Estimation of Chronological Age from Postmortem Tissues Based on Amino Acid Racemization

Skin and cartilage tissue specimens from 32 male and 13 female corpses aged between 17 and 50 years were collected within 24 h after the death. Each specimen was analyzed for the composition of dextro (D) and levo (L) forms of aspartate, glutamate, and alanine. Linear regression models were constructed using ln [(1 + D/L)/(1 ? D/L] equation to define the relationship between the extent of racemization and the chronological age. Aspartate D/L rates from cartilage showed high correlation (r = 0.779, p < 0.001, n = 45). Aspartate D/L rates from skin showed very low correlation (r = 0.356, p < 0.002, n = 44). The multilinear regression model of both aspartate D/L rates of cartilage and skin tissues in 44 cases yielded a coefficient of r = 0.828 (p < 0.001). In conclusion, only racemization rate of Aspartate both in the skin and the cartilage tissues correlated with the chronological age. Our results may imply that the age can be estimated more precisely if two different tissue specimens are obtained from one corpse.     

The detection of metallic residues in skin stab wounds by means of SEM-EDS: A pilot study

The morphological analysis of stab wounds may often not be accurate enough to link it with the type of wounding weapon, but a further evaluation may be performed with the search for metallic residues left during the contact between the instrument and the skin. In this study, Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) was applied to the study of cadaveric stab wounds performed with kitchen knives composed of iron, chromium and nickel, in order to verify the presence of metallic residues on the wound's edge. Two groups of 10 corpses were selected: group A, including victims of stab wounds and a control group B (died of natural causes). Samplings were performed on the lesions and in intact areas of group A, whereas in group B sampling were performed in non-exposed intact skin. Samples were then analysed with optical microscopy and SEM-EDS. In group A, optical microscopic analysis showed the presence of vital haemorrhagic infiltration, while SEM-EDS showed evidence of microscopic metal traces, isolated or clustered, consisting of iron, chromium and nickel. Moreover, in two cases organic residues of calcium and phosphate were detected, as a probable sign of bone lesion. Control samples (group A in intact areas and group B), were negative for the search of exogenous material to optical microscopy and SEM-EDS. The results show the utility and possible application of the SEM-EDS in theidentification of metallic residues from sharp weapons on the skin.     

Uniqueness of the Dentition as Impressed in Human Skin: A Cadaver Model*

Abstract: Bitemark interpretation assumes that the human dentition is unique and that its attributes can be accurately transferred to skin. A cadaver model was used to investigate whether the correct biter could be determined from similarly aligned dentitions once the dentitions were impressed in human skin. One‐hundred dental stone models, which were measured and determined to be unique, were divided into 10 groups based upon similarities of mal‐alignment patterns. One model was randomly selected from each group and bites were produced on unembalmed human cadavers. Metric/angular measurements and hollow volume overlays of the models were compared with the bites made. The percentage of dentitions from each group as well as the 100 dental model population that could not be excluded as the biter was determined. Results showed difficulty distinguishing the biter from individuals with similarly aligned dentitions and in some cases, an incorrect biter appeared better correlated to the bite.     

小鼠皮肤切创黏着斑激酶和磷酸化黏着斑激酶的表达及其变化规律

目的研究小鼠皮肤切创愈合过程中,黏着斑激酶（focal adhesion kinase,FAK）和磷酸化黏着斑激酶（phospho—FAK,p—FAK）在损伤区及损伤周边区内的表达及其变化规律。方法应用免疫组织化学染色技术和免疫印迹（Western blot）方法观察小鼠背部切创后损伤区及损伤周边区FAK及p-FAK的表达情况。结果伤后3h,FAK和p-FAK主要表达于多核粒细胞;伤后6～24h,主要表达于大部分浸润的多核粒细胞和单核细胞;伤后3～14d。主要表达于单核细胞和成纤维细胞。伤后FAK的阳性细胞率逐渐增高．于3d达到高峰．随后迅速下降;伤后p-FAK的阳性细胞率也逐渐增加,于12h达到高峰,之后逐渐下降。Westernblot结果显示,正常皮肤中FAK及P—FAK均有表达。FAK表达强度变化不是十分明显,但仍可见在3d时含量达到最高。p-FAK蛋白含量伤后逐渐增加．12h表达最强,随后逐渐下降。结论在小鼠皮肤切创愈合过程中,FAK和p-FAK阳性细胞率呈时间规律性变化．可用于皮肤切创损伤时间的推断。p-FAK呈现出明显的时间规律性变化,说明作为皮肤损伤时间的推断指标要优于FAK。     

The Response of Skin to Applied Stress: Investigation of Bitemark Distortion in a Cadaver Model*

Abstract: Knowledge of distortional properties of skin is important in bitemark analysis. Thus, the response of skin to stress from bites was investigated. Four sets of models were created from the dentition of one individual. Anterior teeth were systematically removed to vary contact surface area. A biting apparatus was constructed with an integrated load cell. Forty‐six bites were created perpendicular to Langer lines on six cadavers. Rate of force application and bite pressure were controlled. Metric/angular measurement and hollow volume overlays were employed. Distortion produced by each dentition was calculated and assessed. Results showed that as teeth impressed loose tissue, mesial/distal distance increased, angles of rotation flattened, and inter‐canine distance lengthened. An opposite effect was seen in tight tissue. When the surface area of the dentition was reduced, a mixture of these effects was observed. Conclusions indicated that stiffness of the tissue was the most important variable in bitemark distortion.     

Recovery of Latent Fingerprints and DNA on Human Skin*

Abstract: The project “Latent Fingerprints and DNA on Human Skin” was the first systematic research in Europe dealing with detection of fingerprints and DNA left by offenders on the skin of corpses. One thousand samples gave results that allow general statements on the materials and methods used. The tests were carried out according to a uniform trial structure. Fingerprints were deposited by natural donors on corpses. The latent fingerprints were treated with magnetic powder or black fingerprint powder. Afterward, they were lifted with silicone casting material (Isomark^®) or gelatine foil. All lifts were swabbed to recover DNA. It was possible to visualize comparable and identifiable fingerprints on the skin of corpses (16%). In the same categories, magnetic powder (18.4%) yielded better results than black fingerprint powder (13.6%). The number of comparable and identifiable fingerprints decreased on the lifts (12.7%). Isomark^® (14.9%) was the better lifting material in comparison with gelatine foil (10.1%). In one‐third of the samples, DNA could be extracted from the powdered and lifted latents. Black fingerprint powder delivered the better result with a rate of 2.2% for full DNA profiles and profiles useful for exclusion in comparison with 1.8% for the magnetic powder traces. Isomark^® (3.1%) yielded better results than gelatine foil (0.6%).     

不同环境条件下大鼠皮肤死后大体和组织学改变

死亡时间的推测是法医病理学研究的重点和难点,对晚期死亡时间的推断误差较大。皮肤是机体死后分解破坏发生较迟的部分。不同环境条件下死后不同时间大鼠皮肤大体、组织学的改变,为推测较长的死后间隔时间建立实验动物依据。利用皮肤大体、组织学改变可望较系统和准确地推测晚期死亡时间。     

手区胃影像图监测胃黏膜寒热变化研究

目的 求证寒热食物与手区胃影像图变化的关联性。方法 采用验证医学模式,采用寒热食物对胃黏膜进行刺激,观察手区胃影像图的变化。结果 寒热对胃黏膜的刺激致使手区胃影像图迅速产生动态响应,寒性食物使手区胃影像图增加白色和青色成分,热性食物使手区胃影像图增加红色成分。结论 手区胃影像图是胃黏膜色泽映射成像的客观表达,寒热是导致胃黏膜色泽发生改变的主要因素之一,手区胃影像图技术可成为验证胃黏膜寒热变化的客观工具。     

载黄芪多糖组织工程支架促糖尿病大鼠皮肤创伤修复研究

目的 研究载黄芪多糖（Astragalus polysaccharides,APS）组织工程支架(APS/PDLGA)对糖尿病大鼠皮肤创面愈合的影响。方法 采用高压静电纺丝技术制备APS/PDLGA超细纤维,构成三维纤维网状组织工程支架;扫描电子显微镜观察纤维形貌,并计算直径;采用苯酚-浓硫酸法检测载药量与包封率;将APS/PDLGA用于糖尿病大鼠皮肤溃疡创面修复,采用苏木精-伊红染色观察各实验组皮肤修复进程。结果 APS/PDLGA纤维表面光滑、粗细均匀、直径（2.56±0.50）μm、载药量（5.22±0.076）%、包封率（90.06±1.31）%,覆盖APS/PDLGA纤维膜组的糖尿病大鼠皮肤创面约在第18天完全愈合,新生上皮外观与结构和正常皮肤相似,愈合速度明显快于空白PDLGA纤维膜组和对照组创面（P＜0.01）。结论 APS/PDLGA纤维组织工程支架可促进糖尿病大鼠皮肤创面愈合,有望应用于糖尿病皮肤溃疡治疗。     

婴儿手的色泽与手区胃信息影像表达关系研究

目的 研究手区胃影像图基准值的“测量基准”和校验方法。方法 以中西医理论为指导,采用验证医学模式,首先模拟健康胃黏膜的手区胃影像图,然后对10个健康婴儿手色泽的影像图进行分析。结果 健康婴儿整体上最接近健康胃黏膜的标准,健康婴儿的手区胃影像图与健康胃黏膜的手区影像模拟图是相符的,样本与理论推论结果得到互证。结论 以健康婴儿手的色泽为手区胃影像图基准值的“测量基准”是科学的,且易取材。