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BACKGROUND AND OBJECTIVE: We prospectively investigated combinations of risk stratifiers including multiple EP diagnostics in a cohort study of ICD patients. METHODS: For 672 enrolled patients, we collected history, LVEF, EP study and T-wave alternans testing, 24-h Holter, NT-proBNP, and the eGFR. All-cause mortality and first appropriate ICD shock were predefined endpoints. RESULTS: The 635 patients included in the final analyses were 63 ± 13 years old, 81% were male, LVEF averaged 40 ± 14%, 20% were inducible at EP study, 63% had a primary prophylactic ICD. During follow-up over 4.3 ± 1.5 years, 108 patients died (4.0% per year), and appropriate shock therapy occurred in n = 96 (3.9% per year). In multivariate regression, age (p

An important aspect of the Comprehensive In Vitro Proarrhythmia Assay (CiPA) proposal is the use of human stem cell-derived cardiomyocytes and the confirmation of their predictive power in drug safety assays. The benefits of this cell source are clear; drugs can be tested in vitro on human cardiomyocytes, with patient-specific genotypes if needed, and differentiation efficiencies are generally excellent, resulting in a virtually limitless supply of cardiomyocytes. There are, however, several challenges that will have to be surmounted before successful establishment of hSC-CMs as an all-round predictive model for drug safety assays. An important factor is the relative electrophysiological immaturity of hSC-CMs, which limits arrhythmic responses to unsafe drugs that are pro-arrhythmic in humans. Potentially, immaturity may be improved functionally by creation of hybrid models, in which the dynamic clamp technique joins simulations of lacking cardiac ion channels (e.g., IK1) with hSC-CMs in real-time during patch clamp experiments. This approach has been used successfully in manual patch clamp experiments, but throughput is low. In this study, we combined dynamic clamp with automated patch clamp of iPSC-CMs in current clamp mode, and demonstrate that IK1 conductance can be added to iPSC-CMs on an automated patch clamp platform, resulting in an improved electrophysiological maturity.

Current inotropic agents in heart failure therapy associate with low benefit and significant adverse effects, including ventricular arrhythmias. Istaroxime, a novel Na+/K+-transporting ATPase inhibitor, also stimulates SERCA2a activity, which would confer improved inotropic and lusitropic properties with less proarrhythmic effects. We investigated hemodynamic, electrophysiological and potential proarrhythmic and antiarrhythmic effects of istaroxime in control and chronic atrioventricular block (CAVB) dogs sensitive to drug-induced Torsades de Pointes arrhythmias (TdP). In isolated normal canine ventricular cardiomyocytes, istaroxime (0.3-10 μM) evoked no afterdepolarizations and significantly shortened action potential duration (APD) at 3 and 10 μM. Istaroxime at 3 μg/kg/min significantly increased left ventricular (LV) contractility (dP/dt+) and relaxation (dP/dt-) respectively by 81 and 94% in anesthetized control dogs (n = 6) and by 61 and 49% in anesthetized CAVB dogs (n = 7) sensitive to dofetilide-induced TdP. While istaroxime induced no ventricular arrhythmias in control conditions, only single ectopic beats occurred in 2/7 CAVB dogs, which were preceded by increase of short-term variability of repolarization (STV) and T wave alternans in LV unipolar electrograms. Istaroxime pre-treatment (3 μg/kg/min for 60 min) did not alleviate dofetilide-induced increase in repolarization and STV, and mildly reduced incidence of TdP from 6/6 to 4/6 CAVB dogs. In six CAVB dogs with dofetilide-induced TdP, administration of istaroxime (90 μg/kg/5 min) suppressed arrhythmic episodes in two animals. Taken together, inotropic and lusitropic properties of istaroxime in CAVB dogs were devoid of significant proarrhythmic effects in sensitive CAVB dogs, and istaroxime provides a moderate antiarrhythmic efficacy in prevention and suppression of dofetilide-induced TdP.

As the world of work is undergoing the substantial transformation known as ‘Work 4.0’, this paper explores and develops possible avenues for a corresponding transformation of labour law. It begins by identifying the underlying transformational trends (Section 1-2) to argue five core priorities for the near future of labour law: activation 2.0, transversal career management, sustained labour quality focus, continuous and integrated talent development, and active support of economic participation (Section 3). Adopting a long term view, it describes the potential dismantling of the employment contract to develop a future of labour law as a ‘law on persons’ beyond employment status, with a corresponding need to reconfigure collective consultation and bargaining (Section 4). It concludes by stressing and illustrating how the future of labour law is a choice (Section 5).

Objectives This study investigated the arrhythmogenic mechanisms responsible for torsade de pointes (TdP) in the chronic atrioventricular block dog model, known for its high susceptibility for TdP. Background The mechanism of TdP arrhythmias has been under debate for many years. Focal activity as well as re-entry have both been mentioned in the initiation and the perpetuation of TdP. Methods In 5 TdP-sensitive chronic atrioventricular block dogs, 56 needle electrodes were evenly distributed transmurally to record 240 unipolar local electrograms simultaneously. Nonterminating (NT) episodes were defibrillated after 10 s. Software was developed to automatically detect activation times and to create 3-dimensional visualizations of the arrhythmia. For each episode of ectopic activity (ranging from 2 beats to NT episodes), a novel methodology was created to construct directed graphs of the wave propagation and detect re-entry loops by using an iterative depth-first-search algorithm. Results Depending on the TdP definition (number of consecutive ectopic beats), we analyzed 29 to 54 TdP: 29 were longer than 5 beats. In the total group, 9 were NT and 45 were self-terminating. Initiation and termination were always based on focal activity. Re-entry becomes more important in the longer-lasting episodes (>14 beats), whereas in all NT TdP, re-entry was the last active mechanism. During re-entry, excitation fronts were constantly present in the heart, while during focal TdP, there was always a silent interval between 2 consecutive waves (142 ms) during which excitation fronts were absent. Interbeat intervals were significantly smaller for re-entry episodes—220 versus 310 ms in focal. Electrograms recorded in particular areas during NT TdP episodes had significantly smaller amplitude (0.38) than during focal episodes (0.59). Conclusions TdP can be driven by focal activity as well as by re-entry depending on the duration of the episode. NT episodes are always maintained by re-entry, which can be identified in local unipolar electrograms by shorter interbeat intervals and smaller deflection amplitude.

Circadian rhythms are biorhythms with a 24-hour period that are regulated by molecular clocks. Several clinical and animal models have been developed to analyze the role of these rhythms in cardiovascular physiology, disease and therapy, but a convenient in vitro model that mimics both molecular and functional circadian effects of the heart is not available. Therefore, we established a neonatal rat cardiomyocyte model that recapitulates in vivo circadian rhythmicity, as measured by anti-phasic oscillatory mRNA expression of two core clock genes, Bmal1 and Per2 and that shows functional dependence on the clock as indicated by an oscillating response in apoptosis induced by doxorubicin, hydroperoxide or hypoxia. In addition, perturbation of the cardiac clock by the use of several compounds including Resveratrol and Ex-527 was found to result in loss of functional rhythmicity. This indicates that neonatal rat cardiomyocytes are a good model to investigate the cardiac circadian clock as well as a system that allows for fast and easy preclinical testing of the influence of compounds on circadian rhythmicity that might have crucial effects on cardiac health.

Summary Stem cell antigen 1-positive (SCA1+) cells (SPCs) have been investigated in cell-based cardiac repair and pharmacological research, although improved cardiac function after injection has been variable and the mode of action remains unclear. Circadian (24-hr) rhythms are biorhythms regulated by molecular clocks that play an important role in (patho)physiology. Here, we describe (1) the presence of a molecular circadian clock in SPCs and (2) circadian rhythmicity in SPC function. We isolated SPCs from human fetal heart and found that these cells possess a molecular clock based on typical oscillations in core clock components BMAL1 and CRY1. Functional analyses revealed that circadian rhythmicity also governs SPC proliferation, stress tolerance, and growth factor release, with large differences between peaks and troughs. We conclude that SPCs contain a circadian molecular clock that controls crucial cellular functions. Taking circadian rhythms into account may improve reproducibility and outcome of research and therapies using SPCs., Highlights • SCA1+ cells are a cell source used in pharmacology studies and cardiac repair • SCA1+ cells possess a molecular circadian (24-hr) clock • Proliferation, stress tolerance, and paracrine secretion follow a circadian pattern • Taking rhythmicity into account may improve studies using SCA1+ cells, SCA1+ cells (SPCs) have been used for pharmacological studies and cell-based cardiac repair. Van Laake and colleagues isolated human SPCs and demonstrated that these cells possess molecular circadian clocks. Functional analyses revealed circadian rhythmicity in SPC proliferation, stress tolerance, and growth factor release. Their findings could improve reproducibility, translation, and outcome of studies using SPCs and other progenitor-like cells.

Evodiae fructus is a widely used herbal drug in traditional Chinese medicine. Evodia extract was found to inhibit hERG channels. The aim of the current study was to identify hERG inhibitors in Evodia extract and to investigate their potential proarrhythmic effects. Dehydroevodiamine (DHE) and hortiamine were identified as I

The detrimental effects of myocardial infarction in humans and rodents have a 24-h rhythm. In some human cohorts however, rhythmicity was absent, while the time of maximum damage differs between cohorts. We hypothesized that the type of damage influences the 24-h rhythm in infarct size. Myocardial infarction was induced in 12-week-old C57BL/six mice at four different time-points during the day using either permanent ligation (PL) or 30-min of ischemia followed by reperfusion (IR), with a control group wherein no ligation was applied. Infarct size was measured by echocardiography and histology at a 1-month follow-up. Rhythmicity in infarct size was present in the PL group at the functional and histological level, with maximal damage occurring when the infarct was induced at noon. In the IR group, no circadian rhythm was found. The time of the coronary artery ligation determines the outcome of myocardial infarction. Our data showed that in rodents, the presence of circadian rhythmicity and time of peak infarct size varies between experimental setups.

An important aspect of the Comprehensive In Vitro Proarrhythmia Assay (CiPA) proposal is the use of human stem cell-derived cardiomyocytes and the confirmation of their predictive power in drug safety assays. The benefits of this cell source are clear; drugs can be tested in vitro on human cardiomyocytes, with patient-specific genotypes if needed, and differentiation efficiencies are generally excellent, resulting in a virtually limitless supply of cardiomyocytes. There are, however, several challenges that will have to be surmounted before successful establishment of hSC-CMs as an all-round predictive model for drug safety assays. An important factor is the relative electrophysiological immaturity of hSC-CMs, which limits arrhythmic responses to unsafe drugs that are pro-arrhythmic in humans. Potentially, immaturity may be improved functionally by creation of hybrid models, in which the dynamic clamp technique joins simulations of lacking cardiac ion channels (e.g., IK1) with hSC-CMs in real-time during patch clamp experiments. This approach has been used successfully in manual patch clamp experiments, but throughput is low. In this study, we combined dynamic clamp with automated patch clamp of iPSC-CMs in current clamp mode, and demonstrate that IK1 conductance can be added to iPSC-CMs on an automated patch clamp platform, resulting in an improved electrophysiological maturity.

Atrial fibrillation (AF) is an important and highly prevalent arrhythmia, which is associated with significantly increased morbidity and mortality, including a four- to five-fold increased risk for stroke,1,2 a two-fold increased risk for dementia,3,4 a three-fold risk for heart failure,2 a two-fold increased risk for myocardial infarction,5,6 and a 40–90% increased risk for overall mortality.2,7 The constantly increasing number of AF patients and recognition of increased morbidity, mortality, impaired quality of life, safety issues, and side effects of rhythm control strategies with antiarrhythmic drugs, and high healthcare costs associated with AF have spurred numerous investigations to develop more effective treatments for AF and its complications.8 Although AF treatment has been studied extensively, AF prevention has received relatively little attention, while it has paramount importance in the prevention of morbidity and mortality, and complications associated with arrhythmia and its treatment. Current evidence shows a clear association between the presence of modifiable risk factors and the risk of developing AF. By implementing AF risk reduction strategies aiming at risk factors such as obesity, hypertension, diabetes, and obstructive sleep ap-noea (OSA), which are interrelated, we impact upon the escalating incidence of AF in the population and ultimately decrease the healthcare burden of associated co-morbidities of AF. To address this issue, a Task Force was convened by the European Heart Rhythm Association and the European Association of Cardiovascular Prevention and Rehabilitation, endorsed by the Heart Rhythm Society and Asia-Pacific Heart Rhythm Society, with the remit to comprehensively review the published evidence available, to publish a joint consensus document on the prevention of AF, and to provide up-to-date consensus recommendations for use in clinical practice. In this document, our aim is to summarize the current evidence on the association of each modifiable risk factor with AF and the available data on the impact of possible interventions directed at these factors in preventing or reducing the burden of AF. While the evidence on AF prevention is still emerging, the topic is not fully covered in current guidelines and some aspects are still controversial. Therefore, there is a need to provide expert recommendations for professionals participating in the care of at-risk patients and populations, with respect to addressing risk factors and lifestyle modifications. Health economic considerations Atrial fibrillation is a costly disease, both in terms of direct, and indirect costs, the former being reported by cost of illness studies as per-patient annual costs in the range of US $2000–14200 in North America and of €450–3000 in Europe.9 In individuals with AF or at risk of developing AF, any effective preventive measure, intervention on modifiable risk factors or comorbidities, as well as any effective pharmacological or non-pharmacological treatment has the aim to reduce AF occurrence, thromboembolic events and stroke, morbidity and, possibly, mortality related to this arrhythmia. Apart from the clinical endpoints, achievement of these goals has economic significance, in terms of positive impact on direct and indirect costs and favourable cost–effectiveness at mid- or long-term, in the perspective of healthcare systems.10–12 In view of the epidemiological profile of AF and progressive aging of the population,13 an impressive increase of patients at risk of AF or affected by AF,14 also in an asymptomatic stage, is expected in the next decades, inducing a growing financial burden on healthcare systems, not only in Europe and North America, but also worldwide.15,16 In consideration of this emerging epidemiological threat due to AF, it is worth considering a paradigm shift, going beyond the conventional approach of primary prevention based on treatment of AF risk factors, but, instead, considering the potential for ‘primordial’ prevention, defined as prevention of the development of risk factors predisposing to AF in the first place.17 This approach, aimed at avoiding the emergence and penetration of risk factors into the population, has been proposed in general terms for the prevention of cardiovascular diseases17 and should imply combined efforts of policymakers, regulatory and social service agencies, providers, physicians, community leaders, and consumers, in an attempt to improve social and environmental conditions, as well as individual behaviours, in the pursuit of adopting healthy lifestyle choices.16 Since a substantial proportion of incident AF events can be attributable to elevated or borderline levels of risk factors for AF,18 this approach could be an effective way to reduce the financial burden linked to AF epidemiology. In terms of individual behaviour and adoption of a ‘healthy lifestyle’, it is worth considering that availability of full healthcare coverage (through health insurance or the healthcare system) may in some cases facilitate the unwanted risk of reducing, at an individual level, the motivation to adopt all the preventive measures that are advisable, in line with the complex concept of ‘moral hazard effect’.19 Patient education and patient empowerment are the correct strategies for avoiding this undesirable effect.

Potassium inward rectifier K IR 2.1 channels contribute to the stable resting membrane potential in a variety of muscle and neuronal cell-types. Mutations in the K IR 2.1 gene KCNJ2 have been associated with human disease, such as cardiac arrhythmias and periodic paralysis. Crystal structure and homology modelling of K IR 2.1 channels combined with functional current measurements provided valuable insights in mechanisms underlying channel function. K IR 2.1 channels have been cloned and analyzed from all main vertebrate phyla, except reptilians. To address this lacuna, we set out to clone reptilian K IR 2.1 channels. Using a degenerated primer set we cloned the KCNJ2 coding regions from muscle tissue of turtle, snake, bear, quail and bream, and compared their deduced amino acid sequences with those of K IR 2.1 sequences from 26 different animal species obtained from Genbank. Furthermore, expression constructs were prepared for functional electrophysiological studies of ectopically expressed K IR 2.1 ion channels. In general, KCNJ2 gene evolution followed normal phylogenetic patterns, however turtle K IR 2.1 ion channel sequence is more homologues to avians than to snake. Alignment of all 31 K IR 2.1 sequences showed that all disease causing K IR 2.1 mutations, except V93I, V123G and N318S, are fully conserved. Homology models were built to provide structural insights into species specific amino acid substitutions. Snake K IR 2.1 channels became expressed at the plasmamembrane and produced typical barium sensitive (IC 50 ∼6 μM) inward rectifier currents.

INTRODUCTION: The methoxamine-sensitized rabbit model is widely used to screen drugs for proarrhythmic properties, especially repolarization-dependent TdP arrhythmias. With the change of anesthesia and/or sensitizing agent, conduction disturbances have been reported as well. Therefore, we compared currently available in-house anesthetics in order to preserve arrhythmia sensitivity and preclude conduction disturbances. METHODS AND RESULTS: Rabbits were randomly assigned to 3 groups: (1) 35 mg/kg ketamine + 5 mg/kg xylazine; (2) 0.5 mL/kg hypnorm + 3 mg/kg midazolam; (3) 35 mg/kg ketamine + 20 mg/kg propofol. Anesthesia was maintained by 1.5% isoflurane. Concomitant infusion of methoxamine (17 μg/kg/min for 40 minutes) and dofetilide (10 μg/kg/min for 30 minutes) was used to induce arrhythmias. Sole methoxamine infusion exclusively decreased HR in groups 1 and 3. Dofetilide lengthened repolarization, followed in time by PQ/QRS prolongation, second-degree AV block, and subsequently TdP arrhythmias. TdP was seen in 80%, 0%, and 33% of the rabbits in groups 1, 2, and 3, respectively. Decreasing the dose of dofetilide to 5 μg/kg/min in ketamine/xylazine anesthetized rabbits resulted in a drop in TdP incidence (25%) while conduction disturbances persisted. Flunarizine (n = 6) suppressed all TdP arrhythmias while conduction disturbances remained present. CONCLUSION: TdP incidence in the methoxamine-sensitized rabbit could be dramatically influenced by anesthesia, drug dose, and flunarizine, while conduction slowing remained present. Thus, conduction slowing seems to be the integral outcome in this model.

A planar electroluminescent (EL) lamp has been screen-printed directly on to woven polyester cotton fabric to create a smart fabric lamp. The EL lamp consists of six printed layers and has been produced in colours: light blue, dark blue, and orange. The printed structure has high durability whilst maintaining the flexible and breathable properties of the fabric. The printing process relies on an interface layer developed at the University of Southampton [1] to smooth the woven fabric surface where required, presenting a more homogenous surface than the underlying woven fabric for the subsequently printed functional layers.

Background and Purpose The density of the inward rectifier current (IK1) increases in atrial fibrillation (AF), shortening effective refractory period and thus promoting atrial re‐entry. The synthetic compound pentamidine analogue 6 (PA‐6) is a selective and potent IK1 inhibitor. We tested PA‐6 for anti‐AF efficacy and potential proarrhythmia, using established models in large animals. Experimental Approach PA‐6 was applied i.v. in anaesthetized goats with rapid pacing‐induced AF and anaesthetized dogs with chronic atrio‐ventricular (AV) block. Electrophysiological and pharmacological parameters were determined. Key Results PA‐6 (2.5 mg·kg−1·10 min−1) induced cardioversion to sinus rhythm (SR) in 5/6 goats and prolonged AF cycle length. AF complexity decreased significantly before cardioversion. PA‐6 accumulated in cardiac tissue with ratios between skeletal muscle : atrial muscle : ventricular muscle of approximately 1:8:21. In SR dogs, PA‐6 peak plasma levels 10 min post infusion were 5.5 ± 0.9 μM, PA‐6 did not induce significant prolongation of QTc and did not affect heart rate, PQ or QRS duration. In dogs with chronic AV block, PA‐6 did not affect QRS but lengthened QTc during the experiment, but not chronically. PA‐6 did not induce TdP arrhythmias in nine animals (0/9) in contrast to dofetilide (5/9). PA‐6 (200 nM) inhibited IK1, but not IK,ACh, in human isolated atrial cardiomyocytes. Conclusion and Implications PA‐6 restored SR in goats with persistent AF and, in dogs with chronic AV block, prolonged QT intervals, without inducing TdP arrhythmias. Our results demonstrate cardiac safety and good anti‐AF properties for PA‐6.

Drug‐induced ion channel trafficking disturbance can cause cardiac arrhythmias. The subcellular level at which drugs interfere in trafficking pathways is largely unknown. KIR2.1 inward rectifier channels, largely responsible for the cardiac inward rectifier current (IK 1), are degraded in lysosomes. Amiodarone and dronedarone are class III antiarrhythmics. Chronic use of amiodarone, and to a lesser extent dronedarone, causes serious adverse effects to several organs and tissue types, including the heart. Both drugs have been described to interfere in the late‐endosome/lysosome system. Here we defined the potential interference in KIR2.1 backward trafficking by amiodarone and dronedarone. Both drugs inhibited IK 1 in isolated rabbit ventricular cardiomyocytes at supraclinical doses only. In HK‐KWGF cells, both drugs dose‐ and time‐dependently increased KIR2.1 expression (2.0 ± 0.2‐fold with amiodarone: 10 μM, 24 hrs; 2.3 ± 0.3‐fold with dronedarone: 5 μM, 24 hrs) and late‐endosomal/lysosomal KIR2.1 accumulation. Increased KIR2.1 expression level was also observed in the presence of Nav1.5 co‐expression. Augmented KIR2.1 protein levels and intracellular accumulation were also observed in COS‐7, END‐2, MES‐1 and EPI‐7 cells. Both drugs had no effect on Kv11.1 ion channel protein expression levels. Finally, amiodarone (73.3 ± 10.3% P

Background and PurposeKv11.1 (hERG) channel blockade is an adverse effect of many drugs and lead compounds, associated with lethal cardiac arrhythmias. LUF7244 is a negative allosteric modulator/activator of Kv11.1 channels that inhibits early afterdepolarizations in vitro. We tested LUF7244 for antiarrhythmic efficacy and potential proarrhythmia in a dog model.Experimental ApproachLUF7244 was tested in vitro for (a) increasing human IKv11.1 and canine IKr and (b) decreasing dofetilide‐induced action potential lengthening and early afterdepolarizations in cardiomyocytes derived from human induced pluripotent stem cells and canine isolated ventricular cardiomyocytes. In vivo, LUF7244 was given intravenously to anaesthetized dogs in sinus rhythm or with chronic atrioventricular block.Key ResultsLUF7244 (0.5–10 μM) concentration dependently increased IKv11.1 by inhibiting inactivation. In vitro, LUF7244 (10 μM) had no effects on IKIR2.1, INav1.5, ICa‐L, and IKs, doubled IKr, shortened human and canine action potential duration by approximately 50%, and inhibited dofetilide‐induced early afterdepolarizations. LUF7244 (2.5 mg·kg−1·15 min−1) in dogs with sinus rhythm was not proarrhythmic and shortened, non‐significantly, repolarization parameters (QTc: −6.8%). In dogs with chronic atrioventricular block, LUF7244 prevented dofetilide‐induced torsades de pointes arrhythmias in 5/7 animals without normalization of the QTc. Peak LUF7244 plasma levels were 1.75 ± 0.80 during sinus rhythm and 2.34 ± 1.57 μM after chronic atrioventricular block.Conclusions and ImplicationsLUF7244 counteracted dofetilide‐induced early afterdepolarizations in vitro and torsades de pointes in vivo. Allosteric modulators/activators of Kv11.1 channels might neutralize adverse cardiac effects of existing drugs and newly developed compounds that display QTc lengthening.

The tidal characteristics of South Africa are explored in the present study by means of a calibrated and validated regional numerical model. The coastal tidal characteristics and semi-diurnal resonance of the South African coastline have yet to be accurately quantified. Model development was conducted in the numerical code Delft 3D for a two year simulation period. A horizontal model resolution of 1/16th geographical degree was employed. The results were calibrated against long-term measured water levels provided by the South African Navy Hydrographic Office. Model validation was performed for each major constituent's amplitude and phase lag at nine coastal locations around the South African coastline. Regional, two-dimensional comparisons were also made between this study's model results and those of the data assimilative TPXO 8 African regional model. The tide was characterized in terms of constituent amplitude and phase lag, Form Factor and tidal ellipse eccentricity regional by means of map plots. The model was particularly sensitive to bathymetry-related friction and model resolution. Accurate model results were obtained, providing the first identification and quantification of the semi-diurnal coastal resonance around South Africa. The phase lag associated with the shallower shelf areas is also clearly observed with Form Factor calculations confirming the semi-diurnal dominance of the South African coastline. The intermediate and shallow water friction-induced phase lag of the mixed progressive and standing tidal wave is also mapped, together with the tidal current phase lags.

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A hardware and software platform is presented enabling the design, and realisation via printing, of smart fabrics. The cultural and creative industries are an important economic area within which designers frequently utilise fabrics. Smart fabrics offer further creative opportunities to the cultural and creative industries, but designers often lack the required specialist knowledge, in electronics, software and materials, to produce smart fabrics. The software platform offers the ability to perform design, layout and visualisation of a smart fabric using a library of standard smart fabric functions (e.g. electroluminescence) so specialist expertise is not needed. Operation of the smart fabric can be simulated, and parameters can be set for smart fabric control electronics, which consists of standard circuit board modules. The software also provides driver code for the hardware platform to print the smart fabric. The hardware platform consists of a bespoke dispenser printer; functional inks are deposited via a pneumatic syringe controlled by the driver software, allowing bespoke rapid prototyped smart fabrics to be printed. Operation of the software and hardware system is demonstrated by the realisation of an interactive smart fabric consisting of electroluminescent lamps controlled by a proximity sensor. The modular electronics are used to control the smart fabric operation using embedded code generated by the software platform. For example, the blink rate of the electroluminescent lamp can be adjusted by the proximity of a hand. This control is achieved by the use of intuitive drop-down menus and input/output selections by the creative user. At present, the platform allows the design, print and implementation of smart fabrics incorporating the functions of colour change, electroluminescence, sound emission and proximity sensing. The platform can be expanded to add additional functions in the future and the printer will be compatible with new inks developed for screen and inkjet printing.

The European Union has become the battle ground for a growing conflict between labour protection in the member states and the economic rules of the internal market. This paper traces the emergence and development of that conflict through the case-law of the European Court of Justice. It structures the case-law in varying models of conflict resolution: labour is not a commodity; labour is exempted from market law; labour and market in balance; and market primacy and labour subordination. It offers a critical assessment of the foundations and internal contradictions of a case-law that is still developing and presents an alternative model for equilibrium between equal principles. The paper also addresses the increasing legal ramifications of the euro crisis. It sketches how labour market reforms that have been adopted at state level under the pressure of the crisis are increasingly the target of legal contestation from the perspective of European and international labour law principles.

Aims In excitable cells, KIR2.x ion-channel-carried inward rectifier current ( I K1) is thought to set the negative and stable resting membrane potential, and contributes to action potential repolarization. Loss- or gain-of-function mutations correlate with cardiac arrhythmias and pathological remodelling affects normal KIR2.x protein levels. No specific I K1 inhibitor is currently available for in vivo use, which severely hampers studies on the precise role of I K1 in normal cardiac physiology and pathophysiology. The diamine antiprotozoal drug pentamidine (P) acutely inhibits I K1 by plugging the cytoplasmic pore region of the channel. We aim to develop more efficient and specific I K1 inhibitors based on the P structure. Methods and results We analysed seven pentamidine analogues (PA-1 to PA-7) for I K1 blocking potency at 200 nM using inside-out patches from KIR2.1 expressing HEK-293 cells. PA-6 showed the highest potency and was tested further. PA-6 blocked KIR2.x currents of human and mouse with low IC50 values (12–15 nM). Modelling indicated that PA-6 had less electrostatic but more lipophilic interactions with the cytoplasmic channel pore than P, resulting in a higher channel affinity for PA-6 (Δ G −44.1 kJ/Mol) than for P (Δ G −31.7 kJ/Mol). The involvement of acidic amino acid residues E224 and E299 in drug-channel interaction was confirmed experimentally. PA-6 did not affect I Nav1.5, I Ca-L, I Kv4.3, I Kv11.1, and I Kv7.1/minK currents at 200 nM. PA-6 inhibited the inward (50 nM 40%; 100 nM 59%; 200 nM 77%) and outward (50 nM 40%; 100 nM 76%; 200 nM 100%) components of I K1 in isolated canine adult-ventricular cardiomyocytes (CMs). PA-6 prolonged action potential duration of CMs by 8 ( n = 9), 26 ( n = 5), and 34% ( n = 11) at 50, 100, and 200 nM, respectively. Unlike P, PA-6 had no effect on KIR2.1 channel expression at concentrations from 0.1 to 3 μM. However, PA-6 at 10 μM increased KIR2.1 expression levels. Also, PA-6 did not affect the maturation of hERG, except when applied at 10 μM. Conclusion PA-6 has higher efficiency and specificity to KIR2.x-mediated current than P, lengthens action potential duration, and does not affect channel trafficking at concentrations relevant for complete I K1 block.

Background— L-type calcium channel (LTCC) and Na + /Ca 2+ exchanger (NCX) have been implicated in repolarization-dependent arrhythmias, but also modulate calcium and contractility. Although LTCC inhibition is negative inotropic, NCX inhibition has the opposite effect. Combined block may, therefore, offer an advantage for hemodynamics and antiarrhythmic efficiency, particularly in diseased hearts. In a model of proarrhythmia, the dog with chronic atrioventricular block, we investigated whether combined inhibition of NCX and LTCC with SEA-0400 is effective against dofetilide-induced torsade de pointes arrhythmias (TdP), while maintaining calcium homeostasis and hemodynamics. Methods and Results— Left ventricular pressure (LVP) and ECG were monitored during infusion of SEA-0400 and verapamil in anesthetized dogs. Different doses were tested against dofetilide-induced TdP in chronic atrioventricular block dogs. In ventricular myocytes, effects of SEA-0400 were tested on action potentials, calcium transients, and early afterdepolarizations. In cardiomyocytes, SEA-0400 (1 μmol/L) blocked 66±3% of outward NCX, 50±2% of inward NCX, and 33±9% of LTCC current. SEA-0400 had no effect on systolic calcium, but slowed relaxation, despite action potential shortening, and increased diastolic calcium. SEA-0400 stabilized dofetilide-induced lability of repolarization and suppressed early afterdepolarizations. In vivo, SEA-0400 (0.4 and 0.8 mg/kg) had no effect on left ventricular pressure and suppressed dofetilide-induced TdPs dose dependently. Verapamil (0.3 mg/kg) also inhibited TdP, but caused a 15±8% drop of left ventricular pressure. A lower dose of verapamil without effects on left ventricular pressure (0.06 mg/kg) was not antiarrhythmic. Conclusions— In chronic atrioventricular block dogs, SEA-0400 treatment is effective against TdP. Unlike specific inhibition of LTCC, combined NCX and LTCC inhibition has no negative effects on cardiac hemodynamics.

A screen-printed electroluminescent digital watch display on fabric is presented. This work demonstrates the process of creating interactive printed smart fabrics suitable for a broad range of applications. In order to control the display, a series of tracks were printed that are 400μm wide with a pitch of 1mm; these dimensions are lower than the previously reported literature for connections to an EL lamp. An optimized design for a bus bar layer is designed, modelled and tested. The design improvement reduces the amount of the emitting area covered by an opaque conductor and is shown to have no negative impact on the function of the electroluminescent lamp. The design for the electroluminescent watch display includes 28 electroluminescent lamps on fabric forming four seven-segment displays. The display is the first demonstration of multiple EL seven-segment displays on fabric. The brightness is characterized and compared to commercially available blue electroluminescent lamps. The watch segments had similar brightness to commercially available lamps.

This consensus guideline discusses the electrocardiographic phenomenon of beat-to-beat QT interval variability (QTV) on surface electrocardiograms. The text covers measurement principles, physiological basis, and clinical value of QTV. Technical considerations include QT interval measurement and the relation between QTV and heart rate variability. Research frontiers of QTV include understanding of QTV physiology, systematic evaluation of the link between QTV and direct measures of neural activity, modelling of the QTV dependence on the variability of other physiological variables, distinction between QTV and general T wave shape variability, and assessing of the QTV utility for guiding therapy. Increased QTV appears to be a risk marker of arrhythmic and cardiovascular death. It remains to be established whether it can guide therapy alone or in combination with other risk factors. QT interval variability has a possible role in non-invasive assessment of tonic sympathetic activity.

Contains fulltext : 171528.pdf (Publisher’s version ) (Open Access) BACKGROUND: Ventricular remodeling increases the propensity of ventricular tachyarrhythmias and sudden death in patients. We studied the mechanism underlying these fatal arrhythmias, electrical and structural cardiac remodeling, as well as arrhythmogeneity during early, compensated hypertrophy in a rat model of chronic pressure overload. METHODS: Twenty-six Wistar rats were subjected to transverse aortic constriction (TAC) (n = 13) or sham operation (n = 13). Four weeks postoperative, echo- and electrocardiography was performed. Epicardial (208 or 455 sites) and transmural (30 sites) ventricular activation mapping was performed on Langendorff perfused hearts. Subsequently, hearts were processed for (immuno)histological and molecular analyses. RESULTS: TAC rats showed significant hypertrophy with preserved left ventricular (LV) function. Epicardial conduction velocity (CV) was similar, but more dispersed in TAC. Transmural CV was slowed in TAC (37.6 +/- 2.9 cm s(-1)) compared to sham (58.5 +/- 3.9 cm s(-1); P < 0.01). Sustained polymorphic ventricular tachycardias were induced from LV in 8/13 TAC and in 0/13 sham rats. During VT, electrical activation patterns showed variable sites of earliest epicardial activation and altering sites of functional conduction block. Wandering epicardial reentrant activation was sporadically observed. Collagen deposition was significantly higher in TAC compared to sham, but not different between arrhythmogenic and non-arrhythmogenic TAC animals. Connexin43 (Cx43) expression was heterogeneous with a higher prevalence of non-phosphorylated Cx43 in arrhythmogenic TAC animals. CONCLUSION: In TAC rats with compensated cardiac hypertrophy, dispersion of conduction correlated to arrhythmogenesis, an increased heterogeneity of Cx43, and a partial substitution with non-phosphorylated Cx43. These alterations may result in the increased vulnerability to polymorphic VTs.

Beat-to-beat variability in ventricular repolarization (BVR) associates with increased arrhythmic risk. Proarrhythmic remodeling in the dog with chronic AV-block (CAVB) compromises repolarization reserve and associates with increased BVR, which further increases upon dofetilide infusion and correlates with Torsade de Pointes (TdP) arrhythmias. It was hypothesized that these pro-arrhythmia-associated increases in BVR are induced by beat-to-beat variability in preload.Left ventricular monophasic action potential duration (LVMAPD) was recorded in acute (AAVB) and CAVB dogs, before and after dofetilide infusion. BVR was quantified as short-term variability of LVMAPD. The PQ-interval was controlled by pacing: either a constant or an alternating preload pattern was established, verified by PV-loop. The effect of the stretch-activated channel blocker, streptomycin, on BVR was evaluated in a second CAVB group. At alternating preload only, BVR was increased after proarrhythmic remodeling (0.45±0.14 ms AAVB vs. 2.2±1.1 ms CAVB, P0.01). At CAVB, but not at AAVB, dofetilide induced significant proarrhythmia. Preload variability augmented the dofetilide-induced BVR increase at CAVB (+1.5±0.8 ms vs. +0.9±0.9 ms, P=0.058). In the second group, the increase in baseline BVR by alternating preload (0.3±0.03 ms to 1.0±0.8 ms, P0.01) was abolished by streptomycin (0.5±0.2 ms, P0.05).In CAVB dogs, the inverse relation between BVR and repolarization reserve originates from an augmented sensitivity of ventricular repolarization to beat-to-beat preload changes. Stretch-activated channels appear to be involved in the mechanism of BVR. (Circ J 2016; 80: 1336-1345).

Here we reveal that the characterization of large-scale re-arrangements of signaling scaffolds induced by heart failure can serve as a novel concept to identify more specific therapeutic targets. In the mammalian heart, the cAMP pathway, with the cAMP-dependent protein kinase (PKA) in a central role, acts directly downstream of adrenergic receptors to mediate cardiac contractility and rhythm. Heart failure, characterized by severe alterations in adrenergic stimulation is, amongst other interventions, often treated with β-blockers. Contrasting results, however, have shown both beneficial and detrimental effects of decreased cAMP levels in failing hearts. We hypothesize that the origin of this behavior lies in the complex spatiotemporal organization of the regulatory subunit of PKA (PKA-R), which associates tightly with various A-kinase anchoring proteins (AKAPs) to specifically localize PKA's activity. Using chemical proteomics directly applied to human patient and control heart tissue we demonstrate that the association profile of PKA-R with several AKAPs is severely altered in the failing heart, for instance effecting the interaction between PKA and the novel AKAP SPHKAP was 6-fold upregulated upon failing heart conditions. Also a significant increase in captured cGMP-dependent protein kinase (PKG) and phosphodiesterase 2 (PDE2) was observed. The observed altered profiles can already explain many aspects of the aberrant cAMP-response in the failing human heart, validating that this dataset may provide a resource for several novel, more specific, treatment options. This article is part of a Special Issue entitled “Local Signaling in Myocytes”.

Background— Arrhythmogenic ventricular remodeling is hallmarked by both reduced gap junction expression and increased collagen deposition. We hypothesized that reduced connexin43 (Cx43) expression is responsible for enhanced fibrosis in the remodeled heart, resulting in an arrhythmogenic substrate. Therefore, we investigated the effect of normal or reduced Cx43 expression on the formation of fibrosis in a physiological (aging) and pathophysiological (transverse aortic constriction [TAC]) mouse model. Methods and Results— The Cx43 fl/fl and Cx43 CreER(T)/fl mice were aged 18 to 21 months or, at the age of 3 months, either TAC or sham operated and euthanized after 16 weeks. Epicardial activation mapping of the right and left ventricles was performed on Langendorff perfused hearts. Sustained ventricular arrhythmias were induced in 0 of 11 aged Cx43 fl/fl and 10 of 15 Cx43 Cre-ER(T)/fl mice ( P CreER(T)/fl compared with aged Cx43 fl/fl mice, whereas collagen deposition was significantly increased from 1.1±0.2% to 7.4±1.3%. Aged Cx43 CreER(T)/fl mice with arrhythmias had significantly higher levels of fibrosis and conduction heterogeneity than aged Cx43 CreER(T)/fl mice without arrhythmias. The TAC operation significantly increased fibrosis in control compared with sham (4.0±1.2% versus 0.4±0.06%), but this increase was significantly higher in Cx43 CreER(T)/fl mice (10.8±1.4%). Discoidin domain receptor 2 expression was unchanged, but procollagen peptide I and III expression and collagen type 1α2 mRNA levels were higher in TAC–operated Cx43HZ mice. Conclusions— Reduced cellular coupling results in more excessive collagen deposition during aging or pressure overload in mice due to enhanced fibroblast activity, leading to increased conduction in homogeneity and proarrhythmia.

Rationale: In vivo electrophysiology and contraction can be studied very well using minimally invasive methods. Contrarily, myocardial calcium signaling cannot be studied in vivo, although it is a crucial aspect of cardiac remodeling. Objective: We aimed to establish a method that can be used to study myocardial calcium signaling in vivo. Methods and Results: We employed the optogenetic fluorescent calcium sensor GCaMP3 to record calcium transients from the left ventricular endocardium of closed chest mice (n=8, inducible, cardiomyocyte[[Unsupported Character - Codename ­]]specific GCaMP3 transgenic overexpression). Excitation of the sensor and detection of fluorescence emission was done using a thin plastic optical fiber (250 μm) that was introduced via the carotid artery into the left ventricular cavity. Combining optogenetics with fiber optics, we were able to record endocardial calcium transients with good signal to noise ratio (6.9 ± 0.2) for up to 30 minutes at physiological heart rates, without significant bleaching of fluorescence. Conclusions: Our results demonstrate that by employing optogenetics, calcium signaling can be studied in vivo in the presence of physiologically important factors such as hemodynamic load, innervation and interaction with other organs. We expect that this approach is also suitable for other optogenetic sensors, greatly expanding possibilities for in vivo studies.

Background One of the main contributors to maladaptive cardiac remodeling is fibrosis. Connective tissue growth factor (CTGF), a matricellular protein that is secreted into the cardiac extracellular matrix by both cardiomyocytes and fibroblasts, is often associated with development of fibrosis. However, recent studies have questioned the role of CTGF as a pro-fibrotic factor. Therefore, we aimed to investigate the effect of CTGF on cardiac fibrosis, and on functional, structural, and electrophysiological parameters in a mouse model of CTGF knockout (KO) and chronic pressure overload. Methods and results A new mouse model of global conditional CTGF KO induced by tamoxifen-driven deletion of CTGF, was subjected to 16 weeks of chronic pressure overload via transverse aortic constriction (TAC, control was sham surgery). CTGF KO TAC mice presented with hypertrophic hearts, and echocardiography revealed a decrease in contractility on a similar level as control TAC mice. Ex vivo epicardial mapping showed a low incidence of pacing-induced ventricular arrhythmias (2/12 in control TAC vs. 0/10 in CTGF KO TAC, n.s. ) and a tendency towards recovery of the longitudinal conduction velocity of CTGF KO TAC hearts. Picrosirius Red staining on these hearts unveiled increased fibrosis at a similar level as control TAC hearts. Furthermore, genes related to fibrogenesis were also similarly upregulated in both TAC groups. Histological analysis revealed an increase in fibronectin and vimentin protein expression, a significant reduction in connexin43 (Cx43) protein expression, and no difference in Na V 1.5 expression of CTGF KO ventricles as compared with sham treated animals. Conclusion Conditional CTGF inhibition failed to prevent TAC-induced cardiac fibrosis and hypertrophy. Additionally, no large differences were found in other parameters between CTGF KO and control TAC mice. With no profound effect of CTGF on fibrosis formation, other factors or pathways are likely responsible for fibrosis development.

Introduction A number of predisposing factors have been suggested to be contributing to drug-induced torsade de pointes (TdP) arrhythmias: short–long–short (SLS) sequence, bradycardia, timing of drug administration, anaesthesia, ventricular remodelling, and altered ventricular activation due to ventricular ectopic beats (SLS) or idioventricular rhythm (IVR). Chronic atrio-ventricular (AV)-block (CAVB) dogs are susceptible to dofetilide-induced TdP. Methods and results In 32 anaesthetized animals, the relevance of ventricular remodelling for TdP susceptibility was studied by dofetilide [0.025 mg/kg/5 min intravenously (iv)] during bradycardia in the presence (CAVB, n = 18) or absence [acute atrio-ventricular block (AVB), n = 32] of ventricular remodelling. In sub-protocols, the possible pro-arrhythmic effects of timing of dofetilide administration: prior to ( n = 11), or after creation of AVB ( n = 9) and relevance of SLS pacing ( n = 17) was investigated during IVR. Dofetilide was also given after AVB when the activation of the ventricles was normal: pacing (1000 ms) from the high septum ( n = 7) or abnormal but fixed from the left ventricular apex ( n = 5). Torsade de pointes inducibility was defined as reproducible (≥3 times) occurrence. In acute AV block (AAVB), dofetilide did not induce TdP spontaneously (0 of 32), whereas TdP was seen in 10 out of 18 serially tested dogs in CAVB ( P < 0.001). The other factors: timing of dofetilide (0 of 11 vs. 0 of 9), SLS pacing (0 of 17 vs. 1 of 17), or ventricular activation (0 of 7 vs. 0 of 5) did not increase TdP susceptibility. Beat-to-beat variability of repolarization increased after ventricular remodelling and was highest prior to TdP induction. Conclusion In AAVB dogs, TdP is not spontaneously seen, whereas it is present in CAVB. This implies that ventricular remodelling is a prerequisite for TdP induction in this model.

Na(v)1.5, the pore forming α-subunit of the voltage-dependent cardiac Na(+) channel, is an integral membrane protein involved in the initiation and conduction of action potentials. Mutations in the gene-encoding Na(v)1.5, SCN5A, have been associated with a variety of arrhythmic disorders, including long QT, Brugada, and sick sinus syndromes as well as progressive cardiac conduction defect and atrial standstill. Moreover, alterations in the Na(v)1.5 expression level and/or sodium current density have been frequently noticed in acquired cardiac disorders, such as heart failure. The molecular mechanisms underlying these alterations are poorly understood, but are considered essential for conception of arrhythmogenesis and the development of therapeutic strategies for prevention or treatment of arrhythmias. The unravelling of such mechanisms requires critical molecular insight into the biology of Na(v)1.5 expression and function. Therefore, the aim of this review is to provide an up-to-date account of molecular determinants of normal Na(v)1.5 expression and function. The parts of the Na(v)1.5 life cycle that are discussed include (i) regulatory aspects of the SCN5A gene and transcript structure, (ii) the nature, molecular determinants, and functional consequences of Na(v)1.5 post-translational modifications, and (iii) the role of Na(v)1.5 interacting proteins in cellular trafficking. The reviewed studies have provided valuable information on how the Na(v)1.5 expression level, localization, and biophysical properties are regulated, but also revealed that our understanding of the underlying mechanisms is still limited.

Repolarization variability is considered to predict sudden cardiac death. T-wave alternans (TWA) has been the subject of exhaustive research, whereas beat-to-beat variability of repolarization (BVR) is a new parameter that possibly predicts proarrhythmia. How these parameters interact has not been tested.The purpose of this study was to compare TWA and BVR as predictors of proarrhythmic substrate early after myocardial infarction (MI).In nine pigs, MI was induced by 1-hour occlusion of the left anterior descending coronary artery. Cardiac magnetic resonance imaging was performed at day 21. Six sham pigs served as control. Spectral TWA was tested during right atrial pacing before induction of MI and after 21 days. BVR was calculated from 60 consecutive QT intervals.Magnetic resonance imaging showed transmural MI. TWA was negative in all pigs at clinical threshold rate and equally present in MI versus sham pigs at higher rates (170 bpm: 55% vs 50% positive TWA). In MI pigs, BVR of QT intervals increased significantly during acute ischemia (2.44 ± 0.43 ms vs 3.55 ± 0.41 ms, P.01) and even more on day 21 (5.80 ± 1.12 ms), but it differed significantly from sham (2.14 ± 0.54 ms, P.01). A clinical ventricular tachycardia induction protocol was positive in 2 of 8 MI pigs and in none of 6 shams.In early remodeling after MI, BVR at intrinsic heart rate was a consistent phenomenon, whereas TWA during atrial pacing or baseline QT-interval changes were not. TWA and BVR could reflect different post-MI remodeling processes. BVR may be a new technique for predicting a potentially proarrhythmic substrate in the early postinfarction period.

High-Rate Pacing Prevents Drug-Induced Arrhythmias. Introduction: High-rate pacing may have an inhibitory effect on the initiation of Torsade de Pointes arrhythmias (TdP). However, permanent pacing is only indicated in high-risk patients. We performed a proof of concept study into automatic overdrive pacing for prevention of drug-induced TdP, using short-term variability of repolarization (STV) as a feedback parameter of arrhythmic risk. Methods and Results: The minimal signal sampling frequency required for measuring STV was determined through computer simulation. Arrhythmogenic response to dofetilide (25 μg/kg/5minutes) was tested at two different paced heart rates (60–65 bpm vs 100–110 bpm) in 7 dogs with chronic atrioventricular block, while recording right and left ventricular (LV) monophasic action potential (MAP) and LV electrogram (EGM). Simulations showed a sampling frequency of 500 Hz is sufficient to capture relevant STV values. High-rate pacing prevented dofetilide-induced TdP seen at the low rate (low: 6/7 vs high: 1/7). At the low rate, STV from LV MAP duration increased before occurrence of spontaneous, ectopic activity and TdP (1.7 ± 0.6–3.0 ± 1.8 ms, P < 0.05), but at the high-rate STV did not change significantly (0.9 ± 0.2–1.5 ± 1.4 ms, NS). Regression analysis showed a close relation between STV calculated from LV MAP and from LV EGM (R2= 0.71). Conclusions: High-rate pacing increases repolarization reserve in dogs with chronic atrioventricular block, preventing dofetilide-induced TdP. Changes in repolarization reserve are reflected in values of STV. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1384-1391, December 2010)

The sodium channel isoform Na(v)1.5 mediates sodium current, excitability, and electrical conduction in the human heart. Recent studies have indicated alternative splicing within the protein-coding portion of its gene, SCN5A, as a mechanism to generate diversity in Na(v)1.5 protein structure and function. In the present study we identified several novel SCN5A transcripts in human heart, displaying distinct 5′-untranslated regions but identical protein-coding sequences. These transcripts originated from the splicing of alternative exons 1 (designated 1A, 1B, 1C, and 1D) to the translational start codon-containing exon 2, and were preferentially expressed in the heart as compared to other tissues. Comparison of their expression level between adult and fetal heart demonstrated that exon 1C- and 1D-derived sequences were more prominent in adult than in fetal heart. Two new promoters (designated P2 and P3) for the SCN5A gene were identified and functionally characterized in myocardial- and nonmyocardial-derived cell lines. Translation of the transcript containing exon 1D-derived sequences proved to be significantly impaired in these cell lines, which could be restored by mutation of an upstream translational start codon. These results implicate the usage of alternative promoters and 5′-untranslated regions as new mechanisms in the regulation of human Na(v)1.5 expression.

BACKGROUND Drug-induced torsade de pointes (TdP) arrhythmias can readily be induced in anesthetized dogs with remodeled hearts [chronic complete atrioventricular block (CAVB) dogs]. Similar studies in conscious CAVB dogs reveal lower TdP incidences. Regulations forced us to reconsider our anesthetic regimen, which consist of pentobarbital followed by halothane (P + H). We investigated the relevance of anesthesia for this enhanced susceptibility (part 1) and compared 3 anesthetic regimens (part 2). METHODS Part 1-Ten CAVB dogs paced from the high septum at 1000 milliseconds were challenged with dofetilide (25 microg x kg(-1) x 5 min(-1)) twice: once under anesthesia and once awake. Anesthesia consisted of P + H (n = 5) and thiopental maintained by isoflurane (T + I). Part 2-In CAVB dogs (n = 6) with spontaneous idioventricular rhythm, the electrophysiological and arrhythmogenic consequences of different anesthetic regimens (P + H, T + I, and P + I) were serially compared. RESULTS Part 1-In paced dogs, dofetilide-induced TdP was higher under anesthetized than in conscious circumstances, with the more severe outcome seen after T + I as compared with P + H or control (2x): 5/5, 2/5, 0/5, and 0/5, respectively; P < 0.05. Part 2-Electrophysiologically, T accelerated idioventricular rhythm, increased QTc, and transiently induced polymorphic ventricular tachycardias in 2 of 6 dogs. This was not seen after P. At 120 minutes (end of the preparation), QTc increase was highest after T + I, intermediate with P + I, and the smallest after P + H. Dofetilide in combination with T + I induced the most severe arrhythmogenic outcome. CONCLUSIONS Thiopental anesthesia causes arrhythmias sec, whereas anesthesia in general predisposes for drug-induced TdP in the CAVB dog. In combination with dofetilide, T + I has a more arrhythmic outcome than P + I or P + H.

Background and purpose: Pentamidine is a drug used in treatment of protozoal infections. Pentamidine treatment may cause sudden cardiac death by provoking cardiac arrhythmias associated with QTc prolongation and U-wave alterations. This proarrhythmic effect was linked to inhibition of hERG trafficking, but not to acute block of ion channels contributing to the action potential. Because the U-wave has been linked to the cardiac inward rectifier current (IK1), we examined the action and mechanism of pentamidine-mediated IK1 block. Experimental approach: Patch clamp measurements of IK1 were made on cultured adult canine ventricular cardiomyocytes, KIR2.1-HEK293 cells and KIR2.x inside-out patches. Pentamidine binding to cytoplasmic amino acid residues of KIR2.1 channels was studied by molecular modelling. Key results: Pentamidine application (24 h) decreased IK1 in cultured canine cardiomyocytes and KIR2.1-HEK293 cells under whole cell clamp conditions. Pentamidine inhibited IK1 in KIR2.1-HEK293 cells 10 min after application. When applied to the cytoplasmic side under inside-out patch clamp conditions, pentamidine block of IK1 was acute (IC50= 0.17 µM). Molecular modelling predicted pentamidine-channel interactions in the cytoplasmic pore region of KIR2.1 at amino acids E224, D259 and E299. Mutation of these conserved residues to alanine reduced pentamidine block of IK1. Block was independent of the presence of spermine. KIR2.2, and KIR2.3 based IK1 was also sensitive to pentamidine blockade. Conclusions and implications: Pentamidine inhibits cardiac IK1 by interacting with three negatively charged amino acids in the cytoplasmic pore region. Our findings may provide new insights for development of specific IK1 blocking compounds.

This study investigated whether ranolazine reduces dofetilide-induced torsades de pointes (TdP) in a model of long QT syndrome with down-regulated K(+) currents due to hypertrophic remodeling in the dog with chronic atrioventricular block (cAVB).Ranolazine inhibits the late Na(+) current (I(NaL)) and is effective against arrhythmias in long QT3 syndromes despite its blocking properties of the rapid component of delayed rectifying potassium current.Ranolazine was administered to cAVB dogs before or after TdP induction with dofetilide and electrophysiological parameters were determined including beat-to-beat variability of repolarization (BVR). In single ventricular myocytes, effects of ranolazine were studied on I(NaL), action potential duration, and dofetilide-induced BVR and early afterdepolarizations.After dofetilide, ranolazine reduced the number of TdP episodes from 10 +/- 3 to 3 +/- 1 (p0.05) and partially reversed the increase of BVR with no abbreviation of the dofetilide-induced QT prolongation. Likewise, pre-treatment with ranolazine, or using lidocaine as a specific Na(+) channel blocker, attenuated TdP, but failed to prevent dofetilide-induced increases in QT, BVR, and ectopic activity. In cAVB myocytes, ranolazine suppressed dofetilide-induced early afterdepolarizations in 25% of cells at 5 micromol/l, in 75% at 10 micromol/l, and in 100% at 15 micromol/l. At 5 micromol/l, ranolazine blocked 26 +/- 3% of tetrodotoxin-sensitive I(NaL), and 49 +/- 3% at 15 micromol/l. Despite a 54% reduction of I(NaL) amplitude in cAVB compared with control cells, I(NaL) inhibition by 5 micromol/l tetrodotoxin equally shortened relative action potential duration and completely abolished dofetilide-induced early afterdepolarizations.Despite down-regulation of I(NaL) in remodeled cAVB hearts, ranolazine is antiarrhythmic against drug-induced TdP. The antiarrhythmic effects are reflected in concomitant changes of BVR.

Mutations in the cardiac ryanodine receptor Ca(2+) release channel, RyR2, underlie catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited life-threatening arrhythmia. CPVT is triggered by spontaneous RyR2-mediated sarcoplasmic reticulum (SR) Ca(2+) release in response to SR Ca(2+) overload during beta-adrenergic stimulation. However, whether elevated SR Ca(2+) content--in the absence of protein kinase A activation--affects RyR2 function and arrhythmogenesis in CPVT remains elusive.Isolated murine ventricular myocytes harbouring a human RyR2 mutation (RyR2(R4496C+/-)) associated with CPVT were investigated in the absence and presence of 1 micromol/L JTV-519 (RyR2 stabilizer) followed by 100 micromol/L ouabain intervention to increase cytosolic [Na(+)] and SR Ca(2+) load. Changes in membrane potential and intracellular [Ca(2+)] were monitored with whole-cell patch-clamping and confocal Ca(2+) imaging, respectively. At baseline, action potentials (APs), Ca(2+) transients, fractional SR Ca(2+) release, and SR Ca(2+) load were comparable in wild-type (WT) and RyR2(R4496C+/-) myocytes. Ouabain evoked significant increases in diastolic [Ca(2+)], peak systolic [Ca(2+)], fractional SR Ca(2+) release, and SR Ca(2+) content that were quantitatively similar in WT and RyR2(R4496C+/-) myocytes. Ouabain also induced arrhythmogenic events, i.e. spontaneous Ca(2+) waves, delayed afterdepolarizations and spontaneous APs, in both groups. However, the ouabain-induced increase in the frequency of arrhythmogenic events was dramatically larger in RyR2(R4496C+/-) when compared with WT myocytes. JTV-519 greatly reduced the frequency of ouabain-induced arrhythmogenic events.The elevation of SR Ca(2+) load--in the absence of beta-adrenergic stimulation--is sufficient to increase the propensity for triggered arrhythmias in RyR2(R4496C+/-) cardiomyocytes. Stabilization of RyR2 by JTV-519 effectively reduces these triggered arrhythmias.

Aims Sudden arrhythmogenic cardiac death is a major cause of mortality in patients with congestive heart failure (CHF). To investigate determinants of the increased arrhythmogenic susceptibility, we studied cardiac remodelling and arrhythmogenicity in CHF patients and in a mouse model of chronic pressure overload. Methods and results Clinical and (immuno)histological data of myocardial biopsies from CHF patients with (VT+) and without (VT−) documented ventricular arrhythmia were compared with controls. In CHF patients, ejection fraction was decreased and QRS duration was increased. Cell size and interstitial fibrosis were increased, but Connexin43 (Cx43) levels, the most abundant gap junction in ventricular myocardium, were unchanged. No differences were found between VT+ and VT− patients, except for the distribution pattern of Cx43, which was significantly more heterogeneous in VT+. Mice were subjected to transverse aortic constriction (TAC) or sham operated. At 16 weeks, cardiac function was determined by echocardiography and epicardial ventricular activation mapping was performed. Transverse aortic constriction mice had decreased fractional shortening and prolonged QRS duration. Right ventricular conduction velocity was reduced, and polymorphic VTs were induced in 44% TAC and 0% sham mice. Interstitial fibrosis was increased and Cx43 quantity was unchanged in TAC mice with and without arrhythmias. Similar to CHF patients, heterogeneous Cx43 distribution was significantly associated with arrhythmias in TAC mice and with spatial heterogeneity of impulse conduction. Conclusion Heterogeneous Cx43 expression during CHF is associated with dispersed impulse conduction and may underlie enhanced susceptibility to ventricular tachyarrhythmias.

In this study we followed a new approach to analyze molecular substructures required for hERG channel blockade. We designed and synthesized 40 analogues of dofetilide (1), a potent hERG potassium channel blocker, and established structure-activity relationships (SAR) for their interaction with this important cardiotoxicity-related off-target. Structural modifications to dofetilide were made by diversifying the substituents on the phenyl rings and the protonated nitrogen and by varying the carbon chain length. The analogues were evaluated in a radioligand binding assay and SAR data were derived with the aim to specify structural features that give rise to hERG toxicity.

This paper places the European agenda of ‘flexicurity’ in a broader context. It explains how flexicurity connects to fundamental and historical characteristics of European Union labour market organization. It shows how flexicurity and the European Employment Strategy (EES) manifest a fundamental shift from EU law to EU policy. It explores the connection between flexicurity and the European Union’s agenda vis-à-vis globalization, particularly in light of the Lisbon Strategy. A broad and critical overview is given of the European Globalization Adjustment Fund (EGAF), the EU’s own and pioneering flexicurity tool in facing the labour market challenges of globalization.

Apart from clinical symptoms the diagnosis and risk stratification in long-QT syndrome (LQTS) is usually based on the surface electrocardiogram. Studies have indicated that not only prolongation of the QT interval but also an increased short-term variability of QT interval (STV(QT)) is a marker for a decreased repolarization reserve in patients with drug-induced LQTS. The aims of this study were to determine if STV(QT) (1) is higher in patients with LQTS compared with controls, (2) if this effect is more pronounced in a high-risk LQTS population, and (3) could increase the diagnostic power of the surface electrocardiogram in identifying mutation carriers. Forty mutation carriers were compared with age- and gender-matched control subjects in the absence of beta-receptor-blocking agents. Lead II or V(5) RR and QT intervals from 30 consecutive beats were manually measured. STV(QT) was determined from Poincaré plots of QT intervals (STV(QT) = Sigma|QTn + 1 - QTn|/[30 x radical2]). Compared with controls, patients with LQTS had a prolonged QTc interval (449 +/- 41 vs 411 +/- 32 ms, p = 0.00049) and increased STV(QT) (6.4 +/- 3.2 vs 4.1 +/- 1.6 ms, p = 0.005). In patients with the highest risk of clinical events, defined as a QTc interval500 ms or symptoms before beta-blocker therapy, STV(QT) was 9 +/- 4 ms. QTc interval had a sensitivity of 43% and a specificity of 97% in identifying mutation carriers (thresholds 450 ms for men and 460 ms for women). Receiver operator characteristic analysis showed that an STV(QT) of 4.9 ms was the optimal cut-off value to predict mutation carriers. When incorporating an STV(QT)4.9 ms for those whose QTc interval was within the normal limits, sensitivity to distinguish mutation carriers increased to 83% with a specificity of 68%, so that another 15 mutation carriers could be identified. In conclusion, these are the first results in humans showing that STV(QT) is increased in congenital LQTS, this effect is increased in patients with symptoms before therapy, and, hence, STV(QT) could prove to be a useful noninvasive additive marker for diagnostic screening to bridge the gap before results of genetic testing are available.