Ballistic skin simulant

Hydrogels prepared from water solutions containing 10-20 mass% gelatine are generally accepted muscle tissue simulants in terminal ballistic research. They, however, do not have a surface layer which simulates the effect of human skin. The purpose of this research was to find a suitable skin simulant for enhancing the testing fidelity and the credibility of the results with gelatine-based materials when assessing the injury potential of not only high energy bullets, but also especially that of non-penetrating "less lethal" kinetic impact ammunition and relatively low energy ricochet fragments. A skin simulant also permits the simulation and assessment of exit wounds. The mechanical and ballistic properties of human skin and target simulant were established on the basis of results found in the literature. Some errors in these were found. The corrected values are included in this paper for comparison. The target values of the mechanical properties of the skin simulant were the following: threshold velocity v(th)=94+/-4 m/s, tensile strength 18+/-2 N/mm2 and elongation at break 65+/-5%. A selection of synthetic and natural materials was evaluated as skin simulants by analysing their mechanical and ballistic properties. The results were compared to literature values obtained with human cadavers. The tests showed that the best skin simulant of the ones evaluated was semi-finished chrome tanned upholstery "crust" cowhide of 0.9-1.1 mm nominal thickness. Its threshold velocity was 90.7 m/s, tensile strength 20.89+/-4.11 MPa and elongation at break 61+/-9%. These values are the same as the average values of human skin. Of the synthetic materials evaluated, 1mm thick natural rubber can be used on impact side as a threshold velocity filter with some reservations although its theoretical threshold velocity is only 82.9 m/s.     

Caspase与皮肤损伤

Caspase家族,目前已知至少由14个成员组成,该家族成员在细胞凋亡过程中发挥着重要作用。实验研究表明,在皮肤损伤及愈合过程中,伴随着Caspase的活化和表达,这可能与Caspase诱导细胞凋亡的发生有关。深入研究Caspase在皮肤损伤及愈合过程中的作用机制,有望为皮肤损伤的治疗和法医学损伤时间的推断提供新的方法。本文综述了Caspase家族的生物学特性以及Caspase在皮肤损伤及愈合过程中的研究进展,认为Caspase在皮肤损伤及愈合过程中发挥重要作用,具有深入研究的必要。     

Heat thrombosis of burned skin

The vital reaction to heat-induced thrombosis is discussed here using a case of sudden death in the Sauna. The dead body was lying for about one hour in the heat (90 degrees C). Beside the beginning formation of bubbles there was subcutaneous blood vessel exposition, especially in parts outside of the Livor mortis. The cause of death was viral infection with florid Myocarditis.     

Bite mark lesions in human skin

Bite marks in human skin may be found to have been so forcefully made that the skin surface has been disrupted; the marks have become skin lesions. In the following, a case is reported in which such lesions were found on the back of a victim of assault. The dental examiners found it necessary to arrange for a series of simulated bites to be made in order to obtain adequate material for comparison.     

Peroxidase activity in traumatic skin lesions

Peroxidase activity was determined in experimental compression-excoriation lesions and incision wounds of rat skin after different periods of vital time. The peroxidase enzyme was extracted from the tissues by homogenization in 0.5% cetyltrimethylammoniumbromide, and the enzyme activity was measured from the supernatant by o-dianisidine-H2O2 assay. In the blood of the rats a mean activity of approx. 5.26 +/- 1.11 U/g dry weight was observed. In the control specimens of the skin the activity was very low and generally below the detection limit of the methods used. In 30-min-old compression-excoriation lesions the mean peroxidase activity was 0.38 +/- 0.21 U/g dry weight. In lesions older than 30 min the activity started to increase rapidly. In 4-h-old compression-excoriation lesions it was 10 times higher than the 30-min level and was 40 times higher in 12-h-old lesions and 70-100 times higher in 1-3-day-old compression-excoriation lesions, respectively. In 30-min-old incision wounds the mean peroxidase activity was 0.65 +/- 0.37 U/g dry weight. The increase of the activity compared with the 30-min level was even faster in the incision wounds: in 4-h-old wounds the mean activity was 50 times higher, in 12-h-old wounds 200 times higher and in those of 1-5 days it was several hundreds of times higher. Compression-excoriation lesions made after death showed activity similar to the control specimens. Postmortem autolysis at +22 degrees C resulted in a loss of the enzyme activity in 1-day-old compression-excoriation lesions so that after 3 days approx. 80% remained, and after 5 and 7 days approx. 40% was present. After 3 days of autolysis at +4 degrees C, nearly 100% of the activity remained and approx. 90% was present after 5 and 7 days of autolysis. Increased peroxidase activity was also detectable in human vital excoriations in the specimens which were taken in autopsies several days postmortem.     

Micromorphometric parameters of human skin as a marker of skin involution in age determination in forensic medicine

The mathematical analysis of quantitative micromorphometric parameters of different human skin sites on section material has revealed a significant age-related thinning of the skin and its layers, decreased depth of the salivary and sweat glands position. It is proposed to use micrometric skin parameters for expert examination to define a biological age of the examinee.     

Fingerprint recovery from human skin surfaces.

A study was conducted to investigate whether certain dactyloscopic powders and reagents can recover latent fingerprints on human skin surfaces. Four fingerprint powders, Magnetic Jet Black, Magnetic Silver, Silver Special, Swedish Black, and two other methods, cyanoacrylate fuming (CA) and Ruthenium tetroxide (RTX), were used. Having examined skin surfaces with a forensic light source, we observed that the fingerprint impressions remained visible up to 15 min after intentionally placing them on the skin surface of living subjects and dead bodies. Finger marks were recovered and positive results were achieved with Magnetic Black and Swedish Black powder on living subjects. On dead bodies finger marks treated with cyanoacrylate were visible but those treated with RTX, Swedish Black and Magnetic Jet Black powder were useful for potential comparison. On dead bodies best results were obtained with RTX method.     

Analysis of distortion in preserved bite mark skin

In addition to other methods for conservation of bite mark evidence, preservation of actual skin from deceased victims is often suggested. This study was undertaken to analyze the dimensional stability of such specimens. Utilizing a prefabricated template, marks approximating "bites" were made in postmortem skin of Miniature Hanford pigs, producing imprints with distinct margins and indentations. Tissue samples were stored in 10% formalin after affixing an acrylic support ring with cyanoacrylate adhesive and sutures. Measurements of the six tooth mark analogues and cross-arch dimensions were taken at intervals of up to 38 days. Data from these measurements indicate a wide range of amount and type of distortion in preserved tissue. Although some samples were dimensionally stable, there was both contraction and expansion of bite mark specimens, even within individual skin samples. It appears that standard techniques for storage and preservation of bite mark samples will not produce reliable dimensional accuracy.     

来苏儿经皮肤吸收中毒死亡1例分析

某男,69岁,平素身体健康.1999年4月15日因患天疱疮就诊于当地一个体门诊(无行医执照).门诊将酒精20ml来苏儿(市售)40ml和生理盐水混合成500ml左右的液体作为洗液, 将皮炎平1袋、尿素软膏1袋、酒精2ml、来苏儿4ml调配成抹液,治疗的方法是在全身的皮肤上先洗后抹,每天一次,每次均将药液用完.连续治疗3天.其间患者出现皮肤疼痛、浑身发麻、无力、流涎、头疼、眩晕、呕吐、腹痛、腹泻、不能进食,并出现茶色尿.经诊者说这是以毒攻毒,出现这些症状属正常现象.遂继续以同方治疗.3天后,患者出现脉搏细弱 ,面色苍白继而转青紫,出冷汗,呼吸浅慢,体温下降,时有抽搐,且渐加重,出现虚脱、昏迷,经抢救无效死亡.     

Matching the lost skin of a homicide suspect

A case of matching a fragment of lost skin to a homicidal assailant's thumb is reported. The methods used included physical and photographic matching of corresponding configuration and skin ridges, serological blood grouping and enzymes typing. The conclusiveness of such a matching approach is self-evident.     

Gross and histologic postmortem changes of the skin

Many methods have been attempted to accurately and systematically determine the estimated time of death in autopsy cases. Gross changes of the skin which occur during the postmortem interval have occasionally been used to estimate the time of death under different conditions; however, the postmortem gross and histologic changes of the skin have not been systematically analyzed. We sequentially studied the gross and microscopic appearance of skin in 3 individuals during the early postmortem interval (<1 week) in an outdoor, shaded, cool to temperate climate. Photos and skin biopsy specimens were taken from 4 sites (acral skin, scalp, dependent truncal skin, and nondependent truncal skin) every 12-24 hours on each individual. The gross appearance of the skin remarkably did not change significantly in any of the sites after 1 week of decomposition. Three main histologic changes were seen in the skin biopsy specimens: focal dermal-epidermal separation, eccrine duct necrosis, and dermal degeneration. Although bullae were not present in the gross examination of the skin, focal separation of the epidermis from the dermis was appreciated in several skin biopsies; however, the timing of development was unpredictable. Eccrine duct necrosis was another histologic finding and was relatively predictable, occurring in dependent and nondependent truncal skin biopsies from all 3 individuals between days 4 and 7. Dermal degeneration was a uniform histologic finding only in biopsies from nondependent truncal skin, occurring in all individuals on day 2. Although this study is limited by the small number of subjects and uncontrolled extrinsic factors, histologic findings, such as eccrine gland necrosis and dermal degeneration, in select cutaneous biopsies may be useful in estimating the time of death in the early postmortem interval.