Cartilage: A new parameter for the determination of the postmortem interval?

Postmortem chondrocyte viability in porcine articular cartilage: Influence of time, temperature, and burial under winter conditions

The aim of the present study was to investigate the effects of time, temperature, and burial in a natural environment on the viability of chondrocytes in porcine femoral condyles using confocal laser scanning microscopy. Hind trotters from 10 pigs were buried or left unburied. Samples were collected daily and stained with a combination of vital dyes (calcein-AM and ethidium homodimer-1). The chondrocytes showed an intense staining corresponding to their vitality. In the first 3 days, viability decreased slowly and showed no statistical difference between buried and unburied samples. After the first 3 days, it decreased rapidly, with the viability of the buried samples being 66% on day 4, decreasing to 25% on day 8 and to 16% on day 10, while in the unburied samples it decreased to 43% on day 4, 13% on day 8 and 5% on day 10. Our results indicate a time, temperature, and burial dependent decrease in chondrocyte viability and suggest the use of chondrocyte viability as a marker for estimating PMI in both the natural environment and in animals, as well as its potential use in humans.

The micro CT evaluation of crown and root pulp volume versus dentin thickness in teeth in postmortem interval (PMI)

Determining the postmortem interval (PMI) is one of the main study subjects of forensic sciences. The main purpose of this prospective in vitro study that was the Micro-CT evaluation of teeth crown and root pulp volume versus dentin thickness in terms of PMI determination. The study involved 60 female Wistar rats, with weights ranging from 270 to 320 g. These rats were grouped into six different post-mortem period categories. Following the animals' sacrifice, they were subjected to a natural putrefaction period, with a control group, in the grounds of a sheltered garden. Hemi-mandible samples were then extracted and placed in glass tubes for Micro-CT evaluations, following the progression of putrefaction processes. The pulp volume and dentin thickness were assessed using Micro-CT, and the gathered data underwent statistical analysis. Micro-CT was employed to analyze sixty right mandibular second molar teeth in the hemi-mandible. The crown pulp volume exhibited a reduction in group 6, with a value of 0.239 mm3 after a three-month period of natural putrefaction (p < 0.001). There is statistically differences among groups in case of pairwise comparison (p < 0.05). However, the root pulp volume and dentin thickness variables did not display any statistically significant changes. Despite certain limitations associated with this study, the Micro-CT findings concerning teeth pulp volume can serve as an objective parameter, especially for late postmortem investigations and the estimation of time of death.

Development of Megaselia scalaris at constant temperatures and its significance in estimating the time of death

Megaselia scalaris (Schmitz, 1938) (Diptera: Phoridae) is a common insect in forensic science that is frequently found in indoor cases, particularly on corpses in closed environments. Although this species is useful for estimating the minimum postmortem interval (PMImin) in the absence of Calliphoridae, there is a lack of data on its development in China. Herein, we studied the development of M. scalaris exposed to seven constant temperatures ranging from 16 to 34 °C. The mean (± SD) developmental durations of M. scalaris from egg to adult stage at 16, 19, 22, 25, 28, 31, and 34 °C were 1486.9 ± 75.3, 823.7 ± 42.8, 448.2 ± 59.8, 417.7 ± 19.7, 297.2 ± 27.3, 272.9 ± 10.4, and 253.0 ± 5.0 h, respectively. The mean (± SE) lower developmental threshold temperature (TL) and the thermal summation constant (K) were determined by a linear model as 12.69 ± 0.3 °C and 4965.8 ± 227.9-degree hours, respectively. A nonlinear model estimated the lower developmental threshold temperature, intrinsic optimum temperature, and upper lethal developmental threshold temperature as 14.58, 21.00, and 34.15 °C, respectively. We established three development models to estimate the age of the immature insect, namely the isomegalen diagram, isomorphen diagram, and thermal summation model. In addition, a regression analysis of the relationship between body length and total development time from hatching to pupariation was performed. Our findings provide a basis for applications of M. scalaris in PMImin estimations.

Attenuated total reflection-Fourier transform infrared spectroscopy: a universal analytical technique with promising applications in forensic analyses

Contemporary criminal investigations are based on the statements made by the victim and the eyewitnesses. They also rely on the physical evidences found in the crime scene. These evidences, and more particularly biological ones, have a great judicial value in the courtroom. They are usually used to revoke the suspect's allegations and confirm or refute the statements made by the victim and the witnesses. Stains of body fluids are biological evidences highly sought by forensic investigators. In many criminal cases, the success of the investigation relies on the correct identification and classification of these stains. Therefore, the adoption of reliable and accurate forensic analytical methods seems to be of vital importance to attain this objective. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) is a modern and universal analytical technique capable of fingerprint recognition of the analyte using minimal amount of the test sample. The current systematic review aims to through light on the fundamentals of this technique and to illustrate its wide range of applications in forensic investigations. ATR-FTIR is a nondestructive technique which has demonstrated an exceptional efficiency in detecting, identifying and discriminating between stains of various types of body fluids usually encountered in crime scenes. The ATR-FTIR spectral data generated from bloodstains can be used to deduce a wealth of information related to the donor species, age, gender, and race. These data can also be exploited to discriminate between stains of different types of bloods including menstrual and peripheral bloods. In addition, ATR-FTIR has a great utility in the postmortem investigations. More particularly, in estimating the postmortem interval and diagnosing death caused by extreme weather conditions. It is also useful in diagnosing some ambiguous death causes such as fatal anaphylactic shock and diabetic ketoacidosis.

Acute Cartilage Injury Induced by Trans-Articular Sutures

OBJECTIVE

To determine the extent of acute cartilage injury by using trans-articular sutures.

METHODS

Five different absorbable sutures, monofilament polydioxanone (PDS) and braided polyglactin (Vicryl), were compared on viable human osteochondral explants. An atraumatic needle with 30 cm of thread was advanced through the cartilage with the final thread left in the tissue. A representative 300 μm transversal slice from the cartilage midportion was stained with Live/Dead probes, scanned under the confocal laser microscope, and analyzed for the diameters of (a) central "Black zone" without any cells, representing in situ thread thickness and (b) "Green zone," including the closest Live cells, representing the maximum injury to the tissue. The exact diameters of suture needles and threads were separately measured under an optical microscope.

RESULTS

The diameters of the Black (from 144 to 219 µm) and the Green zones (from 282 to 487 µm) varied between the different sutures (P < 0.001). The Green/Black zone ratio remained relatively constant (from 1.9 to 2.2; P = 0.767). A positive correlation between thread diameters and PDS suturing material, toward the Black and Green zone, was established, but needle diameters did not reveal any influence on the zones.

CONCLUSIONS

The width of acute cartilage injury induced by the trans-articular sutures is about twice the thread thickness inside of the tissue. Less compressible monofilament PDS induced wider tissue injury in comparison to a softer braided Vicryl. Needle diameter did not correlate to the extent of acute cartilage injury.

Safranin O without fast green is the best staining method for testing the degradation of macromolecules in a cartilage extracellular matrix for the determination of the postmortem interval

Methods for the determination of the postmortem interval (PMI) include methods that monitor the postmortem changes of cells and molecules in different tissues. The rate of pathological degradation of macromolecules in the extracellular matrix (ECM) of hyaline cartilage could be verified by assessing the intensity of collagen and proteoglycan (PG) staining. In the presented in vitro pilot study, this methodology was used for the first time to determine PMI. The osteochondral samples of three donors were stored at 11 °C and 35 °C and analyzed on day 1, day 12, and day 36 postmortem. The intensity of staining using Masson's trichrome and Sirius red for collagen, and Alcian blue and Safranin O dyes for PG was estimated ten times according to the modified Bern grading scale. Statistical analysis showed that the Safranin O without Fast green method is the most appropriate (raters agreement 0.5541) for up to 36 days postmortem, and that the influence of time is more important (p = 0.023) than the influence of temperature (p = 0.061) on the degradation of the ECM macromolecules. The described method, which is simple and can be performed in any histological laboratory, should be verified in corpore conditions, on a large number of donors, and using an objective method for assessing the intensity of cartilage macromolecule staining for PMI determination.

An investigation on annular cartilage samples for post-mortem interval estimation using Fourier transform infrared spectroscopy

Many attempts have been made to estimate the post-mortem interval (PMI) using bioanalytical methods based on multiple biological samples. Cartilage tissues could be used as an alternative for this purpose because their rate of degradation is slower than that of other soft tissue or biofluid samples. In this study, we applied Fourier transform infrared (FTIR) spectroscopy to acquire bioinformation from human annular cartilages within 30 days post-mortem. Principal component analysis (PCA) showed that sex and causes of death have almost no impact on the overall spectral variations caused by post-mortem changes. With pre-processing approaches, several predicted models were established using a conventional machine learning method, known as the partial least square (PLS) regression. The best model achieved a satisfactory prediction with a low error of 1.49 days using the second derivative transform of 3-point smoothing and extended multiplicative scatter correction (EMSC), and the spectral regions from proteins and carbohydrates contributed greatly to the PMI prediction. This study demonstrates the feasibility of cartilage-based FTIR analysis for PMI estimation. Further work will introduce advanced algorithms for more accurate and precise PMI prediction.

DNA Barcoding in Forensic Entomology - Establishing a DNA Reference Library of Potentially Forensic Relevant Arthropod Species

Throughout the years, DNA barcoding has gained in importance in forensic entomology as it leads to fast and reliable species determination. High-quality results, however, can only be achieved with a comprehensive DNA barcode reference database at hand. In collaboration with the Bavarian State Criminal Police Office, we have initiated at the Bavarian State Collection of Zoology the establishment of a reference library containing arthropods of potential forensic relevance to be used for DNA barcoding applications. CO1-5P' DNA barcode sequences of hundreds of arthropods were obtained via DNA extraction, PCR and Sanger Sequencing, leading to the establishment of a database containing 502 high-quality sequences which provide coverage for 88 arthropod species. Furthermore, we demonstrate an application example of this library using it as a backbone to a high throughput sequencing analysis of arthropod bulk samples collected from human corpses, which enabled the identification of 31 different arthropod Barcode Index Numbers.

Research progress in the estimation of the postmortem interval by Chinese forensic scholars

The determination of time since death or the postmortem interval (PMI) is one of the most important and frequently asked questions in forensic medicine. Medicolegal scholars and forensic pathologists around the world have studied the estimation of PMI extensively in the past, and many novel methods and advanced technologies have now been applied in the field. For several centuries, Chinese forensic examiners have also worked on the estimation of the PMI, and there are a large number of excellent studies published in Chinese rather than in English, and these are not easily accessible or known internationally. Therefore we have conducted a review of relevant studies published by Chinese forensic scholars in the last few decades. The scope of this review is to provide a concise summary of the current progress in the estimation of PMI by Chinese forensic researchers using molecular biology, spectroscopic technology, entomological methods, energy changes, thanatochemistry and other methods.

Dielectric study of interaction of water with normal and osteoarthritis femoral condyle cartilage

The main goal of this paper is the in vitro study of healthy and osteoarthritis (OA) human cartilage using the dielectric spectroscopy in the alpha-dispersion region of the electric field and in the temperatures from 25 to 140°C. The activation energy of conductivity needed to break the bonds formed by water in the extracellular matrix takes the average values of 61kJ/mol and 44kJ/mol for the control and OA cartilages, respectively. At 28°C, the small difference appears in the permittivity decrement between the control and OA cartilages, while the conductivity increment is about 2 times higher for the control tissue than that for the OA tissue. At 75°C, the conductivity increment for both of these samples is 8 times higher than their respective permittivity decrement. In addition, at 140°C the values of these both parameters for the OA tissue decrease by 8 times as compared to those recorded for the control sample. The relaxation frequency of about 10kHz is similar for both of these samples. The knowledge on dielectric properties of healthy and OA cartilage may prove relevant to tissue engineering focused on the repair of cartilage lesions via the layered structure designing.

Postmortem degradation of skeletal muscle proteins: a novel approach to determine the time since death

Estimating the time since death is a very important aspect in forensic sciences which is pursued by a variety of methods. The most precise method to determine the postmortem interval (PMI) is the temperature method which is based on the decrease of the body core temperature from 37 °C. However, this method is only useful in the early postmortem phase (~0-36 h). The aim of the present work is to develop an accurate method for PMI determination beyond this present limit. For this purpose, we used sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting, and casein zymography to analyze the time course of degradation of selected proteins and calpain activity in porcine biceps femoris muscle until 240 h postmortem (hpm). Our results demonstrate that titin, nebulin, desmin, cardiac troponin T, and SERCA1 degraded in a regular and predictable fashion in all samples investigated. Similarly, both the native calpain 1 and calpain 2 bands disintegrate into two bands subsequently. This degradation behavior identifies muscular proteins and enzymes as promising substrates for future molecular-based PMI determination technologies.