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Biomedical subjects

G Dureau

Publications and source records attributed to G Dureau.

At least 73 records · Page 4Linked to original sources
PubMed1987

Characterization of the tissue proliferated at the blood interface of carbon/ceramic composites.

The present study focuses on cell adhesion/differentiation and material stability of surfaces of the three carbon/ceramic composites implanted in intra-atrial position in dogs for 1 year. Before implantation their surface was characterized by scanning electron microscopy. After harvesting, the tissue proliferated on the blood interface was examined by histology, scanning, and transmission electron microscopy, wavelength dispersive and x-ray spectrometry, electrophoretic and enzymatic characterization of glycosaminoglycans (GAGs) which were compared to endocardiac tissue as control samples. One year after implantation, the pattern of GAGs in the newly developed tissue was characterized by: 1) a constant increase of the total GAGs present on all carbon composites, 2) a significant increase of dermatan sulfate (p less than 0.05), 3) a significant increase of chondroitin sulfate (p less than 0.05), 4) a significant decrease of heparan sulfate in Group 1, whereas this GAG fraction was increased in Groups 2 and 3. Cellular surface differentiation towards endothelial-like cells occurred in places particularly in groups 1 and 3, whereas only fibrous tissue was found covering the implants in Group 2. Fibroblastic cells with dense intracellular deposits, which produced emission of Si, Ca, and C energy as well as extracellular lipidic containing inclusions were observed. The macromolecular modifications were associated with 1) the absence of endothelial lining, 2) the migration of carbon and silicon particles, and 3) the occurrence of calcifications and lipidic inclusions. These results suggest that the relative smoothness of these materials could be responsible for the development of a tissue that did not adhere to the biomaterial, indicating that cell adhesion and functional differentiation are in intimal relationship with the physical-chemical structure of the material surface.

Animals↗
PubMed1987

Haemocompatibility and biological course of carbonaceous composites for cardiovascular devices.

A new class of carbonaceous composites has been developed for cardiovascular devices. The aim of the present study, performed in dogs, was to test the immediate blood compatibility of these materials when inserted within the vascular bed. Biocompatibility studies were performed on vascular cylinders (6 mm i.d.) and intra-atrial implants. The specimens were examined sequentially by SEM at 10, 20, 30, 180 s and 10 min after re-establishment of the blood flow. Patency of the vascular cylinders was tested during the second and third postoperative month by Doppler ultrasound investigations; specimens were examined by light and electron microscopy (scanning and transmission) at 15, 60 and 110 d following implantation. As early as 10 s after re-establishment of the blood flow platelet adhesion and a limited fibrin mesh with few erythrocytes developed on the material. Platelet aggregates were only observed on intravenous implants. Except in the case of the intravenous insert, no thrombosis developed at the contact of intra-arterial or intracardiac implants. After 15 d it was completely covered by a fibrocellular layer (3-5 cells thick) consisting of large myofibroblasts with microfilaments, newly synthesized collagen and elastin. Endothelial-like cells developed and were completed 2 mnth after implantation. However, deposits present inside and outside the fibrocytic cells of the newly developed tissue were observed corresponding to carbon peaks as indicated by wavelength dispersive X-ray microanalysis.

Animals↗
PubMed1985

Local changes in myosin types in diseased human atrial myocardium: a quantitative immunofluorescence study.

Two monoclonal antibody groups were prepared from adult human atrial and ventricular myosin heavy chains. Using these two groups, we were able to identify two myosin variants in human atria and to classify human atrial fibers into alpha-, mixed, or beta-fibers according to the reactivity of the two monoclonal antibody groups to alpha- and beta-myosin heavy chains of normal young and hypothyroid rat ventricles, respectively. The alpha-fiber percentage of the left atria in two normal human hearts was 15% higher than in the right atria. The auricles contained two to three times more alpha-fibers than beta-fibers, whereas the proportion was reversed in the crista terminalis. The mean fiber diameter of the alpha- and beta-fibers was 13.6 +/- 3 micron. A complete alpha- to beta-fiber transition was observed in all atrial regions of two hearts with severe ventricular myocardial infarction; a moderate alpha- to beta-fiber transition was observed only in the left atria of two hearts with primary congestive cardiomyopathy. The mean diameters of the two fiber types were significantly increased in all diseased hearts (19 +/- 3.8 micron). We hypothesize that pressure overload and increased wall tension successively induce an enlargement of the fiber diameter and an alpha- to beta-myosin transition.

Adolescent↗
PubMed1982

[Thoraco-bisternotomy in cardiovascular surgery].

Median sternotomy associated with anterior lateral thoracotomy with section of the sternum opposite the gaping intercostal space is a classical, though rarely used, incisional approach. The authors are convinced that it is safe, easy to perform and well tolerated. Their experience in 14 cases without morbidity shows that its alleged problems are more theoretical than real. They recommend this approach for aneurysms of the thoracic aorta and in some cases for access to the atrial area and superior vena cava.

Aortic Dissection↗
PubMed1981

Biological and mechanical behavior of autologous pericardium used for tricuspid valvular replacement in dogs.

The fate of autologous pericardium when used to replace a tricuspid valve leaflet has been investigated in dogs. Changes have been studied by means of macroscopic, mechanical, histological, scanning electron microscopy, and in vitro culture techniques. In each of nine experiments the valve failed and death occurred within the first 15 post-operative days. Retraction, thickening of the cusp, fibrinous deposition and/or tissue rupture were associated with a decrease of resistance to traction tests, decrease of elasticity and increase of viscosity of the implanted tissue. The early behavior of autologous pericardium was characterized by precocious inflammatory reaction on the valve leaflets, focal disruption of the collagenous structure of the leaflets, absence of fibroblastic cell infiltration as confirmed by in vitro culture of implanted pericardium and the lack of endothelial-like cell surface at the 10th-15th postoperative day.

Animals↗
PubMed1981

Course of the initial epithelial lesions associated with autologous bile duct replacement. Experimental study in rats.

Mucosal lesions and healing of the common bile duct were analyzed after various chemical and surgical insults in the rat by means of histologic and scanning electron microscopic investigations. Autogenous bile duct replacement is rapidly associated within the first 72 postoperative hours with complete epithelial cell desquamation, and its precocious consequence is biliary sludge. These lesions also occurred when the bile flow was diverted; the extrinsic devascularization and denervation did not produce extensive epithelial cell loss. Heparin perfusion within the biliary tree or the induction by glycerol of epithelial cell loss before bile duct transplantation is suggested in order to avoid extensive biliary sludge after bile duct transplantation.

Animals↗
PubMed1981

Effects of glycerol pretreatment upon biliary or venous grafts in bile duct replacement.

With the use of microsurgical procedures, sequential studies have been done to compare the short and long term outcome of the bile duct and the femoral vein as autogenous bioprostheses of the bile duct. Nonpretreated grafts of both types are associated with an early superficial cell loss, either epithelial or endothelial. An initial biliary sludge resulted with further consequences, that in biliary stasis, lithiasis and biliary cirrhosis. Both grafted ducts became epithelialized but were the site of an extensive inflammatory reaction followed by fibrosis within the underlying connective tissue and retraction of the graft. On the contrary, pretreatment of the grafts by immersion in concentrated glycerol allowed the initial cell shedding to occur before implantation. The process of epithelialization and glandular formation was not altered in these conditions, whereas the inflammatory and fibrotic reaction in the duct wall was reduced or absent.

Animals↗
PubMed1981

In vivo release of a heparin-like factor in dogs during profound hypothermia.

Experimentally induced hypothermia (20 degrees C) for 60 minutes in dogs provokes a significant decrease in the platelet count, which reverses during subsequent rewarming, and the constant release of a heparin-like factor, which reacts as a specific inhibitor of factor Xa. This phenomenon is also rapidly reversible, and heparin values are not significantly different from control levels after 90 minutes of rewarming. The mean maximal concentration of heparin-like material is 0.54 U/ml, or about double control levels. Its half-life is approximately 90 minutes. The level of circulating antithrombin III was not modified during hypothermia and rewarming.

Animals↗
PubMed1978

[Decrease in stimulation and allogeneic response following experimental infection of mice with human adenovirus 5].

15 days after experimental infection with human adenovirus 5, C57 Bl/6 murine spleen cells were found to have altered in vitro properties. Proliferative response to phytohemagglutinine was slightly increased while the allogeneic response was decreased and the capability to stimulate allogeneic cells was significantly diminished. The degree of expression of surface antigens responsible for allogeneic stimulation is influenced by many regulatory factors, still poorly defined; alteration of some factors of antigenicity may result, directly or indirectly, from certain viral infections.

Adenoviruses, Human↗
PubMed1978

[Variation of the inflammatory response of an autologus implant function and viability: mixed and unilateral inflammatory response].

The behaviour of an autologous grafted implant depends upon its viability. In our study, pericardial implants were used as cardiac valves. Results showed that when using fresh live pericardium, an inflammatory response developed destroying it within 8 days. When implants cells were killed without alteration of their antigenicity--in order to prevent rejection--cellular growth and neovascularisation from implantation site occurred leading to a secondary live graft. Controlled killing of the implant seems to be an essential step in order to get live grafts.

Animals↗