Search PubMed⌕ Search

Biomedical subjects

E Chignier

Publications and source records attributed to E Chignier.

At least 19 recordsLinked to original sources
PubMed1992

A member of the selectin family (GMP-140/PADGEM) is expressed on thrombin-stimulated rat platelets in vitro.

1. Granule membrane protein (GMP-140) is an integral alpha-granule membrane glycoprotein, expressed on the surface of human platelets following degranulation, and is part of a new family of adhesion molecules (selectins) related to the endothelial leukocyte adhesion molecule (ELAM-1) and to the lymphocyte homing receptors in man (Leu-8/TQ1) and in mouse (gp90MEL-14). 2. The cross-reactivity with rat platelets of the monoclonal antibodies (MAb), LYP20 and S12, directed against human GMP-140 was examined, with the purpose of assessing the homology of GMP-140 between human and rat platelets and of using positive MAbs to detect platelet activation in vivo in response to vascular disease in rats. 3. By ELISA technique, LYP20 gave a greater OD reading with thrombin-stimulated rat platelets than with resting platelets. 4. 125I-LYP20 bound significantly more to thrombin-stimulated rat platelets (3875 +/- 750 molecules/platelet) than to resting platelets (645 +/- 240 molecules/platelet, P less than 0.01) with 50% maximum binding at 0.13 +/- 0.02 microgram/ml; 125I-S12 did not bind to rat platelets. 5. By fluorescence-activated flow cytometry there were significantly more fluorescent thrombin-stimulated platelets (56 +/- 7% of total), compared with resting platelets (8 +/- 1% of total, P less than 0.001). 6. Western blots of rat platelet lysates showed that LYP20 bound to a single band identified, under non-reducing conditions, as having the same apparent M(r) as GMP-140. 7. LYP20 immunoprecipitated a protein which became radiolabelled on the surface of thrombin-activated rat platelets; S12 did not recognize any protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Peritoneal macrophage response: an in vivo model for the study of synthetic materials.

This study was designed to validate an in vivo model in rat to study cell-implant interactions. Pieces of Dacron and Goretex and polydimethylsiloxane (reference material) precoated or not were implanted in the peritoneal cavity. In some cases the peritoneal cells were stimulated before the implantation. Macrophage phagocytosis and fibrinocoagulolytic activities were investigated in parallel with morphological studies 6 h after implantation. A graded cell response related to the different situations was observed, providing a measure of the material's behaviour. Using this model, other investigations of macrophage/polymer can be conducted, especially to explain implant encapsulation.

5'-Nucleotidase↗
PubMed1991

Assessment of a potentially noninvasive method for monitoring aortic blood flow in children.

Ultrasonic methods have rendered possible noninvasive quantitative blood flow measurement. In this work, a method is proposed to measure aortic blood flow in children by means of a specially designed miniaturized esophageal probe and an autonomous apparatus combining an M-mode imaging system and a pulsed Doppler. In vivo experimental results in animals are presented and demonstrate the interest of simultaneous and continuous measurement of aortic diameter and blood flow velocity giving accurate measurements. A 0.94 correlation coefficient is found when comparing blood flow in the descending aorta measured using this method and using an electromagnetic flowmeter.

Animals↗
PubMed1991

Effect of nimodipine on subintimal hyperplasia of autologous vein bypass grafts in rats: a placebo-controlled study.

Autologous vein grafts are commonly used conduits for coronary bypass grafts. However, as many as 20% of the grafts may occlude in the first year to a subintimal hyperplasia. Although the initiating mechanism remains unclear, it has been demonstrated that subintimal hyperplasia is dependent upon smooth muscle cell proliferation and migration from the medial to the intimal layer. The present study focused on the prevention of smooth muscle cell proliferation using a calcium antagonist. A vein bypass graft from the jugular vein on the abdominal aorta was performed in 40 rats, divided into two groups of 20. Animals in the treated group received nimodipine (15 mg/kg of body weight), and those of the control group received a placebo. Nine months after grafting, the results showed that the group receiving nimodipine presented no or only slight subintimal hyperplasia as compared with the placebo group (p less than 0.001). The data presented in this study show that nimodipine can reduce subintimal hyperplasia in rats and strongly suggest that a calcium antagonist could be employed in the prevention of venous graft disease.

Animals↗
PubMed1991

Inhibition of subintimal hyperplasia of autologous vein bypass grafts by nimodipine in rats: a placebo-controlled study.

An arterial bypass may be required for the management of neoplastic or cerebrovascular disease. When an arterial graft is not suitable, autologous vein grafts are the most commonly used conduits; however, as many as 20% of the vein grafts used in vascular surgery may occlude as a result of subintimal hyperplasia. Although the mechanism initiating subintimal hyperplasia remains unclear, it is known that subintimal hyperplasia is dependent upon smooth muscle cell proliferation and migration from the media to the intimal layer. The present study focused on the prevention of smooth muscle cell proliferation using a calcium antagonist. Forty rats received an autologous vein bypass graft from the jugular vein to reconstruct the abdominal aorta. They were randomly divided into two groups of 20 rats each. Animals in the treated group received a calcium antagonist (nimodipine), and those in the control group received a placebo. Nine months after grafting, the group receiving the calcium antagonist presented no or only slight sub intimal hyperplasia as compared with the placebo-treated group (P less than 0.001). These data suggest that a calcium antagonist could be used for the prevention of venous graft disease.

Animals↗
PubMed1990

Lipid accumulation in prosthetic vascular grafts. Experimental study.

The present study demonstrates that the endoprosthetic tissue, developed at the contact of Dacron and Gore-Tex vascular prostheses replacing the infrarenal aortae of healthy dogs, presents a particular lipidic pattern as compared with the adjacent intimal arterial layer. The modified lipidic pattern is characterized by a significant increase in the total amounts of cholesterol, phospholipids, and triglycerides, despite a normal lipidic plasma profile. Histochemical studies showed that lipid droplets are accumulated in the cytoplasm of deeply situated cells and in the extracellular matrix. These findings support the idea that lipids may be trapped within the pseudo-intima of synthetic vascular grafts, even in the absence of a major plasma lipid disorder, and contribute to the prosthesis failure.

Animals↗
PubMed1989

[The neoartery, myth or reality? Study of 79 explanted arterial prostheses].

This study represents the third stage of a personal study on the long term fate of reconstruction and arterial restoration materials presented to the Academie de Chirurgie. 79 explanted prostheses were studied. First of all by an in depth histological study (8 cases selected from 70 reinterventions carried out before 1980), and then by a more complete protocol: scanning electron microscopy, resistance testing, programmed differential calorimetry, X-ray diffraction and biochemical analysis (71 reinterventions carried out after 1980). Our findings agree with the studies of R. Guidoin. With the exception of structural manufacturing defects or defects related to surgical manipulation, mechanical fatigue in a Dacron (PET) arterial prosthesis is inevitable: on average by the 7th to 10th year, a prosthesis looses one half of its mechanical resistance. The covering tissue, like that of the external capsule, which has poor mechanical properties, cannot compensate for prosthetic deterioration which may be considered to be complete by the 25th year. Knitted arterial prostheses, especially aortic, more rapidly undergo dilatation than woven prostheses which are much more resistant. On the other hand, the poor compliance of the latter compared with the recipient artery, perhaps favorises late anastomotic rupture. At internal capsule or pseudo-intimal level, endothelium is never present, but rather there is a permanent turnover with a variable time course, the mechanisms of which are poorly understood (role of prostaglandins?). Rather than a neo-artery, the vascular surgeon is only capable of producing an imperfect arterial tube, fragile from many points of view, and having an evolution which remains poorly understood.

Aneurysm↗
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↗
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↗
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↗