Microbiome-based body site of origin classification of forensically relevant blood traces.

Human blood traces are amongst the most commonly encountered biological stains collected at crime scenes. Identifying the body site of origin of a forensic blood trace can provide crucial information in many cases, such as in sexual and violent assaults. However, means for reliably and accurately identifying from which body site a forensic blood trace originated are missing, but would be highly valuable in crime scene investigations. With this study, we introduce a taxonomy-independent deep neural network approach based on massively parallel microbiome sequencing, which delivers accurate body site of origin classification of forensically-relevant blood samples, such as menstrual, nasal, fingerprick, and venous blood. A total of 50 deep neural networks were trained using a large 16S rRNA gene sequencing dataset from 773 reference samples, including 220 female urogenital tract, 190 nasal cavity, 213 skin, and 150 venous blood samples. Validation was performed with de-novo generated 16S rRNA gene massively parallel sequencing (MPS) data from 94 blood test samples of four different body sites, and achieved high classification accuracy with AUC values at 0.992 for menstrual blood (N = 23), 0.978 for nasal blood (N = 16), 0.978 for fingerprick blood (N = 30), and 0.990 for venous blood (N = 25). The obtained highly accurate classification of menstrual blood was independent of the day of the menses, as established in additional 86 menstrual blood test samples. Accurate body site of origin classification was also revealed for 45 fresh and aged mock casework blood samples from all four body sites. Our novel microbiome approach works based on the assumption that a sample is from blood, as can be obtained in forensic practise from prior presumptive blood testing, and provides accurate information on the specific body source of blood, with high potentials for future forensic applications.

Arterial Blood Supply of the Nose: An Angiographic Study.

OBJECTIVE: To define anatomical variations associated with arterial blood supply of the nose which has clinical implications on the management of different disorders, especially intractable posterior epistaxis. STUDY DESIGN: Case series. METHODS: Selective angiography of external and internal carotid arteries of 100 patients scheduled for routine angiography was done. RESULTS: Different anatomical variations were documented. The ophthalmic artery can arise from the middle meningeal artery in 1% while ethmoidal arteries can be absent in 5%. The maxillary artery courses as 2 loops in the pterygopalatine fossa in 64% of cases where the descending palatine artery originates before the first loop or on its top so that caution is needed in controlling epistaxis. The sphenopalatine artery has different patterns of branching and may have more than 2 branches in 18% of cases. In 19% of cases, there is cross-circulation between both sides through the nasal blood supply. CONCLUSION: Angiographic study of the nose is a very helpful tool for accurate knowledge of anatomical variations of the arteries with a tremendous effect on our surgical approaches and techniques for the management of different diseases in the nasal region, especially intractable posterior epistaxis.