Selective role for superoxide in InsP3 receptor–mediated mitochondrial dysfunction and endothelial apoptosis

Reactive oxygen species (ROS) play a divergent role in both cell survival and cell death during ischemia/reperfusion (I/R) injury and associated inflammation. In this study, ROS generation by activated macrophages evoked an intracellular Ca2+ ([Ca2+]i) transient in endothelial cells that was ablated by a combination of superoxide dismutase and an anion channel blocker. [Ca2+]i store depletion, but not extracellular Ca2+ chelation, prevented [Ca2+]i elevation in response to O2.− that was inositol 1,4,5-trisphosphate (InsP3) dependent, and cells lacking the three InsP3 receptor (InsP3R) isoforms failed to display the [Ca2+]i transient. Importantly, the O2.−-triggered Ca2+ mobilization preceded a loss in mitochondrial membrane potential that was independent of other oxidants and mitochondrially derived ROS. Activation of apoptosis occurred selectively in response to O2.− and could be prevented by [Ca2+]i buffering. This study provides evidence that O2.− facilitates an InsP3R-linked apoptotic cascade and may serve a critical function in I/R injury and inflammation

Rapid inactivation of airborne bacteria using atmospheric pressure dielectric barrier grating discharge

IEEE Transactions on Plasma Science, 35(5): pp. 1501-1510.Dielectric barrier discharge plasma has been known to inactivate many different microorganisms on surfaces when treatment times are on the order of seconds or minutes in duration. In this paper, a unique plasma air cleaning facility was created which combines a dielectric barrier grating discharge (DBGD) with a filterless laboratory-scale ventilation system and is used to treat concentrated bacterial bioaerosol in a moving air stream at air flow rates of 25 L/s. Results indicate that plasma treatment times on the order of milliseconds corresponding to one pass through the DBGD device can achieve 1.5-log reduction in culturable E. coli immediately after contact with plasma and 5-log reduction totally following in the minutes after the plasma treatment. A numerical characterization study was performed to help predict and understand the mechanism of bacteria inactivation in the DBD plasma from a variety of plasma factors

On Reliability Function of a <i>k</i>-out-of-<i>n</i> System with Decreasing Residual Lifetime of Surviving Components after Their Failures

We consider the reliability function of a k-out-of-n system under conditions that failures of its components lead to an increase in the load on the remaining ones and, consequently, to a change in their residual lifetimes. Development of models able to take into account that failures of a system’s components lead to a decrease in the residual lifetime of the surviving ones is of crucial significance in the system reliability enhancement tasks. This paper proposes a novel approach based on the application of order statistics of the system’s components lifetime to model this situation. An algorithm for calculation of the system reliability function and two moments of its uptime has been developed. Numerical study includes sensitivity analysis for special cases of the considered model based on two real-world systems. The results obtained show the sensitivity of system’s reliability characteristics to the shape of lifetime distribution, as well as to the value of its coefficient of variation at a fixed mean

On Reliability Function of a k-out-of-n System with Decreasing Residual Lifetime of Surviving Components after Their Failures

We consider the reliability function of a k-out-of-n system under conditions that failures of its components lead to an increase in the load on the remaining ones and, consequently, to a change in their residual lifetimes. Development of models able to take into account that failures of a system&rsquo;s components lead to a decrease in the residual lifetime of the surviving ones is of crucial significance in the system reliability enhancement tasks. This paper proposes a novel approach based on the application of order statistics of the system&rsquo;s components lifetime to model this situation. An algorithm for calculation of the system reliability function and two moments of its uptime has been developed. Numerical study includes sensitivity analysis for special cases of the considered model based on two real-world systems. The results obtained show the sensitivity of system&rsquo;s reliability characteristics to the shape of lifetime distribution, as well as to the value of its coefficient of variation at a fixed mean

Identification of the amino acid sequence that targets peroxiredoxin 6 to lysosome-like structures of lung epithelial cells

Peroxiredoxin 6 (Prdx6), an enzyme with glutathione peroxidase and PLA2 (aiPLA2) activities, is highly expressed in respiratory epithelium, where it participates in phospholipid turnover and antioxidant defense. Prdx6 has been localized by immunocytochemistry and subcellular fractionation to acidic organelles (lung lamellar bodies and lysosomes) and cytosol. On the basis of their pH optima, we have postulated that protein subcellular localization determines the balance between the two activities of Prdx6. Using green fluorescent protein-labeled protein expression in alveolar epithelial cell lines, we showed Prdx6 localization to organellar structures resembling lamellar bodies in mouse lung epithelial (MLE-12) cells and lysosomes in A549 cells. Localization within lamellar bodies/lysosomes was in the luminal compartment. Targeting to lysosome-like organelles was abolished by the deletion of amino acids 31–40 from the Prdx6 NH2-terminal region; deletion of the COOH-terminal region had no effect. A green fluorescent protein-labeled peptide containing only amino acids 31–40 showed lysosomal targeting that was abolished by mutation of S32 or G34 within the peptide. Studies with mutated protein indicated that lipid binding was not necessary for Prdx6 targeting. This peptide sequence has no homology to known organellar targeting motifs. These studies indicate that the localization of Prdx6 in acidic organelles and consequent PLA2 activity depend on a novel 10-aa peptide located at positions 31–40 of the protein

Lactate Stimulates Vasculogenic Stem Cells via the Thioredoxin System and Engages an Autocrine Activation Loop Involving Hypoxia-Inducible Factor 1▿

The recruitment and differentiation of circulating stem/progenitor cells (SPCs) in subcutaneous Matrigel in mice was assessed. There were over one million CD34+ SPCs per Matrigel plug 18 h after Matrigel implantation, and including a polymer to elevate the lactate concentration increased the number of SPCs by 3.6-fold. Intricate CD34+ cell-lined channels were linked to the systemic circulation, and lactate accelerated cell differentiation as evaluated based on surface marker expression and cell cycle entry. CD34+ SPCs from lactate-supplemented Matrigel exhibited significantly higher concentrations of thioredoxin 1 (Trx1) and hypoxia-inducible factor 1 (HIF-1) than cells from unsupplemented Matrigel, whereas Trx1 and HIF-1 in CD45+ leukocytes were not elevated by lactate. Results obtained using small inhibitory RNA (siRNA) specific to HIF-1 and mice with conditionally HIF-1 null myeloid cells indicated that SPC recruitment and lactate-mediated effects were dependent on HIF-1. Cells from lactate-supplemented Matrigel had higher concentrations of phosphorylated extracellular signal-regulated kinases 1 and 2, Trx1, Trx reductase (TrxR), vascular endothelial growth factor (VEGF), and stromal cell-derived factor 1 (SDF-1) than cells from unsupplemented Matrigel. SPC recruitment and protein changes were inhibited by siRNA specific to lactate dehydrogenase, TrxR, or HIF-1 and by oxamate, apocynin, U0126, N-acetylcysteine, dithioerythritol, and antibodies to VEGF or SDF-1. Oxidative stress from lactate metabolism by SPCs accelerated further SPC recruitment and differentiation through Trx1-mediated elevations in HIF-1 levels and the subsequent synthesis of HIF-1-dependent growth factors