25 research outputs found
Optimisation des conditions de culture des cellules endothéliales cornéennes félines pour la reconstruction d'un endothélium cornéen autologue
Les cellules endothĂ©liales cornĂ©ennes constituent un tissu Ă la fois extrĂȘmement particulier et d'une importance singuliĂšre. En effet, celui-ci est pourvu d'une capacitĂ© rĂ©gĂ©nĂ©ratrice pratiquement nulle, mais son intĂ©gritĂ© est essentielle Ă la transparence cornĂ©enne et donc Ă la vision. Par contre, l'endothĂ©lium cornĂ©en fait dĂ©faut dans diverses pathologies telles que la dystrophie de Fuch et la kĂ©ratopathie bulleuse du pseudophaque. La mĂ©thode traditionnelle pour le remplacement d'un endothĂ©lium cornĂ©en pathologique est la greffe de cornĂ©e pleine Ă©paisseur. Par contre, la greffe lamellaire postĂ©rieure est une alternative chirurgicale en plein essor, trĂšs intĂ©ressante, puisqu'elle permet de remplacer seulement la portion malade de la cornĂ©e. Cette technique chirurgicale a ouvert la porte Ă une nouvelle possibilitĂ© au niveau du gĂ©nie tissulaire. En effet, il est maintenant envisageable de greffer un endothĂ©lium produit en laboratoire. Un dĂ©fi supplĂ©mentaire, que s'est imposĂ© notre Ă©quipe, est de reconstruire non seulement un endothĂ©lium complet, mais d'en reconstruire un qui serait Ă©galement autologue, l'immunogĂ©nicitĂ© jouant un rĂŽle non nĂ©gligeable lors d'Ă©chec de greffes. Mon rĂŽle dans ce projet Ă©tait donc d'Ă©valuer la faisabilitĂ© de reconstruire par gĂ©nie tissulaire un endothĂ©lium cornĂ©en autologue pour notre modĂšle animal, et ce, Ă des fins de greffes. D'abord en optimisant les conditions de culture afin de permettre la croissance des cellules endothĂ©liales cornĂ©ennes animales. Puis en reconstruisant in vitro un endothĂ©lium Ă partir d'une biopsie cornĂ©enne de taille minimale. Un endothĂ©lium sain similaire au tissu natif a ainsi Ă©tĂ© reconstruit
IPV, distress, and affect dysregulation
Despite an increase in research initiatives and prevention campaigns, intimate partner violence
(IPV) remains a public health problem that affects many victims worldwide. The current study
aims to examine whether psychological distress symptoms (anger, depression, anxiety) are
indirectly related to the perpetration of IPV (physical assault, psychological abuse, coercive
control) through affect dysregulation (AD) in men seeking help. Online questionnaires assessing
psychological distress symptoms, AD, and violent behaviors were completed by 335 adult men
entering treatment for IPV. A path analysis model revealed the indirect associations between
psychological distress symptoms and higher IPV perpetration through higher AD. Symptoms of
anger were indirectly related to the three forms of perpetrated IPV through higher AD.
Symptoms of depression were, directly and indirectly, related to the three forms of perpetrated
IPV through higher AD. Finally, symptoms of anxiety were directly related to lower physical
assault perpetration, and indirectly related to higher physical assault and coercive control
perpetration through higher AD. The final model explained 10% of the variance in perpetrated
physical assault, 23% of the variance in perpetrated psychological abuse, and 13% of the
variance in perpetrated coercive control. These results underline the necessity of assessing and
addressing symptoms of psychological distress and AD among men perpetrators in the treatment
of IPV
Attachment, couple communication and sexual coercion
Abstract : The use of subtle strategies to have sex with an unwilling partner is harmful to a coupleâs sexual well-being but these strategies remain understudied. This research examined the mediating role of communication patterns in the associations between attachment insecurities and sustained sexual coercion in 145 same- and cross-gender couples, and the moderating role of partnersâ gender. In addition to actor and partner effects, results revealed significant indirect effects from attachment insecurities to sexual coercion via communication patterns, with moderating effects of gender. Results may help practitioners and researchers understand the ways attachment insecurities and dysfunctional communication patterns can manifest in the experience of subtle forms of sexual coercion within couples
Impact of cell source on human cornea reconstructed by tissue engineering
Purpose: To investigate the effect of the tissue origin of stromal fibroblasts and epithelial cells on reconstructed corneas in vitro.
Methods: Four types of constructs were produced by the self-assembly approach using the following combinations of human cells: corneal fibroblasts/corneal epithelial cells, corneal fibroblasts/skin epithelial cells, skin fibroblasts/corneal epithelial cells, skin fibroblasts/skin epithelial cells. Fibroblasts were cultured with ascorbic acid to produce stromal sheets on which epithelial cells were cultured. After 2 weeks at the air-liquid interface, the reconstructed tissues were photographed, absorption spectra were measured, and tissues were fixed for histologic analysis. Cytokine expression in corneal- or skin-fibroblast-conditioned media was determined with the use of protein array membranes. The effect of culturing reconstructed tissues with conditioned media, or media supplemented with a cytokine secreted mainly by corneal fibroblasts, was determined.
Results: The tissue source from which epithelial and mesenchymal cells were isolated had a great impact on the macroscopic and histologic features (epithelium thickness and differentiation) and the functional properties (transparency) of the reconstructed tissues. The reconstructed cornea had ultraviolet-absorption characteristics resembling those of native human cornea. The regulation of epithelial differentiation and thickness was mesenchyme-dependent and mediated by diffusible factors. IL-6, which is secreted in greater amounts by corneal fibroblasts than skin fibroblasts, decreased the expression of the differentiation marker DLK in the reconstructed epidermis.
Conclusions: The tissue origin of fibroblasts and epithelial cells plays a significant role in the properties of the reconstructed tissues. These human models are promising tools for gaining a thorough understanding of epithelial-stromal interactions and regulation of epithelia homeostasis
Reconstruction of a human cornea by the self-assembly approach of tissue engineering using the three native cell types
Purpose: The purpose of this study was to produce and characterize human tissue-engineered corneas reconstructed using
all three corneal cell types (epithelial, stromal, and endothelial cells) by the self-assembly approach.
Methods: Fibroblasts cultured in medium containing serum and ascorbic acid secreted their own extracellular matrix and
formed sheets that were superposed to reconstruct a stromal tissue. Endothelial and epithelial cells were seeded on each
side of the reconstructed stroma. After culturing at the air-liquid interface, the engineered corneas were fixed for histology
and transmission electron microscopy (TEM). Immunofluorescence labeling of epithelial keratins, basement membrane
components, Na+/K+-ATPase α1, and collagen type I was also performed.
Results: Epithelial and endothelial cells adhered to the reconstructed stroma. After 10 days at the air-liquid interface, the
corneal epithelial cells stratified (4 to 5 cell layers) and differentiated into well defined basal and wing cells that also
expressed Na+/K+-ATPase α1 protein, keratin 3/12, and basic keratins. Basal epithelial cells from the reconstructed
epithelium formed many hemidesmosomes and secreted a well defined basement membrane rich in laminin V and collagen
VII. Endothelial cells formed a monolayer of tightly-packed cells and also expressed the function related protein Na+/K
+-ATPase α1.
Conclusions: This study demonstrates the feasibility of producing a complete tissue-engineered human cornea, similar
to native corneas, using untransformed fibroblasts, epithelial and endothelial cells, without the need for exogenous
biomaterial
Internal deformation of the subducted Nazca slab inferred from seismic anisotropy
Within oceanic lithosphere a fossilized fabric is often preserved originating from the time of plate formation. Such fabric is thought to form at the mid-ocean ridge when olivine crystals align with the direction of plate spreading1, 2. It is unclear, however, whether this fossil fabric is preserved within slabs during subduction or overprinted by subduction-induced deformation. The alignment of olivine crystals, such as within fossil fabrics, can generate anisotropy that is sensed by passing seismic waves. Seismic anisotropy is therefore a useful tool for investigating the dynamics of subduction zones, but it has so far proved difficult to observe the anisotropic properties of the subducted slab itself. Here we analyse seismic anisotropy in the subducted Nazca slab beneath Peru and find that the fast direction of seismic wave propagation aligns with the contours of the slab. We use numerical modelling to simulate the olivine fabric created at the mid-ocean ridge, but find it is inconsistent with our observations of seismic anisotropy in the subducted Nazca slab. Instead we find that an orientation of the olivine crystal fast axes aligned parallel to the strike of the slab provides the best fit, consistent with along-strike extension induced by flattening of the slab during subduction (A. Kumar et al., manuscript in preparation). We conclude that the fossil fabric has been overprinted during subduction and that the Nazca slab must therefore be sufficiently weak to undergo internal deformation
Using gene expression to identify the most suitable environmental conditions for juvenile deepwater redfish (Sebastes mentella) growth and metabolism in the Estuary and the Gulf of St. Lawrence.
International audienceAbstract Deepwater redfish Sebastes mentella will be among the most important resource-sustaining commercial bottom-fish fisheries in the years to come in the Estuary and Gulf of St. Lawrence (EGSL). In 2011, 2012, and 2013, three strong cohorts were recruited to the stock; their abundance in 2018 was 80 times higher than that of the 1993â2012 period. The main goal of this work was to deepen our knowledge of their growth regulation and metabolism in order to identify molecular indicators and determine how they are influenced by natural environmental conditions. Fish weight and water temperature explained 11% of the variation in relative mRNA levels of specific gene targets in liver and muscle among seven sites where deepwater redfish were captured in the EGSL. The relative expression of liver insulin-like growth factor-1 (igf-1) and white muscle A-chain lactate dehydrogenase (ldh-a) correlate positively with weight, whereas heavy chain muscle myosin (myo), heart citrate synthase (cs), and white muscle pyruvate kinase (pk) correlate negatively. The relative expression of heart cytochrome c oxidase subunit 1 (cox-1) and white muscle igf-1 receptor isoform a (igf-1ra) correlate negatively with temperature. Deepwater redfish from the estuary were smaller than those caught at other sites. Since the growth potential of deepwater redfish was strongly correlated with temperature (being enhanced by higher temperatures), this study suggests an ecological advantage for this species in a climate-warming context
Décolonisation humanitaire et transformations structurelles
The present article outlines the internationalization strategy of the Center for International Studies and Cooperation (CECI) developed within the context of Canadian policy and international normative frameworks that call for the strengthening and empowerment of ecosystems. The results of this collaborative research, conducted using a mixed-methods methodology, reveal the organizational drivers and barriers within CECIâs transformation strategy. Our analysis, rooted in the work of critical humanitarian action authors within NGOs, enriches Permultterâs model by highlighting key transition moments during the implementation of CECIâs organizational strategy to decolonize its network
Regional variation of gene regulation associated with storage lipid metabolism in American glass eels (Anguilla rostrata)
Variation in gene regulation may be involved in the differences observed for life history traits within species. American eel (Anguilla rostrata) is well known to harbor distinct ecotypes within a single panmictic population. We examined the expression of genes involved in the regulation of appetite as well as lipid and glycogen among glass eels migrating to different locations on the Canadian east coast and captured at two different periods of upstream migration. Gene expression levels of three reference and five candidate genes were analyzed by real-time PCR with Taqman probes in recently captured wild glass eels. All gene transcripts were detected in glass eels. Of the five candidate genes, bile salt activated and triacylglycerol lipases were respectively 7.65 and 3.25 times more expressed in glass eels from the St. Lawrence estuary than in those from Nova Scotia, and there was no effect related to the two-week difference in capture date. These two genes explained 82.41% of the dissimilarity between the two rivers. In contrast, glycogen phosphorylase, ghrelin, and leptin receptor genes showed no significant differences in gene transcription. These results confirmed at the molecular level an observation that was recently made at the phenotypic level that glass eels from the St. Lawrence estuary have a greater capacity to use lipid reserves to sustain their metabolic needs. These observations add to the body of evidence supporting the hypothesis that regional phenotypic variation observed in American eel is determined early in life and that part of this variation is likely under genetic control. -- Keywords : Ecotypes ; Ghrelin ; Glycogen phosphorylase ; Leptin receptor ; Lipase ; mRNA expression ; Transcriptomics