Plasma phosphorylated-tau181 as a predictive biomarker for Alzheimer’s amyloid, tau and FDG PET status

Plasma phosphorylated-tau181 (p-tau181) showed the potential for Alzheimer’s diagnosis and prognosis, but its role in detecting cerebral pathologies is unclear. We aimed to evaluate whether it could serve as a marker for Alzheimer’s pathology in the brain. A total of 1189 participants with plasma p-tau181 and PET data of amyloid, tau or FDG PET were included from ADNI. Cross-sectional relationships of plasma p-tau181 with PET biomarkers were tested. Longitudinally, we further investigated whether different p-tau181 levels at baseline predicted different progression of Alzheimer’s pathological changes in the brain. We found plasma p-tau181 significantly correlated with brain amyloid (Spearman ρ = 0.45, P 18.85 pg/ml) at baseline had a higher risk of pathological progression in brain amyloid (HR: 2.32, 95%CI 1.32–4.08) and FDG PET (3.21, 95%CI 2.06–5.01) status. Plasma p-tau181 may be a sensitive screening test for detecting brain pathologies, and serve as a predictive biomarker for Alzheimer’s pathophysiology

The use of small Bloodstains in Blood Source Area of Origin Determinations

Due to the increased likelihood of manual measurement error, small bloodstains (≤ 3.0mm long) have rarely been used in three-dimensional blood source area of origin determinations. The advent of computer assisted measurement methods, offering improved levels of accuracy and precision, broadens the range of bloodstain sizes available for selection to determine a blood source area of origin. With inertia, viscosity and surface tension playing important, yet competing, roles in bloodstain formation, the power law relationships that exist between droplet volumes, droplet diameter, and bloodstain width suggest possible non-agreement between experimentally calculated angle of impact values when compared against those values theoretically expected. In order to compare experimental angle of impact calculation trends with angle of impact calculation theory, this preliminary study examines small bloodstains created by blood drops falling vertically onto surfaces offset from the vertical and small bloodstains generated by impact events subsequently deposited on adjacent vertical surfaces. This study shows that an apparent power law relationship may exist between the size of a parent blood droplet and the role of viscous and surface tension forces on subsequent bloodstain formation, particularly on those bloodstains caused by small droplets impacting obliquely with planar surfaces

The Polygenic Risk Score Knowledge Base offers a centralized online repository for calculating and contextualizing polygenic risk scores

The process of identifying suitable genome-wide association (GWA) studies and formatting the data to calculate multiple polygenic risk scores on a single genome can be laborious. Here, we present a centralized polygenic risk score calculator currently containing over 250,000 genetic variant associations from the NHGRI-EBI GWAS Catalog for users to easily calculate sample-specific polygenic risk scores with comparable results to other available tools. Polygenic risk scores are calculated either online through the Polygenic Risk Score Knowledge Base (PRSKB; https://prs.byu.edu ) or via a command-line interface. We report study-specific polygenic risk scores across the UK Biobank, 1000 Genomes, and the Alzheimer's Disease Neuroimaging Initiative (ADNI), contextualize computed scores, and identify potentially confounding genetic risk factors in ADNI. We introduce a streamlined analysis tool and web interface to calculate and contextualize polygenic risk scores across various studies, which we anticipate will facilitate a wider adaptation of polygenic risk scores in future disease research