Postmortem Human Subjects Research Articles

Responses of side impact dummies in sled tests

Sled tests were conducted at a velocity of 6.7 m/s using side impact dummies (SID, BioSID, ES-2, and WorldSIDp) and the resulting biomechanical responses were compared with responses from post mortem human subjects (PMHS). Initial impact conditions were with and without pelvic offset in combination with and without padding on the impacting wall. Impact forces, thoracic trauma index, chest compression, and viscous criteria were evaluated. The probability of injury was estimated and rates of deformation were computed for each body region. Dummy responses were not always similar in terms of trend and injury criteria when compared with PMHS tests under the same initial conditions. Response variations will be of value in improving the biofidelity characteristics of dummies for crashworthiness evaluations.

New Biofidelic Corridor and Biofidelity Test Procedure for Pedestrian Legform Impactors

The objectives of this research are to propose a new impact response corridor for the ISO legform impactor and to determine the biofidelity of the current legform impactor with rigid leg and thigh developed by the Transport Research Laboratory (TRL). The latest data obtained from Post Mortem Human Subject (PMHS) knee impact tests were analyzed in connection with the proposal, and biofidelity legform impact tests were conducted using the current rigid legform impactor. New normalized biofidelic corridors of impact force corresponding to adult male 50th percentile (AM50) are proposed. The impact test results indicate the current rigid legform impactor does not have sufficient human knee biofidelity. The present results suggest that human tolerance can not be used directly for the injury reference value of the legform impactor. A conversion method is needed to interpret the data measured by current legform impactors as the injury reference value.

Force and Acceleration Corridors from Lateral Head Impact

This study was conducted to provide force and acceleration corridors at different velocities describing the dynamic biomechanics of the lateral region of the human head. Temporo-parietal impact tests were conducted using specimens from ten unembalmed post-mortem human subjects. The specimens were isolated at the occipital condyle level, and pre-test x-ray and computed tomography images were obtained. They were prepared with multiple triaxial accelerometers and subjected to increasing velocities (up to 7.7 m/s) using free-fall techniques by impacting onto a force plate from which forces were recorded. A 40-durometer padding (50-mm thickness) material covering the force plate served as the impacting boundary condition. Computed tomography images obtained following the final impact test were used to identify pathology. Four specimens sustained skull fractures. Peak force, displacement, acceleration, energy, and head injury criterion variables were used to describe the dynamic biomechanics. Force and acceleration responses obtained from this experimental study along with other data will be of value in validating finite element models. The study underscored the need to enhance the sample size to derive probability-based human tolerance to side impacts.

Identification of the protein disulfide isomerase family member PDIp in experimental Parkinson's disease and Lewy body pathology

Parkinson's disease (PD) is a slowly progressing neurodegenerative disorder with no clear etiology. Pathological hallmarks of the disease include the loss of dopaminergic neurons from the substantia nigra (SN) and the presence of Lewy bodies (LBs) (α-synuclein and ubiquitin-positive, eosinophilic, cytoplasmic inclusions) in many of the surviving neurons. Experimental modeling of PD neurodegeneration using the neurotoxins 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenyl-pyridinium (MPP +) has identified changes in gene expression of different endoplasmic reticulum (ER) stress proteins associated with MPTP- and PD-related neurodegeneration. We show that the protein disulfide isomerase (PDI) family member pancreatic protein disulfide isomerase (PDIp), previously considered exclusively expressed in pancreatic tissue, is uniquely upregulated among PDI family members within 24 h following exposure of retinoic acid (RA)-differentiated SH-SY5Y human neuroblastoma cells to either 1 mM MPP + or 10 μM of the highly specific proteasome inhibitor lactacystin. RT-PCR confirms PDIp expression in brain of post-mortem human PD subjects and immunohistochemical studies demonstrate PDIp immunoreactivity in LBs. Collectively, these findings suggest that increased PDIp expression in dopaminergic (DA) neurons might contribute to LB formation and neurodegeneration, and that this increased PDIp expression may be the result of proteasome impairment.

Reconstruction analysis for car–pedestrian accidents using a computer simulation model

Since the 1980s, Japan Automobile Research Institute (JARI) has been developing computer simulation models in order to analyze car–pedestrian accidents and has been validating the models with full-scale car–pedestrian tests with Postmortem Human Subjects (PMHSs). This report presents reconstructions of real-world car–pedestrian accidents using the latest JARI pedestrian model and demonstrates the possibility of in-depth case studies on car–pedestrian accidents.

The internal jugular vein valve may have a significant role in the prevention of venous reflux: evidence from live and cadaveric human subjects.

The internal jugular vein valve (IJVV), which is situated just above the termination of the internal jugular vein, is the only valve between the heart and the brain. This means that it plays a role in the prevention of cephalad flow of venous blood. If the IJVV is damaged or becomes incompetent, increase in intrapleural pressure could result in raised intracranial pressure. Additionally, the jugular venous pulse (JVP) is used clinically to estimate right atrial pressure, a functional IJVV may prevent accurate estimation of the JVP. To describe the presence and the competence of the IJVV in post-mortem and live human subjects. DESIGN - setting and methods: The anatomical appearance of the IJVV from 30 cadavers was studied. Competence was checked by measuring maximum hydrostatic pressure before reflux occurred through the valve. The function of the valve was evaluated in 25 live subjects using colour duplex scanning. The IJVV was present in all cadavers just before its termination (60 IJVVs from 30 subjects). The valve was bicuspid in most cases (93%). The competence of 41 IJVVs was checked of which only three (7%) were found to be incompetent. All IJVVs in live subjects were found to be competent. This study confirms that a functional IJVV is present just above the termination of the internal jugular vein. The IJVV may therefore prevent reflux of venous blood from the right atrium into the internal jugular vein.

Numbers of neurons and non-neuronal cells in human trigeminal ganglia

We analyzed both trigeminal ganglia of eight post-mortem human subjects for their content of neurons and non-neuronal cells using dissociated cell suspension techniques. Neuronal counts in each of the 16 ganglia ranged from 20,000 to 35,400, with an average of 27,400± 4800, and the estimated ratio of non-neuronal to neuronal cells was 100 to 1. Our numbers are comparable to the lower ranges obtained using different techniques in previous studies. [Neurol Res 2000; 22: 565-566]

Pressure measurements in the spinal canal of post-mortem human subjects during rear-end impact and correlation of results to the neck injury criterion

The aim of this study is to validate the pressure effect theory on human beings during a realistic rear-end impact and to correlate the neck injury criterion to pressure in the spinal canal. Sled experiments were performed using a test setup similar to real rear-end collisions. Test conditions were chosen based on accident statistics and recordings of real accidents. In particular, velocity change and acceleration level were reproduced similar to actual collisions. The head restraint as well as the seat back were adjusted to different positions. Two small pressure transducer were implemented to the spinal canal of postmortem human subjects and pressure measurement similar to the pig experiments (using exactly the same equipment) were performed. A total set of 21 experiments with four different subjects were performed. The subjects were additionally instrumented with triaxial accelerometers that allowed for calculation of the NIC criterion. Results showed that NIC and pressure amplitudes of the CSF correlate well and therefor NIC seems to be able to predict these amplitudes also for human beings. Conclusions whether these pressure effects induce soft tissue neck injuries or not could not be drawn and should be investigated in further research.

Detection of lymph and blood vessels in the human intervertebral disc by histochemical and immunohistochemical methods

Twenty-four intervertebral discs from the lumbar region of postmortem human subjects were investigated by immunohistochemical and histochemical methods to evaluate the pattern of blood and lymph vessels of the discus intervertebralis and surrounding tissue at different ages. Antibodies against the basement membrane component laminin, and the lectin Ulex europaeus agglutinin as a marker for L-fucose in endothelial cells, were used to make the blood vessels visible. The 5'-nucleotidase activity in lymph endothelium served as a marker for lymphatic vessels. The dorsolateral parts of the connective tissue adjacent to the discus intervertebralis were well vascularized in all age groups examined. Vessels in the outer anulus fibrosus were detected in young individuals up to 20 years of age. Vascular canals, i.e. blood vessels in the cartilage end plate, were seen up to 7 years of age. Lymph capillaries are first described here penetrating the disc and peridiscal tissue and accompanying most of the small blood vessels into the areas specified.

Biochemical evidence for existence of immunoreactive renin in human prolactinoma tissue

High activity of renin was demonstrated in human prolactinoma tissue. This activity was almost completely inhibited by specific antibody raised against human renal renin, indicating that it was not due to the nonspecific action of proteases. The specific activity of renin was 5.04 ng of angiotensin I generated/mg of protein per h, comparable to that of the pituitary tissue prepared from postmortem human subjects. The biochemical properties of the prolactinoma renin were generally similar to those of well-known kidney enzyme, such as molecular mass (Mr=46, 000), optimum pH (6.0), and glycoprotein nature. However, the isoelectric points (pI) of the prolactinoma renin pI=4.90, 5.04, 5.24 and 5.41) differed somewhat from those of plasma and kidney renins reported hitherto. These results indicate that true renin can be produced in human prolactinoma tissue.

Multiple forms of immunoreactive renin in human pituitary tissue

Immunoreactive renin was demonstrated in pituitary tissues of post-mortem human subjects with different diseases. The specific immunoreactive renin activity comprised the majority of the tissue renin-like activity (mean, 83%), indicating the absence of nonspecific actions of proteases such as cathepsin D. We used three pituitary specimens with high levels of the specific renin activity for further biochemical characterization of the enzyme. Small differences were found in the molecular mass (45 K, 42 K and 37 K), binding to concanavalin A-Sepharose, and isoelectric points (pI) (4.72, 4.78, 4.86, 5.06, 5.28 and 5.44). These results seem to be interpreted as evidence for the presence of specific renin in the human pituitary with microheterogeneity.

Commercial thermoelectric generator applications and economic considerations

The effect of posture and subject-specific factors on injury outcome is an active field of research in injury biomechanics, in particular in automotive safety research where post-mortem human subjects (PMHS) are used as surrogates. Current PMHS tests routinely include acquisition of the subjects׳ geometry and kinematics. However, combining these two datasets to better understand the injury mechanism is still a challenge. This study investigated the connection between pre-impact posture and resulting injuries in six previously published side impact sled tests (three with a rigid wall and three with an airbag) by creating three-dimensional kinematic animations (3DKA) of the tests. The 3DKA allow qualitative assessment of parameters related to posture and their possible effect on injury outcome. The orientation of the struck scapula and the lateral leaning of the torso were identified as potentially significant parameters. The ranges of variation in these parameters were quantified and compared to the number of rib fractures for each subject: the data suggested a correlation, but there was insufficient data for a probabilistic analysis. The 3DKA were published with this study and are freely available.