Ischemic preconditioning (IPC) is a phenomenon in which a brief ischemic event confers protection against subsequent prolonged ischemia, such as stroke. Understanding the mechanisms underlying this endogenous neuroprotective response could lead to advances in stroke therapeutics. Most experimental rodent models of stroke focus on injury to grey matter. However, injury to the white matter (WM) is a significant component of ischemic stroke in human patients and is poorly understood. Our laboratory has shown that microglial innate immune signaling is required for WM IPC-induced protection. The nodes of Ranvier (NoR) are critical WM structures that control conductance and action potential propagation along axons. Recent studies have shown elongation of the NoR in the context of WM injury and disease. The mouse optic nerve (MON) is a fully myelinated central nervous system WM tract. We expose MONs to a brief in vivo ischemic event to induce IPC. Seventy-two hours later, we isolate MONs and expose them to ex vivo oxygen-glucose deprivation (OGD) to mimic stroke. Using MONs from mice that underwent pharmacologic depletion of microglia followed by in vivo IPC and then ex vivo OGD, I performed immunohistochemistry with Nav1.6 and Caspr antibodies to label the NoR and image them with a confocal microscope. NoR size, diameter, and length are quantified with ImageJ in conjunction with an in-house MATLAB script. I hypothesize that IPC will protect and conserve structural parameters of the NoR from OGD-induced injury and that this protection will be eliminated by microglial depletion. Our preliminary data show feasibility of this project (i.e., all the methods to carry out this work are in place) and we can generate precise and reproducible measurements of the NoR in MONs. Findings from this project will provide a better understanding of the mechanisms by which microglia mediate IPC-induced axonal protection in WM.
 

Previous studies show that the high prevalence of body image concern and disordered eating among Western women precipitates from the promotion of an unrealistically thin body ideal. Exposure to thin-idealized images on social media has been found to increase body dissatisfaction and perpetuate internalization of anti-fat attitudes. The present research examined whether implicit anti-fat attitudes can be internalized without ever being visually exposed to body shapes. Preliminary results from a sample of blind women (N = 18) in Israel revealed that implicit anti-fat attitudes in blind females are comparable to those of sighted controls. The purpose of this study was to expand on these original findings by administering a novel auditory weight-bias Implicit Association Test (IAT) to larger samples of blind women (N = 30) and sighted controls (N = 30) across the United States. Participants completed an auditory IAT in which they paired words describing thin bodies and words describing overweight bodies with either negative or positive words in congruent and incongruent blocks. Afterwards, they answered self-report questionnaires to evaluate body dissatisfaction, pursuit of the thin ideal, and perceived pressure from family, friends, significant others, and the media to attain a thin body. In our analysis, I helped compare reaction times of blind and sighted female participants. Implicit anti-fat bias was reflected as slower reaction times when words describing overweight bodies were paired with positive words compared to when they were paired with negative words. If results of the present study replicate the preliminary results, we will develop stronger evidence towards the existence of non-visual influences that contribute to thin-ideal internalization. Additionally, these results would demonstrate that internalization of the thin-ideal can occur without any visual exposure to body shapes.These results may shed light on sociocultural factors that should be considered in evaluating disordered eating risk among blind women.

In the United States, caregivers carry a higher level of physical and emotional stress than non-caregivers. According to the National Alliance for Caregiving, over 60% of caregivers consider their caregiving situations to be moderate to highly stressful. In response to the multifaceted needs of family caregivers, a team of health researchers and engineers initiated a research project called COCO ("Care for Caregivers Online"). COCO’s goal is to design and implement innovative methods to support caregivers emotionally. We have implemented a system with two platforms connecting family caregivers with healthcare providers: a web app with a conversational agent (“chatbot”) for caregivers and a provider platform using artificially intelligent (AI) technologies for healthcare providers to provide effective and efficient support through the mobile app. We conducted a pre-post study with forty caregivers who chatted with COCO through the system. The initial result shows that COCO significantly reduces caregivers’ negative feelings including guilt, sadness, and fatigue. We are expecting more positive results after deploying the mobile application with the chatbot embedded. Additionally, I, along with other reasearchers, conducted research on chatbot’s ability of emotion detection. We collected caregivers’ emotional state data through a two-week diary study and I personally preprocessed and analyzed the data.  We then used these data to develop a natural language understanding (NLU) model. In simplicity, we incorporated the ability of commonsense into the chatbot, achieving better results in emotional state inference and grounding response recommendation. I am currently leading a digital human project, creating a virtual human profile for COCO to ahieve better user experience. The integrated care approach COCO takes with AI-enhanced empathetic and therapeutic dialogs has the potential to address the critical needs of millions of family caregivers in an accessible, scalable, and cost-effective way.

Microfluidics is the technology of systems in which microscale channels are used to manipulate small quantities of fluids (microliter to picoliter or less). Open microfluidics provides a platform to control the movement of microscale volumes of liquid in open space, making every position more accessible than conventional closed microfluidics. In many applications–including cell culture, chemical synthesis, and high throughput screening–merging droplets is essential for the experimental workflow. For example, merging droplets containing reagents can initiate a chemical reaction, or adding a drug to a cell culture can stimulate cells. In conventional closed droplet-based microfluidics, merging techniques often rely on external components such as merging by electrofusion using electrodes. In other cases, like merging using hydrophilic strips in a channel, the merging method is built into the device and the location of merging must be determined in advance. Therefore, the ability to easily initiate droplet merging in an open microfluidic system would be beneficial to researchers and offer flexibility in experimental design and applications. In this study, I developed an easily accessible droplet fusion technique with the prick of a needle at the liquid interface; my method fuses multiple droplets simultaneously (2-15 droplets). Importantly, this fusion method can be used on-demand at any point in the open microfluidic device and does not require external equipment nor features built into the device. This presentation characterizes the experimental parameters required for successful and controlled droplet fusion and explores the physics behind this phenomenon.

Cholera is a diarrheal disease caused by intestinal bacterium Vibrio cholerae. This enteric disease affects millions of patients each year and it is primarily caused by contaminated food or water. V. cholerae (Vc) infected patients can be asymptomatic or develop severe acute diarrheal symptoms. We previously used metagenomic sequencing to characterize the gut microbiota of household members of patients with cholera and found that gut microbe Rothia mucilaginosa (Rm) is present in higher relative abundance among patients with Vc compared to uninfected individuals. Here we aim to investigate how this gut bacteria interact with Vc and/or impact Vc biofilm formation. To analyze Vc biofilm, we co-cultured Rm with Vc at 37C for six hours and quantified biofilm formation using a microtiter dish assay with crystal violet staining. We first tested the biofilm formation of Vc and Rm in monocultures as controls and then we performed co-culture assays with different ratios including 1:1, 1:10, and 2:1 Vc to Rm. Additionally, heat killed and spent-cell supernatant conditions of Rm were also used to determine the interaction between Vc and Rm. Preliminary results from our biofilm assays suggests that Rothia mucilaginosa promotes increased biofilm formation of Vc. In conclusion, we found that native members of the gut microbiome can induce formation of biofilms and this interaction between gut microbe and pathogen has the potential to affect the disease outcomes.

 Mutations are the main source of diversity due to the random changes in genetic sequence. Mutation rate can be influenced by genetic modifiers, DNA damage, and the environment. Mutator alleles, which cause high mutation rates, are less known about how often they arise in the natural populations and how they interact with other genomic changes, such as recombination and introgression. Using the natural isolates of the 1,011 strains of the budding yeast Saccharomyces cerevisiae, we examined the relative frequencies of different types of mutation calculated from natural polymorphisms, i.e. mutation spectrum, to determine potential historical impacts of S. cerevisiae mutation rate modifiers that affect certain mutation rates disproportionately. From the mutation spectra analysis, we observed African Beer strains are outliers and some French Dairy strains show a mutation spectra more similar to African beer strains than the rest of the strains. Our initial analysis of the two groups of strains suggests potential mutator allele introgression from the African Beer to some of the French dairy strains. We set out to examine de novo mutation spectra from African beer, French dairy strains with and without African beer Introgression. The natural strains have a variety of ploidies so we repurposed our existing mutation accumulation pipeline with haploid strains. Using CAN1 as a reporter gene, we deleted the endogenous locus using CRISPR-Cas9 and inserted a sensitive copy to measure the mutation spectra in these strains to test the hypothesis. We expect to find the introgressed French dairy strains’ mutation spectra resemble that from African beer strains if our prediction is correct. Ultimately, our results will shed light on how mutators behave in natural populations of budding yeast and how they contribute to evolution.

Airline flight schedules face various kinds of stochastic disruptions, such as inclement weather, that cause flight delays. These delays then propagate and disrupt the regular operations of subsequent downstream flights. These propagated delays can be extremely costly to airlines, so it is beneficial to reduce disruptions to subsequent flights. To minimize these disruptions, we consider the stochastic nature of these disturbances when creating aircraft routes that reduce delay propagation and are manageable once disrupted. In this study, we develop and compare three stochastic optimization models to optimize aircraft routing: (i) robust optimization, (ii) chance-constrained programming, and (iii) stochastic programming. To solve these models, we modify an efficient approach for solving vehicle routing problems with time windows and capacity constraints known as the Vehicle Routing and Scheduling Algorithm (VeRSA) for these three models. VeRSA is the integration of a heuristic with an exact method to quickly find a feasible solution while also providing an optimality gap and a guaranteed optimal solution. A benefit of VeRSA is the ability to devise a flexible index that can accommodate different objectives for various forms of uncertainty. VeRSA can also modify the feasibility routine that accommodates the complex aircraft maintenance constraints, which is a challenge in the mathematical programming approach. Using various delay scenarios, we compare the performance of the solutions from our three stochastic optimization models and discuss insights regarding their performance differences. Preliminary results using the base model and a small example have been solved in Gurobi while future results using real data from airlines in VeRSA are pending.

The mesolimbic dopamine system mediates various behavioral functions, including motivation and reward association. Midbrain dopamine neurons of the ventral tegmental area (VTA) send projections to the nucleus accumbens (NAc), forming the mesolimbic pathway. It has been hypothesized that two subregions of the NAc, core and shell, are differentially involved in motivation and reward association. Previous studies identified distinct groups of dopamine neurons with synaptic projections to either the core or shell. The goal of this project is to establish the functional roles of core- and shell-projecting VTA neurons in motivated behavior. More specifically, we investigate whether either subpopulation is necessary or sufficient to reinstate an extinguished goal-directed behavior. The optogenetic approach allows for millisecond-precise gain or loss of function in distinct neural circuits. We use transgenic mice engineered to express Cre-recombinase in either core- or shell-projecting dopamine neurons. Cre-dependent targeting confers cell-type specificity while local intracranial injection of light-sensitive opsins via viral vector provides anatomical specificity. After surgical manipulations, mice undergo a conditioning task with separate acquisition, extinction, and reinstatement phases to measure the rate of food reward retrieval. Operant conditioning paradigms provide the ability to dissect how cues, contexts, and instrumental responses influence goal-directed behavior. During acquisition, mice are trained for six days of lever pressing for food reward paired with an audiovisual cue. In the extinction phase, no reward or cue is delivered. During reinstatement, lever pressing is followed by laser stimulation and cue presentation. We hypothesize that VTA-core-projecting and VTA-shell-projecting neurons differentially regulate cued reinstatement behavior. Our project will provide insight into the functional organization of the mesolimbic pathway and its role in motivated behavior. Collectively, these studies will establish the anatomical basis of dissociable aspects of motivation, extinction, and reinstatement of reward-seeking behaviors, which are implicated in substance abuse and obsessive-compulsive disorders.