Французский язык. Практический курс по развитию навыков устной речи

<div><p>Nitrite is recognized as a bioactive nitric oxide (NO) metabolite. We have shown that nitrite inhibits platelet activation and increases platelet cGMP levels in the presence of partially deoxygenated erythrocytes. In this study, we investigated the effect of nitrite on phosphorylation of vasodilator-stimulated phosphoprotein on residue serine 239 (P-VASP^Ser239), a marker of protein kinase G (PKG) activation, in human platelets. In platelet-rich plasma (PRP), nitrite itself had no effect on levels of P-VASP^Ser239 while DEANONOate increased P-VASP^Ser239. Deoxygenation of PRP + erythrocytes (20% hematocrit) raised baseline P-VASP^Ser239 in platelets. At 20% hematocrit, nitrite (10 μM) increased P-VASP^Ser239 in platelets about 31% at 10–20 minutes of incubation while the levels of P-VASP^Ser157, a marker of protein kinase A (PKA) activation, were not changed. Nitrite increased P-VASP^Ser239 in platelets in the presence of deoxygenated erythrocytes at 20–40% hematocrit, but the effects were slightly greater at 20% hematocrit. In conclusion, our data confirm that nitrite increases P-VASP^Ser239 in platelets in the presence of deoxygenated erythrocytes. They also further support the idea that partially deoxygenated erythrocytes may modulate platelet activity, at least in part, via the NO/sGC/PKG pathway from NO formed by reduction of circulating nitrite ions.</p></div

Deferiprone increases endothelial nitric oxide synthase phosphorylation and nitric oxide production

Iron chelation can improve endothelial function. However, effect on endothelial function of deferiprone has not been reported. We hypothesized deferiprone could promote nitric oxide (NO) production in endothelial cells. We studied effects of deferiprone on blood nitrite and blood pressure after single oral dose (25 mg/kg) in healthy subjects and hemoglobin E/β-thalassemia patients. Further, effects of deferiprone on NO production and endothelial NO synthase (eNOS) phosphorylation in primary human pulmonary artery endothelial cells (HPAEC) were investigated in vitro. Blood nitrite levels were higher in patients with deferiprone therapy than those without deferiprone (P = 0.023, n = 16 each). Deferiprone increased nitrite in plasma and whole blood of healthy subjects (P = 0.002 and 0.044) and thalassemia patients (P = 0.003 and 0.046) at time 180 min (n = 20 each). Asymptomatic reduction in diastolic blood pressure (P = 0.005) and increase in heart rate (P = 0.009) were observed in healthy subjects, but not in thalassemia patients. In HPAEC, deferiprone increased cellular nitrite and phospho-eNOS(Ser1177) (P = 0.012 and 0.035, n = 6) without alteration in total eNOS protein and mRNA. We conclude that deferiprone can induce NO production by enhancing eNOS phosphorylation in endothelial cells.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Increased P-VASP^Ser239 induced by DEANONOate but not nitrite in PRP.

<p>Representative Western blot bands of P-VASP^Ser239 and VASP expression in PRP treated with 10 μM nitrite (A) or 1 μM DEANONOate (B) and quantification of P-VASP^Ser239/VASP (C) at 37 °C for 5, 10, 15, 20, 40 and 60 minutes are shown. Data are mean ± SEM (n = 3). *<i>P</i> < 0.05 tested by Student’s t-test.</p

Comparative effects of nitrite and NO donors in deoxygenated whole blood.

<p>Quantification of P-VASP^Ser239/VASP at baseline (A) and after treatment of deoxygenated whole blood with nitrite, DEANONOate and sodium nitroprusside (B) are shown. Whole blood was deoxygenated by helium for 10 minutes. Nitrite (10 μM) was incubated in deoxygenated whole blood for 15 minutes while DEANONOate (1 μM) and sodium nitroprusside (10 μM) were incubated for 5 minutes, respectively. Data are mean ± SEM (n = 5). *<i>P</i> < 0.05 compared with PRP and tested by one-way ANOVA with Tukey’s multiple comparison. ^#<i>P</i> < 0.05 compared with control and tested by one-way ANOVA with Tukey’s multiple comparison.</p

Cysteinyl Leukotriene Receptor Antagonists Induce Apoptosis and Inhibit Proliferation of Human Glioblastoma Cells by Down-regulating B-cell Lymphoma 2 and Inducing Cell Cycle Arrest

Glioblastoma is the most aggressive type of brain cancer with the highest proliferation, invasion and migration. Montelukast and zafirlukast, two widely used leukotriene receptor antagonists (LTRAs) for asthma treatment, inhibited invasion and migration of glioblastoma cell lines. Montelukast induces apoptosis and inhibites cell proliferation of various cancer cells. Herein, apoptotic and antiproliferative effects of montelukast and zafirlukast were investigated in two glioblastoma cell lines, A172 and U-87 MG. Both LTRAs induced apoptosis and inhibited cell proliferation of glioblastoma cells in a concentration-dependent manner. Montelukast was more cytotoxic and induced higher levels of apoptosis than zafirlukast in A172 cells, but not in U-87 MG cells. Both drugs decreased expression of B-cell lymphoma 2 (Bcl-2) protein without affecting Bcl-2-associated X (Bax) levels. LTRAs also reduced the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). In contrast, zafirlukast showed a greater antiproliferative effect than montelukast and induced G0/G1 cell cycle arrest by upregulating p53 and p21 expression. These results suggested that therapeutic potential of LTRAs in glioblastoma.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Increased platelet activation and lower platelet-monocyte aggregates in COVID-19 patients with severe pneumonia.

BackgroundThe increased procoagulant platelets and platelet activation are associated with thrombosis in COVID-19. In this study, we investigated platelet activation in COVID-19 patients and their association with other disease markers.MethodsCOVID-19 patients were classified into three severity groups: no pneumonia, mild-to-moderate pneumonia, and severe pneumonia. The expression of P-selectin and activated glycoprotein (aGP) IIb/IIIa on the platelet surface and platelet-leukocyte aggregates were measured prospectively on admission days 1, 7, and 10 by flow cytometry.ResultsP-selectin expression, platelet-neutrophil, platelet-lymphocyte, and platelet-monocyte aggregates were higher in COVID-19 patients than in uninfected control individuals. In contrast, aGPIIb/IIIa expression was not different between patients and controls. Severe pneumonia patients had lower platelet-monocyte aggregates than patients without pneumonia and patients with mild-to-moderate pneumonia. Platelet-neutrophil and platelet-lymphocyte aggregates were not different among groups. There was no change in platelet-leukocyte aggregates and P-selectin expression on days 1, 7, and 10. aGPIIb/IIIa expression was not different among patient groups. Still, adenosine diphosphate (ADP)-induced aGPIIb/IIIa expression was lower in severe pneumonia than in patients without and with mild-to-moderate pneumonia. Platelet-monocyte aggregates exhibited a weak positive correlation with lymphocyte count and weak negative correlations with interleukin-6, D-dimer, lactate dehydrogenase, and nitrite.ConclusionCOVID-19 patients have higher platelet-leukocyte aggregates and P-selectin expression than controls, indicating increased platelet activation. Compared within patient groups, platelet-monocyte aggregates were lower in severe pneumonia patients

Decreased nitrite reductase activity of deoxyhemoglobin correlates with platelet activation in hemoglobin E/ß-thalassemia subjects.

Nitric oxide (NO) can be generated from nitrite by reductase activity of deoxygenated hemoglobin (deoxyHb) apparently to facilitate tissue perfusion under hypoxic condition. Although hemoglobin E (HbE) solutions have been shown to exhibit decreased rate of nitrite reduction to NO, this observation has never been reported in erythrocytes from subjects with hemoglobin E/ß-thalassemia (HbE/ß-thal). In this study, we investigated the nitrite reductase activity of deoxyHb dialysates from 58 non-splenectomized and 23 splenectomized HbE/ß-thal subjects compared to 47 age- and sex-matched normal subjects, and examined its correlation with platelet activity. Iron-nitrosyl-hemoglobin (HbNO) was measured by tri-iodide reductive chemiluminescence as a marker of NO generation. HbNO produced from the reaction of nitrite with deoxyHb dialysate from both non-splenectomized and splenectomized HbE/ß-thal subjects was lower than that of normal (AA) hemoglobin subjects. P-selectin expression, a marker of platelet activation, at baseline and in reactivity to stimulation by adenosine diphosphate (ADP), were higher in HbE/ß-thal subjects than normal subjects. HbNO formation from the reactions of nitrite and deoxyHb inversely correlated with baseline platelet P-selectin expression, HbE levels, and tricuspid regurgitant velocity (TRV). Nitrite plus deoxygenated erythrocytes from HbE/ß-thal subjects had a lower ability to inhibit ADP-induced P-selectin expression on platelets than erythrocytes from normal subjects. We conclude that deoxyHb in erythrocytes from HbE/ß-thal subjects has a decreased ability to reduce nitrite to NO, which is correlated with increased platelet activity in these individuals

Platelet inhibition by nitrite is dependent on erythrocytes and deoxygenation.

Nitrite is a nitric oxide (NO) metabolite in tissues and blood, which can be converted to NO under hypoxia to facilitate tissue perfusion. Although nitrite is known to cause vasodilation following its reduction to NO, the effect of nitrite on platelet activity remains unclear. In this study, the effect of nitrite and nitrite+erythrocytes, with and without deoxygenation, on platelet activity was investigated.Platelet aggregation was studied in platelet-rich plasma (PRP) and PRP+erythrocytes by turbidimetric and impedance aggregometry, respectively. In PRP, DEANONOate inhibited platelet aggregation induced by ADP while nitrite had no effect on platelets. In PRP+erythrocytes, the inhibitory effect of DEANONOate on platelets decreased whereas nitrite at physiologic concentration (0.1 µM) inhibited platelet aggregation and ATP release. The effect of nitrite+erythrocytes on platelets was abrogated by C-PTIO (a membrane-impermeable NO scavenger), suggesting an NO-mediated action. Furthermore, deoxygenation enhanced the effect of nitrite as observed from a decrease of P-selectin expression and increase of the cGMP levels in platelets. The ADP-induced platelet aggregation in whole blood showed inverse correlations with the nitrite levels in whole blood and erythrocytes.Nitrite alone at physiological levels has no effect on platelets in plasma. Nitrite in the presence of erythrocytes inhibits platelets through its reduction to NO, which is promoted by deoxygenation. Nitrite may have role in modulating platelet activity in the circulation, especially during hypoxia