[Evolution of techniques for preparation of labile blood products (LBP): pathogen inactivation in LBP]. / Evolution des techniques de préparation des produits sanguins labiles (PSL): inactivation des pathogènes dans les PSL.

The techniques for inactivation of pathogens in labile blood products (LBP) would appear to be the new strategy which will permit us to increase transfusion safety in the face of the risks of transmission of pathogenic agents by LBP. Various methods are in the course of development or already validated and used in France. The latter only apply however to plasma or platelet concentrates. The mechanisms of action and the efficacy of inactivation and attenuation of pathogenic agents vary with the different techniques. Each of these constitutes a preparative procedure composed of unit steps which have to be fully mastered in order to ensure the quality and transfusion efficacy of the treated product.

Melittin-phospholipid interactions: binding of the mono- and tetrameric form of this peptide, and perturbations of the thermotropic properties of bilayers.

The binding of melittin to phospholipid bilayers and micelles depends on its quaternary structure and on the state of association of lipids. Monomeric melittin only binds to lipids above their cmc, whereas tetrameric melittin exhibits a biphasic binding; the interaction with monomeric lipids being possible without dissociation of the tetramer. In lipid excess, the bound state observed by fluorescence, polarization and ORD are always very similar. We propose the following model: the presence of a lipidic interface is necessary for the binding of monomeric melittin, while the tetramer may interact with lipid monomers without any dissociation: it might increase in size by addition of lipid molecules to form a micelle-like particle. The perturbations induced by melittin on the thermotropic behaviour of charged phospholipids are detected by calorimetry (DSC) and fluorescence polarization of DPH. For the first group of lipids, constituted of mono or divalent C14 and of divalent C16 lipids, the transitions are progressively abolished in the presence of melittin, without any shift of the temperature. For a second group of lipids, essentially constituted of monovalent C16 lipids, a cooperative transition is always observed. Moreover, at lipid to protein molar ratios higher than 8, there are two distinct well-defined transitions, at the same temperature as for pure lipid and 10 degrees C to 15 degrees C lower. All these results are interpreted by a phase separation occurring between quasi-pure lipid regions and the lipid-melittin complex. These last ones either could, or not, give rise to a phase transition, according to the cohesion of the initial bilayer. In the case of binary mixtures, there would be a phase separation between enriched phosphatidylcholine regions and negative lipid-melittin complexes.

Influence of pH and ionic strength on the lysis of Micrococcus luteus cells by hen lysozyme at low (20 degree C) and high (physiological, 40 degree C) temperature.

From isoactivity curves (showing activity as a function of Ph and ionic strength) it was found that in the pH domain 6.7-8.6 frequently used in experiments involving hen lysozyme, the pH optimum of lysis of Micrococcus luteus cells at low ionic strength (0.02-0.05) by the high-temperature form (40 degree C, physiological temperature) was one to two pH units lower than that by the low-temperature form (20 degree C).

Plateletpheresis concentrates produced with the COMTEC cell separator: the French experience.

The latest generation of cell separators such as Trima (Gambro), Amicus (Baxter) and AS-TEC 204 (Fresenius), allow the collection of leucocyte-reduced platelet concentrates without secondary filtration. Fresenius has recently developed the COMTEC cell separator whose performance has been evaluated by several teams in France. This new cell separator is an improved version of the Fresenius AS-TEC 204 cell separator, designed to allow more efficient platelet collections. This study reports on the experience of six French teams (from Bordeaux, Clermont-Ferrand, Creteil, Dijon, Lille and Nancy) who obtained 696 leucocyte-reduced plateletpheresis concentrates in the course of collection using the new Fresenius COMTEC cell separator. All healthy volunteer donors fulfilled French selection criteria for platelet apheresis. Donors were eligible if they had suitable venous accesses, if their bodyweight was *50 kg and if their pre-apheresis platelet count was >150 x 10(9) l(-1). Between 4606 and 5229 ml of blood were processed. The mean volume of the platelet concentrates was between 439 and 493 ml (mean 460 +/- 63 ml). The platelet yield was of the order of 5.18 +/- 1.02 x 10(11) with only one platelet concentrate below the norm of 2 x 10(11) platelets (0.91 x 10(11)). No plausible explanation for this was found. The residual leucocyte levels conform to current norms. The platelet concentrates contained less than 1 x 10(6) leucocytes per concentrate (mean 0.233 +/- 0.150 x 10(6) leucocytes) in more than 97% of the components produced with >95% statistical confidence. The efficacy of the cell separator (52.44 +/- 7.35%) is comparable to that of other separators. The Fresenius COMTEC cell separator makes it possible to obtain leucocyte-reduced platelet concentrates which comply with current standards both in terms of platelet content and residual leucocyte level.

[Pheochromocytoma of the broad ligament]. / Phéochromocytome du ligament large.

The authors report a rare case where a pheochromocytoma which was not in the adrenal gland occurred in the broad ligament. A review of the literature resulted in only three published cases being found. When the symptomatology suggests that there may be a pheochromocytoma in the body one has to research where it is sited and one has to think of such a possibility if a tumour in the broad ligament is found during an operation, so that the risks of operating on these tumours can be lessened.

The temperature and pH-dependent transition of hen lysozyme. Characterization of two temperature-defined domains and of an N-acetylglucosamine (inhibitor)-insensitive form.

The previously described temperature and pH-dependent transition in the solid state of hen lysozyme was studied in solution. Experiment concerning the velocity of lysis of M. luteus by lysozyme and its behavior in presence of an inhibitor (GlcNAc) as well as a reinvestigation of the Arrhenius curves over a large range of pH, demonstrated the existence of two temperature-induced domains. An inhibitor-insensitive lysozyme form was characterized at 40 degrees (physiological temperature).

Quality assessment of seven types of fresh-frozen plasma leucoreduced by specific plasma filtration.

BACKGROUND AND OBJECTIVES: A study was undertaken to determine plasma quality after specific filtration. MATERIALS AND METHODS: Seven types of plasma were tested, after filtration of plasma from filtered or non-filtered whole blood. Leucocyte counting was carried out after a 30-fold concentration of the sample. Twenty-nine parameters (including coagulation testing, proteins, coagulation factors and activation markers) were measured before and after filtration, and after 6 months of storage. RESULTS: After specific plasma filtration, the average residual leucocyte counts were less than 2250/l. In spite of small statistically significant changes in proteins, coagulation factors and complement activation, this study showed that plasma filtration did not alter plasma quality. After 6 months of storage at -30 degrees C, factor VIII recovery varied between 91 and 109%. Haemostasis parameters and activation markers remained within the normal range. CONCLUSIONS: Specific plasma filtration reduced the leucocyte number to < 104 leucocytes/l. The quality of plasma was not altered by the additional step of specific plasma filtration.