A5013452094- Chronic Obstructive Pulmonary Disease (COPD) Research
- Asthma and respiratory diseases
- Inhalation and Respiratory Drug Delivery
- Respiratory Support and Mechanisms
- Cellular Mechanics and Interactions
- Elasticity and Material Modeling
- Microfluidic and Bio-sensing Technologies
- Atomic and Subatomic Physics Research
- 3D Printing in Biomedical Research
- Spaceflight effects on biology
- Respiratory and Cough-Related Research
- Allergic Rhinitis and Sensitization
- Phonocardiography and Auscultation Techniques
- Tracheal and airway disorders
- Acoustic Wave Resonator Technologies
- Obstructive Sleep Apnea Research
- Force Microscopy Techniques and Applications
- Cardiovascular Function and Risk Factors
- Advanced Chemical Sensor Technologies
- Neonatal Respiratory Health Research
- Cystic Fibrosis Research Advances
- Blood properties and coagulation
- Exercise and Physiological Responses
- Mechanical Circulatory Support Devices
- Cell Adhesion Molecules Research
Dalhousie University
2015-2024
University of Toronto
2006
University of Ottawa
2006
McGill University
1994-2005
Christie (Canada)
1994-2005
Harvard University
1998-1999
Royal Victoria Hospital
1994
Victoria General Hospital
1992
We report a scaling law that governs both the elastic and frictional properties of wide variety living cell types, over range time scales under biological interventions. This identifies these cells as soft glassy materials existing close to glass transition, implies cytoskeletal proteins may regulate mechanical mainly by modulating effective noise temperature matrix. The practical implications are is an easily quantified measure ability cytoskeleton deform, flow, reorganize.
Oscillometry (also known as the forced oscillation technique) measures mechanical properties of respiratory system (upper and intrathoracic airways, lung tissue chest wall) during quiet tidal breathing, by application an oscillating pressure signal (input or forcing signal), most commonly at mouth. With increased clinical research use, it is critical that all technical details hardware design, processing analyses, testing protocols are transparent clearly reported to allow standardisation,...
In dealing with systems as complex the cytoskeleton, we need organizing principles or, short of that, an empirical framework into which these fit. We report here unexpected invariants cytoskeletal behavior that comprise such framework. measured elastic and frictional moduli a variety cell types over wide range time scales using biological interventions. all instances stresses dominated at frequencies below 300 Hz, increased only weakly frequency, followed power law; no characteristic scale...
Purpose To compare hyperpolarized helium‐3 ( 3 He) and xenon‐129 129 Xe) MRI in asthmatics before after salbutamol inhalation. Materials Methods Seven provided written informed consent underwent spirometry, plethysmography, He Xe ventilation defect percent (VDP) coefficient of variation (COV) were measured. characterize the airways spatially related to defects, wall area (WA%) lumen (LA) evaluated for two subjects who had thoracic x‐ray computed tomography (CT) acquired 1 year MRI. Results...
Histologic stains have been used as the gold standard to visualize extracellular matrix (ECM) changes associated with airway remodeling in asthma, yet they provide no information on biochemical and structural characteristics of ECM, which are vital understanding alterations tissue function.
We investigated the rheological properties of living human airway smooth muscle cells in culture and monitored changes induced by exogenous stimuli. oscillated small magnetic microbeads bound specifically to integrin receptors computed storage modulus (G′) loss (G") from applied torque resulting rotational motion beads as determined their remanent field. Under baseline conditions, G′ increased weakly with frequency, whereas G" was independent frequency. The cell predominantly elastic, ratio...
Magnetic twisting cytometry (MTC) (Wang N, Butler JP, and Ingber DE, Science260: 1124–1127, 1993) is a useful technique for probing cell micromechanics. The based on ligand-coated magnetic microbeads bound to membrane receptors measuring the resulting bead rotation with magnetometer. Owing low signal-to-noise ratio, however, signal must be modulated, which accomplished by spinning sample at ∼10 Hz. Present demodulation approaches limit MTC range frequencies <0.5 We propose novel algorithm...
Alveolar epithelial cells undergo stretching during breathing and mechanical ventilation. Stretch can modify cell viscoelastic properties, which may compromise the balance of forces in alveolar epithelium. We studied viscoelasticity (A549) subjected to equibiaxial distention with a novel experimental approach. Cells were cultured on flexible substrates stepwise deformations up 17% device built an inverted microscope. Simultaneously, storage (G') loss (G'') moduli measured (0.1-100 Hz)...
Maksym, Geoffrey N., and Jason H. T. Bates. A distributed nonlinear model of lung tissue elasticity. J. Appl. Physiol. 82(1): 32–41, 1997.—- We present a theory relating the static stress-strain properties strips to stress-bearing constituents, collagen elastin. The fiber pair is modeled as Hookean spring (elastin) in parallel with string element (collagen), which extends maximum stop length. Based on series pairs, we develop both analytical numerical models constituent that account for were...
We hypothesized that short-term variation in airway caliber could be quantified by frequency distributions of respiratory impedance (Zrs) measured at high frequency. Zrs 6 Hz forced oscillations during quiet breathing for 15 min 10 seated asthmatic patients and normal subjects upright supine positions before after methacholine (MCh). plotted calculated means, skewness, kurtosis, significance differences between log-normal distributions. The data were close to, but usually significantly...
Mechanical stress (MS) causes cytoskeletal (CSK) and phenotypic changes in cells. Such airway smooth muscle (ASM) cells might contribute to the pathophysiology of asthma. We have shown that periodic mechanical strain applied cultured ASM alters structure expression CSK proteins increases cell stiffness contractility (Smith PG, Moreno R, Ikebe M. Am J Physiol Lung Cell Mol 272: L20-L27, 1997; Smith Deng L, Fredberg JJ, Maksym GN. 285: L456-L463, 2003). However, mechanically induced changes,...
We tested the hypothesis that cytoskeletal reorganization induced by cyclic strain increases stiffness (G′). G′ was measured optical magnetic twisting cytometry in control cells and had received mechanical for 10–12 days. before after both contractile relaxant agonists, strained parallel (Para) perpendicular (Perp) to aligned cytoskeleton. Before activation, Para 24 ± 5% (± SE) greater compared with Perp ( P < 0.05), 35% 6 (Cont, 0.01). The difference between enhanced KCl, increasing 171...
We measured tracheal pressure (Ptr) and flow (V) in open-chest anesthetized paralyzed dogs. The lungs were maintained at a fixed volume (initial positive end-expiratory 0.5 kPa) for 80 s while small-amplitude oscillations V 1 6 Hz applied simultaneously the opening. A bolus of histamine was given intravenously start oscillation period. time course lung elastic recoil (Pel) obtained by passing running average over Ptr to smooth out its oscillations. themselves separated into their 1- 6-Hz...
Airway smooth muscle (ASM) cellular and molecular biology is typically studied with single-cell cultures grown on flat 2D substrates. However, cells in vivo exist as part of complex 3D structures, it well established other cell types that altering substrate geometry exerts potent effects phenotype function. These factors may be especially relevant to asthma, a disease characterized by structural remodeling the airway wall, highlights need for more physiologically models ASM We utilized...
ABSTRACT Background and objective: Spirometry is insensitive to small airway abnormalities in asthma. Our objective was evaluate regional lung structure function using hyperpolarized 3 He magnetic resonance imaging (MRI) before, during after a methacholine challenge (MCh). Methods: Twenty‐five asthmatics (mean age = 34 ± 11 years) eight healthy volunteers (HV) 33 underwent spirometry, plethysmography MRI prior MCh. repeated following the MCh again 25 min salbutamol administration. gas...
Ventilation heterogeneity is a hallmark finding in obstructive lung disease and may be evaluated using variety of methods, including multiple-breath gas washout pulmonary imaging. Such methods provide an opportunity to better understand the relationships between structural functional abnormalities lungs, their with important clinical outcomes. We measured ventilation respiratory impedance 100 subjects [50 patients asthma, 22 ex-smokers, 28 chronic (COPD)] oscillometry hyperpolarized 3He...
Developed over six decades ago, pulmonary oscillometry has re-emerged as a noninvasive and effort-independent method for evaluating respiratory-system impedance in patients with obstructive lung disease. Here, we evaluated the relationships between hyperpolarized 3He ventilation-defect-percent (VDP) resistance, reactance area (AX) measurements 175 participants including 42 never-smokers without respiratory disease, 56 ex-smokers chronic-obstructive-pulmonary-disease (COPD), 28 COPD 49...
Abstract In asthma, the airway epithelium has an impaired capacity to differentiate and plays a key role in development of inflammation remodeling through mediator release. The study objective was investigate release (IL)-1 family members from primary epithelial-cells during differentiation, how they affect fibroblast (PAF)-induced inflammation, extracellular matrix (ECM) production, collagen I remodeling. IL-1α/β IL-33 epithelial differentiation assessed over 20-days using air-liquid...