39 research outputs found
La stimulation de la cĂ©togenĂšse par la prise de diffĂ©rents supplĂ©ments alimentaires : carnitine, leucine, butyrate et monoglycĂ©ride dâoctanoate
Introduction : Un hypomĂ©tabolisme du glucose au cerveau peut apparaĂźtre des dĂ©cennies avant le diagnostic de maladie dâAlzheimer. Pourtant, le mĂ©tabolisme des cĂ©tones, le carburant alternatif principal au glucose, nâest pas altĂ©rĂ©, autant chez les personnes plus ĂągĂ©es que chez les personnes atteintes de la maladie dâAlzheimer. Les mĂ©thodes connues (diĂšte cĂ©togĂšne, jeĂ»ne, huile de triglycĂ©rides de moyennes chaĂźnes) pour augmenter la production de cĂ©tones comportent leurs inconvĂ©nients. Lâobjectif de ces projets Ă©tait de vĂ©rifier lâefficacitĂ© de produits commerciaux vendus Ă cet effet et dâĂ©valuer dâautres molĂ©cules qui pourraient ĂȘtre utilisĂ©es pour leur propriĂ©tĂ© cĂ©togĂšne. Ce sont des supplĂ©ments alimentaires pouvant servir de substrat pour la cĂ©togenĂšse (butyrate, monoglycĂ©ride dâoctanoate (O-MAG), leucine) ou de facilitateur du transport des acides gras (carnitine).
MĂ©thodes : Pour ce faire, les participants devaient se prĂ©senter au laboratoire pour plusieurs demi-journĂ©es dâĂ©tude dâune durĂ©e de 4 heures. Lors de ces journĂ©es, un des supplĂ©ments leur Ă©tait servi avec un dĂ©jeuner et des prises de sang Ă©taient effectuĂ©es toutes les 30 minutes. RĂ©sultats : Le produit commercial contenant des MCT, le butyrate, lâO-MAG et la leucine ont permis dâaugmenter respectivement les concentrations maximales en cĂ©tones plasmatiques de 568, 226, 67 et 70 ”mol/L (pâ€0,05) par rapport au contrĂŽle. De plus, la concentration plasmatique en octanoate Ă©tait corrĂ©lĂ©e significativement avec la concentration sanguine dâacĂ©toacĂ©tate (r=0,85 ; p <0,0001) et de ÎČ-hydroxybutyrate (r=0,58 ; p=0,01). Lâaire sous la courbe par gramme de produit ingĂ©rĂ© montre que le butyrate Ă©tait le supplĂ©ment cĂ©togĂšne le plus efficace et Ă©tait plus cĂ©togĂšne que le produit commercial, lâO-MAG et la leucine (p=0,009).
Discussion : Le butyrate Ă©tait 3 fois plus cĂ©togĂšne que tous les autres supplĂ©ments testĂ©s. Par contre, son ingestion a causĂ© quelques effets secondaires Ă certains participants. La leucine a Ă©tĂ© le seul supplĂ©ment Ă ne crĂ©er aucun inconfort chez les participants. Il faudrait donc Ă©tudier la possibilitĂ© de combiner plusieurs molĂ©cules dans un supplĂ©ment chimiquement pensĂ© pour ĂȘtre le plus efficace possible et pour ĂȘtre intĂ©ressant lors dâune utilisation quotidienne
Analyse des concepts liĂ©s Ă lâhĂ©tĂ©rogĂ©nĂ©itĂ© pour Ă©laborer un modĂšle de dĂ©cloisonnement de la classe
Cet essai sâintĂ©resse Ă lâhĂ©tĂ©rogĂ©nĂ©itĂ© de la classe ainsi quâaux difficultĂ©s vĂ©cues par les enseignants au prĂ©scolaire et au primaire en lien avec la diffĂ©renciation pĂ©dagogique. La motivation de lâĂ©lĂšve et lâactivitĂ© pĂ©dagogique sont aussi soulevĂ©es dans cette problĂ©matique. Ainsi, pour rĂ©flĂ©chir Ă cette problĂ©matique, lâauteure de cet essai veut Ă©laborer un modĂšle pĂ©dagogique de planification favorisant des pratiques variĂ©es, diffĂ©renciĂ©es et adaptĂ©es Ă l'hĂ©tĂ©rogĂ©nĂ©itĂ© de la classe. Pour y parvenir, elle a ciblĂ© deux objectifs soit de dĂ©finir les concepts clĂ©s pour dĂ©gager les caractĂ©ristiques du modĂšle pĂ©dagogique et dâanalyser les concepts clĂ©s nĂ©cessaires pour favoriser des pratiques variĂ©es, diffĂ©renciĂ©es et adaptĂ©es Ă l'hĂ©tĂ©rogĂ©nĂ©itĂ© de la classe. Le deuxiĂšme chapitre aborde les concepts dâhĂ©tĂ©rogĂ©nĂ©itĂ©, de modĂšle pĂ©dagogique, des stratĂ©gies pĂ©dagogiques dĂ©coulant de diffĂ©rentes thĂ©ories, de la diffĂ©renciation pĂ©dagogique, du modĂšle de rĂ©ponse Ă lâintervention et du dĂ©cloisonnement. Ces concepts sont dĂ©finis de façon Ă pouvoir Ă©laborer le modĂšle et accompagner lâanalyse de ce dernier. Le dernier chapitre consiste Ă lâanalyse du modĂšle. Les principaux constats qui ressortent de cette analyse sont que le modĂšle pĂ©dagogique Ă©laborĂ© facilite la gestion de lâhĂ©tĂ©rogĂ©nĂ©itĂ© de la classe et quâil permet aux enseignants de rĂ©pondre aux besoins de chacun des Ă©lĂšves et de garder ces derniers motivĂ©s. En conclusion cet essai permet dâoffrir un outil de planification aux enseignants afin de favoriser des pratiques variĂ©es, diffĂ©renciĂ©es et adaptĂ©es Ă l'hĂ©tĂ©rogĂ©nĂ©itĂ© de la classe
Le risque de dĂ©crochage scolaire et la participation Ă des activitĂ©s parascolaires Ă lâĂ©cole secondaire : effets mĂ©diateurs des symptĂŽmes dĂ©pressifs et des problĂšmes de comportement extĂ©riorisĂ©s
Cette étude vise à examiner si les symptÎmes dépressifs et les problÚmes de comportement
extĂ©riorisĂ©s agissent Ă titre de mĂ©diateurs du lien entre lâintensitĂ© de participation Ă des activitĂ©s
parascolaires et le risque de dĂ©crochage scolaire Ă lâĂ©cole secondaire. LâintensitĂ© est
opĂ©rationnalisĂ© par le nombre dâheures de participation Ă des activitĂ©s parascolaires, alors que le
risque de dĂ©crochage est opĂ©rationnalisĂ© par le niveau dâengagement parental dans les activitĂ©s
touchant lâĂ©cole, les attitudes de lâĂ©lĂšve envers lâĂ©cole, sa perception de son niveau de rĂ©ussite
scolaire, ses aspirations scolaires et le niveau de supervision parentale. Durant deux années
consécutives, 2 094 adolescents (53 % de filles) de premiÚre à troisiÚme secondaire ont complété
le Logiciel de dépistage du décrochage scolaire (Fortin & Potvin, 2007), permettant de recueillir
lâensemble des donnĂ©es de la prĂ©sente Ă©tude. Dans les modĂšles testĂ©s, les rĂ©sultats indiquent que
ni les symptĂŽmes dĂ©pressifs, ni les problĂšmes de comportement extĂ©riorisĂ©s nâagissent Ă titre de
médiateurs sur la relation entre la participation à des activités parascolaires et le décrochage
scolaire. Or, les rĂ©sultats dĂ©montrent que lâintensitĂ© de la participation Ă des activitĂ©s
parascolaires prĂ©dit une diminution du risque de dĂ©crochage scolaire lâannĂ©e suivante. Ces
rĂ©sultats diffĂšrent cependant selon le genre des Ă©lĂšves et le type dâactivitĂ©s pratiquĂ©es.The goal of this study is to examine if depressive symptoms and behaviour problems are linked
to studentsâ degree of participation in extracurricular activities and their risk of dropping out of
high school. The degree to which students participate in extracurricular activities is measured by
the number of hours they spend in these activities. The risk of school dropout is measured by the
level of parental commitment in the activities regarding school, the attitudes of the youth toward
the school, their perception of their level of success at school, their school aspirations and the
level of parental supervision. During two consecutive years, 2,094 youth (53% of girls) from the
first to the third grades of secondary school (Grades 7 to 9 in USA) completed a survey with a
school dropout screening software (Logiciel de dépistage du décrochage scolaire - Fortin &
Potvin, 2007), which provided the data for the present study. In the tested models, the results
indicate that neither the depressive symptoms, nor the behaviour problems act as mediators on
the relation between participation in extracurricular activities and school dropout. Yet, the results
demonstrate that the intensity of participation in extracurricular activities predicts a decrease of
the risk of school dropout for the following year. These results differ, however, according to the
activity type and youthâs gende
The longitudinal association between externalizing and internalizing problems : an exploration of the Dual Failure Model
Abstract : The Dual Failure Model suggests that peer victimization (social failure) and academic difficulties (academic failure) mediate the association between externalizing and later internalizing problems. The present study sought to better understand why children with externalizing problems develop later internalizing problems by testing the Dual Failure Model using a sample of 744 children (aged 6 to 10 at Time 1 [T1]), of whom 434 (44.7% girls) presented with high levels of conduct problems at study inception. Both parent and teacher ratings of externalizing and internalizing problems support the social failure pathway, but not the academic failure pathway. Children with externalizing behaviors at T1 who developed internalizing problems 2 years later did so via their experiences of peer victimization. These results apply for both boys and girls and do not vary according to child age at T1 or the level of conduct problems at study inception. These findings underscore the importance of early screening and intervention for externalizing behavioral problems in order to reduce subsequent peer victimization and internalizing problems. Findings regarding the consequences of internalizing are also discussed
Plasma Ketone and Medium Chain Fatty Acid Response in Humans Consuming Different Medium Chain Triglycerides During a Metabolic Study Day
Background: Medium chain triglycerides (MCT) are ketogenic but the relationship between the change in plasma ketones and the change plasma medium chain fatty acids (MCFA)âoctanoate, decanoate, or dodecanoateâafter an oral dose of MCT is not well-known. An 8 h metabolic study day is a suitable model to assess the acute effects on plasma ketones and MCFA after a dose of tricaprylin (C8), tricaprin (C10), trilaurin (C12) or mixed MCT (C8C10).Objective: To assess in healthy humans the relationship between the change in plasma ketones, and octanoate, decanoate and dodecanoate in plasma total lipids during an 8 h metabolic study day in which a first 20 ml dose of the homogenized test oil is taken with breakfast and a second 20 ml dose is taken 4 h later without an accompanying meal.Results: The change in plasma acetoacetate, ÎČ-hydroxybutyrate and total ketones was highest after C8 (0.5 to 3 h post-dose) and was lower during tests in which octanoate was absent or was diluted by C10 in the test oil. The plasma ketone response was also about 2 fold higher without an accompanying meal (P = 0.012). However, except during the pure C10 test, the response of octanoate, decanoate or dodecanoate in plasma total lipids to the test oils was not affected by consuming an accompanying meal. Except with C12, the 4 h area-under-the-curve of plasma ÎČ-hydroxybutyrate/acetoacetate was 2â3 fold higher when no meal was consumed (P < 0.04).Conclusion: C8 was about three times more ketogenic than C10 and about six times more ketogenic than C12 under these acute metabolic test conditions, an effect related to the post-dose increase in octanoate in plasma total lipids
Cardiorenal ketone metabolism: a positron emission tomography study in healthy humans
Ketones are alternative energy substrates for the heart and kidney but no studies have investigated their metabolism simultaneously in both organs in humans. The present double tracer positron emission tomography (PET) study evaluated the organ distribution and basal kinetic rates of the radiolabeled ketone, 11C-acetoacetate (11C-AcAc), in the heart and kidney compared to 11C-acetate (11C-Ac), which is a well-validated metabolic radiotracer. Both tracers were highly metabolized by the left ventricle and the renal cortex. In the heart, kinetic rates were similar for both tracers. But in the renal cortex, uptake of 11C-Ac was higher compared to 11C-AcAc, while the reverse was observed for the clearance. Interestingly, infusion of 11C-AcAc led to a significantly delayed release of radioactivity in the renal medulla and pelvis, a phenomenon not observed with 11C-Ac. This suggests an equilibrium of 11C-AcAc with the other ketone, 11C-D-beta-hydroxybutyrate, and a different clearance profile. Overall, this suggests that in the kidney, the absorption and metabolism of 11C-AcAc is different compared to 11C-Ac. This dual tracer PET protocol provides the opportunity to explore the relative importance of ketone metabolism in cardiac and renal diseases, and to improve our mechanistic understanding of new metabolic interventions targeting these two organs
Non Mycobacterial Virulence Genes in the Genome of the Emerging Pathogen Mycobacterium abscessus
Mycobacterium abscessus is an emerging rapidly growing mycobacterium (RGM) causing a pseudotuberculous lung disease to which patients with cystic fibrosis (CF) are particularly susceptible. We report here its complete genome sequence. The genome of M. abscessus (CIP 104536T) consists of a 5,067,172-bp circular chromosome including 4920 predicted coding sequences (CDS), an 81-kb full-length prophage and 5 IS elements, and a 23-kb mercury resistance plasmid almost identical to pMM23 from Mycobacterium marinum. The chromosome encodes many virulence proteins and virulence protein families absent or present in only small numbers in the model RGM species Mycobacterium smegmatis. Many of these proteins are encoded by genes belonging to a âmycobacterialâ gene pool (e.g. PE and PPE proteins, MCE and YrbE proteins, lipoprotein LpqH precursors). However, many others (e.g. phospholipase C, MgtC, MsrA, ABC Fe(3+) transporter) appear to have been horizontally acquired from distantly related environmental bacteria with a high G+C content, mostly actinobacteria (e.g. Rhodococcus sp., Streptomyces sp.) and pseudomonads. We also identified several metabolic regions acquired from actinobacteria and pseudomonads (relating to phenazine biosynthesis, homogentisate catabolism, phenylacetic acid degradation, DNA degradation) not present in the M. smegmatis genome. Many of the ânon mycobacterialâ factors detected in M. abscessus are also present in two of the pathogens most frequently isolated from CF patients, Pseudomonas aeruginosa and Burkholderia cepacia. This study elucidates the genetic basis of the unique pathogenicity of M. abscessus among RGM, and raises the question of similar mechanisms of pathogenicity shared by unrelated organisms in CF patients
Links Between Metabolic and Structural Changes in the Brain of Cognitively Normal Older Adults: A 4-Year Longitudinal Follow-Up
We aimed to longitudinally assess the relationship between changing brain energy metabolism (glucose and acetoacetate) and cognition during healthy aging. Participants aged 71 ± 5 year underwent cognitive evaluation and quantitative positron emission tomography (PET) and magnetic resonance imaging (MRI) scans at baseline (N = 25) and two (N = 25) and four (N = 16) years later. During the follow-up, the rate constant for brain extraction of glucose (Kglc) declined by 6%â12% mainly in the temporo-parietal lobes and cingulate gyri (p †0.05), whereas brain acetoacetate extraction (Kacac) and utilization remained unchanged in all brain regions (p â„ 0.06). Over the 4 years, cognitive results remained within the normal age range but an age-related decline was observed in processing speed. Kglc in the caudate was directly related to performance on several cognitive tests (r = +0.41 to +0.43, allp †0.04). Peripheral insulin resistance assessed by the homeostasis model assessment of insulin resistance (HOMA-IR) was significantly inversely related to Kglc in the thalamus (r = â0.44, p = 0.04) and in the caudate (r = â0.43, p = 0.05), and also inversely related to executive function, attention and processing speed (r = â0.45 to â0.53, all p †0.03). We confirm in a longitudinal setting that the age-related decline in Kglc is directly associated with declining performance on some tests of cognition but does not significantly affect Kacac
Genetic diversity, linkage disequilibrium and power of a large grapevine (Vitis vinifera L) diversity panel newly designed for association studies
UMR-AGAP Equipe DAVV (DiversitĂ©, adaptation et amĂ©lioration de la vigne) ; Ă©quipe ID (IntĂ©gration de DonnĂ©es)International audienceAbstractBackgroundAs for many crops, new high-quality grapevine varieties requiring less pesticide and adapted to climate change are needed. In perennial species, breeding is a long process which can be speeded up by gaining knowledge about quantitative trait loci linked to agronomic traits variation. However, due to the long juvenile period of these species, establishing numerous highly recombinant populations for high resolution mapping is both costly and time-consuming. Genome wide association studies in germplasm panels is an alternative method of choice, since it allows identifying the main quantitative trait loci with high resolution by exploiting past recombination events between cultivars. Such studies require adequate panel design to represent most of the available genetic and phenotypic diversity. Assessing linkage disequilibrium extent and panel power is also needed to determine the marker density required for association studies.ResultsStarting from the largest grapevine collection worldwide maintained in Vassal (France), we designed a diversity panel of 279 cultivars with limited relatedness, reflecting the low structuration in three genetic pools resulting from different uses (table vs wine) and geographical origin (East vs West), and including the major founders of modern cultivars. With 20 simple sequence repeat markers and five quantitative traits, we showed that our panel adequately captured most of the genetic and phenotypic diversity existing within the entire Vassal collection. To assess linkage disequilibrium extent and panel power, we genotyped single nucleotide polymorphisms: 372 over four genomic regions and 129 distributed over the whole genome. Linkage disequilibrium, measured by correlation corrected for kinship, reached 0.2 for a physical distance between 9 and 458 Kb depending on genetic pool and genomic region, with varying size of linkage disequilibrium blocks. This panel achieved reasonable power to detect associations between traits with high broad-sense heritability (>â0.7) and causal loci with intermediate allelic frequency and strong effect (explainingâ>â10 % of total variance).ConclusionsOur association panel constitutes a new, highly valuable resource for genetic association studies in grapevine, and deserves dissemination to diverse field and greenhouse trials to gain more insight into the genetic control of many agronomic traits and their interaction with the environment
La stimulation de la cĂ©togenĂšse par la prise de diffĂ©rents supplĂ©ments alimentaires : carnitine, leucine, butyrate et monoglycĂ©ride dâoctanoate
Introduction : Un hypomĂ©tabolisme du glucose au cerveau peut apparaĂźtre des dĂ©cennies avant le diagnostic de maladie dâAlzheimer. Pourtant, le mĂ©tabolisme des cĂ©tones, le carburant alternatif principal au glucose, nâest pas altĂ©rĂ©, autant chez les personnes plus ĂągĂ©es que chez les personnes atteintes de la maladie dâAlzheimer. Les mĂ©thodes connues (diĂšte cĂ©togĂšne, jeĂ»ne, huile de triglycĂ©rides de moyennes chaĂźnes) pour augmenter la production de cĂ©tones comportent leurs inconvĂ©nients. Lâobjectif de ces projets Ă©tait de vĂ©rifier lâefficacitĂ© de produits commerciaux vendus Ă cet effet et dâĂ©valuer dâautres molĂ©cules qui pourraient ĂȘtre utilisĂ©es pour leur propriĂ©tĂ© cĂ©togĂšne. Ce sont des supplĂ©ments alimentaires pouvant servir de substrat pour la cĂ©togenĂšse (butyrate, monoglycĂ©ride dâoctanoate (O-MAG), leucine) ou de facilitateur du transport des acides gras (carnitine).
MĂ©thodes : Pour ce faire, les participants devaient se prĂ©senter au laboratoire pour plusieurs demi-journĂ©es dâĂ©tude dâune durĂ©e de 4 heures. Lors de ces journĂ©es, un des supplĂ©ments leur Ă©tait servi avec un dĂ©jeuner et des prises de sang Ă©taient effectuĂ©es toutes les 30 minutes. RĂ©sultats : Le produit commercial contenant des MCT, le butyrate, lâO-MAG et la leucine ont permis dâaugmenter respectivement les concentrations maximales en cĂ©tones plasmatiques de 568, 226, 67 et 70 ”mol/L (pâ€0,05) par rapport au contrĂŽle. De plus, la concentration plasmatique en octanoate Ă©tait corrĂ©lĂ©e significativement avec la concentration sanguine dâacĂ©toacĂ©tate (r=0,85 ; p <0,0001) et de ÎČ-hydroxybutyrate (r=0,58 ; p=0,01). Lâaire sous la courbe par gramme de produit ingĂ©rĂ© montre que le butyrate Ă©tait le supplĂ©ment cĂ©togĂšne le plus efficace et Ă©tait plus cĂ©togĂšne que le produit commercial, lâO-MAG et la leucine (p=0,009).
Discussion : Le butyrate Ă©tait 3 fois plus cĂ©togĂšne que tous les autres supplĂ©ments testĂ©s. Par contre, son ingestion a causĂ© quelques effets secondaires Ă certains participants. La leucine a Ă©tĂ© le seul supplĂ©ment Ă ne crĂ©er aucun inconfort chez les participants. Il faudrait donc Ă©tudier la possibilitĂ© de combiner plusieurs molĂ©cules dans un supplĂ©ment chimiquement pensĂ© pour ĂȘtre le plus efficace possible et pour ĂȘtre intĂ©ressant lors dâune utilisation quotidienne