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G Lauzon

Publications and source records attributed to G Lauzon.

8 recordsLinked to original sources
PubMed1998

Plakoglobin induces desmosome formation and epidermoid phenotype in N-cadherin-expressing squamous carcinoma cells deficient in plakoglobin and E-cadherin.

Pg is a homologue of beta-catenin and Armadillo, the product of the Drosophila segment polarity gene and has been shown to have both adhesive and signaling functions. It interacts with both classic and desmosomal cadherins. Pg interaction with the desmosomal cadherins is essential for desmosome assembly. Its precise role in the classic cadherin complexes is unclear, although Pg-E-cadherin interaction appears to be necessary for the formation of desmosomes. In addition to cadherins in adhesion complexes, Pg interacts with a number of proteins involved in regulation of cell differentiation and proliferation such as Lef-1/Tcf-1 transcription factors and the tumor suppressor protein APC. In this study, we have introduced Pg cDNA into SCC9 cells, a Pg- and E-cadherin-deficient squamous cell carcinoma line, which also lacks desmosomes. These cells have both alpha-catenin and beta-catenin, display unusual expression of N-cadherin, and have the typical fibroblastic phenotype of transformed cells. Pg-expressing SCC9 cells (SCC9P) formed desmosomes. Desmosome formation coincided with the appearance of an epidermoid phenotype, with increased adhesiveness and a contact-dependent decrease in growth. Biochemical characterization of SCC9P cells showed an increase in the expression and stability of N-cadherin and a decrease in level and stability of beta-catenin, without any apparent effects on alpha-catenin. These results show that, in the absence of E-cadherin, Pg can efficiently use N-cadherin to induce desmosome formation and epidermoid phenotype. They also suggest a role for Pg as one of the regulators of the intracellular beta-catenin levels and underscore the pivotal role of this protein in regulating cell adhesion and differentiation.

Cadherins↗
PubMed1998

L-CAM expression induces fibroblast-epidermoid transition in squamous carcinoma cells and down-regulates the endogenous N-cadherin.

SCC9 cells, derived from a squamous carcinoma of the tongue, were shown to lack E-cadherin but express alpha- and beta-catenins and N-cadherin. These cells also lack plakoglobin expression, do not assemble desmosomes and exhibit the typical morphology and growth properties of transformed cells. The N-cadherin expressed in SCC9 cells has properties similar to other classical cadherins, including interactions with the catenins. We transfected SCC9 cells with a full-length cDNA for L-CAM (liver cell adhesion molecule), the functional chicken homologue of E-cadherin. The exogenously expressed L-CAM formed complexes with catenins and the cytoskeleton and induced a morphological transition from fibroblastoid to epithelioid, conferred density-dependent growth inhibition, increased aggregation ability, and increased synthesis and stability of alpha- and beta-catenins. Coincident with these phenotypic changes, we detected a significant reduction in the level of endogenous N-cadherin, primarily as a result of rapid degradation of this protein in L-CAM-expressing cells. These results show the abnormal expression of N-cadherin in these transformed epidermoid cells, demonstrate the dynamics of the relationship between two cadherins, and provide a model system for the functional analysis of the tumor suppressor activity of E-cadherin in carcinomas.

Cadherins↗
PubMed1992

Positive withdrawal and the quest for meaning: the reconstruction of experience among schizophrenics.

Psychosocial rehabilitation often remains entrapped within a restrictive definition. It is characterized by a normative orientation, which predetermines the objectives to achieve, and by an approach from outside of the person, which emphasizes the functional aspects of rehabilitation. In this context, marks of withdrawal, lack of involvement, or inactivity are interpreted as signs of passivity or as residual or negative symptoms, which are often associated with a negative prognosis. In parallel, as data regarding the heterogeneity of evolution of schizophrenia begin to accumulate, some authors have defended the idea that studies have to concentrate on the course of the disorder and on the associated processes (Harding et al. 1987; Strauss 1986). They propose going beyond an objective evaluation of signs and behaviors in order to situate them within a larger life-frame. This draws attention to the potential polysemy of symptoms, including the so-called negative symptoms, which can reflect a diversity of influences and therefore possess various psychiatric meanings (Strauss 1989). Yet, the systematic study of "meaning" in psychiatry is still in its infancy and lacks clear conceptual and methodological points of reference (Strauss and Estroff 1989). On another hand, implications for rehabilitation of a meaning-centered approach to psychiatric symptoms have not been fully elaborated. An intensive study conducted in Montreal with patients diagnosed as schizophrenics sought to describe the factors and processes associated with different types of insertion in the community, and particularly to understand the rehabilitative strategies and the specific forms of being-in-the-world associated with an ability to remain in the community. Data collected through open-ended interviews were both quantitatively analyzed and subjected to content and qualitative analysis. The conceptual reference frame was derived from anthropology and from the European school of psychiatric phenomenology. Data indicate that non-rehospitalization is associated with a stance of "positive withdrawal" (Corin 1990); it is characterized by a position at a distance from social roles and social relationships, combined with various strategies for keeping more tenuous links with the social environment. The case study presented here illustrates the complex organization of these various elements in a given life-frame. It also demonstrates the role played by symbols and meanings in developing a new articulation of personal experience.

Activities of Daily Living↗
PubMed1988

[Realities and mirages : psychic and social spaces of reintegration.].

This study, based on a sampling of people who were diagnosed schizophrenic, sought to describe the different types of positive and negative social réintégration. Research combined an anthropological approach with rigid discipline in the gathering of data. The authors examined réintégration from three points of view : social relations, social roles, and utilization of space and time (l'espace-temps). Data shows that people who are constantly rehospitalized feel marginalized and experience rejection, particularly with family and relatives, and that these feelings sharply contrast the relatively normative expectations concerning réintégration. In these cases, the patient's psychiatric environment tends to structure the reintegration process. However, people who have not been rehospitalized are characterized by a dominant type of réintégration that is best described as"posi-tive retreat" ("retrait positif). This characteristic is supported by various psychological, social and cultural hypotheses. Moreover, an intercultural perspective suggests that certain traits in North American societies tend to make people look down on "positive retreat" and view this form of readaptation as negative.

English Abstract↗
PubMed1986

[Questioning the obvious.].

The actual language on mental health in Quebec is founded on a série of premises that generally remain implicit or are introduced as postulates of "good will" with regard to reality. The authors want to question the significance and the real range of those premises by using a comparative analysis. Considering the concept of desinstitutionalization as used in different countries, they detect the ambiguities and the differences due to the context and to the postulates specific to each of those systems. Then, to elaborate our own premises, they utilize a decentralization method: with the help of their knowledge of other cultural ways of reacting to the problems of psychiatry-mental health, on the one hand in Africa, and on the other from data gathered in Quebec from psychiatric patients, ex-patients and friends. This twofold study leads them to express, compare and criticize what they introduce as the three main premises of mental health language in Quebec: to popularize psychiatric-mental health problems and to introduce a standardization of the people and a uniformity of structure in a field that remains very complex. A study of the theoretical character of this model, of its moralizing dimension and of the key-actors who contribute to its definition, allows them to describe the socio-historic context. The authors question the possibility of introducing a new dimension in our ways of thinking, management and action.

English Abstract↗