Kelp holdfast microclimates buffer invertebrate inhabitants from extreme temperatures.

Climate change is altering environmental conditions, with microclimates providing small-scale refuges within otherwise challenging environments. Durvillaea (southern bull kelp; rimurapa) is a genus of large intertidal fucoid algae, and some species harbour diverse invertebrate communities in their holdfasts. We hypothesised that animal-excavated Durvillaea holdfasts provide a thermal refuge for epibiont species, and tested this hypothesis using the exemplar species D. poha. Using a southern Aotearoa New Zealand population as a case-study, we found extreme temperatures outside the holdfast were 4.4 °C higher in summer and 6.9 °C lower in winter than inside the holdfast. A microclimate model of the holdfasts was built and used to forecast microclimates under 2100 conditions. Temperatures are predicted to increase by 2-3 °C, which may exceed the tolerances of D. poha. However, if D. poha or a similar congeneric persists, temperatures inside holdfasts will remain less extreme than the external environment. The thermal tolerances of two Durvillaea-associated invertebrates, the trochid gastropod Cantharidus antipodum and the amphipod Parawaldeckia kidderi, were also assessed; C. antipodum, but not P. kidderi, displayed metabolic depression at temperatures above and below those inside holdfasts, suggesting that they would be vulnerable outside the holdfast and with future warming. Microclimates, such as those within D. poha holdfasts or holdfasts of similar species, will therefore be important refuges for the survival of species both at the northern (retreating edge) and southern (expanding edge) limits of their distributions.

Science fiction or clinical reality: a review of the applications of artificial intelligence along the continuum of trauma care.

Artificial intelligence (AI) and machine learning describe a broad range of algorithm types that can be trained based on datasets to make predictions. The increasing sophistication of AI has created new opportunities to apply these algorithms within within trauma care. Our paper overviews the current uses of AI along the continuum of trauma care, including injury prediction, triage, emergency department volume, assessment, and outcomes. Starting at the point of injury, algorithms are being used to predict severity of motor vehicle crashes, which can help inform emergency responses. Once on the scene, AI can be used to help emergency services triage patients remotely in order to inform transfer location and urgency. For the receiving hospital, these tools can be used to predict trauma volumes in the emergency department to help allocate appropriate staffing. After patient arrival to hospital, these algorithms not only can help to predict injury severity, which can inform decision-making, but also predict patient outcomes to help trauma teams anticipate patient trajectory. Overall, these tools have the capability to transform trauma care. AI is still nascent within the trauma surgery sphere, but this body of the literature shows that this technology has vast potential. AI-based predictive tools in trauma need to be explored further through prospective trials and clinical validation of algorithms.

Stepping stones towards Antarctica: Switch to southern spawning grounds explains an abrupt range shift in krill.

Poleward range shifts are a global-scale response to warming, but these vary greatly among taxa and are hard to predict for individual species, localized regions or over shorter (years to decadal) timescales. Moving poleward might be easier in the Arctic than in the Southern Ocean, where evidence for range shifts is sparse and contradictory. Here, we compiled a database of larval Antarctic krill, Euphausia superba and, together with an adult database, it showed how their range shift is out of step with the pace of warming. During a 70-year period of rapid warming (1920s-1990s), distribution centres of both larvae and adults in the SW Atlantic sector remained fixed, despite warming by 0.5-1.0°C and losing sea ice. This was followed by a hiatus in surface warming and ice loss, yet during this period the distributions of krill life stages shifted greatly, by ~1000 km, to the south-west. Understanding the mechanism of such step changes is essential, since they herald system reorganizations that are hard to predict with current modelling approaches. We propose that the abrupt shift was driven by climatic controls acting on localized recruitment hotspots, superimposed on thermal niche conservatism. During the warming hiatus, the Southern Annular Mode index continued to become increasingly positive and, likely through reduced feeding success for larvae, this led to a precipitous decline in recruitment from the main reproduction hotspot along the southern Scotia Arc. This cut replenishment to the northern portion of the krill stock, as evidenced by declining density and swarm frequency. Concomitantly, a new, southern reproduction area developed after the 1990s, reinforcing the range shift despite the lack of surface warming. New spawning hotspots may provide the stepping stones needed for range shifts into polar regions, so planning of climate-ready marine protected areas should include these key areas of future habitat.

Paediatric supraventricular tachycardia patients potentially more at risk of developing psychological difficulties compared to healthy peers.

AIM: Assess executive and socio-emotional/behavioural functioning in paediatric supraventricular tachycardia (SVT) patients. METHODS: SVT patients aged 7-17 who had not undergone catheter ablation were included. Parents completed the Child Behaviour Checklist (CBCL/6-18) and the Behavior Rating Inventory of Executive Functioning (BRIEF). Participants age 11-17 years completed the Youth Self-Report (YSR/11-18) and the BRIEF Self-Report (BRIEF-SR). One-sample z test was used to compare questionnaire results to the average t-score range (M = 50, SD = 10). RESULTS: Thirty (18 female) children/adolescents participated (M = 12.6 years old, SD = 3.2 years) with a mean SVT onset age of 7 years (SD = 4.3 years). BRIEF and BRIEF-SR results suggested no difference in executive functioning from average. Mean t-scores of CBCL/6-18 and YSR/11-18 subscales Anxious/Depressed, Withdrawn/Depressed, Somatic Complaints, Thought Problems, Diagnostic and Statistical Manual of Mental Disorders (DSM) Affective Problems, DSM Anxiety Problems and DSM Somatic Problems were significantly elevated compared to average. YSR/11-18 subscales Social Problems, Attention Problems, Internalizing Problems, DSM ADHD Problems and DSM Oppositional Defiant Problems had elevated mean t-scores compared to average. Effect sizes were small to medium (0.2 ≤ d ≤ 0.8). CONCLUSION: Paediatric patients with SVT potentially have a greater risk of developing behaviour, especially internalizing, problems compared to similarly aged children/adolescents without SVT.

Habitat partitioning in Antarctic krill: Spawning hotspots and nursery areas.

Antarctic krill, Euphausia superba, have a circumpolar distribution but are concentrated within the south-west Atlantic sector, where they support a unique food web and a commercial fishery. Within this sector, our first goal was to produce quantitative distribution maps of all six ontogenetic life stages of krill (eggs, nauplii plus metanauplii, calyptopes, furcilia, juveniles, and adults), based on a compilation of all available post 1970s data. Using these maps, we then examined firstly whether "hotspots" of egg production and early stage nursery occurred, and secondly whether the available habitat was partitioned between the successive life stages during the austral summer and autumn, when krill densities can be high. To address these questions, we compiled larval krill density records and extracted data spanning 41 years (1976-2016) from the existing KRILLBASE-abundance and KRILLBASE-length-frequency databases. Although adult males and females of spawning age were widely distributed, the distribution of eggs, nauplii and metanauplii indicates that spawning is most intense over the shelf and shelf slope. This contrasts with the distributions of calyptope and furcilia larvae, which were concentrated further offshore, mainly in the Southern Scotia Sea. Juveniles, however, were strongly concentrated over shelves along the Scotia Arc. Simple environmental analyses based on water depth and mean water temperature suggest that krill associate with different habitats over the course of their life cycle. From the early to late part of the austral season, juvenile distribution moves from ocean to shelf, opposite in direction to that for adults. Such habitat partitioning may reduce intraspecific competition for food, which has been suggested to occur when densities are exceptionally high during years of strong recruitment. It also prevents any potential cannibalism by adults on younger stages. Understanding the location of krill spawning and juvenile development in relation to potentially overlapping fishing activities is needed to protect the health of the south-west Atlantic sector ecosystem.

Chronotropic incompetence as a risk predictor in children and young adults with catecholaminergic polymorphic ventricular tachycardia.

INTRODUCTION: Risk stratification tools for catecholaminergic polymorphic ventricular tachycardia (CPVT) are limited. The exercise stress test (EST) is the most important diagnostic and prognostic test. We aimed to determine whether heart rate (HR) and blood pressure (BP) response during EST were associated with the risk of arrhythmias. MATERIALS AND METHODS: We studied the association between HR and BP response and ventricular arrhythmia burden on EST in 20 CPVT patients. HR reserve values <80% and ≤62% were used to define chronotropic incompetence (CI) off and on therapy, respectively. Symptoms and ventricular arrhythmia score (VAS) in all patients with respect to CI and BP during index EST off therapy and on maximal therapy were compared. RESULTS: CI in CPVT patients off therapy was associated with a worse VAS during EST (P = .046). Patients with CI also more frequently presented with syncope and/or cardiac arrest compared to patients with a normal chronotropic response (P = .008). Once on therapy, patients with CI had similar VAS compared to patients without CI (P = .50), suggesting that treatment attenuates risk related to CI. Patients with CI also had a lower peak systolic BP (P = .041) which persisted on maximal therapy (P = .033). CONCLUSION: Untreated CPVT patients with CI have more ventricular arrhythmias than those without CI. This may serve as a simple disease prognosticator that can be modified by antiarrhythmic therapy. A mechanistic link between CI and arrhythmia susceptibility remains unknown. Larger studies are needed to confirm and establish the mechanism of these findings.

Implantable cardioverter-defibrillator use in catecholaminergic polymorphic ventricular tachycardia: A systematic review.

BACKGROUND: The implantable cardioverter-defibrillator (ICD) may be associated with a high risk of complications in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT). However, ICDs in this population have not been systematically evaluated. OBJECTIVE: The purpose of this study was to characterize the use and outcomes of ICDs in CPVT. METHODS: We conducted a systematic review using Embase, MEDLINE, PubMed, and Google Scholar to identify studies that included patients with CPVT who had an ICD. RESULTS: Fifty-three studies describing 1429 patients with CPVT were included. In total, 503 patients (35.2%) had an ICD (median age 15.0 years; interquartile range 11.0-21.0 years). Among ICD recipients with a reported medication status, 96.7% were prescribed ß-blockers and 13.2% flecainide. Sympathetic denervation was performed in 23.2%. Nearly half of patients received an ICD for primary prevention (47.3%), and 12.8% were prescribed optimal antiarrhythmic therapy. During follow-up, 40.1% had ≥1 appropriate shock, 20.8% experienced ≥1 inappropriate shock, 19.6% had electrical storm, and 7 patients (1.4%) died. An ICD-associated electrical storm was implicated in 4 deaths. Additional complications such as lead failure, endocarditis, or surgical revisions were observed in 96 of 296 patients (32.4%). A subanalysis of the 10 studies encompassing 330 patients with the most detailed ICD-related data showed similar trends. CONCLUSION: In this population with CPVT, ICDs were common and associated with a high burden of shocks and complications. The reliance on primary prevention ICDs, and poor uptake of adjuvant antiarrhythmic therapies, suggests that improved adherence to guideline-directed management could reduce ICD use and harm.

Functional characterization of a novel hERG variant in a family with recurrent sudden infant death syndrome: Retracting a genetic diagnosis.

Long QT syndrome (LQTS) is the most common cardiac ion channelopathy and has been found to be responsible for approximately 10% of sudden infant death syndrome (SIDS) cases. Despite increasing use of broad panels and now whole exome sequencing (WES) in the investigation of SIDS, the probability of identifying a pathogenic mutation in a SIDS victim is low. We report a family-based study who are afflicted by recurrent SIDS in which several members harbor a variant, p.Pro963Thr, in the C-terminal region of the human-ether-a-go-go (hERG) gene, published to be responsible for cases of LQTS type 2. Functional characterization was undertaken due to the variable phenotype in carriers, the discrepancy with published cases, and the importance of identifying a cause for recurrent deaths in a single family. Studies of the mutated ion channel in in vitro heterologous expression systems revealed that the mutation has no detectable impact on membrane surface expression, biophysical gating properties such as activation, deactivation and inactivation, or the amplitude of the protective current conducted by hERG channels during early repolarization. These observations suggest that the p.Pro963Thr mutation is not a monogenic disease-causing LQTS mutation despite evidence of co-segregation in two siblings affected by SIDS. Our findings demonstrate some of the potential pitfalls in post-mortem molecular testing and the importance of functional testing of gene variants in determining disease-causation, especially where the impacts of cascade screening can affect multiple generations.

The role of the autonomic nervous system in arrhythmias and sudden cardiac death.

The autonomic nervous system (ANS) is complex and plays an important role in cardiac arrhythmia pathogenesis. A deeper understanding of the anatomy and development of the ANS has shed light on its involvement in cardiac arrhythmias. Alterations in levels of Sema-3a and NGF, both growth factors involved in innervation patterning during development of the ANS, leads to cardiac arrhythmias. Dysregulation of the ANS, including polymorphisms in genes involved in ANS development, have been implicated in sudden infant death syndrome. Disruptions in the sympathetic and/or parasympathetic systems of the ANS can lead to cardiac arrhythmias and can vary depending on the type of arrhythmia. Simultaneous stimulation of both the sympathetic and parasympathetic systems is thought to lead to atrial fibrillation whereas increased sympathetic stimulation is thought to lead to ventricular fibrillation or ventricular tachycardia. In inherited arrhythmia syndromes, such as Long QT and Catecholaminergic Polymorphic Ventricular Tachycardia, sympathetic system stimulation is thought to lead to ventricular tachycardia, subsequent arrhythmias, and in severe cases, cardiac death. On the other hand, arrhythmic events in Brugada Syndrome have been associated with periods of high parasympathetic tone. Increasing evidence suggests that modulation of the ANS as a therapeutic strategy in the treatment of cardiac arrhythmias is safe and effective. Further studies investigating the involvement of the ANS in arrhythmia pathogenesis and its modulation for the treatment of cardiac arrhythmias is warranted.