Cardiovascular & Haematological Disorders - Drug Targets - Volume 6, Issue 2, 2006

Aim of the study is to evaluate the effects of Prostaglandin E-1 (PGE-1) in patients with peripheral arterial disease (PAD) at the 2nd b stage Fontaine's classification. The study, controlled, single blinded, enrolled 123 patients with intermittent claudication that were randomised in two groups; the first group received a treatment with PGE-1 while the second one received a pentoxifylline-buflomedil association by venous infusion. We evaluated: Pain Free Walking Distance (PFWD), Maximum Walking Distance (MWD), Rest Flow (RF), Peak Flow (PF), Basal (BVR) and Minimal Vascular Resistance (MVR) with a strain gauge plethysmograph, Resting Flow (RF), Peak Flow (PF), time to reach the Peak Flow (tPF) and time to recovery of the base values (tRF) with laser Doppler flowmeter. After a four weeks treatment, we observed an increase of 370% about PFWD and of 260% in the MWD in patients treated with PGE-1; the other group showed an increase of 110% and 118% respectively. Moreover, the patients of the first group showed a significant increase regarding the plethysmographic Peak Flow (from 9.75±1.37 to 16.21±1.75, p<0.001), greater than the one observed in the second group (from 9.53±1.41 to 13.47±1.53, p<0.05); also the laser Doppler parameters showed a significant reduction, more evident in the first group (tPF from 23.0±7.5 to 10.5±4.9, p<0.001; tRF from 73.5±22.7 to 48.3±13.5, p<0.001) than in the second one. In conclusion, our study shows the efficacy of PGE-1 in patients with 2nd b stage Fontaine PAD; PGE-1 improves the microcirculation and the haemodynamics in peripheral districts and determines an increase in the pain free walking distance and in maximum walking distance.

Myocardial injury during coronary intervention occurs in 10-40% of cases and is often characterized by a slight increase of markers of myocardial necrosis, without symptoms, electrocardiographic changes or impairment of cardiac function. However, even small increases of creatine kinase-MB levels are expression of a true and detectable infarction, and may be associated with higher follow-up mortality. The cause of CK-MB elevation in case of procedural complications (dissection, transient vessel closure, no reflow, side branch occlusion etc.) is obvious; however, most cases of minor CK-MB elevation occur in patients with uncomplicated procedure with excellent final angiographic results. It has been suggested that the main mechanism explaining occurrence of myocardial necrosis during otherwise successful coronary interventions may be distal microembolization of plaque components, an enhanced inflammatory state or due to total plaque burden and/or to plaque instability. Different treatments have been proposed to prevent myocardial injury during coronary intervention, including nitrate infusion, intracoronary beta-blockers, adenosine, clopidogrel and IIb/IIIa inhibitors, but none of those (apart from the use of IIb/IIIa inhibitors) has been routinely introduced in clinical practice. We performed the ARMYDA (Atorvastatin for Reduction of MYocardial Damage during Angioplasty) trial, i.e. the first prospective, randomised, placebo controlled study to evaluate effects of 7 days of pre-treatment with a fixed dose of atorvastatin (40 mg/day) on post-procedural release of markers of myocardial damage in patients with stable angina undergoing percutaneous intervention. In this study therapy with atorvastatin has been associated with 80% risk reduction on the occurrence of peri-procedural myocardial infarction, as well as with significant reduction of post-intervention peak levels of all markers of myocardial damage. The mechanisms underlying the beneficial effects of atorvastatin may be an inflammatory action reducing myocardial necrosis due to microembolization, an improvement of endothelial function on microcirculation, and direct protection of myocardium.

Non-steroidal anti-inflammatory drugs (NSAIDs) represent a clinically important class of agents. NSAIDs are commonly used in treatment of conditions such as headache, fever, inflammation and joint pain. Complications often arise from chronic use of NSAIDs. Gastrointestinal (GI) toxicity in the form of gastritis, peptic erosions and ulcerations and GI bleeds limit usage of NSAIDs. These toxicities are thought to be due to cyclooxygenase (COX)-1 blockade. COX-1 generates cytoprotective prostanoids such as prostaglandin (PG) E2 and prostacyclin (PGI2). COX-2 inhibitors, commonly referred to as coxibs, were developed to inhibit inflammatory prostanoids without interfering with production of COX-1 prostanoids. Concerns over cardiovascular safety, however, have evolved based on the concept of inhibition of COX-2- derived endothelial prostanoids without inhibition of platelet thromboxane A2, leading to increased cardiovascular risk. The Celecoxib Long-Term Arthritis Safety Study (CLASS) trial did not show a significant increase in cardiovascular risk for celecoxib (Celebrex), but results of the Vioxx Gastrointestinal Outcomes Research (VIGOR) study showed an increased cardiovascular risk with long-term daily usage of rofecoxib in patients with rheumatoid arthritis. The Adenomatous Poly Prevention on Vioxx (APPROVe) trial further evaluated cardiovascular effects of rofecoxib and recently led to removal of this drug from the marketplace. Coxibs affect renal function via blockade of normal COX-2 functions. COX-2 expression increases in high renin states and in response to a high-sodium diet or water deprivation. PGI2 and PGE2 are the most important renal prostanoids. PGI2 inhibition results in hyperkalemia. PGE2 inhibition results in sodium retention, which leads to hypertension, peripheral edema and potentially exacerbation of heart failure. This review article discusses beneficial and deleterious effects associated with prostanoids produced by COX-1 and COX-2 in various organs and how blockade of these products translates into clinical medicine.

The heart originates from bilateral primordia that eventually fuse in the embryonic midline leading to a linear tube. Soon after, the heart bends to the right and atrial and ventricular chambers are formed. Progressively each embryonic compartment initiates a process of septation that eventually leads to a four chambered heart with a double circuitry and synchronous contraction. During these developmental events, the growth of the heart and in particular of its myocardial component gradually increases. However, as the heart gets into its mature stage, myocardial growth ceases and concomitantly the myocardium looses its proliferative capacity. In the adult human population, the most frequent cardiac pathologies emanate from a decompensated lost of myocardial function. Therapeutical approaches aiming to add or replace new myocytes to the failing heart are thus highly desired. Embryonic stem cells have a high capacity to give rise to multiple cell types, including myocardial cells, opening new therapeutical possibilities. Unexpectedly discrete adult cell populations have also shown a greater cell plasticity than previously thought, earning therefore much attention as therapeutic targets. These observations have launched initial clinical trials with great hope of clinical benefit. However, it is essential in this respect to initially understand, and eventually control myogenic cell fate determination. Developmental biology of the heart provides a very suitable model for this end. Over the last decade there has been a considerable advance in the understanding of the molecular mechanisms that lead to the determination of the cardiomyocyte lineage and the regulatory mechanisms by which morphogenesis of the heart takes place. Growth factor signalling and transcriptional events controlling cardiac myogenesis have been progressively unravelled. In this review we aim to summarise current data concerning the cardiomyogenic cell fate determination pathways occurring during the natural process of cardiogenesis as compared to the myogenic lineages obtained from embryonic and adult stem cells. Identification of key elements provides important resources to which drugs can be targeted and eventually can result in promising tools to control and expand cardiomyocyte determination.

Reperfusion of ischemic myocardium after acute myocardial infarction (AMI) induces a local activation of inflammatory reactions that results in ischemia/reperfusion (I/R)-injury. I/R-injury contributes considerably to the total cell damage in the heart after AMI. Secretory phospolipase A2-IIA (sPLA2-IIA), C-reactive protein (CRP) and complement are inflammatory mediators that have been demonstrated to play key roles in I/R injury. From studies by us and others a mechanism emerged in which sPLA2-IIA binds to reversibly damaged cardiomyocytes and subsequently induces cell death, partly by potentiating binding of CRP and subsequent complement activation. Next to this, sPLA2-IIA also has a direct toxic effect, independent of CRP or complement. Therefore, these studies indicate a crucial role of inflammatory mediators in ischemia/reperfusion injury. This review will focus on the pathogenic effects of sPLA2-IIA, CRP and complement and on the putative therapeutic effects of inhibitors of these inflammatory mediators in acute myocardial infarction.

Adrenomedullin (ADM) is a potent vasodilator peptide that was originally isolated from human pheochromocytoma. Its vasodilatory effect is mediated by cyclic adenosine 3',5'-monophosphate- and nitric oxidedependent mechanisms. Earlier studies have demonstrated that ADM is secreted from various tissues, including vessels, heart, and lungs. In addition, there are specific receptors for ADM in the lungs. Plasma ADM level is elevated in proportion to the severity of pulmonary hypertension, and circulating ADM is partially metabolized in the lungs. These findings suggest that ADM plays an important role in the regulation of pulmonary vascular tone. Administration of ADM by intravenous or intratracheal delivery significantly decreased pulmonary arterial pressure and pulmonary vascular resistance in patients with pulmonary arterial hypertension. Furthermore, we have recently developed a new therapeutic strategy using ADM gene-modified endothelial progenitor cells (EPC). Intravenously administered ADM gene-modified EPC were incorporated into lung tissues and attenuated monocrotaline-induced pulmonary hypertension in rats. In addition, ADM has angiogenic and anti-apoptotic activities via activation of Akt and/or mitogen-activated protein kinase. These findings suggest that ADM may act not only as a vasodilator but also as a vasoprotective factor. Thus, ADM may be a promising endogenous peptide for the treatment of pulmonary hypertension.

The uraemic syndrome is a complex condition that results from an accumulation of multiple waste compounds, combined with failure of the endocrine and homeostatic functions of the kidney in end-stage chronic renal failure (CRF) patients. Recently it has become clear that uraemia is a microinflammatory condition with a significant increase in inflammation markers. Malnutrition is a common pathological condition which exacerbates cardiovascular mortality in uraemic patients. Inadequate diet and a state of persistent catabolism play major roles in uraemic malnutrition, yet the underlying mechanisms have not been completely clarified. Malnourished patients present elevated levels of circulating cytokines, further aggravating the oxidative and inflammatory characteristics of uraemia. It has been suggested that abnormalities in nitric oxide bioactivity, coupled with malnutrition and inflammation, may contribute to increased incidence of atherothrombotic events in uraemia. Amongst the earliest indications of nutritional deficiency are low concentrations of plasma amino acids, including L-arginine, the precursor for nitric oxide (NO) synthesis. Atherosclerosis is an inflammatory disorder and NO is an important mediator of inflammation. There is a close association between thrombosis and platelet aggregation, and NO is involved in all stages of platelet activation. L-arginine inhibits platelet aggregation both in vitro and in vivo, while L-NMMA (NG-monomethyl-L-arginine), an endogenous L-arginine analogue and inhibitor of NO synthase (NOS), increases platelet activation and adhesion. The majority of studies in animal models and human patients indicate that the systemic production of NO is increased in uraemia. CRF patients show reduced plasma concentration of L-arginine, and the enhancement of L-arginine transport is essential to maintain increased NO synthesis in platelets taken from these patients. The present review provides an overview of recent advances in the understanding of the association among malnutrition, chronic inflammation and the L-arginine-nitric oxide pathway in uraemic patients, and related potential interventions that could improve clinical outcome in chronic renal failure.