Search PubMed⌕ Search

Biomedical subjects

T Burnouf

Publications and source records attributed to T Burnouf.

50 records · Page 3Linked to original sources
PubMed1992

A pasteurized therapeutic plasma.

A process to subject pooled human plasma to a viral inactivation treatment by heating in the liquid state for 10 hrs at 60 degrees C (pasteurization) has been designed and evaluated. Activity recovered from clotting factors and protease inhibitors exceeded 80%. Overall clotting activity remained good. No activation of coagulation factors was detected. The process did not generate aggregates. No side effects (toxicity, hypotension, variation in heart rate, thrombogenicity) could be detected in animal models. Virus kill studies, using 7 lipid-enveloped and non-enveloped viruses including HIV-1 and Sindbis virus, revealed inactivation levels similar to those obtained for plasma derivatives. Thus, pasteurisation of human plasma can be achieved in conditions that allow good recovery of biological properties while ensuring a high degree of inactivation of lipid-enveloped and non-enveloped viruses.

Blood Banks↗
PubMed1991

Comparison of high purity factor IX concentrates and a prothrombin complex concentrate in a canine model of thrombogenicity.

A non-stasis canine model of thrombogenicity has been used to evaluate batches of high purity factor IX concentrates from 4 manufacturers and a conventional prothrombin complex concentrate (PCC). Platelets, activated partial thromboplastin time (APTT), fibrinogen, fibrin(ogen) degradation products and fibrinopeptide A (FPA) were monitored before and after infusion of concentrate. Changes in FPA were found to be the most sensitive and reproducible indicator of thrombogenicity after infusion of batches of the PCC at doses of between 60 and 180 IU/kg, with a dose related delayed increase in FPA occurring. Total FPA generated after 100-120 IU/kg of 3 batches of PCC over the 3 h time course was 9-12 times that generated after albumin infusion. In contrast the amounts of FPA generated after 200 IU/kg of the 4 high purity factor IX products were in all cases similar to albumin infusion. It was noted that some batches of high purity concentrates had short NAPTTs indicating that current in vitro tests for potential thrombogenicity may be misleading in predicting the effects of these concentrates in vivo.

Animals↗
PubMed1991

A highly purified factor VIII:c concentrate prepared from cryoprecipitate by ion-exchange chromatography.

A new ion-exchange chromatographic procedure has been developed to produce a highly purified factor VIII (FVIII) concentrate from plasma cryoprecipitate. Solubilized cryoprecipitate, after adsorption on aluminium hydroxide and cold precipitation, was treated with 0.3% tri(n-butyl)phosphate and 1% Tween 80 at 25 degrees C for at least 8 h to inactivate lipid-enveloped viruses. The fraction was then loaded onto a column packed with DEAE-Fractogel TSK 650 M and chromatographed. Most proteins and TnBP-Tween 80 flowed through the gel unretarded. FVIII:c, which bound to the gel, was eluted by increasing the ionic strength, then was directly filter-sterilized without ultrafiltration or addition of a protein stabilizer. Chromatographic recovery of FVIII:c was 80-90%. After freeze-drying, FVIII:c was at a concentration of 42.5 +/- 9.5 IU/ml and had a specific activity of 175.4 +/- 37.8 IU/mg (n = 40), corresponding to a purification factor of over 12,000 from plasma. The typical yield of the freeze-dried FVIII:c from cryoprecipitate was 55-65%. FVIII:c was stable for over 24 h at room temperature in the liquid state. The mean content of fibrinogen and immunoglobulin G was only 65 and 100 mg/l, respectively, corresponding to 1.4 and 2.3 mg/1,000 IU FVIII:c. This concentrate, which is much purer than traditional FVIII concentrates, has been found to be well tolerated and effective in clinical treatment of hemophilia A patients.

Adsorption↗
PubMed1991

Parasitologic and clinical human response to immunoglobulin administration in falciparum malaria.

The protective effect of African IgG antibodies against Plasmodium falciparum malaria was investigated by passive transfer in Thai patients. Sera from 333 African adults were collected in the Cote d'Ivoire and subjected to extensive screening. One hundred fifty-three samples were discarded for safety reasons, and IgG was extracted from those remaining under conditions allowing their use by the intravenous (iv) route. Eight Thai patients with P. falciparum parasitemia were treated by iv inoculation of the IgG: six with a 100 mg/kg dose given over three days, one with a single 20 mg/kg dose, and one with a single 200 mg/kg dose. To ensure a safety margin of at least 48 hours, subjects were chosen among patients having a recrudescent parasitemia following quinine treatment failure at the RI level. At that stage, symptoms were mild or absent and parasitemia was low but increasing (range 4, 200-9,000/microliters). The IgG pool exerted a profound, stage-specific, but non-sterilizing effect on each of the strains tested, and proved to be safe. Asexual parasitemia decreased by a mean 728-fold (range 46-1,086), while gametocytes were unaffected. Clearance of parasites and symptoms was as fast or faster than with drugs, and was consistent in the eight patients treated, suggesting that target antigens were equally expressed in geographically remote isolates. In peripheral blood smears, no mature forms were seen at any time during the followup, which does not support the hypothesis that reversal of cytoadherence occurred. After the disappearance of the transferred antibodies, recrudescent parasites from three patients were found to be susceptible to the same extent (mean decrease of 1,310-fold) to the same IgG preparation, indicating that selection of parasites able to escape the effect of antibodies had not occurred. No adverse side-effects were detected during the followup, which lasted one year.

Adult↗
PubMed1991

[Use of a biological glue in partial pulmonary excision surgery. Results of a controlled trial in 50 patients].

A controlled study concerning the surgical use of a fibrin glue was conducted in 50 patients undergoing partial pulmonary excision. In 25 of these patients, chosen at random, hemostasis and aerostasis of the fissural, and/or intersegmentary dissection planes were achieved by electrocoagulation, in the other 25 by the application of fibrin glue. The statistical study did not show any significant difference between the two groups in terms of the surgical indication, the type of excision and the associated surgical procedures (pleurectomy and parietectomy). No significant statistical difference was observed concerning the quality of aerostasis, the post-operative drainage, the persistance of residual collection or faulty reexpansion after removal of the latter, and the necessity for repeated drainage. The same applied to the length of post-operative hospital stay. This study seems to demonstrate that the surgical application of fibrin glue on the fissural and/or intersegmentary dissection planes is feasible but, as compared to electrocoagulation, does not significantly improve the quality of the surgical results for partial pulmonary excision; however its use could reduce the duration of post-operative drainage.

Adolescent↗
PubMed1990

Biochemical and physical properties of a solvent-detergent-treated fibrin glue.

A fibrin glue preparation has been obtained from pooled human plasma using a procedure which includes a solvent-detergent (SD) treatment to inactivate lipid-enveloped viruses. The SD treatment inactivated greater than or equal to 5.5 log10 of HIV in less than 45 min, and greater than or equal to 5 log10 and greater than or equal to 6.5 log10 of VSV and Sindbis virus, respectively, in less than 2 h. The product was found to contain high quantities of fibrinogen (116 +/- 2.49 g/l; n = 12), factor XIII (35 +/- 2.88 U/ml) and von Willebrand factor (23 +/- 1.9 U/ml ristocetin cofactor activity), and relatively low levels of fibronectin (5.9 +/- 0.51 g/l). Plasminogen, the precursor of plasmin, which may play a negative role by decreasing the resistance of the fibrin clot, was at only 0.03 g/l. Cellulose acetate electrophoresis showed 95% gamma-proteins and 5% alpha-2-beta proteins. Sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions detected three main protein bands with apparent molecular weights of 65, 56 and 47 kilodaltons, probably corresponding to the alpha, beta, and gamma fibrinogen subunits. Other characteristics of the product included (1) high clottability of fibrinogen (over 85%); (2) absence of low molecular weight fibrin degradation products; (3) rapid solubilization at room temperature (less than 10 min); (4) high tensile strength (202 +/- 27 g/cm2 after 2 h of application), and (5) high elasticity of the fibrin clot. In addition, scanning electron microscopy revealed a highly organized structure showing tridimensional arrangement of the fibrin fibers. SD treated fibrin glue should efficiently replace autologous fibrinogen or cryoprecipitate preparations for surgical application.

Antiviral Agents↗
PubMed1989

Properties of a highly purified human plasma factor IX:c therapeutic concentrate prepared by conventional chromatography.

We have characterized a highly purified (HP) factor IX concentrate intended for therapy of hemophilia B. The product has been prepared from pooled human plasma using a large-scale procedure combining three conventional chromatographic steps based on DEAE ion exchange and affinity on immobilized heparin. The specific activity of the product was 119 +/- 10 IU factor IX:c/mg protein (n = 15), corresponding to a purification factor of about 9,000. The concentrate was free of the vitamin K-dependent clotting factors II, VII and X and of proteins C and S. Most of the contaminants found in factor IX complex concentrate (PCC) were absent in this new product. High-molecular-weight kininogen, factors VIII, XI, XII or prekallikrein were not detected. There were no activated factors, such as factors IXa, and Xa, no thrombin and no phospholipids. Only two contaminants could be detected: C4 and inter-alpha-trypsin inhibitor (about 0.8 and 1.2 mg/1,000 IU factor IX:c, respectively). The purity of the product, as compared to PCC, was confirmed by sodium dodecylsulfate polyacrylamide gel electrophoresis, cellulose acetate electrophoresis, Grabar-Williams immunoelectrophoresis, and bidimensional immunoelectrophoresis. Thrombogenicity tests in rabbits revealed that the HP factor IX tested had a lower thrombogenic power than the PCC tested. The concentrate has been subjected to a 0.3% tri(n-butyl) phosphate-1% Tween 80 treatment for 6h at 25 degrees C during its production to reduce or eliminate the risk of transmission of plasma-borne lipid-enveloped viruses. These conditions inactivated more than 3.8 log10 of vesicular stomatitis virus and more than 4.3 log10 of sindbis virus within 1 and 2 h of treatment, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Factors↗
PubMed1988

Large-scale production and properties of a solvent-detergent-treated factor IX concentrate from human plasma.

A human solvent-detergent (SD)-treated factor IX concentrate has been produced from cryoprecipitate-poor plasma using DEAE-Sepharose CL-6B and heparin-Sepharose CL-6B chromatography. The DEAE eluate was incubated with an SD mixture [0.3% tri(n-butyl) phosphate-1% Tween 80, 6-h at 24 degrees C] which was found to inactivate, in less than 1 h, more than 3.8 log10 of vesicular stomatitis virus and more than 4.8 log10 of Sindbis virus; the SD was removed by a subsequent heparin adsorption step. The specific activity of the concentrate was 10.9 +/- 1.3 IU factor IX: c/mg protein (n = 15). The factor IX coagulant to antigen ratio was 0.7 +/- 0.1. The concentrate was essentially free of factors II, VII and X, and protein C. The usual major contaminants of prothrombin complex concentrate (PCC) were absent: the concentrate contained about 94% alpha-1 proteins, and only 4 major proteins were resolved by SDS-PAGE (respective apparent molecular weight: 130, 86, 76 and 69 kilodaltons), and by crossed immunoelectrophoresis against an anti-PCC serum. The nonactivated partial thromboplastin time was equivalent to that of PCC; the product was devoid of factor IXa, of other activated procoagulant factors and of coagulant-active phospholipids (removed with SD in the heparin breakthrough fraction). Animal studies using the Wessler test and acute-toxicity test in rabbits revealed no adverse side effects. SD treatment could thus be used to inactivate viruses in factor IX concentrate and improve the safety of replacement therapy in hemophilia B.

Adsorption↗
PubMed1987

Biochemical and biological properties of an alpha 1-antitrypsin concentrate.

alpha 1-Antitrypsin (AAT) has been purified from human plasma supernatant A (equivalent to COHN fraction II + III) by a large-scale chromatographic procedure involving anion-exchange adsorption on DEAE Sepharose CL-6B fast flow and size-exclusion chromatography on Sephacryl S-200. Before freeze-drying, the liquid concentrate was heat-treated at 60 degrees C for 10 h to reduce the risk of transmission of blood-born viral diseases. Using this procedure, AAT is recovered with 80-90% purity in 65-75% yield from supernatant A. The heterogeneity of AAT is preserved across the purification steps. In addition, purified AAT exhibits inhibitory activities against trypsin and elastase equivalent to that of the serum protein. The mean association rate constant for elastase was found as high as 2.15 X 10(5) M-1 s-1. Thus, purifying active AAT from supernatant A contributes to improving the availability of this protein which may be potentially useful in the treatment of hereditary emphysema.

Chromatography, DEAE-Cellulose↗
PubMed1987

Large scale chromatographic purification of alpha 1-antitrypsin from human plasma supernatant II + III.

We describe a large-scale chromatographic method to purify alpha 1-antitrypsin (AAT) from human plasma supernatant II + III. Supernatant II + III was injected onto DEAE sepharose CL 6B to get an albumin-rich fraction as well as a fraction that contained about 45% AAT. This intermediate purity AAT fraction was further purified by size-exclusion chromatography on Sephacryl S-200. The product was heated in solution at 60 degrees C for 10 hours in the presence of a stabilizer to lower the risk of transmission of viral diseases. Purity of the AAT concentrate is over 85%; clinical testing of its safety and efficacy in the treatment of PiZ patients is underway.

Blood Proteins↗
PubMed1987

[Virus inactivation in plasma fractions for therapeutic use].

Methods to inactivate (or eliminate) viruses must be developed to ensure the safety of blood plasma fractions. For that purpose, dry or liquid heat treatment, solvent/detergent mixtures, beta-propiolactone/ultraviolet treatment, and chromatographic methods are the main procedures in use to date.

Blood↗
PubMed1981

[Valve of a freeze-dried gelatin-agarose combination in selective extraction of fibronectin from human plasma].

We report here a simple procedure for the isolation of human plasma fibronectin by affinity adsorption on a new lyophilized adsorbent which is obtained by mixing and polymerizing agarose with gelatin. This method permits to obtain fibronectin and a fibronectin-depleted plasma without dilution. The yield of fibronectin is about 20 to 25 per cent. Fibronectin was identified by cross-reactions against specific antibodies. Its purity (greater than or equal to 99 per cent) was controlled by immunoelectrophoresis and SDS-PAGE. Furthermore, its biological activity was demonstrated by a spreading test performed on BHK cells. Such a test can be used to determine the specific activity of extracted fibronectin considering that the number of spread cells placed in presence of exogenous fibronectin (5 microgram/ml of culture medium) was 4.5 to 5 fold-superior to the control, after 30 minutes of incubation at 37 degrees C.

Antibody Specificity↗
PubMedDate not supplied

A therapeutic, highly purified factor XI concentrate from human plasma.

A highly purified factor XI (FXI) concentrate was prepared from human plasma by a process comprising a filter adsorption step and chromatography on a cation exchange resin. The freeze-dried FXI, which solubilized quickly, had high specific activity (130-150 U/mg protein), high potency (approx. 100 U/mL), and excellent stability for at least 24 hours at room temperature in the liquid state. The overall recovery was about 220 U of FXI per liter of plasma. Minor protein contaminants (C1-inhibitor, fibronectin, IgG, and alpha-2-macroglobulin) were found to be between 0.13 and 0.46 mg per 1000 U of FXI. Fibrinogen and relevant coagulation factors (factors II, V, VII, IX, X, XII, XIII, and VIII/von Willebrand factor) were undetectable, as evidenced by immunologic and immunoelectrophoretic data. Components of the kinin system were present in trace amounts or were undetectable. No evidence of activated factors such as factors Xa and IXa was found. Proteolytic activity, as assessed by S-2288 chromogenic substrate, was negligible and thrombin was undetectable. A solvent-detergent treatment was included prior to chromatographic purification to enhance viral safety against lipid-enveloped viruses. In vitro and in vivo animal studies demonstrated the absence of thrombogenic, hypotensive, or toxic effects. No thrombogenic activity was found in the Wessler model in rabbits at doses of 900 to 1100 U of FXI per kg of body weight. This FXI preparation could be beneficial in substitution therapy of congenital or acquired FXI deficiency, especially as a way to avoid the use of fresh-frozen plasma.

Animals↗