Medicine and Health Sciences Commons^™

Development Of A Translational Animal Model Of Sepsis, Nathaniel E. Hayward

Electronic Thesis and Dissertation Repository

Sepsis is an excessive inflammatory response to infection that leads to multiple organ failure. The high mortality rates in the intensive care unit have remained stagnant, which can be attributed to the disconnect between the bench and the bedside. There is a global need for an animal model of sepsis that is more relevant to the clinical scenario. We developed an in vivo rat model of sepsis, with a high level of instrumentation, to monitor macrovascular and microvascular changes over the course of a feces-induced peritonitis (FIP) .

In addition, early fluid resuscitation of septic patients is associated with better …

Effects Of A Power-Line Frequency Magnetic Field On Human Cognitive Processing, Michael Corbacio

Electronic Thesis and Dissertation Repository

Extremely low frequency (ELF, < 300 Hz) magnetic fields (MFs) have been reported to modulate human cognitive performance. However, little research has investigated MF exposures comparable to the highest levels experienced in some occupations. This research evaluated the impact of a 60 Hz, 3 mT MF on human cognitive performance. Ninety-nine participants completed the double-blind protocol performing a selection of psychometric tests under two consecutive MF exposure conditions (exposure vs. no exposure). A significant interaction effect on a working memory test (digit span forward - F=5.21, p

Scanned Ion Beam Therapy For Thoracic Tumors, John Gordon Eley

Dissertations & Theses (Open Access)

Although frequently cured of Hodgkin lymphoma, adolescents and young adults can develop radiation induced second cancers. These patients could potentially benefit from scanned ion radiotherapy yet likely would require motion mitigation strategies. In theory, four-dimensional (4D) optimization of ion beam fields for individual motion states of respiration can enable superior sparing of healthy tissue near moving targets, compared to other motion mitigation strategies. Furthermore, carbon-ion therapy can sometimes provide greater relative biological effectiveness (RBE) for cell sterilization in a target but nearly equivalent RBE in tissue upstream of the target, compared to proton therapy. Thus, we expected that for some …

Investigation Of Respiratory Motion Management Techniques For Proton And Photon Radiotherapy Of Lung Cancer, Jason E. Matney

Dissertations & Theses (Open Access)

Protons as a source of therapeutic radiation can provide a substantial improvement over dose distributions that can be achieved with conventional sources of radiation such as high-energy photons. However, respiratory motion can significantly impact the delivered proton and photon dose distributions during lung cancer radiotherapy. The goals of this dissertation research were to evaluate the impact of respiratory motion and to estimate the benefit of respiratory gating for passively scattered proton therapy (PSPT) and intensity modulated photon therapy (IMRT).

The first aim of this project was to determine the impact of respiratory motion in PSPT and IMRT. Four dimensional dose …

One, Two And Three-Dimensional Ultrasound Measurements Of Carotid Atherosclerosis Before And After Cardiac Rehabilitation: Preliminary Results Of A Randomized Controlled Trial., Tamas J Lindenmaier, Daniel N Buchanan, Damien Pike, Tim Hartley, Robert D Reid, J David Spence, Richard Chan, Michael Sharma, Peter L Prior, Neville Suskin, Grace Parraga

Medical Biophysics Publications

BACKGROUND: It is still not known how patients who are post-transient ischemic attack (TIA) or post-stroke might benefit from prospectively planned comprehensive cardiac rehabilitation (CCR). In this pilot evaluation of a larger ongoing randomized-controlled-trial, we evaluated ultrasound (US) measurements of carotid atherosclerosis in subjects following TIA or mild non-disabling stroke and their relationship with risk factors before and after 6-months of CCR.

METHODS: Carotid ultrasound (US) measurements of one-dimensional intima-media-thickness (IMT), two-dimensional total-plaque-area (TPA), three-dimensional total-plaque-volume (TPV) and vessel-wall-volume (VWV) were acquired before and after 6-months CCR for 39 subjects who had previously experienced a TIA and provided written informed …

A Miniaturised Spectrometer Device For The Detection Of Nitrogen Dioxide In An Urban Environment, Brian Devine

Doctoral

Monitoring of air pollutants, such as Nitrogen Dioxide (NO2), that are toxic or environmentally damaging is a key metric for environmental protection agencies worldwide. There is a constant need to develop new technologies and methodologies that provide real-time, low cost pollution measurements over a broad range of sampling sites, particularly in urban and industrial areas. Typically, detection of pollutants in urban environments is performed using a variety of techniques, many of which are expensive, require complex setups and are in fixed locations. The novel system presented in this thesis is designed for portable, low cost and in-situ detection of pollutants …

The Impact Of Lateral Electron Disequilibrium On Stereotactic Body Radiation Therapy Of Lung Cancer, Brandon Disher

Electronic Thesis and Dissertation Repository

Stereotactic Body Radiation Therapy (SBRT) is an effective treatment option for patients with inoperable early-stage lung cancer. SBRT uses online image-guidance technology [e.g. cone-beam CT (CBCT)] to focus small-fields of high energy x-rays onto a tumour to deliver ablative levels of radiation dose (e.g. 54 Gy) in a few treatment fractions (e.g. 3). For the combination of these treatment parameters and a low density lung, lateral electron disequilibrium (LED) can potentially occur, reducing lung and tumour doses. The goal of this thesis was to determine the impact of LED on stereotactic body radiation therapy for lung cancer.

The effect of …

Evaluation Of Presage® Dosimeters For Brachytherapy Sources And The 3d Dosimetry And Characterization Of The New Agx100 125i Seed Model, Olivia Huang

Dissertations & Theses (Open Access)

With continuous new improvements in brachytherapy source designs and techniques, method of 3D dosimetry for treatment dose verifications would better ensure accurate patient radiotherapy treatment. This study was aimed to first evaluate the 3D dose distributions of the low-dose rate (LDR) Amersham 6711 Oncoseed^TM using PRESAGE^® dosimeters to establish PRESAGE^® as a suitable brachytherapy dosimeter. The new AgX100 ¹²⁵I seed model (Theragenics Corporation) was then characterized using PRESAGE^® following the TG-43 protocol.

PRESAGE^® dosimeters are solid, polyurethane-based, 3D dosimeters doped with radiochromic leuco dyes that produce a linear optical density response to radiation dose. …

Progression Of Carotid Plaque Volume Predicts Cardiovascular Events, Thapat Wannarong, Grace Parraga, Daniel Buchanan, Aaron Fenster, Andrew A House, Daniel G Hackam, J David Spence

Medical Biophysics Publications

BACKGROUND AND PURPOSE: Carotid ultrasound evaluation of intima-media thickness (IMT) and plaque burden has been used for risk stratification and for evaluation of antiatherosclerotic therapies. Increasing evidence indicates that measuring plaque burden is superior to measuring IMT for both purposes. We compared progression/regression of IMT, total plaque area (TPA), and total plaque volume (TPV) as predictors of cardiovascular outcomes.

METHODS: IMT, TPA, and TPV were measured at baseline in 349 patients attending vascular prevention clinics; they had TPA of 40 to 600 mm(2) at baseline to qualify for enrollment. Participants were followed up for ≤5 years (median, 3.17 years) to …

Prognostic Factors For Male Breast Cancer: Similarity To Female Counterparts, Edward Yu, Larry Stitt, Olga Vujovic, Kurian Joseph, Avi Assouline, Joseph Au, Jawaid Younus, Francisco Perera, Patricia Tai

Edward Yu

Abstract. Aim: To assess whether prognostic factors in male (MBC) and female (FBC) breast cancer have similar impact on survival. Patients and Methods: Charts for men and women diagnosed with breast cancer referred to the London Regional Cancer Program (LRCP) were reviewed. Patients with distant metastatic diseases were excluded. Data on prognostic factors including age, nodal status, resection margin, use of hormonal therapy, chemotherapy with/without hormone and radiation therapy (RT), overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS) were analyzed. Survival estimates were obtained using Kaplan-Meier methodology. The Cox regression interaction was used to compare male and female …

Three-Dimensional Segmentation Of Three-Dimensional Ultrasound Carotid Atherosclerosis Using Sparse Field Level Sets., E Ukwatta, J Yuan, D Buchanan, B Chiu, J Awad, W Qiu, G Parraga, A Fenster

Medical Biophysics Publications

PURPOSE: Three-dimensional ultrasound (3DUS) vessel wall volume (VWV) provides a 3D measurement of carotid artery wall remodeling and atherosclerotic plaque and is sensitive to temporal changes of carotid plaque burden. Unfortunately, although 3DUS VWV provides many advantages compared to measurements of arterial wall thickening or plaque alone, it is still not widely used in research or clinical practice because of the inordinate amount of time required to train observers and to generate 3DUS VWV measurements. In this regard, semiautomated methods for segmentation of the carotid media-adventitia boundary (MAB) and the lumen-intima boundary (LIB) would greatly improve the time to train …

Improving Cervical Cancer Nodal Boost Radiation Therapy By Quantifying Uncertainties And Exploring Advanced Radiation Therapy Modalities, Zhiqian Yu

Dissertations & Theses (Open Access)

Radiation therapy for patients with intact cervical cancer is frequently delivered using primary external beam radiation therapy (EBRT) followed by two fractions of intracavitary brachytherapy (ICBT). Although the tumor is the primary radiation target, controlling microscopic disease in the lymph nodes is just as critical to patient treatment outcome. In patients where gross lymphadenopathy is discovered, an extra EBRT boost course is delivered between the two ICBT fractions. Since the nodal boost is an addendum to primary EBRT and ICBT, the prescription and delivery must be performed considering previously delivered dose. This project aims to address the major issues of …

Improving Acute Stroke Management With Ct Perfusion Imaging: Approaches To Treatment Guidance And Brain Tissue Salvage, Christopher D. D'Esterre

Electronic Thesis and Dissertation Repository

CT Perfusion (CTP) provides measurement of perfusion at the capillary level which can be used to characterize tissue viability, and blood-brain-barrier (BBB) compromise. Using CTP, the goals of this research are to: 1) select patients that will benefit from acute stroke treatment, and 2) determine if pre-stroke neuroprotection reduces stroke severity.

Chapter two investigates the cerebral blood volume (CBV) parameter in a small acute ischemic stroke (AIS) patient set. Overestimation of the acute CBV defect is caused by incomplete wash-out of the CT contrast due to a shortened CTP acquisition time (“truncation artifact”).

In chapter three we examine the prognostic …

Flash4 Dark Reference Images, George Mcnamara

George McNamara

Hamamatsu FLASH4.0 dark reference images, acquired with 10 second exposure times, no light to camera. Camera offset (set by Hamamatsu( is ~100 (the average intensity of the first image is always ~1 intensity level higher - an odd feature, but trivial in practice for a 16-bit camera).

George McNamara, Ph.D.

Single Cells Analyst at L.J.N. Cooper Lab

University of Texas M.D. Anderson Cancer Center

On The Role Of Abnormal Dl(Co) In Ex-Smokers Without Airflow Limitation: Symptoms, Exercise Capacity And Hyperpolarised Helium-3 Mri, Miranda Kirby, Amir Owrangi, Sarah Svenningsen, Andrew Wheatley, Harvey O Coxson, Nigel A M Paterson, David G Mccormack, Grace Parraga

Medical Biophysics Publications

BACKGROUND: The functional effects of abnormal diffusing capacity for carbon monoxide (DLCO) in ex-smokers without chronic obstructive pulmonary disease (COPD) are not well understood.

OBJECTIVE: We aimed to evaluate and compare well established clinical, physiological and emerging imaging measurements in ex-smokers with normal spirometry and abnormal DLCO with a group of ex-smokers with normal spirometry and DLCO and ex-smokers with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I COPD.

METHODS: We enrolled 38 ex-smokers and 15 subjects with stage I COPD who underwent spirometry, plethysmography, St George's Respiratory Questionnaire (SGRQ), 6 min Walk Test (6MWT), x-ray CT and …

Delta Relaxation Enhanced Magnetic Resonance - Development And Application Of A Field-Cycling Contrast Mechanism, Yonathan Araya

Electronic Thesis and Dissertation Repository

Delta relaxation enhanced magnetic resonance (dreMR) is a novel imaging method capable of producing contrast proportional only to the concentration of the bound form of the targetable contrast agent using a dynamic field-cycling technique. The characteristic high relaxivity magnetic field dependence of bound paramagnetic contrast agents enables suppression of tissue contrast from unbound agents and unenhanced tissue, thereby increasing probe specificity. The dreMR technique requires an auxiliary actively shielded field-shifting insert electromagnet to modulate the strength of the main clinical magnetic field as a function of time during the relaxation and evolution periods of a pulse sequence.

Ablavar (approved for …

A Magnetic-Resonance-Imaging-Compatible Remote Catheter Navigation System., Mohammad Ali Tavallaei, Yogesh Thakur, Syed Haider, Maria Drangova

Medical Biophysics Publications

A remote catheter navigation system compatible with magnetic resonance imaging (MRI) has been developed to facilitate MRI-guided catheterization procedures. The interventionalist's conventional motions (axial motion and rotation) on an input catheter - acting as the master - are measured by a pair of optical encoders, and a custom embedded system relays the motions to a pair of ultrasonic motors. The ultrasonic motors drive the patient catheter (slave) within the MRI scanner, replicating the motion of the input catheter. The performance of the remote catheter navigation system was evaluated in terms of accuracy and delay of motion replication outside and within …

Magnetic Resonance Imaging Of Brain Tissue Abnormalities: Transverse Relaxation Time In Autism And Tourette Syndrome And Development Of A Novel Whole-Brain Myelin Mapping Technique, Yann Gagnon

Electronic Thesis and Dissertation Repository

The transverse relaxation time (T2) is a fundamental parameter of magnetic resonance imaging sensitive to tissue microstructure and water content, thus offering a non-invasive approach to evaluate abnormalities of brain tissue in-vivo. Prevailing hypotheses of two childhood psychiatric disorders were tested using quantitative T2 imaging and automated region of interest (ROI) analyses. In autism, the under-connectivity theory, which proposes aberrant connectivity within white matter (WM) was assessed, finding T2 to be eleveted in the frontal and parietal lobes, while dividing whole brain data into neurodevelopmentally relevant WM ROIs found increased T2 in bridging and radiate WM. In Tourette syndrome, tissue …

Chronic Obstructive Pulmonary Disease: More Imaging, More Phenotyping...Better Care?, Damien Pike, Grace Parraga

Medical Biophysics Publications

No abstract provided.

Video Codec Performance (Excel Spreadsheet), George Mcnamara

George McNamara

Video codec performance (Excel spreadsheet). Movie was made in 2005-2006 when I worked at City of Hope National Medical Center. VTLF refers to Video Timelapse Light Facility. Videos were outputted from MetaMorph as AVI files. Personally, I always recommend uncompressed video files fro scientific uses. I also encourage posting the original scientific data format (ex. .lsm, .zvi, .lif, .stk).

Pubspectra Tattletales, George Mcnamara

George McNamara

Tattletales for Multiplex Fluorescent Reporters in Single Cells for Metabolomics

George McNamara

As of April 2013: L.J.N. Cooper & D.A. Lee Cellular Immunotherapy Lab, University of Texas M.D. Anderson Cancer Center, Houston, TX

Email: gtmcnamara@mdanderson.org, geomcnamara@earthlink.net

Tattletales is my concept for spatial multiplexing many fluorescent protein (FP) biosensors in the same live cell. For example, there are excellent FP biosensors to Ca++ ions, pH, glucose, ribose, glutamine, glutamate, ATP, redox, ROS, pyruvate, cAMP, cGMP, IP3, PI(3,4,5)P3, cell cycle indicators (Fucci2), PKA, PKC, photsphatases, caspase(s) [1, 2]. However, these are typically used one biosensor per experiment, due in part to flooding …

Atlas-Based Attenuation Correction For Pet/Mri, John Christian Patrick

Electronic Thesis and Dissertation Repository

Attenuation correction (AC) in PET/MRI is difficult as there is no clear relationship between MR signal and 511 keV attenuation coefficients (μ). One strategy is to align a pre-defined atlas of μ to the PET/MRI for AC. However, atlas design may influence quantitative accuracy of AC. In this thesis we compare 3 atlas design strategies and evaluate their performance in an oncology patient population. The 3 strategies were: correction with BMI-dependent atlases; gender-dependent atlases, and a gender- and sex-independent atlas. Patients were imaged with FDG PET/CT and 3T MRI. The atlases were created and then used for PET AC of …

Investigating Adenosine’S Role In Controlling The Cerebral Metabolic Rate Of Oxygen Following Hypoxia-Ischemia, Mustafa Ridha

Electronic Thesis and Dissertation Repository

The cerebral metabolic rate of oxygen (CMRO2) has been shown to be an early indicator of hypoxia-ischemia (HI); however, the mechanisms controlling post-HI CMRO2 are not clear. One potential mechanism is the activation of the adenosine A1 receptor due to increased adenosine concentrations during the insult. The present study investigated if the specific adenosine A1 antagonist, DPCPX, would reduce the typical reduction in CMRO2 and electrical cortical activity following HI. Measurements of CMRO2 and electrical cortical activity were obtained on piglets by near-infrared spectroscopy (NIRS) and amplitude-integrated electroencephalography (aEEG), respectively. The post-HI measurements of CMRO2 and mean aEEG background voltage …

Rescuing Acetylcholinesterase From Nerve Agent Inhibition: Protein Dynamics Driven Drug Discovery, Aiyana M. Emigh, Brian Bennion

STAR Program Research Presentations

Severe morbidity and mortality consequences result from irreversible inhibition of human acetylcholinesterase by organophosphates (OPs). Oxime-based reactivators are currently the only available treatments but lack efficacy in the central nervous system (CNS) where the most damage occurs. Computational docking and molecular dynamics (MD) simulations reveal complex structural barriers that may reduce oxime efficacy. These results may guide future drug designs of more effective countermeasures.

Mechanistic Basis For Atrial And Ventricular Arrhythmias Caused By Kcnq1 Mutations, Daniel C. Bartos

Theses and Dissertations--Physiology

Cardiac arrhythmias are caused by a disruption of the normal initiation or propagation of electrical impulses in the heart. Hundreds of mutations in genes encoding ion channels or ion channel regulatory proteins are linked to congenital arrhythmia syndromes that increase the risk for sudden cardiac death. This dissertation focuses on how mutations in a gene (KCNQ1) that encodes a voltage-gated K⁺ ion channel (Kv7.1) can disrupt proper channel function and lead to abnormal repolarization of atrial and ventricular cardiomyocytes.

In the heart, Kv7.1 coassembles with a regulatory protein to conduct the slowly activating delayed rectifier K^{+ …}

Prophylactic Cranial Irradiation For Patients With Limited-Stage Small-Cell Lung Cancer With Response To Chemoradiation, Patricia Tai, Avi Assouline, Kurian Joseph, Larry Stitt, Edward Yu

Edward Yu

Background Previous clinical studies have generally reported that prophylactic cranial irradiation (PCI) was given to patients with a complete response (CR) to chemotherapy and chest radiotherapy in limited-stage small-cell lung cancer (SCLC). It is not clear if those with incomplete response (IR) would benefit from PCI. Patients and Methods The Saskatchewan experience from 1981 through 2007 was reviewed. Patients were treated with chest radiotherapy and chemotherapy with or without PCI (typical doses: 2500 cGy in 10 fractions over 2 weeks, 3000 cGy in 15 fractions over 3 weeks, or 3000 cGy in 10 fractions over 2 weeks). Results There were …