In vitro study of THP-doxorubicin retention in human leukemic cells using confocal laser microspectrofluorometry.

Microspectrofluorometry allows the analysis of fluorescent molecules such as anthracyclines in the nucleus of isolated living cells. Using this technique, we confirmed that the amount of doxorubicin or THP-doxorubicin incorporated into the nucleus was related to the resistant or sensitive character of K562 cells. It was then extended to the study of fresh leukemic cells and kinetic studies were performed allowing the calculation of the retention rate (RR) of anthracycline (THP-doxorubicin) into the cell nucleus. A reproducibility study confirmed the accuracy of the method. Blast cells collected in patients with acute myeloid (n = 22) or lymphoid (n = 8) leukemia, at diagnosis (n = 26), or in relapse (n = 4) have been studied. RR varied from 8 to 98% independently of the type of leukemia or the clinical status. RR did not correlate either with P-glycoprotein or with CD34 expression although this latter result should be confirmed on a higher number of subjects. Among 18 patients presenting with AML at diagnosis, 14 have been treated with intensive chemotherapy including anthracyclines; the only one who had resistant disease had the lowest RR value. In conclusion, the results obtained here show that microspectrofluorometry allows the performance of kinetic studies on fresh leukemic cells in order to quantify chemo-resistance phenomena related to drug transport.

Inhibition of fMLP-triggered respiratory burst of human monocytes by adenosine: involvement of A3 adenosine receptor.

Adenosine (Ado) is a potent anti-inflammatory agent acting on a variety of cell functions. However, its effects on human monocytes have been less well characterized. We investigated the effect of Ado and its receptor-specific analogs on NADPH oxidase activity with the use of luminol-enhanced chemiluminescence (CL). Adenosine inhibited fMLP-triggered NADPH oxidase activity with a maximal inhibition of 55+/-5%. IB-MECA, a selective A3 Ado receptor agonist reduced fMLP triggered NADPH oxidase activity more potently than the A2 receptor agonist CGS 2180 HCl (CGS) and the A1 Ado receptor agonist N-2-phenylethyl-adenosine (R-PIA). The inhibitory effect of Ado was reversed by neither the A1 Ado receptor antagonist 1,3-dipropyl-8(2-amino-4chlorophenyl)-xanthine (PACPX) nor the A2 Ado receptor antagonist 3,7-dimethyl-1-(2-propynyl)xanthine (DMPX). It was significantly reversed by the A1/A3 Ado receptor antagonist xanthine amine congener (XAC). Pretreatment of monocytes by cytochalasin B reversed the effect of Ado but not of dibutyryl cAMP (dBcAMP) on fMLP-CL response. KT 5720, a specific cAMP-dependent protein kinase inhibitor completely counteracted the inhibition of NADPH oxidase activity by dBcAMP but not by Ado. Using flow cytometry, we observed that Ado did not inhibit intracellular oxidative metabolism, whereas dBcAMP did. Furthermore, the inhibition of NADPH oxidase activity by Ado was not mediated by changes in cytosolic calcium. These results demonstrated that Ado inhibited NADPH oxidase activity via A3 Ado receptor independently of cAMP elevation or changes in calcium mobilization.

Multicenter evaluation of nine commercial kits for the quantitation of anticardiolipin antibodies. The Working Group on Methodologies in Haemostasis from the GEHT (Groupe d'Etudes sur l'Hémostase et la Thrombose).

The performances of nine commercial kits and an in-house method (HM) for the quantitation of anticardiolipin antibodies (ACA) have been evaluated in a multicenter study. Ninety control and patient samples and six standards from Louisville University were run with kits and with the HM. Marked differences in positivity rate between kits were observed, ranging from 31 to 60% for IgG and 6 to 50% for IgM. Concordance between kits occurred in 59 and 51% of samples for IgG and IgM respectively. Concordance coefficients (kappa) ranged from 0.13 to 0.92. Slopes of regression lines between the declared units of Louisville standards and the units measured from the calibrators of the kits showed great diversity and ranged from 0.159 to 0.931 for IgG and from 0.236 to 0.836 for IgM. The beta 2-glycoprotein I (beta 2-GPI) content of the dilution buffers and the wells supplied with the kits revealed noticeable differences. However samples containing anti-beta 2-GPI antibodies were classified similarly by all but one kit. In contrast the ability to measure samples devoid of anti-beta 2-GPI antibodies differed markedly between the kits. This study shows that differences in positivity rates between the commercial kits may contribute to the differences in ACA prevalence rate found in the literature. The choice of cut-off levels may partly explain the moderate concordance between the kits. In addition some samples behave very differently depending on the kits. In spite of the expression of results in PL units, standardization of ACA assays has not been achieved.

Use of the PFA-100 apparatus to assess platelet function in patients undergoing PTCA during and after infusion of c7E3 Fab in the presence of other antiplatelet agents.

The PFA-100 (Dade) is a new functional whole blood analyzer, the accuracy and reliability of which have been evaluated in von Willebrand disease and during acetyl salicylate acid therapy. This new test has the advantages of rapidity and simplicity. It may be useful to monitor new antiplatelet agents, such as GPIIb/IIIa receptor antagonists. The objective of this study was to assess the PFA-100 in comparison with aggregometry and with the percentage of blockaded receptors GPIIb/IIIa during and after c7E3 Fab infusion in fifteen patients undergoing PTCA. Our results showed a change of closure time values from normal to abnormal within a small margin of flow cytometric values (60-75% of blockaded receptors), and moreover a variable platelet response to long-term low dose aspirin treatment in agreement with aggregometry. No influence with heparin was observed. In conclusion, this study shows that PFA-100 may be helpful in the decision making for additional antiaggregant therapy before PTCA or in monitoring long-term GPIIb/IIIa receptor antagonist treatment.

Measurement of low molecular weight heparin ex vivo activities in clinical laboratories using various anti-Xa assays: interlaboratory variability and requirement for an agreed low molecular weight heparin standard.

The only sensitive and convenient assay to assess the biological activity of low molecular weight heparins (LMWHs) is based on the potentiation of activated factor Xa inhibition. Several procedures for measuring the socalled anti Xa activity have been proposed. In this collaborative study including eight laboratories, we have used four different assays (three amidolytic and one clotting based methods) for measuring the anti Xa activity of ex vivo samples obtained after injecting three different LMWHs. The dispersion of the results obtained by calibration against standard heparin could be reduced by using any of the three LMWHs for calibration. A coefficient of variation less than 0.20 between values obtained in different laboratories using a variety of methods seems acceptable. However it is necessary to refer to a common international standard for expressing the results in units and to define, for each of the three products, the therapeutic range.

Free and total platelet glycoprotein IIb/IIIa measurement in whole blood by quantitative flow cytometry during and after infusion of c7E3 Fab in patients undergoing PTCA.

A quantitative flow cytometry assay was used to evaluate the ex vivo kinetics of c7E3 Fab platelet effect in 16 patients undergoing PTCA treated with abciximab and compared with aggregometry assay. Immunolabeling of platelets was directly assessed on whole blood, using in parallel two monoclonal antibodies (Mabs) raised against GPIIIa, Mab1, the binding of which is inhibited by c7E3 Fab, and Mab2, the binding of which is not affected by c7E3 Fab. We found a severe and sustained inhibition of both GPIIb/IIIa receptors and platelet functions. The inter-individual variation in response to abciximab was low. A significant transient increase at H24 and H48 in the binding of Mab2 was found as an unexpected result, and confirmed in vitro. Results demonstrate that flow cytometry is a reliable method in agreement with aggregation. In addition, our results show that it is a standardized tool and a time-saving technique.

Intranuclear concentration measurements of doxorubicin in living leucocytes from patients treated for a lympho-proliferative disorder.

The accumulation of doxorubicin (DOX) in white blood cells of treated patients has been studied by quantitative microspectrofluorometry. From blood samples of treated patients, leucocyte subpopulations were separated by the gradient method. Emission fluorescence spectra from a microvolume of a single living cell nucleus were analysed in terms of spectral shape and fluorescence yield between free and DNA-bound doxorubicin. With this non-destructive analysis technique, intranuclear doxorubicin concentrations were determined within +/- 10%. Doxorubicin concentrations were measured in patients treated with bolus injection. After an accumulation of DOX in leucocytes during the first 30 min, intranuclear doxorubicin concentration did not vary significantly for 24 h, whereas its concentration in plasma decreased. Despite large differences between patients, monocytes accumulated significantly more doxorubicin than granulocytes or lymphocytes did.

Mechanisms of the platelet aggregation induced by activated neutrophils and inhibitory effect of specific PAF receptor antagonists.

The supernatant of polymorphonuclear neutrophils after their activation by opsonized zymosan induces the aggregation of washed platelets in human. It potentiates platelet aggregation induced by agonists in platelet rich plasma as well as in whole blood. This activation involves the phosphoinositide metabolism. Specific PAF receptor antagonists gingkolides (BN 50726, BN 52021, BN 54068, BN 54062, BN 50730, BN 50749, BN 50744) and benzodiazepine Web2086 antagonize this neutrophil-induced platelet aggregation. BN 50,730, BN 50,749 and Web 2086 can fully inhibit this aggregation at the final concentration of 10(-6) M. Preincubation of platelets with synthetic PAF also inhibits this activation through a desensitization of the receptor. These data suggest the major involvement in our model of PAF acether in the platelet-neutrophil interactions.

Variations of protein C in uremic hemodialysed patients.

Protein C has been measured by three different assays (antigenic, amidolytic and chronometric) in 27 end-stage renal insufficient patients before and after hemodialysis. Protein C levels have been compared with other coagulation inhibitors (antithrombin III, protein S) and fibrinolytic parameters. Baseline anticoagulant activity of protein C has been found impaired in eight cases whereas other inhibitors were normal. In four cases, both anticoagulant and antigenic levels were low. In one case, amidolytic method could also found a low activity. Hemodialysis leads to an increase of protein C activity and antigen level. Heparinemia after hemodialysis does not interfere with the chronometric measurement of protein C anticoagulant activity. Total protein level, hematocrit, protein S and antithrombin III are also elevated after hemodialysis. Baseline fibrinolytic parameters are normal and remain unchanged after hemodialysis. The clinical relevance of such modifications is discussed.

Factor V Leiden: detection in whole blood by ASA PCR using an additional mismatch in antepenultimate position.

Factor V Leiden mutation was initially detected in thrombophilic patients and relatives by PCR RFLP (Restriction Fragment Length Polymorphism) according to Bertina (1). This technique presents some drawbacks and the current trend is to simplify the diagnosis. We describe a technique of Allele Specific Amplification (ASA) which is optimized in terms of reliability: an additional mismatch in antepenultimate position enables to obtain the same specificity as PCR RFLP. Furthermore, coamplification of internal control warrants an optimal sensitivity. All the PCR have been simplified: the DNA extraction improvement allows to analyse the genotype with only a few microliters of whole blood whatever the anticoagulant and the procedure of preservation (freezing, dried blood spots, storage at +4 degrees C for several days). This technique saves time. Moreover, full automation of the ASA technique may be shortened thanks to the lack of extraction and the positive/negative reading of the PCR signal.

Plasma levels of tumor necrosis factor-alpha (TNF-alpha) are essentially dependent on visceral fat amount in type 2 diabetic patients.

TNF-alpha is considered as one of the potential determinants of insulin resistance. However several data suggest that TNF-alpha expression itself, could be modulated by the degree of adiposity and/or plasma insulin levels. To clarify the determinants of plasma TNF-alpha levels in type 2 diabetes mellitus, we studied the impact of intensive insulin treatment on plasma TNF-alpha levels in 16 type 2 diabetic subjects with failure to oral antidiabetic medication (HbA1c: 10.8 +/- 1.2 %). Furthermore, we analyzed the relationship between plasma TNF-alpha levels and total or regional body fat measurements using anthropometry, bienergetic absorptiometry and computed tomography in a cohort of 33 caucasian obese type 2 diabetic subjects (BMI: 32.2 +/- 4.4 kg/m(2) ). The plasma TNF-alpha level was neither affected by plasma glucose level variations nor intensive insulin treatment despite a 37 % decrease in daily insulin needs at the end of insulin therapy (total duration: 11.5 +/- 2.0 days). The plasma TNF-alpha level was similar in men and women and unrelated to age, fasting glycemia or HbA1c. A relationship was highlighted with BMI (r =0.39, p <0.02), but not with total fat mass. This relationship was only dependent on the intra-abdominal fat mass amount as assessed by the waist-to-hip circumference ratio (r =0.52, p <0.01) and the visceral adipose tissue area (r =0.56, p <0. 01). These results show that plasma TNF-alpha levels are essentially dependent on visceral fat amount, thus suggesting that TNF-alpha could be one of the factors mediating insulin resistance and cardiovascular risk in obese type 2 diabetic patients.

Microencapsulation IV: Cross-linked hemoglobin microcapsules.

Hemoglobin microcapsules were prepared through cross-linking of hemoglobin itself with various acyldichlorides. Variations in the reticulation conditions were preformed in order to ameliorate the oxygen dissociation curve, the mean diameter, and the possibility for the microcapsules to be lyophilized. With terephthaloylchloride, as the cross-linking agent, incorporation of inositol hexaphosphate and glucose, followed by stabilization through glutaraldehyde and using high stirring speed, allowed preparation of stable hemoglobin microcapsules, 5 micrometers in diameter, which suffered rapid lysis by proteases. They were able to ensure oxygen transfer: the dissociation curve was sigmoidal with a p50 = 13 mm Hg. They retained these properties after lyophilization followed by rehydration.

Multicenter study of an erythro-aggregometer: quality control and standardization.

There is a need for quality assurance procedures in hemorheology, especially for clinical and pharmacological studies, which require reliable and well-calibrated instruments to be interpretable and comparable. Preliminary investigations allowed preparation of standardized SM (normal NS and hyperaggregable HS), and checking of storage conditions (in accordance with the guidelines of the SSC of ISTH) of RBC in nutritive SAG mannitol for at least 2 or 3 weeks with subsequent washings and resuspension in SM. In our study, we compared erythro-aggregometers of the same brand in 6 laboratories, using the same red blood cells (RBC) and suspending media (SM) for each series of tests. EA was measured by laser backscattering with determination of aggregation time (AT), partial dissociation threshold (PDT) and aggregation index (AI). Prior to the study, devices were set up on the same day with the same standardized blood, and calibration data were then analyzed. Within-assay precision (WAP) was assessed on 3 days for the 2 types of SM (n = 18 x 2). Between-assay precision (BAP) was assessed on 6 occasions, once every month (n = 6 x 2 x 6). Accuracy was studied with 3 series of RBC resuspended in 10 SM of "unknown" aggregability. Good agreement was observed between 5/6 centers for the 3 parameters of EA. WEP was good: CV of AT ranging from 1.4 to 2.5% for the NS and from 1.4 to 2.4% for the HS. In each center, BAP was slightly lower than WEP (CV: 8-11.8% for the NS and 3.8-4.7% for the HS over the 6-month study), with no drift, except for one center. Precision was always better with the HS than with the NS which seemed a better tool to assess it. As to accuracy, non-significant differences were generally found between centers, with similar data to the reference values. This work also stressed the importance of the RBC parameter itself in rheological data. For the first time, a protocol for standardization of EA has been developed and evaluated, permitting the Quality Control of this technique.

[Fibrinogen: a risk factor]. / Le fibrinogène: facteur de risque.

More than 10 epidemiologic studies have established that a high fibrinogen level is a thrombotic risk factor. The role of fibrinogen in arterial occlusion is multiple : the atheroma plaque involvement in formation thrombus, erythrocyte aggregation, whole blood and plasma viscosity. Fibrinogen level is high during inflammation and increases with ageing and in tobacco addicts. In coronary disease, it is an independent risk factor of prognosis value. In arterial peripheral disease, it is a risk factor of postsurgical reocclusion. After a stroke, a high level of fibrinogen is a sign of severe disease. The dosage of fibrinogen is quite easy but requires a precise calibration. The determination of genetic polymorphism associated with high fibrinogen level is promising. Many circumstances can modify fibrinogen level and are targets for prophylaxis treatments. The influence of genetic factors is still discussed.

[Hemorheologic changes in preoperative hemodilution during total hip replacement. Randomized study comparing hydroxyethyl starch 200,000/0.62 (HES) and a dextran 60,000]. / Modifications hémorhéologiques au cours des hémodilutions préopératoires des prothèses totales de hanche. Etude randomisée comparant un hydroxyéthylamidon 200,000/0.62 (HEA) et un dextran 60,000.

Hemodilution can be used to save blood transfusion during total hip replacement. We have carried out a randomized study to compare the hemorheological effects of two plasma substitutes: a hydroxyethylstarch 200,000/0.62 versus a dextran 60,000. Twenty-two patients were hemodiluted with 20 mk/kg of either substitute, just after the spinal anesthesia. Whereas the hematocrit have fallen by 30% in the two groups, significant differences are observed about hemorheological parameters. The plasma viscosity express a greater increase at hour 4 in the dextran group. The whole blood viscosities are more increased in the dextran group at hour 4 and 24. The erythrocyte aggregation is decreased in the HES group at hour 4 and 24, but is increased in the dextran group. The fibrinogen is more increased in the dextran group at day 7. In spite of similar hemodilutions, the two substitutes express different hemorheological effects with a favourable role of HES on erythrocyte aggregation and blood viscosities. This can improve the microcirculation and decrease the activation of the endothelial cells, reducing the inflammatory reaction.

[Respiratory burst of neutrophils and cytokine profile in the non-insulin-dependent diabetic]. / Explosion respiratoire des polynucléaires neutrophiles et profil des cytokines chez le diabétique non insulinodépendant.

Many clinical and experimental data are in favour of a participation of leukocytes in vascular disease. Diabetes, a risk factor, is associated with a dysfunction of neutrophils. If chemotaxis and phagocytosis are deficient, it is not clearly established whether superoxide generation is conserved in these patients. We have measured this function in 35 noninsulin dependent diabetic patients, compared with a control population. We have assessed, in parallel, a profile of the cytokines involved in vascular phenomenons including TNF alpha, IL-1 beta et IL-6. Our results indicate that the generation of free radicals is normal in diabetics, with a significant elevation of TNF alpha. These results suggest a possible participation of this cytokine in the modulation of granulocyte reactivity.

[Study of blood sedimentation by photo-thermal radiometry with random excitation]. / Etude de la sédimentation sanguine par radiométrie photothermique sous excitation aléatoire.

The erythrocyte sedimentation rate is a complex phenomena involving a large number of parameters. The rate of sedimentation is highly dependent on the haematocrit, the internal viscosity of the red cells and the viscosity of the suspending medium and its composition. The experimental conditions also have a non-negligible effect (geometry and nature of the test tube, temperature, foreign substances in the medium...). In order to respond to the need for more precise and more rapid methods of analyzing the erythrocyte sedimentation rate, we developed new physical methods allowing a real time evaluation of the phenomena involved. Several of these new photothermal methods have already been applied for non-destructive evaluation of thin or layered material (such as composite material or glued structures) both in laboratory situations and in the industry. When a material is placed in a modulated laser beam, the incident rays absorbed heat the sample. The heat then diffuses throughout the material and the surface temperature of the sample increases locally with a periodicity. The surface thus emits a modulated flow of infrared radiation. The amplitude and phase shift of the photothermal signal generated is characteristically dependent of the optic and thermal properties of the material for a given modulation frequency. The early photothermal modelling based on a two-layer model and a physico-mathematical theory of red cell sedimentation proposed by S. Oka made it possible to simulate the phenomena as they occur over time. We hypothesize that the temperature gradients created within the sample are too small to create a convection current and that the all heat transfer occurs by conduction.(ABSTRACT TRUNCATED AT 250 WORDS)

[Modulators of leukocytic functions]. / Les modificateurs des fonctions leucocytaires.

Polymorphonuclear neutrophils (PMN) and monocytes play a role in vascular diseases. Animal experimental models, using deleukocytation or injection of anti-CD11b-anti-CD18 monoclonal antibodies (inhibition of leukocytic adhesion and of interaction with the endothelial cell) have confirmed this role in the ischemia-reperfusion syndrome and in myocardial infarction. In man, increased production of oxygen radicals, PMN release of elastase, increased monocyte formation of tissue factor (TF) and integrins have been noted in coronary artery disease, in chronic arteriopathy of the lower limbs and in association with vascular risk factors such as diabetes. Pharmacological alteration of leukocyte hyperactivity therefore seems to be justified. Pentoxifylline, used with good effect in arteriopathy of the lower limbs, affects numerous leukocytic functions: diminution in adherence and in PMN production of free radicals, diminution in the formation of TF and cytokines (TNF). Gingkolides reduce leukocytic interactions and platelet activation through an anti-PAF (Platelet Activation Factor) action. Aspirin may interfere with free radicals and inhibit TF formation. alpha-tocopherol blocks the activation, by free radicals, of the transcription factor NF k B. By altering the TNF and IL-1 cytokines, leukocytic activation can be controlled. Other cytokines (IL-4, IL-10) have an immunosuppressive action and reduce the formation of TF. The pharmacological targets are therefore multiple. Their use in vascular diseases is only at a very preliminary stage.

[Vascular disease and cellular activation: exploration of cell adhesion phenotype by quantitative flow cytometry]. / Pathologie vasculaire et activation cellulaire. Exploration du phénotype cellulaire adhérent par cytométrie en flux quantitative.

The pathogenesis of atheromatous and/or thrombotic vascular diseases involves rheological parameters, soluble mediators and cellular agents. The many studies that have tried to establish correlations between plasma factors, shear stress and the risk of ischemia have left some questions unanswered. Current exploration methods are now focusing on the determining role of cells. Activated cells express adhesion molecules on their membranes, which allow to communicate in a homo- or heterotypical manner. Quantifying adherence molecules on the surface of platelets, leukocytes and endothelial cells provides an assessment of the "adhesive phenotypical profile". Quantitative cytometry, using beads coated with a known amount of immunoglobulins as calibrators, is perfectly suited, through its multiple parameter analyses and the specificity provided by monoclonal antibodies, for the quantification of membrane antigens. Measuring the adhesive profile on the surface of cells that are implicated in vascular disease makes it possible to correlate that phenotype to the ischemic risk in such diversified pathologies or circumstances as intermittent angor, myocardial infarction, angioplasty, insulin-dependent diabetes or pre-eclampsia. In addition, that quantification permits monitoring the action of new therapeutical agents targeting adherence molecules.

[Platelet-leukocyte interactions in coronary heart disease: pathophysiology, clinical relevance, pharmacological modulation]. / Interactions leucoplaquettaires au cours de l'insuffisance coronarienne. Physiopathologie, pertinence clinique, modulation pharmacologique.

The interactions between leukocytes and endothelial cells have been studied extensively under conditions of ischemia and reperfusion. In contrast, attraction of leukocytes by platelets at the site of damage is poorly understood. This recruitment facilitates inflammation and atherogenesis. Studies performed ex vivo in coronary artery disease show that neutrophil-platelet adhesion increases in unstable angina, coronary angioplasty and coronary artery bypass surgery, in comparison with stable angina. Experimental works have shown the major role of platelet P-selectin in platelet-leukocyte interactions, and of fibrinogen, which is the ligand of both platelets and leukocytes (B2 integrins). Studied performed in anti-GPIIb/IIIa-treated patients demonstrate a modulation, as inhibition, of platelet-leukocyte interactions. This new drug inhibits platelet function and coagulation, and moreover inflammation.