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1.
Am J Infect Control ; 52(5): 618-620, 2024 May.
Article in English | MEDLINE | ID: mdl-38211666

ABSTRACT

Previously, blood and body fluid exposures were managed by a visit to the University Employee Health Clinic during normal business hours and the Emergency Department after hours. We implemented the "S-T-I-C-K" program where health care personnel were evaluated immediately after exposure by a nurse-driven 24/7 hotline. Increasing accessibility to care and a simplified process for exposure management led to a significant decrease in Emergency Department utilization and time between the exposure and receipt of post-exposure prophylaxis.

2.
Musculoskeletal Care ; 21(2): 312-337, 2023 06.
Article in English | MEDLINE | ID: mdl-37316969

ABSTRACT

INTRODUCTION: The burden of Musculoskeletal disorders (MSD) is large. Surgery is an important management option but the factors that shape patients' surgical decisions are not well understood. As prior reviews have explored only single data types or conditions, a mixed methods appraisal across the musculoskeletal spectrum was undertaken. METHODS: A mixed-methods systematic, convergent segregated approach was used, with PubMed, Cumulated Index to Nursing and Allied Health Literature (CINHAL), Embase and PsycINFO searched to identify studies of adult patients' decisions about whether to undergo surgery. A narrative synthesis was conducted, with identified themes integrated across quantitative, qualitative and mixed-methods studies. RESULTS: Forty-six studies were included (24 quantitative, 19 qualitative and three mixed methods), with four decision-making themes identified (symptoms, sociodemographic and health factors, information and perceptions). Decision-making involves a complex interaction of individual sociodemographic, health and symptom information, integrated with individual perceptions of candidacy and surgical expectations. While most studies investigated hip and knee surgery, across all included conditions, patients are more likely to favour surgery if symptoms and/or dysfunction are higher, and if perceptions of surgical candidacy and processes (outcomes, inconvenience, and risk) are favourable. Other factors including age, general health, race, financial context, professional and non-professional communication, and information sources also impact decision-making but exert a less consistent impact upon the propensity to prefer surgery. CONCLUSION: Patients are more likely to choose surgery for MSD when they have higher levels of symptoms or dysfunction and positive perceptions of surgical suitability and expectations. Other factors important to individuals, have a less consistent impact upon the propensity to prefer surgery. These findings have potential to aid the efficient referral of patients to orthopaedics. More research is needed to validate these findings across the spectrum of MSD.


Subject(s)
Musculoskeletal Diseases , Orthopedic Procedures , Orthopedics , Adult , Humans , Information Sources , Musculoskeletal Diseases/surgery , Patient Preference
3.
Epileptic Disord ; 25(3): 360-370, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37070482

ABSTRACT

RATIONALE: Glucose transporter type I deficiency syndrome (GLUT1-DS) is the fourth most frequent single-gene epilepsy refractory to standard antiepileptic drugs. Multiple seizure types and variable electrographic findings are reported. Ketogenic diet is expected to result in the complete resolution of the epileptiform activity. METHODS: A retrospective chart review of patients with GLUT1-DS on ketogenic diet between December 2012 and February 2022 was done. Analysis of the EEGs prior to and during the ketogenic diet was done. RESULTS: 34 patients on ketogenic diet were reviewed. Ten had clinical diagnosis of GLUT1-DS, and seven of them had genetic confirmation. 71% were female. The average age at seizure onset was 13.85 m.o. (range: 3-60, SD ±20.52), at diagnosis was 44.57 m.o (range: 19-79), and at the onset of ketogenic diet was 46.43 m.o. (range: 20-83). 29 months (range: 13-38) delay between symptoms onset until diagnosis was noticed. At the diagnosis 100% reported seizures: 71% myoclonic, 57% generalized motor, 57% absence, 28% atonic, and 14% focal motor. Also, 71% abnormal eye movements, 57% ataxia, and 28% intolerance to fasting. 86% had normal brain MRI. 71% had abnormal EEG. All were on ketogenic diet, and four on classical (1.75:1-2.25:1 ratio). Six were clinically seizure-free after the ketogenic diet. EEG features included notch delta, focal spike and wave, and generalized spike/polyspike and wave. One patient had bilateral independent centrotemporal spikes. Spikes showed high and very high amplitude in all of them (>200 µV). The variation of the spike index decreased in three patients but increased in two. CONCLUSION: Ketogenic diet is the choice treatment for patients with GLUT1-DS. Electrographic features could show worsening after initiation of the ketogenic diet even with seizure control. EEG did not prove to be a reliable tool for adjusting KD in our cohort. Centrotemporal spikes have not been reported in patients with GLUT-1 DS.


Subject(s)
Diet, Ketogenic , Epilepsy , Humans , Female , Male , Epilepsy/genetics , Retrospective Studies , Glucose Transporter Type 1 , Seizures , Electroencephalography , Syndrome
5.
J Child Neurol ; 37(4): 298-302, 2022 03.
Article in English | MEDLINE | ID: mdl-35040697

ABSTRACT

Objectives: To examine the clinical features, course, and management of children at age <2 years with tremor. Methods:Retrospective chart review of all patients aged <2 years presenting to a tertiary care neurology clinic between 2005 and 2019. Descriptive and inferential statistics were used. Results: We identified 29 children with tremor presenting at age <2 years. The mean age at onset, diagnosis and follow-up was 3.22 months (SD 3.63), 6.97 months (SD 5.44), and 10.83 months (SD 5.29), respectively. Tremor was more noticeable surrounding eating, sleep, or extreme emotions. The tremor did not interfere with development or require pharmacologic treatment in any patient. At follow-up, 31% had complete resolution of their tremor with the rest being stable or improved. Patients with resolved tremor were statistically more likely to have a younger age of diagnosis (F = 3.895, P = .033), no medical history (P = .029, χ2 = 7.112), and leg tremor (P = .028, χ2 = 7.143). Conclusion: Tremor with onset at age <2 years follows a benign course, with many patients requiring no treatment and outgrowing the disorder.


Subject(s)
Tremor , Child , Child, Preschool , Humans , Infant , Retrospective Studies , Tertiary Healthcare , Tremor/diagnosis , Tremor/drug therapy
6.
Paediatr Child Health ; 26(8): 458-461, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34987676

ABSTRACT

Disruptive behaviour disorders (DBDs)-which can include or be comorbid with disorders such as attention-deficit hyperactivity disorder, oppositional defiant disorder, conduct disorder and disruptive mood dysregulation disorder-are commonly seen in paediatric practice. Given increases in the prescribing of atypical antipsychotics for children and youth, it is imperative that paediatric trainees in Canada receive adequate education on the optimal treatment of DBDs. We describe the development, dissemination, and evaluation of a novel paediatric resident curriculum for the assessment and treatment of DBDs in children and adolescents. Pre-post-evaluation of the curriculum showed improved knowledge in participants.

7.
Front Neurol ; 11: 598531, 2020.
Article in English | MEDLINE | ID: mdl-33324337

ABSTRACT

A 39-year-old lady with relapsing myelin oligodendrocyte glycoprotein antibody (MOG-IgG) associated disease developed coryzal symptoms, malaise, sweating, and postural dizziness. Six days later she presented with painful progressive right visual loss consistent with optic neuritis. COVID-19 was confirmed by nasopharyngeal swab and MOG-IgG serological reversion was noted. Visual function improved following steroids and plasma exchange. This case highlights a possible causal association between inflammation due to COVID-19 and a relapse of MOG-IgG associated disease. It also highlights the clinical relevance of reporting MOG-IgG titers in MOG-IgG associated disease.

8.
Epilepsy Behav ; 112: 107324, 2020 11.
Article in English | MEDLINE | ID: mdl-32721873

ABSTRACT

OBJECTIVE: Adolescents with epilepsy are known to have a lower quality of life (QoL) than the typically developing adolescent population. In order to address this, treating physicians have primarily focused on obtaining seizure control. However, growing evidence suggests a strong relation between QoL and mental health in adults with epilepsy and other chronic conditions. Given the high rate of mental health issues in transition-aged adolescents with epilepsy, this study aimed to examine the relation between QoL and mental health. METHODS: Baseline data from 107 transition-aged adolescents (M = 16.08 years; 52 males, 55 females) enrolled in an epilepsy transition clinic were analyzed for this study. RESULTS: Analysis found that over 56% of participants showed some signs of mental illness, and that these participants had significantly lower QoL scores than those without mental health issues. Furthermore, regression analysis found that both depression and anxiety remained significant, independent predictors of QoL, even when significant epilepsy and demographic variables were accounted for (t(99) = -1.28, p < .001 and t(99) = -1.10, p = .002, respectively). SIGNIFICANCE: Results suggest that in order to ensure best outcomes for these adolescents, it may be important for clinicians to take a holistic approach to treatment, managing and treating both seizures and mental health concerns.


Subject(s)
Epilepsy , Quality of Life , Adolescent , Adult , Aged , Anxiety/etiology , Depression , Epilepsy/epidemiology , Epilepsy/therapy , Female , Humans , Male , Mental Health , Surveys and Questionnaires
9.
J R Coll Physicians Edinb ; 49(2): 118-121, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31188339

ABSTRACT

Giant cell arteritis is the most common primary systemic vasculitis in adults aged ≥50 years and peaks in the eighth decade of life. Common symptoms include headache, scalp tenderness and jaw claudication. Elevated acute phase reactants (erythrocyte sedimentation rate and C-reactive protein) are present in >90% of patients. Visual loss is a well-recognised complication, but approximately 2-4% of giant cell arteritis patients experience stroke, most frequently in the vertebrobasilar territory. We describe a 72-year-old male who developed bilateral vertebral artery occlusion and middle cerebellar peduncle infarction secondary to giant cell arteritis in spite of high-dose steroids.


Subject(s)
Anti-Inflammatory Agents/therapeutic use , Giant Cell Arteritis/drug therapy , Methylprednisolone/therapeutic use , Vertebrobasilar Insufficiency/complications , Aged , Antirheumatic Agents/therapeutic use , Cerebral Infarction/diagnostic imaging , Cerebral Infarction/etiology , Cyclophosphamide/therapeutic use , Giant Cell Arteritis/complications , Humans , Male
10.
Thyroid ; 28(12): 1682-1693, 2018 12.
Article in English | MEDLINE | ID: mdl-30351224

ABSTRACT

BACKGROUND: Thyroid autoimmunity, especially Graves' disease or hypothyroidism with positive autoantibodies (TRAb) to the thyrotropin receptor (TSHR), occurs in 30-40% of patients with relapsing multiple sclerosis following treatment with alemtuzumab (ALTZ). ALTZ therapy therefore provides a unique opportunity to study the evolution of TRAb prior to clinical presentation. TRAb can stimulate (TSAb), block (TBAb), or not affect ("neutral") the TSHR function, causing hyperthyroidism, hypothyroidism, or euthyroidism, respectively. METHODS: A longitudinal retrospective analysis was conducted of TRAb bioactivity over a period of nine years in 45 multiple sclerosis patients receiving ALTZ using available stored serum. Of these 45 patients, 31 developed thyroid dysfunction (TD) and 14 remained euthyroid despite being followed for a minimum of five years (NO-TD). The presence of TRAb was evaluated at standardized time points: (i) before ALTZ, (ii) latest time available following ALTZ and before TD onset, and (iii) following ALTZ during/after TD onset. Serum TRAb were detected by published in-house assays (ihTRAb): flow cytometry detecting any TSHR-binding TRAb, and luciferase bioassays detecting TSAb/TBAb bioactivity. Purified immunoglobulin G was used to verify TSAb/TBAb in selected hypothyroid cases. Standard clinical automated measurements of TRAb, antithyroid peroxidase autoantibodies (TPOAb), thyrotropin, free thyroxine, and free triiodothyronine were also collected. RESULTS: Before ALTZ, combined ihTRAb (positive with flow cytometry and/or luciferase bioassay) but not automated TRAb were present in 5/16 (31.2%) TD versus 0/14 (0%) NO-TD (p = 0.017). Detectable ihTRAb preceded TD development in 9/28 (32.1%) and by a median of 1.2 years (range 28 days-7.3 years). Combination testing of ihTRAb and TPOAb at baseline predicted 20% of subsequent cases of hyperthyroidism and 83% of hypothyroidism. CONCLUSIONS: Evidence is presented that TRAb measured with custom-made assays can be detected prior to any change in thyroid function in up to a third of cases of ALTZ-related TD. Furthermore, the presence of ihTRAb prior to ALTZ treatment was strongly predictive of subsequent TD. The findings suggest that a period of affinity maturation of TRAb may precede clinical disease onset in some cases. Combined testing of TPOAb and ihTRAb may increase the ability to predict those who will develop TD following ALTZ.


Subject(s)
Alemtuzumab/therapeutic use , Autoantibodies/blood , Receptors, Thyrotropin/immunology , Adult , Female , Humans , Hyperthyroidism/immunology , Hypothyroidism/immunology , Immunoglobulins, Thyroid-Stimulating/blood , Longitudinal Studies , Luciferases/metabolism , Male , Middle Aged , Multiple Sclerosis/complications , Multiple Sclerosis/drug therapy , Retrospective Studies , Thyroid Gland/drug effects , Thyroid Gland/physiopathology , Thyrotropin/blood
11.
J Clin Endocrinol Metab ; 103(8): 3010-3018, 2018 08 01.
Article in English | MEDLINE | ID: mdl-29878256

ABSTRACT

Context: Alemtuzumab, a highly effective treatment for multiple sclerosis (MS), predisposes to Graves disease (GD), with a reportedly indolent course. Objective: To determine the type, frequency, and course of thyroid dysfunction (TD) in a cohort of alemtuzumab-treated patients with MS in the United Kingdom. Design: Case records of alemtuzumab-treated patients who developed TD were reviewed. Results: A total of 41.1% (102 out of 248; 80 female and 22 male) of patients developed TD, principally GD (71.6%). Median onset was 17 months (range 2 to 107) following the last dose, with the majority (89%) within 3 years. Follow-up data (range 6 to 251 months) were available in 71 case subjects, of whom 52 (73.2%) developed GD: 10 of these (19.2%) had fluctuating TD. All 52 patients with GD commenced antithyroid drugs (ATDs): 3 required radioiodine (RAI) due to ATD side effects, and drug therapy is ongoing in 2; of those who completed a course, 16 are in remission, 1 developed spontaneous hypothyroidism, and 30 (64%) required definitive or long-term treatment (RAI, n = 17; thyroidectomy, n = 5; and long-term ATDs, n = 8). Three cases of thyroiditis and 16 cases of hypothyroidism were documented: 5 with antithyroid peroxidase antibody positivity only, 10 with positive TSH receptor antibody (TRAb), and 1 of uncertain etiology. Bioassay confirmed both stimulating and blocking TRAb in a subset of fluctuating GD cases. Conclusions: Contrary to published literature, we recorded frequent occurrence of GD that required definitive or prolonged ATD treatment. Furthermore, fluctuating thyroid status in GD and unexpectedly high frequency of TRAb-positive hypothyroidism suggested changing activity of TRAb in this clinical context; we have documented the existence of both blocking and stimulating TRAb in these patients.


Subject(s)
Alemtuzumab/adverse effects , Multiple Sclerosis/drug therapy , Thyroid Diseases/chemically induced , Thyroid Diseases/immunology , Thyroid Diseases/pathology , Adult , Disease Progression , Female , Graves Disease/chemically induced , Graves Disease/epidemiology , Graves Disease/immunology , Graves Disease/pathology , Humans , Male , Middle Aged , Multiple Sclerosis/epidemiology , Multiple Sclerosis/immunology , Retrospective Studies , Thyroid Diseases/epidemiology , Thyroiditis/chemically induced , Thyroiditis/epidemiology , Thyroiditis/immunology , Thyroiditis/pathology , Young Adult
12.
Arch Womens Ment Health ; 19(1): 113-24, 2016 Feb.
Article in English | MEDLINE | ID: mdl-25902956

ABSTRACT

This study investigated the quality of mother-infant interaction and maternal ability to recognise adult affect in three study groups consisting of mothers with a diagnosis of schizophrenia, mothers with depression and healthy controls. Sixty-four mothers were recruited from a Mother and Baby Unit and local children's centres. A 5-min mother-infant interaction was coded on a number of caregiving variables. Affect recognition and discrimination abilities were tested via a series of computerised tasks. Group differences were found both in measures of affect recognition and in the mother-infant interaction. Mothers with schizophrenia showed consistent impairments across most of the parenting measures and all measures of affect recognition and discrimination. Mothers with depression fell between the mothers with schizophrenia and healthy controls on most measures. However, depressed women's parenting was not significantly poorer than controls on any of the measures, and only showed trends for differences with mothers with schizophrenia on a few measures. Regression analyses found impairments in affect recognition and a diagnosis of schizophrenia to predict the occurrence of odd or unusual speech in the mother-infant interaction. Results add to the growing body of knowledge on the mother-infant interaction in mothers with schizophrenia and mothers with depression compared to healthy controls, suggesting a need for parenting interventions aimed at mothers with these conditions. While affect recognition impairments were not found to fully explain differences in parenting among women with schizophrenia, further research is needed to understand the psychopathology of parenting disturbances within this clinical group.


Subject(s)
Affect , Expressed Emotion , Mother-Child Relations , Mothers/psychology , Parenting/psychology , Schizophrenic Psychology , Adult , Case-Control Studies , Child , Depression, Postpartum , Facial Expression , Female , Humans , Infant , Maternal Behavior , Recognition, Psychology , Schizophrenia/epidemiology
13.
J Clin Child Adolesc Psychol ; 44(1): 80-92, 2015.
Article in English | MEDLINE | ID: mdl-24245908

ABSTRACT

Aggression in children is associated with an enhanced tendency to attribute hostile intentions to others. However, limited information is available regarding the factors that contribute to the development of such hostile attribution tendencies. We examined factors that contribute to individual differences in child hostile attributions and aggression, focusing on potential pathways from maternal hostile attributions via negative parenting behavior. We conducted a longitudinal study of 98 mothers and children (47 male, 51 female), recruited from groups experiencing high and low levels of psychosocial adversity. Maternal hostile attributions, observed parenting, and child behaviour were assessed at 18 months and 5 years child age, and child hostile attributions were also examined at 5 years. Independent assessments of maternal and child processes were utilized where possible. Analyses provided support for a direct influence of maternal hostile attributions on the development of child hostile attributions and aggressive behaviour. Maternal hostile attributions were also associated with negative parenting behaviour, which in turn influenced child adjustment. Even taking account of possible parenting influences and preexisting child difficulties, hostile attributions in the mother showed a direct link with child aggression at 5 years. Maternal hostile attributions were themselves related to psychosocial adversity. We conclude that maternal hostile attributions are prevalent in high-risk samples and are related to less optimal parenting behaviour, child hostile attributions, and child aggression. Targeting hostile maternal cognitions may be a useful adjunct to parenting programs.


Subject(s)
Aggression/psychology , Child Behavior/psychology , Hostility , Mothers/psychology , Parenting/psychology , Adaptation, Psychological , Child, Preschool , Female , Humans , Infant , Longitudinal Studies , Male
14.
BMC Health Serv Res ; 14: 600, 2014 Dec 05.
Article in English | MEDLINE | ID: mdl-25477157

ABSTRACT

BACKGROUND: Traumatic spinal cord injury is a devastating condition impacting adversely on the health and wellbeing, functioning and independence, social participation and quality of life of the injured person. In Australia, there are approximately 15 new cases per million population per year; economic burden estimates suggest 2 billion dollars annually. For optimal patient outcomes expert consensus recommends expeditious transfer ("<24 hours of injury") to a specialist Spinal Cord Injury Unit, where there is an interdisciplinary team equipped to provide comprehensive care for the many and complex issues associated with traumatic spinal cord injury. No study of this patient population has been undertaken, that assessed the extent to which care received reflected clinical guidelines, or examined the patient journey and outcomes in relation to this. The aims of this study are to describe the nature and timing of events occurring before commencement of specialist care, and to quantify the association between these events and patient outcomes. METHODS AND DESIGN: The proposed observational study will recruit a prospective cohort over two years, identified at participating sites across two Australian states; Victoria and New South Wales. Included participants will be aged 16 years and older and diagnosed with a traumatic spinal cord injury. Detailed data will be collected from the point of injury through acute care and subacute rehabilitation, discharge from hospital and community reintegration. Items will include date, time, location and external cause of injury; ambulance response, assessments and management; all episodes of hospital care including assessments, vital signs, diagnoses and treatment, inter-hospital transfers, surgical interventions and their timing, lengths of stay and complications. Telephone follow-up of survivors will be conducted at 6, 12 and 24 months. DISCUSSION: There is limited population level data on the effect of delayed commencement of specialist care (>24 hours) in a Spinal Cord Injury Unit. Examining current health service and clinical intervention pathways in this Australian population-based sample, in relation to their outcomes, will provide an understanding of factors associated with patient flow, resource utilisation and cost, and patient and family quality of life. Barriers to streamlined effective early-care pathways and facilitators of optimal treatment for these patients will be identified.


Subject(s)
Health Services Accessibility , Quality of Health Care , Quality of Life , Specialization , Spinal Cord Injuries/therapy , Australia , Critical Care , Female , Humans , Male , Middle Aged , New South Wales , Patient Discharge , Prospective Studies , Treatment Outcome , Victoria
15.
J Abnorm Child Psychol ; 35(4): 594-604, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17351751

ABSTRACT

Child externalising symptoms are associated with a bias towards attributing hostile intent to others. We examined the role of parental attributions in the development of this hostile attribution bias in children. The parents of 134 children aged 5-7 years responded to hypothetical social scenarios examining a) their general tendency to attribute hostile intent to the ambiguous behaviour of others, and b) hostile attributions made specifically to their child. Children's own attributions of hostile intent and levels of externalising symptomatology were assessed. The results indicated that child externalising symptoms were positively associated with both a generalised tendency towards the attribution of hostile intent and child-specific hostile attributions in parents. Child externalising symptoms were themselves associated with hostile attributions made by the child. However, no direct associations were observed between parental and child attributions of hostile intent. Thus, although the results suggest a role for parental social information processing biases in the development of child externalising symptoms, a direct transmission of such biases from parent to child was not supported.


Subject(s)
Culture , Fathers/psychology , Hostility , Intention , Mothers/psychology , Social Perception , Aggression/psychology , Agonistic Behavior , Attention Deficit Disorder with Hyperactivity/diagnosis , Attention Deficit Disorder with Hyperactivity/psychology , Child , Child, Preschool , Conduct Disorder/diagnosis , Conduct Disorder/psychology , Female , Humans , Internal-External Control , Male , Personality Assessment , Sex Factors , Socialization , Surveys and Questionnaires
16.
Europace ; 7 Suppl 2: 128-34, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16102510

ABSTRACT

AIMS: To develop an ionic model of stretch-activated and stretch-modulated currents in rabbit ventricular myocytes consistent with experimental observations, that can be used to investigate the role of these currents in intact myocardium. METHODS AND RESULTS: A non-specific cation-selective stretch-activated current I(ns), was incorporated into the Puglisi-Bers ionic model of epicardial, endocardial and midmyocardial ventricular myocytes. Using the model, we predict a reduction in action potential duration at 20% repolarization (APD(20)) and action potential amplitude, an elevated resting transmembrane potential and either an increase or decrease in APD(90), depending on the reversal potential of I(ns). A stretch-induced decrease in I(K1) (70%), plus a small I(ns) current (g(ns) = 10 pS), results in a reduction in APD(20) and increase in APD(90), and a reduced safety factor for conduction. Increasing I(K1) (150%) plus a large I(ns) current (g(ns) = 40 pS), also leads to a reduction in APD(20) and increase in APD(90), but with a greater safety factor. Endocardial and midmyocardial cells appear to be the most sensitive to stretch-induced changes in action potential. The addition of the K(+)-specific stretch-activated current (SAC) I(Ko) results in action potential shortening. CONCLUSION: Transmural heterogeneity of I(Ko) may reduce repolarization gradients in intact myocardium caused by intrinsic ion channel densities, nonuniform strains and electrotonic effects.


Subject(s)
Heart Conduction System/physiology , Myocytes, Cardiac/physiology , Ventricular Function , Action Potentials/physiology , Animals , Computer Simulation , Heart Ventricles/cytology , Ion Channels/metabolism , Rabbits , Stress, Mechanical
17.
Circ Res ; 95(12): 1216-24, 2004 Dec 10.
Article in English | MEDLINE | ID: mdl-15528464

ABSTRACT

The KCNQ1-G589D gene mutation, associated with a long-QT syndrome, has been shown to disrupt yotiao-mediated targeting of protein kinase A and protein phosphatase-1 to the I(Ks) channel. To investigate how this defect may lead to ventricular arrhythmia during sympathetic stimulation, we use integrative computational models of beta-adrenergic signaling, myocyte excitation-contraction coupling, and action potential propagation in a rabbit ventricular wedge. Paradoxically, we find that the KCNQ1-G589D mutation alone does not prolong the QT interval. But when coupled with beta-adrenergic stimulation in a whole-cell model, the KCNQ1-G589D mutation induced QT prolongation and transient afterdepolarizations, known cellular mechanisms for arrhythmogenesis. These cellular mechanisms amplified tissue heterogeneities in a three-dimensional rabbit ventricular wedge model, elevating transmural dispersion of repolarization and creating other T-wave abnormalities on simulated electrocardiograms. Increasing heart rate protected both single myocyte and the coupled myocardium models from arrhythmic consequences. These findings suggest that the KCNQ1-G589D mutation disrupts a critical link between beta-adrenergic signaling and myocyte electrophysiology, creating both triggers of cardiac arrhythmia and a myocardial substrate vulnerable to such electrical disturbances.


Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Amino Acid Substitution , Computer Simulation , Cytoskeletal Proteins/metabolism , Long QT Syndrome/etiology , Models, Cardiovascular , Models, Molecular , Mutation, Missense , Myocytes, Cardiac/metabolism , Point Mutation , Potassium Channels, Voltage-Gated/genetics , Receptors, Adrenergic, beta-1/physiology , Action Potentials/drug effects , Adrenergic beta-1 Receptor Agonists , Animals , Binding Sites , Computational Biology , Electrocardiography , Heart Ventricles/cytology , Ion Transport/drug effects , Isoproterenol/pharmacology , KCNQ Potassium Channels , KCNQ1 Potassium Channel , Long QT Syndrome/genetics , Long QT Syndrome/physiopathology , Myocardial Contraction , Potassium/metabolism , Potassium Channels, Voltage-Gated/chemistry , Potassium Channels, Voltage-Gated/metabolism , Protein Binding , Protein Conformation , Protein Interaction Mapping , Rabbits , Structure-Activity Relationship
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