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result(s) for
"Christina Y. Cho"
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Tools to Support K–2 Students in Mathematical Argumentation
by
Bethany Lockhart
,
Jody Guarino
,
Rachael Gildea
in
Classrooms
,
Elementary Education
,
Elementary School Mathematics
2019
A yearlong professional development project investigated types of discourse and argumentation that students engage in, participation structures and routines that teachers can include to support students, and types of tasks that promote mathematical argumentation.
Journal Article
An Innovation Diffusion and Adoption Model: A Comparative Multiple Case Study of an Intensive Academic-Orientation Boot Camp Program
2017
The purpose of this multiple comparative case study was to examine why and how an intensive academic-orientation innovation was diffused and adopted at five different public research universities. The innovation under study was the Louisiana State University (LSU) Biology Intensive Orientation for Students (BIOS) program. Everett Rogers’ (2003) diffusion of innovation theory served as the theoretical framework for this study. Program documentation was collected and reviewed, an on-line survey was administered and completed by each program coordinator/director, and telephone interviews were conducted with each program coordinator/director. The study found there was relative fidelity in the adoption of BIOS and supported the presence of Rogers’ (2003) innovation attributes. A model was developed through this study to describe a successful innovation adoption process; essential elements, roles, and relationships were identified. Key findings of the study included the following: (a) need for a catalyst that the innovation addressed and impacted in a positive way; (b) a credible change agent, who was available to share knowledge about the innovation; (c) a champion, who was committed to the successful adoption of the innovation; and (d) an opinion leader, who supported the innovation adoption. The model further indicates there must be a productive and positive working relationship between the change agent and the champion, as well as an established positive working relationship between the champion and opinion leader. Discontinuation of the innovation adoption is possible if there is a change in opinion leadership or a less complex or less costly solution to the initial catalyst is discovered.
Dissertation
Engineered allostery in light-regulated LOV-Turbo enables precise spatiotemporal control of proximity labeling in living cells
2023
The incorporation of light-responsive domains into engineered proteins has enabled control of protein localization, interactions and function with light. We integrated optogenetic control into proximity labeling, a cornerstone technique for high-resolution proteomic mapping of organelles and interactomes in living cells. Through structure-guided screening and directed evolution, we installed the light-sensitive LOV domain into the proximity labeling enzyme TurboID to rapidly and reversibly control its labeling activity with low-power blue light. ‘LOV-Turbo’ works in multiple contexts and dramatically reduces background in biotin-rich environments such as neurons. We used LOV-Turbo for pulse-chase labeling to discover proteins that traffic between endoplasmic reticulum, nuclear and mitochondrial compartments under cellular stress. We also showed that instead of external light, LOV-Turbo can be activated by bioluminescence resonance energy transfer from luciferase, enabling interaction-dependent proximity labeling. Overall, LOV-Turbo increases the spatial and temporal precision of proximity labeling, expanding the scope of experimental questions that can be addressed with proximity labeling.
The light-sensitive LOV domain was engineered into the TurboID enzyme, creating ‘LOV-Turbo’. LOV-Turbo enables optogenetic control over proximity labeling, increasing the spatiotemporal precision of this technique.
Journal Article
Luciferase-LOV BRET enables versatile and specific transcriptional readout of cellular protein-protein interactions
2019
Technologies that convert transient protein-protein interactions (PPIs) into stable expression of a reporter gene are useful for genetic selections, high-throughput screening, and multiplexing with omics technologies. We previously reported SPARK (Kim et al., 2017), a transcription factor that is activated by the coincidence of blue light and a PPI. Here, we report an improved, second-generation SPARK2 that incorporates a luciferase moiety to control the light-sensitive LOV domain. SPARK2 can be temporally gated by either external light or addition of a small-molecule luciferin, which causes luciferase to open LOV via proximity-dependent BRET. Furthermore, the nested ‘AND’ gate design of SPARK2—in which both protease recruitment to the membrane-anchored transcription factor and LOV domain opening are regulated by the PPI of interest—yields a lower-background system and improved PPI specificity. We apply SPARK2 to high-throughput screening for GPCR agonists and for the detection of trans-cellular contacts, all with versatile transcriptional readout.
Journal Article
Efficacy and safety of next-generation tick transcriptome-derived direct thrombin inhibitors
by
Iyer, Janaki Krishnamoorthy
,
Hoffman, Maureane
,
Becker, Richard C.
in
631/154/309/2144
,
631/443/1338/567
,
631/45/611
2021
Despite their limitations, unfractionated heparin (UFH) and bivalirudin remain standard-of-care parenteral anticoagulants for percutaneous coronary intervention (PCI). We discovered novel direct thrombin inhibitors (DTIs) from tick salivary transcriptomes and optimised their pharmacologic activity. The most potent, ultravariegin, inhibits thrombin with a
K
i
of 4.0 pM, 445-fold better than bivalirudin. Unexpectedly, despite their greater antithrombotic effect, variegin/ultravariegin demonstrated less bleeding, achieving a 3-to-7-fold wider therapeutic index in rodent thrombosis and bleeding models. When used in combination with aspirin and ticagrelor in a porcine model, variegin/ultravariegin reduced stent thrombosis compared with antiplatelet therapy alone but achieved a 5-to-7-fold lower bleeding time than UFH/bivalirudin. Moreover, two antibodies screened from a naïve human antibody library effectively reversed the anticoagulant activity of ultravariegin, demonstrating proof-of-principle for antidote reversal. Variegin and ultravariegin are promising translational candidates for next-generation DTIs that may reduce peri-PCI bleeding in the presence of antiplatelet therapy.
Bleeding complications limits the use of effective antithrombotics therapeutics. Here, the authors developed next-generation direct thrombin inhibitors with low bleeding risks as safe peri-percutaneous coronary intervention anticoagulants when used in combination with antiplatelets.
Journal Article
Non-invasive bioelectrical therapy suppresses retinal neovascularization by modulating cellular metabolism and inflammation
by
Lennikov, Anton
,
Miller, William P.
,
Geniez, Magali Saint
in
Adenosine Triphosphate - metabolism
,
Angiogenesis
,
Animals
2025
Background
Pathological retinal neovascularization, a major cause of blindness, occurs in conditions such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Microglial activation and chronic neuroinflammation play critical roles in disease progression by promoting vascular permeability and angiogenesis. While anti-VEGF therapies are the current standard of care, their efficacy is limited, requiring frequent intraocular injections and raising concerns about long-term retinal health. Noninvasive transpalpebral electrical stimulation (TpES) has emerged as a potential alternative therapy, but its mechanism and therapeutic impact remain poorly understood.
Methods
To investigate the therapeutic effects of TpES, we applied daily microcurrent stimulation (300 µA, 20 Hz, 4 min) in laser-induced choroidal neovascularization (CNV) and streptozotocin (STZ)-induced DR mouse models. Vascular pathology was assessed using fluorescein angiography, optical coherence tomography (OCT), and immunohistochemistry. Mechanistic studies were conducted using primary microglia and human retinal endothelial cells (HREC) to evaluate TpES-induced changes in intracellular calcium ([Ca²⁺]i) signaling, mitochondrial membrane potential, and ATP production. Additionally, human RPE/choroidal explants from healthy, AMD, and DR donors were cultured to assess TpES effects on angiogenesis in healthy and pathological human tissues.
Results
TpES significantly reduced vascular leakage (by ~ 30%,
p
< 0.001) and lesion size in the CNV model (
p
< 0.05), while also suppressing microglial infiltration and VEGF-A expression. In the DR model, TpES attenuated microaneurysm formation, preserved endothelial tight junctions (in vitro). Mechanistic studies revealed that TpES suppressed ATP-induced microglial activation by reducing mitochondrial membrane potential and intracellular ATP levels, leading to depletion of ER calcium stores and inhibition of proinflammatory and proangiogenic signaling. TpES also directly suppressed endothelial cell migration and tube formation, as well as angiogenic sprouting in human RPE/choroidal explants.
Conclusions
These findings establish TpES as a dual-action therapy that mitigates both inflammation and pathological angiogenesis by modulating microglial and endothelial metabolism. Given its noninvasive nature and ability to target key pathways in retinal pathology, TpES represents a promising therapeutic strategy for AMD, DR, and other retinal vascular diseases.
Journal Article
Regulation of intercellular biomolecule transfer–driven tumor angiogenesis and responses to anticancer therapies
2021
Intercellular biomolecule transfer (ICBT) between malignant and benign cells is a major driver of tumor growth, resistance to anticancer therapies, and therapy-triggered metastatic disease. Here we characterized cholesterol 25-hydroxylase (CH25H) as a key genetic suppressor of ICBT between malignant and endothelial cells (ECs) and of ICBT-driven angiopoietin-2-dependent activation of ECs, stimulation of intratumoral angiogenesis, and tumor growth. Human CH25H was downregulated in the ECs from patients with colorectal cancer and the low levels of stromal CH25H were associated with a poor disease outcome. Knockout of endothelial CH25H stimulated angiogenesis and tumor growth in mice. Pharmacologic inhibition of ICBT by reserpine compensated for CH25H loss, elicited angiostatic effects (alone or combined with sunitinib), augmented the therapeutic effect of radio-/chemotherapy, and prevented metastatic disease induced by these regimens. We propose inhibiting ICBT to improve the overall efficacy of anticancer therapies and limit their prometastatic side effects.
Journal Article
SwabExpress: An End-to-End Protocol for Extraction-Free COVID-19 Testing
by
Brandstetter, Elisabeth
,
Zhong, Weizhi
,
McCulloch, Denise J
in
Clinical Laboratory Techniques
,
Coronaviruses
,
COVID-19
2022
Abstract
Background
The urgent need for massively scaled clinical testing for SARS-CoV-2, along with global shortages of critical reagents and supplies, has necessitated development of streamlined laboratory testing protocols. Conventional nucleic acid testing for SARS-CoV-2 involves collection of a clinical specimen with a nasopharyngeal swab in transport medium, nucleic acid extraction, and quantitative reverse-transcription PCR (RT–qPCR). As testing has scaled across the world, the global supply chain has buckled, rendering testing reagents and materials scarce. To address shortages, we developed SwabExpress, an end-to-end protocol developed to employ mass produced anterior nares swabs and bypass the requirement for transport media and nucleic acid extraction.
Methods
We evaluated anterior nares swabs, transported dry and eluted in low-TE buffer as a direct-to-RT–qPCR alternative to extraction-dependent viral transport media. We validated our protocol of using heat treatment for viral inactivation and added a proteinase K digestion step to reduce amplification interference. We tested this protocol across archived and prospectively collected swab specimens to fine-tune test performance.
Results
After optimization, SwabExpress has a low limit of detection at 2–4 molecules/µL, 100% sensitivity, and 99.4% specificity when compared side by side with a traditional RT–qPCR protocol employing extraction. On real-world specimens, SwabExpress outperforms an automated extraction system while simultaneously reducing cost and hands-on time.
Conclusion
SwabExpress is a simplified workflow that facilitates scaled testing for COVID-19 without sacrificing test performance. It may serve as a template for the simplification of PCR-based clinical laboratory tests, particularly in times of critical shortages during pandemics.
Journal Article
A Novel Porcine Model of Bilateral Hindlimb Bypass Graft Surgery Integrating Transit Time Flowmetry
by
Pinto, Nigel V.
,
Vallely, Michael P.
,
Haymet, Andrew B.
in
Analysis
,
Anesthesia
,
Animal models
2024
Background
Bypass graft surgery is a key surgical intervention for ischemic heart disease (coronary bypass graft surgery) and critical limb ischemia (peripheral bypass graft surgery). Graft occlusion remains a significant clinical problem for both types. Further research into the pathobiological mechanisms of graft occlusion are needed in order to design targeted therapeutic strategies.
Methods
Three Large White female pigs (mean weight 52.3 +/- 4.4 kg) received general anaesthesia prior to surgery. The external jugular vein was harvested bilaterally, and a bilateral femoral peripheral arterial bypass was performed, with the superficial femoral artery permanently ligated. The grafts were interrogated immediately post operatively on-table using Medistim MiraQ transit time flowmetry system (Medistim, Oslo, Norway) to assess graft performance. On postoperative day three, the pigs were returned to the operating room, and the grafts were interrogated once again using transit time flowmetry.
Results
Six out of six (100%) successful bilateral EJV to femoral artery bypass grafts were performed. All pigs were successfully recovered, and returned to the operating room at postoperative day 3. The wounds were re-opened and the grafts were inspected. Postoperative graft assessment was performed with transit time flowmetry using the Medistim MiraQTM system (Medistim, Oslo, Norway), demonstrating all grafts were patent (100%).
Conclusion
This model may serve as a platform to gain further mechanistic insight into graft failure pathobiology. By combining a bilateral graft model with gold-standard transit time flowmetry, longitudinal experimentation of targeted therapeutic interventions to combat graft failure may be further studied with improved objectivity.
Journal Article
ELF5 Drives Lung Metastasis in Luminal Breast Cancer through Recruitment of Gr1+ CD11b+ Myeloid-Derived Suppressor Cells
by
Gallego-Ortega, David
,
Conway, James R. W.
,
Roden, Daniel L.
in
Animals
,
Breast cancer
,
Breast Neoplasms - immunology
2015
During pregnancy, the ETS transcription factor ELF5 establishes the milk-secreting alveolar cell lineage by driving a cell fate decision of the mammary luminal progenitor cell. In breast cancer, ELF5 is a key transcriptional determinant of tumor subtype and has been implicated in the development of insensitivity to anti-estrogen therapy. In the mouse mammary tumor virus-Polyoma Middle T (MMTV-PyMT) model of luminal breast cancer, induction of ELF5 levels increased leukocyte infiltration, angiogenesis, and blood vessel permeability in primary tumors and greatly increased the size and number of lung metastasis. Myeloid-derived suppressor cells, a group of immature neutrophils recently identified as mediators of vasculogenesis and metastasis, were recruited to the tumor in response to ELF5. Depletion of these cells using specific Ly6G antibodies prevented ELF5 from driving vasculogenesis and metastasis. Expression signatures in luminal A breast cancers indicated that increased myeloid cell invasion and inflammation were correlated with ELF5 expression, and increased ELF5 immunohistochemical staining predicted much shorter metastasis-free and overall survival of luminal A patients, defining a group who experienced unexpectedly early disease progression. Thus, in the MMTV-PyMT mouse mammary model, increased ELF5 levels drive metastasis by co-opting the innate immune system. As ELF5 has been previously implicated in the development of antiestrogen resistance, this finding implicates ELF5 as a defining factor in the acquisition of the key aspects of the lethal phenotype in luminal A breast cancer.
Journal Article