病理学

CiteScore

4.20

自引率

15.80%

发文量

审稿时长

81 days

期刊介绍： Science & Justice provides a forum to promote communication and publication of original articles, reviews and correspondence on subjects that spark debates within the Forensic Science Community and the criminal justice sector. The journal provides a medium whereby all aspects of applying science to legal proceedings can be debated and progressed. Science & Justice is published six times a year, and will be of interest primarily to practising forensic scientists and their colleagues in related fields. It is chiefly concerned with the publication of formal scientific papers, in keeping with its international learned status, but will not accept any article describing experimentation on animals which does not meet strict ethical standards. Promote communication and informed debate within the Forensic Science Community and the criminal justice sector. To promote the publication of learned and original research findings from all areas of the forensic sciences and by so doing to advance the profession. To promote the publication of case based material by way of case reviews. To promote the publication of conference proceedings which are of interest to the forensic science community. To provide a medium whereby all aspects of applying science to legal proceedings can be debated and progressed. To appeal to all those with an interest in the forensic sciences.