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Biomedical subjects

H Magloire

Publications and source records attributed to H Magloire.

At least 55 records · Page 3Linked to original sources
PubMed1990

Cytokeratins as molecular markers in the evaluation of the precise differentiation stage of human gingival epithelium reconstituted in vitro.

Cytokeratins are considered to be molecular markers for different types of epithelial differentiation. They were used to investigate the precise differentiation stage of gingival epithelium, reconstituted in vitro, following two different culture procedures. Human trypsin-dissociated gingival keratinocytes were seeded either on a feeder layer of irradiated mouse 3T3 fibroblasts or on a connective tissue equivalent (lattice) made up of human fibroblasts in a collagen gel. The cytokeratins were extracted and analysed by two-dimensional gel electrophoresis. Although both methods showed on histological sections that cultured gingival keratinocytes formed a multilayered non-keratinizing epithelium, the cytokeratins patterns showed great differences. The gingival epithelium-like structure reconstituted on 3T3 feeder layer expressed some cytokeratins characteristic of the in situ gingival epithelium (K 5, 6, 14, 16, 17) and some which do not exist in the normal tissue (K 8, 18, 19, traces of K 13 and K 15) and are specific for embryonic, simple and tumour epithelia. However, the gingival epithelium reconstituted on connective tissue equivalent expressed all the cytokeratins present in the normal tissue (K 5, 6, 14, 16, 17), except those specific for terminal differentiation (K 1, 2, and 10/11). These findings suggest that the culture of gingival keratinocytes on connective tissue equivalents allows them to reproduce physiological stages of differentiation.

Biomarkers↗
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↗
PubMed1990

[Epidermal growth factor in tooth development].

The epidermic growth factor (EGF) inhibits the morphogenesis and cellular differentiation of dental tissues during embryogenesis. These effects are modulated according to the stage of tooth development. Thus, the cupula stage seems markedly affected contrary to the bell stage which continues to evolve eve in the presence of EGF. Distribution of EGF receptors is altered during the first stages or the morphogenesis and this is specific for each stage of dental development. Finally, some rare pathological processes, related to the EGF level, are particularly characterized by a very early growth of the teeth.

Epidermal Growth Factor↗
PubMed1990

Collagen gene expression and tooth development. An overview.

The regulation aspects of type I and type III collagen gene expression are examined and the relationships with tooth morphogenesis and differentiation are discussed. Type I and III collagens constitute the major molecular proteins of the dental tissues. In addition the collagen gene expression in the mesenchyme derived odontoblasts represents an important step in the cytodifferentiation at the mesenchymal level. Furthermore, odontoblasts seem to synthesize only type I and type I trimer collagens, but not type III collagen. Therefore, the aim of this overview is to describe the molecular mechanisms that control the expression of specific collagen genes during the process of odontoblast differentiation. The available data support the main transcriptional control and argue for the existence of an independent and developmental regulation during collagen gene expression in odontoblast cells.

Animals↗
PubMed1989

Immunoelectron microscopic localization of dentin gamma-carboxyglutamic acid-containing proteins in differentiating rat odontoblasts.

The intracellular synthesis of the dentin-gamma-carboxyglutamic acid-containing proteins (DGPs) by rat odontoblasts was investigated at the electron microscopic level using a sensitive pre-embedding immunoperoxidase technique. The DGPs were detected in the rough endoplasmic reticulum and secretory vesicles, but not in the Golgi apparatus of the odontoblasts, while dentin matrix is not yet reactive. These results suggest that the DGPs synthesis is independent of mineral deposition.

1-Carboxyglutamic Acid↗
PubMed1989

Immunolocalization of cathepsin D in dental tissues.

Cathepsin D antigenicity was localized at the light and electron microscopic levels within dental cells, but not in extracellular matrix. Different intracellular sites for cathepsin D were found depending on the cell type: the enzyme was detected in secretory vesicles of the odontoblasts and in the lysosome-like structures of the ameloblasts. Otherwise, these results suggest that the secretory vesicles of the odontoblasts may contain both cathepsin D and type I collagen. These data might implicate cathepsin D in the enamel and the dentin formations.

Animals↗
PubMed1989

Human recombinant gamma-interferon stimulates proliferation and inhibits collagen and fibronectin production by human dental pulp fibroblasts.

Human recombinant-gamma-interferon was tested on human dental pulp fibroblast activity in vitro. Fibroblast proliferation was estimated by a colorimetric test. Type I and type III collagens and fibronectin were quantified by radioimmunoassay in culture supernatant from confluent fibroblasts. A dose dependent stimulation of the proliferation was observed when fibroblasts were treated with recombinant-gamma-interferon. In contrast, an inhibition of the synthesis of soluble types I and III collagen and fibronectin by confluent cell cultures treated with recombinant-gamma-interferon occurred without apparent modification of the insoluble collagen level in the cell layer. Quantimetric analysis of type I collagen immunoperoxidase labelling have demonstrated that there was no intracellular storage of type I collagen in these cultured fibroblasts. These data support the view that human recombinant-gamma-interferon can affect human dental pulp fibroblast functions and thus may play an important part in the regulation of fibrosis.

Cell Division↗
PubMed1989

[Use of human epithelial cultures in mucogingival surgery].

A clinical technique utilizing autologous cultured epithelial cells in vestibule deepening operations is described. Epithelial cells from oral mucosa were grown in tissue culture on a feeder layer, released from their flasks and placed with the basal side up on the recipient beds. The cultured cells induced rapid healing of the wound, which was free of pain and contractions. The greatest advantage of this technique is that there is no size limitation on wounds that can be covered by cultured epithelial cells.

Adolescent↗
PubMed1989

[Recent concepts on amelogenesis: towards a molecular understanding of the pathology of human enamel].

Recent studies concerning amelogenesis demonstrate the key role of ameloblasts in the elaboration of mature enamel; this highly differentiated epithelial cell elaborates a specific extra-cellular proteic matrix, secondarily mineralized and participating in the elaboration of mature enamel. While the matrix of immature enamel is essentially made of two main classes of proteins--amelogenins and enamelins--specific proteins are found in mature enamel, the tuft proteins as well as enamelin-type proteins. In light of recent results concerning enamel proteins, we will review the different pathological processes of human enamel. In fact, the clinical observation of various forms of imperfect amelogenesis enables to recognize several aetiological mechanisms. This could either be a pathological process of genetic nature originating in the ameloblast--imperfect, mendelian-type amelogenesis--or secondary abnormalities of the calcification process, without anomalies of the genes responsible for the protein framework, which could be called post-ameloblastic pathological process.

Ameloblasts↗
PubMed1988

Localization of 28 kDa calbindin in human odontoblasts.

The presence of 28 kDa calbindin in human odontoblasts was studied by use of specific antibodies raised against chick duodenal 28 kDa calbindin, in immunofluorescence, immuno-peroxidase, and electron-microscopic labelling experiments. The calbindin-like protein was detected mainly in the cytoplasm of odontoblast cell bodies, in their processes and occasionally in their nuclei. Correspondingly, at the ultrastructural level, immunoreactive material was associated with the cytosol, microfilaments and cilia. These findings suggest that human odontoblasts express a 28 kDa vitamin D-dependent calcium-binding protein, unlike those of rats and mice in which ameloblasts are the only cells immunoreactive for the protein.

Animals↗
PubMed1988

Distribution and synthesis of type I and type III collagens in developing mouse molar tooth root.

The distribution and synthesis of type I and type III collagens in the mouse molar tooth root have been investigated by correlating light and electron immunohistochemical data. Purified rabbit antibodies were raised against mouse type I and type III collagens and indirect immunoperoxidase procedures were used. In these conditions, predentin, pre-bone, and pre-acellular cementum were intensely immunostained for type I collagen. Both optic and ultrastructural data confirmed the presence of type I collagen at the epithelio-mesenchymal junction, but Hertwig's basement membranes remained unlabelled. The odontoblasts including the short polarized ones, osteoblasts, some cells of pulp mesenchyme and the perifollicular cells possessed type I collagen immunoreactivity in the rough endoplasmic reticulum (RER), Golgi complex and the secretory vesicles. Type III collagen immunoreactivity was strong in the perifollicular mesenchyme, light in the pulp mesenchyme and absent from the epithelio-mesenchymal junction, the predentin, pre-bone and pre-acellular cementum. Intracellular immunolabelling was detected at the ultrastructural level in the perifollicular cells by a faint homogeneous peroxidase deposit in the RER cisternae. Finally, these results, compared with previous biochemical and morphological data, represent the first dynamic aspect of collagens distribution and synthesis in the mouse molar root development. In terms of cell differentiation, our data also suggest that type III collagen synthesis does not occur during the odontoblast process of differentiation.

Animals↗
PubMed1988

Localization and synthesis of type III collagen and fibronectin in human reparative dentine. Immunoperoxidase and immunogold staining.

The injury of dental pulp tissue, following caries, is accompanied by the deposit of a typical hard scar tissue known as reparative dentine which should be regarded as the mineralization of a new organic matrix. Highly purified antibodies were used in combination with immunoperoxidase or immunogold technique at the ultrastructural level to reveal the distribution and synthesis of types I and III collagen and fibronectin elaborated by typical matrix-forming cells in the new tissue. Specific immunoperoxidase labelling, on demineralized teeth, clearly demonstrated that type I collagen represents the main type of collagen (88%). It is associated with bundles of fine striated fibrils of type III collagen and in close vicinity with fibronectin and constituted, at least, the new organic matrix of reparative dentine. Immunogold staining gave precise localization mainly over Golgi apparatus for the 3 components, thus suggesting that the cells concerned should not be considered as new odontoblasts but rather as pulpal cells in the process of differentiation participating in the formation of new dentine. Moreover, these events are very similar to those observed during wound healing in other tissues.

Collagen↗
PubMed1988

Trichomonas tenax: ultrastructure of giant forms.

Trichomonas tenax is a parasitic flagellate of the human mouth. The morphology and the ultrastructure of the protozoan are identical to those of other trichomonads. Giant forms suddenly appeared in a strain maintained in culture for two years. The structure and the ultrastructure of these abnormal forms were studied at the light and electron microscope level. Several nuclei, groups of flagella, undulating membranes and Golgi complexes were observed. The significance of these forms is still unknown.

Animals↗
PubMed1987

mRNA characterization of human fetal enamel matrix.

Preliminary characterization of the human enamel matrix at 16-18 weeks in utero was performed. Using an homogenizing buffer, the proteins were extracted and analysed by gel electrophoresis. Total cellular RNA was isolated and the cell-free mRNA translated. The major component was a 68,000 protein with an enamelin-like amino-acid composition. Other translation products included a 55,000 polypeptide and lower mol. wt components of 26,000, 22,000 and 20,000 size of amelogenin size. It is suggested that high mol. wt component in the enamelin range is the most prevalent at the early stage of human tooth development.

Amino Acids↗
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↗
PubMed1987

Mechanical properties and biocompatibility of two polyepoxy matrices: DGEBA-DDM and DGEBA-IPD.

The aim of this paper was to study the biocompatibility and mechanical properties of materials for orthopaedic and odontologic surgical use. The products used were obtained by polycondensation of a diepoxy resin (DGEBA) with two curing agents (DDM or IPD). The materials present a slight swelling in liquid medium and their thermomechanical properties are hardly affected after 12 month implantation. The absence of molecular desorption in isotonic liquid and human serum confirms their hydrolytic stability and thus their inertia. These materials do not give rise to an intolerance reaction by neighbouring tissues during implantation time (1 d to 12 month).

Aniline Compounds↗