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Biomedical subjects

B Dupuy

Publications and source records attributed to B Dupuy.

At least 73 records · Page 4Linked to original sources
PubMed1976

[The localization of calcium in the rat thyroid].

The (glyoxal bis 2 hydroxyanil-calcium) complex is used to localize calcium in the rat thyroid. With low temperature and freezed slices, the colloid calcium content seems more important than that of epithelium.

Animals↗
PubMedDate not supplied

Evolution of the local calcium content around irradiated beta-tricalcium phosphate ceramic implants: in vivo study in the rabbit.

To evaluate whether dissolved calcium from tricalcium phosphate implants contributes to osseous wound healing in bone defects, the authors used nuclear radioactivated materials. Six months after irradiation, the calcium was still radioactive. Samples of the material were prepared and placed in rabbit condyles for 1, 3 and 9 months. Over time the condyles were retrieved and treated for histology or radiocounting. Measurements of the radioactivity of the slices and histomorphometry of the implants and surrounding tissues were performed. The authors observed that the radioactivity decreased regularly. Connective tissue had penetrated the pores and totally invaded the implants, first at the periphery of the implants, then inside the pores. Comparison of the results of radioactivity and histomorphometry suggest that part of the calcium from the implants was re-used specifically in the new osseous tissue.

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PubMedDate not supplied

Agarose encapsulation of islets of Langerhans: reduced toxicity in vitro.

The physical and chemical properties of agarose have been exploited for encapsulation of islets of Langerhans. Formation of microcapsules by extrusion of a hydrophilic polymer (agarose) into a hydrophobic solution created an interface to which an immunoprotective membrane could be polymerized. The substances and procedure used were devoid of cellular toxicity. Islet function in vitro was found to be normal.

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PubMedDate not supplied

Lack of responsiveness to glucose of microencapsulated islets of Langerhans after three weeks' implantation in the rat--influence of the complement.

Microencapsulated islets of Langerhans retrieved from peritoneal cavity of rats three weeks after implantation had a reduced hormonal secretion and were no longer responsive to alterations in glucose levels. Activation of complement could not completely account for the observed fibrosis which was thought to be responsible for the loss of responsiveness of the encapsulated cells.

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PubMedDate not supplied

In vitro diffusion in polyacrylamide embedded agarose microbeads.

125I Sodium iodide, 125I insulin, 125I albumin, and 111indium IGG were employed to investigate release from, and penetration of different sized molecules into agarose/polyacrylamide microcapsules. The microcapsules were formed by photopolymerization of an acrylamide solution round agarose beads. The indium-chelated antibody gave a particular low background count. The different release times were explained in terms of differences in diffusion coefficient. By retarding in vitro penetration of antibodies, these microcapsules could be of value for the encapsulation of living cells in bioartificial organs.

Acrylic Resins↗
PubMedDate not supplied

Peritoneal exudates from microencapsulated rat islets of Langerhans xenografted mice presenting characteristics of potentially cytotoxic non-specific inflammation.

Grafted polyacrylamide microencapsulated islets of Langerhans in the peritoneal cavity of mice did not survive more than a few days, perhaps owing to a non-specific inflammatory reaction or an immune rejection. To assess the two hypotheses, we used flow cytometry (FACS) to analyse cell populations of empty or islet-loaded microcapsules grafted in the peritoneal cavity of mice, and performed cytotoxic assays with proteases secreted by inflammatory cells. An immune rejection did not seem to occur, but the degree of inflammation could explain the short life of the grafts.

Acrylic Resins↗
PubMedDate not supplied

Encapsulation of calcitonin in liposomes depends on the vesicle preparation method.

Calcitonin-loading was studied in liposomes composed of phosphatidylcholine, cholesterol and stearylamine in relation to the vesicle preparation method. Liposomes entrapping calcitonin were prepared by extrusion, sonication or from mixed micelles through the elimination of cholate by gel filtration. To understand the mode of calcitonin encapsulation in the vesicles, riboflavin was entrapped within the vesicles and taken as a simple model for the encapsulation of molecules in the aqueous phase. Interactions of calcitonin with the liposomal membranes were evaluated by studying the fixation of radiolabelled calcitonin to the outer surface of empty liposomes, and by preparing calcitonin-loaded LDL-like nanoparticles composed of phosphatidylcholine and cholesteryloleate. Calcitonin entrapment in the vesicles depends largely on the vesicle preparation method. When vesicles are prepared by removal of cholate from mixed micelles, relatively little calcitonin entrapment in the liposomes is obtained. In this type of vesicle, calcitonin is exclusively embedded in the vesicle bilayer. When vesicles are prepared by extrusion or sonication, calcitonin is found both in the aqueous and lipidic phases of the vesicles. Optimal calcitonin encapsulation was obtained when the liposomes were prepared by sonication.

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