A5022205827- Heart Rate Variability and Autonomic Control
- Spinal Cord Injury Research
- Cardiovascular and exercise physiology
- Non-Invasive Vital Sign Monitoring
- Muscle activation and electromyography studies
- Stroke Rehabilitation and Recovery
- Cardiac Arrest and Resuscitation
- Cardiovascular Syncope and Autonomic Disorders
- Neuroscience of respiration and sleep
- Traumatic Brain Injury and Neurovascular Disturbances
- Optical Imaging and Spectroscopy Techniques
- Cardiac Health and Mental Health
- Cerebral Palsy and Movement Disorders
- Cardiovascular Health and Disease Prevention
- Thermoregulation and physiological responses
- Traumatic Brain Injury Research
- Blood Pressure and Hypertension Studies
- Sports Performance and Training
- Obstructive Sleep Apnea Research
- Cardiac electrophysiology and arrhythmias
- Sports injuries and prevention
- Diabetic Foot Ulcer Assessment and Management
- EEG and Brain-Computer Interfaces
- High Altitude and Hypoxia
- COVID-19 Clinical Research Studies
Spaulding Rehabilitation Hospital
2016-2025
Saint-Vincent Hospital
2021-2025
White River Technologies (United States)
2025
Harvard University
2015-2024
Spaulding Hospital
2015-2024
Royal Columbian Hospital
2023
Brigham and Women's Hospital
2022
Brown University
2022
Kent Hospital
2022
Massachusetts General Hospital
2014-2022
Background —Survival of post–myocardial infarction patients is related inversely to their levels very-low-frequency (0.003 0.03 Hz) RR-interval variability. The physiological basis for such oscillations unclear. In our study, we used blocking drugs evaluate potential contributions sympathetic and vagal mechanisms the renin-angiotensin-aldosterone system variability in 10 young healthy subjects. Methods Results —We recorded RR intervals arterial pressures during three separate sessions, with...
1. The reduction in vascular resistance which accompanies acute dynamic exercise does not subside immediately during recovery, resulting a post‐exercise hypotension. This sustained vasodilatation suggests that sympathetic regulation is altered after exercise. 2. Therefore, we assessed the baroreflex control of outflow response to arterial pressure changes, and transduction activity into sympatho‐excitatory stimulus (isometric handgrip exercise) either (60 min cycling at 60% peak aerobic...
Obstructive sleep apnoea syndrome (OSAS) causes nocturnal chronic intermittent hypoxia (IH) that contributes to excess cardiovascular morbidity. To explore the consequences of IH, we used our recently developed model IH in healthy humans characterise profile this blood pressure increase, determine if it is sustained and potential physiological mechanisms. We performed 24-h ambulatory monitoring 12 subjects before after 2 weeks exposure. also assessed systemic haemodynamics, muscle...
This paper highlights the major challenges and considerations for addressing COVID-19 in informal settlements. It discusses what is known about vulnerabilities how to support local protective action. There heightened concern urban settlements because of combination population density inadequate access water sanitation, which makes standard advice social distancing washing hands implausible. are further do with lack reliable data social, political economic contexts each setting that will...
Background One of the principal explanations for respiratory sinus arrhythmia is that it reflects arterial baroreflex buffering respiration-induced pressure fluctuations. If this explanation correct, then elimination RR interval fluctuations should increase Methods and Results We measured during normal rhythm fixed-rate atrial pacing at 17.2±1.8 (SEM) beats per minute greater than rate in 16 healthy men 4 women, 20 to 34 years age. Measurements were made controlled-frequency breathing (15...
Clinicians and experimentalists routinely estimate vagal-cardiac nerve traffic from respiratory sinus arrhythmia. However, evidence suggests that sympathetic mechanisms may also modulate Our study examined modulation of arrhythmia by outflow. We measured R-R interval spectral power in 10 volunteers breathed sequentially at 13 frequencies, 15 to 3 breaths/min, before after β-adrenergic blockade. fitted changes frequency with a damped oscillator model: frequency-dependent oscillations resonant...
The duration of antagonistic action nor-binaltorphimine (nor-BNI), a kappa antagonist, antinociception resulting from selective opioid agonists, was examined using the mouse tail-flick assay as endpoint. Nor-BNI (1 nmol, i.c.v. at -20 min) antagonized equiantinociceptive doses agonists (5 alpha,7 alpha,8 beta)-(-)-N-methyl-N-(7-(1-pyrrolidinyl)-1-oxaspiro (4,5)dec-8-yl) benzeneacetamide (U69,593) (70 nmol i.c.v.) or bremazocine (25 i.c.v.), but did not antagonize produced by mu...
The role of the sympathetic nervous system in cerebral autoregulation remains poorly characterized. We examined blood flow responses to augmented arterial pressure oscillations with and without blockade compared them forearm circulation.An oscillatory lower body negative 40 mm Hg was used at 6 frequencies from 0.03 0.08 Hz 11 healthy subjects alpha-adrenergic by phentolamine.Sympathetic resulted unchanged mean flow. transfer function relationship >0.05 significantly increased both brachial...
Despite growing evidence of autonomic nervous system involvement in the regulation cerebral blood flow, specific contribution cholinergic vasodilatation to autoregulation remains unknown. We examined and forearm flow responses augmented arterial pressure oscillations with without blockade. Oscillatory lower body negative was applied at six frequencies from 0.03 0.08 Hz nine healthy subjects blockade via glycopyrrolate. Cholinergic increased cross-spectral coherence between all except...
PURPOSE This phase I trial was undertaken to determine the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLTs) of B-cell-restricted immunotoxin anti-B4-blocked ricin (anti-B4-bR) when it is administered by 7-day continuous infusion. PATIENTS AND METHODS Thirty-four patients with relapsed refractory B-cell neoplasms (26 non-Hodgkin's lymphoma [NHL], four chronic lymphocytic leukemia [CLL], acute lymphoblastic [ALL]) received infusion anti-B4-bR. Successive cohorts at least three...
Spontaneously occurring, parallel fluctuations in arterial pressure and heart period are frequently used as indices of baroreflex function. Despite the convenience spontaneous indices, their relation to remains unclear. Therefore, 97 volunteers, we derived 5 proposed (sequence method, α-index, transfer function, low-frequency impulse response function), compared them with gain (by modified Oxford pharmacologic technique), examined carotid distensibility respiratory sinus arrhythmia. The...
The purpose of this study was to determine how breathing protocols requiring varying degrees control affect cardiovascular dynamics. We measured inspiratory volume, end-tidal CO 2 , R-R interval, and arterial pressure spectral power in 10 volunteers who followed the following 5 protocols: 1) uncontrolled for min; 2) stepwise frequency (at 0.3, 0.25, 0.2, 0.15, 0.1, 0.05 Hz min each); 3) as above, but with prescribed tidal volumes; 4) random-frequency (∼0.5–0.05 Hz) 6 5) fixed-frequency (0.25...
1. The notion that small, ‘non‐hypotensive’ reductions of effective blood volume alter neither arterial pressure nor baroreceptor activity is pervasive in the experimental literature. We tested two hypotheses: (a) minute and cardiac autonomic outflow changes during hypovolaemia induced by lower body suction humans are masked alterations breathing, (b) evidence for baroreflex engagement might be obtained from measurements thoracic aorta dimensions. 2. In studies, responses to graded at 0...
Usefulness of complex demodulation (CDM) in assessing the frequency components cardiovascular variability was assessed and, subsequently, this technique utilized to determine time-dependent responses low-frequency (LF) and high-frequency (HF) amplitudes heart rate blood pressure variabilities during postural tilt. CDM provides changes amplitude a particular component on continuous basis. Analysis simulated data showed that has sufficient resolution separately measure LF HF with time < 15...
The purpose of this study was to determine the respective contributions tachycardia and increases in sympathetic nerve activity (SNA) mediating pressor responses fatiguing vs. nonfatiguing levels isometric handgrip exercise (IHE) humans. We performed direct (microneurographic) measurements muscle SNA from right peroneal leg recorded arterial pressure (AP) heart rate (HR) eight healthy subjects before (control), during, after 2.5 min IHE at 15, 25, or 35% maximal voluntary contraction (MVC)....
Although myogenic mechanisms have been hypothesized to play a role in cerebrovascular regulation, previous data from both animals and humans not provided an unequivocal answer. However, cerebral autoregulation is explicitly non-linear most prior work relied on simple linear approaches for assessment, potentially missing important changes autoregulatory characteristics. Therefore, we examined blood flow responses augmented arterial pressure oscillations with without calcium channel blockade...
Physical rest after a concussion has been described as key component in the management of injury. Evidence supporting this recommendation, however, is limited.To examine association between physical activity and symptom duration cohort patients concussion.Cohort study; Level evidence, 2.This study included 364 who were diagnosed with concussion, seen by physician within 3 weeks injury, completed questionnaire at initial clinic visit. The assessed postconcussion scale (PCSS) score, previous...
A failure to fully recover following coronavirus disease 2019 (COVID-19) may have a profound impact on high-functioning populations ranging from frontline emergency services professional or amateur/recreational athletes. The aim of the study is describe medium-term cardiopulmonary exercise profiles individuals with "persistent symptoms" and who feel "recovered" after hospitalization mild-moderate community infection COVID-19 an age, sex, job-role matched control group. total 113 participants...
Background —We measured cardiovagal baroreflex gain and its vascular mechanical neural components during dynamic engagement in 10 young untrained men, 6 older 12 older, physically active men. Methods Results —Our newly developed assessment of beat-to-beat carotid diameters estimates the transduction pressure into barosensory stretch (Δdiameter/Δpressure), vagal outflow (ΔR-R interval/Δdiameter), conventional integrated interval/Δpressure). Integrated was lower men than (6.8±1.2 versus...
The occurrence of a sustained vasodilation and hypotension after acute, dynamic exercise suggests that may alter arterial baroreflex mechanisms. Therefore, we assessed systemic hemodynamics, regulation heart rate, cardiac vagal tone 60 min cycling at 60% peak oxygen consumption in 12 healthy, untrained men women (ages 21-28 yr). We derived sigmoidal carotid-cardiac relations by measurement R-R interval changes induced ramped, stepwise, R-wave-triggered external neck pressure from 40 to -65...
Coronary heart disease (CHD) and cardiac sudden death (CSD) incidence accelerates after menopause, but the is lower in physically active versus less women. Low rate variability (HRV) a risk factor for CHD CSD. The purpose of present investigation was to test hypothesis that HRV at rest greater compared with postmenopausal If true, we further hypothesized women would be closely associated an elevated spontaneous baroreflex sensitivity (SBRS). (both time frequency domain measures) SBRS...