Research Interests: Cancer, Fluorescence Microscopy, Cancer Biology, Confocal Microscopy, Angiogenesis, and 15 moreBiological Sciences, RNA interference, Tumor microenvironment, Humans, Basement Membrane, Endothelial Cells, Animals, Male, Tumor, HeLa cells, Neoplasms, Podosomes, Vascular Endothelial Function, Matrix Metalloproteinase, and Laminin
There is growing interest in the association of radiotherapy and immunotherapy for the treatment of solid tumors. Here, we report an extremely effective combination of local irradiation (IR) and Shiga Toxin B (STxB)-based human... more
There is growing interest in the association of radiotherapy and immunotherapy for the treatment of solid tumors. Here, we report an extremely effective combination of local irradiation (IR) and Shiga Toxin B (STxB)-based human papillomavirus (HPV) vaccination for the treatment of HPV-associated head and neck squamous cell carcinoma (HNSCC). The efficacy of the irradiation and vaccine association was tested using a model of HNSCC obtained by grafting TC-1/luciferase cells at a submucosal site of the inner lip of immunocompetent mice. IR and the STxB-E7 vaccine acted synergistically with both single and fractionated irradiation schemes, resulting in complete tumor clearance in the majority of the treated mice. A dose threshold of 7.5 Gy was required to elicit the dramatic antitumor response. The combined treatment induced high levels of tumor-infiltrating, antigen-specific CD8+ T cells, which were required to trigger the antitumor activity. Treatment with STxB-E7 and IR induced CD8+ ...
Research Interests:
A factor X molecular variant was identified in a 55-year-old woman at a routine preoperative coagulation screening. Plasma factor X antigen was normal, whereas factor X activity was decreased when factor X was activated by either the... more
A factor X molecular variant was identified in a 55-year-old woman at a routine preoperative coagulation screening. Plasma factor X antigen was normal, whereas factor X activity was decreased when factor X was activated by either the extrinsic pathway (21%), the intrinsic pathway (21%) or the factor X activator from Russell viper venom, RVV-X (26%). Factor XMarseille was isolated from plasma by immunoaffinity chromatography and compared with normal factor X purified by the same method. Activation of factor XMarseille by factor IXa or by RVV-X in a purified system showed that the rate of cleavage was decreased, whereas once produced, factor XaMarseille had a normal catalytic efficiency for either the peptide substrate S-2765 (D-Arg-Gly-Arg-NH-Np) or prothrombin. The rate of inhibition of factor XaMarseille by antithrombin III was also normal. Defective proteolysis of factor XMarseille by factor IXa or by RVV-X was the consequence of a threefold decrease in the kcat for the activation of factor XMarseille while the Km of RVV-X or factor IXa for factor X was normal. We have determined the molecular basis of the defect in the factor XMarseille gene by amplification of all eight exons, single-strand conformational polymorphism analysis of the amplified exons and subsequent sequence analysis. The patient was homozygous for a T-->C mutation in exon VIII, resulting in the substitution of Ser334 by proline. From comparison of three-dimensional models of various serine proteases, it appears that Ser334 is located within a surface-exposed variable region of factor X. This observation suggests that the Ser334-->Pro mutation either is responsible for a misalignment of the active sites of specific factor X activators in close proximity to the cleavage site, or that the Ser-->Pro mutation alters the spatial orientation of the cleavage site by nonlocal modifications of factor X structure.
Research Interests:
Background: Therapeutic use of unfractionated heparin and low molecular weight heparins (LMWHs) is limited by hemorrhagic adverse effects. We compared the antithrombotic effect of LMW fucoidan (LMWF) and LMWH in an experimental model.... more
Background: Therapeutic use of unfractionated heparin and low molecular weight heparins (LMWHs) is limited by hemorrhagic adverse effects. We compared the antithrombotic effect of LMW fucoidan (LMWF) and LMWH in an experimental model. Methods: Thrombosis was induced in femoral arteries of male New Zealand White rabbits by in situ induction of endothelial apoptosis with staurosporine (10–5M for 30 min). Starting
Research Interests:
Research Interests:
Purpose: Factor V Leiden and factor II 20210A are inherited disorders of the clotting system that occur frequently in patients with deep vein thrombosis. We conducted this study to determine whether these factors are also common in... more
Purpose: Factor V Leiden and factor II 20210A are inherited disorders of the clotting system that occur frequently in patients with deep vein thrombosis. We conducted this study to determine whether these factors are also common in patients with pulmonary embolism.Subjects and Methods: We determined the prevalence of factor V Leiden and factor II 20210A in 773 consecutive patients with
Research Interests:
The structure of red blood cell (RBC) membranes in homozygous sickle cell disease (SCD) is significantly disturbed, with an increased exposure of aminophospholipids (phosphatidylserine and phosphatidylethanolamine) at the outer surface,... more
The structure of red blood cell (RBC) membranes in homozygous sickle cell disease (SCD) is significantly disturbed, with an increased exposure of aminophospholipids (phosphatidylserine and phosphatidylethanolamine) at the outer surface, responsible for a procoagulant activity of SS RBCs. Aminophospholipids are known not only to promote procoagulant reactions, but also to support inhibition of blood coagulation by the protein C system. The aim of the present study was to examine whether SS RBCs could serve as a catalytic surface for the inactivation of factor Va by activated protein C (APC). Venous blood was obtained from 19 consecutive SS patients and 13 controls (AA). In all SS patients, the amount of phosphatidylserine exposed at the outer surface of RBCs was increased compared with controls, as demonstrated by a prothrombinase assay. In addition, SS RBCs significantly (P < 0.0001) increased the rate of FVa inactivation by APC: the mean values (and ranges) of the factor Va inactivation rates were 30 (0-57) vs 9.5 (0-32) mmol Vai/min/mol APC for SS RBCs and normal RBCs respectively. Our results indicate that SS RBCs provide a catalytic surface for the negative control of blood coagulation, which may partially control the procoagulant activity of these cells.
Research Interests:
In Caucasians, the R506Q mutation in exon 10 of the factor V gene (FV Leiden) confers an increased risk of thromboembolism. We have scanned this region of the gene for possible mutations in 450 subjects from populations at risk for sickle... more
In Caucasians, the R506Q mutation in exon 10 of the factor V gene (FV Leiden) confers an increased risk of thromboembolism. We have scanned this region of the gene for possible mutations in 450 subjects from populations at risk for sickle cell disease (SCD). The R506Q mutation was absent in subjects from sub-Saharan Africa, whereas its allelic frequency was 2.5%
Research Interests: Genetics, Human Genetics, Polymorphism, Complementary and Alternative Medicine, Sickle Cell Anemia, and 13 moreRisk, Molecular Genetics, Humans, Europe, Genetic Polymorphisms, Sickle Cell Disease, Risk factors, Thrombosis, Sub Saharan Africa, Risk Factors, West Indies, Coagulation Factors, and Allele Frequency
THE ENDOTHELIUM IS NOWADAYS DESCRIBED AS AN ENTIRE ORGAN THAT REGULATES VARIOUS PROCESSES: vascular tone, coagulation, inflammation, and immune cell trafficking, depending on the vascular site and its specific microenvironment as well as... more
THE ENDOTHELIUM IS NOWADAYS DESCRIBED AS AN ENTIRE ORGAN THAT REGULATES VARIOUS PROCESSES: vascular tone, coagulation, inflammation, and immune cell trafficking, depending on the vascular site and its specific microenvironment as well as on endothelial cell-intrinsic mechanisms like epigenetic changes. In this review, we will focus on the control of the adaptive immune response by the tumor vasculature. In physiological conditions, the endothelium acts as a barrier regulating cell trafficking by specific expression of adhesion molecules enabling adhesion of immune cells on the vessel, and subsequent extravasation. This process is also dependent on chemokine and integrin expression, and on the type of junctions defining the permeability of the endothelium. Endothelial cells can also regulate immune cell activation. In fact, the endothelial layer can constitute immunological synapses due to its close interactions with immune cells, and the delivery of co-stimulatory or co-inhibitory signals. In tumor conditions, the vasculature is characterized by an abnormal vessel structure and permeability, and by a specific phenotype of endothelial cells. All these abnormalities lead to a modulation of intra-tumoral immune responses and contribute to the development of intra-tumoral immunosuppression, which is a major mechanism for promoting the development, progression, and treatment resistance of tumors. The in-depth analysis of these various abnormalities will help defining novel targets for the development of anti-tumoral treatments. Furthermore, eventual changes of the endothelial cell phenotype identified by plasma biomarkers could secondarily be selected to monitor treatment efficacy.
In the present study we examined if, among other mechanisms, the abnormal exposure of phosphatidylserine at the surface of sickle red blood cells (RBCs) contributes to the hypercoagulability which characterizes homozygous sickle cell... more
In the present study we examined if, among other mechanisms, the abnormal exposure of phosphatidylserine at the surface of sickle red blood cells (RBCs) contributes to the hypercoagulability which characterizes homozygous sickle cell disease (SCD). The question was addressed by comparison of the procoagulant properties of RBCs from subjects with various phenotypes (SS, SC and AS) that differ in clinical presentation. As previously reported, SS-RBCs accelerated the prothrombin activation by factor Xa, by decreasing the Km of the reaction compared to normal RBCs. SC-RBCs and AS-RBCs also promoted prothrombin activation although their procoagulant properties were milder compared to SS-RBCs. A significant increase of the thrombin-antithrombin complexes was observed in SS subjects. Prothrombin fragment 1+2 (F1+2) was elevated in half of the SS subjects, but the difference with controls did not reach significance. Elevated levels of thrombin-antithrombin complexes were observed in a number of SC (4/11) and AS (3/12) subjects, but the difference with controls was not significant. A significant correlation was observed between the plasma levels of thrombin-antithrombin complexes in the subjects with SS, AS and AA phenotypes, and the procoagulant properties of RBCs. Our results strongly suggest that the procoagulant properties which characterize SS-RBCs also affect SC-RBCs and AS-RBCs, and that exposure of phosphatidylserine by RBCs contributes to the hypercoagulable state observed in SCD.
Research Interests:
Research Interests: Nuclear Magnetic Resonance, Magnetic Resonance Spectroscopy, Free Radical, Biological Sciences, Thrombin, and 9 moreMethylation, Physical sciences, Anticoagulants, Molecular Mass, Molecular weight, Chemical Modification, Low molecular weight, Biochemistry and cell biology, and Activated partial thromboplastin time
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Iron deficiency is typically associated with microcytic anemia and thrombocytosis. It is a very uncommon cause of thrombocytopenia. A 17-year-old female presented with marked fatigue and dyspnea on exertion. Review of systems was only... more
Iron deficiency is typically associated with microcytic anemia and thrombocytosis. It is a very uncommon cause of thrombocytopenia. A 17-year-old female presented with marked fatigue and dyspnea on exertion. Review of systems was only remarkable for abundant menstruations during the past two years. The hemogram revealed a profound microcytic anemia (4.4 g/dL, mean corpuscular volume [MCV] 49 fL) and a thrombocytopenia (33 G/L). Marked iron deficiency was also present: ferritinemia <3 μg/L. Investigations did not find any cause of iron deficiency anemia other than excessive menstrual loss. Bone marrow examination showed an increase number of megakaryocytes, compatible with an immune thrombocytopenia purpura. Iron supplementation completely normalized the platelet count within 48 hours. Iron affects thrombopoiesis. Because the number of megakaryocytes may then increase in the bone marrow, "iron deficiency thrombocytopenia" may be falsely diagnosed as immune thrombocytopen...
Research Interests:
Sunitinib, a multitargeted tyrosine-kinase inhibitor, extends survival of patients with metastatic renal cell carcinoma (mRCC) and gastrointestinal stromal tumours. Between October 2005 and March 2007, we retrospectively reviewed blood... more
Sunitinib, a multitargeted tyrosine-kinase inhibitor, extends survival of patients with metastatic renal cell carcinoma (mRCC) and gastrointestinal stromal tumours. Between October 2005 and March 2007, we retrospectively reviewed blood glucose level variations associated with sunitinib therapy in patients treated for mRCC. Nineteen of the patients had type II diabetes. All 19 patients had a decrease in blood glucose level (mean 1.77 mmol l(-1)) after 4 weeks of treatment. This was followed by re-elevation in the 2-week rest period. After two cycles of sunitinib administration, two patients had stopped blood glucose-lowering drugs whereas five other patients had normalised their blood glucose level. On the basis of pre-clinical data, we hypothesise that several mechanisms could be involved in this process, such as capillary regression of pancreatic islets, IGF-1 modulation through HIF1-alpha or NF-kappaB activation. In addition, a decrease of glucose uptake in the context of concomit...
Research Interests:
We report the case of a 20 years old man presenting two episodes of hematemesis. The patient was known to suffer from depression and was treated with sertraline (Zoloft®) for 6 months at the dosage of 100 mg/day. No endoscopic and... more
We report the case of a 20 years old man presenting two episodes of hematemesis. The patient was known to suffer from depression and was treated with sertraline (Zoloft®) for 6 months at the dosage of 100 mg/day. No endoscopic and radiological abnormality was found. The haemostasis report was normal. Exploration of platelet function was in favor of an abnormality of platelet secretion as evidenced by low epinephrine-induced aggregation, a slightly reduced aggregation for following agonists: TRAP, ADP 5 μM and 10 μM, and a longer latency to collagen. The diagnosis of an acquired platelet disorder was strongly suspected and in particular an acquired platelet disorder induced by selective serotonin reuptake inhibitors that is known to interfere with platelet activation pathways involving serotonin.
Research Interests:
We present a case series of seven patients with metastatic renal cell carcinoma treated with bevacizumab (10mg/kg) in combination with sunitinib 25–50mg as salvage therapy after disease progression under sunitinib monotherapy. Two... more
We present a case series of seven patients with metastatic renal cell carcinoma treated with bevacizumab (10mg/kg) in combination with sunitinib 25–50mg as salvage therapy after disease progression under sunitinib monotherapy. Two patients had a partial response, four had stable disease, and one patient had disease progression. After a median follow-up of 17.2 mo, median progression-free survival and overall survival
Research Interests:
Research Interests: Oncology, Molecular Medicine, Cancer, Cell Cycle, Macrophages, and 7 moreApoptosis, Humans, Mice, Animals, Cell, Gene, and Cell Proliferation
Research Interests:
Research Interests: Cancer, Fluorescence Microscopy, Cancer Biology, Confocal Microscopy, Angiogenesis, and 15 moreBiological Sciences, RNA interference, Tumor microenvironment, Humans, Basement Membrane, Endothelial Cells, Animals, Male, Tumor, HeLa cells, Neoplasms, Podosomes, Vascular Endothelial Function, Matrix Metalloproteinase, and Laminin
Research Interests:
Fucoidans are sulfated polysaccharides extracted from brown marine algae. A purified fucoidan fraction exhibits the same venous antithrombotic activity as heparin in rabbits, but with a lower anticoagulant effect. Because of its... more
Fucoidans are sulfated polysaccharides extracted from brown marine algae. A purified fucoidan fraction exhibits the same venous antithrombotic activity as heparin in rabbits, but with a lower anticoagulant effect. Because of its heparin-like structure, we postulated that fucoidan might modulate heparin-binding angiogenic growth factor activity. We thus studied its effect, at antithrombotic concentrations, on fibroblast growth factor (FGF)-2-induced proliferation and differentiation of human umbilical vein endothelial cells. The fucoidan effect on endothelial cell differentiation was evaluated by studying the expression of surface proteins (i.e. integrin, adhesion molecule) known to be modulated by FGF-2 and involved in angiogenesis, and by quantifying closed areas delimited by vascular tubes formed on reconstituted basement membrane. Fucoidan had no modulatory effect on the mitogenic activity of FGF-2, but significantly increased tubular structure density induced by FGF-2. Fucoidan alone increased alpha(6) integrin subunit expression with only partially organized tubular structure. In the presence of FGF-2, fucoidan enhanced alpha(6), beta(1) and PECAM-1 and inhibited alpha(v)beta(3) integrin expression. Heparin had no effect in these systems. The most striking effect of fucoidan was observed on alpha(6) expression and tube formation was abolished by monoclonal anti-alpha(6) antibodies. Fucoidan plus FGF-2 effect on alpha(6) expression was markedly decreased by monoclonal anti-FGF-2 antibodies, indicating that fucoidan acts mainly via FGF-2. These results show that, at antithrombotic concentrations, contrary to heparin, fucoidan can enhance vascular tube formation induced by FGF-2 with a modulation of the expression of surface proteins (mainly alpha(6)) involved in angiogenesis.
Research Interests:
Research Interests: Rheumatology, Immunology, Flow Cytometry, Humans, Systemic Lupus Erythematosus, and 15 moreEndothelial Cells, Female, Male, Vascular endothelium, Endothelial dysfunction, Clinical Sciences, Aged, Middle Aged, Adult, Public health systems and services research, Biological markers, Disease Activity, Autoantibodies, Case Control Studies, and Severity of Illness Index
Research Interests:
Basic fibroblast growth factor (FGF-2) activates its high-affinity receptors (FGFRs) but also acts through interaction with heparan sulfate proteoglycans (HSPG). Exogenous polysaccharides also modulate the angiogenic activity of FGF-2. We... more
Basic fibroblast growth factor (FGF-2) activates its high-affinity receptors (FGFRs) but also acts through interaction with heparan sulfate proteoglycans (HSPG). Exogenous polysaccharides also modulate the angiogenic activity of FGF-2. We investigated the effect and mechanism of action of a low molecular weight fucoidan derivative (LMWF) on tube formation by human endothelial cells. LMWF has a better arterial antithrombotic potential in animals than low molecular weight heparin (LMWH). After stimulation of human umbilical vein endothelial cells (HUVEC) by FGF-2 and LMWF (or LMWH), we observed 1) using flow cytometry, an increase in the amount of the alpha6 integrin subunit; 2) using quantitative reverse transcription-polymerase chain reaction, an increase in alpha6 mRNA (higher with LMWF than with LMWH); and 3) using a Matrigel model, an increase in vascular tube formation (also higher with LMWF than with LMWH). A direct link between alpha6 overexpression and vascular tube formation was confirmed by use of an anti-alpha6 antibody: in its presence, there was no capillary network formation on Matrigel. Unexpectedly, an anti-FGFR blocking antibody had no effect on alpha6 over-expression, whereas stripping off the heparan sulfate with heparitinases abolished overexpression. Overall, our data suggest that FGF-2 stimulates alpha6 over-expression in HUVEC, through HSPG but independently from FGFR, and that LMWF (or LMWH) modulates this interaction. Expression of heparan sulfate proteoglycan increases after ischemic injury. Given its antithrombotic properties and its ability to potentiate tube formation of endothelial cells, LMWF may have to be considered for revascularization of ischemic areas.
Research Interests:
Endogenous phosphatidylserine (PS) exposure and lipid transport activity have been investigated for seven unrelated cases of Rhnull erythrocytes. Endogenous PS exposure was measured by prothrombinase activity. Out of six cases studied,... more
Endogenous phosphatidylserine (PS) exposure and lipid transport activity have been investigated for seven unrelated cases of Rhnull erythrocytes. Endogenous PS exposure was measured by prothrombinase activity. Out of six cases studied, two Rhnull samples exhibited abnormal aminophospholipid exposure, as suggested by the measurement of a lower Km of factor Xa for prothrombin. Aminophospholipid translocase activity was measured through the transbilayer redistribution of spin-labelled analogues of phospholipids. Provided that incubation conditions allow the maintainance of intracellular ATP level, no difference was observed between Rhnull and control erythrocytes, clearly indicating that the aminophospholipid translocase and Rh polypeptides are different molecular species.
Research Interests:
Research Interests:
Little is known about residual abnormalities after pulmonary embolism (PE). To assess risk factors and the clinical significance of perfusion defects in patients with PE. Consecutive patients receiving at least 3 months of anticoagulant... more
Little is known about residual abnormalities after pulmonary embolism (PE). To assess risk factors and the clinical significance of perfusion defects in patients with PE. Consecutive patients receiving at least 3 months of anticoagulant for an acute PE were included in a prospective cohort study. Ventilation/perfusion lung scan, echocardiography, 6-min walk test, thrombophilia and hemostatic variables were performed 6-12 months after PE. Perfusion defect was defined as a perfusion defect in at least two segments. Seventy-three out of 254 patients (29%) had perfusion defects during follow-up (median 12 months) and were more likely to have dyspnea, had a higher systolic pulmonary arterial pressure [39 mmHg (SD) (12) vs. 31 mmHg (8); P &lt; 0.001] and walked a shorter distance during the 6-min walk test [374 m (122) vs. 427 m (99); P = 0.004]. Age [odds ratio (OR) 1.35; 95% confidence interval (CI), 1.11-1.63], the time interval between symptom onset and diagnosis (OR, 1.17; 95% CI, 1.04-1.31), pulmonary vascular obstruction at the onset of PE (OR, 1.34; 95% CI, 1.16-1.55) and previous venous thromboembolism (OR 2.06; 95% CI, 1.03-4.11) were independent predictors of perfusion defect after treatment of acute PE. Total tissue factor pathway inhibitor concentration was associated with perfusion defects. Perfusion defects are associated with an increase in pulmonary artery pressure (PAP) and functional limitation. Age, longer times between symptom onset and diagnosis, initial pulmonary vascular obstruction and previous venous thromboembolism were associated with perfusion defects.