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Bernadette Boval

Publications and source records attributed to Bernadette Boval.

8 recordsLinked to original sources
PubMed2005

Defective collagen-induced platelet activation in two patients with malignant haemopathies is related to a defect in the GPVI-coupled signalling pathway.

The occurrence of a thrombocytopathy concomitantly to the development of a malignant haemopathy has been reported for some time, but little is known about the mechanism(s) involved in the platelet dysfunction. Platelet glycoprotein VI (GPVI) has now been identified as a principal platelet receptor for collagen. In this paper, we report the cases of two patients with a myelodysplasia and a B lymphopathy, respectively, who presented with thrombocytopathy in relation to a defective GPVI-mediated platelet reactivity to collagen. Thus, with regard to the different steps of adhesion, activation secretion or aggregation, patients' platelet responses to collagen and to the GPVI specific agonists, collagen related peptide (CRP) or convulxin were null or dramatically impaired. Platelet responses to other agonists ADP, TRAP, Arachidonic acid were normal or showed only a moderate decrease. GPVI content was repeatedly normal, and binding of specific ligands, such as convulxin, satisfactory. Nevertheless, specific activating monoclonal antibodies and convulxin failed to induce platelet secretion; collagen, CRP or convulxin were unable to provoke calcium mobilisation. Furthermore, using a perfusion chamber model, we showed that ex vivo collagen-induced thrombi formation was very impaired. Taken together, these data provide evidence, for the first time, of an acquired defect in GPVI-mediated platelet reactivity to collagen, which reflects data observed in constitutional GPVI deficiencies, in two patients with malignant haemopathies.

Aged↗
PubMed2004

Ex vivo differentiated endothelial and smooth muscle cells from human cord blood progenitors home to the angiogenic tumor vasculature.

OBJECTIVES: Recent studies have provided increasing evidence that postnatal neovascularization does not rely exclusively on sprouting of preexisting vessels, but also involves bone marrow-derived circulating endothelial precursors (BM-EPCs). Animal studies revealed that neovascularization of ischemic tissue can be enhanced by BM-EPCs transplantation. But a possible limitation to the use of vascular precursors for therapeutic angiogenesis is the relatively low number of these cells. In this study, we demonstrate that ex vivo expanded differentiated endothelial cells (ECs) and smooth muscle cells (SMCs), may home to the tumor vasculature allowing targeting of transgene expression to the neoangiogenic site. METHODS: Mononuclear cells (MNCs) or CD34+ -enriched cells were purified from cord blood. We have defined culture conditions in which we observed two types of clones easily differentiated according to their morphology: cobblestone or spindle-shaped. Phenotypic characterization was assessed by immunocytochemistry, flow cytometry analysis and polymerase reaction with reverse transcription. Formation of capillary-like network in vitro was studied in three-dimensional collagen culture. And recruitment of these cells to a tumoral neoangiogenic site was assessed into tumor-bearing Severe Combined Immunodeficient (SCID) mouse model. RESULTS: The cobblestone cells uniformly positive for CD31, VE-cadherin, vWF, VEGF R1 and R2, ecNOS and incorporating acetylated LDL were ECs. Spindle-shaped cells expressed alpha-smooth muscle actin (alpha-SMA), Smooth Muscle Heavy Chain (SMHC), SM22 and calponin. They also displayed a carbachol-induced contractility in a medium containing IGF1. So we concluded that spindle-shaped cells were SMCs. ECs and SMCs interacted with each other to form a capillary like network in three-dimensional type I collagen culture. Moreover, these ex vivo differentiated cells are able to home to the tumor vasculature. CONCLUSION: We provide evidence that progenitors for ECs and SMCs circulate in human cord blood and differentiate into functional ECs and SMCs. These differentiated cells could provide a biomaterial for vascular cell therapy, because of their homing capacity to the neovascularization site.

Animals↗
PubMed2004

Platelet activation and aggregation profile in prolonged external ventricular support.

BACKGROUND: Platelet function plays a major role in the understanding of thromboembolic events in prolonged mechanical support. We studied the platelet activation, platelet aggregation profile, and efficacy of aspirin in patients in whom an external ventricular assist device had been implanted. PATIENTS AND METHODS: Fifteen patients were studied prospectively up to 6 weeks after implantation of the same type of ventricular assist device. Platelet function was studied weekly before daily aspirin administration. Aspirin efficacy was tested ex vivo by measuring platelet aggregation triggered by arachidonic acid. Flow cytometry was used to quantify the spontaneous and induced (adenosine diphosphate stimulation) expression of glycoproteins alphaIIbbeta3, Ibalpha, and CD62P on platelet membranes. The plasma levels of von Willebrand factor (von Willebrand factor activity and von Willebrand factor antigen) and fibrinogen were also determined. RESULTS: Six of the 15 patients (26%) maintained an arachidonic acid-induced platelet aggregation despite daily aspirin treatment (250 mg). CD62P values remained increased during a 5-week postoperative period. Spontaneous levels of glycoproteins alphaIIbbeta3 and Ibalpha on platelet membranes remained within a normal range with a preserved reactivity. The plasma levels of fibrinogen and von Willebrand factor remained increased during the entire study period. CONCLUSION: In patients with an implanted external ventricular assist device, the platelet activation profile displays a persistent activation with a preserved reactivity associated with a persistent high inflammatory state and endothelial activation.

Adolescent↗
PubMed2004

Histocompatibility leukocyte antigen-D related expression is specifically altered and predicts mortality in septic shock but not in other causes of shock.

Although the expression of monocyte histocompatibility leukocyte antigen (HLA)-DR has been shown to be decreased during human sepsis, its level of expression in other nonseptic critical conditions is unclear. The aim of this study was to compare the level of HLA-DR expression on circulating monocytes among patients with septic, hemorrhagic, and cardiogenic shocks and severe sepsis without shock. At admission, HLA-DR expression was exclusively decreased in patients with septic shock (n = 30; P < 0.001), whereas the expression was similar between the other studied groups: cardiogenic shock (n = 16), hemorrhagic shock (n = 11), severe sepsis without shock (n = 18), and healthy volunteers (n = 8). HLA-DR expression was not predictive for overall mortality, but at day 1, an HLA-DR expression of less than 14 of mean fluorescence intensity (that corresponds to 40% labeled monocytes) was predictive of mortality exclusively in patients with septic shock (odds ratio, 11.4 and 95% confidence interval, 1.7; 78.4; P < 0.008). Catecholamine infusion, mechanical ventilation, positive blood culture, and number of units of blood or plasma transfused did not correlate with decreased HLA-DR expression. Thus, the decrease in HLA-DR expression is specific to septic shock and is associated, in septic shock patients, with increased mortality risk.

Adult↗
PubMed2002

A Leu7Pro mutation in the signal peptide of platelet glycoprotein (GP)IX in a case of Bernard-Soulier syndrome abolishes surface expression of the GPIb-V-IX complex.

This paper describes the molecular defect of the second case of Bernard-Soulier syndrome, initially reported in 1957. Analysis of the patient's platelets by flow cytometry and Western blotting failed to detect surface expression of any of the four subunits of the glycoprotein (GP)Ib-V-IX complex and revealed small amounts of intracellular GPIbalpha, GPIbbeta and GPV but no GPIX. DNA sequencing revealed a novel missense mutation in the GPIX gene which replaced Leu (CTG) by Pro (CCG) at position 7 of the signal peptide. This mutation is, to date, the only known example of a leader sequence defect in Bernard-Soulier syndrome. The change occurred in a prototypic alpha-helical hydrophobic core region, typically enriched in leucine and devoid of proline residues. Co-transfection of GPIXPro7 with normal GPIbalpha and GPIbbeta into Chinese hamster ovary cells reproduced the platelet phenotype, resulting in no detectable GPIX, low intracellular levels of GPIbalpha and GPIbbeta, and an absence of surface expression. This mutation presumably leads to an abnormal conformation and, hence, incorrect insertion of GPIX into the endoplasmic reticulum and/or to defective signal peptide cleavage, both of which are required for correct transport to the cell membrane. This provides further evidence for a critical role of GPIX in controlling biosynthesis of the GPIb-IX complex.

Animals↗
PubMed2002

AGEs bind to mesothelial cells via RAGE and stimulate VCAM-1 expression.

BACKGROUND: Excess advanced glycation end-products (AGEs) are formed during renal failure, and AGE formation also may be connected with the high glucose concentration of peritoneal dialysis (PD) fluids. To determine the effect of human peritoneal mesothelial cell (HPMC) exposure to glycated proteins, we studied the HPMC receptor of AGE expression (RAGE), and analyzed the results of AGE-RAGE interaction on adhesion molecule expression and leukocyte binding. METHODS: RAGE was detected by FACS analysis, and RAGE mRNA by reverse transcription-polymerase chain reaction (RT-PCR). Vascular and intercellular cell adhesion molecule (VCAM-1 and ICAM-1) expression was measured by a known radiometric technique under basal conditions, after the addition of an AGE-specific compound, Nepsilon-carboxylmethyllysine (CML-albumin). Leukocyte adhesion on HPMC was analyzed by videomicroscopy after HPMC stimulation. RESULTS: RAGE protein was detected on HPMC, and RAGE mRNA was evidenced by RT-PCR. VCAM-1 expression was stimulated by CML-albumin (P < 0.01), while ICAM-1 was unchanged. By blocking the AGE-RAGE interaction, anti-RAGE antibodies or recombinant RAGE inhibited the increase in VCAM-1 expression. CML-albumin stimulation potentiated leukocyte adhesion to HPMC (P < 0.001). This effect was prevented by the incubation of leukocytes with recombinant VCAM-1 (P < 0.001). CONCLUSIONS: AGE binding to RAGE stimulated mesothelial cell activity, and resulted in the overexpression of VCAM-1, a structure for leukocyte adhesion. The AGE-RAGE interaction resulted in HPMC activation, which may promote local inflammation, and thus is implicated in the peritoneal injury found in long-term PD patients.

Adult↗
PubMedDate not supplied

Management of intracranial hemorrhage in patients with mechanical circulatory support: a role for low-molecular-weight heparins?

Patients on mechanical circulatory support are at high risk of bleeding, particularly intracranial hemorrhage (ICH). The management of ICH in patients needing anticoagulation and antiplatelet therapies remains a challenge. We report our initial experience of ICH management with low-molecular-weight heparin in patients with mechanical circulatory support, without bleeding or thromboembolic complications.

Aged↗