Accurate simultaneous quantification of liver steatosis and iron overload in diffuse liver diseases with MRI

Purpose: To evaluate the diagnostic performances of 3 Tesla multi-echo chemical shift-encoded gradient echo magnetic resonance (MECSE-MR) imaging to simultaneously quantify liver steatosis and iron overload in a wide spectrum of diffuse liver diseases having biopsy as reference standard. Methods: MECSE-MR-acquired images were used to calculate fat fraction and iron content in a single breath-hold in 109 adult patients. Proton density fat fraction (PDFF) was prospectively estimated using complex-based data reconstruction with multipeak fat modeling. Water R2* was used to estimate iron content. Biopsy was obtained in all cases, grading liver steatosis, siderosis, inflammation, and fibrosis. Differences in PDFF and R2* values across histopathological grades were analyzed, and ROC curves analyses evaluated the MR diagnostic performance. Results: Calculated fat fraction measurements showed significant differences (p < 0.001) among steatosis grades, being unaffected by the presence of inflammation or fibrosis (p ≥ 0.05). A strong correlation was found between fat fraction and steatosis grade (R S = 0.718, p < 0.001). Iron deposits did not affect fat fraction quantitation (p ≥ 0.05), except in cases with severe iron overload (grade 4). A strong positive correlation was also observed between R2* measurements and iron grades (R S = 0.704, p < 0.001). Calculated R2* values were not different across grades of steatosis, inflammation, and fibrosis (p ≥ 0.05). Conclusion: A MECSE-MR sequence simultaneously quantifies liver steatosis and siderosis, regardless coexisting liver inflammation or fibrosis, with high accuracy in a wide spectrum of diffuse liver disorders. This sequence can be acquired within a single breath-hold and can be implemented in the routine MR evaluation of the liver.This work was partially funded by a research grant from the Teaching and Research Department of Centro Hospitalar do Porto (DEFI:309/12(213-DEFI/251-CES)) and from a Spanish Ministry of Health and Carlos III Health Institute funding grant (PI12/01262). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Anyonic interferometry and protected memories in atomic spin lattices

Strongly correlated quantum systems can exhibit exotic behavior called topological order which is characterized by non-local correlations that depend on the system topology. Such systems can exhibit remarkable phenomena such as quasi-particles with anyonic statistics and have been proposed as candidates for naturally fault-tolerant quantum computation. Despite these remarkable properties, anyons have never been observed in nature directly. Here we describe how to unambiguously detect and characterize such states in recently proposed spin lattice realizations using ultra-cold atoms or molecules trapped in an optical lattice. We propose an experimentally feasible technique to access non-local degrees of freedom by performing global operations on trapped spins mediated by an optical cavity mode. We show how to reliably read and write topologically protected quantum memory using an atomic or photonic qubit. Furthermore, our technique can be used to probe statistics and dynamics of anyonic excitations.Comment: 14 pages, 6 figure

Interaction Pattern of Arg 62 in the A-Pocket of Differentially Disease-Associated HLA-B27 Subtypes Suggests Distinct TCR Binding Modes

The single amino acid replacement Asp116His distinguishes the two subtypes HLA-B*2705 and HLA-B*2709 which are, respectively, associated and non-associated with Ankylosing Spondylitis, an autoimmune chronic inflammatory disease. The reason for this differential association is so far poorly understood and might be related to subtype-specific HLA:peptide conformations as well as to subtype/peptide-dependent dynamical properties on the nanoscale. Here, we combine functional experiments with extensive molecular dynamics simulations to investigate the molecular dynamics and function of the conserved Arg62 of the α1-helix for both B27 subtypes in complex with the self-peptides pVIPR (RRKWRRWHL) and TIS (RRLPIFSRL), and the viral peptides pLMP2 (RRRWRRLTV) and NPflu (SRYWAIRTR). Simulations of HLA:peptide systems suggest that peptide-stabilizing interactions of the Arg62 residue observed in crystal structures are metastable for both B27 subtypes under physiological conditions, rendering this arginine solvent-exposed and, probably, a key residue for TCR interaction more than peptide-binding. This view is supported by functional experiments with conservative (R62K) and non-conservative (R62A) B*2705 and B*2709 mutants that showed an overall reduction in their capability to present peptides to CD8+ T cells. Moreover, major subtype-dependent differences in the peptide recognition suggest distinct TCR binding modes for the B*2705 versus the B*2709 subtype

Exploring new physics frontiers through numerical relativity

The demand to obtain answers to highly complex problems within strong-field gravity has been met with significant progress in the numerical solution of Einstein's equations - along with some spectacular results - in various setups. We review techniques for solving Einstein's equations in generic spacetimes, focusing on fully nonlinear evolutions but also on how to benchmark those results with perturbative approaches. The results address problems in high-energy physics, holography, mathematical physics, fundamental physics, astrophysics and cosmology

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Acesso realizado ao Programa de Saúde da Família em área com "alta" cobertura do subsistema privado Access to the Family Healthcare Program in an area with "extensive" coverage of the private healthcare system

O perfil do acesso realizado aos distintos serviços ofertados pelo PSF em área com importante cobertura do sistema privado é identificado em unidade de saúde na cidade de Santo André, estado de São Paulo. A amostra, em duas fases, foi delineada partindo do pressuposto de que o uso possível das atividades ofertadas pela estratégia saúde da família não é uniforme, com base neste uso foram considerados três grupos populacionais: residual, parcial e completo. Foram entrevistadas 175 pessoas, a população cadastrada é composta por 0,5% de usuários com perfil completo, 31,0% parcial e 68,5% residual. Na análise bivariada observaram-se diferenças significantes entre os grupos parcial e residual em relação à idade, renda, trabalho, afiliação ao subsistema privado e anos de escolaridade. No entanto, as razões de prevalência, quando estimadas por meio do modelo múltiplo de Poisson indicam que os fatores que influem no perfil de acesso são afiliação ao subsistema privado e renda. Chama atenção que alguns serviços ofertados não alcancem mais de 20% da população cadastrada. Apesar da imensa potencialidade das propostas inovadoras incorporadas pelo PSF, observa-se uso seletivo de suas atividades pela população, fortemente influenciado pela afiliação ao subsistema privado e pela renda.<br>The access profile to the various services offered by the Family Health Program (PSF) in an area with extensive private health system coverage is studied in the city of Santo André, state of São Paulo. The sample was studied in two phases based on the assumption that the use of the activities offered by the Family Health Program is not uniform. Residual, full and partial population groups were therefore considered. Interviews were conducted with 175 individuals and the registered population is composed of full (0.5%), partial (31.0%) and residual (68.5%) users. In the bivariate analysis, significant differences were observed between partial and residual groups in relation to age, income, employment, affiliation to the private subsystem and years of schooling. However, the ratios of prevalence when estimated by the Poisson multiple model indicate that the factors that influence the access profile of the PSF activities are private subsystem membership and income. This highlights the fact that some services offered do not reach more than 20% of the population. Despite the immense potential of innovative proposals incorporated by the PSF, this study shows that there is selective use of its activities by the population, strongly influenced by private subsystem affiliation and income