Background— Inflammation within atherosclerotic lesions contributes to plaque instability and vulnerability to rupture. We set out to evaluate the use of a macrophage labeling agent to identify carotid plaque inflammation by in vivo magnetic resonance imaging (MRI). Methods and Results— Thirty patients with symptomatic severe carotid stenosis scheduled for carotid endarterectomy underwent multi-sequence MRI of the carotid bifurcation before and after injection of ultrasmall superparamagnetic particles of iron oxide (USPIOs). USPIO particles accumulated in macrophages in 24 of 30 plaques (80%). Areas of signal intensity reduction, corresponding to USPIO/macrophage-positive histological sections, were visualized in 24 of 27 (89%) patients, with an average reduction in signal intensity induced by the USPIO particles of 24% (range, 3.1% to 60.8%). Conclusions— USPIO-enhanced MRI can identify plaque inflammation in vivo by accumulation of USPIO within macrophages in carotid plaques.

The development of novel nanomaterials with unique physico-chemical properties is increasing at a rapid rate, with potential applications across a broad range of manufacturing industries and consumer products. Nanomaterial safety is therefore becoming an increasingly contentious issue that has intensified over the past 4 years, and in response, a steady stream of studies focusing on nanotoxicology are emerging. However, it is becoming increasingly evident that nanomaterials cannot be treated in the same manner as chemical compounds with regards to their safety assessment, as their unique physico-chemical properties are also responsible for unexpected interactions with experimental components that generate misleading data-sets. In this report, we focus on nanomaterial interactions with colorimetric and fluorometric dyes, components of cell culture growth medium and genotoxicity assay components, and the resultant consequences on test systems are demonstrated. Thus, highlighting some of the potential confounding factors that need to be considered in order to ensure that in vitro genotoxicity assays report true biological impacts in response to nanomaterial exposure.

Plant-driven fungal weathering is a major pathway of soil formation, yet the precise mechanism by which mycorrhiza alter minerals is poorly understood. Here we report the first direct in situ observations of the effects of a soil fungus on the surface of a mineral over which it grew in a controlled experiment. An ectomycorrhizal fungus was grown in symbiosis with a tree seedling so that individual hyphae expanded across the surface of a biotite flake over a period of three months. Ultramicroscopic and spectroscopic analysis of the fungus-biotite interfaces revealed intimate fungal-mineral attachment, biomechanical forcing, altered interlayer spacings, substantial depletion of potassium (similar to 50 nm depth), oxidation of the biotite Fe(II), and the formation of vermiculite and clusters of Fe(III) oxides. Our study demonstrates the biomechanical-chemical alteration interplay at the fungus-biotite interface at the nanometer scale. Specifically, the weathering process is initiated by physical distortion of the lattice structure of biotite within 1 mu m of the attached fungal hypha. Only subsequently does the distorted volume become chemically altered through dissolution and oxidation reactions that lead to mineral neoformatioinfo:eu-repo/semantics/publishe