Collagen degradation as a possibility to determine the post-mortem interval (PMI) of animal bones: a validation study referring to an original study of Boaks et al. (2014).

Estimation of the post-mortem interval (PMI) of unknown skeletal remains is a common forensic task. Boaks and colleagues demonstrated a new method for PMI estimation in showing a reduction of the collagen to non-collagen content (Co/NCo ratio) in porcine bones after a PMI of 12 months using the Sirius Red/Fast Green Collagen Staining Kit from Chondrex in 2014 (Boaks et al. Forensic Sci Int 240: 104-110, 2014). The aim of our study was to reproduce this method and to investigate if the method could be used for forensic issues. Sixteen fresh porcine bones were placed in prepared boxes where they were treated regularly with distilled water or with water from hay infusions. For determining the Co/NCo ratio, we used the Sirius Red/Fast Green Collagen Staining Kit from Chondrex, which stains collagenous (Co) proteins red and non-collagenous (NCo) proteins green Chondrex Inc. (2008). After a PMI of 1-3 months, an analysis of porcine bone thin sections was performed on the one hand with spectrophotometry, on the other hand with stereomicroscopy. Using spectrophotometry, we go low and partially negative Co/NCo ratios which were up to 100-fold lower than the results we expected to get. The data we got by stereomicroscopy and calculating the Co/NCo ratio from extracting the red and green content with the software MATLAB and so calculating the Co/NCo ratio showed a correlation between PMI and the Co/NCo ratio in the porcine bone samples. Regular addition of distilled water or water from a hay infusion did not produce any significant differences so that an increased presence of microorganisms had obviously no influence on collagen degradation.

Correction to: Collagen degradation as a possibility to determine the post-mortem interval (PMI) of animal bones: a validation study referring to an original study of Boaks et al. (2014).

The original version of this article contains an error. The Author Katharina Hoeland incorrectly listed as Katharina Höland. The correct spelling is presented above. The original article has been corrected.

Cranial secular change from the nineteenth to the twentieth century in modern German individuals compared to modern Euro-American individuals.

Studying secular changes on human skulls is a central issue in anthropological research, which is however insufficiently investigated for modern German populations. With our study, we focus on morphological cranial variations within Germans during the nineteenth and twentieth centuries. To study this, we recorded different facial landmarks from a cohort study of about 540 German individuals of different age and sex by calculating their cranial size, shape dimensions, and cranial module and cranial capacity to get information about variations occurring during the decades. According to this, measured variables for Germans and Americans, to which we compared our results, were maximum cranial length (glabello-occipital length), basion-bregma height (BBH), basion-nasion length (BNL), maximum cranial breadth (XCB), and cranial base breadth (AUB). Cranial size was calculated as the geometric mean of GOL, BBH, and XCB. Samples were organized into quarter century birth cohorts, with birth years ranging from 1800 to 1950. One-way ANOVA was used to test for variation among cohorts. Over the past 150 years, Americans and Germans showed significant parallel changes, but the American cranium remained relatively higher, with a longer cranial base, as well as narrower than the German cranium. Our results should also lead to the extension of the range of populations listed and investigated for Fordisc®, a forensic software to identify unknown individuals as from their skeletal remains or just parts of them. Fordisc cannot provide a satisfying identification of European individuals yet because the database is missing enough European reference samples.

Collagen degradation as a possibility to determine the post-mortem interval (PMI) of human bones in a forensic context - A survey.

To find out the time since death (PMI) of a human individual, from which only skeletal remains are left is a difficult question to answer, since methods currently available don't bring concrete answers. Subsequent to our validation study on porcine bones, we focused on human bones analysing if collagen degradation would occur at a predictive rate so that the method may be used for PMI-estimation. We tried to reproduce a method for determining the Co/NCo (Collagen to Non-Collagen) ratio of porcine bones Boaks et al. demonstrated in 2014. Our study sample consisted of 37 human bones from a forensic PMI context and 11 archaeological samples; we prepared thin bone sections of 250 µm; after staining the sections we used spectrophotometry for a portion of the samples and stereomicroscopy and digital imaging to analyze the Co/NCo ratio. Detecting the Co/NCo ratio with spectrophotometry produced results much lower than those published by Boaks et al. (2014) on porcine bone samples and much lower than physiologically expected; a similar result we also got in our validation study on porcine bone samples. We, therefore, applied our new method of stereomicroscopy and digital imaging, which we previously tested on porcine bones. The samples of male individuals showed a significant reduction of the Co/NCo ratio correlating to the PMI. Nevertheless, we still consider analyzing the Co/NCo ration of human bone samples not sufficient for forensic issues. Therefore, greater reference data as well as more experience in practice are needed.