Correct muscular activation of the body segments during an overhand throw is achieved when movement originates in the larger and more proximal legs and trunk and moves sequentially to the smaller, distal segments of the shoulder and arm. This sequence permits angular velocity to transfer progressively through the throw as part of an open kinetic chain. The athlete can summate angular velocity and segmental forces only if he is able to create a separation between the body segments during the movement pattern, and this separation is thus essential to effective segmental sequencing for activation of the trunk muscles to occur separately from distal segment motion. Limited mobility of the shoulder and scapula during the kinematic sequence will limit the ability of that segment to receive and contribute to the angular velocity of its proximal neighbors and to apply its own muscle torque to the throwing implement. This may result in compensatory motion of the proximal muscle groups to meet the demands placed on the body. To establish a link between compensatory activation of the trunk muscles and mobility in the rotator cuff and to apply this relationship to the pattern of the overhand throw, activity in the latissimus dorsi and external oblique/quadratus lumborum muscles was measured using surface electromyography in 40 college-age participants during arm flexion and lateral shoulder rotation. Muscle activation was recorded both before and after mobilization of relevant throwing muscles through targeted functional exercise. Results showed no significant change but suggested a general decrease in the level of peak muscle activation after participants engaged shoulder exercises. This is indicative of a downward trend in compensatory trunk activation during the initiation of shoulder motion. An increase in overall trunk muscle activity was also observed after exercise, which may imply a simultaneous engagement of the proximal throwing muscles in response to shoulder motion.

Tissue plasminogen activator (tPA) is most effective the faster it is able to be administered to a patient that has been affected by stroke. A Stroke Code is a strategy that acute care facilities implement to reduce the time from diagnosing a stroke to administering tPA. The purpose of this study was to determine if the initiation of a Stroke Code in an acute care hospital reduces the door-to-needle time for patients affected by a stroke. In particular, does a Stroke Code reduce door-to-needle times. The research was conducted using data from April 1, 2014 to December 31, 2014 (pre-Stroke Code period) and September 1, 2015 to December 31, 2016 (post-Stroke Code period). The population of this study was treated at Holston Valley Medical Center in Kingsport, Tennessee. The analysis revealed a decrease in door-to-needle times after a Stroke Code was implemented at the acute care facility.

Amyotrophic lateral sclerosis (ALS) is a lethal, progressive neurodegenerative disorder that selectively affects both upper and lower motor neurons, leading to muscle weakness, paralysis and death. Despite recent advances in the identification of genes associated with ALS, the quest for a sensitive biomarker for rapid and accurate diagnosis, prognosis, and treatment response monitoring has not been fulfilled. In this thesis, I report a method of quantifying the integrity of motor neurons in vivo using imaging to record uptake and retrograde transport of intramuscularly injected tetanus toxin fragment C (TTC) into spinal motor neurons. This method tracks and profiles progression of disease (transgenic SOD1G93A and PFN1 ALS mice) and detects subclinical perturbations in net transport, as analyzed in C9orf72 transgenic mice. It also defines a progressive reduction in net transport with aging. To address whether our technique enables drug development, I evaluated therapeutic benefits of (1) gene editing and (2) mutant gene silencing (with RNAi targeting SOD1) in SOD1G93A transgenic mice by characterizing their net axonal transport profiles. I constructed a computational model to evaluate key molecular processes affected in net axonal transport in ALS mouse model. The model allows prediction of key parameters affected in a C9ORF72 BAC transgenic mouse line. Prior immunization with tetanus toxoid does not preclude use of this assay, and it can be used repetitively in the same subject. This assay of net axonal transport offers broad clinical application as a diagnostic tool for motor neuron diseases and as a biomarker for rapid detection of benefit from therapies for transport dysfunction in a range of motor neuron diseases.

Stroke is the third most common cause of death and a leading cause of disability in the United States. The existing treatments of acute ischemic stroke (AIS) involve pharmaceutical thrombolytic therapy and/or mechanical thrombectomy. The Food and Drug Administration (FDA)-approved recombinant tissue plasminogen activator (tPA) administration for treatment of stroke is efficacious, but has a short treatment time window and is associated with a risk of symptomatic hemorrhage. Other than tPA, the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) retriever system and the Penumbra Aspiration system are both approved by the FDA for retrieval of thromboemboli in AIS patients. However, the previous clinical studies have shown that the recanalization rate of the MERCI system and the clinical outcome of the Penumbra system are not optimal. To identify the variables which could affect the performance of the thrombectomy devices, much effort has been devoted to evaluate thrombectomy devices in model systems, both in vivo and in vitro, of vascular occlusion. The goal of this study is to establish a physiologically realistic, in vitro model system for the preclinical assessment of mechanical thrombectomy devices. In this study, the model system of cerebrovascular occlusion was mainly composed of a human vascular replica, an embolus analogue (EA), and a simulated physiologic mock circulation system. The human vascular replica represents the geometry of the internal carotid artery (ICA)/middle cerebral artery (MCA) that is derived from image data in a population of patients. The features of the vasculature were characterized in terms of average curvature (AC), diameter, and length, and were used to determine the representative model. A batch manufacturing was developed to prepare the silicone replica. The EA is a much neglected component of model systems currently. To address this limitation, extensive mechanical characterization of commonly used EAs was performed. Importantly, the properties of the EAs were compared to specimens extracted from patients. In the preliminary tests of our model system, we selected a bovine EA with stiffness similar to the thrombi retrieved from the atherosclerotic plaques. This EA was used to create an occlusion in the aforesaid replica. The thrombectomy devices tested included the MERCI L5 Retriever, Penumbra system 054, Enterprise stent, and an ultrasound waveguide device. The primary efficacy endpoint was the amount of blood flow restored, and the primary safety endpoint was an analysis of clot fragments generated and their size distribution. A physiologically realistic model system of cerebrovascular occlusion was successfully built and applied for preclinical evaluation of thrombectomy devices. The recanalization rate of the thrombectomy device was related to the ability of the device to capture the EA during the removal of the device and the geometry of the cerebrovasculature. The risk of the embolic shower was influenced by the mechanical properties of the EA and the design of the thrombectomy device.

Magnetic resonance imaging (MRI) has emerged as the imaging modality of choice in a wide variety experimental and clinical applications. In this dissertation, I will describe novel MRI techniques for the characterization of neural and pulmonary vascular function in preclinical models of disease. In the first part of this dissertation, experimental results will be presented comparing the identification of ischemic lesions in experimental stroke using dynamic susceptibility contrast (DSC) and a well validated arterial spin labeling (ASL). We show that DSC measurements of an index of cerebral blood flow are sensitive to ischemia, treatment, and stroke subregions. Further, we derived a threshold of cerebral blood flow for ischemia as measured by DSC. Finally, we show that ischemic lesion volumes as defined by DSC are comparable to those defined by ASL. In the second part of this dissertation, a methodology of visualizing clots in experimental animal models of stroke is presented. Clots were rendered visible by MRI through the addition of a gadolinium based contrast agent during formation. Modified clots were used to induce an experimental embolic middle cerebral artery occlusion. Clots in the cerebral vasculature were visualized in vivousing MRI. Further, the efficacy of recombinant tissue plasminogen activator (r-tPA) and the combination of r-tPA and recombinant annexin-2 (rA2) was characterized by clot visualization during lysis. In the third part of this dissertation, we present results of the application of hyperpolarized helium (HP-He) in the characterization of new model of experimental pulmonary ischemia. The longitudinal relaxation time of HP-He is sensitive to the presence of paramagnetic oxygen. During ischemia, oxygen exchange from the airspaces of the lungs to the capillaries is hindered resulting in increased alveolar oxygen content which resulted in the shortening of the HP-He longitudinal relaxation time. Results of measurements of the HP-He relaxation time in both normal and ischemic animals are presented. In the final part of this dissertation, I will present results of a new method to measure pulmonary blood volume (PBV) using proton based MRI. A T1 weighted, inversion recovery spin echo sequence with cardiac and respiratory gating was developed to measure the changes in signal intensity of lung parenchyma before and after the injection of a long acting intravascular contrast agent. PBV is related to the signal change in the lung parenchyma and blood before and after contrast agent. We validate our method using a model of hypoxic pulmonary vasoconstriction in rats.

Lysophosphatidic acid (LPA) influences many physiological processes, such as brain and vascular development. It is associated with several diseases including ovarian cancer, breast cancer, prostate cancer, colorectal cancer, hepatocellular carcinoma, multiple myeloma atherosclerotic diseases, cardiovascular diseases, pulmonary inflammatory diseases and renal diseases. LPA plasma and serum levels have been reported to be important values in diagnosing ovarian cancer and other diseases. However, the extraction and quantification of LPA in plasma are very challenging because of the low physiological concentration and similar structures of LPA to other phospholipids. Many previous studies have not described the separation of LPA from other phospholipids, which may make analyses more challenging than necessary. We developed an SPE extraction method for plasma LPA that can extract LPA at high purity. We also developed an HPLC post-column fluorescence detection method that allows the efficient quantification of LPA. These methods were used in a clinical study for ovarian cancer diagnosis to help validate LPA as a biomarker of ovarian cancer. Moreover, molecular imprinted polymers (MIPs) were designed and synthesized as material for the improved extraction of LPA. Compared to the commercially available materials, the MIP developed shows enhanced selectivity for LPA. The extraction was overall relatively more efficient and less labor-intensive.

This project evaluates the ability of terahertz (THz) radiation to differentiate cancerous from non-cancerous human breast lumpectomy and mastectomy tissue. This is done by aiming a narrow-band THz beam at medical samples and measuring reflected power. THz images of specimens from Breast Conservation Surgery (BCS) were created using a gas laser source and mechanical scanning. The design and characterization of this system is discussed in detail. The images were correlated with optical histological micrographs of the same specimens and discrimination values of more than 70% were found for five of the six samples using Receiver Operating Characteristic (ROC) analysis.

The Alcohol Use Disorder Identification Test (AUDIT) is a brief screening instrument for assessing alcohol use problems among adults. This instrument is widely used and continued evaluation of its psychometric performance is needed. Reliability and validity are the primary psychometric characteristics of interest when evaluating psychological instruments. The focus of the present study is on reliability, which reflects the consistency or repeatability of the scores produced by a given instrument. Using meta-analytic methods, results showed that approximately 65% of previously published studies using the AUDIT did not appropriately report reliability estimates. Among the remaining studies, weighted reliability estimate centered on .81 (SD = .07) suggesting that the AUDIT generally produces scores of adequate reliability for most research purposes. Multiple regression equations showed that, among a variety of sample and methodological characteristics, the standard deviation of scores was the only statistically significant predictor of the variability in AUDIT score reliability estimates.

N,N′-methylenebisacrylamide-crosslinked poly(N-isopropylacrylamide), also known as P(NIPAM), was developed as a fluid delivery system for use with microfluidic paper-based analytical devices (microPADs). MicroPADs are postage-stamp-sized devices made out of paper that can be used as platforms for low-cost, simple-to-use point-of-care diagnostic assays. P(NIPAM) is a thermally responsive polymer that absorbs aqueous solutions at room temperature and will expel the solutions to microPADs when heated. The fluid delivery characteristics of P(NIPAM) were assessed, and P(NIPAM) was able to deliver multiple solutions to microPADs in specific sequences or simultaneously in a laminar-flow configuration. P(NIPAM) was then shown to be suitable for delivering four classes of reagents to microPADs: small molecules, enzymes, antibodies and DNA. P(NIPAM) successfully delivered a series of standard concentrations of glucose (0 – 5 mM) to microPADs equipped to perform a colorimetric glucose assay. The results of these tests were used to produce an external calibration curve, which in turn was used to determine accurately the concentrations of glucose in sample solutions. P(NIPAM) successfully delivered fluorescein-labeled IgG and fluorescein-labeled oligonucleotides (20 base pairs) to microPADs in a variety of concentrations. P(NIPAM) also successfully delivered horseradish peroxidase (HRP) to microPADs, and it was determined that HRP could be stored in P(NIPAM) for 35 days with minimal loss in activity. The combination of P(NIPAM) with microPADs will allow for more complex assays to be performed with minimal user input, will facilitate the preparation of external calibration curves in the field, and may be useful in extending the shelf life of microPADs by stabilizing reagents.

The condition of multimorbidity — the presence of two or more medical conditions in an individual — is a growing phenomenon worldwide. In the United States, multimorbid patients represent more than a third of the population and the trend is steadily increasing in an already aging population. There is thus a pressing need to understand the patterns in which multimorbidity occurs, and to better understand the nature of the care that is required to be provided to such patients. In this thesis, we use data from the Medical Expenditure Panel Survey (MEPS) from the years 2011 to 2015 to identify combinations of multiple chronic conditions (MCCs). We first quantify the significant heterogeneity observed in these combinations and how often they are observed across the five years. Next, using two criteria associated with each combination -- (a) the annual prevalence and (b) the annual median expenditure -- along with the concept of non-dominated Pareto fronts, we determine the degree of impact each combination has on the healthcare system. Our analysis reveals that combinations of four or more conditions are often mixtures of diseases that belong to different clinically meaningful groupings such as the metabolic disorders (diabetes, hypertension, hyperlipidemia); musculoskeletal conditions (osteoarthritis, spondylosis, back problems etc.); respiratory disorders (asthma, COPD etc.); heart conditions (atherosclerosis, myocardial infarction); and mental health conditions (anxiety disorders, depression etc.). Next, we use unsupervised learning techniques such as association rule mining and hierarchical clustering to visually explore the strength of the relationships/associations between different conditions and condition groupings. This interactive framework allows epidemiologists and clinicians (in particular primary care physicians) to have a systematic approach to understand the relationships between conditions and build a strategy with regards to screening, diagnosis and treatment over a longer term, especially for individuals at risk for more complications. The findings from this study aim to create a foundation for future work where a more holistic view of multimorbidity is possible.