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Biomedical subjects

Y Gruel

Publications and source records attributed to Y Gruel.

At least 19 recordsLinked to original sources
PubMed2005

Expression and methylation status of tissue factor pathway inhibitor-2 gene in non-small-cell lung cancer.

Tissue factor pathway inhibitor-2 (TFPI-2) is a Kunitz-type serine proteinase inhibitor that inhibits plasmin-dependent activation of several metalloproteinases. Downregulation of TFPI-2 could thus enhance the invasive potential of neoplastic cells in several cancers, including lung cancer. In this study, TFPI-2 mRNA was measured using a real-time PCR method in tumours of 59 patients with non-small-cell lung cancer (NSCLC). Tumour TFPI-2 mRNA levels appeared well correlated with protein expression evaluated by immunohistochemistry and were 4-120 times lower compared to those of nonaffected lung tissue in 22 cases (37%). Hypermethylation of the TFPI-2 gene promoter was demonstrated by restriction enzyme-polymerase chain reaction in 12 of 40 cases of NSCLC (30%), including nine of 17 for whom tumour TFPI-2 gene expression was lower than in noncancerous tissue. In contrast, this epigenetic modification was shown in only three of 23 tumours in which no decrease in TFPI-2 synthesis was found (P=0.016). Decreased TFPI-2 gene expression and hypermethylation were more frequently associated with stages III or IV NSCLC (eight out of 10, P=0.02) and the TFPI-2 gene promoter was more frequently hypermethylated in patients with lymph node metastases (eight out of 16, P=0.02). These results suggest that silencing of the TFPI-2 gene by hypermethylation might contribute to tumour progression in NSCLC.

Adult↗
PubMed2005

Improved PCR method for amplification of GC-rich DNA sequences.

Most housekeeping genes, tumor-suppressor genes, and approx 40% of tissue-specific genes contain G+C sequences in their promoter region that were very difficult to amplify. In this report, we propose an improved polymerase chain reaction (PCR) method to be used for successful amplification of the tissue factor pathway inhibitor (TFPI)-2 gene promoter region that exhibit >70% G+C content in a sequence of approx 300 bp and a complete CpG island region spanning exon 1, the three transcription initiation sites, and the translation start site. Therefore, this method can be recommended to amplify other GC-rich genomic templates.

Base Sequence↗
PubMed2004

[Heparin-induced thrombocytopenia. Pathogenesis, diagnosis and treatment].

INTRODUCTION: Heparin-induced thrombocytopenia is due to the development of IgG antibodies specific to platelet factor 4. More frequently observed after administration of unfractionated heparin, this complication is characterized by a delayed decrease in platelet count (after the 5th day of treatment) associated with venous and/or arterial thromboses. CURRENT KNOWLEDGE AND KEY POINTS: It is often difficult to discard another potential cause for thrombocytopenia and to demonstrate by Elisa or platelet activation tests the presence of heparin-dependent antibodies is therefore mandatory in every patient. Withdrawal of heparin treatment is always necessary as well as the administration of an alternative antithrombotic agent. Danaparoid sodium (mixture of glycosaminoglycanes mainly with anti-Xa activity) or lepirudin (a recombinant hirudin with only antithrombin activity) are both recommended but these two drugs are associated with a significant risk of bleeding in case of renal failure. Oral anticoagulants such as coumadin can only be given when platelet count is normalized and if the clinical evolution is favorable. Potent antiplatelet agents (ilomedine or tirofiban) can be used in specific situations necessitating heparin such as extracorporeal circulation. FUTURE PROSPECTS AND PROJECTS: Early administration of coumadin for the treatment of venous thromboembolic disease efficiently prevent the occurrence of heparin-induced thrombocytopenia, which could disappear in the future with a wider use of the new antithrombotic agents, fondaparinux and ximelagatran.

Heparin↗
PubMed2003

Characterization and functional analysis of TFPI-2 gene promoter in a human choriocarcinoma cell line.

Tissue factor pathway Inhibitor-2 (TFPI-2) is associated with extracellular matrices and plays a major role in cell migration and tumor invasion. In this study, a 4.8-kb human TFPI-2 gene 5'-flanking region was isolated, cloned and sequenced. Promoter region analysis revealed a high GC-rich content without canonical TATA and CAAT boxes but three transcription initiation sites were identified. Moreover, several putative binding sites for transcription factors were identified (MyoD, LYF1, NF-Y, GATA, oct-1, AP-1, Sp1, NF1, NF-kappa B and egr-1). To characterize potential regulatory regions, TFPI-2/luciferase promoter constructs were then transfected in human choriocarcinoma JEG-3 cells. We first showed that the minimal TFPI-2 promoter is located between -166 and -111 from the translation start site. Luciferase activity consistently increased after stimulation of JEG-3 cells by phorbol 12-myristate 13-acetate indicating that NF1, NF-kappa B and egr-1/Sp1 binding sites are crucial in inducible TFPI-2 expression. Moreover, negative regulatory regions included AP-1 binding sites were identified. This study demonstrates that the TFPI-2 gene promoter exhibits typical features of a housekeeping gene.

5' Flanking Region↗
PubMed2002

[Association of D-dimer and helicoidal thoracic scanner for diagnosis of pulmonary embolism. Prospective study of 106 ambulatory patients].

OBJECTIVE: Ventilation/perfusion pulmonary scintigraphy (PS), the current mainspring in the diagnosis of pulmonary oedema (PE), is frequently non-conclusive. The objective of this study was to determine, prospectively, the diagnostic value of the association of D-dimers and helicoidal thoracic scanner (HTS) in a continuous series of ambulatory adults with suspected PE and admitted to a cardiologic emergency unit. METHODS: Exclusion criteria were as follows: symptoms or clinical signs of seventy, contraindication for HTS and/or on pulmonary angiography, curative anticoagulant therapy for more than 48 hours, history of PE less than 3 months before or the impossibility of conducting all the examinations with 48 hours. All the patients underwent determination of D-dimers by rapid ELISA test, HTS and 2 reference examinations, venous Doppler of the lower limbs and a PS, completed by pulmonary angiography if the PS did not permit diagnosis and the venous Doppler was negative. RESULTS: One hundred and six patients were selected over a recruitment period of 18 months. The prevalence of PE was of 45% (48/106). Forty-four of the 48 PE of the series were central form. HTS was considered dubious in 10 patients (10.4%, PE+ n = 2, PE- n = 8). The results of D-dimers were negative in only 34.5% patients without PE (20/58). Pulmonary angiography was necessary in 15 patients. The negative and positive predictive values of D-dimers were respectively of 100 and 55.8% (48/86) and those of HTS respectively 100 (46/46) and 92% (46/50). CONCLUSION: The diagnostic strategy of clinical suspicion of PE, starting with determination of D-dimers by rapid ELISA test followed by helicoidal thoracic scanner in the case of a positive result, was particularly effective in this series of patients with a high prevalence of PE. These results must be confirmed in a larger series and in a general emergency unit.

Adult↗
PubMed2002

Comparative evaluation of five different methods for the measurement of plasma factor II levels in carriers of the 20210A prothrombin variant.

The common genetic G to A variation of the prothrombin gene is associated with elevated levels of prothrombin [factor II (FII)] and is recognized as a risk factor for thrombosis. To determine whether one type of assay for plasma FII measurement was more efficient than other assays in displaying high FII levels in 20210A carriers, we compared five methods of measuring FII levels [i.e. an enzyme-linked immunosorbent assay (ELISA), a standard clotting assay, and three chromogenic methods using three different activators: Ecarin, Oxyuranus, and Textarin] in 30 G20210A patients and 30 G20210G controls. Plasma concentrations of factor X and factor VII + factor X were also determined by a clotting procedure. Functional assays were found to be equally efficient in demonstrating significantly higher FII levels in 20210A carriers than in non-carriers (P < 0.0001). With ELISA, the difference observed was less significant (P < 0.005). The specificity of every assay increased with FII cut-off levels; when a cut-off of 115% was applied, sensitivities of functional assays were between 73 and 93%, while sensitivities of ELISA declined dramatically to 33%. FII/factor X and FII/factor VII + factor X ratios were significantly higher in 20210A carriers (P < 0.0001). In conclusion, functional assays are preferentially required for measurements of FII levels in carriers of the 20210A variant.

3' Untranslated Regions↗
PubMed2001

Induction of monocyte tissue factor expression by antibodies to heparin-platelet factor 4 complexes developed in heparin-induced thrombocytopenia.

The pathogenesis of thrombosis in heparin-induced thrombocytopenia (HIT) was studied by investigating whether antibodies to heparin-platelet factor 4 (H-PF4) induced tissue factor (TF) synthesis by monocytes. Plasma from 5 patients with HIT containing IgG to H-PF4 was incubated with peripheral blood mononuclear cells without or with purified PF4 and heparin. Significant TF-dependent procoagulant activity (PCA) expressed by monocytes, measured with a factor Xa-based chromogenic assay, was induced after incubation of each HIT plasma sample. This monocyte PCA required the presence of PF4 and was inhibited by high concentrations of heparin. Furthermore, purified HIT IgG added to whole blood with PF4 and heparin also provoked significant synthesis of TF mRNA by monocytes, demonstrated by RT-PCR, and this effect was not observed with normal IgG. These findings strongly support the hypothesis that antibodies to PF4 developed in HIT trigger the production of tissue factor by monocytes, and this effect could account in vivo for hypercoagulability and thrombotic complications in affected patients.

Blood Coagulation↗
PubMed2001

Acquired inhibitor to factor VIII in a patient with Hodgkin's disease following treatment with interferon-alpha.

We describe a young woman who developed acquired haemophilia after 18 months of interferon (IFN-)-alpha therapy. This patient had been monitored since 1992 for Hodgkin's disease initially treated by chemotherapy. After two relapses, she received intensive chemotherapy followed by an autologous peripheral progenitor cell graft. IFN-alpha was then administered for 18 months. Bleeding of the limbs and tongue occurred 1 month after withdrawal of IFN-alpha and high titres (123 Bethesda units) of autoantibody to factor VIII (FVIII):C were measured. Prednisone (1 mg kg(-1) day(-1)) achieved rapid cessation of the bleeding and FVIII autoantibodies were undetectable 5 months later. This case report suggests that the activated partial thromboplastin time should be regularly checked in every patient treated with IFN-alpha in cases of unexplained bleeding, together testing for antibodies to FVIII if the bleeding is prolonged.

Autoantibodies↗
PubMed2001

Increased plasma fibrinolysis and tissue-type plasminogen activator/tissue-type plasminogen activator inhibitor ratios after ethanol withdrawal in chronic alcoholics.

The effects of alcohol withdrawal on fibrinolysis were studied in 10 middle-aged male chronic alcoholics institutionalized for withdrawal therapy. All patients were sampled on admission [day 1 (D1)] and 21 days after alcohol withdrawal [day 22 (D22)]. The overall plasma fibrinolytic capacity (OFC) was assayed by measuring the ability of patient plasma to generate D-dimers from a standardized fibrin clot, and tissue-type plasminogen activator (t-PA) and t-PA inhibitor (PAI-1) levels were assayed together with serum cholesterol, triglyceride and cholesterol fractions. At D22, the OFC significantly increased in seven patients [D1 = 10 +/- 0.7 microg/h (mean +/- SD), D22 = 17 +/- 7.4 microg/h; P < 0.01], while t-PA and PAI-1 levels decreased in all patients but two (t-PA: D1 = 16.6 +/- 5 ng/ml, D22 = 10.2 +/- 3.8 ng/ml; P < 0.001; and PAI-1: D1 = 46 +/- 39 ng/ml, D22 = 21 +/- 28 ng/ml; P < 0.01). This study clearly demonstrates an increase in overall fibrinolytic activity after alcohol withdrawal, which is mainly due to a decrease in PAI-1 levels. These changes induced by alcohol abstinence might provide clear benefit by reducing the risk of thromboembolic events and particularly of stroke associated with elevated PAI-1 levels described in heavy drinkers.

Adult↗
PubMed2000

[Contribution of platelet aggregation inhibitors in the prevention of complications of atherothrombosis].

RECOGNIZED EFFICACY: Platelet antiaggregats have been used with success for more than twenty years in industrialized countries, participating in reducing the number of complications of atherothrombosis. New compounds have appeared on the market over the last 3 years. CLOPIDOGREL: Clopidogrel is a thienopyridine similar to ticlopidine but with less toxicity, particularly hematological toxicity. Compared with aspirin for secondary prevention of atherothrombotic events in high risk patients, clopidogrel provides a significant 8.7% (p < 0.043) reduction in the relative risk of severe complications: myocardial infarction, ischemic stroke, death due to vascular cause. The most remarkable benefit is obtained in patients with atheromatous arteriopathy of the lower limbs: 23.8% reduction in relative risk. STENT AFTER ANGIOPLASTY: A combination regimen using aspirin and ticlopidine the month following stent implantation has allowed a very significant reduction in acute (within 24 hours) and subacute (within 30 days) coronary occlusions. Currently the aspirin-clopidogrel combination tends to be used instead of the aspirin-ticlopidine combination due to the lower hematological risk for a similar effect. GPIIBIIIA INHIBITORS: Injectable GPIIbIIIa inhibitors have changed management of the acute phase of coronary artery disease. Among these compounds, abciximab has the most extensively proven efficacy. It is mainly indicated for severe forms of coronary angioplasty with or without stent insertion. It provides a significant short-term and long-term reduction in severe events (myocardial infarction + death + revascularization). Oral formulations of GPIIbIIIa can be used to maintain and/or amplify the benefits obtained with injectable formulations. They are not currently available on the market. ASPIRIN: Due to its very low cost and low side-effect profile, aspirin plays an essential role in most indications where it remains the most widely used first-line platelet anti aggregate.

Aspirin↗
PubMed2000

Affinity purification of heparin-dependent antibodies to platelet factor 4 developed in heparin-induced thrombocytopenia: biological characteristics and effects on platelet activation.

Antibodies to heparin platelet factor 4 (H-PF4) complexes were purified from the plasma of three patients with heparin-induced thrombocytopenia (HIT) using affinity chromatography. From each plasma, the largest amount of antibodies was eluted with 2 M NaCl at pH 7.5 (peak 1) and the remainder was obtained using 0.1 M glycine/0. 5 M NaCl at pH 2.5 (peak 2). In an enzyme-linked immunosorbent assay (ELISA), we then showed that each patient had developed antibodies to PF4 displaying different characteristics. In patient 1, peak 1 IgG reacted almost exclusively with H-PF4 complexes, whereas peak 2 IgG had similar reactivity with PF4 whether or not heparin was present. Patient 2 expressed a mixture of IgA, IgM and IgG and both fractions bound to PF4 alone or to H-PF4 complexes. Finally, IgG in patient 3 only bound to H-PF4 and was unreactive with PF4 alone. Using [14C]-serotonin release assays, the antibodies developed in the three patients and exhibiting the strongest ability to activate platelets with heparin were those having the highest affinity to H-PF4. These results strongly support the hypothesis that HIT antibodies to PF4 are heterogeneous regarding their affinity and specificity for target antigens and this may greatly influence their ability to activate platelets and their pathogenicity.

Anticoagulants↗
PubMed2000

Development of an ex vivo model of pig kidney perfused with human lymphocytes. Analysis of xenogeneic cellular reactions.

BACKGROUND: Because of the explosive nature and the extremely rapid process of hyperacute rejection (HAR), significant infiltration of the xenograft by immunocompetent cells is not observed, and the role and the mechanism of action of cell-mediated rejection in discordant xenografts are therefore still under discussion. METHOD: We developed an experimental approach using pig kidneys perfused with human peripheral blood lymphocytes (PBL) in which the immunologic barrier of hyperacute rejection was excluded and which mimics the in vivo situation. RESULTS: PBL retention in the kidney was evaluated at 20-minute intervals for 3 hours. Retention increased from 30% to 80% with the time of perfusion and was specific because significantly fewer syngeneic lymphocytes were retained. Phenotype analysis of recovered PBL showed a significant decrease in natural killer (NK) cells. Immunohistochemical studies revealed the presence of NK cells and T lymphocytes in the glomerular and interstitial tubular structures of the kidney. Functional studies showed a progressive cessation of diuresis and augmentation of renal vascular resistance when the kidney was perfused with PBL. Electron microscopy examinations of kidney sections perfused with PBL showed swollen endothelial zones, suggesting alterations to and damage of the endothelium. CONCLUSIONS: This system provides a valuable model for the study of early discordant xenogeneic cellular rejection and demonstrates the predominance of xenograft infiltration by NK cells.

Animals↗