Les villes moyennes. Analyse démographique et économique, 1971-2001 : Note de recherche

Les villes moyennes supérieures (VMS) au Québec sont au nombre de quatre. Il s’agit de Gatineau, Sherbrooke, Saguenay et Trois-Rivières. Elles se distinguent des autres villes moyennes par leur population plus importante, leur base économique plus solide et plus diversifiée et leur fonction de capitale administrative dans leur région respective. Aucune de ces villes ne se situe à la périphérie immédiate des grandes agglomérations urbaines de Montréal et de Québec et en ce sens, elles ne constituent pas des villes satellites. L’analyse de leur évolution démographique et économique pour la période 1971 – 2001 révèle que, dans l’ordre, ce sont les villes de Gatineau et Sherbrooke qui ont connu la meilleure croissance et qui ont les meilleures perspectives d’avenir ; que la ville de Trois-Rivières connaît depuis les années 1990 une stabilité précaire, et que la ville de Saguenay est engagée depuis la dernière décennie dans une relative phase de déclin. Le poids total de ces quatre VMS dans l’économie et la démographie québécoises, s’avère relativement faible ; néanmoins, elles seront sûrement au centre des politiques publiques visant le développement des régions administratives où elles occupent le rôle de pôle régional.There are four larger medium-sized cities in Québec, namely Gatineau, Sherbrooke, Saguenay and Trois-Rivières. They are distinguished from the other medium-sized cities by larger populations, a more solid and diversified economic base, and their function as administrative capitals of their respective regions. None of these cities are located on the immediate outskirts of the major metropolitan areas of Montréal or Québec City, and in this sense they do not constitute satellite cities. An analysis of their demographic and economic trends during the period 1971-2001 reveals that it is the cities of Gatineau and Sherbrooke, in that order, that have enjoyed the strongest growth and that have the best outlook for the future ; since the 1990s, Trois-Rivières has been in a state of stagnation, while Saguenay has been in a phase of relative decline over the past decade. The overall weight of these four larger medium-sized cities in Québec’s economy and demographic profile is relatively small ; nevertheless, they will certainly be at the focus of public policies aiming toward the development of the administrative regions in which they play the role of regional hubs

Adherens junction proteins are expressed in collagen corneal equivalents produced in vitro with human cells

Purpose To test whether adherens junction proteins are present in the epithelium and the endothelium of corneal equivalents. Methods Corneal cell types were harvested from human eyes and grown separately. Stromal equivalents were constructed by seeding fibroblasts into a collagen gel on which epithelial and endothelial cells were added on each side. Alternatively, bovine endothelial cells were used. At maturity, sections of stromal equivalents were processed for Masson's trichrome or indirect immunofluorescence using antibodies against pan-, N-, or E-cadherins or a- or ß-catenins. Alternatively, stromal equivalents were dissected, to separate the proteins from the epithelium, endothelium, and stroma with sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Western blots of the transferred proteins exposed to these primary antibodies were detected with chemiluminescence. Native corneas were processed similarly. Results Three or four layers of epithelial cells reminiscent of the native cornea (basal cuboidal and superficial flatter cells) lay over a stromal construct containing fibroblastic cells under which an endothelium is present. Western blots and indirect immunofluorescence revealed that, similarly to the native cornea, the epithelium reacted positively to antibodies against catenins (a and ß) and E-cadherin. The endothelium of corneal constructs, whether of human or bovine origin, reacted mildly to catenins and N-cadherin. Conclusions This collagen-based corneal equivalent simulated the native cornea. Cells from the epithelial and endothelial layers expressed adherens junction proteins, indicating the presence of cell–cell contacts and the existence of polarized morphology of these layers over corneal equivalents

Export processing zones and global class formation

Anthropologists are renown for studying small places. Even though the discipline’s focus has extended well beyond the remote and fairly self-contained villages that were its characteristic subject matter through most of the twentieth century, a concern with the local remains an important part of the way that anthropologists approach the world. This orientation brings benefits to anthropologists and to those who study their works, but it also brings costs. In particular, that concern with the local often diverts attention from the broader frame that encompasses the locality. Even anthropologists who have studied the local in terms of that frame commonly focus on the relationship between the local and the frame, rather than seeing the frame as part of their understanding of those small places (e.g. Comaroff and Comaroff 2001; Ong 2006). Equally, that concern often is accompanied by an inattention to things that are not apparent from the local perspective. So, a focus on the local can accommodate slum dwellers in Mumbai or workers in a Bangalore call center, but not the places where their broader frame is shaped, such as a working group within the World Bank or a conference attracting international investors. As a result, anthropological descriptions and analyses of these small places commonly are partial, or even flawed, as they omit important factors affecting the local

Influence of Sp1/Sp3 expression on corneal epithelial cells proliferation and differentiation properties in reconstructed tissues

PURPOSE : Primary cultured epithelial cells are widely used for the production of tissue-engineered substitutes and are gaining popularity as a model for gene expression studies. However, as such cells are passaged in culture, they often lose their ability to proliferate by progressing toward terminal cell differentiation, a process likely to be determined by altered expression of transcription factors that have functions critical for cell adhesion and differentiation. This study was designed to determine whether the variable life span of primary cultured human corneal epithelial cells (HCECs) might be the consequence of varying expression levels of the well-known transcription factors Sp1 and Sp3 (Sp1/Sp3). METHODS : HCECs were obtained from donor eyes and cultured on irradiated Swiss-3T3. Sp1/Sp3 expression was monitored by Western blot and electrophoretic mobility shift assay (EMSA). The Sp1/Sp3 regulatory influence was evaluated by transfection of HCECs with a recombinant plasmid bearing the Sp1/Sp3-dependent poly(ADP-ribose) polymerase (rPARP) promoter fused to the CAT reporter gene. HCECs that expressed various levels of Sp1/Sp3 were also used for the production of corneal substitutes. RESULTS : Expression of Sp1/Sp3 was dramatically inconsistent between HCECs isolated from the eyes of different donors. Both factors were highly expressed during one passage and then totally disappeared as cells terminally differentiated. Proper stratification of HCECs on reconstructed tissue substitutes could be obtained only with cells that also had a delayed peak of Sp1/Sp3 expression when cultured in vitro. CONCLUSIONS : Expression of Sp1/Sp3 may represent a good predictor for selecting HCECs that are most likely to proliferate, stratify, and differentiate properly when used for the production of reconstructed corneal substitutes

Transcriptional regulation of the human α6 integrin gene by the transcription factor NFI during corneal wound healing

Purpose. Wound healing of the corneal epithelium is highly influenced by regulation of integrin gene expression. A recent study demonstrated that laminin (LM), a major constituent of the extracellular matrix (ECM), reduces expression of the human α6 integrin subunit gene by altering the properties of the transcription factor (TF) Sp1. In this work, a target site was identified for the TF nuclear factor I (NFI) on the human α6 gene, and its regulatory influence was characterized in corneal epithelial cells. Methods. Plasmids bearing the α6 promoter fused to the CAT gene were transfected into human (HCECs) and rabbit (RCECs) corneal epithelial cells grown on LM. The DNA-binding site for NFI in the α6 promoter was identified by DNase I footprinting. Expression and DNA binding of NFI was monitored by Western blot, RT-PCR, and electrophoretic mobility shift assays (EMSAs), and its function was investigated through RNAi and NFI overexpression assays. Results. All NFI isoforms were found to be expressed in HCECs and RCECs. Transfection analyses revealed that NFI is a repressor of α6 expression in both types of cells. LM increases expression of NFI, whereas inhibition of each NFI isoform increases promoter activity suggesting that NFI is a key repressor of α6 transcription. In addition, the negative influence of NFI appears to be potentiated by the degradation of Sp1 when cells are grown on LM. Conclusions. Repression of α6 expression therefore contributes to the final steps of corneal wound healing by both reducing proliferation and allowing attachment of the epithelium to the basal membrane

Autologous transplantation of rabbit limbal epithelia cultured on fibrin gels for ocular surface reconstruction

Purpose: Regeneration of the corneal epithelium could be severely impaired in patients suffering from limbal stem cell deficiency. The purpose of this study was to evaluate the restoration of the corneal epithelium by grafting onto denuded corneas autologous limbal cells cultured on fibrin gels. The rabbit model was chosen to allow the microscopic evaluation over time after grafting. Methods: Rabbit limbal epithelial cells (RLECs) were isolated and cultured from small limbal biopsies (3 mm2 ). The epithelium was separated from stroma after dispase digestion and put in culture on lethally irradiated fibroblasts used as a feeder layer. At the first passage, RLECs were cultured on a fibrin gel matrix. At confluence, the cultured epithelia were grafted in vivo on denuded autologous rabbit corneas. At different postoperative times, grafted and control (without graft or grafted with fibrin gels only) rabbit corneas were compared in vivo with a slit lamp microscope, and in situ by histological and immunohistological microscopy of harvested biopsies. Results: A small limbal biopsy was sufficient to generate enough RLECs to prepare several grafts and to perform cell analysis. Only two weeks were required to produce a cultured epithelium suitable for autologous transplantation. One month after grafting, a normal corneal phenotype was observed on the ocular surface of grafted rabbits in contrast to the control rabbits (ungrafted or grafted with fibrin gel only) where histological signs of conjunctivalization were found. The absence of goblet cells and negative staining for keratin 4 confirmed that the cultured cells persisted and that the epithelium regenerated after grafting was not from conjunctival origin. Conclusions: Our results demonstrate that an autologous epithelium cultured on a physiologically biodegradable matrix can be prepared from a small biopsy and grafted on denuded cornea. The autologous graft allows epithelial regeneration from cultured cells and promotes corneal healing of unilateral total stem cell deficiency

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