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Biomedical subjects

R Eloy

Publications and source records attributed to R Eloy.

At least 73 records · Page 4Linked to original sources
PubMed1983

Macromolecular, histological, ultrastructural and immunocytochemical characteristics of the neointima developed within PTFE vascular grafts. Experimental study in dogs.

The nature and characteristics of the tissue that develops on the inner surfaces of vascular arterial PTFE prostheses have been investigated by histological, morphometrical, ultrastructural, and immunocytochemical criteria. The ability of this tissue to synthetize glycoproteins and glycosamino-glycuronoglycans (previously called mucopolysaccharides) has been compared to that of the normal arterial wall. PTFE prostheses were used for carotid replacement in the dog and studied until the 90th postoperative day. These prostheses were mainly characterized by (1) a limited or even absent neointimal tissue proliferation; (2) the absence of an endothelial-like structure on the prosthesis using scanning electron microscopy and immunocytochemical staining with rabbit antidog factor VIII-related antigen sera; (3) limited activities of both microsomial enzymes (sialyl transferase and N-acetyl-glucosaminyl-transferase) but marked xylosyl transferase activity; and (4) inverse qualitative distribution of the glycosaminoglycans, i.e., decrease of heparan sulfate and chondroitin-6-sulfate and increase of hyaluronic acid and dermatan sulfate. The absence of morphological evidence of an endothelial structure at the blood--prosthesis interface even 3 months after implantation and the marked functional impairment in the biosynthesis of macromolecular components responsible for the normal blood--vessel interface suggest that this newly developed tissue cannot be considered a true vascular endothelium.

Animals↗
PubMed1983

Immediate and long-term evolution of the blood-venous graft interface. Experimental study in dogs.

Endothelial damage and repair in autogenous saphenous vein grafts was evaluated serially from 30 s to 9 months after implantation into the femoral arteries of 25 dogs. Light and scanning electron microscopy, quantitative morphometry and cytochemistry with specific rabbit antidog factor VIII-related antigen were used. These studies demonstrate: (1) early complete endothelial cell desquamation both on the venous graft and adjacent artery apparently related to dissection and suture; (2) differing early platelet activation on the venous and adjacent arterial wall, platelet aggregates were noted on the adjacent artery, whereas only adhesive platelets are noted on the exposed vein graft; (3) endothelial reconstitution being initiated after 10-15 days but not reaching completion even 9 months after implantation; (4) a mediointimal proliferation which is a constant feature. A unique cell possessing both fibroblastic and myocytic characteristics takes part in the process.

Animals↗
PubMed1983

Diminished osmotic and chemically induced haemolysis of human erythrocytes following exposure to contrast media molecules.

Radiocontrast molecules (RCM) used in coronaroangiography and/or urography diminished their osmotic fragility when they were incubated for 30 min with human erythrocytes. The shift of the osmotic fragility curve towards lower NaCl concentration is related to the hypertonicity of RCM, but in addition, at a given osmolality (100 +/- 5 mosm/kg), RCM at the concentration of 4-10% v/v increase the resistance to osmotic lysis or even suppress it. Similar protection is observed towards erythrocyte lysis induced by a detergent (saponin), polyenic antibiotic (filipin) or non-polyenic cholesterol-specific agent (digitonin). The effect is (1) proportional to the amount of RCM present, (2) independent of hypertonicity of the molecule, and (3) related to the nature of acidic molecules. A weak insertion of RCM into the erythrocyte membrane is suggested since it was suppressed by a single washing of the cells.

Contrast Media↗
PubMed1983

Absence of complement activation in vitro by sodium meglumine ioxitalamate.

The effect of radiographic contrast media on proteins of the complement system in vitro was investigated using protein level measurement and crossed immunoelectrophoresis. Despite the 20% loss of total serum hemolytic activity (CH50) induced by sodium meglumine ioxitalamate (0.5 M), no significant changes in C3c, C3N or B were detected by radial immunodiffusion. These contrast media did not cause electrophoretic conversion of C3, as assessed by the absence of split product, and the small degree of spontaneous C3 conversion (loss of 20% C3N antigen and the presence of two peaks with C3c antigen) which occurred when serum was incubated in polypropylene tubes, was inhibited by the contrast media. The effects of sodium meglumine ioxitalamate and zymosan in vitro on complement activation were compared.

Blood Proteins↗
PubMed1982

Contrast agents used for excretory urography impair platelet function in human patients.

The platelet function was investigated in 65 patients submitted to diagnostic excretion urography (injection of 60 ml contrast medium). Blood sampling was performed before (T0) 90 seconds after (T1) and 30 minutes after (T2) injection of the radiocontrast molecule (RCM). Five RCM of different osmolality ionicity and nature of the lateral chain have been tested. Platelet aggregation, platelet release of ATP, osmolality, total calcemia and ionized calcium level were determined on each plasma sample as well as RCM concentration at T1 and T2. Decrease (20 - 40%) of platelet aggregation occurred at T1, whichever platelet aggregating agent (ADP, collagen, Ristocetin or thrombin) were used (significant after Iopamidol 300 and Na Meg Ioxaglate). Platelet release of ATP induced by collagen was also decreased or delayed. These changes were rapidly reversible and a tendency to improvement was observed at T2. Among the five RCM tested, one (Na Diatrizoate) might be a proaggregating agent. No changes of osmolality occurred in the plasma and no correlation could be established between RCM concentration and platelet inhibition. A pathogenic hypothesis is suggested by the significant fall of total and ionized calcium level after RCM injection.

Adenosine Triphosphate↗
PubMed1982

Evaluation of a microvascular prosthesis of microporous polytetrafluoroethylene in rats.

Polytetrafluoroethylene grafts were used as a microvascular prosthetic material in rats with a patency rate of 75 per cent. Immediate evaluation of the interface by scanning electron microscopy and histologic examination confirm the blood compatibility of the material, that is, limited platelet and erythrocytic activation or fibrin formation, or both. However, a longer evaluation period as great as three months fails to demonstrate the development of an endothelial lining which does not cross over the suture lines. Similarly, at this time, the immediate adjacent artery remains also devoid of typical endothelial structure. This result suggests that endothelial reconstitution, if present, even on normal substructures remains a delayed process.

Animals↗
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

[Distribution of glycoconjugates in the arterial wall following contact with alloplastic materials: morphologic study and biochemistry of glycosamino-glycurono-glycans].

The infrarenal aortas of dogs were replaced with Woven Dacron prosthesis for the purpose of studying the structural and molecular modifications of the arterial wall in contact with the prosthetic material. After removal, the graft and its host arteries were submitted to biochemical analysis of glycosamino-glycurono-glycans (GAG) and to morphological analysis by scanning electron microscopy (SEM). Biochemical results demonstrated that the tissues growing within the prosthesis had a similar composition to intimal-media layers of normal arterial walls, but had a different distribution, especially of hyaluronic acid whose anionic character is enhanced. In opposition the tissue surrounding the grafts had a distribution of GAG similar of cicatrization tissues. Nevertheless SEM studies of the internal surface of the grafts demonstrated only the presence of fibroblastic cells without endothelial cells.

Animals↗