Scanning electron microscopy of incinerated teeth

The aim of the present scanning electron microscopy study was to document the nature of morphologic changes occurring in human enamel and dentin subjected in vitro to temperatures in the range of 200-1,000 degrees C for variable times. The results of the investigation confirm that human enamel and dentin remain microscopically identifiable after incineration at 1000 degrees C. Furthermore, these tissues remain identifiable after incineration at 1,000 degrees C for periods greater than 3 h. No consistent or reliable differences in morphology could be detected in enamel or mineralized dentin incinerated in the temperature range 200-600 degrees C. Temperature-dependent changes involving the predentin zone were observed. Following incineration at 800 degrees C for over 3 h and at 1,000 degrees C for 3 h, a metamorphosis of enamel and dentin into a globular form was observed.     

Scanning electron microscopy analysis of experimental bone hacking trauma

The authors report on their macro- and microscopy study of bone lesions made by a sharp force instrument (a single blade knife), and a sharp-blunt instrument classified as a chopping weapon (a hatchet). The aim of this work was to attempt to identify the instrument by analyzing the general class characteristics of the cuts. Each weapon was used on human bones. The results indicate that macroscopic analysis is more problematic. The microscopic analysis assessed that characteristics examined were effective in distinguishing sharp from sharp-blunt injury to the bone. The microscope facilitates analysis unachievable with macroscopic methods, some three-dimensional characteristics not visible to the naked eye being clearly defined with its use. Emphasis has been placed on the value of SEM as an anthropologist's tool in bone lesion injuries.     

Scanning electron microscopy determination of string mozzarella cheese in gastric contents

As part of a suspected homicide investigation, a sampling of the gastric contents from the victim was forwarded to the U.S. Food and Drug Administration's Forensic Chemistry Center (FCC) for analysis of specific, selected components. The victim was known to have consumed string mozzarella cheese, as a snack, less than 24 h before his disappearance and the subsequent discovery of the body. The investigation sought to confirm or dismiss speculation the victim may have been fed a meal or eaten additional food prior to his death. Analysis of the stomach contents involved examination by stereoscopic light microscopy (SLM) and isolation, processing, and analysis of suspect materials by scanning electron microscopy (SEM). Several wax-like, off-white to cream-colored objects were noted by SLM examination and removed from the gastric contents. Through a series of fixation, sectioning, drying, and coating steps, these objects were prepared for analysis by SEM. Comparison of the suspect material with laboratory control string mozzarella cheese showed excellent correlation between the analyzed samples, confirming the suspect material from the stomach contents as string mozzarella cheese.     

Scanning electron microscopy analysis of experimental bone hacking trauma of the mandible

The authors report on a macroscopic and microscopic study of human mandible bone lesions achieved by a single-blade knife and a hatchet. The aim of this work was to complete the previous data (scanning electron microscopy analysis of bone lesions made by a single-blade knife and a hatchet, on human femurs) and to compare the lesions of the femur with those of the mandible. The results indicate that the mandible is a more fragile bone, but the features observed on the mandible are quite similar to those previously observed on the femur. This work spells out the main scanning electron microscopy characteristics of sharp (bone cutting) and blunt (exerting a pressure on the bone) mechanisms on human bone. Weapon characteristics serve to explain all of these features.     

Scanning electron microscope study of the lung in drowning

The authors describe the results obtained using the scanning electron microscope (SEM) to study drowned lungs and control lungs. Results are compared with a previous study carried out using laboratory animals. The results from both studies are analogous, in the absence of chronic pulmonary emphysema. The diagnosis of chronic pulmonary emphysema is simple with the SEM even when dealing with autoptic material obtained 24 to 48 h after death, but the diagnosis of drowning becomes difficult in lungs with chronic emphysema.     

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.     

Scanning electron microscopic analysis of skin resolution as an aid in identifying trauma in forensic investigations

The forensic investigator is frequently confronted with cases that present with wounds and blunt force trauma. Presently, the forensic investigator depends upon previous experience and further investigative deduction of the crime scene to analyze these injuries. Although not readily apparent to the naked eye, many skin tissue injuries can be visualized with scanning electron microscopy (SEM). This study was designed to establish skin trauma resolution using SEM in various skin preparations. Tissue trauma was induced on leather, preserved skin, fresh skin, and living skin using dies of varying thread size. Calibrated pressure forces in pounds per square inch (psi) were applied and impressions made using vinyl polysiloxane. Positive replicas of the tissues were prepared for SEM using isocyanate resin. After sputter coating the cast with 35 nm of gold-palladium, electron micrographs were generated using a Jeol JSM-5310LV scanning electron microscope. To establish resolution, thread widths of 52, 104, and 208 threads per inch (tpi) and trauma forces of 150, 200, and 250 psi were used to produce the impressions. Microgrooves that were identified on the die threads were analyzed. The optimum pressure for resolution studies was 150 psi using the 52 tpi die on the leather sample (4.67 +/- 0.88 microm, p = 0.046 and 0.025, respectively, by ANOVA). The resolution was compared to that of leather using preserved, fresh, and living skin. The resolution in preserved and fresh skin was less than for leather (9.00 +/- 1.73 and 10.5 +/- 4.5 versus 4.67 +/- 0.88 microm, p = 0.09 and p = 0.20, respectively). Living skin resolution was 3 microm at 52 tpi and 100 psi. Various implements of blunt force trauma were also examined using the leather sample. Time after trauma resolution was examined at 0 (3 microm), 5 (6 microm), 10 (8 microm), and 20 (9 microm) min in living tissue. A comparison between the microgrooves on the die replicas and the tissue trauma impressions revealed striking agreement for both linearity and resolution. Analysis of the microgrooves suggests that discrete morphological characteristics are seen in skin tissue traumas. This method could expand the tools available for the forensic investigation of blunt force trauma.     

The ultrastructure of the electric burn in man: a transmission electron microscopy-scanning electron microscopy study

The authors describe the ultrastructural aspects of the electric burn observed with the transmission electron microscope (TEM) and the scanning electron microscope (SEM). With the TEM the most apparent feature is the homogenization and arrangement of the filamentous cytoplasmic material in elongated and parallel bundles together with elongation of the nuclei and junctional structures. SEM studies present a three-dimensional vision of the filamentous material that confirms and clarifies the cellular deformation as a whole. An hypothesis is advanced suggesting that the phenomenon is due to the effects produced by the extremely rapid dehydration of the tissue or that the electric current and Joule effect can act upon the filaments and contractile proteins, causing the cell deformation.     

Incised wound margins caused by steel blades. Scanning electron microscopy to determine wound direction

The aim of this paper has been to check the diagnostic ability of Scanning Electron Microscopy (S.E.M.) to determine wound direction. We have studied incised wound margins caused by steel blades in human skin samples from cadavers by S.E.M. It was found that a lateral accessory tail existed in 65% of the entrance edges. This finding was recorded in all the cases when wound direction was perpendicular to Lancer's lines of the skin area in which the wound was located. No similar finding in the exit tails was noticed. The depth and length of the wound margins was less accurate an index of the wound direction than a lateral accessory tail. We think that this finding could be useful in determining the entrance margin in incised wounds.     

纳米磁珠提取法在骨骼DNA提取中的应用

目的对纳米磁珠法提取纯化骨骼DNA的效果进行比较评价,为方法选择提供应用参考。方法取泥土掩埋、水中浸泡1~10年不等的25根长骨,经水洗、刮净,液氮冷冻研磨器将骨骼研磨成粉末状,分别应用纳米磁珠提取法和King Fisher仪器自动化提取法提取DNA,IdentifilerPlus试剂盒进行扩增,ABI 3100遗传分析仪进行STR分型检测;对两种方法提取的DNA定量和经扩增、分型检测的结果进行比较。结果骨骼样本采用纳米磁珠法提取到的样本DNA(1.237 5ng/μL±0.319 2ng/μL),较之King Fisher法的浓度(0.506 2ng/μL±0.280 5ng/μL)更高,两种方法间差异具有统计学意义(P0.05);而纳米磁珠法的分型成功率亦更高,两种方法间差异具有统计学意义(P0.05)。结论用纳米磁珠提取纯化骨骼DNA,能得到高质量DNA模板,有利于提高分型检验的成功率,可在实际检案中选择使用。     

Adjunctive use of scanning electron microscopy in bite mark analysis: a three-dimensional study

An examination of a case in which adjunctive use of scanning electron microscopy (SEM) demonstrated the presence of unusual three-dimensional characteristics in a bite mark. Despite the fact that many bite marks do not show "depth," demonstration of the presence of this third dimension can produce significant data for evidentiary purposes. In some instances, these data may transform what seem to be class characteristics of a bite mark into individual characteristics and thus impart much more uniqueness to the evidence. Because of the high level of resolution and magnification of SEM, some three-dimensional characteristics not visible to the eye can be shown quite clearly by its use. Emphasis will be given to the value of SEM as a tool of the forensic odontologist in bite mark analysis.     

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.     

Evaluation of exhibits from a murder case using the lead isotope method and scanning electron microscopy

We have used a combination of lead isotopes and scanning electron microscopy to determine the relationships between different exhibits in a murder case. Samples involved lead projectiles removed from the deceased's head and a pillow, lead-rich scrapings and particles (gunshot residues) from spent cartridges and a silencer, and particles from a pillowcase. The lead projectiles had the same isotopic composition. with the lead being derived from the same dominantly geologically old source(s). The lead smear from the silencer had the same isotopic composition as the projectiles, and the lead was probably from the same source. The particles from the spent cartridges had varying elemental compositions ranging from PbO to PbCuZn +/- Ba with or without Si and are consistent with derivation from the primer. The lead isotopic compositions of the particles from the spent cartridges show some variations, but these are markedly different from those of the projectiles, indicating lead from a mixture of geologically old and geologically young lead. The particles from the pillowcase were extremely small (usually <50 microm size) and showed varying isotopic compositions, some consistent with the gunshot residue from the cartridges. As the exhibits had been handled extensively prior to the present investigation, including some being sent to North America, there is a high likelihood that handling was not done in clean room environments and may have been contaminated. In this instance, as we were concerned about contamination, especially of the pillowcase, we felt contamination negated use of the results for assistance in proving the innocence or guilt of the accused. A combination of high-precision lead isotope measurements with scanning electron microscopy provides a powerful tool for forensic investigations if precautions are taken in handling the exhibits.