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Biomedical subjects

C Baquey

Publications and source records attributed to C Baquey.

At least 73 records · Page 4Linked to original sources
PubMed1992

Experimental evaluation of a collagen-coated vicryl mesh as a dural substitute.

Dural substitutes must provide immediate restitution of a membranous covering for the brain without inducing any adverse reaction in the host or provoking adhesions to underlying nervous tissues. Ideally, the material should disappear completely and be replaced by tissues similar to the dura mater. In this study, parietal dural defects were created in 12 beagle dogs and closed with a vicryl mesh prosthesis made watertight by a film of bovine collagen. Clinical and biological tolerances were satisfactory. There was one case of early local infection. Gross and microscopic examinations performed between 7 days and 9 months after implantation showed degradation of the prosthetic mesh and connective tissue growth into the implant mimicking dura mater as early as 15 days after implantation. There was no attendant inflammatory reaction or cortical adhesions or other adverse reactions. The authors conclude that collagen-embedded vicryl mesh provides satisfactory biological function and compatibility when used as a substitute for dura mater in the dog.

Animals↗
PubMed1992

Hemocompatibility of titanium nitride.

The left ventricular assist device is based on the principle of the Maillard-Wenkel rotative pump. The materials which make up the pump must present particular mechanical, tribological, thermal and chemical properties. Titanium nitride (TiN) because of its surface properties and graphite because of its bulk characteristics have been chosen. The present study evaluated the in vitro hemocompatibility of TiN coating deposited by the chemical vapor deposition process. Protein adsorption, platelet retention and hemolysis tests have been carried out. In spite of some disparities, the TiN behavior towards albumin and fibrinogen is interesting, compared with the one of a reference medical grade elastomer. The platelet retention test gives similar results as those achieved with the same elastomer. The hemolysis percentage is near to zero. TiN shows interesting characteristics, as far as mechanical and tribological problems are concerned, and presents very encouraging blood tolerability properties.

Adsorption↗
PubMed1991

Microencapsulation of isolated pituitary cells by polyacrylamide microlatex coagulation on agarose beads.

Microlatex beads of homogenous size were made by polymerization of a mixture of acrylamide/bisacrylamide dispersed in a microemulsion. The microlatex was aggregated by dilution of the microemulsion in acrylamide solutions. The aggregates were then coagulated by polymerization at the interfaces of agarose beads circulating in a capillary tube containing paraffin oil. Biocompatibility was tested on isolated pituitary cells microencapsulated by this procedure.

Acrylamide↗
PubMed1991

Rationale for the design of biomaterials and the evaluation of their biocompatibility.

The biocompatibility of a material can be considered as the ideally expectable result of its interactions with living tissues with which it is interfaced. This property determines the ability of devices involving this material in their constitution, to correctly assume their ascribed function; reciprocally a bad fitting, between devices and their intended use, coming from a non-optimized design or from an inappropriate prescription, may alter the original biocompatibility of constitutive materials. Accordingly, the actual biocompatibility of a biomaterial depends upon both its intrinsic properties and the application in which it is involved. Such considerations must be taken into account by specialists who try to design more performant biomaterials, or new assist devices, should they be implantable or not; but they draw also methodological guidelines for the evaluation of the biocompatibility of these biomedical products.

Biocompatible Materials↗
PubMed1990

Biological behavior of cellulosic materials after bone implantation: preliminary results.

The biological behaviour of cellulosic material was examined after intermedullary implantation in femoral shafts of rabbits. The examination of rabbits' femurs occurred at 3, 9, 12 and 34 weeks by X-ray, microscopic and macroscopic examinations. They showed a perfect bone-implant adaptation without macroscopic or X-ray modification of the bone and without any cortical secondary weakness. In spite of the difficulties arising from the retraction of dehydrated cellulose before methylmethacrylate embedding, microscopic aspects show, at the end of the implantation, a very low inflammatory reaction with bone intra-spongious regeneration of cells and the integration of the cellulosic implants. These results are encouraging for success in new applications of cellulose in orthopaedic surgery.

Animals↗
PubMed1990

Biocompatibility of polyacrylamide microcapsules implanted in peritoneal cavity or spleen of the rat. Effect on various inflammatory reactions in vitro.

The biocompatibility of polyacrylamide microcapsules was investigated by implanting microcapsules in the peritoneal cavity or the spleen of rats. The capsules were retrieved every four weeks for twenty weeks. They remained isolated and free in the peritoneal cavity, but led to a slight inflammatory reaction in the spleen. These results were confirmed, in vitro, by determinations of chemiluminescence and interleukin I levels, and by evaluation of attachment and growth of human fibroblasts. The microcapsules did not enhance these inflammatory reactions, and they were a poor support for cellular proliferation.

Acrylic Resins↗
PubMed1989

Biocompatibility of carbon-carbon materials: blood tolerability.

Carbon-carbon composites are well known in the field of aerospace technology. Such composites have been proposed to be used as biomaterials, particularly in contact with blood. To evaluate their haemocompatibility, samples were tested in vivo and in vitro, using radiotracers. In vivo study showed the accumulation of platelets on the exposed surface material with any surface morphology, whereas platelet concentration in blood remained constant. In vitro study allowed us to distinguish, among entrapped platelets, active adhering platelets from those mechanically retained and it appeared that the bulk structure of materials influenced the adhesion mechanism of platelets.

Animals↗
PubMed1989

Experimental evaluation of a gelatin-coated polyester graft used as an arterial substitute.

Protein coating and endothelial cell preseeding have been proposed and studied as improvements to arterial prostheses. In this paper, an impervious polyester vascular graft which had been coated with cross-linked gelatin was compared to a porous one over a period of up to 8 months in dogs. This evaluation involved in vivo methods using radio tracers to study patency and thrombogenicity and in vitro controls of the healing processes. The main advantages offered by coated grafts over uncoated include the absence of preclotting and better biointegration.

Animals↗
PubMed1988

In situ polymerization of a microencapsulating medium round living cells.

A new process for microencapsulating living cells is described. Pancreatic islet cells in solution in agarose were extruded from a syringe into a paraffin-oil-containing medium. A rigid interface around each bead was produced when the agarose gelled. A polymerizable mixture of monomers containing 30% of acrylamide and 1.5% of bisacrylamide was then added to these beads. Polymerization was initiated by a photochemical process using riboflavin as a photosensitizer, which enabled use of oxygenated solutions. As other polymerizations initiated by an oxido-reduction reaction, this method did not require heating, and could thus be carried out at ambient temperature. The oil phase near the agarose beads effectively prevented any rise in temperature, and also led to formation of an acrylamide concentration gradient in the aqueous phase, which reduced the potential cytotoxicity of the reaction. Radioimmunoassay of insulin liberated from encapsulated islets of Langerhans demonstrated a good viability of the cells.

Acrylamides↗
PubMed1988

Biocompatibility of carbon-carbon materials: in vivo study of their erosion using 14carbon labelled samples.

Several uncertainties have to be resolved concerning the in vivo erosion of carbon-carbon composite materials and the outcome of the resulting particles. We studied these phenomena with implants superficially doped with 14carbon, specially prepared using the usual production processes of these materials. The samples implanted in rats presented changes in their measured radioactivity which proved erosion. Autoradiographies of the whole animal as well as pathological studies of peri-implanted tissues with histoautoradiographies of the related sections revealed the presence of carbon at a distance from the implant. However, the majority of the eroded particles were retained in the fibrous capsule surrounding the implant. The methods of electron-diffraction, associated with electron microscopy, seem to be a tool suitable to characterize the nature (fibrous or pyrolytic) of the carbon particles present in the capsule.

Animals↗
PubMed1988

Control and isotopic quantification of affinity of antithrombin III for heparin-like surfaces.

Heparin-like materials, characterized by a defined superficial density of functional groups which activate antithrombin III (AT III), when in contact with blood specifically inhibit thrombin as soon as it appears. This paper describes an isotopic method to estimate this density and to visualize the distribution of the affinity sites concerned, both directly with AT III labelled with 125Iodine and indirectly with an anti AT III monoclonal antibody labelled with 111Indium.

Adsorption↗
PubMed1988

[Preservation of the functional integrity of cellular material after cell microencapsulation by polymerization].

A new process for microencapsulating living cells is described. A cross linked network was polymerized using acrylamide and bisacrylamide monomers round agarose-embedded cells in an hydrophobic medium. The reaction was initiated by excitation of Vit. B2 under visible irradiation. The absence of toxic effect was evaluated from the insulin secretion of encapsulated islets of Langerhans.

Animals↗
PubMed1987

Radiosterilization of albuminated polyester prostheses.

The study reported here is concerned with the radio-sterilization of Dacron vascular prostheses coated with crosslinked albumin. gamma-Radiations have no effect on the mechanical properties of the polyester fibres or on their crystallinity, whether irradiated in a dry state or immersed in saline. Special attention has been paid to the release of the albumin, or protein fragments from the reticulum using 125I-labelled albumin as a radiotracer. The albumin leakage depends upon the type of Dacron fabrics considered but the values derived from radioactivity measurements are always greater than those directly measured, which indicates a radio-induced break of the bond between iodine and albumin; this has nothing to do with the break of the association between albumin and Dacron. Moreover no cytotoxicity of the irradiated immersion medium has been observed using a test based on organotypic culture in liquid medium. Thus radio-sterilization of an albuminated polyester vascular prosthesis immersed in saline appears to be a suitable procedure.

Albumins↗
PubMed1987

Conditions for radioiodination of antithrombin III retaining its biological properties.

In order to obtain a radioiodinated antithrombin III (AT III) with a good labelling yield and optimal biological properties towards heparin, thrombin and its anti-AT III monoclonal antibodies, we compared the classical labelling methods and found them wanting. Thus, we perfected a new labelling procedure which fulfils the above requirements.

Antithrombin III↗
PubMed1986

Topographic and dynamic radioisotopic investigations of interactions between biomaterials and blood components.

Functional investigations using radionuclides to study protein adsorption and platelet adhesion onto biomaterials are described. The authors' novel methods use radiotracers with a dynamic technique. This allows direct observation of the interaction between blood, or simpler biological substances, and artificial materials. Several radiotracers were used in this study, including 111In-platelets, 123I-fibrinogen, 123I-antithrombin III, and 99mTc-tagged red blood cells. The detectors employed were a semiconductor diode or gamma-camera equipped with special collimators. The acquisition and treatment of data were performed with an original device. These methods allowed precise comparisons, especially between platelet adhesion upon different materials in the form of tubes and also protein adsorption and desorption. The results are discussed in terms of materials to be used for work in vivo.

Adsorption↗