Subsegmentation of the Kidney in Experimental MR Images Using Morphology-Based Regions-of-Interest or Multiple-Layer Concentric Objects.

Functional renal MRI promises access to a wide range of physiologically relevant parameters such as blood oxygenation, perfusion, tissue microstructure, pH, and sodium concentration. For quantitative comparison of results, representative values must be extracted from the parametric maps obtained with these different MRI techniques. To improve reproducibility of results this should be done based on regions-of-interest (ROIs) that are clearly and objectively defined.Semiautomated subsegmentation of the kidney in magnetic resonance images represents a simple but very valuable approach for the quantitative analysis of imaging parameters in multiple ROIs that are associated with specific anatomic locations. Thereby, it facilitates comparing MR parameters between different kidney regions, as well as tracking changes over time.Here we provide detailed step-by-step instructions for two recently developed subsegmentation techniques that are suitable for kidneys of small rodents: i) the placement of ROIs in cortex, outer and the inner medulla based on typical kidney morphology and ii) the division of the kidney into concentrically oriented layers.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers

Expression of DC-SIGN and DC-SIGNR on human sinusoidal endothelium: a role for capturing hepatitis C virus particles.

Hepatic sinusoidal endothelial cells are unique among endothelial cells in their ability to internalize and process a diverse range of antigens. DC-SIGNR, a type 2 C-type lectin expressed on liver sinusoids, has been shown to bind with high affinity to hepatitis C virus (HCV) E2 glycoprotein. DC-SIGN is a closely related homologue reported to be expressed only on dendritic cells and a subset of macrophages and has similar binding affinity to HCV E2 glycoprotein. These receptors function as adhesion and antigen presentation molecules. We report distinct patterns of DC-SIGNR and DC-SIGN expression in human liver tissue and show for the first time that both C-type lectins are expressed on sinusoidal endothelial cells. We confirmed that these receptors are functional by demonstrating their ability to bind HCV E2 glycoproteins. Although these lectins on primary sinusoidal cells support HCV E2 binding, they are unable to support HCV entry. These data support a model where DC-SIGN and DC-SIGNR on sinusoidal endothelium provide a mechanism for high affinity binding of circulating HCV within the liver sinusoids allowing subsequent transfer of the virus to underlying hepatocytes, in a manner analogous to DC-SIGN presentation of human immunodeficiency virus on dendritic cells

The living space: Psychological well-being and mental health in response to interiors presented in virtual reality

There has been a recent interest in how architecture affects mental health and psychological well-being, motivated by the fact that we spend the majority of our waking time inside and interacting with built environments. Some studies have investigated the psychological responses to indoor design parameters; for instance, contours, and proposed that curved interiors, when compared to angular ones, were aesthetically preferred and induced higher positive emotions. The present study aimed to systematically examine this hypothesis and further explore the impact of contrasting contours on affect, behavior, and cognition. We exposed 42 participants to four well-matched indoor living rooms under a free-exploration photorealistic virtual reality paradigm. We included style as an explorative second-level variable. Out of the 33 outcome variables measured, and after correcting for false discoveries, only two eventually confirmed differences in the contours analysis, in favor of angular rooms. Analysis of style primarily validated the contrast of our stimulus set, and showed significance in one other dependent variable. Results of additional analysis using the Bayesian framework were in line with those of the frequentist approach. The present results provide evidence against the hypothesis that curvature is preferred, suggesting that the psychological response to contours in a close-to-reality architectural setting could be more complex. This study, therefore, helps to communicate a more complete scientific view on the experience of interior spaces and proposes directions for necessary future research

Evaluation of the radionuclide tracer test conducted at the project Gnome Underground Nuclear Test Site, New Mexico

A radionuclide tracer test was conducted in 1963 by the U.S. Geological Survey at the Project Gnome underground nuclear test site, approximately 40 km southeast of Carlsbad, New Mexico. The tracer study was carried out under the auspices of the U.S. Atomic Energy Commission (AEC) to study the transport behavior of radionuclides in fractured rock aquifers. The Culebra Dolomite was chosen for the test because it was considered to be a reasonable analogue of the fractured carbonate aquifer at the Nevada Test Site (NTS), the principal location of U.S. underground nuclear tests. Project Gnome was one of a small number of underground nuclear tests conducted by the AEC at sites distant from the NTS. The Gnome device was detonated on December 10, 1961 in an evaporate unit at a depth of 360 m below ground surface. Recently, the U.S. Department of Energy (DOE) implemented an environmental restoration program to characterize, remediate, and close these offsite nuclear test areas. An early step in this process is performance of a preliminary risk analysis of the hazard posed by each site. The Desert Research Institute has performed preliminary hydrologic risk evaluations for the groundwater transport pathway at Gnome. That evaluation included the radioactive tracer test as a possible source because the test introduced radionuclides directly into the Culebra Dolomite, which is the only aquifer at the site. This report presents a preliminary evaluation of the radionuclide tracer test as a source for radionuclide migration in the Culebra Dolomite. The results of this study will assist in planning site characterization activities and refining estimates of the radionuclide source for comprehensive models of groundwater transport st the Gnome site

Probing renal blood volume with magnetic resonance imaging

Damage to the kidney substantially reduces life expectancy. Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. In vivo assessment of renal haemodynamics and tissue oxygenation remains a challenge. Blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) is sensitive to changes in the effective transversal relaxation time (T(2)*) in vivo, is non-invasive and indicative of renal tissue oxygenation. However, the renal T(2)* to tissue pO(2) relationship is not governed exclusively by renal blood oxygenation, but is affected by physiological confounders with alterations in renal blood volume fraction (BVf) being of particular relevance. To decipher this interference probing renal BVf is essential for the pursuit of renal MR oximetry. Superparamagnetic iron oxide nanoparticle (USPIO) preparations can be used as MRI visible blood pool markers for detailing alterations in BVf. This review promotes the opportunities of MRI based assessment of renal BVf. Following an outline on the specifics of renal oxygenation and perfusion, changes in renal BVf upon interventions and their potential impact on renal T(2)* are discussed. We also describe the basic principles of renal BVf assessment using ferumoxytol enhanced MRI in the equilibrium concentration regime. We demonstrate that ferumoxytol does not alter control of renal haemodynamics and oxygenation. Preclinical applications of ferumoxytol enhanced renal MRI as well as considerations for its clinical implementation for examining renal BVf changes are provided alongside practical considerations. Finally, we explore the future directions of MRI based assessment of renal BVf

The Effect of Time and pH on Hemolysis During Cardiopulmonary Bypass

Articlehttp://deepblue.lib.umich.edu/bitstream/2027.42/96979/1/UMURF-Issue05_2008-ABansal.pd

Resolving discrepancies between hydraulic and chemical calibration data for seawater intrusion groundwater flow models by considering climate-driven sea level change.

Groundwater models of seawater intrusion environments can be calibrated using both hydraulic and chemical information. The possible impact of the long-term transient process of sea level change is difficult to identify, but important to accurate simulation of present conditions. The response times of the pressure and chemical fields to major fluctuations in sea level change are investigate

Three-dimensional mapping of equiprobable hydrostratigraphic units at the Frenchman Flat Corrective Action Unit, Nevada Test Site

Geological and geophysical data are used with the sequential indicator simulation algorithm of Gomez-Hernandez and Srivastava to produce multiple, equiprobable, three-dimensional maps of informal hydrostratigraphic units at the Frenchman Flat Corrective Action Unit, Nevada Test Site. The upper 50 percent of the Tertiary volcanic lithostratigraphic column comprises the study volume. Semivariograms are modeled from indicator-transformed geophysical tool signals. Each equiprobable study volume is subdivided into discrete classes using the ISIM3D implementation of the sequential indicator simulation algorithm. Hydraulic conductivity is assigned within each class using the sequential Gaussian simulation method of Deutsch and Journel. The resulting maps show the contiguity of high and low hydraulic conductivity regions

Near-field modeling in Frenchman Flat, Nevada Test Site

The US Department of Energy (DOE) is investigating the effects of nuclear testing in underground test areas (the UGTA program) at the Nevada Test Site. The principal focus of the UGTA program is to better understand and define subsurface radionuclide migration. The study described in this report focuses on the development of tools for generating maps of hydrogeologic characteristics of subsurface Tertiary volcanic units at the Frenchman Flat corrective Action Unit (CAU). The process includes three steps. The first step involves generation of three-dimensional maps of the geologic structure of subsurface volcanic units using geophysical logs to distinguish between two classes: densely welded tuff and nonwelded tuff. The second step generates three-dimensional maps of hydraulic conductivity utilizing the spatial distribution of the two geologic classes obtained in the first step. Each class is described by a correlation structure based on existing data on hydraulic conductivity, and conditioned on the generated spatial location of each class. The final step demonstrates the use of the maps of hydraulic conductivity for modeling groundwater flow and radionuclide transport in volcanic tuffs from an underground nuclear test at the Frenchman Flat CAU. The results indicate that the majority of groundwater flow through the volcanic section occurs through zones of densely welded tuff where connected fractures provide the transport pathway. Migration rates range between near zero to approximately four m/yr, with a mean rate of 0.68 m/yr. This report presents the results of work under the FY96 Near-Field Modeling task of the UGTA program

Detailing the relation between renal T(2)* and renal tissue pO2 using an integrated approach of parametric magnetic resonance imaging and invasive physiological measurements

OBJECTIVES: This study was designed to detail the relation between renal T2* and renal tissue pO2 using an integrated approach that combines parametric magnetic resonance imaging (MRI) and quantitative physiological measurements (MR-PHYSIOL. MATERIALS AND METHODS: Experiments were performed in 21 male Wistar rats. In vivo modulation of renal hemodynamics and oxygenation was achieved by brief periods of aortic occlusion, hypoxia, and hyperoxia. Renal perfusion pressure (RPP), renal blood flow (RBF), local cortical and medullary tissue pO2, and blood flux were simultaneously recorded together with T2*, T2 mapping, and magnetic resonance-based kidney size measurements (MR-PHYSIOL). Magnetic resonance imaging was carried out on a 9.4-T small-animal magnetic resonance system. Relative changes in the invasive quantitative parameters were correlated with relative changes in the parameters derived from MRI using Spearman analysis and Pearson analysis. RESULTS: Changes in T2* qualitatively reflected tissue pO2 changes induced by the interventions. T2* versus pO2 Spearman rank correlations were significant for all interventions, yet quantitative translation of T2*/pO2 correlations obtained for one intervention to another intervention proved not appropriate. The closest T2*/pO2 correlation was found for hypoxia and recovery. The interlayer comparison revealed closest T2*/pO2 correlations for the outer medulla and showed that extrapolation of results obtained for one renal layer to other renal layers must be made with due caution. For T2* to RBF relation, significant Spearman correlations were deduced for all renal layers and for all interventions. T2*/RBF correlations for the cortex and outer medulla were even superior to those between T2* and tissue pO2. The closest T2*/RBF correlation occurred during hypoxia and recovery. Close correlations were observed between T2* and kidney size during hypoxia and recovery and for occlusion and recovery. In both cases, kidney size correlated well with renal vascular conductance, as did renal vascular conductance with T2*. Our findings indicate that changes in T2* qualitatively mirror changes in renal tissue pO2 but are also associated with confounding factors including vascular volume fraction and tubular volume fraction. CONCLUSIONS: Our results demonstrate that MR-PHYSIOL is instrumental to detail the link between renal tissue pO2 and T2* in vivo. Unravelling the link between regional renal T2* and tissue pO2, including the role of the T2* confounding parameters vascular and tubular volume fraction and oxy-hemoglobin dissociation curve, requires further research. These explorations are essential before the quantitative capabilities of parametric MRI can be translated from experimental research to improved clinical understanding of hemodynamics/oxygenation in kidney disorders