Browsing by Author "Vargo-Gogola, Tracy"
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Item Bisphosphonate-Functionalized Gold Nanoparticles for Contrast-Enhanced X-Ray Detection of Breast Microcalcifications(Elsevier B.V., 2014-02) Cole, Lisa E.; Vargo-Gogola, Tracy; Roeder, Ryan K.; Department of Biochemistry & Molecular Biology, IU School of MedicineMicrocalcifications are one of the most common abnormalities detected by mammography for the diagnosis of breast cancer. However, the detection of microcalcifications and correct diagnosis of breast cancer are limited by the sensitivity and specificity of mammography. Therefore, the objective of this study was to investigate the potential of bisphosphonate-functionalized gold nanoparticles (BP-Au NPs) for contrast-enhanced radiographic detection of breast microcalcifications using two models of breast microcalcifications which allowed for precise control over levels of hydroxyapatite (HA) mineral within a low attenuating matrix. First, an in vitro imaging phantom was prepared with varying concentrations of HA uniformly dispersed in an agarose hydrogel. The X-ray attenuation of HA-agarose compositions labeled by BP-Au NPs was increased by up to 26 HU compared to unlabeled compositions for HA concentrations ranging from 1–10 mg/mL. Second, an ex vivo tissue model was developed to more closely mimic the heterogeneity of breast tissue by injecting varying concentrations of HA in a Matrigel carrier into murine mammary glands. The X-ray attenuation of HA-Matrigel compositions labeled by BP-Au NPs was increased by up to 289 HU compared to unlabeled compositions for HA concentrations ranging from 0.5–25 mg/mL, which included an HA concentration (0.5 mg/mL) that was otherwise undetectable by micro-computed tomography. Cumulatively, both models demonstrated the ability of BP-Au NPs to enhance contrast for radiographic detection of microcalcifications, including at a clinically-relevant imaging resolution. Therefore, BP-Au NPs may have potential to improve clinical detection of breast microcalcifications by mammography.Item Cdc42 overexpression induces hyperbranching in the developing mammary gland by enhancing cell migration(Springer Nature, 2013) Bray, Kristi; Gillette, Melissa; Young, Jeanette; Loughran, Elizabeth; Hwang, Melissa; Sears, James Cooper; Vargo-Gogola, Tracy; Biochemistry and Molecular Biology, School of MedicineIntroduction: The Rho GTPase Cdc42 is overexpressed and hyperactivated in breast tumors compared to normal breast tissue. Cdc42 regulates key processes that are critical for mammary gland morphogenesis and become disrupted during the development, progression, and metastasis of breast cancer. However, the contribution of Cdc42 to normal and neoplastic mammary gland development in vivo remains poorly understood. We were therefore interested in investigating the effects of Cdc42 overexpression on mammary gland morphogenesis as a first step toward understanding how its overexpression may contribute to mammary tumorigenesis. Methods: We developed a tetracycline-regulatable Cdc42 overexpression mouse model in which Cdc42 can be inducibly overexpressed in the developing mammary gland. The effects of Cdc42 overexpression during postnatal mammary gland development were investigated using in vivo and in vitro approaches, including morphometric analysis of wholemounted mammary glands, quantification of histological markers, and primary mammary epithelial cell (MEC) functional and biochemical assays. Results: Analysis of Cdc42-overexpressing mammary glands revealed abnormal terminal end bud (TEB) morphologies, characterized by hyperbudding and trifurcation, and increased side branching within the ductal tree. Quantification of markers of proliferation and apoptosis suggested that these phenotypes were not due to increased cell proliferation or survival. Rather, Cdc42 overexpressing MECs were more migratory and contractile and formed dysmorphic, invasive acini in three-dimensional cultures. Cdc42 and RhoA activities, phosphorylated myosin light chain, and MAPK signaling, which contribute to migration and invasion, were markedly elevated in Cdc42 overexpressing MECs. Interestingly, Cdc42 overexpressing mammary glands displayed several features associated with altered epithelial-stromal interactions, which are known to regulate branching morphogenesis. These included increased stromal thickness and collagen deposition, and stromal cells isolated from Cdc42 overexpressing mammary glands exhibited elevated mRNA expression of extracellular matrix proteins and remodeling enzymes. Conclusions: These data suggest that Cdc42 overexpression disrupts mammary gland branching morphogenesis by altering Rho GTPase and MAPK signaling, leading to increased MEC contractility and migration in association with stromal alterations. Our studies provide insight into how aberrant Cdc42 expression may contribute to mammary tumorigenesis.Item Does viewing pre‐lab dissection summary videos correlate with student performance outcomes in medical gross anatomy?(Wiley, 2025) Kruskie, Megan E.; Wisner, Rebecca L.; Byram, Jessica N.; Vargo-Gogola, Tracy; Deane, Andrew S.; Anatomy, Cell Biology and Physiology, School of MedicinePre-lab summary videos supplement gross anatomy courses by helping students navigate difficult concepts, increasing student confidence, and allowing for content review outside the laboratory. Few studies have examined the direct correlation between video viewing and performance outcomes. This study uses performance outcome data from six consecutive statewide cohorts (2018-2023) at the Indiana University School of Medicine (IUSM) to test the hypothesis that increased video viewing correlates with increased individual student and average cohort performance outcomes. Total number of views and total and average time viewed were aggregated for all student cohorts with access to pre-lab summary videos (2020-2023). Correlations between video viewing variables and student performance (Pearson's R coefficient) were used to determine if video viewing habits predict individual student performance outcomes. A one-way ANOVA with a post hoc Bonferroni correction was used to compare averaged cohort performance outcomes. There is a positive correlation between video viewing and individual student performance outcomes, and increased viewing time predicts higher performance outcomes. Performance outcomes in 2020 were not significantly different from preceding cohorts without video access, but there was a significant increase in all subsequent cohorts (2021-2023). Pre-lab summary videos are a valuable supplement to anatomy instruction that predicts individual student performance outcomes. While significant increases in average cohort performance outcomes in 2021-2023 are coincident with an observed increase in student viewing habits, video viewing is likely one of a varied set of factors that may have contributed to gains in average performance outcomes.Item Effects of bisphosphonate ligands and PEGylation on targeted delivery of gold nanoparticles for contrast-enhanced radiographic detection of breast microcalcifications(Elsevier, 2018) Cole, Lisa E.; McGinnity, Tracie L.; Irimata, Lisa E.; Vargo-Gogola, Tracy; Roeder, Ryan K.; Biochemistry and Molecular Biology, School of MedicineA preclinical murine model of hydroxyapatite (HA) breast microcalcifications (µcals), which are an important clinical biomarker for breast cancer detection, was used to investigate the independent effects of high affinity bisphosphonate (BP) ligands and a polyethylene glycol (PEG) spacer on targeted delivery of gold nanoparticles (Au NPs) for contrast-enhanced radiographic detection. The addition of BP ligands to PEGylated Au NPs (BP-PEG-Au NPs) resulted in five-fold greater binding affinity for targeting HA µcals, as expected, due to the strong binding affinity of BP ligands for calcium. Therefore, BP-PEG-Au NPs were able to target HA µcals in vivo after intramammary delivery, which enabled contrast-enhanced radiographic detection of µcals in both normal and radiographically dense mammary tissues similar to previous results for BP-Au NPs, while PEG-Au NPs did not. The addition of a PEG spacer between the BP targeting ligand and Au NP surface enabled improved in vivo clearance. PEG-Au NPs and BP-PEG-Au NPs were cleared from all mammary glands (MGs) and control MGs, respectively, within 24–48 h after intramammary delivery, while BP-Au NPs were not. PEGylated Au NPs were slowly cleared from MGs by lymphatic drainage and accumulated in the spleen. Histopathology revealed uptake of PEG-Au NPs and BP-PEG-Au NPs by macrophages in the spleen, liver, and MGs; there was no evidence of toxicity due to the accumulation of NPs in organs and tissues compared with untreated controls for up to 28 days after delivery.Item Overcoming Barriers to Providing Narrative Feedback in Pre-clinical Medical Education: Design and Implementation of a Comment Builder Tool(2023-04-28) Hoffman, Leslie A.; Shere, Helen; Bauer, Erich; Vargo-Gogola, TracyFormative feedback is an essential component of competency based medical education1. This feedback should be individualized, reinforce effective behaviors, and provide actionable strategies for improvement. In the first year Human Structure course at Indiana University School of Medicine (IUSM), students complete a two-part assignment to assess the Practice-Based Learning and Improvement competency. Faculty are expected to provide narrative feedback to students on the assignment; however, narrative feedback was not consistently provided to all students in prior years. To lower the barriers to providing feedback, a narrative comment builder tool was developed and implemented. Here we report our experiences with developing and implementing the tool and evaluating ongoing barriers to providing narrative feedback to students.Item P190B RhoGAP Overexpression in the Developing Mammary Epithelium Induces TGFβ-dependent Fibroblast Activation(Public Library of Science, 2013-05-22) Gillette, Melissa; Bray, Kristi; Blumenthaler, Alisa; Vargo-Gogola, Tracy; Biochemistry and Molecular Biology, School of MedicineRho GTPases mediate stromal-epithelial interactions that are important for mammary epithelial cell (MEC) morphogenesis. Increased extracellular matrix (ECM) deposition and reorganization affect MEC morphogenesis in a Rho GTPase-dependent manner. Although the effects of altered ECM on MEC morphogenesis have been described, how MECs regulate stromal deposition is not well understood. Previously, we showed that p190B RhoGAP overexpression disrupts mammary gland morphogenesis by inducing hyperbranching in association with stromal alterations. We therefore hypothesized that MEC overexpression of p190B regulates paracrine interactions to impact fibroblast activation. Using a combination of in vivo morphometric and immunohistochemical analyses and primary cell culture assays, we found that p190B overexpression in MECs activates fibroblasts leading to increased collagen, fibronectin, and laminin production and elevated expression of the collagen crosslinking enzyme lysyl oxidase. Phosphorylation of the TGF-β effector SMAD2 and expression of the TGF-β target gene αSma were increased in p190B-associated fibroblasts, suggesting that elevated TGF-β signaling promoted fibroblast activation. Mechanical tension and TGF-β cooperate to activate fibroblasts. Interestingly, active TGF-β was elevated in conditioned medium from p190B overexpressing MECs compared to control MECs, and p190B overexpressing MECs exhibited increased contractility in a collagen gel contraction assay. These data suggest that paracrine signaling from the p190B overexpressing MECs may activate TGF-β signaling in adjacent fibroblasts. In support of this, transfer of conditioned medium from p190B overexpressing MECs onto wildtype fibroblasts or co-culture of p190B overexpressing MECs with wildtype fibroblasts increased SMAD2 phosphorylation and mRNA expression of ECM genes in the fibroblasts when compared to fibroblasts treated with control CM or co-cultured with control MECs. The increased ECM gene expression and SMAD2 phosphorylation were blocked by treatment with a TGF-β receptor inhibitor. Taken together, these data suggest that p190B overexpression in the mammary epithelium induces fibroblast activation via elevated TGF-β paracrine signaling.Item P190B RhoGAP Regulates Chromosome Segregation in Cancer Cells(MDPI, 2012-04-25) Hwang, Melissa; Peddibhotla, Sirisha; McHenry, Peter; Chang, Peggy; Yochum, Zachary; Park, Ko Un; Sears, James Cooper; Vargo-Gogola, Tracy; Biochemistry and Molecular Biology, School of MedicineRho GTPases are overexpressed and hyperactivated in many cancers, including breast cancer. Rho proteins, as well as their regulators and effectors, have been implicated in mitosis, and their altered expression promotes mitotic defects and aneuploidy. Previously, we demonstrated that p190B Rho GTPase activating protein (RhoGAP) deficiency inhibits ErbB2-induced mammary tumor formation in mice. Here we describe a novel role for p190B as a regulator of mitosis. We found that p190B localized to centrosomes during interphase and mitosis, and that it is differentially phosphorylated during mitosis. Knockdown of p190B expression in MCF-7 and Hela cells increased the incidence of aberrant microtubule-kinetochore attachments at metaphase, lagging chromosomes at anaphase, and micronucleation, all of which are indicative of aneuploidy. Cell cycle analysis of p190B deficient MCF-7 cells revealed a significant increase in apoptotic cells with a concomitant decrease in cells in G1 and S phase, suggesting that p190B deficient cells die at the G1 to S transition. Chemical inhibition of the Rac GTPase during mitosis reduced the incidence of lagging chromosomes in p190B knockdown cells to levels detected in control cells, suggesting that aberrant Rac activity in the absence of p190B promotes chromosome segregation defects. Taken together, these data suggest that p190B regulates chromosome segregation and apoptosis in cancer cells. We propose that disruption of mitosis may be one mechanism by which p190B deficiency inhibits tumorigenesis.Item Student Use and Perceptions of a Human Structure Anki Flashcard Deck(2025-04-25) Peipert, Leah J.; Sondreal, Abigail; Flom, Brandon; Robertson, Kyle; Izah, Ike; Hoffman, Leslie; Vargo-Gogola, Tracy; Husmann, PollyIntroduction: Anki is a free, open-source flashcard software program designed to incorporate spaced repetition that has become a popular study tool among medical students.1,2 Medical schools rarely provide students with an Anki deck correlated with their curriculum, and students instead utilize self-made or publicly available pre-made decks. Study Objectives: Our study aimed to analyze the use and perceptions of a free Anki deck provided to students by the Human Structure course administration. Methods: Medical students were granted access to a Human Structure-specific Anki deck through the course website. Surveys were distributed following completion of the Human Structure course to assess students’ use and perception of the Anki deck. Survey questions addressed frequency and duration of use, barriers to usage, and deck organization, as well as overall satisfaction. Results: Survey respondents included 108 participants, 29% of the Class of 2029. Of those who responded, 83% utilized the provided Anki deck with an average daily usage of 86 minutes. The most common reported barriers to using the Anki deck included “overwhelmed by the number of cards” (65.7%, N=71), “information overload” (40.0%, N=41), and “not enough time” (37.0%, N=40). The majority of respondents found the Anki deck to be “somewhat organized” (45.4%, N=49) or “extremely organized” (18.5%, N=20). The overall satisfaction rating on a scale of zero to 100 was 73. Conclusions: Access to course-specific Anki decks may be a useful tool for students during preclinical medical education.