Open Access. Powered by Scholars. Published by Universities.®

Medical Biophysics Commons

Open Access. Powered by Scholars. Published by Universities.®

288 Full-Text Articles 581 Authors 74797 Downloads 31 Institutions

All Articles in Medical Biophysics

Faceted Search

288 full-text articles. Page 1 of 12.

Saturation And Response Dependence Of Oslds And Microstar Reader In The High Dose Range For Intrabeam Kv X-Rays And Initial Investigation Into The Use Of Gafchromic Film As An In Vivo Dosimeter In The High Dose Region, Travis Bryant 2017 Oregon Health & Science University

Saturation And Response Dependence Of Oslds And Microstar Reader In The High Dose Range For Intrabeam Kv X-Rays And Initial Investigation Into The Use Of Gafchromic Film As An In Vivo Dosimeter In The High Dose Region, Travis Bryant

Scholar Archive

No abstract provided.


Skeletal Muscle Fibrosis In The Mdx/Utrn+/- Mouse Validates Its Suitability As A Murine Model Of Duchenne Muscular Dystrophy, Lisa M. Hoffman, William T. Hrinivich, Kelly M. Gutpell 2017 Western University

Skeletal Muscle Fibrosis In The Mdx/Utrn+/- Mouse Validates Its Suitability As A Murine Model Of Duchenne Muscular Dystrophy, Lisa M. Hoffman, William T. Hrinivich, Kelly M. Gutpell

Lisa Hoffman

Various therapeutic approaches have been studied for the treatment of Duchenne muscular dystrophy (DMD), but none of these approaches have led to significant long-term effects in patients. One reason for this observed inefficacy may be the use of inappropriate animal models for the testing of therapeutic agents. The mdx mouse is the most widely used murine model of DMD, yet it does not model the fibrotic progression observed in patients. Other murine models of DMD are available that lack one or both alleles of utrophin, a functional analog of dystrophin. The aim of this study was to compare fibrosis and ...


Characterization Of A Far-Red Analog Of Ghrelin For Imaging Ghs-R In P19-Derived Cardiomyocytes., Gregory A F Douglas, Rebecca McGirr, Carlie L Charlton, Dov B Kagan, Lisa M Hoffman, Leonard G Luyt, Savita Dhanvantari 2017 Selected Works

Characterization Of A Far-Red Analog Of Ghrelin For Imaging Ghs-R In P19-Derived Cardiomyocytes., Gregory A F Douglas, Rebecca Mcgirr, Carlie L Charlton, Dov B Kagan, Lisa M Hoffman, Leonard G Luyt, Savita Dhanvantari

Lisa Hoffman

Ghrelin and its receptor, the growth hormone secretagogue receptor (GHS-R), are expressed in the heart, and may function to promote cardiomyocyte survival, differentiation and contractility. Previously, we had generated a truncated analog of ghrelin conjugated to fluorescein isothiocyanate for the purposes of determining GHS-R expression in situ. We now report the generation and characterization of a far-red ghrelin analog, [Dpr(3)(octanoyl), Lys(19)(Cy5)]ghrelin (1-19), and show that it can be used to image changes in GHS-R in developing cardiomyocytes. We also generated the des-acyl analog, des-acyl [Lys(19)(Cy5)]ghrelin (1-19) and characterized its binding to mouse ...


Use Of Imaging Biomarkers To Assess Perfusion And Glucose Metabolism In The Skeletal Muscle Of Dystrophic Mice, Nabeel Ahmad, Ian Welch, Robert Grange, Jennifer Hadway, Savita Dhanvantari, David Hill, Ting-Yim Lee, Lisa M Hoffman 2017 The University of Western Ontario

Use Of Imaging Biomarkers To Assess Perfusion And Glucose Metabolism In The Skeletal Muscle Of Dystrophic Mice, Nabeel Ahmad, Ian Welch, Robert Grange, Jennifer Hadway, Savita Dhanvantari, David Hill, Ting-Yim Lee, Lisa M Hoffman

Lisa Hoffman

BACKGROUND: Duchenne muscular dystrophy (DMD) is a severe neuromuscular disease that affects 1 in 3500 boys. The disease is characterized by progressive muscle degeneration that results from mutations in or loss of the cytoskeletal protein, dystrophin, from the glycoprotein membrane complex, thus increasing the susceptibility of contractile muscle to injury. To date, disease progression is typically assessed using invasive techniques such as muscle biopsies, and while there are recent reports of the use of magnetic resonance, ultrasound and optical imaging technologies to address the issue of disease progression and monitoring therapeutic intervention in dystrophic mice, our study aims to validate ...


Using Computed Tomography Perfusion To Evaluate The Blood-Brain-Barrier And Blood-Tumor-Barrier Response Following Focused Ultrasound Sonication With Microbubble Administration, Hassaan Ahmed 2017 The University of Western Ontario

Using Computed Tomography Perfusion To Evaluate The Blood-Brain-Barrier And Blood-Tumor-Barrier Response Following Focused Ultrasound Sonication With Microbubble Administration, Hassaan Ahmed

Electronic Thesis and Dissertation Repository

The blood-brain-barrier (BBB) is the single most limiting factor in the delivery of neurotherapeutics into the brain. Focused ultrasound sonication combined with intravenous microbubble administration (FUSwMB) is a novel technique that can transiently disrupt the BBB, with minimal vascular or tissue damage, allowing for localized drug delivery over the targeted region. The goals of this thesis are to: 1) use computed tomography (CT) perfusion to measure the permeability surface area product (PS) following USwMB in normal rabbits with an intact BBB, and 2) to evaluate the blood-tumor-barrier (BTB) PS response following FUSwMB in a C6 rat glioma model.


The Design, Fabrication, And Characterization Of Nanoparticle-Protein Interactions For Theranostic Applications, Wai Hei Tse 2017 The University of Western Ontario

The Design, Fabrication, And Characterization Of Nanoparticle-Protein Interactions For Theranostic Applications, Wai Hei Tse

Electronic Thesis and Dissertation Repository

Theranostics, a combination of therapeutics and diagnostics, spans a spectrum of research areas to provide new opportunities in developing new healthcare technologies and medicine at affordable prices. Through employing a personalized medicine approach, biotechnology can be tailored to the needs of an individual. Applications of theranostics include drug delivery carriers capable of sustained drug release and targeted delivery, biosensors with high sensitivity and selectivity, and diagnostic relevant entities that can be incorporated into the former technologies. Nanotechnology provides a suitable foundation for theranostics to build upon due to material-based properties; magnetism, biocompatibility, and quantum effects to name a few. Purpose ...


3d Ultrasound In The Management Of Post Hemorrhagic Ventricle Dilatation, Jessica Kishimoto 2017 The University of Western Ontario

3d Ultrasound In The Management Of Post Hemorrhagic Ventricle Dilatation, Jessica Kishimoto

Electronic Thesis and Dissertation Repository

Enlargement of the cerebral ventricles is relatively common among extremely preterm neonates born before 28 weeks gestational age. One common cause of ventricle dilatation is post hemorrhagic ventricle dilatation following a bleed in the cerebral ventricles. While many neonates with PHVD will have spontaneous resolution of the condition, severe, persistent PHVD is associated with a greater risk of brain injury and morbidity later in life and left untreated can cause death. The current clinical management strategy consists of daily measurements of head circumference and qualitative interpretation of two-dimensional US images to detect ventricular enlargement and monitoring vital signs for indications ...


Numerically Solving A System Of Pdes Modeling Chronic Wounds Treated With Oxygen Therapy, Stefan Stryker 2017 Western Kentucky University

Numerically Solving A System Of Pdes Modeling Chronic Wounds Treated With Oxygen Therapy, Stefan Stryker

Honors College Capstone Experience/Thesis Projects

Chronic wounds such as diabetic foot ulcers are the leading cause of non-traumatic amputations in developed countries. For researchers to better understand the physiology of these wounds, a mathematical model describing oxygen levels at the wound site can be used to help predict healing responses. The model utilizes equations that are modified from work by Guffey (2015) that consists of four variables – oxygen, bacteria, neutrophils, and chemoattractant within a system of partial differential equations. Our research focuses on numerically solving these partial differential equations using a finite volume approach. This numerical solver will be important for future research in optimization ...


A Proposed Framework For Consensus-Based Lung Tumour Volume Auto-Segmentation In 4d Computed Tomography Imaging., Spencer Martin, Mark Brophy, David Palma, Alexander V Louie, Edward Yu, Brian Yaremko, Belal Ahmad, John L Barron, Steven S Beauchemin, George Rodrigues, Stewart Gaede 2017 Selected Works

A Proposed Framework For Consensus-Based Lung Tumour Volume Auto-Segmentation In 4d Computed Tomography Imaging., Spencer Martin, Mark Brophy, David Palma, Alexander V Louie, Edward Yu, Brian Yaremko, Belal Ahmad, John L Barron, Steven S Beauchemin, George Rodrigues, Stewart Gaede

Edward Yu

This work aims to propose and validate a framework for tumour volume auto-segmentation based on ground-truth estimates derived from multi-physician input contours to expedite 4D-CT based lung tumour volume delineation. 4D-CT datasets of ten non-small cell lung cancer (NSCLC) patients were manually segmented by 6 physicians. Multi-expert ground truth (GT) estimates were constructed using the STAPLE algorithm for the gross tumour volume (GTV) on all respiratory phases. Next, using a deformable model-based method, multi-expert GT on each individual phase of the 4D-CT dataset was propagated to all other phases providing auto-segmented GTVs and motion encompassing internal gross target volumes (IGTVs ...


A Proposed Framework For Consensus-Based Lung Tumour Volume Auto-Segmentation In 4d Computed Tomography Imaging., Spencer Martin, Mark Brophy, David Palma, Alexander V Louie, Edward Yu, Brian Yaremko, Belal Ahmad, John L Barron, Steven S Beauchemin, George Rodrigues, Stewart Gaede 2017 Selected Works

A Proposed Framework For Consensus-Based Lung Tumour Volume Auto-Segmentation In 4d Computed Tomography Imaging., Spencer Martin, Mark Brophy, David Palma, Alexander V Louie, Edward Yu, Brian Yaremko, Belal Ahmad, John L Barron, Steven S Beauchemin, George Rodrigues, Stewart Gaede

Edward Yu

This work aims to propose and validate a framework for tumour volume auto-segmentation based on ground-truth estimates derived from multi-physician input contours to expedite 4D-CT based lung tumour volume delineation. 4D-CT datasets of ten non-small cell lung cancer (NSCLC) patients were manually segmented by 6 physicians. Multi-expert ground truth (GT) estimates were constructed using the STAPLE algorithm for the gross tumour volume (GTV) on all respiratory phases. Next, using a deformable model-based method, multi-expert GT on each individual phase of the 4D-CT dataset was propagated to all other phases providing auto-segmented GTVs and motion encompassing internal gross target volumes (IGTVs ...


In Vivo Magnetic Resonance Imaging Morphometry Measurements Of Pulmonary Airspace Enlargement, Eric J. Lessard 2017 The University of Western Ontario

In Vivo Magnetic Resonance Imaging Morphometry Measurements Of Pulmonary Airspace Enlargement, Eric J. Lessard

Electronic Thesis and Dissertation Repository

Diffusion-weighted magnetic resonance imaging (MRI) provides unparalleled information and measurements of lung structure and function without the burden of ionizing radiation. In particular, diffusion-weighted MRI provides estimates of airspace enlargement, which is a hallmark characteristic of emphysema. MRI provides a way to measure in vivo mean-linear-intercept (Lm) and this is a promising measurement for clinical evaluation of disease progression in patients with Alpha-1 Antitrypsin Deficiency (AATD) in which airspace enlargement begins early in life. As such, our objective was to evaluate MRI measurements of airspace enlargement in AATD patients and compare these measurements to ex-smokers with chronic obstructive pulmonary ...


Quantification Of Cerebral Blood Flow And Oxidative Metabolism In Infants With Post-Hemorrhagic Ventricular Dilatation, Peter McLachlan 2017 The University of Western Ontario

Quantification Of Cerebral Blood Flow And Oxidative Metabolism In Infants With Post-Hemorrhagic Ventricular Dilatation, Peter Mclachlan

Electronic Thesis and Dissertation Repository

Post-hemorrhagic ventricular dilatation (PHVD) is highly predictive of mortality and morbidity among very low birth weight preterm infants. Impaired cerebral blood flow (CBF) due to elevated intracranial pressure (ICP) is believed to be a contributing factor. In this study, a hyperspectral near-infrared spectroscopy (NIRS) method of measuring CBF and the cerebral metabolic rate of oxygen (CMRO2) was used to investigate perfusion and metabolism changes in patients receiving a ventricular tap (VT) based on clinical signs of elevated ICP. To improve measurement accuracy, the spectral analysis was modified to account for compression of the cortical mantle caused by PHVD and ...


Tools For Improving High-Dose-Rate Prostate Cancer Brachytherapy Using Three-Dimensional Ultrasound And Magnetic Resonance Imaging, William T. Hrinivich 2017 The University of Western Ontario

Tools For Improving High-Dose-Rate Prostate Cancer Brachytherapy Using Three-Dimensional Ultrasound And Magnetic Resonance Imaging, William T. Hrinivich

Electronic Thesis and Dissertation Repository

High-dose-rate brachytherapy (HDR-BT) is an interstitial technique for the treatment of intermediate and high-risk localized prostate cancer that involves placement of a radiation source directly inside the prostate using needles. Dose-escalated whole-gland treatments have led to improvements in survival, and tumour-targeted treatments may offer future improvements in therapeutic ratio. The efficacy of tumour-targeted HDR-BT depends on imaging tools to enable accurate dose delivery to prostate sub-volumes. This thesis is focused on implementing ultrasound tools to improve HDR-BT needle localization accuracy and efficiency, and evaluating dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for tumour localization.

First, we implemented a device enabling ...


Capacitive Memory Alters Alternans And Spontaneous Activity In A Minimal Cardiomyocyte Model, Tien Comlekoglu, Seth H. Weinberg 2017 Virginia Commonwealth University

Capacitive Memory Alters Alternans And Spontaneous Activity In A Minimal Cardiomyocyte Model, Tien Comlekoglu, Seth H. Weinberg

Biology and Medicine Through Mathematics Conference

No abstract provided.


High Performance Computation Of Cardiac Models In Real-Time Using Webgl, Abouzar Kaboudian, Flavio H. Fenton 2017 Georgia Institute of Technology

High Performance Computation Of Cardiac Models In Real-Time Using Webgl, Abouzar Kaboudian, Flavio H. Fenton

Biology and Medicine Through Mathematics Conference

No abstract provided.


Examination Of Noninvasive Alternatives To Blood Pressure Waveform Measurement In Preterm Infants, William E. Lawrence 2017 College of William and Mary

Examination Of Noninvasive Alternatives To Blood Pressure Waveform Measurement In Preterm Infants, William E. Lawrence

Undergraduate Honors Theses

Preterm infants are at an elevated risk for a number of medical conditions including shock. Continuous monitoring of the blood pressure (BP) waveform can allow for early detection of such conditions. However, BP is monitored invasively using an arterial catheter. To examine possible non-invasive alternatives, we used ECG, SPO2, and BP data collected from 14 infants at the neonatal intensive care unit (NICU) in Veldhoven, Holland. One hour's worth of data was randomly selected to analyze from the second and penultimate days of each baby's stay. Using the BP waveform together with the ECG, we calculated the R-peak ...


Unfair Competition Governs The Interaction Of Pcpi-17 With Myosin Phosphatase (Pp1-Mypt1)., Joshua J. Filter, Byron C. Williams, Masumi Eto, David Shalloway, Michael L. Goldberg 2017 Cornell University

Unfair Competition Governs The Interaction Of Pcpi-17 With Myosin Phosphatase (Pp1-Mypt1)., Joshua J. Filter, Byron C. Williams, Masumi Eto, David Shalloway, Michael L. Goldberg

Department of Molecular Physiology and Biophysics Faculty Papers

The small phosphoprotein pCPI-17 inhibits myosin light-chain phosphatase (MLCP). Current models postulate that during muscle relaxation, phosphatases other than MLCP dephosphorylate and inactivate pCPI-17 to restore MLCP activity. We show here that such hypotheses are insufficient to account for the observed rapidity of pCPI-17 inactivation in mammalian smooth muscles. Instead, MLCP itself is the critical enzyme for pCPI-17 dephosphorylation. We call the mutual sequestration mechanism through which pCPI-17 and MLCP interact inhibition by unfair competition: MLCP protects pCPI-17 from other phosphatases, while pCPI-17 blocks other substrates from MLCP's active site. MLCP dephosphorylates pCPI-17 at a slow rate that is ...


P27. Acute Impact Of An Extremely Low Frequency Magnetic Stimulus On Human Neurophysiological Function - Magnetophosphene Perception, Cadence M. Baker 2017 Western University

P27. Acute Impact Of An Extremely Low Frequency Magnetic Stimulus On Human Neurophysiological Function - Magnetophosphene Perception, Cadence M. Baker

Western Research Forum

Background: Magnetophosphenes are classified as colourless, flickering lights that are perceived with closed eyes in the dark, and upon exposure to a magnetic field (MF). Uncertainties exist involving the MF threshold for magnetophosphene perception.

Methods: Forty subjects will be enrolled in this experiment aiming to provide a frequency-response curve of magnetophosphene perception under MF exposure. Subjects will sit in a whole head MF exposure device wearing a 64-channel MRI-compatible EEG cap. Subjects will be exposed to a MF with a frequency of 5-300 Hz, in the form of an increasing flux density ramp (increasing magnetic field flux density from 0-100 ...


Diversity And Plasticity In Signaling Pathways That Regulate Smooth Muscle Responsiveness: Paradigms And Paradoxes For The Myosin Phosphatase, The Master Regulator Of Smooth Muscle Contraction., Masumi Eto, Toshio Kitazawa 2017 Thomas Jefferson University

Diversity And Plasticity In Signaling Pathways That Regulate Smooth Muscle Responsiveness: Paradigms And Paradoxes For The Myosin Phosphatase, The Master Regulator Of Smooth Muscle Contraction., Masumi Eto, Toshio Kitazawa

Department of Molecular Physiology and Biophysics Faculty Papers

A hallmark of smooth muscle cells is their ability to adapt their functions to meet temporal and chronic fluctuations in their demands. These functions include force development and growth. Understanding the mechanisms underlying the functional plasticity of smooth muscles, the major constituent of organ walls, is fundamental to elucidating pathophysiological rationales of failures of organ functions. Also, the knowledge is expected to facilitate devising innovative strategies that more precisely monitor and normalize organ functions by targeting individual smooth muscles. Evidence has established a current paradigm that the myosin light chain phosphatase (MLCP) is a master regulator of smooth muscle responsiveness ...


Mri-Based Susceptibility Mapping For In-Vivo Iron And Blood Oximetry Measurements, Hannah Erdevig 2017 University of Colorado, Boulder

Mri-Based Susceptibility Mapping For In-Vivo Iron And Blood Oximetry Measurements, Hannah Erdevig

Undergraduate Honors Theses

MRI is increasingly used in mapping tissue susceptibility to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease [1,2]. Accurate measurement is important for determining oxygen and iron content in blood vessels and tissue in the brain, which are in turn used for noninvasive clinical diagnosis and treatment assessments. Magnetic field distortions with a resolution of a few parts per billion can be measured using MRI phase maps. The field distortion map can then be inverted to obtain a quantitative susceptibility map. The primary ...


Digital Commons powered by bepress