Long-QT syndrome (LQTS) is an arrhythmogenic disorder characterised by prolongation of the QT interval in the electrocardiogram, which can lead to sudden cardiac death. Pharmacological treatments are far from optimal for congenital forms of LQTS, while the acquired form, often triggered by drugs that (sometimes inadvertently) target the cardiac hERG channel, is still a challenge in drug development because of cardiotoxicity. Current experimental models in vitro fall short in predicting proarrhythmic properties of new drugs in humans. Here, we leveraged a series of isogenically matched, diseased and genetically engineered, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from patients to test a novel hERG allosteric modulator for treating congenital LQTS, drug-induced LQTS or a combination of the two. By slowing I Kr deactivation and positively shifting I Kr inactivation, the small molecule LUF7346 effectively rescued all of these conditions, demonstrating in a human system that allosteric modulation of hERG may be useful as an approach to treat inherited and druginduced LQTS. Furthermore, our study provides experimental support of the value of isogenic pairs of patient hiPSC-CMs as platforms for testing drug sensitivities and performing safety pharmacology.

Preclinical models of inflammatory diseases (e.g., neuropathic pain, rheumatoid arthritis, and multiple sclerosis) have pointed to a critical role of the chemokine receptor 2 (CCR2) and chemokine ligand 2 (CCL2). However, one of the biggest problems of high-affinity inhibitors of CCR2 is their lack of efficacy in clinical trials. We report a new approach for the design of high-affinity and long-residence-time CCR2 antagonists. We developed a new competition association assay for CCR2, which allows us to investigate the relation of the structure of the ligand and its receptor residence time [i.e., structure-kinetic relationship (SKR)] next to a traditional structure-affinity relationship (SAR). By applying combined knowledge of SAR and SKR, we were able to re-evaluate the hit-to-lead process of cyclopentylamines as CCR2 antagonists. Affinity-based optimization yielded compound 1 with good binding (Ki = 6.8 nM) but very short residence time (2.4 min). However, when the optimization was also based on residence time, the hit-to-lead process yielded compound 22a, a new high-affinity CCR2 antagonist (3.6 nM), with a residence time of 135 min.

BACKGROUND AND PURPOSEDrug-induced arrhythmia due to blockade of the Kv11.1 channel (also known as the hERG K + channel) is a frequent side effect. Previous studies have primarily focused on equilibrium parameters, i.e. affinity or potency, of drug candidates at the channel. The aim of this study was to determine the kinetics of the interaction with the channel for a number of known Kv11.1 blockers and to explore a possible correlation with the affinity or physicochemical properties of these compounds. EXPERIMENTAL APPROACHThe affinity and kinetic parameters of 15 prototypical Kv11.1 inhibitors were evaluated in a number of [ 3 H]-dofetilide binding assays. The lipophilicity (logKW-C8) and membrane partitioning (logKW-IAM) of these compounds were determined by means of HPLC analysis. KEY RESULTS A novel [3 H]-dofetilide competition association assay was set up and validated, which allowed us to determine the binding kinetics of the Kv11.1 blockers used in this study. Interestingly, the compounds' affinities (Ki values) were correlated to their association rates rather than dissociation rates. Overall lipophilicity or membrane partitioning of the compounds were not correlated to their affinity or rate constants for the channel.

Drug-induced blockade of the human ether-a-go-go-related gene K(+) channel (hERG) represents one of the major antitarget concerns in pharmaceutical industry. SAR studies of this ion channel have shed light on the structural requirements for hERG interaction but most importantly may reveal drug design principles to reduce hERG affinity. In the present study, a novel library of neutral and positively charged heteroaromatic derivatives of the class III antiarrhythmic agent dofetilide was synthesized and assessed for hERG affinity in radioligand binding and manual patch clamp assays. Structural modifications of the pyridine moiety, side chain, and peripheral aromatic moieties were evaluated, thereby revealing approaches for reducing hERG binding affinity. In particular, we found that the extra rigidity imposed close to the positively charged pyridine moiety can be very efficient in decreasing hERG affinity.

Metal nanostructures are of great interest because of their important applications in catalysis, [1] sensing, [2] surface-enhanced Raman scattering (SERS), [3] optoelectronics, [4] information storage, [5] and optics. [6] Further processing of these nanostructures into ordered arrays or entities with a hollow interior is technically important as it could lead to a significant improvement of their optical, catalytic, biosensing, or SERS performances. [6][7][8][9] For example, ordered metal microstructures have been demonstrated to exhibit a photonic bandgap in which the propagation of electromagnetic waves is prohibited. [7] In another example, Halas and co-workers have demonstrated that the surface plasmon resonance (SPR) of gold nanoshells can be tuned from the visible to near-infrared region of the electromagnetic spectrum.[10] For potential applications, it is highly desirable to develop new strategies to arrange hollow metal units into ordered structures and to allow control of their separation on a nanometer scale. Hollow metal nanostructures are often prepared by templating against sacrificial templates, such as colloidal microspheres, [11][12][13][14][15][16][17][18] or channels in anodized aluminum oxide and track-etched polycarbonate membranes. [19,20] A convenient method to prepare ordered metal nanomaterials is to deposit metal against colloidal crystal templates. [21][22][23] Although new strategies have been developed to fabricate isolated units of metallic hollow nanostructures, [24] there are few methods that can allow the preparation of highly monodisperse hollow metal nanostructures and their ordered arrays. [12,15,25,26] One of the successful methods is the so-called lost-wax approach demonstrated by Colvin and co-workers. [27] This method uses a silica colloidal crystal as the starting template to create a macroporous polymer membrane. Highly monodisperse and ordered inorganic, polymeric, and metallic hollow nanostructures can be generated within the uniform voids in the membranes. [27] In this communication, the preparation of a novel ordered gold network with hollow interiors by a two-step replication procedure is reported. A non-close-packed (NCP) silica colloidal crystal, first introduced by Fenollosa and Meseguer, [28] is used as the primary template. Macroporous polystyrene (PS) membranes are prepared by replication of the NCP silica opals, which contain spherical voids that are interconnected with nanochannels. Monodisperse hollow gold spheres interconnected with gold nanonecks with a hollow interior are electroless-plated within the PS membranes. More importantly, an indirect seeding method is adopted so as to confine plating mainly to the void surface of the PS template. A wide reflectance minimum band is observed in the near-infrared specular reflectivity spectra of the gold nanoshell/nanotube networks. It is believed that these highly ordered nanostructures may have applications in areas such as plasmonics, biophysics, and nanophotonics.The method to fabricate a NCP gold nanoshel...

Background— Ventricular arrhythmias as a result of unintentional blockade of the K v 11.1 (hERG [human ether-à-go-go–related gene]) channel are a major safety concern in drug development. In past years, several highly prescribed drugs have been withdrawn for their ability to cause such proarrhythmia. Here, we investigated whether the proarrhythmic risk of existing drugs could be reduced by K v 11.1 allosteric modulators. Methods and Results— Using [ 3 H]dofetilide-binding assays with membranes of human K v 11.1-expressing human embryonic kidney 293 cells, 2 existing compounds (VU0405601 and ML-T531) and a newly synthesized compound (LUF7244) were found to be negative allosteric modulators of dofetilide binding to the K v 11.1 channel, with LUF7244 showing the strongest effect at 10 μmol/L. The K v 11.1 affinities of typical blockers (ie, dofetilide, astemizole, sertindole, and cisapride) were significantly decreased by LUF7244. Treatment of confluent neonatal rat ventricular myocyte (NRVM) monolayers with astemizole or sertindole caused heterogeneous prolongation of action potential duration and a high incidence of early afterdepolarizations on 1-Hz electric point stimulation, occasionally leading to unstable, self-terminating tachyarrhythmias. Pretreatment of NRVMs with LUF7244 prevented these proarrhythmic effects. NRVM monolayers treated with LUF7244 alone displayed electrophysiological properties indistinguishable from those of untreated NRVM cultures. Prolonged exposure of NRVMs to LUF7244 or LUF7244 plus astemizole did not affect their viability, excitability, and contractility as assessed by molecular, immunological, and electrophysiological assays. Conclusions— Allosteric modulation of the K v 11.1 channel efficiently suppresses drug-induced ventricular arrhythmias in vitro by preventing potentially arrhythmogenic changes in action potential characteristics, raising the possibility to resume the clinical use of unintended K v 11.1 blockers via pharmacological combination therapy.

ObjectiveThis study was designed to evaluate the functional and radiological outcomes of patients with complex tibial plateau fractures treated with double-buttress plate fixation.MethodsSixty five cases of complex (Schatzker type V and VI) tibial plateau fractures were treated with double-buttress plate fixation in our centre from September 2001 to September 2006 through two separate plate incisions. Fifty four patients were followed up for a period ranging from 12 to 48 months and evaluated for the functional and radiological outcomes by a series of standard questionnaire and measurement.ResultsDue to the good exposure without any extensive soft-tissue dissection of the double-buttress plate fixation, the fractures in all 54 patients were healed and the treatment achieved greater than 90% of satisfactory-to-excellent rates of reduction. The mean time of bone union was 15.4 weeks (range, 12-30 weeks), and the mean time of full weight-bearing was 18.7 weeks (range, 14-26 weeks). At the final follow-up visit, no patients showed knee instability; the mean range of motion was 107.6° (range, 85°-130°). For all patients, no statistically significant difference in the functional outcomes was observed between their 6-months and final follow-up visits; or in the radiological findings between their immediate postoperative and final follow-up examinations.ConclusionDouble-buttress plate fixation is a feasible treatment option for bilcondylar and complex tibial plateau fractures. Although technically demanding, it offers reliable stability without additional postoperative adjuvant external fixation, and at the same time avoids extensive soft tissue dissection, allowing the early painless range of motion.

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