Theory, simulation and experimental results of the acoustic detection of magnetization changes in superparamagnetic iron oxide

<p>Abstract</p> <p>Background</p> <p>Magnetic Particle Imaging is a novel method for medical imaging. It can be used to measure the local concentration of a tracer material based on iron oxide nanoparticles. While the resulting images show the distribution of the tracer material in phantoms or anatomic structures of subjects under examination, no information about the tissue is being acquired. To expand Magnetic Particle Imaging into the detection of soft tissue properties, a new method is proposed, which detects acoustic emissions caused by magnetization changes in superparamagnetic iron oxide.</p> <p>Methods</p> <p>Starting from an introduction to the theory of acoustically detected Magnetic Particle Imaging, a comparison to magnetically detected Magnetic Particle Imaging is presented. Furthermore, an experimental setup for the detection of acoustic emissions is described, which consists of the necessary field generating components, i.e. coils and permanent magnets, as well as a calibrated microphone to perform the detection.</p> <p>Results</p> <p>The estimated detection limit of acoustic Magnetic Particle Imaging is comparable to the detection limit of magnetic resonance imaging for iron oxide nanoparticles, whereas both are inferior to the theoretical detection limit for magnetically detected Magnetic Particle Imaging. Sufficient data was acquired to perform a comparison to the simulated data. The experimental results are in agreement with the simulations. The remaining differences can be well explained.</p> <p>Conclusions</p> <p>It was possible to demonstrate the detection of acoustic emissions of magnetic tracer materials in Magnetic Particle Imaging. The processing of acoustic emission in addition to the tracer distribution acquired by magnetic detection might allow for the extraction of mechanical tissue parameters. Such parameters, like for example the velocity of sound and the attenuation caused by the tissue, might also be used to support and improve ultrasound imaging. However, the method can also be used to perform imaging on its own.</p

Increasing phylogenetic stochasticity at high elevations on summits across a remote North American wilderness

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/1/ajb21328-sup-0002-AppendixS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/2/ajb21328-sup-0003-AppendixS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/3/ajb21328-sup-0004-AppendixS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/4/ajb21328.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/5/ajb21328-sup-0009-AppendixS9.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/6/ajb21328-sup-0005-AppendixS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/7/ajb21328-sup-0007-AppendixS7.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/8/ajb21328-sup-0006-AppendixS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/9/ajb21328-sup-0008-AppendixS8.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/10/ajb21328_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150529/11/ajb21328-sup-0001-AppendixS1.pd

A path forward in the debate over health impacts of endocrine disrupting chemicals

Several recent publications reflect debate on the issue of “endocrine disrupting chemicals” (EDCs), indicating that two seemingly mutually exclusive perspectives are being articulated separately and independently. Considering this, a group of scientists with expertise in basic science, medicine and risk assessment reviewed the various aspects of the debate to identify the most significant areas of dispute and to propose a path forward. We identified four areas of debate. The first is about the definitions for terms such as “endocrine disrupting chemical”, “adverse effects”, and “endocrine system”. The second is focused on elements of hormone action including “potency”, “endpoints”, “timing”, “dose” and “thresholds”. The third addresses the information needed to establish sufficient evidence of harm. Finally, the fourth focuses on the need to develop and the characteristics of transparent, systematic methods to review the EDC literature. Herein we identify areas of general consensus and propose resolutions for these four areas that would allow the field to move beyond the current and, in our opinion, ineffective debate

An Effective Assessment of Simvastatin-Induced Toxicity with NMR-Based Metabonomics Approach

BACKGROUND: Simvastatin, which is used to control elevated cholesterol levels, is one of the most widely prescribed drugs. However, a daily excessive dose can induce drug-toxicity, especially in muscle and liver. Current markers for toxicity reflect mostly the late stages of tissue damage; thus, more efficient methods of toxicity evaluation are desired. METHODOLOGY/PRINCIPAL FINDINGS: As a new way to evaluate toxicity, we performed NMR-based metabonomics analysis of urine samples. Compared to conventional markers, such as AST, ALT, and CK, the urine metabolic profile provided clearer distinction between the pre- and post-treatment groups treated with toxic levels of simvastatin. Through multivariate statistical analysis, we identified marker metabolites associated with the toxicity. Importantly, we observed that the treatment group could be further categorized into two subgroups based on the NMR profiles: weak toxicity (WT) and high toxicity (HT). The distinction between these two groups was confirmed by the enzyme values and histopathological exams. Time-dependent studies showed that the toxicity at 10 days could be reliably predicted from the metabolic profiles at 6 days. CONCLUSIONS/SIGNIFICANCE: This metabonomics approach may provide a non-invasive and effective way to evaluate the simvastatin-induced toxicity in a manner that can complement current measures. The approach is expected to find broader application in other drug-induced toxicity assessments

The regulatory challenge of chemicals in the environment: Toxicity testing, risk assessment, and decision-making models.

Environmental assessment for chemicals relies on models of fate, exposure, toxicity, risk, and impacts. Together, these models should provide scientific support for regulatory risk management decision-making, assuming that progress through the data-information-knowledge-wisdom (DIKW) hierarchy is both appropriate and sufficient. Improving existing regulatory processes necessitates continuing enhancement of interpretation and evaluation of key data for use in decision-making schemes, including ecotoxicity testing data, physical-chemical properties, and environmental fate processes. Yet, as environmental objectives also increase in scope and sophistication to encompass a safe chemical economy, testing, risk assessment, and decision-making are subject to additional complexity due to the ongoing interaction between science and policy models. Problems associated with existing design and implementation choices in science and policy have both limited needed development beyond chemo-centric environmental risk assessment modeling and constrained needed improvements in environmental decision-making. Without a thorough understanding of either the scientific foundations or the disparate evaluation processes for validation, quality, and relevance, this results in complex technical and philosophical problems that increase costs and decrease productivity. Both over- and under-management of chemicals are consequences of failure to validate key model assumptions, unjustified standardized views on data selection, and inordinate reification (i.e., abstract concepts are wrongly treated as facts)