A5000034832- Heart Rate Variability and Autonomic Control
- Spaceflight effects on biology
- Traumatic Brain Injury and Neurovascular Disturbances
- High Altitude and Hypoxia
- Optical Imaging and Spectroscopy Techniques
- Non-Invasive Vital Sign Monitoring
- Cardiovascular and Diving-Related Complications
- Anesthesia and Sedative Agents
- Thermoregulation and physiological responses
- Cardiovascular and exercise physiology
- Cardiovascular Syncope and Autonomic Disorders
- Neuroscience of respiration and sleep
- Anesthesia and Neurotoxicity Research
- Respiratory Support and Mechanisms
- Anesthesia and Pain Management
- Hemodynamic Monitoring and Therapy
- Cerebrospinal fluid and hydrocephalus
- Sleep and Work-Related Fatigue
- Health and Wellbeing Research
- Gastric Cancer Management and Outcomes
- EEG and Brain-Computer Interfaces
- Bone health and treatments
- Climate Change and Health Impacts
- Cardiac, Anesthesia and Surgical Outcomes
- Horticultural and Viticultural Research
Nihon University
2014-2024
Kashiwa Municipal Hospital
2024
Osaka Metropolitan University
2023
Johns Hopkins Medicine
2019
Johns Hopkins University
2019
The University of Texas Southwestern Medical Center
2000-2010
Institute for Exercise and Environmental Medicine
2001-2010
Texas Health Dallas
2001-2010
Marymount University
2008
Southwestern Medical Center
2002-2006
The purpose of the present study was to determine role autonomic neural control dynamic cerebral autoregulation in humans.We measured arterial pressure and blood flow (CBF) velocity 12 healthy subjects (aged 29+/-6 years) before after ganglion blockade with trimethaphan. CBF middle artery using transcranial Doppler. magnitude spontaneous changes mean were quantified by spectral analysis. transfer function gain, phase, coherence between these variables estimated quantify autoregulation. After...
Occupational or recreational exercise reduces mortality from cardiovascular disease. The potential mechanisms for this reduction may include changes in blood pressure (BP) and autonomic control of the circulation. Therefore, we conducted present long-term longitudinal study to quantify dose-response relationship between volume intensity training, regulation heart rate (HR) BP. We measured steady-state hemodynamics analyzed dynamic by spectral transfer function analysis variability 11...
Orthostatic intolerance is common when astronauts return to Earth: after brief spaceflight, up two‐thirds are unable remain standing for 10 min. Previous research suggests that susceptible individuals increase their systemic vascular resistance and plasma noradrenaline concentrations above pre‐flight upright levels. In this study, we tested the hypothesis adaptation microgravity of space impairs sympathetic neural responses posture on Earth. We studied six ∼72 23 days before landing day 16...
Exposure to microgravity alters the distribution of body fluids and degree distension cranial blood vessels, these changes in turn may provoke structural remodelling altered cerebral autoregulation. Impaired autoregulation has been documented following weightlessness simulated by head-down bed rest humans, is proposed as a mechanism responsible for postspaceflight orthostatic intolerance. In this study, we tested hypothesis that spaceflight impairs We studied six astronauts approximately 72...
1alpha,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], a vitamin D receptor (VDR) ligand, regulates calcium homeostasis and also exhibits noncalcemic actions on immunity cell differentiation. In addition to disorders of bone metabolism, VDR ligands are potential therapeutic agents in the treatment immune disorders, microbial infections, malignancies. Hypercalcemia, major adverse effect derivatives, limits their clinical application. The secondary bile acid lithocholic (LCA) is an additional...
Adaptation to head-down-tilt bed rest leads an apparent abnormality of baroreflex regulation cardiac period. We hypothesized that this “deconditioning response” could primarily be a result hypovolemia, rather than unique adaptation the autonomic nervous system rest. To test hypothesis, nine healthy subjects underwent 2 wk −6° head-down One year later, five these same acute hypovolemia with furosemide produce reductions in plasma volume observed after took advantage power spectral and...
Spontaneous blood pressure (BP) and R‐R variability are used frequently as ‘windows’ into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated role autonomic neural activity versus other ‘non‐neural’ factors in BP humans. Beat‐to‐beat BP, interval respiratory excursions were recorded ten healthy subjects (aged 30 ± 6 years) before after blockade trimethaphan. The spectral power...
Aging results in marked abnormalities of cardiovascular regulation. Regular exercise can improve many these age-related abnormalities. However, it remains unclear how much is optimal to achieve this improvement or whether the elderly ever autonomic control by training a degree similar that observed healthy young individuals. Ten sedentary seniors [71 +/- 3 (SD) yr] trained for 12 mo; involved progressive increases volume and intensity. Static hemodynamics were measured, R-wave-R-wave...
To reveal subtle morphological changes in the eye during simulated microgravity for spaceflights, we measured subfoveal choroidal thickness and foveal retinal 10 degrees head-down tilt (HDT). We hypothesized that elevated ophthalmic vein pressure increases via enlargement of vasculature greater blood volume.The right eyes nine healthy subjects (seven men, two women) were examined. Subfoveal using spectral domain-optical coherence tomography sitting position, after 15 30 min HDT. Intraocular...
The insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) in human synovial fluid play an important role maintaining articular cartilage metabolism. In this study we measured the concentrations of IGF-I, IGF-II, IGFBP-3 normal by RIA characterized IGFBPs Western ligand blot (WLB), immunoblot, immunoprecipitation. We also extended compared to fluids from patients with osteoarthritis (OA) rheumatoid arthritis (RA). were 19 +/- 3 (mean SE), 194 14, 349 65 ng/mL, respectively. OA,...
Astronauts returning to Earth have reduced orthostatic tolerance and exercise capacity. Alterations in autonomic nervous system neuromuscular function after spaceflight might contribute this problem. In study, we tested the hypothesis that exposure microgravity impairs neural control of sympathetic outflow response peripheral afferent stimulation produced by handgrip a cold pressor test humans. We studied five astronauts ≈72 23 days before, on landing day 16 Neurolab (STS‐90) space shuttle...
PTH-related protein (PTHrP) is produced in vascular smooth muscle, where it believed to act as a local vasorelaxant by activating either the classical PTH or unique PTHrP receptor. We used newly cloned complementary DNA encoding rat PTH/PTHrP receptor study expression of its messenger RNA (mRNA) primary aortic muscle cells (VSMC) and UMR-106 osteoblast-like under basal conditions response treatment with agonists. Both cell types expressed 2.4-kilobase mRNA transcript exhibited...
Although midazolam and propofol reduce cerebral blood flow (CBF) similarly, they generate different effects on the autonomic nervous system endothelium-induced relaxation. Midazolam induces sympathetic dominance, whereas parasympathetic dominance. has no effect endothelium-dependent relaxation, suppresses Moreover, apparently constricts arterioles. We therefore hypothesized that have dynamic autoregulation.Ten healthy male subjects received midazolam, propofol, placebo administrations in a...
Adaptation to spaceflight or head-down-tilt bed rest leads hypovolemia and an apparent abnormality of baroreflex regulation cardiac period. In a previous study, we demonstrated that both chronic (2 wk) acute induced led similar impairments in spontaneous control period, suggesting reduction plasma volume may be responsible for this after rest. Therefore hypothesized reduced "baroreflex function" could restored by intravenous infusion equivalent the Six healthy subjects underwent 2 wk -6...
Frequent changes in the perioperative central blood volume could affect cerebral autoregulation through alterations sympathetic nerve activity, cardiac output, viscosity, and vasomotor tone. However, effect of dynamic has not been studied during acute wide-ranging volume, especially with respect to hypervolemia hemodilution.We evaluated hypovolemia hemodilution using spectral transfer function analysis between mean arterial pressure (MBP) flow (CBF) velocity variability 12 individuals. Rapid...
Key points During long‐duration spaceflights, some astronauts develop structural ocular changes including optic disc oedema that resemble signs of intracranial hypertension. In the present study, pressure was estimated non‐invasively (nICP) using a model‐based analysis cerebral blood velocity and arterial waveforms in 11 before after spaceflights. Our results show group‐averaged estimates nICP decreased significantly nine without oedema, suggesting cephalad fluid shift during spaceflight...
Acute hypoxia directly causes cerebral arteriole vasodilation and also stimulates peripheral chemoreceptors to change autonomic neural activity. These changes may alter vascular modulation. We therefore hypothesized that dynamic autoregulation would be altered during acute exposure hypoxia. Fifteen healthy men were examined under normoxic (21%) hypoxic conditions. Oxygen concentrations decreased in stepwise fashion 19%, 17%, 15%, for 10 mins at each level. Mean blood pressure (MBP) the...
Background Dexmedetomidine, which is often used in intensive care units patients with compromised circulation, might induce further severe decreases cerebral blood flow (CBF) temporal arterial pressure induced by various stimuli if dynamic autoregulation not improved. Therefore, the authors hypothesized that dexmedetomidine strengthens autoregulation. Methods Fourteen healthy male subjects received placebo, low-dose (loading, 3 microg x kg(-1) h(-1) for 10 min; maintenance, 0.2 60 min), and...
Cerebral blood flow (CBF) increases and dynamic cerebral autoregulation is impaired by acute hypoxia. We hypothesized that progressive hypocapnia with restoration of arterial oxygen content after altitude acclimatization would normalize CBF autoregulation. To test this hypothesis, was examined spectral transfer function analyses between pressure velocity variabilities in 11 healthy members the Danish High-Altitude Research Expedition during normoxia hypoxia (10.5% O(2)) at sea level, (for...