Dermal surface in electric and thermal injuries. Observations by scanning electron microscopy

The dermal surface (after enzymatic digestion of the dermo-epidermal junction) in electric and heat lesions is described. There do not appear to be elements that help in forming a precise differential diagnosis. It is possible, however, to differentiate these lesions from all traumatic cutaneous injuries and some limited nontraumatic lesions (e.g., verrucae). Remarkably good preservation of the dermal surface even in an advanced state of decomposition does suggest the possibility of certain diagnosis of electric and heat lesions even when postmortem phenomena have greatly damaged or even totally removed the epithelial part of the skin.     

The simultaneous identification of seminal acid phosphatase and phosphoglucomutase by starch gel electrophoresis

Although elevated acid phosphatase (AP) activity in vaginal fluid is a consistent indicator for semen, differentiation between vaginal AP and seminal AP provides a more meaningful result. Detection of seminal AP in mixtures of vaginal AP, feces, and blood is accomplished by starch gel electrophoresis, employing the substrate thymolphthalein monophosphate as a selective visualization agent. Genetic phosphoglucomutase isoenzymes are simultaneously separated by this method and allow differentiation in some semen/vaginal fluid mixtures.     

The determination of the phenotypes of 3 enzyme systems by the polyacrylamide gel electrophoresis method

Possibility of combined determination of phenotypes of three enzyme system (glyoxylase-1, phosphoglucomutase and 6-phosphogluconate dehydrogenase) in the apparatus with two vertical blocks of polyacrilamide gel (PAAG) was shown. The method is based on the principle of combination of differently composed blocks of PAAG and single universal electrode buffer. High productivity and economy of the method equally with good quality of resulting phoregrams make this method useful for medicolegal practical work.     

The establishment of the presence of feces in stains by agar gel electrophoresis]

An electrophoretic method of feces determination in stains was developed. Method is based on detection of acid phosphatase only in feces since it is not detectable in human blood and other secretions by this method.     

Form variants of globular hyaline microthrombi. Light microscopy, immunohistochemical and scanning and transmission electron microscopy observations

Globular hyaline microthrombi are characterized by their diameter (2-30 micron), globular form, and positive PAS and PTAH reaction. They are a morphologic indicator of disturbed microcirculation and hemostasis, such as that occurring in shock. In two of our cases, we observed large globular hyaline microthrombi, some with central webbed degradation progressing to the formation of closed or open hollow globules. The electron microscopic findings were similar to those observed by other investigators in typical shock bodies. On the basis of the morphologic findings, the authors conclude that degradation phenomena start at the center of globular hyaline microthrombi and can progress to the surface where accelerated fibrinolysis is possible. The cellular elements that other investigators have described as a possible condensation center for fibrin precipitate proved to be structurally intact cells that are apparently located in niches of open hollow globules or in the center of circular hyaline microthrombi. The diagnostic relevance, vitality, and temporal classification are discussed.     

Sequencing of intersecting lines by combined lifting process and scanning electron microscopy

The chronological order in which two intersecting writing or typed strokes were made can be determined for several combinations of writing media by scanning electron microscope (SEM) examination, a lifting and transfer technique using Kromekote paper, or a combination of the transfer technique followed by SEM examination of the remaining material in the intersection. When non-destructive examination cannot provide unambiguous determination of sequence, judicious choice by the document examiner of which technique to use for a given combination of writing media and paper type can be made using known characteristics of the materials involved. The range of line-crossings which can be reliably sequenced is greater using a combined transfer and SEM technique than when the examination is limited to either technique alone.     

Injuries of the large arteries of the brain and vital reactions. An electron microscopy study

In 90 forensic autopsies (Craniocerebral injury, gunshot, stabbing, blow, strangulation, etc.), semithin sections of great arteries were prepared from around 770 Epon blocks and checked for vital reactions at the mural and intimal ruptures. In 21 cases in which death had occurred immediately or soon after the trauma, with three exceptions, there was a subsequent electron microscopic investigation. In all six mural ruptures and in five of ten intimal ruptures, thrombocyte aggregates were found at the rupture margins. In five intimal ruptures, the possibility of the occurrence of preparations injuries had to be considered. In five cases, the results of the histological study were negative. The success rate is limited in principle in such a screening test since there are technical difficulties in preparing serial sections on long vessels. Death was rapid and the thrombocytes were observed to adhere to the injured wall sites immediately after the trauma. The "thrombocyte sign" is thus of substantial importance as the earliest local vital reaction. In two control cases (strangulation), thrombocyte aggregates were found at intimal ruptures of the basilar artery, which were regarded as the results of stretching via the vertebral arteries during attacks to the neck. The healing processes of intimal ruptures and traumatic medial necrosis in incomplete ruptures occurring later in life are discussed. Even if a cadaver is a few days old, the histological findings at the level of the thrombocytes can be evaluated.     

Scanning electron microscopy: application in the identification of diatoms in cases of drowning.

A simple and rapid method is described for processing organ and water samples for the identification of diatoms so that they can be studied and recorded for taxonomic and diagnostic purposes. Samples are treated with concentrated nitric acid; the fluid obtained is centrifuged, and its sediment is dried, coated, and examined under the scanning electron microscope. The method does not alter the morphology of diatoms and allows the study of freshwater and seawater species present in the organs of bodies found in the water, making possible the diagnosis of drowning under specific conditions.     

应用单细胞凝胶电泳测定人血痕淋巴细胞降解的实验研究

目的探讨血痕形成时间与其DNA降解的淋巴细胞出现率的关系。方法应用单细胞凝胶电泳(SCGE)技术结合荧光显微镜和专业的计算机图像分析技术,测定离体72h内不同时间段的血痕中彗星样淋巴细胞出现率。结果获得人离体血液经不同放置时间间隔后,经LUC IA图像分析系统采集得到荧光图像,并获得体现DNA降解趋势的二项式回归方程y=-0.0178X2+2.4623X+8.1098,r2=0.9522,具有高度的统计学意义。结论72h内的人血DNA降解的淋巴细胞出现率与血痕形成时间之间具有高度的线性相关。     

Characteristics of fibrin formation in stab wounds of the skin, determined by scanning electron microscopy

In an investigation on fibrin formation in skin cut wounds on guinea pigs using scanning electron microscopy, it was established that immediately after the infliction of cuts on live animals, a fine, netlike fiber structure of fibrin forms that gradually covers the entire wounded surface. In the period early after the cuts blood-forming elements attach to the fibrin net through numerous fine fibrin fibers, which incorporate a great number of thrombocytes. Postmortem investigations of these wounds showed that the fibrin net formed preserves its structure. It was also established that a fibrin net forms over skin wounds that were inflicted at different periods after death. In the wounds in the early periods after death, the fibrin net formed was very similar to the one established on wounds inflicted on living animals. Our investigation describes some peculiar characteristics of the fibrin net formed in living animals; there is a fine fiberlike net and the quantity is definitely larger. These characteristics permit the establishment of whether the wounds occurred before death and how much time has lapsed since then.     

Comparative identity and homogeneity testing of the mtDNA HV1 region using denaturing gradient gel electrophoresis

A denaturing gradient gel electrophoresis (DGGE) assay has been developed for comparative identity and homogeneity testing of the mtDNA HV1 region. A total of 49 pairs of sequences, each pair differing by a single unique polymorphism, were tested to verify the reliability of the assay. Discrimination between all pairings was achieved as judged by the resolution of the mismatch-containing heteroduplexes from the fully base-paired homoduplexes. In all but two pairings, resolution of the fully base-paired homoduplexes was also obtained. Sequence pairs differing by multiple polymorphisms were also tested and resulted in a greater separation between the homo- and heteroduplexes. Additional information derived from the technique includes the identification of co-amplifying contaminating or heteroplasmic samples in the independent samples lanes. Thirteen heteroplasmic samples, six at positions distinct from those analyzed in the pairwise comparison study, were analyzed and the heteroplasmic positions identified unambiguously by sequencing the excised bands. The technique constitutes a conceptually simple, accurate, and inexpensive test for determining whether two sequences match within the mtDNA HV1 region, while providing a more definitive control for the identification of co-amplifying contaminating or heteroplasmic sequences than is presently available.     

单细胞凝胶电泳检测大鼠死后肝细胞核DNA降解

目的应用单细胞凝胶电泳技术(SCGE)检测大鼠死后肝细胞核DNA降解规律,分析与死亡时间的关系,为早期死亡时间的推断提供新的方法。方法在大鼠死后30h内,每隔3h取肝组织样本进行单细胞凝胶电泳,用共聚焦显微镜摄取彗星图像,应用彗星图像分析软件(IM I1.0)进行图像分析,并作统计学分析。结果死后大鼠的肝细胞在电泳图像上出现明显的彗星形拖尾,其尾长(TL)、尾矩(TM)在一定的时间范围内(0~18h)随死亡时间的延长而逐渐增大,二者均与死亡时间(PM I)呈现一定的相关回归关系。结论单细胞凝胶电泳技术可应用于早期死亡时间的推断。     

Time-dependant changes in the protein spectrum of blood from living and dead persons by means of electrophoresis in cellulose acetate (author's transl)]

Protein electrophoresis on cellulose acetate shows that with increasing hemolysis of ante- and postmortem blood an extragradient in the alpha2-globulin field is created, which influences the relative ratio in the electropherogram. Strong hemolysis causes a fusion of the alpha2- and beta-globulin chains. In order to make a diagnostic interpretation of postmortem blood by means of electrophoresis, it is therefore essential to take into account the degree of hemolysis. Changes in the electrophoretic pattern due to hemolysis correlate best with the period of storage. With regard to timing for forensic purposes, the value is, however, limited.     

Forensic analysis of soil and sediment traces by scanning electron microscopy and energy-dispersive X-ray analysis: an experimental investigation

This paper reports the results of a series of experiments carried out to determine the precision of soil trace comparisons based on elemental peak height ratios determined by energy-dispersive X-ray analysis (EDXRA) in a variable pressure scanning electron microscope (VP-SEM). Experiments were conducted on 'bulk' soil aggregates, ground powders prepared from the <150 microm soil fractions and on smears of both the bulk soil and <150 microm material placed on cotton cloth. X-ray count data were obtained using area scans and spot analyses at different magnifications. The effects on elemental peak height ratios of varying the SEM chamber pressure, beam spot size, emission current and accelerating voltage were also examined. The peak height ratios for oxygen, silicon, aluminium, potassium, calcium and iron were found to show little variation as a function of chamber pressure, spot size and emission current over the ranges examined, but a strong dependency on accelerating voltage was observed. Within-sample variation in results, expressed by the percentage coefficient of variation, was found to be lowest for area scan analyses of the ground <150 microm fractions and greatest for the spot analyses of the bulk soil aggregates and the <150 microm fractions. We conclude that comparison of elemental peak height ratios determined by EDXRA can be a useful tool for rapid screening of soil samples, especially when combined with investigation of other attributes of the soil traces such as colour, fabric and the composition, shapes and surface textures of individual particles or aggregates within the soil traces. If sufficient material is available and can be readily separated without contamination or loss, higher resolution and more precise elemental data should be obtained by methods such as inductively coupled plasma atomic-emission spectrometry (ICP-AES) or mass-spectrometry (ICP-MS).