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No description available.

No description available.

No description available.

Venous leg ulcers remain a problem in the United States, costing the health care industry nearly $1 billion annually. A major portion of this spending is incurred as a result of prolonged healing time. Compression therapy is known to promote recovery. This technique may be improved by allowing for dynamic customization of treatment parameters. The design of a sensing system for an intelligent compression stocking is described in this thesis. This sensing system will eventually serve as a means by which to quantify the performance of the stocking through the continuous measurement of key physiological variables. Blood flow velocity will be measured using an acoustic array, and leg volume will be quantified using bio-impedance techniques. Preliminary experiments were conducted in order to verify the responsiveness and practicality of using these technologies to monitor ulcer healing. The Edema Monitoring System was capable of resolving small changes in leg volume resulting from artificially-induced swelling. Unfortunately, the Acoustic Blood Flow Measurement System did not perform acceptably in terms of accuracy and robustness. Future directions for this technology include finding a more acceptable means by which to measure blood flow velocity, improving the sensing system by incorporating additional optimization parameters, exploring the use of alternative actuation mechanisms, and expanding its use to encompass all medical-grade compression stockings.

Engineered nanomaterials have structural features with at least one dimension in the 1?100 nm range. Because of their small size, nanoparticles possess unique chemical, mechanical, electrical, optical, magnetic, and biological properties that make them ideal candidates for a variety of novel commercial and medical applications. Particularly, carbon-based nanomaterials such as fullerenes, nanotubes, and nanowires are considered key elements in the development of new nano-applications with the potential to be used in everything from biomedicine and drug delivery systems to nanoelectronics and energy conservation mechanisms. Relatively unknown, however, is how exposure to nanoscale particles effects normal biological functions and processes. A major focus of recent toxicological research has begun to investigate the interactions between the biological environment and engineered nanoparticles and to determine appropriate safety standards that should be considered when interacting with nanomaterials. The purpose of this research is to investigate how fullerene-based amino acids interact with the biological environment both at the tissue and cellular levels and to identify factors, such as mechanical stimulation, that increase these interactions.

BACKGROUND: The development of a novel surgical tool or technique used in mitral valve repair can be hampered by the cost, complexity, and time associated with performing animal trials. We sought to develop a dynamically pressurized model which detects and quantifies mitral regurgitation in intact porcine hearts in order to preliminarily evaluate the effectiveness of mitral valve repair methods without the need for animal trials. METHODS: A computer controlled pulse duplication system was designed to accept freshly explanted porcine hearts and replicate a wide range of physiological conditions. To test the capabilities of this system in measuring mitral regurgitation, the cardiac output of four hearts was measured under two different peak left atrial pressures (120 and 150 mmHg) before and after induced mitral valve failures. Measurements were compared with clinically standard echocardiographic images. RESULTS: For all trials, cardiac output decreased as peak left atrial pressure was increased. After induction of mitral valve insufficiencies, cardiac output decreased, with a peak regurgitant fraction of 27%. These findings correlated well with the results from echocardiography. CONCLUSIONS: The resulting system is able to consistently and reliably detect and quantify mitral regurgitation and serves as an effective tool for the design of mitral valve repair techniques. The system is advantageous in its low experimental cost and time associated with each trial, while still allowing for surgical evaluations in an intact heart.

Computational modeling can be used to achieve a better understanding of fluid analysis within the pulmonary circulation. Boundary conditions are used in fluid analysis to determine the pressure and flow profiles of the blood as it moves through the lung. Accurate boundary conditions are critical in providing accurate models of blood pressure and blood flow. An important consideration when determining boundary conditions for the pulmonary vasculature is the effect of respiration on the impedance of the pulmonary vasculature. An additional consideration for the pulmonary vasculature is the physiologic differences between the pulmonary circulation and that of the systemic circulation. This research determines impedance boundary conditions for the pulmonary vasculature that reflect the specific geometry of the lung and correspond to maximal inspiration and maximal expiration. The analysis was performed using an existing one-dimensional finite element analysis system. The boundary conditions were defined by a bifurcating structure tree with a number of variables that were used to change the resistance of the pulmonary vessels. The variables within the structure tree were altered to reflect the differences between the pulmonary circulation and the systemic circulation. These variables include the length to radius ratio of the vessels in the structure tree and the asymmetry as the branches. A respiration factor was used to scale the vessels of the structure tree to reflect the effects of respiration on the geometry of the lung. The compliance of the vessels was also changed to reflect the more distensible vessels found in the pulmonary system. The geometry of the lung was defined with the structured tree parameters at maximal inspiration and the respiration factor was used to scale the defined geometry and reflect maximal expiration. The parameters were determined by utilizing an optimization technique. The Levinberg-Marquardt least-squares non-linear optimization algorithm was used to find a set of non-unique optimal parameters. The computed data was validated using measured pressure and flow data collected in a previous study.

The objective of this research is to develop a series of material treatments and modifications, and, using a standardized set of tests, determine the extent of the ability of the modified material to enhance coagulation. This research focuses on materials commonly used in traditional textile based wound dressings; utilizing Streaming Potential studies, Scanning Electron Microscopy (SEM) and Thrombin Assays. The materials tested can be classified into 4 groups: control materials, modified PLA, SAMs treated glass, and TEOS treated materials. The control materials included: spun cotton and rayon yarn; continuous filament Nylon, Polypropylene (PP), and Polyethylene terephthalate (PET); heat cleaned glass (control glass); and PLA staple fibers. Contact angle measurements showed that both the control glass and the PET showed an increase in contact angle when treated with TEOS. This corresponds to a decrease and no improvement, respectively, in thrombogenicity for these materials in the thrombin assay. The remaining materials tested showed no change or a decrease in contact angle after TEOS treatment, and a corresponding increase in thrombogenicity. These results support previous studies that indicate an increase in wettability contributes to the enhancement of coagulation (16). While the streaming potential studies showed no correlation between thrombin formation or contact angle data, these tests provided an important launching platform for future studies utilizing the Streaming Potential Jar. Future work could benefit from the use of more physiologically relevant solutions, such as CaCl2, NaCl, or other blood substitutes (15). While no definitive correlations between test methods were elucidated, the results garnered from this research created a strong launching platform from which future materials research can continue.

Osteoarthritis is a severely debilitating joint disorder. It is slowly progressing chronic disease and has no precise known causes. Impact injury can lead to cellular and matrix changes in articular cartilage similar to those seen in osteoarthritis. Impact injury models are often used as models for osteoarthritis. The purpose of this study was to use an in vitro impact injury model to examine the distribution and timing of apoptosis cell death following an impact injury. In this study it was hypothesized that there will be an increase in apoptosis cells with increasing impact load; that over time in culture the number of apoptotic cells will increase due to lingering effects from the impaction; and that apoptosis will be most severe directly below the impaction. Paired porcine knees were obtained fresh and patellae were removed using sterile techniques. Controlled mechanical impactions were made on 12 patellae at 25 mm/s, using MTS load frame, to pre selected force levels of 1000N (characterized as medium) and 12 patellae were subjected to 2000N (characterized as high). The twelve non-impacted patellae were used as controls. Following impaction, the impact patellae were placed in organ culture for 0, 3, 7, or 14 days and subsequent degenerative changes over time were assessed. Apoptotic cells were quantified using terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) technique. The stained cells were quantified as a percentage of the total number of cells. Changes in percentage of apoptotic cells was analyzed with experimental factors impact level, days in culture ( 0, 3, 7, 14), distance from center of impaction, and depth in tissue. There was a significant depth and time dependent increase in the percentage of apoptotic cells for high impactions. A significant increase in percentage of apoptotic cells was observed from high impactions after 14 days culture time and a significant increase in percentage of apoptotic cells, for 0 days culture time was observed from medium impactions. In conclusion magnitude of load has significant effect on chondrocyte apoptosis throughout the depth of the cartilage tissue, but depends on culture time.