Homocysteine-induced membrane currents, calcium responses and changes in mitochondrial potential in rat cortical neurons

© 2015, Pleiades Publishing, Ltd. Homocysteine, a sulfur-containing amino acid, exerts neurotoxic effects and is involved in the pathogenesis of many neurodegenerative disorders. In contrast to well-studied glutamate excitotoxicity, the mechanism of homocysteine neurotoxicity is not clearly understood. Using wholecell patch-clamp, calcium imaging (fluo-3) and measurements of mitochondrial membrane potential (rhodamine 123), we studied in vitro in cultured rat cortical neurons transmembrane currents, calcium signals and changes in mitochondrial membrane potential induced by homocysteine versus responses induced by NMDA and glutamate. L-homocysteine (50 μM) induced inward currents that were completely blocked by the selective antagonist of NMDA receptors, AP-5. In contrast to NMDA-induced currents, homocysteine-induced currents exhibited a smaller steady-state amplitude. Comparison of calcium responses to homocysteine, NMDA or glutamate demonstrated that in all cortical neurons homocysteine elicited fast oscillatory-type calcium responses, whereas NMDA or glutamate induced a “classical” sustained elevation of intracellular calcium. In contrast to NMDA, homocysteine did not cause a drop in mitochondrial membrane potential at the early stages of its action. However, after its long-term effect, as in cases of NMDA and glutamate, changes in mitochondrial membrane potential arose comparable with its complete drop caused by protonophore FCCP-induced uncoupling of the respiratory chain. Our data suggest that in cultured rat cortical neurons homocysteine at the initial stages of its action induces in vitro neurotoxic effects due to the activation of NMDA-type ionotropic glutamate receptors followed by a massive calcium influx through the channels of these receptors. The long-term effect of homocysteine may lead to mitochondrial dysfuction manifested as a drop in mitochondrial membrane potential

Using action research to improve learning and formative assessment to conduct research

The paper reports on how educational research informed and supported both the process of refinement of introductory physics laboratory instruction and student development of scientific abilities. In particular we focus on how the action research approach paradigm combined with instructional approaches such as scaffolding and formative assessment can be used to design the learning environment, investigate student learning, revise curriculum materials, and conduct subsequent assessment. As the result of the above efforts we found improvement in students’ scientific abilities over the course of three years. We suggest that the process used to improve the curriculum under study can be extended to many instructional innovations.National Science Foundatio

RF assisted switching in magnetic Josephson junctions

We test the effect of an external RF field on the switching processes of magnetic Josephson junctions (MJJs) suitable for the realization of fast, scalable cryogenic memories compatible with Single Flux Quantum logic. We show that the combined application of microwaves and magnetic field pulses can improve the performances of the device, increasing the separation between the critical current levels corresponding to logical "0" and "1." The enhancement of the current level separation can be as high as 80% using an optimal set of parameters. We demonstrate that external RF fields can be used as an additional tool to manipulate the memory states, and we expect that this approach may lead to the development of new methods of selecting MJJs and manipulating their states in memory arrays for various applications

Matrix metalloproteinases in lung biology

Despite much information on their catalytic properties and gene regulation, we actually know very little of what matrix metalloproteinases (MMPs) do in tissues. The catalytic activity of these enzymes has been implicated to function in normal lung biology by participating in branching morphogenesis, homeostasis, and repair, among other events. Overexpression of MMPs, however, has also been blamed for much of the tissue destruction associated with lung inflammation and disease. Beyond their role in the turnover and degradation of extracellular matrix proteins, MMPs also process, activate, and deactivate a variety of soluble factors, and seldom is it readily apparent by presence alone if a specific proteinase in an inflammatory setting is contributing to a reparative or disease process. An important goal of MMP research will be to identify the actual substrates upon which specific enzymes act. This information, in turn, will lead to a clearer understanding of how these extracellular proteinases function in lung development, repair, and disease

The EDS1–PAD4–ADR1 node mediates Arabidopsis pattern-triggered immunity

Plants deploy cell-surface and intracellular leucine rich-repeat domain (LRR) immune receptors to detect pathogens1. LRR receptor kinases and LRR receptor proteins at the plasma membrane recognize microorganism-derived molecules to elicit pattern-triggered immunity (PTI), whereas nucleotide-binding LRR proteins detect microbial effectors inside cells to confer effector-triggered immunity (ETI). Although PTI and ETI are initiated in different host cell compartments, they rely on the transcriptional activation of similar sets of genes2, suggesting pathway convergence upstream of nuclear events. Here we report that PTI triggered by the Arabidopsis LRR receptor protein RLP23 requires signalling-competent dimers of the lipase-like proteins EDS1 and PAD4, and of ADR1 family helper nucleotide-binding LRRs, which are all components of ETI. The cell-surface LRR receptor kinase SOBIR1 links RLP23 with EDS1, PAD4 and ADR1 proteins, suggesting the formation of supramolecular complexes containing PTI receptors and transducers at the inner side of the plasma membrane. We detected similar evolutionary patterns in LRR receptor protein and nucleotide-binding LRR genes across Arabidopsis accessions; overall higher levels of variation in LRR receptor proteins than in LRR receptor kinases are consistent with distinct roles of these two receptor families in plant immunity. We propose that the EDS1–PAD4–ADR1 node is a convergence point for defence signalling cascades, activated by both surface-resident and intracellular LRR receptors, in conferring pathogen immunity

NADPH oxidase elevations in pyramidal neurons drive psychosocial stress-induced neuropathology

Oxidative stress is thought to be involved in the development of behavioral and histopathological alterations in animal models of psychosis. Here we investigate the causal contribution of reactive oxygen species generation by the phagocyte NADPH oxidase NOX2 to neuropathological alterations in a rat model of chronic psychosocial stress. In rats exposed to social isolation, the earliest neuropathological alterations were signs of oxidative stress and appearance of NOX2. Alterations in behavior, increase in glutamate levels and loss of parvalbumin were detectable after 4 weeks of social isolation. The expression of the NOX2 subunit p47phox was markedly increased in pyramidal neurons of isolated rats, but below detection threshold in GABAergic neurons, astrocytes and microglia. Rats with a loss of function mutation in the NOX2 subunit p47phox were protected from behavioral and neuropathological alterations induced by social isolation. To test reversibility, we applied the antioxidant/NOX inhibitor apocynin after initiation of social isolation for a time period of 3 weeks. Apocynin reversed behavioral alterations fully when applied after 4 weeks of social isolation, but only partially after 7 weeks. Our results demonstrate that social isolation induces rapid elevations of the NOX2 complex in the brain. Expression of the enzyme complex was strongest in pyramidal neurons and a loss of function mutation prevented neuropathology induced by social isolation. Finally, at least at early stages, pharmacological targeting of NOX2 activity might reverse behavioral alterations

The Effect of a Paired Lab on Course Completion and Grades in Nonmajors Introductory Biology

This paper explores the effect of a paired lab course on students’ course outcomes in nonmajors introductory biology at the University of Alaska Anchorage. We compare course completion and final grades for 10,793 students (3736 who simultaneously enrolled in the lab and 7057 who did not). Unconditionally, students who self-select into the lab are more likely to complete the course and to earn a higher grade than students who do not. However, when we condition on observable course, academic, and demographic characteristics, we find much of this difference in student performance outcomes is attributable to selection bias, rather than an effect of the lab itself. The data and discussion challenge the misconception that labs serve as recitations for lecture content, noting that the learning objectives of science labs should be more clearly articulated and assessed independent of lecture course outcomes. This paper explores the effect of a paired lab course on students’ course outcomes in introductory biology for nonmajors at the University of Alaska Anchorage (UAA), a large, open-enrollment, 4-year university. We compare outcomes for 10,793 students, 3736 who simultaneously enrolled in the lab and 7057 who did not, and analyze the degree to which they select into the lab on observable characteristics to explore the following research questions: 1. Are students who take a paired lab more likely to complete the lecture component (i.e., receive a final grade as opposed to withdrawing or receiving an Incomplete)? 2. Are students who take a paired lab more likely to receive a higher grade in the lecture component? 3. Does the laboratory experience differently affect course outcomes for students in specific demographic subgroups (e.g., gender, race, high school urbanicity, age, prior academic performance, and socioeconomic status)

INTRODUCTION SCADA-SYSTEM TRACE MODE IN THE MANUFACTURING PROCESSES BASED ON THE BULK STORAGE OF FLOUR

The article presents a model of quality management processes, including milling enterprises using SCADA-systems. It is shown that the flour production in Russia is an important part of agriculture, because it ensures the production of staple food of people flour. Storing flour is an integral and important part of the overall process of making bread and bakery products. If stored properly the processes occurring at the same time in the flour, to a certain extent generally improve its quality. Ultimately, however, depending on the storage conditions for each meal reacts to different binning and consequently the quality of the finished product. In this regard, in the article the importance and necessity of the use of modern information technology in the production process. Presents the architecture of SCADA-system Trace Mode 5.0, internal and external software interfaces for data exchange, the editors for the implementation of individual controls, the functionality of the system to solve strategic problems in the milling, features Trace Mode 5.0 from other popular SCADA-systems. Developed software and hardware system based on SCADA-system Trace Mode 5 to process bulk storage of flour, to choose the best programming languages controllers and interfaces in the system. The basic levels of the control system for controlling the bulk storage of flour. It has been shown that quality management in the company provides collection, processing and analysis of information on the state of material flows and processes at all their stages

Formal strategy for solving problems of management and organization of processes in the transport and logistics systems of the Arctic region

The need for the qualitative development of integrated transport management systems within transport and logistics systems (TLSs) is due to a number of conditions preventing the efficient movement of goods in Russia and its regions. Planning, organization, and management of freight transportation processes in a transport and logistics system is based on the processing of information about the state of objects in the transport and logistics system by processing statistical data. The development of methods for planning, organizing, and managing terminal and warehouse complexes (TWCs) of transport and logistics systems based on optimizing the interaction of transport and logistics infrastructure facilities creates additional prospects for reducing the costs of freight transportation in Russia and its regions. This approach shall be based on the development of scientific and technical solutions for improving the efficiency of TLSs and TWCs. To implement the process of optimizing freight flows within an intelligent transport system based on digital technologies, it is necessary to develop an appropriate mathematical apparatus adapted to specific tasks. The article provides an approach based on the synthesis of computer modeling methods, which makes it possible to conduct an experimental research program based on an integrated methodology for organizing and managing the interaction of TWCs and transport infrastructure facilities. © 2021 Elsevier B.V. All rights reserved

Homocysteine-induced membrane currents, calcium responses and changes in mitochondrial potential in rat cortical neurons

© 2015, Pleiades Publishing, Ltd. Homocysteine, a sulfur-containing amino acid, exerts neurotoxic effects and is involved in the pathogenesis of many neurodegenerative disorders. In contrast to well-studied glutamate excitotoxicity, the mechanism of homocysteine neurotoxicity is not clearly understood. Using wholecell patch-clamp, calcium imaging (fluo-3) and measurements of mitochondrial membrane potential (rhodamine 123), we studied in vitro in cultured rat cortical neurons transmembrane currents, calcium signals and changes in mitochondrial membrane potential induced by homocysteine versus responses induced by NMDA and glutamate. L-homocysteine (50 μM) induced inward currents that were completely blocked by the selective antagonist of NMDA receptors, AP-5. In contrast to NMDA-induced currents, homocysteine-induced currents exhibited a smaller steady-state amplitude. Comparison of calcium responses to homocysteine, NMDA or glutamate demonstrated that in all cortical neurons homocysteine elicited fast oscillatory-type calcium responses, whereas NMDA or glutamate induced a “classical” sustained elevation of intracellular calcium. In contrast to NMDA, homocysteine did not cause a drop in mitochondrial membrane potential at the early stages of its action. However, after its long-term effect, as in cases of NMDA and glutamate, changes in mitochondrial membrane potential arose comparable with its complete drop caused by protonophore FCCP-induced uncoupling of the respiratory chain. Our data suggest that in cultured rat cortical neurons homocysteine at the initial stages of its action induces in vitro neurotoxic effects due to the activation of NMDA-type ionotropic glutamate receptors followed by a massive calcium influx through the channels of these receptors. The long-term effect of homocysteine may lead to mitochondrial dysfuction manifested as a drop in mitochondrial membrane potential