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Biomedical subjects

C Couture

Publications and source records attributed to C Couture.

42 records · Page 3Linked to original sources
PubMed1990

A novel thymic epithelial adhesion molecule.

Interactions between thymocytes and thymic stromal cells are responsible for positive and negative selection of T cell, their differentiation, maturation and proliferation. The signals required for these events to occur often necessitate close contact, and indeed adhesion, between the cell types involved. The identification of specific adhesion molecules in this context, is, therefore, a vital first step in determining the nature of the signal they mediate or facilitate at a given stage of differentiation. In the present work we identify, isolate and partially characterize a ligand present on thymic medullary epithelial cells which selectively binds CD4+ CD8+ thymocytes found primarily in the thymic cortex. This adhesion molecule is composed of two non-covalently associated glycoproteins of 23 kDa and 45 kDa, respectively, both of which are needed to bind to thymocytes. The importance of the finding is that the ligand, in isolated immobilized form, binds the same thymocyte subset as the original epithelial cell line from which it was isolated. The CD4+ CD8+ thymocyte subset is the precursor of single-positive mature T cells; hence the putative biological activity of the ligand in question takes place at a pivotal stage of T cell differentiation.

Animals↗
PubMed1989

Binding of cortical thymocytes to a medullary epithelial cell line: a brief review.

In this review, we bring together data regarding complexes formed between thymocytes and a line of thymic epithelial cells, E-5. We show that E-5 has all the markers which identify it as of epithelial and medullary origin. We show that thymocytes which form complexes with it belong to the double positive, CD4 + CD8 + population, and that the receptor responsible for binding to epithelial cells is likely to be an as yet unidentified glycoprotein. The ligand on E-5 cells is also a glycosylated protein. Adhering thymocytes are in a state of mitotic activity, and their incubation with E-5 cells does not induce increased responsiveness to polyclonal mitogens. Non-adhered thymocytes, on the other hand coincubated With E-5 cells increase their responsiveness to ConA and initiate responsiveness to PHA. Differentiation of adhering thymocytes is evidenced by their acquisition of refractoriness to a secondary adherence, and by the modification of their surface phenotype.

Animals↗
PubMedDate not supplied

3D MR image analysis of the morphology of the rear foot: application to classification of bones.

The purpose of this work is to characterize the three-dimensional (3D) morphology of the bones of the rear foot using MR image data. It has two sub-aims: (i) to study the variability of the various computed architectural measures caused by the subjectivity and variations in the various processing operations; (ii) to study the morphology of the bones included in the peritalar complex. Each image data set utilized in this study consists of sixty sagittal slices of the foot acquired on a 1.5 T commercial GE MR system. The description of the rear foot morphology is based mainly on the principal axes, which represent the inertia axes of the bones, and on the bone surfaces. We use the live-wire method [Falcao AX, Udupa JK, Samarasekera S, Shoba S, Hirsch BE, Lotufo RA. User-steered image segmentation paradigms: live wire and live lane. Proceedings of the Society of Photo-optical Instrumentation Engineers 1996;2710:278-288] for segmenting and forming the surfaces of the bones. In the first part of this work, we focus on the analysis of the dependence of the principal axes system on segmentation and on scan orientation. In the second part, we describe the normal morphology of the rear foot considering the four bones namely calcaneus, cuboid, navicular, and talus, and compare this to a population from the upper Pleistocene. We conclude that this non-invasive method offers a unique tool to characterize the bone morphology in live patients towards the goal of understanding the architecture and kinematics of normal and pathological joints in vivo.

Adult↗
PubMedDate not supplied

The effects of nutritional quality and frequency of consumption of sugary foods on dental caries increment.

This study investigates the association of dietary quality with dental caries increment of 11-year-old children. A 3-day dietary record including one weekend day was completed by the subjects and their parents. The nutritional quality was evaluated using a quality index based on the eating frequency of foods recommended in food guides and divided into 8 levels. The frequency of consumption of sugary foods, liquid and solid, at and between meals was also calculated. Two oral examinations 20 months apart were made in 1983-85; each time, the quality of oral hygiene was determined by using the simplified oral hygiene was determined by using the simplified oral hygiene index of Greene and Vermillon. the dental caries increment between the two examinations was evaluated using the DMFS index. When the subjects were distributed into 3 groups according to their nutritional quality index, the mean dental caries increment had a tendency to decrease as the nutritional quality increased for the total sample as well as for boys and girls considered separately; however, the analysis of variance did not reveal any differences of statistical significance. No association was established for children in this study between frequency of consumption of sugary foods and caries increment. No association was observed between nutritional quality and oral hygiene nor between the mother's education and the children's frequency of consumption of sugary foods. Thus, in our study, children with the highest dental caries increment are not necessarily the ones having a diet of poor nutritional quality nor the ones consuming sugary foods more frequently.

DMF Index↗