Inter-test reproducibility of the lung clearance index measured by multiple breath washout

Background: Traditionally the inter-test reproducibility of the lung clearance index (LCI) has been described in terms of absolute change (e.g. 1 unit), however, if LCI is more variable at higher values, interpretation of absolute changes in LCI may be biased. Aims: We assessed whether inter-test reproducibility depends on the LCI value and whether relative changes are better suited to define reproducibility. Methods: Multiple breath nitrogen washout (MBW) was measured at baseline, 1, 3, 6, 9 and 12 months in children aged 3-6 years with CF, and age-matched healthy controls. Reproducibility of the LCI between each pair of measurements was described using Bland Altman limits of agreement (LA), Coefficient of repeatability (CR), and relative change. Results: 148 children contributed 619 MBW measurements. The within-subject SD of the LCI between paired measurements, a measure of variability, increased as the absolute LCI increased. Therefore, using LA or the CR to determine thresholds of inter-test reproducibility will over-estimate clinically relevant changes in patients with higher LCI values. Using relative changes, a physiologically or clinically relevant change in healthy preschool children was calculated to be +/- 15%, whereas it was +/- 30% in CF children. The average relative change in both health and CF was independent of the time interval between measurements. Conclusions: Since LCI variability is proportional to its mean, interpretation of absolute changes will be biased. Changes in LCI greater than +/- 15% can be considered greater than the biological variability of the test in health and may help to identify patients with clinically relevant changes in lung function

Patient-centered approach and non-pharmaceutical interventions (NPIs) in general practice

L’essor des interventions non médicamenteuses (INM) a du sens et interpelle sur les besoins et les attentes des médecins et des usagers. Ces solutions de santé, nées de bouleversements sociétaux et économiques, doivent être « repensées » pour être intégrées dans des parcours de soins coordonnés. L’approche centrée patient est au coeur de cette démarche. La communauté médicale territoriale, en particulier les acteurs des soins primaires, doit se mobiliser pour élaborer des modalités d’enseignement et d’évaluation de ces INM par une recherche appropriée.The rise of non-pharmacological interventions (NPIs) makes sense and challenges the needs and expectations of physicians and users. These health solutions, born of societal and economic upheavals, must be “redesigned” to be integrated into coordinated care pathways. The patient-centered approach is at the heart of this approach. The territorial medical community, especially primary care stakeholders, must mobilize to develop methods for teaching and evaluating these NPIs through appropriate research

An Automated Method to Quantify Microglia Morphology and Application to Monitor Activation State Longitudinally In Vivo

Microglia are specialized immune cells of the brain. Upon insult, microglia initiate a cascade of cellular responses including a characteristic change in cell morphology. To study the dynamics of microglia immune response in situ, we developed an automated image analysis method that enables the quantitative assessment of microglia activation state within tissue based solely on cell morphology. Per cell morphometric analysis of fluorescently labeled microglia is achieved through local iterative threshold segmentation, which reduces errors caused by signal-to-noise variation across large volumes. We demonstrate, utilizing systemic application of lipopolysaccharide as a model of immune challenge, that several morphological parameters, including cell perimeter length, cell roundness and soma size, quantitatively distinguish resting versus activated populations of microglia within tissue comparable to traditional immunohistochemistry methods. Furthermore, we provide proof-of-concept data that monitoring soma size enables the longitudinal assessment of microglia activation in the mouse neocortex imaged via 2-photon in vivo microscopy. The ability to quantify microglia activation automatically by shape alone allows unbiased and rapid analysis of both fixed and in vivo central nervous system tissue

Facilitated Monocyte-Macrophage Uptake and Tissue Distribution of Superparmagnetic Iron-Oxide Nanoparticles

BACKGROUND: We posit that the same mononuclear phagocytes (MP) that serve as target cells and vehicles for a host of microbial infections can be used to improve diagnostics and drug delivery. We also theorize that physical and biological processes such as particle shape, size, coating and opsonization that affect MP clearance of debris and microbes can be harnessed to facilitate uptake of nanoparticles (NP) and tissue delivery. METHODS: Monocytes and monocyte-derived macrophages (MDM) were used as vehicles of superparamagnetic iron oxide (SPIO) NP and immunoglobulin (IgG) or albumin coated SPIO for studies of uptake and distribution. IgG coated SPIO was synthesized by covalent linkage and uptake into monocytes and MDM investigated related to size, time, temperature, concentration, and coatings. SPIO and IgG SPIO were infused intravenously into naïve mice. T(2) measures using magnetic resonance imaging (MRI) were used to monitor tissue distribution in animals. RESULTS: Oxidation of dextran on the SPIO surface generated reactive aldehyde groups and permitted covalent linkage to amino groups of murine and human IgG and F(ab')(2) fragments and for Alexa Fluor(R) 488 hydroxylamine to form a Schiff base. This labile intermediate was immediately reduced with sodium cyanoborohydride in order to stabilize the NP conjugate. Optical density measurements of the oxidized IgG, F(ab')(2), and/or Alexa Fluor(R) 488 SPIO demonstrated approximately 50% coupling yield. IgG-SPIO was found stable at 4 degrees C for a period of 1 month during which size and polydispersity index varied little from 175 nm and 200 nm, respectively. In vitro, NP accumulated readily within monocyte and MDM cytoplasm after IgG-SPIO exposure; whereas, the uptake of native SPIO in monocytes and MDM was 10-fold less. No changes in cell viability were noted for the SPIO-containing monocytes and MDM. Cell morphology was not changed as observed by transmission electron microscopy. Compared to unconjugated SPIO, intravenous injection of IgG-SPIO afforded enhanced and sustained lymphoid tissue distribution over 24 hours as demonstrated by MRI. CONCLUSIONS: Facilitated uptake of coated SPIO in monocytes and MDM was achieved. Uptake was linked to particle size and was time and concentration dependent. The ability of SPIO to be rapidly taken up and distributed into lymphoid tissues also demonstrates feasibility of macrophage-targeted nanoformulations for diagnostic and drug therapy

Identification of Cellular Infiltrates during Early Stages of Brain Inflammation with Magnetic Resonance Microscopy

A comprehensive view of brain inflammation during the pathogenesis of autoimmune encephalomyelitis can be achieved with the aid of high resolution non-invasive imaging techniques such as microscopic magnetic resonance imaging (μMRI). In this study we demonstrate the benefits of cryogenically-cooled RF coils to produce μMRI in vivo, with sufficient detail to reveal brain pathology in the experimental autoimmune encephalomyelitis (EAE) model. We could visualize inflammatory infiltrates in detail within various regions of the brain, already at an early phase of EAE. Importantly, this pathology could be seen clearly even without the use of contrast agents, and showed excellent correspondence with conventional histology. The cryogenically-cooled coil enabled the acquisition of high resolution images within short scan times: an important practical consideration in conducting animal experiments. The detail of the cellular infiltrates visualized by in vivo μMRI allows the opportunity to follow neuroinflammatory processes even during the early stages of disease progression. Thus μMRI will not only complement conventional histological examination but will also enable longitudinal studies on the kinetics and dynamics of immune cell infiltration

Magnetic resonance imaging of monocyte infiltration in an animal model of multiple sclerosis

The aim of this research was to study neuroinflammatory processes and more specifically the infiltration of monocytes in the central nervous system (CNS) in an animal model of multiple sclerosis (MS) using magnetic resonance imaging (MRI). Monocytes play a key role in MS pathology, and the study of their infiltration kinetics in vivo would benefit from a non-invasive imaging strategy. Initially, to visualize monocytes with MRI, we investigated different labeling strategies in human monocytes using super paramagnetic particles of iron oxide (SPIO, diameter > 50nm) and ultra small SPIO (USPIO, diameter 20 – 50nm). Histological analysis and MR validation showed that monocytes are labeled more efficiently using the larger SPIO compared to USPIO. Importantly, our optimal labeling condition allowed detection of monocytes by MRI without compromising important physiological cell functions like cell viability, migratory capacity and cytokine production. Subsequently, we used SPIO to label freshly isolated rat monocytes. Cell tracking experiments were performed in a rat model of neuroinflammation and we directly compared two main approaches of in vivo monocyte imaging: (1) Intravenous injection of monocytes that were labeled ex vivo with SPIO versus (2) the administration of free USPIO. In theory, free USPIO are taken up in the blood stream by circulating monocytes. Using method 1, we demonstrated longitudinal MR detection of SPIO-labeled monocytes that migrate towards an inflammatory site in the brain. Interestingly, method 2 resulted in an early decrease of signal intensity in the lesion (2 hours) and pointed to the detection of blood-brain barrier (BBB) leakage instead of monocyte migration. To monitor monocyte migration in the experimental model of MS in rats (experimental autoimmune encephalomyelitis; EAE), we had to introduce a novel labeling strategy: Magneto-Electroporation (MEP). Our results showed that an intravenous injection of monocytes labeled using MEP resulted in multiple foci of signal loss, predominantly in the white matter of the cerebellum in EAE rats. Therefore, MEP is essential to visualize the dynamic process of monocyte infiltration in pathologies with multiple small lesions in the CNS, as in case of MS. Complementary to our previous studies, we also focused on the administration of free USPIO in EAE rats. We found that USPIO enter the brain parenchyma of EAE rats within 1 hour whereas at 72 hours after injection, MR abnormalities were no longer present in the CNS. Subsequent imaging of the cervical lymph nodes revealed USPIO accumulation. Our data strongly suggest that the process of leakage over the BBB has to be considered next to cellular infiltration when interpreting post-USPIO MR images. Moreover, in this study we identified the potential use of USPIO-enhanced MRI to study non-invasively drainage in the inflammatory brain. In a clinical trial, we administered a novel USPIO to MS patients and compared enhancement patterns in the brain with enhancement obtained after conventional Gd-DTPA injections. We showed that USPIO enhancements were more frequently observed and several types of enhancement patterns could be distinguished and correlated to certain stages of lesion development. In conclusion, cellular MRI using iron oxide particles is a valuable tool to study the multiple aspects of inflammation in MS and may lead to effective treatment protocols for drugs that limit monocyte entry during neuroinflammation

En quoi, une théorie sémiopragmatique à partir des théories de Peirce peut-elle renouveler la recherche en sciences humaines et sociales ?

Dans le champ des Sciences Humaines et Sociales, l’analyse textuelle est une procédure essentielle des approches qualitatives. Notre objectif est de proposer une méthode sémiopragmatique inédite dans l’analyse de verbatims. Les écrits de CS Peirce, philosophe américain, père du pragmatisme, de la sémiotique et concepteur du raisonnement abductif en sont les fondements. Les procédures d’analyse se résument en 3 étapes : décrire et analyser le texte en y repérant les classes de signes élémentaires ; Ordonner les données empiriques en catégories de sens selon la logique des relations-signes ; Produire un sens global à partir de la catégorie-argument. Cette méthode apporte un moment formel à l’analyse en permettant une mise en ordre logique des catégories empiriques limitant le risque de biais d’interprétation liés à l’investigateur. Elle pourrait éclairer les zones d’ombre autour du moment interprétatif et du raisonnement sous-jacent, critique récurrente des approches qualitatives.In the fields of Human and Social Sciences, textual analysis is the core process of qualitative approachs. Our aim is to offer a semiopramatic method to analyse. The writings of CS Peirce, american philopsophe, father of pragmatisme and semiotics and inventor of abductive reasoning are the foundations.This method can be summarized in three stages : analyzing the text in elementary classes of signs ; ordoning empirical data and constructing categories of meaning according to logical relationship ; providing a comprehensive meaning. This method add a formal moment to the analyze and allow the logical ordering of these empirical categories according to Peirce’s classes of signs by limiting investigator-related interpretation bias. This method could illuminate the « shadow zones» regarding interpretative process and the underlying reasoning, usual criticism of qualitative researchs.En el campo de las Ciencias Humanas y Sociales, el análisis del texto es un procedimiento esencial del método cualitativo. Nuestro objetivo es el de proponer un método semio -pragmático inédito en el análisis de los verbatims y analizar los escritos de CS Peirce, filósofo americano, padre del pragmatismo, de la semiología junto a los fundamentos del concepto de razonamiento abductivo. Los procesos de análisis pueden resumirse en tres etapas: describir y analizar el texto, poniendo énfasis en las clases de signos elementales; ordenar los datos empíricos en categorías de sentido según la lógica de la relación-signo; producir un sentido global a partir de la categoría-argumento. Este método aporta un momento formal al análisis, permitiendo una puesta en orden lógico de las categorías empíricas, limitando el riesgo de ser influenciado por las interpretaciones del investigador. Este método puede esclarecer las zonas no-claras que aparecen en el momento interpretativo y del razonamiento subyacente, critica recurrente que se realiza al método cualitativo