Ronald M. Harper
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View article: Brain connectivity correlates of breathing and cardiac patterns in epilepsy: A study including SUDEP cases
Brain connectivity correlates of breathing and cardiac patterns in epilepsy: A study including SUDEP cases Open
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of premature mortality among people with epilepsy. Evidence from witnessed and monitored SUDEP cases indicates seizure-induced cardiovascular and respiratory failures; yet, t…
View article: Brain gray matter changes in children at risk for sudden unexpected death in epilepsy
Brain gray matter changes in children at risk for sudden unexpected death in epilepsy Open
Background Potential failing adult brain sites, stratified by risk, mediating Sudden Unexpected Death in Epilepsy (SUDEP) have been described, but are unknown in children. Methods We examined regional brain volumes using T1-weighted MRI im…
View article: Altered 5-HT2A/C receptor binding in the medulla oblongata in the sudden infant death syndrome (SIDS): Part II. Age-associated alterations in serotonin receptor binding profiles within medullary nuclei supporting cardiorespiratory homeostasis
Altered 5-HT2A/C receptor binding in the medulla oblongata in the sudden infant death syndrome (SIDS): Part II. Age-associated alterations in serotonin receptor binding profiles within medullary nuclei supporting cardiorespiratory homeostasis Open
The failure of chemoreflexes, arousal, and/or autoresuscitation to asphyxia may underlie some sudden infant death syndrome (SIDS) cases. In Part I, we showed that some SIDS infants had altered 5-hydroxytryptamine (5-HT)2A/C receptor bindin…
View article: Altered amygdala volumes and microstructure in focal epilepsy patients with <scp>tonic–clonic</scp> seizures, ictal, and post‐convulsive central apnea
Altered amygdala volumes and microstructure in focal epilepsy patients with <span>tonic–clonic</span> seizures, ictal, and post‐convulsive central apnea Open
Objectives Sudden unexpected death in epilepsy (SUDEP) is a leading cause of death for patients with epilepsy; however, the pathophysiology remains unclear. Focal‐to‐bilateral tonic–clonic seizures (FBTCS) are a major risk factor, and cent…
View article: Intermittent hypoxia in neonatal rodents affects facial bone growth
Intermittent hypoxia in neonatal rodents affects facial bone growth Open
Preterm human infants often show periodic breathing (PB) or apnea of prematurity (AOP), breathing patterns which are accompanied by intermittent hypoxia (IH). We examined cause-effect relationships between transient IH and reduced facial b…
View article: Brain Connectivity Correlates of Breathing and Cardiac Irregularities in SUDEP: A Resting-State fMRI Study
Brain Connectivity Correlates of Breathing and Cardiac Irregularities in SUDEP: A Resting-State fMRI Study Open
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of premature mortality among people with epilepsy. Evidence from witnessed and monitored SUDEP cases indicate seizure-induced cardiovascular and respiratory failures; yet, th…
View article: Volumetric and microstructural abnormalities of the amygdala in focal epilepsy with varied levels of SUDEP risk
Volumetric and microstructural abnormalities of the amygdala in focal epilepsy with varied levels of SUDEP risk Open
Although the mechanisms of sudden unexpected death in epilepsy (SUDEP) are not yet well understood, generalised- or focal-to-bilateral tonic-clonic seizures (TCS) are a major risk factor. Previous studies highlighted alterations in structu…
View article: Volumetric and microstructural abnormalities of the amygdala in focal epilepsy with varied levels of SUDEP risk
Volumetric and microstructural abnormalities of the amygdala in focal epilepsy with varied levels of SUDEP risk Open
Although the mechanisms of sudden unexpected death in epilepsy (SUDEP) are not yet well understood, generalised- or focal-to-bilateral tonic-clonic seizures (TCS) are a major risk factor. Previous studies highlighted alterations in structu…
View article: Altered Amygdala Volumes and Microstructure in Focal Epilepsy Patients with Tonic-Clonic Seizures, Ictal and Post-Ictal Central Apnea
Altered Amygdala Volumes and Microstructure in Focal Epilepsy Patients with Tonic-Clonic Seizures, Ictal and Post-Ictal Central Apnea Open
and key words Objectives Sudden unexpected death in epilepsy (SUDEP) is a leading cause of death for patients with epilepsy; however, the pathophysiology remains unclear. Focal-to-bilateral tonic-clonic seizures (FBTCS) are a major risk fa…
View article: Intermittent Hypoxia in Neonatal Rodents Affects Facial Bone Growth
Intermittent Hypoxia in Neonatal Rodents Affects Facial Bone Growth Open
Preterm human infants often show periodic breathing (PB) or apnea of prematurity (AOP), breathing patterns which are accompanied by intermittent hypoxia (IH). We examined cause-effect relationships between transient IH and reduced facial b…
View article: Exploring the brain with sleep-related injuries, and fixing it
Exploring the brain with sleep-related injuries, and fixing it Open
The focus of my research efforts rests with determining dysfunctional neural systems underlying disorders of sleep, and identifying interventions to overcome those disorders. Aberrant central and physiological control during sleep exerts s…
View article: Regional variation in brain tissue texture in patients with tonic-clonic seizures
Regional variation in brain tissue texture in patients with tonic-clonic seizures Open
Patients with epilepsy, who later succumb to sudden unexpected death, show altered brain tissue volumes in selected regions. It is unclear whether the alterations in brain tissue volume represent changes in neurons or glial properties, sin…
View article: Intermittent Hypoxia Interferes with Autocrine Effects of GABA on Insulin Secretion in Postnatal Rodents—Implications for Pediatric Obstructive Sleep Apnea
Intermittent Hypoxia Interferes with Autocrine Effects of GABA on Insulin Secretion in Postnatal Rodents—Implications for Pediatric Obstructive Sleep Apnea Open
Gamma-amino butyric acid (GABA) is well known to help elevate pancreatic β cell vitality and insulin levels in blood. GABA works via a coupling with GABA receptors; thus, the concentration of GABAA receptors on the plasma membrane of β cel…
View article: Inappropriate Ventilatory Homeostatic Responses in Hospitalized COVID-19 Patients
Inappropriate Ventilatory Homeostatic Responses in Hospitalized COVID-19 Patients Open
Background The clinical presentation of COVID-19 suggests altered breathing control - tachypnoea, relative lack of dyspnoea, and often a discrepancy between severity of clinical and radiological findings. Few studies characterize and analy…
View article: Baroreflex sensitivity during rest and pressor challenges in obstructive sleep apnea patients with and without CPAP
Baroreflex sensitivity during rest and pressor challenges in obstructive sleep apnea patients with and without CPAP Open
As expected, BRS was lower and BPV higher in OSA during the pressor challenges, and disease severity negatively correlated with BRS. In this cross-sectional study, both CPAP-treated (self-reported) and untreated OSA showed reduced BRS, lea…
View article: Sex differences in insular gyri responses to the cold pressor challenge
Sex differences in insular gyri responses to the cold pressor challenge Open
Introduction Sex differences in autonomic control may contribute to physiological sex differences in cardiovascular disease, thermoregulation, and the experience of pain. We previously showed sex differences in functional mapping of autono…
View article: Potential Mechanisms Underlying Hypoxia-Induced Diabetes in a Rodent Model: Implications for COVID-19
Potential Mechanisms Underlying Hypoxia-Induced Diabetes in a Rodent Model: Implications for COVID-19 Open
Previous studies reported that repetitive hypoxia in rat pups reduces insulin secretion and elevates fasting blood glucose levels; these sequelae persisted for several months. This report describes how episodic hypoxic events elevate a chl…
View article: Distinct Patterns of Brain Metabolism in Patients at Risk of Sudden Unexpected Death in Epilepsy
Distinct Patterns of Brain Metabolism in Patients at Risk of Sudden Unexpected Death in Epilepsy Open
Objective: To characterize regional brain metabolic differences in patients at high risk of sudden unexpected death in epilepsy (SUDEP), using fluorine-18-fluorodeoxyglucose positron emission tomography ( 18 FDG-PET). Methods: We studied p…
View article: Neuromodulatory Support for Breathing and Cardiovascular Action During Development
Neuromodulatory Support for Breathing and Cardiovascular Action During Development Open
Neonatal survival requires precise control of breathing and cardiovascular action, with fatal consequences or severe injury without support. Prematurity presents multiple opportunities to disrupt cardiorespiratory regulation, leading to ex…
View article: Pilot Safety and Feasibility Study of Non-invasive Limb Proprioceptive Cerebellar Stimulation for Epilepsy
Pilot Safety and Feasibility Study of Non-invasive Limb Proprioceptive Cerebellar Stimulation for Epilepsy Open
Cerebellar stimulation reduces seizures in animals and in humans with drug-resistant epilepsy. In a pilot safety and feasibility study, we applied continuous cutaneous vibratory stimulation (limb proprioceptive cerebellar stimulation) to f…
View article: Elevated Hyoid Bone Position in Response to Mandibular Advancing Appliance Predicts Effectiveness of the Appliance for Obstructive Sleep Apnea
Elevated Hyoid Bone Position in Response to Mandibular Advancing Appliance Predicts Effectiveness of the Appliance for Obstructive Sleep Apnea Open
The objective was to determine whether hyoid bone elevation induced by an anterior mandibular positioning appliance (AMP) predicts the effectiveness of the AMP in patients with obstructive sleep apnea (OSA). Fifteen patients (12 males and …
View article: Automated Analysis of Risk Factors for Postictal Generalized EEG Suppression
Automated Analysis of Risk Factors for Postictal Generalized EEG Suppression Open
Rationale: Currently, there is some ambiguity over the role of postictal generalized electro-encephalographic suppression (PGES) as a biomarker in sudden unexpected death in epilepsy (SUDEP). Visual analysis of PGES, known to be subjective…
View article: 428 Baroreflex sensitivity during handgrip in obstructive sleep apnea with and without CPAP
428 Baroreflex sensitivity during handgrip in obstructive sleep apnea with and without CPAP Open
Introduction Obstructive sleep apnea (OSA) disrupts multiple aspect of autonomic regulation; it is unclear whether intervention with continuous positive airway pressure (CPAP) can correct such disruptions. One key index of autonomic regula…
View article: 432 Brain Structure and Baroreflex Sensitivity Associations in Obstructive Sleep Apnea with and without CPAP
432 Brain Structure and Baroreflex Sensitivity Associations in Obstructive Sleep Apnea with and without CPAP Open
Introduction Obstructive sleep apnea (OSA) disrupts multiple aspects of autonomic regulation; it is unclear whether intervention with continuous positive airway pressure (CPAP) can correct such disruptions. One key index of autonomic regul…
View article: Which came first, obstructive sleep apnoea or hypertension? A retrospective study of electronic records over 10 years, with separation by sex
Which came first, obstructive sleep apnoea or hypertension? A retrospective study of electronic records over 10 years, with separation by sex Open
Objectives Obstructive sleep apnoea (OSA) is a risk factor for hypertension (HTN), but the clinical progression of OSA to HTN is unclear. There are also sex differences in prevalence, screening and symptoms of OSA. Our objective was to est…
View article: Insular functional organization during handgrip in females and males with obstructive sleep apnea
Insular functional organization during handgrip in females and males with obstructive sleep apnea Open
Study objectives Brain regulation of autonomic function in obstructive sleep apnea (OSA) is disrupted in a sex-specific manner, including in the insula, which may contribute to several comorbidities. The insular gyri have anatomically dist…
View article: Seizure Clusters, Seizure Severity Markers, and SUDEP Risk
Seizure Clusters, Seizure Severity Markers, and SUDEP Risk Open
Rationale: Seizure clusters may be related to Sudden Unexpected Death in Epilepsy (SUDEP). Two or more generalized convulsive seizures (GCS) were captured during video electroencephalography in 7/11 (64%) patients with monitored SUDEP in t…
View article: Association of Peri-ictal Brainstem Posturing With Seizure Severity and Breathing Compromise in Patients With Generalized Convulsive Seizures
Association of Peri-ictal Brainstem Posturing With Seizure Severity and Breathing Compromise in Patients With Generalized Convulsive Seizures Open
This study provides Class III evidence that peri-ictal brainstem posturing is associated with the GCS with more prolonged PGES and more severe breathing dysfunction.
View article: Peri‐ictal hypoxia is related to extent of regional brain volume loss accompanying generalized tonic‐clonic seizures
Peri‐ictal hypoxia is related to extent of regional brain volume loss accompanying generalized tonic‐clonic seizures Open
Objectives Hypoxia, or abnormally low blood‐oxygen levels, often accompanies seizures and may elicit brain structural changes in people with epilepsy which contribute to central processes underlying sudden unexpected death in epilepsy (SUD…
View article: Functional organization of the insula in men and women with obstructive sleep apnea during Valsalva
Functional organization of the insula in men and women with obstructive sleep apnea during Valsalva Open
Study Objectives Obstructive sleep apnea (OSA) patients show impaired autonomic regulation, perhaps related to functional reorganization of the insula, which in healthy individuals shows sex-specific anterior and right dominance during sym…