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Biomedical subjects

C Baquey

Publications and source records attributed to C Baquey.

83 records · Page 5Linked to original sources
PubMed1982

Postoperative evaluation of in situ saphenous vein bypass with technetium-labelled albumin microspheres.

Technetium-labelled serum albumin microspheres have been used to study arteriovenous shunting in in situ saphenous vein bypasses. Their diameter (15 micron) enables the microspheres to be trapped at the capillary level, either in the limb or in the lungs, according to the extent of arteriovenous shunts. The observed shunting ranged from practically nothing to 90%. The worst distal activity counts as well as the worst scintigraphic aspects (giving a qualitative view of the nutritional circulation of the limb) were found in patients with poor intraoperative arteriographic evaluation of run-off. Persisting clinical inconvenience due to fistulas was only found in patients with over 60% shunting. No patients, even those with up to 90% shunting, had any evidence of ischemia. Arteriovenous shunting would thus seem well tolerated to a certain extent, and the ligation of major arteriovenous fistulas is to be recommended.

Journal Article↗
PubMed1982

ESCA studies on heparin-like materials used for extracorporeal shunts.

Amino-acids sulfamide substituted polystyrene surfaces exhibit an heparin-like activity. Similar treatments were achieved on small diameter tubings made of polystyrene grafted on polyethylene. Electron spectroscopy for Chemical Analysis (ESCA) appeared as the suitable method for a chemical characterization of the surface (approximately 50-100 A depth) to be in contact with circulating blood. These tubings were implanted as extracorporeal shunts on dogs. The variations of local concentrations of labelled platelets, red cells and fibrinogen were recorded in situ. Depending on the conditions of preparation and implantation, a slight adhesion of platelet was observed. By using such type of materials with an improved mechanical compliance, small diameter antithrombogenic tubings could be developed, provided the chlorosulfonation prior to amino-acid grafting is mild.

Animals↗
PubMed1981

[Evaluation of arteriovenous shunts following venous by-pass with the saphenous vein in situ. A suggested approach (author's transl)].

An isotopic method employing microspheres of serum-albumin of a mean diameter of 15 microns was used to study the problem raised by the development of arteriovenous fistulae following saphenous by-pass in situ, enabling measurement of shunt flow and qualitative evaluation of the distal bed. Shunt blood flow varies greatly from practically negligible quantities to a maximum of 90%. Comparing data from angiography during operation with these data showed a parallel between the worst angiographic appearances, the poorest scintigraphy images, and the most marked shunts. Sustained clinical manifestations of the fistulae were apparent in shunts of over 60% only. Signs of ischaemia were absent, even in shunts taking 90% of by-pass blood flow. Arteriovenous fistulae induced by by-pass operations employing the saphenous vein in situ appear, therefore, to be relatively well-tolerated. Ligature of the most important, preferably proximal, collaterals is nevertheless recommended, to reduce disturbing side-effects as far as possible, and loss of flow to the distal arterial bed in cases with very large fistulae.

Angiography↗
PubMed1976

A new stannous agent kit for labelling red blood cells with 99TCM and its clinical application.

99Tcm is chosen for labelling erythrocytes for vascular imaging to take advantage of the physical properties of the radionuclide. A new procedure is described which belongs to the category of pre-treatment methods using a kit. Stannous pyrophosphate is the specific reducing reagent. The technique is easier than already published methods: it consists of adding the above reagent to 2 ml. of heparinized blood, waiting five minutes and discarding the serum after centrifugation, then adding the radioactivity required as 99TcmO4. Labelling yield is superior to 95 per cent. The influence of technetium concentration of the pertechnetate solution on the labeling yield is evaluated and compensated by a slight adjustment of tin concentration when necessary. In vitro and in vivo stability studies show that 99Tcm-labelled red cells are suitable for determination of red cell volume, spleen and placental imaging, particularly in emergencies and in paediatrics.

Blood Volume Determination↗
PubMedDate not supplied

Agarose encapsulation of islets of Langerhans: reduced toxicity in vitro.

The physical and chemical properties of agarose have been exploited for encapsulation of islets of Langerhans. Formation of microcapsules by extrusion of a hydrophilic polymer (agarose) into a hydrophobic solution created an interface to which an immunoprotective membrane could be polymerized. The substances and procedure used were devoid of cellular toxicity. Islet function in vitro was found to be normal.

Animals↗
PubMedDate not supplied

In vitro diffusion in polyacrylamide embedded agarose microbeads.

125I Sodium iodide, 125I insulin, 125I albumin, and 111indium IGG were employed to investigate release from, and penetration of different sized molecules into agarose/polyacrylamide microcapsules. The microcapsules were formed by photopolymerization of an acrylamide solution round agarose beads. The indium-chelated antibody gave a particular low background count. The different release times were explained in terms of differences in diffusion coefficient. By retarding in vitro penetration of antibodies, these microcapsules could be of value for the encapsulation of living cells in bioartificial organs.

Acrylic Resins↗
PubMedDate not supplied

Peritoneal exudates from microencapsulated rat islets of Langerhans xenografted mice presenting characteristics of potentially cytotoxic non-specific inflammation.

Grafted polyacrylamide microencapsulated islets of Langerhans in the peritoneal cavity of mice did not survive more than a few days, perhaps owing to a non-specific inflammatory reaction or an immune rejection. To assess the two hypotheses, we used flow cytometry (FACS) to analyse cell populations of empty or islet-loaded microcapsules grafted in the peritoneal cavity of mice, and performed cytotoxic assays with proteases secreted by inflammatory cells. An immune rejection did not seem to occur, but the degree of inflammation could explain the short life of the grafts.

Acrylic Resins↗