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Sample records for reversible phosphatidylserine exposure

  1. Erythrocyte membrane phosphatidylserine exposure in obesity.

    PubMed

    Solá, Eva; Vayá, Amparo; Martínez, Marcial; Moscardó, Antonio; Corella, Dolores; Santaolaria, Maria-Luisa; España, Francisco; Hernández-Mijares, Antonio

    2009-02-01

    It has been suggested that increased erythrocyte membrane phosphatidylserine (PS) exposure could contribute to hypercoagulability and hemorheological disturbances in obesity. The aim of our study was to evaluate PS exposure in obese patients and in a control group and to correlate this with hemorheological properties, i.e., erythrocyte aggregability (EA) and deformability, and to evaluate the effect of weight loss on these parameters. An anthropometric and analytical evaluation was performed at baseline and after 3 months on a diet (very low-calorie diet for 4 weeks and low-calorie diet for 2 months) on 49 severe or morbid obese patients (37 women, 12 men) and 55 healthy volunteers (39 women, 16 men). PS exposure on erythrocyte membrane was performed by flow cytometry. Erythrocyte aggregation was measured using the Myrenne MA(1) and the Sefam aggregometer. Erythrocyte deformability was determined in a stress diffractometer. Prothrombin fragment F1+2 (F1+2) was determined as a marker of the hypercoagulable state, and plasma malondialdehyde (MDA) as an indicator of oxidative stress. Obese patients had a higher EA index, higher PS exposure on erythrocyte membranes and higher levels of MDA and F1+2. The differences in erythrocyte aggregation and F1+2 between obese patients and the control group were maintained after adjusting for PS exposure. After 3 months of diet, a significant reduction in PS exposure on erythrocyte membrane was observed. Obese patients show increased PS exposure on erythrocyte membrane, with no effect on rheological properties. Increased PS exposure could contribute to hypercoagulability in these patients. Weight loss obtained with diet treatment reduces PS exposure on erythrocyte membrane.

  2. Phosphatidylserine Reversibly Binds Cu2+ with Extremely High Affinity

    PubMed Central

    Monson, Christopher F.; Cong, Xiao; Robison, Aaron; Pace, Hudson P.; Liu, Chunming; Poyton, Matthew F.; Cremer, Paul S.

    2012-01-01

    Phosphatidylserine (PS) embedded within supported lipid bilayers (SLBs) was found to bind Cu2+ from solution with extraordinarily high affinity. In fact, the equilibrium dissociation constant was in the femtomolar range. The resulting complex formed in a 1:2 Cu2+ to PS ratio and quenches a broad spectrum of lipid-bound fluorophores in a reversible and pH-dependent fashion. At acidic pH values, the fluorophores were almost completely unquenched, while at basic pH values significant quenching (85–90%) was observed. The pH at which the transition occurred was dependent on the PS concentration and ranged from approximately pH 5 to 8. The quenching kinetics was slow at low Cu2+ concentrations and basic values pH (up to several hours), while the unquenching reaction was orders of magnitude more rapid upon lowering the pH. This was consistent with diffusion limited complex formation at basic pH, but rapid dissociation under acidic conditions. The tight binding of Cu2+ to PS may have physiological consequences under certain circumstances. PMID:22548290

  3. Stimulation of erythrocyte phosphatidylserine exposure by mercury ions

    SciTech Connect

    Eisele, Kerstin; Lang, Philipp A.; Kempe, Daniela S.; Klarl, Barbara A.; Niemoeller, Olivier; Wieder, Thomas; Huber, Stephan M.; Duranton, Christophe; Lang, Florian . E-mail: florian.lang@uni-tuebingen.de

    2006-01-15

    The sequelae of mercury intoxication include induction of apoptosis. In nucleated cells, Hg{sup 2+}-induced apoptosis involves mitochondrial damage. The present study has been performed to elucidate effects of Hg{sup 2+} in erythrocytes which lack mitochondria but are able to undergo apoptosis-like alterations of the cell membrane. Previous studies have documented that activation of a Ca{sup 2+}-sensitive erythrocyte scramblase leads to exposure of phosphatidylserine at the erythrocyte surface, a typical feature of apoptotic cells. The erythrocyte scramblase is activated by osmotic shock, oxidative stress and/or energy depletion which increase cytosolic Ca{sup 2+} activity and/or activate a sphingomyelinase leading to formation of ceramide. Ceramide sensitizes the scramblase to Ca{sup 2+}. The present experiments explored the effect of Hg{sup 2+} ions on erythrocytes. Phosphatidylserine exposure after mercury treatment was estimated from annexin binding as determined in FACS analysis. Exposure to Hg{sup 2+} (1 {mu}M) indeed significantly increased annexin binding from 2.3 {+-} 0.5% (control condition) to 23 {+-} 6% (n = 6). This effect was paralleled by activation of a clotrimazole-sensitive K{sup +}-selective conductance as measured by patch-clamp recordings and by transient cell shrinkage. Further experiments revealed also an increase of ceramide formation by {approx}66% (n = 7) after challenge with mercury (1 {mu}M). In conclusion, mercury ions activate a clotrimazole-sensitive K{sup +}-selective conductance leading to transient cell shrinkage. Moreover, Hg{sup 2+} increases ceramide formation. The observed mechanisms could similarly participate in the triggering of apoptosis in nucleated cells by Hg{sup 2+}.

  4. Fertilization Induces a Transient Exposure of Phosphatidylserine in Mouse Eggs

    PubMed Central

    Curia, Claudio A.; Ernesto, Juan I.; Stein, Paula; Busso, Dolores; Schultz, Richard M.; Cuasnicu, Patricia S.; Cohen, Débora J.

    2013-01-01

    Phosphatidylserine (PS) is normally localized to the inner leaflet of the plasma membrane and the requirement of PS translocation to the outer leaflet in cellular processes other than apoptosis has been demonstrated recently. In this work we investigated the occurrence of PS mobilization in mouse eggs, which express flippase Atp8a1 and scramblases Plscr1 and 3, as determined by RT-PCR; these enzyme are responsible for PS distribution in cell membranes. We find a dramatic increase in binding of flouresceinated-Annexin-V, which specifically binds to PS, following fertilization or parthenogenetic activation induced by SrCl2 treatment. This increase was not observed when eggs were first treated with BAPTA-AM, indicating that an increase in intracellular Ca2+ concentration was required for PS exposure. Fluorescence was observed over the entire egg surface with the exception of the regions overlying the meiotic spindle and sperm entry site. PS exposure was also observed in activated eggs obtained from CaMKIIγ null females, which are unable to exit metaphase II arrest despite displaying Ca2+ spikes. In contrast, PS exposure was not observed in TPEN-activated eggs, which exit metaphase II arrest in the absence of Ca2+ release. PS exposure was also observed when eggs were activated with ethanol but not with a Ca2+ ionophore, suggesting that the Ca2+ source and concentration are relevant for PS exposure. Last, treatment with cytochalasin D, which disrupts microfilaments, or jasplakinolide, which stabilizes microfilaments, prior to egg activation showed that PS externalization is an actin-dependent process. Thus, the Ca2+ rise during egg activation results in a transient exposure of PS in fertilized eggs that is not associated with apoptosis. PMID:23951277

  5. Phosphatidylserine exposure is required for ADAM17 sheddase function

    PubMed Central

    Sommer, Anselm; Kordowski, Felix; Büch, Joscha; Maretzky, Thorsten; Evers, Astrid; Andrä, Jörg; Düsterhöft, Stefan; Michalek, Matthias; Lorenzen, Inken; Somasundaram, Prasath; Tholey, Andreas; Sönnichsen, Frank D.; Kunzelmann, Karl; Heinbockel, Lena; Nehls, Christian; Gutsmann, Thomas; Grötzinger, Joachim; Bhakdi, Sucharit; Reiss, Karina

    2016-01-01

    ADAM17, a prominent member of the ‘Disintegrin and Metalloproteinase' (ADAM) family, controls vital cellular functions through cleavage of transmembrane substrates. Here we present evidence that surface exposure of phosphatidylserine (PS) is pivotal for ADAM17 to exert sheddase activity. PS exposure is tightly coupled to substrate shedding provoked by diverse ADAM17 activators. PS dependency is demonstrated in the following: (a) in Raji cells undergoing apoptosis; (b) in mutant PSA-3 cells with manipulatable PS content; and (c) in Scott syndrome lymphocytes genetically defunct in their capacity to externalize PS in response to intracellular Ca2+ elevation. Soluble phosphorylserine but not phosphorylcholine inhibits substrate cleavage. The isolated membrane proximal domain (MPD) of ADAM17 binds to PS but not to phosphatidylcholine liposomes. A cationic PS-binding motif is identified in this domain, replacement of which abrogates liposome-binding and renders the protease incapable of cleaving its substrates in cells. We speculate that surface-exposed PS directs the protease to its targets where it then executes its shedding function. PMID:27161080

  6. The cholesterol content of the erythrocyte membrane is an important determinant of phosphatidylserine exposure.

    PubMed

    van Zwieten, Rob; Bochem, Andrea E; Hilarius, Petra M; van Bruggen, Robin; Bergkamp, Ferry; Hovingh, G Kees; Verhoeven, Arthur J

    2012-12-01

    Maintenance of the asymmetric distribution of phospholipids across the plasma membrane is a prerequisite for the survival of erythrocytes. Various stimuli have been shown to induce scrambling of phospholipids and thereby exposure of phosphatidylserine (PS). In two types of patients, both with aberrant plasma cholesterol levels, we observed an aberrant PS exposure in erythrocytes upon stimulation. We investigated the effect of high and low levels of cholesterol on the ATP-dependent flippase, which maintains phospholipid asymmetry, and the ATP-independent scrambling activity, which breaks down phospholipid asymmetry. We analyzed erythrocytes of a patient with spur cell anemia, characterized by elevated plasma cholesterol, and the erythrocytes of Tangier disease patients with very low levels of plasma cholesterol. In normal erythrocytes, loaded with cholesterol or depleted of cholesterol in vitro, the same analyses were performed. Changes in the cholesterol/phospholipid ratio of erythrocytes had marked effects on PS exposure upon cell activation. Excess cholesterol profoundly inhibited PS exposure, whereas cholesterol depletion led to increased PS exposure. The activity of the ATP-dependent flippase was not changed, suggesting a major influence of cholesterol on the outward translocation of PS. The effects of cholesterol were not accompanied by eminent changes in cytoskeletal and membrane proteins. These findings emphasize the importance of cholesterol exchange between circulating plasma and the erythrocyte membrane as determinant for phosphatidylserine exposure in erythrocytes.

  7. Detection of phosphatidylserine exposure on leukocytes following treatment with human galectins.

    PubMed

    Arthur, Connie M; Rodrigues, Lilian Cataldi; Baruffi, Marcelo Dias; Sullivan, Harold C; Cummings, Richard D; Stowell, Sean R

    2015-01-01

    Cellular turnover represents a fundamental aspect of immunological homeostasis. While many factors appear to regulate leukocyte removal during inflammatory resolution, recent studies suggest that members of the galectin family play a unique role in orchestrating this process. Unlike cellular removal through apoptotic cell death, several members of the galectin family induce surface expression of phosphatidylserine (PS), a phagocytic marker on cells undergoing apoptosis, in the absence of cell death. However, similar to PS on cells undergoing apoptosis, galectin-induced PS exposure sensitizes cells to phagocytic removal. As galectins appear to prepare cells for phagocytic removal without actually inducing apoptotic cell death, this process has recently been coined preaparesis. Given the unique characteristics of galectin-induced PS exposure in the context of preaparesis, we will examine important considerations when evaluating the potential impact of different galectin family members on PS exposure and cell viability.

  8. Aminoglycoside-induced phosphatidylserine externalisation in sensory hair cells is regionally restricted, rapid and reversible

    PubMed Central

    Goodyear, R.J.; Gale, J.E.; Ranatunga, K.M.; Kros, C.J.; Richardson, G.P.

    2012-01-01

    The aminophospholipid phosphatidylserine (PS) is normally restricted to the inner leaflet of the plasmalemma. During certain cellular processes, including apoptosis, PS translocates to the outer leaflet and can be labelled with externally-applied annexin-V, a calcium-dependent PS-binding protein. In mouse cochlear cultures, annexin-V labelling reveals the aminoglycoside antibiotic neomycin induces rapid PS externalisation, specifically on the apical surface of hair cells. PS externalisation is observed within ~75 seconds of neomycin perfusion, first on the hair bundle and then on membrane blebs forming around the apical surface. Whole-cell capacitance also increases significantly within minutes of neomycin application indicating blebbing is accompanied by membrane addition to the hair-cell surface. PS-externalisation and membrane blebbing can, nonetheless, occur independently. Pre-treating hair cells with calcium chelators, a procedure that blocks mechanotransduction, or overexpressing a PIP2-binding pleckstrin-homology domain, can reduce neomycin-induced PS externalisation, suggesting neomycin enters hair cells via transduction channels, clusters PIP2, and thereby activates lipid scrambling. The effects of short-term neomycin treatment are reversible. Following neomycin washout, PS is no longer detected on the apical surface, apical membrane blebs disappear and surface-bound annexin-V is internalised, distributing throughout the supra-nuclear cytoplasm of the hair cell. Hair cells can therefore repair, and recover from, neomycin-induced surface damage. Hair cells lacking myosin VI, a minus-end directed actin-based motor implicated in endocytosis, can also recover from brief neomycin treatment. Internalised annexin-V, however, remains below the apical surface thereby pinpointing a critical role for myosin VI in the transport of endocytosed material away from the hair cell’s periphery. PMID:18829952

  9. TMEM16F is required for phosphatidylserine exposure and microparticle release in activated mouse platelets.

    PubMed

    Fujii, Toshihiro; Sakata, Asuka; Nishimura, Satoshi; Eto, Koji; Nagata, Shigekazu

    2015-10-13

    Phosphatidylserine (PtdSer) exposure on the surface of activated platelets requires the action of a phospholipid scramblase(s), and serves as a scaffold for the assembly of the tenase and prothrombinase complexes involved in blood coagulation. Here, we found that the activation of mouse platelets with thrombin/collagen or Ca(2+) ionophore at 20 °C induces PtdSer exposure without compromising plasma membrane integrity. Among five transmembrane protein 16 (TMEM16) members that support Ca(2+)-dependent phospholipid scrambling, TMEM16F was the only one that showed high expression in mouse platelets. Platelets from platelet-specific TMEM16F-deficient mice exhibited defects in activation-induced PtdSer exposure and microparticle shedding, although α-granule and dense granule release remained intact. The rate of tissue factor-induced thrombin generation by TMEM16F-deficient platelets was severely reduced, whereas thrombin-induced clot retraction was unaffected. The imaging of laser-induced thrombus formation in whole animals showed that PtdSer exposure on aggregated platelets was TMEM16F-dependent in vivo. The phenotypes of the platelet-specific TMEM16F-null mice resemble those of patients with Scott syndrome, a mild bleeding disorder, indicating that these mice may provide a useful model for human Scott syndrome. PMID:26417084

  10. TMEM16F is required for phosphatidylserine exposure and microparticle release in activated mouse platelets

    PubMed Central

    Fujii, Toshihiro; Sakata, Asuka; Nishimura, Satoshi; Eto, Koji; Nagata, Shigekazu

    2015-01-01

    Phosphatidylserine (PtdSer) exposure on the surface of activated platelets requires the action of a phospholipid scramblase(s), and serves as a scaffold for the assembly of the tenase and prothrombinase complexes involved in blood coagulation. Here, we found that the activation of mouse platelets with thrombin/collagen or Ca2+ ionophore at 20 °C induces PtdSer exposure without compromising plasma membrane integrity. Among five transmembrane protein 16 (TMEM16) members that support Ca2+-dependent phospholipid scrambling, TMEM16F was the only one that showed high expression in mouse platelets. Platelets from platelet-specific TMEM16F-deficient mice exhibited defects in activation-induced PtdSer exposure and microparticle shedding, although α-granule and dense granule release remained intact. The rate of tissue factor-induced thrombin generation by TMEM16F-deficient platelets was severely reduced, whereas thrombin-induced clot retraction was unaffected. The imaging of laser-induced thrombus formation in whole animals showed that PtdSer exposure on aggregated platelets was TMEM16F-dependent in vivo. The phenotypes of the platelet-specific TMEM16F-null mice resemble those of patients with Scott syndrome, a mild bleeding disorder, indicating that these mice may provide a useful model for human Scott syndrome. PMID:26417084

  11. Phosphatidylserine exposure and red cell viability in red cell aging and in hemolytic anemia

    PubMed Central

    Boas, Franz Edward; Forman, Linda; Beutler, Ernest

    1998-01-01

    Phosphatidylserine (PS) normally localizes to the inner leaflet of cell membranes but becomes exposed in abnormal or apoptotic cells, signaling macrophages to ingest them. Along similar lines, it seemed possible that the removal of red cells from circulation because of normal aging or in hemolytic anemias might be triggered by PS exposure. To investigate the role of PS exposure in normal red cell aging, we used N-hydroxysuccinimide-biotin to tag rabbit red cells in vivo, then used phycoerythrin-streptavidin to label the biotinylated cells, and annexin V-fluorescein isothiocyanate (FITC) to detect the exposed PS. Flow cytometric analysis of these cells drawn at 10-day intervals up to 70 days after biotinylation indicated that older, biotinylated cells expose more PS. Furthermore, our data match a simple model of red cell senescence that assumes both an age-dependent destruction of senescent red cells preceded by several hours of PS exposure and a random destruction of red cells without PS exposure. By using this model, we demonstrated that the exposure of PS parallels the rate at which biotinylated red cells are removed from circulation. On the other hand, using an annexin V-FITC label and flow cytometry demonstrates that exposed PS does not cause the reduced red cell life span of patients with hemolytic anemia, with the possible exception of those with unstable hemoglobins or sickle cell anemia. Thus, in some cases PS exposure on the cell surface may signal the removal of red cells from circulation, but in other cases some other signal must trigger the sequestration of cells. PMID:9501218

  12. Protein kinase C activation induces phosphatidylserine exposure on red blood cells.

    PubMed

    de Jong, Kitty; Rettig, Michael P; Low, Philip S; Kuypers, Frans A

    2002-10-15

    We have shown previously that red blood cells (RBCs) can be induced to influx Ca(2+) when treated with lipid mediators, such as lysophosphatidic acid and prostaglandin E(2), that are released during clot formation. Since calcium loading of RBCs can lead to both protein kinase C (PKC) activation and phosphatidylserine (PS) exposure, we decided to investigate the possible linkage between PKC activation and membrane PS scrambling using phorbol 12-myristate-13-acetate (PMA), a commonly used activator of PKC. Treatment of RBCs with PMA in a calcium-containing buffer caused immediate PS exposure in an RBC subpopulation. The size of the subpopulation did not change upon further incubation, indicating that not all RBCs are equally susceptible to this treatment. Using a fluorescent indicator, we found a subpopulation of RBCs with elevated intracellular calcium levels. In the absence of extracellular calcium, no PS exposure was found. However, we did find cells with high levels of calcium that did not expose PS, and a variable percentage of PS-exposing cells that did not show elevated calcium concentrations. Inhibition of PKC with either calphostin C, a blocker of the PMA binding site, or chelerythrine chloride, an inhibitor of the active site, diminished the level of formation of PS-exposing cells. However, the inhibitors had different effects on calcium internalization, indicating that a high calcium concentration alone was not responsible for inducing PS exposure in the absence of PKC activity. Moreover, PKC inhibition could prevent PS exposure induced by calcium and ionophore treatment of RBCs. We conclude that PKC is implicated in the mechanism of membrane phospholipid scrambling.

  13. Indolic uremic solutes enhance procoagulant activity of red blood cells through phosphatidylserine exposure and microparticle release.

    PubMed

    Gao, Chunyan; Ji, Shuting; Dong, Weijun; Qi, Yushan; Song, Wen; Cui, Debin; Shi, Jialan

    2015-11-01

    Increased accumulation of indolic uremic solutes in the blood of uremic patients contributes to the risk of thrombotic events. Red blood cells (RBCs), the most abundant blood cells in circulation, may be a privileged target of these solutes. However, the effect of uremic solutes indoxyl sulfate (IS) and indole-3-acetic acid (IAA) on procoagulant activity (PCA) of erythrocyte is unclear. Here, RBCs from healthy adults were treated with IS and IAA (mean and maximal concentrations reported in uremic patients). Phosphatidylserine (PS) exposure of RBCs and their microparticles (MPs) release were labeled with Alexa Fluor 488-lactadherin and detected by flow cytometer. Cytosolic Ca(2+) ([Ca(2+)]) with Fluo 3/AM was analyzed by flow cytometer. PCA was assessed by clotting time and purified coagulation complex assays. We found that PS exposure, MPs generation, and consequent PCA of RBCs at mean concentrations of IS and IAA enhanced and peaked in maximal uremic concentrations. Moreover, 128 nM lactadherin, a PS inhibitor, inhibited over 90% PCA of RBCs and RMPs. Eryptosis or damage, by indolic uremic solutes was due to, at least partially, the increase of cytosolic [Ca(2+)]. Our results suggest that RBC eryptosis in uremic solutes IS and IAA plays an important role in thrombus formation through releasing RMPs and exposing PS. Lactadherin acts as an efficient anticoagulant in this process. PMID:26516916

  14. A homogeneous time-resolved fluorescence resonance energy transfer assay for phosphatidylserine exposure on apoptotic cells.

    PubMed

    Gasser, Jean-Philippe; Hehl, Michaela; Millward, Thomas A

    2009-01-01

    A simple, "mix-and-measure" microplate assay for phosphatidylserine (PtdSer) exposure on the surface of apoptotic cells is described. The assay exploits the fact that annexin V, a protein with high affinity and specificity for PtdSer, forms trimers and higher order oligomers on binding to membranes containing PtdSer. The transition from soluble monomer to cell-bound oligomer is detected using time-resolved fluorescence resonance energy transfer from europium chelate-labeled annexin V to Cy5-labeled annexin V. PtdSer detection is achieved by a single addition of a reagent mix containing labeled annexins and calcium ions directly to cell cultures in a 96-well plate, followed by a brief incubation before fluorescence measurement. The assay can be used to quantify PtdSer exposure on both suspension cells and adherent cells in situ. This method is simpler and faster than existing annexin V binding assays based on flow cytometry or microscopy, and it yields precise data with Z' values of 0.6-0.7. PMID:18835236

  15. 4.1R-deficient human red blood cells have altered phosphatidylserine exposure pathways and are deficient in CD44 and CD47 glycoproteins

    PubMed Central

    Jeremy, Kris P.; Plummer, Zoe E.; Head, David J.; Madgett, Tracey E.; Sanders, Kelly L.; Wallington, Amanda; Storry, Jill R.; Gilsanz, Florinda; Delaunay, Jean; Avent, Neil D.

    2009-01-01

    Background Protein 4.1R is an important component of the red cell membrane skeleton. It imparts structural integrity and has transmembrane signaling roles by direct interactions with transmembrane proteins and other membrane skeletal components, notably p55 and calmodulin. Design and Methods Spontaneous and ligation-induced phosphatidylserine exposure on erythrocytes from two patients with 4.1R deficiency were studied, using CD47 glycoprotein and glycophorin C as ligands. We also looked for protein abnormalities in the 4.1R - based multiprotein complex. Results Phosphatidylserine exposure was significantly increased in 4.1R-deficient erythrocytes obtained from the two different individuals when ligands to CD47 glycoprotein were bound. Spontaneous phosphatidylserine exposure was normal. 4.1R, glycophorin C and p55 were missing or sharply reduced. Furthermore there was an alteration or deficiency of CD47 glycoprotein and a lack of CD44 glycoprotein. Based on a recent study in 4.1R-deficient mice, we found that there are clear functional differences between interactions of human red cell 4.1R and its murine counterpart. Conclusions Glycophorin C is known to bind 4.1R, and we have defined previously that it also binds CD47. From our evidence, we suggest that 4.1R plays a role in the phosphatidylserine exposure signaling pathway that is of fundamental importance in red cell turnover. The linkage of CD44 to 4.1R may be relevant to this process. PMID:19794081

  16. 14-3-3ζ regulates the mitochondrial respiratory reserve linked to platelet phosphatidylserine exposure and procoagulant function

    PubMed Central

    Schoenwaelder, Simone M.; Darbousset, Roxane; Cranmer, Susan L.; Ramshaw, Hayley S.; Orive, Stephanie L.; Sturgeon, Sharelle; Yuan, Yuping; Yao, Yu; Krycer, James R.; Woodcock, Joanna; Maclean, Jessica; Pitson, Stuart; Zheng, Zhaohua; Henstridge, Darren C.; van der Wal, Dianne; Gardiner, Elizabeth E.; Berndt, Michael C.; Andrews, Robert K.; James, David E.; Lopez, Angel F.; Jackson, Shaun P.

    2016-01-01

    The 14-3-3 family of adaptor proteins regulate diverse cellular functions including cell proliferation, metabolism, adhesion and apoptosis. Platelets express numerous 14-3-3 isoforms, including 14-3-3ζ, which has previously been implicated in regulating GPIbα function. Here we show an important role for 14-3-3ζ in regulating arterial thrombosis. Interestingly, this thrombosis defect is not related to alterations in von Willebrand factor (VWF)–GPIb adhesive function or platelet activation, but instead associated with reduced platelet phosphatidylserine (PS) exposure and procoagulant function. Decreased PS exposure in 14-3-3ζ-deficient platelets is associated with more sustained levels of metabolic ATP and increased mitochondrial respiratory reserve, independent of alterations in cytosolic calcium flux. Reduced platelet PS exposure in 14-3-3ζ-deficient mice does not increase bleeding risk, but results in decreased thrombin generation and protection from pulmonary embolism, leading to prolonged survival. Our studies define an important role for 14-3-3ζ in regulating platelet bioenergetics, leading to decreased platelet PS exposure and procoagulant function. PMID:27670677

  17. Activation of the alternative complement pathway by exposure of phosphatidylethanolamine and phosphatidylserine on erythrocytes from sickle cell disease patients.

    PubMed Central

    Wang, R H; Phillips, G; Medof, M E; Mold, C

    1993-01-01

    Deoxygenation of erythrocytes from sickle cell anemia (SCA) patients alters membrane phospholipid distribution with increased exposure of phosphatidylethanolamine (PE) and phosphatidylserine (PS) on the outer leaflet. This study investigated whether altered membrane phospholipid exposure on sickle erythrocytes results in complement activation. In vitro deoxygenation of sickle but not normal erythrocytes resulted in complement activation measured by C3 binding. Additional evidence indicated that this activation was the result of the alterations in membrane phospholipids. First, complement was activated by normal erythrocytes after incubation with sodium tetrathionate, which produces similar phospholipid changes. Second, antibody was not required for complement activation by sickle or tetrathionate-treated erythrocytes. Third, the membrane regulatory proteins, decay-accelerating factor (CD55) and the C3b/C4b receptor (CD35), were normal on sickle and tetrathionate-treated erythrocytes. Finally, insertion of PE or PS into normal erythrocytes induced alternative pathway activation. SCA patients in crisis exhibited increased plasma factor Bb levels compared with baseline, and erythrocytes isolated from hospitalized SCA patients had increased levels of bound C3, indicating that alternative pathway activation occurs in vivo. Activation of complement may be a contributing factor in sickle crisis episodes, shortening the life span of erythrocytes and decreasing host defense against infections. Images PMID:7690777

  18. Trivalent methylated arsenical-induced phosphatidylserine exposure and apoptosis in platelets may lead to increased thrombus formation

    SciTech Connect

    Bae, Ok-Nam; Lim, Kyung-Min; Chung, Jin-Ho

    2009-09-01

    Trivalent methylated metabolites of arsenic, monomethylarsonous acid (MMA{sup III}) and dimethylarsinous acid (DMA{sup III}), have been found highly reactive and toxic in various cells and in vivo animal models, suggesting their roles in the arsenic-associated toxicity. However, their effects on cardiovascular system including blood cells, one of the most important targets for arsenic toxicity, remain poorly understood. Here we found that MMA{sup III} and DMA{sup III} could induce procoagulant activity and apoptosis in platelets, which play key roles in the development of various cardiovascular diseases (CVDs) through excessive thrombus formation. In freshly isolated human platelets, treatment of MMA{sup III} resulted in phosphatidylserine (PS) exposure, a hallmark of procoagulant activation, accompanied by distinctive apoptotic features including mitochondrial membrane potential disruption, cytochrome c release, and caspase-3 activation. These procoagulant activation and apoptotic features were found to be mediated by the depletion of protein thiol and intracellular ATP, and flippase inhibition by MMA{sup III}, while the intracellular calcium increase or reactive oxygen species generation was not involved. Importantly, increased platelet procoagulant activity by MMA{sup III} resulted in enhanced blood coagulation and excessive thrombus formation in a rat in vivo venous thrombosis model. DMA{sup III} also induced PS-exposure with apoptotic features mediated by protein thiol depletion, which resulted in enhanced thrombin generation. In summary, we believe that this study provides an important evidence for the role of trivalent methylated arsenic metabolites in arsenic-associated CVDs, giving a novel insight into the role of platelet apoptosis in toxicant-induced cardiovascular toxicity.

  19. Distinct Modes of Macrophage Recognition for Apoptotic and Necrotic Cells Are Not Specified Exclusively by Phosphatidylserine Exposure

    PubMed Central

    Cocco, Regina E.; Ucker, David S.

    2001-01-01

    The distinction between physiological (apoptotic) and pathological (necrotic) cell deaths reflects mechanistic differences in cellular disintegration and is of functional significance with respect to the outcomes that are triggered by the cell corpses. Mechanistically, apoptotic cells die via an active and ordered pathway; necrotic deaths, conversely, are chaotic and passive. Macrophages and other phagocytic cells recognize and engulf these dead cells. This clearance is believed to reveal an innate immunity, associated with inflammation in cases of pathological but not physiological cell deaths. Using objective and quantitative measures to assess these processes, we find that macrophages bind and engulf native apoptotic and necrotic cells to similar extents and with similar kinetics. However, recognition of these two classes of dying cells occurs via distinct and noncompeting mechanisms. Phosphatidylserine, which is externalized on both apoptotic and necrotic cells, is not a specific ligand for the recognition of either one. The distinct modes of recognition for these different corpses are linked to opposing responses from engulfing macrophages. Necrotic cells, when recognized, enhance proinflammatory responses of activated macrophages, although they are not sufficient to trigger macrophage activation. In marked contrast, apoptotic cells profoundly inhibit phlogistic macrophage responses; this represents a cell-associated, dominant-acting anti-inflammatory signaling activity acquired posttranslationally during the process of physiological cell death. PMID:11294896

  20. Role of Calcium in Phosphatidylserine Externalisation in Red Blood Cells from Sickle Cell Patients

    PubMed Central

    Weiss, Erwin; Rees, David Charles; Gibson, John Stanley

    2011-01-01

    Phosphatidylserine exposure occurs in red blood cells (RBCs) from sickle cell disease (SCD) patients and is increased by deoxygenation. The mechanisms responsible remain unclear. RBCs from SCD patients also have elevated cation permeability, and, in particular, a deoxygenation-induced cation conductance which mediates Ca2+ entry, providing an obvious link with phosphatidylserine exposure. The role of Ca2+ was investigated using FITC-labelled annexin. Results confirmed high phosphatidylserine exposure in RBCs from SCD patients increasing upon deoxygenation. When deoxygenated, phosphatidylserine exposure was further elevated as extracellular [Ca2+] was increased. This effect was inhibited by dipyridamole, intracellular Ca2+ chelation, and Gardos channel inhibition. Phosphatidylserine exposure was reduced in high K+ saline. Ca2+ levels required to elicit phosphatidylserine exposure were in the low micromolar range. Findings are consistent with Ca2+ entry through the deoxygenation-induced pathway (Psickle), activating the Gardos channel. [Ca2+] required for phosphatidylserine scrambling are in the range achievable in vivo. PMID:21490763

  1. Activated microglia cause reversible apoptosis of pheochromocytoma cells, inducing their cell death by phagocytosis.

    PubMed

    Hornik, Tamara C; Vilalta, Anna; Brown, Guy C

    2016-01-01

    Some apoptotic processes, such as phosphatidylserine exposure, are potentially reversible and do not necessarily lead to cell death. However, phosphatidylserine exposure can induce phagocytosis of a cell, resulting in cell death by phagocytosis: phagoptosis. Phagoptosis of neurons by microglia might contribute to neuropathology, whereas phagoptosis of tumour cells by macrophages might limit cancer. Here, we examined the mechanisms by which BV-2 microglia killed co-cultured pheochromocytoma (PC12) cells that were either undifferentiated or differentiated into neuronal cells. We found that microglia activated by lipopolysaccharide rapidly phagocytosed PC12 cells. Activated microglia caused reversible phosphatidylserine exposure on and reversible caspase activation in PC12 cells, and caspase inhibition prevented phosphatidylserine exposur and decreased subsequent phagocytosis. Nitric oxide was necessary and sufficient to induce the reversible phosphatidylserine exposure and phagocytosis. The PC12 cells were not dead at the time they were phagocytised, and inhibition of their phagocytosis left viable cells. Cell loss was inhibited by blocking phagocytosis mediated by phosphatidylserine, MFG-E8, vitronectin receptors or P2Y6 receptors. Thus, activated microglia can induce reversible apoptosis of target cells, which is insufficient to cause apoptotic cell death, but sufficient to induce their phagocytosis and therefore cell death by phagoptosis.

  2. Brief reversible bronchospasm resulting from bichromate exposure.

    PubMed

    Shirakawa, T; Morimoto, K

    1996-01-01

    A 50-y-old male worker developed an asthmatic reaction after exposure to bichromate in a metal-plating plant. Evaluation included skin tests, bronchial provocation tests, and specific radioallergosorbent tests with metal salts. A 49-y-old worker who suffered from hard metal asthma was the control. These workers were not atopic, and they exhibited similar bronchial hyperresponsiveness in methacholine-PC20 (74 mg/ml versus 81 mg/ml, respectively) and IgE titers (129 IU/ml versus 130 IU/ml). Positive intradermal and patch tests to bichromate were found in the subject. A bronchial provocation test with inhalation of .01 % bichromate produced an immediate decrease in forced vital capacity in 1 s, followed by a rapid recovery within 5 min absent any treatment. There was no reaction to cobalt (1% cobalt chloride) or to nickel (2% nickel sulfate) salts. In the control, a positive bronchial provocation occurred (absent chromium) with cobalt and nickel. Administration of a subcutaneous preparation of 1 mg atropine sulfate or of 1 puff of disodium cromoglycate or beta-stimulant reduced bronchial responsiveness to methacholine-PC20, and no asthmatic reaction occurred following inhalation of 1% bichromate. No blocking of asthmatic reaction occurred after pretreatment with beclomethasone dipropionate inhalation. Administration of propranolol, however, potentiated the acute bronchoconstriction induced by bichromate. The 50-y-old worker had evidence of IgE antibody to chromium-conjugated human serum albumin and to chromium-conjugated exchange resin. His serum selectively bound 51Cr, but antibodies specific to cobalt and nickel were absent. These results, if viewed collectively, suggest that bichromate exposure causes brief reversible bronchospasm via alteration of autonomic balance and increased vagal activation.

  3. Binding of Alphaherpesvirus Glycoprotein H to Surface α4β1-Integrins Activates Calcium-Signaling Pathways and Induces Phosphatidylserine Exposure on the Plasma Membrane

    PubMed Central

    Gramatica, Andrea; Herrmann, Andreas; Osterrieder, Nikolaus

    2015-01-01

    ABSTRACT Intracellular signaling connected to integrin activation is known to induce cytoplasmic Ca2+ release, which in turn mediates a number of downstream signals. The cellular entry pathways of two closely related alphaherpesviruses, equine herpesviruses 1 and 4 (EHV-1 and EHV-4), are differentially regulated with respect to the requirement of interaction of glycoprotein H (gH) with α4β1-integrins. We show here that binding of EHV-1, but not EHV-4, to target cells resulted in a rapid and significant increase in cytosolic Ca2+ levels. EHV-1 expressing EHV-4 gH (gH4) in lieu of authentic gH1 failed to induce Ca2+ release, while EHV-4 with gH1 triggered significant Ca2+ release. Blocking the interaction between gH1 and α4β1-integrins, inhibiting phospholipase C (PLC) activation, or blocking binding of inositol 1,4,5-triphosphate (IP3) to its receptor on the endoplasmic reticulum (ER) abrogated Ca2+ release. Interestingly, phosphatidylserine (PS) was exposed on the plasma membrane in response to cytosolic calcium increase after EHV-1 binding through a scramblase-dependent mechanism. Inhibition of both Ca2+ release from the ER and scramblase activation blocked PS scrambling and redirected virus entry to the endocytic pathway, indicating that PS may play a role in facilitating virus entry directly at the plasma membrane. PMID:26489864

  4. Brief Exposure to Secondhand Smoke Reversibly Impairs Endothelial Vasodilatory Function

    PubMed Central

    2014-01-01

    Introduction: We sought to determine the effects of brief exposures to low concentrations of tobacco secondhand smoke (SHS) on arterial flow-mediated dilation (FMD, a nitric oxide-dependent measure of vascular endothelial function), in a controlled animal model never before exposed to smoke. In humans, SHS exposure for 30min impairs FMD. It is important to gain a better understanding of the acute effects of exposure to SHS at low concentrations and for brief periods of time. Methods: We measured changes in FMD in rats exposed to a range of real-world levels of SHS for durations of 30min, 10min, 1min, and 4 breaths (roughly 15 s). Results: We observed a dose-response relationship between SHS particle concentration over 30min and post-exposure impairment of FMD, which was linear through the range typically encountered in smoky restaurants and then saturated at higher concentrations. One min of exposure to SHS at moderate concentrations was sufficient to impair FMD. Conclusions: Brief SHS exposure at real-world levels reversibly impairs FMD. Even 1min of SHS exposure can cause reduction of endothelial function. PMID:24302638

  5. Beyond apoptosis: The mechanism and function of phosphatidylserine asymmetry in the membrane of activating mast cells

    PubMed Central

    Rysavy, Noel M.; Shimoda, Lori M. N.; Dixon, Alyssa M.; Speck, Mark; Stokes, Alexander J.; Turner, Helen; Umemoto, Eric Y.

    2014-01-01

    Loss of plasma membrane asymmetry is a hallmark of apoptosis, but lipid bilayer asymmetry and loss of asymmetry can contribute to numerous cellular functions and responses that are independent of programmed cell death. Exofacial exposure of phosphatidylserine occurs in lymphocytes and mast cells after antigenic stimulation and in the absence of apoptosis, suggesting that there is a functional requirement for phosphatidylserine exposure in immunocytes. In this review we examine current ideas as to the nature of this functional role in mast cell activation. Mechanistically, there is controversy as to the candidate proteins responsible for phosphatidylserine translocation from the internal to external leaflet, and here we review the candidacies of mast cell PLSCR1 and TMEM16F. Finally we examine the potential relationship between functionally important mast cell membrane perturbations and phosphatidylserine exposure during activation. PMID:25759911

  6. Association of reversible alopecia with occupational topical exposure to common borax-containing solutions.

    PubMed

    Beckett, W S; Oskvig, R; Gaynor, M E; Goldgeier, M H

    2001-04-01

    Boron is widely used in industrial materials, most frequently as the salt borax. Systemic exposure (eg, ingestion) to boron in boric acid been associated with reversible toxic alopecia among other manifestations. There is scant clinical literature on alopecia caused by topical exposure to boron. We observed a series of 3 patients in 2 workplaces who suffered reversible alopecia from cutaneous boron exposure. The scalp alopecia was global in 1 patient and patchy in 2 patients. Alopecia was completely reversed by elimination or reduction of exposure to boron-containing materials in all 3 patients. We conclude that occupational topical exposure to boron in solutions may cause reversible alopecia.

  7. Use of Autoantigen-Loaded Phosphatidylserine-Liposomes to Arrest Autoimmunity in Type 1 Diabetes

    PubMed Central

    Pujol-Autonell, Irma; Serracant-Prat, Arnau; Cano-Sarabia, Mary; Ampudia, Rosa M.; Rodriguez-Fernandez, Silvia; Sanchez, Alex; Izquierdo, Cristina; Stratmann, Thomas; Puig-Domingo, Manuel; Maspoch, Daniel; Verdaguer, Joan; Vives-Pi, Marta

    2015-01-01

    Introduction The development of new therapies to induce self-tolerance has been an important medical health challenge in type 1 diabetes. An ideal immunotherapy should inhibit the autoimmune attack, avoid systemic side effects and allow β-cell regeneration. Based on the immunomodulatory effects of apoptosis, we hypothesized that apoptotic mimicry can help to restore tolerance lost in autoimmune diabetes. Objective To generate a synthetic antigen-specific immunotherapy based on apoptosis features to specifically reestablish tolerance to β-cells in type 1 diabetes. Methods A central event on the surface of apoptotic cells is the exposure of phosphatidylserine, which provides the main signal for efferocytosis. Therefore, phosphatidylserine-liposomes loaded with insulin peptides were generated to simulate apoptotic cells recognition by antigen presenting cells. The effect of antigen-specific phosphatidylserine-liposomes in the reestablishment of peripheral tolerance was assessed in NOD mice, the spontaneous model of autoimmune diabetes. MHC class II-peptide tetramers were used to analyze the T cell specific response after treatment with phosphatidylserine-liposomes loaded with peptides. Results We have shown that phosphatidylserine-liposomes loaded with insulin peptides induce tolerogenic dendritic cells and impair autoreactive T cell proliferation. When administered to NOD mice, liposome signal was detected in the pancreas and draining lymph nodes. This immunotherapy arrests the autoimmune aggression, reduces the severity of insulitis and prevents type 1 diabetes by apoptotic mimicry. MHC class II tetramer analysis showed that peptide-loaded phosphatidylserine-liposomes expand antigen-specific CD4+ T cells in vivo. The administration of phosphatidylserine-free liposomes emphasizes the importance of phosphatidylserine in the modulation of antigen-specific CD4+ T cell expansion. Conclusions We conclude that this innovative immunotherapy based on the use of liposomes

  8. Leishmania amazonensis exhibits phosphatidylserine-dependent procoagulant activity, a process that is counteracted by sandfly saliva.

    PubMed

    Rochael, Natalia Cadaxo; Lima, Luize Gonçalves; Oliveira, Sandra Maria Pereira de; Barcinski, Marcello André; Saraiva, Elvira Maria; Monteiro, Robson Queiroz; Pinto-da-Silva, Lucia Helena

    2013-09-01

    Leishmania parasites expose phosphatidylserine (PS) on their surface, a process that has been associated with regulation of host's immune responses. In this study we demonstrate that PS exposure by metacyclic promastigotes of Leishmania amazonensis favours blood coagulation. L. amazonensis accelerates in vitro coagulation of human plasma. In addition, L. amazonensis supports the assembly of the prothrombinase complex, thus promoting thrombin formation. This process was reversed by annexin V which blocks PS binding sites. During blood meal, Lutzomyia longipalpis sandfly inject saliva in the bite site, which has a series of pharmacologically active compounds that inhibit blood coagulation. Since saliva and parasites are co-injected in the host during natural transmission, we evaluated the anticoagulant properties of sandfly saliva in counteracting the procoagulant activity of L. amazonensis . Lu. longipalpis saliva reverses plasma clotting promoted by promastigotes. It also inhibits thrombin formation by the prothrombinase complex assembled either in phosphatidylcholine (PC)/PS vesicles or in L. amazonensis . Sandfly saliva inhibits factor X activation by the intrinsic tenase complex assembled on PC/PS vesicles and blocks factor Xa catalytic activity. Altogether our results show that metacyclic promastigotes of L. amazonensis are procoagulant due to PS exposure. Notably, this effect is efficiently counteracted by sandfly saliva.

  9. PROcEED: Probabilistic reverse dosimetry approaches for estimating exposure distributions

    EPA Science Inventory

    As increasing amounts of biomonitoring survey data become available, a new discipline focused on converting such data into estimates of chemical exposures has developed. Reverse dosimetry uses a pharmacokinetic model along with measured biomarker concentrations to determine the p...

  10. Product-to-parent reversion processes: Stream-hyporheic spiraling increases ecosystem exposure and environmental persistence

    NASA Astrophysics Data System (ADS)

    Ward, A. S.; Cwiertny, D. M.; Kolodziej, E. P.

    2014-12-01

    The product-to-parent reversion of metabolites of trenbolone acetate (TBA), a steroidal growth promoter used widely in beef cattle production, was recently observed to occur in environmental waters. The rapid forward reaction is by direct photolysis (i.e., photohydration), with the much slower reversion reaction occurring via dehydration in the dark. The objective of this study is to quantify the potential effect of this newly discovered reversible process on TBA metabolite concentrations and total bioactivity exposure in fluvial systems. Here, we demonstrate increased persistence of TBA metabolites in the stream and hyporheic zone due to the reversion process, increasing chronic and acute exposure to these endocrine-active compounds along a stream. The perpetually dark hyporheic zone is a key location for reversion in the system, ultimately providing a source of the parent compound to the stream and increasing mean in-stream concentration of 17α-trenbolone (17α-TBOH) by 40% of the input concentration under representative fluvial conditions. As such, regulatory frameworks for compounds undergoing product-to-parent reversion will require new approaches for assessing total exposure to bioactive compounds. Further, we demonstrate generalized cases for prediction of exposure for species with product-to-parent reversion in stream-hyporheic systems.

  11. Phosphatidylserine in the brain: metabolism and function.

    PubMed

    Kim, Hee-Yong; Huang, Bill X; Spector, Arthur A

    2014-10-01

    Phosphatidylserine (PS) is the major anionic phospholipid class particularly enriched in the inner leaflet of the plasma membrane in neural tissues. PS is synthesized from phosphatidylcholine or phosphatidylethanolamine by exchanging the base head group with serine, and this reaction is catalyzed by phosphatidylserine synthase 1 and phosphatidylserine synthase 2 located in the endoplasmic reticulum. Activation of Akt, Raf-1 and protein kinase C signaling, which supports neuronal survival and differentiation, requires interaction of these proteins with PS localized in the cytoplasmic leaflet of the plasma membrane. Furthermore, neurotransmitter release by exocytosis and a number of synaptic receptors and proteins are modulated by PS present in the neuronal membranes. Brain is highly enriched with docosahexaenoic acid (DHA), and brain PS has a high DHA content. By promoting PS synthesis, DHA can uniquely expand the PS pool in neuronal membranes and thereby influence PS-dependent signaling and protein function. Ethanol decreases DHA-promoted PS synthesis and accumulation in neurons, which may contribute to the deleterious effects of ethanol intake. Improvement of some memory functions has been observed in cognitively impaired subjects as a result of PS supplementation, but the mechanism is unclear.

  12. Reversible Inactivation of the Auditory Thalamus Disrupts HPA Axis Habituation to Repeated Loud Noise Stress Exposures

    PubMed Central

    Day, Heidi E.W.; Masini, Cher V.; Campeau, Serge

    2009-01-01

    Although habituation to stress is a widely observed adaptive mechanism in response to repeated homotypic challenge exposure, its brain location and mechanism of plasticity remains elusive. And while habituation-related plasticity has been suggested to take place in central limbic regions, recent evidence suggests that sensory sites may provide the underlying substrate for this function. For instance, several brainstem, midbrain, thalamic, and/or cortical auditory processing areas, among others, could support habituation-related plasticity to repeated loud noise exposures. In the present study, the auditory thalamus was tested for its putative role in habituation to repeated loud noise exposures, in rats. The auditory thalamus was inactivated reversibly by muscimol injections during repeated loud noise exposures to determine if brainstem or midbrain auditory nuclei would be sufficient to support habituation to this specific stressor, as measured during an additional and drug-free loud noise exposure test. Our results indicate that auditory thalamic inactivation by muscimol disrupts acute HPA axis response specifically to loud noise. Importantly, habituation to repeated loud noise exposures was also prevented by reversible auditory thalamic inactivation, suggesting that this form of plasticity is likely mediated at, or in targets of, the auditory thalamus. PMID:19379718

  13. Bacterial bioluminescence response to long-term exposure to reverse osmosis treated effluents from dye industries.

    PubMed

    Ravindran, J; Manikandan, B; Shirodkar, P V; Francis, K X; Mani Murali, R; Vethamony, P

    2014-10-01

    The bacterial bioluminescence assay is one of the novel means for toxicity detection. The bioluminescence response of 2 marine bioluminescent bacteria was tested upon their long-term exposure to 9 different reverse osmosis (RO) rejects with varying chemical composition sampled from various dye industries. Bioluminescent bacteria were cultured in the RO reject samples, at different concentrations, and their growth rate and luminescence was measured for 24 h. The RO reject samples caused sublethal effects upon exposure and retarded the growth of bacteria, confirming their toxic nature. Further, continuation of the exposure showed that the initial luminescence, though reduced, recovered and increased beyond the control cultures irrespective of cell density, and finally decreased once again. The present study emphasizes the need of evolving a long-term exposure assay and shows that the method followed in this study is suitable to evaluate the toxicants that exert delayed toxicity, using lower concentrations of toxicants as well as coloured samples.

  14. Characterization of the phosphatidylserine-exposing subpopulation of sickle cells.

    PubMed

    de Jong, K; Larkin, S K; Styles, L A; Bookchin, R M; Kuypers, F A

    2001-08-01

    Phosphatidylserine (PS), exclusively present in the inner monolayer of the normal red blood cell (RBC) membrane, is exposed in subpopulations of sickle cells. PS-exposing RBCs were found predominantly among the densest and the very light sickle cells. Within the light RBC fraction, PS exposure was found on reticulocytes, transferrin receptor-expressing reticulocytes, and mature RBCs. The last subset contained low-density valinomycin-resistant RBCs, previously shown to have high Na(+) and low K(+) content. This subpopulation contained the highest percentage of PS-exposing cells. The PS-exposing sickle cells did not show the sustained high cytosolic Ca(++) levels that have been shown to activate scramblase activity. Data from this study indicate that PS exposure can occur at different stages in the life of the sickle RBC and that it correlates with the loss of aminophospholipid translocase activity, the only common denominator of the PS-exposing cells. The additional requirement of scramblase activation may occur during transient increases in cytosolic Ca(++). (Blood. 2001;98:860-867)

  15. Vascular dysfunction in patients with chronic arsenosis can be reversed by reduction of arsenic exposure.

    PubMed

    Pi, Jingbo; Yamauchi, Hiroshi; Sun, Guifan; Yoshida, Takahiko; Aikawa, Hiroyuki; Fujimoto, Wataru; Iso, Hiroyasu; Cui, Renzhe; Waalkes, Michael P; Kumagai, Yoshito

    2005-03-01

    Chronic arsenic exposure causes vascular diseases associated with systematic dysfunction of endogenous nitric oxide. Replacement of heavily arsenic-contaminated drinking water with low-arsenic water is a potential intervention strategy for arsenosis, although the reversibility of arsenic intoxication has not established. In the present study, we examined urinary excretion of cyclic guanosine 3 ,5 -monophosphate (cGMP), a second messenger of the vasoactive effects of nitric oxide, and signs and symptoms for peripheral vascular function in 54 arsenosis patients before and after they were supplied with low-arsenic drinking water in an endemic area of chronic arsenic poisoning in Inner Mongolia, China. The arsenosis patients showed a marked decrease in urinary excretion of cGMP (mean +/- SEM: male, 37.0 +/- 6.1; female, 37.2 +/- 5.4 nmol/mmol creatinine), and a 13-month period of consuming low-arsenic drinking water reversed this trend (male, 68.0 +/- 5.6; female, 70.6 +/- 3.0 nmol/mmol creatinine) and improved peripheral vascular response to cold stress. Our intervention study indicates that peripheral vascular disease in arsenosis patients can be reversed by exposure cessation and has important implications for the public health approach to arsenic exposure. PMID:15743725

  16. Vascular dysfunction in patients with chronic arsenosis can be reversed by reduction of arsenic exposure.

    PubMed

    Pi, Jingbo; Yamauchi, Hiroshi; Sun, Guifan; Yoshida, Takahiko; Aikawa, Hiroyuki; Fujimoto, Wataru; Iso, Hiroyasu; Cui, Renzhe; Waalkes, Michael P; Kumagai, Yoshito

    2005-03-01

    Chronic arsenic exposure causes vascular diseases associated with systematic dysfunction of endogenous nitric oxide. Replacement of heavily arsenic-contaminated drinking water with low-arsenic water is a potential intervention strategy for arsenosis, although the reversibility of arsenic intoxication has not established. In the present study, we examined urinary excretion of cyclic guanosine 3 ,5 -monophosphate (cGMP), a second messenger of the vasoactive effects of nitric oxide, and signs and symptoms for peripheral vascular function in 54 arsenosis patients before and after they were supplied with low-arsenic drinking water in an endemic area of chronic arsenic poisoning in Inner Mongolia, China. The arsenosis patients showed a marked decrease in urinary excretion of cGMP (mean +/- SEM: male, 37.0 +/- 6.1; female, 37.2 +/- 5.4 nmol/mmol creatinine), and a 13-month period of consuming low-arsenic drinking water reversed this trend (male, 68.0 +/- 5.6; female, 70.6 +/- 3.0 nmol/mmol creatinine) and improved peripheral vascular response to cold stress. Our intervention study indicates that peripheral vascular disease in arsenosis patients can be reversed by exposure cessation and has important implications for the public health approach to arsenic exposure.

  17. Phosphatidylserine receptors: enhancers of enveloped virus entry and infection

    PubMed Central

    Moller-Tank, Sven; Maury, Wendy

    2014-01-01

    A variety of both RNA and DNA viruses envelop their capsids in a lipid bilayer. One of the more recently appreciated benefits this envelope is incorporation of phosphatidylserine (PtdSer). Surface exposure of PtdSer disguises viruses as apoptotic bodies; tricking cells into engulfing virions. This mechanism is termed apoptotic mimicry. Several PtdSer receptors have been identified to enhance virus entry and we have termed this group of proteins PtdSer-mediated virus entry enhancing receptors or PVEERs. These receptors enhance entry of a broad range of enveloped viruses. Internalization of virions by PVEERs provides a broad mechanism of entry with little investment by the virus itself and may allow some viruses to attach to cells, thereby making viral glycoprotein/cellular receptor interactions more probable. Alternatively, other viruses may rely entirely on PVEERs for internalization into endosomes. This review provides an overview of PtdSer receptors that serve as PVEERs and the biology behind virion/PVEER interaction. PMID:25277499

  18. Elevated Human telomerase reverse transcriptase gene expression in blood cells associated with chronic and arsenic exposure in Inner Mongolia, China

    EPA Science Inventory

    BACKGROUND: Arsenic exposure is associated with human cancer. Telomerase containing the catalytic subunit, human telomerase reverse transcriptase (hTERT), can extend telomeres of chromosomes, delay senescence and promoting cell proliferation leading to tumorigenesis. OBJECTIVE:...

  19. Phosphatidylserine: an antidepressive or a cognitive enhancer?

    PubMed

    Castilho, João C; Perry, Juliana C; Andreatini, Roberto; Vital, Maria A B F

    2004-07-01

    The aim of the present study was to evaluate the putative antidepressive and cognitive enhancer effects of phosphatidylserine (BC-PS). The antidepressive effect of BC-PS (50, 100 or 200 mg/kg), compared to saline or imipramine (IMI; 25 mg/kg), was studied in the forced swimming test in rats. These drugs were administered 1 and 8 h after training and 1 h before the test. BC-PS (50, 100 and 200 mg/kg)-treated rats exhibited a significant decrease in immobility time (IT) in the test session (performed 24 h after training) when compared to control rats. Moreover, the IMI-treated group showed a significant reduction in IT in comparison to control rats. The cognitive enhancer effect of BC-PS (50, 100 and 200 mg/kg) was studied in the three versions of the water maze task: spatial working memory version, spatial reference memory version, and cued version. There was no significant difference between the BC-PS-treated groups and control animals in these memory tasks. Taken together, the present results are suggestive of an antidepressive effect of BC-PS in the forced swimming test in rats but not of a cognitive enhancer effect of the drug in the water maze test.

  20. Reversals.

    ERIC Educational Resources Information Center

    National Center on Educational Media and Materials for the Handicapped, Columbus, OH.

    Selected from the National Instructional Materials Information System (NIMIS)--a computer based on-line interactive retrieval system on special education materials--the bibliography covers nine materials for remediating reversals in handicapped students at the early childhood and elementary levels. Entries are presented in order of NIMIS accession…

  1. Behavioural treatment of tics: habit reversal and exposure with response prevention.

    PubMed

    van de Griendt, J M T M; Verdellen, C W J; van Dijk, M K; Verbraak, M J P M

    2013-07-01

    Behaviour therapy has been shown to be an effective strategy in treating tics; both habit reversal (HR) and exposure and response prevention (ER) are recommended as first-line interventions. This review provides an overview of the history, theoretical concepts and evidence at present for HR and ER. In addition, treatment manuals for HR and ER are described. Despite the evidence and availability of treatment manuals, many patients do not receive a first-line psychological intervention for tics. Barriers to the acceptance and dissemination of behaviour therapy are discussed as are ways to overcome these barriers, such as the use of E-health and E-learning.

  2. Thymosin α1 Interacts with Exposed Phosphatidylserine in Membrane Models and in Cells and Uses Serum Albumin as a Carrier.

    PubMed

    Mandaliti, Walter; Nepravishta, Ridvan; Sinibaldi Vallebona, Paola; Pica, Francesca; Garaci, Enrico; Paci, Maurizio

    2016-03-15

    Thymosin α1 is a peptidic hormone with pleiotropic activity and is used in the therapy of several diseases. It is unstructured in water solution and interacts with negative regions of vesicles by assuming two tracts of helical conformation with a structural break between them. This study reports on Thymosin α1's interaction with mixed phospholipids phosphatidylcholine and phosphatidylserine, the negative component of the membranes, by ¹H and natural abundance ¹⁵N nuclear magnetic resonance (NMR). The results indicate that interaction occurs when the membrane is negatively charged by exposing phosphatidylserine. Moreover, the direct interaction of Thymosin α1 with K562 cells with an overexposure of phosphatidylserine as a consequence of resveratrol-induced apoptosis was conducted. Thymosin α1's interaction with human serum albumin was also investigated by NMR spectroscopy. Steady-state saturation transfer, transfer nuclear Overhauser effect spectroscopy, and diffusion-ordered spectroscopy methodologies all reveal that the C-terminal region of Thymosin α1 is involved in the interaction with serum albumin. These results may shed more light on Thymosin α1's mechanism of action by its insertion in negative regions of membranes due to the exposure of phosphatidylserine. Once Thymosin α1's N-terminus has been inserted into the membrane, the rest may interact with nearby proteins and/or receptors acting as effectors and causing a biological signaling cascade, thus exerting thymosin α1's pleiotropy. PMID:26909491

  3. Reversible suppression of protein synthesis in concert with polysome disaggregation during anoxia exposure in Littorina littorea.

    PubMed

    Larade, Kevin; Storey, Kenneth B

    2002-03-01

    Many marine invertebrates can live without oxygen for long periods of time, a capacity that is facilitated by the ability to suppress metabolic rate in anoxia to a value that is typically less than 10% of the normal aerobic rate. The present study demonstrates that a reduction in the rate of protein synthesis is one factor in the overall anoxia-induced metabolic suppression in the marine snail, Littorina littorea. The rate of [3H]leucine incorporation into newly translated protein in hepatopancreas isolated from 48 h anoxic snails was determined to be 49% relative to normoxic controls. However, protein concentration in hepatopancreas did not change during anoxia, suggesting a coordinated suppression of net protein turnover. Analysis of hepatopancreas samples from snails exposed to 24-72 h anoxia showed a gradual disaggregation of polysomes into monosomes. A re-aggregation of monosomes into polysomes was observed after 3 h of aerobic recovery. Analysis of fractions from the ribosome profile using radiolabeled probe to detect alpha-tubulin transcripts confirmed a general decrease in protein translation during anoxia exposure (transcript association with polysomes decreased) with a reversal during aerobic recovery. Western blotting of hepatopancreas samples from normoxic, 24 h anoxic, and 1 h aerobic recovered snails demonstrated that eIF-2alpha is substantially phosphorylated during anoxia exposure and dephosphorylated during normoxia and aerobic recovery, suggesting a decrease in translation initiation during anoxia exposure. These results suggest that metabolic suppression during anoxia exposure in L. littorea involves a decrease in protein translation. PMID:12030368

  4. Product-to-parent reversion increases ecosystem exposure to and environmental persistence of 17α-trenbolone

    NASA Astrophysics Data System (ADS)

    Ward, Adam; Cwiertny, David; Kolodziej, Edward; Brehm, Colleen

    2016-04-01

    The product-to-parent reversion of metabolites of trenbolone acetate (TBA), a steroidal growth promoter used widely in beef cattle production, was recently observed to occur in environmental waters. The rapid forward reaction is by direct photolysis (i.e., photohydration), with the much slower reversion reaction occurring via dehydration in the dark. The objective of this study is to quantify the potential effect of this newly discovered reversible process on TBA metabolite concentrations and total bioactivity exposure in fluvial systems. Here, we demonstrate increased persistence of TBA metabolites in the stream and hyporheic zone due to the reversion process, increasing chronic and acute exposure to these endocrine-active compounds along a stream. The perpetually dark hyporheic zone is a key location for reversion in the system, ultimately providing a source of the parent compound to the stream and increasing mean in-stream concentration of 17α-trenbolone (17α‑TBOH) by 40% of the input concentration under representative fluvial conditions. We demonstrate generalized cases for prediction of exposure for species with product-to-parent reversion in stream-hyporheic systems. Recognizing this risk, regulatory frameworks for compounds undergoing product-to-parent reversion will require new approaches for assessing total exposure to bioactive compounds. We discuss the role of regulating "joint" or "mixture" bioactivity as an emerging paradigm for more meaningful management of micropollutants.

  5. Product-to-parent reversion increases ecosystem exposure to and environmental persistence of 17α-trenbolone

    NASA Astrophysics Data System (ADS)

    Ward, Adam; Cwiertny, David; Kolodziej, Edward; Brehm, Colleen

    2016-04-01

    The product-to-parent reversion of metabolites of trenbolone acetate (TBA), a steroidal growth promoter used widely in beef cattle production, was recently observed to occur in environmental waters. The rapid forward reaction is by direct photolysis (i.e., photohydration), with the much slower reversion reaction occurring via dehydration in the dark. The objective of this study is to quantify the potential effect of this newly discovered reversible process on TBA metabolite concentrations and total bioactivity exposure in fluvial systems. Here, we demonstrate increased persistence of TBA metabolites in the stream and hyporheic zone due to the reversion process, increasing chronic and acute exposure to these endocrine-active compounds along a stream. The perpetually dark hyporheic zone is a key location for reversion in the system, ultimately providing a source of the parent compound to the stream and increasing mean in-stream concentration of 17α-trenbolone (17α-TBOH) by 40% of the input concentration under representative fluvial conditions. We demonstrate generalized cases for prediction of exposure for species with product-to-parent reversion in stream-hyporheic systems. Recognizing this risk, regulatory frameworks for compounds undergoing product-to-parent reversion will require new approaches for assessing total exposure to bioactive compounds. We discuss the role of regulating "joint" or "mixture" bioactivity as an emerging paradigm for more meaningful management of micropollutants.

  6. Behavioral training reverses global cortical network dysfunction induced by perinatal antidepressant exposure

    PubMed Central

    Zhou, Xiaoming; Lu, Jordan Y.-F.; Darling, Ryan D.; Simpson, Kimberly L.; Zhu, Xiaoqing; Wang, Fang; Yu, Liping; Sun, Xinde; Merzenich, Michael M.; Lin, Rick C. S.

    2015-01-01

    Abnormal cortical circuitry and function as well as distortions in the modulatory neurological processes controlling cortical plasticity have been argued to underlie the origin of autism. Here, we chemically distorted those processes using an antidepressant drug-exposure model to generate developmental neurological distortions like those characteristics expressed in autism, and then intensively trained altered young rodents to evaluate the potential for neuroplasticity-driven renormalization. We found that young rats that were injected s.c. with the antidepressant citalopram from postnatal d 1–10 displayed impaired neuronal repetition-rate following capacity in the primary auditory cortex (A1). With a focus on recovering grossly degraded auditory system processing in this model, we showed that targeted temporal processing deficits induced by early-life antidepressant exposure within the A1 were almost completely reversed through implementation of a simple behavioral training strategy (i.e., a modified go/no-go repetition-rate discrimination task). Degraded parvalbumin inhibitory GABAergic neurons and the fast inhibitory actions that they control were also renormalized by training. Importantly, antidepressant-induced degradation of serotonergic and dopaminergic neuromodulatory systems regulating cortical neuroplasticity was sharply reversed. These findings bear important implications for neuroplasticity-based therapeutics in autistic patients. PMID:25646455

  7. Glutamate NMDA receptor antagonists rapidly reverse behavioral and synaptic deficits caused by chronic stress exposure

    PubMed Central

    Li, Nanxin; Liu, Rong-Jian; Dwyer, Jason M.; Banasr, Mounira; Lee, Boyoung; Son, Hyeon; Li, Xiao-Yuan; Aghajanian, George; Duman, Ronald S.

    2011-01-01

    Background Despite widely reported clinical and preclinical studies of rapid antidepressant actions of glutamate N-methyl-D-aspartic acid (NMDA) receptor antagonists, there has been very little work examining the effects of these drugs in stress models of depression that require chronic administration of antidepressants, or the molecular mechanisms that could account for the rapid responses. Methods We used a rat 21-day chronic unpredictable stress (CUS) model to test the rapid actions of NMDA receptor antagonists on depressant-like behavior, neurochemistry, and spine density and synaptic function of prefrontal cortex (PFC) neurons. Results The results demonstrate that acute treatment with the non-competitive NMDA channel blocker ketamine or the selective NR2B antagonist Ro 25-6981 rapidly ameliorates CUS-induced anhedonia and anxiogenic behaviors. We also find that CUS exposure decreases the expression levels of synaptic proteins and spine number and the frequency/amplitude of synaptic currents (EPSCs) in layer V pyramidal neurons in the PFC, and that these deficits are rapidly reversed by ketamine. Blockade of the mammalian target of rapamycin (mTOR) protein synthesis cascade abolishes both the behavioral and biochemical effects of ketamine. Conclusions The results indicate that the structural and functional deficits resulting from long-term stress exposure, which could contribute to the pathophysiology of depression, are rapidly reversed by NMDA receptor antagonists in an mTOR-dependent manner. PMID:21292242

  8. Localization, Purification, and Functional Reconstitution of the P4-ATPase Atp8a2, a Phosphatidylserine Flippase in Photoreceptor Disc Membranes*

    PubMed Central

    Coleman, Jonathan A.; Kwok, Michael C. M.; Molday, Robert S.

    2009-01-01

    P4-ATPases comprise a relatively new subfamily of P-type ATPases implicated in the energy-dependent translocation of aminophospholipids across cell membranes. In this study, we report on the localization and functional properties of Atp8a2, a member of the P4-ATPase subfamily that has not been studied previously. Reverse transcription-PCR revealed high expression of atp8a2 mRNA in the retina and testis. Within the retina, immunofluorescence microscopy and subcellular fractionation studies localized Atp8a2 to outer segment disc membranes of rod and cone photoreceptor cells. Atp8a2 purified from photoreceptor outer segments by immunoaffinity chromatography exhibited ATPase activity that was stimulated by phosphatidylserine and to a lesser degree phosphatidylethanolamine but not by phosphatidylcholine or other membrane lipids. Purified Atp8a2 was reconstituted into liposomes containing fluorescent-labeled phosphatidylserine to measure the ability of Atp8a2 to flip phosphatidylserine across the lipid bilayer. Fluorescence measurements showed that Atp8a2 flipped fluorescent-labeled phosphatidylserine from the inner leaflet of liposomes (equivalent to the exocytoplasmic leaflet of cell membranes) to the outer leaflet (equivalent to cytoplasmic leaflet) in an ATP-dependent manner. Our studies provide the first direct biochemical evidence that purified P4-ATPases can translocate aminophospholipids across membranes and further implicates Atp8a2 in the generation and maintenance of phosphatidylserine asymmetry in photoreceptor disc membranes. PMID:19778899

  9. Reversibility of endocrine disruption in zebrafish (Danio rerio) after discontinued exposure to the estrogen 17α-ethinylestradiol.

    PubMed

    Baumann, Lisa; Knörr, Susanne; Keiter, Susanne; Rehberger, Kristina; Volz, Sina; Schiller, Viktoria; Fenske, Martina; Holbech, Henrik; Segner, Helmut; Braunbeck, Thomas

    2014-08-01

    The aim of the present study was to investigate the persistence of the feminizing effects of discontinued 17α-ethinylestradiol (EE2) exposure on zebrafish (Danio rerio). An exposure scenario covering the sensitive phase of sexual differentiation, as well as final gonad maturation was chosen to examine the estrogenic effects on sexual development of zebrafish. Two exposure scenarios were compared: continuous exposure to environmentally relevant concentrations (0.1-10 ng/L EE2) up to 100 days post-hatch (dph) and developmental exposure up to 60 dph, followed by 40 days of depuration in clean water. The persistence of effects was investigated at different biological organization levels from mRNA to population-relevant endpoints to cover a broad range of important parameters. EE2 had a strong feminizing and inhibiting effect on the sexual development of zebrafish. Brain aromatase (cyp19b) mRNA expression showed no clear response, but vitellogenin levels were significantly elevated, gonad maturation and body growth were inhibited in both genders, and sex ratios were skewed towards females and undifferentiated individuals. To a large extent, all of these effects were reversed after 40 days of recovery, leading to the conclusion that exposure to the estrogen EE2 results in very strong, but reversible underdevelopment and feminization of zebrafish. The present study is the first to show this reversibility at different levels of organization, which gives better insight into the mechanistic basis of estrogenic effects in zebrafish. PMID:24832493

  10. Plaque-media rewelding with reversible tissue optical property changes during receptive cw Nd:YAG laser exposure.

    PubMed

    Spears, J R; James, L M; Leonard, B M; Sinclair, I N; Jenkins, R D; Motamedi, M; Sinofsky, E L

    1988-01-01

    Laser dosimetry for thermal fusion of plaque-wall separations during laser balloon angioplasty (LBA) is dependent upon the optical properties of the atheromatous arterial wall during one or more exposures to cw Nd:YAG laser radiation. An integrating sphere technique was used to measure relative transmission and reflection continuously during irradiation of human postmortem atheromatous aortic sections. Tissue luminal surface temperature was recorded continuously with a thermographic video imager during repetitive 20-30-sec, 8-15-watt exposure of a 3-mm nominal spot. In all specimens, transmission fell progressively during each exposure by 10-70% of baseline values. This effect was reversible with normalization of transmission during the initial phase of each subsequent exposure. Changes in transmission were inversely related to temperature over a 50-170 degrees C range, whereas relative reflection remained constant. Accompanying reversible transmission changes was the observation that the weld strength of plaque-aortic wall separations was unchanged by repetitive laser welding and tissue separation of individual sections. In conclusion, temperature-dependent reversible optical and physical properties of plaque occur during exposure to 1.06 microns cw laser radiation. PMID:2976446

  11. Maternal obesity caused by overnutrition exposure leads to reversal learning deficits and striatal disturbance in rats.

    PubMed

    Wu, Ting; Deng, Shining; Li, Wei-Guang; Yu, Yongguo; Li, Fei; Mao, Meng

    2013-01-01

    Maternal obesity caused by overnutrition during pregnancy increases susceptibility to metabolic risks in adulthood, such as obesity, insulin resistance, and type 2 diabetes; however, whether and how it affects the cognitive system associated with the brain remains elusive. Here, we report that pregnant obesity induced by exposure to excessive high fatty or highly palatable food specifically impaired reversal learning, a kind of adaptive behavior, while leaving serum metabolic metrics intact in the offspring of rats, suggesting a much earlier functional and structural defects possibly occurred in the central nervous system than in the metabolic system in the offspring born in unfavorable intrauterine nutritional environment. Mechanically, we found that above mentioned cognitive inflexibility might be associated with significant striatal disturbance including impaired dopamine homeostasis and disrupted leptin signaling in the adult offspring. These collective data add a novel perspective of understanding the adverse postnatal sequelae in central nervous system induced by developmental programming and the related molecular mechanism through which priming of risk for developmental disorders may occur during early life. PMID:24223863

  12. Maternal Obesity Caused by Overnutrition Exposure Leads to Reversal Learning Deficits and Striatal Disturbance in Rats

    PubMed Central

    Wu, Ting; Deng, Shining; Li, Wei-Guang; Yu, Yongguo; Li, Fei; Mao, Meng

    2013-01-01

    Maternal obesity caused by overnutrition during pregnancy increases susceptibility to metabolic risks in adulthood, such as obesity, insulin resistance, and type 2 diabetes; however, whether and how it affects the cognitive system associated with the brain remains elusive. Here, we report that pregnant obesity induced by exposure to excessive high fatty or highly palatable food specifically impaired reversal learning, a kind of adaptive behavior, while leaving serum metabolic metrics intact in the offspring of rats, suggesting a much earlier functional and structural defects possibly occurred in the central nervous system than in the metabolic system in the offspring born in unfavorable intrauterine nutritional environment. Mechanically, we found that above mentioned cognitive inflexibility might be associated with significant striatal disturbance including impaired dopamine homeostasis and disrupted leptin signaling in the adult offspring. These collective data add a novel perspective of understanding the adverse postnatal sequelae in central nervous system induced by developmental programming and the related molecular mechanism through which priming of risk for developmental disorders may occur during early life. PMID:24223863

  13. Lactation-induced reduction in hippocampal neurogenesis is reversed by repeated stress exposure.

    PubMed

    Hillerer, Katharina M; Neumann, Inga D; Couillard-Despres, Sebastien; Aigner, Ludwig; Slattery, David A

    2014-06-01

    The peripartum period is a time of high susceptibility for mood and anxiety disorders, some of which have recently been associated with alterations in hippocampal neurogenesis. Several factors including stress, aging, and, perhaps unexpectedly, lactation have been shown to decrease hippocampal neurogenesis. Intriguingly, lactation is also a time of reduced stress responsivity suggesting that the effect of stress on neurogenic processes may differ during this period. Therefore, the aim of the present study was to assess the effect of repeated stress during lactation [2 h restraint stress from lactation day (LD) 2 to LD13] on brain weight, hippocampal volume, cell proliferation and survival, and on neuronal and astroglial differentiation. In addition to confirming the known lactation-associated decrease in cell proliferation and survival, we could reveal that stress reversed the lactation-induced decrease in cell proliferation, while it did not affect survival of newly born cells, nor the number of mature neurons , nor did it alter immature neuron production or the number of astroglial cells in lactation. Stress exposure increased relative brain weight and hippocampal volume mirroring the observed changes in neurogenesis. Interestingly, hippocampal volume and relative brain weight were lower in lactation as compared to nulliparous females under nonstressed conditions. This study assessed the effect of stress during lactation on hippocampal neurogenesis and indicates that stress interferes with important peripartum adaptations at the level of the hippocampus.

  14. Paint thinner exposure inhibits testosterone synthesis and secretion in a reversible manner in the rat.

    PubMed

    Yilmaz, Bayram; Canpolat, Sinan; Sandal, Suleyman; Akpolat, Nusret; Kutlu, Selim; Ilhan, Necip; Kelestimur, Haluk

    2006-11-01

    Occupational exposure and sniffing of toluene-based organic solvents is an important public health problem. In this study, we have investigated the effects of paint thinner inhalation on testosterone synthesis and secretion in the male rat. A control group inhaled normal air ventilation. The remaining animals were divided into three groups and exposed to paint thinner in a glassy cage for 15 and 30 days (2 h/day). A group of rats was allowed to recover for 15 days after 30 days of exposure. Toluene concentration (the largest constituent in thinner, 66%) was set at 1500 ppm in the inhaled air. At the end, all animals were decapitated and blood samples obtained. Testes and seminal vesicles were removed and weighed out. Serum total testosterone levels were determined by chemiluminescence enzyme immunoassay. Testicular tissue specimens were processed for semi-quantitative evaluation of immunohistochemical testosterone staining and light microscopy. Intensity of immunostaining was evaluated on a scale between 0 (no staining), 1 (minimal), 2 (mild), 3 (moderate) and 4 (strong staining). Serum testosterone levels (ng/ml) were decreased by 15-day (3.31+/-0.61) and 30-day (1.17+/-0.54, p<0.02) thinner exposure compared to the controls (3.91+/-1.03). Another group of rats exposed to thinner for 30 days and then allowed to recover for a period of 15 days had significantly elevated levels of testosterone values (3.77+/-1.1; p<0.05). Immunohistochemical testosterone staining of the cytoplasm of Leydig cells was moderate (3+) and mild (2+) in 15 and 30 days thinner inhalation groups, respectively. Strong staining (4+) was restored following the recovery period. Testicular weight was significantly reduced in all test groups compared to the control values (p<0.01). Diameters of seminiferous tubules were significantly decreased in the solvent exposed groups with enlarged connective tissue. The present findings suggest that paint thinner inhalation inhibits testosterone synthesis

  15. Reversibility of endocrine disruption in zebrafish (Danio rerio) after discontinued exposure to the estrogen 17α-ethinylestradiol

    SciTech Connect

    Baumann, Lisa; Knörr, Susanne; Keiter, Susanne; Rehberger, Kristina; Volz, Sina; Schiller, Viktoria; Fenske, Martina; Holbech, Henrik; Segner, Helmut; Braunbeck, Thomas

    2014-08-01

    The aim of the present study was to investigate the persistence of the feminizing effects of discontinued 17α-ethinylestradiol (EE2) exposure on zebrafish (Danio rerio). An exposure scenario covering the sensitive phase of sexual differentiation, as well as final gonad maturation was chosen to examine the estrogenic effects on sexual development of zebrafish. Two exposure scenarios were compared: continuous exposure to environmentally relevant concentrations (0.1–10 ng/L EE2) up to 100 days post-hatch (dph) and developmental exposure up to 60 dph, followed by 40 days of depuration in clean water. The persistence of effects was investigated at different biological organization levels from mRNA to population-relevant endpoints to cover a broad range of important parameters. EE2 had a strong feminizing and inhibiting effect on the sexual development of zebrafish. Brain aromatase (cyp19b) mRNA expression showed no clear response, but vitellogenin levels were significantly elevated, gonad maturation and body growth were inhibited in both genders, and sex ratios were skewed towards females and undifferentiated individuals. To a large extent, all of these effects were reversed after 40 days of recovery, leading to the conclusion that exposure to the estrogen EE2 results in very strong, but reversible underdevelopment and feminization of zebrafish. The present study is the first to show this reversibility at different levels of organization, which gives better insight into the mechanistic basis of estrogenic effects in zebrafish. - Highlights: • Zebrafish were exposed to 17α-ethinylestradiol during their sexual differentiation. • Reversibility of effects was investigated after depuration of 40 days. • Morphological and physiological parameters were compared. • Zebrafish were able to recover at all different levels from mRNA to population.

  16. Reactive oxygen species and phosphatidylserine externalization in murine sickle red cells.

    PubMed

    Banerjee, Tinku; Kuypers, Frans A

    2004-02-01

    Due to their role in oxygen transport and the presence of redox active haemoglobin molecules, red blood cells (RBC) generate relatively high levels of reactive oxygen species (ROS). To counteract the potential deleterious effects of ROS, RBCs have a well-integrated network of anti-oxidant mechanisms to combat this oxidative stress. ROS formation is increased in sickle-cell disease (SCD) and our studies in a murine SCD model showed a significant increase in the generation of ROS when compared with normal mice. Our data also indicated that murine sickle RBCs exhibit a significantly increased ATP catabolism, partly due to the increased activity of glucose-6-phosphate dehydrogenase and glutathione reductase to regenerate intracellular glutathione (GSH) levels to neutralize the adverse milieu of oxidative stress. Higher ATP consumption by the murine sickle RBCs, together with the increased ROS formation and impairment of the aminophospholipid translocase or flipase may underlie the exposure of phosphatidylserine on the surface of these cells.

  17. Cooperative binding of Annexin A5 to phosphatidylserine on apoptotic cell membranes

    NASA Astrophysics Data System (ADS)

    Janko, Christina; Jeremic, Ivica; Biermann, Mona; Chaurio, Ricardo; Schorn, Christine; Muñoz, Luis E.; Herrmann, Martin

    2013-12-01

    Healthy cells exhibit an asymmetric plasma membrane with phosphatidylserine (PS) located on the cytoplasmic leaflet of the plasma membrane bilayer. Annexin A5-FITC, a PS binding protein, is commonly used to evaluate apoptosis in flow cytometry. PS exposed by apoptotic cells serves as a major ‘eat-me’ signal for phagocytes. Although exposition of PS has been observed after alternative stimuli, no clearance of viable, PS exposing cells has been detected. Thus, besides PS exposure, membranes of viable and apoptotic cells might exhibit specific characteristics. Here, we show that Annexin A5 binds in a cooperative manner to different types of dead cells. Shrunken apoptotic cells thereby showed the highest Hill coefficient values. Contrarily, parafomaldehyde fixation of apoptotic cells completely abrogates the cooperativity effect seen with dead and dying cells. We tend to speculate that the cooperative binding of Annexin A5 to the membranes of apoptotic cells reflects higher fluidity of the exposed membranes facilitating PS clustering.

  18. The Effects of Synthetic Estrogen Exposure on the Sexually Dimorphic Liver Transcriptome of the Sex-Role-Reversed Gulf Pipefish

    PubMed Central

    Rose, Emily; Flanagan, Sarah P.; Jones, Adam G.

    2015-01-01

    Species exhibiting sex-role reversal provide an unusual perspective on the evolution of sex roles and sex differences. However, the proximate effects of sex-role reversal are largely unknown. Endocrine disruptors provide an experimental mechanism to address hormonal regulation of sexually dimorphic gene expression in sex-role-reversed taxa. Here, we investigate gene expression patterns in the liver of the sex-role-reversed Gulf pipefish, because the liver is known to be sexually dimorphic and estrogen-regulated in species with conventional sex roles. Using next-generation RNA-sequencing technology (RNA-seq), we detected sexually dimorphic hepatic gene expression patterns, with a total of 482 differentially expressed genes between the sexes in Gulf pipefish. Two-thirds of these genes were over-expressed in females, and the sex-specific transcriptomes of this sex-role-reversed pipefish’s liver were superficially similar to those of fishes with conventional sex-roles. We exposed females, pregnant males, and non-pregnant males to 17α-ethinylestradiol (EE2) at ecologically relevant concentrations of 5ng/L and compared gene expression patterns in the livers of exposed fish to control fish. Several genes that were up-regulated in EE2-exposed males relative to control males were also found to be female-biased in control animals. These genes included several of the classic estrogen biomarkers, such as vitellogenin, choriogenin, and zona pellucida. Thus, estrogen exposure induced feminization of the male liver transcriptome in a sex-role-reversed pipefish. These results suggest that the ancestral state of estrogen-regulated female reproductive physiology has been retained in all sex-role-reversed vertebrates thus far studied, despite substantial evolution of the hormonal regulation of ornamentation and mating behavior in these interesting taxa. PMID:26448558

  19. Variation in human cancer cell external phosphatidylserine is regulated by flippase activity and intracellular calcium

    PubMed Central

    Vallabhapurapu, Subrahmanya D.; Blanco, Víctor M.; Sulaiman, Mahaboob K.; Vallabhapurapu, Swarajya Lakshmi; Chu, Zhengtao; Franco, Robert S.; Qi, Xiaoyang

    2015-01-01

    Viable cancer cells expose elevated levels of phosphatidylserine (PS) on the exoplasmic face of the plasma membrane. However, the mechanisms leading to elevated PS exposure in viable cancer cells have not been defined. We previously showed that externalized PS may be used to monitor, target and kill tumor cells. In addition, PS on tumor cells is recognized by macrophages and has implications in antitumor immunity. Therefore, it is important to understand the molecular details of PS exposure on cancer cells in order to improve therapeutic targeting. Here we explored the mechanisms regulating the surface PS exposure in human cancer cells and found that differential flippase activity and intracellular calcium are the major regulators of surface PS exposure in viable human cancer cells. In general, cancer cell lines with high surface PS exhibited low flippase activity and high intracellular calcium, whereas cancer cells with low surface PS exhibited high flippase activity and low intracellular calcium. High surface PS cancer cells also had higher total cellular PS than low surface PS cells. Together, our results indicate that the amount of external PS in cancer cells is regulated by calcium dependent flippase activity and may also be influenced by total cellular PS. PMID:26462157

  20. Antibodies to phosphatidylserine/prothrombin complex and the antiphospholipid syndrome.

    PubMed

    Sciascia, S; Bertolaccini, M L

    2014-10-01

    Antibodies to prothrombin can be detected by ELISA using prothrombin coated onto irradiated plates (aPT) or the phosphatidylserine/prothrombin complex as antigen (aPS/PT) and they have been both related with the clinical manifestation of APS. Current evidence supports the concept that they belong to distinct populations of autoantibodies. Nevertheless, they can both be detected simultaneously in one patient. This mini-review will focus on data available on aPS/PT antibodies and their clinical utility in the diagnosis of APS. PMID:25228735

  1. Host Cell Plasma Membrane Phosphatidylserine Regulates the Assembly and Budding of Ebola Virus

    PubMed Central

    Adu-Gyamfi, Emmanuel; Johnson, Kristen A.; Fraser, Mark E.; Scott, Jordan L.; Soni, Smita P.; Jones, Keaton R.; Digman, Michelle A.; Gratton, Enrico; Tessier, Charles R.

    2015-01-01

    ABSTRACT Lipid-enveloped viruses replicate and bud from the host cell where they acquire their lipid coat. Ebola virus, which buds from the plasma membrane of the host cell, causes viral hemorrhagic fever and has a high fatality rate. To date, little has been known about how budding and egress of Ebola virus are mediated at the plasma membrane. We have found that the lipid phosphatidylserine (PS) regulates the assembly of Ebola virus matrix protein VP40. VP40 binds PS-containing membranes with nanomolar affinity, and binding of PS regulates VP40 localization and oligomerization on the plasma membrane inner leaflet. Further, alteration of PS levels in mammalian cells inhibits assembly and egress of VP40. Notably, interactions of VP40 with the plasma membrane induced exposure of PS on the outer leaflet of the plasma membrane at sites of egress, whereas PS is typically found only on the inner leaflet. Taking the data together, we present a model accounting for the role of plasma membrane PS in assembly of Ebola virus-like particles. IMPORTANCE The lipid-enveloped Ebola virus causes severe infection with a high mortality rate and currently lacks FDA-approved therapeutics or vaccines. Ebola virus harbors just seven genes in its genome, and there is a critical requirement for acquisition of its lipid envelope from the plasma membrane of the human cell that it infects during the replication process. There is, however, a dearth of information available on the required contents of this envelope for egress and subsequent attachment and entry. Here we demonstrate that plasma membrane phosphatidylserine is critical for Ebola virus budding from the host cell plasma membrane. This report, to our knowledge, is the first to highlight the role of lipids in human cell membranes in the Ebola virus replication cycle and draws a clear link between selective binding and transport of a lipid across the membrane of the human cell and use of that lipid for subsequent viral entry. PMID

  2. Reversed C-arm projection for reduction of focal skin radiation exposure: experimental analysis and first clinical experience.

    PubMed

    Yokoi, Kensuke; Sumitsuji, Satoru; Kaneda, Hideaki; Siegrist, Patrick T; Tachibana, Koichi; Nanto, Shinsuke

    2014-04-01

    Radiodermatitis, predominantly over the right scapula, is a well-known complication of complex percutaneous coronary interventions (PCI). To reduce focal radiation exposure, we analyzed an inversed X-ray beam direction using a reversed C-arm position. On phantom experiment, we found that 130° right anterior oblique projection reduced skin dose over the right scapula by 98.2 % (P < 0.001) compared with conventional 50° left anterior oblique projection. A 73-year-old man with history of bypass surgery, multiple PCI and chronic radiodermatitis over the right scapula presented with recurrent chest pain. After successful PCI using the reversed C-arm projection, no aggravation of radiodermatitis was found.

  3. The linoleic acid derivative DCP-LA selectively activates PKC-epsilon, possibly binding to the phosphatidylserine binding site.

    PubMed

    Kanno, Takeshi; Yamamoto, Hideyuki; Yaguchi, Takahiro; Hi, Rika; Mukasa, Takeshi; Fujikawa, Hirokazu; Nagata, Tetsu; Yamamoto, Satoshi; Tanaka, Akito; Nishizaki, Tomoyuki

    2006-06-01

    This study examined the effect of 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA), a newly synthesized linoleic acid derivative with cyclopropane rings instead of cis-double bonds, on protein kinase C (PKC) activity. In the in situ PKC assay with reverse-phase high-performance liquid chromatography, DCP-LA significantly activated PKC in PC-12 cells in a concentration-dependent (10 nM-100 microM) manner, with the maximal effect at 100 nM, and the DCP-LA effect was blocked by GF109203X, a PKC inhibitor, or a selective inhibitor peptide of the novel PKC isozyme PKC-epsilon. Furthermore, DCP-LA activated PKC in HEK-293 cells that was inhibited by the small, interfering RNA against PKC-epsilon. In the cell-free PKC assay, of the nine isozymes examined here, DCP-LA most strongly activated PKC-epsilon, with >7-fold potency over other PKC isozymes, in the absence of dioleoyl-phosphatidylserine and 1,2-dioleoyl-sn-glycerol; instead, the DCP-LA action was inhibited by dioleoyl-phosphatidylserine. DCP-LA also activated PKC-gamma, a conventional PKC, but to a much lesser extent compared with that for PKC-epsilon, by a mechanism distinct from PKC-epsilon activation. Thus, DCP-LA serves as a selective activator of PKC-epsilon, possibly by binding to the phosphatidylserine binding site on PKC-epsilon. These results may provide fresh insight into lipid signaling in PKC activation.

  4. Ethanol increases affinity of protein kinase C for phosphatidylserine

    SciTech Connect

    Chin, J.H.

    1986-03-01

    Protein kinase C is a calcium-dependent enzyme that requires phospholipid for its activation. It is present in relatively high concentration in the brain and may be involved in neuronal function. The present experiments test whether the membrane disorder induced by ethanol affects the activity of kinase C by changing its interaction with membrane lipid. Fractions rich in kinase C were purified from rat brain cytosol by DEAE-cellulose chromatography and Sephadex G-200 gel filtration. Enzyme activity was assayed by measuring the phosphorylation of histone H1. As expected, phosphatidylserine activated the enzyme, and the stimulation was further increased by the addition of calcium and/or diacylglycerol. At low concentration of free calcium (0.5-1..mu..M), ethanol (800 mM0 enhanced kinase C activity if the presence of phospholipid. similar results were observed in the absence of calcium. Double reciprocal plots of the data showed that ethanol increased the affinity of the enzyme for phosphatidylserine without affecting the V/sub max. The stimulation of kinase C activity by ethanol was not observed at high calcium concentrations. These experiments suggest that ethanol may activated protein kinase C at physiological levels of calcium by facilitating its transfer into the hydrophobic membrane environment.

  5. Enhancement of Anti-Inflammatory Activity of Curcumin Using Phosphatidylserine-Containing Nanoparticles in Cultured Macrophages

    PubMed Central

    Wang, Ji; Kang, Yu-Xia; Pan, Wen; Lei, Wan; Feng, Bin; Wang, Xiao-Juan

    2016-01-01

    Macrophages are one kind of innate immune cells, and produce a variety of inflammatory cytokines in response to various stimuli, such as oxidized low density lipoprotein found in the pathogenesis of atherosclerosis. In this study, the effect of phosphatidylserine on anti-inflammatory activity of curcumin-loaded nanostructured lipid carriers was investigated using macrophage cultures. Different amounts of phosphatidylserine were used in the preparation of curcumin nanoparticles, their physicochemical properties and biocompatibilities were then compared. Cellular uptake of the nanoparticles was investigated using a confocal laser scanning microscope and flow cytometry analysis in order to determine the optimal phosphatidylserine concentration. In vitro anti-inflammatory activities were evaluated in macrophages to test whether curcumin and phosphatidylserine have interactive effects on macrophage lipid uptake behavior and anti-inflammatory responses. Here, we showed that macrophage uptake of phosphatidylserine-containing nanostructured lipid carriers increased with increasing amount of phosphatidylserine in the range of 0%–8%, and decreased when the phosphatidylserine molar ratio reached over 12%. curcumin-loaded nanostructured lipid carriers significantly inhibited lipid accumulation and pro-inflammatory factor production in cultured macrophages, and evidently promoted release of anti-inflammatory cytokines, when compared with curcumin or phosphatidylserine alone. These results suggest that the delivery system using PS-based nanoparticles has great potential for efficient delivery of drugs such as curcumin, specifically targeting macrophages and modulation of their anti-inflammatory functions. PMID:27331813

  6. Brief Daily Exposures to Asian Females Reverses Perceptual Narrowing for Asian Faces in Caucasian Infants

    ERIC Educational Resources Information Center

    Anzures, Gizelle; Wheeler, Andrea; Quinn, Paul C.; Pascalis, Olivier; Slater, Alan M.; Heron-Delaney, Michelle; Tanaka, James W.; Lee, Kang

    2012-01-01

    Perceptual narrowing in the visual, auditory, and multisensory domains has its developmental origins during infancy. The current study shows that experimentally induced experience can reverse the effects of perceptual narrowing on infants' visual recognition memory of other-race faces. Caucasian 8- to 10-month-olds who could not discriminate…

  7. Phosphatidylserine externalization and procoagulant activation of erythrocytes induced by Pseudomonas aeruginosa virulence factor pyocyanin.

    PubMed

    Qadri, Syed M; Donkor, David A; Bhakta, Varsha; Eltringham-Smith, Louise J; Dwivedi, Dhruva J; Moore, Jane C; Pepler, Laura; Ivetic, Nikola; Nazi, Ishac; Fox-Robichaud, Alison E; Liaw, Patricia C; Sheffield, William P

    2016-04-01

    The opportunistic pathogen Pseudomonas aeruginosa causes a wide range of infections in multiple hosts by releasing an arsenal of virulence factors such as pyocyanin. Despite numerous reports on the pleiotropic cellular targets of pyocyanin toxicity in vivo, its impact on erythrocytes remains elusive. Erythrocytes undergo an apoptosis-like cell death called eryptosis which is characterized by cell shrinkage and phosphatidylserine (PS) externalization; this process confers a procoagulant phenotype on erythrocytes as well as fosters their phagocytosis and subsequent clearance from the circulation. Herein, we demonstrate that P. aeruginosa pyocyanin-elicited PS exposure and cell shrinkage in erythrocyte while preserving the membrane integrity. Mechanistically, exposure of erythrocytes to pyocyanin showed increased cytosolic Ca(2+) activity as well as Ca(2+) -dependent proteolytic processing of μ-calpain. Pyocyanin further up-regulated erythrocyte ceramide abundance and triggered the production of reactive oxygen species. Pyocyanin-induced increased PS externalization in erythrocytes translated into enhanced prothrombin activation and fibrin generation in plasma. As judged by carboxyfluorescein succinimidyl-ester labelling, pyocyanin-treated erythrocytes were cleared faster from the murine circulation as compared to untreated erythrocytes. Furthermore, erythrocytes incubated in plasma from patients with P. aeruginosa sepsis showed increased PS exposure as compared to erythrocytes incubated in plasma from healthy donors. In conclusion, the present study discloses the eryptosis-inducing effect of the virulence factor pyocyanin, thereby shedding light on a potentially important mechanism in the systemic complications of P. aeruginosa infection. PMID:26781477

  8. Brief daily exposures to Asian females reverses perceptual narrowing for Asian faces in Caucasian infants

    PubMed Central

    Anzures, Gizelle; Wheeler, Andrea; Quinn, Paul C.; Pascalis, Olivier; Slater, Alan M.; Heron-Delaney, Michelle; Tanaka, James W.; Lee, Kang

    2012-01-01

    Perceptual narrowing in the visual, auditory, and multisensory domains has its developmental origins in infancy. The present study shows that experimentally induced experience can reverse the effects of perceptual narrowing on infants’ visual recognition memory of other-race faces. Caucasian 8- to 10-month-olds who could not discriminate between novel and familiarized Asian faces at the beginning of testing were given brief daily experience with Asian female faces in the experimental condition and Caucasian female faces in the control condition. At the end of three weeks, only infants who received daily experience with Asian females showed above-chance recognition of novel Asian female and male faces. Further, infants in the experimental condition showed greater efficiency in learning novel Asian females compared to infants in the control condition. Thus, visual experience with a novel stimulus category can reverse the effects of perceptual narrowing in infancy via improved stimulus recognition and encoding. PMID:22625845

  9. Reversible Brain Abnormalities in People Without Signs of Mountain Sickness During High-Altitude Exposure

    PubMed Central

    Fan, Cunxiu; Zhao, Yuhua; Yu, Qian; Yin, Wu; Liu, Haipeng; Lin, Jianzhong; Yang, Tianhe; Fan, Ming; Gesang, Luobu; Zhang, Jiaxing

    2016-01-01

    A large proportion of lowlanders ascending to high-altitude (HA) show no signs of mountain sickness. Whether their brains have indeed suffered from HA environment and the persistent sequelae after return to lowland remain unknown. Thirty-one sea-level college students, who had a 30-day teaching on Qinghai-Tibet plateau underwent MRI scans before, during, and two months after HA exposure. Brain volume, cortical structures, and white matter microstructure were measured. Besides, serum neuron-specific enolase (NSE), C-reactive protein, and interleukin-6 and neuropsychiatric behaviors were tested. After 30-day HA exposure, the gray and white matter volumes and cortical surface areas significantly increased, with cortical thicknesses and curvatures changed in a wide spread regions; Anisotropy decreased with diffusivities increased in multiple sites of white matter tracts. Two months after HA exposure, cortical measurements returned to basal level. However, increased anisotropy with decreased diffusivities was observed. Behaviors and serum inflammatory factor did not significant changed during three time-point tests. NSE significantly decreased during HA but increased after HA exposure. Results suggest brain swelling occurred in people without neurological signs at HA, but no negative sequelae in cortical structures and neuropsychiatric functions were left after the return to lowlands. Reoxygenation changed white matter microstructure. PMID:27633944

  10. Reversible Brain Abnormalities in People Without Signs of Mountain Sickness During High-Altitude Exposure.

    PubMed

    Fan, Cunxiu; Zhao, Yuhua; Yu, Qian; Yin, Wu; Liu, Haipeng; Lin, Jianzhong; Yang, Tianhe; Fan, Ming; Gesang, Luobu; Zhang, Jiaxing

    2016-01-01

    A large proportion of lowlanders ascending to high-altitude (HA) show no signs of mountain sickness. Whether their brains have indeed suffered from HA environment and the persistent sequelae after return to lowland remain unknown. Thirty-one sea-level college students, who had a 30-day teaching on Qinghai-Tibet plateau underwent MRI scans before, during, and two months after HA exposure. Brain volume, cortical structures, and white matter microstructure were measured. Besides, serum neuron-specific enolase (NSE), C-reactive protein, and interleukin-6 and neuropsychiatric behaviors were tested. After 30-day HA exposure, the gray and white matter volumes and cortical surface areas significantly increased, with cortical thicknesses and curvatures changed in a wide spread regions; Anisotropy decreased with diffusivities increased in multiple sites of white matter tracts. Two months after HA exposure, cortical measurements returned to basal level. However, increased anisotropy with decreased diffusivities was observed. Behaviors and serum inflammatory factor did not significant changed during three time-point tests. NSE significantly decreased during HA but increased after HA exposure. Results suggest brain swelling occurred in people without neurological signs at HA, but no negative sequelae in cortical structures and neuropsychiatric functions were left after the return to lowlands. Reoxygenation changed white matter microstructure. PMID:27633944

  11. Reversible loss of reproductive fitness in zebrafish on chronic alcohol exposure.

    PubMed

    Dewari, Pooran Singh; Ajani, Funmilola; Kushawah, Gopal; Kumar, Damera Santhosh; Mishra, Rakesh K

    2016-02-01

    Alcoholism is one of the most prevalent diseases in society and causes significant health and social problems. Alcohol consumption by pregnant women is reported to cause adverse effects on the physical and psychological growth of the fetus. However, the direct effect of chronic alcohol consumption on reproductive fitness has not been tested. In recent years, the zebrafish (Danio rerio) has emerged as a versatile model system to study the effects of alcohol on behavior and embryonic development. We utilized the zebrafish model system to address the effect of chronic alcohol exposure (0.5% alcohol in the holding tank for 9 weeks) on reproductive capacity. We found a dramatic decrease in fecundity, measured by counting the number of eggs laid, when at least one of the parents is subject to chronic alcohol exposure. Interestingly, a 9-week alcohol withdrawal program completely restored the reproductive capacity of the treated subjects. In agreement with observations on fecundity, the chronic alcohol exposure leads to increased anxiety, as measured by the novel-tank diving assay. Conversely, the withdrawal program diminished heightened anxiety in alcohol-exposed subjects. Our results highlight the adverse effects of chronic alcohol exposure on the reproductive capacity of both males and females, and underscore the utility of the zebrafish model system to understand the biology of chronic alcoholism. PMID:26781213

  12. Phosphatidylserine index as a marker of the procoagulant phenotype of acute myelogenous leukemia cells

    NASA Astrophysics Data System (ADS)

    Tormoen, Garth W.; Recht, Olivia; Gruber, András; Levine, Ross L.; McCarty, Owen J. T.

    2013-10-01

    Patients with acute myelogenous leukemia (AML) are at risk for thrombotic complications. Risk to develop thrombosis is closely tied to leukemia subtype, and studies have shown an association between leukocytosis and thrombosis in AML M3. We evaluated the relative roles of cell count and the surface expression of tissue factor (TF) and phosphatidylserine (PS) in the procoagulant phenotype of AML cell lines. The TF-positive AML M3 cell lines, NB4 and HL60, and AML M2 cell line, AML14, exhibited both extrinsic tenase and prothrombinase activity in a purified system and promoted experimental thrombus formation. In contrast, the TF-negative AML cell line, HEL, exhibited only prothrombinase activity and did not affect the rate of occlusive thrombus formation. In plasma, NB4, HL60 and AML14 shortened clotting times in a cell-count, PS- and TF-dependent manner. Exposure of cultured NB4, HL60, and AML14 cells to the chemotherapeutic agent daunorubicin increased their extrinsic tenase activity and PS expression. Clot initiation time inversely correlated with logarithm of PS index, defined as the product of multiplying leukocyte count with cell surface PS exposure. We propose that leukemia cell PS index may serve as a biomarker for procoagulant activity.

  13. Sexually dimorphic alterations in locomotion and reversal learning after adolescent tetrahydrocannabinol exposure in the rat

    PubMed Central

    Harte, Lauren C.; Dow-Edwards, Diana

    2014-01-01

    Research suggests that use and abuse of marijuana can be especially harmful if it occurs during adolescence, a period of vast developmental changes throughout the brain. We examined the effects of 2 mg/kg Δ9-tetrahydrocannabinol (THC) administered daily via intra-peritoneal injections during juvenile/early adolescence (postnatal day 22–40) or late adolescence (postnatal day 41–60) on locomotor activity, development of tolerance, and acquisition/retention of spatial avoidance in adulthood. THC caused locomotor depression in both male and female animals dosed during early adolescence but only in female animals dosed during late adolescence. Evidence of reverse tolerance to THC was seen in early adolescent animals only. In the active place avoidance test (APA), male and female animals administered THC during early adolescence made more errors on the reversal trial requiring flexibility in learning, but in animals dosed during late adolescence there were no significant sex or treatment differences. The results of the locomotor activity study indicate that females may be more sensitive to the effects of THC than males, while results of both locomotor activity and APA studies suggest that early adolescents appear to be more vulnerable to these effects than late adolescents/young adults. PMID:20460150

  14. Toxicant Exposure and Bioaccumulation: A Common and Potentially Reversible Cause of Cognitive Dysfunction and Dementia

    PubMed Central

    Genuis, Stephen J.; Kelln, Kasie L.

    2015-01-01

    Juxtaposed alongside the ongoing rise in the incidence and prevalence of dementia, is the surge of recent research confirming widespread exposure and bioaccumulation of chemical toxicants. Evidence from sources such as the Centers for Disease Control reveals that most people have accrued varying degrees of assorted toxic pollutants including heavy metals, flame retardants, and pesticide residues within their bodies. It has been well established that many of these toxicants have neurodegenerative as well as neurodevelopmental impact as a result of various pathophysiologic mechanisms including neuronal mitochondrial toxicity and disruption of neurotransmitter regulation. Elimination of stockpiled toxicants from the body may diminish adverse toxicant impact on human biology and allow restoration of normal physiological function. Incorporating a review of medical literature on toxicant exposure and dementia with a case history of a lead-exposed individual diagnosed with dementia, this paper will discuss a much overlooked and potentially widespread cause of declining brain function and dementia. PMID:25722540

  15. Phosphatidylserine-binding protein lactadherin inhibits protein translocation across the ER membrane.

    PubMed

    Yamamoto, Hitoshi; Kida, Yuichiro; Sakaguchi, Masao

    2013-05-10

    Secretory and membrane proteins are translocated across and inserted into the endoplasmic reticulum membrane via translocon channels. To investigate the effect of the negatively-charged phospholipid phosphatidylserine on the translocation of nascent polypeptide chains through the translocon, we used the phosphatidylserine-binding protein lactadherin C2-domain. Lactadherin inhibited targeting of nascent chain to the translocon by signal sequence and the initiation of translocation. Moreover, lactadherin inhibited the movement of the translocating polypeptide chain regardless of the presence or absence of positively-charged residues. Phosphatidylserine might be critically involved in translocon function, but it is not a major determinant for translocation arrest of positively-charged residues. PMID:23583395

  16. TIM-4, a Receptor for Phosphatidylserine, Controls Adaptive Immunity by Regulating the Removal of Antigen-Specific T Cells

    PubMed Central

    Albacker, Lee A.; Karisola, Piia; Chang, Ya-Jen; Umetsu, Sarah E.; Zhou, Meixia; Akbari, Omid; Kobayashi, Norimoto; Baumgarth, Nicole; Freeman, Gordon J.; Umetsu, Dale T.; DeKruyff, Rosemarie H.

    2010-01-01

    Adaptive immunity is characterized by the expansion of an Ag-specific T cell population following Ag exposure. The precise mechanisms, however, that control the expansion and subsequent contraction in the number of Ag-specific T cells are not fully understood. We show that T cell/transmembrane, Ig, and mucin (TIM)-4, a receptor for phosphatidylserine, a marker of apoptotic cells, regulates adaptive immunity in part by mediating the removal of Ag-specific T cells during the contraction phase of the response. During Ag immunization or during infection with influenza A virus, blockade of TIM-4 on APCs increased the expansion of Ag-specific T cells, resulting in an increase in secondary immune responses. Conversely, overexpression of TIM-4 on APCs in transgenic mice reduced the number of Ag-specific T cells that remained after immunization, resulting in reduced secondary T cell responses. There was no change in the total number of cell divisions that T cells completed, no change in the per cell proliferative capacity of the remaining Ag-specific T cells, and no increase in the development of Ag-specific regulatory T cells in TIM-4 transgenic mice. Thus, TIM-4–expressing cells regulate adaptive immunity by mediating the removal of phosphatidylserine-expressing apoptotic, Ag-specific T cells, thereby controlling the number of Ag-specific T cells that remain after the clearance of Ag or infection. PMID:21037090

  17. Reverse osmosis membrane composition, structure and performance modification by bisulphite, iron(III), bromide and chlorite exposure.

    PubMed

    Ferrer, O; Gibert, O; Cortina, J L

    2016-10-15

    Reverse osmosis (RO) membrane exposure to bisulphite, chlorite, bromide and iron(III) was assessed in terms of membrane composition, structure and performance. Membrane composition was determined by Rutherford backscattering spectrometry (RBS) and membrane performance was assessed by water and chloride permeation, using a modified version of the solution-diffusion model. Iron(III) dosage in presence of bisulphite led to an autooxidation of the latter, probably generating free radicals which damaged the membrane. It comprised a significant raise in chloride passage (chloride permeation coefficient increased 5.3-5.1 fold compared to the virgin membrane under the conditions studied) rapidly. No major differences in terms of water permeability and membrane composition were observed. Nevertheless, an increase in the size of the network pores, and a raise in the fraction of aggregate pores of the polyamide (PA) layer were identified, but no amide bond cleavage was observed. These structural changes were therefore, in accordance with the transport properties observed. PMID:27470468

  18. Fetal hydrops, associated with maternal propylthiouracil exposure, reversed by intrauterine therapy.

    PubMed

    Yanai, N; Shveiky, D

    2004-02-01

    Thyroid hormone is essential for fetal neurological development. Among other etiologies, fetal hypothyroidism may be caused by maternal exposure to antithyroid drugs (ATDs). The most common presentation of fetal hypothyroidism is fetal goiter, which can cause dystocia, in addition to airway obstruction in the neonate. Intra-amniotic treatment with levothyroxine normalizes fetal thyroid status and reduces goiter size. We present a case of fetal hypothyroidism diagnosed in a patient who was treated with propylthiouracil (PTU) for Grave's disease. The fetus had marked hydrops fetalis and a large goiter. In addition, anal stenosis, vesicovaginal fistula, bilateral pyelectasia and polydactyly were diagnosed in the neonate. Intra-amniotic treatment with levothyroxine resulted in a regression of the hydrops and a reduction in the goiter size. A euthyroid, non-edematous, non-goitrous neonate was delivered. At the age of 27 months the child's psychomotor development was normal. The present case indicates that hydrops fetalis may be an unusual manifestation of fetal hypothyroidism, caused by intrauterine exposure to maternal antithyroid drugs (ATDs), and that it may be resolved by treatment with intra-amniotic levothyroxine. PMID:14770404

  19. MiADMSA reverses impaired mitochondrial energy metabolism and neuronal apoptotic cell death after arsenic exposure in rats

    SciTech Connect

    Dwivedi, Nidhi; Mehta, Ashish; Yadav, Abhishek; Binukumar, B.K.; Gill, Kiran Dip; Flora, Swaran J.S.

    2011-11-15

    Arsenicosis, due to contaminated drinking water, is a serious health hazard in terms of morbidity and mortality. Arsenic induced free radicals generated are known to cause cellular apoptosis through mitochondrial driven pathway. In the present study, we investigated the effect of arsenic interactions with various complexes of the electron transport chain and attempted to evaluate if there was any complex preference of arsenic that could trigger apoptosis. We also evaluated if chelation with monoisoamyl dimercaptosuccinic acid (MiADMSA) could reverse these detrimental effects. Our results indicate that arsenic exposure induced free radical generation in rat neuronal cells, which diminished mitochondrial potential and enzyme activities of all the complexes of the electron transport chain. Moreover, these complexes showed differential responses towards arsenic. These early events along with diminished ATP levels could be co-related with the later events of cytosolic migration of cytochrome c, altered bax/bcl{sub 2} ratio, and increased caspase 3 activity. Although MiADMSA could reverse most of these arsenic-induced altered variables to various extents, DNA damage remained unaffected. Our study for the first time demonstrates the differential effect of arsenic on the complexes leading to deficits in bioenergetics leading to apoptosis in rat brain. However, more in depth studies are warranted for better understanding of arsenic interactions with the mitochondria. -- Research highlights: Black-Right-Pointing-Pointer Arsenic impairs mitochondrial energy metabolism leading to neuronal apoptosis. Black-Right-Pointing-Pointer Arsenic differentially affects mitochondrial complexes, I - III and IV being more sensitive than complex II. Black-Right-Pointing-Pointer Arsenic-induced apoptosis initiates through ROS generation or impaired [Ca{sup 2+}]i homeostasis. Black-Right-Pointing-Pointer MiADMSA reverses arsenic toxicity via intracellular arsenic- chelation, antioxidant

  20. Characterization of a membrane-associated cytidine diphosphate-diacylglycerol-dependent phosphatidylserine synthase in bacilli.

    PubMed Central

    Dutt, A; Dowhan, W

    1981-01-01

    The synthesis of phosphatidylserine in two gram-positive aerobic bacteria has been partially characterized. We have located a cytidine 5'-diphospho-diacylglycerol:L-serine O-phosphatidyltransferase (phosphatidylserine synthase) activity in the membrane fraction of Bacillus licheniformis and Bacillus subtilis. The activity was demonstrated to be membrane associated by differential centrifugation, sucrose gradient centrifugation, and detergent solubilization. The direct involvement of cytidine 5'-diphospho-diacylglycerol in the reaction was demonstrated by the conversion of the liponucleotide phosphatidyl moiety to phosphatidylserine. This activity is dependent on divalent metal ion (manganese being optimal) and is stimulated by nonionic detergent and its product phosphatidylserine. Based on studies with various combinations of products and substrates, the reaction appears to follow a sequential BiBi kinetic mechanism. PMID:6267011

  1. Anti-Self Phosphatidylserine Antibodies Recognize Uninfected Erythrocytes Promoting Malarial Anemia.

    PubMed

    Fernandez-Arias, Cristina; Rivera-Correa, Juan; Gallego-Delgado, Julio; Rudlaff, Rachel; Fernandez, Clemente; Roussel, Camille; Götz, Anton; Gonzalez, Sandra; Mohanty, Akshaya; Mohanty, Sanjib; Wassmer, Samuel; Buffet, Pierre; Ndour, Papa Alioune; Rodriguez, Ana

    2016-02-10

    Plasmodium species, the parasitic agents of malaria, invade erythrocytes to reproduce, resulting in erythrocyte loss. However, a greater loss is caused by the elimination of uninfected erythrocytes, sometimes long after infection has been cleared. Using a mouse model, we found that Plasmodium infection induces the generation of anti-self antibodies that bind to the surface of uninfected erythrocytes from infected, but not uninfected, mice. These antibodies recognize phosphatidylserine, which is exposed on the surface of a fraction of uninfected erythrocytes during malaria. We find that phosphatidylserine-exposing erythrocytes are reticulocytes expressing high levels of CD47, a "do-not-eat-me" signal, but the binding of anti-phosphatidylserine antibodies mediates their phagocytosis, contributing to anemia. In human patients with late postmalarial anemia, we found a strong inverse correlation between the levels of anti-phosphatidylserine antibodies and plasma hemoglobin, suggesting a similar role in humans. Inhibition of this pathway may be exploited for treating malarial anemia.

  2. Effective Binding of a Phosphatidylserine-Targeting Antibody to Ebola Virus Infected Cells and Purified Virions

    PubMed Central

    Dowall, S. D.; Graham, V. A.; Corbin-Lickfett, K.; Empig, C.; Schlunegger, K.; Bruce, C. B.; Easterbrook, L.; Hewson, R.

    2015-01-01

    Ebola virus is responsible for causing severe hemorrhagic fevers, with case fatality rates of up to 90%. Currently, no antiviral or vaccine is licensed against Ebola virus. A phosphatidylserine-targeting antibody (PGN401, bavituximab) has previously been shown to have broad-spectrum antiviral activity. Here, we demonstrate that PGN401 specifically binds to Ebola virus and recognizes infected cells. Our study provides the first evidence of phosphatidylserine-targeting antibody reactivity against Ebola virus. PMID:25815346

  3. Mercury Induces the Externalization of Phosphatidyl-Serine in Human Renal Proximal Tubule (HK-2) Cells

    PubMed Central

    Sutton, Dwayne J.; Tchounwou, Paul B.

    2007-01-01

    The underlying mechanism for the biological activity of inorganic mercury is believed to be the high affinity binding of divalent mercuric cations to thiols of sulfhydryl groups of proteins. A comprehensive analysis of published data indicates that inorganic mercury is one of the most environmentally abundant toxic metals, is a potent and selective nephrotoxicant that preferentially accumulates in the kidneys, and is known to produce cellular injury in the kidneys. Binding sites are present in the proximal tubules, and it is in the epithelial cells of these tubules that toxicants such as inorganic mercury are reabsorbed. This can affect the enzymatic activity and the structure of various proteins. Mercury may alter protein and membrane structure and function in the epithelial cells and this alteration may result in long term residual effects. This research was therefore designed to evaluate the dose-response relationship in human renal proximal tubule (HK-2) cells following exposure to inorganic mercury. Cytotoxicity was evaluated using the MTT assay for cell viability. The Annexin-V assay was performed by flow cytometry to determine the extent of phosphatidylserine externalization. Cells were exposed to mercury for 24 hours at doses of 0, 1, 2, 3, 4, 5, and 6 μg/mL. Cytotoxicity experiments yielded a LD50 value of 4.65 ± 0.6 μg/mL indicating that mercury is highly toxic. The percentages of cells undergoing early apoptosis were 0.70 ± 0.03%, 10.0 ± 0.02%, 11.70 ± 0.03%, 15.20 ± 0.02%, 16.70 ± 0.03%, 24.20 ±0.02%, and 25.60 ± 0.04% at treatments of 0, 1, 2, 3, 4, 5, and 6 μg/mL of mercury respectively. This indicates a dose-response relationship with regard to mercury-induced cytotoxicity and the externalization of phosphatidylserine in HK-2 cells. PMID:17617677

  4. Interaction of an annexin V homodimer (Diannexin) with phosphatidylserine on cell surfaces and consequent antithrombotic activity.

    PubMed

    Kuypers, Frans A; Larkin, Sandra K; Emeis, Jef J; Allison, Anthony C

    2007-03-01

    Annexin V (AV), a protein with anticoagulant activity, exerts antithrombotic activity by binding to phosphatidylserine (PS), inhibiting activation of serine proteases important in blood coagulation. The potential use of this protein as an anticoagulant is limited as it rapidly passes from the blood into the kidneys due to its relatively small size (36 kDa). We used recombinant DNA technology to produce a homodimer of human AV (DAV, 73 kDa), which exceeds the renal filtration threshold, and has a 6.5-hour half-life in the rat circulation. Human red blood cells with externalized PS were used to show that DAV had a higher affinity for PS-exposing cells than AV. DAV labeling sensitively identifies PS-exposing cells, was found to be a potent inhibitor of the activity of the prothombinase complexes and inhibits the ability of secretory phospholipaseA(2) to hydrolyze phospholipids of PS-exposing cells, reducing the formation of mediators of blood coagulation and reperfusion injury. DAV exerts dose-dependent antithrombotic activity in rat veins. This combination of activities suggests that DAV is a valuable probe to measure PS exposure and may be efficacious as a novel drug in a wide range of clinical situations.

  5. Interaction of dicaproyl phosphatidylserine with recombinant factor VIII and its impact on immunogenicity.

    PubMed

    Purohit, Vivek S; Balasubramanian, Sathyamangalam V

    2006-01-01

    Replacement therapy with exogenous recombinant factor VIII (rFVIII) to control bleeding episodes results in the development of inhibitory antibodies in 15% to 30% of hemophilia A patients. The inhibitory antibodies are mainly directed against specific and universal immunodominant epitopes located in the C2 domain. Previously we have shown that complexation of O-phospho-L-serine (phosphatidylserine head group) with the phospholipid binding region of the C2 domain can lead to an overall reduction in the immunogenicity of rFVIII. Here, we have investigated the hypothesis that dicaproyl phosphatidylserine, a short-chain water-soluble phospholipid, can reduce the immunogenicity of rFVIII. Circular dichroism and fluorescence spectroscopy studies suggest that dicaproyl phosphatidylserine interacts with rFVIII, causing subtle changes in the tertiary and secondary structure of the protein. Sandwich enzyme-linked immunosorbent assay studies indicate that dicaproyl phosphatidylserine probably interacts with the phospholipid binding region of the C2 domain. The immunogenicity of FVIII-dicaproyl phosphatidylserine complexes prepared at concentrations above and below the critical micellar concentrations of the lipid were evaluated in hemophilia A mice. Our results suggest that micellar dicaproyl phosphatidylserine may be useful to reduce the immunogenicity of rFVIII preparations.

  6. Persistence of a hyperthermic sign-reversal during nitrous oxide inhalation despite cue-exposure treatment with and without a drug-onset cue

    PubMed Central

    Kaiyala, Karl J; Woods, Stephen C; Ramsay, Douglas S

    2014-01-01

    We asked whether chronic tolerance and the hyperthermic sign-reversal induced by repeated 60% N2O exposures could be extinguished using a cue-exposure paradigm. Rats received 18 N2O administrations in a total calorimetry system that simultaneously measures core temperature (Tc), metabolic heat production (HP), and body heat loss (HL). Each exposure entailed a 2-h baseline period followed by a 1.5-h N2O exposure. The 18 drug exposures induced a robust intra-administration hyperthermia in which the initial hypothermic effect of N2O inverted to a significant hyperthermic sign-reversal during N2O inhalation due primarily to an acquired robust increase in HP. The rats were then randomized to one of 3 extinction procedures (n = 8/procedure) over a 20-d interval: 1) a N2O-abstinent home-cage group (HC) that received only the usual animal care; 2) a cue-exposure group (CEXP) in which the animals were placed in the calorimeter 8 times but received no N2O; and 3) a drug-onset-cue group (DOC) in which animals received a brief N2O exposure in the calorimeter that mimicked the first 3 min of an actual 60% N2O trial. Following the extinction sessions, all rats received a 60% N2O test trial and Tc, HP and HL were assessed. The hyperthermic sign-reversal remained fully intact during the test trial, with no significant differences observed among groups in any post-baseline change in any thermal outcome. These data suggest that cue exposure may not be an efficacious strategy to reduce sign-reversals that develop with chronic drug use. PMID:25938128

  7. Imaging of Brain Tumors With Paramagnetic Vesicles Targeted to Phosphatidylserine

    PubMed Central

    Winter, Patrick M.; Pearce, John; Chu, Zhengtao; McPherson, Christopher M.; Takigiku, Ray; Lee, Jing-Huei; Qi, Xiaoyang

    2014-01-01

    Purpose To investigate paramagnetic saposin C and dioleylphosphatidylserine (SapC-DOPS) vesicles as a targeted contrast agent for imaging phosphatidylserine (PS) expressed by glioblastoma multiforme (GBM) tumors. Materials and Methods Gd-DTPA-BSA/SapC-DOPS vesicles were formulated, and the vesicle diameter and relaxivity were measured. Targeting of Gd-DTPA-BSA/ SapC-DOPS vesicles to tumor cells in vitro and in vivo was compared with nontargeted paramagnetic vesicles (lacking SapC). Mice with GBM brain tumors were imaged at 3, 10, 20, and 24 h postinjection to measure the relaxation rate (R1) in the tumor and the normal brain. Results The mean diameter of vesicles was 175 nm, and the relaxivity at 7 Tesla was 3.32 (s*mM)−1 relative to the gadolinium concentration. Gd-DTPA-BSA/SapC-DOPS vesicles targeted cultured cancer cells, leading to an increased R1 and gadolinium level in the cells. In vivo, Gd-DTPA-BSA/SapC-DOPS vesicles produced a 9% increase in the R1 of GBM brain tumors in mice 10 h postinjection, but only minimal changes (1.2% increase) in the normal brain. Nontargeted paramagnetic vesicles yielded minimal change in the tumor R1 at 10 h postinjection (1.3%). Conclusion These experiments demonstrate that Gd-DTPA-BSA/SapC-DOPS vesicles can selectively target implanted brain tumors in vivo, providing noninvasive mapping of the cancer biomarker PS. PMID:24797437

  8. Dysferlin-mediated phosphatidylserine sorting engages macrophages in sarcolemma repair.

    PubMed

    Middel, Volker; Zhou, Lu; Takamiya, Masanari; Beil, Tanja; Shahid, Maryam; Roostalu, Urmas; Grabher, Clemens; Rastegar, Sepand; Reischl, Markus; Nienhaus, Gerd Ulrich; Strähle, Uwe

    2016-01-01

    Failure to repair the sarcolemma leads to muscle cell death, depletion of stem cells and myopathy. Hence, membrane lesions are instantly sealed by a repair patch consisting of lipids and proteins. It has remained elusive how this patch is removed to restore cell membrane integrity. Here we examine sarcolemmal repair in live zebrafish embryos by real-time imaging. Macrophages remove the patch. Phosphatidylserine (PS), an 'eat-me' signal for macrophages, is rapidly sorted from adjacent sarcolemma to the repair patch in a Dysferlin (Dysf) dependent process in zebrafish and human cells. A previously unrecognized arginine-rich motif in Dysf is crucial for PS accumulation. It carries mutations in patients presenting with limb-girdle muscular dystrophy 2B. This underscores the relevance of this sequence and uncovers a novel pathophysiological mechanism underlying this class of myopathies. Our data show that membrane repair is a multi-tiered process involving immediate, cell-intrinsic mechanisms as well as myofiber/macrophage interactions. PMID:27641898

  9. Identification of N-Acyl Phosphatidylserine Molecules in Eukaryotic Cells

    PubMed Central

    Guan, Ziqiang; Li, Shengrong; Smith, Dale C.; Shaw, Walter A.; Raetz, Christian R. H.

    2008-01-01

    While profiling the lipidome of the mouse brain by mass spectrometry, we discovered a novel family of N-acyl phosphatidylserine (N-acyl-PS) molecules. These N-acyl-PS species were enriched by DEAE-cellulose column chromatography, and they were then characterized by accurate mass measurements, tandem mass spectrometry, liquid chromatography/mass spectrometry, and comparison to an authentic standard. Mouse brain N-acyl-PS molecules are heterogeneous and constitute about 0.1 % of the total lipid. In addition to various ester-linked fatty acyl chains on their glycerol backbones, the complexity of the N-acyl-PS series is further increased by the presence of diverse amide-linked N-acyl chains, which include saturated, mono-unsaturated and poly-unsaturated species. N-acyl-PS molecular species were also detected in the lipids of pig brain, mouse RAW264.7 macrophage tumor cells and yeast, but not E. coli. N-acyl-PSs may be biosynthetic precursors of N-acyl serine molecules, such as the recently reported signaling lipid N-arachidonoyl serine from bovine brain. We suggest that a phospholipase D might cleave N-acyl-PS to generate N-acyl serine, in analogy to the biosynthesis of the endocannabinoid N-arachidonoyl ethanolamine (anadamide) from N-arachidonoyl phosphatidylethanolamine. PMID:18031065

  10. Dysferlin-mediated phosphatidylserine sorting engages macrophages in sarcolemma repair.

    PubMed

    Middel, Volker; Zhou, Lu; Takamiya, Masanari; Beil, Tanja; Shahid, Maryam; Roostalu, Urmas; Grabher, Clemens; Rastegar, Sepand; Reischl, Markus; Nienhaus, Gerd Ulrich; Strähle, Uwe

    2016-09-19

    Failure to repair the sarcolemma leads to muscle cell death, depletion of stem cells and myopathy. Hence, membrane lesions are instantly sealed by a repair patch consisting of lipids and proteins. It has remained elusive how this patch is removed to restore cell membrane integrity. Here we examine sarcolemmal repair in live zebrafish embryos by real-time imaging. Macrophages remove the patch. Phosphatidylserine (PS), an 'eat-me' signal for macrophages, is rapidly sorted from adjacent sarcolemma to the repair patch in a Dysferlin (Dysf) dependent process in zebrafish and human cells. A previously unrecognized arginine-rich motif in Dysf is crucial for PS accumulation. It carries mutations in patients presenting with limb-girdle muscular dystrophy 2B. This underscores the relevance of this sequence and uncovers a novel pathophysiological mechanism underlying this class of myopathies. Our data show that membrane repair is a multi-tiered process involving immediate, cell-intrinsic mechanisms as well as myofiber/macrophage interactions.

  11. Dysferlin-mediated phosphatidylserine sorting engages macrophages in sarcolemma repair

    PubMed Central

    Middel, Volker; Zhou, Lu; Takamiya, Masanari; Beil, Tanja; Shahid, Maryam; Roostalu, Urmas; Grabher, Clemens; Rastegar, Sepand; Reischl, Markus; Nienhaus, Gerd Ulrich; Strähle, Uwe

    2016-01-01

    Failure to repair the sarcolemma leads to muscle cell death, depletion of stem cells and myopathy. Hence, membrane lesions are instantly sealed by a repair patch consisting of lipids and proteins. It has remained elusive how this patch is removed to restore cell membrane integrity. Here we examine sarcolemmal repair in live zebrafish embryos by real-time imaging. Macrophages remove the patch. Phosphatidylserine (PS), an ‘eat-me' signal for macrophages, is rapidly sorted from adjacent sarcolemma to the repair patch in a Dysferlin (Dysf) dependent process in zebrafish and human cells. A previously unrecognized arginine-rich motif in Dysf is crucial for PS accumulation. It carries mutations in patients presenting with limb-girdle muscular dystrophy 2B. This underscores the relevance of this sequence and uncovers a novel pathophysiological mechanism underlying this class of myopathies. Our data show that membrane repair is a multi-tiered process involving immediate, cell-intrinsic mechanisms as well as myofiber/macrophage interactions. PMID:27641898

  12. CHRONIC DIETARY EXPOSURE WITH INTERMITTENT SPIKE DOSES OF CHLORPYRIFOS FAILS TO ALTER FLASH OR PATTERN REVERSAL EVOKED POTENTIALS IN RATS.

    EPA Science Inventory

    Human exposure to pesticides is often characterized by chronic low level exposure with intermittent spiked higher exposures. Visual disturbances are often reported following exposure to xenobiotics, and cholinesterase-inhibiting compounds have been reported to alter visual functi...

  13. Calorimetric and spectroscopic studies of the thermotropic phase behavior of lipid bilayer model membranes composed of a homologous series of linear saturated phosphatidylserines.

    PubMed Central

    Lewis, R N; McElhaney, R N

    2000-01-01

    The thermotropic phase behavior of lipid bilayer model membranes composed of the even-numbered, N-saturated 1,2-diacyl phosphatidylserines was studied by differential scanning calorimetry and by Fourier-transform infrared and (31)P-nuclear magnetic resonance spectroscopy. At pH 7.0, 0.1 M NaCl and in the absence of divalent cations, aqueous dispersions of these lipids, which have not been incubated at low temperature, exhibit a single calorimetrically detectable phase transition that is fully reversible, highly cooperative, and relatively energetic, and the transition temperatures and enthalpies increase progressively with increases in hydrocarbon chain length. Our spectroscopic observations confirm that this thermal event is a lamellar gel (L(beta))-to-lamellar liquid crystalline (L(alpha)) phase transition. However, after low temperature incubation, the L(beta)/L(alpha) phase transition of dilauroyl phosphatidylserine is replaced by a higher temperature, more enthalpic, and less cooperative phase transition, and an additional lower temperature, less enthalpic, and less cooperative phase transition appears in the longer chain phosphatidylserines. Our spectroscopic results indicate that this change in thermotropic phase behavior when incubated at low temperatures results from the conversion of the L(beta) phase to a highly ordered lamellar crystalline (L(c)) phase. Upon heating, the L(c) phase of dilauroyl phosphatidylserine converts directly to the L(alpha) phase at a temperature slightly higher than that of its original L(beta)/L(alpha) phase transition. Calorimetrically, this process is manifested by a less cooperative but considerably more energetic, higher-temperature phase transition, which replaces the weaker L(beta)/L(alpha) phase transition alluded to above. However, with the longer chain compounds, the L(c) phase first converts to the L(beta) phase at temperatures some 10-25 degrees C below that at which the L(beta) phase converts to the L(alpha) phase

  14. Gain-of-function mutations in the phosphatidylserine synthase 1 (PTDSS1) gene cause Lenz-Majewski syndrome.

    PubMed

    Sousa, Sérgio B; Jenkins, Dagan; Chanudet, Estelle; Tasseva, Guergana; Ishida, Miho; Anderson, Glenn; Docker, James; Ryten, Mina; Sa, Joaquim; Saraiva, Jorge M; Barnicoat, Angela; Scott, Richard; Calder, Alistair; Wattanasirichaigoon, Duangrurdee; Chrzanowska, Krystyna; Simandlová, Martina; Van Maldergem, Lionel; Stanier, Philip; Beales, Philip L; Vance, Jean E; Moore, Gudrun E

    2014-01-01

    Lenz-Majewski syndrome (LMS) is a syndrome of intellectual disability and multiple congenital anomalies that features generalized craniotubular hyperostosis. By using whole-exome sequencing and selecting variants consistent with the predicted dominant de novo etiology of LMS, we identified causative heterozygous missense mutations in PTDSS1, which encodes phosphatidylserine synthase 1 (PSS1). PSS1 is one of two enzymes involved in the production of phosphatidylserine. Phosphatidylserine synthesis was increased in intact fibroblasts from affected individuals, and end-product inhibition of PSS1 by phosphatidylserine was markedly reduced. Therefore, these mutations cause a gain-of-function effect associated with regulatory dysfunction of PSS1. We have identified LMS as the first human disease, to our knowledge, caused by disrupted phosphatidylserine metabolism. Our results point to an unexplored link between phosphatidylserine synthesis and bone metabolism.

  15. Gain-of-function mutations in the phosphatidylserine synthase 1 (PTDSS1) gene cause Lenz-Majewski syndrome.

    PubMed

    Sousa, Sérgio B; Jenkins, Dagan; Chanudet, Estelle; Tasseva, Guergana; Ishida, Miho; Anderson, Glenn; Docker, James; Ryten, Mina; Sa, Joaquim; Saraiva, Jorge M; Barnicoat, Angela; Scott, Richard; Calder, Alistair; Wattanasirichaigoon, Duangrurdee; Chrzanowska, Krystyna; Simandlová, Martina; Van Maldergem, Lionel; Stanier, Philip; Beales, Philip L; Vance, Jean E; Moore, Gudrun E

    2014-01-01

    Lenz-Majewski syndrome (LMS) is a syndrome of intellectual disability and multiple congenital anomalies that features generalized craniotubular hyperostosis. By using whole-exome sequencing and selecting variants consistent with the predicted dominant de novo etiology of LMS, we identified causative heterozygous missense mutations in PTDSS1, which encodes phosphatidylserine synthase 1 (PSS1). PSS1 is one of two enzymes involved in the production of phosphatidylserine. Phosphatidylserine synthesis was increased in intact fibroblasts from affected individuals, and end-product inhibition of PSS1 by phosphatidylserine was markedly reduced. Therefore, these mutations cause a gain-of-function effect associated with regulatory dysfunction of PSS1. We have identified LMS as the first human disease, to our knowledge, caused by disrupted phosphatidylserine metabolism. Our results point to an unexplored link between phosphatidylserine synthesis and bone metabolism. PMID:24241535

  16. Exposure to polymers reverses inhibition of pulmonary surfactant by serum, meconium, or cholesterol in the captive bubble surfactometer.

    PubMed

    López-Rodríguez, Elena; Ospina, Olga Lucía; Echaide, Mercedes; Taeusch, H William; Pérez-Gil, Jesús

    2012-10-01

    Dysfunction of pulmonary surfactant in the lungs is associated with respiratory pathologies such as acute respiratory distress syndrome or meconium aspiration syndrome. Serum, cholesterol, and meconium have been described as inhibitory agents of surfactant's interfacial activity once these substances appear in alveolar spaces during lung injury and inflammation. The deleterious action of these agents has been only partly evaluated under physiologically relevant conditions. We have optimized a protocol to assess surfactant inhibition by serum, cholesterol, or meconium in the captive bubble surfactometer. Specific measures of surface activity before and after native surfactant was exposed to inhibitors included i), film formation, ii), readsorption of material from surface-associated reservoirs, and iii), interfacial film dynamics during compression-expansion cycling. Results show that serum creates a steric barrier that impedes surfactant reaching the interface. A mechanical perturbation of this barrier allows native surfactant to compete efficiently with serum to form a highly surface-active film. Exposure of native surfactant to cholesterol or meconium, on the other hand, modifies the compressibility of surfactant films though optimal compressibility properties recover on repetitive compression-expansion cycling. Addition of polymers like dextran or hyaluronic acid to surfactant fully reverses inhibition by serum. These polymers also prevent surfactant inhibition by cholesterol or meconium, suggesting that the protective action of polymers goes beyond the mere enhancement of interfacial adsorption as described by depletion force theories.

  17. La3+-induced fusion of phosphatidylserine liposomes. Close approach, intermembrane intermediates, and the electrostatic surface potential.

    PubMed Central

    Bentz, J; Alford, D; Cohen, J; Düzgüneş, N

    1988-01-01

    The fusion of large unilamellar phosphatidylserine liposomes (PS LUV) induced by La3+ has been monitored using the 1-aminoapthalene-3,6,8-trisulfonic acid/p-xylenebis(pyridinium bromide) (ANTS/DPX) fluorescence assay for the mixing of aqueous contents. The fusion event is extensive and nonleaky, with up to 95% mixing of contents in the fused liposomes. However, addition of excess EDTA leads to disruption of the fusion products in a way that implies the existence of metastable intermembrane contact sites. The maximal fusion activity occurs between 10 and 100 microM La3+ and fusion can be terminated rapidly, without loss of contents, by the addition of excess La3+, e.g., 1 mM La3+ at pH 7.4. This observation is explained by the very large intrinsic binding constant (approximately 10(5) M-1) of La3+ to the PS headgroup, as measured by microelectrophoresis. Addition of 1 mM La3+ causes charge reversal of the membrane and a large positive surface potential. La3+ binding to PS causes the release of a proton. These data can be explained if La3+ can chelate to PS at two sites, with one of the sites being the primary amino group. This binding model successfully predicts that at pH 4.5 fusion occurs up to 2 mM La3+, due to reduced La3+ binding at low pH. We conclude that the general mechanism of membrane fusion includes three kinetic steps. In addition to (a) aggregation, there is (b) the close approach of the surfaces, or thinning of the hydration layer, and (c) the formation of intermembrane intermediates which determine the extent to which membrane destabilization leads to fusion (mixing of aqueous contents), as opposed to lysis. The lifetime of these intermembrane intermediates appears to depend upon La3+ binding to both PS sites. PMID:3382713

  18. Attenuated total reflection (ATR) Fourier transform infrared spectroscopy of dimyristoyl phosphatidylserine-cholesterol mixtures.

    PubMed

    Bach, D; Miller, I R

    2001-10-01

    Mixtures of cholesterol with dimyristoyl phosphatidylserine or deuterated dimyristoyl phosphatidylserine were investigated by polarized and non polarized attenuated total reflection (ATR) Fourier transform infrared (FTIR) Spectroscopy. From polarized spectra the dichroic ratios of various vibrations as a function of cholesterol were calculated. Dichroic ratios of methylene vibration (CH(2)) 2934 cm(-1) of cholesterol decreases with increase of cholesterol concentration leveling off in the region where cholesterol phase separation takes place. The orientation of deuterated methylene (CD(2)) symmetric and asymmetric bands of the deuterated dimyristoyl phosphatidylserine is influenced little by cholesterol. In the polar region of dimyristoyl phosphatidylserine no effect of cholesterol on the dichroic ratios of carbonyl (C==O) and asymmetric phosphate (PO(2)(-)) vibrations were detected. For nonpolarized spectra the broad bands in the polar region of the phospholipid were deconvoluted. The carbonyl band (C==O) in pure dimyristoyl phosphatidylserine is composed of five bands; in the presence of increasing concentrations of cholesterol conformational change of these vibrations takes place evolving into one predominant band. Similar conformational change takes place in the presence of 75 molecules water/molecule DMPS. For the asymmetric phosphate band very small shifts due to interaction with cholesterol were detected.

  19. Characterization of osseointegrative phosphatidylserine and cholesterol orthopaedic implant coatings

    NASA Astrophysics Data System (ADS)

    Rodgers, William Paul, III

    Total joint arthroplasties are one of the most successful surgeries available today for improving patients' quality of life. Increasing demand is driven largely by an ageing population and an increased occurrence of obesity. Current patient options have significant shortcomings. Nearly a third of patients require a revision surgery before the implant is 15 years old, and those who have revision surgeries are at an increased risk of requiring additional reoperations. A recent implant technology that has shown to be effective at improving bone to implant integration is the use of phosphatidylserine (DOPS) coatings. These coatings are challenging to analyze and measure due to their highly dynamic, soft, rough, thick, and optically diffractive properties. Previous work had difficulty investigating pertinent parameters for these coating's development due in large part to a lack of available analytical techniques and a dearth of understanding of the micro- and nano-structural configuration of the coatings. This work addresses the lack of techniques available for use with DOPS coatings through the development of original methods of measurement, including the use of scanning white light interferometry and nanoindentation. These techniques were then applied for the characterization of DOPS coatings and the study of effects from several factors: 1. influence of adding calcium and cholesterol to the coatings, 2. effects of composition and roughness on aqueous contact angles, and 3. impact of ageing and storage environment on the coatings. Using these newly developed, highly repeatable quantitative analysis methods, this study sheds light on the microstructural configuration of the DOPS coatings and elucidates previously unexplained phenomena of the coatings. Cholesterol was found to supersaturate in the coatings at high concentration and phase separate into an anhydrous crystalline form, while lower concentrations were found to significantly harden the coatings. Morphological

  20. Synergies of phosphatidylserine and protein disulfide isomerase in tissue factor activation

    PubMed Central

    Langer, Florian; Ruf, Wolfram

    2014-01-01

    Summary Tissue factor (TF), the cellular receptor and cofactor for factor VII/VIIa, initiates haemostasis and thrombosis. Initial tissue distribution studies suggested that TF was sequestered from the circulation and only present at perivascular sites. However, there is now clear evidence that TF also exists as a blood-borne form with critical contributions not only to arterial thrombosis following plaque rupture and to venous thrombosis following endothelial perturbation, but also to various other clotting abnormalities associated with trauma, infection, or cancer. Because thrombin generation, fibrin deposition, and platelet aggregation in the contexts of haemostasis, thrombosis, and pathogen defence frequently occur without TF de novo synthesis, considerable efforts are still directed to understanding the molecular events underlying the conversion of predominantly non-coagulant or cryptic TF on the surface of haematopoietic cells to a highly procoagulant molecule following cellular injury or stimulation. This article will review some of the still controversial mechanisms implicated in cellular TF activation or decryption with particular focus on the coordinated effects of outer leaflet phosphatidylserine exposure and thiol-disulfide exchange pathways involving protein disulfide isomerase (PDI). In this regard, our recent findings of ATP-triggered stimulation of the purinergic P2X7 receptor on myeloid and smooth muscle cells resulting in potent TF activation and shedding of procoagulant microparticles as well as of rapid monocyte TF decryption following antithymocyte globulin-dependent membrane complement fixation have delineated specific PDI-dependent pathways of cellular TF activation and thus illustrated additional and novel links in the coupling of inflammation and coagulation. PMID:24452853

  1. Chronic cocaine exposure in adolescence: Effects on spatial discrimination reversal, delay discounting, and performance on fixed-ratio schedules in mice.

    PubMed

    Pope, Derek A; Boomhower, Steven R; Hutsell, Blake A; Teixeira, Kathryn M; Newland, M Christopher

    2016-04-01

    Adolescence is marked by the continued development of the neural pathways that support choice and decision-making, particularly those involving dopamine signaling. Cocaine exposure during adolescence may interfere with this development and manifest as increased perseveration and delay discounting in adulthood, behavioral processes that are related to drug addiction. Adolescent mice were exposed to 30mg/kg/day of cocaine (n=11) or saline vehicle (n=10) for 14days and behavior was assessed in adulthood. In Experiment 1, performance on a spatial-discrimination-reversal procedure was evaluated. In the first two sessions following the first reversal, cocaine-exposed mice produced more preservative errors relative to controls. In Experiment 2, cocaine-exposed mice displayed steeper delay discounting than saline-exposed mice, effects that were reversed by acute cocaine administration. Experiment 3 examined responding maintained by a range of fixed-ratio schedules of reinforcement. An analysis based on a theoretical framework called Mathematical Principles of Reinforcement (MPR) was applied to response-rate functions of individual mice. According to MPR, differences in response-rate functions in adulthood were due to a steepening of the delay-of-reinforcement gradient, disrupted motoric capacity (lower maximum response rates), and enhanced reinforcer efficacy for the adolescent cocaine- compared with saline-exposed mice. Overall, these experiments suggest that chronic exposure to cocaine during adolescence may impair different features of 'executive functions' in adulthood, and these may be related to distortions in the impact of reinforcing events.

  2. Long term exposure to combination paradigm of environmental enrichment, physical exercise and diet reverses the spatial memory deficits and restores hippocampal neurogenesis in ventral subicular lesioned rats.

    PubMed

    Kapgal, Vijayakumar; Prem, Neethi; Hegde, Preethi; Laxmi, T R; Kutty, Bindu M

    2016-04-01

    Subiculum is an important structure of the hippocampal formation and plays an imperative role in spatial learning and memory functions. We have demonstrated earlier the cognitive impairment following bilateral ventral subicular lesion (VSL) in rats. We found that short term exposure to enriched environment (EE) did not help to reverse the spatial memory deficits in water maze task suggesting the need for an appropriate enriched paradigm towards the recovery of spatial memory. In the present study, the efficacy of long term exposure of VSL rats to combination paradigm of environmental enrichment (EE), physical exercise and 18 C.W. diet (Combination Therapy - CT) in reversing the spatial memory deficits in Morris water maze task has been studied. Ibotenate lesioning of ventral subiculum produced significant impairment of performance in the Morris water maze and reduced the hippocampal neurogenesis in rats. Post lesion exposure to C.T. restored the hippocampal neurogenesis and improved the spatial memory functions in VSL rats. Our study supports the hypothesis that the combination paradigm is critical towards the development of an enhanced behavioral and cognitive experience especially in conditions of CNS insults and the associated cognitive dysfunctions. PMID:26851129

  3. Long term exposure to combination paradigm of environmental enrichment, physical exercise and diet reverses the spatial memory deficits and restores hippocampal neurogenesis in ventral subicular lesioned rats.

    PubMed

    Kapgal, Vijayakumar; Prem, Neethi; Hegde, Preethi; Laxmi, T R; Kutty, Bindu M

    2016-04-01

    Subiculum is an important structure of the hippocampal formation and plays an imperative role in spatial learning and memory functions. We have demonstrated earlier the cognitive impairment following bilateral ventral subicular lesion (VSL) in rats. We found that short term exposure to enriched environment (EE) did not help to reverse the spatial memory deficits in water maze task suggesting the need for an appropriate enriched paradigm towards the recovery of spatial memory. In the present study, the efficacy of long term exposure of VSL rats to combination paradigm of environmental enrichment (EE), physical exercise and 18 C.W. diet (Combination Therapy - CT) in reversing the spatial memory deficits in Morris water maze task has been studied. Ibotenate lesioning of ventral subiculum produced significant impairment of performance in the Morris water maze and reduced the hippocampal neurogenesis in rats. Post lesion exposure to C.T. restored the hippocampal neurogenesis and improved the spatial memory functions in VSL rats. Our study supports the hypothesis that the combination paradigm is critical towards the development of an enhanced behavioral and cognitive experience especially in conditions of CNS insults and the associated cognitive dysfunctions.

  4. Repeated nitrous oxide exposure in rats causes a thermoregulatory sign-reversal with concurrent activation of opposing thermoregulatory effectors

    PubMed Central

    Ramsay, Douglas S.; Woods, Stephen C.; Kaiyala, Karl J.

    2015-01-01

    Initial administration of 60% nitrous oxide (N2O) to rats at an ambient temperature of 21°C decreases core temperature (Tc), primarily via increased heat loss (HL). Over repeated N2O administrations, rats first develop tolerance to this hypothermia and subsequently exhibit hyperthermia (a sign-reversal) due primarily to progressive increases in heat production (HP). When rats initially receive 60% N2O in a thermal gradient, they become hypothermic while selecting cooler ambient temperatures that facilitate HL. This study investigated whether rats repeatedly administered 60% N2O in a thermal gradient would use the gradient to behaviorally facilitate, or oppose, the development of chronic tolerance and a hyperthermic sign-reversal. Male Long-Evans rats (N=16) received twelve 3-h administrations of 60% N2O in a gas-tight, live-in thermal gradient. Hypothermia (Sessions 1-3), complete chronic tolerance (Sessions 4-6), and a subsequent transient hyperthermic sign-reversal (Sessions 7-12) sequentially developed. Despite the progressive recovery and eventual hyperthermic sign-reversal of Tc, rats consistently selected cooler ambient temperatures during all N2O administrations. A final 60% N2O administration in a total calorimeter indicated that the hyperthermic sign-reversal resulted primarily from increased HP. Thus, rats did not facilitate chronic tolerance development by moving to warmer locations in the gradient, and instead selected cooler ambient temperatures while simultaneously increasing autonomic HP. The inefficient concurrent activation of opposing effectors and the development of a sign-reversal are incompatible with homeostatic models of drug-adaptation and may be better interpreted using a model of drug-induced allostasis. PMID:25938127

  5. Exposure to Hypoxia at High Altitude (5380 m) for 1 Year Induces Reversible Effects on Semen Quality and Serum Reproductive Hormone Levels in Young Male Adults.

    PubMed

    He, Jiang; Cui, Jianhua; Wang, Rui; Gao, Liang; Gao, Xiaokang; Yang, Liu; Zhang, Qiong; Cao, Jinjun; Yu, Wuzhong

    2015-09-01

    This study investigated the effect of hypoxia at high altitude on the semen quality and the serum reproductive hormone levels in male adults. A total of 52 male soldiers were enrolled in this cohort study. They were exposed to hypoxia at high altitude (5380 m) for 12 months when undergoing a service. After exposure, they were followed up for 6 months. The samples of semen and peripheral blood were collected at 1 month before exposure (M0), 6 months of exposure (M6), 12 months of exposure (M12), and 6 months after exposure (M18). The semen quality was assessed with computer-assisted analysis system, and the serum levels of reproductive hormones, including prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were analyzed by ELISA. Compared with those at M0, total sperm count, sperm density, motility, survival rate, and serum levels of LH, PRL and testosterone were significantly decreased, whereas the liquefaction time was significantly prolonged and serum FSH level was significantly increased at M6 (p<0.05). At M12, total sperm count and sperm density increased, whereas sperm motility, survival rate, and the liquefaction time further decreased. Sperm velocities, progression ratios, and lateral head displacements were also decreased. Serum FSH level decreased while serum LH, PRL, and testosterone levels increased. Compared with those at M6, the changes in these detected parameters of semen and hormone at M12 were significant (p<0.05). At M18, all these detected parameters except testosterone level returned to levels comparable to those before exposure. In conclusion, hypoxia at high altitude causes adverse effects on semen quality and reproductive hormones, and these effects are reversible.

  6. Phosphatidylserine Converts Immunogenic Recombinant Human Acid Alpha-Glucosidase to a Tolerogenic Form in a Mouse Model of Pompe Disease.

    PubMed

    Schneider, Jennifer L; Balu-Iyer, Sathy V

    2016-10-01

    Development of unwanted immune responses against therapeutic proteins is a major clinical complication. Recently, we have shown that exposure of Factor VIII in the presence of phosphatidylserine (PS) induces antigen-specific hyporesponsiveness to Factor VIII rechallenge, suggesting that PS is not immune suppressive, but rather immune regulatory in that PS converts an immunogen to a tolerogen. Since PS is exposed in the outer leaflet during apoptosis, we hypothesize that PS imparts tolerogenic activity to this natural process. Thus, immunization with PS containing liposomes would mimic this natural process. Here, we investigate the immune regulatory effects of PS in inducing tolerance toward recombinant human acid alpha-glucosidase (rhGAA). rhGAA was found to complex with PS liposomes through hydrophobic interactions, and incubation PS-rhGAA with dendritic cells resulted in the increased secretion of transforming growth factor-β. Immunization with PS-rhGAA or O-phospho-L-serine-rhGAA led to a reduction in anti-rhGAA antibody response which persisted despite rechallenge with free rhGAA. Importantly, the titer levels in a majority of these animals remained unchanged after rechallenge and can be considered nonresponders. These data provide evidence that PS liposomes can be used to induce tolerance toward therapeutic proteins, in general. PMID:27488899

  7. A lysine-rich motif in the phosphatidylserine receptor PSR-1 mediates recognition and removal of apoptotic cells

    PubMed Central

    Yang, Hengwen; Chen, Yu-Zen; Zhang, Yi; Wang, Xiaohui; Zhao, Xiang; Godfroy, James I.; Liang, Qian; Zhang, Man; Zhang, Tianying; Yuan, Quan; Royal, Mary Ann; Driscoll, Monica; Xia, Ning-Shao; Yin, Hang; Xue, Ding

    2014-01-01

    The conserved phosphatidylserine receptor (PSR) was first identified as a receptor for phosphatidylserine, an "eat-me" signal exposed by apoptotic cells. However, several studies suggest that PSR may also act as an arginine demethylase, a lysyl hydroxylase, or an RNA binding protein through its N-terminal JmjC domain. How PSR might execute drastically different biochemical activities, and whether they are physiologically significant, remain unclear. Here we report that a lysine-rich motif in the extracellular domain of PSR-1, the Caenorhabditis elegans PSR, mediates specific phosphatidylserine binding in vitro and clearance of apoptotic cells in vivo. This motif also mediates phosphatidylserine-induced oligomerization of PSR-1, suggesting a mechanism by which PSR-1 activates phagocytosis. Mutations in the phosphatidylserine-binding motif, but not in its Fe(II) binding site critical for the JmjC activity, abolish PSR-1 phagocytic function. Moreover, PSR-1 enriches and clusters around apoptotic cells during apoptosis. These results establish that PSR-1 is a conserved, phosphatidylserine-recognizing phagocyte receptor. PMID:25564762

  8. The Interaction of Melittin with Dimyristoyl Phosphatidylcholine-Dimyristoyl Phosphatidylserine Lipid Bilayer Membranes

    DOE PAGESBeta

    Rai, Durgesh K.; Qian, Shuo; Heller, William T.

    2016-08-13

    We report that membrane-active peptides (MAPs), which interact directly with the lipid bilayer of a cell and include toxins and host defense peptides, display lipid composition-dependent activity. Phosphatidylserine (PS) lipids are anionic lipids that are found throughout the cellular membranes of most eukaryotic organisms where they serve as both a functional component and as a precursor to phosphatidylethanolamine lipids. The inner leaflet of the plasma membrane contains more PS than the outer one, and the asymmetry is actively maintained. Here, the impact of the MAP melittin on the structure of lipid bilayer vesicles made of a mixture of phosphatidylcholine andmore » phosphatidylserine was studied. Small-angle neutron scattering of the MAP associated with selectively deuterium-labeled lipid bilayer vesicles revealed how the thickness and lipid composition of phosphatidylserine-containing vesicles change in response to melittin. The peptide thickens the lipid bilayer for concentrations up to P/L = 1/500, but membrane thinning results when P/L = 1/200. The thickness transition is accompanied by a large change in the distribution of DMPS between the leaflets of the bilayer. The change in composition is driven by electrostatic interactions, while the change in bilayer thickness is driven by changes in the interaction of the peptide with the headgroup region of the lipid bilayer. Lastly, the results provide new information about lipid-specific interactions that take place in mixed composition lipid bilayer membranes.« less

  9. Photoaffinity labeling of the Torpedo californica nicotinic acetylcholine receptor with an aryl azide derivative of phosphatidylserine

    SciTech Connect

    Blanton, M.P.; Wang, H.H. )

    1990-02-06

    A photoactivatable analogue of phosphatidylserine, {sup 125}I-labeled 4-azidosalicylic acid-phosphatidylserine ({sup 125}I ASA-PS), was used to label both native acetylcholine receptor (AchR)-rich membranes from Torpedo californica and AchR membranes affinity purified from Torpedo reconstituted into asolectin vesicles. The radioiodinated arylazido group attaches directly to the phospholipid head group and thus probes for regions of the AchR structure in contact with the negatively charged head group of phosphatidylserine. All four subunits of the AchR incorporated the label, with the {alpha} subunit incorporating approximately twice as much as each of the other subunits on a per mole basis. The regions of the AchR {alpha} subunit that incorporated {sup 125}I ASA-PS were mapped by Staphylococcus aureus V8 protease digestion. The majority of label incorporated into fragments representing a more complete digestion of the {alpha} subunit was localized to 11.7- and 10.1-kDa V8 cleavage fragments, both beginning at Asn-339 and of sufficient length to contain the hydrophobic region M4. An 18.7-kDa fragment beginning at Ser-173 and of sufficient length to contain the hydrophobic regions M1, M2, and M3 was also significantly labeled. In contrast, V8 cleavage fragments representing roughly a third of the amino-terminal portion of the {alpha} subunit incorporated little or no detectable amount of probe.

  10. Proteinase 3 Is a Phosphatidylserine-binding Protein That Affects the Production and Function of Microvesicles.

    PubMed

    Martin, Katherine R; Kantari-Mimoun, Chahrazade; Yin, Min; Pederzoli-Ribeil, Magali; Angelot-Delettre, Fanny; Ceroi, Adam; Grauffel, Cédric; Benhamou, Marc; Reuter, Nathalie; Saas, Philippe; Frachet, Philippe; Boulanger, Chantal M; Witko-Sarsat, Véronique

    2016-05-13

    Proteinase 3 (PR3), the autoantigen in granulomatosis with polyangiitis, is expressed at the plasma membrane of resting neutrophils, and this membrane expression increases during both activation and apoptosis. Using surface plasmon resonance and protein-lipid overlay assays, this study demonstrates that PR3 is a phosphatidylserine-binding protein and this interaction is dependent on the hydrophobic patch responsible for membrane anchorage. Molecular simulations suggest that PR3 interacts with phosphatidylserine via a small number of amino acids, which engage in long lasting interactions with the lipid heads. As phosphatidylserine is a major component of microvesicles (MVs), this study also examined the consequences of this interaction on MV production and function. PR3-expressing cells produced significantly fewer MVs during both activation and apoptosis, and this reduction was dependent on the ability of PR3 to associate with the membrane as mutating the hydrophobic patch restored MV production. Functionally, activation-evoked MVs from PR3-expressing cells induced a significantly larger respiratory burst in human neutrophils compared with control MVs. Conversely, MVs generated during apoptosis inhibited the basal respiratory burst in human neutrophils, and those generated from PR3-expressing cells hampered this inhibition. Given that membrane expression of PR3 is increased in patients with granulomatosis with polyangiitis, MVs generated from neutrophils expressing membrane PR3 may potentiate oxidative damage of endothelial cells and promote the systemic inflammation observed in this disease. PMID:26961880

  11. Formaldehyde-fixation of platelets for flow cytometric measurement of phosphatidylserine exposure is feasible.

    PubMed

    Rochat, Sophie; Alberio, Lorenzo

    2015-01-01

    Strong platelet activation results in a redistribution of negatively charged phospholipids from the cytosolic to the outer leaflet of the cellular membrane. Annexin V has a high affinity to negatively charged phospholipids and can be used to identify procoagulant platelets. Formaldehyde fixation can cause factitious Annexin V binding. Our aim was to evaluate a method for fixing platelets avoiding additional Annexin V binding. We induced expression of negatively charged phospholipids on the surface of a fraction of platelets by combined activation with convulxin and thrombin in the presence of Annexin V-fluorescein isothiocyanate and calcium. Aliquots of resting and activated platelets were fixed with a low concentration, calcium-free formaldehyde solution. Both native platelets and fixed platelets were analyzed by flow cytometry immediately and after a 24-h storage at 4°C. We observed that the percentage of Annexin V positive resting platelets ranged from 1.5 to 9.3% for the native samples and from 0.4 to 12.8% for the fixed samples (P=0.706, paired t-test). The amount of Annexin V positive convulxin/thrombin activated platelets varied from 12.9 to 35.4% without fixation and from 15.3 to 36.3% after formalin fixation (P=0.450). After a 24-h storage at 4°C, Annexin V positive platelets significantly increased both in the resting and in the convulxin/thrombin activated samples of native platelets (both P<0.001), while results for formalin fixed platelets did not differ from baseline values (P=0.318 for resting fixed platelets; P=0.673 for activated fixed platelets). We conclude that platelet fixation with a low concentration, calcium-free formaldehyde solution does not alter the proportion of Annexin V positive platelets. This method can be used to investigate properties of procoagulant platelets by multicolor flow-cytometric analysis requiring fixation steps.

  12. Developmental exposure of aflatoxin B1 reversibly affects hippocampal neurogenesis targeting late-stage neural progenitor cells through suppression of cholinergic signaling in rats.

    PubMed

    Tanaka, Takeshi; Mizukami, Sayaka; Hasegawa-Baba, Yasuko; Onda, Nobuhiko; Sugita-Konishi, Yoshiko; Yoshida, Toshinori; Shibutani, Makoto

    2015-10-01

    To elucidate the maternal exposure effects of aflatoxin B1 (AFB1) and its metabolite aflatoxin M1, which is transferred into milk, on postnatal hippocampal neurogenesis, pregnant Sprague-Dawley rats were provided a diet containing AFB1 at 0, 0.1, 0.3, or 1.0 ppm from gestational day 6 to day 21 after delivery on weaning. Offspring were maintained through postnatal day (PND) 77 without AFB1 exposure. Following exposure to 1.0 ppm AFB1, offspring showed no apparent systemic toxicity at weaning, whereas dams showed increased liver weight and DNA repair gene upregulation in the liver. In the hippocampal dentate gyrus of male PND 21 offspring, the number of doublecortin(+) progenitor cells were decreased, which was associated with decreased proliferative cell population in the subgranular zone at ≥ 0.3 ppm, although T-box brain 2(+) cells, tubulin beta III(+) cells, gamma-H2A histone family, member X(+) cells, and cyclin-dependent kinase inhibitor 1A(+) cells did not fluctuate in number. AFB1 exposure examined at 1.0 ppm also resulted in transcript downregulation of the cholinergic receptor subunit Chrna7 and dopaminergic receptor Drd2 in the dentate gyrus, although there was no change in transcript levels of DNA repair genes. In the hippocampal dentate hilus, interneurons expressing CHRNA7 or phosphorylated tropomyosin receptor kinase B (TRKB) decreased at ≥ 0.3 ppm. On PND 77, there were no changes in neurogenesis-related parameters. These results suggested that maternal AFB1 exposure reversibly affects hippocampal neurogenesis targeting type-3 progenitor cells. This mechanism likely involves suppression of cholinergic signals on hilar GABAergic interneurons and brain-derived neurotrophic factor-TRKB signaling from granule cells. The no-observed-adverse-effect level for offspring neurogenesis was determined to be 0.1 ppm (7.1-13.6 mg/kg body weight/day).

  13. A method for assessment of the genotoxicity of mainstream cigarette-smoke by use of the bacterial reverse-mutation assay and an aerosol-based exposure system.

    PubMed

    Kilford, Joanne; Thorne, David; Payne, Rebecca; Dalrymple, Annette; Clements, Julie; Meredith, Clive; Dillon, Debbie

    2014-07-15

    To date there are no widely accepted methods for the toxicological testing of complex gaseous mixtures and aerosols, such as cigarette smoke, although some modifications to the standard regulatory methods have been developed and used. Historically, routine testing of cigarettes has primarily focused on the particulate fraction of cigarette smoke. However, this fraction may not accurately reflect the full toxicity and mutagenicity of the smoke aerosol as a whole, which contains semi-volatiles and short-lived products of combustion. In this study we have used a modified version of the bacterial reverse-mutation (Ames) assay for the testing of mainstream smoke generated from 3R4F reference cigarettes with a Vitrocell(®) VC 10 exposure system. This method has been evaluated in four strains of Salmonella typhimurium (TA98, TA100, YG1024 and YG1042) and one strain of Escherichia coli (WP2 uvrA pKM101) in the absence and presence of a metabolic activation system. Following exposure at four concentrations of diluted mainstream cigarette-smoke, concentration-related and reproducible increases in the number of revertants were observed in all four Salmonella strains. E. coli strain WP2 uvrA pKM101 was unresponsive at the four concentrations tested. To quantify the exposure dose and to enable biological response to be plotted as a function of deposited mass, quartz-crystal microbalances were included in situ in the smoke-exposure set-up. This methodology was further assessed by comparing the responses of strain YG1042 to mainstream cigarette-smoke on a second VC 10 Smoking Robot. In summary, the Ames assay can be successfully modified to assess the toxicological impact of mainstream cigarette-smoke.

  14. Reversible aberration of neurogenesis affecting late-stage differentiation in the hippocampal dentate gyrus of rat offspring after maternal exposure to manganese chloride.

    PubMed

    Ohishi, Takumi; Wang, Liyun; Akane, Hirotoshi; Shiraki, Ayako; Goto, Ken; Ikarashi, Yoshiaki; Suzuki, Kazuhiko; Mitsumori, Kunitoshi; Shibutani, Makoto

    2012-11-01

    To examine the effects of developmental manganese (Mn)-exposure on hippocampal neurogenesis, pregnant rats were treated with MnCl(2)·4H(2)O in the diet at 32, 160 or 800 ppm from gestation day 10 to day 21 after delivery. Serum concentrations of thyroid-related hormones were examined in offspring exposed to MnCl(2)·4H(2)O at 800 or 1600 ppm. Immunohistochemical analysis revealed increased doublecortin-positive cells in the subgranular zone of the dentate gyrus on postnatal day (PND) 21 following exposure to MnCl(2)·4H(2)O at 800 ppm, indicating an increase of type-3 progenitor or immature granule cells. Reelin-positive cells, suggestive of γ-aminobutyric acid-ergic interneurons in the dentate hilus, also increased at 800 ppm on PND 21. Brain Mn concentrations increased in offspring on PND 21 at 160 and 800 ppm, whereas brain concentrations in the dams were unchanged. Serum concentrations of triiodothyronine and thyroxine decreased at 800 and 1600 ppm, whereas thyroid-stimulating hormone increased only after exposure at 800 ppm. All changes disappeared on PND 77. Thus, maternal exposure to MnCl(2)·4H(2)O at 800 ppm mildly and reversibly affects neurogenesis targeting late-stage differentiation in the hippocampal dentate gyrus of rat offspring. Direct effects of accumulated Mn in the developing brain might be implicated in the mechanism of the development of aberrations in neurogenesis; however, indirect effects through thyroid hormone fluctuations might be rather minor.

  15. Gallium arsenide exposure impairs processing of particulate antigen by macrophages: modification of the antigen reverses the functional defect.

    PubMed

    Hartmann, Constance B; McCoy, Kathleen L

    2004-06-11

    Gallium arsenide (GaAs), a semiconductor used in the electronics industry, causes systemic immunosuppression in animals. The chemical's impact on macrophages to process the particulate antigen, sheep red blood cells (SRBC), for a T cell response in culture was examined after in vivo exposure of mice. GaAs-exposed splenic macrophages were defective in activating SRBC-primed lymph node T cells that could not be attributed to impaired phagocytosis. Modified forms of SRBC were generated to examine the compromised function of GaAs-exposed macrophages. SRBC were fixed to maintain their particulate nature and subsequently delipidated with detergent. Delipidation of intact SRBC was insufficient to restore normal antigen processing in GaAs-exposed macrophages. However, chemically exposed cells efficiently processed soluble sheep proteins. These findings suggest that the problem may lie in the release of sequestered sheep protein antigens, which then could be effectively cleaved to peptides. Furthermore, opsonization of SRBC with IgG compensated for the macrophage processing defect. The influence of signal transduction and phagocytosis via Fcgamma receptors on improved antigen processing could be dissociated. Immobilized anti-Fcgamma receptor antibody activated macrophages to secrete a chemokine, but did not enhance processing of unmodified SRBC by GaAs-exposed macrophages. Restoration of normal processing of particulate SRBC by chemically exposed macrophages involved phagocytosis through Fcgamma receptors. Hence, initial immune responses may be very sensitive to GaAs exposure, and the chemical's immunosuppression may be averted by opsonized particulate antigens.

  16. Reversible oligohydramnios in the second trimester of pregnancy in two patients with long-term diclofenac exposure.

    PubMed

    Scherneck, Stephan; Schöpa, Franziska Lilli; Entezami, Michael; Kayser, Angela; Weber-Schoendorfer, Corinna; Schaefer, Christof

    2015-12-01

    The use of non-steroidal anti-inflammatory drugs like diclofenac in the third trimester of pregnancy can cause severe side effects, in particular oligohydramnios, premature closure of ductus arteriosus, and fetal kidney damage. However, the treatment with non-steroidal anti-inflammatory drugs until gestational week 28 is accepted as relatively safe. Here we describe two retrospectively reported cases of early-onset oligohydramnios associated with long-term diclofenac exposure of at least 150mg per day. The pathological findings were detected at gestational weeks 22 and 23, respectively. Amniotic fluid turned to normal after discontinuation of diclofenac in both cases, suggesting causality. Although early-onset oligohydramnios is a rare complication, caution for long-term diclofenac use in high doses is recommended even before gestational week 28.

  17. Live imaging of mitochondrial dynamics in CNS dopaminergic neurons in vivo demonstrates early reversal of mitochondrial transport following MPP(+) exposure.

    PubMed

    Dukes, April A; Bai, Qing; Van Laar, Victor S; Zhou, Yangzhong; Ilin, Vladimir; David, Christopher N; Agim, Zeynep S; Bonkowsky, Joshua L; Cannon, Jason R; Watkins, Simon C; Croix, Claudette M St; Burton, Edward A; Berman, Sarah B

    2016-11-01

    Extensive convergent evidence collectively suggests that mitochondrial dysfunction is central to the pathogenesis of Parkinson's disease (PD). Recently, changes in the dynamic properties of mitochondria have been increasingly implicated as a key proximate mechanism underlying neurodegeneration. However, studies have been limited by the lack of a model in which mitochondria can be imaged directly and dynamically in dopaminergic neurons of the intact vertebrate CNS. We generated transgenic zebrafish in which mitochondria of dopaminergic neurons are labeled with a fluorescent reporter, and optimized methods allowing direct intravital imaging of CNS dopaminergic axons and measurement of mitochondrial transport in vivo. The proportion of mitochondria undergoing axonal transport in dopaminergic neurons decreased overall during development between 2days post-fertilization (dpf) and 5dpf, at which point the major period of growth and synaptogenesis of the relevant axonal projections is complete. Exposure to 0.5-1.0mM MPP(+) between 4 and 5dpf did not compromise zebrafish viability or cause detectable changes in the number or morphology of dopaminergic neurons, motor function or monoaminergic neurochemistry. However, 0.5mM MPP(+) caused a 300% increase in retrograde mitochondrial transport and a 30% decrease in anterograde transport. In contrast, exposure to higher concentrations of MPP(+) caused an overall reduction in mitochondrial transport. This is the first time mitochondrial transport has been observed directly in CNS dopaminergic neurons of a living vertebrate and quantified in a PD model in vivo. Our findings are compatible with a model in which damage at presynaptic dopaminergic terminals causes an early compensatory increase in retrograde transport of compromised mitochondria for degradation in the cell body. These data are important because manipulation of early pathogenic mechanisms might be a valid therapeutic approach to PD. The novel transgenic lines and

  18. Live imaging of mitochondrial dynamics in CNS dopaminergic neurons in vivo demonstrates early reversal of mitochondrial transport following MPP(+) exposure.

    PubMed

    Dukes, April A; Bai, Qing; Van Laar, Victor S; Zhou, Yangzhong; Ilin, Vladimir; David, Christopher N; Agim, Zeynep S; Bonkowsky, Joshua L; Cannon, Jason R; Watkins, Simon C; Croix, Claudette M St; Burton, Edward A; Berman, Sarah B

    2016-11-01

    Extensive convergent evidence collectively suggests that mitochondrial dysfunction is central to the pathogenesis of Parkinson's disease (PD). Recently, changes in the dynamic properties of mitochondria have been increasingly implicated as a key proximate mechanism underlying neurodegeneration. However, studies have been limited by the lack of a model in which mitochondria can be imaged directly and dynamically in dopaminergic neurons of the intact vertebrate CNS. We generated transgenic zebrafish in which mitochondria of dopaminergic neurons are labeled with a fluorescent reporter, and optimized methods allowing direct intravital imaging of CNS dopaminergic axons and measurement of mitochondrial transport in vivo. The proportion of mitochondria undergoing axonal transport in dopaminergic neurons decreased overall during development between 2days post-fertilization (dpf) and 5dpf, at which point the major period of growth and synaptogenesis of the relevant axonal projections is complete. Exposure to 0.5-1.0mM MPP(+) between 4 and 5dpf did not compromise zebrafish viability or cause detectable changes in the number or morphology of dopaminergic neurons, motor function or monoaminergic neurochemistry. However, 0.5mM MPP(+) caused a 300% increase in retrograde mitochondrial transport and a 30% decrease in anterograde transport. In contrast, exposure to higher concentrations of MPP(+) caused an overall reduction in mitochondrial transport. This is the first time mitochondrial transport has been observed directly in CNS dopaminergic neurons of a living vertebrate and quantified in a PD model in vivo. Our findings are compatible with a model in which damage at presynaptic dopaminergic terminals causes an early compensatory increase in retrograde transport of compromised mitochondria for degradation in the cell body. These data are important because manipulation of early pathogenic mechanisms might be a valid therapeutic approach to PD. The novel transgenic lines and

  19. Contributions of phosphatidylserine-positive platelets and leukocytes and microparticles to hypercoagulable state in gastric cancer patients.

    PubMed

    Yang, Chunfa; Ma, Ruishuang; Jiang, Tao; Cao, Muhua; Zhao, Liangliang; Bi, Yayan; Kou, Junjie; Shi, Jialan; Zou, Xiaoming

    2016-06-01

    Hypercoagulability in gastric cancer is a common complication and a major contributor to poor prognosis. This study aimed to determine procoagulant activity of blood cells and microparticles (MPs) in gastric cancer patients. Phosphatidylserine-positive blood cells and MPs, and their procoagulant properties in particular, were assessed in 48 gastric cancer patients and 35 healthy controls. Phosphatidylserine-positive platelets, leukocytes, and MPs in patients with tumor-node-metastasis stage III/IV gastric cancer were significantly higher than those in stage I/II patients or healthy controls. Moreover, procoagulant activity of platelets, leukocytes, and MPs in stage III/IV patients was significantly increased compared to the controls, as indicated by shorter clotting time, higher intrinsic and extrinsic factor tenase, and prothrombinase complex activity. Interestingly, lactadherin, which competes with factors V and VIII to bind phosphatidylserine, dramatically prolonged clotting time of the cells and MPs by inhibiting factor tenase and prothrombinase complex activity. Although anti-tissue factor antibody significantly attenuated extrinsic tenase complex activity of leukocytes and MPs, it only slightly prolonged clotting times. Meanwhile, treatment with radical resection reduced phosphatidylserine-positive platelets, leukocytes, and MPs, and prolonged the clotting times of the remaining cells and MPs. Our results suggest that phosphatidylserine-positive platelets, leukocytes, and MPs contribute to hypercoagulability and represent a potential therapeutic target to prevent coagulation in patients with stage III/IV gastric cancer.

  20. Amelioration of scopolamine-induced amnesia by phosphatidylserine and curcumin in the day-old chick.

    PubMed

    Barber, Teresa A; Edris, Edward M; Levinsky, Paul J; Williams, Justin M; Brouwer, Ari R; Gessay, Shawn A

    2016-09-01

    In the one-trial taste-avoidance task in day-old chicks, acetylcholine receptor activation has been shown to be important for memory formation. Injection of scopolamine produces amnesia, which appears to be very similar in type to that of Alzheimer's disease, which is correlated with low levels of acetylcholine in the brain. Traditional pharmacological treatments of Alzheimer's disease, such as cholinesterase inhibitors and glutamate receptor blockers, improve memory and delay the onset of impairments in memory compared with placebo controls. These agents also ameliorate scopolamine-induced amnesia in the day-old chick trained on the one-trial taste-avoidance task. The present experiments examined the ability of two less traditional treatments for Alzheimer's disease, phosphatidylserine and curcumin, to ameliorate scopolamine-induced amnesia in day-old chicks. The results showed that 37.9 mmol/l phosphatidylserine and 2.7 mmol/l curcumin significantly improved retention in chicks administered scopolamine, whereas lower doses were not effective. Scopolamine did not produce state-dependent learning, indicating that this paradigm in day-old chicks might be a useful one to study the effects of possible Alzheimer's treatments. In addition, chicks administered curcumin or phosphatidylserine showed little avoidance of a bead associated with water reward, indicating that these drugs did not produce response inhibition. The current results extend the findings that some nontraditional memory enhancers can ameliorate memory impairment and support the hypothesis that these treatments might be of benefit in the treatment of Alzheimer's disease. PMID:27388114

  1. Cofactor-free detection of phosphatidylserine with cyclic peptides mimicking lactadherin.

    PubMed

    Zheng, Hong; Wang, Fang; Wang, Qin; Gao, Jianmin

    2011-10-01

    Cyclic peptides (cLacs) are designed to mimic the natural phosphatidylserine (PS) binding protein lactadherin. Unlike annexin V or its small molecule mimics, the cLac peptides selectively target PS-presenting membranes with no need for metal cofactors. We further show that a fluorophore-labeled cLac effectively stains early apoptotic cells. The small size and facile conjugation with a variety of imaging tracers make the cLac design promising for imaging cell death in vitro as well as in living organisms.

  2. The effect of chemical warfare on respiratory symptoms, pulmonary function tests and their reversibility 23-25 years after exposure.

    PubMed

    Boskabady, Mrteza; Boskabady, Mohammad Hossein; Zabihi, Narges Amel; Boskabady, Marzie

    2015-01-01

    Pulmonary complications due to mustard gas exposure range from no effect to severe bronchial stenosis. Pulmonary function tests (PFTs) and respiratory symptoms in chemical war victims were studied 23-25 years after exposure to sulfur mustard (SM). Respiratory symptoms were evaluated in a sample of 142 chemical war victims and 120 control subjects with similar age from the general population using a questionnaire including questions on respiratory symptoms in the past year. PFT values were also measured in chemical war victims before and 15 min after the inhalation of 200 µg salbutamol and baseline PFT in controls. All chemical war victims (100%) reported respiratory symptoms. Wheezing (66.19%), cough (64.78%), and chest tightness (54.4%) were the most common symptoms and only 15.5% of chemical war victims reported sputum (p < 0.01 for sputum and p < 0.001 for other symptoms compared with control group). In addition, 49.3% of chemical war victims had wheeze in chest examination, which were significantly higher than control group (p < 0.001). The severity of respiratory symptoms was also significantly higher than control subjects (p < 0.05 for sputum and p < 0.001 for other symptoms). All the PFT values were also significantly lower in chemical war victims than that in control subjects (p < 0.001 for all cases). In addition, all the PFT values improved significantly after the inhalation of 200 µg salbutamol (p < 0.05-p < 0.001). These results showed that chemical war victims, 23-25 years after exposure to chemical warfare have higher frequencies and severity of respiratory symptoms. PFT values were also significantly reduced among chemical war victims, which showed reversibility due to the inhalation of 200 µg salbutamol.

  3. Reversal of Refractory Ulcerative Colitis and Severe Chronic Fatigue Syndrome Symptoms Arising from Immune Disturbance in an HLADR/DQ Genetically Susceptible Individual with Multiple Biotoxin Exposures

    PubMed Central

    Gunn, Shelly R.; Gibson Gunn, G.; Mueller, Francis W.

    2016-01-01

    Patient: Male, 25 Final Diagnosis: Ulcerative colitis and chronic fatigue syndrome Symptoms: Colitis • profound fatigue • multi-joint pain • cognitive impairment • corneal keratitis Medication: — Clinical Procedure: VIP replacement therapy Specialty: Family Medicine Objective: Unusual clinical course Background: Patients with multisymptom chronic conditions, such as refractory ulcerative colitis (RUC) and chronic fatigue syndrome (CFS), present diagnostic and management challenges for clinicians, as well as the opportunity to recognize and treat emerging disease entities. In the current case we report reversal of co-existing RUC and CFS symptoms arising from biotoxin exposures in a genetically susceptible individual. Case Report: A 25-year-old previously healthy male with new-onset refractory ulcerative colitis (RUC) and chronic fatigue syndrome (CFS) tested negative for autoimmune disease biomarkers. However, urine mycotoxin panel testing was positive for trichothecene group and air filter testing from the patient’s water-damaged rental house identified the toxic mold Stachybotrys chartarum. HLA-DR/DQ testing revealed a multisusceptible haplotype for development of chronic inflammation, and serum chronic inflammatory response syndrome (CIRS) biomarker testing was positive for highly elevated TGF-beta and a clinically undetectable level of vasoactive intestinal peptide (VIP). Following elimination of biotoxin exposures, VIP replacement therapy, dental extractions, and implementation of a mind body intervention-relaxation response (MBI-RR) program, the patient’s symptoms resolved. He is off medications, back to work, and resuming normal exercise. Conclusions: This constellation of RUC and CFS symptoms in an HLA-DR/DQ genetically susceptible individual with biotoxin exposures is consistent with the recently described CIRS disease pathophysiology. Chronic immune disturbance (turbatio immuno) can be identified with clinically available CIRS biomarkers and

  4. The Role of Putative Phosphatidylserine-Interactive Residues of Tissue Factor on Its Coagulant Activity at the Cell Surface

    PubMed Central

    Ansari, Shabbir A.; Pendurthi, Usha R.; Sen, Prosenjit; Rao, L. Vijaya Mohan

    2016-01-01

    Exposure of phosphatidylserine (PS) on the outer leaflet of the cell membrane is thought to play a critical role in tissue factor (TF) decryption. Recent molecular dynamics simulation studies suggested that the TF ectodomain may directly interact with PS. To investigate the potential role of TF direct interaction with the cell surface phospholipids on basal TF activity and the enhanced TF activity following the decryption, one or all of the putative PS-interactive residues in the TF ectodomain were mutated and tested for their coagulant activity in cell systems. Out of the 9 selected TF mutants, five of them -TFS160A, TFS161A, TFS162A, TFK165A, and TFD180A- exhibited a similar TF coagulant activity to that of the wild-type TF. The specific activity of three mutants, TFK159A, TFS163A, and TFK166A, was reduced substantially. Mutation of the glycine residue at the position 164 markedly abrogated the TF coagulant activity, resulting in ~90% inhibition. Mutation of all nine lipid binding residues together did not further decrease the activity of TF compared to TFG164A. A similar fold increase in TF activity was observed in wild-type TF and all TF mutants following the treatment of THP-1 cells with either calcium ionomycin or HgCl2, two agents that are commonly used to decrypt TF. Overall, our data show that a few select TF residues that are implicated in interacting with PS contribute to the TF coagulant activity at the cell surface. However, our data also indicate that TF regions outside of the putative lipid binding region may also contribute to PS-dependent decryption of TF. PMID:27348126

  5. An extensive cocktail approach for rapid risk assessment of in vitro CYP450 direct reversible inhibition by xenobiotic exposure.

    PubMed

    Spaggiari, Dany; Daali, Youssef; Rudaz, Serge

    2016-07-01

    Acute exposure to environmental factors strongly affects the metabolic activity of cytochrome P450 (P450). As a consequence, the risk of interaction could be increased, modifying the clinical outcomes of a medication. Because toxic agents cannot be administered to humans for ethical reasons, in vitro approaches are therefore essential to evaluate their impact on P450 activities. In this work, an extensive cocktail mixture was developed and validated for in vitro P450 inhibition studies using human liver microsomes (HLM). The cocktail comprised eleven P450-specific probe substrates to simultaneously assess the activities of the following isoforms: 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 2J2 and subfamily 3A. The high selectivity and sensitivity of the developed UHPLC-MS/MS method were critical for the success of this methodology, whose main advantages are: (i) the use of eleven probe substrates with minimized interactions, (ii) a low HLM concentration, (iii) fast incubation (5min) and (iv) the use of metabolic ratios as microsomal P450 activities markers. This cocktail approach was successfully validated by comparing the obtained IC50 values for model inhibitors with those generated with the conventional single probe methods. Accordingly, reliable inhibition values could be generated 10-fold faster using a 10-fold smaller amount of HLM compared to individual assays. This approach was applied to assess the P450 inhibition potential of widespread insecticides, namely, chlorpyrifos, fenitrothion, methylparathion and profenofos. In all cases, P450 2B6 was the most affected with IC50 values in the nanomolar range. For the first time, mixtures of these four insecticides incubated at low concentrations showed a cumulative inhibitory in vitro effect on P450 2B6. PMID:27105555

  6. Characterization of Plasmodium phosphatidylserine decarboxylase expressed in yeast and application for inhibitor screening

    PubMed Central

    Choi, Jae-Yeon; Lawres, Lauren; Toh, Justin Y.; Voelker, Dennis R.; Ben Mamoun, Choukri

    2016-01-01

    Summary Phospholipid biosynthesis is critical for the development, differentiation and pathogenesis of several eukaryotic pathogens. Genetic studies have validated the pathway for phosphatidylethanolamine synthesis from phosphatidylserine catalyzed by phosphatidylserine decarboxylase enzymes (PSD) as a suitable target for development of antimicrobials; however no inhibitors of this class of enzymes have been discovered. We show that the Plasmodium falciparum PSD can restore the essential function of the yeast gene in strains requiring PSD for growth. Genetic, biochemical and metabolic analyses demonstrate that amino acids between positions 40 and 70 of the parasite enzyme are critical for proenzyme processing and decarboxylase activity. We used the essential role of Plasmodium PSD in yeast as a tool for screening a library of anti-malarials. One of these compounds is 7-chloro-N-(4-ethoxyphenyl)-4-quinolinamine, an inhibitor with potent activity against P. falciparum, and low toxicity toward mammalian cells. We synthesized an analog of this compound and showed that it inhibits PfPSD activity and eliminates Plasmodium yoelii infection in mice. These results highlight the importance of 4-quinolinamines as a novel class of drugs targeting membrane biogenesis via inhibition of PSD activity PMID:26585333

  7. Complementary probes reveal that phosphatidylserine is required for the proper transbilayer distribution of cholesterol.

    PubMed

    Maekawa, Masashi; Fairn, Gregory D

    2015-04-01

    Cholesterol is an essential component of metazoan cellular membranes and it helps to maintain the structural integrity and fluidity of the plasma membrane. Here, we developed a cholesterol biosensor, termed D4H, based on the fourth domain of Clostridium perfringens theta-toxin, which recognizes cholesterol in the cytosolic leaflet of the plasma membrane and organelles. The D4H probe disassociates from the plasma membrane upon cholesterol extraction and after perturbations in cellular cholesterol trafficking. When used in combination with a recombinant version of the biosensor, we show that plasmalemmal phosphatidylserine is essential for retaining cholesterol in the cytosolic leaflet of the plasma membrane. In vitro experiments reveal that 1-stearoy-2-oleoyl phosphatidylserine can induce phase separation in cholesterol-containing lipid bilayers and shield cholesterol from cholesterol oxidase. Finally, the altered transbilayer distribution of cholesterol causes flotillin-1 to relocalize to endocytic organelles. This probe should be useful in the future to study pools of cholesterol in the cytosolic leaflet of the plasma membrane and organelles. PMID:25663704

  8. The Molecular Structure of a Phosphatidylserine Bilayer Determined by Scattering and Molecular Dynamics Simulations

    SciTech Connect

    Pan, Jianjun; Cheng, Xiaolin; Monticelli, Luca; Heberle, Frederick A; Kucerka, Norbert; Tieleman, D. Peter; Katsaras, John

    2014-01-01

    Phosphatidylserine (PS) lipids play essential roles in biological processes, including enzyme activation and apoptosis. We report on the molecular structure and atomic scale interactions of a fluid bilayer composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine (POPS). A scattering density profile model, aided by molecular dynamics (MD) simulations, was developed to jointly refine different contrast small-angle neutron and X-ray scattering data, which yielded a lipid area of 62.7 A2 at 25 C. MD simulations with POPS lipid area constrained at different values were also performed using all-atom and aliphatic united-atom models. The optimal simulated bilayer was obtained using a model-free comparison approach. Examination of the simulated bilayer, which agrees best with the experimental scattering data, reveals a preferential interaction between Na+ ions and the terminal serine and phosphate moieties. Long-range inter-lipid interactions were identified, primarily between the positively charged ammonium, and the negatively charged carboxylic and phosphate oxygens. The area compressibility modulus KA of the POPS bilayer was derived by quantifying lipid area as a function of surface tension from area-constrained MD simulations. It was found that POPS bilayers possess a much larger KA than that of neutral phosphatidylcholine lipid bilayers. We propose that the unique molecular features of POPS bilayers may play an important role in certain physiological functions.

  9. Complementary probes reveal that phosphatidylserine is required for the proper transbilayer distribution of cholesterol.

    PubMed

    Maekawa, Masashi; Fairn, Gregory D

    2015-04-01

    Cholesterol is an essential component of metazoan cellular membranes and it helps to maintain the structural integrity and fluidity of the plasma membrane. Here, we developed a cholesterol biosensor, termed D4H, based on the fourth domain of Clostridium perfringens theta-toxin, which recognizes cholesterol in the cytosolic leaflet of the plasma membrane and organelles. The D4H probe disassociates from the plasma membrane upon cholesterol extraction and after perturbations in cellular cholesterol trafficking. When used in combination with a recombinant version of the biosensor, we show that plasmalemmal phosphatidylserine is essential for retaining cholesterol in the cytosolic leaflet of the plasma membrane. In vitro experiments reveal that 1-stearoy-2-oleoyl phosphatidylserine can induce phase separation in cholesterol-containing lipid bilayers and shield cholesterol from cholesterol oxidase. Finally, the altered transbilayer distribution of cholesterol causes flotillin-1 to relocalize to endocytic organelles. This probe should be useful in the future to study pools of cholesterol in the cytosolic leaflet of the plasma membrane and organelles.

  10. Human rhinovirus-induced inflammatory responses are inhibited by phosphatidylserine containing liposomes

    PubMed Central

    Stokes, C A; Kaur, R; Edwards, M R; Mondhe, M; Robinson, D; Prestwich, E C; Hume, R D; Marshall, C A; Perrie, Y; O'Donnell, V B; Harwood, J L; Sabroe, I; Parker, L C

    2016-01-01

    Human rhinovirus (HRV) infections are major contributors to the healthcare burden associated with acute exacerbations of chronic airway disease, such as chronic obstructive pulmonary disease and asthma. Cellular responses to HRV are mediated through pattern recognition receptors that may in part signal from membrane microdomains. We previously found Toll-like receptor signaling is reduced, by targeting membrane microdomains with a specific liposomal phosphatidylserine species, 1-stearoyl-2-arachidonoyl-sn-glycero-3-phospho-L-serine (SAPS). Here we explored the ability of this approach to target a clinically important pathogen. We determined the biochemical and biophysical properties and stability of SAPS liposomes and studied their ability to modulate rhinovirus-induced inflammation, measured by cytokine production, and rhinovirus replication in both immortalized and normal primary bronchial epithelial cells. SAPS liposomes rapidly partitioned throughout the plasma membrane and internal cellular membranes of epithelial cells. Uptake of liposomes did not cause cell death, but was associated with markedly reduced inflammatory responses to rhinovirus, at the expense of only modest non-significant increases in viral replication, and without impairment of interferon receptor signaling. Thus using liposomes of phosphatidylserine to target membrane microdomains is a feasible mechanism for modulating rhinovirus-induced signaling, and potentially a prototypic new therapy for viral-mediated inflammation. PMID:26906404

  11. Phosphatidylserine Synthase Controls Cell Elongation Especially in the Uppermost Internode in Rice by Regulation of Exocytosis

    PubMed Central

    Chen, Jun; Shen, Jinbo; Zhang, Baocai; Ren, Yulong; Ding, Yu; Zhou, Yihua; Zhang, Huan; Zhou, Kunneng; Wang, Jiu-Lin; Lei, Cailin; Zhang, Xin; Guo, Xiuping; Gao, He; Bao, Yiqun; Wan, Jian-Min

    2016-01-01

    The uppermost internode is one of the fastest elongating organs in rice, and is expected to require an adequate supply of cell-wall materials and enzymes to the cell surface to enhance mechanical strength. Although it has been reported that the phenotype of shortened uppermost internode 1 (sui1) is caused by mutations in PHOSPHATIDYLSERINE SYNTHASE (OsPSS), the underlying mechanism remains unclear. Here we show that the OsPSS-1, as a gene expressed predominantly in elongating cells, regulates post-Golgi vesicle secretion to intercellular spaces. Mutation of OsPSS-1 leads to compromised delivery of CESA4 and secGFP towards the cell surface, resulting in weakened intercellular adhesion and disorganized cell arrangement in parenchyma. The phenotype of sui1-4 is caused largely by the reduction in cellulose contents in the whole plant and detrimental delivery of pectins in the uppermost internode. We found that OsPSS-1 and its potential product PS (phosphatidylserine) localized to organelles associated with exocytosis. These results together suggest that OsPSS-1 plays a potential role in mediating cell expansion by regulating secretion of cell wall components. PMID:27055010

  12. Prenatal Ethanol Exposure Increases Brain Cholesterol Content in Adult Rats

    PubMed Central

    Barceló-Coblijn, Gwendolyn; Wold, Loren E.; Ren, Jun; Murphy, Eric J.

    2013-01-01

    Fetal alcohol syndrome is the most severe expression of the fetal alcohol spectrum disorders (FASD). Although alterations in fetal and neonate brain fatty acid composition and cholesterol content is known to change in animal models of FASD, the persistence of these alterations into adulthood is unknown. To address this question, we determined the effect of prenatal ethanol exposure on individual phospholipid class fatty acid composition, individual phospholipid class mass, and cholesterol mass in brains from 25-week-old rats that were exposed to ethanol during gestation beginning at gestational day 2. While total phospholipid mass was unaffected, phosphatidylinositol and cardiolipin mass was decreased 14 and 43%, respectively. Exposure to prenatal ethanol modestly altered brain phospholipid fatty acid composition, and the most consistent change was a significant 1.1-fold increase in total PUFA, in the n-3/n-6 ratio, and in the 22:6 n-3 content in ethanolamine glycerophospholipids and in phosphatidylserine. In contrast, prenatal ethanol consumption significantly increased brain cholesterol mass 1.4-fold and the phospholipid to cholesterol ratio was significantly increased 1.3-fold. These results indicate that brain cholesterol mass was significantly increased in adult rats exposed prenatally to ethanol, but changes in phospholipid mass and phospholipid fatty acid composition were extremely limited. Importantly, suppression of post-natal ethanol consumption was not sufficient to reverse the large increase in cholesterol observed in the adult rats. PMID:23996454

  13. Developmental exposure to T-2 toxin reversibly affects postnatal hippocampal neurogenesis and reduces neural stem cells and progenitor cells in mice.

    PubMed

    Tanaka, Takeshi; Abe, Hajime; Kimura, Masayuki; Onda, Nobuhiko; Mizukami, Sayaka; Yoshida, Toshinori; Shibutani, Makoto

    2016-08-01

    To determine the developmental exposure effects of T-2 toxin on postnatal hippocampal neurogenesis, pregnant ICR mice were provided a diet containing T-2 toxin at 0, 1, 3, or 9 ppm from gestation day 6 to day 21 on weaning after delivery. Offspring were maintained through postnatal day (PND) 77 without T-2 toxin exposure. In the hippocampal dentate gyrus of male PND 21 offspring, GFAP(+) and BLBP(+) type-1 stem cells and PAX6(+) and TBR2(+) type-2 progenitor cells decreased in the subgranular zone (SGZ) at 9 and ≥3 ppm, respectively, in parallel with increased apoptosis at ≥3 ppm. In the dentate hilus, reelin(+) γ-aminobutyric acid (GABA)-ergic interneurons increased at 9 ppm, suggesting reflection of neuronal mismigration. T-2 toxin decreased transcript levels of cholinergic and glutamate receptor subunits (Chrna4, Chrnb2 and Gria2) and glutamate transporter (Slc17a6) in the dentate gyrus, suggesting decreased cholinergic signals on hilar GABAergic interneurons innervating type-2 cells and decreased glutamatergic signals on type-1 and type-2 cells. T-2 toxin decreased SGZ cells expressing stem cell factor (SCF) and increased cells accumulating malondialdehydes. Neurogenesis-related changes disappeared on PND 77, suggesting that T-2 toxin reversibly affects neurogenesis by inducing apoptosis of type-1 and type-2 cells with different threshold levels. Decreased cholinergic and glutamatergic signals may decrease type-2 cells at ≥3 ppm. Additionally, decreased SCF/c-Kit interactions and increased oxidative stress may decrease type-1 and type-2 cells at 9 ppm. The no-observed-adverse-effect level for offspring neurogenesis was determined to be 1 ppm (0.14-0.49 mg/kg body weight/day).

  14. Enhancement of cancer stem-like and epithelial−mesenchymal transdifferentiation property in oral epithelial cells with long-term nicotine exposure: Reversal by targeting SNAIL

    SciTech Connect

    Yu, Cheng-Chia; Chang, Yu-Chao

    2013-02-01

    Cigarette smoking is one of the major risk factors in the development and further progression of tumorigenesis, including oral squamous cell carcinoma (OSCC). Recent studies suggest that interplay cancer stem-like cells (CSCs) and epithelial−mesenchymal transdifferentiation (EMT) properties are responsible for the tumor maintenance and metastasis in OSCC. The aim of the present study was to investigate the effects of long-term exposure with nicotine, a major component in cigarette, on CSCs and EMT characteristics. The possible reversal regulators were further explored in nicotine-induced CSCs and EMT properties in human oral epithelial (OE) cells. Long-term exposure with nicotine was demonstrated to up-regulate ALDH1 population in normal gingival and primary OSCC OE cells dose-dependently. Moreover, long-term nicotine treatment was found to enhance the self-renewal sphere-forming ability and stemness gene signatures expression and EMT regulators in OE cells. The migration/cell invasiveness/anchorage independent growth and in vivo tumor growth by nude mice xenotransplantation assay was enhanced in long-term nicotine-stimulated OE cells. Knockdown of Snail in long-term nicotine-treated OE cells was found to reduce their CSCs properties. Therapeutic delivery of Si-Snail significantly blocked the xenograft tumorigenesis of long-term nicotine-treated OSCC cells and largely significantly improved the recipient survival. The present study demonstrated that the enrichment of CSCs coupled EMT property in oral epithelial cells induced by nicotine is critical for the development of OSCC tumorigenesis. Targeting Snail might offer a new strategy for the treatment of OSCC patients with smoking habit. -- Highlights: ► Sustained nicotine treatment induced CSCs properties of oral epithelial cells. ► Long-term nicotine treatment enhance EMT properties of oral epithelial cells. ► Long-term nicotine exposure increased tumorigenicity of oral epithelial cells. ► Si

  15. Suppression of atopic dermatitis in mice model by reducing inflammation utilizing phosphatidylserine-coated biodegradable microparticles.

    PubMed

    Kumar, Purnima; Hosain, Md Zahangir; Kang, Jeong-Hun; Takeo, Masafumi; Kishimura, Akihiro; Mori, Takeshi; Katayama, Yoshiki

    2015-01-01

    Controlling inflammatory response is important to avoid chronic inflammation in many diseases including atopic dermatitis (AD). In this research, we tried using a phosphatidylserine (PS)-coated microparticles in the AD mouse model for achieving the modulation of the macrophage phenotype to an anti-inflammatory state. Here, we prepared poly (D,L-lactic acid) microparticle coated with PS on the outside shell. We confirmed the cellular uptake of the PS-coated microparticle, which leads to the significant downregulation of the inflammatory cytokine production. In the mouse model of AD, the PS-coated microparticle was injected subcutaneously for a period of 12 days. The mice showed significant reduction in the development of AD symptoms comparing with the mice treated with the PC-coated microparticle. PMID:26414796

  16. Involvement of VAT-1 in Phosphatidylserine Transfer from the Endoplasmic Reticulum to Mitochondria.

    PubMed

    Junker, Mirco; Rapoport, Tom A

    2015-12-01

    Mitochondria receive phosphatidylserine (PS) from the endoplasmic reticulum (ER), but how PS is moved from the ER to mitochondria is unclear. Current models postulate a physical link between the organelles, but no involvement of cytosolic proteins. Here, we have reconstituted PS transport from the ER to mitochondria in vitro using Xenopus egg components. Transport is independent of ER proteins, but is dependent on a cytosolic factor that has a preferential affinity for PS. Crosslinking with a photoactivatable PS analog identified VAT-1 as a candidate for a cytosolic PS transport protein. Recombinant, purified VAT-1 stimulated PS transport into mitochondria and depletion of VAT-1 from Xenopus cytosol with specific antibodies led to a reduction of transport. Our results suggest that cytosolic factors have a role in PS transport from the ER to mitochondria, implicate VAT-1 in the transport process, and indicate that physical contact between the organelles is not essential.

  17. The TAM family: phosphatidylserine sensing receptor tyrosine kinases gone awry in cancer.

    PubMed

    Graham, Douglas K; DeRyckere, Deborah; Davies, Kurtis D; Earp, H Shelton

    2014-12-01

    The TYRO3, AXL (also known as UFO) and MERTK (TAM) family of receptor tyrosine kinases (RTKs) are aberrantly expressed in multiple haematological and epithelial malignancies. Rather than functioning as oncogenic drivers, their induction in tumour cells predominately promotes survival, chemoresistance and motility. The unique mode of maximal activation of this RTK family requires an extracellular lipid–protein complex. For example, the protein ligand, growth arrest-specific protein 6 (GAS6), binds to phosphatidylserine (PtdSer) that is externalized on apoptotic cell membranes, which activates MERTK on macrophages. This triggers engulfment of apoptotic material and subsequent anti-inflammatory macrophage polarization. In tumours, autocrine and paracrine ligands and apoptotic cells are abundant, which provide a survival signal to the tumour cell and favour an anti-inflammatory, immunosuppressive microenvironment. Thus, TAM kinase inhibition could stimulate antitumour immunity, reduce tumour cell survival, enhance chemosensitivity and diminish metastatic potential. PMID:25568918

  18. Room temperature ordering of dipalmitoyl phosphatidylserine bilayers induced by short chain alcohols.

    PubMed

    Wachtel, E; Bach, D; Miller, I R

    2013-01-01

    Using differential scanning calorimetry and small and wide angle X-ray diffraction, we show that, following extended incubation at room temperature, methanol, propanol, and three of the isomers of butanol can induce ordering in dipalmitoyl phosphatidylserine (DPPS) gel phase bilayers. The organization of the bilayers in the presence of ethanol, described previously, is now observed to be a general effect of short chain alcohols. Evidence is presented for tilting of the acyl chains with respect to the bilayer normal in the presence of ethanol or propanol. However, the different chain lengths of the alcohols, and isomeric form, influence the thermal stability of the ordered gel to different extents. This behavior is unlike that of the gel state phosphatidylcholine analog which, in the presence of short chain alcohols, undergoes hydrocarbon chain interdigitation. Dipalmitoyl phosphatidylcholine added to DPPS in the presence of 20 vol% ethanol, acts to suppress the ordered gel phase.

  19. TIM-4 structures identify a Metal Ion-dependent Ligand Binding Site where phosphatidylserine binds

    PubMed Central

    Santiago, Cesar; Ballesteros, Angela; Martinez-Muñoz, Laura; Mellado, Mario; Kaplan, Gerardo G.; Freeman, Gordon J.; Casasnovas, José M.

    2008-01-01

    The T-cell immunoglobulin and mucin domain (TIM) proteins are important regulators of T cell responses. They have been linked to autoimmunity and cancer. Structures of the murine TIM-4 identified a Metal Ion-dependent Ligand Binding Site (MILIBS) in the immunoglobulin (Ig) domain of the TIM family. The characteristic CC’ loop of the TIM domain and the hydrophobic FG loop shaped a narrow cavity where acidic compounds penetrate and coordinate to a metal ion bound to conserved residues in the TIM proteins. The structure of phosphatidylserine bound to the Ig domain showed that the hydrophilic head penetrates into the MILIBS and coordinates with the metal ion, while the aromatic residues on the tip of the FG loop interacted with the fatty acid chains and could insert into the lipid bilayer. Our results also revealed a significant role of the MILIBS in trafficking of TIM-1 to the cell surface. PMID:18083575

  20. The TAM family: phosphatidylserine sensing receptor tyrosine kinases gone awry in cancer.

    PubMed

    Graham, Douglas K; DeRyckere, Deborah; Davies, Kurtis D; Earp, H Shelton

    2014-12-01

    The TYRO3, AXL (also known as UFO) and MERTK (TAM) family of receptor tyrosine kinases (RTKs) are aberrantly expressed in multiple haematological and epithelial malignancies. Rather than functioning as oncogenic drivers, their induction in tumour cells predominately promotes survival, chemoresistance and motility. The unique mode of maximal activation of this RTK family requires an extracellular lipid–protein complex. For example, the protein ligand, growth arrest-specific protein 6 (GAS6), binds to phosphatidylserine (PtdSer) that is externalized on apoptotic cell membranes, which activates MERTK on macrophages. This triggers engulfment of apoptotic material and subsequent anti-inflammatory macrophage polarization. In tumours, autocrine and paracrine ligands and apoptotic cells are abundant, which provide a survival signal to the tumour cell and favour an anti-inflammatory, immunosuppressive microenvironment. Thus, TAM kinase inhibition could stimulate antitumour immunity, reduce tumour cell survival, enhance chemosensitivity and diminish metastatic potential.

  1. Antibodies to phosphatidylserine/prothrombin complex as an additional diagnostic marker of APS?

    PubMed

    Žigon, P; Čučnik, S; Ambrožič, A; Sodin Šemrl, S; Kveder, T; Božič, B

    2012-06-01

    Antiprothrombin antibodies can be measured by ELISA using either a prothrombin/phosphatidylserine complex (aPS/PT) or prothrombin alone (aPT) as antigen. We aimed to compare the clinical features of autoimmune patients with avidity of aPS/PT and determine the diagnostic efficiency of aPS/PT and aPT for assessing antiphospholipid syndrome (APS). aPS/PT were of low (n = 9), heterogeneous (n = 31) and high (n = 8) avidity out of 48 cases. None of the samples with low avidity were positive in aPT ELISA. Among patients with heterogeneous or high avidity aPS/PT, there was a significantly greater number of patients with APS as compared to patients with low avidity (38/39 vs. 7/9; p < 0.05). No SLE patients had high avidity antiprothrombin antibodies.

  2. The intrinsic pKa values for phosphatidylserine and phosphatidylethanolamine in phosphatidylcholine host bilayers.

    PubMed Central

    Tsui, F C; Ojcius, D M; Hubbell, W L

    1986-01-01

    Potentiometric titrations and surface potential measurements have been used to determine the intrinsic pKa values of both the carboxyl and amino groups of phosphatidylserine (PS) in mixed vesicles of PS and phosphatidylcholine (PC), and also of the amino group of phosphatidylethanolamine (PE) in mixed PE-PC vesicles. The pKa of the carboxyl group of PS in liposomes with different PS/PC lipid ratios measured by the two different methods is 3.6 +/- 0.1, and the pKa of its amino group is 9.8 +/- 0.1. The pKa of the amino group of PE in PE-PC vesicles, determined solely by surface potential measurements, is 9.6 +/- 0.1. These pKa values are independent of the aqueous phase ionic strength and of the effect of the liposome's surface potential due to the presence of these partially charged lipids. PMID:3955180

  3. Inhibition of Rho-ROCK signaling induces apoptotic and non-apoptotic PS exposure in cardiomyocytes via inhibition of flippase.

    PubMed

    Krijnen, Paul A J; Sipkens, Jessica A; Molling, Johan W; Rauwerda, Jan A; Stehouwer, Coen D A; Muller, Alice; Paulus, Walter J; van Nieuw Amerongen, Geerten P; Hack, C Erik; Verhoeven, Arthur J; van Hinsbergh, Victor W M; Niessen, Hans W M

    2010-11-01

    Subsequent to myocardial infarction, cardiomyocytes within the infarcted areas and border zones expose phosphatidylserine (PS) in the outer plasma membrane leaflet (flip-flop). We showed earlier that in addition to apoptosis, this flip-flop can be reversible in cardiomyocytes. We now investigated a possible role for Rho and downstream effector Rho-associated kinase (ROCK) in the process of (reversible) PS exposure and apoptosis in cardiomyocytes. In rat cardiomyoblasts (H9c2 cells) and isolated adult ventricular rat cardiomyocytes Clostridium difficile Toxin B (TcdB), a Rho GTPase family inhibitor, C3 transferase (C3), a Rho(A,B,C) inhibitor and the ROCK inhibitors Y27632 and H1152 were used to inhibit Rho-ROCK signaling. PS exposure was assessed via flow cytometry and fluorescent digital imaging microscopy using annexin V. Akt expression and phosphorylation were analyzed via Western blot, and Akt activity was inhibited by wortmannin. The cellular concentration activated caspase 3 was determined as a measure of apoptosis, and flippase activity was assessed via flow cytometry using NBD-labeled PS. TcdB, C3, Y27632 and H1152 all significantly increased PS exposure. TcdB, Y27632 and H1152 all significantly inhibited phosphorylation of the anti-apoptotic protein Akt and Akt inhibition by wortmannin lead to increased PS exposure. However, only TcdB and C3, but not ROCK- or Akt inhibition led to caspase 3 activation and thus apoptosis. Notably, pancaspase inhibitor zVAD only partially inhibited TcdB-induced PS exposure indicating the existence of apoptotic and non-apoptotic PS exposure. The induced PS exposure coincided with decreased flippase activity as measured with NBD-labeled PS flip-flop. In this study, we show a regulatory role for a novel signaling route, Rho-ROCK-flippase signaling, in maintaining asymmetrical membrane phospholipid distribution in cardiomyocytes.

  4. The Phosphatidylserine and Phosphatidylethanolamine Receptor CD300a Binds Dengue Virus and Enhances Infection

    PubMed Central

    Carnec, Xavier; Meertens, Laurent; Dejarnac, Ophélie; Perera-Lecoin, Manuel; Hafirassou, Mohamed Lamine; Kitaura, Jiro; Ramdasi, Rasika; Schwartz, Olivier

    2015-01-01

    ABSTRACT Dengue virus (DENV) is the etiological agent of the major human arboviral disease. We previously demonstrated that the TIM and TAM families of phosphatidylserine (PtdSer) receptors involved in the phagocytosis of apoptotic cells mediate DENV entry into target cells. We show here that human CD300a, a recently identified phospholipid receptor, also binds directly DENV particles and enhances viral entry. CD300a facilitates infection of the four DENV serotypes, as well as of other mosquito-borne viruses such as West Nile virus and Chikungunya virus. CD300a acts as an attachment factor that enhances DENV internalization through clathrin-mediated endocytosis. CD300a recognizes predominantly phosphatidylethanolamine (PtdEth) and to a lesser extent PtdSer associated with viral particles. Mutation of residues in the IgV domain critical for phospholipid binding abrogate CD300a-mediated enhancement of DENV infection. Finally, we show that CD300a is expressed at the surface of primary macrophages and anti-CD300a polyclonal antibodies partially inhibited DENV infection of these cells. Overall, these data indicate that CD300a is a novel DENV binding receptor that recognizes PtdEth and PtdSer present on virions and enhance infection. IMPORTANCE Dengue disease, caused by dengue virus (DENV), has emerged as the most important mosquito-borne viral disease of humans and is a major global health concern. The molecular bases of DENV-host cell interactions during virus entry are poorly understood, hampering the discovery of new targets for antiviral intervention. We recently discovered that the TIM and TAM proteins, two receptor families involved in the phosphatidylserine (PtdSer)-dependent phagocytic removal of apoptotic cells, interact with DENV particles-associated PtdSer through a mechanism that mimics the recognition of apoptotic cells and mediate DENV infection. In this study, we show that CD300a, a novel identified phospholipid receptor, mediates DENV infection. CD300a

  5. Atomic View of Calcium-Induced Clustering of Phosphatidylserine in Mixed Lipid Bilayers†

    PubMed Central

    Boettcher, John M.; Davis-Harrison, Rebecca L.; Clay, Mary C.; Nieuwkoop, Andrew J.; Ohkubo, Y. Zenmei; Tajkhorshid, Emad; Morrissey, James H.; Rienstra, Chad M.

    2011-01-01

    Membranes play key regulatory roles in biological processes, with bilayer composition exerting marked effects on binding affinities and catalytic activities of a number of membrane-associated proteins. In particular, proteins involved in diverse processes such as vesicle fusion, intracellular signaling cascades, and blood coagulation interact specifically with anionic lipids such as phosphatidylserine (PS) in the presence of Ca2+ ions. While Ca2+ is suspected to induce PS clustering in mixed phospholipid bilayers, the detailed structural effects of this ion on anionic lipids are not established. In this study, combining magic angle spinning (MAS) solid-state NMR (SSNMR) measurements of isotopically labeled serine headgroups in mixed lipid bilayers with molecular dynamics (MD) simulations of PS lipid bilayers in the presence of different counterions, we provide site-resolved insights into the effects of Ca2+ on the structure and dynamics of lipid bilayers. Ca2+-induced conformational changes of PS in mixed bilayers are observed in both liposomes and Nanodiscs, a nanoscale membrane-mimetic of bilayer patches. Site-resolved multidimensional correlation SSNMR spectra of bilayers containing 13C, 15N-labeled PS demonstrate that Ca2+ ions promote two major PS headgroup conformations, which are well resolved in two-dimensional 13C-13C, 15N-13C and 31P-13C spectra. The results of MD simulations performed on PS lipid bilayers in the presence or absence of Ca2+ provide an atomic view of the conformational effects underlying the observed spectra. PMID:21294564

  6. Oral administration of squid lecithin-transphosphatidylated phosphatidylserine improves memory impairment in aged rats.

    PubMed

    Lee, Bombi; Sur, Bong-Jun; Han, Jeong-Jun; Shim, Insop; Her, Song; Lee, Yang-Seok; Lee, Hye-Jung; Hahm, Dae-Hyun

    2015-01-01

    Recently, lecithin-derived phosphatidylserine (PS), which originates from marine life, has received much attention as a viable alternative to bovine cerebral cortex PS. In this study, the use of squid phosphatidylcholine-transphosphatidylated PS (SQ-PS) was evaluated through examination of its ameliorating effects on age-associated learning and memory deficits in rats. Aged rats were orally administered SQ-PS (10, 20, or 50 mg/kg per day) once a day for seven days 30 min prior to behavioral assessment in a Morris water maze. SQ-PS administration produced significant dose-dependent improvements in escape latency for finding the platform in the Morris water maze in the aged rats even though Soy-PS administration also exhibited comparable improvements with SQ-PS. Biochemical alterations in the hippocampal cholinergic system, including changes in choline acetyltransferase and acetylcholinesterase immunoreactivity, were consistent with the behavioral results. In addition, SQ-PS treatment significantly restored age-associated decreases of choline transporter and muscarinic acetylcholine receptor type 1 mRNA expression in the hippocampus. These results demonstrate that orally administered SQ-PS dose-dependently aids in the improvement of memory deficits that occur during normal aging in rats. This suggests that SQ-PS may be a useful therapeutic agent in the treatment of diminished memory function in elderly people.

  7. Calcium transport in vesicles from carrot cells: Stimulation by calmodulin and phosphatidylserine. [Daucus carota cv. Danvers

    SciTech Connect

    Wenling Hsieh; Sze, Heven )

    1991-05-01

    The transport properties of Ca-pumping ATPases from carrot (Daucus carota cv. Danvers) tissue culture cells were studied. ATP dependent Ca transport in vesicles that comigrated with an ER marker, was stimulated 3-4 fold by calmodulin. Cyclopiazonic acid (a specific inhibitor of the sarcoplasmic/endoplasmic reticulum Ca-ATPase) partially inhibited oxalate-stimulated Ca transport activity; however, it had little or not effect on calmodulin-stimulated Ca uptake. The results suggested the presence of two types of Ca ATPases, and ER- and a plasma membrane-type. Incubation of membranes with (gamma{sup 32}P)ATP resulted in the formation of a single acyl ({sup 32}P) phosphoprotein of 120 kDa. Formation of this phosphoprotein was dependent on Ca, and enhanced by La {sup 3+}, characteristic of the plasma membrane CaATPase. Acidic phospholipids, like phosphatidylserine, stimulated Ca transport, similar to their effect on the erythrocyte plasma membrane CaATPase. These results would indicate that the calmodulin-stimulated Ca transport originated in large part from a plasma membrane-type Ca pump of 120 kDa.

  8. T cell Immunoglobulin Mucin Protein (TIM)-4 binds phosphatidylserine and mediates uptake of apoptotic cells

    PubMed Central

    Kobayashi, Norimoto; Karisola, Piia; Peña-Cruz, Victor; Dorfman, David M.; Jinushi, Masahisa; Umetsu, Sarah E.; Butte, Manish J.; Nagumo, Haruo; Chernova, Irene; Zhu, Baogong; Sharpe, Arlene H.; Ito, Susumu; Dranoff, Glenn; Kaplan, Gerardo G.; Casasnovas, Jose M.; Umetsu, Dale T.; DeKruyff, Rosemarie H.; Freeman, Gordon J.

    2009-01-01

    Summary The T cell immunoglobulin mucin (TIM) proteins regulate T cell activation and tolerance. Both TIM-4, expressed on human and mouse macrophages and dendritic cells, and TIM-1 specifically bind to phosphatidylserine (PS) on the surface of apoptotic cells and do not bind to any other phospholipid tested. TIM-4+ peritoneal macrophages, TIM-1+ kidney cells, as well as TIM-4 or TIM-1 transfected cells efficiently phagocytose apoptotic cells and phagocytosis can be blocked by TIM-4 or TIM-1 mAbs. TIM proteins have a unique binding cavity made by an unusual conformation of the CC′ and FG loops of the TIM IgV domain and mutations in this cavity eliminated PS binding and phagocytosis. TIM-4 mAbs that block PS binding and phagocytosis map to epitopes in this binding cavity. These results show that TIM-4 and TIM-1 are immunologically restricted members of the group of receptors that recognize PS, critical for the efficient clearance of apoptotic cells and prevention of autoimmunity. PMID:18082433

  9. The influence of soy-derived phosphatidylserine on cognition in age-associated memory impairment.

    PubMed

    Jorissen, B L; Brouns, F; Van Boxtel, M P; Ponds, R W; Verhey, F R; Jolles, J; Riedel, W J

    2001-01-01

    Phosphatidylserine (PS) is a phospholipid widely sold as a nutritional supplement. PS has been claimed to enhance neuronal membrane function and hence cognitive function, especially in the elderly. We report the results of a clinical trial of soybean-derived PS (S-PS) in aging subjects with memory complaints. Subjects were 120 elderly (> 57 years) of both sexes who fulfilled the more stringent criteria for age-associated memory impairment (AAMI); some also fulfilled the criteria for age-associated cognitive decline. Subjects were allocated at random to one of the three treatment groups: placebo, 300mg S-PS daily, or 600mg S-PS daily. Assessments were carried out at baseline, after 6 and 12 weeks of treatment, and after a wash-out period of 3 weeks. Tests of learning and memory, choice reaction time, planning and attentional functions were administered at each assessment. Delayed recall and recognition of a previously learned word list comprised the primary outcome measures. No significant differences were found in any of the outcome variables between the treatment groups. There were also no significant interactions between treatment and 'severity of memory complaints'. In conclusion, a daily supplement of S-PS does not affect memory or other cognitive functions in older individuals with memory complaints. PMID:11842880

  10. Phosphatidylserine treatment relieves the block to retrovirus infection of cells expressing glycosylated virus receptors

    PubMed Central

    Coil, David A; Miller, A Dusty

    2005-01-01

    Background A major determinant of retrovirus host range is the presence or absence of appropriate cell-surface receptors required for virus entry. Often orthologs of functional receptors are present in a wide range of species, but amino acid differences can render these receptors non-functional. In some cases amino acid differences result in additional N-linked glycosylation that blocks virus infection. The latter block to retrovirus infection can be overcome by treatment of cells with compounds such as tunicamycin, which prevent the addition of N-linked oligosaccharides. Results We have discovered that treatment of cells with liposomes composed of phosphatidylserine (PS) can also overcome the block to infection mediated by N-linked glycosylation. Importantly, this effect occurs without apparent change in the glycosylation state of the receptors for these viruses. This effect occurs with delayed kinetics compared to previous results showing enhancement of virus infection by PS treatment of cells expressing functional virus receptors. Conclusion We have demonstrated that PS treatment can relieve the block to retrovirus infection of cells expressing retroviral receptors that have been rendered non-functional by glycosylation. These findings have important implications for the current model describing inhibition of virus entry by receptor glycosylation. PMID:16091143

  11. Involvement of Sac1 phosphoinositide phosphatase in the metabolism of phosphatidylserine in the yeast Saccharomyces cerevisiae.

    PubMed

    Tani, Motohiro; Kuge, Osamu

    2014-04-01

    Sac1 is a phosphoinositide phosphatase that preferentially dephosphorylates phosphatidylinositol 4-phosphate. Mutation of SAC1 causes not only the accumulation of phosphoinositides but also reduction of the phosphatidylserine (PS) level in the yeast Saccharomyces cerevisiae. In this study, we characterized the mechanism underlying the PS reduction in SAC1-deleted cells. Incorporation of (32) P into PS was significantly delayed in sac1∆ cells. Such a delay was also observed in SAC1- and PS decarboxylase gene-deleted cells, suggesting that the reduction in the PS level is caused by a reduction in the rate of biosynthesis of PS. A reduction in the PS level was also observed with repression of STT4 encoding phosphatidylinositol 4-kinase or deletion of VPS34 encoding phophatidylinositol 3-kinase. However, the combination of mutations of SAC1 and STT4 or VPS34 did not restore the reduced PS level, suggesting that both the synthesis and degradation of phosphoinositides are important for maintenance of the PS level. Finally, we observed an abnormal PS distribution in sac1∆ cells when a specific probe for PS was expressed. Collectively, these results suggested that Sac1 is involved in the maintenance of a normal rate of biosynthesis and distribution of PS.

  12. Structural and Biological Interaction of hsc-70 Protein with Phosphatidylserine in Endosomal Microautophagy.

    PubMed

    Morozova, Kateryna; Clement, Cristina C; Kaushik, Susmita; Stiller, Barbara; Arias, Esperanza; Ahmad, Atta; Rauch, Jennifer N; Chatterjee, Victor; Melis, Chiara; Scharf, Brian; Gestwicki, Jason E; Cuervo, Ana-Maria; Zuiderweg, Erik R P; Santambrogio, Laura

    2016-08-26

    hsc-70 (HSPA8) is a cytosolic molecular chaperone, which plays a central role in cellular proteostasis, including quality control during protein refolding and regulation of protein degradation. hsc-70 is pivotal to the process of macroautophagy, chaperone-mediated autophagy, and endosomal microautophagy. The latter requires hsc-70 interaction with negatively charged phosphatidylserine (PS) at the endosomal limiting membrane. Herein, by combining plasmon resonance, NMR spectroscopy, and amino acid mutagenesis, we mapped the C terminus of the hsc-70 LID domain as the structural interface interacting with endosomal PS, and we estimated an hsc-70/PS equilibrium dissociation constant of 4.7 ± 0.1 μm. This interaction is specific and involves a total of 4-5 lysine residues. Plasmon resonance and NMR results were further experimentally validated by hsc-70 endosomal binding experiments and endosomal microautophagy assays. The discovery of this previously unknown contact surface for hsc-70 in this work elucidates the mechanism of hsc-70 PS/membrane interaction for cytosolic cargo internalization into endosomes. PMID:27405763

  13. INTRACELLULAR TRANSPORT. Phosphatidylserine transport by ORP/Osh proteins is driven by phosphatidylinositol 4-phosphate.

    PubMed

    Moser von Filseck, Joachim; Čopič, Alenka; Delfosse, Vanessa; Vanni, Stefano; Jackson, Catherine L; Bourguet, William; Drin, Guillaume

    2015-07-24

    In eukaryotic cells, phosphatidylserine (PS) is synthesized in the endoplasmic reticulum (ER) but is highly enriched in the plasma membrane (PM), where it contributes negative charge and to specific recruitment of signaling proteins. This distribution relies on transport mechanisms whose nature remains elusive. Here, we found that the PS transporter Osh6p extracted phosphatidylinositol 4-phosphate (PI4P) and exchanged PS for PI4P between two membranes. We solved the crystal structure of Osh6p:PI4P complex and demonstrated that the transport of PS by Osh6p depends on PI4P recognition in vivo. Finally, we showed that the PI4P-phosphatase Sac1p, by maintaining a PI4P gradient at the ER/PM interface, drove PS transport. Thus, PS transport by oxysterol-binding protein-related protein (ORP)/oxysterol-binding homology (Osh) proteins is fueled by PI4P metabolism through PS/PI4P exchange cycles.

  14. Phosphatidylserine is a global immunosuppressive signal in efferocytosis, infectious disease, and cancer

    PubMed Central

    Birge, R B; Boeltz, S; Kumar, S; Carlson, J; Wanderley, J; Calianese, D; Barcinski, M; Brekken, R A; Huang, X; Hutchins, J T; Freimark, B; Empig, C; Mercer, J; Schroit, A J; Schett, G; Herrmann, M

    2016-01-01

    Apoptosis is an evolutionarily conserved and tightly regulated cell death modality. It serves important roles in physiology by sculpting complex tissues during embryogenesis and by removing effete cells that have reached advanced age or whose genomes have been irreparably damaged. Apoptosis culminates in the rapid and decisive removal of cell corpses by efferocytosis, a term used to distinguish the engulfment of apoptotic cells from other phagocytic processes. Over the past decades, the molecular and cell biological events associated with efferocytosis have been rigorously studied, and many eat-me signals and receptors have been identified. The externalization of phosphatidylserine (PS) is arguably the most emblematic eat-me signal that is in turn bound by a large number of serum proteins and opsonins that facilitate efferocytosis. Under physiological conditions, externalized PS functions as a dominant and evolutionarily conserved immunosuppressive signal that promotes tolerance and prevents local and systemic immune activation. Pathologically, the innate immunosuppressive effect of externalized PS has been hijacked by numerous viruses, microorganisms, and parasites to facilitate infection, and in many cases, establish infection latency. PS is also profoundly dysregulated in the tumor microenvironment and antagonizes the development of tumor immunity. In this review, we discuss the biology of PS with respect to its role as a global immunosuppressive signal and how PS is exploited to drive diverse pathological processes such as infection and cancer. Finally, we outline the rationale that agents targeting PS could have significant value in cancer and infectious disease therapeutics. PMID:26915293

  15. Antibodies to Phosphatidylserine/Prothrombin Complex in Antiphospholipid Syndrome: Analytical and Clinical Perspectives.

    PubMed

    Peterson, Lisa K; Willis, Rohan; Harris, E Nigel; Branch, Ware D; Tebo, Anne E

    2016-01-01

    Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis and/or pregnancy-related morbidity accompanied by persistently positive antiphospholipid antibodies (aPL). Current laboratory criteria for APS classification recommend testing for lupus anticoagulant as well as IgG and IgM anticardiolipin, and beta-2 glycoprotein I (anti-β2GPI) antibodies. However, there appears to be a subset of patients with classical APS manifestations who test negative for the recommended criteria aPL tests. While acknowledging that such patients may have clinical features that are not of an autoimmune etiology, experts also speculate that these "seronegative" patients may test negative for relevant autoantibodies as a result of a lack of harmonization and/or standardization. Alternatively, they may have aPL that target other antigens involved in the pathogenesis of APS. In the latter, autoantibodies that recognize a phosphatidylserine/prothrombin (PS/PT) complex have been reported to be associated with APS and may have diagnostic relevance. This review highlights analytical and clinical attributes associated with PS/PT antibodies, taking into consideration the performance characteristics of criteria aPL tests in APS with specific recommendations for harmonization and standardization efforts.

  16. SUI-family genes encode phosphatidylserine synthases and regulate stem development in rice.

    PubMed

    Yin, Hengfu; Gao, Peng; Liu, Chengwu; Yang, Jun; Liu, Zhongchi; Luo, Da

    2013-01-01

    In vascular plants, the regulation of stem cell niche determines development of aerial shoot which consists of stems and lateral organs. Intercalary meristem (IM) controls internode elongation in rice and other grasses, however little attention has been paid to the underlying mechanism of stem cell maintenance. Here, we investigated the stem development in rice and showed that the Shortened Uppermost Internode 1 (SUI1) family of genes are pivotal for development of rice stems. We demonstrated that SUI-family genes regulate the development of IM for internode elongation and also the cell expansion of the panicle stem rachis in rice. The SUI-family genes encoded base-exchange types of phosphatidylserine synthases (PSSs), which possessed enzymatic activity in a yeast complementary assay. Overexpression of SUI1 and SUI2 caused outgrowths of internodes during vegetative development, and we showed that expression patterns of Oryza Sativa Homeobox 15 (OSH15) and Histone4 were impaired. Furthermore, genome-wide gene expression analysis revealed that overexpression and RNA knockdown of SUI-family genes affected downstream gene expression related to phospholipid metabolic pathways. Moreover, using Ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry, we analyzed PS contents in different genetic backgrounds of rice and showed that the quantity of very long chain fatty acids PS is affected by transgene of SUI-family genes. Our study reveals a new mechanism conveyed by the SUI1 pathway and provides evidence to link lipid metabolism with plant stem cell maintenance.

  17. Transport through recycling endosomes requires EHD1 recruitment by a phosphatidylserine translocase

    PubMed Central

    Lee, Shoken; Uchida, Yasunori; Wang, Jiao; Matsudaira, Tatsuyuki; Nakagawa, Takatoshi; Kishimoto, Takuma; Mukai, Kojiro; Inaba, Takehiko; Kobayashi, Toshihide; Molday, Robert S; Taguchi, Tomohiko; Arai, Hiroyuki

    2015-01-01

    P4-ATPases translocate aminophospholipids, such as phosphatidylserine (PS), to the cytosolic leaflet of membranes. PS is highly enriched in recycling endosomes (REs) and is essential for endosomal membrane traffic. Here, we show that PS flipping by an RE-localized P4-ATPase is required for the recruitment of the membrane fission protein EHD1. Depletion of ATP8A1 impaired the asymmetric transbilayer distribution of PS in REs, dissociated EHD1 from REs, and generated aberrant endosomal tubules that appear resistant to fission. EHD1 did not show membrane localization in cells defective in PS synthesis. ATP8A2, a tissue-specific ATP8A1 paralogue, is associated with a neurodegenerative disease (CAMRQ). ATP8A2, but not the disease-causative ATP8A2 mutant, rescued the endosomal defects in ATP8A1-depleted cells. Primary neurons from Atp8a2−/− mice showed a reduced level of transferrin receptors at the cell surface compared to Atp8a2+/+ mice. These findings demonstrate the role of P4-ATPase in membrane fission and give insight into the molecular basis of CAMRQ. PMID:25595798

  18. Phosphatidylserine translocation at the yeast trans-Golgi network regulates protein sorting into exocytic vesicles

    PubMed Central

    Hankins, Hannah M.; Sere, Yves Y.; Diab, Nicholas S.; Menon, Anant K.; Graham, Todd R.

    2015-01-01

    Sorting of plasma membrane proteins into exocytic vesicles at the yeast trans-Golgi network (TGN) is believed to be mediated by their coalescence with specific lipids, but how these membrane-remodeling events are regulated is poorly understood. Here we show that the ATP-dependent phospholipid flippase Drs2 is required for efficient segregation of cargo into exocytic vesicles. The plasma membrane proteins Pma1 and Can1 are missorted from the TGN to the vacuole in drs2∆ cells. We also used a combination of flippase mutants that either gain or lose the ability to flip phosphatidylserine (PS) to determine that PS flip by Drs2 is its critical function in this sorting event. The primary role of PS flip at the TGN appears to be to control the oxysterol-binding protein homologue Kes1/Osh4 and regulate ergosterol subcellular distribution. Deletion of KES1 suppresses plasma membrane–missorting defects and the accumulation of intracellular ergosterol in drs2 mutants. We propose that PS flip is part of a homeostatic mechanism that controls sterol loading and lateral segregation of protein and lipid domains at the TGN. PMID:26466678

  19. Phosphatidylserine flipping enhances membrane curvature and negative charge required for vesicular transport

    PubMed Central

    Xu, Peng; Baldridge, Ryan D.; Chi, Richard J.; Burd, Christopher G.

    2013-01-01

    Vesicle-mediated protein transport between organelles of the secretory and endocytic pathways is strongly influenced by the composition and organization of membrane lipids. In budding yeast, protein transport between the trans-Golgi network (TGN) and early endosome (EE) requires Drs2, a phospholipid translocase in the type IV P-type ATPase family. However, downstream effectors of Drs2 and specific phospholipid substrate requirements for protein transport in this pathway are unknown. Here, we show that the Arf GTPase-activating protein (ArfGAP) Gcs1 is a Drs2 effector that requires a variant of the ArfGAP lipid packing sensor (+ALPS) motif for localization to TGN/EE membranes. Drs2 increases membrane curvature and anionic phospholipid composition of the cytosolic leaflet, both of which are sensed by the +ALPS motif. Using mutant forms of Drs2 and the related protein Dnf1, which alter their ability to recognize phosphatidylserine, we show that translocation of this substrate to the cytosolic leaflet is essential for +ALPS binding and vesicular transport between the EE and the TGN. PMID:24019533

  20. TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity

    PubMed Central

    Freeman, Gordon J.; Casasnovas, Jose M.; Umetsu, Dale T.; DeKruyff, Rosemarie H.

    2010-01-01

    Summary The TIM (T cell/transmembrane, immunoglobulin, and mucin) gene family plays a critical role in regulating immune responses, including allergy, asthma, transplant tolerance, autoimmunity, and the response to viral infections. The unique structure of TIM immunoglobulin variable region domains allows highly specific recognition of phosphatidylserine (PtdSer), exposed on the surface of apoptotic cells. TIM-1, TIM-3, and TIM-4 all recognize PtdSer but differ in expression, suggesting that they have distinct functions in regulating immune responses. TIM-1, an important susceptibility gene for asthma and allergy, is preferentially expressed on T-helper 2 (Th2) cells and functions as a potent costimulatory molecule for T-cell activation. TIM-3 is preferentially expressed on Th1 and Tc1 cells, and generates an inhibitory signal resulting in apoptosis of Th1 and Tc1 cells. TIM-3 is also expressed on some dendritic cells and can mediate phagocytosis of apoptotic cells and cross-presentation of antigen. In contrast, TIM-4 is exclusively expressed on antigen-presenting cells, where it mediates phagocytosis of apoptotic cells and plays an important role in maintaining tolerance. TIM molecules thus provide a functional repertoire for recognition of apoptotic cells, which determines whether apoptotic cell recognition leads to immune activation or tolerance, depending on the TIM molecule engaged and the cell type on which it is expressed. PMID:20536563

  1. Phosphatidylserine Targets Single-Walled Carbon Nanotubes to Professional Phagocytes In Vitro and In Vivo

    PubMed Central

    Konduru, Nagarjun V.; Tyurina, Yulia Y.; Feng, Weihong; Basova, Liana V.; Belikova, Natalia A.; Bayir, Hülya; Clark, Katherine; Rubin, Marc; Stolz, Donna; Vallhov, Helen; Scheynius, Annika; Witasp, Erika; Fadeel, Bengt; Kichambare, Padmakar D.; Star, Alexander; Kisin, Elena R.; Murray, Ashley R.; Shvedova, Anna A.; Kagan, Valerian E.

    2009-01-01

    Broad applications of single-walled carbon nanotubes (SWCNT) dictate the necessity to better understand their health effects. Poor recognition of non-functionalized SWCNT by phagocytes is prohibitive towards controlling their biological action. We report that SWCNT coating with a phospholipid “eat-me” signal, phosphatidylserine (PS), makes them recognizable in vitro by different phagocytic cells - murine RAW264.7 macrophages, primary monocyte-derived human macrophages, dendritic cells, and rat brain microglia. Macrophage uptake of PS-coated nanotubes was suppressed by the PS-binding protein, Annexin V, and endocytosis inhibitors, and changed the pattern of pro- and anti-inflammatory cytokine secretion. Loading of PS-coated SWCNT with pro-apoptotic cargo (cytochrome c) allowed for the targeted killing of RAW264.7 macrophages. In vivo aspiration of PS-coated SWCNT stimulated their uptake by lung alveolar macrophages in mice. Thus, PS-coating can be utilized for targeted delivery of SWCNT with specified cargoes into professional phagocytes, hence for therapeutic regulation of specific populations of immune-competent cells. PMID:19198650

  2. Interactions of c-Raf-1 with phosphatidylserine and 14-3-3.

    PubMed

    McPherson, R A; Harding, A; Roy, S; Lane, A; Hancock, J F

    1999-07-01

    Activation of Raf-1 occurs at the plasma membrane. We recently showed that 14-3-3 must be complexed with Raf-1 for efficient recruitment to the plasma membrane and activation by Ras, but that 14-3-3 is completely displaced from Raf-1 following plasma membrane binding. We show here that the Raf-1 zinc finger is not absolutely required for 14-3-3 binding but is required to stabilize the interaction between Raf-1 and 14-3-3. Incubation of Raf-1 with phosphatidylserine, an inner plasma membrane phospholipid, results in removal of 14-3-3 and an increase in Raf-1 kinase activity, whereas removal of 14-3-3 from Raf-1 using specific phosphopeptides substantially reduces Raf-1 basal kinase activity. Displacement of 14-3-3 from activated Raf-1 by phosphopeptides has no effect on kinase activity if Raf-1 is first removed from solution, but completely eradicates kinase activity of soluble activated Raf-1. These results suggest a mechanism for the removal of 14-3-3 from Raf-1 at the plasma membrane and show that removal of 14-3-3 from Raf-1 has markedly different effects depending on experimental conditions.

  3. Platelet binding sites for factor VIII in relation to fibrin and phosphatidylserine.

    PubMed

    Gilbert, Gary E; Novakovic, Valerie A; Shi, Jialan; Rasmussen, Jan; Pipe, Steven W

    2015-09-01

    Thrombin-stimulated platelets expose very little phosphatidylserine (PS) but express binding sites for factor VIII (fVIII), casting doubt on the role of exposed PS as the determinant of binding sites. We previously reported that fVIII binding sites are increased three- to sixfold when soluble fibrin (SF) binds the αIIbβ3 integrin. This study focuses on the hypothesis that platelet-bound SF is the major source of fVIII binding sites. Less than 10% of fVIII was displaced from thrombin-stimulated platelets by lactadherin, a PS-binding protein, and an fVIII mutant defective in PS-dependent binding retained platelet affinity. Therefore, PS is not the determinant of most binding sites. FVIII bound immobilized SF and paralleled platelet binding in affinity, dependence on separation from von Willebrand factor, and mediation by the C2 domain. SF also enhanced activity of fVIII in the factor Xase complex by two- to fourfold. Monoclonal antibody (mAb) ESH8, against the fVIII C2 domain, inhibited binding of fVIII to SF and platelets but not to PS-containing vesicles. Similarly, mAb ESH4 against the C2 domain, inhibited >90% of platelet-dependent fVIII activity vs 35% of vesicle-supported activity. These results imply that platelet-bound SF is a component of functional fVIII binding sites. PMID:26162408

  4. Phosphatidylserine increases IKBKAP levels in a humanized knock-in IKBKAP mouse model.

    PubMed

    Bochner, Ron; Ziv, Yael; Zeevi, David; Donyo, Maya; Abraham, Lital; Ashery-Padan, Ruth; Ast, Gil

    2013-07-15

    Familial dysautonomia (FD) is a severe neurodegenerative genetic disorder restricted to the Ashkenazi Jewish population. The most common mutation in FD patients is a T-to-C transition at position 6 of intron 20 of the IKBKAP gene. This mutation causes aberrant skipping of exon 20 in a tissue-specific manner, leading to reduction of the IκB kinase complex-associated protein (IKAP) protein in the nervous system. We established a homozygous humanized mouse strain carrying human exon 20 and its two flanking introns; the 3' intron has the transition observed in the IKBKAP gene of FD patients. Although our FD humanized mouse does not display FD symptoms, the unique, tissue-specific splicing pattern of the IKBKAP in these mice allowed us to evaluate the effect of therapies on gene expression and exon 20 splicing. The FD mice were supplemented with phosphatidylserine (PS), a safe food supplement that increases mRNA and protein levels of IKBKAP in cell lines generated from FD patients. Here we demonstrated that PS treatment increases IKBAKP mRNA and IKAP protein levels in various tissues of FD mice without affecting exon 20 inclusion levels. We also observed that genes associated with transcription regulation and developmental processes were up-regulated in the cerebrum of PS-treated mice. Thus, PS holds promise for the treatment of FD.

  5. Autophagic vesicles on mature human reticulocytes explain phosphatidylserine-positive red cells in sickle cell disease.

    PubMed

    Mankelow, Tosti J; Griffiths, Rebecca E; Trompeter, Sara; Flatt, Joanna F; Cogan, Nicola M; Massey, Edwin J; Anstee, David J

    2015-10-01

    During maturation to an erythrocyte, a reticulocyte must eliminate any residual organelles and reduce its surface area and volume. Here we show this involves a novel process whereby large, intact, inside-out phosphatidylserine (PS)-exposed autophagic vesicles are extruded. Cell surface PS is a well-characterized apoptotic signal initiating phagocytosis. In peripheral blood from patients after splenectomy or in patients with sickle cell disease (SCD), the number of circulating red cells exposing PS on their surface is elevated. We show that in these patients PS is present on the cell surface of red cells in large (∼1.4 µm) discrete areas corresponding to autophagic vesicles. The autophagic vesicles found on reticulocytes are identical to those observed on red cells from splenectomized individuals and patients with SCD. Our data suggest the increased thrombotic risk associated with splenectomy, and patients with hemoglobinopathies is a possible consequence of increased levels of circulating mature reticulocytes expressing inside-out PS-exposed autophagic vesicles because of asplenia.

  6. Phase separation of cholesterol and the interaction of ethanol with phosphatidylserine-cholesterol bilayer membranes.

    PubMed

    Bach, D; Borochov, N; Wachtel, E

    2002-02-01

    Thermotropic and structural effects of ethanol on phosphatidylserine (PS) membranes containing up to 0.4 mol fraction cholesterol were investigated by differential scanning calorimetry, X-ray diffraction and fluorescence spectroscopy. It was found that in the presence of cholesterol, 10% (v/v) added ethanol depresses the melting temperature of the phospholipid by approximately 2 degrees C, similar to what was observed in the absence of cholesterol. Below the melting temperature the progressive disordering effect of added cholesterol is weakly enhanced by the presence of ethanol. In the liquid crystalline state, the marked decrease in the thickness of the bilayer which ethanol causes in the absence of cholesterol (Chem. Phys. Lipids 92 (1998) 127), is also observed in its presence. We conclude that, in contrast to what has been observed for zwitterionic phospholipids, high concentrations of cholesterol do not diminish the interaction of ethanol with PS membranes. With addition of 10% (v/v) ethanol, crystalline cholesterol diffraction, an indication of phase separation of the sterol, appears at mol fraction cholesterol 0.34, as compared to 0.3 in the absence of ethanol (Chem. Phys. Lipids 92 (1998) 71).

  7. Long-Time Cooling before Cryopreservation Decreased Translocation of Phosphatidylserine (Ptd-L-Ser) in Human Ovarian Tissue

    PubMed Central

    2015-01-01

    Objectives To translocation (externalization) of phosphatidylserine lead at least the five negative effects observed during cells cryopreservation: hypoxia, increasing of intracellular Ca2+, osmotic disruption of cellular membranes, generation of reactive oxygen species (ROS) and lipid peroxidation. The aim of this study was to test the intensiveness of the phosphatidylserine translocation immediately after thawing and after 45 d xenografting of human ovarian tissue, which was either frozen just after operative removal from patient or cooled before cryopreservation to 5°C for 24 h and then frozen. Materials and Methods Ovarian fragments from twelve patients were divided into small pieces in form of cortex with medulla, and randomly divided into the following four groups. Pieces of Group 1 (n=30) were frozen immediately after operation, thawed and just after thawing their quality was analyzed. Group 2 pieces (n=30) after operation were cooled to 5°C for 24 h, then frozen after 24 h pre-cooling to 5°C, thawed and just after thawing their quality was analyzed. Group 3 pieces (n=30) were frozen immediately after operation without pre-cooling, thawed, transplanted to SCID mice and then, after 45 d of culture their quality was analyzed. Group 4 pieces (n=30) were frozen after 24 h pre-cooling to 5°C, thawed, transplanted to SCID mice and then, after 45 d their quality was analyzed. The effectiveness of the pre-freezing cooling of tissuewas evaluated by the development of follicles (histology) and by intensiveness of translocation of phosphatidylserine (FACS with FITC-Annexin V and Propidium Iodide). Results For groups 1, 2, 3 and 4 the mean densities of follicles per 1 mm3 was 19.0, 20.2, 12.9, and 12.2, respectively (P1-2, 3-4 >0.1). For these groups, 99%, 98%, 88% and 90% preantral follicles, respectively were morphologically normal (P1-2, 3-4 >0.1). The FACS analysis showed significantly decreased intensiveness of translocation of phosphatidylserine after pre

  8. Phosphatidylserine and Phosphatidylethanolamine Bind to Protein Z Cooperatively and with Equal Affinity.

    PubMed

    Sengupta, Tanusree; Manoj, Narayanan

    2016-01-01

    Protein Z (PZ) is an anticoagulant that binds with high affinity to Protein Z-dependent protease inhibitor (ZPI) and accelerates the rate of ZPI-mediated inhibition of factor Xa (fXa) by more than 1000-fold in the presence of Ca2+ and phospholipids. PZ promotion of the ZPI-fXa interaction results from the anchoring of the Gla domain of PZ onto phospholipid surfaces and positioning the bound ZPI in close proximity to the Gla-anchored fXa, forming a ternary complex of PZ/ZPI/fXa. Although interaction of PZ with phospholipid membrane appears to be absolutely crucial for its cofactor activity, little is known about the binding of different phospholipids to PZ. The present study was conceived to understand the interaction of different phospholipids with PZ. Experiments with both soluble lipids and model membranes revealed that PZ binds to phosphatidylserine (PS) and phosphatidylethanolamine (PE) with equal affinity (Kd~48 μM); further, PS and PE bound to PZ synergistically. Equilibrium dialysis experiments revealed two lipid-binding sites for both PS and PE. PZ binds with weaker affinity to other phospholipids, e.g., phosphatidic acid, phosphatidylglycerol, phosphatidylcholine and binding of these lipids is not synergistic with respect to PS. Both PS and PE -containing membranes supported the formation of a fXa-PZ complex. PZ protection of fXa from antithrombin inhibition were also shown to be comparable in presence of both PS: PC and PE: PC membranes. These findings are particularly important and intriguing since they suggest a special affinity of PZ, in vivo, towards activated platelets, the primary membrane involved in blood coagulation process. PMID:27584039

  9. Effect of calcium and magnesium on phosphatidylserine membranes: experiments and all-atomic simulations.

    PubMed

    Martín-Molina, Alberto; Rodríguez-Beas, César; Faraudo, Jordi

    2012-05-01

    It is known that phosphatidylserine (PS(-)) lipids have a very similar affinity for Ca(2+) and Mg(2+) cations, as revealed by electrokinetic and stability experiments. However, despite this similar affinity, experimental evidence shows that the presence of Ca(2+) or Mg(2+) induces very different aggregation behavior for PS(-) liposomes as characterized by their fractal dimensions. Also, turbidity measurements confirm substantial differences in aggregation behavior depending on the presence of Ca(2+) or Mg(2+) cations. These puzzling results suggest that although these two cations have a similar affinity for PS(-) lipids, they induce substantial structural differences in lipid bilayers containing each of these cations. In other words, these cations have strong ion-specific effects on the structure of PS(-) membranes. This interpretation is supported by all-atomic molecular-dynamics simulations showing that Ca(2+) and Mg(2+) cations have different binding sites and induce different membrane hydration. We show that although both ions are incorporated deep into the hydrophilic region of the membrane, they have different positions and configurations at the membrane. Absorbed Ca(2+) cations present a peak at a distance ~2 nm from the center of the lipid bilayer, and their most probable binding configuration involves two oxygen atoms from each of the charged moieties of the PS molecule (phosphate and carboxyl groups). In contrast, the distribution of absorbed Mg(2+) cations has two different peaks, located a few angstroms before and after the Ca(2+) peak. The most probable configurations (corresponding to these two peaks) involve binding to two oxygen atoms from carboxyl groups (the most superficial binding peak) or two oxygen atoms from phosphate groups (the most internal peak). Moreover, simulations also show differences in the hydration structure of the membrane: we obtained a hydration of 7.5 and 9 water molecules per lipid in simulations with Ca(2+) and Mg(2

  10. A simple flow cytometry method improves the detection of phosphatidylserine-exposing extracellular vesicles

    PubMed Central

    Arraud, N; Gounou, C; Linares, R; Brisson, A R

    2015-01-01

    Background Plasma contains cell-derived extracellular vesicles (EVs), which participate in physiopathological processes and have potential applications as disease biomarker. However, the enumeration of EVs faces major problems, due to their sub-micrometer size and to intrinsic limitations in methods of characterization, mainly flow cytometry (FCM). Objectives Our objective is to enumerate EVs in plasma, by taking as the prototype the population of phosphatidylserine (PS)-exposing EVs, which constitute one of the major EV populations and are responsible for thrombotic disorders. Methods The concentration of PS-exposing EVs in platelet-free plasma (PFP) of healthy subjects was measured by FCM using either light scattering or fluorescence as the trigger and fluorescent Annexin-5 (Anx5) as the specific label. In addition, PS-exposing EVs were enumerated by electron microscopy (EM) after labeling with Anx5 gold nanoparticles and sedimentation on EM grids. Results We show that about 50× more Anx5-positive EVs are detected by FCM when detection is triggered on fluorescence as compared with light scattering. By fluorescence triggering, concentrations of 22 000–30 000 Anx5-positive EVs per μL PFP were determined, using two different flow cytometers. The limit of detection of the fluorescence triggering method was estimated at about 1000–2500 Anx5 molecules. Results from EM suggest that EVs down to 100–150 nm diameter are detected by fluorescence triggering. Conclusion This study presents a simple method for enumerating EVs. We believe that this method is applicable in a general context and will improve our understanding of the roles of EVs in pathophysiological situations, which will open avenues for the development of EV-based diagnosis assays. PMID:25348269

  11. The phosphatidylserine receptor TIM4 utilizes integrins as coreceptors to effect phagocytosis.

    PubMed

    Flannagan, Ronald S; Canton, Johnathan; Furuya, Wendy; Glogauer, Michael; Grinstein, Sergio

    2014-05-01

    T-cell immunoglobulin mucin protein 4 (TIM4), a phosphatidylserine (PtdSer)-binding receptor, mediates the phagocytosis of apoptotic cells. How TIM4 exerts its function is unclear, and conflicting data have emerged. To define the mode of action of TIM4, we used two distinct but complementary approaches: 1) we compared bone marrow-derived macrophages from wild-type and TIM4(-/-) mice, and 2) we heterologously expressed TIM4 in epithelioid AD293 cells, which rendered them competent for engulfment of PtdSer-bearing targets. Using these systems, we demonstrate that rather than serving merely as a tether, as proposed earlier by others, TIM4 is an active participant in the phagocytic process. Furthermore, we find that TIM4 operates independently of lactadherin, which had been proposed to act as a bridging molecule. Of interest, TIM4-driven phagocytosis depends on the activation of integrins and involves stimulation of Src-family kinases and focal adhesion kinase, as well as the localized accumulation of phosphatidylinositol 3,4,5-trisphosphate. These mediators promote recruitment of the nucleotide-exchange factor Vav3, which in turn activates small Rho-family GTPases. Gene silencing or ablation experiments demonstrated that RhoA, Rac1, and Rac2 act synergistically to drive the remodeling of actin that underlies phagocytosis. Single-particle detection experiments demonstrated that TIM4 and β1 integrins associate upon receptor clustering. These findings support a model in which TIM4 engages integrins as coreceptors to evoke the signal transduction needed to internalize PtdSer-bearing targets such as apoptotic cells.

  12. Inhibition of Acid Sphingomyelinase Depletes Cellular Phosphatidylserine and Mislocalizes K-Ras from the Plasma Membrane.

    PubMed

    Cho, Kwang-Jin; van der Hoeven, Dharini; Zhou, Yong; Maekawa, Masashi; Ma, Xiaoping; Chen, Wei; Fairn, Gregory D; Hancock, John F

    2015-01-01

    K-Ras must localize to the plasma membrane for biological activity; thus, preventing plasma membrane interaction blocks K-Ras signal output. Here we show that inhibition of acid sphingomyelinase (ASM) mislocalizes both the K-Ras isoforms K-Ras4A and K-Ras4B from the plasma membrane to the endomembrane and inhibits their nanoclustering. We found that fendiline, a potent ASM inhibitor, reduces the phosphatidylserine (PtdSer) and cholesterol content of the inner plasma membrane. These lipid changes are causative because supplementation of fendiline-treated cells with exogenous PtdSer rapidly restores K-Ras4A and K-Ras4B plasma membrane binding, nanoclustering, and signal output. Conversely, supplementation with exogenous cholesterol restores K-Ras4A but not K-Ras4B nanoclustering. These experiments reveal different operational pools of PtdSer on the plasma membrane. Inhibition of ASM elevates cellular sphingomyelin and reduces cellular ceramide levels. Concordantly, delivery of recombinant ASM or exogenous ceramide to fendiline-treated cells rapidly relocalizes K-Ras4B and PtdSer to the plasma membrane. K-Ras4B mislocalization is also recapitulated in ASM-deficient Neimann-Pick type A and B fibroblasts. This study identifies sphingomyelin metabolism as an indirect regulator of K-Ras4A and K-Ras4B signaling through the control of PtdSer plasma membrane content. It also demonstrates the critical and selective importance of PtdSer to K-Ras4A and K-Ras4B plasma membrane binding and nanoscale spatial organization. PMID:26572827

  13. Phosphatidylserine-Dependent Catalysis of Stalk and Pore Formation by Synaptobrevin JMR-TMD Peptide.

    PubMed

    Tarafdar, Pradip K; Chakraborty, Hirak; Bruno, Michael J; Lentz, Barry R

    2015-11-01

    Although the importance of a SNARE complex in neurotransmitter release is widely accepted, there exist different views on how the complex promotes fusion. One hypothesis is that the SNARE complex's ability to bring membranes into contact is sufficient for fusion, another points to possible roles of juxtamembrane regions (JMRs) and transmembrane domains (TMDs) in catalyzing lipid rearrangement, and another notes the complex's presumed ability to bend membranes near the point of contact. Here, we performed experiments with highly curved vesicles brought into contact using low concentrations of polyethylene glycol (PEG) to investigate the influence of the synaptobrevin (SB) TMD with an attached JMR (SB-JMR-TMD) on the rates of stalk and pore formation during vesicle fusion. SB-JMR-TMD enhanced the rates of stalk and fusion pore (FP) formation in a sharply sigmoidal fashion. We observed an optimal influence at an average of three peptides per vesicle, but only with phosphatidylserine (PS)-containing vesicles. Approximately three SB-JMR-TMDs per vesicle optimally ordered the bilayer interior and excluded water in a similar sigmoidal fashion. The catalytic influences of hexadecane and SB-JMR-TMD on fusion kinetics showed little in common, suggesting different mechanisms. Both kinetic and membrane structure measurements support the hypotheses that SB-JMR-TMD 1) catalyzes initial intermediate formation as a result of its basic JMR disrupting ordered interbilayer water and permitting closer interbilayer approach, and 2) catalyzes pore formation by forming a membrane-spanning complex that increases curvature stress at the circumference of the hemifused diaphragm of the prepore intermediate state.

  14. Phosphatidylserine translocation to the mitochondrion is an ATP-dependent process in permeabilized animal cells

    SciTech Connect

    Voelker, D.R. )

    1989-12-01

    Chinese hamster ovary (CHO-K1) cells were pulse labeled with ({sup 3}H)serine, and the synthesis of phosphatidyl({sup 3}H)ethanolamine from phosphatidyl({sup 3}H)serine during the subsequent chase was used as a measure of lipid translocation to the mitochondria. When the CHO-K1 cells were pulse labeled and subsequently permeabilized with 50 {mu}g of saponin per ml, there was no significant turnover of nascent phosphatidyl({sup 3}H)serine to form phosphatidyl({sup 3}H)ethanolamine during an ensuring chase. Supplementation of the permeabilized cells with 2 mM ATP resulted in significant phosphatidyl({sup 3}H)ethanolamine synthesis (83% of that found in intact cells) from phosphatidyl({sup 3}H)serine during a subsequent 2-hr chase. Phosphatidyl({sup 3}H)ethanolamine synthesis essentially ceased after 2 hr in the permeabilized cells. The translocation-dependent synthesis of phosphatidyl({sup 3}H)ethanolamine was a saturable process with respect to ATP concentration in permeabilized cells. The conversion of phosphatidyl({sup 3}H)serine to phosphatidyl({sup 3}H)ethanolamine did not occur in saponin-treated cultures supplemented with 2 mM AMP, 2 mM 5{prime}-adenylyl imidodiphosphate, or apyrase plus 2 mM ATP. ATP was the most effective nucleotide, but the addition of GTP, CTP, UTP, and ADP also supported the translocation-dependent synthesis of phosphatidyl({sup 3}H)ethanolamine albeit to a lesser extent. These data provide evidence that the interorganelle translocation of phosphatidylserine requires ATP and is largely independent of soluble cytosolic proteins.

  15. Computing membrane-AQP5-phosphatidylserine binding affinities with hybrid steered molecular dynamics approach

    PubMed Central

    Chen, Liao Y

    2015-01-01

    In order to elucidate how phosphatidylserine (PS6) interacts with AQP5 in a cell membrane, we develop a hybrid steered molecular dynamics (hSMD) method that involves (1) simultaneously steering two centers of mass of two selected segments of the ligand and (2) equilibrating the ligand-protein complex with and without biasing the system. Validating hSMD, we first study vascular endothelial growth factor receptor 1 (VEGFR1) in complex with N-(4-Chlorophenyl)-2-((pyridin-4-ylmethyl)amino)benzamide (8ST), for which the binding energy is known from in vitro experiments. In this study, our computed binding energy well agrees with the experimental value. Knowing the accuracy of this hSMD method, we apply it to the AQP5-lipid-bilayer system to answer an outstanding question relevant to AQP5’s physiological function: Will the PS6, a lipid having a single long hydrocarbon tail that was found in the central pore of the AQP5 tetramer crystal, actually bind to and inhibit AQP5’s central pore under near-physiological conditions, namely, when AQP5 tetramer is embedded in a lipid bilayer? We find, in silico, using the CHARMM 36 force field, that binding PS6 to AQP5 is a factor of 3 million weaker than “binding” it in the lipid bilayer. This suggests that AQP5’s central pore will not be inhibited by PS6 or a similar lipid in a physiological environment. PMID:25955791

  16. Phosphatidylserine-Dependent Catalysis of Stalk and Pore Formation by Synaptobrevin JMR-TMD Peptide.

    PubMed

    Tarafdar, Pradip K; Chakraborty, Hirak; Bruno, Michael J; Lentz, Barry R

    2015-11-01

    Although the importance of a SNARE complex in neurotransmitter release is widely accepted, there exist different views on how the complex promotes fusion. One hypothesis is that the SNARE complex's ability to bring membranes into contact is sufficient for fusion, another points to possible roles of juxtamembrane regions (JMRs) and transmembrane domains (TMDs) in catalyzing lipid rearrangement, and another notes the complex's presumed ability to bend membranes near the point of contact. Here, we performed experiments with highly curved vesicles brought into contact using low concentrations of polyethylene glycol (PEG) to investigate the influence of the synaptobrevin (SB) TMD with an attached JMR (SB-JMR-TMD) on the rates of stalk and pore formation during vesicle fusion. SB-JMR-TMD enhanced the rates of stalk and fusion pore (FP) formation in a sharply sigmoidal fashion. We observed an optimal influence at an average of three peptides per vesicle, but only with phosphatidylserine (PS)-containing vesicles. Approximately three SB-JMR-TMDs per vesicle optimally ordered the bilayer interior and excluded water in a similar sigmoidal fashion. The catalytic influences of hexadecane and SB-JMR-TMD on fusion kinetics showed little in common, suggesting different mechanisms. Both kinetic and membrane structure measurements support the hypotheses that SB-JMR-TMD 1) catalyzes initial intermediate formation as a result of its basic JMR disrupting ordered interbilayer water and permitting closer interbilayer approach, and 2) catalyzes pore formation by forming a membrane-spanning complex that increases curvature stress at the circumference of the hemifused diaphragm of the prepore intermediate state. PMID:26536263

  17. Effect of calcium and magnesium on phosphatidylserine membranes: experiments and all-atomic simulations.

    PubMed

    Martín-Molina, Alberto; Rodríguez-Beas, César; Faraudo, Jordi

    2012-05-01

    It is known that phosphatidylserine (PS(-)) lipids have a very similar affinity for Ca(2+) and Mg(2+) cations, as revealed by electrokinetic and stability experiments. However, despite this similar affinity, experimental evidence shows that the presence of Ca(2+) or Mg(2+) induces very different aggregation behavior for PS(-) liposomes as characterized by their fractal dimensions. Also, turbidity measurements confirm substantial differences in aggregation behavior depending on the presence of Ca(2+) or Mg(2+) cations. These puzzling results suggest that although these two cations have a similar affinity for PS(-) lipids, they induce substantial structural differences in lipid bilayers containing each of these cations. In other words, these cations have strong ion-specific effects on the structure of PS(-) membranes. This interpretation is supported by all-atomic molecular-dynamics simulations showing that Ca(2+) and Mg(2+) cations have different binding sites and induce different membrane hydration. We show that although both ions are incorporated deep into the hydrophilic region of the membrane, they have different positions and configurations at the membrane. Absorbed Ca(2+) cations present a peak at a distance ~2 nm from the center of the lipid bilayer, and their most probable binding configuration involves two oxygen atoms from each of the charged moieties of the PS molecule (phosphate and carboxyl groups). In contrast, the distribution of absorbed Mg(2+) cations has two different peaks, located a few angstroms before and after the Ca(2+) peak. The most probable configurations (corresponding to these two peaks) involve binding to two oxygen atoms from carboxyl groups (the most superficial binding peak) or two oxygen atoms from phosphate groups (the most internal peak). Moreover, simulations also show differences in the hydration structure of the membrane: we obtained a hydration of 7.5 and 9 water molecules per lipid in simulations with Ca(2+) and Mg(2

  18. Effect of Calcium and Magnesium on Phosphatidylserine Membranes: Experiments and All-Atomic Simulations

    PubMed Central

    Martín-Molina, Alberto; Rodríguez-Beas, César; Faraudo, Jordi

    2012-01-01

    It is known that phosphatidylserine (PS−) lipids have a very similar affinity for Ca2+ and Mg2+ cations, as revealed by electrokinetic and stability experiments. However, despite this similar affinity, experimental evidence shows that the presence of Ca2+ or Mg2+ induces very different aggregation behavior for PS− liposomes as characterized by their fractal dimensions. Also, turbidity measurements confirm substantial differences in aggregation behavior depending on the presence of Ca2+ or Mg2+ cations. These puzzling results suggest that although these two cations have a similar affinity for PS− lipids, they induce substantial structural differences in lipid bilayers containing each of these cations. In other words, these cations have strong ion-specific effects on the structure of PS− membranes. This interpretation is supported by all-atomic molecular-dynamics simulations showing that Ca2+ and Mg2+ cations have different binding sites and induce different membrane hydration. We show that although both ions are incorporated deep into the hydrophilic region of the membrane, they have different positions and configurations at the membrane. Absorbed Ca2+ cations present a peak at a distance ∼2 nm from the center of the lipid bilayer, and their most probable binding configuration involves two oxygen atoms from each of the charged moieties of the PS molecule (phosphate and carboxyl groups). In contrast, the distribution of absorbed Mg2+ cations has two different peaks, located a few angstroms before and after the Ca2+ peak. The most probable configurations (corresponding to these two peaks) involve binding to two oxygen atoms from carboxyl groups (the most superficial binding peak) or two oxygen atoms from phosphate groups (the most internal peak). Moreover, simulations also show differences in the hydration structure of the membrane: we obtained a hydration of 7.5 and 9 water molecules per lipid in simulations with Ca2+ and Mg2+, respectively. PMID:22824273

  19. Phosphatidylserine and Phosphatidylethanolamine Bind to Protein Z Cooperatively and with Equal Affinity

    PubMed Central

    Sengupta, Tanusree; Manoj, Narayanan

    2016-01-01

    Protein Z (PZ) is an anticoagulant that binds with high affinity to Protein Z-dependent protease inhibitor (ZPI) and accelerates the rate of ZPI-mediated inhibition of factor Xa (fXa) by more than 1000-fold in the presence of Ca2+ and phospholipids. PZ promotion of the ZPI-fXa interaction results from the anchoring of the Gla domain of PZ onto phospholipid surfaces and positioning the bound ZPI in close proximity to the Gla-anchored fXa, forming a ternary complex of PZ/ZPI/fXa. Although interaction of PZ with phospholipid membrane appears to be absolutely crucial for its cofactor activity, little is known about the binding of different phospholipids to PZ. The present study was conceived to understand the interaction of different phospholipids with PZ. Experiments with both soluble lipids and model membranes revealed that PZ binds to phosphatidylserine (PS) and phosphatidylethanolamine (PE) with equal affinity (Kd~48 μM); further, PS and PE bound to PZ synergistically. Equilibrium dialysis experiments revealed two lipid-binding sites for both PS and PE. PZ binds with weaker affinity to other phospholipids, e.g., phosphatidic acid, phosphatidylglycerol, phosphatidylcholine and binding of these lipids is not synergistic with respect to PS. Both PS and PE -containing membranes supported the formation of a fXa-PZ complex. PZ protection of fXa from antithrombin inhibition were also shown to be comparable in presence of both PS: PC and PE: PC membranes. These findings are particularly important and intriguing since they suggest a special affinity of PZ, in vivo, towards activated platelets, the primary membrane involved in blood coagulation process. PMID:27584039

  20. Anti-phosphatidylserine/prothrombin antibodies: an additional diagnostic marker for APS?

    PubMed

    Pregnolato, Francesca; Chighizola, Cecilia B; Encabo, Susan; Shums, Zakera; Norman, Gary L; Tripodi, Armando; Chantarangkul, Veena; Bertero, Tiziana; De Micheli, Valeria; Borghi, Maria Orietta; Meroni, Pier Luigi

    2013-07-01

    Among the diagnostic assays for anti-phospholipid syndrome (APS), lupus anticoagulant (LA) is the strongest predictor of thrombosis; however, it presents several limitations as interference with anticoagulant therapy and poor inter-laboratory agreement. Two-thirds of LA activity is apparently due to antibodies against prothrombin (PT), usually detectable by ELISA. Binding of PT to phosphatidylserine (PS) has been shown to enhance solid-phase anti-PT assay sensitivity. To determine the prevalence of antibodies against PS/PT (aPS/PT) in APS, we tested the semiquantitative QUANTA Lite(®) aPS/PT ELISA in a cohort of 80 APS patients. The prevalence of aPS/PT was 81.3%, rising to 87.6% when considering LA-positive subjects only. We observed a strong correlation between aPS/PT and LA (p = 0.006). To note, APS patients with thrombotic manifestations displayed significantly higher IgG aPS/PT titers compared to 20 aPL asymptomatic carriers (p = 0.012). To rule out a possible cross-reactivity of anti-β2 glycoprotein I antibodies (aβ2GPI) with PS/PT complex, we tested two monoclonal aβ2GPI antibodies and an affinity-purified (AP) polyclonal aβ2GPI IgG obtained from the serum of a patient reacting against both β2GPI and PS/PT. The two monoclonal antibodies did not show any reactivity against PS/PT complex, similarly the AP IgGs did not react toward PS/PT antigen while preserved their aβ2GPI activity. Our findings suggest that aPS/PT are a definite antibody population in APS. Moreover, the good correlation between aPS/PT ELISA and LA may support its use as a surrogate test for LA, particularly useful to overcome the technical limitations of the functional assay.

  1. Enhanced Eryptosis Following Gramicidin Exposure

    PubMed Central

    Malik, Abaid; Bissinger, Rosi; Liu, Guoxing; Liu, Guilai; Lang, Florian

    2015-01-01

    The peptide antibiotic and ionophore gramicidin has previously been shown to trigger apoptosis of nucleated cells. In analogy to apoptosis, the suicidal death of erythrocytes or eryptosis involves cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include oxidative stress, increase of cytosolic Ca2+ activity ([Ca2+]i), and ceramide. The present study explored, whether gramicidin triggers eryptosis. To this end phosphatidylserine exposure at the cell surface was estimated from annexin V binding, cell volume from forward scatter, red blood cell distribution width (RDW) from electronic particle counting, reactive oxidant species (ROS) from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence, [Ca2+]i from Fluo3- and Fluo4 fluorescence, and ceramide abundance from binding of specific antibodies. As a result, a 24 h exposure of human erythrocytes to gramicidin significantly increased the percentage of annexin-V-binding cells (≥1 µg/mL), forward scatter (≥0.5 µg/mL) and hemolysis. Gramicidin enhanced ROS activity, [Ca2+]i and ceramide abundance at the erythrocyte surface. The stimulation of annexin-V-binding by gramicidin was significantly blunted but not abolished by removal of extracellular Ca2+. In conclusion, gramicidin stimulates phospholipid scrambling of the erythrocyte cell membrane, an effect at least partially due to induction of oxidative stress, increase of [Ca2+]i and up-regulation of ceramide abundance. Despite increase of [Ca2+]i, gramicidin increases cell volume and slightly reduces RWD. PMID:25915718

  2. Enhanced eryptosis following gramicidin exposure.

    PubMed

    Malik, Abaid; Bissinger, Rosi; Liu, Guoxing; Liu, Guilai; Lang, Florian

    2015-04-23

    The peptide antibiotic and ionophore gramicidin has previously been shown to trigger apoptosis of nucleated cells. In analogy to apoptosis, the suicidal death of erythrocytes or eryptosis involves cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include oxidative stress, increase of cytosolic Ca2+ activity ([Ca2+]i), and ceramide. The present study explored, whether gramicidin triggers eryptosis. To this end phosphatidylserine exposure at the cell surface was estimated from annexin V binding, cell volume from forward scatter, red blood cell distribution width (RDW) from electronic particle counting, reactive oxidant species (ROS) from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence, [Ca2+]i from Fluo3- and Fluo4 fluorescence, and ceramide abundance from binding of specific antibodies. As a result, a 24 h exposure of human erythrocytes to gramicidin significantly increased the percentage of annexin-V-binding cells (≥1 µg/mL), forward scatter (≥0.5 µg/mL) and hemolysis. Gramicidin enhanced ROS activity, [Ca2+]i and ceramide abundance at the erythrocyte surface. The stimulation of annexin-V-binding by gramicidin was significantly blunted but not abolished by removal of extracellular Ca2+. In conclusion, gramicidin stimulates phospholipid scrambling of the erythrocyte cell membrane, an effect at least partially due to induction of oxidative stress, increase of [Ca2+]i and up-regulation of ceramide abundance. Despite increase of [Ca2+]i, gramicidin increases cell volume and slightly reduces RWD.

  3. Neuritin reverses deficits in murine novel object associative recognition memory caused by exposure to extremely low-frequency (50 Hz) electromagnetic fields

    PubMed Central

    Zhao, Qian-Ru; Lu, Jun-Mei; Yao, Jin-Jing; Zhang, Zheng-Yu; Ling, Chen; Mei, Yan-Ai

    2015-01-01

    Animal studies have shown that electromagnetic field exposure may interfere with the activity of brain cells, thereby generating behavioral and cognitive disturbances. However, the underlying mechanisms and possible preventions are still unknown. In this study, we used a mouse model to examine the effects of exposure to extremely low-frequency (50 Hz) electromagnetic fields (ELF MFs) on a recognition memory task and morphological changes of hippocampal neurons. The data showed that ELF MFs exposure (1 mT, 12 h/day) induced a time-dependent deficit in novel object associative recognition memory and also decreased hippocampal dendritic spine density. This effect was observed without corresponding changes in spontaneous locomotor activity and was transient, which has only been seen after exposing mice to ELF MFs for 7-10 days. The over-expression of hippocampal neuritin, an activity-dependent neurotrophic factor, using an adeno-associated virus (AAV) vector significantly increased the neuritin level and dendritic spine density. This increase was paralleled with ELF MFs exposure-induced deficits in recognition memory and reductions of dendritic spine density. Collectively, our study provides evidence for the association between ELF MFs exposure, impairment of recognition memory, and resulting changes in hippocampal dendritic spine density. Neuritin prevented this ELF MFs-exposure-induced effect by increasing the hippocampal spine density. PMID:26138388

  4. Neuritin reverses deficits in murine novel object associative recognition memory caused by exposure to extremely low-frequency (50 Hz) electromagnetic fields.

    PubMed

    Zhao, Qian-Ru; Lu, Jun-Mei; Yao, Jin-Jing; Zhang, Zheng-Yu; Ling, Chen; Mei, Yan-Ai

    2015-01-01

    Animal studies have shown that electromagnetic field exposure may interfere with the activity of brain cells, thereby generating behavioral and cognitive disturbances. However, the underlying mechanisms and possible preventions are still unknown. In this study, we used a mouse model to examine the effects of exposure to extremely low-frequency (50 Hz) electromagnetic fields (ELF MFs) on a recognition memory task and morphological changes of hippocampal neurons. The data showed that ELF MFs exposure (1 mT, 12 h/day) induced a time-dependent deficit in novel object associative recognition memory and also decreased hippocampal dendritic spine density. This effect was observed without corresponding changes in spontaneous locomotor activity and was transient, which has only been seen after exposing mice to ELF MFs for 7-10 days. The over-expression of hippocampal neuritin, an activity-dependent neurotrophic factor, using an adeno-associated virus (AAV) vector significantly increased the neuritin level and dendritic spine density. This increase was paralleled with ELF MFs exposure-induced deficits in recognition memory and reductions of dendritic spine density. Collectively, our study provides evidence for the association between ELF MFs exposure, impairment of recognition memory, and resulting changes in hippocampal dendritic spine density. Neuritin prevented this ELF MFs-exposure-induced effect by increasing the hippocampal spine density. PMID:26138388

  5. Reversible long-term changes in auditory processing in mature auditory cortex in the absence of hearing loss induced by passive, moderate-level sound exposure.

    PubMed

    Pienkowski, Martin; Eggermont, Jos J

    2012-01-01

    It has become increasingly clear that even occasional exposure to loud sounds in occupational or recreational settings can cause irreversible damage to the hair cells of the cochlea and the auditory nerve fibers, even if the resulting partial loss of hearing sensitivity, usually accompanied by tinnitus, disappears within hours or days of the exposure. Such exposure may explain at least some cases of poor speech intelligibility in noise in the face of a normal or near-normal audiogram. Recent findings from our laboratory suggest that long-term changes to auditory brain function-potentially leading to problems with speech intelligibility-can be effected by persistent, passive exposure to more moderate levels of noise (in the 70 dB SPL range) in the apparent absence of damage to the auditory periphery (as reflected in normal distortion product otoacoustic emissions and auditory brainstem responses). Specifically, passive exposure of adult cats to moderate levels of band-pass-filtered noise, or to band-limited ensembles of dense, random tone pips, can lead to a profound decrease of neural activity in the auditory cortex roughly in the exposure frequency range, and to an increase of activity outside that range. This can progress to an apparent reorganization of the cortical tonotopic map, which is reminiscent of the reorganization resulting from hearing loss restricted to a part of the hearing frequency range, although again, no hearing loss was apparent after our moderate-level sound exposure. Here, we review this work focusing specifically on the potential hearing problems that may arise despite a normally functioning auditory periphery.

  6. Antibodies against Native and Oxidized Cardiolipin and Phosphatidylserine and Phosphorylcholine in Atherosclerosis Development

    PubMed Central

    Frostegård, Anna G.; Su, Jun; Hua, Xiang; Vikström, Max; de Faire, Ulf; Frostegård, Johan

    2014-01-01

    Background Antibodies against cardiolipin and phosphatidylserine (anti-CL and anti-PS) are associated with thrombosis. In contrast, we determined that IgM antibodies against oxidized CL and PS (OxCL and OxPS) and phosphorylcholine (anti-PC) could be protection markers for cardiovascular disease (CVD). Methods 226 individuals with established hypertension (diastolic pressure>95 mmHg) from the European Lacidipine Study on Atherosclerosis. Antibodies were tested by ELISA. As a surrogate measure of atherosclerosis, the mean of the maximum intima-media thicknesses (IMT) in the far walls of common carotids and bifurcations was determined by ultrasonography at the time of inclusion and 4 years following inclusion. Results Increases in IMT measures at follow-up were significantly less common in subjects which at baseline had high IgM anti-OxPS and anti-PC at above 75th percentile: OR 0,45, CI (0,23–0,86) and OR 0.37, CI (0,19–0,71), p = 0.0137 respectively and above 90th percentile: OR 0.32, CI (0,12–0,84) and OR 0.39, CI (0,15–1.00), p = 0.050 and OR 0,22, CI (0,08–0,59) p = 0,0029. IgM anti-OxCL was negatively associated with IMT increases (OR, 0.32, CI (0,12–0,84), p = 0231). There were no associations for IgM anti-PS or anti-CL. Anti-PC, as determined herein by a commercial ELISA, was strongly associated with data from our previously published in house ELISA (R = 0,87; p<0,0001).) Anti-PC was also a risk marker at low levels (below 25th percentile; OR = 2,37 (1,16–4,82), p = 0,0177). Conclusions High levels of IgM anti-OxPS and anti-OxCL, but not traditional anti-phospholipid antibodies (anti-PS and anti-CL), are associated with protection against atherosclerosis development. In addition, low IgM anti-PC was a risk marker but high a protection marker. PMID:25473948

  7. Are DNA-damaging effects induced by herbicide formulations (Roundup® and Garlon®) in fish transient and reversible upon cessation of exposure?

    PubMed

    Guilherme, S; Santos, M A; Gaivão, I; Pacheco, M

    2014-10-01

    Owing to the seasonality of crop cultivation and subsequent periodic/seasonal application of herbicides, their input to the aquatic systems is typically intermittent. Consequently, exposure of fish to this type of contaminants can be short and followed by a period of permanence in non-contaminated areas. Thus, the assessment of genotoxic endpoints in fish after removal of the contamination source appears as a crucial step to improve the knowledge on the dynamics of herbicide genotoxicity, as well as to determine the actual magnitude of risk posed by these agrochemicals. Therefore, the present study intended to shed light on the ability of fish to recover from the DNA damage induced by short-term exposures to the herbicide formulations Roundup(®) (glyphosate-based) and Garlon(®) (triclopyr-based) upon the exposure cessation. European eel (Anguilla anguilla) was exposed to the above commercial formulations for 3 days, and allowed to recover for 1, 7 and 14 days (post-exposure period). The comet assay was used to identify the DNA damage in blood cells during both exposure and post-exposure periods. As an attempt to clarify the DNA damaging mechanisms involved, an extra-step including the incubation of the nucleotides with DNA lesion-specific repair enzyme was added to the standard comet. The genotoxic potential of both herbicides was confirmed, concerning the exposure period. In addition, the involvement of oxidative DNA damage on the action of Roundup(®) (pointed out as pyrimidine bases oxidation) was demonstrated, while for Garlon(®) this damaging mechanism was less evident. Fish exposed to Garlon(®), though presenting some evidence towards a tendency of recovery, did not achieve a complete restoration of DNA integrity. In what concerns to Roundup(®), a recovery was evident when considering non-specific DNA damage on day 14 post-exposure. In addition, this herbicide was able to induce a late oxidative DNA damage (day 14). Blood cells of A. anguilla exposed to

  8. Reversible dementias

    PubMed Central

    Tripathi, Manjari; Vibha, Deepti

    2009-01-01

    In recent years, more attention has been given to the early diagnostic evaluation of patients with dementia which is essential to identify patients with cognitive symptoms who may have treatable conditions. Guidelines suggest that all patients presenting with dementia or cognitive symptoms should be evaluated with a range of laboratory tests, and with structural brain imaging with computed tomography (CT) or magnetic resonance imaging (MRI). While many of the disorders reported as ‘reversible dementias’ are conditions that may well be associated with cognitive or behavioral symptoms, these symptoms are not always sufficiently severe to fulfill the clinical criteria for dementia. Thus, while the etiology of a condition may be treatable it should not be assumed that the associated dementia is fully reversible. Potentially reversible dementias should be identified and treatment considered, even if the symptoms are not sufficiently severe to meet the clinical criteria for dementia, and even if partial or full reversal of the cognitive symptoms cannot be guaranteed. In the literature, the most frequently observed potentially reversible conditions identified in patients with cognitive impairment or dementia are depression, adverse effects of drugs, drug or alcohol abuse, space-occupying lesions, normal pressure hydrocephalus, and metabolic conditions land endocrinal conditions like hypothyroidism and nutritional conditions like vitamin B-12 deficiency. Depression is by far the most common of the potentially reversible conditions. The review, hence addresses the common causes of reversible dementia and the studies published so far. PMID:21416018

  9. Reversible Sterilization

    ERIC Educational Resources Information Center

    Largey, Gale

    1977-01-01

    Notes that difficult questions arise concerning the use of sterilization for alleged eugenic and euthenic purposes. Thus, how reversible sterilization will be used with relation to the poor, mentally ill, mentally retarded, criminals, and minors, is questioned. (Author/AM)

  10. Reversible Cardiomyopathies

    PubMed Central

    Patel, Harsh; Madanieh, Raef; Kosmas, Constantine E; Vatti, Satya K; Vittorio, Timothy J

    2015-01-01

    Cardiomyopathies (CMs) have many etiological factors that can result in severe structural and functional dysregulation. Fortunately, there are several potentially reversible CMs that are known to improve when the root etiological factor is addressed. In this article, we discuss several of these reversible CMs, including tachycardia-induced, peripartum, inflammatory, hyperthyroidism, Takotsubo, and chronic illness–induced CMs. Our discussion also includes a review on their respective pathophysiology, as well as possible management solutions. PMID:26052233

  11. Rat exposure in mice with neuropathic pain induces fear and antinociception that is not reversed by 5-HT2C receptor activation in the dorsal periaqueductal gray.

    PubMed

    Furuya-da-Cunha, Elke Mayumi; Souza, Rimenez Rodrigues de; Canto-de-Souza, Azair

    2016-07-01

    Previous studies have demonstrated that serotonin 5-HT2C receptors in the dorsal periaqueductal gray (dPAG) mediate both anxiety and antinociception in mice submitted to the elevated plus maze. The present study examined the effects of intra-dPAG infusion of the serotonin 5-HT2C receptor agonist (MK-212) in the defensive reactions and antinociception in mice with neurophatic pain confronted by a predator. Neuropathic pain was induced by chronic constriction injury (CCI) of the sciatic nerve, and predator confrontation was performed using the rat exposure test (RET). Our results demonstrated that both sham-operated and CCI mice exhibited intense defensive reactions when confronted by rats. However, rat-exposed CCI mice showed reduced pain reactivity in comparison to CCI mice exposed to a toy rat. Intra-dPAG infusion of MK-212 prior to predator exposure did not significantly alter defensive or antinociceptive responses. To our knowledge, our results represent the first evidence of RET-induced antinociception in mice. Moreover, the results of the present study suggest that 5-HT2C receptor activation in the dPAG is not critically involved in the control of predator-evoked fearful or antinociceptive responses. PMID:27059332

  12. Reversible effect of maternal exposure to chlorpyrifos on the intermediate granule cell progenitors in the hippocampal dentate gyrus of rat offspring.

    PubMed

    Ohishi, Takumi; Wang, Liyun; Akane, Hirotoshi; Itahashi, Megu; Nakamura, Daichi; Yafune, Atsunori; Mitsumori, Kunitoshi; Shibutani, Makoto

    2013-01-01

    To examine the effects of developmental exposure to chlorpyrifos (CPF) on neurogenesis in the hippocampal dentate gyrus, pregnant rats were treated with 2.8, 14 or 70 ppm CPF in the diet from gestational day 10 to day 21 after delivery. Dams had decreased cholinesterase (ChE) activities in red blood cells (RBC) at intakes of ≥2.8 ppm and in brain at 70 ppm. Offspring on postnatal day (PND) 21 had decreased ChE activities in the RBC and brain at 70 ppm. There were no behavioral abnormalities in the offspring. Immunohistochemical analysis showed decreases in the numbers of cells positive for proliferating cell nuclear antigen and T box brain 2 in the subgranular zone (SGZ) of the dentate gyrus on PND 21 at 70 ppm, while other progenitor cell populations and the apoptotic cell number were unaffected in this zone. However, on PND 77 all changes had disappeared. The distribution of the progenitor cell population expressing nicotinic acetylcholine receptor α7 and lacking expression of postmitotic neuron-specific nuclear protein was unchanged by CPF-exposure, suggesting no effect of cholinergic stimulation on neurogenesis. These results suggest that developmental exposure to CPF directly but transiently affect the proliferation of type-2 progenitor cell populations in the hippocampal neurogenesis. The lowest-observed-adverse-effect level (LOAEL) of CPF was determined to be 2.8 ppm (0.36 mg/kg body weight/day) for dams by the inhibition of ChE activity in the RBC at this dose. As for offspring, no-observed-adverse-effect level (NOAEL) was determined to be 14 ppm (1.86 mg/kg body weight/day) by the decrease of type-2 progenitor cell proliferation in the SGZ and the inhibition of ChE activity in the RBC and brain at 70 ppm. The NOAEL of dams based on the offspring's effects was approximately 2800 times higher than the estimated consumption of CPF through food in the general population and in pregnant women as examined in Japan.

  13. INTRACELLULAR TRANSPORT. PI4P/phosphatidylserine countertransport at ORP5- and ORP8-mediated ER-plasma membrane contacts.

    PubMed

    Chung, Jeeyun; Torta, Federico; Masai, Kaori; Lucast, Louise; Czapla, Heather; Tanner, Lukas B; Narayanaswamy, Pradeep; Wenk, Markus R; Nakatsu, Fubito; De Camilli, Pietro

    2015-07-24

    Lipid transfer between cell membrane bilayers at contacts between the endoplasmic reticulum (ER) and other membranes help to maintain membrane lipid homeostasis. We found that two similar ER integral membrane proteins, oxysterol-binding protein (OSBP)-related protein 5 (ORP5) and ORP8, tethered the ER to the plasma membrane (PM) via the interaction of their pleckstrin homology domains with phosphatidylinositol 4-phosphate (PI4P) in this membrane. Their OSBP-related domains (ORDs) harbored either PI4P or phosphatidylserine (PS) and exchanged these lipids between bilayers. Gain- and loss-of-function experiments showed that ORP5 and ORP8 could mediate PI4P/PS countertransport between the ER and the PM, thus delivering PI4P to the ER-localized PI4P phosphatase Sac1 for degradation and PS from the ER to the PM. This exchange helps to control plasma membrane PI4P levels and selectively enrich PS in the PM.

  14. New tests to detect antiphospholipid antibodies: antiprothrombin (aPT) and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies.

    PubMed

    Sciascia, Savino; Khamashta, Munther A; Bertolaccini, Maria Laura

    2014-05-01

    Antiprothrombin antibodies have been proposed as potential new biomarkers for thrombosis and/or pregnancy morbidity in the setting of the antiphospholipid syndrome (APS). Antiprothrombin antibodies are commonly detected by ELISA, using prothrombin coated onto irradiated plates (aPT), or prothrombin in complex with phosphatidylserine (aPS/PT), as antigen. Although these antibodies can co-exist in the same patient, aPT and aPS/PT seem to belong to different populations of autoantibodies. Early research explored the role of antibodies to prothrombin as potential antigenic targets for the lupus anticoagulant (LA). To date their clinical significance is being investigated and their potential role in identifying patients at higher risk of developing thrombotic events or pregnancy morbidity is being probed.

  15. Simulations of nanopore formation and phosphatidylserine externalization in lipid membranes subjected to a high-intensity, ultrashort electric pulse.

    PubMed

    Hu, Q; Joshi, R P; Schoenbach, K H

    2005-09-01

    A combined MD simulator and time dependent Laplace solver are used to analyze the electrically driven phosphatidylserine externalization process in cells. Time dependent details of nanopore formation at cell membranes in response to a high-intensity (100 kV/cm), ultrashort (10 ns) electric pulse are also probed. Our results show that nanosized pores could typically be formed within about 5 ns. These predictions are in very good agreement with recent experimental data. It is also demonstrated that defect formation and PS externalization in membranes should begin on the anode side. Finally, the simulations confirm that PS externalization is a nanopore facilitated event, rather than the result of molecular translocation across the trans-membrane energy barrier.

  16. Simulations of nanopore formation and phosphatidylserine externalization in lipid membranes subjected to a high-intensity, ultrashort electric pulse

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Joshi, R. P.; Schoenbach, K. H.

    2005-09-01

    A combined MD simulator and time dependent Laplace solver are used to analyze the electrically driven phosphatidylserine externalization process in cells. Time dependent details of nanopore formation at cell membranes in response to a high-intensity (100kV/cm) , ultrashort (10ns) electric pulse are also probed. Our results show that nanosized pores could typically be formed within about 5ns . These predictions are in very good agreement with recent experimental data. It is also demonstrated that defect formation and PS externalization in membranes should begin on the anode side. Finally, the simulations confirm that PS externalization is a nanopore facilitated event, rather than the result of molecular translocation across the trans-membrane energy barrier.

  17. Aspirin induces cell death and caspase-dependent phosphatidylserine externalization in HT-29 human colon adenocarcinoma cells

    PubMed Central

    Castaño, E; Dalmau, M; Barragán, M; Pueyo, G; Bartrons, R; Gil, J

    1999-01-01

    The induction of cell death by aspirin was analysed in HT-29 colon carcinoma cells. Aspirin induced two hallmarks of apoptosis: nuclear chromatin condensation and increase in phosphatidylserine externalization. However, aspirin did not induce either oligonucleosomal fragmentation of DNA, decrease in DNA content or nuclear fragmentation. The effect of aspirin on Annexin V binding was inhibited by the caspase inhibitor Z-VAD.fmk, indicating the involvement of caspases in the apoptotic action of aspirin. However, aspirin did not induce proteolysis of PARP, suggesting that aspirin does not increase nuclear caspase 3-like activity in HT-29 cells. This finding may be related with the ‘atypical’ features of aspirin-induced apoptosis in HT-29 cells. © 1999 Cancer Research Campaign PMID:10496355

  18. Increased excitability of medium-sized dorsal root ganglion neurons by prolonged interleukin-1β exposure is K+ channel dependent and reversible

    PubMed Central

    Stemkowski, Patrick L; Noh, Myung-chul; Chen, Yishen; Smith, Peter A

    2015-01-01

    Chronic constriction injury of rat sciatic nerve promotes signs of neuropathic pain. This is associated with an increase in the level of interleukin 1β (IL-1β) in primary afferents that peaks at 7 days. This initial cytokine exposure has been proposed to trigger an enduring alteration in neuronal phenotype that underlies chronic hyper-excitability in sensory nerves, which initiates and maintains chronic neuropathic pain. We have shown previously that 5–6 days of exposure of rat dorsal root ganglia (DRGs) to 100 pm IL-1β increases the excitability of medium-sized neurons. We have now found using whole-cell recording that this increased excitability reverts to control levels within 3–4 days of cytokine removal. The effects of IL-1β were dominated by changes in K+ currents. Thus, the amplitudes of A-current, delayed rectifier and Ca2+-sensitive K+ currents were reduced by ∼68%, ∼64% and ∼36%, respectively. Effects of IL-1β on other cation currents were modest by comparison. There was thus a slight decrease in availability of high voltage-activated Ca2+ channel current, a small increase in rates of activation of hyperpolarization-activated cyclic nucleotide-gated channel current (IH), and a shift in the voltage dependence of activation of tetrodotoxin-sensitive sodium current (TTX-S INa) to more negative potentials. It is unlikely, therefore, that direct interaction of IL-1β with DRG neurons initiates an enduring phenotypic shift in their electrophysiological properties following sciatic nerve injury. Persistent increases in primary afferent excitability following nerve injury may instead depend on altered K+ channel function and on the continued presence of slightly elevated levels IL-1β and other cytokines. PMID:26110238

  19. In Utero Exposure to a Cardiac Teratogen Causes Reversible Deficits in Postnatal Cardiovascular Function, But Altered Adaptation to the Burden of Pregnancy.

    PubMed

    Aasa, Kristiina L; Maciver, Rebecca D; Ramchandani, Shyamlal; Adams, Michael A; Ozolinš, Terence R S

    2015-11-01

    Congenital heart defects (CHD) are the most common birth anomaly and while many resolve spontaneously by 1 year of age, the lifelong burden on survivors is poorly understood. Using a rat model of chemically induced CHD that resolve postnatally, we sought to characterize the postnatal changes in cardiac function, and to investigate whether resolved CHD affects the ability to adapt to the increased the cardiovascular (CV) burden of pregnancy. To generate rats with resolved CHD, pregnant rats were administered distilled water or dimethadione (DMO) [300 mg/kg b.i.d. on gestation day (gd) 9 and 10] and pups delivered naturally. To characterize structural and functional changes in the heart, treated and control offspring were scanned by echocardiography on postnatal day 4, 21, and 10-12 weeks. Radiotelemeters were implanted for continuous monitoring of hemodynamics. Females were mated and scanned by echocardiography on gd12 and gd18 during pregnancy. On gd18, maternal hearts were collected for structural and molecular assessment. Postnatal echocardiography revealed numerous structural and functional differences in treated offspring compared with control; however, these resolved by 10-12 weeks of age. The CV demand of pregnancy revealed differences between treated and control offspring with respect to mean arterial pressure, CV function, cardiac strain, and left ventricular gene expression. In utero exposure to DMO also affected the subsequent generation. Gd18 fetal and placental weights were increased in treated F2 offspring. This study demonstrates that in utero chemical exposure may permanently alter the capacity of the postnatal heart to adapt to pregnancy and this may have transgenerational effects.

  20. The nicotinic acetylcholine receptor: Binding of nitroxide analogs of a local anesthetic and a photoactivatable analog of phosphatidylserine

    SciTech Connect

    Blanton, M.P.

    1989-01-01

    Electron spin resonance was used to contrast the accessibility of tertiary and quaternary amine local anesthetics to their high affinity binding site in the desensitized Torpedo californica acetylcholine receptor (AchR). Preincubation of AchR-rich membranes with agonist resulted in a substantial reduction in the initial association of the quaternary amine local anesthetic C6SLMEI with the receptor. The time-dependent reduction in association follows a biphasic exponential function having rate constants of 0.19 min{sup {minus}1} and 0.03 min{sup {minus}1}. In contrast, agonist preincubation did not produce a comparable decrease in the association of C6SL, a tertiary amine analog, with the AchR. The results are modeled in two ways: (1) A charge gate near the channel mouth in the desensitized receptor limits access of the permanently charged cationic local anesthetic (C6SLMEI), but not for the uncharged form of the tertiary amine anesthetic C6SL. (2) A hydrophobic pathway, possibly through a corridor in the annular lipid surrounding receptor subunits, allows the uncharged form of C6SL to reach the high affinity binding site in the AchR. A photoactivatable analog of phosphatidylserine {sup 125}I 4-azido salicylic acid-phosphatidylserine ({sup 125}I ASA-PS) was use to label both Torpedo californica acetylcholine receptor-rich membranes and reconstituted AchR membranes. All four subunits of the AchR were found to incorporate label, with the {alpha} subunit incorporating approximately twice as much as each of the other subunits on a per mole basis. The regions of the AchR {alpha} subunit that incorporate {sup 125}I ASA-PS were mapped by Staphylococcus aureus V8 protease digestion. Eighty-one per cent of the incorporated label was localized to 11.7 and 10.1 kdal V8 cleavage fragments.

  1. In vivo chronic nicotine exposure differentially and reversibly affects upregulation and stoichiometry of α4β2 nicotinic receptors in cortex and thalamus.

    PubMed

    Fasoli, F; Moretti, M; Zoli, M; Pistillo, F; Crespi, A; Clementi, F; Mc Clure-Begley, T; Marks, M J; Gotti, C

    2016-09-01

    Studies with heterologous expression systems have shown that the α4β2 nicotinic acetylcholine receptor (nAChR) subtype can exist in two stoichiometries (with two [(α4)2(β2)3] or three [(α4)3(β2)2] copies of the α subunit in the receptor pentamer) which have different pharmacological and functional properties and are differently regulated by chronic nicotine treatment. However, the effects of nicotine treatment in vivo on native α4β2 nAChR stoichiometry are not well known. We investigated in C57BL/6 mice the in vivo effect of 14-day chronic nicotine treatment and subsequent withdrawal, on the subunit expression and β2/α4 subunit ratio of (3)H-epibatidine labeled α4β2*-nAChR in total homogenates of cortex and thalamus. We found that in basal conditions the ratio of the β2/α4 subunit in the cortex and thalamus is different indicating a higher proportion in receptors with (α4)2(β2)3 subunit stoichiometry in the thalamus. For cortex exposure to chronic nicotine elicited an increase in receptor density measured by (3)H-epibatidine binding, an increase in the α4 and β2 protein levels, and an increase in β2/α4 subunit ratio, that indicates an increased proportion of receptors with the (α4)2(β2)3 stoichiometry. For thalamus we did not find a significant increase in receptor density, α4 and β2 protein levels, or changes in β2/α4 subunit ratio. All the changes elicited by chronic nicotine in cortex were transient and returned to basal levels with an average half-life of 2.8 days following nicotine withdrawal. These data suggest that chronic nicotine exposure in vivo favors increased assembly of α4β2 nAChR containing three β2 subunits. A greater change in stoichiometry was observed for cortex (which has relatively low basal expression of (α4)2(β2)3 nAChR) than in thalamus (which has a relatively high basal expression of (α4)2(β2)3 nAChR).

  2. Silicon Reverses Lipid Peroxidation but not Acetylcholinesterase Activity Induced by Long-Term Exposure to Low Aluminum Levels in Rat Brain Regions.

    PubMed

    Noremberg, Simone; Bohrer, Denise; Schetinger, Maria R C; Bairros, André V; Gutierres, Jessié; Gonçalves, Jamile F; Veiga, Marlei; Santos, Francielli W

    2016-01-01

    Aluminum (Al) is the most widely distributed metal in the environment and is extensively used in daily life leading to easy exposure to human beings. Besides not having a recognized physiological role, Al may produce adverse effects through the interaction with the cholinergic system contributing to oxidative stress. The present study evaluated, in similar conditions of parenteral nutrition, whether the reaction of silicon (SiO2) with Al(3+) to form hydroxyaluminosilicates (HAS) reduces its bioavailability and toxicity through intraperitoneal administrations of 0.5 mg Al/kg/day and/or 2 mg Si/kg/day in Wistar rats. Al and Si concentrations were determined in rat brain tissue and serum. Acetylcholinesterase (AChE) activity and lipid peroxidation (LPO) were analyzed in the cerebellum, cortex, hippocampus, striatum, hypothalamus, and blood. An increase in the Al concentration was verified in the Al + Si group in the brain. All the groups demonstrated enhanced Si compared to the control animals. Al(3+) increased LPO measured by thiobarbituric acid reactive substances (TBARS) in cerebellum and hippocampus, whereas SiO2 reduced it when compared with the control group. An increase of AChE activity was observed in the Al-treated group in the cerebellum whereas a decrease of this enzyme activity was observed in the cortex and hippocampus in the Al and Al + Si groups. Al and Si concentrations increased in rat serum; however, no effect was observed in blood TBARS levels and AChE activity. SiO2 showed a protective effect in the hippocampus and cerebellum against cellular damage caused by Al(3+)-induced lipid peroxidation. Thus, SiO2 may be considered an important protector in LPO induced by Al(3+).

  3. Reversible Chemochromic Hydrogen Detectors

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Florida Solar Energy Center (FSEC), affiliated with the University of Central Florida, has invented a reversible pigment that changes from light beige to blue when exposed to hydrogen and back to light beige when exposed to atmospheric oxygen. In laboratory and environmental studies, the FSEC pigment in its tape form failed to change color adequately when exposed to hydrogen after one day of exposure at Kennedy Space Center's Beach Corrosion Test Facility. The reversible hydrogen-detecting tape also lost its ability to change color after being placed in an environmental chamber at 45 C for one day. The first attempts at extruding the reversible pigment into various polymers were unsuccessful because of the pigment's poor thermal stability. The goal of this project was to formulate a pigment with improved thermal and environmental stability for extrusion into a variety of appropriate polymer matrices. The formulation of the reversible hydrogen-detecting pigment was modified by removing one reagent and chemically modifying the hydrogen sensitive ingredient. This was intended to improve the hydrophobicity of the pigment and alter the thermal degradation mechanism.

  4. Vasectomy reversal.

    PubMed

    Belker, A M

    1987-02-01

    A vasovasostomy may be performed on an outpatient basis with local anesthesia, but also may be performed on an outpatient basis with epidural or general anesthesia. Local anesthesia is preferred by most of my patients, the majority of whom choose this technique. With proper preoperative and intraoperative sedation, patients sleep lightly through most of the procedure. Because of the length of time often required for bilateral microsurgical vasoepididymostomy, epidural or general anesthesia and overnight hospitalization are usually necessary. Factors influencing the preoperative choice for vasovasostomy or vasoepididymostomy in patients undergoing vasectomy reversal are considered. The preoperative planned choice of vasovasostomy or vasoepididymostomy for patients having vasectomy reversal described herein does not have the support of all urologists who regularly perform these procedures. My present approach has evolved as the data reported in Tables 1 and 2 have become available, but it may change as new information is evaluated. However, it offers a logical method for planning choices of anesthesia and inpatient or outpatient status for patients undergoing vasectomy reversal procedures. PMID:3811050

  5. Vasectomy reversal.

    PubMed

    Belker, A M

    1987-02-01

    A vasovasostomy may be performed on an outpatient basis with local anesthesia, but also may be performed on an outpatient basis with epidural or general anesthesia. Local anesthesia is preferred by most of my patients, the majority of whom choose this technique. With proper preoperative and intraoperative sedation, patients sleep lightly through most of the procedure. Because of the length of time often required for bilateral microsurgical vasoepididymostomy, epidural or general anesthesia and overnight hospitalization are usually necessary. Factors influencing the preoperative choice for vasovasostomy or vasoepididymostomy in patients undergoing vasectomy reversal are considered. The preoperative planned choice of vasovasostomy or vasoepididymostomy for patients having vasectomy reversal described herein does not have the support of all urologists who regularly perform these procedures. My present approach has evolved as the data reported in Tables 1 and 2 have become available, but it may change as new information is evaluated. However, it offers a logical method for planning choices of anesthesia and inpatient or outpatient status for patients undergoing vasectomy reversal procedures.

  6. Integrated medicine and the prevention and reversal of memory loss.

    PubMed

    Khalsa, D S

    1998-11-01

    This article, based on scientific research and clinical observations, suggests that memory loss is not an inevitable consequence of aging and that Alzheimer's disease can be prevented and reversed using an integrated medical approach. Three new associations with memory loss other than age, heredity, and genetics are described. They include a high-fat diet, chronic unbalanced stress with its attendant risk in the adrenal hormone cortisol, and the presence of cardiovascular disease. A 4-pillar integrative medical program on brain longevity is presented. The program includes a diet consisting of 15% fat and supplementation with brain-specific nutrients such as vitamin B complex, vitamin E, ubiquinone, ginkgo biloba, and phosphatidylserine. In addition, stress-relieving meditation, mind-body and cognitive exercise, antiaging drugs like L-deprenyl citrate, as well as hormones such as dehydroepiandrosterone and pregnenolone complete the program. Patient benefits such as greater wisdom and spiritual happiness are also explored.

  7. Multiple stimulus reversible hydrogels

    DOEpatents

    Gutowska, Anna; Krzyminski, Karol J.

    2006-04-25

    A polymeric solution capable of gelling upon exposure to a critical minimum value of a plurality of environmental stimuli is disclosed. The polymeric solution may be an aqueous solution utilized in vivo and capable of having the gelation reversed if at least one of the stimuli fall below, or outside the range of, the critical minimum value. The aqueous polymeric solution can be used either in industrial or pharmaceutical environments. In the medical environment, the aqueous polymeric solution is provided with either a chemical or radioisotopic therapeutic agent for delivery to a specific body part. The primary advantage of the process is that exposure to one environmental stimuli alone will not cause gelation, thereby enabling the therapeutic agent to be conducted through the body for relatively long distances without gelation occurring.

  8. Multiple stimulus reversible hydrogels

    DOEpatents

    Gutowska, Anna; Krzyminski, Karol J.

    2003-12-09

    A polymeric solution capable of gelling upon exposure to a critical minimum value of a plurality of environmental stimuli is disclosed. The polymeric solution may be an aqueous solution utilized in vivo and capable of having the gelation reversed if at least one of the stimuli fall below, or outside the range of, the critical minimum value. The aqueous polymeric solution can be used either in industrial or pharmaceutical environments. In the medical environment, the aqueous polymeric solution is provided with either a chemical or radioisotopic therapeutic agent for delivery to a specific body part. The primary advantage of the process is that exposure to one environmental stimuli alone will not cause gelation, thereby enabling the therapeutic agent to be conducted through the body for relatively long distances without gelation occurring.

  9. The influence of dipalmitoyl phosphatidylserine on phase behaviour of and cellular response to lyotropic liquid crystalline dispersions.

    PubMed

    Shen, Hsin-Hui; Crowston, Jonathan G; Huber, Florian; Saubern, Simon; McLean, Keith M; Hartley, Patrick G

    2010-12-01

    Lyotropic liquid crystalline nanoparticles (cubosomes) have the potential to act as amphiphilic scaffolds for the presentation of lipids and subsequent application in, for example, bioseparations and therapeutic delivery. In this work we have formulated lyotropic liquid crystalline systems based on the synthetic amphiphile 1,2,3-trihydroxy-3,7,11,15-tetramethylhexadecane (phytantriol) and containing the lipid dipalmitoyl phosphatidylserine (DPPS). We have prepared a range of DPPS-containing phytantriol cubosome formulations and characterized them using Small Angle X-ray Scattering and Cryo-transmission electron microscopy. These techniques show that increased DPPS content induces marked changes in lyotropic liquid crystalline phase behaviour, characterized by changes in crystallographic dimensions and increases in vesicle content. Furthermore, in vitro cell culture studies indicate that these changes correlate with lipid/surfactant cellular uptake and cytotoxicity. A model cell membrane based on a surface supported phospholipid bilayer was used to gain insights into cubosome-bilayer interactions using Quartz Crystal Microgravimetry. The data show that mass uptake at the supported bilayer increased with DPPS content. We propose that the cytotoxicity of the DPPS-containing dispersions results from changes in lipid/surfactant phase behaviour and the preferential attachment and fusion of vesicles at the cell membrane.

  10. Phosphatidylserine (PS) Is Exposed in Choroidal Neovascular Endothelium: PS-Targeting Antibodies Inhibit Choroidal Angiogenesis In Vivo and Ex Vivo

    PubMed Central

    Li, Tao; Aredo, Bogale; Zhang, Kaiyan; Zhong, Xin; Pulido, Jose S.; Wang, Shusheng; He, Yu-Guang; Huang, Xianming; Brekken, Rolf A.; Ufret-Vincenty, Rafael L.

    2015-01-01

    Purpose Choroidal neovascularization (CNV) accounts for 90% of cases of severe vision loss in patients with advanced age-related macular degeneration. Identifying new therapeutic targets for CNV may lead to novel combination therapies to improve outcomes and reduce treatment burden. Our goal was to test whether phosphatidylserine (PS) becomes exposed in the outer membrane of choroidal neovascular endothelium, and whether this could provide a new therapeutic target for CNV. Methods Choroidal neovascularization was induced in C57BL/6J mice using laser photocoagulation. Choroidal neovascularization lesions costained for exposed PS and for intercellular adhesion molecule 2 (or isolectin B4) were imaged in flat mounts and in cross sections. The laser CNV model and a choroidal sprouting assay were used to test the effect of PS-targeting antibodies on choroidal angiogenesis. Choroidal neovascularization lesion size was determined by intercellular adhesion molecule 2 (ICAM-2) staining of flat mounts. Results We found that PS was exposed in CNV lesions and colocalized with vascular endothelial staining. Treatment with PS-targeting antibodies led to a 40% to 80% reduction in CNV lesion area when compared to treatment with a control antibody. The effect was the same as that seen using an equal dose of an anti-VEGF antibody. Results were confirmed using the choroid sprouting assay, an ex vivo model of choroidal angiogenesis. Conclusions We demonstrated that PS is exposed in choroidal neovascular endothelium. Furthermore, targeting this exposed PS with antibodies may be of therapeutic value in CNV. PMID:26529048

  11. Identification of lipid-phosphatidylserine (PS) as the target of unbiasedly selected cancer specific peptide-peptoid hybrid PPS1

    PubMed Central

    Desai, Tanvi J.; Toombs, Jason E.; Minna, John D.; Brekken, Rolf A.; Udugamasooriya, Damith Gomika

    2016-01-01

    Phosphatidylserine (PS) is an anionic phospholipid maintained on the inner-leaflet of the cell membrane and is externalized in malignant cells. We previously launched a careful unbiased selection targeting biomolecules (e.g. protein, lipid or carbohydrate) distinct to cancer cells by exploiting HCC4017 lung cancer and HBEC30KT normal epithelial cells derived from the same patient, identifying HCC4017 specific peptide-peptoid hybrid PPS1. In this current study, we identified PS as the target of PPS1. We validated direct PPS1 binding to PS using ELISA-like assays, lipid dot blot and liposome based binding assays. In addition, PPS1 recognized other negatively charged and cancer specific lipids such as phosphatidic acid, phosphatidylinositol and phosphatidylglycerol. PPS1 did not bind to neutral lipids such as phosphatidylethanolamine found in cancer and phosphatidylcholine and sphingomyelin found in normal cells. Further we found that the dimeric version of PPS1 (PPS1D1) displayed strong cytotoxicity towards lung cancer cell lines that externalize PS, but not normal cells. PPS1D1 showed potent single agent anti-tumor activity and enhanced the efficacy of docetaxel in mice bearing H460 lung cancer xenografts. Since PS and anionic phospholipid externalization is common across many cancer types, PPS1 may be an alternative to overcome limitations of protein targeted agents. PMID:27120792

  12. Novel function of stabilin-2 in myoblast fusion: the recognition of extracellular phosphatidylserine as a “fuse-me” signal

    PubMed Central

    Kim, Go-Woon; Park, Seung-Yoon; Kim, In-San

    2016-01-01

    Myoblast fusion is important for skeletal muscle formation. Even though the knowledge of myoblast fusion mechanism has accumulated over the years, the initial signal of fusion is yet to be elucidated. Our study reveals the novel function of a phosphatidylserine (PS) receptor, stabilin-2 (Stab2), in the modulation of myoblast fusion, through the recognition of PS exposed on myoblasts. During differentiation of myoblasts, Stab2 expression is higher than other PS receptors and is controlled by calcineurin/NFAT signaling on myoblasts. The forced expression of Stab2 results in an increase in myoblast fusion; genetic ablation of Stab2 in mice causes a reduction in muscle size, as a result of impaired myoblast fusion. After muscle injury, muscle regeneration is impaired in Stab2-deficient mice, resulting in small myofibers with fewer nuclei, which is due to reduction of fusion rather than defection of myoblast differentiation. The fusion-promoting role of Stab2 is dependent on its PS-binding motif, and the blocking of PS-Stab2 binding impairs cell-cell fusion on myoblasts. Given our previous finding that Stab2 recognizes PS exposed on apoptotic cells for sensing as an “eat-me” signal, we propose that PS-Stab2 binding is required for sensing of a “fuse-me” signal as the initial signal of myoblast fusion. [BMB Reports 2016; 49(6): 303-304] PMID:27174501

  13. Targeted detection of phosphatidylserine in biomimetic membranes and in vitro cell systems using annexin V-containing cubosomes.

    PubMed

    Shen, Hsin-Hui; Lake, Vanessa; Le Brun, Anton P; James, Michael; Duff, Anthony P; Peng, Yong; McLean, Keith M; Hartley, Patrick G

    2013-11-01

    In this work we have formulated Annexin V (ANX) decorated phosphatidylserine containing phytantriol (PSPhy) cubosomes to act as probes for the enhanced detection of apoptotic membranes in both model and in vitro cell systems. Small angle X-ray scattering (SAXS) and cryogenic-transmission electron microscopy (Cryo-TEM) indicated that ANX-containing PSPhy (ANX-PSPhy) cubosomes retain the Pn3m cubic symmetry and cubic phase nanoparticle characteristics of PSPhy cubosomes. The interaction of ANX-PSPhy cubosomes with apoptotic model and cellular membranes was also investigated using both quartz crystal microbalance with dissipation and confocal microscopy which confirmed that ANX-PSPhy cubosomes can selectively bind to apoptotic cells and model membranes. Neutron reflectometry has also been used to show strong binding of ANX-PSPhy cubosomes to a model apoptotic membrane, and in addition reveals changes in both the bilayer structure and in the internal structure of the cubosome in a region adjacent to the membrane as a result of material exchange. This material exchange between cubosome and apoptotic model bilayer was further demonstrated using Cryo-TEM. We have demonstrated that lipid bound protein, in this case Annexin V, can be used to target cubosome systems to biological surfaces in vitro.

  14. Characterization of phosphatidylserine-dependent beta2-glycoprotein I macrophage interactions. Implications for apoptotic cell clearance by phagocytes.

    PubMed

    Balasubramanian, K; Schroit, A J

    1998-10-30

    The binding and uptake of phosphatidylserine (PS)-expressing cells appears to involve multiple receptor-mediated systems that recognize the lipid either directly or indirectly through intermediate proteins that form a molecular bridge between the cells. Here we show that beta2-glycoprotein I (beta2GPI), a 50-kDa serum glycoprotein, binds PS-containing vesicles and serves as an intermediate for the interaction of these vesicles with macrophages. Chemical modification of lysines and cysteines abolished beta2GPI-dependent PS uptake by inhibiting the binding of PS to beta2GPI and the binding of PS.beta2GPI complex to macrophages, respectively. Recognition was mediated by beta2GPI and not by the lipid because antibodies to beta2GPI inhibited binding of the complex to macrophages. These results indicate that human (THP-1-derived) macrophages bind beta2GPI only after it is bound to its lipid ligand. Competition experiments with monosaccharides that inhibit lectin-dependent interactions, and PS.beta2GPI binding experiments using deglycosylated beta2GPI, suggested that carbohydrate residues were not required for macrophage recognition of the complex. Antibodies to putative macrophage PS receptors (CD36, CD68, and CD14) did not inhibit uptake of the complex. These data suggest that beta2GPI can bind cells that fail to maintain membrane lipid asymmetry and generate a specific bridging moiety that is recognized for clearance by a phagocyte receptor that is distinct from CD36, CD68, and CD14.

  15. Targeted detection of phosphatidylserine in biomimetic membranes and in vitro cell systems using annexin V-containing cubosomes.

    PubMed

    Shen, Hsin-Hui; Lake, Vanessa; Le Brun, Anton P; James, Michael; Duff, Anthony P; Peng, Yong; McLean, Keith M; Hartley, Patrick G

    2013-11-01

    In this work we have formulated Annexin V (ANX) decorated phosphatidylserine containing phytantriol (PSPhy) cubosomes to act as probes for the enhanced detection of apoptotic membranes in both model and in vitro cell systems. Small angle X-ray scattering (SAXS) and cryogenic-transmission electron microscopy (Cryo-TEM) indicated that ANX-containing PSPhy (ANX-PSPhy) cubosomes retain the Pn3m cubic symmetry and cubic phase nanoparticle characteristics of PSPhy cubosomes. The interaction of ANX-PSPhy cubosomes with apoptotic model and cellular membranes was also investigated using both quartz crystal microbalance with dissipation and confocal microscopy which confirmed that ANX-PSPhy cubosomes can selectively bind to apoptotic cells and model membranes. Neutron reflectometry has also been used to show strong binding of ANX-PSPhy cubosomes to a model apoptotic membrane, and in addition reveals changes in both the bilayer structure and in the internal structure of the cubosome in a region adjacent to the membrane as a result of material exchange. This material exchange between cubosome and apoptotic model bilayer was further demonstrated using Cryo-TEM. We have demonstrated that lipid bound protein, in this case Annexin V, can be used to target cubosome systems to biological surfaces in vitro. PMID:23899446

  16. Novel function of stabilin-2 in myoblast fusion: the recognition of extracellular phosphatidylserine as a "fuse-me" signal.

    PubMed

    Kim, Go-Woon; Park, Seung-Yoon; Kim, In-San

    2016-06-01

    Myoblast fusion is important for skeletal muscle formation. Even though the knowledge of myoblast fusion mechanism has accumulated over the years, the initial signal of fusion is yet to be elucidated. Our study reveals the novel function of a phosphatidylserine (PS) receptor, stabilin-2 (Stab2), in the modulation of myoblast fusion, through the recognition of PS exposed on myoblasts. During differentiation of myoblasts, Stab2 expression is higher than other PS receptors and is controlled by calcineurin/NFAT signaling on myoblasts. The forced expression of Stab2 results in an increase in myoblast fusion; genetic ablation of Stab2 in mice causes a reduction in muscle size, as a result of impaired myoblast fusion. After muscle injury, muscle regeneration is impaired in Stab2- deficient mice, resulting in small myofibers with fewer nuclei, which is due to reduction of fusion rather than defection of myoblast differentiation. The fusion-promoting role of Stab2 is dependent on its PS-binding motif, and the blocking of PS-Stab2 binding impairs cell-cell fusion on myoblasts. Given our previous finding that Stab2 recognizes PS exposed on apoptotic cells for sensing as an "eat-me" signal, we propose that PS-Stab2 binding is required for sensing of a "fuse-me" signal as the initial signal of myoblast fusion. [BMB Reports 2016; 49(6): 303-304].

  17. PI4P/phosphatidylserine countertransport at ORP5- and ORP8-mediated ER–plasma membrane contacts

    PubMed Central

    Chung, Jeeyun; Torta, Federico; Masai, Kaori; Lucast, Louise; Czapla, Heather; Tanner, Lukas B.; Narayanaswamy, Pradeep; Wenk, Markus R.

    2015-01-01

    Lipid transfer between cell membrane bilayers at contacts between the endoplasmic reticulum (ER) and other membranes help to maintain membrane lipid homeostasis. We found that two similar ER integral membrane proteins, oxysterol-binding protein (OSBP)–related protein 5 (ORP5) and ORP8, tethered the ER to the plasma membrane (PM) via the interaction of their pleckstrin homology domains with phosphatidylinositol 4-phosphate (PI4P) in this membrane. Their OSBP-related domains (ORDs) harbored either PI4P or phosphatidylserine (PS) and exchanged these lipids between bilayers. Gain- and loss-of-function experiments showed that ORP5 and ORP8 could mediate PI4P/PS counter transport between the ER and the PM, thus delivering PI4P to the ER-localized PI4P phosphatase Sac1 for degradation and PS from the ER to the PM. This exchange helps to control plasma membrane PI4P levels and selectively enrich PS in the PM. PMID:26206935

  18. p85α recruitment by the CD300f phosphatidylserine receptor mediates apoptotic cell clearance required for autoimmunity suppression

    PubMed Central

    Tian, Linjie; Choi, Seung-Chul; Murakami, Yousuke; Allen, Joselyn; Morse, Herbert C.; Qi, Chen-Feng; Krzewski, Konrad; Coligan, John E

    2014-01-01

    Apoptotic cell (AC) clearance is essential for immune homeostasis. Here we show that mouse CD300f (CLM-1) recognizes outer membrane-exposed phosphatidylserine, and regulates the phagocytosis of ACs. CD300f accumulates in phagocytic cups at AC contact sites. Phosphorylation within CD300f cytoplasmic tail tyrosine-based motifs initiates signals that positively or negatively regulate AC phagocytosis. Y276 phosphorylation is necessary for enhanced CD300f-mediated phagocytosis through the recruitment of the p85α regulatory subunit of phosphatidylinositol-3-kinase (PI3K). CD300f-PI3K association leads to activation of downstream Rac/Cdc42 GTPase and mediates changes of F-actin that drive AC engulfment. Importantly, primary macrophages from CD300f-deficient mice have impaired phagocytosis of ACs. The biological consequence of CD300f deficiency is predisposition to autoimmune disease development, as FcγRIIB-deficient mice develop a systemic lupus erythematosus-like disease at a markedly accelerated rate if CD300f is absent. In this report we identify the mechanism and role of CD300f in AC phagocytosis and maintenance of immune homeostasis. PMID:24477292

  19. p85α recruitment by the CD300f phosphatidylserine receptor mediates apoptotic cell clearance required for autoimmunity suppression

    NASA Astrophysics Data System (ADS)

    Tian, Linjie; Choi, Seung-Chul; Murakami, Yousuke; Allen, Joselyn; Morse, Herbert C., III; Qi, Chen-Feng; Krzewski, Konrad; Coligan, John E.

    2014-01-01

    Apoptotic cell (AC) clearance is essential for immune homeostasis. Here we show that mouse CD300f (CLM-1) recognizes outer membrane-exposed phosphatidylserine, and regulates the phagocytosis of ACs. CD300f accumulates in phagocytic cups at AC contact sites. Phosphorylation within CD300f cytoplasmic tail tyrosine-based motifs initiates signals that positively or negatively regulate AC phagocytosis. Y276 phosphorylation is necessary for enhanced CD300f-mediated phagocytosis through the recruitment of the p85α regulatory subunit of phosphatidylinositol-3-kinase (PI3K). CD300f-PI3K association leads to activation of downstream Rac/Cdc42 GTPase and mediates changes of F-actin that drive AC engulfment. Importantly, primary macrophages from CD300f-deficient mice have impaired phagocytosis of ACs. The biological consequence of CD300f deficiency is predisposition to autoimmune disease development, as FcγRIIB-deficient mice develop a systemic lupus erythematosus-like disease at a markedly accelerated rate if CD300f is absent. In this report we identify the mechanism and role of CD300f in AC phagocytosis and maintenance of immune homeostasis.

  20. Role of the lysine-rich cluster of the C2 domain in the phosphatidylserine-dependent activation of PKCalpha.

    PubMed

    Rodríguez-Alfaro, Jose A; Gomez-Fernandez, Juan C; Corbalan-Garcia, Senena

    2004-01-23

    The C2 domain of PKCalpha is a Ca(2+)-dependent membrane-targeting module involved in the plasma membrane localization of the enzyme. Recent findings have shown an additional area located in the beta3-beta4 strands, named the lysine-rich cluster, which has been demonstrated to be involved in the PtdIns(4,5)P(2)-dependent activation of the enzyme. Nevertheless, whether other anionic phospholipids can bind to this region and contribute to the regulation of the enzyme's function is not clear. To study other possible roles for this cluster, we generated double and triple mutants that substituted the lysine by alanine residues, and studied their binding and activation properties in a Ca(2+)/phosphatidylserine-dependent manner and compared them with the wild-type protein. It was found that some of the mutants exerted a constitutive activation independently of membrane binding. Furthermore, the constructs were fused to green fluorescent protein and were expressed in fibroblast cells. It was shown that none of the mutants was able to translocate to the plasma membrane, even in saturating conditions of Ca(2+) and diacylglycerol, suggesting that the interactions performed by this lysine-rich cluster are a key event in the subcellular localization of PKCalpha. Taken together, the results obtained showed that these lysine residues might be involved in two functions: one to establish an intramolecular interaction that keeps the enzyme in an inactive conformation; and the second, once the enzyme has been partially activated, to establish further interactions with diacylglycerol and/or acidic phospholipids, leading to the full activation of PKCalpha.

  1. Taxol induces concentration-dependent phosphatidylserine (PS) externalization and cell cycle arrest in ASTC-a-1 cells

    NASA Astrophysics Data System (ADS)

    Guo, Wen-jing; Chen, Tong-sheng

    2010-02-01

    Taxol (Paclitaxel) is an important natural product for the treatment of solid tumors. Different concentrations of taxol can trigger distinct effects on both the cellular microtubule network and biochemical pathways. Apoptosis induced by low concentrations (5-30 nM) of taxol was associated with mitotic arrest, alteration of microtubule dynamics and/or G2/M cell cycle arrest, whereas high concentrations of this drug (0.2-30 μM) caused significant microtubule damage, and was found recently to induce cytoplasm vacuolization in human lung adenocarcinoma (ASTC-a-1) cells. In present study, cell counting kit (CCK-8) assay, confocal microscope, and flow cytometry analysis were used to analyze the cell death form induced by 35 nM and 70 μM of taxol respectively in human lung adenocarcinoma (ASTC-a-1) cells. After treatment of 35 nM taxol for 48 h, the OD450 value was 0.80, and 35 nM taxol was found to induce dominantly cell death in apoptotic pathway such as phosphatidylserine (PS) externalization, G2/M phase arrest after treatment for 24 h, and nuclear fragmentation after treatment for 48 h. After 70 μM taxol treated the cell for 24 h, the OD450 value was 1.01, and 70 μM taxol induced cytoplasm vacuolization programmed cell death (PCD) and G2/M phase as well as the polyploidy phase arrest in paraptotic-like cell death. These findings imply that the regulated signaling pathway of cell death induced by taxol is dependent on taxol concentration in ASTC-a-1 cells.

  2. Calpain-controlled detachment of major glycoproteins from the cytoskeleton regulates adhesive properties of activated phosphatidylserine-positive platelets.

    PubMed

    Artemenko, Elena O; Yakimenko, Alena O; Pichugin, Alexey V; Ataullakhanov, Fazly I; Panteleev, Mikhail A

    2016-02-15

    In resting platelets, adhesive membrane glycoproteins are attached to the cytoskeleton. On strong activation, phosphatidylserine(PS)-positive and -negative platelet subpopulations are formed. Platelet activation is accompanied by cytoskeletal rearrangement, although the glycoprotein attachment status in these two subpopulations is not clear. We developed a new, flow cytometry-based, single-cell approach to investigate attachment of membrane glycoproteins to the cytoskeleton in cell subpopulations. In PS-negative platelets, adhesive glycoproteins integrin αIIbβ3, glycoprotein Ib and, as shown for the first time, P-selectin were associated with the cytoskeleton. In contrast, this attachment was disrupted in PS-positive platelets; it was retained to some extent only in the small convex regions or 'caps'. It correlated with the degradation of talin and filamin observed only in PS-positive platelets. Calpain inhibitors essentially prevented the disruption of membrane glycoprotein attachment in PS-positive platelets, as well as talin and filamin degradation. With the suggestion that detachment of glycoproteins from the cytoskeleton may affect platelet adhesive properties, we investigated the ability of PS-positive platelets to resist shear-induced breakaway from the immobilized fibrinogen. Shear rates of 500/s caused PS-positive platelet breakaway, but their adhesion stability increased more than 10-fold after pretreatment of the platelets with calpain inhibitor. In contrast, the ability of PS-positive platelets to adhere to immobilized von Willebrand's factor at 100/s was low, but this was not affected by the preincubation of platelets with a calpain inhibitor. Our data suggest that calpain-controlled detachment of membrane glycoproteins is a new mechanism that is responsible for the loss of ability of the procoagulant platelets to resist detachment from thrombi by high shear stress.

  3. The intrinsic pKa values for phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine in monolayers deposited on mercury electrodes.

    PubMed Central

    Moncelli, M R; Becucci, L; Guidelli, R

    1994-01-01

    The intrinsic pKa values of the phosphate groups of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) and of the phosphate and carboxyl groups of phosphatidylserine (PS) in self-organized monolayers deposited on a hanging mercury drop electrode were determined by a novel procedure based on measurements of the differential capacity C of this lipid-coated electrode. In view of the Gouy-Chapman theory, plots of 1/C at constant bulk pH and variable KCl concentration against the reciprocal of the calculated diffuse-layer capacity Cd,0 at zero charge exhibit slopes that decrease from an almost unit value to vanishingly low values as the absolute value of the charge density on the lipid increases from zero to approximately 2 microC cm-2. The intrinsic pKa values so determined are 0.5 for PE and 0.8 for PC. The plots of 1/C against 1/Cd,0 for pure PS exhibit slopes that pass from zero to a maximum value and then back to zero as pH is varied from 7.5 to 3, indicating that the charge density of the lipid film passes from slight negative to slight positive values over this pH range. An explanation for this anomalous behavior, which is ascribed to the phosphate group of PS, is provided. Interdispersion of PS and PC molecules in the film decreases the "formal" pKa value of the latter group by about three orders of magnitude. PMID:8075331

  4. T Cell/Transmembrane, Ig, and Mucin-3 Allelic Variants Differentially Recognize Phosphatidylserine and Mediate Phagocytosis of Apoptotic Cells

    PubMed Central

    DeKruyff, Rosemarie H.; Bu, Xia; Ballesteros, Angela; Santiago, César; Chim, Yee-Ling E.; Lee, Hyun-Hee; Karisola, Piia; Pichavant, Muriel; Kaplan, Gerardo G.; Umetsu, Dale T.; Freeman, Gordon J.; Casasnovas, José M.

    2011-01-01

    T cell/transmembrane, Ig, and mucin (TIM) proteins, identified using a congenic mouse model of asthma, critically regulate innate and adaptive immunity. TIM-1 and TIM-4 are receptors for phosphatidylserine (PtdSer), exposed on the surfaces of apoptotic cells. Herein, we show with structural and biological studies that TIM-3 is also a receptor for PtdSer that binds in a pocket on the N-terminal IgV domain in coordination with a calcium ion. The TIM-3/PtdSer structure is similar to that of TIM-4/PtdSer, reflecting a conserved PtdSer binding mode by TIM family members. Fibroblastic cells expressing mouse or human TIM-3 bound and phagocytosed apoptotic cells, with the BALB/c allelic variant of mouse TIM-3 showing a higher capacity than the congenic C.D2 Es-Hba–allelic variant. These functional differences were due to structural differences in the BC loop of the IgV domain of the TIM-3 polymorphic variants. In contrast to fibroblastic cells, T or B cells expressing TIM-3 formed conjugates with but failed to engulf apoptotic cells. Together these findings indicate that TIM-3–expressing cells can respond to apoptotic cells, but the consequence of TIM-3 engagement of PtdSer depends on the polymorphic variants of and type of cell expressing TIM-3. These findings establish a new paradigm for TIM proteins as PtdSer receptors and unify the function of the TIM gene family, which has been associated with asthma and autoimmunity and shown to modulate peripheral tolerance. PMID:20083673

  5. Mutational analysis of Raf-1 cysteine rich domain: requirement for a cluster of basic aminoacids for interaction with phosphatidylserine.

    PubMed

    Improta-Brears, T; Ghosh, S; Bell, R M

    1999-08-01

    Activation of Raf-1 kinase is preceded by a translocation of Raf-1 to the plasma membrane in response to external stimuli. The membrane localization of Raf-1 is facilitated through its interaction with activated Ras and with membrane phospholipids. Previous evidence suggests that the interaction of Raf-1 with Ras is mediated by two distinct domains within the N-terminal region of Raf-1 comprising amino acid residues 51-131 and residues 139-184, the latter of which codes for a zinc containing cysteine-rich domain. The cysteine-rich domain of Raf-1 is also reported to associate with other proteins, such as 14-3-3, and for selectively binding acidic phospholipids, particularly phosphatidylserine (PS). In the present study, we have investigated the consequences of progressive deletions and point mutations within the cysteine-rich domain of Raf-1 on its ability to bind PS. A reduced interaction with PS was observed in vitro for all deletion mutants of Raf-1 expressed either as full-length proteins or as fragments containing the isolated cysteine-rich domain. In particular, the cluster of basic amino acids R143, K144, and K148 appeared to be critical for interaction with PS, since substitution of all three residues to alanine resulted in a protein that failed to interact with liposomes enriched for PS. Expression of Raf-1 in vivo, containing point mutations in the cysteine-rich domain resulted in a truncated polypeptide that lacked both the Ras and PS binding sites and could no longer translocate to the plasma membrane upon serum stimulation. These results indicate that the basic residues 143, 144 and 148 in the anterior half of Raf-1 cysteine-rich domain play a role in the association with the lipid bilayer and possibly in protein stability, therefore they might contribute to Raf-1 localization and subsequent activation.

  6. Reversible Photoswitching of Carbon Dots

    PubMed Central

    Khan, Syamantak; Verma, Navneet Chandra; Gupta, Abhishek; Nandi, Chayan Kanti

    2015-01-01

    We present a method of reversible photoswitching in carbon nanodots with red emission. A mechanism of electron transfer is proposed. The cationic dark state, formed by the exposure of red light, is revived back to the bright state with the very short exposure of blue light. Additionally, the natural on-off state of carbon dot fluorescence was tuned using an electron acceptor molecule. Our observation can make the carbon dots as an excellent candidate for the super-resolution imaging of nanoscale biomolecules within the cell. PMID:26078266

  7. Effect of Phosphatidylserine on Unitary Conductance and Ba2+ Block of the BK Ca2+–activated K+ Channel

    PubMed Central

    Park, Jin Bong; Kim, Hee Jeong; Ryu, Pan Dong; Moczydlowski, Edward

    2003-01-01

    Incorporation of BK Ca2+–activated K+ channels into planar bilayers composed of negatively charged phospholipids such as phosphatidylserine (PS) or phosphatidylinositol (PI) results in a large enhancement of unitary conductance (gch) in comparison to BK channels in bilayers formed from the neutral zwitterionic lipid, phospatidylethanolamine (PE). Enhancement of gch by PS or PI is inversely dependent on KCl concentration, decreasing from 70% at 10 mM KCl to 8% at 1,000 mM KCl. This effect was explained previously by a surface charge hypothesis (Moczydlowski, E., O. Alvarez, C. Vergara, and R. Latorre. 1985. J. Membr. Biol. 83:273–282), which attributed the conductance enhancement to an increase in local K+ concentration near the entryways of the channel. To test this hypothesis, we measured the kinetics of block by external and internal Ba2+, a divalent cation that is expected to respond strongly to changes in surface electrostatics. We observed little or no effect of PS on discrete blocking kinetics by external and internal Ba2+ at 100 mM KCl and only a small enhancement of discrete and fast block by external Ba2+ in PS-containing membranes at 20 mM KCl. Model calculations of effective surface potential sensed by the K+ conduction and Ba2+-blocking reactions using the Gouy-Chapman-Stern theory of lipid surface charge do not lend support to a simple electrostatic mechanism that predicts valence-dependent increase of local cation concentration. The results imply that the conduction pore of the BK channel is electrostatically insulated from the lipid surface, presumably by a lateral distance of separation (>20 Å) from the lipid head groups. The lack of effect of PS on apparent association and dissociation rates of Ba2+ suggest that lipid modulation of K+ conductance is preferentially coupled through conformational changes of the selectivity filter region that determine the high K+ flux rate of this channel relative to other cations. We discuss possible mechanisms

  8. Reversible surface aggregation in pore formation by pardaxin.

    PubMed Central

    Rapaport, D; Peled, R; Nir, S; Shai, Y

    1996-01-01

    The mechanism of leakage induced by surface active peptides is not yet fully understood. To gain insight into the molecular events underlying this process, the leakage induced by the peptide pardaxin from phosphatidylcholine/ phosphatidylserine/cholesterol large unilamellar vesicles was studied by monitoring the rate and extent of dye release and by theoretical modeling. The leakage occurred by an all-or-none mechanism: vesicles either leaked or retained all of their contents. We further developed a mathematical model that includes the assumption that certain peptides become incorporated into the vesicle bilayer and aggregate to form a pore. The current experimental results can be explained by the model only if the surface aggregation of the peptide is reversible. Considering this reversibility, the model can explain the final extents of calcein leakage for lipid/peptide ratios of > 2000:1 to 25:1 by assuming that only a fraction of the bound peptide forms pores consisting of M = 6 +/- 3 peptides. Interestingly, less leakage occurred at 43 degrees C, than at 30 degrees C, although peptide partitioning into the bilayer was enhanced upon elevation of the temperature. We deduced that the increased leakage at 30 degrees C was due to an increase in the extent of reversible surface aggregation at the lower temperature. Experiments employing fluorescein-labeled pardaxin demonstrated reversible aggregation of the peptide in suspension and within the membrane, and exchange of the peptide between liposomes. In summary, our experimental and theoretical results support reversible surface aggregation as the mechanism of pore formation by pardaxin. Images FIGURE 7 PMID:8744290

  9. Reversible Thermoset Adhesives

    NASA Technical Reports Server (NTRS)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  10. Removal of spermatozoa with externalized phosphatidylserine from sperm preparation in human assisted medical procreation: effects on viability, motility and mitochondrial membrane potential

    PubMed Central

    de Vantéry Arrighi, Corinne; Lucas, Hervé; Chardonnens, Didier; de Agostini, Ariane

    2009-01-01

    Background Externalization of phosphatidylserine (EPS) occurs in apoptotic-like spermatozoa and could be used to remove them from sperm preparations to enhance sperm quality for assisted medical procreation. We first characterized EPS in sperms from infertile patients in terms of frequency of EPS spermatozoa as well as localization of phosphatidylserine (PS) on spermatozoa. Subsequently, we determined the impact of depleting EPS spermatozoa on sperm quality. Methods EPS were visualized by fluorescently-labeled annexin V binding assay. Double staining with annexin V and Hoechst differentiates apoptotic from necrotic spermatozoa. We used magnetic-activated cell sorting using annexin V-conjugated microbeads (MACS-ANMB) technique to remove EPS spermatozoa from sperm prepared by density gradient centrifugation (DGC). The impact of this technique on sperm quality was evaluated by measuring progressive motility, viability, and the integrity of the mitochondrial membrane potential (MMP) by Rhodamine 123. Results Mean percentages of EPS spermatozoa were 14% in DGC sperm. Four subpopulations of spermatozoa were identified: 70% alive, 3% early apoptotic, 16% necrotic and 11% late apoptotic or necrotic. PS were localized on head and/or midpiece or on the whole spermatozoa. MACS efficiently eliminates EPS spermatozoa. MACS combined with DGC allows a mean reduction of 70% in EPS and of 60% in MMP-disrupted spermatozoa with a mean increase of 50% in sperm survival at 24 h. Conclusion Human ejaculates contain EPS spermatozoa which can mostly be eliminated by DGC plus MACS resulting in improved sperm long term viability, motility and MMP integrity. EPS may be used as an indicator of sperm quality and removal of EPS spermatozoa may enhance fertility potential in assisted medical procreation. PMID:19133142

  11. Associations of B- and C-Raf with cholesterol, phosphatidylserine, and lipid second messengers: preferential binding of Raf to artificial lipid rafts.

    PubMed

    Hekman, Mirko; Hamm, Heike; Villar, Ana V; Bader, Benjamin; Kuhlmann, Jurgen; Nickel, Joachim; Rapp, Ulf R

    2002-07-01

    The serine/threonine kinase C-Raf is a key mediator in cellular signaling. Translocation of Raf to membranes has been proposed to be facilitated by Ras proteins in their GTP-bound state. In this study we provide evidence that both purified B- and C-Raf kinases possess lipophilic properties and associate with phospholipid membranes. In the presence of phosphatidylserine and lipid second messengers such as phosphatidic acid and ceramides these associations were very specific with affinity constants (K(D)) in the range of 0.5-50 nm. Raf association with liposomes was accompanied by displacement of 14-3-3 proteins and inhibition of Raf kinase activities. Interactions of Raf with cholesterol are of particular interest, since cholesterol has been shown to be involved, together with sphingomyelin and glycerophospholipids in the formation of specialized lipid microdomains called rafts. We demonstrate here that purified Raf proteins have moderate binding affinity for cholesterol. However, under conditions of lipid raft formation, Raf association with cholesterol (or rafts) increased dramatically. Since ceramides also support formation of rafts and interact with Raf we propose that Raf may be present at the plasma membrane in two distinct microdomains: in raft regions via association with cholesterol and ceramides and in non-raft regions due to interaction with phosphatidylserine and phosphatidic acid. At either location Raf kinase activity was inhibited by lipid binding in the absence or presence of Ras. Ras-Raf interactions with full-length C-Raf were studied both in solution and in phospholipid environment. Ras association with Raf was GTP dependent as previously demonstrated for C-Raf-RBD fragments. In the presence of liposomes the recruitment of C-Raf by reconstituted Ras-farnesyl was only marginal, since almost 70% of added C-Raf was bound by the lipids alone. Thus Ras-Raf binding in response to activation of Ras-coupled receptors may utilize Raf protein that is

  12. Quantum Operation Time Reversal

    SciTech Connect

    Crooks, Gavin E.

    2008-03-25

    The dynamics of an open quantum system can be described by a quantum operation: A linear, complete positive map of operators. Here, I exhibit a compact expression for the time reversal of a quantum operation, which is closely analogous to the time reversal of a classical Markov transition matrix. Since open quantum dynamics are stochastic, and not, in general, deterministic, the time reversal is not, in general, an inversion of the dynamics. Rather, the system relaxes toward equilibrium in both the forward and reverse time directions. The probability of a quantum trajectory and the conjugate, time reversed trajectory are related by the heat exchanged with the environment.

  13. The Grammar of Action and Reversal Errors in Children's Printing.

    ERIC Educational Resources Information Center

    Simner, Marvin L.

    1984-01-01

    Studies predictions about letter reversals made by Goodnow's "grammar of action." Two samples of right- and left-handed children in nursery school through first grade printed from memory immediately after exposure to each of 41 reversible letters and numbers. Results challenge "grammar of action" proposals about the inappropriate applications of…

  14. Vasectomy reversal in humans.

    PubMed

    Bernie, Aaron M; Osterberg, E Charles; Stahl, Peter J; Ramasamy, Ranjith; Goldstein, Marc

    2012-10-01

    Vasectomy is the most common urological procedure in the United States with 18% of men having a vasectomy before age 45. A significant proportion of vasectomized men ultimately request vasectomy reversal, usually due to divorce and/or remarriage. Vasectomy reversal is a commonly practiced but technically demanding microsurgical procedure that restores patency of the male excurrent ductal system in 80-99.5% of cases and enables unassisted pregnancy in 40-80% of couples. The discrepancy between the anastomotic patency rates and clinical pregnancy rates following vasectomy reversal suggests that some of the biological consequences of vasectomy may not be entirely reversible in all men. Herein we review what is known about the biological sequelae of vasectomy and vasectomy reversal in humans, and provide a succinct overview of the evaluation and surgical management of men desiring vasectomy reversal.

  15. Justice and Reverse Discrimination.

    ERIC Educational Resources Information Center

    Goldman, Alan H.

    Defining reverse discrimination as hiring or admissions decisions based on normally irrelevant criteria, this book develops principles of rights, compensation, and equal opportunity applicable to the reverse discrimination issue. The introduction defines the issue and discusses deductive and inductive methodology as applied to reverse…

  16. Quantum reverse hypercontractivity

    SciTech Connect

    Cubitt, Toby; Kastoryano, Michael; Montanaro, Ashley; Temme, Kristan

    2015-10-15

    We develop reverse versions of hypercontractive inequalities for quantum channels. By generalizing classical techniques, we prove a reverse hypercontractive inequality for tensor products of qubit depolarizing channels. We apply this to obtain a rapid mixing result for depolarizing noise applied to large subspaces and to prove bounds on a quantum generalization of non-interactive correlation distillation.

  17. Reverse Discrimination: Recent Cases.

    ERIC Educational Resources Information Center

    Steinhilber, August W.

    This paper discusses reverse discrimination cases with particular emphasis on Bakke v. Regents of University of California and those cases which preceded it. A brief history is given of court cases used by opponents and proponents in the discussion of reverse discrimination. Legal theory and a discussion of court cases that preceded Bakke follow.…

  18. Monitoring apoptosis and neuronal degeneration by real-time detection of phosphatidylserine externalization using a polarity-sensitive indicator of viability and apoptosis

    PubMed Central

    Kim, Yujin E; Chen, Jeannie; Langen, Ralf; Chan, Jonah R

    2015-01-01

    Applications for noninvasive real-time imaging of apoptosis and neuronal degeneration are hindered by technical limitations in imaging strategies and by existing probes. Monitoring the progression of a cell through apoptosis could provide valuable insight into the temporal events that initiate cell death as well as the potential for rescue of apoptotic cells. We engineered an annexin-based biosensor to function as a polarity-sensitive indicator for viability and apoptosis (known as psIVa) by binding to externalized phosphatidylserine (ps) exposed on apoptotic cell membranes. constructed from a structure-based design strategy, psIVa fluoresces only when bound to ps and remains effectively undetectable in solution. In this paper, we describe protocols for the design, expression, purification and labeling of psIVa as well as for its application in time-lapse imaging of degenerating neurons in culture; the entire protocol can be completed in 2 weeks. the primary advantage of this method is the flexibility to use psIVa, in combination with other probes and without perturbing experimental conditions, to explore the cellular mechanisms involved in apoptosis and degeneration in real time. PMID:20671723

  19. Mechanism of Action of Thymosinα1: Does It Interact with Membrane by Recognition of Exposed Phosphatidylserine on Cell Surface? A Structural Approach.

    PubMed

    Nepravishta, R; Mandaliti, W; Vallebona, P S; Pica, F; Garaci, E; Paci, M

    2016-01-01

    Thymosinα1 is a peptidic hormone with pleiotropic activity, which is used in the therapy of several diseases. It is unstructured in water solution and interacts with negative regions of micelles and vesicles assuming two tracts of helical conformation with a structural flexible break in between. The studies of the interaction of Thymosinα1 with micelles of mixed dipalmitoylphosphatidylcholine and sodium dodecylsulfate and vesicles with mixed dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylserine, the latter the negative component of the membranes, by (1)H and natural abundance (15)N NMR are herewith reported, reviewed, and discussed. The results indicate that the preferred interactions are those where the surface is negatively charged due to sodium dodecylsulfate or due to the presence of dipalmitoylphosphatidylserine exposed on the surface. In fact the unbalance of dipalmitoylphosphatidylserine on the cellular surface is an important phenomenon present in pathological conditions of cells. Moreover, the direct interaction of Thymosinα1 with K562 cells presenting an overexposure of phosphatidylserine as a consequence of resveratrol-induced apoptosis was carried out. PMID:27450732

  20. Cationic gradient reversal and cytoskeleton-independent volume regulatory pathways define an early stage of apoptosis.

    PubMed

    Bortner, Carl D; Sifre, Maria I; Cidlowski, John A

    2008-03-14

    Cell shrinkage, or apoptotic volume decrease (AVD), is a ubiquitous characteristic of programmed cell death that is independent of the death stimulus and occurs in all examples of apoptosis. Here we distinguished two specific stages of AVD based on cell size and a unique early reversal of intracellular ions that occurs in response to activation of both intrinsic and extrinsic cell death signal pathways. The primary stage of AVD is characterized by an early exchange of the normal intracellular ion distribution for sodium from 12 to 113.6 mm and potassium from 139.5 to 30 mm. This early ionic reversal is associated with a 20-40% decrease in cell volume, externalization of phosphatidylserine, loss of mitochondrial membrane potential, and caspase activation and activity along with nuclear condensation that occurs independent of actin cytoskeleton disruption. Disruption of the actin cytoskeleton, however, prevents a secondary stage of AVD in apoptotic cells, characterized by a loss of both potassium and sodium that results in an 80-85% loss in cell volume, DNA degradation, and apoptotic body formation. Together these studies demonstrate that AVD occurs in two distinct stages with the earliest stage reflecting a cellular cationic gradient reversal.

  1. TELOMERASE AND CHRONIC ARSENIC EXPOSURE IN HUMANS

    EPA Science Inventory

    Arsenic exposure has been associated with increased risk of skin, lung and bladder cancer in humans. The mechanisms of carcinogenesis are not well understood. Telomerase, a ribonucleoprotein containing human telomerase reverse transcriptase (hTERT), can extend telomeres of eukary...

  2. Reversible optical doping of graphene

    PubMed Central

    Tiberj, A.; Rubio-Roy, M.; Paillet, M.; Huntzinger, J. -R.; Landois, P.; Mikolasek, M.; Contreras, S.; Sauvajol, J. -L.; Dujardin, E.; Zahab, A. -A.

    2013-01-01

    The ultimate surface exposure provided by graphene monolayer makes it the ideal sensor platform but also exposes its intrinsic properties to any environmental perturbations. In this work, we demonstrate that the charge carrier density of graphene exfoliated on a SiO2/Si substrate can be finely and reversibly tuned between hole and electron doping with visible photons. This photo-induced doping happens under moderate laser power conditions but is significantly affected by the substrate cleaning method. In particular, it requires hydrophilic substrates and vanishes for suspended graphene. These findings suggest that optically gated graphene devices operating with a sub-second time scale can be envisioned and that Raman spectroscopy is not always as non-invasive as generally assumed. PMID:23912707

  3. Reversing the arms race

    SciTech Connect

    von Hippel, F. ); Sagdeev, R.Z. )

    1992-01-01

    This paper contains proceedings of Reversing The Arms Race. Topics covered include: Verifying Reductions of Nuclear Warheads; Verifying Limits on Nuclear-Armed Cruise Missiles; and The Technical Basis for Warhead Detection.

  4. Interaction of phosphatidic acid and phosphatidylserine with the Ca2+-ATPase of sarcoplasmic reticulum and the mechanism of inhibition.

    PubMed

    Dalton, K A; East, J M; Mall, S; Oliver, S; Starling, A P; Lee, A G

    1998-02-01

    The sarcoplasmic reticulum of skeletal muscle contains anionic phospholipids as well as the zwitterionic phosphatidylcholine and phosphatidylethanolamine. Here we study the effects of anionic phospholipids on the activity of the Ca2+-ATPase purified from the membrane. Reconstitution of the Ca2+-ATPase into dioleoylphosphatidylserine [di(C18:1)PS] or dioleoylphosphatidic acid [di(C18:1)PA] leads to a decrease in ATPase activity. Measurements of the quenching of the tryptophan fluorescence of the ATPase by brominated phospholipids give a relative binding constant for the anionic lipids compared with dioleoylphosphatidylcholine close to 1 and suggest that phosphatidic acid only binds to the ATPase at the bulk lipid sites around the ATPase. Addition of di(C18:1)PS or di(C18:1)PA to the ATPase in the short-chain dimyristoleoylphosphatidylcholine [di(C14:1)PC] reverse the effects of the short-chain lipid on ATPase activity and on Ca2+ binding, as revealed by the response of tryptophan fluorescence intensity to Ca2+ binding. It is concluded that the lipid headgroup and lipid fatty acyl chains have separate effects on the function of the ATPase. The anionic phospholipids have no significant effect on Ca2+ binding to the ATPase; the level of Ca2+ binding to the ATPase, the affinity of binding and the rate of dissociation of Ca2+ are unchanged by reconstitution into di(C18:1)PA. The major effect of the anionic lipids is a reduction in the maximal level of binding of MgATP. This is attributed to the formation of oligomers of the Ca2+-ATPase, in which only one molecule of the ATPase can bind MgATP dimers in di(C18:1)PS and trimers or tetramers in di(C18:1)PA. The rates of phosphorylation and dephosphorylation for the proportion of the ATPase still able to bind ATP are unaffected by reconstitution. Larger changes were observed in the level of phosphorylation of the ATPase by Pi, which became very low in the anionic phospholipids. The fluorescence response to Mg2+ for the ATPase

  5. Particle exposures and infections.

    PubMed

    Ghio, A J

    2014-06-01

    Particle exposures increase the risk for human infections. Particles can deposit in the nose, pharynx, larynx, trachea, bronchi, and distal lung and, accordingly, the respiratory tract is the system most frequently infected after such exposure; however, meningitis also occurs. Cigarette smoking, burning of biomass, dust storms, mining, agricultural work, environmental tobacco smoke (ETS), wood stoves, traffic-related emissions, gas stoves, and ambient air pollution are all particle-related exposures associated with an increased risk for respiratory infections. In addition, cigarette smoking, burning of biomass, dust storms, mining, and ETS can result in an elevated risk for tuberculosis, atypical mycobacterial infections, and meningitis. One of the mechanisms for particle-related infections includes an accumulation of iron by surface functional groups of particulate matter (PM). Since elevations in metal availability are common to every particle exposure, all PM potentially contributes to these infections. Therefore, exposures to wood stove emissions, diesel exhaust, and air pollution particles are predicted to increase the incidence and prevalence of tuberculosis, atypical mycobacterial infections, and meningitis, albeit these elevations are likely to be small and detectable only in large population studies. Since iron accumulation correlates with the presence of surface functional groups and dependent metal coordination by the PM, the risk for infection continues as long as the particle is retained. Subsequently, it is expected that the cessation of exposure will diminish, but not totally reverse, the elevated risk for infection.

  6. Reversibility of antibiotic resistance

    PubMed Central

    2014-01-01

    Although theoretically attractive, the reversibility of resistance has proven difficult in practice, even though antibiotic resistance mechanisms induce a fitness cost to the bacterium. Associated resistance to other antibiotics and compensatory mutations seem to ameliorate the effect of antibiotic interventions in the community. In this paper the current understanding of the concepts of reversibility of antibiotic resistance and the interventions performed in hospitals and in the community are reviewed. PMID:24836051

  7. Adaptive Pairing Reversible Watermarking.

    PubMed

    Dragoi, Ioan-Catalin; Coltuc, Dinu

    2016-05-01

    This letter revisits the pairwise reversible watermarking scheme of Ou et al., 2013. An adaptive pixel pairing that considers only pixels with similar prediction errors is introduced. This adaptive approach provides an increased number of pixel pairs where both pixels are embedded and decreases the number of shifted pixels. The adaptive pairwise reversible watermarking outperforms the state-of-the-art low embedding bit-rate schemes proposed so far.

  8. Chronic exposure to tumor necrosis factor (TNF) in vitro impairs the activation of T cells through the T cell receptor/CD3 complex; reversal in vivo by anti-TNF antibodies in patients with rheumatoid arthritis.

    PubMed Central

    Cope, A P; Londei, M; Chu, N R; Cohen, S B; Elliott, M J; Brennan, F M; Maini, R N; Feldmann, M

    1994-01-01

    Experiments were designed to test the hypothesis that chronic exposure to tumor necrosis factor alpha (TNF) alters the function of activated T lymphocytes. Pretreatment of tetanus toxoid-specific T cell clones with TNF for up to 16 d impaired rechallenge proliferative responses to antigen in a dose- and time-dependent fashion. IL-2 and PHA responses were preserved. Prolonged treatment with TNF impaired production of IL-2, IL-10, IFN gamma, TNF, and lymphotoxin (LT) following stimulation with immobilized OKT3, and resulted in suboptimal expression of the IL-2R alpha chain (Tac) but not CD3, CD4, or HLA-DR antigens, when compared to untreated control cells. By contrast, pretreatment of T cells for prolonged periods in vitro with neutralizing anti-TNF monoclonal antibodies (mAb) enhanced proliferative responses, increased lymphokine production, and upregulated Tac expression following stimulation with OKT3. To determine whether TNF exerts immunosuppressive effects on T cells in vivo, we studied cell-mediated immunity in patients with active rheumatoid arthritis (RA), before and after treatment with a chimeric anti-TNF mAb. Treatment with anti-TNF restored the diminished proliferative responses of PBMC to mitogens and recall antigens towards normal in all patients tested. These data demonstrate that persistent expression of TNF in vitro and in vivo impairs cell-mediated immune responses. Images PMID:8040330

  9. On thermodynamic and microscopic reversibility

    SciTech Connect

    Crooks, Gavin E.

    2011-07-12

    The word 'reversible' has two (apparently) distinct applications in statistical thermodynamics. A thermodynamically reversible process indicates an experimental protocol for which the entropy change is zero, whereas the principle of microscopic reversibility asserts that the probability of any trajectory of a system through phase space equals that of the time reversed trajectory. However, these two terms are actually synonymous: a thermodynamically reversible process is microscopically reversible, and vice versa.

  10. Diet-induced obesity resistance of adult female mice selectively bred for increased wheel-running behavior is reversed by single perinatal exposure to a high-energy diet.

    PubMed

    Guidotti, Stefano; Meyer, Neele; Przybyt, Ewa; Scheurink, Anton J W; Harmsen, Martin C; Garland, Theodore; van Dijk, Gertjan

    2016-04-01

    Female mice from independently bred lines previously selected over 50 generations for increased voluntary wheel-running behavior (S1, S2) resist high energy (HE) diet-induced obesity (DIO) at adulthood, even without actual access to running wheels, as opposed to randomly bred controls (CON). We investigated whether adult S mice without wheels remain DIO-resistant when exposed - via the mother - to the HE diet during their perinatal stage (from 2 weeks prior to conception until weaning on post-natal day 21). While S1 and S2 females subjected to HE diet either perinatally or from weaning onwards (post-weaning) resisted increased adiposity at adulthood (as opposed to CON females), they lost this resistance when challenged with HE diet during these periods combined over one single cycle of breeding. When allowed one-week access to wheels (at week 6-8 and at 10 months), however, tendency for increased wheel-running behavior of S mice was unaltered. Thus, the trait for increased wheel-running behavior remained intact following combined perinatal and post-weaning HE exposure, but apparently this did not block HE-induced weight gain. At weaning, perinatal HE diet increased adiposity in all lines, but this was only associated with hyperleptinemia in S lines irrespective of gender. Because leptin has multiple developmental effects at adolescence, we argue that a trait for increased physical activity may advance maturation in times of plenty. This would be adaptive in nature where episodes of increased nutrient availability should be exploited maximally. Associated disturbances in glucose homeostasis and related co-morbidities at adulthood are probably pleiotropic side effects.

  11. Diet-induced obesity resistance of adult female mice selectively bred for increased wheel-running behavior is reversed by single perinatal exposure to a high-energy diet.

    PubMed

    Guidotti, Stefano; Meyer, Neele; Przybyt, Ewa; Scheurink, Anton J W; Harmsen, Martin C; Garland, Theodore; van Dijk, Gertjan

    2016-04-01

    Female mice from independently bred lines previously selected over 50 generations for increased voluntary wheel-running behavior (S1, S2) resist high energy (HE) diet-induced obesity (DIO) at adulthood, even without actual access to running wheels, as opposed to randomly bred controls (CON). We investigated whether adult S mice without wheels remain DIO-resistant when exposed - via the mother - to the HE diet during their perinatal stage (from 2 weeks prior to conception until weaning on post-natal day 21). While S1 and S2 females subjected to HE diet either perinatally or from weaning onwards (post-weaning) resisted increased adiposity at adulthood (as opposed to CON females), they lost this resistance when challenged with HE diet during these periods combined over one single cycle of breeding. When allowed one-week access to wheels (at week 6-8 and at 10 months), however, tendency for increased wheel-running behavior of S mice was unaltered. Thus, the trait for increased wheel-running behavior remained intact following combined perinatal and post-weaning HE exposure, but apparently this did not block HE-induced weight gain. At weaning, perinatal HE diet increased adiposity in all lines, but this was only associated with hyperleptinemia in S lines irrespective of gender. Because leptin has multiple developmental effects at adolescence, we argue that a trait for increased physical activity may advance maturation in times of plenty. This would be adaptive in nature where episodes of increased nutrient availability should be exploited maximally. Associated disturbances in glucose homeostasis and related co-morbidities at adulthood are probably pleiotropic side effects. PMID:26850290

  12. Military Exposures

    MedlinePlus

    ... Index Agent Orange Agent Orange Home Facts about Herbicides Veterans' Diseases Birth Defects Benefits Exposure Locations Provider ... for Providers Diagnosis and Treatment of Exposure Health Effects More Provider Resources » return to top Get Email ...

  13. Prevalence of antibodies to prothrombin in solid phase (aPT) and to phosphatidylserine-prothrombin complex (aPS/PT) in patients with and without lupus anticoagulant.

    PubMed

    Bertolaccini, Maria Laura; Sciascia, Savino; Murru, Veronica; Garcia-Fernandez, Cesar; Sanna, Giovanni; Khamashta, Munther A

    2013-02-01

    Antibodies to prothrombin in solid phase (aPT) and those to phosphatidiyserine-prothrombin complex (aPS/PT) have been suggested to strongly correlate with the presence of lupus anticoagulant (LA). As their clinical diagnostic value and true relationship with the LA remains elusive, we designed this study to evaluate the prevalence and significance of aPT and aPS/PT in a large cohort of patients with and without LA. Samples from 257 patients were included. aPT and aPS/PT were tested by ELISA. LA was tested as per the current criteria from the ISTH Subcommittee on LA-Phospholipid-dependent antibodies. aPS/PT and aPT were found in 51% and 32% of LA-positive (LA+ve) patients and in 22% and 28% of LA-negative (LA-ve) patients, respectively. Thrombosis, particularly venous thrombosis was associated with IgG aPT in the LA+ve group (p=0.0006) and in the LA-ve group (p=0.017). Antibodies to phosphatidylserine-prothrombin, either IgG and IgM were associated with thrombosis in general (p=0.0003) in particularly with venous thrombosis in the LA+ve group (p<0.0001 for IgG and p=0.025 for IgM; respectively) and the LA-ve group (p=0.028, 0.02 and 0.001, respectively). Further multivariate logistic regression analysis showed that LA and of IgG and/or IgM aPS/PT were independent risk factors for thrombosis and pregnancy loss. In conclusion, aPS/PT, but not aPT, are more frequently found in patients with LA. Their association with thrombosis seems to be independent of the presence of LA. PMID:23254928

  14. Differences in intracellular calcium dynamics cause differences in α-granule secretion and phosphatidylserine expression in platelets adhering on glass and TiO2.

    PubMed

    Gupta, Swati; Donati, Alessia; Reviakine, Ilya

    2016-06-01

    In this study, the activation of purified human platelets due to their adhesion on glass and TiO2 in the absence of extracellular calcium was investigated. Differences in α-granule secretion between platelets adhering on the two surfaces were detected by examining the expression and secretion of the α-granule markers P-selectin (CD62P) and β-thromboglobulin. Similarly, differences in the expression of phosphatidylserine (PS), and in the activation of the major integrin GPIIb/IIIa, on the surfaces of the adhering platelets, were also observed. While all of these activation markers were expressed in platelets adhering on glass, the surface markers were not expressed in platelets adhering on TiO2, and β-thromboglobulin secretion levels were substantially reduced. Differences in marker expression and secretion correlated with differences in the intracellular calcium dynamics. Calcium ionophore treatment triggered α-granule secretion and PS expression in TiO2-adhering platelets but had no effect on the activation of GPIIb/IIIa. These results demonstrate specificity in the way surfaces of artificial materials activate platelets, link differences in the intracellular calcium dynamics observed in the platelets adhering on the two surfaces to the differences in some of the platelet responses (α-granule secretion and PS expression), but also highlight the involvement of synergistic, calcium-independent pathways in platelet activation. The ability to control activation in surface-adhering platelets makes this an attractive model system for studying platelet signaling pathways and for tissue engineering applications. PMID:27124595

  15. Cognitive effects of a dietary supplement made from extract of Bacopa monnieri, astaxanthin, phosphatidylserine, and vitamin E in subjects with mild cognitive impairment: a noncomparative, exploratory clinical study

    PubMed Central

    Zanotta, Danilo; Puricelli, Silvana; Bonoldi, Guido

    2014-01-01

    A prospective cohort, noncomparative, multicenter trial was conducted to explore the potential of a phytotherapeutic compound, available as a dietary supplement and containing extracts of Bacopa monnieri and Haematococcus pluvialis (astaxanthin) plus phosphatidylserine and vitamin E, in improving cognition in subjects diagnosed with mild cognitive impairment. Enrolled subjects (n=104) were aged 71.2±9.9 years and had a mini-mental state examination score of 26.0±2.0 (mean ± standard deviation). They underwent the Alzheimer’s Disease Assessment Scale-cognitive subscale (ADAS-cog) test and the clock drawing test at baseline and upon completion of a 60-day period of dietary supplementation with one tablet daily of the tested compound. In 102 assessable subjects, total ADAS-cog scores improved from 13.7±5.8 at baseline to 9.7±4.9 on day 60, and the clock drawing test scores improved from 8.5±2.3 to 9.1±1.9. Both changes were statistically significant (P<0.001). Memory tasks were the individual components of ADAS-cog showing the largest improvements. In a multivariate analysis, larger improvements in total ADAS-cog score were associated with less compromised baseline mini-mental state examination scores. Perceived efficacy was rated as excellent or good by 62% of study subjects. The tested compound was well tolerated; one nonserious adverse event was reported in the overall study population, and perceived tolerability was rated excellent or good by 99% of the subjects. In conclusion, dietary supplementation with the tested compound shows potential for counteracting cognitive impairment in subjects with mild cognitive impairment and warrants further investigation in adequately controlled, longer-term studies. PMID:24523587

  16. Tumor-specific targeting by Bavituximab, a phosphatidylserine-targeting monoclonal antibody with vascular targeting and immune modulating properties, in lung cancer xenografts.

    PubMed

    Gerber, David E; Hao, Guiyang; Watkins, Linda; Stafford, Jason H; Anderson, Jon; Holbein, Blair; Öz, Orhan K; Mathews, Dana; Thorpe, Philip E; Hassan, Gedaa; Kumar, Amit; Brekken, Rolf A; Sun, Xiankai

    2015-01-01

    Bavituximab is a chimeric monoclonal antibody with immune modulating and tumor-associated vascular disrupting properties demonstrated in models of non-small cell lung cancer (NSCLC). The molecular target of Bavituximab, phosphatidylserine (PS), is exposed on the outer leaflet of the membrane bi-layer of malignant vascular endothelial cells and tumor cells to a greater extent than on normal tissues. We evaluated the tumor-targeting properties of Bavituximab for imaging of NSCLC xenografts when radiolabeled with (111)In through conjugation with a bifunctional chelating agent, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). In vitro binding of (111)In-DOTA-Bavituximab to PS was determined by enzyme-linked immunosorbent assay (ELISA). Biodistribution of (111)In-DOTA-Bavituximab was conducted in normal rats, which provided data for dosimetry calculation. Single-photon emission computed tomography/computed tomography (SPECT/CT) imaging was performed in athymic nude rats bearing A549 NSCLC xenografts. At the molar conjugation ratio of 0.54 DOTA per Bavituximab, the PS binding affinity of (111)In-DOTA-Bavituximab was comparable to that of unmodified Bavituximab. Based on the quantitative SPECT/CT imaging data analysis, (111)In-DOTA-Bavituximab demonstrated tumor-specific uptake as measured by the tumor-tomuscle ratio, which peaked at 5.2 at 72 hr post-injection. In contrast, the control antibody only presented a contrast of 1.2 at the same time point.These findings may underlie the diagnostic efficacy and relative low rates of systemic vascular and immune-related toxicities of this immunoconjugate. Future applications of (111)In-DOTA-bavituximab may include prediction of efficacy, indication of tumor immunologic status, or characterization of radiographic findings. PMID:26550540

  17. Prevalence of antibodies to prothrombin in solid phase (aPT) and to phosphatidylserine-prothrombin complex (aPS/PT) in patients with and without lupus anticoagulant.

    PubMed

    Bertolaccini, Maria Laura; Sciascia, Savino; Murru, Veronica; Garcia-Fernandez, Cesar; Sanna, Giovanni; Khamashta, Munther A

    2013-02-01

    Antibodies to prothrombin in solid phase (aPT) and those to phosphatidiyserine-prothrombin complex (aPS/PT) have been suggested to strongly correlate with the presence of lupus anticoagulant (LA). As their clinical diagnostic value and true relationship with the LA remains elusive, we designed this study to evaluate the prevalence and significance of aPT and aPS/PT in a large cohort of patients with and without LA. Samples from 257 patients were included. aPT and aPS/PT were tested by ELISA. LA was tested as per the current criteria from the ISTH Subcommittee on LA-Phospholipid-dependent antibodies. aPS/PT and aPT were found in 51% and 32% of LA-positive (LA+ve) patients and in 22% and 28% of LA-negative (LA-ve) patients, respectively. Thrombosis, particularly venous thrombosis was associated with IgG aPT in the LA+ve group (p=0.0006) and in the LA-ve group (p=0.017). Antibodies to phosphatidylserine-prothrombin, either IgG and IgM were associated with thrombosis in general (p=0.0003) in particularly with venous thrombosis in the LA+ve group (p<0.0001 for IgG and p=0.025 for IgM; respectively) and the LA-ve group (p=0.028, 0.02 and 0.001, respectively). Further multivariate logistic regression analysis showed that LA and of IgG and/or IgM aPS/PT were independent risk factors for thrombosis and pregnancy loss. In conclusion, aPS/PT, but not aPT, are more frequently found in patients with LA. Their association with thrombosis seems to be independent of the presence of LA.

  18. Anti-prothrombin (aPT) and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies and the risk of thrombosis in the antiphospholipid syndrome. A systematic review.

    PubMed

    Sciascia, Savino; Sanna, Giovanni; Murru, Veronica; Roccatello, Dario; Khamashta, Munther A; Bertolaccini, Maria Laura

    2014-02-01

    Antibodies to prothrombin are detected by directly coating prothrombin on irradiated ELISA plates (aPT) or by using the phosphatidylserine/prothrombin complex as antigen (aPS/PT). Although these antibodies have both been associated with antiphospholipid syndrome (APS) and a correlation between the two assays have been reported, it seems that aPT and aPS/PT belong to different populations of autoantibodies. It was our objective to systematically review the available evidence on aPT and aPS/PT antibodies and the risk of thrombosis in APS. Medline-reports published between 1988 and 2013 investigating aPT and aPS/PT as a risk factor for thrombosis were included. Whenever possible, antibody isotype(s) and site of thrombosis were analysed. This systematic review is based on available data from more than 7,000 patients and controls from 38 studies analysing aPT and 10 aPS/PT. Antibodies to prothrombin (both aPT and aPS/PT) increased the risk of thrombosis (odds ratio [OR] 2.3; 95% confidence interval [CI] 1.72-3.5). aPS/PT seemed to represent a stronger risk factor for thrombosis, both arterial and/or venous than aPT (OR 5.11; 95%CI 4.2-6.3 and OR 1.82; 95%CI 1.44-2.75, respectively). In conclusion, routine measurement of aPS/PT (but not aPT) might be useful in establishing the thrombotic risk of patients with previous thrombosis and/or systemic lupus erythematosus. Their inclusion as laboratory criteria for the APS should be indisputably further explored.

  19. Kinetic analysis of mineral formation during in vitro modeling of matrix vesicle mineralization: effect of annexin A5, phosphatidylserine, and type II collagen.

    PubMed

    Genge, Brian R; Wu, Licia N Y; Wuthier, Roy E

    2007-08-15

    Matrix vesicles (MVs) are involved in de novo mineral formation by nearly all vertebrate tissues. The driving force for MV mineralization is a nucleational core composed of three principal constituents: (i) amorphous calcium phosphate (ACP), complexed in part with phosphatidylserine (PS) to form (ii) calcium-phosphate-lipid complexes (CPLX), and (iii) annexin A5 (AnxA5), the principal lipid-dependent Ca(2+)-binding protein in MVs. We describe methods for reconstituting the nucleational core using a biomimetic approach and for analyzing the kinetics of its induction of mineral formation. The method is based on light scattering by the nascent crystallites at 340 nm and monitors mineral formation at regular intervals without disturbing the system using an automated plate reader. It yields precise replicate values that typically agree within less than 5%. As with MVs, mineral formation by the synthetic complex follows a sigmoidal pattern; following a quiescent induction period, rapid formation ensues for a limited time, followed by a distinct decline in rate that continues to slow, ultimately reaching a maximal asymptotic value. Key to quantization of mineral formation is the use of first-derivative analysis, which defines the induction time, the rate and the amount of initial mineral formation. Furthermore, using a five-parameter logistic curve-fitting algorithm, the maximal amount of mineral formation can be predicted accurately. Using these methods, we document the dramatic finding that AnxA5 synergistically activates PS-CPLX, transforming it from a very weak nucleator of mineral formation to a potent one. The methods presented should enable systematic study of the effects of numerous other factors thought to contribute to mineral formation.

  20. Surface Phosphatidylserine Is Responsible for the Internalization on Microvesicles Derived from Hypoxia-Induced Human Bone Marrow Mesenchymal Stem Cells into Human Endothelial Cells

    PubMed Central

    Liu, Chaozhong; Wang, Lisheng; Xiao, Fengjun; Zhang, Hongchao

    2016-01-01

    Background Previous data have proven that microvesicles derived from hypoxia-induced mesenchymal stem cells (MSC-MVs) can be internalized into endothelial cells, enhancing their proliferation and vessel structure formation and promoting in vivo angiogenesis. However, there is a paucity of information about how the MSC-MVs are up-taken by endothelial cells. Methods MVs were prepared from the supernatants of human bone marrow MSCs that had been exposed to a hypoxic and/or serum-deprivation condition. The incorporation of hypoxia-induced MSC-MVs into human umbilical cord endothelial cells (HUVECs) was observed by flow cytometry and confocal microscopy in the presence or absence of recombinant human Annexin-V (Anx-V) and antibodies against human CD29 and CD44. Further, small interfering RNA (siRNA) targeted at Anx-V and PSR was delivered into HUVECs, or HUVECs were treated with a monoclonal antibody against phosphatidylserine receptor (PSR) and the cellular internalization of MVs was re-assessed. Results The addition of exogenous Anx-V could inhibit the uptake of MVs isolated from hypoxia-induced stem cells by HUVECs in a dose- and time-dependent manner, while the anti-CD29 and CD44 antibodies had no effect on the internalization process. The suppression was neither observed in Anx-V siRNA-transfected HUVECs, however, addition of anti-PSR antibody and PSR siRNA-transfected HUVECs greatly blocked the incorporation of MVs isolated from hypoxia-induced stem cells into HUVECs. Conclusion PS on the MVs isolated from hypoxia-induced stem cells is the critical molecule in the uptake by HUVECs. PMID:26808539

  1. Reversible digital images

    NASA Astrophysics Data System (ADS)

    Knox, Keith T.

    1999-04-01

    A method has been developed to hide one image inside another with little loss in image quality. If the second image is a logo or watermark, then this method may be used to protect the ownership rights of the first image and to guarantee the authenticity of the image. The two images to be combined may be either black & white or color continuous tone images. A reversible image is created by incorporating the first image in the upper 4 bits and the second image in the lower 4 bits. When viewed normally, the reversible image appears to be the first image. To view the hidden image, the bits of the combined image are reversed, exchanging all of the lower and higher order bits. When viewed in the reversed mode, the image appears to be the second or hidden image. To maintain a high level of image quality for both images, two simultaneous error diffusion calculations are run to ensure that both views of the reversible image have the same visual appearance as the originals. Any alteration of one of the images locally destroys the other image at the site of the alterations. This provides a method to detect alterations of the original image.

  2. Reversible collisionless magnetic reconnection

    SciTech Connect

    Ishizawa, A.; Watanabe, T.-H.

    2013-10-15

    Reversible magnetic reconnection is demonstrated for the first time by means of gyrokinetic numerical simulations of a collisionless magnetized plasma. Growth of a current-driven instability in a sheared magnetic field is accompanied by magnetic reconnection due to electron inertia effects. Following the instability growth, the collisionless reconnection is accelerated with development of a cross-shaped structure of current density, and then all field lines are reconnected. The fully reconnected state is followed by the secondary reconnection resulting in a weakly turbulent state. A time-reversed simulation starting from the turbulent state manifests that the collisionless reconnection process proceeds inversely leading to the initial state. During the reversed reconnection, the kinetic energy is reconverted into the original magnetic field energy. In order to understand the stability of reversed process, an external perturbation is added to the fully reconnected state, and it is found that the accelerated reconnection is reversible when the deviation of the E × B streamlines due to the perturbation is comparable with or smaller than a current layer width.

  3. Sequential Polarity-Reversing Circuit

    NASA Technical Reports Server (NTRS)

    Labaw, Clayton C.

    1994-01-01

    Proposed circuit reverses polarity of electric power supplied to bidirectional dc motor, reversible electro-mechanical actuator, or other device operating in direction depending on polarity. Circuit reverses polarity each time power turned on, without need for additional polarity-reversing or direction signals and circuitry to process them.

  4. Reversing Discrimination: A Perspective

    ERIC Educational Resources Information Center

    Pati, Gopal; Reilly, Charles W.

    1977-01-01

    Examines the debate over affirmative action and reverse discrimination, and discusses how and why the present dilemma has developed. Suggests that organizations can best address the problem through an honest, in-depth analysis of their organizational structure and management practices. (JG)

  5. Reverse Coherent Information

    NASA Astrophysics Data System (ADS)

    García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.

    2009-04-01

    We define a family of entanglement distribution protocols assisted by classical feedback communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This protocol family leads to the definition of a new entanglement distribution capacity that exceeds the unassisted entanglement distribution capacity for some interesting channels.

  6. Reverse Coherent Information

    NASA Astrophysics Data System (ADS)

    García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.

    2009-05-01

    In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.

  7. Time reversal communication system

    DOEpatents

    Candy, James V.; Meyer, Alan W.

    2008-12-02

    A system of transmitting a signal through a channel medium comprises digitizing the signal, time-reversing the digitized signal, and transmitting the signal through the channel medium. The channel medium may be air, earth, water, tissue, metal, and/or non-metal.

  8. Reversing Underachievement through Enrichment.

    ERIC Educational Resources Information Center

    Renzulli, Joseph S.; Baum, Susan M.; Hebert, Thomas; McCluskey, Ken W.

    1999-01-01

    Discusses problems of underachievement, especially among potentially high ability students, and the difficulties inherent in reversing this process. Presents new perspective and strategies that promote success. Describes Type III enrichment experiences as a means to unleash students' potential. Speculates as to what causes turnaround within an…

  9. Reverse coherent information.

    PubMed

    García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H

    2009-05-29

    In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.

  10. Justice and Reverse Discrimination

    ERIC Educational Resources Information Center

    Strike, Kenneth A.

    1976-01-01

    Although this article does not necessarily recommend policies of reverse discrimination, arguments indicating that such policies are not contradictory to accepted concepts of justice are presented. The necessity of dispersing any consequent injury to society as a whole rather than to individuals is stressed. (RW)

  11. Specificity of Lipoprotein-Associated Phospholipase A2 Towards Oxidized Phosphatidylserines: LC-ESI-MS Characterization of Products and Computer Modeling of Interactions

    PubMed Central

    Tyurin, Vladimir A.; Yanamala, Naveena; Tyurina, Yulia Y.; Klein-Seetharaman, Judith; Macphee, Colin H.; Kagan, Valerian E.

    2013-01-01

    Ca2+ independent lipoprotein associated phospholipase A2 (Lp-PLA2) is a member of the phospholipase A2 superfamily with a distinguishing characteristic of high specificity for oxidatively modified sn-2 fatty acid residues in phospholipids which has been especially well characterized for peroxidized species of phosphatidylcholines (PC). The ability of Lp-PLA2 to hydrolyze peroxidized species of phosphatidylserine (PS) – acting as a recognition signal for clearance of apoptotic cells by professional phagocytes - as well as the products of the reaction have not been investigated. We performed LC-MS-ESI-based structural characterization of oxygenated/hydrolyzed molecular species of PS - containing linoleic acid in either sn-2 position (C18:0/C18:2) or in both sn-1 and sn-2 positions (C18:2/C18:2) - formed in cytochrome c/ H2O2 driven enzymatic oxidation reaction. Cytochrome c has been chosen as a catalyst of peroxidation reactions due to its likely involvement in PS oxidation in apoptotic cells. We found that Lp-PLA2 catalyzed the hydrolysis of both non-truncated and truncated (oxidatively fragmented) species of oxidized PS species albeit with different efficiencies and performed detailed characterization of the major reaction products – oxygenated derivatives of linoleic acid as well as non-oxygenated and oxygenated species of lyso-PS. Among linoleic acid products, derivatives oxygenated at the C9 position, including 9-hydroxyoctadecadienoic acid (9-HODE) – a potent ligand of G protein-coupled receptor G2A - were the most abundant. Computer modeling of interactions of Lp-PLA2 with different PS oxidized species indicated that they are able to bind in proximity (<5Å) to Ser273 and His351 of the catalytic triad. For 9-hydroxy- and 9-hydroperoxy- derivatives of oxidized PS, the sn-2 ester bond was positioned within the very close proximity (<3Å) from the Ser273 residue - a nucleophile directly attacking the sn-2 bond – thus favoring the hydrolysis reaction. We

  12. Gridded electron reversal ionizer

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor)

    1993-01-01

    A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.

  13. Reversed field pinch diagnostics

    SciTech Connect

    Weber, P.G.

    1986-01-01

    The Reversed Field Pinch (RFP) is a toroidal, axisymmetric magnetic confinement configuration characterized by a magnetic field configuration in which the toroidal magnetic field is of similar strength to the poloidal field, and is reversed at the edge compared to the center. The RFP routinely operates at high beta, and is a strong candidate for a compact fusion device. Relevant attributes of the configuration will be presented, together with an overview of present and planned experiments and their diagnostics. RFP diagnostics are in many ways similar to those of other magnetic confinement devices (such as tokamaks); these lectures will point out pertinent differences, and will present some diagnostics which provide special insights into unique attributes of the RFP.

  14. Reverse genetics of mononegavirales.

    PubMed

    Conzelmann, K K

    2004-01-01

    "Reverse genetics" or de novo synthesis of nonsegmented negative-sense RNA viruses (Mononegavirales) from cloned cDNA has become a reliable technique to study this group of medically important viruses. Since the first generation of a negative-sense RNA virus entirely from cDNA in 1994, reverse genetics systems have been established for members of most genera of the Rhabdo-, Paramyxo-, and Filoviridae families. These systems are based on intracellular transcription of viral full-length RNAs and simultaneous expression of viral proteins required to form the typical viral ribonucleoprotein complex (RNP). These systems are powerful tools to study all aspects of the virus life cycle as well as the roles of virus proteins in virus-host interplay and pathogenicity. In addition, recombinant viruses can be designed to have specific properties that make them attractive as biotechnological tools and live vaccines. PMID:15298166

  15. Reversible watermarking for images

    NASA Astrophysics Data System (ADS)

    van Leest, Arno J.; van der Veen, Michiel; Bruekers, Fons

    2004-06-01

    Reversible watermarking is a technique for embedding data in a digital host signal in such a manner that the original host signal can be restored in a bit-exact manner in the restoration process. In this paper, we present a general framework for reversible watermarking in multi-media signals. A mapping function, which is in general neither injective nor surjective, is used to map the input signal to a perceptually equivalent output signal. The resulting unused sample values of the output signal are used to encode additional (watermark) information and restoration data. At the 2003 SPIE conference, examples of this technique applied to digital audio were presented. In this paper we concentrate on color and gray-scale images. A particular challenge in this context is not only the optimization of rate-distortion, but also the measure of perceptual quality (i.e. the distortion). In literature distortion is often expressed in terms of PSNR, making comparison among different techniques relatively straightforward. We show that our general framework for reversible watermarking applies to digital images and that results can be presented in terms of PSNR rate-distortions. However, the framework allows for more subtle signal manipulations that are not easily expressed in terms of PSNR distortion. These changes involve manipulations of contrast and/or saturation.

  16. Reversible DNA compaction.

    PubMed

    González-Pérez, Alfredo

    2014-01-01

    In this review we summarize and discuss the different methods we can use to achieve reversible DNA compaction in vitro. Reversible DNA compaction is a natural process that occurs in living cells and viruses. As a result these process long sequences of DNA can be concentrated in a small volume (compacted) to be decompacted only when the information carried by the DNA is needed. In the current work we review the main artificial compacting agents looking at their suitability for decompaction. The different approaches used for decompaction are strongly influenced by the nature of the compacting agent that determines the mechanism of compaction. We focus our discussion on two main artificial compacting agents: multivalent cations and cationic surfactants that are the best known compacting agents. The reversibility of the process can be achieved by adding chemicals like divalent cations, alcohols, anionic surfactants, cyclodextrins or by changing the chemical nature of the compacting agents via pH modifications, light induced conformation changes or by redox-reactions. We stress the relevance of electrostatic interactions and self-assembly as a main approach in order to tune up the DNA conformation in order to create an on-off switch allowing a transition between coil and compact states. The recent advances to control DNA conformation in vitro, by means of molecular self-assembly, result in a better understanding of the fundamental aspects involved in the DNA behavior in vivo and serve of invaluable inspiration for the development of potential biomedical applications. PMID:24444152

  17. Periodic Arrays of Interfacial Cylindrical reverse Micelles

    SciTech Connect

    Nelson,M.; Cain, N.; Ocko, B.; Gin, D.; Hammond, S.; Schwartz, D.

    2005-01-01

    We report an approach for the fabrication of periodic molecular nanostructures on surfaces. The approach involves biomimetic self-organization of synthetic wedge-shaped amphiphilic molecules into multilayer arrays of cylindrical reverse micelles. The films were characterized by atomic force microscopy and X-ray reflectivity. These nanostructured films self-assemble in solution but remain stable upon removal and exposure to ambient conditions, making them potentially suitable for a variety of dry pattern transfer methods. We illustrate the generality of this approach by using two distinct molecular systems that vary in size by a factor of 2.

  18. Affirmative Action, or Reverse Discrimination?

    ERIC Educational Resources Information Center

    Dansby, Ike

    1996-01-01

    Determines the impact of affirmative action programs in response to charges that they are policies of reverse discrimination. Reviewing affirmative action programs submitted by Michigan State departments, researchers determined no reverse discrimination was apparent based on low numbers of reverse discrimination complaints filed by whites. (GR)

  19. Reversal bending fatigue testing

    SciTech Connect

    Wang, Jy-An John; Wang, Hong; Tan, Ting

    2014-10-21

    Embodiments for apparatuses for testing reversal bending fatigue in an elongated beam are disclosed. Embodiments are configured to be coupled to first and second end portions of the beam and to apply a bending moment to the beam and create a pure bending condition in an intermediate portion of the beam. Embodiments are further configured to cyclically alternate the direction of the bending moment applied to the beam such that the intermediate portion of the beam cyclically bends in opposite directions in a pure bending condition.

  20. Depression of contraction and the calcium transient in single cardiomyocytes with acute ethanol exposure

    SciTech Connect

    Rozanski, D.J.; Delaville, F.J.; Thomas, A.P. )

    1992-01-01

    The mechanism by which acute ethanol (ET) exposure causes reversible myocardial dysfunction is unknown. The purpose of this study was to examine the effects of ET exposure on contraction and cytosolic free Ca[sup 2+] ([Ca[sup 2+

  1. Biochemical Reversal of Aging

    NASA Astrophysics Data System (ADS)

    Ely, John T. A.

    2006-03-01

    We cite our progress on biochemical reversal of aging. However, it may be circa 2 years before we have necessary substances at low cost. Meanwhile, without them, a number of measures can be adopted providing marked improvement for the problems of aging in modern societies. For example, enzymes are needed to excrete toxins that accelerate aging; Hg is the ultimate toxin that disables all enzymes (including those needed to excrete Hg itself). Low Hg level in the urine, due to loss of excretory ability, causes the diagnosis of Hg toxicity to almost always be missed. Hg sources must be removed from the body! Another example is excess sugar; hyperglycemia decreases intracellular ascorbic acid (AA) by competitively inhibiting the insulin- mediated active transport of AA into cells. Thus, immunity is impaired by low leucocyte AA. AA is needed for new proteins in aging tissues. Humans must supplement AA; their need same as in AA-synthesizing mammals.

  2. Reverse slapper detonator

    SciTech Connect

    Weingart, Richard C.

    1990-01-01

    A reverse slapper detonator (70), and methodology related thereto, are provided. The detonator (70) is adapted to be driven by a pulse of electric power from an external source (80). A conductor (20) is disposed along the top (14), side (18), and bottom (16) surfaces of a sheetlike insulator (12). Part of the conductor (20) comprises a bridge (28), and an aperture (30) is positioned within the conductor (20), with the bridge (28) and the aperture (30) located on opposite sides of the insulator (12). A barrel (40) and related explosive charge (50) are positioned adjacent to and in alignment with the aperture (30), and the bridge (28) is buttressed with a backing layer (60). When the electric power pulse vaporizes the bridge (28), a portion of the insulator (12) is propelled through the aperture (30) and barrel (40), and against the explosive charge (50), thereby detonating it.

  3. Reversed-polarity regions

    NASA Technical Reports Server (NTRS)

    Tang, F.

    1982-01-01

    It is found by a statistical study of 58 reversed-polarity regions (RPRs) covering the 11-year period 1969-1979 that RPRs (1) have a lifespan comparable to normal active regions, (2) do not show a tendency to rotate toward a more normal alignment, and (3) have stable configurations that do not suggest stress due to their anomalous magnetic alignment. As in normal regions, RPR magnetic complexity is found to be the primary factor in flare productivity. Weak-field RPRs produce no flares, and regions with complex spots produce more flares than regions with non-complex spots by a factor of five. The main difference between RPRs and normal regions lies in complex spot frequency, with less that 17% of normal active regions having such spots and fewer than 1.8% having long-lived complex ones, while 41% of RPRs have complex spots and 24% have long-lived complex spots.

  4. Properly apply reverse osmosis

    SciTech Connect

    Kucera, J.

    1997-02-01

    Reverse osmosis (RO) is a water purification technique used to reduce the loading of dissolved solids in solution. The popularity of RO for treating boiler feedwater is growing because of the rising cost of ion-exchange-based demineralization as well as safety concerns associated with handling acid and caustic. A properly designed and operated RO-based boiler-feedwater-treatment system can reduce the load to, and costs associated with, ion exchange demineralization. This article discusses RO feedwater quality recommendations, pretreatment techniques, and system monitoring necessary to achieve optimum RO system performance in the most cost-effective manner. Regardless of the application--whether it is the treatment of boiler feedwater, industrial wastewater, or process water--the approach to pretreatment and the other design and operating guidance offered here remains the same.

  5. Reverse Osmosis Optimization

    SciTech Connect

    McMordie Stoughton, Kate; Duan, Xiaoli; Wendel, Emily M.

    2013-08-26

    This technology evaluation was prepared by Pacific Northwest National Laboratory on behalf of the U.S. Department of Energy’s Federal Energy Management Program (FEMP). ¬The technology evaluation assesses techniques for optimizing reverse osmosis (RO) systems to increase RO system performance and water efficiency. This evaluation provides a general description of RO systems, the influence of RO systems on water use, and key areas where RO systems can be optimized to reduce water and energy consumption. The evaluation is intended to help facility managers at Federal sites understand the basic concepts of the RO process and system optimization options, enabling them to make informed decisions during the system design process for either new projects or recommissioning of existing equipment. This evaluation is focused on commercial-sized RO systems generally treating more than 80 gallons per hour.¬

  6. Reverse Osmosis Optimization

    SciTech Connect

    2013-08-01

    This technology evaluation was prepared by Pacific Northwest National Laboratory on behalf of the U.S. Department of Energy’s Federal Energy Management Program (FEMP). The technology evaluation assesses techniques for optimizing reverse osmosis (RO) systems to increase RO system performance and water efficiency. This evaluation provides a general description of RO systems, the influence of RO systems on water use, and key areas where RO systems can be optimized to reduce water and energy consumption. The evaluation is intended to help facility managers at Federal sites understand the basic concepts of the RO process and system optimization options, enabling them to make informed decisions during the system design process for either new projects or recommissioning of existing equipment. This evaluation is focused on commercial-sized RO systems generally treating more than 80 gallons per hour.

  7. Reverse photoacoustic standoff spectroscopy

    DOEpatents

    Van Neste, Charles W.; Senesac, Lawrence R.; Thundat, Thomas G.

    2011-04-12

    A system and method are disclosed for generating a reversed photoacoustic spectrum at a greater distance. A source may emit a beam to a target and a detector measures signals generated as a result of the beam being emitted on the target. By emitting a chopped/pulsed light beam to the target, it may be possible to determine the target's optical absorbance by monitoring the intensity of light collected at the detector at different wavelengths. As the wavelength of light is changed, the target may absorb or reject each optical frequency. Rejection may increase the intensity at the sensing element and absorption may decrease the intensity. Accordingly, an identifying spectrum of the target may be made with the intensity variation of the detector as a function of illuminating wavelength.

  8. Defining the Polar Field Reversal

    NASA Technical Reports Server (NTRS)

    Upton, Lisa; Hathaway, David H.

    2013-01-01

    The polar fields on the Sun are directly related to solar cycle variability. Recently there has been interest in studying an important characteristic of the polar fields: the timing of the polar field reversals. However this characteristic has been poorly defined, mostly due to the limitations of early observations. In the past, the reversals have been calculated by averaging the flux above some latitude (i.e. 55deg or 75deg). Alternatively, the reversal could be defined by the time in which the previous polarity is completely canceled and replaced by the new polarity at 90de, precisely at the pole. We will use a surface flux transport model to illustrate the differences in the timing of the polar field reversal based on each of these definitions and propose standardization in the definition of the polar field reversal. The ability to predict the timing of the polar field reversal using a surface flux transport model will also be discussed.

  9. Geomagnetic Reversals during the Phanerozoic.

    PubMed

    McElhinny, M W

    1971-04-01

    An antalysis of worldwide paleomagnetic measurements suggests a periodicity of 350 x 10(6) years in the polarity of the geomagnetic field. During the Mesozoic it is predominantly normal, whereas during the Upper Paleozoic it is predominantly reversed. Although geomagnetic reversals occur at different rates throughout the Phanerozoic, there appeaars to be no clear correlation between biological evolutionary rates and reversal frequency. PMID:17735224

  10. Raf-1 kinase possesses distinct binding domains for phosphatidylserine and phosphatidic acid. Phosphatidic acid regulates the translocation of Raf-1 in 12-O-tetradecanoylphorbol-13-acetate-stimulated Madin-Darby canine kidney cells.

    PubMed

    Ghosh, S; Strum, J C; Sciorra, V A; Daniel, L; Bell, R M

    1996-04-01

    Previous studies demonstrated that the cysteine-rich amino-terminal domain of Raf-1 kinase interacts selectively with phosphatidylserine (Ghosh, S., Xie, W. Q., Quest, A. F. G., Mabrouk, G. M., Strum, J. C., and Bell, R. M. (1994) J. Biol. Chem. 269, 10000-10007). Further analysis showed that full-length Raf-1 bound to both phosphatidylserine and phosphatidic acid (PA). Specifically, a carboxyl-terminal domain of Raf-1 kinase (RafC; residues 295 648 of human Raf-1) interacted strongly with phosphatidic acid. The binding of RafC to PA displayed positive cooperativity with Hill numbers between 3.3 and 6.2; the apparent Kd ranged from 4.9 +/- 0.6 to 7.8 +/- 0.9 mol % PA. The interaction of RafC with PA displayed a pH dependence distinct from the interaction between the cysteine-rich domain of Raf-1 and PA. Also, the RafC-PA interaction was unaffected at high ionic strength. Of all the lipids tested, only PA and cardiolipin exhibited high affinity binding; other acidic lipids were either ineffective or weakly effective. By deletion mutagenesis, the PA binding site within RafC was narrowed down to a 35-amino acid segment between residues 389 and 423. RafC did not bind phosphatidyl alcohols; also, inhibition of PA formation in Madin-Darby canine kidney cells by treatment with 1% ethanol significantly reduced the translocation of Raf-1 from the cytosol to the membrane following stimulation with 12-O-tetradecanoylphorbol-13-acetate. These results suggest a potential role of the lipid second messenger, PA, in the regulation of translocation and subsequent activation of Raf-1 in vivo.

  11. EXPOSURE ANALYSIS

    EPA Science Inventory

    This proceedings chapter will discuss the state-of-the-science regarding the evaluation of exposure as it relates to water quality criteria (WQC), sediment quality guidelines (SQG), and wildlife criteria (WC). Throughout this discussion, attempts are made to identify the methods ...

  12. Hypotonic exposures.

    PubMed

    Flynn, W J; Hill, R M

    1984-03-01

    Even without a contact lens, the cornea can suffer adverse physiological changes from hypotonic exposure, as well as the associated subjective phenomena (e.g., halo and rainbows). The contact lens adds a dimension to this problem that should be viewed against a background of normal (non-wearing) susceptibilities. PMID:6715776

  13. Erythrocyte Shrinkage and Cell Membrane Scrambling after Exposure to the Ionophore Nonactin.

    PubMed

    Peter, Thomas; Bissinger, Rosi; Lang, Florian

    2016-02-01

    The ionophore antibiotic nonactin permeabilizes cell membranes to NH4+ and K(+) . Treatment of erythrocytes with nonactin is expected to trigger cellular K(+) loss with subsequent cell shrinkage, which in turn is known to trigger suicidal death of a wide variety of cells including erythrocytes. This study explored whether nonactin exposure induces eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and translocation of cell membrane phosphatidylserine to the erythrocyte surface. Signalling of eryptosis includes increase in cytosolic Ca(2+) activity [(Ca(2+) )i ] and stimulation of protein kinase C (PKC) as well as p38 mitogen-activated protein kinase. Phosphatidylserine abundance at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter (FSC) and (Ca(2+) )i from Fluo3-fluorescence. A 48-hr treatment of human erythrocytes with nonactin significantly decreased FSC (≥10 ng/ml) and significantly increased the percentage of annexin-V-binding cells (≥10 ng/ml), effects paralleled by increase in (Ca(2+) )i (≥50 ng/ml) and virtually abrogated by increase in extracellular K(+) concentration to 120 mM at the expense of Na(+) . The up-regulation of annexin-V-binding after nonactin treatment was significantly blunted but not abolished by the removal of extracellular Ca(2+) and by addition of either PKC inhibitor staurosporine (0.4 μM) or p38 kinase inhibitor SB203580 (2 μM). In conclusion, exposure of erythrocytes to the K(+) ionophore nonactin induces erythrocyte shrinkage and subsequent erythrocyte membrane scrambling, effects involving cellular K(+) loss, Ca(2+) entry and activation of staurosporine as well as SB203580-sensitive kinases.

  14. Time-Reversal Violation

    NASA Astrophysics Data System (ADS)

    Bernabéu, José; Martínez-Vidal, Fernando

    2015-10-01

    The violation of CP symmetry between matter and antimatter in the neutral K and B meson systems is well established, with a high degree of consistency between all available experimental measurements and with the Standard Model of particle physics. On the basis of the up-to-now-unbroken CPT symmetry, the violation of CP symmetry strongly suggests that the behavior of these particles under weak interactions must also be asymmetric under time reversal T. Many searches for T violation have been performed and proposed using different observables and experimental approaches. These include T-odd observables, such as triple products in weak decays, and genuine observables, such as permanent electric dipole moments of nondegenerate stationary states and the breaking of the reciprocity relation. We discuss the conceptual basis of the required exchange of initial and final states with unstable particles, using quantum entanglement and the decay as a filtering measurement, for the case of neutral B and K mesons. Using this method, the BaBar experiment at SLAC has clearly observed T violation in B mesons.

  15. Reversible micromachining locator

    DOEpatents

    Salzer, Leander J.; Foreman, Larry R.

    1999-01-01

    This invention provides a device which includes a locator, a kinematic mount positioned on a conventional tooling machine, a part carrier disposed on the locator and a retainer ring. The locator has disposed therein a plurality of steel balls, placed in an equidistant position circumferentially around the locator. The kinematic mount includes a plurality of magnets which are in registry with the steel balls on the locator. In operation, a blank part to be machined is placed between a surface of a locator and the retainer ring (fitting within the part carrier). When the locator (with a blank part to be machined) is coupled to the kinematic mount, the part is thus exposed for the desired machining process. Because the locator is removably attachable to the kinematic mount, it can easily be removed from the mount, reversed, and reinserted onto the mount for additional machining. Further, the locator can likewise be removed from the mount and placed onto another tooling machine having a properly aligned kinematic mount. Because of the unique design and use of magnetic forces of the present invention, positioning errors of less than 0.25 micrometer for each machining process can be achieved.

  16. Reversible micromachining locator

    DOEpatents

    Salzer, L.J.; Foreman, L.R.

    1999-08-31

    This invention provides a device which includes a locator, a kinematic mount positioned on a conventional tooling machine, a part carrier disposed on the locator and a retainer ring. The locator has disposed therein a plurality of steel balls, placed in an equidistant position circumferentially around the locator. The kinematic mount includes a plurality of magnets which are in registry with the steel balls on the locator. In operation, a blank part to be machined is placed between a surface of a locator and the retainer ring (fitting within the part carrier). When the locator (with a blank part to be machined) is coupled to the kinematic mount, the part is thus exposed for the desired machining process. Because the locator is removably attachable to the kinematic mount, it can easily be removed from the mount, reversed, and reinserted onto the mount for additional machining. Further, the locator can likewise be removed from the mount and placed onto another tooling machine having a properly aligned kinematic mount. Because of the unique design and use of magnetic forces of the present invention, positioning errors of less than 0.25 micrometer for each machining process can be achieved. 7 figs.

  17. Time Reversal Violation

    SciTech Connect

    Quinn, H; /SLAC

    2009-01-27

    This talk briefly reviews three types of time-asymmetry in physics, which I classify as universal, macroscopic and microscopic. Most of the talk is focused on the latter, namely the violation of T-reversal invariance in particle physics theories. In sum tests of microscopic T-invariance, or observations of its violation, are limited by the fact that, while we can measure many processes, only in very few cases can we construct a matched pair of process and inverse process and observe it with sufficient sensitivity to make a test. In both the cases discussed here we can achieve an observable T violation making use of flavor tagging, and in the second case also using the quantum properties of an antisymmetric coherent state of two B mesons to construct a CP-tag. Both these tagging properties depend only on very general properties of the flavor and/or CP quantum numbers and so provide model independent tests for T-invariance violations. The microscopic laws of physics are very close to T-symmetric. There are small effects that give CP- and T-violating processes in three-generation-probing weak decays. Where a T-violating observable can be constructed we see the relationships between T-violation and CP-violation expected in a CPT conserving theory. These microscopic effects are unrelated to the 'arrow of time' that is defined by increasing entropy, or in the time direction defined by the expansion of our Universe.

  18. Reverse hierarchical PIV processing

    NASA Astrophysics Data System (ADS)

    Rohály, J.; Frigerio, F.; Hart, D. P.

    2002-07-01

    A novel hierarchical processing scheme is proposed to efficiently increase the spatial resolution and dynamic range of detecting particle image displacements in PIV images. The technique takes full advantage of the multi-resolution characteristic of the discrete correlation function by starting the processing at the smallest scale and, if necessary, gradually building correlation planes into larger interrogation areas based on the result of inter-level correlation correction and validation. It is shown that the algorithm can be implemented in both direct and FFT based correlation algorithms with greatly reduced computational complexity. The technique opens new perspectives for locally adaptive super-resolution processing taking flow field, seeding, and imaging anomalies into account. Processing at the lowest scale (e.g. pixel or particle image size) allows the combination of correlation planes on any shape. Hence the proposed reverse hierarchical processing represents interrogation area optimization both in size and shape in order to maximize the correlation plane signal-to-noise ratio. The method is successfully demonstrated on experimentally obtained images.

  19. Reversible Energy-Transfer Switching on a DNA Scaffold

    PubMed Central

    2015-01-01

    We show that FRET between Pacific Blue (PB) and Alexa488 (A488) covalently attached to a DNA scaffold can be reversibly controlled by photochromic switching of a spiropyran derivative. With the spiropyran in the closed spiro isomeric form, FRET occurs freely between PB and A488. UV-induced isomerization to the open merocyanine form shuts down the FRET process by efficient quenching of the PB excited state. The process is reversed by exposure to visible light, triggering the isomerization to the spiro isomer. PMID:25687828

  20. Reverse Transfer Project, Summer 1986.

    ERIC Educational Resources Information Center

    Reis, Elizabeth

    In 1986, a Reverse Transfer Project was initiated at Moraine Valley Community College (MVCC) in order to promote the summer school attendance at MVCC of "reverse transfer" students (i.e., students who attended another institution during the regular academic year). A mailing, containing a cover letter, informational brochure, summer catalog, and…

  1. Preference Reversal in Multiattribute Choice

    ERIC Educational Resources Information Center

    Tsetsos, Konstantinos; Usher, Marius; Chater, Nick

    2010-01-01

    A central puzzle for theories of choice is that people's preferences between options can be reversed by the presence of decoy options (that are not chosen) or by the presence of other irrelevant options added to the choice set. Three types of reversal effect reported in the decision-making literature, the attraction, compromise, and similarity…

  2. Exposure chamber

    DOEpatents

    Moss, Owen R.; Briant, James K.

    1983-01-01

    An exposure chamber includes an imperforate casing having a fluid inlet at the top and an outlet at the bottom. A single vertical series of imperforate trays is provided. Each tray is spaced on all sides from the chamber walls. Baffles adjacent some of the trays restrict and direct the flow to give partial flow back and forth across the chambers and downward flow past the lowermost pan adjacent a central plane of the chamber.

  3. Classical Analog to Entanglement Reversibility

    NASA Astrophysics Data System (ADS)

    Chitambar, Eric; Fortescue, Ben; Hsieh, Min-Hsiu

    2015-08-01

    In this Letter we study the problem of secrecy reversibility. This asks when two honest parties can distill secret bits from some tripartite distribution pX Y Z and transform secret bits back into pX Y Z at equal rates using local operation and public communication. This is the classical analog to the well-studied problem of reversibly concentrating and diluting entanglement in a quantum state. We identify the structure of distributions possessing reversible secrecy when one of the honest parties holds a binary distribution, and it is possible that all reversible distributions have this form. These distributions are more general than what is obtained by simply constructing a classical analog to the family of quantum states known to have reversible entanglement. An indispensable tool used in our analysis is a conditional form of the Gács-Körner common information.

  4. The Geomagnetic Field During a Reversal

    NASA Technical Reports Server (NTRS)

    Heirtzler, James R.

    2003-01-01

    By modifying the IGRF it is possible to learn what may happen to the geomagnetic field during a geomagnetic reversal. If the entire IGRF reverses then the declination and inclination only reverse when the field strength is zero. If only the dipole component of the IGRF reverses a large geomagnetic field remains when the dipole component is zero and he direction of the field at the end of the reversal is not exactly reversed from the directions at the beginning of the reversal.

  5. Reverse osmosis reverses conventional wisdom with Superfund cleanup success

    SciTech Connect

    Collins, M. ); Miller, K. )

    1994-09-01

    Although widely recognized as the most efficient means of water purification, reverse osmosis has not been considered effective for remediating hazardous wastewater. Scaling and fouling, which can cause overruns and downtime, and require membrane replacement, have inhibited success in high-volume wastewater applications. Despite this background, a reverse osmosis technology developed in Europe recently was used successfully to treat large volumes of contaminated water at a major Superfund site in Texas. The technology's success there may increase the chances for reverse osmosis to find wider use in future cleanups and other waste treatment applications.

  6. Periodic reversal of direction allows Myxobacteria to swarm

    PubMed Central

    Wu, Yilin; Kaiser, A. Dale; Jiang, Yi; Alber, Mark S.

    2009-01-01

    Many bacteria can rapidly traverse surfaces from which they are extracting nutrient for growth. They generate flat, spreading colonies, called swarms because they resemble swarms of insects. We seek to understand how members of any dense swarm spread efficiently while being able to perceive and interfere minimally with the motion of others. To this end, we investigate swarms of the myxobacterium, Myxococcus xanthus. Individual M. xanthus cells are elongated; they always move in the direction of their long axis; and they are in constant motion, repeatedly touching each other. Remarkably, they regularly reverse their gliding directions. We have constructed a detailed cell- and behavior-based computational model of M. xanthus swarming that allows the organization of cells to be computed. By using the model, we are able to show that reversals of gliding direction are essential for swarming and that reversals increase the outflow of cells across the edge of the swarm. Cells at the swarm edge gain maximum exposure to nutrient and oxygen. We also find that the reversal period predicted to maximize the outflow of cells is the same (within the errors of measurement) as the period observed in experiments with normal M. xanthus cells. This coincidence suggests that the circuit regulating reversals evolved to its current sensitivity under selection for growth achieved by swarming. Finally, we observe that, with time, reversals increase the cell alignment, and generate clusters of parallel cells. PMID:19164578

  7. Supercritical fluid reverse micelle separation

    DOEpatents

    Fulton, John L.; Smith, Richard D.

    1993-01-01

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W.sub.o that determines the maximum size of the reverse micelles. The maximum ratio W.sub.o of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions.

  8. Supercritical fluid reverse micelle separation

    DOEpatents

    Fulton, J.L.; Smith, R.D.

    1993-11-30

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W[sub o] that determines the maximum size of the reverse micelles. The maximum ratio W[sub o] of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions. 27 figures.

  9. Criminal exposure.

    PubMed

    1999-09-01

    In August, an HIV-positive man plead guilty to sexually assaulting a 14-year-old boy. The sleeping boy awoke to find [name removed] sexually assaulting him, while watching a pornographic video. [Name removed] plead guilty to the assault with intent to rape a child. In addition, [name removed] received three counts of indecent assault and battery on a child, and exposure of pornographic material to a minor. [Name removed] will remain on probation for five years, although the prosecution had recommended sentencing [name removed] to four or five years in prison. The boy continues to be tested for HIV.

  10. Lanczos iterated time-reversal.

    PubMed

    Oberai, Assad A; Feijóo, Gonzalo R; Barbone, Paul E

    2009-02-01

    A new iterative time-reversal algorithm capable of identifying and focusing on multiple scatterers in a relatively small number of iterations is developed. It is recognized that the traditional iterated time-reversal method is based on utilizing power iterations to determine the dominant eigenpairs of the time-reversal operator. The convergence properties of these iterations are known to be suboptimal. Motivated by this, a new method based on Lanczos iterations is developed. In several illustrative examples it is demonstrated that for the same number of transmitted and received signals, the Lanczos iterations based approach is substantially more accurate. PMID:19206835

  11. Reverse mortgage decision-making.

    PubMed

    Leviton, R

    2001-01-01

    Reverse mortgages have been suggested as a promising financial tool to help low-income older homeowners who want to remain in their houses. However, actual use of this option has been much below early estimates of potential demand. This study explored response to the new option through open-ended interviews of homeowners who had received reverse mortgage counseling. Decision-making was influenced by attachment to home, family input, and financial attitudes, including desire to leave a legacy. In general, homeowners took reverse mortgages only as a "last resort" that enabled them to maintain their independence.

  12. Reversal of phenol and naphthalene effects on ciliate chemoattraction

    SciTech Connect

    Berk, S.G.; Ting, R.S.; Roberts, R.O. ); Mills, B.A. ); Stewart, K.C. )

    1990-02-01

    In an effort to address research needs in the area of rapid screening tests for aquatic toxicology, the authors engaged in a study of pollutant effects on protozoan chemoattraction. Among pollutants tested were metals and hydrocarbons. To ascertain whether inhibition observed after brief exposures to certain concentrations of the pollutants were irreversible, they examined the possibility of nullifying the inhibitory effect by removing protozoa from the toxicants after short exposures. Earlier work showed that inhibitory effects of metals could be removed, and they report here the nullification and reversibility of effects of phenol and naphthalene on certain ciliates.

  13. Magnetization reversal in exchange biased nanocap arrays

    NASA Astrophysics Data System (ADS)

    Guhr, I. L.; van Dijken, S.; Malinowski, G.; Fischer, P.; Springer, F.; Hellwig, O.; Albrecht, M.

    2007-05-01

    Arrays of self-assembled polystyrene spheres with various particle sizes have been used as a substrate to study the exchange bias effect along the out-of-plane direction of Pt/Co multilayers capped with IrMn layers. The evolution of the reversal process of the resulting magnetic nanocaps was investigated by magnetic force microscopy (MFM) and magnetic transmission x-ray microscopy (M-TXM). Tip-sample interaction-induced irreversible and reversible switching events have been observed during multiple scanning cycles in MFM imaging which are ascribed to the so-called training effect. During M-TXM imaging a drastic change in morphology has been found due to the x-ray exposure, leading to the formation of much larger spherical particles. Interestingly, these merged particles reveal again an exchange coupled single-domain magnetic cap with magnetic behaviour similar to magnetic films deposited directly on spheres of similar size. This paper was presented at the Materials Research Society Fall 2006 Meeting, 27 November-1 December 2006, as part of Symposium P: Nanoscale Magnets-Synthesis, Self-assembly, Properties and Applications, organized by J Fassbender, J Chapman and C A Ross.

  14. Reverse Discrimination and Aggressive Behavior.

    ERIC Educational Resources Information Center

    Johnson, Stephen D.

    1980-01-01

    White subjects were aggressive toward Black opponents when contest results appeared to reflect elements of reverse discrimination; but they showed less aggressive behavior toward Black opponents when they thought their loss was due to their opponents' superior ability. (RL)

  15. Deciphering records of geomagnetic reversals

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Fournier, Alexandre

    2016-06-01

    Polarity reversals of the geomagnetic field are a major feature of the Earth's dynamo. Questions remain regarding the dynamical processes that give rise to reversals and the properties of the geomagnetic field during a polarity transition. A large number of paleomagnetic reversal records have been acquired during the past 50 years in order to better constrain the structure and geometry of the transitional field. In addition, over the past two decades, numerical dynamo simulations have also provided insights into the reversal mechanism. Yet despite the large paleomagnetic database, controversial interpretations of records of the transitional field persist; they result from two characteristics inherent to all reversals, both of which are detrimental to an ambiguous analysis. On the one hand, the reversal process is rapid and requires adequate temporal resolution. On the other hand, weak field intensities during a reversal can affect the fidelity of magnetic recording in sedimentary records. This paper is aimed at reviewing critically the main reversal features derived from paleomagnetic records and at analyzing some of these features in light of numerical simulations. We discuss in detail the fidelity of the signal extracted from paleomagnetic records and pay special attention to their resolution with respect to the timing and mechanisms involved in the magnetization process. Records from marine sediments dominate the database. They give rise to transitional field models that often lead to overinterpret the data. Consequently, we attempt to separate robust results (and their subsequent interpretations) from those that do not stand on a strong observational footing. Finally, we discuss new avenues that should favor progress to better characterize and understand transitional field behavior.

  16. Acute stress impairs set-shifting but not reversal learning.

    PubMed

    Butts, K A; Floresco, S B; Phillips, A G

    2013-09-01

    The ability to update and modify previously learned behavioral responses in a changing environment is essential for successful utilization of promising opportunities and for coping with adverse events. Valid models of cognitive flexibility that contribute to behavioral flexibility include set-shifting and reversal learning. One immediate effect of acute stress is the selective impairment of performance on higher-order cognitive control tasks mediated by the medial prefrontal cortex (mPFC) but not the hippocampus. Previous studies show that the mPFC is required for set-shifting but not for reversal learning, therefore the aim of the present experiment is to assess whether exposure to acute stress (15 min of mild tail-pinch stress) given immediately before testing on either a set-shifting or reversal learning tasks would impair performance selectively on the set-shifting task. An automated operant chamber-based task, confirmed that exposure to acute stress significantly disrupts set-shifting but has no effect on reversal learning. Rats exposed to an acute stressor require significantly more trials to reach criterion and make significantly more perseverative errors. Thus, these data reveal that an immediate effect of acute stress is to impair mPFC-dependent cognition selectively by disrupting the ability to inhibit the use of a previously relevant cognitive strategy.

  17. Reverse Current in Solar Flares

    NASA Technical Reports Server (NTRS)

    Knight, J. W., III

    1978-01-01

    An idealized steady state model of a stream of energetic electrons neutralized by a reverse current in the pre-flare solar plasma was developed. These calculations indicate that, in some cases, a significant fraction of the beam energy may be dissipated by the reverse current. Joule heating by the reverse current is a more effective mechanism for heating the plasma than collisional losses from the energetic electrons because the Ohmic losses are caused by thermal electrons in the reverse current which have much shorter mean free paths than the energetic electrons. The heating due to reverse currents is calculated for two injected energetic electron fluxes. For the smaller injected flux, the temperature of the coronal plasma is raised by about a factor of two. The larger flux causes the reverse current drift velocity to exceed the critical velocity for the onset of ion cyclotron turbulence, producing anomalous resistivity and an order of magnitude increase in the temperature. The heating is so rapid that the lack of ionization equilibrium may produce a soft X-ray and EUV pulse from the corona.

  18. 14 CFR 33.97 - Thrust reversers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .... This test may be scheduled as part of the endurance run. (b) 175 reversals must be made from flight-idle forward thrust to maximum reverse thrust and 25 reversals must be made from rated takeoff...

  19. 14 CFR 33.97 - Thrust reversers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    .... This test may be scheduled as part of the endurance run. (b) 175 reversals must be made from flight-idle forward thrust to maximum reverse thrust and 25 reversals must be made from rated takeoff...

  20. 14 CFR 33.97 - Thrust reversers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    .... This test may be scheduled as part of the endurance run. (b) 175 reversals must be made from flight-idle forward thrust to maximum reverse thrust and 25 reversals must be made from rated takeoff...

  1. 14 CFR 33.97 - Thrust reversers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .... This test may be scheduled as part of the endurance run. (b) 175 reversals must be made from flight-idle forward thrust to maximum reverse thrust and 25 reversals must be made from rated takeoff...

  2. Visual hydrogen detector with variable reversibility

    NASA Technical Reports Server (NTRS)

    Muradov, Nazim (Inventor)

    2011-01-01

    Methods, processes and compositions are provided for a visual or chemochromic hydrogen-detector with variable or tunable reversible color change. The working temperature range for the hydrogen detector is from minus 100.degree. C. to plus 500.degree. C. A hydrogen-sensitive pigment, including, but not limited to, oxides, hydroxides and polyoxo-compounds of tungsten, molybdenum, vanadium, chromium and combinations thereof, is combined with nano-sized metal activator particles and preferably, coated on a porous or woven substrate. In the presence of hydrogen, the composition rapidly changes its color from white or light-gray or light-tan to dark gray, navy-blue or black depending on the exposure time and hydrogen concentration in the medium. After hydrogen exposure ceases, the original color of the hydrogen-sensitive pigment is restored, and the visual hydrogen detector can be used repeatedly. By changing the composition of the hydrogen-sensitive pigment, the time required for its complete regeneration is varied from a few seconds to several days.

  3. Reverse shift mechanism for automotive manual transmission

    SciTech Connect

    Inui, M.; Ogawa, S.

    1987-03-03

    A reverse shift mechanism is described for an automotive manual transmission of a type having a reverse idler gear which is movable to selectively complete a reverse gear train, the reverse shift mechanism comprising: a reverse shift arm having a portion disposed adjacent the reverse idler gear and pivotally carried with respect to a transmission casing so that the portion rocks along a direction of axis of the reverse idler gear in response to shifting operation. The portion of the reverse shift arm is provided with a blind hole which is open at a first end toward the reverse idler gear and is closed at a second end away from the reverse idler gear; and a shift arm shoe carried by the portion of the reverse shift arm adjacent the reverse idler gear for pushing the reverse idler gear. The shift arm shoe has an end adapted to engage with a circumferential groove formed in the reverse idler gear and an opposing end shaped to fit in the blind hole of the reverse shift arm; whereby the shift arm shoe is prevented from coming off during assembly by virtue of a vacuum effect created by air confined in the blind hole by fitting engagement between the opposing end and the blind hole, and is held in place after assembly by being clamped between the groove of the reverse idler gear and the blind hole of the reverse shift arm.

  4. Dynamics and timing of reversals

    NASA Astrophysics Data System (ADS)

    Valet, J.-P.; Fournier, A.

    2012-04-01

    Information provided by records of geomagnetic reversals from lava sequences is constrained by irregular volcanic activity. We show that, despite different resolution, the ten most detailed volcanic records match surprisingly well and display the same dynamical characteristics after tuning to a common eruption rate. We thus infer that the reversal process has remained unchanged over the past 180Ma with the same time constants and duration. The reversing field is characterized by 3 successive episodes, a precursory event, a 180° polarity switch and a rebound. The first and third phases depict a large amplitude directional change which, by comparison with the archeological record, is estimated to last between 2 and 2.5 kyr. The transit between the two polarities does not exceed 1ka and is thus too fast for being properly recorded by most sediments. Similar results are obtained after reducing the directional clusters that are present at different periods in each record. These features and time constants are compatible with models that do not require any mantle control on reversals processes, which is also supported by the absence of preferred longitude of the pole. Lastly, based on the chronology of the successive reversal phases, the eruption rates are found to be at least twice larger for hot spots (<1flow/100yr) than for large flood basaltic provinces.

  5. Vasectomy reversal: a clinical update.

    PubMed

    Patel, Abhishek P; Smith, Ryan P

    2016-01-01

    Vasectomy is a safe and effective method of contraception used by 42-60 million men worldwide. Approximately 3%-6% of men opt for a vasectomy reversal due to the death of a child or divorce and remarriage, change in financial situation, desire for more children within the same marriage, or to alleviate the dreaded postvasectomy pain syndrome. Unlike vasectomy, vasectomy reversal is a much more technically challenging procedure that is performed only by a minority of urologists and places a larger financial strain on the patient since it is usually not covered by insurance. Interest in this procedure has increased since the operating microscope became available in the 1970s, which consequently led to improved patency and pregnancy rates following the procedure. In this clinical update, we discuss patient evaluation, variables that may influence reversal success rates, factors to consider in choosing to perform vasovasostomy versus vasoepididymostomy, and the usefulness of vasectomy reversal to alleviate postvasectomy pain syndrome. We also review the use of robotics for vasectomy reversal and other novel techniques and instrumentation that have emerged in recent years to aid in the success of this surgery. PMID:26975488

  6. Vasectomy reversal: a clinical update

    PubMed Central

    Patel, Abhishek P; Smith, Ryan P

    2016-01-01

    Vasectomy is a safe and effective method of contraception used by 42–60 million men worldwide. Approximately 3%–6% of men opt for a vasectomy reversal due to the death of a child or divorce and remarriage, change in financial situation, desire for more children within the same marriage, or to alleviate the dreaded postvasectomy pain syndrome. Unlike vasectomy, vasectomy reversal is a much more technically challenging procedure that is performed only by a minority of urologists and places a larger financial strain on the patient since it is usually not covered by insurance. Interest in this procedure has increased since the operating microscope became available in the 1970s, which consequently led to improved patency and pregnancy rates following the procedure. In this clinical update, we discuss patient evaluation, variables that may influence reversal success rates, factors to consider in choosing to perform vasovasostomy versus vasoepididymostomy, and the usefulness of vasectomy reversal to alleviate postvasectomy pain syndrome. We also review the use of robotics for vasectomy reversal and other novel techniques and instrumentation that have emerged in recent years to aid in the success of this surgery. PMID:26975488

  7. Exposure chamber

    DOEpatents

    Moss, Owen R.

    1980-01-01

    A chamber for exposing animals, plants, or materials to air containing gases or aerosols is so constructed that catch pans for animal excrement, for example, serve to aid the uniform distribution of air throughout the chamber instead of constituting obstacles as has been the case in prior animal exposure chambers. The chamber comprises the usual imperforate top, bottom and side walls. Within the chamber, cages and their associated pans are arranged in two columns. The pans are spaced horizontally from the walls of the chamber in all directions. Corresponding pans of the two columns are also spaced horizontally from each other. Preferably the pans of one column are also spaced vertically from corresponding pans of the other column. Air is introduced into the top of the chamber and withdrawn from the bottom. The general flow of air is therefore vertical. The effect of the horizontal pans is based on the fact that a gas flowing past the edge of a flat plate that is perpendicular to the flow forms a wave on the upstream side of the plate. Air flows downwardly between the chamber walls and the outer edges of the pan. It also flows downwardly between the inner edges of the pans of the two columns. It has been found that when the air carries aerosol particles, these particles are substantially uniformly distributed throughout the chamber.

  8. Interferon Regulatory Factor-1 (IRF-1) Is Involved in the Induction of Phosphatidylserine Receptor (PSR) in Response to dsRNA Virus Infection and Contributes to Apoptotic Cell Clearance in CHSE-214 Cell

    PubMed Central

    Kung, Hsin-Chia; Evensen, Øystein; Hong, Jiann-Ruey; Kuo, Chia-Yu; Tso, Chun-Hsi; Ngou, Fang-Huar; Lu, Ming-Wei; Wu, Jen-Leih

    2014-01-01

    The phosphatidylserine receptor (PSR) recognizes a surface marker on apoptotic cells and initiates engulfment. This receptor is important for effective apoptotic cell clearance and maintains normal tissue homeostasis and regulation of the immune response. However, the regulation of PSR expression remains poorly understood. In this study, we determined that interferon regulatory factor-1 (IRF-1) was dramatically upregulated upon viral infection in the fish cell. We observed apoptosis in virus-infected cells and found that both PSR and IRF-1 increased simultaneously. Based on a bioinformatics promoter assay, IRF-1 binding sites were identified in the PSR promoter. Compared to normal viral infection, we found that PSR expression was delayed, viral replication was increased and virus-induced apoptosis was inhibited following IRF-1 suppression with morpholino oligonucleotides. A luciferase assay to analyze promoter activity revealed a decreasing trend after the deletion of the IRF-1 binding site on PSR promoter. The results of this study indicated that infectious pancreatic necrosis virus (IPNV) infection induced both the apoptotic and interferon (IFN) pathways, and IRF-1 was involved in regulating PSR expression to induce anti-viral effects. Therefore, this work suggests that PSR expression in salmonid cells during IPNV infection is activated when IRF-1 binds the PSR promoter. This is the first report to show the potential role of IRF-1 in triggering the induction of apoptotic cell clearance-related genes during viral infection and demonstrates the extensive crosstalk between the apoptotic and innate immune response pathways. PMID:25342322

  9. Noise exposure and public health.

    PubMed Central

    Passchier-Vermeer, W; Passchier, W F

    2000-01-01

    Exposure to noise constitutes a health risk. There is sufficient scientific evidence that noise exposure can induce hearing impairment, hypertension and ischemic heart disease, annoyance, sleep disturbance, and decreased school performance. For other effects such as changes in the immune system and birth defects, the evidence is limited. Most public health impacts of noise were already identified in the 1960s and noise abatement is less of a scientific but primarily a policy problem. A subject for further research is the elucidation of the mechanisms underlying noise-induced cardiovascular disorders and the relationship of noise with annoyance and nonacoustical factors modifying health outcomes. A high priority study subject is the effects of noise on children, including cognitive effects and their reversibility. Noise exposure is on the increase, especially in the general living environment, both in industrialized nations and in developing world regions. This implies that in the twenty-first century noise exposure will still be a major public health problem. Images Figure 2 PMID:10698728

  10. Ice ages and geomagnetic reversals

    NASA Technical Reports Server (NTRS)

    Wu, Patrick

    1992-01-01

    There have been speculations on the relationship between climatic cooling and polarity reversals of the earth's magnetic field during the Pleistocene. Two of the common criticisms on this relationship have been the reality of these short duration geomagnetic events and the accuracy of their dates. Champion et al. (1988) have reviewed recent progress in this area. They identified a total of 10 short-duration polarity events in the last 1 Ma and 6 of these events have been found in volcanic rocks, which also have K-Ar dates. Supposing that the speculated relationship between climatic cooling and geomagnetic reversals actually exist, two mechanisms that assume climatic cooling causes short period magnetic reversals will be investigated. These two methods are core-mantle boundary topography and transfer of the rotational energy to the core.

  11. Time-reversed, flow-reversed ballistics simulations

    SciTech Connect

    Zernow, L.; Chapyak, E. J.; Scheffler, D. R.

    2001-01-01

    Two-dimensional simulations of planar sheet jet formation are studied to examine the hydrodynamic issues involved when simulations are carried out in the inverse direction, that is, with reversed time and flow. Both a realistic copper equation of state and a shockless equation of state were used. These studies are an initial step in evaluating this technique as a ballistics design tool.

  12. Reversible binding kinetics of a cytoskeletal protein at the erythrocyte submembrane.

    PubMed Central

    Stout, A. L.; Axelrod, D.

    1994-01-01

    removed most of the band 3. CF-4.1 binded significantly less to these trypsinized membranes and most of the decrease was a loss of the irreversibly binding sites. The third treatment simply preserved the native 4.1 and ankyrin. CF-4.1 binded less to this sample too, and the loss involved both the irreversible and reversible sites. The fourth treatment blocked the gycophorin C sites on the native 4.1-stripped membranes with an antibody. CF-4.1 again binded less to this sample than to a nonimmune serum control, and almost all of the decrease is a loss of irreversible sites. These rest suggest that 1) protein 4.1 binds to membrane or submembrane sites at least in part reversibly ; 2) the most reversible sites are probably not proteinaceous and not glycophorin C, but possibly are phospholipids (especially phosphatidylserine); and 3) TIWRFRAP can successfully examine the fast reversible dynamics of cytoskeletal components binding to biological membranes. Images FIGURE 2 FIGURE 3 FIGURE 4 PMID:7811947

  13. Marburg Virus Reverse Genetics Systems

    PubMed Central

    Schmidt, Kristina Maria; Mühlberger, Elke

    2016-01-01

    The highly pathogenic Marburg virus (MARV) is a member of the Filoviridae family and belongs to the group of nonsegmented negative-strand RNA viruses. Reverse genetics systems established for MARV have been used to study various aspects of the viral replication cycle, analyze host responses, image viral infection, and screen for antivirals. This article provides an overview of the currently established MARV reverse genetic systems based on minigenomes, infectious virus-like particles and full-length clones, and the research that has been conducted using these systems. PMID:27338448

  14. Stagnation point reverse flow combustor

    NASA Technical Reports Server (NTRS)

    Zinn, Ben T. (Inventor); Neumeier, Yedidia (Inventor); Seitzman, Jerry M. (Inventor); Jagoda, Jechiel (Inventor); Weksler, Yoav (Inventor)

    2008-01-01

    A method for combusting a combustible fuel includes providing a vessel having an opening near a proximate end and a closed distal end defining a combustion chamber. A combustible reactants mixture is presented into the combustion chamber. The combustible reactants mixture is ignited creating a flame and combustion products. The closed end of the combustion chamber is utilized for directing combustion products toward the opening of the combustion chamber creating a reverse flow of combustion products within the combustion chamber. The reverse flow of combustion products is intermixed with combustible reactants mixture to maintain the flame.

  15. Reversing: A Fundamental Idea in Computer Science

    ERIC Educational Resources Information Center

    Armoni, Michal; Ginat, David

    2008-01-01

    Reversing is the notion of thinking or working in reverse. Computer science textbooks and tutors recognize it primarily in the form of recursion. However, recursion is only one form of reversing. Reversing appears in the computer science curriculum in many other forms, at various intellectual levels, in a variety of fundamental courses. As such,…

  16. A Note on Reverse Derivations

    ERIC Educational Resources Information Center

    Samman, M.

    2005-01-01

    In this note, the notion of reverse derivation is studied. It is shown that in the class of semiprime rings, this notion coincides with the usual derivation when it maps a semiprime ring into its centre. However, we provide some examples to show that it is not the case in general.

  17. CAPSULE REPORT: REVERSE OSMOSIS PROCESS

    EPA Science Inventory

    A failure analysis has been completed for the reverse osmosis (RO) process. The focus was on process failures that result in releases of liquids and vapors to the environment. The report includes the following: 1) A description of RO and coverage of the principles behind the proc...

  18. Reversible colour change in Arthropoda.

    PubMed

    Umbers, Kate D L; Fabricant, Scott A; Gawryszewski, Felipe M; Seago, Ainsley E; Herberstein, Marie E

    2014-11-01

    The mechanisms and functions of reversible colour change in arthropods are highly diverse despite, or perhaps due to, the presence of an exoskeleton. Physiological colour changes, which have been recorded in 90 arthropod species, are rapid and are the result of changes in the positioning of microstructures or pigments, or in the refractive index of layers in the integument. By contrast, morphological colour changes, documented in 31 species, involve the anabolism or catabolism of components (e.g. pigments) directly related to the observable colour. In this review we highlight the diversity of mechanisms by which reversible colour change occurs and the evolutionary context and diversity of arthropod taxa in which it has been observed. Further, we discuss the functions of reversible colour change so far proposed, review the limited behavioural and ecological data, and argue that the field requires phylogenetically controlled approaches to understanding the evolution of reversible colour change. Finally, we encourage biologists to explore new model systems for colour change and to engage scientists from other disciplines; continued cross-disciplinary collaboration is the most promising approach to this nexus of biology, physics, and chemistry.

  19. Can luteal regression be reversed?

    PubMed Central

    Telleria, Carlos M

    2006-01-01

    The corpus luteum is an endocrine gland whose limited lifespan is hormonally programmed. This debate article summarizes findings of our research group that challenge the principle that the end of function of the corpus luteum or luteal regression, once triggered, cannot be reversed. Overturning luteal regression by pharmacological manipulations may be of critical significance in designing strategies to improve fertility efficacy. PMID:17074090

  20. Law: Reverse Discrimination, Legal Briefs

    ERIC Educational Resources Information Center

    Nation's Schools and Colleges, 1974

    1974-01-01

    Just as schools and colleges are starting to hire more black and female faculty members through affirmative action programs, there is a new battle cry on the civil rights front: "reverse discrimination." Qualified whites claim they are being shoved aside in the scramble for less-qualified blacks, Chicanos, American Indians, and members of other…

  1. Quotas Are Not Reverse Discrimination

    ERIC Educational Resources Information Center

    McDonald, Gabrielle K.

    1975-01-01

    The findings of the Morrow v. Crisler and NAACP v. Allen civil rights cases are discussed. It is concluded from these employment discrimination cases that quotas are not reverse discrimination because no one has the right to continue to receive the benefits of racial discrimination at the expense of others. (LBH)

  2. Reversion phenomena of Cu-Cr alloys

    NASA Technical Reports Server (NTRS)

    Nishikawa, S.; Nagata, K.; Kobayashi, S.

    1985-01-01

    Cu-Cr alloys which were given various aging and reversion treatments were investigated in terms of electrical resistivity and hardness. Transmission electron microscopy was one technique employed. Some results obtained are as follows: the increment of electrical resistivity after the reversion at a constant temperature decreases as the aging temperature rises. In a constant aging condition, the increment of electrical resistivity after the reversion increases, and the time required for a maximum reversion becomes shorter as the reversion temperature rises. The reversion phenomena can be repeated, but its amount decreases rapidly by repetition. At first, the amount of reversion increases with aging time and reaches its maximum, and then tends to decrease again. Hardness changes by the reversion are very small, but the hardness tends to soften slightly. Any changes in transmission electron micrographs by the reversion treatment cannot be detected.

  3. ECOLOGICAL AND EVOLUTIONARY APPLICATIONS FOR ENVIRONMENTAL SEX REVERSAL OF FISH.

    PubMed

    Mcnair, Alistair; Lokman, P Mark; Closs, Gerard P; Nakagawa, Shinichi

    2015-03-01

    Environmental sex reversal (ESR), which results in a mismatch between genotypic and phenotypic sex, is well documented in numerous fish species and may be induced by chemical exposure. Historically, research involving piscine ESR has been carried out with a view to improving profitability in aquaculture or to elucidate the processes governing sex determination and sexual differentiation. However, recent studies in evolution and ecology suggest research on ESR now has much wider applications and ramifications. We begin with an overview of ESR in fish and a brief review of the traditional applications thereof. We then discuss ESR and its potential demographic consequences in wild populations. Theory even suggests sex-reversed fish may be purposefully released to manipulate population dynamics. We suggest new research directions that may prove fruitful in understanding how ESR at the individual level translates to population-level processes. In the latter portion of the review we focus on evolutionary applications of ESR. Sex-reversal studies from the aquaculture literature provide insight in to the evolvability of determinants of sexual phenotype. Additionally, induced sex reversal can provide information about the evolution of sex chromosomes and sex-linked traits. Recently, naturally occurring ESR has been implicated as a mechanism contributing to the evolution of sex chromosomes.

  4. Reversal agents in anaesthesia and critical care

    PubMed Central

    Pani, Nibedita; Dongare, Pradeep A; Mishra, Rajeeb Kumar

    2015-01-01

    Despite the advent of short and ultra-short acting drugs, an in-depth knowledge of the reversal agents used is a necessity for any anaesthesiologist. Reversal agents are defined as any drug used to reverse the effects of anaesthetics, narcotics or potentially toxic agents. The controversy on the routine reversal of neuromuscular blockade still exists. The advent of newer reversal agents like sugammadex have made the use of steroidal neuromuscular blockers like rocuronium feasible in rapid sequence induction situations. We made a review of the older reversal agents and those still under investigation for drugs that are regularly used in our anaesthesia practice. PMID:26644615

  5. The 94- to 97-kDa mouse macrophage membrane protein that recognizes oxidized low density lipoprotein and phosphatidylserine-rich liposomes is identical to macrosialin, the mouse homologue of human CD68.

    PubMed Central

    Ramprasad, M P; Fischer, W; Witztum, J L; Sambrano, G R; Quehenberger, O; Steinberg, D

    1995-01-01

    We have previously reported the partial purification of a 94- to 97-kDa plasma membrane protein from mouse peritoneal macrophages that binds oxidatively modified low density lipoprotein (OxLDL) and phosphatidylserine-rich liposomes. We have now identified that protein as macrosialin, a previously cloned macrophage-restricted membrane protein in the lysosomal-associated membrane protein family (mouse homologue of human CD68). Early in the course of purification of the 94- to 97-kDa protein, a new OxLDL-binding band at 190-200 kDa appeared and copurified with the 94- to 97-kDa protein. The HPLC pattern of tryptic peptides from this higher molecular mass ligand-binding band closely matched that derived from the 94- to 97-kDa band. Specifically, the same three macrosialin-derived tryptic peptides (9, 9, and 15 residues) were present in the purified 94- to 97-kDa band and in the 190- to 200-kDa band and antisera raised against peptide sequences in macrosialin recognized both bands. An antiserum against macrosialin precipitated most of the 94- to 97-kDa OxLDL-binding material. We conclude that the binding of OxLDL to mouse macrophage membranes is in part attributable to macrosialin. Our previous studies show that OxLDL competes with oxidized red blood cells and with apoptotic thymocytes for binding to mouse peritoneal macrophages. Whether macrosialin plays a role in recognition of OxLDL and oxidatively damaged cells by intact macrophages remains uncertain. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:7568176

  6. Docosahexaenoic acid induces increases in [Ca2+]i via inositol 1,4,5-triphosphate production and activates protein kinase C gamma and -delta via phosphatidylserine binding site: implication in apoptosis in U937 cells.

    PubMed

    Aires, Virginie; Hichami, Aziz; Filomenko, Rodolphe; Plé, Aude; Rébé, Cédric; Bettaieb, Ali; Khan, Naim Akhtar

    2007-12-01

    We investigated, in monocytic leukemia U937 cells, the effects of docosahexaenoic acid (DHA; 22:6 n-3) on calcium signaling and determined the implication of phospholipase C (PLC) and protein kinase C (PKC) in this pathway. DHA induced dose-dependent increases in [Ca2+]i, which were contributed by intracellular pool, via the production of inositol-1,4,5-triphosphate (IP3) and store-operated Ca2+ (SOC) influx, via opening of Ca2+ release-activated Ca2+ (CRAC) channels. Chemical inhibition of PLC, PKCgamma, and PKCdelta, but not of PKCbeta I/II, PKCalpha, or PKCbetaI, significantly diminished DHA-induced increases in [Ca2+]i. In vitro PKC assays revealed that DHA induced a approximately 2-fold increase in PKCgamma and -delta activities, which were temporally correlated with the DHA-induced increases in [Ca2+]i. In cell-free assays, DHA, but not other structural analogs of fatty acids, activated these PKC isoforms. Competition experiments revealed that DHA-induced activation of both the PKCs was dose-dependently inhibited by phosphatidylserine (PS). Furthermore, DHA induced apoptosis via reactive oxygen species (ROS) production, followed by caspase-3 activation. Chemical inhibition of PKCgamma/delta and of SOC/CRAC channels significantly attenuated both DHA-stimulated ROS production and caspase-3 activity. Our study suggests that DHA-induced activation of PLC/IP3 pathway and activation of PKCgamma/delta, via its action on PS binding site, may be involved in apoptosis in U937 cells.

  7. [Reverse genetics and prenatal diagnosis].

    PubMed

    Plauchu, H

    1988-05-01

    "Reverse" genetics is a research process consisting in finding the gene of a disease, then in "descending" toward the final product that it codes. This reasoning is the reverse of the one normally used which "ascends from the protein to the gene" and can be applied to the discovery of the pathogenic mechanism of a disease. There are numerous spin-offs of this new type of approach for prenatal diagnosis (PND). Thus, the discovery of polymorphic tracers surrounding the gene enables an indirect PND in informative families. Reliability is great if we have many probes at our disposal. Then, discovery of the gene itself permits a direct PND with the use of intragenic probes and synthetic oligonucleotides.

  8. Reverse osmosis water purification system

    NASA Technical Reports Server (NTRS)

    Ahlstrom, H. G.; Hames, P. S.; Menninger, F. J.

    1986-01-01

    A reverse osmosis water purification system, which uses a programmable controller (PC) as the control system, was designed and built to maintain the cleanliness and level of water for various systems of a 64-m antenna. The installation operates with other equipment of the antenna at the Goldstone Deep Space Communication Complex. The reverse osmosis system was designed to be fully automatic; with the PC, many complex sequential and timed logic networks were easily implemented and are modified. The PC monitors water levels, pressures, flows, control panel requests, and set points on analog meters; with this information various processes are initiated, monitored, modified, halted, or eliminated as required by the equipment being supplied pure water.

  9. Reversing the Brazil Nut Effect

    NASA Astrophysics Data System (ADS)

    Ludewig, F.; Vandewalle, N.

    2005-12-01

    We propose a lattice model for studying the Brazil Nut Effect (BNE), i.e. the phase segregation occuring when a granular material is vertically shaked. The model considers the tap intensity and the mobility μ of the grains as the main physical parameters. Different mobilities for different grain species lead to segregation (BNE) patterns, reverse segregation (RBNE) patterns, “sandwhich" layered structures or vertical domains. A phase diagram (decompaction χ, mobility difference between both species Δ μ) is obtained in which the different phases are emphasized. In a narrow region of the diagram, different phases coexist. It is shown that the BNE segregation could be reversed by increasing the tap intensity or the characteristics of the grains. Numerical results are compared with earlier experimental works.

  10. A reversible nanoconfined chemical reaction.

    PubMed

    Nielsen, Thomas K; Bösenberg, Ulrike; Gosalawit, Rapee; Dornheim, Martin; Cerenius, Yngve; Besenbacher, Flemming; Jensen, Torben R

    2010-07-27

    Hydrogen is recognized as a potential, extremely interesting energy carrier system, which can facilitate efficient utilization of unevenly distributed renewable energy. A major challenge in a future "hydrogen economy" is the development of a safe, compact, robust, and efficient means of hydrogen storage, in particular, for mobile applications. Here we report on a new concept for hydrogen storage using nanoconfined reversible chemical reactions. LiBH4 and MgH2 nanoparticles are embedded in a nanoporous carbon aerogel scaffold with pore size Dmax approximately 21 nm and react during release of hydrogen and form MgB2. The hydrogen desorption kinetics is significantly improved compared to bulk conditions, and the nanoconfined system has a high degree of reversibility and stability and possibly also improved thermodynamic properties. This new scheme of nanoconfined chemistry may have a wide range of interesting applications in the future, for example, within the merging area of chemical storage of renewable energy.

  11. Reconstructing exposures from biomarkers using exposure-pharmacokinetic modeling--A case study with carbaryl.

    PubMed

    Brown, Kathleen; Phillips, Martin; Grulke, Christopher; Yoon, Miyoung; Young, Bruce; McDougall, Robin; Leonard, Jeremy; Lu, Jingtao; Lefew, William; Tan, Yu-Mei

    2015-12-01

    Sources of uncertainty involved in exposure reconstruction for short half-life chemicals were characterized using computational models that link external exposures to biomarkers. Using carbaryl as an example, an exposure model, the Cumulative and Aggregate Risk Evaluation System (CARES), was used to generate time-concentration profiles for 500 virtual individuals exposed to carbaryl. These exposure profiles were used as inputs into a physiologically based pharmacokinetic (PBPK) model to predict urinary biomarker concentrations. These matching dietary intake levels and biomarker concentrations were used to (1) compare three reverse dosimetry approaches based on their ability to predict the central tendency of the intake dose distribution; and (2) identify parameters necessary for a more accurate exposure reconstruction. This study illustrates the trade-offs between using non-iterative reverse dosimetry methods that are fast, less precise and iterative methods that are slow, more precise. This study also intimates the necessity of including urine flow rate and elapsed time between last dose and urine sampling as part of the biomarker sampling collection for better interpretation of urinary biomarker data of short biological half-life chemicals. Resolution of these critical data gaps can allow exposure reconstruction methods to better predict population-level intake doses from large biomonitoring studies.

  12. Eyespots in a reversible setting.

    PubMed

    Deregowski, Jan B; Gray, Colin D

    2013-01-01

    When eyespots were presented on a reversible figure, the total duration for which elements bearing the eyespots were seen as closer to the observer was found to be greater than the total for counterpart elements. It is speculated that the tendency to see eyespots as nearer than they really are is related to the manner in which they are responded to in nature. PMID:23700964

  13. Reverse engineering of integrated circuits

    DOEpatents

    Chisholm, Gregory H.; Eckmann, Steven T.; Lain, Christopher M.; Veroff, Robert L.

    2003-01-01

    Software and a method therein to analyze circuits. The software comprises several tools, each of which perform particular functions in the Reverse Engineering process. The analyst, through a standard interface, directs each tool to the portion of the task to which it is most well suited, rendering previously intractable problems solvable. The tools are generally used iteratively to produce a successively more abstract picture of a circuit, about which incomplete a priori knowledge exists.

  14. Reversible Seeding in Storage Rings

    SciTech Connect

    Ratner, Daniel; Chao, Alex; /SLAC

    2011-12-14

    We propose to generate steady-state microbunching in a storage ring with a reversible seeding scheme. High gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) are two promising methods for microbunching linac electron beams. Because both schemes increase the energy spread of the seeded beam, they cannot drive a coherent radiator turn-by-turn in a storage ring. However, reversing the seeding process following the radiator minimizes the impact on the electron beam and may allow coherent radiation at or near the storage ring repetition rate. In this paper we describe the general idea and outline a proof-of-principle experiment. Electron storage rings can drive high average power light sources, and free-electron lasers (FELs) are now producing coherent light sources of unprecedented peak brightness While there is active research towards high repetition rate FELs (for example, using energy recovery linacs), at present there are still no convenient accelerator-based sources of high repetition rate, coherent radiation. As an alternative avenue, we recently proposed to establish steady-state microbunching (SSMB) in a storage ring. By maintaining steady-state coherent microbunching at one point in the storage ring, the beam generates coherent radiation at or close to the repetition rate of the storage ring. In this paper, we propose a method of generating a microbunched beam in a storage ring by using reversible versions of linac seeding schemes.

  15. Reversible fluorescence photoswitching in DNA.

    PubMed

    Smith, Darren A; Holliger, Philipp; Flors, Cristina

    2012-08-30

    We describe the engineering of reversible fluorescence photoswitching in DNA with high-density substitution, and its applications in advanced fluorescence microscopy methods. High-density labeling of DNA with cyanine dyes can be achieved by polymerase chain reaction using a modified DNA polymerase that has been evolved to efficiently incorporate Cy3- and Cy5-labeled cytosine base analogues into double-stranded DNA. The resulting biopolymer, "CyDNA", displays hundreds of fluorophores per DNA strand and is strongly colored and highly fluorescent, although previous observations suggest that fluorescence quenching at such high density might be a concern, especially for Cy5. Herein, we first investigate the mechanisms of fluorescence quenching in CyDNA and we suggest that two different mechanisms, aggregate formation and resonance energy transfer, are responsible for fluorescence quenching at high labeling densities. Moreover, we have been able to re-engineer CyDNA into a reversible fluorescence photoswitchable biopolymer by using the properties of the Cy3-Cy5 pair. This novel biopolymer constitutes a new class of photoactive DNA-based nanomaterial and is of great interest for advanced microscopy applications. We show that reversible fluorescence photoswitching in CyDNA can be exploited in optical lock-in detection imaging. It also lays the foundations for improved and sequence-specific super-resolution fluorescence microscopy of DNA. PMID:22861666

  16. Three distinct reversing modes in the geodynamo

    NASA Astrophysics Data System (ADS)

    Gallet, Y.; Pavlov, V. E.

    2016-03-01

    The data that describe the long-term reversing behavior of the geodynamo show strong and sudden changes in magnetic reversal frequency. This concerns both the onset and the end of superchrons and most probably the occurrence of episodes characterized by extreme geomagnetic reversal frequency (>10-15 rev./Myr). To account for the complexity observed in geomagnetic reversal frequency evolution, we propose a simple scenario in which the geodynamo operates in three distinct reversing modes: i—a "normal" reversing mode generating geomagnetic polarity reversals according to a stationary random process, with on average a reversal rate of ˜3 rev./Myr; ii—a non-reversing "superchron" mode characterizing long time intervals without reversal; iii—a hyper-active reversing mode characterized by an extreme geomagnetic reversal frequency. The transitions between the different reversing modes would be sudden, i.e., on the Myr time scale. Following previous studies, we suggest that in the past, the occurrence of these transitions has been modulated by thermal conditions at the core-mantle boundary governed by mantle dynamics. It might also be possible that they were more frequent during the Precambrian, before the nucleation of the inner core, because of a stronger influence on geodynamo activity of the thermal conditions at the core-mantle boundary.

  17. Neuropsychological effects of exposure to naphtha among automotive workers.

    PubMed Central

    White, R F; Robins, T G; Proctor, S; Echeverria, D; Rocskay, A S

    1994-01-01

    The association between exposure to naphtha and neurobehavioural measures was examined prospectively over one year among workers employed at an automotive plant that used naphtha to calibrate fuel injectors. The neurobehavioural tests included those that assess mood, basic intelligence, and functioning of the cerebral frontal lobes and limbic system and were designed so that acute, reversible, and chronic effects of solvent exposure could be assessed. Participants were 248 workers in June 1988, and the testing was repeated on 185 of these workers in 1989. Concentrations of naphtha at the plant ranged from six to 709 mg/m3, although exposure was greater in 1988 than in 1989. Duration of exposure for individual subjects ranged from 0.8 to 7.3 years. Cross sectional data analyses showed significant associations between level of exposure to naphtha and slower timed scores on trails A, and greater reports of negative affective symptoms on profile of mood states scales in 1988 but not 1989. Threshold model analyses of the 1989 data showed an association between score on visual reproductions immediate recall and daily exposure to naphtha at or above 1050 h x mg/m3. Models of chronic exposure showed no associations between chronic exposure and negative neurobehavioural outcome. Results suggest that naphtha produces mild acute reversible effects on function of the central nervous system at or above daily exposures of 540 h x mg/m3 (approximately 90 ppm/h). PMID:8111457

  18. 14 CFR 33.97 - Thrust reversers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the engine incorporates a reverser, the endurance calibration, operation, and vibration tests prescribed...

  19. Rapid evaluation of reverse-osmosis membranes

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Simultaneous reverse-osmosis tests conducted with centrifuges having multiple compartment heads are discussed. Equipment for retaining reverse-osmosis membrane is illustrated. Method of conducting tests is described.

  20. A Reverse Shock in GRB 160509A

    NASA Astrophysics Data System (ADS)

    Laskar, T.; Alexander, K. D.; Berger, E.

    2016-10-01

    Through detailed multi-wavelength observations and modeling, we present the discovery and characterization a reverse shock in GRB 160509A. This result highlights the unique power of radio observations in the study of GRB reverse shocks.

  1. Ancient Magnetic Reversals: Clues to the Geodynamo.

    ERIC Educational Resources Information Center

    Hoffman, Kenneth A.

    1988-01-01

    Discusses the question posed by some that the earth's magnetic field may reverse. States that rocks magnetized by ancient fields may offer clues to the underlying reversal mechanism in the earth's core. (TW)

  2. Inhalation exposure of animals.

    PubMed Central

    Phalen, R F

    1976-01-01

    Relative advantages and disadvantages and important design criteria for various exposure methods are presented. Five types of exposures are discussed: whole-body chambers, head-only exposures, nose or mouth-only methods, lung-only exposures, and partial-lung exposures. Design considerations covered include: air cleaning and conditioning; construction materials; losses of exposure materials; evenness of exposure; sampling biases; animal observation and care; noise and vibration control, safe exhausts, chamber loading, reliability, pressure fluctuations; neck seals, masks, animal restraint methods; and animal comfort. Ethical considerations in use of animals in inhalation experiments are also discussed. PMID:1017420

  3. Transient and reversible nephrotoxicity of sarin in rats.

    PubMed

    Bloch-Shilderman, Eugenia; Levy, Aharon

    2007-01-01

    Organophosphate (OP) poisoning, which inhibits cholinesterase activity, leads to severe cholinergic symptoms. Effective and quick management of these symptoms is considered critical to the clinical outcome. Acute renal damage following exposure to OP insecticides has been reported. Similar complications might occur following exposure to OP nerve agents, however, this subject has been studied only sporadically. In the present study, the effect of the nerve agent sarin on renal function was examined in rats. A single dose of sarin ( approximately 0.9 LD(50)) led to a significant reduction (of 45%) in renal function during the first 2 days post exposure, as exhibited by evaluation of the glomerular filtration rate, through measuring the clearance of ( 99m)Tc-DTPA. The urine volume was reduced by 50%, the urine specific gravity increased to 104% of the control value and massive hematuria and glucosuria were recorded 24-48 h post exposure. In addition, around 60% decrease in urine electrolytes was monitored during the first 2 days following exposure, with a recovery after 8 days. Post mortem gross inspection of the bladder, 24 h post exposure, revealed severe edema and hemorrhage. Treatment with the muscarinic antagonist atropine and the oxime TMB-4, at excessive doses administered 1 min post exposure, did not prevent most renal impairments. It has been concluded that sarin caused an acute renal dysfunction, possibly accompanied by bladder damage. These impairments were reversible, recovered spontaneously within 3-8 days, and were probably related to the state of shock and hypovolemia caused by the poisoning. However, if renal impairments are left unattended, they might contribute to the overall toxic manifestation and as a result aggravate the clinical state of intoxicated casualties.

  4. Medium wave exposure characterisation using exposure quotients.

    PubMed

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Pinar, Iván

    2010-06-01

    One of the aspects considered in the International Commission on Non-Ionizing Radiation Protection guidelines is that, in situations of simultaneous exposure to fields of different frequencies, exposure quotients for thermal and electrical stimulation effects should be examined. The aim of the present work was to analyse the electromagnetic radiation levels and exposure quotients for exposure to multiple-frequency sources in the vicinity of medium wave radio broadcasting antennas. The measurements were made with a spectrum analyser and a monopole antenna. Kriging interpolation was used to prepare contour maps and to estimate the levels in the towns and villages of the zone. The results showed that the exposure quotient criterion based on electrical stimulation effects to be more stringent than those based on thermal effects or power density levels. Improvement of dosimetry evaluations requires the spectral components of the radiation to be quantified, followed by application of the criteria for exposure to multiple-frequency sources. PMID:20159912

  5. Medium wave exposure characterisation using exposure quotients.

    PubMed

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Pinar, Iván

    2010-06-01

    One of the aspects considered in the International Commission on Non-Ionizing Radiation Protection guidelines is that, in situations of simultaneous exposure to fields of different frequencies, exposure quotients for thermal and electrical stimulation effects should be examined. The aim of the present work was to analyse the electromagnetic radiation levels and exposure quotients for exposure to multiple-frequency sources in the vicinity of medium wave radio broadcasting antennas. The measurements were made with a spectrum analyser and a monopole antenna. Kriging interpolation was used to prepare contour maps and to estimate the levels in the towns and villages of the zone. The results showed that the exposure quotient criterion based on electrical stimulation effects to be more stringent than those based on thermal effects or power density levels. Improvement of dosimetry evaluations requires the spectral components of the radiation to be quantified, followed by application of the criteria for exposure to multiple-frequency sources.

  6. Neurotoxicity and Immunotoxicity Outcomes following Gestational Exposure to Four Lab Drinking Water Concentrates

    EPA Science Inventory

    To evaluate whether developmental exposure to drinking water concentrates altered other endpoints, standard neuro- and immunotoxicity tests were conducted on the offspring. Male and female offspring (10/sex/treatment) exposed to chlorinated concentrated water (CCW) or reverse os...

  7. VITELLOGENIN GENE TRANSCRIPTION: A RELATIVE QUANTITATIVE EXPOSURE INDICATOR OF ENVIRONMENTAL ESTROGENS

    EPA Science Inventory

    We report the development of a quantifiable exposure indicator for measuring the presence of environmental estrogens in aquatic systems. Synthetic oligonucleotides, designed specifically for the vitellogenin gene (Vg) transcription product, were used in a Reverse Transcription Po...

  8. Green chemistry: reversible nonpolar-to-polar solvent.

    PubMed

    Jessop, Philip G; Heldebrant, David J; Li, Xiaowang; Eckert, Charles A; Liotta, Charles L

    2005-08-25

    Imagine a smart solvent that can be switched reversibly from a liquid with one set of properties to another that has very different properties, upon command. Here we create such a system, in which a non-ionic liquid (an alcohol and an amine base) converts to an ionic liquid (a salt in liquid form) upon exposure to an atmosphere of carbon dioxide, and then reverts back to its non-ionic form when exposed to nitrogen or argon gas. Such switchable solvents should facilitate organic syntheses and separations by eliminating the need to remove and replace solvents after each reaction step. PMID:16121169

  9. Reversible histone methylation regulates brain gene expression and behavior

    PubMed Central

    Xu, Jun; Andreassi, Megan

    2011-01-01

    Epigenetic chromatin remodeling, including reversible histone methylation, regulates gene transcription in brain development and synaptic plasticity. Aberrant chromatin modifications due to mutant chromatin enzymes or chemical exposures have been associated with neurological or psychiatric disorders such as mental retardation, schizophrenia, depression, and drug addiction. Some chromatin enzymes, such as histone demethylases JARID1C and UTX, are coded by X-linked genes which are not X-inactivated in females. The higher expression of JARID1C and UTX in females could contribute to sex differences in brain development and behavior. PMID:20816965

  10. Green chemistry: Reversible nonpolar-to-polar solvent

    NASA Astrophysics Data System (ADS)

    Jessop, Philip G.; Heldebrant, David J.; Li, Xiaowang; Eckert, Charles A.; Liotta, Charles L.

    2005-08-01

    Imagine a smart solvent that can be switched reversibly from a liquid with one set of properties to another that has very different properties, upon command. Here we create such a system, in which a non-ionic liquid (an alcohol and an amine base) converts to an ionic liquid (a salt in liquid form) upon exposure to an atmosphere of carbon dioxide, and then reverts back to its non-ionic form when exposed to nitrogen or argon gas. Such switchable solvents should facilitate organic syntheses and separations by eliminating the need to remove and replace solvents after each reaction step.

  11. Cleaning Our World through Reverse Graffiti

    ERIC Educational Resources Information Center

    Randazzo, Gabe; LaJevic, Lisa

    2013-01-01

    Over the last decade artists have begun to experiment with "reverse pollution" techniques, such as reverse graffiti, which focuses on cleaning environmental surfaces. Having recently been introduced to the works of Moose, the artist known for inventing the reverse graffiti technique, the authors decided to design a curriculum to increase…

  12. Statistical Learning, Letter Reversals, and Reading

    ERIC Educational Resources Information Center

    Treiman, Rebecca; Gordon, Jessica; Boada, Richard; Peterson, Robin L.; Pennington, Bruce F.

    2014-01-01

    Reversal errors play a prominent role in theories of reading disability. We examined reversal errors in the writing of letters by 5- to 6-year-old children. Of the 130 children, 92 had a history of difficulty in producing speech sounds, a risk factor for reading problems. Children were more likely to reverse letter forms that face left, such as…

  13. Categorizing and Promoting Reversibility of Mathematical Concepts

    ERIC Educational Resources Information Center

    Simon, Martin A.; Kara, Melike; Placa, Nicora; Sandir, Hakan

    2016-01-01

    Reversibility of concepts, a key aspect of mathematical development, is often problematic for learners. In this theoretical paper, we present a typology we have developed for categorizing the different reverse concepts that can be related to a particular initial concept and explicate the relationship among these different reverse concepts. We…

  14. Remote Whispering Applying Time Reversal

    SciTech Connect

    Anderson, Brian Eric

    2015-07-16

    The purpose of this project was to explore the use of time reversal technologies as a means for communication to a targeted individual or location. The idea is to have the privacy of whispering in one’s ear, but to do this remotely from loudspeakers not located near the target. Applications of this work include communicating with hostages and survivors in rescue operations, communicating imaging and operational conditions in deep drilling operations, monitoring storage of spent nuclear fuel in storage casks without wires, or clandestine activities requiring signaling between specific points. This technology provides a solution in any application where wires and radio communications are not possible or not desired. It also may be configured to self calibrate on a regular basis to adjust for changing conditions. These communications allow two people to converse with one another in real time, converse in an inaudible frequency range or medium (i.e. using ultrasonic frequencies and/or sending vibrations through a structure), or send information for a system to interpret (even allowing remote control of a system using sound). The time reversal process allows one to focus energy to a specific location in space and to send a clean transmission of a selected signal only to that location. In order for the time reversal process to work, a calibration signal must be obtained. This signal may be obtained experimentally using an impulsive sound, a known chirp signal, or other known signals. It may also be determined from a numerical model of a known environment in which the focusing is desired or from passive listening over time to ambient noise.

  15. Retroviral recombination during reverse transcription.

    PubMed

    Goodrich, D W; Duesberg, P H

    1990-03-01

    After mixed infection, up to half of related retroviruses are recombinants. During infection, retroviral RNA genomes are first converted to complementary DNA (cDNA) and then to double-stranded DNA. Thus recombination could occur during reverse transcription, by RNA template switching, or after reverse transcription, by breakage and reunion of DNA. It has not been possible to distinguish between these two potential mechanisms of recombination because both single-stranded cDNA and double-stranded proviral DNA exist in infected cells during the eclipse period. Therefore we have analyzed for recombinant molecules among cDNA products transcribed in vitro from RNA of disrupted virions. Since recombinants from allelic parents can only be distinguished from parental genomes by point mutations, we have examined the cDNAs from virions with distinct genetic structures for recombinant-specific size and sequence markers. The parents share a common internal allele that allows homology-directed recombination, but each contains specific flanking sequences. One parent is a synthetically altered Harvey murine sarcoma virus RNA that lacks a retroviral 3' terminus but carries a Moloney murine retrovirus-derived envelope gene (env) fragment 3' of its transforming ras gene. The other parent is intact Moloney virus. Using a Harvey-specific 5' primer and a Moloney-specific 3' primer, we have found recombinant cDNAs with the polymerase chain reaction, proving directly that retroviruses can recombine during reverse transcription unassisted by cellular enzymes, probably by template switching during cDNA synthesis. The recombinants that were obtained in vitro were identical with those obtained in parallel experiments in vivo.

  16. Time reversal of water waves.

    PubMed

    Przadka, A; Feat, S; Petitjeans, P; Pagneux, V; Maurel, A; Fink, M

    2012-08-10

    We present time reversal experiments demonstrating refocusing of gravity-capillary waves in a water tank cavity. Owing to the reverberating effect of the cavity, only a few channels are sufficient to reconstruct the surface wave at the point source, even if the absorption is not negligible. Space-time-resolved measurements of the waves during the refocusing allow us to quantitatively demonstrate that the quality of the refocusing increases linearly with the number of reemitting channels. Numerical simulations corresponding to water waves at larger scales, with negligible damping, indicate the possibility of very high quality refocusing.

  17. Reversal Agents for the Direct Oral Anticoagulants.

    PubMed

    Ansell, Jack E

    2016-10-01

    The vitamin K antagonists (VKAs) are associated with a significant rate of major and fatal bleeding complications. The new direct oral anticoagulants (DOACs), even though having a better bleeding profile than the VKAs, are still associated with serious bleeding. The anticoagulation induced by the VKAs can be reversed with both vitamin K and prothrombin complex concentrates, whereas the DOACs were developed without specific reversal agents. Although there is controversy around the necessity of a reversal agent, most clinicians agree that having a reversal agent for the DOACs would be beneficial. Three reversal agents are currently in development. PMID:27637309

  18. Ideal stability limits of reverse shear equilibria

    SciTech Connect

    Phillips, M.W.; Hughes, M.H.

    1996-12-31

    The dependence on various plasma parameters of the ideal stability limit of reverse shear current profiles in TFTR and other tokamaks has been thoroughly explored. Profiles with reverse shear allow core access to the second ballooning stability region. In addition, for sufficient shear reversal, modes with n = 2 and greater are also stabilized. The n = 1 stability threshold is only slightly affected by reverse shear and becomes the limiting instability. The mode is predominately an infernal mode with a significant external contribution. Particular emphasis will be on analysis of recent experimental results of enhanced reverse shear (ERS) profiles in TFTR and a study of those profile characteristics which optimize TFTR performance.

  19. Understanding existing exposure situations.

    PubMed

    Lecomte, J-F

    2016-06-01

    International Commission on Radiological Protection (ICRP) Publication 103 removed the distinction between practices and interventions, and introduced three types of exposure situation: existing, planned, and emergency. It also emphasised the optimisation principle in connection with individual dose restrictions for all controllable exposure situations. Existing exposure situations are those resulting from sources, natural or man-made, that already exist when a decision on control has to be taken. They have common features to be taken into account when implementing general recommendations, such as: the source may be difficult to control; all exposures cannot be anticipated; protective actions can only be implemented after characterisation of the exposure situation; time may be needed to reduce exposure below the reference level; levels of exposure are highly dependent on individual behaviour and present a wide spread of individual dose distribution; exposures at work may be adventitious and not considered as occupational exposure; there is generally no potential for accident; many stakeholders have to be involved; and many factors need to be considered. ICRP is currently developing a series of reports related to the practical implementation of Publication 103 to various existing exposure situations, including exposure from radon, exposure from cosmic radiation in aviation, exposure from processes using naturally occurring radioactive material, and exposure from contaminated sites due to past activities. PMID:26975365

  20. DEMONSTRATION OF HUMAN EXPOSURE TOOLS

    EPA Science Inventory

    The Human Exposure and Atmospheric Sciences Division (HEASD) of the National Exposure Research Laboratory (NERL) conducts research on exposure measurements, human activity patterns, exposure and dose models, and cumulative exposures critical for the Agency to make scientificall...

  1. Reversible subacute ethylene glycol monomethyl ether toxicity associated with microfilm production: a case report

    SciTech Connect

    Cohen, R.

    1984-01-01

    The first reported case of a possible toxic effect of ethylene glycol monomethyl ether (EGME) exposure in the microfilm manufacturing industry is described. Reversible subjective central nervous system complaints and asymptomatic hematopoietic effects occurred following inhalation and skin exposure to EGME. Hematopoietic changes occurred at airborne levels which have been associated with reproductive and teratogenic effects in other studies. This finding leads to a recommendation for further research to determine whether or not hematopoietic medical surveillance can provide an indication of not only EGME hematopoietic effects but also an indication of sufficient EGME exposure to affect human reproduction and fetal development.

  2. Steganography using reversible texture synthesis.

    PubMed

    Wu, Kuo-Chen; Wang, Chung-Ming

    2015-01-01

    We propose a novel approach for steganography using a reversible texture synthesis. A texture synthesis process resamples a smaller texture image, which synthesizes a new texture image with a similar local appearance and an arbitrary size. We weave the texture synthesis process into steganography to conceal secret messages. In contrast to using an existing cover image to hide messages, our algorithm conceals the source texture image and embeds secret messages through the process of texture synthesis. This allows us to extract the secret messages and source texture from a stego synthetic texture. Our approach offers three distinct advantages. First, our scheme offers the embedding capacity that is proportional to the size of the stego texture image. Second, a steganalytic algorithm is not likely to defeat our steganographic approach. Third, the reversible capability inherited from our scheme provides functionality, which allows recovery of the source texture. Experimental results have verified that our proposed algorithm can provide various numbers of embedding capacities, produce a visually plausible texture images, and recover the source texture.

  3. Preference reversal in multiattribute choice.

    PubMed

    Tsetsos, Konstantinos; Usher, Marius; Chater, Nick

    2010-10-01

    A central puzzle for theories of choice is that people's preferences between options can be reversed by the presence of decoy options (that are not chosen) or by the presence of other irrelevant options added to the choice set. Three types of reversal effect reported in the decision-making literature, the attraction, compromise, and similarity effects, have been explained by a number of theoretical proposals. Yet a major theoretical challenge is capturing all 3 effects simultaneously. We review the range of mechanisms that have been proposed to account for decoy effects and analyze in detail 2 computational models, decision field theory (Roe, Busemeyer, & Townsend, 2001) and leaky competing accumulators (Usher & McClelland, 2004), that aim to combine several such mechanisms into an integrated account. By simulating the models, we examine differences in the ways the decoy effects are predicted. We argue that the LCA framework, which follows on Tversky's relational evaluation with loss aversion (Tversky & Kahneman, 1991), provides a more robust account, suggesting that common mechanisms are involved in both high-level decision making and perceptual choice, for which LCA was originally developed.

  4. Differential effect of maternal diet supplementation with α-Linolenic adcid or n-3 long-chain polyunsaturated fatty acids on glial cell phosphatidylethanolamine and phosphatidylserine fatty acid profile in neonate rat brains

    PubMed Central

    2010-01-01

    Background Dietary long-chain polyunsaturated fatty acids (LC-PUFA) are of crucial importance for the development of neural tissues. The aim of this study was to evaluate the impact of a dietary supplementation in n-3 fatty acids in female rats during gestation and lactation on fatty acid pattern in brain glial cells phosphatidylethanolamine (PE) and phosphatidylserine (PS) in the neonates. Methods Sprague-Dawley rats were fed during the whole gestation and lactation period with a diet containing either docosahexaenoic acid (DHA, 0.55%) and eicosapentaenoic acid (EPA, 0.75% of total fatty acids) or α-linolenic acid (ALA, 2.90%). At two weeks of age, gastric content and brain glial cell PE and PS of rat neonates were analyzed for their fatty acid and dimethylacetal (DMA) profile. Data were analyzed by bivariate and multivariate statistics. Results In the neonates from the group fed with n-3 LC-PUFA, the DHA level in gastric content (+65%, P < 0.0001) and brain glial cell PE (+18%, P = 0.0001) and PS (+15%, P = 0.0009) were significantly increased compared to the ALA group. The filtered correlation analysis (P < 0.05) underlined that levels of dihomo-γ-linolenic acid (DGLA), DHA and n-3 docosapentaenoic acid (DPA) were negatively correlated with arachidonic acid (ARA) and n-6 DPA in PE of brain glial cells. No significant correlation between n-3 and n-6 LC-PUFA were found in the PS dataset. DMA level in PE was negatively correlated with n-6 DPA. DMA were found to occur in brain glial cell PS fraction; in this class DMA level was correlated negatively with DHA and positively with ARA. Conclusion The present study confirms that early supplementation of maternal diet with n-3 fatty acids supplied as LC-PUFA is more efficient in increasing n-3 in brain glial cell PE and PS in the neonate than ALA. Negative correlation between n-6 DPA, a conventional marker of DHA deficiency, and DMA in PE suggests n-6 DPA that potentially be considered as a marker of tissue

  5. Light-Induced Reversible Self-Assembly of Gold Nanoparticles Surface-Immobilized with Coumarin Ligands.

    PubMed

    He, Huibin; Feng, Miao; Chen, Qidi; Zhang, Xinqi; Zhan, Hongbing

    2016-01-18

    A novel light-induced reversible self-assembly (LIRSA) system is based on the reversible photodimerization and photocleavage of coumarin groups on the surface of gold nanoparticles (AuNPs) in THF solution. Facilitated by coumarin groups, light irradiation at 365 nm triggers the stable assembly of monodisperse AuNPs; the resulting self-assembly system can be disassembled back to the disassembled state by a relatively short exposure to benign UV light. The reversible self-assembly cycle can be repeated 4 times. A specific concentration range of coumarin ligand and the THF solvent were identified to be the two predominant factors that contribute to the LIRSA of AuNPs. This is the first successful application of reversible photodimerization based on a coumarin derivative in the field of AuNP LIRSA. This LIRSA system may provide unique opportunities for the photoregulated synthesis of many adjustable nanostructures and devices.

  6. CHAPTER ONE: EXPOSURE MEASUREMENTS.

    EPA Science Inventory

    Determining human exposure to suspended particualte concentrations requires measurements that quantify different particle properties in microenvironments where people live, work, and play. Particle mass, size, and chemical composition are important exposure variables, and these ...

  7. EPIDEMIOLOGY AND EXPOSURE ASSESSMENT

    EPA Science Inventory

    Research collaborations between the National Health and Environmental Effects Research Laboratory (NHEERL) and the National Exposure Research Laboratory (NERL) centered on the development and application of exposure analysis tools in environmental epidemiology include the El Paso...

  8. Particle exposures and infections

    EPA Science Inventory

    Particle exposures increase the risk for human infections. Particles can deposit in the nose, pharynx, larynx, trachea, bronchi, and distal lung and, accordingly, the respiratory tract is the system most frequently infected after such exposure; however, meningitis also occurs. Ci...

  9. Limited reversibility of bioconcentration of hydrophobic organic chemicals in phytoplankton.

    PubMed

    Koelmans, Albert A

    2014-07-01

    Aging, reversibility, and desorption rates for the binding of hydrophobic chemicals (HOC) to phytoplankton cells have not been directly measured. Here the effect of bioconcentration time on subsequent desorption of hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs) was studied for the alga Monoraphidium minutum. Cell suspensions were exposed to HCB and PCBs spanning a range of log Kow values of 5.7 to 8.2, for 0.13 to 14 d. Subsequently, reversibility and desorption rates were assessed by extracting the chemicals from the cells using infinite sink extractions with Tenax beads or Empore disks employed in the cell suspension. Uptake was biphasic with constant relative contributions of fast surface sorption. Desorption was biphasic too and well fitted to a first order two compartment model. Increasing exposure times resulted in increasing slowly desorbing chemical fractions and decreased desorption rates from these fractions. For the most hydrophobic PCBs, slowly desorbing fractions were >80-90%, whereas desorption half-lives from these fractions ranged up to 120 days. The slow desorption rates directly prove that bioconcentration to algae can be rate limited and imply that already after a few hours of exposure, HOCs may become practically unavailable for repartitioning. PMID:24915281

  10. Palm reversal errors in native-signing children with autism.

    PubMed

    Shield, Aaron; Meier, Richard P

    2012-01-01

    Children with autism spectrum disorder (ASD) who have native exposure to a sign language such as American Sign Language (ASL) have received almost no scientific attention. This paper reports the first studies on a sample of five native-signing children (four deaf children of deaf parents and one hearing child of deaf parents; ages 4;6 to 7;5) diagnosed with ASD. A domain-general deficit in the ability of children with ASD to replicate the gestures of others is hypothesized to be a source of palm orientation reversal errors in sign. In Study 1, naturalistic language samples were collected from three native-signing children with ASD and were analyzed for errors in handshape, location, movement and palm orientation. In Study 2, four native-signing children with ASD were compared to 12 typically developing deaf children (ages 3;7 to 6;9, all born to deaf parents) on a fingerspelling task. In both studies children with ASD showed a tendency to reverse palm orientation on signs specified for inward/outward orientation. Typically developing deaf children did not produce any such errors in palm orientation. We conclude that this kind of palm reversal has a perceptual rather than a motoric source, and is further evidence of a "self-other mapping" deficit in ASD. PMID:22981637

  11. Palm Reversal Errors in Native-Signing Children with Autism

    PubMed Central

    Shield, Aaron; Meier, Richard P.

    2012-01-01

    Children with autism spectrum disorder (ASD) who have native exposure to a sign language such as American Sign Language (ASL) have received almost no scientific attention. This paper reports the first studies on a sample of five native-signing children (four deaf children of deaf parents and one hearing child of deaf parents; ages 4;6 to 7;5) diagnosed with ASD. A domain-general deficit in the ability of children with ASD to replicate the gestures of others is hypothesized to be a source of palm orientation reversal errors in sign. In Study 1, naturalistic language samples were collected from three native-signing children with ASD and were analyzed for errors in handshape, location, movement and palm orientation. In Study 2, four native-signing children with ASD were compared to 12 typically-developing deaf children (ages 3;7 to 6;9, all born to deaf parents) on a fingerspelling task. In both studies children with ASD showed a tendency to reverse palm orientation on signs specified for inward/outward orientation. Typically-developing deaf children did not produce any such errors in palm orientation. We conclude that this kind of palm reversal has a perceptual rather than a motoric source, and is further evidence of a “self-other mapping” deficit in ASD. PMID:22981637

  12. Reverse polarity shoulder replacement: Current concepts and review of literature

    PubMed Central

    Lee, Ling Hong; Desai, Aravind

    2014-01-01

    Shoulder replacement in cuff tear arthropathy (CTA) is an unsolved challenge. CTA poses a soft tissue deficiency in an arthritic glenohumeral joint which the anatomical total shoulder replacement and hemiarthroplasty cannot reliably provide stability, range of movement, function or satisfactory long term outcome. In the past two decades since the introduction of the reverse shoulder replacement, the prosthesis has evolved and has shown promising results. It is a partially constraint joint by virtue of its design features. The reversal of the concavity and convexity of the joint to the proximal humerus and the glenoid, respectively, also shifts and improves its center of rotation onto the osseous surface of the glenoid with less exposure to shear stress. It is a successful pain relieving procedure, offering good outcome in patients with irreparable massive rotator cuff tear with or without osteoarthritis. Consequently, this has led to wider use and expansion of its indication to include more complex elective and trauma cases. Whereas originally used in the more elderly patients, there is increasingly more demand in the younger patients. It is important to have good quality long term data to support these increasing indications. Therefore, we review the literature on the concepts of reverse shoulder replacement and the contemporary evidence. PMID:25035828

  13. On the reversibility of environmental contamination with persistent organic pollutants.

    PubMed

    Choi, Sung-Deuk; Wania, Frank

    2011-10-15

    An understanding of the factors that control the time trends of persistent organic pollutants (POPs) in the environment is required to evaluate the effectiveness of emission reductions and to predict future exposure. Using a regional contaminant fate model, CoZMo-POP 2, and a generic bell-shaped emission profile, we simulated time trends of hypothetical chemicals with a range of POP-like partitioning and degradation properties in different compartments of a generic warm temperate environment, with the objective of identifying the processes that may prevent the reversibility of environmental contamination with POPs after the end of primary emissions. Evaporation from soil and water can prevent complete reversibility of POP contamination of the atmosphere after the end of emissions. However, under the selected conditions, only for organic chemicals within a narrow range of volatility, that is, a logarithm of the octanol air equilibrium partition coefficient between 7 and 8, and with atmospheric degradation half-lives in excess of a few month can evaporation from environmental reservoirs sustain atmospheric levels that are within an order of magnitude of those resulting from primary emissions. HCB and α-HCH fulfill these criteria, which may explain, why their atmospheric concentrations have remained relatively high decades after their main primary emissions have been largely eliminated. Soil-to-water transfer is found responsible for the lack of reversibility of POP contamination of the aqueous environment after the end of emissions, whereas reversal of water-sediment exchange, although possible, is unlikely to contribute significantly. Differences in the reversibility of contamination in air and water suggests the possibility of changes in the relative importance of various exposure pathways after the end of primary emissions, namely an increase in the importance of the aquatic food chain relative to the agricultural one, especially if the former has a benthic

  14. Reversibly assembled cellular composite materials.

    PubMed

    Cheung, Kenneth C; Gershenfeld, Neil

    2013-09-13

    We introduce composite materials made by reversibly assembling a three-dimensional lattice of mass-produced carbon fiber-reinforced polymer composite parts with integrated mechanical interlocking connections. The resulting cellular composite materials can respond as an elastic solid with an extremely large measured modulus for an ultralight material (12.3 megapascals at a density of 7.2 milligrams per cubic centimeter). These materials offer a hierarchical decomposition in modeling, with bulk properties that can be predicted from component measurements and deformation modes that can be determined by the placement of part types. Because site locations are locally constrained, structures can be produced in a relative assembly process that merges desirable features of fiber composites, cellular materials, and additive manufacturing.

  15. Opioid Antagonist Impedes Exposure.

    ERIC Educational Resources Information Center

    Merluzzi, Thomas V.; And Others

    1991-01-01

    Thirty spider-phobic adults underwent exposure to 17 phobic-related, graded performance tests. Fifteen subjects were assigned to naltrexone, an opioid antagonist, and 15 were assigned to placebo. Naltrexone had a significant effect on exposure, with naltrexone subjects taking significantly longer to complete first 10 steps of exposure and with…

  16. Process of forming compounds using reverse micelle or reverse microemulsion systems

    DOEpatents

    Linehan, John C.; Fulton, John L.; Bean, Roger M.

    1998-01-01

    The present invention is directed to a process for producing a nanometer-sized metal compound. The process comprises forming a reverse micelle or reverse microemulsion system comprising a polar fluid in a non-polar or low-polarity fluid. A first reactant comprising a multi-component, water-soluble metal compound is introduced into the polar fluid in a non-polar or low-polarity fluid. This first reactant can be introduced into the reverse micelle or reverse microemulsion system during formation thereof or subsequent to the formation of the reverse micelle or microemulsion system. The water-soluble metal compound is then reacted in the reverse micelle or reverse microemulsion system to form the nanometer-sized metal compound. The nanometer-sized metal compound is then precipitated from the reverse micelle or reverse microemulsion system.

  17. Effects of acute restraint stress on set-shifting and reversal learning in male rats.

    PubMed

    Thai, Chester A; Zhang, Ying; Howland, John G

    2013-03-01

    Exposure to acute stress alters cognition; however, few studies have examined the effects of acute stress on executive functions such as behavioral flexibility. The goal of the present experiments was to determine the effects of acute periods of stress on two distinct forms of behavioral flexibility: set-shifting and reversal learning. Male Sprague-Dawley rats were trained and tested in an operant-chamber-based task. Some of the rats were exposed to acute restraint stress (30 min) immediately before either the set-shifting test day or the reversal learning test day. Acute stress had no effect on set-shifting, but it significantly facilitated reversal learning, as assessed by both trials to criterion and total errors. In a second experiment, the roles of glucocorticoid (GR) and mineralocorticoid receptors (MR) in the acute-stress-induced facilitation of reversal learning were examined. Systemic administration of the GR-selective antagonist RU38486 (10 mg/kg) or the MR-selective antagonist spironolactone (50 mg/kg) 30 min prior to acute stress failed to block the facilitation on reversal learning. The present results demonstrate a dissociable effect of acute stress on set-shifting and reversal learning and suggest that the facilitation of reversal learning by acute stress may be mediated by factors other than corticosterone.

  18. Periodicity of the earth's magnetic reversals

    NASA Technical Reports Server (NTRS)

    Stothers, R. B.

    1986-01-01

    Results are presented from an attempt to perform a relatively comprehensive analysis of the evidence for a periodicity, with harmonics, of the observed regular reversals of the earth's magnetic field. The database considered covers 296 reversals over the past 165 Myr. Histograms with bins 1 Myr apart reveal only 30 Myr reversal patterns. The reversal dates are fitted to a linear periodic function and a spectrum is computed for the residuals at the adopted dates. The possible presence of multiple periodicities is evaluated and over various time intervals. The analysis shows that a recently observed 15 Myr periodicity is probably a harmonic of the 29.5-30.5 Myr period. The calculations do not confirm an inherent magnetic reversal property of the earth. The reversals may arise from tectonic events or from impacts from extraterrestrial objects.

  19. Neural correlates of response reversal: considering acquisition.

    PubMed

    Budhani, S; Marsh, A A; Pine, D S; Blair, R J R

    2007-02-15

    Previous work on response reversal has typically used a single pair of stimuli that serially reverse. This conflation of acquisition and reversal processes has prevented an examination of the functional role of neural systems implicated in response reversal during acquisition despite the relevance of such data in evaluating accounts of response reversal. In the current study, participants encountered 16 independent reversing stimulus pairs in the context of a probabilistic response reversal paradigm. Functional regions of interest identified as involved in response reversal through a contrast used in the previous literature (punished errors made in the reversal phase versus rewarded correct responses), were interrogated across conditions. Consistent with suggestions that middle frontal cortex codes reward, this region showed significantly greater responses to rewarded rather than punished trials irrespective of accuracy or learning phase (acquisition or reversal). Consistent with the suggestion that this coding of the expectation of reinforcement is acquired via input from the amygdala, we observed significant positive connectivity between activity within the amygdala and a region of rostral anterior cingulate cortex highly proximal to this region of middle frontal/mesial prefrontal cortex. In contrast, inferior frontal cortex, anterior cingulate cortex and caudate showed greater responses to punished errors than to the rewarded correct responses. These three regions also showed significant activation to rewarded errors during acquisition, in contrast to positions suggesting that inferior frontal cortex represents punishment or suppresses previously rewarded responses. Moreover, a connectivity analysis with an anterior cingulate cortex seed revealed highly significant positive connectivity among them. The implications of these data for recent accounts of response reversal and of response reversal impairments in specific neuropsychiatric populations are discussed.

  20. Gravity controlled anti-reverse rotation device

    DOEpatents

    Dickinson, Robert J.; Wetherill, Todd M.

    1983-01-01

    A gravity assisted anti-reverse rotation device for preventing reverse rotation of pumps and the like. A horizontally mounted pawl is disposed to mesh with a fixed ratchet preventing reverse rotation when the pawl is advanced into intercourse with the ratchet by a vertically mounted lever having a lumped mass. Gravitation action on the lumped mass urges the pawl into mesh with the ratchet, while centrifugal force on the lumped mass during forward, allowed rotation retracts the pawl away from the ratchet.

  1. Serial reversal learning in bumblebees (Bombus impatiens).

    PubMed

    Strang, Caroline G; Sherry, David F

    2014-05-01

    Bumblebees are capable of rapidly learning discriminations, but flexibility in bumblebee learning is less well understood. We tested bumblebees (Bombus impatiens) on a serial reversal learning task. A serial reversal task requires learning of an initial discrimination between two differentially rewarded stimuli, followed by multiple reversals of the reward contingency between stimuli. A reduction in errors with repeated reversals in a serial reversal task is an indicator of behavioural flexibility. Bees were housed in a large indoor environment and tested during foraging flights. Testing free-flying bees allowed for large numbers of trials and reversals. All bees were trained to perform a simultaneous discrimination between two colours for a nectar reward, followed by nine reversals of this discrimination. Results showed that bumblebees reduced errors and improved their performance across successive reversals. A reduction in perseverative errors was the major cause of the improvement in performance. Bees showed a slight increase in error rate in their final trials, perhaps as a consequence of increasing proactive interference, but proactive interference may also have contributed to the overall improvement in performance across reversals. Bumblebees are thus capable of behavioural flexibility comparable to that of other animals and may use proactive interference as a mechanism of behavioural flexibility in varying environments.

  2. Exposures to lead.

    PubMed

    Callan, Anna C; Hinwood, Andrea L

    2011-01-01

    The Pacific Basin Consortium for Environment and Health hosted a workshop on Exposures to Lead. Speakers from Australia and the United States of America addressed current research knowledge on lead exposures and health effects in children, risk assessment and communication issues in dealing with lead exposure sources, different methods for assessing exposure, and the variety of scenarios where lead still remains a pollutant of concern. Mining continues to be a source of lead for many communities, and approaches to reducing exposures in these settings present particular challenges. A Perth Declaration for the Global Reduction of Childhood Lead Exposure was signed by participants of the meeting and is aimed at increasing attention to the need to continue to assess lead in the environment and to develop strategies to reduce lead in the environment and exposure by communities. PMID:21714377

  3. Exposures to lead.

    PubMed

    Callan, Anna C; Hinwood, Andrea L

    2011-01-01

    The Pacific Basin Consortium for Environment and Health hosted a workshop on Exposures to Lead. Speakers from Australia and the United States of America addressed current research knowledge on lead exposures and health effects in children, risk assessment and communication issues in dealing with lead exposure sources, different methods for assessing exposure, and the variety of scenarios where lead still remains a pollutant of concern. Mining continues to be a source of lead for many communities, and approaches to reducing exposures in these settings present particular challenges. A Perth Declaration for the Global Reduction of Childhood Lead Exposure was signed by participants of the meeting and is aimed at increasing attention to the need to continue to assess lead in the environment and to develop strategies to reduce lead in the environment and exposure by communities.

  4. High Performance Field Reversed Configurations

    NASA Astrophysics Data System (ADS)

    Binderbauer, Michl

    2014-10-01

    The field-reversed configuration (FRC) is a prolate compact toroid with poloidal magnetic fields. FRCs could lead to economic fusion reactors with high power density, simple geometry, natural divertor, ease of translation, and possibly capable of burning aneutronic fuels. However, as in other high-beta plasmas, there are stability and confinement concerns. These concerns can be addressed by introducing and maintaining a significant fast ion population in the system. This is the approach adopted by TAE and implemented for the first time in the C-2 device. Studying the physics of FRCs driven by Neutral Beam (NB) injection, significant improvements were made in confinement and stability. Early C-2 discharges had relatively good confinement, but global power losses exceeded the available NB input power. The addition of axially streaming plasma guns, magnetic end plugs as well as advanced surface conditioning leads to dramatic reductions in turbulence driven losses and greatly improved stability. As a result, fast ion confinement significantly improved and allowed for build-up of a dominant fast particle population. Under such appropriate conditions we achieved highly reproducible, long-lived, macroscopically stable FRCs with record lifetimes. This demonstrated many beneficial effects of large orbit particles and their performance impact on FRCs Together these achievements point to the prospect of beam-driven FRCs as a path toward fusion reactors. This presentation will review and expand on key results and present context for their interpretation.

  5. Reverse Engineering Adverse Outcome Pathways

    SciTech Connect

    Perkins, Edward; Chipman, J.K.; Edwards, Stephen; Habib, Tanwir; Falciani, Francesco; Taylor, Ronald C.; Van Aggelen, Graham; Vulpe, Chris; Antczak, Philipp; Loguinov, Alexandre

    2011-01-30

    The toxicological effects of many stressors are mediated through unknown, or poorly characterized, mechanisms of action. We describe the application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, metabolic, signaling) to characterize adverse outcome pathways (AOPs) for chemicals that disrupt the hypothalamus-pituitary-gonadal endocrine axis in fathead minnows. Gene expression changes in fathead minnow ovaries in response to 7 different chemicals, over different times, doses, and in vivo versus in vitro conditions were captured in a large data set of 868 arrays. We examined potential AOPs of the antiandrogen flutamide using two mutual information theory methods, ARACNE and CLR to infer gene regulatory networks and potential adverse outcome pathways. Representative networks from these studies were used to predict a network path from stressor to adverse outcome as a candidate AOP. The relationship of individual chemicals to an adverse outcome can be determined by following perturbations through the network in response to chemical treatment leading to the nodes associated with the adverse outcome. Identification of candidate pathways allows for formation of testable hypotheses about key biologic processes, biomarkers or alternative endpoints, which could be used to monitor an adverse outcome pathway. Finally, we identify the unique challenges facing the application of this approach in ecotoxicology, and attempt to provide a road map for the utilization of these tools. Key Words: mechanism of action, toxicology, microarray, network inference

  6. Reversing expectations during discourse comprehension

    PubMed Central

    Xiang, Ming; Kuperberg, Gina

    2014-01-01

    In two ERP experiments, we asked whether comprehenders used the concessive connective, even so, to predict upcoming events. Participants read coherent and incoherent scenarios, with and without even so, e.g. “Elizabeth had a history exam on Monday. She took the test and aced/failed it. (Even so), she went home and celebrated wildly.”, as they rated coherence (Experiment 1) or simply answered intermittent comprehension questions (Experiment 2). The semantic function of even so was used to reverse real-world knowledge predictions, leading to an attenuated N400 to coherent versus incoherent target words (“celebrated”). Moreover, its pragmatic communicative function enhanced predictive processing, leading to more N400 attenuation to coherent targets in scenarios with than without even so. This benefit however, did not come for free: the detection of failed event predictions triggered a later posterior positivity and/or an anterior negativity effect, and costs of maintaining alternative likelihood relations manifest as a sustained negativity effect on sentence-final words. PMID:25914891

  7. Entropic uncertainty and measurement reversibility

    NASA Astrophysics Data System (ADS)

    Berta, Mario; Wehner, Stephanie; Wilde, Mark M.

    2016-07-01

    The entropic uncertainty relation with quantum side information (EUR-QSI) from (Berta et al 2010 Nat. Phys. 6 659) is a unifying principle relating two distinctive features of quantum mechanics: quantum uncertainty due to measurement incompatibility, and entanglement. In these relations, quantum uncertainty takes the form of preparation uncertainty where one of two incompatible measurements is applied. In particular, the ‘uncertainty witness’ lower bound in the EUR-QSI is not a function of a post-measurement state. An insightful proof of the EUR-QSI from (Coles et al 2012 Phys. Rev. Lett. 108 210405) makes use of a fundamental mathematical consequence of the postulates of quantum mechanics known as the non-increase of quantum relative entropy under quantum channels. Here, we exploit this perspective to establish a tightening of the EUR-QSI which adds a new state-dependent term in the lower bound, related to how well one can reverse the action of a quantum measurement. As such, this new term is a direct function of the post-measurement state and can be thought of as quantifying how much disturbance a given measurement causes. Our result thus quantitatively unifies this feature of quantum mechanics with the others mentioned above. We have experimentally tested our theoretical predictions on the IBM quantum experience and find reasonable agreement between our predictions and experimental outcomes.

  8. Reverse Genetics in Ecological Research

    PubMed Central

    Schwachtje, Jens; Kutschbach, Susan; Baldwin, Ian T.

    2008-01-01

    By precisely manipulating the expression of individual genetic elements thought to be important for ecological performance, reverse genetics has the potential to revolutionize plant ecology. However, untested concerns about possible side-effects of the transformation technique, caused by Agrobacterium infection and tissue culture, on plant performance have stymied research by requiring onerous sample sizes. We compare 5 independently transformed Nicotiana attenuata lines harboring empty vector control (EVC) T-DNA lacking silencing information with isogenic wild types (WT), and measured a battery of ecologically relevant traits, known to be important in plant-herbivore interactions: phytohormones, secondary metabolites, growth and fitness parameters under stringent competitive conditions, and transcriptional regulation with microarrays. As a positive control, we included a line silenced in trypsin proteinase inhibitor gene (TPI) expression, a potent anti-herbivore defense known to exact fitness costs in its expression, in the analysis. The experiment was conducted twice, with 10 and 20 biological replicates per genotype. For all parameters, we detected no difference between any EVC and WT lines, but could readily detect a fitness benefit of silencing TPI production. A statistical power analyses revealed that the minimum sample sizes required for detecting significant fitness differences between EVC and WT was 2–3 orders of magnitude larger than the 10 replicates required to detect a fitness effect of TPI silencing. We conclude that possible side-effects of transformation are far too low to obfuscate the study of ecologically relevant phenotypes. PMID:18253491

  9. Differential effects of cocaine exposure on the abundance of phospholipid species in rat brain and blood*

    PubMed Central

    Cummings, Brian S.; Pati, Sumitra; Sahin, Serap; Scholpa, Natalie E.; Monian, Prashant; Trinquero, Paul O.; Clark, Jason K.; Wagner, John J.

    2015-01-01

    Background Lipid profiles in the blood are altered in human cocaine users, suggesting that cocaine-exposure can induce lipid remodeling. Methods Cocaine-induced locomotor sensitization in rats was followed by shotgun lipidomics using electrospray ionization-mass spectrometry (ESI-MS) and determined changes in brain tissues. To determine if any lipidomic changes were also reflected in the blood, we performed principal component analysis (PCA) of lipidomic spectra isolated from cocaine-treated animals. Alterations in the abundance of phospholipid species were correlated with behavioral changes in the magnitude of either the initial response to drug or locomotor sensitization. Results Behavioral sensitization altered the relative abundance of several phospholipid species in the hippocampus and cerebellum, measured one week following the final exposure to cocaine. In contrast, relatively few effects on phospholipids in either the dorsal or the ventral striatum were observed. PCA analysis demonstrated that cocaine altered the relative abundance of several glycerophospholipid species as compared to saline-injected controls. Subsequent MS/MS analysis identified some of these lipids as phosphatidylethanolamines, phosphatidylserines and phosphatidylcholines. The relative abundance of some of these phospholipid species were well correlated (R2 of 0.7 or higher) with either the initial response to cocaine or locomotor sensitization. Conclusion Taken together, these data demonstrate that a cocaine-conditioning experience results in the remodeling of specific phospholipids in rat brain tissue in a region-specific manner and also alters the intensities and types of phospholipid species in rat blood. These results further suggest that such changes may serve as biomarkers to assess the neuroadaptations occurring following repeated exposure to cocaine. PMID:25960140

  10. Alteration of the aPA ELISA by UV exposure of polystyrene microtiter plates.

    PubMed

    Goldberg, J S; Wagenknecht, D R; McIntyre, J A

    1996-01-01

    Interlaboratory inconsistencies in antiphospholipid antibody (aPA) solid phase assays have prompted controversy in clinical laboratory testing for aPA. We found that the aPA ELISA can be influenced by the type of microtiter plate utilized and by the conditions in which the plates are stored. By exposing 96-well, flat-bottom polystyrene microtiter plates to short wave UV light (254 nm), the aPA ELISA signal decreased in a UV dose-dependent manner. No effect was seen with long wave UV light (366 nm). These results were independent of the antibody isotype under study or the phospholipid (PL) antigen used: anionic phosphatidylserine (PS) and cardiolipin (CL), or zwitterionic phosphatidylethanolamine (PE). Purified human beta 2-glycoprotein I (beta 2 GPI), a known cofactor for anionic PL, and rabbit anti-beta 2 GPI antisera were used to demonstrate that beta 2 GPI bound equally to UV treated and untreated microtiter plates. In contrast, recognition of beta 2 GPI on an anionic PL surface was decreased on UV treated plates, suggesting that UV exposure alters the lipid binding properties of the microliter plate. To determine whether UV exposure inhibited PL binding directly or caused a change in the way the PL was bound, the amount of PL bound to UV treated and untreated plates was measured by using fluorescent labeled PS and a fluorimeter. PS binding was decreased by 53% in UV treated wells as compared to untreated wells. These data show that short wave UV exposure reduces PL binding to polystyrene microtiter plates, thereby reducing the amount of beta 2 GPI bound to PL coated ELISA plates. Thus by using UV exposed microtiter plates, decreased or false-negative a PA ELISA results may be obtained for aPA positive plasmas. PMID:8887002

  11. Reversal of colchicine-induced mitotic arrest in Chinese hamster cells with a colchicine-specific monoclonal antibody.

    PubMed

    Rouan, S K; Otterness, I G; Cunningham, A C; Holden, H E; Rhodes, C T

    1990-10-01

    The ability of a high-affinity colchicine-binding monoclonal antibody to reverse the effects of colchicine on Chinese hamster ovary cells was investigated. Using flow cytometry, a complete mitotic blockade was demonstrated after 16 hours with 2.5 x 10(-7) mol/l (molar) colchicine. Colchicine-induced changes were reversible when equimolar antibody was added simultaneously with or up to 6 hours after colchicine. With further delay in addition of antibody, a progressive irreversible increase in mitotic blockade and increase in mean cell size was observed. Prolonged colchicine exposure, without antibody reversal, led to polyploidy and structural chromosome breakage. Early antibody reversal restored cells to the diploid state, whereas delayed reversal resulted in a time-dependent increase in polyploidy. Colchicine-induced polyploidy and chromosomal aberrations may be the basis for both colchicine toxicity and the time-dependent increase in irreversibility of colchicine effects.

  12. Large reverse saturable absorption under weak continuous incoherent light.

    PubMed

    Hirata, Shuzo; Totani, Kenro; Yamashita, Takashi; Adachi, Chihaya; Vacha, Martin

    2014-10-01

    In materials showing reverse saturable absorption (RSA), the optical absorbance increases as the power of the light incident on them increases. To date, RSA has only been observed when very intense light sources, such as short-pulse lasers, are used. Here, we show that hydroxyl steroidal matrices embedding properly designed aromatic molecules as acceptors and transition-metal complexes as donors exhibit high RSA on exposure to weak incoherent light at room temperature and in air. Accumulation by photosensitization of long-lived room-temperature triplet excitons in acceptors with a large triplet-triplet absorption coefficient allows a nonlinear increase in absorbance also under low-power irradiation conditions. As a consequence, continuous exposure to weak light significantly decreases the transmittance of thin films fabricated with these compounds. These optical limiting properties may be used to protect eyes and light sensors from exposure to intense radiation generated by incoherent sources and for other light-absorption applications that have not been realized with conventional RSA materials.

  13. Large reverse saturable absorption under weak continuous incoherent light

    NASA Astrophysics Data System (ADS)

    Hirata, Shuzo; Totani, Kenro; Yamashita, Takashi; Adachi, Chihaya; Vacha, Martin

    2014-10-01

    In materials showing reverse saturable absorption (RSA), the optical absorbance increases as the power of the light incident on them increases. To date, RSA has only been observed when very intense light sources, such as short-pulse lasers, are used. Here, we show that hydroxyl steroidal matrices embedding properly designed aromatic molecules as acceptors and transition-metal complexes as donors exhibit high RSA on exposure to weak incoherent light at room temperature and in air. Accumulation by photosensitization of long-lived room-temperature triplet excitons in acceptors with a large triplet-triplet absorption coefficient allows a nonlinear increase in absorbance also under low-power irradiation conditions. As a consequence, continuous exposure to weak light significantly decreases the transmittance of thin films fabricated with these compounds. These optical limiting properties may be used to protect eyes and light sensors from exposure to intense radiation generated by incoherent sources and for other light-absorption applications that have not been realized with conventional RSA materials.

  14. Reversible response to NO of copper phthalocyanine-based sensor at low temperature

    SciTech Connect

    Emelyanov, Yu.L.; Khatko, V.V.; Tomchenko, A.A.

    1996-12-31

    Recently, it have been reported that the NO{sub x} adsorption resulted in marked in the semiconducting properties of copper tetra-tert-butyl phthalocyanine Langmuir-Blodgett films (CuTTBPc LB films). However, the recovery time of these chemiresistors after NO{sub x} exposure was very long at room temperature. Because of this, the heating up to 150{degrees}C was needed for reasons of a reversibility. In the present paper, the authors report on the development of CuTTBPc-based sensor reversibly operating at low temperature (<50{degrees}C).

  15. Effect of sequential isoproturon pulse exposure on Scenedesmus vacuolatus.

    PubMed

    Vallotton, Nathalie; Eggen, Rik Ilda Lambertus; Chèvre, Nathalie

    2009-04-01

    Aquatic organisms are typically exposed to fluctuating concentrations of herbicides in streams. To assess the effects on algae of repeated peak exposure to the herbicide isoproturon, we subjected the alga Scenedesmus vacuolatus to two sequential pulse exposure scenarios. Effects on growth and on the inhibition of the effective quantum yield of photosystem II (PSII) were measured. In the first scenario, algae were exposed to short, 5-h pulses at high isoproturon concentrations (400 and 1000 microg/l), each followed by a recovery period of 18 h, while the second scenario consisted of 22.5-h pulses at lower concentrations (60 and 120 microg/l), alternating with short recovery periods (1.5 h). In addition, any changes in the sensitivity of the algae to isoproturon following sequential pulses were examined by determining the growth rate-EC(50) prior to and following exposure. In both exposure scenarios, we found that algal growth and its effective quantum yield were systematically inhibited during the exposures and that these effects were reversible. Sequential pulses to isoproturon could be considered a sequence of independent events. Nevertheless, a consequence of inhibited growth during the repeated exposures is the cumulative decrease in biomass production. Furthermore, in the second scenario, when the sequence of long pulses began to approach a scenario of continuous exposure, a slight increase in the tolerance of the algae to isoproturon was observed. These findings indicated that sequential pulses do affect algae during each pulse exposure, even if algae recover between the exposures. These observations could support an improved risk assessment of fluctuating exposures to reversibly acting herbicides. PMID:18709397

  16. 14 CFR 25.933 - Reversing systems.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... reversal in flight the engine will produce no more than flight idle thrust. In addition, it must be shown by analysis or test, or both, that— (i) Each operable reverser can be restored to the forward thrust position; and (ii) The airplane is capable of continued safe flight and landing under any possible...

  17. 14 CFR 25.933 - Reversing systems.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... reversal in flight the engine will produce no more than flight idle thrust. In addition, it must be shown by analysis or test, or both, that— (i) Each operable reverser can be restored to the forward thrust position; and (ii) The airplane is capable of continued safe flight and landing under any possible...

  18. 14 CFR 25.933 - Reversing systems.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... reversal in flight the engine will produce no more than flight idle thrust. In addition, it must be shown by analysis or test, or both, that— (i) Each operable reverser can be restored to the forward thrust position; and (ii) The airplane is capable of continued safe flight and landing under any possible...

  19. 14 CFR 25.933 - Reversing systems.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... reversal in flight the engine will produce no more than flight idle thrust. In addition, it must be shown by analysis or test, or both, that— (i) Each operable reverser can be restored to the forward thrust position; and (ii) The airplane is capable of continued safe flight and landing under any possible...

  20. 14 CFR 25.933 - Reversing systems.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... reversal in flight the engine will produce no more than flight idle thrust. In addition, it must be shown by analysis or test, or both, that— (i) Each operable reverser can be restored to the forward thrust position; and (ii) The airplane is capable of continued safe flight and landing under any possible...

  1. The Rate Laws for Reversible Reactions.

    ERIC Educational Resources Information Center

    King, Edward L.

    1986-01-01

    Provides background information for teachers on the rate laws for reversible reactions. Indicates that although prediction of the form of the rate law for a reverse reaction given the rate law for the forward reaction is not certain, the number of possibilities is limited because of relationships described. (JN)

  2. Empirical Evidence for Reversibility by Inversion

    ERIC Educational Resources Information Center

    Gladstone, Roy; Palazzo, Richard

    1974-01-01

    This study demonstrates that, given the assumption that the child does have some understanding of both height and amount, many nonconservers do give correct reversal judgments for both. Also, reversibility data from this study do not support the theory that a new stage appears when water conservation judgments appear. (Author/ED)

  3. Neuronal Activation for Semantically Reversible Sentences

    ERIC Educational Resources Information Center

    Richardson, Fiona M.; Thomas, Michael S. C.; Price, Cathy J.

    2010-01-01

    Semantically reversible sentences are prone to misinterpretation and take longer for typically developing children and adults to comprehend; they are also particularly problematic for those with language difficulties such as aphasia or Specific Language Impairment. In our study, we used fMRI to compare the processing of semantically reversible and…

  4. 14 CFR 23.933 - Reversing systems.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... testing, or both, for propeller systems that allow the propeller blades to move from the flight low-pitch... systems. (a) For turbojet and turbofan reversing systems. (1) Each system intended for ground operation only must be designed so that, during any reversal in flight, the engine will produce no more...

  5. 14 CFR 23.933 - Reversing systems.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... testing, or both, for propeller systems that allow the propeller blades to move from the flight low-pitch... systems. (a) For turbojet and turbofan reversing systems. (1) Each system intended for ground operation only must be designed so that, during any reversal in flight, the engine will produce no more...

  6. 14 CFR 23.933 - Reversing systems.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... testing, or both, for propeller systems that allow the propeller blades to move from the flight low-pitch... systems. (a) For turbojet and turbofan reversing systems. (1) Each system intended for ground operation only must be designed so that, during any reversal in flight, the engine will produce no more...

  7. 14 CFR 23.933 - Reversing systems.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... testing, or both, for propeller systems that allow the propeller blades to move from the flight low-pitch... systems. (a) For turbojet and turbofan reversing systems. (1) Each system intended for ground operation only must be designed so that, during any reversal in flight, the engine will produce no more...

  8. Reversible logic gates on Physarum Polycephalum

    SciTech Connect

    Schumann, Andrew

    2015-03-10

    In this paper, we consider possibilities how to implement asynchronous sequential logic gates and quantum-style reversible logic gates on Physarum polycephalum motions. We show that in asynchronous sequential logic gates we can erase information because of uncertainty in the direction of plasmodium propagation. Therefore quantum-style reversible logic gates are more preferable for designing logic circuits on Physarum polycephalum.

  9. Nonidentified Kikuchi lines with reverse contrast

    NASA Astrophysics Data System (ADS)

    Karakhanyan, K. R.

    2009-03-01

    Electron diffraction patterns of silicon in transmission with contrast reversal from bright to dark for an unidentified Kikuchi line along its length have been obtained. The contrast reversal of an unidentified line is explained within the elementary mechanism of Kikuchi pattern formation taking into account the Kikuchi electron double diffraction.

  10. The New Reverse Transfer: A National Landscape

    ERIC Educational Resources Information Center

    Friedel, Janice Nahra; Wilson, Sarah L.

    2015-01-01

    For decades, higher education professionals and researchers have used the term reverse transfer to describe a specific group of students. A current review of community college literature and higher education policy reflects a contextual change of the term, and today reverse transfer has grown to include students who transfer from a two-year…

  11. Reverse Transfer Students: Characteristics, Motivations, and Implications

    ERIC Educational Resources Information Center

    Lowrey, Kathryn Elizabeth

    2010-01-01

    The reverse transfer literature contains studies investigating the demographic characteristics of postsecondary students that attended a community college after attending a four-year institution, and their proportion in the community college student population. A few researchers have investigated reverse transfer student motives for enrolling in…

  12. Potential Adverse Effects of Prolonged Sevoflurane Exposure on Developing Monkey Brain: From Abnormal Lipid Metabolism to Neuronal Damage.

    PubMed

    Liu, Fang; Rainosek, Shuo W; Frisch-Daiello, Jessica L; Patterson, Tucker A; Paule, Merle G; Slikker, William; Wang, Cheng; Han, Xianlin

    2015-10-01

    Sevoflurane is a volatile anesthetic that has been widely used in general anesthesia, yet its safety in pediatric use is a public concern. This study sought to evaluate whether prolonged exposure of infant monkeys to a clinically relevant concentration of sevoflurane is associated with any adverse effects on the developing brain. Infant monkeys were exposed to 2.5% sevoflurane for 9 h, and frontal cortical tissues were harvested for DNA microarray, lipidomics, Luminex protein, and histological assays. DNA microarray analysis showed that sevoflurane exposure resulted in a broad identification of differentially expressed genes (DEGs) in the monkey brain. In general, these genes were associated with nervous system development, function, and neural cell viability. Notably, a number of DEGs were closely related to lipid metabolism. Lipidomic analysis demonstrated that critical lipid components, (eg, phosphatidylethanolamine, phosphatidylserine, and phosphatidylglycerol) were significantly downregulated by prolonged exposure of sevoflurane. Luminex protein analysis indicated abnormal levels of cytokines in sevoflurane-exposed brains. Consistently, Fluoro-Jade C staining revealed more degenerating neurons after sevoflurane exposure. These data demonstrate that a clinically relevant concentration of sevoflurane (2.5%) is capable of inducing and maintaining an effective surgical plane of anesthesia in the developing nonhuman primate and that a prolonged exposure of 9 h resulted in profound changes in gene expression, cytokine levels, lipid metabolism, and subsequently, neuronal damage. Generally, sevoflurane-induced neuronal damage was also associated with changes in lipid content, composition, or both; and specific lipid changes could provide insights into the molecular mechanism(s) underlying anesthetic-induced neurotoxicity and may be sensitive biomarkers for the early detection of anesthetic-induced neuronal damage.

  13. Orthographic similarity: the case of "reversed anagrams".

    PubMed

    Morris, Alison L; Still, Mary L

    2012-07-01

    How orthographically similar are words such as paws and swap, flow and wolf, or live and evil? According to the letter position coding schemes used in models of visual word recognition, these reversed anagrams are considered to be less similar than words that share letters in the same absolute or relative positions (such as home and hose or plan and lane). Therefore, reversed anagrams should not produce the standard orthographic similarity effects found using substitution neighbors (e.g., home, hose). Simulations using the spatial coding model (Davis, Psychological Review 117, 713-758, 2010), for example, predict an inhibitory masked-priming effect for substitution neighbor word pairs but a null effect for reversed anagrams. Nevertheless, we obtained significant inhibitory priming using both stimulus types (Experiment 1). We also demonstrated that robust repetition blindness can be obtained for reversed anagrams (Experiment 2). Reversed anagrams therefore provide a new test for models of visual word recognition and orthographic similarity.

  14. Three component vibrational time reversal communication

    DOE PAGESBeta

    Anderson, Brian E.; Ulrich, Timothy J.; Ten Cate, James A.

    2015-01-01

    Time reversal provides an optimal prefilter matched signal to apply to a communication signal before signal transmission. Time reversal allows compensation for wave speed dispersion and can function well in reverberant environments. Time reversal can be used to focus elastic energy to each of the three components of motion independently. A pipe encased in concrete was used to demonstrate the ability to conduct communications of information using three component time reversal. Furthermore, the ability of time reversal to compensate for multi-path distortion (overcoming reverberation) will be demonstrated and the rate of signal communication will be presented. [The U.S. Department ofmore » Energy, through the LANL/LDRD Program, is gratefully acknowledged for supporting this work.]« less

  15. Improving the Convergence of Reversible Samplers

    NASA Astrophysics Data System (ADS)

    Rey-Bellet, Luc; Spiliopoulos, Konstantinos

    2016-08-01

    In Monte-Carlo methods the Markov processes used to sample a given target distribution usually satisfy detailed balance, i.e. they are time-reversible. However, relatively recent results have demonstrated that appropriate reversible and irreversible perturbations can accelerate convergence to equilibrium. In this paper we present some general design principles which apply to general Markov processes. Working with the generator of Markov processes, we prove that for some of the most commonly used performance criteria, i.e., spectral gap, asymptotic variance and large deviation functionals, sampling is improved for appropriate reversible and irreversible perturbations of some initially given reversible sampler. Moreover we provide specific constructions for such reversible and irreversible perturbations for various commonly used Markov processes, such as Markov chains and diffusions. In the case of diffusions, we make the discussion more specific using the large deviations rate function as a measure of performance.

  16. Parkinson’s disease managing reversible neurodegeneration

    PubMed Central

    Hinz, Marty; Stein, Alvin; Cole, Ted; McDougall, Beth; Westaway, Mark

    2016-01-01

    Traditionally, the Parkinson’s disease (PD) symptom course has been classified as an irreversible progressive neurodegenerative disease. This paper documents 29 PD and treatment-induced systemic depletion etiologies which cause and/or exacerbate the seven novel primary relative nutritional deficiencies associated with PD. These reversible relative nutritional deficiencies (RNDs) may facilitate and accelerate irreversible progressive neurodegeneration, while other reversible RNDs may induce previously undocumented reversible pseudo-neurodegeneration that is hiding in plain sight since the symptoms are identical to the symptoms being experienced by the PD patient. Documented herein is a novel nutritional approach for reversible processes management which may slow or halt irreversible progressive neurodegenerative disease and correct reversible RNDs whose symptoms are identical to the patient’s PD symptoms. PMID:27103805

  17. Estimation and uncertainty of reversible Markov models.

    PubMed

    Trendelkamp-Schroer, Benjamin; Wu, Hao; Paul, Fabian; Noé, Frank

    2015-11-01

    Reversibility is a key concept in Markov models and master-equation models of molecular kinetics. The analysis and interpretation of the transition matrix encoding the kinetic properties of the model rely heavily on the reversibility property. The estimation of a reversible transition matrix from simulation data is, therefore, crucial to the successful application of the previously developed theory. In this work, we discuss methods for the maximum likelihood estimation of transition matrices from finite simulation data and present a new algorithm for the estimation if reversibility with respect to a given stationary vector is desired. We also develop new methods for the Bayesian posterior inference of reversible transition matrices with and without given stationary vector taking into account the need for a suitable prior distribution preserving the meta-stable features of the observed process during posterior inference. All algorithms here are implemented in the PyEMMA software--http://pyemma.org--as of version 2.0. PMID:26547152

  18. Three component vibrational time reversal communication

    SciTech Connect

    Anderson, Brian E.; Ulrich, Timothy J.; Ten Cate, James A.

    2015-01-01

    Time reversal provides an optimal prefilter matched signal to apply to a communication signal before signal transmission. Time reversal allows compensation for wave speed dispersion and can function well in reverberant environments. Time reversal can be used to focus elastic energy to each of the three components of motion independently. A pipe encased in concrete was used to demonstrate the ability to conduct communications of information using three component time reversal. Furthermore, the ability of time reversal to compensate for multi-path distortion (overcoming reverberation) will be demonstrated and the rate of signal communication will be presented. [The U.S. Department of Energy, through the LANL/LDRD Program, is gratefully acknowledged for supporting this work.

  19. Estimation and uncertainty of reversible Markov models

    NASA Astrophysics Data System (ADS)

    Trendelkamp-Schroer, Benjamin; Wu, Hao; Paul, Fabian; Noé, Frank

    2015-11-01

    Reversibility is a key concept in Markov models and master-equation models of molecular kinetics. The analysis and interpretation of the transition matrix encoding the kinetic properties of the model rely heavily on the reversibility property. The estimation of a reversible transition matrix from simulation data is, therefore, crucial to the successful application of the previously developed theory. In this work, we discuss methods for the maximum likelihood estimation of transition matrices from finite simulation data and present a new algorithm for the estimation if reversibility with respect to a given stationary vector is desired. We also develop new methods for the Bayesian posterior inference of reversible transition matrices with and without given stationary vector taking into account the need for a suitable prior distribution preserving the meta-stable features of the observed process during posterior inference. All algorithms here are implemented in the PyEMMA software — http://pyemma.org — as of version 2.0.

  20. Genome exposure and regulation in mammalian cells.

    PubMed

    Puck, T T; Webb, P; Johnson, R

    1998-09-01

    A method of measurement of exposed DNA (i.e. hypersensitive to DNase I hydrolysis) as opposed to sequestered (hydrolysis resistant) DNA in isolated nuclei of mammalian cells is described. While cell cultures exhibit some differences in behavior from day to day, the general pattern of exposed and sequestered DNA is satisfactorily reproducible and agrees with results previously obtained by other methods. The general pattern of DNA hydrolysis exhibited by all cells tested consists of a curve which at first rises sharply with increasing DNase I, and then becomes almost horizontal, indicating that roughly about half of the nuclear DNA is highly sequestered. In 4 cases where transformed cells (Raszip6, CHO, HL60 and PC12) were compared, each with its more normal homolog (3T3, and the reverse transformed versions of CHO, HL60 and PC12, achieved by dibutyryl cyclic AMP [DBcAMP], retinoic acid, and nerve growth factor [NGF] respectively), the transformed form displayed less genome exposure than the nontransformed form at every DNase I dose tested. When Ca++ was excluded from the hydrolysis medium in both the Raszip6-3T3 and the CHO-DBcAMP systems, the normal cell forms lost their increased exposure reverting to that of the transformed forms. Therefore Ca++ appears necessary for maintenance of the DNA in the more highly exposed state characteristic of the nontransformed phenotype. LiCl increases the DNA exposure of all transformed cells tested. Dextran sulfate and heparin each can increase the DNA exposure of several different cancers. Colcemid prevents the increase of exposure of CHO by DBcAMP but it must be administered before or simultaneously with the latter compound. Measurements on mouse biopsies reveal large differences in exposure in different normal tissues. Thus, the exposure from adult liver cells was greater than that of adult brain, but both fetal liver and fetal brain had significantly greater exposure than their adult counterparts. Exposure in normal human

  1. Laparoscopic reversal of Hartmann's procedure.

    PubMed

    Fiscon, Valentino; Portale, Giuseppe; Mazzeo, Antonio; Migliorini, Giovanni; Frigo, Flavio

    2014-12-01

    Reestablishing continuity after a Hartmann's procedure is considered a major surgical procedure with high morbidity/mortality. The aim of this study was to assess the short-/long-term outcome of laparoscopic restoration of bowel continuity after HP. A prospectively collected database of colorectal laparoscopic procedures (>800) performed between June 2005 and June 2013 was used to identify 20 consecutive patients who had undergone laparoscopic reversal of Hartmann's procedure (LHR). Median age was 65.4. Ten patients (50 %) had undergone surgery for perforated diverticulitis, 3 (15 %) for cancer, and 7 (35 %) for other reasons (volvulus, posttraumatic perforation, and sigmoid perforation from foreign body). Previous HP had been performed laparoscopically in only 3 patients. Median operative time was 162.5 min. All the procedures were completed laparoscopically. Intraoperative complication rate was nil. Post-operative mortality and morbidity were respectively 0 and 10 % (1 pneumonia, 1 bowel obstruction from post-anastomotic stenosis which required resection and redo of the anastomosis). Median time to first flatus was 3 days, to normal diet 5 days. Median hospital stay was 9 days without readmissions. We followed up the patients for a median of 44 months: when asked, all 20 (100 %) said they would undergo the operation (LHR) again; 3 (15 %) had been re-operated of laparoscopic mesh repair for incisional hernia. When performed by experienced surgeons, LHR is a feasible, safe, reproducible operation, which allows early return of bowel function, early discharge and fast return to work for the patient. It has a low morbidity rate.

  2. Inhaled magnesium fluoride reverse bronchospasma.

    PubMed

    Gandia, Fedoua; Rouatbi, Sonia; Latiri, Imed; Guénard, Hervé; Tabka, Zouhair

    2010-01-01

    Asthma is a global health problem. Asthma attacks are becoming more severe and more resistant to usual treatment by beta(2) agonists nebulisation. The search for a new product that could reduce the morbidity of asthmatic disease seems necessary. The objective of this study was to compare the effectiveness of inhaled magnesium fluoride (MgF(2)) with that of magnesium sulphate (MgSO(4)) 15% alone and sodium fluoride (NaF) 0.5 M alone in rats pre-contracted by methacholine (MeCh). Fifty six adult male Wistar rats of medium weight 259 +/- 15 g were divided randomly into five groups. They inhaled respectively: MeCh, MgF(2) + NaCl 0.9%, MgF(2) + acetic acid, MgSO(4) 15% single and NaF (0.5 M) single. Airway resistances were measured after each dose of MeCh by pneumomultitest equipment. Results indicated that (1) MgF(2) + NaCl 0.9%, MgF(2) + acetic acid and MgSO(4) reversed significantly the methacholine-induced bronchial constriction in rats and had a bronchodilating effect at the moment of its administration (2) MgF(2) + acetic acid led to a greater decrease (P<0.05) of bronchial resistances when compared to that obtained from MgF(2) + NaCl 0.9%, NaF exclusively and MgSO(4) alone (3) inhaled NaF alone led to a significant bronchorelaxing effect (P<0.05) that starts at the sixth dose of MeCh (17 mg/L). As a matter of fact, MgF(2) dissolved in acetic acid and delivered in aerosol form reduces significantly bronchial spasm. In conclusion, MgF(2) can be used as a bronchodilator for diseases with bronchospasma such as asthma and chronic obstructive pulmonary disease (COPD).

  3. Exposure to metals.

    PubMed

    Hu, H

    2000-12-01

    Metals, particularly heavy metals such as lead, cadmium, and arsenic, constitute significant potential threats to human health in both occupational and environmental settings. Lead exposure is of particular concern because of ongoing exposure to thousands of workers in the US and recent research indicating that asymptomatic lead exposure can result in chronic toxicity manifestations, such as hypertension, kidney impairment, and cognitive disturbances. Mercury is neurotoxic, even at the relatively low levels of exposure seen in dentists' offices. Arsenic is clearly carcinogenic, and cadmium is now being recognized as a contributor to osteoporosis. This article reviews these and other issues of concern in the practice of primary care.

  4. Exposure assessment of trichloroethylene.

    PubMed

    Wu, C; Schaum, J

    2000-05-01

    This article reviews exposure information available for trichloroethylene (TCE) and assesses the magnitude of human exposure. The primary sources releasing TCE into the environment are metal cleaning and degreasing operations. Releases occur into all media but mostly into the air due to its volatility. It is also moderately soluble in water and can leach from soils into groundwater. TCE has commonly been found in ambient air, surface water, and groundwaters. The 1998 air levels in microg/m(3) across 115 monitors can be summarized as follows: range = 0.01-3.9, mean = 0.88. A California survey of large water utilities in 1984 found a median concentration of 3.0 microg/L. General population exposure to TCE occurs primarily by inhalation and water ingestion. Typical average daily intakes have been estimated as 11-33 microg/day for inhalation and 2-20 microg/day for ingestion. A small portion of the population is expected to have elevated exposures as a result of one or more of these pathways: inhalation exposures to workers involved in degreasing operations, ingestion and inhalation exposures occurring in homes with private wells located near disposal/contamination sites, and inhalation exposures to consumers using TCE products in areas of poor ventilation. More current and more extensive data on TCE levels in indoor air, water, and soil are needed to better characterize the distribution of background exposures in the general population and elevated exposures in special subpopulations.

  5. Exposure assessment of trichloroethylene.

    PubMed Central

    Wu, C; Schaum, J

    2000-01-01

    This article reviews exposure information available for trichloroethylene (TCE) and assesses the magnitude of human exposure. The primary sources releasing TCE into the environment are metal cleaning and degreasing operations. Releases occur into all media but mostly into the air due to its volatility. It is also moderately soluble in water and can leach from soils into groundwater. TCE has commonly been found in ambient air, surface water, and groundwaters. The 1998 air levels in microg/m(3) across 115 monitors can be summarized as follows: range = 0.01-3.9, mean = 0.88. A California survey of large water utilities in 1984 found a median concentration of 3.0 microg/L. General population exposure to TCE occurs primarily by inhalation and water ingestion. Typical average daily intakes have been estimated as 11-33 microg/day for inhalation and 2-20 microg/day for ingestion. A small portion of the population is expected to have elevated exposures as a result of one or more of these pathways: inhalation exposures to workers involved in degreasing operations, ingestion and inhalation exposures occurring in homes with private wells located near disposal/contamination sites, and inhalation exposures to consumers using TCE products in areas of poor ventilation. More current and more extensive data on TCE levels in indoor air, water, and soil are needed to better characterize the distribution of background exposures in the general population and elevated exposures in special subpopulations. Images Figure 1 PMID:10807565

  6. Age at exposure versus years of exposure.

    PubMed

    Seidman, H

    1985-05-01

    The pattern of incidence rates according to age for many forms of cancer has been found to be in reasonable accord with the equation or some modification of it: It = btk, where It is the incidence rate at age t, and b and k are constants. An alternative equation postulates that the risk of cancer is determined not by the age of a person but by the length of time exposed to a carcinogenic agent: It = b(t-w)k, where t-w represents the "effective exposure" between first exposure and clinical evidence of cancer. Mesothelioma rates in asbestos insulation workers were strongly related to time from onset of exposure regardless of age at first exposure. However, the same pattern was not evident for lung cancer mortality in the same workers compared with blue collar worker controls from the American Cancer Society Cancer Prevention Study I. Lung cancer mortality by attained rates and by duration of smoking were shown for current smokers of cigarettes only for the Cancer Society study, classified by age at which they started smoking. Lung cancer results were also given for men who never smoked regularly.

  7. Chemical reactions in reverse micelle systems

    DOEpatents

    Matson, Dean W.; Fulton, John L.; Smith, Richard D.; Consani, Keith A.

    1993-08-24

    This invention is directed to conducting chemical reactions in reverse micelle or microemulsion systems comprising a substantially discontinuous phase including a polar fluid, typically an aqueous fluid, and a microemulsion promoter, typically a surfactant, for facilitating the formation of reverse micelles in the system. The system further includes a substantially continuous phase including a non-polar or low-polarity fluid material which is a gas under standard temperature and pressure and has a critical density, and which is generally a water-insoluble fluid in a near critical or supercritical state. Thus, the microemulsion system is maintained at a pressure and temperature such that the density of the non-polar or low-polarity fluid exceeds the critical density thereof. The method of carrying out chemical reactions generally comprises forming a first reverse micelle system including an aqueous fluid including reverse micelles in a water-insoluble fluid in the supercritical state. Then, a first reactant is introduced into the first reverse micelle system, and a chemical reaction is carried out with the first reactant to form a reaction product. In general, the first reactant can be incorporated into, and the product formed in, the reverse micelles. A second reactant can also be incorporated in the first reverse micelle system which is capable of reacting with the first reactant to form a product.

  8. Why Contextual Preference Reversals Maximize Expected Value

    PubMed Central

    2016-01-01

    Contextual preference reversals occur when a preference for one option over another is reversed by the addition of further options. It has been argued that the occurrence of preference reversals in human behavior shows that people violate the axioms of rational choice and that people are not, therefore, expected value maximizers. In contrast, we demonstrate that if a person is only able to make noisy calculations of expected value and noisy observations of the ordinal relations among option features, then the expected value maximizing choice is influenced by the addition of new options and does give rise to apparent preference reversals. We explore the implications of expected value maximizing choice, conditioned on noisy observations, for a range of contextual preference reversal types—including attraction, compromise, similarity, and phantom effects. These preference reversal types have played a key role in the development of models of human choice. We conclude that experiments demonstrating contextual preference reversals are not evidence for irrationality. They are, however, a consequence of expected value maximization given noisy observations. PMID:27337391

  9. Why contextual preference reversals maximize expected value.

    PubMed

    Howes, Andrew; Warren, Paul A; Farmer, George; El-Deredy, Wael; Lewis, Richard L

    2016-07-01

    Contextual preference reversals occur when a preference for one option over another is reversed by the addition of further options. It has been argued that the occurrence of preference reversals in human behavior shows that people violate the axioms of rational choice and that people are not, therefore, expected value maximizers. In contrast, we demonstrate that if a person is only able to make noisy calculations of expected value and noisy observations of the ordinal relations among option features, then the expected value maximizing choice is influenced by the addition of new options and does give rise to apparent preference reversals. We explore the implications of expected value maximizing choice, conditioned on noisy observations, for a range of contextual preference reversal types-including attraction, compromise, similarity, and phantom effects. These preference reversal types have played a key role in the development of models of human choice. We conclude that experiments demonstrating contextual preference reversals are not evidence for irrationality. They are, however, a consequence of expected value maximization given noisy observations. (PsycINFO Database Record

  10. Novel Designs of Quantum Reversible Counters

    NASA Astrophysics Data System (ADS)

    Qi, Xuemei; Zhu, Haihong; Chen, Fulong; Zhu, Junru; Zhang, Ziyang

    2016-08-01

    Reversible logic, as an interesting and important issue, has been widely used in designing combinational and sequential circuits for low-power and high-speed computation. Though a significant number of works have been done on reversible combinational logic, the realization of reversible sequential circuit is still at premature stage. Reversible counter is not only an important part of the sequential circuit but also an essential part of the quantum circuit system. In this paper, we designed two kinds of novel reversible counters. In order to construct counter, the innovative reversible T Flip-flop Gate (TFG), T Flip-flop block (T_FF) and JK flip-flop block (JK_FF) are proposed. Based on the above blocks and some existing reversible gates, the 4-bit binary-coded decimal (BCD) counter and controlled Up/Down synchronous counter are designed. With the help of Verilog hardware description language (Verilog HDL), these counters above have been modeled and confirmed. According to the simulation results, our circuits' logic structures are validated. Compared to the existing ones in terms of quantum cost (QC), delay (DL) and garbage outputs (GBO), it can be concluded that our designs perform better than the others. There is no doubt that they can be used as a kind of important storage components to be applied in future low-power computing systems.

  11. Why contextual preference reversals maximize expected value.

    PubMed

    Howes, Andrew; Warren, Paul A; Farmer, George; El-Deredy, Wael; Lewis, Richard L

    2016-07-01

    Contextual preference reversals occur when a preference for one option over another is reversed by the addition of further options. It has been argued that the occurrence of preference reversals in human behavior shows that people violate the axioms of rational choice and that people are not, therefore, expected value maximizers. In contrast, we demonstrate that if a person is only able to make noisy calculations of expected value and noisy observations of the ordinal relations among option features, then the expected value maximizing choice is influenced by the addition of new options and does give rise to apparent preference reversals. We explore the implications of expected value maximizing choice, conditioned on noisy observations, for a range of contextual preference reversal types-including attraction, compromise, similarity, and phantom effects. These preference reversal types have played a key role in the development of models of human choice. We conclude that experiments demonstrating contextual preference reversals are not evidence for irrationality. They are, however, a consequence of expected value maximization given noisy observations. (PsycINFO Database Record PMID:27337391

  12. Vasectomy: clinical aspects and reversibility.

    PubMed

    Muangman, V

    1979-12-01

    studies involved 185 men who had a vasectomy performed at Ramathibodi Hospital. The postvasectomized man usually feels scrotal ache or discomfort for a few days. The testicular size will not change. Approximately 50% of vasectomized men showed sperm antibodies in their serum after 6 months to 1 year, which gradually diminished at 1 1/2-2 years. The studies did not reveal any significant changes in psychosexual behavior. With the standard method of vasovasostomy the rate of pregnancy of 30% is acceptable by many. Microsurgery is introduced into this field as there is a high rate of pregnancy requirement after vasectomy reversal.

  13. Reversibility and efficiency in coding protein information.

    PubMed

    Tamir, Boaz; Priel, Avner

    2010-12-21

    Why the genetic code has a fixed length? Protein information is transferred by coding each amino acid using codons whose length equals 3 for all amino acids. Hence the most probable and the least probable amino acid get a codeword with an equal length. Moreover, the distributions of amino acids found in nature are not uniform and therefore the efficiency of such codes is sub-optimal. The origins of these apparently non-efficient codes are yet unclear. In this paper we propose an a priori argument for the energy efficiency of such codes resulting from their reversibility, in contrast to their time inefficiency. Such codes are reversible in the sense that a primitive processor, reading three letters in each step, can always reverse its operation, undoing its process. We examine the codes for the distributions of amino acids that exist in nature and show that they could not be both time efficient and reversible. We investigate a family of Zipf-type distributions and present their efficient (non-fixed length) prefix code, their graphs, and the condition for their reversibility. We prove that for a large family of such distributions, if the code is time efficient, it could not be reversible. In other words, if pre-biotic processes demand reversibility, the protein code could not be time efficient. The benefits of reversibility are clear: reversible processes are adiabatic, namely, they dissipate a very small amount of energy. Such processes must be done slowly enough; therefore time efficiency is non-important. It is reasonable to assume that early biochemical complexes were more prone towards energy efficiency, where forward and backward processes were almost symmetrical. PMID:20868696

  14. EXPOSURES TO ENVIRONMENTAL AGENTS

    EPA Science Inventory

    The planned interagency National Children's Study (NCS) will be studying a number of exposure issues in the context of health and well-being of infants and young children from pre-conception to age 21. Some of the important environmental exposure questions for NCS, include: how c...

  15. Avian inhalation exposure chamber

    DOEpatents

    Briant, James K.; Driver, Crystal J.

    1992-01-01

    An exposure system for delivering gaseous material ranging in particle size from 0.4 micrometers to 20.0 micrometers uniformly to the heads of experimental animals, primarily birds. The system includes a vertical outer cylinder and a central chimney with animal holding bottles connected to exposure ports on the vertical outer cylinder.

  16. Avian inhalation exposure chamber

    DOEpatents

    Briant, J.K.; Driver, C.J.

    1992-05-05

    An exposure system is designed for delivering gaseous material ranging in particle size from 0.4 micrometers to 20.0 micrometers uniformly to the heads of experimental animals, primarily birds. The system includes a vertical outer cylinder and a central chimney with animal holding bottles connected to exposure ports on the vertical outer cylinder. 2 figs.

  17. Environmental Exposures and Development

    PubMed Central

    Mattison, Donald R.

    2010-01-01

    Structured Abstract Purpose of Review Summarize recent studies exploring the relationship between paternal and maternal environmental exposures to chemicals before, at the time of and after conception to adverse developmental outcomes including; preterm birth, death, structural and functional abnormalities and growth restriction. Recent Findings Recent studies have demonstrated that human pregnancy and development is vulnerable to environmental exposures of the father and mother to chemical, biological and physical agents. Exposures associated with adverse developmental outcomes include; air and water pollution, chemicals in foods, occupational exposures, agricultural chemicals, metals, persistent and volatile organics. Developmental endpoints which are linked with these exposures include; growth restriction, functional abnormalities, structural abnormalities, preterm delivery and death. Despite this general understanding we still have incomplete knowledge concerning most exposures and the biological interactions responsible for impaired development and preterm delivery. Summary While single genes and individual chemical exposures are responsible for some instances of adverse pregnancy outcome or developmental disease, gene-environment interactions are responsible for the majority. These gene-environment interactions may occur in the father, mother, placenta or fetus suggesting that critical attention be given to maternal and paternal exposures and gene expression as they relate to the mode of action of the putative developmental toxicant both prior to and during pregnancy. PMID:20216314

  18. A Revealing Exposure.

    ERIC Educational Resources Information Center

    Evans, Kenneth H.

    1992-01-01

    Describes an activity in which students examine hypothetical exposure to toxins by being showered by different colored pieces of confetti over several visits to exposure sites. Students record quantities of confetti that stick to packing tape. Colors correspond to different toxins posing different health problems. Students process their findings…

  19. IMMUNOASSAY HUMAN EXPOSURE STUDIES

    EPA Science Inventory

    The Human Exposure Research Branch has developed several enzyme-linked immunosorbent assay (ELISA) methods to support human exposure assessment studies. Immunoassays to detect low levels (<10 ng/mL) of chlorpyrifos in food, track-in dirt and house dust have been applied to sam...

  20. An insightful approach for understanding solvatochromic reversal

    NASA Astrophysics Data System (ADS)

    Manzoni, Vinicius; Coutinho, Kaline; Canuto, Sylvio

    2016-07-01

    Several studies have shown that organic dyes may show solvatochromic reversal with respect to the solvent polarity. This controversial non-monotonic behavior is still not well understood. This has been analyzed here using the merocyanine of Brooker as the working example. Associating a continuous variable to model the solvent polarity a solvatochromic reversal is obtained with a single solute without aggregation. This reversal is in excellent agreement with the experimental results and is shown to be the outcome of a competition between structural change and intramolecular charge transfer.

  1. Time reversibility in the quantum frame

    SciTech Connect

    Masot-Conde, Fátima

    2014-12-04

    Classic Mechanics and Electromagnetism, conventionally taken as time-reversible, share the same concept of motion (either of mass or charge) as the basis of the time reversibility in their own fields. This paper focuses on the relationship between mobile geometry and motion reversibility. The goal is to extrapolate the conclusions to the quantum frame, where matter and radiation behave just as elementary mobiles. The possibility that the asymmetry of Time (Time’s arrow) is an effect of a fundamental quantum asymmetry of elementary particles, turns out to be a consequence of the discussion.

  2. Reverse logistics in the Brazilian construction industry.

    PubMed

    Nunes, K R A; Mahler, C F; Valle, R A

    2009-09-01

    In Brazil most Construction and Demolition Waste (C&D waste) is not recycled. This situation is expected to change significantly, since new federal regulations oblige municipalities to create and implement sustainable C&D waste management plans which assign an important role to recycling activities. The recycling organizational network and its flows and components are fundamental to C&D waste recycling feasibility. Organizational networks, flows and components involve reverse logistics. The aim of this work is to introduce the concepts of reverse logistics and reverse distribution channel networks and to study the Brazilian C&D waste case. PMID:19481331

  3. Methane Screening in JET Reverse Field Experiments

    SciTech Connect

    J.D. Strachan; B. Alper; G. Corrigan; S.K. Erents; C. Giroud; A. Korotkov; H. Leggate; G.F. Mathews; R.A. Pitts; M. Stamp; J. Spence

    2004-05-17

    JET plasmas with reverse magnetic field feature a different SOL flow than those with normal field. The observed carbon fueling efficiency from injecting methane gas was similar in reverse and normal field. EDGE2D modeling used an externally applied force to create the SOL flows, without specifying the origin of the force. The resulting flow agreed reasonably with the experimental values between the separatrix and 4 cm mid-plane depth in the SOL. The effect of the flow on the calculated carbon screening was 5 to 15% higher carbon fueling efficiency for the low flow velocity with reverse field.

  4. Cheaper Adjoints by Reversing Address Computations

    DOE PAGESBeta

    Hascoët, L.; Utke, J.; Naumann, U.

    2008-01-01

    The reverse mode of automatic differentiation is widely used in science and engineering. A severe bottleneck for the performance of the reverse mode, however, is the necessity to recover certain intermediate values of the program in reverse order. Among these values are computed addresses, which traditionally are recovered through forward recomputation and storage in memory. We propose an alternative approach for recovery that uses inverse computation based on dependency information. Address storage constitutes a significant portion of the overall storage requirements. An example illustrates substantial gains that the proposed approach yields, and we show use cases in practical applications.

  5. Extending the boundaries of reverse engineering

    NASA Astrophysics Data System (ADS)

    Lawrie, Chris

    2002-04-01

    In today's market place the potential of Reverse Engineering as a time compression tool is commonly lost under its traditional definition. The term Reverse Engineering was coined way back at the advent of CMM machines and 3D CAD systems to describe the process of fitting surfaces to captured point data. Since these early beginnings, downstream hardware scanning and digitising systems have evolved in parallel with an upstream demand, greatly increasing the potential of a point cloud data set within engineering design and manufacturing processes. The paper will discuss the issues surrounding Reverse Engineering at the turn of the millennium.

  6. [Ozone exposure and asthma].

    PubMed

    Kleis, S; Louis, R; Bartsch, P

    2003-03-01

    Ozone is a pollutant the production of which depends on weather conditions and car engine combustion. Numerous epidemiological studies have indicated that high ozone levels correlated with morbidity in asthma. Experimental studies have shown that exposure of healthy subjects and asthmatics to ozone levels comparable to those measured in ambient air during hot summer days can generate respiratory symptoms, neutrophilic airways inflammation and lung function impairment. Lung function changes following ozone exposure are more pronounced in asthmatics and are dependent on the duration and intensity of exposure, a previous exposure and the nutritional status of the subjects. The airway epithelial cell layer is likely to play a pivotal role in initiating the inflammatory process following ozone exposure. Control of ambient air ozone levels must be a target for public health authorities.

  7. Rational strategy for shaped nanomaterial synthesis in reverse micelle reactors

    NASA Astrophysics Data System (ADS)

    Wei, Zengyan; Matsui, Hiroshi

    2014-05-01

    The shape-controlled synthesis of nanoparticles was established in single-phase solutions by controlling growth directions of crystalline facets on seed nanocrystals kinetically; however, it was difficult to rationally predict and design nanoparticle shapes. Here we introduce a methodology to fabricate nanoparticles in smaller sizes by evolving shapes thermodynamically. This strategy enables a more rational approach to fabricate shaped nanoparticles by etching specific positions of atoms on facets of seed nanocrystals in reverse micelle reactors where the surface energy gradient induces desorption of atoms on specific locations on the seed surfaces. From seeds of 12-nm palladium nanocubes, the shape is evolved to concave nanocubes and finally hollow nanocages in the size ~10 nm by etching the centre of {200} facets. The high surface area-to-volume ratio and the exposure of a large number of palladium atoms on ledge and kink sites of hollow nanocages are advantageous to enhance catalytic activity and recyclability.

  8. Rational strategy for shaped nanomaterial synthesis in reverse micelle reactors

    PubMed Central

    Wei, Zengyan; Matsui, Hiroshi

    2014-01-01

    The shape-controlled synthesis of nanoparticles was established in single-phase solutions by controlling growth directions of crystalline facets on seed nanocrystals kinetically; however, it was difficult to rationally predict and design nanoparticle shapes. Here we introduce a methodology to fabricate nanoparticles in smaller sizes by evolving shapes thermodynamically. This strategy enables a more rational approach to fabricate shaped nanoparticles by etching specific positions of atoms on facets of seed nanocrystals in reverse micelle reactors where the surface energy gradient induces desorption of atoms on specific locations on the seed surfaces. From seeds of 12 nm palladium nanocubes, the shape is evolved to concave nanocubes and finally hollow nanocages in the size ~10 nm by etching the center of {200} facets. The high surface area-to-volume ratio and the exposure of a large number of palladium atoms on ledge and kink sites of hollow nanocages are advantageous to enhance catalytic activity and recyclability. PMID:24828960

  9. Quaternary naltrexone reverses radiogenic and morphine-induced locomotor hyperactivity

    SciTech Connect

    Mickley, G.A.; Stevens, K.E.; Galbraith, J.A.; White, G.A.; Gibbs, G.L.

    1984-04-01

    The present study attempted to determine the relative role of the peripheral and central nervous system in the production of morphine-induced or radiation-induced locomotor hyperactivity of the mouse. Toward this end, we used a quaternary derivative of an opiate antagonist (naltrexone methobromide), which presumably does not cross the blood-brain barrier. Quaternary naltrexone was used to challenge the stereotypic locomotor response observed in these mice after either an i.p. injection of morphine or exposure to 1500 rads /sup 60/Co. The quaternary derivative of naltrexone reversed the locomotor hyperactivity normally observed in the C57BL/6J mouse after an injection of morphine. It also significantly attenuated radiation-induced locomotion. The data reported here support the hypothesis of endorphin involvement in radiation-induced and radiogenic behaviors. However, these conclusions are contingent upon further research which more fully evaluates naltrexone methobromide's capacity to cross the blood-brain barrier.

  10. Modulation of Cu(2-x)S Nanocrystal Plasmon Resonance through Reversible Photoinduced Electron Transfer.

    PubMed

    Alam, Rabeka; Labine, Molly; Karwacki, Christopher J; Kamat, Prashant V

    2016-02-23

    Copper sulfide (Cu(2-x)S) nanocrystals with nonstoichiometric composition exhibit plasmon resonance in the near-infrared region. Compositional changes and varying electron density markedly affect the position and intensity of the plasmon resonance. We report a photochemically induced phenomenon of modulating the plasmon resonance in a controlled fashion. As photogenerated reduced methyl viologen radicals transfer electrons to Cu(2-x)S in inert solutions, we observe a decrease in localized surface plasmon resonance (LSPR) absorbance at 1160 nm. Upon exposure to air, the plasmon resonance band recovers as stored electrons are scavenged away by oxygen. This cycle of electron charge and discharge of Cu(2-x)S nanocrystals is reversible and can be repeated through photoirradiation in N2 saturated solution followed by exposure of the suspension to air. The spectroscopic studies that provide mechanistic insights into the reversible charging and discharging of plasmonic Cu(2-x)S are discussed.

  11. Visually induced self-motion sensation adapts rapidly to left-right reversal of vision

    NASA Technical Reports Server (NTRS)

    Oman, C. M.; Bock, O. L.

    1981-01-01

    Three experiments were conducted using 15 adult volunteers with no overt oculomotor or vestibular disorders. In all experiments, left-right vision reversal was achieved using prism goggles, which permitted a binocular field of vision subtending approximately 45 deg horizontally and 28 deg vertically. In all experiments, circularvection (CV) was tested before and immediately after a period of exposure to reversed vision. After one to three hours of active movement while wearing vision-reversing goggles, 10 of 15 (stationary) human subjects viewing a moving stripe display experienced a self-rotation illusion in the same direction as seen stripe motion, rather than in the opposite (normal) direction, demonstrating that the central neural pathways that process visual self-rotation cues can undergo rapid adaptive modification.

  12. Time-reversal acoustics and ultrasound-assisted convection-enhanced drug delivery to the brain.

    PubMed

    Olbricht, William; Sistla, Manjari; Ghandi, Gaurav; Lewis, George; Sarvazyan, Armen

    2013-08-01

    Time-reversal acoustics is an effective way of focusing ultrasound deep inside heterogeneous media such as biological tissues. Convection-enhanced delivery is a method of delivering drugs into the brain by infusing them directly into the brain interstitium. These two technologies are combined in a focusing system that uses a "smart needle" to simultaneously infuse fluid into the brain and provide the necessary feedback for focusing ultrasound using time-reversal acoustics. The effects of time-reversal acoustics-focused ultrasound on the spatial distribution of infused low- and high-molecular weight tracer molecules are examined in live, anesthetized rats. Results show that exposing the rat brain to focused ultrasound significantly increases the penetration of infused compounds into the brain. The addition of stabilized microbubbles enhances the effect of ultrasound exposure.

  13. Time-reversal acoustics and ultrasound-assisted convection-enhanced drug delivery to the brain.

    PubMed

    Olbricht, William; Sistla, Manjari; Ghandi, Gaurav; Lewis, George; Sarvazyan, Armen

    2013-08-01

    Time-reversal acoustics is an effective way of focusing ultrasound deep inside heterogeneous media such as biological tissues. Convection-enhanced delivery is a method of delivering drugs into the brain by infusing them directly into the brain interstitium. These two technologies are combined in a focusing system that uses a "smart needle" to simultaneously infuse fluid into the brain and provide the necessary feedback for focusing ultrasound using time-reversal acoustics. The effects of time-reversal acoustics-focused ultrasound on the spatial distribution of infused low- and high-molecular weight tracer molecules are examined in live, anesthetized rats. Results show that exposing the rat brain to focused ultrasound significantly increases the penetration of infused compounds into the brain. The addition of stabilized microbubbles enhances the effect of ultrasound exposure. PMID:23927197

  14. Agonistic induction of PPARγ reverses cigarette smoke–induced emphysema

    PubMed Central

    Shan, Ming; You, Ran; Yuan, Xiaoyi; Frazier, Michael V.; Porter, Paul; Seryshev, Alexander; Hong, Jeong-Soo; Song, Li-zhen; Zhang, Yiqun; Hilsenbeck, Susan; Whitehead, Lawrence; Zarinkamar, Nazanin; Perusich, Sarah; Corry, David B.; Kheradmand, Farrah

    2014-01-01

    The development of emphysema in humans and mice exposed to cigarette smoke is promoted by activation of an adaptive immune response. Lung myeloid dendritic cells (mDCs) derived from cigarette smokers activate autoreactive Th1 and Th17 cells. mDC-dependent activation of T cell subsets requires expression of the SPP1 gene, which encodes osteopontin (OPN), a pleiotropic cytokine implicated in autoimmune responses. The upstream molecular events that promote SPP1 expression and activate mDCs in response to smoke remain unknown. Here, we show that peroxisome proliferator–activated receptor γ (PPARG/Pparg) expression was downregulated in mDCs of smokers with emphysema and mice exposed to chronic smoke. Conditional knockout of PPARγ in APCs using Cd11c-Cre Ppargflox/flox mice led to spontaneous lung inflammation and emphysema that resembled the phenotype of smoke-exposed mice. The inflammatory phenotype of Cd11c-Cre Ppargflox/flox mice required OPN, suggesting an antiinflammatory mechanism in which PPARγ negatively regulates Spp1 expression in the lung. A 2-month treatment with a PPARγ agonist reversed emphysema in WT mice despite continual smoke exposure. Furthermore, endogenous PPARγ agonists were reduced in the plasma of smokers with emphysema. These findings reveal a proinflammatory pathway, in which reduced PPARγ activity promotes emphysema, and suggest that targeting this pathway in smokers could prevent and reverse emphysema. PMID:24569375

  15. Epigenetic reversion of breast carcinoma phenotype is accompaniedby DNA sequestration

    SciTech Connect

    Sandal, Tone; Valyi-Nagy, Klara; Spencer, Virginia A.; Folberg,Robert; Bissell, Mina J.; Maniotis, Andrew J.

    2006-07-19

    The importance of microenvironment and context in regulation of tissue-specific genes is finally well established. DNA exposure to, or sequestration from, nucleases can be used to detect differences in higher order chromatin structure in intact cells without disturbing cellular or tissue architecture. To investigate the relationship between chromatin organization and tumor phenotype, we utilized an established 3-D assay where normal and malignant human breast cells can be easily distinguished by the morphology of the structures they make (acinus-like vs tumor-like, respectively). We show that these phenotypes can be distinguished also by sensitivity to AluI digestion where the malignant cells are resistant to digestion relative to non-malignant cells. Reversion of the T4-2 breast cancer cells by either cAMP analogs, or a phospatidylinositol 3-kinase (P13K) inhibitor not only reverted the phenotype, but also the chromatin sensitivity to AluI. By using different cAMP-analogs, we show that the cAMP-induced phenotypic reversion, polarization, and shift in DNA organization act through a cAMP-dependent-protein-kinase A-coupled signaling pathway. Importantly, inhibitory antibody to fibronectin also reverted the malignant phenotype, polarized the acini, and changed chromatin sequestration. These experiments show not only that modifying the tumor microenvironment can alter the organization of tumor cells but also that architecture of the tissues and the global chromatin organization are coupled and yet highly plastic.

  16. Reverse Transcription by Escherichia coli DNA Polymerase I

    PubMed Central

    Karkas, John D.

    1973-01-01

    E. coli DNA polymerase I (EC 2.7.7.7) can engage in either DNA- or RNA-directed DNA synthesis with hybrid templates. The choice of the strand to be transcribed depends primarily on the relative lengths of the two strands of the hybrid, the longer strand serving as the template and the shorter as the primer. If a polynucleotide is reduced in size by exposure to an endonuclease before being hybridized to the complementary strand, the template efficiency of the latter increases several-fold. Under properly selected conditions, highly efficient reverse transcription of the all-ribonucleotide template-primers poly(A)·oligo(U), poly(C)·oligo(I), and poly(I)·oligo(C) can be achieved. “f1 RNA,” the RNA strand of an f1 DNA·RNA hybrid, can also serve as template for reverse transcription either after “nicking” of the hybrid with DNase, or after separation from the DNA strand and priming by DNase-treated f1 DNA. PMID:4129927

  17. Tick-borne pathogen - reversed and conventional discovery of disease.

    PubMed

    Tijsse-Klasen, Ellen; Koopmans, Marion P G; Sprong, Hein

    2014-01-01

    Molecular methods have increased the number of known microorganisms associated with ticks significantly. Some of these newly identified microorganisms are readily linked to human disease while others are yet unknown to cause human disease. The face of tick-borne disease discovery has changed with more diseases now being discovered in a "reversed way," detecting disease cases only years after the tick-borne microorganism was first discovered. Compared to the conventional discovery of infectious diseases, reverse order discovery presents researchers with new challenges. Estimating public health risks of such agents is especially challenging, as case definitions and diagnostic procedures may initially be missing. We discuss the advantages and shortcomings of molecular methods, serology, and epidemiological studies that might be used to study some fundamental questions regarding newly identified tick-borne diseases. With increased tick-exposure and improved detection methods, more tick-borne microorganisms will be added to the list of pathogens causing disease in humans in the future. PMID:25072045

  18. Constraining the reversing and non-reversing modes of the geodynamo. New insights from magnetostratigraphy.

    NASA Astrophysics Data System (ADS)

    Gallet, Y.; Pavlov, V.; Shatsillo, A.; Hulot, G.

    2015-12-01

    Constraining the evolution in the geomagnetic reversal frequency over hundreds of million years is not a trivial matter. Beyond the fact that there are long periods without reversals, known as superchrons, and periods with many reversals, the way the reversal frequency changes through time during reversing periods is still debated. A smooth evolution or a succession of stationary segments have both been suggested to account for the geomagnetic polarity time scale since the Middle-Late Jurassic. Sudden changes from a reversing mode to a non-reversing mode of the geodynamo may also well have happened, the switch between the two modes having then possibly been controlled by the thermal conditions at the core-mantle boundary. There is, nevertheless, a growing set of magnetostratigraphic data, which could help decipher a proper interpretation of the reversal history, in particular in the early Paleozoic and even during the Precambrian. Although yielding a fragmentary record, these data reveal the occurrence of both additional superchrons and periods characterized by extremely high, not to say extraordinary, magnetic reversal frequencies. In this talk, we will present a synthesis of these data, mainly obtained from Siberia, and discuss their implication for the magnetic reversal behavior over the past billion years.

  19. Reverse Engineering Adverse Outcome Pathways in Ecotoxicology

    EPA Science Inventory

    The toxicological effects of many stressors are mediated through unknown, or incompletely characterized, mechanisms of action. We describe the application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, meabolic, signaling) t...

  20. The reverse laser drilling of transparent materials

    NASA Technical Reports Server (NTRS)

    Anthony, T. R.; Lindner, P. A.

    1980-01-01

    Within a limited range of incident laser-beam intensities, laser drilling of a sapphire wafer initiates on the surface of the wafer where the laser beam exits and proceeds upstream in the laser beam to the surface where the laser beam enters the wafer. This reverse laser drilling is the result of the constructive interference between the laser beam and its reflected component on the exit face of the wafer. Constructive interference occurs only at the exit face of the sapphire wafer because the internally reflected laser beam suffers no phase change there. A model describing reverse laser drilling predicts the ranges of incident laser-beam intensity where no drilling, reverse laser drilling, and forward laser drilling can be expected in various materials. The application of reverse laser drilling in fabricating feed-through conductors in silicon-on-sapphire wafers for a massively parallel processer is described.

  1. Reverse-osmosis membranes by plasma polymerization

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.

  2. Reversibility of hyperhidrosis post axillary depilatory laser.

    PubMed

    Helou, Josiane; Habre, Maya; Soutou, Boutros; Maatouk, Ismael; Ibrahim, Tony; Tomb, Roland

    2014-03-01

    Hyperhidrosis and bromhidrosis were lately reported as novel side effects of laser-assisted removal of axillary hair. The goal of our study was to evaluate the reversibility of these two side effects. An observational, single-center cohort study included over a 30-month screening period 30 patients with newly reported hyperhidrosis and/or bromhidrosis related to axillary depilatory laser. After 26 weeks of follow-up, each patient was assessed for spontaneous reversibility. A 12-week duration treatment with topical aluminum chloride was evaluated in patients with persisting hyperhidrosis. Hyperhidrosis was assessed using the Hyperhidrosis Disease Severity Scale (HDSS). Spontaneous reversibility was observed in 20% of patients. In total, 23 out of 30 patients recovered normal axillary transpiration either spontaneously or after treatment. Mean HDSS score was significantly lower in the treated group. It appears that axillary hyperhidrosis and bromhidrosis, secondary to laser depilation, reverse either spontaneously or after using topical antiperspirant. PMID:23887660

  3. Galen: developer of the reversal design?

    PubMed

    Brown, Robert T

    2007-01-01

    Galen, known to psychologists largely for his personality theory of the four temperaments, diagnosed the cause of a patient's symptoms with a form of reversal design long before its formal description (e.g., Sidman, 1960).

  4. Flow reversal power limit for the HFBR

    SciTech Connect

    Cheng, Lap Y.; Tichler, P.R.

    1995-10-01

    The High Flux Beam Reactor (HFBR) undergoes a buoyancy-driven reversal of flow in the reactor core following certain postulated accidents. Uncertainties about the afterheat removal capability during the flow reversal has limited the reactor operating power to 30 MW. An experimental and analytical program to address these uncertainties is described in this report. The experiments were single channel flow reversal tests under a range of conditions. The analytical phase involved simulations of the tests to benchmark the physical models and development of a criterion for dryout. The criterion is then used in simulations of reactor accidents to determine a safe operating power level. It is concluded that the limit on the HFBR operating power with respect to the issue of flow reversal is in excess of 60 MW.

  5. Galen: Developer of the Reversal Design?

    PubMed Central

    Brown, Robert T

    2007-01-01

    Galen, known to psychologists largely for his personality theory of the four temperaments, diagnosed the cause of a patient's symptoms with a form of reversal design long before its formal description (e.g., Sidman, 1960). PMID:22478486

  6. Reversible Oxygenation of Oxygen Transport Proteins.

    ERIC Educational Resources Information Center

    Drain, C. M.; Corden, Barry B.

    1987-01-01

    Describes a lecture demonstration which illustrates changes in the visible spectra of oxygen transport proteins upon reversible oxygen binding. Provides a comparison of the physical characteristics of oxygen storage and transport proteins. Reviews essentials for preparation of the materials. (ML)

  7. Optical reversible programmable Boolean logic unit.

    PubMed

    Chattopadhyay, Tanay

    2012-07-20

    Computing with reversibility is the only way to avoid dissipation of energy associated with bit erase. So, a reversible microprocessor is required for future computing. In this paper, a design of a simple all-optical reversible programmable processor is proposed using a polarizing beam splitter, liquid crystal-phase spatial light modulators, a half-wave plate, and plane mirrors. This circuit can perform 16 logical operations according to three programming inputs. Also, inputs can be easily recovered from the outputs. It is named the "reversible programmable Boolean logic unit (RPBLU)." The logic unit is the basic building block of many complex computational operations. Hence the design is important in sense. Two orthogonally polarized lights are defined here as two logical states, respectively.

  8. Local heating realization by reverse thermal cloak

    PubMed Central

    Hu, Run; Wei, Xuli; Hu, Jinyan; Luo, Xiaobing

    2014-01-01

    Transformation thermodynamics, as one of the important branches among the extensions of transformation optics, has attracted plentiful attentions and interests recently. The result of transformation thermodynamics, or called as “thermal cloak”, can realize isothermal region and hide objects from heat. In this paper, we presented the concept of “reverse thermal cloak” to correspond to the thermal cloak and made a simple engineering definition to identify them. By full-wave simulations, we verified that the reverse thermal cloak can concentrate heat and realize local heating. The performance of local heating depends on the anisotropic dispersion of the cloaking layer's thermal conductivity. Three-dimensional finite element simulations demonstrated that the reverse thermal cloak can be used to heat up objects. Besides pre-engineered metamaterials, such reverse thermal cloak can even be realized with homogenous materials by alternating spoke-like structure or Hashin coated-sphere structure. PMID:24398592

  9. Reversibility of hyperhidrosis post axillary depilatory laser.

    PubMed

    Helou, Josiane; Habre, Maya; Soutou, Boutros; Maatouk, Ismael; Ibrahim, Tony; Tomb, Roland

    2014-03-01

    Hyperhidrosis and bromhidrosis were lately reported as novel side effects of laser-assisted removal of axillary hair. The goal of our study was to evaluate the reversibility of these two side effects. An observational, single-center cohort study included over a 30-month screening period 30 patients with newly reported hyperhidrosis and/or bromhidrosis related to axillary depilatory laser. After 26 weeks of follow-up, each patient was assessed for spontaneous reversibility. A 12-week duration treatment with topical aluminum chloride was evaluated in patients with persisting hyperhidrosis. Hyperhidrosis was assessed using the Hyperhidrosis Disease Severity Scale (HDSS). Spontaneous reversibility was observed in 20% of patients. In total, 23 out of 30 patients recovered normal axillary transpiration either spontaneously or after treatment. Mean HDSS score was significantly lower in the treated group. It appears that axillary hyperhidrosis and bromhidrosis, secondary to laser depilation, reverse either spontaneously or after using topical antiperspirant.

  10. Reversible Michael additions: covalent inhibitors and prodrugs.

    PubMed

    Johansson, Martin H

    2012-11-01

    Covalent inhibition is an efficient molecular mechanism for inhibiting enzymes or modulating the function of proteins and is found in the action of many drugs and biologically active natural products. However, it is has been less appreciated that the formation of covalent bonds can be reversible or irreversible. This review focuses on biologically active compounds that are Michael acceptors and how the reversible nature of the Michael addition reaction influences biological activity and how this can be exploited in designing prodrugs.

  11. Predicting trend reversals using market instantaneous state

    NASA Astrophysics Data System (ADS)

    Bury, Thomas

    2014-06-01

    Collective behaviors taking place in financial markets reveal strongly correlated states especially during a crisis period. A natural hypothesis is that trend reversals are also driven by mutual influences between the different stock exchanges. Using a maximum entropy approach, we find coordinated behavior during trend reversals dominated by the pairwise component. In particular, these events are predicted with high significant accuracy by the ensemble's instantaneous state.

  12. MODIFIED BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE

    SciTech Connect

    Au, Ming

    2006-05-10

    This paper reports the results in the effort to destabilize lithium borohydride for reversible hydrogen storage. A number of metals, metal hydrides, metal chlorides and complex hydrides were selected and evaluated as the destabilization agents for reducing dehydriding temperature and generating dehydriding-rehydriding reversibility. It is found that some additives are effective. The Raman spectroscopic analysis shows the change of B-H binding nature.

  13. Miniature Reversal Electron-Attachment Detector

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara

    1994-01-01

    Miniature reversal electron-attachment detector (miniREAD) enables direct injection of air or vapor at atmospheric pressure from monitored area into mass-spectrometric instrument to detect explosives, narcotics, or other substances, vapors of which suspected of being present in low concentrations. In comparison with older reversal electron-attachment detector, miniREAD simpler in design; more rugged; and easier to build, repair, and maintain. In addition, probably more sensitive.

  14. How the geomagnetic field vector reverses polarity

    USGS Publications Warehouse

    Prevot, M.; Mankinen, E.A.; Gromme, C.S.; Coe, R.S.

    1985-01-01

    A highly detailed record of both the direction and intensity of the Earth's magnetic field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals. ?? 1985 Nature Publishing Group.

  15. Another look at children's symbol reversals.

    PubMed

    Patton, J E; Yarbrough, D B; Thursby, D

    2000-04-01

    In a previously reported longitudinal study of reversal errors for static and kinetic written symbols we found no compelling support for their academic importance in kindergarten (n = 201), Grade 1 (n = 156), or Grade 2 (n = 129); however, for Grade 3 (n = 105), kinetic reversals became a significant predictor of tested reading achievement. If reliable, this finding might have implications for the identification of children with long-term reading impairment. PMID:10833756

  16. RNA virus reverse genetics and vaccine design.

    PubMed

    Stobart, Christopher C; Moore, Martin L

    2014-06-25

    RNA viruses are capable of rapid spread and severe or potentially lethal disease in both animals and humans. The development of reverse genetics systems for manipulation and study of RNA virus genomes has provided platforms for designing and optimizing viral mutants for vaccine development. Here, we review the impact of RNA virus reverse genetics systems on past and current efforts to design effective and safe viral therapeutics and vaccines.

  17. RNA Virus Reverse Genetics and Vaccine Design

    PubMed Central

    Stobart, Christopher C.; Moore, Martin L.

    2014-01-01

    RNA viruses are capable of rapid spread and severe or potentially lethal disease in both animals and humans. The development of reverse genetics systems for manipulation and study of RNA virus genomes has provided platforms for designing and optimizing viral mutants for vaccine development. Here, we review the impact of RNA virus reverse genetics systems on past and current efforts to design effective and safe viral therapeutics and vaccines. PMID:24967693

  18. Geomagnetic reversal in brunhes normal polarity epoch.

    PubMed

    Smith, J D; Foster, J H

    1969-02-01

    The magnetic stratigraphly of seven cores of deep-sea sediment established the existence of a short interval of reversed polarity in the upper part of the Brunches epoch of normal polarity. The reversed zone in the cores correlates well with paleontological boundaries and is named the Blake event. Its boundaries are estimated to be 108,000 and 114,000 years ago +/- 10 percent. PMID:17750890

  19. Emerging Indications for Reverse Shoulder Arthroplasty.

    PubMed

    Urch, Ekaterina; Dines, Joshua S; Dines, David M

    2016-01-01

    Historically, reverse shoulder arthroplasty was reserved for older, low-demand patients in whom rotator cuff arthropathy was diagnosed. Other common indications included sequelae of previously treated proximal humerus fractures, failed anatomic total shoulder arthroplasty, tumor resection, and rheumatoid arthritis in the elderly population. Unpredictable implant durability and high complication rates have limited the use of reverse shoulder arthroplasty to a narrow group of patients. Over the past decade, however, research has led to an improved understanding of the biomechanics behind reverse shoulder prostheses, which has improved implant design and surgical techniques. Consequently, orthopaedic surgeons have slowly begun to expand the indications for reverse shoulder arthroplasty to include a wider spectrum of shoulder pathologies. Recent studies have shown promising results for patients who undergo reverse shoulder arthroplasty for the treatment of acute proximal humerus fractures, massive rotator cuff tears without arthropathy, primary osteoarthritis, and chronic anterior dislocation, as well as for younger patients who have rheumatoid arthritis. These data suggest that, with judicious patient selection, reverse shoulder arthroplasty can be an excellent treatment option for a growing patient cohort. PMID:27049188

  20. Time reversals of irreversible quantum maps

    NASA Astrophysics Data System (ADS)

    Aurell, Erik; Zakrzewski, Jakub; Życzkowski, Karol

    2015-09-01

    We propose an alternative notion of time reversal in open quantum systems as represented by linear quantum operations, and a related generalization of classical entropy production in the environment. This functional is the ratio of the probability to observe a transition between two states under the forward and the time reversed dynamics, and leads, as in the classical case, to fluctuation relations as tautological identities. As in classical dynamics in contact with a heat bath, time reversal is not unique, and we discuss several possibilities. For any bistochastic map its dual map preserves the trace and describes a legitimate dynamics reversed in time, in that case the entropy production in the environment vanishes. For a generic stochastic map we construct a simple quantum operation which can be interpreted as a time reversal. For instance, the decaying channel, which sends the excited state into the ground state with a certain probability, can be reversed into the channel transforming the ground state into the excited state with the same probability.