Texas Digital Library
UT Southwestern Medical Center Institutional Repository (University of Texas)Not a member yet
10274 research outputs found
Sort by
Design, Development, and Interrogation of Salmonella Typimurium Minimal Effector Networks During Infection
No full textPages 136-174 are misnumbered as pages 137-175.Salmonella enterica serovar Typhimurium utilize a Type Three Section System (T3SS) to deliver virulent "effector" proteins directly into the host cell cytoplasm. Some of these effectors have been biochemically characterized, but many of them can be deleted individually with little reduction in bacterial pathogenicity. Thus, determining the interrelationship between effector gene networks, host substrates, and pathogen virulence has been challenging. Using targeted mutagenesis and phenotypically informed genome reassembly, we engineered a minimal SPI-2 T3SS effector gene network that supports Salmonella enterica serovar Typhimurium (STm) intracellular replication in vitro and disease pathogenesis in a murine model of Typhoid-fever. Genetic analysis of the host immune response to this minimal effector gene network reveals a sophisticated interplay between host immunity and bacterial disease progression. Further analysis reveals the specific immune responses during infection at a dynamically novel resolution. The interplay between SPI-2 effector proteins and immune cell targets reveals an advanced complexity of host-pathogen interactions, illustrating the cooperation necessary to drive tissue tropism during bacterial pathogenesis and a powerful tool for interrogating effector functions in vivo which has further implications for Salmonella pathogenesis in the host
Investigating the Role of Standing Blood Pressure Measurement and the Association Between High-Density Lipoprotein and Skeletal Muscle Mitochondrial Function in Pre-Hypertensive Humans
No full textCardiovascular disease (CVD) is the leading cause of death in the United States. Importantly, two main driving forces behind developing CVD is the presence of hypertension (HTN) and dyslipidemia. Despite this, there are critical knowledge gaps related to 1) obtaining an accurate clinical assessment of blood pressure (BP), and 2) the mechanisms by which dyslipidemia evoke enhanced cardiometabolic disease risk. Specifically, this dissertation aimed to 1) investigate the role of standing office BP measurement in facilitating HTN diagnosis, and 2) characterize the associations between high-density lipoprotein (HDL) and skeletal muscle mitochondrial function. Herein, we are the first to observe that standing BP measurements are highly accurate in detecting HTN when compared to seated BP. These findings demonstrate standing BP as a novel tool to enhance the accuracy of office BP assessment. Likewise, we are the first to demonstrate higher levels of HDL cholesterol and apolipoprotein A-I are independently associated with enhanced skeletal muscle mitochondrial function in humans. These findings are important because disruptions in skeletal muscle metabolism have been associated with exercise intolerance. In conclusion, our studies have direct implications on the screening of HTN and highlight the utility of measuring BP in both the seated and standing positions. Moreover, we provide evidence for future research aimed at establishing the causal relationship between HDL structure and function with exercise endurance in humans. These studies aimed at addressing two critical gaps in knowledge, and upon completion, have further elucidated more optimal methods of assessing office BP and provided an enhanced understanding of the relationship between dyslipidemia and cardiometabolic disorders
TMEM30a Facilitates Murine Norovirus Entry and Persistent Enteric Infection
No full textNorovirus, the leading cause of gastroenteritis worldwide, is a non-enveloped virus whose tropism is determined in part by the expression patterns of entry receptors. However, the contribution of cellular lipids to viral entry is not well understood. Here, we determined that the asymmetrical distribution of lipids within membrane bilayers is required for murine norovirus (MNV) replication. Specifically, TMEM30a, an essential subunit of lipid flippases, is required for MNV replication in vitro. Disruption of TMEM30a in mouse intestinal epithelial cells prevents persistent, enteric infection by MNV in vivo. Mechanistically, TMEM30a facilitates MNV binding and entry. Exoplasmic phosphatidylserine (PS), a typical marker of dying cells, does not inhibit MNV infection. Exoplasmic phosphatidylethanolamine (PE) rather than PS is associated with viral inhibition. Our data provides a new role for PE in membrane homeostasis and highlights the need for lipid asymmetry in promoting non-enveloped viral infection in vitro and norovirus persistence in vivo
ERK1/2 Activation in Macrophages Is Necessary for Efficient Leishmania amazonensis Internalization and Pathogenesis
Full text linkLeishmania is an obligate intracellular protozoan parasite that binds to numerous host cell receptors to cause phagocytic cell uptake, resulting in visceral or cutaneous leishmaniasis. When Leishmania engages receptors during the internalization process, it activates a number of signaling pathways. The host machinery that mediates Leishmania uptake, on the other hand, remains unexplored. In this thesis, we uncovered new mechanisms regulating Leishmania internalization and pathogenesis. Using small-molecule inhibitors of Mitogen-activated protein kinases/Extracellular signal regulated kinases (MAPK/ERK) and primary macrophages lacking Arg/Abl and Spleen Tyrosine Kinase (SYK), We show that ERK1/2 and SYK regulate macrophage internalization of Leishmania amazonensis and phagocytosis of beads. Consistent with these results, we hypothesized MEK1/2 or ERK1/2 inhibition in macrophages leads to production of large F-actin-rich phagocytic cups, showcasing a defective phagocytic process. Interestingly, ERK1/2's role in uptake is relatively specific to Leishmania, as beads mildly activate ERK1/2, while MAPK inhibitors only slightly diminish internalization of beads. Furthermore, SYK and Arg/Abl family kinases are essential, as they mediate the ERK1/2 kinase activity required for effective internalization. Finally, entospletinib, a SYK inhibitor, as well as trametinib, a MEK1/2 inhibitor, substantially decrease disease severity and parasite load in Leishmania-infected mice. Our studies show that SYK and MAPK/ERK signaling kinases are required for maximum Leishmania infection and effective phagocytosis, suggesting these pathways as possible treatment targets for leishmaniasis
Structural Investigations of Porcupine and Dispatched-1 in Wnt and Hedgehog Morphogen Biogenesis
Full text linkHere, I present the cryo-EM studies in two key developmental signaling pathways, Hedgehog (HH) and Wnt signaling pathways. HH signaling is vital for metazoan development, and its ligand is secreted by a cell surface protein named Dispatched-1 (DISP1). I report the cryo-EM structure of the DISP1 in complex with dual lipid-modified HH ligand, suggesting how DISP1 engages with HH ligand. DISP1 contains 12 transmembrane helices and two extracellular domains (ECDs) in an open state, unlike its structural homologues PTCH1 and NPC1, whose extracellular/luminal domains adopt a closed state.
Wnt signaling is essential for embryonic development and adult tissue homeostasis, and aberrant Wnt signaling is frequently associated with cancer. Palmitoleoylation on the hairpin 2 motif by the endoplasmic reticulum-resident membrane-bound O-acyltransferase Porcupine (PORCN) is indispensable for Wnt binding to its receptor Frizzled, which triggers signaling. I report four cryo-EM structures of human PORCN: the complex with its substrate palmitoleoyl-coenzyme A, the complex with the PORCN inhibitor LGK974, the ternary complex with LGK974 and WNT3A hairpin 2 (WNT3Ap), and the complex with its product - a synthetic palmitoleoylated WNT3Ap analogue. These structures reveal that hairpin 2 of WNT3A inserts into PORCN from the lumenal side, and the palmitoleoyl-CoA accesses the enzyme from the cytosolic side. The catalytic histidine triggers the transfer of the unsaturated palmitoleoyl group to the target serine on the Wnt hairpin 2, facilitated by the proximity of the two substrates. The inhibitor LGK974 occupies the palmitoleoyl-CoA binding site to prevent the reaction.
In summary, my studies provide insights into the structure and function of human DISP1, which is involved in HH signaling, and PORCN, which plays a crucial role in Wnt signaling. These findings shed light on the mechanism of morphogen biogenesis in Hedgehog and Wnt signaling pathways and could pave the way for the development of new therapeutics to target these pathways
Detection and Prevention of Overinflation of the Tracheal Tube Cuff During Surgery at a Tertiary Care Hospital
Full text linkThe 63rd Annual Medical Student Research Forum at UT Southwestern Medical Center (Tuesday, January 28, 2025; 3-6 p.m.; D1.700 Lecture Hall)BACKGROUND: Excessive pressures (>30 cm H2O) in the cuff of an endotracheal tube can restrict blood flow and damage the tracheal mucosa, leading to short-term adverse events such as sore throat, hoarseness, and bloody cough, as well as long-term complications, including tracheal stenosis, ulceration, necrosis, and rupture [1]. Clinical studies indicate that tracheal cuff pressures are frequently outside the recommended range (20-30 cm H2O), with reported rates of deviation from this range in 60-80% of cases [2].
HYPOTHESIS: This study aims to decrease tracheal cuff overinflation in non-cardiac surgery patients under general anesthesia at Parkland Hospital while simultaneously enhancing anesthesia providers' knowledge of accurate cuff pressure measurement and associated risks.
MATERIALS AND METHODS: This prospective study was conducted in three phases using data collected in the operating rooms of Parkland hospital. In Phase 1, baseline tracheal cuff pressure data were collected from 100 intubated patients. Phase 2 consisted of educational sessions given to anesthesia providers at Parkland that presented our baseline pressure readings and then demonstrated optimal cuff pressure measurement techniques. In phase 3, manometers were placed in the operating rooms and tracheal cuff pressures were measured in a subsequent sample of 63 patients to assess the intervention's impact 4-16 weeks after its presentation.
RESULTS: The incidence of over-inflation decreased by approximately 50%, from 90% pre-intervention to 44% post-intervention (P<0.0001). The mean cuff pressure decreased from 76.8 Cm H2O to 37.6 Cm H2O (p<.0001). The variability in cuff pressures also decreased after intervention (standard deviation 45.3 Cm H2O and 23.5 Cm H2O pre- and post-intervention, respectively). A manometer was used in 59% of the cases after the intervention, compared to 1% of the cases before the presentation.
CONCLUSION: Our intervention successfully reduced the incidence of tracheal cuff overinflation in patients undergoing general anesthesia at Parkland Hospital.Southwestern Medical Foundatio
Single Molecule-Based Computer Vision Analysis of Cortical Actin-Plasma Membrane Protein Interplay
Full text linkThe file named "NGO-PRIMARY-2025.pdf" is the primary dissertation file. The file named "1745621082149-Supplementary Video.zip" is a zipped file folder that contains 10 movie files (MP4 format), and a description of each video is included in Appendix B of the primary file (pages 148-149).The spatiotemporal organization of plasma membrane proteins is regulated by cortical actin, yet quantitatively resolving the interplay between plasma membrane proteins and the cortical actin dynamics remains challenging. To address this, I developed a multiscale imaging and quantitative computer vision tool that integrate Single-Molecule Imaging and Fluorescence Speckle Microscopy (SMI-FSM) to quantitatively analyze how cortical actin dynamics can influence plasma membrane organization in live endothelial cells. Application of this tool, complemented with other image-based analysis - including conditional colocalization analysis, showed that the dynamic organization of cell surface receptor CD36 varies across different membrane subregions and is modulated by cortical actin dynamics. Cortical actin dynamics were predictive of differences in plasma membrane mobility near cell edges versus closer to the cell center. In addition, we found that global changes in actin properties caused by perturbation were not necessarily reflected in the cortical actin properties near plasma membrane proteins, and that the changes in plasma membrane protein properties upon perturbation varied based on the local cortical actin environment. Because CD36 has short intracellular domains and no known molecular link to cortical actin, we also identified the β1-integrin subunit and several tetraspanins - CD9, CD81, and CD151, as part of the previously unknown link between CD36 and cortical actin. We found that CD36 is recruited into complexes/nanodomains containing these proteins. The point mutation G12V altered CD36's interactions with integrins and tetraspanins, changing its membrane organization, weakening its relationship to actin dynamics, and abolishing CD36 downstream signaling in response to thrombospondin-1. These findings suggest that integrins and tetraspanins may also mediate the coupling between many other plasma membrane constituents and cortical actin. Here, we highlight the strength of imaging-based studies in that they reveal subcellular spatial information that is difficult to obtain otherwise. Given the widespread use of single molecular imaging as a method to study the spatiotemporal organization of plasma membrane proteins and the versatility of SMI-FSM, we expect it to be widely applicable to enable future investigation of the influence of cortical actin architecture and dynamics on different plasma membrane proteins, especially in the context of actin-dependent cellular processes
Anorectal Malformations at Children's Health: Understanding Our Patient Population, Patterns of Disease, and Surgical Outcomes Over a 10-Year Period
Full text linkPROBLEM: Children with anorectal malformations require complex procedures and often require long-term bowel management and clinical care for optimal quality of life. The demographics and outcomes of patients with anorectal malformations at Children's Health are unknown.
METHODS: The electronic medical record at Children's Health was searched for ICD-9, ICD-10, and CPT(r) codes corresponding to anorectal malformations between 2009 and 2019. Patients who underwent definitive operation prior to Summer 2009 or at another hospital were excluded. Patient demographics, imaging studies, medical history, operative procedures, post-operative complications, and follow-up data were collected and analyzed. IRB approval was attained (STU-2020-0089).
RESULTS: 178 patients met inclusion criteria. A definitive anoplasty procedure was performed in 176 patients (55% female), with most (70%) undergoing posterior sagittal anorectoplasty. Patients identified as Hispanic/Latino (n=93, 53%), white (45, 26%), black or African American (22, 12%), and Asian (7, 4%). English (n=122) and Spanish (n=50) were the most common home languages. 144 patients (82%) had a "low" malformation. 117 patients (66%) underwent a staged operation. VACTeRL association was identified in 68 patients (39%). The most common type of malformation was perineal fistula followed by rectovestibular and recto-prostatic urethral fistula in girls and boys, respectively. Out of the 170 patients who underwent a definitive operation and had at least one follow-up visit post-operatively, 18 (11%) had post-operative stricture requiring operative dilation or revision. In our multi-variate regression model, the presence of a cardiac anomaly confers a 4-fold risk of post-operative stricture while each month older at the time of anoplasty reduces the risk by almost 10%.
CONCLUSION: We created a data registry for patients with anorectal malformations at Children's Health. The majority of our patients are Hispanic, female, and have an associated anomaly. Anal stricture occurs in about 10% of patients, and children with congenital heart disease may benefit from delay in repair to reduce their increased risk of post-operative stricture. The development of a multidisciplinary program to manage and follow patients long-term is anticipated to improve surgical outcomes and patient retention
Reframing indigenous health through genomic data sovereignty and equity
Full text link[Note: The slides are not available from this event.] Tuesday, May 13, 2025; noon to 1 p.m. (Central Time); via Zoom. "Reframing Indigenous Health Through Genomic Data Sovereignty and Equity". Krystal S. Tsosie, Ph.D., M.P.H., Assistant Professor in the School of Life Sciences and Associate Director of the Biodiversity Knowledge Integration Center at Arizona State University.[Note: The slides are not available from this event.] The next discoveries in genomic medicine are likely to be rare or uncovered variation from populations absent in current datasets. Indigenous peoples -- who are concerned with data sharing, privacy, broad consent, and group risks of re-identification that are unlikely to be resolved by open data -- encounter many dilemmas. How can Indigenous peoples benefit from precision health though they derive lower clinical utility and have severe structural barriers to care? How can they contribute to genomic datasets, if they wanted to, and not be subject to data co-optation and commercialization in innovation pathways that are inaccessible to Indigenous peoples? Merely increasing inclusion of Indigenous peoples in genomic datasets is not going to solve the health inequity problem without drastic shifts in benefit- and data-decision equity via Indigenous-led biobanking and machine learning approaches. The era of community-based participatory research has transitioned to Tribally based research in genomics and health.UT Southwestern--Program in Ethic
Continuing Innovation in Evaluation of Surgical Technical Skill: Tailoring OSATS for Bedside Robotic Tasks
No full textThe general metadata -- e.g., title, author, abstract, subject headings, etc. -- is publicly available, but access to the submitted files is restricted to UT Southwestern campus access and/or authorized UT Southwestern users.BACKGROUND: Strong technical performance is a metric that every surgeon and every patient should be interested in. Technical performance has been linked to lower complications rates. How we best measure technical performance is a hotly contested issue and rife for continued innovation. As a pilot project we seek to develop a rubric to assess the technical performance of everyone in the operating room team so that we can bolster better patient outcomes, safety, and education.
OBJECTIVE: Develop objective metrics to assess bedside assistants in robotic surgery.
METHODS: Generate a specialized rubric for scoring technical performance during robotic docking using a comparison of novice and expert performance observation and analysis in both the simulation center, and eventually live operating room theaters. Furthermore, to determine the value of incorporating Intuitive Surgical(r) bedside training programs into robotic curriculums.
OUTCOMES: A validated tool for applications such as robotics curriculum development, student or candidate assessment, and measurement and further research of surgical outcomes related to objective metrics of technical performance of the bedside assistant during robotic assisted surgical procedures