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Biomedical Engineering and Bioengineering Commons

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Theses/Dissertations

The Texas Medical Center Library

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Articles 1 - 12 of 12

Full-Text Articles in Biomedical Engineering and Bioengineering

The Role Of Gene Expression Noise In Mammalian Cell Survival, Kevin Farquhar May 2019

The Role Of Gene Expression Noise In Mammalian Cell Survival, Kevin Farquhar

UT GSBS Dissertations and Theses (Open Access)

Drug resistance and metastasis remain obstacles to effective cancer treatment. A major challenge contributing to this problem is cellular heterogeneity. Even in the same environment, cells with identical genomes can display cell-to-cell differences in gene expression, also known as gene expression noise. Gene expression noise can vary in magnitude in a population or in fluctuation time scales, which is influenced by gene regulatory networks.

Currently, it is unclear how gene expression noise from gene regulatory networks contributes to drug survival outcomes in mammalian cells. An isogenic cell line with a noise-modulating genetic system tuned to the same mean is required ...


Voxel-Level Absorbed Dose Calculations With A Deterministic Grid-Based Boltzmann Solver For Nuclear Medicine And The Clinical Value Of Voxel-Level Calculations, Justin Mikell Dec 2015

Voxel-Level Absorbed Dose Calculations With A Deterministic Grid-Based Boltzmann Solver For Nuclear Medicine And The Clinical Value Of Voxel-Level Calculations, Justin Mikell

UT GSBS Dissertations and Theses (Open Access)

Voxel-level absorbed dose (VLAD) is rarely calculated for nuclear medicine (NM) procedures involving unsealed sources or 90Y microspheres (YM). The current standard of practice for absorbed dose calculations in NM utilizes MIRD S-values, which 1) assume a uniform distribution in organs, 2) do not use patient specific geometry, and 3) lack a tumor model. VLADs overcome these limitations. One reason VLADs are not routinely performed is the difficulty in obtaining accurate absorbed doses in a clinically acceptable time. The deterministic grid-based Boltzmann solver (GBBS) was recently applied to radiation oncology where it was reported as fast and accurate for both ...


Selection Methods For Genetically-Modified T Cells: In Support Of Translational Therapy, David Rushworth May 2015

Selection Methods For Genetically-Modified T Cells: In Support Of Translational Therapy, David Rushworth

UT GSBS Dissertations and Theses (Open Access)

T cells are blood cells which organize the immune system of the host. These cells are necessary for the host to respond appropriately to threats from foreign organisms and cancerous growth. However, in the case of certain infections and cancer, T cells are unable to respond appropriately to a threat and establish immunity. This leads to disease when the infection or cancer is not sufficiently eliminated. On the other hand, T cells can lack tolerance for healthy tissue and perceive healthy tissue as infected. The ensuing over-reactive immune response also leads to disease. A delicate balance must exist between immunity ...


Characterization Of Low Density Intracranial Lesions Using Dual-Energy Computed Tomography, Jessica L. Nute May 2015

Characterization Of Low Density Intracranial Lesions Using Dual-Energy Computed Tomography, Jessica L. Nute

UT GSBS Dissertations and Theses (Open Access)

Calcific and hemorrhagic foci of susceptibility are frequently encountered on routine brain MR studies. Both etiologies cause variations in local magnetic field strength, leading to dark regions on the MR images that cannot be classified. Single-energy CT (SECT) can be used to identify lesions with attenuation over 100 HU as calcific, however lesions with lower attenuation cannot be reliably identified. While calcific lesions are unlikely to cause harm, hemorrhagic lesions carry a risk of subsequent intracranial bleeding; as such, identification of hemorrhage is vital in preventing the inappropriate use of anticoagulant medications in patients with hemorrhagic lesions.

Given there currently ...


Development Of A Multi-Purpose Automated Synthesis Module For Production Of Novel Pet Radiopharmaceuticals, I Hong Shih May 2014

Development Of A Multi-Purpose Automated Synthesis Module For Production Of Novel Pet Radiopharmaceuticals, I Hong Shih

UT GSBS Dissertations and Theses (Open Access)

Among radiopharmaceuticals of positron emission tomography (PET), 18F-Fluorodeoxyglucose (18F-FDG) made from commercialized automated synthesis module is the most frequently used in tumor diagnoses. But the false positive findings, such as infectious tissues and post-operative surgical conditions, show strong uptake of 18F-FDG in PET scans which requires extra clinical procedures to confirm the results. Moreover, the false negative findings, such as low glycolytic activity tumors, reduce the accuracy of PET scans. Therefore, there will be new PET radiopharmaceuticals to redeem the defects of 18FDG-PET applications.

Current commercialized automated synthesis modules are suitable for clinical use, but researchers ...


Bioactivity And Cell-Mediated Targeting Of Multistage Nanoporous Silicon Particles, Jonathan O. Martinez May 2014

Bioactivity And Cell-Mediated Targeting Of Multistage Nanoporous Silicon Particles, Jonathan O. Martinez

UT GSBS Dissertations and Theses (Open Access)

Progress in drug delivery approaches have not adequately translated into clinical advances in the diagnosis or treatment of inflammatory disorders (e.g., cancer). This disconnect is rooted in the inefficient delivery of imaging and therapeutic agents to the inflamed site upon systemic delivery. A multitude of biological barriers pose insurmountable obstacles limiting the ability of the agent to effectively reach and accumulate at the target site. Nanoparticles (NP) surfaced as potential vectors to encapsulate and deliver biological agents. However, even after surface decoration, NP have failed to evade biological barriers (i.e., MPS) and to accumulate at the tumor site ...


Delayed Thrombus Resolution And Fibroproliferative Vascular Wound Healing From Deficiency Of Type Iii Collagen: A Paradoxical Mechanism For Tissue Fragility, Amy J. Reid May 2013

Delayed Thrombus Resolution And Fibroproliferative Vascular Wound Healing From Deficiency Of Type Iii Collagen: A Paradoxical Mechanism For Tissue Fragility, Amy J. Reid

UT GSBS Dissertations and Theses (Open Access)

Vascular Ehlers-Danlos syndrome is a heritable disease of connective tissue caused by mutations in COL3A1, conferring a tissue deficiency of type III collagen. Cutaneous wounds heal poorly in these patients, and they are susceptible to spontaneous and catastrophic rupture of expansible hollow organs like the gut, uterus, and medium-sized to large arteries, which leads to premature death. Although the predisposition for organ rupture is often attributed to inherent tissue fragility, investigation of arteries from a haploinsufficient Col3a1 mouse model (Col3a1+/-) demonstrates that mutant arteries withstand even supraphysiologic pressures comparably to wild-type vessels. We hypothesize that injury that elicits occlusive thrombi ...


Novel Phantoms And Post-Processing For Diffusion Spectrum Imaging, Vaibhav Juneja May 2012

Novel Phantoms And Post-Processing For Diffusion Spectrum Imaging, Vaibhav Juneja

UT GSBS Dissertations and Theses (Open Access)

High Angular Resolution Diffusion Imaging (HARDI) techniques, including Diffusion Spectrum Imaging (DSI), have been proposed to resolve crossing and other complex fiber architecture in the human brain white matter. In these methods, directional information of diffusion is inferred from the peaks in the orientation distribution function (ODF). Extensive studies using histology on macaque brain, cat cerebellum, rat hippocampus and optic tracts, and bovine tongue are qualitatively in agreement with the DSI-derived ODFs and tractography. However, there are only two studies in the literature which validated the DSI results using physical phantoms and both these studies were not performed on a ...


Targeted Multistage Delivery Of Nanoparticles To The Bone Marrow, Aman Mann Aug 2011

Targeted Multistage Delivery Of Nanoparticles To The Bone Marrow, Aman Mann

UT GSBS Dissertations and Theses (Open Access)

Bone marrow is a target organ site involved in multiple diseases including myeloproliferative disorders and hematologic malignancies and metastases from breast and prostate. Most of these diseases are characterized with poor quality of life, and the treatment options are only palliative due to lack of delivery mechanisms for systemically injected drugs which results in dose limitation to protect the healthy hematopoietic cells. Therefore, there is a critical need to develop effective therapeutic strategies that allow for selective delivery of therapeutic payload to the bone marrow. Nanotechnology-based drug delivery systems provide the opportunity to deliver drugs to the target tissue while ...


In-Vivo Ct Dosimetry During Virtual Colonoscopy, Jonathon W. Mueller Aug 2011

In-Vivo Ct Dosimetry During Virtual Colonoscopy, Jonathon W. Mueller

UT GSBS Dissertations and Theses (Open Access)

Virtual colonoscopy (VC) is a minimally invasive means for identifying colorectal polyps and colorectal lesions by insufflating a patient’s bowel, applying contrast agent via rectal catheter, and performing multi-detector computed tomography (MDCT) scans. The technique is recommended for colonic health screening by the American Cancer Society but not funded by the Centers for Medicare and Medicaid Services (CMS) partially because of potential risks from radiation exposure. To date, no in‐vivo organ dose measurements have been performed for MDCT scans; thus, the accuracy of any current dose estimates is currently unknown.

In this study, two TLDs were affixed to ...


New Tools For Monitoring Gamma Camera Uniformity, Brad K. Lofton Dec 2010

New Tools For Monitoring Gamma Camera Uniformity, Brad K. Lofton

UT GSBS Dissertations and Theses (Open Access)

Detector uniformity is a fundamental performance characteristic of all modern gamma camera systems, and ensuring a stable, uniform detector response is critical for maintaining clinical images that are free of artifact. For these reasons, the assessment of detector uniformity is one of the most common activities associated with a successful clinical quality assurance program in gamma camera imaging. The evaluation of this parameter, however, is often unclear because it is highly dependent upon acquisition conditions, reviewer expertise, and the application of somewhat arbitrary limits that do not characterize the spatial location of the non-uniformities. Furthermore, as the goal of any ...


Application Of Signal Advance Technology To Electrophysiology, Chris M. Hymel Aug 2010

Application Of Signal Advance Technology To Electrophysiology, Chris M. Hymel

UT GSBS Dissertations and Theses (Open Access)

Medical instrumentation used in diagnosis and treatment relies on the accurate detection and processing of various physiological events and signals. While signal detection technology has improved greatly in recent years, there remain inherent delays in signal detection/ processing. These delays may have significant negative clinical consequences during various pathophysiological events. Reducing or eliminating such delays would increase the ability to provide successful early intervention in certain disorders thereby increasing the efficacy of treatment.

In recent years, a physical phenomenon referred to as Negative Group Delay (NGD), demonstrated in simple electronic circuits, has been shown to temporally advance the detection of ...