Mutations in myosin may lead to severe muscle disorders that greatly reduce the quality of life. For example, the embryonic skeletal myosin (MYH3) mutation R672C leads to Freeman Sheldon Syndrome (FSS), a rare inherited disorder that causes severe contractures at birth. A comprehensive understanding of the relationship between protein structure and function is urgently needed to treat diseases such as FSS. Computational methods, such as molecular dynamics simulations, can be used to examine the effects of mutations on protein structure and function. However, the Protein Data Bank (PDB) is missing most human skeletal myosin heavy chain structures. We employed homology modelling to construct structures of human MYH3. To inform homology modeling, I generated a multiple sequence alignment of 7 human myosin genes. The extent of sequence identity was used to identify the optimum myosin isoforms to use as templates for model generation. For example, MYH3 and MYH7 were the most distinct at 78.93% similarity, which was expected as they are embryonic skeletal and adult cardiac myosin respectively. Specific sequence consensus at each position in the sequence was used to determine the most and least conserved regions of myosin. The cleft region was the most conserved; the N-terminal Domain was the least conserved. I used MYH7, adult cardiac myosin, as a template structure to derive a homology model of the ATP state of MYH3. A structure of MYH3 R672C was generated via in silico mutation of the wild type structure. Molecular dynamics of the resulting structures will be used to explore how R672C, which is located near myosin’s converter domain, alters myosin structure and function. This computational platform will model all phases of the cross-bridge cycle, potentially reveal new drug binding pockets, guide and be validated by in vitro experiments using human induced pluripotent stem cell derived myocytes (hiPSC-Ms).

The purpose of a newly developed foot prosthesis is to improve frontal plane foot adaptability for over 1 million adults living with lower extremity amputation in the US. On uneven ground, side slope, and turning corners, the anatomical foot can adapt but most prosthetic feet cannot. The innovative prosthesis mimics biomechanical aspects of anatomical joints that use ligaments in tension throughout the range of motion while the joint surface acts as a specialized load-bearing structure similar to that of a cross four-bar linkage. In the current prototype cam linkage, we found deviation between the instantaneous center of rotation (ICR) and the point of contact (POC) as it rotated through the frontal plane. The error in this distance could cause unexpected wear on the prosthesis. The goal of this project was to reduce the error caused by the difference in location of the ICR and POC during rotation and translation of the four-bar linkage. In a crossed four-bar linkage, the ICR is found at the intersection of the crossing links. To find the path of the ICR, we plotted a series of points by rotating the linkage about a fixed link in space. The continuous ICR path was estimated by smoothing the ICR points. The curved shape developed becomes the load-bearing surface of the linkage. To create the upper and the lower load-bearing surface, the upper and lower link must be fixed and the opposite rotated, respectively. Using the method described, we built linkage assemblies that showed an error of 0.96 mm per 20 degrees of rotation compared to 2.17 mm of error in the original prototype. The International Organization for Standardization (ISO) requires that foot prostheses undergo wear and fatigue testing. Reducing potential wear on the prosthesis is advantageous because engineers can design for optimal product durability for the foot.

The dystrophin protein protects cardiac and skeletal muscle from damage during contraction and relaxation. Mutations in dystrophin lead to Duchenne muscular dystrophy (DMD), an incurable X-linked recessive disease affecting 1 in 3500 boys. Previous work has shown that several cardiac symptoms of DMD can be traced to calcium handling defects. To that end, a preliminary drug screen by our lab identified several L-type Calcium Channel blockers (CCBs) that were able to provide a cardioprotective effect. To conclusively determine the effectiveness of these CCBs, a platform that can accurately replicate physiological cardiomyocytes and screen these CCBs at semi-high throughput is needed. A major limitation with current drug screening platforms is that they use cardiomyocytes equivalent to the fetal heart. This is due to the limitations in current differentiation protocols, which fail to induce further maturity. Because symptoms of most inherited cardiomyopathies are exhibited in mature cardiomyocytes, these platforms are unable to predict drug efficacy accurately. Additionally, microelectrode array (MEA) systems - a system for high throughput drug studies - require highly accurate cell plating to provide good quality results, which requires extensive and costly training. Here, we addressed these issues by developing a novel platform that uses ComboMat, a technique used to enhance cardiomyocyte maturity, and designing an assistive device to plate cardiomyocytes in MEA plates. We showed that our platform with ComboMat-treated cardiomyocytes can give a more physiologically relevant response compared to platforms that use untreated cardiomyocytes. A MEA-based drug study is currently being performed to validate the CCBs identified in the preliminary drug screen. We expect to successfully validate a subset of the CCBs analyzed and further test them in animal models. This project will culminate in creating a novel and cost-effective platform that offers superior prediction of drug efficacy for DMD and potentially other cardiomyopathies as well.

In the United States, 1.5 million individuals suffer a fracture due to bone disease each year. In addition, there are many unknown mechanisms behind how muscular disorders and mechanical load adversely affect bone development, such as in the disease distal arthrogryposis. Disease research in human cell models has greater translational potential compared to animal models but have faced challenges when constructing highly-specialized tissues such as bone. We propose a novel, three-dimensional bone tissue model as a platform for musculoskeletal disease modeling that allows for compressive loading. By seeding induced pluripotent stem cell (iPSC) derived osteoblasts and osteoclasts in a 3D, porous, hydroxyapatite-coated poly-L-lactide scaffold, we propose to generate a bone tissue model that replicates human tissue in a laboratory. By applying compression to the novel 3D bone tissue model, we expect to observe phenotypes of bone disorders and bone development under mechanical loading. We propose to induce osteoblast and osteoclasts lineage from mesenchymal progenitor cells and hematopoietic progenitor cells, respectively, and co-culture to identify optimal conditions for cell growth. Preliminary experiments have found success in culturing active osteoblasts from iPSC-derived mesenchymal progenitor cells. By screening for markers of cell proliferation, calcium deposition, bone resorption and secretion, the cultures can be assessed for their robustness. In parallel, a porous scaffold will be fabricated by dissolving poly-L-lactide in chloroform and molding over sodium chloride particles. Coating said scaffold in fibronectin and hydroxyapatite will improve cell adhesion and uptake bone secretion. Seeding osteoclast and osteoblasts cells in a porous scaffold will allow for improved cell diffusion and 3D growth, mimicking the human microenvironment. We expect that combining robust, osteogenic tissue culture on a bioactive scaffold that allows 3D bone growth with mechanical loading will reveal phenotypes of distal arthrogryposis. Thus, this method has significant applications in accelerating laboratory findings to clinical research.

Duchenne Muscular Dystrophy (DMD) is a severe muscle wasting disease caused by the deficiency of dystrophin protein affecting ~1 in 3500 boys. Exercise has been investigated as a potential therapy but has shown conflicting effects on dystrophic muscle. Animal models that have been studied but do not fully mimic the disease and cardiac phenotype. Here, we provide the first known evaluation of exercise in a new DMD mdx rat model that mimics skeletal muscle and cardiac pathology. Having an animal model that better reflects the DMD cardiac phenotype is crucial in establishing physical activity guidelines that minimize potential damage to the heart. In Aim I of this pilot study, DMD mdx rats (n=3) and sibling wildtypes (WT; n=3) were assigned to wheel or treadmill exercise training groups (high intensity or low intensity) or unexercised (sedentary) for 6-weeks. Throughout this 6-week period, I was responsible for executing the rat treadmill exercise training protocol at low-to-moderate intensity (5x/week), and monitored the rat wheel running activity. Physiological measurements were conducted pre- and post- training (wheel running, treadmill testing, grip testing, echocardiography, and hindlimb force testing). Compared to wheel running or unexercised rats, treadmill training produced the greatest gain in treadmill exercise endurance testing and in fatigue-resistance in in-vivo hindlimb force testing for DMD rats. However, the treadmill program was associated with severe cardiac effects in DMD mdx, indicated by significant fibrosis and inflammation and echocardiography (Myocardial Performance Index, % fractional shortening and ejection fraction), a finding which will be investigated in subsequent cohorts.

 In the United States, there are approximately 2.5 million people with spinal cord injuries (SCIs). Depending on the location and severity of the injury, SCIs can result in long-term motor and sensory impairment. A very promising technology in neurorehabilitation for people with SCIs is transcutaneous spinal cord stimulation (tSCS). tSCS is a novel, non-invasive technique that stimulates the spinal cord through the surface of the skin. Recent clinical studies have already shown that tSCS is effective in helping to rehabilitate people with SCIs. However, while the rehabilitation method is sound, the physiological effects of tSCS on muscle recruitment are not well understood. Therefore, we are investigating the modulation of the spinal networks after the intervention with tSCS. Six patients with cervical SCIs underwent physical training paired with tSCS. Before and after training, SCS was used to induce motor evoked potentials which were measured with electromyogram. Evoked responses were extracted and analyzed by comparing peak to peak amplitude. After training and tSCS, both motor function and motor evoked potential amplitude increased, providing evidence that tSCS improves rehabilitation outcomes by modifying spinal networks. This research could lead to innovations in neural engineering and rehabilitation medicine and could greatly improve the quality of life for many people with SCIs.

Prior research suggests disproportionate endorsement of pain among Black, Indigenous, and People of Color (BIPOC) compared to White people. Considering the high prevalence of pain in persons with MS, the present study examined potential racial-ethnic differences in pain interference among adults with MS, both before and after participation in one of two telehealth interventions aimed at improving pain, fatigue, and depressive symptoms. A national sample of adults with MS and chronic fatigue, chronic pain and/or moderate depressive symptoms (N=163) participated in a randomized controlled trial of self-management intervention focused on cognitive behavioral therapy (n=75) versus MS education (n=88), both delivered 1:1 via telephone. T-tests explored racial-ethnic differences in pain interference at baseline and posttreatment. Hierarchical multiple regression assessed race/ethnicity as a predictor of posttreatment pain interference controlling for baseline pain interference, and in subsequent blocks explored treatment condition, treatment satisfaction variables and baseline perceived social support as factors accounting for potential racial-ethnic differences and variance in pain interference. Independent sample t-tests revealed significant racial-ethnic differences in pain interference at baseline, t(159)=2.30, p=.023 and posttreatment, t(141)=2.91, p=.004. Specifically, participants who identified as (BIPOC) endorsed greater pain interference at baseline (M=4.66, SD=2.54) and posttreatment (M=4.31, SD=2.56) compared to non-Hispanic White participants (M=3.59, SD=2.32 and M=2.81, SD=2.11, respectively). Hierarchical regression analysis revealed a significant relationship between race and posttreatment pain interference, which became non-significant after controlling for baseline pain interference. Perceived social support emerged as significantly associated with posttreatment pain interference, after controlling for all variables. Ethnicity/race and perceived level of social support accounted for more variance in posttreatment pain interference than treatment type. Future investigations aimed at understanding why BIPOC report higher pain levels posttreatment are necessary to inform and adapt current treatments to address more relevant factors contributing to BIPOC’s experience of pain.

Current research and development of robotic arms aims to increase both functionality and versatility. In the agriculture industry autonomous harvesting machines have the potential to be cost effective tools that efficiently pick crops, and robotic arms are a key component of that process. The agricultural robotics market was valued at $7.4 billion in 2020. Robotic arms available are typically designed to pick up one specific object. The market lacks solutions that can harvest a wide variety of crops quickly and carefully. The goal of this research is to develop an adaptable and robust grasping mechanism to attach to robotic arms for harvesting crops from a prototype developed for prostheses. This design adapts in position in response to the object geometry to reduce pressure on the object and requires less time to position the arm. Reducing pressure is a key metric in this study because of the fragile nature of many crops. Utilization of this mechanism reduces articulation time because it can adapt to the shape of the object being grasped at any orientation. My work in the lab has been to develop testing methods to prove these theories, both in simulation and through printing my own prototypes and performing physical tests. Preliminary virtual models and prototype tests consist of repeated grasp tests on a standard set of different grasp test objects including plastic fruits, cleaning supplies, and children’s toys. The objects are grasped repeatedly with and without the linkage mechanism attached. Results show that the mechanisms are adaptable and provide more contact area with the grasped object, reducing point pressure and requiring less articulation of the robotic arm. Further testing will apply the mechanisms in an agriculture setting and include prototyping with different materials and improved design.

For most of society, the word ‘disability’ is equated to loss, tragedy, difficulty, and absence of ‘normality’. But for many people, the lived experience of disability does not match up to those negative expectations. The social model of disability states that a person’s disability is not inherent to the person’s body/mind, but rather created by an interaction between the body/mind and the physical and social environment in which they exist. For example, if a wheelchair user lives in a town that has inaccessible buildings and a lack of caretaker support, then they are disabled by the environment. However, if that same individual lives in a town where physical accessibility, social attitudes, and support needs are met to enable full participation, then are they really disabled? What environments may exist where being a wheelchair user is actually an advantage? The idea of ‘disability gain’ seeks contexts in which disabilities become advantageous to the individual, as opposed to detrimental. To explore this idea of ‘disability gain’, semi-structured interviews and focus groups were conducted with Deaf and/or disabled-identifying individuals to understand their perceptions of ‘disability gain’ and experiences of disability as advantageous. Document analysis was also conducted with cultural artifacts from disability communities. These qualitative data were analyzed using a content analysis framework until themes emerged. This study is ongoing, and results from this research are currently emerging and will be shared. This research provides a new perspective that shifts away from the ‘medical’ and ‘tragedy’ models, toward a more affirming,identity-positive model of disability.