Biomedical Engineering and Bioengineering Commons^™

Developing Afm Techniques For Testing Peg Hydrogels, Hannah L. Cebull, Jessica Stukel, Rebecca Willits

Williams Honors College, Honors Research Projects

Many instruments are used to find elastic properties of biological samples using methods such as tensile and bending tests, but using the atomic force microscope (AFM) is considered a non-destructive method because it can provide repeated local stiffness information without damaging the sample. It additionally allows the sample to be tested in an aqueous environment, which is optimal for soft materials such as hydrogels. The nanoindentation is performed via cantilever, measuring the deflection of the cantilever during the contact of the sample using a laser. Compared to hard samples, testing soft materials can present more challenges when working with the …

Development Of An Electrospun And 3d Printed Cellular Delivery Device For Dermal Wound Healing, Ryan M. Clohessy

Theses and Dissertations

The goal of this research was to develop a system of individualized medicine that could be applied to dermal wounds serving as a wound dressing and synthetic extracellular matrix while delivering stem cells to the wound bed. First, fabrication parameters for electrospinning polymer fibers were determined. This involved evaluating fiber morphology with respect to polymer selection and solution concentration. Next, construct fabrication was examined to produce an integrated void space, or cargo area, suitable to maintain stem cells. In vitro studies to ensure stem cell viability and phenotype were conducted, and results supported the notion that cells could be administered …

Identification Of Novel Ligands And Structural Requirements For Heterodimerization Of The Liver X Receptor Alpha, Shimpi Bedi

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LXRs, LXRa (NR1H3) and LXRß (NR1H2), are ligand-activated transcription factors that are members of the nuclear receptor superfamily. Oxysterols and nonsteroidal synthetic compounds bind directly to LXRs and influence the expression of LXR dependent genes. The use of murine models and LXR-selective agonists have established the important role of LXRs as sterol sensors that govern the absorption, transport, and catabolism of cholesterol. Upon activation, these receptors have been shown to increase reverse cholesterol transport from the macrophage back to the liver to aid in the removal of excess cholesterol. Not surprisingly, LXR dysregulation is a feature of several human diseases, …

A Novel System For Detection Of Dna Double Strand Breaks And Repair In Human Cells, Todd Warren Lewis

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Imperative to genomic stability is the ability of the cell to repair damaged DNA which can occur from numerous endogenous byproducts of metabolism or exogenous components from the environment. The Fanconi anemia pathway is a DNA repair mechanism used by human cells to resolve multiple forms of DNA damage including interstrand crosslinks (ICL). Fanconi anemia (FA) is an autosomal recessive inherited disorder characterized by genome instability, developmental abnormalities, cancer predisposition and bone marrow failure. FA is attributed to a mutations in at least 18 genes (FANCA-FANCT) that play a concerted role in DNA repair. FANCT is the latest discovery in …

Persistent Inward Currents Play A Role In Muscle Dysfunction Seen In Myotonia Congenita, Ahmed Alaa Hawash

Browse all Theses and Dissertations

Myotonia congenita is a rare skeletal muscle channelopathy caused by a reduced chloride channel (ClC-1) current, which results in debilitating muscle hyperexcitability, prolonged contractions, and transient episodes of weakness. The excitatory events that trigger myotonic action potentials in the absence of stabilizing ClC-1 current are not fully understood. My in vitro intracellular recordings from a mouse homozygous knockout of ClC-1 revealed a slow after-depolarization (AfD) that triggers myotonic action potentials. The AfD is well-explained by a tetrododoxin-sensitive and voltage-dependent Na+ persistent inward current (NaPIC). Notably, this NaPIC undergoes slow inactivation over seconds, thus providing the first mechanistic explanation for the …

Identifying The Impact Of Noise On Anomaly Detection Through Functional Near-Infrared Spectroscopy (Fnirs) And Eye-Tracking, Ryan Dwight Gabbard

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Occupational noise frequently occurs in the work environment in military intelligence, surveillance, and reconnaissance (ISR) operations. This impacts cognitive performance by acting as a stressor, potentially interfering with the analysts' decision making process. In this study the effects of different noise stimuli on analysts' performance and workload in anomaly detection were investigated by simulating a noisy work environment. Functional near infrared spectroscopy (fNIRS) was utilized to quantify oxy-hemoglobin (HbO) and deoxy-hemoglobin (HbD) concentration changes in the prefrontal cortex (PFC), as well as behavioral measures which include eye-tracking, reaction time, and accuracy rate. It was found that HbO for some of …

Functions Of The Apical Na+/ K+/ 2cl- Cotransporter 1 In Choroid Plexus Epithelial Cells, Jeannine Marie Crum Gregoriades

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Choroid plexus epithelial cells (CPECs) secrete cerebrospinal fluid (CSF) and regulate its electrolyte composition. CPECs express both the Na+/ K+ ATPase and the Na+/ K+/ 2Cl- cotransporter 1 (NKCC1) on their apical membrane (CSF facing), deviating from the typical basolateral membrane location in chloride secretory epithelia. Given this unusual location of NKCC1 and the unknown intracellular Na+ and Cl- concentrations of CPECs, the cotransporter function in these cells is not understood. Further, the direction of net ion and associated water fluxes mediated by NKCC1 under basal physiological conditions in CPECs is controversial. Determining the direction of NKCC1- mediated fluxes is …

Sensorimotor Deficits Following Oxaliplatin Chemotherapy, Jacob Adam Vincent

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Neurotoxicity is one of the most significant side effects diminishing clinical efficacy and patient quality of life during and following chemotherapy. Oxaliplatin (OX) is a platinum based chemotherapy agent used in the treatment of colorectal cancer. Colorectal cancer currently ranks as the 4th most common cancer, and the majority of patients receive OX as a part of their adjuvant therapy. OX based adjuvant therapies significantly improve 5 year survival rates, however in many cases patients must stop treatment early because of the neurotoxic side effects. OX causes two clinically distinct forms of neurotoxicity. Acutely, within hours and for days following …

Novel Mechanisms Underlying Warm-Up And Percussion Myotonia In Myotonia Congenita, Kevin Richard Nnovak

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Patients with myotonia congenita have muscle hyperexcitability due to loss-of-function mutations in the ClC-1 chloride channel in skeletal muscle, which causes spontaneous firing of muscle action potentials (myotonia), producing muscle stiffness. Triggers for myotonia can occur voluntarily at the neuromuscular junction or involuntarily by striking the muscle with a reflex hammer (percussion myotonia). In patients, muscle stiffness lessens with exercise, a change known as the warm-up phenomenon. Our goal was to identify the mechanism underlying warm-up and percussion myotonia and to use this information to guide development of novel therapies. To determine these underlying mechanisms, we used a drug to …

Persistent Inward Currents Play A Role In Muscle Dysfunction Seen In Myotonia Congenita, Ahmed Alaa Hawash

Browse all Theses and Dissertations

Myotonia congenita is a rare skeletal muscle channelopathy caused by a reduced chloride channel (ClC-1) current, which results in debilitating muscle hyperexcitability, prolonged contractions, and transient episodes of weakness. The excitatory events that trigger myotonic action potentials in the absence of stabilizing ClC-1 current are not fully understood. My in vitro intracellular recordings from a mouse homozygous knockout of ClC-1 revealed a slow after-depolarization (AfD) that triggers myotonic action potentials. The AfD is well-explained by a tetrododoxin-sensitive and voltage-dependent Na+ persistent inward current (NaPIC). Notably, this NaPIC undergoes slow inactivation over seconds, thus providing the first mechanistic explanation for the …

Functions Of The Apical Na+/ K+/ 2cl- Cotransporter 1 In Choroid Plexus Epithelial Cells., Jeannine Marie Crum Gregoriades

Browse all Theses and Dissertations

Choroid plexus epithelial cells (CPECs) secrete cerebrospinal fluid (CSF) and regulate its electrolyte composition. CPECs express both the Na⁺/ K⁺ ATPase and the Na⁺/ K⁺/ 2Cl^- cotransporter 1 (NKCC1) on their apical membrane (CSF facing), deviating from the typical basolateral membrane location in chloride secretory epithelia. Given this unusual location of NKCC1 and the unknown intracellular Na⁺ and Cl^- concentrations of CPECs, the cotransporter function in these cells is not understood. Further, the direction of net ion and associated water fluxes mediated by NKCC1 under basal physiological conditions in CPECs …

Computational Ultrasound Elastography: A Feasibility Study, Yu Wang

Dissertations, Master's Theses and Master's Reports

Ultrasound Elastography (UE) is an emerging set of imaging modalities used to assess the biomechanical properties of soft tissues. UE has been applied to numerous clinical applications. Particularly, results from clinical trials of UE in breast lesion differentiation and staging liver fibrosis indicated that there was a lack of confidence in UE measurements or image interpretation. Confidence on UE measurements interpretation is critically important for improving the clinical utility of UE. The primary objective of my thesis is to develop a computational simulation platform based on open-source software packages including Field II, VTK, FEBio and Tetgen. The proposed virtual simulation …

Surface Enabled Lab-On-A-Chip (Loc) Device For Protein Detection And Separation, Zhichao Wang

Dissertations, Master's Theses and Master's Reports

Sensitive and selective chemical/biological detection/analysis for proteins is essential for applications such as disease diagnosis, species phenotype identification, product quality control, and sample examination. Lab-on-a-chip (LOC) device provides advantages of fast analysis, reduced amount of sample requirements, and low cost, to magnificently facilitate protein detection research. Isoelectric focusing (IEF) is a strong and reliable electrophoretic technique capable of discerning proteins from complex mixtures based on the isoelectric point (pI) differences. It has experienced plenty of fruitful developments during previous decades which has given it the capability of performing with highly robust and reproducible analysis. This progress has made IEF devices …

Advancing Automated Methods For Microrna Profiling, Kia N. Zellars

Theses and Dissertations

The widespread influence of miRNAs in many biological processes and characteristic changes in expression profiles make them potential biomarkers for a range of diseases. With recent discoveries highlighting the enrichment of particular circulating miRNAs in plasma under pathological conditions, there has been a push for technological advances in miRNA profiling studies as a diagnostic tool. A standardized, automated, high-throughput method for miRNA isolation from human plasma samples was developed in this study. Samples were subject to full miRNome profiling utilizing RT-qPCR. These unique findings demonstrate that developing a distinct miRNA biomarker profile for heart failure patients is feasible and holds …

Statistical Shape Modeling To Quantify Variation In The Proximal Humeral Anatomy, Paul B. Sade Sr.

Electronic Theses and Dissertations

The fit of the humeral prosthesis to the intramedullary canal and the replication of the anatomic humeral head center are important factors in Total Shoulder Arthroplasty (TSA). The objective of this thesis was to develop a Statistical Shape Model (SSM) of the cortical and cancellous bone regions of the proximal humerus, and to assess potential shape differences with gender and ethnicity, with a goal of informing implant design. An SSM was used and Principal Component Analysis (PCA) was applied to data that represented both the cancellous and cortical humeral bone of 63 healthy subjects and cadavers. Anatomical measurements and PC …

Theoretically Proposed Optimal Frequency For Ultrasound Induced Cartilage Restoration, April D. Miller, Anuradha Subramanian, Hendrik J. Viljoen

Department of Chemical and Biomolecular Engineering: Faculty Publications

Background: Matching the frequency of the driving force to that of the system’s natural frequency of vibration results in greater amplitude response. Thus we hypothesize that applying ultrasound at the chondrocyte’s resonant frequency will result in greater deformation than applying similar ultrasound power at a frequency outside of the resonant bandwidth. Based on this resonant hypothesis, our group previously confirmed theoretically and experimentally that ultrasound stimulation of suspended chondrocytes at resonance (5 MHz) maximized gene expression of load inducible genes. However, this study was based on suspended chondrocytes. The resonant frequency of a chondrocyte does not only depend on the …

A Comprehensive Dosimetric Study On Switching From A Type-B To A Type-C Dose Algorithm For Modern Lung Sbrt, Christina Zhou, Nathan Bennion, Rongtao Ma, Xiaoying Liang, Shuo Wang, Kristina Zvolanek, Megan Hyun, Xiaobo Li, Sumin Zhou, Weining Zhen, Chi Lin, Andrew Wahl, Dandan Zheng

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Background: Type-C dose algorithms provide more accurate dosimetry for lung SBRT treatment planning. However, because current dosimetric protocols were developed based on conventional algorithms, its applicability for the new generation algorithms needs to be determined. Previous studies on this issue used small sample sizes and reached discordant conclusions. Our study assessed dose calculation of a Type-C algorithm with current dosimetric protocols in a large patient cohort, in order to demonstrate the dosimetric impacts and necessary treatment planning steps of switching from a Type-B to a Type-C dose algorithm for lung SBRT planning.

Methods: Fifty-two lung SBRT patients were included, each …

Phylogenomic Analysis Of Copepoda (Arthropoda, Crustacea) Reveals Unexpected Similarities With Earlier Proposed Morphological Phylogenies, Seong-Il Eyun

Nebraska Center for Biotechnology: Faculty and Staff Publications

Background: Copepods play a critical role in marine ecosystems but have been poorly investigated in phylogenetic studies. Morphological evidence supports the monophyly of copepods, whereas interordinal relationships continue to be debated. In particular, the phylogenetic position of the order Harpacticoida is still ambiguous and inconsistent among studies. Until now, a small number of molecular studies have been done using only a limited number or even partial genes and thus there is so far no consensus at the order-level.

Results: This study attempted to resolve phylogenetic relationships among and within four major copepod orders including Harpacticoida and the phylogenetic position of …

Evolutionary History Of Chemosensory-Related Gene Families Across The Arthropoda, Seong-Il Eyun, Ho Young Soh, Marijan Posavi, James B. Munro, Daniel S.T. Hughes, Shwetha C. Murali, Jiaxin Qu, Shannon Dugan, Sandra L. Lee, Hsu Chao, Huyen Dinh, Yi Han, Harshavardhan Doddapaneni, Kim C. Worley, Donna M. Muzny, Eun-Ok Park, Joana C. Silva, Richard A. Gibbs, Stephen Richards, Carol Eunmi Lee

Nebraska Center for Biotechnology: Faculty and Staff Publications

Chemosensory-related gene (CRG) families have been studied extensively in insects, but their evolutionary history across the Arthropoda had remained relatively unexplored. Here, we address current hypotheses and prior conclusions on CRG family evolution using a more comprehensive data set. In particular, odorant receptors were hypothesized to have proliferated during terrestrial colonization by insects (hexapods), but their association with other pancrustacean clades and with independent terrestrial colonizations in other arthropod subphyla have been unclear. We also examine hypotheses on which arthropod CRG family is most ancient. Thus, we reconstructed phylogenies of CRGs, including those from new arthropod genomes and transcriptomes, and …

A Method For Measuring The Attachment Strength Of The Cestode Hymenolepis Diminuta To The Rat Intestine, Wanchuan Xie, Gábor R. Rácz, Benjamin S. Terry, Scott Lyell Gardner

Scott L. Gardner Publications

A unique adaptation of many internal parasites of mammals is their ability to stay in the intestine for extended periods of time and resist the normal peristaltic movements and forces that push and expel material. To better understand parasite adhesion behavior and replicate their attachment method in medical devices, an experiment was designed and performed using the rat tapeworm, Hymenolepis diminuta. The experiment employed a tensile test machine and a digital scale and was designed to calculate the attachment strength of the scolex to the mucosa through the change of the value of the digital scale during the tensile …