State-of-the-art upper limb prostheses are severely limited in their ability to provide sensory feedback to a user. The lack of sensory feedback forces prosthesis users to rely on visual feedback alone in manipulating objects, and often leads to abandonment of the prosthesis in favor of the user’s unimpaired arm. Consequently, there is a critical need to develop mechanisms that enable people with upper limb amputations to be able to receive sensory feedback from the environment. Through the use of techniques like targeted reinnervation, there has been significant progress in providing patients with intuitive neural control of their prostheses as well as sensory feedback. Studies have shown that patients receiving sensory stimulation over reinnervated sites while operating a prosthesis more strongly incorporate the artificial limb into their body schema. However, there is limited cutaneous space available over the reinnervated sites for both EMG sensors and stimulators to be placed. As a result, the overall objective of the proposed research is to clinically evaluate a flexible, stretchable epidermal electronic device that conforms to the skin and can simultaneously record EMG and provide electrotactile sensory stimulation at high density over reinnervated sites. We hypothesize that long-term, closed-loop sensorimotor control in prostheses enabled by epidermal electronics will improve fine motor control and promote incorporation of the prosthesis into the body schema, ultimately reducing prosthesis abandonment. We will address this hypothesis through the following Specific Aims, in which we will 1) optimize and validate a single flexible epidermal device that can both acquire EMG and provide electrical stimulation simultaneously at high density, 2) develop methods for automatic calibration and modulation of electrotactile sensation intensity to enable long-term wear, and 3) improve fine force control, object recognition, and embodiment through the use of sensory feedback. In turn, we expect that daily usage of prosthetic devices will increase due to the incorporation of high resolution sensory feedback.
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.
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.
Non-alcoholic steatohepatitis (NASH) is emerging as one of the most common liver disease in the American population. It is a metabolic disorder in which fat accumulation within the liver (steatosis) is associated with inflammation, hepatic injury and cirrhosis without significant consumption of alcohol. Recent studies estimate this disease affects roughly 6 – 17% of the general population with increased prevalence in individuals affected with obesity and type II diabetes. Of the individuals affected with NASH, about 20 – 25% develop advanced stages of fibrosis eventually leading to liver failure and death. Current knowledge of this disease is limited because early stages (simple steatosis) of NASH are asymptomatic and difficult to detect. Hence, a robust model system is necessary for rapid progress in understanding NASH etiology, progression and potential therapeutic targets.
Surprisingly, preliminary phenotypic characterization of hepatocyte-specific SRSF1 knockout (SRSF1 HKO) mice show all the hallmarks of NASH; steatosis, inflammation and fibrosis. SRSF1 belongs to a highly conserved SR family of pre-mRNA splicing factors that share two modular protein domains; the RNA recognition motif (RRM) and the serine/arginine dipeptide repeat (RS) domain. Initial in-vitro studies of this splicing factor revealed it was essential for correct 5' splice site selection and cleavage. Further studies of this protein revealed it could modulate splicing in a concentration-dependent manner thus making it an alternative splicing factor. Furthermore, SRSF1 is one of the few members in the SR family of proteins, which also has nucleocytoplasmic shuttling activity. Within the cytoplasm, SRSF1 has been shown to regulate both translation and non-sense mediated decay (NMD) of target mRNAs.
Focus of my research is to 1) identify the gene network regulated by SRSF1 and 2) determine how misregulation of this network results in NASH. To gain insight into these question I use a combination of next-generation sequencing techniques (RNA-Seq and iCLIP-Seq), bioinformatics anaylsis, histology, cell culturing, and various molecular biology techniques.
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.
Currently I am working on a portable pneumatic powered ankle-foot orthosis (PPAFO) test bed. My work on the test bed has involved the mechanical design updates needed for portable testing, including improved functionality and efficiency. We have used the PPAFO to investigate the possibility of gait impairment improvements in persons with Multiple Sclerosis. We have also used the PPAFO test bed to investigate the possibility of reducing the metabolic cost of walking in able-bodied young adults.
The current most frequently prescribed antidepressants, selective serotonin reuptake inhibitors (SSRIs), work 20-50% of the time, at best. Research in the depression field predominantly focuses on inhibition of feedback regulation of the serotonin system. My project, however, utilizes a unique approach by employing the capabilities of two powerful computational tools in order to understand how SSRIs work and how they can be improved by modeling drug-induced adaptations in the brain across a network of nine different brain regions. This modeling approach ties together a tremendous volume of data from the literature that could not otherwise be analyzed without computational tools due to the sheer magnitude and complexity of the information. Specifically, the programming languages I use are MATLAB and Maude, due to their unique capabilities. MATLAB interprets statements as commands and executes statements in the order that they are given, but Maude has the capability of interpreting statements as facts, and can execute statements in all possible orders generating a searchable state space. My preliminary model generated a testable hypothesis involving a combination of an SSRI and a corticotropin releasing factor receptor 1 (CRF1R) antagonist in order to improve antidepressant efficacy under the assumption of the serotonin hypothesis. More recently, I have increased the number of interactions in the preliminary model by increasing the number of connections between the neurons, and have expanded the model to include more data to justify initial receptor levels. My goal now is to update both the MATLAB and Maude versions of the model and get them to agree (as a crosscheck), then run state-space searches with Maude. The current most frequently prescribed antidepressants, selective serotonin reuptake inhibitors (SSRIs), work 20-50% of the time, at best. Research in the depression field predominantly focuses on inhibition of feedback regulation of the serotonin system. My project, however, utilizes a unique approach by employing the capabilities of two powerful computational tools in order to understand how SSRIs work and how they can be improved by modeling drug-induced adaptations in the brain across a network of nine different brain regions. This modeling approach ties together a tremendous volume of data from the literature that could not otherwise be analyzed without computational tools due to the sheer magnitude and complexity of the information. Specifically, the programming languages I use are MATLAB and Maude, due to their unique capabilities. MATLAB interprets statements as commands and executes statements in the order that they are given, but Maude has the capability of interpreting statements as facts, and can execute statements in all possible orders generating a searchable state space. My preliminary model generated a testable hypothesis involving a combination of an SSRI and a corticotropin releasing factor receptor 1 (CRF1R) antagonist in order to improve antidepressant efficacy under the assumption of the serotonin hypothesis. More recently, I have increased the number of interactions in the preliminary model by increasing the number of connections between the neurons, and have expanded the model to include more data to justify initial receptor levels. My goal now is to update both the MATLAB and Maude versions of the model and get them to agree (as a crosscheck), then run state-space searches with Maude.
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 the role of LDH-A 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.
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.
Adult Congenital Heart Disease
We are using Cre-Lox technology to develop cell-specific knockdown mice. For depression-like behavior phenotyping, I have trained these mice on the two-bottle sucrose preference test (for anhedonia) and applied the tail-suspension test (for hopelessness/despair). While I am focused on depression-like behavior, I have also developed expertise in measuring sickness-behaviors using locomotor activity and novel mouse investigation assays. Moreover, I have applied assays for anxiety with the elevated-zero maze, and memory using the novel-familiar mouse discrimination test. In addition to this ongoing behavioral phenotyping, I am starting an experiment to study the differential regulation of the dioxygenases in astrocytes and microglia following acute stress or peripheral inflammation. Finally, I am working on a collaborative project with an investigator at Northwestern University where I am analyzing samples by HPLC for dioxygenase dependent metabolites on tissues samples from human tissues or mice with glioblastoma.
In this mixed methods research, I seek to understand relationships between chronic pain and colonization--a chronic history of US empire that I characterize through ongoing encounters with violence and trauma--in order to inform better care practices and policies for American Indians who do not live on a reservation. Pain is elusive and difficult to conceptualize and operationalize. In addition pain makes particularly apparent health inequalities. American Indians experience an unequal burden of chronic pain and unmet needs related to chronic pain care. Additionally, American Indians often conceptualize their pain as not only physical but also emotional, spiritual, and psychological and are more likely to pursue alternative treatments. Therefore I investigate the chronic pain experience for American Indians, focusing on how chronic pain sufferers who live off-reservation conceptualize their pain`s origin, select particular modalities of care, and cope with an incurable and invisible illness.
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.
Cellular FLICE inhibitory protein (cFLIP) is a FLIP protein originally characterized for its extrinsic anti-apoptotic function. We recently showed that cFLIPL has a second function; it inhibits IRF3 activation. IRF3 is a transcription factor that controls the expression of IFNβ and other anti-viral proteins. It is unknown how cFLIPL inhibits IRF3 activation. The goal of this project is to characterize the mechanism of inhibition of IRF3 by cFLIPL. Our initial approach used over-expression of MAVS, TBK1, or a constitutively active IRF3 mutant, IRF3CA, to trigger IRF3 activation in cells over- expressing wild-type or mutant cFLIPL proteins. IRF3 activation was evaluated by using a luciferase reporter assay. These data suggested that cFLIPL functioned at a step after IRF3 dimerization in the IRF3 activation pathway. Our data showed that the caspase-like domain, but not the DEDs of cFLIPL were sufficient for IRF3 inhibitory function. Further, preliminary data suggest that cFLIPL and the CLD mutant inhibit IRF3/CBP interaction upon stimulation, but cFLIPS lacking the CLD does not. Our current hypothesis is that IRF3/FLIP interactions disrupt IRF3/CBP interactions and as a result the transcription factor cannot bind its promoter target. Further experiments are being conducted to evaluate this hypothesis.
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 over-active leading to an immortal phenotype. We have developed a platform to study the structural dynamics of the telomere, its interactions with the associated telomere binding proteins, and the characteristics of extension by telomerase.
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.
Ischemic stroke is a leading cause of death and adult disability. However, there are few effective treatments currently available and many patients do not reach the hospital in time to receive them. More patient-friendly options to reduce brain damage and improve functional recovery following a stroke are needed. One such solution is to use nanotechnology to deliver a drug intranasally, a method that is simple and convenient for patients. We are interested in studying how nanotechnology can improve a drug's ability to heal the brain following a stroke.
We have previously shown that gelatin nanoparticles can significantly improve the ability of an intranasally administered drug to heal damaged brain tissue following a stroke. However, we do not completely understand which properties of gelatin nanoparticles are most important for improving the healing process. We believe the key factor is the nanoparticle's ability to concentrate a drug in the damaged brain regions. Therefore, we are using mice to study how gelatin nanoparticles travel through the brain and degrade after nasal administration. By better understanding how gelatin nanoparticles behave in normal and damaged brains we hope to be able to further improve the gelatin nanoparticles' ability to heal the brain following a stroke.
I design new means of probing how cells interact with and are affected by their local microenvironment, which consists of other cells, extracellular matrix, growth factors, and proteins as well as the biological, biomaterial, and biomechanical interactions between all involved components. Microenvironmental regulation is known to play a key role in many biological and pathological processes including embryogenesis, homeostasis, and cancer. Specifically, I am interested in understanding the exact cues that regulate liver stem and progenitor cell fate/function during development, regeneration, and disease. Towards this end, I use robotic microcontact printing to deposit hundreds of combinations of biomolecules onto a soft hydrogel and measure cell response to each distinct stimuli. Furthermore, I have developed custom software that automatically analyzes and interprets the large amount of high-dimensional data produced by this platform.
Recent studies I have completed utilizing this platform have deconvolved the combinatorial role of extracellular matrix, TGF-beta, and Notch signaling on the differentiation of bipotential liver progenitors. Ongoing work is focused on extending the capabilities of the platform to encompass genetic manipulations, other organ systems and diseases, and alternative imaging modalities. Last, the fundamental hypothesis-testing enabled by this platform is conducive not only to translation of discoveries to new tissue-engineered constructs but also to clinical diagnosis and treatment selection.
Despite the higher prevalence of stress-related disorders in women, sex differences in susceptibility to stress have not been adequately investigated. The current plan for my PhD research focuses on determining sex-specific differences that affect susceptibility, onset, disorder trajectory, and presentation of stress-related disorders, such as post-traumatic stress disorder. We would like to study differential expression of epigenetic factors, such as microRNA, during important developmental periods, such as adolescence, as well as the effect of life experiences, such as trauma and illnesses, on epigenetic changes.
In this project we are developing a means of detecting, monitoring and treating prostate cancer. Our lab has previously assisted in developing a strategy for therapy, based on silencing the expression of the Receptor for Advanced Glycation End Products (RAGE). This therapy resulted in a RAGE-dependent inhibitory effect on the proliferation of both androgen-dependent and androgen-independent prostate cancer cells, cell death, and diminished tumor size in vivo. Due to the significant heterogeneity of prostate cancer, molecular imaging is expected to play an important role in the evaluation of this disease and predicting the efficacy of therapeutic interventions.
Therefore, this project’s overarching goal is to design a non-invasive RAGE-targeted multimodal imaging agent that will be used in PET/CT and optical imaging to improve the diagnosis of prostate cancer, provide sensitive and selective predictions of the success of anti-RAGE therapies, and enable monitoring of the outcomes of these therapies. We also will use this imaging agent to enhance current surgical processes, by developing an image guided system where a surgeon can visualize and manipulate a tumor with 3-D PET/CT images to optimize his surgical route and efficiency and also optically image the tumor in vivo during the surgical process. We hypothesize that non-invasive hybrid PET-CT imaging with RAGE-targeted probes, in combination with both postmortem histochemical analysis of the RAGE, and the development of our novel image-guided surgery strategy will contribute significantly to every clinical phase of prostate cancer evaluation, the assessment of targeted anti-RAGE treatment, and the efficacy of surgical intervention. Moreover, we postulate that RAGE-targeted imaging strategy could provide selective prediction of the success of novel anti-RAGE therapies and enable early determination of responders and non-responders to anti-RAGE interventions.
I am currently developing a microfluidic device to detect serum biomarkers indicative of human papillomavirus (HPV)-related oropharyngeal cancer (OPC). The device incorporates a photonic crystal platform whose special structure and composition enhance the fluorescence from the detection molecules, resulting in a stronger signal than that from traditional platforms. Unlike current detection methods which require a biopsy and/or RNA sequencing, this method would be relatively short (<5 hours) and minimally invasive, as it requires only a couple drops of blood. The photonic crystal enhanced fluorescence (PCEF) also lends to a high detection sensitivity, meaning very low concentrations of biomarkers can be detected. The hope is to use this device to detect cancer biomarkers from serum at earlier stages, when treatments have higher efficacy but the biomarker concentration is lower and more difficult to detect using traditional methods.
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.
Nervous system cells use a large variety of chemicals in order to communicate and coordinate for complex processes. One class of chemicals, known as neuropeptides, are composed of a chain of smaller units called amino acids. These amino acids have an interesting characteristic known as chirality, a concept where each of these amino acids have a mirror image that is in every other way identical to them, not unlike left and right hands. The left-handed versions are known as L-amino acids, while the right-handed versions are known as D-amino acids. L-amino acids are chosen by biology to form these neuropeptides during their initial production, a process called translation. While translation uses only L-amino acids, further modifications can be made after this process, including conversion of one these amino acids into a D-amino acids. For example, a peptide of four amino acids (LLLL) can be converted into a peptide containing one D-amino acid (LDLL for example). This has a functional consequence, such that in many cases, the neuropeptide with the D-amino acid is biologically active with the neuropeptide with only L-amino acids is not. Because these amino acids identical in every way except that they are mirror images, this modification can be very difficult to detect; the consequence of this is that it is not yet recognized as a widespread phenomenon. Thus, when pharmaceutical companies spend time and resources developing drugs to target the biological activities of neuropeptides, they synthetically prepare the peptide using only L-amino acids. If D-amino acids do exist in neuropeptides, there is a chance that some studies are wasted efforts and missing out on potential therapeutics for nervous system diseases.
To address the difficulty in detecting D-amino acids in neuropeptides, I have been working on a method that we call a D-amino acid-containing neuropeptide discovery funnel. This funnel can work in a complex peptide mixture; the technology and method are being developed using the nervous system of a mollusk, Aplysia californica. This is a good model for studying these peptides because its peptides are rather well-characterized and two D-amino acid-containing neuropeptides have already been identified in this organism. There are three steps in the discovery funnel. The first step screens for peptides potentially containing D-amino acids by their ability to resist degradation by specific enzymes (D-amino acid-containing neuropeptides are difficult to degrade). In the second step, the chirality of each amino acid is investigated using a specific chemical tag than can help differentiate the two, after breaking the neuropeptide down into its component amino acids. Finally, these peptides are synthetically prepared with the D-amino acid at the suspected position and tested to see if this is the bioactive form. The hope is to investigate other model nervous systems, like rodent nervous systems, to establish that this is a more widespread phenomenon than currently believed. This can help shape future pharmaceutical studies in nervous system disorders.
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.
Broadly speaking, my research focuses on risk and resilience factors related to health of families and children/young adults in varying contexts. We are working on several projects toward this end. As a part of the UP AMIGOS project, we are looking at the metabolic consequences of stressors and depression in young adults in Mexico with a particular interest in insulin sensitivity related outcomes. Under the umbrella of the STRONG KIDS project, we are looking at how pediatricians may impact early childhood physical activity through what they say to parents about physical activity at well-child visits. Additionally, we are working with the Division of Specialized Care for Children in Chicago to analyze their data from the state of Illinois on families with children that have special health care needs. I am also helping with an initiative on campus to bring together resources to help researches with projects related to immigrant health and am working on bringing together census data for a policy report to help when sampling for such studies.
Finally, my dissertation work is on health in the family child care context. Family child care, care that takes place in a child care provider's own home, is an understudied area in the literature. What little literature does exist suggests that child care providers may have worse health outcomes even than sociodemographically matched samples. We hope to add to the literature by doing the first in-depth study on family child care provider health with the broader goal being to inform the creation of an intervention that can be used by child care resource and referral offices across the state.
Attention deficit-hyperactivity disorder (ADHD) is a relatively common behavioral disorder with childhood onset characterized by hyperactivity, inattention and impulsivity. It is highly heritable (broad sense heritability estimates are approximately 75%). However, the specific genes and neurobiological risk factors remain a mystery. Part of the reason is that few suitable animal models have been developed. The goal of my doctoral dissertation is to evaluate a line of mice selectively bred for increased locomotor activity in their home cages for face and predictive validity as an animal model for ADHD. The two lines of mice have been maintained for over 17 generations. One line, referred to as High-Active, is subjected to within family selection each generation for increased total distance traveled in the home cage on days 5 and 6 of a six day test. Video tracking is used to precisely measure horizontal distance traveled continuously in the home cage of 6 days. The other line, referred to as Unselected Control, is randomly bred (avoiding sibling mating) each generation. My initial dissertation chapters determined that hyperactivity in our High-Active line is ameliorated by administration of therapeutic doses of d-amphetamine, while the same dose increased activity in the Control line. Moreover, I tested face validity of this potential ADHD model by determining that High-Active mice display features of motor impulsivity using the operant Go/No-go task, as compared to Controls. Importantly, the same low dose which alleviated hyperactivity was also shown to alleviate impulsivity in males and females, and in adolescence and adulthood, providing substantial evidence for the face and predictive validity of this novel ADHD model. Moreover, High-Active mice also demonstrate inattention as evidenced by poor spontaneous alternation performance in the Y-maze, and impaired cerebellar functioning as evidenced by the rotarod task. Future goals are centered on identifying novel gene pathways which mediate hyperactivity.
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 study utilizes the idea of embodiment to examine the social processes that “undocumented” Latin American immigrants undergo and how these social processes affect their health. Embodiment refers to how our bodies and minds literally incorporate, from conception to death, the material and social world in which we live (Krieger, 2001b). The study uses a critical intersectional lens and an adapted grounded theory approach to analyze 31 original qualitative in-depth interviews with nationally diverse “undocumented” Latin American immigrants from the Washington, DC metropolitan area in order to create a theoretical framework that addresses: (1) how “undocumented” Latin American immigrants experience structural violence and inequality through various pathways, such as labor exploitation, detention and deportation, gender based violence, racialized nativism, discrimination and othering, fragmentation of social ties, and internalized suffering, which results in differential exposure and susceptibility; (2) how “undocumented” Latino/a immigrants respond to and contend with inequality; and (3) how structural violence and inequality become deleterious physical and mental health outcomes through multilevel pathways of embodiment.
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.
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.
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 mechanisms by which exercise can facilitate extinction of conditioned place preference (CPP) for cocaine in C57BL/6J mice.
Exercise has been shown to weaken drug-to-context associations in the CPP paradigm in mice. As such, exercise could be a potential means to reduce the emotional reactions to environmental stimuli that result in drug craving and predispose vulnerable individuals towards relapse. While the mechanisms by which exercise can reduce CPP for cocaine are currently unknown, some evidence suggests that exercise-induced hippocampal neurogenesis might play a role. I am using a novel transgenic mouse model (nestin-HSV-thymidine kinase) and systemic administration of valganciclovir to selectively reduce neurogenesis. My goal is to determine whether exercise-induced hippocampal neurogenesis is required for exercise to weaken CPP for cocaine. To confirm ablation of hippocampal neurogenesis in the valganciclovir-receiving transgenic mice, I am staining for BrdU, NeuN, and S100β in the dentate gyrus. I am also working with a Chemistry lab (the Sweedler group) conducting MALDI-TOF MS to identify novel and known neuropeptides differentially expressed in sedentary versus runner animals in the amygdala and hippocampus in mice that have been re-exposed to a drug-associated context. Ultimately, I hope to better understand mechanisms by which exercise can weaken drug-to-context associations and to advance our understanding of the role of hippocampal neurogenesis in exercise-induced reduction of CPP.
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.
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.
Yersinia pestis is the causative agent of bubonic, septicemic, and pneumonic plague. This pathogen subverts the immune response of its host by several different mechanisms, however some hosts resist infection, and this resistance has been found to be heritable. Our lab has focused on inbred strains of mice and found several that show resistance in a pgm- plague model. By breeding the resistant mice with mice that are susceptible and then screening the offspring for novel crossovers I create new lines which are then tested for either maintenance or loss of resistance. In this way we have been attempting to determine which genes may play a role in conferring resistance to plague. We have mainly been following two separate loci, one on chromosome 1 of mice of the 129 background, and a second on chromosome 17 in Balb/cJ mice. In order to look at the molecular basis of resistance we have been isolating different cell types and testing the ability of each to either control bacterial growth or kill Y. pestis.
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 main research interest is the interface between the ecology and epidemiology of vector-borne disease. Specifically, my dissertation focuses on the eco-epidemiology of Chagas disease in Panama. Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is transmitted by several species of blood-feeding insect in the subfamily Triatominae (Hemiptera: Reduviidae). Many of these species are considered sylvatic, meaning they live the majority of their lifecycle outside human contact, and these species are often considered only incidental or spillover vectors of disease. I am interested in better understanding the epidemiological risk factors associated with Chagas disease transmission as well as the potential impact of sylvatic species of triatomine vectors to household transmission across an urban-to-rural human land-use gradient in Panama Province, Panama.
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.
Childhood obesity is a nutrition-related disease with multiple underlying etiologies. The gut microbiota is thought to be a contributor in the development of obesity by fermentation of non-digestible polysaccharides to short chain fatty acids (SCFA), which increases host capacity for energy harvest and storage. Several genes encoding SCFA receptors and transporters, as well as other host responders to gut microbiota have been described. However, the collective impact of common genetic variations (single nucleotide polymorphisms [SNP]) in these genes on obesity phenotypes has yet to be examined in humans. Our hypothesis is that genetic variation in SCFA recognition pathways are related to excess weight gain and microbial distinct profiles are associated with overweight and obesity in children. This proposal will also use a unique approach in studying the relationship between gut microbiota and obesity by evaluating both traditional anthropometric measurements and percent body fat measured by dual energy x-ray absorptiometry (DXA).
This approach here may reveal novel biomarkers for obesity susceptibility at an early age. Analysis of genetic factors will provide needed information for the development of early detection methods including genetic screening for obesity risk. Additionally, an understanding of key microbial players and the metabolites they produce in the gut of children with normal or high BMI and percent body fat will pave the way for therapeutics designed to achieve and maintain optimal gut health.
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.
My research interests lie at the intersection of nutrition and cognitive neuroscience, and focus on the neural and neuropsychological effects of nutrition. My work is motivated by the question of how dietary nutrient intake may impact cognitive processes and the underlying neural structures in humans. Ultimately, I’d like to understand how we could best utilize diet to both prevent deterioration of cognitive function associated with brain aging or dysfunction as well as enhance cognitive function in healthy individuals.