7 research outputs found
Physiopathologie du somnambulisme : Ă©tude de lâactivitĂ© cĂ©rĂ©brale en sommeil lent profond via la Tomographie dâĂmission Monophotonique (TEMP) et l'analyse de connectivitĂ© fonctionnelle cĂ©rĂ©brale
Le somnambulisme se caractĂ©rise par des comportements moteurs complexes au cours du sommeil, dans un Ă©tat oĂč persiste une altĂ©ration des fonctions cognitives, du jugement et de la conscience. Bien que cette parasomnie affecte jusquâĂ 4% des adultes, sa physiopathologie demeure peu documentĂ©e Ă ce jour. ConceptualisĂ© au dĂ©part comme un trouble reflĂ©tant une transition incomplĂšte du sommeil vers lâĂ©veil, le somnambulisme est maintenant aussi considĂ©rĂ© comme un trouble reflĂ©tant des anomalies au niveau du sommeil lent profond (SLP). Lâobjectif de la thĂšse est de documenter la physiopathologie du trouble Ă la lumiĂšre de ces conceptualisations, en caractĂ©risant lâactivitĂ© cĂ©rĂ©brale de somnambules Ă lâĂ©veil et en sommeil lent profond Ă lâaide de deux techniques novatrices : les analyses de connectivitĂ© fonctionnelle cĂ©rĂ©brale et la tomographie par Ă©mission monophotonique. Ces deux techniques sont particuliĂšrement indiquĂ©es pour lâĂ©tude du sommeil et, bien que largement utilisĂ©es pour dĂ©crire le sommeil rĂ©gulier, celles-ci nâavaient jamais encore Ă©tĂ© utilisĂ©es pour dĂ©crire le SLP de somnambules.
Dans une premiĂšre Ă©tude, des analyses de connectivitĂ© fonctionnelle cĂ©rĂ©brale ont permis dâinvestiguer les changements dâinterdĂ©pendance et de synchronisation des signaux EEG de 27 somnambules. La pĂ©riode de 20 secondes immĂ©diatement avant le dĂ©clenchement dâun Ă©pisode de somnambulisme a Ă©tĂ© comparĂ©e Ă la pĂ©riode survenant 2 minutes avant leur dĂ©clenchement. Les rĂ©sultats montrent que les Ă©pisodes sont prĂ©cĂ©dĂ©s par des changements dans la connectivitĂ© fonctionnelle cĂ©rĂ©brale qui suggĂšrent le passage vers un Ă©tat plus prĂšs de lâĂ©veil: une diminution de la connectivitĂ© locale dans la bande delta, caractĂ©ristique du sommeil, ainsi quâune augmentation de la connectivitĂ© dans la bande beta, caractĂ©ristique de lâĂ©veil, sur de longs rĂ©seaux inter-hĂ©misphĂ©riques impliquant les rĂ©gions frontales, pariĂ©tales et occipitales. Ces rĂ©sultats soulignent que la coexistence entre le sommeil et lâĂ©veil qui sous-tend les Ă©pisodes se manifeste Ă©galement sous forme de changements au niveau des rĂ©seaux de connectivitĂ© cĂ©rĂ©brale et que des marqueurs de cette coexistence sâinstallent avant mĂȘme les manifestations comportementales des Ă©pisodes. Cette coexistence suggĂ©rant des anomalies du processus de transition vers lâĂ©veil, elle appuie par ailleurs la classification du somnambulisme dans la catĂ©gorie des troubles de lâĂ©veil.
Dans une deuxiĂšme Ă©tude, la tomographie par Ă©mission monophotonique a Ă©tĂ© utilisĂ©e afin de caractĂ©riser le SLP et lâĂ©veil, suivant 24 heures de privation de sommeil, de 10 somnambules et 10 participants contrĂŽles. Les rĂ©sultats rĂ©vĂšlent que les somnambules, lorsque comparĂ©s aux participants contrĂŽles, montrent une diminution de la perfusion en SLP dans plusieurs rĂ©gions frontales et pariĂ©tales, rĂ©gions qui ont prĂ©alablement Ă©tĂ© associĂ©es Ă la gĂ©nĂ©ration du SLP et Ă lâoccurrence dâĂ©pisodes. De plus, les rĂ©sultats en SLP montrent une diminution de la perfusion dans le cortex prĂ©frontal dorsolatĂ©ral et lâinsula, ce qui est congruent avec des manifestations cliniques des Ă©pisodes. Ă lâĂ©veil, une diminution de la perfusion est observĂ©e chez les somnambules dans plusieurs rĂ©gions frontales et pariĂ©tales, ce qui peut ĂȘtre mis en lien avec les dysfonctions cognitives et fonctionnelles diurnes observĂ©es chez cette population.
En rĂ©sumĂ©, cette thĂšse suggĂšre que le somnambulisme est associĂ© Ă des anomalies fonctionnelles cĂ©rĂ©brales qui sâĂ©tendent au-delĂ des Ă©pisodes eux-mĂȘmes, affectant la pĂ©riode prĂ©cĂ©dant leur dĂ©clenchement, de mĂȘme que le SLP et lâĂ©veil suivant privation de sommeil. Ainsi, elle souligne lâimportance dâen arriver Ă une comprĂ©hension de la physiopathologie du somnambulisme qui prenne en considĂ©ration la façon dont ce trouble se manifeste en dehors des Ă©pisodes comportementaux.Somnambulism is characterized by the occurrence of complex motor behaviours during NREM sleep in a state in which consciousness, judgement and cognitive functions are altered. Although the disorder affects up to 4% of adults, its pathophysiology remains poorly understood. Initially viewed as a disorder reflecting an incomplete transition from sleep to wakefulness, sleepwalking is now also conceptualized as reflecting key anomalies in slow-wave sleep. The main objective of this thesis was to characterize the cerebral activity of sleepwalkers during wakefulness and during slow-wave sleep in order to elucidate the nature of episode occurrence as well as the disorderâs pathophysiology. EEG functional connectivity analysis and single-photon emission computed tomography (SPECT) are two innovative methods that have been widely used to describe normal sleep. However, these methods had not yet been used to investigate sleepwalkersâ slow wave sleep.
In study 1, EEG functional connectivity analyses were used to investigate changes in EEG signal synchronization and interdependency in a group of 27 sleepwalkers who experienced a somnambulistic episode during slow-wave sleep. The 20-sec segment of sleep EEG immediately preceding each patientâs episode was compared with the 20-sec segment occurring two minutes prior to episode onset. Results show that episode onset is preceded by changes in EEG functional connectivity, including decreased delta connectivity in parietal and occipital regions and increased beta connectivity in symmetric inter-hemispheric networks implicating frontal, parietal and occipital areas. These results indicate that somnambulistic episodes are preceded by brain processes characterized by the co-existence of arousal and deep sleep and provide new insights into sleepwalkingâs pathophysiology while bolstering its conceptualization as a disorder of arousal.
In study 2, SPECT was used to investigate recovery slow-wave sleep and wakefulness following sleep deprivation in 10 sleepwalkers and 10 matched controls. When compared to controls, sleepwalkers showed decreased rCBF in frontal and parietal areas, regions previously associated with slow-wave sleep generation and episode occurrence. Additionally, reduced rCBF was found in the dorsolateral prefrontal cortex and insula during recovery slow-wave sleep, which is consistent with several clinical features of somnambulistic episodes. Reduced rCBF found during sleepwalkersâ resting-state wakefulness in frontal and parietal regions may be related to daytime cognitive and functional anomalies previously described in this population.
Taken as a whole, the results from this thesis suggest that sleepwalking is characterized by cerebral functional anomalies that extend well beyond the episodes themselves. In fact, not only are such anomalies observed immediately preceding episode onset, but also more generally during sleepwalkersâ recovery slow-wave sleep and resting-state wakefulness following sleep deprivation. These findings highlight the importance of conceptualizing sleepwalkingâs pathophysiology in a way that adequately accounts for how the disorder manifests itself outside of actual behavioural episodes
Hérédité et longévité au Québec ancien
Par lâentremise du Registre de la population du QuĂ©bec ancien (RPQA), banque de donnĂ©es Ă©laborĂ©e dans le cadre du Programme de recherche en dĂ©mographie historique, nous avons observĂ© lâexistence dâune composante familiale de la longĂ©vitĂ©. En effet, lâĂąge au dĂ©cĂšs des parents semble influencer lâĂąge au dĂ©cĂšs de leurs fils et filles, particuliĂšrement pour les parents dĂ©cĂ©dĂ©s aprĂšs 70 ans. Nous avons aussi observĂ© une convergence significative de lâĂąge au dĂ©cĂšs dans les fratries. Cependant, il existe Ă©galement une relation entre les Ăąges au dĂ©cĂšs des conjoints, ce qui laisse supposer que la composante familiale est due Ă la part environnementale de lâhĂ©ritabilitĂ© plutĂŽt quâĂ la part gĂ©nĂ©tique.For a long time, people have had a belief in a form of heritability in regard to longevity. According to this belief, reaching very great ages would be specific to some families. By using the Registre de la population du QuĂ©bec ancien (RPQA), a database put together by the Programme de recherche en dĂ©mographie historique (PRDH), we have established the existence of a familial component of human longevity. Indeed, our results suggest that the parentsâ ages at death could have had a significant influence on their childrenâs ages at death, particularly for parents who died at age 70 or over. Moreover, our analysis revealed a significant association between brothersâ and sistersâ ages at death. However, there is also a clear relationship between spousesâ ages at death, which implies that the familial component of longevity could be more strongly related to the environmental component of heritability than to its genetic component
EEG functional connectivity prior to sleepwalking : evidence of interplay between sleep and wakefulness
Study Objectives: Although sleepwalking (somnambulism) affects up to 4% of adults, its pathophysiology remains poorly understood. Sleepwalking can be
preceded by fluctuations in slow-wave sleep EEG signals, but the significance of these pre-episode changes remains unknown and methods based on EEG
functional connectivity have yet to be used to better comprehend the disorder.
Methods: We investigated the sleep EEG of 27 adult sleepwalkers (mean age: 29 ± 7.6 years) who experienced a somnambulistic episode during slow-wave
sleep. The 20-second segment of sleep EEG immediately preceding each patientâs episode was compared with the 20-second segment occurring 2 minutes
prior to episode onset.
Results: Results from spectral analyses revealed increased delta and theta spectral power in the 20 seconds preceding the episodesâ onset as compared to
the 20 seconds occurring 2 minutes before the episodes. The imaginary part of the coherence immediately prior to episode onset revealed (1) decreased delta
EEG functional connectivity in parietal and occipital regions, (2) increased alpha connectivity over a fronto-parietal network, and (3) increased beta connectivity
involving symmetric inter-hemispheric networks implicating frontotemporal, parietal and occipital areas.
Conclusions: Taken together, these modifications in EEG functional connectivity suggest that somnambulistic episodes are preceded by brain processes
characterized by the co-existence of arousal and deep slee
A mutation in the methionine aminopeptidase gene provides phage resistance in Streptococcus thermophilus
Streptococcus thermophilus is a lactic acid bacterium widely used by the dairy industry for the
manufacture of yogurt and specialty cheeses. It is also a Gram-positive bacterial model to study phagehost interactions. CRISPR-Cas systems are one of the most prevalent phage resistance mechanisms in
S. thermophilus. Little information is available about other host factors involved in phage replication
in this food-grade streptococcal species. We used the model strain S. thermophilus SMQ-301 and its
virulent phage DT1, harboring the anti-CRISPR protein AcrIIA6, to show that a host gene coding for
a methionine aminopeptidase (metAP) is necessary for phage DT1 to complete its lytic cycle. A single
mutation in metAP provides S. thermophilus SMQ-301 with strong resistance against phage DT1. The
mutation impedes a late step of the lytic cycle since phage adsorption, DNA replication, and protein
expression were not afected. When the mutated strain was complemented with the wild-type version
of the gene, the phage sensitivity phenotype was restored. When this mutation was introduced into
other S. thermophilus strains it provided resistance against cos-type (Sf21dt1virus genus) phages but
replication of pac-type (Sf11 virus genus) phages was not afected. The mutation in the gene coding for
the MetAP induces amino acid change in a catalytic domain conserved across many bacterial species.
Introducing the same mutation in Streptococcus mutans also provided a phage resistance phenotype,
suggesting the wide-ranging importance of the host methionine aminopeptidase in phage replication
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