Acute Adenoviral Infection Elicits an Arrhythmogenic Substrate Prior to Myocarditis

BACKGROUND

Viral cardiac infection represents a significant clinical challenge encompassing several etiological agents, disease stages, complex presentation, and a resulting lack of mechanistic understanding. Myocarditis is a major cause of sudden cardiac death in young adults, where current knowledge in the field is dominated by later disease phases and pathological immune responses. However, little is known regarding how infection can acutely induce an arrhythmogenic substrate before significant immune responses. Adenovirus is a leading cause of myocarditis, but due to species specificity, models of infection are lacking, and it is not understood how adenoviral infection may underlie sudden cardiac arrest. Mouse adenovirus type-3 was previously reported as cardiotropic, yet it has not been utilized to understand the mechanisms of cardiac infection and pathology.

METHODS

We have developed mouse adenovirus type-3 infection as a model to investigate acute cardiac infection and molecular alterations to the infected heart before an appreciable immune response or gross cardiomyopathy.

RESULTS

Optical mapping of infected hearts exposes decreases in conduction velocity concomitant with increased Cx43Ser368 phosphorylation, a residue known to regulate gap junction function. Hearts from animals harboring a phospho-null mutation at Cx43Ser368 are protected against mouse adenovirus type-3-induced conduction velocity slowing. Additional to gap junction alterations, patch clamping of mouse adenovirus type-3-infected adult mouse ventricular cardiomyocytes reveals prolonged action potential duration as a result of decreased IK1 and IKs current density. Turning to human systems, we find human adenovirus type-5 increases phosphorylation of Cx43Ser368 and disrupts synchrony in human induced pluripotent stem cell-derived cardiomyocytes, indicating common mechanisms with our mouse whole heart and adult cardiomyocyte data.

CONCLUSIONS

Together, these findings demonstrate that adenoviral infection creates an arrhythmogenic substrate through direct targeting of gap junction and ion channel function in the heart. Such alterations are known to precipitate arrhythmias and likely contribute to sudden cardiac death in acutely infected patients.

Cardiac-Specific Deletion of Scn8a Mitigates Dravet Syndrome-Associated Sudden Death in Adults

BACKGROUND

Sudden unexpected death in epilepsy (SUDEP) is a fatal complication experienced by otherwise healthy epilepsy patients. Dravet syndrome (DS) is an inherited epileptic disorder resulting from loss of function of the voltage-gated sodium channel, NaV 1.1, and is associated with particularly high SUDEP risk. Evidence is mounting that NaVs abundant in the brain also occur in the heart, suggesting that the very molecular mechanisms underlying epilepsy could also precipitate cardiac arrhythmias and sudden death. Despite marked reduction of NaV 1.1 functional expression in DS, pathogenic late sodium current (INa,L) is paradoxically increased in DS hearts. However, the mechanisms by which DS directly impacts the heart to promote sudden death remain unclear.

OBJECTIVES

In this study the authors sought to provide evidence implicating remodeling of Na+ - and Ca2+ -handling machinery, including NaV 1.6 and Na+/Ca2+exchanger (NCX) within transverse (T)-tubules in DS-associated arrhythmias.

METHODS

The authors undertook scanning ion conductance microscopy (SICM)-guided patch clamp, super-resolution microscopy, confocal Ca2+ imaging, and in vivo electrocardiography studies in Scn1a haploinsufficient murine model of DS.

RESULTS

DS promotes INa,L in T-tubular nanodomains, but not in other subcellular regions. Consistent with increased NaV activity in these regions, super-resolution microscopy revealed increased NaV 1.6 density near Ca2+release channels, the ryanodine receptors (RyR2) and NCX in DS relative to WT hearts. The resulting INa,L in these regions promoted aberrant Ca2+ release, leading to ventricular arrhythmias in vivo. Cardiac-specific deletion of NaV 1.6 protects adult DS mice from increased T-tubular late NaV activity and the resulting arrhythmias, as well as sudden death.

CONCLUSIONS

These data demonstrate that NaV 1.6 undergoes remodeling within T-tubules of adult DS hearts serving as a substrate for Ca2+ -mediated cardiac arrhythmias and may be a druggable target for the prevention of SUDEP in adult DS subjects.

Realizing the price of academic freedom

Since 2010, the number of life science doctoral graduates opting into academic postdoctoral employment has steadily declined. In recent years, this decline has made routine headlines in academic news cycles, and faculty members, universities, and funding bodies alike have begun to take notice. In November 2022, the National Institutes of Health (NIH) convened a special interest group to address the problems in postdoctoral recruitment and retention. In response, the American Physiological Society Science Policy Committee highlighted several key issues in postdoctoral training and working conditions and offered the NIH solutions to consider. There are known issues that affect postdoctoral recruitment and retention efforts: low wages relative to other employment sectors, a heavy workload, and poor job prospects to name a few. Unfortunately, these concerns are frequently dismissed as "the price of doing business in academia," and postdoctoral scholars are promised that if they overcome the trials and tribulations of this training period, the reward at the end, a career with academic freedom to pursue your own interests, justifies the means. However, academic freedom cannot and should not be used as the band-aid in a system where most of us will never actually experience academic freedom. Instead, we should systematically embrace solutions that improve the personal and professional health of early career researchers in all levels of training and independence if the goal is to truly shore up the academic workforce.

Unraveling Impacts of Chamber-Specific Differences in Intercalated Disc Ultrastructure and Molecular Organization on Cardiac Conduction

BACKGROUND

Propagation of action potentials through the heart coordinates the heartbeat. Thus, intercalated discs, specialized cell-cell contact sites that provide electrical and mechanical coupling between cardiomyocytes, are an important target for study. Impaired propagation leads to arrhythmias in many pathologies, where intercalated disc remodeling is a common finding, hence the importance and urgency of understanding propagation dependence on intercalated disc structure. Conventional modeling approaches cannot predict changes in propagation elicited by perturbations that alter intercalated disc ultrastructure or molecular organization, because of lack of quantitative structural data at subcellular through nano scales.

OBJECTIVES

This study sought to quantify intercalated disc structure at these spatial scales in the healthy adult mouse heart and relate them to chamber-specific properties of propagation as a precursor to understanding the effects of pathological intercalated disc remodeling.

METHODS

Using super-resolution light microscopy, electron microscopy, and computational image analysis, we provide here the first ever systematic, multiscale quantification of intercalated disc ultrastructure and molecular organization.

RESULTS

By incorporating these data into a rule-based model of cardiac tissue with realistic intercalated disc structure, and comparing model predictions of electrical propagation with experimental measures of conduction velocity, we reveal that atrial intercalated discs can support faster conduction than their ventricular counterparts, which is normally masked by interchamber differences in myocyte geometry. Further, we identify key ultrastructural and molecular organization features underpinning the ability of atrial intercalated discs to support faster conduction.

CONCLUSIONS

These data provide the first stepping stone to elucidating chamber-specific effects of pathological intercalated disc remodeling, as occurs in many arrhythmic diseases.

Extracellular Perinexal Separation Is a Principal Determinant of Cardiac Conduction

BACKGROUND

Cardiac conduction is understood to occur through gap junctions. Recent evidence supports ephaptic coupling as another mechanism of electrical communication in the heart. Conduction via gap junctions predicts a direct relationship between conduction velocity (CV) and bulk extracellular resistance. By contrast, ephaptic theory is premised on the existence of a biphasic relationship between CV and the volume of specialized extracellular clefts within intercalated discs such as the perinexus. Our objective was to determine the relationship between ventricular CV and structural changes to micro- and nanoscale extracellular spaces.

METHODS

Conduction and Cx43 (connexin43) protein expression were quantified from optically mapped guinea pig whole-heart preparations perfused with the osmotic agents albumin, mannitol, dextran 70 kDa, or dextran 2 MDa. Peak sodium current was quantified in isolated guinea pig ventricular myocytes. Extracellular resistance was quantified by impedance spectroscopy. Intercellular communication was assessed in a heterologous expression system with fluorescence recovery after photobleaching. Perinexal width was quantified from transmission electron micrographs.

RESULTS

CV primarily in the transverse direction of propagation was significantly reduced by mannitol and increased by albumin and both dextrans. The combination of albumin and dextran 70 kDa decreased CV relative to albumin alone. Extracellular resistance was reduced by mannitol, unchanged by albumin, and increased by both dextrans. Cx43 expression and conductance and peak sodium currents were not significantly altered by the osmotic agents. In response to osmotic agents, perinexal width, in order of narrowest to widest, was albumin with dextran 70 kDa; albumin or dextran 2 MDa; dextran 70 kDa or no osmotic agent, and mannitol. When compared in the same order, CV was biphasically related to perinexal width.

CONCLUSIONS

Cardiac conduction does not correlate with extracellular resistance but is biphasically related to perinexal separation, providing evidence that the relationship between CV and extracellular volume is determined by ephaptic mechanisms under conditions of normal gap junctional coupling.

Unraveling Chamber-specific Differences in Intercalated Disc Ultrastructure and Molecular Organization and Their Impact on Cardiac Conduction

During each heartbeat, the propagation of action potentials through the heart coordinates the contraction of billions of individual cardiomyocytes and is thus, a critical life process. Unsurprisingly, intercalated discs, which are cell-cell contact sites specialized to provide electrical and mechanical coupling between adjacent cardiomyocytes, have been the focus of much investigation. Slowed or disrupted propagation leads to potentially life-threatening arrhythmias in a wide range of pathologies, where intercalated disc remodeling is a common finding. Hence, the importance and urgency of understanding intercalated disc structure and its influence on action potential propagation. Surprisingly, however, conventional modeling approaches cannot predict changes in propagation elicited by perturbations that alter intercalated disc ultrastructure or molecular organization, owing to lack of quantitative structural data at subcellular through nano scales. In order to address this critical gap in knowledge, we sought to quantify intercalated disc structure at these finer spatial scales in the healthy adult mouse heart and relate them to function in a chamber-specific manner as a precursor to understanding the impacts of pathological intercalated disc remodeling. Using super-resolution light microscopy, electron microscopy, and computational image analysis, we provide here the first ever systematic, multiscale quantification of intercalated disc ultrastructure and molecular organization. By incorporating these data into a rule-based model of cardiac tissue with realistic intercalated disc structure, and comparing model predictions of electrical propagation with experimental measures of conduction velocity, we reveal that atrial intercalated discs can support faster conduction than their ventricular counterparts, which is normally masked by inter-chamber differences in myocyte geometry. Further, we identify key ultrastructural and molecular organization features underpinning the ability of atrial intercalated discs to support faster conduction. These data provide the first stepping stone to elucidating chamber-specific impacts of pathological intercalated disc remodeling, as occurs in many arrhythmic diseases.

Cell-To-Cell Communication in the Resistance Vasculature

The arterial vasculature can be divided into large conduit arteries, intermediate contractile arteries, resistance arteries, arterioles, and capillaries. Resistance arteries and arterioles primarily function to control systemic blood pressure. The resistance arteries are composed of a layer of endothelial cells oriented parallel to the direction of blood flow, which are separated by a matrix layer termed the internal elastic lamina from several layers of smooth muscle cells oriented perpendicular to the direction of blood flow. Cells within the vessel walls communicate in a homocellular and heterocellular fashion to govern luminal diameter, arterial resistance, and blood pressure. At rest, potassium currents govern the basal state of endothelial and smooth muscle cells. Multiple stimuli can elicit rises in intracellular calcium levels in either endothelial cells or smooth muscle cells, sourced from intracellular stores such as the endoplasmic reticulum or the extracellular space. In general, activation of endothelial cells results in the production of a vasodilatory signal, usually in the form of nitric oxide or endothelial-derived hyperpolarization. Conversely, activation of smooth muscle cells results in a vasoconstriction response through smooth muscle cell contraction. © 2022 American Physiological Society. Compr Physiol 12: 1-35, 2022.

Re-evaluating methods reporting practices to improve reproducibility: an analysis of methodological rigor for the Langendorff whole-heart technique

In recent decades, the scientific community has seen an increased interest in rigor and reproducibility. In 2017, concerns of methodological thoroughness and reporting practices were implicated as significant barriers to reproducibility within the preclinical cardiovascular literature, particularly in studies employing animal research. The Langendorff, whole-heart technique has proven to be an invaluable research tool, being modified in a myriad of ways to probe questions across the spectrum of physio- and pathophysiologic function of the heart. As a result, significant variability in the application of the Langendorff technique exists. This literature review quantifies the different methods employed in the implementation of the Langendorff technique and provides brief examples of how individual parametric differences can impact the outcomes and interpretation of studies. From 2017-2020, significant variability of animal models, anesthesia, cannulation time, and perfusate composition, pH, and temperature demonstrate that the technique has diversified to meet new challenges and answer different scientific questions. The review also reveals which individual methods are most frequently reported, even if there is no explicit agreement upon which parameters should be reported. The analysis of methods related to the Langendorff technique suggests a framework for considering methodological approach when interpreting seemingly contradictory results, rather than concluding that results are irreproducible.

Hypernatremia and intercalated disc edema synergistically exacerbate long-QT syndrome type 3 phenotype

Cardiac voltage-gated sodium channel gain-of-function prolongs repolarization in the long-QT syndrome type 3 (LQT3). Previous studies suggest that narrowing the perinexus within the intercalated disc, leading to rapid sodium depletion, attenuates LQT3-associated action potential duration (APD) prolongation. However, it remains unknown whether extracellular sodium concentration modulates APD prolongation during sodium channel gain-of-function. We hypothesized that elevated extracellular sodium concentration and widened perinexus synergistically prolong APD in LQT3. LQT3 was induced with sea anemone toxin (ATXII) in Langendorff-perfused guinea pig hearts (n = 34). Sodium concentration was increased from 145 to 160 mM. Perinexal expansion was induced with mannitol or the sodium channel β1-subunit adhesion domain antagonist (βadp1). Epicardial ventricular action potentials were optically mapped. Individual and combined effects of varying clefts and sodium concentrations were simulated in a computational model. With ATXII, both mannitol and βadp1 significantly widened the perinexus and prolonged APD, respectively. The elevated sodium concentration alone significantly prolonged APD as well. Importantly, the combination of elevated sodium concentration and perinexal widening synergistically prolonged APD. Computational modeling results were consistent with animal experiments. Concurrently elevating extracellular sodium and increasing intercalated disc edema prolongs repolarization more than the individual interventions alone in LQT3. This synergistic effect suggests an important clinical implication that hypernatremia in the presence of cardiac edema can markedly increase LQT3-associated APD prolongation. Therefore, to our knowledge, this is the first study to provide evidence of a tractable and effective strategy to mitigate LQT3 phenotype by means of managing sodium levels and preventing cardiac edema in patients.NEW & NOTEWORTHY This is the first study to demonstrate that the long-QT syndrome type 3 (LQT3) phenotype can be exacerbated or concealed by regulating extracellular sodium concentrations and/or the intercalated disc separation. The animal experiments and computational modeling in the current study reveal a critically important clinical implication: sodium dysregulation in the presence of edema within the intercalated disc can markedly increase the risk of arrhythmia in LQT3. These findings strongly suggest that maintaining extracellular sodium within normal physiological limits may be an effective and inexpensive therapeutic option for patients with congenital or acquired sodium channel gain-of-function diseases.

Mechanisms of Connexin Regulating Peptides

Gap junctions (GJ) and connexins play integral roles in cellular physiology and have been found to be involved in multiple pathophysiological states from cancer to cardiovascular disease. Studies over the last 60 years have demonstrated the utility of altering GJ signaling pathways in experimental models, which has led to them being attractive targets for therapeutic intervention. A number of different mechanisms have been proposed to regulate GJ signaling, including channel blocking, enhancing channel open state, and disrupting protein-protein interactions. The primary mechanism for this has been through the design of numerous peptides as therapeutics, that are either currently in early development or are in various stages of clinical trials. Despite over 25 years of research into connexin targeting peptides, the overall mechanisms of action are still poorly understood. In this overview, we discuss published connexin targeting peptides, their reported mechanisms of action, and the potential for these molecules in the treatment of disease.

The conduction velocity-potassium relationship in the heart is modulated by sodium and calcium

The relationship between cardiac conduction velocity (CV) and extracellular potassium (K⁺) is biphasic, with modest hyperkalemia increasing CV and severe hyperkalemia slowing CV. Recent studies from our group suggest that elevating extracellular sodium (Na⁺) and calcium (Ca²⁺) can enhance CV by an extracellular pathway parallel to gap junctional coupling (GJC) called ephaptic coupling that can occur in the gap junction adjacent perinexus. However, it remains unknown whether these same interventions modulate CV as a function of K⁺. We hypothesize that Na⁺, Ca²⁺, and GJC can attenuate conduction slowing consequent to severe hyperkalemia. Elevating Ca²⁺ from 1.25 to 2.00 mM significantly narrowed perinexal width measured by transmission electron microscopy. Optically mapped, Langendorff-perfused guinea pig hearts perfused with increasing K⁺ revealed the expected biphasic CV-K⁺ relationship during perfusion with different Na⁺ and Ca²⁺ concentrations. Neither elevating Na⁺ nor Ca²⁺ alone consistently modulated the positive slope of CV-K⁺ or conduction slowing at 10-mM K⁺; however, combined Na⁺ and Ca²⁺ elevation significantly mitigated conduction slowing at 10-mM K⁺. Pharmacologic GJC inhibition with 30-μM carbenoxolone slowed CV without changing the shape of CV-K⁺ curves. A computational model of CV predicted that elevating Na⁺ and narrowing clefts between myocytes, as occur with perinexal narrowing, reduces the positive and negative slopes of the CV-K⁺ relationship but do not support a primary role of GJC or sodium channel conductance. These data demonstrate that combinatorial effects of Na⁺ and Ca²⁺ differentially modulate conduction during hyperkalemia, and enhancing determinants of ephaptic coupling may attenuate conduction changes in a variety of physiologic conditions.

Elevated perfusate [Na+] increases contractile dysfunction during ischemia and reperfusion

Recent studies revealed that relatively small changes in perfusate sodium ([Na⁺]_o) composition significantly affect cardiac electrical conduction and stability in contraction arrested ex vivo Langendorff heart preparations before and during simulated ischemia. Additionally, [Na⁺]_o modulates cardiomyocyte contractility via a sodium-calcium exchanger (NCX) mediated pathway. It remains unknown, however, whether modest changes to [Na⁺]_o that promote electrophysiologic stability similarly improve mechanical function during baseline and ischemia-reperfusion conditions. The purpose of this study was to quantify cardiac mechanical function during ischemia-reperfusion with perfusates containing 145 or 155 mM Na⁺ in Langendorff perfused isolated rat heart preparations. Relative to 145 mM Na⁺, perfusion with 155 mM [Na⁺]_o decreased the amplitude of left-ventricular developed pressure (LVDP) at baseline and accelerated the onset of ischemic contracture. Inhibiting NCX with SEA0400 abolished LVDP depression caused by increasing [Na⁺]_o at baseline and reduced the time to peak ischemic contracture. Ischemia-reperfusion decreased LVDP in all hearts with return of intrinsic activity, and reperfusion with 155 mM [Na⁺]_o further depressed mechanical function. In summary, elevating [Na⁺]_o by as little as 10 mM can significantly modulate mechanical function under baseline conditions, as well as during ischemia and reperfusion. Importantly, clinical use of Normal Saline, which contains 155 mM [Na⁺]_o, with cardiac ischemia may require further investigation.

Abstract MP114: Cardiotropic Adenovirus Increases Arrhythmia Susceptibility During Acute Infection

Myocarditis is responsible for up to 42% of sudden cardiac death in young adults yet mechanisms underlying virally-induced arrhythmia remain elusive. Adenovirus is a leading etiological agent of myocarditis but due to species-specificity, in vivo models are limited. Altered cardiac gap junction function underlies sudden cardiac death and given that gap junctions also propagate antiviral immune responses, we hypothesized adenovirus would target intercellular coupling, leading to arrhythmogenesis. Employing a recently described strain of mouse adenovirus, MAdV-3, we investigated cardiotropism, arrhythmia susceptibility, and molecular mechanisms of a virally-induced arrhythmogenic substrate. Adult C57BL/6 mice were inoculated with MAdV-3 and infection allowed to progress for one week. Viral genomes were detected by qPCR to measure tissue tropism together with whole animal histopathology. Echo- and electrocardiography were used to measure cardiac function and electrical activity. Viral effects on transcription and junctional protein/ion channel expression and localization were quantified using RT-qPCR, confocal microscopy, and western blotting. Finally, ex vivo optical mapping was employed to test conduction defects and susceptibility to arrhythmia. We find MAdV-3 viral genomes specifically enriched in heart tissue, confirming cardiotropism. Immune cell infiltration was not detected in the heart and no cardiomyopathy was apparent by echocardiography. RR interval widening, however, does occur in MAdV-3 infected mice with reductions in cardiac ion channel and gap junction mRNA transcripts. Optical mapping experiments show that conduction velocity is altered in acutely infected hearts and norepinephrine challenge uncovered electrical impairment presenting as atrioventricular dissociation with increased premature ventricular contraction burden. Our data demonstrate that MAdV-3 is cardiotropic and acute infection result in changes in cardiac electrical activity prior to development of cardiomyopathy or a detectable immune response. MAdV-3 infection is a novel model for adenoviral myocarditis, providing insights into viral subversion of cardiac intercellular coupling and mechanisms of arrhythmogenesis.

Modulating cardiac conduction during metabolic ischemia with perfusate sodium and calcium in guinea pig hearts

We previously demonstrated that altering extracellular sodium (Na_o) and calcium (Ca_o) can modulate a form of electrical communication between cardiomyocytes termed "ephaptic coupling" (EpC), especially during loss of gap junction coupling. We hypothesized that altering Na_o and Ca_o modulates conduction velocity (CV) and arrhythmic burden during ischemia. Electrophysiology was quantified by optically mapping Langendorff-perfused guinea pig ventricles with modified Na_o (147 or 155 mM) and Ca_o (1.25 or 2.0 mM) during 30 min of simulated metabolic ischemia (pH 6.5, anoxia, aglycemia). Gap junction-adjacent perinexal width ( W_P), a candidate cardiac ephapse, and connexin (Cx)43 protein expression and Cx43 phosphorylation at S368 were quantified by transmission electron microscopy and Western immunoblot analysis, respectively. Metabolic ischemia slowed CV in hearts perfused with 147 mM Na_o and 2.0 mM Ca_o; however, theoretically increasing EpC with 155 mM Na_o was arrhythmogenic, and CV could not be measured. Reducing Ca_o to 1.25 mM expanded W_P, as expected during ischemia, consistent with reduced EpC, but attenuated CV slowing while delaying arrhythmia onset. These results were further supported by osmotically reducing W_P with albumin, which exacerbated CV slowing and increased early arrhythmias during ischemia, whereas mannitol expanded W_P, permitted conduction, and delayed the onset of arrhythmias. Cx43 expression patterns during the various interventions insufficiently correlated with observed CV changes and arrhythmic burden. In conclusion, decreasing perfusate calcium during metabolic ischemia enhances perinexal expansion, attenuates conduction slowing, and delays arrhythmias. Thus, perinexal expansion may be cardioprotective during metabolic ischemia. NEW & NOTEWORTHY This study demonstrates, for the first time, that modulating perfusate ion composition can alter cardiac electrophysiology during simulated metabolic ischemia.

Electromechanical Model to Predict Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) can substantially improve dyssynchronous heart failure and reduce mortality. However, one-third of the CRT patients derive no measurable benefit from CRT, due to suboptimal placement of the left ventricular (LV) lead. We introduce a pipeline for improved CRT-therapy by creating an electromechanical model using patient-specific geometric parameters allowing individualization of therapy. The model successfully mimics expected changes when variables for tension, stiffness, and conduction are entered. Changing LV pacing site had a notable effect on maximum pressure gradient (dP/dt_max) in the presence of cardiac scarring, causing non-uniform excitation propagation through the LV. Tailoring CRT to the individual requires simulations with patient-specific biventricular meshes including cardiac geometry and conductivity properties.

The adhesion function of the sodium channel beta subunit (β1) contributes to cardiac action potential propagation

Computational modeling indicates that cardiac conduction may involve ephaptic coupling – intercellular communication involving electrochemical signaling across narrow extracellular clefts between cardiomyocytes. We hypothesized that β1(SCN1B) –mediated adhesion scaffolds trans-activating Na_V1.5 (SCN5A) channels within narrow (<30 nm) perinexal clefts adjacent to gap junctions (GJs), facilitating ephaptic coupling. Super-resolution imaging indicated preferential β1 localization at the perinexus, where it co-locates with Na_V1.5. Smart patch clamp (SPC) indicated greater sodium current density (I_Na) at perinexi, relative to non-junctional sites. A novel, rationally designed peptide, βadp1, potently and selectively inhibited β1-mediated adhesion, in electric cell-substrate impedance sensing studies. βadp1 significantly widened perinexi in guinea pig ventricles, and selectively reduced perinexal I_Na, but not whole cell I_Na, in myocyte monolayers. In optical mapping studies, βadp1 precipitated arrhythmogenic conduction slowing. In summary, β1-mediated adhesion at the perinexus facilitates action potential propagation between cardiomyocytes, and may represent a novel target for anti-arrhythmic therapies.

Intercalated Disk Extracellular Nanodomain Expansion in Patients With Atrial Fibrillation

Aims: Atrial fibrillation (AF) is the most common sustained arrhythmia. Previous evidence in animal models suggests that the gap junction (GJ) adjacent nanodomain – perinexus – is a site capable of independent intercellular communication via ephaptic transmission. Perinexal expansion is associated with slowed conduction and increased ventricular arrhythmias in animal models, but has not been studied in human tissue. The purpose of this study was to characterize the perinexus in humans and determine if perinexal expansion associates with AF.

Methods: Atrial appendages from 39 patients (pts) undergoing cardiac surgery were fixed for immunofluorescence and transmission electron microscopy (TEM). Intercalated disk distribution of the cardiac sodium channel Nav1.5, its β1 subunit, and connexin43 (C×43) was determined by confocal immunofluorescence. Perinexal width (Wp) from TEM was manually segmented by two blinded observers using ImageJ software.

Results: Nav1.5, β1, and C×43 are co-adjacent within intercalated disks of human atria, consistent with perinexal protein distributions in ventricular tissue of other species. TEM revealed that the GJ adjacent intermembrane separation in an individual perinexus does not change at distances greater than 30 nm from the GJ edge. Importantly, Wp is significantly wider in patients with a history of AF than in patients with no history of AF by approximately 3 nm, and Wp correlates with age (R = 0.7, p < 0.05).

Conclusion: Human atrial myocytes have voltage-gated sodium channels in a dynamic intercellular cleft adjacent to GJs that is consistent with previous descriptions of the perinexus. Further, perinexal width is greater in patients with AF undergoing cardiac surgery than in those without.

Design and validation of a tissue bath 3-D printed with PLA for optically mapping suspended whole heart preparations

With the sudden increase in affordable manufacturing technologies, the relationship between experimentalists and the designing process for laboratory equipment is rapidly changing. While experimentalists are still dependent on engineers and manufacturers for precision electrical, mechanical, and optical equipment, it has become a realistic option for in house manufacturing of other laboratory equipment with less precise design requirements. This is possible due to decreasing costs and increasing functionality of desktop three-dimensional (3-D) printers and 3-D design software. With traditional manufacturing methods, iterative design processes are expensive and time consuming, and making more than one copy of a custom piece of equipment is prohibitive. Here, we provide an overview to design a tissue bath and stabilizer for a customizable, suspended, whole heart optical mapping apparatus that can be produced significantly faster and less expensive than conventional manufacturing techniques. This was accomplished through a series of design steps to prevent fluid leakage in the areas where the optical imaging glass was attached to the 3-D printed bath. A combination of an acetone dip along with adhesive was found to create a water tight bath. Optical mapping was used to quantify cardiac conduction velocity and action potential duration to compare 3-D printed baths to a bath that was designed and manufactured in a machine shop. Importantly, the manufacturing method did not significantly affect conduction, action potential duration, or contraction, suggesting that 3-D printed baths are equally effective for optical mapping experiments.NEW & NOTEWORTHY This article details three-dimensional printable equipment for use in suspended whole heart optical mapping experiments. This equipment is less expensive than conventional manufactured equipment as well as easily customizable to the experimentalist. The baths can be waterproofed using only a three-dimensional printer, acetone, a glass microscope slide, c-clamps, and adhesive.

Trauma team utilization of universal precautions: if you see something, say something

PURPOSE

The risks deriving from the lack of compliance with universal safety precautions (USPs) are unequivocal. However, the adoption of these prophylactic precautions by healthcare providers remains unacceptably low. We hypothesized that trauma teams are not routinely adhering to USPs and that a brief educational intervention, followed by real-time peer feedback, would substantially improve compliance rates.

METHODS

This before-and-after interventional study took place in the resuscitation bay of a Level I Trauma Center during trauma team activations. Six USPs were examined: hand washing (before and after patient contact), use of gloves, gowns, eye protection, and masks. Surgery and Emergency Medicine attending physicians, residents, and nurses, who had direct patient contact, were included. Following 162 baseline observations, an educational intervention in the form of brief lectures was conducted, emphasizing the danger to self from dereliction of USPs. Subsequently, 167 post-intervention observations were made after a one-month period of knowledge decay. Finally, real-time feedback was provided by trauma team leaders and study staff. Adherence to prophylactic measures was recorded again.

RESULTS

Baseline compliance rates were dismal. Only hand washing prior to patient interaction, the use of eye protection, and the use of masks improved significantly (p < 0.05) after the educational initiative. However, compliance rates remained suboptimal. No difference was noted regarding the three other USPs. Impressively, following real-time behavioral corrections, compliance improved to nearly 90 % for all USPs (p < 0.05).

CONCLUSIONS

Compliance with OSHA-required USPs during trauma team activations is unacceptably low, but can be dramatically improved through simple educational interventions, combined with real-time peer feedback.

Esophageal ileus following laparoscopic fundoplication

Early postoperative dysphagia occurs in most patients following laparoscopic fundoplication. Whether dysphagia is associated with a change in esophageal motor function and/or a change in gastroesophageal junction characteristics is unknown. Esophageal motility in the early postoperative period has not been evaluated previously. Esophageal motility was studied on the first postoperative day in 10 patients who underwent laparoscopic Nissen fundoplication and 10 patients who underwent laparoscopic cholecystectomy (control group), using standard perfusion manometry. Primary peristalsis on water swallows following fundoplication elicted a median response of 5% successful peristalsis compared with median response of 100% successful peristalsis following cholecystectomy (P = 0.05). The fundoplication was associated with failure of primary esophageal peristalsis in 7/10 patients, compared to 2/10 patients who underwent cholecystectomy (P = 0.068 Fisher's exact test). Three months after fundoplication, in nine patients studied, primary peristalsis was similar to peristalsis observed preoperatively in seven patients and two patients still had an aperistaltic esophagus. In this study, esophageal manometry 1 day after surgery demonstrated grossly disturbed esophageal motility in most patents following laparoscopic fundoplication, compared to normal motility following laparoscopic cholecystectomy. Peristalsis improved at 3 months or more following surgery. This suggests that an 'esophageal ileus' occurs during the early period after laparoscopic fundoplication.

Measuring asthma control. Clinic questionnaire or daily diary?

Daily symptom, peak expiratory flow rate (PEFR), and medication diaries are often used in clinical trials of treatments for asthma on the assumption that they provide a better estimate of clinical status than does a questionnaire completed in the clinic. We conducted a study with the aim of comparing the measurement properties of the clinic-completed Asthma Control Questionnaire with those of the Asthma Control Diary. The diary is composed of questions and response options almost identical to those of the questionnaire, but uses PEFR instead of FEV(1) as the measure of airway caliber. In an observational study, 50 adults with symptomatic asthma attended a McMaster University asthma clinic at 0, 1, 5, and 9 wk to complete the Asthma Control Questionnaire and other measures of asthma status. For 1 wk before each follow-up visit, patients completed the Asthma Control Diary every morning and evening. Concordance between the questionnaire and diary was high (intraclass correlation coefficient [ICC] = 0.87). Both reliability (ICC: questionnaire = 0.90; diary = 0.86) and responsiveness (responsiveness index: questionnaire = 1.06; diary = 0.90; p = 0.005) were better with the questionnaire than with the diary. Correlations between the two instruments and other measures of clinical asthma status were similar and close to a priori predictions. Both the Asthma Control Questionnaire and the Asthma Control Diary are valid instruments for measuring asthma control, but the questionnaire has slightly better discriminative and evaluative measurement properties than does the diary.

Randomized comparison of cisplatin/vincristine/fluorouracil and cisplatin/continuous infusion doxorubicin for treatment of pediatric hepatoblastoma: A report from the Children's Cancer Group and the Pediatric Oncology Group

PURPOSE

Previous studies demonstrated that chemotherapy with either cisplatin, vincristine, and fluorouracil (regimen A) or cisplatin and continuous infusion doxorubicin (regimen B) improved survival in children with hepatoblastoma. The current trial is a randomized comparison of these two regimens.

PATIENTS AND METHODS

Patients (N = 182) were enrolled onto study between August 1989 and December 1992. After initial surgery, patients with stage I-unfavorable histology (UH; n = 43), stage II (n = 7), stage III (n = 83), and stage IV (n = 40) hepatoblastoma were randomized to receive regimen A (n = 92) or regimen B (n = 81). Patients with stage I-favorable histology (FH; n = 9) were treated with four cycles of doxorubicin alone.

RESULTS

There were no events among patients with stage I-FH disease. Five-year event-free survival (EFS) estimates were 57% (SD = 5%) and 69% (SD = 5%) for patients on regimens A and B, respectively (P =.09) with a relative risk of 1.54 (95% confidence interval, 0.93 to 2.5) for regimen A versus B. Toxicities were more frequent on regimen B. Patients with stage I-UH, stage II, stage III, or stage IV disease had 5-year EFS estimates of 91% (SD = 4%), 100%, 64% (SD = 5%), and 25% (SD = 7%), respectively. Outcome was similar for either regimen within disease stages. At postinduction surgery I, patients with stage III or IV disease who were found to be tumor-free had no events; those who had complete resections achieved a 5-year EFS of 83% (SD = 6%); other patients with stage III or IV disease had worse outcome.

CONCLUSION

Treatment outcome was not significantly different between regimen A and regimen B. Excellent outcome was achieved for patients with stage I-UH and stage II hepatoblastoma and for subsets of patients with stage III disease. New treatment strategies are needed for the majority of patients with advanced-stage hepatoblastoma.

A cost-effective thoracoscopic treatment strategy for pediatric spontaneous pneumothorax

BACKGROUND

Recent data suggest that children have a higher incidence of recurrence than adults after nonoperative treatment of primary spontaneous pneumothorax (PSP). Video-assisted thoracoscopic surgery (VATS) allows efficacious therapy with significantly less morbidity. We attempt to define the most cost-effective clinically efficacious strategy using VATS to manage pediatric PSP.

METHODS

We retrospectively reviewed all admissions to a tertiary care children's hospital for PSP between January 1, 1991 and June 30, 1996.

RESULTS

Fifteen children had 29 primary or recurrent PSPs. Mean patient age was 14.8 +/- 1.1 years, boy-girl ratio 4:1, median body mass index 18 (normal, 20-25), and 67% of pneumothoraces left sided. All patients were managed initially nonoperatively: 14 with tube thoracostomy drainage and 1 with oxygen alone. Of the children initially managed nonoperatively, 57% had a recurrent pneumothorax, and 50% of these patients eventually developed contralateral pneumothoraces. Nonoperative treatment for recurrence resulted in a 75% second recurrence rate. In contrast, eight children who underwent operative management had a 9% incidence of recurrence. The total for charges accrued in treating 29 pneumothoraces in these 15 patients was approximately $315,000. In the same population, the estimated charges for initial nonoperative therapy followed by bilateral thoracoscopy after a single recurrence would be $230,000.

CONCLUSIONS

A cost-effective treatment strategy for pediatric primary spontaneous pneumothorax is tube thoracostomy at first presentation, followed by VATS with thoracoscopic bleb resection and pleurodesis for patients who experience recurrent pneumothorax.

Development and validation of a questionnaire to measure asthma control

International guidelines on asthma management indicate that the primary goal of treatment should be optimum asthma control. The aim of this study was to develop and validate the Asthma Control Questionnaire (ACQ). The authors generated a list of all symptoms used to assess control and sent it to 100 asthma clinicians who were members of guidelines committees (18 countries). They scored each symptom for its importance in evaluating asthma control. From the 91 responses, the five highest scoring symptoms were selected for the ACQ. In addition, there is one question on beta2-agonist use and another on airway calibre (total questions=7). The ACQ was tested in a 9-week observational study of 50 adults with symptomatic asthma. The ACQ and other measures of asthma health status were assessed at baseline, 1, 5 and 9 weeks. In patients whose asthma was stable between clinic visits, reliability of the ACQ was high (intraclass correlation coefficient (ICC)=0.90). The questionnaire was very responsive to change in asthma control (p<0.0001). Cross-sectional and longitudinal validity were supported by correlations between the ACQ and other measures of asthma health status being close to a priori predictions. In conclusion, the Asthma Control Questionnaire has strong evaluative and discriminative properties and can be used with confidence to measure asthma control.

Development and validation of the Mini Asthma Quality of Life Questionnaire

The 32-item Asthma Quality of Life Questionnaire (AQLQ) has shown good responsiveness, reliability and construct validity; properties that are essential for use in clinical trials, clinical practice and surveys. However, to meet the needs of large clinical trials and long-term monitoring, where efficiency may take precedent over precision of measurement, the 15-item self-administered MiniAQLQ has been developed. The MiniAQLQ was tested in a 9-week observational study of 40 adults with symptomatic asthma. Patients completed the MiniAQLQ, the AQLQ, the Short Form (SF)-36, the Asthma Control Questionnaire and spirometry at baseline, 1, 5 and 9 weeks. In patients whose asthma was stable between clinic visits, reliability was very acceptable for the MiniAQLQ (intraclass correlation coefficient (ICC)=0.83), but not quite as good as for the AQLQ (ICC=0.95). Similarly, responsiveness in the MiniAQLQ (p=0.0007) was good but not quite so good as for the AQLQ (p<0.0001). Construct validity (correlation with other indices of health status) was strong for both the MiniAQLQ and the AQLQ. Criterion validity showed that there was no bias between the instruments (p=0.61) and the correlation between them was high (r=0.90). The Mini Asthma Quality of Life Questionnaire has good measurement properties but they are not quite as strong as those of the original Asthma Quality of Life Questionnaire. The choice of questionnaire should depend on the task at hand.

Validation of a standardized version of the Asthma Quality of Life Questionnaire

BACKGROUND

In the original 32-item Asthma Quality of Life Questionnaire (AQLQ), five activity questions are selected by patients themselves. However, for long-term studies and large clinical trials, generic activities may be more appropriate.

METHODS

For the standardized version of the AQLQ, the AQLQ(S), we formulated five generic activities (strenuous exercise, moderate exercise, work-related activities, social activities, and sleep) to replace the five patient-specific activities in the AQLQ. In a 9-week observational study, we compared the AQLQ with the AQLQ(S) and examined their measurement properties. Forty symptomatic adult asthma patients completed the AQLQ(S), the AQLQ, the Medical Outcomes Survey Short Form 36, the Asthma Control Questionnaire, and spirometry at baseline, 1, 5, and 9 weeks.

RESULTS

Activity domain scores (mean +/- SD) were lower with the AQLQ (5.7 +/- 0.9) than with the AQLQ(S) (5.9 +/- 0.8; p = 0.0003) and correlation between the two was moderate (r = 0.77). However, for overall scores, there was minimal difference (AQLQ, 5.4 +/- 0.8; AQLQ(S), 5.5 +/- 0.8; r = 0.99). Reliability (AQLQ intraclass correlation coefficient, 0.95; AQLQ(S) intraclass correlation coefficient, 0.96) and responsiveness (AQLQ, p < 0.0001; AQLQ(S), p < 0.0001) were similar for the two instruments. Construct validity (correlation with other measures of health status and clinical asthma) was also similar for the two instruments.

CONCLUSIONS

The AQLQ(S) has strong measurement properties and is valid for measuring health-related quality of life in asthma. The choice of instrument should depend on the task at hand.

Generic and specific measurement of health-related quality of life in a clinical trial of respiratory rehabilitation

The purpose of this study was to compare the performance of measures of health-related quality of life in a randomized controlled trial of respiratory rehabilitation versus conventional community care for patients with chronic airflow limitation. The study included 89 stable patients with moderate to severe chronic airflow limitation with measurement of health status at 12, 18, and 24 weeks. Outcomes included two disease-specific (the Oxygen Cost Diagram and the Chronic Respiratory Questionnaire [CRQ]) measures, a generic health profile (the Sickness Impact Profile [SIP]), and two utility measures (the Standard Gamble and the Quality of Well-Being index [QWB]). Of the measures, only the four domains of the CRQ (dyspnea, fatigue, mastery, and emotional function) showed statistically significant differences (P < or = 0.05) between treatment and control groups. Correlation between change in the CRQ and change in other relevant measures, including the 6-minute walk test and global ratings of change in dyspnea, fatigue, and emotional function were generally weak to moderate (from 0.19 to 0.51). All correlations between change in the QWB, SIP, and Standard Gamble and other measures were very weak or weak (up to 0.30). Correlation between change in the three generic measures were all very weak (<0.15). The results suggest that unless investigators include responsive and valid disease-specific measures of health-related quality of life in controlled trials in chronic diseases, they risk misleading conclusions about the effect of treatments on health status.

Multiple endocrine neoplasia type 2A: a 25-year review

BACKGROUND/PURPOSE

Before 1970, treatment decisions for the thyroid lesions in patients with multiple endocrine neoplasia (MEN) were based on physical findings. For the next 20 years, biological markers assumed a preeminent role, and at present, DNA testing is being used to define the need for therapeutic intervention. This report presents a 25-year review of 22 children with MEN-2A, with a mean follow-up of 12.5 years.

METHODS

All 22 children underwent a total thyroidectomy, and four (18%) were rendered permanently hypoparathyroid. Since 1976, however, only one patient (6.7%) has lost parathyroid function. Despite the fact that biological screening studies routinely were performed once a year in the majority of our patients and surgery was recommended for any elevation in the serum calcitonin (CT) levels, medullary carcinoma of the thyroid (MTC) developed in 17 children (77%) and only five had C cell hyperplasia (CCH). Thirteen of the 17 had macroscopic tumor described by the pathologist, evidence of recurrent disease (MTC-REC) has developed in four children (24%).

RESULTS

There was considerable overlap in both the basal and stimulated CT levels among the five children with CCH, the 13 with localized MTC (MTC-NED), and the four who later had recurrent MTC. The basal calcitonin levels were between 25 and 110 (mean, 58) in the CCH patients, 30 to 1,130 (mean, 184) in the MTC-NED group, and 108 to 201 (mean, 140) in those with recurrent MTC. The corresponding stimulated calcitonin levels were 45 to 417 (mean, 179) in CCH, 111 to 9,510 (mean, 1,407) in MTC-NED, and 449 to 5,093 (mean, 3,383) in MTC-REC.

CONCLUSIONS

(1) Basal and pentagastrin-stimulated CT levels did not reliably discriminate between CCH and MTC and should not be used to define the timing of thyroid surgery in children with MEN-2A. (2) Surgical therapy should be undertaken early in childhood on the basis of molecular genetic testing. (3) Postoperative complications are infrequent in the modern era.

Aortobronchial fistula after expandable metal stent insertion for pediatric bronchomalacia

Indications for using expandable metal stents (EMS) for airway disease have expanded considerably during the past decade. Complications have been infrequent but can be potentially life threatening. There are four reported instances of vascular bronchial fistula after Gianturco EMS insertion for managing airway disease in adults. The authors report a case of an aortobronchial fistula in a pediatric patient after Palmaz EMS insertion for treatment of bronchomalacia. A 14-year-old boy with severe scoliosis underwent left mainstem bronchus insertion of two Palmaz stents in tandem for correction of complete bronchial obstruction caused by vascular compression. Three weeks later fatal hemoptysis from an aortobronchial fistula developed. Elective EMS insertion for treatment of airway obstruction secondary to compression by vascular structures should be approached with caution. EMS placement should be reserved for situations in which there is no other reasonable surgical alternative.

Measuring quality of life in children with rhinoconjunctivitis

OBJECTIVE

The objective of this study was to develop, pretest, and validate a questionnaire to measure quality of life in children with seasonal allergic rhinoconjunctivitis (SAR).

METHODS (DEVELOPMENT STUDY)

Thirty-four children with SAR were enrolled from summer camps, notices in the media, and an allergy clinic (Southern Ontario). After generating a pool of 48 potentially important quality of life items, the children identified the ones that they experienced with their SAR and scored each for bother (1 = a little bothered to 4 = extremely bothered). Items identified most frequently and with the highest bother score were included in the Paediatric Rhinoconjunctivitis Quality of Life Questionnaire (PRQLQ). The PRQLQ was pretested for ease completion and accuracy of understanding.

RESULTS (DEVELOPMENT STUDY)

The PRQLQ has 23 items in five domains (nose symptoms, eye symptoms, practical problems, other symptoms, and activities). Responses are given on a seven-point scale, and children are asked to score their experiences during the previous 7 days.

METHODS (VALIDATION STUDY)

Seventy-five children with symptomatic SAR were enrolled from notices in the media and a pediatric allergy clinic (Austin, Tex.). A single cohort design was used, with children assessed at 0, 1, and 3 weeks. The PRQLQ was administered to the children by a trained interviewer at 1 and 3 weeks. A conventional nasal symptom daily diary was completed for 1 week before each of these clinic visits. Global ratings were completed at the final visit.

RESULTS (VALIDATION STUDY)

In patients who were stable between clinic visits, the PRQLQ demonstrated good reliability (intraclass correlation coefficient = 0.93). The questionnaire was very responsive to change (p < 0.001) and was able to differentiate between patients who were in a stable clinical state and those whose clinical state changed between visits (p = 0.005). Correlations between the PRQLQ and diary scores were close to predicted and supported both the cross-sectional and longitudinal validity of the PRQLQ.

CONCLUSIONS

The PRQLQ measures the quality of life impairments important to children with SAR. Children provide reliable and accurate responses, the measurement properties are strong, and the questionnaire can be used with confidence in clinical trials, clinical practice, and surveys.

Prognostic classification for esophageal atresia and tracheoesophageal fistula: Waterston versus Montreal

Since 1962, the Waterston classification has been used to stratify neonates who have esophageal atresia (EA) and/or tracheoesophageal fistula (TEF) into prognostic categories based on birth weight, the presence of pneumonia, and the identification of other congenital anomalies. In response to advances in neonatal care, the surgeons from the Montreal Children's Hospital proposed a new categorization system in 1993 in an attempt to define the current risk factors for patients who have EA/TEF. In the Montreal experience only two characteristics independently affected survival: preoperative ventilator dependence and associated major anomalies. The goal of this study was to determine which system had the greatest validity for the evaluation of prognosis in our patients with EA/TEF. The charts of 94 patients who had EA/TEF treated between 1972 and 1991 were reviewed. Patients were classified using both the Waterston and Montreal systems. Groups were compared with Fisher's Exact test using a 95% confidence level for statistical significance. Eleven infants were ventilator dependent preoperatively; 62 children had major associated anomalies, 8 of which were considered life threatening. Sixteen children died within 4 years, eight during their initial hospital stay. Five of the eight early postoperative deaths occurred in the highest-risk patients (Waterston C or Montreal II). Analysis was performed for multiple risk factors and mortality. As in the Montreal study, the presence of life-threatening and major congenital anomalies represented significant risk factors for death. Pulmonary disease as delineated by ventilator dependence appeared to be more accurate than pneumonia. This study confirms the accuracy of the Montreal classification in defining prognosis for EA/TEF. The Montreal system more accurately identifies children at highest risk than the Waterston classification.

Timing and magnitude of decline in alpha-fetoprotein levels in treated children with unresectable or metastatic hepatoblastoma are predictors of outcome: a report from the Children's Cancer Group

PURPOSE

We analyzed data on 31 children with primary unresectable or metastatic hepatoblastoma (HB) to investigate possible prognostic correlations between the serum level of alpha-fetoprotein (AFP), its changes during treatment, and outcome.

PATIENTS AND METHODS

Patients were treated according to the Children's Cancer Group (CCG) protocol 823F, which included an initial surgery before eight courses of chemotherapy that consisted of cisplatin immediately followed by a continuous infusion of doxorubicin. Four courses were given before and four after the second surgery. AFP levels were measured before treatment, before and after second surgery, and at the end of treatment.

RESULTS

Twenty-four of 31 patients showed a decline of > or = 1 log in AFP levels before second surgery (early responders). By the end of treatment, there were 16 patients, all early responders, without clinical or radiographic evidence of tumor and with normal AFP levels. Fifteen of those 16 had a decline of > or = 2 logs in AFP before second surgery (large early response). Of the 15 patients who failed to respond to treatment, 10 died, among whom only one patient had a large early response. A large early response was the strongest independent predictor of outcome in a univariate and multivariate Cox regression model, and patients with such a response had the best survival (P < .0001).

CONCLUSION

For children with unresectable or metastatic HB, early changes in AFP levels are a reliable predictor of outcome and can be used for identification of poor responders to treatment, ie, patients whose AFP level fails to decrease 2 logs before second surgery should be considered for alternative treatment.

Clinical impact versus factor analysis for quality of life questionnaire construction

OBJECTIVE

We have compared two philosophically different methods for selecting items for a disease-specific quality of life questionnaire. The impact method selects items that are most frequently perceived as important by patients whereas the psychometric method (factor analysis) selects items primarily according to their relationships with one another.

PATIENTS

150 adults with symptomatic asthma and a wide range of disease severity were enrolled from asthma clinics and notices in the local media.

STUDY DESIGN

From a list of 152 items that are potentially troublesome to patients with asthma, the patients identified those items they had experienced in the previous year and scored the importance of each on a five-point scale. For the impact method, items that were identified most frequently and that scored the highest were included in the final instrument. For the psychometric method, factor analysis was performed after highly skewed items had been removed. Items with high factor loading were included in the final instrument.

RESULTS

The impact method resulted in a 32-item instrument and psychometric analysis in one with 36 items. Twenty items were common to both instruments. The psychometric approach discarded the highest impact emotional function and environmental items and included in their place lower impact items mainly associated with fatigue.

CONCLUSIONS

Although some items were the same for both methods, there were also some important differences. Different approaches to item reduction led to appreciably different instruments.

Pulmonary function is compromised in children with mediastinal lymphoma

PURPOSE

Lymphomas account for nearly 20% of the malignancies in childhood and the majority of patients with Hodgkin's Disease (HD) and non-Hodgkin's lymphoma (NHL) have radiological evidence of mediastinal involvement at presentation. Children with mediastinal tumors are at risk for the development of lethal airway obstruction during general anesthesia. This study quantitates the degree of the airway obstruction and the functional significance of tracheal compression in a cohort of 51 children with HD and NHL.

RESULTS

Thirty patients with HD (mean age, 14.6 years) and 21 with NHL (mean age, 9.2 years) were included in this study. Twenty-five children (49%) had respiratory symptoms at the time of presentation. Respiratory complaints were much more common in children with NHL (76%) when compared with those with HD (30%). Pulmonary function was also significantly worse in the NHL patients who had a mean upright forced vital capacity (FVC) of 66 +/- 21%. The comparable value for the children with HD was 85 +/- 15% (P = .031). Patients with respiratory symptoms at presentation had both obstructive and restrictive deficits of pulmonary function. Their mean upright forced expiratory volume in 1 second (FEV1) was 69 +/- 22% and the FVC was 69 +/- 18%. Children with large mediastinal masses also had significantly decreased pulmonary function compared with those with small tumors. The upright FEV1 for these two groups was 72 +/- 18% versus 98 +/- 15% (P = .016). Their FVC values were 68 +/- 20% and 91 +/- 17%, respectively (P = .049). Mean tracheal compression was measured at 44% in the children with large tumors versus 27% for those with small lesions (P = .048).

CONCLUSION

Children with mediastinal lymphomas have both obstructive and restrictive deficits on pulmonary function testing. Pulmonary function is significantly decreased in patients with NHL, children who present with respiratory symptoms, and those with very large mediastinal masses (mediastinal mass ratio > 45%). The extent of tracheal compression correlates with the size of the mediastinal mass.

The Efficacy of Finlayson Troughs as a Means of Repelling Kangaroos From Water and Altering Grazing Pressure in Pastoral Areas

We attempted to determine whether Finlayson troughs (a selective electric repellent device) would repel kangaroos (Macropus rufus and M. robustus) but still allow sheep to drink when access of kangaroos to artificial water sources was restricted on a large scale, and the effect that had on kangaroo populations. In late 1993 high percentages of kangaroos (over 80% of both species) were repelled from water sources fitted with Finlayson troughs when alternative water sources were available. However, when all water sources within a 100,000 ha area had activated Finlayson troughs or were fenced off, kangaroos found methods that enabled them to circumvent the Finlayson troughs within two weeks after activation of the troughs. The numbers which were able to obtain a drink increased greatly over this period. When used on a large scale, Finlayson troughs as used in this study were thus apparently ineffective in restricting the access of kangaroos to water. Aerial surveys and radio-tracking were used to determine the numbers and distribution of kangaroos over the whole area after activation of all the Finlayson troughs. There were no significant differences in kangaroo numbers between the treated area and a nearby control area which was devoid of Finlayson troughs. All 31 of the radio-collared kangaroos which could be located at the end of the trial remained within the areas they formerly occupied and the length of their movements did not increase.

Intrathoracic cystic hygroma: a report of three cases

Cystic hygromas are relatively uncommon benign tumors of the lymphatic system. The lesions frequently are apparent at birth, and more than 90% are detected before the end of the second year of life. Most commonly, cystic hygroma presents as a soft tissue mass in the posterior triangle of the neck, and only rarely does it extend into the mediastinum. Isolated intrathoracic hygromas are exceedingly rare and have been reported infrequently among children. Herein the authors review three cases of intrathoracic cystic hygroma, spanning a period of 30 years at their institution.

Does the colon adopt small bowel features in a small bowel environment?

BACKGROUND

Isoperistaltic colon interposition is one of several surgical options available in the treatment of short bowel syndrome. It functions primarily by slowing the rapid intestinal transit that follows small bowel resection (SBR). Previous studies have interposed distal colonic segments and although there is evidence of adaptation by the interposed colon it is not known whether these segments develop histologic or functional small bowel characteristics.

METHODS

In this study evidence was sought of metaplasia in the interposed segments after 80% SBR and, because proximal colon is a midgut derivative, the differences between proximal and distal colonic segments were examined.

RESULTS

There was no qualitative histological evidence of metaplasia by the interposed segments. There was a significant increase in crypt depth, mucosal thickness and maltase concentration of the interposed segments compared with the nontransposed colon of the controls. The maltase concentations were increased to the extent that they were not significantly different from the concentration present in normal ileum.

CONCLUSIONS

Although there was no gross evidence of small bowel intestinalization by the interposed segments, there was evidence of adaptation which was not merely an extension of the adaptive process seen after SBR alone. These changes resulted in the colon taking on some small bowel features. There was no significant difference between proximal vs distal interposed segments.

Fluoroacetate content of some species of the toxic Australian plant genus, Gastrolobium, and its environmental persistence

Gas chromatography confirmed the relatively high concentrations of fluoroacetate found in toxic Gastrolobiums, a genus of indigenous Australian plants. Fluoroacetate concentration in these plants ranged from 0.1 to 3875 micrograms/g (ppm) dry weight, with young leaves and flowers containing the highest concentrations. However, there was considerable intrastand variation between individual plants of at least two species with coefficients of variation ranging from 94% to 129%. Despite the high concentrations of fluoroacetate in many species, only one of nine soil samples collected from beneath these plants contained fluoroacetate. None of the 16 water samples collected from nearby streams and catchment dams contained fluoroacetate. This suggests that fluoroacetate does not persist in this environment. Fluoroacetate was also found in the genus Nemcia, and very low levels of fluoroacetate (ng/g) were detected in the foodstuffs, tea and guar gum. The latter indicates that other plant species may produce biologically insignificant amounts of fluoroacetate.

Intraoperative detection and resection of occult neuroblastoma: a technique exploiting somatostatin receptor expression

Tumor cell expression of specific high-affinity somatostatin receptors has been associated with a favorable prognosis in children with neuroblastoma. The purpose of this study was (1) to document intraoperatively the in vivo binding of the somatostatin analogue 125I-tyr3-octreotide to high-affinity somatostatin receptors expressed on human neuroblastoma, using a hand-held gamma detector; (2) to determine whether gamma-probe detection of radioligand binding to tumor receptors could identify occult malignancy; and (3) to determine the safety and biodistribution of 125I-tyr3-octreotide in children. Six children with stage III or IV neuroblastoma received an intravenous injection of 125I-tyr3-octreotide and underwent operative exploration using gamma-probe detection of radioligand binding to tumor somatostatin receptors. Tissue that demonstrated in vivo binding of 125I-tyr3-octreotide, or that was suspicious for tumor, was extirpated and analyzed by histopathology, immunohistochemistry, and microautoradiography. The biodistribution of 125I-tyr3-octreotide was recorded intraoperatively over time. Tumor tissue from each child also was assayed in vitro for somatostatin receptor expression by competitive binding studies using 125I-tyr3-octreotide. In vivo binding of 125I-tyr3-octreotide to malignant tissue was documented in the five children with a known tumor burden. Seventeen sites of radioreceptor binding were amenable to resection. Histopathological analysis confirmed neuroblastoma in 15 of these specimens. Four of the 15 proven tumor foci were occult malignancies. Every site of histologically proven neuroblastoma demonstrated in vivo binding of 125I-tyr3-octreotide. Five of seven sites histologically negative for neuroblastoma also were negative for in vivo radioreceptor binding. Microautoradiography confirmed in vivo binding of 125I-tyr3-octreotide to tumor cells. Uptake of 125I-tyr3-octreotide in abdominal organs occurred within 15 minutes of injection, was highest in the liver and gallbladder, and decreased over 24 hours. The conclusions were as follows. (1) 125I-tyr3-octreotide binds, in vivo, to somatostatin receptors on neuroblastoma, with 100% sensitivity and 71% specificity. (2) Occult neuroblastoma is found through gamma-probe detection of radioligand binding to receptors. (2) The biodistribution of 125I-tyr3-octreotide reflects the hepatobiliary clearance of this radionuclide. (4) Radioreceptor-guided surgery may safely provide more complete operative staging and cytoreduction of neuroblastoma.

Pediatric cervical-spine immobilization: achieving neutral position?

This study was designed to evaluate prospectively the ability of current spine-immobilization devices to achieve radiographic-neutral positioning of the cervical spine in pediatric trauma patients. All trauma patients who required spinal immobilization and a lateral cervical spine radiograph were included in the study. A lateral cervical spine radiograph was obtained while the child was immobilized. The Cobb angle (C2-C6) was measured using a handheld goniometer. The method of immobilization, age at injury, and Cobb angle were compared. One hundred and eighteen patients with an average age of 7.9 years were enrolled. The majority were males (71%). The most frequent mechanisms of injury included motor vehicle accidents (35%) and falls (32%). The average Glascow Coma Scale score was 14. Although 31% of the children complained of neck pain, 92% were without neurologic deficits. The Cobb angles ranged from 27 degree kyphosis to 27 degree lordosis, and only 12 of the patients presented in a neutral position (0 degrees). Greater than 5 degrees of kyphosis or lordosis was observed in 60% of the children. Thirty-seven percent of the patients had 10 degrees or greater angulation. The most frequent methods of immobilization included a collar, backboard, and towels (40%), and a collar, backboard, and blocks (20%), but these techniques provided < 5 degrees kyphosis or lordosis in only 45% and 26% of the children respectively. No single method or combination of methods of immobilization consistently placed the children in the neutral position.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative identification of parathyroid gland pathology: a new approach

Technetium 99m-sestamibi, a radiopharmaceutical used for the diagnostic imaging of abnormal parathyroid tissue, and the Neoprobe 1000, a hand-held, gamma-detecting probe, were used concurrently, during surgical exploration, in three children with hyperparathyroidism. This novel combination assisted with the identification of an ectopic mediastinal parathyroid adenoma and with the localization of multiple hyperplastic parathyroid glands. 99mTc-sestamibi combined with the Neoprobe 1000 may prove to be a useful adjunctive technique for the intraoperative localization of abnormal parathyroid tissue in selected patients.

Congenital diaphragmatic hernia and profound prematurity: report of a survivor

Congenital diaphragmatic hernia (CDH) continues to be one of the most challenging problems in pediatric surgery. The overall mortality rate remains at 40%, and death is caused by pulmonary hypoplasia and persistent pulmonary hypertension. It has been suggested that in utero repair of the defect should be performed to allow the lungs to grow and develop, in the hope of preventing fatal pulmonary insufficiency. The authors report the survival of a 960-g premature infant with CDH, suggesting that ex utero repair is possible in a very low birth weight infant.

Neonatal soft tissue sarcomas: the influence of pathology on treatment and survival. Children's Cancer Group Surgical Committee

INTRODUCTION

A multi-institutional study was conducted by the Children's Cancer Group (CCG) to evaluate all soft tissue sarcomas diagnosed within the first month of life.

METHODS

A retrospective study by 11 CCG institutions of patient records from 1971 to 1991 were reviewed for demographic data, pathology, therapy, and outcome.

RESULTS

32 neonates with soft tissue sarcomas were identified. There were 21 boys and 11 girls. Pathology was equally divided into three groups: Congenital fibrosarcoma (CFS) (12), rhabdomyosarcoma (RMS) (11), and non-RMS soft tissue sarcomas (NRSTS) (9). Anatomic sites consisted of head/neck (11), extremity (9), trunk (8), pelvis (3), and unknown (2). Overall survival rate was 59% (19/32).

CONCLUSION

Soft tissue sarcomas in the neonate comprise three general groups with survival rates dependent on pathology and extent of disease.

Diagnosis, management, and outcome of cervicofacial teratomas in neonates: a Childrens Cancer Group study

The management of cervicofacial teratomas in neonates is often complicated and may result in significant morbidity and death. A Childrens Cancer Group (CCG) retrospective study was conducted to evaluate a multiinstitutional experience with the treatment of these extremely rare neoplasms. Twenty neonates with cervicofacial teratomas, presenting from 1971 to 1994, were identified from nine CCG institutions. Fourteen neonates had cervical teratomas, and six had orofacial teratomas. There were 12 males and eight females. A diagnostic prenatal ultrasound examination was performed in six cases. Life-threatening airway obstruction occurred in seven infants (35%) in the early postnatal period. Two neonates died in the delivery room without ever having their airway secured. Two other infants with a prenatal diagnosis survived only because tracheostomies were performed by pediatric surgeons who were in the delivery room. Three other patients were orally intubated, one after sustaining hypoxic cardiac arrest. Eighteen infants had their primary tumor excised. Three patients required tracheostomy. After resection, two patients had evidence of unilateral recurrent laryngeal nerve injury, and two required prolonged thyroid hormone replacement. Histological examination showed eight mature and seven immature teratomas. Four infants (20%) clearly had malignant lesions. Pulmonary metastases occurred in two patients and contributed to one late death at 6 months of age. The overall survival rate was 85%, and the mean follow-up period was 5 years (range, 2 months to 16 years). Twelve of 17 surviving patients (70%) have had an excellent functional and cosmetic outcome. Four children have varying degrees of developmental delay and mental retardation. Hypoxia at birth was believed to have contributed to these problems in two cases.(ABSTRACT TRUNCATED AT 250 WORDS)