Current state-of-the-art upper limb prostheses have severely limited function. While there has been significant progress made in the last five years, allowing for the control of prostheses with thoughts, these methods do not yet allow for intuitive reaching movements. At the Rehabilitation Institute of Chicago (RIC), researchers have developed a method called "targeted muscle reinnervation" used to take the nerves left in the amputated limb and reroute them into intact muscle that is no longer useful (Kuiken et al, 2009). For instance, a person who has lost an arm at the shoulder would have the residual arm nerves at the shoulder rerouted to his chest muscle. As a result, when the person thinks about moving his phantom limb, his chest contracts. By using EMG to measure the amount of muscle activity in the chest, it is possible to use pattern recognition algorithms to map chest contractions to prosthetic arm movements. However, the current algorithms only allow for control over one action at a time. For example, a person cannot flex his elbow and rotate his wrist at the same time. This type of control can be likened to operating a crane, where only a single movement can be performed at a time. Consequently, movements such as reaching to a point in the workspace can become difficult and cumbersome.
A recent study (Loeb et al, 2008) by the University of Southern California shows that there is a strong correlation between the position/orientation of the forearm and the orientation of the shoulder measured with motion capture. This suggests that reaching could be implemented on a prosthesis for a person with an above-elbow amputation: by measuring the orientation of the shoulder, the corresponding position and orientation of the prosthesis could be estimated. Furthermore, we hypothesize that by including EMG to measure general muscle activity in the arm in addition to shoulder orientation, we can significantly increase the accuracy of the estimate. Our research proposes to develop and implement, both in simulation and clinically, various computational models of reaching in order to improve the function of upper limb prostheses. The results could greatly improve the quality of life for people with upper limb amputations.
The older population in today's society is growing rapidly and living longer. Despite the longer life span, one accepted aspect of normal development is a progressive change and deterioration in the ability to learn, perform cognitive tasks, and maintain memory. The extant literature suggests that aerobic exercise is an important and effective intervention to reduce and prevent cognitive decline associated with normal aging along with a multitude of other benefits associated with cardiovascular health. We are currently extending this body of research by investigating the effects of aerobic fitness training on human cognition and brain function of older adults.
A paper detailing my work was recently published: Palacios, D.S.; Anderson, T.M.; Burke, M.D. J. Am. Chem. Soc. 2007, Articles ASAP.
My research focuses on the structure/function relationships that underlie the biophysical properties of the antifungal drug amphotericin B. This clinically vital antimycotic has been in use for over 40 years for the treatment of life-threatening fungal infections despite its dose-limiting toxcitiy. The leading model for the antifungal activity of amphotericin B is self assembly of the natural product into a membrane-spanning ion channel that results in fungal cell death. While selective for fungal cells, this same mechanism is proposed to underlie amphotericin B toxicity. Two functional groups are predicted to stabilize the amphotericin B channel assembly: a carboxylate and an ammonium group are proposed to participate in a series of intermolecular salt bridges.
Using organic synthesis, we have prepared amphotericin B derivatives which lack either one or both of these two functional groups. Those derivatives lacking the ammonium group are inactive against s. cerevisiae and c. albicans yeast strains. Surprisingly, and in direct contradiction to the proposed channel model, the derivive lacking the carboxyl group retains full antifungal activity!
To unambiguosly intepret these observations, we employed nuclear magnetic resonance (NMR) to study the solution conformation of amphotericin B and our derivatives. Phase-sensitive COSY and NOESY NMR data were used to generate constraints for Monte Carlo conformational searches. Our results indicate that functional group deletion does not change the solution conformation of amphotericin B.
Taken together, these results indicate that the carboxylic acid oxidation state is not required for amphotericin B antifungal activity. At least two possibilities emerge: oxidation is not required for channel formation, and/or channel formation is not required for antifungal activity. Ongoing biophysical studies seek to differentiate these possibilities.
Future work will also focus on structure of the aphotericin B channel assembly. Solution and solid-state NMR will be employed to study intermolecular interactions between amphotericin B, membrane phospholipids, and membrane sterols. Ultimately, our goal is to unambiguosuly determine the stoichiometry and structure of the amphotericin-based ion channel.
Estrogens, acting via estrogen receptor (ER), stimulate the proliferation and metastatic potential of breast cancer. Tamoxifen, an anti-estrogen (AE), inhibits the oncogenic effects of ER by outcompeting estrogen for interaction with ligand-binding pocket of the receptor. Tamoxifen has been invaluable to advancing treatment, but remains ineffective against select tumor subpopulations, and can lead to drug resistance tumors with long-term administration. We aim to identify small molecules that bypass conventional molecular targets, inhibit an essential action of ER, and offer an avenue to clinically useful drugs to treat tumors resistant to conventional AEs. We also aim to further characterize (target identification/validation, mechanism of action) and optimize these compounds.
My research focuses on utilizing computational methods to understand and describe the membrane binding and activation of various proteins involved in hemostasis.
My research examines how veterans of the wars in Iraq and Afghanistan negotiate and enact newly-acquired disabled subjectivities within the socio-political contexts generated by both new government institutions of care and programming serving soldiers and veterans with disabilities, as well as the proliferation of discourse(s) on the war, disability, and disability rights. Post Traumatic Stress Disorder and Traumatic Brain Injury have figured prominently within national imagination of the effects of these wars on both soldiers and society. The formation of a new institutional care setting, the Polytrauma Center within the Veterans' Administration Health Care system, is a response to both improvements in care for individuals with traumatic injuries, as well as the resulting complexity of disabilities resulting from the warfare practices characterizing the Iraqi and Afghani conflict environments
The disabilities acquired by the soldiers of these wars constitute a range in the visibility of disablement. This range in visible states of disablement might be predicted to elicit a second continuum of responses from service providers, kin networks, and society at large within different domains of the soldier's life. My work seeks to characterize the interaction between the soldier with disability and other actors in his or her life with the aims of: A) defining the life experiences of a soldier with a disability that influence quality of life indices for these soldiers returning from war with acquired disabilities; and b) describing how soldiers with both "visible" and "invisible" disabilities such as spinal cord injuries and TBI respectively, negotiate the transition from a life valuing independence and physical and/or mental prowess to one of disablement, interdependency, and new systems of support.
With the large population of soldiers returning with acquired disabilities, as well as the formation of new institutions of care, there is a growing need to understand how ideological and discursive practices associated with new institutional formations and diagnostic categories form and are informed by the physical bodies and everyday experiences of soldiers and veterans with disabilities. I suggest that the processes of how disabled individuals' bodies, experiences, and subjectivities are made meaningful within different sociopolitical domains bear relevance to understanding everyday manifestations of health, citizenship, and disability rights.
Applications of martingale techniques to target tracking and analysis of stochastic parallel translation.
Currently I am working on a portable pneumatic powered ankle-foot orthosis (PPAFO). My work on this device involves the mechanical design updates needed for the newest version, including improved functionality and efficiency. I also am planning to use the PPAFO for stroke rehabilitation in the future.
We have recently reported a series of N-hydroxyindole (NHI) compounds as a novel class of lactate dehydrogenase A (LDH-A) inhibitors. The glycolysis enzyme LDH-A represents a novel and selective anticancer target since it is crucial in allowing cancers to maintain their highly-glycolytic metabolism (the Warburg effect), survive in hypoxic conditions, and maintain an acidic tumor microenvironment to help evade immune response. LDH-A overexpression has been correlated with poor prognosis and survival in a diverse array of human cancers, and emerging research presents compelling evidence for LDH-A inhibition as a tractable anticancer strategy.
My dissertation research involves the biological assessment of diverse classes of LDH-A inhibitors, including assessment of compounds’ anticancer potency, cellular lactate production inhibition, cellular permeability, and selectivity. I am also elucidating the metabolic and transcript profiles of various classes of reported LDH-A inhibitors. These cell culture characterization studies, along with ongoing animal studies using these compounds, will and push these compounds toward cancer clinical trials as well as broaden our understanding of LDH-A’s role in cancer biology.
The long-term objective of our efforts is to identify treatment options that decrease tinnitus-related distress. Our aims are (1) to identify any existing relationship between tinnitus severity and physical activity and (2) to characterize the differences between tinnitus subjects with varying physical fitness and tinnitus severity levels using both behavior and brain imaging tools. Our hypothesis is that physical activity will be negatively correlated with tinnitus severity scores, and brain function and structure will be different between individuals with tinnitus based on fitness level. Several studies have shown fitness to be correlated with lower depression scores and improved perceived quality of life (QOL) in a plethora of populations; however, there is an absence of studies have made similar connections with respect to tinnitus-related distress. Therefore, to assess the relationship between physical fitness and tinnitus severity we will conduct the following study. First, we will distribute surveys via Survey Monkey to hundreds of individuals with tinnitus to assess the relationship between tinnitus severity and physical activity. Second, we will estimate the differential effects of fitness level and tinnitus on behavior, brain function and structure, as related to emotional processing. To assess physical fitness level, maximal oxygen uptake scores will be obtained from each subject at the Exercise Psychology Laboratory. We will use a 3T Siemens Allegra MRI scanner with a sparse sampling technique to measure brain function and brain structure with minimal scanner noise interference. The understanding attained as a result of the study will advance the understanding of the neural bases of tinnitus in general, and specifically, the effects of physical fitness. The knowledge gained from the study will also demonstrate the feasibility of using exercise as an intervention for tinnitus.
Heart disease consistently remains the leading cause of death in the United States, leading to nearly 30% of deaths in 2009. The adrenergic receptors, essential for our "fight or flight" response, play a key role in regulation of heart rate, contractility and cardiac growth and are at the center of the pathophysiology behind heart disease. As the complexity of adrenergic signaling pathways within the heart grows, the importance of signaling cross-talk between receptor signaling pathways within the heart remain relatively uninvestigated. My research focuses on elucidating the mechanisms of adrenergic receptor cross-talk and its role in cardiac myocyte death, hypertrophic cell growth and ultimately heart failure. The overall goal is to gain a better understanding of the mechanisms by which current pharmacotherapy prevent cardiac remodeling while improving heart function and to eventually optimize this therapy.
We recently finished a research paper on the implementation challenges of Patient Protection and Affordable Care Act (PPACA, a.k.a Obamacare). It focuses heavily on the constitutionality of the individual mandate and the medicaid expansion to the states. We plan to expand our research to a study of the history, efficacy, and policy considerations towards government mandates in general.
We are also working on a book that explores the way the public learns about various health issues (i.e. harms of smoking, AIDs, Needle Exchange programs, obesity, etc.).
My broad research interests include rural health care, access and availability issues for underserved communities and rural families with developmental disabilities. I work with The Autism Program (TAP, http://www.theautismprogram.org/uiuc.asp) on social-behavioral aspects of autism, diagnostics, and other services in and around Champaign-Urbana and hope to incorporate research on mobilization of the autism movement in rural Illinois.
For my dissertation, I will be drawing upon postmodern seventh and eighth movement constructs of "otherness and difference," critical race theory, queer theory, politics of difference, resistance and identity, and hooks' critical feminism to help construct an alternative, qualitative, discourse of what it means to be living with an autism spectrum disorder in rural Illinois - and how these experiences affect family health and wellness.
Choice frameworks of the semester include: interpretive interactionalism, postmodernism, postpostmodernism, queer theory, critical race theory, critical feminism, politics of difference, social responsibility, community health development (CHD), and community mobilization.
We are interested in exploring the effects of neonatal infections on hippocampal growth and function, focusing on learning and memory. We are utilizing a piglet model as pigs have a very similar brain growth trajectory as humans. Effects from immune system activation in response to infection have been shown to decrease learning and memory function. We are interested in how an infection during the neonatal time period affects development of the hippocampal system at a cellular level, and how these changes affect short and long-term behavioral outcomes. We are also interested in adapting additional behavioral tests to the piglet model to measure behaviors seen in autism and schizophrenia patients in order to explore whether neonatal infections have a role in the development of these behaviors.
My research is in micro- and nanotechnology applications for disease diagnostics in resource-limited settings. Specifically, we are working on devices that will perform CD4+ T Cell counts and HIV viral load - two important tests for patients with AIDS - at the point of care. Our technologies are designed to be low-cost, simple and easy to use, performing label-free electrical-based measurements on a small platform where otherwise complex assays are performed that require large equipment requiring a highly-trained technician to operate.
Parents have been considered an underutilized resource for educating children about HIV prevention. Parents and other family members can play a critical role in prevention efforts by using effective parenting practices, communicating their values and expectations, and modeling strategies that reduce the risk of acquiring HIV. Despite the potential protective role of parent-child communication on adolescent sexual and drug use behavior, much remains unknown about the processes and contexts in which these communication encounters occur. My research examines parent-adolescent communication about HIV prevention in families affected by HIV. Specifically, my dissertation project will use a mixed methods approach to identify the strategies parents living with HIV/AIDS use to discuss HIV prevention with their 10-17 year old adolescents. Whereas in-depth interviews will shed light on what motivates and/or prevents parents from discussing HIV prevention with adolescents, a questionnaire will collect information on theoretical concepts previously identified as important to research in this field. Overall, the specific aims are as follows: 1. to describe the strategies parents living with HIV/AIDS use to communicate about HIV prevention 2. to compare parents' perceived effectiveness of those strategies to what current health communication/ health behavior research deems effective parent-adolescent communication, and 3. to identify barriers and facilitators to talking about HIV prevention in a family context, particularly those that may be unique to families affected by HIV/AIDS. This research will be useful in identifying ways to help parents more effectively communicate with adolescents about safer sex, drug use, and HIV infection.
Kristen Ann Ehrenberger's dissertation, "The Politics of the Table: Nutrition and the Telescopic Body in Saxon Germany, 1890-1935," explores how and why nutrition was so important, not just for individual health, but for the collective well-being of Germans in the early twentieth century. Through exposure to debates about proper nutrition in sources such as cookbooks, scientific journals, women's magazines, and traveling museum exhibitions, Germans developed a way of thinking I call the “telescopic perspective” that combined a positivist belief in the ability of medicine to heal social ills with a tendency across the political spectrum to think of the nation as an organic whole. The resulting “telescopic body” connected Germans as a sometimes metaphorical, sometimes biological entity all the way down to their cells.
Having successfully defended her dissertation in Spring 2014, she will complete her undergraduate medical education in May 2016 and looks forward to specializing in developmental pediatrics. Kristen Ann Ehrenberger is also co-author of _Individual and Collective Memory: Analogous Processes on Different Levels_ (MIT Press, 2012) with Tom J Anastasio, Patrick Watson, and Wenyi Zhang.
Several genes linked to Salmonella enterica serovar Typhimurium virulence are carried by the active phage, Gifsy-1. Gifsy-l is located at 57 units of the Salmonella genetic map and it is related to bacteriophage Lambda by sequence homology. This homology includes the Integrase (Int) of the Gifsy-l phage which belongs to a highly conserved family of tyrosine recombinases. Gifsy-l Integrase catalyzes site specific recombination between a bacterial attachment site (attB) and a phage attachment site (attP). Gifsy-1 Excisionase (Gifsy-1 Xis) is presumed to act as an accessory protein which participates in the formation of a protein-DNA complex including Gifsy-1 Int, IHF, attL, attR, and Xis to accomplish excisive recombination.
Gifsy-1 Xis is a small (94 amino acids), strongly basic (pI of 10.2), DNA-binding protein. Results of mutagensis experiments suggest Gifsy-1 Xis is necessary for the formation of a functional excisive recombination complex and in addition nearly the entire length of the Xis protein is required for proper function. Mutations deleterious to Xis function were isolated in a highly basic N-terminal region and a short proline-rich putative linker region. These results suggest that though Gifsy-1 Xis possesses a drastically different primary amino acid sequence its secondary domain organization might resemble that of the Xis protein of Lambda phage. However, Gifsy-1 Xis retains little homology to any known protein so the mechanism by which Gifsy-1 Xis interacts with its target DNA sequence and the Gifsy-l Int protein remains unknown.
To identify the specific attP region to which the Gifsy-1 Xis protein binds Electromobility Shift Assays (EMSA) and several footprinting techniques were used. A 160 base pair region was identified by EMSA and further dissected using DNase I and Dimethyl Sulfate footprinting techniques. Dnase I protection assays identified a 40 base pair region lying approximately 100 base pairs from the site of Gifsy-1 Int mediated strand exchange that is specifically protected by Gifsy-1 Xis. Methylation protection experiments revealed that some residues in the major groove of this region make close contacts with the Gifsy-l Xis protein and also inhibit binding in DMS interference assays. This pattern of Gifsy-1 Xis binding differs from the pattern of the well characterized Lambda Xis protein and may suggest that Gifsy-1 Xis functions in a different manner than Lambda Xis.
We would like to study the earliest molecular events that occur during tumor progression. We believe that these events are governed by the tumor stroma, or microenvironment. We developed novel three-dimensional cell culture models for understanding how tumor cells interact with fibroblasts, the predominant cell type present in the tumor stroma. Fourier transform infrared (FT-IR) spectroscopic imaging is used to translate results from cell culture samples to patient tissues, and to describe label-free chemical signatures of disease progression.
We have developed a method to both understand the molecular mechanisms involved in how the microenvironment regulates early breast cancer phenotypes and to detect altered cellular phenotypes using label-free FT-IR imaging. We aim to apply this systems pathology approach to the development of novel diagnostic and prognostic signatures for determining the trajectory of cancer progression at very early stages.
Telomeres are nucleoprotein structures that cap and regulate the ends of chromosomes. In cancer cells, telomerase, an enzyme that extends the telomere, is overactive which leads to the immortal phenotype. We have developed a platform to study the structural dynamics of the telomere and its interactions with the associated telomere binding proteins.
The innate immune system acts as the first line of defense against infection and plays a primary role in the immediate response to microbial infection. The Toll-like receptors (TLRs), along with numerous other pattern-recognition receptors, are integral players in mediating the recognition of microbial products. This recognition leads to an inflammatory response and increased expression of molecules required for adaptive immune activation. Ten TLRs are found in humans and have been shown to recognize components of the bacterial cell wall, intracellular nucleic acid agonists, as well as endogenous agonists released during tissue damage and stress. The role of TLRs in cardiovascular disease and airway inflammation have been implicated by important links between single-nucleotide polymorphisms in TLR4 and TLR2 and the formation of atherosclerotic plaques, as well as both the incidence and severity of asthma. TLR2 requires either TLR1 or TLR6, and this ability to form functional heterodimers enables TLR2 to recognize numerous molecular agonists. TLR10 had been deemed an orphan member of the TLR family. The great challenge in the study of human TLR10 is the lack of a functional homologue in mice and its relatively low level of expression in most
cells of the immune system, with the exception of memory B cells which have been shown to express significant levels. Using synthetic molecular agonists to activate TLR10 signaling, the goal of my project is to investigate the signaling outcomes of TLR10 stimulation. We propose to generate human and mouse cell lines that express exogenous TLR10 and compare the gene expression profiles of these lines with that of empty vector controls. We will then validate our findings using quantitative PCR and ELISA methods. Lastly, we will investigate the signaling mechanisms used by the TLR2/10 complex by identifying adaptors and interactions required for signal transduction. The identification of key signal transduction pathways used by TLR2-subfamily heterodimers has the potential of uncovering important therapeutic targets against chronic inflammation. In addition, this work will contribute to the goal of developing a clearer molecular understanding of the mechanisms of health and disease, in addition to shedding light on the role of inflammation, immunity, and infection on the pathophysiology of cardiovascular and lung disease.
We are interested in applications of micro and nanotechnologies, especially thin films, microspheres, and nanoparticles. My work focuses on the development of gelatin nanoparticles for targeted drug delivery for use in the treatment of epilepsy and other neurological disorders.
Ischemia is the underlying pathology of many diseases which lead to poor circulation, necrosis and eventual loss of function. The progression of vascular occlusive diseases, more specifically, often result in insufficient oxygenation and claudication or critical limb ischemia (Schirmer and Royen 2004). In an effort to combat the effects of these diseases numerous attempts to induce angiogenesis and arteriogenesis, as a means of collateral blood supply, have been made. While cellular/molecular (Messina et al. 2002, Guan et al. 2007) and genetic (Jiang et al. 2007, Hung et al. 2007, Hiasa et al. 2004) endeavors continue to be pursued, these have not translated well into the clinic as apparent by the multitude of literature, but persisting complications. Ultrasound has been reviewed for its therapeutic effects since the early 1960s (Paul et al. 1960, Galitsky et al. 1964) and continues to show promise for angiogenic induction in ischemic tissues both without (Barzelai et al. 2005) and with the use of contrast agents (Song et al. 2002, Song et al. 2004, Chappell et al. 2005). Other literature combines the genetic/cellular methods with ultrasound contrast agents (UCAs) to promote the biological effect (Price et al. 1998, Zen et al. 2006, Korpanty et al. 2007, Leong-Poi et al. 2007).
While there are some central dogmas for exposure conditions to encourage collateral growth (i.e. low frequency, low pressure), the pulsing conditions, use of contrast agents, intensities, and the observed date at which angiogenesis is observed all vary. Because of the discrepancies in the literature, it is difficult to draw conclusions about possible exposure conditions in patients. The already existing phenomena of ultrasound contrast agent induced angiogenesis needs to be validated if this therapeutic application is to transition to the clinic. For patients with vascular occlusive disease, not only do general trends need to be elucidated, but also the biophysical mechanism behind the therapy. Therefore, the first objective of this study is to develop an understanding of the angiogenic progression in UCA-treated normal muscle via a survival study. In doing so, the underlying principles of exposure conditions will be used to assess the response. This information will be used for the second objective: to understand the role of the UCA in inducing neovascularization (at the peak time point for angiogenesis). Finally, the mechanism by which ultrasound and ultrasound contrast agents exert their effect will be explored using the angiogenic marker VEGF, quantitative real time PCR for VEGF mRNA expression, inflammation, and capillary density as quantifiable end points.
I'm focusing on how infection with H. pylori can induce the activation of transcription factor NF-kB in gastric epithelial cells.
Spinal muscular atrophy (SMA) is an inherited disease that affects ~1 in 6,000 live births, and is characterized by loss of spinal cord alpha-motor neurons, the inability to sit, stand, or walk, and often infant mortality. Milder forms of the disease allow for longer lifespans, but patients are still unable to stand or walk. The disease has been linked to the loss of the Survival of Motor Neuron (SMN1) gene, which encodes for the SMN protein. A nearly identical gene, SMN2, encodes for an essentially identical protein that differs by a single nucleotide mutation, leading to a truncated protein that is quickly degraded. The reason for this degredation has been linked to alternative splicing, a mechanism by which a single gene can produce many protein forms.
My projects involves the use of small molecules (dendrimer molecules and peptides) that are targeted specifically for this mutated sequence in order to restore proper splicing and production of the full protein. In doing so, we will provide a potential therapy for patients diagnosed with SMA.
Horizontal gene transfer of conjugative transposons has been implicated as one of the major causes in the spread of antibiotic resistance in Bacteroides species over the last 30 years. CTnDOT is one such conjugative transposon, which carries resistances to both tetracycline (tetQ) and erythromycin (ermF). It also encodes its own integrase - IntDOT, which is essential for excision and integration both in vivo and in vitro. While IntDOT is classified as part of the tyrosine recombinase family, it is unique in that it does not require complete homology within its coupling sequence. Recent studies show that the integrase cleaves 7bp apart rather than 5bp as previously thought. These two extra bases provide the only known homology required for integration. The goal of this project is to further characterize IntDOT using an in vitro integration system. Sequence and homology requirements for integration will be determined by mutational analysis of the attB and attDOT regions.
As part of the Nano Sensors Group, I work on two projects using optical techniques to measure biologically relevant samples. I currently use a Photonic Crystal Enhanced Microscope to study non-invasively the cell-substrate interactions of adherent cell lines to investigate important processes such as stem cell migration and cancer cell metastasis. Additionally, i work to use a smartphone based biosensor developed as a mobile spectrometer to perform traditional laboratory assays in non-laboratory settings.
Due to genetic abnormalities, traumatic injury, or cancer, there is a large population of patients with bone defects too large to heal on their own. The current gold standard of treatment is the autograft: harvesting bone tissue from another area of the body in order to begin the healing process. However, complication rates for these multiple surgeries are high, and the harvested site is also more vulnerable to fracture.
Adult stem cells, capable of differentiating into bone, cartilage, fat, and even nerve cells, provide great hope for the field of tissue engineering, whose goal is to engineer tissues and organs which replace diseased organs and cannot be immune-rejected. Scaffolds provide a geometrical framework for these cells to construct tissue proportionly and the addition of growth factors increases the rate of healing.
My project uses adult mesenchymal stem cells derived from fat, which is relatively simple to acquire from liposuction. Hydroxyapatite scaffolds are similar in composition to bone, and bone morphogenic protein is a powerful growth factor for new bone synthesis. These materials will be surgically implanted into the jawbone of pigs with large bone defects to ascertain and further refine the ability of these materials to synergistically improve bone healing. The goal of this project is to develop a product that is ready for human clinical trials.
My research focuses on the analysis of neuropeptide release in rodent models utilizing various techniques along with mass spectrometry. The animal model used in research to study fragile X syndrome (FXS), the most common cause of inherited mental retardation, is the Fmr1 knockout (Fmr1 KO) mouse. FXS is characterized by moderate to severe mental retardation, macroochridism, attention deficit, hyperactivity, and behaviors characteristic of autism. My research has shown that there is a neuropeptide release deficit in the brains of Fmr1 KO mice. This is a novel finding in the FXS field. The goal of my project is to further examine deficits in neuropeptide release as a possible cause of the neurobehavioral abnormalities in FXS. In addition, I also examine neuropeptide release in the rat hippocampus in response to maze training and acute drug exposure. The technique used is microdialysis. This is a novel technique to analyze neuropeptides in the brain and the goal of this project is to find peptide biomarkers released during learning and/or drug exposure. The overall goal of my research is to expand on novel peptide analysis techniques that will be useful in brain research.
The recent deep economic recession and increases in unemployment in the United States have renewed the debate over the social and economic effects of immigration and have fueled debates over immigrant deservingness. Today, immigrants are faced with controversial state and local policies aimed at massive detention and deportation, continued exclusion from healthcare reform, and hostile attitudes towards racialized immigrant groups. Consequently, immigrants today are experiencing heightened fear, stress, instability, and greater social marginalization.
Yet, little research exists on how the complexity of immigration affects the health and well-being of U.S. immigrant communities. Many large-scale studies and datasets still lack the important indicator of nativity, and no major studies of health examine the influence of complex immigration-related factors such as documentation status, liminal legality (e.g. uncertain or temporary documented status), pre-migration stressors, traumatic migration experiences, transnational social ties, local and state immigration policies, and social marginalization and discrimination based on anti-immigrant climates. Moreover, the dominant theoretical approach to immigrant health converges around cultural explanations for health outcomes, especially on acculturation. This approach ignores the socio-historical contexts of migration, immigrants’ experiences of social and economic inequalities, racialization processes, social marginalization and discrimination. Subsequently, there is a clear paucity of theoretically-driven critical research on immigration and health.
This project utilizes the idea of embodiment to examine the social processes that undocumented Latino/a immigrants undergo and how these social processes affect health. Embodiment refers to how our bodies and minds literally incorporate, from conception to death, the material and social world in which we live. The project uses original qualitative in-depth interviews, focus group interviews, and discourse analysis to understand: how undocumented Latino/a immigrants experience structural violence (e.g. labor exploitation, poverty, discrimination and social marginalization); how undocumented Latino/a immigrants contend with imposed racialized, classed and gendered representations; and how inequality becomes expressed as stress, physical and mental health outcomes.
The photosynthetic reaction center (RC) converts light to chemical energy. Its protein structure acts as a scaffold for a series of electron transfers leading to reduction of the primary quinone (QA) followed by reduction of the secondary quinone (QB). In Rhodobacter sphaeroides both QA and QB are ubiquinone-10 (Q-10). For favorable electron transfer to occur between two chemically identical molecules the local environments must alter their midpoint potentials, i.e. the protein tunes the quinone midpoint potentials (EM). Site-specific mutagenesis of amino acids involved in QA binding has identified some residue with strong influence of the EM. Mutation of IleM265, to either threonine or serine (M265IT or M265IS) produces a drop in the EM by 100mV and 85mV, respectively. However, mutation of IleM265 to valine does not significantly affect the EM. From computer modeling it is proposed that a change in the length of the hydrogen bond between the M260 backbone amide and the carbonyl group at position 1 of QA is the major cause for this change in EM. This requires a specific orientation of the side-chain OH-group of ThrM265 and SerM265, to hydrogen bond with the backbone carbonyl of M261. This new hydrogen bond is proposed to cause the backbone perturbation leading to the change in hydrogen bond length of M260. Currently attempts to grow crystals of these mutants are underway to test this hypothesis. Further, the Wraight lab has found that substitution of Q-10 with synthetic mono-methoxy ubiquinones only allows reduction of QB when the methoxy at the 2-position on the quinone headgroup is present. Currently we are examining structurally why this may be using flash spectroscopy and crystallography.
T cell receptors (TCR) recognize peptide antigens presented by proteins of the major histocompatibility complex (MHC) in a highly specific manner. Exotoxins, secreted by bacteria, are members of a class of proteins known as superantigens (SAg) that bind to the TCR in a different manner than normal antigen. The binding of these toxins to the TCR and the MHC causes massive T cell activation initiating a 'cytokine avalanche', ultimately leading to tissue damage and even lethality. One of these toxins, Staphylococcal enterotoxin C3 (SEC3), has also been linked to diseases including necrotizing pneumonia, Kawasaki and Idiopathic Dilated Cardiomyopathy. An understanding of the molecular mechanisms has driven our efforts to generate specific high-affinity neutralizing agents that could reduce the severity of diseases caused by these toxins. The affinities of Sags for the TCR are low, usually in the micromolar range, allowing for development of a high affinity soluble Vbeta domain that would neutralize Sag activity by competing for the TCR binding site. Several regions that contact SEC3 based on alanine scan mutagenesis and crystal structure analysis are targeted and subjected to numerous rounds of directed evolution using yeast display. Equilibrium and off-rate based selection are used to affinity mature a TCR to higher affinity (picomolar KD value) for SEC3. Soluble forms of the Vbeta proteins are expressed in Escherichia coli and preliminary studies in vitro and in vivo animal models are underway to determine their therapeutic potential against SEC3 toxicity. This high-affinity anti-SEC3 Vbeta protein may serve as a potential treatment for disease mediated by the Sag SEC3.
My disciplinary focus, “Modern Chinese studies”, constitutes a broad field for those in the humanities and the social sciences. One of my current aims is to try to understand how illness and disease (in the context of western, biomedicine) are conceptualized in East Asia. This includes representations in literature as well as professional and specialized developments in Chinese and Japanese neurology and psychiatry since the early 20th century. For example, "neurasthenia" is no-longer a meaningful disease category for western neuropsychiatry, but it is one of the most widely employed diagnostic categories in China today. My studies are one way of approaching the epistemological problems inherent in the philosophy of science and medicine in a cross-cultural context. This pursuit is worthwhile philosophically, but it is also clinically relevant in an increasingly smaller world.
After working in a spine/cerebral palsy clinic and a spinal cord injury lab, I am very much interested in regeneration of the brain and spine. Humans are very bad at regenerating these organs, so I am looking at a creature that has a spectacular regenerative capacity - a little flatworm (non-parasitic :) ) called the planarian. I hope to understand the molecular basis of why it is so good at regenerating its central nervous system and compare it with what goes on in humans.
Two projects that will help to address this question are:
-Find human disease gene homologs in the planarian genome. Use the technique of RNAi to disrupt said genes in the planarian and watch what happens to its ability to regenerate its CNS.
-As above, but with neural stem cell-associated genes.
Hypoxia and hypoglycemia are both important problems encountered in the clinical setting. I am using cell culture models to investigate the pathways responsible for the effects of hypoxia and hypoglycemia in various organ systems.
Memory impairments accompany aging and can range in severity from very mild deficits to debilitating conditions such as Alzheimer's disease. The causes of these impairments are generally viewed in terms of anatomical, chemical, and physiological changes within the brain. However, alterations in peripheral neuroendocrine systems may also contribute to these deficits. Previous work in rodents and humans indicates that increases in blood glucose in response to endogenous epinephrine release are important for regulating memory formation and durability. Blood glucose likely modulates memory processes by augmenting the supply of glucose to specific regions of the brain during cognitively demanding times. Recent evidence suggests that, in old rats, glucose is less responsive to epinephrine and becomes severely depleted in the extracellular fluid of the hippocampus during a spatial working memory task, contributing to age-related memory impairments.
This work examines potential mechanisms by which age-related deficiencies in brain glucose availability lead to memory impairments. Several findings suggest that fluctuations in glucose levels in the extracellular fluid may modulate memory processes by altering the release of the neurotransmitter acetylcholine. This in turn may affect downstream processes important for the formation of durable memories. In particular, nicotinic acetylcholine receptor signaling mediates the calcium-dependent activation of the ERK/MAPK and CREB signaling cascades, which are widely implicated in activity-dependent neuronal plasticity. Age-related deficits in brain glucose availability may limit these cholinergic signaling processes and produce memory impairments. This is the major hypothesis guiding these studies.
I am interested in drug addiction and exercise-induced hippocampal plasticity. Currently, I am interested in elucidating the mechanisms by which exercise can facilitate extinction of conditioned place preference for cocaine in C57BL/6J mice.
Exercise has been proposed as a potential intervention for drug addiction because it has been shown to weaken drug-to-context learning, possibly because it promotes brain plasticity and may serve as a substitute reward. I am currently using a novel transgenic mouse model in which thymidine kinase expression is coupled to the nestin promoter and am delivering the drug Ganciclovir in mini-pumps I surgically implanted in mice. In the presence of the thymidine kinase enzyme, the prodrug Ganciclovir is phosphorylated and causes apoptosis of dividing cells. The nestin promoter is exclusively expressed in neural progenitor cells. Therefore, the goal of using the mouse model is to ablate hippocampal neurogenesis and to determine whether the hippocampal neurogenesis induction of exercise is requisite for exercise's ability to weaken conditioned place preference for cocaine. I am also assessing levels of neurogenesis in the dentate gyrus using BrdU, NeuN, and S100β with the goal of confirming ablation of hippocampal neurogenesis in the Ganciclovir-receiving transgenic mice. Ultimately, I hope to better understand mechanisms by which exercise can weaken drug-to-context learning.
The actin cytoskeleton is a key component of cell structure necessary for many cellular processes such as cell division and cell motility. Actin exists at concentrations inside cells that favor assembly and pose serious challenges to disassembly; in fact, we currently do not know how the cell is able to disassembly actin filaments under physiological conditions. This proposal aims to understand physiological actin dynamics by identifying and characterizing the factors responsible for the least understood side of the actin cycle: disassembly. Such an understanding would have a major impact on any area of clinical or pre-clinical research where cellular problems are actin-dependent; one such area is nephrology. Genetic analysis has found actin-binding proteins prominent among those proteins responsible for familial kidney disorders: -actinin and formins in focal segmental glomerulosclerosis and filamin and other actin bundling protein in polycystic kindney disease. We have identified two previously unappreciated proteins using an activity-based biochemical reconstitution that augment the previously characterized cofilin-, coronin-, and AIP1- mediated actin depolymerization system. Cyclase associated protein (CAP) allows this triple-protein mix to depolymerize a fluorescent actin substrate in the presence of cellular concentrations of polymeric and monomeric actin when alone the triple-mix can only deal with physiological monomeric actin concentrations. We propose to use a range of techniques including fluorescent microscopy of bulk actin arrays and electron and fluorescent microscopy of single actin filaments to better characterize the mechanism by which this reaction is accomplished. Somatic nuclear autoantigenic sperm protein (sNASP) functions similarly to AIP1, though further analysis of this similarity is needed. While AIP1 is a cytoplasmic protein, sNASP is a nuclear protein that we have identified as an actin disassembly factor, and since it is known to bind histones and function in chromatin remodeling it represents a possible link between the cytoskeleton and chromatin structure. We plan to use many of the same techniques to characterize sNASP as we will use to characterize CAP, with additional genetic manipulations to test AIP1 and sNASP redundancy in vivo.
My research interest lies in the integration between the dynamics of social interaction and the physiological aspects of human development. My primary concern is to delineate the variations in health outcomes of individuals exposed to intimate partner violence (IPV), particularly in the scope of child exposure to IPV between parents and its behavioral and neurological effects on child development.
I am currently working with Dr. Jennifer Hardesty on a study that examines coparenting relationships after separation within an IPV framework. Through the recruitment of 120 recently separated mothers, we seek to outline the distinct patterns of such relationships in mothers who had either a violent or nonviolent history with their former partners. In addition, we aim to ascertain specific protective and risk factors associated with these relationships. Finally, we will be observing the specific physical and psychological health outcomes that such variations in coparenting relationships have on mothers and their children. This study utilizes a conceptual model that integrates two distinct theories; IPV and coparenting after separation. It is this study's hope that such an integrative approach will provide a greater understanding within the public and health care arenas of the important role in which IPV plays in a mother's well being, even after legal separation from the former partner.
My research is involved in the development of new biosensing modalities for improved disease diagnostics and personalized medicine. In particular, I utilize arrays of silicon photonic microring resonators as a platform for the detection of nucleic acids. These sensors are incredibly inexpensive, and offer extraordinary sensitivity and multiplexed capabilities.
This project will explore the role of the physician in medical humanitarian aid organizations. In particular, the author will look at the ways in which local and foreign physicians negotiate power and identity within these organizations and how these elements contribute to citizenship for these doctors. In addition, it will explore the manner in which the physicians' relationships within the organization affect access to care issues for patients.
Dynamic languages such as Python, Perl and Ruby are making programming easier for a wide variety of users across disciplines. However, code written in these languages runs more slowly than those in harder-to-use programming languages such as C and Java. I am exploring hardware-software mechanisms for improving the performance of dynamic language runtimes, so that they run faster and can be more widely applied.
Glia have long been positioned as the support system of the neuronal brain, but beyond this function, their role has been poorly understood. Glia of the mammalian suprachiasmatic nucleus (SCN) in particular have been understudied, and their identity is only now being elucidated. One of the least studied aspects of glial cells is morphology, and SCN glia morphology is not well characterized. If SCN glia serve a circadian function, they should then demonstrate measurable changes over a circadian cycle, and in particular, changes in cell morphology. I have evaluated the dynamics of SCN and hippocampal dentate gyrus glial cytoskeleton morphology in rat coronal brain sections over circadian time using confocal fluorescence microscopy.
Whether to promote neuron health and synaptic communication or to serve otherwise unknown purposes in glial networks, the consequences of glial plasticity in brain physiology are inarguably profound. If the contributions of neurons to neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and multiple sclerosis are relatively undetermined, then the contributions of glia to these diseases are vastly unknown. Glia almost certainly serve a greater role in daily physiology than previously conceived, but more importantly, their malfunction may serve as the basis for serious pathological states. Understanding how glia operate from a morphological perspective may provide a deeper understanding of central nervous system disease.
I have quantified binding sites in acetylcholine receptors using single-molecule fluorescence microscopy techniques.
I have developed new methods for achieving super-resolution fluorescence imaging. That is, standard microscopy limits imaging resolution to about 200 nm, due to the diffraction limit of light. Our techniques allow resolution to be on the order of 20 nm or better.
Over the past few decades, our knowledge of tumor immunology and the role antitumor immune responses play in tumor recognition and eradication has greatly increased and led to immunotherapies being investigated as a promising strategy for cancer treatment. Current clinical studies with various immunotherapies have shown promising results, including adoptive cell transfer (ACT) of T lymphocytes. Adoptive transfer of T cells is highly attractive because T cells are able to penetrate tumors and selectively recognize and destroy neoplastic cells. Although a promising approach, one of the limitations encountered clinically is the difficulty isolating and expanding tumor-specific T lymphocytes from patients. This limitation may be circumvented by genetically engineering T lymphocytes to express antigen-specific T cell receptors (TCR).
We generated a SIYRYYGL (SIY) peptide-expressing murine glioma cell line (GL261-SIY), which is recognized by 2C T cells, as a model to investigate strategies to improve adoptive T cell therapy for brain tumors. We characterized the GL261-SIY cell line in vitro and assessed ACT of transgenic and TCR-transduced T cells in vivo with GL261-SIY brain tumors. Our findings show normal cell surface levels of SIY antigen expression and effective peptide presentation to T cells in vitro resulting in T cell activation (IL-2 cytokine secretion) and induction of cytotoxic T cell activity. We have also investigated whether ACT with CD4+ helper T cells enhances antitumor effector functions of CD8+ cytotoxic T lymphocytes (CTL) for cancer therapy. Adoptive transfer of T cells genetically engineered with tumor antigen-specific T cell receptor (TCR) gene therapy was evaluated in a subcutaneous malignant murine melanoma tumor model. We tested the feasibility of transducing primary murine T cells with gene modified TCRs and assessed their functional activity in vitro. Additionally, results from our studies show long term antitumor effects on survival of melanoma tumor-bearing mice with T cells transduced to express genetically engineered TCRs. Our overall goal is to determine whether CD4+ helper T cells transduced to express engineered high affinity TCRs will synergize with CTLs to enhance T cell immunotherapy and eliminate malignant tumors such as glioma and melanoma.
Polyphosphate (polyP) is located within human platelets and is released on platelet activation, where it works to accelerate the clotting process by acting as a surface “template” for a number of clotting reactions. This acceleration effect is more important for pathological thrombosis (i.e. heart attack or ischemic stroke) than for hemostasis (normal response to vessel injury). Interestingly, bacteria also contain polyP and because it is of a much longer size than platelet polyP, it can not only accelerate blood clotting (like platelet polyP) but also activate the immune system as well. Thus molecules that are able to inhibit polyP are attractive candidates for a completely novel class of safer and more effective antithrombotics and anti-inflammatory agents. In my research I use in vitro screening techniques and clinically relevant mouse models of thrombosis and inflammation to study the ways polyP contributes to disease progression. In addition to elucidating novel modes of action for platelet and bacterial polyP in vivo, these studies aid in the development of a novel class of polyP inhibitors discovered in our laboratory. These compounds will be the first generation of a new class of therapeutics aimed at targeting polyP clinically to prevent polyP-mediated contribution to the pathological process of a number of potential diseases, including heart attack, ischemic stroke, sepsis, and disseminated intravascular coagulation, in a safe and effective manner.
My research focuses on the cell signaling mechanisms that influence skeletal muscle development. Mature skeletal muscle tissue contains a resident population of stem cells that imparts a great capacity for regeneration. Upon injury, these satellite cells are reactivated and begin to proliferate to dramatically increase myoblast numbers. Effective myogenesis depends on the daughter myoblasts successfully differentiating and fusing with each other to regenerate the characteristic multinucleated skeletal myofibers. Dysregulation of these processes can have severe consequences, including disease states like the muscular dystrophies and cachexia. However, despite the great deal of potential clinical gain in understanding myogenesis, the complex mechanisms underlying skeletal muscle dynamics are still poorly understood.
Cell-secreted factors, such as cytokines and chemokines, represent one possible source of myogenic regulation. It is generally accepted that those factors influencing muscle cell regeneration in vivo are largely of immune cell origin. However, various mass spectrometry analyses have shown muscle cells to be prolific secretors of a wide variety of proteins. These observations point toward the intriguing possibility that muscle cells secrete cytokines that influence their own development and regeneration. To investigate this idea, we conducted an shRNA screen of myocyte-secreted factors that play a role in muscle differentiation. We found 30 cytokines and chemokines that positively or negatively regulate myogenesis, several of which are currently under investigation for their role in skeletal muscle regeneration in vivo.
I am studying the role of a newly discovered neurodevelopmental gene, Auts2, in abnormal neurodevelopment. Mutations in the Auts2 locus cause autism, epilepsy, and mental retardation in humans, but little is known about the function of this gene or its role during neurodevelopment. I am analyzing the role of AUTS2 in differentiation of neurons in culture to ask what the function of AUTS2 is in normal neurodevelopment. As well, I utilize a unique translocation mutant called 16Gso which displays epilepsy and autistic-like behaviors resulting from a reduction in AUTS2 expression to how AUTS2 disruption can lead to abnormal neurodevelopment.