No abstract

Eosinophils play a primary role in the pathophysiology of asthma. In the lung, the activation state of the infiltrating eosinophils determines the extent of tissue damage. Interleukin-5 (IL-5) and leukotriene B4 (LTB4) are important signaling molecules involved in eosinophil recruitment and activation. However, the physiological processes that regulate these activation events are largely unknown. In this study we have examined the mechanisms of human eosinophil NADPH oxidase regulation by IL-5, LTB4, and phorbol ester (PMA). These stimuli activate a Zn2+-sensitive plasma membrane proton channel, and treatment of eosinophils with Zn2+ blocks superoxide production. We have demonstrated that eosinophil intracellular pH is not altered by IL-5 activation of NADPH oxidase. Additionally, PKCdelta inhibitors block PMA, IL-5 and LTB4 mediated superoxide formation. Interestingly, the PKCdelta-selective inhibitor, rottlerin, does not block proton channel activation by PMA indicating that the oxidase and the proton conductance are regulated at distinct phosphorylation sites. IL-5 and LTB4, but not PMA, stimulated superoxide production is also blocked by inhibitors of PI 3-kinase indicating that activation of this enzyme is an upstream event common to both receptor signaling pathways. Our results indicate that the G-protein-coupled LTB4 receptor and the IL-5 cytokine receptor converge on a common signaling pathway involving PI 3-kinase and PKCdelta to regulate NADPH oxidase activity in human eosinophils.

(+44.4±1.4 mV) increased depolarization compared with PMA alone. Additionally, the protein kinase C (PKC) δ-selective blocker, rottlerin, inhibited PMA-stimulated depolarization, indicating that PKCδ was involved in regulating depolarization associated with eosinophil NADPH oxidase activity. Thus, the membrane depolarization that is associated with NADPH oxidase activation in eosinophils is sufficient to produce marked proton channel activation under physiological conditions.

We describe the development and validation of a new instrument, the Classroom Discourse Observation Protocol (CDOP), which quantifies teacher discourse moves (TDMs) from observational data in undergraduate STEM classrooms. TDMs can be conceptualized as epistemic tools that can mediate classroom discussions. Through an inductive–deductive coding process, we identified commonly occurring TDMs among a group of biology instructors ( n = 13, 37 class session) teaching in Active Learning Environments. We describe the CDOP coding scheme and its associated matrix that allows observers to reliably characterize TDMs in 2-min time intervals over the course of a class period. We present the protocol, discuss how it differs from existing classroom observation protocols, and describe the process by which it was developed and validated. Also, we show how this protocol is able to discriminate the discursive practices of instructors teaching in undergraduate STEM learning environments with sample qualitative and quantitative results that illustrate its utility for assessing and improving STEM instructional practices.