Previous intravenous oxygenators relied on 02 diffusion to treat Acute Respiratory Distress Syndrome. However, bubble oxygenators may increase 02 transfer. Polypropylene and polysulfone hollow fiber membranes were modified using vapor graft polymerization (VGP) and solution graft polymerization (SGP) to decrease the pore size and porosity and increase the hydrophilicity of the fibers so that as 02 flowed through the treated fibers submerged in water the bubbles formed from the treated fiber would be smaller than those from pure fibers. Both methods increased the surface hydrophilicity; however, SGP decreased the fibers' porosity and pore sizes the most. After optimized VGP, 48% of polypropylene fibers' bubbles were 25-50 pm in radius, compared with 12% from pure polypropylene fibers. After optimized SGP, 38% of polysulfone fibers' bubbles were 25-50 pm in radius, compared with 21% from pure polysulfone fibers. However, treated polypropylene fibers required a pressure of 60 psig 02 to form bubbles.

Currently, malfunctioning heart valves are replaced via highly invasive and costly open-heart procedures. A new alternative approach is a catheter deliverable or percutaneous heart valve. Current PHV prototypes utilize fixed animal tissue as valves. This research investigated the feasibility of an artificial PHV and the development of a delivery system. A left hea11 simulator and a tensile tester were used to characterize the hydrodynamics and mechanics of a novel artificial PHV. Test results showed equal or better in vitro hydrodynamic performance when compared to a St. Jude mechanical valve and an Edwards-Sapien PHV, with a mean pressure drop of <15 mmHg and a mean regurgitation of <5%. The PHV's exceeded requirements for fixation and radial force. The 24 F delivery system successfully delivered and deployed a PHV. The work described herein proves the feasibility of an artificial PHV and delivery system and justifies further investigation into its design and function.

In this study the focal effects of moderate traumatic brain injury (TBI) on cerebral blood flow (CBF) as reported by SPECT cerebral brain perfusion (CBP) imaging in an animal model were investigated by parallelized statistical techniques. Subjects were randomly assigned to either a control group or test group receiving fluid percussion injury directly to the left parietal lobe. Qualitative SPECT CBP accuracy was assessed against reference radioactive microsphere technique (RMT) regional CBF measurements by map reconstruction, registration and smoothing. Cerebral hypoperfusion in the test group was then identified at the voxel level using a statistical parametric mapping (SPM) model. Using SPM-SPECT CBP, a significant area of hypoperfusion (P <0.01) was found as a characteristic response to the TBI. Further study and correlation o f this characteristic lesion with long-term outcomes and auxiliary diagnostic modalities is critical to developing more effective emergency treatment guidelines and automated medical imaging processing techniques.

The current development of hybrid SPECT/CT and PET/CT systems allows not only accurate attenuation correction of images, but also provide an anatomical frame for the 3D spatial representation of the dose distribution. The main goal of this thesis project was to develop computational algorithms for calculation of the 3D dose distribution delivered by internal emitters based on the images and information provided by new hybrid SPECT/CT and PET/CT systems. Although many experimental problems exist in patient-specific dosimetry, current drawback is the lack of radionuclide voxel S values for the set of all possible combinations of cubical and non-cubical pixel edges and thickness used in SPECT and PET studies. This work presents an alternative and computationally efficient method for calculating voxel S values based on the Monte Carlo volume integration of tabulated dose point-kernels of beta emissions over a voxel-to-voxel geometry. The accuracy of the calculations was compared with those determined by direct Monte Carlo radiation transport simulation.

One innovative thought in biomolecular electronics is the exploitation of electron transfer proteins. Using nature's self assembly techniques, proteins can build highly organized edifices with retained functional activity, and they can serve as platforms for biosensors. In this research work, Yeast Cytochrome C (YCC) is immobilized with a help of a linker molecule, 3-Mercaptopropyltrimethoxysilane (3-MPTS) on a hydroxylated surface of a silicon substrate. Atomic Force Microscopy (AFM) is used for characterization. AFM data shows immobilization of one YCC molecule in between eight grids that are formed by the linker molecules. 3-MPTS monolayers are organized in grids that are 1.2 nm apart. Immobilization of 3-MPTS was optimized using a concentration of 5 mM in a completely dehydrated state for 30 minutes. The functionally active grids of YCC can now be incorporated with Cytochrome C oxidase on a Platinum electrode surface for transfer of electrons in development of biosensors, such as nitrate sensor, that are small in size, cheaper, and easier to manufacture than the top-down approach of fabrication of molecular biodevices

Myocardial cell transplantation can compensate for the loss of necrotic cardiomyocytes. The objective of this research study was to reformulate the hydrogel with concentrations of growth factors, such as Leukemia Inhibitory Factor (LIF), Hepatocyte Growth Factor (HGF), and Interleukin-6 (IL-6). A controlled delivery system of PEO-PPO-PEO was formulated for release of a single growth factor and of multiple growth factors. Cytotoxicity and proliferation assay for single growth factors starting with 4000 skeletal myoblasts yielded their highest proliferation at 4 days with HGF (25,500 cells) and LIF (42,000 cells), while IL-6 (115,000 cells) generated its highest proliferation at 5 days. Combination of LIF and IL-6 resulted in highest proliferation at day 2 (220,000 cells), HGF and LIF (108,000 cells), and HGF and IL-6 (80,000 cells) both at 5 days. Viability at 37°C was maintained during the five days at 98-99%. The formulation was successful in myotube formation while maintaining a high purity of myoblasts in culture. The new formulation induced controlled release of growth factors and skeletal myoblasts delivery under favorable conditions while increasing the proliferation of myoblasts.

Bacteria are key players in the processes that govern fate and transport of contaminants. Previous assessment showed that the Arthrobacter oxydans (A.oxydans) G968 strain has a lower ability to tolerate U(VI) toxicity in bicarbonate-free media compared to other isolate A.oxydans G975. The study experimentally investigated several parameters such as the potential of bicarbonate to accelerate U(VI) release from autunite mineral in the presence of a less U(VI) tolerant bacterial strain, in the conditions mimicking Hanford Site subsurface environments. Results showed that despite morphological differences between the two bacterial strains, A.oxydans G968 and G975, they are able to dissolute uranium at the same capacity. The effect of both bacterial strands on autunite dissolution reduces as the concentration of bicarbonate increases. AFM and viability studies showed that samples containing bicarbonate are able to acclimate and withstand uranium toxicity. This study provides a better understanding of the bacterial role in polyphosphate remediation technology and interactions between meta-autunite and microbes.

MRI magnets are constantly evolving with technologies for higher fields, improving sensitivity and increasing resolution. Major achievements in MRI magnet technology in recent years include the successful construction of a 21.1-T, 900-MHz magnet system built at the National High Magnetic Field Laboratory and the soon to be completed series connected hybrid system capable of reaching 36 T. However, contrast agents used in MRI today are mostly based on iron oxides and gadolinium, which both have limited high field properties. A full assessment of the high field properties of existing contrast agents as well as alternate paramagnetic options, such as dysprosium, is required to better utilize these compounds for biomedical applications.<br />This dissertation involves the evaluation of existing intracellular MRI contrast agents at high magnetic fields as well as the development of a novel bimodal contrast agent optimized for these high fields. The focus is on the performance of the agents with emphasis on cell labeling and tracking in biological systems.<br />This dissertation will provide background on contrast agents and their relaxation properties as well as the cell lines and animal models used. An assessment of commercially available iron oxide particles as intracellular contrast agents was performed utilizing a rat microglia cell line. Internalized iron particles were imaged in tissue mimicking phantom at two high magnetic fields and evaluated based on contrast generated with increasing iron dose or cell concentration. Results show that iron oxide has limited benefit at higher magnetic fields mainly due to saturation below 1 T. The labeling of human mesenchymal stem cells (hMSC) with the same super-paramagnetic iron oxide nanoparticles was performed to evaluate uptake, viability, proliferation and differentiation for in vivo implantation.<br />To improve upon commercial agents, a novel bimodal contrast agent based on dysprosium and quantum dots was fabricated and analyzed. These nanoparticles were developed using the quantum dot not only as a fluorescent agent, imparting bimodal imaging capabilities, but also as a platform for increasing the number of Dy3+ that can be conjugated and delivered on a single nanoparticle to increase relaxivity. These particles have at least comparable T2 contrast to existing iron oxide agents, and the potential for increased improvement with advent of fields above 21.1 T (Rosenberg et al. Magn. Reson. Med., 64 (3) 2010). / A Dissertation submitted to the Department of Chemical and Biomedical Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2011. / April 1, 2011. / Includes bibliographical references. / Samuel C. Grant, Professor Directing Dissertation; Cathy Levenson, University Representative; Teng Ma, Committee Member; Anant Paravastu, Committee Member; Geoffery Strouse, Committee Member.

Texture analysis of pet scans as a tool for image quality assessment

There are lots of dynamic process exist co-currently and spontaneously when the neurons in the brain are activated by the external stimulation, like cerebral blood flow (CBF) change, oxygen extraction change. The study of the dynamic relationship among these physiological variables, which describe the brain activity through different aspects, can help people understand the brain function when it gets excited and researchers can interpret the physiological meaning of these parameters better. The most common functional magnetic resonance imaging techniques are BOLD and ASL fMRI, in this research, the correlation between these two methods has been studied through a simultaneous data acquisition strategy. Assessing such correlation between BOLD fMRI measures and CBF offers a link of these two to the underlying of the spontaneous brain activities. In the study, an ASL pulse sequence PICORE has been used to perform the fMRI experiment on 7 health subjects. A rapid median nerve electrical stimulation paradigm has been used to detect the activation of the brain from seven normal health right-handed human subjects. Three ROIs (SMA, S1, M1) have been selected and the data were analyzed to investigate the correlation between CBF value and BOLD signal change during brain activities. We found the CBF value rises for 5 - 6 ml/min/100g for fixed ROI and 11 - 12 ml/min/100g for non-fixed ROI and the BOLD signal change was around 0.8% for both situations. Our results shows for a fixed size ROI of each individual subject, no significant difference has been found for CBF value difference and the BOLD signal change between different runs and neither did the ratio of these two parameters (p > 0.05). When studied the activation area size for each run, we found significant difference for both CBF value difference and BOLD signal change (p < < 0.05) but no significant difference for the ratio of those two (p > 0.05). The dynamic relationship between CBF value difference and BOLD contrast signal change has been shown to be stable for a fixed ROI study. The amount of neurons being activated (activation size) for these two approaches has a habituation and decreased between runs, but the relationship between them remains typically the same since the ratio has no significant difference.