Evaluation of Platelet Concentrates with the New Dideco Blood Cell Separator: Excel

The Excel Cell Separator produced by Dideco represents a good compromise between automation and Platelet efficiency. Platelet activation is a phenomenon that we can find with the concentrates of all cell separators. Although, the complement activation of Excel is extremely lower in comparison with the same data obtained using all the other cell separators, the 5-day storage is acceptable. It will be important to research the bacteriological controls. Like the pH of the platelet bags, because in certain cases it was too low. For the future it will be interesting to study the possibility to predict the quantity of platelets collected having a system that is adaptable with the donor parameters.

Study of Parameters Involved in Specific Immunoadsorption of Apolipoprotein B

A therapeutic immunoadsorption system on immobilized and anti-apolipoprotein B as a plasma cholesterol lowering procedure was optimized. Several antibodies were compared and highest adsorption capacity was obtained with goat polyclonal antibodies. Optimum quantities of antibodies to be immobilized on the gel and quantities of apo-B to be applied to columns were determined. The amount of antibodies released from immunoadsorbents can be minimized by treatment with a 0.005% glutaraldehyde solution with an acceptable reduction rate of adsorption capacity. Each phase, adsorption and desorption respectively, were well-defined and synchronized so two columns could be used in parallel in an automated procedure.

In these conditions, the immunoadsorption system can efficiently, specifically and safely remove cholesterol and has to be subjected to clinical trials.

Dengue outbreaks: a constant risk for Reunion Island. Results from a seroprevalence study among blood donors

BACKGROUND

Immunity against dengue virus (DENV) on Reunion Island could play an important role in the risk of dengue outbreaks but is rather unknown. A study was performed to estimate seroprevalence of antibodies against DENV among blood donors.

METHODS

An age- and sex-stratified sample of 1825 sera was randomly selected.

RESULTS

Overall seroprevalence was 3.1% (95% CI: 2.2-3.9%); seroprevalence increased with age and was much higher in women than in men.

CONCLUSION

The low level of herd immunity is consistent with the absence of an endemic circulation of DENV, and makes it probable that Reunion Island will face future outbreaks.

Effects of irradiation, presence of females, and sugar supply on the longevity of sterile males Aedes albopictus (Skuse) under semi-field conditions on Reunion Island

BACKGROUND

The development of the sterile insect technique (SIT) for reducing populations of Aedes albopictus (Skuse), (the vector of Chikungunya and Dengue fever), was studied in Reunion Island. For some mosquito species the sterilization process and mating activity may alter male survival. Most previous studies were carried out in the laboratory and may inadequately reflect the field situation. We conducted a semi-field experiment to evaluate the impact of sugar supply and mating activity under natural climatic conditions on wild and sterile male Ae. albopictus longevity, using large cages set up in an open clearing between trees and shrubs in Reunion Island.

RESULTS

Wild males had a mean longevity of 15.5 days in the absence of females and with an immediate sugar supply; longevity in sterile males was similar. The presence of females greatly reduced both wild and especially sterile male lifespan; however, an immediate sugar supply could counteract this effect and allow sterile males to live an average of 11.6 days.

CONCLUSION

The outcomes indicate that sugar feeding could compensate for sterilization-induced damage, and that mating activity is not deleterious for well-fed males. This study stresses the critical importance of providing suitable sugar sources prior to release during SIT programmes.

The sterile insect technique for controlling populations of Aedes albopictus (Diptera: Culicidae) on Reunion Island: mating vigour of sterilized males

Reunion Island suffers from high densities of the chikungunya and dengue vector Aedes albopictus. The sterile insect technique (SIT) offers a promising strategy for mosquito-borne diseases prevention and control. For such a strategy to be effective, sterile males need to be competitive enough to fulfil their intended function by reducing wild mosquito populations in natura. We studied the effect of irradiation on sexual maturation and mating success of males, and compared the sexual competitiveness of sterile versus wild males in the presence of wild females in semi-field conditions. For all untreated or sterile males, sexual maturation was completed within 13 to 20 h post-emergence and some males were able to inseminate females when 15 h old. In the absence of competition, untreated and sterile males were able to inseminate the same number of virgin females during 48 h, in small laboratory cages: an average of 93% of females was inseminated no matter the treatment, the age of males, and the sex ratio. Daily mating success of single sterile males followed the same pattern as for untreated ones, although they inseminated significantly fewer females after the ninth day. The competitiveness index of sterile males in semi-field conditions was only 0.14 when they were released at 1-day old, but improved to 0.53 when the release occurred after a 5-day period in laboratory conditions. In SIT simulation experiments, a 5∶1 sterile to wild male ratio allowed a two-fold reduction of the wild population’s fertility. This suggests that sterile males could be sufficiently competitive to mate with wild females within the framework of an SIT component as part of an AW-IPM programme for suppressing a wild population of Ae. albopictus in Reunion Island. It will be of interest to minimise the pre-release period in controlled conditions to ensure a good competitiveness without increasing mass rearing costs.

Nouveaux critères d’évaluation de la viabilité des hématies destinées à la transfusion

In light of recent results on the mechanism of programmed cell death of human red blood cells (RBC), the aim of the present study was to solve the enigma of the rapid clearance of transfused RBCs.

MATERIALS AND METHODS

We describe new criteria of RBC viability founded on the use of flow cytometry. They were applied, in association with the classical ones: ATP and hemolysis measurements, to RBCs stored in SAGM medium for 42 days.

RESULTS AND CONCLUSIONS

Application of an original method of flow cytometric quantitation of in vitro erythrophagocytosis showed that an important proportion of stored RBCs were phagocytized although the following classical signals for phagocytosis were absent, i.e.: desialylation, phosphatidylserine exposure in the outer leaflet of the RBC membrane, loss of CD47 receptor, an antiphagocytosis signal. In addition, ATP was still present and hemolysis was very low. This enigma was solved by the use of scanning electron microscopy, which showed the disappearance of discocytes and the presence of an important proportion of spheroechinocytes, which are the phagocytable forms of RBCs. The mechanism of this dramatic morphological transformation remains to be elucidated.

Two red blood cell units collected in SAG-M additive solution with the ALYX component collection system

The first protocol available for the new ALYX component system (Baxter Healthcare Inc.) allows automated collection of two Red Blood Cell (RBC) units from one donor. The primary objective of our evaluation was to assess donor safety, comfort and to check the quality of blood products collected. 30 procedures were performed on eligible donors according to French best donation practices. Eligibility criteria were defined in order to ensure a post donation hemoglobin concentration of 11 g/dL minimum. Pre donation ferritin level was also checked. 360 ml of absolute RBC were collected from each donor. Donors physiological parameters and haematological profile were measured immediately before and after donation. Adverse events and donors were observed during the procedure and followed daily during 5 days after donation. Hemolysis in RBC was followed until of shelf life (<0.8% on 42 days storage). The evaluation of different parameters during storage show no difference if we compare with the manual technique. The concentration of hemoglobin is good and all ou concentrates are conform. No serious adverse effects were reported during and after donation. All donors confirmed they would agree to donate 2 RBC units again with this system. We have seen a good quality of RBC products. This evaluation indicates that 2 RBC donation is feasible on the ALYX system, comfortable and safe for eligible donors.

Dendritic cell KLH loading requirements for efficient CD4+ T-cell priming and help to peptide-specific cytotoxic T-cell response, in view of potential use in cancer vaccines

This study focuses on a Keyhole Limpet Hemocyanin (KLH) adjuvant strategy to augment efficacy of dendritic cell-based vaccines that use class I-restricted peptides. Requirements for loading dendritic cells (DC) with KLH were first determined in order to optimally prime CD4(+) T cells. These KLH-loaded cells were pulsed with antigenic peptide and cultured with T cells to induce a cytotoxic T lymphocyte (CTL) response against the peptide. Such a concomitant presentation of KLH and peptide by the same DC strongly augmented the peptide-specific CTL response, as compared to the response induced by DC pulsed with the peptide alone. This adjuvant effect was more pronounced for poorly immunogenic antigens. The use of optimised peptide and KLH-loaded DC may improve the efficacy of therapeutic anti-tumour peptide vaccination.

Extracorporeal photopheresis technical aspects

Extracorporeal photochemotherapy is a monotherapy first developed by Edelson et al. in 1987. It is a therapy in which 8-methoxypsoralen (8-MOP) containing lymphocytes are exposed to a long wavelength ultraviolet radiation (UVA) in an extracorporeal system. The initial design of the treatment was based on the use of the UVAR system (Therakos) for both the collection and photoirradiation of the mononuclear cells. This machine is replaced now by XTS apparatus, which is fully automatic and has integrated the fluid logic module (the "heart" of the system). Another principle is used: the two independent steps technique. It consists in first collection of mononuclear cells by a continuous blood cell separator and secondly irradiation in an independent machine: UV-MATIC irradiator (VILBER LOURMAT). These three techniques are analyzed through numerous parameters: technical, biological, hematological data. In the future, we consider we need to precise our requirements for adequate UVA energy and 8-MOP concentration. We also have to define therapeutic dose of irradiated cells and so standardize the process.

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.

Development and evaluation of an automatic method for the study of platelet osmotic response

Study of the osmotic resistance to hypotonic medium of platelets has often been suggested as a global test to assess the viability of these cells in transfusion or to study modification during haematological pathologies. A number of authors have analysed the behaviour of platelets in hypotonic media by a variety of methods (cell count, determinations of substances released, morphology, etc.), but most studies are currently based on the so-called "Hypotonic Shock Response" test (HSR). In this study, the authors describe a new automated and reproducible apparatus, called fragilimeter, using slow dialysis to assess platelet osmotic resistance. The variations in light transmission through a platelet suspension according to ionic strength are linked to the change in cellular volume and lysis and characterise the osmotic behaviour of the cells. The results revealed the good reproducibility and sensibility of the technique. This apparatus allows also the realisation of the "HSR" test.

[New automatic test for the study of platelet response to variations in osmotic pressure: application in the evaluation of the viability of platelet concentrates]

Studying the osmotic resistance or swelling of platelets has often been suggested as a global test to assess the viability of those cells. A number of authors have also analysed the behaviour of platelets in hypotonic media by a variety of complementary methods (cell count, morphology, determinations of substances released, photometric measurement of aggregation induced by aggregating agents, etc). Most studies are currently based on the so-called "osmotic shock response" test, which measures according to time the light transmitted through platelet-rich plasma (PRP) after dilution in distilled water. In this study, the authors describe a new automated and reproducible test using slow dialysis to assess platelet osmotic resistance. The "Fragilimeter", a device initially described by the authors to characterise RBC fragility, has been adapted to the study of platelet osmotic behaviour. The variations in light transmission through a platelet suspension according to NaCl concentration are linked to the change in cellular volume and lysis and characterise the viability of the cells. The results obtained with normal platelets revealed the good reproducibility of the technique. The osmotic resistance is evaluated for two parameters: anticoagulant (citrate, EDTA) and cellular concentration. The test was applied to quality control of stored platelet concentrates for transfusion, prepared with different cell separators.

Hemorheology and therapeutic hemapheresis

Rheological parameters (plasma and blood viscosities, erythrocyte aggregation and deformability) are very relevant to a better understanding of the changes inflicted on the properties of blood in various hematological diseases (monoclonal gammopathies in particular). This study reports the measurement of rheological parameters (plasma and blood viscosity, RBC aggregation and deformability) in hematological disorders where abnormal blood properties have been described. All these diseases are treated by means of blood separators (therapeutic haemapheresis:plasma exchange, plasma processing, or erythrocyte exchange). We monitored plasma viscosity in 50 patients with monoclonal gammopathies: before and after each exchange (PE) or plasma processing (PP) sessions. Hyperviscosity was reduced in all cases after plasma exchange. Erythrocyte aggregation in gammopathies was also tested (15 multiple myelomas) treated by PE or PP, EA abnormalities and therapy-induced changes are described. EA is also modified by erythropheresis (seven sickle cell anemias). Measurement of rheological parameters are useful to the diagnosis of rheological abnormalities, as well as to assess the impact of therapeutic hemapheresis techniques like plasma exchange, plasma treatment, erythrocytapheresis.

Comparison of T cell depletion strategies from bone marrow, umbilical cord and peripheral blood using five separation systems

The development of bone marrow transplantation in mismatched or matched unrelated donor situations, the recent use of peripheral blood stem cells for allogeneic transplants, the standardization and respect of good methodology practices highlight the need to evaluate new safe methods of T cell depletion (TCD). We have performed 79 in vitro TCD using five techniques: rabbit complement cytotoxicity, CD2-CD7 immunomagnetic depletion, CD5-CD8 panning system, CD34 positive purging and counterflow centrifugation elutriation (CCE). We analyzed these different approaches with regard to the degree of T and B depletion, recovery of progenitors and NK cells. In our hands, the 5 systems evaluated showed a TCD of between 1.3 and 3 log. The CCE, immunomagnetic, complement and panning methods all give similar a TCD of around 2 log. In contrast, we obtained a TCD of approximately 3 log with CD34 positive purging. The progenitor yield was around 50% regardless of the technique used. However, the degree of B and NK cell depletion was dependent on the method: specific TCD resulted in low BCD (under 0.5 log), whereas CCE or CD34 positive purging gave a BCD of greater than 1 log. Moreover, CD34 positive selection resulted in a virtually complete elimination of NK cells. CCE was the only technique allowing isolation of the small lymphocyte population which can be useful for adoptive therapy. To obtain TCD over three logarithms, double purging techniques are necessary. Because specific roles of T cells subsets in engraftment, graft versus host disease, Epstein Barr virus associated B cell lymphoproliferative disorders and disease relapse have not yet been completely elucidated, new techniques such as CD34 positive purging and double purging methods (positive and negative purging) need to be clinically evaluated, especially with respect to peripheral blood stem cells.

Treatment of graft versus host disease (GVHD) by photopheresis?

Graft versus host disease (GVHD), whether acute or chronic, is a frightening complication of bone marrow allografts-indeed in many cases it can be life threatening. In chronic GVHD, the symptoms are less serious, but they can nevertheless be alarming. The mechanism of this reaction is very complex and the pathogenesis of chronic GVHD seems to be slightly different from that of acute GVHD. However, there is no doubt about the immune mechanisms. The production of numerous cytokines plays an important part and has also been des-cribed. Until the use of photopheresis, the only treatments that were effective to any degree have been immunosuppressive treatments. Extracorporeal photopheresis (ECP), a technique recently proposed in chronic GVHD, is promising and is believed to attack the actual cause of the disease (the role of cytotoxic T lymphocytes is now recognized). ECP is believed to have a complex mechanism of action, the explanation of an anti-T lymphocyte action of ECP seems too simple. We report the results of three patients suffering from chronic GVHD, refractory to the usual treatments. The schedule for ECP was a cycle of two treatments every 2 weeks. We recorded a complete remission for patient No. 1 (grade 1) with no relapse for now 3 years. In patient No. 2 (grade 2-3) a progressive improvement was observed in the various symptoms with, however, several episodes of aggravation. In patient No. 3 (grade 2-3), the skin symptoms improved and the lichen planus lesions healed after only 15 months of treatment (interrupted by two infectious episodes during which ECP was stopped). Although the study population was small, we may be justified in thinking that ECP can cause an improvement in chronic GVHD refractory to immunosuppressive treatment. These results should be confirmed by a rigorously designed multicentre study.

The storage quality of apheresis platelets--analysis of results from seven different cell separators

Apheresis platelet concentrates (CAP) have been available for more than 20 years. Now, as a result of the use of, and progress in, automatic blood separation techniques, the quality of platelets is continually being improved so that we currently have access to purified concentrates which are not contaminated by red cells and contain only very few white cells. In view of the wide experience available to us, it was useful to monitor a number of qualitative parameters indicating platelet activation during storage. We monitored platelet aggregation, release of beta thromboglobulin, activation of complement and other basic parameters in seven platelet concentrates from seven cell separators (Cobe Spectra, MCS Haemonetics, CS3000+, Baxter, Excel Dideco, Autopheresis C Baxter, and V50 Haemonetics). We found that in the majority of cases aggregation was greatly reduced during storage. Release of beta thromboglobulin and activation of complement increased. pH remained within acceptable limits in some cases. However, in others (MCS, Excel), a decrease in pH < 6.0 was found. To conclude, although CAP, which are from a single donor, reduce the risks of transfusion, they are not protected from physical alteration and therefore from reduction in the clinical effects of transfusion. It is therefore necessary to improve the storage conditions of these cells in the future, for example by designing new plastics, or adding platelet storage media. Basic biological parameters should also be defined, within the framework of quality assurance, to evaluate platelet quality.

[Erythrocyte concentrates]

Among the blood products distributed by blood banks red cell concentrates are mostly prescribed, for treating anaemia. We now have a relatively large choice of specially prepared red cell concentrates, which enables us to satisfy more accurately each patient's particular requirements. In order to select the best suited and safest product, the risk associated with the patient's disease as well as the side effects of red cell transfusion should be evaluated.

[Concentration of platelets from apheresis: methods of preparation]

Apheresis platelet concentrates are platelet suspension obtained by apheresis from a blood cell separator. These techniques are now 20 years old. They are best way to collect great quantities of platelets from only one donor. These blood cell separators (discontinuous or continuous flow), realise extracorporeal circuit in which the blood in mixed with an anticoagulant (mainly citrate). All the procedures used are automatic and adapted with the donor parameters. The platelet donor is between 18 and 60 years old and can give 5 times per year. The platelet concentration in the product is divided into 3 classes (1 = 2 - 4 x 10(11) - 2 = 4 - 6 x 10(11) - 3 > 6 x 10(11)). Each category has a special price. Actually, we can store these platelets only 5 days. In the future, we need new studies and new directions (additive solution, new plastic) to propose a better viability and a longer storage.

Evaluation of platelet concentrates with the new Dideco blood cell separator: Excel

The Excel Cell Separator produced by Dideco represents a good compromise between automation and Platelet efficiency. Platelet activation is a phenomenon that we can find with the concentrates of all cell separators. Although, the complement activation of Excel is extremely lower in comparison with the same data obtained using all the other cell separators, the 5-day storage is acceptable. It will be important to research the bacteriological controls. Like the pH of the platelet bags, because in certain cases it was too low. For the future it will be interesting to study the possibility to predict the quantity of platelets collected having a system that is adaptable with the donor parameters.

Mechanism for the recruitment of macrophages to cancer site. In vivo concentration gradient of monocyte chemotactic activity

BACKGROUND

Tumor stroma is characterized by the development of new blood vessels, an inflammatory cell infiltration, and a fibrotic reaction. The inflammatory component of tumor stroma plays an important role in the modulation of tumor expansion. In this respect, macrophages constitute a major part of the inflammatory cell infiltration and can exert cytotoxic activity against tumor cells. The accumulation of macrophages in the vicinity of the tumor suggests their recruitment from circulating blood monocytes through the local release of chemotactic factors for monocytes.

METHODS

To detect the existence of a concentration gradient of monocyte chemotactic activity (MCA) between the tumor vicinity and blood vessels, malignant pleural effusions defined by the local presence of cancer cells were evaluated for quantification of MCA.

RESULTS

Unlike nonmalignant pleural effusions, malignant pleural effusions were characterized by the presence of increased levels of MCA, and in lung adenocarcinoma (a cancer with high inflammatory cell infiltration), pleural levels of MCA were significantly greater than in small cell lung carcinoma (a cancer with low inflammatory cell reaction). An MCA concentration gradient between pleural fluid and plasma was present in malignant effusions because pleural MCA levels in all cancer types were significantly greater than MCA levels in the plasma of the same patients.

CONCLUSIONS

Thus, an increased local level of MCA is a feature of cancers with high inflammatory cell infiltration, and the presence of an in vivo concentration gradient of MCA suggests the direct role of this biologic activity in recruiting blood monocytes to the cancer site.

Mechanism for the recruitment of macrophages to cancer site. In vivo concentration gradient of monocyte chemotactic activity

BACKGROUND

Tumor stroma is characterized by the development of new blood vessels, an inflammatory cell infiltration, and a fibrotic reaction. The inflammatory component of tumor stroma plays an important role in the modulation of tumor expansion. In this respect, macrophages constitute a major part of the inflammatory cell infiltration and can exert cytotoxic activity against tumor cells. The accumulation of macrophages in the vicinity of the tumor suggests their recruitment from circulating blood monocytes through the local release of chemotactic factors for monocytes.

METHODS

To detect the existence of a concentration gradient of monocyte chemotactic activity (MCA) between the tumor vicinity and blood vessels, malignant pleural effusions defined by the local presence of cancer cells were evaluated for quantification of MCA.

RESULTS

Unlike nonmalignant pleural effusions, malignant pleural effusions were characterized by the presence of increased levels of MCA, and in lung adenocarcinoma (a cancer with high inflammatory cell infiltration), pleural levels of MCA were significantly greater than in small cell lung carcinoma (a cancer with low inflammatory cell reaction). An MCA concentration gradient between pleural fluid and plasma was present in malignant effusions because pleural MCA levels in all cancer types were significantly greater than MCA levels in the plasma of the same patients.

CONCLUSIONS

Thus, an increased local level of MCA is a feature of cancers with high inflammatory cell infiltration, and the presence of an in vivo concentration gradient of MCA suggests the direct role of this biologic activity in recruiting blood monocytes to the cancer site.

The estimation of whole blood viscosity by a porous bed method

A significant impediment in determining the relative contribution of whole blood viscosity to the pathogenesis of cardiovascular and cerebrovascular disease has been the lack of an uncomplicated method to measure whole blood viscosity. To address this problem, a simplified porous bed viscometer has been developed to measure whole blood viscosity. Whole blood is passed through a porous bed of branching channels with a mean pore diameter of 69.6 +/- 20.2 microns and an estimated mean shear rate of 19.6 seconds-1. The effects of sample collection, sample storage, and temperature are described. The mean whole blood viscosity of 242 healthy persons was 22.7 +/- 5.3 seconds, which, when corrected to centipoise using Darcy's equation, corresponds to an apparent viscosity of 5.7 +/- 1.3 cp. There was a significant difference in the whole blood viscosity of normal men and women related to their different packed cell volumes. Platelets and granulocytes influenced whole blood viscosity in proportion to their contribution to the total packed cell volume. Fibrinogen levels did not significantly influence measured whole blood viscosity, which is consistent with the disaggregating conditions and the mean shear rate of the instrument. The porous bed viscometer is a convenient means to measure whole blood viscosity and it should be useful as a screening test for clinical and epidemiologic studies.

Liquid preservation of polymorphonuclear leukocytes: effect of various additives on chemotaxis preservation

Adequate storage of polymorphonuclear leukocytes would allow an easier in vitro study of their structure and their functions, an easier study of polymorphonuclear leukocyte diseases (e.g. chronic granulomatous disease) and an easier use of polymorphonuclear leukocytes as a clinical tool (e.g. for localizing infections). Unfortunately, polymorphonuclear leukocytes are nearly impossible to preserve, even in short-term storage. This study proposes a model for the study of polymorphonuclear leukocyte storage in a synthetic medium: Plasmion. For storage over a period of 24 h, we found that supplementation with each of the following additives: bicarbonate buffer, glucose, adenosine triphosphate (ATP), ascorbic acid, nicotinamide adenine dinucleotide (NADH), nicotinamide adenine dinucleotide phosphate (NADPH), alpha-tocopherol acetate, amikacin and ampicillin, significantly improves (p less than 0.05) one or several functions of the polymorphonuclear leukocytes. When samples were stored for 48 h, we found that the addition of bicarbonate buffer after 24 h significantly improves the maintenance of several functions of polymorphonuclear leukocytes, in particular chemotaxis. Preservation for 96 h was achieved by making additions of supplements on each day of storage, with a chemotaxis maintenance of 83% at 24 h, 59% at 48 h, 46% at 24 h and 20% at 96 h. In conclusion, by using the Plasmion medium, and adding the above-mentioned compounds on each day of storage, chemotaxis can be satisfactorily maintained over 4 days.

Effect of plasma exchange on flumequine pharmacokinetics: comparison with control kinetics

The effect of plasma exchange (PE) on the pharmacokinetics of flumequine (Apurone) was studied in eight patients receiving a single oral dose of 800 mg. The maximum concentration (38 micrograms/ml) and time to maximum concentration (2.6 h) values were not significantly altered by PE beginning 3 h after administration of flumequine. There was no change in the terminal elimination half-lives (6.6 h), in the steady-state volume of distribution (29 L), or in the apparent plasma clearance (2.5 L/h). By contrast, PE decreased the mean residence time by 30% (14.3 +/- 4.1 h without PE; 9.88 +/- 1.36 h with PE; p less than 0.05). The amount of flumequine extracted by PE (72 mg) was proportional to the plasma concentration at the beginning of the exchange. The elimination half-life during PE (3.15 +/- 1.23 h) decreased by 40%. Renal clearance (0.3 L/h) was not affected. PE only partially modifies the pharmacokinetics of flumequine administered in a single oral dose before PE.

Study of parameters involved in specific immunoadsorption of apolipoprotein B

A therapeutic immunoadsorption system on immobilized and anti-apolipoprotein B as a plasma cholesterol lowering procedure was optimized. Several antibodies were compared and highest adsorption capacity was obtained with goat polyclonal antibodies. Optimum quantities of antibodies to be immobilized on the gel and quantities of apo-B to be applied to columns were determined. The amount of antibodies released from immunoadsorbents can be minimized by treatment with a 0.005% glutaraldehyde solution with an acceptable reduction rate of adsorption capacity. Each phase, adsorption and desorption respectively, were well-defined and synchronized so two columns could be used in parallel in an automated procedure. In these conditions, the immunoadsorption system can efficiently, specifically and safely remove cholesterol and has to be subjected to clinical trials.