Biomedical subjects

H Chardin

Publications and source records attributed to H Chardin.

22 records · Page 2Linked to original sources

PubMed1990

Visualization of glycosaminoglycans in rat incisor extracellular matrix using a hyaluronidase-gold complex.

The enzyme-gold technique was used on dental tissues. Hyaluronidase was complexed with gold, and ultrathin sections of rat incisors were incubated with the hyaluronidase-gold complex to localize chondroitin-sulphate and hyaluronic acid at the ultrastructural level. The hyaluronidase-gold complex was found in predentine and dentine, especially at the mineralization front, in interglobular spaces and around dentinal canaliculi. The very young enamel was labelled, but not the later stages of formation. This method allowed a very precise localization of hyaluronic acid and/or chondroitin sulphate in rat incisors extracellular matrices. These findings support the important role of glycosaminoglycans in dentine mineralization.

Amelogenesis↗

PubMed1990

Visualization of glycosaminoglycans in rat incisor predentin and dentin with cetylpyridinium chloride-glutaraldehyde as fixative.

Using cetylpyridinium chloride (CPC) in glutaraldehyde as fixative, we observed sinuous fiber-like structures 300-500 nm long and 7-14 nm thick in the spaces between the collagen fibers of rat incisor predentin. Small granules and fibrils were also detected. Electron-dense vesicles were seen inside the odontoblast processes. The plasma membrane was irregularly stained with material that adhered to its surface. In demineralized dentin, needle-like structures were seen at the periphery of globular structures which were not stained. Staining the sections with Alcian blue did not greatly improve the visualization of CPC-precipitated glycosaminoglycans. The specificity of staining was assessed on serial sections by selective dissociation of glycosaminoglycan aggregates with 2 M calcium chloride and their digestion by bovine testicular hyaluronidase. The glycosaminoglycans were probably combined with lipids, because treatment of the sections with a chloroform/methanol mixture removed the CPC-induced precipitates from both predentin and dentin.

Aldehydes↗

PubMed1989

Effect of tunicamycin on glycogen accumulation in the stratum intermedium and odontoblasts of rat incisor.

Repeated injection of rats with tunicamycin over two days induced a 1- to 5-fold increase in glycogen. This accumulation occurred in the stratum intermedium of the enamel organ and in young secretory odontoblasts. In rats injected over 3 days, the number of glycogen particles was at least 10 times larger than in control rats, and large glycogen accumulations were observed in the cytosol of these two groups of cells. These results were obtained by staining with periodic acid-thiocarbohydrazide and silver proteinate, a specific method for the detection of glycoconjugates containing vic-glycol groups. The existence of a relationship between these local cytosolic accumulations of glycogen and the developmental stage of certain groups of cells was shown by the changes that occurred in glycogen distribution. The present results suggest that the stratum intermedium supplies energy for precursor transport.

Animals↗

PubMed1987

Characterization of axolotl heavy and light immunoglobulin chains by monoclonal antibodies.

Axolotl specific antibodies to 2,4-dinitrophenyl (DNP) were purified by affinity chromatography from the sera of animals immunized with 2,4,6-trinitrophenylated sheep red blood cells (TNP-SRBC). The purified anti-TNP/DNP antibodies, when analyzed by SDS-PAGE, were constituted of high molecular weight molecules, which in reducing conditions, were separated into heavy 72-88 kD and light 27-30 kD polypeptides. The axolotl heavy antibody chains strongly bound Concanavalin-A and migrate faster in SDS-PAGE after endoglycosidase-F (Endo-F) treatment. Using the same techniques, no carbohydrate components were detected onto light chains. Monoclonal antibodies (MAbs) were obtained against these purified axolotl immunoglobulins (Ig) and their specificities were studied by immunoblotting. MAbs 33.45.1 and 33.101.2 respectively recognized heavy and light chains determinants of the Ig molecule. These determinants were resistant to Endo-F digestion, suggesting that the two MAbs were not directed to polypeptide-associated N-linked high mannose or complex oligosaccharides. MAbs 33.45.1 and 33.101.2 were compared to 11.5.2, an anti-axolotl thymocytes MAb which was reactive for both axolotl leucocytes and soluble Ig. MAb 11.5.2 reacted in immunoblotting against several high molecular weight axolotl serum proteins, including heavy Ig chains. Light chains were not recognized. However, 11.5.2 did not further recognize Endo-F treated Ig, suggesting its specificity for a carbohydrate determinant of the heavy chain, and link to a large diversity of soluble or membrane glycoproteins.

Ambystoma↗