2,668 research outputs found

    A Comparison of Instructor Professional Development Hours and Student Academic Achievement

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    The problem of this study was to determine if there is a significant positive correlation between Airman Leadership School (ALS) instructors who actively participated in a professional development program and the academic achievement of their trainees

    Kinetic modelling of in vitro data of PI3K, mTOR1, PTEN enzymes and on-target inhibitors Rapamycin, BEZ235, and LY294002

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    The phosphatidylinositide 3-kinases (PI3K) and mammalian target of rapamycin-1 (mTOR1) are two key targets for anti-cancer therapy. Predicting the response of the PI3K/AKT/mTOR1 signalling pathway to targeted therapy is made difficult because of network complexities. Systems biology models can help explore those complexities but the value of such models is dependent on accurate parameterisation. Motivated by a need to increase accuracy in kinetic parameter estimation, and therefore the predictive power of the model, we present a framework to integrate kinetic data from enzyme assays into a unified enzyme kinetic model. We present exemplar kinetic models of PI3K and mTOR1, calibrated on in vitro enzyme data and founded on Michaelis-Menten (MM) approximation. We describe the effects of an allosteric mTOR1 inhibitor (Rapamycin) and ATP-competitive inhibitors (BEZ2235 and LY294002) that show dual inhibition of mTOR1 and PI3K. We also model the kinetics of phosphatase and tensin homolog (PTEN), which modulates sensitivity of the PI3K/AKT/mTOR1 pathway to these drugs. Model validation with independent data sets allows investigation of enzyme function and drug dose dependencies in a wide range of experimental conditions. Modelling of the mTOR1 kinetics showed that Rapamycin has an IC50 independent of ATP concentration and that it is a selective inhibitor of mTOR1 substrates S6K1 and 4EBP1: it retains 40% of mTOR1 activity relative to 4EBP1 phosphorylation and inhibits completely S6K1 activity. For the dual ATP-competitive inhibitors of mTOR1 and PI3K, LY294002 and BEZ235, we derived the dependence of the IC50 on ATP concentration that allows prediction of the IC50 at different ATP concentrations in enzyme and cellular assays. Comparison of the drug effectiveness in enzyme and cellular assays showed that some features of these drugs arise from signalling modulation beyond the on-target action and MM approximation and require a systems-level consideration of the whole PI3K/PTEN/AKT/mTOR1 network in order to understand mechanisms of drug sensitivity and resistance in different cancer cell lines. We suggest that using these models in systems biology investigation of the PI3K/AKT/mTOR1 signalling in cancer cells can bridge the gap between direct drug target action and the therapeutic response to these drugs and their combinations

    Customizing the therapeutic response of signaling networks to promote antitumor responses by drug combinations

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    Drug resistance, de novo and acquired, pervades cellular signaling networks (SNs) from one signaling motif to another as a result of cancer progression and/or drug intervention. This resistance is one of the key determinants of efficacy in targeted anti-cancer drug therapy. Although poorly understood, drug resistance is already being addressed in combination therapy by selecting drug targets where SN sensitivity increases due to combination components or as a result of de novo or acquired mutations. Additionally, successive drug combinations have shown low resistance potential. To promote a rational, systematic development of combination therapies, it is necessary to establish the underlying mechanisms that drive the advantages of combination therapies, and design methods to determine drug targets for combination regimens. Based on a joint systems analysis of cellular SN response and its sensitivity to drug action and oncogenic mutations, we describe an in silico method to analyze the targets of drug combinations. Our method explores mechanisms of sensitizing the SN through a combination of two drugs targeting vertical signaling pathways. We propose a paradigm of SN response customization by one drug to both maximize the effect of another drug in combination and promote a robust therapeutic response against oncogenic mutations. The method was applied to customize the response of the ErbB/PI3K/PTEN/AKT pathway by combination of drugs targeting HER2 receptors and proteins in the down-stream pathway. The results of a computational experiment showed that the modification of the SN response from hyperbolic to smooth sigmoid response by manipulation of two drugs in combination leads to greater robustness in therapeutic response against oncogenic mutations determining cancer heterogeneity. The application of this method in drug combination co-development suggests a combined evaluation of inhibition effects together with the capability of drug combinations to suppress resistance mechanisms before they become clinically manifest

    Interview with Yolande Bavan Member of Lambert, Hendricks and Bavan Vocalist, The Real Ambassadors, 1962 Monterey Jazz Festival Date of Interview: September 23, 2012

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    Dave and Iola Brubeck created The Real Ambassadors in the late 1950s. The jazz musical pointed out the absurdity of segregation and makes the case that artists such as Louis Armstrong are the best and real ambassadors to demonstrate a nation\u27s ideals. It was recorded in 1961 and performed live only once. Despite their efforts, the play never made it to stage. Here is a collection of letters, photographs, scripts, and audio that document the creation of The Real Ambassadors.https://scholarlycommons.pacific.edu/trai/1000/thumbnail.jp

    Compensatory effects in the PI3K/PTEN/AKT signaling network following receptor tyrosine kinase inhibition

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    Overcoming de novo and acquired resistance to anticancer drugs that target signaling networks is a formidable challenge for drug design and effective cancer therapy. Understanding the mechanisms by which this resistance arises may offer a route to addressing the insensitivity of signaling networks to drug intervention and restore the efficacy of anticancer therapy. Extending our recent work identifying PTEN as a key regulator of Herceptin sensitivity, we present an integrated theoretical and experimental approach to study the compensatory mechanisms within the PI3K/PTEN/AKT signaling network that afford resistance to receptor tyrosine kinase (RTK) inhibition by anti-HER2 monoclonal antibodies. In a computational model representing the dynamics of the signaling network, we define a single control parameter that encapsulates the balance of activities of the enzymes involved in the PI3K/PTEN/AKT cycle. By varying this control parameter we are able to demonstrate both distinct dynamic regimes of behavior of the signaling network and the transitions between those regimes. We demonstrate resistance, sensitivity, and suppression of RTK signals by the signaling network. Through model analysis we link the sensitivity-to-resistance transition to specific compensatory mechanisms within the signaling network. We study this transition in detail theoretically by variation of activities of PTEN, PI3K, AKT enzymes, and use the results to inform experiments that perturb the signaling network using combinatorial inhibition of RTK, PTEN, and PI3K enzymes in human ovarian carcinoma cell lines. We find good alignment between theoretical predictions and experimental results. We discuss the application of the results to the challenges of hypersensitivity of the signaling network to RTK signals, suppression of drug resistance, and efficacy of drug combinations in anticancer therapy

    NRF2 regulates HER1 signaling pathway to modulate the sensitivity of ovarian cancer cells to lapatinib and erlotinib

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    NF-E2-related factor 2 (NRF2) regulates the transcription of a battery of metabolic and cytoprotective genes. NRF2 and epidermal growth factor receptors (EGFRs/HERs) are regulators of cellular proliferation and determinants of cancer initiation and progression. NRF2 and HERs confer cancers with resistance to several therapeutic agents. Nevertheless, there is limited understanding of the regulation of HER expression and activation and the link between NRF2 and HER signalling pathways. We show that NRF2 regulates both basal and inducible expression of HER1, as treatment of ovarian cancer cells (PEO1, OVCAR3, and SKOV3) with NRF2 activator tBHQ inducing HER1, while inhibition of NRF2 by siRNA knockdown or with retinoid represses HER1. Furthermore, treatment of cells with tBHQ increased total and phosphorylated NRF2, HER1, and AKT levels and compromised the cytotoxic effect of lapatinib or erlotinib. Treatment with siRNA or retinoid antagonised the effect of tBHQ on NRF2 and HER1 levels and enhanced the sensitivity of ovarian cancer cells to lapatinib or erlotinib. Pharmacological or genetic inhibition of NRF2 and/or treatment with lapatinib or erlotinib elevated cellular ROS and depleted glutathione. This extends the understanding of NRF2 and its regulation of HER family receptors and opens a strategic target for improving cancer therapy

    Are Autonomously Motivated University Instructors More Autonomy-Supportive Teachers?

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    We extended the research on autonomy-supportive teaching to universities and examined the relationships between autonomous motivation to teach and autonomy-supportive teaching. Autonomously motivated university instructors were more autonomy-supportive instructors. The freedom to make pedagogical decisions was negatively correlated with external motivation towards teaching. Participants indicated that large class sizes, high teaching loads, publication pressures, and a culture that undervalues effective undergraduate teaching undermined both student learning and their feelings of autonomy. Together these results presents a picture of a subset of university instructors who remained autonomously motivated to teach, irrespective of barriers they experienced from university administrators or policies

    The Lived Experience of an In-Season Concussion Amongst NCAA Division I Student-Athletes

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    International Journal of Exercise Science 7(1) : 62-74, 2014. The clinical presentation and recovery from a sports-related concussion has been well-documented in the sports medicine literature; however, the post-injury experience of the injured individual has been largely unexplored. Therefore, the purpose of this study was to examine collegiate student-athletes’ lived experiences of an in-season concussion. Four NCAA Division I student-athletes who suffered an in-season concussion were interviewed utilizing an existential phenomenological approach to capture the lived experience of the injury. Five major themes developed from the participants’ experiences: 1) symptoms and emotional response to injury, 2) experiences of concussion testing, 3) fear of failing to meet teammate expectations, 4) support from friends and family, and 5) effect on school. These results provide documented evidence of multiple clinical concerns and anecdotal reports of student-athletes unwillingness to report concussion symptoms, potential dishonesty in reporting post-injury symptoms, negative effects on academic performance, challenges of concussion assessment, and the need to monitor student-athletes activity levels outside athletics. The results of this study can help sports medicine clinicians improve their understanding of the injured student-athlete’s perceptions following an in-season concussion
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