Biomedical subjects

P Fondu

Publications and source records attributed to P Fondu.

At least 37 records · Page 2Linked to original sources

PubMed1996

Defective polymorphonuclear leukocyte functions in children receiving chemotherapy for cancer are partially restored by recombinant human granulocyte colony-stimulating factor in vitro.

Granulocyte colony-stimulating factor (G-CSF) has important direct and priming effects on different functions of normal mature polymorphonuclear leukocytes (PMNL). Previous study has shown an alteration in respiratory burst and bactericidal activities of PMNL harvested from children with cancer treated with chemotherapy. The present study evaluates the possibility that recombinant human (rh) G-CSF could correct these defective functions in vitro. Free radical formation in defective PMNL was enhanced by rhG-CSF to a level similar to that found in normal PMNL primed by rhG-CSF. The defective bactericidal activity against Escherichia coli and Staphylococcus aureus was also corrected. This bactericidal activity was not different from that observed in normal PMNL primed by rhG-CSF. In conclusion, correction of the altered free radical-formation pathway by rhG-CSF in these cells contributed to the restoration of normal bactericidal activity against both gram-positive and gram-negative microorganisms.

Adolescent↗

PubMed1996

Erythroblastopenia associated with methylmalonic aciduria. Case report and in vitro studies.

Various cytopenias, including neutropenia, thrombocytopenia and pancytopenia, have been reported in association with inborn errors of branched amino acid metabolism. We report here on a case of anemia associated with erythroblastopenia-that is less frequent in this context-in a neonate with methylmalonic aciduria. We used a semisolid erythroid culture system to investigate the effect on in vitro erythropoiesis of organic acids found in excess in this patient: methylmalonic (MMA) and propionic (PA) acids. First, the addition of 10% serum of the patient to a normal bone marrow progenitor culture suppressed the erythrocyte colony-forming unit growth in comparison to a pool of normal serum, while the addition of a 1:1 mixture of normal and patient serum resulted in an intermediate inhibition. MMA, when added to culture medium, resulted in a moderate inhibition of erythropoiesis only at a higher concentration than observed in our patient or reported in other cases. Conversely, PA showed an inhibitory effect at a concentration commonly observed in methylmalonic aciduria. The same effect was observed when the cells were in the presence of PA only for 72 h and then secondly plated in semisolid culture. Neither MMA nor PA showed any effect on the cell number and viability after a 3-, 4- or 7-day incubation except at the highest concentration tested.

Amino Acid Metabolism, Inborn Errors↗

PubMed1996

Granulocyte functions in children with cancer are differentially sensitive to the toxic effect of chemotherapy.

To analyze the toxicity associated to chemotherapy upon granulocytes, different functional assays were performed, within days of drug exposure and at time of bone marrow recovery, on polymorphonuclear neutrophils (PMN) from children with cancer. There were no significant postchemotherapy changes in the expression of the different receptors studied nor in the phagocytosis of Staphylococcus aureus 42D. By contrast, a significant decrease was observed in H2O2 production in PMN recently exposed to chemotherapy with both cytofluorometric and chemiluminescence assays. There was also a decrease in the production of O2- and in chemotaxis; finally, the intracellular killing of S. aureus 42D and Escherichia coli was reduced. In patients having recovered from drug-induced bone marrow aplasia, PMN functions were found to be normal except for bactericidal activity which was still defective. The observations indicate that, in patients exposed to chemotherapy, some PMN functions are transiently altered, whereas microorganism cell killing is continuously impaired.

Adolescent↗

PubMed1995

Heparin-associated thrombocytopenia: an update.

The use of heparin may be complicated by two types of thrombocytopenia (HAT): type I occurs early, is transient, and has no clinical relevance, while type II may lead to very severe manifestations (arterial or venous thromboses and more rarely bleedings), that are still underestimated by some clinicians. HAT-type II most frequently develops after use of therapeutic doses of unfractionated heparin (UH) but has also been described less frequently after use of very low doses of UH, of low molecular weight heparins (LMWH), and even of polysulfated glycosaminoglycosans devoid of anticoagulant action. The estimation of the incidence of HAT-type II and of related thromboses is a very difficult matter. Recent observations suggest that thromboses (notably venous) may be more frequent than previously estimated. HAT-type II pathophysiology includes the formation of immune complexes at the surface of platelets; the antigen has been shown to be most often platelet factor 4 bound to heparin while the antibody is recognized by platelet Fc gamma RII receptors. Thromboses result most probably from activation of both platelets (leading to the formation of microparticles) and endothelial cells. Several biological tests are presently available for diagnosing HAT-type II but none of them has been shown to be ideal. The prevention of HAT-type II requires history taking preference of LMWH to UH, early start of oral anticoagulation, and platelet monitoring from the fifth day of heparin therapy. The therapy of HAT-type II implies immediate discontinuation of heparin and avoidance of platelet transfusions, unless severe bleeding occurs. If further antithrombotic treatment is deemed necessary (probably in all cases), several options are possible but presently, the most recommended ones are Org 10172 or Ancrod; embolectomy or thrombolysis may also be required if a new thrombotic event has developed. A very difficult dilemma concerns patients previously sensitized to heparin and who present a clinical situation that theoretically mandates re-exposure to UH, such as by-pass surgery; prostacyclin analogues may be successfully used in such cases. Recent developments in the therapy of HAT-type II include recombinant hirudin or synthetic analogs, or use of some intravenous immunoglobulin preparations. Possible candidates are the heparin synthetic pentasaccharide and recombinant tissue factor pathway inhibitor.

Ancrod↗

PubMed1995

Transplanted sickle-cell disease patients with autologous bone marrow recovery after graft failure develop increased levels of fetal haemoglobin which corrects disease severity.

Bone marrow transplantation (BMT) is the only curative therapy for sickle-cell disease (SCD), but is not devoid of failure risk. Nine patients with severe SCD were grafted in our institution between 1988 and 1993. Six patients successfully engrafted, but three failed to engraft and had delayed autologous recovery. All patients had, prior to BMT, low levels of fetal haemoglobin (HbF < or = 3.5%). No change in HbF occurred in successfully grafted patients. In the three patients with graft failure HbF increased and remained persistently present at a high level (> or = 22%) 14 months, 16 months and 39 months post BMT, although two of the three patients were homozygous for either the Benin or the Central African Republic haplotype, a characteristic associated with low HbF level. Of interest, these three previously severely affected patients remain free of vaso-occlusive events. The mechanism responsible for the expression of high levels of HbF in our three patients with graft failure is not understood, but it protects them from the recurrence of severe vaso-occlusive crises.

Anemia, Sickle Cell↗

PubMed1995

Diagnosis of subtype 2B von Willebrand disease in a patient with 2A phenotype of plasma von Willebrand factor.

Type 2A of von Willebrand disease refers to qualitative variants with decreased platelet dependent function that is associated with the absence of high molecular weight forms of von Willebrand factor (vWF) multimers. Type 2B refers to qualitative variants with increased affinity for platelet glycoprotein Ib. In this report we describe the study of a patient who has been previously diagnosed as having subtype 2A von Willebrand disease (vWD), because she had no heightened ristocetin-induced platelet aggregation, no large and intermediate molecular weight von Willebrand factor (vWF) multimers in plasma, and no increase in plasma vWF capacity to bind to normal platelets in the presence of low ristocetin concentrations. The DNA sequencing of the 3' part of the exon 28 of the vWF gene where most of the subtype 2A mutations have already been identified, did not detect any nucleotide change. At variance, a G to A transition changing the encoded amino acid residue from Val 553 to Met in mature vWF, was found in the 5' part of this exon. This mutation which has already been found in several unrelated families with 2B vWD and the increased binding of the patient platelet vWF on normal platelets in the presence of low ristocetin concentrations provide evidence for subtype 2B vWD. This study thus illustrates the importance of the molecular characterization of patients in the correct diagnosis and classification of type 2 vWD.

Base Sequence↗

PubMed1995

Natural killer (NK) cells inhibit human umbilical cord blood erythropoiesis.

To examine the role of NK cells on in vitro human umbilical cord (HUC) blood erythropoietic progenitor growth, 25 normal HUC blood samples were depleted of CD56+ cells by using immunomagnetic beads coated with CD56 monoclonal antibodies (mAb). When stimulated by erythropoietin (Epo) to form colonies in plasma clot medium, the CD(56+)-depleted preparations demonstrated a two-fold increase in the number of early erythropoietic progenitors (BFU-E) over nondepleted preparations. This stimulatory effect of CD56+ depletion on BFU-E growth was not due to artifactual stimulations of other accessory cells by the mAb or the dynabeads used in the depletion procedure, since separate addition of these materials to culture did not exert any stimulatory effect on BFU-E growth. Direct co-culture of purified NK and autologous cord blood mononuclear cells (MNC) in plasma clot medium resulted in a dose-dependent decrease in BFU-E population. In addition, when NK and MNC were cocultured separately in double-layer cultures, the expansion of BFU-E was significantly decreased. Because direct cell-to-cell contact is prohibited in double-layer cultures, the observed inhibition of BFU-E proliferation could be mediated at least in part through soluble factors. To test this hypothesis, NK cell supernatant fluid obtained 24 hours after NK cell incubation was added to plasma clot culture medium. A significant decrease in BFU-E number was again observed. In conclusion, our results indicate that HUC blood BFU-E proliferation is inhibited by NK cells, and that the mechanism of this inhibition is mediated, at least in part, by one or more humoral factors.

Antigens, CD↗

PubMed1995

Pharmacokinetics and tolerability of factor XIII concentrates prepared from human placenta or plasma: a crossover randomised study.

The pharmacokinetics and tolerability of factor XIII (FXIII) from plasma were compared with those of FXIII from placenta in a randomised, double-blind, crossover study involving 13 patients with congenital FXIII deficiency. Both FXIII activity and FXIII antigen were monitored. No difference was seen in the mean half-lives of the two preparations (9.3 days and 9.1 days for plasma and placenta FXIII activity, respectively). Response was similar for both preparations, but was slightly greater for FXIII from plasma (1.6 ormula: see text] vs 1.5 [formula: see text]). Similar results were found for recovery (65% vs 60%). The area under the data completed by extrapolation was significantly higher for FXIII from plasma. No differences between preparations in terms of efficacy or tolerability were observed. It can be concluded that treatment with FXIII concentrate from plasma is as efficient as with FXIII concentrate from placenta in terms of recovery and half-life. Both preparations were equivalent in terms of safety during the observation period. With the administration of monthly injections of approximately 30 U/kg serious bleeding events were prevented and no other serious adverse events occurred.

Adolescent↗

PubMed1995

[Study of hemoglobinopathies found in Belgium].

Our purpose is to illustrate our contributions to the study of the haemoglobinopathies observed in Belgium. We described a new deletion leading to major thalassaemia and have established that the erythropoietin production is adequate in this disease. We were particularly interested in some manifestations of iron overload (polyendocrinopathy, roles of the decreased phagocytosis and of the desferrioxamine therapy in the predisposition to infections, protective role of desferrioxamine in the protection against the progression of HIV-1 infection). The prevention of thalassaemia major has deserved our particular attention. As concerns sickle cell anemia, we have underlined some particular aspects of the clinical expression of the disease. The use of new therapeutic approaches (bone marrow transplantation, hydroxyurea) has also been outlined.

Anemia, Sickle Cell↗

PubMed1994

Lithium inhibits calcitriol-stimulated formation of multinucleated cells in human long-term marrow cultures.

We observed that lithium (3 mM) blocked the 1,25-dihydroxyvitamin D [1,25-(OH)2D3]-stimulated bone resorption in fetal rat long bones in culture. Because this inhibitory effect was not seen when bone resorption was stimulated by parathyroid hormone or interleukin-1, we reasoned that Li specifically inhibited events involved in the 1,25-(OH)D3-stimulated bone resorption. The increased bone resorption induced by vitamin D in culture is associated with differentiation and/or fusion of osteoclast progenitors. In the present work, we studied the effect of Li on the basal and 1,25-(OH)2D3-stimulated generation of multinucleated osteoclast-like cells (MNC) and MNC containing tartrate-resistant acid phosphatase (TRAP+) in long-term human bone marrow cultures. Total MNC and TRAP+ cells were counted after 3 weeks of culture. In the absence of both lithium and 1,25-(OH)2D3, total MNC and TRAP+ cell numbers were 146 +/- 22 and 110 +/- 18 per well, respectively (mean +/- SEM); in the presence of Li, corresponding figures were 79 +/- 17 and 59 +/- 14. When the generation of MNC and TRAP+ cells was stimulated with 1,25-(OH)2D3, (10(-8) M), total MNC and TRAP+ cells were 521 +/- 66 and 473 +/- 63, respectively, in the absence of Li and 251 +/- 44 and 155 +/- 27 in the presence of Li (p < 0.05). The inhibitory effect of Li was dose dependent and was not observed when the cultures were exposed to parathyroid hormone instead of 1,25-(OH)2D3.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Marrow↗

PubMed1994

Dose of desferrioxamine and evolution of HIV-1 infection in thalassaemic patients.

To study the relationship between the dose of desferrioxamine (DFX) and the progression of the HIV-1 disease in thalassaemia major patients (TMP), 64 seropositive TMP patients were studied. Cumulative incidence of CDC stage IV was calculated using a non-parametric life-table method. The association with the mean daily dose of DFX was tested with a Cox proportional hazards model which was also used to adjust for confounding variables. The median of the mean daily dose of DFX over the seropositive period was 40 mg/kg (range 0-65 mg/kg). Age at seroconversion (P < 0.02) and splenectomy (P < 0.03) were found to be associated with the mean daily dose of DFX. 6.5 years after seroconversion, 11% of those who had been prescribed more than 40 mg/kg of DFX daily had entered stage IV versus 35% of those who had been prescribed a lower dose (P < 0.01). When the dose was taken as a continuous variable it was found that the rate of progression was significantly smaller in TMP receiving a higher dose (P < 0.002), even after adjusting for age and splenectomy (P < 0.02). Although it should be noted that these results were obtained in an observational study, possibly biased by a non-random allocation of the DFX dose, we believe that they are striking enough to support the claim that the role of DFX in the progression of HIV disease should be further evaluated.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Effects of zinc supplementation on the phagocytic functions of polymorphonuclears in patients with inflammatory rheumatic diseases.

The phagocytosis of blood polymorphonuclear cells (PMNs) was measured by cytofluorometry in 22 patients with inflammatory rheumatic diseases before and after a 60-day treatment with 45 mg zinc daily or a placebo, and the values were compared with those obtained in a group of healthy subjects. Plasma zinc was lower than controls before supplementation and phagocytosis assessed by the percentage of PMNs exhibiting phagocytic activity was significantly impaired. Zinc supplementation increased the percentage of phagocytic PMNs and the mean phagocytic activity, particularly in subjects with initial low phagocytosis. The impairment of PMN phagocytosis could therefore be corrected by zinc supplementation, but the clinical consequence of this stimulant effect remains unknown.

Administration, Oral↗

PubMed1993

Bone marrow transplantation corrects the splenic reticuloendothelial dysfunction in sickle cell anemia.

In sickle cell anemia (SCA), the loss of reticuloendothelial function is the result of vasoocclusive events occurring in the spleen. Such asplenia occurs early in the course of the disease and is considered to be permanent in late childhood. In this report, three patients 10, 11, and 14 years of age suffering from severe SCA and found to be asplenic were treated by bone marrow transplantation (BMT). Before transplantation, all three patients had loss of reticuloendothelial splenic function, as assessed by the presence of abundant Howell-Jolly bodies on blood smears and absence of technetium 99m (99mTc) splenic uptake. After BMT, Howell-Jolly bodies disappeared from blood smear, whereas 99mTc isotopic scan found normal isotope uptake. Our data indicate that BMT can correct "permanent asplenia" in SCA patients. However, it remains to be determined if such treatment can also correct other SCA-related organ dysfunctions.

Adolescent↗

PubMed1993

Applications of the monoclonal antibody PC10 assessment of proliferative grade in cell smears.

In view of the increasing need to assess the proliferative activity of hematologic malignancies, slide-based methods to quantify the proliferating cell nuclear antigen (PCNA) were developed and evaluated. Two techniques to evaluate this antigen were adapted to the infiltration level of the disease. The first one is particularly appropriate to massive invasion and is based on the alkaline phosphatase-antialkaline phosphatase complex (APAAP)method. The second one is reversed for reduced infiltration and uses a double immunofluorescence labeling. One is specific for the target cell to be identified and the other one is specific for the PCNA. These techniques permit an easy and accurate routine evaluation of cell cycle marker expression in hematologic malignancies.

Antibodies, Monoclonal↗

PubMed1993

Neutrophils from patients with secondary haemosiderosis contain excessive amounts of autotoxic iron.

Secondary haemosiderosis may be accompanied by a decrease in the phagocytic function of neutrophils (PMNs). This dysfunction has been attributed to an exaggerated generation of oxidants induced by intracellular iron. However, an accumulation of iron has so far not been reliably demonstrated in neutrophils harvested from iron-overloaded patients. Six polytransfused haemodialysed patients, with a serum ferritin level higher than 1000 micrograms/l, and 10 healthy controls were investigated. The iron status of PMNs was evaluated by iron determination using atomic absorption spectrometry and by ferritin measurement using radioimmunoassay. The phagocytic performance was measured by cytofluorometry. The results confirm that PMNs from the haemosiderosis patients have a decreased phagocytosis. Moreover, they demonstrate for the first time that these PMNs have an increased cellular iron and ferritin content. Both latter concentrations were 4 to 5 times more elevated in secondary haemosiderosis than in healthy controls. This iron accumulation may be toxic for the PMNs and may, at least partially, explain the three-fold higher risk of bacteraemia which has been reported in those patients.

Aged↗

PubMed1993

Accurate flow cytometric measurement of bacteria concentrations.

Accurate measurements of bacteria concentrations are required in numerous studies; they raise methodological problems that complicate, for instance, the investigations of polymorphonuclear neutrophil functions. We propose a new flow cytometric method of determining bacteria concentrations by comparison with a standardized fluorescent latex bead solution. Relative counts of beads and bacteria are established in a system using both fluorescence and light scatter for the two types of particles. On the one hand, the latex bead size (0.98 microns in diameter) permits counting on traditional hematological counters and, on the other, a flow cytometric detection with the same conditions for bacteria. The reproducibility of the study of bacteria concentration measurements gave a coefficient of variation of < 5%.

Bacteria↗

PubMed1993

Cardiac surgery with extracorporeal circulation in severe factor VII deficiency.

We describe here successful open heart surgery with extracorporeal circulation and haemodilution in a child with severe congenital factor VII deficiency. Substitution therapy was realized with factor VII concentrate (SD proconvertin concentrate, Bio-Transfusion). This is the first report case of successful cardiac surgery in severe congenital factor VII deficiency.

Child, Preschool↗

PubMed1992

Responsiveness to recombinant erythropoietin therapy in end-stage renal disease. An analysis of the predictive value of several biological measurements, including circulating erythroid progenitors.

In end-stage renal disease (ESRD), the human recombinant erythropoietin doses required to keep haemoglobin in the target range may vary considerably between patients. Previous studies have failed to find any predictive factor of the response. We thus performed the present investigation in 30 ESRD patients to discover if the haematological response to human recombinant erythropoietin (rHuEpo) was related to the results of circulating erythroid progenitor cultures. Peripheral erythroid burst forming units (BFU-E) were cultured in a plasma clot system in the absence or in the presence of autologous serum just before starting rHuEpo therapy. The results showed a higher BFU-E number in ESRD patients than in controls and a stimulatory effect of autologous serum in both patients and controls. Comparison between culture results and haematological response yielded positive correlation between the BFU-E number and the haemoglobin increase during the first month of treatment, and negative correlation between the increase of BFU-E numbers during the first week of therapy and the rHuEpo doses required for a long-term response. We thus conclude that in ESRD patients the individual response to rHuEpo is linked to the numbers of circulating BFU-E.

Adult↗