PubMed Health⌕ Search

Biomedical subjects

C Vigneron

Publications and source records attributed to C Vigneron.

At least 55 records · Page 3Linked to original sources
PubMed1995

Blood group antigen survival on freeze-dried erythrocytes and ghosts after isolation.

To screen and identify irregular antibodies, whatever the technique used, fresh erythrocytes (RBCs) are needed to set up the panel. Solid-phase tests using dried blood cells are available, but the technique is based on the adherence of sensitized RBCs, which have a short life span. We have checked antigen survival on membranes with a saline test and an antiglobulin test for two methods to preserve the antigen substrate: freeze-drying of RBCs and preparation of RBC membranes. The different antigens of the ABO, Rhesus, Kell, P, Lewis, MNSs, Lutheran, Duffy, Kidd and Li systems are well recognized on the membranes after isolation and on freeze-dried cells. Demonstration of antigen survival leads us to consider using membranes or freeze-dried cells in new immunological tests.

Blood Group Antigens↗
PubMed1995

In vitro effect of dextran-benzene-tetra-carboxylate hemoglobin on human blood rheological properties.

While conducting pharmacological investigations into oxygen carriers, it is important to study the in vitro and in vivo rheological behavior of blood cells in the presence of such preparations. With regard to the original nature of human hemoglobin bound to benzene tetracarboxylate substituted dextran (Dex-BTC-Hb), it seemed necessary to study its rheological effect in a simulated in vitro hemorrhagic shock compensated by a blood substitute. The viscosity of substitutes was determined as well as several rheological parameters after 0, 3 and 6 hours incubation periods of red blood cells with substitutes: viscosity of blood-substitute mixtures at different levels of plasma substitution erythrocyte aggregation of blood-substitute mixtures by determining the velocity of rouleau formation and the cohesion of rouleau network. This work yielded several observations: The viscosity of Dex-BTC-Hb was slightly higher than those of solutions of native Hb, Dex-BTC T10, Dextran 40 (Plasmacair, modified fluid gelatin (Plasmion and hydroxyethyl starch 200 (Elohes). The substitution of a blood volume with Dex-BTC-Hb, corresponding to a compensated 45% hemorrhagic shock, slightly increased the viscosity of hemodiluted blood as compared to other substitutes. In the presence of Dex-BTC-Hb, the aggregation of erythrocytes appears to be increased as compared to standard solutions. Yet, the effect was close to that of Plasmion or Elohes.

Blood Flow Velocity↗
PubMed1995

Assessment of dextran 10-benzene-tetracarboxylate-hemoglobin, an oxygen carrier, using guinea pig isolated bowel model.

With the aim of assessing of dextran-benzene-tetracarboxylate hemoglobin as an oxygen carrier, we studied histological changes in the intestinal loop in anesthetized guinea pig. The intestinal tissue being very sensitive to hypoxia, an innervated loop was vascularly perfused with open-flow during one hour at zero hematocrit. To estimate the capacity of hemoglobin solution to oxygenate this tissue, we observed the mechanical and histological changes in the organ and the arterio-venous difference in PO2, oxyhemoglobin, deoxyhemoglobin and we compared them with human albumin, Tyrode and non-modified hemoglobin. The PO2 arteriovenous differences were 51.9 +/- 7.1 torr (m +/- SEM) for Tyrode, 40.2 +/- 6.4 torr for albumin solution, 113.7 +/- 6.5 torr for non-modified hemoglobin and 132.7 +/- 6.8 torr for dex-BTC-Hb. Compared to albumin and Tyrode solutions, hemoglobin solutions transferred more oxygen to tissues. The desaturation of dex-BTC-Hb was significantly superior (p < 0.05) to the one non-modified hemoglobin. With Hb solutions, this desaturation increased with time and it depended on the perfusion flow. The structure of jejunal villi when perfused with a hemoglobin solution, remained almost normal and the loop was still active. Nevertheless, non-modified hemoglobin leaked from the vessels to the lumen and caused edema and a rupture of overlapping epithelium at the tip of the villi. With dex-BTC-Hb, such histological modifications were less significant. With albumin and Tyrode, all villi were totally necrosed and the loop was completely inert. We have demonstrated that dextran-benzene-tetracarboxylate hemoglobin had the ability to maintain the tissue alive thanks to its good capacity to release oxygen and its satisfactory vascular persistence. Dex-BTC-Hb solution can answer to needs of tissue.

Animals↗
PubMed1995

[Evaluation of hemoglobin dextran 10-benzene-tetracarboxylate, oxygen transporters, using a model of guinea pig intestine].

With the aim of assessing of dextran-benzene-tetracarboxylate hemoglobin as an oxygen carrier, we studied histological changes in the intestinal loop. The intestinal tissue being very sensitive to hypoxia, in the anesthetized guinea pig, an innervated loop was vascularly perfused with open-flow during one hour at zero hematocrit. To estimate the capacity of hemoglobin solution to oxygenate this tissue, we observed the mechanical and histological changes in the organ and the arterio-venous difference in PO2, oxyhemoglobin, deoxyhemoglobin and we compared them with human albumin, Tyrode and non-modified hemoglobin. The PO2 arterio-venous differences were 51.9 +/- 7.1 torr (m +/- SEM) for Tyrode, 40.2 +/- 6.4 torr for albumin solution, 113.7 +/- 6.5 torr for non-modified hemoglobin and 123.1 +/- 7.9 torr for dex-BTC-Hb. Compared to albumin and Tyrode solutions, hemoglobin solutions transferred more oxygen to tissues. The desaturation of dex-BTC-Hb was significantly superior (p < 0.05) to the one non-modified hemoglobin. The structure of jejunal villi when perfused with a hemoglobin solution, remained almost normal and the loop was still active. Nevertheless, non-modified hemoglobin leaked from the vessels to the lumen and caused oedema and a rupture of overlapping epithelium at the tip of the villi. With dex-BTC-Hb, such histological modifications were less significant. With albumin and Tyrode, all villi were totally necrosed and the loop was completely inert. We have demonstrated that dextran-benzene-tetracarboxylate hemoglobin had the ability to maintain the tissue alive thank to its good capacity to release oxygen and its satisfactory vascular persistence.

Animals↗
PubMed1995

Study of the vesicles released during conservation of red cells.

The purpose of this study was to determine the protein composition of the vesicles released from senescent erythrocytes and its variation during their experimental conservation at +4 degrees C in citrate phosphate dextrose (CPD), over a period of 8 weeks. Techniques employed included electron microscopy, SDS-PAGE and immunoblotting. Electron microscopic observation of senescent erythrocytes showed the simultaneous release of one or several vesicles of varying size and shape, while close examination of individual vesicles revealed a slack membrane structure and the presence of band 3 protein. SDS-PAGE and immunoblotting showed the vesicles to be composed mainly of band 3 and its breakdown products and to be lacking in spectrin. Use of specific antibodies demonstrated the presence of free haemoglobin, immunoglobulin G (IgG) and fragment C3b of complement. During conservation for 8 weeks, the concentration of band 3 protein decreased, while the concentrations of IgG and C3b increased and there was no apparent variation in haemoglobin levels.

Complement C3↗
PubMed1995

Chronology of the formation of vesicles and membrane protein aggregates during erythrocyte aging.

The aim of the present work was to study the changes undergone by proteins in ghost cells, vesicles and membrane protein aggregates during erythrocyte aging. As a model of cell, whole blood collected into CPD was stored for eight weeks at +4 degrees C. SDS-PAGE and immunoblotting with antibodies against spectrin and band 3 showed that vesicles were mainly composed of band 3 and were devoid of spectrin, whereas membrane protein aggregates contained several membrane proteins but in a more advanced state of degradation. A study of spectrin and band 3 in the ghosts, vesicles and protein aggregates revealed increasing fragmentation of both proteins with storage time. Since this degradation was most important in membrane protein aggregates, it was possible to establish the chronological order of appearance of vesicles and aggregates. In view of our observations, we propose that membrane protein aggregates may be regarded as replacement structures resulting from membrane rearrangements occurring after the emission of vesicles.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1994

Human hemoglobin conjugated to carboxylate dextran as a potential red blood cell substitute. II--Pharmacotoxicological evaluation.

A solution of human hemoglobin bound to benzene tetracarboxylate substituted dextran, whose physicochemical characteristics are defined in part I, was evaluated in vivo as a potential red blood cell substitute. Further experiments show: - the confirmation of a lack of acute toxicity in mice and guinea pigs after injection of 12.5%, 25% and 50% of the blood mass and the absence of death in rabbits having undergone three successive 25% hemorrhagic shocks in three week intervals. A plasma half-life of 9.5 +/- 0.5 hours in 70-75% hemorrhagic shocks on guinea pigs and the absence of dex-BTC-Hb in thoracic and abdominal cavities. No tissue oedema was noticed. Total hemoglobinuria did not exceed 10% of the injected hemoglobin quantity and only involved free hemoglobin. A lack of death in 70-75% hemorrhagic shocks and survival times ranging from 10 hours to 3 days in total exchange transfusions in guinea pig experiments.

Animals↗
PubMed1994

Methemoglobin formation after administration of hemoglobin conjugated to carboxylate dextran in guinea pigs. Attempts to prevent the oxidation of hemoglobin.

In 1990, McGown demonstrated in vitro a limitation of extracellular methemoglobin (metHb) formation by releasing and recycling of ascorbic acid by red blood cells. In order to investigate the autoxidation of free or modified hemoglobin in plasma and the possibility of reproducing McGown's phenomenon in vivo, we performed a 50% blood mass exchange in guinea-pigs with a 70 +/- 5 g/l dex-BTC-Hb solution (metHb < 5%). Methemoglobin was determined according to Evelyn-Malloy's method. We observed a clear but limited oxidation of plasmatic hemoglobin (MetHb approximately 30-40% at t = 12 hrs up to t = 24 hrs). A similar blood mass exchange was performed with the same hemoglobin solution which was previously totally oxidized into metHb. 40% of this methemoglobin was found to be reduced after 12 hrs. These results demonstrated a marked reducing activity by residual blood as shown by others. The addition of potentially protective compounds such as ascorbic acid (non enzymatic intraerythrocytar reduction pathway), methylene blue or riboflavin (enzymatic intraerythrocytar pathway), allowed a significant drop in the methemoglobin level. On the contrary, we didn't observe any reducing effect with reduced glutathione.

Animals↗
PubMed1994

Preparation and characterisation of poly(lactic acid) hemoglobin microspheres.

For many years, a lot of research effort has been carried out with a view to preparing blood substitutes. Our group has developed a process of encapsulation of hemoglobin in polylactid microspheres. An aqueous solution of hemoglobin was emulsified into a solution of polymer in methylene chloride to form a W/O emulsion. This primary emulsion was then added to a external aqueous phase under stirring until the evaporation of methylene chloride. The microspheres were separated by filtration and washed with distilled water. Microspheres were spherical and their sizes vary between 10 and 500 microns. More than 80% of the hemoglobin was encapsulated. From the absorption spectra of hemoglobin from microspheres, we did not notice any alteration of the oxygen carrier. The dissociation curve of the hemoglobin demonstrated the permeability of the polymeric wall of these microspheres to oxygen. This curve was relatively sigmoidal and presented a P50 similar to that of free hemoglobin in the same experimental conditions. A cellulose's acetate gel electrophoresis of hemoglobin extracted from the microspheres showed one band that correlates with intact hemoglobin. These results suggest that hemoglobin does not interact chemically with the polymer matrix and that the process of microencapsulation does not alter the hemoglobin molecule.

Blood Substitutes↗
PubMed1993

Antiproliferative activity of thermosensitive liposome-encapsulated doxorubicin combined with 43 degrees C hyperthermia in sensitive and multidrug-resistant MCF-7 cells.

Thermosensitive liposome-encapsulated doxorubicin (TLED) was compared to free doxorubicin, at 37 degrees C or combined with 43 degrees C hyperthermia, in sensitive and multidrug-resistant MCF-7 human tumour cells using clonogenic assays. In the resistant subline, TLED was found to partly circumvent multidrug resistance (MDR). The reversal was comparable to that obtained when verapamil was added to free doxorubicin. When hyperthermic treatment was applied, no difference in thermosensitivity was found between sensitive and resistant cells. The combination of hyperthermia with free doxorubicin did not reverse MDR. Hyperthermia and TLED yielded additive effects in the resistant cells while potentiation was observed in the sensitive cells. These results confirmed the usefulness of the liposome encapsulation of doxorubicin in reversing MDR. The possibility of obtaining additive cytotoxicity using TLED combined with hyperthermia may represent an alternative way of intensification of doxorubicin cytotoxicity concomitant with the circumvention of MDR without using MDR reversing agents, which often generate limiting toxic side-effects.

Adenocarcinoma↗
PubMed1993

[Extracted hemoglobins as oxygen transporters: proposal of a hemoglobin-dextran-benzenetetracarboxylate conjugate].

The implication of blood in HIV and other viruses transmission has invigorated the research for finding a fluid able to replace blood as regards its oxygen-carrying properties. In this work, the specifications of a potential substitute are first defined. Then, the means to be developed in order to match these specifications at best are precise. Afterwards, a possible oxygen-carrier, the hemoglobin-dextran-BTC conjugate, is described.

Benzoates↗
PubMed1993

Influence of heparin on the chemotactic activity of human thrombin.

Chemoattractant properties of human thrombin have been studied, by polymorphonuclear leucocyte migration under agarose gel, in the presence of various sulphated macromolecules such as standard heparins, low molecular weight heparins, CY216, K2165, PK10169 and pentosane polysulphate. These compounds did not attract polymorphonuclear leucocytes within the range of concentrations used, whilst thrombin alone is a cytotaxin for these cells. Addition of heparins to thrombin led to an increase in the chemoattractant activity of this enzyme for at least one of the doses studied. Augmentation of the chemoattractant activity of thrombin by heparins was shown at concentrations equivalent to those found in-vivo after administration of therapeutic doses of heparin. Pentosane polysulphate, at the studied concentrations, did not lead to a significant rise in the chemoattractant activity of thrombin.

Chemotaxis, Leukocyte↗
PubMed1992

A potential blood substitute from carboxylic dextran and oxyhemoglobin. I. Preparation, purification and characterization.

Human adult hemoglobin (Hb) from peripheral venous blood was covalently linked, under its oxygenated form, to a dextran polymeric effector to yield conjugates with low oxygen affinity. The polymeric effector was synthesized by directly coupling benzene tetracarboxylic anhydride to dextran (MW approximately 10,000) under mild conditions. The reaction parameters were chosen so that the resulting polymeric derivative was only very little cross-linked and possessed benzene tricarboxylate site concentrations lesser than 1 site for 10 glucose units, as it was found that for higher concentrations the polymer exhibited anticlotting properties. The reaction between oxyHb and the polymer (dex-BTC) was carried out in water in the presence of a water-soluble carbodiimide (EDCI). By optimization of the reaction conditions, a dextran-Hb conjugate with a P50 of 21 torr (37 degrees C, 50mM Bis-tris buffer pH 7.4, 0.14M NaCl, 40 mM glucose) and a potential O2 release of 0.30 ml/g Hb between oxygen partial pressures of 100 and 40 torr, was obtained. The viscosity and oncotic pressure of a solution containing about 6% of conjugated Hb were respectively 1.8 cSt (37 degrees C) and 28 torr (25 degrees C). This solution could be stored frozen at -20 degrees C for a long time, without modification of its properties.

Benzoates↗
PubMed1992

Possible importance of chromatographic purification position in a blood substitute elaboration process.

Purification of hemoglobin (Hb) solutions suggested as oxygen carriers is an imperative necessity. All processes currently used clear out the solutions of almost the totality of impurities that are able to negatively influence the transfusional efficiency of Hb. We have studied the stability (metHb measurement) of Hb purified by DEAE dextran chromatography (Spherodex, 10 mM phosphate buffer, pH 7.20) which eliminates lipopolysaccharides, enzymes and non heminic-proteins ... without denaturing Hb. In spite of the improvements due to this purification method on the transfusional efficiency of non modified Hb solutions, the lack of enzymes involved in the protection of Hb against autooxidation (superoxide dismutase, peroxidase, catalase ...) makes it much more vulnerable to the reagents used during the following chemical processes: pyridoxylation, polymerization or macromolecule binding, thereby leading to an important oxidation to metHb. These observations led us to question the optimal position of purification in a process of modified Hb preparation. We have shown the importance of this chromatographic position in working on pyridoxylated Hb bound to monomethoxypolyoxyethylene. Spherodex chromatography appears to be a very satisfactory purification method, provided it occurs only at the last step of the process. Many authors have not been attentive to this phenomenon which could be found with other Hb modifications. This therefore imposes to study the best place to incorporate a particular purification step into a hemoglobin preparatory procedure.

Blood Substitutes↗
PubMed1992

A potential blood substitute from carboxylic dextran and oxyhemoglobin. II. Physicochemical and physiological assessments. Preliminary results on guinea pig.

The hemoglobin solution covalently linked to dextran benzene tetracarboxylate (dex-BTC) described in Part I, offered the following characteristics: [Hb] = 70 g/l, non modified Hb less than 15%, metHb less than 5%, P50 close to blood value, viscosity and oncotic pressure near to physiological values (37 degrees C). It was biocompatible, stable in plasma, non hypotensive in rat model, non pyrogenic and did not present abnormal toxicity (on mice, according to the french Pharmacopea). Nevertheless, on account of the presence of dextran in the conjugate and due to the literature, we observed an anaphylactoïd reaction in rats consecutive to the injections: absence of hypotension but presence of a massive oedema resulting from an important increase in the capillary permeability with harmful consequences to the vascular retention and survival time. As guinea pigs are insensitive to dextran, we are beginning to assess this conjugate solution in this animal. The first results are very promising: a lack of mortality after large injection, an almost complete vascular retention, a weak urinary loss (only non conjugated Hb), and a plasmatic half-disappearance time close to 7h. Results from haemorrhagic shocks to a final hematocrit less than 0.10 l/l and total and isovolemic exchange transfusions seem to prove a real oxygen-carrying capacity of this new Hb solution.

Animals↗
PubMed1992

A potential blood substitute from carboxylic dextran and oxyhemoglobin. III. Evaluations by perfusion of normal and ischemic guinea-pig heart.

Hemodynamic parameters of six groups of guinea-pig hearts were studied by the working heart technic of Neely. Three groups were respectively perfused with: Krebs-Henseleit, purified native hemoglobin 1gm/dl and hemoglobin conjugated to dextran benzene tetracarboxylate 1 gm/dl. Three other groups were perfused under the same conditions except that after 30 mn of perfusion, 10 mn of total ischemia were produced followed by 30 mn of reperfusion with the previous solutions. All solutions contained 10 g/l of BSA. Hearts perfused with Hb solutions without ischemia or after ischemia show better parameters than with Krebs-Henseleit. These observations suggest that contrary to previously published results, purified Hb and more, dextran-BTC-Hb appear to be perfusable and are less deleterious for heart than saline without hemoglobin.

Animals↗
PubMed1992

Serum and erythrocyte ferritin in regular blood donors.

This study evaluated 217 regular blood donors, with the aim of measuring their iron stores and recording the influence of donation frequency. In the population studied, 10% of men and 15% of women showed reduced iron stores of the erythropoietic marrow (erythrocyte ferritin less than the normal range) and 64% of the population showed a latent deficiency in iron (serum ferritin values less than the reference values). An increase in donation frequency was followed by an important decrease in serum ferritin concentration. Blood haemoglobin levels were inferior to control limits in 4% of men and 15% of women, measurements of haemoglobin being the legal screening test performed at the time of donation. However, this test gives a late indication of an already established iron deficiency and should be replaced by the determination of serum ferritin in order to avoid the possible appearance of iron deficiency. Erythrocyte ferritin is another late indicator of iron depletion and hence is of little interest for the control of blood donors.

Adult↗