Pro-inflammatory cytokines in acute coronary syndromes: from bench to bedside.

Cytokines are produced in a variety of tissues and regulate the expression of a number of inflammatory molecules, leading to destabilization and finally rupture of vulnerable atheromatic plaques. They also participate in the pathophysiology of acute coronary syndromes (ACS) by direct effects on myocardial contractility and apoptosis. At a clinical level, circulating cytokines have a prognostic role since they are useful markers predicting future coronary events in patients with advanced atherosclerosis and in patients after ACS

Genetic polymorphism A1675G of the angiotensin type 2 receptor and its role in hypertension

The angiotensin type 2 receptor (AT2R) plays a crucial role in the regulation of blood pressure and atherogenesis. The AT2R gene is located on chromosome X and the biological effect of polymorphism A1675G in this gene still needs to be further specified. This is a review of all the studies examining the role of A1675G in arterial hypertension and cardiac disease. © Athens Medical Society

Levosimendan: a novel agent in heart failure.

Heart failure is characterised by decreased cardiac output, which results in the development of both peripheral hypoperfusion and pulmonary congestion and can lead to the development of acute pulmonary edema. The primary objective in treating a patient with decompensated heart failure is hemodynamic stabilization, which is usually achieved by inotropic support. Classic inotropic agents provide short-term hemodynamic improvement, but their use has been correlated with poor prognosis. Levosimendan, a new calcium sensitizer, offers hemodynamic and symptomatic improvement without increasing cAMP and intracellular calcium concentrations. This agent improves contractility without increasing the risk of cardiac events such as arrhythmias. By combining a positive inotropic action mediated via calcium sensitization and a vasodilatory effect via ATP-dependent potassium channels, it appears to be superior than classic positive inotropic agents. Furthermore, it seems to have prolonged benefit in heart failure patients, and it also has anti-inflammatory and antiapoptotic properties. In conclusion, levosimendan seems to be a particularly promising agent for the treatment of decompensated heart failure, as in addition to improving cardiac output, it has a more favorable side-effect profile than classic inotropic agents, and it affects multiple pathways with key role in the pathophysiology of heart failure

Levosimendan: beyond its simple inotropic effect in heart failure.

Classic inotropic agents provide short-term haemodynamic improvement in patients with heart failure, but their use has been associated with poor prognosis. A new category of inotropic agents, the Ca(2+) sensitizers, may provide an alternative longer lasting solution. Levosimendan is a relatively new Ca(2+) sensitizer which offers haemodynamic and symptomatic improvement by combining a positive inotropic action via Ca(2+) sensitization and a vasodilatory effect via adenosine triphosphate(ATP)-sensitive K(+) (K(ATP)), Ca(2+)-activated K(+) (K(Ca)(2+)) and voltage-dependent K(+) (K(V)) channels activation. Levosimendan also seems to induce a prolonged haemodynamic improvement in patients with heart failure as a result of the long half-life of its active metabolite, OR-1896. Furthermore, there is also evidence that levosimendan may have additional antiinflammatory and antiapoptotic properties, affecting important pathways in the pathophysiology of heart failure. Despite the initial reports for a clear benefit of levosimendan on short- and long-term mortality in patients with severe heart failure, the results from the recent clinical trials are rather disappointing, and it is still unclear whether it is superior to dobutamine in affecting survival of patients with severe heart failure. In conclusion, levosimendan is a promising agent for the treatment of decompensated heart failure. As further to its positive inotropic effect, it affects multiple pathways with key roles in the pathophysiology of heart failure. The results of the ongoing trials examining the effect of levosimendan on mortality in patients with heart failure will hopefully resolve the controversy as to whether levosimendan is superior to classic inotropic agents for the treatment of severe heart failure

Novel therapies targeting vascular endothelium.

Endothelial dysfunction has been identified as a major mechanism involved in all the stages of atherogenesis. Evaluation of endothelial function seems to have a predictive role in humans, and therapeutic interventions improving nitric oxide bioavailability in the vasculature may improve the long-term outcome in healthy individuals, high-risk subjects, or patients with advanced atherosclerosis. Several therapeutic strategies are now available, targeting both the synthesis and oxidative inactivation of nitric oxide (NO) in human vasculature. Statins seem to be currently the most powerful category of these agents, improving endothelial function and decreasing cardiovascular risk after long-term administration. Other cardiovascular agents improving endothelial function in humans are angiotensin-converting enzyme inhibitors/angiotensin receptors blockers, which increase NO bioavailability by modifying the rennin-angiotensin-aldosterone system. Newer therapeutic approaches targeting endothelial dysfunction in specific disease states include insulin sensitizers, L-arginine (the substrate for endothelial NO synthase [eNOS]) as well as substances that target eNOS "coupling," such as folates or tetrahydrobiopterin. Although there are a variety of strategies to improve NO bioavailability in human endothelium, it is still unclear whether they have any direct benefit at a clinical level

Novel therapies targeting vascular endothelium.

Endothelial dysfunction has been identified as a major mechanism involved in all the stages of atherogenesis. Evaluation of endothelial function seems to have a predictive role in humans, and therapeutic interventions improving nitric oxide bioavailability in the vasculature may improve the long-term outcome in healthy individuals, high-risk subjects, or patients with advanced atherosclerosis. Several therapeutic strategies are now available, targeting both the synthesis and oxidative inactivation of nitric oxide (NO) in human vasculature. Statins seem to be currently the most powerful category of these agents, improving endothelial function and decreasing cardiovascular risk after long-term administration. Other cardiovascular agents improving endothelial function in humans are angiotensin-converting enzyme inhibitors/angiotensin receptors blockers, which increase NO bioavailability by modifying the rennin-angiotensin-aldosterone system. Newer therapeutic approaches targeting endothelial dysfunction in specific disease states include insulin sensitizers, L-arginine (the substrate for endothelial NO synthase [eNOS]) as well as substances that target eNOS "coupling," such as folates or tetrahydrobiopterin. Although there are a variety of strategies to improve NO bioavailability in human endothelium, it is still unclear whether they have any direct benefit at a clinical level

Structural and functional evidence for two separate oligosaccharide binding sites of Pasteurellamultocida hyaluronan synthase

Pasteurella multocida hyaluronan synthase (PmHAS) is a bi-functional glycosyltransferase, containing a ß1,3-glucuronyltransferase and ß1,4-N-acetylglucosaminetransferase domain. PmHAS catalyzes the elongation of hyaluronan (HA) through the sequential addition of single monosaccharides to the non-reducing end of the hyaluronan chain. Research is focused on the relation between the length of the HA oligo- saccharide and the single-step elongation ki- netics from HA4 up to HA9. It was found that the turnover number kcat increased with length to maximum values of 11 and 14 s-1 for NAc- and UA-transfer, respectively. Interestingly, the spe- cificity constant kcat/KM increased with polymer length from HA5 to HA7 to a value of 44 mM-1·s-1, indicating an oligosaccharide binding site with increasing specificity towards a heptasaccha- ride at the UA domain. The value of kcat/KM re- mained moderately constant around 8 mM-1·s-1 for HA4, HA6, and HA8, indicating a binding site with significantly lower binding specificity at the NAc domain than at the UA domain. These find- ings are further corroborated by a structural homology model of PmHAS, revealing two dis- tinct sites for binding of oligosaccharides of different sizes, one in each transferase domain. Structural alignment studies between PmHAS and glycosyltransferases of the GT-A fold showed significant similarity in the binding of the UDP-sugars and the orientation of the ac- ceptor substrate. These similarities in substrate orientation in the active site and in essential amino acid residues involved in substrate bind- ing were utilized to localize the two HA oligo- saccharide binding sites