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Biomedical subjects

M L Couble

Publications and source records attributed to M L Couble.

At least 37 records · Page 2Linked to original sources
PubMed1991

Odontoblast-like cytodifferentiation of human dental pulp cells in vitro in the presence of a calcium hydroxide-containing cement.

The cement produced microcrystals of calcite by reaction with culture medium supplemented with calf serum. Human dental pulp cells seeded on such a substrate preferentially adhered and aggregated around the microcrystals. Immunofluorescence and immunogold labelling revealed a high affinity of serum fibronectin molecules for the calcite crystals. At 4 weeks in culture, the cells had various features of differentiated odontoblasts, notably nuclear polarization, typical appearance of the Golgi apparatus, synthesis of type I collagen and absence of type III, and apical accumulation of actin and vimentin. These cells also elaborated a collagenous extracellular matrix which did not mineralize.

Adolescent↗
PubMed1991

Differential expression of type I and type III collagen genes during tooth development.

Collagen gene expression during mouse molar tooth development was studied by quantitative in situ hybridization techniques. Different expression patterns of type I and type III collagen mRNAs were observed in the various mesenchymal tissues that constitute the tooth germ. High concentration for pro-alpha 1(I) and pro-alpha 2(I) collagen mRNAs were found within the osteoblasts. We found that the cellular content of type I collagen mRNAs in the odontoblasts varies throughout the tooth formation: whereas mRNA concentration for pro-alpha 1(I) collagen decreases and that of pro-alpha 2(I) increases, during postnatal development. Moreover, different amounts of pro-alpha 1(I) and pro-alpha 2(I) collagen mRNAs were observed in crown and root odontoblasts, respectively. Type III collagen mRNAs were detected in most of the mesenchymal cells, codistributed with type I collagen mRNAs, except in odontoblasts and osteoblasts. Finally, this study reports differential accumulation of collagen mRNAs during mouse tooth development and points out that type I collagen gene expression is regulated by distinct mechanisms during odontoblast differentiation process. These results support the independent expression of the collagen genes under developmental tissue-specific control.

Animals↗
PubMed1991

Isolation and characterization of rat alveolar bone cells.

Samples of rat alveolar bone were first treated by collagenase digestion and then used as explants for cell culture. The cells obtained were subcultured and characterized by morphological and functional criteria. Their alkaline phosphatase activity was increased after incubation in 1,25-(OH)2 vitD3 10(-8) M whereas with gingival cells it did not change. The bone derived-cells organized nodular structures, synthesized type I collagen, Gla-protein, few type III collagen, and fibronectin. In the defined culture conditions no mineralization was observed. However, the method used allows to obtain cells from rat alveolar bone displaying some features of the osteoblastic phenotype.

Alveolar Process↗
PubMed1990

Expression of fibronectin and type I collagen by human dental pulp cells and gingiva fibroblasts grown on fibronectin substrate.

Specific antibodies and indirect immunoperoxidase labelling were used to study the intracellular production of collagen and fibronectin by cells grown on fibronectin-coated glass; the same cell populations seeded on uncoated glass were used as controls. Strong intracellular staining for type I collagen was seen in all cases, but immunostaining for fibronectin was very faint or negative in both gingival and pulp cells grown on the fibronectin substrate, in contrast to control cells. Thus, fibronectin substrate inhibited fibronectin synthesis by the cultured cells, but did not seem to influence type I collagen synthesis.

Cells, Cultured↗
PubMed1990

Ultrastructural and immunocytochemical study of bone-derived cells cultured in three-dimensional matrices: influence of chondroitin-4 sulfate on mineralization.

Bone-derived cells were cultured in three-dimensional reconstituted matrices made of type I collagen or type I collagen chondroitin-4-sulfate. As observed by microscope, their characteristics were as follows: The cells deposited a faint extracellular matrix mainly composed of type I collagen. In the collagen-chondroitin-sulfate sponge fibers, a calcification process, which involved the deposition of hydroxyapatite crystals, was demonstrated. Mineralization occurred only in collagen chondroitin sulfate sponge fibers when seeded with bone-derived cells and was not seen with nonosteogenic cells, such as gingival fibroblasts. Gla protein was intracellularly visualized in both types of sponges seeded with bone-derived cells while an extracellular secretion was seen only in the collagen chondroitin sulfate sponge fibers where calcification occurred. These results suggest that collagen chondroitin sulfate promotes in vitro mineralization of three-dimensional collagen matrices when seeded with bone-derived cells.

Animals↗
PubMed1989

Immunohistochemical study of types I, III and IV collagen in diseased human gingiva of patients with rapidly progressive periodontitis: a light and electron microscopic study.

The distribution of type I, III and IV collagens and their ultrastructural organization have been studied in diseased gingival connective tissue of patients with rapidly progressive periodontitis. This disease is characterized by acute destruction of the gingival collagenous components. The use of an immunofluorescent procedure has shown that the diseased connective tissue was made up of both type I and III collagens but that type III collagen was less resistant to acute inflammation. Ultrastructural immunolabelling, using the peroxidase procedure has shown that the large, dense bundles of type I collagen of PI, the main pattern of organization of the gingival connective tissue offered a better resistance to acute destruction than PII, a loose pattern of organization mainly composed of type III collagen. Type IV collagen was exclusively located in degraded lamina densa of basement membrane.

Adult↗
PubMed1988

Distribution and organization of the elastic system fibres in healthy human gingiva. Ultrastructural and immunohistochemical study.

The ultrastructural distribution and organization of the elastic system fibres, i.e. oxytalan, elaunin and elastic fibres, were studied by transmission electron microscopy and by an immunohistochemical method for the detection of elastin in healthy human gingiva. The morphological distribution of these fibres was characterized by the presence of oxytalan, elaunin and elastic fibres, respectively, in the upper, medium, and deep layers of gingival connective tissue. Anti-elastin antibody reacted with microfibrils and amorphous material of the elastic system fibres throughout the gingival connective tissue. These findings were interpreted as indicating that the microfibrils were associated with small amounts of elastin at their surface.

Adult↗
PubMed1987

Developmental switches of sericin mRNA splicing in individual cells of Bombyx mori silkgland.

Four mRNA of 10.5, 9.0, 4.0, and 2.8 kb are made from the sericin Ser1 gene by alternative maturation of a unique mRNA precursor. By means of RNA blots and in situ hybridization, we investigated variations in the distribution of these mRNA during the last larval instar in different territories of the middle silkgland. Taken together, the results from these two techniques show that 150 out of the 266 cells of this region of the organ express the Ser1 gene, but accumulate distinct mature mRNA species. Of these 150 cells 42 are specialized in a processing pathway resulting in the production of the 2.8-kb Ser1 mRNA throughout the larval instar. The 108 others perform successively three distinct splicing pathways leading to a development-dependent accumulation of, respectively, the 4.0-, the 10.5-, and the 9.0-kb mRNA. This suggests the occurrence of two switches in the splicing capacities of these cells during the fifth instar. The middle silkgland cells also express another sericin gene (Ser2) which encodes two mRNA of 5.4 and 3.1 kb, also arising by differential splicing. At the beginning of development, all the middle silkgland cells express this gene but, as development proceeds, expression becomes restricted to only the anterior cells. The biological consequence of this topological and temporal regulation of the mode of expression of these two genes is the sequential secretion and layering of the different sericins around the silk thread.

Animals↗
PubMed1987

Evaluation of the biocompatibility of a Ni-Cr-Mo dental alloy with human gingival explant culture in vitro: morphological study, immunodetection of fibronectin, and collagen production.

This study was undertaken to evaluate the biocompatibility of a Ni-Cr-Mo dental casting alloy by an in vitro explant culture method. Through ultrastructural features, the immunolabelling of fibronectin, and the immunodetection of type I and III collagen production, we investigated the behaviour of gingival cells (both fibroblasts and epithelial cells) in contact with the alloy in comparison with control cultures. Our results indicate that cultured gingival cells present a well preserved ultrastructure and synthesized fibronectin (the main glycoprotein involved in adhesion to substrates). The alteration of collagen production concerned only type III collagen which decreased significantly in the cultures on the dental alloy.

Cells, Cultured↗
PubMed1986

Ultrastructure of multilayered cultures of human gingival epithelial cells: attachment to enamel surfaces in vitro.

Human gingival cells were collected using an enzymatic procedure and seeded on a feeder layer of irradiated mouse 3T3 fibroblasts. Epithelial cells generate stratified colonies ultimately forming an epithelium which was studied using electron microscopy. When this epithelium-like structure was dispased and transferred to enamel surfaces, the relationship between basal cells and enamel corresponded to half-desmosomes and a discontinuous extracellular matrix.

Adult↗
PubMed1985

Influence of fixative on the fine structure of mouse odontoblasts: a study on undemineralized tissue.

The present report describes techniques of fixation and embedding suitable for studying the fine structure of odontoblasts without demineralization. The quality of the procedures employed was verified by comparing the ultrastructural preservation of the odontoblasts prepared by simple fixation and by the double-fixation method. Simple fixation by immersion in osmium tetroxide in vacuum preserves the longitudinal arrangement of the rough endoplasmic reticulum and Golgi apparatus, showing various vesicles which often contain filamentous threads of weak electron density aligned in parallel at repeating intervals typical of odontoblastic cells. The results obtained with this method are compared to previous descriptions of the ultrastructure of odontoblasts.

Animals↗