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Angiotensin II (Ang II) signaling has been implicated in cardiac arrhythmogenesis, which involves induction of reactive oxygen species (ROS). It was shown that Ang II can activate Ca/Calmodulin kinase II (CaMKII) by oxidation via a NADPH oxidase 2 (NOX2)-dependent pathway leading to increased arrhythmic afterdepolarizations. Interestingly, cAMP-dependent protein kinase A (PKA) which regulates similar targets as CaMKII has recently been shown to be redox-sensitive as well.', 'This study aims to investigate the distinct molecular mechanisms underlying Ang II-related cardiac arrhythmias with an emphasis on the individual contribution of PKA vs. CaMKII.', 'Isolated ventricular cardiac myocytes from rats and mice were used. Ang II exposure resulted in increased NOX2-dependent ROS generation assessed by expression of redox-sensitive GFP and in myocytes loaded with ROS indicator MitoSOX. Whole cell patch clamp measurements showed that Ang II significantly increased peak Ca and Na current (ICa and INa) possibly by enhancing steady-state activation of ICa and INa. These effects were absent in myocytes lacking functional NOX2 (gp91phox(-/-)). In parallel experiments using PKA inhibitor H89, the Ang II effects on peak INa and ICa were also absent. In contrast, genetic knockout of CaMKIIδ (CaMKIIδ(-/-)) did not influence the Ang II-dependent increase in peak ICa and INa. On the other hand, Ang II enhanced INa inactivation, increased late INa and induced diastolic SR (sarcoplasmic reticulum) Ca leak (confocal Ca spark measurements) in a CaMKIIδ-, but not PKA-dependent manner. Surprisingly, only the increase in diastolic SR Ca leak was absent in gp91phox(-/-)myocytes suggesting that Ang II regulates INa inactivation in a manner dependent on CaMKII- but not on NOX2. Finally, we show that Ang II increased the propensity for cellular arrhythmias, for which PKA and CaMKII contribute, both dependent on NOX2.
Does nADPH oxidase 2 mediate angiotensin II-dependent cellular arrhythmias via PKA and CaMKII?

GM-CSF has broad clinical applicability as a potent myelopoietic stimulator. However, its function is not restricted to the myelopoietic system and several observations suggest that GM-CSF may interfere with the hemostatic balance. In order to assess whether GM-CSF has any influence on hemostasis, we evaluated some coagulative and fibrinolytic parameters in patients treated with GM-CSF following chemotherapy.', 'Fibrinolytic activity (FA), fibrinogen and D-dimer were evaluated before and after high-dose cyclophosphamide in 6 patients additionally treated with GM-CSF and in 5 control patients; moreover, tissue plasminogen activator (tPA) was assayed in those treated with GM-CSF. Comparative in vitro analysis was performed on cultured endothelial cells before and after exposure to GM-CSF.', 'Control patients showed a significant decrease in plasma FA after chemotherapy compared to basal values (FA/mm2: 15.6 +/- 2.1 at day + 2 and 20.8 +/- 19 at day + 4 vs. 103.8 +/- 64.2 at day 0; p < 0.005); conversely, no FA reduction was observed in GM-CSF-treated subjects. In this latter group a marked increase in tPA antigen was seen, consistent with enhanced FA. No significant changes in plasma D-dimer and fibrinogen values were detected in the two groups. tPA, urokinase-type plasminogen activator, PAI-1 and procoagulant activity were evaluated in vitro on cultured human endothelial cells and found to be unchanged following GM-CSF addition.
Is reduction of plasma fibrinolytic activity following high-dose cyclophosphamide neutralized in vivo by GM-CSF administration?

Treatment of rheumatoid arthritis (RA) with tumor necrosis factor (TNF)-blocking agents, including etanercept and infliximab, has resulted in reductions in the radiographic progression of RA. However, the exact mechanism by which this protection occurs has not been determined. In order to add to such knowledge, we investigated the effect of anti-TNF therapy on the expression of osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) in synovial tissue.', "The expression of OPG and RANKL in synovial biopsy specimens was evaluated by immunohistochemistry. Serial synovial biopsy specimens were obtained from 18 patients with RA, before and after treatment with etanercept (9 patients) or infliximab (9 patients). Biopsy specimens were evaluated by double-blind semiquantitative analysis and image analysis. The in vitro effect of TNF antagonists on the RANKL/OPG expression in osteoblasts and endothelial cells was evaluated by Western blotting. Statistical analysis was performed using Wilcoxon's signed rank test, followed by the Bonferroni correction for multiple comparisons of paired samples. The results of in vitro experiments were evaluated by one-way analysis of variance, with Tukey's post hoc test.", 'Treatment with both infliximab and etanercept increased the expression of OPG in synovial tissue. After 8 weeks of treatment, neither infliximab nor etanercept influenced RANKL expression. In both groups of patients, the RANKL:OPG ratio decreased following therapy. In vitro, both of the TNF antagonists mimicked the in vivo effect, inducing a decrease in the RANKL:OPG ratio in TNF-primed osteoblasts and endothelial cells.

Does anti-tumor necrosis factor therapy increase synovial osteoprotegerin expression in rheumatoid arthritis?