Biomechanical study on the effect of atherosclerosis on the vulnerability of thoracic aorta, and it's role in the development of traumatic aorta injury.

Traumatic aorta injury (TAI) is the second most common traumatic cause of death preceded only by head injuries, being responsible for 5% to 30% of all mortalities in high-speed deceleration injuries. Multiple external factors might play a role such as impact speed, impact direction, occupant location, and presence or lack of restraining safety mechanism. Apart from these external factors, also human biological factors can influence its development. Based on the data of scientific literature, age clearly plays a role in suffering TAI, but the role of atherosclerosis-as a disease affecting the structure of the aorta-is unknown. Biomechanical properties of tissue samples of 104 aorta specimens removed during the autopsy from the posterior (Group 'A') and lateral wall (Group 'B') of descending aorta were analyzed. Specimens were examined by a Zwick/Roell Z5.0 biaxial tester. The Young's modulus (E (MPa)) was calculated using a linear regression procedure where the base of the elongation was the parallel length of the sample, the achieved maximal force (Fmax (N)), the elongation at the time of Fmax (Lmax (mm)), the force at the beginning of rupture (Fbreak (N)), the elongation at the time of Fbreak (Lbreak (mm)) were registered. Specimens were categorized based on macroscopic and microscopic appearance. In the posterior (A) samples the difference between Lbreak (p<0.001) and Lmax (p<0.001) was significant between the macroscopic group. Lbreak (p = 0.009) and Lmax (p = 0.003) showed similar pattern in the lateral (B) samples. Comparing the histological groups by the measured parameters (Fmax, Lmax, Fbreak, Lbreak) showed a significant difference in the means (p<0.001, p = 0.003, p<0.001 respectively). The study demonstrated that atherosclerosis decreases the resistance of the aorta. The rupture occurs at lower force (Fmax and Fbreak), and at shorter elongation (Lmax and Lbreak) in case of the presence of atherosclerosis. This effect is most substantial if calcification is present: the resistance of aorta affected by calcification is only two-thirds on average compared to aorta affected by the early phase of atherosclerosis. This phenomenon can be clearly explained by the weakening structure of the tunica intima.

Phone cam array - An open-source, modular photogrammetry system made of Android phones.

Photogrammetry is a 3D reconstruction technique using photographs of the target from multiple angles. Taking pictures around a static object with a single camera can yield high-quality models, but if the subject moves between images, 3D reconstruction might fail. One way to mitigate this is to use multiple cameras. This project aimed to develop a tool for fast and precise wound documentation for clinical forensic medicine. This paper describes a simple, low-cost modular system, where smartphones of different manufacturers are used as networked cameras. Exposure is initiated at the same time in all the phones with a simple circuit emulating a headset button press. A proof-of-concept device was built, where four phones (Huawei nova 8i (2 pcs), Samsung Galaxy S7 Edge, Oukitel K4000 Pro) were attached to a curved, 3D-printed, handheld frame. The average delay of image capture was 636 ms between the quickest and the slowest phones. When compared to the single-camera approach, the use of different cameras did not reduce the quality of the 3D model. The phone cam array was less susceptible to movement artefacts caused by breathing. Wound assessment was possible based on the 3D models created with this device.

Piercing the surface: A mechanical analysis of stabbing with household tools.

Estimating the applied power during a stabbing incident, or estimating the minimal force necessary to penetrate the body with a certain weapon is a challenging task in forensic practice. A thorough forensic evaluation of stabbing forces needs objective numerical experimental data. Stabbing tests of 12 different weapons - including knives, a pair of scissors, a fork, screwdrivers, a rasp, a corkscrew, and a utility knife blade - were performed with a Mecmesin MultiTest-dV material tester on pork loin and ballistic gel to estimate the stabbing forces and dynamics. Penetration force (Fp ) and maximal force (Fmax ) were recorded, and the registered force curves were analyzed. Fmax was 159.8-212.07 Newton (N), 30.56-30.58 N, 168.9-185.48 N for various knives; 171.39-190.43 N for the pair of scissors, 233.6 N for the fork; 532.65-562.65 N, 370.31-367.19 N and 314.51-432.89 N for various screwdrivers, 44.14-56.62 N for utility knife during pork loin stabbing. The butter knife, corkscrew and rasp were not able to penetrate the pork loin, and the curved fork bent during stabbing. The results prove that weapon characteristics greatly influence the force necessary for penetration. Maximal stabbing force depends mostly on tip sharpness, and the force sharply decreases after penetration occurs, which indicates that edge sharpness is not as important as tip characteristics during stabbing perpendicular to skin surface. The penetration force during stabbing with a pair of scissors is comparable to the penetration force of knives. Stabbing with screwdrivers generally needs larger force than average knives but depends greatly on screwdriver size.

Forensic assessment of a life-threatening penetrating abdominal air gun injury.

Air guns are considered mostly harmless by the public opinion, but projectiles shot from common air guns can penetrate skin and thus able to cause severe, even life-threatening injury. The prevalence of air gun injuries is constantly high, but severe injuries occur rarely. Forensic evaluation of air gun injuries can be challenging since the shot wound characteristics produced by combustion in case of firearm injuries are missing. Despite these difficulties, the topic of air gun injuries is mostly overlooked in forensic literature, and there are no guidelines available which can help the assessment of specific cases. A case of an air gun injury is reported, where the projectile penetrated the abdominal wall and created multiple bowel injury. The complex assessment of all available information (macroscopic and microscopic appearance of entrance wound, types of injuries, CT findings, and crime scene reconstruction) helped to uncover the truth about the circumstances of the injury.

Application of 3D printing in assessment and demonstration of stab injuries.

In stabbing related fatalities, the forensic pathologist has to assess the direction of wound track (thus, the direction of the stabbing) and the weapon's possible characteristics by examining the stab wound. The determination of these characteristics can be made only with a high level of uncertainty, and the precise direction of the stabbing is often difficult to assess if only soft tissues are injured. Previously reported techniques used for the assessment of these wound characteristics have substantial limitations. This manuscript presents a method using today's easily accessible three-dimensional (3D) printing technology for blade-wound comparison and wound track determination. Scanning and 3D printing of knives is a useful method to identify weapons and determine the precise stabbing direction in a stabbing incident without compromising the trace evidence or the autopsy results. Ballistic gel experiment, and dynamic stabbing test experiments prove the method can be applied in safety, without compromising the autopsy results. Identification of the exact knife is not possible with complete certainty but excluding certain knives will decrease the number of necessary DNA examinations, hence it can lower the burden on forensic genetic laboratories. The method addresses many of the shortcomings of previously used methods of probe insertion or post-mortem CT. Insertion of the printed knife into the wound gives a good visual demonstration of the stabbing direction, thus easing the forensic reconstruction of the stabbing incident. After combining the 3D printing with photogrammetry, the achieved 3D visualization is useful for courtroom demonstration and educational purposes.

Sternal aspirate sampling of Bacillariophyceae (diatoms) and Cyanobacteria in suspected drowning cases.

A diagnosis of drowning is not always possible based on the traditional autopsy findings. The most widely used ancillary methods are based on the detection of diatoms and other waterborne organisms in the organs of the systemic circulation by light microscope or polymerase chain reaction (PCR). One of the greatest concerns is sample contamination. Bone marrow is a favourable source because the compact bone protects the sample from water ingress in the case of advanced decay. In our pilot study, we aimed to adopt sternal bone marrow aspiration - which is a widely used technique in haematology - for postmortem sampling. Control experiments of non-drowning victims showed that cleaning the skin over the sternum can prevent external contamination. Sternal aspirate samples were taken from seven suspected drowning victims along with lung, spleen, and femoral bone marrow samples. All specimens were examined for the presence of diatoms by light microscope and Cyanobacteria-specific DNA by PCR. We were able to obtain bone marrow aspirates from all cases without complications. In four of the sternal samples both diatoms and cyanobacterial DNA were detected, while one additional sternum sample was tested positive with PCR, but no diatom shells were detectable. Sternal bone marrow aspiration is simple and quick, which can be performed at the beginning of an autopsy, minimizing the chance of contamination. We have shown that this sampling method can be adopted for postmortem diatom testing. This minimally invasive technique might be used in virtual autopsy (postmortem computed tomography, PMCT) settings without opening body cavities.

Application of photogrammetry in forensic pathology education of medical students in response to COVID-19.

As the coronavirus disease 2019 (COVID-19) pandemic forced universities to switch to distance online education, there was an urgent need to find some virtual/digital alternatives in order to continue teaching. Opportunities such as watching pre-recorded autopsy videos or creating and analyzing post-mortem computed tomography or magnetic resonance imaging with various 3D surface imaging techniques are usually time-consuming and cost-intensive. Photogrammetry, which allows the creation of 3D textured surface models from a series of overlapping photographs taken from varying viewpoints, is a less common approach compared with post-mortem imaging. We created 3D autopsy case models for a special online forensic pathology course in which students could try the models. Then, formal feedback was requested regarding the possible application of this method in education. Most of the students were satisfied with the new method and ranked photogrammetry higher than the other available methods. Our results indicate that photogrammetry has a high potential in undergraduate education, especially in the case of distance education or in those countries where declining autopsy rates have resulted in a decline in the use of the autopsy as an educational tool. Photogrammetry can also be used as a supplementary tool in traditional autopsy-based education and has potential applications in various fields of medical education.

The effect of steatosis and fibrosis on blunt force vulnerability of the liver.

The aim of our study was to examine the possible effect of steatosis and fibrosis on the blunt force vulnerability of human liver tissue. 3.5 × 3.5 × 2-cm-sized liver tissue blocks were removed from 135 cadavers. All specimens underwent microscopical analysis. The tissue samples were put into a test stand, and a metal rod with a square-shaped head was pushed against the capsular surface. The force (Pmax) causing liver rupture was measured and registered with a Mecmesin AFG-500 force gauge. Six groups were formed according to the histological appearance of the liver tissue: intact (group 1), mild steatosis (group 2), moderate steatosis (group 3), severe steatosis (group 4), fibrosis (group 5), and cirrhosis (group 6). The average Pmax value was 34.1 N in intact liver samples (range from 18.1 to 60.8 N, SD ± 8.7), 45.1 N in mild steatosis (range from 24.2 to 79.8 N SD ± 12.6), 55.4 N in moderate steatosis (range from 28.9 to 92.5 N, SD ± 16.0), 57.6 N in severe steatosis (range from 39.8 to 71.5 N, SD ± 11.9), 63.7 N in fibrosis (range from 37.8 to 112.2 N, SD ± 19.5), and 87.1 N in the case of definite cirrhosis (range from 52.7 to 162.7 N, 30.3). The Pmax values were significantly higher in samples with visible structural change than in intact liver sample (p = 0.023, 0.001, 0.009, 0.0001, 0.0001 between group 1 and groups 2 to 6 respectively). Significant difference was found between mild steatosis (group 2) and cirrhosis (group 6) (p = 0.0001), but the difference between mild, moderate, and severe steatosis (groups 2, 3, and 4) was not significant. Our study demonstrated that contrary to what is expected as received wisdom dictates, the diseases of the parenchyma (steatosis and presence of fibrosis) positively correlate with the blunt force resistance of the liver tissue.

Oxidative stress induces transient O-GlcNAc elevation and tau dephosphorylation in SH-SY5Y cells.

O-linked ß-N-acetlyglucosamine or O-GlcNAc modification is a dynamic post-translational modification occurring on the Ser/Thr residues of many intracellular proteins. The chronic imbalance between phosphorylation and O-GlcNAc on tau protein is considered as one of the main hallmarks of Alzheimer's disease. In recent years, many studies also showed that O-GlcNAc levels can elevate upon acute stress and suggested that this might facilitate cell survival. However, many consider chronic stress, including oxidative damage as a major risk factor in the development of the disease. In this study, using the neuronal cell line SH-SY5Y we investigated the dynamic nature of O-GlcNAc after treatment with 0.5 mM H2 O2 for 30 min. to induce oxidative stress. We found that overall O-GlcNAc quickly increased and reached peak level at around 2 hrs post-stress, then returned to baseline levels after about 24 hrs. Interestingly, we also found that tau protein phosphorylation at site S262 showed parallel, whereas at S199 and PHF1 sites showed inverse dynamic to O-Glycosylation. In conclusion, our results show that temporary elevation in O-GlcNAc modification after H2 O2 -induced oxidative stress is detectable in cells of neuronal origin. Furthermore, oxidative stress changes the dynamic balance between O-GlcNAc and phosphorylation on tau proteins.

Hepcidin and its potential clinical utility.

A number of pathophysiological conditions are related to iron metabolism disturbances. Some of them are well known, others are newly discovered or special. Hepcidin is a newly identified iron metabolism regulating hormone, which could be a promising biomarker for many disorders. In this review, we provide background information about mammalian iron metabolism, cellular iron trafficking, and the regulation of expression of hepcidin. Beside these molecular biological processes, we summarize the methods that have been used to determine blood and urine hepcidin levels and present those pathological conditions (cancer, inflammation, neurological disorders) when hepcidin measurement may have clinical relevance.