Discovery of Icenticaftor (QBW251), a Cystic Fibrosis Transmembrane Conductance Regulator Potentiator with Clinical Efficacy in Cystic Fibrosis and Chronic Obstructive Pulmonary Disease.

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel are established as the primary causative factor in the devastating lung disease cystic fibrosis (CF). More recently, cigarette smoke exposure has been shown to be associated with dysfunctional airway epithelial ion transport, suggesting a role for CFTR in the pathogenesis of chronic obstructive pulmonary disease (COPD). Here, the identification and characterization of a high throughput screening hit 6 as a potentiator of mutant human F508del and wild-type CFTR channels is reported. The design, synthesis, and biological evaluation of compounds 7-33 to establish structure-activity relationships of the scaffold are described, leading to the identification of clinical development compound icenticaftor (QBW251) 33, which has subsequently progressed to deliver two positive clinical proofs of concept in patients with CF and COPD and is now being further developed as a novel therapeutic approach for COPD patients.

A cross-industry collaboration to assess if acute oral toxicity (Q)SAR models are fit-for-purpose for GHS classification and labelling.

This study assesses whether currently available acute oral toxicity (AOT) in silico models, provided by the widely employed Leadscope software, are fit-for-purpose for categorization and labelling of chemicals. As part of this study, a large data set of proprietary and marketed compounds from multiple companies (pharmaceutical, plant protection products, and other chemical industries) was assembled to assess the models' performance. The absolute percentage of correct or more conservative predictions, based on a comparison of experimental and predicted GHS categories, was approximately 95%, after excluding a small percentage of inconclusive (indeterminate or out of domain) predictions. Since the frequency distribution across the experimental categories is skewed towards low toxicity chemicals, a balanced assessment was also performed. Across all compounds which could be assigned to a well-defined experimental category, the average percentage of correct or more conservative predictions was around 80%. These results indicate the potential for reliable and broad application of these models across different industrial sectors. This manuscript describes the evaluation of these models, highlights the importance of an expert review, and provides guidance on the use of AOT models to fulfill testing requirements, GHS classification/labelling, and transportation needs.

Cardiac Purkinje fibers and arrhythmias; The GK Moe Award Lecture 2015.

Purkinje fibers/cells continue to be a focus of arrhythmologists. Here we review several new ideas that have emerged in the literature and fold them into important new points. These points include the following: some proteins in Purkinje cells are specific to Purkinjes; pacemaker function in Purkinje may be similar to that of the sinus node cell; sink-source concerns about tracts/sheets of Purkinje fibers; role of Ito in arrhythmias; and genetic lesions in Purkinjes and their high impact on cardiac rhythm. Although new ideas about the remodeled Purkinje cell are not the focus of this review, one can easily imagine how Purkinjes and their function may be altered in diseased hearts.

Gene therapy for restoring heart rhythm.

Efforts to use gene therapy to create a biological pacemaker as an adjunct or replacement of electronic pacemakers have been ongoing for about 15 years. For the past decade, most of these efforts have focused on the hyperpolarization-activated cyclic nucleotide gated-(HCN) gene family of channels alone or in combination with other genes. The HCN gene family is the molecular correlate of the cardiac pacemaker current, If. It is a suitable basis for a biological pacemaker because it generates a depolarizing inward current primarily during diastole and is directly regulated by cyclic adenosine monophosphate (cAMP), thereby incorporating autonomic responsiveness. However, biological pacemakers based either on native HCN channels or on mutated HCN channels designed to optimize biophysical characteristics have failed to attain the desired basal and maximal physiological heart rates in large animals. More recent work has explored dual gene therapy approaches, combining an HCN variant with another gene to reduce outward current, increase an additional inward current, or enhance cAMP synthesis. Several of these dual gene therapy approaches have demonstrated appropriate basal and maximal heart rates with little or no reliance on a backup electronic pacemaker during the period of study. Future research, besides examining the efficacy of other gene combinations, will need to consider the additional issues of safety and persistence of the viral vectors often used to deliver these genes to a specific cardiac region.

Unintended phosphorus doping of nickel nanoparticles during synthesis with TOP: a discovery through structural analysis.

We report the discovery of unintentional phosphorus (P) doping when tri-n-octylphosphine (TOP) ligands are used in Ni nanoparticle synthesis, which is the most common method for monodisperse Ni nanoparticle synthesis. The nanoparticles appear pure face-centered cubic (fcc) Ni in X-ray diffraction despite the surprisingly high level (5 atomic %) of P. We find that the P doping follows a direct relationship with increased reaction time and temperature and that the P doping can be estimated with the degree of lattice expansion shown from a peak shift in the XRD spectrum. Through EXAFS modeling and density-functional (DFT) calculations of defect formation energies we find that the P atoms are preferentially located on the fcc lattice as substitutional dopants with oxidation state of zero. Magnetic and catalytic properties are shown to be greatly affected by this doping; DFT calculations show magnetization losses in the Ni system, as well as in Fe and Co systems. These findings are likely relevant for other metal syntheses that employ phosphine ligands.

Effect of skeletal muscle Na(+) channel delivered via a cell platform on cardiac conduction and arrhythmia induction.

BACKGROUND: In depolarized myocardial infarct epicardial border zones, the cardiac sodium channel is largely inactivated, contributing to slow conduction and reentry. We have demonstrated that adenoviral delivery of the skeletal muscle Na(+) channel (SkM1) to epicardial border zones normalizes conduction and reduces induction of ventricular tachycardia/ventricular fibrillation. We now studied the impact of canine mesenchymal stem cells (cMSCs) in delivering SkM1. METHODS AND RESULTS: cMSCs were isolated and transfected with SkM1. Coculture experiments showed cMSC/SkM1 but not cMSC alone and maintained fast conduction at depolarized potentials. We studied 3 groups in the canine 7d infarct: sham, cMSC, and cMSC/SkM1. In vivo epicardial border zones electrograms were broad and fragmented in sham, narrower in cMSCs, and narrow and unfragmented in cMSC/SkM1 (P<0.05). During programmed electrical stimulation of epicardial border zones, QRS duration in cMSC/SkM1 was shorter than in cMSC and sham (P<0.05). Programmed electrical stimulation-induced ventricular tachycardia/ventricular fibrillation was equivalent in all groups (P>0.05). CONCLUSION: cMSCs provide efficient delivery of SkM1 current. The interventions performed (cMSCs or cMSC/SkM1) were neither antiarrhythmic nor proarrhythmic. Comparing outcomes with cMSC/SkM1 and viral gene delivery highlights the criticality of the delivery platform to SkM1 antiarrhythmic efficacy.

Regenerative therapies in electrophysiology and pacing.

The prevention and treatment of cardiac arrhythmias conferring major morbidity and mortality is far from optimal, and relies heavily on devices and drugs for the partial successes that have been seen. The greatest success has been in the use of electronic pacemakers to drive the hearts of patients having high degree heart block. Recent years have seen the beginnings of attempts to use novel approaches available through gene and cell therapies to treat both brady- and tachyarrhythmias. By far the most successful approaches to date have been seen in the development of biological pacemakers. However, the far more difficult problems posed by atrial fibrillation and ventricular tachycardia are now being addressed. In the following pages we review the approaches now in progress as well as the specific methodologic demands that must be met if these therapies are to be successful.

Cardiac pacing: from biological to electronic ... to biological?

The prevention and treatment of life-threatening bradyarrhythmias have been revolutionized in the last half century by electronic pacemakers. Because this represents a palliative therapy, attempts have begun to effect a cure with the novel tools of gene and cell therapy. Over time, the strategies used have coalesced to focus on achieving a stable and autonomically responsive cardiac rhythm in a setting that ultimately would require no implanted hardware. In this report, we review the history of the disease process being treated, approaches now in progress, and the demands that must be met if biological therapies are to be successful.

Examining sympathetic nerve activity with microneurography during hypnosis: untangling the effects of central command.

Using microelectrode recordings of postganglionic sympatheticaction potentials, the authors studied the effects of hypnotic suggestion on sympathetic outflow targeted to skin during static handgrip exercise. All subjects performed sustained handgrip at 33% maximal voluntary contraction (MVC) for 2 minutes during 3 consecutive trials. Two subjects randomly assigned to a hypnosis condition received suggestions that the 2nd trial was more difficult and the last trial was less difficult than the first trial. Two subjects randomly assigned to the control condition received no hypnosis or suggestions about task difficulty. In the nonhypnosis condition, skin sympathetic nerve activity (SNA) increased by 6% from baseline during the 2nd trial and 13% from baseline during the 3rd trial. In the hypnosis condition, skin SNA increased by 25% during the 2nd trial (suggestion of increased difficulty) and returned to baseline during the 3rd condition (suggestion of decreased difficulty). Therefore, the impact of central command on skin SNA is suggested by these results.

Recreating the biological pacemaker.

In recent years, several groups have reported a variety of strategies for developing biological pacemakers whose ultimate function would be to supplement/replace electronic pacemakers. Strategies have included gene therapy using naked plasmids or viral vectors and cell therapy for which both adult human mesenchymal stem cells (hMSCs) and human embryonic stem cells have been employed. This article reviews the various approaches and summarizes our own research in which the pacemaker gene, HCN2, is administered via viral vector or in an hMSC platform to produce pacemaker function in the intact canine heart.

Inhibition of COX pathway in experimental myocardial infarction.

Release of inflammatory mediators within the ischemic myocardium has long been thought to contribute to myocardial damage and dysfunction. Myocardial infarction (MI) and congestive heart failure (CHF) were induced in rats by ligating the left coronary artery. Animals were treated with the selective cyclooxygenase-2 (COX-2) inhibitor-5,5-dimethyl-3-(3-fluorophenyl1)-4-(4-methyl-sulphonyl-2(5H)-fluranone (DFU), low-, high-dose acetyl salicylic acid (aspirin), or vehicle for 3 months. Strong immunoreactivity for COX-2 was detected in the cardiomyocytes, vascular endothelial cells, and macrophages in the infarcted myocardium. Compared to the vehicle, treatment with DFU significantly reduced left ventricular end-diastolic pressure, central venous pressure, lung wet/dry ratio and infarct size, and improved cardiac contractility (P < 0.05). In comparison, treatment with low or high doses of aspirin did not significantly impact any of these parameters. These findings demonstrate that induction of myocardial COX-2 in rats with CHF secondary to MI contributes to the cardiac injury and dysfunction associated with this disease, and that therapy aimed at inhibiting this enzymatic pathway at the onset of the disease may be beneficial in the treatment of MI and CHF.