Role of redox state in modulation of ion channel function by fatty acids and phospholipids

Managing Antiplatelet Therapy and Anticoagulants in Patients with Coronary Artery Disease and Atrial Fibrillation

Oral anticoagulation (OAC) is essential in patients with atrial fibrillation (AF). Interestingly coronary artery disease coexists in 20-30% of these patients.[1,2] Balancing the risk of bleeding and thromboembolism is very important for the management of patients on OAC, especially than when such patients require percutaneous coronary intervention (PCI). Lack of data and clear societal guidelines for peri-procedural and post-procedural management of anticoagulated patients has resulted in diverse clinical practices among clinicians, hospitals, and countries. Furthermore with expanding number of available oral antiplatelet and anticoagulant agents, the uncertainty regarding optimal combination therapy in this growing pool of the patients with overlapping clinical indications is also growing. Given the high proportion of patients with atherothrombosis and requiring OAC for conditions particularly like AF, it is important that physicians are aware of the clinical implications and management of these overlapping syndromes. In this article we discuss; this evolving dilemma of peri-procedural and post-procedural management of anticoagulated patient's, burden of the disease, available data, risk factors that could identify high risk patients and propose a well-balanced management strategy.

Diagnosis and Therapy of Atrial Fibrillation: The Past, The Present and The Future

Atrial fibrillation (AF) is the most common age-related cardiac arrhythmia. It is a progressive disease, which makes treatment difficult. The progression of AF is caused by the accumulation of damage in cardiomyocytes which makes the atria more vulnerable for AF. Especially structural remodeling and electrical remodeling, together called electropathology are sustainable in the atria and impair functional recovery to sinus rhythm after cardioversion. The exact electropathological mechanisms underlying persistence of AF are at present unknown. High resolution wavemapping studies in patients with different types of AF showed that longitudinal dissociation in conduction and epicardial breakthrough were the key elements of the substrate of longstanding persistent AF. A double layer of electrically dissociated waves propagating transmurally can explain persistence of AF (Double Layer Hypothesis) but the molecular mechanism is unknown. Derailment of proteasis -defined as the homeostasis in protein synthesis, folding, assembly, trafficking, guided by chaperones, and clearance by protein degradation systems - may play an important role in remodeling of the cardiomyocyte. As current therapies are not effective in attenuating AF progression, step-by-step analysis of this process, in order to identify potential targets for drug therapy, is essential. In addition, novel mapping approaches enabling assessment of the degree of electropathology in the individual patient are mandatory to develop patient-tailored therapies. The aims of this review are to 1) summarize current knowledge of the electrical and molecular mechanisms underlying AF 2) discuss the shortcomings of present diagnostic instruments and therapeutic options and 3) to present potential novel diagnostic tools and therapeutic targets.

Loss of proteostatic control as a substrate for atrial fibrillation: a novel target for upstream therapy by heat shock proteins

Atrial fibrillation (AF) is the most common, sustained clinical tachyarrhythmia associated with significant morbidity and mortality. AF is a persistent condition with progressive structural remodeling of the atrial cardiomyocytes due to the AF itself, resulting in cellular changes commonly observed in aging and in other heart diseases. While rhythm control by electrocardioversion or drug treatment is the treatment of choice in symptomatic AF patients, its efficacy is still limited. Current research is directed at preventing first-onset AF by limiting the development of substrates underlying AF progression and resembles mechanism-based therapy. Upstream therapy refers to the use of non-ion channel anti-arrhythmic drugs that modify the atrial substrate- or target-specific mechanisms of AF, with the ultimate aim to prevent the occurrence (primary prevention) or recurrence of the arrhythmia following (spontaneous) conversion (secondary prevention). Heat shock proteins (HSPs) are molecular chaperones and comprise a large family of proteins involved in the protection against various forms of cellular stress. Their classical function is the conservation of proteostasis via prevention of toxic protein aggregation by binding to (partially) unfolded proteins. Our recent data reveal that HSPs prevent electrical, contractile, and structural remodeling of cardiomyocytes, thus attenuating the AF substrate in cellular, Drosophila melanogaster, and animal experimental models. Furthermore, studies in humans suggest a protective role for HSPs against the progression from paroxysmal AF to persistent AF and in recurrence of AF. In this review, we discuss upregulation of the heat shock response system as a novel target for upstream therapy to prevent derailment of proteostasis and consequently progression and recurrence of AF.

Inhibitors of brain phospholipase A2 activity: their neuropharmacological effects and therapeutic importance for the treatment of neurologic disorders

The phospholipase A(2) family includes secretory phospholipase A(2), cytosolic phospholipase A(2), plasmalogen-selective phospholipase A(2), and calcium-independent phospholipase A(2). It is generally thought that the release of arachidonic acid by cytosolic phospholipase A(2) is the rate-limiting step in the generation of eicosanoids and platelet activating factor. These lipid mediators play critical roles in the initiation and modulation of inflammation and oxidative stress. Neurological disorders, such as ischemia, spinal cord injury, Alzheimer's disease, multiple sclerosis, prion diseases, and epilepsy are characterized by inflammatory reactions, oxidative stress, altered phospholipid metabolism, accumulation of lipid peroxides, and increased phospholipase A(2) activity. Increased activities of phospholipases A(2) and generation of lipid mediators may be involved in oxidative stress and neuroinflammation associated with the above neurological disorders. Several phospholipase A(2) inhibitors have been recently discovered and used for the treatment of ischemia and other neurological diseases in cell culture and animal models. At this time very little is known about in vivo neurochemical effects, mechanism of action, or toxicity of phospholipase A(2) inhibitors in human or animal models of neurological disorders. In kainic acid-mediated neurotoxicity, the activities of phospholipase A(2) isoforms and their immunoreactivities are markedly increased and phospholipase A(2) inhibitors, quinacrine and chloroquine, arachidonyl trifluoromethyl ketone, bromoenol lactone, cytidine 5-diphosphoamines, and vitamin E, not only inhibit phospholipase A(2) activity and immunoreactivity but also prevent neurodegeneration, suggesting that phospholipase A(2) is involved in the neurodegenerative process. This also suggests that phospholipase A(2) inhibitors can be used as neuroprotectants and anti-inflammatory agents against neurodegenerative processes in neurodegenerative diseases.