Pour savoir comment effectuer et gérer un dépôt de document, consultez le « Guide abrégé – Dépôt de documents » sur le site Web de la Bibliothèque. Pour toute question, écrivez à corpus@ulaval.ca.
 

Personne :
Xu, Isabelle

En cours de chargement...
Photo de profil

Adresse électronique

Date de naissance

Projets de recherche

Structures organisationnelles

Fonction

Nom de famille

Xu

Prénom

Isabelle

Affiliation

Université Laval. Faculté de médecine

ISNI

ORCID

Identifiant Canadiana

ncf11901209

person.page.name

Résultats de recherche

Voici les éléments 1 - 3 sur 3
  • PublicationAccès libre
    Change in the natural head-neck orientation momentarily altered sensorimotor control during sensory transition
    (2017-01-17) Simoneau, Martin; Teasdale, Normand; Laurendeau, Simon; Xu, Isabelle
    Achilles tendon vibration generates proprioceptive information that is incongruent with the actual body position; it alters the perception of body orientation leading to a vibration-induced postural response. When a person is standing freely, vibration of the Achilles tendon shifts the internal representation of the verticality backward thus the vibration-induced postural response realigned the whole body orientation with the shifted subjective vertical. Because utricular otoliths information participates in the creation of the internal representation of the verticality, changing the natural orientation of the head-neck system during Achilles tendon vibration could alter the internal representation of the earth vertical to a greater extent. Consequently, it was hypothesized that compared to neutral head-neck orientation, alteration in the head-neck orientation should impair balance control immediately after Achilles tendon vibration onset or offset (i.e., sensory transition) as accurate perception of the earth vertical is required. Results revealed that balance control impairment was observed only immediately following Achilles tendon vibration offset; both groups with the head-neck either extended or flexed showed larger body sway (i.e., larger root mean square scalar distance between the center of pressure and center of gravity) compared to the group with the neutral head-neck orientation. The fact that balance control was uninfluenced by head-neck orientation immediately following vibration onset suggests the error signal needs to accumulate to a certain threshold before the internal representation of the earth vertical becomes incorrect.
  • PublicationRestreint
    Matrix metalloproteinases and their inhibitors in Fuchs endothelial corneal dystrophy
    (Academic Press, 2021-02-19) Xu, Isabelle; Thériault, Mathieu; Brunette, Isabelle; Rochette, Patrick J.; Proulx, Stéphanie
    Fuchs endothelial corneal dystrophy (FECD) is characterized by a progressive loss of corneal endothelial cells (CECs) and an abnormal accumulation of extracellular matrix in Descemet’s membrane leading to increased thickness and formation of excrescences called guttae. Extracellular matrix homeostasis is modulated by an equilibrium between matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors (TIMPs). This study aimed to investigate MMPs and TIMPs profile in FECD, taking into account cell morphology. Populations of FECD and healthy CECs were cultured and their conditioned media collected for analysis. The presence of proteases in the conditioned media was studied using a semi-quantitative proteome profiler array, and MMPs levels were assessed using quantitative assays (ELISA and quantitative antibody array). MMP activity was determined by zymography and fluorometry. The expression pattern of the membrane type 1-MMP (MT1-MMP, also known as MMP-14) was examined by immunofluorescence on ex vivo FECD and healthy explants of CECs attached to Descemet’s membrane. Finally, MMPs and TIMPs protein expression was compared to gene expression obtained from previously collected data. FECD and healthy CEC populations generated cultures of endothelial, intermediate, and fibroblastic-like morphology. Various MMPs (MMP-1, -2, -3, -7, -8, -9, -10, and -12) and TIMPs (TIMP-1 to -4) were detected in both FECD and healthy CECs culture supernatants. Quantitative assays revealed a decrease in MMP-2 and MMP-10 among FECD samples. Both these MMPs can degrade the main extracellular matrix components forming guttae (fibronectin, laminin, collagen IV). Moreover, MMPs/TIMPs ratio was also decreased among FECD cell populations. Activity assays showed greater MMPs/Pro-MMPs proportions for MMP-2 and MMP-10 in FECD cell populations, although overall activities were similar. Moreover, the analysis according to cell morphology revealed among healthy CECs, both increased (MMP-3 and -13) and decreased (MMP-1, -9, -10, and -12) MMPs proteins along with increased MMPs activity (MMP-2, -3, -9, and -10) in the fibroblastic-like subgroup when compared to the endothelial subgroup. However, FECD CECs did not show similar behaviors between the different morphology subgroups. Immunostaining of MT1-MMP on ex vivo FECD and healthy explants revealed a redistribution of MT1-MMP around guttae in FECD explants. At the transcriptional level, no statistically significant differences were detected, but cultured FECD cells had a 12.2-fold increase in MMP1 and a 4.7-fold increase in TIMP3. These results collectively indicate different, and perhaps pathological, MMPs and TIMPs profile in FECD CECs compared to healthy CECs. This is an important finding suggesting the implication of MMPs and TIMPs in FECD pathophysiology.