A5062570585- Hemoglobinopathies and Related Disorders
- Heart Rate Variability and Autonomic Control
- Iron Metabolism and Disorders
- Neuroscience of respiration and sleep
- Non-Invasive Vital Sign Monitoring
- Obstructive Sleep Apnea Research
- Neurological and metabolic disorders
- Neonatal and fetal brain pathology
- Biochemical effects in animals
- ECG Monitoring and Analysis
- Neonatal Health and Biochemistry
- Heme Oxygenase-1 and Carbon Monoxide
- Erythrocyte Function and Pathophysiology
- Optical Imaging and Spectroscopy Techniques
- Bone and Joint Diseases
- Myeloproliferative Neoplasms: Diagnosis and Treatment
- Quality and Safety in Healthcare
- Cardiovascular Disease and Adiposity
- Sleep and Work-Related Fatigue
- Climate Change and Health Impacts
- Infrared Thermography in Medicine
- Receptor Mechanisms and Signaling
- Thermoregulation and physiological responses
- Hemoglobin structure and function
- Healthcare Technology and Patient Monitoring
Carnegie Mellon University
2020-2024
University of Southern California
2011-2023
Viterbo University
2017-2019
Children's Hospital of Los Angeles
2014
Vaso-occlusive crisis (VOC) is a hallmark of sickle cell disease (SCD) and occurs when deoxygenated sickled red blood cells occlude the microvasculature. Any stimulus, such as mental stress, which decreases microvascular flow will increase likelihood entrapment resulting in local vaso-occlusion progression to VOC. Neurally mediated vasoconstriction might be physiological link between triggers vaso-occlusion. In this study, we determined effect stress on autonomic nervous system reactivity....
The painful vaso-occlusive crises (VOC) that characterize sickle cell disease (SCD) progress over hours from the asymptomatic steady-state. SCD patients report VOC can be triggered by stress, cold exposure, and, pain itself. We anticipated could cause neural-mediated vasoconstriction, decreasing regional blood flow and promoting entrapment of cells in microvasculature. Therefore, we measured microvascular fingers both hands using plethysmography laser-Doppler flowmetry while applying a...
Painful vaso-occlusive crisis (VOC), a complication of sickle cell disease (SCD), occurs when sickled red blood cells obstruct flow in the microvasculature. We postulated that exaggerated sympathetically mediated vasoconstriction, endothelial dysfunction and synergistic interaction between these two factors act together to reduce microvascular flow, promoting regional vaso-occlusions, setting stage for VOC. previously found SCD subjects had stronger vasoconstriction response pulses...
Sickle cell disease (SCD) is a genetic disorder of hemoglobin producing hemoglobin-S (HbS) and resulting in recurrent severe episodes pain, organ damage premature death due to vaso- occlusion. Deoxy HbS polymerizes, causing red cells become rigid lodge the microvasculature if they do not escape into larger vessels before this transformation occurs. The mechanism that triggers transition from steady state vaso-occlusive crisis (VOC) known. Patients cold, emotional stress, pain itself can...
Abstract We have previously demonstrated that sickle cell disease (SCD) patients maintain normal global systemic and cerebral oxygen delivery by increasing cardiac output. However, ischemic end‐organ injury remains common suggesting tissue may be impaired microvascular dysregulation or damage. To test this hypothesis, we performed fingertip laser Doppler flowmetry measurements at the base of nailbed regional saturation (rSO 2 ) on dorsal surface same hand. This was done during flow mediated...
In sickle cell disease (SCD), prolonged capillary transit times, resulting from reduced peripheral blood flow, increase the likelihood of rigid red cells entrapment in microvasculature, predisposing to vaso-occlusive crisis. Since changes flow are mediated by autonomic nervous system (ANS), we tested hypothesis that cardiac and vascular responses head-up tilt (HUT) abnormal SCD. Heart rate, respiration, non-invasive continuous pressure finger photoplethysmogram (PPG) were monitored before,...
Obstructive sleep apnea (OSA) involves the interplay of several different factors such as an unfavorable upper airway anatomy, deficiencies in pharyngeal muscle responsiveness, a low arousal threshold, and ventilatory control instability. Although stability has been extensively studied adults, little is known about its characteristics pediatric population. In this study, we developed novel experimental setup that allowed us to perturb respiratory system during natural non-rapid eye movement...
Alpha thalassemia is a hemoglobinopathy due to decreased production of the α-globin protein from loss up four genes, with one or two missing in trait phenotype. Individuals sickle cell disease who co-inherit genes have been known reduced risk morbid outcomes, but underlying mechanism unknown. While gene deletions affect red deformability, and are also present endothelial wall human arterioles participate nitric oxide scavenging during vasoconstriction. Decreased α-thalassemia may thereby...
Sickle cell disease (SCD) is characterized by sudden onset of painful vaso-occlusive crises (VOC), which occur on top the underlying chronic blood disorder. The mechanisms that trigger VOC remain elusive, but recent work suggests autonomic dysfunction may be an important predisposing factor. Heart-rate variability has been employed in previous studies, derived indices have provided only limited univariate information about cardiovascular control SCD. To circumvent this limitation, a...
Sickle cell disease (SCD) is a monogenic hemoglobinopathy associated with significant morbidity and mortality. Cardiopulmonary, vascular sudden death are the reasons for majority of young adult mortality in SCD. To better understand clinical importance multi-level dysfunction, 2009 we assessed cardiac function including tricuspid regurgitant jet velocity (TRV), tissue systole(S') diastole (E'), inflammatory, rheologic hemolytic biomarkers as predictors patients With up to 9 years follow up,...
Short-term blood pressure variability is generally attributed to the baroreflex feedback control on heart rate and systemic vascular resistance (SVR), mechanical effect of respiration stroke volume. Although it known that affects sympathetic outflow deep breaths can lead peripheral vasoconstriction, respiratory modulation SVR has been little studied. In present study, we investigated dynamics resulting from its by employing structured minimal modeling approaches. Using arterial tonometry as...
Spectral analysis of heart rate variability (HRV) is commonly employed to track changes in autonomic nervous system and respiratory activity during sleep. However, conventional HRV spectral indices can be seriously confounded by inter-subject differences or intra-individual ventilation ventilatory pattern, especially subjects with obstructive sleep apnea syndrome (OSAS). We highlight the approach we have undertaken circumvent this problem introducing "respiration-adjusted" HRV. Since...
The purpose of this work was to noninvasively detect and quantify microvascular blood flow changes in response externally applied pain humans. responsiveness the microvasculature stimulation might serve as an objective biomarker diseases associated with altered perception dysregulated vascular functions. availability such a may be useful tool for predicting outcome treatments, particularly like sickle cell anemia where clinical manifestations are directly linked perfusion. We, therefore,...
Transient increases in peripheral vasoconstriction frequently occur obstructive sleep apnea and periodic leg movement disorder, both of which are common sickle cell disease (SCD). These events reduce microvascular blood flow increase the likelihood triggering painful vaso-occlusive crises (VOC) that hallmark SCD. We recently reported a significant association between magnitude vasoconstriction, inferred from finger photoplethysmogram (PPG) during sleep, frequency future VOC 212 children with...
Deep breaths akin to sighs have been reported cause peripheral vasoconstriction. Our previous simulation studies shown that this phenomenon cannot be reproduced in existing circulatory control models without inclusion of a respiratory-vascular coupling mechanism. To better understand "sigh-vasoconstriction reflex", we investigated the effect spontaneous and passively induced as well breathing on vasoconstriction during wakefulness non-rapid eye movement sleep human subjects. We found both...
The basic model of SCD physiology states that vaso-occlusion occurs when hemoglobin S-containing red blood cells (RBC) undergo sickling before they escape the capillary into a larger vessel. We have shown mental stress, pain and cold, events reported by patients to trigger vaso-occlusive crisis (VOC), cause rapid significant decrease in flow, reducing likelihood RBC could transit microvasculature occurs. However, critical link between microvascular flow incidence future sickle VOC has never...
The peripheral vascular resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PV</sub> ) control is known to be largely sympathetically-mediated; thus assessment of the R would allow us infer valuable information regarding sympathetic nervous activity. linear and 2nd-order nonlinear minimal models were used capture influences blood pressure (baroreflex) respiration (respiratory-coupling) on fluctuations . To validate models, they applied...
Abstract There has been no shortage of discussion about artificial intelligence and machine learning (ML) in the past decade. ML healthcare is becoming more widely used potential impact on disease prevention diagnosis. With growing interest among biomedical engineering students, this work outlines development an introductory course for (BME) graduate students. The introduces high-level concepts behind algorithms teaches students which are best suited to different kinds biomedical-related...