Kv7 channels are upregulated during striatal neuron development and promote maturation of human iPSC-derived neurons.

Kv7 channels determine the resting membrane potential of neurons and regulate their excitability. Even though dysfunction of Kv7 channels has been linked to several debilitating childhood neuronal disorders, the ontogeny of the constituent genes, which encode Kv7 channels (KNCQ), and expression of their subunits have been largely unexplored. Here, we show that developmentally regulated expression of specific KCNQ mRNA and Kv7 channel subunits in mouse and human striatum is crucial to the functional maturation of mouse striatal neurons and human-induced pluripotent stem cell-derived neurons. This demonstrates their pivotal role in normal development and maturation, the knowledge of which can now be harnessed to synchronise and accelerate neuronal differentiation of stem cell-derived neurons, enhancing their utility for disease modelling and drug discovery.

Detection of Aß plaque-associated astrogliosis in Alzheimer's disease brain by spectroscopic imaging and immunohistochemistry.

Recent work using micro-Fourier transform infrared (µFTIR) imaging has revealed that a lipid-rich layer surrounds many plaques in post-mortem Alzheimer's brain. However, the origin of this lipid layer is not known, nor is its role in the pathogenesis of Alzheimer's disease (AD). Here, we studied the biochemistry of plaques in situ using a model of AD. We combined FTIR, Raman and immunofluorescence images, showing that astrocyte processes co-localise with the lipid ring surrounding many plaques. We used µFTIR imaging to rapidly measure chemical signatures of plaques over large fields of view, and selected plaques for higher resolution analysis with Raman microscopy. Raman maps showed similar lipid rings and dense protein cores as in FTIR images, but also revealed cell bodies. We confirmed the presence of plaques using amylo-glo staining, and detected astrocytes using immunohistochemistry, revealing astrocyte co-localisation with lipid rings. This work is important because it correlates biochemical changes surrounding the plaque with the biological process of astrogliosis.

Using a Theory-Driven Approach to Manage the Relocation of an Intensive Care Unit: An Exemplar.

Proactive planning and managing moving from old to newly built hospitals, and the relocation process of patients for complex specialized units such as intensive care units, are necessary for both patient safety and staff well-being. This article provides an exemplar for how theory can be used to facilitate a positive relocation experience. Using change management theory, a systematic approach to cocreate implementation strategy among researchers and clinicians was critical to the success of this project.

Forced cell cycle exit and modulation of GABAA, CREB, and GSK3ß signaling promote functional maturation of induced pluripotent stem cell-derived neurons.

Although numerous protocols have been developed for differentiation of neurons from a variety of pluripotent stem cells, most have concentrated on being able to specify effectively appropriate neuronal subtypes and few have been designed to enhance or accelerate functional maturity. Of those that have, most employ time courses of functional maturation that are rather protracted, and none have fully characterized all aspects of neuronal function, from spontaneous action potential generation through to postsynaptic receptor maturation. Here, we describe a simple protocol that employs the sequential addition of just two supplemented media that have been formulated to separate the two key phases of neural differentiation, the neurogenesis and synaptogenesis, each characterized by different signaling requirements. Employing these media, this new protocol synchronized neurogenesis and enhanced the rate of maturation of pluripotent stem cell-derived neural precursors. Neurons differentiated using this protocol exhibited large cell capacitance with relatively hyperpolarized resting membrane potentials; moreover, they exhibited augmented: 1) spontaneous electrical activity; 2) regenerative induced action potential train activity; 3) Na(+) current availability, and 4) synaptic currents. This was accomplished by rapid and uniform development of a mature, inhibitory GABAAreceptor phenotype that was demonstrated by Ca(2+) imaging and the ability of GABAAreceptor blockers to evoke seizurogenic network activity in multielectrode array recordings. Furthermore, since this protocol can exploit expanded and frozen prepatterned neural progenitors to deliver mature neurons within 21 days, it is both scalable and transferable to high-throughput platforms for the use in functional screens.

Improving and accelerating the differentiation and functional maturation of human stem cell-derived neurons: role of extracellular calcium and GABA.

Neurons differentiated from pluripotent stem cells using established neural culture conditions often exhibit functional deficits. Recently, we have developed enhanced media which both synchronize the neurogenesis of pluripotent stem cell-derived neural progenitors and accelerate their functional maturation; together these media are termed SynaptoJuice. This pair of media are pro-synaptogenic and generate authentic, mature synaptic networks of connected forebrain neurons from a variety of induced pluripotent and embryonic stem cell lines. Such enhanced rate and extent of synchronized maturation of pluripotent stem cell-derived neural progenitor cells generates neurons which are characterized by a relatively hyperpolarized resting membrane potential, higher spontaneous and induced action potential activity, enhanced synaptic activity, more complete development of a mature inhibitory GABAA receptor phenotype and faster production of electrical network activity when compared to standard differentiation media. This entire process - from pre-patterned neural progenitor to active neuron - takes 3 weeks or less, making it an ideal platform for drug discovery and disease modelling in the fields of human neurodegenerative and neuropsychiatric disorders, such as Huntington's disease, Parkinson's disease, Alzheimer's disease and Schizophrenia.

Successful treatment of failing biological prosthesis because of "Stent creep" with valve-in-valve transcatheter aortic valve implantation.

INTRODUCTION: Stent creep is an uncommon mode of structural deterioration of bioprosthetic heart valves defined by a permanent inward deflection of the stent posts. This may occur because of valve over-sizing and leads to intrinsic valve stenosis. It has been described in older generation of bioprosthesis and was thought not to occur in modern devices. METHODS: We describe three patients who were referred for bioprosthetic valve degeneration with presumed aortic stenosis. Investigations demonstrated mid valvular gradient predominantly because of stent creep. We performed valve-in-valve TAVI with Edward SAPIEN prosthesis. RESULTS: Median age was 84 and logistic EuroSCORE 34.4. All patients had degenerated bioprosthesis with mean implant duration of 5.6 years. Two patients had Carpentier Edwards Perimount prosthesis (19 and 23 mm) and one patient had a Mitroflow (21 mm). Mean gradients were 33, 54, and 22 mm Hg. About 23 mm Edward SAPIEN valve was implanted in all cases with immediate improvement in haemodynamics with mean gradient reduction to 10, 17, and 8 mm Hg, respectively. The mean aortic valve area increased from 0.63 to 1.76cm(2) . There were no serious adverse events. The patients improved from NYHA III/IV to I/II post procedure and remain well at median follow-up of 24-months. DISCUSSION: Stent creep is an uncommon mode of structural deterioration in bioprosthetic heart valves. It has been described in the previous generation of bioprosthesis. It is important to distinguish leaflet dysfunction and stent creep. By forcing the stent posts outwards a balloon expandable TAVI device can be used to treat this condition.

Prevalence, characteristics and clinical impact of work-related musculoskeletal pain in echocardiography.

BACKGROUND: Work-related musculoskeletal pain (WRMSP) is increasingly recognised in cardiac ultrasound practice. WRMSP can impact workforce health, productivity and sustainability. We sought to investigate the prevalence, characteristics and clinical impact of WRMSP. METHODS: Prospective electronic survey of 157 echocardiographers in 10 institutions. Data acquired on demographics, experience, working environment/pattern, WRMSP location, severity and pattern, the impact on professional, personal life and career. RESULTS: 129/157 (82%) echocardiographers completed the survey, of whom 109 (85%) reported WRMSP and 55 (43%) reported work taking longer due to WRMSP. 40/129 (31%) required time off work. 78/109 (60%) reported sleep disturbance with 26/78 (33%) of moderate or severe severity. 56/129 (45%) required medical evaluation of their WRMSP and 25/129 (19%) received a formal diagnosis of musculoskeletal injury. Those with 11+ years of experience were significantly more likely to receive a formal diagnosis of WRMSP (p = 0.002) and require medication (p = 0.006) compared to those with 10 years or less experience. CONCLUSION: WRMSP is very common amongst echocardiographers, with a fifth having a related musculoskeletal injury. WRMSP has considerable on impact on personal, social and work-related activities. Strategies to reduce the burden of WRMSP are urgently required to ensure sustainability of the workforce and patient access to imaging.

Transaortic Transcatheter Aortic valve implantation using Edwards Sapien valve: a novel approach.

OBJECTIVES: To evaluate feasibility and outcome of Transoartic Transcatheter Sapien valve implantation. BACKGROUND: Transcatheter Aortic valve implantation (TAVI) using the Edwards SAPIEN device (Edwards LifeScience, Irvine, CA) is usually performed via the transfemoral (TF) or transapical (TA) routes. Some patients are not suitable for these approaches. We report our experience with the novel transaortic (TAo) approach via a partial upper sternotomy and discuss the advantages and future applications. METHODS: Between January 2008 to March 2011 193 patients with severe aortic stenosis underwent TAVI with the Edwards SAPIEN bioprosthesis at the St. Thomas' Hospital, London. 108 patients were unable to undergo a TF-TAVI and of those 17 were accepted for a TAo-TAVI on the basis of anatomy, risk, LV function, and significant respiratory disease. RESULTS: The TAo-TAVI group (n = 17) had more prevalent respiratory disease than the TA-TAVI group (47.0% vs. 18.7%, P = 0.011). Otherwise the groups were similar in demographics and history. Despite this the 30 day mortalities were not significantly different between the groups (TAo-TAVI 4.3% at 30 days versus TA-TAVI 7.7%, P = 0.670). There were no significant differences in procedural complications. CONCLUSIONS: The TA-TAVI approach may not be desirable in patients with severe chest deformity, poor lung function or poor left ventricular function. TAo-TAVI via a partial sternotomy is safe and feasible in these patients.

Anatomy of a Transcatheter Mitral Valve Service.

Transcatheter mitral therapies offer treatment options to selected patients who are unable to undergo open procedures due to prohibitive surgical risk. Data detailing the design and structure of transcatheter mitral services to ensure appropriate patient selection and tailored management strategies is lacking. We report our initial experience of developing and running a purpose-built transcatheter mitral service. The nature and number of referral sources, the multi-disciplinary make-up of the dedicated Mitral Heart Team and the use of integrative imaging assessment with incorporation of computational solutions are discussed. In addition, a summary of the clinical decision-making process is presented. This report sets out a framework from which future clinics can evolve to improve and streamline the delivery of transcatheter mitral therapies.

Multimodality Imaging in Valvular Structural Interventions.

Structural valvular interventions have skyrocketed in the past decade with new devices becoming available and indications for patients who would previously have been deemed inoperable. Furthermore, while echocardiography is the main imaging tool and the first line for patient screening, cardiac magnetic resonance and CT are now essential tools in pre-planning and post-procedural follow-up. This review aims to address imaging modalities and their scope in aortic, mitral and tricuspid structural valvular interventions, including multimodality imaging. Pulmonary valve procedures, which are mostly carried out in patients with congenital problems, are discussed. This article presents a guide on individualised imaging approcahes on each of the available interventional procedures.

"Gazing Into the Abyss": Transcatheter Mitral Valve-in-Valve Implantation Through a Cavernous Left Atrium.

We describe the case of a 73-year-old woman presenting with heart failure, a degenerating bioprosthetic mitral valve, and severely dilated left atrium, and highlight the role of multimodality imaging in planning transseptal transcatheter mitral valve-in-valve implantation. (Level of Difficulty: Advanced.).

Transcatheter aortic valve implantation for severe aortic stenosis-a new paradigm for multidisciplinary intervention: a prospective cohort study.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) is an alternative treatment option for patients with aortic stenosis deemed high risk or unsuitable for aortic valve replacement. The aim of this study was to assess the feasibility of TAVI in elderly patients, the delivery of this technology with a multidisciplinary approach, and the use of traditional surgical scoring systems. METHODS: One hundred fifty-one consecutive patients (mean age 82.6 +/- 7.3 years) with severe aortic stenosis underwent TAVI with the Edwards Lifesciences (Irvine, CA) Sapien bioprosthesis using the transapical (n = 84; 56%) or transfemoral (n = 67; 44%) approach from August 2007 to September 2009 at King's Health Partners, London, United Kingdom. We analyzed procedural outcome, complications, functional status, and midterm outcome of patients. RESULTS: The multidisciplinary team comprised interventional cardiologists, cardiothoracic surgeons, imaging specialists, cardiac anesthetists, and specialist nurses. Seventy percent of patients were in New York Heart Association class III/IV, and logistic EuroSCORE was 21.6 +/- 11.9. Procedural success was achieved in 98%. Postoperative complications included stroke (6%), complete atrioventricular block (5.3%), renal failure requiring hemofiltration (9.3%), and vascular injury (8.6%). Overall 30-day mortality was 9.9% (n = 15). The logistic EuroSCORE was a predictor of short-term mortality (logistic regression model, P < .05). Thirty-day mortality post-TAVI for patients with logistic EuroSCORE <20, 20 to 40, and >40 was 5.4%, 13.2%, and 22.2%, respectively. CONCLUSIONS: Transcatheter aortic valve implantation is a feasible treatment option in this patient group with promising short/medium-term results. Renal failure is the commonest short-term complication, and the incidence of vascular complications remains high. Risk prediction/case selection remains challenging, and a multidisciplinary team approach appears to be helpful in appropriate patient selection.

Receptor-mediated suppression of potassium currents requires colocalization within lipid rafts.

Expression of KCNQ2/3 (Kv7.2 and -7.3) heteromers underlies the neuronal M current, a current that is suppressed by activation of a variety of receptors that couple to the hydrolysis of phosphatidylinositol 4,5-bisphosphate. Expression of Kv7.2/7.3 channels in human embryonic kidney (HEK) 293 cells produced a noninactivating potassium current characteristic of M current. Muscarinic receptors endogenous to HEK293 cells were identified as being M3 by pharmacology and Western blotting, producing a rise of intracellular calcium ([Ca2+](i)) upon activation. Activation of these endogenous muscarinic receptors however, failed to suppress expressed Kv7.2/7.3 current. Current suppression was reconstituted by coexpression of HA-tagged muscarinic m1 or m3 receptors. Examination of membrane fractions showed that both expressed receptors and Kv7.2 and -7.3 channel subunits resided within lipid rafts. Disruption of lipid rafts by pretreatment of cells expressing either m1 or m3 muscarinic receptors with methyl-beta-cyclodextrin produced a loss of localization of proteins within lipid raft membrane fractions. This pretreatment also abolished both the increase of [Ca2+](i) and suppression of expressed Kv7.2/7.3 current evoked by activation of expressed m1 or m3 muscarinic receptors. A similar loss of muscarinic receptor-mediated suppression of M current native to rat dorsal root ganglion neurons was observed after incubating dissociated cells with methyl-beta-cyclodextrin. These data suggested that lipid rafts colocalized both muscarinic receptors and channel subunits to enable receptor-mediated suppression of channel activity, a spatial colocalization that enables specificity of coupling between receptor and ion channel.

Transaortic transcatheter aortic valve implantation using the Lotus valve: first-in-man experience.

AIMS: To demonstrate the feasibility of implanting the Lotus second-generation transcatheter heart valve (THV) (designed for a transfemoral procedure) via a transaortic approach. METHODS AND RESULTS: We describe a case with severe aortic stenosis in the presence of small calibre and calcified femoral access and severe chronic obstructive pulmonary disease. The transaortic approach was the ideal approach for this patient and we successfully implanted a 25 mm Lotus valve without any complication. CONCLUSIONS: The transaortic access is a feasible and safe alternative in patients who have suboptimal iliofemoral conduits and who will benefit from the unique features of the Lotus THV.

Selective activation of heteromeric SK channels contributes to action potential repolarization in mouse atrial myocytes.

BACKGROUND: Activation of small conductance calcium-activated potassium (SK) channels is proposed to contribute to repolarization of the action potential in atrial myocytes. This role is controversial, as these cardiac SK channels appear to exhibit an uncharacteristic pharmacology. OBJECTIVES: The objectives of this study were to resolve whether activation of SK channels contributes to atrial action potential repolarization and to determine the likely subunit composition of the channel. METHODS: The effect of 2 SK channel inhibitors was assessed on outward current evoked in voltage clamp and on action potential duration in perforated patch and whole-cell current clamp recording from acutely isolated mouse atrial myocytes. The presence of SK channel subunits was assessed using immunocytochemistry. RESULTS: A significant component of outward current was reduced by the SK channel blockers apamin and UCL1684. Block by apamin displayed a sensitivity indicating that this current was carried by homomeric SK2 channels. Action potential duration was significantly prolonged by UCL1684, but not by apamin. This effect was accompanied by an increase in beat-to-beat variability and action potential triangulation. This pharmacology was matched by that of expressed heteromeric SK2-SK3 channels in HEK293 cells. Immunocytochemistry showed that atrial myocytes express both SK2 and SK3 channels with an overlapping expression pattern. CONCLUSION: Only proposed heteromeric SK2-SK3 channels are physiologically activated to contribute to action potential repolarization, which is indicated by the difference in pharmacology of evoked outward current and prolongation of atrial action potential duration. The effect of blocking this channel on the action potential suggests that SK channel inhibition during cardiac function has the potential to be proarrhythmic.

Early and late changes in quality of life following transcatheter aortic valve implantation using the transfemoral and transapical approaches.

AIMS: To evaluate the effects of access route upon clinical results and quality of life (QoL) in patients undergoing either transfemoral (TF-TAVI) or transapical balloon-expandable transcatheter aortic valve implantation (TA-TAVI) in the real world. METHODS AND RESULTS: A prospective analysis was performed upon 264 consecutive patients receiving TF-TAVI or TA-TAVI. QoL was assessed using the EQ-5D questionnaire. At baseline, TA-TAVI patients reported significantly more problems in mobility, self-care, usual activities and lower overall health status domains (p<0.01 for all). At 30 days, the TF-TAVI group reported fewer problems with usual activity (p=0.01) and pain/discomfort (p<0.01), and higher EQ-5D index and visual analogue scale (VAS) (p=0.01 and p<0.01, respectively) than the TA-TAVI group. Nevertheless, the absolute improvements (ΔEQ-5D index and ΔEQ-5D VAS) were larger in the TA-TAVI group, with most dramatically marked QoL absolute improvements (p<0.01 and p=0.02, respectively). By one year, notwithstanding higher all-cause mortality in the sicker TA-TAVI group, there were no differences between groups in any EQ-5D domain. Indeed, surviving TA-TAVI group's greater absolute improvements remained (p<0.01). CONCLUSIONS: QoL is greater at the earlier time point of 30 days in the TF-TAVI cohort but equatable by one year. However, the magnitude of improvement in QoL is greater in the TA-TAVI patients at both 30 days and one year.

The effect of coronary artery disease defined by quantitative coronary angiography and SYNTAX score upon outcome after transcatheter aortic valve implantation (TAVI) using the Edwards bioprosthesis.

AIMS: We sought to evaluate the effects of significant coronary artery disease (CAD) upon outcome after transcatheter aortic valve implantation (TAVI). METHODS AND RESULTS: We performed a retrospective study of 271 consecutive patients undergoing TAVI using either the Edwards SAPIEN or Edwards SAPIEN XT valve. Pre-procedural coronary angiograms were analysed by quantitative coronary angiography (defining significant CAD as a stenosis of ≥70% or ≥50% if in the left main stem or a vein graft). Ninety-three out of 271 patients had significant CAD. There was no difference in mortality at 30 days or 12 months between the two groups (6.7% vs. 7.5% and 21.5% vs. 23.7%; log-rank p=0.805). A secondary analysis using the SYNTAX algorithm of coronary anatomy complexity was performed on 189 patients. Those in the high SYNTAX score (>33) group had higher mortality at 30 days and 12 months (14.3% and 57.1%) than the low (5.2% and 23.3%) and intermediate-risk groups (11.1% and 22.2%; log-rank p=0.007). ROC analysis identified a SYNTAX score of >9 at the time of TAVI as the optimal cut-off, with an independent association with mortality (HR 1.95 [95% CI: 1.21-3.13]; p=0.006). Patients with a SYNTAX score >9 had greater 30-day, 12-month and overall mortalities than those with a SYNTAX score <9 (3.7% vs. 11.3% and 20.7% vs. 34.3%; log-rank p=0.005). CONCLUSIONS: Significant CAD, as defined using "real-world" QCA margins, did not have a significant effect upon mortality after TAVI for severe aortic stenosis. However, higher-risk SYNTAX groups, including those with a score >9, had increased mortality.

Normal values of left ventricular systolic and diastolic function derived from signal-averaged acoustic quantification waveforms: a multicenter study.

Automated border-detection techniques such as acoustic quantification have proven accurate and useful for quantifying left ventricular (LV) function. We acquired LV acoustic quantification waveforms from the parasternal short-axis window in 140 healthy patients in the age range of 16 to 78 years. Signal-averaged waveforms were analyzed for parameters of systolic and diastolic performance. The average fractional area change was 54 +/- 12%, and there were no significant changes in LV systolic function in the age range studied. There were significant changes in diastolic parameters with aging. The percentage of contribution to total LV filling occurring during atrial filling nearly tripled during the 6 decades studied, from 13% in the youngest cohort to 36% in the eighth decade of life. This study provides normal reference values for systolic and diastolic parameters of LV function determined from signal-averaged acoustic quantification waveforms acquired from the parasternal short-axis view in adult and adolescent patients over a wide age range.

Use of balloon expandable transcatheter valves for valve-in-valve implantation in patients with degenerative stentless aortic bioprostheses: Technical considerations and results.

OBJECTIVE: Transcatheter valve-in-valve is an accepted treatment in high-risk patients with degenerative stented bioprostheses in the aortic position. Experience in treating stentless valves is, however, limited. Our aim was to determine the feasibility and single-center outcome of balloon expandable SAPIEN valve placement in degenerated stentless aortic valve bioprostheses. METHODS: From February 2010 to January 2014, 10 patients with failing stentless bioprostheses underwent transcatheter aortic valve implantation using the Edwards SAPIEN transcatheter heart valve (SAPIEN, SAPIEN XT, and SAPIEN 3) at our institution. Seven patients had valve failure due to regurgitation and three to stenosis. The mean age was 73.3 ± 15.0 years. The mean logistic EuroSCORE was 31.8 ± 20.3, and the Society of Thoracic Surgeons score was 7.6 ± 5.4. RESULTS: Technical success was achieved in 9 of 10 patients. One patient required immediate placement of a second valve owing to low placement of the first. Two intraoperative complications developed that needed additional procedures. One patient underwent immediate repair of a right ventricular perforation from a pacing lead, the other, reexploration for epicardial bleeding. No deaths occurred. The median length of stay was 8.5 days (range, 3-44). The mean follow-up was 8.1 months (range, 1-21). No late reoperations or reinterventions were required. CONCLUSIONS: Transcatheter aortic valve implantation after previous stentless aortic valve replacement is technically demanding but a safe and feasible approach. The early results were excellent, with consistent improvement in hemodynamics. Prospective long-term follow-up in larger series is needed to evaluate this technique further.