Matching Items (40)
Description
Aortic pathologies such as coarctation, dissection, and aneurysm represent a
particularly emergent class of cardiovascular diseases and account for significant cardiovascular morbidity and mortality worldwide. Computational simulations of aortic flows are growing increasingly important as tools for gaining understanding of these pathologies and for planning their surgical repair. In vitro experiments are required to validate these simulations against real world data, and a pulsatile flow pump system can provide physiologic flow conditions characteristic of the aorta.
This dissertation presents improved experimental techniques for in vitro aortic blood flow and the increasingly larger parts of the human cardiovascular system. Specifically, this work develops new flow management and measurement techniques for cardiovascular flow experiments with the aim to improve clinical evaluation and treatment planning of aortic diseases.
The hypothesis of this research is that transient flow driven by a step change in volume flux in a piston-based pulsatile flow pump system behaves differently from transient flow driven by a step change in pressure gradient, the development time being substantially reduced in the former. Due to this difference in behavior, the response to a piston-driven pump can be predicted in order to establish inlet velocity and flow waveforms at a downstream phantom model.
The main objectives of this dissertation were: 1) to design, construct, and validate a piston-based flow pump system for aortic flow experiments, 2) to characterize temporal and spatial development of start-up flows driven by a piston pump that produces a step change from zero flow to a constant volume flux in realistic (finite) tube geometries for physiologic Reynolds numbers, and 3) to develop a method to predict downstream velocity and flow waveforms at the inlet of an aortic phantom model and determine the input waveform needed to achieve the intended waveform at the test section. Application of these newly improved flow management tools and measurement techniques were then demonstrated through in vitro experiments in patient-specific coarctation of aorta flow phantom models manufactured in-house and compared to computational simulations to inform and execute future experiments and simulations.
particularly emergent class of cardiovascular diseases and account for significant cardiovascular morbidity and mortality worldwide. Computational simulations of aortic flows are growing increasingly important as tools for gaining understanding of these pathologies and for planning their surgical repair. In vitro experiments are required to validate these simulations against real world data, and a pulsatile flow pump system can provide physiologic flow conditions characteristic of the aorta.
This dissertation presents improved experimental techniques for in vitro aortic blood flow and the increasingly larger parts of the human cardiovascular system. Specifically, this work develops new flow management and measurement techniques for cardiovascular flow experiments with the aim to improve clinical evaluation and treatment planning of aortic diseases.
The hypothesis of this research is that transient flow driven by a step change in volume flux in a piston-based pulsatile flow pump system behaves differently from transient flow driven by a step change in pressure gradient, the development time being substantially reduced in the former. Due to this difference in behavior, the response to a piston-driven pump can be predicted in order to establish inlet velocity and flow waveforms at a downstream phantom model.
The main objectives of this dissertation were: 1) to design, construct, and validate a piston-based flow pump system for aortic flow experiments, 2) to characterize temporal and spatial development of start-up flows driven by a piston pump that produces a step change from zero flow to a constant volume flux in realistic (finite) tube geometries for physiologic Reynolds numbers, and 3) to develop a method to predict downstream velocity and flow waveforms at the inlet of an aortic phantom model and determine the input waveform needed to achieve the intended waveform at the test section. Application of these newly improved flow management tools and measurement techniques were then demonstrated through in vitro experiments in patient-specific coarctation of aorta flow phantom models manufactured in-house and compared to computational simulations to inform and execute future experiments and simulations.
ContributorsChaudhury, Rafeed Ahmed (Author) / Frakes, David (Thesis advisor) / Adrian, Ronald J (Thesis advisor) / Vernon, Brent (Committee member) / Pizziconi, Vincent (Committee member) / Caplan, Michael (Committee member) / Arizona State University (Publisher)
Created2015
Description
The aim of the present study was to review the symptoms and current treatment options of the most common skin infections seen in outpatient settings and develop a preliminary alternative treatment solution. The specific skin infections evaluated were those caused by Staphylococcus and Streptococcus bacterial species, and are frequently treated with a wide variety of systemic antibiotics or topical ointments. Systemic antibiotics have shown increased occurrence of adverse side effects as well as the development of antibiotic-resistant bacteria. Additionally, these medications are usually overprescribed, which may further exacerbate negative side effects. Another issue that is addressed is the development of infections following treatment of a new laceration or other trauma to the skin. A patient may be treated for their wound with stitches or another alternative, but there is still the possibility of developing an infection later.
This study synthesizes information found from extensive research and provides a review of the most optimal techniques for developing an alternative to systemic antibiotics. The final deliverable is a report detailing the significant findings and discussing the ways that this solution may be developed further and implemented in a clinical setting. The solution is a hydrogel bandage designed to deliver antibiotics directly to the wound site, while also offering protection and enhanced wound healing. The target population is patients suffering from skin conditions in an outpatient setting. The antibiotics of interest for this solution are clindamycin, doxycycline, and trimethoprim-sulfamethoxazole (co-trimoxazole), as they offer excellent treatment against gram-positive bacteria and methicillin-resistant Staphylococcus aureus. However, other broad-spectrum antibiotics could potentially be incorporated to protect against gram-negative bacteria. The design features a polyvinyl alcohol (PVA) hydrogel that has shown many properties that are beneficial to biomedical applications, including biocompatibility, flexibility, high drug-loading capacity, high absorption of wound exudate, increased promotion of wound healing, and more. Preliminary mathematical models of the hydrogel’s drug delivery behaviors are also included. Due to the scope and timeframe of this project, the majority of findings herein are based on research of prior literature instead of development of the novel device. Future directions would include further research and development of the mechanisms behind the device, creation of a physical prototype, experimental testing, and statistical analyses to verify device specifications and capabilities.
This study synthesizes information found from extensive research and provides a review of the most optimal techniques for developing an alternative to systemic antibiotics. The final deliverable is a report detailing the significant findings and discussing the ways that this solution may be developed further and implemented in a clinical setting. The solution is a hydrogel bandage designed to deliver antibiotics directly to the wound site, while also offering protection and enhanced wound healing. The target population is patients suffering from skin conditions in an outpatient setting. The antibiotics of interest for this solution are clindamycin, doxycycline, and trimethoprim-sulfamethoxazole (co-trimoxazole), as they offer excellent treatment against gram-positive bacteria and methicillin-resistant Staphylococcus aureus. However, other broad-spectrum antibiotics could potentially be incorporated to protect against gram-negative bacteria. The design features a polyvinyl alcohol (PVA) hydrogel that has shown many properties that are beneficial to biomedical applications, including biocompatibility, flexibility, high drug-loading capacity, high absorption of wound exudate, increased promotion of wound healing, and more. Preliminary mathematical models of the hydrogel’s drug delivery behaviors are also included. Due to the scope and timeframe of this project, the majority of findings herein are based on research of prior literature instead of development of the novel device. Future directions would include further research and development of the mechanisms behind the device, creation of a physical prototype, experimental testing, and statistical analyses to verify device specifications and capabilities.
ContributorsTanner, Emily Christine (Author) / Pizziconi, Vincent (Thesis director) / Nguyen, Eric (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This thesis aims to incorporate exosomes into an electrospun scaffold for tissue engineering applications. The motivation for this work is to develop an implant to regenerate tissue for patients with laryngeal defects. It was determined that it is feasible to incorporate exosomes into an electrospun scaffold. This addition of exosomes does alter the scaffold properties, by decreasing the average fiber diameter by roughly a factor of three and increasing the average modulus by roughly a factor of two. Cells were cultured on a scaffold with exosomes incorporated and were found to proliferate more than on a scaffold alone. This research lays the groundwork for further developing and optimizing an electrospun scaffold with exosomes incorporated to elicit a tissue regenerative response.
ContributorsKennedy, Maeve (Author) / Pizziconi, Vincent (Thesis director) / McPhail, Michael (Committee member) / School of International Letters and Cultures (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The adaptive artificial-intelligence (AI) medical device industry is a novel industry in the United States offering innovations to the healthcare field. The rapid expansion of this industry in recent years has drawn attention from multiple stakeholders causing a heated debate about how to introduce these innovations into the market while maintaining patient safety and treatment efficacy. Since early 2019, the U.S. Food and Drug Administration (FDA) has been releasing statements in regards to the improvement of regulation for this new technology, but has yet to take further actions. Dilemmas including 1) a difficult regulatory process, 2) a heightening financial burden and 3) looming liability issues, are reasons adaptive AI medical devices have struggled to be advanced. By conducting a thorough analysis of these 3 issues, recognizing the intricacies of them separately and together, this study develops a better understanding of the landscape adaptive AI technology is facing and provides a clearer picture for the future of the industry.
ContributorsOgden, Ravyn Nicole (Author) / Coursen, Jerry (Thesis director) / Pizziconi, Vincent (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Tissue engineering scaffold fabrication methods often have tradeoffs associated with them that prevent one method from fulfilling all design requirements of a desired scaffold. This undergraduate thesis seeks to combine 3D printing and electrospinning tissue engineering fabrication methods into a hybrid fabrication method that can potentially fulfill more design requirements than each method alone. The hybrid scaffolds were made by inserting electrospun scaffolds between layers of 3D printed scaffolds of increasing print temperature and effects on adhesion and mechanical properties were characterized. The fabrication method proved to be feasible and print temperature affected both adhesion and mechanical properties of the scaffolds. A positive, non-linear relationship was seen between print temperature and adhesion and resulting force. Insertion of electrospun mats led to increased damping of scaffolds. Evidence from characterization indicated factors other than print temperature were likely contributing to adhesion and mechanical properties. If studied further, this fabrication method could potentially be used to improve overall structure and regenerative potential of tissue engineering scaffolds.
ContributorsCornella, Joseph Paul (Author) / Pizziconi, Vincent (Thesis director) / McPhail, Michael J (Committee member) / School of Music (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Homeopathy is a brand of alternative medicine that has enjoyed a unique form of regulation for many years. This work aims to understand the regulation of homeopathic drugs in the United States by performing a literature review focused on three fronts: (i) homeopathy (theory, history in the United States and criticisms), (ii) U.S Food and Drug Administration (history and relationship to homeopathy), and (iii) interpretation of the law through reading guidance documents and the Code of Federal Regulations.
In 2015, the FDA began a process to reevaluate and update the regulations surrounding homeopathic products to better fit their present risk-based model. Past regulations were set in 1938; and as the world evolved, these have been found to set inadequate standards. By reviewing the agency’s guidance drafts and core regulatory documents, we come to understand that these changes are motivated by a desire for homeopathic remedies to follow high standards that apply to other products for the benefit of the U.S. consumers. FDA has made significant advances by proposing new Guidances on homeopathic products, listening to homeopathic community and consumers, and withdrawing the Compliance Policy Guide 400.400 issued in 1988.
We recommend for homeopathic manufacturers and practitioners to see the FDA as an ally and cooperate fully with the proposed changes for the regulation the agency gives out. Doing so will give the homeopathic community the best chance at continuing to sell their products and reach their consumers in the United States. In the same token, the FDA should do their best to involve homeopathic professionals in some way in this regulatory process, to encourage participation and compliance by the broader homeopathic community. Doing so ensures a climate of teamwork among different facets of the medical community in the United States.
In 2015, the FDA began a process to reevaluate and update the regulations surrounding homeopathic products to better fit their present risk-based model. Past regulations were set in 1938; and as the world evolved, these have been found to set inadequate standards. By reviewing the agency’s guidance drafts and core regulatory documents, we come to understand that these changes are motivated by a desire for homeopathic remedies to follow high standards that apply to other products for the benefit of the U.S. consumers. FDA has made significant advances by proposing new Guidances on homeopathic products, listening to homeopathic community and consumers, and withdrawing the Compliance Policy Guide 400.400 issued in 1988.
We recommend for homeopathic manufacturers and practitioners to see the FDA as an ally and cooperate fully with the proposed changes for the regulation the agency gives out. Doing so will give the homeopathic community the best chance at continuing to sell their products and reach their consumers in the United States. In the same token, the FDA should do their best to involve homeopathic professionals in some way in this regulatory process, to encourage participation and compliance by the broader homeopathic community. Doing so ensures a climate of teamwork among different facets of the medical community in the United States.
ContributorsRobayo, Juan Pablo (Author) / Pizziconi, Vincent (Thesis director) / Feigal, David (Committee member) / Frow, Emma (Committee member) / School of International Letters and Cultures (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Protein crystallization is a technique for the formation of three-dimensional protein crystals, which is widely utilized by scientists, engineers, and researchers. Protein crystallography allows for protein structures and functions to be studied. As proteins play a central role in biological systems and life itself, a deeper understanding of their structure-function properties is crucial to elucidating fundamental behaviors, such as protein folding in addition to the role that they play in emerging fields, such as, tissue engineering with application to the emerging field of regenerative medicine. However, a significant limitation toward achieving further advancements in this field is that in order to determine detailed structure of proteins from protein crystals, high-quality and larger size protein crystals are needed. Because it is difficult to produce adequate size, high-quality crystals, it remains difficult to determine the structure of many proteins. However, a new method using a microgravity environment to crystallize proteins has proven effective through various studies conducted on the International Space Station (ISS). In the presence of microgravity, free convection is essentially absent in the bulk solution where crystallization occurs, thus allowing for purely random Brownian motion to exist which favors the nucleation and growth of high-quality protein crystals. Many studies from the ISS to date have demonstrated that growing protein crystals in a microgravity environment produces larger and higher-quality crystals. This method provides new opportunities for better structure identification and analysis of proteins. Although there remains many more limitations and challenges in the field, microgravity protein crystallization holds many opportunities for the future of biotechnology and scientific development. The objective of this thesis was to study the crystallization of hen egg white lysozyme (HEWL) and determine the effects of both unit and microgravity on growth/size and quality of HEWL. Through preliminary trials using a universal ground-based reduced-gravity system, the crystallization of HEWL in a simulated microgravity environment was successfully conducted and the results reported are promising. The utility of continuous, scalable ground-based, microgravity platforms for studies on a wide range of material systems and behavior, such as, protein crystallization, has significant implications regarding its impact on many industries, including drug development as well as regenerative medicine.
ContributorsTran, Amanda Marie (Author) / Pizziconi, Vincent (Thesis director) / Alford, Terry (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
Regenerative medicine utilizes living cells as therapeutics to replace or repair damaged or diseased tissue, but the manufacturing processes to produce cell-based tissue products require customized biounit operations that do not currently exist as conventional biochemical and biopharma manufacturing processes. Living cells are constantly changing and reacting to their environment, which in the case of cells isolated from their hosts, are utilized as living bioreactor components that, by themselves, are manipulated to biomanufacturer selected tissue products. Therefore, specialized technology is required to assure that cellular products produce the phenotypical tissue characteristics that the final product is designated to have, while also maintaining sterility of the culture. Because of this, FDA guidelines encourage the use of Process Analytical Technology (PAT – see Ref ) to be integrated into manufacturing systems of biologics to ensure quality and safety. To address the need for evaluation of sensor technologies for potential use in PAT, a literature review of both existing sensing technologies and biomarkers was conducted. After a thorough assessment of the sensor technologies that were most applicable to biomanufacturing, spectrophotometry was selected to monitor the metabolic components glucose and lactate of living cells in culture in real time. Initially, spectrophotometric measurements were taken of mock solutions of glucose and lactate solutions at concentrations relevant to human cell culture and physiology. With that data, a mathematical model was developed to predict a solution’s glucose and lactate concentration. This model was then integrated into a Matlab program that was used to continuously monitor and estimate solutions of glucose and lactate concentrations in real time. After testing the accuracy of this program in different solutions, it was determined that calibration curves and models must be made for each media type and estimates of glucose and lactate were found accurate only at higher concentrations. This program was successfully utilized to monitor in real time glucose and lactate production and consumption trends of Mesenchymal Stem Cells (MSCs) in culture, demonstrating proof-of-concept of the proposed bioprocess monitoring schema.
ContributorsBerger, Aubrey (Author) / Pizziconi, Vincent (Thesis director) / Wang, Xiao (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2022-05
Description
Statistical process control (SPC) and predictive analytics have been used in industrial manufacturing and design, but up until now have not been applied to threshold data of vital sign monitoring in remote care settings. In this study of 20 elders with COPD and/or CHF, extended months of peak flow monitoring (FEV1) using telemedicine are examined to determine when an earlier or later clinical intervention may have been advised. This study demonstrated that SPC may bring less than a 2.0% increase in clinician workload while providing more robust statistically-derived thresholds than clinician-derived thresholds. Using a random K-fold model, FEV1 output was predictably validated to .80 Generalized R-square, demonstrating the adequate learning of a threshold classifier. Disease severity also impacted the model. Forecasting future FEV1 data points is possible with a complex ARIMA (45, 0, 49), but variation and sources of error require tight control. Validation was above average and encouraging for clinician acceptance. These statistical algorithms provide for the patient's own data to drive reduction in variability and, potentially increase clinician efficiency, improve patient outcome, and cost burden to the health care ecosystem.
ContributorsFralick, Celeste (Author) / Muthuswamy, Jitendran (Thesis advisor) / O'Shea, Terrance (Thesis advisor) / LaBelle, Jeffrey (Committee member) / Pizziconi, Vincent (Committee member) / Shea, Kimberly (Committee member) / Arizona State University (Publisher)
Created2013
Description
This honors thesis explores using machine learning technology to assist a patient's return to activity following a significant injury, specifically an anterior cruciate ligament (ACL) tear. The goal of the project was to determine if a machine learning model trained with ACL reconstruction (ACLR) applicable injury data would be able to correctly predict which phase of return to sport a patient would be classified in when introduced to a new data set.
ContributorsBernstein, Daniel (Author) / Pizziconi, Vincent (Thesis director) / Glattke, Kaycee (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2023-05