SPEAR Trial: Smartphone Pediatric ElectrocARdiogram Trial

Objectives

Smartphone-enabled ECG devices have the potential to improve patient care by enabling remote ECG assessment of patients with potential and diagnosed arrhythmias. This prospective study aimed to assess the usefulness of pediatric ECG tracings generated by the AliveCor device (Oklahoma City, OK) and to assess user satisfaction.

Study Design

Enrolled pediatric patients with documented paroxysmal arrhythmia used the AliveCor device over a yearlong study period. Pediatric electrophysiologists reviewed all transmitted ECG tracings. Patient completed surveys were analyzed to assess user satisfaction.

Results

35 patients were enrolled with the following diagnoses: supraventricular tachycardia (SVT, 57%), atrial fibrillation (AF, 11%), ectopic atrial tachycardia (EAT, 6%), atrial tachycardia (AT, 3%), and ventricular tachycardia (VT, 23%). A total of 238 tracings were received from 20 patients, 96% of which were of diagnostic quality for sinus rhythm, sinus tachycardia, SVT, and AF. 126 patient satisfaction surveys (64% from parents) were completed. 98% of the survey responses indicated that it was easy to obtain tracings, 93% found it easy to transmit the tracings, 98% showed added comfort in managing arrhythmia by having the device, and 93% showed interest in continued use of the device after the study period ended.

Conclusions

Smartphone-enabled ECG devices can generate tracings of diagnostic quality in children. User satisfaction was extremely positive. Use of the device to manage certain patients with AF and SVT showcases the future role of remote ECGs in the successful outpatient management of arrhythmias in children by potentially reducing Emergency Department visits and healthcare costs.     

Isoproterenol Acts as a Biased Agonist of the Alpha-1A-Adrenoceptor that Selectively Activates the MAPK/ERK Pathway

The α_1A-AR is thought to couple predominantly to the Gα_q/PLC pathway and lead to phosphoinositide hydrolysis and calcium mobilization, although certain agonists acting at this receptor have been reported to trigger activation of arachidonic acid formation and MAPK pathways. For several G protein-coupled receptors (GPCRs) agonists can manifest a bias for activation of particular effector signaling output, i.e. not all agonists of a given GPCR generate responses through utilization of the same signaling cascade(s). Previous work with Gα_q coupling-defective variants of α_1A-AR, as well as a combination of Ca²⁺ channel blockers, uncovered cross-talk between α_1A-AR and β₂-AR that leads to potentiation of a Gα_q-independent signaling cascade in response to α_1A-AR activation. We hypothesized that molecules exist that act as biased agonists to selectively activate this pathway. In this report, isoproterenol (Iso), typically viewed as β-AR-selective agonist, was examined with respect to activation of α_1A-AR. α_1A-AR selective antagonists were used to specifically block Iso evoked signaling in different cellular backgrounds and confirm its action at α_1A-AR. Iso induced signaling at α_1A-AR was further interrogated by probing steps along the Gα_q /PLC, Gα_s and MAPK/ERK pathways. In HEK-293/EBNA cells transiently transduced with α_1A-AR, and CHO_α_1A-AR stable cells, Iso evoked low potency ERK activity as well as Ca²⁺ mobilization that could be blocked by α_1A-AR selective antagonists. The kinetics of Iso induced Ca²⁺ transients differed from typical Gα_q- mediated Ca²⁺ mobilization, lacking both the fast IP₃R mediated response and the sustained phase of Ca²⁺ re-entry. Moreover, no inositol phosphate (IP) accumulation could be detected in either cell line after stimulation with Iso, but activation was accompanied by receptor internalization. Data are presented that indicate that Iso represents a novel type of α_1A-AR partial agonist with signaling bias toward MAPK/ERK signaling cascade that is likely independent of coupling to Gα_q.     

FORGE Canada Consortium: Outcomes of a 2-Year National Rare-Disease Gene-Discovery Project

Inherited monogenic disease has an enormous impact on the well-being of children and their families. Over half of the children living with one of these conditions are without a molecular diagnosis because of the rarity of the disease, the marked clinical heterogeneity, and the reality that there are thousands of rare diseases for which causative mutations have yet to be identified. It is in this context that in 2010 a Canadian consortium was formed to rapidly identify mutations causing a wide spectrum of pediatric-onset rare diseases by using whole-exome sequencing. The FORGE (Finding of Rare Disease Genes) Canada Consortium brought together clinicians and scientists from 21 genetics centers and three science and technology innovation centers from across Canada. From nation-wide requests for proposals, 264 disorders were selected for study from the 371 submitted; disease-causing variants (including in 67 genes not previously associated with human disease; 41 of these have been genetically or functionally validated, and 26 are currently under study) were identified for 146 disorders over a 2-year period. Here, we present our experience with four strategies employed for gene discovery and discuss FORGE’s impact in a number of realms, from clinical diagnostics to the broadening of the phenotypic spectrum of many diseases to the biological insight gained into both disease states and normal human development. Lastly, on the basis of this experience, we discuss the way forward for rare-disease genetic discovery both in Canada and internationally.     

Antagonism of Beclin 1‐dependent autophagy by BCL‐2 at the endoplasmic reticulum requires NAF‐1

In addition to mitochondria, BCL‐2 is located at the endoplasmic reticulum (ER) where it is a constituent of several distinct complexes. Here, we identify the BCL‐2‐interacting protein at the ER, nutrient‐deprivation autophagy factor‐1 (NAF‐1)—a bitopic integral membrane protein whose defective expression underlies the aetiology of the neurodegenerative disorder Wolfram syndrome 2 (WFS2). NAF‐1 contains a two iron–two sulphur coordinating domain within its cytosolic region, which is necessary, but not sufficient for interaction with BCL‐2. NAF‐1 is displaced from BCL‐2 by the ER‐restricted BH3‐only protein BIK and contributes to regulation of BIK‐initiated autophagy, but not BIK‐dependent activation of caspases. Similar to BCL‐2, NAF‐1 is found in association with the inositol 1,4,5‐triphosphate receptor and is required for BCL‐2‐mediated depression of ER Ca²⁺ stores. During nutrient deprivation as a physiological stimulus of autophagy, BCL‐2 is known to function through inhibition of the autophagy effector and tumour suppressor Beclin 1. NAF‐1 is required in this pathway for BCL‐2 at the ER to functionally antagonize Beclin 1‐dependent autophagy. Thus, NAF‐1 is a BCL‐2‐associated co‐factor that targets BCL‐2 for antagonism of the autophagy pathway at the ER.     

Transformation of potato via Agrobacterium coated microparticle bombardment

The transformation of potato (Solanum tuberosum L. cv. Désirée) was extended by the Agrobacterium-mediated biolistic method. Using this approach transgenic shoots could be obtained at a similar frequency to that achieved through conventional biolistics. Leaves from shoot cultures were bombarded with gold particles coated in Agrobacterium tumefaciens cells harboring a binary plasmid encoding three genes of interest in the T-DNA. Nine shoots were obtained from 20 shots, with selection of transgenic shoots on a series of media containing progressively increasing concentrations of hygromycin from 5 to 20 mg dm⁻³.     

Evaluation of diverse soybean germplasm for root growth and architecture

Root characteristics of soybean (Glycine max (L.) Merr.) improve drought avoidance by increasing water uptake from the soil profile. Screening genotypes for improved root architecture without breaking the taproots or losing lateral roots is a challenge. Due to difficulty in separating roots from field or potting soil, a rapid and effective screening method with a suitable growth medium to assess root characteristics under controlled conditions needs to be established. We describe two screening techniques “the cone system” and “the tube system” using turface:sand medium. In the cone system thirty four soybean lines including cultivars and exotic plant introduction (PI) lines were evaluated for tap root length and root biomass, 12 days after sowing. Eight replications per line were grown in a growth chamber. Significant differences among genotypes for tap root length were detected by the cone system. Validity of results from the cone system was tested by evaluating root growth 21 days after planting for eight lines in the tube system. A coefficient of determination of 0.72 indicated good agreement between the two screening systems for evaluating genotypes for rooting depth. The cone system will be a useful method to easily and rapidly assess soybean genotypes for root growth.