Modeling diffusion of intracellular metabolites in the mouse brain up to very high diffusion-weighting: Diffusion in long fibers (almost) accounts for non-monoexponential attenuation

Purpose: To investigate how intracellular metabolites diffusion measured in vivo up to very high q/b in the mouse brain can be explained in terms of simple geometries. / Methods: 10 mice were scanned using our new STE‐LASER sequence, at 11.7 Tesla (T), up to qmax = 1 μm−1 at diffusion time td = 63.2 ms, corresponding to bmax = 60 ms/µm². We model cell fibers as randomly oriented cylinders, with radius a and intracellular diffusivity urn:x-wiley:07403194:media:mrm26548:mrm26548-math-0004, and fit experimental data as a function of q to estimate urn:x-wiley:07403194:media:mrm26548:mrm26548-math-0005 and a. / Results: Randomly oriented cylinders account well for measured attenuation, giving fiber radii and urn:x-wiley:07403194:media:mrm26548:mrm26548-math-0006 in the expected ranges (0.5–1.5 µm and 0.30–0.45 µm2/ms, respectively). The only exception is N‐acetyl‐aspartate (NAA) (extracted a∼0), which we show to be compatible with a small fraction of the NAA pool being confined in highly restricted compartments (with short T2). / Conclusion: The non‐monoexponential signal attenuation of intracellular metabolites in the mouse brain can be described by diffusion in long and thin cylinders, yielding realistic Dintra and fiber diameters. However, this simple model may require small “corrections” for NAA, in the form of a small fraction of the NAA signal originating from a highly restricted compartment

The influence of a formula supplemented with dairy lipids and plant oils on the erythrocyte membrane omega-3 fatty acid profile in healthy full-term infants : a double-blind randomized controlled trial

BACKGROUND: Human milk is the optimal nutrition for infants. When breastfeeding is not possible, supplementation of infant formula with long chain polyunsaturated fatty acids appears to promote neurodevelopmental outcome and visual function. Plant oils, that are the only source of fat in most of infant formulas, do not contain specific fatty acids that are present in human and cow milk and do not encounter milk fat triglyceride structure. Experimental data suggest that a mix of dairy lipids and plant oils can potentiate endogenous synthesis of n-3 long chain polyunsaturated fatty acids. This trial aims to determine the effect of an infant formula supplemented with a mixture of dairy lipids and plant oils on the erythrocyte membrane omega-3 fatty acid profile in full-term infants (primary outcome). Erythrocyte membrane long chain polyunsaturated fatty acids and fatty acids content, the plasma lipid profile and the insulin-growth factor 1 level, the gastrointestinal tolerance, the changes throughout the study in blood fatty acids content, in growth and body composition are evaluated as secondary outcomes. METHODS/DESIGN: In a double-blind controlled randomized trial, 75 healthy full-term infants are randomly allocated to receive for four months a formula supplemented with a mixture of dairy lipids and plant oils or a formula containing only plant oils or a formula containing plant oils supplemented with arachidonic acid and docosahexaenoic acid. Twenty-five breast-fed infants constitute the reference group. Erythrocyte membrane omega-3 fatty acid profile, long chain polyunsaturated fatty acids and the other fatty acids content, the plasma lipid profile and the insulin-growth factor 1 level are measured after four months of intervention. Gastrointestinal tolerance, the changes in blood fatty acids content, in growth and body composition, assessed by means of an air displacement plethysmography system, are also evaluated throughout the study. DISCUSSION: The achievement of an appropriate long chain polyunsaturated fatty acids status represents an important goal in neonatal nutrition. Gaining further insight in the effects of the supplementation of a formula with dairy lipids and plant oils in healthy full-term infants could help to produce a formula whose fat content, composition and structure is more similar to human milk. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01611649

Dynamical representation of dominance relationships in the human rostromedial prefrontal cortex

Humans and other primates have evolved the ability to represent their status in the group's social hierarchy, which is essential for avoiding harm and accessing resources. Yet it remains unclear how the human brain learns dominance status and adjusts behavior accordingly during dynamic social interactions. Here we address this issue with a combination of fMRI and transcranial direct current stimulation (tDCS). In a first fMRI experiment, participants learned an implicit dominance hierarchy while playing a competitive game against three opponents of different skills. Neural activity in the rostromedial PFC (rmPFC) dynamically tracked and updated the dominance status of the opponents, whereas the ventromedial PFC and ventral striatum reacted specifically to competitive victories and defeats. In a second experiment, we applied anodal tDCS over the rmPFC to enhance neural excitability while subjects performed a similar competitive task. The stimulation enhanced the relative weight of victories over defeats in learning social dominance relationships and exacerbated the influence of one's own dominance over competitive strategies. Importantly, these tDCS effects were specific to trials in which subjects learned about dominance relationships, as they were not present for control choices associated with monetary incentives but no competitive feedback. Taken together, our findings elucidate the role of rmPFC computations in dominance learning and unravel a fundamental mechanism that governs the emergence and maintenance of social dominance relationships in humans

Relationships between serotonin transporter rate and brain activity associated with learning of social ranks: a simultaneous TEP([11C]-DASB)-fMRI study in humans

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Testosterone affects learning of implicit social dominance relationships from competitive interaction

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Bolus quality and food comfortability of model cheeses for the elderly as influenced by their texture

International audienceThe aim of this study was to examine the influence of the texture of dairy products on bolus properties and food comfortability as perceived by elderly persons. Four cheese models identical in terms of their nutritional composition but different by the type of texture (Soft, Hard, Processed and Whipped) were developed to resemble market cheese. Study was performed with a panel of 38 elderly persons without dental impairment but with variable rate of saliva flow. The time of chewing required to form the bolus was measured. The rheological properties of the bolus obtained were studied as well as the quantity of saliva incorporated. Food comfortability was assessed by means of a questionnaire asking about in-mouth comfort, bolus formation, pain, and perceived texture and flavor. Results showed that food comfortability was positively correlated to the ease of forming the bolus which depended on the food texture. Thus, the bolus formed with the Whipped product which required more saliva, was harder than the other three products and so judged the least comfortable. This product was characterized by a dry and sticky texture. On the other hand, the Soft and Processed products led to a softer food bolus that was more easily formed, and thus were judged as more comfortable. Their textures were perceived as soft, fatty and melting. This work highlights the importance of considering food bolus formation and related properties when looking for the link between food product characteristics and the enjoyment of eating in the case of the elderly population

Efficacité d'une eau gélifiée et d'une poudre épaississante destinées aux patients dysphagiques aux liquides.

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Validité des équations prédictives de la dépense énergétique de repos développées pour le patient obèse : impact de la technique de mesure de composition corporelle utilisée

International audienceIntroduction et but de l’étudeDes formules ont spécifiquement été développées pour le patient obèse afin de prédire la dépense énergétique de repos (DER) et ainsi d’adapter au mieux les apports nutritionnels des patients. Certaines de ces équations nécessitent une mesure de la composition corporelle. Les valeurs de DER mesurées ont été comparées aux résultats issus des prédictions d’équations prédictives en fonction de la technique de mesure de composition corporelle utilisée, absorptiométrie à rayons X (DEXA) ou impédancemétrie bioélectrique (BIA).Matériel et méthodesLes équations prédictives de DER développées pour le patient obèse ont été appliquées sur une population de patients suivis dans une unité de nutrition. Après une période de jeûne de 12 h, la DER a été mesurée par calorimétrie indirecte (Deltatrac II ou Quark RMR) en décubitus dorsal pendant 30 min et la composition corporelle des patients a été évaluée par BIA (Bodystat Quadscan 4000) et par DEXA (Lunar Prodigy Advance). La DER, le pourcentage de bonne prédiction (± 10 %/DER mesurée) et le biais (Bland–Altman, %) ont été calculés et comparés.Résultats et analyse statistiqueLes formules de prédiction ont pu être étudiées sur une population de 2588 patients obèses (38,1 ± 5,3 kg.m−2 ; 46,2 ± 14,2 ans), dont 2073 femmes et 515 hommes. La DER mesurée moyenne était de 1788 ± 321 kcal/24 h. L’équation de Bernstein ne permet pas d’obtenir de bonnes valeurs de prédiction quelle que soit la technique de mesure de composition corporelle (< 20 %, Tableau 1). Au contraire, les équations de Huang et de Müller ont présenté de meilleurs résultats de bonne prédiction (Tableau 1). En effet, en utilisant la BIA, une bonne prédiction était retrouvée dans 67,6 et 67,1 % des cas avec les équations de Huang et de Müller, respectivement. L’utilisation de la DEXA était associée à une diminution de ces pourcentages à 59,7 et 65,9 %, respectivement. Les résultats étaient similaires en analysant les données par classe d’IMC (obésité de grade I + II et de grade III, données non montrées). Seule l’équation de Müller (avec BIA) permet d’obtenir une DER moyenne non différente de la DER mesurée (Tableau 1).ConclusionDans notre population de patients obèses, l’utilisation de l’impédancemétrie bioélectrique permet d’obtenir de meilleurs résultats de prédiction de la DER que la DEXA, en particulier pour l’équation de Huang

L. fermentum CECT 5716 prevents stress-induced intestinal barrier dysfunction in newborn rats

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