Forensic applications of sodium rhodizonate and hydrochloric acid: a new histological technique for detection of gunshot residues

Demonstration of the presence of lead residues deriving from gunshot in skin and underlying tissues is essential for the correct forensic analysis of numerous legal cases. Optical microscopy remains the fastest, cheapest diagnostic technique, even though its sensitivity and specificity are poor because of the scarce quantity of histological tissue that can be examined and possible environmental lead pollution. To confirm the presence of lead from gunshot residues, we applied to histological sections of human skin a technique proposed by Owens and George in 1991 for macroscopic detection of lead on the clothing of shooting victims, involving a reaction with sodium rhodizonate and subsequent confirmation by color change on application of HCl. Our results demonstrate the technical possibility of using this macroscopic technique even on histological samples and support the need for further studies on a larger series of cases correlated with the type of ammunition and firing distance.     

Bite marks: physical properties of ring adhesion to skin-phase 1

Abstract: Unsupported excised skin may shrink by as much as 50% or more. In 1981, a method was developed for ring adhesion to skin with the goal of minimizing tissue distortion upon excision. Five modified versions of the technique bearing the author’s name followed (Dorion types I, II, III, IV, and V). The scientific literature reveals little supporting empirical evidence for the preferential use of one adhesive/suturing technique over another. This study compares the use of various bonding materials (Loctite Super Glue gel^®, Dermabond?, Vetbond?), cleaning agents (ethanol, dishwashing liquid, and shaving cream), and depilatory (Veet^®) on the effects of ring adhesion to skin. The conclusions indicate that surface wetness is the most influential factor affecting ring adhesion to skin, followed by the type of bonding material, its “freshness,” and by the cleaning agent used to prepare the skin. The use of a depilatory or shaving cream is to be avoided.     

Evaluation of Skin Surface as an Alternative Source of Reference DNA Samples: A Pilot Study

An acceptable area for collecting DNA reference sample is a part of the forensic DNA analysis development. The aim of this study was to evaluate skin surface cells (SSC) as an alternate source of reference DNA sample. From each volunteer (n = 10), six samples from skin surface areas (forearm and fingertips) and two traditional samples (blood and buccal cells) were collected. Genomic DNA was extracted and quantified then genotyped using standard techniques. The highest DNA concentration of SSC samples was collected using the tape/forearm method of collection (2.1 ng/μL). Cotton swabs moistened with ethanol yielded higher quantities of DNA than swabs moistened with salicylic acid, and it gave the highest percentage of full STR profiles (97%). This study supports the use of SSC as a noninvasive sampling technique and as a extremely useful source of DNA reference samples among certain cultures where the use of buccal swabs can be considered socially unacceptable.     

皮肤烧伤愈合过程中磷酸化c-Jun的表达

目的观察烧伤后人皮肤磷酸化c-Jun(p-c-Jun)的变化特点,初步探讨烧伤后创面愈合的分子机制。方法取12例烧伤后住院植皮患者的烧伤周边区皮肤为实验组;另取正常皮肤12例为对照组。应用免疫组织化学方法和常规HE染色检测p-c-Jun在皮肤烧伤周边区和正常皮肤组织中的变化情况。结果对照组p-c-Jun阳性颗粒主要定位于表皮细胞和内皮细胞中,阳性细胞率为(13.9±2.7)%;实验组p-c-Jun阳性颗粒主要定位于表皮细胞和部分炎细胞中,阳性细胞率上升至(47.2±8.6)%,明显高于对照组(P0.01)。结论烧伤后人皮肤p-c-Jun的表达可能与创面愈合有关。     

大鼠皮肤切创后E-选择素表达及稳定性研究

目的探讨大鼠皮肤切创后E-选择素表达规律及法医学意义。方法健康SD大鼠90只,随机分成4组：正常对照组、活体切创组（30min～7d12个时间点）、死后切创组（30min～3h3个时间点）、死后稳定性组（-20％6h-7d9个时间点,25％6h～3d5个时间点）。在大鼠头部建立皮肤切创模型,按设定的时间点取皮肤检材,运用免疫组化和图像分析技术,检测血管内皮E-选择素的表达规律。结果在活体切创组中,伤后1hE-选择素在血管内皮细胞内即呈阳性表达,持续至伤后7d,且随时间变化呈规律性表达。在正常对照及死后切创组未见阳性表达。死后-20％稳定性组各时间点E-选择素表达与死后即刻比较无显著性差异（P〉0．05）。25％各时间点与死后即刻比较有显著性差异（P〈0．01）。结论E-选择素在创伤后血管内皮细胞内特异性的表达具有时序性规律,且低温条件下稳定性较好。     

小鼠皮肤切创愈合过程中FAP和α-SMA的表达

目的观察小鼠皮肤切创愈合过程中成纤维细胞激活蛋白（fibroblast activation protein,FAP）和α-平滑肌肌动蛋白（α-smooth muscle actin,α-SMA）表达的变化规律。方法应用免疫组织化学和West-ern印迹法检测小鼠皮肤切创后各个时间段FAP和α-SMA表达情况。结果免疫组化结果显示FAP与α-SMA在正常对照组及伤后1h组小鼠皮肤弱表达,伤后6h阳性细胞率开始升高,伤后5dFAP阳性细胞率达高峰,伤后3dα-SMA阳性细胞率达高峰,伤后14dFAP与α-SMA恢复至与对照组相同。Western印迹法检测显示FAP和α-SMA从1d起各个时间段均有表达,其中5d为FAP的表达高峰,3d为α-SMA的表达高峰。结论FAP可作为法医学皮肤切创形成时间的推断指标,α-SMA可作为损伤修复中后期的推断指标,FAP与α-SMA联合使用有望成为推断皮肤损伤时间的有效指标。     

IL-33在小鼠皮肤创伤后损伤时间推断中的作用

目的通过观察白细胞介素-33(interleukin-33,IL-33)在皮肤创伤后的时序性变化规律,探讨IL-33在法医学实践中用于损伤时间推断的应用价值。方法利用直径为5mm的圆形锉刀在小鼠背部建造皮肤损伤模型,于伤后1h、3h、6h、12h、1d、3d、5d、7d、10d取损伤处组织,对照组在与创伤组小鼠相同部位取同等大小的皮肤样本。采用苏木精-伊红(hematoxylin-eosin,HE)染色法观察皮肤创伤后愈合过程中的形态学变化,通过Western印迹法、免疫组织化学染色和双重免疫荧光染色法检测皮肤创伤样本IL-33的表达变化。结果Western印迹法结果显示,伤后3h,IL-33蛋白表达稍有下降,6h后IL-33蛋白表达逐渐增加,于伤后3d达峰值,随后逐渐减少。免疫组织化学染色结果显示,在对照组皮肤的表皮、毛囊、皮脂腺及真皮中固有细胞有少量IL-33阳性表达,伤后3h,IL-33阳性细胞率开始增加,伤后3d达到峰值,随后逐渐减少。双重免疫荧光染色结果显示,伤后1~3d,IL-33阳性表达细胞主要为巨噬细胞,伤后5~7d,IL-33阳性表达细胞主要为肌成纤维细胞。HE染色结果显示该皮肤损伤模型创口愈合过程符合炎症的病理学发展规律。结论IL-33有望成为法医学推断皮肤损伤时间的参考指标。     

大鼠死后皮肤傅里叶变换红外光谱变化与死亡时间的关系

目的运用傅里叶变换红外(Fourier transform infrared,FTIR)光谱技术分析大鼠死后15d内背部皮肤的光谱变化,以此推断死亡时间。方法大鼠麻醉后颈椎脱臼处死,置于温度为25℃、湿度为50%的环境中,分别于不同时间点提取其背部皮肤,收集红外光谱数据,并利用机器学习技术对数据进行分析。结果大鼠死后背部皮肤组织光谱吸收峰的峰位未发生明显改变,其强度随死亡时间延长而发生变化;偏最小二乘(partial least squares,PLS)回归构建的死亡时间推断模型决定系数(R2)为0.92,预测均方根误差为1.30 d。根据模型中的变量投影重要性(variable importance for projection,VIP)指标确定推断死亡时间的贡献波段为1760~1700cm-1、1660~1640cm-1、1580~1540cm-1和1460~1420cm-1。结论应用FTIR技术检测大鼠死后皮肤组织的光谱学改变,为死亡时间推断提供了一种新的思路。     

“易容犯罪”引发的法律思考--以“人皮面具”为视角

近些年来，全国多地发生以“易容”的方式实施盗窃、抢劫、强奸、诈骗等犯罪行为的案件。目前，在中国对“人皮面具”并不是特许管理，而“人皮面具”被不法分子利用给社会带来的安全隐患正日益凸显。针对目前形势，可以借鉴“管制刀具”的管理模式加强对“人皮面具”的管理，从生产源头、销售渠道、使用管理和立法上加强管控，避免被不法分子利用。笔者从“人皮面具”的国际监管出发，借鉴管制刀具的管理经验，试图从法律的视角对“人皮面具”的管理找到出路。     

牛结节性皮肤病防控技术研究现状及其策略

2019年8月我国新疆伊犁地区首次爆发牛结节性皮肤病,为做好该病的防控工作,防止外来疫情扩散蔓延到我国内地,现将该病防控的诊断检测技术、疫苗研发状况以及我国的策略进行概括介绍,为有效控制、净化和根除该病提供指导。