PubMed Health⌕ Search

Biomedical subjects

A Marfaing-Koka

Publications and source records attributed to A Marfaing-Koka.

15 recordsLinked to original sources
PubMed2002

Plasminogen activation by blood monocytes and alveolar macrophages in primary pulmonary hypertension.

The pathophysiology of primary pulmonary hypertension (PPH) remains poorly understood. Vascular wall remodeling and endothelial dysfunction reflected by modifications in plasma fibrinolytic proteins and von Willebrand factor have been well documented in PPH. We hypothesize that endothelial mediators, produced in excess in PPH patients, may stimulate migrating mononuclear cells and thereby modulate alveolar macrophage function; in particular, the plasminogen activation system. Components of the fibrinolytic system were therefore studied in plasma, blood monocytes and alveolar macrophages obtained from bronchoalveolar lavage in 10 patients with PPH and in four controls. Compared with controls, PPH patients had elevated plasma levels of tissue-type plasminogen activator (15.6 +/- 9.9 versus 5.5 +/- 3 ng/ml) and plasminogen activator inhibitor-1 (27.8 +/- 23 versus 16.4 +/- 12 ng/ml). In contrast, binding and activation of plasminogen by single-chain urokinase-type plasminogen activator (scu-PA) at the surface of blood monocytes and alveolar macrophages were not different from those of control values. Dissociation constants (K(d)) for binding of scu-PA and plasminogen to alveolar macrophages were similar in both PPH (4.7 +/- 1.5 and 0.88 +/- 0.3 micromol/l, respectively) and control (6.7 +/- 0.1 and 1.02 +/- 0.12 micromol/l, respectively) groups. These results indicate that in PPH patients the fibrinolytic activity of alveolar macrophages is normal, whereas endothelial fibrinolytic proteins are abnormally elevated in plasma.

Adult↗
PubMed2001

[Regenerative nodular hyperplasia: variable clinical aspects].

BACKGROUND: Regenerative nodular hyperplasia can take on very misleading aspects making diagnosis difficult. CASE REPORTS: We report three cases of regenerative nodular hyperplasia (RNH). In the first patient rupture of esophageal varices was associated with myelofibrosis. In the second, extensive portal thrombus formation was associated with consumption coagulopathy and essential thrombocytemia. The third patient had systemic sclerodermia, hepatic macronodules, refractory exsudative ascitis and chronic hepatic encephalopathy following surgery for a porto-cava anastomosis. DISCUSSION: The diagnosis of RNH should be suspected in a variety of clinical situations with search for associated diseases in all cases. The prognosis is related to the consequences of portal hypertension and the severity of the associated diseases.

Adult↗
PubMed1998

The biological basis of immune heparin-induced thrombocytopenia.

Heparin induced thrombocytopenia (HIT) remains the most severe adverse effect of heparin therapy. Recently, new information has been uncovered regarding the pathogenesis of this disorder. This review summarizes the clinical state, pathogenesis and diagnosis of HIT. It was stimulated by the recent recognition of heparin-platelet factor 4 (H.PF4) complexes as the major target antigen for heparin-dependent antibodies involved in this pathology. The formation of complexes between PF4 and heparin or other glycosaminoglycans, leading in some circumstances to the generation of antigenic structures reactive with HIT antibodies, is analysed. We also discuss how antibodies develop in heparin-exposed patients and why these antibodies can become pathogenic only in some patients, while their presence remains asymptomatic in others. This review also focuses on the mechanisms that could be involved in the development of thrombocytopenia and thrombosis. This new understanding of HIT pathogenesis has permitted the introduction of new tools for retrospective or prospective diagnosis, and may provide new strategies for the avoidance or treatment of HIT and its complications.

Journal Article↗
PubMed1997

Absence of cross-reactivity of SR90107A/ORG31540 pentasaccharide with antibodies to heparin-PF4 complexes developed in heparin-induced thrombocytopenia.

New carbohydrate-based anticoagulants devoid of the side effects of unfractionated heparin are currently under development and show a major potential for patients with heparin-induced thrombocytopenia (HIT) who still require efficient antithrombotic therapy. As HIT is usually associated with antibodies to heparin-platelet factor 4 (H-PF4) complexes, cross-reactivity of the heparin pentasaccharide SR90107A/ORG31540 was tested in the presence of PF4 with the plasma from 49 patients with HIT. No cross-reactivity was observed whatever the pentasaccharide concentrations. Although more extensive studies are required for excluding its total absence of immunogenicity and pathogenicity, this pentasaccharide is a candidate for use in emergency situations in patients with HIT.

Autoantibodies↗
PubMed1996

Presence of autoantibodies to interleukin-8 or neutrophil-activating peptide-2 in patients with heparin-associated thrombocytopenia.

Eighty-seven patients with heparin-associated thrombocytopenia (HAT) showed either a positive heparin platelet aggregometry test result and/or the presence of antibodies to heparin-platelet factor 4 (H-PF4) complexes by enzyme-linked immunosorbent assay (ELISA). Fifteen of these patients lacked antibodies to H-PF4, and plasma from these patients was analyzed for the presence of antibodies to PF4-related chemokines, Neutrophil-activating peptide-2 (NAP-2) and interleukin-8 (IL-8). Of these 15 patients, 6 showed antibodies to IL-8 and 3 to the platelet basic protein (PBP)-derived protein, NAP-2. Antibodies to IL-8 and NAP-2 were not observed in control patients (n = 38), patients with HAT and H-PF4 autoantibodies (n = 72), patients with autoimmune diseases (n = 21), or patients with non-HAT thrombocytopenia (n = 30). Five of these nine patients with anti-IL-8 or anti-NAP-2 developed thrombosis during heparin treatment, which is not statistically different from the patients with H-PF4 antibodies. The existence of autoantibodies to IL-8 and NAP-2 in HAT patients highlights the significance of chemokines in the pathogenesis of HAT. The contribution of heparin in vitro was minimal in patients with anti-IL-8 and anti-NAP-2 antibodies, suggesting a biologic difference from the majority of patients with HAT and anti-PF4 antibodies. It may be that antibodies to IL-8 and NAP-2 have weaker affinity for heparin and that the ELISA system may not reflect in vivo heparin-chemokine complex formation. Alternatively, antichemokine autoantibodies may predate heparin exposure, and the role of heparin in initiating HAT may be to mobilize the chemokines and to target them to platelets, neutrophils, or endothelial cells. Subsequent chemokine-binding autoantibodies then lead to cell activation resulting in thrombocytopenia and thrombosis.

Adult↗
PubMed1996

In vivo role of IL-6 on the viral load and on immunological abnormalities of HIV-infected patients.

In vitro experiments have suggested that interleukin (IL)-6 may contribute to human immunodeficiency virus (HIV) burden and to immunological abnormalities in HIV-infected patients. We had the opportunity to directly address this question in vivo through the virological and immunological monitoring of HIV-infected patients treated with an anti-IL-6 monoclonal antibody (mAb) for a lymphoma (ANRS 018 trial). Sixteen courses of anti-IL-6 mAb administration, performed in 11 patients, were studied. All patients were at a late stage of HIV infection. The HIV load and the immunological status were determined at the initiation of each course and at its end, 21 days later. The mAb induced no significant change of HIV load, as evaluated by p24 antigenemia, plasma viremia, and quantification of circulating HIV RNA by reverse transcriptase-polymerase chain reaction and branched DNA techniques. The anti-IL-6 mAb also did not affect CD4+, CD8+, and CD19+ circulating cell counts, nor the serum concentrations of sIL-2R and of sCD8. In contrast, the mAb completely abrogated acute-phase reaction, as demonstrated by the normalization of C-reactive protein and fibrinogen circulating levels (p = 0.013 and p = 0.008, respectively). It increased serum albumin concentration. The latter effect was restricted to patients with a spontaneously low albuminemia (p = 0.01). It decreased B-lymphocyte hyperactivity, as reflected by decreased IgG and IgA serum levels (p = 0.008 and p < 0.001, respectively), and by a decreased production of IgG in vitro (p = 0.017). In contrast, the IgM hyperproduction was not affected by the mAb. Therefore, increased IL-6 production in HIV-infected patients at a late stage of the infection may not stimulate HIV replication in vivo, but it may represent a key mechanism contributing to the metabolic and immunological dysbalance of the disease.

Acute-Phase Proteins↗
PubMed1996

Contrasting effects of IL-4, IL-10 and corticosteroids on RANTES production by human monocytes.

RANTES is a chemokine produced in delayed-type hypersensitivity (DTH) and allergic reactions, in which it may contribute to the recruitment of immune cells. Macrophages participate in the cellular infiltration in both conditions and they represent a potent source of RANTES. To understand the regulation of RANTES production by human monocytes, we analyzed the effect of cytokines and of corticosteroids on this production. We showed that IFN-gamma and tumor necrosis factor (TNF)-alpha cooperated to induce RANTES production by monocytes. N-acetylcysteine inhibited this effect, indicating that reactive oxygen intermediates are required for RANTES production. Both IL-10 and corticosteroids antagonized the stimulating effect of IFN-gamma and TNF-alpha on RANTES production. In contrast, IL-4 had no effect on IFN-gamma-induced RANTES production and it potentiated the positive effect of TNF-alpha on this production. Thus, the deactivating properties of IL-10 and corticosteroids on macrophage functions include RANTES production, and this may contribute to the immunosuppressive effect of both compounds in DTH and allergic reactions. In contrast, IL-4 has an opposite effect on RANTES production and this property may contribute to cell recruitment in allergic reactions. Therefore, although IL-10 and IL-4 belong to the Th2 family of cytokines, they can display distinct functions in immune reactions.

Acetylcysteine↗
PubMed1995

Regulation of the production of the RANTES chemokine by endothelial cells. Synergistic induction by IFN-gamma plus TNF-alpha and inhibition by IL-4 and IL-13.

Production by endothelial cells of the regulated on activation normal T expressed and secreted chemokine (RANTES) has recently been evidenced during delayed-type hypersensitivity (DTH) reactions and may contribute to the local accumulation of macrophages and CD4+ memory T lymphocytes. To document the mechanism inducing RANTES production in this condition, we analyzed the effect of cytokines known to influence the formation of DTH granulomas. Little or no RANTES was produced after stimulation of HUVEC with IFN-gamma, IL-1 beta, or TNF-alpha. However, the combination TNF-alpha+IFN-gamma induced a strong RANTES production. In situ hybridization experiments with a RANTES probe showed that this synergy was also observed at the mRNA level and that the effect of the combination was mainly to increase the amount of RANTES mRNA per cell. The expression of the luciferase gene under the control of the RANTES gene regulatory elements was analyzed; TNF-alpha and the combination TNF-alpha+IFN-gamma activated the regulatory elements. Sequential treatment of HUVEC with TNF-alpha and IFN-gamma showed that IFN-gamma sensitized HUVEC to the stimulating effect of TNF-alpha. The production of RANTES induced by TNF-alpha+IFN-gamma was partly but significantly inhibited by the Th2-type cytokines IL-4 and IL-13. In contrast, IL-10 had no effect. These results indicate that the microenvironment of DTH granulomas, containing high levels of both TNF-alpha and IFN-gamma, may be responsible for RANTES production by perigranulomatous endothelial cells. Inhibition of this production by Th2-type cytokines may be a mechanism by which these cytokines interfere with the formation of DTH granulomas.

Chemokine CCL5↗
PubMed1994

Production of the RANTES chemokine in delayed-type hypersensitivity reactions: involvement of macrophages and endothelial cells.

To understand the selective accumulation of memory T helper lymphocytes and of macrophages in delayed-type hypersensitivity (DTH) granulomas, we studied the in situ production of RANTES, a chemokine initially characterized on the basis of its in vitro chemotactic properties for each of these cell populations. RANTES gene expression was studied by in situ hybridization in 15 human lymph nodes presenting typical DTH lesions related to either sarcoidosis or tuberculosis. A positive signal was detected in all cases. Labeling was specific for the DTH lesions, as very few if any positive cells were detected in the normal residual lymphoid tissue surrounding them or in reactive lymph nodes involved in a B lymphocyte response. RANTES gene expression was associated with the production of the protein, which was detected by immunochemistry in DTH lymph nodes. The morphological characteristics and distribution of positive cells in in situ hybridization and immunochemical experiments indicated that macrophages and endothelial cells, two cell populations not previously reported to produce RANTES, contributed to its production in DTH reactions. The ability of macrophages and endothelial cells to produce RANTES was confirmed by in vitro studies with alveolar macrophages and umbilical vein endothelial cells. In view of the chemotactic properties of RANTES for a limited range of cell populations, these results suggest that RANTES production in DTH granulomas may play a role in the selective accumulation of macrophages and memory T helper lymphocytes characterizing this type of cell-mediated immune reaction, and that macrophages and endothelial cells are involved in this production.

Cells, Cultured↗
PubMed1994

New direct assay of free protein S antigen using two distinct monoclonal antibodies specific for the free form.

Monoclonal antibodies (mAbs) specific for free protein S and devoid of reactivity with protein S-C4b-BP complexes, have been produced. A one-step sandwich-type enzyme-linked immunoassay (ELISA) has been developed with two mAbs reacting with distinct epitopes of free protein S. F(ab')2 fragments from mAb 15C4 were coated on microplates and mAb 34G2 conjugated with horseradish peroxidase (HRP) was added immediately before diluted plasma. The presence of calcium in the sample diluent prevented dissociation of complexes during the assay. This assay was specific as demonstrated by good recovery of purified protein S added to plasma and the lack of influence of C4B-BP-protein S complexes. Thus, addition of increasing amounts of purified C4B-BP to human citrated plasma induced a dose-dependent decrease of free protein S. The assay was sensitive, allowing measurement of 5-500 ng/ml of free protein S, with a detection threshold of 2 ng/ml. It was also reproducible with inter-assay and intra-assay variation coefficients of 2.5-5.1% and 3.1-5.0%, respectively. Thus, this new ELISA of free protein S antigen in plasma has the advantages of being fast, accurate and reproducible. It appears to be extremely useful for routine studies as no preliminary treatment of plasma is required.

Antibodies, Monoclonal↗
PubMed1994

Clinical applications of a direct assay of free protein S antigen using monoclonal antibodies. A study of 59 cases.

A new one-step ELISA using two monoclonal antibodies specific for distinct epitopes of the free form of protein S (ELISA-m) has been developed for the direct measurement of free protein S in untreated plasma. This assay has been compared with the classic method using polyclonal antibodies to protein S (ELISA-p). The latter method has the drawback of requiring PEG precipitation of plasma which is time-consuming, difficult to perform with accuracy and therefore poorly reproducible in most laboratories. Results of both ELISAs were compared with those of a functional assay. In 30 normal subjects, there was an excellent correlation between ELISA-m and ELISA-p (r = 0.95) as well as between ELISA-m and the functional assay (r = 0.96). In twelve patients with a congenital deficiency, the levels of free protein S antigen were similarly decreased with ELISA-m and ELISA-p and in good agreement with those of protein S activity. In 20 patients with miscellaneous inflammatory diseases, the levels of free proteins S were normal with good correlation between both ELISAs and PS activity, despite high levels of C4bBP-protein S complexes. As expected, in 15 dicoumarol-treated patients, there was a significant and parallel decrease of free protein S antigen with both ELISAs, with even lower levels of protein S activity. In 14 patients with liver cirrhosis, the mean values for free protein S antigen were normal using both assays, but with wide extreme values, whereas protein S activity was significantly lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1993

Decreased protein S activity in sickle cell disease.

In sickle cell disease (SCD), vaso-occlusion is a complex process involving cellular, vascular and humoral factors and possibly thrombotic events. We studied three physiological inhibitors of the coagulation system, antithrombin III (AT III), protein C (PC) and protein S (PS), in three groups of subjects: 27 homozygous patients observed either in crisis or in a steady state, 23 heterozygous patients and 30 healthy subjects. PS study included the measurement of total and free PS antigen, PS activity and C4bBP antigen. In heterozygous subjects the results were similar to those of controls, but in homozygous subjects abnormalities of PS and to a lesser extent PC were observed. Values of PC were extremely variable with 10 cases lower than the normal range (2 SD of the mean) and 17 others within this range. In all cases total PS antigen was slightly reduced (77 +/- 18%, M +/- SD) with a more marked decrease of free antigen (59 +/- 17%) and normal values of C4bBP. Levels of PS activity were greatly reduced and lower than those of free antigen with a mean ratio of PS activity to free antigen of 0.6. These abnormalities were associated with significantly high concentrations of fibrinogen D-dimers. PS deficiency in SCD may be at least partly due to adsorption of free PS to aminophospholipids abnormally expressed on sickle cells membranes, microvesicles and activated platelets, while the discrepancy between PS activity and free antigen could reflect proteolytic inactivation of PS by traces of thrombin.

Adolescent↗
PubMedDate not supplied

Cytokines in HIV infection.

Human immunodeficiency virus infection leads to a deregulated production of a number of cytokines. Some of them (IL-1, IL-6, TNF-alpha, interferon-gamma) are produced in increased amounts in vivo, whereas the production of IL-2 is decreased. This latter abnormality plays a pivotal role in the establishment of the immunodeficiency. Some cytokines (IL-1, IL-6, TNF-alpha) stimulate the in vitro replication of HIV, whereas others (mainly the interferons) inhibit it. The effect of cytokines in vivo in the spreading of HIV remains, however, largely unknown. Cytokines may also be involved in the development of many clinical manifestations associated with HIV infection. IL-1, IL-6 and TNF-alpha may play a role in tissue damages associated with opportunistic infections, in HIV-related encephalopathy and in cachexia. Cytokines, mainly IL-6, IL-10 and IL-13, may stimulate the growth of malignant cells during Kaposi sarcoma or lymphomas. Better knowledge of the role of cytokines during HIV infection should allow new therapeutic approaches based on the use of either recombinant cytokines or specific antagonists, with the aim of limiting both HIV spreading and the clinical manifestations of this infection.

Cytokines↗
PubMedDate not supplied

[Evaluation of the blood analyzer Beckman Coulter LH 750: analytic performance, decision rules].

We evaluated the new analyzer Beckman Coulter, an instrument dedicated to the cell blood count (CBC) and to the white blood cell (WBC) differential (including nucleated red blood cells (NRBCs)) over a global one month period, with three purposes: 1) evaluation of the analytical performance (precision, reproducibility, contamination, linearity); 2) accuracy of numerical results, by comparison to the laboratory instrument (CBC and WBC diff) or to the blood smear (NRBCs, low platelets); 3) evaluation, in terms of sensitivity and specificity, a set of abnormality messages built from the suspect flags and a few quantitative abnormalities. The analytical performances were found satisfactory. The WBC and platelet ranges of linearity were wider than in the GEN.S, as stated in the system specifications. However, the lack of adequate biological material made impossible the study of the whole mentioned linearity range. The accuracy of the CBC and differential parameters, as well as of reticulocytes, was studied with the Coulter GEN.S as reference instrument. The coefficients of correlation and the regression lines showed that the LH 750 results were similar to the GEN.S results. Furthermore, samples with thrombocytopenia and circulating NRBCs were evaluated and compared to the result obtained with microscopic lecture. The results showed a good relationship between platelets results given by the GEN.S and manual count leading to appropriate decision of transfusion. The correlation between GEN.S and manual count of NRBC was estimated as satisfactory. We used the LH 750 software to create conditional rules on the basis of qualitative and quantitative criteria, in order to define and enter a message system for detection of abnormalities. Our study showed that such a system flagged 95.7% of morphological abnormalities with a rate of unnecessary slide review (absence of any morphological abnormality on the blood smear) estimated at 8.3%. Furthermore, in 86% of the abnormalities studied, the relevant message was triggered. The Beckman Coulter LH 750 thus appeared as suitable in terms of validation efficiency.

Adult↗