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Biomedical subjects

E Chignier

Publications and source records attributed to E Chignier.

At least 37 records · Page 2Linked to original sources
PubMed1986

Adventitial resection of small artery provokes endothelial loss and intimal hyperplasia.

While adventitial resection is a part of the preparation of microvessels for operation, the procedure may provoke damage to the vessel wall. The histologic and ultrastructural endothelial lesions associated with adventitial resection, the interface of the blood vessel and the course of endothelial repair are discussed herein. The adventitia of the abdominal aorta of rats was stripped under microscopic magnification (32X) around the whole circumference of infrarenal segment of 1 centimeter in length. The rats were sequentially sacrificed. Fixation and silver staining were carried out in vivo. The specimens were collected at six, 12 and 24 hours, at seven, 15, 30 and 90 days, and at six, nine and 12 months after injury. These specimens were studied by en face light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of en face light microscopy and SEM investigations showed: an initial severe trauma of the endothelial surface leading to complete de-endothelial areas as early as six hours after injury, the lesions were limited to the adventitial resected areas; at seven days the polygonal cells were recognized in silver stain preparation; at 30 days the endothelial surface was partially reconstituted but cells had large protoplasmic areas, TEM in the same time period confirm the absence of the endothelial cells up to 30 days; at 90 days the reconstitution of the endothelial layer was almost complete, and intimal hyperplasia was observed already at one month and appeared to have stabilized at six months postoperatively with three to four cell layers. These results suggest that: adventitial resection immediately provokes endothelial desquamation; endothelialization is a slow process when large areas are involved, and intimal hyperplasia may develop even on an autologous arterial segment, thus providing new insight to the etiopathogeny of vascular graft initial hyperplastic reactions.

Animals↗
PubMed1985

Long-term behavior of bovine collagen membrane used as vascular substitute. Experimental study in rats.

The aim of the present study was to evaluate the sequence of the immediate and the mid/long-term organization of the blood interface of a collagenous membrane used as vascular substitute in rats. The implants were prepared from calf skin type I insoluble collagen, obtained after acidic dispersion, in absence of chemical or tanning treatment. They were used to patch an aortic defect by means of microsurgical techniques. The animals were sequentially sacrificed for immediate hemocompatibility studies at 10 s, 30 s, 10 min, 3 h, and 6 h, for long-term analyses of the organization of the blood material interface at the 7th, 15th, 45th, 60th, 90th day following the surgery and each month until 14 months after aortic replacement. The superficial immediate events at the blood patch interface demonstrated erythrocytes heavily engulfed in a thin but dense fibrin mesh both at the patch and at the adjacent aortic wall surfaces. Neither adherent platelet nor platelet aggregate were detectable on the collagen patch surface. This fibrinoerythrocytic membrane covered the patch completely at 60 s and at 3 h the deposit was limited to 5-6 erythrocyte layers as confirmed by histology. It did not further develop on the 7th day. At the blood-collagen interface there progressively developed a tissue composed of active myofibroblasts, collagen bundles, and elastic fibers. After 4 months, nests of fibroendothelial cells were present, and between 6 and 14 months surface cell differentiation, although complete on the adjacent aorta was still incomplete on the bovine collagen patch, amorphous fibers, and fibroendothelial cells coexisting. Heterologous patch debris were still present 14 months after implantation and were associated with macroscopic and ultrastructural calcification, which need further investigations concerning the exact nature and mechanism of mineralization of vascular substitutes of biological nature.

Animals↗
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↗
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

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

[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↗
PubMed1980

Macromolecular and histological studies of new tissue formation in velour vascular prostheses.

The nature and characteristics of the tissue which develops on the inner surfaces of vascular arterial prostheses have been investigated by means of histological and biochemical criteria. Velour prosthetic tubes were implanted as aortic segmental replacements in the dog. On the 60th postoperative day, a neointimal layer of collagen covered with flattened endothelial-like cells was noted. However, despite this morphological evidence the microsomic and cytosolic enzymes implicated in the biosynthesis of glycosamino-glycuronoglycans were significantly modified in comparison with the normal aortic wall. The marked decrease in enzymes corresponding to the initiation of the glucidic linkages suggests that the biosynthesis of the macromolecular components responsible for the normal blood vaessel interfact was impaired in these newly developed tissues. Therefore, it is suggested that this newly developed tissue cannot be considered as a true vascular endothelium.

Acetylglucosamine↗
PubMed1980

Another look at the Sparks-Mandril arterial graft precursor for vascular repair. - Pathology by scanning electron microscopy.

The Sparks-Mandril blood vessel precursor system, an autogenous tissue growth-promoting device, in spite of its ingenuity and its surgical elegance, has received only limited usage. At technique for peripheral blood vessels by several authors. In the latter period, this laboratory also undertook similar work. The results of seven implantations in dogs and two in patients are reported here in the context of a program on the evaluation of blood vessel substitutes, their mode of operation and their long term performance. The clinical status and the pathology of the grafts at time of failure were investigated using techniques of scanning electron microscopy. This work confirms the findings of other centres regarding the generally unsatisfactory performance of the Sparks-Mandril system. Possible causes for failure in mandril-formed blood vessels are discussed.

Adult↗
PubMed1979

Revascularization of the spinal cord by micro-anastomoses in dogs.

The severity of ischemic lesions in the spinal cord justifies attempts at its surgical revascularization. The experiments consisted of: (1) creating devascularization of the conus medullaris by ligation of all the lumbo-sacral collaterals of the aorta, and (2) revascularizing the lumbo-sacral rachidian circulation by performing an end-to-side anastomosis between the caudal mesenteric artery and the 5th left lumbar artery (from which in the dog the Adamkiewicz artery generally arises). After two-months, the patency rate of the 20 cases was 85%. Such a procedure of revascularization could be useful in man in cases of interruption of the arterial supply of the spinal cord.

Angiography↗
PubMed1978

[Mechanism of biosynthesis of glycoconjugates at the level of the arterial walls after contact with alloplastic materials (author's transl)].

The object of this work was to show that here exists after contact with foreign substances, a construction of protein, glycoprotein and mucopolysaccharide macromolecules at the level of the intima of the great vessels. Woven Dacron prostheses have been implanted in the arterial circulation of dogs (on the subrenal abdominal aorta). After removal of vascular segments, we carried out a subcellular fractioning, controlled and studied in an acellular system in vitro the activity of the glycosyltransferases implied in the construction of glycan chains of glyccproteins. The results are discussed in relation to the duration of implantation of the prosthesis. The modifications observed differ according to the position of the sugars in the glycan chains, in particular as far as sialic acid is concerned, and lead to an interpretation of the mechanism of endovascular reactions when faced with foreign material.

Animals↗
PubMed1978

Mechanism of glycoconjugates biosynthesis in the vascular wall with external circular constraint.

Extrinsic local constraints, realised on dogs aorta are responsible for parietal lesions in the form of thickening of the arterial wall. Histological changes in the intima and media are characteristic of processes of degeneration destruction and cellular regeneration, superposed on sub-endothelial proliferation accompained by partial or total destruction of endothelial cells in the intimal layer. In addition to histological changes, there were perturbation in enzymatic activities of glycosyltransferases responsible for macromolecular constructions in the intima. Microsomic enzymes studied were: N-acetyl-glucosaminyl-transferase, sialyl-transferase and N-acetyl-galactosaminyl-transferase, and two glycosyl-transferases located in the soluble cytoplasmic phase: fucosyl and xylosyl-transferase. The changes observed were different according to the position of the sugars in the glycoprotein chains. For example the variation of fucosyl-transferase activity is significant: it disappears in group where the sialyl-transferase activity is enhanced. The transfer of xylose is decreased. Finally, changes observed in hexosaminyl-transferase activities were parallel.

Animals↗