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Biomedical subjects

F Schooneman

Publications and source records attributed to F Schooneman.

At least 37 records · Page 2Linked to original sources
PubMed1996

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.

Adult↗
PubMed1996

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.

Blood Preservation↗
PubMed1995

The number of circulating CD34 positive cells is the best preleukapheresis parameter for predicting the quality of peripheral blood progenitor cell harvest.

Correlations between different peripheral blood parameters and harvesting yields of stem cells were analysed in 230 leukaphereses performed on 61 patients. According to multivariate analysis, the number of circulating CD34 positive cells was found to provide the best preleukapheresis parameter for predicting the quality of peripheral blood progenitor cell harvest. A high correlation coefficient and small 95% confidence and prediction intervals would indicate the assay of CD34 positive cells in peripheral blood to be a unique tool essential for monitoring the collection of circulating haematopoietic progenitors.

Adolescent↗
PubMed1994

[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.

Blood Platelets↗
PubMed1994

[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.

Anemia↗
PubMed1994

[Study of the platelet concentrate obtained with the MCS cell separator of the Society of Haemonetics].

The purpose of this work is to propose several platelets MCS programs which could be included in Haemapheresis Units. In the near future, one of our target is to decrease the transfusion risk. To reach this goal, it is very important to decrease the production of standard platelet concentrates from blood units by replacing them with platelet concentrates. For this work, we used MCS monitor from Haemonetics, equipped with two pumps. We have tested the platelet procedures by the mean of three programs (2.61, 3.61, 4.11 whole blood processed). The results showed good platelet yield (3.55, 4.82 and 5.37 1.10(11) for each program) with good quality of platelets up to 3 days storage (aggregation, beta-thromboglobulin release). The MCS machine could complete platelet apheresis systems and might in the future replace the classical standard platelet concentrates.

Blood Donors↗
PubMed1994

[Erythrocyte aggregation in patients treated by plasma exchange or plasma administration].

The kinetic (aggregation times) and rheological (dissociation threshold) parameters or erythrocyte aggregation were determined before and immediately after each plasma epuration, using a device based on the analysis of the back scattered light by a blood suspension. We used two techniques of plasma épuration: a) classical plasma exchange: 8 multiple myelomas, 6 Waldenström diseases, with 42 procedures tested; b) plasma treatment/cascade filtration: one Waldenström disease with 9 procedures tested and 37 procedures in one patient suffering from hypercholesterolemia. We have completed this study by checking the rheological parameters in 46 procedures applied in 6 patients with hypercholesterolemia. In these patients, we have used the Kaneka technique (dextran sulfate). The parameters studied were: primary (Ta) and final (Tf) aggregation times, total (gamma D) and partial (gamma S) dissociation parameters. In all cases, the results showed an important decrease of Ta and Tf (with good improvement) and an increase of dissociation parameters showing the efficacy of such therapies. Erythrocyte aggregation constitutes a good panel of parameters to appreciate abnormalities before and after plasma epuration.

Erythrocyte Aggregation↗
PubMed1993

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.

Blood Donors↗
PubMed1992

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.

Adenocarcinoma↗
PubMed1991

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.

Anticoagulants↗
PubMed1991

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.

Administration, Oral↗
PubMed1991

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.

Blood Preservation↗
PubMed1991

[Erythrocyte aggregation in patients with monoclonal gammopathies: effect of plasma exchange treatment].

Analyses of erythrocyte aggregation have been carried out in 15 patients with multiple myeloma or Waldenström's macroglobulinemia before and after plasma exchange. The volume of exchanged plasma was about 1.2-1.5 plasmatic mass. It was replaced by the same volume of a 4% solution of human albumin. Each treatment included at least 3 plasma exchanges at 48 hours intervals. The kinetic (aggregation times) and rheological (dissociation threshold) parameters of erythrocyte aggregation were determined before and immediately after each plasma exchange using a device based on the analysis of the backscattered light by a blood suspension. Before the first plasma exchange, erythrocyte aggregation measurements revealed a pronounced reduction in time aggregation and high values of dissociation thresholds indicating an hyperaggregation of red cells. The successive plasma exchanges produced very different changes in erythrocyte aggregation. For some patients, the aggregation parameters presented normal values from the first plasma exchange when similar changes were only noted after the second plasma exchange in other patients. Finally, in some cases, an hyperaggregation state was maintained after a series of three plasma exchanges. The influence of the nature and the concentration of monoclonal immunoglobulin as well as plasmatic fibrinogen are discussed.

Blood Viscosity↗