Measuring oxidative burden and predicting pharmacological response in coronary artery disease patients with a novel direct activator of haem-free/oxidised sGC.

OBJECTIVE: The soluble guanylate cyclase (sGC) activator Cinaciguat (BAY 58-2667) represents a novel class of drugs that selectively activate oxidised sGC. The extent of oxidised sGC depends on the patient's oxidative burden. We here describe two platelet-based assays that allow determining the extent of oxidised sGC and thus provide a basis for an individualised pharmacotherapy. METHODS/RESULTS: Platelets obtained from patients with (n=12) and without (n=12) coronary artery disease (CAD) were examined by flow cytometry (P-selectin expression), and Western blots (vasodilator associated phosphoprotein, VASP-phosphorylation). Results were compared to maximal oxidation of sGC achieved by the oxidising agent ODQ (1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one). Treatment of platelets with Cinaciguat resulted in differential activation of oxidised sGC. Platelet P-selectin expression and VASP-phosphorylation revealed significant differences (p=0.012, p=0.039, respectively) between CAD and non-CAD patients. CONCLUSION: We describe platelet-based assays that allow the determination of patients' oxidative status and thus allow the prediction of pharmacological response to direct sGC activators.

Selenium supplementation induces metalloproteinase-dependent L-selectin shedding from monocytes.

Selenium therapy in patients with severe sepsis improves clinical outcome and has been associated with increased activity of the selenoprotein glutathione peroxidase. However, the mechanism of the observed beneficial effects remains unclear. We determined the effect of selenium treatment on the monocyte adhesion molecule L-selectin and L-selectin-related monocyte functions in vitro and transferred our findings to an in vivo mouse model. Monocytes were purified, cultured, and incubated in the presence or absence of supplemented selenium and metalloproteinase (MP) inhibitors for up to 16 h. Expression of L-selectin was unaffected after 2 and 6 h but decreased after 16 h of incubation in the presence of selenium. Soluble L-selectin (sL-selectin) in the supernatant was determined by ELISA. A 2.3-fold increase as a result of shedding of L-selectin was observed after 16 h of selenium treatment. Addition of the MP inhibitors GM6001, TNF-alpha-converting enzyme inhibitor 2, or GW280264X strongly reduced selenium-induced L-selectin shedding, indicating a MP-dependent mechanism. The functional consequences of L-selectin shedding were examined in a flow chamber model. Selenium-treated monocytes showed significantly decreased rolling and adhesion to the L-selectin ligand Sialyl-Lewis(a) under conditions of venous shear stress (0.5 dyne/cm(2)). Selenium treatment of C57BL6 mice led to increased serum levels of sL-selectin, underscoring the in vivo relevance of our findings. We describe a selenium-induced down-regulation of L-selectin on monocytes as a consequence of MP-dependent shedding of this membrane-anchored adhesion molecule. The impairment of monocyte adhesion by selenium supplementation may represent an important, underlying mechanism for the modulation of inflammatory reactions in patients with severe sepsis.

Sinus node arrest secondary to HSV encephalitis.

We report a patient with herpes simplex virus (HSV) encephalitis presenting as recurrent syncope due to sinus node arrest. Although the patient's initial presentation suggested a primary cardiac cause, an eventual diagnosis of HSV encephalitis was supported by computed tomography scan and magnetic resonance imaging, and confirmed by HSV polymerase chain reaction. The mechanism of cardiac arrhythmias in HSV encephalitis remains unclear; however, cardiac monitoring should be considered in all patients in whom the diagnosis is suspected. With diagnosis and appropriate management, a permanent pacemaker is generally not indicated. This case report highlights the importance of considering potentially reversible causes of collapse secondary to sinus node dysfunction beyond primary cardiac causes.

Direct thrombin inhibition with bivalirudin as an antithrombotic strategy in general and interventional cardiology.

Antithrombotic therapy is a crucial component of interventional cardiology and currently involves the administration of both anticoagulant and antiplatelet agents. The implementation of standard dual or triple antiplatelet therapies has allowed percutaneous coronary intervention (PCI) with stent implantation to become the treatment of choice in most patients with acute coronary syndromes (ACS), particularly in patients with ST-segment elevation myocardial infarction. However, the combined use of antithrombotic agents increases the bleeding risk associated with coronary intervention, which is a concern due to the increasing evidence that bleeding complications are associated with a higher risk of ischaemic events and death. The shortcomings of currently available anticoagulant drugs have promoted the ongoing development of new, powerful anticoagulant agents that have both efficacy in the setting of PCI and a reduced risk of bleeding; one of these classes of agents targets the thrombin molecule, a key factor in the coagulation cascade, and belongs to the class of anticoagulants known as direct thrombin inhibitors (DTIs). Bivalirudin, a synthetic peptide, is a DTI with unique, favourable pharmacological properties that include predictable linear pharmacokinetics. Bivalirudin was approved as an anticoagulant in patients undergoing routine PCI in 2000 by the FDA (in 2004 in Europe and Australia) and more recently in patients with ACS undergoing PCI. The pharmacological properties of bivalirudin, along with current indications for its use, are discussed in this review, with a focus on the major completed and ongoing clinical trials with bivalirudin.