Biomedical Commons^™

A Knowledge-Based Clinical Toxicology Consultant For Diagnosing Multiple Exposures, Joel D. Schipper, Douglas D. Dankel Ii, A. Antonio Arroyo, Jay L. Schauben

Publications

Objective: This paper presents continued research toward the development of a knowledge-based system for the diagnosis of human toxic exposures. In particular, this research focuses on the challenging task of diagnosing exposures to multiple toxins. Although only 10% of toxic exposures in the United States involve multiple toxins, multiple exposures account for more than half of all toxin-related fatalities. Using simple medical mathematics, we seek to produce a practical decision support system capable of supplying useful information to aid in the diagnosis of complex cases involving multiple unknown substances.

Methods: The system is automatically trained using data mining …

Design And Fabrication Of Nanofluidic Systems With Integrated Sensing Electrodes For Rapid Biomolecule Characterization, Taylor Bradley Busch

Graduate Theses and Dissertations

A transparent nanofluidic system with embedded sensing electrodes was designed and fabricated by integrating Atomic Force Microscopy (AFM) nanolithography, Focused Ion Beam (FIB) milling and metal deposition, and standard microfabrication processing. The fabrication process started with the evaporation of chrome/gold (Cr/Au) onto a Pyrex 7740 wafer followed by photolithography and wet etching of the microchannels. The wafer was patterned a second time to form Au microelectrodes with 15-45 micrometer separation gaps in the nanochannel region. Sensing electrodes (up to one micron wide) were then deposited using FIB to bridge the gaps. The nanochannels were realized through both AFM nanolithography and …

The Geometry And Sensitivity Of Ion-Beam Sculpted Nanopores For Single Molecule Dna Analysis, Ryan Connor Rollings

Graduate Theses and Dissertations

In this dissertation, the relationship between the geometry of ion-beam sculpted solid-state nanopores and their ability to analyze single DNA molecules using resistive pulse sensing is investigated. To accomplish this, the three dimensional shape of the nanopore is determined using energy filtered and tomographic transmission electron microscopy. It is shown that this information enables the prediction of the ionic current passing through a voltage biased nanopore and improves the prediction of the magnitude of current drop signals when the nanopore interacts with single DNA molecules. The dimensional stability of nanopores in solution is monitored using this information and is improved …

Design And Testing Of Novel Mouthguard With Intermediate Nitinol And Foam Layers, Adam Kessler

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is the aim of this study to investigate a novel mouthguard design that incorporates the use of a nickel-titanium (Nitinol) layer and thin foam layer in addition to EVA layers. It is thought that the Nitinol layer can distribute the force of an impact and that the thin foam layer may absorb this distributed force better than a solid EVA mouthguard of the same thickness. Rectangular, flat coupons representative of several mouthguard configurations were constructed for testing using an instrumented drop-weight impact tower. The coupon configurations include a control made of laminated EVA, a group of laminated EVA and …

Closed Loop Control Of A Cylindrical Tube Type Ionic Polymer Metal Composite (Ipmc), Benjamin Mead

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this research is to provide a framework for the integration of tube type, cylindrical Ionic Polymer Metal-Composite (IPMC) into conventional devices. IPMCs are one of the most widely used types of electro-active polymer actuator, due to their low electric driving potential and large deformation range. For this research a tube type IPMC was investigated. This IPMC has a circular cross section with four separate electrodes on its surface and a hole through the middle. The four electrodes allow for biaxial bending and accurate control of the tip location. One of the main advantages of using this type …

Enhanced Diagnostic Accuracy Of Mammograms On A Mobile Device, Sharanya Padmanabhan

Open Access Theses

With the death of a woman every 13 minutes in the US, and one every minute worldwide, due to breast cancer, the need for early detection cannot be overstated. Mammography is a boon for both early detection and screening of breast tumors. It is an imaging system that uses low dose (9mrem) x-rays for examining the breasts, by the electrons reflected from the tissues (thermoelectric effect). However, there are 20% false positives and 10% false negatives in current practice. Hence, there is a critical need for enhancing the accuracy of these mammograms. Towards this, this thesis was aimed at enhancing …

Modeling Tools For Conformal Orthotic Devices, Steven David Riddle

Open Access Theses

The purpose of this thesis is to advance the design of conformal orthotic devices through the development of two modeling tools to address knowledge gaps in the field.

The field of human orthotics has been continually troubled by identifying successful methods of harnessing devices to the body. Past orthotics have utilized a rigid framework with minimal degrees of freedom (DOFs) driven by hard actuators attached to the body at select anchor points. Many devices design the structure and anchor points such that they reduce the degrees of freedom of a targeted joint, limiting the user's mobility and often causing the …

Using Multi-Processors To Reconstruct Images With Proton Computed Tomography, Chenwei Xu

Theses Digitization Project

This project will employ the use of multi-processor technology to reconstruct image data as fast as possible. Two-dimensional image reconstruction technique reconstructs images by solving a linear equation: A x x =b, where A is the path matrix of proton histories, b is electron matrix of the image, and x is the matrix of image. One row in matrix A represents one beam. Matrix A consists of a number of beam projections to the image, and each projection consists of a number of beams. Contains source code.

Detection Of Brain Abnormalities In Football Players Through Diffusion Weighted Imaging, Allan Emilio Diaz Gaez

Open Access Theses

Depression and cognitive impairment are commonly found in retired football players. Although they receive high magnitude hits to the head, the majority of the hits are sub-concussive, resulting in no clinical symptoms. Recent work using functional magnetic resonance (fMRI) and neurocognitive testing confirms that blows, causing changes in brain function, might not necessarily result in clinical diagnosis of concussion. Furthermore, cognitive deficiency in football players may be attributed to repetitive sub-concussive blows to the head. Diffusion weighted imaging (DWI) has previously been utilized to detect white matter (WM) abnormalities in mild traumatic brain injury (mTBI) patients, including those who have …

Sediment And Nutrient Behaviour On The River Bandon, Ireland, S. T. Harrington, Joseph R. Harrington

Conference Papers

This paper presents aspects of sediment and nutrient behaviour on the River Bandon which is located in the South Western River Basin District in Ireland; it is a relatively large sized river catchment in an Irish context with a catchment area of 608 km2. The river catchment is primarily agricultural with some pockets of urban development. The river is prone to flooding on stretches, features a number of special areas of conservation and is distinguished by both suspended and bed load transport. Continuous monitoring of turbidity commenced in February 2010. Manual sampling and testing for suspended sediment concentration and a …

Study Of The Effects Of Changing Physiological Conditions On Dielectric Properties Of Breast Tissues, Abas Sabouni, Camerin Hahn, Sima Noghanian, Edward Sauter, Tim Weiland

Electrical Engineering Faculty Publications

This paper addresses the changes in the physical characteristics (temperature and water/blood content) of breast tissue under different physiological conditions. We examined ex vivo specimens of breast tissue excised at the time of surgery to study the effects of physiological conditions on dielectric properties. We observed that the dielectric properties strongly depend on tissue physiological state. When the biological tissues undergo physiological changes, such as those due to disease or those induced by external changes such as variations in the environmental temperature, the microscopic processes deviate from their normal state and impact the overall dielectric properties. This suggests that microwave …

Recruitment Of The Intracellular Ca2+ By Ultrashort Electric Stimuli: The Impact Of Pulse Duration, Iurii Semenov, Shu Xiao, Olga N. Pakhomova, Andrei G. Pakhomov

Bioelectrics Publications

Nanosecond-duration electric stimuli are distinguished by the ability to permeabilize intracellular membranes and recruit Ca²⁺ from intracellular stores. We quantified this effect in non-excitable cells (CHO) using ratiometric Ca²⁺ imaging with Fura-2. In a Ca²⁺-free medium, 10-, 60-, and 300-ns stimuli evoked Ca2⁺ transients by mobilization of Ca²⁺ from the endoplasmic reticulum. With 2 mM external Ca²⁺, the transients included both extra- and intracellular components. The recruitment of intracellular Ca²⁺ increased as the stimulus duration decreased. At the threshold of 200–300 nM, the transients were amplified by calcium-induced calcium release. We …

Inkjet Based Personalized Screening Platform For Cancer Therapy, Jorge Ivan Rodriguez

Open Access Theses & Dissertations

The new paradigm of personalized medicine is beginning to affect clinical practice. In particular, many of the advances in genomics and proteomics have made personalized screening and therapeutic inventions possible. On chip, cellomics approaches to screening and intervention are becoming more commonplace. Cancer therapies may benefit from the rise in `-omics' technologies. In addition, the availability of rapid screening data is crucial to mitigate cancer propagation and increase the possibility of patient recovery. This study is an endeavor to develop a cellomic anticancer drug screening process based on inkjet printing. Previous research has demonstrated that inkjet based screening can reliably …

Effects Of Blood Flow On The Heating Of Cardiac Stents Due To Radio Frequency Fields, Nate Ian Elder

Open Access Theses

A safety concern during MRI scans with implanted medical devices is heating induced by the incident RF field. This research was performed to better understand the heating of cardiac stents during MRI. Heating of cardiac stents tends to occur at their ends. The temperature rise will be affected by blood flow through the lumen of the stent. In this work, an experiment was performed to simulate heating of a cardiac stent in the presence of blood flow during exposure to the electric field induced by a 64 MHz magnetic field, which corresponds to MRI at 1.5 T. The test procedure …

Vibrational Photoacoustic Tomography: Deep Tissue Imaging With Biomarker Sensitivity, Rui Li

Open Access Theses

As a molecular and functional imaging modality, photoacoustic imaging has been applied to animals or human organs such as breast, brain and skin. Till now, the contrast mechanism of photoacoustic imaging is mainly based on electronic absorption in visible and near infrared region. Inherent molecular vibration offers a contrast mechanism for chemical imaging in a label free manner. In vibrational microscopy based on either infrared absorption or Raman scattering, the imaging depth is limited to the ballistic photon mean free path, which is a few hundred microns in a biological sample. Owing to much weaker acoustic scattering in tissues as …

The Perceptual Salience Of Amplitude Modulated Cortical Stimulation: Peak Equivalence Or Rms Equivalence?, Oliver Brian Regele

Open Access Theses

Intracortical microstimulation (ICMS) is a method of electrically stimulating the primary motor, visual, somatosensory and auditory cortices in the brain. The goal is to replace deficient sensory function in cases such as deafness, blindness and paralysis. However these neural prosthetics have not made the full transition to clinical trials due to a lack of sufficient investigation into the optimal stimulation waveforms. Sinusoidally amplitude modulated (SAM) signals have been shown to be important to sensory systems, yet have not been fully explored as a stimulation waveform for stimulating cortical tissue.

This work represents an investigation into the detection characteristics of electrical …

Modulation Of Cell-Matrix Interaction For Cryopreservation Of Engineered Tissue, Angela Christine Seawright

Open Access Theses

Long term preservation of functional engineered tissues can significantly advance tissue engineering industry and regenerative medicine. Several preservation techniques have been proposed and investigated for this purpose, and cryopreservation is a leading candidate. While tissues are cryopreserved, ice forms in both the extracellular and intracellular spaces and causes freezing-induced spatiotemporal deformation of the tissue. During this process the cells undergo dehydration by the freezing-induced osmotic pressure difference and mechanical deformation, transmitted through cell-extracellular matrix adhesions. However, the significance and interaction of these cellular level transport and mechanics processes are not well understood. Therefore, this study aims to establish mechanistic understanding …

Role Of Microrna-155 In A Mouse Model Of Colon Cancer., Claire Mitchell Midyette

Theses and Dissertations

Colorectal cancer remains the third most common malignancy and the fourth most common cause of cancer mortality worldwide. Dysregulated miRNA levels are associated with several types of malignancies and may serve as important biomarkers and/or therapeutic targets in colorectal cancer. We examined the role of miRNA-155 on tumorigenesis and associated symptoms using a well-characterized mouse model of colorectal cancer. C57BL/6 wild-type mice and miRNA-155-/- mice (n=7-13 group) were given a single injection of AOM (10mg/Kg) followed by 3 cycles of DSS (2% in the water for 1 week followed by 2 weeks of plain water). A C57BL/6 wild-type group that …

Assessment And Evaluation Of The Dynamic Behavior Of Muscles With Special Reference To Subjects With Diabetes Mellitus, Jorge Garza-Ulloa

Open Access Theses & Dissertations

Diabetes mellitus (simply diabetes) is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced. Each year, the costs of diabetes rise. Diabetes and its complications cost our national economy. Two new methods are proposed to measure the diabetes implications in the muscles of lower body: Muscle energy expenditure analysis based on the detection of muscle transition-to-fatigue, and Natural Fuzzy logic method for differential analysis in muscle/joint. Then the results are compared with the traditional method …

Investigation Of Start Domain Proteins In Human Luteinized Cells And Cos-1 Cells, Bo Shi

Theses and Dissertations

After the luteinizing hormone surge of the menstrual cycle, the ovarian follicular granulosa and theca cells terminally differentiate to form the luteal cells of the corpus luteum. During this process known as luteinization, granulosa cells begin to synthesize large quantities of progesterone, a hormone essential for pregnancy. The rate limiting step for the de novo synthesis of pregnenolone (the precursor to progesterone) is the transport of cholesterol from the outer to the inner mitochondrial membrane, a process mediated by STARD1. STARD1 contains a C-terminal lipid binding domain holding one molecule of cholesterol, and an N-terminal domain targeting STARD1 to the …

Optimization Of Bioprinting Process Using Design Of Experiments (Doe) And Taguchi Method, Maria Veronica Gonzalez

Open Access Theses & Dissertations

At this time there is a need for new fabrication techniques for engineering complex biological structures related to regenerative medicine, in vitro tissue analysis, and pharmaceutical testing with the purpose of placing specific cells in specific target locations. Right now, there is no enough conventional cell seeding methods that can achieve it. In order to achieve it, bio-fabrication, which is a delivery mechanism capable of placing biomaterials, cells, and bioactive macromolecules in specific target locations, comes to play an important role in this area. Among different approaches, bioprinting is one of the most useful processes that use drop-on-demand delivery mechanisms …

Manufacturing Nerve Guidance Conduits By Stereolithography For Use In Peripheral Nerve Regeneration, Mireya Aidee Perez

Open Access Theses & Dissertations

Nerve regeneration techniques have been studied in great depth in recent years. Peripheral nerve injuries, in particular, can be caused by accidents, falls, athletic injuries, etc. Current methods of repair include direct suturing of the 2 injured nerve ends or the use of autografts, when a nerve section is taken from another area of the body. Both methods have a series of limitations which have led researchers to study alternative methods of repair. Nerve guidance conduits may provide a viable solution because they can be modified and adapted to the patient's needs. Some conduits already exist on the market and …

Printable Biodegradable Hydrogel For Skin Wound Dressing Using Inkjet Printing Technology, Maria G. Yanez

Open Access Theses & Dissertations

Chronic wounds are becoming more frequent. Foot ulcers affect approximately 10% - 15% of patients with diabetes throughout their lifetimes, and by 2025, it is estimated the prevalence of diabetes will be 250 million people in the worldwide. There is increased potential for patients with peripheral neuropathy and peripheral vascular disease to suffer more foot injuries. These conditions reduce the normal pain sensations and healing of minor traumas, allowing the development of chronic non-healing ulcers, often preceding lower-extremity amputation. These types of wounds are very difficult to treat and sometimes take months or even years to heal because of many …

Multi-Mode Self-Referencing Surface Plasmon Resonance Sensors, Jing Guo

Theses and Dissertations--Electrical and Computer Engineering

Surface-plasmon-resonance (SPR) sensors are widely used in biological, chemical, medical, and environmental sensing. This dissertation describes the design and development of dual-mode, self-referencing SPR sensors supporting two surface-plasmon modes (long- and short-range) which can differentiate surface binding interactions from bulk index changes at a single sensing location. Dual-mode SPR sensors have been optimized for surface limit of detection (LOD). In a wavelength interrogated optical setup, both surface plasmons are simultaneously excited at the same location and incident angle but at different wavelengths. To improve the sensor performance, a new approach to dual-mode SPR sensing is presented that offers improved differentiation …

Framework For Simulation Of Heterogeneous Mpsoc For Design Space Exploration, Bisrat Tafesse, Venkatesan Muthukumar

Electrical & Computer Engineering Faculty Research

Due to the ever-growing requirements in high performance data computation, multiprocessor systems have been proposed to solve the bottlenecks in uniprocessor systems. Developing efficient multiprocessor systems requires effective exploration of design choices like application scheduling, mapping, and architecture design. Also, fault tolerance in multiprocessors needs to be addressed. With the advent of nanometer-process technology for chip manufacturing, realization of multiprocessors on SoC (MpSoC) is an active field of research. Developing efficient low power, fault-tolerant task scheduling, and mapping techniques for MpSoCs require optimized algorithms that consider the various scenarios inherent in multiprocessor environments. Therefore there exists a need to develop …

Impact Of Physical Activity In The Prevention Of Colorectal Cancer, Sarah Ashley Barnes

Theses and Dissertations

This review evaluates the current understanding of research on the impact of physical activity in the prevention of colorectal cancer. Current biological mechanisms implicated in physical activity and colorectal cancer risk reduction are blood glucose regulation, insulin sensitivity, leptin and adiponectin profiles, inflammation as well as secreted protein acidic and rich in cysteine (SPARC), an exercise induced myokine. Recent literature indicates that 30-60 minutes of moderate to vigorous activity a day is effective against colorectal cancer development, and there is convincing evidence of aerobic exercise as differently beneficial in recruiting mechanisms identified as preventative against colorectal cancer. This article provides …

Resveratrol Attenuates The Development Of Trans-Aortic Constriction (Tac) Induced Heart Failure In Mice, Prakash Kumar Gupta

Theses and Dissertations

Heart failure (HF) still remains the leading cause of morbidity and mortality and imposes severe global affliction and enormous cost on the healthcare system. Although current pharmacological therapies have shown to slow down the progression of HF, but seems to have reached their limits in improving overall patient prognosis. Thus, an immediate call for novel alternate therapies are needed which act independently as well as in conjunction with current treatment modality. Studies were performed in the well-established transverse aortic constriction (TAC) model of chronic pressure overload (PO) in mice. In the first series of studies, Male C57BL6 mice (26-28 g) …

Linking Obesity To Colorectal Cancer: Recent Insights Into Plausible Biological Mechanisms, Catherine Guffey

Theses and Dissertations

Obesity has emerged as a leading environmental risk factor for the development of CRC. However, the mechanisms underlying this relationship have not yet been fully explained. Recent literature has focused on 1) inflammatory processes, 2) adipokines, and 3) estrogen. Obesity-enhanced inflammation is largely orchestrated by increases in adipose tissue macrophages leading to the secretion of TNF-alpha, MCP-1, and IL-6, all of which are linked to CRC. Adiponectin is decreased with obesity and has been reported to be negatively associated with CRC, while leptin, which is increased, is positively associated with the disease. Estrogen has been shown to influence CRC, although …

Microencapsulation Of A Connexin-43 Mimetic Peptide As A Novel Wound Healing Agent In An Ocular Injury Model, Keith Brian Moore

Theses and Dissertations

Corneal transplantation and related surgical procedures are areas of tissue replacement which have seen promising advances. Currently, cornea transplants are one of the most common surgical procedures, with approximately 40,000 occurring each year in the United States. Still, problems exist with a 20% rejection rate, post surgical infections, and the need for a constant supply of donors. The ability to safely and quickly heal and regenerate corneal epithelia fills an area of advancement in regenerative medicine, with implications reaching beyond the scope of vision therapies toward healing of a wide range of tissues and wounds. In vivo corneal wounds were …

Effect Of Physiological Oxygen Levels On Osteogenic Differentiation Of Adipose-Derived Stem Cells, Suchit Sahai

Theses and Dissertations

Regenerative medicine presents exciting strategies for healing critical-size bone defects through the implantation of cells and biocompatible scaffolds. Most in vitro studies are performed in atmospheric oxygen conditions (~20%), which do not accurately mimic the CSD microenvironment. Due to damage to the vasculature at CSDs, oxygen levels fall into the hypoxic range (<5%), which can impact viability, proliferation and differentiation of the cells employed for bone regeneration. Understanding the cellular responses to hypoxia has grown primarily from study of individual molecular factors. The master regulator of adaptive responses to low oxygen availability is the nuclear factor, hypoxia-inducible factor-1. HIF-1 is a heterodimeric protein, stable below 6% O2 condition in the nucleus and has been shown to play a role in angiogenic-osteogenic coupling. We have developed a responsive, fluorescent, hypoxia detection system and determined whether HIF activity can be tracked in both 2-D and 3-D cultures. Adipose-derived stem cells (ASCs) were selected due to their broad utilization in tissue engineering strategies and characterized the influence of HIF signaling on its phenotype. The work done identified that of hypoxia impaired osteogenic differentiation of ASCs in both 2-D and 3-D cultures and HIF-1 did not mediate this effect. Ischemic preconditioning (IPC) strategy and varied protocols used represents a clinically feasible manipulation of cell preparation to help the survival of implanted ASCs and accelerate osteogenic differentiation at physiological oxygen levels.