Accurate Estimation Of Postmortem Interval Research Articles

Cesedin Ayrışma Durumuna Göre Birikmiş Gün Sıcaklıkları ile Postmortem İnterval Tahmini

Postmortem interval dünyada modern adli bilim uygulamalarında çok önemli yere sahip araştırma konularından birisi olarak karşımıza çıkmaktadır. Postmortem intervalin belirlenmesinde morfolojik, biyokimyasal, adli patolojik, flowsitometrik, mikrobiyolojik, entomolojik, antropolojik, spektroskopik ve ana postmortem değişimler gibi çok sayıda yöntem kullanılmasına karşın tek bir test ya da yöntem ile kesinlik içeren sonuçların verilebilmesi mümkün görülmemektedir. Çünkü, kullanılan parametreleri etkileyen birçok fiziksel, kimyasal ve biyolojik süreç bulunmaktadır. Bu nedenle, postmortem interval hesaplanmasında mümkün olduğunca yeni yönteme ve kullanılagelen yöntemlerin geliştirilmesine ihtiyaç duyulmaktadır. Bu noktada, postmortem interval tahmininde kullanılan tafonomik yöntemlerin de geliştirilmesi, uygulamalı çalışmalarla bölgesel faktörler ve iklim etkisinin ortaya konması gerekmektedir. Özellikle, postmortem sürece etki eden bölgesel faktörlerin belirlenmesi ile ölüm sonrası geçen sürenin tahmininde daha kesin sonuçlara ulaşılabileceği kanaatindeyiz. Bu makalede, cesedin ayrışma durumuna göre birikmiş gün sıcaklıkları ile postmortem interval arasındaki ilişkinin değerlendirilmesi amaçlanmıştır. Anahtar Kelimeler: Adli Tafonomi; Postmortem Interval; Adli Antropoloji

Estimation of post-mortem interval: A comparison between cerebrospinal fluid and vitreous humour chemistry

Accurate estimation of post-mortem interval is of great importance in medico-legal autopsy cases. The present study is intended to compare the accuracy of estimating post-mortem interval from biochemical parameters of vitreous humour and cerebrospinal fluid (CSF). Both the fluids were collected from 100 medico-legal autopsies with known time of death and analysed for potassium, glucose, sodium, calcium, urea and creatinine. The current study found that vitreous humour is a better fluid in comparison to CSF for estimation of post-mortem interval. It is also observed that among the statistically significant parameters in both the fluids, level of potassium and sodium in vitreous humour are giving more accurate results in comparison to their corresponding parameters in CSF while accuracy of glucose is more or less same in both the fluid. Nevertheless potassium concentration in vitreous humour is a single best time honoured parameter to estimate post-mortem interval.

Applicability of partial characterization of cytochrome oxidase I in identification of forensically important flies (Diptera) from China and Egypt

Precise species identification of every insect sample collected from criminal scenes play an essential role in the accurate estimation of postmortem interval. The morphological similarity poses a great challenge for forensic entomologists. DNA-based method can be used as a supplemental means of morphological method. In the present study, we demonstrate the applicability of the 304-bp cytochrome oxidase I gene fragment in molecular identification of forensically important Diptera. We analyzed 75 specimens belonging to 19 species of 3 families originating from China (Calliphoridae: Chrysomya megacephala, Chrysomya albiceps, Chrysomya rufifacies, Chrysomya nigripes, Aldrichina grahami; Lucilia bazini, Lucilia caesar, Lucilia cuprina, Lucilia sericata, Lucilia porphyrina; Muscidae: Musca autumnalis, Musca domestica, Fannia canicularis, Stomoxys calcitrans; Sarcophagidae: Sarcophaga albiceps, Sarcophaga dux, Helicophagella melanura) and Egypt (Calliphoridae: C. megacephala, C. albiceps, L. sericata; Muscidae: M. domestica, F. canicularis, S. calcitrans, Synthesiomyia nudiseta; Sarcophagidae: Sarcophaga argyrostoma). This region was amplified using polymerase chain reaction followed by direct sequencing of the amplification products. Nucleotide sequence divergences were calculated using the Kimura two-parameter distance model and a neighbor-joining phylogenetic tree generated. Intraspecific variation ranged from 0-0.8 % and interspecific variation occurred between 1-19 %. Although all examined specimens were assigned to the correct species and formed distinct monophyletic clades, the data of the phylogenetic analysis were not completely in accordance with the traditional morphological classification. As both C. nigripes and A. grahami unexpectedly joined with Muscidae and Sarcophagidae groups respectively. Moreover, both Calliphorinae and Luciliinae clades failed to represent Calliphoridae as a separate group. Therefore, although molecular methods are beneficial especially if the available evidence are immature stage or degraded fragments of insect, we suggest using this fragment only in addition to other identification methods.

The Influence of Penetrative Trauma on the Rate of Decomposition*†

An understanding of the factors affecting decomposition is important for the accurate estimation of postmortem interval. An experimental study on the influence of penetrating trauma on decomposition rate was carried out using the domestic pig, Sus scrofa. The results of this study were: (i) Diptera were preferentially attracted to and oviposited at natural orifices. Trauma sites were not preferentially selected for oviposition; (ii) no differences between trauma and non-trauma groups were found in time to skeletonization, weight loss (p = 0.906), total body score (p = 0.824), body temperature (p = 0.967), or changes in soil pH (p = 0.684); and (iii) the effect of investigator disturbance was significant when decomposition was measured as weight loss (p = 0.000). This study suggests that penetrating trauma of the type used in this study cannot be considered a major factor in the rate of decomposition and time to skeletonization of a gunshot trauma victim.

Correlative analysis on the relationship between PMI and DNA degradation of cell nucleus in human different tissues

To determining the postmortem interval (PMI) through quantitative analysis of the DNA degradation of cell nucleus in human brain and spleen by using image analysis technique (IAT). The brain and spleen tissues from 32 cadavers with known PMI were collected, subjected to cell smear every 1 h within the first 5-36 h after death, stained by Feulgen-Van's staining, Three indices reflecting DNA in brain cells (astrocytes) and splenic lymphocytes, including integral optical density (IOD), average optical density (AOD), average gray (AG) were measured by employing the mage analysis instrument. The results showed that IOD and AOD declined and AG increased with the prolongation of dead time within 5-36 h. A correlation between the PMI and gray parameters (IOD, AOD and AG) was identified and the corresponding regression equation was obtained. The parameters (IOD, AOD and AG) were proved to be effective quantitative indicators for accurate estimation of PMI within 5-36 h after death.