Biomechanics and Biotransport Commons^™

Microgravity-Induced Alterations In Left Atrial Hemodynamics And Thrombogenic Risk: Insights From Healthy And Atrial Fibrillation Models, Grace M. Hoeppner

Dissertations, Master's Theses and Master's Reports

Background: Microgravity exposure alters cardiovascular loading, yet its impact on left atrial flow dynamics and thrombotic risk remains poorly understood. This study investigates how spaceflight-relevant microgravity-induced changes in cardiac outflow affect left atrial hemodynamics in healthy individuals and patients with atrial fibrillation.

Methods: Patient-specific left atrial models were generated for three healthy individuals and three AF patients. Computational fluid dynamics (CFD) simulations were performed using each patient’s baseline mitral outflow waveform and two modified waveforms representing short- and long-duration post-flight cardiac loading changes derived from echocardiographic observations. Hemodynamic metrics included left atrial velocity, time averaged wall shear stress, oscillatory shear …

Air-Jet Bioprinting Of Stem Cell-Encapsulated Alginate Micro-Droplets For Organoid Biomanufacturing, Mirabella B. Stump

Electronic Theses and Dissertations

Biomanufactured 3D-organoids show promise for modeling and treating various conditions, particularly insulin-dependent diabetes mellitus (type-1 diabetes). Pancreatic islet organoids serve as sustainable sources of insulin-producing β-cells, potentially restoring insulin regulation in patients and providing a long-term solution for diabetes. Hydrogel droplet printing is an emerging technique in regenerative medicine due to its advantageous tunability and biocompatibility; however, challenges of consistency, quality control, and scalability persist. To address these issues, we developed a novel air-jetting based droplet bioprinting system for the generation of monodispersed alginate micro-droplets. The objective of this project was to incorporate human induced pluripotent stem cells (hiPSCs) into …

Transport Barriers Influence The Activation Of Anti-Tumor Immunity: A Systems Biology Analysis, Mohammad R. Nikmaneshi, James W. Baish, Hengbo Zhou, Lance L. Munn

Faculty Journal Articles

Effective anti-cancer immune responses require activation of one or more naïve T cells. If the correct naïve T cell encounters its cognate antigen presented by an antigen presenting cell, then the T cell can activate and proliferate. Here, mathematical modeling is used to explore the possibility that immune activation in lymph nodes is a rate-limiting step in anti-cancer immunity and can affect response rates to immune checkpoint therapy. The model provides a mechanistic framework for optimizing cancer immunotherapy and developing testable solutions to unleash anti-tumor immune responses for more patients with cancer. The results show that antigen production rate and …

The Effects Of Demographics And Risk Factors On The Morphological Characteristics Of Human Femoropopliteal Arteries, Sayed Ahmadreza Razian, Majid Jadidi, Alexey Kamenskiy

UNO Student Research and Creative Activity Fair

Background: Disease of the lower extremity arteries (Peripheral Arterial Disease, PAD) is associated with high morbidity and mortality. During disease development, the arteries adapt by changing their diameter, wall thickness, and residual deformations, but the effects of demographics and risk factors on this process are not clear.

Methods: Superficial femoral arteries from 736 subjects (505 male, 231 female, 12 to 99 years old, average age 51±17.8 years) and the associated demographic and risk factor variables were used to construct machine learning (ML) regression models that predicted morphological characteristics (diameter, wall thickness, and longitudinal opening angle resulting from the …

Alternative Fixation Of Venous Valves For Bioprosthetic Applications, Makenzie Kapales

Biomedical Engineering Undergraduate Honors Theses

Venous valve failure allows for the retrograde, or backward, flow of blood into the lower extremities, which leads to Chronic Venous Insufficiency (CVI). CVI infringes upon quality of life through ulceration and can result in death due to Deep Vein Thrombosis (DVT), or blood clots, causing pulmonary embolism. A successful treatment of CVI restores valve function and prevents retrograde blood flow; however, current bioprosthetic venous valves exhibit low patency and high calcification. To improve upon bioprosthetic venous valves and CVI treatment, the University of Arkansas’s Cardiovascular Biomechanics Lab conducts studies with the purpose of comparing the properties and performance of …

Automatic Generation And Novel Validation Of Patient-Specific, Anatomically Inclusive Scoliosis Models For Biomechanics-Informed Surgical Planning, Austin Tapp, Michel Audette, James Bennett

College of Engineering & Technology (Batten) Posters

Scoliosis is an abnormal spinal curvature of greater than 10 degrees. Severe scoliotic deformities are addressed with highly invasive procedures: anterior or posterior spinal fusion approaches. This invasiveness is due, in part, to the constraints of current surgical planning, which utilizes computed tomography (CT) scans unable to discern spinal ligaments that are dissected to make the spine sufficiently compliant for correction. If localization of ligaments and soft tissues were achieved pre-operatively, corrective procedures could become safer and more efficient by using finite element (FE) biomechanical simulations to determine decreased incidences of ligament releases. This research aims to achieve ligament localization …

Development Of Light Actuated Chemical Delivery Platform On A 2-D Array Of Micropore Structure, Hojjat Rostami Azmand, Hojjat Rostami Azmand

Dissertations and Theses

Localized chemical delivery plays an essential role in the fundamental information transfers within biological systems. Thus, the ability to mimic the natural chemical signal modulation would provide significant contributions to understand the functional signaling pathway of biological cells and develop new prosthetic devices for neurological disorders. In this paper, we demonstrate a light-controlled hydrogel platform that can be used for localized chemical delivery in a high spatial resolution. By utilizing the photothermal behavior of graphene-hydrogel composites confined within micron-sized fluidic channels, patterned light illumination creates the parallel and independent actuation of chemical release in a group of fluidic ports. The …

Restoration Of Bone Material And Microstructural Properties After Long-Term Remodeling Suppression, Abigail A. Coffman

Dissertations and Theses

Anti-resorptive drugs, principally bisphosphonates (BPs), are the mainstay of osteoporosis treatment. They work by inhibiting bone resorption/remodeling, thus preventing bone loss. However, long-term suppression of bone resorption adversely affects bone tissue mechanical properties, even while conserving bone mass. Lack of remodeling leads to accumulation of fatigue-induced microdamage, altered matrix mineralization and reduction in normal bone tissue heterogeneity, causing impaired strength and fracture toughness. The most severe consequence to patients, while rare, is Atypical Femur Fractures (i.e., complete fatigue fractures of the femoral shaft). To counteract the effects of long-term remodeling suppression, a temporary break in BP treatment (a "drug holiday) …

Redesign And Quantitative Assessment Of An Accelerated Venous Valve Fatigue Apparatus, Megan Kueh

Biomedical Engineering Undergraduate Honors Theses

Chronic venous insufficiency (CVI) is a form of cardiovascular disease that is caused when valves in the leg become incompetent. Current treatment methods serve to manage symptoms, but there are currently no ways to treat the underlying cause of CVI. A venous valve prosthetic made from a xenograft of a bovine jugular vein is one possible treatment method currently in the research phase. Prosthetic valves must be tested with an accelerated wear tester prior to approval for clinical testing. Although such testers exist for heart valves, physiological differences between heart and venous valves restrict the use those testers on venous …

Characterization Of Bone Pathology In Sickle Cell Disease And Therapeutic Strategies, Mykel D. Green

Dissertations and Theses

Sickle cell disease (SCD) is a genetic hemoglobinopathy that has grown into a global health concern. While the advances in medical treatment and management of SCD during childhood have drastically improved the overall survival of children, the transition from pediatric to adult services is significantly inadequate in comparison. Life expectancies of patients with SCD in first world countries such as the United States are shortened to averages of 42 and 48 years for men and women, respectively. Despite the increasing number of people living with SCD, remarkably, few detailed studies have described the clinical course and complications of the disease …

The Impact Of Aging And Mechanical Injury On Alveolar Epithelial And Macrophage Responses In Acute Lung Injury And Inflammation, Michael S. Valentine

Theses and Dissertations

Patients with severe lung pathologies, such as Acute Respiratory Distress Syndrome (ARDS), often require mechanical ventilation as a clinical intervention; however, this procedure frequently exacerbates the original pulmonary issue and produces an exaggerated inflammatory response that potentially leads to sepsis, multisystem organ failure, and mortality. This acute lung injury (ALI) condition has been termed Ventilator-Induced Lung Injury (VILI). Alveolar overdistension, cyclic atelectasis, and biotrauma are the primary injury mechanisms in VILI that lead to the loss of alveolar barrier integrity and pulmonary inflammation. Stress and strains during mechanical ventilation are believed to initiate alveolar epithelial mechanotransduction signaling mechanisms that contribute …

Multidisciplinary Education And Research In Biomathematics For Solving Global Challenges, Padmanabhan Seshaiyer

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Gait Alterations In Peripheral Arterial Disease Are Not Worsened By The Presence Of Diabetes, Hafizur Rahman

UNO Student Research and Creative Activity Fair

Peripheral arterial disease (PAD) is a vascular disease where atherosclerotic blockages restrict blood flow to muscles in the lower extremities. Diabetes is a common co-morbid condition in PAD and has been shown to increase the risk of lower extremity amputation compared to PAD without diabetes. Although there is a clear pathological relationship between diabetes and PAD, the gait mechanics involved remain indistinct. Therefore, the purpose of this study was to determine whether the presence of diabetes in addition to PAD results in greater functional impairment during ambulation. Twenty-three subjects with PAD and twelve controls consented to participate in the research. …

Extraction And Analysis Of Vector Flow Imaging Data In A Pediatric Population, Bailey Stinnett

Biomedical Engineering Undergraduate Honors Theses

Vector flow imaging (VFI) is a new ultrasound technology that provides real time, angle-independent visualization of flow velocities in the heart and great vessels. Thus far, VFI has been used for superficial applications due to the limited penetration depth of available transducer probes; however, this depth in smaller pediatric patients enables adequate aortic views. In this project, VFI was used to study pediatric aortic stenosis (PAS)—a congenital heart defect that results in the narrowing of the aorta and/or aortic valve. The decision to refer PAS patients for surgical or catheter-based intervention is initially based on Doppler ultrasound. VFI is potentially …

The Effect Of Twist On The Mechanical Properties Of The Intervertebral Disc, Maxine Harvey-Burgess

Theses and Dissertations (Comprehensive)

Introduction: Intervertebral disc (IVD) herniation is a common injury to the IVD and a frequent source of low back pain. IVD herniation occurs when the nucleus pulposus migrates through both the inter- and intralamellar matrices of the annulus fibrosus (AF). There are a number of mechanical risk factors associated with herniation, including repetitive flexion and twist. In vivo, twist combined with repetitive flexion has been associated with increased experience of low back pain and herniation. Additionally, in vitro, when repetitive flexion is combined with twist, IVD herniation occurs more easily than repetitive flexion alone. However, the mechanisms behind …

Changes In Vessel Properties During Early Progression Of Murine Abdominal Aortic Aneurysms From In Vivo Ultrasound, Luis R. Avila Murati, Evan H. Phillips, Craig J. Goergen

The Summer Undergraduate Research Fellowship (SURF) Symposium

Abdominal aortic aneurysms (AAA) are a common and frequently fatal disease characterized by the weakening and dilation of the aorta. The larger the aneurysm, the higher the chances are of rupturing and life-threatening hemorrhage. The aim of this study is to apply the angiotensin II (AngII) model of AAAs in male apolipoprotein-E-deficient mice (apoE^-/- C57Bl/6J), in order to analyze, quantify, and understand the pathologies and characteristics associated with early AAA development. To date, many studies focusing on the evaluation of AAA characteristics have been performed ex vivo. Therefore, we focused on in vivo assessment, through the use of …