L'IRM s'aventure hors des sentiers du monde médical

National audienceL'agroalimentaire et le génie civil constituent deux domaines d'applications très particuliers pour l'imagerie par résonance magnétique (IRM). Essentiellement axées sur les problèmes d'élaboration, de conditionnement et d'évolution de produits et de matériaux en contexte industriel, les études doivent souvent être menées sur des échantillons massifs. Elles mettent en oeuvre des imageurs de grande taille et réclament le développement de méthodologies spécifiques par rapport aux applications médicales. Des systèmes originaux d'instrumentation et de sollicitation in situ des matériaux ont pu être conçus dans ce cadre, nourris par des collaborations étroites entre différents corps de métiers. Deux laboratoires, l'Unité Technologie des équipements agroalimentaires de l'Irstea et le Laboratoire Navier de l'Université Paris-Est, livrent leur témoignage, fruit de plusieurs années d'expertise. Food-processing and civil engineering are very particular application fields for magnetic resonance imaging (MRI). Studies mainly focus on preparation, packaging, and further evolution of products and materials in industry. They are often carried out on massive samples. They involve the use of large MRI facilities, and require the development of specific methodology as compared with routine medical studies. Stimulating close collaborations between various technical specialties, they saw the raise of original experimental setups for in situ measurements and sample solicitations. Two French laboratories, the " Technologie des équipements agroalimentaires " Unity at Irstea and " Laboratoire Navier " at Paris-Est University, report on their long standing expertise

Search for an Association between V249I and T280M CX3CR1 Genetic Polymorphisms, Endothelial Injury and Preeclampsia: The ECLAXIR Study

BACKGROUND: Preeclampsia and coronary-artery disease share risk factors, suggesting common pathophysiological mechanisms. CX3CR1/CX3CL1 mediates leukocyte migration and adhesion and has been implicated in the pathophysiology of several inflammatory diseases. M280/I249 variants of CX3CR1 are associated with an atheroprotective effect and reduced endothelial dysfunction. The aim of this study was to search for an association between V249I and T280M polymorphisms of CX3CR1, preeclampsia and endothelial dysfunction. METHODOLOGY/PRINCIPAL FINDINGS: We explored these polymorphisms with real-time polymerase chain reaction in a case-control study (184 white women with preeclampsia and 184 matched normotensive pregnant women). Endothelial dysfunction biomarkers including von Willebrand factor, VCAM-1 and thrombomodulin, as well as the soluble form of CX3CL1 were measured by enzyme-linked immunosorbent assays (ELISA). The I249 and M280 alleles were associated neither with preeclampsia, nor with its more severe form or with endothelial injury. In contrast, we found a trend toward increased CX3CL1 levels in preeclampsia patients, especially in early-onset- preeclampsia as compared to its level in later-onset- preeclampsia. CONCLUSIONS/SIGNIFICANCE: This is the first study to characterize the CX3CR1 gene polymorphisms in patients with preeclampsia. We found no differences in genotype or haplotype frequencies between patients with PE and normal pregnancies, suggesting that maternal CX3CR1 V249I and T280M polymorphisms do not increase susceptibility to preeclampsia. Further studies should be performed to directly evaluate the pathophysiological role of CX3CL1, a molecule abundantly expressed in endometrium, which has been shown to stimulate human trophoblast migration

Causal effect of plasminogen activator inhibitor type 1 on coronary heart disease

Background--Plasminogen activator inhibitor type 1 (PAI-1) plays an essential role in the fibrinolysis system and thrombosis. Population studies have reported that blood PAI-1 levels are associated with increased risk of coronary heart disease (CHD). However, it is unclear whether the association reflects a causal influence of PAI-1 on CHD risk. Methods and Results--To evaluate the association between PAI-1 and CHD, we applied a 3-step strategy. First, we investigated the observational association between PAI-1 and CHD incidence using a systematic review based on a literature search for PAI-1 and CHD studies. Second, we explored the causal association between PAI-1 and CHD using a Mendelian randomization approach using summary statistics from large genome-wide association studies. Finally, we explored the causal effect of PAI-1 on cardiovascular risk factors including metabolic and subclinical atherosclerosis measures. In the systematic meta-analysis, the highest quantile of blood PAI-1 level was associated with higher CHD risk comparing with the lowest quantile (odds ratio=2.17; 95% CI: 1.53, 3.07) in an age- and sex-adjusted model. The effect size was reduced in studies using a multivariable-adjusted model (odds ratio=1.46; 95% CI: 1.13, 1.88). The Mendelian randomization analyses suggested a causal effect of increased PAI-1 level on CHD risk (odds ratio=1.22 per unit increase of log-transformed PAI-1; 95% CI: 1.01, 1.47). In addition, we also detected a causal effect of PAI-1 on elevating blood glucose and high-density lipoprotein cholesterol. Conclusions--Our study indicates a causal effect of elevated PAI-1 level on CHD risk, which may be mediated by glucose dysfunction

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Mathematical modelling of uniaxial extension of a heterogeneous gas cell wall in bread dough: Stress fields and stress concentration analysis relating to the proving and baking steps

International audienceA mathematical model was developed to increase the understanding of stress concentrations within a gas cell wall (GCW) in bread dough during baking. The GCW was composed of a single A-type wheat starch granule surrounded by various proportions of gluten typical of GCWs when about to rupture. Finite element simulations were carried out in 2D using linear viscoelasticity and visco-hyperelasticity. Strain orders of magnitude and rates relevant to dough during baking were applied as boundary conditions for two plausible sets of mechanical properties before and after protein coagulation and starch gelatinization (T 70-80 degrees C). The average stress within the GCW was found to be strongly dependent on the starch fraction. Gluten-starch interactions influenced average stress values considerably when the starch fraction was greater than 11% v/v. The locations within the GCW where rupture was most likely to be initiated were identified by mapping maximal stress points using stress field and triaxiality analysis and the findings were discussed

Modelling of baking processes

Baking involves many coupled phenomena occurring inside and outside the food product. This chapter examines how the food product can be described in terms of phases and components and how the heat, mass and momentum transfer can be modelled in a more or less simplified manner. The simplification assumptions mainly depend on the question to be answered. Two modelling examples are given. The conclusion focuses on trends and future challenges in the modelling of baking processes

CLSM study of layers in laminated dough: Roll out of layers and elastic recoil

International audienceIt has been thought that all fat and dough layers in laminated dough had the same thickness at the end of lamination. Moreover dough rheology (taking into account elastic recoil) is too complex to generalize calculation of the final thickness of the dough after lamination. Confocal laser scanning microscopy can differentiate the fat from the dough when combined with fluorophore staining (Nile Red and Alexa), and an algorithm was applied to quantify their respective thicknesses. When fat consistency was close to that of dough, the median thickness of fat was fairly close to theoretical values. Successive sheeting steps resulted in homogenization of layer thicknesses. The surface area of fat in relation to paste was greater than expected, especially follow numbers of sheeting steps, and also for samples with higher numbers of sheeting steps, presenting an exceptionally thick layer of fat (including that produced by back flow). Elastic recoil was between 20 and 90% higher than the targeted roll out; no significant effect of a harder fat consistency was found. Elastic recoil was less when the amount of fat in the sample was greater

Estimating fat, paste and gas in a proving Danish paste by MRI – Description of the method and evaluation of its performances (bias and accuracy, sensitivity threshold)

This paper presents a method to characterize the development of the structures of puff pastries during proving using MRI. Since the resolution is large, each pixel contains an unknown proportion of three components: fat, paste and gas. The signal to noise ratio is low since gas which reaches 80% at the end of proving gives no signal. The signal is the sum of reference signals, corresponding to pixels filled with one component, weighted by the proportions. The reference signals were supposed to be known. We adopted an edge-preserving approach based on the minimization of a penalized least-square criterion. This criterion is the weighted sum of a term accounting for the fidelity to data and a regularization term. The minimization of the criterion is based on a non-linear conjugate gradient algorithm. The settings of the weights of the two terms is based on simulations. Then simulation results are presented. The mean error was similar with or without regularization and depended on the components and their proportion (less that 1% up to 6%). Fat and gas proportions were overestimated, paste proportion was underestimated. The dispersion of the results was lower with regularization (from 0.3% up to 1.5 %). Monte-Carlo simulations showed that these results were not influenced very much by the uncertainty on the reference signals at the end of the proving. Larger uncertainties were found at the beginning of proving. We showed that the regularization of the solutions did improve the visualization of the structures confirming the interest of this approach.We also found that layers down to 40 microns thick and bubbles of which size exceeded 2.5mm could be easily distinguished in fat and gas proportion maps respectively. Experiments on genuine MRI images of Danish paste confirmed the results obtained with the simulation study. We were able to validate the method at the scale of the Danish paste by observing the evolution of the sum of the fat proportion over time, as well as the evolution of the gas content compared with the evolution of the size of the pastry. This confirmed the possibility to use the method to study the proving of a Danish paste

Multi-tissue partial volume quantification in multi-contrast MRI using an optimised spectral unmixing approach

International audienc