Predictable weathering of puparial hydrocarbons of necrophagous flies for determining the postmortem interval: a field experiment using Chrysomya rufifacies

Preadult development of necrophagous flies is commonly recognized as an accurate method for estimating the minimum postmortem interval (PMImin). However, once the PMImin exceeds the duration of preadult development, the method is less accurate. Recently, fly puparial hydrocarbons were found to significantly change with weathering time in the field, indicating their potential use for PMImin estimates. However, additional studies are required to demonstrate how the weathering varies among species. In this study, the puparia of Chrysomya rufifacies were placed in the field to experience natural weathering to characterize hydrocarbon composition change over time. We found that weathering of the puparial hydrocarbons was regular and highly predictable in the field. For most of the hydrocarbons, the abundance decreased significantly and could be modeled using a modified exponent function. In addition, the weathering rate was significantly correlated with the hydrocarbon classes. The weathering rate of 2-methyl alkanes was significantly lower than that of alkenes and internal methyl alkanes, and alkenes were higher than the other two classes. For mono-methyl alkanes, the rate was significantly and positively associated with carbon chain length and branch position. These results indicate that puparial hydrocarbon weathering is highly predictable and can be used for estimating long-term PMImin.

     

Effect of age and storage conditions on the volatile organic compound profile of blood

Cadaver-detection dogs are used by the police to locate missing persons, victims of homicide, and human remains following mass disasters. Training is conducted using a variety of training aids including blood which can be hours, weeks or months old and stored under variable conditions. The aim of this study was to chemically profile human blood using solid-phase microextraction coupled with gas chromatography–mass spectrometry to determine how the volatile organic compound (VOC) profile changed over time and under variable storage conditions. The VOC profiles of fresh and degraded blood were analyzed as well as blood stored at room temperature, refrigerated, and frozen. Fresh and degraded blood samples produced distinctive VOC patterns with VOC profiles becoming more complex over time. Freezing the blood produced a complex VOC profile that was clearly discriminated from the VOC profile for blood stored at room temperature or in a refrigerator. This study highlights the importance of standardizing the age and storage conditions when using blood as a training aid to ensure cadaver-detection dogs are exposed to an accurate representation of the blood VOCs they may encounter at a scene.     

挥发性有机化合物检测在食管-胃肠恶性肿瘤筛查中的研究进展

挥发性有机化合物(volatile organic compounds, VOCs)作为人类呼出气体中存在的物质,已广泛应用于癌症呼气标志物的研究。VOCs检测具有无创、操作便捷、特异性强等优势,在食管癌、胃癌、结直肠癌等消化道肿瘤早期筛查中有广泛应用前景。本文就VOCs在食管及胃肠恶性肿瘤筛查中的研究进展进行综述,为临床早期发现、早期诊断食管及胃肠恶性肿瘤提供参考。     

Volatile organic compounds in variably aged carrion impacted by the presence of the primary colonizer,Cochliomyia macellaria (Diptera: Calliphoridae)

International Journal of Legal Medicine - The attraction and colonization of vertebrate remains by carrion-associated arthropods are processes largely governed by olfaction. As remains decompose,...     

Identification of volatile organic compounds in muscle tissues of different species based on Headspace-Gas-Chromatography Ion-Mobility spectrometry

Species identification of unknown biological samples is crucial for forensic applications, especially in cases of explosion, disaster accidents, and body mutilation after murdering, as well as poaching, illegal trade in endangered animals, and meat food fraud. In this study, we identified 60 volatile organic compounds (VOCs) in fresh skeletal muscle tissues of seven different animal species (cattle, sheep, pigs, rabbits, rats, chickens and carp) and a human dead body by headspace-gas-chromatography ion-mobility spectrometry (HS-GC-IMS), and compared their differences by retention time, drift time and molecular weight. The results showed that these VOCs formed different gallery plot fingerprints in the skeletal muscle tissues of the human dead body and seven animal species. Principal component analysis (PCA) showed significantly different fingerprints between these species, and these fingerprints maintained good stability between the species and within the same species. Some VOCs have high species specificity, while VOCs of human fresh muscle tissues from different individual sources have little difference, demonstrating that all tested muscle tissue samples could be distinguished based on different VOCs. HS-GC-IMS has proved to be a rapid, high-throughput, highly sensitive and specific species identification method, which can be used for forensic species identification in criminal cases and disaster accidents, as well as detection in the field of food safety, such as meat fraud and adulteration.     

Histomorphometric estimation of age in paraffin-embedded ribs: a feasibility study

Estimation of age at death from human bones in legal medicine or in anthropology and archaeology is hampered by controversial results from the various macroscopic and histological techniques. This study attempted an estimation of age at death by histomorphometric analysis, from the fourth left rib adjacent to the costochondral joint in 80 forensic cases. Use of the picrosirius dye provided a reliable staining of the decalcified paraffin-embedded ribs. The total bone cortical area, the major and minor diameter as well as the area of the Haversian canals, the osteon areas of intact and remodelled secondary osteons, the area of non-Haversian canals were evaluated by means of image analysis, and derived parameters were calculated on both the internal and external sides of the rib. Most of the variables exhibited consistency between three different observers. Noteworthy, morphometric measurements in the internal cortex of the rib showed less variability than in the external cortex. Finally, discriminant statistical analysis from the 80 cases in this study indicated that the osteon population density was virtually sufficient to significantly discriminate between three groups of age: 20-39 (adulthood), 40-59 (middle age) and a group superior to 60. A subsequent blind evaluation of ten new subjects satisfactorily classified seven subjects out of ten within the three age groups. These results make feasible a larger study aimed at characterization of the practical relationships between bone tissue histomorphometry in ribs and chronological age in forensic cases.     

Childhood predictors of military fitness: a prospective, community-based, follow-up study from age 8 to age 18

Knowledge of the impact of childhood psychosocial problems on success in military service is scarce. The purpose of the study was to assess whether childhood psychosocial problems are associated with suitability for military service. The subjects were 2,622 Finnish boys born in 1981. They were first assessed with the Rutter parent and teacher questionnaires and self-reports (Children's Depression Inventory) at age 8. Their suitability for military service was assessed at age 18. A wide range of childhood problems, especially internalizing disorders, predicted release from military service. All informants had predictive association with later suitability for military service. The majority of children with psychiatric problems were later estimated to be fit for military service. The results show a predictive association between childhood psychiatric problems and early adult psychosocial impairment, as estimated by the ability to serve in the military forces.     

The use of proteomics to study wound healing: a preliminary study for forensic estimation of wound age

Proteomics is the analysis of the protein complement of the genome. The technique involves extracting proteins from the tissue being examined; separating the proteins using methods such as two-dimensional gel electrophoresis and then identifying the proteins by mass spectrometry. This paper describes the application of proteomics to incised wounds of the rat to determine if this technology could be applied to the important forensic issue of determining the age of wounds. Experimental incised skin wounds were inflicted on rats 5, 15, 30 and 60 minutes, 3, 6, 12 and 24 hours and 2, 5, 7 and 12 days before euthanasia. Each wound was excised and frozen at 80 degrees C; protein extracts were prepared and subjected to two-dimensional polyacrylamide gel electrophoresis over the range pH 3 to pH 10. Protein spots were identified using Matrix-assisted Laser Desorption/Ionisation Time-of-Flight (MALDI-TOF) mass spectrometry. A number of proteins were identified in skin wounds. After wounding the most prominent change was in the level of haemoglobin, which was elevated in wounds five minutes old and remained elevated for three hours, falling to near control levels after 12 hours. This pilot study has illustrated the feasibility for proteomics to be applied to determining wound age.     

Femoral shaft bowing with age: a digital radiological study of Anatolian Caucasian adults

PURPOSE: To determine the dimensions of the femoral shaft and their relationship to age in Anatolian Caucasian men and women. MATERIALS AND METHODS: Maximum femoral length (MFL), mid-shaft transverse diameter (MTD), and anterior bowing (AB) were studied in a sample of 104 adults. The linear dimensions and AB of the femoral shafts were measured on digital images. RESULTS: In males, mean MFL, MTD, and AB were 448.2 mm, 26.5 mm, and 759.3 mm, respectively. In females these measurements were 419.0 mm, 25.6 mm, and 779.5 mm. Males had longer MFL (P < 0.0001) and there was no difference between males and females regarding the other parameters. MFL and age were correlated in females (r = -0.374, P < 0.005), whereas they were not correlated in males. In females, MFL decreased until about 45 years of age and stabilized thereafter. MTD was correlated with age in males (r = 0.428, P < 0.002), increasing from adolescence to maturity. This correlation was insignificant in females and there was only a slight increase in diameter after about 30 years of age. AB and age were significantly correlated in females (r = -0.401, P < 0.003), with AB continuously increasing with age. The correlation between AB and age was insignificant in males. CONCLUSION: The increase in bone cross-sectional area in aging males may contribute to the maintenance of adequate mechanical competence throughout adulthood. In females this compensatory mechanism appears to be much less efficient and, accordingly, the end result of this process is AB of the femur and inevitable shortening of the bone.     

Epigenetic age signatures in the forensically relevant body fluid of semen: a preliminary study

To date, DNA methylation has been regarded as the most promising age-predictive biomarker. In support of this, several researchers have reported age predictive models based on the use of blood or even across a broad spectrum of tissues. However, there have been no publications that report epigenetic age signatures from semen, one of the most forensically relevant body fluids. In genome-wide DNA methylation profiles of 36 body fluids including blood, saliva, and semen, the previous age predictive models showed considerable prediction accuracy in blood and saliva but not in semen. Therefore, we selected CpG sites, whose methylation levels are strongly correlated with age in 12 semen profiles obtained from individuals of different ages, and investigated DNA methylation changes at these CpGs in 68 additional semen samples obtained from individuals aged 20 to 73 years using methylation SNaPshot reaction. Among the selected age-related CpG candidates, outstanding age correlation was obtained at cg06304190 in the TTC7B gene. Interestingly, the region around the TTC7B gene has been reported to show age-related DNA methylation alteration in the sperm methylome of 2 samples collected from individuals at certain time intervals. The age-predictive linear regression model trained with 3 CpGs (cg06304190 in the TTC7B gene, cg06979108 in the NOX4 gene and cg12837463) showed a high correlation between the predicted age and the chronological age, with an average absolute difference of approximately 5 years. These selected epigenetic age signatures are expected to be useful for considerably accurate age estimation in the forensically relevant body fluid of semen. However, because the findings were limited by small sample size, it will be necessary to further evaluate the age correlation of the selected CpGs and to encourage further investigation.     

Determination of age from pubic symphysis: an autopsy study

The present study was conducted on three hundred and thirty-six cases brought for autopsy to the Department of Forensic Medicine, Government Medical College, Amritsar, Punjab, India, during the period 2000-2002. Pubic bones of either sex were analysed according to Todd's method (1920; 1921a,b,c) as modified by McKern and Stewart (1957) to assess and compare the known age of the corpses. Cases belonged to both sexes, i.e. 79.46% males and 20.54% females. All the cases were above the age of 17 years. No difference was noted in the scoring of right and left pubic bones. The age estimation from different components in males and females up to the total score of 10 (23-28 years) was +/- 6, whereas above a score of 10 the estimated age was +/- 12 in males and +/- 9 in females. The age range given for scores of 14 and 15, which were 29+ and 36+ respectively, did not account for variability of age after 40 years. Therefore, the age assessment from pubic bones in the fourth decade age group and beyond is not reliable which is in variance to the study by McKern and Stewart (1957).     

The thickness of the renal parenchyma decreases with age: a CT study of 360 patients

Renal parenchymal thickness was estimated by using CT in 360 patients with no evidence of renal disease. In each patient, the measurements were normalized to the transverse diameter of the vertebral body and a reference table was formulated. The renal parenchymal thickness decreases about 10% per decade of increasing age in both men and women. These findings are consistent with previously reported findings based on autopsy material. The proposed table may be useful as a criterion for assessing normal renal parenchyma on CT.